Manufacturing and assembly technologies - Assembly and joining processes1

Manufacturing and assembly technologies - Assembly and joining processes1 https://slideplayer.com/slide/10673763/

Sheet-Metal Forming Manufacturing and assembly technologies - Assembly and joining processes2 SHEET-METAL FORMING PROCESS https://slideplayer.com/slide/10673763/

Sheet Metal Forming Process Manufacturing and assembly technologies - Assembly and joining processes3

4 Sheet Metal Forming Process

Manufacturing and assembly technologies - Assembly and joining processes5 Characteristics of Sheet Metal Forming Process

Manufacturing and assembly technologies - Assembly and joining processes6 Sheet Metal - Characteristics and Formability

Manufacturing and assembly technologies - Assembly and joining processes7 Sheet Metal - Characteristics and Formability

Manufacturing and assembly technologies - Assembly and joining processes8 Characteristics of Sheet-Metal Forming Processes

Shearing Manufacturing and assembly technologies - Assembly and joining processes16 Figure: (a)Schematic illustration of shearing with a punch and die, indicating some of the process variables. (b)Characteristic features of a punched hole and (c)The slug. Note that the scales of the two figures are different

Shearing (Cont’d) Manufacturing and assembly technologies - Assembly and joining processes17

Manufacturing and assembly technologies - Assembly and joining processes18 Shearing operation

Manufacturing and assembly technologies - Assembly and joining processes19 Other shearing operation

Manufacturing and assembly technologies - Assembly and joining processes20

Manufacturing and assembly technologies - Assembly and joining processes21 Shearing dies

Manufacturing and assembly technologies - Assembly and joining processes22 Compound dies

Manufacturing and assembly technologies - Assembly and joining processes24 Sheet Metal Characteristic

Yield point elongation Manufacturing and assembly technologies - Assembly and joining processes25

Manufacturing and assembly technologies - Assembly and joining processes26 Anisotropy

Manufacturing and assembly technologies - Assembly and joining processes28 Cupping test

Manufacturing and assembly technologies - Assembly and joining processes29 Bending sheet and plate

Manufacturing and assembly technologies - Assembly and joining processes30 Bend allowance

Manufacturing and assembly technologies - Assembly and joining processes31 Spring Back

Manufacturing and assembly technologies - Assembly and joining processes32 Cont’d

Manufacturing and assembly technologies - Assembly and joining processes33 Bending force

Manufacturing and assembly technologies - Assembly and joining processes34 Roll bending

Manufacturing and assembly technologies - Assembly and joining processes35 Bending

Manufacturing and assembly technologies - Assembly and joining processes37 …few words about the anisotropic When the properties of a material vary with different crystallographic orientations, the material is said to be anisotropic. Alternately, when the properties of a material are the same in all directions, the material is said to be isotropic. What is anisotropy and example? anisotropy, in physics, the quality of exhibiting properties with different values when measured along axes in different directions.... A familiar example of anisotropy is double refraction or birefringence, the difference in the speed of light along different axes of crystals of the mineral calcite. What is anisotropy in sheet metal? During sheet metal forming, anisotropic properties of a material usually exhibit two different forms.... Another anisotropic property is the different thinning values when measured along the plane of the sheet instead of through the thickness direction. What is the meaning of isotropic and anisotropic? Isotropic refers to the properties of a material which is independent of the direction whereas anisotropic is direction-dependent. These two terms are used to explain the properties of the material in basic crystallography.

Manufacturing and assembly technologies - Assembly and joining processes39 Sheet metal forming Introduction Why do we use sheet metal forming? Sheet metal forming is suitable for almost all manufacturing industries: Examples- 1.The automotive industry uses it to produce heavy- duty body parts such as fenders, hoods and vehicle doors. 2.The food industry uses cans that are made with the help of forming technology. What is sheet metal forming? Sheet metal forming is the manufacturing process of creating the sheet metal components only by deforming the sheet metal and not by breaking, cutting, tearing or removing any part of the sheet. The sheet metal press and like die and punch tools are used for this type of manufacturing process. https://slidetodoc.com/download.php?id=3787338

Manufacturing and assembly technologies - Assembly and joining processes40 Advantages: Same machine can be used for manufacturing different components by changing the dies. Very less wastage. Disadvantages: High equipment and tooling costs; Heat treatment is required afterwards. Ideal applications: Suitable for making mass production of the sheet metal components. Sheet metal forming The form in which sheet metal is found in the market is either in coiled strips or in flat pieces. The coils are made with continuous running of sheet metal into a roll slitter. Usually, the coils used range from 7 to 20 gauges. Solitamente le bobine utilizzate vanno da 7 a 20 calibri. Sheet metal is used in various products like machinery, building roofs, car bodies, airplanes and much more. Sheet Metal Material Used in the Process The common materials used in manufacturing sheet metal are aluminum and stainless steel. The most known grades available in stainless steel are 304, 316 and 410. 304 is one of the most common grades. However, it is not available in the form of a sheet. The other two grades are much resistant and powerful than 304. When it comes to aluminum, it has got four known grades which are 1100-H14, 3003-H14, 5052-H32 and 6061-T6. Every grade is stronger than the other and used in different machinery, weapons and equipment. Introduction

Manufacturing and assembly technologies - Assembly and joining processes 41 What are the types of sheet metal forming processes? 6 Common Sheet Metal Forming Process #1) Bending #2) Curling #3) Roll forming #4) Spinning #5) Deep Drawing #6) Stretch forming 6 Common Sheet Metal Forming Process  Consisting of thin and flat pieces of metal typically steel or aluminum, sheet metal plays an important role in the construction and manufacturing industries.  In the construction industry, it’s used as panels for buildings and houses.  In the manufacturing industry, sheet metal is used for automobile components, heavy machinery, floors and more.  When making sheet metal, however, companies often use one or more of the following forming processes. Sheet metal forming Introduction

Manufacturing and assembly technologies - Assembly and joining processes42 Sheet metal forming #1) Bending  Bending is a common sheet metal forming process.  Companies typically perform bending on sheet metal using either a brake press or similar machine press.  The sheet metal is placed over a die block, at which point a punch presses down onto the sheet metal.  Bending doesn’t actually create holes in sheet metal.  Rather, it lives up to its namesake by “bending” sheet metal in the shape of the die Introduction #2) Curling Curling sheet metal is the process of adding a hollow, circular roll to the edge of the sheet. The curled edge provides strength to the edge and makes it safe for handling. Curling is different than a tear drop hem because in a curl the edge finishes inside itself, where a hem leaves the initial edge exposed #3) Roll Forming  Roll forming is a reliable, proven approach to metal shaping that is ideal for modern applications.  This process uses a continuous bending operation where long metal strips, typically coiled steel, are passed through consecutive sets of rolls at room temperature.  Each set of rolls performs incremental parts of the bend to produce the desired cross- section profile.

Manufacturing and assembly technologies - Assembly and joining processes43 #4) Deep Drawing o Deep drawing is a process in sheet metal forming by the mechanical action of a punch. A flat sheet metal blank is formed over a single, rigid, shape defning tool half by a flexible rubber diaphragm under uniform hydrostatic pressure. o The process results in scratch-free parts regardless of the sheet thickness or complexity of the tool, including undercuts. High forming pressure ensures close tolerance parts direct from the press with little or no secondary hand work required. #5) Stretch Forming  Sheet metal stretch forming processes have very basic mechanisms. Sheet metal workpiece is held by grippers and stretched with tension.  The applied tensile stress on the workpiece is above the yield point of the metal. Because of this fact, the deformation is plastic. Sheet metal forming Introduction #6) Spinning  Metal spinning, also known as spin forming or spinning or metal turning most commonly, is a metalworking process by which a disc or tube of metal is rotated at high speed and formed into an axially symmetric part.  Metal spinning does not involve removal of material, as in conventional wood or metal turning, but forming (moulding) of sheet metal over an existing shape.

https://www.custompartnet.com/wu/sheet-metal-forming#curling https://www.custompartnet.com/wu/sheet-metal-forming#bending https://www.iqsdirectory.com/articles/roll-forming.html https://www.custompartnet.com/wu/sheet-metal-forming#spinning https://www.custompartnet.com/wu/sheet-metal-forming#deep_drawing https://www.custompartnet.com/wu/sheet-metal-forming#stretch_forming Manufacturing and assembly technologies - Assembly and joining processes44bi s

Manufacturing and assembly technologies - Assembly and joining processes6 Sheet metal forming Types of sheet metal forming processes - #1) Bending  Bending is a metal forming process in which a force is applied to a piece of sheet metal, causing it to bend at an angle and form the desired shape.  A bending operation causes deformation along one axis, but a sequence of several different operations can be performed to create a complex part.  Bent parts can be quite small, such as a bracket, or up to 20 feet in length, such as a large enclosure or chassis.  A bend can be characterized by several different parameters, shown in the image. Bending Diagram

Types of sheet metal forming processes - #1) Bending Sheet metal forming 1)Bend line - The straight line on the surface of the sheet, on either side of the bend, that defines the end of the level flange and the start of the bend. 2)Outside mold line - The straight line where the outside surfaces of the two flanges would meet, were they to continue. This line defines the edge of a mold that would bound the bent sheet metal. 3)Flange length - The length of either of the two flanges, extending from the edge of the sheet to the bend line. 4)Mold line distance - The distance from either end of the sheet to the outside mold line. 5)Setback - The distance from either bend line to the outside mold line. Also equal to the difference between the mold line distance and the flange length. 6)Bend axis - The straight line that defines the center around which the sheet metal is bent. 7)Bend length - The length of the bend, measured along the bend axis. 8)Bend radius - The distance from the bend axis to the inside surface of the material, between the bend lines. Sometimes specified as the inside bend radius. The outside bend radius is equal to the inside bend radius plus the sheet thickness. 9)Bend angle - The angle of the bend, measured between the bent flange and its original position, or as the included angle between perpendicular lines drawn from the bend lines. 10)Bevel angle - The complimentary angle to the bend angle Manufacturing and assembly technologies - Assembly and joining processes7

8 Types of sheet metal forming processes - #1) Bending Sheet metal forming Manufacturing and assembly technologies - Assembly and joining processes The act of bending results in both tension and compression in the sheet metal. The outside portion of the sheet will undergo tension and stretch to a greater length, while the inside portion experiences compression and shortens. The neutral axis is the boundary line inside the sheet metal, along which no tension or compression forces are present. As a result, the length of this axis remains constant. The changes in length to the outside and inside surfaces can be related to the original flat length by two parameters, the bend allowance and bend deduction, which are defined below Neutral Axis

Manufacturing and assembly technologies - Assembly and joining processes9 Types of sheet metal forming processes - #1) Bending Sheet metal forming Neutral axis - The location in the sheet that is neither stretched nor compressed, and therefore remains at a constant length. K-factor - The location of the neutral axis in the material, calculated as the ratio of the distance of the neutral axis (measured from the inside bend surface) to the material thickness. The K-factor is dependent upon several factors (material, bending operation, bend angle, etc.) and is typically greater than 0.25, but cannot exceed 0.50. Bend allowance - The length of the neutral axis between the bend lines, or in other words, the arc length of the bend. The bend allowance added to the flange lengths is equal to the total flat length. Bend deduction - Also called the bend compensation, the amount a piece of material has been stretched by bending. The value equals the difference between the mold line lengths and the total flat length.

Manufacturing and assembly technologies - Assembly and joining processes10 Types of sheet metal forming processes - #1) Bending Sheet metal forming When bending a piece of sheet metal, the residual stresses in the material will cause the sheet to springback slightly after the bending operation. Due to this elastic recovery, it is necessary to over-bend the sheet a precise amount to achieve the desired bend radius and bend angle. The final bend radius will be greater than initially formed and the final bend angle will be smaller. The ratio of the final bend angle to the initial bend angle is defined as the springback factor, K S. The amount of springback depends upon several factors, including the material, bending operation, and the initial bend angle and bend radius. springback

Manufacturing and assembly technologies - Assembly and joining processes12 Types of sheet metal forming processes - #1) Bending Sheet metal forming Bending is typically performed on a machine called a press brake, which can be manually or automatically operated. For this reason, the bending process is sometimes referred to as press brake forming. Press brakes are available in a range of sizes (commonly 20-200 tons) in order to best suit the given application. A press brake contains an upper tool called the punch and a lower tool called the die, between which the sheet metal is located. The sheet is carefully positioned over the die and held in place by the back gauge while the punch lowers and forces the sheet to bend. In an automatic machine, the punch is forced into the sheet under the power of a hydraulic ram. Press Brake (Open) A punch is a tool that is forced into a piece of sheet metal in order to shear or deform the material. Punches are available in many shapes and sizes and can be used for a variety of processes. Many punches are cylindrical and the punch diameter determines the size of the hole or pocket being formed. In shearing processes (blanking or punching), the punch has a square edge to shear the material. In forming processes (bending or deep drawing), the punch has an edge radius.

Manufacturing and assembly technologies - Assembly and joining processes13 The bend angle achieved is determined by the depth to which the punch forces the sheet into the die. This depth is precisely controlled to achieve the desired bend. Standard tooling is often used for the punch and die, allowing a low initial cost and suitability for low volume production. Custom tooling can be used for specialized bending operations but will add to the cost. The tooling material is chosen based upon the production quantity, sheet metal material, and degree of bending. Naturally, a stronger tool is required to endure larger quantities, harder sheet metal, and severe bending operations. In order of increasing strength, some common tooling materials include hardwood, low carbon steel, tool steel, and carbide steel. Types of sheet metal forming processes - #1) Bending Sheet metal forming Press Brake (Closed)

Manufacturing and assembly technologies - Assembly and joining processes52 Types of sheet metal forming processes - #1) Bending Sheet metal forming While using a press brake and standard die sets, there are still a variety of techniques that can be used to bend the sheet. The most common method is known as V-bending, in which the punch and die are "V" shaped. The punch pushes the sheet into the "V" shaped groove in the V-die, causing it to bend. If the punch does not force the sheet to the bottom of the die cavity, leaving space or air underneath, it is called "air bending". As a result, the V-groove must have a sharper angle than the angle being formed in the sheet. If the punch forces the sheet to the bottom of the die cavity, it is called "bottoming". This technique allows for more control over the angle because there is less springback. However, a higher tonnage press is required. In both techniques, the width of the "V" shaped groove, or die opening, is typically 6 to 18 times the sheet thickness. This value is referred to as the die ratio and is equal to the die opening divided by the sheet thickness. V Bending

53 Spring back In bending, residual stresses cause the material to spring back slightly after the bending operation. Due to this elastic recovery, it is necessary to over-bend a precise amount to achieve the desired bend radius and bend angle. The final bend radius will be greater than initially formed and the final bend angle will be smaller. The ratio of the final bend angle to the initial bend angle is defined as the springback factor, Ks. The amount of springback depends upon several factors, including the material, bending operation, and the initial bend angle and bend radius. Manufacturing and assembly technologies - Assembly and joining processes53 Types of sheet metal forming processes - #1) Bending Sheet metal forming V Bending

Manufacturing and assembly technologies - Assembly and joining processes54 Types of sheet metal forming processes - #1) Bending Sheet metal forming Wipe Bending In addition to V-bending, another common bending method is wipe bending, sometimes called edge bending. Wipe bending requires the sheet to be held against the wipe die by a pressure pad. The punch then presses against the edge of the sheet that extends beyond the die and pad. The sheet will bend against the radius of the edge of the wipe die.

Sheet metal forming Types of sheet metal forming processes - #1) Bending Manufacturing and assembly technologies - Assembly and joining processes17 Design rules Bend location - A bend should be located where enough material is present, and preferably with straight edges, for the sheet to be secured without slipping. The width of this flange should be equal to at least 4 times the sheet thickness plus the bend radius. Bend radius - The radius of a bend in a piece of material that occurs between the bend lines. The radius is measured from the bend axis to the inside surface of the material and is therefore sometimes specified as the inside bend radius. The bend radius is typically equal to at least the sheet thicknes o Use a single bend radius for all bends to eliminate additional tooling or setups o Inside bend radius should equal at least the sheet thickness Bend direction - Bending hard metals parallel to the rolling direction of the sheet may lead to fracture. Bending perpendicular to the rolling direction is recommended. Any features, such as holes or slots, located too close to a bend may be distorted. The distance of such features from the bend should be equal to at least 3 times the sheet thickness plus the bending radius. In the case of manual bending, if the design allows, a slot can be cut along the bend line to reduce the manual force required.

Sheet metal forming Manufacturing and assembly technologies - Assembly and joining processes18 Types of sheet metal forming processes - #2) Curling Curling sheet metal is the process of adding a hollow, circular roll to the edge of the sheet. The curled edge provides strength to the edge and makes it safe for handling. Curling is different than a tear drop hem because in a curl the edge finishes inside itself, where a hem leaves the initial edge exposed. Sheet Metal HemsSheet Metal Hems are formed using very different methods, though produces features with similar uses and functionality. Curls are most often used to remove a sharp untreated edge and make it safe for handling. Curls come in two basic forms, off center and on center rolls. Off center rolls have the center of the roll above the original plane of the sheet metal. On center rolls will have the center of the roll in line with the plane of the sheet metal.

Sheet metal forming Manufacturing and assembly technologies - Assembly and joining processes20 Types of sheet metal forming processes - #2) Curling Forming A Sheet Metal Curl How a curl is formed depends entirely on the type of machinery you wish to use. Curls can be fabricated through roll forming, stamping, leaf bending, and on a traditional press brake. Each machine will have its own set of tooling for achieving the curl. Here we will be discussing the fabrication and tooling methods for forming on a leaf bender and press brake.

Sheet metal forming Manufacturing and assembly technologies - Assembly and joining processes21 Types of sheet metal forming processes - #2) Curling Forming a Curl on a Panel Bender Curling on a panel or leaf bender is often limited to off center curls because most panel benders do not have tooling profiles which can create the necessary down bend to put the curl on center. Off center rolls however are very easily formed on this type of machine. The desired radius is created by Step Bending a progressively larger radius into the sheet, beginning with the desired curl radius minus the material thickness, and ending with the desired curl radius. Step Bending The smaller radius is formed first to allow the material to finish inside itself. The process of step bending involves producing very small bends in very close to each other, and while the finished bend is technically a polygon, it’s often impossible to detect the steps if they are formed correctly. For lighter gauges a hand operated panel bender can be the most affordable method for creating a curl.

Manufacturing and assembly technologies - Assembly and joining processes22 Sheet metal forming Types of sheet metal forming processes - #2) Curling  Forming a Curl on a Brake Press  To curl sheet metal on a Brake Press specialized tooling is required. Most curls are formed in three stages and some setups require two tooling setups with specialized tooling for each stage.  The first 2 stages form the curves required to form the curl, and the third stage closes the curl.  A locating notch is typical for this type of tooling to ensure that the first and second stages are bent in the correct location.  Below is a typical two setup, three stage tooling.  Because of this the tooling is typically unbalanced, meaning the tonnage isn’t evenly distributed front to back, so stabilizing features are sometimes incorporated.  When a stabilizing bar is used it allows for the two stages to be combined into one set of tooling. Below is an example of a one setup, three stage tooling.

Sheet metal forming Types of sheet metal forming processes - #3) Roll forming Manufacturing and assembly technologies - Assembly and joining processes23 https://www.iqsdirectory.com/articles/roll-forming.html Roll Forming We will learn: What is roll forming Roll forming processes Technical advances in roll forming The benefits and advantages Metals that can be roll formed And much more

Sheet metal forming Types of sheet metal forming processes - #2) Roll forming process Manufacturing and assembly technologies - Assembly and joining processes24 What is roll forming? Roll forming is a process that uses a set of precisely placed rollers to perform incremental bending to a continuously fed strip of metal. The rollers are mounted in sets on a consecutive stand with each roller completing one small step of the process. Rollers are carefully crafted using a flower pattern, which identifies the sequential changes to the metal strip. The shape of each roller is created from the individual sections of the flower pattern. Each of the colors in the above flower pattern illustrates one of the incremental bends used to complete the part. The individual colors are a single bending operation.

Manufacturing and assembly technologies - Assembly and joining processes25 Sheet metal forming Types of sheet metal forming processes - #2) Roll forming Roll Forming Process Each roll forming manufacturer has a different set of steps for their roll forming process. Regardless of the variations, there are a set of basic steps all producers use. The process begins with a large coil of sheet metal that can be from 1 inch to 30 inches wide with a thickness of 0.012 inch to 0.2 inch. Before a coil can be loaded, it has to be prepared for the process. The diagram represents each step of roll forming from the feeding of the coil to the cutoff and discharge at the end of the process. Below is a description of each step.

Manufacturing and assembly technologies - Assembly and joining processes26 Sheet metal forming Types of sheet metal forming processes - #2) Roll forming 1.Uncoiling: Metal coils may become set during storage and have a tendency to stay coiled and become distorted. To correct the problem, the coil is loaded onto the uncoiler, seen below, and fed through a flattener to remove the coil set. The lead end is trimmed to allow for smooth feeding into the pre-press process. Part of the pre-press operation may be a tapering of the beginning of the feed coil to make it easier for it to slide into the forming rollers. Steps of the Roll Forming Process

Manufacturing and assembly technologies - Assembly and joining processes27 Sheet metal forming Types of sheet metal forming processes - #2) Roll forming 2.Pre-press treatment: Before the metal from the coil is fed into the roll forming rollers, it may need applications added as can be seen in the image below, which can involve adding slots, holes, or slits.

Manufacturing and assembly technologies - Assembly and joining processes28 Sheet metal forming Types of sheet metal forming processes - #2) Roll forming 3. Roll forming At this stage, the material is progressively shaped. A typical roll forming machine can consist of 10 to 24 pairs of roller die stands. The machine is individually or gang driven to force the ribbon of metal through the rollers that gradually shape it to the dimensions of the flower pattern.

Manufacturing and assembly technologies - Assembly and joining processes29 Sheet metal forming Types of sheet metal forming processes - #2) Roll forming 4. Cutoff and discharge: Parts are cut to length as they are in motion, which increases the efficiency and speed of the roll forming process. Once they are cut, they are discharged to a run-out table to be placed for shipment or further processing.

Manufacturing and assembly technologies - Assembly and joining processes30 Sheet metal forming Types of sheet metal forming processes - #2) Roll forming 5. Secondary processes: There are a variety of ways secondary processes can be performed. Some can be completed as the part comes off the cutoff, while others may have to be performed at another station. The image below has samples of some of the listed secondary processes, which include: Punching Notching Tight tolerance forming Straightening Adding other components Minor assembly

Manufacturing and assembly technologies - Assembly and joining processes31 Sheet metal forming Types of sheet metal forming processes - #2) Roll forming Lubricant With any metal forming process, friction plays an important role, which is the resistance produced when two bodies make contact. It is a means of energy dissipating that causes a rise in temperature where two surfaces meet. The temperature is further enhanced by the speed of the process. Lubrication is used in the roll forming process to reduce friction between the rolls and metal to prevent tool wear. Friction is a necessary part of the rolling process and an important part of shifting the metal forward between the rollers. It should not be eliminated or reduced below an appropriate level. The need for friction has to be considered when choosing a lubricant.

Manufacturing and assembly technologies - Assembly and joining processes32 Sheet metal forming Types of sheet metal forming processes - #2) Roll forming Roll forming uses fluid lubricants with a low viscosity that include paraffin for non-ferrous metals such as aluminum and copper. Lubricants increase the rate of production, which is determined by the thickness of the material, number of roll stations, and the amount of bending. Below is an example of a roll forming process that uses a chlorine free lubricant.

Manufacturing and assembly technologies - Assembly and joining processes33 Sheet metal forming Types of sheet metal forming processes - #2) Roll forming Technical Advances in Roll Forming Technological advances have had a significant impact on the roll forming industry. The methods and processes from computerization has improved dimensional accuracy and adherence to tolerances. Below is a description of a few of the significant improvements. Computer Numerically Control (CNC) A CNC machine can be programmed to control metal processing and give instructions to automatic tools, equipment, and rollers. They decide the sequence of machine operations, perform trial runs, and can be programmed with specific part geometries to follow the flower pattern.

Manufacturing and assembly technologies - Assembly and joining processes34 Sheet metal forming Types of sheet metal forming processes - #2) Roll forming Computer Aided Design (CAD) or Manufacturing (CAN) Designing for roll forming involves three engineering design elements: geometry, length, and type of material. The designs created in CAD/CAM can be easily transferred to CNC programming. Geometry - Roll forming can use CAD to reduce complex, multiple component parts into a single structure. Several simple components can be combined to form a single complex shape. Length – Roll forming is ideal for long parts with high production runs. Stamped and press braked parts can be converted to roll forming using CAD programming

Manufacturing and assembly technologies - Assembly and joining processes72 Sheet metal forming Sensing Technologies in Metal Forming The sensing technologies used in metal-forming processes can be divided into four categories: 1.direct and indirect metrologies with commercial sensors 2.the development of particular sensors or sensing systems, such as die- embedded sensors, and 3.intelligent metrologies associated with soft sensing. Some case studies on direct and indirect metrologies with commercial sensors and the development of die-embedded sensors will be introduced. Intelligent metrologies associated with soft sensing will be introduced in the next section. https://myukk.org/SM2017/sm_pdf/SM1998.pdf

Manufacturing and assembly technologies - Assembly and joining processes16 Sheet metal forming Sensing Technologies in Metal Forming Process sensing by direct metrology Typical process monitoring technologies used in metal forming are the measurement of the punch force using a load cell located under the punch and the measurement of the punch stroke using displacement transducers. These are examples of direct measurements by which one can easily obtain information on the deformation resistance of a material and other process states, such as lubrication. A smart die system has been developed for a blanking process by using a compact load cell embedded in a die, which is placed directly under the punch to detect abnormal phenomena, such as blank beating, clogging, and damage to the die, and to provide feedback to the press machine to stop the process on an actual production line. It is also possible to obtain information on the wear of dies from a continuously measured load waveform during processing in the same manner as described above by extracting and comparing features using an AI inference tool. As a result, the life of a die can be predicted from load information obtained by recording the load waveform during punching and comparing it with the initial waveform.

Manufacturing and assembly technologies - Assembly and joining processes17 Sheet metal forming Sensing Technologies in Metal Forming HIGH END PROCESS MONITORING FOR METAL FORMING AND SHEET METAL FORMING The X7 is an in-process monitoring system for metal forming processes such as cold, warm and hot forming, form and thread rolling as well as the entire field of sheet metal forming. The system allows the monitoring of various machines and sensors and with different types of monitoring methods. It is modular and can be equipped with a flexible number of inputs for analog (1 - 24) or binary sensors (4 - 20). The 15 inch display provides a clearly structured user interface with touch screen operation. The X7 expert system makes device set-up easier and helps the operator to quickly and easily adapt to different monitoring tasks. Third-party programs for displaying DC masks, graphics, failure images, etc., can be run on the X7 Windows 8.1 frontend. https://www.marposs.com/eng/product/high -end-process-monitoring-for-forming

Manufacturing and assembly technologies - Assembly and joining processes75 Sheet metal forming Sheet Metal bending is an effective way of making products with different shapes used for different processes. It guarantees simplicity and it is an efficient way of forming new products. Here, you will know about sheet metal bending, its importance, and the methods needed for the process. What is Sheet Metal Bending? Sheet metal bending is an operation that involves using forces to change the shape of a sheet. This is done to achieve the desired form or shape needed for a manufacturing process. The external force used alters only the external features of the sheet. However, parameters of the sheet metal such as length and thickness remain the same. The malleability of the sheet metal further allows it to undergo various shaping processes. Types of sheet metal forming processes - #2) Bending

Sheet metal forming Sheet metal bending is one of the essential procedures in the metal processing industry. For example, it is an important phase in the automotive companies since they work with different shapes to get the perfect automobile part that works with their design. The process can be at an industrial level, where it is ideal for creating big engine parts. Nevertheless, it can also be used in making little parts for the replacement of worn-out engine parts. While there are many processes involved in the operation, all sheet metal bending methods consider standard techniques to ensure precision across its production. Types of sheet metal forming processes - #2) Bending Manufacturing and assembly technologies - Assembly and joining processes19

Sheet metal forming Sheet Metal Bending Methods Sheet metal bending methods are similar in that their end goal which is to transform sheet metals’ structures to the desired forms. However, they differ in operation. Knowing how to bend sheet metal comes with understanding that factors such as the thickness of the material, size of the bend, sheet metal bend radius, and intended purpose determine the methods. The methods listed below would not only show you how to bend sheet metal. They would also show you which to employ for the best outcome. The most common sheet metal bending methods are: Types of sheet metal forming processes - #2) Bending Manufacturing and assembly technologies - Assembly and joining processes20

Sheet metal forming This is the most common sheet bending method as it is used for most bending projects. It employs an instrument known as the punch and v-die to bend sheet metals at desired angles. During the process, the bending punch presses on the sheet metal placed over the V-die. The angle formed by the sheet metal is dependent on the pressure point of the punch. This makes this method easy and efficient as it can be employed for bending steel plates without altering their position. The V-bending method can be classified into three: Air Bending Bottoming Coining Types of sheet metal forming processes - #2) Bending Manufacturing and assembly technologies - Assembly and joining processes21

Sheet metal forming  As the name suggests, bottoming or bottom bending involves compressing the sheet metal to the preset die’s bottom to form a defined angle and shape.  In bottoming, the position and shape of the die angle determine the outcome of the bend.  Also, the spring-back of the compressed sheet metal is impossible.  This is because the force of the punch and the die’s angle conforms the sheet metal to a permanent structure. Bottoming Types of sheet metal forming processes - #2) Bending Manufacturing and assembly technologies - Assembly and joining processes22

Manufacturing and assembly technologies - Assembly and joining processes80 Sheet metal forming Coining  Coining is a bending method widely employed for its precision and its unique ability to create distinguishing sheets.  In the process, there is no spring-back of the sheets.  This is because the coin penetrates the sheet metal at a small radius, creating a dent present on a coin to distinguish sheets from another Types of sheet metal forming processes - #2) Bending

Sheet metal forming Air bending or partial bending is a less accurate method compared to bottoming and coining. However, it is usually employed for its simplicity and ease of manipulation since it doesn’t require tools. There is also a disadvantage. Air bending is the only method prone to the springback of the sheet metal. In air bending, the punch exerts a force on the sheet metal resting on both points of the die’s opening. A press brake is usually employed during the V bending as the sheet metal does not come in contact with the bottom of the die Air Bending Types of sheet metal forming processes - #2) Bending Manufacturing and assembly technologies - Assembly and joining processes24

Sheet metal forming Roll bending is a method used to bend sheet metals into rolls or curved shapes. The process employs a hydraulic press, a press brake, and three sets of rollers to make different bends or a big round the bend. It is useful in forming cones, tubes, and hollow shapes as it takes advantage of the distance between its rollers to make bends and curves. U-Bending, in terms of principle, is akin to V- bending. It uses the same instrument (except a U-die) and process, although the only difference is that the shape formed is U-shaped. U-bending is very popular. However, other methods produce the shape flexibly. Types of sheet metal forming processes - #2) Bending Manufacturing and assembly technologies - Assembly and joining processes 25

Sheet metal forming #2) Rotary Bending This bending method has an advantage over wipe bending or V-bending because it does not lead to scratching the material’s surface. It is also ideal because it can bend materials into sharp corners. For example, it is used in bending corners greater than 90 0. Manufacturing and assembly technologies - Assembly and joining processes 26

Manufacturing and assembly technologies - Assembly and joining processes 84 Sheet metal forming Introduction

Manufacturing and assembly technologies - Assembly and joining processes85 #3 Ironing Sheet metal forming Sheet Metal Forming Process - Ironing

A typical car body has about 440 sheet metal parts made by forming  Sheet metals can be bent or stretched into a variety of complex shapes, permitting the creation of complex structures with great strength and a minimum amount of material. Manufacturing and assembly technologies - Assembly and joining processes86  Metal manufacturing is essential for all areas of the economy. Because of their strength, stiffness, and long-term durability, metal components are used in applications from appliances to construction parts and car body panels.  Traditional metal manufacturing techniques include forming, casting, molding, joining, and machining.  Sheet metal forming involves various processes where force is applied to a piece of sheet metal to plastically deform the material into the desired shape, modifying its geometry rather than removing any material. Sheet metal forming Introduction (1/2)

Manufacturing and assembly technologies - Assembly and joining processes87Manufacturing and assembly technologies - Assembly and joining processes87 Sheet metal forming 6 Commons Sheet Metal Forming Process Consisting of thin and flat pieces of metal — typically steel or aluminum — sheet metal plays an important role in the construction and manufacturing industries. 1.In the construction industry, it’s used as panels for buildings and houses. 2.In the manufacturing industry, sheet metal is used for automobile components, heavy machinery, floors and more. When making sheet metal, however, companies often use one or more of the following forming processes. #1) Curling #2) Bending #3) Ironing #4) Laser Cutting #5) Hydroforming #6) Punching

Manufacturing and assembly technologies - Assembly and joining processes88Manufacturing and assembly technologies - Assembly and joining processes Sheet metal forming Two examples of curling... Curling gives stiffness to the workpiece by increasing the moment of inertia at the ends, and providing smooth rounded edges. 1.In the first example, the edge of the sheet metal into the cavity of punch 2.In the second example, the circular edge of the initial deep-drawn workpiece is curled by a tool that incorporates a cavity punch. Curling process Circular edge curling. fig. 1 fig. 2

Manufacturing and assembly technologies - Assembly and joining processes89 Sheet metal forming The curling force is given by the equation: where: M=moment of bending R=inside curling radius T=material thicknesss Example: Define the curling force for the workpiece shown in figure. Assume Diameter D = 400 mm, Material thickness T = 1.2 mm, Inner radius R i = 1.2 mm, The ultimate tensile strength UTS = 176 Solution:

Manufacturing and assembly technologies - Assembly and joining processes90 Sheet metal forming Known bend and curl forces often are not so important for the process because very often, the maximum force of the press machine is greater than the bending or curling force. However, knowing the magnitude of these forces is necessary for a definition of the blank-holder forces. Because of the phenomenon of material fatigue of the blank springs, these forces need to be 30 to 50 percent greater than the bending or the curling forces

Manufacturing and assembly technologies - Assembly and joining processes91 Sheet metal forming Sheet metal forming processes Introduction Products made of sheet metals are all around us. They include a very wide range of consumer and industrial products, such as beverage cans, cookware, file cabinets, metal desks, appliances, car bodies (see figures). The term pressworking or press forming is used commonly in industry to describe general sheet-forming operations, because they typically are performed on presses. Some sheet metal applications

Manufacturing and assembly technologies - Assembly and joining processes92 Sheet metal forming Sheet metal forming processes Material in sheet metal forming processes:  Low-carbon steel is the most commonly used sheet metal because of its low cost and generally good strength and formability characteristics.  Aluminum is the most common material for such sheet-metal applications as beverage cans, packaging, kitchen utensils, and applications where corrosion resistance is a concern.  The common metallic materials for aircraft and aerospace applications are aluminum and titanium Temperature and sheet metal forming:  Most manufacturing processes involving sheet metal are performed at room temperature.  Hot stamping is occasionally performed in order to increase formability and decrease forming loads on machinery.  Typical materials in hot stamping operations are titanium alloys and various high strength steels.

Figure Basic sheet metalworking operations: (a)bending, (b)drawing, and (c)Shearing; (1)as punch first contacts sheet and (2)after cutting. (3)Force and relative motion are indicated by F and v Manufacturing and assembly technologies - Assembly and joining processes93 Sheet metal forming Sheet metal forming processes Types of metal forming operations: (1/4) The three major categories of sheet-metal processes are (1) cutting, (2) bending and (3) drawing as shown in figure. a.Cutting is used to separate large sheets into smaller pieces, to cut out part perimeters, and to make holes in parts. b.Bending and drawing are used to form sheet-metal parts into their required shapes.

Manufacturing and assembly technologies - Assembly and joining processes94 Sheet metal forming Cutting operations: The three most important operations in pressworking that cut metal by the shearing mechanism just described are shearing, blanking, and punching. A) Shearing: Shearing is a sheet metal cutting operation along a straight line between two cut-ting edges by means of a power shear see figure Figure show the shearing operation and its equipment

Manufacturing and assembly technologies - Assembly and joining processes95 Sheet metal forming B) Blanking and punching Blanking and punching are similar sheet metals cutting operations that involve cutting the sheet metal along a closed outline. If the part that is cut out is the desired product, the operation is called blanking and the product is called blank. If the remaining stock is the desired part, the operation is called punching as shown in figure. Both operations are illustrated on the example of producing a washer: Figure shows the blanking and punching operations

Manufacturing and assembly technologies - Assembly and joining processes97 Sheet metal forming C) Bending operation: Bending in sheet-metalwork is defined as the straining of the metal around a straight axis, as in Figure Figure show bending of sheet metal Bending operations are performed using punch and die tooling. The two common bending methods and associated tooling are V-bending, performed with a V-die; and edge bending, performed with a wiping die. These methods are illustrated in Figure Figure: types of bending operations

Manufacturing and assembly technologies - Assembly and joining processes98 Sheet metal forming In V-bending, the sheet metal is bent between a V-shaped punch and die. Included angles ranging from very obtuse to very acute can be made with V- dies. It is often performed on a press brake, and the associated V-dies are relatively simple and inexpensive. Edge bending involves cantilever loading of the sheet metal. A pressure pad is used to apply a force to hold the base of the part against the die, while the punch forces the part to yield and bend over the edge of the die. In the setup shown in Figure (right), edge bending is limited to bends of 90 ◦ or less. More complicated wiping dies can be designed for bend angles greater than 90 ◦. Because of the pressure pad, wiping dies are more complicated and costly than V-dies and are generally used for high-production work.

Manufacturing and assembly technologies - Assembly and joining processes99 Sheet metal forming D) Springback When the bending pressure is removed at the end of the deformation operation, elastic energy remains in the bent part, causing it to recover partially toward its original shape. This elastic recovery is called springback, defined as the increase in included angle of the bent part relative to the included angle of the forming tool after the tool is removed. This is illustrated in Figure Compensation for springback can be accomplished by several methods. Two common methods are overbending and bottoming.

Manufacturing and assembly technologies - Assembly and joining processes100  Sheet metal forming is the most cost-effective forming procedure today for manufacturing parts in large quantities.  It can be highly automated in factories or, at the other end of the spectrum, manually operated in metal workshops for small series parts. Sheet metal forming Introduction (2/2) A typical car body has about 440 sheet metal parts made by forming  It is a versatile, consistent, and high-quality procedure to create accurate metal parts with limited material waste.

Sheet metal forming Sheet Metal Basics  Sheet metal refers to thin, flat metal pieces that are formed by industrial processes.  These can be extremely thin sheets, considered foil or leaf, to up to 6 mm (0.25 in) sheets.  Pieces thicker than 6 mm are considered plate steel or "structural steel.”  Sheet metal thickness is normally specified in millimeters around the world, while the US uses a non-linear measure known as the gauge.  The larger the gauge number, the thinner the metal sheet. A sheet metal blank for forming a blade guard for an electric saw.  Plate metal is generally used in applications where durability is more important than weight, for example in larger structural parts of ships, pressure vessels, and turbines.  Many different metals can be processed into sheet metal, including aluminum, steel, brass, tin, copper, nickel, titanium, and for decorative purposes, also gold, silver, and platinum.  Sheet metal work stock is normally rolled and comes in coils that can be cut and bent into a variety of shapes.  Sheet metal is widely used in the manufacturing of cars, aircraft, trains, hardware enclosures, office tools, furniture, house appliances, computers, machine components, beverage cans, and in construction (ducts, gutters, etc.). 101Manufacturing and assembly technologies - Assembly and joining processes

Definition and General Information Forming is usually carried out with special electronically controlled machines such as presses, bending machines and steam hammers. In accordance with the integrated tool, many of them are suitable for multiple manufacturing processes. The most common materials used in sheet metal forming are steel, copper, aluminum, aluminum alloys and copper alloys (wrought alloys). A distinction is made according to  the temperatures that occur between cold forming, warm forming and hot forming  the type of workpiece between sheet metal forming and massive forming  the type of mechanical stress in accordance with DIN 8582  tensile forming (lengths, depths, widths)  pressure forming (free forming, rolling)  tensile compression forming (deep drawing)  hear forming (shifting, twisting)  Bending (edging, free bending, swivel bending) In addition, there are also special processes for sheet metal forming such as press hardening and flexforming. For sheet metal forming, level sheets are usually used, which are usually machined by cold forming. Sheet metal forming 102Manufacturing and assembly technologies - Assembly and joining processes

Sheet metal forming Definition and General Information Sheet metal forming processes are those in which force is applied to a piece of sheet metal to modify its geometry rather than remove any material. The applied force stresses the metal beyond its yield strength causing the material to plastically deform, but not to fail. Yield strength is the maximum stress that can be applied before it begins to change shape permanently. This is an approximation of the elastic limit of the steel. If stress is added to the metal but does not reach the yield point, it will return to its original shape after the stress is removed. By doing so, the sheet can be bent or stretched into a variety of complex shapes. Sheet metal forming processes include the following:  Bending  Roll forming  Spinning  Deep Drawing  Stretch forming Manufacturing and assembly technologies - Assembly and joining processes103

Sheet metal forming Bending Bending Diagram  Bending is a metal forming process in which a force is applied to a piece of sheet metal, causing it to bend at an angle and form the desired shape.  A bending operation causes deformation along one axis, but a sequence of several different operations can be performed to create a complex part.  Bent parts can be quite small, such as a bracket, or up to 20 feet in length, such as a large enclosure or chassis.  A bend can be characterized by several different parameters, shown in the image below. Manufacturing and assembly technologies - Assembly and joining processes104

Bending Bend line - The straight line on the surface of the sheet, on either side of the bend, that defines the end of the level flange and the start of the bend. Outside mold line - The straight line where the outside surfaces of the two flanges would meet, were they to continue. This line defines the edge of a mold that would bound the bent sheet metal. Flange length - The length of either of the two flanges, extending from the edge of the sheet to the bend line. Sheet metal forming Manufacturing and assembly technologies - Assembly and joining processes105

Sheet metal forming Bending Mold line distance - The distance from either end of the sheet to the outside mold line. Setback - The distance from either bend line to the outside mold line. Also equal to the difference between the mold line distance and the flange length. Bend axis - The straight line that defines the center around which the sheet metal is bent. Bend length - The length of the bend, measured along the bend axis. Manufacturing and assembly technologies - Assembly and joining processes106

Bending Diagram Bend radius - The distance from the bend axis to the inside surface of the material, between the bend lines. Sometimes specified as the inside bend radius. The outside bend radius is equal to the inside bend radius plus the sheet thickness. Bend angle - The angle of the bend, measured between the bent flange and its original position, or as the included angle between perpendicular lines drawn from the bend lines. Bevel angle - The complimentary angle to the bend angle. Manufacturing and assembly technologies - Assembly and joining processes107 Sheet metal forming Bending

Sheet metal forming Bending The act of bending results in both tension and compression in the sheet metal. The outside portion of the sheet will undergo tension and stretch to a greater length, while the inside portion experiences compression and shortens. The neutral axis is the boundary line inside the sheet metal, along which no tension or compression forces are present. As a result, the length of this axis remains constant. The changes in length to the outside and inside surfaces can be related to the original flat length by two parameters, the bend allowance and bend deduction, which are defined below. Neutral Axis Manufacturing and assembly technologies - Assembly and joining processes108

Sheet metal forming Neutral axis - The location in the sheet that is neither stretched nor compressed, and therefore remains at a constant length. K-factor - The location of the neutral axis in the material, calculated as the ratio of the distance of the neutral axis (measured from the inside bend surface) to the material thickness. The K-factor is dependent upon several factors (material, bending operation, bend angle, etc.) and is typically greater than 0.25, but cannot exceed 0.50. Bend allowance - The length of the neutral axis between the bend lines, or in other words, the arc length of the bend. The bend allowance added to the flange lengths is equal to the total flat length. Bend deduction - Also called the bend compensation, the amount a piece of material has been stretched by bending. The value equals the difference between the mold line lengths and the total flat length. Manufacturing and assembly technologies - Assembly and joining processes109

When bending a piece of sheet metal, the residual stresses in the material will cause the sheet to springback slightly after the bending operation. Due to this elastic recovery, it is necessary to over-bend the sheet a precise amount to achieve the desired bend radius and bend angle. The final bend radius will be greater than initially formed and the final bend angle will be smaller. The ratio of the final bend angle to the initial bend angle is defined as the springback factor, KS. The amount of springback depends upon several factors, including the material, bending operation, and the initial bend angle and bend radius. Sheet metal forming Springback https://www.custompartnet.co m/wu/sheet-metal-forming Manufacturing and assembly technologies - Assembly and joining processes110

Bending is typically performed on a machine called a press brake, which can be manually or automatically operated. For this reason, the bending process is sometimes referred to as press brake forming. Press brakes are available in a range of sizes (commonly 20-200 tons) in order to best suit the given application. A press brake contains an upper tool called the punch and a lower tool called the die, between which the sheet metal is located. The sheet is carefully positioned over the die and held in place by the back gauge while the punch lowers and forces the sheet to bend. In an automatic machine, the punch is forced into the sheet under the power of a hydraulic ram. The bend angle achieved is determined by the depth to which the punch forces the sheet into the die. This depth is precisely controlled to achieve the desired bend. Standard tooling is often used for the punch and die, allowing a low initial cost and suitability for low volume production. Sheet metal forming Manufacturing and assembly technologies - Assembly and joining processes111

Custom tooling can be used for specialized bending operations but will add to the cost. The tooling material is chosen based upon the production quantity, sheet metal material, and degree of bending. Naturally, a stronger tool is required to endure larger quantities, harder sheet metal, and severe bending operations. In order of increasing strength, some common tooling materials include hardwood, low carbon steel, tool steel, and carbide steel. Sheet metal forming Press Brake (Open)Press Brake (Closed) Manufacturing and assembly technologies - Assembly and joining processes112

Sheet metal forming While using a press brake and standard die sets, there are still a variety of techniques that can be used to bend the sheet. The most common method is known as V-bending, in which the punch and die are "V" shaped. The punch pushes the sheet into the "V" shaped groove in the V-die, causing it to bend. If the punch does not force the sheet to the bottom of the die cavity, leaving space or air underneath, it is called "air bending". As a result, the V-groove must have a sharper angle than the angle being formed in the sheet. If the punch forces the sheet to the bottom of the die cavity, it is called "bottoming". This technique allows for more control over the angle because there is less springback. However, a higher tonnage press is required. In both techniques, the width of the "V" shaped groove, or die opening, is typically 6 to 18 times the sheet thickness. This value is referred to as the die ratio and is equal to the die opening divided by the sheet thickness. Manufacturing and assembly technologies - Assembly and joining processes113

Wipe Bending In addition to V-bending, another common bending method is wipe bending, sometimes called edge bending. Wipe bending requires the sheet to be held against the wipe die by a pressure pad. The punch then presses against the edge of the sheet that extends beyond the die and pad. The sheet will bend against the radius of the edge of the wipe die. Sheet metal forming Design rules Bend location – A bend should be located where enough material is present, and preferably with straight edges, for the sheet to be secured without slipping. The width of this flange should be equal to at least 4 times the sheet thickness plus the bend radius. Bend radius Use a single bend radius for all bends to eliminate additional tooling or setups Inside bend radius should equal at least the sheet thickness Bend direction - Bending hard metals parallel to the rolling direction of the sheet may lead to fracture. Bending perpendicular to the rolling direction is recommended. Any features, such as holes or slots, located too close to a bend may be distorted. The distance of such features from the bend should be equal to at least 3 times the sheet thickness plus the bending radius. In the case of manual bending, if the design allows, a slot can be cut along the bend line to reduce the manual force required. Manufacturing and assembly technologies - Assembly and joining processes114

Sheet metal forming Roll forming Roll forming, sometimes spelled roll forming, is a metal forming process in which sheet metal is progressively shaped through a series of bending operations. The process is performed on a roll forming line in which the sheet metal stock is fed through a series of roll stations. Each station has a roller, referred to as a roller die, positioned on both sides of the sheet. The shape and size of the roller die may be unique to that station, or several identical roller dies may be used in different positions. The roller dies may be above and below the sheet, along the sides, at an angle, etc. As the sheet is forced through the roller dies in each roll station, it plastically deforms and bends. Each roll station performs one stage in the complete bending of the sheet to form the desired part. The roller dies are lubricated to reduce friction between the die and the sheet, thus reducing the tool wear. Also, lubricant can allow for a higher production rate, which will also depend on the material thickness, number of roll stations, and radius of each bend. The roll forming line can also include other sheet metal fabrication operations before or after the roll forming, such as punching or shearing. Roll Forming Line Manufacturing and assembly technologies - Assembly and joining processes115

Sheet metal forming The roll forming process can be used to form a sheet into a wide variety of cross-section profiles. An open profile is most common, but a closed tube-like shape can be created as well. Because the final form is achieved through a series of bends, the part does not require a uniform or symmetric cross-section along its length. Roll forming is used to create very long sheet metal parts with typical widths of 1-20 inches and thicknesses of 0.004-0.125 inches. However wider and thicker sheets can be formed, some up to 5 ft. wide and 0.25 inches thick. The roll forming process is capable of producing parts with tolerances as tight as ±0.005 inches. Typical roll formed parts include panels, tracks, shelving, etc. These parts are commonly used in industrial and commercial buildings for roofing, lighting, storage units, and HVAC applications. Roll Forming Line Manufacturing and assembly technologies - Assembly and joining processes116

Sheet metal forming Spinning Spinning, sometimes called spin forming, is a metal forming process used to form cylindrical parts by rotating a piece of sheet metal while forces are applied to one side. A sheet metal disc is rotated at high speeds while rollers press the sheet against a tool, called a mandrel, to form the shape of the desired part. Spun metal parts have a rotationally symmetric, hollow shape, such as a cylinder, cone, or hemisphere. Examples include cookware, hubcaps, satellite dishes, rocket nose cones, and musical instruments. Spinning is typically performed on a manual or CNC lathe and requires a blank, mandrel, and roller tool. The blank is the disc-shaped piece of sheet metal that is pre-cut from sheet stock and will be formed into the part. The mandrel is a solid form of the internal shape of the part, against which the blank will be pressed. For more complex parts, such as those with reentrant surfaces, multi-piece mandrels can be used. Because the mandrel does not experience much wear in this process, it can be made from wood or plastic. However, high volume production typically utilizes a metal mandrel. Manufacturing and assembly technologies - Assembly and joining processes117

There are two distinct spinning methods, referred to as conventional spinning and shear spinning. In conventional spinning, the roller tool pushes against the blank until it conforms to the contour of the mandrel. The resulting spun part will have a diameter smaller than the blank, but will maintain a constant thickness. Sheet metal forming The mandrel and blank are clamped together and secured between the headstock and tailstock of the lathe to be rotated at high speeds by the spindle. While the blank and mandrel rotate, force is applied to the sheet by a tool, causing the sheet to bend and form around the mandrel. The tool may make several passes to complete the shaping of the sheet. This tool is usually a roller wheel attached to a lever. Rollers are available in different diameters and thicknesses and are usually made from steel or brass. The rollers are inexpensive and experience little wear allowing for low volume production of parts. Manufacturing and assembly technologies - Assembly and joining processes118

Sheet metal forming In shear spinning, the roller not only bends the blank against the mandrel, it also applies a downward force while it moves, stretching the material over the mandrel. By doing so, the outer diameter of the spun part will remain equal to the original blank diameter, but the thickness of the part walls will be thinner. Conventional Spinning vs. Shear Spinning Manufacturing and assembly technologies - Assembly and joining processes119

Sheet metal forming Sheet metal stamping/drawing – car industry Examples-sheet metal formed Manufacturing and assembly technologies - Assembly and joining processes120

Sheet metal forming Stamping Auto body panels 3 to 5 dies each Prototype dies ~ $50,000 Production dies ~ $0.75-1 Forming dies Trimming station Flanging station Manufacturing and assembly technologies - Assembly and joining processes121

Sheet metal forming Objectives By the end of today you should be able to… … ….describe different forming processes, when they might be used, and compare their production rates, costs and environmental impacts.… calculate forming forces, predict part defects (tearing, wrinkling, dimensional inaccuracy), and propose solutions … explain current developments: opportunities and challenges Manufacturing and assembly technologies - Assembly and joining processes122

Introduction  Metal manufacturing is essential for all areas of the economy. Because of their strength, stiffness, and long-term durability, metal components are used in applications from appliances to construction parts and car body panels.  Traditional metal manufacturing techniques include forming, casting, molding, joining, and machining.  Sheet metal forming involves various processes where force is applied to a piece of sheet metal to plastically deform the material into the desired shape, modifying its geometry rather than removing any material.  Sheet metals can be bent or stretched into a variety of complex shapes, permitting the creation of complex structures with great strength and a minimum amount of material.  Sheet metal forming is the most cost-effective forming procedure today for manufacturing parts in large quantities. It can be highly automated in factories or, at the other end of the spectrum, manually operated in metal workshops for small series parts. It is a versatile, consistent, and high-quality procedure to create accurate metal parts with limited material waste. 123Manufacturing and assembly technologies - Assembly and joining processes Sheet metal forming

Manufacturing and assembly technologies - Assembly and joining processes124 START

Manufacturing and assembly technologies - Assembly and joining processes125 Sheet metal forming OVERVIEW OF METAL FORMING Metal forming processes can be classified into two basic categories: 1.bulk deformation processes 2.sheet metalworking processes Each category includes several major classes of shaping operations, as indicated in Figure

Manufacturing and assembly technologies - Assembly and joining processes126 Sheet metal forming OVERVIEW OF METAL FORMING b Figure illustrates the following basic operations in bulk deformation: Basic bulk deformation processes: (a) rolling, (b) forging, (c) extrusion, and (d) drawing. Relative motion in the operations is indicated by v; forces are indicated by F. The term bulk describes the workparts that have this low area-to-volume ratio. Starting work shapes for these processes include cylindrical billets and rectangular bars. Bulk Deformation Processes Bulk deformation processes are generally characterized by significant deformations and massive shape changes, and the surface area-to-volume of the work is relatively small.

Manufacturing and assembly technologies - Assembly and joining processes127 Sheet metal forming Basic bulk deformation processes:  Rolling. This is a compressive deformation process in which the thickness of a slab or plate is reduced by two opposing cylindrical tools called rolls. The rolls rotate so as to draw the work into the gap between them and squeeze it.  Forging. In forging, a workpiece is compressed between two opposing dies, so that the die shapes are imparted to the work. Forging is traditionally a hot working process, but many types of forging are performed cold.  Extrusion. This is a compression process in which the work metal is forced to flow through a die opening, thereby taking the shape of the opening as its own cross section.  Drawing. In this forming process, the diameter of a round wire or bar is reduced by pulling it through a die opening.

Manufacturing and assembly technologies - Assembly and joining processes128 Sheet metal forming FUNDAMENTALS OF METAL FORMING - Review Questions 1) What are the differences between bulk deformation processes and sheet metal processes? Answer. In bulk deformation, the shape changes are significant, and the workparts have a low area-to-volume ratio. In sheet metal processes, the area- to-volume ratio is high. 2) Why is the term pressworking often used for sheet metal processes? Answer. The term pressworking is used because most sheet metal operations are performed on presses. 3) What is the difference between deep drawing and bar drawing? Answer. Deep drawing is a sheet metal forming process used to fabricate cup- shaped parts; bar drawing is a bulk deformation process used to reduce the diameter of a cylindrical workpart.

Manufacturing and assembly technologies - Assembly and joining processes129 Sheet Metalworking Sheet metal forming  Sheet metalworking includes cutting and forming operations performed on relatively thin sheets of metal.  Typical sheet-metal thicknesses are between 0.4 mm (1/64 in) and 6 mm(1/4 in).  When thickness exceeds about 6 mm, the stock is usually referred to as plate rather than sheet.  The sheet or plate stock used in sheet metalworking is produced by flat rolling.  The most commonly used sheet metal is low carbon steel (0.06%–0.15% C typical).  Its low cost and good formability, combined with sufficient strength for most product applications, make it ideal as a starting material. Metal Forming is a large set of manufacturing process by which a raw material converted into a product. In this process, we apply stresses like tension, compression, shear, etc. to deformed the raw material.

Manufacturing and assembly technologies - Assembly and joining processes130 Sheet Metalworking Sheet metal forming  Sheet-metal parts are generally characterized by high strength, good dimensional accuracy, good surface finish, and relatively low cost.  For components that must be made in large quantities, economical mass- production operations can be designed to process the parts.  Aluminum beverage cans are a prime example.  Sheet-metal processing is usually performed at room temperature (cold working). The exceptions are when the stock is thick, the metal is brittle, or the deformation is significant. These are usually cases of warm working rather than hot working. Most sheet-metal operations are performed on machine tools called presses. The term stamping press is used to distinguish these presses from forging and extrusion presses. The tooling that performs sheet metalwork is called a punch-and-die; the term stamping die is also used. The sheet-metal products are called stampings. To facilitate mass production, the sheet metal is often presented to the press as long strips or coils.

Manufacturing and assembly technologies - Assembly and joining processes131 Sheet Metalworking Sheet metal forming Most sheet-metal operations are performed on machine tools called presses. The term stamping press is used to distinguish these presses from forging and extrusion presses. The tooling that performs sheet metalwork is called a punch-and-die; the term stamping die is also used. The sheet-metal products are called stampings. To facilitate mass production, the sheet metal is often presented to the press as long strips or coils. Final sections of the chapter cover various operations that do not utilize conventional punch-and-die tooling, and most of them are not performed on stamping presses. The three major categories of sheet-metal processes are (1)cutting, (2), bending, and (3) drawing. Cutting is used to separate large sheets into smaller pieces, to cut out part perimeters, and to make holes in parts. Bending and drawing are used to form sheet-metal parts into their required shapes.

Manufacturing and assembly technologies - Assembly and joining processes132 The basic sheet metal operations are sketched in Figure and are defined as follows: Bending. Bending involves straining of a metal sheet or plate to take an angle along a (usually) straight axis. Drawing. In sheet metalworking, drawing refers to the forming of a flat metal sheet into a hollow or concave shape, such as a cup, by stretching the metal. A blankholder is used to hold down the blank while the punch pushes into the sheet metal, as shown in Figure. To distinguish this operation from bar and wire drawing, the terms cup drawing or deep drawing are often used. Shearing. This process seems somewhat out-of-place in a list of deformation processes, because it involves cutting rather than forming. A shearing operation cuts the work using a punch and die, as in Figure. Sheet metal forming

Manufacturing and assembly technologies - Assembly and joining processes134 Sheet metal forming

Manufacturing and assembly technologies - Assembly and joining processes135 Sheet metal forming  Curling sheet metal is the process of adding a hollow, circular roll to the edge of the sheet.  The curled edge provides strength to the edge and makes it safe for handling.  Curling is different than a tear drop hem because in a curl the edge finishes inside itself, where a hem leaves the initial edge exposed.  Sheet Metal Hems are formed using very different methods, though produces features with similar uses and functionality.  Curls are most often used to remove a sharp untreated edge and make it safe for handling. Types of sheet metal forming processes - #1) Curling

Manufacturing and assembly technologies - Assembly and joining processes136 Sheet metal forming Curls come in two basic forms, off center and on center rolls. A.Off center rolls have the center of the roll above the original plane of the sheet metal. B.On center rolls will have the center of the roll in line with the plane of the sheet metal. The type of curl you produced is a matter of design intent and the machinery available. As we will discuss below the process of forming a curl is different for each type of fabrication machine. Because of this certain machines will lend themselves towards one style or another Types of sheet metal forming processes - #1) Curling

Manufacturing and assembly technologies - Assembly and joining processes137 Sheet metal forming Forming a Sheet Metal Curl How a curl is formed depends entirely on the type of machinery you wish to use. Curls can be fabricated through roll forming, stamping, leaf bending, and on a traditional press brake. Each machine will have its own set of tooling for achieving the curl. Here we will be discussing the fabrication and tooling methods for forming on a leaf bender and press brake. Types of sheet metal forming processes - #1) Curling

Manufacturing and assembly technologies - Assembly and joining processes138 Sheet metal forming Forming a Sheet Metal Curl a)Forming a Curl on a Panel Bender  Curling on a panel or leaf bender is often limited to off center curls because most panel benders do not have tooling profiles which can create the necessary down bend to put the curl on center. Off center rolls however are very easily formed on this type of machine.  The desired radius is created by Step Bonding a progressively larger radius into the sheet, beginning with the desired curl radius minus the material thickness, and ending with the desired curl radius.  The smaller radius is formed first to allow the material to finish inside itself. The process of step bending involves producing very small bends in very close to each other, and while the finished bend is technically a polygon, it’s often impossible to detect the steps if they are formed correctly. For lighter gauges a hand operated panel bender can be the most affordable method for creating a curl. Types of sheet metal forming processes - #1) Curling

Because of this the tooling is typically unbalanced, meaning the tonnage isn’t evenly distributed front to back, so stabilizing features are sometimes incorporated. When a stabilizing bar is used it allows for the two stages to be combined into one set of tooling. Below is an example of a one setup, three stage tooling. Manufacturing and assembly technologies - Assembly and joining processes b) Forming a Curl on a Brake Press To curl sheet metal on a Brake Press specialized tooling is required. Most curls are formed in three stages and some setups require two tooling setups with specialized tooling for each stage. The first 2 stages form the curves required to form the curl, and the third stage closes the curl. A locating notch is typical for this type of tooling to ensure that the first and second stages are bent in the correct location. Below is a typical two setup, three stage tooling. Sheet metal forming 11 Types of sheet metal forming processes - #1) Curling

Manufacturing and assembly technologies - Assembly and joining processes140 Sheet metal forming Examples Two examples of curling are shown in Fig.1 and Fig. 2. Curling gives stiffness to the workpiece by increasing the moment of inertia at the ends, and providing smooth rounded edges Fig.1 Curling process 1 st example: the edge of the sheet metal is bent into the cavity of a punch Types of sheet metal forming processes - #1) Curling

Manufacturing and assembly technologies - Assembly and joining processes141 Sheet metal forming 2 nd example: the circular edge of the initial deep-drawn workpiece is curled by a tool that incorporates a cavity punch. Fig.2 Circular edge curling Types of sheet metal forming processes - #1) Curling

Manufacturing and assembly technologies - Assembly and joining processes142 Sheet metal forming The curling force is given by the equation: SOLUTIONSOLUTION Types of sheet metal forming processes - #1) Curling

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Manufacturing and assembly technologies - Assembly and joining processes1

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