IEC COLLEGE OF ENGINEERING AND TECHNOLOGY PROJECT REPORT ON LEAD SCREW OPERATED SCISSOR LIFT UNDER THE GUIDANCE OF: SUBMITTED BY: MR. ANUJ GUPTA SHIVANI PANDEY SHABA NAAZ VIKAS GOVIND RAO VIMAL KUMAR UDAY KUMAR ROHIT YADAV

INTRODUCTION

What is scissor lift? A scissor lift is a type of platform which can usually only move vertically. The mechanism to achieve this is the use of linked, folding supports in cris cross ‘X’ pattern. The upward motion of the lift can be achieve by the application of pressure to the out side of the lowest set of supports, elongating the crossing pattern, and propelling the work plat form vertically . The plat form may also have an extending ‘bridge’ to allow closer access to the work area.

Pantograph mechanism of scissor lift A pantograph is a mechanical linkage connected in a special manner based on parallelograms so that the movement of one pen, in tracing an image, produces identical movements in a second pen. If a line drawing is traced by the first point, an identical, enlarged or miniaturized copy will be drawn by a pen fixed to the other. Because of their effectiveness at translating motion in a controlled fashion, pantographs have come to be used as a type of motion guide for objects large and small. A common example of the use of a pantograph assembly as mechanical guide frame is the extension arm of an adjustable wall-

In this figure point O is fixed. Point Q and point P is movable. Link LP follow the same path trace by link QN. As point Q moves up and down point P will also follow the same path and it will also move up and down. Hence Scissor lift is based on pantograph.

Lead screw OPERATED SCISSOR LIFT

What is lead screw operated scissor lift? A lead operated scissor lift is same as the normal scissor lift except that it has lead screw that is attached with the scissor arms that are connected with the low power motors at its base. These screw help in the up and down movement of the arms of the lift.

LIFT AT INITIAL POINT 21CM FROM GROUND

LIFT AT EXTEND AT 45 CM FROM GROUND

Why we are using lead screw? As our project is the prototype of the models that are used in the industries so instead of actuators we are using the lead screw. With the help of lead screw and its movement the arms of the lift moves up and down. A lead screw is such a part which when rotates gives the linear motion. Lead screw is the devices which can transmit the linear motion by the action of rotary motion. The speed of the screw depends upon the motor connected to it.

The similar concept we are using in this scissor lift We are using lead screw because it is economical. Instead of actuators we are using lead screw to lift the arms of the scissor lift. It is easily available.

Materials used Following are the list of materials that are use in making the lift: Links ( mild steel) Lead screw Aluminium sheet Nut , bolts (10 mm) Iron rods.

Description of project

Our project is completely based on the mechanism of the pantograph and working of the lead screw. As the screw is attached to the base and the power is supplied with the help of motor. Among the four lower links the two links are fixed and two are movable. As the screw moves forward by moving linearly the links that are movable moves left.

This results in the opening of the lift as the the links attached to the movable as well as fixed links moves upward. Similarly as the screw backward the movable links moves in the right direction and thus resulting in the closing of the lift.

TYPES OF SCREWS Power screws are classified by the geometry of their thread. V-threads are less suitable for leadscrews than others such as Acme because they have more friction between the threads. Their threads are designed to induce this friction to keep the fastener from loosening. Leadscrews, on the other hand, are designed to minimize friction. Therefore, in most commercial and industrial use, V-threads are avoided for leadscrew use. Nevertheless, V-threads are sometimes successfully used as leadscrews, for example on micro lathes and micromills

SQUARE THREAD Square threads are named after their square geometry. They are the most efficient, having the least friction, so they are often used for screws that carry high power. But they are also the most difficult to machine, and are thus the most expensive

ADVANTAGES OF LEAD SCREW Large load carrying capability Compact Simple to design Easy to manufacture; no specialized machinery is required Large mechanical advantage Precise and accurate linear motion Smooth, quiet, and low maintenance Minimal number of parts Most are self-locking

DESCRIPTION OF PARTS

PARTS OF GEAR OPERATED SCISSOR LIFTS The platform: Upper table lower table Scissor leg

2. Lead screw 3. Wheels 4. Arms (links) 5 2.Lead screw 3. Wheels 4. Arms (links) 5. Wooden board (for base platform) 6. Washer (to restrict the motion)

DESIGNING AND CALCULATION Dimension Links length = 27 cm Links thickness = 0.5 cm Links breadth = 2.4 cm Lead screw pitch = 0.2cm Lead screw internal diameter = 1 cm Lead screw outer diameter = 1.2 cm Nut & Bolt = 1 cm (both) Distance between two legs = 14 cm Base platform = 40x30x1.7 cm Slots length = 14 cm Slots height = 1.3 cm

Advantages of scissor lift 1) Scissor lifts can help operators to reach areas that might otherwise be inaccessible. Larger models can extend to a height of 18.8 meters (62 feet) 2) Scissor lifts are so simple to operate and move that they reduce fatigue in operators, increasing levels of production. 3) Scissor lifts eliminates Repetitive strain injury (RSI) by avoiding the need to bend and stretch repeatedly.

4) Turn tables can be added to scissor lift to allow the operator to rotate loads. This saves time and minimises the risk of injury from heavy loads. 5) Tilters can be used on scissor lift to allow the operator to position a product by tilting the platform, sliding goods off. Operators do not have to risk injury by lifting heavy load. 6) When not in use and fully retracted scissor lifts take up a little space in a warehouse or office.

Uses of a scissor lift Scissor lifts are generally the material handling devices which are used in material handling department of any company or firm. These lifts can be used in performing various tasks which can not be performed easily. Ex sealing works etc

CONCLUSION Finally we make a conlusion that we have constructed lead screw scissor lift that is capable of lifting load about a height of 24 cm. Initial height 21 cm. Final height 45 cm.

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