Dr. Subhash Technical Campus ACTIVE LEARNING PROCESS SHAPER MACHINES Prepared by: Jani Kishankumar Pareshbhai (130830119047) Subject :- MP-1 Guided by :- Prof. V M Patel Dr. Subhash Technical Campus

SHAPER Shaper is a reciprocating type of machine tool used for producing flat surfaces in which the ram moves the cutting tool backwards and forwards in a straight line. Generally Shaper machine can produce any surfaces composed of straight line elements.

Shaper Machine

Surfaces Produced by Shaper Machine

Working Principle of Shaper Machine A Single Point cutting tool is held in the tool holder, which is mounted on the ram. The workpeice is rigidly held in a vice or clamped directly on the table. The table may be supported at the outer end. The arm reciprocates and thus cutting tool held in the tool holder moves forward and backward over the workpeice. In standard shaper, cutting of material takes place during the forward stroke of the ram. The backward stroke of the ram remains idle and no cutting takes place during this stroke. The time taken during the idle stroke is less compared to forward stroke and this is obtained by quick return mechanism.

Working Principle of Shaper Machine

Cutting Parameters for Shaper Machine

Classification Of Shaper Machines :- Shaper Machines are classified under the following headings : According to the type of mechanism used for giving reciprocating motion of the ram. (i) Crank Type, (ii) Geared Type, (iii) Hydraulic Type 2. According to the type of design of the table. (i) Standard Shaper, (ii) Universal Shaper 3. According to the position and travel of ram. (i) Horizontal Type, (ii) Vertical Type, (iii) Travelling Head Type 4. According to the type of cutting stroke. (i) Push Type, (ii) Draw Type

Principle Parts Of Shaper Machine

Shaper Tool Head

Shaper Drive Mechanism Slotted Lever Type

Shaper Drive Mechanism Whitworth Quick Return Mechanism

Shaper Drive Mechanism Hydraulic Drive For Shaper

Advantages Of Hydraulic Drive Stepless speed variation is obtained over a wide range which can be adjusted without difficulty even under load. The control of rate of flow and pressure is quite easy. The drive has a built in protection from overload. The number of moving parts is less as such the system operates quickly with high efficiency. The dynamic properties and high speed response of a hydraulic drive are much better because of the lower weight to power ratio of hydraulic units. The drive has a self lubricating property. It is convenient for automation. The drive is smooth and jerk free resulting in good surface finish produced. The power consumption is low since there are less number of moving parts. The assembly of unit is easier since it is not necessary to achieve very close alignment.

Disadvantages Of Hydraulic Drive The initial cost of hydraulic unit is more than that of the mechanical units. The compressibility of oil however is small and the elasticity of oil of carrying elements impart a lack of rigidity to the hydraulic drive. A positive motion such as required for screw cutting is very difficult to attain due to leakage or slip and the slight compressibility. Any change in the properties of the oil due to temp. variation may lead to slight variation in drive. Air pockets formed in the hydraulic lines result in irregular, jerky motion of the ram or table. Leakage of oil poses major problem in machine tool. When amount of leakage increases the capacity of the unit reduces and the efficiency goes down.

Automatic feed Mechanism Shaper Feed Mechanism Automatic feed Mechanism

SHAPER TOOLS Shaper tools are single point similar to lathe tools and are frequently held in the same way. Difference between Shaper tool and Lathe Tool. A Lathe Tools is subjected to a uniform, practically constant cutting pressure whereas A Shaper tool has to withstand repeated shocks caused by the cutting strokes. A Shaper Tool generally have larger nose radius compared to lathe tools to withstand shock loads. A Shaper tool is more rigid and heavier than Lathe tool. A Lathe tool has sufficient side clearance angles as it is to be continuously fed. In Shaper feed is given at the end of the stroke hence a smaller clearance angle in the order of 2 – 3 degree is enough.

SHAPER TOOLS Shaper tools are classified in to following varieties. Rough and Finishing Tool Straight and Cranked neck Tool Left-hand and Right-hand Tool Round nose, Straight nose and Flat nose Tool Slot cutting, Parting off and side recessing Tool

SETTING SHAPER FOR SHAPING OPERATION

SETTING SHAPER FOR SHAPING OPERATION

SETTING SHAPER FOR SHAPING OPERATION The setting of Shaper preparatory to a shaping operation involves Setting of the length of stroke. Number of Ram cycles Position of the Tool Feed rate Position of tool head and Clapper box

SETTING SHAPER FOR SHAPING OPERATION In mechanical crank shapers the length of the stroke set is usually about 25 mm more than the length of job because the tool starts from rest at the beginning of stroke and picks up slowly to the maximum velocity at the middle of the stroke and then back to zero velocity at the end of the stroke. The extra 25 mm is arranged in such away that the tool approaches the job over about 20 mm and runs over the job about 5 mm. This approach and overtravel permits the tool to have an appreciable speed at the beginning and the end of the cut.

CALCULATIONS The cutting speed on horizontal shaper is the average of the tool during the cutting stroke and it depends on The number of ram strokes per minute The length of stroke Cutting to return time ratio Suggested Cutting Speed (V) = Distance / Time (V) = ( N * L ) / [ 60000 * { r / ( 1 + r ) } ] m/s. Where, L = length of stroke to be set for the job, mm = length of the job + overtravel N = Number of ram cycles per minute V = Suggested cutting speed (m/s) r = Cutting to Return time ratio Where, ( N*L / 60 ) is the distance covered in one second and ( r / ( 1 + r ) ) is fraction of each second spent in cutting.

CALCULATIONS Ratio ( r / ( 1 + r ) ) is a machine constant and usually designated as C. It may be defined as the ratio of the cutting time to total cycle time for the machine. Number of strokes required to cover the width = ( b / f ) Where, b = Width of the job in mm to be fed across the line motion of the tool. f = feed rate in mm/stroke. Time taken for one cut across the surface = ( b / f * N ) = [ b * L / 60000 * V * C * f ] min.

Example No. : 01 Estimate the time required to machine a cast iron surface 275 mm long and 100 mm wide in one cut using a cutting speed 0.33 m/s and a feed rate of 0.25 mm/stroke on a shaper machine with cutting to return time ratio of 3/2. The available ram stroke on the machine are 28, 40, 60 and 90 strokes per minute. Solution : Stroke length (L) = 275 + 25 = 300 mm C = ( r / ( 1 + r ) ) = [ ( 3/2 ) / { 1 + ( 3/2 ) } ] = 3/5 N = ( 60000 * V * C / L ) = ( 60000 * 0.33 * 3 ) / ( 300 * 5 ) = 39.6 strokes/min. Select 40 strokes/min which is the nearest available number of stroke. Number of strokes needed = ( b / f ) = ( 100 / 0.25 ) = 400 strokes Time required for cut = ( b / f * N ) = 100 / ( 0.25 * 40 ) = 10 min.

Example No. : 02 Estimate the time required to for taking a complete cut on a plate 250 mm x 500 mm if the cutting speed is 10 m/min, the ratio of return to cutting time is 2 : 3 and feed is 2 mm. The clearance at each end is 50 mm. Solution : Stroke length (L) = 50 + 500 + 50 = 600 mm C = ( r / ( 1 + r ) ) = [ ( 3/2 ) / { 1 + ( 3/2 ) } ] = 3/5 N = ( 60000 * V * C / L ) = ( 60000 * 0.167 * 3 ) / ( 600 * 5 ) = 10 strokes/min. Number of strokes needed = ( b / f ) = ( 250 / 2 ) = 125 strokes Time required for cut = ( b / f * N ) = 250 / ( 2 * 10 ) = 12.5 min.