Shaper Machine

Shaper: is a reciprocating type of machine tool intended primarily to produce flat surface. It is used for cutting the light weight metal or any object. These surfaces may be horizontal, vertical, or inclined. The metal working shaper was developed in year 1836 by James Nasmyth an, English man. Modern shapers can generate contoured surface. It is reciprocal machine. It is cut on forward direction.

Type of shaper machine:

1) According to the type of mechanism used for giving reciprocating motion to the ram:

1. Crank type shaper machine: This is the most common type of shaper in which a single point cutting tool is given a reciprocating motion equal to the length of the stroke desired while the work is position on an adjustable table. This is most common type of shaper in which a single point tool is given a reciprocating motion equal to the length of stoke desired while the work is clamped in the position on an adjustable table. In construction, the crank shaper employs a crank mechanism to change circular motion of a large gear called “bull gear” incorporated in the machine to reciprocating motion of the ram. The bull gear receives power either from an individual motor or from an overhead line shaft if it is a belt driven shaper.

2. Geared type shaper machine: The reciprocating motion of the ram in some type of shaper is affected by means of a rack and pinion. In this machine, the speed and the direction in which the machine will traverse depends on the number of gear in the gear train. This type of shaper in not very widely used. The rack teeth which are cut directly below the ram mesh with a spur gear. The pinion meshing with the rack is driven by a gear train.

3. Hydraulic type shaper machine: In a hydraulic shaper, reciprocating movement of the ram is obtained by hydraulic power. In this machine, the cutting speed and force of the ram drive are constant from the very beginning to the end of the cut. It has also; the machine does not make any noise and operates very quietly. Oil under high pressure is pumped into the operating cylinder fitted with a piston. The end of the piston rod is connected to ram. The high pressure oil first act on one side of the piston and then on the other causing the piston to reciprocate and the motion is transmitted to the ram. 

Hydraulic type shapers are three types: Horizontal, Vertical, or travelling head type.

2) According to the position and travel of ram:

1. Vertical type shaper machine: In a vertical shaper, the ram holding the tool reciprocates in a vertical axis. It may be crank driven, rack driven, screw driver or hydraulic power driven. The work table is a given cross, longitudinal and rotary movement.

2. Horizontal type shaper machine: In a horizontal shaper, the ram holding the tool reciprocates in a horizontal axis. Horizontal shapers are mainly used to produce flat surface.

3. Travelling head type shaper machine: In a traveling head shaper, the ram carrying the tool while it reciprocates moves crosswise to give the required feed. Heavy work is doing this machine.

3) According to the type of design of the table:

1. Standard or plain type shaper machine: A shaper is termed as standard or plain when the table has only two movements, vertical and horizontal, to give the feed. The table may or may not be supported at the end.

2. Universal type shaper machine: In a machine, the addition to the two movement provide on the table of a standard shaper, the table can be swiveled about  an axis parallel to the ram ways, and the upper portion of the table can be tilted about a second horizontal axis perpendicular to the first axis.

4) According to the type of cutting stroke:

1. Push type shaper machine: This is the most general type of shaper used in common practice. The metal is removed when the ram moves away from the column, i.e. pushes the works.

2. Draw type shaper machine: In a draw shaper, the metal is removed when the ram moves towards the column of the machine i.e. draws the work towards the machine. In this machine vibration in is practically eliminated.

Parts of shaper: Base, Column, Crossrail, Saddle, Table, Ram, Toolhead, Tool clapper box, Apron clamping bolt, Down hand feed wheel, Feed disc, Elevating screw, Pawl mechanism.

Shaper size: The size of a shaper is determined by the maximum length of stock or cut it can make. The usual size ranges from 175 to 900 mm. The length of stroke indicates, in addition to the general size of the machine, the size of a cube that can be hold and planed in the shaper. Thus in a 250 mm shaper the length of stroke may be adjusted from 0to 250 mm, the cross feed adjustment of the table will be 250 mm and the extreme bottom position of the table to accommodate a workpiece 250 mm high. 

Principle parts of shaper machine: Following are the shaper machine parts:

Base: The base is also known as ‘bed’. It is a necessary support required for all machine tools the base may be rigidly bolted to the floor in the workshop or no the bench according to the size of the machine. It is made so that it can interred total.

Column: It is a box type cast iron body. The column is the box type( housing) casting mounted upon the base. It include the ram drive mechanism and ram is reciprocating on the top of the column.

Cross rail: The cross-rail is mounted on the front vertical guide- ways of the column it is the adjusting the table and the cross movement of the table.

Saddle: It is the mounted upon the cross rail which the hold the table on its top place.

Table: It is mounted on in the form of the column and downward of clapper box.

Ram: It is a reciprocating parts of shaper machine. It is used for cutting the metal and moved the backward and forward direction for cutting.

Tool head: It is the device in which is held the tool. it can slide up and down and can be swing to a desired angle to set the tool at a desired position for the operation.

Elevating screw: It is used for give (adjusted) the height of the table.

Bull gear: Bull gear is situated in the column which is rotated free on its place.

Work holding device: The top and side of the table of a shaper have T-slot for the clamping the work. The work may be supported on the table by the following methods depending on the nature of the workpiece:

1. Clamp in a vice: A vice is a quick method of holding and locating relatively small and regular shaped work pieces. It is fitted on the table. A machine vice is classified into following types:

Plain vice - single screw and double screw.

Swivel vice, Table, Step- block, Universal vice.

2. Clamping work on table: T-bolts and clamp, Stop pines, Stop pines and toe doges, Strip and stop pines.

3. Angle plate: It is holding for “L” shaped work piece, angle plates are used. Angle plates are made of cast iron and are placed on two sides of exactly 90 degree. One of the sides is clamped to the table by t-bolts while the other side’s hole the work by clamps.

4. V-block: It is used for holding round rods V-blocks at supported on two v- block at its two ends and is clamped to the table by t-bolt and clamps. The tool may be made to reciprocate between the two clamps for cutting grooves or key ways. It is made of cast iron or steel and is accurately machined.

5. Shaper index centres: This is special attachment used for cutting equally spaced grooves or splines on the periphery of a round work. In special cause, it may be used for cutting gears. A shaper center consists of a head stock and a tailstock and the work is mounted b/w two centres. Mounted upon the headstock spindle is the worm gear (4) which meshes with the worm. The handle (2) is connected with the worm shaft. Rotation of the handle (2) causes the worm gear (4) to rotate and the motion is transmitted to the work through a catch plate and carrier. After cutting a clot or groove on the top of the work, it may be turned to a predetermined amount by an index plate (3) and index pin (1). The index plate is mounted on the worm gear shaft. The index plate has a series of holes around its circumference and is locked in many desired position by engaging the index pin in the corresponding hole. Index plates are provided with various numbers of holes.

Shaper mechanism: In a shaper, rotating movement drivers is converted into reciprocating types of movement by the mechanism by contains within the column of the machine. The RAM helping the reciprocating movement in the standard shaper metal is removed in the forward cutting stroke while the returned stroke those ideal no metal is removed in during this period. This mechanism is known a “QUICK RETURENED MACHANISM”. To reduce the total machining time it is necessary to reduce the time taken by the return stock. Thus the shaper mechanism should be so designed that it can allow the ram holding the tool to move at a comparatively slower speed during the forward cutting stock, the cutting speed depending upon the type of material and machining condition, whereas during the stock it can allow the ram to move at a faster rate to reduce the idle return time. This mechanism is known as quick return mechanism.

Shaper machine sizes: The size of a shaper is determined by the maximum length of stroke or cut it can make. the usual size ranges from 175 to 900 mm.

Following are also shaper mechanism:

1. Crank and slotted link mechanism.

2. Whitworth quick return mechanism.

3. Hydraulic shaper mechanism.

1. Crank and slotted link mechanism: The crank and slotted lank mechanism is motion or power its transmitted to the bull gear through a pinion which received it motion from indivisval motor speed of a bull gear may be changed by different combination of gearing bull gear is a largest gear, mountain with in a column bolted to the center of the bull gear is a reader slide which carries a sliding block into which a crank pins each fitted.

Quick return mechanism: The principal of quick return mechanism when the links is in the position in ‘P M’ than RAM will be extreme back position of its stroke and when it is at ‘PN’ than stream forward position of RAM will ram have reached P M’ and ‘P N’ are shown tangent to creak pin circle the forward cutting stork there for take place when the crank rotted through the c1 -k- c2 are the returned stroke take place c2 – l - c1. The angular velocity of the crank pin be constant the returned stroke be there for completed with the shorted time for t is known as “quick return mechanism”. The ratio between the cutting and return time may be determined as formula:

                       [= cutting time/ returned time.]

Feed mechanism: In a shaper both down feed and crossfeed movement may be obtained. Unlike a lathe, these feed movements are provided intermittently and during the end return stock only. Vertical or bevel surface are produced by rotating the downfeed screw of the Toolhead by hand. Crossfeed movement is used to machine a flat horizontal surface. This is down by rotating the crossfeed screw either by the hand of power. Rotation of the cross feed screw causes the table mounted upon the saddle to move sideways through a predetermined amount at the end of each return stock so as to bring the uncut surface of the work in the direct path of the reciprocating tool. 

Angular setting: In order to try the machined accuracy of shaped angular work the job must often be removed from the machine and should any correction be necessary, the task of setting it up again to its original positions may occupy hours of work. Thus may be avoided by a careful preliminary setting with vernier protractor or sine bar.

Shaper operation: A shaper is a versatile machine tool primarily designed to generate a flat surface by a single point cutting tool. But it may also be used to perform many other operations. The different operations which a shaper can perform are as follows:

1. Machining horizontal surface: The work is held directly on the table or in a vise. The table is adjusted vertically according to the height of the work pieces. The length and position of stroke are adjusted. The stroke length will be 20 mm longer than the work. The stroke position is adjustened so that the tool will have an approach of about 15 mm and over travel of about 5 mm. depth of cut is given by the down feed screw of the tool head. A shaper is mostly used to machine a flat, true surface on a workpiece held in a vice or other holding devices. After the work is properly held on the table, a planning tool is set in the tool post with minimum overhang. The table is raised till there is a clearance of 25 to 30mm between the tool and the workpiece. The length and position of stroke are then adjusted. The length of stroke should be nearly 20 mm longer then the work and the position of stroke is so adjusted that the tool begins to move from a distance of 12 to 15 mm before the beginning of the cut and continues to move 5 to 8 mm after the end of the cut.

2. Machining vertical surface: A vertical cut is made while machining the end of a workpiece, squaring up a block or cutting a shoulder. Vertical machining is done to cut the vertical side of the work pieces. Work is held in a vice or directly on the table. The vertical surface of the work pieces is set parallel with the ram movement; a side cutting tool is set in the tool post. Storage length and positions are adjusted. The vertical slide of the tool head is set at zero position of the swivel base. The apron is tilted in a direction away from the surface being cut. This prevents the tool from rubbing on the work surface during return stroke. The down feed is given by rotating the down feed screw in the tool head.

3. Machining angular surface: The work is held in a vise or directly on the table. The vertical surface of the work pieces is set parallel with the ram movement. The vertical slide of the tool head is swiveled to the required angle. The apron is tilted in a direction away from the surface being cut. Angular down feed of the tool is obtained by rotating the down feed screw handle. Angular machining is done for making vee blocks and dovetails. Angular surface can also be machined in a universal shaper. Angular surfaces can also be machined by using a universal vise.

4. Machining slots, grooves and keyways: For cutting slots or key ways a square adapted tool (like a parting tool) is used. The ends of the key way are first drilled to the required depth on a drilling machine. The work piece is held on the vise .the length and positions of the stroke are adjusted accurately. The cutting is done at a slow speed.

5. Machining irregular surface: Any irregular surface can be cut in a shaper. A round nose tool is used. Both the cross feed and vertical feed are given at the same time. The cross feed is given through the table. Vertical feed is given by the tool head. The apron is tilted suitably to avoid rubbing of the tool during stroke.