Shaper Machine

Shaper Machine

Shaper is a versatile machine which is primarily intended for producing flat surfaces. These surfaces may be horizontal, vertical or inclined. This machine involves the use of single point cutting tool held in a properly designed tool box mounted on a reciprocating ram.

WORKING PRINCIPLE

In shaper the job is rigidly held in machine vice. Tool is held in the tool post mounted on ram. This ram reciprocates to and fro and so the cutting of the material takes place in the forward stroke of ram and return stroke is ideal. The job is given index feed normal to the line of action of cutting tool. Principle parts of the shaper are:

COLUMN: 

It is a hollow structure consisting of two vertical walls and cast from cast iron. It is a rigid structure, gives support to the ram and is supported by the base. The cross rail carries table and table is derived in front of column. In one of two vertical walls, a hole is made to inspect the driving mechanism of the ram located in it.

BASE: 

It supports the whole machine and is bolted to the floor with the help of foundation bolts.

CROSS-RAIL: 

It is a box like structure over which the saddle slides horizontally. The cross rail is maintained accurately to the column. The table cross feed screw and the cross rail vertical feed are housed inside it.

SADDLE AND TABLE: 

The table is bolted on the saddle and the table is capable of moving in horizontal and vertical direction. It can be fitted in inclined position also. The job is supported on the table with the help of vice or some simple fixture. The table is provided with T-slots for clamping vice, fixture is and other tooling in it. Shaper ribs are provided: 
a. To adjust the saddle on the cross rail.
b. To adjust the ram on the column.
c. To adjust the tool slide on the swivel head plate.

SHAPER HEAD: 

It is fastened firmly to the front of the ram and consists of tool slide, tool post and clapper box. The head can be swiveled at any angle, tool is vertically fed by the vertical tool feed screw. The tool holder is fitted in the clapper which is fitted on the clapper box. Clapper block is free to pivot forward. The tool swings up on the return stroke otherwise work surface is likely to badly gauged and the tool quickly damaged by wear. Vertical feed is measured by micrometer dial near the handle.

RAM: 

Ram is a reciprocating member and it carries shaper head in the front, on which the cutting tool is mounted. It slides in the guide ways made on the top of the column. It should be designed as rigid as possible. A mechanism is provided inside the ram to change its position relative to the job.

POWER TRANSMISSION: 

The power to the shaper is transmitted from an electric motor through V-belt drive. The gears may be shifted by the speed change levers, large gear is the shaper is called bull gear or crank gear.

SPECIFICATION OF THE SHAPER

Shaper is specified by following parameters:
a. Maximum length of stroke
b. Table top (length*width) 
c. Table horizontal travel
d. Table vertical travel
e. Tool box-vertical travel
f. Number and range of speed obtained
g. Number and range of feeds
h. Swivel base, vise, width and depth of jaw
i. Swivel base
j. Size of tool
k. Speed of motor

FEED MECHANISM

Down feed and cross feed movements can be given at the end of the return stroke only by the automatic feed mechanism. The bull gear rotates driving disc. As the disc rotated through half of the revolution, the top of the rocking arm now moves in anti-clockwise direction only and the straight side of the pawl engages with the teeth of the ratchet wheel to move in anticlockwise direction only. As the driving disc is connected to the bull gear the table feed movement is affected when the bull gear or the driving disc rotates through half of the revolution. Rotating through other half imparts no feed movement. To reverse the direction of rotation and feed a knob at the top of the pawl is rotated through 1800 after removing the pin. The amount of feed may be altered by increasing the eccentrically at the driving disc.

SHAPER OPERATIONS

Horizontal flat surface machining: 

This is achieved by moving table under the tool. Automatic feed can be given or manual table is moved at the end of the return stroke. Length of the stroke should be 20mm longer than the job. Depth should be 1.5-3.0mm.

Vertical surface machining: 

Vertical feed is given to the tool by rotating the down feed screw by hand. It should be 0.25mm at the end of the return stroke.

Machining angular surface: 

The vertical slide of the tool head is swivelled to the required angle in either direction. The down feed is given by rotating the down feed screw.

Cutting slots and keyways: 

For cutting slots or keyways a square nose tool similar to a parting tool is selected. External keyways are cut on a shaft by firs drilling a hole at the blind end of keyways.

Irregular surface: 

Shaper can produce a convex or concave surface or a combination of the above surface by a forming tool. If the curve is sufficiently large, power cross-feed in conjugation with manual down feed is so adjusted that the tool will trace the required centre.

Machining splines or Cutting gears: 

By using the indexing mechanism, or index table a gear or equally spaced spline may be cut.