Gear Shaping – Gear Shaper Working ,Principle – Gear Manufacturing

Gear Shaping:

A ‘generated’ surface, whether it is curved or straight, is produced by continuous motion of a point, a line or a surface. The direction in which the generating point travels determines the shape produced. The simplest example is the generation of a cylinder on a lathe. The cutting point of the tool generates a circle when the work piece is rotated. As the tool is led axially, cylindrical component is produced.

Read More : Types Of Gears, Material Used For Gears,Design Specification and Application

gear shaping process
gear shaping process

The geometrical accuracy of the circular component depends on:

(a) The trueness of the work piece rotation.

(b) Parallelism of the tool movement with the work- spindle axis.

(c) The effect of tool wear.

It does not depend on the form of tool profile. Besides, the process is continuous.

Gear Shaper machine

In gear shapers, the above generating principle is applied in the following way

The cutter is hardened disc shaped and slightly dished at the bottom (ground with top rake and clearance) to facilitate cutting. The teeth have desired tooth profile and pressure angle.

gear shaping machie
gear shaping machine

The cutter is reciprocated with the required cutting speed for stock removal along the face of the work piece, and is gradually fed radially to plunge if for correct teeth depth by means of a cam. A relieving mechanism enables the cutter to clear the work on non cutting or return stroke.

The continuous generation motion is obtained by feeding cutter to full depth and rotating the cutter and the work piece slowly in the exact ratio of their respective number of teeth by means of a chain of gears including change gears. The cutter is considered as the driving gear and the work piece as the driven member, exact transmission of motion being effected by an external link of gear train.

The work piece gear is fully generated when the cutter has plunged to correct tooth depth (set previously) into the work piece and the teeth are cut fully and uniformly over the entire periphery of the work piece gear. The machine comes to rest automatically after the work piece gear is fully cut.

gear shaper principle
gear shaper principle

The cutting action of a pinion type of cutter to generate a gear is shown clearly in Fig. . The principle of cutting gear by the generating method has the advantage that with a particular module of DP cutter it is possible to cut accurately gears having identical module or DP, but different number of teeth. This makes the generating process functionally superior and economical for the manufacture of gears.

Thus in brief, it could be seen that since an involute gear will roll with any other involute gear of same normal base pitch and hence this principle has been utilised in the gear shaper (a method of gear manufacture). In this cutter is made in the form of pinion provided with relieved cutting edges, both cutter and work are given rotary motions about their respective axes to simulate the conditions obtaining, had both members been complete gears rolling together at the correct centre distance.

This is achieved by gearing the cutter to the work in the same ratio as the numbers of teeth in the cutter and the finished work. Cutting is effected by imparting axial reciprocating motion to the cutter coincident with its rolling action, the length of stroke of the ram being slightly more than the width of the blank.

Advantages Of Gear Shaping :

(1) The gears produced by this method are of very high accuracy.

(2) Both internal and external gears can be cut by this process.

(3) Non-Conventional types of gears can also be cut by this method.

Disadvantages Of Gear Shaping :

The production rate with gear shaper is lower than hobbing. There is no cutting on the return stroke in a gear shaper. Worm and worm wheels can’t be generated on a gear shaper.

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