gear rack for Machine Tool Industry

After completion of one or two teeth, the blank and cutter stop feeding and the cutter is withdrawn and indexed back again to its starting position, thus allowing a brief rack cutter of a practical length to be used. Cutter is again fed back again to depth and cycle is repeated. Quantity of teeth is managed by the machine gearing, and pitch and pressure angle by the rack cutter. This technique is utilized for generation of exterior spur gears, being preferably fitted to cutting large, dual helical gears. For generating helical teeth, the cutter slides are inclined at the gear tooth helix angle.
The hob is fed into the gear blank to the proper depth and both are rotated together as though in mesh. One’s teeth of the hob cut in to the work piece in successive order and each in a slightly different placement. Each hob tooth cuts its profile based on the form of cutter , however the accumulation of these directly cuts creates a curved form of the gear teeth, therefore the name generating procedure. One rotation of the work completes the cutting upto specific depth upto which hob is fed unless the gear includes a wide face.

This methodis specially adopted to cutting large teeth which are challenging to cut by formed cutter, and to cut bevel-gear teeth. It is not widely used at present.
In gear planing process, the cutter includes accurate involute rack which reciprocates across the face of the blank and the blank rotates in the correct relationship to the longitudinal motion of the cutter as if both roll with each other as a rack and pinion. Initially the cutter is usually fed into complete tooth depth with cutter reciprocating and blank stationary. Involute shape is generated as the blank rotates and involute rack cutter feeds longitudinally.

In the other technique, both roughening and completing cuts are taken with single pointed tools. The usage of the formed device for finishing is usually impracticable for the larger pitches which are completed by an individual pointed tool. The gear rack for Machine Tool Industry number of cuts required is dependent upon how big is the tooth, amount of share to be eliminated, and the kind of material.