Generating Straight Bevel Gears

Generating Straight Bevel Gears

Generating Straight Bevel Gears - Straight tooth bevel gears are commonly cut by bevel gear generator employing two reciprocating tools. Referring to Fig. (c), main drive 11, powering the operative units of the generator, is located at the lower part of base 9. Mounted on a flat surface of the base are the main units: work head 5 for clamping gear blank 4 and cradle 1, oscillating in the annular ways of the cradle column.

Operation of Bevel Gear Generator

Cutting Tool

Straight Bevel Gear Generator

Cradle I carries tool slides 2 which reciprocate radially toward the centre of the gear blank. The oscillating motion, or role, of cradle 1 about its axis is the generating motion. The workhead with the gear blank is set to the required angle with the swinging base 8 on the sliding base.

By means of gearing 6, the gear blank rotates during the generating process in timed relation with cradle 1. In going over from the machining of one tooth to the next, tools J are retracted and the gear blank is indexed one tooth by mechanism 7. Sliding base 10 advances and withdraws the blank to and from the tools.

For cutting gear teeth, refer to Fig. a and c.

(i) The gear blank has got a rotary motion,

(ii) The cutting tools reciprocate,

(iii) The cradle oscillates or rolls.

Figs. (a) and (b) illustrate the operation of two tools in cutting a straight tooth bevel gear and the general view of a tool for that purpose. Gear blank, 4, and cradle, 1, are imparted interrelated rotating movements forming the generating roll movement, while the tools, 3, reciprocate across the gear blank in a series of cuts as they roll together with the blank.

This produces the profile of tbe tooth. At the end of each generating roll, the blank is withdrawn automatically from the tools and the cradle and work spindle roll back to start the next tooth after the blank is indexed.