Patent GB-521382-A (GB)
Title: Improvements in or relating to machines for producing gears
IPC: B23F5/14
Filed: 1939-01-06
Abstract: 521,382. Gear-cutting. MAAG GEAR-WHEEL & MACHINE CO., Ltd. Jan. 6, 1939, No. 497. Convention date, Jan. 7, 1938. [Class 83 (iii)] A machine for cutting gears on the rolling generating principle wherein the various phases of a generating cycle are controlled by a rotary controller which rotates once during each cycle, as described in Specification 109,256, [Class 83 (iii)], is provided with a time control which interrupts the controller drive for a predetermined time during each cycle, thus permitting continuation of the movement, such as the forward or backward rolling movement, which was in operation at the instant of interruption of the controller drive. In this way the machine may be readily adapted for the cutting of a number of teeth at each cycle using a long rack tooth cutter. The blank 4 is carried on a rotary table 3 carried by a slide 2, to roll the blank past a reciprocating rack cutter 6 driven from a crankshaft 9. A branch train from the shaft 9 including bevel gearing 13, adjustable crank mechanism 15, connecting rod 16, and ratchet mechanism 18 imparts intermittent movement to a wheel 20 geared to an auxiliary shaft 22. This shaft is connected through gears 41, shaft 42, gears 43 and change gears 48 to the table traversing screw 44. A branch from this gearing including gears 68 clutch 65 and change gears 49 drives the table-rotating worm 47. In addition to the uni-directional drive from the shaft 19, the shaft 22 has an additional drive in the opposite direction. A wheel 23 on shaft 22 drives a loose gear 24 coacting with oppositely-acting splined clutch members 27, 27a on shaft 25. During the forward roll the shaft 25 may be stopped by means of a lever 28,actuating the clutch 27. Shaft 25 carries loose gears 29, 31 which may be coupled to the shaft by oppositely-toothed clutch members 38, 39, and which drive directly and through an intermediate gear 32, gears 30, 33 on a shaft 34 geared to the controller drum 37. At the end of the forward rolling movement the tool ram is stopped by a cam 51 on the control drum acting through a linkage on a clutch in the drive of shaft 9. Thereupon another cam 55 engages a clutch part 57 with a constantly-driven wheel 58 to impart the auxiliary drive to shaft 22 in the opposite direction from the intermittent movement derived from shaft 19. The motion of shaft 42 and the rolling movements are thus reversed. During this reversal a cam 62 acts through linkage 64 to disengage clutch 65 and interrupt the table rotation to index the blank while the return movement of slide 2 continues. A cam 55a then re-engages clutch parts 57, 57a and stops the return rolling movement. A short rolling movement at reduced speed in the forward direction then occurs to take up lost motion. For this purpose a cam 83 engages a constantly-driven clutch part 88 with a loose gear 90 engaging a gear 91 integral with gear 21. When an extended rolling movement is required the control drum is stopped during part of such movement. For this purpose each clutch member 38, 39 is disengageable.by a lever 71 coacting with a cam plate 72 rocked by a link 73 coacting with cam-grooved stops adjustably mounted on a disc 80 driven from the shaft 25 which is rotated alternately in opposite directions by the shaft 22. When either of the stops engages the link, the clutches 38, 39 are disengaged and the controller stopped. For single-toothed indexing the machine cycle is as follows. Starting from 0, Fig. 5, the controller rotates intermittently 4/10 of a revolution for the operative, roll. The tool is then stopped, clutch member 57b engaged, and shaft 22 reversed, and the blank rolled backwards for 1/20 of a revolution of the controller at the end of which the table is stopped. During the following 4/10 of a revolution of the controller the slide 2 is returned without rotation of the blank after which the clutch 65 is again engaged. During the next 1/20 revolution the blank, now indexed, completes its return roll. At the end of this step the shaft 22 is reversed and during the ensuing 1/10 revolution the blank is rolled forward to take up play thus reaching the point 0 in readiness for another cycle. If a prolonged roll is required say for cutting nine teeth per cycle the controller is stopped at point A in the forward roll, the stop 81 being set to come into operation at this point. At the end of the required roll the stop 81a re-engages clutches 38, 39 and the controller movement is resumed. On the return roll the controller is again stopped at point A, while indexing through the additional eight tooth spaces after which it is restarted and the indexing through the remaining one tooth space. In some cases a single-tooth rack tool or a pair of inclined grinding wheels may be employed. For such working an extended rolling movement is required by the indexing is only through a single tooth space. The stop disc is angularly displaced on its shaft so that the controller is stopped at point B<SP>1</SP> in the return roll and the usual one-tooth indexing occurs during the step III of the controller cycle. The corresponding interruption on the forward roll occurs at B.