Patent GB-674382-A (GB)
Title: Improvements in or relating to gear cutting machines
IPC: B23F5/12
Filed: 1950-03-24
Abstract: 674,382. Gear-cutting. HARBECK, M., HARBECK, M., STEFFEN, H. W., and STEFFEN, E., (trading as HEIDENREICH & HARBECK). March 24, 1950 [April 4, 1949], No. 7471/50. Class 83 (iii). [Also in Group XXIX] In a bevel-gear cutting machine having a pair of reciprocating tools 55, 56, the movements for operatively engaging and disengaging the tools and the blank are hydraulically effected and these movements and the feeding movement are controlled hydraulically or electrohydraulically. The twin cutters 55, 56, Fig. 1, are carried by a cradle 54, journalled in a longitudinally - movable carriage 53. The gear-blank 57 is mounted on a carriage 58 which may be adjusted manually along a slide 62 which is itself mounted on arcuate guideways for angular adjustment about a shaft 188. Cutter - mounting, -relieving, and - driving mechanism. Each tool, for instance 55, Fig. 13, is adjustably mounted by bolts 95, 90, on a clapperblock 86. The block is tilted at each end of the stroke by a bell-crank 99 actuated by a spring-pressed pad engaging a dragrod. A member 84, to which the block 86 is pivoted, is adjustably mounted by bolts engaging T-slots 104, Fig. 1, in a slide 82. The slide 82 is mounted on a guide which is adjustable about the axis of the cradle 54 by a turn-buckle 262, Fig. 9, the 'adjustment being gauged by graduations 263. The tools are reciprocated by a motor 64, Fig. 4, which is mounted on the carriage 53 and drives, through change-gearing, an adjustable crank 75 mounted on the cradle-axis 59, the crank being connected to the tool-slides 82. 83 bv levers 76. 77. a member 79, Fig. 9, and pivoted sliding blocks 81. The shaft of the motor 64 can be turned for setting-up purposes by engaging a hand wheel 265. Fluid-pressure feed mechanism. The cutter-carriage 53, Fig. 2, is engaged by a floating piston 274. Hydraulic pressure is supplied by two pumps 113 and 114, Fig. 16, driven by a common motor. The delivery of pump 113 is manually -adjustable and a pressure-gauge is fitted on the machine-bed 52 so that the tool carriage movements and rate of feed may be controlled. For a rapid approach, the pump 114 is connected to a chamber 245 to move the piston 274 until it is arrested by a stop-bar 275. Pressure is then supplied to chambers 246 and 247 and the tools advance to cutting position. To advance the tools to working depth, the chamber 246 only is connected to pressure from the pump 113 until a stop 251 contacts a deadstop piston 250. If a roughing cut is to be taken first, the piston is in its right-hand position, and for the finishing-cut is moved to its left-hand position, about 0.5 mm. The carriage 53 carries three dogs 24, 25, 27 which actuate valves 44, 45, Fig. 16. Work- and generating-drives; indexing. The work may be either a gear-blank or a rough-cut gear. In the latter case, when the first of a batch of rough-cut gears has been finished, a device 269, Fig. 1, is adjusted to lie in a tooth-space. It is then swung out of use and serves to repeat the initial setting on subsequent gears. The generating-motion is provided by an electric motor 65, Fig. 1, which rotates a shaft 120 through two pairs of hydraulically-operated clutches. Clutches 131 and 130 control, respectively, the up-and-down rocking movements of the cradle 54. Clutches 149, 144 respectively engage a fast drive from the motor 65 for indexing the blank or a drive incorporating change-gearing for rocking the cradle. The shaft 120 rocks the cradle via a shaft 123, Fig. 6, shaft 171, clutch 173, shaft 172, change-gearing 176-179, shafts 180, 183, worm 184 and worm-wheel 185 fast with the cradle. The shaft 120 also rotates the work via a shaft 124, Fig. 1, shafts 188, 194, a pre-set backlash eliminator, change gears 199-120 and worm gear 205. A dog 212 on a disc 210 coaxial with the work actuates a switch 49 to return the tool-carriage rapidly to initial position and to stop the machine when cutting is complete. The shaft 172, Fig. 6, is screwed to engage a sleeve 175 carrying dogs and cam surfaces controlling the movements of the cradle. A dog 214 disengages the clutch 173 by means of a bell-crank 216 to stop the cradle to allow indexing of the work, and simultaneously a dog 231 actuates a'band-brake to stop the shaft 172. The indexing movement is gauged by a cam disc 220 co-operating with a stop on an arm connected to the bell-crank 216. The disc 220 is attached to a differential gear-housing and is normally at rest. When the clutch is disengaged, however, the disc rotates and prevents re-engagement of the clutch by a spring 48 until the blank is fully indexed by one tooth pitch. A cam-surface 31 controls a valve 47, and an adjustable dog 1 and a dog 2 together control a valve 46. Operation. A cycle for finishing a rough-cut blank is first described. The electric motors are started by a push-button. The pump 114 operates at a pressure of about 300 p.s.i. maintained by a valve 3, Fig. 16, and a back pressure of about 220 p.s.i. is maintained by a valve 17. The cutter-carriage is first advanced rapidly by the piston 274 at a speed of about 6 feet per minute until arrested by the stop 275. The passage 16, Fig. 2, is then connected to the back pressure and pressure builds up in chamber 245. The increased pressure actuates a valve 40 and the piston 272 advances, both sides being connected to pressure. During the advance of the carriage 53, the dog 25 depresses the valve 44 without effect and then the dog 27 depresses it further to cut off feed-pressure from the motor 114. The carriage 53 then continues to feed the cutters into the work at a speed of # th inch to 5 inches per minute, according to the manual setting of the control for the pump 113. When forward movement is arrested by the stop 250, pressure builds up to again move the valve 40 and hence a valve 41 to engage the clutch 144 and rotate the shaft 120. Generating motion then ensues on a down-roll cut. Meanwhile, the shaft 172 advances the sleeve 175, causing the dog 32 to release the valve 47 and pre-set the circuit so that when the dog 1 actuates the valve 46, the clutch 144 is disengaged. Pressure in the chamber 246 is also released and the piston 272 moves back against the piston 274 which is held by the pressure from the pump 114. The cam 24 on the tool-carriage then actuates the valve 45, the clutch 149 is engaged and indexing commences. Sleeve 175 moves to the right and cam 31 actuates the valve 47 to move the piston 272 forward again. Cam-way 24 releases the valve 45 and the cycle continues as before. When the gear is completely cut, the dog 212 actuates the switch 49 during the indexing movement. The switch actuates a solenoid valve 38 and the chamber 245 is connected to the reservoir 243. The tool-carriage then moves back until a limit-switch stops the motors. If a down-roll roughing-cut and an up-roll finishing- cut are to be taken, the valve 43 is turned 90 degrees and moved to its left-hand position. The feed to finishing depth before the up-roll is then controlled by the piston 250. Lubricating machines. A back-pressure valve in the line between the valve 17 and the reservoir maintains a pressure for forced lubrication of the machine.