Patent GB-638018-A (GB)
Title: Machine for preliminary cutting and finishing of machine elements
IPC: B23F5/20
Filed: 1947-05-30
Abstract: 638,018. Gear-cutting. FELLOWS GEAR SHAPER CO. May 30, 1947, No. 14444. Convention date, June 6, 1946. [Class 83 (iii)] [Also in Groups XXIX and XXXVII] A machine for cutting gears &c. comprises a cutter-holder 14, a preliminary cutter R and a finishing cutter F rotatably mounted thereon to describe separate orbits spaced to permit each cutter separately to engage a work-piece W on a holder 20, and means for causing each cutter to operate on the work-piece in separate operating relationships, the cutter-holder 14 and work-holder 20 being relatively shiftable for that purpose. The preliminary formmilling cutter R and the finishing generating milling-cutter or grinding-wheel F are rotated to give a constant linear cutting speed by a belt and worm drive and are reciprocated past the work-piece W by hydraulic pistons in a manner similar to that described in Specification 613,971. The form cutter R is fed into the work-piece intermittently by a ratchet device advanced by a solenoid actuated at one end of a stroke of the carriage 14, (see Group XXXVII). The ratchet turns shafts 31, 34, 36, Fig. 2, and thereby a face-gear 38 fast on a threaded member 26 engaged by a non-rotatable nut 25 which, as it rises, lifts a column 22, carrying the cutter slide table 13, towards the work. The table 13, Fig. 1, is guided in ways 391 having upper limit stops 393. The depth of cut is determined by an upper limit switch l<SP>2</SP> which, after a time delay, advances a toothspace counter 198 and starts an electric motor 47 to rotate a pulley 49 and so lower the table 13. A lower limit switch l<SP>1</SP> is then actuated to stop the motor 47, index the work, and, after a time delay, restart the intermittent feed. When all the teeth have been cut, the counter 198, previously set, actuates a switch to initiate the finishing cycle of operations. The work-piece W is mounted on a carriage 18, which, for the finishing operation, is reciprocated by a hydraulic piston 85, controlled by dogs 90, 91 and a valve 187, the cylinder head 89 acting as a left-hand limit stop (see Group XXIX). The rolling movement is provided, as in Specification 554,115, by means of a cam 93 coacting with abutments 94, 95, Fig. 10, which are adjusted by a screwed rod 115 and carried on a slide 106 on the carriage 18. The cam 93 is oscillated in unison with the reciprocations of the carriage 18 by a hydraulic rotary motor and is connected to the work-piece by linkage 98, 99, 100, Fig. 1. During the form-cutting, the cam 93 is held against a solenoid-controlled stop abutting a face 99a of the link 99 by the activated hydraulic rotary motor. When the finishing cycle commences, the stop is withdrawn and the slide 106, Fig. 10, is moved to, and held in, its operative position, determined by a stop 110, by a constant-torque electric motor 114 rotating a pinion 113. The slide 106 then contacts a switch l<SP>3</SP> which starts the constant torque motor 47, Fig. 1, to raise the table 13 against the stops 393 and resets the counter 198 to zero. When all the teeth have been finished, the counter 198, which is advanced by an abutment 199 striking a switch c<SP>12</SP>, actuates a switch to lower the table 13. At its lower limit, the table 13 contacts the switch l<SP>1</SP> to return the slide 106 and, after a time delay, stop the machine with the carriage 18 in its left-hand position ready for a fresh blank to be inserted. Indexing; spindle-mounting.-The work-piece W is carried between a stock 21, Fig. 2, and a spindle 19 which is rotated by a hydraulic motor 92 and carries an index wheel 103, Fig. 7, co-operating with a pawl 102. To index the work during form-cutting, the closing of switch l<SP>1</SP> as the table 13 descends, actuates a solenoid 127 to raise a pivoted arm 123 which depresses a hydraulic valve 125 to actuate the motor 92, and a hydraulic plunger 132 is advanced to trip the pawl 102, thus allowing the motor 92 to index the work through one tooth-space. During generation, an abutment 141 engages the arm 100 at one end of a stroke of the carriage 18, thus raising the arm 123 to open the valve 125 and thereby actuate the motor 92 and also advance a hydraulic plunger 137 which holds firm a dog 138 to trip the pawl 102.