Patent GB-505410-A (GB)
Title: Improvements in or relating to machines for shaping spur gears
IPC: B23F5/14
Filed: 1938-08-26
Abstract: 505,410. Gear-cutting. FISCHER, G. Aug. 26, 1938, No. 25183.' Convention date, Aug. 28, 1937. [Class 83 (iii)] A machine for generating spur gears by means of a reciprocating rack cutter having a length not less than the circumference of the blank has the rolling motion controlled by a master spur gear mounted on the blank spindle and rolling on a master rack, the blank spindle being mounted on a slide driven by reversing gearing -controlled by the slide. A motor 15 drives through bevel gearing 13 and spur gearing 7 .. 10 a crank 4 which reciprocates the ram 2 carrying a clapper plate fitted with a swivel holder 52 for a long rack tool 51 which cuts all the teeth of the blank in one rolling movement. A branch train from the shaft 6 comprising gears 16 ... 19 and 21 ... 23 is connected through reversing bevel gearing 27 and gears 31 to a screw shaft 33 which traverses the work slide 36 along guides 71 carried by a support 42 which is in turn movable on transverse guides 73 by a hand wheel 74. The slide 36 is provided with a large vertical bearing for the rotatable worksupport 37 on which the work piece 50 is secured. A mandrel 38 extending downwards from the worksupport carries an interchangeable master gear 40 of ,the same pitch circle diameter as the blank. The master gear engages a long rack 41 adjustably secured to the support 42 and moved into correct mesh with the master gear by means of a backing wedge 43 adjusted by a screw 44. Preferably a number of wedges of different thickness are provided. The hand-wheel 74 is rotated to bring the work into the required position and as the slide 36 is fed by the screw 33 the master gear rolls on the rack to impart the correct rolling movement to the work. The reversing-clutch 30 is returned automatically by means of a rod 63 carrying abutments 64 which at either end of the slide travel engage a lug 67 on the slide to restore the clutch to neutral position. For starting the movement a control lever'54 is moved to one of the extreme positions a, b thereby causing a pinion 66 to operate the rod 63 and move the clutch to one of its operative positions. The lever 54 also rotates a disc 55 having notches 56 which, in the positions a, b of the lever are engaged by the end of a. lever arm 57 to release the button 58 of a switch 59 controlling the motor switch 62, thereby starting the motor 15. At the end of the roll the clutch 30 is moved to neutral by the rod 63 and the lever 54 is moved to position c thereby stopping the motor. The work piece is. now replaced and another blank cut during the return roll. Alternatively the same blank may be rolled in both directions past the tool, the first roll being made at high speed for a roughing cut and the return roll at lower speed for a finishing cut. In this case the reversing gear includes change gears 31, 31<1>, 32, 32<1>, Fig. 3, arranged to give different speeds in the two directions of roll. For cutting helical gears the ram guides are set over to the required angle by a swivel member 70, the tool preferably having inclined teeth and being set by the plate 52 in a position parallel to the rack 41.