Patent GB-515204-A (GB)
Title: Improvements in or relating to gear finishing machines
IPC: B23F19/06
Filed: 1938-03-31
Abstract: 515,204. Gear-cutting. NATIONAL BROACH AND MACHINE CO. March 31, 1938, No. 9891. Convention date, April 5, 1937. [Class 83 (iii)] In a method of and machine for finishing gears, the gear member to be finished is run in mesh with a plurality of conjugate gear-like tool members arranged on axes which cross the axis of the gear member at an angle between 3 degrees and 30 degrees, one of the members being driven to drive the others and the tool members being reciprocated relatively to the gear members to distribute the finishing action over the face width of the gear member. In one form a cluster gear 16A, 16B, is mounted between head and tail centres 13, 15 respectively and may be driven from a motor 17 through a driver 13B. The gear-like tools 19, 20 preferably mounted on opposite sides of the work are mounted on inclined axes in housings 21, 22 mounted in reciprocable carriages 23, 24 guided by ways parallel to the work axis and formed on heads 25, 26 which are adjustably secured to the frame. Reciprocation of the carriages is effected from motors 27, 28. The motor 27, Fig. 2, is connected through couplings 27B and worm gearing 29, 34, to a lead screw shaft 36, coacting with a nut 28A on the head 25, the reversal being determined by suitable limit switches. In some cases the tool 19 may be driven from the motor shaft through worm gearing 37, bevel gearing 41, clutch 47, and gears 44. The tool 20 may be reciprocated and if desired, positively driven from the' motor 28 through similar gearing to that above described. For varying the angular setting beween tool and work axes the tool housing may be rotated by hand-operated worm gearing about the vertical axis of shaft 39 forming part of the tool driving train. Each of the heads 25, 26 is adjustably mounted on an auxiliary slide 55, the adjustment being effected by a screw - spindle 66 to set the tools to the proper depth. The auxiliary slide is supported on cams 57, 58 on rotatable hangers 59 which may be rotated to cause the cams to feed the tools to the work and withdraw them at the end of the operation. The cams are rotated by a motor 67 controlled by a lever 68 which may be oscillated to cause ratchet mechanism to rotate a disc 75 so that a dog 76 actuates a switch 77 in the motor circuit. A shaft 74 is connected to the cams by gearing 80. An overrunning clutch is provided at 78. After the cams have rotated sufficiently to feed the tools a second dog stops the motor. At the end of the carriage traverse the motor 67 is energized to rotate shaft 74 until another dog opens switch 77. This is repeated until the tools are fed to depth at which time a switch 84 is opened by a cam 85 on shaft 74. Subsequent movement of lever 68 rotates shaft 74 and separates the tool heads. In some-cases a single gear may be acted upon simultaneously by two tools arranged on opposite sides of the work. The tools may be similar or one may be for roughing and the other for finishing. The inclination to the work axis is preferably greater in the case of the roughing cutter and the rates of feed, and diameters of the cutters may also be different. The roughening tool, Fig. 11, may have narrow lands as shown while the finishing - tool has lands and recesses of equal widths. When operating simultaneously with roughing and finishing cutters the roughing- cutter is set slightly ahead of the finishing- cutter in longitudinal direction. Also the roughing-cutter is in-fed at the end of each of two successive longitudinal movements and then has no further feed while the finishing-cutter is in-fed after each of four successive longitudinal movements. This cycle may be modified. In some cases the roughing-cutter may be stopped at the end of each stroke until the finishing- cutter has caught up with it. In other cases the roughing-cutter may be withdrawn while the finishing-cutter performs its final cycle. The invention may also be applied to lapping and burnishing operations, either the work or tool being driven. In another modification, Fig. 13, two aligned gears may be each acted on by two tools. A gear having a bevelled face. 91 which modifies the otherwise involute form may first be hobbed oversize as at 92 and the bevel then produced by suitable roughing and finishing cutters the former of which reduces the work to the form 95. In a modified form of machine, Fig. 16, the work is reciprocated instead of the cutters. A motor 117 carried on a bracket secured to the work slide.100 drives a shaft 104 connected through worm gearing 105, Fig. 18, shaft 107 and change gears 113 to the work driving spindle 115. The shaft 105 is also connected through worm gearing 118 bevel gearing 123 and gears 126 to a lead screw 129 engaging a fixed nut to reciprocate the work slide. Suitable limit switches are provided to reverse the movement of the work slide.