Patent GB-825648-A (GB)
Title: Improvements in or relating to a machine for grinding spur or helical gears
IPC: B23F5/04
Filed: 1956-09-10
Abstract: 825,648. Gear-grinding. REISHAUERWERKZEUGE A.G. Sept. 10, 1956 [Nov. 18, 1955], No. 27601/56. Class 83 (3). [Also in Group XXIII] A hobbing-machine for grinding spur and helicalgears in which the work 10 is moved axially relatively to the hob 9 while the distance between the axes is varied to produce either conical or crowned-gears, comprises a template 38 fixed to the work-slide 4 for producing each of the required movements. The work-slide 4 is mounted on a cradle 3 which can be adjusted angularly by hand-operated worm-gearing 6. The cradle is mounted in a support 2 which can be tilted about an axis X by an eccentric disc 35 controlled by a lever 37. The lever 37 is held against a projection 151 on a piston 147 by the overhanging weight of the work-slide. The piston 147 is engaged by a control valve 145 which bears on a follower-rod 143 engaging an adjustable curved template 141 or a straight-edged plate 140, the plate and template being relatively arranged so that a greater or lesser length of the plate 140 is exposed according to the length of tooth which it is desired to leave uncrowned. A synchronous motor 12 on the cradle rotates the work through differential gearing 15 which is locked when plain spurs are ground, and gears 22, 24, 27. Generating helical gears.-When grinding helical gears, a gear is mounted on a shaft 46 in place of a locking disc 48, and is connected by change-gears to a gear 52 which rotates a gear 54 meshing with a rack 55 on the workslide. The work-slide is reciprocated by a piston 56, under the control of switches 622, 623, and dogs 60, 61, the piston being supplied with pressure fluid from a variable delivery pump 58 driven from the gear 24 by a gear 59. The hob 9 is driven by a coaxial synchronous motor. The hob-slide 70 is adjusted manually by rotating a screwed shaft 791 by a handle 75 through gearing 76, 77 and is fed by a piston 90 in which slides a control valve 92. The end 93 of the valve 92 engages a piston 95 sliding in a cylinder 96 pivoted at 99 and carrying an arm 982 engaging a piston 100. Three pumps 110-112 provide pressure-oil which is distributed via valves 124, 125 in a control-block 119, and cocks 121-123. The lever 126 controlling the cock 121 has three positions, respectively to, provide for fast upward movement of the work-slide during setting-up, for operation, and for stopping the slide at any moment. Similarly, a lever 127 for the cock 122 provides for machining cylindrical, conical or crowned gears. A lever 128 for the cock 123 moves the hob to working- position, or to work-unloading position. In the setting shown, the hob is in working-position and the slide 4 is being moved upwardly by the piston 56 at a feed-speed determined by the pump 58. When the slide reaches its upper position, the dog 60 actuates the switch 622 to energize a solenoid 132 and move the valve 125. Pressure is then directed to the piston 100 causing it to swing the lever 982 upwardly. The control valve 92 follows the movement under the control of a spring 94, and the consequent movement of a groove in the valve relatively to the end of the piston 90 causes the piston to follow-up, thus withdrawing the hob. The slide 4 is also reversed and moves down at a rapid-rate until the dog 61 actuates the switch 623 to initiate a further feed-stroke, and to move the hob back to working position. Generating conical gears.-For grinding conical gears, the lever 127 is moved to its central position. The result is that, when the workslide moves upwardly, a piston 85 bearing against the template 38 moves to the left and displaces fluid through closed lines 175, 159 to cause upward movement of the piston 95. Consequently, the control valve 92 is moved to the right and feeds the hob inwardly. When the switch 622 is operated to reverse the slide 4, it also returns the pistons 85, 95 to their initial positions. Crowning.-For crowning gears, the lever 127 is moved to position " F." As the work moves upwardly, the template 38 causes the piston 85 to move, resulting in a corresponding movement of a piston 136 attached to the plate 140. The template 141 and plate 140 are thus traversed past the follower-pin 143, which allows a " follow-up " movement between the control valve 145 and piston 147 to rock the work-slide about the axis X, thus crowning the teeth. Alternatively, the template 141 may be convex to give a hollow profile to the teeth of shaving cutters. In a modification, the hob is moved instead of the work, and the template 38 is carried on the hob-slide. The hob may be rocked instead of the work, and the work may be moved laterally, instead of the hob.