Patent GB-892347-A (GB)
Title: Improvements relating to machines and methods for running gears together for testingand finishing
IPC: B23F19/02
Filed: 1959-08-05
Abstract: 892,347. Grinding glass. GLEASON WORKS. Aug. 5, 1959 [Aug. 18, 1958], No. 26791/59. Class 60. [Also in Groups XIX, XXII and XXXVII] The finishing of bevel or hypoid gears by lapping, or honing or the like is effected by rotating a pair of gears G, P, in mesh in the presence of abrasive material or a gear and mating hone and, during rotation, imposing a relative oscillation between them about an axis which is perpendicular to their axes and passes through the mesh zone in approximately tangential relation to them, thereby shifting the tooth bearing from end-toend of the teeth; provision may also be made for relative reciprocation between the gears in time with the oscillatory movement, the reciprocation being in a direction perpendicular to the axis of oscillation 32, Figs. 1 and 2, so that, during the lateral shifting of the tooth bearing, the backlash between the teeth and the position of tooth bearing between top and bottom of the teeth may be controlled. Figs. 19 and 20 show, respectively, the effect of these motions and the manner of applying them to meshing spiral bevel gears G, P. The pinion P, Fig. 20, if swung clockwise about axis 32 moves the centre of the bearing area 151, Fig. 19, along a diagonal line 152 towards the toe or small end of the tooth or towards the heel if swung oppositely. The bearing may however be kept along a median line 155 by simultaneously providing an appropriate amount of horizontal movement of the gear G towards or away from the axis 32 along the line 156, Fig. 20; an "in" motion of the gear shifts it from point 154 to 158 and "out" from 153 to 157. As these motions both affect the backlash between the gears, the pinion is also reciprocated, during oscillation, along the line 159, Fig. 20, to maintain the backlash approximately constant. During reverse running, when the bearing area is on the other flank of the tooth at the centre point 161, Fig. 19, a reversal of the above-described conditions becomes operative and the centre position of the gear axis 168, Fig. 20, may have to be shifted inwards or outwards to 168<SP>1</SP> or 168<SP>11</SP>. A machine for finishing or testing gears in accordance with the invention comprises a frame 20, Figs. 1 and 2, horizontal parallel pairs of guide rods 21 and 29 for slides 22 and 28 arranged for reciprocation mutually at 90 degrees. A housing 25 for the spindle 26 of the gear G is mounted for vertical adjustment on a column 23 capable of angular adjustment about a vertical axis 24 to permit the mating gears to run at angles larger or smaller than 90 degrees. A plate 31 is angularly movable on the slide 28 about the vertical axis 32. The pinion spindle 37 is belt driven by a motor 42 and is journalled in a housing 35 mounted for horizontal adjustment in ways 34 and 36 of a plate 33 slidable on plate 31. Handwheels 39, 41 operating slide-adjusting screws 100 and 46 respectively enable the gears G, P, to be brought into running position with their mean pitch point on the axis 32, and the pinion to be withdrawn to the position P<SP>1</SP>, Fig. 1, to permit loading. The screw 46 is reciprocable, independently of the handwheel 41, by a bellcrank 53, Fig. 3, which is swung about a fixed pivot 61 by a crank-pin 52 rotatable about the axis 51a, Fig. 4, of a shaft 51 by a motor 49. Epicyclic reduction gearing 54-58 is interposed between motor 49 and the shaft 51. A slot 59 disposed between the upper and lower parts 63 of the bell-crank 53, is engaged by the crank-pin 52 which, when swung to a position 51, causes the screw 46 to move to the right thereby withdrawing the slide 28 to the loading position. Spring-loaded hemi-spherical plugs 64, permit a limited amount of relative motion between the inner and outer portions of the bell-crank arm in the event of an obstruction in the path of the slide 28, such motion opening a switch 68, 69 in the control circuit of the motor 49. The slot 59 is preferably so shaped that the motion of the screw 46 is in constant velocity ratio to the angular motion of the pin 52. A similar bell-crank mechanism provides a constant velocity ratio motion between a crank-pin driven through a reduction gear by a motor, and the screw 100 whereby the slide 22 and gear G is reciprocated. A belt-driven generator 45 provides a load for the gear G. Figs. 3 and 13 show the mechanism for establishing the backlash between the gears G and P. An externally V-grooved sleeve 73 surrounds and is keyed to move with a nut-portion 74 threaded on the screw 46, a similar threaded portion 75 being separated therefrom by a backlash take-up shim 76, the assembly having limited sliding motion within a bore in a block 77 secured to the slide 28; a spring 79, Fig. 3, urges the block and slide to the left to a limiting position determined by a stop 81. A spring-loaded plunger 82, Fig. 13, slidable in the block 77 may be pressed by a cam 84 and lever 83 into engagement with the V groove to move the slide 28 to the right to a definite position relative to the sleeve assembly 73, 74, 75 against the action of the spring 79; a second cam is operated by the lever 83 to operate a switch 80 to prevent the motor 49 from running whilst the plunger 82 is engaged. The block 77 has secured to it a clamp which encircles part 75 and grips it when a lever 88, Fig. 2, is operated to close the clamp and also to close a switch in the circuit of the motor 49. The block 77 also carries a dial indicator 96, Fig. 3, which contacts an abutment screw 97 on the sleeve 73. the core 98 of a transducer-type transformer is secured to the end of the slide-adjusting screw 46 whose coils 99 are mounted on the machine frame 20. Backlash is established by the following operation:-After locking the block 77 in relation to the sleeve assembly 73, 74, 75 by the lever 83 the master gears G and P or equivalent gauging devices are mounted on the spindles and the motor 49 is run to swing the bell crank 53 counter-clockwise to the position approximately shown in Fig. 3. The handwheel 41 is then turned to advance the slide 28 until the gears are in their correct running position, when the master gears will have the correct amount of backlash. The indicator gauge is then set to zero, the slide 28 is retracted and the master gears are replaced by gears to be run together. The lever 83 is turned to release the plunger 82 and the slide 28 is advanced by running the motor 49 to bring the gears into a position of mesh without backlash, the final part of the advance being under the control of the transducer 98, 99, the full engagement of the gears arresting further motion of the slide 28 and block 77 slightly before the advance of the sleeve 73, 74, 75 has ended, thereby further compressing the spring 79. The clamp 75 is then tightened by moving the lever 88 and closing a switch in the circuit of the motor 49 which reverses it to withdraw the slide by an amount which has been pre-determined and is measured by the control system, including the transducer 98, 99 to provide the correct amount of backlash. Deviation from standard, so far as it affects the mounting position of the gear G may be read directly on the indicator 96. When used for testing without backlash the indicator may be used in known manner to indicate eccentricity or other errors; a pick-up device 101, Fig. 3, may be associated in known manner with the indicator for remotely recording such errors. A reversible motor 105 acting through a reduction gear unit 106, Fig. 18, drives a crankpin 107 about an axis 108 to oscillate the plate 31 about the meshing point 32 of the gears G and P. The cam slot 111 is preferably shaped to provide a constant velocity motion of the assembly 31, 35, and 109 about the axis 32. The coil 112 of a transducer is secured to the slide 28 and its core 113 is carried on a bracket 114 secured to the plate 31. Three ball-bearing assemblies, 115 Fig. 1, support the plate 31 for swinging action about the axis 32. A co-axial pivot pin 126, Fig. 2, may be provided, but for mounting gears of large diameter the pin 126 is eliminated and an alterna tive arrangement Figs. 14-17 (not shown) is used in which an arcuate slot in a member secured to the plate 31 engages a pair of rollers mounted on a fixed pivot secured to the slide 28, to guide the movement of the plate 31 about the axis 32. The grooved member may be adjustably attached to the plate 31 to provide for the adjustment of the location of the axis 32. The control system Figs. 21 and 22 (not shown) includes a cam disc 135 Fig. 4 keyed to the upper end of the motor driven shaft 51, the disc being shown in the position occupied when the slide 28 is in the "advanced" position as in Fig. 3. Fig. 6 shows the disc position relative to the switches 144, 145 and 139, 141, when the slide is in the withdrawn or loading position. The upper cam lobes 136, 137 operate, through rollers 138, the upper switches 139 and 141 respectively and lobes 142, 143, operate the lower switches 144 and 145 respectively.