Patent GB-819622-A (GB)
Title: Improvements relating to grinders for truing gear cutters
IPC: B24B3/02
Filed: 1957-12-04
Abstract: 819,622. Grinding; trueing grinding wheels. GLEASON WORKS. Dec. 4, 1957 [Dec. 6, 1956], No. 37730/57. Class 60. [Also in Group XXXVII] A machine for trueing gear cutters C, Figs. 1 and 2, particularly those having angular side profiles, comprises a cutter slide 22 on a frame 20, a grinding wheel W on a slide 69 movable rectilinearly on the frame in the direction of the wheel axis 68 between a first stop 78, 79, Fig. 6, which is fixed and determines the wheel dressing position, and a second stop 81, 83, which determines the grinding position and is adjustable in the direction of the wheel axis to enable the profile dressed on the wheel to be brought into coincidence with the side cutting profile of the cutter, and a profile dresser for the wheel on a slide 92, Fig. 7, rectilinearly adjustable in a direction perpendicular to the wheel axis 68, the dresser being angularly adjustable on the slide 92 about a dresser adjustment axis 103 which is perpendicular to the wheel axis and the direction of adjustment of the dresser slide. The dresser has a tool T, which is preferably diamond-tipped, carried on an L-shaped arm 107 secured to a piston rod 108, Fig. 8, which is axially movable in balls 112 in a housing 104 by means of a hydraulic piston- and-cylinder device 114, 115 and rockable about its axis 113 under the control of a cam 117 and follower 111 urged into contact by a spring 116. The dresser is angularly adjustable about the axis 103 to a position wherein the axis 113 of the piston rod corresponds with the pressure angle of the cutter, which position can be determined by a pin 121 on the dresser housing engaging a gauge piece 122 disposed on a V-way on the slide 92 and co-operating with a removably-secured micrometer 126; the dresser is clamped in its adjusted position by screws 105. The dresser can be adjusted in a direction perpendicular to the axis 68 of the wheel and the axis 103 to bring the tool T into engagement with the grinding wheel, when the latter is in its upper position determined by the stops 78, 79, by a hand-operated screw 96 which is axially-secured to the frame of the machine and co-operates with a nut 97 secured to the dresser slide. The end 98 of the screw 96 is slotted and receives a tapered screw 99 which is axially movable by rotation of a knob 101 to expand the end of the screw and thus lock the slide in its adjusted position. During the first part of the upward, dressing movement of the tool T caused by fluid entering the lower part of the cylinder 115, the cam prevents rotation of the piston rod 108 so that the tool dresses the straight portion W<SP>1</SP>, Fig. 25, on the wheel, which afterwards grinds the portion C<SP>1</SP> on the cutter C, until the tool reaches the height of the dresser adjustment axis 103, after which the cam imparts a rotational movement to the rod 108 and arm 107 to cause the tool to dress the portion W<SP>2</SP> on the wheel which will afterwards grind the portion C2 on the cutter ; a valve in the hydraulic circuit permits a quick return of the tool to its lower reset position. The slide 69, Fig. 6, carrying the grinding wheel W, which is belt-driven from a motor 71, is vertically movable from its upper position, defined by the stop 78, 79, to its lower position, defined by the stop 81, 83, under the control of a piston- and-cylinder device 75, 76. The lower stop 81, 83 can be set by a gauge 189, Fig. 23, removably secured to a pad 184 on a slide 69 of the wheel by an eccentric 187 and T-bolt 185 ; the gauge is axially adjustable relative to its housing 182 and can be set by a micrometer 194, Fig. 24, on a block 183 so that when the gauge is clamped to the wheel slide, its distance H, Fig. 25, from the junction between the surface W<SP>1</SP>, W2 on the wheel, which coincides with the dresser adjustment axis 103, is equal to the distance H<SP>1</SP> required between the tips of the cutter blades and the junction between the surfaces C<SP>1</SP>, C2 on the cutter. The stop 81, Fig. 6, is axially adjustable by means of a screw 82, which may be rotated by a wrench applied to the end of a rod 87, in a nut 84 until the gauge contacts the tips of the cutter blades, the screw then being secured in its adjusted position by a handoperated clamp 85 and the gauge removed from the slide. The cutter is clamped to a face plate 23, Fig. 23, by means of a disc 26, centre 25 and bolt 27 and rotated about its axis 24 by a motor 28, Fig. 2, and belt-drive 31. The motor is pivoted about a vertical axis and can be moved from a drive position, wherein the belt is tight, to a free position, wherein the belt is slack, by a handle 32 so that the cutter cam can be driven or freely rotated during setting up. The face plate and motor are mounted on the cutter slide 22 which can be moved from a loading to a grinding position by a piston- and-cylinder device 33, 34, Fig. 3. In the grinding position, the cutter can be fed into contact with the grinding wheel until a narrow land is ground back of the edge C<SP>1</SP> of the cutter by a coarse and fine adjustment device controlled by a handle 42. In the coarse adjustment position, defined by the position of handle 59 on a screw-threaded member 56, a clutch member 51 engages a conical member 52 secured to the handle 42, and rotation of the handle and its shaft 47 causes an internal gear 44 to rotate with the shaft 47 and a planet gear 45 and rotate a second internal gear 43 on a nut 38 which imparts axial movement to a screw 36 secured to the cutter slide. In the fine adjustment position, the member 56 urges the clutch member 51 to frictionally engage a ring 49 which, in turn, frictionally engages a part 58 of the frame to clamp the gear 44 against rotation. Rotation of the handle 42 and shaft 47 rotates the planet gear 45 around the gear 44, which has 99 teeth, and the gear 43, which has 100 teeth, to impart a fine adjustment to the slide 22. Backlash between the screw 36 and nut 38 is prevented by a spring-urged nut 63 keyed to the nut 38 and dust, &c. is excluded by a flexible seal 66. A graduated scale is provided on a dust cover 61. The cutter slide 22, wheel slide 69 and dresser slide 92 preferably employ opposed V-grooves 21, 73, Fig. 1, receiving roller bearings alternately disposed with their axes at 90 degrees to each other. The piston-andcylinder devices 114, 115, 33, 34 and 75, 76 are operated by manually-controlled valves 132, 133, 134, respectively, on the frame of the machine. A vertically-movable bar controlled by a lever 147 connected to the wheel slide 69 interconnects the valves and prevents the dresser operating except when the wheel slide is in its upper position (the cutter slide returning to the loading position when the wheel slide is down) and the wheel slide from being lowered while the dresser is in its lower position, an indicator light controlled by a microswitch 179, Fig. 8, actuated by a spring-urged plunger 181 being illuminated except when the dressing tool is in its upper position. The fluid supply to the piston-and-cylinder devices 33, 34, and 75, 76 is restricted so that the speed of movement of the slides 22, 69 is reduced towards the end of the strokes of the pistons 34, 76 by the pistons closing the main supply lines to the cylinders and the fluid being diverted through valves which restrict its flow to the cylinders. A safety valve is incorporated which, in the event of failure of the fluid pressure, causes a plunger to engage a recess in the vertically-movable bar to hold the wheel slide in its upper position. The pump supplying the fluid pressure, and the motors 71 and 28 driving the wheel W and cutter C, are controlled by switches 166, 168, 171, respectively, the latter pair being rotatable to one of two positions to control the direction of rotation of the motors depending on whether right-hand or left-hand cutters are to be trued.