Patent GB-577090-A (GB)
Title: Improvements in and relating to grinding-wheels and the dressing thereof
IPC: B24B53/085
Filed: 1944-05-03
Abstract: 577,090. Dressing grinding - wheels. GLEASON WORKS. May 3, 1944, No. 8387. Convention date, July 28, 1943. [Class 60] A grinding - wheel having active side and tip surfaces, for example, an annular grinding-wheel used for the grinding of spiral bevel and hypoid gear-wheels, has the side and tip surfaces dressed to give any desired finish thereto, for example, the inside and tip surfaces may be dressed to the same finish, whilst the outside surface is dressed to a coarser finish. The apparatus for effecting the dressing comprises three dressers carried on the grinding-machine by an adjustable mounting, each dresser being movable into and out of operative position and movable, whilst in operation, across the surface to be dressed, the movements being effected by hydraulic pressure and controllable to give speeds which produce the required finish on the wheel surfaces. As shown, the grinding-wheel W has active outside and inside surfaces 31, 32 respectively, and a tip surface 33, and is carried by a spindle 25 journalled in a sleeve 26 having a flange 29, on which is angularly adjustable a ring 35 locked in position by a plunger 36. The member 35 has a lateral extension 40, on which is adjustable a slide 41 movable by a screw 42 and pivotally mounted on the slide 41. by a hinge pin, is a bracket 50. Mounted on the bracket for movement at right angles to the direction of adjustment of the slide 41 is a plate 55 movable by a screw 56, and mounted on the plate 55 for movement at right angles to the directions of adjustment of the slide 41 and plate 55 is a plate 65 movable by a screw 68 ; the slide and plates may be locked in adjusted position by T-slots, and bolts and verniers and scales are provided for setting the slide &c. The plate 65 has mounted therein a housing 75 adjustable angularly by a worm 76 engaging a worm segment 79 on the housing, the housing being guided by a tongue, engaging an arcuate groove 80 in the plate 65, and clamped in adjusted position by a tongue 81 ; a vernier 84 and graduations are provided for setting the housing. Journalled in the housing 75 are two shafts 90, 91 with their axes inclined at an angle corresponding to that between the wheel surfaces 31, 32 ; the shaft 90 carries an arm in which is mounted a diamond 93 for dressing the outside surface 31, and the shaft 91 carries an arm 95 in which is a diamond 96 for dressing the inside surface 32. The shafts carry spur segments 98, 99 respectively engaging racks 100, 101 in the side of a piston 102, reciprocable in a cylinder 103 in the housing 75. On the end of shaft 90 is an arm 105, carrying a ball 106 acting as a follower to engage the surface 107 of a cam 108 carried by the housing, the ball being held up to the cam surface by a spring 110, and being mounted in a raceway in engagement with an inclined surface 116 in the arm 105, so that when the rotation of the shaft 90 is reversed, the ball allows axial movement of the shaft. The shaft 91 has thereon an arm 119 riding under pressure of a spring 121 against the face of a cam 120 in the housing 75 ; the cams 108, 120 control the profile shapes dressed on the wheel surfaces 31, 32 as the diamonds 93, 96 are swung, by rotation of the shafts 90, 91, across the surfaces. The bracket 50 is moved about its pivot, to move the dressers into and out of operative position, by means of a piston 125 pivotally secured by a rod 135 and pin 138 to the slide 41, and working in a cylinder 126 pivotally connected at 129 to the bracket 50, fluid being supplied or exhausted through ducts 140, 141. The tip surface 33 of the wheel is dressed by an end dresser comprising a diamond 145 carried by an arm 146 mounted on a shaft 147 journalled in a housing 152. The housing is bored to provide a cylinder 153 in which is a piston 154 having rack teeth 155 thereon in engagement with a pinion 156 on the shaft 147, whereby reciprocation of the piston swings the diamond over the tip of the wheel. The housing 152 is mounted to swivel on a slide 160 about a pin 161, the axis of which is perpendicular to the axis of shaft 147, oscillation of the housing being for two purposes, namely, to produce a flat end or tip surface on the wheel, and to move the dresser into and out of operative position. The first action is effected by a cam 170 adjustably mounted on the shaft 147 and'engaging a follower 171 on on an arm 172 cn the slide 160 ; angular adjustment of the cam determines the angle of the flat end surface of the wheel to the axis thereof. The housing is swivelled, to bring the dresser into and out of operative position, by a piston 180 in a cylinder 181 on the slide 160, the piston-rod 182 engaging, through a pivot 185, with a spring-pressed plunger 187, the spring tending to hold the dresser in operative position until moved by fluid entering the cylinder 181 by a conduit 257. The slide 160 is adjustable on a bracket 195 by means of a screw 196 to position the dresser in accordance with the wheel diameter, and the bracket 195 is adjustable perpendicularly to the slide 160 on a plate 205 ; verniers, scales and locking-bolts are provided for these adjustments. The plate 205 is mounted on the member 35 so as to be adjustable thereon around the axis of the wheel. The operation of the mechanism is controlled by a valve 220 rotatable by a hand lever 223, Fig. 18, journalled in a sleeve 221 in a bracket 222 ; the valve has grooves in its periphery which co-operate with ports in the sleeve. Pressure fluid. is supplied to the valve from ducts 250, 251 and is exhausted by ducts 252, 253, and the valve is connected to the various operating cylinders of the dresser as shown in Fig. 18 ; a shuttle valve 293 also is included. The parts are shown in position wherein the dressing mechanisms are out of operative position ; on rotation of the valve 220 to the first position, the line. 275 is put on pressure supply and the line. 255 on exhaust. This causes movement of the piston 180 to the right in cylinder 181, thus swinging the end dressing mechanism into operative position, and the piston 125 also is moved to the left to swing the side dressing mechanism into operative position. A piston 266 also is moved to the left to actuate a pawl 271 to feed the grinding- wheel to the diamonds ; the pistons 102, 154 remain at the upper ends of their cylinders. The valve 220 then is rotated to the second position, which puts line 280 on supply and line 281 on exhaust, so that the. piston 102 moves,down in cylinder 103 to swing the arms 92, 95 to rough dress, the outside, and inside surfaces of the wheel. A spring 294 in the: shuttle valve chamber 291 also moves the valve 293 upwardly, thus putting line 316 on supply and line 315 on exhaust, so that piston 154 is moved down, causing the end dresser, to swing, in one direction to rough dress the wheel tip; these rough dressing swinging movements are unthrottled and therefore take place rapidly. The valve 220 now is moved back, thus causing the piston 102 to move upwardly, the exhaust fluid being throttled by valve 314, so that the swinging of the dressers is at slow or finish dressing speed ; the piston 154 also moves upwardly, the exhaust being throttled by valve 321, so that the return swing of the end dresser is made at finish dressing speed. The valve 220 then is returned to starting position, the parts being restored to the inoperative position. By adjustment of valve 285, the side dressers are moved during rough dressing to cut grooves whose pitch is equal to that of the end dresser ; on the finish dressing. cuts, the inside dresser and the tip dresser move to cut grooves of equal pitch P1, Fig. 22, whilst the outside dresser, through the cam 108 and lost-motion device, does not contact the wheel surface, so that the outside surface is left rough with the groove of pitch P. By the use of a suitable cam 170 the end dresser produces a flat face with rounded corners, as shown in Fig. 23.