Patent GB-936225-A (GB)
Title: Feed mechanism for grinding machine
IPC: B24B47/20
Filed: 1960-05-26
Abstract: 936,225. Grinding. HEALD MACHINE CO. May 26, 1960 [Aug. 12, 1959], No. 18627/60. Class 60. A feed mechanism for a grinding machine comprises a shaft, a main hydraulic cylinder connected to the shaft for the rotation thereof, a drum member connected to the shaft for the rotation thereof, a friction band lying adjacent the drum member, a compensation cylinder connected to the band for causing it to contact and rotate the drum member and means for adjusting the amount of rotation of the drum member. The feed mechanism comprises top plate 32, middle plate 33, main body 31, and bottom plate 34 bolted together to form a unit, this construction facilitating the machining of oil passages. Cover 35 has central circular aperture 36 in which are located (i) circular hub 37 having handle 39 and rotatable handle 41, and (ii) annular dial 38 having dress knob 42. The mechanism includes constant-or-impulse feed knob 43, start of fine feed knob 44, start of coarse feed knob 45, retraction knob 46, coarse rate knob 48, fine rate knob 49, compensation knob 51 and selector knob 52, the latter consisting of on-off handle 53 and actuating handle 54 permitting hand operation of retraction or rapid feed. Hub. 37 is secured on the forward end of shaft 55 mounted in plain bearings formed in the inner surface of tubular shaft 76 mounted by roller bearings 77, 75 in body 31. Shaft 76 has a gear 82 engaging a rack formed on the side of piston 84 vertically slidable in body 31. Rotatably mounted on the rearward end of shaft 55 is drum 85 on which is fastened internal gear ring 86 engaging planetary gears 87 rotatably mounted on pinion gear 88 adapted to be attached directly or through gearing to the feed screw for the wheelhead slide. The planetary gears mesh with a sun gear or shaft 55. Drum 85 is formed with a smooth cylindrical outer surface 89 along which is located a friction ring 91 made up of two split rings connected end-to-end to form a spiral that passes completely around the cylindrical surface almost twice. Each one of the split rings is so formed that when the slightly separated ends are brought together the friction force brought to bear against the cylindrical surface is equal around the cylinder. The width of the ring is thicker intermediate the ends than it is adjacent the ends forming the split. One end of the ring is fastened to actuating block 92 attached to piston-rod 93 of hydraulic linear actuator 94, the cylinder 172 of which has its ends connected by conduits 173, 174 to a passage in plate 33 and a passage in body 31 respectively. Rotatable handle 41 is mounted on shaft 58 extending through hub 37 and having two grooves selectively engageable by ball detent 59 seated in a recess in hub 37. On shaft 58 is a gear 61 engaged by spring-loaded detent 62 mounted in hub 37. Annular dial 38 has hub 72 bolted to the forward end of shaft 76. The hub is provided with a gear 73 engageable by a spline 74 on shaft 58. Dress knob 42 is mounted on shaft 64 and has inwardly directed hub 65 slidable in bore 66 in dial 38 and urged outwardly by a spring. Shaft 64 carries gear 67 which normally engages rack 68 mounted on the back of dial 38 but which by pressure against the spring can engage circular rack 69 mounted on cam 71 pivoted at 75 on hub 72 of dial 38. Constant-or-impulse feed knob 43 is connected to shaft 95 on which is keyed crank arm 96 connected by rod 97 to crank arm 98 keyed to rotatable body 99 of valve 101. Knobs 43, 44, 45, 46 are each spring-biased to a normal outward position in which a spline on the knob engages common rack member 102 associated with lock 47; when pressed inwardly a gear on the knob engages a rack formed on a vertically movable cam. Knob 44 has inner knob 103 mounted on stub shaft 104 mounted in bracket plate 105 attached to main body 31 by block 106 having recess 107 containing the biasing spring; when knob 44 is pressed inwardly a gear on knob 103 engages a rack on fine feed cam 108. Knob 45 has inner knob 109 mounted on stub shaft 111 whose rearward end is received in bore 112 in block 106; when knob 45 is pressed inwardly a gear on knob 109 engages a rack on coarse feed cam 113. Knob 46 has inner knob 114 having stub shaft 115 whose rearward end is received in bore 116 in block 106; when knob 46 is pressed inwardly a gear or knob 114 engages a rack on retraction cam 117. Cams 108, 113, 117 are plate-like, lie side by side in planes parallel to the front of the feed box and are engaged by tungsten carbide rodlike follower 118 mounted at the upper end of lever 119, the lower end of which is pivotally attached to follower arm 121 attached to body 31 by pivot bolt 123 and carrying cam-follower 122 urged by springs 126 against cam 71. Follower 118 is engaged by carbide dowel 127 mounted at one end of bell-crank 128 attached to bracket plate 105 by pivot-pin 129 and having its other end attached to plunger 131 protruding from main body 31. The latter has recess 132, normally closed by cover 133, within which are mounted finish microswitch 134 and dress microswitch 135 operated by cams mounted on the rear surface of feed cam 71. Coarse rate knob 48 is attached by shaft 138 to cylindrical orifice member 139 rotatably mounted in a bore in main body 31; by rotating knob 48 any one of orifice passages 141 may be connected between pressure oil chamber 142 and passage 143. Fine rate knob 49 is attached by shaft 144 to orifice member 145; by rotating knob 49 any one of orifice passages 146 may be connected between pressure oil chamber 142 and passage 147. Compensation knob 51 is mounted at the forward end of shaft 148 to which is attached cam 149 engaging one end of rocker arm 151 attached to main body 31 by pivot-pin 152, the other end of arm 151 engaging piston-rod 93 as it extends to the left from hydraulic linear actuator 94. On-off handle 53 of selector knob 52 is mounted on shaft 153 engaging rotatable valve element 154 having partial groove 155 which, by rotating handle 53, is brought to connect passage 156 to passage 157. Valve element 154 has spring-loaded ball detents 158 which engage recesses formed in cover member 159 recessed in the back of body 31. Actuating handle 54 of selector knob 52 extends outwardly from knob 161 which extends over and is fastened to tubular shaft 162 extending through block 169 into recess 163 in body 31; tubular shaft 162 surrounds and acts as a support for shaft 153 carrying on-off handle 53. On the portion of tubular shaft 162 located within recess 163 is crank arm 164 having at one end dowel pin 165 for limiting motion of the crank arm and at the other end pin 166 provided at its outer end with a ball ; the latter resides in groove 167 formed in the lower end of plunger 168 associated with a selector valve. Coil spring 263 surrounding tubular shaft 162 between block 169 and crank arm 164 has one end fastened to block 169 and the other end to shaft 162 so that when actuating handle 54 is released it will return to an intermediate neutral position. Lubricating conduits 175, 176 are associated with the friction ring 91 to ensure smooth and consistent gripping of drum member 85. Drum member 85 has a wide flange 170 engaged by friction assemblies 178, 179 comprising a bronze friction ring adjustably spring-pressed against flange 170. Behind drum member 85 is key member 186 consisting of a circular cover-plate 187 and key 188 which extends into bore 189 extending vertically through main body 31. Key 188 extends into keyway 191 in the side of piston 84. Vertical motion of piston 84 is limited by adjustable stop 226. Cheek valve 192 has ball 193 seated against hardened metal insert 194 in middle plate 33. Plunger 131, which is attached to bell-crank 128 and forms part of sequence valve 195 is slidable in sleeve 196 mounted in body 31. Coil spring 197 located between the end of sleeve 196 and disc 198 bolted to the end of the plunger tends to keep plunger 131 drawn rearwardly, causing carbide dowel 127 mounted on the end of bell-crank 128 to press tightly against cam follower 118 so that cams 108, 113, 117 are followed closely. Plunger 131 has elongated grooves 199, 201 and the sleeve 196 has grooves 202-207. In the lower part of body 31 is located valve 101 actuated by rotation of knob 43. The rotatable body 99 of the valve is retained by a circular plate 208. A transverse passage 209 at the end of body 99 is joined to an axial passage 211. Located beside valve 101 is pilot valve 213 comprising piston 214 slidable in vertical bore 215 in body 31. Input port 216 extends through bottom plate 34 and output port 217 opens at the upper end of the bore. The piston has a central bore 218; the bore 215 has grooves 219, 221. Check valve 222 has ball 223 seated against hardened metal insert 224 in middle plate 33. An orifice assembly has plug 228 with fine axial orifice held by spring 231 against hard metal insert 229 mounted in a bore in bottom plate 34. Plunger 168, forming part of selective valve 232, has grooves 233, 234, 235, and is slidable in vertical bore 236 extending entirely through body 31. The bore has grooves 237, 238, 239, 241, 242. The hydraulic circuit incorporating the above elements is shown in Fig. 23. Operation.-Knob 43 turns the valve body 99 thereby determining whether oil will be directed through the pilot valve 213 for impulse feed or will by-pass the valve for constant feed. Knobs 44, 45, 46 raise or lower the cams 108, 113, 117 to regulate the path of the camfollower 118, thereby determining when the sequence valve 195 changes from rapid advance position to coarse feed position, from coarse feed position to fine feed position and from fine feed position to retraction position. The knob 42 adjusts the position of the cam which cooperates with the dress microswitch 135, the latter operating to cause the wheel head to move on an extended traverse for contact of the abrasive wheel with the dressing diamond. The knobs 48, 49 adjus