Patent GB-533972-A (GB)
Title: Improvements in or relating to abrading machines
IPC: B24B5/42
Filed: 1939-10-02
Abstract: 533,972. Lapping cam or crank shafts &c. NORTON CO. Oct. 2, 1939, No. 27048. Convention date, Oct. 3, 1938. [Class 60] An abrading or lapping machine, particularly for polishing the main bearings and crank pins or cams of crank or cam shafts, comprises a number of lapping arms for gripping a number of work surfaces simultaneously, and carried by a frame reciprocated into operative and inoperative positions, a headstock and footstock for supporting and rotating the work, clamping mechanism for clamping the arms to the frame, individual hydraulic motors controlled by a single normally-operated valve for actuating the footstock, frame, arms and clamping mechanism, and an interlock between the control valve and one or more of the mechanisms operated by the individual motors to control the sequence of operations. A crank shaft 24 is laid in a cradle 330 on a table 21, which carries the headstock 22 and footstock 23 and is reciprocated on anti-friction guides on the base 20 by mechanism from a belt or motordriven headstock spindle 33 as described in U.S.A. Specification 2,092,734. The footstock centre 51 is pushed forward by an hydraulic piston 59, Fig. 3, through toggles 63, 64 and a spring-pressed sleeve 67 as described in U.S.A. Specification 2,117,960. A series of lapping arms 130-136 are pivoted at 168, Fig. 2, to separate arms 165 pivoted at 167 to supports 166 secured to bars 82, 83 which are secured to a pair of spaced arms 80 operated by an hydraulic piston 86, arm 89, link 92, and toggle levers 94, 95 so as to move the lapping arms into operative or inoperative position. Eachlappingarm, e.g. 132, Fig. 2, is provided with a pair of partially cylindrical jaws 142, 143 for engaging the parts to be polished and floatingly mounted on levers 140, 141 pivoted at 144, 145 and operated through toggles 146, 147 by a stud 148, link 151 and hydraulic piston 132b. Between the jaws and the work are carried a series of strips of flexible abrasive paper or cloth which are mounted on reels 172 and pass through guides 174, 175 on the arms 80 and through rolls 176 on arms 177 secured to the jaws 143 and after wrapping round the work are secured to reels 178 provided with ratchet mechanism 181 to prevent unwinding, this mechanism being mounted on brackets 180 carried by the jaws 142. The paper is fed forwards by hand as it becomes worn. The lapping arms which engage the crank pins may be guided for swinging movement and all the arms are held against lateral movement by parallel plates 200, 201, Fig. 11, mounted on the brackets 166. In order that the arms may be transferred from operative to inoperative position and vice versa in indexed relation the arms are clamped to the plates by sliding members 215 provided with cam-shaped depressions 216 engaging cams 217, 218 on the guide plates 200. The members 215 are moved in grooves in the plates 200 by eccentrics 223 on a shaft 221 which is oscillated by an hydraulic motor 232. The motor shaft 231 is connected to the shaft 221 by a ratchet arm 233 and a lever 236 carrying a spring-pressed plunger 237. The plunger has a knob 238 so that it can be withdrawn to allow the clamping mechanism to be manually operated. The hydraulic motors are controlled by a single valve 104, Fig. 3, provided with pistons 110-113 to provide a number of valve chambers connected by pipes 115, 118 and 72, 75 respectively with the cylinders 84 and 58, by pipes 304, 305 with the cylinder 230 and by pipes 155 and 156 with the cylinders 130a-136a. Pipes 153, 154 communicating with pipes 155, 156 are mounted on the arms 80 and are connected by pipes 132d and 132f &c. with the cylinders 132a and c. A pump 99 supplies fluid from reservoir 101'to the valve by pipe 102 and exhaust is via pipes 321 and 120 and pipe 122 with pressure relief valve 131. The valve 104 is axially moved by a hand lever 107 and the collar 248 in turn engages stops 250, 260, 270, 280 and 300 at each stage so as to interlock the various hydraulic mechanisms so as to obtain a definite and pre-determined cycle. With the valve in the position shown in Fig. 3 engaging the stop 250, the parts are in position to effect a lapping operation when the headstock control lever 320 is rocked to start rotation of the work. The plunger 250 is connected through a link and bell crank 252 to a flexible cable 253 which is connected to a bell crank 254 on the clutch operating shaft 255. The clutch is disengaged by a counting mechanism and the bell crank 254 is thus rocked to withdraw the plunger 250. The valve is then moved to engage the stop plunger 260 which prevents further movement of the valve until the lapping arms are clamped. The plunger 260 is connected by link 261 with a bell crank 262 and flexible cable 263 passing round a disc 266 on shaft 221. When the lapping arms are clamped by rotation of shaft 221 plunger 260 is withdrawn. Valve 104 is then moved to engage plunger 270 so that the jaws 142, 143 are released from the work by pressure through pipes 132 f &c. Plunger 270 is thus withdrawn since the stud 148 connecting the toggles 146, 147 is connected by flexible cable 273 to bell crank 272. The valve is next moved to extreme rear position to withdraw the lapping arms and footstock so as to,allow the crank shaft to be removed. After inserting a new shaft the valve is moved back to engage plunger 280 to cause arms 80 and footstock to move forward again. The straightening of toggles 94, 95 causes plunger 280 to be withdrawn through chain 281. The valve is next moved to engage a plunger 300 and fluid through pipe 153 operates the jaws 142,143 to close them on the work. The plunger 300 is connected to bell crank 302 and cable 273 and is thus released. The valve is then moved to reach again the position shown in Fig. 3. Here the clamping motor 230 unclamps the lapping arms. Through cable 310 lever 311 is rocked and shifted out of the path of a projection 313 on the bell crank 254. Headstock control lever 320 may then be rocked to start rotation of headstock again. When clutch is disengaged at the end of the lapping operation the lever 311 is rocked to lie in the path of the end 313 of the bell crank 254 to prevent starting of headstock. when the lapping arms are clamped.