Patent GB-998078-A (GB)
Title: Automatic crankpin grinder
IPC: B24B5/42
Filed: 1962-02-14
Abstract: 998,078. Grinding crank-shafts. LANDIS TOOL CO. Feb. 14, 1962 [March 3, 1961], No. 6600/62. Heading B3D. An automatic crank-pin grinder comprises a grinding wheel support 81, Fig. 2, slidable transversely on a base 50, a work carriage 51 which is slidable longitudinally on the base and carries chucks 62, 63, Fig. 3, for supporting the crank-shaft W, means for causing relative rotation between the crank-shaft and chucks so as to successively locate the crank pins in aligment with the centres of the chucks and to effect rotary indexing of the crank-shaft, a caliper gauge 170, Fig. 3, positioned for engagement with the crank-pin to be ground, and means associated with the gauge and arranged to become effective after grinding to size to cause the necessary movements of the grinding wheel support and work carriage and indexing movement of the crank-shaft in a predetermined sequence to enable successive crank-pins to be located in grinding position. The chucks 62, 63 are supported in crank heads 60, 61 on the carriage 51 and consist of clamp arms 64, 65 actuable by pistons 66, 67 and arranged to be locked in clamping position by latches 222, 223 settable in locking position by springs and in release position hydraulically. The clamp arms grip the end main bearings of the crankshaft with the axis of the main bearings off set from the axis of rotation of the chucks by the amount of throw of the crank-shaft and with the crank-pin to be ground in axial alignment with the chuck axis so that the crank-shaft rotates about the axis of that pin. The crankshaft is rotated by a motor 70 on the crank head 61 through gearing to the drive spindles on which the chucks are mounted. With the work carriage 51 in its left-hand position, Fig. 3, a loader 185, Fig. 2, places a crank-shaft W in position between the chucks for the grinding of the first crank-pin at the right-hand end of the shaft. The carriage is located in this position by an hydraulic plunger 101 engaging in the first of a series of notches A, B, C, D in a bar 100 on the carriage and the first crank-pin is then disposed in front of the grinding wheel 80; the other three notches B, C, D serve successively to position the carriage for the grinding of the other crank-pins assuming the shaft to be of the 4-throw type. With the loaded carriage so positioned, a work positioner 150 is swung hydraulically by a piston 156 to bring a work rest shoe 160 into engagement with the first crank-pin and rotate the shaft W so that an index plate rotatable with the shaft abuts against a plunger 251 which rotates with the chuck 62. The fingers 180 of a work locator on the positioner 150 then shifts the relevant crankpin axially to align it precisely with the grinding wheel 80. The latches 223, 234 are then actuated to lock in closed position the clamparms 64, 65 which have themselves been closed by the pistons 66, 67. The shoe 160 is then retracted by moving a piston-controlled wedge 161 so that a spring 162 may withdraw it from contact with the crank-pin and this is followed by withdrawal of the fingers 180 and energization of the motor 70 to rotate the crank-shaft for the grinding operation. The grinding wheel support 81 is then fed into the crank-pin by a feed piston 85, the crank shaft being supported by the shoe 160 which is then again set to its advanced position by the wedge 161 and the positioner 150 is held in its upper position by high fluid pressure applied to the piston 156. After a predetermined time a piston 171 advances the calliper gauge 170 disposed on the positioner 150 into contact with the crank-pin, and when the gauge signals that the work is ground to size, the feed piston 85 is caused to withdraw the grinding wheel and after a brief interval the piston 156 withdraws the positioner 150. As the grinding wheel support 81 moves back it operates to effect withdrawal of the plunger 101 from the first notch A in the work carriage and opening of the clamp arms 64, 65, which are still held by the latches 222, 223, to a sufficient extent to permit indexing of the crank-shaft. The latter operation is effected by the energization of an index brake 253 which coacts with the index plate 250 to slow down the crank-shaft and cause relative rotation between the latter and the chucks, which at this stage are rotated at slow speed by the motor 70, to bring the next crank-pin into alignment with the axis of the chucks; the degree of indexing rotation of the crank-shaft is determined by the coacting of a plunger 251 (which rotates with the chucks) with one of the abutments on the then retarded index plate 250, the plunger being hydraulically brought into operation by a valve 271, the plunger 272 of which is controlled for this purpose by one of the lobes on a cam disc 273 rotatable with the chucks. The brake 253 is then de-energized to allow the crank-shaft to resume its rotation with the chucks and a piston 90 traverses the work carriage 51 to the right until it reaches the position for the grinding of its second crank-pin, the now reactuated plunger 101 engaging the second notch B in the bar 100. The work positioner 150 is then again moved to its operative position and the cycle for the grinding of the second crankpin is carried out as for the first crank-pin. The third and fourth crank-pins are then similarly ground and at the end of the last grinding cycle the carriage 51 is moved to the left until the plunger 101 again engages the first notch A in the bar 100, and the clamp arms 64, 65 are opened. A grinding cycle on the next crankshaft cannot start until the loader 185 has been retracted.