Patent GB-518923-A (GB)
Title: Improvements in and relating to grinding, specially applicable to cams for internal combustion engines
IPC: B24B19/12
Filed: 1938-08-11
Abstract: 518,923. Grinding and marking out cams etc.; chucks. MAIDSTONE & DISTRICT MOTOR SERVICES, Ltd., FRENCH, G. F., and HALLAS, H. O. Aug. 11, 1938, No. 23720. [Classes 60 and 61 (ii)] [Also in Group XXII] In a machine for grinding or marking out cams or other articles wherein the article and a pattern are assembled with each' other to rotate on a stationary axis, the pattern being sensed by means rocking in unison with coacting grinding or marking off means, one of these means is carried by a follower arm mounted on a rockable shaft and the other is carried on a transversely movable slide carried by a saddle mounted for longitudinal movement on the shaft. A blank 15, Fig. 4, from which a master cam is to be prepared is keyed on a sleeve 1 keyed on one end of a master cam shaft. The sleeve has six external keyways spaced at equal intervals corresponding to the positions of the six cams, and an internal keyway in line with one of the external keyways and by means of these latter keyways it is keyed to the shaft and to the blank. A shaft 23, Figs. 1 and 3, is carried in bearings 21 on the machine bed. A saddle 27 carrying a shaft 40 driven by a belt or a motor, and two follower arms 38 are adjustably mounted on the shaft. Pins 53 rotatably mounted in the arms are formed for attachment of a scriber. A sensing disc mounted on the shaft 40 is moved into contact with the cam on the master shaft and one of the arms 38 is. adjusted so that the scriber will mark a circle on the blank when rotated. The saddle is weighted or provided with a spring to maintain the disc in contact with the cam. The shaft is now rotated step - by - step by hand and the scriber is hand operated to mark a series of circles on the blank. The blank is then removed, shaped to a line tangential to the insides of the circles, and hardened. The cam shaft to be ground is now fitted with the sleeve 1 on which the master cam has been mounted and is placed in the machine. The sensing disc is replaced by a grinding wheel 43a of the same diameter and the correct motion of the wheel is obtained by keeping the pin 53 in contact with the master cam. When half the cams have been ground the cam shaft is reversed to enable the other half to be ground, the follower arm adjacent the loose headstock being brought into play. Cams so far referred to have been inlet cams but a second keyway on the shaft in line with an exhaust cam enables the sleeve to be adjusted on the shaft to deal with the exhaust cams. Fig. 10 shows a sleeve with a split collet 61 engaged by a ring nut 66 which may be used with shafts of different size. The tapped hole 59 is engaged by a draw rod passing through the spindle 58a. The master grinding cam 15b is secured on the sleeve by six bolts 57. Fig. 13 shows a centre for the loose headstock fitted with a ball bearing 69. A series of flanged bushes 73 which fit the bearing have different internal diameters for supporting different shafts. The master grinding cam may be frictionally mounted on the sleeve. The shaft 40 may be arranged on the same side of the cam shaft as the follower arms. The grinding wheel may be mounted on the follower arm so that the blank may be ground to the form of a master grinding cam.