Patent GB-627331-A (GB)
Title: Grinding apparatus
IPC: B24B7/02
Filed: 1947-01-29
Abstract: 627,331. Grinding and polishing. HAMILTON, A. E. Jan. 29,1947, No. 2800. Convention date, March 19, 1946. [Class 60] [Also in Group XXXVII] In a method of grinding surfaces, the work is moved intermittently and ground during the pauses in its movement by a grinding wheel which rotates on an axis parallel to the path of the work, oscillates on an axis transverse to the rotational axis and moves on the work in directions transversely of the path of the latter. The work is mounted on connected carriages 17 traversed on rails 14 by a rack 21, Fig. 5, and a gear 23 which is driven through a reduction train from an electric motor. The grinding wheel is journalled in one end of a rocking frame 54, Fig. 6, mounted on a shaft 55 carried in a ring 49 which oscillates in a ball race in a housing 47. The other end of the frame is connected to a piston contained in a pneumatic cylinder 66 connected by a ball and socket to a slide 32 which carries a motor 35 driving a gear train terminating in a boss 39 in threaded engagement with a rod 43 secured to the bed of the machine. The grinding wheel is driven by a motor 57 adjustable on the frame 54 by means of a threaded rod and a handwheel to tension the driving belt 62. A chain 71, to limit downward movement of the grinding wheel, is supported from a sprocket 73 which allows adjustment of the effective length of the chain. The slide 32, which is mounted on ball races, supports a housing containing mechanism for oscillating the ring 49. This mechanism comprises a motor driving a gear 94, Fig. 10, on a shaft 95 having an enlarged end 96 in which is eccentrically journalled a shaft 101 carrying a gear 99. The latter meshes with a stationary internally toothed ring 98 and the shaft 101 oscillates the ring 49 through a crank 103 and a link 53. The transverse movements of the grinding wheel are synchronised with the periodic forward movements of the work carriages by a control box shown in Fig. 13. An arm 107, carried by the slide 32, projects into this box to actuate trip arms 115, 116 at each end of the stroke of the slide. These trip arms are mounted on rods 109, 110 which are secured in axial alignment with one another and have threads of opposite hand, the distance between the trip arms being adjusted by hand wheels 112, 113. The rods 109, 110 also carry cam collars 117, 119 which are displaced with the trip arms to operate switches 123, 124, 129 and 130. The switches 123, 124 control the motor 35 through a starter 125 and a rheostat 126 while the switches 129, 130 control the motor for the work carriages through a starter 131 and a rheostat 132. The position of the switches 129, 130 is adjusted by handwheels 127, 128; one of the switches being used during forward movement of the work and the other during backward movement. When the arm 107 strikes the trip arm 116, the switch 124 is closed by the collar 119 and the switch 123 released to allow it to open thereby reversing the motor 35. The switch 130 is also operated to cause the motor for the work carriages to run momentarily at a speed determined by the rheostat 132, the switch 129 being displaced to an inoperative position until the work carriages are to be intermittently traversed in the opposite direction. The stroke of the arm 107 is shown by the trip arms registering with a scale on the control box which also contains the switches controlling the motor for oscillating the ring 49 and a pump motor delivering fluid to the grinding wheel. A four-way valve 142, Fig. 12, mounted in the control box controls the admission of air to the upper and lower ends of the cylinder 66. A cam 145 adjustably secured to the rotary barrel of the valve co-operates with a pin 147 which operates a regulating valve 143 to adjust the grinding pressure. The work is held on the carriages 17 by clamping screws 78, Fig. 5, having reduced ends fitting into clamping blocks 82 which have handle extensions 84 enabling the screws to be moved into and out of engagement with the work.