Patent GB-380906-A (GB)
Title: Wood grinding machines
IPC: B27L11/06
Filed: 1931-08-11
Abstract: 380,906. Rasping wood. RUSSELL, A. N. and ROBB, J. D., P.O. Box 3150, Montreal, Canada. Aug. 11, 1931, No. 22736. [Class 59.] In a magazine grinder of the continuous feed type, feed members are reciprocated directly by fluid pressure so controlled that one member is moving on its return or non-working stroke whilst the remaining members feed the material forwardly by means of pawls so arranged as to slip past the wood charge on the return stroke, certain of the feed members have pawls which grip and lift the wood on the return stroke. The fluid pressure is controlled by a timing device whereby the return movement of each individual member is caused to commence at regular intervals irrespective of the position of the members. The wood 35, Fig. 1, is contained in a rectangular magazine 18 and is forced into contact with a grindstone 11 by pawls 27 pivoted in side-plates 21 connected to a piston-rod 28 movable vertically in a fluidpressure cylinder 32. The tails of the pawls rest on cross-bars 26 to which certain of the pawls may be locked when it is desired to withdraw the wood from the grindstone. The magazine is mounted on a frame 17. supported by rods 15 adjustable by worm and worm wheel. Four cylinders 32 with their associated pawls are situated on each side of the magazine and are each operated through cams 91, Fig. 6, mounted on a shaft connected by bevel wheels to shafts 80 furnished with "free-wheel" pinions 79, Fig. 1, geared to racks 76 slidable with a lost motion in one of the cross-bars 26. The cams 91 are displaced relatively to one another on the shaft such that seven of the pressure cylinders are acting downwardly whilst the eighth is making a return stroke. Each cam operates valves 98, 99, Fig. 6, in a fluid pressure compartment 94 and drain compartment 95 respectively, an upper compartment 93 being connected by a pipe 68 to the upper end of a differential piston 63, Fig. 8, connected by a piston-rod 63b to valves 38, 39 supplied with fluid at approximately 100 and 200 lbs. respectively, on a pressure cylinder 32. The valves 98, 99 are operated by a rocker 106 which makes contact with the cam 91 through a set-screw, and the valve spring 100 is made stronger than the spring 101 so that the valve 99 is maintained in the open position. The pipe 68 is open to the top of the differential piston 63 and a three-way cock 69 and branch pipe 67 connects the main 68 to a pressure main 66 at the bottom of the differential piston 63, and is used when the feed member becomes jammed to return it to the starting point by closing the main 68 and opening the pipe 67 to the upper end of the cylinder. When the valve 69 is returned to its normal position the feed member resumes its normal operating sequence as determined by the timing valve mechanism. When the timing mechanism is in the position shown in Fig. 6 for the feed stroke, the pipe 68 is open to the drain chest 93 and the differential piston is moved upwardly together with the valves 38, 39 into the position shown in Fig. 12 whereby pressure fluid from a pipe 60 is admitted to the top of the feed cylinder 32 and the bottom put to drain through valve 38. During the short interval that the cam opens the valve 98 and closes the valve 99 the pipe 68 is supplied with pressure fluid and the differential piston 63 caused to descend together with the valves 38, 39 into the position shown in Fig. 13 to make the return stroke of the feed member.