Patent GB-311479-A (GB)
Title: Improvements in grinding or abrading machines
IPC: B24B47/06
Filed: 1928-02-21
Abstract: 311,479. Marks, E. C. R., (Greenfield Tap & Die Corporation). Feb. 21, 1928. \ Disc apparatus ; driving and feed devices.-In a, grinding or abrading machine, the table is reciprocated by fluid actuated mechanism so controlled that the speed of the table may be reduced and the amplitude of the movement increased during certain periods of operation of the machine. The table. 21 carries a rotary work support while transverse movement is imparted to the grinding wheel. Alternatively the grinding wheel may be reciprocated and the cross feed be imparted to the work. Oil is supplied by a pump 52 and passes along a pipe 50 past an automatic speed-controlling valve 54, throttlevalve 53, and main piston-valve 30 to the cylinder 25 by which the table is reciprocated. The valve 53 is set by a handle 60 to adjust the normal speed of operation of the table. The main valve is further controlled by auxiliary valves 33, 34, the valve 34 being actuated by an abutment 35 secured to the table and the valve 33 by an abutment carried by a support 41 sliding on a rod 44 mounted in the valve casing C. The valve 54. Fig. 3, is provided with an annular groove 67 and is forced upwardly by a spring 70. The upper part of the valve is slotted to receive a pivoted latch 75 which coacts with a notched stud 77 in the casing. A screw 81 mounted on an arm secured to the rod 44 engages the upper end of the valve. A gear 83 on the rod 44 is engaged by a pinion 86 operated by a handle 88 to rock the shaft 44. When it is desired to reduce the speed of the table travel for wheel-trueing or finish-grinding operations the handle 88 is rocked so as to depress the screw 81 to latch the valve in its lower position. Movement of the handle 88 in the opposite direction causes a screw 90 to disengage the latch to allow the valve to rise to its fully open position. When the main valve 30 is moved to the right, Fig. 18, fluid passes from the passage 55 to the pipe 27 to traverse the table, while the pipe 26 is connected to the exhaust passage 111. At the end of the movement, the valve 34 is shifted by the dog 35, thus connecting the pipes 104, 109, and shifting the main valve to the left. Pressure fluid then passes to the pipe 26 to reverse the table movement which continues until the dog 39 shifts the valve 33 to effect another reversal. The reciprocation of the tablet thus continues until the handle 32 is moved to shift the main valve to the position shown in Fig. 18. The rocking of the rod 44, in addition to reducing the speed of travel also causes increased travel of the table for trueing the wheel and the arrest of the table after the finish grinding is completed. A guide rod 120 provided in the member 41 is slidable through a forked arm 121 on the rod 44. The member 41 carries a block 128, Fig. 8, engaged by a dog 130 on the table which also carries a second dog 140. In normal operation the reversal of the table at one end of its travel is effected by the dog 130 which engages the block 128 to shift the member 41 and to actuate the auxiliary valve 33. A third dog 150 secured to the table 21 coacts with a block 153 on a member 155 which is slidable and rotatable on the rod 44 and which carries a flange 160 engaging a screw on the main valve arm 32. The member 155 is positioned angularly by a notched flange secured to the gear 83. After the rough grinding is completed and it is desired to give the table an increased travel to bring the wheel-trueing device into operation, the member 41 is rocked by the handle 88 so that the dog 130 moves past the abutment 128 and the travel continues until the dog 140 engages the abutment to cause the reversal. At the same time the speed of the table is reduced. When the trueing is completed the handle 88 is released and is returned to its mid-position by springs and the table is then reciprocated between its normal limits but at the reduced speed until the finish grinding is completed. The operator then rocks the handle 88 in the opposite direction. This movement brings the block 153 into co-operation with the dog 150, thus sliding the member 155 until the handle 32 and main valve are brought to mid-position and the machine stopped. At the same, time the valve 54 is released and is returned to cause a normal speed of operation when the machine is re-started.