Patent GB-846021-A (GB)
Title: Improvements in or relating to machine tools and particularly sawing machines and the like
IPC: B23Q3/08
Filed: 1957-05-24
Abstract: 846,021. Sawing. NOBLE & LUND Ltd., and WALKER, L. May 20, 1958 [May 24, 1957], No. 16484/57. Class 145. A sawing machine having fluid pressure operated workpiece clamps and other elements comprises valve means controlling subsequent fluid pressure operated functions which are dependent on the proper clamping of the workpiece. The element so controlled in the arrangement shown diagrammatically in Fig. 1 are a fluid pressure operated sawtraversing cylinder 13 and similarly operated stockgrips 10, and slide 11 for advancing the work. A valve 23 prevents the tooltraversing means 13 from coming into operation until the pressure on the work clamping means 12, 12a is effective, and the stockgrips 10 and slide 11 are operated in a predetermined co-related sequence by valve means 26, 17, 36, sensitive to the pressure in the clamping means, the sequence of operation being : The cylinder 12 of the clamp 12a is charged from the hydraulic pump 16 to secure the work B and to retract the bar-grips 10a and to advance the saw-traversing carriage 14 to effect the sawing operation. The carriage 14 is then retracted to its starting position and the cylinder 11 is charged to retract the bar-slide carrier 18. The bar-grip cylinders 10 are then charged to grip the bar and the work clamp 12a is released by diverting pressure to the opposite side of the clamping piston. The cylinder 11 is again charged to move the slide forward to bring the bar-stock into position for the next cut and simultaneously the valve 17 is operated through a connecting rod 46 by the slide 18 to repeat the cycle automatically until the stock has been exhausted. For semi-automatic operation the stem of the valve 36 may be adjusted so that it is incapable of operation by the saw carriage 14, and the bar-grips may be slackened off manually to clear the bar. The valve 23 opens only when the correct clamping pressure is built up in the cylinder 12 ; pressure is then supplied to the feed end of the saw traversing carriage cylinder 13 via ports 29, and 30. At the end of its forward movement the carriage operates the spool-valve 26 by engaging the stem 27, putting the port 32 into communication with the port 29 so that pressure oil is supplied to the return end of the carriage cylinder 13, and the port 30 is opened to return the exhaust oil to the oil tank 15, thus ending the automatic sequence. The spool valve 17 is then moved to the right by a manually operated member 48, e.g. a rack-and-pinion, to admit pressure to the unclamping end of the cylinder 12 to release the work, simultaneously putting pressure on the spool valve 26 to move it to the right ready for the next cutting operation. The machine may be used non-automatically by employing only one part of the spool valve 26, incorporating ports 29, 30, 32, 33, a handle 49 being provided for moving this valve as necessary. When required for manual operation the spool valve may be made in two parts ; if the machine is subsequently required for automatic or semi-automatic working the stems of the two spool-valves may be coupled. All the valves may be incorporated in a single block with suitable connections, the front of the block carrying the operating handles for the throttle valve 31 and control valves 17 and 26. Figs. 2 and 3 show a modification of the control valve 36 in which a pivoted stop 50 is interposed between it and the carriage when it is required to introduce semi-automatic working. In the position shown in full lines in Fig. 3 the carriage 14 is stopped before it can operate the valve 36 ; when in the chain dotted position the machine operates fully automatically. Alternatively, an overriding control may be fitted to the pressure regulating valve 38, Fig. 5, which shows the valve in the fully automatic position; by screwing inwards the knob 51, the rod 57 positively closes the valve 38a to close communication between the ports 19 and 37. Screwing the knob outwards allows the valve to be spring-operated for semiautomatic working.