GB698321A - Improvements in or relating to hydraulic control apparatus - Google Patents

Abstract

698,321. Drilling-machine details. FIELDING & PLATT, Ltd., ROWLES, R. V., and ELY, H. J. June 26,1950 [March 8, 1949], No. 6296/49. Class 83 (iii). Means for controlling the distance moved by a hydraulically-operated carriage of a drilling or other machine-tool comprises a hydraulically-operated device 1 arranged to grip a trip-rod 10, which, after a predetermined movement of the carriage, actuates mechanism controlling a valve which in turn controls the hydraulic operation of the carriage. As applied to a drilling machine in which a progressive feed, with intermittent withdrawals to clear swarf, is given to the drill carriage, a hydraulic cylinder 1 on the carriage is connected by a pipe 3 to the main cylinder driving the carriage so that, during initial feed, the spring-loaded piston 2 slides over the rod 10 until the drill begins to cut and the increased resistance builds up the pressure in the main cylinder sufficiently to cause the piston to grip the rod and carry it along with the carriage. The rod then rotates a lever 12 about its pivot 13, and tensions a spring 16 connected between the lever and the midpoint of a toggle quadrant 17 connected to the spindle 18 of the control valve. When the lever has moved sufficiently for a peg 20 on the quadrant to clear a cam surface 19 on the lever, the spring 16 turns the quadrant suddenly through 90 degrees, as limited by a stop 23, and the control valve is operated to reverse the flow in the main hydraulic circuit so that the drill carriage is withdrawn. During the return movement, the piston again slides over the rod until it contacts a fixed stop on the rod and moves the rod rearwardly to restore the toggle to its original position so that a new cycle of operations commences, the piston gripping the rod again at a point rearward of the initial gripping point. Specification 634,457 is referred to.