GB698593A - Apparatus for applying low pressure advance and high pressure squeeze in the hydraulic operation of die casting dies - Google Patents

Abstract

698,593. Casting-machines. PLASCO, Ltd. Dec. 11, 1951 [July 16, 1951], No. 29035/51. Class 83 (i). An apparatus for controlling a hydraulic medium used for operating the dies of a die-casting machine comprises a cylinder for hydraulic fluid and two pistons therein, one forcing fluid out of the cylinder to bring the dies together and a supplemental piston which then acts on the fluid to cause a high pressure squeeze on the die when in closed position, both pistons being actuated by pneumatically operated means. Within a casing 10 is a hydraulic cylinder 11 communicating with the die-operating mechanism by a pipe 60. The liquid within the cylinder may be acted upon firstly by a piston 19 moved down against a spring 24 by a cam 25 and secondly by a supplemental piston 57 moved up by a pneumatic piston 55 operating in a comparatively large diameter cylinder 15. The casing 10 also includes a pneumatic cylinder 12 containing a piston 29, an upper extension of which is formed as a rack to rotate the cam 25 through a gear 28. In operation, pressure air is admitted to the base of the cylinder 12 to raise the piston 29 and so rotate the cam 25 which depresses a follower-roll 22 in the forked upper end of the piston 19. Fluid is thus forced along the pipe 60 to effect the closing of the dies. As piston 29 reaches the top of its stroke it uncovers a port (not shown) and allows air to enter the base of the cylinder 15 thus forcing the plunger 57 into the cylinder 11 to produce the final squeezing of the dies. On connecting the cylinder 12 to exhaust, pison 29 is returned by a spring 48 and pistons 19, 57 by the spring 24.