GB857208A - Press tools for producing cored pressings - Google Patents

Abstract

857,208. Forging. WILKINS & MITCHELL Ltd., and BAILEY, W. July 15, 1959 [July 16, 1958], No. 22748/58. Class 83 (4). A press tool assembly for forming a cored pressing such as a valve body comprises cooperating dies 10, 11 defining a die cavity 17, Fig. 3, which close upon a hot workpiece upon operation of the main press ram 12, and core punches 14, 18, 20 operating in the joint plane of the dies and carried by slides 33, 28 also actuated by the press ram, at least one of the punches 20 being pivoted at 26 to the slide and having arcuate movement derived from the rectilinear slide movement and co-operating cam surfaces 31 or a pivoted link, Fig. 6 (not shown). The lower die 11 is supported on a floating bolster 13 acting through rods 40 on an hydraulic, pneumatic or spring-loaded bolster 39. During descent of the upper die 10 and ram 12, a cam 30 actuates the slide 28 causing the pivoted punch 20 to move inwardly until surfaces 20 and 25 contact, thereby limiting the inner position of the punch before the dies close. A cam surface on the top die 10 cooperates with a surface 42 on the punch to lock it in its inner position. Thereafter both dies move downwardly against the resistance of bolster 39 whereby three side punches 14, 18 actuated by pivoted levers 35, act through die openings 16, 19 to pierce the workpiece and also a lower punch 22 supported on fixed bolster 24 pierces the workpiece from below.