GB1448341A - Hydraulically operated cold welding tool - Google Patents

Abstract

1448341 Welding by pressure KELSEY-HAYES CO 18 Jan 1974 [23 Feb 1973] 02455/74 Heading B3R The subject-matter of this Specification is substantially the same as that described in Specification 1,397,108 except that the hydraulic pump 16 is now a two-stage type imparting two rates of movement, fast then slow, and two rates of force, weak then strong, to the dies. The claims relate to the tool having such a pump which displaces two different volumes of fluid at different pressures dependent on the resistance to movement of the dies. The pump comprises two bores 47 and 48 in which slide two pistons 52, 56 and 49 interconnected by an adjustable spring 59. The two cylinders afforded by the bores empty into passage 63, the larger 47, having a check valve 62 in passages 60, 61. Passages 91, 93 connect the bore 47 with reservoir 88. On application of handle 13, the interconnected pistons move together to provide a large volume of fluid to the die-operating mechanism. When the dies are forced laterally together and a high welding pressure is required spring 59 yields and piston 49 moves alone. Continued pumping of handle 13 may be required.