GB583910A - Improvements in or relating to work-clamping devices for electric welding machines - Google Patents

Abstract

583,910. Welding. WOODHOUSE & MITCHELL, Ltd., and FORBES, L. May 18, 1944, No. 9526. [Class-83 (iv)] The work clamping jaws of an electric welding machine are first closed on the work by manual operation, other manual means then bringing into play hydraulic clamping pressure, unclamping being effected by manual means. which first relieves the hydraulic pressure and then opens the movable jaw clear of the work. The movable jaw b is carried by a slide c operated by a rack g and pinion f on a handrotated shaft e. The shaft is screw-threaded at e<1> between collars i, i<1> and engages the threaded boss of a hand wheel h. The back of the slide carries a ram d<2> in a cylinder d<1> connected through a spring-closed valve m with a reservoir n and through a pipe p with a cylinder p<1> containing a hand-operated pump piston p<2>. In order to clamp the work, the hand wheel is rotated so as to move outwards. It first moves away from a rod j connected by a rocker k to the valve which is thus closed by its spring m<1>. When the hand wheel engages the collar i, further rotation rotates the shaft e and causes the jaw b to move down to grip the work, fluid from the reservoir being drawn into the cylinder through the valve m. The piston p2 which is spring controlled is then pushed forward by a hand-operated eccentric r to push oil from the cylinder p<1> through a non- return valve p<4> and pipe p into the cylinder d<1> to apply the hydraulic clamping pressure. On returning the eccentric, the piston p<2> is pushed back by its spring r<1> and oil is drawn into the cylinder p<1> from the reservoir through the non- return valve p<3>. In order to release the work, the hand wheel is rotated in the other direction, which first causes the rod to be pushed upward by the chamfered end h<2> of the boss so as to open the valve m and then causes' the shaft e to rotate to raise the jaw b.