GB280659A - Improvements to welding machines - Google Patents

Abstract

280,659. Hadley, C. A., and Rose Street Foundry & Engineering Co., Ltd. Aug. 31, 1926. Welding.-In an electric butt-welding machine the movable work-holder is moved towards the fixed work-holder by liquid pressure which is controlled automatically by the movement of the work-holder so as to vary the speed of approach. The parts to be welded are thus moved slowly towards each other according to the burning away of the metal during the Hashing period, preferably .at a gradually accelerating speed, until they reach welding heat. whereupon the current is cut off and the parts then pressed quickly together to effect the weld. The slide a carrying the movable work-holder is connected to a ram 6 and through an adjustable rod 12 to a valve 9 which normally closes a port 24 connected by a pipe 8 with the end of a hydraulic cylinder 7. On operating a valve 14 by a lever 3, water passes from a valved pipe 2 through a pipe 5 into the box 4 of the control valve and passes through a duct 17 and pipe 8 into the cylinder 7 to push forward the ram. The duct contains a creep valve 18 which is normally slightly open. This valve is connected with the slide by an adjustable link 19 pivoted to an arm 20 so that during movement of the slide the valve 18 gradually opens. When the valve 9 uncovers the port 24 the slide is pushed rapidly forward to complete the weld. The angle through which the arm 20 is moved is varied by mounting the link 19 in different holes 22, 23 in the slide and arm. The face of the lever 20 mav contact with a cam face on the valve body to vary the rate of opening of the valve. The parts are returned by water passing through a small bore pipe 53 to the front of the cylinder when the valve 14 is opened to exhaust 51. In a modification, Fig. 3, the control valve consists of a creep valve 39 carried by a lever 40 connected by a link to the slide and having an internally threaded head 42' to engage a screwed boss so as to open the valve when the slide moves forward, or the boss may be provided with a face cam engaging a similar cam on the end of the head on a spring-returned lever. The main valve 33 is opened by a tappet 34 on a lever 35 connected by an adjustable rod to the slide. In a. further form. Fig. 6, the power is supplied to the inlet 59 of the control valve and passed through a by-pass 62 containing an adjustable valve 61 into the cylinder. The main valve 54<1> is fixed to a slide 55 having an eccentric 56 engaging a pivoted cam 57 attached by a rod 58 to. the electrode slide. Motion of the slide rotates the cam and allows the valve 54<1> to open. The initial position of the valve 54' may be set by adjusting the position of the eccentric by a worm wheel 64 and worm 65. The valve may also be operated by a hand lever 66. In all forms the electrodes may be loosely linked to the valve or cam so that part of the movement of the electrodes is at a uniform speed. Specification 190,734 is referred to.