Patent GB-547110-A (GB)
Title: Improvements in and relating to electric welding apparatus
IPC: B23K11/31
Filed: 1941-06-13
Abstract: 547,110. Electric welding fluid-pressure presses. BRIGGS MANUFACTURING CO. June 13, 1941, No. 7535. Convention date, Nov. 1, 1940. [Class 83(iv)] [Also in Group XXVI] In an apparatus for electric-welding aluminium alloys &c., having fluid operated means for moving an electrode into engagement with the work, a valve operated directly by the fluid pressure applied to the electrode moving means and responsive to the application of a predetermined pressure on this means is used to supply additional fluid pressure to the electrode moving means. The movable electrode 21 is secured to an arm 24 screwed into a plunger 25 which is spring-mounted in a piston 27 slidable in a lining 32 in the lower part of a cylinder 30 and having an enlarged head 37 sliding in a lining 36 in the upper part of the cylinder. The spring 44 is adjustable by a screwed cap 46 and the relative motion between the piston and plunger is limited by shoulders 40, 42. The space 81 beneath the piston is permanently open to supply of fluid pressure from the bore 49 of the handle 47. Supply to the upper end of the cylinder is controlled by a hollow valve 57 which is normally pressed forward by a spring 61 but is opened by the engagement of a trigger 53 with a plunger 59 which contacts with a partition 60 in the valve so as to connect the ports 56 and supply fluid to the passage 50, the valve being then held open by the fluid pressure passing into the valve. The plunger 59 is immediately returned by fluid pressure passing from the reduced portion 63 through a port 65 to the rear thereof. The fluid pressure first passes to the passage 50 through an adjustable metering valve 52 so as to bring the electrode 21 into contact with the work. When a predetermined pressure is reached the fluid pressure from the passage 50 operates through a passage 76 and passages 104 and 77 respectively a pair of valves 92, 66, the former for controlling the switch operating mechanism and which is opened first and the latter for controlling the supply of additional pressure to the electrodes. These valves are normally closed by springs 101, 74, which are independently adjustable by graduated nuts 103, 79. On opening the valve 66 fluid passes into the cylinder 28 through passages 67, 72 so as first to move the piston 27 relatively to the plunger 25 against the action of the spring 44, until the head 46 of the piston engages the plunger and then to apply the forging pressure. On opening the valve 92 fluid passes through passage 68, valve 92, and passages 98, 100 and adjustable metering valve 105 into a chamber 90 in which the reduced end of a spring urged switch piston 89 projects. The chamber 90 is connected by a port with a second accumulating chamber. When a predetermined pressure is reached in these chambers the piston 89 is operated to bridge contacts 88, 85 and put in the welding current. Fluid pressure also passes from passage 98 through passage 100 and adjustable metering valve 107 into accumulating chamber 106<SP>1</SP> so that when a predetermined pressure is reached the switch is opened again by pressure passing into the chamber 86 through passage 108. The fluid pressure in cylinder 28 is connected by a passage 107<SP>11</SP> through adjustable metering valve 110 with an accumulating chamber 109 connected by passages 111 with the rear of the valve 57 so as to open the valve 57 when the pressure in rear thereof exceeds that on the front and thus to exhaust the upper end of cylinder and the switch and accumulating chambers through an exhaust port. A relief valve 122 normally closed by a spring 125 is connected by a passage 123 to the end of the cylinder 28 and by a passage 126 to the passage 67 so as to effect a rapid exhaust of fluid in rear of the piston 27 through exhaust port 130 after the exhaust port in the handle is opened.