Patent GB-523407-A (GB)
Title: Improvements in and relating to welding apparatus
IPC: B23K11/31
Filed: 1939-01-04
Abstract: 523,407. Welding electric switches. BRIGGS MANUFACTURING CO. Jan. 4, 1939, No. 275. Convention date, May 26, 1938. [Class 83 (iv)] [Also in Group XXXVII] An electric welding apparatus consists of a number of successively operated fluid pressureactuated welding units each with a pair of relatively movable electrodes, a fluid-operated welding switch operated each time fluid pressure is admitted to one of the units, and a valve for exhausting the switch between successive operations and movable to its exhaust position by fluid pressure, the flow of fluid to the valve being controlled so as to regulate the interval the valve is open to exhaust with respect to the interval of operation of the switch to open the circuits to the electrodes. The apparatus comprises a number of individual welders or a number of groups of welders. Each group of welders P, R in two separate banks A, B, may be connected by flexible pipes Q, S, to a separate radial port O in a plate K, each port being connected in succession to a distributing valve F comprising a hollow rotating arm G connected to a hydraulic pump N in a fluid reservoir H. If only one welder in each group is required one of the pipes Q, S may be plugged. In a ring 27 secured to the plate are cast two separate pairs of non-connecting tubes 37, 38, the tubes 37 being connected respectively at 43, 44 to a supply of compressed air. The tubes 37 each pass through a series of valve chambers 29, one registering with each port O, the tubes being slotted to supply air to the chambers. The chambers contain valves 25 or 26 pressed by springs 33 against valve seats 32 below which register slots in the tubes 38. The valves 25 co-operate with a switch D in the bank A and the valves 26 with a switch E in the bank B. When the passage M in the arm G is opposite one of the ports O, hydraulic pressure is communicated to one group of welders, the movable electrodes being thereby forced down against the action of springs. At the same time pressure in the port O raises a plunger 51 and so opens the valve 25 to bring the tubes 37, 38 into communication. Compressed air passes from the tube 38 through a port 45, Fig. 12, into a tube 53 and so through a restricted port 56 into a chamber 55 and eventually forces down the plunger 57 of the switch D against the action of a spring 58 so as to close the switch after the electrodes have engaged the work. Air at the same time passes from the tube 53 through a needle valve 65 into an accumulating chamber 62, which is also connected direct by a tube 64 to the lower end of the switch chamber. When the combined pressure of the spring 58 and air in chamber 62 exceeds the pressure in the chamber 55, the switch is opened, this taking place before the electrodes are withdrawn from the work. At this stage the arm G moves out of register with the port O which is brought into communication with the reservoir H so as to effect withdrawal of the electrodes. In order to effect a rapid exhaust of the switch operating fluid immediately the switch is opened, so as to increase the speed of welding, an exhaust valve 70 is provided which is opened during movement of the arm G. The valve is normally closed by air passing from the tube 38 through tube 78 against the action of a spring 81. The lower end of the switch chamber is connected to a sleeved accumulating chamber 82 by a pipe 83 through a needle valve 90, this chamber being also connected by a pipe 84 and ports 85 to the space below the valve 70. The chambers 55 and 62 are also connected to the valve chamber by pipes 77, 76. When the combined pressure of spring 81 and pressure from accumulating chamber 82 exceeds pressure above the valve, the latter is opened so as to exhaust the chambers 55, 62 through the port 75. The switches D, E, may be set for different time intervals so as to vary the duration of current for thick or thin work parts. Further, certain of the welders in each bank may operate with a different time interval from the rest. For this purpose a section of the tube 38 may be plugged at each end and connected to a separate switch. In another apparatus each group of welders 108, Fig. 14, may be connected to a separate control unit 102 containing a valve 103 and switch 104, the electrodes and switches both being operated by compressed air supplied through pipes 105. A circumferentially grooved valve sleeve 112 is pressed into the position shown, Fig. 16, against the action of a spring 113, by a plunger 114. The sleeve is held in this position by air passing through a restricted port 119, the air in the first instance passing through a port 118 in the plunger so as to return it to its outward position. Air passes into the welders through passage 120<SP>1</SP>, port 120 and pipe 106. At the same time air passes through a needle valve 123 into a chamber 121 so as to close the switch 124. Air also passes from the passage 120<SP>1</SP> through a needle valve 128 into an accumulating chamber 127 connected by a port with the front end of the switch chamber so as to open the switch. The chamber 127 also communicates by a needle valve 131 with a chamber 130, which communicates with the back of the valve sleeve 112 so as to return it to closed position. The passage 120<SP>1</SP> then exhausts through passage 134 and exhaust port. The plungers 114 are pushed in by solenoids 135, the circuits of which contain switches 100 operated in succession by a rotary contact disc 101. Specifications 523,444 and 523,445 are referred to. The Specification as open to inspection under Sect. 91 states that the apparatus may consist of a single welder. This subject-matter does not appear in the Specification as accepted.