Patent GB-424627-A (GB)
Title: Improvements in or relating to the uniting of steel plates or other structures for ship building or other purposes
IPC: B23K11/10
Filed: 1933-05-26
Abstract: 424,627. Electric welding. SWAN, HUNTER, & W. RICHARDSON, Ltd., Neptune Works, Walker, and McBAIN, W., 17, Goswick Avenue, High Heaton, both in Newcastle-on- Tyne. May 26, 1933, No. 15304. [Class 83 (iv)] Plates, girders, angle irons, &c., at least “" thick for ships or other metal structures are butt or lap welded by fusing adjacent parts by an electric current passed through the plates between electrodes applied with light pressure, the plates being clamped at a position outside the fusion area and not nearly or completely surrounding the electrodes, so as to hold the parts without indenting the surface thereof. The clamping pressure in lap-welding which presses the parts together into intimate contact at the weld may be applied not less than “" from the weld and maintained until the weld has set. Welds are effected at a distance of about “" from the free edge of the plates so as to prevent escape of fused metal and the width of the weld is at least equal to the thickness of the plate. In butt welding spaced apart plates the welding area extends over both edges to unite these edges together. Overlapped parts A, B are welded as aforesaid at overlapping spots a or spaced spots a<1> or a butt strap D, Fig. 5, may be welded to one or both sides of plates A, B, or to a series of separated plates A, B, A<1>, B<1>, Fig. 8. In another form, Fig. 3, spaced plates may be butt-welded together at a. The welds may also be of rectangular form, as shown at a<3>, Fig. 9. The edges of the plates may be bent slightly so as to avoid any rough edge holding the plates apart. The clamping jaws may be V-shaped as shown at E, Fig. 11, or one or two pairs of jaws F, F Fig. 12, may be arranged longitudinally or laterally. The jaws or one pair thereof may be moved over the welding area, after withdrawal of the electrodes and partial cooling of the weld, so as to apply pressure to forge the joint. The clamp jaws may also be of circular form with flat, concave, or convex ends or the end of one may be concave and that of the co-operating jaw convex. The jaws may also have rectangular ends. Stepped clamping jaws H, H<1>, Fig. 20, may be used to prevent the plates bulging at the edges, a small clearance h<5> being provided to ensure proper clamping at h<1>, and the surfaces may be chamfered at h<2> to press more heavily on the edges of the plates. The parts h may be resiliently mounted on the parts h' so as to accommodate variations in thickness of the plates. Such jaws enable the welding spots to be brought nearer to the edges of the plates and the jaws may be faced with heat resisting material. Rectangular clamping jaws J, Fig. 21, may be carried by arms K, K<1>, pivoted at L, L<1>, and operated by an hydraulic ram M. The electrodes N, N<1> are separately operated and may be connected to a source of current by conductors O, O<1>, situated between the arms K, K<1>. The electrodes are pressed against the work with sufficient pressure to ensure proper contact therewith, by hydraulic rams or they may be spring loaded, or spring loaded in one direction and hydraulically controlled in the other direction. One of the arms K, K<1> may be provided with a hand lever for opening the jaws. The electrodes have detachable ends cooled by circulation of water from inlets R<3> through tubes R and spaces R<2> to outlets R<6>. The clamping pressure may be at least four tons per square inch. In one example for lap welds in ¥" plates with rough and somewhat rusty surfaces the pressure may be 50 tons on a clamping area of about 4 square inches. The current may be 27,000 amperes at 6 or 7 volts and the time may vary upwards of 12 seconds according to the thickness or nature of the plates. According to the Provisional Specification clamping may be effected on an annular area surrounding the electrodes.