Patent GB-1330306-A (GB)
Title: Methods of and apparatus for forming continuous bonds between  metallic members
IPC: B23K11/06
Filed: 1970-09-11
Abstract: 1330306 Welding by pressure INTERNATIONAL HARVESTER CO 11 Sept 1970 43581/70 Heading B3R [Also in Division G3] In joining two or more metallic members, by one or more continuous bonds, relative movement is effected between the members and a rotatable electrode of heat resistant material, e.g. Mo, W, Ta or their alloys or chromium plated steel which applies pressure locally and progressively to the members, and supplies current to pass through the members to a means supporting the members, and the current is controlled so that the temperature of either member does not reach its melting point but flows plastically. The surfaces to be joined are brought to a temperature which allows diffusion of atoms there-across and a flash of e.g. nickel or silver may be used on the surfaces. The joint structure resulting is substantially uniform and identical to that elsewhere in the members. An apparatus for bonding parts 60, 62, Fig. 3, comprises a lower roller electrode 66 and a vertically movable upper roller electrode 64 acted on by a pressure applying pneumatic motor 78. The rollers are driven by universally jointed shafts 90, 98 but may be freely rotatable and may be made of molybdenum, molybdenum alloys, tungsten, tungsten alloys, tantalum, tantalum alloy or steel preferably chromium coated. A control system 112 for regulating the current through the electrodes so that the bonding temperature is held constant or is varied in a predetermined manner includes a detector 114 for detecting temperature conditions at the bond line and for feeding back a comparison signal. A detector capable of measuring power consumed may be employed to maintain a desired power level. The apparatus is especially suitable for welding two flanges to a web to form straight or curved I beam, side members being attached to the web and having rounded edges to provide for shaping the fillets between the flanges and web. The flanges are held in position by strip members secured to the side members. Straight and curved beams may be made of titanium alloy (bonding temperature of 1850‹ F.) and a straight beam of nickel base alloy may be bonded at a temperature 2150‹ F. in argon. A tapered I beam and a double I beam are made using an apparatus with two side rolls in a plane normal to that containing the electrode rollers, one side roller being pressed by a fluid actuated motor. An I beam may be welded with this apparatus without employing the attached side members. Another bonding apparatus comprises a driven upper roller electrode and a lower table electrode on a roller conveyer and may be used to weld three titanium alloy components to form a T section member. A modified apparatus employs multiple upper electrodes 308, Fig. 6, in a single shaft or in tandem and may be used to weld a face sheet to webs. A rib stiffened panel, a tapered double web I beam and a box beam may be welded by this apparatus. In a further apparatus for bonding arcuate web I beams a rotatable segmented inner tool, 338, Fig. 7, is supported on a shaft 336 which may be driven and in making an I beam the web is confined between tool 338 and an outer tool 342 and flanges are arranged above and below the web to pass between electrodes 348, 350. The current control system may be operated by measurement of voltage drop, magnitude of current, thermoelectric potential between electrodes and workpieces, of temperature or of thermal expansion. Inspection of the bond quality can be combined with regulation of the temperature by measuring ultrasonic energy reflected from the bond line. A titanium-boron composite tape may be produced by arranging a grooved titanium foil 418, Fig. 28, between titanium foils 416, 420 with interposed boron filaments and bonded between molybdenum electrodes and such composite tapes are bonded to opposite sides of a titanium alloy strip. Rods of mild steel are arranged between two plates which are bonded together and then the rod inserts are removed by etching to provide a structure with passageways therein. The leading edge of an aircraft wing is also welded by the method of the invention.