GB895413A - Method and apparatus employing vibratory energy for bonding metals and metal welds formed thereby - Google Patents

Abstract

895,413. Welding by pressure. AEROPROJECTS Inc. April 10, 1959 [June 3, 1958], No. 12247/59. Class 83 (4). [Also in Group XXXIX] In welding metal workpieces, the pieces are clamped between jaws, a force is applied to urge the jaws together and hold the pieces in firm contact and then at least one of the jaws is torsionally vibrated, whereby the peripheral portion of the face of the jaw which engages the clamped pieces oscillates circumferentially, the vibratory energy being at a sufficient level to weld the pieces together. The welding may be effected at room temperature or at a temperature below the fusion point of the parts, in a vacuum or an inert gas and the vibration frequency may be 59-300,000 preferably 5000- 40,000 cycles per sec. The clamping force need not produce external deformation of more than 10% and may produce substantially no deformation. In an embodiment, metal pieces 12, 14, Fig. 1, are clamped between a torsionally rigid anvil 18 and a cylindrical rod 16 brazed or welded in an opening 26 in a member 20 at a node of the cylinder e.g. at one quarter wavelength in torsion or an odd multiple of one quarter wavelength from the free end 22 of the cylinder. The clamping force F is provided by spring, compressed air or hydraulic means. The lower end of the cylinder has brazed thereto an annular tip 28 engaging the work and a flange 30 is provided on the cylinder at one half wavelength from the free end to which are brazed at diametrically opposite points thereon (see Fig. 2) a pair of coupler members 36, 38 of transducers 32, 34 which vibrate longitudinally at the same frequency as the cylinder. The tapered couplers may be round, square or rectangular in section and may be one half or an integral multiple of one half wavelength long. The cores of the transducers are laminated nickel or other magneto-strictive material e.g. iron-cobalt, nickel-iron or aluminium-iron alloy and a D.C. polarizing and an A.C. excitation coil are wound through a rectangular opening therein. The transducer may be piezo electric e.g. quartz crystals, electro strictive e.g. barium titanate or lead zirconate, ferro electric or electro magnetic. The transducers operate in phase to vibrate the cylinder torsionally to oscillate the tip 28 to produce a ring-shaped weld without a cast structure. The parts may be of aluminium alloy and the weld may be effected in 1¢ seconds. In a modification, the transducers are secured to the cylinder, a solid rod, at the end thereof adjacent the tip 28 which is in the form of a disc rather than an annulus but which still produces a ring weld. In a further modification, a single transducer is employed which has a tongue brazed into a slot in the cylinder located one half wavelength from the ends of the cylinder, and in another modification four transducers arranged at 90 degrees to one another are brazed &c. to a flange secured to the cylinder. More than four e.g. 5, 6, 7, 11 or 12 transducers may be secured to the cylinder. A second flange may be provided on the cylinder at another nodal point and one or more transducers may be secured thereto. In another modification, the anvil in Fig. 1 is replaced by a vibrating assembly similar to that shown above the anvil. To produce a discontinuous ring weld an annular tip 66, Fig. 8, with shallow radial notches is used. A flanged tube 74, Fig. 10, is welded to an apertured plate 76 by engaging the flange with an annular tip 28 and supporting the plate on an anvil 78 formed in pieces like a collet. The tube may have a flared end welded in a counter sunk hole in the plate by a tapered annular tip. In another embodiment, the flange 98, Fig. 13, of an aluminium transistor cap 92 is welded to the flange 96 of its gold coated " Kovar " (Registered Trade Mark) base by supporting the lower flange of the assembly on a rigid anvil 107 provided with a socket 142 and engaging the upper flange with the annular tip 118 of an apparatus similar to that shown in Fig. 1. Air ejection may be used to eject a welded unit from the cylinder. It is stated that medical and surgical items may be encapsulated and that aluminium may be welded to aluminium; nickel plated low carbon steel to gold plated iron-nickel-cobalt alloy; copper to copper and aluminium alloy to iron-cobaltvanadium alloy. It is also stated that seam welds may be formed by overlapping ring welds. Specification 895,416 is referred to.