Showing papers on "Spot welding published in 1973"

Disposable resistance welding electrode

Abstract: This invention relates to a new type of resistance welding composite electrode which is disposable utilizing an inexpensive metal or alloy having good electrical and thermal conductivity as a holder, and a metal or alloy also having good electrical and thermal conductivity and in addition good strength at resistance welding operating temperatures for the insert tip.

Welded interconnection printed circuit board and method of making same

Abstract: An all-welded interconnection printed circuit board and method of making it is disclosed wherein a fiberglass sheet or other dielectric film impregnated with a stage B epoxy or other polymer resin with prepunched holes is placed between two thin sheets of nickel for example, and spot welds made through the prepunched holes. The assembly is thus held together and placed in a curing press where under prescribed temperature and pressure for a prescribed time stage B epoxy resin is cured to form a laminated structure of two metal layers separated by a dielectric layer. During the curing step, the epoxy resin flows around the spot welds and seals them off from the effects of etching solutions. By using printed circuit masking and etching techniques, strip circuits are formed on each side of the board. Adjacent the spot welds, holes are punched in the dielectric layer followed by resistance spot welding a lead tab to each area of a spot weld in one side of the board. Electric components, such as resistors, capacitors, or the like, have leads of sufficient length to project through the holes from the opposite side of the board which leads are resistance spot welded to the lead tabs at their outer ends. Components are removed, if desired, by cutting the lead tabs and the component leads adjacent the outer ends. New components have leads which are then welded to outer ends of the shortened lead tabs. Where additional support is needed, a further layer of fiberglass impregnated with stage B ''''no-flow'''' or ''''low flow'''' epoxy resin is bonded to the cured dielectric/etched nickel laminate in the same manner. Before such bonding, holes are formed as by punching in the support layer at the same locations as the spot welds in the metallic sheets. After bonding, holes are punched through adjacent both bonded dielectric layers, and lead tabs are welded to the previously formed spot welds at one side of the board. Components may then be attached from the other side of the board as described. Metal-dielectric-metal assemblies, or sandwiches, already formed may be bonded together with further fiberglass layers impregnated with stage B epoxy resin to form multilayered boards. Lead tabs and components would be attached as described.

Structure for and method of mesh welding

Abstract: A plurality of cylindrical welding guns for welding wire mesh in contact with each other staggered on each side of a linear transversely extending member of the wire mesh having off-center electrodes secured thereto with welding portions engageable with the wire mesh and insulated fixed electrodes positioned beneath the welding guns and wire mesh, which welding guns and electrodes secured thereto in conjunction with said fixed electrodes are adapted to produce welds at any of 2, 3, 4 and 6 inch spacing on simultaneous actuation of all of the welding guns through a single actuating media circuit having a single intake and a single outlet manifold, with all welding guns electrodes active as either welding electrodes or to provide a return circuit for welding electrodes during welding operations at all spacings, said welding guns being constructed and arranged to permit location of all transformer structure therefor on one side of the welding guns without special clearance structure.

Development of the weld-braze joining process

Abstract: A joining process, designated weld-brazing, was developed which combines resistance spot welding and brazing. Resistance spot welding is used to position and aline the parts, as well as to establish a suitable faying-surface gap for brazing. Fabrication is then completed at elevated temperature by capillary flow of the braze alloy into the joint. The process was used successfully to fabricate Ti-6Al-4V alloy joints by using 3003 aluminum braze alloy and should be applicable to other metal-braze systems. Test results obtained on single-overlap and hat-stiffened panel specimens show that weld-brazed joints were superior in tensile shear, stress rupture, fatigue, and buckling compared with joints fabricated by conventional means. Another attractive feature of the process is that the brazed joint is hermetically sealed by the braze material, which may eliminate many of the sealing problems encountered with riveted or spot welded structures. The relative ease of fabrication associated with the weld-brazing process may make it cost effective over conventional joining techniques.

High frequency vibratory spot welding of sheet metal

Abstract: This disclosure relates to spot welding of sheet metal members by the use of high frequency vibratory energy. One of the members to be welded is provided with weld locations which are vibration isolated to inhibit propagation of vibratory energy between adjacent weld locations during the weld cycle and thereby prevent the rupture of an adjacent and previously made weld.

Spot welding apparatus for welding end conductors in cylindrical electrical machine elements

Abstract: A spot welding apparatus connects the coil end strips to commutating bars of an armature. A mixture has a rotating base supporting the armature at the end opposite the commutator. An adjustable top support locates a spot welding torch in proper alignment to the bar and with a spring loaded ground slidably engaging the same bar. The torch includes a two percent thoriated tungsten electrode having a tapered or pencilled tip terminating in a blunt or flat end. A high frequency, constant potential D.C. power supply is connected to the torch and maintains power instantly available to the electrode and ground under the control of a timer. A helium shield arc is created. A position sensor carried by the top support has a pair of conductive plungers axially aligned with and slidably engaging with the commutator bars to produce an on-off control as the plungers pass over an insulator between the bars. The sensor is connected to actuate the timer which operates the power supply to strike an arc for a predetermined time. A plurality of radially distributed spot welds are provided on each bar by a series of traverses or passes about the commutator. The ends of the coils of a wound rotor may also be similarly joined by spot welds automatically created by the method and apparatus.

Electronic protection device for spot-welding equipment

Abstract: If the contact resistance of materials being spot-welded is too high, due to surface contamination, destruction of the specimen may result because of excessive heating by the welding pulse. A device is described which measures the contact resistance electronically, and so indicates when welding conditions are suitable.

Bench tool for sheet metal bending

Abstract: A rectangular top plate, a rectangular bottom plate and a rectangular spacer plate are secured together by rivets or spot welding to produce four bending slots, the walls of which along the two sides of each slot vary in width. The tool thus has the facility of producing a short or a long flange from an edge of a piece of work with said flange having any selected one of four widths.

Study on Determination of the Optimum Welding Condition in Resistance Spot Weldng

Abstract: Up to the present not a few sutdies on calculation of temperature distribution in resistance spot weld have been reported. In these studies, however, electrical contact area between two sheets being welded was not taken into consideration. Hence, their results of numerical calculation did not coincide with their experimental data.In this study the authors derived the following formula for calculating the electric contact area under pressure by means of theory of elasticity, i.e., dc=de+ktwherein dc is diameter of contact area; de, electrode diameter; t, plate thickness; k, constant. It is to be noted that the above formula does not contain the term of electrode force. However, the constant k is dependent on electrode force, hence, the formula might be said to involve electrode force term implicitly. The validity of the formula was confirmed by the results of photoeleastic experiment.On the basis of the above finding and the experimental result that the contact area initially formed is kept practically unchanged during the entire process of welding, they derived the following formula for determining the optimum welding condititon for mild steel sheets of equal thickness, namely, s=7.63×107 (de+0.8t)4/I2wherein s is welding time (see); de, electrode diameter (cm); t, plate thickness (cm); I, welding current (A). The formula elucidates a useful relation between temperature rise in the contact zone and welding current.This formula is proved to be correct by the welding experiments with the newly designed weld specimens.

Development of forming and joining technology for TD-NiCr sheet

Abstract: Forming joining techniques and properties data were developed for thin-gage TD-NiCr sheet in the recrystallized and unrecrystallized conditions. Theoretical and actual forming limit data are presented for several gages of each type of material for five forming processes: brake forming, corrugation forming, joggling, dimpling and beading. Recrystallized sheet can be best formed at room temperature, but unrecrystallized sheet requires forming at elevated temperature. Formability is satisfactory with most processes for the longitudinal orientation but poor for the transverse orientation. Dimpling techniques require further development for both material conditions. Data on joining techniques and joint properties are presented for four joining processes: resistance seam welding (solid-state), resistance spot welding (solid-state), resistance spot welding (fusion) and brazing. Resistance seam welded (solid-state) joints with 5t overlap were stronger than parent material for both material conditions when tested in tensile-shear and stress-rupture. Brazing studies resulted in development of NASA 18 braze alloy (Ni-16Cr-15Mo-8Al-4Si) with several properties superior to baseline TD-6 braze alloy, including lower brazing temperture, reduced reaction with Td-Ni-Cr, and higher stress-rupture properties.

Method for making self-centering pulleys

Abstract: A method and apparatus for making self-centering pulleys wherein strips of half-round wire are tapered over their lengths so as to have a half-round configuration at one end and a substantially flattened configuration at the opposite end and are then spirally wrapped about a cylindrical drum and affixed thereto by spot welding. The apparatus includes a knurling and wire deforming device for effecting the tapering of the wire strips as the strips are fed onto the cylindrical drum, and a welding device for spot welding the wire strips to the drum surface as they are spirally wound thereabout.

Resistance-type spot welding machine

Abstract: Since the operative distances on conventional resistance-type spot welding machines are basically unchangeable, a constant impedance has to be used. When no large operative space is in fact required for welding, such as with articles of small dimensions, power consumption becomes unnecessarily large. The present invention permits to reduce power loss as far as possible by adjusting the depth and/or distance of the operative welding space, to provide an adequate space which depends on the dimensions of the articles to be welded, so as to be operative at minimum impedance and thus maximum power factor.

Resistance spot welding of reinforcement cages - for reinforced concr

Abstract: Resistance spot welding installation for welding rectangular reinforcement cages for reinforced concrete has corresp. gps. of inner and outer electrodes surrounding or contained, respectively, by the cage. The one group is kinematically coupled to the same drive system as the other in such a manner that counter pressure is exerted to effect a compensatory movement of the corresp. electrodes. The driving mechanism can be moved w.r.t. the support structure surrounding the cage.

Manufacturing Exercise Involved in the Redesign of the Hawker Siddeley Trident (Tri-Jet) Fuselage

Abstract: The purpose of certain design studies was to examine the application of titanium construction to replace existing aluminium alloy structure using the same design loadings, applying the same structural philosophies, and accepting the same practical constraints on geometry. Under these design conditions weight savings result from the relative specific material properties of titanium alloys and aluminium alloy, the reduction in sizes permissible in titanium and, also from the exploitation of the weldability of titanium to produce more efficient configurations. Ti 8A1, 1Mo, 1V was specified (Duplex Annealed). The relatively thin fuselage skin (0.022 in.) was expected to be sufficiently free from stress corrosion hazards under aqueous conditions. Three particular areas were chosen for evaluation, viz., the sheet/stringer/frame structure in the keel area, the upper fuselage, and a window panel area. The usual attention was given to fatigue strength, critical crack length, and residual strength. Fusion welding was used whenever practicable, i.e., for skin to stringer joints and panel butt welds, with a little electrical resistance spot welding for the frame to fuselage skin attachment. The weight savings possible with the titanium design as compared with the aluminium structure were as follows: Fuselage keel area – 26.3% Upper fuselage area – 17.6% Window panel area – 28.0% The overall weight saving on the complete fuselage section was 23.6%.

Projection welding means and fitting for use therein

Abstract: This disclosure relates to a projecting welding process wherein one of the parts to be welded has a coating layer formed of an electrically nonconductive material and wherein the removal of this coating layer at the desired point of weld is automatically accomplished in the application of a second part to the first part. The second part is provided with one or more projections each of which is slightly deformable and which has a cutting edge which is shifted relative to the first part during pressure application of the second part relative to the first part in a normal welding process to effect a localized cutting away of the coating layer and thus provide for metal-to-metal contact.