Showing papers on "Spot welding published in 1994"

Device for spot welding of structures formed of pressed sheet metal elements.

Abstract: In a welding station, particularly for motor-vehicle bodies, the elements to be welded are locked in a precise position by locking devices carried by locating gates. There are provided a number of pairs of locating gates, corresponding to the number of different types of structures to be welded on which the station must operate. The gates are mounted on powered carriages which are guided longitudinally on both sides of the conveyor line to allow the pair of gates which are in the operative position to be rapidly interchanged. The elements of the structure to be welded reach the work area suspended to a hook, without being preliminarly connected to each other.

Method and woven mesh heater comprising insulated and noninsulated wire for fusion welding of plastic pieces

Abstract: A woven mesh heater generates a heat emitting surface which provides for uniform spatial distribution of heat and which is self-regulated in the preferred embodiment. The heater is particularly useful in joining together polyethylene pieces. The heater is produced from woven mesh and inserted between polyethylene pieces to be joined. Upon energization with a power source, the heater heats the polyethylene pieces to a temperature so that the pieces melt and fuse together. The heater is formed from a mesh of interleaved conductive wires and resistive wires. Electrical paths are established through the mesh by spot welding at intersection, or crossover, points of the conductive and resistive wires. The spot welding produces an electrical connection between the conductive and resistive wires at the welds. In this way, equal distance and therefore equal resistance paths are obtained. In addition, the resistive wires preferably have a two-layer laminate structure with an inner core of a high conductivity material, such as copper, and an outer surface layer of a ferromagnetic material having a particular Curie temperature. The foregoing two-layer laminate structure causes the temperature of the resistive wires to reach a peak value, provided that energization remains constant. Hence, the woven mesh heater is self-regulating.

Spot welding control method and apparatus using a servo welding gun

Abstract: A spot welding method and apparatus having electrode tips one of which is driven by a servo motor. In the method and apparatus, it is determined whether or not an abnormal condition occurs. The abnormal condition includes (a) squeezing some obstacle between the electrode tip and a workpiece, (b) a temperature adhesion of the electrode tips with the workpiece, (c) uneven pressurizing of the workpiece by the electrode tips, (d) a weld nugget dispersion, and (e) a too large electric resistance between the electrode tips and the workpiece. When such abnormal condition is detected, some counter measure is taken to prevent or decrease the abnormal condition.

Spot welding apparatus

Abstract: A spot welding apparatus comprises a welding gun having a pair of opposing welding electrodes either one of which is movable towards the other to apply a pressure onto a work and away from the other to release the pressure, a servomotor attached to the welding gun for adjusting the pressure applied to the work through movement of the movable welding electrode, a servomotor controller for controlling an operation of the servomotor, a welding current regulator for adjusting a value of welding current applied through the opposing electrodes to the work, a weld-interval timer arranged for adjusting at least one weld time interval and weld timing for the welding current and the pressure both applied to the work, and a spot welding controller electronically connected to the servomotor controller, the welding current regulator and the weld-interval timer, for simultaneously and arbitrarily adjusting a welding condition, namely the welding current, the pressure, the weld time interval and the weld timing, during a cycle of spot welding at every welding point on the work or at one specified welding point on the work.

Device for spot welding of structures constituted by sheet metal elements, particularly motor-vehicle bodies

Abstract: In a welding device for motor vehicle bodies there are provided a number of pairs of locating gates (4, 5) adapted to operate on different models of body. In the work position, each pair of locating gates (4, 5) can be selectively coupled to a plurality of auxiliary fixtures (4a, 4b, 4c; 5a, 5b, 5c) depending upon the specific version (for example hatchback, sedan, station-wagon) of the model of body to be welded.

Braided cable solidification

Abstract: A flexible current carrying cable is provided comprising a cable and an end portion of the cable being solidified wherein the end portion is compressed into a unitary member having reduced voids and enabling brazing of the end portion to a current carrying apparatus. A method of forming a current carrying cable comprises the steps of inserting an end of a cable into a spot welding machine, solidifying the end of the cable within the spot welding machine at 1100° F.-2000° F. at 10-100 psi. An alternative embodiment of the present invention includes an oxidation bump.

Dissimilar material joining method of aluminum and steel

Abstract: PURPOSE: To simply provide a joint of dissimilar materials of high strength at high cost by executing the resistance spot welding by holding the aluminum material which is one material to be welded with the steel material which is another material to be welded and a backing strip made of steel. CONSTITUTION: In a joint of dissimilar materials, the spot welded part is made of steel material 2, and the shear strength of the welded part is not only of high strength compared with the welded part of the aluminum material 1, but also no excessive moment is applied thereto because any material other than the material to be joined is not inserted in the interface to be joined of the joint. In addition, a backing strip 3 made of steel is present outside of the aluminum material 1, the joint is difficult to be deformed even when the tensile shear load is applied, and the strength of the joint becomes very high, and the base material of the aluminum material 1 is broken. The tensile shear force is not reduced even when the aluminum material of ≤0.5mm in thickness is used. COPYRIGHT: (C)1995,JPO

Spot welding equipment

Abstract: PURPOSE:To provide the spot welding equipment where stable work is performed in a short time and spatters are no scattered in the spot welding equipment which pressurizes materials to be welded from the upper and lower sides by a couple of upper and lower electrodes to perform welding. CONSTITUTION:The upper electrode 14 is provided projectingly below from an electrode holder 12, and electrode cap 18 consisting of a cylindrical insulator to cover the upper electrode 14 is fitted freely movably vertically for the electrode holder 12 and when it is in an unpressed state for the materials 30 and 32 to be welded, the electrode cap 18 is energized below by a spring 22 so that the lower end of the electrode cap 18 is protruded below from the lower end of the upper electrode 14.

Modeling primary dendrite arm spacings in resistance spot welds; Part 2: Experimental studies

Abstract: Hold time sensitivity is a potential concern when cold-rolled high-strength low-alloy sheet steels are used in resistance spot welded applications. Hold time sensitivity is defined by cracking, which occurs along the faying surface of the weld on peel testing when conventional hold times are used, and does not occur when reduces hold times are used. Hold time sensitivity is related to solidification cracking in the steel; however, it is believed that steel hardenability may also play a role. As an aid to understanding of solidification cracking in resistance spot welds, it is necessary to have an understanding of how the solidification structure develops. In this work, solidification structures in resistance spot welds have been characterized by the primary dendrite spacing. In Part 1 of this work, primary dendrite spacings were modeled by using a combination of numerical thermal modeling and closed-form primary dendrite spacings modeling. Numerical thermal modeling was used to predict solidification conditions in these welds. These solidification conditions were then used in the primary dendrite spacings model to predict the local spacings. In this paper, experimental studies were conducted to examine the validity of the modeling described in the previous paper. Experimentally, primary dendrite spacings were characterized formore » three grades of cold-rolled HSLA steel with nominal compositions of 0.05C-0.3Mn, 0.1C-1Mn and 0.15C-1.5Mn. For each steel, three separate thicknesses (nominally 0.8, 1.25 and 2.0 mm) were investigated. Primary dendrite spacings were determined at nominally the weld faying surface from deep-etched micrographs using an area-averaging technique.« less

Method and apparatus for spot welding

Abstract: A spot welding apparatus adapted particularly for joining aluminum workpieces utilizes a twisting or vibrating motion to break up oxides on the workpiece surface for improved welding and increased welding tip life. In one embodiment, a vibration inducing device is fixed to the electrode holder of a spot welding apparatus for vibrating the electrode tip during welding. In another embodiment, a camming mechanism rotates the electrode tip of the spot welding head in response to the spot welding head contacting the workpiece surface. The electrode tip rotates or twists in a limited arc after the tip contacts the workpiece to break up oxides on the workpiece surface. The electrode tip, upon removal from the workpiece surface, reverses its rotation for subsequent spot welding and to minimize the possibility of the electrode sticking to the workpiece.

Modeling primary dendrite arm spacings in resistance spot welds. I: Modeling studies

Abstract: Hold time sensitivity is a potential concern when cold-rolled high-strength low-alloy sheet steels are used in resistance spot-welded applications, hold time sensitivity is defined by cracking that occurs along the faying surface of the weld on peel testing when conventional hold times are used, and does not occur when reduced hold times are used. Hold time sensitivity is related to solidification cracking in the steel; however, it is believed that steel hardenability may also play a role. As an aid to understanding of solidification cracking in resistance spot welds, it is necessary to have an understanding of how the solidification structure develops. In this work, solidification structures in resistance spot welds have been characterized by the primary dendrite spacing

Water cooled resistance welding assembly

Abstract: A water cooled resistance welding assembly includes a tubular housing with an internal coolant system for efficiently removing heat from the inboard surface of a flat faced electrode for resistance welding either studs or nuts.

Apparatus for clamping and laser welding

Abstract: A clamping and welding apparatus for properly clamping and welding a pair of sheet materials within a welding station for both confined and accessible clamping and welding areas. When sheet materials or body panels of automobiles arrive in a welding station, the body panels typically have welding locations that are in both accessible and confined areas. In confined areas wherein the operation and maneuvering of the clamping and welding apparatus are hindered, a laser welder is connected to the end of a programmable robotic arm that provides a wide range of movement to the laser welder independent of a clamp. The clamp provides a pair of opposed clamp arms that are pivotally connected to a support member and whose pivotal movement is powered by a pair of clamp actuators units. An aperture is provided through one of the clamp arms to guide and direct the laser welder to a proper position for providing a spot weld on the body panels. When the welding location on the body panels is in an open and accessible area so that the operation and maneuvering of the clamping and welding apparatus is not hindered, the laser welder is fixedly mounted to the clamp so that the laser welder moves with the clamp arm. The laser welder is mounted outside the plane in which the clamp moves between a clamping position and unclamped position so that clogging does not occur.

Numerical treatment of the boundary conditions and source terms on a spot welding process with combining buoyancy-marangoni-driven flow

Abstract: Transient heat transfer, fluid flow, and phase change in spot welding are simulated using a continuum model of total mass, momentum, and energy. Emphasis is given to the numerical treatment of thermal and dynamic boundary conditions and the source terms of the energy equation. The present method for treating the boundary conditions not only can limit the solution domain within the internal control volumes for the overall discretization formulations but also makes it possible to model the free-surface mushy region using the same velocity modification method as in the internal mushy region. In an identical computational environment, the calculated temperature profile, velocity field, and weld pool shape are in excellent agreement with the general iteration method, but the computer speed is faster by 15-20% than that of the latter.

Metal member quality improving method by spot welding

Abstract: By applying spot welding along a crack which has occurred in an austenitic stainless steel structure without use of welding material so that spot welds are connected, melting and solidifying of the crack can be achieved, thereby to provide a metal structure which is rich with delta ferrite of the austenitic stainless steel structure or prevent propagation of the crack by enclosing it into the interior of the austenitic stainless steel structure.

Effect of weld design on the fatigue strength of laser and resistance spot welded tubular T-joints for automotive applications

Abstract: The increasing interest in laser beam welding for automotive applications has directed the attention of many researchers to investigating the durability of laser beam welded components. In this study, a comprehensive experimental study, augmented by finite element analysis, was performed to assess the effect of laser weld pattern and location on the durability of box section T-joints. Two laser beam weld configurations were assessed: straight and optimized. Additionally, for comparison purposes, fatigue of resistance spot-welded T-joints was also evaluated. Inplane bending, at an R ratio (R = min/max load) of [minus]1, was employed for all the tests. Test results showed that, on the basis of comparable weld area, laser weld configuration has a strong influence on the fatigue resistance of the T-joints. An optimized laser weld configuration was shown to provide fatigue resistance superior to a resistance spot-welded T-joint. In order to incorporate the advantages of laser beam welding, optimization of weld design should be part of the early stages of vehicle development.

Spot welding machine

Abstract: An indirect system spot welding machine in which the jig grasps a work via the material handling robot, said jig being comprised of a work clamper portion to clamp and fix the work and an earth clamper portion to connect the work to the terminal of an earth cable at a welding transformer side, the spot welding machine being provided with a lifting mechanism for supporting an electrode and another lifting mechanism for supporting a back bar, independently, to shorten the length of the earth cable to be used and eliminate the necessity of the particular jigs for the work positioning and to prevent pressed trace by the spot electrode from the products.

Defects formation mechanisms in laser welding and their suppression methods

Abstract: The significant problems of laser welding, particularly by a pulsed laser, are formation of various welding defects such as porosity, cracking and undercutting In order to reduce these defects, the authors have developed a special laser with pulse shaping function The paper describes the effects of pulse shaping on reduction of porosity and weld cracking of spot welding of difficult materials such as Al-alloys and stainless steels By the selection of optimum pulse shape the defects can be drastically reduced and the sound weld is possible to obtainThe significant problems of laser welding, particularly by a pulsed laser, are formation of various welding defects such as porosity, cracking and undercutting In order to reduce these defects, the authors have developed a special laser with pulse shaping function The paper describes the effects of pulse shaping on reduction of porosity and weld cracking of spot welding of difficult materials such as Al-alloys and stainless steels By the selection of optimum pulse shape the defects can be drastically reduced and the sound weld is possible to obtain

Resistance spot welding of metal, particularly aluminum

Abstract: A method and apparatus for resistance spot welding aluminum comprises polishing the electrode tips periodically after a number of welds. During the spot welding, a coating or dust builds up on the electrode tips and this has been generally assumed to be pure aluminum. However, it has been found that the coating or dust is aluminum oxide which is nonconductive. Consequently, when power is applied to the electrodes there is a slight spitting or explusion at the electrode tips which are in contact with the aluminum surfaces. The electrodes thus become pitted or arced out after a few welds. To overcome this problem, the electrode tips are polished intermittently after a predetermined number of welds. This can be accomplished by a polishing wheel which is moved between the electrodes when they are in an open position. The polishing wheel preferably is moved against one of the electrode tips for a short period of time and then against the other electrode tip for a similar period, after which the polishing wheel is retracted.

Spot welding electrode

Abstract: A spot welding electrode includes a shank within which cooling water is communicated, and an electrode tip. The shank is provided on the top thereof with a closed head, on which the electrode tip is dismoutably fixed.

Lap spot welding method to composite steel plate

Abstract: PURPOSE:To provide the lap spot welding method of a composite steel plate and an ordinary steel plate with which sufficient weld strength is obtainable. CONSTITUTION:A metallic plate 10 is arranged in superposition on the composite steel plate 1 and the composite steel plate 1 is superposed in the state of holding the composite steel plate 1 with the ordinary steel plate 5 and the metallic plate 10 of the same thickness as the thickness thereof and is then spot welded at the time of superposing the composite steel plate 1 interposing a resin layer 4 between a pair of skin steel plates 2 and 3 and the ordinary steel plate 5 and executing the spot welding. The current densities in both side parts with the resin layer 4 of the composite steel plate 1 in-between and the cooling conditions from electrodes 6 and 7 are equaled when these electrodes are energized between each other and, therefore, a formed D2 nugget 11 extends from the respective skin steel plates 2, 3 to a strap 10 and the ordinary steel plate 5 respectively contacting therewith. The sufficient weld strength is thus obtd.

Resistance spot welding method

Abstract: PURPOSE:To meet many kinds of production in the small scale and to reduce the cost by inserting an interposing member into the joining surface between an aluminum alloy plate and an aluminum alloy nut to perform resistance spot welding. CONSTITUTION:A ringlike insert material 13 formed by working an aluminum alloy wire having a circular cross section, for instance, is inserted into the joining surface between the aluminum alloy plate 11 and the aluminum alloy nut 12, which are pressurized, energized by a three-phase rectification type resistance welding machine and subjected to resistance spot welding. Since the contact between the insert material 13 and the aluminum alloy plate 11 side and the contact between the insert material 13 and the aluminum alloy nut 12 side are made to the contact point contacts, the contact points perform the same function as projections of projection welding and as a result, resistance spot welding with high heat generation efficiency can be realized.

Device for positioning welding gun of welding robot

Abstract: PURPOSE:To perform spot welding for the desired welding position with high accuracy by moving a robot shaft interlocking with generation of the pressurizing force for works by the welding gun. CONSTITUTION:The pressurizing force is applied to the works by both welding tips 21 and 22 by driving a servomotor 23 from the zero touch position of both welding tips 21 and 22. In this case, the correction data where the deformation quantity of a gun arm 15 caused by the pressurizing force and the contraction quantity of the respective welding tips 21 and 22 are stored in a storage medium in advance are read out, the pressurizing force of the eservomotor 23 and the displacement quantity of the gun arm 15 are added and the robot shaft and the servomotor 23 are driven. Consequently, the welding tips 21 and 22 can weld the works without displacing for the works and the welding quality can be improved without working unnecessary external force.

Welding method for weld nut

Abstract: PURPOSE:To prevent spatters generated from projections of the weld nut pressed on a base plate member from scattering and sticking to a tapped hole of the weld nut when weld nut is subjected to projection welding to the base plate member. CONSTITUTION:When the weld nut 1 provided with the projections 10 on the end face to be welded is subjected to projection welding to the base plate member 4, a vertical groove 51 is formed on the periphery of a pilot pin 5 inserted into the tapped hole 11 of the weld nut 1 from a central hole 21 of a fixed electrode 2 and a bolt hole 41 of the base plate member 4. The air is supplied around the tapped hole 11 of the end face of the weld nut 1 from this vertical groove 51 and the spatters generated from the projections 10 at the time of welding are scattered outside weld nut 1.

Method and device for determining the temperature at a spot-welded joint and a method for assessing the quality of a spot-welded joint

Abstract: The temperature is determined at a spot weld. The spot weld is between parts to be welded to one another. The parts are formed of a first metal and the spot weld is made with an electrode of a second metal placed in contact with the parts. The thermoelectric voltage between parts and the electrode is measured and the temperature is determined from the thermoelectric voltage measured in the measuring step. A device for determining the temperature includes a voltmeter connected between the parts to be welded and the electrode. The temperture determination is utilized in assessing the quality of spot-welded joints in automated manufacture, for example in the automobile industry.

Spot welding method of multilayered metal sheet and production of automobile door

Abstract: PURPOSE:To provide the spot welding method capable of surely obtaining the required welding strength with applying appropriate pressure force when a metal sheet piled with three sheet or more is welded by spot welding. CONSTITUTION:In the spot welding to weld a multilayered metal sheet piled with three sheets or more of metal plate, the prescribed metal sheet 14 among layered medial sheets 11-14 is connected to a ground 20, between a second and third metal sheet 12, 13 from the top layer side and/or a second and between any metal sheets 17, 18 lower than thereof, small protrusion 12a are provided. The electrode 7, which is placed on the same axis line L as the small protrusion, is abutted on the top layer metal sheet 11, while the prescribed pressure force is applied on metal sheets, electric current is caused to flow between the electrode and ground 20, each metal sheet is welded.