Showing papers on "Electric resistance welding published in 1979"

Method of ensuring the maintenance of constant quality of spot welds

Abstract: A method of improving the reproducibility of the welds in an electric spot welding machine comprises prior to the initiation of a welding operation passing a preheating current of lower magnitude than the welding current through the parts to be welded. When either the total electrical workpiece resistance of the parts to be welded has fallen below a given limit or when its rate of decrease is slower than a predetermined limit the changeover from preheating current to welding current is effected.

Automatic voltage compensation for digital welder control system

Abstract: An automatic voltage compensation control for a microprocessor controlled resistance welder system includes a digital voltmeter for measuring the line voltage cycle by cycle and associated circuitry to compensate the welding current in response to the measured line voltage in a manner which tends to hold the welding current constant and independent of line voltage variations. The digital voltmeter consists of a voltage-to-frequency converter coupled to a counter. The output of the voltage-to-frequency converter which is proportional to the line voltage is accumulated for the period of one cycle of the line frequency. This produces in the counter at the end of each measurement interval, a number of counts proportional to the average line voltage. The microprocessor using the count obtained adjusts the welding current by altering the timing of the firing points of the SCR contactors used to control the welding current.

Cored type welding electrode

Abstract: A cored type welding electrode which enables good penetration, has an improved range of welding voltages, produces low smoke and provides a weld deposit having good impact properties. The flux contains larger than normal quantities of basic oxides, controlled maximum amounts of acidic or amphoteric oxides and deoxidizers, and a very carefully controlled maximum and minimum amount of combined fluorine in the form of a fluoride.

Method of resistance welding

Abstract: An improved method for resistance welding two metallic articles, made of dissimilar metals which form brittle intermetallic compounds when melted together A first one of the metallic articles is provided with a tapered, flat-topped projection which is pressed against the other metallic article The first article preferably is composed of the metal most difficult to melt, as determined by the four parameters of melting point, electrical resistance, heat conductivity and specific heat The projection is formed with a predetermined relation between height, top width, and angle of taper such that a preselected extremely high welding current passed for a very short time will establish a maximum temperature near the top of the projection sufficient to melt the contacting surfaces of the two metallic articles and a temperature gradient such that an intermediate portion of the projection becomes markedly plastic while the adjacent base portion of the projection remains undeformable under extremely high welding pressure Impurities and intermetallic compounds in the molten metal at the top of the projection are squeezed out to the periphery of the surfaces to be welded, and the weld joint is made between plastic but unmelted metal of the projection and the other article

Modular microprocessor-controlled controller for resistance for resistance welding machines

Abstract: A precision resistance welding machine controller is provided which may be set to deliver welding power to each of a multiplicity of welding operations on a precisely controlled repeatable basis. The controller of the invention is modular in nature and is microprocessor controlled. The controller includes a master control module which is standard for all models, and the master control module incorporates certain control circuits including a circuit for assuring that an accurately controlled amount of power is delivered for each welding operation. This is achieved by providing precise phase angle control despite variations in line voltage, and line noise disturbances. The controller also includes a personality module which is constructed for a particular welding operation, and which is programmed to incorporate any selected number of steps to be performed in sequence by the welding machine controlled thereby in carrying out the particular welding operation. The duration of each step of the welding machine, and the amount of welding power to be delivered, is set for the particular welding operation by adjustable controls on the personality module. The master control module of the controller of the invention also includes circuitry and controls for providing a self-test capabiliity for the controller. Additional modules may also be added which include, for example, circuitry for providing active feedback of the weld, central plant monitoring, programmable capabilities, and so on.

Method and apparatus for ultrasonic welding

Abstract: Method and apparatus for ultrasonic welding of laminated material such as, for example, paper or cardboard coated with weldable plastic. The materials to be welded to one another are clamped between a sonotrode (2) as ultrasonic transducer and an anvil (1) as abutment. In this process, the ultrasonic waves act on the material at an angle (alpha) to the vertical. Owing to this oblique positioning of the ultrasonic source, in addition to the welding of the layers of material the transport of the latter through the welding device is achieved. The anvil (1) can be configured as a roll with or without drive.

Arc welding apparatus with oscillating electrode

Abstract: A welding process, such as a GMA welding process, employs a consumable electrode with the consumable electrode being oscillated back and forth over the surface of an object to which welding material is to be applied or across the gap between two pieces of metal to be welded together. At the ends of the swings of the consumable electrode an impact force is applied to the consumable electrode to interrupt its movement, thereby causing molten metal at the end of the consumable electrode from which the arc is struck to be impelled therefrom.

Power factor monitoring and control system for resistance welding with line disturbance immunity

Abstract: A power factor monitoring and control system with line disturbance immunity for controlling the quality of spot welds made by resistance welding techniques such as those used in the automotive industry on assembly line welders. As is commonly known, quality and strength of a spot weld can be correlated to a change in resistance measured through the weld as the weld progresses during the fusion progress. This change in resistance in the secondary circuit reflects back through the transformer to its primary circuit as a change in power factor. The timing changes resulting from the change in power factor are sensed by the control circuitry of this system to generate signals which are used by an 8-bit microprocessor properly programmed to operate on the signal information. By determining the amount of increase or decrease that has occurred in the current conduction angle during a group of welds, a basis for the control of the welding heat is obtained. By averaging the results of these measurements over a sufficiently large number of welds, the effect of random line disturbances is cancelled out.

Interface circuit for interconnecting an electronic controller to a resistance welding machine

Abstract: An interface circuit is provided for interconnecting an electronic controller to a contactor circuit which, in turn, controls the alternating current flow from an alternating current power source to controlled equipment, such as a resistance welding machine. The contactor circuit, for example, includes a pair of semiconductor switching devices, such as silicon controlled rectifiers (SCR)s, the two semiconductor switching devices are alternately rendered conductive during successive half-cycles of the alternating current power from the alternating current power source at times controlled by the controller for the controlled operation of the welding machine. The interface circuit includes means for monitoring the junction temperature of each of the semiconductor switching devices, and to provide an indication and a control effect should the junction temperature exceed a particular safe threshold.

Method of welding corrugated metallic materials

Abstract: In an automatic arc welding method for welding metallic materials having a vertically curved weld line, a change in the arc voltage is compared with a arc length setting voltage and the resulting difference signal is used to control the vertical position of a welding torch and hold the same at a predetermined distance from the materials to be welded, while on the other hand in response to a signal generated from an obliquity detector made integral with the torch, the torch is controlled at an angle corresponding to the oblique angle of the materials to be welded and at the same time the welding speed is controlled at a constant value in response to a signal corresponding to the torch angle.

Method for heated tool butt welding of tube and pipe of thermoplastic materials

Abstract: In a method for heated tool butt welding of pipe consisting of a thermoplastic material by placing or pressing the surfaces to be joined of the pipes to be welded into contact with a heated tool to form an inner weld bead at each end to be joined, subsequently heating the surfaces at a reduced contact pressure to the welding temperature and fitting the surfaces together under pressure after having removed the heated tool, the improvement for minimizing the formation of a protrusion within the resultant pipes which comprises pressing an elastic insert against the inner weld bead while joining said surfaces of said pipe together.

Resistance welding method

Abstract: PURPOSE: To perform sound welding without applying any special working by giving plastic deformation to a pipe through heating and pressing and performing welding, in the case of welding the pipe made of iron to a plate made of iron having a hole. CONSTITUTION: Pressing is set at the set value P 1 of the 1st stage from 0 through transient changes. At the same instant when it becomes P 1 or after a certain time limit T 1 , supply current I 1 is started. Plastic deformation is given to a pipe 1 by heating and pressing the same by this current I 1 and pressing pressure P 1 , so that a flange 16 is formed. At the same instant when the supply current I 1 ends, or after a certain time limit T 2 , the pressing force is increased and is made the set value P 2 of the 2nd stage through transient change. At the same instant when it becomes P 2 or after a certain time limit T 3 , the supply current I 2 is started. Welding is accomplished by this current I 2 and pressing force P 2 , whereby, e.g., nugget 17 is formed. Upon ending of the supply current I 2 or after a certain time limit T 4 , the pressure is removed and is dropped down to 0. COPYRIGHT: (C)1980,JPO&Japio

Method for welding girth joints in pipe lines

Abstract: A method and apparatus for welding girth joints in pipelines using two welding heads comprises the steps of moving each of the welding heads upwards around the pipeline along the respective section of the girth joint, feeding a welding wire to each of the welding heads so that the welding wire is fed substantially tangentially with respect to the surface of the pipe, and forming a circumferential weld by moulding it to hold the molten metal of the welding bath in the welding zone. An apparatus for carrying out the method for welding girth joints in pipelines comprises an annular track structure having at least two carriages mounted thereon which are connected with drives adapted to impart a translatory motion to the carriages. Each of the carriages carries a welding head provided with a welding wire feeder and a weld moulding member arranged opposite to the joint being welded. The welding wire feeder includes a guiding nozzle extending under the weld moulding member, with its axis being oriented tangentially to the surface of the pipe to feed the welding wire into the welding zone through the groove of the joint.

Method of welding utilizing both consumable and non-consumable electrodes

Abstract: A method of welding utilizing consumable and non-consumable electrodes blanketed with inert gas to weld with a minimal amount or no preheating.

Method of coupling plastic pipes by welding

Abstract: The coupling of two tubular elements is achieved by welding them together by energization of an electrical resistance element, the one element comprising a male end, the other a socket end. The coupling operation is carried out by means of a composite connecting piece comprising two rings which are fitted on one another, one acting as a support for a bifilar electrical resistance element and the other as a sheath. The electrical resistance element is thus uniformly coated in plastic material and is accurately centered, thereby ensuring uniform heating and welding. This coupling method is for use in coupling discharge pipelines for waste water and rain water and for conduits for industrial fluids.

Laser welding of steels for power plant

Abstract: Many welding applications in CEGB power plant involve components with wall thicknesses in the range 2–10 mm. Therefore, an investigation into the feasibility of laser welding types 316, 310 and DUCOL W30 steels in 6 mm thick plate has been made, the materials being typical of those used in CEGB power plant. The welds were made using the high power, transverse flow, CO2 laser based at UKAEA Culham Laboratory. The laser welding process used has been compared with TIG (tungsten inert gas), plasma and electron beam using capital cost, power requirement, ease of handling and distortion in workpieces as the criteria for comparison. Possible applications of laser welding to power plant manufacture are discussed.

Resistance welding method

Abstract: PURPOSE:To carry out the resistance welding being superior in workability not needing pressurized control parts, by making the resistance welding machine as gun type and turning on current to press the electrode rod against welding base metal by spring

Electric seam weld monitoring apparatus and method

Abstract: An improved weld monitoring apparatus and a method for its use are disclosed. Specifically, the invention relates to the application of integrating voltmeters to the monitoring of a resistance seam welding process applicable to cans and the like, wherein a blanking pulse generator is used to direct a voltage signal from the welding process to suitably adapted integrating voltmeters.

Resistance welding quality evaluating monitor

Abstract: PURPOSE: To make the sensing of the temperature of weld position and the quality evaluation from the measured temperature accurate by detecting the weld zone surface temperature of the welding works at the portion opposing to an electrode tip non-contactually, processing the electric signal thereof and automatically performing the captioned evaluation. CONSTITUTION: The electromagnetic waves radiated from the surface of the welding works 3 right above the center of the weld zone are taken out through the through-hole 18 of an upper electrode tip 2. These are led to an infrared sensor 19 through an electrode holder 1 by the optical fiber 14 mounted to the connector 15 bonded by means of a screw 16 or the like after its end face has been finished. On the way, the fiber 14 is fixed and protected by an adhesive agent 12 and covering material 13. The distance between the both end faces of the connector 15 and tip 2 is made constant so that the measurement conditions become constant. A sensor 19 detects the infrared rays in the radiation waves to detect temperature, converts this to an electric signal and supplies the same to the quality evaluating monitor. This signal is processed in the respective detection circuits for maximum voltage, maximum voltage arrival time, and voltage difference between the maximum voltage and the voltage at the end of welding, whereby the quality evaluation is automatically accomplished. COPYRIGHT: (C)1980,JPO&Japio

The Effect of Unsymmetrical Material Combination on the Contact and Switching Behavior

Abstract: Contact materials for electrical power engineering in symmetrical and unsymmetrical combination are investigated with respect to welding resistivity, contact resistance, arc motion, and arc erosion, under special consideration of Ag/C In combination with Ag/C, the welding resistivity as well as the contact resistance of W/Ag and copper are improved The arc staying time shows a distinct polarity-dependence in the region investigated (l = 350-1800 A) The erosion is also dependent on the polarity It coincides with the values that can be calculated from the anode and cathode erosions of the symmetrical combinations

Frictional pressure welding method

Abstract: PURPOSE: To reduce the power cost in comparison with the conventional method to make efficient frictional pressure welding possible, by gradually extending the molten junction part to the set size after a pair of metal bodies are brought into contact with each other partially and pressure and relative rotating movement are given to them to form a half-fused part. CONSTITUTION: In frictional pressure welding of a pair of metal bodies 1 and 2, the junction end of metal body 2 is formed into truncated cone 5, and the tip of contact part as partial contact part 6 is opposite to contact face 7 of the other metal 1 in parallel, and metal 1 is fixed, and set rotating movement in the arrow direction is given to metal 2, and pressure as shwon by the arrow is applied to metal 2. Partial contact parts of metal bodies 1 and 2 are made into a half-fused state due to frictional heat, and this half-fused part is extended gradually into full-fused junction face 4 and is finally subjected to a pressure welding junction by set pressure welding pressure in the axial direction. By this method, metals can be joined with a little input, and inputted heat per the contact face is small, so that the process can be shortened and the work efficiency can be improved. COPYRIGHT: (C)1981,JPO&Japio

Non-marring spot weld tip

Abstract: To prevent buckling and indentation of a panel being spot welded, a welding tip including an electrode of large load bearing and heat conducting surface is used to spread the load and also efficiently cool the workpiece. The large area electrode is a water cooled copper disk of large mass connected to a support arm by a coil spring. An electrical contactor on the support arm releasably engages the electrode to supply welding current thereto when welding pressure is applied to the workpiece by the welding gun. When the pressure is removed, the coil spring separates the electrode from the contactor.

Resistance welding machine

Abstract: A resistance welding machine in which a wire electrode is urged into contact with a workpiece by first and second electrode wheels, the wire having first and second surfaces extending parallel to the axis of the wire and a twisting mechanism located in the path of the wire after the first electrode and before the second electrode for twisting the wire during linear motion of the wire so that the surface of the wire presented to the workpiece at the first electrode wheel is also presented to the workpiece at the second electrode wheel

Welding bent flange onto pipe end without using filler rod - by bending out pipe end of fitting flanged auxiliary sleeve then positioning main flange with profiled rim

Abstract: The pipe end is bent outwards at 90 degrees to the axis of the pipe to form a narrow monolithic flange (a1) on the pipe; or a short length of tube with a narrow flange (a2) can be welded via a circular seam on the outside of the pipe. The main flange (b) has a bent outer rim, and a bent inner rim which tapers to a point; the inner rim blends with the fillet on flange (a1) or (a2), and its tapered end is welded to the outside dia. of the pipe or the tube. Welding is by arc welding with non-consumable electrodes; resistance welding; or induction welding. Flanges with a bent outer rim are stronger than flat flanges, so they can be reduced in thickness, thereby saving material and thus reducing their cost.

Weld monitoring apparatus and method

Abstract: An improved weld monitoring apparatus and a method for its use are disclosed. Specifically, the invention relates to the application of integrating voltmeters 10, 11, 12 to the monitoring of a resistance welding process wherein a blanking pulse generator 8 is used to direct a voltage signal from the welding process to suitably adapted integrating voltmeters 10, 11, 12.

Covering a steel pipe having a welding seam with a thermoplastic coating

Abstract: A steel pipe with a thermoplastic cover has the coverage of a welding seam reinforced by hot air heating the cover along the plastic and extruding a strip of similar plastic thereon, followed by cold water spray cooling. The pipe is centered as to the position of the welding seam vis-a-vis the heating and extruding equipment during relative longitudinal movement.

Butt double welding method of thick steel material

Abstract: PURPOSE:To perform the captioned welding at high efficiency and at low cost without doing the conventional intermediate annealing process and grinder work, by welding the root face part of the groove with lasers and then welding the face and back side by the known method CONSTITUTION:The butt parts of thick base metals A and B are machined to H- shape (or X-shape or K-shape), and the root face is processed to 1-3mm The root face parts A1 and B1 are joined butt to butt, and the groove surface is preheated, then the parts are welded with lasers After this laser welding, the back run and face run are performed by the known method Since the welding of the root face part has been finished, back droop is not caused by the back run in the groove deep part of the face side, and the subsequent gouging process is not needed, and intermediate annealing and grinder process are not necessary, so that the face run may be started immediately after the back run Thus, the welding efficiency may be greatly increased Besides, heat treatment facility is not needed, and the running cost and maintenance expenses may be saved

Oneeside plating process for longgsized metal sheet

Abstract: PURPOSE:To manufacture perfectly one-side plated metal sheets at a high plating speed in a simple and cheap manner by dipping two longsized metal sheets, in a hot dipping bath, both of the edge portions of which are continuously joined in the longitudinal direction, after which the resulting plated layers are solidified and the joined portion is continuously cut. CONSTITUTION:Flattened steel strips S1, S2 uncoiled by uncoilers C1, C2 are passed through surface purification tank 7 and correctly superposed. Both of the edge portions of the strips are then continuously welded using continuous welding machine 10 such as a high frequency resistance welding machine. Next the welded strip is fed to annealing furnace 15, annealed at 700-800 deg.C in a reducing atmosphere, cooled to around a temp. suitable for hot dipping, passed through hot dipping bath 18, sprayed with a gas from gas wiping nozzles 20 to regulate the thickness of the plated layers, and cooled in cooling duct 21. The both-side plated strip is continuously cut by side trimmer 25 along a line just inside the weld line to be separated into two strips, where are coiled by coilers 28, 28'.