Showing papers on "Electric resistance welding published in 1987"

Method and device for controlling a short circuiting type welding system

Abstract: A method and device for controlling a power supply for arc welding in a manner to reduce spatter when the power supply is employed for depositing metal from a welding wire or electrode onto a workpiece by the short circuiting transfer mode wherein a welding current causes the welding wire to alternate between a short circuit condition and an arc condition with metal transfer occurring during a short circuit condition. This method and device includes the concept of shifting the welding current to a background current value in response to a short circuit condition, holding the welding current generally at the background current level for a preselected time, then allowing the welding current to reach the normal unimpeded current level, and causing the holding step to be terminated before the selected time in response to a detected arc condition. This concept provides a predetermined low current condition immediately upon establishing a short circuit between the welding wire or electrode and the workpiece, which low current condition is retained long enough to convert what otherwise would be a spatter-laden momentary short circuit to a short circuit where metal is transferred to the workpiece. Further, the method and device detects the slope of the welding current or voltage and shifts the welding current to the low background current level when the welding current reaches its maximum value just before breakage of the metal from the wire thus reducing the spatter energy when the molten metal breaks from the wire.

Method and apparatus for measuring and controlling indentation in resistance welding

Abstract: Apparatus and accompanying methods for use therein for measuring and controlling weld indentation during resistance welding operations are disclosed. During a welding operation, the apparatus measures changes in a distance separating a reference point located on an electrode assembly and a region situated on the surface of the workpiece being welded wherein the region is not substantially indented by the electrode. Specifically, a distance measuring system first establishes the location of the surface relative to the electrode before any welding current is passed through the weld area. The indentation is repeatedly measured by detection of ultrasonic echoes from the surface of the material being welded. Such measurements are taken at frequent intervals during the current flow period during which the weld is being formed in order to determine on a continuous basis the indentation of the electrode into the surface. The welding power may be terminated when the measured indentation reaches the desired value. In order to obtain more precise control of the indentation, the rate at which indentation occurs can be measured and the welding power can be changed on a half cycle by half cycle basis to increase or decrease the indentation rate according to a desired indentation program.

Control of friction and inertia welding processes

Abstract: Known methods of controlling inertia welding and friction welding processes fail to control metal upset, and so require post machining of the welded components. The invention pre-determines the ideal rates of relative rotation, force applied and metal upset rates for a given material to be welded, enters those rates in a microprocessor memory and then connects the microprocessor to the apparatus on which the weld is to be effected. The microprocessor monitors the actual rates, compares them with the ideal rates and, should differences occur, generates signals from those differences with which to adjust operation of the apparatus.

Apparatus and method for exchanging electrode chips used for resistance welding

Abstract: An apparatus for exchanging electrode chips used for resistance welding. The apparatus includes a base to which a shaft is rotatably mounted. A power source is connected to one end of the shaft to rotate the shaft. An electrode chip-withdrawing knife tool is made of a board connected to the other end of the shaft. The knife tool is provided with recesses which are radially directed about the axis of the shaft. The recesses have their respective knife edge portions each of which is fitted into an annular groove formed between the step portion at the front end of the shank of each arm of a welding gun and the electrode chip fitted over the shank. An electrode chip supply holder in which new polished electrode chips are received is held by a guide member.

Method of resistance welding a porous body to a substrate

Abstract: A method for resistance welding a metallic porous body, comprised of a plurality of metallic components arranged in a three dimensional matrix so as to have interconnecting pores or voids formed between said components, to a metallic substrate. The porous body and substrate each define a faying surface. The porous body is impregnated with an electrically conductive material to a predetermined distance from its faying surface, thereby defining an impregnated zone and an unimpregnated zone. The faying surfaces of the substrate and porous body are brought into physical contact so that the unimpregnated zone is disposed between the impregnated zone and faying surface of the porous body. An electrical current is passed through the porous body and the substrate, across the faying surfaces thereby forming a metallurgical bond between the faying surfaces. In the preferred embodiment of the invention: the porous body and substrate are forcibly pressed together, during the step of passing said electrical current; the umimpregnated zone is densified; and a forge weld is formed between the components of the porous body at the faying surface of the porous body and the faying surface of the substate. The electrically conductive impregnating material is preferably a metal or alloy and works to increase the electrical conductance of the impregnated zone and to preserve the porosity of the porous body in the impregnated zone.

Method of and apparatus for conducting plasma welding

Abstract: A plasma welding method has successive steps including pre-heating of members to be welded, tack welding of the members for tentatively fixing these members, keyhole welding for completely welding the members to each other, and finish padding. These steps are automatically conducted by a single plasma welding apparatus operative in accordance with a programmed sequence including data concerning the optimum conditions of operation in each step in relation to the conditions such as sizes and materials of the members to be welded. The apparatus has a welding torch, a welding head on which the welding torch is mounted for rotation, a controller adapted for storing the optimum welding conditions for successive steps of the welding process in relation to the conditions of the members to be welded, a power supply system for transmitting welding current and welding speed signal to the welding head in accordance with a command provided by the controller, and a gas supply system for supplying a plasma gas at a rate determined in accordance with a command from the controller.

Roller electrodes for electric-resistance welding machine

Abstract: A roller electrode combination for use in electric-resistance welders, the electrode having relatively rotatable components separated by very small gaps, and an electrically and thermally conductive liquid is contained by the components across the gaps; the conductive liquid being a gallium dominant composite eutectic mixture where its phase change from liquid to solid begins at possibly 5-8 degrees C Special controls are provided for the coolant for the roller electrodes, including a sensor to determining its temperature and a heater to preclude its flow through the roller electrode at temperatures below where such phase change might take place The roller electrodes may be formed of alloys of copper (Cu) and/or a sintered mixture of copper (Cu) and tungsten (W) A protective coating between 00025 and 0025 millimeters thick may be plated on surfaces of the composite copper (Cu) and tungsten (W) roller electrode that come in contact with the conductive liquid The coating may be of gold and/or of the platinum family, such as rhodium (Rh) and iridium (Ir)

Electrical resistance welding guns having workpiece clamping and independent electrode biasing

Abstract: An electrical resistance welding gun includes a hydraulically or pneumatically actuated clamping device for forcing workpieces into contact with one another, and a device for preloading and maintaining loaded contact between welding electrodes located on opposite sides of the workpieces. The electrodes are preloaded by a compression spring whose force is entirely independent of the action of the hydraulically-catuated clamping device. The electrode is supplied with electrical welding power and is cooled by circulating coolant through the electrode. A piezo-electric sensor provides an indication of the electrode biasing force and of changes in this force during welding. The force signal from the sensor may be used for feedback control of weld current and length of the period during which weld current is applied. The initial electrode force is easily adjustable by changing the effective length of the spring.

Method for controlling gas metal arc welding

Abstract: The heat input and mass input in a Gas Metal Arc welding process are controlled by a method that comprises calculating appropriate values for weld speed, filler wire feed rate and an expected value for the welding current by algorithmic function means, applying such values for weld speed and filler wire feed rate to the welding process, measuring the welding current, comparing the measured current to the calculated current, using said comparison to calculate corrections for the weld speed and filler wire feed rate, and applying corrections.

Inverter-type resistance welding machine

Abstract: The present invention is directed to an inverter-type resis­tance welding machine. A PWM inverter supplies high frequency primary voltage to a transformer. A microprocessor controls the PWM inverter by proportional-integral-deviation (PID) control through a PWM control unit. The microprocessor determines a feedforward operation amount which corresponds to a desired weld­ing current value before current is supplied to the welding elec­trodes. The time period for the calculation of an integral operation amount is effectively reduced to approximately zero by employing a calculated integral operation amount from a previous sampling.

Monitoring facility for electric welding equipment, in particular as used for metal box manufacture

Abstract: The invention relates to the art field of resistance welding utilizing rollers in conjunction with a continuous copper wire electrode and effected with welding current that remains constant on average, at least within each half-period. According to the invention, the weld between members (generally tinned metal strip) can be monitored by measuring the current that flows through the circuit created by the electrode wire, this being a function of the welding resistance that registers between the welding rollers; the value of the current thus measured is compensated in respect of the inductive effects produced by the magnetic field originating from the welding current, and relayed in digital form to a microprocessor that compares it with given maximum and minimum limits within which the reading must fall for quality of the weld to be assured.

Numerically controlled resistance-welding machine and screw-nut system or analogous; its functioning mode

Abstract: The invention relates to a resistance-welding machine of the type comprising a head (1) with two welding elements (3, 4) suitable for being displaced relative to each other and for gripping the parts to be welded (2), one (3) being connected to driving means (5) which are connected to control means (6) which are suitable for controlling the relative speed of approach of the said welding elements and the force with which they grip the said parts to be welded, as a function of the cycle of passage of the electrical current or of other parameters, the said welding elements being supplied with current by means of a step- down transformer (16) or by means of condensers. The said driving means (5) are of the purely mechanical type and are entrained by an electrical motor (5) and the said control means (6) are of the numerical type.

Spot welding electrode apparatus

Abstract: A spot welding electrode valve includes a body having an upper and a lower tapered portion and containing a hollow valve which houses a spring loaded sensor having a valve portion. The spot welding electrode valve is adapted to be mounted to a standard resistance welding electrode through its upper tapered end portion and in the mounted position the valves in the body are closed so as to circulate coolant fluid through the body and the welding electrode. The lower tapered end portion is adapted to receive a welding cap or tip which when mounted actuates the sensor to open the valves in the body to allow coolant fluid to flow inside the welding cap or tip and to remove heat generated in the welding process. When the welding cap or tip is removed for replacement or repair, the sensor will automatically close the valves in the body and confine circulation of the coolant fluid inside the spot welding electrode valve and welding electrode without external release. One purpose of the spot welding electrode valve is to allow replacement of welding caps or tips, particularly with regard to multi-electrode resistance welding machines, without the need to close the main coolant flow valve of the system.

Power source controller for inverter type resistance welding machine

Abstract: PURPOSE:To prevent a small-sized and lightweight welding transformer from being damaged by detecting the magnetic saturation based on the variation of a primary current of the welding transformer to control a switching action of an inverter according to a detected signal. CONSTITUTION:In order to detect the magnetic saturation of the welding transformer 20, a current sensor 38 is provided to wiring between a primary coil of the welding transformer 20 and an output terminal of an inverter circuit 18. Then, an output signal of said current sensor 38 is supplied to a primary current detection circuit 40 which supplies an output signal SI corresponding to the primary current Ip to a magnetic saturation detection circuit 42. The magnetic saturation detection circuit 42 produces a detected signal MS indicating a magnetic saturated state of the welding transformer 20 and in response to said signal MS, a pulse width control circuit 32 controls the switching action of the inverter circuit 18 so as to regulate the pulse width of the primary current Ip when the magnetic saturation is generated.

Production of steel pipe of clad steel

Abstract: PURPOSE:To prevent the reduction in toughness of a weld zone by resistance welding by forming a dissimilar two layer strip plate in a cylindrical clad blank pipe and by diluting the dissimilar metal by performing a welding and solidification along the welding seam in which the dissimilar metal is immersed. CONSTITUTION:The clad blank pipe of cylindrical shape is formed by continuously feeding the two layer strip plate of a base metal (low alloy part) 4 and cladding metal (high alloy part) 5 and the seam edge part thereof is subjected to a resistance welding. In this case the welding seam 8 that the base metal 4 is immersed in the cladding metal 5 is formed on the weld zone. The dissimilar metal is therefore diluted by performing welding and solidification treatment 9 upto the depth of a clad interface part 14 by a TIG electrode 10, etc. along the welding seam 8. In this way the metallic property of the weld zone is improved and the clad steel pipe having the function of a clad steel and having the sound seam part 8 causing no welding defect is obtd.

A New Laser Hermetic Sealing Technique for Aluminum Package

Abstract: A new laser hermetic sealing technique which combines nickel plating with laser welding has been developed for aluminum packages. Laser welding has proved to be the most promising hermetic sealing technique for the aluminum packages. However, laser welding of the package has been difficult because of aluminum's tendency to suffer centerline cracks in the weld zone. Nickel was added in the weld zone by laser welding nickel-plated aluminum to strengthen the weld metal and prevent centerline cracks. With this aim, the optimum plating method and plating thickness were investigated. Consequently, electroless Ni-1wt%B, 5 µm in thickness was found to be best suited to the new technique, because the laser weld zone of the package exhibits a high joint strength almost equal to the tensile strength of the parent metal, and a package leakage of less than 10-9atm · cm3/s. The reliability of the hermetically sealed package was tested in accordance with MIL-STD-202F. It was confirmed that the new technique is suitable for the aluminum package for use in space, in the stratosphere and in salt-laden air.

Electric resistance welding for zinc plated steel plate

Abstract: An electric resistance welding method for welding zinc plated steel plates. The zinc plated steel plates having at least one surface covered with a plating layer composed of mainly zinc can be welded by the present invention efficiently while overlapping said plating layers, because a material for increasing the resistance between the zinc plated steel plates is employed in the present invention, and it is either spreaded, coated or bonded on the surface of said plating layers to be joined beforehand. Thus, the electric resistance of zinc plated steel plates can be performed by a lower electric current in a shorter time without deteriorating the anti-corrosion property of zinc plated steel plates, because the electric resistance between the steel plates has been increased by such a material.

Method for diffusion welding under isostatic pressure

Abstract: Structural parts, particularly of complicated shape, are diffusion welded to each other under isostatic pressure to form permanent joints. A two phase operation is involved in the joint formation. In the first phase at least one of the welding joint forming surfaces of the two parts to be joined, is provided with a material which will form a metallurgical layer in the gap between the two surfaces forming the welding joint. The metallurgical layer forming material may be applied to one or both joint forming surfaces prior to assembly of the parts or the material may be introduced into the gap between the surfaces after the parts have been assembled. In both instances it is the aim to seal the gap prior to the second phase in which a diffusion welding is performed in a hot isostatic press.

Method and device for splash-free ignition of a welding arc during partially mechanical or completely mechanical welding using a consumable electrode

Abstract: The invention relates to a method for splash-free ignition of the welding arc during mechanical or automatic welding using a consumable electrode which moves forwards at a slow speed for ignition and is placed against the workpiece, in the case of which the arc is ignited in a controlled manner by means of a regulated welding power source which can be controlled as desired, and the arc current is matched in accordance with a specific program to the electrode acceleration produced by a conventional wire feed apparatus. In this case, the welding power source can be operated during and immediately after the welding electrode is placed onto the workpiece in a current regulated manner at a low, constant setting (desired value, nominal value, required value) until a specific arc voltage is produced. The invention furthermore relates to a device for carrying out the method, which device is characterised in that it has a controller (1) in which the following functions are carried out: Delay-time compensation (dead-time compensation) (2), rate of wire acceleration (3), rate of current rise (4), pulse-arc parameter (5), nominal process voltage (6), actual voltage value (7), starting current (8), wire accumulation rate (9) and starting signal (10), by means of a regulated welding power source (current regulator; voltage regulator) (11), an electrode feed (12) and the welding torch (13) in the circumferential region of which the workpiece (14) is located.

Welding method for can stock

Abstract: PURPOSE:To perform the electric resistance welding of various stocks for can starting with a tin free steel by irradiating a laser beam on the surface of the overlapping part of the welding zone in advance prior to the welding. CONSTITUTION:The welding is performed by irradiating a laser beam in advance on the whole part or one part of a steel sheet-steel sheet contact faces, 6, 7 and steel sheet-welding electrode contact faces 5, 8 in case of the electric resistance welding of the can stock like the tin-free steel coating with an extremely thin chrome plating on the steel sheet surface. By this laser irradiation, the chrome oxide layer 1 and metallic chrome layer 2 on the surface of the welding zone are completely removed with evaporation or alloyed with the surface material and yet the produced ultrafine powder is completely removed. The electric resistance welding for various can stocks including the tin free steel which was regarded as impossible in the past can therefore be performed easily.

Multi-spot resistance-welding machine

Abstract: A multi-spot resistance-welding machine for manufacturing welded grids consisting of a group of longitudinal wires and crosswires crossing the longitudinal wires at right-angles, to enable grids to be manufactured in which the length of at least some of the crosswires is smaller than the width of the grid and in which the relative position of these shorter crosswires can be selected with respect to the group of longitudinal wires, is equipped with two crosswire feed devices (16, 40) of which at least one, but preferably both, can be displaced and fixed in an allocated guide (15, 17; 51, 52) transversely to the feed path of the group (70) of longitudinal wires and relative to a delivery device (60) transferring the crosswires from the feed devices into the welding area.

Short-circuiting arc welding process

Abstract: The method of controlling the welding operation in short-circuiting arc welding with regularly alternating arc-burning phase and short-circuiting phase, with which not only is the formation of spatter eliminated to the greatest possible extent and a sound weld obtained and the noise during welding reduced but the energy consumption is also significantly reduced, is constituted in such a way that the actual welding current and the actual welding voltage are continuously detected and the instantaneous welding power is calculated The welding current and/or the welding voltage is then reduced in a controlled manner to such an extent that the instantaneous welding power does not exceed a predetermined maximum value

Resistance welding apparatus

Abstract: A resistance welding apparatus (10) is disclosed which is particularly adapted for use in welding parts (27) into the interior surface of a metal tube (17) in a pre-determined pattern obtained by longitudinal and rotational indexing of the tube An elongated electrode arm (20) extends into the tube and has a feed track (35) attached thereto through which the metal pieces (27) to be welded are moved down the length of the electrode arm (20) The other end of the electrode arm (20) is rigidly connected to a mount (21) and is electrically insulated therefrom At the end of the feed track (35), a lever (61) aligns the lead metal piece so as to be at the same level as an end support (43), and a pusher lug (41) advances the metal piece to the end support (43) A piston (46) carried by the end support and acting against the inside wall of the tube moves the end support (43) transversely of the electrical arm to bring the piece (27) to be welded into pressure contact with the inside of the tube (17) Electrical current is then passed through the electrode arm (20) and the piece to be welded, to the tube (17), and then to a grounded contact (47), to resistance weld the metal piece to the tube (17)

Welding method which provides a weld with corrosion protection

Abstract: A welding method for metal parts includes preparing the surface areas of the parts to be welded to provide bare metal surfaces which are clean and dry, clamping said parts together, coating the bare metal surface with a liquid coating comprised of zinc dust, manganomanganic oxide fume, and organic binder, permitting the coating to dry, and welding the coated surfaces together by gas metal arc welding.

Manufacture of blade

Abstract: PURPOSE: To prevent a defect generated at welding time and to improve the performance of a product by monocrystalizing a blade, subjecting to a heat treatment after welding by dividing it and welding it by setting such welding conditions as causing no welding defect after welding in manufacturing the welding structural blade consisting of a Ni base alloy. CONSTITUTION: The core supporting hole 2 provided at the tip part of a blade is joined by sealing it in order to facilitate support and melt-through of the core of the blade of complicated cooling structure consisting of a Ni base alloy. Or after welding said blade tip part by dividing it in the state of like horizontally splitting it the cap of the blade tip is integrated by welding it to the blade. The material is of a monocrystal or similar to that and a filler rod of Fe or Ni is used and welded under inert atmosphere or vacuum to prevent the welding crack caused by a grain boundary. The split welding is thus enabled in case of welding the blade having a complicated cooling hole, the defect generated at welding time is prevented and the product performance can be improved. COPYRIGHT: (C)1989,JPO&Japio

Process and a device for finding and following a hollow weld in shielded arc welding

Abstract: The invention concerns a process and a device for seeking and following a hollow weld during a shielded arc welding, especially welding with carbon dioxide gas The welding torch is moved by a path-controlled manipulator, whereby prior to the welding the positional coordinates of one or more weld reference point of the hollow weld are found by mechanical contour probing and the actual position of the hollow weld found therefrom is saved in the path control The lengthwise guidance is then done only through the appropriately corrected path control, only the height of the welding torch above the toe of the weld being adjusted in dependence on the welding current The mechanical contour probing is done by contact sensing of the sides of the weld adjacent to the weld reference point, and the coordinates of the weld root point are computed from these data For this purpose, the welding torch can swivel in its mounting and is provided with a switching disc which lifts away upon contact with the weld sides by deflection of the welding torch and sends a switching signal

Apparatus for contacting wires with resistance welding

Abstract: A resistance welding apparatus includes a first working electrode parallel to a second contact electrode, the working electrode having a guide channel for wires or ribbons which opens at an end face so that a resistance weld of the wire to a terminal is accomplished to form wire or ribbon bridges.