Showing papers on "Electric resistance welding published in 1994"

Interactive laser welding at elevated temperatures of superalloy articles

Abstract: A process is provided for laser welding a superalloy article (20) by pre-heating the entire weld area and region adjacent to the weld area of the article to a ductile temperature within the range of 1400-2100 degrees F with an induction heat coil (14) and maintaining such tem-perature during welding and solidification of the weld; and welding the preheated ar-ticle using a laser (11) with a powder al-loy feed (12), with a control system which controls the laser powder feed (12) and a motion system on which the article is fix-tured, wherein the control system includes a vision system which digitizes the weld area of the article (20) providing a path for the laser to follow.

Porous coated implant and method of making same

Abstract: The method forms a thin layer of metal mesh (14) on the surface (12) of the implant (10) for the bonding with a porous surface layer (16) to prevent the formation of notches within the body of the implant (10) The layer of metal mesh (14) can be formed by a number of known methods including conventional welding processes such as arc welding, resistance welding, electron beam welding, laser beam welding, friction welding, ultrasonic welding, cladding The porous metal surface layer (16) is preferably formed from titanium wire or titanium beads in a known process The porous surface layer (16) is bonded by a known process such as diffusion bonding, sintering, welding, or cladding By bonding the porous surface layer (16) to the thin layer of metal mesh (14), notches normally formed in the body of the implant (10) are substantially eliminated Therefore, the designer of the implant (10) is not limited as to the location and amount of porous surface layer (16) to be placed on the implants (10)

Infrared sensing of full penetration state in gas tungsten arc welding

Abstract: The objective of this study is to present an applicable top-side infrared sensing technique for the prospective closed-loop control of weld penetration in gas tungsten arc welding (GTAW) A model is developed to calculate the full penetration state, which is specified by the back-side bead width, from the sensed infrared images To ensure the model validity in the prospective closed-loop control, the experiments, which generate the data for the model identification, are conducted under the experimental conditions that will be encountered during practical closed-loop control of the welding process The heat transfer condition and electrode tip angle may vary during welding or from case to case Also, the control variables which are used to adjust the weld process in order to reach the required weld penetration will also change In many cases, the current can be employed as an on-line adjustable control variable because of the implementation ease, when the welding speed and arc length are maintained at the preset values Thus, different currents, workpiece sizes, and electrode tip angles are arranged in the experiments to emulate the possible current adjustments, case to case heat transfer variations, and electrode wear The infrared characteristics of the effects of these parameters are extracted to regress the full penetration state Finally, the back-side weld width (the full penetration state) is calculated using the resultant model from the sensed infrared data

Welding gas purging apparatus and method

Abstract: An apparatus and method for purging reactive gases from the vicinity of a molten weld during the welding process, having particular application to the welding of industrial process piping systems and pipelines, especially stainless steel and other alloy pipelines. A system is disclosed for boosting purging speed and efficiency by providing a multidirectional flow of purging gas adjacent to the interior walls of the pipe sections being joined. The rate of purge gas flow is automatically adjusted in response to changing gas pressures in the vicinity of the progressing weld.

Computer-integrated multi-gun welding system

Abstract: A method and apparatus are disclosed for monitoring and controlling a multi-gun resistance welding apparatus. An embodiment of the system comprises a computer which executes a routine that allows supervision of the multi-gun welding system, a programmable logic controller which controls movement of the guns and gun delivery devices, gun sensors which measure the displacement of gun electrodes, delivery device sensors for determining a location of the gun delivery devices, fixture sensors for measuring the location of a workpiece fixture, a weld controller which applies power to the gun electrodes, and an analog-to-digital converter which converts the outputs of the sensors to digital signals readable by the computer. An embodiment of the weld routine executed by the computer spatially gauges the pre-weld fit-up of the workpieces and inhibits the application of weld power if the fit-up is not within a specified tolerance. The embodiment of the routine detects stuck gun conditions after the weld, and performs a weld analysis to diagnose various faults during the welding based upon electrode position. An embodiment of a retro-fit gun sensor is presented which utilizes an electrode positioning bracket coupled to the electrode. The position of the bracket is measured by means of a linear variable displacement transducer. Using the retro-fit gun sensor, the computer-integrated welding system can be readily incorporated into commercially-available multi-gun welding systems.

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.

Auxiliary resistance welding component of steel - for punching into aluminium sheet to be welded to steel part

Abstract: A steel auxiliary component (10), for resistance welding of an aluminium sheet (48) to and which has a welding projection (22) at its front end, the other end having a head portion (23) which after welding, overlaps the free outer side (47) of the aluminium sheet (48) and onto which a welding electrode is applied. The novelty is that (a) the shank (20) has a length such that, after passage throught the aluminium sgeet (48), its end projects beyond the sheet (48) by 2-8% of the sheet thickness; and (b) the outer edge of the shank end is in the form of a cutting edge (25) for punching out the opening in the sheet (48). Also claimed is a process for fitting the auxiliary component to the aluminium sheet. ADVANTAGE - The auxiliary component is simple to fit and seats tightly in the aluminium sheet to be welded.

Process and apparatus for welding sheet metal edges

Abstract: Sheet metal edges to be welded are preheated prior to welding. At a given welding speed, this results in a smaller temperature gradient in the material to be welded. Consequently the welding speed can be increased, or material which would otherwise provide poor weld quality can be welded at a high temperature gradient. The preheating is carried out for example by high-frequency excitation of the material to be welded.

Insulating apparatus and method for attaching an insulating pad to a support

Abstract: A method for making an insulating apparatus and an insulating apparatus made from such method having an insulating pad made up of a plurality of layers of metal foil, wherein at least two of the layers are separated from each other such that there are gas spaces between the layers, and a support for supporting at least a portion of the insulating pad and attached to the insulating pad by resistance welding, whereby the plurality of layers of metal foil are compressed around the area of the weld.

Resistance welding control method

Abstract: A resistance welding control method capable of reducing generation of spatter to the utmost during consumption of electrodes, thereby obtaining a desired nugget and assuring excellent welding quality and controlling with ease. The resistance welding control method comprises the steps of detecting a primary or secondary voltage when the welding current is supplied to the workpiece, monitoring a resistance value of the workpiece at welding operation with the lapse of time based on the primary or secondary voltage and the welding current which is detected in synchronization with the detection of the primary or secondary voltage so that an expansion tendency of electrode tip diameter is recognized and stored as first data in a computer of the resistance welding apparatus and at the same time a spatter generation condition at welding operation is learned and stored as second data in the computer, obtaining a welding current pattern based on the first and second stored data and statistically processed data stored in the computer, and controlling resistance welding by the welding current pattern so as to obtain a desired nugget while reducing generation of spatter to the utmost even in the consumption of electrodes.

Welding method for rotatable shafts

Abstract: An improved welding method is provided for repairing broken rotors. The welding method preferably employs a 2.25Cr-1.0Mo-0.3V-type filler metal, preferably deposited using a narrow groove welding technique. The broken pieces are aligned end to end. A narrow groove is formed to substantially remove the end surfaces. The groove is preheated, filled with the welding filler metal, and postheated, resulting in a strong, high temperature resistant, long lasting weld.

Advancements in welding technology for composite-to-metallic joints

Abstract: The manufacturing and sale of aerospace, transportation, and civil structures invariably require joining components of different materials and compositions. Because manufacturers are constantly being pressured for lower cost and reduced weight, multiple materials are being combined in many products. Structural joining technology for dissimilar materials is in the infancy of its development for these application areas. This paper summarizes efforts to attain suitable joint strengths with dissimilar substrates (aluminum and carbon fiber-reinforced thermoplastic composites) through advancements in resistance welding technology. These efforts are centered around incorporating an automated resistance welding unit into a potential production process

Laser appts. for welding plastics parts of medical and laboratory filters - has low reject rate and uses same laser for both cutting and welding operations

Abstract: Appts. is claimed for welding plastics parts of medical and laboratory filter elements or systems, esp. for welding the housing upper and lower parts of a sterile one-way filter holder to a filter plate which is arranged, with bypass-tight filtrate spaces, between the housing parts and which is in the form of a surface filter, bulk filter or the like. The appts. includes (a) a manipulating device (29) which places the burr-free laser cut filter plates (2) directly into the filter element or between the housing upper and lower parts (30, 31) and/or which stacks the individual filter element parts to be welded; (b) a pressing device (32) which presses the filter element parts (30, 31) together; and (c) a laser unit (1) for welding the filter parts (30, 31) made of physiologically harmless PVC, polycarbonate, polysulphone, polypropylene or polyamide, the laser (4) and/or its focussing and welding optics (6, 7) being movable by a manipulation system (32, 9, 26, 27, 28) along the joint seam to be welded or along the axis of the optics and the laser emitting a laser beam of wavelength and power density corresponding to the transparency region of the plastics to be welded. Also claimed are a process for welding the plastics filter parts without burning, welding being carried out using laser radiation with low absorption and high penetration, energy coupling into the material vol. causing melting without destruction of the plastics and a medical and laboratory filter holder, made of thermoplastics, has join seams in the form of laser weld seams in longitudinally welded plastics walls of 0.5-2 mm thickness or with a joint seam depth of up to 2mm. ADVANTAGE - The appts. is inexpensive, since the same layer is used for both the cutting and welding operations, and the process has low reject rate.

Simultaneous temperature measurements on laser welded seams with at least two pyrometers in relation to monitoring process parameters and weld quality

Abstract: In laser butt welding of metal sheets, in particular sheets of unequal thicknesses, the temperature is measured at two points behind the liquid-solid interface. From combination of the two readings obtained a series of process data can be derived whereby the welding process can be monitored.

Pipe making welding method of clad stainless steel pipe

Abstract: PURPOSE: To provide a welding method of a seam weld zone in the case of production of a clad stainless steel pipe by a method, such as UOE, from a clad steel consisting of an austenitic stainless steel having excellent corrosion resistance as a base metal on an inside surface side and a low alloy steel having excellent strength as a base metal on an outside surface side. CONSTITUTION: The seam part 3 of the clad steel is subjected to edge prepn. of a double Vee shape of which the depth of the groove 4 on the inside surface side is 80 to 130% of the thickness of a cladding metal 2, the angle is 60 to 80°, the route thickness is 3 to 5mm and the angle on the outside surface side is 60 to 80°. The groove part 5 on the outside surface side is subjected to tack welding with a welding wire for the low alloy steel; thereafter, the inside and outside surfaces are subjected to submerged arc welding with one pass. As a result, the inside surface weld zone free from the defects occurring in component dilution is obtd. COPYRIGHT: (C)1995,JPO

System for and method of controlling resistance welder

Abstract: A resistance welder controller is disclosed, which controls a resistance welder for welding workpieces clamped between two electrodes with Joule heat generated by passing a welding current between the electrodes. The controller includes a preliminary current passing device for passing preliminary current between the electrodes until the workpieces and the electrodes become intimate with one another, a regular current passing device for passing regular current between the electrodes for welding the workpieces, a current control device for controlling the welding current according to the rate of expansion of the workpieces or the rate of increase of the resistance of the workpieces, and a current passing ending device for ending the welding current at or after an instant when the rate of expansion of the workpieces or the rate of increase of the resistance of the workpieces has become substantially zero.

Method of manufacturing a coil

Abstract: A wind type coil has a core with a flange whose bottom surface has a recess, and an electrode is formed on the bottom surface of the flange and is extended to the recess. A wire is wound around a body of the core, and an end of the wire is welded to the electrode in the recess by thermocompression bonding or resistance welding. The wind type coil is armored by a resin armor, part of the electrode on the bottom surface of the flange being kept bare.

Projection resistance welding method

Abstract: Two pieces of steel strip are welded together by a method employing projection resistance welding. A portion of one strip is formed with a series of aligned projections and arranged in superimposed relation with a portion of the other strip. The superimposed portions are moved through a welding zone located between upper and lower electrodes, typically a pair of rotatable welding wheels, through which a continuous electrical current flows. As the projections move into and through the welding zone, they are heated, flattened, melted and welded to the other of the two superimposed portions. The projections may be in the form of a continuous, elongated ridge (when the steel strips are uncoated) or in the form of spaced apart dimples (when the steel strips are coated or uncoated).

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

Welding deformation reducing method for one-side strap joint welding

Abstract: This invention relates to a welding deformation reducing method for a case where steel plates to be welded are set face to face with each other, the abutted portions of the plates being tack welded, one-side strap joint welding of the tack welded portions being done thereafter. In the welding deformation reducing method according to the present invention used when one-side strap joint welding is carried out, when not less than three welding electrodes are used, when Qi is welding heat input of each electrode which is determined on the basis of amperage, voltage and speed and Li the distance between a first electrode and each electrode, and when a maximum value H of the height of a tacked bead is set to be not more than a half of the thickness of the steel plates to be welded, the welding conditions are determined so that a value of a parameter P (P = 1/H ⊤Qi/(Li + k)) becomes not higher than a predetermined level. In order to carry out tack welding using a tab plate as well, P is set not higher than a predetermined level, and the height Ht of tack welded bead of a tab plate not more than a half of the thickness of the steel plates to be welded, the welding conditions being determined so that Ptab obtained by substituting the resultant values for H has a value not less than a predetermined value.

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.

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.

Laser welding of polymers

Abstract: Deep penetration welding and cutting of metals can be carried out at high speed with relatively low laser power. The efficient coupling of the laser radiation to the metal is due to the formation of a “keyhole.” Over the years, an attempt has been made to transfer the results on metals to plastics. It will be shown here that keyhole welding of plastics is limited to the very restricted set of plastics that have a boiling point. Volume heating, a mechanism that is not applicable to metals, is restricted to plastics with a good transparency for the incident radiation and with a high optical quality. Finally, surface heating is shown to be the most common mechanism for heating plastics.

Resistance welding method of metal sheet and resistance welding equipment

Abstract: PURPOSE: To prevent breakage and running inability of electric conductive tape by detaching an electrode from an electric conductive tape about in the direction perpendicular to the surface of electric conductive tape after welding and detaching an electric conductive tape from the surface of material to be welded about in the direction perpendicular to the surface. CONSTITUTION: The prescribed energizing time and holding time to materials 30, 31 to be welded by upper/lower electrodes 1, 2 are elapsed, the lower electrode 2 is detached from a lower electric conductive tape 33 about in the vertical direction by forces of each spring 72, the electric conductive tape 33 is detached from a lower material 31 to be welded about in the vertical direction by forces of each spring 82. Also, an upper electric conductive tape 32 is detached from a upper material 30 to be welded about in the vertical direction by elevation of each tape guide and the upper electrode 1, the upper electrode 1 is detached from the upper electric conductive tape 32 about in the vertical direction by forces of each spring 62.

Method of controlling the force on a resistance welding terminal or the like; and resistance welding machine making use of this method

Abstract: Method of controlling the force of a resistance welding terminal or machine which is equipped with a numerically controlled electric motor or the like. This method is characterised in that an inherent elasticity characteristic of the frame of the machine is established by allowing the motor M to exert two different forces F1, F2 on the workpieces and plotting its corresponding angles of rotation THETA 1, THETA 2, by means of which a clear relationship is established between each desired force F during a certain phase of the relevant process and the corresponding angle of rotation THETA which is to be performed by the motor M, as a result of which it is possible to vary the force during the phases "welding" and "holding after the welding". An elastic intermediate piece 14 can be inserted into the frame of the machine. Used on resistance welding machines with electrodes driven by electric motor.

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.

Method and apparatus for joining metal components with mitigation of residual stresses

Abstract: A welding process and an apparatus used therein for providing a significant improvement in the detrimental tensile residual stress condition on the root side of welds, especially on the inside wall of piping welds. The method combines an extremely thin weld joint design with a non-circular cylindrical, thin welding electrode having an elongated cross-sectional shape. During welding, the elongated dimension is aligned parallel with the length of the weld joint. This combination enables joining of piping and other residual stress-sensitive components with both the initial weld joint preparation and the completed weld having a uniquely thin width and with a high aspect ratio of depth to width. Use of this high-aspect-ratio weld joint process substantially mitigates welding-induced residual stresses, without the normally required internal water cooling. The process is considered to be effective in mitigating residual stresses and the associated welding strains (distortion) in joints having any path shape, whether welded from one or more sides of the material.

Crimp metal fitting for electric wire

Abstract: PURPOSE:To depress the deterioration in electrical wires, and electrodes for resistance welding and to reduce contact resistance with a low electric current by forming a crimp metal fitting pressed against the core wire parts of the electrical wires for resistance welding of a metal material having conductivity lower than that of brass. CONSTITUTION:A copper alloy having low conductivity such as a low- conductivity iron-based alloy such as SUS304 or german silver is used as a metal material for a crimp metal fitting 3 for electrical wire for connecting electrical wires 1, 2 to each other. Mechanical crimping by means of a pressure device is applied to the crimp metal fitting. Resistance welding is then applied to the crimp metal fitting to melt with and connect to core wire parts 1b, 2b. In this case, effective heat generation is developed by flowing a welding current since the SUS304, the german silver, etc., have lower conductivity compared with brass. Thus, the core wire parts 1b, 2b are melted and connected at a low welding current in a short time to reduce contact resistance.