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Showing papers on "Electric resistance welding published in 1984"


Book
01 Jan 1984
TL;DR: In this paper, the authors describe electric arc welding, high energy density welding, and future developments of welding processes, and discuss the benefits of better understanding of the physics of welding.
Abstract: Greater understanding of the physics of welding is leading to improved application and control of welding processes. Further gains in welding productivity could follow. Electric arc welding, high energy density welding and future developments are described

656 citations


Patent
23 Apr 1984
TL;DR: In this paper, the weld line can be tracked either by bouncing a beam of light off the welding electrode so as to form an illuminated area and detecting the resulting irregularity where the illuminated area crosses the welding line, or by detecting the deformation in the surface of the weld pool as the pool flows into the gap between the metal portions being joined.
Abstract: Video data generated at a high rate by a camera observing a welding operation is selectively stored in a video-computer interface to permit later computer analysis of the data. Special multiple memory techniques can be employed when the rate of which the data is generated is too fast for storage in a single memory in the interface. The width of the weld pool is detected by finding local minima of light intensity associated with these edges. The mass of the weld pool and the weld penetration can be measured and controlled by causing oscillations in the weld pool and measuring the natural frequency of such oscillations. The weld line can be tracked either by bouncing a beam of light off the welding electrode so as to form an illuminated area and detecting the resulting irregularity where the illuminated area crosses the weld line, or by detecting the deformation in the surface of the weld pool as the pool flows into the gap between the metal portions being joined. Prior to welding, the weld line can be detected by establishing a low power welding arc insufficient to create a molten weld pool but generating enough light to produce an irregularity in the reflected light at the location of the weld line.

132 citations


Patent
31 Oct 1984
TL;DR: In this paper, a method of laser welding sheet metal protected by using low-vaporizing-temperature materials was proposed, whereby, before being subjected to a laser welding beam along a weld area, two metal sheets are placed on top of each other in such a manner that at least one layer of the said protecting material is located between the sheets at the weld area and that the welding area communicates directly externally of the weld surface between the two sheets whereby gases generated by vaporization of said protective material may escape from the weld areas.
Abstract: Method of laser welding sheet metal protected by using low-vaporizing-temperature materials, whereby, before being subjected to a laser welding beam along a weld area, two metal sheets are placed on top of each other in such a manner that at least one layer of the said protecting material is located between the sheets at the weld area and that the weld area communicates directly externally of the weld area between the sheets whereby gases generated by vaporization of said protective material may escape from the weld area.

58 citations


Patent
11 May 1984
TL;DR: In this paper, a non-uniform pressure distribution and non-parallel welding surface over at least a portion of the resulting weld near the outside edge are used to increase the lip compliance and reduce the effective pressure of molten material acting on the lip during welding.
Abstract: Joints between thermoplastic parts are friction welded (e.g., as by vibration welding) or otherwise thermally welded in such a manner that a non-uniform temperature distribution results during welding which effectively blocks flash flow from the edge of the joint, and upon cooling, produces a joint that is at least partially stress relieved and is resistant to solvent-induced crazing and cracking. Joints may employ nonparallel adjoining surfaces and/or flexural lips, which bend slightly under pressure applied during welding so as to produce a non-uniform pressure distribution and nonparallel welding surface over at least a portion of the resulting weld near the outside edge. In addition, one or more axial grooves may be used to isolate the nonparallel or lipped area of the weld from the remainder of the weld area so as to increase the lip compliance and reduce the effective pressure of molten material acting on the lip during welding.

45 citations


Patent
30 Apr 1984
TL;DR: In this paper, an integral spot resistance welding gun and transformer unit are mounted on an end of a robot arm actuator to provide a mounting for a sliding gun cylinder having a piston connected to one of the lower jaw electrodes.
Abstract: An assembly is provided for mounting on an end of a robot arm actuator as an integral spot resistance welding gun and transformer unit. A gun slide support bracket is connected to the transformer and serves to provide a mount for a sliding gun cylinder having a piston connected to one of the jaw electrodes. The lower jaw is removably connected to the cylinder. Roller shunts are used to provide electrical connection between secondary terminals on the transformer and the two electrodes. A proximity switch assembly is advantageously utilized to provide signals to the robot controller indicating a fully retracted position of the jaws.

43 citations


Patent
15 May 1984
TL;DR: In this paper, the major flux ingredients are lithium oxide, iron oxide, silicon dioxide, lithium carbonate, magnesium and aluminum metal powders, all in a carefully balanced formula to give excellent operator appeal and excellent slag removal.
Abstract: A formulation for the flux in a cored-type electric arc welding electrode which produces high impact value welds while welding vertically up or overhead and at greater melt-off rates than heretofore. The major flux ingredients are lithium oxide, iron oxide, silicon dioxide, lithium carbonate, magnesium and aluminum metal powders, all in a carefully balanced formula to give excellent operator appeal and excellent slag removal.

39 citations


Patent
26 Sep 1984
TL;DR: In this paper, a hot wire TIG welding apparatus has a current detector for detecting the peak period and base period of the arc current, and the welding apparatus further has a controller which controls, in response to the detection signal from the current detector, the operation of the wire heating power supply.
Abstract: A hot wire TIG welding apparatus has a current detector for detecting the peak period and base period of the arc current. The welding apparatus further has a controller which controls, in response to the detection signal from the current detector, the operation of the wire heating power supply such that the wire heating power is supplied only during the base period of the arc current. According to this arrangement, a hot wire switching TIG welding apparatus can be produced using commercially available power supply systems for TIG arc welders, without requiring substantial change or modification of the control circuits in the TIG arc welders.

31 citations


Journal ArticleDOI
TL;DR: In this article, a theoretical and experimental study of heat flow during the welding of pipes was carried out, where the theoretical part involves the development of two finite difference computer models: one for describing steady state, 3-dimensional heat flow in seam welding, the other for describing unsteady states, 3D heat flow, during girth welding.
Abstract: A theoretical and experimental study of heat flow during the welding of pipes was carried out. The theoretical part of the study involves the development of two finite difference computer models: one for describing steady state, 3-dimensional heat flow during seam welding, the other for describing unsteady state, 3-dimensional heat flow during girth welding. The experimental part of the study, on the other hand, includes: measurement of the thermal response of the pipe with a high speed data acquisition system, determination of the arc efficiency with a calorimeter, and examination of the fusion boundary of the resultant weld. The experimental results were compared with the calculated ones, and the agreement was excellent in the case of seam welding and reasonably good in the case of girth welding. Both the computer models and experiments confirmed that, under a constant heat input and welding speed, the size of the fusion zone remains unchanged in seam welding but continues to increase in girth welding of pipes of small diameters. It is expected that the unsteady state model developed can be used to provide optimum conditions for girth welding, so that uniform weld beads can be obtained and weld defects such as lack of fusion and sagging can be avoided.

30 citations


Patent
Heinz Eisinger1
02 Mar 1984
TL;DR: In this paper, a method and equipment for welding sheet metal flanges, in particular of semimonocoque sections of a fuel tank, by means of a laser beam, is presented.
Abstract: With a method and equipment for welding sheet metal flanges, in particular of semimonocoque sections of a fuel tank, by means of a laser beam, the flanges to be welded are pressed together by means of an overlay and a holding-down clamp adjacent to the site intended for the weld seam, so as to produce gap-free contact of the sheet metal flanges with one another at the site intended for the weld seam A satisfactory, gas-tight weld joint of the two flanges is thereby produced The disadvantages associated with the previously used electrical resistance welding (roller seam welding), such as loss of strength and susceptibility to corrosion at the weld site, are avoided

29 citations


Patent
29 May 1984
TL;DR: In this article, a method and apparatus for detecting weld nugget growth on a workpiece during a welding operation using a resistance spot welding gun is described, where a piston rod is mounted in a cylinder and is connected at one end to an electrode of the gun.
Abstract: A method and apparatus are disclosed for detecting weld nugget growth on a workpiece during a welding operation using a resistance spot welding gun. In the preferred embodiment, a piston rod is slidably mounted in a cylinder and is connected at one end to an electrode of the gun. The opposite end of the piston rod extends rearwardly through the cylinder and is coupled to a sensor assembly for detecting the amount of movement of the piston rod created by weld nugget growth on the workpiece during the welding cycle.

27 citations


Patent
Dieter Schmid1
17 Dec 1984
TL;DR: In this paper, a battery grounding terminal is formed by welding a metal component to form a portion of the battery grounding terminals, where the metal component is tinned or galvanized with an anti-corrosion metal coating.
Abstract: A weld-on nut is welded to a metal component to form a portion of a battery grounding terminal. The weld-on nut is tinned or galvanized with an anti-corrosion metal coating. The weld-on nut is welded to the associated sheet metal component by means of an electric resistance welding operation. In order to protect the contact surface from fusion of the tinning by welding spatters, an electrode contact surface on the nut is arranged axially offset relative to an electrode abutment surface or transversely to the latter. This weld-on nut can be of extremely light and small construction. The nut also requires provision of only a relatively small centering hole in the sheet metal in the region of the welding position, whereby the sheet metal component is only very slightly weakened.

Patent
19 Nov 1984
TL;DR: In this paper, a laser welding method and an apparatus for welding stacked coated members (1, 2) were presented. But the method was not suitable for the case of base members. And the welding process was performed on a metal having a lower melting point than the base.
Abstract: A laser welding method and apparatus for welding stacked coated members (1. 2 1 in which voids in the welds are positively eliminated. A spacer (14) is disposed between the two members (1, 2) to be welded. This provides a path (16) for discharging gas formed by heating the coating matenal. The method and apparatus of the invention are useful for the laser welding of base members coated with metals having a lower melting point than the metal of the base, paints and oils. Preferably, the width of the gap is in a range of 0.1 mm to 0.5 mm.

Patent
24 Feb 1984
TL;DR: In this article, a resistance welding method is described, including the steps of contacting electrodes to two parts to be welded together, faying the two parts at a location, and passing electrical current between the electrodes and through said location, wherein the improvement comprises, on the parts, a roughened surface means for decreasing heat generation where an electrode makes contact and at the faying location, the coating means performing the function of generating heat to form a nugget without expulsion.
Abstract: A resistance welding method, including the steps of contacting electrodes to two parts to be welded together, faying the two parts at a location to be welded, and passing electrical current between the electrodes and through said location, wherein the improvement comprises, on the parts, a roughened surface means for decreasing heat generation where an electrode makes contact and a uniform coating means at the faying location, the coating means performing the function of generating heat to form a nugget without expulsion.

Patent
07 Mar 1984
TL;DR: In this article, the authors proposed a method to stabilize a welding arc and prevent generation of a welding defect by detecting short circuit and detachment of a droplet, controlling welding current and oscillating a welding torch in the axial direction of the top end of the welding wire.
Abstract: PURPOSE:To stabilize a welding arc and to prevent generation of a welding defect by detecting short circuit and detachment of a droplet, controlling welding current and oscillating a welding torch in the axial direction of the top end of a welding wire CONSTITUTION:The voltage from a welding power source 7 is impressed between a welding wire 2 and objects 6 to be welded through a wire feeder 5, a welding torch body 11, etc by which welding is progressed A voltage decider 17 judges the short circuit or detachment of a molten metal upon receipt of information from a welding voltage detector 16 and outputs a signal to an electromagnet controller 19 and a power source controller 29 On the other hand, the controller 19 controls the polarity change-over of the current flowing in an electromagnet 15 according to the time set in a time setter 18 with the signal from the decider 17 as a trigger The controller 20 controls also a welding power source 7 according to the time set in a time setter 18 with the signal from the decider 17 as a trigger thereby increasing or decreasing the welding current

Journal ArticleDOI
TL;DR: In this article, a model law for matching is derived from this and illustrated with an example, and a theoretically derived joining displacement equation is shown for the connection process, where the influence of temperature and pressure on joining displacement is estimated.

Patent
05 Nov 1984
TL;DR: In this paper, a method of fabricating a projection for resistance welding is described, which involves fabricating the projection at the workpiece by plastic deformation of the basic material and dimensionally exactly shaping the projection by compression molding of the flowable metal between a punch and die of a tool.
Abstract: A method of fabricating a projection for resistance welding contemplates fabricating the projection at the workpiece by plastic deformation of the basic material and dimensionally exactly shaping the projection by compression molding of the flowable metal between a punch and die of a tool.

Patent
08 Nov 1984
TL;DR: In this article, a welding apparatus for fabricating wire grids for concrete reinforcement purposes, in which the longitudinal and cross wires are welded at the intersections, was described, and each electrode pair, consisting of top and bottom electrode (20, 23), forms together with a welding transformer (15) and if need be a longitudinalwire feed mechanism (18) a unit movable individually on a rail (4).
Abstract: The invention relates to a welding apparatus for fabricating wire grids for concrete reinforcement purposes, in which the longitudinal and cross wires are welded at the intersections. Each electrode pair, consisting of top and bottom electrode (20, 23), forms together with a welding transformer (15) and if need be a longitudinal-wire feed mechanism (18) a unit movable individually on a rail (4). All welding units (31-42) can be coupled to a transport spindle (8) by a transport nut (29b) in order to be moved on the rail (4) for a desired amount of travel. The individual mobility of the individual welding units (31-42) permits an infinitely variable and quick adjustment of the longitudinal-wire spacing.

Patent
30 Nov 1984
TL;DR: In this paper, the arc voltage is sensed to provide a signal for controlling the frequency of the welding current pulses to counteract variations in electrode wire feed speed or spacing of the electrode from the workpiece.
Abstract: A method of pulsed arc welding and an apparatus for carrying out the method, employ welding current pulses having an amplitude greater than the value of a background current. The arc voltage is sensed to provide a signal for controlling the frequency of the welding current pulses to counteract variations in electrode wire feed speed or spacing of the electrode from the workpiece.

Patent
09 Mar 1984
TL;DR: In this article, a flat electrode post is pushed into a passing hole of a partition of a container with cone-shaped welding electrodes, and current is passed to both posts 3 and 3' to weld them.
Abstract: PURPOSE:To provide a lead-acid battery having good airtightness in a passing hole by pushing out a flat electrode post into a passing hole of a partition of a container with cone-shaped welding electrodes, then by performing resistance welding. CONSTITUTION:An electrode group having flat electrode posts 3 and 3' is inserted in a container which has a passing hole 2 in its partition 1. Cone-shaped welding electrodes 4 and 4' which has a top angle theta of 90-150 deg. and a 1-2mm. larger base diameter D than the passing hole diameter d are pushed from the back of both electrodes 3 and 3' facing the passing hole 2 to deform the electrode posts 3 and 3' in a cone shape. The electrode posts 3 and 3' are pushed out into the passing hole 2 and brought into contact each other, then current is passed to both posts 3 and 3' to weld them.

Patent
10 Nov 1984
TL;DR: In this paper, an auxiliary electrode 9 is brought into contact with the bottom face of a metallic plate 2b, and at the same time, a reaction receiver 10 is brought to contact with a metal plate 2a, and current is let flow between an electrode 5' and the auxiliary electrode 8' to form a metal body.
Abstract: PURPOSE:To widen the range of use of a composite material by resistance- welding an outer face metallic material and a body made of metal, and after softening thermoplastic material and removing it, making the resistance-welding of metallic materials. CONSTITUTION:An auxiliary electrode 9 is brought into contact with the bottom face of a metallic plate 2b, and at the same time, a reaction receiver 10 is brought into contact with a metallic plate 2a, and current is let flow between an electrode 5' and the auxiliary electrode 9. The metallic plate 2b and the body made of metal 4 are resistance-welded by the welding current and deposited metal 8' is formed. At this time, metallic plates 2a, 2b and thermoplastic material are softened by welding heat, and by strong pressure contacting with electrodes 5, 5' the insulating plastic substance 3a is removed, and at the same time, the resistance-welding of metallic plates 2a, 2b and the body 4 is completed. By such a way, various weld joints become possible, and the range of use of the composite material is extended.

Patent
13 Mar 1984
TL;DR: In this article, the secondary voltage and electric current of a power transformer are monitored to prevent degradation in welding quality and reduce equipment cost by monitoring the secondary voltages and electric currents of each welding machine.
Abstract: PURPOSE:To prevent the degradation in welding quality and reduce equipment cost by monitoring the secondary voltage and electric current of a power transformer, and controlling the electricity conduction timing for each welding machine in such a way that the load current does not exceed set values. CONSTITUTION:A potential transformer 31 and a current transformer 32 are provided on the secondary side of a power transformer 20, and the secondary voltage and current of the transformer 20 are inputted respectively to a voltage detecting part 33 and a current detecting part 34. These data are inputted to a permissible current detecting part 35, by which the secondary current lowering below the permissible drop voltage is calculated. This current value is inputted to a welding machine selection command part 37. The welding conditions for materials 11a-11z to be welded are beforehand set in a welding condition setting part 40 for every welding machine. The start signals for the respective welding machines are inputted to a start command input part 36, and in a command part 37, the permissible current value and the sum of the set current values of the welding machines inputted with the start signal and the set current values of the welding machines under working are compared. When the permissible value is large, electricity is conducted to the welding machines simultaneously, and if it is smaller, the welding is started after the end of the electricity conduction to the other welding machines.

Proceedings ArticleDOI
01 Feb 1984
TL;DR: In this article, the welding current, voltage, force, and nugget displacement is monitored to assist in the evaluation of optimum process and material characteristics, which is used in conjunction with the optimization of the weld process parameters to provide the widest range of acceptable welding conditions.
Abstract: Zinc coating integrity, composition, thickness, roughness, and the presence of Fe-Zn intermetallics are being investigated with regard to the mechanism of weld nugget formation. This information is being used in conjunction with the optimization of the weld process parameters; such as upsloping, downsloping, preheating, postheating, and double pulsing, to provide the widest range of acceptable welding conditions. Dynamic inspection monitoring of the welding current, voltage, force, and nugget displacement is being used to follow the progression of nugget formation and to assist in the evaluation of optimum process and material characteristics. It has been found that hot-dipped galvanized materials with coatings which have a very thin Fe-Zn alloy layer, have a wider range of acceptable welding conditions than the commercial galvannealed products, which have a fully alloyed Fe-Zn coating. Small variations in the thickness and roughness of the G90 hot-dipped coatings studied seem to have no significant effect on the welding current range. Upsloping and downsloping of the weld current increases the welding range of hot-dipped products when using truncated cone electrodes, whereas sloped current has no advantage for galvannealed or uncoated materials. Radiused electrodes can increase the lobe width of hot-dipped products but are not beneficial when using slopedmore » current or when welding galvannealed or uncoated materials.« less

Patent
19 Nov 1984
TL;DR: In this article, a process for checking the welding time of an electrically weldable joint with two tubes (2, 2') to be assembled, characterized in that it consists of sensing the variations of one property of the material to be welded, in such a way that at the instant when welding is completed, the value of this property is used as information supplied by the sensor for controlling the interruption of the welding current.
Abstract: 1. Process for checking the welding time of an electrically weldable joint with two tubes (2, 2') to be assembled, characterized in that it consists of sensing the variations of one property of the material to be welded, in such a way that at the instant when welding is completed, the value of this property is used as information supplied by the sensor for controlling the interruption of the welding current.

Patent
28 Feb 1984
TL;DR: In this article, the authors proposed a method to shift molten metal in the state of small lump without stopping a large quantity of molten metals at the tip of a wire, and to stabilize the arc preventing generation of spatter by changing speed of feeding of the welding wire in synchronization with the period of pulse current.
Abstract: PURPOSE:To shift molten metal in the state of small lump without stopping a large quantity of molten metals at the tip of a wire, and to stabilize the arc preventing generation of spatter by changing speed of feeding of the welding wire in synchronization with the period of pulse current. CONSTITUTION:In consumable electrode type pulse arc welding, the welding wire 12 is melted by a welding arc 21 and forms molten metal 12a. The molten metal 12a is accumulated at the tip of the wire 12, and at the same time, the wire 12 is fed toward an object to be welded 14. At this time its current value increases. From this state, the feeding speed of the wire 12 is reversed. That is, the wire 12 is shifted in the direction going away from the object to be welded 14, and the molten metal 12a is separated and shifted forcibly by inertia. As force of inertia due to change of feeding speed of the wire is given to the molten metal 12a in addition to pinch effect of pulse peak current, sure separation and shifting are made from the state of small lump. Accordingly, a beautiful bead free from welding defect can be obtained.

Journal ArticleDOI
M. Kaplan1, A. Tslaf1
TL;DR: In this paper, a criterion of weldability of contact materials in adiabatic ransient conditions is determined as a quantity which is directly proporional to the square root of the Joule veiding integral and inversely proportional to the contact material hardless at the temperature before the transient process starts.
Abstract: A criterion of weldability of contact materials in adiabatic ransient conditions is determined as a quantity which is directly proporional to the square root of the adiabatic welding integral (i.e., the Joule veiding integral) and inversely proportional to the contact material hardless at the temperature before the transient process starts. In the range of he rated operating temperatures, the criterion appears to be almost independent of the welding integral for the most practical contact metals beause of the coincident reduction in hardness. The values of this criterion are calculated and compared versus a similar criterion for the steady-state egime, for most metals, a number of alloys, and some of the sintered compounds usually applied in contact design.

Book ChapterDOI
01 Jan 1984
TL;DR: In this article, the authors studied the change in gap width and the risk for hot cracking in butt-welding of tack welded plates and concluded that the most important welding parameters are the welding speed, the arc energy per unit length of the weld and the number of tackwelds for a given length of a weld.
Abstract: Submerged-arc welding is studied with special attention to hot cracking and to change in gap width in butt-welding of tack-welded plates. The most important welding parameters are the welding speed, the arc energy per unit length of the weld and the number of tack-welds for a given length of the weld. Eight cases are analyzed using the finite element method. The change in gap width and the risk for hot cracking are studied for two different values of each of these welding parameters. It is concluded that it is possible to find a practical combination of welding parameters that minimizes the change in gap width. The welding speed in that combination should be fairly high. The location of the maximum value of calculated change in mechanical strain across the weld, , agrees well with available experimental observations of the location of that crack front which is closest to the edge in the end portion of butt-welded plates. The transverse stresses become compressive at the edge and tensile at a short distance (about 0.1 m) from the edge shortly (about 30 s) after removal of the heat source. Therefore it is believed that the hot cracks nucleate at temperatures around 1200°C due to high transverse strains and then propagate towards the interior of the plate due to the transverse tensile and compressive stresses. It is then concluded that the highest risk for hot cracking is to be found at the end portion of the butt-welded plate for low welding speeds and large values of the arc energy per unit length of the weld.

Book ChapterDOI
01 Jan 1984
Abstract: Following difficulties with heat–to–heat variation in weld penetration enountered during GTA welding of stainless steel tubing, a program was undertaken to identify the cause of the problem and to develop remedial techniques. The variation in weld penetration was attributed primarily to differences in sulphur and, to a lesser extent, oxygen content, in broad agreement with a published model for such effects based on surface tension. The incorporation of copper alloy heat sinks into the standard welding head was successful in overcoming the problem. Both argon − 1% oxygen shielding gas and multipass welding procedures have been demonstrated to be promising alternative solutions, but these techniques have not been fully developed. To prevent the recurrence of the problem in future construction, a limit of 100–200 ppm sulphur has been included in the material specification for tubing purchases.

Patent
07 Feb 1984
TL;DR: In this paper, the deformation of the welding area and the neighboring areas of the metal sheets was proposed to avoid shrinkage cavities and prevent welding strains by plastic deformation in the area.
Abstract: The welding speed of plastically deformable materials when using high power density energy sources, for example a focused laser beam (34) is limited by the formation of defects (cracks, shrinkage cavities, pinholes etc.) in the welding or closed to the latter (butt-joint 11). In order to increase the welding speed while avoiding those defects, the present invention proposes the deformation of the welding (butt-joint welding 11) and the neighbouring areas of the metal sheets (14, respectively 15) so as to press the melted mass formed for the welding and provided by the welding seam, to avoid shrinkage cavities as well as pinholes and to prevent welding strains by plastic deformation in the butt-joint welding area (11). Simultaneously to the deformation of the butt-joint welding (11), it is possible to proceed to its smoothing.

Journal ArticleDOI
TL;DR: In this paper, Sumitomo Metals has successfully developed an Automatic Welding Control System, using Pattern Thermometer, Upset Gauge, etc, which were newly developed for this system.
Abstract: Recently, high quality Electric Resistance Welded Tubes (ERW Tubes) have been requested by the customers To meet this demand, the Sumitomo Metals has successfully developed an Automatic Welding Control System, using Pattern Thermometer, Upset Gauge, etc, which were newly developed for this system The results obtained by applying this system to a small size ERW tube mill are as follows:(1) Welding temperature was stabilized by computer according to the conditions of the tube size, material and welding speed(2) This system has been found to be useful for welding low alloy steel and high carbon steel which have more severe welding conditions

Patent
Gino Luigi Leone1
02 May 1984
TL;DR: In this paper, a process for preparing aluminum sheet for resistance welding is described, which increases the useful life of the welding electrodes used for welding the thus prepared sheet, thereby creating a differential in oxide thickness between the surfaces of the sheet.
Abstract: A process is described for preparing aluminum sheet for resistance welding, which increases the useful life of the welding electrodes used for welding the thus prepared sheet. The process comprises the steps of: (a) treating both surfaces of the sheet portion to be welded to remove the non-uniform mill finish oxide layer and provide clean surfaces, and (b) providing a thin oxide layer on one cleaned surface and a thicker oxide layer on the other cleaned surface of said sheet, thereby creating a differential in oxide thickness between the surfaces of the sheet and hence a differential in surface resistance.