Showing papers on "Spot welding published in 1970"

Resistance welding of sheet metal coated with layers

Abstract: The invention relates to a method for the resistance welding of sheet metal coated with layers, wherein firstly electrical contact is established between the sheets to be interwelded and between the welding electrodes and said sheets, and subsequently welding is effected across the coating layers The invention relates also to machines for carrying out this method

Method of monitoring a welding operation

Abstract: A method of monitoring a spot welding operation of two overlapping pieces includes transmitting and receiving ultrasonic shear wave pulse signals into and from the two pieces while the welding operation is being performed. Means are then provided to indicate the degree of penetration of the weld into the pieces.

Mode of failure of resistance spot welded martenstic stainless steel- part ii

Abstract: Martenstic Stainless Steels are potential material for automobile industry. Martenstic stainless steel can be resistance spot welded either in annealed or in hardened & tempered condition. Regardless of the condition, welding produces a hardened martenstic zone adjacent to weld. Hardness of this zone, though controlled to an extent by welding procedure, depends mainly on carbon content. As the hardness of metal in the heat affected zone increases, its toughness decreases and its susceptibility to cracking increases. Martenstic stainless steels having maximum carbon content of 0.15%, such as AISI grades 410 and 414, often produce satisfactory welds without post weld heat treatment. Steel with higher carbon content such as AISI grades 420 and 440 generally required post weld heat treatment mentioned by (Udin et al., 1954; ASM handbook, 1983).In the present investigation, 0.5 mm thin AISI 420 grade (0.29 % C) was selected for study. Cracking tendency ofthe material affects the mode of failure. Failure may occur either from interface (interface failure) or from nugget (Nugget pullout). Mode of failure was investigated by hand peel test, tensile shear test and cross tension test. Nugget pullout mode reveals the nugget has sufficient ductility and toughness and it is desired mode of failure. SEM images show that mode of failure is partially nugget pullout and partially interfacial. Insight from these studies will throw light on the mechanism of failure of resistance spot welds in martenstic stainless steel. Result indicates the faster cooling rate, higher carbon content, absence of post heating are responsible for cracking in the weld and subsequently interfacial failure.

Welding machine and method

Abstract: The invention relates to the welding of transverse rungs between longitudinal rods to form steel reinforcement, for concrete, known as ''''Bi-Steel'''' The rods are fed convergently and continuously through a resistance welding machine, the transverse rungs being successively positioned between the rods A pair of welding electrodes are thrust from opposite sides against the rods to clamp each successive rung in position during welding by sequential spot welding Each electrode travels around a closed path such that the electrode travels along with the rods when in contact therewith The contact between the electrodes and the rods is preferably rolling contact so that any discrepancy between the speeds of the rods and of the electrodes causes rolling rather than sliding of the electrodes along the rods The electrodes may be rollers mounted on rotating carrier discs between which the rods pass In one example each disc carries twelve roller electrodes each urged by a spring radially outwardly of the disc In another example two electrodes are used each mounted on a beam extending between a crank and a rocking arm

Sealed mesh material

Abstract: A net material of centimetre strips of polypropylene is fed round two heated rollers between sheets of polyethylene film. A bank of infra-red heaters provides heat directed by two angled sheets at the gap between the rollers to give a spot welding effect at the points of contact giving a sealed translucent meshed material.

Hand-operated spot-welding

Abstract: A loer tubular carrier arm for a welding electrode holder is rigidly connected to a pistol-shaped handle which has an operating lever and is constructed as an air-pressure cylinder. An upper tubular carrier arm for the holder of the second welding electrode is hinged onto the lower carrier arm and can be pivoted by a piston rod which is connected to a piston moved longitudinally in the air-pressure cylinder of the handle.

Method for supervising spot welding

Abstract: Spot welds are monitored for determining the quality of the weld by measuring the amount of shrinkage that occurs at the weld, beginning subsequently to the termination of the welding current. The amount of shrinkage is compared to the shrinkage of reference welds which are known to be satisfactory.

Steel wire cage wire for chemically prestressed concrete pipe

Abstract: A wire used in the wire cage of chemically prestressed concrete pipe is effective to restrain the expansion of expansion concrete over a wide range and with a uniform stress during the manufacture of the pipe. The plane of the wire which applies stress to the concrete is approximately straight or mildly curved in section, its width being larger than the diameter of a circular wire having the same cross sectional area and its thickness being smaller than said diameter. The plane which acts on the concrete is provided with projections for spot welding in the formation of the wire cage.

Resistance welding of sheet metal

Abstract: Resistance welding electrode is partic. suited to spot welding galvanised sheet metal and has a tungsten component on the surface which is placed onto the sheet metal. The tungsten component is provided with at least one alloy additive to prevent the growth of grain size crystals.

Resistance welding flat components to shafts

Abstract: Resistance welding flat components to shafts, particularly projection and point welding. Electrodes are directly connected. Angles or flats are given projections by projection welding; flats have grooves of V-shaped or semicircular section, and latter may have internal projection, and are projection-weldable butted to the shaft. Flats with holes are axially projection welded to pinch-welded projections on shaft sleeve surface, determining radial location on shaft. Alignment slots can be used so that the flat part is removable, by welding several flat parts, over the pinched projections according to dimensions of alignment slots.

Method of multiple spot welding

Abstract: The invention relates to a method of and apparatus for electric welding using a non-consumable electrode. It envisages the modulated movement of an electrode so that it moves in regular increments and produces a continuous weld constituted by a series of spot welds which overlap by a predetermined and regular extent, and may include also the modulation of electric current in combination with the modulated movement of the electrode.

Process for joining wires to sheets of refractory materials

Abstract: A tungsten reflector for a regenerative lamp is secured to a tungsten support rod by cross wire welding a molybdenum wire to the support rod and inserting the free end of the wire into an opening in the sheet and finally arc spot welding the free end of the wire to the side of the sheet facing away from the support rod.

Garment guard covers

Abstract: Coat-hanger covers produced from folded weldable sheets by making deep weld along outer contour of covers, enabling the excess to be torn away. The insertion opening is made tearproof by use of welds and the outer contour of the cover between the welds and the welding station is cut automatically. The apparatus has an upper electrode interrupted by the insertion opening an insulating blade, and a spot welding electrode. A relatively movable lower aluminium electrode has a corresponding blade.

Dynamic spot welder

Abstract: Dynamic electrical resistance spot welding apparatus according to the present invention comprises a support that may be of linear or circular configuration and defines an elongated work station. Strip material to be spot welded moves continuously through the work station and may be wound about a circular mandrel that may form the support. A rotatable welding element which may be a wheel is disposed with its periphery adjacent the work station and is provided with a plurality of recesses formed about the periphery thereof. Each recess retains a welding head in movable relation therein that is biased outwardly away from the recess so that the welding head may move against the bias upon contacting the material to be welded. Each welding head is provided with a pair of electrodes that are connected electrically to a source of electrical potential through a pair of brushes carried by the welding element. The electrical circuitry is completed upon engagement between the electrodes and the material and welding is accomplished by heat developed by the electrical current passing through the resistance defined by the material. The welding heads engage the material in such manner that mechanical pressure is varied throughout movement of the material through the work station to achieve heating, fusion, and solidification of the material under mechanical pressure as it moves through the work station. Additionally, the electrical circuitry may be provided with a timing control to achieve heating and cooling of the material as it moves through the work station if desired.

The influence of welding parameters and corrosive environment on the joint strength of resistance sp

Abstract: In the present work, mild steel sheets consisting two batches were welded by resistance spot welding at different welding parameters and exposed under different environments. The 5% sodium chloride brine was used in the salt spray test, produced a whole rusty surface on the tested specimens (batch 2). The welding joints were subjected to tensile-shearing test in order to determine the strength of the welded joints from ambient and in corrosive environment. Tensile-shear test showed significant differences on the failure load between these two batches where corrosion had affected the surface strength of the welded steel. The results also showed that the highest tensile shear strength is given by the specimen welded using 4kA current at 4 cycles. Keywords: mild steel, spot welding, microstructural, tensile shear test INTRODUCTION Resistance spot welding is usually used in the fabrication of sheet metal assembly. It can be used to weld materials such as low carbon steel, nickel, aluminum, titanium, copper alloy, stainless steel and high strength low alloy steel. Resistance spot welding process is most applicable in the industrial fields of manufacture and maintenance (car industry, aerospace and nuclear sectors, electronic and electric industries [1], [2], [3]. The static strengths of spot welds have also been explored. Mechanical tests of spot welds in tension–shear, direct tension, torsion and peel specimens were also reported [1]. Currently, mild steels are mostly used in applications where demands for corrosive protection are put forward. The most common cases reported were erosion corrosion. The aim of this present paper is to study on spot welded of mild steel towards variety of welding parameters (welding current, welding cycle) in ambient and corrosive environment.