Showing papers on "Spot welding published in 1979"

Method of ensuring the maintenance of constant quality of spot welds

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

Method of welding nuclear reactor fuel assemblies

Abstract: A method of welding tabs projecting outwardly from grip straps in a fuel assembly grid to a control rod guide thimble positioned in a cell in the grid including providing a weld guide having openings therein which receive dimples on the strap when the weld guide is placed in a cell adjacent to the cell containing the control rod guide thimble. THe weld guide includes an opening which falls into alignment with a tab so that when a welding gun electrode is placed through the opening and into contact with a tab, the other electrode is automatically centered on its tab thus permitting accurate spot welding of the parts. To make a second spot weld on the same tab but at a point outwardly from the first spot weld, a second weld guide having an opening therein displaced a greater distance from a reference point on the weld guide, is placed in the same cell and the welding process repeated.

Monolithic metal catalyst for exhaust gas detoxification - with metal foils joined by laser beam welding (SW 4.12.78)

Abstract: Parent patent described a monolithic metal catalyst for the detoxification of the exhaust gases of i.c. engines e.g. of motor cars, in which corrugated metal foils are joined up to form a solid element. In this addn. this operation is effected by laser beam welding. Process facilitates the joining of the corrugated metal foils by a seam or spot weld, and also the fixture of the insert to the casing by a fillet weld at the open end.

Ultrasonic method of inspecting spot welds

Abstract: To obtain a measure of the size of a spot weld nugget, the weld is scanned with an ultrasonic beam of about 20 megahertz frequency. The ultrasonic signal transmitted through the part is analyzed to determine the presence of the part and the presence of a weld. The detected signal is gated to pass a portion of the signal which has been multiply reflected through the weld region to a bandpass filter which passes frequencies that are selectively attenuated by a weld nugget much more than the surface bond or stick zone surrounding the nugget so that the energy content of the filtered signal is used to determine the presence of nugget material at any point during the scan. A chart recorder controlled according to the energy content of the filtered signal produces a characteristic signature for each weld which distinguishes between the extent of the stick zone and the nugget of each weld so that the weld nugget size is readily determined.

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

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

Spot welding method

Abstract: PURPOSE: To automate the dressing work of spot electrodes and achieve the automation and rationalization of spot welding work by inserting an electrode plate between the electrodes and welding works and performing spot welding. CONSTITUTION: A cylinder ram 9 is operated to lower an upper electrode 1 and the welding works 21, 22 are pressed and supplied with electric current by the upper electrode 1 and lower electrode through an endless electrode 14. The electrode plate 14 is rotated and moved in the arrow 20 direction automatically by a feed motor 19 and feed rollers 18 after the spot welding and the stains by the pickup of the electrode plate 14 produced at the spot welding are cleaned by cleaners 15, thus the plate 14 makes contact with the welding works 21, 22 and upper electrode 1 or lower electrode in an always clean state. The plate 14 having been used for the spot welding is corrected of deformations by straightening rollers 17 and is repeatedly used. COPYRIGHT: (C)1980,JPO&Japio

Spot Weldability of High Strength, Cold Rolled Steels

Abstract: Four high-strength, low alloy (HSLA) steels with a 275 MPa minimum yield strength, were evaluated for spot weldability. The effects of variations in electrode diameter, electrode force, hold time, weld time, and weld coupon dimensions on strength, impact toughness, and nugget characteristics were examined by independently varying single welding parameters. Within the ranges studied, electrode diameter and force, and hold time were found to have minimal effects. Steel composition has a significant effect on both tensile-shear and cross-tension strength. Differences in base steel resistivity caused by compositional changes may cause changes in the current level required to achieve a specified nugget diameter. Usable current range was found to be a function of weld time and electrode force. An examination of spot welds made with automotive weld schedules showed that only schedule C (Chrysler), with significantly higher levels of welding current and electrode diameter, produced increased weld strengths. Neither nugget fracture appearance or minimum tensile-shear strength values alone were reliable indicators of overall weld quality. It was concluded that to facilitate the utilization of high strength, cold rolled steels and still ensure spot weld integrity, different criteria should be emphasized, including the attainment of an average nugget diameter of sufficient size to produce values of tensile-shear and cross-tension strength specified relative to values established for plain carbon steels.

Non-marring spot weld tip

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

Method and apparatus for non-destructive quality testing of spot welds

Abstract: A method of non-destructive quality testing of spot welds resides in that in the test weld nugget region there is produced a primary electromagnetic field inducing eddy currents in that region. Thereupon, the primary electromagnetic field is displaced in a direction parallel to the surface of contact of the welded parts. The phase angle between the resultant and primary magnetic fields is measured at the points characterized by the maximum of the primary electromagnetic field intensity lying on the same line parallel to the surface of the test weld and located in the zone disposed between the points located on either side of the test weld zone wherein the weld nugget is disposed, the weld nugget thickness is evaluated from the difference between the maximum phase value of the intensity measured in the test weld zone wherein the weld nugget is absent and the minimum phase value of the intensity measured in the test weld zone wherein the weld nugget is disposed. The weld nugget diameter is evaluated from the length of the zone within the limits where the phase of the intensity has its minimum value. An apparatus for non-destructive quality testing of spot welds includes a sinusoidal voltage generator with a phase shifter and an unbalanced bridge circuit having a superimposed eddy current transducer included into one of its branches, which are connected to the output thereof, and the outputs of the phase shifter and unbalanced bridge circuit being connected with the respective inputs of a phase meter, the superimposed eddy current transducer being complete with an attachment for its mechanical displacement in the plane parallel to the surface of contact of welded parts.

Absorber for a solar collector

Abstract: The collector comprises two thin stamped metal sheets, joined together by welding at their periphery, between which flows a heat-carrying liquid and is characterized in that said metal sheets are stamped with repetitive patterns whose concave surfaces are disposed opposite each other, but with staggering in their plane equal to approximately half a pitch, and in that the flat unstamped parts of said metal sheets are joined together by spot welds disposed substantially symmetrically and evenly in relation to said patterns. This collector is capable of resisting high pressures of the heat-carrying liquid.

Arc spot welding of thin plate structure

Abstract: PURPOSE:To enhance the reliability of welding by preventing the deformation of thin plate structure by procedure in which arc spot welding torch is put on the reingorcing material side with perforated hole and welding is made while cooling it from the side of outside plate. CONSTITUTION:The perforated hole 5 having a fixed diameter determined by the thickness of the outside plate 1 is bored at a point to be welded of the reinforcing matrial 2. The reinforcing material 2 and the outside plate 1 are combined, the arc spot welding torch 3 is put on the side of the reinforcing material 2, and the cooler 6 is symmetrically arranged on the side of the outside plate 1. When welding is made in this state, the perforated hole 5 is filled up with weld metal and thus the outisde plate 1 and the reinforcing plate 2 are exactly weded in a short time. And, the presenc of the perforated hole 5 reduces the amount of weld metal, so that the deformation of weld due to the coagulating contraction of theweld metal is smaller. In addition, the temperature rise of the outside plate 1 by welding heat can be suppressed by the cooler 6, and thus the deformation of weld can furthermore be reduced, raising the reliability of arc spot welding.

Spot weldability of dual-phase steel

Abstract: The spot welding characteristics of VAN-QN (80), a dual-phase HSLA (high strength, low alloy) steel, were examined with regard to the strength and ductility of spot welds under static, impact and cyclic loading and compared to a conventional V-N HSLA steel and SAE (Society of Automotive Engineers) 1008 low carbon steel. The maximum tensile shear strength of VAN-QN (80) spot welds was found to be proportional to the thickness and ultimate tensile strength of the base metal. VAN-QN (80) spot welds, therefore, were only slightly lower in strength than those in a conventional 80 ksi yield strength HSLA steel but up to twice the strength of welds in low carbon steel. Weld ductility was lower for VAN-QN (80) than for low carbon steel but greater than for conventional HSLA steel and increased with material thickness. The impact and fatigue properties of VAN-QN (80) welds were similar to those in conventional HSLA and low carbon steels. Weldability, as determined by the range of current over which acceptable welds could be produced, decreased with increasing thickness and was the same for VAN-QN (80) as for low carbon steel. The excellent weldability of VAN-QN (80) steel is attributed to a combination of the following properties: moderate hardenability, insensitivity of the dual-phase microstructure to softening by the heat inputs typical of spot welding, and a low yield strength to ultimate tensile strength ratio.

Series spot welder

Abstract: PURPOSE:To facilitate welding a variety of shape works, at least one pair of welder is installed in production line, back electrode with changeable electrode being attached under the welding position, and current is passed across in series. CONSTITUTION:A back electrode holer 98 is installed under the transfer line of automobile floor F, for example. Welders 3,3' are mounted on the rails 5, and an adaptable back electrode 88 is set in tunnel portion of the floor F. Both electrode tips 60, 60' of the welders 3,3' are set to the instructed positions. Second cables 61, 61' are connected with the electrode tips 60, 60', and current is passed the electrode tip 60 - the electrode 88 - the electrode tip 60' in series to make spot welding. This mechanism always provides the optimum welding condition for a variety of works different in demensions and shapes.

Zincciron alloyyelectroplated steel sheet for spot welding and pressing

Abstract: PURPOSE:To provide a zinc-iron alloy-electroplated steel sheet with superior press workability and spot weldability as well as good corrosion resistance and printability by electrolyzing a sheet in an electroplating bath contg. zinc and iron ions to electrodeposit iron and zinc in a specific ratio on the sheet surface. CONSTITUTION:A steel sheet is electrolyzed in an electroplating bath contg. zinc and iron ions to electrodeposit zinc and 7-80, pref. 10-65% of iron, thus providing a zinc-iron alloy-electroplated steel sheet for spot welding and pressing. For example, the sheet can be manufactured by carrying out electrolysis at a current density of 30 A/dm in a short time in a plating bath of pH 1-2 contg. about 250 g/l of FeSO4 7H2O, about 10-100 g/l of ZnSO4 7H2O and an adequate amt. of a pH regulator such as ammonium sulfate.

Controlling method for resistance spot welding

Abstract: PURPOSE:To improve the efficiency of operation and also, to enable to control the welding quality stably, by detecting the production of expulsion and surface flash during resistance spot welding and controlling welding current according to the value of current of production limit of expulsion and surface flash. CONSTITUTION:Detected signal of the sensor 16 is supplied to the comparison circuit 20 passing through the switch 18 and is compared with the standard voltage from the generator 24. Then, the signal is supplied to the monostable multivibrator 26 when the signal of sensor 16 is exceeded the standard voltage shown by detecting characteristics of expulsion and surface flash. Moreover, when the expulsion and surface flash are not produced, welding current is increased one stage by step-up control circuit 28 of the controlling circuit 12 by output signal from the vibrator 26. Also, when the expulsion and surface flash are produced, step-down control is carried out and the control decreasing the welding current one stage, is carried out. Hereby, the welding current is able to control according to the value of current of production limit of expulsion and surface flash and extremely effective welding is able to carry out.

Non-destructive testing of spot welds - via eddy current search coil and electronic circuit to measure length and thickness of welds

Abstract: A converter generating a prim. electromagnetic field (I) is moved over a spot weld and thus generates eddy currents creating a second magnetic field (II), which interacts with field (I) to produce a third field (III); and the intensity and phase of field (III) depend on the quality of the weld. The max. phase value (epsilon max) occurs where no weld is present, and the min. phase value (epsilon min) occurs at the spot weld. The difference between the two phase values is used to indicate the thickness (t1) of the wled; whereas the path length over which epsilon min has a constant value is used to indicate the dia. of the spot weld. The pref. appts. includes a sine-wave generator feeding an electronic bridge circuit contg. a phase shifter and phase measuring appts.

Inspecting method and apparatus of projection welding

Abstract: PURPOSE: To judge the goodness or not of the captioned weld zone rapidly and accurately in process by operating the final resistance value of dynamic resistance at the end of current supply and the minimum resistance value of dynamic resistance during current supply period. CONSTITUTION: A suspension lug 14 having projections and a flat plate 16 are pressure-sandwiched by a pair of electrodes 18, 20 and welding current is supplied to the welding works 14, 16 by way of electrodes 18, 20. The outputs of detecting circuits 22, 26 are divided by the 1st arithmetic circuit 28 to obtain the ratio between the output voltage V(t) and output current I(t). The output of the circuit 28 which obtains the dynamic resistance R(t)=V(t)/I(t) between the electrodes 18, 20 is supplied to a final resistance value holding circuit 30 and minimum resistance value holding circuit 32. The resistance R at a desired point is stored in the circuits 30, 32. The final resistance value R 1 and minimum resistance value R 2 of the circuits 30, 32 obtained during current supplying are supplied to a differential amplifier circuit 34 where R 1 -R 2 is operated. In a differential amplifier circuit 38, said value is compared with the reference value R s from a reference voltage setting circuit 40 and only when R 1 -R 2 is smaller than R s , an alarm signal AL is supplied to a display device 42. COPYRIGHT: (C)1980,JPO&Japio

Method and apparatus for spot welding

Abstract: PURPOSE:To simultaneously weld plural points of plural sheets of laminated metallic sheet, and to make stable and good the result, by arranging laminated metallic sheets to be welded between the leg groups, by drilling the through holes in both side faces of these sheets, and by pressing and supplying electricity. CONSTITUTION:In the spot welder 23, the stationary leg group 2 on one side is formed by gathering legs 21, 22, which are supported by the supporter frame 20 so as to be insulated; and the movable leg group 3 on another side is formed by gathering legs 31, 32, which are movably supported by the supporter frame 30 so as to be insulated. The laminated metallic sheet 1 is formed by laminating sheets 11, 12, 13; and the through holes 110, 130, are drilled in the sheet 11 on one side, and in the sheet 13 on another side. The legs 21, 31, and 22, 32, of both leg groups 2, 3, are respectively facing each other interposing the sheet 12; the legs are selectively coupled like as (21, 31), (21, 32) or (32, 31), and are used for the electrodes for supplying the welding power as the conductive material, for welding sheets 12, 13, or 12, 11. As a result, both of weld points 1213, 1112, are welded and fixed to the middle sheet 12.

Watching method for condition of weld at spot welding

Abstract: PURPOSE:To make possible the quality of condition of weld to be judged, by attaching the acoustic emission converter at one of electrodes, and by utilizing the output signal of this converter at the specified moment, for watching the condition of weld at the spot welding CONSTITUTION:The method is constituted as follows; the welding current is supplied from the power source 1 to electrodes 2, 2', until the supply of the previously specified amount of electricity is finished, after that, the AE output, to be produced when the metal solidifies, is detected by the acoustic emission (AE) converter 3 attached to the electrode 2'; this signal is amplified through the preamplifier 4, the filter 5, etc; after the welding is finished, the gate is opened for a specified period of time, and above amplified signal is transmitted to the judging circuit 9 for the quality of weld through the analog gate 7 for catching above signal, and the AE energy circuit 8; the judging circuit 8; the judging circuit 9 judges the quality of weld zone depending on the reference to be settled by the calculation according to the experimental result for the relation between the diameter of weld zone and the AE output, as stated in separate paragraph; and only when the judgement is negative, the alarm 10 is produced As a result, the titled condition of weld can be quantitatively judged at real time

Ultrasonic inspection device of resistance spot welding parts

Abstract: PURPOSE:To make unnecessary the calibration of the relation between the quantity of transmitted ultrasonic wave and the welded part, by regarding the wave reflected twice on the surface of the electrode provided with an ultrasonic vibrator being in contact with the workpiece to be welded as the sensitivity reference, and determining the area of the welded part from the changes in the peak values of the reflected waves. CONSTITUTION:When starting welding, a transmitting circuit 15 sends out ultrasonic waves, and an ultrasonic vibrator 2 receives ultrasonic reflected waves, and the pulse height of the reflected light on a plane of reflection 51 is selected by a receiving circuit 16 and a gate circuit 17, then peak value H1 is detected and held by a detection hold circuit 18. Only when the value H1 is received, a hold circuit 20 holds the output voltage of the circuit 16 at the time of receiving a weld end signal, and outputs peak value H2. The output of difference H2-H1 due to a differential amplifier circuit 21 and echo B2 from the circuit 16 are selected by a gate circuit 22, and fed into an operational circuit 23 to calculate the ratio (H2-H1)/B2, thus obtaining the welding area. Taking the echo B2 as the sensitivity reference, the relation between the quantity of transmitted ultrasonic wave and the welding area is maintained constant, so that it is not necessary to determine the relation between the two at every replacement of electrodes.

Absorberplatine fuer flach-solarkollektoren

Abstract: Arranged on a first corrugated metal sheet (12) is a second corrugated metal sheet (11). The two metal sheets are fastened to one another in the region of their troughs (13) by means of spot welding (17). In the region of each peak (14), the two metal sheets enclose a flow duct (15) for a heat-transfer medium. The thickness of the second metal sheet (11) is smaller than the thickness of the first metal sheet (12). In this manner, the manufacturing price can be kept low although quality material is used.

Method for spot welding galvanized sheet metal

Abstract: The present invention is directed to an improved method and apparatus for effecting spot welds between superimposed sheets of galvanized metal. In accordance with the method, one of the electrodes is comprised of a consumable tip component, preferably a steel ball, whereby predictable and repeatable welding conditions are effected at each welding cycle. The invention is further directed to a method of effecting spot welds between galvanized sheets which includes the step of interposing between a conductive carrier electrode and the metal surface a consumable metallic increment having reduced contact area adapted to engage the galvanized sheet, the consumable component being compatible with the ferrous substrate beneath the galvanized layer.