Showing papers on "Spot welding published in 1988"

A J-Integral Approach to Fatigue Resistance of a Tensile-Shear Spot Weld

Abstract: A J-integral approach was used in this study to predict the fatigue lives of spot welds subjected to tensile-shear loads. Using a three-dimensional finite element program, J-integral values were computed for spot welds that reflect the overall weld stiffness

Spot-welding nickel-plated metal terminal

Abstract: A nickel-plated metal terminal to be spot welded has a contact part plated with nickel and a spot welding part to be spot welded to a metal part not plated with nickel thereby improving the weld characteristic of the spot welded terminal.

Method of producing a corrosion-resistant joint between metallic structural elements by spot welding

Abstract: Method of producing a corrosion-resistant joint between metallic structural elements by spot welding, the method being characterised by the steps: - pretreatment of the joining surfaces (4', 5') for - the spot-welding operation, and - the adhesive application of anti-corrosive layers (8), as well as - degreasing, - rinsing - pickling, - application of a layer (8) of sealing compound at least on one side to the joining surfaces (4, 5) of one of the structural elements (4, 5), - tacking of the structural elements (4, 5), - spot-welding operation with - setting of a defined electrode pressure for obtaining metallically bright joining-surface sections in the area of the electrode pressure point (10), - current supply for producing the weld spot (11), and - hardening of the sealing compound (8).

Manufacture of steel plate coated with fused alloyed zinc by galuanization excellent in spot weldability

Abstract: PURPOSE: To improve the peeling resistance of plating and continuous spot welding characteristic at the time of spot welding by annealing a cold rolled steel plate with a specific composition and subjecting this steel sheet to coating with fuzed zinc in an Al-containing hot dip galvanizing bath and then to alloying treatment by heating so as to specify Fe content in a plating layer. CONSTITUTION: In continuous hot dip galvanizing equipment, a cold rolled steel plate containing ≤0.005% C, 0.005-0.05% Ti, 0.01-0.1% Al, 0.005-0.015% Nb, and 0.0002-0.002% B is annealed at 770-900°C and cooled at ≥10°C/sec cooling rate. Subsequently, the above steel plate is dipped into a hot dip galvanizing bath containing ≥13% Al to undergo galvanizing and is then subjected to alloying treatment by heating, by which Fe content in a plating layer is regulated to 9-12%. By this method, a steel plate coated with fused alloyed zinc by galvanization in which powdering characteristic at the time of press forming is controlled and which has superior continuous spot welding characteristic at the time of spot welding can be obtained. COPYRIGHT: (C)1990,JPO&Japio

Parametric analysis of resistance spot welding lobe curve

Abstract: A linearized lumped parameter heat balance model was developed and is discussed for the general case of resistance welding to see the effects of each parameter on the lobe shape. The parameters include material properties, geometry of electrodes and work piece, weld time and current, and electrical and thermal contact characteristics. These are then related to heat dissipation in the electrodes and the work piece

Rotative tool for repairing electrodes for spot welding

Abstract: In a spot welding to effect welding overlaid metal plates clamped by two opposite electrodes to which greater current is applied, tips of the electrodes are frustoconically shaped. Rotative tool (1) having recesses (H, J) respectively of reverse frustoconical shapes is provided with edged portions of notched portions formed by notching radially the peripheral wall thereof and through holes provided at the notched portions. Cut powder generated when the electrodes are cut is dropped off downward from the through holes. Tip ends on ceiling surfaces of the electrodes are cut at the same time by edged portion formed at upper edges (3) provided at the diameter of an extended portion (61) formed by extending over perforated bottoms of the recesses.

Mask-frame assembly and method of manufacturing the same

Abstract: The invention relates to a mask-frame assembly for use as a color-selecting-electrode system in a color-television tube. The structure features of the mask allow for a simplified method of manufacturing such an assembly. The mask and frame are subjected to a common surface treatment in accordance with a particular temperature program after joining them together at given points by spot welding.

Method of automatically grinding an electrode for spot welding use and apparatus for effecting said method

Abstract: An apparatus for successively automatically grinding a plurality of welding electrodes of respective spot welding machines is provided with a stand transported by a work transport conveyor of a welding line, at least one automatic dresser properly positioned on the stand and a pair of through-openings formed in the stand for properly positioning the stand with respect to a work receiving jig on which the stand is placed. The stand is initially placed on a hanger of the conveyor and transported to one of a plurality of work stations by the conveyor. At the work station, the stand is properly positioned with respect to and placed on the work receiving jig. The welding electrode of the spot welding machine located at this work station is then automatically ground by the automatic dresser. Upon completion of grinding at this work station, the stand is further transported to the adjoining work station. In this way, the welding electrodes of all the spot welding machines are successively automatically ground by the automatic dresser.

Effect of spot weld distribution characteristics on the fatigue strength of resistance welded joints

Abstract: Resistance spot-welded joints are often the Achilles heel of structures subject to fatigue stresses. Although many papers, applying both numerical and experimental techniques, have been published in the last few years, the problem of correlation between joint design and fatigue strength has not yet been satisfactorily resolved. The aim of this article is to identify such a correlation for simple lap joints, to provide designers with a useful tool allowing them to evaluate easily and quickly the improved fatigue strength obtainable by changing the number of weld spots.

Current-loop feedback of spot welding machines

Abstract: To control the welding current in a resistance spot welding system, a current measurement sensor is used with a current feedback control to vary the firing angle of power devices in the primary side of the power supply. The closed-loop feedback control assures the desired current is applied independent of variations in the resistance of the welding equipment and primary line voltage variations. In the current feedback control, the commanded current, proportional error, integral error and line voltage offset are summed to derive the firing angle signal, and the power supply is adjusted until actual current equals the desired current.

Apparatus for reprocessing spot welding electrodes

Abstract: In apparatus according to the present invention, re-forming takes place in a single operation. The forming device contains a die extended by a hollow cylindrical die area and includes a punch which is surrounded by an outer punch which is advanced under the tension of a spring and fits into the hollow cylindrical die area. A conical centering area is located upstream of the hollow cylindrical die area. Used spot welding electrodes of different lengths and pronounced deformation can be restored several times with this forming tool.

Organic electrolytic battery

Abstract: PURPOSE:To reduce the electric resistance at a lead plate part and to improve the safety by using a stainless steel furnishing a specific coverage layer which consists of aluminum or an aluminum alloy at the surface of the inner side of a battery as the material of a sealing cap, and connecting the lead plate on the coverage layer of the sealing cap by a spot welding. CONSTITUTION:As a lead plate 3 led out from a collector of a positive electrode plate, aluminum or an aluminum alloy is used, and as the material of a sealing cap 4 welded to the lead plate 3, a stainless steel 5a furnishing a coverage layer 5b which consists of aluminum or an aluminum alloy with the thickness 0.03mm at least, and being 35% of the thickness of the sealing cap 4 at the inner side of the battery at the maximum, is used. The lead plate 3 is welded and connected on the coverage layer 5b of the sealing cap 4 by a spit welding. As a result, an aluminum type lead plate of a low electric resistance can be adoped without reducing the welding strength and the battery assembly workability, and when the battery is short-circuit to an external unit, a burning or a breaking of the battery owing to an abnormal heating can be prevented.

Infrared Signature Analysis: Real Time Monitoring Of Manufacturing Processes

Abstract: The ability to monitor manufacturing processes in an adaptive control mode and perform an inspection in real time is of interest to fabricators in the pressure vessel, aerospace, automotive, nuclear and shipbuilding industries. Results of a series of experiments using infrared thermography as the principal sensing mode are presented to show how artificial intelligence contained in infrared isotherm, contains vast critical process variables. Image processing computer software development has demonstrated in a spot welding application how the process can be monitored and controlled in real time. The IR vision sensor program is now under way. Research thus far has focused on fusion welding, resistance spot welding and metal removal.

Basic phenomena in resistance spot welding

Abstract: Improvement in resistance spot welding quality in sheet metal do have significant implications on the automotive manufacturing process. This paper reports on our recent effect to gain a fundamental understanding of the weld development process. A simple physical model, based on the dynamic resistance curve is presented describing the resistance changes during the process of weld development

Method and apparatus for spot weld control

Abstract: Ultrasonic transducers (28) spring biased (36) into seating engagement in a pair of opposed spot welding tips (24) transmit and receive ultrasonic waves and associated circuitry (16,18) measures the time of flight between the transducers which is a function of tip separation, workpiece temperature and weld nugget size which are indicators of the progress of a weld. The rate of change of flight time is measured and the weld current is adjusted early in the weld cycle to maintain a preset rate of weld growth. The weld current is terminated later in the cycle if the transit time rate falls below another preset value. Otherwise the weld current and termination time follow a standard schedule.

Lap welding method

Abstract: PURPOSE:To weld both metal plates to the satisfactory surface without deviation of the metal plates and a welding dent by forming a weld recessed zone lapping the metal plate of the other side on a bent part with different levels of the metal plate and spot-welding the abutting end face of the metal plate of the other side and afterward, overlay-welding the weld recessed zone CONSTITUTION:The metal plate 2 of the other side is lapped on the bent part with the different levels of the metal plate 1 to form the weld recessed zone 3 The abutting end face 2a part of the metal plate 2 of the other side is subjected to the indirect spot welding 6 to join both the metal plates Next, the weld recessed zone 3 is overlay-welded 11 to make it to the gentle surface Both the metal plates 1 and 2 are welded without the deviation of the metal plates and the welding dent and made in the satisfactory surface condition Furthermore, if this overlay part is smoothened by a grinder, etc, the finishing is improved much more

Spot welding method for laminated steel plate

Abstract: PURPOSE:To prevent the expansion of a steel plate with the expansion of a resin layer at spot welding time by electrifying the joining part surrounded by a pressing member with pressurizing it by a welding electrode in the state of pressing the periphery of the joining part of a laminated steel plate by a cylindrical pressing member CONSTITUTION:The laminated steel plate 1 made by laminating two sheets of skin steel plates 1A, 1C by pinching a resin layer 1B therein is subjected to a spot welding by overlapping the laminated steel plate 1 each other or it with an ordinary steel plate 2 In this case, the joining part surrounded by insulating cylindrical pressing members 5, 6 is electrified by pressing it with welding electrodes 3, 4 in the state of pressing by the members 5, 6 the periphery of the joining part of the overlapped steel plates 1, 2 The problem that the laminated steel plate is expanded with the expansion of the resin layer at the spot welding time can thus be eliminated

Manufacture of hollow metal panel

Abstract: PURPOSE: To surely weld interior materials to side plates by forming projection for spot welding and auxiliary projections on the interior materials and performing spot welding on the positions corresponding to the projections for spot welding by electrodes via both side plates. CONSTITUTION: The interior materials 4 and 5 are mounted on one side plate 2 and the other side plate 3 is mounted thereon and the positions corresponding to the projections 6 for spot welding are held between the upper and lower electrodes 10 via both side plates 2 and 3 and electrified and the projections 6 and the side plates 2 and 3 are welded together. This operation is carried out successively on the projections 6 for spot welding corresponding to each other up and down and the interior material 4 is integrated with both side plates 2 and 3. The auxiliary projections 7 comes in contact with the upper and lower side plates 2 and 3 and carryout a tripping function and prevent inclination and in addition, these are positioned outside the regions pressed by the electrodes 10, hence these parts are not welded. The operation is also carried out on the interior material 5 in the same way, by which the whole is integrated. COPYRIGHT: (C)1989,JPO&Japio

Process for joining work pieces by resistance heating with a short-time energy pulse

Abstract: Particularly in resistance spot welding or resistance soldering of a contact to a support, e.g. a miniature contact to a contact spring, the process described leads to a minimisation of the contact hardness losses during the process by introducing a short-time energy pulse. Further advantages consist in a reduction in the damage to the surface of the contact material, the increasing of the strength of the joint zone, greater uniformity within the joint zone and the lengthening of the electrode life by three to five times as well as an extremely small transfer of copper from the electrode to the contact surface, the said transfer being at the limit of detectability. In the process, a contact element, e.g. made of silver, is welded to a contact support by means of a welding aid, e.g. composed of Cu Ni 30 Fe or by means of a brazing solder, e.g. composed of L Ag 15 P5, or by means of carrier material and brazing solder, or is connected to the said contact support by flux-free brazing. In order to achieve the abovementioned advantages, the energy pulse used in the process is an extremely steep-flanked controlled energy pulse which at the same time has a high current intensity. This results in rapid introduction into the joint zone of the energy required for joining, unnecessary heating, associated with power loss, of the areas of the material adjacent to the joint zone being eliminated at the same time.

Electrodes for use in spot welding

Abstract: Electrodes for use in spot welding which can spot-weld a metallic material having a large electric conductivity and a large thermal conductivity with a small electric current. A cup-shaped cap made of material having a small electric conductivity, a small thermal conductivity and a high melting point temperature as compared to the material to be welded, for instance, made of titanium, is fitted arond a tip end portion of an electrode main body. The top surface of the cap is formed in a spherical shape having a large radius of curvature, and a depression is formed at the central portion of the top surface. The thickness of the top wall is thick at the central portion and thin at the peripheral portion. Plating of soft metal having a better thermal conductivity than the electrode main body is applied onto the entire inner surface of the cap coming into contact with the electrode main body. At least between the top wall of the cap and the tip end surface of the electrode main body, is interposed a plate member made of metal having a better electric conductivity than the electrode main body and a good thermal conductivity and a small hardness as compared to the cap. At least the top surface of the cap is subjected to nitriding treatment.

Welding method for automobile body

Abstract: PURPOSE:To reduce the size of welding equipment for tacking and to maintain high accuracy of an assembled automobile body by forming a nugget with a smaller diameter than that of the nugget of a work by the additional spot welding. CONSTITUTION:A cylinder 34 is pressed by air with panel parts P to be welded between and a copper plate of a feeding terminal 32 is pressed and held by the electrode tip of a gun 40 for feeding. The small nugget to the extent that the tack-welding strength is obtained by a welding current supplied through a secondary cable 33 is formed to a weld zone and the respective panel parts P are tacked. Then, when welding places are moved in order and when the predetermined necessary number of spots of the spot welding is completed, the welding work is stopped and respective fixtures 21 and 22, etc., to hold the respective panel parts P in-between are released. The tack-welded automobile body is mounted on a shuttle bar 17 and moved to an additional spotting stage and the additional spot welding is performed to form the automobile body with the sufficient assembled strength.

Relation between the total fatigue life and the fatigue crack initation life of a spot weld.

Abstract: The relation between the total fatigue life and the fatigue crack initiation life of a single spot weld tensile shear specimen was determined. Based on the results, the reason why the initial stress intensity factor could control the toota fatigue life was discussed. During the investigation, the methods of determination of fatigue crack initiation at the spot weld were developed, and related phenomena were elocidated.

Multiple spot welding robot

Abstract: PURPOSE:To simultaneously weld with pressurization respective weld zones by arranging plural gun mounting plates movable in the triaxial direction at least to a mechanical frame for upper electrodes just above or just beside a lower electrode stand on which all electrodes for the multiple spot welding are arranged and moving the respective gun mounting plates to the welding positions by the storage. CONSTITUTION:When a product W is mounted on a prescribed lower electrode E, the welding position is brought into close contact with the upper surface of the electrode E. Next, when a kind is designated to an integrated controller, the three gun mounting plates 11 move by the prescribed distance vertically and horizontally from the reference position individually as taught in advance by respective servomotors 15 and 19 arranged to the mechanical frame 10 for the upper electrodes. Next, when the gun mounting plates 11 come just above the prescribed positions respectively, solenoid valves of air cylinders are opened and the mounting plates 11 and guns G descend. Then, a necessary one of the three guns G of the respective mounting plates 11 stops mounting the upper electrode E' on the welding position of the product W. Next, after the air cylinder is made to generate the internal pressure corresponding to the welding pressure, the welding operation is instructed to each gun G to finish the entire welding by providing the pressure and electrification.

Spot welding machine

Abstract: PURPOSE:To weld a terminal, etc., without executing special prerepair on the conductive wire coated with the heat resistant synthetic resin of an esterimido, etc., by setting the electric resistant value of 1st and 3rd electrodes at higher value than that of a 2nd electrode. CONSTITUTION:The conductive wire 42 coated with the synthetic resin film 42b to be removed by melting with heating, for instance, and the terminal member 44 to connect it are superposed between the 1st electrode 20, 3rd electrode 22 and the 2nd electrode 21 to pinch it. With starting of electrification thereafter, a current is first passed through the route of the 3rd electrode 22 from the 1st electrode 20 by being blocked by the synthetic resin coating film 42b. At this time, the 1st electrode 20 and 3rd electrode 22 having high electric resistant value become in high temp. instantaneously with heat generation to melt the synthetic resin film 42b. With this melting, the electric insulation is destroyed and the current is passed toward the 3rd electrode 22 from the 1st electrode 20 to enable work welding.

Arc spot welding control device

Abstract: PURPOSE:To prevent the defect in welding by comparing the welding current cutoff time by a welding current cutoff detector with the preset reference time by a reference time setter and placing a command to a spot sequence circuit once again for the cutoff of the welding current continuing more than a fixed time. CONSTITUTION:In case of a welding current being cut while under welding a welding current cutoff detector 3 inputs its detection output to a time counter 9. The set output of a reference time setter 8 is simultaneously inputted to this counter 9 as well and this set time and welding current cut time are compared. In case the welding current cutoff time exceeds the above set time the counter 9 transmits an output, inputting to a repeat command circuit 10. As a result, the circuit 10 gives a command to a spot sequence circuit 1 so as to repeat the arc spot welding once again after a fixed time after completing the arc spot welding once. A welding power source 2 is then transmits its output again to automatically perform the arc spot welding onto the same place.

Laser spot welding method

Abstract: PURPOSE:To reduce the charging energy and to restrain the deformation by piercing a hole using a laser beam before welding in the case of performing the lap welding using the same laser beam. CONSTITUTION:Oxygen gas is led from an assisting gas introduction port 20 and the oxygen gas is blown against an object 7 to be welded together with the laser beam 1 and the hole 30 is pierced in the object 7 to be welded. Next, argon gas is led from an assisting gas introduction port 21 and blown against the object 7 to be welded and the laser beam is projected thereon while shielding it. Since the laser beam 1 enters the hole 30 and is absorbed from the side of the hole 30, the spot welding can be effectively performed. Moreover, the volume of a weld zone is reduced and further, the difference between the joining part diameter and the melting diameter of the surface is reduced and the stable welding with little deformation can be performed.

Ultrasonic examination for resistance spot welds of thin sheet steel with focusing probe

Abstract: It is generally impossible to non-destructively inspect spot welds of thin materials by the conventional normal beam technique of ultrasonic testing, because surface and flaw echoes appear so near together on the cathode-ray tube that these echoes can not be distinguished from each other. In this paper, the nugget formation in resistance spot welding of two-plate lap joints of 0.5 mm thick mild steel sheet is examined micrographically, and an improved technique of ultrasonic testing with an immersion-type focusing probe is tried to evaluate the welds. As a result of this study, the welding variables to produce sound fusion or solid-state welds without expulsion during welding process are determined. In the present ultrasonic technique under such a water distance, that the focus of ultrasonic beam locates beneath the weldment, the echoes from back reflection within the weld region and from faying surface reflection within the nonwelded region converge by multiple reflection, and the echo peak appears with an observable delay behind the front surface echo on the A-scan display. By this process, the back and interface echoes can be detected on the scanning inspection too. The scanning graph of the echo height of back and interface reflections versus probe location for each weld mostly records a composite pattern of protrusion and depression from the level of interface echo due to convergence of the back echo and scattering of wave by the indentation of surface respectively. The C-scan display drawn from these scanning graphs indicates shape of the weld region and data corresponding to the indentation.