Showing papers on "Spot welding published in 1989"

Resistance spot welding: a heat transfer study

Abstract: A heat transfer study of resistance spot welding has been conducted both theoretically and experimentally. A numerical solution based on a finite difference formulation of the heat equation has been developed to predict temperature distributions as a function of both time and position during the welding process. The computer model also predicts the temperature distribution through the copper electrodes. One important feature of the program is that it allows for variations in the physical properties of the metal workpiece. Temperature measurements have been made in real and simulated welds of a high-strength low-alloy (HSLA) sheet steel. Excellent agreement is obtained between the numerical solution and the experimental measurements. The heataffected zone (HAZ) obtained by plotting the lines of constant temperature is very similar to that measured from actual welds.

Low-resistance contacts on YBa2Cu3O7−δ ceramics prepared by direct wire bonding methods

Abstract: Wire bonding, such as electric discharge spot welding and ultrasonic bonding, has been investigated for use in simple, conventional methods of preparing low‐resistance ohmic contacts on superconducting Y1 Ba2 Cu3 O7−δ ceramics. Spot welding with thermal annealing improves the contact’s resistivity to 2×10−7 Ω cm2 , while a sample without annealing shows non‐ohmic and semiconductive characteristics. Change in the crystal structure induced by high current is analyzed. Ultrasonic bonding with annealing at 500 °C achieves 3×10−8 Ω cm2 , one of the lowest contact resistivities ever obtained in simple methods. The current‐voltage characteristics show nonlinearity, which is attributed to the superconducting state of the Ag/Y1Ba2Cu3O7−δ interface.

Real time adaptive control for resistance spot welding process

Abstract: This real time adaptive control and method of controlling a spot welding process compensates for electrode wear, oxidized surfaces, fit up variations and machine variations. Workpiece thermal growth is the measurement discriminant and the welding machine heat command is the control input. The control utilizes a least squares estimator to monitor the process and workpiece displacement, a precompensator to shape a desired displacement trajectory command, and a model reference control with a Smith-predictor to compensate for time delays and a proportional-integral-derivative compensator. The model reference control has a mathematical model of the spot welding process and calculates an estimated displacement using a predicated process gain and bias calculated by the estimator. The estimated displacement is compared to the precompensator displacement trajectory and an error is generated which regulates the heat command through the PID compensator.

A Proportional-Integral Controller for Resistance Spot Welding Using Nugget Expansion

Abstract: An electrode wear has been found to cause considerable quality variation in the process of resistance spot welding. This paper presents a study on the electrode wear growth and develops a microprocessor-based feedback controller that can compensate weld quality variation due to electrode deterioration. The controller developed in this study utilizes a PI control algorithm, incorporating the electrode movement as a feedback signal. A series of experiments was performed to clarify the wear growth phenomenon and to evaluate the performance of the controller. The experimental results show that the electrode wear can significantly cause quality deterioration, but this can be effectively compensated via application of this proposed control technique.

Arc spot welding apparatus

Abstract: There is disclosed an arc spot welding apparatus comprising a welding power supplying unit, a wire feeder connected to the welding power supplying unit by a control cable and an arc spot welding torch connected to the wire feeder by a torch cable which is operable by operating an operation switch arranged on a holder thereof to be held by an operator being characterized in that the welding torch comprises ? a nozzle assembly providing a nozzle and a power supply element, a torch holder assembly and a torch body assembly connecting said nozzle assembly and said torch holder assembly which is formed to have a length so that the operator can operate said welding torch from a standing position.

Measurement of Transient Temperature Response during Resistance Spot Welding High-speed cinematography and infrared emission monitoring are used to evaluate heat transfer with various electrodes

Abstract: The transient temperature response during resistance spot welding was measured as a function of various process parameters. The variables include the electrode face thickness, coolant flow rate, welding schedule, elec­ trode force and type of zinc coating. Two different experimental methods were used. The first one used an infrared emission monitoring method which mea­ sures the surface temperature using a Thermovision system. The other method used high-speed cinematography of a cross-sectioned welding setup. The cross-sectioned surface was painted with thermosensitive paint in order to mea­ sure the movement of the isotherm dur­ ing the welding process. It was found that the slowest step of heat transfer during the axial direction in resistance spot welding is convective heat transfer to the coolant at the elec­ trode/coolant interface. There exists a

Dent puller and method of use

Abstract: Apparatus and a method of using it to straighten a dent in a sheet metal workpiece are provided. The apparatus includes a stud welding gun to releasably grip a stud and weld it to the dent, as well as integral hammer means to apply force to the welded stud, straightening the dent. The apparatus and the method of use then provide means for dewelding the stud from the straightened workpiece, thereby avoiding the usual stud cutting and grinding operations. Exchangeable electrodes are provided so that the apparatus can be used for both stud welding and spot welding.

Electrode for resistance welding

Abstract: PURPOSE:To obtain an electrode for spot welding having the high number of spots without electrode deposition and cracking by forming the electrode of triple structure of core material, inner material and sheath material and laminating electric conductivity and vickers hardness of each material and specifying a ratio of a diameter to an outside diameter thereof. CONSTITUTION:The electrode used for spot welding is constituted of the triple structure of the core material 1, the inner material 2 and the sheath material 3 in order in the direction of the outside from the central axis of the electrode. The core material 1 has >=20% electric conductivity IACS (%) and vickers hardness in the range of 130-200 and the inner material 2 has >=70% electric conductivity and vickers hardness in the range of 90-160 and the difference in hardness between the core material 1 and the inner material 2 is made to >=30. Further, the sheath material 3 has >=40% electric conductivity and vickers hardness in the range of 130-200. When the diameter of the core material 1, the outside diameter of the inner material 2 and the outside diameter of the sheath material 3 are denoted by d1, d2 and d3 respectively, the ratio of respective parts is made in the range of d1/d3=0.12-0.32 and constitution is arranged so as to be in the range of d2/d3=0.5-0.75.

Acoustic Emission And Its Application To Laser Spot Welding

Abstract: A simple method for noncontact measuring acoustic emission generated during laser welding of steel X5CrNi18 9 and pure aluminium is presented. Laser beam quality is kept constant to insure that AE signal is just affected by the weld process. It will be shown that measuring in noncontact manner depends on formation of plasma, otherwise AE is generated due to backscattered laser radiation, which heat the fixture of the AE sensor.

Method for monitoring abnormality of spot welding electrode

Abstract: PURPOSE:To always monitor a state of an electrode and to prevent defective welding by measuring repeatedly the length of the electrode wearing away by spot welding and deciding it to be abnormal when variation for every measurement or its accumulated variations exceed a reference value to regrind the electrode. CONSTITUTION:In order to measure the variation of the length of the electrode wearing away, a photoelectric displacement gage 6 to measure a stroke (l) of a cylinder 5 to move the electrode 1 vertically is provided. In addition, the variation of the electrode 1 can be measured as the change of an electric current by providing a coil 7. The length of the electrode 1 wearing away by the spot welding is then measured repeatedly and it is decided to be abnormal when the variation for every measurement or its accumulated variations exceed the reference value and after the abnormality is outputted to a welding controller, the abnormality recovery is processed. The electrode grinding by manual operation or automatic electrode grinding is performed as the abnormality recovery processing.

Convertible single or double spot welding machine

Abstract: A convertible single or double spot welding machine operating by the electrical resistance method for producing grids or bar grates by single spot welding or double spot welding, has a transverse row of electrodes and at least one welding transformer on one side of the welding plane. Electrically conductive connections, which pass through the welding plane, connect the welding transformer to the electrodes located on the other side of the welding plane and close the welding current circuit for single spot welding. In order to convert from single spot welding to double spot welding, the connections which pass through the welding plane are removed, selected electrodes on the side of the welding plane remote from the welding transformer are connected in pairs by current bridges, and the supply lines from the welding transformer are respectively connected to the two electrodes opposite the electrodes connected by the current bridges.

Spot welding condition automatic setting device

Abstract: PURPOSE:To perform inspection with high reliability and to automatically and efficiently set welding conditions based on an inspected result at the time of inspecting by correcting and holding the welding conditions set corresponding to input of the data on materials to be welded according to actual results of welding operation CONSTITUTION:When the data are inputted by a data input means 7 of materials to be welded, a memory control means 10 retrieves whether or not the corresponding welding condition data are stored in a memory 8 as the corrected welding condition data The corrected welding condition data, when the welding condition data is stored, and the reference welding condition data, when the welding condition data is not stored, are outputted respectively to a pressurizer 3 and a welding current control means 4 A monitoring current is applied right after a welding current is applied by the control means 4 and a resistance parameter calculation means 5 calculates a resistance parameter and a welding condition judgement means 6 judges whether or not the deviation is within a tolerance When a judges result is OK, operation is finished as it is and when it is NG, a corrected welding condition data preparing means 9 prepares the correct welding condition data and welding operation is again carried out and when it is OK, the corrected data are stored in the memory 8

Plated steel sheet excellent in spot weldability

Abstract: PURPOSE:To prevent the damage of electrode tip by welding and to improve spot weldability by forming a galvanizing layer on the surface of a steel sheet and then forming a layer of the oxide of Zn and Fe in which coating weight is specified on the above. CONSTITUTION:A single or multilayered plating layer of zinc or alloyed zinc is formed as lower layer on the surface of a steel sheet. Further, an oxide layer consisting of Zn, Fe, and O is formed in a coating weight of 0.005-3.0g/m by the total weight of Zn and Fe on the above. It is preferable that the basic composition of the oxide is ZnFe2O or ZnFeO3. Since the oxide layer has a function of preventing the selective alloying of copper and zinc, the wear of an electrode tip can be retarded. By this method, the number of continuous spot welding can be increased in spot welding, and further, welding can be continued for a long period without changing a tip.

Press device having welding gun

Abstract: PURPOSE:To simultaneously execute press forming of a stock and spot welding, and to curtail the number of processes by containing a pair of welding guns in opposed positions in the upper die and the lower die, and also, providing an energizing means for generating pressing force in the welding gun. CONSTITUTION:When a press device is operated, stocks 5, 6 are inserted and held from the upper and the lower parts by an upper die blank holder part 2b and a blank holding part 3b. In this case, the tip part of each welding gun in welding gun devices 9... of the upper side die blank holder part is pressed against the stock 5 by energizing of a coil spring, and on the other hand, the tip part of each welding gun in welding gun devices 10... of the blank holding part is pressed against the stock 6 by energizing the coil spring. Subsequently, an upper side punch part 2a and the upper die blank holder part descend and drawing of the stocks 5, 6 is executed, and at this time, by allowing a current to flow between the welding guns 9... and 10..., spot welding is executed. Thereafter, the upper die punch 2a and the upper die blank holder part are allowed to ascend in this order, and a formed part is obtained.

Power control and line voltage monitor/compensator for resistance spot welding machines

Abstract: A programmable power control (68) and line voltage monitoring/compensation system (101) for resistance spot welding machines of varying configurations provides maximum time for computer calculation of SCR triggering times and compensates in real time for these input power line fluctuations that affect the welding operation. The power control (68) employs a single programmable delay element (86, 88) the delay time of which is set while the delay is timing out to generate SCR trigger pulses. The commutation effect in three phase welding machine configurations is taken into account by the power control (68) in determining trigger times. The line monitor (101) synthesizes replica signals of both the primary voltage and current transmitted by the SCRs and processes these replica signals to provide various circuit parameters which can be used as feedback to compensate for only those line variations which affect the welding process.

Local strain approach to predict fatigue strength of spot-welded structures.

Abstract: A local strain approach has been studied to predict the fatigue strength of spot welds on thin steel structural members under bending. The strains on the inner and outer surfaces of the sheet near a nugget, where a fatigue crack would appear, were measured. The results showed that the strain on the inner surface is greater than that on the outer surface, and that the position of the sheet is under the combined load of an axial force and a bending moment. The fatigue tests of smooth specimens were performed under the same load condition as the position of sheet on the member using a developed combined loading system. It was confirmed by comparison of Δe-Nf diagrams that the strength of smooth specimens under the combined load makes an accurate prediction of the strength of spot-welded members in terms of the local strain.

Method and equipment for resistance welding

Abstract: PURPOSE: To perform a resistance welding with high continuous spot properties on plated steel sheets by tilting intermittently the central axes of electrode parts in opposition with respect to a pressing axis, further, rotating electrode chips intermittently around the electrode central axes and then, performing welding. CONSTITUTION: A couple of electrode parts in opposition consisting of the electrode chips 1 and 2, and shanks 3 and 4 press and energize materials S to be welded for a prescribed time to perform welding. In the subject resistance spot welding method, both or one of the electrode central axes 11 and 12 of the above-mentioned electrode parts are tilted intermittently by a prescribed angle θ with respect to the pressing axis 10. The electrode chips 1 and 2 are further rotated intermittently by a prescribed angle α with the electrode central axes 11 and 12 as rotation axes. Afterward, the above-mentioned welding is performed. The tip faces of the electrode chips 1 and 2 can be used all over by the above-mentioned tilting and rotation. By this method, when the materials S to be welded are the plated steel sheets, electrode deposition is also prevented and the number of continuous spots is increased and productive efficiency is improved. COPYRIGHT: (C)1990,JPO&Japio

Composite metal plate excellent in vibration-damping property and heat resistance

Abstract: PURPOSE:To reduce the temperature-dependent property of vibration-damping characteristic and at the same time withstands the use in high temperature region and improve the vibration- damping property and heat resistance of a plate by a method wherein metal plates, which have nearly the same thickness as each other and the opposing surfaces of which are roughened mechanically or chemically and, after that, piled up so as to face to each other, are joined together by spot-welding at a plurality of positions. CONSTITUTION:Two metal plates 10 and 10 having the size of 140X60mm are cut out of an SS 41 steel plate with the thickness of 3mm, for example. The surface of each plate is processed with a grinder so as to be roughened to the surface roughness of 100 S. The two piled-up metal plates 10 and 10 are joined together by spot-welding the periphery of the plats at six positions 12 and 12 with electrodes, the size of each of which is 5mm. The surface of the metal plate to be joined is roughened and its preferable surface roughness is in the range of 50-200 S. The preferable diameter of the electrode tip of spot welding is 3-8mm. The preferable number of welding position per unit area is from five to twelve positions per 100cm . Vibrations interfere with each other at the contact surfaces of the metal plates, resulting in consuming vibrational energy in the form of frictional energy and consequently developing vibration-damping effect.

Zinc-plated steel sheet with excellent spot weldability

Abstract: PURPOSE: To improve spot weldability without affecting a harmful influence on characteristics required for a zinc-plated steel sheet by providing a rust-proof oil layer contg. a specified amt. of a silane coupling agent on the surface of the steel sheet. CONSTITUTION: For the title zinc-plated steel sheet, a rust-proof oil layer contg. 0.05-50wt.% silane coupling agent is provided on the surface of the steel sheet. In the rust-proof oil layer, when the amt. of the silane coupling agent is less than 0.05wt.%, an effect improving a life of a chip is less in comparison with the case where only a rust-proof oil layer is provided on the surface of the steel sheet and on the contrary, when the amt. exceeds 50wt.%, a rust-proof ability which the rust-proof oil layer originally has decreases. A suitable amt. of coating of the surface of the steel sheet with such a rust-proof oil layer depends on a pressure applied on a chip when a spot welding is performed and it is ordinary pref. that the amt. is 0.1g/m 2 or larger. However, as the effect is saturated even if too excess atm. is applied on the surface of the steel sheet, it is usually pref. that the amt. is 1g/m 2 or less. COPYRIGHT: (C)1991,JPO&Japio

Investigation and quality control of resistance spot welding

Abstract: (1989). Investigation and quality control of resistance spot welding. Welding International: Vol. 3, No. 12, pp. 1040-1045.

Ultrasonic measurement for nugget geometry of resistance spot.

Abstract: This study proposes a ultrasonic measurement of nugget geometry in resistance spot welding of twoplate lap joint of thin plate below 1 mm in thickness. This measurement is immersion method with point focussed probe and is based on the composite effects of convergence of ultrasonic beam and attenuation due to the multiple reflection. Under the condition which the focus of ultrasonic beam places beneath the backwall, there appears a echo from the backwall within the weld region or from the faying surface with an observable time delay behind the surface echo. Since the time delay of backwall echo is as same as that of interface echo but these two echoes provide different amplitude, the weld region is distinguished from unbonded zones. According to the line scanning, three distinct patterns appear; the flat pattern peculiar to the faying surface, decreasing pattern at the vicinity of nugget boundary and increasing or flat pattern at weld region. The nugget size is determined by the distance between two points changing from the decreasing pattern to increasing or flat one, from which the measurement of nugget size is performed with the accuracy of 0.3 mm. A series of parallel line scanning with aid of personal computer provide the configuration of nugget, which is displayed on the CRT with two methods, that is, colour mode and white-black mode evaluated by the amplitude and gradient of amplitude, respectively.

Spot welding equipment for resin laminating metal plate

Abstract: PURPOSE:To execute a resin exclusion in a short time and to weld without the generation of any cutting by attaching a preheated electrifying electrode in the device welding the title metal plate interposing a resin film between two metal plates by superposing it with other metal plate. CONSTITUTION:Resistance welding is performed by a pair of electrifying electrodes by superposing the laminating metal plate 3 interposing a resin film between two metal plates on the other metal plate. In this device, said electrifying electrode is made a main electrifying electrode 11 and the preheated electrifying electrode 12 which is brought into contact with the back side of the metal plate 3 with which the main electrode 11 is brought into contact is attached independently therefrom. The current passed from the preheated electrifying electrode 12 is passed in an arrow mark direction to the back side of the metal plate 3, the resin 16 just under the main electrode 11 is excluded with its temp. rise in advance, a current is passed between the main electrodes 11 in succession and a melted joining part is formed.

Laser beam spot welding method for gas turbine combustor

Abstract: PURPOSE:To improve strength of weld zones and welding quality by forming a bead pattern of laser beam spot welding into a square spiral shape and performing lap welding of inner cylinder rings and waveform plates adjacent mutually. CONSTITUTION:The inner cylinder rings 1 and the waveform plates 2 being adjacent mutually are pressed via a jig and the laser beam spot weld zones 3 where the prescribed quantities of gaps are held are formed. A laser beam machine is then set to the outsides of the inner cylinder rings 1 and the waveform plates 2 to perform laser beam spot welding on the spot weld zones while being shielded by N2 gas, etc. At this time, the bead pattern of the spot weld zones 3 is formed into the square spiral shape to shift from the center to the outside and laser beam machining is performed. By this method, ring 1 end fitting parts hold large welding areas and are subjected to laser beam spot welding. Accordingly, the need for brazing the weld zones is eliminated and welding strength is improved. Since welding is performed automatically, welding quality is also improved.

Metal base laminate

Abstract: PURPOSE:To restrict the thermal deformation of a metal base plate, and prevent each layer of the metal base plate, a bonded insulating layer, and a metal foil from exfoliating with each other, by using the metal base plate wherein a reinforcing sheet is fixed to a metal plate as a base member and unified in a body, said reinforcing sheet being formed by arranging in parallel two metal band members having mutually different thermal expansion coefficients, and welding the end-portion junction parts, which are unified in a body. CONSTITUTION:By laser beam welding and the like, a first metal band member 5 and a second metal band member 7 are joined in the form of a plane with a metal base plate 4 in which a reinforcing sheet 5 is welded around a metal plate by spot welding and the like. For the first metal band member 6, nickel chromium steel band (thermal expansion coefficient 17X10 ) is used, which is composed of, e.g., 18wt.% chromium, 8wt.% nickel and iron of residual percent. For the second metal band member 7, invar (thermal expansion coefficient 1X10 ) is used, which is composed of, e.g., 36wt.% nickel and 64wt.% iron. On the metal base plate 4, a metal foil 3 is stacked via a bonded insulating layer 2, and subjected to pressing and heating to be formed in a body.

Modeling the effect of surface active elements on weld pool fluid flow, heat transfer and geometry

Abstract: The influence of sulfur on the heat flow and fluid flow and the transient development of the weld pool was quantitatively evaluated for two heats of Type 304 stainless steel containing 90 and 240 ppM sulfur, respectively. A transient heat transfer model was utilized to simulate the heat flow and fluid flow in the weld pool during stationary laser and gas tungsten arc (GTA) spot welds. A recently developed surface tension model was utilized to calculate the temperature coefficient of surface tension (d..gamma../dT) as a function of temperature and sulfur content. This allows a realistic evaluation of the effect of surface-active elements on the fluid flow and weld geometry. The computed results indicate that during stationary welding, the weld pool surface temperatures are fairly high. As a consequence, the temperature coefficient of surface tension becomes negative and a radially outward or a bifurcated flow of weld metal occurs even when the weld pool contains a significant amount of sulfur. The predictions of the model were verified by comparing the calculated and experimentally observed fusion zone geometry. The results indicate very good agreement between the predicted and experimentally observed fusion zone geometry, for both laser and gas tungsten arc (GTA) spotmore » welds, due partly to the accurate treatment of surface tension gradient driven flows. 21 refs., 7 figs., 2 tabs.« less

Method of testing spot-weld connections as well as apparatus for carrying out the method

Abstract: of EP01859861 Method for testing spot-welded joints in which two sheet metal strips are joined to one another by spot-welds positioned in a row and the spot-welds are then tested by peeling, characterized in that the metal sheets are perforated before the peeling in such a way that a hole follows each spot-weld in the direction of testing

Projection for resistance welding and projection welding method

Abstract: PURPOSE: To carry out joining without removing insulating films by bending and working peripheral parts of holes of a first metal plate to the outside so as to roll the insulating films to form projections. CONSTITUTION: The projections 2 for resistance welding are the projections to superpose first and second metal plates 1a and 1b having the insulating films 1c on one sides at least which are subjected to resistance welding. Boring is performed on the first metal plate 1a and the peripheral parts of the holes are bent and worked to the outside so as to roll the insulating films c and the projections 2 are formed so that the bare steel plate surfaces 8 of the hole inside peripheries or the first metal plate surface with which an electrode to energize and pressurize comes into contact are made to an initial contact part with the second metal plate 1b. Accordingly, joining can be carried out without removing the insulating films 1c. COPYRIGHT: (C)1990,JPO&Japio

Ultrasonic examination of resistance spot welds in thin sheet steel using a focusing probe

Abstract: (1989) Ultrasonic examination of resistance spot welds in thin sheet steel using a focusing probe Welding International: Vol 3, No 8, pp 678-683

Energy storaging-type spot welder

Abstract: The utility model discloses an energy storage-type spot welder, which is boosted by a cylinder controlled by a solenoid valve. A full-wave rectification bridge is composed of diodes and controllable silicon in the welding power source circuit, a charge and discharge loop is composed of an electric discharge transformer, an energy storage capacitor and controllable silicon, the electric current flows through the electric discharge transformer in both charging and discharging, the magnetization of the electric discharge transformer can be reduced. A series circuit which is composed of a two-pointer electricity meter with the function of setting the voltage of charging, a magnetic valve coil and an electric relay is connected in parallel with the AC input end of the welding power source circuit. The utility model has the advantages that the speed of charging is high, the magnetization of the electric discharge transformer can be suppressed, and the weld quality can be ensured. In the welding lines of industries of instrumentation and electric appliance, the utility model can be used widely for welding the parts of aluminium, stainless steel, copper, nickle, etc.