Abstract: The thickness of the molten weld nugget is continuously monitored during resistance spot welding, and when proper penetration is achieved the applied current is turned off. An ultrasonic transducer housed in the water cooled lower welding electrode transmits ultrasonic pulses into the workpiece and receives waves reflected at each solid/solid and liquid/solid interface. The position of the latter is tracked by pulse time discrimination of reflected signals; weld nugget penetration is computed using a ratio of times or a pulse time difference.

Abstract: An apparatus for sensing the distance between an object of electrically conductive material and a reference point has an electrode, the tip of which constitutes the reference point. The electrode is connected via a supply line to a high voltage source adapted to generate high voltage pulses to provide an arc between the electrode tip and the object. The apparatus also has an air-cored measuring coil disposed around the supply line for sensing the electric field about the supply line and transmitting to a measuring signal sensing circuit a measuring signal proportional to the electric field. The measuring signal sensing circuit preferably comprises a comparator unit adapted to compare the measuring signal with a signal corresponding to a predetermined distance between the object and the electrode point.

Abstract: A signal emitted from a transducer responsive to the relative power applied during a welding process is enhanced electronically and mathematically to be of use in controlling welder operating parameters and/or in rejecting defective welds. Electronically the signal refined to minimize unnecessary noise in the signal and mathematically the signal is modified and analyzed against a standard. In a high speed welding operation automatic means are necessary to assure weld quality and control welder operation since the rapidity with which the welding takes place is too fast for manual readjustment.

Abstract: The adaptive controller for a resistance spot welder is implemented with a microcomputer and peripherals to handle the monitoring of several process variable inputs and control the welding machine in real time. Before welding power is applied, electrode load, workpiece thickness and dynamic resistance are measured and must fall within predefined limits in order to continue. The workpiece, if necessary, is conditioned to correct fit-up and surface contamination problems by applying power pulses to lower its resistance. The welding power in each half cycle is dynamically adjusted as a function of workpiece thermal expansion and its first derivative to control formation of the weld nugget, and to control the cooling rate and temper the workpiece. During welding the power limits are adjusted in real time to compensate for electrode flattening and shunt effects. The quality of each weld is diagnosed and machine diagnostics are performed.

Abstract: A method is provided for controlling the porosity of a web or film issuing from an electric spark perforating apparatus in accordance with an operator-set reference porosity regardless of variations in web speed, inherent web porosity, spark discharge energy and spark repetition frequency by controlling the frequencies of the electrical sparks applied to the web in accordance with the product of two signals, one a difference signal obtained by comparing the porosity of the web leaving the perforator and the reference porosity and the other signal derived from the speed of the web.

Abstract: A monitoring and control system for use in conjunction with a pulse type welder which utilizes a computer to calculate the impedance characteristics of a weld and compare these characteristics to a preselected set of characteristics to determine if a quality weld has been made. The system then controls the heat and cool time to increase or decrease the tmeperature of the weld and thus control the size of the weld nugget. The monitoring control system is utilized in conjunction with a standard pulse welding control system, which standard system provides a series of heat impulses followed by a series of cool impulses, this cycle being repeated for a preselected number of cycles. The monitoring and control system senses the voltage and current in the welding load and feeds this data to a computer which, in turn, calculates the impedance of the weld.

Abstract: A weld gun mounted on the end of the manipulator arm of a programmable manipulator is repositioned with respect to the initially taught path in accordance with variations in the dimensions of successive workpieces on which a series of spot welds are to be made.A sensing means carried by the weld gun is employed to measure the position of the welding tips relative to the edge of the flanges which are to be welded. The output of this sensing means is employed to reposition the weld gun prior to the next weld. Repositioning may be accomplished by moving the weld gun bodily with respect to the end of the manipulator arm while the manipulator arm remains stationary at the taught position, or by modifying the command signal for the appropriate axis so that the manipulator arm is itself moved to a different position than the initially taught position.

Abstract: A welding apparatus is made capable of avoiding the occurrence of welding wire spattering following a short circuit, for example, by providing an arithmetic circuit having a plurality of selectively operated delay elements which smooth the response to a rapid change in welding conditions.

Abstract: The radiation emitted from a hot weld bead is received by a lens system and ocused onto a first end of a fiber optic light pipe. The received radiation is separated into spectral bands by the use of optical filters, and is then transmitted to one or more photodetectors, each producing a corresponding output signal. The output of each photodetector is compared with a known reference value indicative of an ideal weld. A significant deviation of the output from the reference value indicates the presence of a weld flaw.

Abstract: A floating reference voltage is generated in response to the low frequency components of weld current and is utilized in the control of the width of travel of a welding arc back and forth across a gap to be filled with weld metal. The arc current is integrated during each traverse across the gap and this integral is compared with the floating reference so that as the wall of the gap is approached, the direction of travel of the arc will be reversed. Provision is made for avoidance of the effects of "dip transfer".

Abstract: An arc welding robot control system in which a control console stores the welding conditions upon the completion of a welding cycle. When a suspension of the welding cycle is commanded during its execution, the welding cycle is effected under the stored welding conditions and its robot is stopped at a suspension point. The control console may further include two memories for respectively storing the position of the suspension point and a current and the next position of the robot with coefficients for a linear interpolation. When the welding cycle is restarted after the robot has been displaced from the suspension point to another point, the torch is automatically returned back to the suspension point along a line passed through the two points and points interpolated through calculations of the content of the memories. The torch is moved through taught points and a similarly interpolated point.

Abstract: A method and control circuit for terminating a consumable electrode electric arc welding operation which comprises monitoring the welding parameters of the wire drive motor speed and the arc working voltage, comparing the monitored levels with a multiple number of present combinations of both arc working voltage and motor speed with at least one preset combination defining a high arc working voltage representing a long arc condition and with the last preset combination including a motor speed of relatively close to zero; evaluating each preset combination in tandum to determine if the conditions of a preset combination are satisfied and interrupting the power supplied to the arc in response to the satisfied combination of preset conditions.

Abstract: A DC arc welding apparatus compares the output voltage with an adjustable, preset voltage, and the amplified and integrated difference signal is supplied to a current control circuit together with a current feedback signal. The resulting apparatus operates in a constant voltage mode, thus rendering it applicable to consumable electrode welding. A constant current mode may also be realized, as an alterantive, by bypassing the comparator and feeding the preset voltage directly to the current control circuit.

Abstract: A method and system for controlling resistance welding whereby the preferred quality of resistance welding can be ensured automatically during the welding process by controlling the electrode pressure so that the electrode resistance changes in accordance with a reference resistance curve, or by additionally controlling the electrode voltage so that the electrode voltage changes in accordance with a reference voltage curve. The system according to the present invention comprises an electrode voltage sensor, an electrode current sensor, a reference resistance generator, a reference voltage generator, a differential amplifier, a pressure control device, a current controller and so on.

Abstract: A four-electrode submerged arc welding process employs connections of four electrodes aligned in one row for alternating current source so that electromagnetic force Fx.sub.4 in a direction opposite to a welding direction acting upon a middle point of the arc from the rearmost electrode is within -25.ltorsim.Fx.sub.4 .ltorsim.-10 (N/m). The connections are preferably selected such that phase differences among currents applied to the three electrodes other than the frontmost or rearmost electrode are 120.degree., respectively, and a phase difference of the remaining frontmost or rearmost electrode is within 0.degree..+-.30.degree. relative to the furthermost electrode.With such connections of the four electrodes, the four-electrode submerged arc welding process remarkably prevents welding defects such as undercuts even at higher welding speeds.

Abstract: A method and apparatus for applying filler material to a workpiece in conjunction with a heat producing means, to deposit a heating/molten pool region on the workpiece; wherein the filler wire is introduced into the pool region in a reciprocating manner which alternately advances an end of the filler wire into and out of the pool region; and wherein the heat produced by the heat producing means is varied so that peak heating pulses are initiated and maintained when the filler wire contacts the pool region, and so that the heat producing means maintains a lower, background level when the filler wire is withdrawn from the pool region.

Abstract: A welding method comprises rotating a nozzle (3) provided with a welding electrode (9) eccentrically from the center axial line (a) thereof within a groove (2). The center axial line (a) of the nozzle is aligned with the center of the groove (2) by smoothing values of variation in welding current or welding voltage for each of the left and right half cycles of the nozzle and controllably moving the nozzle horizontally at right angles to the welding direction so that the difference between these values becomes null. The height of the nozzle (3) relative to the groove (2) is maintained at a prescribed distance by smoothing values of variation in welding current or welding voltage and controllably moving vertically the nozzle (3) so that the difference between the thus smoothed value and a set value becomes null.

Abstract: An improved control circuit is disclosed for controlling the arc voltage of welding apparatus. The circuit includes an automatic servo control circuit operative to gradually start the electrode positioning motor in the presence of an error signal indicating that the arc voltage is not at the desired level, to accelerate the motion of the positioning motor until the error signal is nulled and then quickly decelerate the motor to minimize electrode overshoots. The improved circuit is operative to prevent electrode servo "hunting" and results in improved welding operation. Other features and improvements are disclosed.

Abstract: The gap between upper and lower electrodes 1, 2 is measured at constant intervals of time while a contact 5 and a base 6 are pressed by the upper and lower electrodes under a constant pressure. Supply of an electric current to the upper and lower electrodes is controlled upon elapse of a predetermined interval of time after the gap has reached a maximum 18. The amount of metal melted out of a joining interface between the contact 5 and the base 6 is thus quantized to improve and stabilize the quality of joining between the contact 5 and the base 6.

Abstract: Process for the lateral positioning of a member relative to a joint formed between two metal surfaces and having discontinuities and using at least one eddy current probe, wherein the signal supplied by each of the probes are processed to obtain at least one positioning signal varying with the displacement of the axis of the corresponding probe relative to the axis of the joint and at least one signal indicating the presence of a discontinuity and transmitted when the corresponding probe faces a discontinuity of the joint, wherein the member is laterally displaced as a function of variations of the positioning signal and wherein the control of the displacement of said member is interrupted as a function of variations of the positioning signal when a signal indicating the presence of a discontinuity is transmitted.The invention also relates to an apparatus for performing this process.