Provided is a spot welding machine able to perform spot welding in which the desired nugget size is formed while suppressing spatter even if the strengths or thicknesses of the metal sheets change, the machine comprising: a pair of electrode tips, a pair of pressing members arranged around the tips, a first power supply, first and second drive mechanisms, and a pressing force control part, wherein the tips and the pressing members are respectively arranged facing each other so as to be able to sandwich a set of sheets between them, the first drive mechanisms give pressing forces pressing the tips against the sheets, the second drive mechanisms give pressing forces pressing the pressing members against the sheets, and the control part independently controls the pressing forces given by the first and second drive mechanisms.

A stored time variation curve and cumulative amount of heat generated of each step are each used as a target. In the case where a time variation of an instantaneous amount of heat generated per unit volume differs from the time variation curve in any of the steps, a current passage amount is controlled in order to compensate for the difference within a remaining welding time in the step so that a cumulative amount of heat generated per unit volume in actual welding matches the stored cumulative amount of heat generated in the test welding. Further, in the case where expulsion is detected in any of the steps, then in subsequent welding, the cumulative amount of heat generated per unit volume used as the target is reduced, and the current passage amount is adjusted in accordance with the reduced cumulative amount of heat generated per unit volume.

A welding apparatus includes a module for prompting a user to input a command indicating that a welding pressure between a movable electrode tip and a fixed electrode tip has reached each of two welding pressures, a module for identifying a torque exerted in the servo motor and a movement amount of the movable electrode tip at a point in time when the command is input, a module for deriving a relational expression between the welding pressure and the movement amount, a module for using the relational expression to estimate a movement amount of the movable electrode tip required to generate another welding pressure, and a module for identifying a torque required for the movable electrode tip to move the estimated movement amount, and registering the torque in association with the another welding pressure.

A method for resistance welding includes performing a plurality of resistance welding processes during which welding electrodes are pressed against respective welding spots of respective workpieces. The welding electrodes are energized with a respective welding current for each of the plurality of resistance welding processes, and for each of the plurality of resistance welding processes, a respective at least one characteristic value that characterizes a quality of the welding is determined. A statistical analysis of the determined at least one characteristic value for each of the plurality of resistance welding processes is performed, and based upon the analysis, an adaptation of the prescribed welding parameters is determined.

The disclosure relates to a measuring device (1) for automated welding devices, in particular for robot welding tongs with a housing (18); with a holding piece (19); that is affixed inside the housing (18) and insulated against the housing (18) by means of a first insulating ring (2); that has a reception space (22) with a base wall (23) and an affixing appliance (24); and with a load cell (17) that is affixed inside the housing (18) opposite the base wall (23) and that is insulated against the housing (18) by means of a circumferential second insulating ring (5) and an insulating washer appliance (7, 21) located at the front-face side and adjacent to the base wall (23).

An electronically-controlled electric resistance welding head and method having a support structure and the electrodes located on the same side. The welding head including a ground electrode having an elastic device and a detecting device for detecting a force load on the elastic device on contact with a component to be welded. A welding electrode is movable relative to the ground electrode and the support structure to contact the component to be welded. An electronic control unit is operable to selectively increase the force applied by each electrode when in contact with the component to be welded until respective threshold values are achieved. Current is generated by a transformer for passage to the electrodes.

A strain gauge for a welding gun includes a housing having at least two portions forming a single closed internal shielded space; a sensing element including one or more resistive strain sensors combined into a strain gage bridge; a ground line of the force data output device having a galvanic contact with at least one of the portions of the housing; and a communication line connecting the sensing element with a force data output device and having a damping bend. The sensing element is arranged on an inner surface of one of the portions of the housing, which has a material thinning in the area of the sensing element, between housing supports of the strain gauge that are made of an electrically non-conductive material of high rigidity. The height of the housing supports is such to prevent contact between the housing and a surface of the welding gun.

In the present invention, while a welding current is applied with respect to a laminate body comprising thick metal plates and thin metal plates, a first welding pressure (F1) with respect to the laminate body from an upper tip contacting the metal plate and a second welding pressure (F2) with respect to the laminate body from a lower tip contacting the metal plate are changed relative to each other. Specifically, F1<F2 in a first step which is an initial period of welding, F1=F2 in a second step which is an intermediate period of welding, and F1>F2 in a third step which is a final period of welding.

A power supply unit for a resistance welding apparatus, said power supply unit comprising a converter circuit adapted to convert an alternating power supply current, AC, applied via a residual current protection circuit to an input of said converter circuit into a pulsed electrical current supplied from an output of said converter circuit to a primary coil of a transformer of said resistance welding apparatus, and at least one switching element provided between the output of said converter circuit and protective earth.

An apparatus includes a housing, a lever, a plurality of gears and a sensor. The housing may be configured to receive a weld head. The lever may be rotatably attached to the housing and configured to convert a linear position of a free end of the lever relative to the housing into a first angular position of a first shaft relative to the housing. The gears may be configured to transform the first angular position of the first shaft to a second angular position of a second shaft. The sensor may be coupled to the second shaft and configured to generate a value representative of the linear position of the free end of the lever by a measurement of the second angular position of the second shaft.