To provide a spot welding system of high reliability which, when an abnormality such as a spot missing in spot welding occurs, is capable of more precisely and accurately detecting this immediately. Provided are a robot-side system having a robot and a robot-side control unit which controls driving of the robot; and a welder-side system having a welding gun mounted to the robot, and a welder-side control unit, in which the robot-side system includes: a storage unit which stores in advance appropriate thickness information of a welded part of members on which conducting spot welding; a welded-part thickness measurement unit which measures thickness of the welded part of members on which conducting spot welding; and a comparative determination unit which determines quality by comparing thicknesses of a welded part at the time of a welding start command and at the time of a welding completion command, and comparing with the appropriate thickness information of the welded part stored in the storage unit.

A single side heating apparatus, which can make contact portions of electrodes properly contact with a workpiece, is provided. A single side heating apparatus (1) equipped with a pair of electrodes (2A, 2B) for heating a workpiece from one side of the workpiece includes: a base portion (3); the pair of electrodes (2A, 2B) each having a contact portion (4) configured to contact with the workpiece in one direction continuously or at a plurality of spaced-apart portions thereof; an electrode holder (5), to which the pair of electrodes (2A, 2B) are fixed; and a four-bar linkage (7) provided between the base portion (3) and the electrode holder (5) and configured to rotate to tilt the electrode holder (5) around an axis (O1) orthogonal to a direction in which the contact portions (4) extend, by a reaction force received by the electrodes (2A, 2B) from the workpiece, wherein the four-bar linkage (7) includes a first link located closer to the electrode holder (5), a second link located closer to the base portion (3), a third link, and a fourth link, the first link being shorter than the second link, and the third link and the fourth link being equal in length.

An electric resistance spot welding device, comprising a pair of electrodes located on the same welding surface of an assembly to be welded. The assembly to be welded is provided with an axis of symmetry (6); the pair of electrodes are symmetrically disposed on two sides of the axis of symmetry; one end of each electrode has a special-shaped contact surface (20); the special-shaped contact surfaces are respectively offset in directions away from the axis of symmetry relative to the electrode axis, wherein the special-shaped contact surfaces are used for offsetting a current density centerline (21) formed by the electrodes in a direction away from the axis of symmetry relative to the electrode axis (11), and/or used for deflecting the tendency of the current density of each electrode away from a welding face within the assembly to be welded. The device can achieve a symmetrical and uniform shape of distal and proximal ends of a nugget with respect to the axis of symmetry, such that both the shape and stress state of the nugget can meet requirements for mechanical properties under load, thus improving the welding quality. The present application also relates to an electric resistance spot welding method.

An electric resistance spot welding device, comprising a pair of electrodes located on the same welding surface of an assembly to be welded. The assembly to be welded is provided with an axis of symmetry (6); the pair of electrodes are symmetrically disposed on two sides of the axis of symmetry; one end of each electrode has a special-shaped contact surface (20); the special-shaped contact surfaces are respectively offset in directions away from the axis of symmetry relative to the electrode axis, wherein the special-shaped contact surfaces are used for offsetting a current density centerline (21) formed by the electrodes in a direction away from the axis of symmetry relative to the electrode axis (11), and/or used for deflecting the tendency of the current density of each electrode away from a welding face within the assembly to be welded. The device can achieve a symmetrical and uniform shape of distal and proximal ends of a nugget with respect to the axis of symmetry, such that both the shape and stress state of the nugget can meet requirements for mechanical properties under load, thus improving the welding quality. The present application also relates to an electric resistance spot welding method.

A holding part of a welding gun holds a held part that is provided to an arm having resistance welding electrodes. A first facing part and second facing part of the holding part face each other with the held part therebetween, so as to form a layered part. A connecting part fixes the relative positions of the first facing part and the second facing part. A collar is inserted into a through hole of the first facing part so as to be movable in the layering direction. When a pressing mechanism presses the second facing part, the held part, and the collar in the layering direction, the held part is sandwiched between the second facing part and the collar.

A spot welding apparatus includes a stationary frame having a housing formed therein. An upper welding gun is mounted to a length direction of a pressing unit disposed in the housing of the stationary frame. A plurality of lower welding guns are mounted on an outside of the stationary frame and ends of the plurality of lower welding guns selectively face one end of the upper welding gun in a length direction of the lower welding guns by the plurality of lower welding guns. A plurality of actuators are mounted on the outside of the stationary frame. A plurality of link units are disposed between the actuators and the lower welding guns, connect the actuators and the lower welding guns, respectively, and rotate as the actuators are operated.

A spot welding system includes a spot welding gun, a robot, and a tip dresser that polishes a face of electrode. The tip dresser includes a blade that cuts the face of the electrode and a blade driving motor that rotates the blade. A dresser control section of a control device detects torque of the blade driving motor. When the torque of the blade driving motor exceeds a predetermined torque upper limit value, the dresser control section carries out speed reduction control that reduces the rotation speed of the blade driving motor.

A cap dispenser for a welding gun includes a sleeve that slidably receives a drawer that is configured to house a column of weld caps. The cap dispenser also includes a spring that cooperates with a slide block that is arranged in the drawer. The spring urges the slide block toward an aperture in the drawer that is configured to receive a welding gun electrode.

A C-shaped tool holder consisting of an integral frame structure that is delimited by an inner and an outer edge, each C-shaped, in which the C-shaped edges are made from and are connected to each other by at least five multiple-vertex frame bodies that are integrated into the frame structure, in particular triangles, quadrilaterals and pentagons, wherein in each case an inner side of the individual multiple-vertex frame bodies is a connecting surface, continuously curving along a circumferential direction, along the sides of the respective multiple-vertex frame body, and the inner and the outer C-shaped edge is each delimited to the outside by a continuously curving lateral surface.

A vehicle composite member to be joined at a perimeter section to a ferrous vehicle body member is provided. The vehicle composite member includes a lightweight panel that is formed of a lightweight material having a lighter specific weight than iron, and a ferrous perimeter member that has been integrated with the lightweight panel. The perimeter section is configured by the ferrous perimeter member.