Abstract: An electric motor device for powering a tool clamp, for example a resistance welding clamp, of the type comprising a casing of an electric motor 4 the shaft of which is connected to the clamp, to control the electrodes for opening, closing and clamping them onto a metal sheet, by a system of the through-the-motor type which converts the rotary motion of the shaft into translational motion of a mechanism 5 operating the clamp, this motor being linked to a control variator and a slaving device 10 coupled to the rotor of the motor. The device 10 being arranged at the end of the motor shaft, the shaft is fitted with a gear wheel 14 which can be operated from the outside, for rotating it manually, through at least one opening 15 in the casing offset with respect to the motor shaft.

Abstract: The invention concerns an actuator (21) comprising a pre-stroke rod (29) which can be fixed to the tool body, for example soldering pliers. Thus by pressurising the pre-stroke chamber (27) the working rod (34) for closing the pliers can be brought into an intermediate small opening position, the working piston (31) and the amplifying pistons (36 and 37) remaining retracted in the actuator. Since the rod (29) can then be locked relative to the actuator body (21), pressurisation of the working chamber (32) and the amplifying chambers (38 and 40) will then cause the working rod to be extracted (34) and the soldering pliers to be closed without any recoil from the actuator body.

Abstract: The electrode holder comprises a body 1 suspended by an articulated link 9, 13, 14 from a sling 6, this articulated link comprising a pivot collar 13 in which the body can rotate around a principal longitudinal, swiveling axis X and a pivot 14 mounted on this collar and by means of which the body 1 can pivot on the end of the sling 6 around a horizontal lateral axis y perpendicular to axis X. The body 1 is integral with an inclinometer giving the value and sense of the angle of pivot of the body around the principal axis X, and of the lateral axis y in relation to a reference vertical. This information is used to identify the welding location and to automatically select the appropriate welding sequence corresponding to this location. This sequence is coded and transferred to a welding control cabinet to be executed.

Abstract: A method of electrically welding a part such as a bolt around a bore of a composite sheet comprising an intermediate layer of a substantially insulating material disposed between two metal layers. Said sheet is pre-heated in the vicinity of said bore in order to remove said substantially insulating material therefrom, after which said part is welded onto said sheet by a conventional resistance spot welding method. Preferably, said pre-heating operation is conducted by passing an electric current between a counter-electrode applied to the sheet from the same side as said part to be welded, in the vicinity of said bore, and an electrode applied on said part to be welded.

Abstract: This cylinder, which may be entirely pneumatic, has two working pistons 26 and 27 linked to a working rod 28, slidably mounted on which are two small auxiliary pistons 37 and 38 which can be displaced in an auxiliary chamber 35. The latter, being permanently supplied with a compressed gas, can cause the return, by means of the piston 38 or 37, of the fitting 26-27-28 to an intermediate position shown in the drawing, respectively from a fully extracted position (towards the right) of the rod 28 or a fully retracted position (to the left) of this rod.

Abstract: The welding operation performed by the clamp 12 is under the control of a welding cabinet 15 including a servo-control unit 16' and an electronic switch 17. The clamp is moved from one weld spot to another by a robot 13 under the control of a control unit 14 provided with a servo-control unit 16. The switch 17 is controlled in such a manner that the welding operation and the beginning of the clamp opening operation and the end of the clamp closing operation are under the control of the welding cabinet 15 (with the robot then remaining stationary), while displacement of the clamp synchronizing with wide opening and closing thereof are under the control of the control unit 14.

Abstract: A voltage dropping transformer for an electric welding machine, of the type in which the secondary circuit is formed by a wound strip, is provided wherein one or more cooling turns are incorporated or inserted in the windings of the primary and/or secondary circuits, separating them into several parts while being in thermal contact therewith. The turns are electrically inactive--having solely a cooling role--and do not form part of the electric circuits of the windings.