Abstract: Installations for assembling by welding or other means comprising means for positioning the various constituent parts, at least one programmeable means for assembly by welding or other means.An installation characterised in that it comprises at least one gantry (10, 11) the upper face of which accommodates the programmeable welding or other means which can be moved on at least one mobile cross member (10.sub.1, 11.sub.1) and in that means (13, 14) are provided to move constituent parts in the lower zone of the gantry and to immobilise them under the welding means.

Abstract: (a) This installation comprises means for positioning and holding car body parts and devices for welding these parts to one another. (b) This installation is characterized in that it comprises a rigid, fixed stand (1) provided in its upper part with a horizontal conveyor track (11) for carriages (12) referred to as upper carriages each having elements for positioning and holding components of the upper part of a particular car body model of the motor vehicle, and provided in its lower part with a lift (8,10) containing centering devices cooperating with the components of the lower part of a type of motor vehicle body, which lower part is common to several models.

Abstract: Installation for assembling a number of body models of a single type of motor vehicle. The installation includes:a horizontal shaft at the top of the frame for moving vertically the assemblies of elements used to position and hold components of the top part of a given motor vehicle body model while welding the components.

Abstract: A multi-point laser welding installation for vehicle bodies includes apparatus for positioning the pieces to be welded, apparatus for gripping the pieces and apparatus for welding the positioned and gripped pieces at specific points. The apparatus for positioning and gripping are provided with bearing surfaces. The shape of these surfaces conforms to the shape of the pieces. The apparatus for positioning and gripping include cavity which open the pieces at right angles. The welding apparatus is fixed on the positioning and/or gripping apparatus in order to ensure spot welding of the pieces at right angles to the cavities.

Abstract: An installation for determining the spatial coordinates of a point (P) on a piece (7) in particular for controlling a plant such as a welding plant for car bodies of motor vehicles. The installation is characterized in that it comprises a head (11) movable in a plane (X-Y) and produces a signal as a function of the distance of the point (P) in relation to the plane (X-Y), a rotor (13) on the head (11), this rotor comprising means for projecting a rotating laser beam (21.sub.4), at least three fixed targets (Q, R, S) arranged in the plane (X-Y) and the coordinates of which in this plane are known, these targets being capable of producing a signal as a function of the position (X.sub.P -Y.sub.P) of the head (11) and hence of the point to be measured (P) in the plane (X-Y). The invention is applicable to an installation for determining the spatial coordinates of a point.

Abstract: An installation for electron beam metalworking comprises an electron gun (1), a transformer and rectifier system producing a rectified high voltage supplied to the gun, a vacuum tube (23) disposed in the circuit and associated with means (21) sensitive to the current flowing through the circuit and adapted to interrupt the current when it exceeds a predetermined value. The circuit is characterized in that the positive terminal of the rectifier is connected to the gun anode (4) by way of earth (the reference potential) and the vacuum tube (23) associated with its current flow sensiive means (21) is disposed in the connection between the negative terminal of the rectifier (19) and the gun cathode (3).

Abstract: Method of and installation for spot-welding by laser beam, the method characterized in that the focusing means (3) undergoes displacement so that the point of focus (4) of the beam on the workpieces (4, 5) describes at least a path which is closed upon itself and of which the surface area of fusion obtained corresponds to the desired spot weld.The invention is applied to the welding of superposed workpieces.

Abstract: An installation for assembly and in particular for pinning the car bodies of motor vehicles, includes carriages for supporting the car bodies to be assembled by welding, and a conveyor track for displacing these carriages to an assembly station provided with welding equipment. The installation is characterized in that it includes a rigid and fixed stand, a rigid frame which reciprocates on the stand, and at least two gantry structures rigidly fixed to the frame, each gantry having apparatus for positioning and holding a particular model of car body to be welded, apparatus for reciprocating the frame on the stand in a direction parallel to the displacement of the carriages, and apparatus for locking the frame in relation to the stand so as to position one or other gantry in the assembly station.

Abstract: A method of spot-welding by laser beam, comprising a laser beam generator (10) and at least one means receiving the laser beam and focusing it on the pieces to be welded.