FR2512718A1 - Portable electric resistance welding tongs - mounted on transformer integrated with power control unit, only one hand being required to actuate tongs - Google Patents

Abstract

Tongs consist of a single, integrated appts. where a control cabinet is fixed to a transformer with a sec. winding connected to two welding electrodes which can be moved together by a handle on the cabinet. The cabinet contains a timer and also an electrical circuit adjusting the electric power fed to the prim. winding of the transformer. The handle is used to press the two electrodes against two workpieces which are to be welded together. The control cabinet pref. includes two knobs used to adust the welding power and the welding time; and a switch which only counts the number of welding cycles above a min. power e.g. to aid welding of workpieces covered by dirt or scale. The appts. is completely self-contained appts. and can be actuated by a single human hand.

Description

 Portable welding tongs.

 The present invention relates to a portable welding pliers, comprising: two welding electrodes associated with an operating mechanism making it possible to bring them closer to one another and to ensure that they can grip with pressure two pieces to be welded; a transformer whose secondary is connected to said electrodes a power control block, making it possible to adjust the power in the primary of the transformer; and a timer block for adjusting the welding time.

 Currently, clamps of this type are known, in which the welding power control block and the welding time adjustment block are incorporated in a housing separate from the clamp and its transformer, and connected by a cord, d on the one hand to this transformer and on the other to the sector.

 The disadvantage of this kind of embodiment lies in the fact that said separate housing rests on the ground while the operator maneuvers the clamp, which can generate its movements, due to the connection existing between the clamp and this housing.

 In other pliers, the welding time control block is incorporated into the clamp, but these are pliers which do not have a power control block, and therefore are less sophisticated than those which relate to the present invention.

 The object of the present invention is to remedy the drawbacks of known pliers of the type described at the start, and in particular to make them more manageable than in the past.

 To this end, a portable welding pliers of the type defined at the start is, in accordance with the invention, characterized in that the electrodes, said mechanism, the transformer, the power control block and the timing block are produced under the as a fully integrated unit, that is, in one piece.

 As a result, such an integrated unit may advantageously comprise, on the one hand, a button for adjusting the welding power, and on the other hand a button for adjusting the welding time.

 These two buttons will be directly accessible to the operator handling the gripper, without having to move, which facilitates operations and makes them faster.

 Furthermore, considering that it is, in a known and conventional manner, a welding clamp whose timing control is effected by means of a control of the number of conduction periods, provision may be made advantageously, moreover, that it comprises, in addition to an "on-off" inverter, an "energy control" inverter, which makes it possible, when it is brought into one of its positions, to not take into account the number of conduction periods only from a certain level of welding energy.

 The "on-off" inverter cuts off the current supply to the clamp, which makes it possible to check "when empty" that the electrode clamping mechanism is operating correctly and allows the desired pressure to be obtained on the parts to be welded.

 As for the "energy control" inverter, it allows a satisfactory welding point to be achieved on dirty, scorched or rusted sheets, since the time taken by the current to pass through the less conductive layer is not taken into account. counts as welding time.

 A portable welding pliers according to the invention is shown diagrammatically, in perspective, in the single figure of the attached drawing, and this by way of non-limiting example.

 In the figure, 1 designates the two welding electrodes, one of which is movable relative to the other in order to be able to grip two sheets to be welded, and 2 designates a pivoting handle for operating the electrodes, this maneuver being able to be carried out by a articulation of a conventional mechanism (not shown), of any suitable type. The reference 3 designates a fixed handle, serving as a support for the fingers of the operator, who presses the handle 2 with the palm.

 4 shows the transformer, which constitutes a unit in one piece with said mechanism and with the control circuits, contained in a control box 5. This box 5 contains in particular, in accordance with the invention, a welding power control block, by synchronous cutting of the network voltage, this block also being of any suitable type, for example with controlled rectifiers (thyristors, triacs ...), as well as a delay block, for welding time control, this block being able, as mentioned above, to operate on the principle of counting the number of conduction periods.

 The box 5 can be connected to the alternating network by a cord 6, and it comprises on its rear face (the one through which the said cord exits) an "on-off" inverter 7, an indicator lamp or indicator lamp 8 (light-emitting diode ), showing that the clamp is powered or not, an "energy control" inverter 9, the role of which has been explained above, a button 10 for adjusting the welding power, and finally a button 11 for adjusting welding time, all commands which, as we can see, are directly accessible to the user.

 A portable welding pliers thus produced is extremely easy to maneuver, and the electronic components currently available, even as regards the power elements, make it possible to produce the control unit 5 in a space-saving form and of relatively low weight.

 As goes without saying and as it moreover already follows from the above, the invention is in no way limited to those of its modes of application and embodiments which have been more particularly envisaged; on the contrary, it embraces all its variants.

Claims (3)

 1. Portable welding tongs, comprising: two welding electrodes associated with an operating mechanism making it possible to bring them closer to one another and to ensure that they can grip with pressure two parts to be welded; a transformer whose secondary is connected to said electrodes; a power control block, used to adjust the power in the transformer primary; and a timer block for adjusting the welding time, characterized in that the electrodes (1), said mechanism (2, 3), the transformer (4), the power control block and the timer block are developed as a fully integrated unit, i.e. in one piece.  2. Pliers according to claim 1, characterized in that it further comprises, on the one hand a button (10) for adjusting the welding power, and on the other hand a button (ll) for adjusting the time of welding.  3. Pliers according to claim 1 or 2, characterized in that it comprises, in addition to an "on-off" inverter (7), an "energy control" inverter (9), which allows, when brought in one of its positions, to take into account the number of conduction periods only from a certain level of welding energy.