MXPA00010421A - Fabrication method and device of a connection by wielding of resistance with projections for metallic sheets. - Google Patents

Abstract

The present invention discloses a method for the fabrication of a connection by wielding of resistance with projections for sheets made of an electricity conductive material; in one of the sheets to be wielded a projection is preformed, being the sheets compressed in a compression unit, applying a short duration sudden jump in the current, characterized because the projection is oblong, and while the sheets are compressed from one of the faces where it is situated with a compression unit that applies a pressure of approximately between 300 and 1800 Newtons, it is configured a wielding with a sudden jump in the current of approximately 15,000 to 50,000 Amperes per space of 1 to 10 milliseconds, being the current applied to the sheet higher from the side of the pressure unit and eliminated by the subjacent sheet.

Description

METHOD AND DEVICE FOR MANUFACTURING A CONNECTION BY WELDING TO RESISTANCE WITH PROJECTS FOR METAL PLANKS DESCRIPTION The invention relates to a method of manufacturing a connection by resistance welding with projections for an electrically conductive plate, such as for example the parts that make up the bodies of automobiles, and the plates of household appliances, such as for example washing machines, refrigerators, and others. The document U S -A- 4,417,122 discloses a method and device of this kind. Said document refers to a method of manufacturing a connection by resistance welding with projections for plates according to which a projection is preformed in one of the plates to be welded. During this method, the plates are compressed in a compression unit and a short current jump is applied. This is called resistance welding with projections, through which one of the two parts to be welded has a projection _ which is compressed with a mobile electrode against a fixed welding head; during this ^ process the ledge is welded to the other plate. Electric power is controlled by means of a circuit for a very short time through the connection to be manufactured. ~ A great disadvantage of this method is that the electrode leaves a visible mark on the outer surface of the plate. These impressions must then be subjected to a finishing process, which on the one hand can comprise a polishing, which implies an additional and expensive manual operation. On the other hand, this polishing is not suitable for those surfaces of the plates that have been finished with a corrosion-resistant treatment such as galvanization or e t c t r op 1 a s t a. The object of the present invention is to provide a method and device for manufacturing a connection by welding the resistance with projections, leaving no mark on the visible part, and generating a strong structural connection capable of achieving a robust connection of the pieces where no other additional means, such as an adhesive, is necessary. This object of the invention is achieved by an oblong projection, the plates being compressed from the face where the projection is located, with a compression unit. The applied pressure oscillates between 300 and 1800 Newton, and the welding is done with a sudden jump of current of approximately 15,000 - 50,000 Amps for space of 1 to 10 milliseconds. The current is supplied to the upper plate seen from the side of the compression unit and is removed from the plate lying underneath. For this reason, protrusions are used that are compressed in one of the plates. These protrusions melt during welding so that no marks are generated on the opposite side. Preferably, the projections are compressed in the lower plate at the point where the connection is to be established, whereby the pressure of the compression unit can be limited. The invention will be described in more detail with reference to the accompanying drawings. Figure 1 illustrates a plan view of a lower plate provided with a projection. Figure 2 illustrates a cross section on the line "I I-11 in Figure 1.

Figure 3 illustrates a cross section similar to that of Figure 2 corresponding to the connection by resistance welding with protrusions before proceeding to the weld with an abrupt current jump. Figures 1 and 2 illustrate an oblong projection (2) that has been manufactured during a preliminary operation in the underlying underlay (1) by forming a pressure cavity (3) in the material from the underside through a compression tool (not illustrated) In Figure 3, a transverse section illustrates the initial position of a connection by resistance welding with projections, under which the upper external plate (5) bears against the projection (2) and then folded over the internal plate (1). Then these pieces are compressed in said po sition by the action of a compression unit (8) which is electrically connected to a source of coryx (not illustrated) through which it is possible to apply a sudden jump of current on the upper plate (5) A compression unit (9) rests on the underlying internal plate (1) through which it is possible to eliminate the current by application of the sudden jump of current under the simultaneous pressure of the compression unit (8) the connection is made.A template or shape receiver (10) is placed below the plate 4 to absorb the pressure. The tool for forming the cavity (3) in the internal plate (1) has on the compression face an elevation (6) of preferably 1.4-10 millimeters at the base and of a height such that the projection (2) ) extends between 0.6 and 0.8 millimeters per plate. The height can vary with the thickness of the plate, being preferably 0.7 millimeters. The projection is beveled at its edges forming an acute angle of preferably 45 degrees. The compression unit (8) (not shown) is operated such that the force can be adjusted between 300 and 1800 Newton, preferably between 500 and 1100 Newton. The place of the tool that configures the projection (2) is indicated in Figure 1 by reference (6). The edge (5) will have a flight (7) of only 1 millimeter, counted from the center of the projection (2) to the edge end of the upper plate (5). In order to obtain an optimal result without the connection marks being visible on the external plate, it is necessary to regulate the current supply in such a way that an abrupt current jump of 15,000 to 50,000 Amperes is applied for 1 10 milliseconds

Claims (7)

RE VINDICATIONS

1. A method of manufacturing a connection by resistance welding with projections for plates made of an electrically conductive material according to which in one of the plates to be welded a projection has been preformed, the plates being compressed in a compression unit, applying a sudden short current jump, characterized in that the projection is oblong, in as much as the plates are compressed from one of the faces where it is located with a compression unit that applies a pressure of approximately between 300 and 1800 Newton , a weld is configured with an abrupt current jump of approximately 15,000 to 50,000 Amperes for space of 1 to 10 milliseconds, the carriage being applied to the upper plate from the side of the pressure unit and eliminated by the underlying plate.

2. The method according to claim 1, characterized in that the projection is formed by a compression tool that is provided with an oblong elevation with a length of preferably 8-12 millimeters at the base, a width of 1-2.4 millimeters and a height of 0.6-1.3 millimeters, with the triangular cross section having a rounded tip.

3. The method according to one or both of Claims 1-2, acterizado because one of the plates has a folded edge that has a flight of only 1 millimeter.

4. The method according to one or more of Claims 1-3 characterized in that a shape receptor or template is applied below the outer plate inferred or YE in order to absorb the pressure exerted by the compression units.

5. A device for manufacturing a connection by resistance welding with projections according to one or more of the claims 1 to 4, characterized in that the compression tool has an elevation on its surface that has a length of 10, a width of 1. , 4 mm and a height of 0.6-0.8 mm.

6. A device for manufacturing a connection by resistance welding with projections according to one or more of Claims 1 to 5, characterized in that the compression unit is provided with a power supply element while the compression unit is provided of a current removal element from the lower internal plate

7. A connection by resistance welding with projections characterized in that it comprises two plates, one of which has a folded edge with a flight of only 1 millimeter, calculated from the center of the projection to the edge end of the upper plate, where the other plate internal has a projection, which comprises an oblong elevation, whose length is 1.4-10 millimeters at the base and its height amounts to 0.6-0.8 millimeters, it can vary with the thickness of it is preferably 0.7 millimeters, with a triangular cross section, while the plates at the point where the projection is located are compressed with a substantially equal pressure by the action of a compression unit that applies a pressure that ranges between 300 and 1800 Newton, during which the welding through an abrupt current jump of approximately 15,000-50,000 Amperes for space of 1-10 milliseconds, while on the external plate Underlying a receiver is mounted in a form or template in order to absorb the applied pressures.