Installation for testing electric welding between electrodes, with parts that are out of perpendicular alignment

Abstract

The invention relates to an electric welding test installation comprising two electrodes (10, 12) aligned along a main axis (A) and, between said electrodes (10, 12), a plate (20) connected to a frame and comprising a location (22) for the positioning of two stacked flat parts (2, 4) to be welded, and a through-hole for the passage of an electrode (10), the plate (20) being connected to the frame by a pivot (34) disposed in a plane perpendicular to the main axis (A), and also comprising a locking device having a plurality of predefined angular positions relative to said perpendicular plane.

Description

[0001] DESCRIPTION

[0002] Title: Electrical Welding Test Setup Between Electrodes with Defects in the Perpendicularity of Parts

[0003] 0001. The present invention claims priority from French application 2412965 filed on November 26, 2024, the content of which (text, drawings, and claims) is incorporated herein by reference. The present invention relates to an electric current welding test setup between two electrodes with perpendicularity defects of the bearing surfaces of the assembled parts with respect to the axis of the electrodes, as well as a method for using such a welding test setup.

[0004] 0002. A known type of electrical welding test setup between two electrodes pressing two pieces together, shown in particular by document KR-A-20090031106, includes a horizontally arranged rotating circular platform held by an axial pivot fixed to a workstation frame.

[0005] 0003. The platform has several slots evenly distributed around its perimeter, each holding two superimposed parts to be assembled, which are positioned by these slots. An electrode fixed to the frame of the unit is positioned opposite a hole in each slot during the rotation of the platform, so that it comes under the parts to be assembled after each rotation, following equal fractions of a turn.

[0006] 0004. The workstation includes an upright comprising a horizontal arm having below it a movable electrode, which slides vertically so as to come above the parts to be assembled in the axis of the fixed electrode.

[0007] 0005. Various part presence control systems incorporating sensors automate the operation of the welding station. For each table stop, the system simultaneously loads two parts to be welded into an empty slot, welds the parts in the slot between the electrodes, and unloads one welded assembly into a third slot. The table then rotates a fraction of a turn to repeat the same operations. 0006. This type of installation allows for serial, repetitive testing of parts to be welded, particularly for performing weld quality tests on a sufficiently large sample.

[0008] 0007. The construction of motor vehicle bodies comprising sheet metal assemblies uses numerous electric welding points which must be qualified to ensure quality and safety.

[0009] 0008. For this purpose, robots are used for the automated welding of vehicle bodies. These robots, equipped with a relatively heavy clamp, move through space to successively clamp the sheet metal between the electrodes at each weld point, with short cycle times if possible to recoup the significant investment. There are tolerances in electrode positioning, particularly for deviations in the perpendicularity of the electrode axis, which must not compromise the quality of the welds.

[0010] 0009. In particular, certain assemblies of different materials, notably an aluminium sheet on a steel sheet using steel pins passing through the aluminium sheet, are delicate to carry out and require precise calibrations of the installation and frequent checks of the results obtained.

[0011] 0010. The type of installation according to the prior art, intended to achieve a positioning of the flat parts to be welded perpendicular to the axis of the electrodes, poses problems for qualifying welds exhibiting well-defined defects of this perpendicularity on batches of samples.

[0012] 0011. The present invention is specifically designed to avoid these problems of the prior art.

[0013] 0012. It proposes for this purpose an electric welding test installation comprising two electrodes aligned along a main axis, and between these electrodes a platform connected to a frame, comprising a positioning location for two superimposed flat pieces to be welded, and a hole for the passage of an electrode, this installation being remarkable in that the platform is connected to the frame by a pivot disposed in a plane perpendicular to the main axis, comprising a locking device according to several predefined angular positions relative to this perpendicular plane.

[0014] 0013. One advantage of this welding test installation is that by providing the locking device with several angular positions progressively offset from the perpendicular plane, it is possible to easily and quickly test the results of welds with defects exhibiting a progressive departure from the perpendicularity of the electrode axis by choosing several increasing angular deviations easily locked with a precise angle by the locking device.

[0015] 0014. It is thus possible to carry out analyses and tests of resistance on samples made in a reproducible manner to qualify the acceptable tolerances of perpendicularity defects.

[0016] 0015. These results make it possible in particular to optimize the trajectories and speed of the movements of the welding clamp carried by a robot, taking into account acceptable deviations thanks to the qualification of the welds which can be done repeatedly on a large number of samples.

[0017] 0016. The electric welding test installation according to the invention may further include one or more of the following features, which may be combined with each other.

[0018] 0017. Advantageously, the pivot is formed on a support fixed to the chassis of the installation.

[0019] 0018. In this case, advantageously the locking device includes a series of holes made on the plate and on the support, which can receive a pin engaged in a hole in the plate and the support to define an angular position.

[0020] 0019. Advantageously, the support symmetrically comprises two bosses framing the platform, each comprising a portion of the pivot. 0020. In this case, advantageously each boss comprises a series of holes arranged on an arc of a circle centered on the axis of the pivot.

[0021] 0021. Advantageously, the predefined angular positions start with an angle of 0° and increase with an increment of 1°.

[0022] 0022. Advantageously, the predefined angular positions are between 0 and 6°.

[0023] 0023. The invention also relates to a welding test method for two flat pieces with a test installation comprising any one of the preceding characteristics, remarkable in that it includes, for each predefined angular position, the welding of a batch of identical samples.

[0024] 0024. Advantageously, the test process then performs a weld strength measurement test for each batch, and then determines the maximum angular deviation corresponding to a minimum required strength.

[0025] 0025. In particular, the test method can achieve the welding of the end of a rivet engaged in a bore of an aluminium part, including a shoulder placed on this aluminium part, onto a steel part.

[0026] 0026. The invention will be better understood and other features and advantages will become more apparent upon reading the following description given by way of example, with reference to the accompanying drawings in which:

[0027] 0027. [Fig. 1] is an axial cross-section diagram of parts to be welded arranged perpendicular to the axis of the electrodes;

[0028] 0028. [Fig. 2] is a diagram showing a defect in the perpendicularity of the parts;

[0029] 0029. [Fig. 3] is a view of a platform of a test installation according to the invention in a perpendicular position; and

[0030] 0030. [Fig. 4] is a side view of this tray with a defect angle.

[0031] 0031. Figure 1 shows an upper aluminum sheet 4 to be fixed to a lower steel sheet 2, by means of a steel rivet 6 arranged along a main axis A, comprising a body engaged in a hole in the aluminum sheet and an upper flange 8 bearing on this sheet.

[0032] 0032. The lower part of the rivet 6 protrudes slightly below the aluminum sheet 4 to compress and weld itself onto the steel sheet 2 by the effect of an electric current between two electrodes aligned on the main axis A, comprising a movable upper electrode 12 clamping the stack onto a fixed lower electrode 10. With the melting of the end of the body of the rivet 6 welding onto the steel sheet 2 until the collar 8 is in contact with the aluminum sheet 4, a permanent fixing of this aluminum sheet by riveting is obtained, allowing the two different materials to be joined.

[0033] 0033. Thanks to the perpendicularity of the plates 2, 4 with respect to the main axis A, a pressure of the end of the rivet 6 is obtained uniformly distributed on the top of the steel plate 2, which gives a constant welded surface over the entire end ensuring the best hold.

[0034] 0034. Figure 2 shows a defect in perpendicularity of the clamp carrying the electrodes 10, 12 with respect to the superimposed sheets 2, 4, which forms with the plane perpendicular to the main axis A an angle a due to a bad positioning of this clamp.

[0035] 0035. Uneven support is obtained from the end of rivet 6 on the steel sheet 2, with different pressures giving an uneven quality of the weld over the entire surface.

[0036] 0036. After welding a series of samples with the same perpendicularity defect, metallurgical analyses and tensile tests make it possible to measure the mechanical resistance of rivet 6 to pull-out and the diameter actually welded, in order to accept or reject series production with such a defect.

[0037] 0037. Figures 3 and 4 show a square plate 20 comprising a positioning recess 22 for an elongated sample of lower sheet metal 2 receiving an elongated sample of upper sheet metal 4 which is arranged perpendicularly. 0038. Two opposite sides of the plate 20 have an edge plate 24 which has in the middle a rising edge forming a semicircle 26 projecting above this plate, which is centered on a horizontal axis of inclination B aligned with the top of the plate.

[0038] 0039. A support 30 fixed to the frame of the test installation not shown, has an elongated flat base along the axis of inclination B, comprising symmetrically at each end a rising boss 32 forming a semicircle fitted on the outer face of the rising edge 26 of the rim plate 24. On each side of the platform 20 a pivot 34 disposed on the axis of inclination B, connects the rim plate 24 to the boss 32.

[0039] 0040. The underside of the plate 20 is positioned at a small distance from the top of the support 30 to form an intermediate space which allows this plate to tilt also to one side or the other around the tilt axis B of the pivots 34, following a maximum angle of 6° corresponding to the maximum defect envisaged.

[0040] 0041. A hole formed in the center of the support 30 and the plate 20 allows the lower electrode 10 to engage through these elements, protruding slightly above the bottom of the housing 22, by a value between 0.5 and 1 mm, so as to ensure that the force applied by the upper electrode 12 clamping the stack of sheets 2, 4 is properly taken up by the lower electrode, without interference from the plate.

[0041] 0042. Symmetrically on each side of the plate 20, the boss 32 of the support 30 has a series of holes 36 arranged in an arc of a circle on the same radius around the axis of inclination B. On each side of the plate 20, the rising edge 26 also has a series of holes 28 arranged in an arc of a circle on the same radius, but with a small angular offset relative to those of the boss 32 so that, by fitting a pin into a hole in each part, an angle of inclination α of the plate can be formed, ranging from 0 to 6°, in increments of 1°. 0043. By simply and quickly tilting the plate 20 to the required angle, and then inserting a pin on each side into the two aligned holes 26, 38, a precise and reproducible locking of the angle of inclination α is obtained, allowing a series of welding tests to be carried out at this angle.

[0042] 0044. Alternatively, different increments of the platen's inclination angles can be used, for example, 0.5°, to obtain greater precision regarding perpendicularity defects. 0045. Advantageously, the method for qualifying the welding clamp's inclination defects comprises a series of welds on identical samples, including one batch for each increasing inclination angle, starting from perpendicularity with the angle α of 0°, which corresponds to the optimum weld strength. Each batch of samples then allows the weld quality degradation to be measured, and the maximum acceptable angle to be defined to obtain the desired strength level.

Claims

DEMANDS 1. Electric welding test installation comprising two electrodes (10, 12) aligned along a main axis (A), and between these electrodes (10, 12) a plate (20) connected to a frame, comprising a positioning location (22) for two superimposed flat pieces (2, 4) to be welded, and a hole for the passage of an electrode (10), characterized in that the plate (20) is connected to the frame by a pivot (34) disposed in a plane perpendicular to the main axis (A), comprising a locking device in several predefined angular positions relative to this perpendicular plane.

2. Test installation according to claim 1, characterized in that the pivot (34) is formed on a support (30) fixed to the chassis of the installation.

3. Test installation according to claim 2, characterized in that the locking device comprises a series of holes (28, 36) made on the plate (20) and on the support (30), which can receive a pin engaged in a hole in the plate (20) and the support (30) to define an angular position.

4. Test installation according to claim 3, characterized in that the support (30) symmetrically comprises two bosses (32) framing the platform (20), each comprising a part of the pivot (34).

5. Test installation according to claim 4, characterized in that each boss (32) has a series of holes (36) arranged on an arc of a circle centered on the axis of the pivot (34).

6. Test setup according to any one of the preceding claims, characterized in that the predefined angular positions start with an angle of 0° and increase with an increment of 1°.

7. Test installation according to any one of the preceding claims, characterized in that the predefined angular positions are between 0 and 6°.

8. Welding test method for two flat pieces (2, 4) with a test installation according to any one of the preceding claims, characterized in that it comprises, for each predefined angular position, the welding of a batch of identical samples.

9. Welding test method according to claim 8, characterized in that it then performs a weld strength measurement test for each batch, and then determines the maximum angular deviation corresponding to a minimum required strength.

10. Welding test method according to claim 8 or 9, characterized in that it performs the welding of the end of a rivet (6) engaged in a bore of an aluminium part (4), comprising a shoulder (8) placed on this aluminium part (4), on a steel part (2).

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