JP2018075604A - Resistance spot welding method of aluminum member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resistance spot welding method of an aluminum member capable of lengthening the electrode service life, and capable of also increasing the welding dot number for stably forming a melting nugget.SOLUTION: A resistance spot welding method of an aluminum member relatively rotates or rocks electrodes 11 and 13 and a polishing tool 15 in a state of push-contacting the polishing tool 15 having a polishing base board 17 having a recess part having a curved surface along a curved surface shape of an electrode tip surface and polishing sheets 19A and 19B for covering at least the recess part of the polishing base board 17 by sandwiching the polishing sheets 19A and 19B by the electrodes 11 and 13 and the polishing base board 17 after welding at least any welding dot among a plurality of welding dots of a lap joint.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a resistance spot welding method for an aluminum member.

In recent automobiles, it is essential to reduce the weight of members in order to improve fuel efficiency. For this reason, light metal materials have come to be used instead of steel materials conventionally used. In particular, an aluminum material (aluminum or an aluminum alloy) is lightweight, has a large specific strength (strength per unit weight), and is low in cost for weight reduction, and thus is suitable for mass production.
By the way, resistance spot welding is frequently used for joining automobile members. However, since an oxide film with high electrical resistance is formed on the surface of the aluminum material, the energization state changes depending on the state of destruction of the film. As a result, the current path from the electrode surface to the member to be welded deviates from the center of the electrode, and the welding nugget may not be generated properly.
Therefore, in order to destroy the oxide film on the surface of the aluminum material, techniques for providing grid-like irregularities on the electrode surface or providing link-like projections (protrusions) have been developed (Patent Documents 1 and 2). In addition, aluminum having a low melting point may be fused to an electrode made of pure copper or Cr-containing copper, or Cu and Al of the electrode may react to form a Cu—Al alloy layer. In that case, when the fused metal or alloy layer develops, the local profile of the electrode changes, and the energized state becomes unstable. As a result, the weld nugget is cracked or blowholes are generated at a stage where the number of welding points (number of continuous hit points) is small. In resistance spot welding, in order to stabilize welding quality (stable welding nugget formation), dressing is generally performed in which the surface of an electrode is cut with a shaping blade after welding a predetermined number of times. By this dressing, the electrode tip can be regenerated to the initial shape (Patent Document 3).

US Pat. No. 5,304,769 U.S. Pat. No. 8927894 JP2015-58446A

However, for regeneration of the initial shape by dressing, the electrode is usually cut with a cutting allowance of 0.2 mm or more. In resistance spot welding of an aluminum material, since the molten nugget is disturbed at a stage where the number of hit points is small as described above, the frequency of dressing must be increased, and the consumption of the electrode increases. Therefore, the problem that the lifetime of an electrode becomes short arises.
In addition, in the methods described in Patent Documents 1 and 2, since the projection exists at the tip of the electrode, it can only be shaped with a cutting tool, and the life of the electrode cannot be extended.

  This invention solves the said problem, and it aims at providing the resistance spot welding method of the aluminum member which can increase the number of welding points in which a molten nugget is stably formed.

One aspect of the present invention is a resistance spot welding method for an aluminum member that performs resistance spot welding by pressing an electrode against a lap joint in which a plurality of aluminum materials are stacked,
The pair of electrodes is made of copper or a copper alloy, and has a curved shape on at least a part of the electrode tip surfaces facing each other,
After welding at least one of the plurality of welding points of the lap joint, a polishing substrate having a concave portion having a curved surface along the curved surface shape of the electrode tip surface, and at least the concave portion of the polishing substrate. A polishing tool having a polishing sheet covering the electrode, wherein the electrode and the polishing substrate are pressed against each other with the polishing sheet sandwiched between them, and the electrode and the polishing tool are relatively rotated or oscillated. It is the resistance spot welding method of the aluminum member which has a process.
According to this resistance spot welding method for an aluminum member, since the electrode is polished while being pressed against the recess of the polishing substrate via the polishing sheet, the shape of the recess of the polishing substrate is changed to that of the electrode after polishing. The shape accuracy can be reflected, and the electrode can be polished with high dimensional accuracy with a small polishing allowance. As a result, the life of the electrode can be extended, and the shape change of the electrode tip surface is reduced, so that stable molten nugget can be formed.

Moreover, it is preferable that the said polishing sheet is arrange | positioned at the said polishing substrate so that attachment or detachment is possible.
According to the resistance spot welding method of the aluminum member, the polishing sheet can be exchanged. Therefore, the polishing surface of the polishing sheet can always be kept constant, and the electrode can be polished with high accuracy.

Moreover, it is preferable that the said polishing sheet is arrange | positioned so that relative movement with respect to the said polishing substrate is possible.
According to this resistance spot welding method of an aluminum member, the polishing sheet in contact with the electrode is renewed. Therefore, the polishing surface of the polishing sheet can be always kept in a constant state, and the electrode can be polished with high accuracy.

Moreover, it is preferable that the said electrode grinding | polishing process is implemented within 5 points | pieces of the said welding hit points.
According to this resistance spot welding method for aluminum members, it becomes possible to stably carry out a number of spot weldings in a state where the quality of the welding nugget is stabilized.

The electrode polishing step is preferably performed for each of the plurality of welding points.
According to the spot welding method for aluminum members, a high-quality molten nugget can be obtained more stably even if the number of welding points increases.

  According to the present invention, the electrode life can be extended, and the number of welding points at which the molten nugget is stably formed can be increased.

It is explanatory drawing which shows the mode of the electrode grinding | polishing process of grind | polishing the electrode surface. It is a perspective view which shows the external appearance of a grinding | polishing board | substrate. It is the III-III sectional view taken on the line of the polishing substrate shown in FIG. It is sectional drawing of an R-type electrode. It is sectional drawing of a DR type electrode. It is process explanatory drawing which shows the procedure of the resistance spot welding of an aluminum member. It is process explanatory drawing which shows the procedure of the resistance spot welding of an aluminum member. It is process explanatory drawing which shows the procedure of the resistance spot welding of an aluminum member. It is process explanatory drawing which shows the procedure of the resistance spot welding of an aluminum member. It is a schematic block diagram which shows the dress station and spot welder by which the grinding | polishing tool is mounted. It is a schematic block diagram of the grinding | polishing unit in which the grinding | polishing tool was accommodated. It is the elements on larger scale of the spot welding machine which shows the structure which has arrange | positioned the grinding | polishing tool to the spot welding gun.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
The resistance spot welding method of the present invention includes a welding process in which an electrode is pressed against a lap joint in which a plurality of aluminum materials are stacked and resistance spot welding is performed, and an electrode polishing process in which the electrode is polished. The welding process is a known resistance spot welding, but since the welding target is an aluminum material, electrode polishing is required. The electrode polishing is performed after welding of at least one of the plurality of welding points in the lap joint.

<Aluminum material>
Here, as an aluminum material used as a material to be welded, for example, JIS A1000 series, A2000 series (Al-Cu series alloy), A3000 series (Al-Mn series alloy), A4000 series (Al-Si series alloy), A5000 series. (Al-Mg based alloy), A6000 based (Al-Mg-Si based alloy), A7000 based (Al-Zn-Mg based alloy, Al-Zn-Mg-Cu based alloy) aluminum alloys.

  As the aluminum material, for example, a plate material having a thickness of 0.5 to 5.0 mm made of the above aluminum alloy can be used. Moreover, aluminum alloy castings, such as AC4CH, aluminum die-casting alloys, such as ADC3, and extrusion materials, such as 7N01, can also be used. The A6000 series alloy can be improved in strength by heat treatment, and in particular, it can be made into a member having higher strength by performing T6 treatment after processing into a predetermined shape.

  A plurality of the above-described plate materials, extruded materials and the like are overlapped to form a lap joint. This lap joint becomes a member to be welded, and resistance spot welding is performed at a plurality of welding points.

<Electrode polishing process>
FIG. 1 is an explanatory view showing a state of an electrode polishing step for polishing an electrode surface.
The electrodes 11 and 13 are made of copper or a copper alloy, and have a curved shape on at least a part of the electrode tip surfaces facing each other.

  In the electrode polishing step, a polishing tool 15 is disposed between the electrode 11 and the electrode 13. The polishing tool 15 includes a polishing substrate 17 and polishing sheets 19A and 19B. The polishing sheet 19 </ b> A is disposed between the polishing substrate 17 and the electrode 11, and the polishing sheet 19 </ b> B is disposed between the polishing substrate 17 and the electrode 13.

2 is a perspective view showing the appearance of the polishing substrate 17, and FIG. 3 is a cross-sectional view taken along the line III-III of the polishing substrate 17 shown in FIG.
The polishing substrate 17 includes a concave portion 21A on an upper surface 17A that is one main surface of a flat plate shape, and a concave portion 21B on a lower surface 17B that is the other main surface. The recessed portion 21A is a unidirectional groove along the Y direction and has a curved surface along the curved shape of the electrode tip surface of the electrode 11 (see FIG. 1) along the X direction in the drawing. Similarly, the recessed portion 21B is a recessed groove along the Y direction, and has a curved surface along the curved shape of the electrode tip surface of the electrode 13 along the X direction.

  The material of the polishing substrate 17 is made of a material having a hardness higher than that of the electrodes 11 and 13. It is known that the shapes (particularly curvature) of the electrodes 11 and 13 have a great influence on the welding quality. If the hardness of the polishing substrate 17 is lower than the hardness of the electrodes 11 and 13, it is difficult to ensure the accuracy of the electrode shape after polishing. As a material for the polishing substrate 17, steel, stainless steel (SUS304, etc.), titanium, or the like can be used.

  As shown in FIG. 3, the recesses 21 </ b> A and 21 </ b> B are formed in regions of widths W <b> 1 and W <b> 2 with respect to the X direction centering on the center point O of the polishing substrate 17. Both ends of the polishing substrate 17 in the X direction are flat upper surface 17A and lower surface 17B, and are supported by a support member (not shown).

  The recess 21A has a radius of curvature R1 in the ZX plane, and the recess 21B has a radius of curvature R2 in the ZX plane. These curvature radii R1 and R2 are the same as the curvature radii of the electrode tip surfaces of the electrodes 11 and 13.

4 is a cross-sectional view of the R-type electrode, and FIG. 5 is a cross-sectional view of the DR-type electrode.
The shape of the electrodes 11 and 13 is that the R (Radius) type shown in FIG. 4 and the DR (Dome Radius) type shown in FIG. 5 are easy to stabilize the flow path of the welding current, and resistance spot welding at the welding spot is continuously performed. Even if it implements, since there is little variation in the size of a welding nugget, it is preferred.

  The R-type electrode has an electrode tip surface formed with a single radius of curvature R, and the DR-type electrode has a radius of curvature Rc1 on the radially outer side of the electrode tip surface, and the center portion of the electrode wire end surface has a width d. In the range, the radius of curvature Rc2 is larger than the radius of curvature Rc1. In either case, the electrode tip has a curved surface. Note that the radii of curvature R1 and R2 of the recesses 21A and 21B of the polishing substrate 27 described above are formed as a radius of curvature R in the case of the R type shown in FIG. 4, and as a radius of curvature Rc2 in the case of the DR type shown in FIG. .

  As the material of the electrodes 11 and 13, pure copper such as oxygen-free copper or tough pitch copper, chromium-containing copper, zirconium-containing copper, or the like is preferably used. The dimensions of the electrodes 11 and 13 are preferably 12 to 22 mm in diameter, and the curvature radius R of the electrode tip is preferably 80 to 120 mm.

<Polished sheet>
The polishing sheets 19A and 19B are configured to hold abrasive grains with a resin binder based on polishing paper, preferably polishing cloth (including resin). When the electrodes 11 and 13 are pressed against the polishing sheets 19A and 19B, abrasive grains are arranged along the polishing substrate 17 by an elastic resin binder, whereby the electrodes 11 and 13 can be polished with high dimensional accuracy. Abrasive grains having a grain size of 320 # to 1000 # are preferably used because the shape of the electrode tip can be secured.

  In particular, an electrode having a radius of curvature R at the tip, such as an R type or DR type, reflects the shape accuracy of the recess portion of the polishing portion on the polishing substrate 17 and can be polished with high accuracy. As a result, it is possible to accurately polish the predetermined tip shape of the R-type and DR-type electrodes, which has conventionally been difficult to regenerate the shape.

  The polishing sheets 19 </ b> A and 19 </ b> B are arranged so as to be detachable from the polishing substrate 17 or movable relative to the polishing substrate 17. Thus, each time the polishing of the electrode is completed, the polishing sheets 19A and 19B can be moved, and the sheet position where the electrode has not yet been hit can be arranged facing the electrode. As a result, the properties of the electrode pressing positions of the polishing sheets 19A and 19B can always be made uniform, and the polishing sheet is not clogged and the polishing unevenness does not occur, so that the shape accuracy of the electrode after polishing can be increased.

<Resistance spot welding method>
Next, a resistance spot welding method for an aluminum member will be described.
6A to 6D are process explanatory views showing step by step the resistance spot welding of an aluminum member.
As shown in FIG. 6A, first, the polishing tool 15 is arranged with the axis aligned between the electrode 11 and the electrode 13. At this time, at least the recesses 21A and 21B of the polishing substrate 17 are covered with the polishing sheets 19A and 19B.

  Next, as shown in FIG. 6B, the electrodes 11 and 13 are brought close to each other, and the polishing tool 15 is sandwiched therebetween. In addition to the operation of moving both, the electrodes 11 and 13 may be an operation of using one as a fixed electrode and the other as a movable electrode to bring the movable electrode closer to the fixed electrode. When the electrodes 11 and 13 sandwich the polishing tool 15, the electrodes 11 and 13 are pressed against the recesses 21A and 21B of the polishing substrate 17 via the polishing sheets 19A and 19B.

  Then, as shown in FIG. 6C, the polishing tool 15 is rotated or oscillated around the central axes of the electrodes 11 and 13 in a plane parallel to the plate surface of the polishing substrate 17. The rotation or swinging mechanism of the polishing tool 15 only needs to be able to stably rotate the polishing tool 15, and a known mechanism can be used.

  After the relative rotation or swinging of the electrodes 11 and 13 and the polishing tool 15 is completed, the electrodes 11 and 13 are moved away from the polishing tool 15 as shown in FIG. 6D. By the above polishing, the electrode tip surfaces of the electrodes 11 and 13 are regenerated to the initial electrode shape.

  By polishing the tip surfaces of the electrodes 11 and 13 in the above procedure, the amount of consumption of the electrode can be reduced compared to the case of cutting the electrode. Further, since the electrodes 11 and 13 and the polishing substrate 17 having a certain hardness are polished by sandwiching the polishing sheets 19A and 19B, the shape of the polishing substrate 17 is accurately reflected in the electrode, and the shape of the tip of the electrode is high. Maintained with accuracy. Thereby, even if the number of welding points increases, a stable nugget quality free from cracks, sink marks, blow holes and the like can be obtained.

  In addition, the axes of the electrodes 11 and 13 and the substrate surface of the polishing substrate 17 are arranged at a substantially right angle, and the recessed portions 21A and 21B of the polishing substrate 17 and the electrode tip surfaces of the electrodes 11 and 13 have substantially the same size and shape. Become. Therefore, the curved shape of the tip of the electrodes 11 and 13 can be easily and accurately obtained by relative rotation or swinging of the electrodes 11 and 13 and the polishing substrate 17.

  Further, since the polishing sheets 19A and 19B are detachably attached to the polishing substrate 17 and are movably disposed with respect to the polishing substrate 17, the polishing surfaces of the polishing sheets 19A and 19B can always be maintained in a constant state. As a result, the electrode tip surface can be polished with high accuracy and finished in a desired electrode shape.

  In addition, the electrodes 11 and 13 may be polished with a frequency of welding hit points of 10 times or less, preferably 5 times or less. More preferably, polishing may be performed every time after welding at each welding spot. Thereby, even if the number of welding points increases, a more stable and high-quality molten nugget can be obtained, and a number of resistance spot weldings can be stably performed.

  Next, a procedure for performing the steps of the above resistance spot welding method with a spot welder will be described. 7 to 9 shown below are one configuration example for explaining the steps of the resistance spot welding method, and are not limited to the configuration of the illustrated example.

  As described above, the polishing tool 15 may be configured to perform offline polishing independent of the spot welder, but may be configured to be incorporated into the spot welder and polished online.

FIG. 7 is a schematic configuration diagram showing a polishing apparatus 25 and a spot welder 27 on which the polishing tool 15 is mounted.
The spot welder 27 has a spot welding gun 31 having electrodes 11 and 13 on the robot tip axis. The spot welding gun 31 is moved to a desired position in a desired posture by a plurality of drive shafts of the spot welder 27.

  A polishing device 25 is disposed in a part of the movable range of the spot welding gun 31 by the spot welder 27. The polishing apparatus 25 includes a polishing unit 33 in which the polishing tool 15 is accommodated. The polishing unit 33 is provided in the polishing apparatus 25 in such a posture that the electrodes 11 and 13 of the spot welding gun 31 can hold the polishing tool 15.

FIG. 8 is a schematic configuration diagram of the polishing unit 33 in which the polishing tool 15 is accommodated.
The polishing unit 33 includes a polishing tool 15, a casing 35 that supports the polishing tool 15, and a polishing sheet supply mechanism 37 built in the casing 35.

  The polishing sheet supply mechanism 37 polishes the supply side reel 41 around which the polishing sheet is wound, the collection side reel 43 around which the used polishing sheet is wound, and the polishing sheet 19B arranged below the polishing substrate 17. And a reversing roller 45 for reversing the substrate 17 upward.

  The polishing sheet fed from the supply-side reel 41 is supplied below the polishing substrate 17, and this polishing sheet 19 </ b> B is sent above the polishing substrate 17 by the reverse roller 45. The polishing sheet 19 </ b> A above the polishing substrate 17 is wound around the collection side reel 43 by driving the collection side reel 43. As a result, the polishing sheet is continuously supplied below and above the polishing substrate 17.

  The spot welder 27 shown in FIG. 7 moves the spot welding gun 31 to the polishing device 25 after spot welding the lap joint as a member to be welded, and sandwiches the polishing tool 15 of the polishing device 25 between the electrodes 11 and 13. To do. In this state, the polishing unit 33 performs the above-described electrode polishing step.

  According to this configuration, since the polishing tool 15 is arranged in the polishing apparatus 25, the operation of the electrode polishing process is incorporated into the program for controlling the spot welder 27, so that the spot welding process and the electrode polishing process can be performed according to the program. Can be implemented automatically. According to this, the electrode can be polished without human intervention, and the welding operation can be continuously performed with high efficiency. Therefore, a spot welding line suitable for mass production can be constructed.

The polishing tool 15 can be provided in the spot welding gun 31 of the spot welder 27 in addition to being provided in the above-described polishing apparatus.
FIG. 9 is a partial enlarged view of a spot welder showing a configuration in which the polishing tool is disposed on the spot welding gun 31.

  In this case, the spot welding gun 31 is provided with a plunger 51 that can move up and down in parallel with the axial direction of the electrodes 11 and 13 and can rotate (spin). A polishing unit 33 on which the polishing tool 15 is mounted is attached to the lower end portion of the plunger 51, and the polishing tool 15 can be disposed between the electrodes 11 and 13 at the lowered position of the plunger 51. The position of the polishing tool 15 indicated by the solid line in the figure is the polishing position.

  Further, the polishing tool 15 is pulled out from between the electrodes 11 and 13 when the plunger 51 is rotationally driven in the PA direction. Then, the plunger 51 is driven upward in the PB direction and is rotated in the PC direction on the upper end side, whereby the polishing tool 15 is disposed at the retracted position.

  As described above, the spot welding gun 31 having the above-described configuration is movable between the polishing position where the polishing tool 15 is disposed between the electrodes 11 and 13 and the retracted position at the upper end. According to this configuration, when performing resistance spot welding of a plurality of welding points, the electrode polishing step can be performed on the spot welding gun 31 at a position near the welding point. Therefore, the spot welder 27 does not need to move the spot welding gun 31 to the polishing apparatus every time the electrode is polished, and can perform continuous resistance spot welding more efficiently.

  In addition, the above-described electrode polishing step is preferably performed at a welding spot number within 10 points, more preferably within 5 points, and even more preferably every welding spot, in order to stabilize the quality of the molten nugget by resistance spot welding. Is preferred.

  As described above, the present invention is not limited to the above-described embodiments, and those skilled in the art can make changes and applications based on combinations of the configurations of the embodiments, descriptions in the specification, and well-known techniques. This is also the scope of the present invention, and is included in the scope for which protection is sought.

  For example, any one of the electrodes 11 and 13 and the polishing tool 15 may be rotated or oscillated, or both may be simultaneously rotated or oscillated.

  In the above example, the electrode 11 and the electrode 13 are simultaneously pressed against the polishing tool 15 for polishing. However, only one of the electrode 11 and the electrode 13 may be pressed against the polishing tool 15 for polishing. In that case, it is only necessary to form a recess on only one side of the polishing substrate 17.

  Furthermore, although the recessed part of the grinding | polishing board | substrate 17 demonstrated as a recessed groove with the same cross-sectional shape continuing in one direction, it is not restricted to this, A rotationally symmetrical bowl-shaped recessed part may be sufficient.

  And although the electrodes 11 and 13 have illustrated the structure of direct spot welding, it is not restricted to this, Indirect spot welding and series spot welding which can perform single-sided welding may be sufficient.

  A lap joint was formed by stacking aluminum plates of material JIS A6022, a plate thickness of 2.0 mm, and a plate width of 80 mm. This lap joint was spot spotted at a pitch of 100 mm, and was subjected to resistance spot welding at 50 consecutive spots without performing dressing (shaping by electrode cutting) during the following welding conditions.

・ Welding current: 36 kA
-Energizing time: 400 msec
・ Electrode pressure: 4kN
-Electrode: Material Cu-1% Cr, R-type electrode
Diameter 19mm, tip radius of curvature 100mm

  In the electrode polishing between the welding points, the polishing substrate was made of material SUS304, and abrasive paper having a particle size of 400 # was wound around the polishing substrate and fixed. Further, the electrode was pressed so that the tip of the electrode hits a dent in the direction perpendicular to the polishing substrate, and was rotated 10 times at a speed of 1 rotation / second. In Example 1, the electrode polishing process was performed for each welding spot, in Example 2, the electrode polishing process was performed for every five welding spots, and in the comparative example, the electrode polishing process was not performed.

  A cut piece cut in half in the depth direction of the spot of resistance spot welding is embedded in the resin so that the plate thickness direction can be observed, then mirror-polished, and subjected to Keller's etching treatment to give a macrostructure observation test piece It was. In this test piece, the nugget size, the presence or absence of cracks in the weld, and the presence or absence of blowholes were confirmed.

  The nugget size was evaluated as “◯” when the rate of change was less than 10% compared to the first nugget size, “Δ” when 10-30%, and “x” when it exceeded 30%. In the evaluation of cracks, the case where no crack was generated was evaluated as ◯, and the case where the crack was generated was rated as x. In the evaluation of the blowhole, the case where the blowhole was not observed in the nugget portion was evaluated as ◯, and the case where the blowhole was observed as ×. The evaluation results are shown in Table 1.

  After continuous resistance spot welding was started, Al began to adhere to the electrode surface with several welding points in both the examples and comparative examples. In the comparative example that was not polished, cracking started to occur at the fifth welding point. Further, a blow hole was observed at the tenth welding spot. As for the nugget size, the rate of change increased from the 10th point, and a coarse nugget was formed at the 20th point.

  In Example 2 where the electrode polishing step was performed with 5 welding points, no blowholes or cracks occurred even after the welding point ended 50 points, and the change in nugget size slightly increased after 20 points, In practical use, there was no effect.

  In Example 1 where the electrode polishing process was performed each time, blow holes and cracks did not occur even after the welding hitting point was 50 points, and the nugget size was hardly changed.

11, 13 Electrode 15 Polishing tool 17 Polishing substrate 19A, 19B Polishing sheet 21A, 21B Recessed portion

Claims (5)

A resistance spot welding method for an aluminum member in which an electrode is pressed against a lap joint in which a plurality of aluminum materials are stacked and resistance spot welding is performed,
The pair of electrodes is made of copper or a copper alloy, and has a curved shape on at least a part of the electrode tip surfaces facing each other,
After welding at least one of the plurality of welding points of the lap joint, a polishing substrate having a concave portion having a curved surface along the curved surface shape of the electrode tip surface, and at least the concave portion of the polishing substrate. A polishing tool having a polishing sheet covering the electrode, wherein the electrode and the polishing substrate are pressed against each other with the polishing sheet sandwiched between them, and the electrode and the polishing tool are relatively rotated or oscillated. A resistance spot welding method of an aluminum member having a process.   The resistance spot welding method for an aluminum member according to claim 1, wherein the polishing sheet is detachably disposed on the polishing substrate.   The resistance spot welding method for an aluminum member according to claim 1 or 2, wherein the polishing sheet is disposed so as to be relatively movable with respect to the polishing substrate.   The resistance spot welding method of the aluminum member as described in any one of Claims 1-3 which implements the said electrode grinding | polishing process within the number of the said welding hit points within 5 times.   The resistance spot welding method of the aluminum member as described in any one of Claims 1-4 which implements the said electrode grinding | polishing process for every several said welding spot.

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