JPS5825881A - Resistance welding method - Google Patents

Abstract

PURPOSE:To form a welded nugget of uniform thickness in a weld line direction in mush-seam resistance welding of sheets of Al metals by forming electrically insulating films on the opposite surfaces to be welded of the Al alloys to be welded beforehand. CONSTITUTION:In the stage of sandwiching Al or Al alloy sheets 1, 1' which are sheets of <0.10mm. from above and below with an upper roller electrode and a lower roller electrode 3' under pressure, and subjecting the sheets to mush- seam resistance welding by conducting electricity thereto, electrically insulating film 4 of 0.1-5.0mum thickness consisting essentially of Al2O3 are beforehand formed on the surfaces of the Al sheets to be welded by an anodizing or chemical oxidation method. The parts to contact with the electrodes 3, 3' are removed of the films 4 to maintain conductivity with the roller electrodes. Said parts are pressurized and are supplied electric current with the electrodes 3, 3', whereby these parts are resistance-welded. The thin films of the electrically insulating films crack finely, thus forming welded nuggests 5 of roughly a uniform thickness on the parts 6a near the boundaries 6 of the superposed parts along said boundaries.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a resistance welding method, and more particularly to a pine seam electric resistance welding method for aluminum plates or aluminum alloy plates.

The edges of aluminum plates or aluminum alloy plates (hereinafter referred to as aluminum (alloy) plates) are overlapped to form an overlapping part, and between opposing electrodes that are wider than the width of the overlapping part, When performing seam resistance welding by suppressing and energizing the overlapped portion to crush the overlapped portion and perform seam resistance welding, the following problems occur. (a) Welding under conditions where weld nuggets are not generated, ie, solid phase welding, does not cause streak rush (molten metal flying out), but the weld strength is low. This is considered to be due to the dense aluminum oxide layer on the joint surface, which makes it impossible to obtain solid phase welding (ie, forge welding) with high welding strength as in the case of low carbon steel sheets. (b) In the case of fusion welding (that is, normal welding), if the pressing force from the electrode is low, the pressing force will be particularly small near the widthwise ends of the overlapped parts, and therefore the contact electrical resistance on the entire overlapped area will be large. This is thought to be due to the fact that the vicinity of the end is overheated and melted, which tends to cause severe splash. As a result, the properties of the welded portion become poor, and furthermore, the electrode becomes immediately contaminated and becomes unusable. - Even if the edge of the blade melts and a significant sedge lash occurs, it will not melt easily near the center of the overlapping part in the width direction, and the welding strength at that center is extremely low. . In addition, due to the influence of the alternating current waveform used as the welding current, molten nuggets may not be continuously generated at the widthwise ends of the overlapped portion, or even if they are generated, the size of the molten nuggets may be small. The change in strength is significant, making it difficult to obtain uniform welding strength in the welding line direction. Therefore, the strength, appearance and airtightness of the obtained welded part are not satisfactory. (
c) When the pressing force by one electrode is increased, the electrical contact resistance at the overlapping surfaces is reduced, and molten nuggets are difficult to form even when a large current is passed. ) The difference between the contact electrical resistance at the overlapping surface and the contact electrical resistance at the electrode surface is small,
Moreover, since the melting point of aluminum (alloy) is relatively low, if local melting occurs on the overlapping surfaces, it is easy to melt immediately to the electrode contact surface, and therefore the electrodes are easily contaminated.

Therefore, it is not possible to obtain a satisfactory pine seam resistance weld, and therefore, the pine seam weld has a smaller step than a normal overlapping seam weld, and when applied to the side joint of a can body, for example, it is difficult to obtain a protective coating with paint. (for corrosion protection against acidic liquids, etc.) and the formation of two parts with the lid.
Although the method has advantages such as the ease of ensuring airtightness of the heavily seamed portion, it has been difficult to obtain a practical seam resistance welded portion of an aluminum (alloy) plate.

The present invention aims to solve the problems of the prior art described above.

In order to achieve the above object, the present invention provides a method for welding a stacked portion of aluminum plates or aluminum alloy plates by mating seam resistance welding between opposing electrodes, in which opposing surfaces of the stacked portion of the aluminum plate or aluminum alloy plate are Matsushi seam resistance welding of aluminum plates or aluminum alloy plates, each of which is characterized by a very thin electrically insulating film that is tightly formed to produce minute racks due to the deformation of the metal during matsushi seam resistance welding. It provides law.

The present invention will be described below with reference to the drawings. 1st
In the figure, 1 and 1' are aluminum (alloy) plates, and 2 is an overlapping part. 3 is the upper roller electrode,
3' is the lower roller electrode (aluminum (alloy plate)
(a wire electrode (not shown) may be inserted between 1 and 1' and the roller electrode 3' and 3') is usually made of steel or copper alloy, and during that phase, a wire electrode (not shown) may be inserted so as to enable matt seam welding. , the width of the overlapping portion 2, and the width of the overlapping portion 2' (see FIG. 2) after mating (that is, after mat seam resistance welding).

A very thin electrically insulating coating 4 is closely formed on opposing surfaces 1a and 1'a of the overlapping portion 2 of the aluminum (alloy) plates 1, 1'. The electrically insulating film 4 is
As shown in Figure 2, the matshu seam is brittle enough to cause minute cracks due to deformation of the metal (i.e. aluminum (alloy)) during welding, and adheres well to the aluminum (alloy) plates 1 and 1'. It is necessary to do so.

Furthermore, it is necessary that the electrical insulation properties will not be lost due to decomposition or deterioration at the heating temperature during welding.

When the electrically insulating film 4 that satisfies the above conditions is formed, under relatively wide welding conditions, the melting layer 5 as shown in FIGS. If the welding speed is set within an appropriate range for the welding current frequency, the fourth
As shown in the figure, a welding pad 5 having a substantially uniform thickness is formed along the welding line direction without affecting the peak value and zero value of the current value.

Although the reason is not necessarily clear, it is assumed to be as follows.

As shown in FIG. 2, cracks 7 occur in the electrically insulating coating 4 due to the mating of the metal during mating seam resistance welding. b, 1' The deformation of the metal is large at the position corresponding to the vicinity of b, and the deformation of the metal is relatively small. 1c, 1'c near the center of the overlapping part 2' after matashing and the edge of the overlapping part 2' after matashing. Part 1 b, l
It is small at the position corresponding to the opposite side 1d and I'd of 'b'. Furthermore, the interface end 1 b' of the end edge 1b, l'b,
l'b' is matshu no sai cuteno 1 f,
1'f is a portion formed by wrapping around, and the electrically insulating film 4 does not originally exist. And metal flows into the crack 7 of Matshu. Therefore, the contact area between metals is relatively large, and the overlapping part interface 6 after mating
The electrical contact resistance of the portion 6b near the edge is relatively small, and therefore the generation of Joule heat is also small, making it difficult for melting to occur. On the other hand, in the vicinity of the center 6a, since the overlapping area of the cracks 7 is relatively small, the electrical contact resistance is small and the generation of Joule heat is small, so it is assumed that the molten metal 5 is generated. And the edge vicinity interface 6b
is strongly pressed in a solid state, so that the molten metal of the molten nugget 5 is difficult to splash out through the interface, and the contact surface 8 between the electrode 3.3' and the aluminum (alloy) plates 1, 1' , 8' is significantly smaller than that at the interface 6 of the overlapping part after mating, so the generation of Joule heat is also small.
It is presumed that due to the cooling effect caused by mating, the aluminum (alloy) plate parts 1e and l'e near the surface of the overlapping part 2' after matashing, that is, the bath contact part, do not melt and remain in a solid phase. Ru.

If the electrically insulating coating 4 is formed only on one of the opposing surfaces of the overlapping portion 2, for example, only on the surface 1a, the electrically insulating coating 4 may be formed near the center of the overlapping portion interface 6 after mating as described above. Since the difference in electrical contact resistance between the portion 6a and the portion 6b near the edge does not become large, the molten nugget 5 is applied only to the portion 6a near the center without causing splash.
is difficult to generate.

The aluminum (alloy) plate to which the present invention is applied preferably has a thickness of about 0.10w or more. Plate thickness is 0.1
This is because if it is thinner than 0 m, the distance between the overlapping surfaces on which the liquid is applied and the electrode contact surface is too short, and the melted waste tends to reach the electrode contact surface.

The width of the overlapping portion 2 is preferably about 0.3 to 1.5 tag, more preferably about 0.4 to 0.8 fi.

This is because if the width is smaller than about 0.3 m, the width of the molten nugget 5 becomes too small and sufficient welding strength cannot be obtained. On the other hand, if the width is larger than about 1.5 m, there will be less metal flow during mating in the widthwise center of the overlapping part, and the generation of cracks in the electrically insulating film in that area will be extremely small, so welding conditions may be This is because even if a slight change occurs, the amount of heat generated at the overlapping surfaces will not be constant and the welded state will become unstable.

As the aluminum (alloy) plate, pure aluminum plate and various aluminum alloy plates are used as appropriate depending on the purpose.
1. ．． 0 to 1.5%) is particularly excellent in terms of high welding strength and no splashing, as shown in Examples below. The reason for this is not necessarily clear, but it is presumed that because it contains an appropriate amount of Mg, the melting point does not become particularly low, and furthermore, because it contains an appropriate amount of Mn, the electrical conductivity and thermal conductivity are slightly lower.

The electrically insulating film 4 is formed on an aluminum (alloy) plate by an anodic oxidation method (e.g., sulfuric acid bath, chromic acid bath, oxalic acid bath, phosphoric acid bath, etc.) or chemical oxidation method (e.g., MBV method, etc.). A coating mainly composed of aluminum oxide formed by the boehmite formation method described above is particularly suitable. It is presumed that this is because it has excellent adhesion to the aluminum (alloy) plate that is the substrate and is moderately brittle, and the area where cracks occur increases approximately in proportion to the degree of deformation of the metal.

The thickness of the coating is preferably 0.1 to 5.0 μm. If it is as thin as 0.1 μm, the contact electrical resistance value of the overlapping surfaces will be low9, and accordingly, the difference in contact electrical resistance between the center and end portions of the overlapping surfaces in the width direction will also be small. It becomes difficult to form a molten slit near the center of the overlapping surfaces.

On the other hand, if it is thicker than 5.0 μm, the electrical contact resistance near the center in the width direction of the overlapping surfaces becomes too large.
This is because even if a slight change in welding conditions occurs, the heat generation at the overlapping surfaces becomes unstable.

In addition, adhesive thermosetting resins such as epoxy resins, phenolic resins, and urea resins, or alkali metal silicates, phosphates,
Single inorganic adhesives such as colloidal silica and colloidal silica, or coatings made of these and fine powder inorganic substances (e.g. carden, alumina, titanium oxide, zinc oxide, chromium oxide, iron oxide, barium carbonate, etc.) can also be used. However, compared to the coating mainly composed of aluminum oxide, sedge lash is a little more likely to occur even under optimal welding conditions. In this case as well, the coating thickness is preferably 0.1 to 5.0 μm. The reason is the same as in the previous case.

Thermoplastic resin coating (alone or containing fine powder),
In the case of chemically treated coatings using a mixed bath of phosphoric acid and chromic acid, it is difficult to produce molten nuggets without generating a large amount of sedge lash, regardless of the coating thickness.

When forming the anodic oxide film or chemical oxide film, as in the case of FIG.
, 1' are formed on both sides of at least the overlapping part 2 and the neighboring parts 1g+1'g, and then the coating 4 in the vicinity of the parts contacting the electrodes 3, 3' is removed by mechanical means (e.g. It may also be deleted using an IJ cutting cutter). Furthermore, as disclosed in Japanese Patent Application Laid-open No. 56-23389, when welding is performed using a set of a cooled vertically elongated electrode and a relatively large-diameter rotating electrode (via a wire electrode if necessary), However, it is possible to obtain a good melted nugget without necessarily removing the coating 4. It is assumed that this is because the contact area between the plate and the electrode is large, so that the heat generated at the contact surface is absorbed by the electrode, thereby preventing the temperature from rising to the point where the plate portion near the contact surface melts.

Figure 6 shows the portion of the aluminum (alloy) plate blank 11 that is to become the opposing surface of the mating portion (including the neighboring portion).
This figure shows an example of a method and apparatus for locally forming an anodic oxide film only on 11a. 12 and 1
Reference numeral 3 denotes a support for the blank 11, in which a shaft 13aQ fixed to the support 13 is inserted through the through hole 12a of the support 12, and the support 13 is hinged to the support 12 so that the , the blank 11 is held between supports 12 and 13 by a suppressing mechanism (not shown). Supports 12 and 13
Seal members 14 and 15 made of an elastic material such as elastic rubber are attached to the lower end portions of the blank 11, respectively. A stepped portion 15a is formed. Further, the sealing member 14 is configured such that the blank portion 11a can be exposed.
14 m of the lower surface is arranged. In addition, 16 is an electrolytic cell,
17 is an electrolytic solution, and 18 is a cathode.

The blank 11 held between the supports 12.13 is placed in the electrolytic cell 16 such that at least the portion 11a is immersed in the electrolyte 17 and the portion tla faces the cathode 18 at a predetermined distance. Enter. Next, the support 12 (or the support 13) is connected to a positive voltage source and anodized by a known method, thereby forming an anodic oxide coating (not shown) only on the surface of the portion 11a. ) can be formed. In this case, since the sealing members 14 and 15 provide a tight seal, the electrolytic solution 17 will not penetrate onto the surface of the blank 11 other than the portion 11a.

FIG. 7, FIG. 8, and FIG. 9 show a portion 11a of a plurality of blanks 11 (five in the figure, but tens of blanks are also possible).
Above is an example of a method and apparatus for locally forming an anodic oxide film. Reference numeral 20 denotes a jig, on which a step portion 20a is formed, which has a width equal to the width W of the portion 11a, a height equal to the thickness t of the blank 11, and a number of steps equal to the number of blanks 11. Furthermore, a recess 20b for inserting the support 21 is formed in connection with the lowermost stage of the staircase 20a. As shown in Figure 8,
A plurality of blanks 11, each portion 11a having a staircase portion 20
After stacking the jig 20 and the support 20b so as to contact the horizontal part 208' of
1a so as to cover the opposite side, and both ends of the support body 22 and the support body 21. The laminated blank IIA consisting of a plurality of blanks 11 is fastened to the support member 23.
and hold it in place at 21.

The laminated blank IIA is then removed from the jig 20 together with the supports 21, 22 (consisting of electrical insulators) and placed into the electrolyte 25 in the electrolytic cell 24, as shown in FIG.
The laminated blank IIA is immersed so that it is at a predetermined distance from the cathode 26 (therefore, the cathode 26 is disposed diagonally in the figure), the laminated blank IIA is connected to a positive voltage source, and anodization is performed. In this case, not only the portion 11a but also the blank cut edge 1
An anodic oxide film is also formed on 1f, but the cut edge l
The anodic oxide film formed on lf has almost no effect on pine seam resistance welding. In this case, the anodic oxide film will exist on the interface edges 1b' and l'b' in Fig. 2, but since the degree of deformation of the metal is extremely large in this part, the crack area of the anodic oxide film will be small. It is presumed that this is because it also becomes very large.

It goes without saying that the above method can also be applied to the formation of a chemical oxide film or other electrically insulating film on the portion 11a.

The pressure applied during matshu seam resistance welding varies depending on the electrode structure and the width of the overlapping part, but is usually about 35 to 150.
is preferably within the range of 9.

If the weight is less than about 35 kg, the amount of mush will decrease and splash will easily occur, while if it exceeds about 150 kg, troubles such as bending and deformation of the electrode will easily occur. The mating amount is preferably in a range such that the thickness of the welded portion is 1.0t to t8t (t=thickness of the aluminum alloy plate).

In the matshu seam resistance welding method of aluminum (alloy) plates according to the present invention, an electrically insulating film having predetermined properties is closely formed on each of the opposing surfaces of the overlapping part, so that the welding part is not adversely affected. It has the effect that it is possible to obtain a mash seam resistance welded part with excellent welding strength and airtightness without generating splash.

Examples will be described below.

Example 1 A commercially available A3004p alloy plate with a thickness of 0.30 m (hardness H
19) was cut into cracks with a width of 40 m and a length of 100 cm. The bath temperature was applied to only one side of the blank over a width of 5 m from one end edge in the length direction of the blank using the means and equipment shown in Fig. 6 under the conditions of A/dm% voltage of 19 V. When the treatment was carried out for 3 minutes while maintaining the temperature at 20° C., an anodic oxide film having a thickness of 1 μm was formed on only one side over a width of 5 cm from the edge of the blank.

Prepare two pieces of the anodic oxide coating,
The two blanks were stacked so that the anodized coating surfaces faced each other and were in contact. The overlap width is 0.6
■It was. The overlapping part of the overlapping blanks,
Matsushi seam resistance welding was performed using a welding device having a pair of opposing roll electrodes and wire electrodes. At that time, the diameters of the roll electrodes used were 80 m and 200 mm, and the wire electrodes were made of electrically soft copper wire with a diameter of 1.5 m and a width of 2 mm.
．． A piece rolled into 10 flat pieces was used.

Welding was carried out using a 50 Hz AC power source as a welding power source, a welding force of 65 mm, and a welding speed of 8 m/min.

As a result, 4.7 to 5. In the welding current range of OkA,
Good welding was possible, and a welded part with excellent welding strength and airtightness and without molten splash could be obtained. Table 1 shows the conditions of the welded parts. Welding current is 5. Exceeding OkA will likely cause molten metal splash or damage to the weld surface.
On the other hand, when the current was less than 4.6 kA, the strength and airtightness of the common joint were found to be poor in practical terms.

Figure 3 shows the microscopic structure of a cross section perpendicular to the welding direction of the obtained weld, and Figure 4 shows the microscopic structure of a cross section parallel to the welding direction near the center of the weld (magnification: 40.7.6 % hydrochloric acid - 46.2% thifutic acid aqueous solution), as is clear from the photograph in Figure 3, there is molten nada, T5 ( It can be seen that the molten nugget did not reach both ends of the overlapping surfaces and the surface of the welded part. The width of the molten nugget in this case is 1.7 times the blank plate thickness. Furthermore, as is clear from the photograph in Figure 4, molten nuggets are formed continuously in the welding direction, and the presence of such molten nuggets ensures that the strength and airtightness of the weld are sufficiently maintained. You can see that it is sagging.

Example 2 Using the same A3004p alloy plate and the same anodizing treatment method as in Example 1, the anodic oxide film was formed by changing the treatment time.
Blanks having a thickness of μm and 0.3 μm were prepared. The blank was subjected to pine seam resistance welding using the same welding equipment as in Example 1 and under the same welding conditions.

As a result, when the thickness of the anodic oxide film was 0.3 μm, some molten splash occurred in the obtained weld, but the strength and airtightness of the weld were at a sufficient level. In that case, the welding current range that can be welded is 5
．． 5 kA to 5.9 kA, welding current 5.5
Below kA, the welding strength decreases significantly, and
, and when the temperature exceeded 9 kA, significant melt splash occurred.

When the thickness of the anodic oxide film was 3 μm, it was possible to obtain aged joints with no melt splash and excellent welding strength and airtightness. The usable welding current range was 4.6 to 4.7 kA, which tended to be somewhat narrower than in Example 1.

The results are shown in Table 1.

Example 3 A3003p alloy plate with a plate thickness of 0.30 days (hardness H18)
A blank with a width of 40 cm and a length of 100 cm was made from the blank, and an anodic oxide film with a thickness of 1 μm was formed on only one side over a width of 5 mm from the edge of the blank using the same method as in Example 1. .

The blank was processed using the same equipment and means as in Example 1.
Matsushi seam resistance welding was performed. As for the welding conditions, the welding force is 52kl? The welding speed was 8 m/min.

As a result, in the welding current range of 4.9 to 5.1 kA,
It was possible to obtain a welded part in which good welding was possible, the welding strength and airtightness were at a sufficient level, and there was no occurrence of molten splash.

The results are shown in Table 1.

Example 4 A3052p alloy plate with a thickness of 0.30 m+ (hardness H38
) and A30829 alloy plate (hardness H39) with a thickness of 0.32+m to make a blank with a width of 40cm and a length of 100m, and an anodic oxide film with a thickness of 1μm was applied using the same method as in Example 1. was formed on only one side over a width of 5 mm from the edge of the blank.

Matsushi seam resistance welding was performed using the same equipment and means as in Example 1, with the overlapping width of the blanks set to 0.4 m. Although some molten splash occurred in the weld under the welding conditions, a weld with sufficient strength and airtightness was obtained. In that case,
The welding current range that can be welded is 4.4 for A3052p alloy.
~4.7 kA, 4.3-4. for A3082p alloy.
It was 5 kA. When the upper limit of the current amount was exceeded, the occurrence of molten splash was significant, and on the other hand, when the current amount was below the lower limit, the welding strength was significantly reduced.

The results are shown in Table 1.

Example 5 A commercially available A3004p alloy plate with a thickness of 0.39W (hardness H
19) was cut into blanks with a width of 40 cm and a length of 100 cm. A set of 6 blanks was fixed using the means shown in Fig. 8 so that only one side of each blank was exposed by 2 cm from the edge of the blank, and the exposed surface of the group of blanks was set to 0. 1 containing .54 ammonia
When immersed in hot water at 00℃ for 20 minutes, the film thickness was 1μm.
An aluminum oxide film (boehmite film) was formed on only one side of the blank over an edge of the blank and a width of 2 m from the edge.

The blank was subjected to pine seam resistance welding using the same equipment as in Example 1 and under the same welding conditions.

As a result, in the welding current range of 4.6 to 5.0 kA,
This furnace enables good welding, and produces welded parts with excellent welding strength and airtightness, and without the occurrence of scorching.

Table 1 shows the conditions of the welded parts.

Example 6 A commercially available A3004p alloy plate with a thickness of 0.30cm (hardness H
19) was cut into blanks with a width of 40 tm and a length of 100 cm. Spread 2% (by weight) of alumina powder with a particle size of 0.5 μm or less on only one side of the blank over a width of approximately 10 mm from one edge in the length direction of the blank.
The sample was dried by heating for 10 minutes in 5% (by weight) sodium silicate containing alumina powder to form a sodium silicate film containing alumina powder with an average thickness of 1.5 μm.

Two blanks coated with the sodium silicate film were prepared, and the two blanks were stacked on top of each other so that the coated surfaces faced each other. The overlap width was 0.6 square meters.

The overlapped portions of the stacked blanks were subjected to pine seam resistance welding using the same equipment as in Example 1.

Welding was performed using a 50 Hz AC power source as a welding power source, a welding force of 52 kg, and a welding speed of 8 m/min.

As a result, although a slight amount of molten splash occurred, it was possible to obtain a welded part whose strength and airtightness were at a sufficient level.

In that case, the welding current range that can be welded is 4.65 kA ~
When the welding current is less than 4.65 kA at 4 or 8 kA, the welding strength decreases significantly;
If it exceeded kA, welding could not be performed because the occurrence of molten streak rush became significant.

Figure 10 shows the microscopic structure of the obtained weld in a cross section perpendicular to the welding direction (magnification: 40.7.6% hydrochloric acid-46.2
% hydrofluoric acid aqueous solution). As is clear from the photograph in Figure 10, molten nuggets are uniformly formed along the overlapping surfaces of the welded parts, and molten nuggets are formed at both ends of the overlapping surfaces.
Melting streak rush is occurring. In this case, it can be seen that although molten scorch occurs, the welding strength and airtightness of the nuggets are maintained at a sufficient level due to the presence of the molten nuggets.

The results are shown in Table 1.

Comparative Example 1 Commercially available A3004p alloy plate with a thickness of 0.30 (hardness H
19) into a blank with a width of 40 m and a length of 100 m, and cut the blank into 401/4 as shown in Figure 6.
5) When immersed in the liquid for 30 seconds, a film was formed due to the temperature of the liquid.

Two blanks were prepared, and the two blanks were placed one on top of the other so that the treated coating surfaces faced each other. The overlapping width was 0.6 m. The overlapped portions of the stacked blanks were subjected to pine seam resistance welding using the same equipment as in Example 1. At that time, the welding pressure was 64k19,
The welding speed was 8 m/min.

As a result, as the welding current was increased, the occurrence of molten streak rush became more significant, but the welding strength or airtightness of the weld did not reach a sufficient level, making it impossible to obtain a good weld. .

Figure 11 shows the microscopic structure of a cross-section perpendicular to the welding direction of the weld obtained when the welding current was 5.4 kA (magnification 40.7.6 dihydrochloric acid-46.2% hydrofluoric acid aqueous solution). corrosion). As is clear from the photograph in FIG. 11, molten nuggets are formed at both ends of the overlapping surfaces of the welded portion, and molten splash is generated from the molten nuggets.

On the other hand, it can be seen that the welding strength and airtightness of the intermediate portion of the overlapping surfaces did not reach a sufficient level.

The results are shown in Table 1.

Comparative Example 2 A30049 alloy plate with a plate thickness of 0.30 mm (hardness H19)
were prepared, and without coating the overlapping and facing surfaces to be welded with an electrically insulating film, matush seam resistance welding was performed using the same welding equipment as in Example 1.

At this time, the overlapping width is set to 0.6 cm, and the welding pressure is set to 4
Welding was carried out at 5 o'clock and 65 o'clock and at a welding speed of 8 rrV/min.

As a result, when the welding force was 65 kg, the welded overlapping part was crushed considerably, but the temperature rise at the overlapping surface was low, and the welding current was reduced to 7.5 k.
Even if up to A was added, no bonding occurred at all.

When the welding force is 45kg, the welding current is 6.0k.
Although molten splash occurred in sample A, the welding strength was significantly inferior. When this welded part was peeled off and one overlapping surface of the welded part was observed, the 11th
Similar to the result shown in the photograph in the figure, the amount of heat generated at the overlapping surfaces during welding is significantly large at both phosphorus parts of the overlapping surfaces of ±.
The center portion was significantly smaller, and the strength and airtightness of the welded portion were significantly inferior.

Note: (1) Based on eddy current measurement method (product name of measurement device: Dermitron).

(2) When welding under optimal welding conditions.

(3) The welding strength is as shown in Fig. 12.
The judgment was made by holding down one blank part 41 in the vicinity, grasping the other blank part 42 in the vicinity of the welded part 40 with pliers, and pulling it up in the direction of the arrow to tear the welded part 40 and evaluating the cutting state.

◎...Cut along the side edge 408 of the welded part 40 (
Fig. 12(a)) ○...The cut surface 43 slightly includes the weld interface 44 (corresponding to the overlapping surface before welding) (Fig. 12(b)) Δ...The cut surface 43 slightly includes the weld interface 44 (corresponding to the overlapping surface before welding) Includes a welded part interface 44 (Fig. 12(C)) X... Cutted at the welded part interface 44 (Fig.
d)) (4) For airtightness, use a commercially available dye tester (trade name: RED-MA).
RK) was used.

◎...No reaction at all with the flaw detection agent, ○...Slight local reaction with the flaw detection agent, ×...
Reaction occurred on the entire surface with flaw detection agent, (5) ◎...No occurrence, ○...Slight occurrence, △...
Slight occurrence, X: Significant occurrence

[Brief explanation of drawings]

FIG. 1 is an explanatory longitudinal cross-sectional view of the vicinity of the overlapped portion before welding by the method of the present invention, and FIG. 2 is an explanatory longitudinal cross-section showing the state of the overlapped portion of FIG. 1 after matush seam resistance welding. Figure 3 is a cross-sectional micrograph of an example of a welded area obtained by the method of the present invention, viewed from a direction perpendicular to the weld line, and Figure 4 is a cross-sectional micrograph of an example of a welded area obtained by the method of the present invention. A cross-sectional micrograph viewed from a parallel direction, FIG. 5 is an explanatory longitudinal cross-sectional view of another example of the vicinity of the overlapping portion before welding by the method of the present invention, and FIG. 6 is a diagram of an apparatus for forming an electrically insulating film. FIG. 7 is a partially cutaway perspective view of Example 1, and FIG.
FIG. 8 is a vertical sectional view taken along the line ■-■ in FIG. 7, FIG. 9 is a vertical sectional view of the device of the second example, and FIG. FIG. 11 is a cross-sectional micrograph of another example of a welded part made by the method of the present invention, viewed from a direction perpendicular to the weld line; FIG. Fig. 12 is a perspective view showing the welding strength test method, Fig. 12(a) shows the welding strength is excellent, Fig. 12(b) shows the welding strength is good, and Fig. 12(b) shows the welding strength test method.
Figure 2 (,) shows a defective one, and Figure 12 (d) shows a significantly defective one. 1.1'... Aluminum (alloy) plate, 2... Overlapping portion, 3... Upper roller electrode, 3'... Lower roller electrode, la, l'a... Opposing surface , 4... Electrical insulating film, 7... Cracks. Ward Ward 1 sun ■ Shinku Ward 40 - School Section Figure 5 Figure 6 Figure 7 r ■ Figure 8 (C) (d) Procedural amendment (method,) Month 27, 1980 Commissioner of the Patent Office Shimada Haruki-dono / Case indication Showa J Otsu year patent application No. 123022 2 Name of the invention Resistance welding method 3 Person making the amendment Relationship to the case Patent applicant Yokohama Shikanaza ν Ririkiki Mariacho Address 236 Yokohama, Kanagawa Prefecture 1ll Kamaritani-cho, Kanazawa-ku, City
No. 13-2 Osamu Otohisa 10S Address 2-1-j Shibadaimon, Minato-ku, Tokyo I10'1 Telephone 03-1137-/11r9 "Brief explanation of one drawing of the specification subject to amendment B" column and Drawing 7, contents of amendment (1) "Indicates metallographic structure" is added next to "ta" on page 37, line 72 of the specification. (2) On page 37, line 73, add ``indicates metal structure'' next to ``viewed from...''. (3) In the second line of page 32, next to "viewed from... direction", add "indicates metal structure". (4) Add "indicates metallographic structure" next to "viewed from... direction" on page 32, line q. (5) Correct Figure 7.2 (Q) and (d) as shown in the attached sheet. #12 circles (C) (d)

Claims (3)

[Claims] (1) In a method of mating seam resistance welding of the overlapping portion of aluminum plates or aluminum alloy plates between opposing electrodes, each of the opposing surfaces of the overlapping portion of the aluminum plate or aluminum alloy plate includes: Matushu seam resistance welding is a method of welding aluminum alloy plates with a very thin electrically insulating film that produces minute cracks due to the deformation of the metal during welding. (2) The extremely thin electrically insulating film has a thickness of O11 to 5.0
2. The method for welding an aluminum plate or an aluminum alloy plate according to claim 1, wherein the anodized coating is mainly composed of aluminum oxide. (3) The extremely thin electrically insulating film has a thickness of 0.1 to 5
．． 2. The method of matshu seam resistance welding of an aluminum plate or aluminum alloy plate according to claim 1, wherein the chemical oxide film is a chemical oxide film mainly composed of 0- aluminum oxide.