JPH0810962A - Spot welding method of multilayered metal sheet and production of automobile door - Google Patents

Abstract

PURPOSE:To provide the spot welding method capable of surely obtaining the required welding strength with applying appropriate pressure force when a metal sheet piled with three sheet or more is welded by spot welding. CONSTITUTION:In the spot welding to weld a multilayered metal sheet piled with three sheets or more of metal plate, the prescribed metal sheet 14 among layered medial sheets 11-14 is connected to a ground 20, between a second and third metal sheet 12, 13 from the top layer side and/or a second and between any metal sheets 17, 18 lower than thereof, small protrusion 12a are provided. The electrode 7, which is placed on the same axis line L as the small protrusion, is abutted on the top layer metal sheet 11, while the prescribed pressure force is applied on metal sheets, electric current is caused to flow between the electrode and ground 20, each metal sheet is welded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for spot-welding and joining multiple metal plates formed by stacking three or more metal plates, which is particularly high even when the number of metal plates to be stacked is increased. The present invention relates to a spot welding method for a multiple metal plate that can be welded at a welding strength and can obtain a product excellent in appearance without indentation or distortion.

[0002]

2. Description of the Related Art Generally, in order to weld and join a plurality of stacked metal plates by a spot welding method such as indirect spot welding, an earth is connected to the lowermost metal plate and the tip of the electrode is connected to the uppermost layer. This is carried out by bringing the metal plate into contact with the surface of the metal plate and applying a predetermined pressurizing force, and passing a large current of several thousand amperes between the electrode and the ground.

[0003]

By the way, in the spot welding method described above, when a multiple metal plate formed by stacking three or more metal plates is welded, the reactive current becomes larger toward the lower metal plate and the welding strength increases. There is a problem that When performing spot welding, it is common to provide a support member that supports the metal plate on the same axis as the electrode, but this support member is provided on the same axis as the electrode depending on the welding site. It may not be possible. In such a case, when the metal plate is pressed to perform spot welding, the metal plate is bent, and there is a problem that the adhesion strength of each metal plate is reduced and the welding strength is relatively reduced. When a metal plate is pressed with an excessive force, there are problems that indentations are generated on the surface of the metal plate to make it look unattractive, and permanent distortion remains in soft metal such as aluminum. Therefore, when the number of metal plates to be overlapped increases, the required welding strength and good-looking appearance quality cannot be obtained even if various conditions such as pressurizing pressure, current magnitude, and energization time are optimally set. It was difficult.

The present invention has been made in view of the above problems, and it is possible to increase the welding strength of multiple metal plates by a simple method, and it is not possible to provide a supporting member on the same axis as the electrode. Even in such cases, spot welding of multiple metal plates can be performed, in which it is easy to select various conditions such as pressure applied to the electrode, energization time, and magnitude of current, and products with high welding strength and appearance can be obtained. A method and a method of manufacturing an automobile door are provided.

[0005]

To solve the above problems, the applicant of the present application has taken the following measures. That is,
The first welding means, in a spot welding method of welding three or more superposed multiple metal plates by spot welding, connects a ground to a predetermined metal plate among the superposed metal plates, and from the uppermost layer side. Small protrusions are provided between the second and third metal plates and / or between any lower metal plates, and the electrodes arranged on the same axis as the small protrusions are brought into contact with the uppermost metal plate, The metal plates are welded to each other by applying an electric current between the electrodes and the ground while pressurizing the metal plates with a predetermined pressurizing pressure.

The second welding means is the same as the first welding means described above, wherein a plurality of the small projections are provided between the metal plates by shifting the position and the layer of the metal plate, and the electrodes are arranged on the same axis as the small projections. It is arranged such that an electric current is passed between the electrode and the ground to weld and join the small projections. The third welding means, in addition to the first electrode arranged on the same axis as the small protrusion in the first or second welding means, has a second electrode at a position separated from the axis of the small protrusion. They are arranged so that welding is performed by sequentially passing an electric current between the first electrode and the second electrode and the ground. Further, any one of the above-mentioned first to third welding means is selectively or appropriately applied to a method for manufacturing an automobile door in which each of an outer panel, a door sash, and a metal plate sandwiched therebetween is weld-joined by spot welding. It is also possible to apply in combination with.

[0007]

[Function] When an electric current is passed between the electrode and the ground, which are arranged on the same axis as the small protrusion, the current flows intensively through the small protrusion, and the welding strength of the portion provided with the small protrusion is increased. . The effect of providing the small protrusions is greater on the lower layer side of the multiple metal plate in which the reactive current increases. Therefore, like the second welding means of the present invention, by providing one or a plurality of small protrusions in any layer between the metal plates, the welding strength of the multiple metal plates can be partially or wholly. Can be increased. According to the third means of the present invention, not only between the metal plates provided with small protrusions, but also between the uppermost metal plate and the metal plate below it are firmly welded by ordinary spot welding,
The welding strength of the entire multi-layer metal plate can be further increased. Further, in the automobile door manufactured by the above spot welding method, the outer panel, the door sash, and the metal plate sandwiched therebetween are firmly welded and joined,
It is possible to obtain an automobile door having excellent appearance without dents or distortions.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Spots according to the present invention will be described below with reference to the drawings.
Welding method and automobile to which this spot welding method is applied
An example of a door manufacturing method will be described. Figure 1 shows the first welding
According to the embodiment of the means, (A) shows the state before welding and joining,
(B) shows the state after welding and joining. In FIG.
Reference numeral 6 is a support member, reference numeral S ₁, S₂Painted in black
The filled circles indicate welded joints, and the black circles (S₁,
S ₂) Indicates the relative strength of the weld joint strength.
ing. The metal plates 3, 4, which are placed on the support member 6,
The metal plate 5 in the lowermost layer of 5 has a circle toward the metal plate 4 in the middle.
Small protrusions 5a having a shape are formed, and their tips are the intermediate layer.
Is in contact with the surface of the metal plate 4. That is, the welding site
In the above, the uppermost metal plate 3 and the intermediate metal plate 4 are
Although in surface contact, the metal plate 4 of the middle layer and the gold of the bottom layer
The small plate 5a is in point contact with the metal plate 5
Is. The small protrusions 5a are not limited to circular shapes, but oval shapes and beads.
Shape.

Next, the electrode 7 is arranged on the outer surface of the metal plate 3. At this time, the electrode 7 is positioned so as to be on the same axis L as the small protrusion 5a, and the tip is brought into contact with the outer surface of the metal plate 3. The ground 20 is connected to the lowermost metal plate 5. In this state, when a predetermined pressing force (for example, 45 Kgf) is applied to the electrode 7 and a predetermined amount of current (for example, 7000 A) is flown between the electrode 7 and the earth 20 for a predetermined time (for example, cycle time 8 Hz), The electric current intensively flows through the small protrusions 5a, the small protrusions 5a are melted, and the metal plate 5 and the metal plate 4 are welded and joined. Further, since a current also flows between the metal plate 3 and the metal plate 4 which are in surface contact with each other, welding is performed during this time. In this case, the welded joint S _{1 formed} by the small protrusions 5a is welded and bonded with a higher strength than the welded joint S ₂ . The small projections 5a described above may be formed on the metal plate 4 of the intermediate layer toward the metal plate 5 of the lowermost layer.

FIG. 2 shows another embodiment of the first welding means. In the embodiment shown in (a) and (b),
(A) shows the state before welding and joining, and (B) shows the state after welding and joining. In the embodiment shown in (a), one small projection is provided between the second and third metal plates 12 and 13 from the uppermost layer among the four metal plates 11, 12, 13, and 14 that are stacked. 12a is provided. Further, in the embodiment shown in (b), one small protrusion 17a is provided between the lowermost metal plate 18 of the four metal plates 15, 16, 17 and 18 and the metal plate 17 above it. Is provided. Small protrusions 12a, 17a
Is the same as in the previous embodiment that it may be formed on either the metal plates 12, 13 or the metal plates 17, 18.

Also in this embodiment, the lowermost metal plate 1 is used.
The earth 20 is connected to 4, 18 and the small protrusions 12a, 17a
The electrode 7 is arranged on the same axis L as. Then, when a current of a predetermined magnitude is applied between the electrode 7 and the ground 20 at a predetermined pressurizing pressure for a predetermined time, a gap between the metal plates 12 and 13 having the small protrusions 12a and 17a is formed ((a)). The welded joint S _{3 of the} embodiment shown) or the welded joint S ₆ between the metal plates 17 and 18 (the embodiment shown in (b)) is welded most strongly. Also in the embodiments shown in (a) and (b), since the current flows between the metal plates in the surface contact state, the metal plate 1
1 and 12 and between the metal plates 13 and 14 (the example of (a)), between the metal plates 15 and 16 and between the metal plates 16 and 17 (the example of (b)), weld bonding (weld joint S ₄ , S
₅ , S ₇ , S ₈ ) are performed.

FIG. 3 is an explanatory view for spot welding an automobile door by the second welding means of the present invention.
Shows the state before welding and joining, and (B) shows the state after welding and joining. FIG. 5 is a cross-sectional view showing the structure of the belt line 31 according to an explanatory view of the rear door of the automobile. As shown in the figure, the belt line 31 has a three-layer structure in which a reinforcement 34, which is another metal plate, is sandwiched between the door sash 32 and the outer panel 33.
The door sash 32, the outer panel 33, and the reinforcement 34 are welded and joined by spot welding. Reference numeral 35 in FIG. 5 is an inner panel. By the way, the door sash 32, the outer panel 33, and the reinforcement 34 of the rear door as shown in FIG.
When spot welding is performed on the inner panel 35,
Since the gap between the door sash 32 and the door sash 32 is narrow, it may be difficult to provide the support member on the same axis as the electrode.
Therefore, in the embodiment shown in FIG. 3, the support member 19 is provided at a position slightly apart from the welded portion. In addition, the reinforcement 34 and the door sash 32 are separated from the welded portion by a jig (not shown) at the outer panel 3
It is fixed to 3.

In this embodiment, a small protrusion 32a is formed on the door sash 32, which is the lowermost metal plate, toward the reinforcement 34 so that the door sash 32 and the reinforcement 34 are partially in point contact with each other. . And
The first electrode 7 is placed in contact with the surface of the outer panel 33 on the axis L ₁ of the small protrusion 32a. The second electrode 8 is located apart from the axis L ₁ of the small protrusion 32a, and the outer panel 33, the reinforcement 34, and the door sash 32 are all in surface contact with each other (position indicated by axis L ₂ ). Of the outer panel 33. In order to reduce the reactive current as much as possible, it is desirable that the ground 20 be connected as close as possible to the small protrusion 32a where the door sash 32 and the reinforcement 34 are in point contact with each other.

In this state, whichever of the electrodes 7 and 8 may come first, first, a current is passed between the second electrode 8 and the ground 20 to perform welding. Then, welding is performed by passing an electric current between the first electrode 7 and the ground 20. By passing a current between the first electrode 7 and the ground 20, a door sash 32 and reinforcement 34 intensively large current flows through the small projection 32a is firmly joined at weld joint S _12, the The outer panel 33 and the reinforcement 34 by applying a current between the second electrode 8 and the ground 20.
And the reinforcement 34 and the door sash 32 are joined at the respective welded joints S ₉ , S ₁₀ . Of course, on the first electrode 7 side, the reinforcement 3 through which an electric current flows
Although welding is also performed at the welded joint S ₁₁ between the outer panel 4 and the outer panel 33, its strength is smaller than that of the welded joint S _{12 for} the same reason as above.

FIG. 4 illustrates a third welding means of the present invention. (A) shows a state before welding and joining, and (B) shows a state after welding and joining. In this embodiment, a plurality of small protrusions are provided by shifting the positions of the small protrusions and the layer of the metal plate. That is, the metal plates 21 and 2 that are overlapped
Of the 2, 23, 24, the small protrusion 21a is provided between the uppermost metal plate 21 and the second metal plate 22, and the second metal plate 2 is provided.
Small projections 22a are provided between the second and third metal plates 23, and small projections 23a are provided between the lowermost metal plate 24 and the metal plate 23 immediately above it, with their positions offset. Electrodes 7, 9, 1
In the state of being brought into contact with the uppermost metal plate 21, 0 is arranged coaxially with the axes L ₁ , L ₂ and L _{3 of the} small protrusions 21a, 22a and 23a. It does not matter which electrode is performed first, but in the figure, the electrode 7 on the left side to the electrodes 9, 10
Welding is performed by sequentially applying a current to. Each electrode 7, 9, 10
At the site provided, small protrusions 21a, 22a, since it is most firmly welded in the weld joint S _13, S _14, S ₁₅ having a 23a, thereby entirety firmly welded in multiple metal plate Will be done. In this embodiment, the small protrusion 21a is not provided between the uppermost metal plate 21 and the second metal plate 22, and the metal plates 21 and 22 may be subjected to normal spot welding. Good.

As described above, even if the number of metal plates to be overlapped increases, the welding strength of multiple metal plates can be partially or wholly adjusted by appropriately combining the first to third welding means. Can be increased to In the above-mentioned embodiment, the earth is connected to the lowermost metal plate of the multiple metal plates formed by stacking a plurality of sheets, but the welding joint connects the metal plate with which the electrodes are brought into contact with the earth. Since it is performed with a metal plate, when attempting to weld-bond any metal plate among the stacked metal plates, the metal located in the lowest layer of the metal plates to be weld-bonded Just connect the ground to the board.

[0017]

As described above, according to the present invention,
Even in the case of spot welding a multi-metal plate formed by stacking three or more metal plates, the metal plates of the multi-metal plate can be firmly or partially welded together. Also, even if the number of stacked metal plates increases,
Since no special welding technique is required, it is useful for shortening the work time and the work load, and it is possible to reduce the cost and stabilize the quality in spot welding of multiple metal plates.
Further, even when the supporting member cannot be provided on the same axis as the electrode, the welding strength can be increased without increasing the pressure applied to the electrode, so that the indentation on the surface of the metal plate due to the excessive pressing force can be achieved. Alternatively, it is possible to prevent deformation due to bending of the metal plate, and it is possible to obtain a product of excellent quality with excellent appearance. Therefore, by applying such a spot welding method to the manufacture of automobile doors, it is possible to obtain automobile doors that are inexpensive and have excellent appearance.

[Brief description of drawings]

1 relates to an embodiment of the first welding means of the present invention,
(A) shows a state before welding and joining, and (B) shows a state after welding and joining.

FIG. 2 relates to another embodiment of the first welding means of the present invention, where (a) is a case where a small protrusion is provided between the second and third metal plates, and (b) is the bottom metal layer. When a small protrusion is provided between the plate and the metal plate above it, in each case (A)
Shows the state before welding and joining, and (B) shows the state after welding and joining.

FIG. 3 relates to an embodiment in which the second welding means of the present invention is applied to an automobile door, (A) is a sectional view showing a state before welding and joining, and (B) shows a state after welding and joining. is there.

FIG. 4 relates to an embodiment of a third welding means of the present invention,
(A) is a sectional view showing a state before welding and joining, and (B) shows a state after welding and joining.

FIG. 5 is a partial enlarged view showing an example of a belt line of an automobile door according to an example of a multiple metal plate.

[Explanation of symbols]

3,4,5 Metal plate 6,19 Support member 7,8,9,10 Electrode 11-18 Metal plate 20 Earth 21-24 Metal plate 31 Belt line 32 Door sash 33 Outer panel 34 Reinforcement S ₁ -S ₁₅ Welding connection Part L, L _{1 to} L ₃ axis

Claims (4)

[Claims] 1. A spot welding method for spot welding a multiple metal plate, which is formed by stacking three or more metal plates, by connecting a ground to a predetermined metal plate among the stacked metal plates, Small protrusions are provided between the second and third metal plates from the upper layer side and / or between arbitrary metal plates in the lower layer, and the electrodes arranged on the same axis as the small protrusions are provided on the uppermost metal plate. A spot welding method for multiple metal plates, wherein the metal plates are welded to each other by abutting them and applying a current between the electrode and the ground while pressurizing the metal plates with a predetermined pressurizing pressure. . 2. The spot welding method for a multiple metal plate according to claim 1, wherein a plurality of the small protrusions are provided between the metal plates by shifting the positions and the layers of the metal plates, and the electrodes are arranged on the same axis as the small protrusions. Is arranged, and a current is passed between the electrode and the ground so that the small protrusions are welded and joined to each other. 3. The spot welding method for a multiple metal plate according to claim 1, wherein, in addition to the first electrode arranged on the same axis as the small projection, the axis of the small projection is provided. A second electrode at a position spaced from
A spot welding method for a multiple metal plate, wherein a welding current is sequentially applied between the electrode and the second electrode and the ground to perform welding joining. 4. A method of manufacturing an automobile door in which one or a plurality of metal plates are sandwiched between an outer panel and a door sash, and these are weld-joined by spot welding, a ground is connected to the outer panel or the door sash,
A small protrusion is provided on any one of the outer panel and the metal plate, the metal plate and the metal plate, or the metal plate and the door sash, and the electrode is arranged on the same axis as the small protrusion, and the electrode is brought into contact with the door sash or the outer panel. Then, a current is caused to flow between the electrode and the ground, and the outer panel, the door sash, and the metal plate are welded and joined to each other.