JPH09220673A - Metal sheet weld joining structure and metal sheet weld joining method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily weld a thin metal sheet of a body panel of an automobile, etc., with well appearance at a low cost about the weld joining structure of the metal sheet suitably used on the weld part of the body panel of the automobile as well as a place to be welded with good appearance. SOLUTION: In a weld joining structure between a 1st metal sheet 10 and a 2nd metal sheet 20, a part 30 subjected to hemming where the edge periphery 11 of the 1st metal sheet 10 is folded toward the 2nd metal sheet 20 side is formed on the welding part of the 1st metal sheet 10, the part 30 and the metal sheet 20 are lapped, the part between the folded edge periphery 11 of the 1st metal sheet 10 and the 2nd metal sheet 20 at the lapped part is welded and joined.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a welded joint structure and a welded joint method for a sheet metal, which is suitable for use in a portion such as a joint portion of a body panel of an automobile where the sheet metal should be joined in good appearance.

[0002]

2. Description of the Related Art Conventionally, the body of an automobile is formed by joining various body panels, and there are various welded joints. For example, FIGS. 16 to 18 show an example of a conventional vehicle body panel coupling structure.
Is a schematic perspective view and a schematic exploded perspective view of an automobile body showing the connection structure, and FIG. 17 is a partially cutaway perspective view showing a superposed state of the body panel (a broken surface is a BB line in FIG. 16).
FIG. 18 is a partially cutaway perspective view (corresponding to FIG. 17) for explaining the joining operation of the body panels.

In these examples of the joint structure shown in FIGS. 16 to 18, first, the edge portions of the outer panel such as the side body 110 are subjected to step processing corresponding to the plate thickness so that the inner panel such as the roof panel 111 is processed. By overlapping the edge portions, the surfaces of the outer panel and the inner panel are flush with each other, as shown in FIG. Then, spot welding is performed in the vicinity of the edge of the roof panel 111, but distortion occurs on the surface of the roof panel 111 due to the spot welding, and a good appearance cannot be obtained.

Therefore, as shown in FIG. 18, a brazing is applied between the stepped portion of the outer panel and the edge of the inner panel to hide the lower edge of the roof panel 111 and the distortion caused by spot welding. Processing is performed. Further, as shown in FIG.
By carrying out a grinding operation so as to be flush with each panel for No. 2, a flat grinding finish 113 is formed as shown in the drawing.

Further, with respect to the brazed portion 112, a process of hiding the joint portion by a molding is also used.
This kind of work is performed because if the lower end edge on the roof panel 111 side is exposed, there is an edge, which is unattractive, and it is necessary to process the edge in the sense of preventing rust. Of.

On the other hand, FIGS. 19 and 20 show another example of a conventional vehicle body panel connection structure (an example of a so-called Mohican type roof connection structure), and FIG. 19 shows an automobile connection structure. 20 is a schematic perspective view and a schematic exploded perspective view of the vehicle body, and FIG. 20 is a partially cutaway perspective view showing a joint structure of the body panel (a broken surface corresponds to a cross section taken along the line CC in FIG. 19). .

As shown in FIGS. 19 and 20, in a so-called Mohican type roof structure, a groove portion 114 extending in the vehicle length direction is composed of a roof panel 111 and a side body 110. In such a structure, the roof panel 111 and the side body 110 are joined by spot welding in the groove portion 114 by utilizing the structural characteristics.

Therefore, unlike the above-mentioned structure, the work of grinding and finishing 113 of the brazing portion 112 is unnecessary, but the side body 110 has a plurality of panel portions 110A, 110A.
In many cases, it is formed separately in 110B. In this case, the brazing 112 and the grinding finish 113 thereof are indispensable as shown in FIGS.

[0009]

However, the conventional mounting structure as described above has the following problems. That is, in the case of the structure shown in FIG. 16 to FIG. 18, it is indispensable to finish the brazing build-up portion by grinding, but this work requires a great number of man-hours and
Since the work itself requires skill, it is difficult to secure workers domestically and internationally.

Therefore, both man-hours and required costs are large, and it is an operation that should be improved in the significant reduction of costs. Further, it is difficult to secure quality after brazing, which is a big problem for the body structure. Furthermore, even in the Mohican type shown in FIGS. 19 and 20, the brazing connection between the panel portions 110A and 110B is often performed, and such work requires a small number of man-hours and requires skill. There is an urgent need to improve work that does not.

The present invention was devised in view of the above problems, and is a welded joint structure of sheet metals and a welded joint of sheet metals, which enables thin sheet metals of automobiles and the like to be joined in good appearance, easily and at low cost. The purpose is to provide a method.

[0012]

Therefore, according to the welded joint structure of the sheet metal of the present invention described in claim 1, in the welded joint structure of the first sheet metal and the second sheet metal, the first sheet metal is joined. Part is formed with a hemming portion in which an end edge portion of the first sheet metal is folded back toward the second sheet metal side, and the hemming portion and the second sheet metal are polymerized to form the polymerized portion. Is characterized in that the folded back edge portion of the first sheet metal and the second sheet metal are weld-bonded to each other.

According to a second aspect of the present invention, there is provided a welded joint structure for sheet metal according to the present invention, wherein in the welded joint structure of the first sheet metal and the second sheet metal, the joint portion of the first sheet metal is the first sheet metal. Of the hemming-processed portion whose end edge portion is folded back toward the second sheet metal side, and the hemming-processed portion and the second sheet metal are polymerized to expose both exposed surfaces of the polymerized portion. It is characterized in that the overlapped portion is weld-bonded by resistance welding by electrode joining.

According to a third aspect of the present invention, there is provided a welded joint structure for sheet metal according to the second aspect, wherein the resistance welding is spot welding. According to a fourth aspect of the present invention, there is provided a welded joint structure for sheet metal according to the second or third aspect, wherein the resistance welding is performed by welding a joint between the folded portion of the hemming portion and the second sheet metal. Is mainly performed, and the welding conditions are set so that the welding of the joint portion of the first sheet metal itself in the hemmed portion is not promoted.

According to a fifth aspect of the present invention, there is provided a welded joint structure for sheet metal according to any one of the first to fourth aspects,
The first sheet metal and the second sheet metal are both formed as an automobile body panel, and the first sheet metal and the second sheet metal are joined together to form a substantially continuous surface. It is characterized by being configured.

According to a sixth aspect of the present invention, there is provided a welded joint structure for sheet metal according to the fifth aspect, wherein the first sheet metal is at the overlapping portion of the first sheet metal and the second sheet metal. It is characterized in that it is arranged on the body surface side with respect to the second sheet metal. According to a seventh aspect of the present invention, there is provided a welded joint structure for sheet metal according to the second or third aspect, in which the first sheet metal itself is joined to the joining surface in the hemmed portion.
The heat generation suppressing member having a melting point lower than that of the sheet metal is interposed.

According to an eighth aspect of the present invention, there is provided a welded joint structure for sheet metal according to the seventh aspect, characterized in that the heat generation suppressing member is a galvanized material. Further, the method of welding and joining sheet metals according to claim 9 is the method of welding and joining the first sheet metal and the second sheet metal, wherein an edge portion of the first sheet metal is used as a joint portion of the first sheet metal. A hemming step of folding back to the second sheet metal side for hemming, a polymerizing step of polymerizing the hemmed portion and the second sheet metal, and contacting electrodes on both exposed surfaces of the polymerized portion with resistance. And a welding step of welding and joining the overlapped portions by welding.

According to a tenth aspect of the present invention, there is provided a welding and joining method for sheet metal according to the ninth aspect, wherein spot welding is used for resistance welding in the welding step. According to an eleventh aspect of the present invention, in the method of welding and joining sheet metal according to the tenth aspect, in the welding step, the welding step includes bringing electrodes into contact with both exposed surfaces of the overlapped portion and energizing the electrodes for a required time. A contacting area of an electrode contacting the first sheet metal of the electrode is larger than an contact area of an electrode contacting the second sheet metal. I am trying.

According to a twelfth aspect of the present invention, in the method for welding and joining sheet metal according to the tenth aspect or the eleventh aspect, in the welding step, electrodes are brought into contact with both exposed surfaces of the overlapped portion. A first energizing step for energizing for a required time, a cooling step for cooling the overlapped portion by stopping energization to the electrode, and a second energizing step for energizing again for the required time after the cooling are provided. It is characterized by being.

According to a thirteenth aspect of the present invention, there is provided a method of welding and joining sheet metal according to any one of the ninth to twelfth aspects, in which the first sheet metal in the hemming portion is provided before the hemming step. A heat generation suppressing member interposing step for interposing a heat generation suppressing member having a melting point lower than that of the first sheet metal is provided on the bonding surface of itself.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. [First Embodiment] First, the first embodiment will be described. FIGS. 1 to 7 show a welded joint structure and a welded joint method of sheet metal as a first embodiment of the present invention. Is a partially cutaway perspective view showing an example of the shape of the welded joint, FIGS. 3 and 4 are schematic perspective views of an automobile body showing a portion where the structure can be adopted, and FIG. 5 shows a portion where the structure can be adopted. A schematic enlarged view of the automobile body shown (corresponding to the portion A in FIG. 4),
FIG. 6 is a schematic cross-sectional view of the main part of the structure, and FIG. 7 is a graph explaining the effect of the structure and method.

The structure of this embodiment is as shown in FIG.
This is a welded joint structure of the first sheet metal 10 and the second sheet metal 20, and the first sheet metal 10 and the second sheet metal 20 are joined at their respective edge portions. A hemming portion 30 is formed at the joint portion 11 of the first sheet metal 10 and the second sheet metal 20. That is, the joint portion 11 provided on the edge portion of the first sheet metal 10 is subjected to a process of folding back toward the second sheet metal 20 side, that is, a hemming process. Therefore, the joint portion 11 of the first sheet metal 10 is
The sheet metal 10 has a double structure including a main portion (joint portion upper layer) 12 and a folded portion (joint portion middle layer) 13 which is folded back for hemming.

On the other hand, the joint portion (joint lower layer) 21 of the second sheet metal 20 with the first sheet metal 10 is formed at the edge of the second sheet metal 20, and the joint portion 21 is a step 22. Through the second
Is formed so as to have a step with respect to the main part of the sheet metal 20. And the first having the hemmed portion 30
The joints 11 (12, 13) of the sheet metal 10 and the joint 21 of the second sheet metal 20 provided via the step 22 are polymerized as shown in FIGS. Spot welding is performed as resistance welding at the portion. In addition, the stepped portion 22 is formed so that the surface (upper surface) of the first sheet metal 10 and the surface (upper surface) of the second sheet metal 20 are flush with each other by this polymerization.
The level difference due to is set.

In the spot welding, the welding electrode 1 is brought into contact with the surface of the joining portion upper layer 12 of the first sheet metal 10 exposed upward in the overlapping portion of both sheet metals 10 and 20, and the second electrode exposed downward in the overlapping portion. The welding electrode 2 is brought into contact with the surface of the lower layer 21 of the joint portion of the sheet metal 20 and the electrodes 1 and 2 are energized. By the way, the overlapping portion to be welded is the hemmed portion 3 of the first sheet metal 10.
By 0, the three layers of the joint upper layer 12, the joint middle layer 13, and the joint lower layer 21 are in a superposed state, and by spot welding, the joint upper layer 12, the joint middle layer 13, and the joint lower layer 2 are formed.
Each joint with 1 may be welded. However, in the present structure, due to the operation principle described later, the welding between the joint middle layer 13 and the joint lower layer 21 becomes large and the nugget (welded mass) 3 is formed large, but the joint upper layer 12 and the joint portion Welding with the middle layer 13 is small, and the nugget (welding mass) 4 is not formed in this portion or is very small even if it is formed.

Such a welded joint structure of sheet metal is shown in FIG.
It can be used for joining automobile body panels as shown in FIG. That is, as shown in FIG. 3, the roof panel 101 of the automobile is designed to be polymerized and welded to the quarter panel 103 on the upper portion of the side body 102 from above. A welded joint structure as shown in can be applied.

Further, as shown in FIG. 4, the side roof rail 105 of the side body 102 of the automobile has a front portion 105.
A and the rear part 105B are divided, and these 105
Side roof rail 10 by connecting A and 105B
5, there is also a structure in which the side roof rail front portion 105A and the side roof rail rear portion 105B are particularly easy to be externally seen, but a welded joint structure as shown in FIG. 1 is also applied to this portion. can do.

Further, as a modified example of the welded joint structure of the sheet metal of this embodiment, a structure as shown in FIG. 2 can be constructed. Even with this structure, the joining portion 11 of the first sheet metal 10
The hemmed portion 30 is formed on the second sheet metal 20, and the joint portion 21 of the second sheet metal 20 is formed in a stepped shape with respect to the main portion of the second sheet metal 20 through the step portion 22.
Is a first step portion 22A having a deeper step than that of the first embodiment (see FIG. 1), and is formed on the edge side of the first step portion 22A and bent so as to rise to the first sheet metal 10 side. The second step portion 22B.

Therefore, the joint portion 21 of the second sheet metal 20 is
Has a concave surface portion 21A formed between the first step portion 22A and the second step portion 22B and a protruding surface portion 21B formed on the edge side of the second step portion 22B. Then, the projecting surface portion 21B is a joint portion welded by welding. Correspondingly, the folded-back portion (joint middle layer) 13 formed by the hemming portion 30 is also formed with a protruding portion 13A protruding so as to come into contact with the concave surface portion 21A of the joint portion 21 of the second sheet metal 20, The edge portion side of the folded-back portion 13 is bent so as to be joined to the joining portion upper layer 12, and forms a joining portion 13B.

Then, spot welding is performed by using both sheet metals 10 and 2.
No. 0, that is, the joint upper layer 12, the joint portion 13B of the joint middle layer 13, and the protruding surface portion 21B of the joint lower layer 21, and the welding electrode 1 is formed on the surface of the joint upper layer 12 of the first sheet metal 10. Are contacted with each other, the welding electrode 2 is contacted with the surface of the protruding surface portion 21B of the second sheet metal 20, and the electrodes 1 and 2 are energized.

In this structure, the step portion 2 in the second sheet metal is
2A is deeply formed, and also in the hemmed portion 30 of the first sheet metal 10, a bent portion 13 forming a step is formed. The sheet metal welded joint structure as shown in FIG. 2 can be used for joining automobile body panels as shown in FIGS. That is, as shown in FIG. 4 and FIG. 5, there is a structure in which a roof panel 101 of an automobile is polymerized and bonded to a side roof rail 105 on an upper portion of a side body 102 from above to form a Mohican type roof. The present welded joint structure as shown in FIG. 2 can be applied to the portion 106.

In each of the structures shown in FIGS. 1 and 2, after the nugget 3 is formed, the sealer 5 is filled in the portion where the first sheet metal 10 and the second sheet metal 20 are in contact with each other to form the first sheet metal 10. Liquid tightness between the sheet metal 10 and the second sheet metal 20 is ensured. The sheet metal welded joint structure as the first embodiment of the present invention is configured as described above, and the welded joint operation realized by the present welded joint structure will be described below as the first embodiment of the present invention. It will be explained together with the method.

That is, in the present welding and joining method, first,
A hemming process is performed on the joint portion 11 at the edge of the sheet metal 10 to form a stepped joint portion 21 at the edge portion of the second sheet metal 20 through the step portion 22. Then, as shown in FIG. 6, the welding electrode 1 is brought into contact with the surface of the first sheet metal 10 and the welding electrode 2 is brought into contact with the front surface (back surface of the body) of the welding position of the second sheet metal 20 to conduct electricity. To do.

As a result, the current flowing between the welding electrode 1 and the welding electrode 2 is linearly routed from the position of the welding electrode 1 on the first sheet metal 1 to the welding electrode 2 and the first
And a route b along the shape of the sheet metal 1. At this time, the current a flowing through the route a and the current b flowing through the route b
Quantitatively considering and, first, the current a is the first sheet metal 1
Since the joint upper layer 12 and the joint intermediate layer 0 of 0 are in the contact state of the bent sheet metal, they are not electrically completely connected. Therefore, the current a is equal to the junction upper layer 1
It becomes small due to the resistance between 2 and the junction middle layer 13.

On the other hand, the electric current b is circumvented along the bent shape of the first sheet metal 10, but since there is no cut portion and the electric resistance is small,
It becomes larger than the current a. In this way, if the current a flowing between the joint upper layer 12 and the joint middle layer 13 at the welding point is small, the temperature of the weld point (nugget forming portion) B between the joint upper layer 12 and the joint middle layer 13 rises. Becomes sluggish.

On the other hand, the current flowing between the joining middle layer 13 and the joining lower layer 21 at the welding point has a large value of the sum of the route a and the route b (= Ia + Ib). The temperature rise of the welding point (nugget forming portion) A with the joint lower layer 21 is caused by the joint upper layer 12 and the joint middle layer 1
It becomes faster than the welding point B with 3. For this reason, the relationship between the energization time of the welding electrodes 1 and 2 and the temperatures of the welding points A and B at this time is as shown in FIG.
When the energization is stopped after the energization for the time t, a time difference Δh1 until a nugget is formed as a welded portion occurs, and the nugget formation temperature at the welding point A becomes higher than the nugget formation temperature at the welding point B, as shown in FIG. So that welding point A
3 is formed to be significantly larger than the nugget 4 at the welding point B, and welding is performed mainly between the middle layer 13 of the joint portion of the first sheet metal 10 and the lower layer 21 of the joint portion of the second sheet metal 20. Becomes

In particular, when the energization is carried out for an appropriate time, it becomes possible to sufficiently form the nugget 3 at the welding point A while suppressing the formation of the nugget 4 at the welding point B. When the nugget formation with the middle layer 13 is suppressed and melted, thermal deformation due to welding of the surface of the joint upper layer 12, that is, the surface of the first sheet metal 10 in the overlapping portion is avoided,
It is possible to realize a welded joint that does not impair the appearance of the automobile.

As a result, it is possible to eliminate the work of surface finishing conventionally required for such a welded portion while surely joining the sheet metals together. That is, in the past, in order to improve the appearance of the welded joint, it was necessary to perform the brazing work for the welding and the finishing work of the brazing work, which requires a lot of skill in the welded joint. By eliminating the work of surface finishing,
There is an advantage that the man-hours and costs involved in the welding and joining of sheet metals can be significantly reduced, and the quality of the welded and joined products can be easily ensured.

Further, in the present welded joint structure, the first sheet metal 1
Although a gap 40 remains between 0 and the second sheet metal 20, by positively utilizing such a gap as a design of an automobile body, it is possible to reduce the man-hours and costs involved in the above-described welding connection. It is conceivable to develop new designs for the exterior appearance of automobile bodies while achieving reductions.

Next, the second embodiment will be described with reference to FIGS.
FIG. 10 shows a welded joint structure and a welded joint method of a sheet metal as a second embodiment of the present invention, FIG. 8 is a diagram for explaining the development purpose of the technique of this embodiment, and FIG. 9 is a main part of the structure. Fig. 10 is a schematic cross-sectional view, and Fig. 10 is a graph explaining the effect of the structure and method. This embodiment is a further development of the welded joint structure and method of the sheet metal of the first embodiment. That is, in the welded joint structure and method of the sheet metal,
The energization time is important, and if the energization time is not appropriate, the nugget 4 at the welding point B is formed large as shown in FIG. 8, and along with the formation of this nugget 4, the surface side of the first sheet metal 10 is formed. Distortion 6 occurs in the.

This embodiment is intended to avoid this. As shown in FIG. 9, the welding electrode 1A having a large contact area is brought into contact with the first sheet metal 10 side and the second sheet metal 20 side. The welding electrode 2 having a small contact area is brought into contact with the electric field to energize. With such a configuration, the current flowing between the welding electrode 1A and the welding electrode 2 is
It is divided into a current a that linearly goes from the position of the welding electrode 1A to the position of the welding electrode 2 at 0, and a current b that follows the shape of the first sheet metal 10.

At this time, when the current a flowing through the route a and the current b flowing through the route b are quantitatively considered, first, the current a is the upper layer 12 of the joining portion and the middle layer 1 of the joining portion of the first sheet metal 10.
Since 3 is a contact state of the bent sheet metal, these are not electrically completely connected. Therefore, the current a becomes small due to the resistance between the junction upper layer 12 and the junction intermediate layer 13.

On the other hand, the current b is in a state of circumventing along the bent shape of the first sheet metal 10, but since there is no cut portion and the electric resistance is small,
It becomes larger than the current a. Regarding the current a related to the nugget formation at the welding point B between the joining upper layer 12 and the joining middle layer 13, the current is diffused by the welding electrode 1A having a large contact area. Be lowered.

On the other hand, with respect to the current (a + b) related to the nugget formation at the welding point A between the middle layer 13 of the joint and the lower layer 21 of the joint, the current hardly diffuses due to the welding electrode 2 having a small contact area. Therefore, the current density at the welding point (nugget formation position) A is kept high. Due to such a relationship, the relationship between the energization time and the welding point temperature is as shown in FIG. That is, when electricity is applied for a predetermined time t, the time difference until a nugget as a welded part is formed is Δh1 compared to Δh1 in the first embodiment.
As shown in FIG. 9, the nugget 4 can be made smaller, and the nugget 3 can be formed to be significantly larger than the nugget 4, and the welding can be performed on the second sheet metal 20.
And the first sheet metal 10 (that is, between the joint middle layer 13 and the joint lower layer 21).

Therefore, in this embodiment, the nugget 4 is
Thus, the generation of the strain 5 accompanying the formation of the nugget 4 can be avoided. Next, a third embodiment will be described. FIG. 11 and FIG. 12 show a welded joint structure and a welded joint method of sheet metal as a third embodiment of the present invention, and FIG. 11 is a schematic view of a main part of the structure. FIG. 12 is a cross-sectional view, and FIG. 12 is a graph explaining the effect of the structure and method.

This embodiment is a further development of the sheet metal welded joint structure and method of the second embodiment. That is, in the third embodiment, as shown in FIG. 11, the welding electrode 1A having a large contact area is brought into contact with the surface of the first sheet metal 10 as in the second embodiment, and the welding electrode 2 is connected to the second electrode. Sheet metal 2
By contacting the back surface of the welding position of 0 and energizing,
The current density at the welding point (nugget forming position) B is reduced.

In this embodiment, the first sheet metal 1
The back surface of 0, that is, the surface on the side that is joined to each other by hemming the first sheet metal 10 is plated with a zinc-plated material 14 as a heat generation suppressing member having a lower melting point than that of the first sheet metal. There is. That is, as the first sheet metal 10, a single-sided alloy material 15 whose one surface is galvanized is used.

With such a configuration, the current flowing between the welding electrode 1A and the welding electrode 2 is a current a that linearly goes from the position of the welding electrode 1A to the position of the welding electrode 2 on the first sheet metal 10. When the current a flowing along the route a and the current b flowing through the route b are quantitatively considered by dividing the current a along the shape of the first sheet metal 10 into the current b, the current a is the first sheet metal 1
Since the bent joint sheet upper layer 12 and the joint portion middle layer 13 are in the contact state of the bent sheet metal, they are not in a completely electrically connected state, and the current a is equal to the joint portion upper layer 12 and the joint portion middle layer 13. It becomes smaller due to the resistance between and.

On the other hand, the electric current b is circumvented along the bent shape of the first sheet metal 10, but there is no cut portion and the electric resistance is small,
It becomes larger than the current a. Regarding the current a related to the nugget formation at the welding point B between the joining upper layer 12 and the joining middle layer 13, the current is diffused by the welding electrode 1A having a large contact area. Be lowered.

Further, due to the resistance of the galvanized material 14, the electric current a flowing through the welding point (nugget forming position) B between the joint upper layer 12 and the joint middle layer 13 becomes smaller. On the other hand, a current (a + b) related to the nugget formation at the welding point A between the middle layer 13 of the joint and the lower layer 21 of the joint.
With respect to the above, since the current does not diffuse much due to the welding electrode 2 having a small contact area, the current density at the welding point B is kept high.

Based on such a relationship, the relationship between the energization time and the welding point temperature is as shown in FIG. That is, when the energization is stopped at the predetermined time t, the time difference until the nugget as the welded portion is formed is Δ in the case of the second embodiment.
As shown in FIG. 11, the nugget 4 can be made smaller than the h2, and the nugget 3 is formed to be significantly larger than the nugget 4, and the welding is performed on the second sheet metal 20 and the first sheet metal 10. In other words, it is performed mainly between the middle layer 13 of the joint and the lower layer 21 of the joint.

Here, Δt related to the current a indicates a situation in which zinc of the galvanized material 14 is melted to reduce the contact resistance and suppress heat generation. During this time, the welding point of the portion where the nugget 4 is to be formed is shown. The rise in temperature is suppressed, which contributes to the action of increasing Δh3. In this way, at the time t when the nugget 4 should be formed, the temperature rise of the nugget 4 portion becomes equal to or lower than the predetermined value, so that the nugget 4 is not formed on the first sheet metal 10.

As a result, as shown in FIG. 10, the nugget 4 becomes smaller and is restricted to the galvanized 14 portion, the nugget 3 is formed to be significantly larger than the nugget 4, and the welding is second. Between the sheet metal and the edge portion 1A of the first sheet metal 1. Therefore, with this means, the nugget 8 is not formed, and some distortion 5 due to the formation of the nugget 8 is generated.
The occurrence of can be avoided.

Next, the fourth embodiment will be described with reference to FIG.
15 shows a welded joint structure and a welded joint method of a sheet metal as a fourth embodiment of the present invention, FIG. 13 is a schematic sectional view of a main part of the structure, and FIG. 14 is a diagram for explaining the method. FIG. 15 is a time chart, and is a graph for explaining the effect of the structure and method. This embodiment is a further development of the sheet metal welded joint structure and method of the third embodiment. That is, also in the fourth embodiment, as shown in FIG. 13, the welding electrode 1A having a large contact area is brought into contact with the surface of the first sheet metal 10 and the welding electrode 2 is connected to the second electrode as in the second embodiment. The current density at the welding point B is reduced by bringing the sheet metal 20 into contact with the back surface of the welding position and conducting electricity.

Further, also in this embodiment, the first sheet metal 1
The back surface of 0, that is, the surface on the side that is joined to each other by hemming the first sheet metal 10 is plated with a zinc-plated material 14 as a heat generation suppressing member having a lower melting point than that of the first sheet metal. There is. That is, as the first sheet metal 10, a single-sided alloy material 15 whose one surface is galvanized is used.

In the method of welding and joining sheet metals of this embodiment, welding is performed in the steps shown in FIG. That is, the electrodes 1A, 2 are pressed for a predetermined time (first energization time) Δt1 while pressurizing the two metal plates 10, 20.
The first energizing step of energizing the electrodes, and then the electrode 1
A cooling step in which the energization of A and 2 is stopped for a predetermined time (cooling time) Δt2 to cool the overlapping portion, and a second step of energizing the electrodes 1A and 2 again for the required time (second energization time) Δt3 after cooling This is performed by sequentially executing the energization step and. In addition, the pressurization of both the metal plates 10 and 20 starts with the initial pressurization before the first energization step, and the initial pressurization proceeds to the steady pressurization. During execution and during the required time after the end of the second energization step, this pressurized state is maintained.

With this structure, the relationship between the energization time and the welding point temperature is as shown in FIG. That is, the current b is cooled for a predetermined time Δt2 after the required time Δt1 for the same change as described above, and further, the welding point temperature rise due to energization for the time Δt3 is required for the time Δt.
It is performed with the same inclination as 1. On the other hand, with respect to the current a, as shown in FIG. 15, the relationship between the energization time and the welding point temperature is that, as shown in FIG. 15, after the required change time Δt1 similar to that described above, cooling is performed for a predetermined time Δt2, and further, the required time Δt3. The temperature rise of the welding point due to the energization is carried out with the same inclination as the required time Δt1.

At this time, the galvanized material 14 is cooled before being melted by cooling for a predetermined time Δt2, and the time difference Δh3 until the temperature reaches the nugget forming temperature as the welded portion is Δh.
4, the welding point B on the first sheet metal 10 side at the time t at which a predetermined amount of the nugget 3 to be de-energized is formed.
The temperature of is kept low enough. Therefore, nugget 4
At the time t at which the nugget 4 is to be formed, the temperature rise of the nugget 4 portion becomes equal to or less than the predetermined value, so that the nugget 4 in the first sheet metal 10 is not formed.

As a result, as shown in FIG. 13, the nugget 4 is not formed, only the nugget 3 is welded, and the strain 5 caused by the formation of the nugget 4 is avoided.

[0059]

As described in detail above, according to the welded joint structure of the sheet metal of the present invention described in claim 1, the first sheet metal and the second sheet metal are joined together.
In the welded joint structure with the sheet metal, the hemming portion is formed at the joint portion of the first sheet metal and the edge portion of the first sheet metal is folded back toward the second sheet metal side, and the hemming is performed. The processed portion and the second sheet metal are polymerized, and the folded edge portion of the first sheet metal in the polymerized portion and the second sheet metal are overlapped.
Since the structure is weld-bonded with the sheet metal of No. 2, it is possible to prevent welding hits and distortions from appearing on the outer surface even when welding thin sheet metals, so there is no need to perform brazing and grinding finish work as in the past. Thus, the work involved in welding can be greatly simplified, and good appearance quality can be easily obtained.

Further, as a result, the productivity is remarkably improved and the problem that a skilled worker must be secured can be solved. Further, the appearance quality is stabilized and the cost reduction effect is very large. Furthermore, since it is possible to avoid the generation of dust and noise that have been generated by the brazing and grinding work, there is an advantage that the worker can be freed from the finishing harmful work.

Further, even in a vehicle type or a factory where a large press cannot be used, the brazing and finishing work of the joint can be eliminated while ensuring the appearance, and the investment in the large press equipment can be avoided. In addition, the depth, width, shape, etc. of the connecting line can be freely designed by folding back and the outer plate parts can be directly welded, allowing a highly flexible design in terms of body structure. become.

According to the sheet metal welded joint structure of the present invention as defined in claim 2, in the welded joint structure of the first sheet metal and the second sheet metal, the joint portion of the first sheet metal is the first sheet metal. Of the sheet metal is formed by a hemming portion that is folded back toward the second sheet metal side, and the hemming portion and the second sheet metal are polymerized to form both exposed surfaces of the polymerized portion. With the structure in which the overlapped portion is welded and joined by resistance welding by electrode joining to the electrode, the same effect and advantage as the structure according to claim 1 can be more reliably obtained by resistance welding using hemming.

According to the welded joint structure of the sheet metal of the present invention described in claim 3, in the structure of claim 2, the resistance welding is spot welding, so that spot welding using hemming is performed. It is possible to more reliably obtain the same effects and advantages as the structure according to claim 1 or 2. According to the welded joint structure of the sheet metal of the present invention as set forth in claim 4, in the structure of claim 2 or 3, the resistance welding is performed by joining the folded portion of the hemming portion and the second sheet metal. The welding conditions are set so that the welding of the joining portion of the first sheet metal itself in the hemmed portion is not promoted, and thus welding striking and distortion do not appear on the outer surface. Therefore, it is possible to more reliably obtain the same effects and advantages as those of the structure according to claim 1 or 2.

According to the sheet metal welded joint structure of the present invention as set forth in claim 5, in the constitution as set forth in any one of claims 1 to 4, both the first sheet metal and the second sheet metal are automobiles. Of the first sheet metal and the second sheet metal are joined together to form a substantially continuous surface, thereby reducing manufacturing costs and manufacturing operations in automobile manufacturing. In addition to facilitating the above, there is an advantage that the degree of freedom in setting the connecting line is increased and the body can be freely designed.

According to the sheet metal welded joint structure of the present invention according to claim 6, in the structure according to claim 5, the above-mentioned first
With the configuration in which the first sheet metal is disposed on the body surface side of the second sheet metal in the overlapping portion of the sheet metal and the second sheet metal, the appearance of the welded portion in the automobile can be easily improved. This has the advantages of reducing manufacturing costs and facilitating manufacturing work in automobile manufacturing, increasing the degree of freedom in setting the connecting lines, and enabling free body design.

According to the welded joint structure of the sheet metal of the present invention described in claim 7, in the structure of claim 2 or 3, the first sheet metal is attached to the joint surface of the first sheet metal itself in the hemmed portion. With the configuration in which a heat generation suppressing member having a lower melting point is interposed, it becomes possible to minimize the occurrence of surface strain in the welded portion, and it is possible to more reliably obtain the above-mentioned effects and advantages. Become.

According to the welded joint structure of the sheet metal of the present invention described in claim 8, in the structure of claim 7, the heat generation suppressing member is a galvanized material. Suppression can be performed reliably, and the above-mentioned effects and advantages can be obtained more reliably. According to the method of welding and joining sheet metals according to claim 9,
In the method for welding and joining the sheet metal of the above and the second sheet metal,
A hemming step in which an edge portion of the first sheet metal is folded back toward the second sheet metal side as a joint portion of the sheet metal to perform a hemming process, and polymerization for polymerizing the hemmed portion and the second sheet metal By comprising a step and a welding step in which electrodes are brought into contact with both exposed surfaces of the overlapped portion to weld and join the overlapped portion by resistance welding, it is possible to prevent welding hitting and distortion from appearing on the outer surface. Since it is not necessary to perform brazing and its grinding and finishing work as in the conventional case, the work involved in welding can be greatly simplified, and good appearance quality can be easily obtained.

Further, as a result, the productivity is remarkably improved, and the problem that a skilled worker must be secured is solved. Further, the appearance quality is stabilized and the cost reduction effect is very large. Furthermore, since it is possible to avoid the generation of dust and noise that have been generated by the brazing and grinding work, there is an advantage that the worker can be freed from the finishing harmful work.

Further, even in a vehicle type or a factory that cannot work with a large-sized press, it is possible to eliminate the brazing and finishing work of the joint portion while ensuring the appearance, and to avoid the investment of a large-sized press facility. In addition, the depth, width, shape, etc. of the connecting line can be freely designed by folding back and the outer plate parts can be directly welded, allowing a highly flexible design in terms of body structure. become.

[0070] According to the sheet metal welding and joining method of the present invention as defined in claim 10, hemming is used because the resistance welding in the welding step uses spot welding in the structure according to claim 9. The spot welding described above can more reliably obtain the same effects and advantages as the method according to the ninth aspect. According to the method for welding and joining sheet metals of the present invention as set forth in claim 11, in the structure as set forth in claim 10, in the welding step, electrodes are brought into contact with both exposed surfaces of the overlapped portion, and the time required for the electrodes is reduced. By providing an energizing step for energizing, the contact area of the electrode of the electrode that contacts the first sheet metal is larger than the contact area of the electrode that contacts the second sheet metal. Further, there is an advantage that the occurrence of the surface strain of the welded portion can be more surely avoided, and the above-mentioned respective effects and advantages can be more surely obtained.

According to the twelfth aspect of the present invention, there is provided a method for welding and joining sheet metals, wherein in the structure of the tenth or eleventh aspect, the welding step includes contacting electrodes on both exposed surfaces of the overlapped portion. A first energizing step of energizing the electrodes for a required time, a cooling step of cooling the superposed section by stopping energization of the electrodes, and a second energizing step of energizing again for the required time after the cooling. With the configuration described above, there is an advantage that the occurrence of the surface distortion of the welded portion can be more surely avoided, and the above-described effects and advantages can be obtained more reliably.

According to the sheet metal welding and joining method of the present invention as set forth in claim 13, in the structure as set forth in any one of claims 9 to 12, before the hemming step, the first portion in the hemming portion is formed. With the configuration in which the heat generation suppressing member interposing step for interposing the heat generation suppressing member having a melting point lower than that of the first metal sheet is provided on the joining surface of the sheet metal itself, the occurrence of the surface strain of the welded portion can be more surely avoided. Thus, the effects and advantages described above can be obtained more reliably.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view showing an example of the shape of a welded joint portion of a welded joint structure for sheet metal as a first embodiment of the present invention.

FIG. 2 is a partially cutaway perspective view showing another example of the shape of the welded joint portion of the welded joint structure for sheet metal as the first embodiment of the present invention.

FIG. 3 is a schematic perspective view of an automobile body showing a portion where a welded joint structure of sheet metals as the first embodiment of the present invention can be adopted.

FIG. 4 is a schematic perspective view of an automobile body showing a portion that can adopt the welded joint structure of sheet metal according to the first embodiment of the present invention.

FIG. 5 is a schematic enlarged view (corresponding to part A in FIG. 4) of an automobile body showing a portion that can adopt the welded joint structure of sheet metal as the first embodiment of the present invention.

FIG. 6 is a schematic cross-sectional view of a main part of a welded joint structure for sheet metals as the first embodiment of the present invention.

FIG. 7 is a graph illustrating the effects of the sheet metal welded joint structure and method according to the first embodiment of the present invention.

FIG. 8 is a diagram illustrating a development purpose of a welded joint structure and method for sheet metal as a second embodiment of the present invention.

FIG. 9 is a schematic cross-sectional view of a main part of a welded joint structure for sheet metals as a second embodiment of the present invention.

FIG. 10 is a graph illustrating the effects of the sheet metal welded joint structure and method according to the second embodiment of the present invention.

FIG. 11 is a schematic cross-sectional view of a main part of a sheet metal welded joint structure according to a third embodiment of the present invention.

FIG. 12 is a graph illustrating the effects of the welded structure and method of sheet metal according to the third embodiment of the present invention.

FIG. 13 is a schematic cross-sectional view of a main part of a welded joint structure for sheet metals according to a fourth embodiment of the present invention.

FIG. 14 is a time chart illustrating a method of welded-bonding structure for sheet metal as a fourth embodiment of the present invention.

FIG. 15 is a graph illustrating an effect of the welded joint structure and method of sheet metal according to the fourth embodiment of the present invention.

FIG. 16 is a schematic exploded perspective view showing a state in which a conventional vehicle is connected to a body.

FIG. 17 is a cross-sectional perspective view taken along the line BB of FIG. 16 showing a state in which the body is connected to a conventional automobile.

FIG. 18 is a cross-sectional perspective view taken along the line BB in FIG. 16 showing a body coupling work state in a conventional automobile.

FIG. 19 is a schematic exploded perspective view showing another state of body connection in a conventional automobile.

FIG. 20 is a perspective view showing another state of body coupling in the conventional automobile, and the cross section in the drawing shows a cross section taken along the line CC of FIG.

FIG. 21 is a schematic cross-sectional view showing a state in which a conventional vehicle is connected to a body.

FIG. 22 is a schematic cross-sectional view showing a state in which a body is connected to a conventional automobile.

[Explanation of symbols]

1, 2 Welding electrodes 3, 4 Nugget (welded lump) 5 Sealer 6 Strain 10 First sheet metal 11 Joining part of first sheet metal 10 with second sheet metal 12 Joining upper layer 13 Folding part (joint middle layer) 13A Protruding part of folded part (joint part middle layer) 13B Joining part 14 Galvanized material 15 Single-sided alloy material 20 Second sheet metal 21 Joining part of second sheet metal 20 with first sheet metal 10 (joint lower layer) 21A Concave surface portion 21B Projection surface portion 22 Step portion 22A First step portion 22B Second step portion 30 Hemming processing portion 101 Roof panel 102 Side body 103 Quarter panel 104 Joining portion 105 Side roof rail 105A Side roof rail front portion 105B Side roof rail rear portion 106 Side roof rail Joining part A, B Welding point (nugget forming part)

Claims (13)

[Claims] 1. A welded joint structure of a first sheet metal and a second sheet metal, wherein an end edge portion of the first sheet metal is provided at a joint portion of the first sheet metal.
A hemmed portion that is folded back toward the sheet metal side is formed, the hemmed portion and the second sheet metal are polymerized, and the folded edge portion of the first sheet metal in the polymerized portion and the A welded joint structure of a sheet metal, characterized in that the second sheet metal and the second sheet metal are welded to each other. 2. In a welded joint structure of a first sheet metal and a second sheet metal, a joint portion of the first sheet metal has an edge portion of the first sheet metal and the second edge portion of the second sheet metal.
Of the hemming-processed part that is folded back toward the sheet metal side, and the hemming-processed part and the second sheet metal are polymerized, and the polymerization is performed by resistance welding by electrode bonding to both exposed surfaces of the polymerized part. Welded joint structure of sheet metal, characterized in that parts are welded together. 3. The welded joint structure for sheet metal according to claim 2, wherein the resistance welding is spot welding. 4. The resistance welding is mainly performed by welding a joint between the folded portion of the hemming portion and the second sheet metal, and a welding portion of the first sheet metal itself in the hemming portion is welded. The welded joint structure for sheet metal according to claim 2 or 3, wherein welding conditions are set so that welding is not promoted. 5. The first sheet metal and the second sheet metal,
Both are formed as a body panel of an automobile, and are configured such that the first sheet metal and the second sheet metal are joined together to form a substantially continuous surface. The welded joint structure of sheet metal according to any one of claims 1 to 4. 6. The overlapping portion of the first sheet metal and the second sheet metal, wherein the first sheet metal is arranged closer to the body surface side than the second sheet metal. The welded joint structure for sheet metal according to claim 5. 7. The heat generation suppressing member having a lower melting point than that of the first sheet metal is interposed on the joint surface of the first sheet metal itself in the hemming portion, and Welded joint structure of sheet metal described. 8. The welded joint structure for sheet metal according to claim 7, wherein the heat generation suppressing member is a galvanized material. 9. A method for welding and joining a first sheet metal and a second sheet metal, wherein an edge portion of the first sheet metal is folded back toward the second sheet metal side as a joint portion of the first sheet metal. A hemming step of applying a hemming step, a superposition step of superposing the hemmed portion and the second sheet metal, and an electrode is brought into contact with both exposed surfaces of the superposition section to weld the superposition section by resistance welding. A method of welding and joining sheet metals, which comprises a welding step. 10. The spot welding is used for the resistance welding in the welding step.
A method for welding and joining sheet metal as described. 11. The welding step includes an energizing step of abutting electrodes on both exposed surfaces of the overlapped portion to energize the electrodes for a required time, and abuts on the first sheet metal of the electrodes. The contact area of the electrode is configured to be larger than the contact area of the electrode contacting the second sheet metal.
A method for welding and joining sheet metal as described. 12. The welding step comprises a first energizing step in which electrodes are brought into contact with both exposed surfaces of the overlapped portion to energize the electrodes for a required time, and then the energization to the electrodes is stopped. The welded joint structure for sheet metal according to claim 10 or 11, further comprising a cooling step of cooling the overlapped portion and a second energization step of energizing again for a required time after the cooling. 13. Prior to the hemming step, a heat generation suppressing member interposing a heat generation suppressing member having a melting point lower than that of the first sheet metal on the joint surface of the first sheet metal itself in the hemming portion. The method for welding and joining sheet metals according to any one of claims 9 to 12, wherein steps are provided.