JP2021172138A - Vehicle body panel joining structure and vehicle body panel joining method - Google Patents

Abstract

To provide a vehicle body panel joining structure formed of aluminum alloy that has a stable joining strength, and a vehicle body panel joining method.SOLUTION: A vehicle body panel joining structure has a roof panel 10 formed of aluminum alloy, and a roof side rail 11 formed of aluminum alloy, the roof panel and the roof side rail being welded using a filler material of aluminum alloy. The tensile strength of the filler material is set to be higher than the tensile strength of the member that has a lower tensile strength in the base material of the roof panel 10 and the base material of the roof side rail 11. A throat thickness (a) of a welding metal portion 20 including the filler material and leg lengths (b) and (c) thereof are equal to or greater than the plate thickness of the base material that has a thin plate thickness in the base material of the roof panel 10 and the base material of the roof side rail 11.SELECTED DRAWING: Figure 3

Description

The present invention relates to a vehicle body panel joining structure and a vehicle body panel joining method.

Conventionally, welding using an aluminum alloy filler material may be applied to the joint between the roof panel of the vehicle body and the side outer panel of the roof side rail. However, in general, in the case of welding using a filler metal of an aluminum alloy, it is difficult to secure sufficient joint strength. The following Patent Document 1 describes a first plate material which is a steel plate on which a first joint portion is formed, a second plate material which is an aluminum plate on which a second joint portion to be joined to the first joint portion is formed, and a first plate material. A brazing material that is an aluminum brazing material that is interposed between the joint portion and the second joint portion and joins the first joint portion and the second joint portion, and a brazing material and a dissimilar metal among the first joint portion and the second joint portion. A vehicle panel provided with a surface enlargement portion having at least one of a convex shape and a concave shape formed in a range in contact with the brazing material on the side, and the surface enlargement portion has irregularities formed by a stepped shelf portion. The joint structure is disclosed. Then, it is said that the bonding strength between the first plate material and the second plate material can be secured by expanding the bonding area with the brazing material.

Japanese Patent No. 6048458

By the way, in recent years, in order to further reduce the weight of the vehicle body, it is required that both the roof panel and the outer panel of the roof side rail are made of aluminum alloy. Therefore, it is desired to develop a bonding structure capable of welding aluminum alloy panels to each other with a high bonding strength using an aluminum alloy filler material. A 6000 series aluminum alloy is generally used as a panel material for automobiles. Since the 6000 series aluminum alloy has poor high temperature crack resistance during welding and cracks are likely to occur during welding, it is common to use a filler metal of the 4000 series aluminum alloy having excellent high temperature crack resistance in welding. However, the weld metal part formed by using the filler metal of the 4000 series aluminum alloy has a smaller breaking elongation than the 6000 series aluminum alloy base material, and needs to be broken preferentially due to the local strain concentration due to the joint shape. It is difficult to obtain a good joint strength.

Therefore, the present invention provides a joining structure of an aluminum alloy car body panel having a stable joining strength, and a method of joining the car body panel.

In the joint structure of the vehicle body panel of the present invention, a roof panel made of an aluminum alloy (for example, the roof panel 10 in the embodiment) and a roof side rail made of an aluminum alloy (for example, the roof side rail 11 in the embodiment) are made of an aluminum alloy. In the joint structure of the vehicle body panel welded using the filler metal, the tensile strength of the filler metal is higher than the tensile strength of the roof panel member and the base material of the roof side rail, which have a lower tensile strength. The throat thickness (for example, the throat thickness a in the embodiment) and the leg length (for example, the leg lengths b and c in the embodiment) of the weld metal portion (for example, the weld metal portion 20 in the embodiment) including the filler metal are set. The base material of the roof panel and the base material of the roof side rail are characterized in that the plate thickness is equal to or greater than the plate thickness of the base material having a thin plate thickness.
In the method of joining the vehicle body panel of the present invention, an aluminum alloy roof panel (for example, the roof panel 10 in the embodiment) and an aluminum alloy roof side rail (for example, the roof side rail 11 in the embodiment) are joined to an aluminum alloy. In the method of joining the body panel to be welded using the filler metal, the tensile strength of the filler metal is higher than the tensile strength of the roof panel member and the base material of the roof side rail, which have a lower tensile strength. The throat thickness (for example, the throat thickness a in the embodiment) and the leg length (for example, the leg lengths b and c in the embodiment) of the weld metal portion (for example, the weld metal portion 20 in the embodiment) including the filler metal are set. The base material of the roof panel and the base material of the roof side rail are characterized in that the plate thickness is equal to or greater than the plate thickness of the base material having a thin plate thickness.

According to the present invention, since the breaking elongation of the weld metal portion is smaller than that of the roof panel and the roof side rail by increasing the tensile strength, a tensile load acts due to a side collision such as a pole collision to act on the weld metal portion. Local strain concentration occurs on. As a result, the weld metal portion breaks with priority over the base metal. That is, the joint strength of the roof panel and the roof side rail depends on the tensile strength of the weld metal portion. The tensile strength of this filler metal is set higher than the tensile strength of the members with low tensile strength among the base metal of the roof panel and the base metal of the roof side rail, and the throat thickness and leg length of the weld metal part including the filler metal are set. , Of the base material of the roof panel and the base material of the roof side rail, the thickness of the base material is thicker than that of the base material, which stabilizes the joint strength of the roof panel and the roof side rail and breaks due to a side collision such as a pole collision. It can be difficult to do.

In the joint structure of the vehicle body panel, the dilution ratio of the weld metal portion may be 35% or less.
In the above-mentioned method for joining body panels, the dilution ratio of the weld metal portion may be 35% or less.

The tensile strength of the weld metal portion depends on the mixing ratio of the base metal and the filler metal, that is, the dilution ratio. Therefore, by optimizing this dilution ratio, the joint strength of the roof panel and the roof side rail can be stabilized. According to the present invention, it is possible to obtain a joint strength that does not break even when a tensile load is applied to the joint portion between the roof panel and the roof side rail due to a pole collision. This is particularly remarkable when the filler metal is a 4000 series aluminum alloy and the base material is a 6000 series aluminum alloy.

In the joint structure of the vehicle body panel, the penetration rate of the molten portion may be 45% or less.
In the above-mentioned method of joining the vehicle body panel, the penetration rate of the molten portion may be 45% or less.

According to the present invention, since the state in which the dilution ratio of the weld metal portion is 35% or less can be controlled, the joint strength that does not break even if a tensile load is applied to the joint portion between the roof panel and the roof side rail due to a pole collision can be obtained. You can definitely get it.

According to the present invention, it is possible to provide a joining structure of a vehicle body panel made of an aluminum alloy having stable bonding strength and a joining method of the vehicle body panel.

It is a perspective view of the vehicle which adopted the joint structure of the body panel of an embodiment. FIG. 2 is a cross-sectional view taken along the line II-II of FIG. It is an enlarged view of the main part of FIG. It is a graph which shows the relationship of the tensile strength of the joint part of a roof panel and a side outer panel with respect to the dilution ratio of a weld metal part. It is a graph which shows the relationship of the tensile strength of the joint part of a roof panel and a side outer panel with respect to the penetration rate of a weld metal part.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The directions such as front-rear, up-down, left-right, etc. in the following description are the same as the directions in the vehicle described below. That is, the vertical direction coincides with the vertical direction, and the horizontal direction coincides with the vehicle width direction. Further, in the drawings used in the following description, the arrow UP indicates the upper side, the arrow FR indicates the front side, and the arrow LH indicates the left side.

FIG. 1 is a perspective view of a vehicle adopting the joint structure of the vehicle body panel of the embodiment.
As shown in FIG. 1, the vehicle 1 adopting the joining structure and joining method of the vehicle body panels of the embodiment is attached to the roof panel 10 arranged on the roof portion and both edges of the roof panel 10 on the outer side in the vehicle width direction. The roof side rail 11 is provided, and the front pillar 12 connected to the front end portion of the roof side rail 11 is provided. The left and right roof side rails 11 have a structure in which the closed cross sections are continuous in the front-rear direction. The front pillar 12 has a closed cross section continuous with the roof side rail 11. The front pillar 12 extends from the front end portion of the roof side rail 11 toward the front lower side. The windshield glass 13 is arranged in the front end portion of the roof panel 10 and the area surrounded by the left and right front pillars 12.

FIG. 2 is a cross-sectional view taken along the line II-II of FIG.
As shown in FIG. 2, the roof panel 10 uses a plate material made of an aluminum alloy as a base material. The left and right side ends of the roof panel 10 are bent downward. Specifically, the roof panel 10 has a top plate portion 10a extending in the vehicle width direction and a bent portion 10b extending downward from the left and right edge edges of the top plate portion 10a in a cross-sectional view orthogonal to the front-rear direction. And a side plate portion 10c extending downward from the lower end edge of the bent portion 10b and inward in the vehicle width direction.

The roof side rail 11 is formed by joining a side outer panel 14 that forms the exterior design surface of the vehicle and a side inner panel (not shown) arranged on the vehicle interior side of the side outer panel 14. The roof side rail 11 forms a closed cross section along the front-rear direction by the side outer panel 14 and the side inner panel. The side outer panel 14 uses a plate material made of an aluminum alloy as a base material. The plate thickness of the base material of the side outer panel 14 is equal to the plate thickness of the base material of the roof panel 10. The plate thickness of the base metal is equal to the plate thickness of the flat portion of the molded panel that is not bent. The side outer panel 14 includes a vertical wall 14a extending in a direction intersecting the vehicle width direction and an upper wall 14b extending outward from the upper end edge of the vertical wall 14a in the vehicle width direction in a cross-sectional view orthogonal to the front-rear direction. The side plate portion 10c of the roof panel 10 is arranged along the vertical wall 14a, and the bent portion 10b of the roof panel 10 faces the vertical wall 14a.

The roof panel 10 and the side outer panel 14 are joined to each other by welding using a filler metal of an aluminum alloy. The tensile strength of the filler metal is set higher than the tensile strength of the base material having the lower tensile strength among the base material of the roof panel 10 and the base material of the side outer panel 14. Laser welding is applied as the welding method. Welding is continuously performed along the front-rear direction with respect to the bent portion 10b of the roof panel 10 and the vertical wall 14a of the side outer panel 14. A weld metal portion 20 formed by welding is arranged between the bent portion 10b of the roof panel 10 and the vertical wall 14a of the side outer panel 14. The weld metal portion 20 is a portion containing the filler metal. The weld metal portion 20 is formed so as to be continuous with the roof panel 10 and the side outer panel 14, unlike mechanical joining such as fastening.

The weld metal portion 20 will be described in detail.
FIG. 3 is an enlarged view of a main part of FIG.
As shown in FIG. 3, the throat thickness a and the leg lengths b and c of the weld metal portion 20 are defined as follows. The throat thickness a is the thickness of the thinnest portion of the cross section of the weld metal portion 20 including the base metal in the normal direction of the reference point with the surface 20a of the weld metal portion 20 as a reference point. The leg lengths b and c are distances between the intersections of the weld metal portion 20 and the surfaces of the members to be welded (each of the roof panel 10 and the side outer panel 14) in the cross section of the weld metal portion 20. In the present embodiment, each of the throat thickness a and the leg lengths b and c of the weld metal portion 20 is equal to or larger than the plate thickness of the base material of the roof panel 10 and the side outer panel 14. The surface 20a of the weld metal portion 20 is formed in a concave shape in the cross section of the weld metal portion 20.

Here, the dilution ratio of the weld metal portion 20 is 35% or less. Further, the penetration rate of the weld metal portion 20 is 45% or less. The dilution ratio of the weld metal portion 20 is defined as the ratio of the area of the portion where the member to be welded (base material) is dissolved in the filler metal to the total area of the weld metal portion 20 in the cross section of the weld metal portion 20. NS. Further, the penetration rate of the weld metal portion 20 is defined by the ratio of the depths d and e in which the filler metal has melted into the welded member with respect to the thickness of the base material of the welded member in the cross section of the welded metal portion 20. Will be done. In FIG. 3, the depths d and e that have blended in are drawn deeper than they actually are in order to make it easier to understand. Further, by setting the curvature formed by the surface of the side outer panel 14 and the surface 20a of the weld metal portion 20 to 3.0 or more and the intersection angle to 145 ° or more, the curvature becomes gentle and the stress due to the tensile load of the pole collision becomes large. Concentration can be suppressed, and breakage of the joint portion between the roof panel 10 and the side outer panel 14 can be suppressed.

Next, the joining structure of the vehicle body panel and the operation of the joining method of the present embodiment will be described.
FIG. 4 is a graph showing the relationship between the tensile strength of the joint portion between the roof panel and the side outer panel with respect to the dilution ratio of the weld metal portion. In FIG. 4, the plurality of plot data are the measured values of the dilution ratio and the tensile strength of each of the plurality of samples whose tensile strength was measured.
As shown in FIG. 4, the tensile strength of the joint portion between the roof panel 10 and the side outer panel 14 has a linear relationship with the dilution rate. Specifically, the relationship between the dilution rate and the tensile strength is shown by the approximate straight line A in the figure. Here, the straight line B in the figure is a straight line showing the relationship between the dilution rate and the value obtained by subtracting 3σ (σ is the standard deviation) of the tensile strength from the tensile strength. In this way, by setting the dilution ratio of the weld metal portion 20 to 35% or less in consideration of the variation in tensile strength, it is possible to secure the tensile strength equal to or higher than the standard at the joint portion between the roof panel 10 and the side outer panel 14.

FIG. 5 is a graph showing the relationship between the tensile strength of the joint portion between the roof panel and the side outer panel with respect to the penetration rate of the weld metal portion. In FIG. 5, the plurality of plot data are measured values of the penetration rate and the tensile strength of each of the plurality of samples whose tensile strength was measured.
As shown in FIG. 5, the tensile strength of the joint portion between the roof panel 10 and the side outer panel 14 can secure a tensile strength equal to or higher than the standard when the penetration rate of the weld metal portion 20 is 45% or less.

In the above-mentioned measurement of tensile strength, the roof panel 10 and the side outer panel 14 are press-molded with a plate material having a thickness of 1.0 mm made of an aluminum 6000 series alloy, and the wire diameter made of an aluminum 4000 series alloy is used as a filler material. After joining the roof panel 10 and the side outer panel 14 with a 6 mm filler, a sample that had undergone a heating step of a coating / drying furnace was used.

As described above, in the present embodiment, the tensile strength of the filler metal is set higher than the tensile strength of the member having the lower tensile strength among the roof panel 10 and the side outer panel 14 (these are the base materials), and the filler metal is set. The throat thickness a and the leg lengths b and c of the weld metal portion 20 including the above are equal to or larger than the thickness of the base material having a thin plate thickness among the base material of the roof panel 10 and the base material of the side outer panel 14. According to this configuration, since the weld metal portion 20 has a smaller breaking elongation than the roof panel 10 and the side outer panel 14, it breaks preferentially over the base metal due to local strain concentration on the weld metal portion 20. As a result, the joint strength of the roof panel 10 and the side outer panel 14 depends on the tensile strength of the weld metal portion 20. The tensile strength of the weld metal portion 20 depends on the mixing ratio of the base metal and the filler metal, that is, the dilution ratio. Therefore, by optimizing the dilution ratio, the joint strength of the roof panel 10 and the side outer panel 14 can be stabilized.

The dilution ratio of the weld metal portion 20 is 35% or less. According to this configuration, it is possible to obtain a joint strength that does not break even if a tensile load is applied to the joint portion between the roof panel 10 and the side outer panel 14 due to a pole collision.

Further, the penetration rate of the weld metal portion 20 is 45% or less. According to this configuration, it is possible to control the state in which the dilution ratio of the weld metal portion 20 is 35% or less, so that the joint portion between the roof panel 10 and the side outer panel 14 is not broken even if a tensile load is applied due to a pole collision. The strength can be surely obtained.

The present invention is not limited to the above-described embodiment described with reference to the drawings, and various modifications can be considered within the technical scope thereof.
For example, in the above embodiment, the plate thickness of the base material of the side outer panel 14 is equal to the plate thickness of the base material of the roof panel 10, but the plate thicknesses of the base materials may be different from each other.

Further, the present invention can be applied when at least a part of the roof side rail is made of an aluminum alloy. That is, when the roof side rail is formed of a steel panel and an aluminum alloy panel, the aluminum alloy panel of the roof side rail is used for the aluminum alloy roof panel, and the aluminum alloy filler material is used. The present invention can be applied to the case of welding.

In addition, it is possible to replace the components in the above-described embodiment with well-known components as appropriate without departing from the spirit of the present invention.

10 ... Roof panel 11 ... Roof side rail 20 ... Welded metal part a ... Throat thickness b, c ... Leg length

Claims (6)

In the joint structure of the vehicle body panel in which the roof panel made of aluminum alloy and the roof side rail made of aluminum alloy are welded using a filler material of aluminum alloy.
The tensile strength of the filler metal is set higher than the tensile strength of the member having a low tensile strength among the base material of the roof panel and the base material of the roof side rail.
The throat thickness and leg length of the weld metal portion including the filler metal are equal to or larger than the thickness of the base material of the roof panel and the base material of the roof side rail, which are thinner than the base material.
The joint structure of the car body panel is characterized by this. The dilution ratio of the weld metal portion is 35% or less.
The joint structure of a vehicle body panel according to claim 1. The penetration rate of the weld metal portion is 45% or less.
The joint structure of a vehicle body panel according to claim 1. In a method of joining a vehicle body panel in which an aluminum alloy roof panel and an aluminum alloy roof side rail are welded using an aluminum alloy filler material,
The tensile strength of the filler metal is set higher than the tensile strength of the member having a low tensile strength among the base material of the roof panel and the base material of the roof side rail.
The throat thickness and leg length of the weld metal portion including the filler metal are equal to or larger than the thickness of the base material of the roof panel and the base material of the roof side rail, which are thinner than the base material.
A method of joining body panels, which is characterized by this. The dilution ratio of the weld metal portion is 35% or less.
The method for joining a vehicle body panel according to claim 4, wherein the method is characterized by the above. The penetration rate of the weld metal portion is 45% or less.
The method for joining a vehicle body panel according to claim 4, wherein the method is characterized by the above.

Images