JP2022141085A - Lap-welded joint structure and suspension member - Google Patents

Abstract

To provide a lap-welded joint structure and a suspension member which may suppress or prevent the generation of a gas defect such as a wormhole causing the mechanical characteristic reduction.SOLUTION: The lap-welded joint structure is a lap-welded joint structure including a fillet welding part which joins aluminum alloy base materials. The lap-welded joint structure includes one or more protrusions which are arranged on a mating surface of one aluminum alloy base material, projecting toward and contact a mating surface of the other aluminum alloy base material, and are continuous or discontinuous along an extension direction of the fillet welding part. The lap-welded joint structure has a gap that is formed of the one aluminum alloy base material, the other aluminum alloy base material and the fillet welding part and communicates in the extension direction of the fillet welding part.SELECTED DRAWING: Figure 2

Description

TECHNICAL FIELD The present invention relates to a lap weld joint structure and a suspension member, and more particularly to a lap weld joint structure between aluminum alloy base metals and an automobile suspension member to which this lap weld joint structure is applied.

Conventionally, when making a welded joint using an aluminum plate as a base material, while allowing a certain amount of variation in the gap dimension between the mating surfaces that are to be the welds, the occurrence of blowholes is suppressed and the weld strength is improved. A joint structure that enables stabilization has been proposed (see Patent Document 1). This joint structure is a lap joint structure in which a portion of the aluminum-based base material is overlapped and then fillet-welded by the MIG welding method. In this lap joint structure, recessed grooves opening toward a region to be a fillet are intermittently formed in advance along the welding direction on either one of the mating surfaces that are to be overlaid on each other.

JP-A-2003-136243

However, in the mating surfaces of the aluminum-based base material of the lap joint structure as described in Patent Document 1, there is a portion where the concave groove is not formed along the welding direction. Therefore, the gas in the molten metal at that portion cannot be released sufficiently, and in the lap joint structure as described in Patent Document 1, gas defects such as wormholes that cause deterioration of mechanical properties occur. There was a problem that

The present invention has been made in view of such problems of the prior art, and its object is to suppress or prevent the occurrence of gas defects such as wormholes that cause deterioration of mechanical properties. It is an object of the present invention to provide a lap joint structure and a suspension member that can be used.

As a result of extensive studies to achieve the above object, the present inventors have found that one aluminum alloy base material having a predetermined convex portion and a fillet weld for joining the aluminum alloy base materials to each other and the other aluminum We have found that the above object can be achieved by forming a lap weld joint structure formed of an alloy base material and a fillet weld and having a gap communicating in the extending direction of the fillet weld, and have completed the present invention. Arrived.

That is, the lap weld joint structure of the present invention is a lap weld joint structure having fillet welds for joining aluminum alloy base metals. This lap weld joint structure abuts against the mating surface of one aluminum alloy base metal so as to protrude toward the mating surface of the other aluminum alloy base metal, and is continuous or intermittent along the extending direction of the fillet weld. It has a convex portion. This lap weld joint structure is formed of one aluminum alloy base material, the other aluminum alloy base material, and a fillet weld, and has a gap communicating in the extending direction of the fillet weld.

Further, the suspension member of the present invention is a suspension member having a cylindrical portion formed of one aluminum alloy base material having a concave cross-sectional shape and the other aluminum alloy base material. At least a portion of this cylindrical portion has a closed cross-sectional structure formed by the lap welded joint structure of the present invention.

According to the present invention, a fillet weld for joining aluminum alloy base materials is provided, and is formed of one aluminum alloy base material having a predetermined convex portion and the other aluminum alloy base material and the fillet weld, A lap weld joint structure and a suspension that can suppress or prevent the occurrence of gas defects such as wormholes that cause deterioration of mechanical properties because the lap weld joint structure has a gap that communicates in the extending direction of the fillet weld. can provide members.

FIG. 1 is a perspective view showing a suspension member according to Embodiment 1-1 of the present invention. 2 is a perspective view of a portion surrounded by line II in the suspension member shown in FIG. 1. FIG. FIG. 3 is a perspective view of the lap weld joint structure according to the 2-2 embodiment in the suspension member according to the 2-1 embodiment of the present invention. FIG. 4 is a perspective view of the lap weld joint structure according to the 3-2 embodiment in the suspension member according to the 3-1 embodiment of the present invention. FIG. 5 is a perspective view of a lap weld joint structure according to a 4-2 embodiment in a suspension member according to a 4-1 embodiment of the present invention. FIG. 6 is a perspective view of the lap weld joint structure according to the 5-2 embodiment in the suspension member according to the 5-1 embodiment of the present invention.

Hereinafter, suspension members and lap weld joint structures according to some embodiments of the present invention will be described in detail with reference to the drawings. Note that the dimensional ratios in the drawings quoted below are exaggerated for convenience of explanation, and may differ from the actual ratios.

(First embodiment)
FIG. 1 is a perspective view showing a suspension member according to Embodiment 1-1. As shown in FIG. 1, the suspension member 100 of the 1-1 embodiment includes one aluminum alloy base material 10 having a concave cross-sectional shape (hereinafter sometimes referred to as "first aluminum alloy base material 10") and , and the other aluminum alloy base material 20 (hereinafter sometimes referred to as “second aluminum alloy base material 20”). At least part of the tubular portion 110 has a closed cross-sectional structure 111 formed of a predetermined lap weld joint structure 1, which will be described later. As the first or second aluminum alloy base material 10, 20, it is preferable to appropriately use, for example, an aluminum alloy that can be applied to structural members of automobiles. Reference numeral 30 in FIG. 1 indicates a fillet weld. The fillet welded portion 30 is preferably formed by arc welding, for example, and is preferably formed by MIG welding. In the illustrated example, the other aluminum alloy base material 20 also has a concave cross-sectional shape, but the structure of the suspension member in the present invention is not limited to this, and the other aluminum alloy base material may have a flat plate shape. . Also, in the illustrated example, the suspension member 100 has a grid structure, but the structure of the suspension member in the present invention is not limited to this.

A given lap weld joint structure 1 will now be described in detail. 2 is a perspective view of a portion surrounded by line II in the suspension member shown in FIG. 1. FIG. As shown in FIG. 2, the lap weld joint structure 1 of the 1-2 embodiment in the suspension member 100 of the 1-1 embodiment is formed between aluminum alloy base materials, that is, the first aluminum alloy base material 10 and the second 2 aluminum alloy base material 20 and a fillet weld 30 joining them.

The lap welded joint structure 1 of the present embodiment has a mating surface 10A of the first aluminum alloy base material 10 (hereinafter sometimes referred to as “first mating surface 10A”) at one end of which the second aluminum alloy base material 20 is mated. A convex portion 11 (hereinafter referred to as “first convex portion 11 ).

The lap weld joint structure 1 of the present embodiment is formed by being surrounded by a first aluminum alloy base material 10, a second aluminum alloy base material 20, and a fillet weld 30. In the extending direction of the fillet weld 30, It has a communicating gap 1A.

The lap weld joint structure of the present embodiment includes a fillet weld that joins aluminum alloy base materials together, one aluminum alloy base material having a predetermined protrusion, and the other aluminum alloy base material and the fillet weld. and has a gap communicating in the extending direction of the fillet weld. Therefore, in the lap welded joint structure of the present embodiment, gas such as hydrogen gas generated from the molten metal during welding is introduced through two locations, one end and the other end, of the gap communicating in the extending direction of the fillet weld. It can escape to the outside and reduce the amount of gas in the molten metal. As a result, in the lap welded joint structure of the present embodiment, it is possible to suppress or prevent the occurrence of gas defects such as wormholes that cause deterioration of mechanical properties.

In the lap weld joint structure of the present embodiment, the distance between the first mating surface 10A of the first aluminum alloy base material 10 and the second mating surface 20A of the second aluminum alloy base material 20 is 0.3 mm or more and 2.5 mm. The following are preferable. By setting the height of the continuous first protrusion to 0.3 mm or more, the distance between the first mating surface 10A and the second mating surface 20A becomes 0.3 mm or more, which is the same as the height of the first protrusion. The gas generated from the molten metal can be sufficiently released to the outside through one end and the other end of the gap, and the occurrence of gas defects such as wormholes that cause deterioration of mechanical properties can be further suppressed or prevented. Furthermore, by setting the height of the continuous first projections to 2.5 mm or less, the distance between the first mating surface 10A and the second mating surface 20A becomes 2.5 mm or less, which is the same as the height of the first projections. Therefore, it is possible to suppress or prevent deterioration of welding quality due to molten metal flowing into the gap.

In the lap welded joint structure of the present embodiment, the first aluminum alloy base material is preferably an aluminum alloy casting. By using an aluminum alloy casting as the first aluminum alloy base material, the first protrusions can be easily provided on the first mating surfaces without increasing the number of steps when forming the first aluminum alloy base material by casting. For the same reason, in the present invention, the second aluminum alloy base material may be an aluminum alloy casting.

The suspension member of the present embodiment includes a tubular portion formed of one aluminum alloy base material having a concave cross-sectional shape and the other aluminum alloy base material, and at least a portion of the tubular portion is the overlapping member of the present embodiment. It has a closed cross-sectional structure formed by a welded joint structure. Therefore, in the suspension member of the present embodiment, the rigidity of the cylindrical portion having a closed cross-section structure by line welding formed by fillet welding of the lap weld joint structure is replaced by a closed cross-section structure by point fastening formed by bolts. It can be made higher than the rigidity of the cylindrical portion. As a result, in the suspension member of the present embodiment, it is not necessary to form ribs or the like for ensuring rigidity, and the base material can be made thinner with the same rigidity, and the weight of the automobile to which this is applied can be reduced. can be done.

(Second embodiment)
FIG. 3 is a perspective view of the lap weld joint structure according to the 2-2 embodiment in the suspension member according to the 2-1 embodiment of the present invention. Specifically, it is a perspective view of a portion of the suspension member according to the 2-1 embodiment, which is surrounded at the same position as line II shown in FIG. Note that the same reference numerals as those described in the first embodiment are assigned to the same components, and the description thereof is omitted.

As shown in FIG. 3, the lap welded joint structure 2 of this embodiment includes a first aluminum alloy base material 10, a second aluminum alloy base material 20, and a fillet weld 30 joining them.

The lap weld joint structure 2 of the present embodiment protrudes toward the second mating surface 20A of the second aluminum alloy base material 20 and abuts on the middle of the first mating surface 10A of the first aluminum alloy base material 10. It has a continuous first convex portion 11 along the extending direction of the meat welded portion 30 .

The lap weld joint structure 2 of the present embodiment is formed by being surrounded by a first aluminum alloy base material 10, a second aluminum alloy base material 20, and a fillet weld 30, and in the extending direction of the fillet weld 30 It has a communicating gap 2A.

The lap weld joint structure of the present embodiment includes a fillet weld that joins aluminum alloy base materials together, one aluminum alloy base material having a predetermined protrusion, and the other aluminum alloy base material and the fillet weld. and has a gap communicating in the extending direction of the fillet weld. Therefore, in the lap welded joint structure of the present embodiment, gas such as hydrogen gas generated from the molten metal during welding is introduced through two locations, one end and the other end, of the gap communicating in the extending direction of the fillet weld. It can escape to the outside and reduce the amount of gas in the molten metal. As a result, in the lap welded joint structure of the present embodiment, it is possible to suppress or prevent the occurrence of gas defects such as wormholes that cause deterioration of mechanical properties.

In the lap welded joint structure of the present embodiment, since the first protrusion 11 is provided in the middle of the first mating surface 10A, the first protrusion 11 is provided at one end of the first mating surface 10A. Compared to the lap welded joint structure of the first embodiment, it is less likely to deform due to heat input during welding. Therefore, the lap welded joint structure of the present embodiment is applied when the first convex portion and the fillet welded portion are separated from each other due to the heat input during welding, and the gap dimension greatly changes due to the deformation of the base material. is preferred.

Also in the lap weld joint structure of the present embodiment, the preferred form and material types of the lap weld joint structure of the first embodiment can be appropriately adopted.

The suspension member of the present embodiment includes a tubular portion formed of one aluminum alloy base material having a concave cross-sectional shape and the other aluminum alloy base material, and at least a portion of the tubular portion is the overlapping member of the present embodiment. It has a closed cross-sectional structure formed by a welded joint structure. Therefore, in the suspension member of the present embodiment, the rigidity of the cylindrical portion having a closed cross-section structure by line welding formed by fillet welding of the lap weld joint structure is replaced by a closed cross-section structure by point fastening formed by bolts. It can be made higher than the rigidity of the cylindrical portion. As a result, in the suspension member of the present embodiment, it is not necessary to form ribs or the like for ensuring rigidity, and the base material can be made thinner with the same rigidity, and the weight of the automobile to which this is applied can be reduced. can be done.

(Third embodiment)
FIG. 4 is a perspective view of the lap weld joint structure according to the 3-2 embodiment in the suspension member according to the 3-1 embodiment of the present invention. Specifically, it is a perspective view of a portion of the suspension member according to the 3-1 embodiment, which is surrounded at the same position as line II shown in FIG. Equivalent components to those described in the first or second embodiment are denoted by the same reference numerals, and descriptions thereof are omitted.

As shown in FIG. 4, the lap welded joint structure 3 of this embodiment includes a first aluminum alloy base material 10, a second aluminum alloy base material 20, and a fillet weld 30 joining them.

The lap weld joint structure 3 of the present embodiment abuts one end of the first mating surface 10A of the first aluminum alloy base material 10 so as to protrude toward the second mating surface 20A of the second aluminum alloy base material 20, It has the 1st convex part 11 interrupted along the extension direction of the meat weld part 30. As shown in FIG. The intermittent first projections 11 in the illustrated example can be provided on the first mating surface 11 without increasing the number of steps during molding by casting the first aluminum alloy base material. Alternatively, the intermittent first projections 11 can be provided by forming the continuous first projections 11 during molding by casting the first aluminum alloy base material, and performing machining separately.

The lap weld joint structure 3 of the present embodiment is formed by being surrounded by the first aluminum alloy base material 10, the second aluminum alloy base material 20, and the fillet weld 30, and in the extending direction of the fillet weld 30 It has a communicating gap 3A.

The lap weld joint structure of the present embodiment includes a fillet weld that joins aluminum alloy base materials together, one aluminum alloy base material having a predetermined protrusion, and the other aluminum alloy base material and the fillet weld. and has a gap communicating in the extending direction of the fillet weld. Therefore, in the lap welded joint structure of the present embodiment, gas such as hydrogen gas generated from the molten metal during welding is introduced through two locations, one end and the other end, of the gap communicating in the extending direction of the fillet weld. It can escape to the outside and reduce the amount of gas in the molten metal. As a result, in the lap welded joint structure of the present embodiment, it is possible to suppress or prevent the occurrence of gas defects such as wormholes that cause deterioration of mechanical properties. Moreover, from the viewpoint of weight reduction, the lap weld joint structure of the present embodiment is preferable to the lap weld joint structure of the first embodiment.

In the lap weld joint structure of the present embodiment, since a plurality of first protrusions 11 are provided in an intermittent state along the extending direction of the fillet weld 30, the first protrusions 11 Compared to the lap weld joint structure of the first embodiment, which is provided in a continuous state along the extending direction of 30, the gas generated from the molten metal is passed between the adjacent first protrusions 11, The gas can be further released to the outside, and the amount of gas in the molten metal can be further reduced. As a result, in the lap welded joint structure of the present embodiment, it is possible to further suppress or prevent the occurrence of gas defects such as wormholes, which may cause deterioration of mechanical properties.

In the lap weld joint structure of the present embodiment, the distance between the first mating surface 10A of the first aluminum alloy base material 10 and the second mating surface 20A of the second aluminum alloy base material 20 is 0.1 mm or more and 2.5 mm. It is preferably 0.3 mm or more and 2.5 mm or less. By setting the height of the intermittent first projections to 0.1 mm or more, the distance between the first mating surface 10A and the second mating surface 20A becomes 0.1 mm or more, which is the same as the height of the first projections, The gas generated from the molten metal can be sufficiently released to the outside through two places, one end and the other end of the gap, and between the adjacent first convex portions, and generation of gas defects such as wormholes that cause destruction. can be further suppressed or prevented. By setting the height of the intermittent first projections to 2.5 mm or less, the distance between the first mating surface 10A and the second mating surface 20A becomes 2.5 mm or less, which is the same as the height of the first projections, It is possible to suppress or prevent deterioration of welding quality caused by molten metal flowing into the gap.

Also in the lap weld joint structure of the present embodiment, the preferred form and material types of the lap weld joint structure of the first embodiment can be appropriately adopted.

The suspension member of the present embodiment includes a tubular portion formed of one aluminum alloy base material having a concave cross-sectional shape and the other aluminum alloy base material, and at least a portion of the tubular portion is the overlapping member of the present embodiment. It has a closed cross-sectional structure formed by a welded joint structure. Therefore, in the suspension member of the present embodiment, the rigidity of the cylindrical portion having a closed cross-section structure by line welding formed by fillet welding of the lap weld joint structure is replaced by a closed cross-section structure by point fastening formed by bolts. It can be made higher than the rigidity of the cylindrical portion. As a result, in the suspension member of the present embodiment, it is not necessary to form ribs or the like for ensuring rigidity, and the base material can be made thinner with the same rigidity, and the weight of the automobile to which this is applied can be reduced. can be done.

(Fourth embodiment)
FIG. 5 is a perspective view of a lap weld joint structure according to a 4-2 embodiment in a suspension member according to a 4-1 embodiment of the present invention. Specifically, it is a perspective view of a portion of the suspension member according to the 4-1 embodiment, which is surrounded at the same position as line II shown in FIG. It should be noted that the same reference numerals as those described in the first to third embodiments are assigned to the same components, and the description thereof will be omitted.

As shown in FIG. 5, the lap welded joint structure 4 of this embodiment includes a first aluminum alloy base material 10, a second aluminum alloy base material 20, and a fillet weld 30 joining them.

The lap welded joint structure 4 of the present embodiment protrudes toward the second mating surface 20A of the second aluminum alloy base material 20 and contacts the middle of the first mating surface 10A of the first aluminum alloy base material 10. It has the 1st convex part 11 interrupted along the extension direction of the meat weld part 30. As shown in FIG. The intermittent first projections 11 in the illustrated example can be provided on the first mating surface 11 without increasing the number of steps during molding by casting the first aluminum alloy base material. Alternatively, the intermittent first projections 11 can be provided by forming the continuous first projections 11 during molding by casting the first aluminum alloy base material, and performing machining separately.

The lap weld joint structure 4 of the present embodiment is formed by being surrounded by the first aluminum alloy base material 10, the second aluminum alloy base material 20, and the fillet weld 30, and in the extending direction of the fillet weld 30 It has a communicating gap 4A.

The lap weld joint structure of the present embodiment includes a fillet weld that joins aluminum alloy base materials together, one aluminum alloy base material having a predetermined protrusion, and the other aluminum alloy base material and the fillet weld. and has a gap communicating in the extending direction of the fillet weld. Therefore, in the lap welded joint structure of the present embodiment, gas such as hydrogen gas generated from the molten metal during welding is introduced through two locations, one end and the other end, of the gap communicating in the extending direction of the fillet weld. It can escape to the outside and reduce the amount of gas in the molten metal. As a result, in the lap welded joint structure of the present embodiment, it is possible to suppress or prevent the occurrence of gas defects such as wormholes that cause deterioration of mechanical properties. Moreover, from the viewpoint of weight reduction, the lap weld joint structure of the present embodiment is preferable to the lap weld joint structure of the second embodiment.

In the lap welded joint structure of the present embodiment, since the first protrusion 11 is provided in the middle of the first mating surface 10A, the first protrusion 11 is provided at one end of the first mating surface 10A. Compared to the lap welded joint structure of the first embodiment, it is less likely to deform due to heat input during welding. Therefore, the lap welded joint structure of the present embodiment is applied when the first convex portion and the fillet welded portion are separated from each other due to the heat input during welding, and the gap dimension greatly changes due to the deformation of the base material. is preferred.

In the lap weld joint structure of the present embodiment, since a plurality of first protrusions 11 are provided in an intermittent state along the extending direction of the fillet weld 30, the first protrusions 11 Compared to the lap weld joint structure of the first embodiment, which is provided in a continuous state along the extending direction of 30, the gas generated from the molten metal is passed between the adjacent first protrusions 11, The gas can be further released to the outside, and the amount of gas in the molten metal can be further reduced. As a result, in the lap welded joint structure of the present embodiment, it is possible to further suppress or prevent the occurrence of gas defects such as wormholes, which may cause deterioration of mechanical properties.

In the lap weld joint structure of the present embodiment, the distance between the first mating surface 10A of the first aluminum alloy base material 10 and the second mating surface 20A of the second aluminum alloy base material 20 is 0.1 mm or more and 2.5 mm. It is preferably 0.3 mm or more and 2.5 mm or less. By setting the height of the intermittent first projections to 0.1 mm or more, the distance between the first mating surface 10A and the second mating surface 20A becomes 0.1 mm or more, which is the same as the height of the first projections, The gas generated from the molten metal can be sufficiently released to the outside through two places, one end and the other end of the gap, and between the adjacent first convex portions, and generation of gas defects such as wormholes that cause destruction. can be further suppressed or prevented. By setting the height of the intermittent first projections to 2.5 mm or less, the distance between the first mating surface 10A and the second mating surface 20A becomes 2.5 mm or less, which is the same as the height of the first projections, It is possible to suppress or prevent deterioration of welding quality caused by molten metal flowing into the gap.

Also in the lap weld joint structure of the present embodiment, the preferred form and material types of the lap weld joint structure of the first embodiment can be appropriately adopted.

The suspension member of the present embodiment includes a tubular portion formed of one aluminum alloy base material having a concave cross-sectional shape and the other aluminum alloy base material, and at least a portion of the tubular portion is the overlapping member of the present embodiment. It has a closed cross-sectional structure formed by a welded joint structure. Therefore, in the suspension member of the present embodiment, the rigidity of the cylindrical portion having a closed cross-section structure by line welding formed by fillet welding of the lap weld joint structure is replaced by a closed cross-section structure by point fastening formed by bolts. It can be made higher than the rigidity of the cylindrical portion. As a result, in the suspension member of the present embodiment, it is not necessary to form ribs or the like for ensuring rigidity, and the base material can be made thinner with the same rigidity, and the weight of the automobile to which this is applied can be reduced. can be done.

(Fifth embodiment)
FIG. 6 is a perspective view of the lap weld joint structure according to the 5-2 embodiment in the suspension member according to the 5-1 embodiment of the present invention. Specifically, it is a perspective view of a portion of the suspension member according to the 5-1 embodiment surrounded at the same position as line II shown in FIG. Note that the same reference numerals as those described in the first to fourth embodiments are assigned to the same components, and the description thereof is omitted.

As shown in FIG. 6, the lap weld joint structure 5 of the present embodiment includes a first aluminum alloy base material 10, a second aluminum alloy base material 20, and a fillet weld 30 joining them.

The lap weld joint structure 5 of the present embodiment protrudes toward the first mating surface 10A of the first aluminum alloy base material 10 and abuts on the middle of the second mating surface 20A of the second aluminum alloy base material 20. A continuous convex portion 21 (hereinafter sometimes referred to as “second convex portion 21”) is provided along the extending direction of the meat welded portion 30 .

The lap weld joint structure 5 of the present embodiment is formed by being surrounded by the first aluminum alloy base material 10, the second aluminum alloy base material 20, and the fillet weld 30, and is formed in the extending direction of the fillet weld 30. It has a communicating gap 5A.

The lap weld joint structure of the present embodiment includes a fillet weld that joins aluminum alloy base materials together, one aluminum alloy base material having a predetermined protrusion, and the other aluminum alloy base material and the fillet weld. and has a gap communicating in the extending direction of the fillet weld. Therefore, in the lap welded joint structure of the present embodiment, gas such as hydrogen gas generated from the molten metal during welding is introduced through two locations, one end and the other end, of the gap communicating in the extending direction of the fillet weld. It can escape to the outside and reduce the amount of gas in the molten metal. As a result, in the lap welded joint structure of the present embodiment, it is possible to suppress or prevent the occurrence of gas defects such as wormholes that cause deterioration of mechanical properties.

In the lap welded joint structure of the present embodiment, since the second protrusion 11 is provided in the middle of the second mating surface 20A, the second protrusion is provided at one end of the second mating surface. Therefore, it is difficult to deform due to heat input during welding. Therefore, the lap welded joint structure of the present embodiment is applied when the second convex portion and the fillet welded portion are separated from each other due to the heat input during welding, and the gap dimension greatly changes due to the deformation of the base material. is preferred.

In the lap weld joint structure of the present embodiment, the distance between the first mating surface 10A of the first aluminum alloy base material 10 and the second mating surface 20A of the second aluminum alloy base material 20 is 0.3 mm or more and 2.5 mm. The following are preferable. By setting the height of the continuous second protrusion to 0.3 mm or more, the distance between the first mating surface 10A and the second mating surface 20A becomes 0.3 mm or more, which is the same as the height of the second protrusion. The gas generated from the molten metal can be sufficiently released to the outside through one end and the other end of the gap, and the occurrence of gas defects such as wormholes that cause deterioration of mechanical properties can be further suppressed or prevented. Furthermore, by setting the height of the continuous second protrusion to 2.5 mm or less, the distance between the first mating surface 10A and the second mating surface 20A becomes 2.5 mm or less, which is the same as the height of the second protrusion. Therefore, it is possible to suppress or prevent deterioration of welding quality due to molten metal flowing into the gap.

In the lap welded joint structure of the present embodiment, the second aluminum alloy base material is preferably an aluminum alloy casting. By using an aluminum alloy casting as the second aluminum alloy base material, the second protrusions can be easily provided on the second mating surfaces without increasing the number of steps when forming the second aluminum alloy base material by casting.

Also in the lap weld joint structure of this embodiment, various forms and materials of the lap weld joint structures of the first to fourth embodiments can be appropriately adopted.

The suspension member of the present embodiment includes a tubular portion formed of one aluminum alloy base material having a concave cross-sectional shape and the other aluminum alloy base material, and at least a portion of the tubular portion is the overlapping member of the present embodiment. It has a closed cross-sectional structure formed by a welded joint structure. Therefore, in the suspension member of the present embodiment, the rigidity of the cylindrical portion having a closed cross-section structure by line welding formed by fillet welding of the lap weld joint structure is replaced by a closed cross-section structure by point fastening formed by bolts. It can be made higher than the rigidity of the cylindrical portion. As a result, in the suspension member of the present embodiment, it is not necessary to form ribs or the like for ensuring rigidity, and the base material can be made thinner with the same rigidity, and the weight of the automobile to which this is applied can be reduced. can be done.

EXAMPLES The present invention will be described in more detail below with reference to Examples, but the present invention is not limited to these Examples.

(Examples 1-1 to 1-28)
By casting the aluminum alloy, a plate-like aluminum alloy base material (thickness: 3 mm or more) made of an aluminum alloy cast material having continuous projections (overall length: 100 mm, height: 3 mm) was obtained. In addition, as shown in FIG. 3, a continuous convex portion was formed at a position shifted by 8 mm toward the intermediate side of the mating surface from the end of the plate-like aluminum alloy base material. The height of the continuous convex portion of the obtained plate-shaped aluminum alloy base material was adjusted by 0.1 mm by 0.1 mm to 0.1 to 2.8 mm by machining, and the plate-shaped aluminum alloy casting material used in each example prepared a first aluminum alloy base material. A plate-like second aluminum alloy base material (thickness: 3 mm) made of an aluminum alloy wrought material used in each example was prepared. The first aluminum alloy base material and the second aluminum alloy base material used in each example were joined by fillet welding by MIG welding to obtain the lap weld joint structure of each example.

(Examples 2-1 to 2-28)
By casting the aluminum alloy, a plate-like aluminum alloy base material (thickness: 3 mm or more) made of an aluminum alloy cast material having continuous projections (overall length: 100 mm, height: 3 mm) was obtained. In addition, as shown in FIG. 3, a continuous convex portion was formed at a position shifted by 8 mm toward the intermediate side of the mating surface from the end of the plate-like aluminum alloy base material. The continuous projections of the obtained plate-shaped aluminum alloy base material were machined into discontinuous projections as shown in FIG. A plate-shaped first aluminum alloy base material made of an aluminum alloy cast material used in each example was prepared by adjusting the thickness by 1 mm. A plate-shaped second aluminum alloy base material (thickness: 3 mm) made of an aluminum alloy wrought material used in each example was prepared. The first aluminum alloy base material and the second aluminum alloy base material used in each example were joined by fillet welding by MIG welding to obtain the lap weld joint structure of each example.

(Comparative example 1)
By casting the aluminum alloy, a plate-like aluminum alloy base material (thickness: 3 mm or more) made of an aluminum alloy cast material having continuous projections (overall length: 100 mm, height: 3 mm) was obtained. In addition, as shown in FIG. 3, a continuous convex portion was formed at a position shifted by 8 mm toward the intermediate side of the mating surface from the end of the plate-like aluminum alloy base material. The height of the continuous convex portion of the obtained plate-shaped aluminum alloy base material was adjusted to 0 mm by machining to prepare the first plate-shaped aluminum alloy base material made of the cast aluminum alloy material used in this example. . A plate-shaped second aluminum alloy base material (thickness: 3 mm) made of a wrought aluminum alloy material used in this example was prepared. The first aluminum alloy base material and the second aluminum alloy base material used in this example were joined by fillet welding by MIG welding to obtain the lap weld joint structure of this example. Table 1 shows part of the specifications of each of the above examples.

<Observation of wormholes>
The occurrence of wormholes in the lap welded joint structure of each example was observed by an X-ray transmission test. Specifically, in the X-ray transmission test, X-ray CT (MCN101 manufactured by PHILIPS) was used, and the voltage was 48 KV, the current was 15 mA, the irradiation time was 1 minute, the distance to the workpiece was 1200 mm, and the illumination was 2.0. The obtained results are also shown in Table 1. The "distance between mating surfaces" in Table 1 means the distance between the mating surface of one aluminum alloy base material and the mating surface of the other aluminum alloy base material. In addition, "Yes" in "Wormhole Occurrence State" in Table 1 indicates a case where relatively many wormholes (linear defects) having a maximum length of 14 mm or more were observed. Furthermore, "Less than Comparative Example 1" in "Wormhole occurrence state" in Table 1 indicates the case where a wormhole (linear defect) having a maximum length of 14 mm or more was observed. "None" in "Wormhole occurrence state" in Table 1 indicates the case where only wormholes (linear defects) having a maximum length of less than 14 mm were observed.

From Table 1, Examples 1-1 to 1-28 and Examples 2-1 to 2-28 belonging to the scope of the present invention have lower mechanical properties than Comparative Example 1 outside the present invention. It can be seen that the occurrence of gas defects such as wormholes, which are factors, can be suppressed or prevented. The lap weld joint structure includes a fillet weld that joins the aluminum alloy base metals together, and one aluminum alloy base material having a predetermined convex portion and the other aluminum alloy base metal and the fillet weld. It is believed that this is because there is a gap that is surrounded and communicates in the extending direction of the fillet weld.

From Table 1, Examples 1-3 to 1-28, which belong to the scope of the present invention, have wormhole-like structures that cause deterioration of mechanical properties more than Examples 1-1 to 1-2. It can be seen that the occurrence of gas defects can be suppressed or prevented. This is because the distance between the first mating surface of the first aluminum alloy base material and the second mating surface of the second aluminum alloy base material is 0.3 mm or more when the predetermined convex portion is a continuous convex portion. 0.5 mm or less. Further, when the predetermined protrusions are intermittent protrusions, the distance between the first mating surface of the first aluminum alloy base material and the second mating surface of the second aluminum alloy base material is 0.1 mm or more. It can be seen that even if the thickness is 5 mm or less, the occurrence of gas defects such as wormholes, which cause deterioration of mechanical properties, can be suppressed or prevented.

In addition, Examples 1-1 to 1-25 and Examples 2-1 to 2-25 belonging to the scope of the present invention are Examples 1-26 to 1-28 and Examples 2-26 As compared with Example 2-28, almost no molten metal flowed into the gap, and deterioration of welding quality could be suppressed or prevented.

In Examples 1-1 to 1-28 and Examples 2-1 to 2-28, which belong to the scope of the present invention, projections could be easily formed in aluminum alloy casting.

Although the present invention has been described with some embodiments and examples, the present invention is not limited to these, and various modifications are possible within the scope of the present invention.

In the above-described embodiment, the case where the first aluminum alloy base material has a concave cross-sectional shape was exemplified, but the present invention is not limited to this. For example, the second aluminum alloy base material may have a concave cross-sectional shape, or both the first and second aluminum alloy base metals may have concave cross-sectional shapes.

In the above-described embodiment, the lap weld joint structure is applied to an automobile suspension member as an example, but it is not limited to this. A closure comprising a cylindrical portion formed of one aluminum alloy base material having a concave cross-sectional shape and the other aluminum alloy base material, at least a portion of the cylindrical portion being formed by the lap weld joint structure of the present invention. If it has a cross-sectional structure, it can be applied, for example, to structural members for various automobiles.

1, 2, 3, 4, 5: Lap weld joint structures 1A, 2A, 3A, 4A, 5A: Gap 10: First aluminum alloy base material (one aluminum alloy base material)
10A: First mating surface (mating surface)
11: First convex portion (convex portion)
20: Second aluminum alloy base material (other aluminum alloy base material)
20A: Second mating surface (mating surface)
21: Second convex portion (convex portion)
30: Fillet weld 100: Suspension member 110: Cylindrical part 111: Closed cross-section structure

Claims (4)

A lap weld joint structure having a fillet weld that joins aluminum alloy base materials together,
The mating surface of one aluminum alloy base material has a convex portion that protrudes toward and contacts the mating surface of the other aluminum alloy base material and is continuous or intermittent along the extending direction of the fillet weld,
A lap weld joint structure, characterized in that it is formed by said one aluminum alloy base material, said other aluminum alloy base material, and said fillet weld, and has a gap communicating in the extending direction of said fillet weld. . When the mating surface of the one aluminum alloy base material has a convex portion that protrudes toward and contacts the mating surface of the other aluminum alloy base material and is continuous along the extending direction of the fillet weld , the distance between the mating surface of the one aluminum alloy base material and the mating surface of the other aluminum alloy base material is 0.3 mm or more and 2.5 mm or less,
When the mating surface of the one aluminum alloy base material has a convex portion that protrudes toward and contacts the mating surface of the other aluminum alloy base material and is intermittent along the extending direction of the fillet weld. The lap welding according to claim 1, wherein the distance between the mating surface of the one aluminum alloy base material and the mating surface of the other aluminum alloy base material is 0.1 mm or more and 2.5 mm or less. joint structure. The lap weld joint structure according to claim 1 or 2, wherein said one aluminum alloy base material is an aluminum alloy casting. A suspension member having a tubular portion formed of one aluminum alloy base material having a concave cross-sectional shape and the other aluminum alloy base material,
A suspension member, wherein at least part of said tubular portion has a closed cross-sectional structure formed by the lap welded joint structure according to any one of claims 1 to 3.

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