JP5444029B2 - Method for manufacturing composite reinforcing member and composite reinforcing member - Google Patents

Description

  The present invention relates to a manufacturing method by welding of a composite reinforcing member in which a steel plate and an aluminum alloy hollow profile are combined, and the manufactured composite reinforcing member.

  In order to reduce the weight, an aluminum alloy hollow shape material is often used as a reinforcing member such as a bending strength member in a vehicle body such as an automobile. Examples of the bending strength member include a bumper reinforcing material (also referred to as bumper reinforcement or bumper armature), a door beam, or a frame member. This bending strength member is required to absorb the energy of externally applied load (external force) by the member's own bending deformation and cross-sectional deformation (lateral crushing) to protect the vehicle body.

  The aluminum alloy hollow shape member used for these bending strength members basically includes a front side flange that receives a bending load, a rear side flange that becomes a tensile side when the bending load is applied, and two parallel to each other. It has a rectangular cross section (mouth cross section) composed of two parallel webs that connect between the flanges. In many cases, this rectangular cross section has, for example, a daily cross-sectional shape in which one intermediate rib is provided in parallel with the web and reinforced. This aluminum alloy hollow profile is manufactured by hot extrusion and tempering treatment (heat treatment) of high-strength aluminum alloys such as 6000 series and 7000 series, and has the above-mentioned uniform shape of the cross section in the longitudinal direction. It is a feature. Hereinafter, this aluminum alloy hollow shape member is also simply referred to as a hollow shape member.

  If a composite reinforcing member in which a relatively thin high-strength steel plate (high-tensile steel plate) is laminated and integrated with such an aluminum alloy hollow shape material, the reinforcing effect is increased without a significant increase in weight. Can do. That is, if a thin steel plate is laminated and reinforced on the back region of the rear side flange, which is the tension side when a bending load is applied, on the side opposite to the front side flange, the bending load applied to the steel plate is shared. Can take charge. Therefore, by sharing the bending load to which the steel plate is loaded, excessive deformation of the aluminum alloy hollow profile can be suppressed, and original energy absorption due to the deformation of the rectangular cross-section structure of the hollow profile can be caused.

  However, as is well known, when these steel plates and aluminum alloy hollow shapes are joined by welding, a reaction layer made of a brittle Fe-Al intermetallic compound is likely to be formed at the joint (interface). Since the steel sheet has a higher melting point, higher electric resistance, and lower thermal conductivity than the aluminum alloy hollow profile, the low melting point aluminum side first melts. Next, the surface of the steel plate is melted, and as a result, a Fe—Al-based brittle intermetallic compound layer is formed at the interface. For this reason, it has been very difficult to obtain a reliable joint having high strength (joint strength).

  On the other hand, mechanical joints represented by self-piercing rivets are used to join these dissimilar metal materials (dissimilar materials), compared to welded joints, the reliability of joints and new equipment. In addition, there are major problems such as increased labor and joining costs due to the need for the number of parts. In addition, there is a disadvantage that mechanical joining can only be point joining.

  Incidentally, instead of this steel plate, a fiber reinforced resin material (FRP) reinforced with inorganic fibers such as carbon fiber and glass fiber, organic fibers such as Kepler, etc., on the rear side of the rear surface side flange of the aluminum alloy hollow shape member. A technique for reinforcing a composite member by providing a material is also known. However, compared with the steel plate, there are practical problems that the reinforcing effect is small or the cost increases even if the reinforcing effect is sufficient.

  Conventionally, many studies have been made on a method for joining dissimilar materials with a long weld line extending in the longitudinal direction of a member by arc welding (melt welding) between a steel material and an aluminum alloy material. For example, in arc welding (melt welding) for joining at higher temperatures, a solid wire made of an aluminum alloy to which at least silicon is added in an amount of 3 to 15 wt% is used as a welding wire, and a steel material having an aluminum alloy material and galvanized surface applied to the surface. Has been proposed (see Patent Document 1). In this method, along with the melting of the welding wire, silicon is also transferred to the base material, penetrates into the molten pool interface, becomes hot due to the heat of the arc, improves the wettability of the molten metal, and improves the adhesion. .

  It has also been proposed to improve the strength of the welded joint by improving the composition of the flux used for arc welding. As an example of this, iron (steel) is made of a flux-cored wire formed by covering a flux containing fluoride (cesium fluoride, aluminum fluoride, potassium fluoride and aluminum oxide) with aluminum or an aluminum alloy. There has been proposed a method of arc welding an aluminum alloy material (see Patent Document 2).

  In addition, steel and aluminum are applied by various welding methods using and applying a fluoride-based mixed flux containing at least one of cesium fluoride, aluminum fluoride, potassium fluoride, and zinc fluoride, such as potassium fluoride and aluminum fluoride. There has been proposed a welding method in which an alloy material is joined to a different material (see Patent Document 3). These methods promote the cleaning action of the steel surface by the chemical reaction of the flux, improve the wettability and adhesion of the molten metal made of aluminum, and prevent the formation of a fragile thick intermetallic compound layer.

  Further, a fluoride-based flux having an effect of reducing, dissolving and removing the oxide film from the surface of the aluminum alloy material on which a strong oxide film is formed is applied to the surface of the aluminum alloy material, so that mild steel and 6000 series aluminum alloy material are applied. A method of spot welding is proposed (see Patent Document 4). These fluoride fluxes are also used for fusion welding between aluminum alloy materials (see Patent Documents 5 and 6).

  However, in the welding method using these fluxes, there is a problem that high joint strength cannot be obtained by wire welding between different high strength materials such as the high-strength steel material and 6000 series aluminum alloy material. For this reason, the MIG welding method and laser brazing utilizing a flux called a nocolok flux, such as a fluoride composition containing aluminum fluoride or a flux containing a fluoride composition not containing chloride, etc. Methods have also been developed (Patent Documents 7 to 10 etc.). In these welding methods, a flux cored wire (hereinafter also referred to as FCW or a flux-cored wire) formed by filling the aluminum material outer shell with a flux is used as a flux supply, thereby improving workability. ing.

JP 2004-223548 A JP2003-2111270A JP 2003-48077 A JP 2004-351507 A JP 2004-210013 A JP 2004-210023 A JP 2007-136524 A JP 2007-136525 A JP 2007-301634 A JP 2008-68290 A

  Certainly, the MIG welding method and the laser brazing method (hereinafter also referred to as the FCW welding method) utilizing the flux-cored wire are very efficient welding methods. However, even in this FCW welding method, when a steel plate is welded to the rear surface of the rear surface side flange of the aluminum alloy hollow shape member, the high bonding strength required as the bending strength member cannot be obtained (cannot be guaranteed). There is a problem peculiar to the bending strength member.

That is, the aluminum alloy hollow shape member having the above-mentioned day-shaped cross-sectional shape is provided with a pair of left and right webs that connect the front and rear flanges as the bending strength member, and the middle portion provided in the center in the rectangular cross section. Transmit shearing force with ribs. For this reason, when laminating steel plates on the back side of the rear surface side flange of the hollow shape member and performing FCW welding, the shear force is transmitted, and two back surface regions on both end sides where the web of the rear side flange intersects. And it is necessary to weld along the longitudinal direction of the hollow profile at a total of three locations, one at the back region on the center side where the middle ribs of the rear surface side flange intersect.
However, although these three places can be welded for the reasons described below, the joint strength is weakened.

  First, in order to FCW weld the aluminum alloy and the steel plates to each other in the back region on the center side of the rear side flange where the middle ribs intersect, welding from the laminated steel plate side as it is is an aluminum alloy in the lower layer. The side is not exposed and is inevitably impossible. Therefore, it is necessary to provide a space to expose the aluminum alloy and perform overlap fillet welding in the same manner as the two back regions on both ends of the rear flange on which the web intersects, which is the point of overlap fillet welding. There is.

  For this reason, usually, the steel plates to be laminated are divided into two, and a gap (space) is provided in the back region on the center portion side where the middle ribs of the rear side flanges of the hollow shape members intersect, and the steel plates are laminated. That is, each side surface facing the central portion side of the laminated steel plates and the back region on the central portion side of the rear surface side flange of the hollow shape member in the gap, one at a time, a total of two locations, the overlap It will be welded in the manner of fillet welding. However, in such a welding joining method, the respective welding lines on the side surfaces facing the center side of the steel plates come close to each other. This is because the thickness of the hollow profile webs and intermediate ribs is only about a few millimeters, and there is a great limit to the distance between the weld lines on the center side of the steel plates.

  That is, if the aluminum alloy side is melted by the first welding on the one side of the steel plate on either side, the shape of the weld joint becomes unstable during the second welding on the center side of the other steel plate. Further, if the second weld bead overlaps the weld bead portion formed by the first welding, a poor penetration is likely to occur. Further, due to the thermal strain accompanying the first welding, the joint shape (gap or gap between the steel plates) changes, and the second welding becomes more unstable. Furthermore, by performing two close weldings at the center of the rear side flange, the thermal strain after welding increases, which adversely affects the shape of the reinforcing member. Further, as described above, when the steel plate is divided into two sheets, the length of the weld line is simply doubled, so that there is a problem that the welding cost is also doubled.

  Further, the rear surface side flange is formed by combining a side surface portion on the center portion side of each of the two steel plates facing a rear region on the center portion side of the rear surface side flange and a gap portion between the steel plates of the rear surface side flange. It is also conceivable that welding is integrally performed as a welding portion on the center side where the middle ribs intersect. However, in this case, it is necessary to weld the two steel plates and the aluminum alloy at a time, and as the heat input increases, the aluminum alloy side is likely to be melted, and the lap fillet welding construction itself is difficult. Have difficulty.

  Further, in the rear flange of the aluminum alloy hollow profile, welding in the longitudinal direction of two back regions on both end sides where the web intersects is also possible, but both sides of the steel plate (the above-mentioned Since both sides of the aluminum alloy hollow profile are open, high bonding strength cannot be expected. In other words, there is no welding in the back region on the center side of the rear side flange where the middle ribs intersect, and only welding in the two back regions on both ends is required as the bending strength member. Bonding strength cannot be obtained.

  For the above reasons, it is quite difficult to manufacture a composite reinforcing member by welding a steel plate to the back side of the rear surface side flange of the aluminum alloy hollow material, and even if it is welded, it is required as the bending strength member, which is a high joint. Strength cannot be obtained and cannot be guaranteed.

  In view of such a problem, the present invention provides a composite reinforcing member that can obtain a high joint strength required as the bending strength member even when a steel plate is welded to the rear surface of the rear surface side flange of the aluminum alloy hollow shape member. It aims at providing a manufacturing method and a composite reinforcement member.

In order to achieve the above object, the gist of the manufacturing method of the composite reinforcing member of the present invention is that when a bending load is applied to an aluminum alloy hollow shape member having a daily cross-sectional shape with an intermediate rib in a rectangular cross-section. A steel plate is laminated on the back side of the rear side flange to be the tension side, and the laminated steel plate and the aluminum alloy hollow profile are centered at both ends of the rear side flange and the middle rib of the rear side flange. The three parts of the aluminum alloy hollow shape member are joined together using the aluminum alloy filler material by lap fillet arc welding in the longitudinal direction of the aluminum alloy hollow shape member at three locations on the part side. The back surface region on the center portion side where the middle ribs of the rear flange intersect is formed in advance in the longitudinal direction of the aluminum alloy hollow shape member, and the back surface formed in this convex shape In this state, the rear surface side flange is formed by laminating the two steel plates so as to sandwich the region therebetween, and the rear region formed in this convex shape satisfies the following conditions and protrudes between the steel plates. The rear region formed in a convex shape and the side surface portion on the central portion side of each of the two steel plates facing this rear region are welded on the central portion side where the middle rib of the rear flange intersects As a place, it is welding to the said side surface of the said steel plate, and the surface which follows it over the longitudinal direction of the said aluminum alloy hollow shape material.
Here, the conditions that the convexly formed back region satisfies are that the maximum thickness of the aluminum alloy hollow profile is 8 mm or less, and the plate thickness of the steel sheet is in the range of 0.3 to 4.0 mm. when, before Symbol rear region formed in a convex shape, the area S of the longitudinal section in the upper side region than the upper surface level of the steel sheet by 10 mm ² or less, the back and flush the root portion of the rear surface side flange The width L1 of the rear end portion, which is the length in the width direction of the hollow shape member, is 8 mm or less, and the ratio L1 / tw between the L1 and the width tw of the middle rib is 0.6 or more and 1.2 or less ( However, the width tw of the middle rib is 8 mm or less).

  Here, it is preferable that the welding is MIG welding or laser welding using a flux cored wire in which a flux is filled inside the aluminum outer shell.

In order to achieve the above object, the gist of the composite reinforcing member of the present invention is a composite reinforcing member manufactured by each of the above manufacturing methods, and has a daily cross-sectional shape in which a middle rib is provided in a rectangular cross section. A steel plate is laminated on the back side of the rear side flange, which becomes the tension side when the bending load of the aluminum alloy hollow shape is applied, and the laminated steel plate and the aluminum alloy hollow shape member are connected to the rear side flange. Aluminum alloy filler by overlapped fillet arc welding in the longitudinal direction of the aluminum alloy hollow shape at three locations, both ends and the central side where the middle rib of the rear flange intersects The aluminum alloy hollow shape member is joined to the back surface region on the center side where the intermediate ribs of the rear surface side flange of the aluminum alloy hollow shape member intersect with each other. A convex back surface region formed in advance in the direction is provided so as to protrude between the two steel plates laminated so as to sandwich the convex back surface region therebetween. A convex back region and a side portion on the center portion side of each of the two steel plates facing the back region are combined, and as a welding portion on the center portion side where the middle rib of the rear surface side flange intersects, The bead is covered with the aluminum alloy bead in a longitudinal direction of the hollow shape of the aluminum alloy, and is integrally joined to the side surface of the steel plate and the subsequent surface .

  The reason why the high joint strength required as the bending strength member cannot be obtained when the aluminum alloy hollow shape member and the steel plate are welded using the FCW welding method is only due to the difficulty of the welding operation described above. In addition, it depends on the relationship between the specific use of the bending strength member and the specific cross-sectional shape of the hollow cross-sectional shape of the sun.

  In the daily section, the shear force (impact load) received by the flange on the front side is transmitted to the rear side flange by the webs at both ends of the flange and the middle rib at the center of the flange. For this reason, as a composite reinforcing material, it is effective to provide weld lines in the longitudinal direction of the hollow shape material at three locations near the middle ribs in the central portion along with the webs at both ends.

  However, in this case, in particular, the center side where the middle ribs of the rear surface side flange intersect with each other than the back surface region (near each web of the both end portions) where the webs on both end sides of the rear surface side flange intersect. The load applied to the rear region (near the central rib in the center) increases. For this reason, when the bending load by the vehicle body collision of a motor vehicle acts, it becomes easy to destroy especially the welding part of the back surface area | region of the center part side of the said rear surface side flange.

  Accordingly, the welded portion in the rear region on the center side of the rear flange is particularly required to have a bonding strength. As described above, the welded portion intersects the webs on both ends of the rear flange. This is a place where it is significantly more difficult to carry out the overlap fillet welding than the welded portion in the back region.

  On the other hand, in this invention, as the said summary, while forming the back area | region of the center part side of the said rear surface side flange of the said hollow shape material joined beforehand in convex shape, this back area formed in this convex shape (Protrusions) sandwiched between them, the steel plates are laminated so as to protrude between the two steel plates on which the convex portions are laminated, and the back region formed in this convex shape, and the 2 facing the back region The steel sheet is joined together with the side surface portion on the center side of each of the steel plates.

  In the present invention, as described above, in a state where the projections and projections of the hollow shape member project between the two steel plates on which the projections are laminated, the projections and depressions of the steel plate central portion side are engaged, The meshing area is integrated, and an aluminum alloy filler material is used, and the fillet arc welding is performed over the longitudinal direction of the hollow profile and covered with an aluminum alloy bead.

  For this reason, as will be described later, due to the effect of projecting the convex shape of the hollow profile upward from the steel plate, the spread of the molten aluminum is optimized, and the supply of flux to the steel plate joint surface is also sufficient, The effect of improving the wettability between molten aluminum and steel is increased.

  As a result, it is possible to form a bead made of an aluminum welding material that extends over both the steel plate and the hollow profile. Thereby, in this invention, when welding the said hollow shape material and a steel plate using the said FCW welding method, high joint strength can be ensured stably also in the welding location where the load loaded is large.

It is a perspective view which shows the one aspect | mode of this invention, and shows the state before laminating | stacking an aluminum alloy hollow shape material and a steel plate. It is a perspective view which shows the one aspect | mode of this invention, and shows the laminated | stacked state before welding an aluminum alloy hollow shape material and a steel plate. FIG. 3 is an enlarged view of a main part of FIG. 2. It is a side view which shows the one aspect | mode of this invention and shows the composite reinforcement member after welding the aluminum alloy hollow shape material and the steel plate. It is a perspective view which shows the one aspect | mode of this invention and shows the composite reinforcement member after welding. It is a top view which shows the usage condition of the composite reinforcement member of FIG.

  The embodiment of the present invention and the significance of each requirement of the present invention will be specifically described below with reference to the drawings.

  The manufacturing method of a composite reinforcement member is demonstrated in order using FIGS. In FIG. 1, the state before laminating | stacking the aluminum alloy hollow shape material 2 and the steel plates 10 and 11 is shown with a perspective view. Moreover, the state after laminating | stacking the aluminum alloy hollow shape material 2 and the steel plates 10 and 11 in FIG. 2 is shown with a perspective view. In FIGS. 1 and 2 and FIG. 4 to be described later, the bending load at the time of an automobile body collision indicated by F from the lower side of each figure toward the upper front side flange 3 is indicated by an arrow.

  In the embodiments of FIGS. 1, 2, and 4, the lengths of the steel plates 10 and 11 to be laminated and bonded to the hollow shape member 2 are the same, but the lengths of the steel plates 10 and 11 are selected as necessary and are not necessarily hollow. The length need not be the same as the length of the profile 2 and may be shortened. If the lengths of the steel plates 10 and 11 are made shorter than the length of the hollow shape member 2, there is also an advantage that the weld line to be joined to the different material can be shortened.

  The hollow shape member 2 includes a front side flange (front wall) 3 that becomes a compression side when a bending load F acts, a rear side flange (rear wall) 4 that becomes a tension side, and two flanges that are parallel to each other. A rectangular cross section is formed from two webs (horizontal walls) 5 and 6 that are connected to each other between 3 and 4 and are parallel to each other. Further, in this rectangular cross section, a middle cross section 7 parallel to the webs 5 and 6 is provided at the central part of the flanges 3 and 4 (intermediate part between the webs 5 and 6) to have a daily cross section shape. .

  As the cross-sectional shape of the hollow shape member 2, a mouth shape, an eye shape, a rice field shape, and the like are also known. However, in the present invention, the manufacturing method (welding method) of the present invention can be applied, and the weight can be increased (reinforced) from the cross-sectional shape of the mouth without increasing the weight. Select the cross-sectional shape.

(Formation of convex region)
Characteristically, the hollow shape member 2 has a convex shape (protruding shape) in which the rear region 4a on the center side of the rear surface side flange 4 where the intermediate ribs 7 intersect is extended in the longitudinal direction of the hollow shape member 2. ).

  As shown in FIG. 2, two steel plates 10 and 11 are laminated on the back surface 9 of the rear surface side flange 4 of the hollow shape member 2 so as to sandwich the convex back surface region (projection) 8 therebetween. In this case, the convex region 8 (the rear region 8 formed in a convex shape, hereinafter simply referred to as the convex portion 8) is formed between the steel plates 10 and 11, and the tip 8a is preferably a steel plate. It protrudes above the upper surface of 10 and 11.

  In FIG. 2, in the hollow profile 2 on the lower side of the steel plates 10, 11, the vertical position (level) of the tip 8 a of the projection (projection) 8 is the longitudinal direction of the hollow profile 2, which is the welding direction. In the direction, it protrudes by a length of X mm above the vertical position (level indicated by the dotted line) of the steel plate welding surface which is the surface (upper surface) of the steel plates 10 and 11. In other words, as shown in FIG. 3, the shape conditions of the size and height of the convex portion 8 are determined so that the tip 8a of the convex portion 8 protrudes by X mm above the surfaces of the steel plates 10 and 11. ing. Here, in order to obtain the effect described later, the optimum range of the protrusion amount X above the surface level of the steel plates 10 and 11 of the convex portion 8 varies depending on various conditions as described later. In the field of reinforcing members, the range is 0.5 mm to 5 mm.

  Thus, when the front-end | tip 8a of the convex part 8 used as the welding surface of the hollow shape material 2 is made to protrude above the position of the welding surface of the surface (upper surface) of the steel plates 10 and 11, the said hollow shape material 2 of FIG. At least the weld surface of the hollow profile 2 is above the weld surface of the steel plates 10 and 11 with respect to the welding direction in the longitudinal direction.

  In the present invention, the projections and depressions such that the tip 8a of the convex region (convex part) 8 on the hollow profile 2 side protrudes upward from the surface of the two steel plates 10 and 11 stacked. In this state, the meshing area is integrated, and an aluminum alloy filler material is used, and the fillet arc welding is performed over the longitudinal direction of the hollow member 2 and covered with an aluminum alloy bead.

  As a result, as shown in FIG. 4, the steel plate center side end portions 10a and 11a and the hollow profile are also formed at the welded portion on the center side where the middle rib 7 of the rear surface side flange 4 intersects by overlap fillet welding. A good bead 12 made of an aluminum welding material over both welding surfaces with the back region 4a on the center side of 2 can be formed. As a result, when the hollow shape member 2 and the steel plates 10 and 11 are welded using the FCW welding method, a high joint strength can be stably obtained even at the welded portion of the back region 4a on the center side of the hollow shape member 2. Can be secured.

  More specifically, the spread of the molten aluminum is optimized at the welded portion of the back region 4a on the center side where the middle ribs 7 of the rear surface side flange 4 intersect, and the supply of flux to the steel plate joint surface is sufficient. Therefore, the effect of improving the wettability between the molten aluminum and the steel is increased. That is, as shown in FIG. 4, the molten aluminum 6 (becomes a bead) from the welding surface (the tip 8 a of the convex portion 8) of the hollow shape member 2 on the upper side is the surface (welding surface) of the lower steel plates 10 and 11. ) Easy to spread. This is also true for the flux supplied to the weld surface. Therefore, even when the flux is utilized (in the case of the FCW welding method), the flux tends to spread on the surfaces (welded surfaces) of the lower steel plates 10 and 11. For this reason, the wettability of the welding surface of the steel plates 10 and 11 and the molten aluminum can be improved, and the removal of the oxide film on the surfaces (welding surfaces) of the steel plates 10 and 11 can be promoted. As a result, the bead 12 made of the aluminum welding material over both the steel plate welding surface and the aluminum alloy hollow profile welding surface can be formed, and good dissimilar material joining can be realized.

  On the other hand, the molten aluminum is widely covered on the welded surfaces of the steel plates 10 and 11 by the cleaning action, the wettability and the adhesion improving action by the flux, and is in a close contact state. Therefore, the steel plates 10 and 11 are not directly input heat from the arc, but are indirectly input through the aluminum melt covered. For this reason, the steel plates 10 and 11 are not heated and melted excessively by the arc, and a thin intermetallic compound layer of about several μm is formed at the bonding interface with the molten aluminum that is in close contact. When this intermetallic compound layer becomes thicker than about several tens of μm, it becomes brittle and weld cracks occur and the strength deteriorates. However, a thin intermetallic compound layer of about several μm is not brittle and has a strong bonding state. It becomes.

(Basic structure of composite reinforcing member)
FIG. 5 shows how the composite reinforcing member shown in FIG. 4 is used. FIG. 5 shows a composite reinforcing member shown in FIG. 4 showing a direction during welding as a bumper reinforcing material, with the front side flange 3 and the rear side flange 4 arranged in the front-rear direction of the automobile body, and the longitudinal direction of the composite reinforcing member shown in FIG. It extends in the width direction.

  As shown in FIG. 5, the composite reinforcing member 1 finally produced in the present invention has the steel plate 10, 11 stacked side by side on the back surface 9 of the rear surface side flange 4 of the aluminum alloy hollow shape member 2 having a daily cross-sectional shape. Reinforced by welding. These steel plates 10 and 11 and the hollow shape member 2 are the central portions of the rear surface side flange 4 where the intermediate ribs 7 intersect with the back surface regions 4b and 4c on the both end sides of the rear surface side flange 4 where the webs 5 and 6 intersect. Three aluminum alloy beads 12 (center side), 13 (end side), and 14 (end side) in the longitudinal direction of the hollow shape member 2 with the three backside regions 4a as welding locations They are covered and joined together.

  As described above, in the case of a Japanese section, the shear force (impact load) F indicated by the arrow from the left direction received by the front side flange 3 is set to f1 and f3 from the webs at both ends of the flange, so that As f2 from the rib, it is shared and transmitted to the rear surface side flange 4. In this case, in particular, the middle rib 7 of the rear surface side flange 4 is larger than the loads f1 and f3 on the rear regions (near the webs on both ends) 4b and 4c where the webs on both ends of the rear surface side flange 4 intersect. The load f2 applied to the intersecting back side region (near the middle rib in the center) 4a increases. For this reason, when a bending load is applied due to a vehicle body collision of an automobile, the aluminum alloy bead 12 (center side), which is a welded portion of the rear region 4a on the center side of the rear flange 4 is particularly easily broken. Become.

  On the other hand, in this invention, especially the joining strength of the aluminum alloy bead 12 (center part side) which is a welding part of the back surface area | region 4a of the center part side of this rear surface side flange 4 is excellent. For this reason, two welded portions in the rear regions 4b and 4c on both ends of the rear flange 4 where the webs 5 and 6 intersect, that is, aluminum alloy beads 13 (end side) and 14 (end side) As described in the paragraph 0020, even if the joint strength is relatively low, a high joint strength required as the bending strength member can be obtained.

  As described above, in the present invention, when the hollow shape member 2 and the steel plates 10 and 11 are welded using the FCW welding method, the welding operation is difficult even at the welding portion of the back region 4a on the center side. Greatly improved. As a result, high joint strength can be stably ensured even at the welded portion of the back region 4a on the center side, where the applied load, which is specific to the shape of the sectional shape of the sun, is particularly large. As a result, even if the joint strength of the other two welds in the rear regions 4b and 4c on the both ends of the rear flange 4 where the webs 5 and 6 intersect is relatively low, The required high bonding strength can be obtained.

  As shown in FIG. 6 (a) in plan view (plan view), the bending load of the bending strength member 1 (hollow shape member 2) is the one that supports the bending load at the beginning when the bending load is applied. This is a bending deformation with the portion (center portion 15) loaded with the center being the bending center (bending portion). In this respect, since the composite reinforcing member 1 manufactured in the present invention has excellent bonding strength between the steel plates 10 and 11, the reinforcing effect of the aluminum alloy hollow profile 2 by the steel plates 10 and 11 is sufficiently exhibited.

  As a result, when a bending load due to a vehicle collision is applied, the bending strength member 1 (hollow profile 2) is prevented from being crushed and deformed in cross section, and the bending deformation of the member itself and the cross-sectional direction of the member against the applied bending load are prevented. Energy is absorbed by deformation (lateral collapse). In other words, the original cross-section of the bending strength member 1 efficiently bears stress, and the original energy absorption due to the original deformation of the rectangular cross-section structure occurs. Therefore, the strength and energy absorption amount of the bending strength member can be increased.

  On the other hand, in the conventional joining method of the steel plate to the back surface of the rear surface side flange 4 of the hollow shape member 2, in particular, the aluminum alloy bead 12 (center portion of the welded portion of the back surface region 4 a on the center portion side of the rear surface side flange 4. Side) joint strength is poor. For this reason, when a bending load due to a vehicle body collision is applied, the welded portion is broken, and the reinforcing effect of the hollow shape member 2 by the steel plate is not sufficiently exhibited.

  Therefore, as shown in FIG. 6 (b), the front-side flange 3 and the web 5 (6) on the compression side are quickly brought into contact with the bending strength member 1 (hollow profile 2) central portion 15 to which a bending load is applied. When the local buckling occurs and the deformation further progresses, the front side flange 3 and the web 5 (6) are deformed so as to be remarkably curved, and the crushing deformation of the cross section formed by them progresses. When this cross-sectional deformation progresses, the front side flange 3 and the web 5 (6) are curved, so that a sufficient load cannot be borne. Moreover, since the depth of the cross section is reduced, the resistance moment against bending deformation is reduced, and the bending load is reduced. As a result, the strength and energy absorption amount of the bending strength member are significantly reduced.

(Convex area design method)
As described above, the bending strength member made of the hollow shape member 2 having the shape of the cross section of the sun with the intermediate rib 7 provided in the rectangular cross section has a load transmission to the back surface region of the rear side flange 4 on the tension side. In particular, the load applied to the back region 4a on the center side where the middle rib 7 intersects becomes larger than the back regions 4b and 4c where the webs 5 and 6 on both ends intersect. For this reason, when the bending load by the vehicle body collision of a motor vehicle acts, the welding part of the back surface area | region 4a of the center part side of a rear surface side flange becomes especially easy to be crushed.

  For this reason, the position where the convex region (convex portion) 8 is provided is a welded portion of the back region 4a on the central portion side where the applied load is particularly large as described above. That is, the rear surface side flange 4 of the rear surface side flange 4 of the hollow shape member 2 is defined as a back region 4a on the center side where the ends of the intermediate ribs 7 that transmit the load intersect.

Convex region forming method:
The convex region (convex portion) 8 can be realized by partially thickening the back region 4a on the center side where the end of the middle rib 7 of the rear flange 4 of the hollow profile 2 intersects in advance. . Such partial thickening of the back side region 4a on the central side can be integrated in advance, including the thickened (convex 8) shape, if an aluminum alloy hollow profile is manufactured by hot extrusion. It is easy to form.

Convex area shape:
The shape of the convex region (convex portion) 8 is such that this convex portion on the central portion side is used to obtain a high joint strength by exerting the above-described convex / concave meshing effect at the welded portion of the back region 4a on the central portion side. The conditions are determined from the design conditions on the steel plates 10 and 11 side, the design conditions on the hollow shape member 2 side, the bonding strength required for the composite reinforcing member 1, and the like.

Here, in FIG. 3, the shape of the convex portion 8 is illustrated as a trapezoid, but the shape factor in this case is the vertical cross-sectional area S (mm ² ) of the convex portion 8, the rear end portion of the convex portion 8 ( Width (length) L1 (mm) in the hollow shape width direction of the root portion), width (length) L2 (mm) in the hollow shape width direction of the tip portion of the convex portion 8, and above the steel plate surface level Is the protrusion amount X (mm).

When expressed using the symbols in FIG. 3, the above-described conditions are specifically the following conditions. That is, the conditions satisfied by the convexly formed back region are that the maximum thickness of the aluminum alloy hollow profile 2 is 8 mm or less, and the plate thickness of the steel plates 10 and 11 is 0.3 to 4.0 mm. In the range shown in FIG. 3, the rear surface area (projection) formed in the convex shape has a vertical cross-sectional area S of 10 mm ² or less and a rear end width L 1 of 8 mm or less. The ratio L1 / tw with the width tw of the middle rib satisfies the range of 0.6 or more and 1.2 or less (however, the width tw of the middle rib is 8 mm or less). This condition is common not only when the shape of the protrusion (projection) 8 illustrated in FIG. 3 is a trapezoid, but also when the shape is similar to a rectangle, semicircular shape, or the like.

The vertical sectional area S of the convex portion 8 is the vertical sectional area of only the region on the upper side of the convex portion 8, that is, the steel plates 10 and 11 indicated by dotted lines, as shown by hatching in FIG. It is the area of the longitudinal section of the region above the upper surface level and excluding the lower side from the dotted line (the upper surface level of the steel plates 10 and 11). The vertical cross-sectional area S of this convex part 8 is the back surface area | region 8 (it formed in the convex part by one welding in the shape condition range by the side of the steel plates 10 and 11 mentioned later, and the shape condition range by the side of the hollow shape 2). In order to ensure sufficient penetration of the aluminum alloy material into the region of the convex portion 8 and the protruding portion and the spread of the weld bead to the steel plate, the S is set to 10 mm ² or less.

  The length (width) L1 of the hollow member 2 in the width direction of the rear end portion of the convex portion 8, that is, the base portion flush with the back surface (upper surface) of the rear flange 4 is the projection amount X. And a width (thickness) tw of the middle rib 7 that determines the magnitude of the load applied to the back region 4a on the center side. In addition, considering the thicknesses t1 and t2 on the steel plates 10 and 11 side, the thicknesses t3 and t4 on the rear flange 4 on the hollow profile 2 side, and the welding method, welding apparatus, welding conditions, etc., the convex portion 8 And the width (length) L2 of the front end portion of the convex portion 8 in the width direction of the hollow member are determined.

  In order to ensure sufficient penetration of the aluminum alloy material during welding into the back region 4a on the center side and spread of the weld bead on the steel plates 10 and 11 side (center side surfaces 10a and 11a) with respect to L1. For this, it is preferable that the width of the convex portion 8 (protruding portion) is sufficient with respect to the width (thickness) tw of the middle rib 7 on the hollow shape member 2 side.

  In this regard, when the width tw of the middle rib 7 is 8 mm or less, the width L1 of the rear end portion (root portion) of the convex portion 8 is a ratio L1 / tw to the width (thickness) tw of the middle rib 7; 0.6 or more, more preferably 0.7 or more. If L1 is less than 2 mm or less than 0.6 at L1 / tw, the strength of the joint is insufficient with respect to the strength (load load) of the middle rib 7. On the other hand, if L1 / tw exceeds 1.2 and is too large, the steel plate is too far away from the middle rib 7, so that the reinforcing effect of the steel plate on the portion of the middle rib 7 that requires the most reinforcement is reduced. Therefore, the range of L1 / tw is 0.6 or more and 1.2 or less.

  On the other hand, even if this L1 becomes large, it is possible to cope with a certain range by weaving, but if this L1 exceeds 8 mm, the weaving width becomes too large, the welding heat input becomes too large, The compound grows easily. For this reason, the strength of the joint is insufficient. Moreover, if the width of L1 becomes too large, it is impossible to dispose the L1 sufficiently apart from the weld line on the end side, and a problem of thermal strain during welding is likely to occur. Therefore, if the width (thickness) tw of the middle rib 7 is in the range of 8 mm or less, the width of L1 is 8 mm or less, preferably in the range of 2 to 8 mm, more preferably in the range of 3 to 7 mm.

  The protrusion amount X of the convex portion (protrusion) 8 is preferably 0.5 mm or more and 5 mm or less as described above. The protrusion amount X of the convex portion 8 is appropriately selected according to the design conditions, welding method, welding conditions, etc. of the composite reinforcing member. That is, it is easy to spread to the steel plates 10 and 11 side surface (welding surface) which is the lower side of the convex portion 8 of the molten aluminum, and to the steel plates 10 and 11 side surface (welding surface) which is the lower side of the convex portion 8 of the flux. Is selected as appropriate based on the degree of ease of spreading (improvement of wettability and promotion of removal of oxide film on the steel plate weld surface).

  When this protrusion amount X is small, the molten aluminum does not spread sufficiently on the steel plate side welding surface. On the other hand, when the protrusion amount X is too large, it is difficult to ensure the penetration into the hollow shape member 2 side. Further, if the welding heat input is increased too much to ensure the penetration, the intermetallic compound at the bonding interface grows thick, and in an extreme case, the steel plate side is melted, so it is difficult to ensure the bonding strength. It should be noted that this protrusion amount: Xmm is appropriately designed taking into account the clearance with the steel plates 10 and 11 laminated on the hollow shape member 2 from the upper side (in consideration of the clearance).

  Further, the clearance (gap) C between the surface of the rear surface side flange 4a of the hollow profile 2 and the lower surfaces of the steel plates 10 and 11 stacked from above is minimized. On the other hand, the clearance (gap) G between the rear end portion (root portion) of the convex portion 8 and the central portion side surfaces 10a and 11a of each steel plate has a certain amount of aluminum to the clearance G in order to increase the bonding strength. In order to secure the inflow amount of the alloy material (molten metal), it is preferable to set the range of 0.1 to 2.0 mm per side.

  In the present embodiment, the cross-sectional shape (vertical cross-sectional shape) of the convex portion 8 is a trapezoid, but this may be a rectangle, a semi-elliptical shape, a wave shape, or a combination of these shapes. In any shape, if the hollow shape member 2 is an extruded hollow shape member, the shape of the cross section of the daily shape provided with the convex portions 8 can be easily changed in the longitudinal direction by hot extrusion unless the shape is so complicated. It can be obtained uniformly.

(Thickness of steel plate and aluminum alloy hollow profile)
The plate | board thickness of the steel plate joined by different materials by this invention shall be the range of 0.3-4.0 mm. The thicknesses t1 and t2 on the steel plates 10 and 11 side may or may not be the same, but the maximum thickness is set to 4.0 mm or less from the viewpoint of weight reduction (limit of weight increase). On the other hand, it is 0.3 mm or more from the reinforcing effect of the steel plate. When the thickness of the steel sheet is less than 0.3 mm, the reinforcing effect (compositing effect) of the aluminum alloy hollow shape member 2 cannot be achieved.

  Further, the thicknesses (t3, t4) of the flanges 3 and 4 on the hollow profile 2 side and the widths (thicknesses, tw) of the middle ribs 7 may be the same or not necessarily the same. However, the hollow section 2 itself has a sufficiently high cross-sectional rigidity and strength as a bending reinforcement member, and the problem of thermal distortion due to welding is less likely to occur, and the balance between weight reduction (limit of weight increase) The thickness of the maximum is 8 mm or less. On the other hand, 0.5 mm or more is preferable from the viewpoint of strength (rigidity) required for the reinforcing member, that is, energy absorption at the time of a vehicle collision.

  As shown in FIG. 4, as the composite reinforcing member 1, these steel plates 10 and 11 and the aluminum alloy hollow profile 2 are rear regions where the webs 5 and 6 on both ends of the rear flange 4 intersect. 4b and 4c are welded over the longitudinal direction of the hollow shape member 2 at three locations, that is, the central region side rear surface region 4a where the middle ribs 7 of the rear flange intersect, and are integrally joined.

(Welding method)
The welding shown in FIG. 4 is performed by the length of the steel plates 10 and 11 (the length of the steel plates 10 and 11 is defined as the weld line length) in the longitudinal direction of the hollow profile 2 (steel plates 10 and 11). ), By the lap fillet arc welding method such as FCW. For this purpose, the positional relationship between the steel plates 10 and 11 and the hollow profile 2 is such that the steel plates 10 and 11 are on the upper side and the hollow profile 2 is on the lower side, and the hollow profile 2 is overlapped with each other at the three locations. The fillet is welded along the longitudinal direction.

  In addition, the welding work of the back surface area | regions 4b and 4c where the webs 5 and 6 of the both ends of the rear surface side flange 4 cross | intersect may be as usual. That is, the widths of the steel plates 10 and 11 are made narrower (shorter) than the width of the rear flange 4 so that the aluminum alloy surfaces are exposed in the back regions 4b and 4c. It is set as the shape used as the overlap fillet welding with the side surface 10b, 11b.

  As a result, as a composite reinforcing member joined integrally, as described above, one weld bead 12 is provided at the welded portion of the rear region 4a on the center side of the rear surface side flange 4, and both end portions of the rear surface side flange 4 are provided. Two weld beads 13, 14 are formed along the longitudinal direction of the hollow profile 2 at the welded portions of the rear areas 4 b, 4 c where the side webs 5, 6 intersect.

  The lap fillet arc welding is MIG welding or laser welding using FCW (flux-cored wire, flux-cored wire) filled with flux inside the aluminum outer shell. This is preferable. More specifically, as the arc welding method, DC MIG welding, DC pulse MIG welding, AC MIG welding, AC pulse MIG welding, DC / AC TIG welding, plasma arc welding, arc welding and laser irradiation are simultaneously used. Combined laser irradiation arc welding or the like can be used.

  As the flux cored wire (FCW) for joining different materials used in the present invention, it is preferable to use FCW in which a fluoride-based mixed flux is covered with an aluminum alloy skin in order to improve the efficiency of fusion welding. There are two types of tubular aluminum alloy hoops that fill the inside with a seam with a seam (joint: gap, opening) and a seamless type without a seam where this seam is joined by welding. But either is fine.

  The aluminum alloy used for the FCW shell is not particularly limited, but 4000 series aluminum alloys such as A4043 and A4047 and 5000 series aluminum alloys such as A5356 and A5183 can be used. In addition, aluminum alloys such as 3000 series and 6000 series may be used. Among these, A4043-WY, A4047-WY, A5356-WY, A5183-WY, and the like defined by JIS are preferably exemplified.

  As for the wire diameter of the FCW, an optimum diameter may be selected according to the welding workability including the characteristics of the wire feeder, etc., for welding work used as high-efficiency fully automatic welding or semi-automatic welding. . For example, in the case of MIG welding, general carbon dioxide shielded arc welding, etc., it may be a small diameter of about 0.8 to 1.6 mmφ which is widely used.

  As the wire having a smaller wire diameter is used within the range of the wire diameter, the amount of heat input during welding can be reduced, and the low current condition can be achieved. As a result, scattering of the fluoride-based mixed flux itself can be prevented, welding workability can be improved, and formation of fragile intermetallic compounds can be suppressed. If the wire diameter exceeds 1.6 mm, the current to obtain a stable arc becomes excessive, the scattering of the fluoride-based mixed flux itself increases, the base material melts excessively, and the brittle intermetallic compound May lead to the generation of

  Of course, the filling rate of the flux into the FCW is relatively small, such as about 0.1% by mass or more and less than 24% by mass with respect to the total mass of the FCW, although it depends on the flux composition. A lower filling rate can prevent the flux itself from scattering and improve welding workability. If the filling rate of the flux is too small, the effect of the flux cannot be exhibited, and a sound and highly reliable welded joint cannot be obtained.

  The flux composition used (filled) in the FCW is a mixed flux (nocolock flux) having a specific composition in which fluorides such as aluminum fluoride and potassium fluoride are mixed, among fluoride-based mixed fluxes. It is preferable. Moreover, it is preferable to regulate the amount of chloride to 1 mol% or less or to make a fluoride composition not containing chloride. This is because, when chloride remains in the welded portion, it acts as a corrosion promoting factor for the welded portion or the dissimilar material joined body.

  In addition, when aluminum alloy powder is mixed and added to this flux, spattering during welding is reduced, and excessive wetness of the molten metal may be suppressed. When the amount of flux filling the outer skin is small, the amount of flux is not stable, and the flux filling amount (filling rate, content rate) varies depending on the part of the FCW. On the other hand, in particular, when the flux filling amount is small, mixing the flux and aluminum alloy powder into the outer shell and filling the outer shell eliminates or alleviates this problem, and at the same time, facilitates the manufacture of the FCW itself. Is also preferable.

  By using a mixed flux having such a specific composition, even when a steel plate coated with a relatively thick hot dip galvanizing (including alloying) is used, different materials can be joined to the hollow profile. That is, the material surface with the galvanized steel sheet or the hollow shape can be cleaned, and the wettability of the weld metal is improved. As a result, bead formation is improved. In addition, generation of a brittle Al—Fe based intermetallic compound layer generated in the dissimilar material joint and a brittle Zn—Fe based compound layer derived from galvanization is suppressed. As a result, the bonding strength is improved. Of course, this effect is also exhibited in the dissimilar material joining of the bare steel plate without galvanization and the hollow shape member.

FCW welding conditions:
The FCW is unwound from the spool being wound, and is fed to the welding location through a welding torch by a feeding roll or the like at a predetermined feeding speed. At this time, the shielding gas is supplied into the welding torch.

  Here, in order to suppress the formation of intermetallic compounds generated at the interface between the hollow shape member and the steel plate, as described above, the minimum necessary base material melting is performed without melting an excessive amount of the base steel plate. It is preferable to select the following welding conditions so that a sound joined state can be obtained with a (diluted) amount.

  The welding current is 70A or more, preferably 80A or more, 120A or less, more preferably 110A or less. The larger the current, the more the intermetallic compound at the bonding interface that is generated may adversely affect the bonding strength. Therefore, it is recommended to bond under relatively low current conditions to suppress these intermetallic compounds. Is done.

  The welding voltage is 10V or more, preferably 15V or more, 30V or less, more preferably 20V or less.

  The welding speed may be appropriately determined in accordance with the welding current and the welding voltage as long as the base material Fe and Al are not excessively melted. However, considering the welding efficiency and the like, it is preferably 20 CPM or more, preferably 30 CPM or more, and 100 CPM or less, more preferably 90 CPM or less.

  As the shield gas, a general-purpose gas such as Ar can be used as appropriate, and a general-purpose flow rate can be selected as the gas flow rate, and there is no particular limitation.

steel sheet:
In order to obtain a lightweight high-strength structural member (dissimilar material joined body) such as an automobile member, the steel plate to be joined to the dissimilar material in the present invention has a tensile strength of 400 MPa or higher, preferably 500 MPa or higher. And Low-strength steel and mild steel with a tensile strength of less than 400 MPa are generally low-alloy steels, and the oxide film is made of iron oxide. Therefore, diffusion of Fe and Al is facilitated, and brittle intermetallic compounds are easily formed. Further, the plate thickness for obtaining the required strength is increased, and the weight reduction is sacrificed. The surface of the steel sheet may or may not be subjected to surface treatment such as galvanization except for coating with an insulating film.

Aluminum alloy hollow profile:
The hollow profile 2 is made of the above-described 6000 series, 7000 series, etc. so that a hollow profile having a uniform daily cross-sectional shape provided with the projections 8 can be obtained easily and inexpensively in the longitudinal direction. A high-strength aluminum alloy is manufactured by billet casting, hot extrusion after billet soaking, and tempering treatment (heat treatment) online or offline. Since the strength of the hollow shape member is a reinforcing member, it is desirable that the strength is high as in the case of the steel plate. It does not matter whether the surface of the hollow material to be joined with the different material is subjected to surface treatment except for coating with an insulating film.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples, and the present invention is not limited to the following examples. Of course, it is also possible to implement them, and they are all included in the technical scope of the present invention.

  As shown in FIG. 1 to FIG. 4, with respect to the welding direction in the longitudinal direction of the aluminum alloy hollow shape member 2, the steel plates 10 and 11 are placed on the upper side and the hollow shape member 2 is placed on the lower side. Using the shape, lap fillet welding by FCW welding (MIG welding) was performed.

  The welding location was only one in the back region 4a on the center side of the rear flange 4, and the back regions 4b and 4c where the webs 5 and 6 on both ends of the rear flange 4 intersect were not performed. For example, even if these back regions 4b and 4c, which are relatively easy to weld, have good weldability, it is meaningless if the back region 4a on the center side of the rear flange 4 is poor. .

  At this time, the amount of protrusion (Xmm) from the steel plate welding surface (upper surface) of the convex portion 8 having a trapezoidal cross section on the side of the aluminum alloy hollow shape member and other design conditions are variously changed. The effect on weldability at the time of welding was investigated. The results are shown in Table 1.

As the trapezoidal shape of the convex portion 8, Table 1 shows the width L1 (mm) of the rear end portion of the convex portion 8 in the width direction of the hollow member and the width L2 (mm) of the tip portion of the convex portion 8 in the width direction of the hollow member. ), The longitudinal sectional area S (mm ² ) of the convex portion 8, the protruding amount X (mm) above the steel plate surface level, and the ratio L 1 / tw between L 1 and the width tw of the middle rib 7. The clearance C between the rear flange 4 surface of the aluminum alloy hollow shape member 2 and the lower surfaces of the steel plates 10 and 11 laminated from above is set to 0, and the root of the convex portion 8 and the center side surfaces 10a and 11a of the respective steel plates. The clearance G was set to 0.5 mm.

  The upper steel plates 10 and 11 were cold-rolled steel plates (high tensile, thickness 1.4 mm) subjected to alloying hot dip galvanizing (GA) with a tensile strength of 980 MPa. The aluminum alloy hollow profile 2 having a lower cross-sectional shape was a tempered extruded profile of a 7000 series aluminum alloy having a 0.2% proof stress of 500 MPa class (the thickness of each part is 4.0 mm in common). . The lengths of the front side flange 3 and the rear side flange 4 are both 150 mm, and the lengths of the middle rib 7 intersecting the center of each flange and the two webs 5 and 6 intersecting each flange end are both The rectangular cross section was 65 mm. The length of the aluminum alloy hollow profile 2 (welding line) was 250 mm.

  The flux cored wire (FCW) is a seam-type type 1 in which the Nocolok flux mixed with aluminum alloy powder is filled with 12% by mass with respect to the total mass of FCW and covered with an A4047 aluminum alloy aluminum alloy skin. A small diameter of 2 mmφ was used. The MIG welding conditions were a welding current of 80 to 90 A, a welding voltage of 16 to 18 V, a welding speed of 40 to 70 cpm (cm / min), and a weld line length of 250 mm. The shielding gas was Ar.

  Joint weldability evaluation: The weldability of the joint was determined by visual observation of the bead and a peeling test using chisel. As for the visual inspection of the bead, the pass (合格) indicates that the bead 12 is on both the welded surface of the steel plates 10 and 11 and the welded surface of the back region 4a at the center of the rear side flange 4 of the aluminum alloy hollow profile 2. Thus, it was in a state of being continuously formed well. And by comparison with this, it evaluated in order of (circle), (triangle | delta), and x by especially the magnitude | size of the bead of the welding surface side of a steel plate. Incidentally, “x” indicates that the bead 12 is hardly present on the welding surface side of the steel plates 10 and 11 or is extremely small.

  In the peeling test using chisel, the tip of the bead 12 is placed near the center of the welded portion (bead 12). The peeled state (destructive state) in the direction was investigated. And the thing with no peeling (destruction) at all over the longitudinal direction of the bead 12 is evaluated as a pass (◎), and compared with this, the magnitude of the peeling (destruction) generated in a part of the bead 12 is large. The evaluation was made in the order of ○, Δ, and ×. Incidentally, “x” indicates a case where the bead 12 is largely peeled and the joint can be considered broken. The peel test with this chisel is a measure that the fracture strength of the joint is 250 N / mm or more if ◎, and a measure that the fracture strength of the joint is less than about 100 N / mm if the symbol is x. .

  From Table 1, the protruding amount X (mm) of the convex portion 8 on the aluminum alloy hollow profile 2 side from the steel plate welding surface (upper surface), the width L1 (mm) of the rear end portion of the convex portion 8 and the middle rib 7 The invention example in which the ratio L1 / tw to the width tw of the above is appropriate is excellent in the visual inspection of the beads and the evaluation of the peeling test. However, the comparative examples in which these are inappropriate are inferior in evaluation of the visual observation of the beads and the peeling test even when weaving is performed.

  In Comparative Examples 4 and 5, the L1 / tw is too small. That is, the width L1 of the rear end portion of the convex portion 8 is too small with respect to the width tw of the middle rib 7. From this result, when welding as a flat back surface without providing the convex portion 8 on the back surface of the central portion 4a of the rear surface side flange as in the past, it is more visually observed than the comparative examples 4 and 5. It is confirmed that the peel test is inferior.

  In Comparative Example 7, together with Invention Example 6, the protruding amount X of the convex portion 8 from the steel plate welding surface (upper surface) is relatively large. For this reason, the weldability is relatively inferior compared to other invention examples in which the protrusion amount X is appropriate. In Comparative Examples 7 and 11, the cross-sectional area S is too large, which is the main cause of poor weldability. Of these, Comparative Example 11 is weaving because L1 is as large as 8 mm, but the cross-sectional area S is too large as compared with Invention Examples 9 and 10 which are also large and corresponding to weaving. The weldability is inferior.

  According to the present invention, even when a steel plate is welded to the rear surface of the rear surface side flange of the aluminum alloy hollow profile, a method for producing a composite reinforcing member and a composite reinforcing member that can obtain high joint strength required as the bending strength member Can provide. Moreover, the construction method is also easy, and a joining method utilizing arc welding capable of efficiently performing wire welding can be provided. Therefore, it is useful in the field of dissimilar material joining between a steel plate and an aluminum alloy hollow member, such as production of a reinforcing member for an automobile body.

1: Composite reinforcing member, 2: Aluminum alloy hollow profile (aluminum alloy extruded profile), 3: Front flange (front wall), 4: Rear flange (rear wall), 5, 6: Web, 7: Medium Rib, 8: convex portion (convex region), 9: rear flange rear surface, 10, 11: steel plate, 12, 13, 14: weld bead

Claims (3)

Laminated steel sheets with aluminum ribs in the shape of a rectangular cross section and laminated on the back side of the rear flange on the tension side when a bending load is applied. The alloy hollow profile is formed at three locations, that is, both ends of the rear flange and the central portion where the middle rib of the rear flange intersects in the longitudinal direction of the aluminum alloy hollow profile. When the aluminum alloy filler metal is integrally joined by lap fillet arc welding, the central region side rear region where the middle rib of the rear side flange of the aluminum alloy hollow profile intersects the aluminum alloy It was formed in advance in the longitudinal direction of the alloy hollow profile, and the two steel plates were laminated so as to sandwich the back region formed in this convex shape, and this convex shape was formed. Back The region satisfies the following conditions so as to protrude between these steel plates, and in this state, the rear surface region formed in a convex shape of the rear surface side flange, and the center of each of the two steel plates facing the back surface region Combined with the side portion on the portion side, as a welded portion on the central portion side where the middle rib of the rear surface side flange intersects, the side surface of the steel plate and the side surface thereof along the longitudinal direction of the aluminum alloy hollow profile A method for manufacturing a composite reinforcing member, wherein welding is integrally performed on a subsequent surface .
Here, the conditions that the convexly formed back region satisfies are that the maximum thickness of the aluminum alloy hollow profile is 8 mm or less, and the plate thickness of the steel sheet is in the range of 0.3 to 4.0 mm. when, before Symbol rear region formed in a convex shape, the area S of the longitudinal section in the upper side region than the upper surface level of the steel sheet by 10 mm ² or less, the back and flush the root portion of the rear surface side flange The width L1 of the rear end portion, which is the length in the width direction of the hollow shape member, is 8 mm or less, and the ratio L1 / tw between the L1 and the width tw of the middle rib is 0.6 or more and 1.2 or less ( However, the width tw of the middle rib is 8 mm or less).   The method of manufacturing a composite reinforcing member according to claim 1, wherein the arc welding is MIG welding or laser welding using a flux cored wire formed by filling a flux inside an aluminum material outer shell. A composite reinforcing member manufactured by the method according to claim 1 or 2, which is on the tension side when a bending load is applied to an aluminum alloy hollow shape member having a daily cross-sectional shape provided with an intermediate rib in a rectangular cross-section. A steel plate is laminated on the back surface of the rear surface side flange, and the laminated steel plate and the aluminum alloy hollow profile are in the center where both end portions of the rear surface side flange intersect the middle rib of the rear surface side flange. Are joined together using an aluminum alloy filler material by lap fillet arc welding in the longitudinal direction of the aluminum alloy hollow shape member at three locations on the part side. A convex back surface region formed in advance in the longitudinal direction of the aluminum alloy hollow profile is formed on the back surface region on the center side where the middle ribs of the rear surface side flange intersect. Provided so as to protrude between the two steel plates laminated so as to sandwich the back region, in this state, each of the convex back region and the two steel plates facing the back region Combined with the side surface portion on the center portion side, as a welding portion on the center portion side where the middle rib of the rear surface side flange intersects with the aluminum alloy hollow profile in the longitudinal direction of the aluminum alloy hollow profile , the steel plate A composite reinforcing member , wherein the bead is covered and integrally joined to the side surface and the subsequent surface .

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