JP5196133B2 - Dissimilar metal plate joining method - Google Patents

Description

  The present invention relates to a method for joining dissimilar metal sheets, and more particularly to a method for spot welding with an adhesive interposed between two metal sheets.

  In the body of an automobile, the weight reduction of the vehicle body is promoted from the viewpoint of improving the fuel efficiency and the operability of the vehicle. As an effective means for reducing the weight, replacement of a steel plate with an aluminum plate can be mentioned. Applications of this aluminum plate have expanded from lids such as trunk lits and doors attached to the vehicle body to parts that affect the rigidity of the vehicle body, such as roof panels.

  On the other hand, high-strength steel plates and ultra-high-tensile steel plates with a tensile strength of 980 MPa or more are adopted as rigid body parts such as pillars and roof rails as countermeasures against collisions and side collisions. As described above, there is a portion where it is difficult to replace the steel plate with the aluminum plate in terms of strength and rigidity, and in such a portion, a structure of a dissimilar metal plate material in which the steel material and the aluminum plate are combined. Steel and aluminum plates differ greatly in physical properties such as melting point, thermal conductivity, resistance, etc., so it is difficult to use the most commonly used electrical resistance spot welding in automobile assembly, especially spot welding equipment between existing steel plates. It is said that. This is because an aluminum plate has a higher electrical conductivity and thermal conductivity than a steel material and requires a large current. Even if the welded portion is formed, since the potential difference is different between the steel material and the aluminum plate, the welded portion constitutes a local battery with an electrolyte such as water, so that there is a problem of so-called galvanic corrosion.

  As a method of electric resistance welding, there is a weld bond method in which spot welding and an adhesive are used in combination. This weld bond method has the advantage that fatigue characteristics, rigidity, etc. are improved and sealing performance is imparted to the periphery of the welded portion to improve the above-mentioned corrosion resistance, as compared with joints by spot welding alone. In JP-A-6-55277, an aluminum alloy-coated steel plate and an aluminum plate are joined together by a weld bond method to form an Al-Fe alloy layer having a sealing property at a joining interface, and a high joining strength. A technique for obtaining the above has been proposed.

JP-A-6-55277

  The joining mechanism between the steel plate and the aluminum plate is that the aluminum plate is melted and scattered because the interface portion of the aluminum plate is melted and the bonding strength is obtained by causing diffusion between Al and Fe. In particular, the amount of scattering tends to increase as the supply current during welding increases. When this scattering occurs, there is a problem that sufficient sealing performance cannot be ensured because the molten aluminum proceeds in a state of crossing the adhesive.

  As shown in FIGS. 17 and 18, an experiment was conducted on the above-described welding by the weld bond method. As shown in FIG. 17, the aluminum alloy plate A and the steel plate B were disposed so as to overlap each other with an adhesive C interposed therebetween. The adhesive C uses a thermosetting resin. Next, as shown in FIG. 18, after positioning with a positioning jig or the like, the joint was pressurized with the electrode D and energized to form a weld.

  FIG. 19 shows a cross-sectional view of the main part of the joint. Since the aluminum alloy plate A and the steel plate B are pressed by the electrode D, the aluminum alloy plate A and the steel plate B are deformed into a concave shape warped from the welded portion, and a gap is formed at the joint interface along with this deformation. Moreover, the adhesive cutting E resulting from scattering was observed in the adhesive C in the right gap.

  FIG. 20 shows a plan view of the welded portion excluding the steel plate B. FIG. More than half of the periphery of the joint portion can secure the adhesion area by the adhesive C, but the remainder has an adhesive cut-out E region due to scattering. It can be seen that part of the dust reaches the outer peripheral edge of the adhesive C. From the above, it is considered that the metal plate material is deformed into a concave shape by the pressure applied by the electrode D, and the scattering and progress of the scattering are increased by the adhesive C escaping into the gap generated at the bonding interface.

  It was also found that when scattering occurs, the tensile shear strength once decreases but then improves. This is because the oxide film on the surface of the aluminum alloy is destroyed by melting, and impurities existing at the interface can be released to the outside, and the diffusion bonding between Al and Fe is presumed to be strengthened. . In other words, in order to obtain a high bonding strength, it is necessary to take measures against adhesive breakage while allowing the occurrence of scattering.

  An object of the present invention is to prevent seal failure due to scattering in a method of spot welding a dissimilar metal plate with an adhesive interposed, while suppressing escape of the adhesive during spot welding.

The dissimilar metal plate material joining method according to claim 1 is characterized in that an adhesive is interposed between the bonded portion of the first metal plate material and the bonded portion of the second metal plate material having a melting point higher than that of the first metal plate material. In a joining method in which electric resistance spot welding is performed in a state in which a joined portion is pressed with a pair of electrodes, an adhesive is interposed between the joined portion of the first metal plate material and the joined portion of the second metal plate material. A first step, a second step of increasing the superposition force around the welding position of the first metal plate material and the second metal plate material, and a pair of the superposition force around the welding position is increased. A third step of welding with an electrode, and provided with a pressurizing means for increasing the overlapping force around the welding position, the pressurizing means being operated using a pressure force of a pair of electrodes, The convex part is made to correspond to the welding position of the joined part of one of the metal plate members. Form, is characterized by an increased superposition force around the welding position by pressurizing said protrusions at one electrode of the pair of electrodes.

Method for joining dissimilar metal sheet according to claim 2 is the invention of claim 1, the first metal plate is an aluminum alloy plate, a second metal plate is steel, characterized by forming a protrusion on the aluminum alloy plate It is said.

Method for joining dissimilar metal sheet according to claim 3 is the invention of claim 1 or 2, characterized in that a first metal plate and the second metal plate is a vehicle body structure plate.

According to the first aspect of the present invention, in the method of spot-welding dissimilar metals with an adhesive interposed therebetween, it is possible to prevent the adhesive from running out due to the occurrence of scattering, and to ensure the joining strength and the sealing performance. That is, by increasing the overlapping force around the welding position, it is possible to prevent the metal plate material from warping due to the pressurization of the electrodes and to suppress the escape of the adhesive. Therefore, it is possible to prevent the scattering from progressing over a wide range to the outer peripheral edge of the adhesive.
Furthermore, it is possible to provide a pressurizing means for increasing the superposition force around the welding position, and to operate the pressurizing means using the pressurizing operation at the time of welding with the electrodes. Therefore, it is possible to effectively increase the overlapping force around the welding position without using a separate driving source that generates the overlapping force. In addition, by changing the shape of the metal plate material, it is possible to increase the overlapping force around the welding position without using a driving source that separately generates the overlapping force and a pressurizing mechanism.

According to the invention of claim 2 , the same effect as that of the invention of claim 1 can be obtained when the first metal plate material is an aluminum alloy plate and the second metal plate material is a steel plate.

According to the invention of claim 3 , the same effect as that of the invention of claim 1 or 2 can be obtained in the structural plate material of the vehicle body.

  Hereinafter, the best mode for carrying out the present invention will be described based on the first embodiment.

  Embodiment 1 of the present invention will be described below with reference to the drawings.

  As shown in FIGS. 1 and 2, the body structure M of a wagon-type automobile includes a pair of left and right front pillars 1, a pair of left and right center pillars 2, a pair of left and right rear pillars 3, and a pair of left and right front pillars 1. A front header 4 that connects the upper ends of the rear pillars, a rear header 5 that connects the upper ends of the pair of left and right rear pillars 3, and a pair of left and right extending across the upper ends of the front pillars 1 and the upper ends of the rear pillars 3. A roof side rail 6 and a roof panel 7 are provided. Various members other than the roof panel 7 are made of steel plates. FIG. 2 is a plan view of the main part of the vehicle body structure M of the automobile shown with the roof panel 7 omitted.

  The roof panel 7 made of a 6000 series aluminum alloy plate has conical convex portions 8 and vertical portions 9 at the left and right end portions at predetermined intervals along the vehicle width direction corresponding to the welding positions at the front and rear, left and right end portions. doing. The front upper end of the vehicle body forms a closed cross-sectional structure with the front end portion of the roof panel 7 and the front header 4, and the rear rear end of the vehicle body forms a closed cross-sectional structure with the rear end portion of the roof panel 7 and the rear header 5. Further, steel reinforcing plate members 10a to 10d are laid across a pair of left and right roof side rails 6 to reinforce the roof strength. The roof side rail 6 at the upper end of the vehicle body has a closed cross section composed of a cab side outer 11 and a roof rail inner 12 on the cabin side, and a roof rail reinforcement 13 is arranged so that the closed cross section is divided into two. It has become. The roof panel 7 is joined to the vehicle body M by electrical resistance spot welding to the front header 4, the rear header 5 and the roof side rail 6.

  The electric resistance spot welding apparatus 14 that performs the spot welding will be described with reference to FIG. The spot welding device 14 includes a robot 16 equipped with a welding gun 15, a control device 17 that controls the driving of the welding gun 15 and the robot 16, and a spot welding with the welding gun 15, and positioning and holding in a state where metal plate materials are overlapped. Positioning jig (not shown). The robot 16 is a general-purpose 6-axis vertical articulated robot, and a welding gun 15 is attached to the tip of the robot hand. The robot 16 moves the welding gun 15 to a welding operation position of a metal component held by a positioning jig and a standby position retracted from the welding operation position.

  The welding gun 15 has a U-shaped frame, and includes a first electrode 20 installed on the electrode support 18, a second electrode 21 installed on the electrode support 19, and a drive mechanism 22. The first electrode 20 and the second electrode 21 are arranged opposite to each other, and the driving mechanism 22 moves the electrode on the axis to control the pressurizing force and the interval between the first electrode 20 and the second electrode 21. . As welding conditions, the energizable current value is set to 8K to 16KA, the applied pressure is set to 300 to 500Kgf, and the energizing time is set to 0.05 to 0.3 seconds.

Below, the spot welding process of the roof panel 7 and the roof side rail 1 is demonstrated.
As shown in FIG. 4, after the vehicle structure M is set on the positioning jig, the one-part thermosetting epoxy adhesive is bonded to the flange portion 4 a located below the front header 4 in the vehicle body so as to cover the welding position. The agent 23 is applied to a plurality of locations at predetermined intervals along the vehicle width direction. The adhesive may be other thermosetting adhesives such as urethane adhesives and acrylic adhesives, as long as electrical insulation can be ensured. The thickness of the adhesive 23 is about 100 μm.
A rubber sealer 24 is intermittently disposed along the vehicle width direction on the flange portion 4b located above the vehicle body of the front header 4. The sealer 24 is based on a mixture of an elastomer such as butyl rubber or polyisobutylene and an adhesive resin.

  As shown in FIG. 5, the roof panel 7 separately set on the positioning jig is positioned with respect to the front header 4. As described above, a plurality of conical convex portions 8 are formed at predetermined intervals along the vehicle width direction at the vehicle body front end portion of the roof panel 7 corresponding to the welding position. As a state before welding, the lower end portion 8 a of the convex portion 8 of the roof panel 7 abuts on the adhesive 23, and the adhesive 23 is partially accommodated in the space formed by the convex portion 8. . The roof panel 7 is a 6000 series aluminum alloy plate having a thickness of 1.2 mm.

  After positioning in the positional relationship, welding is performed by the spot welding device 14. The welding gun 15 is moved so that the electrodes 20 and 21 are moved closer to each other at the position of the convex portion 8, and the convex portion 8 of the roof panel 7 and the flange portion 4 a of the front header 4 are interposed with the adhesive 23. Pressurize and then energize in the pressurized state. As shown in FIG. 6, the convex portion 8 is crushed by the pressure applied by the electrodes 20 and 21, and the roof panel 7 and the front header 4 are completely welded. Next, the rear header 5 and the roof panel 7 are joined in the same manner.

The operation of the first embodiment will be described with reference to FIGS.
As shown in FIG. 7, the convex portion 8 of the roof panel 7 has a conical shape, and the adhesive 23 is applied to a range wider than the lower end portion 8 a. In Example 1, the space formed by the protrusions 8 is partially filled with the adhesive 23.

  As shown in FIG. 8, after the pressing operation of the electrodes 20 and 21, the electrode 20 contacts the apex 8 b of the convex portion 8, and the electrode 21 contacts the flange portion 4 a of the front header 4. When pressurization by the electrodes 20 and 21 further proceeds, the lower end portion 8a of the convex portion 8 presses the adhesive 23, and the lower end portion 8a and the flange portion 4a come into pressure contact to form a closed space in which the adhesive 23 is accommodated. Due to the further pressurization of the electrodes 20 and 21 after the pressure contact, the closed space is crushed in a state where the lower end portion 8a of the convex portion 8 and the flange portion 4a are in pressure contact, and the vertex 8b of the convex portion 8 and the flange portion 4a is energized while being in pressure contact with 4a.

  As shown in FIG. 9, the apex 8b part of the convex part 8 and the flange part 4a form the welding part in the state which sealed the adhesive agent 23 in the closed space formed with the convex part 8 and the flange part 4a. That is, the shape of the convex portion 8 is used to not only suppress the warpage of the metal plate material due to the applied pressure of the electrode, but also actively form a closed space to prevent the adhesive 23 from escaping. Suppressing the adhesive breakage caused by. An Al—Fe alloy layer is formed at the interface between the apex 8b portion of the convex portion 8 and the flange portion 4a.

  Next, a method for joining the roof panel 7 and the roof side rail 6 according to the second embodiment will be described with reference to FIGS. In this joining method, the same members as those in the joining method of the first embodiment are denoted by the same reference numerals and the description thereof is omitted.

As shown in FIG. 10, the flange portions 11a, 12a, 13a and the vehicle body outer flange portions 11b, 12b, 13b of the cab side outer 11, the roof rail inner 12, and the roof rail reinforcement 13 are formed in the vehicle body assembly process. The closed cross section is configured in advance by spot welding or the like. The cab side outer 11 is made of an alloyed hot-dip galvanized mild steel plate having a thickness of 0.8 mm, and the roof rail reinforcement 13 is made of a 980 MPa class high-tensile steel plate having a thickness of 1.4 mm.
After the vehicle structure M including the roof side rail 6 is set on a positioning jig, an epoxy adhesive 6 is applied to the flange portion 11a on the vehicle body inner side of the cab side outer 11 with a thickness of about 100 μm so as to cover the welding position. .

  As shown in FIG. 11, the roof panel 7 separately set on the positioning jig is positioned with respect to the roof side rail 6. As described above, the upright portions 9 are formed at the outer edge portions at the left and right end portions of the roof panel 7 outside the vehicle body, and the convex portions 8 of about 300 μm are provided along the vehicle width direction at the portion corresponding to the adhesive 23. Formed at predetermined intervals. As a state before welding, the lower end portion 8 a of the convex portion 8 of the roof panel 7 abuts on the adhesive 23, and the adhesive 23 is partially accommodated in the space formed by the convex portion 8. .

  After positioning in the positional relationship, welding is performed by the spot welding device 14. The welding gun 15 is moved so that the electrodes 20 and 21 are moved closer to each other at the position of the convex portion 8 so that the flange portions 11a and 12a of the convex portion 8 of the roof panel 7, the cab side outer 11 and the roof rail reinforcement 13 are joined. And with the adhesive 23 interposed, and then energized with 12 KA in the pressurized state. As shown in FIG. 12, the convex portion 8 is crushed by the pressure applied by the electrodes 20 and 21, and the roof panel 5 and the roof side rail 6 are completely welded.

The operation of the second embodiment will be described with reference to FIGS.
Similar to the first embodiment, after the pressing operation of the electrodes 20 and 21, the electrode 20 contacts the apex 8 b of the convex portion 8, and the electrode 21 contacts the flange portion 13 a of the roof rail reinforcement 13. When the pressurization by the electrodes 20 and 21 further proceeds, the lower end portion 8a of the convex portion 8 presses the adhesive 23, and the lower end portion 8a and the flange portion 11a of the cab side outer 11 are in pressure contact with each other to accommodate the adhesive 23 Form. Due to further pressing force of the electrodes 20 and 21 after the pressure contact, the closed space is crushed in a state where the lower end portion 8a of the convex portion 8 and the flange portion 11a are in pressure contact, and the vertex 8b of the convex portion 8 and the flange portion It will be energized in a state where it is in pressure contact with 11a.

As shown in FIG. 15, the apex 8b portion of the convex portion 8 and the flange portion 11a form a welded part in a state where the adhesive 23 is sealed in a closed space formed by the convex portion 8 and the flange portion 11a. The adhesive breakage caused by the occurrence of scattering is suppressed.
Nugget N1 is confirmed between the flange portion 11a of the cab side outer 11 and the flange portion 13a of the roof rail reinforcement 13, and the structure of the weld region of the roof rail reinforcement 13 is coarsened. Moreover, in the junction part of the roof panel 7 and the flange part 11a of the cab side outer 11, a nugget was confirmed in N2 area | region by the side of the roof panel 7, and it was observed that the interface has been diffusion-bonded. In particular, when the plate assembly of the cab side outer 11 and the roof rail reinforcement 13 and the roof panel 7 are welded, the energization resistance can be increased compared to the first embodiment, and the nugget on the roof panel 7 side can be formed in a short time. In addition, high bonding strength can be obtained.

Next, the structure of the electrode according to Example 3 will be described with reference to FIG.
On the outer periphery of the electrodes 20 and 21 of the welding gun 15, annular holding portions 25 and 26 are installed, respectively. The tip portions 25a and 26a of the grip portions 25 and 26 are positioned in front of the tips of the electrodes 20 and 21, and are set so as to come into contact before the electrodes when the electrodes 20 and 21 move in proximity. Further, the connecting members 20 a and 21 a that connect the electrodes 20 and 21 to the electrode support portions 18 and 19 are movable relative to the grip portions 25 and 26.

The welding operation of the grip portions 25 and 26 will be described.
At the time of welding, when the pressurizing operation is started, the electrode support portions 18 and 19 are brought close to the plate member to be welded, and the electrodes 20 and 21 and the gripping portions 25 and 26 are also brought close thereto. As described above, the front end portions 25a and 26a of the gripping portions 25 and 26 are in contact with the plate material to be welded before the electrodes 20 and 21 so that the plate material to be welded is gripped up and down. When the operation further proceeds and the pressing force to be gripped becomes a predetermined value or more, the connecting members 20a and 21a move independently with respect to the gripping portions 25 and 26, and pressurization energization of the welding parts by the electrodes 20 and 21 is performed. The predetermined value is a value that does not cause the adhesive 23 to escape when the electrodes 20 and 21 are pressed.

Next, a modification in which the above embodiment is partially changed will be described.
1) In the first and second embodiments, the example in which the joining method of the present invention is applied to the body structure of a wagon-type automobile has been described. However, the joining method of the present invention is also applied to the body structure of a sedan-type automobile. Can be applied.

2) In the first and second embodiments, the joining technique of the aluminum alloy plate roof panel, the alloyed hot-dip galvanized mild steel plate front header and cab side outer, and the roof rail reinforcement of 980 MPa class high-tensile steel plate will be described as an example. However, the present invention can be applied to a combination of other metal plate materials or a combination of the same metal plate materials. Further, the metal plate materials may be joined by three or more, and in particular, when joining metal plate materials having a low melting point, it is preferable to superimpose and join three or more pieces. Furthermore, the application part is not limited to the part of the embodiment, and the joining method of the present invention can be applied to a part requiring countermeasures against corrosion such as an engine support member in the engine room.

3] In the first and second embodiments, the spot welding current value can be changed according to the number and the material of the metal plates. In particular, if it is in the range of 8K to 16KA, an existing spot welding apparatus for steel sheet can be used, and the two-piece welding of Example 1 requires a high current value in order to increase the joint strength.

4] In the first and second embodiments, the shape of the convex portion is a conical shape. However, any shape may be used as long as it can accommodate an adhesive such as a hemispherical shape and can suppress escape of the adhesive. Moreover, although the convex part formed in the roof panel was 300 micrometers, it can set in the range which can suppress the escape of an adhesive agent and can accommodate an adhesive agent. Moreover, if it is 1 mm or less, it is also possible to absorb the distortion by extension of a roof panel and to improve the rigidity of an edge part.

5] In the third embodiment, the tip of the gripping portion is formed in an annular shape, but the shape of the tip of the gripping portion may be formed in accordance with the welding position structure.

6] In the third embodiment, the grip portion is formed coaxially with the electrode. However, any structure may be used as long as the electrode can be applied with the driving mechanism, and the electrode can be configured separately from the electrode.

7] In addition, those skilled in the art can implement the present invention in various forms with various modifications without departing from the spirit of the present invention, and the present invention includes such modifications. is there.

It is a disassembled perspective view of the vehicle body structure and roof panel of Example 1 of the present invention. It is a principal part top view of the vehicle body structure except a roof panel. It is a side view of an electrical resistance spot welding apparatus. It is sectional drawing of the front header before joining of Example 1 of this invention. It is sectional drawing at the time of joining of a roof panel and a front header. It is sectional drawing after the completion of joining of a roof panel and a front header. It is principal part sectional drawing of the joining initial stage of a roof panel and a front header. It is principal part sectional drawing of the joining latter stage of a roof panel and a front header. It is principal part sectional drawing after the completion of joining of a roof panel and a front header. It is sectional drawing of the roof rail before joining of Example 2 of this invention. It is sectional drawing at the time of joining of a roof panel and a roof rail. It is sectional drawing after the completion of joining of a roof panel and a roof rail. It is principal part sectional drawing of the joining initial stage of a roof panel and a roof rail. It is principal part sectional drawing of the joining latter stage of a roof panel and a roof rail. It is principal part sectional drawing after the completion of joining of a roof panel and a roof rail. It is an expansion perspective view of the electrode periphery of Example 3 of this invention. It is principal part sectional drawing of the joining initial stage in the conventional weld bond method. It is principal part sectional drawing of the joining late stage in the conventional weld bond method. It is principal part sectional drawing after the completion of joining in the conventional weld bond method. It is a top view of the welding part after the completion of joining in the conventional weld bond method.

M Car body structure 4 Front header 4a Flange part 7 Roof panel 8 Convex part 11 Cab side outer 11a Flange part 13 Roof rail reinforcement 13a Flange part 14 Spot welding device 15 Welding gun 20 First electrode 21 Second electrode 23 Adhesive

Claims (3)

An adhesive is interposed between the bonded portion of the first metal plate material and the bonded portion of the second metal plate material having a melting point higher than that of the first metal plate material, and both the bonded portions are pressurized with a pair of electrodes. In the joining method of dissimilar metal plates that are spot-welded with electric resistance in the state,
A first step of interposing an adhesive between the bonded portion of the first metal plate material and the bonded portion of the second metal plate material;
A second step of increasing the overlapping force around the welding position of the first metal plate and the second metal plate;
And a third step of welding a pair of electrodes in a state of enhanced superposition force around the welding position,
A pressurizing means for increasing the superposition force around the welding position is provided in advance, and the pressurizing means is operated using a pressurizing force of a pair of electrodes,
A convex portion is formed in correspondence with the welding position of the joined portion of one of the metal plate members, and the convex portion is pressed with one electrode of the pair of electrodes to form a welding position. A method for joining dissimilar metal sheets characterized by increasing the surrounding superposition force . 2. The method for joining different metal plates according to claim 1, wherein the first metal plate is an aluminum alloy plate and the second metal plate is a steel plate, and a convex portion is formed on the aluminum alloy plate . The method for joining different metal plate materials according to claim 1 or 2, wherein the first metal plate material and the second metal plate material are constituent plate materials of a vehicle body .