JP2019150839A - Dissimilar material bonding method, bonding auxiliary member and dissimilar material bonded joint - Google Patents

Abstract

To provide a dissimilar bonding method, a bonding auxiliary member and a dissimilar material bonded joint which can bond a plate made of aluminum or aluminum alloy and a plate of material different from the plate by using an inexpensive rotary tool in rigid and high-reliability quality and can be applied either to an open cross-section structure or to a close cross-section structure without restriction.SOLUTION: A dissimilar material bonded joint 1 is the dissimilar material bonded joint provided with an upper plate 10, a lower plate 20 made of aluminum or aluminum alloy which is different from raw material of the upper plate. Therein, the upper plate has a hole 11 and further is provided with a bonding auxiliary member 30 made of aluminum alloy having a stepped shape which has a large diameter part 31 having an outer diameter Plarger than a hole diameter Bof the hole 11 and a small diameter part 32 having an outer diameter Pof the hole diameter Bor less, the small diameter part 32 of the bonding auxiliary member is inserted into the hole provided on the upper plate, a weld metal layer W according to friction binding is formed on a contact part between the lower plate and the small diameter part of the bonding auxiliary member, and the upper plate is held between the large diameter part of the bonding auxiliary member and the lower plate.SELECTED DRAWING: Figure 1B

Description

  The present invention relates to a dissimilar material joining method, a joining auxiliary member, and a dissimilar material joint.

For transportation equipment such as automobiles, the purpose is (a) consumption of petroleum fuel, which is a finite resource, (b) CO ₂ , which is a global warming gas generated by combustion, and (c) travel costs. As a result, improvement in driving fuel consumption is always required. In addition to improving power system technology such as the use of electric drive, reducing the weight of the vehicle body is one of the measures. For weight reduction, there is a means of replacing steel, which is currently the main material, with aluminum alloy, magnesium alloy, carbon fiber reinforced resin (CFRP), etc., which are lightweight materials. However, there are issues such as high costs and insufficient strength to replace everything with these lightweight materials. As a solution, a so-called multi-material design method that combines steel and lightweight materials in the right place is drawing attention. Have been bathed.

  In order to combine steel and the above lightweight materials, there are inevitably places where they are joined. It is known that welding, which is easy with steels, aluminum alloys, and magnesium alloys, is extremely difficult with different materials. The reason for this is that an intermetallic compound (IMC), which is extremely brittle, is formed in the melt-mixed portion of steel and aluminum or magnesium, and the melt-mixed portion is easily broken by an external stress such as tension or impact. . For this reason, welding methods such as resistance spot welding and arc welding cannot be adopted for dissimilar material joining, and other joining methods are generally used.

  As an example of the conventional dissimilar material joining technique, there is a means in which through holes are provided in both a steel material and a lightweight material and restrained from above and below with bolts and nuts. As another example, a means is known in which a caulking member is inserted from one side under a strong pressure and restrained by a caulking effect (see, for example, Patent Document 1).

  Furthermore, as another example, means for directly joining aluminum alloy and steel materials using a friction stir welding tool has been developed (see, for example, Patent Document 2).

  As another example, a means has been devised in which a holed steel and a non-drilled aluminum plate are overlapped and MIG arc welding using an aluminum alloy welding wire is used to close the hole to form a dissimilar joint joint. Yes. (For example, see Patent Documents 3 to 5).

JP 2002-174219 A Japanese Patent No. 5044128 Japanese Patent No. 4438691 Japanese Patent No. 4933923 JP 2006-150439 A

  However, the joining method using bolts and nuts can be used when a steel material and a lightweight material form a closed section structure, or when one of a steel material and a lightweight material forms a closed section structure (see FIG. 29). May not be applicable. Further, even in the case of a joint having an applicable open cross-sectional structure, there is an inconvenience that the positions of the holes in each plate must be accurately aligned.

  Moreover, although the joining method described in Patent Document 1 is a relatively easy method, there is a problem that it cannot be inserted when the strength of the steel is high, and the joining strength depends on the frictional force and the rigidity of the caulking member. Therefore, there is a problem that high joint strength cannot be obtained. In addition, there is a problem that it cannot be applied to a closed cross-sectional structure because it is necessary to press down from both the front and back sides with a jig when inserting.

  Furthermore, the joining method described in Patent Document 2 prevents the formation of intermetallic compounds by applying pressure to the steel material surface while causing the aluminum alloy material to plastically flow in a low temperature region, so that both materials do not melt together. However, there is also a research result that steel and carbon fiber reinforced resin can be joined. However, this joining method cannot be applied to a closed cross-sectional structure, and requires a high pressure, so that there is a problem that it is mechanically large and expensive. Also, the bonding force is not so high.

  The joining methods described in Patent Documents 3 to 5 have a problem that the MIG weld metal of aluminum alloy has low strength due to the amount of heat input and the restriction of the component composition. In addition, since the heat effect extends to the surrounding base material and is softened, high joint strength cannot be obtained.

  Therefore, the existing dissimilar material joining technique has one or more problems such as (i) the member or groove shape is limited to an open cross-sectional structure, and (ii) the joint strength is low. For this reason, in order to spread multi-material design combining various materials, (i ′) applicable to both open and closed section structures, (ii ′) sufficiently high joint strength and reliability New technology that combines the elements of high cost is required.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to make a plate material made of aluminum or an aluminum alloy and a plate material different from the plate material strong and reliable by using an inexpensive rotary tool. It is an object of the present invention to provide a dissimilar material joining method, a joining auxiliary member, and a dissimilar material joint that can be joined with high quality and can be applied to an open sectional structure and a closed sectional structure without limitation.

Here, in order to achieve dissimilar material joining of a plate material made of aluminum or aluminum alloy and a plate material different from the plate material, (A) prevent both members from melting together, (B) do not soften the base material Therefore, it is necessary to satisfy the four requirements of making the heat input as small as possible, (C) making the stress concentration portion a high-strength material, and (D) making it difficult to break geometrically.
Therefore, the present inventor has devised the following means that satisfies all the requirements (A) to (D).

Therefore, the above object of the present invention is achieved by the following configuration.
(1) A dissimilar material joining method for joining a first plate and a second plate made of aluminum or an aluminum alloy different from the material of the first plate,
Drilling a hole in the first plate;
Superimposing the first plate and the second plate;
The small diameter portion of the joining auxiliary member made of aluminum alloy having a stepped shape having a large diameter portion having an outer diameter larger than the hole diameter of the hole and a small diameter portion having an outer diameter equal to or smaller than the hole diameter, Inserting into the hole provided in the first plate;
The joining auxiliary member is rotated while pressure is applied to the surface of the second plate, the contact portion between the second plate and the small diameter portion of the joining auxiliary member is melted and solidified by frictional heat, and is friction-joined. Sandwiching the first plate between the large-diameter portion of the auxiliary joining member and the second plate;
Dissimilar material joining method.
(2) The dissimilar material joining method according to (1), wherein a material of the joining auxiliary member is any one of duralumin, super duralumin, and super super duralumin.
(3) The large-diameter portion of the joining auxiliary member has a tool engaging portion that can be engaged with the tool so that a rotational driving force from a tool for rotating the joining auxiliary member is transmitted. The dissimilar material joining method according to (1) or (2).
(4) A step of applying an adhesive over the entire circumference of the at least one overlapping surface of the first plate and the second plate before the overlapping step. The dissimilar material joining method according to any one of (1) to (3).
(5) In the insertion step, an adhesive is applied to at least one facing surface between the large diameter portion of the joining auxiliary member and the first plate facing the large diameter portion. (1) -Dissimilar material joining method in any one of (4).
(6) The adhesive according to any one of (1) to (5), wherein an adhesive is applied to a boundary portion between the large-diameter portion of the joining auxiliary member and the surface of the first plate after the friction joining step. Dissimilar material joining method.
(7) The dissimilar material joining method according to any one of (1) to (6), wherein natural aging is performed for 30 days or more after the friction joining step.
(8) The dissimilar material joining method according to any one of (1) to (7), wherein the first plate is made of steel, resin, carbon fiber reinforced resin, or non-ferrous metal.
(9) Used in the dissimilar material joining method according to any one of (1) to (8),
A joining auxiliary member made of an aluminum alloy and having a stepped shape having a large diameter portion having an outer diameter larger than the hole diameter of the hole and a small diameter portion having an outer diameter equal to or smaller than the hole diameter.
(10) A dissimilar joint joint comprising a first plate and a second plate made of aluminum or aluminum alloy that is joined to the first plate and is different from the material of the first plate,
The first plate has a hole;
A further comprising a joining auxiliary member made of aluminum alloy having a stepped shape having a large diameter portion having an outer diameter larger than the hole diameter of the hole and a small diameter portion having an outer diameter equal to or smaller than the hole diameter;
The small diameter portion of the joining auxiliary member is inserted into a hole provided in the first plate,
A dissimilar material joint in which a contact portion between the second plate and the small-diameter portion of the joining auxiliary member is friction-joined, and the first plate is sandwiched between the large-diameter portion of the joining auxiliary member and the second plate. Fittings.
(11) The dissimilar joint joint according to (10), wherein a material of the joining auxiliary member is any one of duralumin, super duralumin, and super super duralumin.
(12) The large-diameter portion of the joining auxiliary member is formed with a tool engaging portion that can be engaged with a tool for rotating the joining auxiliary member so as to transmit a driving force for the rotation. The dissimilar joint joint according to (10) or (11).
(13) The overlapping surface of at least one of the first plate and the second plate is provided with an adhesive provided over the entire circumference around the hole. ) The dissimilar joint joint according to any one of the above.
(14) (10) to (13) including an adhesive provided on at least one facing surface between the large diameter portion of the joining auxiliary member and the first plate facing the large diameter portion. The dissimilar material joint according to any one of the above.
(15) The dissimilar joint joint according to any one of (10) to (14), comprising an adhesive provided at a boundary portion between the large-diameter portion of the joining auxiliary member and the surface of the first plate.
(16) The dissimilar joint joint according to any one of (10) to (15), wherein the first plate is made of steel, resin, carbon fiber reinforced resin, or non-ferrous metal.

  According to the present invention, a plate material made of aluminum or an aluminum alloy and a plate material made of a material different from the plate material can be joined with a strong and reliable quality using an inexpensive rotary tool, and an open cross-sectional structure is also achieved. It can be applied to closed cross-section structures without any restrictions.

It is a perspective view of a dissimilar material joint according to an embodiment of the present invention. FIG. 1B is a cross-sectional view of the dissimilar joint joint taken along line II of FIG. 1A. It is the top view and side view of the joining auxiliary member of this embodiment. It is a perspective view of the joining auxiliary member of this embodiment. It is a figure which shows the drilling operation | work of the different material joining method of this embodiment. It is a figure which shows the superimposition operation | work of the different material joining method of this embodiment. It is a figure which shows the friction joining operation | work of the different material joining method of this embodiment. It is a perspective view of the dissimilar material welding joint as a comparative example which piled up and welded the steel upper board and the aluminum lower board. It is sectional drawing of the dissimilar material welded joint of FIG. 4A. FIG. 4B is a cross-sectional view showing a state in which shear tension is applied to the dissimilar material welded joint in FIG. 4A. It is a perspective view which shows the dissimilar material welded joint of FIG. 5A. It is sectional drawing which shows the state which the up-and-down peeling tension acted on the dissimilar material welded joint of FIG. 4A. It is a perspective view which shows the dissimilar material welded joint of FIG. 6A. It is a perspective view of the dissimilar material welding joint as a comparative example which piled up and welded the aluminum upper board and steel lower board which have a hole. It is a perspective view of a dissimilar material welded joint as a comparative example in which a steel upper plate and an aluminum lower plate are overlapped and resistance spot welded. It is sectional drawing of the dissimilar material welded joint of FIG. 8A. It is sectional drawing which shows the state which shear tension acted on the dissimilar material welded joint of FIG. 8A. It is a perspective view which shows the dissimilar material welded joint of FIG. 9A. It is sectional drawing which shows the state which the up-and-down peeling tension acted on the dissimilar material welded joint of FIG. 8A. It is a perspective view which shows the dissimilar material welded joint of FIG. 10A. It is a graph which shows the change of the Vickers hardness at the time of natural aging of a weld metal. It is a perspective view which shows the state which the up-and-down peeling tension acted on the dissimilar material welded joint of this embodiment. It is a perspective view which shows the state which the upper and lower peeling tension acted on the dissimilar material welded joint of this embodiment, and fractured | ruptured. It is a perspective view which shows the state which shear tension acted on the dissimilar material welded joint of this embodiment, and fractured | ruptured. It is a front view of the 1st modification of a joining auxiliary member. It is a front view of the 2nd modification of a joining auxiliary member. It is a front view of the 3rd modification of a joining auxiliary member. It is a front view of the 4th modification of a joining auxiliary member. It is a front view of the 5th modification of a joining auxiliary member. It is the front view and side view of a 6th modification of a joining auxiliary member. It is a perspective view of the 6th modification of a joining auxiliary member. It is the front view and side view of a 7th modification of a joining auxiliary member. It is a perspective view of the 7th modification of a joining auxiliary member. It is the front view and side view of an 8th modification of a joining auxiliary member. It is a perspective view of the 8th modification of a joining auxiliary member. It is a perspective view of the rotary tool applied to the joining auxiliary member of the 8th modification. It is a perspective view of the 9th modification of a joining auxiliary member. It is a perspective view of the rotary tool applied to the joining auxiliary member of the 9th modification. It is sectional drawing of the 10th modification of a joining auxiliary member. It is sectional drawing of the 11th modification of a joining auxiliary member. It is sectional drawing for demonstrating the dimensional relationship of an upper board, a lower board, and a joining auxiliary member. It is sectional drawing of the dissimilar material joint which shows the case where a shear tension acts, when there exists a clearance gap between the hole of an upper board, and the small diameter part of a joining auxiliary member. It is a perspective view of the upper board and lower board for demonstrating the 1st modification of a different material joining method. It is sectional drawing of the dissimilar material joining joint for demonstrating the 1st modification of a dissimilar material joining method. It is a perspective view of the upper board and lower board for demonstrating the 2nd modification of a different material joining method. It is sectional drawing of the dissimilar material joining joint for demonstrating the 2nd modification of a dissimilar material joining method. It is a perspective view of the upper board, lower board, and joining auxiliary member for demonstrating the 3rd modification of a different material joining method. It is sectional drawing of the dissimilar material joining joint for demonstrating the 3rd modification of a dissimilar material joining method. It is a perspective view of the dissimilar material welding joint for demonstrating the 4th modification of a dissimilar material joining method. It is sectional drawing of the dissimilar material welded joint for demonstrating the 4th modification of a dissimilar material joining method. It is the top view, side view, and bottom view which show the joining auxiliary member of this embodiment. It is the top view, side view, and bottom view which show the 12th modification of a joining auxiliary member. It is the top view, side view, and bottom view which show the 13th modification of a joining auxiliary member. It is sectional drawing which shows the state in which friction welding is performed using a joining tool. It is a perspective view which shows the dissimilar material joint with a closed cross-section structure. It is sectional drawing which shows the state in which friction welding is performed using another joining tool.

  Hereinafter, a dissimilar material joining method, a joining auxiliary member, and a dissimilar material joint according to an embodiment of the present invention will be described in detail with reference to the drawings.

  In the dissimilar material joining method of this embodiment, a steel upper plate 10 (first plate) and an aluminum or aluminum alloy lower plate 20 (second plate), which are superposed on each other, are made of aluminum alloy. The dissimilar material joint 1 as shown in FIG. 1A and FIG. 1B is obtained by joining by the friction joining method via the joining auxiliary member 30.

  The upper plate 10 is provided with a hole 11 that penetrates in the thickness direction and faces the overlapping surface of the lower plate 20, and the joining auxiliary member 30 is inserted into the hole 11.

Figure 2A, as shown in FIG. 2B and FIG. 20, the auxiliary bonding member 30 includes a large diameter portion 31 having a larger outer diameter _{P D2} than diameter _{B D} of the hole 11 of the upper plate 10, diameter _{B D} or less It has a stepped shape having a small diameter portion 32 having an outer diameter _PD1 . The large diameter portion 31 is disposed on the upper surface of the upper plate 10, and the small diameter portion 32 is inserted into the hole 11 of the upper plate 10. Further, the upper surface of the large-diameter portion 31 can be engaged with a tool so that a rotational driving force is transmitted from a tool (not shown) for rotating the joining auxiliary member 30 for friction joining described later. A tool engaging portion 33 is provided.

  The material of the joining auxiliary member 30 will be described in detail below. In terms of JIS symbols, aluminum of 2000 series, 3000 series, 4000 series, 5000 series, 6000 series, 7000 series, 8000 series aluminum Alloys are applied, and among these, high strength aluminum alloys duralumin, super duralumin, and super super duralumin are desirable.

  The lower plate 20 and the small diameter portion 32 of the joining auxiliary member 30 are joined by a weld metal layer W having sufficient strength, which is formed by friction joining. As a result, the upper plate 10 is sandwiched between the large-diameter portion 31 of the auxiliary joining member 30 and the lower plate 20.

Hereinafter, the dissimilar material joining method which comprises the dissimilar material joint 1 is demonstrated with reference to FIG. 3A-FIG. 3C.
First, as shown in FIG. 3A, a hole making operation for making a hole 11 in the upper plate 10 is performed (step S1). Next, as shown in FIG. 3B, a superposition operation for superposing the upper plate 10 and the lower plate 20 is performed (step S2). Further, the small diameter portion 32 of the joining auxiliary member 30 is inserted into the hole 11 of the upper plate 10 from the upper surface of the upper plate 10 (step S3). Then, as shown in FIG. 3C, using a tool for rotating the joining auxiliary member 30, the joining auxiliary member 30 is rotated at a high speed while applying pressure to the surface of the lower plate 20, and joined to the lower plate 29 by frictional heat. The contact portion with the small diameter portion 32 of the auxiliary member 30 is melted and solidified to be friction bonded (step S4). As a result, the upper plate 19 is sandwiched between the large-diameter portion 31 of the joining auxiliary member 30 and the lower plate 20.

  Therefore, the upper plate 10 made of steel and the lower plate 20 made of aluminum or aluminum alloy can be bonded with a strong and reliable quality using an inexpensive rotary tool. Depending on the thickness, it is possible to provide a bonding method applicable to a closed cross section.

Here, conventionally, when trying to join metals, the most typical means is arc welding or resistance spot welding.
For example, as shown in FIGS. 4A and 4B, a steel upper plate 10 and an aluminum lower plate 20 are simply overlapped, and arc welding using a steel welding wire is held at a fixed point for a certain time from the upper plate side. When arc spot welding is performed, the lower layer of the weld metal 40a to be formed is an alloy of aluminum and steel. This alloy exhibits an intermetallic compound (IMC) that is brittle because of its high aluminum content. Even if such a dissimilar joint 100a appears to be joined at first glance, if a tensile stress is applied in the lateral direction (shear tension), the weld metal 40a is easily broken as shown in FIGS. 5A and 5B. And it will come off. Further, even when tensile stress is applied in the vertical direction (peeling tension), as shown in FIGS. 6A and 6B, the weld metal 40a breaks or the boundary between the weld metal 40a and the lower plate 20 breaks, and As the plate 10 comes off, the joining is released.
Further, as shown in FIG. 7, even if the upper plate 10 is perforated, the aluminum lower plate 20 is still melted, so that it is not an improvement measure for these easy breaking phenomena.

  Therefore, in FIG. 7, when an aluminum alloy welding wire is used instead of a steel welding wire, the melting point of the aluminum alloy is much lower than that of steel, so that the upper plate 10 made of steel is hardly melted, that is, a metal. It is possible to avoid the formation of intercalation compounds and form a joint. This method is a basic idea of the techniques described in Patent Documents 3 to 5 described above. However, only JIS 1000 series, 4000 series and 5000 series options are specified and sold for aluminum alloy MIG welding materials, and the highest strength 5000 series welding wires such as 5356 and 5183 are used. However, only a tensile strength of at most about 250 MPa can be obtained. Since these weld metals do not have age-hardening properties, the strength does not change even after days. Furthermore, since MIG welding has a high heat input, there is a disadvantage that the aluminum base material is softened under the influence of heat and the strength around the welded portion is also low.

  Further, as shown in FIGS. 8A and 8B, the resistance spot welding method does not use a welding material, but uses a copper electrode 50 to apply a large current to the plates 10 and 20 in close contact with each other while applying pressure. The interface is melted by the resistance heat generation (joule heat generation) to form a weld metal. However, when steel and an aluminum alloy are joined by the resistance spot welding method, generally, the weld metal becomes a mixed intermetallic compound and is extremely brittle, so that only a very low strength can be obtained in both shear tension and peel tension (FIGS. 9A to 9A). (See FIG. 10B). A method of joining steel and aluminum alloy by resistance spot welding has been studied so that welding conditions such as current are adjusted so that they do not melt as much as possible, but the range of effective welding conditions is extremely narrow and it can be joined well. Even so, the joint strength is low. Furthermore, the resistance spot welding method requires a mechanism for pressing the electrodes 50 so as to sandwich the two plates 10 and 20, and is not applicable to a closed cross-sectional structure in which the electrodes do not enter.

  As described above, in arc welding and resistance welding, which are the most typical welding means, it is difficult to join different materials of steel and aluminum alloy easily and with high strength. To reorganize, to achieve dissimilar joining of steel and aluminum alloy, [A] prevent both metals from melting together, [B] minimize heat input to avoid softening the base metal, [C]. It is necessary to devise a shape that makes the stress concentration portion a high-strength material and [D] geometrically difficult to break.

  On the other hand, in the dissimilar material joining method of the present embodiment described above, first, a hole is made in the steel upper plate 10 in advance, and the hole 11 is excellent in affinity with aluminum or aluminum alloy as the lower plate 20. Since the joining auxiliary member 30 made of aluminum alloy is inserted, only the lower plate 20 and the joining auxiliary member 30 are melted together, and the steel upper plate 10 has a mechanism that does not melt at all. Thereby, the said requirement [A] is achieved.

  Further, the dissimilar material joining method of the present embodiment minimizes heat input because it uses frictional heat generated at the interface due to friction rather than arc or heat generation with high heat. Thereby, the thermal influence on the aluminum alloy base material can be extremely suppressed, and the above requirement [B] is achieved.

Further, in the dissimilar material joining method of the present embodiment, since the joining auxiliary member 30 becomes a macroscopic stress concentration portion in both shear tension and peeling tension, it is necessary to increase the strength of the joining auxiliary member 30. In addition, due to the restriction of the requirement [A], the joining auxiliary member 30 must be an aluminum alloy that is not an aluminum containing almost no alloy component but an aluminum alloy that is increased in strength by adding an appropriate amount of other elements. In terms of JIS symbols, aluminum alloys include 2000 series, 3000 series, 4000 series, 5000 series, 6000 series, 7000 series, and 8000 series. Among these, high strength aluminum alloys such as duralumin, super duralumin, and ultra super duralumin are preferable. These alloys are well known as alloys obtained by adding a suitable amount of copper (Cu) and the like, and precipitation hardening by quenching after heating and aging. Specific JIS numbers and components are as follows.
Duralumin (JIS A2017): 4% Cu + 0.5% Mg + 0.5% Mn + residual Al
・ Super duralumin (JIS A2024): 4.5% Cu + 1.5% Mg + remaining Al
・ Ultra-super duralumin (JIS A7075): 5.5% Zn + 2.5% Mg + 1.6% Cu + residual Al

  These alloys have a tensile strength of A2017 and A2024 of 400 MPa or higher, and A7075 of 500 MPa or higher, which is equivalent to that of general steel. In general, duralumin alloys are considered to have poor weldability, but in this embodiment in which friction welding is performed with extremely low heat input, defects such as weld cracks are not generated, and joining is possible. By using the joining auxiliary member 30 processed using these alloys as raw materials, joint strength can be improved.

  In addition, although it is low heat input, the thin weld metal layer W is formed in the contact part of the joining auxiliary member 30 and the lower board 20. In this part, the tissue changes and softens. However, since the width is narrow, even when stress is applied as a joint, a restraining effect from the surroundings works, and a large force is required to break the weld metal layer W. Further, an alloy such as Cu or Mg flows into the weld metal layer W from the material of the joining auxiliary member 30, and by natural aging, the strength is gradually recovered after welding and hardened to the same level as the base material. The number of days required for the hardness to increase due to natural aging is approximately one month, as shown in FIG. Therefore, it is desirable to let one month or more pass before the structure to which the dissimilar material joining method is applied is used. From the above, this embodiment achieves the above requirement [C].

  Furthermore, as for the geometrical shape, the plates 10 and 20 are metal-bonded if they are constrained by sandwiching the plates 10 and 20 from both sides with a member having a larger diameter than the penetrating material, such as a bolt / nut or rivet structure. Without being able to move relatively both in the plane direction and the plate thickness direction, it exhibits a strong bonding force. In this embodiment, since the lower plate 20 and the joining auxiliary member 30 are metal-bonded by friction welding, no geometric consideration is necessary, and only the front side of the upper plate 10 is the large-diameter portion 31 of the joining auxiliary member 30. You only have to restrain it.

In other words, the role of the large-diameter portion 31 of the joining auxiliary member 30 that is wider than the hole 11 provided in the steel upper plate 10 is resistance to vertical peeling stress. Therefore, (see FIG. 20) by applying a joining auxiliary member 30 than diameter _{B D} of the hole 11 having a larger diameter portion 31 of larger outer diameter _{P D2,} as shown in FIG. 12 and FIG. 13A, made of steel It is possible to prevent a phenomenon in which the interface between the upper plate 10 and the joining auxiliary member 30 is peeled off. Note that, as shown in FIG. 13B, since the joint portion has a strong bonding force even with respect to the tensile stress in the shear direction, the base material first exhibits bending deformation without brittle fracture, and up and down. A stress acting state similar to peeling tension is obtained. That is, after sufficient deformation, ductile fracture with high strength. Therefore, this embodiment achieves the above requirement [D].

In addition, as for the shape of the joining auxiliary member 30, the relationship between the large diameter portion 31 protruding from the surface of the upper plate 10 after joining and the small diameter portion 32 inserted into the hole 11 of the upper plate 10 is actually satisfied. If so, the degree of freedom is high. The small-diameter portion 32 is preferably a perfect circle in order to minimize the gap between the small diameter portion 32 and the hole 11 while rotating within the hole 11 of the upper plate 10. On the other hand, the large-diameter portion 31 can have an arbitrary shape as long as it closes the hole 11 provided in the upper plate 10 in terms of its function. The outer shape of the large-diameter portion 31 is not limited to the perfect circle shown in FIG. 2A, and may be, for example, a polygon more than a quadrangle as shown in FIGS. 14A to 14D, or an elliptical shape as shown in FIG. 14E. But you can. Further, as shown in FIG. 14B, the corners of the polygon may be rounded.
In these auxiliary bonding member 30, the outer diameter P _D2 of the large diameter portion 31 is the shortest diagonal distance, defined by the minor axis diameter of the ellipse.

  Further, since the joining auxiliary member 30 needs to be rotated at a high speed while being pressurized in the plate thickness direction, the tool engaging portion 33 for transmitting the rotational driving force of the tool as shown in FIGS. 2A and 2B. Is preferably provided.

  However, the shape of the tool engagement portion 33 is not limited to the plus groove into which the tip of the plus-driver-shaped rotary tool is inserted as shown in FIGS. 2A and 2B. For example, as shown in FIGS. 15A and 15B, if the tip of the rotary tool is a cross male shape, a tool engaging portion 33 having a cross female shape so as to fit is formed on the upper portion of the large diameter portion 31. It is formed. As shown in FIGS. 16A and 16B, if the tip of the rotary tool is a cross-shaped female shape, a tool engaging portion 33 having a cross-shaped male shape is formed on the upper portion of the large-diameter portion 31.

  Further, as shown in FIG. 17C, when the tip of the rotary tool 60 has a prismatic shape with a square cross section, as shown in FIGS. 17A and 17B, as shown in FIGS. A tool engaging portion 33 having a square female shape is formed on the upper portion.

As described above, when the outer shape of the large-diameter portion 31 is a non-circular shape, the outer shape of the large-diameter portion 31 itself may be the tool engagement portion 33 that engages the tip of the rotary tool. For example, as shown in FIG. 18B, when the tip of the rotary tool 60 has a regular hexagonal female shape, as shown in FIG. 18A, a regular hexagon in which the tip of the rotary tool 60 fits the outer shape of the large diameter portion 31. By doing so, it is not necessary to perform groove processing on the upper surface of the large-diameter portion 31.
Note that the tool engaging portion 33 is not shown in some modifications of the joining auxiliary member 30 described below.

  Further, the tip surface of the small diameter portion 32 may have a simple flat shape, but in order to increase the load per unit area and efficiently perform the friction welding, a protrusion 32a is provided at the tip as shown in FIG. 19A. Alternatively, a stepped shape may be used, or a conical tapered surface portion 32b may be provided at the tip as shown in FIG. 19B. In order to increase the frictional resistance, the lower surface of the small-diameter portion 32 may be intentionally rough-finished with a file, or may be finely textured.

Further, as shown in FIG. 20, the height P _H1 of the small diameter portion 32 needs to be changed depending on the thickness B _H of the upper plate 10. If the height P _H1 of the small diameter portion 32 is too small, it will not reach the aluminum alloy of the lower plate 20 and friction welding will be impossible. Conversely, when the height P _H1 of the small-diameter portion 32 is too large, not close contact surface facing the large diameter portion 31 and the upper plate 10, upper plate 10 will move in the vertical direction. Therefore, the height P _H1 of the small diameter portion 32 is desirably the same as or close to the thickness B _H of the upper plate 10. If the height P _H1 of the small diameter portion 32 is slightly larger than the thickness B _H of the upper plate 10, the end face is melted by friction welding, escapes to the gap, and the height P _H1 of the small diameter portion 32 decreases. , Restraint is possible. Specifically, the height P _H1 of the small diameter portion 32 is desirably 125% or less with respect to the plate thickness B _{H of the} upper plate 10. On the other hand, if the height P _H1 of the small-diameter portion 32 is slightly smaller than the thickness B _H of the upper plate 10, the upper plate 10 and the joining auxiliary member 30 are elastically deformed by pressurization, and as a result, the joining auxiliary member If the lower surface of 30 reaches the lower plate 20, joining is possible. Specifically, the height P _H1 of the small diameter portion 32 is desirably 75% or more with respect to the thickness B _H of the upper plate 10.

The outer diameter P _D1 of the small-diameter portion 32 may be equal to or less than diameter B _D of the hole 11 provided in the upper plate 10, but it is desirable to as closely as possible with respect to the bore diameter B _D. The smaller the outer diameter P _D1 of the small diameter portion 32 is, the easier the insertion is with respect to the hole diameter B _{D of the} upper plate 10. On the other hand, a gap generated between the hole 11 provided in the upper plate 10 and the small diameter portion 32 of the joining auxiliary member 30 causes the upper plate 10 and the lower plate 20 to be joined to be displaced from each other. That is, in this dissimilar material joining method, even in the joined state, the force that restrains the upper plate 10 in the horizontal direction is not so strong. Therefore, as shown in FIG. 30 and the gap between the holes 11 of the upper plate 10 slip so as to slide. Therefore, it is desirable that there be as little gap as possible between the small diameter portion 32 of the joining auxiliary member 30 and the hole 11 of the upper plate 10 in the joined state.

  With the above-described configuration, the upper plate 10 can be made of steel, and the lower plate 20 can be made of an aluminum or aluminum alloy material.

  Here, as a problem in the case of directly joining different kinds of metals, another problem is known in addition to the problem of forming the IMC. That is, when dissimilar metals come into contact with each other, it causes corrosion to accelerate in order to form a galvanic cell. Corrosion due to this cause (battery anode reaction) is called electrolytic corrosion. Corrosion proceeds when there is water on the surface where dissimilar metals are in contact with each other, so when this embodiment is applied to a place where water can easily enter as a joint, sealing to prevent ingress of water for the purpose of preventing electrolytic corrosion It is necessary to perform processing. Even in this joining method, a plurality of surfaces where the Al alloy and the steel are in contact are formed, and therefore it is preferable to use a resin-based adhesive not only for the purpose of further improving the joint strength but also as a sealing material.

  For example, as in the first modification shown in FIGS. 22A and 22B, the adhesive 60 may be applied around the joint portion in an annular shape around the joint portion on the joint surface of the upper plate 10 and the lower plate 20. In addition, as a method of applying the adhesive 60 over the entire periphery of the joint portion at the joint surface of the upper plate 10 and the lower plate 20, as in the second modification shown in FIGS. 23A and 23B, In this case, the rate of electrolytic corrosion of the upper plate 10, the lower plate 20, and the weld metal 40 can be reduced.

  24A and 24B, an adhesive 60 may be applied between the periphery of the hole 11 of the upper plate 10 and the lower surface of the large-diameter portion 31 of the joining assisting member 30. . Thereby, the electrolytic corrosion rate of the upper board 10, the joining auxiliary member 30, and the weld metal 40 can be lowered.

  Furthermore, like the 4th modification shown to FIG. 25A and FIG. 25B, by apply | coating the adhesive agent 60 to the boundary part of the large diameter part 31 and the surface of the upper board 10 of the joining auxiliary member 30, the upper board 10 of FIG. The effect of reducing the electrolytic corrosion rate between the base material and the joining auxiliary member 30 is obtained. In the third modification shown in FIGS. 24A and 24B, the application is performed before the friction joining process, and in the fourth modification shown in FIGS. 25A and 25B, the application is executed after the friction joining process.

Furthermore, in the joining auxiliary member 30, the contact surface with the upper plate 10 of the large diameter portion 31 is not necessarily a flat surface as shown in FIG. 26A. That is, the contact surface with the upper plate 10 of the large-diameter portion 31 may be provided with slits 34a and 34b as required, as shown in FIGS. 26B and 26C. In particular, when the circumferential slit 34a or the radial slit 34b is provided on the contact surface side with the upper plate 10, the application of the adhesive 60 enters the gap between the slits 34a and 34b and does not escape, so that stable adhesion is performed. The sealing effect is also ensured. Large-diameter portion defining a height P _H2 in the case of such a non-planar surface is the largest part of the height.

  In addition, for the same purpose, in order to prevent electrolytic corrosion that occurs at the interface between the joining auxiliary member 30 itself and the steel sheet, the surface treatment for forming a film such as an electrical base element, a processed product, an insulating substance, or a passive material is joined to assist. It can also be applied to the member 30. For example, zinc plating, chromium plating, nickel plating, tin (tin) plating, resin coating, ceramic coating, alumite treatment and the like can be mentioned.

  Moreover, although the said embodiment demonstrated the joining of the upper board 10 made from steel, and the lower board 20 made from aluminum or aluminum alloy, in the dissimilar material joining method of this invention, the material of the upper board 10 is limited to steel. However, it may be made of non-ferrous metal such as resin, carbon fiber reinforced resin (CFPR), magnesium alloy or the like. This is applicable because the resin, CFRP, and other various metal plates that are the upper plate 10 are not melted during the bonding.

  As a joining tool used in this embodiment, as shown in FIG. 27, a rotary tool 60 is provided on one side of a C-type or X-type clamp tool 70 which is well known as a resistance spot welding tool. The friction welding tool provided with can be applied. This friction welding tool can be mounted on a robot and moved freely. In order to hold the aluminum alloy joining auxiliary member 30 on the rotary tool 60, a vacuum function is provided in the tool 70, and the pressure between the tool 70 and the joining auxiliary member 30 is lowered and sucked. There are methods such as gripping with air or an electrically driven collet chuck. FIG. 28 shows a dissimilar material joint with a closed cross-section structure joined by the joining tool.

  Further, when the joined body has high rigidity, joining can be performed with the pressing tool 71 from one side. This is because friction welding between aluminum alloys does not require high pressure unlike steel. In the example shown in FIG. 29, a hollow member having a closed cross-sectional structure made of aluminum alloy is applied as a joined body having high rigidity. In this case, one side wall of the hollow member is used as the second plate 20. The first plate 10 made of steel is joined.

As described above, according to the dissimilar material joining method of the present embodiment, the step of forming the hole 11 in the upper plate 10, the step of overlapping the upper plate 10 and the lower plate 20, and the hole diameter _{BD of the} hole 11. A small-diameter portion 32 of a joining auxiliary member 30 made of aluminum alloy having a stepped shape having a large-diameter portion 31 having a large outer diameter P _D2 and a small-diameter portion 32 having an outer diameter P _D1 equal to or smaller than the hole diameter B _D. The step of inserting into the hole 11 provided in the upper plate 10, the joining auxiliary member 30 is rotated while applying pressure to the surface of the lower plate 20, and the lower plate 20 and the small diameter portion 32 of the joining auxiliary member 30 are caused by frictional heat. A step of melting and solidifying the contact portion to frictionally bond the upper plate 10 between the large-diameter portion 31 of the auxiliary joining member 30 and the lower plate 20.
Thereby, the lower plate 20 made of aluminum or aluminum alloy and the upper plate 10 made of a material different from the lower plate 20 can be joined with a strong and reliable quality using an inexpensive rotary tool, and an open cross-sectional structure In addition, it can be applied to a closed cross-sectional structure without any limitation.

  Moreover, since the material of the joining auxiliary member 30 is any one of duralumin, super duralumin, and super super duralumin, it is possible to frictionally join the joining auxiliary member 30 and the lower plate 20, and the strength as the joining auxiliary member 30. Can also be secured.

  Moreover, since the large diameter part 31 of the joining auxiliary member 30 has the tool engaging part 33 that can be engaged with the tool so that the rotational driving force from the tool for rotating the joining auxiliary member 30 is transmitted, The rotational driving force of the tool can be directly transmitted to the joining auxiliary member 30.

  Further, before the overlapping step, a step of applying the adhesive 60 around the hole 11 is further provided on at least one overlapping surface of the upper plate 10 and the lower plate 20. Thereby, an adhesive agent can act as a sealing material besides joint strength improvement, and can reduce the electrolytic corrosion rate of the upper board 10, the lower board 20, and the weld metal 40. FIG.

  Further, in the inserting step, the adhesive 60 is applied to at least one facing surface between the large diameter portion 31 of the joining auxiliary member 30 and the upper plate 10 facing the large diameter portion 31. Thereby, the electrolytic corrosion rate of the upper plate 10, the joining auxiliary member 30, and the weld metal 40 can be lowered.

  Further, after the friction bonding process, the adhesive 60 is applied to a boundary portion between the large diameter portion 31 of the bonding auxiliary member 30 and the surface of the upper plate 10. Thereby, the joining strength of the upper board 10 and the joining auxiliary member 30 can be improved.

  In addition, since the natural aging is performed for 30 days or more after the friction joining process, the hardness of the weld metal layer W in which the joining auxiliary member 30 and the lower plate 20 are friction-joined can be increased.

  Since the upper plate 10 is made of steel, resin, carbon fiber reinforced resin, or non-ferrous metal, it can form dissimilar joints between various materials and aluminum or aluminum alloy.

The joining auxiliary member 30 of this embodiment is made of an aluminum alloy, a large diameter portion 31 having a larger outer diameter _{P D2} than diameter _{B D} of the hole 11, the outer diameter _{P D1} of less diameter _{B D} It has a stepped shape with a small diameter portion 32. Thereby, the joining auxiliary member 30 is suitably used for the above-described dissimilar material joining method.

Further, the dissimilar material joint 1 according to this embodiment is a dissimilar material joint including an upper plate 10 and a lower plate 20 made of aluminum or aluminum alloy different from the material of the upper plate 10 and bonded to the upper plate 10. Te, top plate 10 has a hole 11, a large diameter portion 31 having a larger outer diameter _{P D2} than diameter _{B D} of the hole 10, the small diameter portion 32 having a diameter _{B D} following the outer diameter _{P D1} A joining auxiliary member 30 made of an aluminum alloy having a stepped shape is further provided, and a small diameter portion 32 of the joining auxiliary member 30 is inserted into the hole 11 provided in the upper plate 10, and the lower plate 20 and the joining auxiliary member 30. A weld metal layer W by friction bonding is formed at the contact portion with the small diameter portion 32, and the upper plate 10 is sandwiched between the large diameter portion 31 and the lower plate 20 of the auxiliary joining member 30.
Thus, the dissimilar joint 1 including the lower plate 20 made of aluminum or aluminum alloy and the upper plate 10 made of a material different from the lower plate 20 is strong and reliable using an inexpensive rotary tool. They can be joined and can be applied to both open and closed cross-sectional structures without limitation.

  Note that the present invention is not limited to the above-described embodiments and examples, and modifications, improvements, and the like can be made as appropriate.

DESCRIPTION OF SYMBOLS 10 Upper plate 11 Hole 20 Lower plate 30 Joining auxiliary member 31 Large diameter part 32 Small diameter part 33 Tool engagement part W Weld metal layer

Claims (16)

A dissimilar material joining method for joining a first plate and a second plate made of aluminum or an aluminum alloy different from the material of the first plate,
Drilling a hole in the first plate;
Superimposing the first plate and the second plate;
The small diameter portion of the joining auxiliary member made of aluminum alloy having a stepped shape having a large diameter portion having an outer diameter larger than the hole diameter of the hole and a small diameter portion having an outer diameter equal to or smaller than the hole diameter, Inserting into the hole provided in the first plate;
The joining auxiliary member is rotated while pressure is applied to the surface of the second plate, the contact portion between the second plate and the small diameter portion of the joining auxiliary member is melted and solidified by frictional heat, and is friction-joined. Sandwiching the first plate between the large-diameter portion of the auxiliary joining member and the second plate;
Dissimilar material joining method.   The dissimilar material joining method according to claim 1, wherein a material of the joining auxiliary member is any one of duralumin, super duralumin, and super super duralumin.   The said large diameter part of the said joining auxiliary member has a tool engaging part which can be engaged with the said tool so that the rotational drive force from the tool for rotating the said joining auxiliary member may be transmitted. Or the dissimilar material joining method of 2.   Before the superposition step, the method further comprises a step of applying an adhesive over the entire circumference of the at least one superposition surface of the first plate and the second plate around the hole. The dissimilar material joining method according to any one of claims 1 to 3.   5. The adhesive according to claim 1, wherein, in the inserting step, an adhesive is applied to at least one facing surface between the large-diameter portion of the joining auxiliary member and the first plate facing the large-diameter portion. The dissimilar material joining method according to any one of the above items.   The dissimilar material joining method according to any one of claims 1 to 5, wherein an adhesive is applied to a boundary portion between the large-diameter portion of the joining auxiliary member and the surface of the first plate after the friction joining step. .   The dissimilar material joining method according to any one of claims 1 to 6, wherein after the friction joining step, natural aging is performed for 30 days or more.   The dissimilar material joining method according to any one of claims 1 to 7, wherein the first plate is made of steel, resin, carbon fiber reinforced resin, or non-ferrous metal. It is used for the dissimilar material joining method according to any one of claims 1 to 8,
A joining auxiliary member made of an aluminum alloy and having a stepped shape having a large diameter portion having an outer diameter larger than the hole diameter of the hole and a small diameter portion having an outer diameter equal to or smaller than the hole diameter. A dissimilar joint joint comprising: a first plate; and a second plate made of aluminum or an aluminum alloy different from the material of the first plate and bonded to the first plate,
The first plate has a hole;
A further comprising a joining auxiliary member made of aluminum alloy having a stepped shape having a large diameter portion having an outer diameter larger than the hole diameter of the hole and a small diameter portion having an outer diameter equal to or smaller than the hole diameter;
The small diameter portion of the joining auxiliary member is inserted into a hole provided in the first plate,
In the contact portion between the second plate and the small diameter portion of the joining auxiliary member, a weld metal layer is formed by friction joining,
A dissimilar joint joint in which the first plate is sandwiched between the large-diameter portion of the joining auxiliary member and the second plate.   The dissimilar joint joint according to claim 10, wherein the material of the joining auxiliary member is any one of duralumin, super duralumin, and super duralumin.   The large-diameter portion of the joining auxiliary member is formed with a tool engaging portion that can be engaged with a tool for rotating the joining auxiliary member so as to transmit a driving force for the rotation. The dissimilar material joint according to claim 10 or 11.   At least one of the first plate and the second plate is provided with an adhesive provided over the entire circumference around the hole. The dissimilar material joint according to item.   14. The adhesive according to claim 10, further comprising an adhesive provided on at least one facing surface between the large-diameter portion of the joining auxiliary member and the first plate facing the large-diameter portion. The dissimilar material joint described in 1.   The dissimilar joint joint according to any one of claims 10 to 14, further comprising an adhesive provided at a boundary portion between the large-diameter portion of the joining auxiliary member and the surface of the first plate.   The dissimilar joint joint according to any one of claims 10 to 15, wherein the first plate is made of steel, resin, carbon fiber reinforced resin, or non-ferrous metal.

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