Friction stir spot welding method and friction stir spot welding device

Abstract

A friction stir spot welding device (M) performs friction stir welding of an upper plate (31) and a lower plate (32). In a state in which the pin (11) is retracted with respect to the upper plate surface (31A), the controller (C) presses the shoulder (12) from the upper plate surface (31A) to a specified reference position set based on the lower plate surface (32A) with a first pressure, and then presses the shoulder (12) from the reference position to a press-in position deeper than the lower plate surface (32A) with a second pressure. When the hardness of the upper plate (31) is lower than the hardness of the lower plate (32), the first pressure is set to be lower than the second pressure, and when the hardness of the upper plate (31) is higher than the hardness of the lower plate (32), the first pressure is set to be higher than the second pressure.

Description

Friction stirring point connection method and friction stirring point connection device Technical Field

[0001] This disclosure relates to a friction stirring point joining method and a friction stirring point joining device for joining multiple metal components. Background Technology

[0002] As components of structures such as aircraft, railway vehicles, and automobiles, joints are sometimes used, which are formed by joining multiple metal parts. One known method of such joining is the friction stirring point joining method.

[0003] Patent Document 1 discloses a joining method for forming a joint by frictionally stirring and point-joining three metal components using a reciprocating rotary tool. The reciprocating rotary tool has a coaxially arranged stirring pin, an inner shoulder component, and an outer shoulder component. The stirring pin is sometimes referred to as a pin, and the inner shoulder component is sometimes referred to as a shoulder. Furthermore, the outer shoulder component is sometimes referred to as a clamping member. The shoulder has a cylindrical shape that encloses the cylindrical pin, and the clamping member has a cylindrical shape that encloses the shoulder. In this technique, for the overlapping portion of the three metal components to be point-joined, the pin and shoulder are first pressed into the vicinity of the interface between the first and second components with their distal ends flush, and then the pin is further pressed into the vicinity of the interface between the second and third components, protruding relative to the shoulder, thereby forming a stirring joint that points-joins the three metal components in the overlapping portion.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Publication No. 2006-320924

[0007] In conventional friction stirring point joining methods as described in Patent Document 1, when a rotating tool enters a metal component, the metal component sometimes deforms along its planar direction, especially when the point joining position is located near the end of the metal component, there is a problem that the end of the joint body deforms. Summary of the Invention

[0008] The purpose of this disclosure is to provide a friction stirring point joining method and a friction stirring point joining device that can suppress deformation around the point joining position in a joint body.

[0009] One aspect of this disclosure relates to a friction stirring point joining method, which joins a first member and a second member by softening them through frictional heat. The first member and the second member are each formed of metal, the first member having a first surface and a first back surface, and the second member having a second surface and a second back surface. This friction stirring point joining method includes the following steps: preparing a friction stirring point joining device comprising a pin and a shoulder, the shoulder being cylindrical and having a hollow portion for inserting the pin; arranging the first member and the second member in such a way that at least a portion of the second surface faces the first back surface and the first member overlaps with the second member; arranging the pin and the shoulder facing the overlap; and setting a first pressure and a second pressure for pressing into the shoulder in such a way that, when the hardness of the first member is lower than the hardness of the second member... The first pressure is set to be less than the second pressure. If the hardness of the first component is higher than the hardness of the second component, the first pressure is set to be greater than the second pressure. With the pin retracted relative to the overlapping portion, the shoulder is pressed into a designated reference position set with the second surface as a reference using the first pressure. The shoulder is pressed into a pressing position deeper than the second surface using the second pressure. Then, the shoulder is retracted from the pressing position and the pin enters the overlapping portion.

[0010] Furthermore, another aspect of this disclosure relates to a friction stirring point joining device that joins a first member and a second member by softening them through frictional heat. The first member and the second member are each formed of metal, the first member having a first surface and a first back surface, and the second member having a second surface and a second back surface. This friction stirring point joining device includes: a joining tool comprising a pin and a shoulder, the shoulder being cylindrical and having a hollow portion for inserting the pin; a rotating mechanism capable of rotating the joining tool; a moving mechanism capable of independently moving the pin and the shoulder in the direction in which the pin extends; and a control unit controlling the rotating mechanism and the moving mechanism. The control unit sets the first pressure and the second pressure for pressing into the shoulder in the following manner: when the hardness of the first member is lower than the hardness of the second member, the first pressure is set to be less than the second pressure; when the hardness of the first member is higher than the hardness of the second member, the first pressure is set to be greater than the second pressure. The control unit controls the rotation mechanism and the movement mechanism in the following manner: when at least a portion of the second surface is facing the first back surface and the first member is perpendicular to the second back surface... The first and second components are arranged in an overlapping manner with the pin and the shoulder facing each other. The pin is retracted relative to the overlapping portion, and the shoulder is pressed from the first surface side to a designated reference position set with the second surface as a reference with the first pressure. The shoulder is then pressed from the reference position to a pressing position deeper than the second surface with the second pressure. Then, the shoulder is retracted from the pressing position and the pin enters the overlapping portion. Attached Figure Description

[0011] Figure 1 is a schematic diagram showing the configuration of the friction stirring point connection device involved in this disclosure.

[0012] Figure 2 is a diagram showing the shoulder pre-pressing process in which the shoulder is pressed into the overlapping part of the joint in advance when using a friction stirring point joining tool.

[0013] Figure 3 is a flowchart illustrating the process flow of a friction stirring point bonding method according to an embodiment of the present disclosure.

[0014] Figure 4 is a schematic cross-sectional view illustrating the joint of the joint.

[0015] Figure 5A is a diagram illustrating a portion of the shoulder pre-process in a friction stirring point bonding method according to an embodiment of the present disclosure.

[0016] Figure 5B is a diagram illustrating a portion of the shoulder pre-process in a friction stirring point bonding method according to an embodiment of the present disclosure.

[0017] Figure 6 is a diagram illustrating the friction stirring point bonding method, showing the shift in shoulder indentation and plate end deformation.

[0018] Figure 7 is a graph illustrating the relationship between the recess amount and TSS in an embodiment of the friction stirring point bonding method involved in this disclosure.

[0019] Figure 8 is a graph illustrating the relationship between the distance from the end of the plate to the outer periphery of the shoulder and the amount of end deformation, used to illustrate an embodiment of the friction stirring point bonding method involved in this disclosure.

[0020] Figure 9 is a diagram illustrating the relationship between a reference position and the amount of end deformation in an embodiment of the friction stirring point bonding method involved in this disclosure.

[0021] Figure 10 is a graph illustrating the relationship between the pressure ratio P1 / P2 and the amount of end deformation in an embodiment of the friction stirring point bonding method involved in this disclosure.

[0022] Figure 11 is a diagram illustrating the relationship between the plate assembly of the upper and lower plates and the end deformation amount, used to explain an embodiment of the friction stirring point bonding method involved in this disclosure.

[0023] Figure 12A is a perspective view illustrating the types of plate assemblies used to explain an embodiment of the friction stirring point bonding method involved in this disclosure.

[0024] Figure 12B is a perspective view illustrating the types of plate assemblies used to explain an embodiment of the friction stirring point bonding method involved in this disclosure.

[0025] Figure 12C is a perspective view illustrating the type of plate assembly used to explain an embodiment of the friction stirring point bonding method involved in this disclosure.

[0026] Figure 13 is a graph illustrating the relationship between the presence or absence of adhesive application and the amount of recess in an embodiment of the friction stirring point bonding method involved in this disclosure.

[0027] Figure 14 is a graph illustrating the relationship between the presence or absence of adhesive application and TSS in an embodiment of the friction stirring point bonding method involved in this disclosure.

[0028] Figure 15 is a graph illustrating the relationship between the presence or absence of adhesive application and CTS in an embodiment of the friction stirring point bonding method according to this disclosure.

[0029] Figure 16 is a graph illustrating the relationship between the distance from the end of the plate to the outer periphery of the shoulder and the amount of end deformation, used to illustrate an embodiment of the friction stirring point bonding method involved in this disclosure.

[0030] Figure 17A is a schematic diagram of the joint body used to illustrate the friction stirring point joining method according to a modified embodiment of the present disclosure.

[0031] Figure 17B is a schematic diagram of the joint body used to illustrate the friction stirring point joining method according to a modified embodiment of the present disclosure.

[0032] Figure 18 is a perspective view showing the end deformation of the sheet metal in other friction stir bonding methods compared with the friction stir bonding method disclosed herein.

[0033] Figure 19 is a photographic image showing the end deformation of the sheet metal in another friction stir bonding method compared with the friction stir bonding method disclosed herein.

[0034] Figure 20 is a graph showing the shift in shoulder indentation and plate end deformation in other friction stirring point bonding methods compared with the friction stirring point bonding method disclosed herein. Detailed Implementation

[0035] The embodiments of this disclosure will now be described in detail with reference to the accompanying drawings. The friction stirring point bonding method disclosed herein is applicable to the manufacture of various joints formed by stacking and point-bonding two or more structural materials such as metal plates, frames, exterior materials, or columnar materials. The manufactured joints can be used as components of structures such as aircraft, railway vehicles, or automobiles.

[0036] [Composition of the friction stirring point connection device]

[0037] Figure 1 is a schematic diagram showing the configuration of a friction stirring point engagement device M according to an embodiment of the present disclosure.

[0038] The friction stirring point joining device M joins the upper plate 31 and lower plate 32 by softening them with frictional heat. The friction stirring point joining device M includes: a tool 1 for friction stirring point joining; a tool drive unit 2 for rotating and lifting the tool 1; and a controller C for controlling the movement of the tool drive unit 2. Furthermore, while "up" and "down" are indicated in Figure 1, this is merely for illustrative purposes and does not imply any limitation on the actual direction of use of the tool 1.

[0039] Tool 1 is supported by a tool fixing part. The tool fixing part may be, for example, the distal end of a multi-joint robot. A back pad 15 is disposed facing the lower end face of tool 1. At least two metal members that are to be joined are disposed between tool 1 and back pad 15. In Figure 1, an example is shown where a portion of an upper plate 31 having a flat plate and a portion of a lower plate 32 having a flat plate are overlapped in the vertical direction, forming an overlapping portion 30 disposed between tool 1 and back pad 15. Furthermore, tool 1 corresponds to the joining tool of this disclosure.

[0040] Tool 1 includes a pin 11 having a central axis extending along a specified axial direction, a shoulder 12, a clamping member 13, and a spring 14. The pin 11 is formed in a cylindrical shape and is configured such that its central axis extends vertically. The pin 11 is capable of rotating about the central axis as a pivot R, and is also capable of moving up and down, i.e., forward and backward, along the pivot R. Furthermore, during use of tool 1, the pivot R is aligned with the point engagement position W in the overlapping portion 30. Tool 1 is a compound tool in which the pin 11 and the shoulder 12 move independently.

[0041] The shoulder 12 is a hollow part that allows the pin 11 to be inserted and is formed into a cylindrical shape. The axis of the shoulder 12 is coaxial with the axis of rotation R, which is also the axis of the pin 11. The shoulder 12 rotates around the axis of rotation R and moves up and down, i.e., forward and backward, along the axis of rotation R.

[0042] The shoulder 12 and the pin 11 inserted into the hollow part rotate together around the axis of rotation R and move relative to each other in the direction of rotation R. That is, the pin 11 and the shoulder 12 can not only move up and down simultaneously along the axis of rotation R, but also can move independently such that one moves down while the other moves up.

[0043] The clamping member 13 is a cylindrical component with a hollow portion into which the shoulder 12 is inserted. The axis of the clamping member 13 is also coaxial with the rotation axis R. The clamping member 13 does not rotate around the axis but moves up and down, i.e., forward and backward, along the rotation axis R. When the pin 11 or the shoulder 12 is frictionally stirred, the clamping member 13 serves to surround their outer periphery. Due to the surrounding effect of the clamping member 13, the friction-stirring material is not allowed to scatter, and the contact area at the friction-stirring point can be made smooth.

[0044] A spring 14 is mounted on the upper end of the clamping member 13 and applies a downward force to the clamping member 13 in the direction of the overlapping portion 30. The clamping member 13 is mounted to the tool fixing portion by the spring 14. As shown in FIG1, the backing member 15 has a support surface 15A that supports the lower side of the overlapping portion 30, which is the object of engagement. The backing member 15 is a backing member that supports the overlapping portion 30 when the pin 11 or the shoulder 12 is pressed into the overlapping portion 30. The clamping member 13, which is subjected to a force by the spring 14, presses the overlapping portion 30 against the backing member 15.

[0045] The tool drive unit 2 includes a rotary drive unit 21 and a lifting drive unit 22. The rotary drive unit 21 includes a motor and drive gears, and drives the pin 11 and shoulder 12 to rotate about the pivot axis R. The rotary drive unit 21 corresponds to the rotary mechanism of this disclosure. The lifting drive unit 22 is a mechanism that moves the pin 11, shoulder 12, and clamping member 13 forward and backward along the pivot axis R, that is, it moves the pin 11, shoulder 12, and clamping member 13 up and down. The lifting drive unit 22 drives the pin 11 in a manner that causes the pin 11 to press into and retract from the overlapping portion 30. In addition, the lifting drive unit 22 moves the shoulder 12 forward and backward along the pivot axis R, and causes the shoulder 12 to press into and retract relative to the overlapping portion 30. The lifting drive unit 22 corresponds to the moving mechanism of this disclosure that enables the pin 11 and shoulder 12 to move independently along the axial direction extending from the pin 11. Furthermore, the lifting drive unit 22 moves the clamping member 13 toward the overlapping portion 30, and presses the overlapping portion 30 against the back pad member 15. At this time, the force of the spring 14 is activated. In other words, in this embodiment, it is configured to have three shafts: a first lifting shaft that integrally drives the pin 11, shoulder 12, and clamping member 13; a second lifting shaft that independently drives the pin 11; and a central rotating shaft.

[0046] The controller C includes a microcomputer and controls the movement of each part of the tool drive unit 2 by executing a specified control program. Specifically, the controller C controls the rotary drive unit 21 to cause the pin 11 and shoulder 12 to perform the required rotational movements. Furthermore, the controller C controls the lifting drive unit 22 to cause the pin 11, shoulder 12, and clamping member 13 to perform the required forward and backward movement movements. The controller C is equivalent to the control unit of this disclosure, and sets the rotation, movement amount, movement position, and applied pressure of each component described later.

[0047] The upper plate 31 is formed of metal, as shown in FIG1, and has an upper plate surface 31A and an upper plate back surface 31B. The upper plate surface 31A is the surface of the upper plate 31, corresponding to the upper surface of the upper plate 31 in FIG1. ​​The upper plate 31 corresponds to the first component of this disclosure. Similarly, the upper plate back surface 31B is the back surface of the upper plate 31, corresponding to the lower surface of the upper plate 31 in FIG1. ​​The upper plate surface 31A corresponds to the first surface of this disclosure, and the upper plate back surface 31B corresponds to the first back surface of this disclosure. Furthermore, as an example, the upper plate 31 is made of aluminum alloy. The upper plate 31 can be made of a stretched material or a casting. Additionally, chemical conversion treatment or electrodeposition coating can be performed on the upper plate 31.

[0048] The lower plate 32 is formed of metal, as shown in FIG. 1, and has a lower plate surface 32A and a lower plate back surface 32B. The lower plate surface 32A is the surface of the lower plate 32, which corresponds to the upper surface of the lower plate 32 in FIG. 1. Similarly, the lower plate back surface 32B is the back surface of the lower plate 32, which corresponds to the lower surface of the lower plate 32 in FIG. 1. The lower plate 32 corresponds to the second component of this disclosure. Furthermore, the lower plate surface 32A corresponds to the second surface of this disclosure, and the lower plate back surface 32B corresponds to the second back surface of this disclosure. Furthermore, as an example, the lower plate 32 is made of high-strength steel. The lower plate 32 can be made of aluminum alloy, low-carbon steel, or hot-stamped steel. Furthermore, the lower plate 32 can be subjected to non-coating treatment, zinc plating treatment, Al-Si coating treatment, chemical conversion treatment, electrodeposition coating, etc. Furthermore, an adhesive or sealant can be provided between the upper plate 31 and the lower plate 32. It should be noted that, as mentioned above, when the upper plate 31 is made of aluminum alloy and the lower plate 32 is made of high-strength steel, the melting point of the upper plate 31 is lower than that of the lower plate 32, and the hardness of the upper plate 31 is lower than that of the lower plate 32.

[0049] [How to use the tool]

[0050] Next, the method of using tool 1 as illustrated in this embodiment, namely the friction stirring point joining method, will be described. The methods of using the friction stirring point joining device M generally include: a pin-first process, in which the pin 11 of tool 1 is pressed into the overlapping portion of the joining parts in advance; and a shoulder-first process, in which the shoulder 12 is pressed into the overlapping portion of the joining parts in advance. In this embodiment, the shoulder-first process is used.

[0051] Figure 2 is a diagram showing process P11 to P15 of the friction stirring point joining method based on the aforementioned shoulder-first process. Figure 3 is a diagram showing the process flow of the friction stirring point joining method according to this embodiment. Figure 3 simplifies the process of friction stirring point joining the overlapping portion 30 of the upper plate 31 and the lower plate 32.

[0052] When performing friction stirring point engagement, firstly, as shown in step S1 of FIG3, an overlapping portion 30 is formed by the upper plate 31 and the lower plate 32. In the overlapping portion 30, at least a portion of the surface 32A of the lower plate abuts against the back surface 31B of the upper plate, and the upper plate 31 and the lower plate 32 are arranged in an overlapping manner.

[0053] Next, as shown in S2 of Figure 3, tool 1 is positioned in a designated location and rotated. Specifically, tool 1 is first positioned so that its axis of rotation R is parallel to the overlapping direction of the upper plate 31 and the lower plate 32, i.e., the vertical direction, so that tool 1 and the overlapping portion 30 face each other. Alternatively, tool 1's axis of rotation R can be positioned at an angle relative to the vertical direction. In this embodiment, with the axis of rotation R aligned with the predetermined point of contact W, the lower end face of tool 1 abuts against the upper plate surface 31A of the upper plate 31. At this time, as shown in process P11 of Figure 2, the clamping member 13 presses the overlapping portion 30 against the backing member 15 with the force of the spring 14. With the lower end face of tool 1 abutting against the upper plate surface 31A of the upper plate 31, the controller C controls the rotation drive unit 21 to rotate pin 11 and shoulder 12 around the axis of rotation R at a designated speed. Based on this rotation, the area where the pin 11 and shoulder 12 abut in the overlapping portion 30 is preheated by friction. That is, process P11 in FIG2 represents the preheating process of the overlapping portion 30.

[0054] Next, as shown in process P12 of Figure 2 and step S3 of Figure 3, a pressing process is performed to retract the pin 11 from the overlapping portion 30 and press the shoulder 12 into the overlapping portion 30. In this process, the controller C controls the lifting drive unit 22 to lower the shoulder 12 as shown in process P12 of Figure 2 and press it into the overlapping portion 30 while maintaining the rotation of the tool 1. On the other hand, the controller C raises the pin 11, i.e., retracts the pin 11. Meanwhile, the clamping member 13 remains stationary. The shoulder 12 is pressed into the overlapping portion 30 from the upper plate surface 31A to a pressing position deeper than the lower plate surface 32A. Furthermore, based on this action, as shown by arrow b1 in Figure 2, the material in the pressing area of ​​the shoulder 12 is stirred, and the overflow material OF that overflows from the overlapping portion 30 due to the pressing is released into the hollow space of the shoulder 12 created by the retraction of the pin 11. As a result, the base part of the anchor portion 4B in Figure 4, which will be described in detail later, is formed. Furthermore, during the pressing process, an axial force, i.e., an overall force, is applied to the pin 11, shoulder 12, and clamping member 13 as a whole. On the other hand, a clamping force is applied to the clamping member 13 based on the spring 14, pressing the clamping member 13 against the back pad 15. As a result, the pressing force of the tool 1 towards the coupling body 3 is equivalent to the force of the overall force minus the clamping force.

[0055] Next, as shown in process P13 of Figure 2 and step S4 of Figure 3, controller C controls the lifting drive unit 22 while maintaining the rotation of tool 1 to retract shoulder 12 from the pressed-in position and to lower pin 11 into overlap 30. This process represents the backfilling process of overflow material OF. In this process, controller C controls the lifting drive unit 22 to raise shoulder 12 and lower pin 11 on the other hand.

[0056] As pin 11 descends, as indicated by arrow b2, the overflow material OF released into the hollow space is backfilled into the pressed-in area of ​​shoulder 12.

[0057] Next, as shown in process P14 of Figure 2 and step S5 of Figure 3, a leveling process is performed to flatten the overlapping portion 30. In this process, the controller C controls the lifting drive unit 22 to rotate the pin 11 and the shoulder 12 with their lower ends positioned slightly lower than the upper plate surface 31A of the upper plate 31, thereby smoothing the point joint portion. As a result, the recess 4T of Figure 4, which will be described in detail later, is formed. Afterward, as shown in process P15 of Figure 2 and step S6 of Figure 3, the tool 1 is removed from the overlapping portion 30. Through the above process, as shown in Figure 1, a stirring joint portion 4 that joins the upper plate 31 and the lower plate 32 is formed. The stirring joint portion 4 corresponds to the joint portion of this disclosure.

[0058] [Regarding the cross-sectional structure of the joint]

[0059] Figure 4 is a schematic cross-sectional view illustrating the stirring joint 4 of the joint body 3 formed by the friction stirring point joining method described above. The stirring joint 4 has a joining bottom surface 4A, an anchor portion 4B, and a recess 4T. Furthermore, in Figure 4, the plate thicknesses T1 and T2 of the upper plate 31 and the lower plate 32 are shown.

[0060] The mating bottom surface 4A is based on the interface between the upper plate 31 and the lower plate 32, which is located deeper than the lower plate surface 32A, with the upper plate surface 31A as a reference, formed by the pressure applied by the shoulder 12. When viewed along the axis of rotation R, the mating bottom surface 4A has an annular shape corresponding to the lower part 12S of the shoulder 12. This annular shape is not limited to a shape formed by two perfect circles, and may sometimes be irregular depending on the conditions of the friction stirring point engagement. In other words, the mating bottom surface 4A has a generally annular shape when viewed from above.

[0061] Anchor portion 4B is a raised portion formed on the radially inner side of the joint bottom surface 4A by a portion of the lower plate 32, with the joint bottom surface 4A as a reference, to a position higher than the surface 32A of the lower plate. Anchor portion 4B is formed based on the overflow material OF that overflows from the overlapping portion 30 into the hollow space of the shoulder portion 12 during the pressing process, and its upper end is flattened by pin 11 during the backfilling process.

[0062] The recess 4T is positioned facing the mating bottom surface 4A and the anchor portion 4B in the overlapping direction of the upper plate 31 and the lower plate 32, i.e., in the vertical direction. It is essentially a recess formed by a partial depression of the upper plate surface 31A of the upper plate 31. It should be noted that, as mentioned earlier, the recess 4T can be actively formed by rotating the lower end face of the pin 11 and the lower end face of the shoulder 12 during the leveling process, with both positioned lower than the upper plate surface 31A of the upper plate 31. Alternatively, the lower end face of the pin 11 and the lower end face of the shoulder 12 can be aligned flush with the upper plate surface 31A of the upper plate 31 during the leveling process.

[0063] [Regarding deformation at the ends of the sheet metal]

[0064] Figures 18 and 19 are perspective views and photographic images showing the deformation of the ends of the sheet metal in other friction stir point joining methods compared with the friction stir point joining method according to this embodiment. Figure 19 is an image of the stirring joint portion 4 of the joint body 3 viewed from above along the same axis of rotation R as in Figure 1. The discloser has recently learned that, around the stirring joint portion 4 formed based on the friction stir point joining method, local deformation of the sheet metal occurs in its planar direction. In particular, it has been learned that, as shown in Figures 18 and 19, when an overlap portion 30 is formed such that the end 31T of the upper plate 31 follows the end 32T of the lower plate 32, and the stirring joint portion 4 is formed near the ends 31T and 32T, local deformation of the joint body 3 protrudes outward. Such deformation may limit the dimensions of the objects that can be joined (e.g., flange width, etc.) or affect the strength of the joint portion formed by the stirring joint portion 4, which is a concern.

[0065] To this end, the discloser conducted thorough experiments and repeated verifications, thereby discovering that the aforementioned deformation occurs during the pressing-in process of the shoulder 12. Specifically, Figure 20 is a graph showing the shift in the shoulder pressing-in amount and the deformation amount at the plate end in other friction stirring point joining methods compared with the friction stirring point joining method involved in this disclosure. Furthermore, Table 1 shows the experimental data corresponding to the graph in Figure 20. The data numbers in the following tables are appended for the purpose of organizing the data in each table and do not imply that data with the same number in different tables are the same data.

[0066]

[0067] In Figure 20, the horizontal axis represents the bonding time, the left vertical axis represents the shoulder indentation, and the right vertical axis represents the end deformation of the sheet metal in Figure 19. Solid lines correspond to the shoulder indentation, and dashed lines correspond to the end deformation. Furthermore, the zero point of the left vertical axis corresponds to the upper plate surface 31A of the upper plate 31. In this other friction-stirring point bonding method, the upper plate 31 is made of 1.1mm thick 6000 series aluminum alloy, and the lower plate 32 is made of 1.2mm thick 1.2GPa grade steel plate. Moreover, until the designated indentation position is reached, the indentation force of the shoulder 12, i.e., the force of the tool 1 in Figure 1 being pressed into the bonding body 3, is a constant value, for example, maintained at 7.7kN. The indentation position is set at a depth of 0.15mm deeper than the boundary between the upper plate back surface 31B and the lower plate surface 32A. Furthermore, the outer diameter of the shoulder 12 is 5.5mm, and the outer diameter of the pin 11 is 3.35mm. Their rotational speed was set at 1500 rpm. The distance L between the point of contact and the end of the upper plate 31 was 3 mm. Table 1 and Figure 20 were obtained based on the so-called stop action test, and were a combination of the results obtained by stopping the pressing of the shoulder 12 at each data position and visually measuring the end shape of the joint 3.

[0068] Furthermore, in Table 1, "target tool indentation depth" means the final target indentation depth of the shoulder 12, based on the lower plate surface 32A of the lower plate 32. Additionally, the "clamping member" input condition corresponds to the pressure (kN) applied by the clamping member 13, while "ST2-1" and "ST2-2" correspond to the pressure applied to the shoulder 12. In the embodiments described later, although "ST2-1" and "ST2-2" are varied, in this experiment, "ST2-1" and "ST2-2" are constant values. Furthermore, as mentioned earlier, the indentation pressure of the shoulder 12 on the engagement body 3 can be calculated as the difference between "ST2-1" and "ST2-2" and the pressure applied by the clamping member. Furthermore, in Table 1, "end distance" corresponds to the distance L described later, and "tool with or without tapering" indicates whether a tapered shape is applied to the distal end of the pin 11 and the shoulder 12.

[0069] Furthermore, in Table 1, information regarding the target stopping position of the shoulder 12 is expressed as "Indentation Process Stop Position" and "Backfilling Process Stop Position" (unit: mm). The "Indentation Process Stop Position" shown in each data point is the stopping position during the indentation process, while the "Backfilling Process Stop Position" shown in data 7 and 8 corresponds to the position where the shoulder 12 stops during backfilling after reaching the maximum indentation position. These are all represented by distances based on the surface of the upper plate 31. For example, in the case of data 7, after the shoulder 12 has traveled to the maximum indentation amount of 1.21 mm, it backfills to a position 0.5 mm away from the interface between the upper plate 31 and the lower plate 32 and 0.6 mm away from the surface of the upper plate 31, at which point the test is stopped.

[0070] As shown in Figure 20, it was confirmed that after the shoulder 12 is pressed into the upper plate surface 31A of the upper plate 31, the end deformation increases linearly up to the lower plate surface 32A of the lower plate 32, as indicated by the dashed line. Furthermore, the end deformation is limited after the shoulder 12 contacts the lower plate 32, which is formed of steel. Based on this, the discloser speculates that excessive pressure applied to the upper plate 31, which is formed of relatively soft aluminum alloy, is the cause of the end deformation, and therefore conceives a new approach: to improve the aforementioned pressing process.

[0071] [Regarding variable pressure control]

[0072] Figures 5A and 5B are diagrams illustrating a portion of the shoulder pre-process in the friction stirring point bonding method according to this embodiment. Figure 6 is a diagram illustrating the shift in shoulder indentation and plate end deformation in the friction stirring point bonding method according to this embodiment. Furthermore, Table 2 shows the experimental data corresponding to the graphs in Figure 6. The meanings of the parameters shown in Table 2 are the same as in Table 1.

[0073]

[0074] In this embodiment, the pressing process of process P12 in FIG2 and step S3 in FIG3 includes two steps. Specifically, as the first stage, in process P12A shown in FIG5A, the shoulder 12 is pressed into a designated reference position with a first pressure. As an example, this reference position is the interface between the upper back surface 31B of the upper plate 31 and the lower surface 32A of the lower plate 32 before pressing. Subsequently, in process P12B shown in FIG5B, the shoulder 12 is pressed into a designated pressing position from the reference position with a second pressure. The pressure change from the first pressure to the second pressure and the pressing of the shoulder 12 are performed continuously. FIG6 is a graph showing the shift in the shoulder pressing amount and the deformation amount at the plate end at this time, and is a graph corresponding to FIG20. In the experiment of FIG6, as in FIG20, the upper plate 31 is made of 6000 series aluminum alloy with a plate thickness of 1.1 mm, and the lower plate 32 is made of 1.2 GPa grade steel plate with a plate thickness of 1.2 mm. In this case, since the hardness of the upper plate 31 is lower than that of the lower plate 32, the first pressure is set to be less than the second pressure. As an example, the first pressure is 3 kN and the second pressure is 7.7 kN (refer to the pressure input conditions in Table 2). Other experimental conditions are the same as in Figure 20.

[0075] As shown in Figure 6, it was confirmed that when the shoulder 12 is pressed into the upper plate surface 31A of the upper plate 31 with a relatively low pressure, up to the lower plate surface 32A of the lower plate 32 (indicated by the dashed line), the end deformation is significantly reduced compared to Figure 20. Furthermore, even after the shoulder 12 contacts the lower plate 32 formed of steel, the end deformation remains small during the push-in process. Therefore, it is understood that by reducing the pressing load of the shoulder 12 within the upper plate 31 on the low-hardness side, the flow of material as shown by the solid arrow in process P12A of Figure 5A is suppressed, thereby significantly suppressing the deformation of the joint 3. In Figures 5A and 5B, as an example, during the pressing of the shoulder 12, overflow material fills to the distal end of the pin 11. However, to facilitate the flow of material below the shoulder 12 during the backfilling process in process P13 of Figure 2, the pin 11 can be raised to the point in Figures 5A and 5B where the material does not contact the distal end of the pin 11.

[0076] Based on the above concept, the discloser understands that it is possible to suppress deformation of the ends of the upper plate 31 and the lower plate 32 and excessive generation of the recess 4T. Specifically, when the hardness of the upper plate 31 is lower than the hardness of the lower plate 32, the first pressure is set to be less than the second pressure; on the other hand, when the hardness of the upper plate 31 is higher than the hardness of the lower plate 32, the first pressure is set to be greater than the second pressure.

[0077] Furthermore, in process P12 of Figure 2, with the pin 11 retracted relative to the upper plate surface 31A, the shoulder 12 is pressed into a designated reference position based on the lower plate surface 32A using a first pressure. Then, the shoulder 12 is pressed into a deeper position than the lower plate surface 32A using a second pressure.

[0078] In this case, preferably, the reference position is set within a range from the boundary between the back surface 31B of the upper plate and the surface 32A of the lower plate to 73% of the thickness of the component with lower hardness in the upper plate 31 and the lower plate 32. Alternatively, pressure can be switched on the side of the component with higher hardness.

[0079] Furthermore, preferably, when the upper plate 31 has a lower hardness than the lower plate 32, and the first pressure is set to P1 and the second pressure is set to P2, the first pressure and the second pressure are set such that P1 / P2 < 0.91. More preferably, the first pressure and the second pressure are set such that P1 / P2 < 0.7, and even more preferably, the first pressure and the second pressure are set such that P1 / P2 ≤ 0.65.

[0080] Furthermore, preferably, when the cross-sectional area of ​​the pin 11 is set to P and the cross-sectional area of ​​the shoulder 12 is set to S, the outer diameters of the pin 11 and the shoulder 12 are set respectively in a manner where S / P≤2.41.

[0081] Furthermore, more preferably, the outer diameters of the pin 11 and the shoulder 12 are set with an S / P ≤ 1.8 respectively.

[0082] Alternatively, the pin 11 and the shoulder 12 can be configured to face the overlapping portion 30 such that the shortest distance L between the outer periphery of the shoulder 12 and the end of the upper plate 31 when the shoulder 12 abuts against the upper plate surface 31A during pressing is 8 mm or less.

[0083] [Example]

[0084] The present disclosure is further described in detail below with reference to embodiments. The present disclosure is not limited to the following embodiments.

[0085] Figure 7 is a graph illustrating the relationship between the recess amount and TSS (Tensile Shear Strength) for an embodiment of the friction stirring point bonding method according to this disclosure. Furthermore, Table 3 shows the experimental data corresponding to the graph in Figure 7. In Table 3, 1 to 3 are comparative examples, and 4 to 6 are exemplary examples. Additionally, "Reference position input condition (mm)" means: the reference position set with the upper plate surface 31A of the upper plate 31 as a reference. Furthermore, "Adhesive application" means: whether or not adhesive is applied between the upper plate 31 and the lower plate 32.

[0086]

[0087] TSS is equivalent to the so-called tensile shear strength, which represents the load at which the stir joint 4 breaks when the upper plate 31 and lower plate 32 are stretched in directions parallel to and opposite to the upper plate surface 31A after the stir joint 4 is formed. That is, the larger the TSS value, the higher the tensile shear strength.

[0088] In the experiment shown in Figure 7, the upper plate 31 is a 1.1 mm thick 6000 series aluminum alloy, and the lower plate 32 is a 1.2 mm thick 1.2 GPa grade steel plate. That is, the upper plate 31 and the lower plate 32 are metals with different main elements. The rotation speed of tool 1 is 2000 rpm, the outer diameter of shoulder 12 is 5.5 mm, and the outer diameter of pin 11 is 3.35 mm. In the comparative example, the pressing force of shoulder 12 is 7.7 kN regardless of the position of shoulder 12. On the other hand, in the embodiment, a reference position is set at a depth of 1.06 mm from the surface 31A of the upper plate, and the pressing force at the position on the side of upper plate 31 relative to this reference position is set to 5 kN, and the pressing force at the position on the side of lower plate 32 relative to this reference position is set to 7.7 kN. In this case, the reference position is essentially equivalent to the interface between the back surface 31B of the upper plate and the surface 31A of the upper plate. Furthermore, the pressing position of the shoulder 12 is set at a depth of 0.15 mm from the lower plate surface 32A. In addition, in the aforementioned leveling process, with the aim of forming a recess 4T of approximately 0.30 mm in maximum, the lower shoulder portion 12S of the shoulder 12 and the lower pin portion 11S of the pin 11 are positioned slightly below the upper plate surface 31A.

[0089] As shown in Figure 7, in a comparative example where the pressure applied to the shoulder 12 during the pressing process is constant, the following result was obtained: a recess 4T larger than the target value was formed, with a depth of 0.33 mm or more but less than 0.35 mm. It is speculated that this phenomenon occurs because, during the pressing of the shoulder 12, a portion of the material is pressed out radially outward, thus ensuring sufficient overflow of material OF without flowing into the hollow space of the shoulder 12 shown in process P12 of Figure 2. If the overflow of material OF in such a hollow space is insufficient, the material will also be insufficient during the backfilling process, resulting in a recess 4T deeper than the target. Therefore, as described above, the situation where a portion of the material is pressed out radially outward during the pressing of the shoulder 12 causes deformation of the aforementioned joint 3.

[0090] On the other hand, in the embodiment where the pressing pressure on the relatively soft upper plate 31 was reduced, the following result was obtained: the recess 4T was distributed around 0.30 mm of the target, and the TSS value was larger than that of the comparative example. If the recess 4T is formed deeper than the target, cracks are easily generated in the thickness direction between the end of the recess 4T and the lower plate 32, that is, a fracture known as a plug fracture is easily generated. Therefore, as shown in FIG7, in the comparative example, a smaller TSS was obtained than that of the embodiment.

[0091] As described above, it was confirmed that by setting an appropriate pressing force according to the hardness of the sheet metal, the target recess 4T can be obtained, and the strength of the joint portion including the stirring joint 4 can be improved.

[0092] Figure 8 is a graph illustrating the relationship between the distance from the end of the plate of the joint 3 to the outer periphery of the shoulder 12 and the amount of end deformation, used to explain an embodiment of the friction stirring point bonding method according to this disclosure. The distance from the end of the plate to the outer periphery of the shoulder 12 is represented by the distance L in the aforementioned Figure 18. Furthermore, Table 4 shows the conditions for each experimental data corresponding to the graph in Figure 8.

[0093]

[0094] In the experiment shown in Figure 8, the materials, thicknesses, pin 11, and outer diameters of the shoulder 12 of the upper plate 31 and lower plate 32 were the same as in the experiment of Figure 7. Furthermore, in the comparative example, the pressing force of the shoulder 12 was 6 kN regardless of the pressing position. Moreover, in Example A, the outer diameter of the clamping member 13 was set to 16 mm, while in the comparative example and Example B, the outer diameter of the clamping member 13 was set to 10 mm. In Examples A and B, a position 0.8 mm deep from the surface 31A of the upper plate was set as the reference position, and the pressing force at the position on the upper plate 31 side was set to 2.5 kN, while the pressing force at the position on the lower plate 32 side was set to 6 kN. Other conditions were the same as in the experiment of Figure 7.

[0095] As shown in Figure 8, it was confirmed that, compared to the comparative example, in embodiments A and B, the deformation of the end of the joint 3 was reduced regardless of the outer diameter of the clamping member 13. In particular, even under the strict condition that the stirring joint 4 is close to the end of the joint 3 and the distance L is less than 8 mm, the deformation can be significantly reduced by controlling the applied pressure. Therefore, it is possible to configure the pin 11 and the shoulder 12 to face the overlapping portion such that the shortest distance L between the outer periphery of the shoulder 12 and the end of the upper plate 31 when the shoulder 12 abuts against the upper plate surface 31A during pressing is less than 8 mm.

[0096] Figure 9 is a diagram illustrating the relationship between the reference position and the amount of end deformation in an embodiment of the friction stirring point bonding method according to this disclosure. Furthermore, Table 5 shows the experimental data corresponding to the graph in Figure 9. The "distance from the interface between the upper and lower plates" in Table 5 is defined as follows: assuming the reference position 1.06 is the interface between the upper and lower plates, the difference between this 1.06 and the reference position input condition is set as the distance from the interface between the upper and lower plates. For example, in the second embodiment from the top, since the reference position input condition is 0.96, the distance from the interface between the upper and lower plates becomes 1.06 - 0.96 = 0.10.

[0097]

[0098] In the experiment shown in Figure 9, the materials, thicknesses, and outer diameters of the pin 11 and shoulder 12 of the upper plate 31 and lower plate 32 are the same as in the experiment of Figure 7. Furthermore, the distance L shown in Figure 18 is set to 3 mm. The rotational speed of tool 1 is 1500 rpm, the outer diameter of shoulder 12 is 5.5 mm, and the outer diameter of pin 11 is 3.35 mm. In the comparative example, the pressing force of shoulder 12 is 7.7 kN regardless of the pressing position. In the embodiment, the pressing force at the position on the upper plate 31 side relative to a specified reference position is set to 3 kN, and the pressing force at the position on the lower plate 32 side relative to a specified reference position is set to 7.7 kN. Furthermore, regarding the data shown in Figure 9 at the leftmost position with a reference position of -0.09, the pressing force at the position on the upper plate 31 side is set to 5 kN, and the pressing force at the position on the lower plate 32 side is set to 7.7 kN. Other conditions are the same as in the experiment of Figure 7. Furthermore, in the embodiment, friction stirring point engagement was performed by changing the reference position sequentially within the upper plate 31 under various conditions. Regarding the horizontal axis in FIG9, the reference position is represented by the value obtained by dividing the distance between the lower plate surface 32A and the reference position by the thickness of the upper plate 31, i.e., the upper plate thickness ratio.

[0099] As shown in Figure 9, the deformation at the end of the joint 3 in the comparative example ranges from 0.89 mm to 1.02 mm. On the other hand, the deformation in the embodiment shows a smaller result than that in the region where the thickness ratio of the upper plate 31 is less than 0.73 (located on the left side relative to the dashed line in Figure 9) at the reference position.

[0100] In this way, not only is the pressure applied to the shoulder 12 set low across the entire relatively soft upper plate 31, but even if the pressure is increased midway through pressing the upper plate 31, the deformation at the end of the joint 3 can be suppressed. However, to obtain more reliable deformation suppression, it is preferable to set the reference position in the region from the lower plate surface 32A to 0.4 times the upper plate thickness, and further to 0.35 times the upper plate thickness, and to press in with a relatively low first pressure at the position on the upper plate 31 side. Furthermore, if it is desired to suppress the deformation to at least a certain extent, the reference position can be set as a reference point to the portion where the upper plate back surface 31B meets the lower plate surface 32A, extending to 73% of the thickness of the component with lower hardness in the upper plate 31 and lower plate 32. Additionally, the pressure can be switched on the side of the component with higher hardness.

[0101] Furthermore, as shown in Figure 9, this experiment confirmed that even when the reference position is located at a position where the upper plate thickness ratio is -0.09, in other words, at a depth of 0.10 mm relative to the lower plate surface 32A of the lower plate 32, changing the applied pressure to a second pressure, the end deformation can be suppressed to 0.46 mm. Here, a negative upper plate thickness ratio means that the reference position is set within the lower plate 32. Thus, the pressure control involved in this invention can achieve a robust effect of suppressing end deformation even if the reference position is configured with a specified stagger at either side of the plate relative to the portion where the upper plate 31 and the lower plate 32 meet.

[0102] Figure 10 is a graph illustrating the relationship between the P1 / P2 pressure ratio and the amount of end deformation in an embodiment of the friction stirring point bonding method according to this disclosure. Furthermore, Table 6 shows the experimental data corresponding to the graph in Figure 10.

[0103]

[0104] In the experiment shown in Figure 10, the experimental conditions were the same as those in the embodiment of Figure 7, except that the applied pressure to the shoulder 12 and the rotation speed were 1500 rpm. In the embodiment of Figure 10, experiments were conducted under different conditions with respect to the magnitude of the first pressure P1, ranging from 2 kN to 7 kN. Furthermore, the magnitude of the second pressure P2 was 7.7 kN. As a result, the P1 / P2 ratio in the comparative example was 1.0, while the pressure ratios P1 / P2 in the embodiment ranged from 0.26 to 0.91.

[0105] As shown in Figure 10, if the first pressure P1 applied to the shoulder 12 within the upper plate 31 is at least slightly smaller than the second pressure P2, the effect of suppressing end deformation can be achieved. Moreover, the smaller P1 / P2 is, the smaller the end deformation can be maintained. For example, when the hardness of the upper plate 31 is lower than that of the lower plate 32, it is preferable to set the first pressure P1 and the second pressure P2 such that P1 / P2 < 0.91, as shown by the arrow in Figure 10.

[0106] Furthermore, as shown by the arrow in Figure 10, by setting the first pressure and the second pressure in such a way as P1 / P2<0.7, the amount of end deformation can be significantly reduced. Therefore, it is preferable to set the first pressure and the second pressure in such a way as P1 / P2≤0.65, so that the amount of end deformation can be reduced more reliably.

[0107] Figure 11 is a diagram illustrating the relationship between the plate assembly of the upper plate 31 and the lower plate 32 and the end deformation amount, used to explain an embodiment of the friction stirring point bonding method according to this disclosure. Furthermore, Table 7 shows the experimental data corresponding to the graph in Figure 11.

[0108]

[0109] Furthermore, Figures 12A, 12B, and 12C are perspective views illustrating the types of plate assemblies used to explain embodiments of the friction stirring point bonding method involved in this disclosure.

[0110] As shown in Figures 12A, 12B, and 12C, plate groups 1, 2, and 3 were used in this experiment, respectively. In plate group 1, the upper plate 31 is a 1.0mm thick 6000 series aluminum alloy, and the lower plate 32 is a 2.0mm thick 5000 series aluminum alloy. The hardness of the upper plate 31 is relatively lower than that of the lower plate 32. Furthermore, in plate group 2, the upper plate 31 is a 1.2mm thick 5000 series aluminum alloy, and the lower plate 32 is a 3.0mm thick 6000 series aluminum alloy.

[0111] The upper plate 31 has a relatively higher hardness than the lower plate 32. Furthermore, in plate assembly 3, the upper plate 31 is a 3.0mm thick 6000 series aluminum alloy, and the lower plate 32 is a 2.0mm thick 5000 series aluminum alloy. The upper plate 31 has a relatively lower hardness than the lower plate 32.

[0112] In the experiments with plate group 1 and plate group 2, the rotational speed of tool 1 was 2000 rpm, the outer diameter of shoulder 12 was 6.0 mm, and the outer diameter of pin 11 was 3.25 mm. Furthermore, in the experiment with plate group 3, the rotational speed of tool 1 was 2000 rpm, the outer diameter of shoulder 12 was 9.0 mm, and the outer diameter of pin 11 was 6.0 mm. In either case, the distance L shown in FIG. 18 was set to 3 mm. Furthermore, the pressing position of shoulder 12 was located 0.3 mm away from the lower plate surface 32A in plate group 1, 1.1 mm away from the lower plate surface 32A in plate group 2, and 0.5 mm away from the lower plate surface 32A in plate group 3. In Example I, the reference position was set at the boundary between the upper plate back surface 31B and the lower plate surface 32A. In Example II, the reference position was set 0.2 mm deeper than the lower plate surface 32A. In other words, in Embodiment II, the pressure applied to the shoulder 12 is set as the second pressure in the region from a position 0.2 mm deeper than the lower plate surface 32A to the final pressing position, i.e., 0.3 mm.

[0113] Furthermore, regarding the applied pressure, in the comparative example of plate assembly 1, the pressing pressure of the shoulder 12 was set to 8 kN. In Examples I and II, the first pressure P1 was set to 4 kN and the second pressure P2 was set to 8 kN. In the comparative example of plate assembly 2, the pressing pressure of the shoulder 12 was set to 9 kN. In Example I, the first pressure P1 was set to 9 kN and the second pressure P2 was set to 7 kN. In the comparative example of plate assembly 3, the pressing pressure of the shoulder 12 was set to 9.7 kN. In Example I, the first pressure P1 was set to 7 kN and the second pressure P2 was set to 9.7 kN.

[0114] As shown in Figure 11, it was confirmed that, compared to a comparative example where the pressing pressure of the shoulder 12 does not change in either plate group, the embodiment that sets a smaller pressing pressure in a relatively softer sheet material can suppress the amount of end deformation. In particular, it was confirmed that this tendency can also be applied to the following situations: the upper plate 31 and the lower plate 32 are dissimilar metals with the same main element, for example, two aluminum alloys with different constituent elements other than aluminum. Moreover, in the case where the lower plate 32 is relatively softer than the upper plate 31, as in plate group 2, the amount of end deformation can also be suppressed by setting the second pressure P2 to be smaller than the first pressure P1.

[0115] Furthermore, as shown in Figure 11, the following can be confirmed: as in Embodiment II of Plate Assembly 1, the reference position where the applied pressure is changed from the first pressure P1 to the second pressure P2 can be located on the side of the lower plate 32 relative to the lower plate surface 32A. This result is also consistent with the aforementioned reference position (upper plate thickness ratio) of -0.09 in Figure 9.

[0116] Figure 13 is a graph illustrating the relationship between the presence or absence of adhesive application and the amount of recess in an embodiment of the friction stirring point bonding method according to this disclosure. Furthermore, Table 8 shows the experimental data corresponding to the graph in Figure 13.

[0117]

[0118] The experimental conditions for the comparative and embodiment shown in Figure 13 are the same as those in Figure 7. When adhesive is applied, before friction stirring point bonding of the upper plate 31 and lower plate 32 is performed, i.e., before the shoulder 12 is pressed in, adhesive is pre-applied between the back surface 31B of the upper plate and the surface 32A of the lower plate. As shown in Figure 13, it was confirmed that, regardless of whether adhesive is applied, the embodiment can suppress the amount of indentation less compared to the comparative example. Furthermore, in the comparative example where adhesive was pre-applied as described above, the amount of indentation increased significantly, and there was a tendency for end deformation to occur accordingly. Even in such cases, by setting a smaller pressing force on the shoulder 12 in the relatively soft upper plate 31, the amount of indentation can be reduced and the amount of end deformation can be suppressed. Furthermore, a sealing material can be pre-applied between the back surface 31B of the upper plate and the surface 32A of the lower plate instead of adhesive. This is also true below.

[0119] Figure 14 is a graph illustrating the relationship between the presence or absence of adhesive application and TSS in an embodiment of the friction stirring point bonding method according to this disclosure. Furthermore, Figure 9 shows the experimental data corresponding to the graphs in Figure 14 and Figure 15 described later. Additionally, Table 9 separately lists the recesses in both the TSS connector and the CTS connector.

[0120]

[0121] As shown in Figure 14, similar to Figure 7, among the four bars on the left, the upper plate 31 is made of 6000 series aluminum alloy with a thickness of 1.1 mm, and the lower plate 32 is made of 1.2 GPa grade steel plate with a thickness of 1.2 mm. No plating treatment is applied to the steel plates. Furthermore, in the comparative example, the pressing force of the shoulder 12 is 7.7 kN regardless of its position. In this embodiment, a reference position is set at a depth of 1.06 mm from the surface 31A of the upper plate, and the pressing force at the position on the upper plate 31 side relative to this reference position is set to 3 kN, while the pressing force at the position on the lower plate 32 side relative to this reference position is set to 7.7 kN. All other conditions are the same as in Figure 7.

[0122] On the other hand, in the two bars on the right side of Figure 14, the upper plate 31 is made of 6000 series aluminum alloy with a thickness of 1.1 mm, and the lower plate 32 is made of Al-Si coated 1.5GPa grade steel with a thickness of 1.4 mm. The conditions for pressing pressure, reference position, and pressing position are the same as those described above.

[0123] As shown in Figure 14, in the comparative example, while the specified TSS performance was met without the adhesive applied, the TSS performance decreased when the adhesive was applied. This phenomenon, as described above, also corresponds to an increase in the amount of recess. On the other hand, as shown in the embodiment, it was confirmed that even with the adhesive applied, the TSS performance could be improved by setting a smaller pressing pressure on the shoulder 12 in the upper plate 31. The same performance could be obtained when the lower plate 32 was made of Al-Si coated 1.5GPa grade steel with a thickness of 1.4mm.

[0124] It should be noted that even in either case, regardless of the presence or absence of adhesive, the increase in indentation can be suppressed, thereby restoring the strength of the joint 3.

[0125] Figure 15 is a graph illustrating the relationship between the presence or absence of adhesive application and CTS (Cross Tension Strength) for explaining an embodiment of the friction-stirring point bonding method according to this disclosure. The experimental conditions in each bar of Figure 15 are the same as in Figure 14. The CTS on the vertical axis of Figure 15 is the cross tensile strength, where the upper plate 31 and the lower plate 32 are stacked to form a cross shape in top view, and the stirring joint 4 is formed at their intersection. The CTS corresponds to the load at which fracture occurs when the upper plate 31 and the lower plate 32 are subsequently peeled apart.

[0126] As shown in Figure 15, it was confirmed that, under the condition that the lower plate 32 is an uncoated 1.2 GPa grade steel plate and there is no adhesive coating, the performance of the CTS in the embodiment was improved compared to the comparative example, and the strength of the stirring joint 4 was improved. Furthermore, it was also confirmed in the embodiment that the performance of the CTS decreased to some extent due to the application of adhesive.

[0127] Figure 16 is a graph illustrating the relationship between the distance L from the end of the plate to the outer periphery of the shoulder and the amount of end deformation, used to explain an embodiment of the friction stirring point bonding method according to this disclosure. Furthermore, Table 10 shows the experimental data corresponding to the graph in Figure 16.

[0128]

[0129] Figure 16 illustrates the following experimental data: the outer diameters of pin 11 and shoulder 12 are different combinations, and the pressing force of shoulder 12 is set relatively small. The legend φ5-3 in this figure indicates a combination of a 5mm outer diameter for shoulder 12 and a 3mm outer diameter for pin 11. Furthermore, the inner diameter of shoulder 12 is set approximately equal to the outer diameter of pin 11 to allow for relative movement and rotation. The same applies to other outer diameter combinations in this figure. Additionally, the S / P ratio in Figure 16 represents the ratio of the cross-sectional areas of pin 11 (P) and shoulder 12 (S). For the conditions shown in the legend of Figure 16, the S / P ratios from top to bottom are 1.78, 2.05, 1.70, 1.33, and 2.41.

[0130] Under all conditions, the rotational speed of tool 1 is 2000 rpm. Furthermore, the upper plate 31 is made of 1.0 mm thick 6000 series aluminum alloy, and the lower plate 32 is made of 1.2 mm thick 980 MPa grade steel. Other pressing and pressurizing conditions are the same as in Figure 7.

[0131] Referring to Figure 16, it was confirmed that, including the case where the S / P ratio is at its maximum (φ6-3.25), the end deformation of the joint 3 can be suppressed under all conditions where the S / P ratio is 0 or higher and 2.41 or lower. Furthermore, it was confirmed that the suppression of end deformation is particularly effective in the region where the S / P ratio is 0 or higher and 1.8 or lower. Therefore, it is particularly preferable to set the outer diameters of the shoulder 12 and the pin 11 in a manner that satisfies these conditions.

[0132] Furthermore, Table 11 shows examples of the dimensions of the shoulder 12 and pin 11 in the embodiments described above. It was confirmed that under these conditions, by controlling the first pressure and the second pressure, it is possible to suppress end deformation of the lower plate 32 and excessive formation of the recess 4T. All diameters are in mm.

[0133]

[0134] In addition, Table 12 shows examples of the shoulder and pin dimensions involved in the comparative examples shown above.

[0135]

[0136] Furthermore, the publisher of this disclosure has confirmed that, including the embodiments described above, the effects of this disclosure are particularly significant within the following scope.

[0137] Regarding the thickness of the upper plate 31 and the lower plate 32, it is 0.5 mm or more and 5 mm or less, preferably 1 mm or more and 3 mm or less. In addition, regarding the speed of the tool, it is 500 rpm or more and 3000 rpm or less, preferably 1500 rpm or more and 2000 rpm or less.

[0138] <Modified Implementation>

[0139] In the above embodiments and examples, the upper plate 31 and the lower plate 32 were softened by frictional heat to join them, but this disclosure is not limited to this. Figures 17A and 17B are schematic diagrams of the joined bodies illustrating the friction stirring point joining method according to a modified embodiment of this disclosure. This disclosure can also be applied to joining three or more plates by overlapping them.

[0140] Specifically, as shown in Figure 17A, this type of joint can be applied to joints where only the top two pieces are joined, with a third piece positioned below them. In Figure 17A, the upper plate 31 and the middle plate 33 are joined by a friction stirring point, forming a joint bottom surface 4A. On the other hand, the lower plate 32 is joined to the middle plate 33 by spot welding or adhesive. In this case, the pressing force can be adjusted according to the hardness relationship between the upper plate 31 and the middle plate 33.

[0141] Furthermore, as shown in Figure 17B, the joint can be formed by joining two materials equivalent to the upper plate with a third piece of steel. For example, if the upper plate 31 and the middle plate 33 are made of the same material, they can be directly pressed in without changing the pressing force between them. On the other hand, if the upper plate 31 and the middle plate 33 are made of different materials, it is advisable to change the pressure from the upper plate 31 to the middle plate 33 during pressing. In addition, if the upper plate 31, the middle plate 33, and the lower plate 32 are made of different materials, it is advisable to change the pressing force in three stages. For example, if the hardness of each component is in the relationship of medium, small, and large from the upper plate 31 side, the pressing force can also be adjusted to medium, small, and large.

[0142] Thus, this disclosure focuses on the hardness of two specified components in a joint consisting of three or more layers of components, and can be applied to the setting of the pressing force in those two components.

[0143] [Summary of this disclosure]

[0144] The specific implementation methods described above include the following disclosed content with the following structure.

[0145] The first aspect of this disclosure relates to a friction stirring point joining method, which joins a first member and a second member by softening them through frictional heat. The first member and the second member are each formed of metal. The first member has a first surface and a first back surface, and the second member has a second surface and a second back surface. The friction stirring point joining method includes the following steps: preparing a friction stirring point joining device comprising a pin and a shoulder, the shoulder being cylindrical and having a hollow portion for inserting the pin; arranging the first member and the second member in such a way that at least a portion of the second surface faces the first back surface and the first member overlaps with the second member; and configuring the pin and the shoulder to overlap the second surface. The parts face each other; a first pressure and a second pressure for pressing into the shoulder are set in the following manner: when the hardness of the first component is lower than the hardness of the second component, the first pressure is set to be less than the second pressure; when the hardness of the first component is higher than the hardness of the second component, the first pressure is set to be greater than the second pressure; with the pin retracted relative to the overlapping part, the shoulder is pressed into a designated reference position set with the second surface as a reference using the first pressure; the shoulder is pressed into a pressing position deeper than the second surface using the second pressure; and the shoulder is retracted from the pressing position and the pin is inserted into the overlapping part.

[0146] According to this configuration, when the first and second components are joined at the friction stirring point, the pressure applied during shoulder pressing is adjusted according to the hardness of each component. This prevents excessive pushing of the components to the outside and suppresses deformation of the joint around the joint point. Furthermore, since excessively large recesses are prevented at the joint point, unstable fracture of the joint is reduced.

[0147] Furthermore, the friction stirring point bonding method according to the second aspect of this disclosure, in the friction stirring point bonding method according to the first aspect, further includes the step of setting the reference position in a range from the boundary between the first back surface and the second surface to 73% of the plate thickness of the component with lower hardness in the first component and the second component.

[0148] According to this configuration, when performing friction stirring point engagement, it is possible to further suppress the excessive pushing of the component to the outside.

[0149] Furthermore, the friction stirring point joining method according to the third aspect of this disclosure, in the friction stirring point joining method according to the first aspect, further includes the following steps: using a component whose hardness is lower than that of the second component as the first component and the second component; and setting the first pressure and the second pressure in such a way that P1 / P2 < 0.91 when the first pressure is set to P1 and the second pressure is set to P2.

[0150] According to this configuration, when friction stirring point engagement is performed, when the shoulder moves from the first member with relatively lower hardness to the second member with higher hardness, it is possible to further suppress the excessive pushing of the first member to the outside.

[0151] Furthermore, the friction stirring point bonding method according to the fourth aspect of this disclosure, in the friction stirring point bonding method according to the first aspect, further includes the following steps: using a component whose hardness is lower than that of the second component as the first component and the second component; and setting the first pressure and the second pressure in such a way that P1 / P2<0.7.

[0152] According to this configuration, when friction stirring point engagement is performed, when the shoulder moves from the first member with relatively lower hardness to the second member with higher hardness, it is possible to further suppress the excessive pushing of the first member to the outside.

[0153] Furthermore, the friction stirring point bonding method according to the fifth aspect of this disclosure, in the friction stirring point bonding method according to the first aspect, further includes the following steps: using a component whose hardness is lower than that of the second component as the first component and the second component; and setting the first pressure and the second pressure in such a way as satisfying P1 / P2≤0.65.

[0154] According to this configuration, when friction stirring point engagement is performed, when the shoulder moves from the first member with relatively lower hardness to the second member with higher hardness, it is possible to further suppress the excessive pushing of the first member to the outside.

[0155] Furthermore, the friction stirring point joining method according to the sixth aspect of this disclosure, in the friction stirring point joining method according to any one of the first to fifth aspects, further includes the step of using metals with different main elements as the first component and the second component.

[0156] According to this configuration, even when metals with different main elements are used as the first and second components, deformation of the joint body around the point joint position can be suppressed.

[0157] Furthermore, the friction stirring point joining method according to the seventh aspect of this disclosure, in the friction stirring point joining method according to any one of the first to fifth aspects, further includes the step of using dissimilar metals with the same main element as the first component and the second component.

[0158] According to this configuration, even when dissimilar metals with the same main element are used as the first and second components, deformation of the joint body around the point joint location can be suppressed.

[0159] Furthermore, the friction stirring point joining method according to the eighth aspect of this disclosure, in the friction stirring point joining method according to any one of the first to seventh aspects, further includes the step of: providing an adhesive or sealing material between the first back surface of the first member and the first surface of the second member before the shoulder is pressed in.

[0160] According to this configuration, by providing an adhesive or sealing material between the first and second components before friction stirring bonding, it is possible to maintain a tight seal between the two components in areas other than the joint. On the other hand, in such a case, it is possible for the TSS (Total Stress Saturation) of the joint to decrease, but by adjusting the pressure during shoulder pressing according to the hardness of each component, the TSS can be improved. Furthermore, it is also possible to suppress excessive increase in the amount of recess.

[0161] Furthermore, the friction stirring point joining method according to the ninth aspect of this disclosure, in the friction stirring point joining method according to any one of the first to eighth aspects, further includes the following step: when the cross-sectional area of ​​the pin is set as P and the cross-sectional area of ​​the shoulder is set as S, the outer diameters of the pin and the shoulder are respectively set in such a way that S / P≤2.41.

[0162] According to this configuration, by setting the relative thickness of the shoulder relative to the pin within a specific range, it is possible to suppress, in particular, the excessive pushing of the component to the outside during friction stirring point engagement.

[0163] Furthermore, the friction stirring point joining method according to the 10th aspect of this disclosure, in the friction stirring point joining method according to any one of the 1st to 8th aspects, further includes the following step: when the cross-sectional area of ​​the pin is set to P and the cross-sectional area of ​​the shoulder is set to S, the outer diameters of the pin and the shoulder are respectively set in such a way that S / P≤1.8.

[0164] According to this configuration, by setting the relative thickness of the shoulder relative to the pin within a specific range, it is possible to suppress, in particular, the excessive pushing of the component to the outside during friction stirring point engagement.

[0165] Furthermore, the friction stirring point joining method according to the 11th aspect of this disclosure, in the friction stirring point joining method according to any one of the 1st to 10th aspects, further includes the following steps: forming the overlapping portion such that the end of the first member follows the end of the second member, and configuring the pin and the shoulder to face the overlapping portion such that the shortest distance between the outer periphery of the shoulder and the end of the first member when the shoulder abuts against the first surface during the pressing is 8 mm or less.

[0166] According to this configuration, even when the distance between the end of the first member and the outer periphery of the shoulder is as small as 8 mm or less, it is possible to suppress excessive pushing of the member to the outside and to prevent significant deformation of the shape of the joint.

[0167] Furthermore, the friction stirring point joining device according to the 12th aspect of this disclosure is a device for joining a first member and a second member by softening them through frictional heat. The first member and the second member are each formed of metal, the first member having a first surface and a first back surface, and the second member having a second surface and a second back surface. The friction stirring point joining device includes: a joining tool comprising a pin and a shoulder, the shoulder being cylindrical and having a hollow portion for inserting the pin; a rotation mechanism capable of rotating the joining tool; a moving mechanism capable of independently moving the pin and the shoulder in the direction in which the pin extends; and a control unit controlling the rotation mechanism and the moving mechanism; wherein the control unit sets a first pressure and a second pressure for pressing into the shoulder in such a way that, when the hardness of the first member is lower than the hardness of the second member, the first pressure is applied... When the hardness of the first member is higher than that of the second member, the first pressure is set to be greater than the second pressure. The control unit controls the rotation mechanism and the movement mechanism in such a way that, with the first member and the second member arranged in an overlapping portion where at least a portion of the second surface faces the first back surface and the first member and the second member overlap, and the pin and the shoulder are arranged facing the overlapping portion, the pin is retracted relative to the overlapping portion, and the shoulder is pressed from the first surface side to a designated reference position set with reference to the second surface with the first pressure, and the shoulder is pressed from the reference position to a pressing position deeper than the second surface with the second pressure, and then the shoulder is retracted from the pressing position and the pin is inserted into the overlapping portion.

[0168] According to this configuration, when the first and second components are joined at the friction stirring point, the pressure applied during shoulder pressing is adjusted according to the hardness of each component, thereby preventing excessive pushing of the components to the outside. As a result, deformation of the joint body around the point joint location can be suppressed. Furthermore, since excessively large recesses can be prevented at the point joint location, breakage of the joint body can be reduced.

[0169] Furthermore, in the friction stirring point joining device according to the 13th aspect of this disclosure, in the friction stirring point joining device according to the 12th aspect, the control unit sets the reference position in the range from the boundary between the first back surface and the second surface to 73% of the plate thickness of the component with lower hardness in the first component and the second component.

[0170] According to this configuration, when performing friction stirring point engagement, it is possible to further suppress the excessive pushing of the component to the outside.

[0171] Furthermore, in the friction stirring point joining device according to the 14th aspect of this disclosure, when the hardness of the first member is lower than the hardness of the second member, the control unit sets the first pressure and the second pressure in such a way that P1 / P2 < 0.91 when the first pressure is set to P1 and the second pressure is set to P2.

[0172] According to this configuration, when friction stirring point engagement is performed, when the shoulder moves from the relatively less hard second member to the higher second member, it is possible to further suppress the excessive pushing of the first member to the outside.

[0173] Furthermore, in the friction stirring point joining device according to the 15th aspect of this disclosure, when the hardness of the first member is lower than the hardness of the second member, and when the first pressure is set to P1 and the second pressure is set to P2, the control unit sets the first pressure and the second pressure in such a way that P1 / P2 < 0.7.

[0174] According to this configuration, when friction stirring point engagement is performed, when the shoulder moves from the relatively less hard second member to the higher second member, it is possible to further suppress the excessive pushing of the first member to the outside.

[0175] Furthermore, in the friction stirring point joining device according to the 16th aspect of this disclosure, when the hardness of the first member is lower than the hardness of the second member, the control unit sets the first pressure and the second pressure such that P1 / P2≤0.65 when the first pressure is set to P1 and the second pressure is set to P2.

[0176] According to this configuration, when friction stirring point engagement is performed, when the shoulder moves from the relatively less hard second member to the higher second member, it is possible to further suppress the excessive pushing of the first member to the outside.

Claims

1. A method for joining friction stirring points, characterized in that, The first and second components are joined by softening them through frictional heat. The first and second components are each formed of metal. The first component has a first surface and a first back surface, and the second component has a second surface and a second back surface. The friction stirring point joining method includes the following steps: preparing a friction stirring point joining device comprising a pin and a shoulder, the shoulder being cylindrical and having a hollow portion for inserting the pin; arranging the first and second components in such a way that at least a portion of the second surface faces the first back surface and the first component overlaps with the second component; configuring the pin and the shoulder to face the overlap; and setting them in the following manner. The first and second pressures for pressing into the shoulder are as follows: when the hardness of the first member is lower than the hardness of the second member, the first pressure is set to be less than the second pressure; when the hardness of the first member is higher than the hardness of the second member, the first pressure is set to be greater than the second pressure. With the pin retracted relative to the overlapping portion, the first pressure is used to press the shoulder from the first surface side to a designated reference position set with the second surface as a reference. The second pressure is used to press the shoulder from the reference position to a pressing position deeper than the second surface. Finally, the shoulder is retracted from the pressing position, and the pin enters the overlapping portion.

2. The friction stirring point bonding method according to claim 1, characterized in that... It also includes the following steps: The reference position is set in the range from the boundary between the first back surface and the second surface to 73% of the plate thickness of the component with lower hardness in the first and second components.

3. The friction stirring point bonding method according to claim 1, characterized in that... It also includes the following steps: The first component is used as the first component and the second component, and the hardness of the first component is lower than that of the second component; and when the first pressure is set to P1 and the second pressure is set to P2, the first pressure and the second pressure are set in such a way that P1 / P2<0.

91.

4. The friction stirring point bonding method according to claim 1, characterized in that... It also includes the following steps: The first component is used as the first component and the second component, and the hardness of the first component is lower than that of the second component; and the first pressure and the second pressure are set in such a way that P1 / P2<0.

7.

5. The friction stirring point joining method according to claim 1, characterized in that... It also includes the following steps: The first component is used as the first component and the second component, and the hardness of the first component is lower than that of the second component; and the first pressure and the second pressure are set in such a way that P1 / P2≤0.

65.

6. The friction stirring point joining method according to any one of claims 1 to 5, characterized in that... It also includes the following steps: The first component and the second component use metals with different main elements.

7. The friction stirring point joining method according to any one of claims 1 to 5, characterized in that... It also includes the following steps: Both the first and second components use dissimilar metals with the same main element.

8. The friction stirring point joining method according to any one of claims 1 to 7, characterized in that... It also includes the following steps: Before the shoulder is pressed in, an adhesive or sealant is applied between the first back surface of the first member and the first surface of the second member.

9. The friction stirring point joining method according to any one of claims 1 to 8, characterized in that... It also includes the following steps: When the cross-sectional area of ​​the pin is set as P and the cross-sectional area of ​​the shoulder is set as S, the outer diameters of the pin and the shoulder are set respectively in the manner of S / P≤2.

41.

10. The friction stirring point bonding method according to any one of claims 1 to 8, characterized in that... It also includes the following steps: When the cross-sectional area of ​​the pin is set as P and the cross-sectional area of ​​the shoulder is set as S, the outer diameters of the pin and the shoulder are set respectively in the manner of S / P≤1.

8.

11. The friction stirring point bonding method according to any one of claims 1 to 10, characterized in that... It also includes the following steps: The overlapping portion is formed such that the end of the first member follows the end of the second member, and the pin and the shoulder are configured to face the overlapping portion such that the shortest distance between the outer periphery of the shoulder and the end of the first member when the shoulder abuts against the first surface during the pressing is 8 mm or less.

12. A friction stirring point connection device, characterized in that, The first and second components are joined by softening them through frictional heat. The first and second components are each formed of metal. The first component has a first surface and a first back surface, and the second component has a second surface and a second back surface. The friction stirring point joining device includes: a joining tool comprising a pin and a shoulder, the shoulder being cylindrical and having a hollow portion for inserting the pin; a rotating mechanism capable of rotating the joining tool; a moving mechanism capable of independently moving the pin and the shoulder in the direction of pin extension; and a control unit controlling the rotating mechanism and the moving mechanism. The control unit sets a first pressure and a second pressure for pressing into the shoulder in such a way that, when the hardness of the first component is lower than the hardness of the second component, the first pressure is set to be less than the second pressure. When the hardness of the first component is higher than that of the second component, the first pressure is set to be greater than the second pressure. The control unit controls the rotation mechanism and the movement mechanism in such a way that, with the first component and the second component arranged in an overlapping portion where at least a portion of the second surface faces the first back surface and the first component and the second component overlap, and the pin and the shoulder are arranged facing the overlapping portion, the pin is retracted relative to the overlapping portion, and the shoulder is pressed from the first surface side to a designated reference position set with the second surface as a reference with the first pressure, and the shoulder is pressed from the reference position to a pressing position deeper than the second surface with the second pressure. Then, the shoulder is retracted from the pressing position and the pin enters the overlapping portion.

13. The friction stirring point connection device according to claim 12, characterized in that, The control unit sets the reference position in the range from the boundary between the first back surface and the second surface to 73% of the plate thickness of the component with lower hardness in the first and second components.

14. The friction stirring point engagement device according to claim 12 or 13, characterized in that, When the hardness of the first component is lower than that of the second component, when the first pressure is set to P1 and the second pressure is set to P2, the control unit sets the first pressure and the second pressure in such a way that P1 / P2 < 0.

91.

15. The friction stirring point engagement device according to claim 12 or 13, characterized in that, When the hardness of the first component is lower than that of the second component, when the first pressure is set to P1 and the second pressure is set to P2, the control unit sets the first pressure and the second pressure in such a way that P1 / P2<0.

7.

16. The friction stirring point engagement device according to claim 12 or 13, characterized in that, When the hardness of the first component is lower than that of the second component, when the first pressure is set to P1 and the second pressure is set to P2, the control unit sets the first pressure and the second pressure in such a way that P1 / P2≤0.65.

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