WO2022210248A1

WO2022210248A1 - Inspection method for friction stir welded part, and welding device

Info

Publication number: WO2022210248A1
Application number: PCT/JP2022/013905
Authority: WO
Inventors: 俊祐春名; 慎太郎深田; 良司大橋; 遼一波多野
Original assignee: 川崎重工業株式会社
Priority date: 2021-03-30
Filing date: 2022-03-24
Publication date: 2022-10-06
Also published as: JP2022154726A

Abstract

The friction stir welded part is formed by press-fitting a friction stir tool, from a first-member side, into an overlap portion that includes the first member and a second member arranged at a lower layer of the first member, in a state in which the second member is supported by a backing material, and thereby forming a friction stir part, and press-fitting a fastening body into the friction stir part from the first-member side. This inspection method for the friction stir welded part detects whether a part of the fastening body is in abutment against the backing material.

Description

Friction Stir Weld Inspection Method and Welding Apparatus

The present disclosure relates to an inspection method for a friction stir welded portion formed by joining overlapping portions of two or more members using friction stir and a fastening body, and a welding apparatus for the overlapping portion.

Metal members, resin members, and thermoplastic resin members mixed with fiber reinforced materials are used as structural members for aircraft, railroad vehicles, automobiles, and the like. When manufacturing the structure, it may be necessary to overlap and join two or more members. As a technique for this joining, joining using a fastening body such as a rivet and joining using friction stir are known.

Patent Document 1 discloses a joining method using blind rivets. In this joining method, a blind rivet with a flange is driven from the surface side of the overlapped portion of the two members to penetrate the overlapped portion. After that, by expanding and deforming the penetrating portion of the blind rivet on the back side of the overlapping portion, a joint portion is formed in which the overlapping portion is sandwiched between the expanded portion and the flange portion.

In the joint portion manufactured by the method of Patent Document 1, the bulging portion and the flange portion are exposed to the outside. For this reason, it is possible to relatively easily inspect whether or not the joint is normally performed visually or by image processing. However, it is difficult to inspect whether or not the fastening body is press-fitted into the overlapping part in a normal shape for the joint formed by placing the fastening body in such a manner that it does not penetrate the overlapping part.

Japanese Patent No. 5250429

The present disclosure provides an inspection method that can accurately inspect a friction stir welded portion formed by joining overlapping portions of two or more members using friction stir and a fastening body, and a joint that can perform the inspection method. The purpose is to provide an apparatus.

A method for inspecting a friction stir weld according to one aspect of the present disclosure includes: backing the second member side to an overlapping portion including a first member and a second member arranged in a lower layer of the first member; A friction stir weld formed by press-fitting a friction stir tool from the first member to form a friction stir portion while being supported by a material, and press-fitting a fastening body into the friction stir portion from the side of the first member. 2. The inspection method of 1, wherein it is detected whether or not a portion of the fastener abuts the backing material.

According to this inspection method, it can be detected that the fastening body penetrates the friction stir portion and the second member and comes into contact with the backing material. In other words, the fastening body passes through the friction stir portion without undergoing deformation intended for the fastening body, such as forming an interlocking portion with the base material of the second member. Poor enforcement can be detected. Therefore, it is possible to accurately inspect the friction stir welded portion in which the fastening body is driven without penetrating the overlapping portion.

A joining device according to another aspect of the present disclosure is a joining device that joins an overlapping portion including a first member and a second member arranged in a lower layer of the first member, wherein from the first member side A friction stir tool that is press-fitted into the overlapping portion to form a friction stir portion in the overlapping portion, a press-fitting tool that press-fits the fastening body from the first member into the friction stir portion, and the overlapping portion on the second member side. a backing material that supports from the backing material; and detection means for detecting whether or not a part of the fastening body comes into contact with the backing material.

According to this welding apparatus, in a series of steps of press-fitting the fastening body into the friction stir part to form the friction stir welded part, it is possible to detect whether or not part of the fastening body comes into contact with the backing material. becomes possible. In other words, it is possible to detect defective work in which the fastening body penetrates the friction stir portion without undergoing the intended deformation during the process of forming the friction stir weld. Therefore, it is possible to provide a bonding apparatus that forms a quality-assured bonded portion.

According to the present disclosure, an inspection method capable of accurately inspecting a friction stir welded portion formed by joining overlapping portions of two or more members using friction stir and a fastening body, and the inspection method can be performed. It is possible to provide an excellent joining device.

FIG. 1 is a schematic diagram showing the configuration of a double-acting friction stir spot welding apparatus capable of executing the method for inspecting a friction stir weld according to the present disclosure. FIG. 2A is a cross-sectional view showing an overlapping portion between a first member and a second member; FIG. 2B is a partially broken side view of a rivet (fastening body). FIG. 2C is a cross-sectional view of a joined body joined using both friction stir and rivets. FIG. 3 is a block diagram showing the electrical configuration of the friction stir spot welding device. FIG. 4 is a cross-sectional view showing a preparation state for friction stir welding with riveting. FIG. 5 is a cross-sectional view sequentially showing implementation steps (A) to (D) of friction stir welding with riveting. FIG. 6 is a diagram showing a process chart of an inspection method for a riveted friction stir welded portion according to the present embodiment. FIG. 7 is a schematic diagram showing an example of an inspection process for a rivet penetration error. FIG. 8 is a schematic diagram showing another example of the inspection process for rivet penetration errors. FIG. 9 is a schematic diagram showing an example of the float inspection process for the head portion of the rivet. FIG. 10A is a cross-sectional view showing a joint where the head portion is not lifted. FIG. 10B is a cross-sectional view showing a joint portion in which the head portion is lifted. FIG. 11 is a schematic diagram showing an example of an inspection process for the expansion degree of the cylindrical body portion of the rivet. FIG. 12 is a schematic diagram showing another example of the inspection process for the expansion degree of the cylindrical portion of the rivet. FIG. 13 is a cross-sectional view showing how the rivet is externally heated.

Hereinafter, embodiments of the present disclosure will be described in detail based on the drawings. The friction stir weld to be inspected in the present disclosure is, for example, two or more structural members such as plates, frames, exterior materials, or columnar materials made of metal, thermoplastic resin, thermoplastic composite material, etc. It is a joint formed by joining. A joined body provided with this friction stir welded portion becomes a structural member of, for example, an aircraft, a railroad vehicle, or an automobile.

[Configuration of friction stir spot welding device]
FIG. 1 is a schematic diagram showing the configuration of a double-acting friction stir spot welding device M (joining device) capable of executing the friction stir weld inspection method according to the present disclosure. The friction stir spot welding apparatus M is attached to the arm tip of an articulated robot having a robot arm having six movable joint axes, for example. The friction stir spot welding device M may be attached to a mechanical device that moves only up and down along one axis. Furthermore, a single-acting friction stir spot welding device can also be used.

The friction stir spot welding apparatus M comprises a double-acting friction stir spot welding tool 1, a tool driving section 2 for rotating and vertically driving the tool 1, and a tool fixing section 17 for fixing the tool 1 to a workpiece. including. In addition, although FIG. 1 shows directions of “up” and “down”, this is for convenience of explanation and is not intended to limit the actual usage direction of the tool 1 . In this embodiment, the work is an overlapping portion 30 in which a first member 31 and a second member 32 are superimposed in the vertical direction, and finally constitutes the joined body 3 by friction stir spot welding. The tool 1 of the present embodiment serves both as a tool for performing friction stir and as a tool for press-fitting a fastening body corresponding to a rivet 5, which will be described later, into the friction stir portion.

The tool 1 includes a pin member 11, a shoulder member 12, a clamp member 13 and a spring 14. The pin member 11 is a member formed in a cylindrical shape, and is arranged so that the direction of its axis extends in the vertical direction. The pin member 11 is rotatable about the axis line as a rotation axis R, and is capable of advancing and retreating along the rotation axis R in the vertical direction indicated by an arrow Z1. Note that when the tool 1 is used, the tool 1 is fixed to the overlapping portion 30 so that the rotation axis R and the point joining position W in the overlapping portion 30 are aligned.

The shoulder member 12 is positioned so as to cover the outer circumference of the pin member 11 . The shoulder member 12 is a cylindrical member having a hollow portion into which the pin member 11 is inserted. The axis of the shoulder member 12 is coaxial with the axis of the pin member 11, that is, the rotation axis R. The shoulder member 12 is rotatable about the same rotation axis R as the pin member 11, and is vertically movable along the rotation axis R in the vertical direction indicated by the arrow Z2. The shoulder member 12 and the pin member 11 inserted in the hollow portion are capable of relative movement in the direction of the rotation axis R while both rotating about the rotation axis R. As shown in FIG. That is, the pin member 11 and the shoulder member 12 can not only move up and down simultaneously along the rotation axis R, but can also move independently such that one moves down and the other moves up.

The clamp member 13 is a cylindrical member having a hollow portion into which the shoulder member 12 is inserted. The axial center of the clamp member 13 is also coaxial with the rotation axis R. The clamp member 13 does not rotate about its axis, but can move forward and backward along the rotation axis R in the vertical direction indicated by the arrow Z3. The clamp member 13 serves to surround the outer periphery of the pin member 11 or the shoulder member 12 when performing friction stir. The enclosure of the clamping member 13 prevents the friction stir material from scattering and allows smooth finishing of the friction stir point welded portion.

The spring 14 is attached to the upper end portion 131 of the clamp member 13 so as to extend upward. The spring 14 urges the clamping member 13 in a direction toward the overlapping portion 30, here downward.

The tool fixing section 17 includes a rotating tool fixture 171 and a clamp fixture 172 . The rotary tool fixture 171 is arranged above the shoulder member 12 in which the pin member 11 is inserted, and supports the pin member 11 and the shoulder member 12 . The clamp fixture 172 supports the clamp member 13 via the spring 14 . Also, the clamp fixture 172 supports the rotating tool fixture 171 via a rotation drive section 23, which will be described later.

A backing material 15 is arranged facing the lower end surface of the tool 1 . The backing material 15 includes a support plane 151 that abuts against the workpiece to be joined, which is the lower surface side of the overlapping portion 30 in this embodiment. The backing material 15 is a member that supports the overlapping portion 30 from the back surface when the pin member 11 or the shoulder member 12 and the rivet 5 described later are press-fitted into the overlapping portion 30 . The backing material 15 is held by the tip portion 161 of the C-shaped frame 16 . Clamping member 13 biased by spring 14 presses overlapping portion 30 against backing material 15 . The tool 1 is thereby fixed to the overlapping portion 30 . Incidentally, the C-shaped frame 16 is, for example, a frame attached to the tip of the robot arm.

The tool drive section 2 includes a pin drive section 21, a shoulder drive section 22 and a rotation drive section 23. The pin drive unit 21 is a mechanism for advancing and retreating the pin member 11 along the rotation axis R, in this case, for raising and lowering the pin member 11 . The pin driving portion 21 drives the lower end portion 11T of the pin member 11 to descend toward the overlapping portion 30 or to rise relative to the overlapping portion 30 . For example, a direct acting actuator can be used as the pin drive unit 21 . As the linear motion actuator, an actuator composed of a servomotor and a rack/pinion, or an actuator composed of a servomotor and a ball screw, or the like can be used.

The shoulder drive unit 22 is a mechanism that moves the shoulder member 12 back and forth along the rotation axis R. The shoulder driving portion 22 drives the lower end portion 12T of the shoulder member 12 to be press-fitted into the overlapping portion 30 and retracted. As the shoulder driving portion 22, a linear motion actuator similar to that described above can be used. The shoulder driving portion 22 of the present embodiment is a mechanism for lifting and lowering the tool fixing portion 17 itself that supports the pin member 11 , the shoulder member 12 and the clamp member 13 . Therefore, the movements of the pin member 11, the shoulder member 12 and the clamp member 13 in the directions of arrows Z1, Z2 and Z3 shown in FIG.

However, the pin member 11 can move forward and backward independently of the shoulder member 12 and the clamp member 13 by being driven by the pin driving portion 21 . For example, the pin member 11 can be driven upward by the pin driving portion 21 even when the shoulder driving portion 22 is driving the shoulder member 12 downward. In addition, the biasing force of the spring 14 also acts on the clamp member 13 when it is lowered by the shoulder driving portion 22 and the lower end portion 13T of the clamp member 13 is in contact with the overlapping portion 30 . Due to said biasing force, the clamping member 13 presses the overlap 30 against the backing material 15 and secures the tool 1 against the overlap 30 .

The rotary drive unit 23 includes a servomotor, a drive gear, etc., and is held by the clamp fixture 172 . The rotation drive unit 23 rotates the rotary tool fixture 171 . This rotational drive causes the pin member 11 and the shoulder member 12 supported by the rotary tool fixture 171 to rotate about the rotation axis R. As shown in FIG.

[Overview of friction stir welding]
The inspection method according to the present disclosure is intended to inspect a friction stir welded portion formed by joining overlapping portions of two or more members using friction stir and a fastening body. An outline of this friction stir welding will be explained. FIG. 2A is a diagram showing the overlapping portion 30 between the first member 31 and the second member 32 before friction stir is performed. FIG. 2B is a partially broken side view of the rivet 5 (fastening body) that is press-fitted into the friction stir part 4, and FIG. ) is a sectional view of FIG.

FIG. 2A shows an example in which the first member 31 and the second member 32 are configured by stacking a plurality of thin layer sheets 33 . As the thin layer sheet 33, a sheet such as a prepreg made by impregnating an array of continuous fibers with a thermoplastic resin can be used. The first member 31 and the second member 32 may each be a member composed of a sheet of fiber-reinforced thermoplastic resin molding, or may be a thermoplastic resin member that does not contain metal or fiber reinforcement. FIG. 2A shows an example in which the first member 31 and the second member 32 have the same thickness. good.

The overlapping portion 30 has a mating surface BD where the joint surface 31A (lower surface) of the first member 31 and the joint surface 32A (upper surface) of the second member 32 are in direct contact. The overlapping portion 30 is not limited to such a two-layer structure. It includes the first member 31 and the second member 32 arranged in the lower layer of the first member 31, and one or more other layers may be interposed between them. The tool 1 described above is press-fitted into the overlapped portion 30 from the first member 31 side, and friction stir is performed with a predetermined point welding position W as the axis, thereby forming the friction stir portion 4 . Further, the rivet 5 is press-fitted into the friction stir portion 4 from the first member 31 side to complete the construction of the joined body 3 .

Referring to FIG. 2B, the rivet 5 is made of a conductive titanium alloy such as Ti-6Al-4V, and has a cylindrical head portion 51 and a cylindrical cylindrical body continuously provided below the head portion 51. 52. The head portion 51 has a diameter larger than that of the cylindrical body portion 52 , and the large diameter portion serves as a collar portion 54 . The head portion 51 is made of a solid body and has a top surface 51H that receives a pressing force from the tool 1 . The tubular body portion 52 includes an upper end portion 521 integrally connected to the head portion 51 and a lower end portion 522 that becomes a leading end portion when the overlapping portion 30 is driven. The cylindrical body portion 52 has a columnar hollow region 523 therein in order to be easily deformable. The lower end portion 522 is also the opening edge of the hollow area 523 and has an annular edge shape.

A self-piercing rivet, for example, can be used as the rivet 5 described above. The rivet 5 is partially deformed by being driven into the overlapping portion 30 , and generates an engaging force that integrates the first member 31 and the second member 32 . Incidentally, instead of the self-piercing rivet, various joining members that are partially deformable may be used as the fastening member.

As shown in FIG. 2C, the rivet 5 is press-fitted into the overlapping portion 30 in the friction stir portion 4 . The friction stir part 4 is formed with a depth extending from the first member 31 side to a part of the second member 32 , and has a side peripheral surface 41 and a bottom surface 42 . In the present embodiment, it is planned that the entire length of the cylinder portion 52 is press-fitted into the friction stir portion 4 (overlapping portion 30 ), and that the lower end surface of the head portion 51 comes into contact with the friction stir portion 4 . After being press-fitted into the friction stir portion 4 , the lower end portion 522 of the cylindrical body portion 52 is expanded and deformed into a bell shape, and is also press-fitted into the base material portion of the second member 32 surrounding the friction stir portion 4 . That is, the lower end portion 522 forms the interlock portion 53 by entering the base material portion below the bottom surface 42 of the friction stir portion 4 and radially outside the side peripheral surface 41 . The joint strength of the joined body 3 can be increased by the locking effect of the interlock portion 53 alone and the clamping effect of the interlock portion 53 and the flange portion 54 .

In this embodiment, an example in which the entire length of the cylindrical body portion 52 is press-fitted into the overlapping portion 30 is shown, but a predetermined length of the cylindrical body portion 52 may be press-fitted into the overlapping portion 30 . In this case, a gap of a predetermined length is formed between the upper surface 30U of the overlapping portion 30 and the lower end surface of the head portion 51. As shown in FIG. Alternatively, a rivet 5 in which the head portion 51 and the cylindrical body portion 52 have the same diameter, or a rivet 5 in which the head portion 51 has a smaller diameter than the cylindrical body portion 52 may be used. Furthermore, after press-fitting the rivet 5 , the head portion 51 may be rolled so as to have a larger diameter than the friction stir portion 4 .

[Control Configuration of Friction Stir Spot Welding Device]
FIG. 3 is a block diagram showing the control configuration of the friction stir spot welding device M. As shown in FIG. The friction stir spot welding apparatus M includes a controller 61 (control section), an input section 62 and an inspection section 63 as a control configuration. The friction stir spot welding apparatus M also includes an ammeter 26, a stroke sensor 27, and a temperature detector 28 as hardware components not shown in FIG.

The controller 61 is composed of a microcomputer or the like, and comprehensively controls the operation of each part of the tool drive unit 2 and the operation of the inspection unit 63 by executing a predetermined control program. Specifically, the controller 61 controls the pin driving section 21 to independently move the pin members 11 forward and backward. In addition, the controller 61 controls the shoulder driving section 22 to cause the pin member 11, the shoulder member 12 and the clamp member 13 to move forward and backward as required. By these forward and backward movements, the tool 1 is fixed to the overlapped portion 30, the pin member 11 or the shoulder member 12 is press-fitted into the overlapped portion 30, and the like. Further, the controller 61 controls the rotation drive unit 23 to rotate the pin member 11 and the shoulder member 12 around the rotation axis R during the appropriate period of the forward and backward movement, and friction stir at the spot welding position W of the overlapping portion 30. let it run.

As a method of using the above-described double-acting friction stir spot welding tool 1, there are a pin-first process and a shoulder-first process. When friction stir is performed in the pin-preceding process, the controller 61 causes the pin member 11 of the tool 1 to be press-fitted into the overlapping portion 30 in advance to perform friction stir, and raises, that is, retracts the shoulder member 12 . In the subsequent refilling process, the pin member 11 is raised and retracted, while the shoulder member 12 is lowered.

On the other hand, when friction stir is performed in the shoulder preceding process, the controller 61 causes the shoulder member 12 of the tool 1 to be pressed into the overlapping portion 30 in advance to perform friction stir, while the pin member 11 is raised, that is, retracted. Let In the subsequent refilling process, the shoulder member 12 is raised and retracted, while the pin member 11 is lowered. In the embodiment shown in FIG. 5, which will be described later, an example in which friction stir is performed in the shoulder preceding process will be described in detail.

The input unit 62 consists of a keyboard, a touch panel, etc., and receives required data input to the controller 61 . The input data includes, for example, various parameters related to friction stir welding control, the thickness and material of the workpiece, the press-fitting depth of the tool 1, coordinate data of the point welding position W, and the like.

The tool drive section 2 includes an encoder 24 (measurement means) and a pin current-carrying section 25 (detection means) in addition to the pin drive section 21, shoulder drive section 22, and rotation drive section 23 described above. In the present embodiment, electric motors are used as drive sources for the pin drive section 21, the shoulder drive section 22, and the rotation drive section 23, respectively. The encoders 24 are attached to the electric motors of the pin driving section 21 and the shoulder driving section 22, respectively, and output electrical signals that lead to specification of the height positions of the lower end portion 11T of the pin member 11 and the lower end portion 12T of the shoulder member 12.

The pin conducting section 25 includes a DC voltage source, and applies a DC voltage to the pin member 11 during a penetration error inspection of the rivet 5, which will be described later. The ammeter 26 (detection means) detects the current flowing between the pin member 11 of the tool 1 and the backing material 15 during the penetration error inspection.

The stroke sensor 27 (measuring means) is a sensor that detects the relative position between the shoulder member 12 and the clamp member 13 . When the stroke sensor 27 detects that the shoulder member 12 and the clamp member 13 are at the same position while the clamp member 13 is clamping the overlapping portion 30 , the lower end portion 12T of the shoulder member 12 is positioned above the overlapping portion 30 . It is in contact with the upper surface 30U.

The temperature detection unit 28 (shape estimation means) measures the temperature of the friction stir welded portion (overlapping portion 30/joint body 3) during or after welding. As the temperature detector 28, various non-contact or contact temperature measuring devices can be used. Thermography can be exemplified as the former, and thermocouples can be exemplified as the latter as preferred temperature measuring devices.

The inspection unit 63 performs various inspection operations on the joined body 3 using both the friction stirrer 4 and the rivet 5 . The inspection unit 63 functionally includes a contact current detection unit 64 (detection means), a motor current detection unit 65 (detection means), a tool position detection unit 66 (measurement means), a clearance calculation unit 67 (measurement means), a shape An estimating section 68 (shape estimating means) and a determining section 69 (shape estimating means) are provided. These functional units will be described in detail together with their operations when the inspection process is described with reference to FIGS.

The contact current detector 64 determines whether the current flowing between the pin member 11 and the backing material 15 has exceeded a predetermined threshold based on the current value measured by the ammeter 26 . Further, the contact current detector 64 determines that the backing material 15 contacts the lower end portion 522 of the rivet 5 when the current exceeds the predetermined threshold value.

The motor current detection unit 65 detects the motor current of the electric motor that is the drive source of the pin drive unit 21 or the motor current of the electric motor that is the drive source of the shoulder drive unit 22 . Further, the motor current detector 65 determines that the backing material 15 has come into contact with the lower end portion 522 of the rivet 5 when the motor current exceeds a predetermined threshold value. Since the inspection functions of the contact current detection section 64 and the motor current detection section 65 are substantially the same, either one of them may be omitted.

Based on the output value of the encoder 24, the tool position detection section 66 calculates the lowered positions of the pin member 11 and the shoulder member 12, that is, the height positions of the

lower end portions

11T and 12T. The height position of the lower end portion 12T of the shoulder member 12 may be calculated by the tool position detection section 66 based on the output value of the stroke sensor 27.

Based on the calculation result of the height position of the tool position detection unit 66, the gap calculation unit 67 calculates the distance between the lower end of the head portion 51 of the rivet 5 and the upper surface 30U of the overlapping portion 30, in other words, the upper surface of the first member 31. Find the interval. At this time, the gap calculator 67 refers to the thickness information of the head section 51 that is given from the input section 62 in advance.

The shape estimating section 68 performs a process of estimating the expansion degree or deformation degree of the cylindrical portion 52 of the rivet 5 based on the temperature information of the friction stir welded portion detected by the temperature detecting section 28 . The determining unit 69 compares the expanded shape of the cylindrical body 52 estimated by the shape estimating unit 68 with a pre-stored template to determine whether the expanded shape satisfies the required degree of expansion. determine whether

[Friction stir welding method using rivets]
Next, a specific example of a method of forming a friction stir welded portion using the tool 1 for friction stir spot welding and using the rivet 5 in the overlapping portion 30 together will be described with reference to FIGS. 4 and 5. FIG. In this embodiment, an example is shown in which the tool 1 is caused to friction stir the overlapping portion 30 in the shoulder preceding process. Also, an example in which the tool 1 performs both the friction stir process and the process of press-fitting the rivet 5 into the friction stir portion 4 is shown. The press-fitting step of the rivet 5 may be performed by a press-fitting tool separate from the tool 1 .

FIG. 4 is a cross-sectional view showing a preparatory process for friction stir welding that also uses rivets. In the preparation step, the overlapping portion 30 is formed in which the first member 31 and the second member 32 are overlapped with each other at least partially in contact with each other. FIG. 4 shows an example in which the first member 31 is arranged on the tool side (upper side) and the second member 32 is arranged on the backing material 15 side (lower side). The lower surface 30B of the overlapping portion 30 is supported by the backing material 15, and the lower end surface of the tool 1 is in contact with the upper surface 30U.

In the preparation process, an operation of pre-loading the tool 1 with the rivet 5 to be driven is also performed. Specifically, the controller 61 shown in FIG. 3 operates the pin driving portion 21 to lift the pin member 11 and create a space for accommodating the rivet 5 in the hollow portion of the shoulder member 12 . That is, the lower end portion 11T of the pin member 11 is raised relative to the lower end portion 12T of the shoulder member 12 by the height of the rivet 5 or more to provide an accommodation space near the opening of the lower end of the shoulder member 12 . After an appropriate time, the rivet 5 is loaded into the accommodation space. Subsequently, a clamping operation of the tool 1 to the overlapping portion 30 is performed. At this time, the rotation axis R ( FIG. 1 ) of the tool 1 is aligned with the point joining position W in the overlapping portion 30 . In this state, the clamping member 13 presses the overlapping portion 30 against the backing material 15 at the lower end portion 13T with the biasing force of the spring 14 . The lower end portion 12T of the shoulder member 12 is also in contact with the upper surface 30U.

FIG. 5 is a cross-sectional view sequentially showing steps (A) to (D) of friction stir welding with riveting. Process (A) of FIG. 5 shows a friction stir process in which the shoulder member 12 of the tool 1 is press-fitted into the overlapping portion 30 to perform friction stir. The controller 61 controls the shoulder drive section 22 and the rotation drive section 23 to lower the shoulder member 12 while rotating it about its axis at high speed, and starts press-fitting the shoulder member 12 into the overlapping portion 30 . On the other hand, the controller 61 controls the pin drive section 21 to retract the pin member 11 upward so as to release the resin material overflowing from the press-fitting. The clamping member 13 is immovable. As a result, friction stir is performed centering on the point welding position W. Since the pin member 11 is moved upward to accommodate the rivet 5, the retracting operation of the pin member 11 may be omitted.

When the shoulder member 12 rotating at high speed is press-fitted into the overlapping portion 30 , the material of the overlapping portion 30 is friction-stirred in the press-fit region of the shoulder member 12 . The material overflowing from the overlapping portion 30 due to the press-fitting of the shoulder member 12 is released into the hollow portion within the shoulder member 12 . By the friction stir, the material of the press-fitting region is softened, and the friction stir portion 4 is formed in the overlapping portion 30 . For example, when the first member 31 and the second member 32 are formed of a laminate of prepreg thin-layer sheets 33, the continuous fibers of the thin-layer sheet 33 are cut and pulverized in the friction stirrer 4. . This facilitates subsequent setting and deformation of the rivet 5 .

The process (B) of FIG. 5 is a diagram showing a process of refilling the material overflowing from the overlapping portion 30 in the previous friction stir process. In the backfilling process, the shoulder drive 22 raises the shoulder member 12 . If the pin member 11 has been raised, it is lowered. Due to this operation, the softened material flows into the area occupied by the vicinity of the lower end portion 12T of the shoulder member 12 in the friction stir portion 4 . Therefore, the material overflowing from the overlapping portion 30 is also filled back into the press-fit region. By executing the above steps, the friction stir portion 4 having the cylindrical side peripheral surface 41 with the depth d and the disk-shaped bottom surface 42 is formed in the overlapping portion 30 .

The process (C) in FIG. 5 is a diagram showing the implementation status of the rivet 5 driving process. In the driving step, the rivet 5 is press-fitted into the friction stir portion 4 from the first member 31 side. Specifically, the pin driving portion 21 lowers the pin member 11 to apply a pressing force to the head portion 51 to push the rivet 5 into the overlapping portion 30 . The rivet 5 is loaded in the accommodation space in advance so that the top surface 51H of the head portion 51 faces the lower end portion 11T of the pin member 11 . Therefore, when the pin member 11 descends, the rivet 5 also descends and enters the friction stir portion 4 from the lower end portion 522 side. In this embodiment, since the tool 1 for friction stir spot welding is used as a tool for press-fitting the rivet 5 , there is no need to separately prepare a press-fitting tool for driving the rivet 5 .

Step (D) in FIG. 5 is a diagram showing a step of deforming a part of the driven rivet 5 to form the interlock portion 53 . In this step, after the rivet 5 reaches the second member 32, the rivet 5 is deformed so that part of the rivet 5 enters the base material portion of the second member 32 around the friction stir portion 4. An interlock portion 53 is formed. In the present embodiment, the cylindrical body portion 52 is deformed into a bell shape with an enlarged lower end portion 522, and the enlarged lower end portion 522 is press-fitted into the base material portion, whereby the interlocking is performed. A portion 53 is formed.

As the rivet 5 is pushed down by the pin member 11 from the state of step (C) in FIG. The portion below the bottom surface 42 is the base material portion and is not softened. Also, the overlapping portion 30 is supported by the backing material 15 at a position directly below the bottom surface 42 . Therefore, when the pin member 11 continues to press the rivet 5 after reaching the bottom surface 42, the cylindrical body portion 52 is deformed into a bell shape as shown in step (D) of FIG.

That is, the lower end portion 522 is not only press-fitted into the base material portion below the friction stir portion 4 beyond the bottom surface 42 , but also expands in the radial direction to extend beyond the side peripheral surface 41 of the friction stir portion 4 . It comes to be press-fitted also to the said base material part of a side. Among them, the portion press-fitted into the base material portion beyond the side peripheral surface 41 is an interlock that exerts an anchor effect in the peeling direction of the first member 31 and the second member 32, here in the vertical direction. A part 53 is formed. Note that the deformation of the cylindrical portion 52 of the rivet 5 may occur before reaching the second member 32 . For example, a deformation mode may be adopted in which, after being press-fitted into the friction stir portion 4 , the tubular body portion 52 gradually begins to expand and deform in the area of the first member 31 , and expands and deforms further after reaching the bottom surface 42 .

After that, the tool 1 is removed from the overlapping portion 30, and construction at one joint is completed. The state after the construction is completed is as shown in FIG. 2C. If necessary, a step of crushing the head portion 51 of the rivet 5 is additionally performed. For example, in the crushing step, the head portion 51 is pressed so that the diameter of the head portion 51 is larger than that of the friction stir portion 4 . According to the joining method described above, the combined use of the friction stir portion 4 and the rivet 5 by the tool 1 allows the overlapping portion 30 to be joined with excellent joining strength.

[Inspection flow for friction stir welded joints with rivets]
In order to assure the quality of the friction stir welded joint using the rivet 5, it is necessary to inspect whether the rivet 5 is normally driven into the friction stir joint 4 or not. Since the rivet 5 of the present embodiment is driven in a manner that does not penetrate the overlapped portion 30, it is difficult to determine whether the rivet is good or bad by visual inspection or visual inspection using image processing. Therefore, in the present embodiment, the riveted and friction stir welded portion is inspected by a method that does not depend on the appearance inspection.

FIG. 6 is a diagram showing a process chart of an inspection method for a riveted friction stir welded portion according to the present embodiment. The inspection process executed first is a penetration error inspection of the rivet 5 (step S1). A penetration error refers to a state in which the cylinder portion 52 of the rivet 5 driven into the friction stir portion 4 penetrates the overlapping portion 30 . The occurrence of penetration means that the expected expansion deformation of the cylindrical body portion 52 is not performed, and as a result, the interlock portion 53 is not formed. In this case, the rivet 5 does not exhibit the effect of locking the overlapping portion 30 .

Since the overlapping portion 30 is supported by the backing material 15, the lower end portion 522 of the tubular body portion 52, which is a part of the fastening body, comes into contact with the backing material 15 when a penetration error occurs. In the present embodiment, this abutment is inspected based on the state of conduction between the pin member 11 pressing the rivet 5 and the backing material 15 (FIG. 7), or the pin driving portion 21 or the rotation driving portion 23 is inspected. It is inspected based on the fluctuation of the motor current of the electric motor which is the driving source of the (Fig. 8). As a result of these inspections, if contact of the rivet 5 with the backing material 15 is detected (NO in step S2), the joint is determined to be defective (step S8). On the other hand, if the rivet 5 is not in contact with the backing material 15 (YES in step S2), then the inspection in step S3 is performed.

In step S3, a floating inspection of the head portion 51 of the rivet 5 is performed. The floating of the head portion 51 refers to a state in which the lower end portion 522 of the head portion 51 does not contact the upper surface 30U of the overlapping portion 30, that is, the upper surface of the friction stir portion 4, and a gap is generated between them. If the head portion 51 floats, it leads to the cylindrical body portion 52 not being press-fitted into the friction stir portion 4 to the predetermined press-fitting depth d. In this case, it is assumed that the rivet 5 does not exhibit a sufficient locking effect due to insufficient press-fitting.

The head portion 51 is pressed by the lower end portion 11T of the pin member 11 . Therefore, if the thickness of the head portion 51 is known, the difference between the lowered position of the lower end portion 11T and the position of the upper surface 30U of the overlapping portion 30 can be obtained as the distance between the lower end portion 522 of the head portion 51 and the upper surface 30U. can be asked for. The position of the upper surface 30U can be obtained from the height position of the lower end portion 12T of the shoulder member 12 that is in contact with the upper surface 30U. In this embodiment, the height positions of the

lower end portions

11T and 12T are calculated based on the output values of the encoders 24 attached to the electric motors of the driving sources of the pin driving portion 21 and the shoulder driving portion 22 (FIG. 9). . If there is a gap corresponding to the floating of the head portion 51 (NO in step S4), the joint portion is determined to be defective (step S8). On the other hand, if the gap does not exist (YES in step S4), then the inspection in step S5 is executed.

In step S5, the expansion degree inspection of the tubular portion 52 of the rivet 5 is performed. The expansion degree of the cylindrical body portion 52 is an index indicating how much the diameter of the lower end portion 522 is increased compared to the original diameter by deforming the cylindrical body portion 52 into a bell shape. be. Even if the rivet 5 does not pass through the overlapped portion 30 and no lift is detected in the head portion 51, there may be a case where the cylindrical body portion 52 is not expanded and deformed as expected. If the cylindrical portion 52 is insufficiently expanded or has a distorted expanded shape, it is assumed that the interlock portion 53 that exerts a sufficient locking effect will not be formed.

In general, the first member 31 and the second member 32 forming the overlapping portion 30 and the rivet 5 are often made of different materials. In the previous example, the former is a fiber-reinforced thermoplastic resin and the latter is a titanium alloy, and both have different thermal conductivities. Therefore, by measuring the temperature of the friction stir welded portion where the rivet 5 is driven, it is possible to estimate the expansion shape of the cylindrical portion 52 based on the temperature difference between the rivet 5 and its surroundings. In this embodiment, the case where the temperature measurement is performed by a thermography 281 (FIG. 11) and the case where a thermocouple 282 embedded in the backing material 15 is used (FIG. 12) are exemplified. If the expansion degree of the cylindrical body portion 52 is abnormal (NO in step S6), the joint portion is determined to be defective (step S8). On the other hand, if the expansion degree of the cylindrical body portion 52 is normal (YES in step S6), the joint portion is determined to be acceptable (step S7).

[Details of each test]
Specific examples of the penetration error inspection in step S1, the floating inspection of the head portion 51 in step S3, and the expansion degree inspection of the cylindrical body portion 52 in step S5 will be described in detail below with reference to FIGS. 7 to 13. explain.

<Penetration error inspection>
FIG. 7 is a schematic diagram showing an example of an inspection process for a penetration error of the rivet 5. As shown in FIG. FIG. 7 shows a penetration error in which the rivet 5 is not expanded and deformed, penetrates the overlapping portion 30 and the lower end portion 522 contacts the backing material 15 . In this inspection example, it is determined whether or not the lower end portion 522 contacts the backing material 15 based on whether or not a conductive path is formed between the pin member 11 and the backing material 15, that is, a penetration error occurs. detect whether or not Therefore, in this inspection example, conductive members are used as the pin member 11, the rivet 5, and the backing member 15, and non-conductive materials are used as the first member 31 and the second member 32 forming the overlapping portion 30, respectively. It is assumed that

The pin member 11 is electrically connected to the pin conducting portion 25 and can be applied with a DC voltage from a DC power supply provided in the pin conducting portion 25 . On the other hand, an ammeter 26 is incorporated in the ground path of the backing material 15 . The current value measured by the ammeter 26 is transmitted to the contact current detection section 64 of the inspection section 63 (FIG. 3).

When the rivet 5 has a penetration error, the top surface 51H of the rivet 5 contacts the lower end 11T of the pin member 11 and the lower end 522 contacts the backing material 15, as shown in FIG. Therefore, the pin member 11 and the backing material 15 are electrically short-circuited by the rivet 5 . In this state, when a DC voltage is applied to the pin member 11, a current flows through the grounding path of the backing material 15 at the same time as the penetration error occurs. Therefore, if the rivet 5 is driven by the pin member 11 to which a DC voltage is applied, the ammeter 26 will detect a large current when a penetration error occurs.

The contact current detector 64 determines that the lower end 522 of the rivet 5 has contacted the backing material 15 when the current value measured by the ammeter 26 exceeds a predetermined threshold. That is, it is determined that a penetration error has occurred. If no shoot-through error has occurred, the current value measured by the ammeter 26 is equal to zero. Therefore, the predetermined threshold should be set to a value that can distinguish between ON and OFF of the current. According to this inspection example, a feed-through error can be easily and electrically detected by attaching a simple electric device.

FIG. 8 is a schematic diagram showing another example of the inspection process for the penetration error of the rivet 5. FIG. FIG. 8 also shows a state in which a penetration error of the rivet 5 has occurred. In this inspection example, it is detected whether or not the lower end portion 522 of the rivet 5 abuts the backing material 15 based on the motor current of the electric motor that is the driving source of the pin driving portion 21 or the rotation driving portion 23 . The motor current is monitored by a motor current detector 65 .

The rivet 5 is driven into the friction stir portion 4 by the downward movement of the pin member 11 . A motor current corresponding to the downward load of the pin member 11 flows through the electric motor of the pin driving portion 21 . When a penetration error occurs and the lower end 522 abuts against the backing material 15, the descending load increases sharply. As a result, the motor current also rises sharply. The motor current detection unit 65 is given in advance a threshold value of the motor current that serves as a determination criterion for the penetration error. The motor current detector 65 determines that the lower end 522 of the rivet 5 has come into contact with the backing material 15 when the motor current exceeding the threshold is detected.

The rivet 5 may be driven while being rotated around its axis. In this case, engaging portions for engaging the pin member 11 and the rivet 5 are provided on the lower end portion 11T and the top surface 51H, respectively. When the rivet 5 is press-fitted, the rotation driving portion 23 rotates the pin member 11 . At this time, a motor current corresponding to the rotation load of the pin member 11 flows through the electric motor of the rotation driving section 23 .

When the rivet 5 is driven by rotation in this manner, if a penetration error occurs, the rotating lower end portion 522 hits the backing material 15 . Due to this collision, the rotational frictional resistance of the lower end portion 522 increases sharply, and the motor current also rises sharply. The motor current detection section 65 determines that the lower end portion 522 of the rivet 5 has come into contact with the backing material 15 when the motor current of the rotary drive section 23 exceeds the threshold value.

The motor current of the pin drive unit 21 or the rotation drive unit 23 is often monitored for the purpose of controlling the amount of press-fitting of the tool 1 into the overlapped portion 30 during friction stir spot welding. That is, in many cases, the friction stir spot welding apparatus M originally has a functional unit corresponding to the motor current detection unit 65 . According to the inspection example of FIG. 8, the penetration error can be detected using the functional units necessary for the original control of the friction stir spot welding device M.

<Head lift inspection>
FIG. 9 is a schematic diagram showing an example of the floating inspection process of the head portion 51 of the rivet 5. As shown in FIG. FIG. 9 shows an example in which the cylindrical portion 52 of the rivet 5 is not sufficiently press-fitted, and the lower end surface 51B of the head portion 51 is lifted from the upper surface 30U of the overlapping portion 30. As shown in FIG. In contrast, FIG. 10A shows a normal overlapping portion 30 in which the head portion 51 is not lifted. The lower end surface 51B is in contact with the upper surface 30U, and the entire length of the cylinder portion 52 is press-fitted into the friction stir portion 4. As shown in FIG. On the other hand, FIG. 10B shows the state in which the tool 1 is removed from the overlapped portion 30 in which the lift failure occurs in FIG. A gap h2 is formed between the lower end surface 51B and the upper surface 30U.

In this inspection example, the floating of the head portion 51 is detected by performing processing to obtain the interval h2 between the lower end surface 51B and the upper surface 30U. Specifically, the gap h2 is calculated from the lowered position of the pin member 11, which is a press-fitting tool for pushing the rivet 5, and the thickness h1 of the head portion 51. FIG. As described above, the output value of the encoder 24 is used for the calculation.

A first encoder 241 is attached to the electric motor of the pin drive unit 21 . A second encoder 242 is attached to the electric motor of the shoulder drive unit 22 . Output values of the first and

second encoders

241 and 242 are sent to the tool position detection section 66 . In the state shown in FIG. 9, the lower end portion 11T of the pin member 11 is in contact with the top surface 51H of the head portion 51. As shown in FIG. Therefore, the output value of the first encoder 241 becomes information corresponding to the lowered position of the lower end portion 11T, that is, the height position of the top surface 51H. Further, the lower end portion 12T of the shoulder member 12 is in contact with the upper surface 30U of the overlapping portion 30. As shown in FIG. Therefore, the output value of the second encoder 242 becomes information corresponding to the height position of the upper surface 30U. The tool position detection section 66 identifies the height positions of the lower end portion 11T and the upper surface 30U based on these pieces of information, and transmits the position data to the clearance calculation section 67 .

The gap calculator 67 is provided with data of the thickness h1 of the head portion 51, which is thickness information of the head portion 51, in advance. The gap calculator 67 calculates the gap h2, which is the distance between the lower end surface 51B of the head portion 51 and the upper surface 30U, from the height positions of the lower end portion 11T and the upper surface 30U and the head portion thickness h1. The gap calculator 67 determines whether or not the head section 51 has a floating defect based on the calculated gap h2. When it is planned that the entire length of the cylindrical body portion 52 is press-fitted into the friction stir portion 4, the allowable value of the interval h2 is zero or near zero. If the cylinder portion 52 is not expected to be press-fitted over the entire length and the head portion 51 is allowed to float to some extent, the allowable value of the interval h2 is set accordingly.

The height position of the upper surface 30U may be obtained from the output value of the stroke sensor 27. The clamp member 13 clamps the overlapping portion 30 during joining. Therefore, the lower end portion 13T of the clamp member 13 is securely in contact with the upper surface 30U. On the other hand, stroke sensor 27 detects the relative position between shoulder member 12 and clamp member 13 . Therefore, when the origins of the pin member 11 and the shoulder member 12 are aligned, the height difference between the upper surface 30U and the lower end portion 11T is determined from the output value of the first encoder 241 and the output value of the stroke sensor 27. can be found.

A rivet 5 having a smaller diameter for the head portion 51 than the cylinder portion 52 may be used. In this case, the interval h2 is the interval between the lower end of the head portion 51, which is the boundary line between the head portion 51 and the cylindrical body portion 52, and the upper surface 30U. Further, when a press-fitting tool separate from the pin member 11 of the tool 1 is used for pressing the rivet 5, the height position of the top surface 51H of the head portion 51 should be known based on the lowered position of the press-fitting tool. can be done.

In this inspection example, the output values of the first and

second encoders

241 and 242 are used. Generally, for the purpose of controlling the position of the pin member 11, etc., the electric motors of the pin driving section 21 and the shoulder driving section 22 are equipped with encoders as standard equipment. Therefore, according to this inspection example, the floating inspection of the head section 51 can be performed without adding a new measuring device.

<Expansion degree inspection of cylinder>
In this embodiment, by measuring the temperature of the friction stir welded portion where the rivet 5 is driven, a shape estimating means for estimating the degree of expansion of the cylindrical body portion 52 is provided, and the degree of expansion is determined. . That is, it is determined whether or not the cylindrical portion 52 is expanded so that the interlock portion 53 (part of the cylindrical portion) enters the second member 32 around the friction stir portion 4 .

11A and 11B are schematic diagrams showing an example of an inspection process for the degree of expansion of the cylindrical portion 52 of the rivet 5. FIG. FIG. 11 shows an example in which a thermography 281 and the above-described shape estimating section 68 and determining section 69 are used as the shape estimating means. The thermographer 281 is a non-contact thermometer capable of sensing infrared rays emitted from an object and detecting the heat distribution of the object. FIG. 11 shows an example in which the thermography 281 is arranged below the overlapping portion 30 where the rivet 5 is driven. In this example, the thermography 281 measures the two-dimensional temperature distribution on the lower surface side of the overlapping portion 30 .

The thermography 281 can be mounted on the C-shaped frame 16 in parallel with the backing material 15. In this case, after the overlapping portion 30 is unclamped by the clamp member 13 , the thermography 281 is made to face the rivet 5 driving position by moving the robot arm or the like. Of course, the thermography 281 may be held by a separate holding member. Also, if the backing material 15 is made of a material that transmits infrared rays, it may be arranged below the backing material 15 . Furthermore, if the temperature is measured in another process after bonding, the thermography 281 may be arranged above or below the overlapping portion 30 .

The rivet 5 heats up when it is press-fitted into the overlapping portion 30 . Specifically, heat transfer from the friction stir section 4 which is heated by friction stirring, friction heat due to contact with the pin member 11 rotating at high speed, or friction heat due to press-fitting itself are factors of the increase in temperature. . In the case of heat transfer from the friction stir portion 4, since the rivets 5 and the second member 32 have different thermal conductivities, A clear temperature difference occurs. In the case of frictional heat, since the rivet 5 itself generates heat, a temperature difference with the second member 32 also occurs. Therefore, when the temperature is measured by the thermography 281 at the time of forming the friction stir welded portion or immediately after the formation, when the rivet 5 retains a higher temperature than the second member 32, the temperature distribution based on the temperature difference can be clearly detected.

The upper graph in FIG. 11 is a graph showing the temperature gradient TP so that the temperature distribution detected by the thermography 281 matches the cross-sectional shape of the overlapping portion 30 shown. The temperature gradient TP has a sharply rising curve at positions L1 and L2. Here, the positions L1 and L2 correspond to the widest part of the cylindrical body part 52, that is, the interlock part 53, as an example. In the temperature distribution from the lower surface side of the overlapping portion 30 , the interlock portion 53 appears as a thermal boundary between the rivet 5 and the second member 32 .

When the tubular portion 52 is normally expanded, the interlock portion 53 extends radially outward beyond the side peripheral surface 41 of the friction stir portion 4 . Therefore, the positions L1 and L2 of the temperature gradient TP appear radially outside the side peripheral surface 41 that is the outer edge of the friction stir portion 4 that is planned. On the other hand, when the cylindrical body portion 52 is in an unstable expansion state, the positions L1 and L2 appear at substantially the same positions as the side peripheral surface 41 or radially inward of the side peripheral surface 41 .

The graph illustrated in FIG. 11 assumes that the positions L1 and L2 correspond to the interlock portion 53. In practice, the positions L1 and L2 and the position of the interlock portion 53 may vary depending on the thermal conductivity of the constituent materials of the second member 32 and the rivet 5, the thickness of the second member 32, the degree of press-fitting of the rivet 5, and the like. Misalignment may occur. In this case, the positions L1 and L2 and the interlock portion 53 can be associated with each other by previously determining the amount of deviation through experiments or the like and setting a correction value.

The shape estimator 68 estimates the expanded shape of the tubular body 52 based on the temperature distribution of the overlapped portion 30 after the rivet 5 is press-fit, which is measured by the thermography 281 . For example, the shape estimator 68 identifies the positions L1 and L2 by detecting points where the rate of change of the temperature gradient TP exceeds a predetermined threshold. As described above, the determination unit 69 determines whether or not the degree of expansion of the tubular body 52 is normal by comparing the expansion shape estimated by the shape estimation unit 68 with a reference template or the like. According to this inspection example, the difference in thermal conductivity between the rivet 5 and the second member 32 can be used to inspect the expansion degree of the cylindrical body portion 52 nondestructively.

The above example shows an example of using the thermography 281, which is a non-contact temperature measuring instrument. Next, an example using a contact-type temperature measuring instrument will be shown. 12A and 12B are schematic diagrams showing another example of the inspection process for the expansion degree of the cylindrical body portion 52. FIG. A thermocouple 282 is incorporated in the backing material 15 as a contact-type temperature measuring device. The lower surface of the overlapping portion 30 contacts the backing material 15 at the time of joining. That is, the heat of the overlapping portion 30 is transferred to the backing material 15 as it is. Therefore, by embedding the thermocouple 282 in the backing material 15, the temperature state of the lower surface of the overlapping portion 30 can be detected.

The temperature sensing portion of the thermocouple 282 is located near the surface of the backing material 15 and vertically opposed to the assumed position of the interlock portion 53 when the cylindrical body portion 52 is normally expanded. placed. The thermocouple 282 detects a high temperature when the tubular portion 52 is normally unfolded. This is because the thermocouple 282 faces the interlock portion 53 and detects the heat generated from the interlock portion 53 . On the other hand, when the cylindrical body portion 52 has an expansion failure, the thermocouple 282 detects a relatively low temperature. This is because the thermocouple 282 does not face the interlock portion 53 and detects the temperature of the second member 32 . Thus, whether or not the interlock portion 53 is present at a predetermined position in the overlapping portion 30 can be known based on the temperature detected by the thermocouple 282 .

A large number of thermocouples 282 may be incorporated in the backing material 15 to detect the temperature distribution on the lower surface of the overlapping portion 30. In this case, it is desirable to arrange multiple thermocouples 282 on the backing material 15 in a concentric circular pattern. Alternatively, the thermocouple 282 may be incorporated in a temperature detecting member separate from the backing material 15 and brought into contact with the lower surface of the overlapping portion 30 immediately after the friction stir weld is formed. Furthermore, other contact-type temperature measurement elements than the thermocouple 282 may be used.

During or immediately after the formation of the friction stir welded portion, the inspection example of FIG. 11 or 12 can be performed based on the temperature difference between the rivet 5 and the second member 32 . However, when the temperature of the rivet 5 becomes room temperature with the lapse of time from the formation of the joint, the above inspection example cannot be applied. For example, if the step of forming the friction stir welded portion and the step of inspecting the friction stir welded portion are performed in separate steps with a time interval between them, the temperature difference disappears, and the temperature distribution does not appear in the overlapping portion 30 . In such a case, the rivet 5 is externally heated before inspection.

FIG. 13 is a cross-sectional view showing how the rivet 5 is externally heated. FIG. 13 shows a state in which heat H is applied from the heat source 283 to the head portion 51 of the rivet 5 . As the heat source 283, for example, a contact heat source using a heating rod or the like, a non-contact heat source generating hot air, or the like can be used. Alternatively, the head portion 51 may be held by a pair of electrodes, and the rivet itself may be resistively heated, or when the rivet 5 is a magnetic material, an IH heating source may be used. Furthermore, the heat H may be indirectly applied to the rivet 5 from the lower surface side of the overlapping portion 30 via the second member 32 . By applying heat H from the heating source 283 to the rivet 5 and measuring the temperature with the thermography 281 or the thermocouple 282, the temperature distribution of the lower surface of the overlapping portion 30 can be reliably detected.

[Modification]
Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above embodiments. For example, the following modified embodiments can be taken.

(1) In the above-described embodiment, three kinds of inspections are performed: inspection for penetration error of the rivet 5 (step S1 in FIG. 6), inspection for floating of the head portion 51 (step S3), and inspection for degree of expansion of the cylinder portion 52 (step S5). An example of doing Alternatively, one or both of the floating inspection and the expansion degree inspection may be omitted. Further, the execution order of the three types of inspection is arbitrary, and the floating inspection or the expansion degree inspection may be executed first.

(2) In the above embodiment, the penetration error inspection of the rivet 5 is performed by detecting the energization between the pin member 11 and the backing material 15 (Fig. 7) or by detecting the motor current (Fig. 8). The penetration error is detected by a sound wave sensor that detects a collision sound when the lower end portion 522 of the rivet 5 collides with the backing material 15, a vibration sensor that detects vibration or pressure fluctuation of the backing material 15 at the time of collision, a load cell, or the like. can also be detected.

(3) In the above embodiment, the floating of the head portion 51 is detected based on the encoder value of the electric motor that serves as the driving source of the pin driving portion 21 and the shoulder driving portion 22 (FIG. 9). Instead of this, floating of the head portion 51 may be detected by image processing. For example, after the rivet 5 is driven into the overlapping portion 30, a perspective image of the head portion 51 is captured by a camera arranged on the upper surface 30U side. Since there is a difference in image density between the top surface 51H and the side peripheral surface of the head portion 51, both can be distinguished. When the head portion 51 is floating, the area of the side peripheral surface increases in the captured perspective image. Therefore, by obtaining the area ratio between the top surface 51H and the side peripheral surface on the image, the floating of the head portion 51 can be found.

(4) In the above embodiment, an example was shown in which the tool 1 for double-acting friction stir spot welding is used as the tool forming the friction stir part 4 . Alternatively, a friction stir line welding tool, a single-acting friction stir point welding tool, or another friction stir welding tool may be used as the tool. Further, when using the tool 1 for double-acting friction stir spot welding, friction stir may be performed in the pin leading process.

As described above, the friction stir weld inspection method according to the present disclosure includes the step of detecting whether or not the lower end portion 522 of the rivet 5 has come into contact with the backing material 15 . Therefore, it can be detected that the rivet 5 penetrates the friction stir portion 4 and the second member 32 and abuts against the backing material 15 . In other words, the rivet 5 penetrates the friction stir portion 4 without deforming as planned, that is, deforming to form the interlock portion 53 with respect to the second member 32 around the friction stir portion 4. Poor enforcement can be detected. Therefore, it is possible to accurately inspect the friction stir welded portion where the rivet 5 is driven without penetrating the overlapping portion 30 .

[Inventions included in the above embodiments]
The embodiments described above further include the following disclosures.

An inspection method for a friction stir weld according to one embodiment includes: an overlapping portion including a first member and a second member arranged in a lower layer of the first member; In a friction stir weld formed by press-fitting a friction stir tool from the side of the first member in a supported state to form a friction stir portion and pressing a fastening body into the friction stir portion from the side of the first member , a friction stir welding part in which a fastening body comprising a head portion and a cylindrical body portion connected to the head portion is used as the fastening body, and a predetermined length of the cylindrical body portion is press-fitted into the overlapping portion. In the inspection method, the distance between the lower end of the head portion and the upper surface of the first member is obtained.

A joining device according to one embodiment is a joining device for joining an overlapped portion including a first member and a second member arranged in a lower layer of the first member, and a friction stir tool that is press-fitted into a portion to form a friction stir portion in the overlapping portion; a head portion; and a cylindrical body portion connected to the head portion; A press-fitting tool for press-fitting a fastening body to be press-fitted into the friction stir portion from the first member side, a backing material for supporting the overlapping portion from the second member side, a lower end of the head portion and the second and measuring means for determining the distance from the upper surface of the member.

According to the above inspection method or joining apparatus, it is possible to inspect whether or not the distance between the lower end of the head portion of the fastening body and the upper surface of the first member is appropriate based on the measurement result of the measuring means. In other words, by measuring the distance, it is possible to inspect whether or not the cylindrical body portion of the fastening body is press-fitted into the friction stir portion by the specified press-fitting depth. For example, when the press-fitting depth is insufficient due to buckling of the cylindrical body portion, there is a gap of a predetermined value or more between the lower end of the head portion and the upper surface of the first member. will open. More specifically, if the lower end of the head portion and the upper surface of the first member are expected to come into close contact with each other when a normal fastening body is press-fitted, if insufficient press-fitting occurs, there will be a gap between the two. will be detected. Therefore, it is possible to accurately inspect the friction stir welded portion in which the fastening body is driven without penetrating the overlapping portion.

A method for inspecting a friction stir welded portion according to another embodiment includes: an overlapping portion including a first member and a second member arranged in a lower layer of the first member; In a friction stir weld formed by press-fitting a friction stir tool from the side of the first member in a supported state to form a friction stir portion and pressing a fastening body into the friction stir portion from the side of the first member , a method for inspecting a friction stir weld in which a fastening body including a cylindrical body part that deforms so that at least a part of it enters the second member around the friction stir part is used as the fastening body, The degree of deformation of the cylinder is detected by measuring the temperature of the agitated joint.

A joining device according to one embodiment is a joining device for joining an overlapped portion including a first member and a second member arranged in a lower layer of the first member, and a friction stir tool that is press-fitted into a portion to form a friction stir portion in the overlapping portion; By measuring the temperature of a press-fitting tool that press-fits into the friction stir portion from the first member side, a backing material that supports the overlapping portion from the second member side, and the friction stir weld portion, the cylindrical body and shape estimation means for estimating the degree of deformation of the part.

According to the above inspection method or welding apparatus, by measuring the temperature of the friction stir weld, based on the temperature difference between the first member and the second member and the fastening body, Shape can be estimated. Then, based on the estimated degree of deformation of the tubular portion, it is possible to inspect whether or not the deformed state of the tubular portion is appropriate. In other words, it is possible to inspect whether or not the cylindrical portion is deformed normally and part of the cylindrical portion enters the second member around the friction stir portion. If the deformation of the cylindrical body portion is insufficient, part of the cylindrical body portion cannot enter the second member existing around the friction stir portion, and a sufficient interlock effect cannot be exhibited. Therefore, it is possible to accurately inspect the friction stir welded portion in which the fastening body is driven without penetrating the overlapping portion.

Claims

A friction stir tool is press-fitted from the side of the first member into the overlapping portion including the first member and the second member arranged in the lower layer of the first member while the second member is supported by a backing material. A method for inspecting a friction stir weld formed by forming a friction stir portion by pressing a fastening body into the friction stir portion from the side of the first member,
detecting whether a portion of the fastener abuts the backing material;
Inspection method for friction stir welds.
In the method for inspecting a friction stir weld according to claim 1,
Using conductive members as the friction stir tool, the fastening body, and the backing material, and using non-conductive materials as the first member and the second member,
An inspection of a friction stir weld that determines that a portion of the fastener abuts the backing material when the current flowing between the friction stir tool and the backing material exceeds a predetermined threshold. Method.
In the method for inspecting a friction stir weld according to claim 1,
Using an electric motor as a drive source for the friction stir tool,
A method for inspecting a friction stir weld, wherein it is determined that a portion of the fastening body has contacted the backing material when a motor current driving the electric motor exceeds a predetermined threshold.
In the method for inspecting a friction stir weld according to claim 1,
As the fastening body, a fastening body comprising a head portion and a cylindrical body portion connected to the head portion is used, and a predetermined length of the cylindrical body portion is press-fitted into the overlapping portion,
A method for inspecting a friction stir welded part, which determines the distance between the lower end of the head part and the upper surface of the first member.
In the method for inspecting a friction stir weld according to claim 4,
press-fitting the fastening body into the overlapping portion by pushing the fastening body down by lowering a press-fitting tool;
A method for inspecting a friction stir welded portion, wherein the interval between the lower end of the head portion and the upper surface of the first member is obtained from the lowered position of the press-fitting tool and the thickness of the head portion.
In the method for inspecting a friction stir weld according to claim 5,
Using the friction stir tool as the press fitting tool,
A method for inspecting a friction stir weld, comprising calculating a lowered position of the friction stir tool based on an output value of an encoder attached to an electric motor that drives the friction stir tool.
In the method for inspecting a friction stir weld according to claim 1,
The fastening body includes a cylindrical body portion that deforms so that at least a portion of it enters the second member around the friction stir portion,
A method for inspecting a friction stir weld, comprising the step of detecting the degree of deformation of the tubular body by measuring the temperature of the friction stir weld.
In the method for inspecting a friction stir weld according to claim 7,
measuring the temperature distribution of the friction stir welding portion after the fastening body is press-fitted, and estimating the deformation shape of the cylindrical body portion based on the temperature distribution, thereby detecting the degree of deformation of the cylindrical body portion; Method for inspecting stir joints.
In the method for inspecting a friction stir weld according to claim 7,
A method for inspecting a friction stir weld, wherein the temperature of the friction stir weld is measured by a thermometer incorporated in the backing material.
In the method for inspecting a friction stir weld according to any one of claims 7 to 9,
A method for inspecting a friction stir weld, comprising applying heat to the fastening body to measure the temperature of the friction stir weld after forming the friction stir weld.
In the method for inspecting a friction stir weld according to any one of claims 7 to 9,
During or immediately after the formation of the friction stir welded portion, the temperature of the friction stir welded portion is measured at a stage where the fastening body retains a higher heat than the second member. Inspection methods.
A joining device for joining an overlapping portion including a first member and a second member arranged in a lower layer of the first member,
a friction stir tool that is press-fitted from the first member into the overlapping portion to form a friction stir portion in the overlapping portion;
a press-fitting tool for press-fitting a fastening body from the side of the first member into the friction stir portion;
a backing material that supports the overlapping portion from the second member side;
detection means for detecting whether or not a portion of the fastening body contacts the backing material;
A splicing device comprising:
The joining apparatus according to claim 12,
As a tool that serves as the friction stir tool and the press-fitting tool,
a cylindrical pin member that rotates about an axis and can move back and forth in the direction of the axis;
a cylindrical shoulder member positioned so as to cover the outer periphery of the pin member, rotating about the same axis as the pin member and capable of advancing and retreating in the axial direction. a joining tool; and
a control unit for the tool;
The control unit
When forming the friction stir portion, the pin member or the shoulder member is press-fitted into the overlapping portion to perform a friction stir operation,
The joining device, wherein when press-fitting the fastening body, the pin member or the shoulder member is lowered so as to push the fastening body into the overlapping portion.
The joining apparatus according to claim 12 or 13,
As the fastening body, a fastening body comprising a head portion and a cylindrical body portion connected to the head portion, wherein a predetermined length of the cylindrical body portion is press-fitted into the overlapping portion is used,
A joining apparatus further comprising measuring means for determining a gap between the lower end of the head portion and the upper surface of the first member.
The joining apparatus according to claim 12 or 13,
The fastening body includes a cylindrical body part that deforms so as to partially enter the second member around the friction stir part,
The welding apparatus further comprises a shape estimating means for estimating the degree of deformation of the cylindrical body portion by measuring the temperature of the friction stir welding portion.