Guide block and friction stir welding method

Abstract

To provide a guide block and a friction stirring and joining method which can appropriately press a pair of joined members forming an inner corner part even when the surfaces of the joined members are curved surfaces.SOLUTION: A guide block 20 has a guide hole 21 rotatably holding a stirring pin 11, a first contact surface 22 which is brought into contact with one (surface 8 of a joint 6) of a pair of joined members, and a second contact surface 23 which is brought into contact with the other (end face 7 of a cylindrical body 5) of the pair of joined members, wherein the first contact surface 22 is a curved surface (cylindrical surface) which can be brought into close contact with the surface 8 of the one joined member (joint 6).SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a guide block for inner corner friction stir welding and a friction stir welding method. [Background technology]

[0002] When performing friction stir welding on a pair of workpieces that form an inner corner, a rotary tool for inner corner welding is used, in which a triangular prism-shaped base block is attached to a stirring pin (Patent Document 1). The base block rotatably holds and guides the stirring pin, and the pair of inclined surfaces abut against the surfaces of the pair of workpieces, thereby pressing down on the workpieces and preventing them from lifting up or vibrating. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-79031 Summary of the Invention [Problem to be solved by the invention]

[0004] The rotary tool for joining inner corners in Patent Document 1 described above has a pair of inclined surfaces formed on the base block that are flat. If the surfaces of the pair of workpieces to be joined are both flat, the surfaces come into surface contact with each other, thereby pressing down on the workpieces to prevent them from lifting up or vibrating. However, if the surface of even one of the pair of workpieces is not flat, line contact or point contact will occur, and it may not be possible to sufficiently press down on the workpieces to prevent lifting or vibration.

[0005] For example, when joining a cylindrical joint to the inside of the end of a cylindrical body, the end face of the outer cylinder is flat, while the surface of the inner joint is cylindrical. When performing friction stir welding on an inner corner of a ring-shaped joint formed by such a flat and cylindrical surface, if a rotary tool for joining inner corners with a pair of flat inclined surfaces is used, the flat inclined surfaces will not be able to make surface contact with the cylindrical joint surface, but will instead make line contact. As a result, the base block becomes unstable and can rotate around this contact line, which can prevent the workpieces from lifting or vibrating.

[0006] An object of the present invention is to provide a guide block and a friction stir welding method that can hold down a pair of workpieces to suppress lifting and vibration even if the surfaces of the workpieces that form the inner corner are curved. [Means for solving the problem]

[0007] The guide block of the present invention is a guide block that is attached to a stirring pin that performs friction stir welding on an inner corner formed by a pair of workpieces, at least one of which has a curved surface, and is characterized in that it has a guide hole that rotatably holds the stirring pin, a first abutment surface that abuts against one of the pair of workpieces, and a second abutment surface that abuts against the other of the pair of workpieces, and at least the first abutment surface is a curved surface that can come into close contact with the surface of one of the workpieces, which has a curved surface.

[0008] In the present invention, the stirring pin and the guide block are brought close to the inner corners of the pair of workpieces with the stirring pin inserted through the guide hole, and the first and second contact surfaces are brought into contact with the surfaces of the pair of workpieces to hold them down, while the rotating stirring pin friction stir welds the intersecting portion of the pair of workpieces. Here, in the present invention, even if one surface of a pair of workpieces to be joined is curved, the first abutment surface is in close surface contact with this curved surface, thereby holding down the workpieces to suppress lifting and vibration. In addition, if both surfaces of a pair of workpieces are curved, the first abutment surface and the second abutment surface can be made curved to correspond to the surfaces of the pair of workpieces, thereby pressing down on the workpieces and suppressing lifting and vibration.

[0009] In the guide block of the present invention, it is preferable that the first abutment surface and the second abutment surface intersect with each other at a predetermined intersection angle, and the guide hole passes through the intersection portion between the first abutment surface and the second abutment surface. The intersection angle between the first and second contact surfaces may be the angle formed by the first and second contact surfaces in an imaginary plane perpendicular to each of the first and second contact surfaces, or may be the angle formed by the first and second contact surfaces in an imaginary plane perpendicular to the joining line along which the first and second contact surfaces are joined. In this invention, the stirring pin inserted into the guide hole can be held facing the intersection of the first abutment surface and the second abutment surface, i.e., the intersection of the pair of workpieces, and the stirring pin can be guided in a state appropriate for friction stir welding while holding down the pair of workpieces to suppress lifting and vibration.

[0010] In the guide block of the present invention, it is preferable that the first contact surface is a cylindrical surface and the second contact surface is a flat surface. In this invention, for example, when joining a cylindrical joint to the inside of the end of a cylindrical body, the end face of the outer cylindrical body and the second abutment surface can be in close contact with each other on their flat surfaces, and the surface of the inner joint and the first abutment surface can be in close contact with each other on their cylindrical surfaces. This allows the guide block to be stably held on the end face of the outer cylindrical body and the surface of the inner joint, and can hold down the pair of workpieces to suppress lifting and vibration.

[0011] In the guide block of the present invention, it is preferable that the first contact surface and the second contact surface are both conical surfaces. In the present invention, for example, when joining the ends of cylindrical bodies having inclined surfaces that are beveled at the outer periphery, each inclined surface can be in close contact with the first and second conical abutment surfaces, so that the guide block is stably held by the inclined surfaces of the pair of cylindrical bodies and can press down on the pair of workpieces to prevent them from lifting up or vibrating.

[0012] The friction stir welding method of the present invention is characterized in that, when friction stir welding an inner corner formed by a pair of workpieces, at least one of which has a curved surface, a guide block is used that has a guide hole for rotatably holding a stir pin, a first abutment surface that abuts against one of the pair of workpieces, and a second abutment surface that abuts against the other of the pair of workpieces, wherein at least the first abutment surface is a curved surface that can come into close contact with the surface of one of the workpieces, the surface of which is a curved surface. According to the friction stir welding method of the present invention, the same effects as those described above for the guide block of the present invention can be obtained. [Effects of the Invention]

[0013] According to the present invention, a guide block and a friction stir welding method are provided that can hold down a pair of workpieces to suppress lifting and vibration even when the surfaces of the workpieces forming the inner corner are curved. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a perspective view showing friction stir welding in a first embodiment of the present invention. [Figure 2] FIG. 3 is a plan view of the guide block according to the first embodiment. [Figure 3] FIG. 3 is a side view of the guide block according to the first embodiment. [Figure 4] FIG. 2 is a front view of the guide block according to the first embodiment. [Figure 5] FIG. 10 is a perspective view showing friction stir welding in a second embodiment of the present invention. [Figure 6] FIG. 10 is a plan view of the guide block of the second embodiment. [Figure 7] FIG. 10 is a side view of the guide block of the second embodiment. [Figure 8] FIG. 10 is a front view of the guide block according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. [First embodiment] 1 to 4 show a first embodiment of the present invention. In FIG. 1, in this embodiment, friction stir welding is performed on an inner corner 4 of a workpiece 3 using a rotating tool 10 for inner corner welding attached to a spindle 2 of a machine tool 1. The workpiece 3 to be joined consists of a cylindrical body 5 and a cylindrical joint 6 joined to the inside of its end, and the end surface 7 of the cylindrical body 5 is flat, but the surface 8 of the joint 6 is cylindrical. In this embodiment, the joint 6, whose surface 8 is a cylindrical surface, corresponds to one of the members to be joined in the present invention, and the cylindrical body 5, whose end surface 7 is a flat surface, corresponds to the other member to be joined in the present invention. The inner corner 4 is formed between the end surface 7 and the surface 8. The angle between the end surface 7 and the surface 8 is 90 degrees.

[0016] 2, 3 and 4, the inner corner welding rotary tool 10 is configured by attaching a guide block 20 to a stirring pin 11 for friction stir welding. The guide block 20 is a block-shaped member formed by cutting a metal material or the like, and has a guide hole 21 that rotatably holds the stirring pin 11, a first abutment surface 22 that abuts against the surface 8 of the joint 6 (one of the members to be joined), and a second abutment surface 23 that abuts against the end surface 7 of the cylindrical body 5 (the other of the members to be joined).

[0017] Guide hole 21 has a bearing (not shown) inside, which can rotatably hold stirring pin 11. The bearing of guide hole 21 includes a thrust bearing, and stirring pin 11 is inserted into guide hole 21 from above in the figure, and its advancement is restricted in the state shown in Figures 2 and 3, and it is maintained rotatably in a state where it protrudes from guide block 20 by a predetermined amount.

[0018] The first abutment surface 22 is formed by cutting out one of the long sides of the guide block 20 on the lower side in the figure at an angle of 45 degrees with respect to the lower surface in the figure, and into a cylindrical shape. The cylindrical surface of the first abutment surface 22 has a curvature that allows it to come into close contact with the surface 8 of the joint 6. The second abutment surface 23 is formed by cutting out the other long side of the guide block 20 on the lower side in the figure at an angle of 45 degrees to the lower surface in the figure. The second abutment surface 23 is at an angle of 90 degrees to the first abutment surface 22, and can be in close contact with the end surface 7 of the cylindrical body 5 while the first abutment surface 22 is in close contact with the surface 8 of the joint 6.

[0019] If the joint 6 is cylindrical, the generatrix of the surface 8 is parallel to the central axis of the joint 6. The end surface 7 of the cylindrical body 5 is usually a plane perpendicular to the central axis of the cylindrical body 5. The angle between the surface 8 of the joint 6 and the end surface 7 of the cylindrical body 5 is usually 90 degrees. Therefore, the angle between the second abutment surface 23 and the first abutment surface 22 is also 90 degrees. By setting this angle, the first abutment surface 22 can be in close contact with the end surface 7 of the cylindrical body 5 while in close contact with the surface 8 of the joint 6. The angles formed by the guide block 20 and the first and second contact surfaces 22, 23 are 45 degrees each, totaling 90 degrees, so that the angles formed by the guide block 20 and the surface 8 of the joint 6 and the end surface 7 of the cylindrical body 5 are equal. These angles may be, for example, 40 degrees and 50 degrees, and can be changed taking into account the angle of the central axis 21C of the guide hole 21, which will be described later, i.e., the angle of the stirring pin 11 relative to the surface 8 of the joint 6 and the end surface 7 of the cylindrical body 5.

[0020] If the angle formed between the surface 8 of the joint 6 and the end face 7 of the cylindrical body 5 is not 90 degrees, the angle formed between the second abutment surface 23 and the first abutment surface 22 can be changed to match that angle. In such a case, the angles formed between the guide block 20 and the first abutment surface 22 and the second abutment surface 23 can also be changed as appropriate. For example, if the angle formed between the surface 8 of the joint 6 and the end face 7 of the cylindrical body 5 is 80 degrees, the angles may be 40 degrees each, for a total of 80 degrees.

[0021] 2 and 4, the intersection of the first contact surface 22 and the second contact surface 23 forms an arc-shaped ridgeline 24. The pointed ends of the ridgeline 24 are cut away to form flat portions 25 for safety reasons. As shown in Figures 3 and 4, the guide hole 21 is formed so that the central axis 21C passes through the ridge line 24, and the stirring pin 11 held in the guide hole 21 is positioned so that it is approximately half-immersed in the end face 7 of the cylindrical body 5 and half-immersed in the surface 8 of the joint 6. The central axis 21C of the guide hole 21 is angled at 45 degrees with respect to the first contact surface 22 and the second contact surface 23, respectively.

[0022] In this embodiment, friction stir welding is performed in the following procedure. First, the stirring pin 11 is inserted into the guide hole 21 to form the rotary tool 10 for joining inner corners, which is then attached to the spindle 2. The machine tool 1 is then operated to bring the stirring pin 11 and guide block 20 close to the inner corner 4 of the workpiece 3, i.e., the joint portion sandwiched between the end face 7 of the cylindrical body 5 and the surface 8 of the joint 6. Next, while rotating the main shaft 2 to rotate the stirring pin 11, the first abutment surface 22 and the second abutment surface 23 of the guide block 20 are brought into contact with the surface 8 and the end face 7, respectively, and the stirring pin 11 held in the guide hole 21 is pressed against the joint portion between the surface 8 and the end face 7, thereby starting friction stir welding of the cylindrical body 5 and the joint 6. Next, while friction stirring the cylindrical body 5 and the joint 6 with the stirring pin 11, the stirring pin 11 is moved along the joint between the surface 8 and the end face 7, whereby the joint between the surface 8 and the end face 7 is sequentially friction stir welded.

[0023] According to this embodiment, the following effects can be obtained. In this embodiment, the first abutment surface 22 and the second abutment surface 23 of the guide block 20 move while being in close contact with the surface 8 and the end face 7, respectively, so that the stirring pin 11 held in the guide hole 21 is always maintained at a constant depth and angle relative to the joint with the surface 8 and the end face 7, and further presses down on the members to be joined (the surface 8 of the joint 6 and the end face 7 of the cylindrical body 5), suppressing lifting and vibration, thereby performing stable friction stir welding. In other words, in this embodiment, even if one surface (surface 8) of a pair of joined members (joint 6) is a curved surface (cylindrical surface), the first abutment surface 22 is in close surface contact with this curved surface, so that the guide block 20 can press and stabilize the joined members (surface 8 of joint 6 and end surface 7 of cylindrical body 5).

[0024] In this embodiment, the first abutment surface 22 and the second abutment surface 23 intersect with each other at 90 degrees (45 degrees + 45 degrees), and the guide hole 21 penetrates the ridge line 24 at the intersection between the first abutment surface 22 and the second abutment surface 23. Therefore, the stirring pin 11 inserted into the guide hole 21 can be held toward the ridge 24 of the intersection between the first abutment surface 22 and the second abutment surface 23, that is, the intersection of a pair of workpieces (the end face 7 of the cylindrical body 5 and the surface 8 of the joint 6), and the stirring pin 11 held in the guide hole 21 can be guided so that it is approximately half-immersed in the end face 7 of the cylindrical body 5 and the surface 8 of the joint 6, that is, in a state suitable for friction stir welding.

[0025] Second Embodiment A second embodiment of the present invention is shown in Figures 5 to 8. In the first embodiment described above, the pair of workpieces to be friction stir welded are the cylindrical body 5 and joint 6 of the workpiece 3, the end face 7 of the cylindrical body 5 is a flat surface, and the surface 8 of the joint 6 is a cylindrical surface. For this reason, the rotating tool 10 for inner corner welding has the first abutment surface 22 as a cylindrical surface and the second abutment surface 23 as a flat surface so that the inner corner 4 can come into close contact with the end face 7, which is a flat surface, and the surface 8, which is a cylindrical surface.

[0026] 5, the workpieces 3A to be joined are cylindrical bodies 5A and 6A of the same diameter, and the edges of each are chamfered at a 45-degree angle to form conical inclined surfaces 7A and 8A, which form the inner corner 4A. In the inner corner joining rotary tool 10A, a guide block 30 corresponding to the pair of inclined surfaces 7A and 8A is attached to a stirring pin 11 for friction stir welding.

[0027] As shown in Figures 6, 7, and 8, the guide block 30 is a block-shaped member formed by cutting a metal material or the like, and has a guide hole 31 that rotatably holds the stirring pin 11, a first abutment surface 32 that abuts against the inclined surface 8A of the cylindrical body 6A (one of the members to be joined), and a second abutment surface 33 that abuts against the inclined surface 7A of the cylindrical body 5A (the other member to be joined).

[0028] The guide hole 31 is similar to the guide hole 21 of the first embodiment described above, so a duplicated description will be omitted.

[0029] The first abutment surface 32 is formed by cutting out one of the long sides of the guide block 30 on the lower side in the figure at an angle of 45 degrees with respect to the lower surface in the figure, and in the shape of a cone. The cone surface of the first abutment surface 32 has a curvature that allows it to come into close contact with the inclined surface 8A of the cylindrical body 6A. The second abutment surface 33 is formed by cutting out a conical surface at an angle of 45 degrees from the lower surface of the guide block 30. The conical surface of the second abutment surface 33 has a curvature that allows it to come into close contact with the inclined surface 7A of the cylindrical body 5A.

[0030] The inclined surface 7A of the cylindrical body 5A and the inclined surface 8A of the cylindrical body 6A can be the same curved surface, in which case the first contact surface 32 and the second contact surface 33 are plane symmetrical. As shown in Fig. 6, the intersection of the first abutment surface 32 and the second abutment surface 33 forms an arc-shaped ridgeline 34. However, the first abutment surface 32 and the second abutment surface 33 are plane symmetrical, and the ridgeline 34 appears as a straight line in Fig. 8. The pointed ends of the ridgeline 34 are cut away to form flat portions 35 for safety reasons.

[0031] As shown in Figures 7 and 8, the guide hole 31 is formed so that the central axis 31C passes through the ridge line 34, and the stirring pin 11 held in the guide hole 31 is positioned so that approximately half of it is immersed in the inclined surfaces 7A and 8A of the cylindrical bodies 5A and 6A. The central axis 31C of the guide hole 31 is angled at 45 degrees with respect to the first contact surface 32 and the second contact surface 33, respectively.

[0032] In this embodiment, friction stir welding is performed in the same procedure as in the first embodiment. That is, the stirring pin 11 is inserted into the guide hole 31 to form a rotary tool 10A for joining inner corners, which is then attached to the spindle 2, and the machine tool 1 is operated to bring the stirring pin 11 and guide block 30 close to the inner corner portion 4A of the workpiece 3A, i.e., the joint portion sandwiched between the inclined surface 7A of the cylindrical body 5A and the inclined surface 8A of the cylindrical body 6A. Then, while rotating the main shaft 2 to rotate the stirring pin 11, the first abutment surface 32 and the second abutment surface 33 of the guide block 30 are brought into contact with the inclined surfaces 7A and 8A, respectively, and the stirring pin 11 held in the guide hole 31 is pressed against the joint portion of the inclined surfaces 7A and 8A, and while friction stirring is performed with the stirring pin 11, the stirring pin 11 is moved along the joint of the inclined surfaces 7A and 8A, whereby the joint of the inclined surfaces 7A and 8A is sequentially friction stir welded.

[0033] According to this embodiment, the following effects can be obtained. In this embodiment, the first abutment surface 32 and the second abutment surface 33 of the guide block 30 move while being in close contact with the inclined surfaces 7A and 8A, respectively, so that the stirring pin 11 held in the guide hole 31 is always maintained at a constant depth and angle relative to the joint of the inclined surfaces 7A and 8A, thereby performing stable friction stir welding. In other words, in this embodiment, even if the surfaces (inclined surfaces 7A, 8A) of a pair of workpieces (cylindrical bodies 5A, 6A) are both curved (conical) surfaces, the first abutment surface 32 and the second abutment surface 33 are in close surface contact with these curved surfaces, so that the guide block 30 can press and stabilize the surfaces (inclined surfaces 7A, 8A) of the workpieces (cylindrical bodies 5A, 6A).

[0034] In this embodiment, as in the first embodiment, the guide hole 31 penetrates the ridge 34 at the intersection of the first abutment surface 32 and the second abutment surface 33, and the stirring pin 11 inserted into the guide hole 31 can be guided so that it is approximately half-immersed in each of the pair of workpieces (the inclined surfaces 7A and 8A of the cylindrical bodies 5A and 6A), that is, in a state appropriate for friction stir welding.

[0035] Other Embodiments The present invention is not limited to the above-described embodiment, and includes modifications within the scope of achieving the object of the present invention. In the above embodiment, the first abutment surfaces 22, 32 and the second abutment surfaces 23, 33 were each continuous curved surfaces (cylindrical or conical surfaces) or flat surfaces, but the surfaces of the first abutment surfaces 22, 32 and the second abutment surfaces 23, 33 are not limited to continuous surfaces. For example, a large number of protrusions and recesses may be formed on the first contact surface 22, 32 or the second contact surface 23, 33, and the tip of each protrusion may be a curved or flat surface along the same imaginary cylindrical or conical surface, as long as the tip surface of each protrusion is simultaneously in close contact with the surface of the workpiece to be joined, allowing the guide blocks 20, 30 to press and stabilize the surface of the workpiece to be joined.

[0036] In each of the above-described embodiments, the guide blocks 20 and 30 may be provided with a coolant passage therein for dissipating heat generated by friction stir welding. In each of the above-described embodiments, the guide holes 21, 31 of the guide blocks 20, 30 may have a detachable divided structure for the bearings or support members that come into contact with the stirring pin 11, and may be replaceable as appropriate. [Industrial Applicability]

[0037] The present invention can be used as a guide block for inner corner friction stir welding and as a friction stir welding method. [Explanation of symbols]

[0038] 1...machine tool, 2...spindle, 3,3A...workpiece, 4,4A...inner corner portion, 5,5A...cylindrical body which is the other of a pair of members to be welded, 6...joint which is one of the pair of members to be welded, 6A...cylindrical body which is one of the pair of members to be welded, 7...end face which is the surface of the other of the pair of members to be welded, 7A...inclined surface of the other of the pair of members to be welded, 8...surface of one of the pair of members to be welded, 8A...inclined surface which is the surface of one of the pair of members to be welded, 10,10A...rotary tool for joining inner corners, 11...stirring pin, 20,30...guide block, 21,31...guide hole, 21C,31C...central axis, 22...first abutment surface (cylindrical surface), 23...second abutment surface (flat surface), 24,34...ridge line, 25,35...flat portion, 32...first abutment surface (conical surface), 33...second abutment surface (conical surface).

Claims

1. A guide block that guides a stirring pin that performs friction stir welding on an inner corner formed by a pair of workpieces, at least one of whose surfaces is a curved surface, a guide hole that rotatably holds the stirring pin, a first contact surface that contacts one of the pair of workpieces, a second contact surface that contacts the other of the pair of workpieces, and flat portions formed on both ends of a ridge line at an intersection between the first contact surface and the second contact surface, A guide block, wherein at least the first contact surface is a curved surface that can come into close contact with the surface of one of the workpieces, the surface of which is a curved surface.

2. 2. The guide block according to claim 1, the first contact surface and the second contact surface intersect with each other at a predetermined intersecting angle, The guide block is characterized in that the guide hole penetrates an intersection portion between the first contact surface and the second contact surface.

3. The guide block according to claim 1 or 2, The guide block according to claim 1, wherein the first contact surface is a cylindrical surface and the second contact surface is a flat surface.

4. The guide block according to claim 1 or 2, A guide block, wherein the first contact surface and the second contact surface are both conical surfaces.

5. When performing friction stir welding on an inner corner formed by a pair of workpieces, at least one of whose surfaces is a curved surface, A friction stir welding method using a guide block having a guide hole that rotatably holds a stirring pin, a first contact surface that contacts one of a pair of workpieces, a second contact surface that contacts the other of the pair of workpieces, and flat portions formed on both ends of a ridge line at an intersection between the first contact surface and the second contact surface, wherein at least the first contact surface is a curved surface that can come into close contact with the surface of one of the workpieces, the surface of which is a curved surface.

Images