JP5853472B2 - Friction stir welding tool - Google Patents

Description

  The present invention relates to a friction stir welding tool, and more particularly, to a friction stir welding tool having a probe at a tip.

  One method of joining metal structural materials such as aluminum is a friction stir welding method. This friction stir welding method is disclosed in, for example, Japanese Patent Application Laid-Open No. 2001-314982 (Patent Document 1).

  According to the joining method described in Japanese Patent Application Laid-Open No. 2001-314982, the tip of a rotating friction stir welding tool is pressed from above onto two workpieces arranged in a stacked manner. The material to be welded around the tool tip is heated and softened by the frictional heat generated by the pressing, and the tool tip is inserted into the material to be joined. By agitating the material to be joined at the tip of the rotating tool, the materials to be joined are integrated and joined at the joining point.

  A tool used for this friction stir welding is disclosed in, for example, Japanese Patent Application Laid-Open No. 7-505090 (Patent Document 2) and Japanese Patent Application Laid-Open No. 11-33750 (Patent Document 3).

  JP-A-7-505090 discloses three types of probes as friction stir welding tools having a conical shape with a sharp tip, a truncated cone shape with a flat tip, and a substantially cylindrical shape with a tip having a curvature. Is disclosed.

  Japanese Patent Application Laid-Open No. 11-33750 discloses a probe in which a cone having a bottom surface of a circle having a smaller diameter than a circular bottom surface is provided on the bottom surface of a cylindrical portion as a tool for friction stir welding.

JP 2001-314982 A JP 7-505090 Gazette JP 11-33750 A

  The cone-shaped probe having a sharp tip described in Japanese Patent Publication No. 7-505090 has a low tip strength because the tip has a sharp angle. When using this probe to join a material with high hardness such as steel, the probe tends to bend or break.

  The probe having a truncated cone shape described in Japanese Patent Publication No. 7-505090 has a flat truncated cone, and the probe does not bite well against the material to be joined. If this bite is not good, an excessive force is applied to the probe when the probe and the material to be joined come into contact with each other, so that the probe tends to be lost.

  In the case of a substantially cylindrical probe having a curvature at the tip described in Japanese Patent Publication No. 7-505090, when joining a hard material such as high-tensile steel, the joining position deviates from the target position. Or the probe is easily lost.

  The probe described in Japanese Patent Laid-Open No. 11-33750 has a conical tip angle of 90 ° to 120 °, so that the strength of the tip of the probe is weak and easily lost.

  Therefore, a main object of the present invention is to provide a friction stir welding tool that is not easily lost even when a hard material to be joined is joined.

  The friction stir welding tool according to the present invention includes a probe at the tip. The probe includes a base portion having a circular upper surface and a conical portion whose bottom surface is the upper surface of the base portion. The bottom diameter is the same as the top diameter. The angle of the tip of the conical part is 130 ° or more and 170 ° or less.

  According to the friction stir welding tool according to the present invention, the angle of the tip of the conical portion is 130 ° or more, and therefore the strength of the probe is high compared to the case where the angle of the tip is 120 ° or less. Further, since the angle of the tip of the conical portion is 170 ° or less, the probe is smoothly inserted into the material to be joined as compared with the case where the tip is flat. Therefore, an excessive force is not applied to the probe, so that the probe is not easily broken or deformed. In addition, since the tip of the probe is a cone, compared to a case where the tip is flat, the material to be joined is better bitten, and it is difficult to deviate from the aim of the joining position. Furthermore, since the angle of the tip of the cone is 130 ° or more, the height of the cone is shorter compared to the case where the angle of the tip is 120 ° or less. Can be long. Therefore, the bonding strength of the material to be bonded is increased.

In the friction stir welding tool described above, the platform is preferably a cylinder.
In the friction stir welding tool described above, the platform is preferably a truncated cone whose diameter decreases toward the tip. As a result, resistance when the tool is pulled out from the material to be bonded is reduced, the material to be bonded is difficult to lift, and the probe is difficult to break.

  Preferably, the friction stir welding tool has a spiral thread groove on the side surface of the probe.

  Thereby, since the plastic flow of a to-be-joined material is promoted when joining a to-be-joined material, a to-be-joined material can be joined with high intensity | strength.

  Preferably, the friction stir welding tool further includes a shoulder that is in contact with the lower surface of the pedestal and has a diameter that is larger than the diameter of the lower surface. Thereby, the material to be joined is heated by the friction between the shoulder and the material to be joined, the plastic flow is promoted, and the joining strength is improved.

  In the friction stir welding tool described above, the friction stir welding tool is preferably used for joining high strength steel having a tensile strength of 340 MPa or more.

  According to this, since it bites well against high-tensile steel having a tensile strength of 340 MPa or more, the position of the hitting point is difficult to shift and the probe is not easily broken.

  In the friction stir welding tool described above, the friction stir welding tool is preferably used for spot welding.

  In friction stir spot welding, since the probe is repeatedly inserted into and pulled out from the material to be joined, the number of times the probe contacts the material to be joined increases. When joining with a conventional probe, the probe is likely to be damaged or deformed. However, according to this friction stir welding tool, the load on the probe is low, so it is difficult to be damaged or deformed. , Tool life is also prolonged.

  According to the friction stir welding tool of the present invention, it is possible to effectively prevent the probe from being lost or deformed even when a hard material to be joined is joined.

It is a conceptual diagram of the friction stir welding apparatus which has the tool for friction stir welding based on this invention. It is a figure which shows an example of the tool for friction stir welding which concerns on this invention. It is a figure which shows an example of the tool for friction stir welding which concerns on this invention. It is a figure which shows an example of the tool for friction stir welding which concerns on this invention. It is a figure which shows an example of the tool for friction stir welding which concerns on this invention. It is the schematic which shows the state which is joining the to-be-joined material with the tool for friction stir welding which concerns on this invention. It is the schematic which shows the state which has joined the to-be-joined material with the tool for friction stir welding which concerns on this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and description thereof will not be repeated.

  First, the structure of the friction stir welding apparatus using the friction stir welding tool in one embodiment of the present invention will be described with reference to FIG.

  As shown in FIG. 1, the friction stir welding apparatus 10 is for joining materials to be joined by friction stirring, and includes a friction stir welding tool 1, a rotating body 11, a bearing 12, an induction motor 13, and the like. The guide rail 14, the servo motor 15, and the frame 16 are mainly included.

  The friction stir welding tool 1 is configured to be rotatable and vertically movable with respect to the material to be joined in order to generate the friction stir.

  The mechanism for rotating the friction stir welding tool 1 includes a rotating body 11, a bearing 12, and an induction motor 13. The rotating body 11 is for fixing and supporting the friction stir welding tool 1. The bearing 12 has a substantially cylindrical shape, and accommodates the rotating body 11 therein and rotatably supports it. The induction motor 13 is configured to be able to apply a driving force for rotation to the rotating body 11 by being connected to the rotating body 11.

  The mechanism for moving the friction stir welding tool 1 up and down includes a guide rail 14 and a servo motor 15. The guide rail 14 is a part that guides the vertical movement of the induction motor 13 and the bearing 12 along the axis X that is the rotation center of the friction stir welding tool 1. The servo motor 15 is a power source for moving the induction motor 13 and the bearing 12 up and down along the guide rail 14.

  The frame 16 accommodates the servo motor 15 therein and supports the induction motor 13 and the bearing 12 via the guide rail 14. The receiving member 17 is fixed to the lower side of the frame 16 and is a portion on which a material to be joined is mounted.

  Next, the structure of the friction stir welding tool 1 according to the embodiment of the present invention will be described with reference to FIGS.

(Embodiment 1)
As shown in FIG. 2, the friction stir welding tool 1 according to the first embodiment has a probe 4 and a shoulder 5. The probe 4 is a portion that first comes into contact with the materials to be joined when two materials to be joined are joined, and the probe 4 has a base portion 3 and a cone portion 2. The base part 3 is provided between the conical part 2 and the shoulder 5 and supports the conical part 2. The shape of the upper surface of the base part 3 is a circle.

  In the first embodiment, the pedestal 3 is a cylinder, but the shape of the pedestal 3 is not limited to a cylinder. The shape of the pedestal 3 is sufficient if the upper surface is a circle, and the shape of the pedestal 3 may be, for example, a cylinder. The conical portion 2 is a conical portion having the upper surface of the base portion 3 as a bottom surface. The upper surface of the base part 3 and the bottom surface of the conical part 2 have the same diameter. The angle of the tip of the cone portion 2 is the angle θ of the tip of the triangle formed when the cone is cut along a plane passing through the apex of the cone and the center point of the bottom surface. The angle θ of the tip is 130 ° or more and 170 ° or less.

  The columnar base 3 and the conical part 2 are usually formed integrally. In this case, the upper surface of the columnar base 3 and the bottom surface of the conical part 2 are the boundary surface (the one-dot chain line AA) between the cylindrical part (the base part 3) and the conical part (the conical part 2). (Surface to show). The boundary surface A-A is the top surface of the cylindrical base portion 3 when viewed as the cylindrical base portion 3, and the bottom surface of the conical portion 2 when viewed as the conical portion 2. The same applies to the upper surface of the base portion 3 and the bottom surface of the conical portion 2 in Embodiments 2 to 4 described later.

Next, the effect of the friction stir welding tool 1 of Embodiment 1 will be described.
According to the friction stir welding tool 1 of the first embodiment, since the angle θ of the tip of the conical portion 2 is 130 ° or more, the probe 4 is compared with the case where the angle θ of the tip is 120 ° or less. High strength. Since the strength of the probe 4 is increased, bending and chipping of the probe 4 can be suppressed even when a material having high hardness is subjected to friction stir welding. Further, since the angle θ of the tip of the conical portion 2 is 170 ° or less, the probe 4 is smoothly inserted into the material to be joined as compared with the case where the tip is flat. Therefore, an excessive force is not applied to the probe 4 when the probe 4 is inserted into the material to be joined, so that the probe 4 is not easily broken or deformed.

  Further, since the tip shape of the probe 4 is a cone, compared to the case where the tip shape is flat or the tip has a curvature, the bite to the material to be joined is better and it is difficult to deviate from the aim of the joining position. . For this reason, since it is suppressed that an excessive force is applied to the probe 4 when the probe 4 and the material to be joined come into contact with each other, the loss of the probe 4 is suppressed.

  Furthermore, since the angle θ of the tip of the cone part 2 is 130 ° or more, the height of the cone part 2 can be shortened as compared with the case where the angle θ of the tip is 120 ° or less, and accordingly, the joining is performed accordingly. It is possible to increase the length of the base part 3 involved in the process. Therefore, the bonding strength of the material to be bonded is increased.

(Embodiment 2)
As shown in FIG. 3, the shape of the base part 3 of the friction stir welding tool 1 according to the second embodiment is a truncated cone. That is, the diameter of the truncated cone becomes smaller toward the tip of the tool (in other words, the apex of the cone portion 2). The shape of the surface of the pedestal 3 that is in contact with the conical portion 2 is a circle, and the shape of the surface of the pedestal 3 that is in contact with the shoulder 5 is also a circle. On the upper surface of the truncated cone, a conical portion 2 having the upper surface of the truncated cone as a bottom surface is provided. The angle θ of the tip of the cone portion 2 is 130 ° or more and 170 ° or less.

  The configuration of the second embodiment is different from the configuration of the first embodiment in the shape of the base portion 3. Since the configuration of the second embodiment other than this is the same as the configuration of the first embodiment described above, the same reference numerals are given to the same elements, and the description thereof will not be repeated.

(Embodiment 3)
As shown in FIG. 4, the probe 4 of the friction stir welding tool 1 according to the third embodiment has a columnar base portion 3 and a conical portion 2. A spiral thread groove 6 is provided on the side surface of the base 3. It is preferable that the screw groove portion 6 has a spiral shape that is a reverse screw with respect to the direction in which the probe 4 rotates. When the probe 4 is compared with a screw, the spiral thread groove that is a reverse screw with respect to the direction in which the probe 4 rotates is the front side of the probe 4 when the probe 4 rotates (in other words, the tip of the probe). It is a spiral thread groove that moves to the opposite side.

  The configuration of the third embodiment differs from the configuration of the first embodiment in the presence or absence of the thread groove portion 6. The third embodiment has the screw groove portion 6, but the first embodiment does not have the screw groove portion 6. Since the configuration of the third embodiment other than this is the same as the configuration of the first embodiment described above, the same elements are denoted by the same reference numerals, and the description thereof will not be repeated.

  In this Embodiment 3, since the plastic flow of the materials to be joined is promoted when the two materials to be joined are formed by forming the screw groove portions 6 on the side surfaces of the base portion 3, the materials to be joined can be obtained with high strength. Can be joined.

(Embodiment 4)
As shown in FIG. 5, the probe 4 of the friction stir welding tool 1 according to the fourth embodiment has a truncated cone-shaped platform 3 and a cone 2. A spiral thread groove 6 is provided on the side surface of the base 3. It is preferable that the screw groove portion 6 has a spiral shape that is a reverse screw with respect to the direction in which the probe 4 rotates. The definition of the reverse screw is the same as the definition described in the third embodiment.

  The configuration of the fourth embodiment differs from the configuration of the second embodiment in the presence or absence of the thread groove portion 6. The fourth embodiment has the thread groove 6, but the second embodiment does not have the thread groove 6. Since the structure of Embodiment 4 other than this is the same as that of Embodiment 2 mentioned above, the same code | symbol is attached | subjected about the same element and the description is not repeated.

  Also in the fourth embodiment, by forming the screw groove portion 6 on the side surface of the base portion 3, as in the third embodiment, the plastic flow of the materials to be joined is promoted when two materials to be joined are joined. Therefore, the materials to be joined can be joined with high strength.

  The friction stir welding tool 1 described in the first to fourth embodiments is preferably used for joining high-tensile steel having a tensile strength of 340 MPa or more. Since these friction stir welding tools 1 have good bite against high-tensile steel having a tensile strength of 340 MPa or more, the striking point position is difficult to shift and the probe 4 is not easily broken.

  The friction stir welding tool 1 described in the first to fourth embodiments is preferably used for point joining. In friction stir spot welding, the probe 4 is repeatedly inserted into and pulled out from the material to be joined, so that the number of times the probe 4 contacts the material to be joined increases. In the case of joining using a conventional probe, the probe 4 is easily lost or deformed. However, according to the friction stir welding tool 1 according to the present invention, the load on the probe 4 is low. And the life of the friction stir welding tool 1 is prolonged.

  Next, a method for spot-joining two materials to be joined using the friction stir welding tool 1 according to the first to fourth embodiments of the present invention will be described using the first embodiment as an example with reference to FIG. .

  As shown in FIG. 6, first, the two materials to be joined 30, 31 are arranged one above the other. The friction stir welding tool 1 is disposed on the joining position of the materials 30 and 31 to be joined. Thereafter, the induction motor 13 (FIG. 1) is driven to rotate the friction stir welding tool 1 in the rotation direction 34. With the friction stir welding tool 1 rotated, the friction stir welding tool 1 is moved downward in the direction of the axis X. When the tip of the probe 4 of the friction stir welding tool 1 reaches the surface of the workpiece 30, frictional heat is generated by friction between the rotating probe 4 and the workpiece 30. Part of the material to be joined 30 is softened by the frictional heat, and the probe 4 is inserted into the material to be joined 30.

  When the friction stir welding tool 1 is further lowered after the probe 4 is inserted into the material to be joined 30, the lower surface of the shoulder 5 also contacts the material to be joined 30. Friction heat is generated by the friction between the shoulder 5 and the material to be joined 30, and the vicinity 32 of the joint is further heated. By rotating with the probe 4 and the shoulder 5 inserted into the material to be joined 30 heated by the frictional heat, plastic flow occurs in the material to be joined 30 and the vicinity of the joining point is agitated.

  After integrating the materials to be joined 30 and 31 at the joining point, the probe 4 is pulled out from the materials to be joined 30 and 31 along the drawing direction 35, whereby the two materials to be joined are spot-welded at the joining point. .

  Next, a method for wire-joining two materials to be joined using the friction stir welding tool 1 according to the first to fourth embodiments of the present invention will be described using the first embodiment as an example with reference to FIG. .

  As shown in FIG. 7, first, the two materials 21 and 22 are arranged so as to face each other. The friction stir welding tool 1 is disposed above the butted portion 23 of the two materials 21 and 22 to be joined. The induction motor 13 is driven and the friction stir welding tool 1 is rotated in the rotation direction 25. When the friction stir welding tool 1 is moved downward in the axis X direction with the friction stir welding tool 1 rotated, the tip of the probe 4 of the friction stir welding tool 1 contacts the workpieces 21 and 22. .

  While rotating the probe 4, the probe is moved in the direction of the arrow 24 along the butted portion 23 of the materials 21 and 22 to be joined. The frictional heat between the probe 4 and the materials 21 and 22 and the rotation of the probe 4 cause a plastic flow in the materials 21 and 22 to stir the vicinity of the joint. When the probe 4 moves in the lateral direction of the arrow 24, the part to be agitated is naturally cooled and the materials 21 and 22 are solidified, whereby the two materials 21 and 22 are linearly joined.

Next, examples of the present invention will be described.
The relationship between the shape of the probe 4 of the friction stir welding tool 1, the strength of the probe 4, the goodness of biting of the probe 4 against the material to be bonded, and the bonding strength of the material to be bonded was examined.

  The material of the friction stir welding tool 1 used in this experiment was a cemented carbide with a WC (tungsten carbide) particle size of 2 μm and a Co (cobalt) content of 6 wt% (weight percent). Friction stir welding tools 1 of Examples 1-1 to 1-9 in which the shape of the base 3 and the angle θ of the tip of the conical part 2 were changed were prepared. The overall length of the friction stir welding tool 1 was 32 mm, and the friction stir welding tool 1 was fixed to a tool holder made of SKD61 by shrink fitting. The length of the shrink-fitted part was 20 mm. The diameter of the shoulder 5 was 10 mm, and the length from the probe tip to the shoulder surface was 2.0 mm.

  Each of the friction stir welding tools 1 of Examples 1-1 to 1-4 has a shape having a base portion 3 having a circular upper surface and a conical portion 2 having the upper surface of the base portion 3 as a bottom surface. The shape of the base part 3 was a cylinder with a diameter of 4 mm. The diameter of the bottom surface of the cone part 2 was 4 mm. The angles of the tip of the cone portion 2 were 130 °, 140 °, 160 °, and 170 °, respectively.

  Each of the friction stir welding tools 1 of Examples 1-5 to 1-7 has a shape having a base portion 3 having a circular upper surface and a conical portion 2 having the upper surface of the base portion 3 as a bottom surface. The shape of the platform 3 was a truncated cone. The upper surface of the pedestal 3 (the tip side of the probe 4) was a circle having a diameter of 3 mm. The bottom surface of the base 3 (the side opposite to the tip side of the probe 4) was a circle having a diameter of 4.5 mm. The diameter of the bottom surface of the truncated cone was 3 mm. The angles of the tip of the cone portion 2 were 140 °, 150 °, and 160 °, respectively.

  As a friction stir welding tool 1 of Example 1-8, a spiral which is a reverse screw with respect to the rotation direction of the friction stir welding tool 1 on the side surface of the base 3 of the friction stir welding tool 1 of Example 1-2. A tool in which a threaded groove portion 6 was formed was prepared. As the friction stir welding tool 1 of Example 1-9, a spiral that is a reverse screw with respect to the rotation direction of the friction stir welding tool 1 on the side surface of the base 3 of the friction stir welding tool 1 of Example 1-6 A tool in which a threaded groove portion 6 was formed was prepared. The pitch of the screw was 0.7 mm.

  For comparison, the friction stir welding tool 1 of Comparative Examples 1-1 to 1-4 was prepared. The material of the friction stir welding tool 1 was the same as that of Examples 1-1 to 1-9. The overall length of the friction stir welding tool 1, the diameter of the shoulder, and the length from the probe tip to the shoulder surface were also the same as in Examples 1-1 to 1-9.

  In each of the friction stir welding tools 1 of Comparative Examples 1-1 to 1-3, as in Examples 1-1 to 1-4, the base 3 having a circular upper surface and the upper surface of the base 3 as the bottom It was set as the shape which has the cone part 2 to do. However, the angle of the tip of the probe 4 was set to be less than 130 ° or greater than 170 °. The probe 4 of Comparative Example 1-4 was made into the shape which has the column-shaped base part 3 and the cone part which has the bottom face of a diameter smaller than the diameter of the upper surface of the base part 3 on the upper surface of the base part 3. FIG. The diameter of the columnar base 3 was 4 mm. The diameter of the bottom surface of the conical part was 2 mm. The height of the cone portion was 1 mm, and the angle of the tip of the cone was 90 ° (in other words, the inclination angle of the cone surface was 45 °).

Next, the contents of the experiment will be described.
The durability of the friction stir welding tool 1 and the evaluation of the bite to the material to be joined were evaluated by stacking and joining two steel plates using a friction stir spot welding device. A 340 MPa class high-tensile steel plate having a thickness of 1.2 mm was used as a material to be joined. The rotation speed of the friction stir welding tool 1 for friction stir spot welding was set to 3000 rpm, and the joining load was set to 600 kgf. The joining time was 2.5 seconds, and the maximum number of hits was 1000.

  Evaluation of the joining strength of the materials to be joined was carried out in accordance with the Japanese Industrial Standards evaluation method (JIS Z3136). A shear test was performed using a normal width test piece having a plate width of 30 mm, a stacking margin of 30 mm, and a test piece length of 100 mm.

  Next, experimental results will be described using Table 1.

  First, the result of the durability test of the friction stir welding tool 1 will be described. In each of the friction stir welding tools 1 of Examples 1-1 to 1-9 of the present invention, no large chipping or breakage is observed in the probe 4 even after a 1000-point joining test, and the tool has good durability. It was confirmed. On the other hand, in the friction stir welding tool 1 of Comparative Examples 1-1 to 1-4, it was confirmed that the probe had a defect or breakage before the 1000-spot joining test was completed. Specifically, the probes of Comparative Examples 1-1 to 1-4 were deficient or broken during the period from the start of the point joining test to the 12th to the 67th.

  Next, the result of the good bite with respect to the to-be-joined material of the tool 1 for friction stir welding is demonstrated. The goodness of biting was evaluated by examining how much the actual bonding position was from the target. In order to investigate how much the joining position deviates from the target position, the deviation from the aim at the center of the hit point is measured for the first hit point to the tenth hit point of the above-mentioned joining test, and the average value of the ten points is obtained. Asked. As shown in Table 1, in the friction stir welding tool 1 of Examples 1-1 to 1-9 of the present invention, the deviation from the aim at the center of the hitting point is 0.4 mm or less, and from the aiming position. It was confirmed that the deviation was small. On the other hand, in Comparative Example 1-1 and Comparative Example 1-3, the friction stir welding tool 1 did not bite into the material to be joined, and the deviation from the center of the hit point was 1.6 to 1.8 mm. . In Comparative Example 1-2 and Comparative Example 1-4, the deviation from the center of the hit point was small, but the probe 4 was lost or broken during the durability test.

  Next, the result of the bonding strength of the materials to be bonded will be described. It was confirmed that the friction stir welding tool 1 of Examples 1-1 to 1-9 of the present invention has a good bonding strength of a shear strength of 6.1 to 9.6 kN. The friction stir welding tool 1 of Examples 1-8 and 1-9 is a tool in which a spiral thread groove 6 is formed on the side surface of the base 3, and has the same probe 4 shape as the spiral thread groove 6. High joint strength was obtained as compared with the friction stir welding tool 1 of Example 1-2 and Example 1-6 without the above. On the other hand, in the friction stir welding tool 1 of Comparative Example 1-2, the length of the conical part was long and the length of the cylindrical part involved in the joining was short, so the joining strength was 4.9 kN. In Comparative Example 1-4, the length of the conical part was as long as 1 mm, and the length of the cylindrical part involved in the joining was short, so the joining strength was 5.1 kN.

  From the above results, the probe 4 has the base portion 3 having a circular upper surface and the conical portion 2 having the upper surface of the base portion 3 as the bottom surface, and the angle θ of the tip of the conical portion 2 is 130 ° or more and 170 ° or less. It was confirmed that the friction stir welding tool 1 has good durability, good biting with respect to the material to be joined, and high joining strength of the material to be joined can be obtained.

Next, another embodiment of the present invention will be described.
The relationship between the shape of the probe 4 of the friction stir welding tool 1 and the strength of the probe 4 was examined.

  As the friction stir welding tool 1 used in this experiment, the friction stir welding tool 1 having the same shape and material as the friction stir welding tool 1 used in Example 1 was used.

Next, the contents of the experiment will be described.
In the friction stir welding apparatus as described with reference to FIG. 7, two steel plates as the materials to be joined were butted together, and the two steel plates were wire joined, and the durability of the friction stir welding tool 1 was examined. A 340 MPa class high-tensile steel plate having a thickness of 2.5 mm was used as a material to be joined. The rotation speed of the friction stir welding tool was set to 800 rpm. The joining speed was 2 mm per second, and the tilt angle of the friction stir welding tool was 2 °. The amount of friction stir welding tool push-in was 2.2 mm, and the maximum joint distance was 4 m (4000 mm). The length of the plate was set to 500 mm, the plate was replaced every 400 mm, and it was confirmed whether the friction stir welding tool was damaged.

  Next, experimental results will be described with reference to Table 2.

  In the above-described line joining test, in the friction stir welding tool 1 of Examples 2-1 to 2-9 of the present invention, any friction stir welding tool 1 is used for friction stir welding even after 4 m (4000 mm) joining. No major abnormality was observed in the tool 1, and it was confirmed that the tool 1 had good durability. For comparison, a wire joining test was performed using the friction stir welding tool 1 having the same material and shape as those used in Comparative Examples 1-1 to 1-3. In the friction stir welding tool 1 of Comparative Example 2-1, since the tip of the probe 4 is flat, the biting on the material to be joined is poor and the load on the material to be joined is large. Was broken. In the friction stir welding tool 1 of Comparative Example 2-2, since the tip angle of the probe 4 is as small as 120 °, the strength of the tip portion is weak, and the tip of the probe is missing at the time of 800 mm joining. In the friction stir welding tool of Comparative Example 2-3, since the tip angle was as large as 175 °, the biting to the material to be joined was poor, and the probe 4 was broken at the time of 1200 mm joining.

  From the above results, the probe 4 has the base portion 3 having a circular upper surface and the conical portion 2 having the upper surface of the base portion 3 as the bottom surface, and the angle θ of the tip of the conical portion 2 is 130 ° or more and 170 ° or less. This friction stir welding tool 1 was confirmed to have good durability even in friction stir welding.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The present invention can be suitably used for a friction stir welding tool.

  DESCRIPTION OF SYMBOLS 1 Tool for friction stir welding, 2 cone part, 3 base part, 4 probe, 5 shoulder, 6 thread groove part, 10 friction stir welding apparatus, 11 rotary body, 12 bearing, 13 induction motor, 14 guide rail, 15 servo motor, 16 frame, 17 receiving member, 21, 22 material to be joined, 23 abutting part, 24 movement direction, 25 rotation direction, 30, 31 material to be joined, 32 near joint part, 33 joint point, 34 rotation direction, 35 drawing direction.

Claims (3)

A friction stir welding tool with a probe at the tip,
The probe is
A base with a circular top surface;
A conical portion having the upper surface as a bottom surface,
The bottom surface has the same diameter as the top surface;
Ri said angle der 130 ° or 170 ° or less of the tip of the conical portion,
The base part is a truncated cone whose diameter decreases toward the tip,
The friction stir welding tool is used for joining high strength steel having a tensile strength of 340 MPa or more,
The friction stir welding tool is used for spot welding . The tool for friction stir welding according to claim 1, wherein the tool has a spiral thread groove on a side surface of the probe. 3. The friction stir welding tool according to claim 1, further comprising a shoulder that is in contact with a lower surface of the base portion and has a diameter of a surface in contact with the lower surface that is larger than a diameter of the lower surface.

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