JP2005199281A - Tool for friction stir welding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provided a friction stir welding tool which force-fits a probe pin extended from the distal end face of a rotor rotating at high speed into a joint portion of a member to be joined and which then moves the probe pin along the joint portion to join the member to be joined at the joint portion by friction stir welding, in which wearing and buckling of the rotor or the probe pin and also thermal deformation or the like of the joint portion of the member to be joined are suppressed. <P>SOLUTION: The friction stir welding tool is disclosed which force-fits the probe pin 12 extended from the distal end face 11a of the rotating rotor 11 into the joint portion 1a of the member to be joined 1 and which then moves the probe pin along the joint portion to join the member to be joined at the joint portion by friction stir welding, wherein a part of the probe pin and the rotor that come into contact at least with the member to be joined is composed of WC-based cemented carbide containing 5-18 wt% Co. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a friction stir welding tool used for friction stir welding of members to be joined made of a metal material such as aluminum, aluminum alloy, magnesium alloy, copper alloy, titanium alloy and the like. The present invention is characterized in that the members to be joined can be friction stir welded together and the members to be joined can be joined appropriately.

  Conventionally, in joining members to be joined made of metal materials such as aluminum, aluminum alloy, magnesium alloy, copper alloy, and titanium alloy, conventionally, methods such as electric resistance welding, arc welding, and gas welding are generally used. It is used.

  In recent years, it has been proposed to join members to be joined by friction stir welding instead of such welding.

  Here, in joining the members to be joined by friction stir welding, generally, as shown in FIG. 1, the probe pin 12 provided with a screw portion (not shown) on the outer periphery is the tip surface 11 a of the rotor 11. Using the friction stir welding tool 10 extended from the above, the probe pin 12 extended from the tip end surface 11a of the rotor 11 is rotated while rotating the friction stir welding tool 10 at a high speed. The members to be joined 1 are pressed into the mutual joining portions 1a and the tip end surface 11a of the rotor 11 is brought into contact, and the friction stir welding tool 10 is moved along the joining portions 1a of the members to be joined 1 in this state. They are joined together in sequence along the joint 1a.

  That is, in the friction stir welding tool 10, the member 1 to be joined is plastically fluidized and fluidized by the frictional heat between the rotor 11 and the probe pin 12 rotating at a high speed and the member 1 to be joined as described above. The joined member 1 is agitated by a screw portion provided on the outer periphery of the probe pin 12 at the joining portion 1a, and then cooled to join the joined members 1 at the joining portion 1a. It has become.

  And when joining the to-be-joined members 1 mutually by friction stir welding in this way, the to-be-joined members 1 can be joined at low temperature compared with welding, and the joining defect by thermal deformation and oxidation at the time of joining is suppressed. In addition, there is an advantage that the entire joint portion 1a is uniformly joined, and that different materials can be joined easily.

  Here, as a material constituting the rotor 11 and the probe pin 12 in the friction stir welding tool 10 described above, tool steel and die steel are generally used.

  However, as described above, the friction stir welding tool 10 is rotated at a high speed so that the probe pin 12 is press-fitted into the joint between the members to be joined 1 and the tip surface of the rotor 11 is brought into contact with the member 1 to be joined. When the joined member 1 is plastically fluidized by frictional heat, the fluidized joined member 1 is welded to the rotor 11 or the probe pin 12, or the rotor 11 or the probe pin 12 becomes high temperature. When the friction stir welding is performed continuously, the rotor 11 and the probe pin 12 are buckled or the bonded portion 1a of the bonded member 1 is thermally deformed. .

  For this reason, in recent years, the members to be joined are subjected to friction stir welding while forcibly cooling the members to be joined (see, for example, Patent Document 1), and the probe pins are made of an Fe—Cr alloy ( For example, see Patent Document 2).

  However, when the friction stir welding is performed while forcibly cooling the member to be bonded as described above, it is possible to suppress the thermal deformation of the bonded portion of the member to be bonded. There is a problem in that the member is welded to the rotor or the probe pin, and the rotor or the probe pin is worn extremely.

Moreover, even when the probe pin is made of an Fe—Cr alloy, there are still problems such as the fluidized member to be welded to the rotor and the probe pin, and the rotor and the probe pin being worn. .
JP-A-11-226757 JP 2000-343243 A

  This invention makes it a subject to solve the above problems in the tool for friction stir welding used for friction stir welding of to-be-joined members.

  That is, in this invention, the friction stir welding tool is rotated at a high speed, the probe pin is press-fitted into the joined portion of the member to be joined, and the tip surface of the rotor is brought into contact with the member to be joined, and the member to be joined is caused by frictional heat. When the probe pin is moved along the joint in this state and the member to be joined is subjected to friction stir welding at the joint, the fluidized member to be welded to the rotor or the probe pin is welded. Or the wear of the rotor or probe pin is sufficiently suppressed, and when the friction stir welding is continuously performed, the rotor or probe pin buckles or is joined to the joined parts to be joined. It is possible to prevent the member from being thermally deformed, to allow the member to be joined to be friction stir welded over a long period of time, and to appropriately join the member to be joined at the joint. It it is an object of.

  In the present invention, in order to solve the above-described problems, the probe pin 12 extended from the distal end surface 11a of the rotating rotor 11 is press-fitted into the joint 1a of the member 1 to be joined, and the joint 1a is inserted into the joint 1a. In the friction stir welding tool for moving the probe pin 12 along the friction stir welding of the member to be joined at the joint 1a, at least the probe pin 12 and the rotor 11 in contact with the member to be joined 1 are Was made of a WC cemented carbide containing 5 to 18% by weight.

  In the friction stir welding tool according to the present invention, it is preferable to use a cemented carbide having a thermal conductivity of 60 W / m · K or more.

  As in the friction stir welding tool according to the present invention, at least the probe pin and the rotor that are in contact with the member to be joined are composed of a WC-based cemented carbide containing 5 to 18% by weight of Co. The friction stir welding tool is rotated at high speed, the probe pin is press-fitted into the joint of the member to be joined, and the tip of the rotor is brought into contact with the friction stir welding tool. When the member to be welded is plastically fluidized by heat, the fluidized member to be welded is suppressed from welding to the probe pin and the rotor, and wear of the probe pin and the rotor due to friction is reduced.

  In addition, if the probe pin and the rotor are made of the cemented carbide as described above, the thermal conductivity in the probe pin and the rotor is higher than that in the case of using tool steel or die steel. When a cemented carbide with a thermal conductivity of 60 W / m · K or more is used, heat can be efficiently diffused and released through the probe pin and the rotor even when friction stir welding is performed continuously. Thus, it is possible to prevent the rotor and the probe pin from buckling and the joined portion of the joined members to be joined from being thermally deformed.

  As a result, when the friction stir welding tool according to the present invention is used, the members to be welded can be friction stir welded over a long period of time, and the members to be joined can be joined appropriately.

  Hereinafter, a friction stir welding tool according to an embodiment of the present invention will be specifically described with reference to the accompanying drawings.

  In the friction stir welding tool 10 according to this embodiment, as shown in FIG. 2, the probe pin 12 is extended from the tip end surface 11 a of the rotor 11, while the rotating device ( A shank portion 13 having a large diameter to be attached to the probe pin 12 is provided, and a thread portion 12a that is reversely twisted in the rotational direction of the friction stir welding tool 10 is formed on the outer periphery of the probe pin 12, The tip surface 11a of the rotor 11 is formed to be recessed from the outer peripheral side toward the center where the probe pin 12 is provided.

  Here, in the friction stir welding tool 10 in this embodiment, as shown in FIG. 3, the rotator 11, the probe pin 12, and the entire shank portion 13 are WC containing 5 to 18 wt% Co. It is integrally formed of a cemented carbide. The WC cemented carbide having a Co content of 5 to 18% by weight is used because the friction stir welding tool 10 is easily broken when the Co content is less than 5% by weight. On the other hand, if the Co content exceeds 18% by weight, the member 1 to be bonded is easily welded to the rotor 11 or the probe pin 12 when the members to be bonded 1 are bonded to each other by friction stir welding. .

  Then, in the friction stir welding of the member 1 to be welded at the joint 1a using the friction stir welding tool 10 in this embodiment, as in the conventional friction stir welding tool 10, as shown in FIG. While rotating the friction stir welding tool 10 at a high speed, the probe pin 12 is press-fitted into the joint 1a between the members 1 to be joined, and the tip 11a of the rotor 11 is brought into contact with the rotor 11 to rotate. Further, the member 1 to be joined in the joining portion 1a is plastically fluidized by frictional heat between the probe pin 12 and the member 1 to be joined. Then, the fluidized member 1 thus fluidized is agitated by the screw portion 12a provided on the outer periphery of the probe pin 12, and the friction stir welding tool 10 is moved along the joint 1a of the member 1 in this state. The members to be joined 1 are joined together in order along the joining portion 1a.

  Here, in the friction stir welding tool 10 in this embodiment, as described above, the rotor 11, the probe pin 12, and the entire shank portion 13 are WC-based cemented carbide containing 5 to 18% by weight of Co. In the case where the member 1 to be joined and the probe pin 12 or the rotor 11 have low affinity, the member 1 to be joined is friction stir welded along the joint 1a as described above. The welded member 1 is suppressed from being welded to the probe pin 12 and the rotor 11, and the wear of the probe pin 12 and the rotor 11 due to friction is reduced.

  Further, the thermal conductivity in the probe pin 12, the rotor 11, and the shank portion 13 is significantly increased. Even when the friction stir welding is continuously performed, heat is transmitted through the probe pin 12, the rotor 11, and the shank portion 13. It is efficiently diffused / released to the outside, and the probe pin 12 and the rotor 11 are prevented from buckling and the joined portion 1a of the joined member 1 to be joined is prevented from being thermally deformed.

  Further, in the friction stir welding tool 10 in this embodiment, when the fluidized member 1 is agitated by the screw portion 12a provided on the outer periphery of the probe pin 12, the screw portion 12a is as described above. Since the direction of rotation of the friction stir welding tool 10 is opposite to the rotational direction, the fluidized member 1 is pressed downward by the action of the screw portion 12a, and the tip end surface 11a of the rotor 11 is pressed. Is recessed from the outer peripheral side toward the center where the probe pin 12 is provided as described above, so that the fluidized joined member 1 is prevented from flowing out from the joining portion 1a. Thus, the members 1 to be joined can be uniformly joined at the joint 1a without forming a cavity or the like.

  In the friction stir welding tool 10 in this embodiment, since the rotor 11, the probe pin 12, and the entire shank portion 13 are integrally formed of the above cemented carbide, the heat is generated as described above. 12 and the rotor 11 and the shank portion 13 are efficiently diffused and discharged to the outside, but the material cost is high. Therefore, as shown in FIG. 4, the rotor 11, the probe pin 12, and a part 13 a of the shank part 13 are integrally formed of the above cemented carbide, while the remaining part 13 b of the shank part 13 is formed as a tool. It is also possible to reduce the cost by using steel or die steel and joining them by brazing or the like to reduce the above-mentioned cemented carbide portion.

  Further, as shown in FIG. 5, the elongated rotor 11 and the probe pin 12 are integrally formed of the above cemented carbide, and a locking portion 11 b is provided on the rear side of the elongated rotor 11. While the notch is formed, a housing portion 13c for inserting the rear side of the rotor 11 provided with the locking portion 11b is provided in the shank portion 13 made of tool steel or die steel. The rotor 11 and the probe pin 12 are integrally formed by inserting the screw 14 against the engaging portion 11b of the rotor 11 inserted into the accommodating portion 13c. Can be fixed to the shank portion 13. In this way, the cost can be reduced by reducing the portion of the cemented carbide, and even when the rotor 11 and the probe pin 12 are worn out, the rotor 11 and the probe pin 12 that are elongated are formed. It is possible to easily replace only the one formed integrally, further reducing the cost, and preparing a plurality of probe pins 12 with different diameters, lengths, etc., and changing them accordingly. Can also be used.

  Further, in the friction stir welding tool 10 in this embodiment, when the portions of the probe pin 12 and the rotor 11 that are in contact with the member to be joined 1 are covered with TiN, TiCN, TiAlN, CrN, DLC (diamond-like carbon), etc., When the members 1 to be joined are friction stir welded as described above, the welding of the members 1 to the rotor 11 and the probe pins 12 is further suppressed.

  Next, the case where the member to be joined is joined using the specific friction stir welding tool according to the embodiment of the present invention and the case where the member to be joined is joined using the friction stir welding tool of the comparative example And the friction stir welding tool according to the embodiment of the present invention is clarified.

(Example 1)
In Example 1, the average particle size of WC is 2 to 3 μm, the Rockwell hardness A scale HRA is 88.5, and the thermal conductivity is 67 W / m · K. Using a hard alloy, as shown in the above embodiment, a friction stir welding tool in which the rotor 11, the probe pin 12, and the entire shank portion 13 were integrally formed of the above cemented carbide was produced. The thermal conductivity was measured with a laser flash.

(Example 2)
In Example 2, the average particle size of WC is 2 to 3 μm, Rockwell hardness A scale HRA is 91.5, and the thermal conductivity is 72 W / m · K. A friction stir welding tool was prepared in the same manner as in Example 1 except that a hard alloy was used.

(Example 3)
In Example 3, the average particle size of WC was 0.8 μm, Rockwell hardness A scale HRA was 92.0, and the superconductivity of WC system containing 13 wt% Co having a thermal conductivity of 47 W / m · K. A friction stir welding tool was prepared in the same manner as in Example 1 except that a hard alloy was used.

Example 4
In Example 4, a WC cemented carbide containing WC with an average particle size of 5 μm, Rockwell hardness A scale HRA of 87.0, and a thermal conductivity of 71 W / m · K containing 10 wt% Co. Otherwise, a friction stir welding tool was prepared in the same manner as in Example 1 above.

(Example 5)
In Example 5, the average particle size of WC was 2 to 3 μm, the Rockwell hardness A scale HRA was 87.5, and the thermal conductivity was 63 W / m · K. A friction stir welding tool was prepared in the same manner as in Example 1 except that a hard alloy was used.

(Comparative Example 1)
In Comparative Example 1, a tool steel having a Rockwell hardness C scale HRC of 57 and a thermal conductivity of 24 W / m · K was used, and other than that, the tool for friction stir welding was performed in the same manner as in Example 1 above. Was made.

(Comparative Example 2)
In Comparative Example 2, a WC super-particle containing 20 wt% Co having an average particle size of WC of 2 to 3 μm, Rockwell hardness A scale HRA of 85.5, and thermal conductivity of 58 W / m · K. A friction stir welding tool was prepared in the same manner as in Example 1 except that a hard alloy was used.

(Comparative Example 3)
In Comparative Example 3, the average particle size of WC is 4-5 μm, Rockwell hardness A scale HRA is 84.0, and the thermal conductivity is 68 W / m · K. A friction stir welding tool was prepared in the same manner as in Example 1 except that a hard alloy was used.

  Then, as a member 1 to be joined, a plate material made of JIS 5000 series aluminum having a thickness of 4 mm is bent into a square tube shape as shown in FIG. Using the friction stir welding tools of Example 1 and Comparative Example 1 described above, and joining in the member 1 to be joined under the conditions of a rotational speed of 1200 rpm and a feed rate of 300 mm / min. Part 1a was friction stir welded.

  As a result, in the friction stir welding tool of Comparative Example 1, the welded member 1 was welded to the probe pin 12 or the tip surface 11a of the rotor 11, and about 1500 welded members 1 were friction stir welded. At that time, wear of the tip of the probe pin 12 and the threaded portion 12a increased, and the service life was reached. On the other hand, in the friction stir welding tool of Example 1, approximately 10,000 welded members 1 could be friction stir welded with almost no welded member 1 welded to the probe pin 12.

  In addition, as the member 1 to be joined, two plate members made of JIS 6000 series aluminum having a thickness of 3 mm are butted as shown in FIG. 7, and the length of the joined portion 1a is 3 m. Using the above-mentioned tools for friction stir welding in Examples 1 to 5 and Comparative Examples 1 to 3 above, the joining portion 1a in the above-mentioned joined member 1 is used under the conditions of a rotational speed of 1500 rpm and a feed rate of 1000 mm / min. Friction stir welding was performed.

  As a result, in the friction stir welding tool of Comparative Example 1, when the total length of the joints 1a subjected to the friction stir welding reaches about 3000 m (about 1000 joints), the tip of the probe pin 12 and the screw The wear of the portion 12a was increased and the service life was reached. On the other hand, in the friction stir welding tool of Example 1, the friction stir welding could be performed until the total length of the joint portion 1a reached about 15000 m (about 5000 pieces).

  In addition, when each of the friction stir welding tools of Examples 1 to 5 and Comparative Examples 1 to 3 is used as described above and the joint 1a of the member to be joined 1 is friction stir welded, the friction stir welding is performed. In addition to examining the presence or absence of welding of the member to be joined 1 to the probe pin 12 and the tip end surface 11a of the rotor 11 in the tool, the deformation at the joint 1a of the member to be joined 1 is examined. The deformation amount when each friction stir welding tool was used was calculated with an index where the deformation amount when used was 1, and the results are shown in Table 1 below.

  As is clear from this result, when using the friction stir welding tools of Examples 1 to 5 and Comparative Examples 2 and 3 using a WC-based cemented carbide containing Co, a comparison using tool steel was made. Compared to the friction stir welding tool of Example 1, the amount of deformation of the joint 1a in the member 1 to be friction stir welded is reduced, and in particular, a cemented carbide having a thermal conductivity of 60 W / m · K or more. In the case of using, the amount of deformation was further reduced.

  In addition, when each friction stir welding tool of Examples 1 to 5 using a WC cemented carbide having a Co content of 18% by weight or less is used, the friction stir welding of Comparative Example 1 using tool steel is used. As compared with the friction stir welding tools of Comparative Examples 2 and 3 using a WC-based cemented carbide with a Co content exceeding 18 wt%, the probe pin 12 and the tip surface 11a of the rotor 11 are compared. Welding of the member 1 to be welded was reduced.

It is the schematic explanatory drawing which showed the state which joins to-be-joined members in a friction stir welding in a junction part using the tool for friction stir welding. It is a schematic front view of the tool for friction stir welding which concerns on one Embodiment of this invention. It is a schematic sectional drawing of the tool for friction stir welding concerning the embodiment. It is the schematic sectional drawing which showed the 1st modification of the tool for friction stir welding which concerns on the same embodiment. It is the schematic sectional drawing which showed the 2nd modification of the tool for friction stir welding which concerns on the same embodiment. It is the perspective view which showed the 1st to-be-joined member made to friction stir weld using the tool for friction stir welding of the Example and comparative example of this invention. It is the perspective view which showed the 2nd to-be-joined member made to friction stir weld using the tool for friction stir welding of the Example and comparative example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 To-be-joined member 1a Joining part 10 Friction stir welding tool 11 Rotor 11a End face of rotor 12 Probe pin 13 Shank part

Claims (2)

  The probe pin 12 extended from the front end surface 11a of the rotating rotor 11 is press-fitted into the joint portion 1a of the member 1 to be joined, and the probe pin 12 is moved along the joint portion 1a. In the friction stir welding tool for friction stir welding the member 1 to be welded, at least a portion of the probe pin 12 and the rotor 11 that are in contact with the member 1 to be welded is a WC-based superconductor containing 5 to 18% by weight of Co. A friction stir welding tool characterized by comprising a hard alloy.   The friction stir welding tool according to claim 1, wherein the cemented carbide has a thermal conductivity of 60 W / m · K or more.

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