JP2005021967A - Friction stirring and joining method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a friction stirring and joining method capable of obtaining excellent joint strength, and joining metals of different thickness with each other without generating burrs on a joined portion. <P>SOLUTION: A thin plate 3 and a thick plate 4 are butted to each other and arranged so that bottom surfaces thereof are on the same plane. Next, a pin part 2 is inclined by the angle θ in the direction opposite to the joining direction, brought into contact with the butted portion of the thin plate 3 to the thick plate 4, and pressed thereagainst in the direction of the butted portion in a rotating manner to allow the pin part 2 to be advanced into the butted portion. The pin part 2 is advanced until an end part of a shoulder part 1 is located between an intermediate part of a step formed by the thin plate 3 and the thick plate 4 and an upper surface of the thin plate 3. The pin part 2 and the shoulder part 1 are moved at the advancing angle θ in a rotating manner so that the pin part 2 passes through a butted surface. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a friction stir welding method for a metal material such as an aluminum alloy, and more particularly to a differential thickness joint friction stir welding method for joining members having different thicknesses.

  The friction stir welding method uses a joining tool provided with a pin portion made of a material harder than the member, and pushes the pin portion into a pair of members that are abutted with each other while rotating the pin portion. In this method, the members are joined together by moving the joining tool while rotating. At this time, the periphery of the pin portion pushed into the member is heated by frictional heat, and plastic flow is generated by the rotation of the joining tool. For this reason, when the joining tool is moved along the abutting surface, the metal on the front surface of the pin portion moves to the rear of the pin while plastically flowing to form a joint structure. The friction stir welding method has a high joint strength and a small strain, so there is little residual stress, and it is possible to join materials, castings, composite materials and dissimilar materials that are susceptible to weld cracking. in use.

  Conventionally, in the friction stir welding, since the pin portion is inserted perpendicularly to the member, when the members having different thicknesses are joined, there is a problem that the agitated material is scattered. Therefore, in the conventional friction stir welding method, when members having different thicknesses are joined, a method of inserting the pin portion obliquely with respect to the abutting surface is applied (see, for example, Patent Documents 1 and 2). . 4A is a cross-sectional view showing the friction stir welding method described in Patent Document 1, and FIG. 4B is a cross-sectional view showing the friction stir welding method described in Patent Document 2. As shown in FIG. 4A, the friction welding method described in Patent Document 1 is a method of inserting the pin portion 11a in a state where the welding tool 11 is inclined toward the thin plate material 12 side. On the other hand, as shown in FIG. 4 (b), the friction welding method described in Patent Document 2 does not change the angle of the welding tool 11, but obliquely in a state in which the members (thin plate material 12 and thick plate material 13) are in close contact. This is a method of arranging and inserting the pin portion 11a. There is also a method of joining with the pin insertion surface flattened (see, for example, Patent Document 3). FIG. 5 is a cross-sectional view showing the friction stir welding method described in Patent Document 3. As shown in FIG. 5, the friction joining method described in Patent Document 3 is performed on a backing 14 on which a step having the same height as the difference between the thickness of the thin plate 12 and the thickness of the thick plate 13 is formed. In this method, the plate member 12 and the thick plate member 13 are arranged to make the upper surface (pin insertion surface) flat, and in this state, the pin 11a is inserted vertically and joined.

JP-A-10-249553 (page 2-4, FIG. 1) JP 2002-11583 A (page 3-5, FIG. 1-2) JP 2000-167676 (Page 3-7, Fig. 1)

  However, the conventional techniques described above have the following problems. In the case of the method described in Patent Document 1, since it is necessary to incline the joining tool 11 in two directions with respect to the abutting surface of the member, a processing machine having two axes for inclination in addition to three orthogonal axes is required. . In addition, in the case of the method described in Patent Document 2, a jig design that tilts the member is necessary. Furthermore, although the method of patent document 3 can use the tool 11 of a normal specification, an ingenuity is needed for the jig | tool for aligning the thin plate | board material 12, and operation is complicated.

  The present invention has been made in view of such a problem, and has excellent joint strength, and friction stir welding capable of joining metal materials having different thicknesses without generating burrs or the like at the joint. It aims to provide a method.

The friction stir welding method according to the present invention uses a joining tool provided with a cylindrical shoulder portion and a pin portion coaxially formed on the end surface of the shoulder portion and having a smaller diameter than the shoulder portion. And the step of abutting the second member thicker than the first member, and the abutting portion while rotating the joining tool by bringing the pin portion into contact with the abutting portion of the first member and the second member A step of causing the pin portion to enter the abutting portion by pressing toward the portion, and moving the joining tool at a forward angle θ so that the pin portion passes the abutting surface while rotating the joining tool. A step of joining the first member and the second member to each other, wherein the thickness of the first member is t ₁ , the thickness of the second member is t ₂ , and the shoulder Part diameter When the d, advancing angle θ is characterized by satisfying Equation 1 below.

  As a result of diligent experimental research on the friction stir welding method, the present inventors have found that plate members having different plate thicknesses are joined together by friction stir welding by causing the pin portion to enter from a surface with a step. It has been found that if the advancing angle is the same as when the members are joined, the difference thickness joint cannot be filled with sufficient stirring metal. Therefore, in the present invention, the lower end portion of the shoulder portion is caused to enter the second member by setting the advancing angle θ of the pin portion within the range of the above mathematical formula 1. Since the shoulder portion is rotating in the same manner as the pin portion, plastic flow also occurs in the portion where the shoulder portion enters, and the gap of the joint portion is filled.

  The first and second members are made of, for example, aluminum or an aluminum alloy.

  According to the friction stir welding method of the present invention, the welding tool is inclined to the thin plate side by adjusting the advance angle so that the end of the shoulder portion is located in the range from half the plate thickness to the upper surface of the thin plate. The members with different thicknesses can be butt-joined by the friction stir welding method without causing the members to be inclined or disposed, so that the increase in the shaft of the processing machine and the complexity of the restraining jig, etc. It will be resolved. Further, by joining by the friction stir welding method of the present invention, an excellent butt joint having excellent joint strength and no burr can be obtained.

Hereinafter, a friction stir welding method according to an embodiment of the present invention will be specifically described with reference to the accompanying drawings. Fig.1 (a) is a side view which shows the friction stir welding method of this embodiment, FIG.1 (b) is sectional drawing by the AA line shown to Fig.1 (a). 2A is a cross-sectional view showing a welding tool used in the friction stir welding method according to the embodiment of the present invention, and FIG. 2B is a cross-sectional view showing a state in which the welding tool is inserted into a member. FIG. In the friction stir welding method of the present embodiment, a thin plate material 3 having a thickness t ₁ and a thick plate material 4 thicker than the thin plate material 3 are attached to the end surface of the columnar shoulder portion 1 having a diameter d. It joins using the joining tool which is coaxial with the part 1 and provided with the pin part 2 with a smaller diameter than the shoulder part 1. As a material of the pin part 2 in this joining tool, a material harder than the thin plate material 3 and the thick plate material 4 which are members is used. In addition, although the thin plate material 3 and the thick plate material 4 in this embodiment can use an aluminum plate, an aluminum alloy plate, etc., for example, this invention is not limited to this and friction stir welding is possible. Any metal plate may be used.

  First, the joining surfaces of the thin plate material 3 and the thick plate material 4 are brought into contact with each other, and are arranged so that their bottom surfaces are in the same plane. At this time, a step is generated on the upper surface. Next, the pin portion 2 is brought into contact with the abutting portion of the thin plate material 3 and the thick plate material 4 while being inclined at an angle θ in the direction opposite to the joining direction 5, and pressed toward the abutting portion while rotating the joining tool. As a result, the pin portion 2 is caused to enter the butt portion. At this time, the end portion of the shoulder portion 1 is also pushed into the thick plate material 4. The pushing amount of the shoulder portion 1 is preferably from the half of the level difference formed by the thin plate material 3 and the thick plate material 4 to the upper surface of the thin plate material 3 and indicates the pushing amount (d / 2) × sin θ. Is within the range of Equation 1 above. If the pushing amount of the shoulder portion 1 is equal to or less than half the thickness difference between the thin plate material 3 and the thick plate material 4, a joint is not formed. Further, when the shoulder portion 1 is pushed into the thin plate material 3, the amount of generation of burrs or the like increases.

  Then, the joining tool is rotated and moved at the advance angle θ so that the pin portion 2 passes through the abutting surface. At this time, since the periphery of the pin portion 2 and the shoulder portion 1 is heated by frictional heat and plastic flow occurs, the metal in front of the pin portion 2 and the shoulder portion 1 is moved by moving the pin portion 2 along the abutting surface. While moving in a plastic flow, they move backward to form a joint structure.

Further, the length L of the pin portion 2 is preferably shorter than (t ₂ / cos θ). If the length L of the pin portion 2 is longer than (t ₂ / cos θ), the pin portion 2 penetrates the member. Further, when the length L of the pin portion 2 is set to (t ₂ / cos θ), an unstirred portion in the joint portion can be eliminated, but the pin portion 2 may penetrate the member. Therefore, it is preferable that the length L of the pin portion 2 be shorter by about 0.1 to 0.2 mm than (t ₂ / cos θ).

  In the present embodiment, the advancing angle θ when the members (thin plate material 2 and thick plate material 3) having different thicknesses are joined by friction stir welding by causing the pin portion 2 to enter from a surface with a step is set in the range of the above formula 1. To be inside. As a result, the end portion of the shoulder portion 1 is pushed into the thick plate member 3, and the plastic flow is generated in the portion into which the shoulder portion 1 has entered as well as the periphery of the pin portion 2 to form a joint structure. As a result, it is possible to produce a joint with excellent joint strength and no burrs at the joint even if the pin part 2 is not inclined and entered as in the conventional friction stir welding method.

  Examples of the present invention will be specifically described below in comparison with comparative examples that are out of the scope of the present invention. As an example of the present invention, a joining tool in which the diameter of the shoulder portion 1 is 12.5 mm is used, and the advance angle θ is 3 ° (Comparative Example 1), 6 ° (Example 1), 9 ° (Example 2). The butt joint of a 1.0 mm thick aluminum alloy plate and a 2.0 mm thick aluminum alloy plate was produced. FIGS. 3A to 3C are schematic diagrams showing the advance angle in the friction welding method of the embodiment of the present invention. Table 1 shows the composition of the aluminum alloy (A5182P-O) used in this example. About the joint of these aluminum alloy plates, observation of a junction part and a tensile test were done. The results are shown in Table 2.

  As shown in Table 2, the butt joint of Comparative Example 1 whose advancing angle is 3 ° smaller than the range of the present invention has a small amount of metal that plastically flows, and therefore has a linear defect that opens to the surface. Remained. Therefore, it was a level which cannot be used as a joint. On the other hand, in the butt joint of Example 1 having an advance angle of 6 °, the amount of metal that plastically flows was ensured, so that a good joint was formed. Moreover, in the butt joint of Example 2 whose advancing angle is 9 °, sufficient metal plastic flow was obtained although the formation of the joint portion was somewhat disturbed. Further, in the tensile test, the joint of Comparative Example 1 having an advancing angle of 3 ° did not provide sufficient joint strength. On the other hand, the butt joints of Examples 1 and 2 with the advance angles of 6 ° and 9 ° were broken on the thin plate material side, and exhibited excellent bonding strength.

  From the above results, when joining members with different thicknesses by the friction stir welding method, the advance angle θ is set so that the end of the shoulder portion of the rotating member is located on the thin plate side from half of the step formed by the members. As a result, it was found that a good bonded state can be obtained.

(A) is a side view which shows the friction stir welding method of embodiment of this invention, (b) is sectional drawing by the AA line shown to (a). (A) is sectional drawing which shows the joining tool used with the friction stir welding method of embodiment of this invention, (b) is sectional drawing which shows the state by which the joining tool shown to (a) was inserted in the member. is there. (A) thru | or (c) is a schematic diagram which shows the advance angle in the friction welding method of the Example of this invention. (A) is sectional drawing which shows the friction stir welding method of patent document 1, (b) is sectional drawing which shows the friction stir welding method of patent document 2. FIG. It is sectional drawing which shows the friction stir welding method of patent document 3.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1; Shoulder part 2 and 11a; Pin part 3 and 12; Thin board material 4 and 13; Thick board material 5; Joining direction 11; Joining tool 14;

Claims (2)

Using a joining tool provided with a cylindrical shoulder portion and a pin portion having a smaller diameter than the shoulder portion formed coaxially on the end surface of the shoulder portion, the first member and the second member thicker than the first member are used. The step of abutting the member with the first member and the pin portion by contacting the pin portion with the abutting portion of the first member and the second member and pressing the pin against the abutting portion while rotating the joining tool The first member and the first member by moving the joining tool at a forward angle θ so that the pin part passes through the abutting surface while rotating the joining tool. A step of joining the two members, and when the thickness of the first member is t ₁ , the thickness of the second member is t ₂ , and the diameter of the shoulder portion is d, the advancing Angle θ is the following number Friction stir welding method characterized by satisfying.

The friction stir welding method according to claim 1, wherein the first and second members are made of aluminum or an aluminum alloy.

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