JP2008137075A - Method of joining metallic material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of joining metallic material, a method by which friction stir welding can be performed while the rear side of a joined part is efficiently heated. <P>SOLUTION: With a joining tool 18 inserted from the upside of the joint part 16, a heating rear plate 28 is brought into contact with the joint 16 from its downside. The joining tool 18 is rotated in its rotating direction 24 side, with the heating rear plate 28 rotated in its rotating direction 32 side which is reverse from the rotating direction 24 side of the joining tool. The revolving speed of the joining tool 18 and the heating rear plate 28 are controlled in the manner that they mutually cancel out torques imparted to metallic materials 12, 14 respectively. The joining tool 18 and the heating rear plate 28 are moved along the longitudinal direction of the joint 16 while made to face oppositely. The heating rear plate 28 directly heats the joint 16 by frictional heat, with the joining tool 18 stirring the metal of the joint 16, so that the metallic materials 12, 14 are joined to each other. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for joining metal materials, and more particularly to a method for joining metal materials that performs friction stir welding while heating a joint.

In a conventional method for joining metal materials, a technique for joining metal materials by friction stir welding (FSW = Friction Stir Welding) is known. In friction stir welding, the metal materials to be joined are made to face each other at the joining portion, a probe provided at the tip of the joining tool is inserted into the joining portion, and the joining tool is moved while rotating along the longitudinal direction of the joining portion. Then, the two metal materials are joined by causing the metal material to plastically flow by frictional heat. Friction stir welding, as a general rule, can obtain good joint strength, but on the opposite side (rear side) of the part where the probe is inserted (rear side), heat input is insufficient, resulting in poor bonding. There is a risk of insufficient bonding strength. Therefore, Patent Document 1 describes a technique in which a heating unit including a heater wire is provided on the back surface side of the joint portion and the friction stir welding is performed while heating the back surface side of the joint portion.
JP 2002-79383 A

  However, even if a heater is provided and the back side of the joint is heated as in the above technique, the above technique indirectly causes the heated heating means to contact the back side of the joint so that it is indirectly applied to the back side of the joint. In order to transmit heat, the heat input to the back side of the joint becomes insufficient, and eventually the joint strength of the joint may be insufficient.

  In view of such circumstances, the present invention intends to provide a metal material joining method capable of performing friction stir welding while efficiently heating the back surface side of the joint.

  In the present invention, two metal materials are made to face each other at a joint portion, a rod-shaped joining tool is inserted from one side of the joint portion, and a heating back plate is brought into contact with the other side of the joint portion so as to face the joining tool. And joining the two metal materials by rotating the joining tool and the heating back plate.

  According to this configuration, a rod-shaped joining tool is inserted from one side of the joining portion, and the heating back plate is brought into contact with the other side of the joining portion so as to face the joining tool. Therefore, the metal material can be friction stir welded while the back side of the joint is heated only by the frictional heat between the heated back plate and the material to be joined. Since the back side of the joint is directly heated by friction with the heating back plate, the back side of the joint can be heated more efficiently than in the case where heat is indirectly applied by means such as a heater. it can.

  In the metal material joining method of the present invention, the rotating tool is rotated along the longitudinal direction of the joint portion while rotating, and the rotating tool rotated at the joint portion is rotated at that position without being moved. Including the case of continuing. Also, in this specification, “friction stir welding” means (1) end portions of plate-like metal materials are brought into contact with each other to form a joint portion, and the rotary tool is moved while rotating along the longitudinal direction of the joint portion. Friction stir welding that joins metal materials together, (2) Spot friction stir welding where the ends of plate-shaped metal materials are butted together to form a joint, and the rotary tool is rotated without moving at the joint. (Spot FSW), (3) Spot friction stir welding where metal materials are overlapped at the joint, a rotating tool is inserted into the joint, and the rotating tool is rotated without moving at that location to join the metal materials together (4) Friction stir welding in which metal materials are overlapped at the joint, a rotary tool is inserted into the joint, and the rotary tool is moved while rotating along the longitudinal direction of the joint to join the metal materials together Of (1 Includes four aspects and combinations of these - (4).

  In this case, it is preferable to rotate the joining tool and the heating back plate in opposite directions.

  According to this configuration, the stirring efficiency is improved by rotating the joining tool and the heating back plate in opposite directions. Moreover, it becomes easy to cancel the torque which a joining tool and a heating backplate give to a metal material, and the effort which hold | maintains a metal material can be reduced.

  In this case, it is more preferable to rotate the bonding tool and the heating back plate while controlling the rotation speeds of the bonding tool and the heating back plate so that the torques applied to the two metal materials by the bonding tool and the heating back plate can cancel each other.

  According to this configuration, since the joining tool and the heating back plate are rotated so that the torques applied to the two metal materials by the joining tool and the heating back plate mutually cancel each other, the labor for holding the metal material is further increased. Can be reduced.

  According to the metal material joining method of the present invention, the friction stir welding can be performed while efficiently heating the back surface side of the joint.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a perspective view showing a stationary joining apparatus according to a first embodiment of the present invention, and FIG. 2 is a diagram showing a basic concept of a metal material joining method according to the first embodiment of the present invention. It is. As shown in FIG. 1, the joining apparatus 10 a of this embodiment includes a joining tool 18, a joining tool driving unit 22, a heating back plate 28, a heating back plate driving unit 30, and a control unit 36 on a base 38. As shown in FIG. 2, the joining apparatus 10 a of the present embodiment is capable of friction stir welding the metal materials 12 and 14 with the joining tool 18 while heating the back side of the joining portion 16 with the heating back plate 28. It is configured.

The joining tool 18 is a member for friction stir welding of the metal materials 12 and 14, has a substantially cylindrical shape, and has a substantially columnar probe 20 having a smaller diameter than the main body at the tip. Note that a probe is not always necessary, and in some cases, a substantially cylindrical joining tool having no probe may be used. The material of the joining tool 18 is, for example, tool steel such as SKD61 steel standardized by JIS, cemented carbide made of tungsten carbide (WC) or cobalt (Co), ceramics such as Si ₃ N ₄ , or It can be made of a refractory metal such as W, Mo, iridium (Ir), an iridium alloy or hafnium (Hf). The joining tool 18 forms a predetermined angle with respect to the vertical direction of the surfaces of the metal materials 12 and 14 as necessary, for example, an angle of 0 to 5 °.

  The joining tool driving unit 22 is a member that rotates the joining tool 18 in the joining tool rotation direction 24 side and moves the joining tool 18 along the joining tool moving direction 26. The welding tool driving unit 22 is driven by a control signal from the control unit 36, and the rotation speed and movement speed of the welding tool 18 are controlled by the control unit 36.

  The heating back plate 28 rotates while abutting on the back surface side of the joint portion 16 and heats the joint portion 16 by frictional heat. The heating back plate 28 has a flat plate shape, for example, a square plate or a circular plate, or a rectangular parallelepiped shape or a substantially cylindrical shape. The heating back plate 28 has a diameter larger than that of the joining tool 18 in order to apply frictional heat to a wide range of the joining portion 16 and to reduce the number of revolutions necessary for canceling out the torque of the joining tool 18 as will be described later. Have. Specifically, the diameter (or one side) of the heating back plate 28 is 1 to 7 times the diameter of the welding tool 18, and more preferably 2 to 5 times. Alternatively, the diameter (or one side) of the heating back plate 28 may be 15 to 25 times the diameter of the welding tool 18 in order to apply frictional heat over a wide range.

The material of the heating back plate 28 is, for example, tool steel such as SKD61 steel standardized by JIS, cemented carbide made of tungsten carbide (WC), cobalt (Co), or Si, similar to the joining tool 18. _{It can be made} of ceramics such as ₃ N ₄ , iridium (Ir), iridium alloy or hafnium (Hf). The heating back plate 28 forms a predetermined angle with respect to the vertical direction of the back surfaces of the metal materials 12 and 14 as necessary, for example, an angle of 0 to 5 °. As shown in FIG. 2, the heating back plate 28 is disposed so as to face the bonding tool 18 and the rotation axis of the bonding tool 18 and the rotation axis of the heating back plate 28 are on the same straight line. However, according to the case, you may arrange | position so that the rotating shaft of the joining tool 18 and the rotating shaft of the heating back plate 28 may make a predetermined angle. Moreover, you may arrange | position so that the rotating shaft of the joining tool 18 and the rotating shaft of the heating back plate 28 may be shifted by a predetermined distance. 1 and 2, the heating back plate 28 has a substantially cylindrical shape, but may have a rectangular column shape such as a quadrangular column or a hexagonal column, or other shapes. Further, the tip of the heating back plate 28 does not necessarily have to be a flat surface, and may be a concave surface or a convex surface.

  The heating back plate drive unit 30 rotates the heating back plate 28 in the heating back plate rotation direction 32 side and moves it along the welding tool movement direction 34. The heating back plate drive unit 30 is driven by a control signal from the control unit 36, and the rotation speed and movement speed of the heating back plate 28 are controlled by the control unit 36.

  The control unit 36 gives control signals to the welding tool driving unit 22 and the heating back plate driving unit 30. The control unit 36 controls the bonding tool 18 and the heating back plate 28 to move along the longitudinal direction of the bonding portion 16 while facing each other. Further, the control unit 36 controls the rotation of the joining tool 18 and the heating back plate 28 so that the torques applied to the metal materials 12 and 14 by the joining tool 18 and the heating back plate 28 cancel each other.

  In the present embodiment, a light alloy material containing Al or the like can be applied as the metal materials 12 and 14, but in the present embodiment, the heating back plate 28 functions to increase the back surface from the front surface side of the joint portion 16. Since heat can be applied more uniformly to the side, it is preferable to apply a high melting point material having a melting point of 1000 ° C. or higher, or a steel-based material containing Fe or the like. Specifically, for example, carbon steel, alloy steel, austenitic stainless steel such as SUS304, SUS301L, and SUS316L, ferritic stainless steel such as SUS430, or duplex stainless steel can be applied. Alternatively, as the metal materials 12 and 14, different materials can be applied instead of the same materials. Specifically, for example, joining of carbon steels such as joining of SS400 and S45C, joining of carbon steel and stainless steel such as joining of SS400 and SUS304, joining of light alloys such as joining of A5083 and AZ41, etc. The joining method of the present embodiment can perform joining, joining of aluminum alloys, which are non-heat treated materials such as A5083 having a large plate thickness, and joining of non-heat treated materials and heat treated materials such as joining of A5083 and A6N01. . In the example of FIGS. 1 and 2, the welding tool 18 and the heating back plate 28 are moved with respect to the fixed metal materials 12, 14. The metal materials 12 and 14 may move with respect to the heating back plate 28.

  At the time of joining, as shown in FIG. 2, the metal materials 12 and 14 are made to face each other at the joining portion 16, the probe 20 of the joining tool 18 is inserted from above the joining portion 16, and the heating back plate 28 is placed below the joining portion 16. Contact from the side. By the control signal from the control unit 36, the welding tool driving unit 22 rotates the welding tool 18 in the welding tool rotation direction 24 side, and the heating back plate driving unit 30 rotates the heating back plate 28 in the heating back plate rotation direction 32 side. Let me. The welding tool rotation direction 24 and the heating back plate rotation direction 32 are opposite directions. Further, the control unit 36 controls the rotational speeds of the welding tool 18 and the heating back plate 28 so that the torques applied to the metal materials 12 and 14 by the welding tool 18 and the heating back plate 28 are mutually offset. . In the example of FIG. 2, since the diameter of the heating back plate 28 is larger than that of the bonding tool 18, the rotation speed of the heating back plate 28 is set to be lower than the rotation speed of the bonding tool 18. The torques applied to the metal members 12 and 14 by the plates 28 can be canceled with each other.

  In accordance with a control signal from the control unit 36, the welding tool driving unit 22 and the heating back plate driving unit 30 make a predetermined bonding speed along the longitudinal direction of the bonding unit 16 while facing the bonding tool 18 and the heating back plate 28, respectively. Move with. The heating back plate 28 heats the joint portion 16 by frictional heat, and the joining tool 18 plastically flows and stirs the metal of the joint portion 16, whereby the metal materials 12 and 14 can be joined. When the joining tool 18 and its probe 20 and the heating back plate 28 are worn out by use, the joining can be continued by appropriately replacing them.

  In the present embodiment, the joining tool 18 is inserted from the front surface side of the joining portion 16, and the heating back plate 28 is brought into contact with the back surface side of the joining portion 16 so as to face the joining tool 18. 28, the metal members 12 and 14 can be friction stir welded while heating the back side of the joint 16. Since the back surface side of the joint portion 16 is directly heated by friction with the heating back plate 28, the back surface side of the joint portion 16 is heated more efficiently than when heat is indirectly applied by means such as a heater. can do. As a result, the degree of agitation is equal between the front surface side and the back surface side of the joint, and defects are less likely to occur, and a joint with stable and high joint strength can be created. The method of the present embodiment is particularly effective when joining refractory metals such as carbon steel and stainless steel. In addition, a joint having high strength can be created even at a higher joining speed.

  In the present embodiment, the welding tool 18 and the heating back plate 28 are rotated in opposite directions so that the torque applied to the metal materials 12 and 14 by the welding tool 18 and the heating back plate 28 cancel each other. Therefore, in a friction stir welding that requires a large-scale fixing tool or the like to hold the workpiece due to the torque originally applied to the workpiece from the welding tool, the workpiece is held by a simple method. be able to. Furthermore, since the joining tool 18 and the heating back plate 28 are rotated in the reverse direction, the stirring efficiency is improved and the occurrence of kissing bonds, which are closely cracked surfaces having no bonding force, can be prevented.

  Furthermore, in the present embodiment, the heating back plate 28 rotates while contacting the back side of the joint portion 16, and the frictional force between the heating back plate 28 and the joint portion 16 becomes small calculated by the dynamic friction coefficient. The heating back plate 28 can be moved along the joint 16 with a smaller force than when a fixed heater or the like is brought into contact with the joint 16.

  In addition, the joining method of the metal material of this embodiment can be applied to the joining of the side panel and the roof of the railway vehicle structure 100 as shown in FIG. Further, the metal material joining method of the present embodiment can be applied to joining of the body plates of the tank truck 102 as shown in FIG. Furthermore, the joining method of the metal material of this embodiment is applicable to joining of the pallet 104 of a three-dimensional parking apparatus, as shown in FIG. As shown in FIG. 8, it can be applied to the joining of the outer plate and the inner wall of the container 106.

  FIG. 3 is a perspective view showing a portable joining apparatus according to the second embodiment of the present invention. As shown in FIG. 3, the portable joining device 10b of this embodiment includes substantially the same components as the stationary joining device 10a of the first embodiment, but the size of the device can be carried by an operator. This is different from the stationary joining apparatus 10a of the first embodiment in that the strap 40 is provided so as to be held by an operator. The portable joining device 10b of the present embodiment rotates the joining tool 18 and the heating back plate 28 in opposite directions so that the torques applied to the metal material by the joining tool 18 and the heating back plate 28 cancel each other. Therefore, a large force is not required for holding the portable joining device 10b and the workpiece, and it is possible to perform the work manually without a large-scale fixing tool. For this reason, it becomes a very useful thing for work, such as repair of a narrow part.

  FIG. 4 is a diagram showing a basic concept of a metal material joining method according to the third embodiment of the present invention. As shown in FIG. 4, in this embodiment, the metal materials 12 and 14 are overlapped at the joint portion 16, the joining tool 18 is inserted into the joint portion 16 through the metal material 12, and the joining tool 18 is rotated to rotate the metal material. 12 and 14 are joined together. Similarly, the friction stir welding can be performed also in the wide joint portion 16 by sequentially inserting and rotating the welding tool 18 in other locations.

  In addition, the joining method of the metal material of this invention is not limited to above-described embodiment, Of course, various changes can be added within the range which does not deviate from the summary of this invention. For example, in the above-described embodiment, the description has been made centering on a mode in which the joining tool and the heating back plate are rotated in opposite directions, but the present invention is not limited to this, and the joining tool and the heating back plate are in the same direction. In the case where it is possible to obtain a joint portion that is better when rotated, both may be rotated in the same direction, and such an aspect is also included in the scope of the present invention.

  Moreover, although the said embodiment demonstrated centering on the aspect which joins two metal materials, this invention can also be applied to modification | reformation of a metal material, without joining a metal material. For example, the metal material can be reformed by plastic flow by bringing the joining tool and the heating back plate into contact with one metal material so as to face each other and rotating the joining tool and the heating back plate.

(Experimental example 1)
The plate material of SUS304, which is stainless steel, was joined under the conditions shown in FIG. On the other hand, the joining tool 18 was inserted only from the surface side of the joining portion 16 on the fixed surface plate, and joining was performed without using the rotating heating back plate 28 (normal joining). The other was joined by the joining method of the present invention using the joining tool 18 and the heated back plate 28 (double-sided joining).

  FIG. 10A is a view showing a longitudinal section of the joint 16 in the normal single-side joining of stainless steel, and FIG. 10B is an enlarged view of FIG. 10A. Moreover, Fig.11 (a) is a figure which shows the longitudinal cross-section of the junction part 16 in the double-sided joining of stainless steel, and FIG.11 (b) is an enlarged view of Fig.11 (a). As shown in FIG. 10 (b), it can be seen that in the joint portion 16 by normal joining, a close crack surface having no bonding force called a kissing bond is formed on the back surface side. On the other hand, as shown in FIG. 11B, it can be seen that no kissing bond is generated on the back surface side in the joint portion 16 by the double-sided joining of the present invention.

  FIG. 12 is a graph comparing the tensile strengths of normal single-sided bonding and double-sided bonding in stainless steel. As shown in FIG. 12, it can be seen that the tensile strength in normal bonding is 684 MPa, whereas the tensile strength in double-sided bonding is greatly improved to 734 MPa.

(Experimental example 2)
A6N01, which is an aluminum alloy, was joined under the conditions shown in FIG. On the other hand, the joining tool 18 was inserted only from the surface side of the joining portion 16 on the fixed surface plate, and joining was performed without using the rotating heating back plate 28 (normal joining). The other was joined by the joining method of the present invention using the joining tool 18 and the heating back plate 28 and changing the rotational speed of the heating back plate 28 (double-sided joining).

  FIG. 14 (a) is a view showing a longitudinal section of a joint in normal single-sided joining of an aluminum alloy, and FIG. 14 (b) is an enlarged view of FIG. 14 (a). FIG. 15A is a view showing a longitudinal section of a joint in double-sided joining of an aluminum alloy, and FIG. 15B is an enlarged view of FIG. 15A. As shown in FIG. 14B, it can be seen that the bonded portion 16 by normal bonding has a closely cracked surface that does not have a bonding force called “kissing bond” on the back surface side. On the other hand, as shown in FIG. 15B, it can be seen that no kissing bond is generated on the back surface side in the joint portion 16 by the double-sided joining of the present invention.

  FIG. 16 is a graph comparing the tensile strengths of normal single-sided bonding and double-sided bonding in aluminum alloys. As shown in FIG. 16, it can be seen that the tensile strength of double-sided bonding is greatly improved at any rotational speed of the heating back plate 28 compared to the tensile strength of normal bonding.

It is a perspective view which shows the stationary joining apparatus which concerns on 1st Embodiment of this invention. It is a figure which shows the basic concept of the joining method of the metal material which concerns on 1st Embodiment of this invention. It is a perspective view which shows the portable joining apparatus which concerns on 2nd Embodiment of this invention. It is a figure which shows the basic concept of the joining method of the metal material which concerns on 3rd Embodiment of this invention. It is a perspective view which shows the example which applied the joining method of the metal material which concerns on 1st Embodiment to the side surface board and roof of a railway vehicle. It is a perspective view which shows the example which applied the joining method of the metal material which concerns on 1st Embodiment to the trunk | drum of a tank truck. It is a perspective view which shows the example which applied the joining method of the metal material which concerns on 1st Embodiment to the pallet of a multilevel parking apparatus. It is a perspective view which shows the example which applied the joining method of the metal material which concerns on 1st Embodiment to the outer plate | board and inner wall of a container. 4 is a table showing joining conditions of stainless steel according to Experimental Example 1. (A) is a figure which shows the longitudinal cross-section of the junction part in the normal single-sided joining of stainless steel, (b) is an enlarged view of (a). (A) is a figure which shows the longitudinal cross-section of the junction part in the double-sided joining of stainless steel, (b) is an enlarged view of (a). It is the graph which compared the tensile strength of the normal single-sided joining and double-sided joining in stainless steel. 6 is a table showing joining conditions of an aluminum alloy according to Experimental Example 1. (A) is a figure which shows the longitudinal cross-section of the junction part in the normal single-sided joining of aluminum alloy, (b) is an enlarged view of (a). (A) is a figure which shows the longitudinal cross-section of the junction part in the double-sided joining of an aluminum alloy, (b) is an enlarged view of (a). It is the graph which compared the tensile strength of the normal single-sided joining and double-sided joining in an aluminum alloy.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10a ... Stationary joining apparatus, 10b ... Portable joining apparatus, 12, 14 ... Metal material, 16 ... Joining part, 18 ... Joining tool, 20 ... Probe, 22 ... Joining tool drive part, 24 ... Joining tool rotation direction, 26 DESCRIPTION OF SYMBOLS Joining tool movement direction 28 ... Heating back plate, 30 ... Heating back plate drive part, 32 ... Heating back plate rotation direction, 34 ... Heating back plate movement direction, 36 ... Control part, 38 ... Base part, 40 ... Strap, 100 ... Railroad vehicle structure, 102 ... Tank truck, 104 ... Pallet, 106 ... Container.

Claims (3)

  Two metal materials are made to face each other at the joint, a rod-like joining tool is inserted from one side of the joint, and a heating back plate is brought into contact with the other side of the joint so as to face the joining tool. The metal material joining method of rotating the joining tool and the heating back plate to join the two metal materials.   The metal material joining method according to claim 1, wherein the joining tool and the heating back plate are respectively rotated in opposite directions.   The rotation of the joining tool and the heating back plate is controlled while controlling the rotation speed of the joining tool and the heating back plate so that each of the joining tool and the heating back plate cancels each other the torque applied to the two metal materials. Metal material joining method.