JP2006167793A - Friction stir spot welding method and equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a friction stir spot welding method and friction stir spot welding equipment for performing the friction stir spot welding to soften and stir works consisting of a plurality of overlapped metal plates with the friction heat generated by the rotation of a welding tool and a pin, which realize reliable welding free from any improper welding or insufficient strength between the metal plates, and enable pin holes to be filled and the surface to be relatively flattened. <P>SOLUTION: A tapering pin is used, in which the shape of the pin 2 arranged on a distal end side of a welding tool 1 in a retractable manner has at least one stepped part 4. While a shoulder face of the rotating welding tool is abutted on an upper face of a work, the pin is pressed and rotated to soften the work, and allowed to enter the overlapped metal plates while stirring the softened work. The advancement and retraction of the pin are controlled so that the stepped part on the distal end side of the pin is not allowed to enter the overlapped metal plates in the first metal plate 6 from the distal end of the pin, but located in the second metal plate 5, and subsequently, the stepped part is successively located one by one in the upper ranked metal plates. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a friction stir spot welding method and apparatus for softening and agitating and joining a material to be joined such as aluminum and its alloy made of a plurality of stacked metal plates by frictional heat generated by rotation of a welding tool and a pin. It is about.

  Conventionally, a friction stir spot welding method and apparatus for softening and agitating and joining a workpiece made of two metal plates by friction heat generated by rotation of a jig body as a joining tool and a shaft as a pin, Use a pin with a cylindrical shape that can be projected and retracted on the tip side of the welding tool, and with the shoulder surface of the rotating welding tool in contact with the upper surface of the object to be joined Is pressed and rotated to soften and stir the object to be intruded into the stacked metal plate (for example, see Patent Document 1).

  Also, multiple steps are formed in the rotating tool, and one step is positioned in each metal plate except for the lowest metal plate of the object to be joined consisting of multiple stacked metal plates. There is one in which the object to be joined is softened and agitated by rotation of the tool and joined (for example, see Patent Document 2).

JP 2003-305576 A JP 2002-292478 A

  By the way, in the above-mentioned conventional technology, in the former, since the shape of the pin is a simple columnar shape, it is possible to expand the stirring portion by pressing the raised portion with a shoulder surface by stirring with a press-fit pin, This is effective for joining two stacked metal plates. For example, in the case of joining three stacked metal plates, the maximum pressing force between the uppermost metal plate and the lower metal plate and the stirring force by the shoulder surface and the pin are the highest. The frictional heat is generated in the upper metal plate and the metal structure flows toward the lower metal plate, but only the frictional heat and stirring force generated around the press-fit pins are only applied to the intermediate metal plate and the lowermost metal plate. It is. Therefore, the flow of the metal structure from the intermediate metal plate toward the lowest metal plate hardly occurs on the joint surface between the intermediate metal plate and the lowest metal plate. Further, in the case of an aluminum plate, the metal plate may be joined with an oxide film remaining on the surface. For these reasons, in this conventional method and apparatus, it is likely to cause poor bonding and insufficient strength between the metal plate other than the uppermost metal plate and the metal plate immediately below it. There is a problem that the application is not suitable for joining.

  Further, in the above-described conventional technique, in the latter, since one step portion is positioned in each metal plate except for the lowest metal plate of the object to be joined made of a plurality of stacked metal plates, a plurality of stacked metal plates are provided. Although it can be applied to the joining of metal plates, the surface of the top metal plate cannot be always pressed because there is no shoulder surface where the pins appear and disappear like the former. -If the steel plate cannot be optimally handled, and there is a difference in the material of each metal plate even in the same number of stacked metal plates, there is a difference in the flow of the softened and agitated metal structure and reliable bonding In addition, there is a problem that it is difficult to make up for the holes of the traces extracted from the rotating tool and to flatten the surface.

  The present invention has been made in view of such problems of the prior art, and the object of the present invention is to form a plurality of stacked metal plates by frictional heat generated by the rotation of the joining tool and the pin. Friction stir spot welding that softens and agitates the workpieces to be joined, ensures reliable joining without poor bonding between metal plates and lack of strength, and makes it possible to fill pin holes and relatively flatten the surface. An object of the present invention is to provide a friction stir spot welding method and apparatus.

  In order to achieve the above object, the friction stir spot welding method according to the present invention uses a tapered pin having a stepped portion with at least one step portion arranged so as to be able to protrude and retract on the tip side of the welding tool. With the shoulder surface of the welding tool to be in contact with the upper surface of the object to be joined, the pin is pressed and rotated to soften and agitate the object to be joined into the stacked metal plate while stirring the pin. The stepped parts are positioned in the second metal plate without entering the first metal plate counted from the tip of the pin, and the pins are arranged so that the stepped portions are sequentially placed one by one in the upper metal plate. Is characterized by being controlled in and out.

  The friction stir spot welding device according to the present invention includes a mechanism for rotating the joining tool and the pin simultaneously, and a mechanism for moving the pin in the axial direction with respect to the joining tool. The shape of the pin arranged so as to be able to appear and retract with respect to the shoulder surface on the front end side is a tapered pin having at least one step portion, and the pin can be controlled to appear and appear corresponding to the number of stacked metal plates. It is characterized by.

  In the friction stir spot welding method according to the present invention, the shoulder surface of the welding tool or each stepped portion is pressed from the upper metal plate toward the lower metal plate. The metal structure receives a force directed diagonally downward and outward by the combined force of the rotational force of the pin and the pressing force by the pressing, and the tissue flows and is integrated and joined. In addition, the oxide film formed on both surfaces of each joining member is also finely pulverized and softened and dispersed in the metal to make the joining surface and the structure in the vicinity thereof uniform. Furthermore, since the steps are pressed and agitated by each step directly above each metal plate, the plate has rigidity, and the upper metal plate softens and adheres even in the case of an object having a warp between the metal plates. . In addition, since the position of the stepped portion of the pin can be changed by adjusting the protruding amount of the pin with respect to the shoulder surface that is in contact with the upper surface of the object to be joined, it can cope with changes in the thickness and material of the metal plate, respectively. The shoulder surface that rotates when the pin is pulled out always presses the upper surface of the object to be joined, so that the trace of the pin hole can be compensated for when the pin is pulled out, and the upper surface of the object can be flattened eventually. .

  Moreover, in the friction stir spot welding device according to the present invention, the objects to be joined consisting of a plurality of stacked metal plates are securely and closely joined to each other, and a single pin can handle a plurality of types of stacked objects to be joined. It becomes a friction stir spot welding device.

  In the friction stir spot welding method according to the present invention, a tapered pin having at least one step portion is used so that the shape of the pin that can be projected and retracted on the tip side of the welding tool is used. With the shoulder surface in contact with the upper surface of the object to be joined, the pin is pressed and rotated to soften and agitate the object to be intruded into the stacked metal plate, and the step on the tip side of the pin is the tip of the pin. The pins are controlled so that they do not penetrate into the first metal plate and are located in the second metal plate, and the step portions are sequentially placed one by one in the upper metal plate. It is configured.

  In addition, the friction stir spot welding device according to the present invention includes a mechanism for simultaneously rotating the welding tool and the pin, and a mechanism for moving the pin in the axial direction with respect to the welding tool. The shape of the pin arranged so as to be able to appear and retract with respect to the shoulder surface on the tip side of the taper is a tapered pin having at least one step portion, and the pin can be controlled to appear and go according to the number of the stacked metal plates. , The configuration.

  FIG. 1 is a cross-sectional view of an essential part in which the friction stir spot joining method according to the present invention is performed for joining an aluminum alloy material made of two overlapping metal plates, and FIG. 2 is a friction stir according to the present invention. Sectional drawing of the principal part which implemented the spot joining method to the joining of the to-be-joined object of the aluminum alloy material which consists of three laminated metal plates, FIG. 3 is an apparatus suitable for implementing the friction stir spot joining method which concerns on this invention FIG. 4 is an explanatory diagram of a drive system for a joining tool and a pin.

  In FIG. 1, reference numeral 1 denotes a joining tool for friction stir spot joining, and a pin 2 is disposed at the front end side of the joining tool 1 so as to be able to appear and retract.

  The pin 2 is formed as a tapered pin having a most advanced pin portion 3 and one step portion 4, and the root side of the pin 2 is located in the joint tool 1, and the step portion 4 Can protrude from the shoulder surface 5 on the tip end side of the joining tool 1.

  6, 7, and 6 are aluminum alloy materials to be joined, which are two stacked metal plates. 6 is a lower metal plate on the first metal plate, and 7 is a higher metal plate on the second metal plate. It is piled up.

  In addition, 8 is a receiving frame which is arrange | positioned facing the said joining tool 1, and the said to-be-joined object is mounted, 9 shows a stirring part.

  FIG. 2 shows a case in which the joining tool 1 and the pin 2 shown in FIG. 1 are applied to the joining of an aluminum alloy material to be joined consisting of three stacked metal plates. An intermediate metal plate 10 is positioned and stacked between the upper metal plate 7.

  The drive system of the joining tool 1 and the pin 2 is, for example, as shown in FIG. 3, and a pressurizing motor 31 is fixed to a drive unit main body 30 provided on the wrist or stand of the robot. The pinning motor 33 and the agitating motor 34 are moved forward and backward simultaneously by the pressurizing member 32 connected to the output shaft of the pressurizing motor 31, thereby being attached to the agitating motor 34. The joint tool 1 and the pin 2 are moved forward and backward simultaneously.

  The pin 2 is connected to the pin pulling rod 35 connected to the output shaft of the pin pulling motor 33, and the pin 2 is joined to the joining tool by the forward / backward movement of the pin pulling rod 35. It moves forward and backward while sliding against 1.

  In FIG. 4, the most distal pin portion 3 on the distal end side of the pin 2 is disposed so as to be able to protrude and retract with respect to a shoulder surface 5 at the distal end of the joining tool 1, and the pin 2 extends in the direction of the central axis of the joining tool 1. It moves forward and backward in the bored hole 11. The rear end side of the pin 2 is screwed to the pin holding member 12.

  The rear end side of the pin holding member 12 is connected to the pin pulling rod 35 through a bearing device 21.

  Reference numeral 13 denotes a joining tool holder disposed between the output shaft 14 of the stirring motor 34 and the pin holding member 12. The joining tool holder 13 is connected to the joining tool 7 via a collet 15. The latter enlarged diameter portion 16 is integrally held. Reference numeral 17 denotes a nut for fastening the collet 15. By screwing the nut 17, the joint tool holder 13 and the joint tool 7 are surely integrated by the collet 15.

  A slide key 18 is disposed between the joint tool holder 13 and the pin holding member 12, and the pin holding member 12 is moved from the output shaft 14 of the agitating motor 34 by the slide key 18. It is possible to perform forward and backward movement by the pinning rod 35 while rotating by the rotational force of.

  The joining tool 1 is composed of a first-half narrow diameter portion 19 and a second-half enlarged diameter portion 16, and a shoulder surface 5 is formed on the front end surface of the joining tool 1 as described above. The hole 11 is formed in the direction of the central axis 19, the pin 2 is inserted into the hole 11, and the enlarged diameter portion 16 has a hollow chamber 20 whose rear end is open. A rear portion of the pin 2 and a front portion of the pin holding member 12 are accommodated in the chamber 20, and the pin 2 is screwed to the pin holding member 12.

  In the friction stir spot welding apparatus as described above, the agitation motor 34 and the pressurization motor 31 are driven, and the pressurization motor 31 drives the pin removal motor 33 and the agitation motor 34. At the same time, the advancing head moves toward the joining point of the object to be joined, and the joining tool 1 and the pin 2 are both rotated by the stirring motor 34. At this time, the tip of the pin 2 is located on the same plane as the shoulder surface 5 of the joining tool 1.

  When the shoulder surface 5 of the welding tool 1 contacts the upper surface of the uppermost metal plate 7 of the object to be joined by the pressurizing motor 31, the driving of the pressurizing motor 31 is stopped. The forward movement of the pin 2 and the joining tool 1 by the pressure motor 31 is stopped, but the pin 2 and the joining tool 1 continue to rotate by the stirring motor 34.

  Accordingly, the pinning motor 33 is driven, and the pin 2 advances while rotating through the pinning rod 35 and the pin holding member 12 and enters the workpiece.

  Then, when the pin 2 reaches a predetermined position, the driving of the pin removal motor 33 is stopped, but the shoulder surface 5 and the pin 2 are rotated by the rotation of the shoulder surface 5 and the pin 2 of the joining tool 1. A part of the object to be bonded is melted by rubbing against the object to be bonded, and this is agitated, and this melted object performs spot bonding of the object to be bonded.

  When the above-mentioned joining operation is performed, the pin pulling motor 33 is driven in reverse, and the pin 2 is pulled out from the joining point of the object to be joined and is at the same level as the shoulder surface 5 of the joining tool 1 or the same. Further, it is pulled out into the hole 11. During this time, since the agitating motor 34 is driven, the shoulder surface 5 of the rotating joining tool 1 operates so as to flatten the surface of the joining point of the object to be joined.

  It should be noted that the protrusion and depression of the pin 2 with respect to the shoulder surface 5 of the joining tool 1 independently drives the pin removal motor 33 irrespective of the drive of the pressurization motor 31 and the stirring motor 34. Therefore, it may be activated when necessary according to the state of the melt at the junction.

  By the way, in the friction stir spot welding according to the present invention, a tapered pin having one step portion 4 is used as the pin 2 to join the two metal plates 6 and 7 as shown in FIG.

  When the two metal plates 6 and 7 are joined, the shoulder surface 5 of the joining tool 1 is an object to be joined and is located on the upper surface of the upper metal plate 7, and the stepped portion 4 of the pin 2 is Depending on the level of the shoulder surface 5 or the thickness of the metal plate 7, the metal plate 7 is slightly intruded so that there is no step in the lower metal plate 6, and only the small-diameter tip pin portion 3 is present. It penetrates into the lower metal plate 6.

  Accordingly, the joint tool 1 and the pin 2 are in a rotating state in the state shown in the figure, and a pressing force is also exerted from the upper metal plate 7 toward the lower metal plate 6 by the shoulder surface 5 and the stepped portion 4. The metal structure immediately below the surface 5 and the stepped portion 4 receives a force directed obliquely downward and outward by the combined force of the rotational force of the pin 2 and the pressing force, and the structure flows and is integrated and joined. In addition, the oxide film formed on both surfaces of the metal plates 6 and 7 is also finely pulverized and softened and dispersed in the metal to make the joint surface and the structure in the vicinity thereof uniform. Furthermore, even in the case of a workpiece having a warp between the metal plates, the metal plate 7 is softened and closely adhered. In addition, since the position of the stepped portion 4 of the pin 2 can be changed by adjusting the protruding amount of the pin 2 with respect to the shoulder surface 5 in contact with the upper surface of the object to be joined, the thickness and material of the metal plate 7 can be changed. Further, since the shoulder surface 5 that rotates when the pin 2 is pulled out always presses the upper surface of the metal plate 7, the trace of the pin hole is made up with the withdrawal of the pin 2, and finally the metal plate 7. The upper surface can also be flattened.

  In order to join the three metal plates 6, 10, 7 as shown in FIG. 2, the pin 2 is a tapered pin having the same stepped portion 4 as described above.

  In this case, the shoulder surface 5 of the joining tool 1 is an object to be joined and is located on the upper surface of the upper metal plate 7, and the stepped portion 4 of the pin 2 is located in the intermediate metal plate 10. Depending on the thickness of the plate 7 or 10, the amount of intrusion is slightly adjusted inside the metal plate 10, and there is no step portion in the lower metal plate 6, and only the small-diameter tip pin portion 3 is lower. The metal plate 6 is invaded.

  Therefore, the upper metal plate 7 also exerts a pressing force toward the lower metal plate by the shoulder surface 5 of the joining tool 1 and the intermediate metal plate 10 by the stepped portion 4 of the pin 2, respectively. It is possible to expect substantially the same effect as the joining of two metal plates.

  Further, the pin 2 having one step portion 4 can be applied to the joining of two or three metal plates to form a general-purpose pin 2.

  FIG. 5 is a cross-sectional view of a main part in which the friction stir spot welding method according to the present invention is carried out for joining an aluminum alloy material to be joined comprising four laminated metal plates.

  In this embodiment, the pin 2 having two step portions is applied to join the four metal plates 7, 10, 22, 6. That is, the pin 2 is configured as a tapered pin having the most advanced pin portion 3 and step portions 4 and 23, and the root side of the pin 2 is located in the joint tool 1, and the step portion 4 , 23 can protrude from the shoulder surface 5 on the distal end side of the joining tool 1. In addition, 8 and 9 are the receiving frame and stirring part in which a to-be-joined object is mounted similarly to the previous Example.

  At the time of joining the objects to be joined, the shoulder surface 5 of the joining tool 1 is positioned on the upper surface of the uppermost metal plate 7 in the object to be joined, and the stepped portion 4 of the pin 2 is located inside the intermediate metal plate 10. The stepped portion 23 of the pin 2 is located in the intermediate metal plate 22, and the pin 2 is slightly inserted into the metal plate 22 depending on the thickness of the metal plate 7, 10 or 22. In the adjusted state, there is no step in the lowermost metal plate 6, and only the small-diameter tip pin portion 3 penetrates into the lower metal plate 6.

  Further, the operation and effect of this embodiment are not substantially different from those of the previous embodiment.

  In the above description, the pin removal motor 33 is used for the protrusion and retraction of the pin 2 with respect to the joining tool 1. For this protrusion and retraction, a commonly known machine such as an elastic body and an air cylinder is used. General means may be adopted.

FIG. 1 is an explanatory view in which a joining tool and a pin suitable for carrying out the present invention are applied to two metal plates. FIG. 2 is an explanatory view in which a joining tool and a pin suitable for carrying out the present invention are applied to three metal plates. FIG. 3 is an overall schematic configuration diagram of a friction stir spot welding apparatus suitable for carrying out the present invention. FIG. 4 is a configuration diagram of a driving mechanism for a joining tool and a pin suitable for carrying out the present invention. FIG. 5 is an explanatory view in which a joining tool and a pin suitable for carrying out the present invention are applied to four metal plates.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Joining tool 2 Pin 3 Pin part of the most advanced part 4,23 Step part 5 Shoulder surface of joining tool 6,7,10,22 Metal plate 31 Motor for pressurization (joint tool and pin (For simultaneous movement)
33 Pin removal motor (for pin movement)
34 Stirring motor (for simultaneous rotation of joining tool and pin)

Claims (2)

  In the friction stir spot welding method that softens and stirs the object to be joined consisting of multiple stacked metal plates by frictional heat generated by the rotation of the welding tool and the pin, it is arranged freely at the tip of the welding tool. Using a tapered pin with a pin shape having at least one stepped portion, the pin is pressed and rotated while the shoulder surface of the rotating joining tool is in contact with the upper surface of the object to be joined. While the object is softened and agitated, it penetrates into the stacked metal plate, and the step on the tip side of the pin counts from the tip of the pin and does not penetrate into the first metal plate and is located in the second metal plate. In the following, the friction stir spot welding method is characterized in that the pins are controlled so as to be sequentially positioned one by one in the upper metal plate. In a friction stir spot welding device that softens and stirs an object to be joined consisting of multiple stacked metal plates by frictional heat generated by the rotation of the welding tool and pin, and a mechanism in which the welding tool and pin rotate simultaneously. And a mechanism for moving the pin in the axial direction with respect to the joining tool, and the shape of the pin arranged so as to be able to protrude and retract with respect to the shoulder surface on the tip side of the joining tool has at least one step portion. A friction stir spot welding device, characterized in that the pin has a taper pin, and the pin can be controlled to appear and retract in accordance with the number of stacked metal plates.

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