JP4234291B2 - Joining tool for friction stir welding - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a welding tool for friction stir welding, which eliminates the generation of burrs remaining on the joining surface and can further improve the surface finish of the friction stir welding portion.
[0002]
[Prior art]
Friction stir welding itself that can butt-join aluminum materials (for example, panels) is well known in the art, and the outline thereof is as shown in FIGS.
That is, the panels P, P are brought into contact with each other, and the welding tool T is slowly advanced along the joining surface while being rotated at a high speed, so that the frictional heat between the pin 1 of the joining tool T and the joining surface of the panel is obtained. Further, the joining end portion is heated and plasticized by frictional heat between the shoulder portion 3 of the joining tool T and the joining surface, and joined.
When the panel P is made of aluminum having a thickness of 2 to 5 mm, a joining tool T in which the diameter of the pin 1 is 5 mm and the diameter of the tool body 2 is 15 mm is generally used.
The welding tool T moves forward in a state where it is slightly inclined rearward in the direction of travel (advance angle: empirically 3 degrees is appropriate). On the other hand, the lower end surface of the tool body 2, that is, the shoulder surface 3, is a concave conical surface. Therefore, when moving forward in a state where the vehicle is inclined forward, the rear portion in the traveling direction of the shoulder surface 3 slightly bites into the joint surface. For this reason, the surface portion plasticized by frictional heat is pushed out to the side of the joint surface by the rotation of the shoulder surface 3, and this is left as a fine burr on the panel surface. The trajectory through which the shoulder surface 3 passes is extremely smooth, but the surface to which the above-mentioned burr on the side is attached often needs to be smoothed by surface processing in preparation for coating.
[0003]
[Problems to be solved]
In view of this, the present invention aims to prevent burrs from remaining in the vicinity of the friction stir welding surface, and the joining tool captures the plasticized material that is plasticized by frictional heat and pushed outward by the joining tool. The problem is to devise the structure of the joining tool so that the plasticizing material does not become burred.
[0004]
[Measures taken to solve the problem]
The means taken to solve the above problem is that the outer peripheral portion of the shoulder surface of the welding tool is a conical surface convex downward with an inclination angle equal to the forward inclination angle for the friction stir welding tool that moves forward in a state of being inclined forward. It is.
[0005]
[Action]
In the state where the welding tool is set up vertically, the outer peripheral portion of the shoulder surface at the lower end of the welding tool is a conical surface convex downward, and becomes an inclined surface inclined at an angle equal to the advance angle with respect to the welding surface. Is inclined at a forward inclination angle, the rearward portion of the conical surface in the forward direction comes into contact with the joint surface in a state parallel to the joint surface of the workpiece.
The rear part in the traveling direction of the annular edge at the radially inner end of the downwardly convex conical surface (annular edge between the convex part of the shoulder above the central part of the shoulder) bites into the joining surface, and frictional heat The plasticized material on the surface of the joint portion plasticized in (1) is extruded outwardly of the joint surface by its rotational movement. However, since the rear portion in the forward direction of the conical surface is parallel to the joint surface of the workpiece and is tracked while rotating immediately after the moving direction of the annular edge, the extruded plasticizer is rearward in the forward direction of the conical surface. And is extended on the panel surface by the rotation of the conical surface. Therefore, the plasticizer does not become burrs and does not adhere as burrs to the panel surface.
[0006]
【Example】
Next, an embodiment will be described with reference to FIGS.
In this embodiment, the pin 11 has a diameter of 5 mm, and the tool body 12 has an outer diameter d1 of 21 mm. The outer peripheral portion of the shoulder surface of the tool main body has a conical surface (hereinafter referred to as a “running surface”) 13 that is convex downward with an inclination angle Θ equal to the advance angle (inclination angle of the joining tool). The advance angle in this embodiment is 3 degrees as in the prior art. The diameter d2 of the annular edge 14 on the inner periphery of the leveling surface 13 is 13 mm. The annular edge 14 is chamfered and the corners are dropped. Therefore, the radial width of the leveling surface 13 is 4 mm.
[0007]
When the joining tool T inclined at the advance angle Θ is advanced, the rear part in the advancing direction of the leveling surface 13 becomes parallel to the joint surface of the panel P, so that the plasticizer on the joint surface heated by frictional heat Is pushed outward by the rotational movement of the annular edge 14 of the tool shoulder surface which rotates at high speed, but the rear part in the traveling direction of the leveling surface 13 is in sliding contact with the joint surface in a parallel state. The plasticized material extruded outwardly from 14 is captured by the smoothing surface 13 and smoothed by the rotational movement.
[0008]
The radial width of the leveling surface 13 is appropriately in the range of 2 mm to 6 mm regardless of the diameter of the pin 11, and if it is less than 2 mm, the leveling function is insufficient, and a slight variability is formed on the outer side. May occur. The advance angle Θ of the welding tool is optimally about 3 degrees regardless of the diameter and length of the pin 11. However, even if the advance angle is larger than 3 degrees or smaller than 3 degrees, The optimum value of the radial width of the ridge surface 13 does not change.
[0009]
In addition, the inclination angle of the leveling surface 13 is equal to the advance angle. Therefore, the rearward direction portion of the leveling surface 13 is in sliding contact with the joint surface in a parallel state. The angle Θ need not be equal to the angle Θ, and may be smaller than the advance angle by, for example, about 0.3 degrees without any particular trouble in the leveling function.
[0010]
【effect】
As described above, the outer peripheral part of the shoulder surface of the welding tool is formed as a conical surface convex downward with an inclination angle equal to the advance angle. Since the material (aluminum material on the joint surface plasticized by frictional heat) is captured at the rear part in the direction of travel of the conical surface and is smoothed by its rotational movement, the plasticized material is pushed outward to the side. Therefore, it does not become burrs and adhere to the panel surface, and therefore the panel surface becomes extremely smooth.
Therefore, it is not necessary to finish the joint surface, and the joint can be painted as it is.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a joining tool of an embodiment.
FIG. 2 is a side view of a friction stir welding state with the welding tool of the embodiment.
FIG. 3 is a perspective view of a friction stir welding state with a conventional welding tool.
4 is a YY cross-sectional view of FIG.
[Explanation of symbols]
P: Panel W: Joining tool 11: Joining tool pin 12: Joining tool tool body 13: Leveling surface 14: Ring edge of leveling surface 13

Claims (2)

In the welding tool for friction stir welding, which moves forward in the inclined state,
A welding tool for friction stir welding in which the outer peripheral portion of the lower shoulder surface of the welding tool is a conical surface convex downward with an inclination angle equal to the forward inclination angle. The welding tool for friction stir welding according to claim 1, wherein the radial width of the conical surface is 2 mm to 6 mm.

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