JP2000246465A - Tools for friction stir welding - Google Patents

Abstract

(57) [Summary] [PROBLEMS] As a friction stir welding tool, it is possible to join a plurality of types of materials having different thicknesses at the portions to be welded, and it is stable and good even for thick materials. Provide a product that can ensure high bonding quality. SOLUTION: A probe 3 is concentrically protruded from a tip of a shaft-like base 2 attached to a rotation drive unit, and is inserted into a material to be joined while rotating the probe 3 to relatively move, thereby allowing the material to be joined to move. Is a friction stir welding tool 1A for performing the welding of the above, wherein the probe 3 is composed of a plurality of shaft portions 3a and 3b having a small diameter at the distal end side and having a stepwise different diameter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a friction stir welding tool used as a processing head when joining workpieces by a friction stir welding method.

[0002]

2. Description of the Related Art In recent years, friction stir welding (Friction) has been used as a new joining method instead of welding or brazing of metal materials.
n Stir Welding) method has appeared. This joining method is used, for example, when a probe (rod) made of a material harder than the workpiece is brought into sliding contact with the workpiece while rotating at a high speed, as disclosed in Japanese Patent Publication No. 7-505090. Because the workpiece material plastically fluidizes due to the frictional heat and pressure generated at the sliding contact portion, the probe can be embedded in the workpiece and can be moved through the workpiece in this embedded state. It is a thing that uses that it becomes.

For example, when the probe is relatively moved in the embedded state along the butt joint line between the metal plates, the materials of the two metal plates that have flowed plastically at the front side of the advancing probe are stirred and kneaded. The metal plate gradually moves to the rear side, and loses frictional heat at the rear side to rapidly cool and solidify. Therefore, the two metal plates are joined in a state where the respective materials are stirred and kneaded, and are completely integrated. In this case, the temperature at which the material plastically flows is much lower than the melting point, joining is in the category of solid-phase joining, the amount of heat input to the metal material during the joining process is extremely small compared to welding and brazing, and solidification shrinkage Therefore, there is an advantage that deformation and cracking due to thermal strain in the vicinity of the joint are not easily generated.

Conventionally, a friction stir welding tool (11) as shown in FIG. 5 has been generally used as a processing head in such friction stir welding. This tool (11)
Is a shaft-like base (1
At the tip of 2), a screw-shape probe (13) is protruded concentrically, and a shoulder (14) that forms a step between the shaft-shaped base (12) and the root of the probe (13) is located on the center side. It has a slightly concave shape. In the friction stir welding, as shown in FIG. 6, a probe (12) having a length substantially equal to the thickness (t) of the material (W) to be welded is rotated at a high speed. The tool (10) or the workpiece (W) is moved while the axis is slightly inclined backward with respect to the joining direction, and the shoulder (14) ) Presses the plastically-flowed material from above to level the joining surface.

[0005]

Therefore, in the conventional friction stir welding, it is necessary to replace the tool (11) every time the thickness (t) of the portion to be welded (C) changes. The exchange requires time and effort, and the machining efficiency is poor. In addition, various types of tools (11) having different lengths of the probe (12) must be prepared, so that there is a problem that the equipment cost increases accordingly. In addition, when the object to be joined is a thick material, especially when the thickness (t) of the part to be joined (C) is 7 mm or more, a defect is easily generated in the joined part, so that a good joined product can be stably obtained. It was difficult to obtain.

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention is capable of joining a plurality of types of materials having different thicknesses at the portions to be joined as a friction stir welding tool, and joining the thick materials. It is an object of the present invention to provide a product that can secure stable and good bonding quality.

[0007]

In order to achieve the above object, a friction stir welding tool according to the present invention is characterized in that a probe concentrically projecting from a tip of a shaft-like base attached to a rotary drive unit has a tip. It is characterized in that it is constituted by a plurality of shaft portions having different diameters stepwise with a small diameter on the side.

That is, in this friction stir welding tool, since the step portion between the shaft portions having different diameters in the probe functions as a shoulder portion, for example, the probe has two steps of the base side shaft portion and the tip side shaft portion. If it is a configuration, it can be used for two types of joining, the case where the thickness of the joined portion corresponds to the entire length of the probe and the case where the thickness corresponds to the length of the shaft portion on the distal end side,
Similarly, three types of the three-stage configuration and four types of the four-stage configuration can be commonly used for joining of the types corresponding to the number of stages.

On the other hand, it has been confirmed that the above-mentioned defects in joining thick materials by a conventional friction stir welding tool are likely to occur at an intermediate position in the thickness direction of the joint. This is because in the process of friction stir welding, pressing force is applied by the shoulder part on the upper side of the part to be welded, and stirring force by the tip surface of the probe is added on the lower side, while the probe peripheral surface at the middle position It is presumed that since the stirring force is weak due to friction alone, the materials to be joined are not sufficiently mixed with each other and the joining is likely to be insufficient. However, in the friction stir welding tool according to the present invention, when friction stir welding is performed in such a manner that a plurality of shaft portions of the probe (the entire length of the probe in a two-stage configuration) are embedded, a shoulder portion at a step between the shaft portions is formed. Since the portion to be welded is located at the middle position in the thickness direction, the pressing force and the friction by the shoulder portion are applied, and the stirring force at the middle position is increased, so that the generation of defects can be suppressed even when a thick material is to be bonded.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below with reference to the drawings. 1 and 2 show a first embodiment, and FIGS. 3 and 4 show a second embodiment.

As shown in FIG. 1, in the friction stir welding tool (1A) of the first embodiment, a probe (3) is concentrically mounted on the tip of a shaft-like base (2) attached to a rotary drive (not shown). The probe (3) has a two-stage configuration of a large-diameter base-side shaft (3a) and a small-diameter distal-side shaft (3b), and has both shafts (3a) and (3b). A thread (5) is engraved on the outer periphery of. The step between the shaft-like base (2) and the root of the probe (3) forms a first shoulder (4a), and the step between the base-side shaft (3a) and the tip-side shaft (3b). Constitutes a second shoulder portion (4b), and both shoulder portions (4a) and (4b) are low and concave toward the center.

In this friction stir welding tool (1A), if the total length of the probe (3) is L1 and the length of the distal end shaft portion (3b) is L2, the thickness of the portion to be welded is approximately L1 and L2. It can be commonly used for joining two kinds of materials to be joined. That is, FIG.
The thick workpiece (W1) shown in (a) has a thickness t1 of L1.
Therefore, when friction stir welding is performed by abutting the pair, the tool (1A) is rotated at a high speed with the axis (O) slightly inclined backward with respect to the welding direction (arrow a), and the first shoulder portion is rotated. The probe (3) is inserted up to the base (C) where the probe (3) is abutted so that the (4a) comes into contact with the surface of the workpiece (W1), and the tool (1A) is relatively moved in this embedded state. Just do it. In addition, since the thickness t2 of the thin workpiece (W2) shown in FIG. 2B is substantially equal to L2, the second shoulder portion is rotated while the tool (1A) is rotated at a high speed in the same manner. Probe (3) so that (4b) is in contact with the surface of the workpiece (W2)
May be embedded in the to-be-joined part (C), and the tool (1A) may be relatively moved in this embedded state.

Thus, the former thick material to be joined (W
In the friction stir welding of 1), since the second shoulder portion (4b) of the probe (3) comes to an intermediate position in the thickness direction of the portion to be joined (C), the pressing force and friction by the second shoulder portion (4b) are increased. As a result, a strong stirring force acts on the intermediate position. Therefore, when a thick material is to be welded, as described above, the conventional friction stir welding tends to cause a defect due to insufficient stirring force at the middle position in the thickness direction, but the friction stir welding tool (1A) As shown in FIG. 2 (a), the bonding is performed by embedding the entire length of the probe (3) so that the thickness of the portion to be bonded, which has been difficult in the past, is reduced to 7%.
Needless to say, if the thickness is more than 10 mm, a good bonded product can be stably obtained even when the thickness exceeds 10 mm. In the friction stir welding tool (1B) according to the second embodiment shown in FIG. 3, the probe (3) protruding from the tip of the shaft-like base (2) has a large-diameter base-side shaft (3a) and an intermediate portion. The diameter of the intermediate shaft (3b) and the diameter of the distal shaft (3c) are small.
The shafts (3a) to (3c) have a stepped structure, and a thread (5) is also engraved on the outer periphery of each of the shafts (3a) to (3c). The step between the shaft-shaped base (2) and the root of the probe (3) is the first shoulder (4a), the base-side shaft (3a) and the intermediate shaft (3b).
Is different from the second shoulder part (4b) and the intermediate shaft part (3
b) and the step portion between the tip side shaft portion (3c) becomes the third shoulder portion (4c), and these shoulder portions (4a) to (4c)
In each of the cases c), the shape is low and concave toward the center.

In the friction stir welding tool (1B), the total length of the probe (3) is L1, the total length of the intermediate shaft (3b) and the distal shaft (3c) is L2, and the distal shaft (3c). )
Let L3 be the length of L3, it can be used for joining three types of materials to be joined whose thickness of the portion to be joined is approximately equal to any of L1 to L3.
As shown by the solid line in FIG. 4, if the material to be joined (W1) having a thickness t1 substantially equal to L1 is to be joined, the first shoulder portion (4a) is attached to the surface of the material to be joined (W1). The entire length of the probe (3) may be embedded in the portion to be welded (C) so as to be in contact therewith, and friction stir welding may be performed as in the first embodiment. Then, as shown by the imaginary line in FIG. 4, if the material to be welded (W2) whose wall thickness t2 is substantially equal to L2 is to be bonded, it reaches the position of the second shoulder portion (4b) and the wall thickness t3 becomes L3. If the material to be welded (W3) is substantially the same, the probe (3) is embedded in the material to be welded (C) up to the position of the third shoulder (4c), and friction stir welding is performed in the same manner as in the first embodiment. Just do it.

The friction stir welding tool (1) of the second embodiment
Also in B), the second and third shoulder portions (4b) and (4c) and the intermediate shaft portion (3b) are used when the full length of the probe (3) is buried in the portion to be bonded (C) and bonding is performed. ) And the tip side shaft portion (3c) are embedded and joined, the third shoulder portions (4b) and (4c) apply a strong stirring force at the middle portion in the thickness direction of the joined portion (C). Therefore, it can be preferably applied to the joining of a thick material as in the tool (1A) of the first embodiment.

In the first and second embodiments, the probe (3) has a two-stage or three-stage configuration. However, the friction stir welding tool of the present invention has a multi-stage configuration of four or more stages. It is also possible. Also, the total length of the probe (3),
The length ratio and diameter of each shaft portion, the width of each shoulder portion, and the like can be variously set according to the size and material of the material to be joined. It is needless to say that the friction stir welding tool according to the present invention can be applied not only to the butted portion of the materials to be joined as illustrated but also to the joining of the overlapped portion and the fitting portion.

[0017]

According to the present invention, friction stir is performed in which the probe protruding from the tip of the shaft-like substrate is embedded in the material to be joined while rotating and relatively moved to join the material to be joined. As a joining tool, a tool that can be used for joining a plurality of types of materials having different thicknesses at the portions to be joined and that can secure a stable and good joining quality even when a thick material is to be joined. Provided.

[Brief description of the drawings]

FIG. 1 is a half sectional side view of a main part of a friction stir welding tool according to a first embodiment of the present invention.

FIGS. 2A and 2B show a joining state by the friction stir welding tool of the first embodiment. FIG. 2A is a longitudinal side view when the joining object is a thick material, and FIG. It is a vertical side view when it is.

FIG. 3 is a half sectional side view of a main part of a friction stir welding tool according to a second embodiment of the present invention.

FIG. 4 is a longitudinal sectional side view showing a joining state by the friction stir welding tool of the second embodiment.

FIG. 5 is a half sectional side view of a main part of a conventional friction stir welding tool.

FIG. 6 is a longitudinal sectional side view showing a joining state by a conventional friction stir welding tool.

[Explanation of symbols]

 1A, 1B ··········································································· Probe 3a to 3b ······· Shaft 4a to 4c. ····· Shoulder portion W1 to W3 ·····································

Claims (1)

[Claims] A probe is concentrically protruded from a tip of a shaft-like base attached to a rotary drive unit, and is inserted into a material to be joined while rotating and relatively moved, thereby rotating the probe. A friction stir welding tool for performing welding, wherein the probe is formed of a plurality of shaft portions having a small diameter at the tip end side and having different diameters in a stepwise manner.