JP2015174138A - Friction-agitation joining tool, and friction-agitation joining method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a friction-agitation joining tool capable of increasing an agitation force in a tool rotation axis direction and reducing a friction agitation joining cost, and reducing a friction-agitation joining cost, without working a joined member to be friction-agitation joined.SOLUTION: A friction-agitation joining tool is constructed to have: a large-diameter shoulder 2; a small-diameter probe 3 connected to the shoulder 2; and a tool holding part 4 to be gripped by a rotation device corresponding an upper part of the shoulder 2 and given a rotating force. The probe 3 has an inverse tapered part having the diameter reduced toward the shoulder 2.

Description

  The present invention relates to a friction stir welding tool and a friction stir welding method, and is particularly suitable for joining lap joints.

  Friction stir welding is a method in which a solid tool is joined by inserting a rotating tool called a tool into a joint and moving the joint along a joining line while rotating the tool. Since the friction stir welding can be performed at a melting temperature or lower, there are many advantages such as a decrease in strength of the joint due to transformation of the metal structure and small deformation. However, inadequate agitation may cause defects and decrease in bonding strength. In a general friction stir welding tool, the stirring force in the rotation direction of the tool is large, but the stirring force in the rotation axis direction is small. In particular, in friction stir welding for joining lap joints, there is a problem of strength reduction due to insufficient stirring of the joint surfaces.

  As a countermeasure against this problem, a method is disclosed in which the lap joint portion is inclined, the friction stir welding tool is inserted in an inclined state with respect to the overlap surface, and the friction stir welding is performed (for example, Patent Document 1).

JP 2001-79672 A (paragraphs [0011] to [0014], FIG. 1)

  However, in the disclosed invention of Patent Document 1, since processing to a member to be joined is necessary before friction stir welding, there is a problem that processing cost at the time of joining becomes high.

  The present invention has been made to solve the above-described problems. A friction stir welding tool and a friction stir welding method capable of increasing the stirring force in the tool rotation axis direction without processing a member to be joined. The purpose is to provide.

  The friction stir welding tool according to the present invention is composed of a large-diameter shoulder and a small-diameter probe connected to the shoulder, and the probe has an inversely tapered portion that decreases in diameter toward the shoulder.

  In the friction stir welding method according to the present invention, the probe connected to the shoulder uses a friction stir welding tool having a reverse taper-shaped portion whose diameter decreases toward the shoulder, and the friction stir welding tool is rotated to rotate the first tool. An insertion step of inserting between the member to be joined and the second member to be joined, a friction stir welding step of performing friction stir welding by moving along the joining line while rotating the tool for friction stir welding, and for friction stir welding And a drawing step in which the tool is rotated and pulled out from the first and second members to be joined.

  Since the friction stir welding tool according to the present invention is configured as described above, the stirring force in the rotational axis direction increases, internal defects due to insufficient stirring can be eliminated, and the bonding strength can be increased. it can. Moreover, since it is not necessary to process into the joining surface of a to-be-joined member, the cost of friction stir welding can be reduced.

  Since the friction stir welding method according to the present invention includes the steps as described above, the stirring force in the direction of the rotation axis increases, internal defects due to insufficient stirring can be eliminated, and the bonding strength can be increased. Moreover, since it is not necessary to process into the joining surface of a to-be-joined member, the cost of friction stir welding can be reduced.

It is a block diagram which concerns on the tool for friction stir welding of Embodiment 1 of this invention. It is explanatory drawing for a comparison which concerns on the tool for friction stir welding of Embodiment 1 of this invention. It is explanatory drawing for a comparison which concerns on the tool for friction stir welding of Embodiment 1 of this invention. It is explanatory drawing for a comparison which concerns on the tool for friction stir welding of Embodiment 1 of this invention. It is stirring explanatory drawing which concerns on the tool for friction stir welding of Embodiment 1 of this invention. It is a joining shape schematic diagram which concerns on the tool for friction stir welding of Embodiment 1 of this invention. It is a process example figure which concerns on the tool for friction stir welding of Embodiment 1 of this invention. It is a joining shape schematic diagram of the example of processing concerning the tool for friction stir welding of Embodiment 1 of this invention. It is a block diagram which concerns on the tool for friction stir welding of Embodiment 2 of this invention. It is a block diagram which concerns on the tool for friction stir welding of Embodiment 3 of this invention. It is a block diagram which concerns on the tool for friction stir welding of Embodiment 4 of this invention. It is a block diagram which concerns on the tool for friction stir welding of Embodiment 5 of this invention. It is a flowchart which concerns on the friction stir welding method of Embodiment 6 of this invention. It is explanatory drawing which concerns on the friction stir welding method of Embodiment 7 of this invention. It is explanatory drawing for a comparison which concerns on the friction stir welding method of Embodiment 7 of this invention.

Embodiment 1 FIG.
The first embodiment relates to a friction stir welding tool that includes a large-diameter shoulder and a small-diameter probe connected to the shoulder, and the probe has a reverse tapered shape portion that decreases in diameter toward the shoulder.

  Hereinafter, with respect to the configuration and function of the friction stir welding tool 1 according to the first embodiment of the present invention, FIG. 1 which is a configuration diagram of the friction stir welding tool, FIG. 2 to FIG. 5 which is a diagram, FIG. 6 which is a schematic diagram of a joint shape, FIG. 7 which is a diagram of a processing example, and FIG. 8 which is a schematic diagram of a joint shape of a processing example.

FIG. 1 shows a basic configuration of a friction stir welding tool 1 according to Embodiment 1 of the present invention.
In FIG. 1, the friction stir welding tool 1 includes a large-diameter shoulder 2, a small-diameter probe 3 connected to the shoulder 2, and a tool holding portion 4 corresponding to the upper portion of the shoulder 2. The probe 3 has an inversely tapered portion that decreases in diameter toward the shoulder 2. The tool holding unit 4 is held by a rotating device (not shown), and a rotational force is applied to the friction stir welding tool 1.
The shoulder 2 is generally a portion to which the probe 3 below the tool holding portion 4 is connected, and may be referred to as a shoulder surface.
In addition, when it is clear that the friction stir welding tool is for friction stir welding, the tool is appropriately described as a welding tool or a tool.

First, the outline and features of the friction stir welding and the friction stir welding tool will be described.
Friction stir welding is a joining method in which a rod-shaped tool called a friction stir welding tool is brought into contact with a member to be joined while rotating at high speed, and the friction heat of the member to be joined and the friction stir welding tool is used for joining. is there. Friction stir welding is a technique for joining in a solid state, and the highest joining temperature is below the melting point. For this reason, compared with fusion welding, there are many advantages such as a decrease in strength at the joint and a small joint deformation.

  A friction stir welding tool used for friction stir welding is generally cylindrical, and includes a shoulder having a large diameter and a probe having a small diameter at the tip thereof. During bonding, the probe is inserted into the member to be bonded and moved along the bonding line. The members to be joined that have been softened by frictional heat are agitated with a friction stir welding tool, and are joined by causing plastic flow.

  The friction stir welding tool requires a material having a higher melting point and higher high-temperature strength than the members to be joined. When joining an aluminum alloy, it is common to use SK (carbon tool steel) or SKD (alloy tool steel) such as SKD61. In recent years, friction stir welding is also used for mild steel and stainless steel. In this case, a cobalt alloy or a cemented carbide is used as a friction stir welding tool.

  Friction stir welding is a method in which the members to be joined are agitated and joined with a friction stir welding tool, so if the stirring force of the friction stir welding tool is small, tunnel-like internal defects or unjoined parts occur. , The bonding strength decreases. The stirring force varies depending on the friction stir welding conditions such as the rotation speed, the joining speed, the insertion depth of the friction stir welding tool, and the shape of the friction stir welding tool.

  Since friction stir welding uses friction heat, the friction heat of friction stir welding depends on the diameter of the probe, and the larger the diameter, the greater the amount of heat generated. In addition, when a temperature gradient occurs in the fluid, a flow due to a temperature difference occurs. Therefore, by providing a difference in the diameter of the probe, a temperature difference is generated in the joining region in the tool rotation axis direction, and the members to be joined can be stirred in the rotation axis direction. That is, by providing the probe of the friction stir welding tool with a taper shape, the stirring force in the rotation axis direction increases.

Next, the function of the friction stir welding tool 1 of the first embodiment will be described while comparing with a conventional friction stir welding tool.
First, the configuration and function of a conventional friction stir welding tool will be described.
FIG. 2 is a configuration diagram of a conventional friction stir welding tool. In FIG. 2A, the friction stir welding tool 101 includes a large-diameter shoulder 102, a small-diameter probe 103 connected to the shoulder 102, and a tool holding unit 104 on the shoulder 102.
In FIG. 2B, the friction stir welding tool 121 includes a large-diameter shoulder 122, a small-diameter probe 123 connected to the shoulder 122, and a tool holding portion 124 on the shoulder 122.
The difference between the friction stir welding tool 101 in FIG. 2A and the friction stir welding tool 121 in FIG. 2B is the shape of the probe. The probe 103 of the friction stir welding tool 101 has a tapered shape, but the probe 123 of the friction stir welding tool 121 has a straight shape.

FIG. 3 is an explanatory diagram of stirring when performing friction stir welding using the conventional friction stir welding tool 101. A state in which the probe 103 of the friction stir welding tool 101 is rotationally inserted into the first member 5 to be joined is shown.
The probe 103 is rotated to generate frictional heat, and the first bonded member 5 around the probe 103 is agitated to form a bonding region 107. The temperature of the portion where the diameter of the probe 103 is large (the end surface portion of the shoulder 102) is higher than the temperature where the diameter of the probe 103 is small (the tip portion of the probe 103).

  FIG. 4 shows a joining shape after the friction stir welding tool 101 is pulled out from the state of FIG.

Next, the state of the friction stirrer when the conventional friction stir welding tools 101 and 121 are used will be specifically described.
In the case of the tapered probe 103 whose tip is tapered as shown in FIG. 2A, the amount of heat generated on the shoulder 102 side is larger than that on the tip of the probe 103. For this reason, since the upper part of the joining area | region 107 becomes high temperature and the lower part becomes low temperature, stirring as shown in FIG. 3 arises. That is, since the upper part of the joining region 107 becomes high temperature and the specific gravity is lightened, the upward stirring 108 flows. Since the lower part of the joining region 107 has a low temperature and a high specific gravity, a downward stirring 109 flow occurs.
This is a stirring direction that separates the members to be joined vertically, and an internal defect 110 occurs in the joining cross section as shown in FIG.

  In the case of a straight probe as shown in FIG. 2B, the amount of heat generated by the probe 123 is substantially constant, and the stirring force in the rotation axis direction due to the temperature difference does not contribute. Therefore, the stirring in the direction of the rotation axis of the friction stir welding tool is insufficient, and there is a high possibility that the welding cross section has an internal defect as in FIG. Even in the case where no internal defect occurs, in the case of the first bonded member 5 having a strong oxide film such as an aluminum alloy or stainless steel, the oxide film may remain on the bonding surface and the bonding strength may be reduced.

Actually, A6063 (aluminum alloy material) is a friction stir welding tool shown in FIGS. 2A and 2B (the probe has a straight shape, and the probe has a taper shape tapered toward the tip). ), Internal defects were confirmed under all conditions (rotation speed: 500-2500 rpm, welding speed: 100-2000 mm / min).
Moreover, even when there is no internal defect, there is a high possibility that the bonding becomes insufficient and the bonding strength is lowered.
Therefore, in the conventional friction stir welding tools 101 and 121 shown in FIGS. 2A and 2B, there is a concern that the strength of the friction stir welding of the lap joint is particularly insufficient.

  In order to compensate for this drawback of the conventional friction stir welding tool, the probe may be provided with irregularities such as a reverse screw in order to improve the stirring force in the rotation axis direction of the friction stir welding tool. However, although the stirring force is improved by providing irregularities on the probe, it is difficult to process the probe into a screw shape, and the friction stir welding tool becomes expensive. In the friction stir welding, since the friction stir welding tool is a consumable item, the increase in the tool cost greatly affects the processing cost.

The friction stir welding tool 1 according to the first embodiment has been developed to increase the stirring force in the tool rotation axis direction with a simple shape.
Functions and features of the friction stir welding tool 1 will be described with reference to FIGS.
As described with reference to FIG. 1, the friction stir welding tool 1 includes a shoulder 2 and a probe 3, and the probe 3 has an inversely tapered shape with a diameter decreasing toward the shoulder 2.

FIG. 5 is an explanatory diagram of stirring when the friction stir welding is performed using the friction stir welding tool 1 of the first embodiment. The state where the probe 3 of the friction stir welding tool 1 is rotationally inserted into the first member 5 to be joined is shown.
The probe 3 rotates to generate frictional heat, and the first bonded member 5 around the probe 3 is agitated to form a bonding region 7. The temperature of the portion with the large diameter of the probe 3 (tip portion of the probe 3) is higher than the temperature of the portion with the small diameter of the probe 3 (connecting portion with the shoulder 2).

  FIG. 6 shows a joining shape after the friction stir welding tool 101 is pulled out from the state of FIG.

Since the probe 3 of the friction stir welding tool 1 according to the first embodiment has an inversely tapered shape with a diameter becoming narrower toward the shoulder 2, the amount of heat generated on the shoulder 2 side is smaller than that on the tip of the probe 3. For this reason, the upper part of the joining area | region 7 becomes low temperature, and a lower part becomes high temperature, and stirring as shown in FIG. 5 arises.
That is, since the lower part of the joining region 7 becomes high temperature and the specific gravity becomes light, an upward stirring 8 flow occurs. Since the upper part of the joining region 7 becomes low temperature and the specific gravity becomes heavy, a downward stirring 9 flow occurs. This is a stirring direction that mixes the members to be joined from above and below.

  Since the friction stir welding tool 1 having the probe 3 can be stirred so that the joints are mixed in the direction of the rotation axis, the occurrence of internal defects can be suppressed, and a sound joint as shown in FIG. 6 can be obtained. Furthermore, by stirring so that the upper part of the 1st to-be-joined member 5 is pushed down, the effect which suppresses generation | occurrence | production of a burr | flash is also acquired.

As described above, by providing the probe 3 with a reverse taper shape, the stirring force in the direction of the rotation axis is improved, the occurrence of internal defects and burrs due to insufficient stirring can be suppressed, and the decrease in bonding strength can be suppressed.
The friction stir welding tool 1 of the first embodiment is particularly effective for friction stir welding of lap joints.

Next, a specific example in which the friction stir welding tool 1 is applied to the joining of a lap joint will be described with reference to FIGS.
FIG. 7 shows a configuration in which friction stir welding is performed using the friction stir welding tool 1 on the overlap joint composed of the first member 5 and the second member 6.
FIG. 8 shows a state in which the probe 3 of the friction stir welding tool 1 is inserted into the overlap joint composed of the first member 5 and the second member 6, friction stir welding is performed, and the probe 3 is pulled out. . A junction region 7 free from internal defects is formed.

In the friction stir welding tool 1 according to the first embodiment, the probe 3 has been described as having an inversely tapered shape whose diameter decreases toward the shoulder 2, but this inversely tapered shape is the same for a part of the probe 3. There is an effect.
Further, by providing the probe 3 with unevenness such as a reverse screw, the stirring force can be further increased.

  As described above, the friction stir welding tool 1 according to the first embodiment is configured by a large-diameter shoulder and a small-diameter probe connected to the shoulder, and the probe has an inversely tapered portion whose diameter decreases toward the shoulder. It is what has. Therefore, since the stirring force in the rotation axis direction increases, internal defects due to insufficient stirring can be eliminated, and the bonding strength can be increased. Moreover, since it is not necessary to process into the joining surface of a to-be-joined member, the cost of friction stir welding can be reduced.

  Furthermore, the working efficiency of the friction stir welding, that is, the productivity is improved, and the yield of products can be improved.

Embodiment 2. FIG.
Although the friction stir welding tool of the second embodiment has an inversely tapered shape, it includes a probe in which the diameter of the probe tip is smaller than the diameter of the shoulder connecting portion.
Hereinafter, the configuration and function of the friction stir welding tool of the second embodiment will be described based on FIG. 9 which is a configuration diagram, focusing on the differences from the friction stir welding tool of the first embodiment.
In FIG. 9, the same or corresponding parts as in FIG.

FIG. 9 shows the configuration of the friction stir welding tool 21 according to the second embodiment of the present invention.
The friction stir welding tool 21 includes a large-diameter shoulder 2, a small-diameter probe 23 connected to the shoulder 2, and a tool holding unit 4 corresponding to the upper portion of the shoulder 2.
The shape of the probe is different from the friction stir welding tool 1 of the first embodiment. The probe 23 has a tapered shape that tapers from the connecting portion with the shoulder 2 toward the tip, and has a reverse tapered shape from the middle. If the diameter of the connecting portion with the shoulder 2 is d1, and the diameter of the tip of the probe 3 is d2, there is a relationship of d1> d2.

  In friction stir welding, when the rotated friction stir welding tool is inserted into the first welded member 5, the first welded member 5 is heated and softened by frictional heat with the friction stir welding tool. Since the temperature of the 1st to-be-joined member 5 has not fully raised at the time of insertion, it has high rigidity. Therefore, particularly when a tool is inserted, a large load is applied, and the friction stir welding tool may be damaged.

The friction stir welding tool 21 according to the second embodiment can reduce the tool load applied at the time of insertion, and can suppress damage to the friction stir welding tool at the time of tool insertion.
As described with reference to FIG. 9, the friction stir welding tool 21 is characterized in that the diameter of the tip of the probe 3 is smaller than the diameter of the connecting portion with the shoulder 2.

  When the tool was inserted, a large tool load was applied in the tool insertion direction, and the load in the tool insertion direction was maximized when the probe was inserted into the first member 5 to be joined. Further, the weight in the tool insertion direction depends on the diameter of the probe tip, and the tool weight in the insertion direction increases as the diameter of the tip of the probe increases. That is, in order to suppress damage to the friction stir welding tool due to load in the tool insertion direction, it is necessary to reduce the diameter of the probe tip.

  Table 1 shows the results of the friction stir welding performed by changing the diameter of the probe 23 (the connecting portion with the shoulder and the tip) with the friction stir welding tool 21 of the second embodiment. In addition, it is the result of using A6063 for the friction stir welding target material under the joining conditions of a diameter of the shoulder 2 of 12 mm, a length of the probe 23 of 3 mm, a rotational speed of 3000 rpm, a joining speed of 500 mm / min, and an insertion speed of 10 mm / min.

  As shown in Table 1, when the diameter d2 of the tip of the probe 23 is larger than the diameter d1 of the connecting portion with the shoulder 2, and when the diameter d1 of the connecting portion between the tip diameter d2 and the shoulder 2 is the same, the probe 23 could be damaged.

  On the other hand, when the diameter d2 at the tip of the probe 23 was smaller than the diameter d1 of the connecting portion with the shoulder 2, the probe 23 was not damaged. The damage of the probe 23 is caused by the temperature rise of the probe 23 due to frictional heat and the tool load in the insertion direction. As the temperature rises, the strength of the probe 23 decreases, and the probe 23 is damaged by applying a tool load beyond that strength.

In the case of the friction stir welding tool 21 according to the second embodiment, since the diameter of the tip of the probe 23 is small, the temperature rise of the probe 23 and the tool load in the insertion direction can be suppressed. Furthermore, by increasing the diameter of the connecting portion with the shoulder 2 from the tip of the probe 23, the heat capacity of the probe 23 is increased, and damage to the probe 23 can be suppressed.
Therefore, by using the friction stir welding tool 21, the friction stir welding can be performed without damaging the probe and without reducing the bonding strength due to insufficient stirring.

  As described above, the friction stir welding tool of the second embodiment has an inverted taper shape, but includes a probe in which the diameter of the probe tip is smaller than the diameter of the shoulder connecting portion. Therefore, in addition to the effects of the first embodiment, tool weight can be suppressed, and damage to the probe can be suppressed.

Embodiment 3 FIG.
The friction stir welding tool according to the third embodiment has an inverted taper shape, but includes a probe in which the probe tip is chamfered to reduce the diameter of the probe tip.
Hereinafter, the configuration and function of the friction stir welding tool of the third embodiment will be described based on FIG. 10 which is a configuration diagram, focusing on the differences from the friction stir welding tool of the first embodiment.
In FIG. 10, the same or corresponding parts as those in FIG.

FIG. 10 shows the configuration of the friction stir welding tool 31 according to the third embodiment of the present invention.
The friction stir welding tool 31 includes a large-diameter shoulder 2, a small-diameter probe 33 connected to the shoulder 2, and a tool holding unit 4 corresponding to the upper portion of the shoulder 2.
The shape of the probe is different from the friction stir welding tool 1 of the first embodiment. The probe 33 has a reverse taper shape from the shoulder 2 toward the tip, but the tip is chamfered to reduce the diameter of the tip of the probe 33.

  As described above, the tool load in the insertion direction applied during insertion depends on the diameter of the tip of the probe, and if the diameter is large, the probe may be damaged. In the friction stir welding tool 1 of the first embodiment, it was possible to suppress a decrease in bonding strength due to insufficient stirring force and the occurrence of internal defects. Further, the effect was improved by increasing the taper angle. However, if the diameter of the tip of the probe 3 was too large, the probe was damaged.

The friction stir welding tool 31 according to the third embodiment can increase the effect of suppressing the decrease in bonding strength due to insufficient stirring force and the occurrence of internal defects without damaging the probe.
The friction stir welding tool 31 of FIG. 10 has a reverse taper shape in which the probe 33 expands from the connecting portion with the shoulder 2 toward the tip of the probe 33, and the tip of the probe 33 is chamfered so that the tip of the probe 33 is It has a tapered shape. The chamfering may be either C chamfering or R chamfering.

  By chamfering the tip of the probe 33, the diameter of the tip of the probe 33 can be reduced, and the tool load in the insertion direction can be suppressed. At this time, it is desirable that the diameter of the tip of the probe 33 is smaller than the diameter of the connecting portion with the shoulder 2. Moreover, since the probe 33 can be agitated in the direction of pushing down the first member 5 by making the probe 33 have an inversely tapered shape, the occurrence of internal defects can be suppressed.

  As described above, the friction stir welding tool according to the third embodiment has an inverted taper shape, but includes a probe in which the probe tip is chamfered to reduce the diameter of the probe tip. Therefore, in addition to the effects of the first embodiment, tool weight can be suppressed, and damage to the probe can be suppressed.

Embodiment 4 FIG.
The tool for friction stir welding according to the fourth embodiment includes a probe having a reverse taper shape, in which the maximum diameter dmax of the probe tip is 1.1 to 2 times the minimum diameter dmin of the connecting portion with the shoulder. Is.
Hereinafter, the configuration and function of the friction stir welding tool of the fourth embodiment will be described based on FIG. 11 which is a configuration diagram, focusing on the differences from the friction stir welding tool of the first embodiment.
In FIG. 11, the same or corresponding parts as in FIG.

FIG. 11 shows a configuration of a friction stir welding tool 41 according to the fourth embodiment of the present invention.
The friction stir welding tool 41 includes a large-diameter shoulder 2, a small-diameter probe 43 connected to the shoulder 2, and a tool holding unit 4 corresponding to the upper portion of the shoulder 2.
The shape of the probe is different from the friction stir welding tool 1 of the first embodiment. The probe 43 has a reverse taper shape from the shoulder 2 toward the tip. If the diameter (minimum diameter) of the connecting portion with the shoulder 2 is dmin and the diameter (maximum diameter) of the tip of the probe 43 is dmax: There is a relationship of 1 dmin <dmax <2 dmin.

  The probe 3 of the friction stir welding tool 1 according to the first embodiment is provided with a reverse taper shape so that the diameter increases from the connecting portion with the shoulder 2 toward the tip, thereby rotating the friction stir welding tool 1 in the rotational axis direction. The stirring force increases. However, an excessive reverse taper shape increased the tool load and damaged the probe 3.

  Therefore, a friction stir welding tool 1 in which the maximum diameter and the minimum diameter of the probe 3 were changed was prepared, and the reverse taper shape of the probe 3 capable of satisfactory bonding was investigated. Table 2 shows the experimental results. This is a result of using A6063 as a friction stir welding target material under the joining conditions of a diameter of the shoulder 2 of 12 mm, a length of the probe 3 of 3 mm, a rotational speed of 3000 rpm, a joining speed of 500 mm / min, and an insertion speed of 10 mm / min.

  From the experimental results, when the maximum diameter dmax of the probe 3 was 1.1 times or less than the minimum diameter dmin, the stirring force was hardly increased, the stirring was insufficient, and defects were generated inside the joint. Further, when the maximum diameter dmax was twice or more than the minimum diameter dmin, the heat generation amount was high, and the probe 3 was damaged. By setting the maximum diameter dmax of the probe 3 to 1.1 to twice the minimum diameter dmin, good bonding is possible.

  In the description of the fourth embodiment, the application to the friction stir welding tool of the first embodiment has been mainly described. However, the present invention can be similarly applied to the friction stir welding tool of the second and third embodiments.

  As described above, the friction stir welding tool of the fourth embodiment has an inversely tapered shape, and the maximum diameter dmax of the probe tip is 1.1 to 2 with respect to the minimum diameter dmin of the connecting portion with the shoulder. A doubled probe is provided. Therefore, in addition to the effects of the first embodiment, tool weight can be suppressed, and damage to the probe can be suppressed.

Embodiment 5 FIG.
The friction stir welding tool of the fifth embodiment has a reverse taper shape and includes a probe in which the diameter d1 of the shoulder connecting portion is d1> L with respect to the length L of the probe.
Hereinafter, the configuration and function of the friction stir welding tool of the fifth embodiment will be described based on FIG. 12 which is a configuration diagram, focusing on the differences from the friction stir welding tool of the first embodiment.
In FIG. 12, the same or corresponding parts as those in FIG.

FIG. 12 shows the configuration of a friction stir welding tool 51 according to the fifth embodiment of the present invention.
The friction stir welding tool 51 includes a large-diameter shoulder 2, a small-diameter probe 53 connected to the shoulder 2, and a tool holding unit 4 corresponding to the upper portion of the shoulder 2.
The shape of the probe is different from the friction stir welding tool 1 of the first embodiment. The probe 53 has a reverse taper shape from the shoulder 2 toward the tip, but if the diameter (minimum diameter) of the connecting portion with the shoulder 2 is d1 and the length of the probe 43 is L, there is a relationship of d1> L. .

  The probe 3 of the friction stir welding tool 1 according to the first embodiment is provided with a reverse taper shape so that the diameter increases from the connecting portion with the shoulder 2 toward the tip, thereby rotating the friction stir welding tool 1 in the rotational axis direction. The stirring force increases. However, in friction stir welding, since a load of several kN is applied in the joining direction during joining, if the diameter of the probe 3 is too thin, the probe load applied during joining cannot be withstood and damaged due to insufficient rigidity of the probe 3. there is a possibility.

  The probe 3 during friction stir welding is subjected to bending stress like a cantilever beam. This bending stress depends on the cross-sectional area and length of the probe 3, and the tool load in the joining direction increases as the cross-sectional area of the probe 3 increases and the length increases. When the probe 3 cannot withstand the bending stress, the probe 3 is damaged. Note that the rigidity of the probe 3 depends on the minimum diameter of the probe 3.

  In the friction stir welding tool 1 of the first embodiment, since the probe 3 has a larger diameter at the tip than the connecting portion of the shoulder 2, a larger bending stress is applied to the probe 3 than in the conventional friction stir welding tool. When the length of the probe 3 is long, the probe 3 may be damaged.

  Accordingly, the friction stir welding tool 1 in which the length of the probe 3 and the minimum diameter are changed is prepared, and the experimental results are shown in Table 3. In addition, it is the result of using A6063 for the friction stir welding target material under the joining conditions of the diameter of the shoulder 2 of 12 mm, the rotational speed of 3000 rpm, the joining speed of 500 mm / min, and the insertion speed of 10 mm / min.

  From the experimental results, when the length of the probe 3 was shorter than the minimum diameter of the probe 3, the probe 3 was not damaged and good bonding was possible.

  In the description of the fifth embodiment, the application to the friction stir welding tool of the first embodiment has been mainly described, but the present invention can be similarly applied to the friction stir welding tool of the second to fourth embodiments.

  As described above, the friction stir welding tool of the fifth embodiment has a reverse tapered shape and includes a probe in which the diameter d1 of the shoulder connecting portion is d1> L with respect to the length L of the probe. is there. Therefore, in addition to the effects of the first embodiment, damage to the probe can be suppressed.

Embodiment 6 FIG.
The friction stir welding method according to the sixth embodiment includes an insertion process, a friction stir welding process, and a drawing process using the friction stir welding tool 1 according to the first embodiment.
Hereinafter, with respect to the friction stir welding method of the sixth embodiment, based on the flowchart of FIG. 13, FIG. 1 is a configuration diagram of the friction stir welding tool 1 of the first embodiment, FIG. This will be described with reference to FIGS.

When the process is started, first, in step 1 (S01), the friction stir welding tool 1 is rotated at a predetermined rotational speed to form a predetermined joint on the lap joint composed of the first member 5 and the second member 6. Is inserted at an insertion speed of (insertion step).
Next, in step 2 (S02), the friction stir welding is performed by rotating the friction stir welding tool 1 at a predetermined joining speed along the welding line (friction stir welding step).
Next, in step 3 (S03), the friction stir welding tool 1 is rotated and pulled out from the overlap joint composed of the first member 5 and the second member 6 (pulling step).
In the insertion step (S01), when the probe 3 of the friction stir welding tool 1 is inserted, it is assumed that the shoulder 2 is pressed against the upper surface of the first member 5 to be joined (see FIG. 5). .

  Although it is not necessary to change the rotation speed of the friction stir welding tool 1 in each work process, the tool load in the tool rotation axis direction can be reduced by increasing the rotation speed in the insertion process. For this reason, in order to suppress damage to the friction stir welding tool 1, it is desirable to increase the rotational speed of the insertion step.

  In the description of the friction stir welding method according to the sixth embodiment, the friction stir welding tool 1 according to the first embodiment is used, but the friction stir welding tool 21 described in the second to fifth embodiments is used for joining. Tool 51 can be used.

  As described above, the friction stir welding method according to the sixth embodiment includes the insertion step, the friction stir welding step, and the drawing step using the friction stir welding tool 1. Therefore, since the stirring force in the rotation axis direction increases, internal defects due to insufficient stirring can be eliminated, and the bonding strength can be increased. Moreover, since it is not necessary to process into the joining surface of a to-be-joined member, the cost of friction stir welding can be reduced.

Embodiment 7 FIG.
The friction stir welding method according to the seventh embodiment is the friction stir welding method according to the sixth embodiment in which the shoulder is not brought into contact with the upper surface of the first member to be joined when the probe of the friction stir welding tool is inserted in the insertion step. It is.
Hereinafter, the friction stir welding method of the seventh embodiment will be described with reference to the drawings of the first embodiment as appropriate based on FIG. 14 which is an explanatory diagram and FIG. 15 which is a comparative explanatory diagram.

  FIG. 14 is a schematic diagram of friction stir welding when the friction stir welding method of the seventh embodiment is applied using the friction stir welding tool of the present invention. FIG. 15 is a schematic diagram of friction stir welding when the friction stir welding method of the seventh embodiment is applied using a conventional friction stir welding tool.

  The joint width of the upper surface of the first member 5 to be friction stir welded is substantially equal to the diameter of the shoulder (see FIGS. 3 and 5). This is because, during the friction stir welding, the shoulder is pressed by the shoulder so that the joined portion of the first member to be joined 5 does not jump out.

  As described above, during friction stir welding, a load of several kN is applied to the friction stir welding tool. Therefore, if the shoulder diameter is excessively reduced, the friction stir welding tool is damaged. Moreover, the joint part which tries to jump out cannot be suppressed, and a burr | flash generate | occur | produces in large quantities. For this reason, it is difficult to reduce the diameter of the shoulder, and the friction stir welding has a large joining width.

  The friction stir welding method according to the seventh embodiment is a technique for joining the shoulder 2 without bringing the shoulder 2 into contact with the first member to be joined 5, and friction stir welding with a narrow joining width is possible (see FIG. 14). In addition, it is desirable that the clearance between the shoulder 2 and the first member to be bonded 5 is 0.1 to 0.5 mm.

  When a gap is provided between the shoulder 102 and the first member to be joined 5 using the conventional friction stir welding tool 101, a large amount of burr 111 is generated (see FIG. 15). Moreover, since the junction part of the 1st to-be-joined member 5 stirred cannot be suppressed, an internal defect arises in a junction part.

  When the friction stir welding tool of the present invention is used, as shown in FIG. 5, stirring is performed so that the joint portion on the upper surface of the first member 5 is pushed down. Therefore, as shown in FIG. 14, even if a gap is provided between the shoulder 2 and the first member 5, good bonding is possible without generating burrs.

  In the friction stir welding method according to the seventh embodiment, since the joining width does not depend on the diameter of the shoulder 2, the joining width can be reduced. This makes it possible to use friction stir welding even for narrow joints that could not be applied conventionally.

  As described above, in the friction stir welding method according to the seventh embodiment, when the probe of the friction stir welding tool is inserted in the insertion step, the shoulder is not brought into contact with the upper surface of the first member to be joined. Therefore, in addition to the effects of the sixth embodiment, the joint width can be narrowed, and the present invention can also be applied to a narrow joint that cannot be applied conventionally.

  Note that the present invention can be freely combined with each other within the scope of the invention, and the embodiments can be modified or omitted as appropriate.

1, 21, 31, 41, 51, 101, 121 Friction stir welding tool,
2,102,122 shoulder,
3, 23, 33, 43, 53, 103, 123 probes,
4, 104, 124 Tool holding part, 5 First member to be joined, 6 Second member to be joined,
7,107 bonding area, 8,108 upward stirring, 9,109 downward stirring,
110 Internal defect, 111 flash.

Claims (7)

A friction stir welding tool comprising a large-diameter shoulder and a small-diameter probe connected to the shoulder, the probe having a reverse tapered shape portion with a diameter decreasing toward the shoulder. The friction stir welding tool according to claim 1, wherein a diameter of a tip portion of the probe is smaller than a diameter of the probe at a connection portion with the shoulder. The friction stir welding tool according to claim 1, wherein the tip of the probe is chamfered and the tip is tapered. 4. The reverse tapered shape portion of the probe according to claim 1, wherein a maximum diameter of the reverse tapered shape portion is 1.1 to 2 times a minimum diameter of the reverse tapered shape portion. 5. Friction stir welding tool. The friction stir welding tool according to any one of claims 1 to 4, wherein a length of the probe is equal to or less than a minimum diameter of the probe. The probe connected to the shoulder uses a friction stir welding tool having a reverse tapered shape portion whose diameter is reduced toward the shoulder,
An insertion step of rotating the friction stir welding tool and inserting it between the first member to be joined and the second member to be joined;
While rotating the friction stir welding tool, a friction stir welding step of moving along the joining line and performing friction stir welding,
A drawing step in which the friction stir welding tool is rotated and pulled out from the first and second members to be joined;
A friction stir welding method comprising: The friction stir welding method according to claim 6, wherein in the inserting step, the shoulder is not brought into contact with the first member to be joined.

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