JP4346578B2 - Friction stir welding tool - Google Patents

Description

  The present invention relates to a friction stir welding tool that is joined by inserting a rotated stirring shaft into a joint portion where a pair of members to be joined are abutted and agitating while being softened by frictional heat. The present invention relates to a friction stir welding tool that prevents and extends the service life.

  In recent years, various friction stir welding methods have been proposed as new joining methods that replace metal welding and brazing. FIG. 5 is a diagram showing an outline of such a friction stir welding method. In this friction stir welding, as shown in the figure, the joining surfaces of a pair of plates 101 and 102 are butted as members to be joined. Then, the friction stir welding tool 110 having a stirrer shaft (probe) made of a material harder than the plates 101 and 102 is inserted along the joining line 200 where the butted joints are continuous while rotating at high speed. Then, a pair of plates 101 and 102 are agitated and joined while being plastically fluidized by frictional heat and pressure generated at the joining portion. Since such friction stir welding can be performed at a lower temperature than fusion welding or brazing, there is an advantage that there is little bonding failure due to thermal deformation at the time of bonding or oxidation of the bonded portion.

Incidentally, as a friction stir welding tool 110 used in the friction stir welding method, for example, Japanese Patent Application Laid-Open No. 2003-225777 proposes a tool having a stirrer as shown in FIG . The friction stir welding tool 110 includes a rotating body 111 coupled to a drive unit (not shown) of a rotary drive device, and a stirrer shaft (hereinafter referred to as “probe”) 112 that protrudes coaxially is formed at the tip. Has been. The probe 112 protrudes from the center of the end surface 113 of the rotating body 111 by a length corresponding to the thickness of the plates 101 and 102. A thread 115 is formed on the outer peripheral surface of the probe 112 at a portion excluding the root portion 114.

  Therefore, in the friction stir welding tool 110, the rotating body 111 and the probe 112 projecting from the tip of the rotating body 111 are rotated at a high speed by a rotation driving unit (not shown), and as shown in FIG. The probe 112 is inserted so as to press against the butting portion 102. Then, the end surface 113 of the rotating body 111 is pressed against the upper surfaces of the plates 101 and 102 and moves relatively along the joining line 200 in this state. As a result, as in the case described above, the joined portions of the plastic fluidized plates 101 and 102 are stirred and kneaded under the advance pressure of the probe 112, and after plastic flowing so as to wrap around the friction stir welding tool 110, It loses frictional heat rapidly and solidifies by cooling and joining.

By the way, in this friction stir welding tool 110, the root portion 114 and the screw thread 115 have different diameters and are provided with a step, and an R is formed at the connecting portion 116 between the probe 112 and the rotating body 111. Therefore, at the time of friction stir welding, the plates 101 and 102 are prevented from adhering to the root portion 114 of the probe 112, and the plates 101 and 102 do not float. Therefore, the stress 115 can be prevented from concentrating at the point where the screw thread 115 stops and the root portion 114 of the probe 112, so that the strength of the root portion 114 of the probe 112 is increased and the life of the friction stir welding tool is increased. Play.
JP 7-505090 A (page 2-6, FIG. 1) JP 2003-225777 A (page 2-3, FIGS. 1 and 2)

  By the way, the friction stir welding tool 110 or the like used in such a joining method is made of a material having sufficiently higher properties such as hardness, melting point, and wear resistance than the plate, and on the other hand, as shown in FIG. It is required that the thread 115 of the probe 112 can be formed. Therefore, conventionally, for example, die steel such as SKD material is used for the friction stir welding tool 110 and the like. However, even with such a material, the friction stir welding tool 110, particularly the probe 112, may be damaged or broken due to work under high temperature and high pressure during joining, or due to load fluctuations.

  If a part of the probe 112 is chipped or broken during the joining operation, a part of the probe 112 remains in the plate, and the burden of repair work including the recovery becomes large. For example, when a defect occurs in the joint due to a tool defect or the like, the repair must be performed by a method disclosed in, for example, Japanese Patent No. 3459193. The repair method is to remove a defect contained in the joint bead by grinding to form a repair region, and in the repair region, a repair bead is formed by TIG welding using a welding rod of the same material as the base material of the member. This is the method. However, when the friction stir welding tool was damaged or broken during the friction stir welding operation, it was unavoidable that even if the repair work was performed, the quality and appearance of the relevant part were deteriorated. .

  Accordingly, an object of the present invention is to provide a friction stir welding tool that enables long-life and good joining in order to solve such problems.

The friction stir welding tool according to the present invention has a columnar rotating body and a stirring shaft that is coaxially projected from the end face thereof, and the stirring shaft is rotated while rotating to a joint where a pair of members to be joined are abutted. Inserted and agitated and joined while being softened by the generated frictional heat, formed of SKD material or SKH material, and forming the outer shape of the rotary body and the stirring shaft, and a cemented carbide And a tool core member mounted on a rotating shaft in the tool outer shape member is integrally provided.

Further, the friction stir welding tool according to the present invention is a one-push type tool that presses an end face of a rotating body protruding from a stirring shaft against one surface of a member to be joined. It is preferable that an insertion hole is formed with a depth that opens to the tip end side of the shaft and enters the portion of the rotating body, and the tool core member is loaded and fixed in the insertion hole.
In the friction stir welding tool according to the present invention, the lower rotating body is integrally formed on the stirring shaft protruding from the end face of the rotating body, and the member to be joined is sandwiched between the rotating body and the lower rotating body. In the bobbin type tool, the tool outer member has an insertion hole formed at a depth that opens to the distal end side of the lower rotating body, penetrates the stirring shaft, and further enters a portion of the rotating body, It is preferable that the tool core member is loaded and fixed in the insertion hole .

Therefore, when joining a pair of to-be-joined members using the friction stir welding tool of the present invention, the rotating body and the stirring shaft rotate at a high speed, and the joined joint portion moves along the joining line. As a result, the joined part of the plastic fluidized member is stirred and kneaded under the advancing pressure of the stirring shaft, and plastically flows so as to go around the friction stir welding tool 1, and then rapidly loses the frictional heat and cools. Solidified and joined.
And, according to the friction stir welding tool of the present invention that repeats such friction stir welding, because the tool outer member formed of a highly tough material is reinforced from the inside with a tool core member formed of a highly rigid material, It is possible to suppress the load due to repeated loads and to extend the life compared to the conventional one, and to avoid the deterioration of the quality of the joint due to tool breakage or the like.

Next, an embodiment of a friction stir welding tool according to the present invention will be described below with reference to the drawings. FIG. 1 is a diagram conceptually showing the friction stir welding tool of the first embodiment.
This friction stir welding tool 1 is also used for friction stir welding in the same manner as described in the conventional example, and a stirring shaft is inserted into a joint where a pair of members to be joined are abutted with each other. When moving relatively along a continuous joining line, it is agitated and joined while plastically fluidizing by the generated frictional heat and pressure.

  The friction stir welding tool 1 includes a columnar rotating body 11 coupled to a driving unit of a rotation driving device (not shown), and a cylindrical stirring shaft (hereinafter referred to as a “probe”) protruding coaxially on an end surface 13 thereof. 12) is formed integrally. The probe 12 is formed from the center of the end face 13 of the rotating body 11 to a length corresponding to the thickness of the joined portion of the member to be joined. The friction stir welding tool 1 of the present embodiment is particularly characterized in that it is formed in a two-layer structure. That is, the friction stir welding tool 1 is composed of a tool outer member 1A constituting the outer shape thereof and a tool core member 1B inserted and fixed therein.

  By the way, in the conventional friction stir welding tool 110 shown in FIG. 6 and the like, as described above, die steel such as SKD material having high hot strength and good wear resistance is used as the material of the tool. However, there is a problem that the friction stir welding tool 110, in particular, the probe 112 may be damaged or broken due to a load variation repeatedly performed at a high temperature and a high pressure. Therefore, in order to solve such problems, it is conceivable to first make a material having higher fracture resistance and fracture resistance than conventional tools in order to increase the strength.

  However, in general, materials with high fracture resistance and fracture resistance (that is, high toughness) have low rigidity, and in situations where repeated load fluctuations are applied at high temperatures and high pressures during friction stir welding. Fatigue embrittlement tends to proceed and a sufficient tool life cannot be obtained. Therefore, it is considered that the probe 112 breaks due to fatigue due to repeated load when used for a long time. On the other hand, when a hard material with high rigidity is selected, it is difficult to process, and it becomes difficult to apply the thread 115 or the like as shown in FIG. 6 to the probe 112, resulting in an increase in processing cost. End up. Moreover, since a highly rigid material has a brittle surface against impact, it is not preferable to use it for a friction stir welding tool as it is.

Therefore, in the present embodiment, the friction stir welding tool 1 having a two-layer structure is proposed in consideration of such points. That is, the friction stir welding tool 1 uses a material having high toughness for the tool outer shape member 1A forming the outer shape, and uses a material having high rigidity for the tool core member 1B inserted and fixed therein. did. For example, tool steels such as SKD and SKH, which are conventionally used for friction stir welding tools, are used as the material having high toughness for forming the tool outer member 1A. On the other hand, a tool alloy such as a cemented carbide is used as the highly rigid material forming the tool core member 1B.

In the tool outer member 1A constituting the friction stir welding tool 1, the probe 12 is coaxially projected from the center of the end face 13 of the rotating body 11 with a length corresponding to the thickness of the member to be joined as described above. Further, the tool outer shape member 1A is formed in such an outer shape, and in addition, the shaft core portion is opened at the tip end side of the probe 12, and the insertion hole 14 is formed at a depth to enter the rotating body 11, so that the hollow shape is obtained. It has become. The insertion hole 14 is loaded with a cylindrical tool core member 1B made of cemented carbide.

The tool core member 1B is firmly fixed to the tool outer shape member 1A using a method such as brazing, shrink fitting, cold fitting, or welding, and integrated so as not to be easily separated during the joining operation. It has become. Thus, the friction stir welding tool 1 of the present embodiment increases the rigidity by placing the tool core member 1B at the center. Then, if the tool is formed only of the cemented carbide, it is not easy to process the threads on the probe. Therefore, a tool outer member 1A made of tool steel such as SKD or SKH is provided on the outside, and the probe 12 is provided. Surface processing such as a screw thread (not shown) is performed.

Therefore, according to the friction stir welding tool 1 having such a configuration, stir welding is performed as shown in FIG. 3, but the construction method is not different from the conventional case. That is, when the pair of plates 101 and 102 are joined, the rotating body 11 and the probe 12 projecting from the tip of the rotating body 11 are rotated at a high speed by a rotation driving unit (not shown), and the butted portions of the two plates 101 and 102 that are abutted are joined. The probe 12 is inserted so as to press against it. At this time, the end surface 13 of the rotating body 11 is pressed so as to pressurize the upper surfaces of the plates 101 and 102. The friction stir welding tool 1 moves relatively along the joining line 200 of the plates 101 and 102, and the joined portion of the plastic fluidized plates 101 and 102 receives the advancing pressure of the probe 12 and is agitated and kneaded. After the plastic flow so as to wrap around the friction stir welding tool 1, the frictional heat is rapidly lost to cool and solidify and join.

While such friction stir welding is repeated , the tool 1 for friction stir welding according to the present embodiment is made of tool steel such as SKD or SKH having a high toughness as in the case of conventional tools. The shaft core portion is reinforced with a tool core member 1B made of a cemented carbide with high rigidity. Therefore, the tool core member 1B supports the load that the probe 12 part receives during construction, and suppresses the load due to repeated loads. Therefore, in the present embodiment, the life of the friction stir welding tool 1 can be made longer than that of the conventional one, and further, it is possible to avoid deterioration of the quality of the joint due to tool breakage or the like. As the service life is extended, the number of tool replacements can be reduced and the cost can be reduced. Also, the frequency of repair work is reduced, and the cost can also be reduced in this respect.

Incidentally, the friction stir welding tools include those shown in FIG. 2 in addition to the types shown in FIG. FIG. 2 is a diagram conceptually showing the friction stir welding tool of the second embodiment. The friction stir welding tool 1 shown in FIG. 1 has a shape in which a probe 12 is simply protruded from a rotating body 11, and presses an end face 13 against a member to be joined to generate frictional heat during joining. Type. Therefore, in order to support the pressing load at the time of joining, a backing is necessary on the end side of the member to be joined. The friction stir welding tool 2 of the second embodiment is a bobbin type tool that does not require such backing.

In the friction stir welding tool 2, a stirrer shaft (hereinafter referred to as "probe") 22 protrudes coaxially from a cylindrical rotary member 21 coupled to a drive unit of a rotary drive device, and further, the probe 22 rotates downward. The body 23 is integrally formed. The present embodiment is also characterized in that it is formed in a two-layer structure, and includes a tool outer shape member 2A having an outer shape and a tool core member 2B inserted and fixed therein. For example, tool steel such as SKD or SKH is used for the tool outer shape member 2A as a material having high toughness, and a tool alloy such as cemented carbide such as cemented carbide is used for the tool core member 2B inserted and fixed therein as a material having high rigidity. Is used.

The outer shape of the tool outer shape member 2A is formed with a rotating body 21, a probe 12 and a lower rotating body 23. The lower end side of the lower rotating body 23 is opened at the shaft core portion. The insertion hole 24 is formed with a depth that penetrates through and enters the rotating body 21. The tool outer shape member 2A is formed in a hollow shape, and a cylindrical tool core member 2B made of cemented carbide is loaded into the insertion hole 24 thereof. The tool core member 2B is firmly fixed to the tool outer shape member 2A using a method such as brazing, shrink fitting, cold fitting, or welding, and integrated so as not to be easily separated during the joining operation. It has become. The friction stir welding tool 2 thus increases the rigidity by putting the tool core member 2B in the axial center portion, and the tool outer member 2A made of tool steel is subjected to surface processing such as a screw thread (not shown) on the probe 12. .

Therefore, when the pair of plates 101, 102 are joined by the friction stir welding tool 2 of the present embodiment as shown in FIG. 4, the rotating body 21 , the probe 22 and the lower rotating body 23 are moved at a high speed by a rotation driving unit (not shown). The probe 22 is inserted so as to press against the butted portions of the two plates 101 and 102 that are rotated and butted. The friction stir welding tool 2 relatively moves along the joining line 200 of the plates 101 and 102, and at this time, the plates 101 and 102 are sandwiched between the rotating body 21 and the lower rotating body 23. As the friction stir welding tool 2 is moved, the plastic fluidized plates 101 and 102 are agitated and kneaded by the advancing pressure of the probe 22 and are plastically flowed around the friction stir welding tool 2. After that, the frictional heat is rapidly lost to solidify by cooling and joining.

While such friction stir welding is repeated, the surface of the friction stir welding tool 2 of the present embodiment is made of tool steel such as SKD or SKH having high toughness as in the case of conventional tools. The shaft core portion is reinforced with a tool core member 2B made of a cemented carbide with high rigidity. Therefore, the tool core member 2B supports the load that the probe 22 portion receives during construction, and suppresses the load due to repeated loads. Therefore, in the present embodiment, the life of the friction stir welding tool 2 can be made longer than that of the conventional tool, and further, it is possible to avoid deterioration of the quality of the joint due to tool breakage or the like. As the service life is extended, the number of tool replacements can be reduced and the cost can be reduced. Also, the frequency of repair work is reduced, and the cost can also be reduced in this respect.

As mentioned above, although one Embodiment of the tool for friction stir welding which concerns on this invention was described, this invention is not limited to this, A various change is possible in the range which does not deviate from the meaning.

It is the figure which showed notionally the friction stir welding tool of 1st Embodiment. It is the figure which showed notionally the tool for friction stir welding of 2nd Embodiment. It is the figure which showed the joining method of the plate using the tool for friction stir welding of 1st Embodiment. It is the figure which showed the joining method of the plate using the tool for friction stir welding of 2nd Embodiment. It is a figure which shows the outline | summary of the friction stir welding method. It is sectional drawing which showed notionally the conventional tool for friction stir welding.

DESCRIPTION OF SYMBOLS 1 Friction stir welding tool 1A Tool external member 1B Tool core member 11 Rotating body 12 Probe 14 Insertion hole

Claims (3)

It has a cylindrical rotating body and an agitation shaft that projects coaxially from its end face, and is inserted into the joint where a pair of members to be joined are rotated while inserting the agitation shaft and softened by the generated frictional heat. In the friction stir welding tool to stir and join,
A tool outer member formed of an SKD material or an SKH material and constituting an outer shape of the rotating body and the stirring shaft; a tool core member formed of cemented carbide and loaded on the rotating shaft in the tool outer member; A tool for friction stir welding, characterized in that is integrally provided. In the friction stir welding tool according to claim 1,
It is a one-push type tool that presses the end face of the rotating body protruding from the stirring shaft against one surface of the member to be joined,
The tool outer member has an insertion hole formed at a depth that opens to the tip side of the stirring shaft and enters the rotating body, and the tool core member is loaded and fixed in the insertion hole. A friction stir welding tool characterized by the above. In the friction stir welding tool according to claim 1,
A bobbin type tool in which a lower rotating body is integrally formed on a stirring shaft protruding from an end surface of the rotating body, and a member to be joined is sandwiched between the rotating body and the lower rotating body,
The tool outer member has an insertion hole formed at a depth that opens to the distal end side of the lower rotating body, penetrates the stirring shaft, and further enters the rotating body portion, and the tool core member is inserted into the insertion hole. A tool for friction stir welding, characterized in that the tool is fixed by being loaded on the surface.

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