JP2005177844A - Friction stirring and joining method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a friction stirring and joining method which can join members to be joined without using a backing member. <P>SOLUTION: Each of members 21, 22 to be joined is joined each other while leaving an unfluidized portion 29 in a member 23 to be joined facing a joining tool 24 from the downstream side in the immersing direction. When the joining tool 24 presses the member 23 to be joined, a tool pressing force F1 of the joining tool 24 is transferred to the unfluidized portion 29. The unfluidized portion 29 has a higher deformation resistance than the fluidized portion 27. Plastic deformation of the member 23 to be joined can be suppressed by having the unfluidized portion 29 bear the tool pressing force F1. Thus, the friction stirring and joining can be performed without using the backing member. As the backing member is made unnecessary, the friction stirring and joining apparatus can be miniaturized and simplified so that manufacturing cost of the friction stirring and joining apparatus can be reduced. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a friction stir welding method for friction stir welding of objects to be joined.

  FIG. 23 is a cross-sectional view for explaining a conventional friction stir welding method. The article to be joined 23 forms the joint portion 5 by the two joined members 21 and 22 abutting each other. In the friction stir welding method, the welding tool 4 is slid on the joint portion 5 to generate frictional heat. And the to-be-joined object 23 is partially fluidized by friction heat, and the two to-be-joined members 21 and 22 are joined. In the prior art, the backing member 8 is brought into contact with the surface 7 on the opposite side to the welding tool 4 of the workpiece 23. This prevents the article 23 from being deformed during joining.

  FIG. 24 is a plan view showing the members 21 and 22 to be joined. When the gap 10 exists between the two members 21 and 22 to be abutted, there is a problem that the joint portion 5 that is joined is reduced in thickness and a joining defect occurs. In order to solve this problem, several methods for filling the gap 10 with powder or rod-like fillers have been proposed. In the method disclosed in Patent Document 1, the filler is temporarily joined by friction stir welding or welding to prevent the filler from jumping out of the gap 10 during joining.

JP 2000-233285 A

  As described above, in the conventional technique, the backing member 8 is brought into contact with the article to be joined 23 in order to prevent deformation of the article to be joined 23 at the time of joining. In this case, the backing member 8 is also enlarged with the increase in size of the article 23 to be joined. As a result, there is a problem that the friction stir welding apparatus is increased in size and weight, and the manufacturing cost is increased. Further, when the backing member 8 is formed in a roller shape, the size of the backing member 8 can be prevented, but there is a problem that the structure of the friction stir welding apparatus is complicated.

  Moreover, when joining each to-be-joined member 21 and 22 over the whole thickness direction A of the to-be-joined object 23, while preventing the contact with the joining tool 4 and the backing member 8, and joining each to-be-joined member 21 and 22 In order to prevent shortage, it is necessary to manage the distance 11 between the front-end | tip part of the joining tool 4 and the backing member 8 to 0.1-0.2 mm. However, it is difficult to accurately manage the distance 11.

  Accordingly, an object of the present invention is to provide a friction stir welding method that does not require the use of a backing member.

  Moreover, in the friction stir welding method disclosed in Patent Document 1, it is necessary to temporarily join the members to be joined 21 and 22 and the filler before the friction stir welding. In this case, there exists a problem that construction efficiency falls.

  Accordingly, another object of the present invention is to provide a friction stir welding method that prevents the filler from popping out without performing temporary bonding.

The present invention relates to a friction stir welding method in which a rotating joining tool is immersed in a workpiece constituted by a plurality of members to be joined, and each member to be joined is joined by frictional heat between the joining tool and a material to be joined. Because
First, the welding tool is immersed from one side in the thickness direction of the object to be bonded, and the non-fluidized portion that has not been fluidized is left in the other side in the thickness direction of the object to be bonded. 1 joining process,
A second joining step of joining each member to be joined in a state in which the joining tool is immersed from the other side in the thickness direction of the article to be joined and the non-fluidized portion is fluidized,
In the first joining step, the non-fluidized portion is left so that the non-fluidized portion has a deformation resistance capacity equal to or greater than the tool pressing force applied from the joining tool.

  According to the present invention, in the first joining step, each member to be joined is joined with the non-fluidized portion remaining. At this time, each member to be joined is partially joined in a state where the non-fluidized portion remains so as to have a deformation resistance greater than the tool pressing force. Accordingly, even when a tool pressing force is applied from the welding tool, plastic deformation in the other thickness direction of the workpieces can be suppressed. Moreover, both surfaces of each to-be-joined member can be joined by joining the thickness direction other side part of each to-be-joined member at a 2nd joining process.

  In the first joining step, the non-fluidized portion is cooled so that the non-fluidized portion has a deformation resistance greater than the tool pressing force.

  According to the present invention, by cooling the non-fluidized portion, softening of the non-fluidized portion due to frictional heat at the time of joining can be suppressed, and occurrence of joining deformation (strain) and joining defects can be suppressed. . Thereby, even if the dimension of the non-fluidized portion in the tool immersion direction is small, the deformation resistance ability of the non-fluidized portion at the time of joining can be made higher than the tool pressing force.

  In the first joining step, the present invention is characterized in that the thickness dimension of the non-fluidized portion is set so that the non-fluidized portion has a deformation resistance greater than the tool pressing force.

  According to the present invention, by setting the tool immersion direction dimension of the non-fluidized part, the deformation resistance ability of the non-fluidized part at the time of joining can be reduced even if the strength of the material itself forming the non-fluidized part is small. The pressing force can be exceeded.

  The present invention is characterized in that, in the first joining step and the second joining step, the thickness dimension of the fluidized portion for fluidizing the article to be joined is set to half or more of the thickness dimension of the article to be joined.

  According to the present invention, the non-fluidized portion remaining in the first joining step can be reliably fluidized in the second joining step, and each member to be joined is reliably joined over the entire thickness direction of the article to be joined. be able to. Thereby, the strength of the objects to be bonded after bonding can be improved.

  Further, according to the present invention, before immersing the joining tool, the filling material is formed by forming projecting portions projecting from both sides in the thickness direction of the article to be joined in the gap formed between the two joined members butted together. It is inserted, and the protruding part of the filler is bent with respect to the remaining part.

  According to the present invention, the filler is locked to the workpiece by inserting the filler into the gap and bending the portion protruding from the workpiece. This can prevent the filler from popping out of the gap during friction stir welding.

  Further, the present invention is characterized in that the filler is realized by a material having the same quality as the member to be joined or a material having a chemical property capable of joining each member to be joined.

  According to the present invention, it is possible to prevent the joint portion from being reduced in thickness and joining defects by the filler and to improve the joining strength of the members to be joined.

  Moreover, this invention is a continuous joining method which moves a joining tool along a butt | matching surface in the state which immersed the joining tool in the to-be-joined object, It is characterized by the above-mentioned.

  According to the present invention, the joining tool can be moved along the joining surface in a state in which the plastic deformation in the second direction in the thickness direction of the workpiece is suppressed in the second step.

  According to the present invention, plastic deformation of the workpiece can be suppressed by performing friction stir welding with the non-fluidized portion remaining. Thus, friction stir welding can be performed without using a backing member. By eliminating the need for the backing member, the friction stir welding apparatus can be reduced in size and simplified, and the manufacturing cost of the friction stir welding apparatus can be reduced.

  Even without using a backing member, in the second joining step, the joining tool can be immersed in the article to be joined in a state where there is no or little plastic deformation on the other side in the thickness direction of the article to be joined. As a result, the welding tool can be immersed in the target position without deviation. Further, the deformation of the objects to be joined after joining can be reduced. Thus, even if the backing member is not required, it is possible to prevent deterioration of the bonding quality.

  Further, in the conventional technology using the backing member, it was necessary to accurately manage the distance between the immersed joining tool and the backing member, but by eliminating the need for the backing member as in the present invention, It is not necessary to accurately manage the amount of immersion of the joining tool, and each member to be joined can be easily joined even if the dimension of the article to be joined varies slightly.

  According to the present invention, by cooling the non-fluidized portion, it is possible to suppress softening of the non-fluidized portion due to frictional heat at the time of joining and suppress a decrease in deformation resistance. Thereby, each member to be joined having a small thickness can be joined without using a backing member.

  Further, according to the present invention, by setting the dimension of the non-fluidized portion in the tool immersion direction, the deformation of the non-fluidized portion can be reduced even if the strength of the material itself forming the non-fluidized portion is small. . Thereby, the choice of the material of the to-be-joined member which can be joined without using a backing member can be increased.

  Moreover, according to this invention, each to-be-joined member can be joined over the whole thickness direction of a to-be-joined object by fluidizing the non-fluidization part which remained at the 1st joining process by the 2nd joining process. As a result, the bonding strength can be further improved.

  Further, according to the present invention, it is possible to prevent the filler from popping out at the time of joining only by bending the filler, and to save the trouble of temporarily fixing the filler. Thereby, the time spent for friction stir welding can be shortened. In addition, as above-mentioned, since it is not necessary to use a backing member, the filler inserted in the clearance gap between to-be-joined members can be bent easily. Further, the friction stir welding can be easily performed with the filler bent.

  Further, according to the present invention, the filler can prevent the thickness of the joint portion from being reduced or a joint defect, and the filler can contribute to the joining of the members to be joined. As a result, the quality and strength of the objects to be bonded after bonding can be improved.

  Moreover, according to this invention, a joining tool can be moved along a joining surface in the state which suppressed the plastic deformation to the other of the thickness direction of a to-be-joined object, without using a backing member. As a result, the joining tool can be moved along the travel path without deviation, and deterioration of the joining quality can be prevented. Conventionally, in the case of continuous joining, the backing member is enlarged according to the object to be joined, or is formed in a roller shape and complicated. In the present invention, since a backing member is not required, the effect of miniaturization and simplification of the friction stir welding apparatus is great.

  FIG. 1 is a flowchart showing a joining procedure of a friction stir welding method according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing a joining procedure according to an embodiment of the present invention, and FIGS. 3 and 4 are perspective views showing the joining procedure.

  Friction stir welding (abbreviated as FSW) of the present embodiment joins two members 21 and 22 to be joined. Each of the members to be joined 21 and 22 constitutes a member to be joined 23 in a state of being abutted. In the workpiece 23, the joint portion 28 is a portion where the two members 21 and 22 are abutted. The joint portion 28 extends linearly. In the present embodiment, the joining tool 24 is moved along the extending direction C of the joint portion 28 to join the members 21 and 22 to be joined, so-called continuous joining. Each member 21 and 22 is made of, for example, an aluminum alloy.

  The friction stir welding is performed using a friction stir welding apparatus (hereinafter simply referred to as a joining apparatus) that rotates and moves the welding tool 24. As shown in FIG. 2, the joining tool 24 includes a main body portion 25 formed in a substantially cylindrical shape, and a pin portion 26 that protrudes from the main body portion 25 in one axial direction and is formed in a substantially cylindrical shape. The main body 25 has a shoulder surface 30 that is an end surface on one side in the axial direction. The shoulder surface 30 is formed substantially perpendicular (+ 5 ° to −15 °) with respect to the axis L1 of the welding tool 24. The pin portion 26 projects vertically from the shoulder surface 30. The main body portion 25 and the pin portion 26 are formed coaxially, and the outer diameter of the pin portion 26 is smaller than the outer diameter of the main body portion 25.

  In the friction stir welding, in step a0, the operator holds the workpieces in a state where the two members 21 and 22 are abutted with each other by tack welding or a restraining jig. Further, the welding conditions such as the rotational speed of the welding tool 24, the amount of immersion of the welding tool 24, the moving speed of the welding tool 24, and the pressing force of the welding tool 24 are set. When the preparation related to the friction stir welding is completed in this way, the process proceeds to step a1, and the operator starts the friction stir welding operation using the joining device.

  In step a <b> 1, the operator makes the pin portion 26 of the welding tool 24 face the one surface 31 in the thickness direction of the workpiece 23. Further, the axis L1 of the welding tool 24 is arranged on the extended line of the boundary line 32 of the members 21 and 22 to be joined, and the process proceeds to step a2.

  In the present embodiment, the boundary line 32 between the members to be bonded 21 and 22 extends along the thickness direction A of the object to be bonded 23. Therefore, the axial direction of the welding tool 24 and the thickness direction A of the workpiece 23 coincide. Hereinafter, the thickness direction of the article 23 is simply referred to as the thickness direction.

  In step a2, as shown in FIG. 2 (1), the operator rotates the welding tool 24 around the axis L1 at a preset rotational speed, and proceeds to step a3. In step a3, as shown in FIG. 2 (2), the rotating welding tool 24 is immersed in the workpiece 23 from the one side A1 in the thickness direction of the workpiece 23 toward the other side A2 in the thickness direction.

  When the welding tool 24 rotates and immerses into the workpiece 23, frictional heat is generated and the workpiece 23 is partially fluidized. The fluidized first fluidized portion 27a of the members 21 and 22 constituting the workpiece 23 is stirred and mixed together. At this time, the welding tool 24 presses the workpiece 23 from the thickness direction one A1 side to the thickness direction other A2 side with a preset tool pressing force F1.

  In step a3, the welding tool 24 is immersed in the workpiece 23 by a predetermined first set immersion amount Z1. At this time, the shoulder surface 30 of the welding tool 24 is in sliding contact with the surface 31 on the one side in the thickness direction of the workpiece 23. The first set immersion amount Z1 is an amount by which the end surface 33 of the pin portion 26 is immersed in the workpiece 23 in the thickness direction A. In the present embodiment, the first set immersion amount Z1 is a dimension in the axial direction from the shoulder surface 30 to the end surface 33 of the pin portion 26.

  Of the joint portion 28, the first fluidized portion 27 a is formed on the one side A <b> 1 in the thickness direction, and the non-fluidized portion 29 that is not fluidized remains on the other side A <b> 2 in the thickness direction. The non-fluidized portion 29 faces the joining tool 24 from the other side A2 in the thickness direction. The dimension in the thickness direction of the non-fluidized portion 29 is set to a predetermined remaining plate amount Z2.

  For example, the first set immersion amount Z1 is set to be not less than half of the thickness direction dimension Z3 of the workpiece 23, and the remaining plate amount Z2 of the first fluidized portion 27a is not more than half of the thickness direction dimension Z3 of the workpiece 23. Set to In this way, when the first fluidizing portion 27a is sufficiently fluidized with the non-fluidized portion 29 remaining in the joint portion 28, the process proceeds to step a4.

  In step a4, as shown in FIG. 3, the joining tool 24 is moved along the extending direction C of the joint portion 28 while the joining tool 24 is rotated. Thus, the first fluidized portion 27a is formed on one side A1 in the thickness direction of the joint portion 28 while leaving the non-fluidized portion 29 on the other side A2 in the thickness direction of the joint portion 28 over the extending direction C. .

  When the welding tool 24 is moved over the entire extending direction C, the welding tool 24 is withdrawn from the workpiece 23, and the process proceeds to step a5. As the first fluidized portion 27a is hardened, the one-side A1-side portion in the thickness direction of the joint portion 28 is joined to the workpiece 23.

  Steps a1 to a4 are referred to as a first joining process. In the first joining step, in the workpiece 23, the upstream side in the tool immersion direction is the one side A1 in the thickness direction, and the downstream side in the tool immersion direction is the other side A2 in the thickness direction.

  In step a5, the operator changes the relative position between the welding tool 24 and the workpiece 23. Specifically, the pin portion 26 of the joining tool 24 is opposed to the other surface 34 in the thickness direction of the article 23 to be joined. Further, the axis L1 of the welding tool 24 is arranged on the extended line of the boundary line 32 of the members 21 and 22 to be joined, and the process proceeds to step a6.

  In step a6, as shown in FIG. 2 (3), the welding tool 24 is rotated around the axis L1 at the set rotational speed, and the process proceeds to step a7. In step a7, as shown in FIG. 2 (4), the rotating welding tool 24 is immersed in the workpiece 23 from the other thickness direction A2 side toward the thickness direction one A1 side. When the welding tool 24 rotates and immerses into the workpiece 23, frictional heat is generated and the workpiece 23 is partially fluidized.

  The fluidized second fluidized portion 27b of each of the members 21 and 22 constituting the workpiece 23 is agitated and mixed together. At this time, the welding tool 24 presses the workpiece 23 with a preset tool pressing force F2 from the other thickness direction A2 side to the thickness direction one A1 side.

  In step a6, the welding tool 24 is immersed in the workpiece 23 by a predetermined second set immersion amount Z4. At this time, the shoulder surface 30 of the welding tool 24 is in sliding contact with the other surface 34 in the thickness direction of the workpiece 23. The second set immersion amount Z4 is an amount by which the end surface 43 of the pin portion 26 is immersed in the workpiece 23 in the thickness direction A. In the present embodiment, it is the axial dimension from the shoulder surface 30 to the end surface 33 of the pin portion 26.

  The second fluidized portion 27 b is formed on the workpiece 23 on the other side A <b> 2 in the thickness direction of the joint portion 28. As a result, the non-fluidized portion 29 remaining on the other side A <b> 2 in the thickness direction of the joint portion 28 can be fluidized, and the fluidized portions 27 can be formed on both sides of the joint portion 28 in the thickness direction.

  For example, the second set immersion amount Z4 is set to be not less than half of the thickness direction dimension Z3 of the workpiece 23, and the remaining plate amount Z2 of the second fluidized portion 27b is not more than half of the thickness direction dimension Z3 of the workpiece 23. Set to In this way, when the second fluidized portion 27b formed on the other side A2 in the thickness direction is sufficiently fluidized, the process proceeds to step a8.

  In step a8, as shown in FIG. 4, the joining tool 24 is moved along the extending direction C of the joint portion 28 while the joining tool 24 is rotated. Thus, the second fluidization portion 27b formed on the other side A2 in the thickness direction of the joint portion 28 is formed over the extending direction C. When the joining tool 24 is moved over the entire extending direction C of the joint portion 28, the joining tool 24 is withdrawn from the workpiece 23, and the process proceeds to step a9. When the second fluidizing portion 27b is solidified, the other-side portion A2 in the thickness direction of the joint portion 28 is joined to the workpiece 23. In step a9, the joining operation is terminated.

  Steps a5 to a8 are referred to as a second joining step. In the second joining step, the tool immersing direction upstream side of the workpiece 23 is the other thickness direction A2 side, and the tool immersing direction downstream side is the thickness direction one A1 side.

  Moreover, you may change a tool rotation speed as needed before step a4 and a8. For example, the set rotational speed at the time of immersion is made higher than the traveling rotational speed. Thus, the amount of heat input from the joining tool to the object to be joined before the joining tool is immersed in the object to be joined can be increased, and the joining time can be shortened.

  In this embodiment, by performing the second joining step for joining the other A2 side in the thickness direction of the article 23 after the first joining step for joining the one A1 side in the thickness direction of the article 23 in this way. The two members 21 and 22 can be joined over the joint portion 28 across the thickness direction and over the extending direction C of the joint portion 28.

  In the first joining step, the joined members 21 and 22 are joined with the first non-fluidized portion 27a left. When the welding tool 24 presses the workpiece 23, the tool pressing force F1 of the welding tool 24 is given to the first non-fluidized portion 27a. The first non-fluidized portion 27a has greater deformation resistance, in other words, greater deformation resistance than the fluidized portion. By giving the tool pressing force F1 to the first non-fluidized portion 27a, plastic deformation of the workpiece 23 can be suppressed. Thus, friction stir welding can be performed without using a backing member. By eliminating the need for the backing member, the friction stir welding apparatus can be reduced in size and simplified, and the manufacturing cost of the friction stir welding apparatus can be reduced.

  Moreover, according to this Embodiment, the to-be-joined members 21 and 22 are continuously joined. Conventionally, in the case of continuous joining, the backing member is increased in size according to the object to be joined, or formed into a roller shape and complicated. In the present embodiment, since a backing member is not necessary, it is possible to more effectively realize downsizing and simplification of the friction stir welding apparatus.

  In addition, the second joining step may be a parallel operation by disposing the joining tool on the back side of the first joining step and slightly behind the position where the joining tool is immersed in the first joining step, that is, slightly downstream in the joining direction. Good. Thereby, the joining time can be shortened.

  Moreover, even if the to-be-joined object 23 deform | transforms a little in thickness direction other A2 at a 1st joining process, the influence of the deformation | transformation in a 1st joining process is made by immersing the joining tool 23 from the thickness direction other side at a 2nd joining process. Without joining, the members to be joined 21 and 22 can be joined.

  In the prior art using the backing member, it is necessary to accurately manage the distance between the immersed joining tool 24 and the backing member. However, by eliminating the need for the backing member as in the present invention. Therefore, it is not necessary to accurately manage the amount of immersion of the welding tool 24, and the members 21 and 22 can be bonded over the entire thickness direction of the workpiece 23 even if the dimensions of the workpiece 23 are slightly changed. it can.

  Moreover, the same joining tool 24 is used for the first joining step and the second joining step by setting the first set immersion amount Z1 and the second set immersion amount Z4 to half the thickness dimension of the workpiece 23. Can do. Moreover, each to-be-joined member 21 and 22 can be joined over the whole thickness direction direction of the to-be-joined object 23, and joining strength can be improved. Moreover, in this Embodiment, it is necessary to move the joining tool 24 over the extending direction C in both the thickness direction one A1 side and the other thickness direction A2 side. However, by setting the immersing amount of the welding tool 24 to half of the thickness dimension of the workpiece, the moving speed of moving in the extending direction C can be increased as compared with the case where the tool immersing amount is about the thickness dimension of the workpiece. Can be fast. As a result, it is possible to prevent the joining time from becoming significantly longer than in the prior art. Moreover, since the amount of tool immersion can be reduced, the load given to the welding tool 24 from the workpiece 23 can be reduced.

  FIG. 5 is an enlarged cross-sectional view illustrating the bonding state of the workpiece 23 after the first bonding step. As the remaining plate amount Z2 that is the dimension in the thickness direction of the non-fluidized portion 29 increases, the deformation resistance force of the non-fluidized portion 29 with respect to the force applied in the thickness direction A increases.

  The deformation resistance force of the non-fluidized portion 29 is a force applied to the non-fluidized portion 29 necessary for plastic deformation of the deformation amount δ1 of the non-fluidized portion 29 by the allowable deformation amount δ2. The deformation amount δ1 of the non-fluidized portion 29 is the deformation amount in the thickness direction of the deformation portion 35 that is the other end portion in the thickness direction. Further, the allowable deformation amount δ2 is the maximum deformation amount δ of the deformation portion 35 that is allowed as the joining quality. For example, the allowable deformation amount δ2 is such that when the pin portion 26 of the joining tool 24 abuts on the other surface 34 in the thickness direction of the workpiece 23 in the second joining step, the axis L1 of the pin portion 26 is from the joint portion 28. Set to an amount that does not deviate.

  In the present embodiment, the bonding strength of the non-fluidized portion 29 is set larger than the tool pressing force F1. As a result, when the pressing force F1 is applied from the welding tool 24, the deformation amount δ1 at which the deformed portion 35 of the non-fluidized portion 29 is deformed in the other thickness direction A2 is smaller than the allowable deformation amount δ2. When the deformation amount δ1 of the non-fluidized portion 29 is small, the same effect as the backing member in the prior art can be obtained by the non-fluidized portion 29. That is, the members 21 and 22 can be reliably bonded without using a backing member.

  FIG. 6 is a cross-sectional view showing a joined state of the comparative example. When the deformation resistance force of the non-fluidized portion 29 is smaller than the tool pressing force F1, the deformation amount δ1 of the deformed portion 35 of the non-fluidized portion 29 becomes larger than the allowable deformation amount δ2. Further, when the non-fluidized portion 29 is greatly deformed in the thickness direction other side A2, an opening P may be formed in the thickness direction other side A2 side surface 34 of the joint portion 28.

  The deformation resistance force V in the thickness direction of the non-fluidized portion 29 changes in relation to at least the tensile strength σ of the material constituting the non-fluidized portion 29 and the remaining plate amount Z2. Therefore, by setting the tensile strength σ and the remaining plate amount Z2 so that the deformation resistance force V is equal to or greater than the tool pressing force F1, friction stir welding can be performed without using a backing member.

In general, the deformation resistance V is expressed by the following equation.
V∝α ・ σ (t) ・ Z2
Here, ∝ represents that the numerical values on both sides are in a proportional relationship. V represents the deformation resistance, α is a coefficient depending on the shape of the joining tool 24 and the temperature gradient of the remaining plate amount Z2, and σ (t) represents the tensile strength. However, the tensile strength σ (t) is a variable that varies with temperature. Z2 represents the remaining plate amount.

  In other words, the deformation resistance V is roughly proportional to a value obtained by multiplying the coefficient α, the tensile strength σ (t), and the remaining plate amount Z2. In order to eliminate the need for the backing member, it is necessary that the tool pressing force F1 <the deformation resistance force V. In other words, it is necessary to set at least one of the tensile strength σ (t) and the remaining plate amount Z2 so that the deformation resistance force V becomes larger than the tool pressing force F1.

  Further, if the deformation amount δ1 of the non-fluidized portion 29 is equal to or less than a predetermined allowable deformation amount δ2, the second joining step is not affected. For example, the allowable deformation amount δ2 is about 1.0 mm. In the friction stir welding, if the material to be fluidized is sufficiently sandwiched between the fluidized portion 29 and the shoulder portion and is not stirred in a pressurized state, the deformation amount δ1 of the fluidized portion 29 is an allowable deformation. When the amount δ2 is exceeded, a bonding defect occurs. For example, as a bonding defect, there are generation of distortion of the object 23 after bonding, formation of an immersion trace of the bonding tool, generation of a cavity in a fluidized portion, and reduction in thickness of the bonded portion.

  7-10 is sectional drawing which shows the experimental result of the to-be-joined object in the state which finished the 1st joining process. 7 and 8 show a case where a material annealed with an aluminum alloy indicated by an alloy number 5083 defined by Japanese Industrial Standards, so-called 5083-O, is used as each of the members 21 and 22 to be joined. 7 to 10, the boundary between the first fluidized portion 27a and the non-fluidized portion 29 is exaggerated for clarity. 7 and 8 show the case where the thickness dimension Z3 of the workpiece 23 is 10 mm.

  FIG. 7 shows a case where the remaining plate amount Z2 is set satisfactorily. When the first set immersion amount Z1 is 4 mm, the deformation amount δ1 of the non-fluidized portion 29 is 0.8 mm, which is smaller than the allowable deformation amount δ2.

  FIG. 8 shows a case where the remaining plate amount Z2 is not good. When the first set immersion amount Z1 is 6 mm, the deformation amount δ1 of the non-fluidized portion 29 is 4.6 mm, which is larger than the allowable deformation amount δ2. In addition, the object to be bonded 23 is greatly raised on the downstream side in the bonding direction, and the opening P is formed between the members to be bonded 21 and 22, so that the bonding quality is deteriorated.

  9 and 10 show the case where the thickness dimension Z3 of the workpiece 23 is 20 mm. FIG. 9 shows a case where the remaining plate amount Z2 is set satisfactorily. When the first set immersion amount Z1 is 10 mm, the deformation amount δ1 of the non-fluidized portion 29 is 0.2 mm, which is smaller than the allowable deformation amount δ2.

  FIG. 10 shows a case where the remaining plate thickness Z2 is not good. When the first set immersion amount Z1 is 15 mm, the deformation amount δ1 of the non-fluidized portion 29 is 1.8 mm, which is larger than the allowable deformation amount δ2. Moreover, a void | hole and a recess are formed in the 1st fluidization part 27a, and joining quality falls.

  As shown in FIGS. 9 to 10, the remaining plate amount Z2 is set to exceed the critical remaining plate amount Z5 determined by the bonding conditions such as the material of the members to be bonded 21 and 22, thereby maintaining the bonding quality. In addition, the friction stir welding can be performed without using a backing member. The allowable deformation amount δ2 and the critical remaining plate amount Z5 may be obtained by a test or by numerical analysis.

  In the first joining step and the second joining step, when the joining tool 24 having the same shape is used, the first set immersive amount Z1 and the second set immersive amount Z4 have the same value. In this case, in order to join over the entire thickness direction in the joint direction 28, the first set immersion amount Z1 and the second set immersion amount Z4 are set to be more than half of the thickness direction dimension Z3 of the workpiece 23. Here, when the first set immersion amount Z1 is set to be not less than half of the dimension Z3 in the thickness direction of the workpiece 23 and the remaining plate amount Z2 is equal to or less than the critical remaining plate amount Z5, the non-fluidized portion By cooling 29, a backing member can be made unnecessary.

  FIG. 11 is a graph showing the temperature change at the other end in the thickness direction of the non-fluidized portion 29. The temperature of the workpiece 23 increases with time due to frictional heat applied from the welding tool 24. The non-fluidized portion 29 reaches a maximum of 300 ° C. during friction stir welding. As the temperature rises, the tensile strength of the article 23 decreases.

Table 1 shows the tensile strength, yield strength and elongation at each temperature in the aluminum alloy represented by alloy symbol 5083-O. According to Table 1, aluminum alloys, cold, for example, tensile strength at 25 ° C., a tensile strength of at but 315 ° C. is 290 N / mm ² is 75N / mm ^2. By cooling the back surface side of the non-fluidized portion 29 to 100 ° C. during the friction stir welding, the tensile strength can be set to 275 N / mm ² . On the other hand, if the non-fluidized portion is cooled too much, the amount of heat input at the joining portion will be insufficient. In this case, joint defects and tool breakage due to insufficient heat input occur.

  By cooling the non-fluidized portion 29 in this way, the tensile strength of the non-fluidized portion 29 can be improved, and the deformation resistance force V can be increased. Accordingly, even when the remaining plate amount Z2 is small, the deformation resistance force V of the non-fluidized portion 29 can be made equal to or greater than the pressing force F1 of the joining tool, and the deformation amount of the non-fluidized portion 29 at the time of joining. δ1 can be set to an allowable deformation amount δ2 or less.

  FIG. 12 is a cross-sectional view showing a joining device 50 including the cooling means 51. When cooling the non-flow part 29 at the time of friction stir welding, friction stir welding is performed using the joining apparatus 50 provided with the cooling means 51. The joining device 50 includes a tool holding means 41, a rotation driving means 42, a pressing drive means 43, a continuous movement means 44, a work holding means 52, a cooling means 51, and a control means 45. .

  The tool holding means 41 holds the joining tool 24 in a detachable manner. The joining tool 24 mounted on the tool holding means 41 is arranged so that its axis is coaxial with the tool holding means 41. The tool holding means 41 is provided to be rotatable around the axis L1. The tool holding means 41 is provided so as to be displaceable along the axis L1. The tool holding means 41 is provided so as to be displaceable along the extending direction of the joint portion 28 of the workpiece 23 held by the work holding means 52.

  The rotation driving means 42 drives the tool holding means 41 to rotate about its axis L1. The rotation driving means 42 is realized by, for example, an induction motor or a servo motor. The electric motor is controlled by the control means 45. In this case, the control means 45 adjusts the current given to the motor.

  The displacement driving means 43 drives the tool holding means 41 to move in the reference axis direction A. The pressing drive means 43 drives the tool holding means 41 to be displaced in the axial direction. The pressing drive means 43 is realized by, for example, a backward-acting air cylinder. The air cylinder is controlled by the control means 45. In this case, the control means 45 adjusts the supply path and supply state of the compressed air supplied to the cylinder.

  The continuous moving means 44 drives the tool holding means 41 to be displaced along the extending direction C of the joint portion 28 of the workpiece 23. The continuous movement means 44 has a support part that supports the tool holding part 41, a rail mechanism that guides the support part in the extending direction, and a traveling means that moves the support part in the extending direction. The support portion cantilever-supports the tool holding portion 41 from above. The rail mechanism includes a rail extending in the reference axis direction A in the extending direction, and a guide body guided by the rail. The guide body is provided so as to be displaceable in the extending direction, and displacement in other directions is prevented. The support portion is connected to the guide body. The tool holding portion 41 can be moved in the extending direction together with the support portion by driving the support portion to be displaced by the traveling means.

  The work holding means 52 holds the workpiece 23 in a state in which the respective joining surfaces of the joined members 21 and 22 are abutted. In the work holding means 52, a backing member that contacts the joint portion 28 is omitted. As a result, the joint portion 28 is formed with spaces on both sides in the thickness direction while being held by the work holding means 52. The work holding means 52 abuts the object to be bonded 23 at any part except the joint portion 28, and supports the object to be bonded from below.

  The cooling means 51 cools the workpiece 23 from the side opposite to the joining tool immersion direction. Specifically, the cooling means 51 includes an air supply source 51a and an air ejection nozzle 51b. The air supply source 51a compresses normal temperature air or air cooled to normal temperature and supplies the compressed air to the air ejection nozzle 51b. The air ejection nozzle 51b ejects air supplied from the air supply source 51a from the ejection section. The ejection portion is arranged to face the lower surface of the joint portion 28 in the tool immersion direction. As a result, the non-fluidized portion 29 can be efficiently cooled. The ejection portions are provided at a plurality of locations side by side in the extending direction C of the joint portion 28. The timing at which the cooling means 51 ejects air is controlled by the control means 45.

  The control means 45 includes an input unit, an output unit, a storage unit, and a calculation unit. The input unit receives a command from the operator and gives the input command to the calculation unit. The input unit may receive a set value related to friction stir welding from an operator.

  The input unit is realized by a button or the like. The output unit outputs a calculation result calculated by the calculation unit. Specifically, the output unit gives a drive command and a stop command to the rotation drive unit 42, the press drive unit 43, and the continuous movement unit 44. The storage unit stores a predetermined calculation program and stores a calculation result calculated by the calculation unit. The calculation unit reads and executes the calculation program stored in the storage unit. The calculation unit gives a command to the output unit according to a predetermined friction stir welding procedure by executing the calculation program. For example, the storage unit is realized by a RAM (Random Access Memory) and a ROM (Read Only Memory). Further, for example, the calculation unit is realized by a CPU (Central Processing Unit). Such a joining apparatus 50 can also be used for the friction stir welding shown in FIGS. 1 and 2.

  An operator performs a 1st joining process and a 2nd joining process with such a joining apparatus 50. FIG. The control means 45 causes air to be ejected from the air ejection nozzle 51b at least while the welding tool 24 applies the tool pressing force F1 to the workpiece 23. As a result, the fluidized portion 29 of the workpiece 23 is cooled, and the deformation resistance of the non-fluidized portion 29 is improved. By cooling the non-fluidized portion 29 in this manner, the amount of immersion of the joining tool 24 can be increased compared to the case where the non-fluidized portion 29 is not cooled.

  Thereby, even when the dimension in the thickness direction of the workpiece 23 is thin and the remaining plate amount Z2 in the first joining process cannot be increased, the deformation of the non-fluidized portion 29 is suppressed, The members 21 and 22 to be joined can be joined. As a result, the options of the members 21 and 22 that can be joined without using a backing member can be expanded.

  FIG. 13 is a cross-sectional view showing the results of numerical analysis under the joining conditions shown in FIG. FIG. 13 (1) is an axisymmetric model showing the temperature distribution, and FIG. 13 (2) is an axisymmetric model showing the deformation state. When the joining conditions in FIG. 8, that is, the remaining plate amount Z2 is 10 mm, the temperature of the deformed portion 35 of the non-fluidized portion 29 exceeds 300 ° C. and becomes 400 ° C. or less. Further, the deformation amount δ1 of the non-fluidized portion 29 is calculated as 0.44 mm. In this case, as shown in the experimental results of FIG. 7, no defect occurs in the bonded object 23 after bonding.

  FIG. 14 is a cross-sectional view showing the numerical analysis results under the joining conditions of FIG. FIG. 14 (1) is an axisymmetric model showing the temperature distribution, and FIG. 14 (2) is an axisymmetric model showing the deformation state. When the joining conditions of FIG. 8, that is, the remaining plate amount Z2 is 5 mm, the temperature of the deformed portion 35 of the non-fluidized portion 29 exceeds 300 ° C. and becomes 400 ° C. or less. The deformation amount δ1 of the non-fluidized portion 29 is calculated as 0.93 mm. In this case, as shown in the experimental result of FIG. 8, a defect occurs in the bonded object 23 after bonding.

  FIG. 15 is a cross-sectional view showing a numerical analysis result when the deformed portion 35 of the non-flow portion is cooled to about 100 ° C. as compared with the joining condition of FIG. FIG. 15 (1) is an axisymmetric model showing the temperature distribution, and FIG. 15 (2) is an axisymmetric model showing the deformation state. When the temperature of the deformed portion 35 of the non-fluidized portion 29 is cooled to more than 100 ° C. and not more than 200 ° C. as compared with the joining conditions of FIG. δ1 is calculated as 0.29 mm.

  FIG. 16 is a cross-sectional view showing a numerical analysis result when the deformed portion 35 of the non-flow portion is cooled to about 200 ° C. as compared with the joining condition of FIG. FIG. 16 (1) is an axisymmetric model showing the temperature distribution, and FIG. 16 (2) is an axisymmetric model showing the deformation state. When the temperature of the deformed portion 35 of the non-fluidized portion 29 is cooled to over 300 ° C. and below 300 ° C. as compared with the joining conditions of FIG. δ is calculated as 0.72 mm.

  As shown in FIG. 13, when the deformation amount δ is calculated as 0.44 mm from the numerical analysis result, the experimental result shows that no defect occurs in the bonded object 23 after bonding. Assume that the critical deformation δ at which defects occur is 0.45 mm.

  In this case, as shown in FIG. 15, when the remaining plate amount Z2 is 5 mm, the deformation amount δ when the non-flow portion 29 is cooled to over 200 ° C. and below 100 ° C. is calculated as 0.29 mm. Therefore, it is presumed that no defect occurs in the bonded object 23 after bonding. Further, as shown in FIG. 16, when the remaining plate amount Z2 is 5 mm, the deformation amount δ when the non-fluidized portion 29 is cooled to over 300 ° C. and below 300 ° C. is calculated as 0.72 mm. When the remaining plate amount Z2 is 5 mm, there is a possibility that a defect occurs in the bonded object 23 after the bonding.

  Thus, the deformation amount δ1 of the non-fluidized portion 29 when the non-fluidized portion 29 is cooled is calculated by numerical analysis, and the temperature of the non-fluidized portion 29 when the allowable deformation amount δ2 or less is calculated. Then, by cooling the non-fluidized portion 29 to that temperature, it is possible to eliminate defects in the article 23 after joining even when the remaining plate amount Z2 is small.

  FIG. 17 is a plan view showing the article 23 to be filled with the filler 60. In some cases, the gaps U1 and U2 are formed between the objects to be bonded 23 in a state where the members 21 and 22 are abutted. In the present embodiment, the filler 60 is inserted into the gaps U1 and U2 before joining. The filler 60 is made of a material that is fluidized by friction stir welding. The filler 60 is preferably a sheet rolled material made of the same material as the members 21 and 22 to be joined. For example, in the case of the present embodiment, the joined members 21 and 22 are made of an aluminum alloy, and the filler 60 is realized by an aluminum wire for welding. For example, the filler 60 is an annealed JIS-Z-3232 filler rod or welding wire defined by Japanese Industrial Standards. Further, the filler 60 may be realized by a material having chemical properties capable of joining the members to be joined, even if they are not the same as the members to be joined.

  FIG. 18 is a cross-sectional view of FIG. 17 as seen from the line AA. In the friction stir welding procedure, the operator inserts the filler 60 into the gap U <b> 1 between the members to be joined 21 and 22 in a state where the members to be joined 21 and 22 are abutted. The filler 60 is filled so as to fill the gap U1. At this time, the filler 60 is formed with projecting portions 61 and 62 projecting on both sides A1 and A2 in the thickness direction of the workpiece 23, respectively. The protruding portions 61 and 62 are formed to bend in the direction B intersecting the thickness direction A with respect to the remaining portion 63. In the present embodiment, both end portions 61 and 62 in the longitudinal direction of the filler 60 are bent in the same direction and are formed in a substantially U shape.

  FIG. 19 is a cross-sectional view of FIG. 17 as viewed from the line BB. When the gap U3 is formed between the filler 60 and the joined members 21 and 22 with the filler 60 formed in a substantially U shape inserted, as shown in FIG. In addition to the first filler 60 formed in a letter shape, a second filler 66 that fills the gap U3 may be inserted. In order to prevent the second filler 64 from jumping out from the gap U <b> 3 during joining, it is preferable to cover the second filler 64 with the bent portions 61 and 62 of the first filler 60.

  FIG. 20 is a cross-sectional view showing another second filler 65. Instead of the second filler 64 described above, a powder filler 65 may be filled in the gap U3 between the first filler 63 and the members 21 and 22 to be joined. As in the case described above, the powder filler 65 is covered with the bent portions 61 and 62 of the first filler 63 in order to prevent the powder filler 60 from jumping out of the gap U3 during joining. preferable. The filler 63 is preferably annealed so that it can be easily bent.

  FIG. 21 is a cross-sectional view showing a friction stir welding procedure in the case where the filler 60 is filled. As shown in FIG. 21 (1), when the gap U1 is formed in a state where the workpiece 23 is joined, the filler 60 is inserted into the gap U1 as shown in FIG. 21 (2). As the filler 60, a material having a longitudinal dimension Z6 longer than the thickness dimension Z3 of the workpiece 23 is used. One end 61 in the longitudinal direction of the filler 60 is projected from the thickness direction one A1 with respect to the workpiece 23, and the other end 62 in the longitudinal direction is projected from the other thickness A2 with respect to the workpiece 23.

  Next, as shown in FIG. 21 (3), both longitudinal ends 61 and 62 of the filler 60 are bent with respect to the remaining portion 63 to form the filler 60 in a substantially U shape. In this state, the same operations as in steps a1 to a10 described above are performed. By performing the first joining step, as shown in FIG. 21 (4), friction heat is applied to the filler 60 together with the article to be joined 23, and the one A1 side portion in the thickness direction is fluidized. Next, by performing a second joining step, as shown in FIG. 21 (5), friction heat is given to the filler 60 together with the article to be joined 23, and the other A2 side portion in the thickness direction is fluidized.

  By bending the filler 60 as in the present embodiment, the bent portions 61 and 62 of the filler 60 are locked to the workpiece 23, and the filler 60 is prevented from popping out during friction stir welding. it can. Accordingly, it is not necessary to temporarily join the filler 60, the thickness of the joined joint portion 28 can be reduced, the occurrence of joining defects can be reduced, and the joining quality can be further improved.

  In the present embodiment, a backing member can be dispensed with. Thus, as shown in FIG. 12, spaces can be formed on both sides in the thickness direction of the joint portion 28 in a state where the workpieces 21 and 22 are brought into contact with each other by the work holding means 52. Thereby, the insertion operation of the filler 60 into the gap U1 and the bending operation of both ends of the filler 60 can be easily performed. Further, since the joining operation is performed in a state where spaces are formed on both sides in the thickness direction of the joint portion 28, the bent portions 61 and 62 of the filler 60 do not hinder the first joining step.

  FIG. 22 is a cross-sectional view showing another bending state of the filler 60. When the gap U1 is large, as shown in FIG. 22, with the plurality of fillers 60 inserted into the gap U1, one end in the first direction intersecting the longitudinal direction end 61 of each filler 60 in the thickness direction and The first direction is bent in the other direction. Similarly, the other end 62 in the longitudinal direction of each filler 60 is bent to both sides in the first direction intersecting the thickness direction. Thereby, it is bent in an X shape by a plurality of fillers. Even when bent in this way, the object 23 can be bonded.

  The above-described friction stirring method according to the embodiment of the present invention is an example of the invention, and the configuration can be changed within the scope of the invention. For example, the members to be bonded 21 and 22 may be overlapped to constitute the object to be bonded 23 in addition to being abutted. Moreover, in this Embodiment, although the to-be-joined members 21 and 22 were faced | matched and joined to the thickness direction A of the to-be-joined object 23, they are faced | butted in width direction or a longitudinal direction other than the thickness direction of the to-be-joined object 23, for example. The members to be joined may be joined. In addition to continuous bonding, spot bonding may be used. Moreover, although the to-be-joined members 21 and 22 are aluminum alloys, other materials may be used.

  Moreover, in this Embodiment, although the to-be-joined members 21 and 22 were joined over the thickness direction A whole region of the to-be-joined object 23, in temporary joining etc., you may join only thickness direction one A1. That is, the case where only the first bonding step is performed also belongs to the present invention. Even in this case, the joined members 21 and 22 can be partially joined without using a backing member. Further, the joining conditions such as the shape of the joining tool 24 may be changed between the first joining process and the second joining process.

It is a flowchart which shows the joining procedure of the friction stir welding method which is one Embodiment of this invention. It is sectional drawing which shows the joining procedure which is one Embodiment of this invention. It is a perspective view which shows a joining procedure. It is a perspective view which shows a joining procedure. It is sectional drawing which expands and shows the joining state of the to-be-joined object 23 which finished the 1st joining process. It is sectional drawing which shows the joining state of a comparative example. It is sectional drawing which shows the experimental result of the to-be-joined object in the state which finished the 1st joining process. It is sectional drawing which shows the experimental result of the to-be-joined object in the state which finished the 1st joining process. It is sectional drawing which shows the experimental result of the to-be-joined object in the state which finished the 1st joining process. It is sectional drawing which shows the experimental result of the to-be-joined object in the state which finished the 1st joining process. It is a graph which shows the temperature change of the thickness direction other end part of the non-fluidization part 29. FIG. It is sectional drawing which shows the joining apparatus 50 provided with the cooling means 51. FIG. It is sectional drawing which shows the numerical analysis result in the joining conditions of FIG. It is sectional drawing which shows the numerical analysis result in the joining conditions of FIG. It is sectional drawing which shows the numerical analysis result in case the deformation | transformation part 35 of a non-flow part is cooled to about 100 degreeC compared with the joining conditions of FIG. It is sectional drawing which shows the numerical analysis result in case the deformation | transformation part 35 of a non-flow part is cooled to about 200 degreeC compared with the joining conditions of FIG. It is a top view which shows the to-be-joined object 23 with which the filler 60 is filled. It is sectional drawing which looked at FIG. 17 from the AA cut surface line. It is sectional drawing which looked at FIG. 17 from the BB cut surface line. It is sectional drawing which shows the other 2nd filler 65.

It is sectional drawing which shows the friction stir welding procedure in the case of filling the filler 60. FIG. 6 is a cross-sectional view showing another bent state of the filler 60. It is sectional drawing for demonstrating the friction stir welding method of a prior art. It is a top view which shows the to-be-joined members 21 and 22 butt | matched.

Explanation of symbols

21, 22 Member to be joined 23 Object to be joined 24 Joining tool 27 Fluidizing portion 28 Joint portion 29 Non-fluidizing portion 60 Filler A Thickness direction A1 Thickness direction one A2 Thickness direction other

Claims (7)

A friction stir welding method in which a rotating welding tool is immersed in a workpiece constituted by a plurality of members to be joined, and each member to be joined is joined by frictional heat between the welding tool and the workpiece material,
First, the welding tool is immersed from one side in the thickness direction of the object to be bonded, and the non-fluidized portion that has not been fluidized is left in the other side in the thickness direction of the object to be bonded. 1 joining process,
A second joining step of joining each member to be joined in a state in which the joining tool is immersed from the other side in the thickness direction of the article to be joined and the non-fluidized portion is fluidized,
In the first joining step, the non-fluidized portion is left so that the non-fluidized portion has a deformation resistance greater than the tool pressing force applied from the joining tool.   2. The friction stir welding method according to claim 1, wherein in the first joining step, the non-fluidized portion is cooled such that the non-fluidized portion has a deformation resistance greater than the tool pressing force.   The friction stir welding according to claim 1 or 2, wherein in the first joining step, the thickness dimension of the non-fluidized portion is set so that the non-fluidized portion has a deformation resistance greater than the tool pressing force. Method.   4. The method according to claim 1, wherein in the first joining step and the second joining step, the thickness dimension of the fluidized portion for fluidizing the article to be joined is set to be half or more of the thickness dimension of the article to be joined. The friction stir welding method according to one.   Before immersing the welding tool, the filler is inserted into the gap formed between the two workpieces that are butted against each other by forming protruding portions that protrude from both sides in the thickness direction of the workpiece. 5. The friction stir welding method according to any one of claims 1 to 4, wherein the protruding portion is bent with respect to the remaining portion.   6. The friction stir welding method according to claim 5, wherein the filler is realized by a material having the same quality as the members to be joined or a material having chemical properties capable of joining the members to be joined.   The friction stir welding method according to any one of claims 1 to 6, wherein the welding tool is a continuous welding method in which the welding tool is moved along the abutting surface while the welding tool is immersed in the workpiece.

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