JP7102900B2 - Friction stir welding method - Google Patents

Description

The present invention relates to a friction stir welding method.

For example, as described in Patent Document 1 below, a method of friction stir welding of two metal members is known. In the first step (butting step) of this friction sales expansion joining method, first, the end faces of two metal members (first member and second member) as joining target members are butted. Both members are arranged so that a step is not formed at the boundary between the first member and the second member. In the second step (joining step), the tip end portion (probe portion) of the friction stir welding tool is press-fitted into the friction stir welding target portion and scanned along the friction stir welding target portion. As a result, the friction stir welding target portion (that is, the portions located on both sides of the abutted end faces) is agitated and plastically flows. In this way, the first member and the second member are joined.

Japanese Unexamined Patent Publication No. 2016-74014

Generally, when the friction stir tool is scanned along the friction stir welding target site, the central axis of the friction stir welding tool is not perpendicular to the surface of the friction target site but slightly inclined with respect to the surface (or normal). There is. That is, the tip side (probe portion side) of the friction stir tool is located in front of the base end side (shank portion side) in the scanning direction. The angle of inclination of the central axis with respect to the normal is called the forward angle. The advance angle is set to, for example, 3 °. As described above, by arranging the friction stir tool at an angle with respect to the normal, the latter half side in the scanning direction of the shoulder portion (tip of the shank portion) of the friction stir tool is compared with the first half side. Then, it penetrates deeply into the part to be joined. Therefore, it is possible to suppress the floating (swelling of the surface) of the metal material that has been agitated by the friction stir tool and plastically flowed to the rear side in the scanning direction, and suppress the occurrence of joint defects (cavities).

Here, as shown in FIG. 22, a process of joining the first friction stir welding target portion WP1 of the abutted first member P1 and the second member P2 and subsequently joining the second friction stir welding target portion WP2 will be considered. do. The outer peripheral surface S1 of the first friction stir welding target portion WP1 is flat, and the outer peripheral surface S2 of the second friction stir welding target portion WP2 is an arc surface continuous with the outer peripheral surface S1.

First, the friction stir tool FT is press-fitted into the first friction stir welding target portion WP1. Then, the friction stir tool FT is translated to the WP2 side (right side in FIG. 23) of the second friction stir welding target portion. In the joining step of the first friction stir welding target portion WP1, the advance angle θ is set to a predetermined value (for example, 3 °). In other words, the depth d of the latter half of the shoulder portion into the first friction stir welding target portion WP1 is set to an optimum value d ₀ (for example, 0.3 mm) capable of suppressing the lifting of the plastically fluidized metal material. To. The tip (probe portion) of the friction stir tool FT is actually a conical trapezoid, but in the following description, the tip DP of the probe portion PR is a sharp shape. Further, in FIG. 23, the broken line La represents a position where the distance from the outer peripheral surfaces S1 and S2 is the optimum value _d0 of the depth d. Further, the broken line Lb represents a position where the distance from the outer peripheral surfaces S1 and S2 is the optimum value _D0 of the stirring depth D.

As shown in FIG. 23, when the tip DP of the probe portion PR reaches the boundary portion BD ₁₂ between the first friction stir welding target portion WP1 and the second friction stir welding target portion WP2, the friction stir welding tool FT moves to the outer circumference. It begins to rotate around the central axis O of the surface S2. Here, the rotation angle α around the central axis O of the friction stirring tool FT only increases, and the forward angle θ (the angle of the central axis CA with respect to the normal N at each point of the outer peripheral surface S2) and the friction stirring tool Other parameters such as the position of the central axis CA of the FT in the extension direction are not changed. In this case, the stirring depth D (distance from the outer peripheral surfaces S1 and S2 to the tip _DP of the probe portion PR) is maintained at the optimum value D0. However, as shown in FIG. 23, when the friction stir tool FT starts to rotate around the central axis O, the friction stir welding target site WP (first friction stir welding target site WP1 or second friction stir welding target site WP2). The penetration depth d of the shoulder portion (tip of the shank portion SH) inward becomes smaller than the optimum value d ₀ . Therefore, as shown in FIG. 24, the plastically fluidized metal material may float, the outer peripheral surface S2 may bulge, and a bonding defect (cavity) may occur inside the second friction stir welding target portion WP2. In FIG. 24, the trail of the rear end of the shoulder portion of the friction stirring tool FT is shown by a two-dot chain line.

The present invention has been made to address the above problems, and an object of the present invention is to provide a friction stir welding method capable of suppressing the occurrence of bonding defects. In the following description of each component of the present invention, in order to facilitate understanding of the present invention, the reference numerals of the corresponding parts of the embodiments are described in parentheses, but each component of the present invention is described. It should not be construed as limited to the configuration of the corresponding parts indicated by the reference numerals of the embodiments.

In order to achieve the above object, the feature of the present invention is a first friction stir welding target portion (WP1) and a second friction stir welding target composed of portions located on both sides of the butt surface of the two members (10, 20). A portion (WP2), a first friction stir welding target portion having a flat outer peripheral surface (S1) extending in a predetermined direction, and an end portion of the outer peripheral surface of the first friction stir welding target portion in an extending direction. The friction stir welding tool (FT) is scanned along the second friction stir welding target portion having a curved outer peripheral surface (S2) extending from the first friction stir welding target portion and the second friction stir welding target portion. This is a friction stir welding method in which the parts to be joined by friction stir welding are continuously joined in this order, and the latter half of the shoulder portion of the friction stir tool in the scanning direction is inside the first portion to be welded by friction stir welding as compared with the first half. The advance angle of the friction stir tool at the first friction stir welding target site is set to a predetermined value so that it penetrates deeply into the first friction stir welding target, and the depth of penetration of the shoulder portion into the first friction stir welding target and the second friction stir welding target. The depth of penetration of the shoulder portion into the site is the same, and the depth of penetration of the tip of the friction stir tool into the site of the first friction stir welding target and the depth of penetration of the second friction stir welding target site. The tip of the friction stir tool is placed at the boundary between the first friction stir welding target portion and the second friction stir welding target portion so that the stirring depth, which is the penetration depth of the tip portion into the inside, is the same. When it reaches the point, the friction stir welding tool is started to rotate around the central axis of the outer peripheral surface of the second friction stir welding target portion, and the advance angle is gradually changed , which is the friction stir welding method.

According to the present invention, the depth of penetration of the shoulder portion of the friction stir tool is optimized from the first friction stir welding target portion having a flat outer peripheral surface to the second friction stir welding target portion having a curved outer peripheral surface. Can be kept at a value. Therefore, the occurrence of joint defects as shown in FIG. 24 can be suppressed.

It is a perspective view of the 1st member and 2nd member which are joined by using the friction stir welding method which concerns on 1st to 3rd Embodiment of this invention. It is a perspective view which shows the outline of the joining process of the friction stir welding method of this invention. FIG. 3 is a cross-sectional view showing a state in which a friction stir tool is scanned along a first friction stir welding target portion at a boundary surface between a first member and a second member according to the first to third embodiments of the present invention. be. It is sectional drawing which shows the state which reached the boundary part of the 1st friction stir welding target part and the 2nd friction stir welding target part of a friction stir welding tool. It is sectional drawing which shows the posture of the friction agitation tool when the friction agitation tool is slightly rotated along the 2nd friction stir welding target part without changing the advance angle. It is sectional drawing which shows a mode that the friction stir tool is rotated along the 2nd friction stir welding target part while gradually increasing the advance angle. FIG. 5 is a cross-sectional view showing a state in which the rear end of the shoulder portion in the scanning direction reaches the boundary portion between the first friction stir welding target portion and the second friction stir welding target portion. It is sectional drawing which shows the mode that the friction stir tool is rotated along the part to be joined by the 2nd friction stir welding without changing the advance angle. It is sectional drawing which shows the state which the tip of the probe part reached the boundary part of the 1st friction stir welding target part and the 2nd friction stir welding target part. It is sectional drawing which shows the posture of the friction stir tool when the friction stir tool is slightly translated along the third friction stir welding target part without changing the advance angle. It is sectional drawing which shows a mode that the friction stir tool is translated along the third friction stir welding target part while gradually increasing the advance angle. FIG. 5 is a cross-sectional view showing a state in which the rear end of the shoulder portion in the scanning direction reaches the boundary portion between the second friction stir welding target portion and the third friction stir welding target portion. It is sectional drawing which shows a mode that the friction stir tool is translated along the third friction stir welding target part. FIG. 5 is a cross-sectional view showing a state in which the rear end of the shoulder portion in the scanning direction reaches the boundary portion between the first friction stir welding target portion and the second friction stir welding target portion according to the second embodiment of the present invention. It is sectional drawing which shows the mode that the friction stir tool is rotated along the 2nd friction stir welding target part. According to the third embodiment of the present invention, the posture of the friction agitation tool when the friction agitation tool is slightly rotated along the second friction stir welding target portion without changing the pushing amount of the friction agitation tool is shown. It is a cross-sectional view. It is sectional drawing which shows a mode that the friction stir tool is rotated along the 2nd friction stir welding target part while gradually increasing the pushing amount. It is sectional drawing which shows the mode that the friction stir tool is rotated along the part to be joined by the 2nd friction stir welding without changing the pushing amount. It is sectional drawing which shows the posture of the friction stir tool when the friction stir tool is translated along the third friction stir welding target part without changing the pushing amount. FIG. 5 is a cross-sectional view showing a state in which the rear end of the shoulder portion in the scanning direction reaches the boundary portion between the second friction stir welding target portion and the third friction stir welding target portion. It is sectional drawing which shows a mode that the friction stir tool is translated along the third friction stir welding target part without changing the pushing amount. It is a perspective view which shows the outline of the joining process of the conventional friction stir welding method. In relation to the conventional friction stir welding method, a state in which the friction stir tool is scanned along the first friction stir welding target portion and the second friction stir welding target portion on the abutting surface between the first member and the second member. It is sectional drawing which shows. It is sectional drawing which shows the joint defect.

(First Embodiment)
Hereinafter, using the friction stir welding method according to the first embodiment of the present invention, the first member 10 and the second member 20 shown in FIG. 1 are joined to form a box shape (case shape) opened in one direction. The procedure for manufacturing the product (butting process and joining process) will be described. The first member 10 and the second member 20 are made of an aluminum alloy. The first member 10 has a side wall portion 11 and a peripheral wall portion 12. The side wall portion 11 is a substantially rectangular plate-shaped portion. That is, the side wall portion 111 has long side portions 111, 113 and short side portions 112, 114 that face each other. The intersection (corner portion C1a) between the long side portion 111 and the short side portion 112 of the side wall portion 11 is curved in an arc shape. Further, the intersection (corner portion C1b) between the long side portion 113 and the short side portion 112 of the side wall portion 11 is curved in an arc shape.

The peripheral wall portion 12 extends perpendicularly to the surface of the side wall portion 11 from the peripheral edge portion of the side wall portion 11 and extends along the peripheral edge portion of the side wall portion 11. The peripheral wall portion 12 is formed along a portion of the peripheral edge portion of the side wall portion 11 excluding the short side portion 114. Specifically, the peripheral wall portion 12 includes a first wall portion 121 along the long side portion 111, a second wall portion 122 along the corner portion C1a, a third wall portion 123 along the short side portion 112, and a corner portion. It has a fourth wall portion 124 along C1b and a fifth wall portion 125 along the long side portion 113. The outer peripheral surfaces of the first wall portion 121, the third wall portion 123, and the fifth wall portion 125 are flat. Further, the outer peripheral surfaces of the second wall portion 122 and the fourth wall portion 124 are arc surfaces. The widths of the first wall portion 121 to the fifth wall portion 125 (dimensions in the direction parallel to the wall thickness direction of the side wall portion 11) are the same. Further, the wall thicknesses of the first wall portion 121 to the fifth wall portion 125 are the same. Further, the end surface E1 of the first wall portion 121 to the fifth wall portion 125 in the width direction, which is opposite to the side wall portion 11, is parallel to the surface of the side wall portion 11.

The second member 20 has a plane-symmetrical shape with respect to the end surface of the peripheral wall portion 12 of the first member 10. That is, the second member 20 has a side wall portion 21 similar to the side wall portion 11 and a peripheral wall portion 22 similar to the peripheral wall portion 12. The side wall portion 21 has long side portions 211,213 and short side portions 212,214. The intersection (corner portion C2a) between the long side portion 211 and the short side portion 212 of the side wall portion 21 is curved in an arc shape. Further, the intersection (corner portion C2b) between the long side portion 213 and the short side portion 212 of the side wall portion 21 is curved in an arc shape. The peripheral wall portion 22 has a first wall portion 221 to a fifth wall portion 225 similar to the first wall portion 121 to the fifth wall portion 125. The end face E2 of the first wall portion 221 to the fifth wall portion 225 in the width direction, which is opposite to the side wall portion 21, is parallel to the surface of the side wall portion 21.

As will be described below, the peripheral wall portion 12 of the first member 10 and the peripheral wall portion 22 of the second member 20 are abutted against each other, and friction stir welding is performed along the friction stir welding target portion WP consisting of portions located on both sides of the abutting surface. The tool FT is scanned to join the first member 10 and the second member 20 (see FIG. 2). The friction stir tool FT is attached to the drive device DR. The drive device DR includes a control device (not shown) and various actuators. The control device controls various parameters related to the position and orientation of the friction stir tool FT and the number of rotations around the central axis CA according to a predetermined computer program. In addition, the various actuators operate according to the parameters to change the rotation speed, position, and posture of the friction stir tool FT.

(Matching process)
Next, the matching process will be described. The end face E1 of the peripheral wall portion 12 of the first member 10 and the end face E2 of the peripheral wall portion 22 of the second member 20 are butted against each other. The first member 10 and the second member 20 are arranged so that a step is not formed at the boundary between the peripheral wall portion 12 and the peripheral wall portion 22. That is, both members are arranged so that the outer peripheral surface of the peripheral wall portion 12 of the first member 10 and the outer peripheral surface of the peripheral wall portion 22 of the second member 20 are continuous. In the following description, of the friction stir welding target portion WP between the first member 10 and the second member 20, the portion where the first wall portion 121 and the first wall portion 221 are joined is the first friction stir welding target portion. Called WP1. The portion where the second wall portion 122 and the second wall portion 222 are joined is referred to as a second friction stir welding target portion WP2. The portion where the third wall portion 123 and the third wall portion 223 are joined is referred to as a third friction stir welding target portion WP3. The portion where the fourth wall portion 124 and the fourth wall portion 224 are joined is referred to as a fourth friction stir welding target portion WP4. Further, the portion where the fifth wall portion 125 and the fifth wall portion 225 are joined is referred to as a fifth friction stir welding target portion WP5.

The first member 10 and the second member 20 butted as described above are attached to and fixed to a support device (not shown). In the following description, the extending direction of the outer peripheral surface S1 of the first friction stir welding target portion WP1 is referred to as a front-rear direction, and the alignment direction of the first member 10 and the second member 20 is referred to as a left-right direction. Further, the normal direction of the outer peripheral surface S1 of the first friction stir welding target portion WP1 is referred to as a vertical direction.

(Joining process)
Next, the joining process will be described. In this step, the first friction stir welding target portion WP1 is joined, the second friction stir welding target portion WP2 is joined, and the third friction stir welding target portion WP3 is joined in this order. Then, the joining of the fourth joining target site WP4 and the joining of the fifth joining target site WP5 are subsequently carried out in this order. The above steps are carried out continuously. What is a series of steps from the joining of the first friction stirring joining target part WP1 to the joining of the third joining target part WP3 and the series of steps from the joining of the third joining target part WP3 to the joining of the fifth joining target part WP5? It is almost the same. Therefore, a series of steps from the joining of the first friction stirring joining target site WP1 to the joining of the third joining target site WP3 will be described below, and from the joining of the third joining target site WP3 to the joining of the fifth joining target site WP5. The description of a series of steps over the process will be omitted. In addition, in FIGS. 3 to 20, the tip (probe portion PR) of the friction stir tool FT is actually a conical trapezoid, but in the following description, the tip DP of the probe portion PR is sharpened. Further, the broken line La represents a position where the distance from the outer peripheral surfaces S1, S2, S3 is the optimum value _d0 of the depth d. Further, the broken line Lb represents a position where the distance from the outer peripheral surfaces S1, S2, S3 is the optimum value D ₀ of the stirring depth D.

First, as shown in FIG. 2, the friction stir tool FT is arranged above the first member 10 and the second member 20. Next, the position of the central axis CA of the friction stir tool FT in the left-right direction and the position of the abutting surface (that is, the end face E1 and the end face E2) of the first member 10 and the second member 20 in the left-right direction coincide with each other. The positions of the first member 10 and the second member 20 and the friction stir tool FT in the left-right direction are set. Further, the tip of the friction stir tool FT is located above the end of the first friction stir welding target portion WP1 in the front-rear direction and on the opposite side of the second friction stir welding target portion WP2. , The position of the friction stir tool FT is set.

Next, the friction stir tool FT is lowered while being rotated around the central axis CA, and the tip end portion of the friction stir tool FT is press-fitted into the boundary portion between the first wall portion 121 and the first wall portion 221. As shown in FIG. 3, the advance angle θ is set to, for example, 3 °. As a result, the latter half of the shoulder portion of the friction stir tool FT (rear side portion in the scanning direction of the friction stir tool FT) is compared with the first half portion (front side portion in the scanning direction of the friction stir tool FT). It penetrates deeply into the joint target site WP1. Specifically, the depth d of the shoulder portion into the first friction stir welding target portion WP1 is set to an optimum value d ₀ (for example, 0.3 mm) capable of suppressing the lifting of the plastically fluidized metal material. .. The front end of the shoulder portion is located slightly above the outer peripheral surface S1.

Next, the friction stirring tool FT is scanned (translated) forward (to the right in FIG. 3). Of the parameters related to the position and posture of the friction stir tool FT, the parameters other than the parameters related to the position in the front-rear direction are not changed. According to this, the tip DP of the probe portion PR moves along the broken line Lb. That is, the stirring depth D is maintained at the optimum value D ₀ . Further, the rear end RP of the shoulder portion in the scanning direction (that is, the portion that penetrates deepest into the friction stir welding target portion WP) moves along the broken line La in FIG. That is, the penetration depth d is maintained at the optimum value d ₀ . As shown in FIG. 4, when the tip DP of the probe portion PR of the friction stir tool FT reaches the boundary portion BD ₁₂ between the first friction stir welding target portion WP1 and the second friction stir welding target portion WP2, friction stirring The forward scanning of the tool FT is stopped.

Next, the friction stir tool FT begins to be scanned (rotated) around the central axis O of the outer peripheral surface S2 of the second friction stir welding target portion WP2. At that time, the tip DP of the probe portion PR of the friction stir tool FT moves along the broken line Lb in FIG. 4, and the rear end RP of the shoulder portion in the scanning direction moves along the broken line La in FIG. Various parameters related to the position and orientation of the friction stir tool FT are changed. That is, the stirring depth D (distance from the outer peripheral surface S2 to the tip DP of the probe portion PR) is maintained at the optimum value D ₀ , and the penetration depth d of the shoulder portion of the friction stir tool FT is the optimum value d ₀ ( For example, various parameters are changed so as to be held at 0.3 mm).

From the state of FIG. 4, the tip DP of the probe portion PR moves along the broken line Lb in FIG. 5 by increasing the rotation angle α around the central axis O of the friction stirring tool FT. That is, the stirring depth D is maintained at the optimum value D ₀ . Here, as shown in FIG. 5, when the rotation angle α around the central axis O of the friction stir tool FT starts to increase, the rotation angle among the parameters related to the position and orientation of the friction stir tool FT When the parameters other than α are not changed, the rear end RP of the shoulder portion in the scanning direction deviates from the broken line La in FIG. That is, the penetration depth d gradually decreases. Therefore, as shown in FIG. 6, the friction stirring tool FT moves the probe portion PR so that the penetration depth d is maintained at the optimum value d ₀ while the rotation angle α of the friction stirring tool FT is gradually increased. The advance angle θ is increased by gradually rotating around the tip DP of. When the rear end RP in the scanning direction of the shoulder portion reaches the boundary portion BD ₁₂ (see FIG. 7), the rotation of the friction stirring tool FT around the tip DP (change of the advance angle θ) is stopped.

Next, as shown in FIG. 8, the friction stirring tool FT is further rotated around the central axis O. Of the parameters related to the position and posture of the friction stir tool FT, the parameters other than the rotation angle α are not changed. That is, the advance angle θ at the time point shown in FIG. 7 is maintained. According to this, the rear end RP of the shoulder portion in the scanning direction moves along the broken line La in FIGS. 8 and 9. That is, the penetration depth d is maintained at the optimum value d ₀ . Further, the tip DP of the probe portion PR moves along the broken line Lb in FIGS. 8 and 9. That is, the stirring depth D is maintained at the optimum value D ₀ . When the rotation angle α reaches “90 °” (that is, when the tip DP of the probe portion PR reaches the boundary portion BD ₂₃ (see FIG. 9)), the rotation of the friction stirring tool FT around the central axis O The movement is stopped.

Next, the friction stirring tool FT begins to be scanned (translated) downward. According to this, the tip DP of the probe portion PR moves along the broken line Lb in FIGS. 11 and 12. That is, the stirring depth D is maintained at the optimum value D ₀ . Here, as shown in FIG. 10, when the friction stir tool FT starts scanning downward, the parameters related to the position and posture of the friction stir tool FT, except for the parameter related to the vertical position, are not changed. In this case, the rear end RP of the shoulder portion in the scanning direction deviates from the broken line La in FIG. That is, the penetration depth d gradually increases. Therefore, as shown in FIG. 11, the friction stirring tool FT moves the tip DP of the probe portion PR so that the penetration depth d is maintained at the optimum value d ₀ while the friction stirring tool FT is translated downward. It is gradually rotated around the center, and the advance angle θ is reduced. When the rear end RP in the scanning direction of the shoulder portion reaches the boundary portion BD ₂₃ (see FIG. 12), the rotation of the friction stirring tool FT around the tip DP (change of the advance angle θ) is stopped.

Next, as shown in FIG. 13, the friction stirring tool FT is further scanned (translated) downward. Of the parameters related to the position and posture of the friction stir tool FT, the parameters other than the parameters related to the vertical position are not changed. According to this, the tip DP of the probe portion PR moves along the broken line Lb in FIG. That is, the stirring depth D is maintained at the optimum value D ₀ . Further, the rear end RP of the shoulder portion in the scanning direction moves along the broken line La in FIG. That is, the penetration depth d is maintained at the optimum value d ₀ . As described above, the first friction stir welding target portion WP1 to the third friction stir welding target portion WP3 are joined.

As described above, in the present embodiment, the position of the friction stir tool FT in the front-rear direction, the position in the up-down direction, and the rotation angle α are controlled so that the tip DP of the probe portion PR moves along the broken line Lb. To. Moreover, the advance angle θ is appropriately changed so that the rear end RP of the shoulder portion in the scanning direction moves along the broken line La. That is, according to the present embodiment, by keeping the stirring depth D at the optimum value D ₀ , the joining strength of each part is made uniform, and by keeping the penetration depth d at the optimum value d ₀ , the joining defect Can be suppressed.

(Second Embodiment)
Next, a procedure for manufacturing a product similar to that of the first embodiment will be described using the friction stir welding method according to the second embodiment of the present invention.

(Matching process)
In this embodiment as well, the first member 10 and the second member 20 are butted against each other as in the first embodiment. Since the specific procedure of this matching step is the same as that of the first embodiment, the description thereof will be omitted.

(Joining process)
Similar to the first embodiment, the first friction stir welding target portion WP1 to the fifth friction stir welding target portion WP5 are continuously joined in this order. A series of steps from the joining of the first friction stir welding target site WP1 to the joining of the third friction stir welding target site WP3, and from the joining of the third friction stir welding target site WP3 to the joining of the fifth friction stir welding target site WP5. It is almost the same as the series of steps. Therefore, a series of steps from the joining of the first friction stir welding target site WP1 to the joining of the third friction stir welding target site WP3 will be described below, and the joining of the third friction stir welding target site WP3 to the fifth friction stir welding will be described. The description of a series of steps including the joining of the target portion WP5 will be omitted.

First, the position and orientation of the friction stir tool FT with respect to the first member 10 and the second member 20 are set in the same manner as at the start of joining in the first embodiment.

Next, as in the first embodiment, the friction stir tool FT is lowered while being rotated around the central axis CA, and the tip end portion of the friction stir welding tool FT is press-fitted into the rear end portion of the first friction stir welding target portion WP1. (See FIG. 3). The advance angle θ is set to, for example, 3 °. As a result, the penetration depth d of the shoulder portion into the first friction stir welding target portion WP1 is set to the optimum value d ₀ (for example, 0.3 mm).

Next, the friction stirring tool FT is scanned (translated) forward (to the right in FIG. 3). Of the parameters related to the position and posture of the friction stir tool FT, the parameters other than the parameters related to the position in the front-rear direction are not changed. According to this, the rear end RP of the shoulder portion in the scanning direction moves along the broken line La in FIG. That is, the penetration depth d is maintained at the optimum value d ₀ . Further, the tip DP of the probe portion PR moves along the broken line Lb. That is, the stirring depth D is maintained at the optimum value D ₀ .

In the second embodiment, unlike the first embodiment, the forward movement of the friction stir tool FT is not stopped even if the tip DP of the probe portion PR of the friction stir tool FT reaches the boundary portion BD ₁₂ . In the second embodiment, as shown in FIG. 14, the rear end RP of the friction stir welding tool FT in the scanning direction is the boundary portion between the first friction stir welding target portion WP1 and the second friction stir welding target portion WP2. When the BD ₁₂ is reached, the forward movement of the friction stir tool FT is stopped. According to this, as shown in FIG. 14, the tip DP of the probe portion PR moves forward when the tip DP of the probe portion PR passes through the boundary portion BD ₁₂ and deviates from the broken line Lb. That is, when the tip DP of the probe portion PR passes through the boundary portion BD ₁₂ , the stirring depth D becomes shallower than the optimum value D ₀ .

Next, as shown in FIG. 15, the friction stir tool FT is scanned (rotated) around the central axis O of the outer peripheral surface S2. Of the parameters related to the position and posture of the friction stir tool FT, the parameters other than the rotation angle α around the central axis O are not changed. According to this, the rear end RP of the shoulder portion in the scanning direction moves along the broken line La in FIG. That is, the penetration depth d is maintained at the optimum value d ₀ . On the other hand, the tip DP of the probe portion PR deviates from the broken line Lb in FIG. 15 and moves. That is, the stirring depth D is shallower than the optimum value D ₀ . When the rotation angle α of the friction stir tool FT around the central axis O reaches “90 °”, the rear end RP of the shoulder portion in the scanning direction becomes the second friction stir welding target portion WP2 and the third friction stir welding target portion. It reaches the boundary portion BD ₂₃ with WP3. Further, the tip DP of the probe portion PR crosses the broken line Lb after entering the third friction stir welding target portion WP3 beyond the boundary portion BD ₂₃ . At this point, the rotation of the friction stir tool FT around the central axis O is stopped.

Next, the friction stir tool FT is scanned (translated) downward. Of the parameters related to the position and posture of the friction stir tool FT, the parameters other than the parameters related to the vertical position are not changed. According to this, the rear end RP of the shoulder portion in the scanning direction moves along the broken line La in FIG. That is, the penetration depth d is maintained at the optimum value d ₀ . Further, the tip DP of the probe portion PR moves along the broken line Lb in FIG. That is, the stirring depth D is maintained at the optimum value D ₀ . As described above, the first friction stir welding target portion WP1 to the third friction stir welding target portion WP3 are joined.

As described above, in the present embodiment, the position in the front-rear direction, the position in the vertical direction, and the rotation angle α of the friction stir tool FT so that the rear end RP in the scanning direction of the shoulder portion moves along the broken line La. Is controlled. That is, the penetration depth d is maintained at the optimum value d ₀ . Therefore, the occurrence of joint defects can be suppressed. In this embodiment, only the position of the friction stirring tool FT in the front-rear direction, the position in the up-down direction, and the rotation angle α are controlled. That is, unlike the first embodiment, for example, the advance angle θ is not controlled. Therefore, the configuration of the computer program for controlling the friction stir tool FT and various actuators can be simplified.

(Third Embodiment)
Next, a procedure for manufacturing a product similar to that of the first embodiment will be described using the friction stir welding method according to the third embodiment of the present invention.

(Matching process)
In this embodiment as well, the first member 10 and the second member 20 are butted against each other as in the first embodiment. Since the specific procedure of this matching step is the same as that of the first embodiment, the description thereof will be omitted.

(Joining process)
Similar to the first embodiment, the first friction stir welding target portion WP1 to the fifth friction stir welding target portion WP5 are continuously joined in this order. A series of steps from the joining of the first friction stir welding target site WP1 to the joining of the third friction stir welding target site WP3, and from the joining of the third friction stir welding target site WP3 to the joining of the fifth friction stir welding target site WP5. It is almost the same as the series of steps. Therefore, a series of steps from the joining of the first friction stir welding target site WP1 to the joining of the third friction stir welding target site WP3 will be described below, and the joining of the third friction stir welding target site WP3 to the fifth friction stir welding will be described. The description of a series of steps including the joining of the target portion WP5 will be omitted.

First, the position and orientation of the friction stir tool FT with respect to the first member 10 and the second member 20 are set in the same manner as at the start of joining in the first embodiment.

Next, as in the first embodiment, the friction stir tool FT is lowered while being rotated around the central axis CA, and the tip end portion of the friction stir welding tool FT is press-fitted into the rear end portion of the first friction stir welding target portion WP1. (See FIG. 3). The advance angle θ is set to, for example, 3 °. As a result, the penetration depth d is set to the optimum value d ₀ (for example, 0.3 mm).

Next, the friction stirring tool FT is scanned (translated) forward (to the right in FIG. 3). Of the parameters related to the position and posture of the friction stir tool FT, the parameters other than the parameters related to the position in the front-rear direction are not changed. According to this, the rear end RP of the shoulder portion in the scanning direction moves along the broken line La in FIG. That is, the penetration depth d is maintained at the optimum value d ₀ . Further, the tip DP of the probe portion PR moves along the broken line Lb. That is, the stirring depth D is maintained at the optimum value D ₀ . As shown in FIG. 4, when the tip DP of the probe portion PR of the friction stir tool FT reaches the boundary portion BD ₁₂ between the first friction stir welding target portion WP1 and the second friction stir welding target portion WP2, friction stirring The forward scanning of the tool FT is stopped.

Next, the friction stir tool FT begins to be scanned (rotated) around the central axis O of the outer peripheral surface S2 of the second friction stir welding target portion WP2. At that time, various parameters related to the position and orientation of the friction stir tool FT are changed so that the rear end RP in the scanning direction of the shoulder portion of the friction stir tool FT moves along the broken line La in FIG. That is, various parameters are changed so that the penetration depth d of the shoulder portion of the friction stir tool FT is maintained at the optimum value d ₀ (for example, 0.3 mm).

Assuming that, as shown in FIG. 16, when the rotation angle α around the central axis O of the friction stir tool FT begins to increase, the rotation angle α is excluded from the parameters related to the position and orientation of the friction stir tool FT. If the parameters are not changed, the rear end RP of the shoulder portion in the scanning direction deviates from the broken line La in FIG. That is, the penetration depth d gradually decreases. Therefore, as shown in FIG. 17, the friction stir tool FT is set to the central axis CA so that the penetration depth d is maintained at the optimum value d ₀ while the rotation angle α of the friction stir tool FT is gradually increased. The amount of the friction stir tool FT pushed into the friction stir welding target portion WP is gradually increased. According to this, the tip DP of the probe portion PR deviates slightly from the broken line Lb in FIG. That is, the stirring depth D becomes slightly deeper than the optimum value D ₀ . When the rear end RP in the scanning direction of the shoulder portion reaches the boundary portion BD ₁₂ (see FIG. 18), the movement of the friction stirring tool FT in the extension direction of the central axis CA (change in the pushing amount) is stopped.

Next, the friction stirring tool FT is further rotated around the central axis O. Of the parameters related to the position and posture of the friction stir tool FT, the parameters other than the rotation angle α are not changed. That is, the pushing amount at the time shown in FIG. 17 is maintained. According to this, the rear end RP of the shoulder portion in the scanning direction moves along the broken line La in FIG. That is, the penetration depth d is maintained at the optimum value d ₀ . On the other hand, the tip DP of the probe portion PR deviates slightly from the broken line Lb in FIG. That is, the stirring depth D is slightly deeper than the optimum value D ₀ . When the rotation angle α reaches “90 °” (that is, when the tip DP of the probe portion PR reaches the boundary portion BD ₂₃ ), the rotation of the friction stirring tool FT around the central axis O is stopped. ..

Next, the friction stirring tool FT begins to be scanned (translated) downward. If, as shown in FIG. 19, when the friction stir tool FT starts to be scanned downward, the parameters related to the position and posture of the friction stir tool FT, excluding the parameters related to the vertical position, are not changed. , The penetration depth d gradually increases. Therefore, as shown in FIG. 20, the friction stirring tool FT is moved in the extending direction of the central axis CA so that the penetration depth d is maintained at the optimum value d ₀ while the friction stirring tool FT is translated downward. It is moved and the amount of pushing is gradually reduced. The tip DP of the probe portion PR moves slightly deviating from the broken line Lb in FIG. 20. That is, the stirring depth D is slightly deeper than the optimum value D ₀ . When the rear end RP of the shoulder portion in the scanning direction reaches the boundary portion BD ₂₃ (see FIG. 21), the tip DP of the probe portion PR intersects the broken line Lb in FIG. 20. At this point, the movement (change of the pushing amount) of the friction stirring tool FT in the extending direction of the central axis CA is stopped.

Next, the friction stirring tool FT is further scanned (translated) downward. Of the parameters related to the position and posture of the friction stir tool FT, the parameters other than the parameters related to the vertical position are not changed. According to this, the rear end RP of the shoulder portion in the scanning direction moves along the broken line La in FIG. 121. That is, the penetration depth d is maintained at the optimum value d ₀ . Further, the tip DP of the probe portion PR moves along the broken line Lb in FIG. 21. That is, the stirring depth D is maintained at the optimum value D ₀ . As described above, the first friction stir welding target portion WP1 to the third friction stir welding target portion WP3 are joined.

As described above, in the present embodiment, the position of the friction stirring tool FT in the front-rear direction, the position in the up-down direction, the rotation angle α, and so as to move the rear end RP of the shoulder portion in the scanning direction along the broken line La. The amount of pushing is controlled. That is, the penetration depth d is maintained at the optimum value d ₀ . Therefore, the occurrence of joint defects can be suppressed. Further, in the present embodiment, in the curved portion (second friction stir welding target portion WP2 and fourth friction stir welding target portion WP4), the pushing amount of the friction stir tool FT is a linear portion (first friction stir welding target portion WP1, It is slightly increased as compared with the third friction stir welding target portion WP3 and the fifth friction stir welding target portion WP5). That is, the stirring depth D of the curved portion (that is, the depth of the joined portion) is slightly larger than the stirring depth D of the straight portion. Therefore, the joint strength of the curved portion can be set higher than the joint strength of the straight portion.

Furthermore, the practice of the present invention is not limited to the above-described embodiment, and various changes can be made as long as the object of the present invention is not deviated.

In the above embodiment, the first member 10 and the second member 20 are fixed, and the friction stir welding tool FT is moved with respect to the first member 10 and the second member 20. Instead of this, the friction stir tool FT is fixed so that the relative positions and orientations of the first member 10 and the second member 20 and the friction stir tool FT are the same as those in the above embodiment, and friction is performed. The first member 10 and the second member 20 may be moved with respect to the stirring tool FT. Further, the friction stir tool FT is moved so that the relative position and orientation with respect to the friction stir tool FT are the same as those in the above embodiment, and the first member 10 and the second member are relative to the friction stir tool FT. 20 may be moved.

10 ... 1st member, 20 ... 2nd member, 11 ... Side wall, 12 ... Peripheral wall BD ₁₂ ... Boundary, BD ₂₃ ... Boundary, CA ... Center Shaft, DP ... Tip, DR ... Drive, FT ... Friction stir tool, N ... Normal, O ... Central axis, PR ... Probe, RP ... Rear end , S1, S2, S3 ... Outer surface, WP ... Friction stir welding target site, WP1 ... First friction stir welding target site, WP2 ... Second friction stir welding target site, WP3 ... Third friction stir welding target part, WP4 ... Fourth friction stir welding target part, WP5 ... Fifth friction stir welding target part, α ... Rotation angle, θ ... Advance angle

Claims (1)

A first friction stir welding target part and a second friction stir welding target part composed of parts located on both sides of the butt surface of the two members, and having a flat outer peripheral surface extending in a predetermined direction. A friction stir tool is provided along the target portion and the second friction stir welding target portion having a curved outer peripheral surface extending in the predetermined direction from the end portion of the outer peripheral surface of the first friction stir welding target portion in the extending direction. A friction stir welding method in which the first friction stir welding target portion and the second friction stir welding target portion are continuously joined in this order by scanning.
The forward angle of the friction stir tool at the first friction stir welding target portion so that the latter half of the shoulder portion of the friction stir tool in the scanning direction penetrates deeper into the first friction stir welding target portion than the first half portion. To the specified value,
The depth of penetration of the shoulder portion into the first friction stir welding target portion and the penetration depth of the shoulder portion into the second friction stir welding target portion are the same, and
The stirring depth, which is the depth of penetration of the tip of the friction stir tool into the first friction stir welding target portion, and the stirring depth, which is the penetration depth of the tip into the second friction stir welding target portion. So that it is the same as
When the tip of the friction stir tool reaches the boundary between the first friction stir welding target portion and the second friction stir welding target portion, the friction stir tool is used on the second friction stir welding target portion. A friction stir welding method in which the advance angle is gradually changed while starting to rotate around the central axis of the outer peripheral surface .

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