JP2002210570A - Friction stirring joining method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent entrapment of remaining air into a joined part and to form the sound joined part when a friction stirring joining is applied to a long member by connecting with a plurality of joining parts. SOLUTION: A pin 1 is inserted into butting parts of two materials W1, W2 to be joined mutually butting the side surfaces and the friction stirring joining is applied to the materials, W1, W2 to be joined by shifting along the butting line WL between the materials W1, W2 to be joined while rotating the pin 1, and on the way of the butting line WL, the pin 1 under shifting, is raised up at the raising-up angle θ at larger than the angle α between the tip part of the pin 1 in a rotating tool and the outer periphery of a shoulder from the butting part. Successively, the pin 1 is again inserted into a joined part WB at already joined part side from the raising-up starting position (end point P1E in the preceding friction stirring joining process) of the pin 1, and shifted to non-joining part side of the butting line WL while rotating the pin 1. Further, a void V generated at a trace by drawing out the pin 1, is formed as a releasing shape toward the downstream side in the joining direction D and the air is exhausted into the downstream side from the void V during joining.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a friction stir welding method suitable for joining long structural members such as automobiles, railway vehicles, and buildings.

[0002]

2. Description of the Related Art A friction stir welding method has attracted attention as a solid-state welding method in which thermal distortion generated during welding is small and good shape accuracy is maintained after welding. In the friction stir welding method, as shown in FIG. 1, a rotor 2 having a coaxial pin 1 attached to the tip is used. The pin 1 is inserted into the butted portion of the workpieces W ₁ and W ₂ while rotating, and the pin 1 is moved along the butted line WL (joining direction D). The welded material W _1, W ₂
Is heated by the frictional heat of the pin 1 and is stirred by the rotation of the pin 1. The metal that has plastically flowed by heating and stirring is mixed with each other between the workpieces W ₁ and W ₂ , and is solidified by the rapid removal of heat.
Is formed. The friction stir welding method is being applied to various members such as automobiles, railway vehicles, and building structures, taking advantage of the advantage of maintaining good shape accuracy after welding.

[0003]

In the fields of automobiles, railway vehicles, building structures, and the like, long structural members are often used. In the case of the long structural member, the joint WB is long, and the relative movement of the pin 1 along the long butting line WL is required. The relative movement of the pin 1 includes the pin 1 with respect to the workpieces W ₁ and W ₂ .
And the material W ₁ , W ₂
There is a method to move. The method of moving the workpieces W ₁ and W ₂ requires only a small-scale friction stirrer, but it is difficult to accurately move the long workpieces W ₁ and W ₂ .
When the workpieces W ₁ and W ₂ move while being displaced, the pin 1 is displaced in the height direction or the width direction with respect to the butting line WL,
Defects such as poor agitation tend to occur at the joint WB. In the method of moving the pin 1, since the welded material W _1, W ₂ are fixed butt line WL are secured in position, it is possible to bond with good accuracy. However, since the movable distance of the pin 1 is restricted by the size of the friction stirrer,
When joining long structural members having a long butt line WL, there is a disadvantage that the equipment becomes large.

[0004]

SUMMARY OF THE INVENTION The present invention has been devised in order to solve such a problem, and when joining a long material to be joined by joining a plurality of joints. The holes created in the trace of pulling out the pin in the friction stir welding process are opened to the downstream side in the welding direction to prevent air from getting into the joint and even when using small-scale equipment An object of the present invention is to precisely join a long member by friction stir welding.

According to the friction stir welding method of the present invention, in order to achieve the object, a pin is inserted into a butt portion of two materials to be welded to each other, and the butt line between the materials to be welded is rotated while rotating the pin. The workpiece is friction stir welded by moving along the same direction, and the pin which is running in the middle of the butt line is raised from the butt portion at a rising angle θ larger than the angle α between the tip of the pin of the rotating tool and the outer periphery of the shoulder. And raise
Next, the pin is inserted again into the butted portion on the already joined portion from the rising start position of the pin, and the pin is rotated and moved to the unjoined portion side of the butting line while rotating. In the subsequent friction stir welding step, a pin that is shorter than the pin used in the preceding friction stir welding step by the amount of shoulder pushing may be used, and the shoulder may be pushed into the material to be joined when joining the joint portions. By appropriately adjusting the amount of pushing of the shoulder, necessary metal is secured even in a portion thinned in the preceding friction stir welding step, and the occurrence of a hollow defect due to insufficient metal supply is prevented. The pin may be raised continuously, intermittently, swirled, or a combination thereof.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, for example, a friction stir welding apparatus whose equipment configuration is schematically shown in FIG. 2 is used. In this friction stir welding apparatus, an X-axis drive motor 13 is provided on a beam 12 extending over an upper part of a portal frame 11, and a movable gantry 14 is arranged so as to be able to travel. The movable gantry 14 can be moved up and down by a Z-axis drive motor 15 and has a main shaft motor 16. The output of the spindle motor 16 is transmitted to the rotor 2 via the belt 17. Pin 1 at the tip of rotor 2 (Fig. 1)
Are mounted coaxially, and the pin 1 is directed to a material to be joined (not shown) arranged on the table 20. Since the material to be joined is inclined such that the pin 1 is directed in the forward direction at an angle of about 3 degrees toward the joint WB,
It is placed on the gantry 19 with the inclination angle adjusted by the joining jig 18.

Material W to be joined₁, W_TwoIs its own weight or an appropriate fixed hand
At the step, it is fixed to the gantry 19 via the joining jig 18 and
Material W₁, W_TwoThe butt line WL is in the traveling direction of the moving base 14
(FIG. 3). One end position of the butting line WL (start point
P_1S) To connect the pin 1 to the workpiece W ₁, W_TwoInsert between pins
1 while rotating toward the other end of the butt line WL.
Let Workpiece W₁, W_TwoIs due to the rotational friction of pin 1.
Heated and agitated, both materials W to be joined₁, W_TwoAcross
The metal flows plastically. After Pin 1 passes, heat
Lost source and workpiece W₁, W_TwoIs cooled rapidly,
The plasticized metal solidifies and the joint WB is formed sequentially
You.

A pin that can move along the direction of the butting line WL
The movable range length ML of 1 includes the portal frame 11 and the like.
Of the friction stir welding device. So
Therefore, the long material W to be joined₁, W_TwoWhen joining, butting
The movable range length ML may be shorter than the set line WL.
(FIG. 4). Friction stir welding of such a long butt line WL
To be joined, the workpiece W₁, W_TwoStarting point P at one end of_1STo
Insert the pin 1 and insert the other end along the butt line WL
To the end point P _1EIn
1 to the material W to be joined₁, W_TwoPull out from.

Next, the material W to be welded is set so that the end point P _1E, which is an unjoined portion, and the other end are within the movable range of the pin 1.
₁ and W ₂ are moved, and the workpieces W ₁ and W ₂ are fixed on the gantry 19 via the joining jig 18 at that position. Then, a subsequent start point P _2S is set at a position slightly returned from the end point P _1E to the start point P _1S side in the preceding friction stir welding step, the pin 1 is inserted into the start point P _2S , and the workpieces W ₁ , W ₂ The pin 1 to the end point _P2E toward the other end of. In this manner, the workpieces W ₁ and W ₂ are friction stir welded over the entire length of the long butt line WL. When joining longer workpieces W ₁ and W ₂ , three or more friction stir welding processes are repeated in the same manner from the relationship between the length of the butt line WL and the movable range length ML of the pin 1.

In the preceding friction stir welding process, the end point P_1E
A hole V (FIG. 5) is formed in the trace where the pin 1 is pulled out by
ing. The holes V are formed at the beginning of the subsequent friction stir welding process.
Point P _2STo the end point P_1EStarting point P_1SSet to the side,
The joint WB formed in the subsequent friction stir welding process is
It is closed by burlap. But the leading
Direction perpendicular to the joining direction D in the friction stir welding process, that is,
Workpiece W₁, W_TwoPull out pin 1 in the direction perpendicular to the surface of
Specifically, the inside of the hole V located on the downstream side with respect to the joining direction D
The wall S is substantially perpendicular to the joining direction D. Orthogonal to joining direction D
The inner wall S is formed with a hole V in a subsequent friction stir welding process.
Makes it difficult for air to escape, and the residual air gets caught in the joint WB
It may cause you to get tired.

The entrapment of residual air is eliminated by inclining the inner wall S with respect to the joining direction D and opening the holes V downstream in the joining direction D. When the pin 1 is pulled up in the preceding friction stir welding step, the inclined inner wall S
The pin 1 is formed by raising the pin 1 continuously or intermittently while running the pin 1 or by rotating the pin 1 around the spindle motor 16 (FIG. 2), the rotor 2 and the like. For example, when the pin 1 is raised in the pull-out direction U while traveling in the bonding direction D, the motion components in the bonding direction D and the pull-out direction U are combined, and the lower end of the pin 1 along the inclined line I at the predetermined rising angle θ. Moves diagonally upward (Fig. 6
a). Therefore, the void V formed at the position of the end point P _1E
The wall surface on the downstream side with respect to the joining direction D is an inclined surface VI following the movement locus of the lower end of the pin 1. The hole V is opened toward the downstream side in the joining direction D by the inclined surface VI.
The distance from the start point P _1S to the end point P _1E is set to an appropriate value within the range of the movable range length ML of the pin 1.

In the subsequent friction stir welding step, the starting point P _2S is set at a position on the starting point P _1S side from the end point P _1E, and the starting point P _2S
The pin 1 is inserted into the joint WB (FIG. 6B). The inserted pin 1 travels in the joining direction D while rotating as in the preceding friction stir welding step. At this time, since the holes V are open on the downstream side in the joining direction D, air can easily escape from the holes V. Therefore, entrainment of residual air is prevented in the process of forming the joint WB in the joining direction D due to the rotational friction of the pin 1, and the joint WB in the subsequent friction stir welding process overlaps the preceding joint WB. (FIG. 6c). In this way, a healthy joint WB free from hollow defects and entrainment of residual air is formed over the entire length of the butt line WL. At this time, in order to smoothly discharge air from the holes V, the pin 1 of the rotating tool is used.
Angle θ greater than the angle α between the tip of the
To increase. When the rising angle θ is smaller than the angle α between the tip of the pin 1 of the rotating tool and the outer periphery of the shoulder, it is difficult for the rotating tool to fall out of the hole V due to interference by the lower surface of the shoulder, and the residual air is easily caught in the joint. .

When the running pin 1 is continuously raised,
An inclined surface VI having a constant rising angle θ is formed.
a). When the pin 1 is raised intermittently, a step-like inclined surface VI is formed (FIG. 7B). When the pin 1 is turned around the spindle motor 16 (FIG. 2), the rotor 2 and the like, an inclined surface VI curved in an arc shape is formed (FIG. 7).
c). Regardless of the inclined surface VI, the holes V are open downstream in the joining direction D, so that the air in the holes V is removed in the process of forming the joining portions WB in the joining direction D. A joint portion WB that is smoothly discharged and has no entrainment of residual air is formed.

In the friction stir welding, the metal located in the front in the traveling direction is supplied rearward by the stirring force of the pin 1 so as to fill the trace of the passage of the pin 1. At this time, if the amount of metal supply to the rear is small, a hollow defect occurs at the joint WB. If friction stir welding the extruded material or the like, since there is a generation of a gap in the abutting surface and matching the welded material W _1, W ₂ to each other (bonding surface), to be joined to shoulder of the rotary tool material W _1, pushing slightly in W _2, thereby preventing the occurrence of void defects by filling the gap between the bonding surfaces by pushing it in the minute metal. For pushing the welded material W ₁ in the friction stir welding process of the prior, W slightly shoulder in ₂ (about 0.1~0.4mm specifically), by pushing amount of the shoulder material to be joined W _1, W ₂ Becomes thinner. When the subsequent friction stir welding step is performed in this state, it is necessary to slightly push the shoulder in the subsequent friction stir welding step. However, if the pin 1 used in the preceding friction stir welding process is used as it is,
_1, no longer forced to shoulder to avoid interference between the tip of the joining jig 18 and the pin 1 is located on the rear surface of the W _2. Even if the shoulder is pushed in, a sufficient pushing amount cannot be secured, and a cavity-like defect is likely to occur.
When the pin 1 and the tip of the pin 1 interfere with each other, the joining quality of the joining materials W ₁ and W _{2 on} the joining jig 18 side is impaired. Therefore, in order to secure a sufficient pushing amount of the shoulder in the subsequent friction stir welding step, it is necessary to use a pin 1 shorter than the pin 1 used in the preceding friction stir welding step in the subsequent friction stir welding step. preferable. The difference between the lengths of the pins 1 used in the preceding and subsequent friction stir welding processes is that the material W ₁ ,
Corresponds to the thinning amount of W _2.

Also, by using a pin 1 having a larger diameter than the pin 1 used in the preceding friction stir welding step in the subsequent friction stir welding step, the entrainment of air into the joint WB can be effectively performed. Can be prevented. That is, when using the pins 1 having the same diameter in the preceding and succeeding steps and filling the holes V generated in the trace of the removal of the pins 1 in the preceding friction stir welding step in the subsequent friction stir welding step, Pin 1 in the process
Is required to set the passing locus right above the hole V with high accuracy. On the other hand, in the subsequent friction stir welding process using the pin 1 having a large diameter, the positional deviation can be tolerated by an amount corresponding to the increase in the diameter of the pin 1, and the condition regarding accuracy is relaxed.

[0016]

[Example] (Example) 500 mm in width and 5000 m in length
Two extruded members of JIS 6N01 alloy having a thickness of 4 mm and a thickness of 4 mm are prepared as materials to be joined W ₁ and W ₂ , and a gantry 19 is connected via a joining jig 18 in a parallel state where both sides are butted against each other.
Fixed on top. The friction stir welding machine has a shoulder diameter of 1
An apparatus (FIG. 2) incorporating a rotating tool having a diameter of 2 mm, a pin diameter of 5.0 mm, and a pin length of 3.6 mm was used. In this case, the movable range length ML of the pin 1 was 4000 mm.

At the starting point P _1S located at one end of the butt line WL, the workpiece W
_1, W ₂ in the Insert, was run at 500 mm / min toward the other end of the rotated while pin 1 a butt line WL at 1500 rpm. An end point P _1E is set at a position 3000 mm away from the start point P _1S, and when the pin 1 reaches the end point P _1E , the pin 1 runs at the same speed and the ascending speed 500
mm / min. End point P at which pin 1 started to rise
_At a position 3.7 mm away from _1E , the pin 1 is connected to the workpiece W ₁ ,
Exited completely W _2, the inclination angle theta = 45 degrees inclined surfaces VI
Is formed.

Next, the rotary tool was replaced with a rotary tool having the same shoulder diameter and pin diameter and a pin length of 3.4 mm, and the starting point P set at a position 200 mm back from the end point P _1E to the starting point P _1S side.
Pin 2 and shoulder tip 0.2mm at joint WB with _2S
And the pin 1 was run toward the other end of the butt line WL at a speed of 500 mm / min while rotating the pin 1 at 1500 rpm. When the pin 1 reached the other end of the butt line WL, the movement of the pin 1 was stopped, and the pin 1 was pulled vertically upward. Thus, the total length 5000 of the materials W ₁ and W _{2 to} be joined is obtained.
A joining portion WB having no void defect and no air entrainment was formed over a length of 1 mm, and the joining strength also showed a high value of 60 N / mm ² or more.

(Comparative Example) When the pin 1 reached the end point P _1E , the running of the pin 1 was stopped, and the extruded sections were friction stir welded under the same conditions as in the example except that the pin 1 was pulled vertically upward. . By observing the joint WB obtained in this case, air entrapment is detected in the joint WB corresponding to the joint between the preceding and subsequent friction stir welding processes, and the joint strength at this portion is 40 N / mm ² . Had dropped significantly.

[0020]

As described above, according to the present invention, a pin is inserted into the butted portion of two materials to be joined to each other and rotated along the butting line between the materials while rotating the pin. When the long member of the material to be joined is friction stir welded in the longitudinal direction by moving the pin, the rising angle of the running pin from the abutting portion is larger than the angle α between the tip of the pin of the rotating tool and the outer periphery of the shoulder. By increasing by θ, it is possible to form a hole that is generated at the trace of pulling out the pin in the preceding friction stir welding process into a shape that is opened toward the downstream side in the welding direction, and the joining portion in the subsequent friction stir welding process Is formed, air is smoothly discharged from the holes, and a sound joint without entrainment of residual air is formed. By joining a plurality of joints formed by moving the pins within the movable range limited by the size of the friction stir welding apparatus in this way, a long member through a healthy and high-quality joint is joined. Joining becomes possible.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view of a friction stir welding method.

FIG. 2 is a schematic view of a friction stir welding apparatus used in the present invention.

FIG. 3 is an explanatory view of friction stir welding of long members.

FIG. 4 is an explanatory view of forming a joining portion over a long butt line while overlapping in a plurality of friction stir welding processes.

FIG. 5 is a joint in which a hole is formed in the trace of a pin pulled vertically upward.

FIG. 6 is an explanatory view in which a hole whose downstream side in the joining direction is opened is formed by raising a running pin.

FIG. 7 is a view showing that the shape of the open side wall surface of the hole changes depending on the ascending form of the pin;

[Explanation of symbols]

1: Pin 2: Rotor θ: The rising angle of the lower end of the pin α: The angle between the tip of the pin of the rotating tool and the outer periphery of the shoulder W ₁ , W ₂ : Material to be joined WL: Butt line WB: Joint D: Joint Direction U: Pin pull-out direction ML: Length of movable range P _1S : _Start point of preceding friction stir welding process P _1E : End point of preceding friction stir welding process P _2S : Start point of subsequent friction stir welding process P _2E : Subsequent friction stir welding Process end point V: hole S: inner wall of hole VI: inclined surface of hole

Claims (2)

[Claims] 1. A pin is inserted into a butted portion of two workpieces butted against each other, and the pins are rotated and moved along a butting line between the workpieces to friction stir weld the workpieces. The pin running during the butt line is raised from the butt portion at a rising angle (θ) larger than the angle (α) between the tip of the pin of the rotating tool and the outer periphery of the shoulder, and then the rising of the pin is started. A friction stir welding method characterized by re-inserting a pin from a position into a butt portion on the already-joined portion side, and moving the pin to an unjoined portion side of the butt line while rotating the pin. 2. A pin which is shorter than the pin used in the preceding friction stir welding by an amount corresponding to the shoulder push-in is used in the subsequent friction stir welding, and when joining the joint portion in the subsequent friction stir welding, the shoulder is used as a material to be joined. The friction stir welding method according to claim 1, wherein the pressing is performed.