JP2001170781A - Frictional agitation joining method for thick-walled member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a joined portion W without any defective cavities F in achieving the frictional agitation joining of a thick-walled member M to be joined. SOLUTION: A shoulder 2 of a rotary tool 1 is pressed into a joining surface from a first surface side of the member M to be joined with the penetration d1, and frictional-agitation-joined to the middle position in the thickness direction, and then, the shoulder 2 is pressed from the opposing surface side with the penetration d2(>d1) to form a joined portion W over the entire region in the thickness direction. The penetration is preferably set to be d1=0.1-0.3 mm, and d2=d1×(1.2-2.5). Sufficient metal is ensured in the frictional agitation joining from the opposing surface side, the joined portion W without any defective cavities F is formed, and the flatness of the first surface is also improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of friction stir welding a thick member to be welded.

[0002]

2. Description of the Related Art In friction stir welding, a rotating tool is inserted into a butt surface of a member to be welded, the rotating tool is moved on a butt line while rotating, and the metal in the vicinity of the rotating tool is caused to flow plastically. They are joined to each other. Specifically, as shown in FIG. 1, the rotary tool 1 is rotated while the shoulder 2 of the rotary tool 1 is slightly pressed into the member to be joined, and the member M to be joined is joined. The pushing of the shoulder 2 prevents the outflow of metal causing a cavity defect or the like. When the rotary tool 1 is moved along the butting line, the foremost position of the shoulder 2 is
The rotary tool 1 is tilted about 3 degrees with the tip protruding in the movement direction D so as not to interfere with the rotation tool 1. Since the member to be welded M is friction stir welded with the rear end of the shoulder 2 pushed into the member to be welded M in the moving direction D, the shoulder 2
A depression C corresponding to the indentation depth is formed on the bonding surface (FIG. 2).

[0003]

The size of the rotary tool 1 is limited due to restrictions such as strength and driving force, and the length of the pin 3 that determines the depth of the joint W is also limited. is there. Therefore, in the case of the thick member M to be joined, the friction stir welding may not be performed in one pass. In such a case,
After the member M is friction stir welded from the first surface, the shoulder 2 and the pin 3 of the rotary tool 1 are pushed into the butted surface of the member M from the opposite surface to perform friction stir welding. However, a concave portion C is formed on the first surface of the joint W by the first friction stir welding. When the member to be joined M having the concave portion C is friction stir welded from the opposite surface, a gap is generated between the member to be joined M and the backing material. Although the gap decreases during friction stir welding from the opposite side, metal is consumed to reduce the gap, and metal supply to the joint W tends to be insufficient. As a result, a cavity defect F may occur at the joint W (FIG. 3).

[0004]

SUMMARY OF THE INVENTION The present invention has been devised in order to solve such a problem, and the present invention has been made by comparing the amount of shoulder pushing in friction stir welding from the opposite surface side. It is an object of the present invention to generate a large amount of metal to compensate for the amount consumed to reduce the gap, and to form a sound joint without a cavity defect. According to the friction stir welding method of the present invention, in order to achieve the object, a pin and a shoulder of a rotary tool are pushed into the joining surface from the first surface side of the member to be joined, and the friction stir welding is performed to the middle position in the thickness direction. The shoulder is pushed into the joining surface from the opposite side with a pushing amount larger than the pushing amount from the one surface side, and the remaining unjoined portions are friction stir welded in the thickness direction. The pushing amount of the shoulder from the first surface side is preferably set in a range of 0.1 to 0.3 mm. It is preferable that the pushing amount of the shoulder from the opposite surface side is set to be in a range of 1.2 to 2.5 times the pushing amount of the shoulder portion from the first surface side. The member to be welded by friction stir welding in this manner is the first member.
Since the flatness of the surface is good, it can be used as a panel having the first surface as a design surface.

[0005]

When the thick member M is joined by friction stir welding from both front and back surfaces, the concave portion C generated by the friction stir welding from the first surface side causes metal shortage at the joint W as described above.
The cavity defect F is likely to occur. Therefore, the present inventors conducted various investigations on the effect of the concave portion C on the insufficient metal at the joint W.
As a result of research, when the shoulder press-in amount is set to be large in friction stir welding from the opposite surface side, a sufficient amount of metal for eliminating metal shortage caused by the concave portion C is supplied to the joint W, and there is no void defect F It has been found that a perfect joint W is formed. In the present specification, a section including the rotation center axis XX of the rotary tool 1 and crossing at right angles to the surface of the member M on the side where the rotary tool 1 is located and the moving direction D is from the deepest part of the shoulder 2. This refers to the distance d to the surface (FIG. 4).

The pushing amount d ₁ of the shoulder from the first surface is
Since sufficient metal is supplied to the joint W, 0.1 to
It is preferable to set the range to 0.3 mm. Sufficient metal is not supplied to the junction W in push-in amount d ₁ is less than 0.1 mm, prone to joint failure. In the pressing amount d ₁ exceeds 0.3mm Conversely, burr generation amount becomes excessive, increases the burden on the subsequent deburring step. Pushing amount d ₂ of shoulder 2 from the opposite side, when to 1.2 to 2.5 times the pressing amount d ₁ from the first surface side, the occurrence of void defects F is most effectively suppressed, In addition, the first surface is flattened to such an extent that it can be used as a design surface. If push-in amount d ₂ does not reach 1.2 times the pressing depth d _1, appears the effect of metal shortage caused by the recess C, void defects F are likely to occur at the junction W. Conversely, the pushing amount d ₂ exceeds 2.5 times the pressing depth d _1, burr is excessively generated, increases the burden on the subsequent deburring step.

[0007]

[Example] 150 mm in width, 400 mm in length, 15 m in thickness
JIS A6063 extruded profile of aluminum alloy 2
The sheet is 300mm wide and 400m long along the length direction.
m and a thickness of 15 mm to make a single plate, and fixed on a gantry. 15mm diameter shoulder 2 and 8 diameter
The shoulder 2 is pushed in from the first surface side of the member M to be joined with a pushing amount d ₁ = 0.2 mm using a rotating tool 1 having a pin 3 having a length of 7.5 mm and a length of 7.5 mm.
m, the members to be welded M were friction stir welded at a welding speed of 500 mm / min. Observation of the cross section of the joint W after the friction stir welding revealed that the member M to be joined was 7.7 mm deep from the first surface.
Was joined. Further, a concave portion C having a maximum depth of 0.5 mm was formed in the joint portion W on the first surface.

Next, the shoulder 2 and the pin 3 are pushed in from the opposite side under the same conditions except that the to-be-joined member M is inverted on the gantry and the pushing amount d ₂ is changed.
Were joined by friction stir welding to form a joined portion W over the entire region of the member M to be joined in the thickness direction. Observation of the cross section of the formed joint W, 1.2 to 2 the pushing amount d ₂ of pushing amount d _1.
In the example of the present invention maintained in the range of 5 times, as shown in Table 1, a sound joining portion W having no void defect F was obtained. The burrs generated at the joint W are small, and the maximum depth of the concave portion C formed on the first surface side is also as shallow as 0.1 mm, so that the first surface can be sufficiently used as a design surface by a slight deburring operation after the bonding. did it.

On the other hand, the same pushing amount (d ₁ , d ₂ =
In Comparative Example 1 in which the members to be joined M were friction stir welded from both the front and back sides at 0.2 mm), a cavity defect F was detected at the joint W, and the joining strength also showed a low value. Conversely, in Comparative Example 2 in which the indentation amount on the opposite surface side was increased to d ₂ = 0.6 mm, a large amount of burrs were generated, and the burden of removing burrs after friction stir welding increased. In Comparative Example 3 in which the indentation amounts for the first surface and the opposite surface were both reduced, the amount of metal supplied to the joint W during friction stir welding was insufficient.
A cavity defect F was detected at the joint W. Conversely, in Comparative Example 4 in which the indentation amounts for the first surface and the opposite surface were both increased,
The joint portion W where burrs were excessively formed was formed. As it is apparent from this comparison, the pushing amount d ₁ of the first surface side properly (preferably 0.1 to 0.3 mm) maintained at, a pushing amount d ₂ on the opposite side d ₁ × ( When maintained in the range of 1.2 to 2.5), it was confirmed that a sound bonded portion W having no void defect F was obtained, and the first surface side could be used as a design surface.

[0010]

[0011]

As described above, in the present invention, when the thick member M is friction stir welded, the first member
By setting the shoulder pushing amount on the opposite side larger than the shoulder pushing amount on the surface side, the shortage of metal caused by the concave portion generated by the friction stir welding from the first surface side is eliminated,
It forms a healthy joint without void defects. The joint formed in this way has a reduced number of concave portions during friction stir welding from the opposite surface side and is flattened, so that it can be used as a panel having the first surface as a design surface.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view when a member to be welded is friction stir welded.

FIG. 2 is a cross-sectional view showing a concave portion formed on a rotary tool side of a joint.

FIG. 3 is a cross-sectional view of a joint having a cavity defect that is likely to occur when a thick member to be joined is friction stir welded.

FIG. 4 is an explanatory view of friction stir welding according to the present invention.

[Explanation of symbols]

1: Rotary tool 2: Shoulder 3: Pin M: Member to be joined D: Moving direction C: Recess W:
Joint F: Cavity defect XX: Center axis of rotation of rotating tool d: Pushing amount of shoulder

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[Procedure amendment]

[Submission date] December 15, 1999 (1999.12.
15)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction contents]

[0010]

Continued on the front page (72) Inventor Hisashi Hori 1-34-1 Kambara, Kambara-cho, Anbara-gun, Shizuoka Prefecture Inside the Nippon Light Metal Co., Ltd. Group Technical Center No. 1 F-term in Nippon Light Metal Group Technology Center (reference) 4E067 AA01 BG00 EB00

Claims (4)

[Claims] 1. A pin and a shoulder of a rotary tool are pushed into a joining surface from a first surface side of a member to be joined, and friction stir welding is performed to an intermediate position in a thickness direction, and then a pushing amount larger than a pushing amount from the first surface side. A friction stir welding method for a thick member, characterized in that a shoulder is pushed into the joining surface from the opposite side by an amount, and the remaining unjoined portions are friction stir welded in the thickness direction. 2. The friction stir welding method according to claim 1, wherein the amount of pushing of the shoulder from the first surface side is set to 0.1 to 0.3 mm. 3. The friction stirrer according to claim 1, wherein the shoulder is pushed into the joining surface from the opposite side with a pushing amount of 1.2 to 2.5 times the pushing amount of the shoulder from the first surface side. Joining method. 4. A panel formed by friction stir welding by the method according to claim 1, wherein the first surface is a design surface.