JPH1158039A - Lap joint by friction-stirring-joining and formation thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain the concentration of stress on a joined part and to improve the reliability to the strength of the joined part by integrally forming projections for joining on the lapping side surface of a first work, abutting to the lapping side surface of a second work as T-shape and executing friction-stirring-joining. SOLUTION: The projections la, 2a for joining are formed on the lapping side surface at the tip part of each side edge part of both of the first and the second plate-like works l, 2 with an extruding-integral-formation. Both side edge parts of the works l, 2 are lapped from the upper and the lower directions and combined. The tip surface of the projection la for joining of the first work l is abutted on the surface at the lapping side of the second work 2, and the projection la for joining and the second work 2 are combined as T-shape. The projection 2a for joining of the second work 2 and the first work l are combined as T-shape, too. In these lapping states, the works 1, 2 are joined by the friction- stirring-joining. In the joining, a rotary 3 is used as a tool for joining.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a lap joint by friction stir welding and a method for forming the same.

[0002]

2. Description of the Related Art For example, as shown in FIG. 6, a lap joint has conventionally been used as a lap joint in a case where side edges of two plate-like works made of metal such as aluminum are joined in a state of being overlapped. Then, the side edges of the two plate-shaped works (51) and (52) are overlapped with each other, and welding such as MIG welding is performed at the corner of the end of the side edge of the one plate-shaped work (51). 53) At the same time, another type of plate-like work (52) is widely used in which a joint such as MIG welding is welded (53) at the corner at the tip of the side edge.

On the other hand, recently, studies have been made to use a joining method called friction stir welding for joining in such a case.

In this friction stir welding method, works are solid-phase welded to each other, and a rotor (3) as shown in FIG. 5A is used as a tool. The rotor (3) is attached to the tip shaft of the cylindrical rotor body (9).
A pin-like friction stir probe (4) having a smaller diameter than that of the above is protruded coaxially and integrally, and is made of a material such as steel which is hard and excellent in heat resistance.

As shown in FIG. 5 (a), the tip of the probe (4) is connected to the plate-like workpieces (51) and (52) while rotating the rotor (3) around its own axis, as shown in FIG. In the widthwise center or middle part of the side edge overlapping part area of
One of the plate-like works (52) is brought into contact with the pressed state, and the frictional heat softens and plasticizes the contact part. Then, the rotor (3) is further pressed against the work (52),
The probe (4) is inserted in the thickness direction so as to reach the thickness of both the works (52) and (51), and the shoulder (6) at the tip of the cylindrical rotor body (9) is inserted into the work (52). Make contact with the pressed state. Thereafter, while maintaining the rotating state, the rotor (3) is moved along the overlapping portion of the two works (51) and (52) as shown in FIG. In the portion where the rotor (3) passes, the surrounding material is softened and stirred by the frictional heat generated by the rotation of the rotor (3), and is scattered by the shoulders (6) of the cylindrical rotor body (9). After being plastically flown so as to fill the passage groove of the probe (4) while being regulated, the heat is rapidly lost and solidified by cooling. In this way, the softening, close deformation, stirring, and cooling and solidification of the material in the overlapping portion are performed by the rotor (3)
The work (51) and (52) are integrated with each other at the overlapping portion and sequentially joined (7).

In this friction stir welding method, the workpieces (51) and (52) are joined in a softened state without melting the material, and there is a problem in quality due to heat influence and the like as in the case of welding. A high-quality joint (7) can be formed without generation.

[0007]

However, in the lap joint by welding such as MIG as described above, the side edge overlapping surfaces (55) (5) of the two plate-shaped works (51) and (52) are provided.
6) The workpieces (51) and (52) are in an unjoined state.
When stress is applied to the joint, the welded joint (53) (53)
In addition, there is a danger that stress is concentrated due to the notch effect of the unjoined portions (55) and (56) and cracks and cracks are generated in the joined portions (53) and (53). Was not always good.

In particular, the overlapping surfaces (55) and (56) of the workpieces (51) and (52) are almost in contact with each other, and therefore, the unjoined overlapping portions (55) and (5)
The notch effect due to 6) becomes sharp, and the joint (5
3) The stress concentration on (53) is increased.

[0009] Also, in the lap joint by friction stir welding as described above, the non-joined lap portions (55) (5) (5) (5) which are almost in contact with each other in the same manner as described above on both sides of the joint (7).
6), the sharp notch effect increases stress concentration on the joint (7), and the strength reliability of the joint (7) is not necessarily improved. There's a problem.

SUMMARY OF THE INVENTION In view of the above problems, the present invention can suppress and alleviate the concentration of stress at the joint due to the notch effect of the unjoined overlapped portion, and can reduce the stress at the joint. An object of the present invention is to provide a lap joint having a structure capable of improving strength reliability and a method of forming such a lap joint.

[0011]

The object of the present invention is to form a joining projection integrally with a surface of the first work on the overlapping side, and to form a T-shaped joining projection on the surface of the second workpiece on the overlapping side. The lap joint by friction stir welding is characterized in that the joining protrusion and the second work are friction stir welded.

A joining projection integrally formed on the surface of the first workpiece on the overlapping side is brought into contact with the surface of the second workpiece on the overlapping side in a T-shape, and friction is applied from the back side of the second workpiece. The problem is solved by a method of forming a lap joint, characterized in that a stir welding tool is operated to friction stir weld the joining protrusion and the second work.

The lap joint according to the present invention utilizes a T-joint formed by friction stir welding, and a joint having high strength and reliability can be obtained by combining the two. In other words, the entire joining portion of the first work can be joined to the overlapping surface of the second work by friction stir welding. Therefore, a gap formed by the joining projection exists on the side of the joining portion, and the gap reduces the notch effect and suppresses or alleviates stress concentration on the joining portion. Therefore, even if stress is applied to the work, large stress concentration does not occur at the joint, and the strength reliability of the joint is improved.

[0014]

Next, embodiments of the present invention will be described with reference to the drawings.

In the embodiment shown in FIGS. 1 and 2, the first and second metal workpieces (1) and (2) are joined with their side edges overlapped. When applied to the lap joint.

The first and second plate-like workpieces (1) and (2) in the present embodiment are made of an extruded aluminum material, and as shown in FIG. On the surface on the overlapping side of the tip of the
a) (2a) is formed by integral extrusion molding.

As shown in FIG. 1B, the two works (1) and (2) are combined so that their side edges are overlapped from the top and bottom. In this combination, the distal end surface of the joining protrusion (1a) of the first work (1) abuts on the surface on the overlapping side of the second work (2), and the joining protrusion (1a) and the second work ( 2) are combined in a T-shape. In addition, the distal end surface of the joining protrusion (2a) of the second work (2) is also in contact with the surface on the overlapping side of the first work (1), and the joining protrusion (2a) and the first work (1) are contacted. Are combined in a T-shape. Projection for both joints (1
In a) and (2a), a predetermined interval is provided in the width direction in this combined state. Using this interval,
Then, the work (1) (2) can be absorbed by friction stir welding. Joining is
A rotor (3) as shown in FIG. 2 (c) is used as a joining tool.

The probe (4) of the tool (3) has a conical portion (4b) whose diameter increases from the distal end to the proximal end, and the base of the conical portion (4b). It has a configuration in which a large-diameter cylindrical portion (4a) is integrally and continuously provided on the end side. A screw (5) is formed on the outer peripheral surface of the probe (4) in both the conical portion (4b) and the columnar portion (4a). The rotator (3) is driven to rotate in the direction opposite to the spiral direction of the screw (5), and during rotation insertion of the probe (4) into the meat of the work, the probe (4) is moved to the work. The urging is performed in a direction opposite to the insertion direction, and the meat softened by the reaction force of the urging force is effectively stirred. In addition, instead of the screw (5), various grooves and irregularities may be formed on the outer peripheral surface of the probe (4). The shoulder (6) is inclined so as to be concave from the outer peripheral edge toward the probe (4).

Using the rotor (3), first, the joining protrusion (1a) of the first work (1) and the second work (2) are friction stir welded (7). That is, as shown in FIG. 2C, while rotating the rotor (3), the probe (4) is moved from the back side of the second work (2) to the meat of the second work (2). The first work (1) is inserted so as to reach the meat of the joining protrusion (1a) of the first work (1). The insertion depth is
The conical surface of the conical portion (4a) of the probe (4) is placed on both corners of the joining projection (1a) and the second work (2).
The depth is set so as to be as close as possible so as not to cause a joint failure. Thus, the joining protrusion (1a) can be properly joined to the second work (2) over the entire area in the width direction. Thereafter, the rotor (3) is moved in the longitudinal direction of the overlapping portion while maintaining the inserted state of the probe (4). Thereby, the first
Projection (1a) for joining work (1) and second work (2)
Are subjected to friction stir welding (7).

Then, as shown in the drawing, the joining protrusion (2a) of the second work (2) and the first work (1) are connected to the rotor probe (4) and the first work ( 1) is inserted from the back side of the first work (1) through the meat of the first work (1) so as to reach the meat of the joining projection (2a) of the second work (2). ). As described above, the lap joint of the two works (1) and (2) shown in FIG.

In the lap joint formed as described above, the joining projections (1a) (2) are formed on the workpieces (1) and (2).
a) is formed integrally, and this is abutted against the workpieces (2) and (1) in a T-shape to perform friction stir welding (7) and (7). Therefore, each joining projection (1a) is formed. (2a) can be joined (7) (7) to the opposing workpieces (1) and (2) over the entire width direction of the tip end surface. Therefore, the joining protrusions (1a) (2)
There is a gap (8) formed by a), which reduces the notch effect,
Stress concentration on the joints (7) and (7) is suppressed or reduced. Therefore, even if stress is applied to the joined workpieces (1) and (2), a large stress concentration does not occur at the joints (7) and (7), and the joints (7) and (7) are It is excellent in strength reliability.

In addition, since the joining projections (1a) and (2a) are provided, and the joining projections (1a) and (2a) are joined to the workpieces (2) and (1) to form a lap joint. For example, for example, there is a variation in the width dimension of each of the works (1) and (2), so that the area range of the overlapping portion of the side edges of the works (1) and (2) fluctuates in size. However, it is possible to make the joints (7) and (7) of the lap joint into joints with reduced stress concentration and high strength and reliability while coping with the fluctuation.

FIGS. 3 and 4 show various modifications of the present invention. FIG. 3 (a) shows an example in which only one workpiece (1) is provided with a joining projection (1a) and friction stir welding is performed. As described above, the joining projection (1a) may be provided on at least one of the workpieces (1). Fig. 3 (b)
A groove (1b) is provided at a predetermined interval from the tip of the side edge of one of the workpieces (1), and a joining projection (1a) is formed by the groove (1b) to perform friction stir welding. The projection may be formed in such a form. FIG.
(C) shows the joining projection (1) on the other workpiece (2) (1).
a) Grooves (2c) and (1c) into which (2a) is fitted are formed, and friction stir welding is performed. By forming the grooves (2c) and (1c) for fitting the joining projections (1a) and (2a) in this manner, even if a normal tool (3) as shown in FIG. A friction stir welding part can be formed. FIG. 4 (d) shows a joint of the type in which the entirety of the second work (2) is overlapped and joined to the first work (1). Can also be applied. That is, the present invention is not limited to the lap joint between the side edges of the plate-shaped work,
It is applicable to various types of lap joints. FIG. 4E shows a form in which a plate-shaped second work (2) is superimposed on a block-shaped first work (1). Can also be applied. That is, both the workpieces do not need to be plate-shaped workpieces, and are widely used as lap joints between workpieces of various modes. In the above embodiment, the work (1) and the work (2) are described using an aluminum material, but a metal material other than aluminum may be used.

[0024]

As described above, according to the present invention, the lap joint by friction stir welding and the method for forming the same are provided by joining the joining projection integrally formed on the lapping side surface of the first workpiece with the second workpiece. Since the abutting surface is abutted in a T-shape and the joining protrusion and the second work are friction stir welded, stress is concentrated on the joining portion due to the notch effect of the unjoined overlapping portion. Can be suppressed or alleviated, and the strength reliability of the joint can be improved.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention. FIG. 1A is a cross-sectional view showing each work in a separated state, and FIG.

FIG. 2 shows the same embodiment, in which FIG. 3C is a cross-sectional view showing a state during friction stir welding, and FIG. 2D is a cross-sectional view of the obtained lap joint.

FIGS. 3A to 3C are cross-sectional views showing a modified example of the lap joint of the present invention.

FIGS. 4 (d) and 4 (e) are cross-sectional views showing still another modified example of the lap joint of the present invention.

FIG. 5 shows an example of forming a lap joint by friction stir welding. FIG. 5A is a cross-sectional view, and FIG. 5B is a plan view.

FIG. 6 is a cross-sectional view showing a conventional example of a lap joint.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... 1st workpiece 2 ... 2nd workpiece 1a, 2a ... Joining protrusion 3 ... Rotor (friction stir welding tool) 7 ... Joining part 8 ... Gap

Claims (2)

[Claims] 1. A joining projection is integrally formed on a surface of the first workpiece on the overlapping side, and the joining projection is abutted in a T-shape on a surface of the second workpiece on the overlapping side. A lap joint by friction stir welding, wherein the projection for use and the second workpiece are friction stir welded. 2. A joining projection integrally formed on a surface of the first workpiece on the overlapping side is brought into contact with the surface of the second workpiece on the overlapping side in a T-shape, and friction is applied from the back side of the second workpiece. A method of forming a lap joint, wherein a stir welding tool is operated to friction stir weld the joining protrusion and the second work.