JP2005111533A - Friction stir welding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a friction stir welding method capable of attaining excellent joining without any special work such as cutting even when a gap is present between workpieces to be joined. <P>SOLUTION: Two workpieces P1 and P2 are abutted on each other to form a joining line between them. Friction stir welding is performed by feeding a filler S while moving a joining tool 1 along the joining line at a predetermined joining speed. The feed speed of the filler S is determined on the basis of the magnitude of the gap between the two workpieces P1 and P2 to be joined and the joining speed. The filler S is formed of the same material as the two workpieces P1 and P2, or a material which can be a welding material thereof. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a friction stir welding method, and is particularly suitable for joining extruded shapes used for manufacturing a railway vehicle structure.

  In general, a structure (vehicle body) of a railway vehicle includes a side structure that forms a side surface portion of the vehicle body, a roof structure that forms a roof portion of the vehicle body, and a bogie frame that forms a floor portion. When manufacturing such a structure, first, a plurality of extruded shapes are joined to produce a side structure, a roof structure, and a frame.

  The extruded shape member used for manufacturing the side structure, the roof structure, and the underframe has a length of about 20 m and a width of about 35 cm. For this reason, when it is going to butt | join and join such a large extruded shape member, the clearance gap produced in the butt | matching part may become large.

  For example, as shown in FIGS. 3A and 3B, when two materials P11 and P12 or P11 'and P12' are abutted, non-uniform gaps T and T 'are generated between them.

  When the gaps T and T 'of the groove become so large as to exceed Δt (Δt') = 1.0 mm, an internal defect occurs in the case of the hollow extruded shape member made of the aluminum alloy.

  Therefore, even if there is a gap between the two materials to be joined, a plate-shaped filler is arranged in advance in the gap between the butted portions of the two materials to be joined, and the joining tool It has been proposed that the three members be friction stir welded in a state where the filler and the two materials to be joined are positioned within the projection range (see, for example, Patent Document 1).

Moreover, even when the gap between the materials to be joined is large, the two materials to be joined are abutted so as to be able to be joined well, and the abutting surface is cut along the joining line, which is caused by the cutting. It has also been proposed to insert a filling material into the gap and perform friction stir welding along the joining line (see, for example, Patent Document 2).
JP 2000-233285 A (see paragraph numbers 0049 to 0053 and FIGS. 14 and 15) JP 2003-154473 A (see paragraph numbers 0010 to 0019 and FIGS. 1 and 2)

  Prior to the joining work, in the technique described in Patent Document 1, it is necessary to previously arrange a plate-like filler in the gap between the butted portions of the two materials to be joined, and the technique described in Patent Document 2 described above. Then, the butt surface must be cut along the joining line, and the work prior to the joining work is troublesome.

  The present invention provides a friction stir welding method capable of satisfactorily joining even if there is a gap between the materials to be joined without performing any special work such as placement of the filler or cutting prior to the work. For the purpose.

  According to the first aspect of the present invention, friction stir welding is performed by joining two materials to be joined, forming a joining line therebetween, and moving the joining tool along the joining line at a predetermined moving speed. A friction stir welding method for supplying a filler (melting material) that is the same material as the two materials to be joined or a welding material thereof to a gap formed between the two materials to be joined. However, the friction stir welding is performed along the joining line. Here, the supply of the filler includes not only the case of automatically supplying mechanically using a supply device or the like, but also the case of supplying manually by an operator. In the case of automatic supply, the moving speed of the joining tool or the supply speed of the filler is appropriately adjusted according to the gap. When supplying manually, an operator will adjust a supply speed suitably, seeing a clearance gap.

  In this way, the filler that is the same material as the two materials to be joined or the welding material thereof is supplied to the gap formed between the two materials to be joined. The filler is stirred together with the two materials to be joined, and the filler compensates for a material shortage corresponding to the gap. Therefore, unlike the conventional method, the friction stir welding can be performed satisfactorily even if there is a gap between the two materials to be joined without performing any special work such as placement of the filler or cutting prior to the work. It becomes possible.

  As described in claim 2, prior to the movement of the joining tool, the size of the gap between the two materials to be joined is measured, and the filler is determined based on the size of the gap and the moving speed of the joining tool. It is desirable to determine the supply speed supplied to the gap.

  In this way, the gap between the two workpieces is measured, and the filler is supplied at a supply speed determined based on the size of the gap and the moving speed of the welding tool. The amount of filler supplied is adjusted in accordance with the size of the gap, and the friction stir welding is satisfactorily performed, even if the moving speed of the welding tool is not constant and changes.

  In this case, as described in claim 3, the gap between the two materials to be bonded is the gap between the two materials to be bonded from above the two materials to be bonded by a photographing means (for example, a CCD camera). It can be set as the structure which image | photographs and detects the width | variety of the said clearance gap as a magnitude | size of the said clearance gap based on the imaging | photography result. This width detection may be performed continuously or intermittently.

  If it does in this way, the width | variety of a gap will be detected by image | photographing the clearance gap between two to-be-joined materials from an upper side (of 2 to-be-joined materials) prior to joining (stirring) with an imaging | photography means. Therefore, the width of the gap is easily calculated by performing image processing on the image signal from the photographing means. Since the size of the gap is approximated by the width of the gap that can be easily measured from the upper side, it is easy to detect the size of the gap.

  It is also effective in some cases to warm the filler before supplying it to the gap. This is because the pre-warmed filler is supplied to the gap, so that the warmed filler is smoothly stirred together with the base material (two materials to be joined) during stirring by the joining tool.

  Since it comprised as mentioned above, since the present invention carries out friction stir welding, supplying the filler used as the same material as the above-mentioned two joined materials, or those welding materials, to the crevice between two joined materials, The filler can be agitated together with two materials to be joined (base materials), and can be joined well regardless of the size of the gap between the grooves. Therefore, the tolerance of the gap of the groove increases.

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

  FIG. 1 is a schematic side view showing a main part of a friction stir welding apparatus used in the friction stir welding method of the present invention, and FIG. 2 is a schematic plan view thereof.

  As shown in FIGS. 1 and 2, the friction stir welding apparatus used in the friction stir welding method of the present invention has a filler S (on the front side of a welding tool 1 for friction stir welding of two workpieces P1 and P2. A filler supply device 2 for supplying a wire is provided. The filler S is supplied by the filler supply device 2 in a portion that is actually friction stir welded by the welding tool 1 or a portion slightly ahead of it.

  The joining tool 1 and the filler supply device 2 are attached to a movable frame (not shown) and are configured to move together while maintaining a certain positional relationship. Here, although the filler supply device 2 is not specifically illustrated, the filler supply device 2 can adjust the supply speed of the filler S, and the filler S can be joined to the materials to be bonded P1 and P2 so as to be friction stir welded. The same material or a material that becomes a welding material thereof is used.

  The joining tool 1 is provided in an inclined state such that the lower the central pin 1a is, the more forward the traveling direction is. When performing friction stir welding, as is well known, the welding tool 1 is lowered while rotating and moved on the bonding line between the workpieces P1 and P2 mounted on the upper side of the gantry. As a result, frictional heat is generated at the contact portion between the shoulder portion 1b of the welding tool 1 and the materials to be joined P1 and P2, and the material to be joined P1 and P2 in the vicinity of the shoulder portion 1b and the joining line is agitated. Both members are friction stir welded.

  In addition to the joining tool 1 and filler supply device 2, the movable frame is provided with a CCD camera 3 (photographing means) at a certain distance on the front side of the joining tool 1. The CCD camera 3 is attached so as to photograph the front in the traveling direction of the welding tool 1 from above through the lens 3a. The CCD camera 3 photographs the width (gap) of the two materials to be joined P1 and P2 from above, and the photographing signal is sent to a controller (for example, composed of a microcomputer) (not shown) to perform certain processing such as image processing. By performing this process, the size of the gap between the two materials to be joined P1 and P2 is obtained. That is, in this way, the size of the gap between the two materials to be joined P1 and P2 is measured. Further, an illumination device 4 that illuminates a portion to be photographed is attached to the CCD camera 3 via an attachment bracket 5.

  The filler supply device 2 supplies the filler S to the gap between the two members P1 and P2 prior to the passage of the welding tool 1, and at the time of friction stir welding, the joining line of the materials to be joined P1 and P2 The filler S is also stirred together with the nearby materials, and plastic fluidizes. The filler supply speed is based on the size of the gap (measured by photographing with the CCD camera 3 and the like) and the moving speed of the welding tool 1 (set on the operation panel of the friction stir welding apparatus). Is calculated and determined by This calculation / determination is performed based on mathematical formulas described later. The larger the gap size and the faster the moving speed of the joining tool, the faster the filler S supply speed.

  In this way, by supplying an appropriate amount of filler S to the gap between the two materials to be joined P1 and P2, the two materials to be joined P1 and P2 are almost the same as when there is no gap between them. Good joints are formed. After that, the welding tool 1 is pulled upward, and the friction stir welding is completed when the joint is cooled and hardened.

  Next, a method for friction stir welding using the above apparatus will be described.

  First, two plate-shaped workpieces P1 and P2 (a long extruded shape made of an aluminum alloy) are placed on a gantry and the joining edges of these workpieces P1 and P2 are butted (this butted portion). Becomes a joint line) and is clamped in that state.

  Then, if necessary, the butted portions of the materials P1 and P2 are temporarily fixed and welded at predetermined intervals by MIG welding or the like. This is to prevent the workpiece from being disassembled apart during friction stir welding.

  Due to the movement of the movable frame, the CCD camera 3 moves together with the joining tool 1 and the filler supply device 2 and is in front of the traveling direction of the joining tool 1 (this is also in front of the portion where the filler supply device 2 supplies the filler). ) Always shoot the joint line from above. That is, the gap between the two bonding materials P1 and P2 is photographed. Since photographing is performed while illuminating by the illumination device 4, the width of the gap between the two workpieces P1 and P2 is clearly photographed prior to friction stir welding.

  When the friction stir welding is performed, the welding tool 1 moves while rotating on a welding line that is a butt portion between the two materials P1 and P2. Filler S is supplied to the moving part of the welding tool 1 (the part of the gap constituting the welding line) at a filler supply speed V1 determined as described later. It is sufficient that the filler S to be supplied is supplied at room temperature. However, in order to increase the efficiency of friction stir welding, the filler S is supplied after being heated in advance by a heating device (not shown) (for example, incorporated in the filler supply device 2). It is also possible to make it.

  While the welding tool 1 rotates at a predetermined moving speed (joining speed) while rotating along the joining line, since the filler S for filling the gap is supplied in advance to the part, The joining materials P1, P2 and the filler S are agitated together, and as a result, the two materials to be joined P1, P2 are satisfactorily friction stir joined at the joining line.

  At this time, the CCD camera 3 carried together by the movable frame photographs the front of the joining tool 1 in the traveling direction, and the photographing signal is sent to a controller including an image processing device (not shown). In the controller, certain processing is performed on the photographing signal by well-known image processing by an image processing apparatus, and the gap between the two materials to be joined P1 and P2 is calculated. In this way, the gap between the two materials to be joined P1 and P2 is measured.

Then, in the controller, the filler supply speed V1 is determined based on the size (width) of the gap and the joining speed (moving speed of the movable frame). Specifically, the filler supply rate V1 is calculated by the following equation. The following formula is calculated on the assumption that the gap between the two materials to be joined P1 and P2 has a uniform width in the thickness direction.

| V1 | = | b · t / (π · d 2/4) · V | - | V |

V1: Filler supply speed
b: groove gap
t: Joint plate thickness
π: Pi ratio
d: Filler diameter
V: Joining speed of the joining tool 1 For example, in the case of an aluminum alloy to be joined (base material) having a thickness of 4.5 mm, the joining tool moving speed is 600 mm / min, and the gap (width) of the groove is 0.5 mm. In this case, a filler (diameter of 1.6 mm) suitable for the material to be bonded may be supplied to the gap (bonding line) between the materials to be bonded at a supply rate of 71 mm / min.

It is a schematic side view which shows the principal part of the friction stir welding apparatus used for the friction stir welding method of this invention. It is the same schematic plan view. It is explanatory drawing of the state which faced | matched two to-be-joined materials.

Explanation of symbols

P1, P2 Materials to be joined 1 Joining tool 2 Filler supply device 3 CCD camera (photographing means)
3a lens 4 lighting device 5 mounting bracket S filler

Claims (4)

This is a friction stir welding method in which two workpieces are butted together to form a bond line between them, and the friction stir welding is performed by rotating the welding tool along the welding line at a predetermined moving speed. And
Friction stir welding is performed along the joining line while supplying the same material as the two materials to be joined or a filler serving as a welding material to the gap formed between the two materials to be joined. A friction stir welding method characterized by the above.   Prior to the movement of the welding tool, the size of the gap between the two materials to be joined is measured, and the supply speed for supplying the filler to the gap is determined based on the size of the gap and the moving speed of the welding tool. The friction stir welding method according to claim 1 to be obtained. The gap between the two materials to be joined is photographed by the photographing means from above the two materials to be joined,
The friction stir welding method according to claim 2, wherein the width of the gap is detected as the size of the gap based on the photographing result. The friction stir welding method according to any one of claims 1 to 3, wherein the filler is heated before being supplied to the gap.

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