Lap welding joint and manufacturing method thereof

Abstract

To provide a lap welding joint capable of solving a gap with a simple device configuration and a manufacturing method of the lap welding joint.SOLUTION: In manufacturing of a lap welding joint 1, a first base material 10 and a second base material 20 are prepared, the first base material 10 is overlapped on the second base material 20, and the first base material 10 and the second base material 20 are welded to each other at a welding position 2. In preparation of the first base material 10, preprocessing is performed on a preprocessing part 15 being a portion corresponding to the welding position 2 of the first base material 10. Preprocessing includes bending the preprocessing part 15 to a side of reducing a gap G2 between the first base material 10 and the second base material 20.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a butt weld joint and a method for manufacturing the same.

Background Art

[0002] Patent Document 1 discloses a method of laser welding an overlapping portion of an object to be butt-welded. In this method, in order to eliminate the gap between the objects to be welded, the amount of the gap between the objects to be welded is measured, and the irradiation position of the laser beam is changed inward from the fillet welding position of the object to be welded corresponding to the measured amount of the gap.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When using the above method, in order to realize an appropriate change in the irradiation position of the laser beam according to the amount of the gap, the laser welding apparatus becomes complicated in both hardware and software.

[0005] An object of the present invention is to provide a butt weld joint capable of eliminating a gap with a simple device configuration and a method for manufacturing the same.

Means for Solving the Problems

[0006] One aspect of the present invention provides a method for manufacturing an overlap weld joint, comprising: preparing a first base material; preparing a second base material; overlapping the first base material and the second base material with each other; and welding the first base material and the second base material to each other at a welding position. The preparation of the first base material includes performing preprocessing on a preprocessed portion, which is a portion corresponding to the welding position of the first base material. The preprocessing includes bending the preprocessed portion toward the side that fills the gap between the first base material and the second base material.

[0007] According to the above configuration, even when a gap may occur between the first base material and the second base material due to dimensional variations of the members or the like, at least at the welding position, the preprocessed portion is bent toward the side that fills the gap, so that the gap can be locally filled.

[0008] The preprocessing may include forming notches at both ends of the preprocessed portion.

[0009] According to the above configuration, when the first base material and the second base material are overlapped with each other, the preprocessed portion functions like a leaf spring. While filling the gap at the welding position, deformation of portions other than the preprocessed portion of the first base material can be suppressed.

[0010] The first base material and the second base material may be formed of an aluminum alloy.

[0011] Aluminum alloys are more likely to have dimensional variations after forming, and thus gaps, compared to, for example, steel. Even when the first base material and the second base material are formed of such an aluminum alloy, the gap can be filled at the welding position. A high-quality aluminum overlap weld joint can be provided.

[0012] The first base material may have a hat-shaped cross section, and the flange of the first base material may be overlapped with the second base material.

[0013] According to the above configuration, since the gap is clogged at the welding position, laser welding with a small beam diameter can be applied even to the fillet welding of narrow parts such as flanges. For example, the width of the flange may be in the range of 2 mm to 10 mm.

[0014] One aspect of the present invention provides a butt-welded joint including a first base material and a second base material that is butt-welded to the first base material at a welding position, wherein the first base material has a pre-processed portion at a portion corresponding to the welding position, and the pre-processed portion is bent toward the side that fills the gap between the first base material and the second base material.

[0015] According to the above configuration, even when a gap may be generated between the first base material and the second base material due to dimensional variations of the members or the like, at least at the welding position, since the pre-processed portion is bent toward the side that fills the gap, the gap can be locally filled.

Effect of the Invention

[0016] According to the present invention, it is possible to provide a butt-welded joint capable of eliminating a gap with a simple device configuration and a method for manufacturing the same.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

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Figure 8

Figure 9

Figure 10

Embodiments for Carrying Out the Invention

[0018] Hereinafter, embodiments will be described with reference to the drawings. Note that the same or corresponding elements are denoted by the same reference numerals throughout the drawings, and redundant detailed descriptions are omitted.

[0019] With reference to Fig. 6 together with Fig. 1, the manufacturing method of the fillet weld joint 1 according to the present embodiment includes preparing the first base material 10 (first preparation step S1), preparing the second base material 20 (second preparation step S2), overlapping the first base material 10 and the second base material 20 with each other (superposition step S3), and welding the first base material 10 and the second base material 20 to each other at a predetermined welding position 2 (welding step S4). The first preparation step S1 and the second preparation step S2 may be in reverse order or may be parallel.

[0020] The first base material 10 has a preprocessing portion 15 at a portion corresponding to the welding position 2. The first preparation step S1 includes performing preprocessing on the preprocessing portion 15 (preprocessing step S11) prior to the superposition step S3. In the superposition step S3, the first base material 10 is superposed on the second base material 20 in a state where the preprocessing portion 15 has already been preprocessed.

[0021] Fig. 1 shows the fillet weld joint 1 during the execution of the welding step S4. The fillet weld joint 1 includes the first base material 10 and the second base material 20 that is fillet welded to the first base material 10 at the welding position 2. The first base material 10 and the second base material 20 are joined to each other by a weld portion 3 at the welding position 2.

[0022] The first base material 10 and the second base material 20 are long. In the present embodiment, the first base material 10 and the second base material 20 extend linearly, for example, in the longitudinal direction X. A plurality of welding positions 2 are set at intervals along the longitudinal direction X of the first base material 10 and the second base material 20. The "welding position" does not refer to a position in a strict sense, but has a certain length along the longitudinal direction X. The lap welding joint 1 is provided with a plurality of welds 3 spaced apart from each other along the longitudinal direction X. Each weld 3 is in the shape of a bead extending along the longitudinal direction X. In each weld 3, the first base material 10 and the second base material 20 are line-joined. The longitudinal direction X corresponds to the welding direction (the direction in which the weld 3 extends).

[0023] In the welding step S4, various line-joining methods can be used, such as laser welding or arc welding, for example. FIG. 1 illustrates the application of laser welding. In this case, the laser beam L is irradiated onto the welding position 2, the first base material 10 and the second base material 20 are melted at the welding position 2 to form a molten pool, and the first base material 10 and the second base material 20 are joined to each other by the solidification of the molten pool.

[0024] Although detailed illustration is omitted, a manufacturing apparatus for manufacturing the lap welding joint 1 may include a laser oscillator that oscillates the laser beam L, a laser head that emits the laser beam L oscillated by the laser oscillator, a head movement mechanism that moves the laser head along the extending direction of the welding position 2 and the optical axis LA of the laser beam L, and a controller that controls the operations of the laser oscillator, the laser head, and the head movement mechanism. For example, the head movement mechanism is a vertically articulated industrial robot, and in this case, the laser head serves as an end effector of the robot.

[0025] The manufactured lap welding joint 1 is suitably applied to structural parts for vehicles, and is particularly suitably applicable to, for example, the sash flange of a door. Hereinafter, the manufacturing method of the lap welding joint 1 will be described more specifically.

[0026] FIG. 2 is a partially exploded perspective view of the first base material 10 and the second base material 20, showing one welding position 2 and its surroundings.

[0027] In the first preparation step S1, first, a plate material (blank) having a required length, width, and plate thickness T10 is prepared. Next, press working is performed on the blank as necessary. As a result, the first base material 10 is formed. The second preparation step S2 is the same. The second base material 20 is formed by preparing a blank having a required length, width, and plate thickness T20 and performing press working as necessary.

[0028] The first base material 10 and the second base material 20 are formed of a metal such as steel or an aluminum alloy. In the present embodiment, the first base material 10 and the second base material 20 are formed of an aluminum alloy. Since the aluminum alloy is lightweight and has high rigidity, the lap joint 1 is suitably applied to a structural component for a vehicle.

[0029] In the present embodiment, the second base material 20 is flat and no special press working is omitted. The second base material 20 has flat surfaces on both sides in the plate thickness direction. One of the surfaces is the second overlapping surface 20a that is overlapped with the first base material 10 in the overlapping step S3.

[0030] In the present embodiment, the first base material 10 has a hat-shaped cross section. This hat shape is imparted to the first base material 10 as a result of press working on the blank. The first base material 10 has a central wall 11 extending in the longitudinal direction X, a pair of side walls 12 extending along the height direction Z from both edges in the width direction Y of the central wall 11, and a pair of flanges 13 protruding from the tips of the pair of side walls 12, respectively.

[0031] The central wall 11 is located at the center in the width direction Y of the entire first base material 10 and is flat and extends slightly in the width direction Y. The plate thickness direction of the central wall 11 is directed in the height direction Z. The central wall 11 may be referred to as an upper wall when the first base material 10 is located above the second base material 20 and the flange 13 is directed downward, or may be referred to as a bottom wall when the first base material 10 is located below the second base material 20 and the flange 13 is directed upward.

[0032] As the pair of side walls 12 extend in the height direction Z from the central wall 11, they are inclined with respect to the height direction Z so as to move away from each other in the width direction Y. Each side wall 12 is continuously connected to the central wall 11 without a seam via a curved portion 14a, and is continuously connected to the corresponding flange 13 without a seam via a curved portion 14b.

[0033] Each flange 13 projects from the corresponding side wall 12 in the width direction Y and extends in the longitudinal direction X in the same manner as the central wall 11 and the side walls 12. The pair of flanges 13 project to opposite sides in the width direction Y.

[0034] The flange width W13 (width of the flange 13) is narrow. The flange width W13 is, for example, within the range of 2 mm to 10 mm.

[0035] The plate thickness direction of each flange 13 is directed in the height direction Z in the same manner as the central wall 11. Each flange 13 has surfaces on both sides in the height direction Z. Among the surfaces, the surface on the side opposite to the central wall 11 is the first overlapping surface 10a that is overlapped with the second base material 20 in the overlapping step S3.

[0036] The first base material 10 is provided with a pair of first overlapping surfaces 10a corresponding to each of the pair of flanges 13. Generally or ideally speaking, the pair of first overlapping surfaces 10a are on the same plane extending in the longitudinal direction X and the width direction Y.

[0037] In the overlapping step S3, the height direction Z of the first base material 10, the plate thickness direction of the flange 13, or the normal direction of the first overlapping surface 10a is made to coincide with the plate thickness direction of the second base material 20 or the normal direction of the second overlapping surface 20a. With these directions made to coincide with each other as the overlapping direction, each first overlapping surface 10a and the second overlapping surface 20a are overlapped with each other in the overlapping direction.

[0038] Aluminum alloys, for example, compared with steel, have a large springback amount and are likely to have large dimensional variations after press forming. For this reason, when a hat shape is imparted to the first base material 10 by press forming, it is difficult to strictly set the geometric tolerances of the first base material 10, such as the flatness of the first overlapping surface 10a. For this reason, the gap G1 (see FIGS. 3 to 5) between the first base material 10 and the second base material 20 (more specifically, between the first overlapping surface 10a and the second overlapping surface 20a) is likely to vary along the longitudinal direction X within one lap joint 1, and is also likely to vary for each lap joint 1.

[0039] The preprocessing step S11 is carried out as a countermeasure against the variation of the gap G1. The preprocessing includes a bending process of bending the preprocessing portion 15 on the side that closes the gap G1 between the first base material 10 and the second base material 20.

[0040] In the present embodiment, a plurality of welding positions 2 are set in the lap joint 1, and correspondingly, a plurality of preprocessing portions 15 are provided on the first base material 10 at intervals in the longitudinal direction X (see FIG. 1). Each preprocessing portion 15 has a certain length in the longitudinal direction X, similar to each welding position 2. There is an original shape portion 13a that maintains the original shape of the flange 13 before preprocessing between two adjacent preprocessing portions 15 in the longitudinal direction X. Conversely, each preprocessing portion 15 is sandwiched between two original shape portions 13a in the longitudinal direction X.

[0041] The gap G1 is the interval between the first overlapping surface 10a and the second overlapping surface 20a in the overlapping direction. The side that closes the gap G1 is one side in the overlapping direction, and is the side that relatively approaches the second overlapping surface 20a to the first overlapping surface 10a.

[0042] In this embodiment, the polymerization direction corresponds to the height direction Z of the hat shape, the thickness direction of the flange 13, and the normal direction of the first polymerization surface 10a, as described above. The "side for filling the gap G1" can be defined as the side where the side wall extends as viewed from the central wall 11 in the height direction Z, the side where the flange 13 is provided as viewed from the side wall 12 in the height direction Z, or the side opposite to the central wall 11 as viewed from the flange 13 in the height direction Z.

[0043] Hereinafter, for the sake of convenience of explanation, the "side for filling the gap G1" may be referred to as the "lower side" according to the paper surface directions of FIGS. 1 to 5, and the opposite side may be referred to as the "upper side". However, the top and bottom of the overlap welding joint 1 may be reversed, and this direction can be changed as appropriate. The surface of the flange 13 on the side opposite to the first polymerization surface 10a, that is, the upper surface, is referred to as the "outer surface 10b".

[0044] The preprocessing portion 15 is bent toward the side for filling the gap G1 by bending the preprocessing portion 15 from the outer surface 10b of the flange 13 toward the first polymerization surface 10a side. By this bending process, a bent portion 16 is provided in the preprocessing portion 15.

[0045] The bent portion 16 reaches the edge of the flange 13 in the width direction Y. The bending width W16 (the dimension in the width direction Y of the bent portion 16) is narrower than the flange width W13. Between the bent portion 16 and the curved portion 14b in the width direction Y, the original shape portion 13a of the flange 13 remains.

[0046] The bent portion 16 has a polymerization portion 16a at the central portion in the longitudinal direction X and a pair of tapered portions 16b connecting from both ends in the longitudinal direction X of the polymerization portion 16a to the original shape portion 13a of the flange 13. Each tapered portion 16b is inclined so as to go downward as it goes toward the central side of the preprocessing portion 15 in the longitudinal direction X. The polymerization portion 16a is located downward by a bending depth D16 with respect to the original shape portion 13a of the flange 13. The polymerization portion 16a is in a flat plate shape with the thickness direction facing the height direction Z and extends in the longitudinal direction X and the width direction Y. The lower surface of the polymerization portion 16a forms an offset surface 16c that partially offsets the first polymerization surface 10a downward.

[0047] Incidentally, the bending width W16 is set within an appropriate range according to, for example, the beam diameter of the laser beam L or the like. The bending depth D16 is set within an appropriate range according to the geometric tolerance of the first base material 10, the geometric tolerance of the second base material 20, the tolerance of the gap G1, and the like.

[0048] Referring to FIGS. 3 to 5, in the polymerization step S3, with the first base material 10 being pre-processed, the first polymerization surface 10a of the first base material 10 is superposed on the second polymerization surface 20a of the second base material 20. At this time, the first base material 10 and the second base material 20 are pressed against each other in the polymerization direction by a clamp (not shown). Thereby, the first polymerization surface 10a and the second polymerization surface 20a are held in a state of being superposed on each other.

[0049] At each welding position 2, an offset surface 16c as a part of the first polymerization surface 10a is in surface contact with or closely opposed to the second polymerization surface 20a. In the example shown in FIGS. 3 to 5, a slight gap G2 is formed between the offset surface 16c and the second polymerization surface 20a. This gap G2 can also be filled to zero. The gap G2 is managed so as to be an appropriate substantially constant value within the range of 0 mm to 2 mm.

[0050] In the welding step S4, the welded portion 3 is provided at the welding position 2 while the first base material 10 and the second base material 20 are pressed against each other by a clamp (not shown). At each welding position 2, the gap G2 is managed at a very small constant value. Therefore, in the welding step S4, it is not necessary to measure the gap G2 in real time. The laser head is maintained at a position necessary for focusing the laser beam L at the welding position 2 in the optical axis direction (corresponding to the height direction Z in the present embodiment), and may be scanned at a required moving speed in the welding direction (corresponding to the longitudinal direction X in the present embodiment). Even if the operation of the manufacturing apparatus is simplified in this way, high welding quality can be obtained at each welding position 2.

[0051] Therefore, according to the manufacturing method according to the present embodiment, the configuration of the manufacturing apparatus can be simplified. For example, during the scanning of the laser head, it is not necessary to perform control such as measuring the gap G2 in real time and adjusting the position of the laser head in the optical axis direction according to the measurement result of the gap. For this reason, means for measuring the gap can be omitted both in terms of hardware and software, and construction and implementation of a program for position control based on the measured value of the gap can be omitted.

[0052] In the original shape portion 13a, the gap G1 is not managed like the preprocessing portion 15, but it does not have a significant influence on the welding quality. In the preprocessing portion 15, high welding quality can be obtained by locally managing the gap G2.

[0053] When the first base material 10 and the second base material 20 are formed of an aluminum alloy, it is difficult to manage the gap at the welding position 2, and thereby it is difficult to narrow the flange width W13 of the overlap weld joint 1. When press forming is used in the first preparation step S1 or the second preparation step S2 for imparting a complex shape such as a hat shape, it is even more so. In this example, the gap G2 can be managed at a small value at the welding position 2. Therefore, even if the flange width W13 is narrow, an overlap weld joint 1 made of an aluminum alloy can be provided. Since the flange width W13 can be narrowed, laser welding with a reduced beam diameter is also possible.

[0054] Next, with reference to FIGS. 7 to 10, the overlap weld joint 1 and its manufacturing method according to the second embodiment will be described focusing on the differences from the first embodiment.

[0055] Also in the overlap weld joint 1 according to the present embodiment, the first base material 10 has a preprocessing portion 15 at a portion corresponding to the welding position 2. The preprocessing portion 15 includes a bending portion 16 and a pair of notches 17 adjacent to both ends in the longitudinal direction X of the bending portion 16. The preprocessing step S11 includes a bending step of forming the bending portion 16 in the preprocessing portion 15 and a trimming step of forming a pair of notches 17 at both ends of the preprocessing portion 15. The order of the bending step and the trimming step is not particularly limited.

[0056] Each notch 17 has a vertex portion 17a set on the flange 13, an opening portion 17b opened at the edge in the width direction Y of the flange 13, and a pair of inner bevel edges 17c and outer bevel edges 17d extending from the vertex portion 17a toward the opening portion 17b.

[0057] Each notch 17 expands in the width direction Y as it goes from the vertex portion 17a toward the opening portion 17b. The inner bevel edge 17c and the outer bevel edge 17d are inclined with respect to the width direction Y so as to face each other in the longitudinal direction X as they go from the vertex portion 17a toward the opening portion 17b. The vertex portion 17a, the inner bevel edge 17c, and the outer bevel edge 17d are triangular in shape when viewed in the height direction Z.

[0058] The inner bevel edge 17c forms the edge in the longitudinal direction X of the bent portion 16, and the outer bevel edge 17d forms the edge of the original shape portion 13a. The notch 17 is interposed between the bent portion 16 and the original shape portion 13a in the longitudinal direction X, whereby the bent portion 16 is separated from the original shape portion 13a in the longitudinal direction X.

[0059] The bent portion 16 is the portion between the pair of inner bevel edges 17c in the longitudinal direction X. In the width direction Y, the original shape portion 13a of the flange 13 is left between the bent portion 16 and the curved portion 14b. The bent portion 16 has an outer overlapping portion 16a in the width direction Y and a tapered portion 16b connecting the overlapping portion 16a to the original shape portion 13a in the width direction Y. The overlapping portion 16a is located below the original shape portion 13a of the flange 13 by the bending depth D16. The overlapping portion 16a is in a flat plate shape with the plate thickness direction facing the height direction Z and extends in the longitudinal direction X and the width direction Y. The lower surface of the overlapping portion 16a forms an offset surface 16c.

[0060] Also in this embodiment, in the same manner as in the first embodiment, the gap G2 can be managed at the welding position 2, and the manufacturing apparatus can be simplified.

[0061] In the present embodiment, when the first base material 10 and the second base material 20 are pressed against each other by a clamp (not shown) in the polymerization step S3, the bent portion 16 functions like a leaf spring. At this time, the original shape portion 13a adjacent to the bent portion 16 in the longitudinal direction X is separated from the bent portion 16 by the notch 17. Therefore, even if the clamping force is increased, deformation of the original shape portion 13a can be suppressed. In this way, it is possible to achieve both managing the gap G2 with a small value and suppressing deformation of the first base material 10.

[0062] Although the embodiments have been described so far, the above configuration can be appropriately changed within the scope of the gist of the present invention.

[0063] For example, the first base material 10 and the second base material 20 do not necessarily extend linearly and may be curved in the height direction Z or the width direction Y. When curved in this way, the gap between the first base material 10 and the second base material 20 becomes more likely to vary. By applying the manufacturing method according to the present embodiment, it becomes easier to manage the gap G2 at the welding position 2. Thus, the manufacturing method according to the present embodiment is also beneficial in that it can easily manufacture the curved lap welded joint 1.

[0064] The first base material 10 and the second base material 20 may be formed of other metals such as steel. A pre-processed portion bent toward the side of filling the gap G1 may also be provided at a portion corresponding to the welding position of the second base material 20. The second base material 20 is not limited to a flat plate shape and may have, for example, a hat-shaped cross section.

[0065] The lap welded joint 1 is not limited to the sash flange of a vehicle door and is applicable to other vehicle structural parts as well as structural parts other than vehicles.

[0066] The present disclosure may include the following aspects. (Aspect 1) Prepare a first base material, Prepare a second base material, Superpose the first base material and the second base material on each other, Welding the first base material and the second base material to each other at the welding position, comprising: Preparing the first base material includes performing preprocessing on a preprocessed portion that is a portion corresponding to the welding position of the first base material, The preprocessing includes bending the preprocessed portion on the side that fills the gap between the first base material and the second base material, Method for manufacturing a fillet weld joint. (Aspect 2) The preprocessing includes forming notches at both ends of the preprocessed portion, Method for manufacturing a fillet weld joint according to Aspect 1. (Aspect 3) The first base material and the second base material are formed of an aluminum alloy, Method for manufacturing a fillet weld joint according to Aspect 1 or 2. (Aspect 4) The first base material has a hat-shaped cross-section, and the flange of the first base material is overlapped with the second base material, Method for manufacturing a fillet weld joint according to any one of Aspects 1 to 3. (Aspect 5) The width of the flange is in the range of 2 mm to 10 mm, Method for manufacturing a fillet weld joint according to Aspect 4. (Aspect 6) A first base material, A second base material that is fillet welded to the first base material at the welding position, comprising: The first base material has a preprocessed portion at a portion corresponding to the welding position, and the preprocessed portion is bent on the side that fills the gap between the first base material and the second base material, Fillet weld joint.

Explanation of reference numerals

[0067] 1 Fillet weld joint 2 Welding position 3 Welded portion 10 First base material 10a First overlapping surface 10b Outer surface 11 Central wall 12 Side wall 13 Flange 13a Original shape part 14a, 14b Bending part 15 Preprocessing part 16 Bending part 16a Overlapping part 16b Taper part 16c Offset surface 17 Notch 17a Vertex part 17b Open part 17c Inner bevel edge 17d Outer bevel edge 20 Second base material 20a Second overlapping surface L Laser beam LA Optical axis G1, G2 Gap D16 Bending depth T10, T20 Plate thickness W13 Flange width W16 Bending width S1 First preparation process S11 Preprocessing process S2 Second preparation process S3 Overlapping process S4 Welding process

Claims

1. Prepare a first base material, Prepare a second base material, Overlap the first base material and the second base material with each other, Weld the first base material and the second base material to each other at the welding position, comprising: The preparation of the first base material includes performing pre-processing on a pre-processed part that is a part corresponding to the welding position of the first base material, The pre-processing includes bending processing for bending the pre-processed part on the side that fills the gap between the first base material and the second base material, A method for manufacturing an overlap welded joint.

2. The pre-processing includes forming notches at both ends of the pre-processed part, The method for manufacturing an overlap welded joint according to Claim 1.

3. The first base material and the second base material are formed of an aluminum alloy, The method for manufacturing an overlap welded joint according to Claim 1 or 2.

4. The first base material has a hat-shaped cross section, and the flange of the first base material is overlapped with the second base material, The method for manufacturing an overlap welded joint according to Claim 3.

5. The width of the flange is within the range of 2 mm to 10 mm, The method for manufacturing an overlap welded joint according to Claim 4.

6. A first base material, A second base material that is overlap welded to the first base material at the welding position, comprising: The first base material has a pre-processed part at a part corresponding to the welding position, and the pre-processed part is bent on the side that fills the gap between the first base material and the second base material, An overlap welded joint.

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