JP5239366B2 - Laser welding method, laser welding apparatus, and welding member - Google Patents

Description

  The present invention relates to a laser welding method, a laser welding apparatus, and a welding member.

  A laser welding method for welding a plurality of welding members by irradiating a laser beam is known. In general, in the laser welding method, a welded part is welded by scanning a laser beam linearly at a welding location.

In order to improve the welding strength, a method has been proposed in which a laser beam is scanned in a loop shape to increase the welding length (see Patent Document 1).
JP 2000-145450 A

  However, since the welding length is made longer than necessary, the welding operation becomes inefficient.

  An object of the present invention is to provide a laser welding method, a laser welding apparatus, and a welding member that can improve the welding strength between welding members at an arbitrary position of a welding location and can prevent welding failure.

  The present invention moves the laser beam relative to the member while scanning the laser beam in a first scanning direction along a welding locus for welding a plurality of superimposed members. A weld expanded in the second scanning direction on at least a portion of a weld bead formed along the first scanning direction by scanning the laser beam in a second scanning direction that intersects the scanning direction. This is a laser welding method for forming an enlarged portion of a bead.

The present invention also includes a first scanning unit that scans a laser beam in a first scanning direction along a welding locus for welding a plurality of superimposed members.
In a state where the laser beam is scanned in the first scanning direction, the laser beam is moved in a second scanning direction intersecting the first scanning direction by moving the laser beam relative to the member. Second scanning means for forming an enlarged portion of the weld bead expanded in the second scanning direction on at least a part of the weld bead formed along the first scanning direction by scanning The laser welding apparatus which has these.

  In the second aspect of the present invention, at least a part of a weld bead formed along a first scanning direction along a welding locus for welding a plurality of overlapped members intersects the first scanning direction. It is a welding member which has the enlarged part of the weld bead formed by expanding in the scanning direction.

  According to the present invention, at least a part of the weld bead formed along the first scanning direction along the welding trajectory is enlarged in the second scanning direction that intersects the first scanning direction. Since the portion is formed to increase the amount of melting of the welded member, it is possible to improve the welding strength at an arbitrary position of the welded portion and to prevent poor welding.

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
FIG. 1 is a schematic diagram showing a laser welding apparatus 100 according to an embodiment of the present invention, and FIG. 2 shows a drive shaft 20 constituting a first scanning unit provided in the optical scanner 10 and a second scanning unit. It is a schematic perspective view which shows the drive shaft 21 which comprises. FIG. 3 is a plan view showing the outer shape of the weld bead 35 formed along the C-shaped welding locus 27 by the laser welding method according to the present embodiment. 4A is an enlarged plan view showing the start end portion 36 of the weld bead formed in a substantially circular shape, and FIG. 4B shows the start end portion 36 of the weld bead formed in a linear shape. It is a top view which expands and shows. FIG. 5 is a plan view showing the outer shape of the weld bead 35 formed along the S-shaped welding locus 27. FIG. 6 is a plan view showing the outer shape of a weld bead 35 formed along a round-shaped welding locus 27.

  In this embodiment, the laser welding method of the present invention is applied to a laser welding method in which the steel plates 70 and 80 are welded by the laser welding apparatus 100 (see FIG. 1).

  Referring to FIGS. 1 to 6, the laser welding method will be outlined. A first scanning direction 27 (welding locus) for welding stacked steel plates 70 and 80 (corresponding to a plurality of members and metal plate materials). 27), the laser beam L is moved relative to the steel plates 70, 80 while scanning the laser beam L along the second scanning direction 28, which intersects the first scanning direction 27. An enlarged weld bead 39 enlarged in the second scanning direction 28 is formed on at least a part of the weld bead 35 formed along the first scanning direction 27 by scanning. The welding trajectory 27 includes a welding bead starting end portion 36 formed by scanning the laser beam L from the welding start point 25 and a welding bead end portion 37 formed by scanning the laser beam L up to the welding end point 26. It is a welding locus that does not overlap. Enlarged portions 39 are formed at the start end portion 36 and the end end portion 37 of the weld bead 35. The optical mirror 15 scans the laser beam L in the second scanning direction 28 while scanning the laser beam L in the first scanning direction 27. In this specification, the position at which laser welding is started is referred to as a welding start point 25, and the position at which laser welding is ended is referred to as a welding end point 26. Welding is performed by scanning the laser beam L along a welding locus 27 from the welding start point 25 to the welding end point 26. During the welding operation, irradiation is performed without controlling the output energy of the laser beam L. The direction and path in which the welding operation proceeds from the welding start point 25 to the welding end point 26 is a welding locus 27 (hereinafter also referred to as “first scanning direction 27”), and the scanning direction that intersects the welding locus 27 is the second. The scanning direction is 28. A scanning trajectory 31 is obtained by combining the scanning trajectories of the laser beam L along the first scanning direction 27 and the second scanning direction 28. The weld bead formed in the peripheral part of the welding start point 25 by scanning the laser beam L is used as the start end part 36 of the weld bead, and the weld bead formed in the peripheral part of the welding end point 26 is the terminal part 37 of the weld bead. (See FIG. 3). A weld bead is a weld mark formed by solidifying a part of a welded member melted by a laser beam. Details will be described below.

  Referring to FIG. 1, a laser welding apparatus 100 irradiates a laser beam L and an optical head 60 including an optical scanner 10 that adjusts a scanning direction, a robot hand 55 that moves the optical head 60, and a laser beam L. And a laser oscillator 50 for supply. Laser welding is performed by irradiating and scanning the laser beams L on the steel plates 70 and 80 arranged to be overlapped by the clamp means 90.

  The optical scanner 10 will be described with reference to FIG.

  The optical scanner 10 moves the optical mirror 15 that reflects the incident laser beam, the drive shaft 20 that moves the optical mirror 15 to scan the laser beam L along the first scanning direction 27, and the optical mirror 15. And a drive shaft 21 that scans the laser beam L in the second scanning direction 28. By simultaneously controlling both the drive shafts 20 and 21, for example, the laser beam L can be scanned along a curved welding locus.

  The drive shafts 20 and 21 can be driven and rotated (moved) at high speed by drive units 29 and 30 such as servo motors and galvano motors. The laser beam L can be scanned in the first scanning direction 27 by rotating the optical mirror 15 in the directions of arrows a and a ′ by the drive shaft 20. Scanning can be performed by rotating the optical mirror 15 in the directions of arrows b and b ′ by the drive shaft 21 and moving the laser beam L in the second scanning direction 28. Therefore, at the time of welding work, it is possible to scan by moving the laser beam L in the second scanning direction 28 while scanning the laser beam L in the first scanning direction 27 by the drive shafts 20 and 21. The first scanning unit 23 that scans the laser beam L in the first scanning direction 27 includes a drive unit 29, the optical mirror 15, and the drive shaft 20. The second scanning unit 24 that scans the laser beam L in the second scanning direction 28 includes a drive unit 30, an optical mirror 15, and a drive shaft 21. By controlling the amount of rotation of the drive shaft 21, the amplitude 32 of the enlargement unit 39 can be adjusted (see FIGS. 4A and 4B).

  The combinations of the drive shafts 20 and 21 and the movement of the laser beam L and the scanning direction are not particularly limited. For example, the driving shaft 21 can be rotated to scan the laser beam L in the first scanning direction 27 while the driving shaft 20 can be rotated to scan the laser beam L in the second scanning direction 28.

  Next, the laser welding method will be described.

  With reference to FIGS. 3 to 6, a weld bead 35 is formed along the welding locus 27 by scanning the laser beam L on the steel plate 70.

  First, immediately after irradiating the welding start point 25 with the laser beam L, the laser beam L is scanned in the second scanning direction 28 while scanning the laser beam L in the first scanning direction 27. At this time, the laser beam L is scanned a plurality of times in the second scanning direction 28. The weld bead starting portion 36 has a weld bead enlarged portion 39 enlarged in the second scanning direction 28 rather than a weld bead formed along the welding locus 27 (hereinafter, referred to as a “general portion 38”). (Hereinafter referred to as “enlarged portion 39”) is formed.

  Next, the steel plates 70 and 80 are welded by scanning the laser beam L along the welding locus 27 from the starting end portion 36 of the weld bead. As illustrated, for example, the laser beam L is scanned along a C-shaped (loop-shaped) welding locus 27.

  When the laser beam L has been scanned to the vicinity of the welding end point 26, the laser beam L is scanned in the first scanning direction 27, and the laser beam L is moved again in the second scanning direction 28 and scanned. Similarly to the start end portion 36 of the weld bead, an enlarged portion 39 can be formed at the end portion 37 of the weld bead. Subsequently, the laser beam L is scanned up to the welding end point 26 to complete the welding operation. As described above, the weld bead 35 having the enlarged portions 39 at the start / end portions 36 and 37 is formed on the steel plate 70. By forming the enlarged portion 39, the amount of melting the steel plate 70, that is, the welding amount can be increased.

  In laser welding, in order to improve the welding strength of a part of the welded part or to prevent poor welding between welding members, there is a method of increasing the amount of melting of the welding member by increasing the output energy of the laser beam. Conceivable. However, it is necessary to consume extra energy by increasing the output energy of the laser beam. Furthermore, since the output energy of the laser beam is controlled, there arises a problem that the welding operation becomes complicated.

  On the other hand, in this embodiment, since the welding amount can be increased by forming the enlarged portion 39, the welding strength between the welding members is improved without controlling the output energy of the laser beam. It is possible to prevent welding defects.

  With reference to FIGS. 4A and 4B, the enlargement unit 39 can change its shape by adjusting the amplitude 32 of the laser beam L in the second scanning direction 28. For example, the enlarged portion 39 having a substantially round shape can be formed by changing the amplitude 32 (see FIG. 4A). By making the amplitude 32 and the pitch 33 constant, a linearly-shaped enlarged portion 39 can be formed (see FIG. 4B).

  When forming the enlarged portion 39, the amount of heat applied to the enlarged portion 39 can be adjusted by increasing the moving speed in the second scanning direction 28 relative to the moving speed in the first scanning direction 27. . By changing the pitch 33, the amount of heat applied between the scanning trajectories 31 can be adjusted.

  At the start and end of welding, the output energy of the laser beam supplied from the laser oscillator becomes unstable. Therefore, there is a possibility that a decrease in welding strength or poor welding may occur in the vicinity of the welding start point and end point. Since the welding start point and end point are portions where stress is most easily concentrated when stress is applied from the outside, it is desirable that the welding start point and end point have a greater welding strength than other portions. Therefore, a method of controlling the output energy of the laser beam to prevent a decrease in welding strength in the vicinity of the welding start point and end point can be considered. In that case, it becomes necessary to provide control means to control the output energy of the laser beam, which complicates the welding operation.

  On the other hand, in the present embodiment, since the enlarged portion 39 is formed at the start and end portions 36 and 37 of the weld bead to increase the amount of melting of the weld member, the output energy of the laser beam is controlled. In addition, the welding strength at the periphery of the welding start point and end point can be improved.

  Generally, in laser welding, craters (dents) are generated at the welding start point and end point. For this reason, cracking of the welded member or poor welding may occur when the start and end portions 36 and 37 of the weld bead are overlapped and welded.

  As described above, in this embodiment, laser welding is performed along the C-shaped welding locus 27 where the start and end portions 36 and 37 of the weld beads do not overlap. Therefore, it is possible to prevent cracks and poor welding at the start and end portions 36 and 37 of the weld bead. Furthermore, since the area welded to the steel plates 70 and 80 can be increased as compared with the case where laser welding is performed linearly, the welding strength can be improved.

  Referring to FIGS. 5 and 6, laser welding is performed along a welding locus 27 of, for example, an S shape (see FIG. 5) or a round shape (see FIG. 6) in addition to the C shape. Can do. As in the case described above, it is possible to prevent cracking and poor welding and improve welding strength.

  As described above, in this embodiment, a part of the weld bead 35 formed along the first scanning direction 27 is enlarged in the second scanning direction 28 that intersects the first scanning direction 27. Since the amount of melting of the steel plate 70 is increased by forming the portion 39, the welding strength at an arbitrary position of the welding location is improved and the occurrence of poor welding is prevented without controlling the output energy of the laser beam. can do.

  Since laser welding is performed along a welding locus 27 (for example, a C shape, an S shape, or a round shape) where the start and end portions 36 and 37 of the weld bead do not overlap, the start and end portions 36 and 37 of the weld bead Cracks and poor welding can be prevented. Furthermore, since the area welded to the steel plates 70 and 80 can be increased as compared with the case where laser welding is performed linearly, the welding strength can be improved.

  Since the enlarged portion 39 is formed at the start and end portions 36 and 37 of the weld bead to increase the melting amount of the steel plate 70, the welding start point 25 and the welding end point 26 can be controlled without controlling the output energy of the laser beam. The welding strength in the peripheral part can be improved.

  The optical mirror 15 can scan the laser beam L in the first scanning direction 27 and move the laser beam L in the second scanning direction 28 at a high speed to form the enlarged portion 39.

  Without controlling the output energy of the laser beam L, the welding strength between the steel plates 70 and 80 can be improved.

  A steel plate 70 having an enlarged portion 39 formed in a part of the weld bead 35 formed along the first scanning direction 27 and enlarged in the second scanning direction 28 intersecting the first scanning direction 27; 80 can be formed.

  In the present embodiment, the welding locus 27 has a C-shape, an S-shape, or a round shape, but is not limited thereto, and is, for example, along a linear welding locus. Welding can be performed.

  The welding member is not limited to the metal plate members 70 and 80, and a member that can be welded by laser welding can be used.

(Second Embodiment)
FIG. 7 is a schematic perspective view showing the piezoelectric element 22 constituting the second scanning unit 24 provided in the optical scanner 10. Members that are the same as those shown in FIGS. 1 to 6 are given the same reference numerals, and descriptions thereof are partially omitted.

  In the present embodiment, the optical mirror 15 and the piezoelectric element 22 are used for the second scanning unit. By vibrating the piezoelectric element 22 in the c and c ′ directions, the optical mirror 15 is vibrated to scan the laser beam L in the second scanning direction 28.

  The type and form of the piezoelectric element 22 are not particularly limited. From the viewpoint of reducing the weight of the optical mirror 15, it is desirable that the piezoelectric element 22 be small and light. Further, the position where the piezoelectric element 22 is provided is preferably provided on the back surface of the optical mirror 15 so as not to prevent the incidence and reflection of the laser beam L, for example. Furthermore, the laser beam L can be scanned by using the drive units 29 and 30 and the drive shafts 20 and 21 together with the piezoelectric element 22.

  For the second scanning means 21, for example, a method of moving the steel plates 70 and 80 themselves and relatively scanning the laser beam L in the second scanning direction 28 can be used. In addition, for example, a method of vibrating the drive shafts 20 and 21 or a method of applying vibration to the optical mirror 15 by a method of rotating the optical mirror 15 at high speed can be used.

(Third embodiment)
FIGS. 8A and 8B are views each showing the outer shape of the weld bead 35 in a plane and showing the cross sections of the steel plates 70 and 80. FIG. 9 (A) shows a comparison in the case where the enlarged portion 39 is not formed in the portion 40 where the gap between the clamped steel plates is generated, and FIG. 9 (B) shows the portion where the gap is generated. 40 shows a case where the enlarged portion 39 is formed. Members that are common to the members shown in FIGS.

  The enlarged portion 39 can be provided in addition to the start and end portions 36 and 37 of the weld bead. For example, when a gap is generated between the steel plates 70 and 80 arranged in a clamped manner, the enlarged portion 39 can be formed in the portion 40 where the gap is generated in the steel plate 70 to prevent poor welding. Hereinafter, a gap generated between the steel plates 70 and 80 is referred to as a gap portion 41.

  With reference to FIG. 8 (A), when the gap 41 is generated between the steel plates 70 and 80, the enlarged portion 39 is formed in accordance with the portion 40 where the gap is generated. As described above, by forming the enlarged portion 39, the amount of melting of the steel plate 70, that is, the amount of welding can be increased, so that poor welding can be prevented.

  Referring to FIG. 8B, the steel plates 70 and 80 are arranged so that the height h of the gap gradually increases from the center line 42 of the steel plates 70 and 80 to both ends (left and right directions in the figure). Even in such a case, it is possible to prevent welding failure between the steel plates 70 and 80 by forming the enlarged portion 39 by changing the amplitude 32 as the height h of the gap portion gradually increases. it can.

  With reference to FIG. 9 (A), in comparison with the case where the enlarged portion 39 is not formed in the portion 40 where the gap is generated, the steel plate 43 melted by the laser beam L is insufficient with respect to the height h of the gap. Therefore, poor welding occurs between the steel plates 70 and 80.

  Referring to FIG. 9B, as shown in the present embodiment, when the enlarged portion 39 is formed in the portion 40 where the gap portion is generated, the amount of melting the steel plate 70 can be increased. , It is possible to prevent poor welding. Note that an arrow in FIG. 7B means scanning of the laser beam L in the second scanning direction 28.

  As described above, in the present embodiment, by forming the enlarged portion 39, it is possible to increase the amount of melting the steel plate 70 in the portion 40 where the gap is generated, and thus prevent welding failure from occurring. it can.

  Although the embodiment in which laser welding is performed along the linear welding locus 27 is shown, welding can also be performed along the above-described C-shaped, S-shaped, and round-shaped welding locus.

  It is possible to improve the welding strength by forming the enlarged portion 39 in addition to the portion 40 where the gap is generated.

(Fourth embodiment)
FIG. 10 is a schematic perspective view showing the steel plates 70 and 80 arranged with the gap portion height h gradually increased. The members common to those shown in FIGS. 1 to 9 are denoted by the same reference numerals, and the description thereof is partially omitted.

  In the present embodiment, the gap portions 41 are intentionally generated, and the steel plates 70 and 80 are arranged with the heights h of the gap portions gradually increased.

  Referring to FIG. 10, steel plates 70 and 80 are overlapped by gradually increasing the height h of the gap portion toward the right hand direction in the drawing by a clamping device (not shown). If the welding start point 25 is provided at a location where the height h of the gap is large, the steel plate 70 may be easily cracked. On the other hand, in the peripheral portion 45 of the contact portion 44 where the steel plates 70 and 80 are in contact with each other, the gap portion 41 is generated at a height that does not cause cracking even at the start of welding. Therefore, by providing the welding start point 25 in the peripheral part 45 of the contact location, it is possible to prevent cracks from occurring at the start of welding. The laser beam L is scanned along a welding locus 27 from the welding start point 25 toward the larger gap height h. Since the steel plate 70 melted by the laser beam L gradually melts the periphery from the side where the gap portion height h is small, welding can be performed without causing cracks even at locations where the gap portion height h is large. It can be carried out.

  As shown in the drawing, enlarged portions 39 are formed at the start and end portions 36 and 37 and the general portion 38 of the weld bead. Therefore, the welding strength at the periphery of the welding start point 25 and the welding end point 26 and at the general part 38 can be improved. Furthermore, since welding is performed along the C-shaped welding locus 27 where the start and end portions 36 and 37 of the weld bead do not overlap, it is possible to prevent cracks and poor welding and improve the welding strength.

  As described above, in the present embodiment, even when welding the steel plates 70 and 80 disposed with the height h of the gap portion gradually increased, the gap has a height within a range where cracks do not occur. A welding start point 25 is provided at a part where the part 41 is generated (peripheral part 44 of the contact part), and cracks are generated by performing welding along the welding locus 27 toward the larger height h of the gap. Without this, laser welding can be performed.

  The welding locus 27 may be other than the C-shape, and for example, welding can be performed along the aforementioned S-shape, round shape, or linear welding locus.

  The location where the enlarged portion 39 is formed is not particularly limited, and can be appropriately formed at a position where it is necessary to improve the welding strength or a position where poor welding is prevented.

FIG. 1 is a schematic view showing a laser welding apparatus according to an embodiment of the present invention. FIG. 2 is a schematic perspective view showing a drive shaft constituting the first scanning means and a drive shaft constituting the second scanning means provided in the optical scanner. It is a top view which shows the external shape of the weld bead formed along the C-shaped welding locus with the laser welding method which concerns on this embodiment. 4A is an enlarged plan view showing the starting end of the weld bead formed in a substantially circular shape, and FIG. 4B is an enlarged view of the starting end of the weld bead formed in a linear shape. FIG. It is a top view which shows the external shape of the weld bead formed along the S-shaped welding locus. It is a top view which shows the external shape of the weld bead formed along the welding locus | trajectory of a round shape. FIG. 7 is a schematic perspective view showing a piezoelectric element constituting the second scanning means provided in the optical scanner. FIGS. 8A and 8B are views each showing a profile of a weld bead in a plane and a cross section of a steel plate. FIG. 9A is a diagram showing a comparison when the enlarged portion is not formed in the portion where the gap is generated, and FIG. 9B is a case where the enlarged portion is formed in the portion where the gap is generated. FIG. FIG. 10 is a schematic perspective view showing the steel plates arranged with the gap portions gradually increased in height.

Explanation of symbols

10 Optical scanner,
15 optical mirror,
20, 21 drive shaft,
22 piezoelectric elements,
23 first scanning means,
24 second scanning means,
25 Welding start point,
26 Welding end point,
27 Welding locus (first scanning direction),
28 second scanning direction,
29, 30 drive unit,
31 Scanning trajectory,
32 amplitude,
33 pitch,
35 weld bead,
36 The beginning of the weld bead,
37 End of weld bead,
38 General Department,
39 Enlarged part,
40 The part where the gap occurs,
41 gap,
42 Centerline of steel plate,
43 Melted steel sheet,
44 contact points,
45 Periphery of the contact area,
50 laser oscillator,
55 Robot hand,
60 optical head,
70, 80 steel plate (multiple members, metal plate),
90 clamping means,
100 laser welding equipment,
L laser beam,
h Height of the gap.

Claims (10)

  While scanning a laser beam in a first scanning direction along a welding trajectory for welding a plurality of superposed members, the laser beam is moved relative to the member and intersects the first scanning direction. An enlarged portion of the weld bead expanded in the second scanning direction on at least a part of the weld bead formed along the first scanning direction by scanning the laser beam in the second scanning direction Laser welding method for forming   The welding trajectory is such that the start end of a weld bead formed by scanning the laser beam from a welding start point and the end of the weld bead formed by scanning the laser beam up to a welding end point do not overlap. The laser welding method according to claim 1, wherein the laser welding method is a locus.   The laser welding method according to claim 2, wherein the enlarged portion is formed at the start end portion and the end end portion of the weld bead.   4. The laser according to claim 1, wherein the laser beam is scanned in the second scanning direction by moving an optical mirror that scans the laser beam in the first scanning direction. 5. Welding method.   The laser welding method according to any one of claims 1 to 4, wherein irradiation is performed without controlling the output energy of the laser beam.   The laser welding method according to claim 2, wherein the welding locus has a C shape, an S shape, or a round shape.   The laser welding method according to any one of claims 1 to 6, wherein the member is a metal plate, and a position where the enlarged portion is formed is a portion where a gap is generated between the plates.   The member is a metal plate, and is overlapped by gradually increasing the gap between the two plate members from the contact point where one plate member contacts the other plate member, and is provided at the periphery of the contact point. The laser welding method according to claim 1, wherein the laser welding method has a welding locus from the welding start point toward the larger gap. First scanning means for scanning a laser beam in a first scanning direction along a welding locus for welding a plurality of superimposed members;
In a state where the laser beam is scanned in the first scanning direction, the laser beam is moved in a second scanning direction intersecting the first scanning direction by moving the laser beam relative to the member. Second scanning means for forming an enlarged portion of the weld bead expanded in the second scanning direction on at least a part of the weld bead formed along the first scanning direction by scanning A laser welding apparatus.   A weld bead formed along a first scanning direction along a welding trajectory for welding a plurality of superposed members is expanded in a second scanning direction that intersects the first scanning direction. A welded member having an enlarged portion of a weld bead formed.

Images