JP5227142B2 - Laser welding method - Google Patents

Description

  The present invention relates to a laser welding method.

  Non-penetrating type (keyhole type) laser welding, in which metal materials are overlapped and irradiated with a laser beam to melt one metal material and a part of the other metal material, is welded. is there. In this laser welding, since the bead is exposed only on the surface of one metal material irradiated with the laser beam, the appearance of the other metal material is kept good. However, in non-penetrating laser welding, a non-metallic substance (slag) generated by laser beam irradiation inside the welded portion is not released to the outside, so it remains in the welded portion or weld distortion ( There is a problem that the deformation of the metal plate becomes large.

Thus, for example, in the welding method described in Patent Document 1, two metal plates are overlapped and irradiated with a laser beam, and the two metal materials are penetrated and welded (see, for example, Patent Document 1). In this penetration type laser welding, the slag is easily released to the outside of the metal material during welding, and the soundness of the welded portion is maintained. Moreover, since a welded part penetrates two metal plates, welding distortion is also suppressed.
JP 2002-144063 A

  However, in the conventional penetration type laser welding, beads are exposed on both surfaces of the joined body after joining. For this reason, in order to use the workpiece subjected to laser welding as an outer plate of a railway vehicle structure, a device for maintaining a good external appearance is required.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a laser welding method capable of improving the appearance of a workpiece in penetration welding.

  In order to solve the above-described problems, a laser welding method according to the present invention is a laser welding method for forming a through-weld portion on a workpiece by irradiation with a laser beam, and corresponds to a formation planned position of the through-weld portion. A process of superimposing the other workpiece on one workpiece having the provided groove, and irradiating the overlap portion of the workpiece along the planned formation position with a laser beam, and a through-welding portion at the bottom of the groove And a step of forming a brazing portion on the surface of the through weld so as to fill the groove.

  In this laser welding method, a through-weld is formed at the bottom of the groove by forming a groove in one workpiece. And a brazing part is formed in the surface of a penetration welding part so that a groove part may be filled up. In the workpiece after welding, at least one side of the penetration welded portion is not exposed on the surface by the brazing portion, so that the appearance of the workpiece is improved. Further, in this laser welding method, since a through-weld portion that penetrates the workpiece is formed during welding, problems of slag and welding distortion can be reduced.

  Further, it is preferable to irradiate the overlapped portion from one workpiece side with a laser beam. In this case, the alignment at the time of laser beam irradiation is facilitated by targeting the groove formed in one of the workpieces.

  The other workpiece is also provided with a groove at a position where the through-weld is to be formed, and is formed on the surface of the through-weld so as to fill the groove of one workpiece and the groove of the other workpiece, respectively. It is preferable to form a brazing part. In this case, in the workpiece after welding, both sides of the through-welded portion are not exposed to the surface by the brazing portion, so that the appearance of the workpiece is further improved.

  In addition, after forming the brazing portion so as to protrude from the surface of the workpiece, polishing the protruding portion of the brazing portion so that the surface of the brazing portion and the surface of the workpiece are flush with each other. It is preferable to flatten. In this case, since the surface of the brazing portion and the surface of the workpiece are more reliably flattened, the appearance of the workpiece is further improved.

  Moreover, it is preferable that the width | variety of the bottom part in a groove part is formed larger than the width | variety of the penetration welding part which it is going to form. In this case, the above method can also be applied to the case where the width of the through-welded portion is widened or the spot-like through-welded portion is formed in a staggered manner.

  Moreover, it is preferable that a groove part is a cross-sectional rectangular shape. In this case, it is easy to ensure the area of the bottom of the groove, so that the laser beam can be easily aligned.

  Moreover, it is preferable that a groove part is cross-sectional arc shape. In this case, stress concentration on the through-weld formed at the bottom of the groove can be reduced.

  Moreover, it is preferable that a groove part is a cross-sectional triangle shape. In this case, the groove can be easily formed.

  Moreover, it is preferable that the pigment | dye component is added to the brazing material. In this case, the appearance of the workpiece can be improved.

  The brazing material is preferably a material different from the workpiece. In this case, the appearance of the workpiece can be improved.

  ADVANTAGE OF THE INVENTION According to this invention, the external appearance of the workpiece in penetration welding can be made favorable.

  Hereinafter, preferred embodiments of a laser welding method according to the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing an outline of a laser welding method according to an embodiment of the present invention. As shown in FIG. 1, this laser welding method is for lap welding two stacked metal plates 10 a and 10 b (hereinafter referred to as “workpiece (workpiece) W”). In the present embodiment, through welding is performed by irradiating the workpiece W with the laser beam L1 from the direction of the metal plate 10a. The metal plates 10a and 10b are, for example, stainless steel.

  Here, in the metal plate 10a to which the laser beam L1 is directly irradiated, a groove portion (concave portion) G is provided corresponding to a position where the penetration weld portion 24 is to be formed. Specifically, the groove part G will be described with reference to FIG. 2 is a cross-sectional view taken along line II-II in FIG. As shown in the figure, the groove part G has a rectangular cross section, and the width of the bottom part Ga of the groove part G is about twice as large as the width (broken line part) of the through welded part 24 to be formed. Is formed. The depth of the groove part G is about 1/3 of the thickness of the metal plate 10a. In addition, the groove part G becomes the welding scheduled area P.

  Returning to FIG. 1, the laser welding method described above is executed using a laser welding apparatus 20. The laser welding apparatus 20 includes a welding laser 21 that irradiates a workpiece W with a laser beam L1 to form a through-weld portion 24, a brazing laser 22 that irradiates a laser beam L2 at a subsequent stage of the welding laser 21, and a brazing laser. The material supply part 23 is comprised.

  The welding laser 21 irradiates a laser beam L1 from a laser oscillation part (not shown) toward a welding planned region P (overlapping portion) of the metal plate 10a. The welding laser 21 causes the laser head to emit a laser beam L1 that can perform through welding on the workpiece W. The laser beam L1 emitted from the welding laser 21 is, for example, a YAG laser having a wavelength of 1.06 μm and an output of about 4.0 kW.

  The brazing laser 22 irradiates the laser beam L2 toward the tip of the brazing material R supplied from the brazing material supply unit 23 so as to follow the laser beam L1 emitted from the welding laser 21. The brazing laser 22 irradiates a laser beam L2 (L1> L2) having a smaller output than the laser beam L1 emitted from the welding laser 21.

  The brazing material supply unit 23 is a portion that supplies brazing material (hard brazing) R toward the irradiation position of the laser beam L2 of the brazing laser 22. As the brazing material R, for example, copper, brass or the like, which is a different metal from the workpiece W (stainless steel), is used. The brazing material supply unit 23 is disposed on the front side with respect to the traveling direction of the brazing laser 22 and supplies the brazing material R in a state of being inclined with respect to the surface of the workpiece W.

  As shown in FIG. 1, the laser welding apparatus 20 includes a photo sensor 25, a monitor 26, and a component for inspecting the welding state of the through-weld portion 24 formed using the welding laser 21. It has. Here, as a welding state, it is inspected whether or not the penetration welded portion 24 has correctly penetrated the workpiece W.

  The photo sensor 25 is provided, for example, inside the welding laser 21. The photosensor 25 detects a part of the plasma generated at the irradiation position of the laser beam L on the surface Wa of the workpiece W. The photo sensor 25 outputs a detection signal corresponding to the light intensity of the plasma to the monitor 26.

  The monitor 26 displays the welding state as a waveform pattern. Upon receiving the detection signal output from the photosensor 25, the monitor 26 generates a waveform pattern with respect to the time axis of the detection signal. The monitor 26 displays the generated waveform pattern on the display. A specific example of the waveform pattern displayed on the display will be described later.

  A laser welding method according to this embodiment will be described with reference to FIGS. 1 and 2. First, the workpiece W is set on a predetermined surface plate so that the groove portion G is on the upper side. Further, the welding laser 21 is set so that the irradiation position of the laser beam L1 of the welding laser 21 is located at the start point of the groove G which is the welding scheduled region P. At this time, the laser beam L1 is set so that the irradiation position of the laser beam L1 is substantially at the center of the groove G as shown in FIG.

  Next, the welding laser 21 is moved in the direction of arrow A in FIG. 1 while irradiating the laser beam L1 at a predetermined speed. Thereby, in the bottom part Ga of the groove part G, the penetration welding part 24 which penetrates the metal plates 10a and 10b is sequentially formed.

  Further, following the welding laser 21, the laser beam L2 is emitted from the brazing laser 22. The brazing material R is supplied from the brazing material supply portion 23 to the irradiation position of the laser beam L2, and the groove portion G is filled with the molten brazing material R, so that the brazing portion 27 is sequentially formed on the surface 24a of the through-welding portion 24. It is formed.

  When the brazing laser 22 reaches the end point of the planned welding region P, the continuous through-welding portion 24 and the brazing portion 27 in which the groove portion G is filled with the brazing material R are formed, and the welding of the workpiece W is completed. In the state immediately after the welding is finished, the brazing portion 27 covering the surface 24a of the through-welding portion 24 is formed so as to protrude from the surface Wa of the metal plate 10a as shown in FIG. Therefore, for example, by polishing the protruding portion 27a of the brazing portion 27 protruding from the surface Wa of the metal plate 10a with a grinder to which a fine grindstone having a particle size of about # 50 is attached, FIG. As described above, the surface 27b of the brazing portion 27 and the surface Wa of the workpiece W are flattened so as to be flush with each other.

  Further, the laser welding apparatus 20 displays a waveform pattern indicating a welding state on the monitor 26 based on the light intensity of the plasma detected by the photosensor 25 during the irradiation of the laser beam L1. FIG. 4 shows a waveform pattern P1 of the output signal from the photosensor 25 when the through welding is normally completed, and a waveform pattern P2 of the output signal from the photosensor 25 when the penetration is not performed in the middle of the welding. FIG. As shown in FIG. 4, when the through welding is normally completed, the waveform pattern P1 is stable at a low level of about the level F1.

  On the other hand, when the weld becomes non-penetrating from the middle, for example, the reflected light intensity suddenly increases from time t1 to the vicinity of level F2, and the reflected light intensity is more unstable than the waveform pattern P1 with respect to the time axis. The waveform pattern P2. Therefore, an operator who performs welding can determine whether or not the through-welded portion 24 is normally formed by monitoring the behavior of the waveform pattern displayed on the monitor 26. Furthermore, by visually observing the through-welding portion 24 of the actual workpiece W, it is possible to confirm whether or not the welded state is possible.

  As described above, in the laser welding method according to this embodiment, by forming the groove portion G in one metal plate 10a, the through-welding portion 24 is formed in the bottom portion Ga of the groove portion G. And the brazing part 27 is formed in the surface 24a of the penetration welding part 24 so that the groove part G may be filled. In the workpiece W after welding, at least one side of the through-welding portion 24 is not exposed to the surface Wa by the brazing portion 27, so that the appearance of the workpiece W is good. Moreover, in this laser welding method, since the through-weld portion 24 that penetrates the workpiece W is formed during welding, problems of slag and welding distortion that occur in non-through-welding can be reduced.

  Further, the brazing portion 27 is formed so as to protrude from the surface Wa of the metal plate 10a, and the protruding portion 27a is polished by a grinder or the like so that the surface 27b of the brazing portion 27 and the surface Wa of the metal plate 10a face each other. Make it one. Thereby, the surface 27b of the brazing portion 27 and the surface Wa of the metal plate 10a are surely flattened, so that the appearance of the workpiece W is further improved.

  Further, in this laser welding method, the laser beam L1 can be easily aligned by irradiating the laser beam L1 with a target having a rectangular section G in which the area of the bottom Ga is sufficiently secured. Further, since copper or brass, which is a different kind of metal from the stainless steel metal plates 10a and 10b, is used as the brazing material R, the brazing portion 27 is colored with respect to the metal plates 10a and 10b. Thereby, the external appearance of the workpiece | work W becomes a better thing.

  The present invention is not limited to the above embodiment. For example, in the above embodiment, the groove portion G is provided on one metal plate 10a. However, as shown in FIG. 5, the metal plate 10b is also provided with a groove portion G at a position facing the groove portion G of the metal plate 10a. After forming the welded portion 28, the brazed portions 29 may be formed on the surfaces 28a and 28b of the through welded portion 28 so as to fill the two groove portions G and G, respectively. In this case, in the workpiece W after welding, both sides of the through-welded portion 28 are not exposed to the surface Wa by the brazing portion 29, so that the appearance of the workpiece W is further improved.

  Moreover, in the said embodiment, although continuously irradiating the laser beam L1 and forming the continuous penetration welding part 24, said laser welding method may be applied to spot welding. FIG. 6 is a perspective view of a workpiece in spot welding. As shown in FIG. 6, for example, a groove portion G having a rectangular section having a size about four times larger than the width of the through spot weld portion 30 to be formed is provided, and a bottom portion Ga of the groove portion G has, for example, a staggered through spot weld portion. After forming 30, the brazing portions 31 may be formed on the surface 30a of the spot welded portion 30 so as to fill the groove portion G, respectively. Even in this case, in the workpiece W after welding, at least one side of the spot welded portion 30 is not exposed to the surface Wa by the brazing portion 31, so that the appearance of the workpiece W is improved.

  Moreover, in the said embodiment, although the groove part G was made into the rectangular cross section, the shape of the groove part G is not limited to this. For example, as shown to Fig.7 (a), a cross-sectional trapezoid shape may be sufficient. In this case, alignment of the laser beam L1 can be easily performed, and stress concentration on the formed through-weld portion 24 can be reduced. Moreover, as shown in FIG.7 (b), a cross-sectional arc shape may be sufficient. In this case, since the bottom Ga of the groove G is a curved surface, the stress concentration on the formed through-weld 24 can be further relaxed. Furthermore, as shown in FIG.7 (c), a cross-sectional triangle shape may be sufficient. In this case, the groove portion G can be formed more easily than the above shape.

  Moreover, in the said embodiment, after forming the brazing part 27 so that it may protrude rather than the surface Wa of the metal plate 10a, the protrusion part 27a is grind | polished with a grinder, and the surface 27b of the brazing part 27 is planarized. However, the brazing material R is appropriately supplied so that the protruding portion 27a of the brazing portion 27 is smaller than the state shown in FIG. 4A, and polishing of the protruding portion 27a after the formation of the brazing portion 27 is omitted. Also good. In this case, the process can be simplified.

  In addition to the above embodiment, a pigment component may be added to the brazing material R. As the pigment component, for example, copper or aluminum is used. In this case, since the brazing portion 27 can be colored in a desired color with respect to the metal plates 10a and 10b, the appearance of the workpiece W becomes better.

It is a figure which shows the outline | summary of the laser welding method which concerns on one Embodiment of this invention. It is the II-II sectional view taken on the line in FIG. It is the III-III sectional view taken on the line in FIG. It is a figure which shows the waveform pattern of the output signal from the photosensor when penetration welding is normally completed, and the waveform pattern of the output signal from the photosensor when non-penetration occurs in the middle of welding. It is sectional drawing of the penetration weld part which concerns on a modification. It is a perspective view of the workpiece | work in spot welding. It is a figure which shows the groove part which concerns on a modification.

Explanation of symbols

  10a, 10b ... metal plate (workpiece), 24, 28, 30 ... penetration weld, 24a, 28a, 28b, 30a ... surface of penetration weld, 27, 29, 31 ... brazing part, 27b ... brazing Surface of G part, G ... groove part, Ga ... bottom part, L1 ... laser beam, R ... brazing material, W ... work, Wa ... surface of work (metal plate).

Claims (10)

A laser welding method for forming a through-weld portion in a workpiece by laser beam irradiation,
Superimposing the other workpiece on one workpiece having a groove provided corresponding to the formation planned position of the through weld, and
Irradiating the overlapped portion of the workpiece along the planned formation position with the laser beam, and forming the through-weld at the bottom of the groove; and
Forming a brazed portion on the surface of the through weld so as to fill the groove,
A laser welding method comprising:   The laser welding method according to claim 1, wherein the laser beam is irradiated to the overlapped portion from the one workpiece side. The other workpiece is also provided with a groove at a position where the through weld is to be formed,
3. The laser according to claim 1, wherein a brazing portion is formed on a surface of the through-welding portion so as to fill the groove portion of the one workpiece and the groove portion of the other workpiece. Welding method.   After forming the brazing portion so as to protrude from the surface of the workpiece, the protruding portion of the brazing portion is polished so that the surface of the brazing portion and the surface of the workpiece are flush with each other. The laser welding method according to claim 1, wherein flattening is performed so that   The laser welding method according to any one of claims 1 to 4, wherein a width of the bottom portion in the groove portion is formed to be larger than a width of a through-weld portion to be formed.   The laser welding method according to claim 1, wherein the groove has a rectangular cross section.   The laser welding method according to claim 1, wherein the groove has a circular arc shape in cross section.   The laser welding method according to claim 1, wherein the groove has a triangular cross section.   The laser welding method according to claim 1, wherein a pigment component is added to the brazing material.   The laser welding method according to any one of claims 1 to 8, wherein the brazing material is a material different from the workpiece.

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