JP2018001191A - Spot welding method and welded product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spot welding method capable of performing spot welding with restrained heat deformation even when a stacking thickness of a plurality of plate-like works is large, as well as a welded product.SOLUTION: Provided is a spot welding method for performing welding by stacking a plurality of plate-like works. Upper-side works W2 and UW having small-diameter through-holes 3A and 3B are stacked on a lower-side work W1, and spot welding is performed by emitting a laser beam LB with a focal position adjusted to a vicinity of a joint part 5 between an upper surface of the lower-side work W1 and an inner peripheral surface of the small-diameter through-hole 3A in the upper-side work W2.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a spot welding method in which a plurality of plate-like workpieces are overlapped and spot welding is performed by laser welding, and a welded product in which spot welding is performed. More specifically, after laminating a plurality of plate-shaped workpieces in which small-diameter through holes have been formed in advance on the lower workpiece, laser beams are obliquely irradiated into the small-diameter through-holes, The present invention relates to a spot welding method and a welded product for performing welding using melting of a workpiece by irradiation and reflected light of a laser beam in a small-diameter through hole.

  When laser welding a plurality of plate materials, depending on the shape of the welded joint, for example, a plate-like workpiece is abutted, a butt joint that performs laser welding of this abutting portion, or a plurality of plate materials are overlapped, There are lap joints for laser welding the workpiece and the lower workpiece. In the case of the above-mentioned lap joint, spot welding is performed (see, for example, Patent Documents 1 and 2).

JP 2007-222937 A JP 56-80381 A

  In FIG. 8 in Patent Document 1, an upper plate in which small-diameter through holes are formed in advance is overlapped on the lower plate. And it describes that spot welding is performed by irradiating a laser beam with a focal position set at a position above the through hole in the upper plate. Moreover, in FIG. 1 of Patent Document 1, for example, when the plate thickness is 1 mm, an upper plate in which a concave hole having a diameter of about 2 to 2.5 mm and a depth of about 0.2 to 0.5 mm is formed in advance. Is described in that spot welding is performed by irradiating the bottom surface of the concave hole with laser light.

  Patent Document 2 describes that spot welding is performed by irradiating a laser beam to a portion where a copper or copper alloy plate is overlaid on a stainless steel member and a titanium thin plate is overlaid on the copper plate.

  By the way, when spot welding is performed by superimposing a plurality of metal plates, for example, when spot welding of a steel plate is performed using a laser beam oscillated from a laser oscillator with an output of 4 kW, the welding depth is about 6 mm. is there. Therefore, spot welding becomes difficult when the overlapping thickness of a plurality of plate-like workpieces is 6 mm or more. Here, it is also possible to perform spot welding with deeper penetration by increasing the output of the laser oscillator. However, in this case, there is a problem that the equipment cost becomes expensive.

  By the way, as shown in FIG. 1, a plurality of workpieces W1 and W2 having no through-holes are superimposed on a lower plate-like workpiece LW. When spot welding is performed by irradiating laser light (not shown) from the uppermost workpiece UW side, a deep penetration portion 1 for integrally welding the workpieces UW, W2, W1, and LW is formed. . In this case, since the penetration portion 1 is penetration from the upper workpiece UW to the lower workpiece LW, the output of the laser oscillator increases in accordance with the penetration depth. In addition, when the laser output is 4 kW, the depth of the penetration portion 1 is about 6 mm.

  As described above, when the deep penetration portion 1 is formed, there is a problem that the capacity of the penetration portion 1 increases and the surrounding thermal deformation increases.

  The present invention has been made in view of the above-described problems, and is a spot welding method in which a plurality of plate-like workpieces are overlapped and welded, and on the lower workpiece, the same diameter as the plate thickness or An upper work having a small diameter through hole having a thickness equal to or less than the plate thickness is overlapped, and welding is performed by irradiating the upper surface of the lower work with a laser beam having a smaller diameter than the small diameter through hole.

  Also, a spot welding method in which a plurality of plate-like workpieces are overlapped and welded, and an upper workpiece having a small-diameter through hole having the same diameter as the plate thickness or less than the plate thickness is stacked on the lower workpiece. In addition, welding is performed by irradiating a laser beam having a focal position in the vicinity of the joint between the upper surface of the lower workpiece and the inner peripheral surface of the small-diameter through hole in the upper workpiece.

  Further, in the spot welding method, a plurality of upper workpieces each having a small-diameter through hole are overlapped, and laser light is irradiated from a direction inclined with respect to the axis of the small-diameter through-hole, thereby laser in the small-diameter through-hole. The reflected light of light is applied to the inner peripheral surface of the small diameter through hole, and the inner peripheral surface of the small diameter through hole is melted and welded.

Further, a spot welding method for performing spot welding by stacking a plurality of plate-like workpieces,
(A) forming a through-hole having the same diameter or a small diameter in each upper work as a thickness dimension when the upper work is overlaid on a plurality of upper works to be overlaid on the lower work;
(B) A step of superimposing each upper work on the lower work in a state where the through holes are combined.
(C) a step of irradiating the upper surface of the lower workpiece with laser light in a state inclined with respect to the axis of the through hole;
(D) a step of melting and welding the inner peripheral surface of each through-hole by reflected light of a laser beam on the inner peripheral surface of the through-hole in each upper work;
Each process is provided.

  Further, in the spot welding method, the focal position of the laser beam is matched with the vicinity of the joint between the upper surface of the lower workpiece and the inner peripheral surface of the through hole in the upper workpiece on the lower workpiece.

  Further, in the spot welding method, a hole processing for weight reduction is performed in advance on a workpiece that is overlapped between the lower workpiece and the uppermost workpiece.

  Further, it is a spot welding method in which a plurality of plate-like workpieces are overlapped and laser welding is performed, and when a laser beam is irradiated on a curved line such as a circle around a spot welding point, the amount of heat stored in the workpiece is reduced. In order to suppress this, the laser beam output is reduced stepwise or continuously as the welding progresses from the welding start position to the welding end position.

  Also, a welded product comprising a plurality of plate-like upper workpieces stacked on a plate-like lower workpiece, the diameter of the welded portion obtained by spot welding the plurality of upper workpieces to the lower workpiece with laser light However, it is the same diameter as the overlap thickness of the plurality of upper workpieces or smaller than the overlap thickness.

  Also, a welded product comprising a plurality of plate-like upper workpieces stacked on a plate-like lower workpiece, comprising a melted and solidified metal inside each through hole formed in each upper workpiece. .

  Further, in the welded product, the workpiece overlapped between the lower workpiece and the uppermost workpiece is provided with a hole for weight reduction.

  According to the present invention, an upper work having a small-diameter through hole is overlaid on a lower work, and a laser is formed in the vicinity of a joint between the upper surface of the lower work and the inner peripheral surface of the through hole in the upper work. Spot welding is performed by irradiating light. Therefore, the incident energy is small, and the depth of the penetration portion can be set to a depth corresponding to the small diameter through hole. Therefore, spot welding of a plurality of plate-like workpieces can be performed with less thermal deformation.

It is explanatory drawing at the time of laminating | stacking a several sheet material and irradiating a laser beam in the state which does not form a small diameter through-hole beforehand, and performing spot welding. It is explanatory drawing of the spot welding method which concerns on embodiment of this invention. It is explanatory drawing of 2nd Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Components having the same functions as those illustrated in FIG. 1 are denoted by the same reference numerals.

  Referring to FIG. 2A, a plurality of workpieces W1, W2, and UW are overlapped from below on a thick plate-like workpiece LW on the lower side. In the stacked workpieces W1, W2, and UW, the lower workpiece is formed as a thinner workpiece. The upper workpiece UW and the lower workpiece W2 are formed with through holes 3A and 3B having a small diameter (about 1 mm) equal to or less than the plate thickness. The through holes 3A and 3B are aligned in the vertical direction. is there.

  In the above configuration, the vicinity of the joint 5 between the upper surface of the lower work W1 not provided with the through hole and the inner peripheral surface of the through hole 3A in the work W2 on the work W1, preferably the lower work W1. The laser beam LB having the focal position on the upper surface is irradiated from a direction inclined with respect to the axis of the through holes 3A and 3B.

  As described above, when the upper surface of the workpiece W1 is irradiated with the laser beam LB, the portion irradiated with the laser beam LB is heated and melted. And the circumference | surroundings of the irradiation position of the laser beam LB are also fuse | melted by heat conduction. A part of the laser beam LB is reflected and irradiates the inner peripheral surfaces of the through holes 3A and 3B. Therefore, the inner peripheral surfaces of the through holes 3A and 3B are heated and melted.

  The beam diameter of the laser beam LB is smaller than the through holes 3A and 3B. Therefore, the laser beam LB can be emitted deeply into the through holes 3A and 3B.

  As described above, the focal position is set near the joint 5 between the through hole 3A and the upper surface of the work W1 in the workpiece W2, that is, near the bottom of the through hole 3A, and the laser beam LB is directed to the axis of the through hole 3A. When obliquely irradiated, the portion irradiated with the laser beam LB is melted. And reflected light is irradiated with respect to the internal peripheral surface in through-hole 3A, 3B of workpiece | work W2, UW, and reflection of the laser beam LB is repeated in an internal peripheral surface. Therefore, the inner peripheral surfaces of the through holes 3A and 3B are heated and melted by being irradiated with the reflected light of the laser beam LB and by heat conduction from the portion melted by the irradiation of the laser beam LB.

  Therefore, molten metal accumulates at the bottom of the through holes 3A and 3B. That is, the part corresponding to the through hole 3A of the workpiece W1 is melted by heat conduction or the like, and the vicinity of the upper surface of the lower workpiece LW is melted. Further, the reflection of the laser beam LB is repeated in the through holes 3A and 3B of the workpieces W2 and UW, and the heat conduction from the molten metal accumulated in the through holes 3A and 3B causes the through holes 3A of the workpieces W2 and UW. , 3B inner surface is melted.

  As described above, through-holes 3A and 3B having the same diameter as the plate thickness or smaller than the plate thickness are formed in advance on the workpieces W2 and UW, and the through-holes 3A and 3B are overlapped with each other, near the bottom of the through-hole. By performing spot welding by adjusting the focal position, spot welding can be easily performed even when the overlapped workpiece has a large overlap thickness. In this case, since the inner peripheral surface of the through hole is melted, the capacity of the molten metal can be suppressed, and the diameter of the penetration portion 1 can be made smaller than that when no through hole is formed. Therefore, thermal deformation can be suppressed. In addition, after the spot welding is finished, the inner peripheral surfaces of the through holes 3A and 3B are melted and solidified. Accordingly, the through holes 3A and 3B are filled with molten and solidified metal.

  By the way, in the said description, the case where spot welding was performed, without forming a through-hole in the workpiece | work W1 was demonstrated. However, a through hole may be formed in advance in the workpiece W1. Moreover, in the said description, the case where 3 sheets of the workpiece | work W1, W2, UW were piled up on the lower workpiece | work LW was demonstrated. However, the number of workpieces to be stacked on the lower workpiece LW may be one, and the number of workpieces to be stacked may be arbitrary.

  Further, as described above, when spot welding is performed by irradiating the laser beam LB into the through holes 3A and 3B of the workpieces W2 and UW, the irradiation position of the laser beam LB may be moved in the vertical direction. .

  In the above description, it has been described that the diameters of the through holes 3A and 3B formed in the workpieces W2 and UW are the same as or less than the plate thickness. However, when a plurality of thin workpieces are overlapped thickly, the diameters of the through holes 3A and 3B can be set to be equal to or greater than the plate thickness. In this case, in order to utilize the repetition of reflection of the laser beam LB in the through holes 3A and 3B, the diameter of the through holes 3A and 3B is smaller than the thickness dimension when a plurality of workpieces are overlapped ( About 1 mm).

  That is, when the depth Lmm of the through hole when the workpieces are overlapped, the irradiation angle θ of the laser beam, and the diameter of the through hole are Dmm, the relationship of D = f (L, θ) may be maintained. is there.

  In the case described above, through holes 3A and 3B having a diameter smaller than the thickness H when the upper workpieces W2 and UW are stacked on the plurality of upper workpieces W2 and UW to be overlaid on the lower workpiece LW are provided for each upper workpiece. W2 and UW are formed. Then, the upper workpieces W2 and UW are overlaid on the lower workpiece LW so that the through holes 3A and 3B are aligned. Thereafter, in the vicinity of the joint 5 between the upper surface of the lower work (in this case, the work W1) and the inner peripheral surface of the through hole 3A in the upper work W2 on the lower work W1, preferably the lower work The laser beam LB is irradiated on the upper surface of W1 in a state inclined with respect to the axial centers of the through holes 3A and 3B. Then, as described above, the inner peripheral surfaces of the through holes 3A and 3B are melted and welded by the reflected light of the laser beam LB on the inner peripheral surfaces of the through holes 3A and 3B in the upper workpieces W2 and UW. Is.

  At this time, the focal position of the laser beam LB is the vicinity of the joint 5 between the upper surface of the lower workpiece W1 and the inner peripheral surface of the through hole 3A in the upper workpiece W2 on the lower workpiece W1 as described above. To match.

  The focal position of the laser beam LB may be near the lower portion of the inner peripheral surface of the through hole 3A. Further, when the laser beam LB is irradiated into the through holes 3A and 3B, the irradiation direction and the irradiation angle may be variously changed.

  By the way, when the plurality of workpieces LW, W1, W2, and UW are overlapped and spot-welded as described above, the workpieces W1 and W2 that are overlapped between the lower workpiece LW and the uppermost workpiece UW are lightweight. It is desirable to perform the hole processing 7 in order to make it easier.

  As described above, when a plurality of workpieces W2 and UW to be overlapped are previously formed with small diameter through holes 3A and 3B, and laser beam LB is obliquely irradiated into the through holes 3A and 3B to perform spot welding, As shown in FIG. 2 (B), a welded product comprising a plurality of plate-like upper workpieces W1, W2, UW stacked on a plate-like lower workpiece LW, wherein the upper workpieces W1, W2, The welded product 1 has a smaller diameter than the overlapped dimension of UW, in which the diameter of the welded portion 1 obtained by spot welding the upper workpieces W1, W2, and UW to the lower workpiece LW with a laser beam is reduced. Therefore, it becomes a welded product in which thermal deformation is suppressed.

  FIG. 3 conceptually shows the second embodiment of the present invention. In the second embodiment, a spot welding method in which a plurality of plate-like workpieces are overlapped to perform laser welding is shown. In this method, spot welding is performed by irradiating a laser beam LB around a spot welding point S to a small circular curve having a diameter of about 2 mm, for example, to perform laser welding. At this time, the laser beam LB is irradiated while moving in the arrow A direction from the welding start position a.

  When spot welding is performed by irradiating the laser beam LB in a small circle shape as described above, heat is gradually stored in the workpiece to be spot welded and the penetration depth varies. Therefore, laser welding is performed with a large output of 2800 W, for example, up to about the half-circumferential position b of the small circular portion. Then, laser welding is performed by controlling the output to 2700 W, for example, up to about 3/4 circumference position c. Furthermore, the output is further reduced to the welding end point d close to the welding start position a, and laser welding is performed with an output of 2300 W, for example.

  That is, when the laser beam LB is irradiated around the spot welding point S in a small circle shape, the laser beam LB is progressed from the welding start position a to the welding end point d in order to suppress the amount of heat stored in the workpiece. Is reduced stepwise or continuously. Then, the laser welding is finished without overlapping the welding start position a and the welding end position d.

  When spot welding is performed by irradiating the laser beam LB around the spot welding point S in a small circle shape and performing laser welding, as described above, the laser output is controlled stepwise or gradually and welding is started. By ending without overlapping the position a and the welding end point position d, the heat storage amount can be suppressed and welding can be performed with a substantially constant penetration depth. At this time, the spot welding point S is melted by heat conduction from the surroundings, and welding is performed on the inner side of the small circular laser irradiation position. That is, spot welding having a small circular diameter can be performed.

1 Penetration 3A, 3B Through-hole 5 Joint

Claims (10)

  It is a spot welding method in which a plurality of plate-like workpieces are overlapped and welded, and an upper workpiece having a small-diameter through hole having the same diameter as the plate thickness or less than the plate thickness is superimposed on the lower workpiece, A spot welding method, wherein welding is performed by irradiating an upper surface of the lower workpiece with a laser beam having a diameter smaller than that of the small diameter through hole.   It is a spot welding method in which a plurality of plate-like workpieces are overlapped and welded, and an upper workpiece having a small-diameter through hole having the same diameter as the plate thickness or less than the plate thickness is superimposed on the lower workpiece, A spot welding method, wherein welding is performed by irradiating a laser beam having a focal position in the vicinity of a joint portion between the upper surface of the lower workpiece and the inner peripheral surface of the small-diameter through hole in the upper workpiece.   The spot welding method according to claim 1 or 2, wherein a plurality of upper workpieces each having a small-diameter through hole are overlapped, and a laser beam is irradiated from a direction inclined with respect to the axis of the small-diameter through-hole. A spot welding method, comprising: irradiating the inner peripheral surface of the small-diameter through hole with reflected light of laser light in the through-hole, and melting and welding the inner peripheral surface of the small-diameter through hole. A spot welding method in which spot welding is performed by stacking a plurality of plate-shaped workpieces,
(A) forming a through-hole having the same diameter or a small diameter in each upper work as a thickness dimension when the upper work is overlaid on a plurality of upper works to be overlaid on the lower work;
(B) A step of superimposing each upper work on the lower work in a state where the through holes are combined.
(C) a step of irradiating the upper surface of the lower workpiece with laser light in a state inclined with respect to the axis of the through hole;
(D) a step of melting and welding the inner peripheral surface of each through-hole by reflected light of a laser beam on the inner peripheral surface of the through-hole in each upper work;
A spot welding method comprising the steps of:   5. The spot welding method according to claim 4, wherein the focal position of the laser beam is set in the vicinity of a joint portion between the upper surface of the lower workpiece and the inner peripheral surface of the through hole in the upper workpiece on the lower workpiece. A spot welding method characterized by the above.   The spot welding method according to claim 4 or 5, wherein a hole processing for weight reduction is performed in advance on a workpiece that is overlapped between a lower workpiece and an uppermost workpiece. .   This is a spot welding method in which a plurality of plate-like workpieces are overlapped and laser welding is performed, and the amount of heat stored in the workpiece is suppressed when a laser beam is irradiated on a curved line such as a circle around the spot welding point. Therefore, the spot welding method is characterized in that the output of the laser beam is reduced stepwise or continuously as it proceeds from the welding start position to the welding end position.   A welded product comprising a plurality of plate-like upper workpieces stacked on a plate-like lower workpiece, wherein the diameter of the welded portion where the plurality of upper workpieces are spot-welded by laser light to the lower workpiece, A welded product having the same diameter or smaller than the overlap thickness of a plurality of upper workpieces.   It is a welded product provided with a plurality of plate-like upper workpieces stacked on a plate-like lower workpiece, and has a melted and solidified metal inside each through hole formed in each upper workpiece. A featured welded product. 10. The welded product according to claim 8 or 9, wherein a workpiece for weight reduction is provided in the workpiece overlapped between the lower workpiece and the uppermost workpiece.

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