JP5013720B2 - Laser processing method - Google Patents

Description

  The present invention relates to a laser processing method for performing seam welding by irradiating a laser beam.

  When performing seam welding with laser light, the conventional processing method uses a pulsed excitation laser oscillator to generate a circular weld shape with one pulse, and repeats laser irradiation while overlapping a part to perform seam welding. Is going. Alternatively, a continuous excitation laser oscillator is used, and seam welding is performed at a time while continuously irradiating the workpiece with the laser.

  In Patent Document 1, although different from welding, in zapping, a laser beam periodically emitted from a laser oscillator is applied to a mask having a slit-shaped opening to shape the laser beam into a rectangular shape. The substrate that is the object to be irradiated so that the region irradiated with the post-shaping laser beam and the region irradiated with the next post-shaping laser beam emitted after this shaping laser beam overlap at least partially. The laser beam is radiated while moving.

  In Patent Document 2, although different from laser welding, in electric welding, a vertically divided tank is supported by a robot arm in a freely rotating state, and a tank joint flange is sandwiched between upper and lower electrode wheels. Perform seam welding. That is, while rotating the electrode wheel, a direct current is intermittently passed between the electrode wheels to seam weld the joint flange portion. At this time, by changing the direct current flowing between the upper and lower electrode rings in proportion to the relative speed of the upper and lower electrode rings with respect to the joint flange, seam welding is performed while keeping the overlap amount between the weld masses constant at all times. Have gained stable welding quality.

  Furthermore, in Patent Document 3, although different from the seam welding method using laser light, the welding torch for supplying the welding wire is swung back and forth along the welding line of the material to be welded, along the welding line. A method of performing welding while moving forward at a constant speed is described.

JP 2001-297692 A JP 09-108443 A JP 60-015068 A

  However, the above-described prior art has the following problems.

  Conventionally, in laser welding of aluminum alloys and the like, in the case of seam welding with a pulse excitation laser oscillator, the weld shape is circular and the keyhole generated during deep penetration welding is small. Further, there is a problem in that molten steam is difficult to escape and welding failure due to spatter or remaining bubbles tends to occur.

  In addition, there is a problem in that the machining speed is slow because the amount of advance in one pulse is small.

  In addition, in the case of seam welding using a continuous excitation laser oscillator, there is a problem in that the effect of heat on the workpiece is large because the laser is constantly irradiated.

  The present invention has been made in view of such a problem, and in a case where seam welding is performed by repeatedly performing pulsed laser irradiation while scanning a laser beam at a high speed, laser processing is performed at a high processing speed to prevent poor welding. The purpose is to provide the law.

The laser processing method according to the present invention is a laser processing method in which laser light that is repeatedly oscillated in a pulse shape is irradiated and welded, and is formed by scanning the laser light while irradiating one pulse of laser light. A linear welded portion formed by scanning a laser beam while irradiating a laser beam of one pulse following the laser beam, and a pulse of laser beam subsequently following the irradiation of the laser beam of one pulse This is characterized in that seam welding is sequentially performed so as to overlap each other at the end portions of the linear welded portions by reversing the irradiation start position by a predetermined distance .

The pulse width of the record laser light, it is preferable to be 10 to 50 ms.

  A laser processing apparatus according to the present invention is a laser processing apparatus using the laser processing method, wherein a laser oscillator that periodically oscillates pulsed laser light, and an optical fiber that guides the laser light oscillated by the laser oscillator A collimating lens that collimates the laser light guided to the optical fiber, a plurality of scan mirrors that reflect the light that has passed through the collimating lens, and a reflected laser light by variably controlling the angle of the scan mirror A scan mirror drive unit that scans the laser beam, an fθ lens that collects the laser light reflected by the scan mirror, and a control unit that controls the operation timing of the scan mirror drive unit and the laser oscillator. Features.

  The laser oscillator is preferably a pulsed pump laser oscillator.

  According to the present invention, since the keyhole is formed in a linear shape by making the welding shape of one pulse linear, it is possible to avoid welding defects caused by surface roughness due to spatter or residual bubbles, cracks, and the like. Can do. Further, it can be processed at a higher speed than seam welding by a conventional pulse excitation laser oscillator having a circular welding shape. Furthermore, since there is a cooling time of the workpiece after the one-pulse laser irradiation until the next laser irradiation, the thermal influence on the workpiece can be reduced.

  Embodiments of the present invention will be specifically described with reference to the accompanying drawings. FIG. 1 is a perspective view showing a laser processing apparatus according to an embodiment of the present invention. FIG. 2 is an operation diagram showing the laser processing process of the present invention.

  As shown in FIG. 1, the laser processing apparatus according to the present embodiment includes a pulse excitation laser oscillator 1 that can oscillate in a pulsed manner, a scan optical unit 10 that scans a laser beam by oscillating a mirror using a drive system, It comprises a controller 9 that synchronizes the operations of the scanning optical unit 10 and the laser oscillator.

  The pulse excitation laser oscillator 1 can repeatedly oscillate with a pulse width of 10 to 50 ms, for example. An optical fiber 2 is connected to the pulse excitation laser oscillator 1, and the oscillated laser light is guided to the scanning optical unit 10 by the optical fiber 2.

  The scan optical unit 10 includes a collimating lens 4 that collimates the laser light 3 incident from the pulse excitation laser oscillator 1 through the optical fiber 2, a motor-driven scan mirror 5 that reflects and scans the laser light 3, and A motor 6 that drives and controls scanning of the scan mirror 5 and an fθ lens 7 that focuses the laser light 3 on a focal plane are configured. The scan optical unit 10 is provided with means for driving the scan of the scan mirror 5, whereby the laser beam can be scanned at a high speed.

  Next, a laser processing process obtained by using this embodiment will be described with reference to FIGS. First, as shown in FIG. 2A, the scanning mirror installed in the scanning optical unit is scanned to the position (4) from the angle at which the laser beam can irradiate the position (1). In the middle, the controller takes timing, and the first pulse of laser irradiation is performed while scanning between (2) and (3). By this operation, a linear welded shape is obtained. Next, as shown in FIG. 2B, during the second pulse of laser irradiation, the scan mirror is returned to the position (5) to an angle at which the laser beam can be irradiated. Next, as shown in FIG. 2C, the scan mirror is scanned to an angle at which the laser beam can be irradiated at the position (8). In the middle, the controller takes the timing, and the second pulse of laser irradiation is performed while scanning between (6) and (7). By performing seam welding by repeating the above operations, as shown in FIG. 2 (d), the end portions of the respective linear welded portions are overlapped to form a welded portion in which these welded portions are connected. Can do.

  Next, the effect of this embodiment will be described. In the laser processing method according to the present invention, a combination of a scanning optical unit capable of high-speed scanning and a pulse-pumped laser oscillator capable of emitting laser with a pulse width of 10 to 50 ms is used to irradiate a laser beam with one pulse. After the laser irradiation of one pulse and before the next irradiation, the laser light driving unit is returned to the original direction by a certain distance and the laser light is again emitted while performing the next one pulse of laser irradiation. Scan ahead and perform seam welding while overlapping the ends of each weld. By making the welding shape of one pulse linear, the keyhole is also formed in a linear shape, so that high-quality seam welding without surface defects due to spatter or remaining bubbles and welding defects such as cracks becomes possible. Further, it can be processed at a higher speed than seam welding by a conventional pulse excitation laser oscillator having a circular welding shape. Furthermore, since there is a cooling time of the workpiece after the one-pulse laser irradiation until the next laser irradiation, the thermal influence on the workpiece can be reduced.

  In this embodiment, a pulse excitation laser oscillator is used. However, a continuous excitation laser may be used, and laser irradiation may be performed at intervals of 10 ms to 100 ms. In addition, although the processing speed is slow, a robot or an XY table may be used for the drive unit, and in this case, the welding quality is improved.

  The present invention can be suitably used for welding electric, automobile, and battery parts.

It is a perspective view which shows the laser processing apparatus which concerns on embodiment of this invention. (A) thru | or (d) are operation | movement diagrams which show the laser processing process of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1; Pulse excitation laser oscillator 2; Optical fiber 3; Laser light 4; Collimating lens 5; Scan mirror 6; Motor 7; f (theta) lens 8;

Claims (4)

A laser processing method of irradiating and welding a laser beam that is repeatedly oscillated in a pulse shape, a linear weld portion formed by scanning a laser beam while irradiating a pulse of laser beam, and a subsequent 1 A linear welded portion formed by scanning a laser beam while irradiating a pulsed laser beam, and after irradiating one pulse of the laser beam, the irradiation start position of the subsequent one pulse of the laser beam is reversed by a predetermined distance. A laser processing method characterized by performing seam welding sequentially so as to overlap each other at the ends of the linear welds by returning them. 2. The laser processing method according to claim 1 , wherein a pulse width of the laser beam is 10 to 50 ms. A laser machining apparatus for carrying out the laser processing method according to claim 1 or 2, a laser oscillator which periodically oscillates a pulsed laser beam, and an optical fiber for guiding the laser light the laser oscillator oscillates, A collimating lens that collimates the laser light guided to the optical fiber, a plurality of scan mirrors that reflect the light that has passed through the collimating lens, and a scan of the reflected laser light by variably controlling the angle of the scan mirror A scan mirror driving unit, an fθ lens for condensing the laser light reflected by the scan mirror, and a control unit for timing the operation of the scan mirror driving unit and the laser oscillator. Laser processing equipment. The laser processing apparatus according to claim 3 , wherein the laser oscillator is a pulse excitation laser oscillator.

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