JPS60115389A - Laser working device - Google Patents

Abstract

PURPOSE:To perform stable laser working with constant output by providing an attenuator for laser light energy and adjusting the energy according to the pulse repeating speed to be controlled in proportion to the speed of a work. CONSTITUTION:An attenuator 6 is provided between an optical resonator mirror 10b and a variable optical system 13 and is driven by a driving part 21. When a material 3 to be worked changes a moving speed, a speed-frequency converter 19 has the Q switch pulses proportional to the respective speeds generated by a driver 20. An attenuator 6 drives a driving part 21 to change the rate of attenuation and to allow transmission of laser light L so as to attain the transmissivity proportional to the pulse repeating speed. The laser light scanned by the system 13 is provided with the pulse width corresponding to the moving speed of the material 3 by such mechanism and since the laser light maintains always the specified output, stable working is accomplished.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a laser processing apparatus, and particularly to an apparatus for performing surface heat treatment.

[Technical background of the invention and its problems]

Processing that reduces core loss by irradiating the surface of an electrical steel sheet with, for example, a laser beam that causes the crystal structure of the steel sheet to become finely divided is being put into practical use. Such surface heat treatment usually uses a YAG laser that continuously excites the Nd:YAG rod and generates high-speed Q-switch pulses.

By the way, the repetition rate of the Q switch pulse is set by the electrical drive frequency of the Q switch, but if this frequency is 1
It has been observed that the pulse output of laser light becomes unstable when the frequency exceeds 0 KHz, and when surface heat treatment is performed using such laser light, the irradiated area receives different heat depending on the laser pulse. In addition, in a relatively stable output range of 10 KHz or less, the surface treatment speed is limited, resulting in inefficiency. On the other hand, if it is necessary to change the interval between 9° irradiation spots by changing the irradiation power of the laser beam depending on processing conditions, it is necessary to significantly change the pulse oscillation repetition rate. When trying to optimize the irradiation processing conditions, it was experimentally found that the laser oscillation output was stabilized within a narrow range depending on the optical excitation conditions of the laser rod, and it was difficult to stabilize it under a wide range of output conditions. This point is a practical drawback.

[Purpose of the invention]

An object of the present invention is to provide an apparatus that can perform processing with stable laser output even if the pulse repetition rate is changed significantly.

[Summary of the invention]

An attenuator is installed to control the energy of the laser beam.

By adjusting the laser beam energy using the above attenuator in proportion to the pulse repetition rate, which is controlled in proportion to the moving speed of the workpiece, stable laser output can be achieved in response to changes in the irradiation conditions of the workpiece. It is designed so that processing can be performed with.

[Embodiments of the invention]

Hereinafter, the present invention will be explained based on drawings showing examples.

Figure t41 shows an embodiment of the present invention, which includes a laser oscillation section (1), a scanning section (2) that scans the laser beam (L) emitted from the laser oscillation section (1), and a scanning section (2) that scans the laser beam (L) emitted from the laser oscillation section (1). Processed product (3
) and a moving unit (4) that moves the laser oscillation unit (1).
) and an attenuator (6) that changes the energy intensity of the laser beam (L).

The laser oscillation section (1) has Nd inside the condensing reflector (7).
, YAG, etc., and excitation lamps (9a) and (9b) arranged to excite this laser rod from both sides.
8), an optical resonator mirror (10a) arranged on the axis of (
For example, an ultrasonic Q-switch element (11
) consists of a solid-state laser blinding device. Note that α
3 is a power source for the excitation lamps (8a) and (8b).

The scanning unit (2) deflects the laser beam (L) in the direction of the workpiece (3) and is connected to a variable optical system (13) that vibrates with a constant amplitude and on the optical path of the deflected laser beam (La) that vibrates with a constant amplitude. It consists of a condensing lens (14J) provided in the

In addition, the moving part (4) includes a drive part (1) to move the workpiece (3) in the direction of the arrow, a large number of moving rollers (II), and a speed detector (1) that detects the speed of the movement.
7). The control unit (5) is a signal control unit (1) that inputs the detection signal of the speed detector Q7) and outputs a control signal.
Camphor, a speed-frequency converter (II) that changes the repetition rate of the Q-switch element aυ by the output signal from this signal control section (Yu), and a driver (rumored that it also attenuates by the output signal from the signal control section Kasumi) The attenuator (6) is provided between one optical resonator mirror (10b) and the variable optical system (131), and the attenuator (6) is provided between one optical resonator mirror (10b) and the variable optical system (131), and Transmittance changes due to changes in
It is made of a well-known material such as a glass disk having portions with different transmittances.

The operation of the above configuration will be explained with reference to FIG.

In Fig. 2, as shown in Fig. 2(a), the workpiece (3
) moves at a relatively slow speed (vl) during time t1, and at time t, moves at a faster speed . In order to correspond to the respective speeds mentioned above, the pulse repetition period is at time t, and the low speed edge and return period T
, and the Q-switch pulse is generated by the driver (21) so that the high-speed edge 9 return period T is obtained during time t. At this time, the excitation lamps (9a) and (9b) are allowed to oscillate under the conditions that the pulse rises stably within the range of Ha-pulse repetitive operation and that the peak output is also a stable output □. Under this optical bombing condition of stable operation, it is not possible to set arbitrary pulse conditions and repetition rate conditions, so the attenuator (6) is driven by the driver (21) as shown in FIG. 2(c). At time t1, the transmittance is TR1, and at time t, the transmittance is TR2 (where TRI >
The amount of attenuation is changed so that the laser beam (L
) to pass through. This allows the variable optical system (13
The laser beam (La) scanned by the laser beam should have an appropriate pulse width depending on the moving speed of the workpiece (3) and an almost constant output power regardless of the pulse width, as shown in Fig. 2(d). I can do it.

〔Effect of the invention〕

As explained above, each pulse output of the Q-switch pulse output of the laser oscillator is set to be within the range of pulse repetition rate that matches the moving speed conditions of the workpiece, and stable output can be obtained under this condition. After setting the excitation input and resonance conditions to oscillate and output the laser beam, the laser output under the low-speed pulse repetition condition is adjusted using an attenuator to match that under the high-speed pulse repetition condition, so that the machining conditions can be changed. It is now possible to process the workpiece with a constant laser output at all times, making it possible to perform highly stable laser processing. Therefore, for example, when performing annealing treatment or gettering by irradiating the surface of a semiconductor material with laser light, a wide area can be processed uniformly at a desired processing speed, and when heat treating an electrical steel sheet with laser light, the electrical steel sheet can be heated. It is now possible to perform uniform heat treatment by adjusting the moving speed of the

Note that the attenuator is not limited to a transmissive one, and may also be an ultrasonic modulation cell, a variable aperture plate, a filter with variable transmittance, or a light attenuation plate having a large number of transmission holes. Further, the variable optical system can be implemented with a polyhedral rotating mirror instead of a vibrating reflecting mirror.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an embodiment of the present invention, and FIG. 2 is an explanatory diagram of the operation. (1)...Laser oscillation section (2)...Scanning section (4)
...Movement part (5)...Control part (6)...Attenuator agent Patent attorney Noriyuki Chika (and 1 other person) + 1 ■l, -1 to -1 -'' Ha /++/ ′+ ρ CO engineering〕 Q ℃ l

Claims (2)

[Claims] (1) A solid-state laser oscillation unit having a Q switch for high-speed edge 9-turn pulses, a scanning unit that condenses and scans the laser beam emitted from the solid-state laser oscillation unit onto a workpiece, and a moving part that moves the laser beam relative to the laser beam; a control part that controls the pulse repetition rate of the Q-switch pulse in proportion to the moving speed of the moving part; A laser processing device comprising: an attenuator that adjusts the output of laser light. (2) Claims characterized in that the attenuator is set to an amount of attenuation that brings the high output side of the laser beam emitted at different outputs close to the low output side in response to changes in the pulse repetition rate. The laser processing device according to item 1.