JPH01278982A - Laser beam machine - Google Patents

Abstract

PURPOSE:To form the laser burst having a different power density various timely by making a laser pulse variable at the specified energy value per pulse and forming the burst by generating a lot with the specified high speed repeating. CONSTITUTION:The body to be worked is worked by discharging an exciting lamp 4 by its lighting and generating a laser pulse by exciting a laser lot 6 by this exciting lamp 4. The laser pulse is set at <=0.5 joule at its energy value per pulse and variable at <=0.5 joule. The burst is formed by generating a large number of laser pulses with the high speed repeating of 1-2kHz within the specified time and the timely power distribution of each burst is made formable in an optional shape by the circuit operation within the power source unit for pulse generation. The time width and frequency of the burst are made so as to be variable.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a laser processing device suitable for use in metal welding, cutting, drilling, etc., and particularly relates to an improvement in the laser pulse. Regarding.

(Prior Art) Laser processing equipment is generally used for welding, cutting, drilling, etc. of metals. Three conventional examples of this type of laser processing equipment are shown in Figs. 4, 5, and 5. It is constructed as shown in FIG. Note that the same parts in each figure are given the same reference numerals. 'First, in the case of FIG. 4, during operation, energy storage capacitors 3I to 3. to charge. Then, these capacitors 31-3. The heavy charges are discharged when the excitation lamp 4 becomes low impedance due to the application of the triggering high voltage pulse. This discharge current is generated by the capacitor 3I and the inductor 51, the capacitor 32 and the inductor 52, etc.
...Since it is based on a PFN circuit of capacitor 3° and inductor 5n, capacitors 3□ to 3. The discharge occurs in this order, forming a trapezoidal shape. Further, the laser output (laser pulse, the same hereinafter) waveform is almost the same as the discharge current waveform. These waveforms are shown in FIGS. 7(a) and (b).

In addition, 6 in FIG. 4 is a laser rod excited by the excitation lamp 4, and mirrors 7.8 are provided on both sides of this laser rod 6.

Next, in the case of FIG. 5, during operation, the current from the DC power supply 1 is passed through the resonant charging inductor 9 to the thyristor 10, which is a switching element. The energy storage capacitor 31-3° is charged through ~10°. This charging is performed for the number of capacitors determined by the required laser pulse width.

For example, in the case of a pulse width of two steps, capacitor 38.
Charge only 3□. Discharging after completion of charging is carried out in the same manner as in the case of FIG. 4 above.

The discharge current waveform and laser output waveform in the case of Fig. 5 are as follows:
The result is as shown in FIGS. 7(a) and 7(b).

Also, compared to the case shown in Fig. 4, the pulse width can be selected in n stages, and each capacitor 3□, with a voltage approximately twice that of the DC power supply 1,
3□ is charged and has the advantage of being energy efficient.

Note that 11-. in FIG. 11-+ is a diode, 12,
．． 12°-+, 12+ are inductors, 13 is current-limiting resistor,
14 is a simmer power supply.

Next, in the case of FIG. 6, during operation, the current from the DC power supply 1 is switched by, for example, the GTO switch 15 with a necessary pulse width φ repetition. The discharge current waveform and laser output waveform are as shown in FIGS. 8(a) and 8(b).

It is also possible to change the pulse width and repetition, and the discharge current waveform and laser output waveform at that time will be as shown in FIGS. 9(a) and 9(b).

Note that 16 in FIG. 6 is an inductor.

(Problems to be Solved by the Invention) The conventional example described above has the following disadvantages in terms of the number of repetitions and pulse width modulation.

First, in terms of the number of repetitions, even in the case of FIG. 6, where the fastest repetition is obtained, the switching frequency is limited by the performance of the switching element (less than IKHz).

Next, from the point of view of pulse width modulation, modulation is not possible in the case of FIG. In the case of FIG. 5, the repetition rate can be changed appropriately, but it is limited to a low frequency (approximately 50 Hz or less), and the pulse width is variable only in n steps. Furthermore, in the case of Fig. 6, it is possible to vary the repetition and pulse width modulation almost freely, but due to the performance of the switching element, the current value is kept lower than in the cases of Figs. 4 and 5. In addition, there is also the above-mentioned restriction in terms of the number of repetitions.

゛ The present invention eliminates the disadvantages of the conventional example, and provides a laser processing device that is capable of high-speed repetitive pulse oscillation that has never been seen before, and as a result, is capable of burst oscillation consisting of a collection of small pulses that are repeated at high speed. The purpose is to provide.

[Structure of the Invention] (Means for Solving the Problems) The present invention involves lighting and discharging an excitation lamp, exciting a laser rod with the excitation lamp to generate a laser pulse, and machining a workpiece with the laser pulse. In the laser processing device, the laser pulse has a variable energy value per pulse of 0.5 Joule or less, and is generated in large numbers at a high repetition rate of 1 to 2 KHz within a predetermined time to form a burst, The laser processing device is configured such that the temporal power distribution of each burst can be shaped into any shape by operating the circuit within the pulse generation power supply unit, and furthermore, the time width and frequency of the burst can be varied. .

(Function) According to the present invention, high-speed repetitive pulse oscillation, which could not be obtained in the conventional example, has become possible, and as a result, burst oscillation, which is a collection of small pulses that are high-speed repetitive, has become possible. By combining these small pulses, it is possible to create laser bursts with various temporally different power densities, which is extremely effective when used in welding processes and the like.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

The laser processing apparatus according to the present invention is constructed as shown in FIG. 1, and the same parts as in the conventional example are given the same reference numerals.

That is, the + side of the DC power supply 1 is connected to the thyristors 10I to 10. which are switching elements via the resonant charging inductor 9.
connected to the anode of Each thyristor 10. ~1
0. The cathodes of the energy storage capacitors 3I-3° are connected to the + sides of the energy storage capacitors 3I-3°, and the thyristors 171-17. are switching elements. connected to the anode of Each thyristor 17. ~17. The cathode of the inductor is 18° to 18. The anode side of the excitation lamp 4 is connected to the positive side of the simmer power supply 14 via the current-limiting power supply 13. The cathode side of the excitation lamp 4 and one side of the simmer power supply 14 are connected to one side of the DC power supply 1 . In addition, the energy storage capacitor 3
1-3. The - side of is also connected to one side of the DC power supply 1.

During operation, current from the DC power supply 1 passes through the resonant charging inductor 9 and the thyristors 101 to 10 to charge the energy storage capacitors 31 to 37. This charging is performed for the number of capacitors determined by the required laser pulse width. For example, in the case of a pulse width of two steps, only 3.13□ of capacitors are charged.

On the other hand, in the case of discharging, the present invention differs from the PFN circuit consisting of 0 stages as in the conventional example (Fig. 5);
+(i-1 to n) are each combined with an inductor 18° (i-1 to n) to form a one-stage PFN circuit. Furthermore, each of them has a thyristor 17+(i-1 to n).

Therefore, by changing the time interval of the gate pulses to each of the thyristors 17+ (i-1 to n), the discharge current waveform and laser output waveform can be changed as shown in FIG. 2.

That is, FIGS. 2(a) and (b) show Cyrisk 171 to 17.
Although the gate pulses to 1 are equally spaced, Fig. 7(a),
This is a case where input is made at a wider interval than in case (b),
A combination of small pulses with a duty of 50% forms one burst.

In addition, FIGS. 2(c) and 2(d) show the thyristors 17° to 17°.
This is an example in which the gate pulses are spaced unequally, ie, the small pulses are sparse in the head of the burst, dense in the middle, and sparse again in the tail.

As described above, in the laser processing apparatus of the present invention, various regulations are implemented in order to achieve the purpose.

That is, the excitation lamp 4 is lit and discharged, and this excitation lamp 4
The laser lot 6 is excited to generate a laser pulse 6, and a workpiece (not shown) is processed by this laser pulse. The energy value of each laser pulse is 0.5 Joule. is set to below, and is also 0.5
It can be varied below joules. Also, for a predetermined period of time (for example, 10
m5) at a high speed repetition rate of 1 to 2 KHz (e.g. 2
0 pulse) is generated to form a burst as described above, and the temporal power distribution of each burst can be made into any shape by circuit operation within the pulse generation power supply unit. Furthermore, the structure is such that the burst time width and frequency can be varied.

[Effect of the invention] According to this invention, an unprecedented high-speed repetition rate of 1 to 2K can be achieved.
Hz) pulse oscillation becomes possible, and as a result, Fig. 2(a)
), Cb), (e), and (d) burst oscillations consisting of a collection of small pulses that repeat at high speed are now possible.

Also, by combining small pulses that are repeated at high speed, it is possible to create laser bursts with various temporally different power densities. As a result, in the case of FIGS. 2(a) and 2(b), due to thermal and other reasons for the workpiece, the conventional method shown in FIG.
This may be more advantageous than processing using laser pulses as shown in a) and (b).

In other words, in conventional welding using a rectangular laser output waveform, welding defects such as undercuts and bubbles caused by the sudden rise of the waveform can cause the power density to change over time. By using a laser, it has become possible to prevent the output waveform from rising slowly.

Furthermore, in the cases of FIGS. 2(c) and 2(d), the temperature rise of the workpiece is approximately as shown in FIG. 3(b), which is particularly advantageous in welding.

Also, by setting the upper limit of the energy of small pulses,
Each element of the discharge circuit system of capacitor 3+ (i=1 to n), that is, thyristor 17+ (i-1 to n) and 18+ (i=1
-n) can be made smaller. As a result, it becomes possible to use small and inexpensive elements.

Conventionally, when using a laser for welding, the high-output energy was divided according to the number of welding points, and then filters were used to adjust the energy to each individual welding point, resulting in the energy being wasted. .

However, in the present invention, by performing burst oscillation using small pulses that are repeated at high speed, it is possible to combine the number of pulses and supply optimal energy to the workpiece.

In addition, by equipping a large number of low-output, small-sized lasers, it has become possible to design a highly flexible production system that can accommodate differences in the number of welding points and welding energy.

[Brief explanation of the drawing]

FIG. 1 is a circuit configuration diagram showing a laser processing apparatus according to an embodiment of the present invention, and FIG. 2 (a), (b), (C), (d)
3(a) and 3(b) are signal waveform diagrams showing the discharge current waveform and laser output waveform in the laser processing apparatus of the present invention.
1 shows a signal waveform diagram and a temperature characteristic diagram showing the relationship between the laser output waveform and the temperature of the workpiece in the laser processing apparatus of the present invention, and FIGS. 4, 5, and 6 show three diagrams of the conventional laser processing apparatus.
A circuit configuration diagram showing an example, FIGS. 7(a) and 7(b) is a signal waveform diagram showing the discharge current waveform and laser output waveform in a conventional laser processing apparatus (FIGS. 4 and 5), and FIG. a), (
b) and FIGS. 9(a) and 9(b) are signal waveform diagrams showing the discharge current waveform and laser output waveform in the conventional laser processing apparatus (FIG. 6). 1... DC power supply, 31-3. ,...capacitor, 4
. . . Excitation lamp, 6 . Laser rod, 9 . . . Resonance charging inductor, 101 to 10. ... Thyristor, 13... Current-limiting power supply, 14... Simmer power supply, 17,
~17°...Thyristor, 181~18°...Inductor. Applicant's agent Patent attorney Takehiko Suzue t (Haru V) Figure 2 Figure 4 f9 Figure 5 C''~8 t (hours)

Claims (1)

[Claims] In a laser processing device that lights and discharges an excitation lamp, excites a laser rod with the excitation lamp to generate a laser pulse, and processes a workpiece with the laser pulse, the laser pulse is The energy value per pulse is made variable at 0.5 Joule or less, and a large number of bursts are generated within a predetermined time at a high repetition rate of 1 to 2 KHz to form a burst, and the temporal power distribution of each burst is determined by A laser processing device characterized in that it is configured to be able to form any shape by operating a circuit within a power supply unit, and further to be able to vary the time width and frequency of the burst.