JP2721887B2 - Laser processing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to a laser processing apparatus suitable for use in welding, cutting, drilling, and the like of metal, and in particular, to an improvement in the laser pulse. About.

(Prior Art) Generally, a laser processing apparatus is used for welding, cutting, drilling, and the like of metal. Three conventional examples of this type of laser processing apparatus are shown in FIGS. It is configured as shown in FIG. The same parts in the respective drawings are denoted by the same reference numerals.

First, in the case of FIG. 4, to charge an energy storage capacitor 3 ₁ to 3 _n through discharge resistor 2 from the DC power source 1 during operation. Then, electric charge of the capacitor 3 ₁ to 3 _n When the excitation lamp 4 becomes a low impedance by application of the trigger high voltage pulse, discharge. This discharge current is
Capacitor 3 ₁ and the inductor 5 _1, because due to the capacitor 3 ₂ and the inductor 5 _2, ... condenser 3 _n and the inductor 5 _n PFN circuit, is discharged in the order of the capacitor 3 ₁ to 3 _n, is substantially trapezoidal. The laser output (laser pulse, hereinafter the same) waveform is almost the same as the discharge current waveform. These waveforms
These are shown in FIGS. 7 (a) and 7 (b).

4 is a laser rod which is excited by the excitation lamp 4. Mirrors 7 and 8 are provided on both sides of the laser rod 6.

Next, the case of FIG. 5, in operation, through the thyristor 10 ₁ to 10 _n current which is a switching element through a resonance charging inductor 9 from the DC power source 1, charges the energy storage capacitor 3 ₁ to 3 _n I do. This charging is performed for the number of capacitors determined by the required pulse width of the laser. For example, if the pulse width is two stages,
Charge only 3 ₁ and 3 ₂ . The discharging after the completion of the charging is performed in the same manner as in the case of FIG.

The discharge current waveform and laser output waveform in the case of FIG. 5 are as shown in FIGS. 7 (a) and 7 (b). Also, the fourth
Compared with the case of FIG., And to choose the pulse width by n stages, it is charged about each capacitor 3 ₁ at twice the voltage, 3 ₂ of the DC power source 1, has a feature that the energy efficiency is good.

Note that 11 _n and 11 _{n-1 in} FIG. 5 are diodes, 12 _n and 1
2 _n-1, 12 ₁ are inductor, 13 current limiting resistor, 14 is simmer power supply.

Next, in the case of FIG. 6, during operation, the current from the DC power supply 1 is switched by the GTO switch 15, for example, with a required pulse width and 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 are ninth.
The results are as shown in FIGS.

 Incidentally, reference numeral 16 in FIG. 6 denotes an inductor.

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

First, from the viewpoint of the number of repetitions, even in the case of FIG. 6 where the fastest repetition is obtained, the switching frequency is restricted by the performance of the switching element (1 KHz or less).

Next, from the point of pulse width modulation, modulation is not possible in the case of FIG. In the case of FIG. 5, the repetition can be changed appropriately, but is restricted by a low eye (about 50 Hz or less), and the pulse width is variable only in n steps. In the case of FIG. 6,
Although the repetition and the pulse width modulation can be changed almost freely, the current value can be suppressed to be lower than in the case of FIGS. 4 and 5 due to the performance of the switching element. is there.

The present invention provides a laser processing apparatus that solves the above-described disadvantages of the conventional example, enables high-speed repetitive pulse oscillation that has not been achieved in the past, and as a result, enables burst oscillation composed of an aggregate of small pulses with high-speed repetition. The purpose is to do.

[Constitution of the Invention] (Means for Solving the Problems) In the present invention, an excitation lamp is turned on and discharged, a laser rod is excited by the excitation lamp to generate a laser pulse, and a workpiece is processed by the laser pulse. In the laser processing apparatus, the energy value of each laser pulse is varied within 0.5 Joules or less, and a large number of laser pulses are generated at high speed repetition of 1 to 2 KHz within a predetermined time to form bursts. The laser processing apparatus is configured such that the temporal power distribution can be changed to an arbitrary shape by a circuit operation in a power supply unit for generating a pulse, and the time width and frequency of the burst can be varied.

(Operation) According to the present invention, high-speed repetitive pulse oscillation, which cannot be obtained in the conventional example, can be performed. As a result, burst oscillation, which is an aggregate of high-speed repetitive small pulses, can be performed. By combining the small pulses, laser bursts having different power densities with time can be produced, which is extremely effective when used for welding or the like.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

A laser processing apparatus according to the present invention is configured as shown in FIG. 1, and the same parts as those in the conventional example are denoted by the same reference numerals.

That is, the + side of the DC power supply 1 is connected to the resonance charging inductor 9.
It is connected to the anode of the thyristor 10 ₁ to 10 _n as a switching element through. Cathode of each thyristor 10 ₁ to 10 _n is connected to the + side of the energy storage capacitor 3 ₁ to 3 _n, thyristor 17 ₁ to 1 which is a switching element
It is connected to the anode of 7 _n. Each of these thyristors 17 _{1 to} 17 _n
The cathode, the inductor 18 ₁ through ~ 18 _n are connected to the anode side of the excitation lamp 4, the anode side of the excitation lamp 4 is limiting power
13 is connected to the + side of the simmer power supply 14. The cathode side of the excitation lamp 4 and the minus side of the simmer power supply 14 are connected to the minus side of the DC power supply 1. Moreover, the energy storage capacitor 3 ₁ to 3 _n of the - side also of the DC power source 1 - is connected to the side.

Now, in operation, current from the DC power source 1 through the thyristor 10 ₁ to 10 _n via a resonant charging inductor 9, charges the energy storage capacitor 3 ₁ to 3 _n. This charging is performed for the number of capacitors determined by the required pulse width of the laser. For example, in the case of the pulse width of the two stages, it charges only the capacitor capacitor 3 _1, 3 _2.

On the other hand, in the case of discharge, the present invention is different from the PFN circuit consisting of n stages as in the conventional example (FIG. 5), each capacitor 3 _i
Each of (i = 1 to n) is combined with an inductor 18 _i (i = 1 to n) to form a one-stage PFN circuit. Further, each of them has a thyristor 17 _i (i = 1 to n).

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

That is, FIGS. 2 (a) and 2 (b) show that the gate pulses to the thyristors 17 _{1 to} 17 _n are at equal intervals.
This is a case where the input is performed with a longer interval than in the case of (b).
A combination of small pulses having a duty of 50% forms one burst.

2 (c) and 2 (d) show the gate pulses to the thyristors 17 _{1 to} 17 _n at unequal intervals, that is, small pulses are sparse at the head of the burst, dense at the center, and tails at the center. Here is an example of sparseness again in the part.

As described above, in the laser processing apparatus of the present invention, various controls are performed to achieve the object.

That is, the excitation lamp 4 is turned on and discharged, and the laser lamp 6 is excited by the excitation lamp 4 to generate a laser pulse 6, and a workpiece (not shown) is generated by the laser pulse.
The laser pulse has an energy value per pulse set to 0.5 joule or less, and can be varied to 0.5 joule or less. In addition, a large number (for example, 20 pulses) is generated at a high speed repetition of 1 to 2 KHz within a predetermined time (for example, 10 ms) to form bursts as described above, and the temporal power distribution of each burst is determined in the power supply unit for pulse generation. Arbitrary shapes are possible by the circuit operation in. Further, it is configured such that the time width and frequency of the burst can be varied.

[Effects of the Invention] According to the present invention, high-speed repetition (1-2K
Hz) pulse oscillation becomes possible, and as a result, burst oscillation consisting of a collection of high-speed repetition small pulses as shown in FIGS. 2 (a), (b), (c) and (d) becomes possible. Was.

In addition, various time-dependent laser bursts having different power densities can be produced by a combination of high-speed repetition small pulses. As a result, in the case of FIGS. 2 (a) and 2 (b), it is more advantageous than the conventional laser pulse shown in FIGS. 7 (a) and 7 (b) for thermal and other reasons for the workpiece. There are things.

That is, in welding using a rectangular laser output waveform in the past, welding defects such as undercuts and bubbles caused by a sharp rise of the waveform are caused by such a laser that can change the power density over time. By adopting it, it was possible to prevent the output waveform from rising slowly.

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

Further, by setting the upper limit of the energy of the small pulse, the capacitor 3 _i the elements of the discharge circuit system (i = 1 to n) i.e. thyristors 17 _{i (i} = _1~n) and 18 _{i (i} = 1~
The rating of n) can be reduced. As a result, a small and inexpensive element can be used.

Conventionally, when a laser is used for welding, after a large output energy is divided according to the number of welding points, in order to match each welding energy, the energy is often wasted by using a filter or the like. .

However, in the present invention, by performing burst oscillation with small pulses of high-speed repetition, it is possible to supply the optimum energy to the workpiece by combining the number of pulses.

In addition, by providing a large number of small power and small lasers,
This makes it possible to design a highly flexible production system that can respond to differences in the number of welding points and welding energy.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a laser processing apparatus according to an embodiment of the present invention, and FIGS. 2 (a), (b), (c) and (d).
FIG. 3 is a signal waveform diagram showing a discharge current waveform and a laser output waveform in the laser processing apparatus of the present invention, and FIGS.
FIG. 4 is a signal waveform diagram and a temperature characteristic diagram showing a relationship between a laser output waveform and a temperature of a workpiece in the laser processing apparatus of the present invention. FIGS. 4, 5, and 6 show three examples of a conventional laser processing apparatus. 7 (a) and 7 (b) are signal waveform diagrams showing a discharge current waveform and a laser output waveform in a conventional laser processing apparatus (FIGS. 4 and 5), and FIG. 8 (a). ),
9 (b) and FIGS. 9 (a) and 9 (b) are signal waveform diagrams showing a discharge current waveform and a laser output waveform in a conventional laser processing apparatus (FIG. 6). 1 ...... DC power supply, 3 ₁ to 3 _n ...... condenser, 4 ...... excitation lamp, 6 ...... laser rod, 9 ...... resonant charging inductor, 10 ₁ to 10 _n ...... thyristors, 13 ...... current limiting power supply ,14……
Shimmer power, 17 ₁ ~17 _n ...... thyristor, 18 ₁ ~18 _n ...... inductor.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Seiji Koshi 72 Horikawacho, Saiwai-ku, Kawasaki City, Kanagawa Prefecture Inside the Toshiba Horikawacho Plant (72) Inventor Keno Sato 72 Horikawacho, Saiwai-ku, Kawasaki City, Kanagawa Prefecture Toshiba Electronics Device Engineering Co., Ltd.

Claims (1)

(57) [Claims] 1. A laser processing apparatus for lighting a discharge of an excitation lamp, exciting a laser rod by the excitation lamp to generate a laser pulse, and processing a workpiece by the laser pulse, wherein the laser pulse is Make the energy value per pulse variable at 0.5 joules or less, and
Generates a large number of bursts at high speed repetition of ~ 2KHz,
The temporal power distribution of each burst can be made to any shape by operating the circuit in the power supply unit for pulse generation,
Further, the laser processing apparatus is configured so that the time width and frequency of the burst can be varied.