JPH05152652A - Laser power supply device - Google Patents

Abstract

PURPOSE:To shorten machine tact by ensuring a desired alteration adjustment for alteration of welding conditions and the like effectually in a short time. CONSTITUTION:Charge-switching field effect transistors F1 and F2 are connected between parallel-connected two capacitors C1, C2 and an input terminal 10. These transistors F1, F2 are controlled in their on/off operations by charge control parts 22, 24 through driver circuits 12, 14. In contrast, NPN transistors Tr1 and Tr2 are connected between both capacitors C1, C2 and a lamp 20 for discharging power of each capacitor to the side of the lamp 20 as a switching element. Theses transistors Tr1, Tr2 are controlled in their on/off operations by first and second lamp lighting discharge control parts 34, 36 through driver circuits 16, 18. A main control part 42 control the whole of the device and respective portions, and a charging voltage set part 40 provides charging voltage setting values of the respective capacitors C1, C2.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device for oscillating and outputting laser light by turning on a lamp for laser excitation by discharge energy from a capacitor.

2. Description of the Related Art In a solid-state laser such as a YAG laser, electric energy is temporarily stored in a condenser, and the energy is discharged from the condenser to an excitation lamp such as a xenon lamp to turn on the excitation lamp and to change its emission energy. The laser medium is irradiated to cause laser oscillation. In welding using this type of laser, when one welding point is welded by one laser oscillation, a considerable amount of electric power is instantaneously discharged (supplied) from the capacitor to the lamp at each laser oscillation. It takes a considerable time to return the voltage of the capacitor to the reference value. For example,
When a capacitor with a capacity of 15000 μF is used, this capacitor is discharged from a reference voltage of 500 V for 5 ms, and the charged voltage of 333 V is returned to the reference voltage by a constant current of 10 A, the required charging time is about 250 m.
sec. Therefore, in this case, the transition time (machine tact) from each welding point to the next welding point cannot be made shorter than about 255 ms.

In the conventional laser power supply device, the machine tact is limited by the charging time of the capacitor as described above, and it is difficult to improve the productivity of the welding process. In order to shorten the charging time, it is conceivable to increase the power supply voltage for charging or increase the charging current, but doing so limits the size of the power supply circuit and reduces the power consumption efficiency. .. Also, when changing the welding conditions, especially the laser output, depending on the welding point,
Generally, this is done by changing the capacitor charging voltage, but with conventional laser power supply devices, it takes time to change and adjust the capacitor charging voltage, so welding under the new welding conditions immediately starts welding to the next welding point. It was difficult to do. Further, in the case of adjusting to lower the charging voltage of the capacitor, since the energy of the capacitor is discharged to the discharging circuit for adjusting the charging voltage, the charged energy must be wasted. The present invention has been made in view of the above problems, and a laser power supply device capable of shortening machine tact by performing necessary change adjustments in a short time and efficiently with respect to changes in welding conditions. The purpose is to provide.

In order to achieve the above object, a laser power supply device according to the present invention is a laser power supply device for driving a lamp for laser excitation by discharging energy stored in a capacitor. A plurality of capacitors connected in parallel to each other, a capacitor charging means for independently charging the plurality of capacitors to an arbitrary set voltage, and a desired power supply to the lamp at a desired timing. And a capacitor discharging means for individually discharging the plurality of capacitors.

According to the present invention, after discharging the first capacitor and turning on the laser excitation lamp with the first discharge energy, the second capacitor is discharged at an arbitrary time and the second discharge energy is discharged. The lamp can be turned on. Accordingly, for example, when the laser power supply device of the present invention is used for laser welding, laser welding can be performed on one welding point and then laser welding can be immediately performed on the next welding point. Can be shortened. Also, since the discharge energy from each capacitor can be set independently to any amount, even when changing the welding conditions for each welding point, it does not take time to adjust the capacitor charging voltage, etc., and at any timing. Laser light can be generated with a laser output according to each welding condition.

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows the configuration of a laser power supply device for laser welding according to an embodiment of the present invention. In this laser power supply device, two capacitors C1 and C2 are connected in parallel with each other with respect to a laser pumping lamp 20. Between the capacitors C1 and C2 and the input terminal 10, field effect transistors (FET) F1 and F2 are connected as switching elements for charging the capacitors, respectively. The on / off operation of these transistors F1 and F2 is performed by the charge control unit 2 via the drive circuits 12 and 14, respectively.
2, 24. On the other hand, capacitors C1 and C2
Between the lamp 20 and the lamp 20 as a switching element for discharging the electric power of each capacitor to the lamp 20 side.
N-type transistors Tr1 and Tr2 are connected to each other. The on / off operation of these transistors Tr1 and Tr2 is performed through the drive circuits 16 and 18, respectively.
It is controlled by the discharge control units 34, 36 for lamp lighting. Further, in parallel with the capacitors C1 and C2, a discharge circuit QH for reducing the charging voltage of each capacitor to the set voltage
1, QH2 are connected respectively. These discharge circuits QH1 and QH2 have resistors R1 and R2 and NPN type transistors tr1 and tr2 connected in series to form transistors tr1 and t2.
In this configuration, protection diodes d1 and d2 are connected in parallel with r2. The on / off operation of these transistors tr1 and tr2 is performed by the first and second voltage adjustment discharge control units 2
Controlled by 8, 32. The terminal voltages of the capacitors C1 and C2, that is, the charging voltages V1 and V2 are detected by the first and second charging voltage detection circuits 26 and 30, respectively. The charging voltage measurement value v1 obtained from the first charging voltage detection circuit 26 for the capacitor C1 is given to the first charging control unit 22 and the first voltage adjusting discharge control unit 28. On the other hand, for the capacitor C2, the second charging voltage detection circuit 3
The charging voltage measurement value v2 obtained from 0 is given to the second charging control unit 24 and the second voltage adjusting discharge control unit 32. The charging voltage setting unit 40 gives the charging voltage setting value s1 for the capacitor C1 to the first charging control unit 22 and the first voltage adjusting discharge control unit 28, and the charging voltage setting value s2 for the capacitor C2 is set to the second value. It is given to the charge control unit 24 and the second voltage adjustment discharge control unit 32.
The charging voltage set values s1 and s2 can be changed at any time by the control signal from the main control unit 42 and the set value data. The main control unit 42 controls the entire power supply unit, controls each unit, and exchanges signals with external devices. For the first and second charging control units 22 and 24, the capacitors C1 and C2 are provided. Start signals j1 and j2 for starting the charging of the capacitors C1 and C2 are supplied to the first and second voltage adjusting discharge control units 28 and 32. k1, k2 are given, and the first and second lamp lighting discharge control units 34,
The start signals m1 and m2 for discharging the capacitors C1 and C2 to the lamp 20 side and the stop signals n1 and n2 for ending the discharge are given to the circuit 36, and the trigger circuit 38 is a trigger for lighting the lamp. A timing signal tg for generating a signal is provided. A laser medium, for example, a YAG rod 44 is arranged adjacent to the lamp 20, and when the lamp 20 is turned on, the YA is generated by the light energy.
The G rod 44 is excited to cause laser oscillation. The laser light LB emitted from both end surfaces of the YAG rod 44 due to the laser oscillation is repeatedly reflected and amplified between the output mirror 46 and the reflection mirror 48, and then is output through the output mirror 46 and emitted from a laser (not shown). Is incident on the workpiece through the section or the emission unit. Thereby, laser welding is performed on one welding point. Next, the charging / discharging operation of the capacitor in the laser power supply device having such a configuration will be described. For example, when the capacitor C1 is charged to the set voltage (reference voltage) S1, the main control unit 42 gives the charging start signal j1 to the first charging control unit 22 to turn on the charging transistor F1. This allows
The direct current charging current i1 from the input terminal 10 is the transistor F.
Is supplied to the capacitor C1 via 1
The charging voltage V1 of the battery rises. As the charging voltage V1 of the capacitor C1 rises, the first charging voltage detecting circuit 26
The obtained voltage measurement value v1 also rises. The measured voltage value v1 is the set value s1 from the charging voltage setting section 40.
If the first charge control unit 22 and the transistor F
1 is turned off to end the charging of the capacitor C1. When the capacitor C2 is charged to the set voltage (reference voltage) S2, the charging operation similar to that described above is performed by the charging transistor F1, the main control unit 42, the second charge control unit 22, the second charge voltage detection circuit 26 and the like. Is done. When the capacitor C1 is discharged to light the lamp 20, the main control unit 42 supplies the discharge starting signal m1 to the first lamp lighting discharge control unit 34 to turn on the discharging transistor Tr1. As a result, the electric power stored in the capacitor C1 is discharged to the lamp 20 side through the transistor Tr1 and the lamp 20 is lit by the discharge current I1. When the lamp 20 is turned on, the light energy causes the YAG rod 4
4 laser-oscillates. The main controller 42 controls the first lamp lighting discharge controller 34 after a lapse of a predetermined time from the discharge start time.
The discharge stop signal n1 is applied to the discharge transistor Tr1
To turn off. By such discharge, the capacitor C
The charging voltage V1 of 1 drops from the reference voltage to a voltage lower by a predetermined value. When the capacitor C2 is discharged, the discharging operation similar to the above is performed by the discharging transistor Tr2, the main control section 42, the second lamp lighting discharge control section 36 and the like. When the capacitors C1 and C2 are discharged, the charging transistors F1 and F2 are kept off. In this way, by disconnecting the input terminal 10 side and the capacitors C1 and C2 from each other during the discharge time, the discharge currents I1 and I2 are not affected even if the power supply voltage or the input voltage E0 fluctuates. Output is obtained. Discharge circuit QH
1 operates so that when the charging voltage V1 of the capacitor C1 is higher than the set value S1, the capacitor C1 is discharged so that the charging voltage V1 matches the set value S1. When changing the set value S1 to a low value while the charging voltage V1 is equal to the set value S1, the main controller 42 gives the start signal k1 to the first voltage adjusting discharge controller 28 to turn on the transistor tr1. Let As a result, a discharging current flows from the capacitor C1 to the discharging circuit QH1, the capacitor charging voltage V1 drops, and the first charging voltage detecting circuit 26
The measured voltage value v1 from the new set value s1 '
If the first voltage adjustment discharge control unit 28 coincides with, the first voltage adjustment discharge control unit 28 turns off the transistor tr1 to stop the discharge. Discharge circuit Q
Also in H2, the same operation is performed by the second voltage adjustment discharge control unit 32 and the like. Next, the operation of the laser power supply device of this embodiment in a concrete laser welding scene will be described with reference to FIGS. First, FIGS. 2 and 3 are examples of laser welding a large number of welding points under the same welding conditions. As shown in FIG. 3, the two metal plates 50, 52
A large number of welding points P1,
This is a case where P2, ..., Pn are set, and a constant laser beam is applied to each welding point Pi to join the two metal plates 50 and 52 together. In this case, in the present laser power supply device, the capacitor C1 is repeatedly charged and discharged with the characteristics shown in FIG. 2A, so that the capacitor C1 is charged with a constant cycle T0 as shown in FIG. 2B. While supplying the discharge current (lamp driving current) I1 to the lamp 20,
By repeatedly charging and discharging the capacitor C2 with the characteristics shown in (C), the time is shifted by a half cycle (T0 / 2) with respect to the discharge current I1 as shown in (D) of FIG. A discharge current (lamp driving current) I2 is supplied to the lamp 20 from the capacitor C2 at a constant period T0. As a result, the lamp 20 is turned on each time the discharge currents I1 and I2 flow, and the light energy causes the YAG rod 44 to oscillate as shown in FIG. 2 (E). As a result, in FIG. 3, the odd-numbered welding points P1, P3, ...
The welding is performed by the laser beam generated by the discharge of 1, and the even-numbered welding points P2, P4, ... Are welded by the laser beam generated by the discharge of the capacitor C2. In this laser power supply device, for example, the capacitors C1 and C2 each have a capacity of 15000 μF, a reference voltage (charging voltage immediately before the start of discharging) is 500 V, a discharging time is 10 ms, a charging voltage at the end of discharging is 333 V, and a charging current is 5 A. In this case, the required charging time T0 for each of the capacitors C1 and C2 is about 250.
msec, each charge / discharge cycle is about 255 m
Limited to s. However, since the capacitors C1 and C2 are alternately charged and discharged by shifting the time by a half cycle, the laser oscillation can be repeated in a cycle of about 128 ms in the entire apparatus. As a result, the laser welding time interval can be halved, and the machine tact can be greatly shortened. Therefore, in FIG. 3, the welding point P
The total required welding time for 1, P2, ... Pn can be greatly shortened. Next, FIG. 4 and FIG. 5 are examples of laser welding a large number of welding points under different welding conditions. For example, as shown in FIG. 4, a small metal piece 56 and a large metal piece 58 are superposed on a metal plate 54 serving as a substrate, and a small pair of welding points Pa1 and Pa2 are set for the smaller metal piece 56. The larger metal piece 56
Is a case where a large pair of welding points Pb1 and Pb2 are set and the metal pieces 56 and 58 are joined to the metal plate 54, respectively. In this case, in this laser power supply, first, the capacitor C1 is discharged from the comparatively low reference voltage S1 'for a comparatively short time Ta' to the one welding point Pa1 of the small metal piece 56, as shown in FIG. And then the capacitor C2 to the other welding point Pa2 of the metal piece 56.
Is discharged from the same reference voltage S2 'for the same time Tb' as shown in FIG. 4 (C). As a result, as shown in (B) and (D) of FIG. 4, relatively small discharge currents I1 'and I2' from both capacitors C1 and C2 are fed back and forth to the lamp 20,
The lamp 20 is turned on each time. As a result, (E) of FIG.
Laser outputs W1 'and W2' are obtained as shown in FIG. In addition,
The laser irradiation point of the laser emitting portion moves from the welding point Pa1 to the welding point Pa2 between the end of the discharge of the capacitor C1 and the start of the discharge of the capacitor C2. Next, the welding points Pb1 and Pb2 of the large metal piece 58
Move to. During this time, the capacitors C1 and C2 are charged. However, since the welding points Pb1 and Pb2 at this time require a relatively large amount of welding energy, they are charged to the reference voltages S1 "and S2" higher than the previous time. Then, for one welding point Pb1, the capacitor C1 is connected to the welding point Pb1 for a relatively long time T from a relatively high reference voltage S1 "as shown in FIG.
Then, the capacitor C2 is discharged to the other welding point Pa2 from the same reference voltage S2 "for the same time Tb" as shown in FIG. 4C.
As shown in (B) and (D) of FIG. 4, relatively large discharge currents I1 "and I2" flow back and forth from the two capacitors C1 and C2 and the lamp 2
0, the lamp 20 is turned on each time, and the laser output W as shown in FIG.
1 "and W2" are obtained. Thus, two capacitors C
Since discharge energy can be continuously supplied to the lamp 20 from 1, C2, two sets of welding points (Pa1Pb1) and (Pa2, Pb2) having different welding conditions can be laser-welded in a short time. Next, FIG. 6 and FIG.
Is another example of laser welding multiple welding points under different welding conditions. As shown in FIG. 7, large metal pieces 62C and 62D and small metal pieces 64C and 64D are abutted on the metal plate 60 serving as a substrate, and the larger metal piece 6
Large welding points Pc1 and Pc2 for 2C and 62D
Is set, small welding points Pd1 and Pd2 are set for the smaller metal pieces 64C and 64D, and the metal pieces are joined to the metal plate 60. In this case, in this laser power supply device, first, the welding point P of the large metal piece 62C is
With respect to c1, the capacitor C1 is discharged from the relatively high reference voltage S1 for a relatively long time Ta as shown in FIG. 6 (A), and then the small metal piece 6 facing the metal piece 62C.
Fig. 6 shows the capacitor C2 for the welding point Pd1 of 4C.
(C), the comparatively low reference voltage S2 is discharged for a comparatively short time Tb. And both capacitors C
1 and C2 are charged to the reference values S1 and S2, respectively, and the laser emitting portion is moved to the metal pieces 62D and 64D, in the same manner as above with respect to the welding point Pc2 of the metal piece 62D and the welding point Pd2 of the metal piece 64D. The capacitors C1 and C2 are discharged respectively. As a result, laser welding is performed on each welding point by the laser output as shown in FIG. In this way, the two capacitors C1 and C
2, it is possible to continuously supply different amounts of discharge energy to the lamp 20 and to irradiate the work piece with laser light with different laser outputs continuously. Therefore, even if the welding conditions are changed for each welding point, it does not take time to change and adjust the capacitor charging voltage, so that it is possible to respond in a short time, and the discharging circuits QH1 and QH2 are operated to waste charging power. There is no need to throw it away. Although the two capacitors C1 and C2 are provided in the above-described embodiment, it is of course possible to provide three or more capacitors. Further, the present invention is not limited to laser welding, but can be applied to laser power supply devices for various purposes.

As described above, according to the laser power supply device of the present invention, a plurality of capacitors are connected in parallel with each other for a laser excitation lamp, and the plurality of capacitors are independently and arbitrarily selected. Charge to the set voltage,
Since each capacitor supplies a desired discharge power to the lamp at a desired timing, it is possible to generate a laser beam having an arbitrary laser output at an arbitrary timing. Therefore, for example, when applied to laser welding, it is possible to perform laser welding for one welding point and then immediately perform laser welding for the next welding point, shorten the machine tact, and reduce the welding time. Even when the welding condition is changed for each point, it is possible to generate the laser output according to each welding condition at an arbitrary timing without spending time for adjusting the capacitor charging voltage and the like.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a laser power supply device according to an embodiment of the present invention.

FIG. 2 is a timing diagram showing a first specific example for explaining the operation of the laser power supply device of the embodiment.

FIG. 3 is a perspective view showing a first specific example for explaining the operation of the laser power supply device of the embodiment.

FIG. 4 is a timing diagram showing a second specific example for explaining the operation of the laser power supply device of the embodiment.

FIG. 5 is a perspective view showing a second specific example for explaining the operation of the laser power supply device of the embodiment.

FIG. 6 is a timing diagram showing a third specific example for explaining the operation of the laser power supply device of the embodiment.

FIG. 7 is a perspective view showing a third specific example for explaining the operation of the laser power supply device of the embodiment.

[Explanation of symbols]

 20 Laser Excitation Lamp 22 First Charging Control Section 24 Second Charging Control Section 26 First Charging Voltage Detection Circuit 30 Second Charging Voltage Detection Circuit 34 First Lamp Lighting Discharge Control Section 36 Second Lamp Lighting discharge control unit 40 Charging voltage setting unit 42 Main control unit

Claims (1)

[Claims] 1. A laser power supply device for driving a lamp for laser excitation by discharging energy stored in a capacitor, wherein a plurality of capacitors connected in parallel to the lamp and the plurality of capacitors are independent of each other. And a capacitor discharging unit that individually discharges the plurality of capacitors so as to supply a predetermined electric power to the lamp at a predetermined timing, respectively. And laser power supply.