WO2022044280A1

WO2022044280A1 - Laser beam generation device and laser machining device

Info

Publication number: WO2022044280A1
Application number: PCT/JP2020/032693
Authority: WO
Inventors: 周治若生; 弘五十嵐; 真吾津田; 義一角田; 秀康町井; 勇一五十嵐
Original assignee: 三菱電機株式会社
Priority date: 2020-08-28
Filing date: 2020-08-28
Publication date: 2022-03-03
Also published as: JP7399302B2; JPWO2022044280A1

Abstract

This laser beam generation device (200) comprises: a laser diode (20); a power supply (10) which supplies current; a reactor circuit (30) which is connected to the power supply (10) and has a variable inductance value; a current path switching circuit (105) configured to switch whether to supply the current output from the reactor circuit (30) to the laser diode; and a control device (13) which controls the current path switching circuit (105) and sets the inductance value of the reactor circuit (30).

Description

Laser light generator and laser processing equipment

This disclosure relates to a laser light generator and a laser processing device.

In the processing fields such as metal welding, metal cutting, and metal marking, gas laser devices such as CO2 lasers or solid-state laser devices such as YAG (Yttrium Aluminum Garnet) lasers that are excited by lamps have been used in the past.

However, in recent years, the output of solid-state laser devices excited by laser diodes (hereinafter referred to as "LD (Laser Diode)") such as fiber lasers and direct diode laser devices that directly output laser light has been increasing. As a result, in the above-mentioned processing field, the replacement of a solid-state laser device by lamp excitation such as a gas laser such as a CO2 laser or a YAG laser with a solid-state laser device or a direct diode laser device by LD excitation such as a fiber laser is progressing. ..

Since the LD is a current drive type element, in a laser light generator using the LD, it is possible to use a constant current source that supplies the LD with a constant drive current required to obtain a desired laser light output. It is common. When using a constant current source, a reactor is generally used to obtain a stable laser beam output. The response speed of the output current slows down due to the storage of electromagnetic energy in the reactor. As a result, there is a problem that a desired laser light output cannot be obtained even if an attempt is made to output a laser according to the processing conditions.

In order to solve such a problem, for example, in the regulator type laser diode driving power supply device disclosed in Japanese Patent Application Laid-Open No. 2009-123833 (Patent Document 1), the LD drive current can be started up at a high speed up to a set current value. It is characterized by that. This laser drive power supply includes a constant current source circuit for supplying a desired constant current to the load circuit, a secondary smoothing reactor connected between the constant current source circuit and the LD, and a constant current source circuit. The first switching element connected in series with the secondary smoothing reactor and connected in parallel with the LD, and the first switching element kept in the ON state while the LD is not made to emit light, and the LD is made to emit light. It has an LD drive control unit that holds the first switching element in the off state when the current is turned off.

Japanese Unexamined Patent Publication No. 2009-123833

The switching type LD drive power supply device described in Patent Document 1 can raise the LD drive current to a certain set current value at high speed, but cannot change the set current value. In recent years, in laser processing machines and the like, it has become necessary to improve the accuracy of the machined surface by changing the set current value according to the shape of the machined surface, and to have a laser beam output specialized for various types of processing. There is.

Further, in the switching type LD drive power supply device described in Patent Document 1, the inductance value of the smoothing reactor is set to a large value in order to alleviate the ripple current when outputting a current drive waveform having a high pulse drive frequency. There is. During the period when the current command value is zero, the switching element connected in parallel to the LD module is turned on, and the energy stored in the smoothing reactor returns the closed circuit between the smoothing reactor and the switching element. In the LD drive power supply, it is necessary to change the laser beam output according to the shape of the machined surface, but since the inductance value of the smoothing reactor is large, it takes time to change to the desired current value and a high peak is achieved. There is a problem that it is difficult to obtain the current output to have.

Therefore, an object of the present disclosure is to provide a laser beam generator and a laser processing apparatus capable of stabilizing the output of a laser beam at high speed and outputting a laser beam having a high peak.

The laser light generator of the present disclosure includes a laser diode, a power supply that supplies a current, a reactor circuit that is connected to the power supply and has a variable inductance value, and whether or not to supply the current output from the reactor circuit to the laser diode. It is provided with a current path switching circuit configured to switch between the two, and a control unit that controls the current path switching circuit and sets the inductance value of the reactor circuit.

According to the present disclosure, the output of the laser beam can be stabilized at high speed, and the laser beam having a high peak can be output.

It is a figure which shows the structure of the laser light generator 200 of Embodiment 1. FIG. It is a figure which shows the structure of the reactor circuit 30 of Embodiment 1. It is a figure which shows the structure of the current path switching circuit 105 of Embodiment 1. FIG. It is a figure which shows another structure of the current path switching circuit 105 of Embodiment 1. FIG. It is a timing chart which shows the operation of the laser light generator 200 of Embodiment 1. FIG. (A) is a diagram showing the current flowing through the LD 20 when the inductance value of the reactor circuit 30 is 10 μH. (B) is a diagram showing the current flowing through the LD 20 when the inductance value of the reactor circuit 30 is 1 μH. (C) is a diagram showing the current flowing through the LD 20 when the inductance value of the reactor circuit 30 is 0.1 μH. It is a figure which shows the structure of the reactor circuit 30c of Embodiment 2. It is a figure which shows the structure of the reactor circuit 30d of Embodiment 3. It is a figure which shows the structure of the reactor circuit 30e of Embodiment 4. It is a figure which shows the structure of the laser light generator 200a of Embodiment 5. It is a figure which shows the structure of the laser light generator 200b of Embodiment 6. (A) and (b) are diagrams for explaining the first method of mechanically changing the inductance value of a reactor. (C) and (d) are diagrams for explaining a second method of mechanically changing the inductance value of the reactor. (E) and (f) are diagrams for explaining a third method of mechanically changing the inductance value of the reactor. It is a figure which shows the change of the inductance value with respect to the length of an air core coil. It is a figure which shows the structure of the laser processing apparatus of Embodiment 8. It is a figure which shows the structure of the control device 13 when the control device 13 is realized by software and general-purpose hardware.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Hereinafter, a plurality of embodiments will be described, but it is planned from the beginning of the application to appropriately combine the configurations described in the respective embodiments. The same or corresponding parts in the drawings are designated by the same reference numerals and the description thereof will not be repeated.

Embodiment 1.
FIG. 1 is a diagram showing the configuration of the laser light generator 200 of the first embodiment. The laser light generator 200 includes an LD drive power supply device 100, an LD 20, a processing head 53, and a condensing unit 52. Hereinafter, the LD drive power supply device may be simply referred to as a “power supply device”.

The LD20 is arranged between the node ND6 and the node ND4 (ground power supply or reference power supply of the LD20). The LD 20 emits a laser by a current supplied from the LD drive power supply device 100. LD20 includes at least one LD alone. When the LD 20 includes a plurality of LD units, the plurality of LD units are connected in series in the forward direction, connected in parallel, or connected in series and in parallel between the anode terminal and the cathode terminal of the LD 20. For high power laser devices, at least one LD20 is used.

The light collecting unit 52 collects the laser light of the LD 20 and transmits it to the processing head 53. As the light collecting unit 52, an optical fiber, a prism, a mirror, an optical coupling element, or an optical amplifier can be used.

The power supply device 100 includes a power supply 10, a smoothing circuit 104, a current path switching circuit 105, and a control device 13.

The power supply 10 converts the AC power supplied from the AC power supply 400 into DC power and supplies a constant current to the LD 20. The AC power supply 400 supplies, for example, an AC voltage of 100V to 480V to the power supply 10. The AC power supply 400 is, for example, a three-phase AC power supply or a single-phase AC power supply. The AC power source 400 is, for example, a commercial AC power source or a private power generator.

The current detector 11 is arranged between the node ND5 and the node ND6, or between the node ND8 and the node ND4. The current detector 11 detects the current flowing from the power supply device 100 to the LD 20. As the current detector 11, a series resistance element (shunt resistance element), a CT (Current Transformer), a Hall current sensor, or the like can be used. As the current detector 11, an IC (Integrated Circuit) for current detection may be used. By using a general-purpose component as the current detector 11, it is possible to reduce the cost.

The power supply 10 includes a rectifying unit 101, a conversion unit 102, and a rectifying circuit 103.
The rectifying unit 101 rectifies the AC power supplied from the AC power supply 400. The rectifying unit 101 includes a rectifying circuit 1 and a smoothing capacitor 2. The rectifier circuit 1 is arranged between the node ND1 and the node ND2. The rectifier circuit 1 rectifies the AC power supplied from the AC power supply 400. The rectifying unit 101 may be a power factor improving circuit capable of improving the power factor. The smoothing capacitor 2 is arranged between the node ND1 and the node ND2. The smoothing capacitor 2 is connected in parallel to the rectifier circuit 1.

The conversion unit 102 converts the power output from the rectifying unit 101 into AC power by operating the full bridge inverter. The conversion unit 102 is an isolated power conversion unit. The conversion unit 102 includes a voltage conversion circuit 3 and a transformer 4. The voltage conversion circuit 3 is arranged between the node ND1 and the node ND2. The voltage conversion circuit 3 converts the voltage rectified by the rectifying unit 101 into an AC voltage based on the drive signal DR output from the control device 13. The voltage conversion circuit 3 is composed of, for example, a full bridge circuit. Instead of the full bridge circuit, the voltage conversion circuit 3 is a general DC-DC converter system such as a forward system, a flyback system, a push-pull system, or a half-bridge system, depending on the amount of conversion power. The circuit may be of the type that optimizes efficiency and cost. The voltage conversion circuit 3 may be a composite form of these circuit methods. The conversion unit 102 may include both an isolated power conversion circuit and a non-isolated power conversion circuit such as a chopper system, and may use them in combination. When used in combination, it may be easier to adjust the boost ratio. The voltage conversion circuit 3 includes a plurality of switching elements. The transformer 4 converts the AC voltage converted by the voltage conversion circuit 3 into a voltage having a specific value corresponding to the winding ratio. The output current of the transformer 4 is adjusted by the ratio of the on-time to the switching cycle of the plurality of switching elements constituting the voltage conversion circuit 3.

The rectifier circuit 103 is arranged between the node ND3 (first output terminal of the power supply 10) and the node ND7 (second output terminal of the power supply 10). The rectifier circuit 103 rectifies the AC voltage output from the conversion unit 102. The rectifier circuit 103 is, for example, a full-wave rectifier circuit composed of four diodes. The configuration of the rectifier circuit 103 is not limited to that shown in FIG. The rectifier circuit 103 may be configured by a switching element capable of reducing loss instead of the diode.

A non-isolated DC-DC converter such as a chopper circuit system may be used for the conversion unit 102 and the rectifier circuit 103. The non-isolated DC-DC converter can realize high-efficiency conversion at low cost as compared with the isolated DC-DC converter.

The smoothing circuit 104 smoothes the voltage rectified by the rectifier circuit 103. The smoothing circuit 104 includes a reactor circuit 30 and a smoothing capacitor 6.

The reactor circuit 30 is arranged between the node ND3 (first output terminal of the power supply 10) and the node ND5 (output terminal of the reactor circuit 30). The reactor circuit 30 is connected to the power supply 10.

When the inductance value of the reactor circuit 30 is large, the amount of current ripple to the LD 20 can be reduced, so that the fluctuation of the output amount of the laser beam becomes small. As a result, a stable laser beam output can be obtained. However, since the inductance value of the reactor circuit 30 is large, it takes time to change to a desired current value, so that the rise time and the fall time of the current become long. For example, in a laser device including a laser processing machine, there is a case where it is desired to change the amount of laser light output instantaneously by turning on or off the laser light output. When the inductance value of the reactor circuit 30 is large, the laser beam output amount cannot be changed instantaneously.

When the inductance value of the reactor circuit 30 is small, the amount of current ripple to the LD 20 becomes large, so that a stable laser beam output cannot be obtained. However, since the inductance value is small, a desired laser beam output can be obtained in a short time. When the inductance value of the reactor circuit 30 is small, the amount of current ripple to the LD 20 becomes large, but by controlling the current path switching circuit 105 so that only the current when it becomes large flows to the LD 20, a large pulsed laser is used. Light output can be obtained. As a result, for example, in a laser processing machine or the like, high-precision processing becomes possible.

In the present embodiment, the reactor circuit 30 has a variable inductance value in order to take advantage of the magnitude of the inductance of the reactor circuit 30 described above. If you want to obtain a stable laser beam output, increase the inductance value. On the other hand, when it is desired to obtain a high-output laser beam with a short pulse, or when it is desired to obtain a laser beam output with a high-speed rising edge, the inductance value is reduced.

The reactor core in the reactor circuit 30 may be an air core or a magnetic material such as ferrite. When a large current flows through the reactor in the reactor circuit 30, an edgewise coil or an entirely molded reactor may be used. An edgewise coil is a coil in which a flat wire is wound in the edgewise direction. Since the edgewise coil has a one-layer structure, the winding has a high heat dissipation property as compared with a reactor having a round winding structure and a multi-layer structure. Since the entire molded reactor can dissipate heat from the molded portion, it has higher heat dissipation than the unmolded reactor. By using an edgewise coil or a reactor molded entirely, it is possible to suppress the temperature rise of each reactor. Therefore, it is possible to reduce the size of the cooling mechanism (for example, heat dissipation fins, water cooling mechanism, etc.) required to dissipate heat from the reactor, and to simplify the cooling method (for example, from forced air cooling to natural air cooling), thus reducing the number of cooling members. be able to.

FIG. 2 is a diagram showing the configuration of the reactor circuit 30 of the first embodiment. The reactor circuit 30 includes two types of

reactors

5a and 5b having different inductance values from each other, and an inductance value switching switch 14.

The reactor 5b connected in series and the inductance value switching switch 14 are arranged between the node ND3 and the node ND5. The reactor 5a is arranged between the node ND3 and the node ND5.

The inductance value of the reactor 5a is larger than the inductance value of the reactor 5b. The reactor 5b may be only wiring. This is because the wiring has a parasitic inductance component. Which of the reactor 5b and the inductance value switching switch 14 may be arranged on the node ND3 side or the node ND5 side.

The inductance value switching switch 14 is turned on / off by the gate drive signal GT2 from the control device 13. When the inductance value switching switch 14 is turned off, only the reactor 5a is connected between the node ND3 and the node ND5, so that the inductance value of the reactor circuit 30 becomes large. When the inductance value switching switch 14 is on, the reactor 5a and the reactor 5b are connected in parallel between the node ND3 and the node ND5, so that the inductance value of the reactor circuit 30 becomes small.

Again, referring to FIG. 1, the smoothing capacitor 6 is arranged between the node ND5 and the node ND7.

The current path switching circuit 105 is arranged between the nodes ND5 and ND8 and the LD20. The current path switching circuit 105 is configured to switch whether or not to supply the current output from the reactor circuit 30 to the LD 20.

FIG. 3 is a diagram showing the configuration of the current path switching circuit 105.
As shown in FIG. 3, the current path switching circuit 105 includes a path switching switch 12 connected in parallel to the LD 20. The route switching switch 12 is, for example, an N-type MOSFET.

The route switching switch 12 is turned on / off by the gate drive signal GT1 from the control device 13. When the path switching switch 12 is off, the current output from the reactor circuit 30 flows through the LD 20. When the path switching switch 12 is on, the current output from the reactor circuit 30 does not flow through the LD 20 but flows through the path switching switch 12. That is, in the power supply device 100, the current path through which the output current of the reactor circuit 30 flows is switched by turning on / off the path switching switch 12 when the laser pulse is driven. By instantly switching the current path, the current to the LD 20 can be turned down or up at high speed.

FIG. 4 is a diagram showing another configuration of the current path switching circuit 105.
As shown in FIG. 4, the route switching switch 12 is connected in series to the LD 20. The route switching switch 12 is, for example, an N-type MOSFET.

The route switching switch 12 is turned on / off by the gate drive signal GT1 from the control device 13. When the path switching switch 12 is on, the current output from the reactor circuit 30 flows through the LD 20. When the path switching switch 12 is off, no current flows from the reactor circuit 30. That is, in the power supply device 100, a current can be passed to the LD 20 by turning on / off the path switching switch 12 when the laser pulse is driven. Further, by adjusting the gate applied voltage amount of the path switching switch 12, it is possible to adjust the resistance value of the path switching switch 12 and change the amount of current flowing through the LD 20.

When the drive current of the LD 20 is large, a snubber circuit may be connected to the path switching switch 12 in order to suppress the surge voltage generated when the path switching switch 12 is turned on / off. Instead of the snubber circuit, a circuit or a Zener diode that starts when the voltage exceeds a certain value may be provided. A resistance element for power consumption or current limiting may be connected in series with the path switching switch 12.

A smoothing capacitor may be provided in parallel with the path switching switch 12. By providing the smoothing capacitor, the rising and falling speeds of the drive current of the LD20 are lowered, so that the response speed of the laser beam output of the LD20 may be lowered. However, since the current output from the power supply 10 can be smoothed, the current supplied to the LD 20 can be smoothed and the laser light output of the LD 20 can be further stabilized. Therefore, if the response speed of the laser beam output is not required, it is better to provide a smoothing capacitor. In order to further smooth the current output from the power supply 10, it is necessary to increase the capacity of the smoothing capacitor. To increase the capacity of the smoothing capacitor, it is conceivable to increase the capacity of a single smoothing capacitor or to use a plurality of smoothing capacitors connected in parallel. However, when the response speed of the laser light output is to be obtained, if the capacity of the smoothing capacitor is made too large, the response of the laser light output is large because the capacity of the smoothing capacitor is large even if the variable inductance value of the reactor circuit 30 is minimized. The speed cannot be increased. In order to smooth, that is, to reduce the current ripple, it is desirable to minimize the capacity of the smoothing capacitor and increase the maximum value of the variable inductance value of the reactor circuit 30.

Next, the operation of the current path switching circuit 105 will be described.
When the power supply 10 is being driven and a current is flowing through the reactor circuit 30, the control device 13 controls the on / off of the path switching switch 12 by the gate drive signal GT1 to output the output from the reactor circuit 30. It is possible to decide whether or not to pass the current through the LD20. The current path switching circuit 105 raises or lowers the drive current of the LD 20 according to the gate drive signal GT1.

When the drive current of the LD 20 is large, a snubber circuit may be provided in parallel with the path switching switch 12 in order to suppress the surge voltage generated when the path switching switch 12 is turned off. As the snubber circuit, for example, an RCD snubber circuit configured by connecting a diode in series to a resistance element and a capacitor connected in parallel may be used.

In a large device such as a laser processing device, the current path switching circuit 105 and the LD 20 are often separated from each other. In such a case, the wiring between the current path switching circuit 105 and the LD 20 becomes long, and it may be difficult to appropriately control the drive current of the LD 20 due to the parasitic inductance of the wiring. In order to reduce the parasitic inductance value of the wiring between the current path switching circuit 105 and LD20, a current path switching circuit 105 is installed near the LD20 so that the wiring between the current path switching circuit 105 and LD20 is shortened. You may. Further, wiring may be performed so that the loop area of the wiring between the current path switching circuit 105 and the LD 20 is minimized so that the effect of canceling the mutual inductance of the wiring is large.

In the laser light generator 200 configured in this way, the laser is emitted from the LD 20 by supplying a current from the power supply device 100 to the LD 20. The laser emitted from the LD 20 is transmitted to the processing head 53 by the condensing unit 52 and the like, and is condensed on the work 300 by the lens 54 in the processing head 53. As a result, the work 300 is cut. Since it is necessary to move the laser condensing position on the work 300 when processing the work 300, the work 300 is installed on a work moving mechanism (not shown) for moving the work 300, or the work 300 is processed by the laser light generator 200. It is assumed that a head moving mechanism (not shown) for moving the head 53 is provided.

As the switch used in the conversion unit 102, the smoothing circuit 104, and the current path switching circuit 105, it is preferable to use a switching element such as an IGBT (Insulated Gate Bipolar Transistor) or a MOSFET (Metal Oxide Semiconductor Field Effect Transistor). The switching element may be made of a material of Si (Silicon). On the other hand, when the switching element is made of a material of SiC (Silicon Carbide) or GaN (Gallium Nitride), switching loss and conduction loss can be suppressed, so that the efficiency of the power supply device 100 can be improved and lowered. Loss can be achieved. The switch may be configured by a relay or an analog switch. In this case, there is an advantage that an elaborate gate drive circuit becomes unnecessary.

The control device 13 includes a machining command output unit 81, a switch control unit 82, and a current control unit 83.

The machining command output unit 81 outputs a current command value ID, which is a machining command.
The switch control unit 82 controls the on / off of the gate drive signal GT1 for controlling the on / off of the path switching switch 12 in the current path switching circuit 105 and the inductance value switching switch 14 in the reactor circuit 30. The drive signal GT2 is output.

The current control unit 83 generates a drive signal DR for controlling the operation of the voltage conversion circuit 3 so that the current I supplied to the LD 20 indicated by the detection signal of the current detector 11 matches the current command value ID. do. The on / off duty ratio of the drive signal DR is controlled so that there is no deviation between the current I and the current command value ID.

The control device 13 further includes a communication circuit (not shown). The communication circuit sends and receives signals to and from other components via the communication line.

FIG. 5 is a timing chart showing the operation of the laser light generator 200 of the first embodiment. In FIG. 5, in order from the top, the current command value ID input to the current control unit 83, the gate drive signal GT1 of the path switching switch 12, the reactor current in which the energy stored in the reactor 5a is released, and the inductance value switching. The gate drive signal GT2 of the switch 14, the inductance current in which the energy stored in the reactor 5b is released, and the drive current of the LD 20 are shown.

On the time axis in FIG. 5, in the section (a), the mode of the laser light generator 200 is set to mode A, and the laser light generator 200 operates as follows.

The switch control unit 82 sets the gate drive signal GT1 to a high level and the gate drive signal GT2 to a low level. Since the gate drive signal GT1 is set to a high level, the route switching switch 12 is turned on. As a result, no current flows through the LD20. Since the gate drive signal GT2 is set to the low level, the inductance value switching switch 14 is turned off. As a result, in the reactor circuit 30, a current flows only in the reactor 5a, so that a constant current ripple occurs. However, since the inductance value of the reactor 5a is large, the current ripple amount of the output current of the reactor 5a is small.

In the section (b), the mode of the laser light generator 200 is set to mode B, and the laser light generator 200 operates as follows.

The machining command output unit 81 sets the current command value ID to Ia. The switch control unit 82 sets the gate drive signal GT1 at the low level and maintains the gate drive signal GT2 at the low level. Since the gate drive signal GT1 is set to the low level, the route switching switch 12 is turned off. As a result, a current flows through the LD 20. When a stable constant current is required, the mode of the laser beam generator 200 is maintained in mode B.

In the section (c), the mode of the laser light generator 200 is set to mode C, and the laser light generator 200 operates as follows.

The switch control unit 82 sets the gate drive signal GT1 to a high level. Since the gate drive signal GT1 is set to a high level, the route switching switch 12 is turned on. As a result, no current flows through the LD20.

In the section (d), the mode of the laser light generator 200 is set to mode D, and the laser light generator 200 operates as follows.

The switch control unit 82 sets the gate drive signal GT2 to a high level. Since the gate drive signal GT2 is set to a high level, the inductance value switching switch 14 is turned on. As a result, in the reactor circuit 30, a current flows through the reactor 5a and the reactor 5b. Since the inductance value of the reactor 5b is set smaller than the inductance value of the reactor 5a, the current ripple amount of the output current of the reactor 5b is large and the current peak value is high.

In the section (e), the machining command output unit 81 sets the current command value ID to Ib. The switch control unit 82 sets the gate drive signal GT1 to a low level. Since the gate drive signal GT1 is set to the low level, the route switching switch 12 is turned off. As a result, a current flows through the LD 20. The section (e) is a period in which the sum of the output current of the reactor 5a and the output current of the reactor 5b, which is the current output from the reactor circuit 30, is equal to or more than the specified value TH. This period is the time at which the output current of the reactor 5b peaks and the time near that time. As a result, the current can be passed through the LD 20 only during the period when the current output from the reactor circuit 30 is large.

As described above, during the period (e), a laser beam output with a high peak can be obtained from the LD20 with a short pulse. Since it is a short pulse, the heat generation of the LD 20 can be suppressed. Conventionally, when the laser irradiates the work for a long time, the heat load on the work side increases. As a result, there are cases where the laser processing accuracy deteriorates and the processing state of the laser processing cut surface deteriorates. In the present embodiment, the heat load on the work can be locally applied by the laser light output having a high peak with a short pulse, so that the above problem can be reduced.

Next, a simulation result showing the relationship between the inductance value of the reactor circuit 30 and the current flowing through the LD 20 will be described.

FIG. 6A is a diagram showing the current flowing through the LD 20 when the inductance value of the reactor circuit 30 is 10 μH. The peak value of the current flowing through the LD 20 is 254 A. Assuming that the difference between the maximum and minimum currents is the ripple amount, the ripple amount at this time is Δ7A.

FIG. 6B is a diagram showing the current flowing through the LD 20 when the inductance value of the reactor circuit 30 is 1 μH. The peak value of the current flowing through the LD 20 is 282A. The amount of ripple is Δ66A.

FIG. 6C is a diagram showing the current flowing through the LD 20 when the inductance value of the reactor circuit 30 is 0.1 μH. The peak value of the current flowing through the LD 20 is 498 A. The amount of ripple is Δ488A.

It can be seen that when the inductance value of the reactor circuit 30 is 0.1 μH, the current peak value can be doubled as compared with the case where the inductance value is 10 μH. In this way, when it is desired to obtain a stable laser beam output, the inductance value of the reactor circuit 30 may be increased. On the other hand, when it is desired to obtain a laser beam output having a high peak, the inductance value of the reactor circuit 30 may be reduced. Further, the current path switching circuit 105 may be used to control the path switching switch 12 by the gate drive signal GT1 so that the current flows to the LD 20 only during the high peak current period.

Embodiment 2.
FIG. 7 is a diagram showing the configuration of the reactor circuit 30c according to the second embodiment.

The reactor circuit 30c includes two

reactors

5a and 5c having the same inductance value and one inductance value switching switch 14.

A reactor 5c connected in series and an inductance value switching switch 14 are arranged between the node ND3 and the node ND5. A reactor 5a is arranged between the node ND3 and the node ND5. The switch control unit 82 can increase the inductance value of the reactor circuit 30a by turning off the inductance value switching switch 14 so that the current flows only through the reactor 5a. The switch control unit 82 can reduce the inductance value of the reactor circuit 30c by turning on the inductance value switching switch 14 so that a current flows through the reactor 5a and the reactor 5c.

In the present embodiment, the number of types of parts can be reduced by using two reactors having the same inductance value. Either the reactor 5c or the inductance value switching switch 14 may be arranged on the node ND3 side or the node ND5 side.

Embodiment 3.
FIG. 8 is a diagram showing the configuration of the reactor circuit 30d according to the third embodiment.

The reactor circuit 30d includes a reactor 5c and an inductance value switching switch 14. The midpoint of the reactor 5c branches and is connected to the inductance value switching switch 14. The switch control unit 82 can change the inductance value of the reactor circuit 30d by controlling the on / off of the inductance value switching switch 14.

In the present embodiment, the number of reactors in the reactor circuit 30d can be one.

Embodiment 4.
FIG. 9 is a diagram showing the configuration of the reactor circuit 30e according to the fourth embodiment.

The reactor circuit 30e includes two

reactors

5a and 5b having different inductance values and two inductance

value switching switches

14a and 14b. The magnitude of the inductance value of the

reactors

5a and 5b may be either.

A reactor 5b and an inductance value switching switch 14b connected in series are arranged between the node ND3 and the node ND5. A reactor 5a connected in series and an inductance value switching switch 14a are arranged between the node ND3 and the node ND5. The switch control unit 82 controls the on / off of the inductance value switching switch 14a by the gate drive signal GT2. The switch control unit 82 controls the on / off of the inductance value switching switch 14b by the gate drive signal GT3. Since both current paths of the

reactors

5a and 5b can be turned off by the inductance

value switching switches

14a and 14b, it is possible to control the LD20 on / off. Either the

reactors

5a and 5b and the inductance

value switching switches

14a and 14b may be arranged on the node ND3 side or the node ND5 side.

Embodiment 5.
FIG. 10 is a diagram showing the configuration of the laser light generator 200a according to the fifth embodiment. The difference between the laser light generator 200a of the fifth embodiment and the laser light generator 200 of the first embodiment is that the laser light generator 200a of the fifth embodiment replaces the smoothing circuit 104 with the smoothing circuit 104a. It is a point to prepare.

The smoothing circuit 104a includes a reactor circuit 30a having an overvoltage prevention function and a smoothing capacitor 6 similar to that of the first embodiment.

The reactor circuit 30a includes a reactor 5b, a reactor 5a, an inductance value switching switch 14, and an overvoltage prevention circuit 15.

Similar to the first embodiment, the reactor 5b connected in series and the inductance value switching switch 14 are arranged between the node ND3 and the node ND5. Similar to the first embodiment, the reactor 5a is arranged between the node ND3 and the node ND5.

The overvoltage prevention circuit 15 is arranged between the node ND8 between the reactor 5b and the inductance value switching switch 14 and the node ND7. The overvoltage protection circuit 15 is composed of a Zener diode or a switching element. If an overcurrent flows only with the switching element, a resistance element may be directly connected to the switching element.

When the voltage across the inductance value switching switch 14 exceeds a certain voltage VT, the overvoltage prevention circuit 15 is turned on. As a result, the electric charge accumulated in the reactor 5b can be released. As a result, the voltage applied across the inductance value switching switch 14 can be suppressed to the withstand voltage or less, so that the failure of the inductance value switching switch 14 can be prevented.

Similarly, when the inductance value switching switch 14 is arranged on the node ND3 side and the reactor 5b is arranged on the node ND5 side, the overvoltage prevention circuit 15 is arranged between the inductance value switching switch 14 and the reactor 5b. Thereby, the voltage applied to both ends of the inductance value switching switch 14 can be suppressed to the withstand voltage or less.

Embodiment 6.
FIG. 11 is a diagram showing the configuration of the laser light generator 200b according to the sixth embodiment. The difference between the laser light generator 200b of the sixth embodiment and the laser light generator 200 of the first embodiment is that the laser light generator 200b of the fifth embodiment replaces the smoothing circuit 104 with the smoothing circuit 104b. It is a point to prepare.

The smoothing circuit 104b includes a reactor circuit 30b, a smoothing capacitor 6a, and a smoothing capacitor 6b.

The reactor circuit 30b includes a reactor 5a, a reactor 5b, an inductance value switching switch 14a, an inductance value switching switch 14b, an overvoltage prevention circuit 15a, and an overvoltage prevention circuit 15b.

The smoothing capacitor 6a is arranged between the node ND 9 and the node ND 7. The smoothing capacitor 6b is arranged between the node ND8 and the node ND7. The reactor 5b is arranged between the node ND3 and the node ND8. The reactor 5a is arranged between the node ND3 and the node ND9. The inductance value switching switch 14b is arranged between the node ND8 and the node ND5. The inductance value switching switch 14a is arranged between the node ND 9 and the node ND 5. The overvoltage prevention circuit 15b is arranged between the node ND8 and the node ND7. The overvoltage prevention circuit 15a is arranged between the node ND 9 and the node ND 7. The

overvoltage prevention circuits

15a and 15b are configured by a switching element, a Zener diode, or the like.

When two or more sets of a reactor, a smoothing capacitor, and a switch are provided in this way, it is possible to supply a stable current with a small amount of current ripple and to increase the peak current value.

For example, the inductance value of the reactor 5a can be made larger than the inductance value of the reactor 5b, and the capacity of the smoothing capacitor 6a can be made larger than the capacity of the smoothing capacitor 6b.

If a steep rise of the current is desired, turn on the inductance value switching switch 14b and let the current flow through the reactor 5b. In this case, since the capacity of the smoothing capacitor 6b is small, the output current can be increased to a desired value in a short charging time.

On the other hand, when a stable output current during normal operation is desired, the inductance value switching switch 14a is turned on and a current is passed through the reactor 5a. In this case, the current ripple of the output current can be suppressed.

The node ND8 between the reactor 5b and the inductance value switching switch 14b and the node ND9 between the reactor 5a and the inductance value switching switch 14a are provided with

overvoltage prevention circuits

15b and 15a for overvoltage prevention, respectively. When the voltage across the inductance value switching switch 14a becomes a certain voltage VT or higher, the overvoltage prevention circuit 15a is turned on. When the voltage across the inductance value switching switch 14b becomes a certain voltage VT or higher, the overvoltage prevention circuit 15b is turned on. This makes it possible to prevent the inductance

value switching switches

14b and 14a from being destroyed.

Similarly, when the inductance value switching switch 14 is arranged on the node ND3 side and the reactor 5 is arranged on the node ND5 side, the overvoltage prevention circuit 15 is arranged between the inductance value switching switch 14 and the reactor 5. , The voltage applied to both ends of the inductance value switching switch 14 can be suppressed to the withstand voltage or less.

Embodiment 7.
The inductance value L of the reactor is expressed by the following equation.

L = K × μ × π × a ² × n ² / b ... (2)
K is the Nagaoka coefficient, μ is the magnetic permeability, a is the reactor radius, b is the reactor length, and n is the number of turns of the reactor.

12 (a) and 12 (b) are diagrams for explaining the first method of mechanically changing the inductance value of the reactor. From the equation (2), the inductance value can be changed by changing the length b of the reactor RT. As shown in FIGS. 12A and 12B, the inductance value can be changed by mechanically changing the length b of the reactor RT. For example, both ends of the reactor RT are fixed with

insulators

251a and 251b, and the distance between the

insulators

251a and 251b at both ends is mechanically adjusted by using a ball screw 253 and a motor 254 (stepping motor, etc.) to set the length b of the reactor RT. Can be changed.

FIGS. 12 (c) and 12 (d) are diagrams for explaining a second method of mechanically changing the inductance value of the reactor. As shown in FIGS. 12 (c) and 12 (d), the inductance value can be changed by fixing one end of the reactor RT and changing the position of the other end.

FIGS. 12 (e) and 12 (f) are diagrams for explaining a third method of mechanically changing the inductance value of the reactor. When the reactor is composed of two subreactors RTa and RTb, the inductance value can be changed by changing the distance between the respective subreactors RTa and RTb. This is due to the influence of each leakage flux. In FIGS. 12 (e) and 12 (f), the inductance value is changed by changing the positions of the

bases

261a and 261b fixing the subreactors RTa and RTb by the motor 254 and the ball screw 253.

FIG. 13 is a diagram showing a change in the inductance value with respect to the length of the air core coil. FIG. 13 shows the coil length dependence of the inductance value when the coil radius is 50 mm and the number of turns is 10 turns. By increasing the length of the coil to 8 times from 50 mm to 400 mm, the inductance value of the coil can be increased from 10 μH to 2.3 μH.

The above method of mechanically changing the inductance value of the reactor can be used even when the inductance value of the reactor needs to be adjusted accurately. For example, it is necessary to adjust the inductance value of the reactor in order to match the current value accurately, but in the usual reactor manufacturing method, the inductance variation is ± 5% or more. In such a case, it is possible to reduce the variation in the inductance value at the time of mass production by manually adjusting the length of the reactor and the distance between the reactors at the time of manufacturing instead of the motor 254.

Although the air core reactor is shown in FIGS. 12 (a) to 12 (f), the reactor is not limited to the air core and may be made of a magnetic material such as ferrite. In this case, a large inductance value can be obtained.

When the inductance switching of the reactor circuit 30 by the inductance value switching switch 14 and the inductance switching of the reactor circuit 30 by mechanical means as shown in FIGS. 12A to 12F are used in combination, the inductance becomes higher. The range of values can be expanded.

After initializing the inductance of the reactor circuit 30 by manually adjusting the length of the reactor and the distance between the reactors, the inductance value switching switch 14 switches the inductance of the reactor circuit 30. Thereby, the range of the inductance value can be expanded.

Embodiment 8.
FIG. 14 is a diagram showing the configuration of the laser processing apparatus of the eighth embodiment. The laser processing device includes a laser light generator 51, a condensing unit 52, a processing head 53, a lens 54, and a positioning device 55. As the light collecting unit 52, an optical fiber, a prism, a mirror, an optical coupling element, or an optical amplifier can be used.

The laser light generator 51 is one of the laser light generators of the above-described first to eighth embodiments. The laser light generator 51 outputs the laser light β having a small ripple.

The condensing unit 52 transmits the laser light β output from the laser light generator 51 to the processing head 53.

The processing head 53 vertically irradiates the surface of the object 56 with the laser beam β.
The lens 54 is provided between the processing head 53 and the object 56. The lens 54 is focused on the surface of the object 56.

The object 56 is mounted on the positioning device 55. By moving the object 56 in the horizontal and vertical directions, the positioning device 55 can focus the workpiece position on the surface of the object 56 on the lens 54. The laser light β emitted from the laser light generator 51 is irradiated to the processed position of the object 56 via the condensing unit 52, the processing head 53, and the lens 54, and the object 56 is processed.

In the eighth embodiment, since the laser light generators of the above-mentioned embodiments 1 to 7 are used, the ripple amount required at the time of laser processing can be controlled. As a result, the object 56 can be irradiated with a stable laser beam β having a small ripple. As a result, it is possible to improve the flatness accuracy of the machined cross section during laser machining. Further, since the object 56 can be irradiated with a short pulse laser at a high peak, it is possible to suppress processing burrs and the like during laser processing.

Embodiment 9.
The control device 13 is realized by dedicated hardware such as a dedicated processing circuit, or is realized by software and general-purpose hardware.

When the control device 13 is configured by dedicated hardware, the dedicated processing circuit includes a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), and an FPGA (Field Programmable). Gate Array) or a combination of these is applicable.

FIG. 15 is a diagram showing the configuration of the control device 13 when the control device 13 is realized by software and general-purpose hardware.

The control device 13 is composed of a processor 131 and a storage device 132 connected to the bus 133.

Each function of the control device 13 is realized by software, firmware, or a combination thereof. The software or firmware is written as a program and stored in the storage device 132. The processor 131 reads and executes the program stored in the storage device 132. It can be said that these programs cause the computer to execute the procedure and the method for realizing each function of the control device 13.

The storage device 132 corresponds to a semiconductor memory such as RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EPROM (Erasable Programmable Read Only Memory), or EEPROM (Electrically Erasable Programmable Read Only Memory (registered trademark)). do. The semiconductor memory may be a non-volatile memory or a volatile memory. In addition to semiconductor memory, the storage device includes magnetic disks, flexible disks, optical disks, compact disks, mini disks, and DVDs (Digital Versatile Disc).

It is also planned that the embodiments disclosed this time will be appropriately combined and implemented within a technically consistent range. And it should be considered that the embodiments disclosed this time are exemplary in all respects and not restrictive. The scope of the present invention is shown by the claims rather than the description of the embodiments described above, and is intended to include all modifications within the meaning and scope equivalent to the claims.

1,103 rectifier circuit, 2,6,6a, 6b smoothing capacitor, 3 voltage conversion circuit, 4 transformer, 5a, 5b, 5c, RT reactor, 10 power supply, 11 current detector, 12, 12a path switching switch, 13 Control device, 14, 14a, 14b Invertance value changeover switch, 15, 15a, 15b Overvoltage prevention circuit, 30, 30a, 30b, 30c, 30d, 30e reactor circuit, 51, 200, 200a, 200b, 200c Laser light generator , 52 Condensing unit, 53 processing head, 54 lens, 55 positioning device, 56 object, 81 processing command output unit, 82 switch control unit, 83 current control unit, 100 LD drive power supply unit, 101 rectifier unit, 102 conversion Unit, 104,104a, 104b smoothing circuit, 105,105a current path switching circuit, 131 processor, 132 storage device, 133 bus, 251a, 251b insulator, 253 ball screw, 254 motor, 261a, 261b stand, 300 work, 400 AC power supply, RTa, RTb subreactor.

Claims

With a laser diode
A power supply that supplies current,
A reactor circuit that is connected to the power supply and has a variable inductance value,
A current path switching circuit configured to switch whether or not to supply the current output from the reactor circuit to the laser diode, and a current path switching circuit.
A laser light generator including a control device for controlling the current path switching circuit and setting an inductance value of the reactor circuit.
In the control device, when the mode of the laser light generator is the first mode, the inductance value of the reactor circuit is set small, and the current path is switched so that the current output from the reactor circuit flows to the laser diode. The laser light generator according to claim 1, which controls a circuit.
In the control device, when the mode of the laser light generator is the second mode, the inductance value of the reactor circuit is set large, and the reactor is used only during the period when the current output from the reactor circuit becomes a specified value or more. The laser light generator according to claim 1, wherein the current path switching circuit is controlled so that the current output from the circuit flows through the laser diode.
The reactor circuit is
A first reactor and an inductance value switching switch connected in series between a first node which is a first output terminal of the power supply and a second node which is an output terminal of the reactor circuit.
The laser light generator according to any one of claims 1 to 3, further comprising a second reactor disposed between the first node and the second node.
The reactor circuit further
The laser light generator according to claim 4, further comprising an overvoltage protection circuit arranged between the third node between the first reactor and the inductance value switching switch and the reference power supply of the laser diode. ..
The laser light generator according to any one of claims 4 to 5, wherein the inductance value of the first reactor is smaller than the inductance value of the second reactor.
The laser light generator according to any one of claims 4 to 5, wherein the inductance value of the first reactor is equal to the inductance value of the second reactor.
The reactor circuit is
A first reactor and a first inductance value switching switch connected in series between a first node which is a first output terminal of the power supply and a second node which is an output terminal of the reactor circuit. When,
The laser beam according to any one of claims 1 to 3, further comprising a second reactor and a second inductance value switching switch arranged between the first node and the second node. Generator.
The reactor circuit further
A third node between the first reactor and the first inductance value switching switch, and a first overvoltage protection switch arranged between the reference power supply of the laser diode.
8. The eighth aspect of the present invention, which includes a fourth node between the second reactor and the second inductance value switching switch, and a second overvoltage protection switch arranged between the reference power supply and the reference power supply. Laser light generator.
The reactor circuit is
A reactor arranged between the first node, which is the first output terminal of the power supply, and the second node, which is the output terminal of the reactor circuit,
The laser light generator according to any one of claims 1 to 3, further comprising an inductance value switching switch arranged between the midpoint of the reactor and the second node.
The reactor circuit is
With the reactor,
The laser light generator according to any one of claims 1 to 3, further comprising a motor for changing the length of the reactor.
The laser light generator according to any one of claims 1 to 3, wherein the current path switching circuit includes a path switching switch connected in parallel to the laser diode.
The laser light generator according to any one of claims 1 to 3, wherein the current path switching circuit includes a path switching switch connected in series with the laser diode.
The laser light generator according to any one of claims 1 to 13.
A laser processing apparatus including a processing head that irradiates the surface of an object with a laser beam output from the laser beam generator.