Laser device, laser machining apparatus, and method for controlling output of laser device

A laser device, including multiple laser modules, includes a plurality of drive power units that drive the laser modules, a plurality of output detection units that detect laser outputs from the laser modules, and output detected values as first output signals, a coupled output detection unit that detects a total laser output after coupling of a plurality of the laser outputs, and outputs a detected value as a second output signal, a computing unit that sets multiple output correction factors for correspondingly controlling the laser modules using the plurality of first output signals and the second output signal, and a control unit that controls the plurality of drive power units using the multiple output correction factors. The multiple output correction factors are each set to allow the total laser output to be maintained at a constant value.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is based on PCT filing PCT/JP2018/017671, filed May 7, 2018, the entire contents of which are incorporated herein by reference.

FIELD

The present invention relates to a laser device that controls an output of a laser beam, a laser machining apparatus, and a method for controlling an output of a laser device.

BACKGROUND

Some of laser devices that output a laser beam, each couple laser beams output from multiple laser modules and output the resultant laser beam. The laser device described in Patent Literature 1 includes an optical coupling unit that couples laser beams output from multiple laser modules, first light detection units that each detect a laser output value at a corresponding one of the laser modules, and a second light detection unit that detects a laser output value at the optical coupling unit. The laser device described in Patent Literature 1 determines whether there is fault or degradation in the laser device based on detection results of the first light detection units and of the second light detection unit.

CITATION LIST

Patent Literature

SUMMARY

Technical Problem

The laser device of Patent Literature 1 listed above is not capable of independently controlling the individual laser modules, and therefore, upon a decrease in the coupled laser output, restores the coupled laser output that is output from the laser device by increasing the output of each of the multiple laser modules at a fixed rate to restore the coupled laser output to the previous output value. This increases the output of a degraded laser module also at a fixed rate, thereby presenting a problem of further degradation of the degraded laser module.

The present invention has been made in view of the foregoing, and it is an object of the present invention to provide a laser device capable of reducing further degradation of a degraded laser module while maintaining the laser output value after coupling of the laser beams within an acceptable range.

Solution to Problem

An aspect of the present invention is directed to a laser device including a plurality of laser modules, that includes a plurality of drive power units that drive the laser modules, a plurality of laser output detection units that detect laser outputs from the laser modules, and output detected values as first output signals, and a coupled output detection unit that detects a total laser output after coupling of the laser outputs, and outputs a detected value as a second output signal. The laser device also includes a computing unit that sets a plurality of output correction factors for correspondingly controlling the laser modules using the plurality of first output signals and the second output signal, and a control unit that controls the plurality of drive power units using the multiple output correction factors. The multiple output correction factors are each set to allow the total laser output to be maintained at a constant value.

Advantageous Effects of Invention

A laser device according to the present invention provides an advantage in being capable of reducing further degradation of a degraded laser module while maintaining the laser output value after coupling of the laser beams within an acceptable range.

DESCRIPTION OF EMBODIMENT

A laser device, a laser machining apparatus, and a method for controlling an output of a laser device according to an embodiment of the present invention will be described in detail below with reference to the drawings. Note that this embodiment is not intended to limit the scope of this invention.

Embodiment

FIG. 1is a diagram illustrating a configuration of a laser device according to an embodiment. A laser device100A includes a first laser module M1, a second laser module M2, and a third laser module M3. The laser device100A also includes a first drive power supply41, a second drive power supply42, and a third drive power supply43as multiple drive power units. The laser device100A further includes partial reflection mirrors61to63, a first output detection unit51, a second output detection unit52, and a third output detection unit53. The laser device100A also includes an optical coupling unit15, a coupled output detection unit55, and a control device5A.

The first laser module M1, the first drive power supply41, and the first output detection unit51together constitute one laser unit that outputs and detects a laser beam. The second laser module M2, the second drive power supply42, and the second output detection unit52also together constitute one laser unit that outputs and detects a laser beam. The third laser module M3, the third drive power supply43, and the third output detection unit53also together constitute one laser unit that outputs and detects a laser beam. Note that the laser unit including the first output detection unit51may include the partial reflection mirror61as a component thereof; the laser unit including the second output detection unit52may include the partial reflection mirror62as a component thereof; and the laser unit including the third output detection unit53may include the partial reflection mirror63as a component thereof. The present embodiment is described in the context of the laser device100A including three laser modules, i.e., the first laser module M1, the second laser module M2, and the third laser module M3, but the laser device100A may include two, or four or more, laser modules.

The first laser module M1is a module that outputs a laser beam W1, and includes, in a housing, a total reflection mirror11, a partial reflection mirror21, and an excitation unit31. The second laser module M2is a module that outputs a laser beam W2, and includes, in a housing, a total reflection mirror12, a partial reflection mirror22, and an excitation unit32. The third laser module M3is a module that outputs a laser beam W3, and includes, in a housing, a total reflection mirror13, a partial reflection mirror23, and an excitation unit33.

The first laser module M1, the second laser module M2, and the third laser module M3have similar functions to each other. That is, the total reflection mirrors12and13each have a similar function to the function of the total reflection mirror11. The partial reflection mirrors22and23each have a similar function to the function of the partial reflection mirror21. The excitation units32and33each have a similar function to the function of the excitation unit31.

The following description will focus on a configuration of the first laser module M1. The first laser module M1may use any type of laser including a gas laser, a fiber laser, or a direct diode laser. The present embodiment will be described on the assumption that the first laser module M1is a laser module using a gas laser. The housing of the first laser module M1contains laser gas sealed therein, such as carbon dioxide (CO2), carbon monoxide (CO), helium (He), nitrogen (N2), or hydrogen (H2), serving as the laser medium of the gas laser. In the first laser module M1, electric discharge in the excitation unit31excites the laser gas, and light generated therefrom travels back and forth repeatedly between the total reflection mirror11and the partial reflection mirror21, thereby producing resonance. The partial reflection mirror21allows a part of incident light to pass therethrough. The light transmitted through the partial reflection mirror21is then output from the first laser module M1as the laser beam W1.

Note that, in the following description, the first laser module M1, the second laser module M2, or the third laser module M3may also be referred to as laser module Mx. In addition, the first laser module M1, the second laser module M2, and the third laser module M3may be referred to collectively as laser module group. Moreover, the first drive power supply41, the second drive power supply42, or the third drive power supply43may also be referred to as drive power supply40x. Furthermore, the first drive power supply41, the second drive power supply42, and the third drive power supply43may be referred to collectively as drive power supply group.

A part of the laser beam W1from the first laser module M1is reflected by the partial reflection mirror61, and is directed to the first output detection unit51. The rest thereof passes through the partial reflection mirror61, and is directed to the optical coupling unit15. The partial reflection mirror61allows almost all the laser beam to pass therethrough, thereby causing the part of the laser beam reflected by the partial reflection mirror61to have significantly low power. Accordingly, the present embodiment is described on the assumption that the laser beam from the first laser module M1and the laser beam directed to the optical coupling unit15have a same amount of power. The laser beam from the first laser module M1and the laser beam having passed through the partial reflection mirror61are thus hereinafter both referred to as laser beam W1. Similarly, the laser beam from the second laser module M2and the laser beam having passed through the partial reflection mirror62are both referred to as laser beam W2; and the laser beam from the third laser module M3and the laser beam having passed through the partial reflection mirror63are both referred to as laser beam W3. In the following description, any of the laser beams W1, W2, and W3may also be referred to as laser beam Wx. In addition, the laser beams W1, W2, and W3may be referred to collectively as laser beam group.

The first output detection unit51, the second output detection unit52, and the third output detection unit53are each a laser output detection unit, such as a sensor for detecting an output value of the laser beam Wx, which indicates the power of the laser beam Wx. The first output detection unit51detects the laser beam incident from the partial reflection mirror61, converts the detected laser beam into an output signal P1, which is an electrical signal (voltage), and transmits the output signal P1to the control device5A. The output signal P1corresponds to the output value of the laser beam W1output from the first laser module M1.

The second output detection unit52detects the laser beam incident from the partial reflection mirror62, converts the detected laser beam into an output signal P2, which is an electrical signal, and transmits the output signal P2to the control device5A. The output signal P2corresponds to the output value of the laser beam W2output from the second laser module M2.

The third output detection unit53detects the laser beam incident from the partial reflection mirror63, converts the detected laser beam into an output signal P3, which is an electrical signal, and transmits the output signal P3to the control device5A. The output signal P3corresponds to the output value of the laser beam W3output from the third laser module M3. In the following description, the first output detection unit51, the second output detection unit52, and the third output detection unit53may be referred to collectively as output detection unit group.

The laser beam W1having passed through the partial reflection mirror61, the laser beam W2having passed through the partial reflection mirror62, and the laser beam W3having passed through the partial reflection mirror63are directed to the optical coupling unit15.

The optical coupling unit15couples together the laser beams W1, W2, and W3from the laser module group. In the following description, the laser beams W1, W2, and W3after the coupling may also be referred to as coupled laser beam. The optical coupling unit15includes a partial reflection mirror65. A part of the coupled laser beam is reflected by the partial reflection mirror65, and is directed to the coupled output detection unit55. The rest thereof passes through the partial reflection mirror65, and is output out of the laser device100A. The partial reflection mirror65allows almost all the laser beam to pass therethrough, thereby causing the part of the laser beam reflected by the partial reflection mirror65to have significantly low power. Accordingly, the present embodiment is described on the assumption that the laser beam incident on the partial reflection mirror65and the laser beam going out of the partial reflection mirror65have a same amount of power. Thus, the laser beam incident on the partial reflection mirror65and the laser beam going out of the partial reflection mirror65are hereinafter both referred to as coupled laser beam W10.

The coupled output detection unit55is a sensor for detecting an output value of the coupled laser beam W10, which indicates the power of the coupled laser beam W10. The coupled output detection unit55detects the laser beam incident from the partial reflection mirror65, converts the detected laser beam into an output signal P10, which is an electrical signal, and transmits the output signal P10to the control device5A. The output signal P10corresponds to a total laser output, which is output after the coupling of the laser beams W1, W2, and W3by the optical coupling unit15, that is, an output value of the coupled laser beam W10. The output signals P1to P3are each a first output signal, and the output signal P10is a second output signal.

The control device5A is a device that controls the laser module group and the drive power supply group. The control device5A includes a computing unit1A, a control unit2A, and a memory unit3A.

The memory unit3A stores, on a per laser module Mx basis, correspondence relationship information, which represents correspondence relationship between the power to be supplied to the drive power supply group and the output value of the laser beam Wx. The memory unit3A stores the correspondence relationship information in an initial state of the laser device100A, and the correspondence relationship information for correcting the output values of the laser beam group. The information of the power to be supplied to the drive power supply group includes the current value of the drive current and the voltage value of the drive voltage of each of the laser modules Mx (hereinafter referred to as each laser module Mx).

The output values of the laser beams Wx included in the correspondence relationship information include an initial value, i.e., an output value in the initial state, a latest output value, and the like, of the laser device100A. The initial value of a laser beam Wx is the output value of that laser beam Wx that has been output at a time of setting of the initial state of the laser device100A. An example of the time of setting of the initial state is a time after elapse of a time period of possible occurrence of early failure of a laser module Mx and before elapse of a specific time period in a lifetime expected for that laser module Mx. The lifetime expected for a laser module Mx is a total expected energization time, i.e., the total time of the time expected to be energizable, of that laser module Mx. An example of the specific time period in the lifetime expected for a laser module Mx is 1/100 of the total energization time. The lifetime and the specific time period both correspond to a time when that laser module Mx is in operation, and exclude a time not in operation.

The memory unit3A also stores the output value of the coupled laser beam W10. Types of the output value of the coupled laser beam W10stored in the memory unit3A include an initial value of the output value, a latest output value, and the like. The initial value of the coupled laser beam W10corresponds to the initial values of the output values of the laser beams W1, W2, and W3. The initial values of the laser beams W1, W2, and W3and of the coupled laser beam W10are used as reference values for use in correction of the laser output value. The memory unit3A further stores an upper limit value of the output value of a laser beam Wx; an upper limit value of an output correction factor for correction of the output value of a laser beam Wx; and a measurement error range of the output value of a laser beam Wx. The output correction factor is a correction factor for the output of a laser beam Wx. The correspondence relationship information and the output value of the coupled laser beam W10constitute information representing the device status of the laser device100A. The correspondence relationship information for the initial state of the laser device100A and the initial value of the output value of the coupled laser beam W10serve as reference information of the device status of the laser device100A.

The computing unit1A sets the output correction factor for correction of the output value of the laser beam Wx. If the output value of the laser beam Wx needs to be increased by 10%, the computing unit1A sets the output correction factor to 10%. The computing unit1A of the present embodiment sets a lower output correction factor to a more degraded laser module Mx, and sets a higher output correction factor to a less degraded laser module Mx while maintaining the output value of the coupled laser beam W10within an acceptable range. In other words, the computing unit1A sets the output correction factors of the laser module group so as to set a lower output correction factor to a more degraded laser module Mx, and at the same time, to maintain the output value of the coupled laser beam W10within a specific range as a whole. The computing unit1A sets the output correction factors, for example, to maintain the output value of the coupled laser beam W10at a constant value. The term “constant value” as used herein also refers to a generally constant value. That is, it suffices that the constant value falls within a range allowing the value to be deemed as a particular value. The control unit2A calculates the values of the power to be supplied to the drive power supply group that reflect the output correction factors, using the correspondence relationship information in the memory unit3A and/or the like. The control unit2A sends the calculated values of the power to be supplied, to the drive power supply group.

A configuration of a laser machining apparatus including the laser device100A will now be described.FIG. 2is a diagram illustrating a first example configuration of a laser machining apparatus including the laser device according to the embodiment.FIG. 2omits illustration of the optical coupling unit15. A laser machining apparatus200A includes the laser device100A, a transmission fiber111, a machining apparatus drive unit110, which is a machining unit, and a machining apparatus control device120A.

The laser device100A is connected to the transmission fiber111that transmits the coupled laser beam W10, and transmits the coupled laser beam W10through the transmission fiber111to the machining apparatus drive unit110. In addition, the control unit2A of the laser device100A sends information representing the state of the laser device100A etc. to a machining apparatus control unit123. The information representing the state of the laser device100A is used in feedback control by the machining apparatus control device120A.

The machining apparatus drive unit110performs machining of a workpiece114, which is the item to be worked, using the coupled laser beam W10transmitted from the laser device100A. The machining apparatus drive unit110includes a machining head112and a worktable113.

The machining head112is connected through the transmission fiber111to the laser device100A, and emits the coupled laser beam W10transmitted through the transmission fiber111onto the workpiece114. The machining head112is movable along the vertical direction, i.e., Z-axis direction. The worktable113is a table for placing the workpiece114thereon. The worktable113is movable along X-axis and Y-axis directions in the horizontal plane.

The machining apparatus control device120A controls the machining apparatus drive unit110and the laser device100A. The machining apparatus control device120A includes a computing unit121, a memory unit122, the machining apparatus control unit123, and a user interface unit124. The machining apparatus control unit123is connected to the computing unit121, the memory unit122, the user interface unit124, the control unit2A, and the machining apparatus drive unit110. The user interface unit124receives information that is input by the user, and sends the information to the machining apparatus control unit123. In addition, the user interface unit124outputs various information to an external device according to a command from the machining apparatus control unit123.

The computing unit121calculates the position of the machining head112, the position of the worktable113, and the like, based on state information representing the state of the machining apparatus drive unit110. The memory unit122stores a control program for controlling the machining apparatus drive unit110and the laser device100A.

The machining apparatus control unit123receives the state information of the machining apparatus drive unit110from the machining apparatus drive unit110, and sends the state information to the computing unit121. The machining apparatus control unit123also receives various commands for controlling the machining apparatus drive unit110and the laser device100A, from the laser device100A. In addition, the machining apparatus control unit123sends a command for controlling the machining apparatus drive unit110to the machining apparatus drive unit110.

Moreover, the machining apparatus control unit123stores information generated by the machining apparatus control unit123, in the memory unit122. The machining apparatus control unit123also stores, in the memory unit122, information received from the machining apparatus drive unit110and from the laser device100A.

The machining apparatus control unit123calculates commands to send to the machining apparatus drive unit110and to the laser device100A using a result of computation of the computing unit121and using a control program in the memory unit122. The machining apparatus control unit123controls the machining apparatus drive unit110and the laser device100A by sending the calculated commands to the machining apparatus drive unit110and the laser device100A.

FIG. 3is a diagram illustrating a second example configuration of a laser machining apparatus including the laser device according to the embodiment.FIG. 3omits illustration of the optical coupling unit15. Of the elements illustrated inFIG. 3, elements that provide functionality identical to the functionality of the laser device100A illustrated inFIG. 2are indicated by the same reference characters, and duplicate description will be omitted. A laser machining apparatus200B includes a laser device100B, the transmission fiber111, the machining apparatus drive unit110, and a machining apparatus control device120B.

The laser device100B includes a control unit2B in place of the control unit2A. In the laser machining apparatus200B, a computing unit1B, which has both the functionality of the computing unit1A and the functionality of the computing unit121, is disposed in the machining apparatus control device120B. In addition, in the laser machining apparatus200B, a memory unit3B, which has both the functionality of the memory unit3A and the functionality of the memory unit122, is disposed in the machining apparatus control device120B. Note that at least one of the computing unit1B and the memory unit3B may be disposed in the laser device100B.

The machining apparatus control device120B includes the computing unit1B, the memory unit3B, the machining apparatus control unit123, and the user interface unit124. The machining apparatus control unit123is connected to the computing unit1B, the memory unit3B, the user interface unit124, the control unit2B, and the machining apparatus drive unit110.

The output signals P1, P2, P3, and P10detected in the laser device100B is transmitted by the control unit2B to the computing unit1B through the machining apparatus control unit123. This enables the computing unit1B to set the output correction factors in a processing similar to that of the computing unit1A. The machining apparatus control unit123sends the output correction factors calculated by the computing unit1B to the control unit2B. In addition, the control unit2B reads information in the memory unit3B through the machining apparatus control unit123.

The control unit2B controls the drive power supply group in a processing similar to the control unit2A. Specifically, the control unit2B calculates the values of the power to be supplied to the drive power supply group that reflect the output correction factors, using the correspondence relationship information in the memory unit3B and/or the like. The control unit2B sends the calculated values of the power to be supplied, to the drive power supply group.

FIG. 4is a flowchart illustrating a processing procedure of the laser device according to the embodiment. Due to similar processing performed by the laser device100A and by the laser device100B, the following description will focus on a processing procedure of the laser device100A. Upon connection of the first laser module M1, the second laser module M2, and the third laser module M3to the optical coupling unit15, the control device5A registers the initial states of the laser modules Mx and the initial state of the optical coupling unit15(step S10). Specifically, the control device5A registers the initial values of the laser output values of the laser modules Mx and the initial value of the laser output value of the optical coupling unit15. The initial values of the output values of the respective laser beams W1, W2, and W3are each a first initial value, and the initial value of the output value of the coupled laser beam W10is a second initial value.

An operation of registration of the initial state will now be described. At the time for registration of the initial state of the laser device100A, the control unit2A supplies power to the drive power supply group. In this operation, the control unit2A may supply different amounts of power on a per drive power supply40xbasis.

In the laser device100A, the first output detection unit51, the second output detection unit52, and the third output detection unit53respectively detect the laser beams W1, W2, and W3from the laser modules Mx, and the coupled output detection unit55detects the coupled laser beam W10from the optical coupling unit15. In this operation, the output values of the laser beams W1, W2, and W3and of the coupled laser beam W10are detected upon elapse of a specific time period after start-up of the laser modules Mx. That is, the output values of the laser beams W1, W2, and W3and of the coupled laser beam W10are detected after completion of a particular operation after start-up of the laser modules Mx. The output values of the laser beams W1, W2, and W3and of the coupled laser beam W10detected after completion of this particular operation are the initial values of the laser output values. Note that in a case in which part of the laser module group is replaced, the laser beam is detected for the replaced laser module(s) Mx to detect the initial value of the laser output value thereof.

The computing unit1A associates the detected initial values with the values of power to be supplied to the laser modules Mx on a per laser module Mx basis, and registers the resultant information in the correspondence relationship information in the memory unit3A. In addition, the computing unit1A stores the initial value of the coupled laser beam W10in the memory unit3A. The following description refers to the value of power, which is to be supplied to a laser module Mx upon detection of the initial value of the laser output value, as laser output condition A.

Assume here that the initial value of the output value of the laser beam Wx at a laser module Mx is V0(m) [kW], and that the initial value of the output value of the coupled laser beam W10at the optical coupling unit15is Va0[kW], where m ranges from 1 to N when there are N laser modules Mx, and N is a natural number.

In addition, the computing unit1A sets the measurement error range of the laser output values. An example of the measurement error range is X [%] or less. The computing unit1A stores the measurement error range that has been set, in the memory unit3A.

After registration of the initial state of the laser device100A, each laser module Mx outputs a laser beam, thereby causing the coupled laser beam W10to be output from the laser device100A. The control device5A then periodically checks the states of the laser modules Mx and the state of the optical coupling unit15at specific times such as once per day (step S20), and registers the states of the laser modules Mx and the state of the optical coupling unit15. Specifically, the control device5A stores the values of power to be supplied, the laser output values of the laser modules Mx, and the laser output value of the optical coupling unit15, in the memory unit3A.

An operation of checking the laser output values will next be described. At the time for checking the state of the laser device100A, the control unit2A supplies power to the drive power supplies40x. In this operation, the control unit2A supplies power equivalent to the laser output condition A to each of the drive power supplies40x.

In the laser device100A, the first output detection unit51, the second output detection unit52, and the third output detection unit53respectively detect the output values of the laser beams W1, W2, and W3from the laser modules Mx, and send these output values to the computing unit1A. In addition, the coupled output detection unit55detects the output value of the coupled laser beam W10from the optical coupling unit15, and sends the output value to the computing unit1A. In this operation, the output values of the laser beams W1, W2, and W3and of the coupled laser beam W10are detected upon elapse of a specific time period after start-up of the laser modules Mx. That is, the output values of the laser beams W1, W2, and W3and of the coupled laser beam W10are detected after completion of a particular operation after start-up of the laser modules Mx. Assume here that the output value of the laser beam Wx at a laser module Mx is V(m) [kW], and that the output value of the coupled laser beam W10at the optical coupling unit15is Va[kW]. The computing unit1A compares the output values calculated, with the output values stored in the memory unit3A, and calculates an output change ratio, which indicates the degree of degradation of the laser module Mx, based on the result of the comparison.

The computing unit1A herein calculates the output change ratio α(m) [%] of a laser module Mx by α(m)=1−V(m)/V0(m), and calculates the output change ratio αa[%] of the optical coupling unit15by αa=1−Va/Va0.

The computing unit1A calculates the output correction factor of each laser module Mx using the output change ratio α(m) of each laser module Mx and using the output change ratio αaof the optical coupling unit15(step S30). A processing procedure of calculation of the output correction factors will next be described.

FIG. 5is a flowchart illustrating a processing procedure of calculation of the output correction factors performed by the laser device according to the embodiment. Due to similar processing performed by the laser device100A and by the laser device100B, the following description will focus on a processing procedure of calculation of the output correction factors performed by the laser device100A.

The computing unit1A determines whether the output change ratio αaof the coupled laser beam W10falls within a measurement error range (step S110). In this operation, the computing unit1A determines whether a condition αa≤±X/m [%] is satisfied.

In a case in which the output change ratio αaof the coupled laser beam W10falls within the measurement error range (Yes at step S110), the computing unit1A equally corrects the laser output values of the laser modules Mx (step S120). Specifically, the computing unit1A sets a same output correction factor η(m)=ηa=Va0/Vato the laser modules Mx. For example, if the output change ratio αaof the coupled laser beam W10indicates a 1% decrease, the computing unit1A sets ηa=100/99 as the output correction factors η(m).

In a case in which the output change ratio αaof the coupled laser beam W10exceeds the measurement error range (No at step S110), the computing unit1A calculates variation of the output change ratios α(m) across the laser modules Mx (step S130). Specifically, the computing unit1A calculates an average value αave[%], a maximum value αmax[%], and a minimum value αmin[%] of the output change ratios α(m) [%] of the laser module group. The computing unit1A then calculates a variation β [%] of the output change ratios α(m) across the laser modules Mx. An example of β is β=(αmax−αmin)/αave.

The computing unit1A determines whether the variation β of the output change ratios α(m) falls within a measurement error range (step S140). In this operation, the computing unit1A determines whether a condition β≤±X [%] is satisfied. In a case in which the variation β of the output change ratios α(m) falls within the measurement error range (Yes at step S140), the computing unit1A equally corrects the laser output values of the laser modules Mx (step S120).

In a case in which the variation β of the output change ratios α(m) exceeds the measurement error range (No at step S140), the computing unit1A classifies the laser modules Mx based on the output change ratios α(m) of the laser modules Mx (step S150).

An example of classification of the laser modules Mx will now be described. For example, the computing unit1A selects a first laser module Mx from the laser module group, picks out a laser module Mx having an output change ratio different from the output change ratio of the first laser module Mx by X [%] or less, and registers the picked up laser module Mx as belonging to a first group together with the first laser module Mx. The computing unit1A excludes the laser module(s) having been registered as belonging to that group from the laser module group, and then selects a second laser module Mx. The computing unit1A then picks out a laser module Mx having an output change ratio different from the output change ratio of the second laser module Mx by X [%] or less, and registers the picked up laser module Mx as belonging to a second group together with the second laser module Mx. The computing unit1A repeats this operation until each of all the laser modules Mx of the laser module group are registered as belonging to a certain group. This operation assumes that each group includes at least one laser module Mx registered as belonging thereto.

The computing unit1A sets a lower output correction value to a laser module Mx having a higher output change ratio α (step S160). Specifically, the computing unit1A assigns numbers to the laser modules Mx in descending order of the output change ratios α(m) thereof. In addition, the computing unit1A calculates, for each laser module Mx, the output correction value for restoration of the laser output value to the initial value.

The computing unit1A then sets, to the laser module Mx having the highest output change ratio α, the output correction value for the laser module Mx having the lowest output change ratio α. In addition, the computing unit1A sets, to the laser module Mx having the lowest output change ratio α, the output correction value for the laser module Mx having the highest output change ratio α. Moreover, the computing unit1A sets, to the laser module Mx having the second highest output change ratio α, the output correction value for the laser module Mx having the second lowest output change ratio α. Furthermore, the computing unit1A sets, to the laser module Mx having the second lowest output change ratio α, the output correction value for the laser module Mx having the second highest output change ratio α.

The computing unit1A repeats such swap operation of output correction values until the output correction values are set to all the laser modules Mx of the laser module group. Then, the computing unit1A equalizes the output correction factors η(m) of the laser modules Mx in each group (step S170). That is, the computing unit1A sets a same output correction factor η(m) to the laser modules Mx registered as belonging to a same group.

In addition, the computing unit1A calculates the output value of the coupled laser beam W10obtained by correcting the laser outputs using the output correction values set to the laser modules Mx. Specifically, the computing unit1A sums up the laser output values obtained by correcting the laser outputs using the output correction values set to the laser modules Mx thus to calculate the output value of the coupled laser beam W10. The computing unit1A determines whether the difference between the calculated output value of the coupled laser beam W10and the initial value of the coupled laser beam W10stored in the memory unit3A falls within an acceptable range (step S180). An example of the acceptable range is the measurement error range.

In a case of being out of the acceptable range (No at step S180), the computing unit1A modifies the output correction factors η(m) on a per group basis (step S190). This allows the output correction factors η(m) in each group to be equivalent to each other. The computing unit1A repeats the operations of steps S180and S190until the difference between the calculated output value of the coupled laser beam W10and the initial value of the coupled laser beam W10stored in the memory unit3A falls within the acceptable range. When the difference falls within the acceptable range (Yes at step S180), the computing unit1A fixes the output correction factors η(m), and terminates the process of setting of the output correction factors η(m). The control unit2A calculates the values of power to be supplied corresponding to the output correction factors η(m), and sends the calculated values of power to be supplied, to the drive power supply group.

Note that it is assumed here that the computing unit1A calculates the output correction factors η(m) and sends the values of the power corresponding to the output correction factors η(m) to the drive power supply group immediately after checking the states of the laser modules Mx and the state of the optical coupling unit15. In addition, in performing the operations of steps S160, S170, and S190, the computing unit1A sets the output correction factors η(m) so as not to exceed the upper limit value of the output correction factors η(m) stored in the memory unit3A. Moreover, the computing unit1A may skip the operations of steps S150and S170. Furthermore, in performing the operation of step S190, the computing unit1A may modify the output correction values not on a per group basis, but on a per laser module Mx basis.

In addition, in performing the operation of step S160, it suffices for the computing unit1A to be capable of swapping the output correction values using at least two of the laser modules Mx. In this case, the computing unit1A gives priority to a more degraded laser module Mx in swapping the output correction values.

A specific example of what output correction factors η(m) are to be set depending on the state of the laser device100A will next be described.FIG. 6is a diagram illustrating the laser output values in the initial state of the laser device according to the embodiment. Note that the following description refers to the first laser module M1as laser module (1), the second laser module M2as laser module (2), and the third laser module M3as laser module (3).FIGS. 6 to 10each indicate the first laser module M1as module (1), the second laser module M2as module (2), and the third laser module M3as module (3). In the graphs illustrated inFIGS. 6 to 10, the vertical axis represents the laser output value (kW), i.e., the output value of the laser beam.

In the initial state, the laser device100A is in a state in which the laser output thereof has not decreased due to degradation. The present embodiment assumes that, in the initial state, the laser module (1) has a laser output of 1.1 kW, the laser module (2) has a laser output of 1.0 kW, and the laser module (3) has a laser output of 0.9 kW. The sum of the laser output values in this case is 3.0 kW. The sum of the laser outputs is the output value of the coupled laser beam W10. Continued operation of the laser device100A after registration of the initial state of the laser device100A may cause degradation, thereby leading to one of the first to fourth states described below.

FIG. 7is a diagram illustrating the laser output values in the first state of the laser device according to the embodiment. The first state of the laser device100A is a state in which the output change ratio α(m) of each laser module Mx falls within the measurement error range.

The following description assumes that the laser output values of the laser modules (1) and (3) have not decreased, the laser output value of the laser module (2) has decreased by 2%, and thus the sum of the laser output values has thus decreased by 0.67%.

In the first state, the computing unit1A sets a same output correction factor η(m) to each laser module Mx. In this case, the computing unit1A sets, to each laser module Mx, an output correction factor η(m) that maintains a difference between the sum of the laser output values and the sum in the initial state within an acceptable range.

FIG. 7illustrates a case in which the computing unit1A has set an output correction factor η of +0.67% to each of the laser modules (1) to (3). This brings the laser output values after the correction of the outputs of the laser modules (1) to (3) respectively to 1.107 (kW), 0.987 (kW), and 0.906 (kW), and the sum after the correction of the outputs to 3.000 (kW).

FIG. 8is a diagram illustrating the laser output values in the second state of the laser device according to the embodiment. The second state of the laser device100A is a state in which the laser output values of the laser modules Mx have equally decreased. That is, in the second state, the variation β in the decreasing ratios of the laser output values falls within a specific range.

The following description assumes that the laser output value of the laser module (1) has decreased by 10.0%, the laser output value of the laser module (2) has decreased by 10.0%, the laser output value of the laser module (3) has decreased by 8.9%, and the sum of the laser output values has thus decreased by 9.7%.

In the second state, the computing unit1A sets a same output correction factor η(m) to each laser module Mx. In this case, the computing unit1A sets, to each laser module Mx, an output correction factor η(m) that maintains the difference between the sum of the laser output values and the sum in the initial state within an acceptable range.

FIG. 8illustrates a case in which the computing unit1A has set an output correction factor η of +10.7% to each of the laser modules (1) to (3). This brings the laser output values after the correction of the outputs of the respective laser modules (1) to (3) to 1.096 (kW), 0.996 (kW), and 0.908 (kW), and the sum after the correction of the outputs to 3.000 (kW).

FIG. 9is a diagram illustrating the laser output values in the third state of the laser device according to the embodiment. The third state of the laser device100A is a state in which a group including a larger number of the laser modules Mx registered each having a laser output value slightly decreased, and a group including a smaller number of the laser modules Mx registered each having a laser output value significantly decreased are present. Assume that the laser modules (1) and (3) each having a laser output value slightly decreased are registered as belonging to the first group, and the laser module (2) having a laser output value significantly decreased is registered as belonging to the second group.

The following description assumes that the laser output value of the laser module (1) has decreased by 4.5%, the laser output value of the laser module (2) has decreased by 20.0%, the laser output value of the laser module (3) has decreased by 5.6%, and the sum of the laser output values has thus decreased by 10.0%.

In the third state, the computing unit1A assigns numbers to the laser modules (1) to (3) in descending order of the output change ratios α(m). In this example, the output change ratios α(m) decrease in the order of the laser module (2), the laser module (3), and the laser module (1).

In addition, the computing unit1A calculates an output correction value for restoration of the laser output value to the initial value, for each of the laser modules (1) to (3). Restoration of the laser output value of the laser module (1) to the laser output value in the initial state requires an output correction factor η of +4.8%. Restoration of the laser output value of the laser module (2) to the laser output value in the initial state requires an output correction factor η of +25.0%. Restoration of the laser output value of the laser module (3) to the laser output value in the initial state requires an output correction factor η of +5.9%.

The computing unit1A sets, to the laser module (2) having experienced the highest output change ratio α, the output correction factor η of the laser module (1) having experienced the lowest output change ratio α. That is, the computing unit1A sets the output correction factor η of +4.8% to the laser module (2).

In addition, the computing unit1A sets, to the laser module (1) having experienced the lowest output change ratio α, the output correction factor η of the laser module (2) having experienced the highest output change ratio α. That is, the computing unit1A tentatively sets an output correction factor η of +25.0% to the laser module (1).

Furthermore, because the laser modules (1) and (3) belong to a same group, the computing unit1A modifies the output correction factors η of the laser modules (1) and (3) to bring the output correction factors η of the laser modules (1) and (3) to a same value, and the difference between the sum after the correction of the outputs and the sum in the initial state to fall within an acceptable range.

FIG. 9illustrates a case in which the computing unit1A has set a modified output correction factor η of 15.5% to each of the laser modules (1) and (3), and sets an output correction factor η of +4.8% to the laser module (2). This brings the laser output values after the correction of the outputs of the laser modules (1) to (3) respectively to 1.213 (kW), 0.838 (kW), and 0.982 (kW), and the sum after the correction of the outputs to 3.033 (kW).

Because the laser modules (1) and (3) each have a low output change ratio α, setting of a high output correction factor η thereto can still prevent accelerated degradation. Moreover, although the laser module (2) has a high output change ratio α, setting of a low output correction factor η can prevent accelerated degradation.

FIG. 10is a diagram illustrating the laser output values in the fourth state of the laser device according to the embodiment. The fourth state of the laser device100A is a state in which a group including a smaller number of the laser modules Mx registered each having a laser output value slightly decreased, and a group including a larger number of the laser modules Mx registered each having a laser output value significantly decreased are present. Assume that the laser modules (1) and (3) each having a laser output value significantly decreased are registered as belonging to the first group, and the laser module (2) having a laser output value slightly decreased is registered as belonging to the second group.

The following description assumes that the laser output value of the laser module (1) has decreased by 13.6%, the laser output value of the laser module (2) has decreased by 2.0%, the laser output value of the laser module (3) has decreased by 13.3%, and the sum of the laser output values has thus decreased by 9.7%.

In the fourth state, the computing unit1A assigns numbers to the laser modules (1) to (3) in descending order of the output change ratios α(m). In this example, the output change ratios α(m) decrease in the order of the laser module (1), the laser module (3), and the laser module (2).

In addition, the computing unit1A calculates an output correction value for restoration of the laser output value to the laser output value in the initial state, for each of the laser modules (1) to (3). Restoration of the laser output value of the laser module (1) to the laser output value in the initial state requires an output correction factor η of +15.8%. Restoration of the laser output value of the laser module (2) to the laser output value in the initial state requires an output correction factor η of +2.0%. Restoration of the laser output value of the laser module (3) to the laser output value in the initial state requires an output correction factor η of +15.4%.

The computing unit1A sets, to the laser module (2) having experienced the lowest output change ratio α, the output correction factor η of the laser module (1) having experienced the highest output change ratio α. That is, the computing unit1A sets the output correction factor η of +15.8% to the laser module (2).

In addition, the computing unit1A sets, to the laser module (1) having experienced the highest output change ratio α, the output correction factor η of the laser module (2) having experienced the lowest output change ratio α. That is, the computing unit1A tentatively sets an output correction factor η of +2.0% to the laser module (1).

Furthermore, since the laser modules (1) and (3) belong to a same group, the computing unit1A modifies the output correction factors η of the laser modules (1) and (3) to bring the output correction factors η of the laser modules (1) and (3) to a same value, and the difference between the sum after the correction of the outputs and the sum in the initial state to fall within an acceptable range.

FIG. 10illustrates a case in which the computing unit1A has set a modified output correction factor η of 8.7% to each of the laser modules (1) and (3), and sets an output correction factor η of +15.8% to the laser module (2). This brings the laser output values after the correction of the outputs of the respective laser modules (1) to (3) respectively to 1.033 (kW), 1.133 (kW), and 0.848 (kW), and the sum after the correction of the outputs to 3.014 (kW).

Because the laser module (2) has a low output change ratio α, setting of a high output correction factor η can still prevent accelerated degradation. Moreover, although the laser modules (1) and (3) each have a high output change ratio α, setting of a low output correction factor η can prevent accelerated degradation.

As described above, in the present embodiment, the output correction factors η of the laser modules Mx are modified to reduce the burden on a largely-degraded laser module Mx of the laser modules Mx caused by correction of the outputs of the laser beams. In addition, the output correction factors η are modified to maintain the output value of the coupled laser beam W10within an acceptable range.

A hardware configuration of the control devices5A and5B will now be described. The control devices5A and5B can each be implemented in control circuitry, i.e., a processor and a memory. Note that the processor and the memory may be replaced with processing circuitry. The computing units1A and1B may also be implemented in control circuitry. The functionality of the control devices5A and5B and the computing units1A and1B may be partially implemented in a dedicated hardware element, and partially implemented in software or firmware.

As described above, in the present embodiment, the output value of the coupled laser beam W10is maintained within an acceptable range, and a lower output correction factor η is set to a laser module Mx having a higher output change ratio α, based on the laser output values of the laser modules Mx, on the output change ratios α(m) of the laser modules Mx, and on the initial value of the output value of the coupled laser beam W10. Because the computing unit1A is capable of modifying the output correction factors η(m) of the laser modules Mx depending on degradation situations of the laser modules Mx, the load on a laser module Mx having a short life expectancy can be reduced depending on a difference in life expectancy among the laser modules Mx. This can prevent accelerated degradation of the laser modules Mx while maintaining the laser output value of the optical coupling unit15within an acceptable range.

In addition, capability of preventing accelerated degradation of the laser modules Mx can prevent a sudden failure of the laser device100A, thereby ensuring a time for preparing for replacement of the laser module Mx. That is, replacement can be postponed from the start of degradation to the occurrence of failure of the laser module Mx.

Moreover, capability of comparing the states of the laser modules Mx with the initial states of the laser modules Mx allows degradation condition of each laser module Mx to be accurately identified. In other words, degradation condition can be accurately identified on a per laser module Mx basis even after part of the laser modules Mx in the laser module group is replaced.

Furthermore, in the present embodiment, the output values of the laser beams W1, W2, and W3and of the coupled laser beam W10are detected upon elapse of a specific time period after start-up of the laser modules Mx, and the output correction factors η(m) are calculated immediately after the detection to correct the values of the power for the drive power supply group. This enables the laser output values to be detected while maintaining, at a constant level, conditions related to laser oscillation such as a water temperature condition of each laser module Mx. This enables highly-reliable output correction control to be provided to the drive power supply group with a reduced variation in the states of the laser modules Mx.

The configurations described in the foregoing embodiment are merely examples of the aspects of the present invention. These configurations may be combined with another known technology, and moreover, a part of such configurations may be omitted and/or modified without departing from the spirit of the present invention.

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