Laser head, laser machining device equipped with the same, and method for protecting laser head

Abstract

To provide a laser head which enables sure suppression of an own temperature increase with a simple structure.SOLUTION: A laser head 50 comprises: a housing 51; a shield unit 40; and a state detection circuit 30. The state detection circuit 30 includes a temperature detector 31, an insertion detection switch 32, and an arithmetic unit 34. The shield unit 40 is detachably attached to the housing 51. The temperature detector 31 is attached to a holder 42. The insertion detection switch 32 for detecting the mounted state of the shield unit 40 to the housing 51 is attached to the housing 51. The arithmetic unit 34 calculates the temperature of the laser head 50 on the basis of an output signal from the temperature detector 31. The temperature detector 31 and the insertion detection switch 32 are connected in series.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a laser head, a laser processing apparatus including the same, and a method for protecting the laser head. [Background technology]

[0002] Conventionally, a laser processing device is well known in which a laser beam emitted from a laser oscillator is guided through an optical fiber to enter a laser head, and the laser beam is emitted from the laser head toward a workpiece. By using an optical fiber, it is possible to perform laser processing on a workpiece placed at a location away from the laser oscillator.

[0003] During laser processing, the laser head is located close to the workpiece, so that spatters, fumes, and other debris that melts the workpiece and is generated by the laser light may enter the inside of the laser head. Inside the laser head, multiple optical components are arranged in a predetermined arrangement relationship. If the debris adheres to these optical components, the laser light is reflected or scattered. For this reason, the laser light may not be irradiated with the desired output or to the desired position on the workpiece. To prevent this, one or more protective glasses are usually provided inside the laser head near the light emission port.

[0004] However, because debris attached to the protective glass absorbs the laser light, continuous laser processing causes the temperature of the protective glass to rise, which in turn causes the temperature of the entire laser head to rise. In extreme cases, there is a risk of the laser head burning out.

[0005] Various techniques have been proposed to solve such problems. For example, Patent Document 1 discloses a configuration in which two types of air nozzles with different spray directions are provided between the protective glass and the light exit port to blow air onto the protective glass to prevent adhesion of scattered particles.

[0006] Patent Document 2 discloses a configuration in which a work support member is provided near the opening of the work table to ensure a working distance from the tip of the laser head to the work so that scattered objects do not enter the inside of the laser head. Also, a protective cover with an inert gas outlet is provided on the inner periphery of the opening.

[0007] Patent Document 3 discloses a laser processing apparatus that discloses a temperature detector that detects the temperature of the focusing optics, a means for determining the amount of defocus from a map of temperature versus defocus amount based on the temperature detected by the temperature detector, and an offset for the determined defocus amount applied to a stage on which a workpiece is placed.

[0008] Patent Document 4 discloses a laser processing device that reduces the amount of scattered material by changing the wavelength of laser light depending on the material of the workpiece and irradiating the workpiece with the laser light. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Patent No. 5194367 [Patent Document 2] Patent No. 6091260 [Patent Document 3] Japanese Patent Application Publication No. 11-058053 [Patent Document 4] Patent No. 6631202 Summary of the Invention [Problem to be solved by the invention]

[0010] According to the conventional configurations disclosed in Patent Documents 1 to 4, the adhesion of flying debris and the temperature rise of the laser head can be suppressed by adjusting the method of blowing air onto the protective glass, the distance between the laser head and the workpiece, and the wavelength of the irradiated laser light, etc.

[0011] However, in the configuration disclosed in Patent Document 1, the flow rate of air that can be blown from the air nozzle is determined by the nozzle diameter and the diameter of the pipe to which the air nozzle is connected. Therefore, there is a risk that the flow rate of air blown onto the protective glass cannot be increased. On the other hand, if the air flow rate is too large, there is a risk that the processing quality of the workpiece will deteriorate.

[0012] In the configurations disclosed in Patent Documents 2 and 3, when the distance between the laser head and the workpiece is increased, the spot diameter of the laser light irradiated on the workpiece also increases. In this case, the penetration depth of the workpiece becomes smaller than the desired value, and there is a risk that machining that requires a deep penetration depth cannot be performed.

[0013] In addition, the wavelength dependency of light absorption rate changes depending on the material of the workpiece. For example, silver has an absorption rate of 90% or more in the wavelength range from 450nm to 1100nm. On the other hand, the absorption rate of gold drops sharply when the wavelength becomes shorter than 600nm, and the absorption rate at 450nm is about 40%.

[0014] In the configuration disclosed in Patent Document 4, the wavelength of the laser light is changed depending on the material of the workpiece. However, since the wavelength of the laser light is basically determined by the type of laser light source, it is not easy to make a large wavelength change or to widen the wavelength change range.

[0015] The present disclosure has been made in consideration of these points, and its purpose is to provide a laser head that can reliably suppress temperature rise in the laser head with a simple configuration, a laser processing apparatus equipped with the same, and a method for protecting the laser head. [Means for solving the problem]

[0016] In order to achieve the above-mentioned object, the laser head of the present disclosure is a laser head that irradiates the received laser light toward a workpiece, comprising at least a housing having a plurality of optical components therein and a shield unit removably attached to the housing, wherein the laser head further comprises a state detection circuit that detects a temperature state of the laser head and an attachment state of the shield unit to the housing, the shield unit has a protective glass and a holder that holds the protective glass, the holder is attached with a temperature detector that detects the temperature of the laser head, the housing is attached with an insertion detection switch that detects the attachment state of the shield unit to the housing, the temperature detector is attached near the protective glass, the state detection circuit has at least the temperature detector, the insertion detection switch, and a calculation unit, the calculation unit calculates the temperature of the laser head based on an output signal of the temperature detector, and the temperature detector and the insertion detection switch are connected in series.

[0017] The laser processing apparatus according to the present disclosure is characterized by including at least a laser oscillator that generates the laser light, the laser head, and a controller that controls at least the operation of the laser oscillator.

[0018] The method for protecting a laser head according to the present disclosure includes at least a first step of determining whether the status detection circuit is in an open state or a closed state before irradiating the laser light to the workpiece, a second step of starting irradiation of the laser light to the workpiece, a third step of measuring the temperature of the laser head using the temperature detector, a fourth step of deriving an amount of temperature change of the laser head over a predetermined period based on an output signal of the temperature detector, a fifth step of determining whether the amount of temperature change has exceeded a second threshold value, and a sixth step of determining whether the temperature of the laser head has exceeded a first threshold value, wherein in the first step, if the status detection circuit is in the closed state, processing from the second step onwards is continued, if the status detection circuit is in the open state, irradiation of the laser light to the workpiece is stopped, if either the judgment result of the fifth step or the judgment result of the sixth step is positive, irradiation of the laser light to the workpiece is stopped, and if both the judgment result of the fifth step and the judgment result of the sixth step are negative, irradiation of the laser light to the workpiece is continued. Effect of the Invention

[0019] According to the present disclosure, the temperature rise of the laser head can be reliably suppressed with a simple configuration. [Brief description of the drawings]

[0020] [Figure 1] 1 is a schematic configuration diagram of a laser processing device according to a first embodiment. [Diagram 2] FIG. 2 is a schematic diagram of a laser head. [Diagram 3] FIG. 2 is a schematic diagram of a shield unit. [Figure 4] FIG. 2 is a schematic diagram of a state detection circuit. [Diagram 5] FIG. 4 is a diagram showing the time response of an output signal of a temperature detector. [Figure 6] FIG. 4 is a diagram illustrating the amount of temperature change in a laser head over a certain period of time. [Figure 7]11 is a diagram showing the difference in time change in temperature of the laser head depending on whether or not the protective glass is dirty. [Figure 8] 5 is a flowchart showing a procedure for protecting the laser head according to the first embodiment. [Figure 9] 10 is a flowchart showing a procedure for protecting a laser head according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that the following description of the preferred embodiments is merely illustrative in nature and is not intended to limit the present disclosure, its application, or its uses.

[0022] (Embodiment 1) [Laser processing equipment configuration] Fig. 1 is a schematic configuration of a laser processing apparatus according to embodiment 1. As shown in Fig. 1, the laser processing apparatus 100 includes a laser head 50, a manipulator 60, a controller 70, a laser oscillator 80, and an optical fiber 90.

[0023] The laser head 50 irradiates the laser light LB transmitted through the optical fiber 90 toward the workpiece W. The configuration of the laser head 50 will be described in detail later.

[0024] The manipulator 60 is a multi-joint robot, and has the laser head 50 attached to its tip, and moves the laser head 50. The manipulator 60 and the controller 70 are connected by a first cable 71. A servo motor (not shown) is attached to each joint shaft (not shown), and a command signal is input from the controller 70 via the first cable 71 to control the driving of the servo motor. An output signal from a rotation amount measuring device such as an encoder (not shown) attached to each servo motor is input to the controller 70 via the first cable 71. The moving speed of the laser head 50 is controlled based on the output signal.

[0025] The controller 70 has one or more central processing units (CPUs) or microcontroller units (MCUs) (neither of which is shown in the figures). The controller 70 also has, as a storage unit, a semiconductor memory such as a read only memory (ROM), a random access memory (RAM), or a solid state drive (SSD), or a hard disk drive (HDD), or both (neither of which is shown in the figures).

[0026] The controller 70 controls the operation of the laser oscillator 80 including laser oscillation, the operation of the manipulator 60, and the operation of the laser head 50. Specifically, the controller 70 operates a power supply (not shown) in the laser oscillator 80, and controls the power of the laser light LB, the on / off timing, and the like. The controller 70 also controls the operation of each servo motor of the manipulator 60 described above. Furthermore, in the case where the laser head 50 is provided with movable parts, the controller 70 controls the operation of the movable parts.

[0027] The controller 70 is connected to a number of components provided in the laser head 50 via signal lines 72a and 72b. For ease of explanation, the signal lines 72a and 72b are shown separated from each other in Fig. 1, but in reality, these signal lines are integrated into a single cable. The signal lines 72a and 72b will be described later.

[0028] It is sufficient that the controller 70 controls at least the operation of the laser oscillator 80. For example, a controller that controls the operation of the manipulator 60 and a controller that controls the operation of the laser head 50 may be provided separately from the controller 70.

[0029] The laser oscillator 80 generates laser light LB by laser oscillation and outputs the laser light LB to an optical fiber 90. The optical fiber 90 transmits the laser light LB output from the laser oscillator 80 to the laser head 50.

[0030] 1 is used for cutting, welding, drilling, and the like of a workpiece W. In the laser processing apparatus 100, a controller 70 operates a laser oscillator 80 to generate laser light LB. Furthermore, the controller 70 operates a manipulator 60, or operates both the laser head 50 and the manipulator 60, to irradiate the workpiece W with the laser light LB and perform laser processing.

[0031] [Laser head configuration] Fig. 2 is a schematic diagram of the laser head, and Fig. 3 is a schematic diagram of the shield unit.

[0032] 2, the laser head 50 has a housing 51 and a plurality of components arranged in a predetermined arrangement relationship inside the housing 51. A substrate box 20 is attached to the outer peripheral surface of the housing 51. Note that, although FIG. 2 shows the collimation lens 10, the focus lens 11, and two pairs of shield units 40, 40 as components arranged inside the housing 51, components other than these may be provided inside the housing 51.

[0033] The board box 20 has an internal repeater (not shown) for an electrical signal that is input to the laser head 50 or a signal processing unit for the electrical signal that is input to the laser head 50. As the signal processing unit, a calculation unit 34 (see FIG. 4), which will be described later, is disposed in the board box 20. Note that a signal processing unit other than the calculation unit 34 or an electrical circuit may be provided in the board box 20.

[0034] The housing 51 has a light inlet 51a and a light outlet 51b. An optical fiber 90 is connected to the light inlet 51a. The laser light LB generated by the laser oscillator 80 passes through the optical fiber 90 and enters the inside of the housing 51 from the light inlet 51a. The laser light LB further passes through the multiple components described above and is irradiated toward the workpiece W from the light outlet 51b.

[0035] The collimation lens 10 collimates the laser light LB, and the focus lens 11 receives the laser light LB collimated by the collimation lens 10 and collects the laser light LB so as to form a focal point on the surface of the workpiece W or in its vicinity.

[0036] Further, two pairs of shield units 40, 40 are arranged near the light exit port 51b inside the housing 51. The two pairs of shield units 40, 40 are arranged at an interval in the traveling direction of the laser light LB inside the housing 51. Note that, although two pairs of shield units 40, 40 are arranged inside the housing 51 in the example shown in Fig. 2, one or more shield units 40 may be further arranged.

[0037] 3, the shield unit 40 has a protective glass 41 and a holder 42 that holds the protective glass 41. The shield unit 40 is detachably attached to a housing 51. When the shield unit 40 is properly inserted into the housing 51, the holder 42 comes into contact with an insertion detection switch 32 attached to the housing 51 as shown in FIGS. 2 and 3. The function of the insertion detection switch 32 will be described later.

[0038] The protective glass 41 is an optical member made of a material transparent to the laser light LB. The protective glass 41 transmits the laser light LB, while preventing flying objects such as spatters and fumes flying from the workpiece W during laser processing from entering the inside of the housing 51. In the laser head 50 shown in this embodiment, two sets of shield units 40 are provided, thereby reliably preventing flying objects from entering the inside of the housing 51.

[0039] By providing the shield unit 40 having the protective glass 41 near the light exit port 51b, it is possible to prevent scattered objects from adhering to the collimation lens 10 and the focus lens 11. This allows the laser light LB to be irradiated to a desired position on the workpiece W with a predetermined output.

[0040] On the other hand, the scattered debris adheres to the protective glass 41. If the amount of the scattered debris increases, the progress of the laser light LB is impeded. In addition, the scattered debris absorbs the laser light LB and generates heat, causing the temperature of the protective glass 41 to rise. As described above, if the temperature of the protective glass 41 rises too much, the shield unit 40 and ultimately the laser head 50 may be burned out.

[0041] Therefore, in this embodiment, the state detection circuit 30 is provided in the laser head 50 to reliably detect the temperature of the laser head 50. Also, the operation of the laser oscillator 80 is controlled based on the detected temperature. This will be described in further detail below.

[0042] [Status detection circuit configuration] Fig. 4 is a schematic diagram of the state detection circuit. For ease of explanation, in Fig. 4, the shape of the holder 42 is simplified and the protective glass 41 is not shown. Also, the housing 51 is not shown.

[0043] As shown in FIG. 4, the state detection circuit 30 is made up of a temperature detector 31, an insertion detection switch 32, and a calculation unit .

[0044] The temperature detector 31 is attached to a holder 42 of the shield unit 40. In this embodiment, the temperature detector 31 is a thermocouple. However, the present invention is not limited to this, and the temperature detector 31 may be another type of element. In this embodiment, the temperature detector 31 is attached to the shield unit 40 disposed on the side closer to the light exit port 51b.

[0045] By attaching the temperature detector 31 to a holder 42 disposed near the protective glass 41, the temperature of the protective glass 41 can be detected without impeding the progress of the laser light LB. In addition, the temperature of the protective glass 41 represents the temperature of the shield unit 40 and, ultimately, the temperature of the laser head 50.

[0046] The insertion detection switch 32 is a typical push button switch. When the holder 42 is inserted to a set position in the housing 51, the holder 42 presses the tip of the insertion detection switch 32, and the state of the insertion detection switch 32 changes from an open state (hereinafter also referred to as an open state) to a closed state (hereinafter also referred to as a closed state).

[0047] The calculation unit 34 is composed of one or more CPUs. The calculation unit 34 calculates the temperature of the shield unit 40 based on the output signal of the temperature detector 31, specifically, the output voltage, and a table describing the relationship between the output voltage value of the temperature detector 31 and the temperature that has been obtained in advance.

[0048] The output signal of the insertion detection switch 32 is also input to the calculation unit 34. Based on the output signal of the insertion detection switch 32, the calculation unit 34 determines whether the insertion detection switch 32 is in an open state or a closed state.

[0049] As shown in Fig. 4, the holder 42 is provided with two electrical contacts 33a, 33b. One end of the temperature detector 31 is connected to the electrical contact 33a, and the other end is connected to the electrical contact 33b. Of the two signal lines connected to the insertion detection switch 32, one is connected to the electrical contact 33b. In other words, the temperature detector 31 and the insertion detection switch 32 are connected in series via the electrical contact 33b. The other signal line connected to the insertion detection switch 32 is signal line 72b, which is connected to the controller 70. Further, another signal line is connected to the electrical contact 33a, and this signal line is connected to the calculation unit 34. In the example shown in Fig. 4, the temperature detector 31, the insertion detection switch 32, and the calculation unit 34 are connected in series. Furthermore, the calculation unit 34 is connected to the controller 70 via a signal line 72a.

[0050] In other words, the state detection circuit 30 and the controller 70 are connected in series to form a closed circuit.

[0051] The controller 70 receives the output result of the calculation unit 34 and controls the operation of the laser oscillator 80 to protect the laser head 50. Specifically, when the temperature of the laser head 50, represented by the temperature of the protective glass 41, is outside a predetermined range, the controller 70 sends a stop signal to a power source (not shown) to stop the laser oscillation in the laser oscillator 80. Also, when the insertion detection switch 32 is in the closed state, the controller 70 stops the laser oscillation in the laser oscillator 80. This will be further described below.

[0052] [Laser head protection procedure] FIG. 5 is a diagram showing the time response of the output signal of the temperature detector. FIG. 6 is a diagram explaining the amount of temperature change of the laser head over a certain period of time. FIG. 7 is a diagram showing the difference in time change in the temperature of the laser head depending on whether or not the protective glass is dirty. FIG. 8 is a flowchart showing the procedure for protecting the laser head. In addition, in FIGS. 5 to 7, the output signal of the temperature detector 31, which is the vertical axis, is converted into temperature.

[0053] First, the time response of the output signal of the temperature detector 31 will be described.

[0054] When the temperature of the laser head 50 rises to a predetermined temperature, if the temperature rises further, there is a risk of the laser head 50 burning out, as described above. To prevent this burning out, for example, the controller 70 stops the laser oscillation in the laser oscillator 80, and stops the laser light LB from being incident on the laser head 50. The temperature at this time is set as the oscillation stop set temperature Ts (hereinafter simply referred to as the set temperature Ts or the first threshold value Ts).

[0055] On the other hand, the output signal of the temperature detector 31 is converted into a temperature by the calculation unit 34 at regular intervals S. As shown in Fig. 5, if the actual temperature of the protective glass 41 reaches the set temperature Ts immediately after the output signal of the temperature detector 31 is converted into a temperature, the laser oscillation continues at least until the next temperature conversion timing, and the temperature of the protective glass 41, and therefore the laser head 50, overshoots and becomes higher than the set temperature Ts.

[0056] The degree of this overshoot depends on the degree of dirt on the surface of the protective glass 41. The greater the amount of debris adhering to the surface of the protective glass 41, the greater the amount of overshoot, in other words, the amount of temperature change in the laser head 50 in a certain period (cycle S) (hereinafter referred to as the temperature change ΔT (see FIG. 6)).

[0057] Therefore, as shown in FIG. 7, if the temperature change amount of the laser head 50 when there is no dirt on the protective glass 41 is the temperature change amount ΔTs, the temperature change amount ΔT of the laser head 50 when there is dirt on the protective glass 41 is greater than the temperature change amount ΔTs.

[0058] By utilizing this, the degree of dirt on the protective glass 41 can be indirectly evaluated based on the temperature T and the temperature change amount ΔT. Also, the degree of temperature rise of the laser head 50 can be predicted. For example, the temperature detector 31 measures the time change in the temperature of the laser head 50, and when the temperature change amount ΔT satisfies the relationship shown in formula (1), the controller 70 stops the laser oscillation in the laser oscillator 80. Note that the constant α is a value that satisfies α≧0 and is set appropriately. In the following description, (ΔTs+α) may be referred to as a second threshold value.

[0059] ΔT > ΔTs + α (1) Based on the above, a procedure for protecting the laser head 50 in this embodiment will be described with reference to FIG.

[0060] First, a laser oscillation command is output from the controller 70 to the laser oscillator 80 (step S1).

[0061] Next, the calculation unit 34 determines whether the state detection circuit 30 is in an open state or a closed state (step S2). In practice, the calculation unit 34 determines whether the shield unit 40 is properly attached to the housing 51 based on the output signal of the insertion detection switch 32.

[0062] If the determination result in step S2 is the closed state, in other words, if it is determined that the shield unit 40 is correctly attached to the housing 51, the process proceeds to step S3. On the other hand, if the determination result in step S2 is the open state, in other words, if it is determined that the shield unit 40 is not correctly attached to the housing 51, the calculation unit 34 outputs a first error signal as an insertion error signal to the controller 70 (step S9), and the controller 70 stops laser oscillation in the laser oscillator 80 (step S12).

[0063] In step S3, a laser oscillation command is received and laser oscillation is started by the laser oscillator 80. The generated laser light LB is guided to the laser head 50 through the optical fiber 90.

[0064] After executing step S3, the calculation unit 34 converts the output signal of the temperature detector 31 into a temperature and measures the temperature T of the laser head 50 (step S4). The calculation unit 34 also derives the temperature change amount ΔT every time a period S elapses (step S5). Note that steps S4 and S5 are actually executed in parallel by the calculation unit 34.

[0065] Next, the calculation unit 34 determines whether the temperature change amount ΔT derived in step S5 satisfies the relationship shown in equation (1), in other words, whether the temperature change amount ΔT exceeds a second threshold value (=ΔTs+α) (step S6).

[0066] If the result of the determination in step S6 is negative, that is, if the temperature change amount ΔT does not exceed the second threshold value, it is determined that there is a low possibility that the temperature of the laser head 50 will rise rapidly and cause burning or the like. In this case, the process proceeds to step S7.

[0067] On the other hand, if the result of the determination in step S6 is positive, that is, if it is determined that the temperature change amount ΔT exceeds the second threshold value and there is a high possibility that the laser head 50 will be burned or the like, the calculation unit 34 outputs a second error signal as a temperature error signal to the controller 70 (step S10). When the second error signal is input, the controller 70 stops the laser oscillation in the laser oscillator 80 (step S13).

[0068] The calculation unit 34 further determines whether or not the temperature T derived in step S4 exceeds a first threshold value (=Ts) (step S7). Note that step S7 may be executed before step S6.

[0069] If the determination result in step S7 is negative, that is, if the temperature T does not exceed the first threshold value, it is determined that there is a low risk of the laser head 50 burning out, etc. In this case, the process proceeds to step S8.

[0070] On the other hand, if the result of the determination in step S7 is positive, that is, if it is determined that the temperature T exceeds the first threshold value and there is a high possibility that the laser head 50 will be burned out or the like, the calculation unit 34 outputs a second error signal as a temperature error signal to the controller 70 (step S11). When the second error signal is input, the controller 70 stops the laser oscillation in the laser oscillator 80 (step S13).

[0071] In step S8, the same determination as in step S2 is executed again. That is, if the determination result in step S8 is the closed state, the process proceeds to step S9, where the irradiation of the laser light LB continues. Furthermore, the process returns to step S4, and a series of processes are repeated until the predetermined laser processing is completed.

[0072] On the other hand, if the determination result in step S8 is the open state, the calculation unit 34 outputs a first error signal as an insertion error signal to the controller 70 (step S12), and the controller 70 stops laser oscillation in the laser oscillator 80 (step S13).

[0073] During use of the laser processing apparatus 100, the laser head 50 moves along the weld line on the workpiece W. If the moving speed during this movement is too high, the mounting state of the shield unit 40 relative to the housing 51 may change. Also, if an impact is applied to the laser head 50 during movement, the mounting state of the shield unit 40 relative to the housing 51 may change. In step S8, it is checked again whether such a change in the mounting state has occurred during laser processing.

[0074] After the laser oscillation is stopped in step S13, the entire laser processing apparatus 100 is stopped and the cause of the error is investigated and inspected. For example, if the cause of the temperature error is dirt on the protective glass 41, the protective glass 41 is cleaned or replaced. Alternatively, the entire shield unit 40 is replaced.

[0075] [Effects, etc.] As described above, the laser head 50 according to this embodiment irradiates the received laser light LB toward the workpiece W. The laser head 50 at least includes a housing 51 having a plurality of optical components therein, a shield unit 40, and a state detection circuit 30.

[0076] The state detection circuit 30 detects the state regarding the temperature of the laser head 50 and the mounting state of the shield unit 40 to the housing 51. The state detection circuit 30 has at least a temperature detector 31, an insertion detection switch 32, and a calculation unit .

[0077] The shield unit 40 is detachably attached to the housing 51, and has a protective glass 41 and a holder 42 that holds the protective glass 41.

[0078] A temperature detector 31 for detecting the temperature of the laser head 50 is attached to the holder 42. The temperature detector 31 is disposed in the vicinity of the protective glass 41.

[0079] An insertion detection switch 32 that detects the attachment state of the shield unit 40 to the housing 51 is attached to the housing 51 .

[0080] The calculation unit 34 calculates the temperature of the laser head 50 based on the output signal of the temperature detector 31. The temperature detector 31 and the insertion detection switch 32 are connected in series.

[0081] According to this embodiment, the simple configuration can reliably suppress the temperature rise of the laser head 50. This makes it possible to prevent the laser head 50 from being burned out or the like.

[0082] As described above, if any debris adheres to the protective glass 41, the debris absorbs the laser light LB. Therefore, while the laser light LB is being emitted from the laser head 50, the protective glass 41 becomes the location inside the laser head 50 that generates the most heat.

[0083] On the other hand, according to the present embodiment, the temperature detector 31 is disposed on the holder 42 that holds the protective glass 41, and the temperature of the holder 42 is directly measured. Therefore, before the temperature of the entire laser head 50 rises, the irradiation of the laser light LB onto the workpiece W can be stopped based on the temperature measured by the temperature detector 31. This also makes it possible to prevent the laser head 50 from being burned out or the like.

[0084] In addition, there is no risk of problems with the conventional configurations shown in Patent Documents 1 to 4, such as a decrease in the processing quality of the workpiece W or insufficient penetration depth. It is possible to apply the state detection circuit 30 and the laser head 50 shown in this embodiment to the conventional configurations shown in Patent Documents 1 to 4.

[0085] In addition, as shown in FIG. 1, when performing laser processing by attaching the laser head 50 to the manipulator 60, which is a multi-joint axis robot, the signal lines 72a and 72b connecting the controller 70 and the laser head 50 become long. Usually, the length of these signal lines exceeds 1 m. In addition, the cable that houses the signal lines 72a and 72b bends when the laser head 50 moves, but it is necessary to balance flexibility and strength so that the internal signal lines do not break. However, if the number of wires housed inside increases, the cable becomes thicker, which hinders miniaturization of the laser head 50.

[0086] For example, if the temperature detector 31 and the insertion detection switch 32 are connected to the board box 20 and further to the controller 70 via their own signal lines, the above-mentioned cables will become thick.

[0087] On the other hand, according to this embodiment, by connecting the temperature detector 31 and the insertion detection switch 32 in series in the state detection circuit 30, it is possible to reduce the number of signal lines connecting the controller 70 and the laser head 50. This prevents the cable from becoming thicker, and makes it possible to miniaturize the laser head 50. This effect is remarkable when the manipulator 60 is a small or medium-sized robot.

[0088] Furthermore, according to this embodiment, the space required for the state detection circuit 30 can be reduced, and the manufacturing cost of the laser head 50 including the state detection circuit 30 can be reduced.

[0089] The shield unit 40 is preferably provided with electrical contacts 33a, 33b between the temperature detector 31 and the insertion detection switch 32. In this way, the temperature detector 31 and the insertion detection switch 32 can be reliably electrically connected to each other.

[0090] Moreover, it is preferable that the electrical contacts 33a and 33b are thermally separated from the heat generating portion of the shield unit 40, that is, from the protective glass 41. In this way, it is possible to suppress the flow of heat into the insertion detection switch 32 via the electrical contacts 33a and 33b, which would cause fluctuations in the operating characteristics of the insertion detection switch 32.

[0091] Furthermore, as shown in this embodiment, when a thermocouple is used as the temperature detector 31, the thermocouple is usually connected to the calculation unit 34 of the substrate box 20 via a compensation conductor. The compensation conductor is a conductor made of a metal having thermoelectromotive force characteristics almost equivalent to those of the thermocouple. If there is a temperature difference between the connection point between the thermocouple and the compensation conductor and the connection point between the compensation conductor and the substrate box 20, the temperature difference is compensated for by the compensation conductor.

[0092] In this embodiment, both ends of the temperature detector 31, which is a thermocouple, are connected to electrical contacts 33a, 33b, and the electrical contacts 33a, 33b are thermally isolated from the protective glass 41. Therefore, even if the compensation conductor is used only inside the shield unit 40, the output signal of the temperature detector 31 does not fluctuate significantly, and the difference between the temperature calculated by the calculation unit 34 and the actual temperature of the shield head 50 can be reduced. Note that it is preferable to use a conductor with a small wire diameter for the compensation conductor in order to reduce the heat capacity.

[0093] In addition, when a thermocouple is used as the temperature detector 31, the response speed can be increased, so that even if the temperature of the laser head 50 rises suddenly, this can be reliably detected and damage such as burning of the laser head 50 can be prevented.

[0094] Moreover, it is preferable that the calculation unit 34 corrects the calculated temperature of the laser head 50 in accordance with the length of the compensation lead. As described above, in this embodiment, the compensation lead is provided only inside the shield unit 40. For this reason, the length of the compensation lead may not be sufficient to compensate for the temperature difference between the connection point between the thermocouple and the compensation lead and the connection point between the compensation lead and the board box 20.

[0095] In such a case, if the calculation unit 34 corrects the temperature of the laser head 50 in accordance with the length of the compensation conductor, the accuracy of calculation of the temperature of the laser head 50 can be improved.

[0096] Furthermore, the calculation unit 34 determines whether or not the shield unit 40 is correctly attached to the housing 51, based on the output signal of the insertion detection switch 32. If the determination result is negative, the calculation unit 34 outputs a first error signal as an insertion error signal.

[0097] If the shield unit 40 is not properly attached to the housing 51, there is a risk that flying debris such as spatter and fumes may get inside the housing 51 and adhere to optical components such as the collimation lens 10 and the focus lens 11. If this occurs, not only will irradiation of the laser light LB onto the workpiece W be hindered, but the adhered flying debris may absorb the laser light LB, causing the optical components to heat up and become damaged.

[0098] According to this embodiment, the calculation unit 34 outputs a first error signal and notifies the controller 70 or an alarm unit (not shown) of the insertion error, so that a processing worker or the like can reliably recognize that the above-mentioned problem may occur.

[0099] The calculation unit also determines whether or not the temperature change amount ΔT of the laser head 50 in the predetermined period has exceeded a second threshold value (=ΔTs+α) based on the output signal of the temperature detector 31. Note that the predetermined period in this embodiment corresponds to the aforementioned cycle S.

[0100] If the determination result is positive, the calculation unit 34 outputs a second error signal as a temperature error signal.

[0101] When the temperature change amount ΔT exceeds the second threshold value, it is considered to be a sign that the dirt on the protective glass 41 is rapidly progressing. If this state continues, the temperature of the laser head 50 may rise rapidly, which may cause burning or the like.

[0102] Therefore, as shown in this embodiment, when the temperature change amount ΔT exceeds the second threshold value, the calculation unit 34 outputs a second error signal and notifies the controller 70 or an alarm unit (not shown) of the temperature error, so that a processing worker or the like can reliably recognize that the above-mentioned problem may occur.

[0103] Furthermore, the calculation unit 34 determines, based on the output signal of the temperature detector 31, whether or not the temperature of the laser head 50 has exceeded a first threshold value (=Ts).

[0104] If the determination result is positive, the calculation unit 34 outputs a second error signal as a temperature error signal.

[0105] If the temperature T exceeds the first threshold value, it is considered that the protective glass 41 is already dirty and the temperature of the laser head 50 exceeds the allowable value. In this case, there is a risk that the laser head 50 may be burned out.

[0106] Therefore, as shown in this embodiment, when the temperature T exceeds the first threshold value, the calculation unit 34 outputs a second error signal and notifies the controller 70 or an alarm unit (not shown) of the temperature error, so that the processing worker, etc. can reliably recognize that the above-mentioned problem may occur.

[0107] The laser processing apparatus 100 according to this embodiment at least includes a laser oscillator 80 that generates laser light LB, a laser head 50, and a controller 70 that controls the operation of at least the laser oscillator 80.

[0108] By configuring the laser processing apparatus 100 in this manner, it is possible to perform laser processing while monitoring the temperature of the laser head 50 and the mounting state of the shield unit 40 relative to the housing 51.

[0109] When the controller 70 receives the first error signal or the second error signal output from the calculation unit 34, the controller 70 stops the laser head 50 from irradiating the workpiece W with the laser light LB.

[0110] Furthermore, when the controller 70 receives the second error signal output from the calculation unit 34, the controller 70 stops the laser oscillation in the laser oscillator 80.

[0111] When the controller 70 receives the first error signal or the second error signal, it is estimated that the temperature of the laser head 50 will rise, causing the internal optical components or the laser head 50 itself to burn out.

[0112] In this embodiment, in such a case, the controller 70 stops the laser oscillation in the laser oscillator 80, thereby preventing the temperature of the laser head 50 from increasing.

[0113] In particular, when the controller 70 receives the second error signal, since the temperature of the laser head 50 has already risen, it is preferable to stop the laser oscillation and allow the temperature of the laser head 50 to decrease.

[0114] The method for protecting the laser head 50 according to this embodiment includes at least the following first to sixth steps.

[0115] In the first step, before the laser light LB is irradiated onto the workpiece W, the calculation unit 34 determines whether the state detection circuit 30 is in an open state or a closed state (step S2 in FIG. 8). More specifically, the calculation unit 34 determines whether the shield unit 40 is correctly attached to the housing 51.

[0116] In a second step, irradiation of the workpiece W with the laser light LB is started (step S3 in FIG. 8).

[0117] In a third step, the temperature detector 31 measures the temperature T of the laser head 50 (step S4 in FIG. 8).

[0118] In a fourth step, the calculation unit 34 derives the amount of temperature change ΔT of the laser head 50 during a predetermined period based on the output signal of the temperature detector 31 (step S5 in FIG. 8).

[0119] In a fifth step, the calculation unit 34 determines whether the temperature change amount ΔT exceeds a second threshold value (step S6 in FIG. 8).

[0120] In a sixth step, the calculation unit 34 determines whether or not the temperature T has exceeded the first threshold value (step S7 in FIG. 8).

[0121] In the first step, if the state detection circuit 30 is in a closed state, the processing from the second step onwards is continued, and if it is in an open state, the irradiation of the laser light LB to the workpiece W is stopped (step S13 in FIG. 8).

[0122] If the determination result in the fifth step is positive, that is, if the temperature change amount ΔT exceeds the second threshold value, the irradiation of the laser light LB onto the workpiece W is stopped (step S13 in FIG. 8).

[0123] If the determination result in the sixth step is positive, that is, if the temperature T exceeds the first threshold value, the irradiation of the laser light LB onto the workpiece W is stopped (step S13 in FIG. 8).

[0124] If the determination results in both the fifth step and the sixth step are negative, irradiation of the workpiece W with the laser light LB continues (step S9 in FIG. 8).

[0125] In this way, it is possible to reliably suppress a rise in temperature of the laser head 50. This makes it possible to prevent the laser head 50 from being burned out and to protect the laser head 50.

[0126] This method for protecting the laser head 50 may further include a seventh step.

[0127] In the seventh step, after the sixth step is executed, the calculation unit 34 determines whether the state detection circuit 30 is in the open state or the closed state, similarly to the first step (step S8 in FIG. 8).

[0128] In the seventh step, if the state detection circuit 30 is in a closed state, irradiation of the laser light LB onto the workpiece W is continued (step S9 in FIG. 8), and if it is in an open state, irradiation of the laser light LB onto the workpiece W is stopped (step S13 in FIG. 8).

[0129] By providing the seventh step, even if the mounting state of the shield unit 40 relative to the housing 51 changes due to an impact being applied to the laser head 50 during laser processing, this can be reliably detected, and the laser head 50 can be protected by preventing burning or the like of the laser head 50.

[0130] (Embodiment 2) In the first embodiment, an example in which a thermocouple is used as the temperature detector 31 has been described, but the temperature detector 31 may be another type of element. For example, the temperature detector 31 may be a resistor for measuring temperature, or may be a thermostat using a bimetal.

[0131] In the latter case, it is only possible to detect whether the temperature of the laser head 50 has exceeded a predetermined threshold value, but it is useful in preventing a risk of temperature rise in the laser head 50 and, ultimately, burning out of the laser head 50. The threshold value in this case may be the same as the set temperature Ts shown in the first embodiment. Also, in consideration of the operational stability of the temperature detector 31, the threshold value may be a value lower than the set temperature Ts.

[0132] FIG. 9 is a flow chart showing a procedure for protecting the laser head according to the second embodiment, in which the temperature detector 31 is a thermostat using a bimetal.

[0133] Steps S21 to S23, S26 to S28, and S30 shown in FIG. 9 are similar to steps S1 to S3, S8 to S10, and S13 shown in FIG. 8, respectively, and therefore will not be described.

[0134] Furthermore, in the flow chart shown in Fig. 9, steps S5 and S6 shown in Fig. 8 are omitted because the temperature detector 31 of this embodiment cannot evaluate the amount of temperature change ΔT.

[0135] Also, in Fig. 9, for convenience of explanation, step S24 and step S25 are distinguished, but in reality, they are one process. That is, the temperature T of the laser head 50 is measured by the temperature detector 31, and if the temperature T is equal to or lower than the threshold value, the bimetal contacts maintain their initial state. If the temperature T exceeds the threshold value, the state changes. If the contacts are initially in contact, they open when the temperature T exceeds the threshold value. If the contacts are initially open, they make contact when the temperature T exceeds the threshold value.

[0136] Furthermore, if the temperature T exceeds the threshold value in step S25, the calculation unit 34 outputs a third error signal (step S29).

[0137] Also, as shown in FIG. 9, if in step S28 the calculation unit 34 determines that the shield unit 40 is not correctly attached to the housing 51 based on the output signal of the insertion detection switch 32, the calculation unit 34 outputs a third error signal (step S29).

[0138] In other words, in the laser head 50 of this embodiment, the calculation unit 34 determines whether the state detection circuit 30 is in a closed state or an open state. If the state detection circuit 30 is in an open state, the calculation unit 34 outputs a third error signal.

[0139] In addition, in the laser head 50 of this embodiment, if a third error signal is output during the period in which the laser head 50 is irradiating the laser light LB, the calculation unit 34 determines that the temperature of the laser head 50 exceeds a predetermined threshold value.

[0140] On the other hand, if the third error signal is output during a period in which the laser head 50 is not irradiating the laser light LB, the calculation unit 34 determines that the shield unit 40 is not attached to the housing 51 correctly.

[0141] Furthermore, in the laser processing apparatus 100, when the controller 70 receives the third error signal output from the calculation unit 34, the controller 70 stops the irradiation of the laser light LB from the laser head 50 to the workpiece W. Specifically, the controller 70 stops the laser oscillation in the laser oscillator 80.

[0142] According to this embodiment, it is possible to achieve the same effect as that achieved by the configuration shown in the first embodiment. That is, it is possible to reliably suppress the temperature rise of the laser head 50. This makes it possible to prevent the laser head 50 from being burned out and to protect the laser head 50.

[0143] Furthermore, by the controller 70 stopping the laser oscillation in the laser oscillator 80, it is possible to prevent the temperature of the laser head 50 from increasing, and in turn the laser head 50 from being burned out or the like.

[0144] Moreover, it is possible to easily determine whether the third error signal is an insertion error signal or a temperature error signal from the output timing of the third error signal and the generation state of the laser light LB. In this way, the number of types of signals output from the calculation unit 34 can be reduced.

[0145] Moreover, the method for protecting the laser head 50 of the present embodiment includes at least the following eighth to twelfth steps.

[0146] In an eighth step (step S22 in FIG. 9), before the workpiece W is irradiated with the laser light LB, it is determined whether the state detection circuit 30 is in an open state or a closed state.

[0147] In a ninth step (step S23 in FIG. 9), irradiation of the workpiece W with the laser light LB begins.

[0148] In a tenth step (step S24 in FIG. 9), the temperature detector 31 measures the temperature of the laser head 50.

[0149] In an eleventh step (step S25 in FIG. 9), it is determined whether or not the temperature T of the laser head 50 has exceeded a threshold value.

[0150] In a twelfth step (step S26 in FIG. 9), after execution of the eleventh step, it is determined whether the state detection circuit 30 is in an open state or a closed state.

[0151] In the eighth step, if the state detection circuit 30 is in a closed state, the processing continues from the ninth step onwards, and if the state detection circuit 30 is in an open state, the irradiation of the laser light LB to the workpiece W is stopped (step S30).

[0152] If the determination result in step 11 is positive, that is, if the temperature T of the laser head 50 exceeds the threshold value, the irradiation of the laser light LB to the workpiece W is stopped. On the other hand, if the determination result in step 11 is negative, that is, if the temperature T of the laser head 50 does not exceed the threshold value, step 12 is executed.

[0153] In the twelfth step, if it is determined that the state detection circuit 30 is in the closed state, the irradiation of the laser light LB to the workpiece W is continued (step S27). If it is determined that the state detection circuit 30 is in the open state, the irradiation of the laser light LB to the workpiece W is stopped (step S27).

[0154] According to this embodiment, it is possible to achieve the same effect as the method shown in the first embodiment. That is, it is possible to reliably suppress the temperature rise of the laser head 50. This makes it possible to prevent the laser head 50 from burning out and protect the laser head 50. In addition, by stopping the laser oscillation of the laser oscillator 80, it is possible to prevent the temperature rise of the laser head 50 and, in turn, the occurrence of the laser head 50 being burned out.

[0155] The temperature detector 31 used in this embodiment may be of any structure capable of detecting whether the temperature T of the laser head 50 has exceeded a threshold value, and may be the resistor or shape memory alloy described above.

[0156] (Other embodiments) In the first embodiment, the temperature detector 31 is attached to the shield unit 40 arranged on the side closer to the light exit port 51b. However, this is not particularly limited, and the temperature detector 31 may be attached to the shield unit 40 arranged on the side farther from the light exit port 51b. Furthermore, the temperature detector 31 may be attached to both shield units 40. [Industrial Applicability]

[0157] The laser head of the present disclosure is useful because it can reliably suppress an increase in temperature of itself with a simple configuration. [Explanation of symbols]

[0158] 10 Collimation Lens 11 Focus Lens 20 PCB Box 30 Status detection circuit 31 Temperature detector 32 Insertion detection switch 33a, 33b Electrical contacts 34 Arithmetic section 40 Shield Unit 41 Protective Glass 42 Holder 50 Laser Head 51 Case 51a Light entrance 51b Light exit port 60 Manipulator 70 Controller 80 Laser Oscillator 90 Optical Fiber 100 Laser processing equipment LB laser light W work

Claims

1. A laser head including at least a housing having a plurality of optical components therein and a shield unit detachably attached to the housing, the laser head irradiating a received laser light toward a workpiece, the laser head further includes a state detection circuit that detects a state related to a temperature of the laser head and an attachment state of the shield unit to the housing, The shield unit includes a protective glass and a holder that holds the protective glass. a temperature detector for detecting a temperature of the laser head is attached to the holder; an insertion detection switch is attached to the housing to detect an attachment state of the shield unit to the housing; the temperature detector is attached near the protective glass; the state detection circuit includes at least the temperature detector, the insertion detection switch, and a calculation unit; The calculation unit calculates a temperature of the laser head based on an output signal of the temperature detector, The laser head is characterized in that the temperature detector and the insertion detection switch are connected in series.

2. 2. The laser head according to claim 1, the shield unit is provided with electrical contacts between the temperature detector and the insertion detection switch, 4. A laser head according to claim 1, wherein the electrical contact is thermally isolated from a heat generating portion of the shield unit.

3. 3. The laser head according to claim 2, the temperature detector is a thermocouple, 4. A laser head according to claim 1, wherein the thermocouple is electrically connected to the electrical contact via a compensation conductor.

4. 4. The laser head according to claim 3, The laser head according to the present invention, wherein the calculation unit corrects the calculated temperature of the laser head in accordance with the length of the compensation conductor.

5. 2. The laser head according to claim 1, the calculation unit determines whether or not the shield unit is properly attached to the housing based on an output signal of the insertion detection switch; When the determination result is negative, the calculation unit outputs a first error signal.

6. 6. The laser head according to claim 5, The calculation unit determines whether or not the temperature of the laser head has exceeded a first threshold value based on an output signal of the temperature detector, When the determination result is positive, the calculation unit outputs a second error signal.

7. 7. The laser head according to claim 6, The calculation unit determines whether or not a temperature change amount of the laser head in a predetermined period of time exceeds a second threshold value based on an output signal of the temperature detector, When the determination result is positive, the calculation unit outputs a second error signal.

8. 2. The laser head according to claim 1, The calculation unit determines whether the state detection circuit is in a closed state or an open state, 4. The laser head according to claim 1, wherein, when the state detection circuit is in the open state, the calculation unit outputs a third error signal.

9. 9. The laser head according to claim 8, When the third error signal is output during a period in which the laser head is irradiating the laser light, the calculation unit determines that the temperature of the laser head exceeds a predetermined threshold value, A laser head characterized in that when the third error signal is output during a period when the laser light is not being irradiated from the laser head, the calculation unit determines that the shield unit is not properly attached to the housing.

10. a laser oscillator that generates the laser light; A laser head according to claim 6 or 7; and a controller for controlling the operation of at least the laser oscillator.

11. 11. The laser processing apparatus according to claim 10, When the controller receives the second error signal output from the calculation unit, The laser processing apparatus is characterized in that the controller stops laser oscillation in the laser oscillator.

12. a laser oscillator that generates the laser light; A laser head according to claim 8 or 9; and a controller for controlling the operation of at least the laser oscillator.

13. 13. The laser processing apparatus according to claim 12, When the controller receives the third error signal output from the calculation unit, The laser processing apparatus is characterized in that the controller stops laser oscillation in the laser oscillator.

14. 2. A method for protecting a laser head according to claim 1, comprising: a first step of determining whether the state detection circuit is in an open state or a closed state before irradiating the workpiece with the laser light; a second step of starting irradiation of the laser light onto the workpiece; a third step of measuring a temperature of the laser head by the temperature detector; a fourth step of deriving a temperature change amount of the laser head during a predetermined period based on an output signal of the temperature detector; a fifth step of determining whether the temperature change amount exceeds a second threshold value; and a sixth step of determining whether the temperature of the laser head exceeds a first threshold value, In the first step, if the state detection circuit is in the closed state, the processing from the second step onwards is continued, and if the state detection circuit is in the open state, the irradiation of the laser light to the workpiece is stopped; When either the determination result of the fifth step or the determination result of the sixth step is positive, the irradiation of the laser light onto the workpiece is stopped; A method for protecting a laser head, characterized in that if both the judgment results of the fifth step and the sixth step are negative, irradiation of the laser light to the workpiece is continued.

15. The method for protecting a laser head according to claim 14, A seventh step of determining whether the state detection circuit is in the open state or the closed state after the sixth step is executed, A method for protecting a laser head, characterized in that, in the seventh step, if it is determined that the status detection circuit is in the closed state, irradiation of the laser light to the workpiece is continued, and if it is determined that the status detection circuit is in the open state, irradiation of the laser light to the workpiece is stopped.

16. A method for protecting a laser head according to claim 8, comprising the steps of: The temperature detector detects whether the temperature of the laser head exceeds a predetermined threshold value; an eighth step of determining whether the state detection circuit is in the open state or the closed state before irradiating the workpiece with the laser light; A ninth step of starting irradiation of the laser light onto the workpiece; a tenth step of measuring a temperature of the laser head by the temperature detector; an eleventh step of determining whether the temperature of the laser head exceeds the threshold; and a twelfth step of determining whether the state detection circuit is in the open state or the closed state after the eleventh step is executed, In the eighth step, if the state detection circuit is in the closed state, the processing from the ninth step onwards is continued, and if the state detection circuit is in the open state, the irradiation of the laser light to the workpiece is stopped; When the determination result of the eleventh step is positive, the irradiation of the laser light to the workpiece is stopped, and when the determination result of the eleventh step is negative, the twelfth step is executed; A method for protecting a laser head, characterized in that, in the twelfth step, if it is determined that the status detection circuit is in the closed state, irradiation of the laser light to the workpiece is continued, and if it is determined that the status detection circuit is in the open state, irradiation of the laser light to the workpiece is stopped.

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