Laser Processing System

Abstract

To detect abnormality of a sensor which detects oxygen concentration before processing start.SOLUTION: A laser processing system comprises: a laser device 11 which irradiates a workpiece 2 with laser light; a shield gas nozzle 12 which injects shield gas into the workpiece 2 irradiated with the laser light by the laser device 11; a shield gas supply part 13 which supplies the shield gas nozzle 12 with shield gas while receiving air supply from outside; a sensor 14 which can measures oxygen concentration of the shield gas supplied from the shield gas supply part 13 to the shield gas nozzle 12, and oxygen concentration of the air supplied from outside; and a bypass passage 24 which supplies the sensor 14 with air without using the shield gas supply part 13. Before processing the workpiece 2 by use of the laser device 11, the sensor 14 measures oxygen concentration of the air supplied from the bypass passage 24 to perform operation confirmation of the sensor 14.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a laser processing system that performs processing by irradiating a workpiece with laser light. [Background technology]

[0002] Laser clad processing is known as a method of precision welding. A conventional technology in this field is disclosed in JP2017-056480A. In laser clad processing, a shielding gas is used to stabilize the molten pool at the processing point when melting powder with a laser and to suppress the rise in the molten pool temperature.

[0003] Here, if the concentration of the shielding gas decreases, i.e., if the oxygen concentration increases, it may cause quality defects such as damage to equipment due to fumes and cladding cracking. Therefore, the shielding gas must maintain a required purity, and oxygen concentration sensors are used as a means of guaranteeing purity. In particular, when using shielding gas with an oxygen concentration of 1% or less during laser processing, zirconia-type oxygen concentration sensors are generally used. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2017-056480 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the case of the zirconia-type oxygen concentration sensor used in the conventional laser cladding process described above, when it is used continuously, a film is formed on the electrode due to the silicon-based gas contained in trace amounts in the air, which causes the sensor to lose its function and result in detection failure.

[0006] In particular, when a film is formed on the electrode surface as shown in Fig. 3, even if the oxygen concentration in the shielding gas is high, erroneous detection of a low oxygen concentration is likely to occur. Here, when the oxygen concentration in the shielding gas becomes high, machining defects in the workpiece, such as oxidation of the surface and inappropriate build-up shapes, are likely to occur.

[0007] Furthermore, damage may accumulate in the laser processing equipment due to the growth of fumes generated at the processing point of the workpiece and spatters adhering to the shielding gas nozzle as shown in Figure 4, which may ultimately lead to processing defects of the workpiece. Therefore, there has been a demand to reduce the occurrence of false detection of oxygen concentration caused by oxygen concentration sensors and prevent processing defects before they occur. The present invention provides a laser processing system that detects an abnormality in a sensor for detecting an oxygen concentration before processing begins. [Means for solving the problem]

[0008] The laser processing system of the present invention comprises a laser device that irradiates a workpiece with laser light, a shielding gas nozzle that sprays shielding gas toward the workpiece irradiated with laser light by the laser device, a shielding gas supply unit that receives an air supply from an outside and supplies the shielding gas to the shielding gas nozzle, a sensor that can measure the oxygen concentration of the shielding gas supplied from the shielding gas supply unit to the shielding gas nozzle and the oxygen concentration of air supplied from the outside, and a bypass passage that supplies air to the sensor without passing through the shielding gas supply unit, and before processing the workpiece using the laser device, the oxygen concentration of the air that has passed through the bypass passage is measured with the sensor to confirm the operation of the sensor. This makes it possible to perform an operation for detecting whether or not the sensor is correctly measuring the oxygen concentration before the start of processing. Effect of the Invention

[0009] This makes it possible to detect an abnormality in the sensor for detecting the oxygen concentration before processing begins. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of a laser processing system. [Diagram 2] FIG. 2 is a diagram showing a flow of a preparation stage and a processing stage by the laser processing system. [Diagram 3] FIG. 13 is a diagram showing an example of a state in which a false detection occurs in an associated sensor. [Figure 4] FIG. 1 illustrates an example of a state in which a fault occurs in a related shielding gas nozzle. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will now be described with reference to the drawings. Fig. 1 is a diagram showing an example of the configuration of a laser processing system 1. As shown in Figs.

[0012] The laser processing system 1 includes a laser device 11 that irradiates the workpiece 2 with a laser, a shielding gas nozzle 12 that sprays a shielding gas, a shielding gas supply unit 13 that supplies shielding gas to the shielding gas nozzle 12, a sensor 14 that measures the oxygen concentration of the gas supplied to the shielding gas nozzle, a judgment unit 15 that judges the oxygen concentration measured by the sensor 14, an equipment control unit 16 that controls the continuation or stop of laser processing of the workpiece by the laser processing system 1 depending on the judgment result of the judgment unit 15, and a bypass passage 24.

[0013] The laser device 11 is a device that irradiates a laser beam. The laser device 11 irradiates the workpiece 2 with the laser beam in accordance with the control of the device control unit 16.

[0014] The shielding gas nozzle 12 is a nozzle that injects a shielding gas toward the workpiece 2 to be irradiated with laser light by the laser device 11. The shielding gas nozzle 12 is connected to a shielding gas supply unit 13 via a sensor 14.

[0015] As an example, the shielding gas nozzle 12 and the shielding gas supply unit 13 are connected via the sensor 14 by a pipe capable of transporting gas. Here, the pipe that is a gas passage connecting the shielding gas nozzle 12 and the sensor 14 is referred to as a first passage 21. Similarly, the pipe that connects the sensor 14 and the shielding gas supply unit 13 is referred to as a second passage 22. Note that a first valve 31 is provided in the first passage 21, and a second valve 32 is provided in the second passage 22.

[0016] The shielding gas supply unit 13 is a device that generates a shielding gas to be supplied to the shielding gas nozzle 12. A third passage 23, which is a pipe for supplying dry air (hereinafter, dry air) from the outside of the laser processing system 1, is connected to the shielding gas supply unit 13. A third valve 33 is provided in the third passage 23.

[0017] Furthermore, a bypass passage 24 is connected to the second passage 22 and the third passage 23, which connects the two pipes without passing through the shielding gas supply unit 13. Here, the end of the bypass passage 24 on the second passage 22 side is connected to the second passage 22 via a second valve 32. Similarly, the end of the bypass passage 24 on the third passage 23 side is connected to the third passage 23 via a third valve 33.

[0018] The sensor 14 may be a zirconia sensor that measures the oxygen concentration of the shielding gas or air inserted via the second passage 22. As will be described in detail later, in a preparation stage before processing in the laser processing system 1, the sensor 14 measures the oxygen concentration of dry air that is supplied from outside the laser processing system 1 and inserted into the second passage 22 via the bypass passage 24. Furthermore, in a processing stage in which actual processing is performed in the laser processing system 1, the sensor 14 measures the oxygen concentration of the shielding gas that is supplied from the shielding gas supply unit 13 via the second passage 22.

[0019] Here, the sensor 14 is connected to a first passage 21 which is a passage leading to the shielding gas nozzle 12, and is also connected to a second passage 22 which is a passage leading to the shielding gas supply unit 13. As will be described later, in the second passage 22, a second valve 32 is used to switch between the shielding gas supply unit 13 side and the bypass passage 24.

[0020] Further, the sensor 14 is connected to the determination unit 15. The sensor 14 outputs the measurement result of the oxygen concentration to the determination unit 15. For example, the output of the oxygen concentration information from the sensor 14 to the determination unit 15 is performed by an analog signal.

[0021] Here, the first valve 31, the second valve 32, and the third valve 33 will be described in more detail.

[0022] A first valve 31 is provided in the first passage 21 to change the state of gas supply to the shielding gas nozzle 12 in response to control from the equipment control unit 16. For example, the first valve 31 can switch between a state in which gas is supplied to the shielding gas nozzle 12 and a state in which the supply is stopped by switching the open / close state of the valve in response to a control instruction from the equipment control unit 16.

[0023] For example, when the laser processing system 1 is in the preparation stage and dry air is being inserted into the sensor 14, the first valve 31 can discharge the dry air after passing through the sensor 14 to the outside of the laser processing system 1 without passing it to the shielding gas nozzle 12 side.

[0024] The second passage 22 is provided with a second valve 32 that switches the gas supplied to the sensor 14 by changing its state in response to control from the equipment control unit 16. For example, the second valve 32 can switch the gas supplied to the sensor 14 between the gas supplied from the shielding gas supply unit 13 and the dry air supplied from the third passage 23 via the bypass passage 24.

[0025] The third passage 23 is provided with a third valve 33 which switches the supply destination of the dry air supplied from outside the laser processing system 1 by changing its state in response to control from the equipment control unit 16. For example, the third valve can switch the supply destination of the dry air between the shielding gas supply unit 13 and the sensor 14 by supplying the dry air to the second passage 22 via a bypass passage 24. Typically, the second valve 32 and the third valve 33 can be switched in conjunction with each other.

[0026] The determination unit 15 determines whether the sensor 14 is operating normally in the preparation stage before the start of processing, using the oxygen concentration information received from the sensor 14. In addition, the determination unit 15 outputs the determination result as to whether the sensor 14 is operating normally to the equipment control unit 16.

[0027] The device control unit 16 controls the operations of the laser device 11, the first valve 31, the second valve 32, and the third valve 33.

[0028] Specifically, in a preparation stage before the start of processing, the equipment control unit 16 controls the second valve 32 and the third valve 33 so that dry air supplied from outside the laser processing system 1 is introduced to the sensor 14 via the bypass passage 24 without passing through the shielding gas supply unit 13. Note that at this time, typically, dry air is not supplied to the shielding gas supply unit 13. Furthermore, at this time, the equipment control unit 16 controls the first valve 31 so that the dry air that has passed through the sensor 14 for measurement is discharged to the outside of the laser processing system 1.

[0029] On the other hand, in the processing stage, the equipment control unit 16 controls the second valve 32 and the third valve 33 so that dry air supplied from outside the laser processing system 1 is supplied to the shielding gas supply unit 13. At this time, the dry air typically does not pass through the bypass passage 24. Furthermore, at this time, the equipment control unit 16 controls the first valve 31 so that the shielding gas discharged from the shielding gas supply unit 13 is supplied to the shielding gas nozzle 12 via the sensor 14.

[0030] Furthermore, during the processing stage, when the oxygen concentration measured by the sensor 14 is determined to be high by the judgment unit 15, the equipment control unit 16 controls the laser device 11 to stop irradiating laser light, and also controls the operation of the first valve 31 to stop the spraying of shielding gas from the shielding gas nozzle 12.

[0031] The equipment control unit 16 is connected to the laser device 11, the first valve 31, the second valve 32, and the third valve 33 via signal lines, and can perform control by sending and receiving signals via the signal lines, but the method of sending and receiving signals is not limited to using signal lines.

[0032] Next, with reference to FIG. 2, an operational flow of the preparation stage and the processing stage in the laser processing system 1 will be described.

[0033] First, before starting processing (starting work), a preparation operation is performed in the laser processing system 1. In other words, in the laser processing system 1, a confirmation cycle of the sensor 14 is performed (S1).

[0034] Here, the laser processing system 1 checks whether the sensor 14 is normal or not (S2). Specifically, the equipment control unit 16 controls the second valve 32 and the third valve 33 to supply dry air from outside the laser processing system 1 through the bypass passage 24 to the sensor 14.

[0035] The sensor 14 measures the oxygen concentration of the dry air and transmits the measurement result to the determination unit 15. Here, the oxygen concentration of the dry air is known. Therefore, the determination unit 15 can determine whether the sensor 14 is normal or not from the oxygen concentration of the dry air measured by the sensor 14.

[0036] For example, in judgment unit 15, if sensor 14 can measure the oxygen concentration within a predetermined error range of several percent in the presence of a high oxygen concentration contained in dry air, it is determined that the measurement is normal, and if the measured value is outside the error range, it is determined that the measurement is abnormal.

[0037] If the judgment unit 15 judges that the sensor 14 is normal (normal in S2), the process proceeds to S4. If the judgment unit 15 judges that the sensor 14 is not able to measure the oxygen concentration normally and is in an abnormal state (abnormal in S2), the process proceeds to S3, where the sensor 14 is replaced, and then the process proceeds to S4.

[0038] Next, the laser processing system 1 starts a production stage (processing stage) in which laser processing is performed on the workpiece 2 (S4). At this time, the equipment control unit 16 controls the laser device 11, the first valve 31, the second valve 32, and the third valve 33.

[0039] Typically, the device control unit 16 controls the laser device 11 to start irradiating the workpiece with laser light.

[0040] Furthermore, the appliance control unit 16 operates the second valve 32 and the third valve 33 to close the path on the bypass passage 24 side, thereby controlling the bypass passage 24 to be in a state in which dry air does not flow therethrough.

[0041] Furthermore, the equipment control unit 16 operates the first valve 31 and performs control so that the shielding gas flows from the shielding gas supply unit 13 to the shielding gas nozzle 12.

[0042] As a result, dry air is supplied to the shielding gas supply unit 13 from outside the laser processing system 1, and shielding gas generated by the shielding gas supply unit 13 and discharged from the shielding gas supply unit 13 is supplied to the shielding gas nozzle 12.

[0043] Thereafter, if laser processing is continuously performed, a decrease in the concentration of the shielding gas may occur (S5).

[0044] Sensor 14 measures the oxygen concentration of the shielding gas supplied from shielding gas supply unit 13 to shielding gas nozzle 12. In this way, sensor 14 detects a decrease in the concentration of the shielding gas (S6).

[0045] For example, sensor 14 continuously measures the oxygen concentration during processing by laser processing system 1. Then, determination unit 15 determines that the oxygen concentration has increased by utilizing the measurement result by sensor 14. The determination in determination unit 15 can be performed in the same manner as in S2, for example, and can determine that the concentration of the shielding gas has decreased when the oxygen concentration has increased above a predetermined value.

[0046] In the laser processing system 1, the equipment is automatically stopped in response to the determination by the determining unit 15 that the concentration of the shielding gas has decreased (S7).

[0047] At this time, for example, the device control section 16 controls the laser device 11 to stop irradiating the workpiece with the laser light.

[0048] Furthermore, the equipment control unit 16 operates the first valve 31 to perform control so that the shielding gas does not flow from the shielding gas supply unit 13 to the shielding gas nozzle 12 .

[0049] Furthermore, the equipment control unit 16 operates the second valve 32 and the third valve 33 to control the supply of dry air to the shielding gas supply unit 13 to be stopped.

[0050] This allows the laser processing system 1 to be stopped.

[0051] Thereafter, maintenance of the laser processing system 1 is performed (S8). For example, the laser processing system 1 returns to the preparatory stage operation of S1, checks whether the operation of the sensor 14 is normal, and if an abnormality is found in the operation of the sensor 14, replaces the sensor 14, and then the processing process can be resumed.

[0052] Returning to S1, the process of detecting whether the sensor 14 is normal or not may be started automatically or may be performed manually.

[0053] Furthermore, the points to be checked in this maintenance process are not limited to the sensor 14, and other parts constituting the laser processing system 1 can also be checked.

[0054] In this way, the preparatory cycle for checking whether the sensor 14 is correctly measuring the oxygen concentration can be executed before the laser processing stage, and if there is an abnormality in the sensor 14, the abnormality can be detected before the start of the laser processing.

[0055] In addition, not only before the start of the processing stage but even when the processing stage is being performed, if there is a possibility that an abnormality has occurred in the sensor 14, it is possible to automatically or manually transition to a preparation process and inspect whether or not an abnormality has occurred in the sensor 14.

[0056] This reduces the possibility of erroneous detection of the oxygen concentration by the sensor 14 in the laser processing system 1. Therefore, processing defects caused by high oxygen concentrations can be prevented, and the occurrence of defective products can be suppressed.

[0057] The present invention is not limited to the above-described embodiment, and can be modified as appropriate without departing from the spirit of the present invention. In other words, the above description has been omitted or simplified as appropriate for the purpose of clarity, and a person skilled in the art can easily modify, add, or convert each element of the embodiment within the scope of the present invention. [Explanation of symbols]

[0058] 1 Laser processing system 2 Workpiece 11 Laser device 12 Shielding gas nozzle 13 Shielding gas supply section 14 Sensors 15 Judgment section 16 Equipment control section 21 First Passage 22 Second Passage 23 Third Passage 24 Bypass Passage 31 First Valve 32 Second Valve 33 Third Valve

Claims

[Claim 1] A laser device that irradiates a workpiece with laser light; a shield gas nozzle that injects a shield gas toward the workpiece irradiated with the laser light by the laser device; a shielding gas supply unit that receives air from an outside and supplies the shielding gas to the shielding gas nozzle; a sensor capable of measuring an oxygen concentration of the shielding gas supplied from the shielding gas supply unit to the shielding gas nozzle and an oxygen concentration of air supplied from an outside; a bypass passage for supplying air to the sensor without passing through the shielding gas supply unit; A determination unit; A device control unit, The determination unit is When the sensor measures the oxygen concentration of the air that has passed through the bypass passage to check the operation of the sensor before the workpiece is processed using the laser device, if the oxygen concentration can be measured within a predetermined error range in the presence of a high oxygen concentration contained in the air that has passed through the bypass passage, the sensor is determined to be normal, and if the measured value is outside the error range, the sensor is determined to be abnormal. The device control unit includes: If the result of the judgment by the judgment unit is normal, a valve is controlled so that air does not flow through the bypass passage and the shielding gas flows from the shielding gas supply unit. Laser processing system.

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