Abnormality determining device, laser processing machine, and abnormality determining method

Abstract

[Problem] To provide an abnormality determining device, a laser processing machine, and an abnormality determining method capable of accurately determining a processing abnormality with respect to a workpiece. [Solution] An abnormality determining device (3) for determining a processing abnormality on a workpiece W, the device comprising: a storage unit (41) that, when a moving unit (12) moves and a processing unit (20) performs normal processing on a workpiece W while moving with respect to the workpiece W, associates and stores a state quantity detected by a sensor unit (30) with a movement-related value acquired by an acquiring unit (40); a calculating unit (42) that calculates the normal range of a state quantity for each movement-related value on the basis of information stored in the storage unit (41); and a determining unit (43) that determines, on the basis of the calculation results by the calculating unit (42), whether the state quantity detected by the sensor unit (30) after the normal range has been calculated is within the normal range.

Description

Abnormality determination device, laser processing machine, and abnormality determination method

[0001] The present invention relates to an abnormality determination device, a laser processing machine, and an abnormality determination method.

[0002] A laser processing machine performs laser processing, such as cutting, on a workpiece by irradiating the workpiece with a laser beam while moving a laser head relative to the workpiece. It is required for the laser processing machine to perform laser processing on the workpiece appropriately. Therefore, it has been proposed that, when good processing quality is obtained in test processing or actual processing, an operator performs a predetermined operation to store a reference value for the laser output amount, and then performs laser processing based on this value (see, for example, Patent Document 1).

[0003] Special Publication No. 7-61553

[0004] In processing devices such as laser processing machines, sensors are sometimes installed to detect state quantities related to the processing of workpieces by the processing device in order to manage processing quality. The state quantities detected by the sensors are used to determine whether or not a processing abnormality has occurred on the workpiece based on whether or not the state quantities fall outside a predetermined normal range of state quantities (hereinafter referred to as the "normal range"). This normal range may be set wider (relaxed) depending on the operating status of the processing device. Widening the normal range can result in situations where a state that should be determined to be abnormal is not determined to be abnormal. Therefore, in order to improve the accuracy of determining processing abnormalities, it is desirable to obtain a more appropriate normal range. The above-mentioned patent document 1 simply performs laser processing based on a laser output reference value, and is unable to resolve the above-mentioned problems.

[0005] An object of the present invention is to provide an abnormality determination device, a laser processing machine, and an abnormality determination method that are capable of accurately determining machining abnormalities in a workpiece.

[0006] An abnormality determination device according to one aspect of the present invention is an abnormality determination device that determines abnormalities in the processing of a workpiece in a processing device having a moving unit that moves relative to a workpiece, and a processing unit that is provided on the moving unit and processes the workpiece while moving relative to the workpiece together with the moving unit, and is equipped with: a sensor unit that is provided on the moving unit and moves relative to the workpiece together with the moving unit while detecting state quantities related to the processing of the workpiece by the processing device; an acquisition unit that acquires movement relationship values ​​related to the movement of the moving unit; a storage unit that stores the state quantities detected by the sensor unit in correspondence with the movement relationship values ​​acquired by the acquisition unit when the processing unit moves relative to the workpiece in accordance with the movement of the moving unit and processes the workpiece normally; a calculation unit that calculates a normal range of the state quantities for each movement relationship value based on the information stored in the storage unit; and a judgment unit that, after the normal range has been calculated, determines whether the state quantities detected by the sensor unit are within the normal range based on the calculation result by the calculation unit when the processing unit moves relative to the workpiece in accordance with the movement of the moving unit and processes the workpiece.

[0007] A laser processing machine according to an aspect of the present invention includes a laser head that moves relative to a workpiece, a laser emission unit that is provided on the laser head and moves together with the laser head relative to the workpiece while emitting a laser beam to the workpiece to process the workpiece, and an abnormality determination device that determines abnormalities in processing of the workpiece. The abnormality determination device includes a sensor unit that is provided on the laser head and moves together with the laser head relative to the workpiece while detecting state quantities of the laser processing machine, an acquisition unit that acquires movement relationship values ​​related to the movement of the laser head, a storage unit that associates the state quantities detected by the sensor unit with the movement relationship values ​​acquired by the acquisition unit when the laser emission unit moves relative to the workpiece in accordance with the movement of the laser head to process the workpiece normally, and stores the state quantities detected by the sensor unit in correspondence with the movement relationship values ​​acquired by the acquisition unit, a calculation unit that calculates normal ranges of the state quantities for each of the movement relationship values ​​based on the information stored in the storage unit, and a determination unit that, after the normal ranges have been calculated, determines whether the state quantities detected by the sensor unit are within the normal ranges based on the calculation results by the calculation unit when the laser head moves relative to the workpiece to process the workpiece.

[0008] An abnormality determination method according to one aspect of the present invention is a method for determining a processing abnormality in a processing device having a moving unit that moves relative to a workpiece, and a processing unit that is provided on the moving unit and processes the workpiece while moving relative to the workpiece together with the moving unit, and includes: detecting a state quantity of the processing device by a sensor unit that moves relative to the workpiece together with the moving unit when the processing unit moves relative to the workpiece in accordance with the movement of the moving unit and processes the workpiece normally; acquiring a movement relationship value related to the movement of the moving unit by an acquisition unit; storing the state quantity detected by the sensor unit in correspondence with the movement relationship value acquired by the acquisition unit by a storage unit; calculating a normal range of the state quantity for each movement relationship value by a calculation unit based on the information stored in the storage unit; and after the normal range is calculated, determining whether the state quantity detected by the sensor unit is within the normal range based on the calculation result by the calculation unit when the processing unit processes the workpiece while moving relative to the workpiece in accordance with the movement of the moving unit.

[0009] The abnormality determination device, laser processing machine, and abnormality determination method according to the above aspects set the normal range in consideration of the movement-related value relating to the movement of the moving part, and therefore can accurately determine abnormalities in processing of the workpiece.

[0010] In the abnormality determination device of the above aspect, the movement relationship value may include the movement speed of the moving unit. With this configuration, the normal range is set taking the movement speed into consideration, so that processing abnormalities on the workpiece can be determined with high accuracy. In the abnormality determination device of the above aspect, the movement relationship value may include the movement direction of the moving unit. With this configuration, the normal range is set taking the movement direction into consideration, so that processing abnormalities on the workpiece can be determined with high accuracy. In the abnormality determination device of the above aspect, the moving unit may be a laser head provided in the laser processing machine, and the processing unit may be a laser emission unit of the laser head that emits laser light. With this configuration, processing abnormalities in laser processing of the workpiece can be determined with high accuracy in the laser processing machine.

[0011] In the abnormality determination device of the above aspect, the calculation unit may calculate a table indicating a normal range for each movement relationship value based on the information stored in the storage unit, and the determination unit may determine whether the state quantity detected by the sensor unit is within the normal range based on the table. The calculation unit may derive an arithmetic expression for calculating the normal range for each movement relationship value based on the information stored in the storage unit, and the determination unit may determine whether the state quantity detected by the sensor unit is within the normal range based on the arithmetic expression. This configuration enables accurate determination of a processing abnormality for a workpiece using the table or arithmetic expression. In the abnormality determination device of the above aspect, the sensor unit may detect at least one of the analysis results of light quantity, temperature, sound, and image as the state quantity. This configuration enables detection of a processing abnormality from at least one of the analysis results of light quantity, temperature, sound, and image. In the laser processing machine of the above aspect, the head control device may be configured to stop processing of the workpiece when the determination unit determines that the state quantity detected by the sensor unit is outside the normal range. This configuration enables automatic stopping of processing of the workpiece when a processing abnormality occurs. In addition, the laser processing machine of the above aspect may further include a head control device that, when the determining unit determines that the state quantity detected by the sensor unit is outside the normal range, changes the moving speed of the laser head until the state quantity detected by the sensor unit falls within the normal range. With this configuration, when an abnormality occurs in processing of the workpiece, the abnormality can be dealt with without stopping processing of the workpiece, and a decrease in productivity can be suppressed.

[0012] 1 is a diagram illustrating an example of a laser processing machine and an abnormality determination device according to an embodiment; FIG. 2 is a diagram illustrating an example of the configuration of a laser head; FIG. 3 is a diagram illustrating an example of the functional parts of an abnormality determination unit; FIG. 4 is a diagram illustrating a first example of a table; FIG. 5 is a diagram illustrating a first example of a table; FIG. 6 is a diagram illustrating a second example of a table; FIG. 7 is a diagram illustrating a method of dividing a speed setting range; FIG. 8 is a diagram illustrating a method of calculating a normal range of a state quantity from a normal range calculation table; FIG. 9 is a diagram illustrating a method of calculating a normal range of a state quantity from a normal range calculation table; FIG. 10 is a diagram illustrating a method of calculating a normal range of a state quantity from a normal range calculation table;

[0013] The present invention will be described below through embodiments, but the following embodiments do not limit the scope of the invention. Furthermore, not all of the combinations of features described in the embodiments are necessarily essential to the solution of the invention. In the drawings, identical or similar parts may be designated by the same reference numerals, and redundant explanations may be omitted. Furthermore, the shapes and sizes of elements in the drawings may be exaggerated for clarity, and may differ in shape, size, etc. from the actual product.

[0014] Fig. 1 is a diagram showing an example of a laser processing machine 1 and an abnormality determination device 3 according to an embodiment. Fig. 2 is a diagram showing an example of the configuration of a laser head 12 provided in the laser processing machine 1 of Fig. 1. The laser processing machine 1 according to this embodiment is an apparatus that emits laser light L to perform laser processing such as cutting and marking on a workpiece W to be processed. The laser processing machine 1 includes a processing device 2 and an abnormality determination device 3. The processing device 2 includes a laser oscillator 10, an illumination unit 11, a laser head 12, an imaging unit 13, a head driving unit 14, a head control device 15, and an assist gas supply unit 16.

[0015] The laser oscillator 10 generates a processing laser beam L1. For example, the processing laser is an infrared laser beam. The laser oscillator 10 is connected to a laser head 12 via an optical fiber F. The optical fiber F introduces the processing laser beam L1 output from the laser oscillator 10 to the laser head 12. The illumination unit 11 includes a laser array 11A and a collimator 11B. The laser array 11A emits an illumination laser beam L2 having a wavelength different from that of the processing laser beam L1. The collimator 11B is provided at a position where the illumination laser beam L2 is incident from the laser array 11A, and converts the illumination laser beam L2 incident from the laser array 11A into a parallel beam.

[0016] The laser head 12 irradiates the workpiece W with laser light L (processing laser light L1 and illumination laser light L2) from the nozzle 20. The laser head 12 is provided so as to be movable relative to the workpiece W in the X direction, Y direction, and Z direction. The laser head 12 performs cutting by irradiating the processing laser light L1 along a cutting line to be formed on the workpiece W while moving relative to the workpiece W. The laser head 12 is an example of a "moving unit."

[0017] 2, the laser head 12 includes a nozzle 20, a collimator 21, a beam splitter 22, a condenser lens 23, a half mirror 24, a wavelength selection filter 25, and an imaging lens 26. The nozzle 20 is attached to the lower side (-Z side) of the laser head 12. The nozzle 20 faces downward. The nozzle 20 has an exit hole 20A.

[0018] The processing laser beam L1 and the illumination laser beam L2 are irradiated downward from the emission hole 20A. The nozzle 20 is connected to the assist gas supply unit 16 via a gas supply pipe or the like. The nozzle 20 supplies assist gas from the assist gas supply unit 16 to the workpiece W toward the area to be irradiated with the processing laser beam L1. The nozzle 20 is an example of a processing unit and corresponds to a laser emission unit. The illumination unit 11, imaging unit 13, beam splitter 22, half mirror 24, wavelength selection filter 25, imaging lens 26, and other components may not necessarily be provided in an embodiment in which the sensor 30 detects light intensity, temperature, sound, etc. (an embodiment in which a state quantity other than the image analysis result is detected).

[0019] The collimator 21 is provided so that the focal point on the incident side of the processing laser light L1 coincides with the position of the end of the optical fiber F, and converts the processing laser light L1 output from the laser oscillator 10 into parallel light. The beam splitter 22 is provided at a position where the processing laser light L1 that has passed through the collimator 21 is incident, and the condenser lens 23, which transmits the processing laser light L1 and reflects the illumination laser light L2, is provided at a position where the processing laser light L1 from the beam splitter 22 is incident, and condenses the incident processing laser light L1. The condenser lens 23 can be moved along the optical axis by an optical system drive unit (not shown). The focus on the workpiece W side is adjusted by this optical system drive unit.

[0020] The half mirror 24 is provided at a position where the illumination laser light L2 that has passed through the collimator 11B is incident, and reflects a portion of the illumination laser light L2 and allows a portion of it to pass through. The illumination laser light L2 reflected by the half mirror 24 is reflected by the beam splitter 22. The condenser lens 23 condenses the illumination laser light L2 that has reflected by the beam splitter 22. The area on the workpiece W that is irradiated with the illumination laser light L2 is set so as to include the area on the workpiece W that is irradiated with the processing laser light L1.

[0021] The returning light from the workpiece W passes through the condenser lens 23 and enters the beam splitter 22. The returning light includes light that is the illumination laser light L2 reflected and scattered by the workpiece W, and light that is the processing laser light L1 reflected by the workpiece W. The light originating from the illumination laser light L2 is reflected by the beam splitter 22 and enters the half mirror 24. Similarly, the light originating from the processing laser light L1 is reflected by the beam splitter 22 and enters the half mirror 24. If molten metal from the workpiece W is welded to the cut surface of the workpiece W, the returning light includes light in the infrared to near-infrared wavelength band emitted from the molten metal. The light originating from the molten metal is reflected by the beam splitter 22 and enters the half mirror 24.

[0022] The wavelength selection filter 25 is, for example, a dichroic mirror, a notch filter, or the like. The returning light incident on the half mirror 24 passes through the half mirror 24 and enters the wavelength selection filter 25. The light originating from the illumination laser light L2 is reflected by the wavelength selection filter 25 and enters the imaging lens 26. On the other hand, the light originating from the processing laser light L1 passes through the wavelength selection filter 25. The imaging lens 26 focuses the light reflected by the wavelength selection filter 25 onto the imaging unit 13.

[0023] The imaging unit 13 is provided in the laser head 12. The imaging unit 13 is a device that images an area irradiated with the processing laser light L1. The imaging unit 13 includes an imaging element 13A. The imaging element 13A is an image sensor that detects return light that is generated when the illumination laser light L2 is reflected and scattered by the workpiece W, and generates image data. The imaging unit 13 transmits the image data generated by the imaging element 13A to the head control device 15.

[0024] The head driver 14 is controlled by the head control device 15 and moves the laser head 12 in each of the X, Y, and Z directions. The head driver 14 has, for example, a gantry that can move in the X direction, a slider that can move in the Y direction relative to the gantry, and an elevator that can move in the Z direction relative to the slider. Note that the head driver 14 is not limited to the above configuration and may be realized by other configurations such as a robot arm.

[0025] The head control device 15 controls the movement of the laser head 12 by controlling the head drive unit 14. For example, the head control device 15 acquires position information of the laser head 12 at a predetermined cycle and controls the movement of the laser head 12 by controlling the head drive unit 14 based on the acquired position information. The head control device 15 also calculates a movement relationship value, which is a value related to the movement of the laser head 12, based on the position information of the laser head 12. The movement relationship value is, for example, both or either one of the movement speed and movement direction of the laser head 12. The movement direction is the processing direction of the laser processing. The head control device 15 controls the head drive unit 14 so that the calculated movement relationship value becomes a preset setting value. The head control device 15 also outputs the calculated movement relationship value to the abnormality determination device 3.

[0026] The assist gas supply unit 16 is connected to the laser head 12. The assist gas supply unit 16 is a device that supplies assist gas into the nozzle 20. The assist gas is used to remove molten material in laser processing. Examples of the assist gas supply source include a gas cylinder and a factory supply line. Examples of the assist gas that can be used include nitrogen gas, air, and a mixture of nitrogen and oxygen.

[0027] The abnormality determination device 3 may have an image processing unit (not shown) that generates data related to the machining state based on image data generated by the image sensor 13A. For example, the image processing unit may generate data indicating the kerf width as the data related to the machining state, or may create numerical information indicating the combustion state, such as the behavior of the molten metal in the workpiece W, or both. The data related to the machining state may be an example of the analysis results of the above-mentioned image. The abnormality determination device 3 determines a machining abnormality of the workpiece W in the machining device 2. The abnormality determination device 3 includes a sensor 30 and an abnormality determination unit 31.

[0028] The sensor 30 is provided in the laser head 12. For example, the sensor 30 is provided integrally with the laser head 12 and configured to move in the same manner as the laser head 12 moves. The sensor 30 may also be provided inside the laser head 12. The sensor 30 moves relative to the workpiece W together with the laser head 12 as the laser head 12 moves, and detects a state quantity X related to the machining of the workpiece W by the machining device 2. The state quantity X is one or more pieces of data used by the abnormality determination unit 31 to determine whether the machining device 2 is normal or abnormal, and is a value that directly or indirectly indicates the state of the machining device 2. Here, the sensor 30 is an example of a "sensor unit" of the present invention. For example, the "sensor unit" of the present invention detects at least one of the analysis results of light intensity, temperature, sound, and image as the state quantity X.

[0029] As an example, the "sensor unit" of the present invention may have one or more of the sensors listed below. That is, the state quantity X may be a sensor value detected by one or more of the sensors listed below: (a) a temperature sensor that detects heat generation from the condenser lens 23 for converging and diffusing the laser light; (b) a light intensity sensor that detects the intensity of reflected light of the processing laser light L1; (c) a sound sensor that detects sound around the laser head 12; and (d) an image sensor that monitors the size of the cut groove and the behavior of the molten metal based on an image of the area around the processing point.

[0030] Note that if the sensor unit is the sensor exemplified in (a), (b), or (c), the sensor unit corresponds to the sensor 30. In this case, the lighting unit 11, the imaging unit 13, and the image processing unit are not essential components for implementing the present invention. On the other hand, if the sensor unit is the sensor exemplified in (d), the sensor unit corresponds to the lighting unit 11, the imaging unit 13, and the image processing unit. In this case, the sensor 30 illustrated in FIG. 1 is not essential components for implementing the present invention. If the sensor unit corresponds to the lighting unit 11, the imaging unit 13, and the image processing unit, the abnormality determination device 3 includes, for example, the lighting unit 11, the imaging unit 13, and the image processing unit as a sensor unit. Here, the image processing unit may be included in the abnormality determination unit 31, or may be a device other than the abnormality determination unit 31. The device other than the abnormality determination unit 31 may be, for example, the imaging unit 13. In the example shown below, for convenience of explanation, a case where the sensor unit is the sensor 30 will be described as an example.

[0031] The abnormality determination unit 31 is an information processing device such as a computer. The abnormality determination unit 31 is connected to the head control device 15 and is capable of sending and receiving information to and from the head control device 15. The abnormality determination unit 31 is connected to the sensor 30. The abnormality determination unit 31 determines a machining abnormality of the workpiece W in the machining device 2 based on the state quantity X detected by the sensor 30.

[0032] 3 is a diagram illustrating an example of functional units of the abnormality determination unit 31. As illustrated in FIG. 3, the abnormality determination unit 31 includes an acquisition unit 40, a storage unit 41, a calculation unit 42, a determination unit 43, and an output unit 44. These components are implemented by, for example, a hardware processor such as a CPU (Central Processing Unit) executing a program (software). Furthermore, some or all of these components may be implemented by hardware (including circuitry) such as an LSI (Large Scale Integrated circuit), an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a GPU (Graphics Processing Unit), or may be implemented by a combination of software and hardware.

[0033] The program may be stored in advance in a storage device (a storage device with a non-transitory storage medium) such as a hard disk drive (HDD) or flash memory, or may be stored in a removable storage medium (a non-transitory storage medium) such as a DVD or CD-ROM, and installed in the storage device by inserting the storage medium into a drive device. The storage device may be configured, for example, with a HDD, flash memory, EEPROM (Electrically Erasable Programmable Read Only Memory), ROM (Read Only Memory), RAM (Random Access Memory), or the like.

[0034] The acquisition unit 40 acquires movement-related values ​​related to the movement of the laser head 12. For example, the acquisition unit 40 acquires the movement-related values ​​from the head control device 15. The acquisition unit 40 may have a communication interface for communicating with the head control device 15, for example.

[0035] When normal laser processing (hereinafter referred to as "test processing") is performed on the workpiece W by irradiating laser light from the nozzle while the laser head 12 is moving, the storage unit 41 stores the state quantity X detected by the sensor 30 in association with the movement relationship value acquired by the acquisition unit 40. In other words, during the test processing, the storage unit 41 stores the state quantity X detected by the sensor 30 in association with the movement relationship value acquired by the acquisition unit 40 at regular intervals. Note that when the "sensor unit" of the present invention is the sensor (d) above, the abnormality determination unit 31 may further include the above-mentioned image processing unit as a functional unit. In this case, the storage unit 41 acquires the image analysis result from the image processing unit as the state quantity X.

[0036] Test machining is laser machining of a test workpiece W (hereinafter referred to as "test workpiece") in a state where no machining abnormalities occur. For example, the machining conditions for the test machining are adjusted in advance so that laser machining can be performed without causing excessive burning or a decrease in the quality of the machined product due to poor cutting. In this test machining, the operator determines whether normal laser machining is being performed on the workpiece W in consideration of the actual workpiece machining state, machining properties, etc. In this form, test data, which is information in which the state quantity X and the movement relationship value during normal laser machining are associated, is stored in the storage unit 41. Note that the state quantity X detected by the sensor 30 during test machining may be referred to as the "state quantity X1" to distinguish it from other state quantities.

[0037] The calculation unit 42 calculates a normal range of the state quantity X (hereinafter referred to as the "normal range") for each movement relationship value based on test data stored in the storage unit, which is information correlating the state quantity X with the movement relationship value during normal laser processing. For example, the calculation unit 42 creates a table 100 that directly or indirectly defines the normal range of the state quantity X for each movement relationship value based on the test data stored in the storage unit 41. Note that the calculation unit 42 may create the table 100 for each workpiece W (such as the material and thickness of the workpiece W), or may create the table 100 for each processing condition for processing the workpiece W, or may do both. The processing conditions are, for example, the output of the processing laser beam L1, the focal position of the processing laser beam L1 with respect to the workpiece, and the pressure of the assist gas.

[0038] For example, the table 100 may be a table (hereinafter referred to as a "normal range table") that directly defines the normal range of the state quantity X for each moving speed and moving direction in a matrix format, and may be composed of one or more tables. FIG. 4 is a diagram showing a first example of a normal range table according to this embodiment. In FIG. 4, the maximum and minimum values ​​of the state quantity X are expressed as absolute values ​​as the normal range. The normal range table shown in FIG. 4 includes a minimum value table (FIG. 4A) and a maximum value table (FIG. 4B). The minimum value table is a table in which the minimum values ​​of the normal range of the state quantity X are defined in a matrix format for each setting range of the moving speed (hereinafter referred to as the "speed setting range") and each setting range of the moving direction (hereinafter referred to as the "direction setting range"). The maximum value table is a table in which the maximum values ​​of the normal range of the state quantity X are defined in a matrix format for each setting range of the speed setting range and each setting range of the direction setting range.

[0039] FIG. 5 is a diagram showing a second example of the table 100. The table 100 may be a table indirectly defining the normal range of the state quantity X for each moving speed and moving direction in a matrix form. For example, as shown in FIG. 5, the table 100 may be a table (hereinafter referred to as a "normal range calculation table") defining information (e.g., statistical information) for calculating the normal range of the state quantity X for each moving speed and moving direction in a matrix form, and may be composed of one or more tables. In the normal range calculation table shown in FIG. 5, the average value, standard deviation, and number of samples are used as the statistical information. More specifically, the normal range calculation table shown in FIG. 5 includes an average value table ( FIG. 5A ), a standard deviation table ( FIG. 5B ), and a number of samples table ( FIG. 5C ).

[0040] The mean value table is a table in which the mean value of the state quantity X1 is defined in a matrix for each speed setting range and direction setting range. The standard deviation table is a table in which the standard deviation of the state quantity X1 is defined in a matrix for each speed setting range and direction setting range. The sample number table is a table in which the number of samples of the state quantity X1 is defined in a matrix for each speed setting range and direction setting range. The number of samples of the state quantity X1 is the number of state quantities X1 used to create the mean value table or standard deviation table. Note that the statistical information for calculating the normal range is not limited to the mean value, standard deviation, and number of samples, and may include other statistical information such as kurtosis and skewness.

[0041] 6A and 6B are diagrams showing a method for dividing the speed setting range. The widths of the speed setting ranges may all be the same, or may not all be the same. For example, the widths may be set exponentially so that the width of the speed setting range becomes wider as the speed increases. That is, when dividing the normal range table into a matrix for each moving speed and moving direction, the division may be performed by linearly dividing the normal range table into equal parts as shown in FIG. 6A, or the speed setting range may be divided exponentially so that the width becomes wider as the speed increases as shown in FIG. 6B.

[0042] The method of linearly dividing the speed setting range equally has a simple configuration and is useful when it is necessary to reliably link the normal range to the moving speed when the speed is stable, such as at low speeds. The method of exponentially dividing the speed setting range makes it possible to stabilize the criteria for determining abnormalities because the parameters referenced in the table are less likely to change even when the moving speed changes significantly in the high-speed range. In other words, the method of exponentially dividing the speed setting range is useful when the moving speed changes significantly in the high-speed range. In the example of FIG. 6(B), the same table parameters are referenced for the speed setting range of 21 to 33 m / min. On the other hand, in FIG. 6(A), three table parameters must be referenced for the speed setting range of 21 to 33 m / min.

[0043] When the laser head 12 moves to perform actual laser processing (hereinafter referred to as "actual processing") on a workpiece W that is not for testing, the determination unit 43 determines whether or not there is an abnormality in the state quantity X detected by the sensor 30, that is, whether or not the state quantity X is within a normal range, based on the table 100, which is an example of the calculation result of the calculation unit 42. The actual processing is performed after the table 100 is calculated.

[0044] For example, during actual machining, the determination unit 43 periodically acquires the state quantity X detected by the sensor 30 and the movement-related value of the laser head 12. The state quantity X during actual machining may be referred to as the "state quantity X2." The determination unit 43 acquires the normal range associated with the movement-related value during actual machining from the normal range table. Then, the determination unit 43 periodically determines whether the state quantity X2 is within the read normal range. If the state quantity X2 is outside the normal range, the determination unit 43 determines that a machining abnormality has occurred. For example, if the state quantity X2 has fallen outside the normal range even once, the determination unit 43 determines that a machining abnormality has occurred.

[0045] However, without being limited to this form, the determination unit 43 may determine that a machining abnormality has occurred if the number of times that the state quantity X2 has fallen outside the normal range during the most recent predetermined period exceeds a specified number of times (an integer equal to or greater than 1). The number of times that it has been determined that an abnormality has occurred may be the number of times that the state quantity X has fallen out of the normal range consecutively during the most recent predetermined period. The specified number of times may be changeable depending on the workpiece W to be machined and the machining conditions.

[0046] When the normal range calculation table is used to determine whether or not there is an abnormality, the calculation unit 42 periodically acquires the state quantity X2 detected by the sensor 30 and the movement relationship value during actual machining. Then, the calculation unit 42 acquires the average value and standard deviation associated with the movement relationship value during actual machining, and creates a normal range based on the acquired average value and standard deviation.

[0047] 7A and 7B are diagrams illustrating a method for determining the normal range of the state quantity X from the normal range calculation table. As shown in FIG. 7A, the calculation unit 42 may calculate the range between the upper limit value shown in formula (1) and the lower limit value shown in formula (2) as the normal range based on the average value and standard deviation obtained from the normal range calculation table. However, the calculation unit 42 is not limited to this form, and may calculate the range below the upper limit value shown in formula (1) as the normal range (FIG. 7B), or may calculate the range above the lower limit value shown in formula (2) as the normal range (FIG. 7C). The determination unit 43 determines whether the state quantity X2 is within the normal range using a method similar to the abnormality determination described above.

[0048] Upper limit = average value + α1 × standard deviation (1) Lower limit = average value - α2 × standard deviation (2)

[0049] The gains α1 and α2 may be the same value or different values. In the example shown in Fig. 7, both α1 and α2 are set to "3". Note that α1 and α2 may be set based on the kurtosis and skewness.

[0050] Here, when the number of samples associated with the movement-related values ​​during actual machining acquired in a certain cycle is extremely small, the judgment unit 43 may not perform an abnormality judgment of the state quantity X2 in that cycle, or may perform a gain adjustment process, such as increasing the values ​​of the gain α1 and the gain α2 from “3” to “4” in the abnormality judgment in that cycle.

[0051] The output unit 44 outputs the determination result of the determination unit 43. For example, the output unit 44 may output the determination result only when the determination unit 43 determines that a processing abnormality exists. For example, the output unit 44 may output the determination result of the determination unit 43 to a display device (not shown) to display the determination result of the determination unit 43 on the display device. However, this is not limited to this configuration, and the output unit 44 may output the determination result of the determination unit 43 to a communication terminal used by a user via a wired or wireless communication network. Furthermore, the determination result of the determination unit 43 may be used for feedback control of processing conditions (such as reducing the movement speed). For example, when the determination unit 43 determines that a processing abnormality exists, the output unit 44 may output a signal indicating the determination result to the head control device 15. When the head control device 15 receives the signal indicating the determination result of the determination unit 43, the head control device 15 may perform feedback control to change the movement speed until the movement speed falls within a normal range.

[0052] The flow of the abnormality determination method according to this embodiment will be described below. Fig. 8 is a flow diagram of the abnormality determination method according to this embodiment. The laser processing machine 1 first starts test processing (step S101). During the test processing, the abnormality determination device 3 stores the state quantity X detected by the sensor 30 in association with the movement-related value of the laser head 12 (step S102). Based on the information stored in the storage unit, the abnormality determination device 3 calculates the normal range of the state quantity X for each movement-related value (step S103).

[0053] In the test machining, the laser processing machine 1 laser processes a test workpiece into a predetermined shape (hereinafter referred to as the "test machining shape"). The test machining shape is a shape that ensures a sufficient number of samples for the movement speeds and movement directions that frequently occur in shapes machined in actual machining. FIG. 9 shows a first example of the test machining shape. For example, as shown in FIG. 9, the laser processing machine 1 laser processes a first shape as the test machining shape, which is a plurality of nested regular dodecagons, while moving the laser head. The laser processing machine 1 may change the maximum speed of the laser head 12 for each regular dodecagon. The first shape can generate an equal number of samples of the state quantity X in each movement direction every 30°.

[0054] FIG. 10 shows a second example of a test machining shape. For example, as shown in FIG. 10 , the laser processing machine 1 moves the laser head to laser-machine a second shape, which is a test machining shape consisting of multiple nested squares. For example, the laser processing machine 1 changes the maximum speed of the laser head 12 for each square to round the corners of the squares. When the test machining shape is limited to a rectangle, the second shape allows for the accumulation of a larger number of data points for the state quantity X1 when the movement direction is 0°, 90°, 180°, and 270°. Furthermore, since the second shape rounds the corners of the squares, it is possible to accumulate state quantities X1 for movement directions other than 0°, 90°, 180°, and 270°.

[0055] The processes from step S101 to step S103 are performed before actual machining. After these processes are completed, actual machining is performed (step S104). After the processes from step S101 to step S103 are performed once, actual machining, as described below, may be performed for a certain period (possibly several months or more) without performing steps S101 to S103 again, as long as the machining target (the material and shape of the workpiece) remains unchanged. After actual machining is performed, the abnormality determination device 3 determines whether or not a machining abnormality exists (step S105). For example, the abnormality determination device 3 acquires a movement-related value and a state quantity X2 during actual machining. The abnormality determination device 3 then selects a normal range associated with the acquired movement-related value from the normal ranges for each movement-related value calculated in step S103. The abnormality determination device 3 then determines whether or not the state quantity X2 falls within the selected normal range. If the state quantity X2 falls within the normal range, the abnormality determination device 3 determines that no machining abnormality exists. For example, if the state quantity X2 falls outside the normal range once or multiple times, the abnormality determination device 3 determines that a machining abnormality has occurred.

[0056] If it is determined in step S105 that no machining abnormality has occurred, the abnormality determination device 3 determines whether or not actual machining has been completed (step S106). If actual machining has not been completed, the abnormality determination device 3 proceeds to step S105 again.

[0057] If the determination unit 43 determines in step S105 that a machining abnormality exists, the output unit 44 outputs the determination result to, for example, a display device (step S107). In this manner, the output unit 44 notifies the user of the machining abnormality. If the output unit 44 determines that no machining abnormality exists, the output unit 44 may or may not output the determination result. If the abnormality determination device 3 determines that a machining abnormality exists in step S105, the abnormality determination device 3 may communicate with the head control device 15 to stop actual machining. For example, if the abnormality determination device 3 determines that a machining abnormality exists in step S105, the abnormality determination device 3 transmits a machining abnormality signal indicating this to the head control device 15. The head control device 15 may stop machining of the workpiece when it receives the machining abnormality signal. However, this is not limited to this. Instead of stopping workpiece machining when it receives the machining abnormality signal, the head control device 15 may perform feedback control, such as slowing down the movement speed during actual machining. As an example, when the head control device 15 receives a processing abnormality signal, it may change the movement speed of the laser head 12 until the state quantity X detected by a sensor unit such as the sensor 30 falls within the normal range. In other words, when the determination unit 43 determines that the state quantity X detected by the sensor unit is outside the normal range, the head control device 15 may change the movement speed of the laser head 12 until the state quantity X detected by the sensor unit falls within the normal range. With this configuration, when a processing abnormality occurs on the workpiece W, the laser processing machine 1 can deal with the processing abnormality without stopping the processing of the workpiece W.

[0058] The effects of this embodiment will be described below. Fig. 11 is a diagram showing the problems with abnormality determination in a laser processing machine according to a comparative example. Fig. 12 is a diagram showing the relationship between the state quantities obtained in normal laser processing and the movement speed and movement direction. Fig. 11(A) shows the state quantities obtained in normal laser processing, and Figs. 11(B) and 11(C) show the movement speed and movement direction of the laser head at that time.

[0059] The inventors of the present application have found that, as shown in Figures 11 and 12, the possible values ​​of the state quantity X under normal conditions may differ depending on movement-related values ​​such as the moving speed and moving direction of the laser head 12. Possible factors for this include differences in the way heat is transferred, the influence of the amount of heat already stored in the workpiece, the shape and misalignment of the laser beam, and the directivity of the sensor 30 itself. Conventional abnormality determinations do not take into account differences in the state quantity X due to movement-related values ​​such as the moving speed and moving direction of the laser head 12. Furthermore, in order to minimize the occurrence of "false judgments" in which a machining abnormality is erroneously determined when machining is normal, a wide range 200 shown in Figure 11(A) is sometimes set as the normal range.

[0060] Here, range 200 is a fixed range regardless of the movement relationship value. Therefore, a portion of range 210 within range 200 may be outside the range of state quantity X obtained by normal laser processing, and if state quantity X is within range 210, it is possible that a processing abnormality has occurred. In such a case, if the normal range is set to range 200 as described above, it may be possible that the occurrence of a processing abnormality cannot be detected even if there is a processing abnormality. The abnormality determination device 3 of this embodiment sets a range that takes into account the movement relationship value, i.e., a range 300 that varies depending on the movement relationship value, as the normal range. With this configuration, it is possible to determine a processing abnormality when state quantity X is detected within range 210, and it becomes possible to accurately determine a processing abnormality for the workpiece W.

[0061] In the above embodiment, the state quantity X detected by a sensor unit such as the sensor 30 is directly transmitted to the abnormality determination device 3. However, this is not limiting, and the state quantity X detected by the sensor unit may be transmitted to the head control device 15. In this case, the state quantity X is transmitted from the head control device 15 to the abnormality determination device 3.

[0062] In the above embodiment, the abnormality determination device 3 acquires the movement relationship value from the head control device 15. However, without being limited to this configuration, the abnormality determination device 3 (e.g., the acquisition unit 40) may acquire position information of the laser head 12 from the head control device 15 or the laser head 12 and calculate the movement relationship value based on the acquired position information of the laser head 12. Furthermore, the abnormality determination device 3 may combine acquiring the movement relationship value from the head control device 15 and calculating the movement relationship value based on the position information of the laser head 12. In this case, the acquisition unit 40 of the abnormality determination device 3 may use either the movement relationship value acquired from the head control device 15 or the movement relationship value calculated by itself, or may newly calculate the average of both values ​​as the movement relationship value.

[0063] In the above embodiment, an example has been described in which the normal range of the state quantity X for each movement relationship value is set as the table 100. However, the present invention is not limited to this example, and the calculation unit 42 may calculate the normal range of the state quantity X for each movement relationship value as an arithmetic expression based on the information stored in the storage unit 41. When the normal range is expressed as an arithmetic expression, for example, the following expressions (3) to (5) are possible.

[0064] Xmin≦X≦Xmax…(3) Xmax(v,θ)=a ０ V ２ +a １ V+a ２ +b ０ sin(b １ θ+b ２ )...(4) Xmin(v,θ)=c ０ V ２ +c １ V+c ２ +d ０ sin(d １ θ+d ２ ) … (5)

[0065] Xmin is the maximum value of the state quantity X among the normal values, and Xmax is the minimum value of the state quantity X among the normal values. v is the moving speed of the laser head 12, and θ is the moving direction of the laser head 12. ｎ ,b ｎ ,c ｎ ,d ｎ(n is 1 to 3) is a constant, which may be set for each type of machining object, machining condition, and state quantity X.

[0066] In the above embodiment, the calculation unit 42 calculates the range between the upper limit value shown in Equation (1) and the lower limit value shown in Equation (2) as the normal range based on the average value and standard deviation obtained from the normal range calculation table. However, this is not a limitation. For example, the calculation unit 42 may calculate the range between the upper limit value shown in Equation (6) and the lower limit value shown in Equation (7) as the normal range based on the average value obtained from the normal range calculation table. However, this is not a limitation. The calculation unit 42 may calculate the range below the upper limit value shown in Equation (6) as the normal range, or the range above the lower limit value shown in Equation (7) as the normal range. Note that the fixed values ​​shown below may be set in advance and based on information stored in the storage unit 41.

[0067] Upper limit value = average value + fixed value (6) Lower limit value = average value - fixed value (7)

[0068] In the above embodiment, the determination unit 43 may take the rate of change of the state quantity X into consideration when determining an abnormality, and may determine that a machining abnormality has occurred if the rate of change of the state quantity X2 deviates from a reference value. For example, assuming that the state quantity X2 is acquired at a constant period T, the state quantity X2 at time t is represented as X(t). Here, the rate of change of the state quantity X2 is either or both of the rate of change ΔX(t) of the state quantity X2 per unit time and the rate of change Δ'X(t) of the state quantity X per moving distance. The rate of change ΔX(t) is expressed by the following equation (8). The rate of change Δ'X(t) is expressed by the following equation (9).

[0069] ΔX(t)=(X(t)-ΔX(t-T)) / T...(8) ΔX'(t)=(X(t)-ΔX(t-T)) / (v(t)・T)...(9)

[0070] The determination unit 43 may calculate the rate of change ΔX(t) during actual machining, and determine that a machining abnormality has occurred when this rate of change ΔX(t) exceeds an upper limit value. The determination unit 43 may determine that a machining abnormality has occurred when the rate of change ΔX(t) falls below a lower limit value. The determination unit 43 may determine that a machining abnormality has occurred when the rate of change ΔX(t) falls outside the range between the upper limit value and the lower limit value.

[0071] The determination unit 43 may also calculate the rate of change Δ′X(t) during actual machining, and determine that a machining abnormality has occurred when this rate of change Δ′X(t) exceeds an upper limit value. The determination unit 43 may also determine that a machining abnormality has occurred when the rate of change Δ′X(t) falls below a lower limit value. The determination unit 43 may also determine that a machining abnormality has occurred when the rate of change Δ′X(t) falls outside the range between the upper limit value and the lower limit value.

[0072] Here, when an abnormality is determined using the rate of change of the state quantity X, the upper and lower limit values ​​of the rate of change of the state quantity X may be calculated based on the information accumulated in the accumulation unit 41. In other words, the calculation unit 42 may calculate the upper and lower limit values ​​of the rate of change of the state quantity X for each movement relationship value as a normal range of the state quantity X based on the information accumulated in the accumulation unit 41. In this case, the upper and lower limit values ​​of the rate of change of the state quantity X may be set in a table or may be set using an arithmetic expression. Furthermore, the upper and lower limit values ​​of the rate of change may be changeable depending on the workpiece W to be machined and the machining conditions.

[0073] In the abnormality determination of the above embodiment, a transfer function G may be provided that can take into account the continuity of deviations of the state quantity from the normal range. FIG. 13 is a diagram showing the transfer function G according to this embodiment. The determination unit 43 may treat the determination of normality or abnormality as a continuous quantity, for example, from 0 to 1, and determine the presence or absence of a machining abnormality using a transfer function G such as a first-order lag. For example, the determination unit 43 inputs a value indicating whether the state quantity X2 is normal or abnormal at a fixed period into the transfer function G such as a first-order lag, with normality being "0" and abnormality being "1." The determination unit 43 then determines a machining abnormality only when the value output from the transfer function G exceeds a threshold value S. This configuration makes it possible to detect only abnormalities that have continued for a long period of time. The threshold value S may be variable depending on the workpiece W to be machined and the machining conditions.

[0074] In the above embodiment, when the state quantity X includes multiple sensor values, the calculation unit 42 may calculate the normal range (e.g., table 100, arithmetic expression, etc.) of the state quantity X for each movement-related value for each sensor value. In this case, the determination unit 43 may perform an abnormality determination for each sensor value individually. The determination unit 43 may determine a machining abnormality when detecting that even one of the determination results for each sensor value deviates from the normal range, i.e., an abnormal sensor value. However, this is not limited to this form. For example, an upper limit on the number of items for which abnormal sensor values ​​are tolerated may be set, and when abnormal sensor values ​​exceeding this number are detected, the determination unit 43 may determine a machining abnormality. Furthermore, the determination unit 43 may weight the abnormality determination for each sensor value and generate a combined score. Then, the determination unit 43 may determine a machining abnormality when the score exceeds a predetermined value. Note that the predetermined value may be changeable depending on the workpiece W to be machined and the machining conditions.

[0075] In the above embodiment, when the state quantity X includes a plurality of sensor values, the determination unit 43 may correlate the behaviors of the plurality of sensor values ​​to generate a state quantity X3 that is a new determination index, and perform an abnormality determination on the generated state quantity X3. In this case, the calculation unit 42 calculates the normal range of the state quantity X3 for each movement relationship value using the above-mentioned method, such as the table 100 and the arithmetic expressions exemplified in equations (3) to (5).

[0076] In the above embodiment, an example has been described in which the abnormality determination device 3 is applied to the laser processing machine 1. However, the device to which the abnormality determination device 3 is applied is not limited to the laser processing machine 1, and the abnormality determination device 3 can be applied to a plotter that draws pictures using NC (Numerical Control), a skiving machine that performs skiving, a machining center, or the like.

[0077] <Additional Notes> The above embodiments disclose at least the following configurations: (Configuration 1) An abnormality determination device for determining abnormalities in processing of a workpiece in a processing device having a moving unit that moves relative to a workpiece, and a processing unit that is provided on the moving unit and processes the workpiece while moving together with the moving unit relative to the workpiece, the abnormality determination device comprising: a sensor unit that detects a state quantity related to processing of the workpiece by the processing device, an acquisition unit that acquires movement relationship values ​​related to the movement of the moving unit, a storage unit that stores the state quantities detected by the sensor unit in association with the movement relationship values ​​acquired by the acquisition unit when the processing unit normally processes the workpiece while moving relative to the workpiece in accordance with the movement of the moving unit, a calculation unit that calculates a normal range of the state quantities for each of the movement relationship values ​​based on information accumulated in the storage unit, and a determination unit that, after the normal ranges have been calculated, determines whether the state quantities detected by the sensor unit are within the normal ranges based on a calculation result by the calculation unit when the processing unit processes the workpiece while moving relative to the workpiece in accordance with the movement of the moving unit. (Configuration 2) The abnormality determination device according to Configuration 1, wherein the movement relationship value includes a movement speed of the moving unit. (Configuration 3) The abnormality determination device according to Configuration 1 or 2, wherein the movement relationship value includes a movement direction of the moving unit. (Configuration 4) The abnormality determination device according to any of Configurations 1 to 3, wherein the moving unit is a laser head provided in the laser processing machine, and the processing unit is a laser emission unit of the laser head that emits laser light. (Configuration 5) The abnormality determination device according to any of Configurations 1 to 4, wherein the calculation unit calculates a table indicating the normal range for each of the movement relationship values ​​based on information accumulated in the accumulation unit, and the determination unit determines whether the state quantity detected by the sensor unit is within the normal range based on the table.(Configuration 6) An abnormality determination device according to any one of configurations 1 to 5, wherein the calculation unit derives an arithmetic expression for calculating the normal range for each of the movement-related values ​​based on the information stored in the storage unit, and the determination unit determines whether the state quantity detected by the sensor unit is within the normal range based on the arithmetic expression. (Configuration 7) An abnormality determination device according to any one of configurations 1 to 6, wherein the sensor unit detects at least one of light quantity, temperature, sound, and image analysis results as the state quantity. (Configuration 8) A laser processing machine comprising: a laser head that moves relative to a workpiece; a laser emission unit that is provided on the laser head and moves together with the laser head relative to the workpiece while emitting laser light to the workpiece to process the workpiece; and the abnormality determination device according to any one of configurations 1 to 7. (Configuration 9) A laser processing machine according to configuration 8, further comprising a head control device that stops processing of the workpiece when the determination unit determines that the state quantity detected by the sensor unit is outside the normal range. (Configuration 10) The laser processing machine according to Configuration 8, further comprising a head control device that, when the determination unit determines that the state quantity detected by the sensor unit is outside the normal range, changes the moving speed of the laser head until the state quantity detected by the sensor unit falls within the normal range.

[0078] Although the embodiments have been described above, the technical scope of the present invention is not limited to the above-described embodiments. Furthermore, it will be apparent to those skilled in the art that various modifications and improvements can be made to the above-described embodiments. It is clear from the claims that such modifications and improvements can also be included within the technical scope of the present invention. Furthermore, one or more of the requirements described in the above-described embodiments may be omitted. Furthermore, the requirements described in the above-described embodiments may be combined as appropriate. Furthermore, the execution order of each procedure shown in the embodiments can be realized in any order as long as the results of a previous procedure are not used in a subsequent procedure. Furthermore, even if the operations in the above-described embodiments are described using terms such as "first," "next," and "continuously" for convenience, this order is not required. Furthermore, to the extent permitted by law, the disclosures of Japanese Patent Application No. 2022-113303 and all documents cited in the above-described embodiments are incorporated herein by reference.

[0079] DESCRIPTION OF SYMBOLS 1... Laser processing machine 2... Processing device 3... Abnormality determination device 12... Laser head 30... Sensor 31... Abnormality determination unit 40... Acquisition unit 41... Storage unit 42... Calculation unit 43... Determination unit 44... Output unit

Claims

1. An abnormality determination device for determining a machining abnormality of a workpiece in a machining apparatus having a moving part that moves relative to a workpiece and a processing part that is provided on the moving part and moves together with the moving part relative to the workpiece while processing the workpiece, a sensor unit provided on the moving part, the sensor unit moving together with the moving part relative to the workpiece to detect a state quantity related to the processing of the workpiece by the processing device; an acquisition unit that acquires a movement relationship value related to the movement of the moving unit; a storage unit that stores the state quantity detected by the sensor unit in association with the movement relationship value acquired by the acquisition unit when the processing unit moves relative to the workpiece in accordance with the movement of the moving unit and performs normal processing on the workpiece; a calculation unit that calculates a normal range of the state quantity for each of the movement relationship values ​​based on the information stored in the storage unit; an abnormality determination device comprising: a determination unit that, after the normal range is calculated, determines whether or not the state quantity detected by the sensor unit is within the normal range based on a calculation result by the calculation unit when the processing unit moves relative to the workpiece in conjunction with the movement of the moving unit and processes the workpiece.

2. The abnormality determination device according to claim 1 , wherein the movement relationship value includes a movement speed of the moving part.

3. The abnormality determination device according to claim 1 , wherein the movement relationship value includes a movement direction of the moving part.

4. The moving unit is a laser head provided in a laser processing machine, The abnormality determination device according to claim 1 , wherein the processing unit is a laser emission unit of the laser head that emits laser light.

5. The calculation unit calculates a table indicating the normal range for each of the movement relationship values ​​based on the information stored in the storage unit, The abnormality determining device according to claim 1 , wherein the determining unit determines whether the state quantity detected by the sensor unit is within the normal range based on the table.

6. The calculation unit derives an arithmetic expression for calculating the normal range for each of the movement relationship values ​​based on the information stored in the storage unit, 2. The abnormality determining device according to claim 1, wherein the determining unit determines whether the state quantity detected by the sensor unit is within the normal range based on the arithmetic expression.

7. The abnormality determination device according to claim 1 , wherein the sensor unit detects at least one of an amount of light, a temperature, a sound, and an analysis result of an image as the state quantity.

8. A laser processing machine including: a laser head that moves relative to a workpiece; a laser emission unit that is provided on the laser head and moves relative to the workpiece together with the laser head while emitting a laser beam to the workpiece to process the workpiece; and an abnormality determination device that determines abnormality in processing the workpiece, The abnormality determination device includes: a sensor unit provided in the laser head and moving together with the laser head relative to the workpiece to detect a state quantity of the laser processing machine; an acquisition unit that acquires a movement relationship value related to the movement of the laser head; a storage unit that stores the state quantity detected by the sensor unit in association with the movement relationship value acquired by the acquisition unit when the laser emission unit moves relative to the workpiece in accordance with the movement of the laser head and performs normal processing on the workpiece; a calculation unit that calculates a normal range of the state quantity for each of the movement relationship values ​​based on the information stored in the storage unit; a judgment unit that judges whether or not the state quantity detected by the sensor unit is within the normal range based on a calculation result by the calculation unit when the laser head moves relative to the workpiece while processing the workpiece after the normal range is calculated.

9. 9. The laser processing machine according to claim 8, further comprising a head control device that stops processing of the workpiece when the determining section determines that the state quantity detected by the sensor section is outside the normal range.

10. 9. The laser processing machine according to claim 8, further comprising a head control device that, when the judgment unit judges that the state quantity detected by the sensor unit is outside the normal range, changes a moving speed of the laser head until the state quantity detected by the sensor unit falls within the normal range.

11. A method for determining a machining abnormality of a workpiece in a machining apparatus having a moving part that moves relative to a workpiece and a machining part that is provided on the moving part and moves together with the moving part relative to the workpiece while machining the workpiece, comprising: When the processing unit moves relative to the workpiece in accordance with the movement of the moving unit and normally processes the workpiece, a state quantity of the processing device is detected by a sensor unit that moves relative to the workpiece together with the moving unit; acquiring a movement relationship value related to the movement of the moving unit by an acquiring unit; storing the state quantity detected by the sensor unit in a storage unit in association with the movement relationship value acquired by the acquisition unit; calculating a normal range of the state quantity for each of the movement relationship values ​​by a calculation unit based on the information stored in the storage unit; After the normal range is calculated, when the processing part moves relative to the workpiece in association with the movement of the moving part and processes the workpiece, determining whether the state quantity detected by the sensor part is within the normal range based on a calculation result by the calculation part.