Numerical control device

Abstract

The present invention provides a technology for a numerical control device to detect the gap amount based on the nonlinear relationship between the output voltage of a gap sensor and the gap amount, which can expand the detectable distance of the numerical control device and ensure high detection accuracy of the gap amount. The numerical control device (1) comprises: a measurement interval storage unit (12) which stores a plurality of measurement intervals of output voltages measured by a gap amount measuring unit (21) and stores a switching position for switching the measurement intervals; a measurement interval control unit (13) which switches the measurement interval of the output voltage measured by the gap amount measuring unit (21) at the switching position based on the measurement intervals and the switching position stored in the measurement interval storage unit (12); and a correlation table generation unit (14) which generates a correlation table between the output voltage and the gap amount based on the output voltage measured by the gap amount measuring unit (21) and stored in the data storage unit (11) when the measurement interval is switched at the switching position by the measurement interval control unit (13).

Description

Technical Field

[0001] The invention relates to a numerical control device. Background Art

[0002] In conventional laser processing devices, a gap sensor is used to measure the distance between the processing head and the surface of the object to be processed (called the gap amount), and laser processing is performed while maintaining a fixed gap amount. A voltage corresponding to the gap amount output from the gap sensor is input to a numerical control device, etc., which detects the gap amount.

[0003] For example, a technique has been proposed in which a numerical control device samples and stores the output voltage of a gap sensor and detects the gap amount based on the stored sampled data (for example, see Patent Document 1). In this technique, the numerical control device samples and stores the output voltage of the gap sensor at fixed intervals.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent No. 2597597 Summary of the invention

[0007] Problems to be solved by the invention

[0008] However, in the case of a gap sensor such as an electrostatic capacitance type, the relationship between the output voltage and the gap amount is not proportional. Therefore, the numerical control device detects the gap amount by linearly approximating the nonlinear relationship between the gap sensor output voltage and the gap amount.

[0009] However, in recent years, the detectable distance of the gap sensor has been expanded. On the other hand, the storage capacity of assembly software such as numerical control devices is limited, and it is difficult to increase the number of samples. Therefore, the current situation is that the detectable distance of the numerical control device cannot be expanded. For example, by increasing the measurement interval of sampling, the detectable distance of the numerical control device can be expanded, but if the measurement interval is increased, the detection accuracy is reduced and the processing accuracy is deteriorated.

[0010] Therefore, in a numerical controller that detects the gap amount based on the nonlinear relationship between the gap sensor output voltage and the gap amount, a technology that can increase the detectable distance of the numerical controller and ensure high detection accuracy of the gap amount is desired.

[0011] Means for solving problems

[0012] One embodiment of the present disclosure is a numerical control device, comprising: a data storage unit that stores an output voltage of a gap amount measuring unit corresponding to a distance from a workpiece surface, i.e., a gap amount; a correlation table generating unit that pre-generates a correlation table between the output voltage stored in the data storage unit and the gap amount; a displacement amount calculating unit that calculates a distance from a reference position set near the workpiece surface, i.e., a displacement amount, based on an output voltage newly measured by the gap amount measuring unit and the correlation table pre-generated by the correlation table generating unit; a gap control unit that controls the gap amount so that the displacement amount calculated by the displacement amount calculating unit becomes a reference displacement amount; and an axis control unit that calculates a distance from a reference position set near the workpiece surface, i.e., a displacement amount, based on an output voltage newly measured by the gap amount measuring unit and the correlation table pre-generated by the correlation table generating unit. The gap amount controlled by the gap control unit controls the driving axis of the machining head, and the numerical control device also includes: a measurement interval storage unit, which stores a plurality of measurement intervals of the output voltage measured by the gap amount measuring unit and stores a switching position for switching the measurement intervals; and a measurement interval control unit, which switches the measurement interval of the output voltage measured by the gap amount measuring unit at the switching position based on the measurement interval stored in the measurement interval storage unit and the switching position, and the correlation table generation unit generates the correlation table based on the output voltage measured by the gap amount measuring unit and stored in the data storage unit when the measurement interval is switched at the switching position by the measurement interval control unit.

[0013] Effects of the Invention

[0014] According to one embodiment of the present disclosure, in a numerical controller that detects a gap amount based on a nonlinear relationship between a gap sensor output voltage and the gap amount, the detectable distance of the numerical controller can be increased and high gap amount detection accuracy can be ensured. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a diagram showing the configuration of a numerical control device according to one embodiment of the present disclosure.

[0016] Figure 2 This is a diagram showing the detectable distance of a numerical controller when sampling is performed at a fixed short measurement interval in a conventional numerical controller.

[0017] Figure 3 This is a diagram showing the detectable distance of a numerical controller when sampling is performed at a fixed long measurement interval in a conventional numerical controller.

[0018] Figure 4 yes Figure 2 A partial enlarged view of .

[0019] Figure 5 yes Figure 3 A partial enlarged view of .

[0020] Figure 6 This is a diagram for explaining switching of measurement intervals in the numerical controller according to one embodiment of the present disclosure.

[0021] Figure 7 This is a diagram showing detectable distances in a numerical controller according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0022] Hereinafter, one embodiment of the present disclosure will be described in detail with reference to the drawings.

[0023] A numerical controller 1 of an embodiment of the present disclosure detects the distance between a processing head 2 of a laser processing device and a workpiece surface, that is, the gap amount. Specifically, the numerical controller 1 of the present embodiment detects the gap amount based on a voltage corresponding to the gap amount output from a gap sensor (not shown) provided in the processing head 2. The laser processing of the present embodiment is performed based on the detected gap amount and maintaining a fixed gap amount.

[0024] The gap amount measuring unit 21 provided in the machining head 2 obtains, for example, an output voltage of a gap sensor (not shown) attached to the front end of the machining head 2. The obtained output voltage is sent to the data storage unit 11 and the displacement amount calculating unit 15 described later.

[0025] As the gap sensor, any gap sensor that can output voltage or current may be used, for example, a capacitance gap sensor is used. The gap sensor moves together with the machining head 2 and outputs a voltage corresponding to the gap between the tip of the machining head 2 and the workpiece surface.

[0026] A laser oscillator (not shown) is connected to the processing head 2. The laser oscillator generates laser light and supplies the laser light to the processing head 2 via an optical path. The processing object, i.e., a workpiece, is processed by the laser light in the form of a beam emitted from the processing head 2. The numerical control device 1 according to the present embodiment controls a driving axis (not shown) to move the processing head 2 in the horizontal direction (X-axis and Y-axis directions) and the vertical direction (Z-axis direction) relative to the workpiece.

[0027] Figure 1 1 is a diagram showing the structure of a numerical control device 1 according to an embodiment of the present disclosure. Figure 1 As shown, the numerical control device 1 includes a data storage unit 11, a measurement interval storage unit 12, a measurement interval control unit 13, a correlation table generation unit 14, a displacement amount calculation unit 15, a gap control unit 16, and an axis control unit 17. The numerical control device 1 may be configured by, for example, a computer having a CPU, a memory, and the like.

[0028] The data storage unit 11 stores the output voltage of the gap amount measuring unit 21 corresponding to the distance from the workpiece surface, that is, the gap amount. The data storage unit 11 of this embodiment is provided in the numerical control device 1, and the storage capacity is limited in embedded software such as a numerical control device. Therefore, the data storage unit 11 can only store the output voltage of the gap amount measuring unit 21 of a limited amount of data.

[0029] More specifically, the data storage unit 11 stores a plurality of sampling data for generating a correlation table generated by a correlation table generating unit 14 described later. Specifically, the data storage unit 11 establishes a correspondence between the gap amount and the sampling data of the output voltage when the machining head 2 and the gap sensor are gradually raised from the workpiece surface, and stores the corresponding data as sampling data for generating a correlation table.

[0030] The measurement interval storage unit 12 and the measurement interval control unit 13 are characteristic configurations of the numerical control device 1 of the present embodiment that have not been seen in the past. The measurement interval storage unit 12 and the measurement interval control unit 13 will be described in detail later.

[0031] The correlation table generation unit 14 generates in advance a correlation table between the output voltage and the gap amount stored in the data storage unit 11. Specifically, the correlation table between the output voltage and the gap amount is generated in advance based on the sampling data for correlation table generation stored in the data storage unit 11. A straight line approximation is performed between each sampling data, and the obtained approximate straight line is used for the calculation of the displacement amount in the displacement amount calculation unit 15 described later.

[0032] The correlation table generation unit 14 of the present embodiment is characterized in that it generates a correlation table based on sampling data measured by switching measurement intervals by the measurement interval storage unit 12 and the measurement interval control unit 13 described in detail later. This will be described in detail later.

[0033] The displacement amount calculation unit 15 calculates the distance from the reference position set near the workpiece surface, i.e., the displacement amount, based on the output voltage newly measured by the gap amount measurement unit 21 and the correlation table pre-generated by the correlation table generation unit 14. Specifically, the displacement amount calculation unit 15 refers to the correlation table pre-generated by the correlation table generation unit 14, obtains the gap amount based on the approximate straight line obtained by linearly approximating each sampling data and the newly measured output voltage, thereby calculating the distance from the reference position set near the workpiece surface, i.e., the displacement amount.

[0034] The gap control unit 16 controls the gap amount so that the displacement amount calculated by the displacement amount calculation unit 15 becomes the reference displacement amount. In other words, the gap control unit 16 controls the gap amount so that the gap amount between the machining head 2 and the workpiece surface becomes a constant amount.

[0035] The axis control unit 17 controls the drive axis of the machining head 2 based on the gap amount controlled by the gap control unit 16. Thus, the machining head 2 is moved while maintaining a fixed gap amount to perform laser machining.

[0036] Next, the measurement interval storage unit 12 and the measurement interval control unit 13 which are characteristic structures of this embodiment will be described in detail.

[0037] Here, Figure 2 This is a diagram showing the detectable distance of a numerical control device (CNC) when sampling is performed at a fixed short measurement interval in a conventional numerical control device. Figure 3 This is a diagram showing the detectable distance of a numerical control device (CNC) when sampling is performed at a fixed, long measurement interval in a conventional numerical control device. Figure 2 and Figure 3 In FIG. 1 , the horizontal axis represents the distance from the workpiece surface, and the vertical axis represents the output voltage of the gap sensor measured by the gap amount measuring unit 21. Figure 2 and Figure 3 In the figure, the measurement interval is indicated by a dotted line, and the position closer to the workpiece surface is indicated toward the right.

[0038] like Figure 2 As shown in FIG. 1 , it can be seen that when the gap amount is measured at a fixed short measurement interval, the detectable distance of the numerical control device is short. This is because, as mentioned above, the storage capacity of the numerical control device is limited, and therefore the number of sampled data is limited. In contrast, Figure 3 As shown in FIG. 1 , it can be seen that when the gap amount is measured at a fixed long measurement interval, although Figure 2 The situation is the same as the number of sampling data, but the detectable distance of the numerical control device can be expanded.

[0039] Figure 4 yes Figure 2 A partial enlarged view of Figure 5 yes Figure 3 As described above, in the electrostatic capacitance type gap sensor used in this embodiment, the relationship between the output voltage and the gap amount is nonlinear, so a straight line approximation is performed between each sampling data, and the gap amount is detected based on the obtained approximate straight line. Therefore, it can be seen that when the difference between the original nonlinear curve and the approximate straight line becomes an error, Figure 5 The case where the measurement interval is longer is shown in Figure 4 The error is larger than that in the case where the measurement interval is shorter. Therefore, if the measurement interval is extended, the detectable distance of the numerical control device is expanded, but the detection accuracy of the gap amount is reduced. In particular, the detection accuracy of the gap amount is greatly reduced at the position where the output voltage changes greatly with respect to the distance.

[0040] Therefore, in the numerical control device 1 of the present embodiment, it is possible to expand the detectable distance of the numerical control device 1 while maintaining the detection accuracy at a position with high detection accuracy of the gap amount, that is, near the surface of the workpiece. Specifically, in the numerical control device 1 involved in the present embodiment, a structure is adopted in which the measurement interval is switched according to a predetermined switching position.

[0041] That is, the measurement interval storage unit 12 of the present embodiment stores a plurality of measurement intervals of the output voltage measured by the gap amount measuring unit 21, and stores a switching position for switching the measurement interval. Thus, the measurement interval storage unit 12 of the present embodiment is different from the conventional one in that the measurement interval is not fixed, but a plurality of measurement intervals are set, and the switching position for switching the measurement interval is stored. Specifically, as described above, a shorter measurement interval is set at a position where a high detection accuracy of the gap amount is required. On the other hand, a longer measurement interval is set at a position where a high detection accuracy of the gap amount cannot be obtained. In this case, the switching position for switching the measurement interval is set between the two positions.

[0042] Furthermore, the measurement interval control unit 13 of the present embodiment switches the measurement interval of the output voltage measured by the gap amount measuring unit 21 at the switching position based on the measurement interval and the switching position stored in the measurement interval storage unit 12. Thus, the detectable distance of the numerical control device 1 can be expanded while maintaining the detection accuracy at a position requiring high detection accuracy of the gap amount, i.e., near the workpiece surface.

[0043] In this case, the correlation table generating unit 14 switches the measurement interval at the switching position through the measurement interval control unit 13, and generates the correlation table based on the output voltage stored in the data storage unit 11 by the gap amount measuring unit 21. That is, the correlation table of the present embodiment generated in this way is generated based on the output voltage measured at a plurality of different measurement intervals.

[0044] For example, the measurement interval storage unit 12 may also determine and store a plurality of measurement intervals and switching positions based on at least one of the maximum distance from the workpiece surface in the approach direction, the reference displacement, and the measurable range of the gap measurement unit 21 recorded in the machining program. Here, the movement range of the machining head 2 and the gap sensor in the approach direction, that is, the range of the distance, is determined based on the maximum distance from the workpiece surface in the approach direction and the reference displacement recorded in the machining program. In addition, the range of the distance is determined based on the measurable range of the gap sensor of the gap measurement unit 21. Therefore, by determining the measurement interval and switching position based on at least one of the maximum distance from the workpiece surface in the approach direction, the reference displacement, and the measurable range of the gap measurement unit 21 recorded in these machining programs, a more appropriate determination and switching of the measurement interval can be performed.

[0045] Figure 6 1 is a diagram for explaining the switching of the measurement interval in the numerical control device 1 of the present embodiment. Figure 6 An example of measuring the relationship between the output voltage and the gap amount while switching the measurement interval when the correlation table is generated by the correlation table generating unit 14 is shown.

[0046] exist Figure 6 In the example shown, first, the output voltage of the gap sensor is measured when the machining head 2 is arranged at the reference point. Next, the output voltage of the gap sensor is measured when the machining head 2 is raised by a distance X1, and then the output voltage of the gap sensor is further measured when the machining head 2 is raised by a distance X1. That is, the output voltage of the gap sensor is measured at each measurement interval X1.

[0047] Next, after measuring the output voltage of the gap sensor when the machining head 2 is raised by a distance X2, the output voltage of the gap sensor is further measured when the machining head 2 is raised by a distance X2. That is, the measurement interval is switched from X1 to X2, and the output voltage of the gap sensor is measured at each measurement interval X2.

[0048] In this way, the measurement interval storage unit 12 may determine and store a plurality of measurement intervals and switching positions in such a manner that the measurement interval at a position close to the workpiece surface is smaller than the measurement interval at a position far from the workpiece surface. Thus, by measuring the output voltage at a shorter measurement interval at a processing position near the workpiece surface where high detection accuracy of the gap amount is required, a higher detection accuracy can be obtained. On the other hand, by measuring the output voltage at a longer measurement interval at a position far from the workpiece surface where high detection accuracy of the gap amount is not required, the detectable distance of the numerical control device 1 can be expanded.

[0049] The switching of the measurement interval in this embodiment will be described by taking another example. Figure 7 : is a diagram showing the detectable distance in the numerical control device 1 of this embodiment. Figure 7 In FIG. 1 , the horizontal axis represents the distance from the workpiece surface, and the vertical axis represents the output voltage of the gap sensor measured by the gap amount measuring unit 21. Figure 7 In the figure, the measurement interval is indicated by a dotted line, and the further to the right, the closer to the workpiece surface.

[0050] exist Figure 7In the example shown, first, the machining head 2 and the gap sensor are raised from the reference point, and after measuring the output voltage at 10 points with a measurement interval of 0.4 mm, the measurement interval is switched to 1.2 mm at a position 4 mm away from the reference point (measurement interval 0.4 mm×10=4 mm). Next, after measuring the output voltage at 5 points with a measurement interval of 1.2 mm, the measurement interval is switched to 2.0 mm at a position 10 mm away from the reference point (4 mm+measurement interval 1.2 mm×5=10 mm). Then, the output voltage at 5 points is measured with a measurement interval of 2.0 mm, and the measurement is ended at a position 20 mm away from the reference point (10 mm+measurement interval 2.0 mm×5=20 mm). Based on the sampling data obtained in this way, a correlation table between the output voltage and the gap amount is generated, so that the detectable distance of the numerical control device 1 can be expanded to 20 mm, and high detection accuracy of the gap amount can be ensured.

[0051] According to this embodiment, the following effects are achieved.

[0052] In the present embodiment, there are provided a measurement interval storage unit 12 that stores a plurality of measurement intervals of the output voltage measured by the gap amount measuring unit 21 and stores a switching position for switching the measurement intervals, and a measurement interval control unit 13 that switches the measurement interval of the output voltage measured by the gap amount measuring unit 21 at the switching position based on the measurement intervals and the switching position stored in the measurement interval storage unit 12. In addition, based on the output voltage measured by the gap amount measuring unit 21 and stored in the data storage unit 11 by switching the measurement interval at the switching position by the measurement interval control unit 13, a correlation table between the output voltage and the gap amount is generated by the correlation table generation unit 14.

[0053] Thus, unlike conventional numerical control devices, the gap amount measurement interval can be set to multiple intervals, so when generating a correlation table, the gap amount can be measured at a shorter measurement interval at a position requiring high detection accuracy of the gap amount, and on the other hand, the gap amount can be measured at a longer measurement interval at a position not requiring high detection accuracy. Therefore, a correlation table between the output voltage and the gap amount can be generated based on the output voltage measured and stored by switching the measurement interval at a predetermined switching position. Therefore, in the numerical control device 1 that detects the gap amount based on the nonlinear relationship between the gap sensor output voltage and the gap amount, the detectable distance of the numerical control device 1 can be expanded, and the high detection accuracy of the gap amount can be ensured.

[0054] Furthermore, the moving speed of the machining head 2 is controlled by the axis control unit 17 according to the distance from the reference point. According to this embodiment, the detectable distance of the numerical controller 1 can be expanded, thereby expanding the range in which the machining head 2 can be more appropriately controlled.

[0055] In the present embodiment, a plurality of measurement intervals and switching positions are determined and stored based on at least one of the maximum distance from the workpiece surface in the approach direction described in the machining program, the reference position, and the measurable output range of the gap amount measuring unit 21 .

[0056] Thus, more appropriate measurement intervals and switching positions can be determined and stored, so that the detectable distance of the numerical controller 1 can be more appropriately expanded, and high detection accuracy of the gap amount can be ensured.

[0057] In the present embodiment, a plurality of measurement intervals and switching positions are determined and stored so that the measurement interval at a position close to the workpiece surface is smaller than the measurement interval at a position far from the workpiece surface.

[0058] Thus, the closer the position is to the workpiece surface to be laser processed, the smaller the gap amount measurement interval can be. Therefore, the detectable distance of the numerical controller 1 can be more appropriately expanded, and high gap amount detection accuracy can be ensured.

[0059] In addition, the present disclosure is not limited to the above-described embodiments, and modifications and improvements within the scope that can achieve the purpose of the present disclosure are included in the present disclosure.

[0060] In the above embodiment, an example is shown in which a plurality of measurement intervals and switching positions are determined and stored in such a manner that the measurement interval at a position close to the workpiece surface is smaller than the measurement interval at a position far from the workpiece surface, but the present invention is not limited thereto. For example, in the case of performing hole drilling using a laser before laser processing, the laser is irradiated from a position far from the workpiece surface, so it is preferable to set the measurement interval at a position far from the workpiece surface to be shorter than that near the workpiece surface.

[0061] Description of Reference Numerals

[0062] 1 Numerical control device

[0063] 2 processing heads

[0064] 11Data Storage Unit

[0065] 12 Measurement interval storage unit

[0066] 13 Measurement interval control unit

[0067] 14 Related table generation unit

[0068] 15 Displacement calculation unit

[0069] 16 Gap control unit

[0070] 17-axis control unit

[0071] 21. Gap measurement unit.

Claims

1. A numerical control device comprising: A data storage unit that stores an output voltage of a gap amount measuring unit corresponding to a distance from a workpiece surface, that is, a gap amount; a correlation table generating unit that generates in advance a correlation table between the output voltage and the gap amount stored in the data storage unit; a displacement amount calculation unit that calculates the displacement amount, which is the distance from a reference position set near the workpiece surface, based on the output voltage newly measured by the gap amount measurement unit and the correlation table pre-generated by the correlation table generation unit; a gap control unit configured to control the gap amount so that the displacement amount calculated by the displacement amount calculation unit becomes a reference displacement amount; as well as an axis control unit that controls a drive axis of a machining head based on the gap amount controlled by the gap control unit, The numerical control device is characterized in that it further comprises: a measurement interval storage unit that stores a plurality of measurement intervals of the output voltage measured by the gap amount measuring unit and stores a switching position for switching the measurement intervals; and a measurement interval control unit that switches the measurement interval of the output voltage measured by the gap amount measuring unit at the switching position based on the measurement interval stored by the measurement interval storage unit and the switching position, The correlation table generating unit generates the correlation table based on the output voltage measured by the gap amount measuring unit and stored in the data storage unit when the measurement interval is switched at the switching position by the measurement interval control unit.

2. The numerical control device according to claim 1, characterized in that: The measurement interval storage unit determines and stores the plurality of measurement intervals and the switching positions based on at least one of a maximum distance from the workpiece surface in an approach direction described in a machining program, the reference displacement amount, and a measurable range of the gap amount measuring unit.

3. The numerical control device according to claim 1 or 2, characterized in that: The measurement interval storage unit determines and stores the plurality of measurement intervals and the switching positions such that the measurement interval at a position close to the workpiece surface is smaller than the measurement interval at a position far from the workpiece surface.

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