Numerical control device and measurement position correction method

Abstract

The numerical control device has a measurement start determination unit 401 that determines when measurement has started, an axis movement direction determination unit 402 that determines the axis movement direction from internal information of the numerical control device, an axis movement amount calculation unit 403 that calculates the axis movement amount from the position determined to be the measurement start position by the measurement start determination unit 401, a measurement direction determination unit 404 that determines the measurement direction based on the axis movement direction when the axis movement amount exceeds a predetermined threshold, and a measurement position calculation unit 405 that corrects the measurement position based on the measurement direction determined by the measurement direction determination unit 404.

Description

[Technical Field]

[0001] The present disclosure relates to a numerical control device for manually measuring workpiece coordinates and a method for correcting a measurement position in manual measurement. [Background technology]

[0002] Conventionally, the position of a workpiece is measured using a measuring device attached to the spindle of a machine tool. For example, in manual mode, an operator can measure the position of the workpiece by contacting the probe with the workpiece. In this case, the operator must correct the coordinates indicating the contact position in the positive or negative direction by the amount of the probe's outer diameter, depending on the probe's approach direction to the workpiece.

[0003] For example, if the contactor approaches the workpiece in the positive direction, the outer diameter of the contactor is added to the coordinates indicating the contact position. On the other hand, if the contactor approaches the workpiece in the negative direction, the outer diameter of the contactor is subtracted from the coordinates indicating the contact position. By performing this correction, the accurate position of the workpiece can be determined. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2023 / 228356 Summary of the Invention [Problem to be solved by the invention]

[0005] However, for example, when the contactor is moved toward the workpiece in the positive direction, the operator may determine that the contactor has been moved too far and move the contactor away from the workpiece (i.e., in the negative direction). The device may detect this movement in the negative direction and subtract the amount of the contactor's outer diameter instead of adding it. This creates the problem of not being able to determine the accurate position of the workpiece.

[0006] The object of the present disclosure is to provide a device that can correctly detect the approach direction and correctly correct the contact position even when the operator determines that the contact has been "fed too far" and moves the contactor away from the workpiece. [Means for solving the problem]

[0007] One aspect of the present disclosure is a numerical control device characterized by having a measurement start determination unit that determines that measurement has started, an axis movement direction determination unit that determines the axis movement direction from internal information of the numerical control device, an axis movement amount calculation unit that calculates the axis movement amount from the position determined by the measurement start determination unit to be the measurement start position, a measurement direction determination unit that determines the measurement direction based on the axis movement direction when the axis movement amount exceeds a predetermined threshold, and a measurement position calculation unit that corrects the measurement position based on the measurement direction determined by the measurement direction determination unit. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram illustrating an industrial machine incorporating a numerical control device according to an embodiment. [Figure 2] FIG. 10 is a diagram for explaining a method for calculating a measurement position. [Figure 3] FIG. 2 is a diagram illustrating a first example of the operation of the numerical control device according to the embodiment. [Figure 4] FIG. 10 is a diagram illustrating a second example of the operation of the numerical control device according to the embodiment. [Figure 5] 1 is a functional block diagram of a numerical control device according to an embodiment; [Figure 6]10A to 10C are diagrams illustrating the operation of each unit in the first operation example. [Figure 7] 10A and 10B are diagrams illustrating the operation of each unit in the second operation example. [Figure 8] FIG. 10 is a diagram illustrating an example of calculating a movement direction from a change in machine coordinates. DETAILED DESCRIPTION OF THE INVENTION

[0009] 1 is a diagram showing an industrial machine 1 incorporating a numerical control device 2 according to an embodiment. The industrial machine 1 includes the numerical control device 2, an input / output device 3, a servo amplifier 4, a servo motor 5, a spindle amplifier 6, a spindle motor 7, and auxiliary equipment 8.

[0010] The numerical control device 2 is a control device that controls the entire industrial machine 1. The numerical control device 2 includes a hardware processor 201, a bus 202, a ROM (Read Only Memory) 203, a RAM (Random Access Memory) 204, and a non-volatile memory 205.

[0011] The hardware processor 201 is a processor that controls the entire numerical control device 2 in accordance with a system program. The hardware processor 201 reads the system program stored in the ROM 203 via the bus 202 and performs various processes based on the system program. The hardware processor 201 also controls, for example, the servo motor 5 and the spindle motor 7 based on an operation program that operates the industrial machine 1. The hardware processor 201 is, for example, a CPU (Central Processing Unit) or an electronic circuit.

[0012] The hardware processor 201, for example, analyzes the machining program and outputs control commands to the servo motor 5 and the spindle motor 7 for each control period. The ROM 203 is a storage device that stores a system program for controlling the entire numerical control device 2. The ROM 203 is a computer-readable storage medium. The RAM 204 is a storage device that temporarily stores various data and functions as a work area when the hardware processor 201 processes various data.

[0013] The nonvolatile memory 205 is a storage device that retains data even when the power to the industrial machine 1 is turned off and power is not supplied to the numerical control device 2. The nonvolatile memory 205 stores, for example, an operation program and various parameters. The nonvolatile memory 205 is a computer-readable storage medium. The nonvolatile memory 205 is, for example, a battery-backed memory or an SSD (Solid State Drive).

[0014] The numerical control device 2 further includes an interface 206 , an axis control circuit 207 , a spindle control circuit 208 , a PLC (Programmable Logic Controller) 209 , and an I / O unit 210 . The interface 206 connects the bus 202 to the input / output device 3 . The axis control circuit 207 is a circuit that controls the servo motor 5. The axis control circuit 207 receives control commands from the hardware processor 201 and sends various commands to the servo amplifier 4 for driving the servo motor 5. The axis control circuit 207 sends, for example, a torque command for controlling the torque of the servo motor 5 to the servo amplifier 4.

[0015] The servo motor 5 is driven by receiving a current supply from the servo amplifier 4. The servo motor 5 is provided on each control axis of the industrial machine 1. The spindle control circuit 208 is a circuit that controls the spindle motor 7. The spindle control circuit 208 receives a control command from the hardware processor 201 and sends a command to the spindle amplifier 6 to drive the spindle motor 7. The spindle control circuit 208 sends, for example, a spindle speed command to the spindle amplifier 6 to control the rotation speed of the spindle motor 7. The spindle motor 7 is driven by receiving a current supplied from the spindle amplifier 6. The spindle motor 7 is connected to the main shaft and rotates the main shaft.

[0016] Next, we will explain the method of calculating the measurement position executed in the numerical control device 2. The measurement position is the position of the measurement point on the object to be measured, that is, the position on the object to be measured that is in contact with the contact body.

[0017] When measuring the position of an object to be measured in manual measurement, the operator brings a contact body into contact with the object to be measured. Manual measurement means that the operator manually measures the position of the object to be measured when the numerical control device 2 is set to manual mode. "Manual" means that the operator moves the contact body using, for example, a pulse handle connected to the numerical control device 2. Alternatively, the operator moves the contact body using an axis movement switch on the operation panel.

[0018] The contact body is a member that comes into contact with the object to be measured. The contact body is, for example, a touch probe. Alternatively, the contact body may be a tool such as an end mill.

[0019] The measurement object is an object to be measured in manual measurement. The measurement object is, for example, a workpiece. The measurement object may be a table on which the workpiece is placed, or a jig for fixing the workpiece to the table.

[0020] When measuring an object to be measured using a contact body, a deviation occurs between the position of the contact body when it comes into contact with the object to be measured and the measurement position of the object to be measured that is in contact with the contact body, due to the size of the contact body. Therefore, it is necessary to calculate the measurement position by correcting information indicating the position of the contact body when it comes into contact with the object to be measured using information indicating the size of the contact body. Note that the position of the contact body when it comes into contact with the object to be measured is a reference position in measuring the object to be measured and is referred to as the "mechanical position." In contrast, the "measurement position of the object to be measured that is in contact with the contact body" is sometimes simply referred to as the "measurement position."

[0021] The machine position is the position of the control axis in the machine coordinate system. If the industrial machine 1 is a machining center, the machine position is, for example, the position of the end face of the spindle, which is the position of the central axis of the spindle.

[0022] FIG. 2 is a diagram for explaining a method for calculating a measurement position. 2, the mechanical position Pma in the X-axis direction is located in the negative direction by the radius d of the contact body T from the measurement position Pme where the contact body T is in contact with the measurement object W. Therefore, in manual measurement, the numerical control device 2 calculates the measurement position Pme as the position obtained by moving the mechanical position Pma in the positive direction by the radius of the contact body T. The state shown in FIG. 2 occurs when the contact body T is moved closer to the stationary measurement object W in the positive direction.

[0023] On the other hand, when the contact body T is moved closer to the stationary object W to be measured in the negative direction, the positional relationship between the mechanical position Pma and the measurement position Pme is reversed, so the numerical control device 2 calculates the position obtained by moving the mechanical position Pma in the negative direction by the radius of the contact body T as the measurement position Pme.

[0024] FIG. 3 is a diagram illustrating a first operation example of the numerical control device 2 according to the embodiment. Fig. 3A shows that the measuring device is moved in the +X direction to contact the workpiece. In Fig. 3B, which shows the state in which the measuring device is in contact with the workpiece, the machine position is located in the -X direction by the radius of the measuring device from the measurement position, so the measurement position is calculated as the machine position + the radius of the measuring device.

[0025] FIG. 4 is a diagram illustrating a second operation example of the numerical control device 2 according to the embodiment. (1) in Figure 4A shows the operation of moving the measuring device in the +X direction to contact the workpiece. After performing the operation (1), the operator decides that "it was fed too far," and makes a fine adjustment in (2) by moving it slightly in the -X direction.

[0026] At this time, the numerical control device 2 of the present disclosure compares the movement amount of (2) with a predetermined threshold value, and only if the movement amount is greater than the predetermined threshold value, determines the correction direction for the shape of the measuring instrument based on the movement direction of the measuring instrument, i.e., the axial movement direction, and performs correction for the shape of the measuring instrument in the determined direction.

[0027] If the comparison result shows that the amount of movement is equal to or less than a predetermined threshold, the correction direction determined during the previous movement is maintained, and correction is made in accordance with the shape of the measuring instrument in the maintained correction direction. In the case of (2), since the movement amount is below a predetermined threshold, the correction direction in (1), i.e., the positive direction, is maintained, and the measurement position is calculated by adding the radius of the measuring device to the machine position. This allows for accurate correction without being affected by fine adjustments. Figure 4B shows the result of this fine adjustment and slight movement in the -X direction. Because the measurement device has been finely adjusted and moved slightly in the -X direction, it appears to be slightly away from the workpiece. As mentioned above, the correction direction (positive direction) determined during the previous movement is maintained, so the measurement position is located in the positive direction of the machine position.

[0028] FIG. 5 is a functional block diagram of the numerical control device 2 according to the embodiment. The numerical control device 2 includes a measurement start determination unit 401, an axis movement direction determination unit 402, an axis movement amount calculation unit 403, a measurement direction determination unit 404, and a measurement position calculation unit 405. The measurement start determination unit 401, the axis movement direction determination unit 402, the axis movement amount calculation unit 403, the measurement direction determination unit 404, and the measurement position calculation unit 405 are realized, for example, by the hardware processor 201 performing arithmetic processing using a system program stored in the ROM 203, an operating program stored in the nonvolatile memory 205, and various data.

[0029] The measurement start determination unit 401 determines that measurement has started. Specifically, it determines that measurement has started based on, for example, one or more of an operator's operation, signal information, and a change in the axis movement direction.

[0030] The axis movement direction determination unit 402 determines the axis movement direction from information inside the numerical control device 2. Specifically, for example, the axis movement direction is determined based on an axis movement direction signal or a change in machine coordinates.

[0031] The axial movement amount calculation unit 403 calculates the amount of axial movement from the position determined by the measurement start determination unit 401 to be the measurement start position.

[0032] When the amount of axial movement exceeds a predetermined threshold, the measurement direction determination unit 404 determines the measurement direction based on the axial movement direction. Specifically, for example, when the amount of axial movement exceeds a predetermined threshold, the measurement direction is set to the same as the axial movement direction. When the amount of axial movement does not exceed the predetermined threshold, the axial movement direction determination unit 402 maintains the previously determined measurement direction.

[0033] The measurement position calculation unit 405 corrects the measurement position based on the measurement direction determined by the measurement direction determination unit 404. Specifically, for example, if the measurement direction is a plus direction, the measurement position is calculated by adding the radius of the measuring instrument to the machine coordinates. If the measurement direction is a minus direction, the measurement position is calculated by subtracting the radius of the measuring instrument from the machine coordinates.

[0034] The threshold value referred to by the measurement direction determination unit 404 may be held inside the numerical control device 2. Alternatively, it may be specified from outside the numerical control device 2.

[0035] FIG. 6 is a diagram illustrating the operation of each unit in the first operation example. In operation example 1, the tool is moved 10 mm in the positive X direction and brought into contact with the workpiece. In this case, the measurement start determination unit 401 determines that measurement has started due to an operator's screen operation or a signal change. Furthermore, the axis movement direction determination unit 402 determines that the axis movement direction is the positive direction based on the value of the axis movement direction signal being "0." The axis movement amount calculation unit 403 calculates the axis movement amount when measurement starts. The axis movement amount calculation unit 403 notifies the calculated axis movement amount to the measurement direction determination unit 404. The measurement direction determination unit 404 compares the axis movement amount with a predetermined threshold. Here, the predetermined threshold is assumed to be "0.1 mm." Since the axis movement amount (10 mm) exceeds the threshold (0.1 mm), the measurement direction is determined to be the "positive direction," the same as the axis movement direction. Since the measurement direction is the "positive direction," the measurement position calculation unit 405 calculates the measurement position using the formula: measurement position = machine position + tool radius.

[0036] FIG. 7 is a diagram illustrating the operation of each unit in the second operation example. In operation example 2, after operation example 1, the operator determines that "the feed was too long," and moves the tool 0.02 mm away from the workpiece for fine adjustment. The measurement start determination unit 401 determines that measurement has started because the axis movement direction has changed. The axis movement direction determination unit 402 determines that the axis movement direction is the negative direction based on the change in the value of the axis movement direction signal from "0" to "1." The axis movement amount calculation unit 403 calculates the axis movement amount when measurement starts. The axis movement amount calculation unit 403 notifies the measurement direction determination unit 404 of the calculated axis movement amount. The measurement direction determination unit 404 compares the axis movement amount with a predetermined threshold. Since the axis movement amount (0.02 mm) does not exceed the threshold (0.1 mm), the measurement direction (positive direction) determined in operation example 1 is maintained. Since the measurement direction is "positive direction," the measurement position calculation unit 405 calculates the measurement position using the formula: measurement position = machine position + tool radius.

[0037] FIG. 8 is a diagram showing an example in which the axis movement direction determination unit 402 calculates the movement direction from a change in machine coordinates. The difference is calculated based on the coordinate values, and if the difference is positive, it is determined that the axial movement direction is a plus direction, and if the difference is negative, it is determined that the axial movement direction is a minus direction.

[0038] The effect of at least one of the embodiments described above is that even if the measuring device is moved slightly away from the workpiece, i.e., even if a tool that has been fed too far is moved back slightly, the measurement direction will not be reversed as long as the amount of axial movement is below a predetermined threshold, the measurement position will not be corrected in the opposite direction by the radius of the measuring device, and the correct measurement position will be set.

[0039] Although the present disclosure has been described in detail, the present disclosure is not limited to the individual embodiments described above. Various additions, substitutions, modifications, partial deletions, etc. are possible in these embodiments without departing from the gist of the present disclosure or the spirit of the present disclosure derived from the content of the claims and their equivalents. These embodiments can also be implemented in combination. For example, in the above-described embodiments, the order of each operation and the order of each process are shown as examples and are not limited to these. The same applies when numerical values ​​or mathematical expressions are used in the description of the above-described embodiments.

[0040] The following additional notes are further disclosed regarding the above embodiment. (Appendix 1) The numerical control device (2) has a measurement start determination unit (401) that determines that measurement has started, an axis movement direction determination unit (402) that determines the axis movement direction from internal information of the numerical control device (2), an axis movement amount calculation unit (403) that calculates the axis movement amount from the position determined by the measurement start determination unit (401) to be the measurement start position, a measurement direction determination unit (404) that determines the measurement direction based on the axis movement direction when the axis movement amount exceeds a predetermined threshold, and a measurement position calculation unit (405) that corrects the measurement position based on the measurement direction determined by the measurement direction determination unit (404). (Appendix 2) In the numerical control device (2) of Supplementary Note 1, the measurement start determining unit (401) determines that measurement has started based on one or more of an operator's operation, signal information, and a change in the axis movement direction. (Appendix 3) In the numerical control device (2) of Supplementary Note 1, the axis movement direction determination unit (402) determines the axis movement direction based on an axis movement direction signal or a change in machine coordinates. (Appendix 4) In the numerical control device (2) of Supplementary Note 1, the predetermined threshold value is held inside the numerical control device (2) or is specified from outside the numerical control device (2). (Appendix 5) The measurement position correction method includes a step (401) of determining that measurement has started, a step (402) of determining the axis movement direction from internal information of the numerical control device (2), a step (403) of calculating the axis movement amount from the position determined to be the measurement start position, a step (404) of determining the measurement direction based on the axis movement direction when the axis movement amount exceeds a predetermined threshold, and a step (405) of correcting the measurement position based on the measurement direction. [Explanation of symbols]

[0041] 1. Industrial machinery 2. Numerical control device 401 Measurement start decision unit 402 Axis movement direction judgment unit 403 Axis movement amount calculation section 404 Measurement direction determination unit 405 Measurement position calculation unit

Claims

1. a measurement start determination unit that determines when measurement has started; an axis movement direction determination unit that determines an axis movement direction based on information inside the numerical control device; an axial movement amount calculation unit that calculates an axial movement amount from the position determined by the measurement start determination unit to be the measurement start position; a measurement direction determination unit that determines a measurement direction based on the axial movement direction when the axial movement amount exceeds a predetermined threshold, and maintains the previous measurement direction when the axial movement amount does not exceed the predetermined threshold; a measurement position calculation unit that corrects the measurement position based on the measurement direction determined by the measurement direction determination unit; and The measurement start determining unit determines that measurement has started based on one or more of an operator's operation, signal information, and a change in the axis movement direction.

2. The numerical control device according to claim 1 , wherein the axis movement direction determination unit determines the axis movement direction based on an axis movement direction signal or a change in machine coordinates.

3. The numerical control device according to claim 1 , wherein the predetermined threshold value is held inside the numerical control device or is specified from outside the numerical control device.

4. a step of determining an axis movement direction based on information inside the numerical control device; a step of determining that measurement has started based on one or more of an operator's operation, signal information, and a change in the axis movement direction; calculating an axial movement amount from the position determined to be the measurement start position; determining a measurement direction based on the axial movement direction when the axial movement amount exceeds a predetermined threshold, and maintaining the previous measurement direction when the axial movement amount does not exceed the predetermined threshold; correcting the measurement position based on the measurement direction; A measurement position correction method comprising:

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