CN113678073A

CN113678073A - Numerical control device

Info

Publication number: CN113678073A
Application number: CN201980095002.4A
Authority: CN
Inventors: 末田崇
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2019-04-12
Filing date: 2019-04-12
Publication date: 2021-11-19
Anticipated expiration: 2039-04-12
Also published as: JP6641543B1; CN113678073B; JPWO2020208827A1; WO2020208827A1

Abstract

A numerical control device (1) that controls a machine tool (2) having a tool according to a machining program, the numerical control device (1) comprising: a correction unit (12) that calculates, based on the analysis result of the machining program (5), the correction amount of a tool position command for a rotation axis error that a machine system of the machine tool (2) has; a correction operation control unit (15) that determines invalidation of correction of the position command based on the analysis result of the machining program (5); and a movement amount determination unit (16) that moves the rotating shaft to the reference position when the correction operation control unit (15) determines that the correction of the position command is invalidated.

Description

Numerical control device

Technical Field

The present invention relates to a numerical control device for controlling a processing machine such as a machine tool.

Background

A machining machine for industrial use represented by a machine tool is required to perform high-precision and complicated machining. The machine tool is generally controlled by a numerical control device, and is driven and controlled so that the tool and the table follow a command path defined by a machining program. The machine system of the work machine to be controlled has a plurality of axes, and is controlled by the numerical control device such that the positions of the respective axes follow the command positions.

In order to realize high-precision machining, a numerical control device has a function of correcting errors by changing the movement positions of respective axes in consideration of mounting errors of a mechanical system of a machine tool, deformation of the mechanical system due to temperature change, and deflection inherent to components. If this function is used, if the machine tool has only a linear axis, the error can be corrected by moving the tool in a direction to cancel out the error at the position determined by the position where the tool is moved. However, in order to machine a complicated shape, a machine system of a machine tool in recent years has been increasingly configured to include a rotation shaft for rotating a table in addition to a linear shaft. In this case, in addition to an error in the position of the tool when the tool is linearly moved, an error in the position of the workpiece that occurs when the table is rotated occurs, and the machining accuracy deteriorates. Therefore, as a function of correcting an error with respect to the rotation axis of the table, a function of correcting an error of the rotation center is studied (for example, patent document 1).

Patent document 1: international publication No. 2011/104757

Disclosure of Invention

In the function of correcting the error of the rotation center, the error of the position of the workpiece, that is, the error of the rotation center, which is generated by the rotation of the table is calculated using the positional deviation data and the angular deviation data of the rotation axis that rotates the table of the machine tool, and the error is corrected by moving the tool so as to cancel the error. The correction is to move the tool to the correct position as the position corresponding to the workpiece on the table. However, for example, when a tool is moved to a tool replacement position of a turret having a plurality of tools for replacing the tool, since the turret is a mechanical system separate from the table, no positional error occurs due to rotation of the rotary shaft at the tool replacement position. Therefore, it is necessary to move the tool to the replacement position after the correction is invalidated. At this time, if the correction is immediately invalidated in a state where the correction amount is present, that is, in a state where the rotation axis of the table is at a position other than 0 °, the tool is moved stepwise to a position where the correction amount is not present on the rotation axis. Since correction by angular deviation of the rotation axis is performed for a plurality of linear axes, the stepped movement also occurs in multiple axes. As a result, mechanical vibration and vibration sound are generated, which may cause mechanical failure.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a numerical control device capable of suppressing mechanical vibration generated when correcting an error of a rotation center to be invalid.

In order to solve the above problems and achieve the object, the present invention provides a numerical control device for controlling a machine tool having a tool according to a machining program, the numerical control device including: a correction unit that calculates a correction amount of a tool position command relating to a rotation axis error included in a machine system of a machine tool; a correction operation control unit that determines invalidation of correction of the position command based on an analysis result of the machining program; and a movement amount determination unit that moves the rotary shaft to the reference position when the correction operation control unit determines that the correction of the position command is invalidated.

ADVANTAGEOUS EFFECTS OF INVENTION

The numerical control device according to the present invention has an effect of suppressing mechanical vibration generated when correcting an error of a rotation center to be invalid.

Drawings

Fig. 1 is a diagram showing a configuration example of a machine tool to be controlled by a numerical control device.

Fig. 2 is a diagram showing a configuration example of a table included in a machine tool to be controlled by a numerical control device.

Fig. 3 is a diagram showing an example of a function of correcting an error of a rotation center generated in a machining operation of a machine tool.

Fig. 4 is a diagram showing a configuration example of a numerical control device according to an embodiment of the present invention.

Fig. 5 is a diagram for explaining operation example 1 of a movement amount determining unit included in the numerical control device.

Fig. 6 is a diagram for explaining operation example 2 of the movement amount determining unit included in the numerical control device.

Fig. 7 is a diagram showing an example of a time constant corresponding to the 2 nd operation example shown in fig. 6.

Fig. 8 is a diagram showing an example of an operation of replacing a tool by a machine tool which is a control target of the numerical control device.

Fig. 9 is a diagram showing an example of a machining program corresponding to the operation shown in fig. 8.

Fig. 10 is a diagram showing an example of an operation of invalidating the correction by the numerical control device.

Fig. 11 is a diagram showing another example of an operation of invalidating the correction by the numerical control device.

Fig. 12 is a diagram showing an example of hardware for realizing the numerical control device.

Detailed Description

A numerical control device according to an embodiment of the present invention will be described in detail below with reference to the drawings. The present invention is not limited to the embodiments.

Provided is an implementation mode.

First, a machine tool to be controlled by a numerical control device according to the present invention will be described with reference to fig. 1 to 3. Fig. 1 is a diagram showing a configuration example of a machine tool to be controlled by a numerical control device.

The work machine shown in fig. 1 has a table 101. A workpiece 102 as an object to be processed is fixed on a table 101. The table 101 has a rotation axis parallel to the Z axis. In addition, the work machine has a column 103. A spindle head 104 is attached to the column 103, and a tool 105 is attached to the spindle head 104. The spindle head 104 has a mechanism for tilting the tool 105. A numerical control device, not shown, controls the relative position and angle of the tool 105 fixed to the main shaft head 104 with respect to the 3-dimensional space of the workpiece 102, and brings the tool 105 into contact with the workpiece 102. In this state, the numerical control device rotates a spindle motor, not shown, to rotate the tool 105, thereby cutting the workpiece 102.

The rotation axis of the tool 105 coincides with the spindle of the spindle head 104. When the Tool 105 is replaced according to the machining application, the numerical control device moves the spindle head 104 to the position of the atc (automation Tool changer) arm 106. In this state, the ATC arm 106 replaces the tool 108 for replacement attached to the turret 107 and the tool 105 attached to the spindle head 104. In the machine tool shown in fig. 1, the table 101 moves in the Y-axis direction, and the spindle head 104 moves in the X-axis direction and the Z-axis direction. The selection of whether the table 101 or the spindle head 104 is moved in each axis is appropriately determined in accordance with the purpose of the machine tool or the like at the time of machine design.

The machine tool to be controlled by the numerical control device may have a table 201 having a structure shown in fig. 2. Fig. 2 is a diagram showing a configuration example of a table included in a machine tool to be controlled by a numerical control device. The table 201 shown in fig. 2 has a tilting mechanism. When the work machine has a table 201 having a tilting mechanism as shown in fig. 2, the spindle head 104 shown in fig. 1 may not have a mechanism for tilting the tool 105. Here, the selection of whether the tilt mechanism is on the spindle head side or the table side is appropriately determined in accordance with the application of the machine tool in the machine design, similarly to the selection of which of the table 101 and the spindle head 104 is moved.

Fig. 3 is a diagram showing an example of a function of correcting an error of a rotation center generated in a machining operation of a machine tool. The error corrected by the correction function shown in fig. 3 is an error that the mechanical system of the work machine shown in fig. 1 has. The correction function shown in fig. 3 is realized by the numerical control device according to the present invention controlling the machine tool. The table 101 shown in fig. 3 is provided with a positional deviation 301 and an angular deviation 302. The positional deviation 301 is a deviation between the original position of the rotation axis 303A and the actual position of the rotation axis 303B of the table 101. The angular deviation 302 is a deviation between the original angle of the rotation axis 303A and the actual angle of the rotation axis 303B of the table 101.

The rotation center error correction amount corrects an error generated due to a positional deviation or an angular deviation when rotating from a position at which the rotation angle is 0 °. Therefore, the reference position at which the rotation center error correction value becomes 0 is set to 0 ° in the present embodiment.

When there is a positional deviation 301 and an angular deviation 302 in the table 101, the numerical control device performs a positional correction 304 and an angular correction 305 of the spindle head 104 in accordance with the rotation of the table. That is, the numerical control device controls the main shaft head 104 so that the relative position and the relative angle of the main shaft head 104 and the workpiece (not shown) fixed to the table 101 when the rotation angle of the table is 0 ° are always equal. This eliminates the influence of variations in the rotating mechanism of the machine tool, thereby improving the machining accuracy.

Next, a numerical control device according to the present embodiment will be explained. Fig. 4 is a diagram showing a configuration example of a numerical control device according to an embodiment of the present invention. In fig. 4, a device connected to the numerical control device, such as a machine tool and a Programmable Logic Controller (PLC), is also shown.

The numerical control device 1 according to the present embodiment reads a machining program 5 and controls the machine tool 2 in accordance with the contents of a command described in the machining program 5. The structure of the work machine 2 is as shown in fig. 1. In fig. 4, the drive control unit 21, the servo motor 22, and the spindle motor 23, which are directly related to the control by the numerical control device 1, are described among the components of the machine tool 2, and the description of various components such as the table 101, the column 103, the spindle head 104, and the tool 105 shown in fig. 1 is omitted.

The not-shown table 101 and spindle head 104 are driven in the respective axial directions by servo motors 22 attached to the respective axes. The rotational motion of the servo motor 22 is converted into linear motion of the table 101 or the spindle head 104 by a motion transmission element such as a ball screw. The drive control of the servo motors 22 for the respective axes is performed by the drive control unit 21.

The drive control unit 21 drives and controls a servo motor 22 attached to the rotary shaft of the table 101 to rotate the table 101.

The numerical control device 1 is connected to a display unit 3 in addition to the machine tool 2 and the PLC 4. The display unit 3 is realized by a display device such as a liquid crystal monitor or a display. The numerical control device 1 may be configured to include the display unit 3.

As shown in fig. 4, the numerical control device 1 includes a program analyzing unit 11, a correcting unit 12, a correcting operation control unit 15, and a movement amount determining unit 16. The correction unit 12 includes a correction amount calculation unit 13 and a rotation axis deviation data storage unit 14.

The program analysis unit 11 analyzes the machining program 5 read by the numerical control device 1, and determines a command to be executed. Note that the numerical control device 1 may acquire the machining program 5 in advance and store the machining program in a storage unit, which is not shown.

The correction unit 12 calculates a correction amount for performing the position correction 304 and the angle correction 305 shown in fig. 3. The correction unit 12 calculates a correction amount for each axis driven by each servo motor 22, that is, for each rotation axis. In the correction unit 12, the correction amount for each axis is calculated by the correction amount calculation unit 13. The rotation axis deviation data storage unit 14 stores the deviation data of the rotation axis, which is data used when the correction amount is calculated by the correction amount calculation unit 13. The deviation data of the rotation axis includes a deviation amount between the rotation axis center position in the mechanical design and the actual rotation axis center position (hereinafter, referred to as a positional deviation amount), and a deviation amount between the rotation axis angle in the mechanical design and the actual rotation axis angle (hereinafter, referred to as an angular deviation amount).

The correction operation control unit 15 determines whether or not to perform the position correction 304 and the angle correction 305 shown in fig. 3 based on the analysis result of the machining program 5 obtained by the program analysis unit 11. The correction operation control unit 15 outputs a switching command indicating the determination result to the movement amount determination unit 16. The detailed operation of the correction operation control unit 15 will be described later.

The movement amount determination unit 16 determines the movement amounts of the tool 105 and the table 101 based on the analysis result of the machining program 5 obtained by the program analysis unit 11, the correction amounts for the respective axes calculated by the correction unit 12, and the switching command input from the correction operation control unit 15. The movement amount determination unit 16 displays the correction amount for each axis calculated by the correction unit 12 on the display unit 3 and notifies the user of the display amount. When a switching command indicating that the position correction 304 and the angle correction 305 are not to be performed is input from the correction operation control unit 15, the movement amount determination unit 16 determines a movement amount for moving the rotation axis of the table 101 to the position of 0 °.

Next, the operation of the numerical control device 1 for controlling the work machine 2 will be described. The numerical control device 1 analyzes the machining program 5 by the program analyzing unit 11. If the program analysis unit 11 analyzes the movement command included in the machining program 5, the movement amount determination unit 16 of the numerical control device 1 determines the movement amount of the servo motor 22 for each axis based on the analysis result of the movement command, and transmits the determined movement amount to the drive control unit 21. The movement command here is a command for moving one or both of the spindle head 104 and the table 101 to which the tool 105 is attached, and is a command of G00 code, G01 code, G02 code, or the like of a general numerical control program. When determining the movement amount of the main shaft head 104, the movement amount determination unit 16 compares the position of the movement destination of the main shaft head 104 indicated by the movement command with the current position of the main shaft head 104, and determines the movement amount of the main shaft head 104 for each axis.

Similarly, when determining the movement amount of the table 101, the movement amount determination unit 16 compares the position of the movement destination of the table 101 indicated by the movement command with the current position of the table 101, and determines the movement amount of the table 101 for each axis. At this time, the movement amount determination unit 16 determines the movement amount in consideration of the correction amount of each axis input from the correction unit 12 in accordance with the instruction from the correction operation control unit 15.

Specifically, when a switching command indicating that correction is necessary is input from the correction operation control unit 15, the movement amount determination unit 16 determines the movement amount in consideration of the correction amount for each axis input from the correction unit 12. That is, the movement amount determination unit 16 corrects the movement amount determined based on the analysis result of the movement command obtained by the program analysis unit 11, using the correction amount for each axis input from the correction unit 12. Then, the movement amount determination unit 16 outputs the corrected movement amount to the drive control unit 21. The target of correction is the amount of movement of each axis for moving the main spindle head 104 to which the tool 105 is attached.

On the other hand, when a switching command indicating that no correction is necessary is input from the correction operation control unit 15, the movement amount determination unit 16 first calculates the movement amount for moving the rotation axis of the table 101 to the position of 0 ° and outputs the calculated movement amount to the drive control unit 21, and then starts outputting the movement amount determined based on the analysis result of the movement command obtained by the program analysis unit 11 to the drive control unit 21.

The correction unit 12 receives a signal (valid/invalid signal) indicating whether the correction function is valid or not from the PLC 4. When the received signal indicates that the correction function is effective, the correction amount calculation unit 13 of the correction unit 12 calculates the correction amount. Specifically, the correction amount calculation unit 13 acquires the coordinate values of the 3-dimensional space of the movement destination of the movement object and the rotation angle of the rotation axis, acquires the amount of positional deviation and the amount of angular deviation corresponding to the coordinate values of the 3-dimensional space and the rotation angle of the rotation axis from the deviation data of the rotation axis stored in the rotation axis deviation data storage unit 14, and calculates the correction amount for each axis using the acquired pieces of information. The correction amount calculation unit 13 outputs the calculated correction amount for each axis to the movement amount determination unit 16. The correction amount for each axis includes a correction amount for a position and a correction amount for an angle.

In addition, when the signal received from the PLC 4 indicates that the correction function is invalid, the correction unit 12 does not calculate the correction amount. In this case, the correction amount calculation unit 13 outputs "0" to the movement amount determination unit 16 as the correction amount for each axis. The movement amount determination unit 16 displays the correction amount for each axis acquired from the correction unit 12 on the display unit 3, and notifies the user of the correction amount for each axis.

Next, the operations of the correction operation control unit 15 and the movement amount determination unit 16 will be described in detail. As described above, the numerical control device 1 includes the correction unit 12, and the correction unit 12 corrects the shift amount output to the drive control unit 21 by the shift amount determination unit 16 using the calculated correction amount for each axis. Therefore, when the machine tool 2 machines the workpiece 102, the deviation amount of the table 101 is corrected and the tool 105 is moved, thereby realizing high-precision machining.

However, if the amount of displacement of the table 101 is corrected when the spindle head 104 is moved to the position of the ATC arm 106 (see fig. 1) in order to replace the tool 105, a problem arises. That is, since the ATC arm 106 is a mechanism separate from the table 101, if control is performed to correct the amount of deviation of the table 101 when the spindle head 104 is moved to the position of the ATC arm 106, the spindle head 104 cannot be moved to the correct position, and there is a possibility that the spindle head 104 or the tool 105 collides with the ATC arm 106. Therefore, in the control when the tool 105 is replaced, it is necessary to invalidate the correction of the deviation amount of the table 101.

However, the user may forget to insert a command to output a signal to invalidate the correction of the deviation amount of the table 101 into the ladder program of the PLC 4. Further, there is a possibility that the timing of outputting the signal for invalidating the correction to the PLC 4 is not properly specified, and mechanical vibration occurs to damage the workpiece 102. Further, there is a fear that the timing at which the correction is invalidated by the user is studied to be troublesome, and the machining time is increased by the insertion of the operation of invalidating the correction.

Therefore, the numerical control device 1 according to the present embodiment includes the correcting operation control unit 15, and the correcting operation control unit 15 determines whether the movement is for changing the tool 105 or for machining the workpiece 102 by checking the analysis result of the machining program 5, and determines whether the state requires correction of the deviation amount of the table 101.

The correcting operation control unit 15 checks the analysis result of the machining program 5 obtained by the program analysis unit 11, and determines that the correction of the deviation amount of the table 101 is not necessary when the replacement of the tool 105 is controlled. Information used by the correction operation control unit 15 in the determination will be described later.

When receiving a switching command indicating that no correction is necessary, the movement amount determination unit 16 first outputs to the drive control unit 21 a movement amount for moving the rotary shaft of the table 101 to a position of 0 °, determines the movement amount of each shaft considering the correction amount of each shaft as 0, and starts an operation of outputting to the drive control unit 21. When the correction is not necessary, the operation in the state where the correction is invalidated, that is, the operation in which the amount of correction for each axis is determined as 0 and the amount of movement for each axis is determined after the rotation axis of the table 101 is moved to the position of 0 °, the mechanical vibration generated when the correction is invalidated can be suppressed.

In the present embodiment, the angle at which the correction defined as 0 ° is invalidated is set as the reference angle. In addition, it is preferable to move the rotation axis to the position of 0 ° in an ideal case, but in the present embodiment, the rotation axis may be moved to a range of an error of the rotation angle generated when the actual machine tool is driven.

The movement amount determining unit 16, upon receiving a switching command indicating that correction is not necessary, checks whether or not the correction amount of each axis input from the correcting unit 12 is 0, that is, whether or not the correction is invalid. In addition, when the correction is not invalidated, the movement amount determination unit 16 may display a warning indicating that the correction needs to be invalidated on the display unit 3.

As for the method of moving the axis when the correction is invalidated, as shown in fig. 5, the movement amount determination unit 16 may perform a process of adding a movement amount for invalidating the correction to a movement amount (movement amount indicated by the next movement command) determined based on the analysis result of the next movement command obtained by the program analysis unit 11. The moving amounts for invalidating the correction are

arrows

501 and 502 of broken lines shown in fig. 5. The same applies to the case where the correction is made effective after the tool 105 is replaced and before the machining is started. That is, as shown in fig. 5, invalidation may be performed simultaneously with the axis movement other than the correction invalidation. Specifically, the program is analyzed in advance, and the program determined to be invalidated operates with a composite vector of a previous move command and the invalidated move. This can be expected to shorten the machining time as compared with the case where the invalidation operation is moved alone.

In the method of moving the axis when the correction is invalidated, the movement amount determination unit 16 may move the axis with a time constant as shown in fig. 6 and 7 to suppress the mechanical vibration. Fig. 6 shows the movement of the tool 105. Fig. 7 shows time constants corresponding to the movement of the tool 105 shown in fig. 6. In the example shown in fig. 6 and 7, if the time constant elapses, the tool 105 is gradually moved to the position at which the correction is invalid. That is, the movement amount determination unit 16 determines the movement amount so that the tool 105 gradually moves to the position at which the correction is invalid as time passes. In this case, the movement amount determination unit 16 does not need to output the movement amount for moving the rotary shaft of the table 101 to the position of 0 ° to the drive control unit 21 before starting the movement of the shaft shown in fig. 6.

The time constant can be determined by the user using a parameter setting function provided in the numerical control device 1.

Next, information used by the correction operation control unit 15 to determine whether or not correction of the deviation amount of the table 101 is necessary, that is, whether or not control of replacing the tool 105 is performed will be described.

When the user of the numerical control apparatus 1 replaces the tool 105 during the machining of the workpiece 102, a tool replacement command is described in the machining program 5 so that the tool 105 moves as shown in fig. 8. An example of a machining program in this case is shown in fig. 9. The tool replacement command is generally configured to be executed by calling a subroutine created in advance to control the work machine 2.

As shown in fig. 9, the tool replacement command includes a command (tool replacement position movement command) for moving the tool 105 to the tool replacement position, a command (turret rotation command) for rotating the turret 107 and selecting a tool 108 for replacement, and a command (ATC arm operation command) for operating the ATC arm 106 and replacing the tool. Therefore, when the program analysis unit 11 analyzes the tool replacement command, the corrective action control unit 15 determines to execute control for replacing the tool 105. In this case, the correction operation control unit 15 determines that the correction amount needs to be set to 0.

The corrective action control unit 15 stores in advance the coordinates of the tool change position, which is the position where the tool 105 is changed, and when the program analysis unit 11 analyzes the command for moving the tool 105 to the tool change position, it can be determined that the control for changing the tool 105 is to be executed. In this case, when the program analysis unit 11 analyzes the command for moving the tool 105 from the tool replacement position to the other position, the corrective action control unit 15 determines that the correction amount needs to be set to 0.

Next, a timing at which the correction amount is set to 0 other than the determination of whether the correction amount is necessary at the time of tool replacement will be described. In the case of a complex machining machine, it is necessary to change the deviation data of the rotating shaft used in the correction of the deviation amount of the table 101 when the combination of the axes to be machined is changed, but if the deviation data is changed, the correction amount of each linear axis is changed, and therefore, there is a possibility that vibration may occur. Therefore, the corrective action control unit 15 determines that it is not necessary to set the correction amount to 0 even when the combination of the axes to be machined is changed in addition to the replacement of the tool 105.

Thus, the user does not need to create a program for moving the rotation axis to the position of 0 °, and the machining program creation becomes easy. Next, a method of setting the correction amount of the deviation amount of the table 101 to 0 when the combination of the axes to be machined is changed will be described.

Fig. 10 is a diagram showing an example of an operation of invalidating the correction by the numerical control device 1. Fig. 10 illustrates a mode in which it is determined that the rotation axis is set to 0 ° in addition to switching of the tool change and the shaft combination. When the program analysis unit 11 analyzes the movement command that does not involve machining, the corrective action control unit 15 transmits a switching command indicating that no correction is necessary to the movement amount determination unit 16. The positioning command, i.e., the G00 code is a movement command not accompanied by machining. Since the machine tool 2 does not machine the workpiece 102 when the positioning command is executed, it is not necessary to correct the deviation amount of the table 101. When the program analysis unit 11 analyzes the cutting command, the correction operation control unit 15 transmits a switching command indicating that correction is necessary to the movement amount determination unit 16.

The cutting commands herein include G01 code, G02 code, and G03 code. The correcting operation control unit 15 operates as described above, and thereby the correction of the deviation amount of the table 101 is always invalidated at the time of non-cutting, that is, when the tool 105 is moved without performing machining. Since the timing of changing the combination of the shafts to be machined is not the time of cutting, no mechanical vibration occurs even if the deviation data of the rotation shaft is changed. Therefore, the user can change the shaft configuration without considering the validity and invalidity of the correction function. In addition, a command for moving the rotary shaft to the position of 0 ° before the change is not required. The tool moving method when the validity or invalidity of the correction function is switched can be any of the methods shown in fig. 5 and 6.

Fig. 11 is a diagram showing another example of the operation of invalidating the correction by the numerical control device 1, that is, a method of determining that the machining is not performed except for the command. In the example shown in fig. 11, a machining area 601 in a 3-dimensional space is set in the machine tool 2, and the validity and invalidity of the correction function are switched. The machining region 601 is a region in which the machine tool 2 machines the workpiece 102, and is set to a fixed range including the position of the workpiece 102. The corrective action control unit 15 analyzes the movement command by the program analysis unit 11, and transmits a switching command indicating that no correction is necessary to the movement amount determination unit 16 when the tool movement destination indicated by the analysis result of the movement command is outside the machining region 601.

Further, when the tool movement destination indicated by the analysis result of the movement command obtained by the program analysis unit 11 is in the machining region 601, the corrective action control unit 15 transmits a switching command indicating that correction is necessary to the movement amount determination unit 16. Even when the correction operation control unit 15 operates as described above, the same effect as that in the case of performing the operation shown in fig. 10 can be obtained. The numerical control device 1 performs control of retracting the tool from the workpiece 102 at a timing at which the combination of axes to be machined is changed so as not to affect machining. Therefore, even in the case of performing the operation shown in fig. 11, the user can change the shaft configuration without considering the validity and invalidity of the correction function. In addition, a command for moving the rotary shaft to the position of 0 ° before the change is not required.

Next, a configuration of hardware for realizing the numerical control device 1 will be described. Fig. 12 is a diagram showing a configuration example of hardware for realizing the numerical control device 1.

The numerical control device 1 is realized by, for example, a processor 91, a memory 92, and an interface circuit 93 shown in fig. 12.

The processor 91 is a CPU (also referred to as a Central Processing Unit, arithmetic Unit, microprocessor, microcomputer, processor, DSP), system lsi (large Scale integration), or the like. The Memory 92 is a nonvolatile or volatile semiconductor Memory such as a ram (random Access Memory), a rom (Read Only Memory), a flash Memory, an eprom (Erasable Programmable Read Only Memory), an EEPROM (registered trademark) (Electrically Erasable Programmable Read-Only Memory), or the like. The interface circuit 93 is a circuit for transmitting and receiving various data to and from other devices.

The program analyzing unit 11, the correcting unit 12, the correcting operation control unit 15, and the movement amount determining unit 16 of the numerical control device 1 are realized by the processor 91 and the memory 92. Specifically, the above-described respective units of the numerical control device 1 are realized by storing programs for operating as the program analyzing unit 11, the correcting unit 12, the correcting operation control unit 15, and the movement amount determining unit 16 in the memory 92, and reading and executing the programs stored in the memory 92 by the processor 91.

The program analysis unit 11 also acquires the machining program 5 via the interface circuit 93. The machine tool 2, the display unit 3, and the PLC 4 are connected to the numerical control device 1 via an interface circuit 93.

As described above, the numerical control device according to the present embodiment determines whether or not correction of an error of a machine system of a machine tool to be controlled is necessary based on the analysis result of the machining program, and performs correction when correction is necessary. Specifically, the numerical control device corrects the tool movement for machining a workpiece requiring correction of the rotation axis error, and invalidates the correction after moving the position of the rotation axis of a table or the like that fixes the workpiece to 0 ° in the tool movement requiring invalidation of the correction of the rotation axis error at the time of replacement of the tool or the like. Thus, even when the user forgets to insert a command for avoiding collision between the tool and the ATC arm at the time of tool replacement into the machining program, the calibration function can be automatically stopped to avoid collision between the tool and the ATC arm.

Therefore, the numerical control device improves the reliability of the operation of correcting the error of the machine system of the machine tool. Further, since it is not necessary to insert a command for avoiding collision between the tool and the ATC arm at the time of tool replacement into the machining program in advance, the workload at the time of creating the machining program by the user can be reduced.

Conventionally, if correction is immediately invalidated with a correction amount, the tool is moved stepwise to a position where no correction amount is present, and therefore mechanical vibration occurs in multiple axes, which may cause vibration noise, mechanical failure, and the like. In addition, in the case of a mechanical structure having a tilt mechanism on the table side, since the tilt rotation shaft is also moved, there is a concern that vibration may be increased due to an increase in the amount of movement. Further, regarding the timing at which the correction is invalidated, in a case where there is a configuration in which a plurality of tables for rotating a workpiece by a complex machining machine are present other than at the time of tool replacement, for example, when the combination of axes to be machined is changed, it is necessary to switch the positional deviation data and the angular deviation data of the rotating shaft, and in this case, the correction needs to be invalidated so as not to cause vibration.

According to the numerical control device of the present embodiment, it is possible to solve the problems that have occurred in the past without creating complicated commands by a machining program or a ladder program, and to improve the reliability of operations when error correction is not necessary, such as when a tool is replaced.

The numerical control device 1 may have a configuration in which the function of the corrective operation control unit 15 described above is provided by the movement amount determination unit 16. In this case, the movement amount determination unit 16 determines whether or not the correction using the correction amount of each axis calculated by the correction unit 12 is necessary based on the analysis result of the machining program 5, and performs the correction if it is determined that the correction is necessary.

The configuration described in the above embodiment is an example of the content of the present invention, and may be combined with other known techniques, and a part of the configuration may be omitted or modified without departing from the scope of the present invention.

Description of the reference numerals

1 a numerical control device, 2 a machine tool, 3a display unit, 4 a programmable logic controller, 5 a machining program, 11 a program analysis unit, 12 a correction unit, 13 a correction amount calculation unit, 14 a rotation axis deviation data storage unit, 15 a correction operation control unit, 16 a movement amount determination unit, 21 a drive control unit, 22 a servo motor, 23 a spindle motor, 101, 201 a table, 102 a workpiece, 103 a column, 104 a spindle head, 105 a tool, 106 an ATC arm, 107 a turret, 108 a tool for replacement.

Claims

1. A numerical control device controls a machine tool having a tool based on a machining program,

the numerical control device is characterized by comprising:

a correction unit that calculates a correction amount of the position command of the tool relating to a rotation axis error included in a machine system of the machine tool;

a correction operation control unit that determines invalidation of correction of the position command based on an analysis result of the machining program; and

and a movement amount determination unit that moves the rotary shaft to a reference position when the correction operation control unit determines that the correction of the position command is invalidated.

2. A numerical control device controls a machine tool having a tool based on a machining program,

the numerical control device is characterized by comprising:

and a movement amount determination unit that moves the tool to a position where the correction amount becomes zero so as to have a time constant when the correction operation control unit determines that the correction of the position command is invalidated.

3. The numerical control apparatus according to claim 1 or 2,

the correction operation control unit determines to invalidate the correction when the analysis result shows movement of the tool for changing the tool to another tool.

4. The numerical control apparatus according to any one of claims 1 to 3,

the correction operation control unit determines to invalidate the correction when the analysis result shows the movement of the tool for changing the combination of the axes of the workpiece to be machined.

5. The numerical control apparatus according to any one of claims 1 to 4,

the correction operation control unit determines to invalidate the correction when the analysis result is an analysis result of a movement command that does not accompany the machining of the workpiece.

6. The numerical control apparatus according to any one of claims 1 to 4,

the correction operation control unit determines to invalidate the correction when the analysis result shows that the tool moves outside a certain range including a position of the workpiece.