Shaft operation completion determination device and shaft operation completion determination method

Abstract

Accurate prediction of machining time can be performed without using actual machining data. A machining time prediction device for a machine tool that machines a workpiece by controlling at least one axis on the basis of a machining program, the machining time prediction device comprising: an analysis unit that analyzes the machining program and generates an operation command for the axis; an execution control unit having an interpolation unit that collectively executes the operation command and instructs the operation of the shaft on the basis of the result of analyzing the machining program, and an operation completion determination unit that determines that the operation of the shaft is completed; a shaft control unit that generates a control command in accordance with an operation instruction of the shaft; a machining time prediction unit that measures a time required for execution of the machining program and predicts a machining time; and a shaft operation simulation unit that simulates the operation of the shaft on the basis of the control command and outputs a virtual actual performance, and an operation completion determination unit determines the completion of the operation of the shaft on the basis of the virtual actual performance.

Description

[0001] This application is a divisional application of the patent application with the application number 202280091041.9 and the invention title "Processing Time Prediction Device and Processing Time Prediction Method", which was filed on February 18, 2022. Technical Field

[0002] The present invention relates to a processing time prediction device and a processing time prediction method for a machine tool, and more particularly to a processing time prediction device and a processing time prediction method for predicting the processing time of a machine tool that controls at least one axis to process a workpiece according to a machining program. Background Art

[0003] In order to perform machining efficiently, it is necessary to know the time required for each process before machining. In particular, it is important to know the time required to execute the machining program of a CNC machine tool.

[0004] A numerical control device that obtains the shortest predicted machining time within an allowable machining error is described in Patent Document 1.

[0005] Specifically, Patent Document 1 describes the following: speed data for specifying the machining speed when machining a workpiece and precision data for specifying the machining precision are specified, a program analysis unit creates interpolation data for a machining program, an interpolation unit interpolates according to the speed created by a pre-interpolation acceleration / deceleration unit in accordance with the interpolation data and creates interpolation data (ΔPn), and a post-interpolation acceleration / deceleration unit performs post-interpolation acceleration / deceleration on the interpolation data (ΔPn) to create servo position command data (VCn). Further, Patent Document 1 describes the following: a servo simulation unit receives the servo position command data (VCn) and creates servo position data (Qn) that simulates the actual servo operation, a machining time prediction unit can measure the machining time by using the interpolation data or counting the number of interpolations, and a machining error prediction unit uses the interpolation data (ΔPn) and the servo position data (Qn) to obtain the predicted machining error.

[0006] A numerical control device that can perform high-precision prediction of machining time considering mechanical delays generated in a machine is described in Patent Document 2.

[0007] Specifically, Patent Document 2 discloses a numerical control device having: a reference machining time prediction unit that predicts, based on a machining program, a machining time without considering the acceleration and deceleration of axes, i.e., a reference machining time; an acceleration / deceleration number prediction unit that predicts, based on the machining program, the number of times of acceleration and deceleration of axes during machining; a data storage unit that stores information related to a deviation time, which is the difference between the actual machining time taken for the actual machining of the machine and the reference machining time predicted for this machining; a correction time calculation unit that calculates, based on the number of times of acceleration and deceleration predicted by the acceleration / deceleration number prediction unit and the information related to the deviation time stored in the data storage unit, a correction time for correcting the reference machining time; and a machining time prediction unit that calculates a predicted machining time obtained by correcting the reference machining time with the correction time.

[0008] Patent Document 3 discloses a machining time calculation device that can accurately calculate the machining time required before machining.

[0009] Specifically, Patent Document 3 discloses the following: a segmented trajectory calculation unit segments a specified tool trajectory at larger intervals for portions with small curvatures, and as the curvature of the specified tool trajectory increases, obtains a segmented trajectory segmented at smaller intervals; an axis control data calculation unit obtains, as axis control data A, the position at an arbitrary point on each segmented trajectory when machining a workpiece by moving a tool at a speed according to the specified tool movement speed on each segmented trajectory, and the time variation of the tool movement speed in each axis direction obtained at a specified time interval. Further, Patent Document 3 discloses that a machining time calculation unit calculates the machining time required for machining a specified range.

[0010] Prior Art Documents

[0011] Patent Documents

[0012] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2012-243152

[0013] Patent Document 2: Japanese Unexamined Patent Application Publication No. 2017-207823

[0014] Patent Document 3: Japanese Unexamined Patent Application Publication No. 2009-098981 Summary of the Invention

[0015] Problems to be Solved by the Invention

[0016] When stop commands for axes frequently appear in a machining program of a CNC machine tool, and when an axis with large inertia (large response time constant) is installed in the machine tool, it is difficult to accurately predict the machining time.

[0017] In addition, if actual machining data is used for predicting the machining time, it takes time and labor to collect the data.

[0018] Therefore, it is desirable to provide a machining time prediction device for a machine tool that can accurately predict the machining time without using actual machining data, even when stop commands for the axes frequently appear in the machining program and when the machine tool is equipped with axes having large inertia.

[0019] Means for Solving the Problem

[0020] A representative first aspect of the present disclosure is a machining time prediction device that predicts the machining time of a machine tool that controls at least one axis to machine a workpiece based on a machining program.

[0021] The machining time prediction device includes:

[0022] An analysis unit that analyzes the machining program and generates motion commands for the axes;

[0023] An execution control unit that includes an interpolation unit that summarizes the execution of the motion commands and indicates the motion of the axes according to the result of analyzing the machining program, and a motion completion determination unit that determines the completion of the motion of the axes;

[0024] An axis control unit that generates control commands based on the motion instructions for the axes from the interpolation unit;

[0025] A machining time prediction unit that measures the time required for the execution of the machining program and predicts the machining time;

[0026] An axis motion simulation unit that simulates the motion of the axes based on the control commands and outputs virtual actual results,

[0027] The motion completion determination unit determines the completion of the motion of the axes based on the virtual actual results.

[0028] A representative second aspect of the present disclosure is a machining time prediction method. As a machining time prediction device that predicts the machining time of a machine tool that controls at least one axis to machine a workpiece based on a machining program, a computer executes the following processes:

[0029] A process of analyzing the machining program to generate motion commands for the axes;

[0030] A process of summarizing the execution of the motion commands, indicating the motion of the axes according to the result of analyzing the machining program, and determining the completion of the motion of the axes;

[0031] A process of generating control commands based on the motion instructions for the axes;

[0032] A process of measuring the time required for the execution of the machining program to predict the machining time;

[0033] Axis motion simulation processing that simulates the motion of the axis according to the control instruction and outputs virtual actual motion

[0034] In the process of judging the completion of the axis motion, judge the completion of the axis motion according to the virtual actual

[0035] Advantages of the Invention

[0036] According to each aspect of the present disclosure, without using actual machining data, accurate prediction of machining time can be performed even when stop commands of the axis frequently appear in the machining program and when an axis with large inertia is mounted on the machine tool. Brief Description of the Drawings

[0037] Figure 1 It is a block diagram showing the structure of a machining time prediction device according to the first embodiment of the present disclosure.

[0038] Figure 2 It is a block diagram of the transfer function of the axis motion simulation unit when the axis of the axis motion simulation unit is a feed axis.

[0039] Figure 3 It is a block diagram of the transfer function of the axis motion simulation unit when the axis of the axis motion simulation unit is a spindle.

[0040] Figure 4 It is a block diagram showing the structure of the axis motion simulation unit when the axis of the axis motion simulation unit is a spindle.

[0041] Figure 5 It is a diagram showing a drive system composed of a motor, a coupling, and a ball screw.

[0042] Figure 6 It is a characteristic diagram showing the relationship between the frictional torque and the angular velocity of the motor.

[0043] Figure 7 It is a structural diagram showing the structure of a machining center for machining a turbine blade W.

[0044] Figure 8 It is a characteristic diagram for explaining the in-position check.

[0045] Figure 9 It is a characteristic diagram for explaining the stop judgment width of the speed.

[0046] Figure 10 It is a characteristic diagram for explaining the arrival width of the speed and the waiting time until the speed enters the arrival width.

[0047] Figure 11It is a characteristic diagram showing the X-axis command speed, the X-axis speed output from the slave axis motion simulation unit, and the waiting time.

[0048] Figure 12 It is a flowchart showing the machining time prediction operation of the machining time prediction device.

[0049] Figure 13 It is a block diagram showing the structure of the machining time prediction device according to the second embodiment of the present disclosure.

[0050] Figure 14 It is a block diagram showing the structure in which the Z-axis motion simulation unit operates following the operation of the main axis motion simulation unit.

[0051] Figure 15 It is a diagram showing an example of a structure in which the X-axis motion simulation unit and the Z-axis motion simulation unit are connected to the same DC bus.

[0052] Figure 16 It is a characteristic diagram showing the relationship between the maximum torque and the rotational speed of the motor.

[0053] Figure 17 It is a characteristic diagram showing the waiting time predicted by applying the τmax set for the region R1 to the region R2 and the waiting time considering the N-T characteristics. Detailed Embodiment

[0054] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings.

[0055] (First Embodiment)

[0056] Figure 1 It is a block diagram showing the structure of the machining time prediction device according to the first embodiment of the present disclosure.

[0057] The machining time prediction device 10 includes: an analysis unit 100, an execution control unit 200, an axis control unit 300, an axis motion simulation unit 400, and a machining time prediction unit 500. The execution control unit 200 includes an interpolation unit 201 and a motion completion determination unit 202. The machining time prediction device 10 predicts the machining time (execution time of the machining program) of a machine tool that controls at least one axis to machine a workpiece according to the machining program.

[0058] The analysis unit 100, the interpolation unit 201, and the axis control unit 300 constitute a numerical control device (hereinafter, referred to as an NC device). The motion completion determination unit 202 can be provided together with the interpolation unit 201 inside the NC device or outside the NC device. The machining time prediction unit 500 can also be provided inside the NC device.

[0059] Hereinafter, each unit constituting the machining time prediction device 10 will be described.

[0060] The analysis unit 100 interprets an NC (Numerical Control) program that is a machining program for positioning a specified feed axis and controlling the speed of a spindle, decomposes the NC program into respective codes and values, and calculates the movement distance, movement path, and commanded speed (which becomes the axis movement command).

[0061] The execution control unit 200 includes an interpolation unit 201 and a motion completion determination unit 202.

[0062] The interpolation unit 201 summarizes the execution of the motion commands and indicates the axis movement based on the result obtained by analyzing the NC program. Specifically, based on the movement distance, movement path such as a straight line or an arc, and commanded speed obtained by the analysis unit 100, interpolation data (which becomes the axis movement indication) obtained by interpolating points on the movement path at an interpolation cycle is generated and output to the axis control unit 300.

[0063] The motion completion determination unit 202 determines the completion of the axis movement based on the control command output from the axis control unit 300 or the axis motion simulation unit 400 and the virtual actual results output from the axis motion simulation unit 400. The virtual actual results are, for example, the position, position deviation, speed, or speed deviation of the feed axis and the spindle speed output from the axis motion simulation unit 400. The motion completion determination unit 202, based on the virtual actual results, performs, for example, confirmation of the completion of the movement command (positioning) for the feed axis and confirmation of the completion of the speed change (speed change) for the spindle. The details of the motion based on the motion completion confirmation by the motion completion determination unit 202 will be described later.

[0064] The axis control unit 300 generates a control command based on the axis movement indication from the interpolation unit 201 and outputs it to the axis motion simulation unit 400. Specifically, the axis control unit 300 generates an acceleration / deceleration curve based on the interpolation data and distributes it to each control axis. Thereby, the position command value or speed command value for each control cycle of the servo motor that is the motor of the feed axis and the spindle motor that is the motor of the spindle is given to the axis motion simulation unit 400.

[0065] The axis motion simulation unit 400 performs servo control for driving the motors of the feed axis and the spindle to follow the position command value or speed command value and simulates the movement of the machine tool, and outputs the virtual actual results to the motion completion determination unit 202. In addition, the axis motion simulation unit 400 outputs control commands such as the position command value and speed command value to the motion completion determination unit 202. The details of the axis motion simulation based on the axis motion simulation unit 400 will be described later.

[0066] The machining time prediction unit 500 uses the moving distance, moving path, commanded speed, etc. obtained by the analysis unit 100 to calculate the commanded time of the machining program, and predicts the machining time (execution time of the machining program) based on the calculated commanded time, the control commands output from the axis control unit 300 or the motion completion determination unit 202, and the waiting time calculated from the completion confirmation notification from the motion completion determination unit 202. In addition, the control commands input to the machining time prediction unit 500 may also be output from the axis control unit 300 or the axis motion simulation unit 400. The details of the prediction operation of the machining time based on the machining time prediction unit 500 will be described later.

[0067] The waiting time, for example, refers to the time from when the speed command value is set to speed "0" (stop) until deceleration and reaching the position range of the specified width or the stop determination width range where it is determined to be stopped at speed "0". Additionally, the waiting time, for example, refers to the time from when the speed command value is set to the target speed until the speed increases and reaches the arrival width range of the set target speed.

[0068] When the machining time prediction unit 500 repeatedly issues commands for axis acceleration and stop in the machining program, it adds the sum of the commanded times and the sum of the waiting times to predict the machining time.

[0069] Next, the axis motion simulation unit 400, the motion completion determination unit 202, and the machining time prediction unit 500 will be further described.

[0070] (Axis motion simulation unit 400)

[0071] The axis motion simulation unit 400 performs simulation of the motions of the feed axis that depicts the trajectory based on the machining program and the spindle that rotates the tool or workpiece.

[0072] When the axis is a feed axis, for example, the axis motion simulation unit 400 is represented by Figure 2 the block diagram of the transfer function. A block diagram with the same structure as the Figure 2 block diagram is described in Japanese Patent Laid-Open No. 3-110607.

[0073] The transfer function of the axis motion simulation unit 400 is composed of the combination of transfer functions 401 to 407.

[0074] In Figure 2 , the transfer function 401 is the transfer function of the position loop, and Kp represents the position gain. The transfer function 402 is the transfer function of the speed loop, and k 1 represents the integral gain, and k 2 represents the proportional gain. The transfer functions 403 and 404 are the transfer functions of the motor. K tRepresents the torque constant, J m Represents the motor inertia (moment of inertia). The transfer function 405 represents the combination of the servo motor and the machine, such as the ball screw, etc. The transfer function 406 is the transfer function of the machine, J L Represents the inertia of the machine. The transfer function 407 is the transfer function of the integral element that integrates the speed of the movable part of the machine to obtain the position of the machine.

[0075] The position loop represented by the transfer function 401 and the speed loop represented by the transfer function 402 form the servo control model, and the motor, ball screw, etc. and the integral element represented by the transfer functions 403, 404, 405, 406, and 407 are the equipment models.

[0076] The angular velocity of the servo motor can be obtained from the differential equation of Mathematical Formula 1 (the following Mathematical Formula 1).

[0077] The numerical solution method using this differential equation is included in the equipment model.

[0078] In Mathematical Formula 1, ω represents the angular velocity, τ represents the torque, and J m Represents the motor inertia.

[0079] [Mathematical Formula 1]

[0080] dω / dt = τ(t) / J m

[0081] Subtract the feedback signal P of the position of the machine detected by the linear scale, etc. from the position command Pc output by the axis control unit 300 f to obtain the position deviation, and multiply this position deviation by the position gain Kp to obtain the speed command V c . From this speed command V c subtract the feedback value V of the motor speed detected by the pulse encoder, etc. installed on the servo motor f to obtain the speed deviation, and perform proportional integration to obtain the torque command T c (current command), and drive the servo motor according to the torque command Tc. The servo motor performs position and speed feedback control in a closed-loop manner.

[0082] In addition, the axis motion simulation unit 400 can also have the following structure: The transfer function 407 integrates the angular velocity of the servo motor to obtain the angle of the servo motor, and regards the value obtained by converting the angle of the servo motor into the position of the machine as the position of the machine.

[0083] The axis motion simulation unit 400, for example, when the axis is the main shaft, is represented by the block diagram of the transfer function Figure 3 . The block diagram shown corresponds to removing the part related to Figure 3 and Figure 2Feedback signal P of the mechanical position of the shown block diagram f Block diagram of the loop-related transfer functions 401 and 407

[0084] Figure 3 The shown transfer functions 402, 403, and 404 are the same as Figure 2 the shown transfer functions 402, 403, and 404 Figure 3 The motors shown by the transfer functions 403 and 404 are servo motors or induction motors

[0085] Figure 3 The transfer function 406 is the transfer function of the main shaft. Regarding Figure 3 the transfer function 405, at the junction of the motor and the main shaft, there are cases where the rotation shaft of the motor is directly coupled to the main shaft through a coupling, and there are also cases where the rotational speed of the motor is decelerated or accelerated through a gear mechanism or a belt pulley mechanism and transmitted to the main shaft. The output of the transfer function 404 of the motor outputs a value Vf obtained by converting the angular velocity of the motor into the rotational speed of the main shaft, and the transfer function 402 of the speed loop performs speed control in such a way that the main shaft speed command Vc is made consistent with the output Vf of the transfer function 404

[0086] In addition Figure 3 is a structure in which the output of the transfer function 406 is set to Vf, and also functions as a main shaft motion simulation unit

[0087] And regarding Figure 3 even if the transfer function 405 and the transfer function 406 are removed, if Jm is set to the sum of the motor inertia and the main shaft inertia, it also functions as a main shaft motion simulation unit

[0088] The shaft motion simulation unit 400 is represented by the block diagram of Figure 4 for example when the shaft is the main shaft and the motor is an induction motor. A block diagram with the same structure as Figure 4 the block diagram is described in Japanese Patent Application Laid-Open No. 2020-5406 Figure 4 The shown block diagram removes the proximity switch, the rotational speed calculation unit using the detection pulse number of the proximity switch, and the speed command correction unit shown in the block diagram described in Japanese Patent Application Laid-Open No. 2020-5406. Except for the proximity switch, the rotational speed calculation unit using the detection pulse number of the proximity switch, and the speed command correction unit, the structure and operation of the shaft motion simulation unit 400 are the same as those described in Japanese Patent Application Laid-Open No. 2020-5406, so detailed description is omitted

[0089] As Figure 4As shown, the shaft motion simulation unit 400 includes: a subtractor 411, a speed control unit 412, a current control unit 413, a primary frequency control unit 414, a slip frequency calculation unit 415, a subtractor 416, a two-phase to three-phase conversion unit 417, and an induction motor 418.

[0090] The subtractor 411 calculates the difference between the speed command value output from the shaft control unit 300 and the rotational speed estimation value output from the subtractor 416 described later, and outputs a speed deviation.

[0091] The speed control unit 412 generates a current command value (torque command value) by performing, for example, PI (proportional, integral) control on the speed deviation obtained by the subtractor 411.

[0092] The current control unit 413 generates a voltage command value (d-phase voltage command value and q-phase voltage command value) based on the current command value (torque command value) generated by the speed control unit 412 and the drive current value of the induction motor 418 described later.

[0093] The primary frequency control unit 414 generates a primary frequency command value based on the current command value (torque command value) generated by the speed control unit 412.

[0094] The slip frequency calculation unit 415 calculates a slip frequency estimation value based on the current command value (torque command value) generated by the speed control unit 412.

[0095] The subtractor 416 calculates the difference between the primary frequency command value from the primary frequency control unit 414 and the slip frequency estimation value calculated by the slip frequency calculation unit 415, and outputs it as the rotational speed calculation value of the induction motor 418.

[0096] The two-phase to three-phase conversion unit 417 converts the d-phase voltage command value and q-phase voltage command value generated by the current control unit 413 into voltage command values for each of the U, V, and W phases based on the primary frequency command value from the primary frequency control unit 414, thereby generating a voltage command value for driving the induction motor 418.

[0097] The drive current value of the induction motor 418 can be calculated, for example, by substituting the previously generated voltage command value as the voltage into the state equation of the induction motor 418. The state equation of the induction motor and the calculation method of the current are described, for example, in the non-patent literature by Murata, Tsuchiya, and Takeda, "Primary Linkage Flux Vector Control of Induction Motors", Transactions of the Institute of Measurement and Control Engineers, Vol. 25, No. 11, P1194 - 1201 (1989).

[0098] In addition, the angular velocity of the motor considering friction can be calculated as follows.

[0099] As Figure 5As shown, if we consider the drive system composed of the motor 4001, the coupling 4002, the ball screw 4003, and the workbench 4004, the frictional torque f acting on the motor 4001 m is represented by Mathematical Formula 2 (the following Mathematical Formula 2), and the frictional torque f m and the angular velocity ω of the motor m are related by Figure 6 a characteristic diagram.

[0100] In Mathematical Formula 2, J m represents the sum of the inertia moments of the rotor of the motor, the coupling, and the ball screw, and ω m represents the angular velocity of the motor. An analog simulation is performed to update the angular velocity ω m by time Δt. The number of updates is denoted as k, and the angular velocity at time kΔt is denoted as ω m [k].[[]END]]

[0101] [Mathematical Formula 2]

[0102] f m [k] = C 1m ω m [k - 1] + F m (C 2m ω m [k - 1] > F m )

[0103] f m [k] = C 1m ω m [k - 1] - F m (C 2m ω m [k - 1] < F m )

[0104] f m [k] = C 1m ω m [k - 1] + C 2m ω m [k - 1]

[0105] (C 2m ω m [k - 1] > F m , C 2m ω m [k - 1] < F m except)

[0106] If the subscript of Mathematical Formula 2 and Figure 6 is replaced from "m" to "L", the frictional torque f L [k] acting on the workbench can be obtained. JL is the value obtained by converting the mass of the workbench into an inertia moment, and ωL This is the value obtained by converting the speed of the workbench into angular velocity.

[0107] The torque τm[k] applied to the motor and the torque τL[k] applied to the workbench are obtained using Mathematical Formula 3. In Mathematical Formula 3, τin is the input torque supplied to the motor, and Ks is the torsional rigidity between the motor and the workbench.

[0108] [Mathematical Formula 3]

[0109] τ m [k] = τ in [k] - K s δ[k] - f m [k]

[0110] τ L [k] = K s δ[k] - f L [k]

[0111] δ[k] = Δt(ω m [k - 1] - ω L [k - 1]) + δ[k - 1]

[0112] Using the torque τ m [k] and the torque τ L [k] shown in Mathematical Formula 3, the relationship of Mathematical Formula 4 (the following Mathematical Formula 4) is obtained. In Mathematical Formula 4, ω m is the angular velocity of the motor, and ω L is the angular velocity obtained by converting the speed of the workbench into angular velocity and is the torque applied to the motor.

[0113] [Mathematical Formula 4]

[0114]

[0115] The static friction F is the main cause of deteriorating servo controllability at low speeds. Therefore, by considering the static friction in the calculation of angular velocity, the prediction accuracy of the action completion waiting time described later can be improved.

[0116] For example, in the case where the axis is a contour control rotary axis, the axis motion simulation unit can change whether the axis motion simulation is a feed axis or a spindle according to the commands of the machining program.

[0117] Regarding the definition of a contour control rotary axis, for example, in "9. Ideas on Contour Control Rotary Axes and Indexing Axes (July 24, 2018)" at https: / / www.jmtba.or.jp / exportcontrol, "An axis with an axis name, controlled by a numerical control device (NC) on the machine tool main body side, intended for turning, milling, grinding (hereinafter referred to as "cutting"), and satisfying all of the following is a rotary axis capable of contour control.

[0118] (1) An axis capable of using rotational motion as a cutting feed

[0119] (2) An axis capable of simultaneously performing cutting feed commands with other linear axes and rotary axes

[0120] (3) An axis that performs an interpolation motion along a specified path when commands are given simultaneously with other linear axes and rotary axes".

[0121] As an example of a contour control rotary axis, for example, there is a machining center for machining a turbine blade W described in Japanese Patent Laid-Open No. 2014-121746.

[0122] Figure 7 It is a structural diagram showing the structure of a machining center for machining a turbine blade W.

[0123] Figure 7 The shown machining center has a pair of tables 421a, 421b having clamping mechanisms 424a, 424b capable of holding a turbine blade W, and a table 423 capable of mounting a tool T. Servo motors 422a, 422b for rotating an axis (not shown) are built into each of the tables 421a, 421b. And, the table 421a is set in a posture capable of rotating the axis around an A1 axis parallel to the horizontal axis. On the other hand, the table 421b is set in a posture where the clamping mechanisms 424a, 424b face each other and the main spindle can rotate around an A2 axis coaxial with the A1 axis.

[0124] The table 421b can slide in the U-axis direction parallel to the A1 axis and the A2 axis (which is also the Figure 1 X axis in Figure 7 ). In addition, the table 423 can rotate around a B axis parallel to the front-back direction (Y-axis direction in

[0125] ). And, the tool T is mounted on a main spindle (not shown) inside the table 423 and can rotate together with the main spindle by a servo motor (not shown). Figure 7In a machining center, a machining program for machining a workpiece W into a turbine blade is executed. When machining the blade portion, the A1 axis and the A2 axis act as feed axes. A rotary tool T such as an end mill is used to machine the blade shape at the center of the workpiece. On the other hand, when machining the cylindrical shape at the end of the workpiece, the A1 axis and the A2 axis act as spindle axes. A turning operation is performed on the rotating workpiece W using a tool T such as a turning tool. That is, the A1 axis and the A2 axis are rotating axes driven by servo motors 422a and 422b, and according to the commands of the machining program, they become feed axes or spindle axes in the middle of the machining program.

[0126] (Operation completion determination unit 202)

[0127] As already described, the operation completion determination unit 202 determines the completion of the operation based on the control commands output from the axis control unit 300 or the axis motion simulation unit 400 and the virtual actual results output from the axis motion simulation unit 400.

[0128] (1) Judgment operation for completion of operation at stop

[0129] When the speed command value is set to speed "0" (stop), the operation completion determination unit 202 determines the completion of the operation based on whether the feed axis or the spindle axis has been decelerated and entered the position range of the specified width, or whether it has entered the stop determination width of the stop determined to be speed "0".

[0130] Regarding whether the feed axis or the spindle axis has been decelerated and entered the position range of the specified width, the operation completion determination unit 202 determines the positioning of the feed axis or the spindle axis through in-position inspection. When the speed command value is set to speed "0" (stop), the operation completion determination unit 202 performs in-position inspection, and if it enters in-position, it determines that the operation is completed. In-position means that the motor has reached within the width of the commanded position.

[0131] Figure 8 It is a characteristic diagram for explaining the in-position inspection. Figure 8 The shown characteristic diagram shows the relationship between the X-axis speed command and the position deviation amount at time T and time T. The position deviation amount is the virtual actual result.

[0132] The motion completion determination unit 202 sequentially obtains the speed command value of the X-axis at time T from the axis control unit 300 or the axis motion simulation unit 400, and also sequentially obtains the position deviation amount at time T from the axis motion simulation unit 400. Then, when the X-axis speed command value becomes the speed "0" (stop) in the block Nxx of the machining program, the motion completion determination unit 202 performs the in-position check. If the position deviation amount becomes less than or equal to the preset in-position width, it is determined that the motion is completed, and the motion completion confirmation is notified to the interpolation unit 201. When the interpolation unit 201 receives the notification of the motion completion confirmation, it starts the motion of the next block Nyy. In Figure 8 in the block Nxx of the machining program, the period from when the X-axis speed command value becomes the speed "0" (stop) until the start of the motion of the next block Nyy is referred to as the in-position check.

[0133] In addition, the motion completion determination unit 202 notifies the machining time prediction unit 500 of the motion completion confirmation. When the machining time prediction unit 500 receives the notification of the motion completion confirmation, it identifies the end of the block Nxx and measures the machining time.

[0134] The motion completion determination unit 202 may determine the motion completion during deceleration not by the in-position check but by the speed entering the stop determination width.

[0135] Figure 9 is a characteristic diagram for explaining the stop determination width of the speed.

[0136] The motion completion determination unit 202 sequentially obtains the speed of the X-axis at time T from the axis motion simulation unit 400. And when the speed of the X-axis enters the preset stop determination width and the vibration of the speed converges within the stop determination width a specified number of times, the motion completion determination unit 202 determines that the motion is completed and notifies the motion completion confirmation to the interpolation unit 201. When the interpolation unit 201 receives the notification of the motion completion confirmation, it starts the motion of the next block.

[0137] In addition, the motion completion determination unit 202 notifies the machining time prediction unit 500 of the motion completion confirmation. When the machining time prediction unit 500 receives the notification of the motion completion confirmation, it identifies the end of the block and measures the machining time.

[0138] (2) Judgment action for motion completion during acceleration or deceleration

[0139] When the speed or spindle speed changes, the motion completion determination unit 202 performs a speed arrival check and determines the motion completion.

[0140] Figure 10 is a characteristic diagram for explaining the arrival width of the speed during acceleration and the waiting time until the speed enters the arrival width.

[0141] The motion completion determination unit 202 sequentially obtains the feed axis speed or the spindle speed at time T from the axis motion simulation unit 400. And when the feed axis speed or the spindle speed enters a preset arrival width, the motion completion determination unit 202 determines that the motion is completed and notifies the interpolation unit 201 of the motion completion confirmation.

[0142] In addition, the motion completion determination unit 202 notifies the machining time prediction unit 500 of the motion completion confirmation. When receiving the notification of the motion completion confirmation, the machining time prediction unit 500 measures the machining time.

[0143] Even during deceleration, when the feed axis speed or the spindle speed enters a preset arrival width, the motion completion determination unit 202 can determine that the motion is completed.

[0144] (Machining time prediction unit 500)

[0145] The machining time prediction unit 500 measures the time required for the execution of the machining program to predict the machining time.

[0146] For example, as described above, the machining time prediction unit 500 uses the moving distance, the moving path, the command speed, etc. obtained by the analysis unit 100 to calculate the command time of the machining program, and based on the calculated command time, the control command output from the axis control unit 300 or the motion completion determination unit 202, and the waiting time obtained according to the notification of the completion confirmation from the motion completion determination unit 202, measures the time required for the execution of the machining program and predicts the machining time.

[0147] The machining time can be obtained by the sum of the command time and the waiting time.

[0148] Figure 11 It is a characteristic diagram showing the X-axis command speed, the X-axis speed output from the axis motion simulation unit, and the waiting time.

[0149] A method for obtaining the command time of a machining program using the analysis result in the analysis unit 100 can be carried out using a known technique, for example, the technique related to a machining time prediction device disclosed in Japanese Patent Application Laid-Open No. 2012-093975. Japanese Patent Application Laid-Open No. 2012-093975 discloses a machining time prediction device having: an NC command interpretation unit that interprets NC commands; a segment data generation unit that divides a tool path into small slices, i.e., segments; an intermediate memory that stores segment data; a speed limit processing unit that obtains the speed in the tangential direction of a segment; a segment movement time calculation unit that calculates the time required for the tool to move in each segment based on the speed obtained by the speed limit processing unit; and a total movement time calculation unit that takes the sum of the times for moving each segment as the tool movement time, and this machining time prediction device calculates the time required for the tool to move along the path specified by the NC command.

[0150] A method for obtaining the waiting time at stop is, for example, as Figure 11 shown, obtained by taking the difference between the time t2 when the action completion is judged by the action completion judgment unit 202 and the time t1 when the speed of the X-axis command speed becomes "0" (stop). A method for obtaining the waiting time during acceleration can be carried out in the same way.

[0151] When the machining time prediction unit 500 repeatedly issues commands for axis acceleration and stop in a machining program, it adds the sum of the command times and the sum of the waiting times (total command time and waiting time) to predict the machining time.

[0152] The time required for the execution of a machining program is, for example, from the start of the analysis of the machining program to the time when the last program block of the machining program is judged to be action completed. Regarding how to set the respective timings of the start and completion of the execution of the machining program, in addition to the above example of obtaining the machining time by the sum of the command time and the waiting time, several implementation modes can be conceived. In view of the fact that the present invention is completed by focusing on the command time of the axis movement and the action completion waiting time, no matter whether the execution start is set to any one before the command start time of the first axis movement, or the execution completion is set to any one after the action completion judgment of the last axis movement, it will not have any impact on the gist of the invention.

[0153] Above, the structure of the machining time prediction device 10 has been described. Next, regarding the machining time prediction operation of the machining time prediction device 10, taking the case where commands for axis acceleration and stop are repeatedly issued in a machining program as an example, it will be described using a flowchart.

[0154] Figure 12 is a flowchart showing the operation of the machining time prediction device 10.

[0155] In step S11, the analysis unit 100 interprets the NC program to obtain the moving distance, moving path, and commanded speed. Then, the interpolation unit 201 generates interpolation data, and the axis control unit 300 generates a position command value or a speed command value based on the interpolation data.

[0156] In step S12, the axis motion simulation unit 400 performs servo control to make the drives of the motors driving the feed axes and the spindle follow the position command value or the speed command value and simulates the operation of the machine tool, and outputs virtual actual results to the motion completion determination unit 202.

[0157] In step S13, based on the commands output from the interpolation unit 201 and the virtual actual results output from the axis motion simulation unit 400, it is determined whether the operation is completed.

[0158] In step S14, the machining time prediction unit 500 uses the interpolation data obtained by the interpolation unit 201 to obtain the command time of the machining program. In addition, the waiting time is obtained based on the notification of completion confirmation from the motion completion determination unit 202.

[0159] In step S15, the machining time prediction unit 500 adds the sum of the command times and the sum of the waiting times (total command time and waiting time) to predict the machining time.

[0160] (Second Embodiment)

[0161] Figure 13 is a block diagram showing the configuration of the machining time prediction device according to the second embodiment of the present disclosure.

[0162] Figure 13 The shown machining time prediction device 10A compared with Figure 1 the shown machining time prediction device 10, the axis control unit 300 is divided into an X-axis control unit 300A, a Z-axis control unit 300B, and a spindle control unit 300C, the axis motion simulation unit 400 is divided into an X-axis motion simulation unit 400A, a Z-axis motion simulation unit 400B, and a spindle motion simulation unit 400C, and a model setting unit 600 is added. In addition, the machining time prediction device 10A divides the interpolation unit 201 into a feed axis interpolation unit 201A and a spindle command unit 203 to perform function separation.

[0163] The model setting unit 600 sets the constants of the simulation models of the X-axis motion simulation unit 400A, the Z-axis motion simulation unit 400B, and the spindle motion simulation unit 400C. For example, when the simulation models of the X-axis motion simulation unit 400A and the Z-axis motion simulation unit 400B are represented by Figure 2 the block diagram of the transfer function of, set the integral gain k 1 , the proportional gain k 2 , the torque constant K t , the motor inertia Jm 、The inertia J of the machine L and other constants.

[0164] The feed axis interpolation unit 201A and the spindle command unit 203 can perform actions that refer to virtual actual results with each other. For example, the spindle command unit 203 refers to the virtual actual results output from the Z-axis motion simulation unit 400B in the case of performing a constant peripheral speed control in lathe machining where the rotational speed increases as it gets closer to the center. The feed axis interpolation unit 201A refers to the virtual actual results output from the spindle motion simulation unit 400C in the case of rigid tapping control where interpolation is performed simultaneously on the spindle and the feed axis to precisely synchronize the rotation of the tool and its movement in the Z-axis.

[0165] (First modification example)

[0166] In a machine tool, it is sometimes required that the servo control unit of the feed axis controls the feed motion of the feed axis to follow the motion of the spindle. For example, in the case of controlling synchronous operation (so-called master-slave synchronous mode), regarding the synchronous operation, the feed axis operates in a manner that follows the rotational motion of the spindle while considering the pitch specified by the tapping machining program.

[0167] Use Figure 14 To describe the structure of axis motion simulation in the case of controlling the feed motion of the feed axis to follow the motion of the spindle.

[0168] Figure 14 It is a block diagram showing the structure of a modification example in which the Z-axis motion simulation unit 400B operates following the operation of the spindle motion simulation unit 400C. The Z-axis motion simulation unit 400B has the same structure as Figure 2 shown, and the structure of the spindle motion simulation unit 400C is the same as Figure 3 shown.

[0169] As Figure 14 shown, the rotational speed calculation value of the spindle (becoming the virtual actual result of other axes) is output from the rotational speed calculation unit 421 of the spindle motion simulation unit 400C to the Z-axis control unit 300B. The Z-axis control unit 300B calculates the motion amount of the feed axis that follows the motion of the spindle based on the rotational speed calculation value of the spindle, and outputs the Figure 2 position command P shown c (becoming the control command of the axis). The Z-axis control unit 300B accumulates the rotational speed calculation value of the spindle to obtain the rotational amount of the spindle, and by multiplying the rotational amount of the spindle by the pitch, it is possible to calculate the feed motion amount of the feed axis that follows the motion of the spindle.

[0170] (Second modification example)

[0171] In this modification example, for Figure 13An example in which the X-axis motion simulation unit 400A and the Z-axis motion simulation unit 400B of the shown machining time prediction device 10A are connected to the same DC bus will be described.

[0172] Figure 15 FIG. is a structural example showing that the X-axis motion simulation unit and the Z-axis motion simulation unit are connected to the same DC bus. Here, the X-axis motion simulation unit and the Z-axis motion simulation unit are connected to the same DC bus, but the X-axis motion simulation unit and the Z-axis motion simulation unit may also be connected to the DC bus separately.

[0173] Figure 15 The shown axis motion simulation unit has a plurality of machines driven by motors.

[0174] The X-axis motion simulation unit 400A includes: a servo control unit 441, an inverter 442, a motor 443, a coupling 444, a ball screw 445, and a worktable 446. The servo control unit 441 serves as a servo control model. The inverter 442, the motor 443, the coupling 444, the ball screw 445, and the worktable 446 serve as equipment models.

[0175] The Z-axis motion simulation unit 400B includes: a servo control unit 451, an inverter 452, a motor 453, a coupling 454, a ball screw 455, and a worktable 456. The servo control unit 451 serves as a servo control model. The inverter 452, the motor 453, the coupling 454, the ball screw 455, and the worktable 456 serve as equipment models.

[0176] The servo control unit 441 and the servo control unit 451 are respectively represented by Figure 2 the transfer function 401 of the position loop and the transfer function 402 of the speed loop. The motors 443 and 453 are respectively represented by Figure 2 the transfer functions 403 and 404 of the motors. The couplings 444 and the ball screws 445 and the couplings 444 and the ball screws 445 are respectively represented by Figure 2 the transfer function 405. The worktables 446 and 456 are respectively represented by Figure 2 the transfer function 406.

[0177] In addition, when the inverters 442 and 452 are not modeled, it is expressed as a delay element (1 / (T s +1)), or is expressed as direct (torque command = motor applied torque).

[0178] The AC voltage supplied from the AC power supply 431 is rectified by the rectifier 432, and the voltage rectified by the smoothing capacitor 433 is smoothed. The regenerative resistor 434 is used when surplus regenerative power is generated and the DC bus voltage (bus voltage) V DWhen the specified value is reached, the regenerative power is consumed. The regenerative transistor 435 becomes conductive when the bus voltage reaches the specified value, and the power stored in the smoothing capacitor 433 is consumed by the regenerative resistor 434. The DC bus is connected to the inverters 442 and 452, and the DC bus voltage V D is applied to the inverters 442 and 452. Figure 13 The model setting unit 600 shown in FIG. sets the capacitance value of the smoothing capacitor 433 and the resistance value of the regenerative resistor 434.

[0179] The DC bus voltage can be calculated from the AC voltage of the AC power supply 431, the capacitance value of the smoothing capacitor 433, the resistance value of the regenerative resistor 434, and the like.

[0180] The servo control unit 441 gives a voltage command to the inverter 442 according to the position command value or speed command value output from the X-axis control unit 300A. The servo control unit 451 gives a voltage command to the inverter 452 according to the position command value or speed command value output from the Z-axis control unit 300B.

[0181] The inverters 442 and 452 respectively perform PWM (Pulse Width Modulation) operations on the DC bus voltage V D and perform power conversion in such a way that the voltage command is applied to the motors 443 and 453, thereby supplying current to the motors 443 and 453.

[0182] As Figure 16 shown in the characteristic diagram, the maximum torque Tor of the motor varies according to the rotational speed N.

[0183] The N-T characteristic also varies according to the DC link voltage. When the DC link voltage drops, Figure 16 the region R1 shown in FIG. becomes narrower.

[0184] The relationship between the DC link voltage V D and the region R1 is as follows.

[0185] The R1 region is the region where the mathematical formula 5 (the following mathematical formula 5) holds. In the mathematical formula 5, τ LIM is the electrical and mechanical allowable torque of the motor, Kt is the torque constant, and Rm is the winding resistance.

[0186] [Mathematical formula 5]

[0187] T LIM <K t (V D -K t ω m ) / R m

[0188] In region R1, τ max = τ LIM , regarding migration to region R2, when mathematical formula 6 (the following mathematical formula 6) holds, it depends on the DC link voltage V D .

[0189] [Mathematical formula 6]

[0190]

[0191] In region R2, mathematical formula 7 (the following mathematical formula 7) holds, and τ max still depends on the DC bus voltage V D .

[0192] [Mathematical formula 7]

[0193] τ max = K t (V D - K t ω m ) / R m

[0194] In mathematical formula 4, if torsional rigidity, table inertia, and friction are ignored, the relationship of the angular velocity ω m shown in mathematical formula 8 is obtained. The relationship of the angular velocity ω m shown in mathematical formula 8 is obtained using the differential equation shown in mathematical formula 1.

[0195] [Mathematical formula 8]

[0196]

[0197] τ in is calculated by speed servo control, but cannot exceed the maximum value τ max determined by the N - T characteristic.

[0198] The spindle of a machine tool is often required to accelerate and decelerate between a low - rotation region and a high - rotation region at the maximum torque. At this time, compared with setting τ max to be constant and calculating ω m using mathematical formula 8, considering the N - T characteristic and calculating ω m using mathematical formula 8 will improve the prediction accuracy of the speed - reaching waiting time.

[0199] In Figure 17 , the time T1 represents the waiting time predicted by applying the τ max in region R1 to region R2 as well, and the time T2 is the waiting time considering the N - T characteristic.

[0200] According to the embodiments described above, without using actual machining data, accurate machining time prediction can be performed even when stop commands for axes frequently appear in the machining program and when axes with large inertia are mounted on the machine tool.

[0201] In addition, according to the embodiments, if a movement amount or a command point sequence is given to a peripheral axis that undertakes the actions of an auxiliary mechanism such as an automatic tool changer, the operation time prediction of the peripheral axis can be performed.

[0202] As described above, in order to implement the functional blocks included in the machining time prediction device in the present embodiment, the machining time prediction device can be implemented by hardware, software, or a combination thereof. Here, implementing by software means implementing by a computer reading and executing a program.

[0203] In order to implement the functional blocks included in the machining time prediction device in the present embodiment by software or a combination thereof, specifically, the machining time prediction device has an arithmetic processing device such as a CPU (Central Processing Unit). In addition, the machining time prediction device also has an auxiliary storage device such as an HDD (Hard Disk Drive) that stores various control programs such as application software or an OS (Operating System), and a main storage device such as a RAM (Random Access Memory) that stores data temporarily required when the arithmetic processing device executes a program.

[0204] And, in the machining time prediction device, the arithmetic processing device reads the application software or the OS from the auxiliary storage device, expands the read application software or OS in the main storage device, and performs arithmetic processing according to these application software or OS. In addition, according to the arithmetic result, various hardware included in each device is controlled. Thereby, the functional blocks of the present embodiment are implemented.

[0205] Each structural part included in the machining time prediction device can be implemented by hardware including an electronic circuit, etc. In the case where the machining time prediction device is constituted by hardware, for example, each structural part included in the machining time prediction device can be constituted by an integrated circuit (IC) such as an ASIC (Application Specific Integrated Circuit), a gate array, an FPGA (Field Programmable Gate Array), or a CPLD (Complex Programmable Logic Device) to implement part or all of the functions.

[0206] The program can be stored using various types of non-transitory computer readable media and provided to a computer. Non-transitory computer readable media include various types of tangible storage media. Examples of non-transitory computer readable media include magnetic recording media (e.g., hard disk drives), magneto-optical recording media (e.g., magneto-optical discs), CD-ROM (Compact Disc Read-Only Memory), CD-R, CD-R / W, semiconductor memories (e.g., mask ROM, PROM (Programmable ROM), EPROM (Erasable PROM), flash ROM, RAM (Random Access Memory)). Additionally, the program can also be provided to the computer through various types of transitory computer readable media.

[0207] The above-described embodiments are preferred embodiments of the present invention, but the scope of the present invention is not limited to the above embodiments, and various modifications can be made without departing from the gist of the present invention.

[0208] The machining time prediction device and the machining time prediction method of the present disclosure include the above-described embodiments and can adopt various embodiments having the following structures.

[0209] (1) A machining time prediction device (e.g., machining time prediction devices 10, 10A) that predicts the machining time of a machine tool that controls at least one axis to machine a workpiece based on a machining program, wherein

[0210] the machining time prediction device has:

[0211] an analysis unit (e.g., analysis unit 100) that analyzes the machining program and generates motion commands for the axis;

[0212] an execution control unit (e.g., execution control unit 200) that has an interpolation unit (e.g., interpolation unit 201) that summarizes the execution of the motion commands and indicates the motion of the axis according to the result obtained by analyzing the machining program, and a motion completion determination unit (e.g., motion completion determination unit 202) that determines the completion status of the motion of the axis;

[0213] an axis control unit (e.g., axis control unit 300) that generates a control instruction based on the motion instruction of the axis from the interpolation unit

[0214] A machining time prediction unit (e.g., the machining time prediction unit 500) that measures the time required for the execution of the machining program and predicts the machining time;

[0215] An axis motion simulation unit (e.g., the axis motion simulation unit 400) that simulates the motion of the axis according to the control instruction and outputs virtual actual results,

[0216] The motion completion determination unit determines the completion of the motion of the axis based on the virtual actual results.

[0217] According to this machining time prediction device, without using actual machining data, accurate prediction of machining time can be performed even when stop commands of the axis frequently appear in the machining program and when an axis with large inertia is mounted on the machine tool.

[0218] (2) The machining time prediction device according to (1) above, wherein the axis motion simulation unit performs simulation of the motion of the feed axis that depicts the trajectory based on the machining program and the spindle that rotates the tool or workpiece.

[0219] (3) The machining time prediction device according to (2) above, wherein the axis motion simulation unit acts in a manner to follow the motion of other axes based on the virtual actual results of the other axes.

[0220] (4) The machining time prediction device according to (2) or (3) above, wherein the machining time prediction device can change whether the axis motion simulation based on the axis motion simulation unit is performed on the feed axis or the spindle through commands in the machining program.

[0221] (5) The machining time prediction device according to any one of (1) to (4) above, wherein the machining time prediction device has: a model setting unit that can change the characteristics of the axis motion simulation unit,

[0222] The axis motion simulation unit has:

[0223] A servo control model that makes the virtual actual results follow the control instruction;

[0224] A device model that includes a numerical solution of one or more differential equations and calculates the virtual actual results when an operation amount that is an output of the servo control model is input.

[0225] (6) The machining time prediction device according to (5) above, wherein the device model includes: an electric motor that is driven by an inverter as a power source of the axis,

[0226] The machining time prediction device can calculate the DC bus voltage connected to the inverter.

[0227] (7) The machining time prediction device according to (6) above, wherein the axis motion simulation unit is provided for two or more axes respectively, and the inverters of the respective axis motion simulation units are connected to the same DC bus.

[0228] (8) A machining time prediction method, wherein the following processing is executed by a computer of a machining time prediction device that predicts the machining time of a machine tool that controls at least one axis to machine a workpiece according to a machining program:

[0229] A process of analyzing the machining program to generate motion commands for the axis;

[0230] A process of summarizing the execution of the motion commands, instructing the motion of the axis based on the result obtained by analyzing the machining program, and judging the completion of the motion of the axis;

[0231] A process of generating a control command based on the motion instruction of the axis;

[0232] A process of measuring the time required for the execution of the machining program to predict the machining time;

[0233] Axis motion simulation processing that simulates the motion of the axis based on the control command and outputs virtual actual results,

[0234] In the process of judging the completion of the motion of the axis, the completion of the motion of the axis is judged based on the virtual actual results.

[0235] According to this machining time prediction method, without using actual machining data, accurate prediction of the machining time can be performed even when stop commands for the axis frequently appear in the machining program and when the machine tool is equipped with an axis with large inertia.

[0236] Explanation of reference numerals

[0237] 10, 10A Machining time prediction device

[0238] 100 Analysis unit

[0239] 200 Execution control unit

[0240] 201 Interpolation unit

[0241] 202 Motion completion judgment unit

[0242] 300 Axis control unit

[0243] 400 Axis motion simulation unit

[0244] 500 Processing Time Prediction Unit

[0245] 600 Model Setting Unit.

Claims

1. An axis motion completion judgment device that judges the completion of the axis motion of a machine tool that controls at least one axis to machine a workpiece according to a machining program. Characterized in that: The machining time prediction device has: An analysis unit that analyzes the machining program and generates motion commands for the axis; An execution control unit that has an interpolation unit that summarizes the execution of the motion commands and indicates the motion of the axis according to the result obtained by analyzing the machining program, and a motion completion judgment unit that judges the completion situation of the axis motion; An axis control unit that generates a control command according to the axis motion indication from the interpolation unit; An axis motion simulation unit that, according to the control command, simulates feedback control through a servo control model and a device model and calculates the virtual actual performance of the axis motion; The motion completion judgment unit judges the completion of the axis motion according to the virtual actual performance.

2. The axis motion completion judgment device according to claim 1, Characterized in that: The axis motion simulation unit simulates the motions of the feed axis that depicts the trajectory based on the machining program and the spindle that rotates the tool or workpiece.

3. The axis motion completion judgment device according to claim 2, Characterized in that: The axis motion simulation unit acts in a manner of following the motions of other axes according to the virtual actual performance of other axes.

4. The axis motion completion judgment device according to claim 2 or 3, Characterized in that: The machining time prediction device can change whether it is the feed axis or the spindle that performs the axis motion simulation based on the axis motion simulation unit through the commands of the machining program.

5. The axis motion completion judgment device according to any one of claims 1 to 4, Characterized in that: The machining time prediction device has: a model setting unit that can change the characteristics of the axis motion simulation unit, The device model includes a numerical solution method of one or more differential equations.

6. The axis motion completion judgment device according to claim 5, Characterized in that: The device model includes: an electric motor that is driven by an inverter as the power source of the axis, The machining time prediction device can calculate the DC bus voltage connected to the inverter.

7. The axis motion completion judgment device according to claim 6, Characterized in that: The axis motion simulation unit is provided for each of two or more axes, and the inverters of each axis motion simulation unit are connected to the same DC bus.

8. An axis motion completion judgment method, Characterized in that: As an axis motion completion judgment device that judges the completion of the axis motion of a machine tool that controls at least one axis to machine a workpiece according to a machining program, a computer performs the following processing: A process of analyzing the machining program and generating motion commands for the axis; A process of summarizing the execution of the motion commands, indicating the motion of the axis according to the result obtained by analyzing the machining program, and judging the completion situation of the axis motion; A process of generating a control command according to the axis motion indication; An axis motion simulation process of simulating feedback control through a servo control model and a device model according to the control command and calculating the virtual actual performance of the axis motion. In the process of determining the completion of the operation of the shaft, the completion of the operation of the shaft is determined based on the virtual actual results.

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