Processing time prediction device and processing time prediction method

Abstract

An accurate prediction of machining time can be made without using data of actual machining. A machining time prediction device for a machine tool that controls at least one axis according to a machining program to machine a workpiece, wherein the machining time prediction device comprises: an analysis unit that analyzes the machining program to generate an axis motion command; an execution control unit that includes an interpolation unit that summarizes the execution of the motion command and indicates the axis motion according to the result obtained by analyzing the machining program, and an motion completion judgment unit that judges whether the axis motion is completed; an axis control unit that generates a control instruction according to the axis motion instruction; a machining time prediction unit that measures the time required for the execution of the machining program to predict the machining time; an axis motion simulation unit that simulates the axis motion according to the control instruction and outputs a virtual result, and a motion completion judgment unit that judges the completion of the axis motion according to the virtual result.

Description

Technical Field

[0001] The present invention relates to a processing time prediction device and a processing time prediction method for a machine tool, and in particular 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 processing program. Background Art

[0002] In order to perform machining efficiently, it is necessary to understand the time required for each process before machining. In particular, it is important to understand the time required to execute the machining program of the CNC machine tool.

[0003] Patent Document 1 describes a numerical control device that obtains the shortest predicted machining time within an allowable machining error.

[0004] Specifically, Patent Document 1 describes the following: speed data for a machining speed and precision data for a machining precision are specified, a program analysis unit generates interpolation data for a machining program, an interpolation unit interpolates according to the interpolation data based on the speed generated by the pre-interpolation acceleration / deceleration unit and generates interpolation data (ΔPn), and a post-interpolation acceleration / deceleration unit performs post-interpolation acceleration / deceleration on the interpolation data (ΔPn) to generate servo position instruction data (VCn). Patent Document 1 also describes the following: a servo simulation unit receives the servo position instruction data (VCn) and generates servo position data (Qn) that simulates an actual servo action, a machining time prediction unit can measure machining time by interpolating the data or counting the number of interpolation times, and a machining error prediction unit uses the interpolation data (ΔPn) and the servo position data (Qn) to calculate a predicted machining error.

[0005] Patent Document 2 describes a numerical control device that can predict machining time with high accuracy taking into account mechanical delay occurring in a machine.

[0006] Specifically, patent document 2 describes a numerical control device comprising: a base processing time prediction unit, which predicts the processing time without considering the acceleration and deceleration of the axis, that is, the base processing time, based on the processing program; an acceleration and deceleration times prediction unit, which predicts the acceleration and deceleration times of the axis during processing, based on the processing program; a data storage unit, which stores information related to the deviation time, wherein the deviation time is the processing time actually spent on the machine's processing, that is, the difference between the actual processing time and the base processing time predicted in the processing; a correction time calculation unit, which calculates the correction time for correcting the base processing time based on the acceleration and deceleration times predicted by the acceleration and deceleration times prediction unit and the information related to the deviation time stored in the data storage unit; and a processing time prediction unit, which calculates the predicted processing time obtained by correcting the base processing time with the correction time.

[0007] Patent Document 3 describes a machining time calculation device that can accurately calculate the time required for machining before machining.

[0008] Specifically, Patent Document 3 describes the following: a segmented trajectory calculation unit divides a designated tool trajectory at larger intervals for a portion with a smaller curvature, and as the curvature of the designated tool trajectory increases, a segmented trajectory divided at smaller intervals is obtained, and an axis control data calculation unit obtains an arbitrary position on each segmented trajectory when a tool is moved on each segmented trajectory at a speed according to a designated tool moving speed to process a workpiece, and a time change of the tool moving speed in each axis direction obtained at a predetermined time interval, as axis control data A. Patent Document 3 also describes that a processing required time calculation unit calculates a processing time for processing a designated range.

[0009] Prior art literature

[0010] Patent Literature

[0011] Patent Document 1: Japanese Patent Application Publication No. 2012-243152

[0012] Patent Document 2: Japanese Patent Application Publication No. 2017-207823

[0013] Patent Document 3: Japanese Patent Application Publication No. 2009-098981 Summary of the invention

[0014] Problems to be solved by the invention

[0015] When axis stop commands appear frequently in a machining program of a CNC machine tool, or when an axis with large inertia (large response time constant) is mounted on the machine tool, it is difficult to accurately predict the machining time.

[0016] Furthermore, if actual machining data is used for prediction of machining time, data collection requires time and effort.

[0017] Therefore, a machining time prediction device for a machine tool is desired that can accurately predict the machining time without using actual machining data even when axis stop commands frequently appear in a machining program or when the machine tool is equipped with an axis with large inertia.

[0018] Means for solving problems

[0019] A first representative aspect of the present disclosure is a machining time prediction device that predicts a machining time of a machine tool that controls at least one axis to machine a workpiece based on a machining program.

[0020] The processing time prediction device comprises:

[0021] An analyzing unit that analyzes the machining program and generates a motion command for the axis;

[0022] an execution control unit including an interpolation unit for controlling the execution of the motion command and instructing the motion of the axis according to a result of analyzing the machining program, and a motion completion determination unit for determining whether the motion of the axis is completed;

[0023] an axis control unit that generates a control instruction according to an operation instruction of the axis from the interpolation unit;

[0024] a machining time prediction unit that measures the time required for executing the machining program and predicts the machining time;

[0025] an axis motion simulation unit, which simulates the motion of the axis according to the control instruction and outputs a virtual result,

[0026] The operation completion determination unit determines the completion of the operation of the axis based on the virtual performance.

[0027] A second representative aspect of the present disclosure is a machining time prediction method, wherein a computer as a machining time prediction device predicts a machining time of a machine tool that controls at least one axis to machine a workpiece based on a machining program, and executes the following processing:

[0028] Analyzing the machining program to generate motion commands for the axis;

[0029] A process for summarizing the execution of the motion command, instructing the motion of the axis according to the result of analyzing the machining program, and determining whether the motion of the axis is completed;

[0030] generating a control instruction according to the axis motion instruction;

[0031] A process of measuring a time required for executing the machining program to predict the machining time;

[0032] Axis motion simulation processing for simulating the motion of the axis according to the control command and outputting a virtual result,

[0033] In the process of determining whether the operation of the axis is completed, the completion of the operation of the axis is determined based on the virtual performance.

[0034] Effects of the Invention

[0035] According to each aspect of the present disclosure, even when axis stop commands appear frequently in a machining program or when an axis with large inertia is mounted on a machine tool, accurate machining time prediction can be performed without using actual machining data. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] 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.

[0037] Figure 2 This is a block diagram of the transfer function of the axis motion simulation section when the axis of the axis motion simulation section is a feed axis.

[0038] Figure 3 This is a block diagram of the transfer function of the axis motion simulation section when the axis of the axis motion simulation section is a main axis.

[0039] Figure 4 This is a block diagram showing the configuration of the axis motion simulation unit when the axis of the axis motion simulation unit is a main axis.

[0040] Figure 5 This is a diagram showing a drive system consisting of a motor, a coupling, and a ball screw.

[0041] Figure 6 This is a characteristic diagram showing the relationship between the friction torque and the angular velocity of the motor.

[0042] Figure 7 1 is a structural diagram showing the structure of a machining center for machining a turbine blade W.

[0043] Figure 8 This is a characteristic diagram used to explain the seating check.

[0044] Fig. 9 This is a characteristic diagram for explaining the stop judgment width of the speed.

[0045] Fig.10 This is a characteristic diagram for explaining the speed arrival width and the waiting time until the speed reaches the arrival width.

[0046] Fig.11 This 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.

[0047] Fig.12 This is a flowchart showing the machining time prediction operation of the machining time prediction device.

[0048] Fig.13 It is a block diagram showing the structure of a machining time prediction device according to a second embodiment of the present disclosure.

[0049] Fig.14 This is a block diagram showing a structure in which the Z-axis motion simulation unit operates following the operation of the main-axis motion simulation unit.

[0050] Fig.15 This is a diagram showing a configuration example in which an X-axis motion simulation unit and a Z-axis motion simulation unit are connected to the same DC bus.

[0051] Fig.16 This is a characteristic diagram showing the relationship between the maximum torque and the rotation speed of the motor.

[0052] Fig.17 This is a characteristic diagram showing the waiting time predicted by applying τmax of the region R1 to the region R2 and the waiting time in consideration of the NT characteristic. DETAILED DESCRIPTION

[0053] Hereinafter, embodiments of the present disclosure will be described in detail using the drawings.

[0054] (First Embodiment)

[0055] 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.

[0056] 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 an motion completion judgment 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 based on a machining program.

[0057] 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 operation completion judgment unit 202 can be provided in the NC device together with the interpolation unit 201, or can be provided outside the NC device. The machining time prediction unit 500 can also be provided in the NC device.

[0058] Hereinafter, each unit constituting the machining time prediction device 10 will be described.

[0059] The analyzing unit 100 interprets an NC (Numerical Control) program that is a machining program that specifies the positioning of feed axes and the speed control of spindles, decomposes the NC program into codes and values, and obtains a moving distance, a moving path, and a command speed (which becomes an axis motion command).

[0060] The execution control unit 200 includes an interpolation unit 201 and an operation completion determination unit 202 .

[0061] The interpolation unit 201 generally executes the motion command and instructs the axis motion according to the result obtained by analyzing the NC program. Specifically, based on the moving distance, straight line or circular arc moving path, and command speed obtained by the analysis unit 100, the interpolation data (which becomes the axis motion instruction) obtained by interpolating the points on the moving path at the interpolation cycle is generated and output to the axis control unit 300.

[0062] The action completion judgment unit 202 judges the completion of the action of the axis based on the control command output from the axis control unit 300 or the axis action simulation unit 400 and the virtual performance output from the axis action simulation unit 400. The virtual performance is, for example, the position, position deviation, speed or speed deviation of the feed axis and the spindle speed output from the axis action simulation unit 400. The action completion judgment unit 202 performs, based on the virtual performance, for example, action completion confirmation for the movement command (positioning) relative to the feed axis and action completion confirmation for the spindle speed change (speed change). The details of the action based on the action completion confirmation by the action completion judgment unit 202 will be described later.

[0063] The axis control unit 300 generates a control command based on the axis motion instruction 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 giving the position command value or speed command value of each control cycle of the servo motor that becomes the motor of the feed axis and the spindle motor that becomes the motor of the spindle to the axis motion simulation unit 400.

[0064] The axis motion simulation unit 400 performs servo control to make the drive of the motor driving the feed axis and the main axis follow the position command value or the speed command value and simulates the motion of the machine tool, and outputs the virtual performance to the motion completion judgment unit 202. In addition, the axis motion simulation unit 400 outputs control commands such as the position command value and the speed command value to the motion completion judgment unit 202. The details of the axis motion simulation by the axis motion simulation unit 400 will be described later.

[0065] The machining time prediction unit 500 uses the moving distance, moving path, and command speed obtained by the analysis unit 100 to obtain the command time of the machining program, and predicts the machining time (execution time of the machining program) based on the obtained command time and the waiting time obtained based on the control command output from the axis control unit 300 or the motion completion judgment unit 202 and the completion confirmation notification from the motion completion judgment unit 202. In addition, the control command 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 machining time prediction operation based on the machining time prediction unit 500 will be described later.

[0066] The waiting time refers to, for example, the time from when the speed command value is set to speed "0" (stop) to when the speed decelerates and reaches a position range of a specified width or a range of a stop judgment width determined as a stop of speed "0". In addition, the waiting time refers to, for example, the time from when the speed command value is set to a target speed to when the speed increases and reaches a range of a reach width of the speed set as the target.

[0067] When the acceleration and stop commands of the axis are repeatedly issued in the machining program, the machining time prediction unit 500 adds the total of the command time and the total of the waiting time to predict the machining time.

[0068] Next, the axis operation simulation unit 400 , the operation completion determination unit 202 , and the machining time prediction unit 500 will be further described.

[0069] (Axis motion simulation unit 400)

[0070] The axis operation simulation unit 400 simulates the operation of a feed axis that draws a trajectory based on a machining program and a spindle that rotates a tool or a workpiece.

[0071] For example, when the axis is a feed axis, the axis motion simulation unit 400 is Figure 2 The transfer function of is shown in the box-and-wire diagram. Figure 2 A block diagram of a similar structure is described in Japanese Patent Application Laid-Open No. 3-110607.

[0072] The transfer function of the axis motion simulation unit 400 is constituted by a combination of transfer functions 401 to 407 .

[0073] exist Figure 2 In FIG. 4 , transfer function 401 is the transfer function of the position loop, and Kp represents the position gain. Transfer function 402 is the transfer function of the speed loop, k1 represents the integral gain, and k2 represents the proportional gain. Transfer functions 403 and 404 are the transfer functions of the motor. K t Represents the torque constant, J m represents the motor inertia (inertia moment). Transfer function 405 represents the connection between the servo motor and the machine, i.e., the ball screw. Transfer function 406 is the mechanical transfer function, J L The transfer function 407 is a transfer function of an integral element for integrating the velocity of a movable part of the machine to obtain the position of the machine.

[0074] The position loop represented by transfer function 401 and the speed loop represented by transfer function 402 are servo control models, and the motor, ball screw, etc. and integral elements represented by transfer functions 403 , 404 , 405 , 406 , and 407 are device models.

[0075] The angular velocity of the servo motor can be obtained by a differential equation of Math Formula 1 (hereinafter referred to as Math Formula 1).

[0076] A numerical solution using this differential equation is included in the plant model.

[0077] In mathematical formula 1, ω represents angular velocity, τ represents torque, and J mIndicates the motor inertia.

[0078] [Mathematical formula 1]

[0079] dω / dt=τ9t) / J m

[0080] The feedback signal P of the mechanical position detected by a linear scale or the like is subtracted from the position command Pc outputted from the axis control unit 300. f The position error is obtained by multiplying the position error by the position gain Kp to obtain the speed command V c From the speed command V c Subtract the feedback value V of the motor speed detected by the pulse encoder installed in the servo motor f To find the speed deviation, and perform proportional integration to find the torque command T c (Current command), drives the servo motor according to the torque command Tc, and the servo motor performs position and speed feedback control in a closed loop manner.

[0081] Alternatively, the axis motion simulation unit 400 may be configured such that the transfer function 407 integrates the angular velocity of the servo motor to obtain the angle of the servo motor, and the value obtained by converting the servo motor angle into the position of the machine is regarded as the position of the machine.

[0082] The axis operation simulation unit 400 is, for example, a main axis. Figure 3 A block diagram representation of the transfer function. Figure 3 The box plot shown corresponds to the removal of Figure 2 The block diagram of the mechanical position feedback signal P is shown f A block diagram of the ring-related transfer functions 401 and 407.

[0083] Figure 3 The transfer functions 402, 403, 404 shown are Figure 2 The transfer functions 402, 403, 404 shown are identical. Figure 3 The motor shown in the transfer functions 403 and 404 is a servo motor or an induction motor.

[0084] Figure 3 The transfer function 406 is the transfer function of the main axis. Figure 3 The transfer function 405 of the motor and the spindle is that the motor's rotating shaft is directly connected to the spindle through a coupling, and the motor's rotation speed is decelerated or accelerated through a gear mechanism or a belt pulley mechanism and transmitted to the spindle. The transfer function 404 of the motor outputs a value Vf obtained by converting the motor's angular velocity into the spindle's rotation speed, and the transfer function 402 of the speed loop performs speed control in a manner that the spindle's rotation speed command Vc is consistent with the output Vf of the transfer function 404.

[0085] in addition, Figure 3 This is a configuration in which the output of the transfer function 406 is set to Vf, and also functions as a spindle operation simulation unit.

[0086] And, about 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 spindle inertia, it can function as a spindle operation simulation unit.

[0087] The axis motion simulation unit 400 is, for example, a main axis and an induction motor. Figure 4 The block diagram of Figure 4 A block diagram of the same structure is recorded in Japanese Patent Publication No. 2020-5406. Figure 4 The block diagram shown in the figure removes the proximity switch, the rotation speed calculation unit using the number of detection pulses 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 rotation speed calculation unit using the number of detection pulses of the proximity switch, and the speed command correction unit, the structure and operation of the axis motion simulation unit 400 are the same as those described in Japanese Patent Application Laid-Open No. 2020-5406, and therefore, detailed description is omitted.

[0088] like Figure 4 As 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 .

[0089] The subtractor 411 obtains a difference between a speed command value output from the axis control unit 300 and a rotation speed estimated value output from a subtractor 416 described later, and outputs a speed deviation.

[0090] 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 .

[0091] The current control unit 413 generates voltage command values ​​(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 a drive current value of an induction motor 418 described later.

[0092] 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 .

[0093] 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 .

[0094] The subtractor 416 obtains a difference between the primary frequency command value from the primary frequency control unit 414 and the slip frequency estimated value obtained by the slip frequency calculation unit 415 , and outputs the difference as a rotation speed calculation value of the induction motor 418 .

[0095] The two-phase to three-phase conversion unit 417 converts the d-phase voltage command value and the q-phase voltage command value generated by the current control unit 413 into voltage command values ​​of each phase, UV, and W, 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.

[0096] The driving current value of the induction motor 418 can be calculated, for example, by assigning the voltage command value generated last time as the voltage to the state equation of the induction motor 418. The state equation of the induction motor and the current calculation method are described in the non-patent literature, for example, Murata, Tsuchiya, and Takeda, "Primary Interlinkage Flux Vector Control of Induction Motors", Proceedings of the Society of Measurement and Automatic Control, Vol. 25, No. 11 P1194-1201 (1989).

[0097] In addition, the angular velocity of the motor in consideration of friction can be calculated as follows.

[0098] like Figure 5 As shown in FIG. 1 , if the drive system consisting of the motor 4001, the coupling 4002, the ball screw 4003 and the table 4004 is considered, the friction torque f acting on the motor 4001 is m According to Mathematical Formula 2 (hereinafter referred to as Mathematical Formula 2), the friction torque f m The angular velocity of the motor ω m The relationship is Figure 6 The characteristic diagram shows.

[0099] In mathematical formula 2, J m Represents the sum of the inertia moments of the motor’s rotor, coupling, and ball screw, ω m Represents the angular velocity of the motor. Update the angular velocity ω at time Δt m Simulation. Let the number of updates be k, and the angular velocity at time kΔt be ω m [k].

[0100] [Mathematical formula 2]

[0101] f m [k] = C 1m ω m [k-1]+F m (C2m ω m [k-1]>F m )

[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]+C 2m ω m [k-1]

[0104] (C 2m ω m [k-1]>F m , C 2m ω m [k-1] <F m outside)

[0105] If mathematical formula 2 and Figure 6 By replacing the subscript of from "m" to "L", the friction torque f acting on the table can be calculated. L [k]. J L is the value obtained by converting the mass of the worktable into the moment of inertia, ω L This is the value obtained by converting the speed of the table into angular velocity.

[0106] The torque τm[k] applied to the motor and the torque τL[k] applied to the table 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 table.

[0107] [Mathematical formula 3]

[0108] τ m [k] = τ in [k]-K s δ[k]-f m [k]

[0109] τ L [k] = K s δ[k]-f L [k]

[0110] δ[k]=Δt(ω m [k-1]-ω L [k-1])+δ[k-1]

[0111] Using the torque τ shown in mathematical formula 3 m [k] and torque τ L [k], find the relationship of Mathematical Formula 4 (hereinafter Mathematical Formula 4). In Mathematical Formula 4, ω m is the angular velocity of the motor, ω L The angular velocity obtained by converting the speed of the table into an angular velocity is applied to the torque of the motor.

[0112] [Formula 4]

[0113]

[0114] The static friction F is a factor that deteriorates the servo controllability at low speeds. Therefore, by taking the static friction into consideration in the calculation of the angular velocity, the prediction accuracy of the operation completion waiting time described later can be improved.

[0115] For example, when the axis is a contour control rotary axis, the axis motion simulation unit can change the axis motion simulation to a feed axis or a spindle by a command of a machining program.

[0116] Regarding the definition of contour-controlled rotary axes, for example, in "9. Concepts of contour-controlled rotary axes and indexing axes (July 24, 2018)" at https: / / www.jmtba.or.jp / exportcontrol, "An axis that has an axis name, is controlled by a numerical control device (NC) on the machine tool body side, is intended to perform turning, milling, or grinding (hereinafter referred to as "cutting"), and satisfies all of the following is a contour-controlled rotary axis.

[0117] (1) An axis that can use rotation as cutting feed

[0118] (2) An axis that can be cut and fed simultaneously with other linear axes or rotary axes

[0119] (3) An axis that performs interpolation along a specified path when commands are issued simultaneously with other linear axes or rotary axes.

[0120] As an example of a contour-controlled rotating axis, there is a machining center for machining a turbine blade W described in Japanese Patent Application Laid-Open No. 2014-121746.

[0121] Figure 7 1 is a structural diagram showing the structure of a machining center for machining a turbine blade W.

[0122] Figure 7The machining center shown in the figure has a pair of tables 421a and 421b with clamping mechanisms 424a and 424b capable of holding turbine blades W, and a table 423 capable of assembling a tool T, and each table 421a and 421b has a built-in servo motor 422a and 422b for rotating a shaft (not shown). In addition, the table 421a is set in a posture that allows the shaft to rotate around an A1 axis parallel to the horizontal axis. On the other hand, the table 421b is set in a posture that allows the main shaft to rotate around an A2 axis coaxial with the A1 axis so that the clamping mechanisms 424a and 424b face each other.

[0123] Table 421b can be oriented to the A1 axis and the A2 axis (also Figure 1 In addition, the stage 423 can slide in the direction of the U axis parallel to the X axis. Figure 7 The tool T is mounted on a spindle (not shown) inside the table 423 and can rotate together with the spindle through a servo motor (not shown).

[0124] exist Figure 7 In 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 operate as feed axes. The blade shape of the central portion of the workpiece is machined using a rotating tool T such as an end mill. On the other hand, when machining a cylindrical shape at the end of the workpiece, the A1 axis and the A2 axis operate as spindles. The rotating workpiece W is turned 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 become feed axes or spindles in the middle of the machining program according to the commands of the machining program.

[0125] (Action Completion Judgment Unit 202)

[0126] As described above, the operation completion determination unit 202 determines the completion of the operation based on the control command output from the axis control unit 300 or the axis operation simulation unit 400 and the virtual performance output from the axis operation simulation unit 400 .

[0127] (1) Action to determine if the action is completed when stopping

[0128] When the speed command value is set to speed "0" (stop), the action completion judgment unit 202 judges whether the action is completed based on whether the feed axis or the main axis is decelerated and enters the position range of the specified width, or whether it enters the range of the stop judgment width judged as the stop of speed "0".

[0129] The action completion judgment unit 202 determines whether the feed axis or spindle is decelerated and enters the position range of the specified width by judging the positioning of the feed axis or spindle through the in-position check. When the speed command value is set to speed "0" (stop), the action completion judgment unit 202 performs the in-position check and judges that the action is completed if it enters the in-position. In-position means that the motor reaches the width of the commanded position.

[0130] Figure 8 This is a characteristic diagram used to explain the seating check. Figure 8 The characteristic diagram shown shows the relationship between the time T and the X-axis speed command and the position deviation amount at the time T. The position deviation amount is a virtual result.

[0131] The action completion judgment unit 202 sequentially obtains the speed command value of the X-axis at time T from the axis control unit 300 or the axis action simulation unit 400, and also sequentially obtains the position deviation amount at time T from the axis action simulation unit 400. Furthermore, when the speed command value of the X-axis becomes speed "0" (stop) in the program block Nxx of the machining program, the action completion judgment unit 202 performs an in-position check. If the position deviation amount becomes less than the preset in-position width, it is judged that the action is completed, and the interpolation unit 201 is notified of the action completion confirmation. When the interpolation unit 201 receives the notification of action completion confirmation, it starts the action of the next program block Nyy. Figure 8 In the block Nxx of the machining program, the period from when the X-axis speed command value becomes speed "0" (stop) to when the action of the next block Nyy starts is represented as the in-position check.

[0132] In addition, the operation completion determination unit 202 notifies the operation completion confirmation to the machining time prediction unit 500. Upon receiving the operation completion confirmation notification, the machining time prediction unit 500 recognizes the end of the block Nxx and measures the machining time.

[0133] The operation completion determination unit 202 may determine the operation completion during deceleration by using the speed entry stop determination width instead of the in-position check.

[0134] Fig. 9 This is a characteristic diagram for explaining the stop judgment width of the speed.

[0135] The motion completion judgment unit 202 sequentially obtains the speed of the X axis at time T from the axis motion simulation unit 400. Furthermore, when the speed of the X axis enters the preset stop judgment width and the vibration of the speed converges within the stop judgment width for a predetermined number of times, the motion completion judgment unit 202 judges that the motion is completed and notifies the interpolation unit 201 of the motion completion confirmation. Upon receiving the notification of the motion completion confirmation, the interpolation unit 201 starts the motion of the next program block.

[0136] In addition, the operation completion determination unit 202 notifies the operation completion confirmation to the machining time prediction unit 500. Upon receiving the operation completion confirmation notification, the machining time prediction unit 500 recognizes the end of the program block and measures the machining time.

[0137] (2) Determining the completion of an action during acceleration or deceleration

[0138] When the speed or the spindle speed is changed, the operation completion determination unit 202 checks whether the speed has been reached and determines that the operation is completed.

[0139] Fig.10 This is a characteristic diagram for explaining the speed reaching width during acceleration and the waiting time until the speed reaches the reaching width.

[0140] The operation completion determination unit 202 sequentially obtains the feed axis speed or spindle speed at time T from the axis operation simulation unit 400 . The operation completion determination unit 202 determines that the operation is completed when the feed axis speed or spindle speed reaches a preset reaching width, and notifies the interpolation unit 201 of the operation completion confirmation.

[0141] In addition, the operation completion determination unit 202 notifies the operation completion confirmation to the machining time prediction unit 500. Upon receiving the operation completion confirmation notification, the machining time prediction unit 500 measures the machining time.

[0142] Even during deceleration, the operation completion determination unit 202 can determine that the operation is completed when the speed of the feed axis or the spindle speed reaches a preset reaching width.

[0143] (Processing time prediction unit 500)

[0144] The machining time prediction unit 500 measures the time required for executing the machining program to predict the machining time.

[0145] For example, as described above, the machining time prediction unit 500 uses the moving distance, moving path, and command speed obtained by the analysis unit 100 to obtain the command time of the machining program, and measures the time required for executing the machining program based on the obtained command time, the control command output from the axis control unit 300 or the action completion judgment unit 202, and the waiting time obtained based on the completion confirmation notification from the action completion judgment unit 202, to predict the machining time.

[0146] The processing time can be calculated by the sum of the command time and the waiting time.

[0147] Fig.11 This 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.

[0148] The method of using the analysis result in the analysis unit 100 to obtain the command time of the machining program can be performed using a known technology, such as the technology related to the machining time prediction device disclosed in Japanese Patent Application Laid-Open No. 2012-093975. Japanese Patent Application Laid-Open No. 2012-093975 describes a machining time prediction device, which includes: an NC instruction interpretation unit that interprets the NC instruction; a segment data generation unit that divides the tool path into small slices, i.e., segments; an intermediate memory that stores the segment data; a speed limit processing unit that obtains the speed in the tangential direction of the 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 uses the sum of the time to move each segment as the tool movement time. The machining time prediction device calculates the time required for the tool to move along the path specified by the NC instruction.

[0149] The method for calculating the waiting time when stopping is, for example, Fig.11 As shown, the waiting time is obtained by taking the difference between time t2 when the operation is determined to be completed by the operation completion determination unit 202 and time t1 when the X-axis command speed becomes "0" (stop). The method of obtaining the waiting time during acceleration can be performed in the same manner.

[0150] When the acceleration and stop commands of the axes are repeatedly issued in the machining program, the machining time prediction unit 500 adds the total command time and the total waiting time (total command time and waiting time) to predict the machining time.

[0151] The time required for the execution of a machining program refers to, for example, the time from when the analysis of the machining program is started to when the last program block of the machining program is judged to be completed. Regarding how to set the timing of the start and completion of the execution of the machining program, in addition to the above example of calculating the machining time by the sum of the command time and the waiting time, several implementation methods can be conceived. In view of the fact that the present invention is completed with a focus on the command time of the axis action and the waiting time for the completion of the action, whether the start of execution is set to any one before the command start time point of the initial axis action, or whether the completion of execution is set to any one after the action completion judgment of the last axis action, it will not have any impact on the main purpose of the invention.

[0152] The configuration of the machining time prediction device 10 has been described above. Next, the machining time prediction operation of the machining time prediction device 10 will be described using a flowchart, taking as an example the case where the acceleration and stop commands of the axes are repeated in the machining program.

[0153] Fig.12 : is a flowchart showing the operation of the machining time prediction device 10 .

[0154] In step S11, the analyzing unit 100 interprets the NC program to obtain the moving distance, moving path, and command speed. Then, the interpolating 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.

[0155] In step S12 , the axis operation simulation unit 400 performs servo control to make the motors driving the feed axis and the main axis follow the position command value or the speed command value and simulates the operation of the machine tool, and outputs virtual results to the operation completion determination unit 202 .

[0156] In step S13 , completion of the operation is determined based on the command output from the interpolation unit 201 and the virtual performance output from the axis operation simulation unit 400 .

[0157] In step S14 , the machining time prediction unit 500 obtains the command time of the machining program using the interpolation data obtained by the interpolation unit 201 , and obtains the waiting time based on the completion confirmation notification from the operation completion determination unit 202 .

[0158] In step S15 , the machining time prediction unit 500 adds the total of the command time and the total of the waiting time (total command time and waiting time) to predict the machining time.

[0159] (Second Embodiment)

[0160] Fig.13 It is a block diagram showing the structure of a machining time prediction device according to a second embodiment of the present disclosure.

[0161] Fig.13 The processing time prediction device 10A shown in FIG. Figure 1 Compared with the machining time prediction device 10 shown in FIG. 1 , 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 separate functions.

[0162] The model setting unit 600 sets 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, the simulation models of the X-axis motion simulation unit 400A and the Z-axis motion simulation unit 400B are Figure 2 In the case of the block diagram representation of the transfer function, set the integral gain k1, proportional gain k2, torque constant K t 、Motor inertia J m 、Mechanical inertia JL Equal constants.

[0163] The feed axis interpolation unit 201A and the spindle command unit 203 can perform operations with reference to virtual results. For example, the spindle command unit 203 refers to the virtual results output from the Z-axis motion simulation unit 400B when performing a circumferential speed constant control in which the rotation speed increases as the machine approaches the center during lathe processing. The feed axis interpolation unit 201A refers to the virtual results output from the spindle motion simulation unit 400C when performing a rigid tapping control in which the spindle and feed axis are interpolated simultaneously to precisely synchronize the rotation of the tool and the movement of its Z-axis.

[0164] (First Modification)

[0165] In a machine tool, a servo control unit of a feed axis is sometimes required to control the feed motion of the feed axis so as to follow the motion of a spindle. For example, this is the case of controlling a synchronous operation (so-called master-slave synchronization method) in which the feed axis moves in a manner to follow the rotation motion of the spindle while taking into account the pitch specified by the tapping program.

[0166] use Fig.14 The following describes the configuration of axis motion simulation in which the feed motion of the feed axis is controlled to follow the motion of the main axis.

[0167] Fig.14 400C. Figure 2 The structure of the spindle motion simulation unit 400C is the same as that shown in FIG. Figure 3 The structures shown are the same.

[0168] like Fig.14 As shown, the rotation speed calculation unit 421 of the spindle motion simulation unit 400C outputs the spindle rotation speed calculation value (which becomes the virtual performance of other axes) 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 spindle rotation speed calculation value, and outputs it to the Z-axis motion simulation unit 400B. Figure 2 The position command P shown c (It becomes the control command of the axis.) The Z-axis control unit 300B integrates the spindle rotation speed calculation value to obtain the spindle rotation amount, and multiplies the spindle rotation amount by the pitch to calculate the feed operation amount of the feed axis following the operation of the spindle.

[0169] (Second Modification)

[0170] In this modification, Fig.13The following describes an example in which the X-axis motion simulation unit 400A and the Z-axis motion simulation unit 400B of the machining time prediction device 10A are connected to the same DC bus.

[0171] Fig.15 1 is a diagram showing a configuration example in which 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 be connected to separate DC buses.

[0172] Fig.15 The axis motion simulation unit shown has a plurality of mechanisms driven by motors.

[0173] 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 table 446. The servo control unit 441 is a servo control model, and the inverter 442, the motor 443, the coupling 444, the ball screw 445, and the table 446 are device models.

[0174] 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 table 456. The servo control unit 451 is a servo control model, and the inverter 452, the motor 453, the coupling 454, the ball screw 455, and the table 456 are device models.

[0175] The servo control unit 441 and the servo control unit 451 are respectively composed of Figure 2 The position loop transfer function 401 and the speed loop transfer function 402 are represented by the motor 443 and the motor 453, respectively. Figure 2 The transfer functions 403 and 404 of the motor are represented by the coupling 444 and the ball screw 445 and the coupling 444 and the ball screw 445 are respectively represented by Figure 2 The transfer function 405 is represented by the working platform 446 and the working platform 456 are respectively represented by Figure 2 The transfer function 406 is represented.

[0176] In addition, when the inverters 442 and 452 are not modeled, the delay element (1 / (T s +1)), or it can be expressed as directly reaching (torque command = motor applied torque).

[0177] The AC voltage supplied from the AC power source 431 is rectified by the rectifier 432, and the rectified voltage is smoothed by the smoothing capacitor 433. The regenerative resistor 434 generates excess regenerative power and the DC bus voltage (bus voltage) V DWhen the bus voltage reaches a predetermined value, the regenerative power is consumed. When the bus voltage reaches a predetermined value, the regenerative transistor 435 becomes conductive, and the power stored in the smoothing capacitor 433 is consumed by the regenerative resistor 434. The DC bus is connected to the inverter 442 and the inverter 452. The DC bus voltage V D Applied to inverter 442 and inverter 452 . Fig.13 The model setting unit 600 shown sets the capacitance value of the smoothing capacitor 433 and the resistance value of the regenerative resistor 434 .

[0178] The DC bus voltage can be calculated from the AC voltage of the AC power source 431 , the capacitance value of the smoothing capacitor 433 , the resistance value of the regenerative resistor 434 , and the like.

[0179] The servo control unit 441 gives a voltage command to the inverter 442 based on 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 based on the position command value or speed command value output from the Z-axis control unit 300B.

[0180] Inverters 442 and 452 respectively convert the DC bus voltage V D PWM (Pulse Width Modulation) calculation or the like is performed to convert electric power so as to apply a voltage command to the motors 443 and 453 , thereby supplying current to the motors 443 and 453 .

[0181] like Fig.16 As shown in the characteristic diagram, the maximum torque Tor of the motor changes according to the rotational speed N.

[0182] The NT characteristics also change according to the DC link voltage. When the DC link voltage decreases, Fig.16 The region R1 shown is narrowed.

[0183] DC link voltage V D The relationship with region R1 is as follows.

[0184] The R1 region is a region where Mathematical Formula 5 (hereinafter referred to as Mathematical Formula 5) holds true. In Mathematical Formula 5, τ LIM is the electrical and mechanical permissible torque of the motor, Kt is the torque constant, and Rm is the winding resistance.

[0185] [Formula 5]

[0186] τ LIM <K t (V D -K t ω m ) / R m

[0187] In region R1, τ max =τ LIM Regarding the migration to region R2, when Mathematical Formula 6 (hereinafter Mathematical Formula 6) holds, it depends on the DC link voltage V D .

[0188] [Mathematical formula 6]

[0189]

[0190] In the R2 region, Mathematical Formula 7 (hereinafter referred to as Mathematical Formula 7) holds true, τ max Still depends on the DC bus voltage V D .

[0191] [Formula 7]

[0192] τ max =K t (V D -K t ω m ) / R m

[0193] In mathematical formula 4, if torsional rigidity, table inertia, and friction are ignored, the angular velocity ω shown in mathematical formula 8 is obtained. m The angular velocity ω shown in mathematical formula 8 m The relationship is obtained using the differential equation shown in Mathematical Formula 1.

[0194] [Mathematical formula 8]

[0195]

[0196] τ in Calculated by speed servo control, but cannot exceed the maximum value τ determined by the NT characteristic max .

[0197] The spindle of a machine tool is often required to accelerate and decelerate between the low rotation area and the high rotation area with maximum torque. max Assuming it is constant, calculate ω using mathematical formula 8 m In comparison, considering the NT characteristics, ω is calculated using mathematical formula 8 m In this case, the prediction accuracy of the speed arrival waiting time will be improved.

[0198] exist Fig.17 In the example, time T1 represents the time when the region R1 is max The waiting time T2 is also applied to the region R2 and is predicted to be the waiting time taking the NT characteristics into consideration.

[0199] According to the above-described embodiments, even when axis stop commands appear frequently in a machining program or when an axis with large inertia is mounted on a machine tool, accurate machining time prediction can be performed without using actual machining data.

[0200] Furthermore, according to each embodiment, if a movement amount or a command point sequence is given to a peripheral axis that is responsible for the operation of an auxiliary mechanism such as an automatic tool changer, the operation time of the peripheral axis can be predicted.

[0201] As described above, in order to realize the functional blocks included in the machining time prediction device in this embodiment, the machining time prediction device can be realized by hardware, software, or a combination thereof. Here, realization by software means realization by a computer reading and executing a program.

[0202] In order to realize the functional blocks included in the machining time prediction device in this embodiment by software or a combination thereof, the machining time prediction device specifically includes a CPU (Central Processing Unit) and other computing devices. In addition, the machining time prediction device also includes an auxiliary storage device such as a HDD (Hard Disk Drive) storing various control programs such as application software or OS (Operating System), and a main storage device such as a RAM (Random Access Memory) for storing data temporarily required when the computing device executes the program.

[0203] Furthermore, in the machining time prediction device, the operation processing device reads the application software or OS from the auxiliary storage device, expands the read application software or OS in the main storage device, and performs operation processing based on the application software or OS. In addition, various hardware included in each device is controlled based on the operation result. In this way, the functional blocks of this embodiment are realized.

[0204] Each component included in the processing time prediction device can be realized by hardware including electronic circuits, etc. In the case where the processing time prediction device is composed of hardware, for example, a part or all of the functions of each component included in the processing time prediction device can be composed of 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).

[0205] The program can be stored using various types of non-transitory computer readable media (non-transitorycomputer readable medium) and provided to the computer. Non-transitory computer readable media include various types of tangible recording media (tangible storage medium). Examples of non-transitory computer readable media include magnetic recording media (e.g., hard disk drives), magneto-optical recording media (e.g., magneto-optical disks), CD-ROMs (Read Only Memory), CD-Rs, CD-R / Ws, semiconductor memories (e.g., mask ROMs, PROMs (Programmable ROMs), EPROMs (Erasable PROMs), flash ROMs, RAMs (random access memory)). In addition, the program can also be provided to the computer via various types of transitory computer readable media (transitory computer readable medium).

[0206] The above-described embodiment is a preferred embodiment of the present invention, but the scope of the present invention is not limited to the above-described embodiment, and the present invention can be implemented in various modified forms without departing from the gist of the present invention.

[0207] The machining time prediction device and machining time prediction method disclosed herein include the above-described embodiments and can take various embodiments having the following structures.

[0208] (1) A machining time prediction device (e.g., machining time prediction device 10, 10A) predicts the machining time of a machine tool that controls at least one axis to machine a workpiece based on a machining program, wherein:

[0209] The processing time prediction device comprises:

[0210] An analyzing unit (e.g., analyzing unit 100) that analyzes the machining program and generates a motion command for the axis;

[0211] an execution control unit (e.g., the execution control unit 200), which includes an interpolation unit (e.g., the interpolation unit 201) for controlling the execution of the motion command and instructing the motion of the axis according to the result of analyzing the machining program, and an motion completion determination unit (e.g., the motion completion determination unit 202) for determining whether the motion of the axis is completed;

[0212] an axis control unit (e.g., axis control unit 300) that generates a control command according to an operation instruction of the axis from the interpolation unit;

[0213] A processing time prediction unit (e.g., processing time prediction unit 500) that measures the time required for executing the processing program and predicts the processing time;

[0214] an axis motion simulation unit (e.g., axis motion simulation unit 400) that simulates the motion of the axis according to the control instruction and outputs a virtual result,

[0215] The operation completion determination unit determines the completion of the operation of the axis based on the virtual performance.

[0216] According to this machining time prediction device, even when axis stop commands appear frequently in a machining program or when an axis with large inertia is mounted on a machine tool, accurate machining time prediction can be performed without using actual machining data.

[0217] (2) The machining time prediction device according to (1) above, wherein the axis operation simulation unit simulates the operation of a feed axis that draws a trajectory based on the machining program and a spindle that rotates a tool or a workpiece.

[0218] (3) The machining time prediction device according to (2) above, wherein the axis motion simulation unit operates to follow the motion of the other axis based on the virtual performance of the other axis.

[0219] (4) A machining time prediction device according to (2) or (3) above, wherein the machining time prediction device is capable of changing, through a machining program command, whether the axis motion simulation performed by the axis motion simulation unit is the feed axis or the spindle.

[0220] (5) A machining time prediction device according to any one of (1) to (4) above, wherein the machining time prediction device comprises: a model setting unit capable of changing the characteristics of the axis motion simulation unit;

[0221] The axis motion simulation unit comprises:

[0222] A servo control model that enables the virtual performance to follow the control instruction;

[0223] The plant model includes a numerical solution of one or more differential equations, and calculates the virtual performance when the operation amount as the output of the servo control model is input.

[0224] (6) The machining time prediction device according to (5) above, wherein the equipment model includes: an electric motor driven by an inverter as a power source for the axis;

[0225] The machining time prediction device is capable of calculating a DC bus voltage connected to the inverter.

[0226] (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 inverter of each axis motion simulation unit is connected to the same DC bus.

[0227] (8) A machining time prediction method, wherein a computer as a machining time prediction device for predicting a machining time of a machine tool that controls at least one axis to machine a workpiece based on a machining program executes the following processing:

[0228] Analyzing the machining program to generate motion commands for the axis;

[0229] The processing of summarizing the execution of the motion command, instructing the motion of the axis according to the result of analyzing the machining program, and judging whether the motion of the axis is completed;

[0230] generating a control instruction according to the axis motion instruction;

[0231] A process of measuring a time required for executing the machining program to predict the machining time;

[0232] Axis motion simulation processing for simulating the motion of the axis according to the control command and outputting a virtual result,

[0233] In the process of determining whether the operation of the axis is completed, the completion of the operation of the axis is determined based on the virtual performance.

[0234] According to this machining time prediction method, even when axis stop commands appear frequently in a machining program or when an axis with large inertia is mounted on a machine tool, accurate machining time prediction can be performed without using actual machining data.

[0235] Description of Reference Numerals

[0236] 10.10A processing time prediction device

[0237] 100 Analysis Department

[0238] 200 Execution Control Department

[0239] 201 Interpolation Department

[0240] 202 Action completion judgment unit

[0241] 300 Axis control unit

[0242] 400 axis motion simulation unit

[0243] 500 Processing Time Prediction Department

[0244] 600 Model Setting Department.

Claims

1. A processing time prediction device, which predicts the processing time of a machine tool that controls at least one axis to process a workpiece according to a processing program, characterized in that: The processing time prediction device comprises: An analyzing unit that analyzes the machining program and generates a motion command for the axis; an execution control unit including an interpolation unit and an action completion judgment unit, wherein the interpolation unit summarizes the execution of the action command and instructs the action of the axis according to the result of analyzing the machining program, and the action completion judgment unit judges whether the action of the axis is completed; an axis control unit that generates a control instruction according to an operation instruction of the axis from the interpolation unit; a machining time prediction unit that calculates the time required for executing the machining program and predicts the machining time; and The axis motion simulation unit simulates feedback control using the servo control model and the device model to calculate the virtual performance of the axis motion. The operation completion determination unit determines the completion of the operation of the axis based on the virtual performance. The machining time prediction unit calculates a time required for executing the machining program based on a command time of the machining program and a waiting time obtained based on completion of the control command and the movement of the axis.

2. The processing time prediction device according to claim 1, characterized in that: The axis motion simulation unit simulates the motion of a feed axis that draws a trajectory based on the machining program and a spindle that rotates a tool or a workpiece.

3. The processing time prediction device according to claim 2, characterized in that: The axis motion simulation unit operates to follow the motion of the other axis based on the virtual performance of the other axis.

4. The processing time prediction device according to claim 2 or 3, characterized in that: The machining time prediction device can change whether the axis motion simulation unit performs the axis motion simulation of the feed axis or the main axis by means of a command of a machining program.

5. The processing time prediction device according to any one of claims 1 to 3, characterized in that: The machining time prediction device comprises: a model setting unit capable of changing the characteristics of the axis motion simulation unit; The plant model includes the numerical solution of one or more differential equations.

6. The processing time prediction device according to claim 4, characterized in that: The machining time prediction device comprises: a model setting unit capable of changing the characteristics of the axis motion simulation unit; The plant model includes the numerical solution of one or more differential equations.

7. The processing time prediction device according to claim 5, characterized in that: The device model includes: an electric motor driven by an inverter as a power source for the shaft, The machining time prediction device is capable of calculating a DC bus voltage connected to the inverter.

8. The processing time prediction device according to claim 7, characterized in that: The axis operation simulation unit is provided for each of two or more axes, and the inverter of each axis operation simulation unit is connected to the same DC bus.

9. A processing time prediction method, characterized in that: A computer as a machining time prediction device for predicting a machining time of a machine tool that controls at least one axis to machine a workpiece based on a machining program executes the following processing: parsing the machining program to generate motion commands for the axis; The processing of summarizing the execution of the motion command, instructing the motion of the axis according to the result of analyzing the machining program, and judging whether the motion of the axis is completed; generating a control instruction according to the axis motion instruction; The processing of calculating the time required for executing the machining program to predict the machining time; as well as According to the control instruction, feedback control is simulated by the servo control model and the device model to calculate the virtual performance of the axis movement. In the process of judging whether the movement of the axis is completed, judging whether the movement of the axis is completed based on the virtual performance, In the process of predicting the machining time, the time required for executing the machining program is calculated based on the command time of the machining program and the waiting time, wherein the waiting time is obtained based on the completion of the control command and the movement of the axis.

Images