Machining simulation device and machining simulation method

Abstract

The present invention provides a machining simulation device that can obtain the transfer function of a machine tool without data collection and professional knowledge. The machining simulation device includes: a transfer characteristic generation unit that generates the transfer characteristics of the machine tool; a simulation execution unit that simulates the behavior of the machine tool using the transfer characteristics. The transfer characteristic generation unit includes: a control information acquisition unit that acquires motor information and control parameters of the motor control system of the machine tool; a motor characteristic calculation unit that calculates the motor characteristics based on the motor information; a control characteristic calculation unit that calculates the control characteristics of the motor control system based on the control parameters; a transfer characteristic calculation unit that calculates transfer characteristics satisfying predetermined requirements based on the motor characteristics and the control characteristics.

Description

Technical Field

[0001] The present disclosure relates to a machining simulation apparatus and a machining simulation method, and more particularly to a machining simulation apparatus and a machining simulation method that simulate the behavior of a machine tool using a transfer function representing the transfer characteristics of the machine tool. Background Art

[0002] Techniques for simulating the behavior of a machine tool using a transfer function representing the transfer characteristics of the machine tool are described in Patent Documents 1 to 4.

[0003] Patent Document 1 describes a numerical control method that enables machining to be performed in a short time without causing damage to the machined surface even when the commanded path includes errors.

[0004] Specifically, Patent Document 1 describes the following: The numerical control method predicts the trajectory of a machining tool when the speed control of the machine tool is performed based on the commanded path and the commanded feed rate indicated by the machining program according to the transfer characteristics from the commanded position to the machining position, and obtains the allowable feed rate based on a characteristic quantity representing the time change of the position of the machining tool on the predicted trajectory and its allowable value. The characteristic quantity uses the acceleration of the machining tool on the predicted trajectory or the normal component of the acceleration, etc.

[0005] Patent Document 2 describes a machining simulation apparatus that prevents the occurrence of chatter caused by resonance and realizes an improvement in surface accuracy and the like.

[0006] Specifically, Patent Document 2 describes the following: The machining simulation apparatus performs a machining simulation on graphic data before machining. The machining simulation unit simulates the frequency of forced vibration and / or the frequency of load variation caused by interrupted cutting based on the machining information, and based on the obtained frequency, the numerical control instruction generation unit generates a numerical control instruction. It is also described that with the machining simulation apparatus, the spindle rotation speed can be reflected in the actual machining or the machining program generation under conditions suitable for actual machining, so that the frequency of forced vibration and / or the frequency of load variation caused by interrupted cutting or the high-order harmonic frequencies that are integer multiples thereof do not become close to the natural vibration frequencies of the machine, tool, fixture, or workpiece, etc., and the occurrence of chatter caused by resonance can be prevented.

[0007] Patent Document 3 describes a machining method for obtaining correction data in a short time.

[0008] Specifically, Patent Document 3 describes a machining method for machining a non-circular workpiece. Among them, in the first step, the contour data of the non-circular workpiece is divided into data for the workpiece main shaft and the tool feed shaft, and Fourier transform is performed on each data to calculate the gain and phase at each frequency; in the second step, according to the transfer functions of the main shaft device and the tool feed shaft device for machining the contour shape, the gain and phase at each frequency are calculated; in the third step, for the workpiece main shaft and the tool feed shaft, the gain and phase at each frequency obtained in the second step are added to the gain and phase at each frequency obtained in the first step; in the fourth step, inverse Fourier transform is performed on the frequency data of the workpiece main shaft and the tool feed shaft of the non-circular workpiece obtained in the third step; in the fifth step, machining data for the workpiece main shaft and the tool feed shaft of the non-circular workpiece obtained in the fourth step, that is, correction data, is produced; based on the correction data, machining of the non-circular workpiece is performed.

[0009] Patent Document 4 describes a machining simulation device for a machine tool that can suppress an increase in time and perform machining simulation with high precision.

[0010] Specifically, Patent Document 4 describes a machining simulation device that performs machining simulation of a machine tool that machines a machining object using a tool based on a machining program. Among them, the machining simulation device includes: a mechanical simulation unit that, based on a position command and the transfer characteristics of the machine tool, performs simulation of the operation of the machine tool when operating based on the machining program, thereby estimating the position of the tool; and a machining simulation unit that, based on the information of the tool and the estimated position of the tool, performs machining simulation of the machining object.

[0011] Prior Art Documents

[0012] Patent Documents

[0013] Patent Document 1: Japanese Patent Laid-Open No. 2001-051708

[0014] Patent Document 2: International Publication No. 2002 / 003155

[0015] Patent Document 3: Japanese Patent Laid-Open No. 2002-278609

[0016] Patent Document 4: Japanese Patent Laid-Open No. 2019-152936 Summary of the Invention

[0017] Problems to be Solved by the Invention

[0018] In order to perform machining simulation, when obtaining the transfer function of a machine tool, it is required to perform a data collection operation accompanying the trial operation of the machine tool and professional knowledge for analyzing the collected data and calculating the transfer characteristics.

[0019] Therefore, it is desirable to obtain the transfer function of a machine tool without the need for data collection during the trial operation of the machine tool and expertise for calculating transfer characteristics.

[0020] Means for Solving the Problem

[0021] A representative first aspect of the present disclosure is a machining simulation device including:

[0022] A transfer characteristic generation unit that generates transfer characteristics of a machine tool;

[0023] A simulation execution unit that simulates the behavior of the machine tool using the transfer characteristics,

[0024] The transfer characteristic generation unit includes:

[0025] A control information acquisition unit that acquires control information including motor information of the machine tool and control parameters of a motor control system of the machine tool from a storage unit;

[0026] A motor characteristic calculation unit that calculates motor characteristics based on the motor information;

[0027] A control characteristic calculation unit that calculates control characteristics of the motor control system based on the control parameters; and

[0028] A transfer characteristic calculation unit that calculates the transfer characteristics satisfying predetermined requirements based on the motor characteristics and the control characteristics,

[0029] The predetermined requirements include at least one of a response frequency of position control, a response frequency of speed control, a natural vibration frequency of the machine tool, and a resonance frequency between a driving unit and a driven unit in the machine tool.

[0030] A representative second aspect of the present disclosure is a machining simulation method, in which a computer executes the following processes:

[0031] A process of calculating motor characteristics based on motor information of a machine tool;

[0032] A process of calculating control characteristics of the motor control system based on control parameters of the motor control system of the machine tool;

[0033] A process of calculating transfer characteristics satisfying predetermined requirements based on the motor characteristics and the control characteristics; and

[0034] A process of simulating the behavior of the machine tool using the transfer characteristics,

[0035] The predetermined requirements include at least one of a response frequency of position control, a response frequency of speed control, a natural vibration frequency of the machine tool, and a resonance frequency between a driving unit and a driven unit in the machine tool. Brief Description of the Drawings

[0036] Figure 1 It is a structural diagram showing a structural example of a machining simulation system of a machine tool according to an embodiment of the present invention.

[0037] Figure 2 It is a diagram showing the driving part and the driven part of the machine tool represented by a rigid body model.

[0038] Figure 3 It is a diagram showing the driving part and the driven part of the machine tool represented by a two-inertia system model.

[0039] Figure 4 It is a block diagram showing the structure of a position control loop when a motor control system, a driving part, and a driven part form a position control loop.

[0040] Figure 5 It is a block diagram showing the structure of a simplified position control loop.

[0041] Figure 6 It is a block diagram showing the structure of a speed control loop when a motor control system, a driving part, and a driven part form a speed control loop.

[0042] Figure 7 It is a characteristic diagram schematically showing the frequency response gain of a transfer function.

[0043] Figure 8 It is a characteristic diagram showing an example of the frequency response gain of speed PI control.

[0044] Figure 9 It is a characteristic diagram showing an example of the frequency response gain of speed P control.

[0045] Figure 10 It is a diagram showing an example of a user interface displayed on a display screen of a display device of a personal computer.

[0046] Figure 11 It is a flowchart showing the operation of the machining simulation device. Detailed Description of the Embodiment

[0047] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings.

[0048] Figure 1 It is a structural diagram showing a structural example of a machining simulation system of a machine tool according to an embodiment of the present invention.

[0049] As Figure 1 shown, the machining simulation system 10 of the machine tool includes a control device 100 of the machine tool and a machining simulation device 200.

[0050] The control device 100 of the machine tool controls the movement of the feed axis, the rotation of the spindle, etc. of the machine tool according to the machining program. The control device 100 has a motor that serves as the driving part of the machine tool, a driven part, and a motor control system that controls the motor. The control device 100 stores the motor information of the machine tool and the control parameters of the motor control system in the storage unit 101. The motor information and control parameters will be described later. The motor information and control parameters of the machine tool can also be stored in a storage unit separately provided from the control device 100. The storage unit can also be provided in the machining simulation device 200. When the storage unit is separately provided from the control device 100, the machining simulation system 10 may not include the control device 100 of the machine tool.

[0051] The machining simulation device 200 includes a transfer characteristic generation unit 210 and a simulation execution unit 220. The transfer characteristic generation unit 210 calculates the transfer function of the machine tool using the motor information and control parameters obtained from the storage unit 101 of the control device 100 of the machine tool. The simulation execution unit 220 uses the calculated transfer function to simulate the control of the control device 100 of the machine tool based on the machining program, the behavior of the motor as the driving part and the driven part, and the feedback control of the control device 100 based on the position information of the driving part and the driven part (for example, the position control loop as described later Figure 4 ), and outputs the position information of each axis as the simulation result.

[0052] The transfer characteristic generation unit 210 includes a control information acquisition unit 211, a motor characteristic calculation unit 212, a control characteristic calculation unit 213, and a transfer characteristic calculation unit 214.

[0053] Hereinafter, each structure of the transfer characteristic generation unit 210 will be described.

[0054] (Control Information Acquisition Unit 211)

[0055] The control information acquisition unit 211 acquires control information including motor information and control parameters from the storage unit 101 of the control device 100 of the machine tool. The motor information is, for example, based on at least one of the motor inertia (also referred to as motor inertia), inertia ratio, and spring constant of the motor. The inertia ratio represents the load inertia / motor inertia. The load inertia is also referred to as load inertia. The motor inertia sometimes includes the inertia of the reducer and the ball screw. The control parameters are, for example, the position control proportional gain K P of the position control unit included in the motor control system of the control device 100, V and the speed loop gain K 1 of the speed control unit, the speed control integral gain K 2 of the speed control unit, and at least one of the speed control proportional gain K of the speed control unit.

[0056] The storage unit 101 may also store the motor inertia as part of a specification or a motor characteristic database. In this case, the control information acquisition unit 211 acquires information capable of identifying the motor, such as the model number of the motor, from the storage unit 101, and acquires the motor inertia by referring to the specification or the motor characteristic database.

[0057] (Motor characteristic calculation unit 212)

[0058] The motor characteristic calculation unit 212 calculates the motor characteristics based on the motor information.

[0059] If the rigid body system model shown in Figure 2 represents the motor of the driving unit and the mechanical model of the driven unit of the machine tool, then when the motor information is the motor inertia J M and the inertia ratio R, the motor characteristic M 1 is represented by the transfer function of Mathematical Formula 1 (the following Mathematical Formula 1). s is the variable of the Laplace transform.

[0060] [Mathematical Formula 1]

[0061]

[0062] If the two-inertia system model shown in Figure 3 represents the motor of the driving unit and the mechanical model of the driven unit of the machine tool, then when the motor information is the motor inertia J M , the natural vibration frequency ω O , and the resonance frequency ω P , the motor characteristic M 2 is represented by the transfer function of Mathematical Formula 2 (the following Mathematical Formula 2).

[0063] [Mathematical Formula 2]

[0064]

[0065] The natural vibration frequency ω O and the resonance frequency ω P in Mathematical Formula 2 are obtained using the motor inertia J M , the inertia ratio R, and the spring constant K S of the spring element between the motor inertia and the load inertia, by Mathematical Formula 3 (the following Mathematical Formula 3).

[0066] [Mathematical Formula 3]

[0067]

[0068] The natural vibration frequency ω Ois the natural vibration frequency of the free vibration of the driven part when the fixed driving part, and is sometimes called the anti-resonance frequency. The resonance frequency ω of the double-inertia system model P is the frequency at which the driving part and the driven part vibrate in antiphase.

[0069] Regarding the transfer function that combines the motor inertia and the load inertia with a spring element, it is described, for example, in "Research on Low-Frequency Vibration Suppression Control Based on the Double-Inertia System Model for the Feed Axis of NC Machine Tools", Heisuke Iwashi, et al., Transactions of the Japan Society for Precision Engineering, Vol. 82, No. 8, 2016.

[0070] (Control characteristic calculation unit 213)

[0071] The control characteristic calculation unit 213 calculates the control characteristics of the motor control system based on the control parameters.

[0072] In the case where the motor control system included in the control device 100, and the driving part and the driven part form a position control loop, the position control loop is composed of Figure 4 The block diagram is shown. As Figure 4 shown, the position control loop can be represented by the position control unit 111, the speed control unit 112, the mechanical model unit 113 composed of the driving part and the driven part, and the integrator 114. As Figure 4 shown, the position control loop is mostly composed of a double loop with a speed control loop inside. In Figure 4 , y’ represents the position command, y represents the position actual value, r represents the speed command, u represents the operation amount, and w represents the speed actual value. The operation amount u is, for example, a torque command, but in a servo motor, via the torque constant K T , torque = K T × current, so the operation amount u can also be set as the current.

[0073] The response frequency of the position control loop has to be lower than the response frequency of the speed control loop located inside. Therefore, for simplicity, in the structure of the block diagram shown in Figure 4 , the closed-loop transfer function from the speed command r to the speed actual value w is regarded as 1, and it can be processed as the structure of the block diagram shown in Figure 5 .

[0074] When the position control loop is the structure of the block diagram shown in Figure 5 , the position control loop is composed of the position control unit 111 and the integrator 114, and the motor control system corresponds to the position control unit 111. The control characteristic C P of the position control unit 111 that becomes the motor control system is represented by C P = K P , and the control parameter is the position control proportional gain K P .

[0075] When the motor control system included in the control device 100 and the drive unit and the driven unit form a speed control loop, the speed control loop is as shown in the block diagram of Figure 6 . The speed control loop can be represented by a speed control unit 112 and a mechanical model unit 113 composed of a drive unit and a driven unit. The speed control unit 112 corresponds to the motor control system.

[0076] In the case of speed PI control, the control characteristic C of the speed control unit 112 that is the motor control system V is represented by Mathematical Formula 4 (the following Mathematical Formula 4). In Mathematical Formula 4, K V is the speed loop gain, K 1 is the speed control integral gain, and K 2 is the speed control proportional gain. The control parameters are the speed loop gain K V , the speed control integral gain K 1 , and the speed control proportional gain K 2 .

[0077] [Mathematical Formula 4]

[0078]

[0079] In the case of speed P control, the control characteristic C of the speed control unit is V obtained by setting K 1 = 0 and K 2 = 1 in Mathematical Formula 4, and becomes C V = K V . The control parameter is the speed loop gain K V .

[0080] (Transfer Characteristic Calculation Unit 214)

[0081] The transfer characteristic calculation unit 214 changes at least one of the motor characteristics calculated by the motor characteristic calculation unit 212 and the control characteristics calculated by the control characteristic calculation unit 213 to calculate the transfer characteristics of the machine tool so as to satisfy a predetermined requirement. The predetermined requirement is at least one of the response frequency of position control, the response frequency of speed control, the natural vibration frequency of the machine tool, and the resonance frequency between the drive unit and the driven unit in the machine tool. The predetermined requirement will be described later. The value of the predetermined requirement can be given by the user or obtained by the transfer characteristic calculation unit 214 from the storage unit 101 of the control device 100, a storage unit provided outside the control device 100, or a storage unit provided inside the machining simulation device.

[0082] First, the transfer characteristics of the machine tool will be described.

[0083] The transfer function G of the closed loopC Use the open-loop transfer function G O , and represent it with G C = G O / (1 + G O ).

[0084] The transfer characteristic calculation unit 214 obtains the closed-loop transfer function G PC (s) of the position control loop and the closed-loop transfer function G VC (s) of the speed control loop as follows.

[0085] Since Figure 5 the open-loop transfer function G PO (s) of the position control loop shown is G PO (s) = K P / s, the closed-loop transfer function G PC (s) of the position control loop is represented by Mathematical Formula 5 (the following Mathematical Formula 5).

[0086] [Mathematical Formula 5]

[0087]

[0088] Regarding the closed-loop transfer function G VC (s) of the speed control loop, in the case of speed PI control, the open-loop transfer function G VO (s) is represented by Mathematical Formula 6 (the following Mathematical Formula 6), and thus is represented by Mathematical Formula 7 (the following Mathematical Formula 7). In Mathematical Formula 6 and Mathematical Formula 7, M represents the motor characteristic. When the mechanical model is represented by a rigid body system model, M = M 1 , and when the mechanical model is represented by a two-inertia system model, M = M 2 .

[0089] [Mathematical Formula 6]

[0090]

[0091] [Mathematical Formula 7]

[0092]

[0093] The closed-loop transfer function G VC (s) of the speed control loop in the case of speed P control is obtained by setting K 1 = 0 and K 2 = 1 in Mathematical Formula 7, and is represented by Mathematical Formula 8 (the following Mathematical Formula 8).

[0094] [Mathematical Formula 8]

[0095]

[0096] Next, the predetermined requirements will be described.

[0097] (In the case where the predetermined requirement is the response frequency of position control)

[0098] If the transfer function is a rational function of s, when the command a is a sine wave of frequency ω, the control quantity b also becomes a sine wave of frequency ω. At this time, the amplitude ratio of the command a to the control quantity b is called the frequency response gain at frequency ω. The frequency response gain of the closed-loop transfer function G C (s) can be calculated by substituting s with jω through Mathematical Formula 9 (the following Mathematical Formula 9). The unit is decibel (dB).

[0099] [Mathematical Formula 9]

[0100] 20log|G C (jω)|

[0101] Generally, the frequency response gain of the closed-loop transfer function indicates around 0 dB when the frequency response gain of the open-loop transfer function is 0 dB or more. The frequency response gain of the closed-loop transfer function being around 0 dB (amplitude ratio 1) indicates that the control quantity b follows the command a.

[0102] Therefore, the frequency at which the frequency response gain of the closed-loop transfer function intersects or becomes maximum with 0 dB - 3 dB (amplitude ratio 1 / √2) is called the response frequency of control.

[0103] In addition, the frequency at which the frequency response gain of the open-loop transfer function intersects 0 dB is called the response frequency of control.

[0104] If s in the transfer function G PC (s) of Mathematical Formula 5 is substituted with jω, then Mathematical Formula 10 (the following Mathematical Formula 10) is obtained, and ω = K at which 20log|G(jω)| = -3 dB P becomes the response frequency of position control.

[0105] [Mathematical Formula 10]

[0106]

[0107] (In the case where the predetermined requirement is the response frequency of speed control)

[0108] When the control characteristic C is speed P control and the motor characteristic M is a double-inertia system model, the open-loop transfer function of the speed control loop is represented by Mathematical Formula 11 (the following Mathematical Formula 11).

[0109] [Mathematical Formula 11]

[0110]

[0111] The frequency response gain of the transfer function of Mathematical Expression 11 is schematically shown by Figure 7 the gain line graph of. In Figure 7 it, the horizontal axis is a logarithmic scale of frequency.

[0112] The position where the frequency response gain intersects with 0 dB is the response frequency, the position where the minimum value of the frequency response gain is taken is the natural vibration frequency, and the position where the maximum value of the frequency response gain is taken is the resonance frequency.

[0113] As Figure 7 shown, the frequency values are generally resonance frequency > natural vibration frequency > response frequency of speed control. This relationship is the same in the case of speed PI control. When the frequency ω is below the response frequency of speed control, it becomes resonance frequency ω P > natural vibration frequency ω O > frequency ω (ω P > ω O > ω), becoming ω P 2 > ω O 2 > ω 2 , so the s in Mathematical Expression 2 can be ignored 2 for consideration. If s is ignored 2 , then Mathematical Expression 2 is equal to Mathematical Expression 1. That is, when considering the response frequency of speed control, Mathematical Expression 1 representing the rigid body system model can be used as the motor characteristic M.

[0114] <Case of speed PI control>

[0115] As the control characteristic C, considering the case of speed PI control, when using the rigid body system model as the motor characteristic M, Mathematical Expression 7 is as shown in Mathematical Expression 12 (the following Mathematical Expression 12).

[0116] [Mathematical Expression 12]

[0117]

[0118] When s in Mathematical Expression 12 is replaced with jω, Mathematical Expression 12 is as shown in Mathematical Expression 13 (the following Mathematical Expression 13).

[0119] [Mathematical Expression 13]

[0120]

[0121] Using Mathematical Expression 13, the frequency response gain is expressed as in Mathematical Expression 14 (the following Mathematical Expression 14).

[0122] [Mathematical Expression 14]

[0123]

[0124] In Mathematical Expression 14, until the value of Mathematical Expression 15 (the following Mathematical Expression 15) where the absolute value of the denominator is equal to the absolute value of the numerator, the frequency response gain is 0 dB or more. Therefore, the value ω of Mathematical Expression 15 is used as the response frequency of the speed PI control.

[0125] [Mathematical Expression 15]

[0126]

[0127] Figure 8 is a characteristic diagram showing an example of the frequency response gain of the speed PI control.

[0128] <Case of speed P control>

[0129] Considering the case of speed P control as control characteristic C, when using a rigid body system model as the motor characteristic M, in Mathematical Expression 14, let K 1 = 0, K 2 = 1, the frequency response gain is as shown in Mathematical Expression 16 (the following Mathematical Expression 16).

[0130] [Mathematical Expression 16]

[0131]

[0132] In Mathematical Expression 16, the value ω of Mathematical Expression 17 (the following Mathematical Expression 17) where 20log|G(jω)| = -3 dB is used as the response frequency of the speed P control.

[0133] [Mathematical Expression 17]

[0134]

[0135] Figure 9 is a characteristic diagram showing an example of the frequency response gain of the speed P control.

[0136] (When the predetermined requirement is the natural vibration frequency or resonance frequency of the machine tool)

[0137] As described above, if Figure 3 is used to represent the motor and the driven part that are the drive part of the machine tool with the double-inertia system model shown, when the motor information is the motor inertia J M , the natural vibration frequency ω O , the resonance frequency ω P , the motor characteristic M 2 is represented by Mathematical Expression 2. The natural vibration frequency ω O , the resonance frequency ω P in Mathematical Expression 2 uses the motor inertia J M, inertia ratio R, and spring constant K of the spring element between the motor inertia and the load inertia S , which is represented by mathematical formula 3. These natural vibration frequencies ω O , resonance frequencies ω P become the natural vibration frequencies and resonance frequencies of the machine tool.

[0138] Hereinafter, a method for the transfer characteristic calculation unit 214 to calculate the transfer characteristics of a machine tool that satisfies predetermined requirements will be described.

[0139] The transfer characteristic generation unit 210 included in the machining simulation device 200 has Figure 10 the user interface shown as an application software for a personal computer.

[0140] Figure 10 is a diagram showing an example of displaying the user interface on the display screen of the display device of the personal computer.

[0141] As Figure 10 shown, values of control information obtained from the control information acquisition unit 211 are displayed on the display screen, such as the position control proportional gain K P , speed loop gain K V , speed control integral gain K 1 , speed control proportional gain K 2 and other control parameters, as well as motor inertia J M , inertia ratio R, spring constant K S and other motor information. Specifically, as Figure 10 shown, the position control proportional gain K P is displayed as 30 on the display screen, the speed loop gain K V is displayed as 1, the speed control integral gain K 1 is displayed as 1089, the speed control proportional gain K 2 is displayed as 10.164, the motor inertia J M is displayed as 0.022 [kgm 2 , the inertia ratio R is displayed as 1.2, and the spring constant K S is displayed as 6878 [Nm]. These control parameters and motor information are changed based on predetermined requirements input by the user.

[0142] A region for selecting an object axis for which a model is to be generated from among multiple axes of the machine tool is displayed on the left side of the screen.

[0143] The user sets predetermined requirements through an input form (not shown). For example, in Figure 10 it is shown as "Response frequency of speed control: target 50 Hz" as the setting result in the input form, and the dashed line in the graph represents 50 Hz.

[0144] The user presses Figure 10 the reflection button shown in the figure, and the transfer characteristic calculation unit 214 changes the control characteristic or the motor characteristic according to a predetermined requirement, and provides the generated transfer characteristic to the simulation execution unit 220. The details of the operation of changing the control characteristic or the motor characteristic according to a predetermined requirement will be described later.

[0145] The frequency response of the open-loop transfer function obtained from the result read from the control information is displayed on the display screen. When the user presses the reflection button, the transfer characteristic calculation unit 214 changes the control characteristic or the motor characteristic according to a predetermined requirement. When the transfer function is generated, the frequency response is rewritten according to the generated transfer characteristic. Instead of rewriting the frequency response, the frequency response based on the generated transfer characteristic can also be overlaid and depicted. In addition, the frequency response can be based on the transfer function G C (s) considering feedback.

[0146] In addition, the timing at which the transfer characteristic calculation unit 214 changes the control characteristic or the motor characteristic, or changes the display of the frequency response, may not be when the reflection button is pressed. For example, it may also be the timing when the user changes a predetermined requirement through an input form.

[0147] Figure 10 The numerical values shown in may sometimes be rounded to an appropriate number of decimal places for display, but the number of digits has no particular meaning and is not particularly limited.

[0148] In addition, in Figure 10 it is assumed that the motor is a rotary motor, and the unit of motor inertia is set to inertia [kgm 2 , but in the case of using a linear motor, the unit of inertia can also be set to mass [kg]. The spring constant is also assumed to be a torsion spring and is set to the unit [Nm], but in the case of using a telescopic spring, it can also be set to the unit [N / m].

[0149] The natural vibration frequency ω shown in Mathematical Formula 3 O and the resonance frequency ω P , the frequency ω shown in Mathematical Formula 10, the frequency ω shown in Mathematical Formula 15, and the frequency ω shown in Mathematical Formula 16, etc. are angular frequencies [rad / s]. On the other hand, as Figure 10 the unit of the frequency exemplified for the screen display and the predetermined requirement is set to Hz, but these units can also be rad / s.

[0150] The following describes an example of the operation in which the transfer characteristic calculation unit 214 changes the control characteristic or the motor characteristic according to a predetermined requirement in order to calculate the transfer characteristic of a machine tool that satisfies a predetermined requirement.

[0151] (1) Change the position control proportional gain K PExample of "response frequency of position control" that meets the predetermined requirements

[0152] When the user specifies 10 Hz as the response frequency of position control, if the frequency 10 Hz is expressed in angular frequency, it becomes 10 × 2π (rad / s) = 62.832 (rad / s). As described in Mathematical Formula 10, since the position control proportional gain K P is equal to the response frequency of position control, the position control proportional gain K P is set to K P = 10 × 2π = 62.832.

[0153] The position control proportional gain K P that becomes the control characteristic C P changes from Figure 10 30 shown to 62.832 to meet the "response frequency of position control" that meets the predetermined requirements.

[0154] (2) Example of changing the speed loop gain K V Example of meeting the predetermined requirement "response frequency of speed control" (in the case of speed PI control)

[0155] Change the left side of Mathematical Formula 15 to fc [Hz] and set it as Mathematical Formula 18 (the following Mathematical Formula 18).

[0156] [Mathematical Formula 18]

[0157]

[0158] In Mathematical Formula 18, the motor inertia J M is not changed. Generally, in PI control, the speed control integral gain K 1 and the speed control proportional gain K 2 are adjusted in balance, but here the speed control integral gain K 1 is not changed. Regarding which of the remaining speed loop gain K V and the inertia ratio R to change, the user can, according to the detailed setting items not shown in Figure 10 , change only either one, or can preferentially change either one within the allowable range according to the detailed setting items. In the case where the predetermined requirements cannot be met within the allowable range, change the other one.

[0159] In this example, the following describes an example of meeting the response frequency of speed control of 50 Hz that meets the predetermined requirements by changing only the speed loop gain K V . Solve Mathematical Formula 18 for the speed loop gain K V , and obtain the speed loop gain K V through Mathematical Formula 19 (the following Mathematical Formula 19).

[0160] [Mathematical formula 19]

[0161]

[0162] In this way, the control characteristic C V of the speed loop gain K V is changed from 1 to 2.191, and the control characteristic C V is changed in order to satisfy the "response frequency of speed control" that becomes a predetermined requirement.

[0163] (3) Changing the speed loop gain K V An example of satisfying the predetermined requirement "response frequency of speed control" (in the case of speed P control)

[0164] Change the left side of Mathematical formula 17 to fc [Hz] and set it as Mathematical formula 20 (the following Mathematical formula 20).

[0165] [Mathematical formula 20]

[0166]

[0167] In Mathematical formula 20, the motor inertia J M is not changed. In this example, first, study the case of satisfying the "response frequency of speed control" of 50 Hz, which becomes a predetermined requirement, by changing the inertia ratio R. Solve Mathematical formula 20 for the inertia ratio R, and obtain the inertia ratio R through Mathematical formula 21 (the following Mathematical formula 21).

[0168] [Mathematical formula 21]

[0169]

[0170] The inertia ratio R can be 0 when there is no load inertia, but it cannot be negative. Therefore, if R = 0, solve Mathematical formula 20 for K V then the speed loop gain K V becomes Mathematical formula 22 (the following Mathematical formula 22).

[0171] [Mathematical formula 22]

[0172] K V = 2πf C J M = 2π × 50 × 0.022 = 6.912

[0173] In this way, in order to satisfy the "response frequency of speed control" that becomes a predetermined requirement, the inertia ratio R of the motor characteristic M 1 is changed from 1.2 to 0, and the speed loop gain K of the control characteristic C V V ​Change from 1 to 6.912, thereby changing the motor characteristic M 1 and the control characteristic C V .

[0174] (4) Change the spring constant K S An example of changing the spring constant K to satisfy the predetermined requirement "natural vibration frequency of the machine tool" S Solve the natural vibration frequency ω shown in Mathematical Formula 3 O , and obtain Mathematical Formula 23 (the following Mathematical Formula 23).

[0175] [Mathematical Formula 23]

[0176] K S = RJ M ω O 2

[0177] When the predetermined requirement is a natural vibration frequency of 45 Hz, the spring constant K shown in Mathematical Formula 24 (the following Mathematical Formula 24) is obtained through Mathematical Formula 23 S .

[0178] [Mathematical Formula 24]

[0179] K S = RJ M ω O 2 = 1.2 × 0.022 × (2 × π × 45) 2 = 2111 [Nm]

[0180] In this way, change the spring constant K of the motor characteristic S from Figure 10 6878 [Nm] shown to 2111 [Nm], and change the motor characteristic M 2 in order to satisfy the "natural vibration frequency of the machine tool" that becomes the predetermined requirement.

[0181] (5) Change the spring constant K S An example of changing the spring constant K to satisfy the predetermined requirement "resonance frequency of the driving part and the driven part in the machine tool"

[0182] for the spring constant K S Solve the resonance frequency ω shown in Mathematical Formula 3 P , and obtain Mathematical Formula 25 (the following Mathematical Formula 25).

[0183] [Mathematical Formula 25]

[0184]

[0185] When the predetermined requirement is a resonance frequency of 80 Hz, the spring constant K shown in Mathematical Formula 26 (the following Mathematical Formula 26) is obtained through Mathematical Formula 25 S .

[0186] [Mathematical Formula 26]

[0187]

[0188] In this way, the spring constant K that is a motor characteristic S is changed from Figure 10 6878 [Nm] shown to 3032 [Nm], and the motor characteristic M is changed 2 so as to satisfy the "resonance frequency of the machine tool" that is a predetermined requirement.

[0189] In the above examples (4) and (5), examples of changing the spring constant K S were described, but the inertia ratio R can also be changed. Regarding which of the spring constant K S and the inertia ratio R to change, the user can, according to Figure 10 detailed setting items not shown in the figure, change only either one, or can preferentially change either one within the allowable range according to the detailed setting items. In the case where the predetermined requirement cannot be satisfied within the allowable range, the other one is changed.

[0190] The transfer characteristic calculation unit 214 can change at least one of the motor inertia, inertia ratio, spring constant, position control proportional gain, speed loop gain, speed control integral gain, and speed control proportional gain so that the transfer characteristic satisfies the predetermined requirement. When a rigid body system model considering the load inertia is not used as the motor characteristic (R = 0), the transfer characteristic calculation unit 214 can use a rigid body system model obtained by adding the load inertia to the motor inertia so that the transfer characteristic satisfies the predetermined requirement. In addition, when a rigid body system model is used as the motor characteristic, the transfer characteristic calculation unit 214 can use a two-inertia system model in which the motor inertia and the load inertia are combined through a spring element so that the transfer characteristic satisfies the predetermined requirement.

[0191] In the embodiment described above, higher-precision simulation results can be expected for the control characteristic and the motor characteristic by considering more elements. For example, in academic literature, a damper (attenuation) is considered when initially deriving the two-inertia system model.

[0192] However, even if the simulation execution unit takes into account the damper or nonlinearity, the damper or nonlinearity can be ignored in the calculation of the control characteristics or motor characteristics changed by the transfer characteristic calculation unit. This is because the damper and nonlinearity have low sensitivity to frequency characteristics such as response frequency, natural frequency, and resonance frequency compared to the control gain, inertia ratio, and spring constant.

[0193] The above has described each structure of the machining simulation device 200.

[0194] Next, a machining simulation method will be described. In the following description, an example of executing the machining simulation method using the machining simulation device 200 will be described, but it can also be executed in a device other than the machining simulation device 200.

[0195] Figure 11 It is a flowchart showing the operation of the machining simulation device.

[0196] In step S1, the control information acquisition unit 211 acquires control information including motor information and control parameters. The motor information is, for example, based on at least one of the motor inertia, inertia ratio, and spring constant of the motor. The control parameter is, for example, the position control proportional gain K of the position control unit included in the motor control system of the control device 100 P , the speed loop gain K V , the speed control integral gain K of the speed control unit 1 , and the speed control proportional gain K of the speed control unit 2 or at least one of them.

[0197] In step S2, the motor characteristic calculation unit 212 calculates the motor characteristics based on the motor information.

[0198] In step S3, the control characteristic calculation unit 213 calculates the control characteristics of the motor control system based on the control parameters. Step S3 can be performed before step S2 or in parallel with step S2.

[0199] In step S4, the transfer characteristic calculation unit 214 determines whether a predetermined requirement is input. If it is input, it transfers to step S5; if not, it transfers to step S6.

[0200] In step S5, the transfer characteristic calculation unit 214 changes at least one of the motor characteristics calculated by the motor characteristic calculation unit 212 and the control characteristics calculated by the control characteristic calculation unit 213 so as to satisfy the input predetermined requirement.

[0201] In step S6, when at least one of the motor characteristics and the control characteristics is changed in step S5, the transfer characteristic calculation unit 214 calculates the transfer characteristics of the machine tool based on at least one of the changed motor characteristics and control characteristics. When the predetermined requirements are not input in step S4, the transfer characteristic calculation unit 214 calculates the transfer characteristics of the machine tool based on at least one of the motor characteristics calculated by the motor characteristic calculation unit 212 and the control characteristics calculated by the control characteristic calculation unit 213.

[0202] In step S7, the simulation execution unit 220 uses the calculated transfer function to simulate the control of the control device 100 of the machine tool based on the machining program, the behavior of the motor as the driving unit and the driven unit, and the feedback control of the control device 100 based on the position information of the driving unit and the driven unit, and outputs the position information of each axis as the simulation result.

[0203] The structural parts included in the machining simulation device of the embodiment described above can be implemented by hardware, software, or a combination thereof. Here, implementing by software means implementing by a computer reading and executing a program.

[0204] In order to implement the structural parts included in the machining simulation device by software or a combination thereof, the machining simulation device includes a processor such as a CPU (Central Processing Unit). The processor functions as an execution unit. The machining simulation device may also include multiple processors that operate in parallel. In addition, the machining simulation device further includes an auxiliary storage device such as an HDD (Hard Disk Drive) that stores various programs such as application software or an OS (Operating System), and a main storage device such as a RAM (Random Access Memory) for storing the programs required for the processor to execute the functions and operations of the machining simulation device described above Figure 1 、 Figure 6 and the data temporarily required in the program. The machining simulation device may also include multiple main storage devices.

[0205] Then, in the machining simulation device, the processor 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 based on these application software or OS. In addition, based on the operation result, various hardware included in the machining simulation device is controlled. Thus, the functional blocks of the present embodiment are realized.

[0206] The structural parts included in the machining simulation device can be implemented by hardware including electronic circuits, etc. When the machining simulation device is constituted by hardware, for example, each structural part included in the machining simulation 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.

[0207] The program can be stored using various types of non-transitory computer-readable media and provided to the 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-ROMs (read-only memories), CD-Rs, CD-R / Ws, and semiconductor memories (e.g., mask ROMs, PROMs (programmable ROMs), EPROMs (erasable PROMs), flash ROMs, and RAMs (random access memories)). Additionally, the program can also be provided to the computer through various types of transitory computer-readable media.

[0208] The effects of the machining simulation device and the machining simulation method of the above-described embodiments are that the transfer function of the machine tool can be obtained without the need for data collection during the trial operation of the machine tool and expertise for calculating the transfer characteristics.

[0209] The above has described the present disclosure, but the present disclosure is not limited to the above-described respective embodiments and modified examples. These embodiments and modified examples can be subjected to various additions, substitutions, changes, partial deletions, etc. within the scope not departing from the gist of the present disclosure or within the scope not departing from the gist of the present disclosure derived from the content described in the claimed scope of patent protection and its equivalents.

[0210] In addition, these embodiments and modified examples can also be implemented in combination. For example, in the above-described embodiments, the order of each action and the order of each process are shown as an example and are not limited thereto.

[0211] Regarding the above-described embodiments, the following remarks are further disclosed.

[0212] (Supplementary Note 1)

[0213] A machining simulation device 200, comprising:

[0214] A transfer characteristic generation unit 210 that generates the transfer characteristics of a machine tool;

[0215] A simulation execution unit 220 that uses the transfer characteristics to simulate the behavior of the machine tool,

[0216] The transfer characteristic generation unit includes:

[0217] A control information acquisition unit 211 that acquires control information including the motor information of the machine tool and the control parameters of the motor control system of the machine tool from a storage unit;

[0218] A motor characteristic calculation unit 212 that calculates motor characteristics based on the motor information;

[0219] A control characteristic calculation unit 213 that calculates the control characteristics of the motor control system based on the control parameters;

[0220] A transfer characteristic calculation unit 214 that calculates the transfer characteristics satisfying a predetermined requirement based on the motor characteristics and the control characteristics,

[0221] The predetermined requirement includes at least one of the response frequency of position control, the response frequency of speed control, the natural vibration frequency of the machine tool, and the resonance frequency between the driving part and the driven part in the machine tool.

[0222] (Supplementary Note 2)

[0223] The machining simulation device according to Supplementary Note 1, wherein,

[0224] The motor information includes at least one of the motor inertia, the inertia ratio, and the spring constant of the motor,

[0225] The control parameters include at least one of the position control proportional gain, the speed loop gain, the speed control integral gain, and the speed control proportional gain.

[0226] (Supplementary Note 3)

[0227] The machining simulation device according to Supplementary Note 2, wherein,

[0228] The motor characteristic calculation unit 212 calculates the motor characteristics using a rigid body system model including the motor inertia and the inertia ratio, or a two-inertia system model including the motor inertia, the inertia ratio, and the spring constant.

[0229] (Supplementary Note 4)

[0230] The machining simulation device according to Note 2, wherein,

[0231] The control characteristic calculation unit 213 calculates the control characteristics using the position control proportional gain.

[0232] (Note 5)

[0233] The machining simulation device according to Note 2, wherein,

[0234] The control characteristic calculation unit 213 calculates the control characteristics using the speed loop gain, or the speed loop gain, the speed control integral gain, and the speed control proportional gain.

[0235] (Note 6)

[0236] The machining simulation device according to Note 1, wherein,

[0237] The motor characteristics include at least one of motor inertia, inertia ratio, and spring constant,

[0238] The control characteristics include at least one of position control proportional gain, speed loop gain, speed control integral gain, and speed control proportional gain,

[0239] The transfer characteristic calculation unit 214 changes at least one of the motor inertia, the inertia ratio, the spring constant, the position control proportional gain, the speed loop gain, the speed control integral gain, and the speed control proportional gain so that the transfer characteristics satisfy the predetermined requirements.

[0240] (Note 7)

[0241] The machining simulation device according to Note 1, wherein,

[0242] The transfer characteristic calculation unit 214 adds load inertia to the motor inertia, or combines the motor inertia and the load inertia through a spring element so that the transfer characteristics satisfy the predetermined requirements.

[0243] (Note 8)

[0244] A machining simulation method, wherein,

[0245] The following processes are performed by a computer:

[0246] A process of calculating motor characteristics based on motor information of a machine tool;

[0247] A process of calculating control characteristics of the motor control system of the machine tool based on control parameters of the motor control system of the machine tool;

[0248] A process of calculating a transfer characteristic that meets a predetermined requirement based on the motor characteristics and the control characteristics;

[0249] A process of simulating the behavior of the machine tool using the transfer characteristic,

[0250] The predetermined requirement includes at least one of a response frequency of position control, a response frequency of speed control, a natural vibration frequency of the machine tool, and a resonance frequency between a driving part and a driven part in the machine tool.

[0251] Explanation of reference numerals

[0252] 10 Machining simulation system,

[0253] 100 Control device of the machine tool,

[0254] 101 Storage unit,

[0255] 200 Machining simulation device,

[0256] 210 Transfer characteristic generation unit,

[0257] 211 Control information acquisition unit,

[0258] 212 Motor characteristic calculation unit,

[0259] 213 Control characteristic calculation unit,

[0260] 214 Transfer characteristic calculation unit,

[0261] 220 Simulation execution unit.

Claims

1. A machining simulation device, characterized in that, it comprises: a transfer characteristic generation unit that generates a transfer function representing the transfer characteristics of a machine tool; and a simulation execution unit that uses the transfer function to simulate the behavior of the machine tool, the transfer characteristic generation unit includes: a control information acquisition unit that acquires control information including the motor information of the machine tool and the control parameters of the motor control system of the machine tool from a storage unit; a motor characteristic calculation unit that calculates motor characteristics based on the motor information; a control characteristic calculation unit that calculates the control characteristics of the motor control system based on the control parameters; and a transfer characteristic calculation unit that calculates the transfer function satisfying a predetermined requirement based on at least one of the motor characteristics and the control characteristics, the transfer function calculated by the transfer characteristic calculation unit includes at least one of the motor characteristics and the control characteristics, the predetermined requirement includes at least one of the response frequency of position control, the response frequency of speed control, the natural vibration frequency of the machine tool, and the resonance frequency between the driving part and the driven part in the machine tool, and is provided by the user.

2. The machining simulation device according to claim 1, characterized in that, the motor information includes at least one of the motor inertia, the inertia ratio, and the spring constant of the motor, the control parameters include at least one of the position control proportional gain, the speed loop gain, the speed control integral gain, and the speed control proportional gain.

3. The machining simulation device according to claim 2, characterized in that, the motor characteristic calculation unit calculates the motor characteristics using a rigid body system model including the motor inertia and the inertia ratio, or a double inertia system model including the motor inertia, the inertia ratio, and the spring constant.

4. The machining simulation device according to claim 2, characterized in that, the control characteristic calculation unit calculates the control characteristics using the position control proportional gain.

5. The machining simulation device according to claim 2, characterized in that, the control characteristic calculation unit calculates the control characteristics using the speed loop gain, or the speed loop gain, the speed control integral gain, and the speed control proportional gain.

6. The machining simulation device according to claim 1, characterized in that, the motor characteristics include at least one of the motor inertia, the inertia ratio, and the spring constant, the control characteristics include at least one of the position control proportional gain, the speed loop gain, the speed control integral gain, and the speed control proportional gain, the transfer characteristic calculation unit changes at least one of the motor inertia, the inertia ratio, the spring constant, the position control proportional gain, the speed loop gain, the speed control integral gain, and the speed control proportional gain so that the transfer function satisfies the predetermined requirement.

7. The machining simulation device according to claim 1, characterized in that, The transfer characteristic calculation unit adds the motor inertia to the load inertia or combines the motor inertia and the load inertia using a spring element so that the transfer function satisfies the predetermined requirements.

8. A machining simulation method, characterized in that the following processes are performed by a computer: a process of calculating motor characteristics based on motor information of a machine tool; a process of calculating control characteristics of the motor control system based on control parameters of the motor control system of the machine tool; a process of calculating a transfer function representing transfer characteristics of the machine tool that satisfies predetermined requirements based on at least one of the motor characteristics and the control characteristics; and a process of simulating the behavior of the machine tool using the transfer function, the transfer function includes at least one of the motor characteristics and the control characteristics, the predetermined requirements include at least one of a response frequency of position control, a response frequency of speed control, a natural vibration frequency of the machine tool, and a resonance frequency between a driving part and a driven part in the machine tool, and are provided by a user.

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