Industrial machinery change estimation device

Abstract

The present invention makes it possible to estimate cutting forces and cutting tool wear in a cutting tool.　Provided is an estimation device comprising: an NC program interpretation unit that interprets an NC program; a command generation unit that interpolates command points from the NC program and generates a command value; a feedback control unit that causes the driving of an electric motor that drives a feed shaft and a main shaft to track the command value; a machine configuration information unit storing characteristic values indicating characteristics of at least one from among a work material, a cutting tool, and the electric motor; a cutting force estimation unit that estimates a cutting force in the cutting tool on the basis of a torque command and the characteristic values stored in the machine configuration information unit; a matching unit that matches time series data of the estimated cutting force with time series data of a measured cutting force; a parameter optimization unit that calculates, on the basis of a matching result, optimal parameters necessary for calculations in the estimation of the cutting force and an estimation of cutting tool wear; and a display control unit that displays the cutting force.

Description

[Technical Field]

[0001] The present invention relates to an estimation device for estimating changes in industrial machinery, and more particularly to an estimation device for estimating cutting force and wear of at least a cutting tool in industrial machinery. [Background technology]

[0002] To improve the quality of products manufactured by industrial machines that perform cutting processes, such as machine tools and cutting robots, it is important to select appropriate tools and cutting conditions. The materials and geometries of the cutting tool and workpiece affect various elements of the cutting phenomenon, such as cutting tool wear, chatter vibration during cutting, and chip evacuation characteristics of the removed metal. Apparatuses for estimating cutting forces or tool wear using simulations are described, for example, in Patent Documents 1 and 2.

[0003] Patent Document 1 describes a machine tool that can inspect the machining quality in real time during machining and can prevent the production of workpieces with poor machining quality. Specifically, Patent Document 1 describes that the machine tool includes a tool that comes into contact with a workpiece to machine the workpiece, a state quantity data acquisition unit that acquires state quantity data of the workpiece and the tool, a state quantity estimation data calculation unit that calculates state quantity estimation data such as the machining resistance (corresponding to cutting force) of the tool from a simulation model including an apparatus dynamic characteristic model that indicates the dynamic characteristics of the tool and a workpiece model that indicates the target shape of the workpiece, and a machining state calculation unit that calculates machining state data that indicates the machining state of the workpiece based on the state quantity data and the state quantity estimation data.

[0004] Patent Document 2 describes a machining control device that can reduce machining errors. Specifically, Patent Document 2 describes a machining control device that includes a rotational speed determination processing unit that, when the rotary tool vibrates due to intermittent cutting resistance (Fy) generated in the rotary tool during intermittent cutting, determines the rotational speed (S) of the rotary tool so as to reduce the amplitude of the rotary tool based on the vibration state of the rotary tool and the vibration phase (θ) of the rotary tool when the rotary tool is subjected to the cutting resistance (Fy), and a control unit that controls the rotational speed (S) of the rotary tool based on the determined rotational speed (S). Patent Document 2 also describes a cutting resistance calculation unit that calculates an estimated value of the cutting resistance, and a tool wear amount estimation unit that estimates the wear amount of the cutting portion of the rotary tool.

[0005] Patent Document 3 describes a method for predicting tool wear that can accurately predict the amount of tool wear before machining in a range from low-speed cutting to high-speed cutting. Specifically, Patent Document 3 describes that the amount of tool wear is predicted from a prediction formula that includes a term that indicates the effect of abrasive wear caused by hard inclusions in the workpiece material and a term that indicates the effect of thermal diffusion wear caused by hard inclusions in the workpiece material, and therefore it is possible to accurately predict the amount of tool wear that takes into account abrasive wear that occurs mainly in the low-speed or medium-speed cutting region and thermal diffusion wear that occurs mainly in the high-speed cutting region. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2020-110922 [Patent Document 2] Republished Patent No. WO2013 / 038532 [Patent Document 3] Japanese Patent Application Laid-Open No. 2008-221454 Summary of the Invention [Problem to be solved by the invention]

[0007] Cutting forces can now be predicted through simulation. Most theoretical research into cutting analysis attempts to demonstrate the validity of a model by first obtaining characteristic data through basic cutting tests limited to specific equipment and processing methods that are different from the actual manufacturing process, and then performing simulations based on this data. However, in manufacturing sites where early start-up of production is desired, there are many pieces of equipment and processing methods, and it is not realistic to conduct thorough basic testing for each piece of equipment and processing method. Considering that it is desirable to modify the basic cutting data based on data obtained during actual manufacturing, there is a need for an estimation device for estimating the cutting force of a cutting tool that modifies the basic cutting data using data obtained from actual processing in actual production, is compatible with various equipment or processing, and can complete estimated calculations within the actual processing time. [Means for solving the problem]

[0008] A representative aspect of the present disclosure is an estimation device that estimates a change in an industrial machine, an NC program interpretation unit that interprets an NC program that defines the positioning of the feed axis and the speed control of the spindle; a command generating unit that interpolates command points from the NC program interpreted by the NC program interpreting unit and generates a position command value or a speed command value; a feedback control unit that performs feedback control to make the drive of the electric motors that drive the feed axes and the spindle follow the position command value or the speed command value; a machine configuration information unit that stores characteristic values ​​indicating at least one characteristic of a workpiece, a cutting tool, and the electric motor; a cutting force estimation unit that estimates a cutting force of the cutting tool based on a torque command obtained by the feedback control unit as a result of feedback control and a characteristic value held by the machine configuration information unit; a matching unit that matches the time series data of the estimated cutting force output from the cutting force estimating unit with the time series data of the actually measured cutting force; a parameter optimization unit that calculates optimal parameters required for the cutting force estimation unit to calculate the cutting force estimation based on the matching result output from the matching unit; and a display control unit that displays the cutting force estimated by the cutting force estimation unit; The present invention provides an estimation device for estimating changes in industrial machinery, comprising: [Effects of the Invention]

[0009] According to each aspect of the present disclosure, it is possible to provide a cutting force estimation device for a cutting tool that can correct basic cutting data using data obtained from actual machining, can respond to each machining, and can complete estimated calculations within the actual machining time. This makes it possible to apply the device to predict changes in industrial machinery and preventive maintenance. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a block diagram illustrating a configuration of an estimation device that estimates a change in an industrial machine according to an embodiment of the present disclosure. [Figure 2] FIG. 1 is a diagram showing a two-inertia system model. [Figure 3] FIG. 10 is an explanatory diagram showing an example in which the F-number of a program is changed. [Figure 4] FIG. 10 is a characteristic diagram showing two sets of time series data of actually measured cutting forces. [Figure 5] 10 is an explanatory diagram showing the estimated wear amount and the transition of the wear amount with respect to the actual cutting force. FIG. [Figure 6] 10A and 10B are diagrams showing an XYZ trajectory created by simulation and an XYZ trajectory created by an actual device. [Figure 7] FIG. 10 is a diagram showing an example of a display screen of a display unit that displays a possibility of a malfunction. [Figure 8] FIG. 10 is a diagram showing an example of matching of cutting feed intervals between simulation data (upper row) and actual machine measurement data (lower row) for each tool use interval. [Figure 9] FIG. 10 is a diagram showing an example of simulation results and actual measurement data when cutting coefficient parameters are identified through optimization. [Figure 10] FIG. 3 is a diagram illustrating an example of a display screen of a display unit. [Figure 11] FIG. 10 is a diagram illustrating an example of a speed profile generated by a command generating unit. [Figure 12] FIG. 3 is a diagram illustrating an example of a display screen of a display unit. [Figure 13] 10 is a flowchart illustrating an operation of an estimation calculation unit. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings.

[0012] FIG. 1 is a block diagram showing the configuration of an estimation device that estimates a change in an industrial machine according to an embodiment of the present disclosure. The estimation device 10 includes an estimation calculation unit 100, a storage unit 200, and a display unit 300. The estimation calculation unit 100 serves as a simulation device and includes an NC program interpretation unit 101, a command generation unit 102, a feedback control unit 103, a machine model 104, a machine configuration information unit 105, a cutting force estimation unit 106, a wear estimation unit 107, a coincidence calculation unit 108, a judgment unit 109, a production line estimation unit 110, a matching unit 111, and a parameter optimization unit 112. The friction estimation unit 107, the coincidence calculation unit 108, the judgment unit 109, and the production line estimation unit 110 are provided as needed. One or more of the friction estimation unit 107, the coincidence calculation unit 108, the judgment unit 109, and the production line estimation unit 110 may be provided. The display unit 300 includes a display control unit 301 . The industrial machines whose changes are estimated by the estimation device 10 are, for example, machine tools and cutting robots. Each component of the estimation device 10 will be described below. First, the configuration of the estimation calculation unit 100 will be described.

[0013] (NC program interpretation part 101) The NC program interpretation unit 101 determines the travel distance, travel path, and command speed based on input information such as an NC (Numerical Control) program (which becomes the machining program), CNC (Computerized Numerical Control) parameters, macro variables, workpiece origin offset, and tool offset value, which are output from the storage unit 200. The NC program interpretation unit 101 interprets the NC program that defines the positioning of the feed axis and the operation of spindle speed control, breaks down the NC program into each code and value, and determines the travel distance, travel path, and command speed. The NC program interpretation unit 101 performs, for example, the following interpretations (A), (B), (C), and (D). (A) Codes M03, M04, and M05 are used to convert the spindle to clockwise rotation, counterclockwise rotation, or stop rotation. (B) Using G00, G01, G02, and G03, the main axis is moved to the specified coordinates at rapid feed, the main axis is moved to the specified coordinates at cutting feed, and the case is divided into clockwise circular interpolation and counterclockwise circular interpolation, and converted into the path and movement distance of each servo axis. (C) For canned cycles and tool change operations, convert them into equivalent G code and M code. (D) Add the tool offset value to the travel distance.

[0014] (Command generation unit 102) The command generation unit 102 generates interpolation data by interpolating points on the movement path at an interpolation period based on the movement distance, movement path such as a straight line or a circular arc, and command speed obtained by the NC program interpretation unit 101, generates an acceleration / deceleration profile based on the interpolation data, and further distributes the data to each control axis, thereby giving a position command value or a speed command value for each control period to the servo motor that serves as the feed axis motor and the spindle motor that serves as the spindle motor. The command generating unit 102 performs the following operations (E), (F), (G), (H), and (I). (E) Calculate the distance traveled. (F) Create a velocity and position profile at the tool tip that satisfies the travel distance, command velocity, and acceleration / deceleration parameters set by the machine. (G) The profile is discretized for each control cycle. (H) The discretized profile is distributed to commands for each axis. (I) Filtering is performed on the distributed command values ​​for each axis.

[0015] (Feedback control unit 103) The feedback control unit 103 performs feedback control to make the driving of the electric motors that drive the feed axis and the spindle follow the position command value or the speed command value generated by the command generating unit 102. The configuration of the feedback control unit is the same as that of the feedback control unit of the actual industrial machine, and since the configuration of the feedback control unit of the actual machine is already known, detailed description will be omitted. For example, as the feedback control unit 103, a subtractor that calculates the difference between a position command value and a position detection value that has been fed back, and a control unit that is connected to the subtractor and performs speed feedback and current feedback, as described in Japanese Patent Application Laid-Open No. 2019-128830, can be used. In this embodiment, it is sufficient to feedback at least one of the speed detection value, the position detection value, and the current detection value. The feedback control unit 103 outputs a torque command, which is generated in the feedback control unit 103 and serves as servo data, to the cutting force estimation unit 106 .

[0016] (Machine Model 104) The machine model 104 is created using, for example, a two-inertia system. Such a machine model is described, for example, in "Research on Low-Frequency Vibration Suppression Control Using a Two-Inertia System Model for the Feed Axis of an NC Machine Tool," Journal of the Japan Society for Precision Engineering, Vol. 82, No. 8, pp. 745-750, 2016, and JP 2019-009858 A. FIG. 2 is a diagram showing a two-inertia system model. The machine model 104 shown in FIG. 2 is a machine model of a feed axis. As shown in FIG. 2, the two-inertia system model is a model in which a servo motor 1041, which serves as an electric motor, and a machine 1042 are connected by a spring 1043A and a damper 1043B, which correspond to a ball screw.

[0017] The mass of the servo motor 1041 and the mass of the machine 1042 are expressed as Jm , J L , the spring constant of the spring 1043A is K, the damper constant of the damper 1043B is C, the drive torque (torque command) of the servo motor 1041 is u, the combined force of the spring 1043A and the damper 1043B is T, and the motor speed is V. m , the machine speed is V L Then, V m ,V L The equation of motion and the resultant force T of the spring 1043A and the damper 1043B are expressed as in Equation 1 (Equation 1 below).

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[0018] The spindle is a motor shaft for rotating tools. It is the same as the feed axis in that it drives the motor and controls the machine end, but unlike the feed axis, it transmits rotational motion directly at the machine end rather than translational motion. Therefore, in the mechanical model of the spindle, the spindle does not have a conversion mechanism using a ball screw.

[0019] (Machine configuration information section 105) The machine configuration information unit 105 acquires and stores characteristic values ​​indicating at least one characteristic of the workpiece (workpiece), cutting tool, and electric motor from the storage unit 200. The characteristic values ​​include values ​​calculated using mathematical expressions, an estimated cutting force estimated by the cutting force estimation unit 106, and an estimated wear amount estimated by the wear estimation unit 107. The characteristic values ​​include, for example, cutting distance, cutting coefficient, estimated cutting force, estimated wear amount, temperature of the cutting tool, servo data such as torque command, digitized shape and contact length of the workpiece, and the like. The machine configuration information unit 105 also stores time series data of the estimated cutting force and time series data of the estimated wear amount.

[0020] The mechanical configuration information unit 105 may calculate and update the characteristic values ​​possessed by the mechanical configuration information unit 105 by using at least one set of time series data of the actual cutting force acquired from the memory unit 200 or time series data of the estimated cutting force estimated by the cutting force estimation unit 106. For example, the machine configuration information unit 105 calculates a cutting coefficient from time-series data of the actually measured cutting force and updates the cutting coefficient. The machine configuration information unit 105 may also calculate a cutting coefficient from time-series data of the stored estimated cutting force and update the cutting coefficient.

[0021] In addition, the machine configuration information unit 105 may edit the NC program to satisfy the target cycle time by using at least one set of time series data of the actual cutting force obtained from the memory unit 200 or time series data of the estimated cutting force estimated by the cutting force estimation unit 106. If you have time series data on cutting force, you can determine the cycle time of the target time series data. In the case of actually measured cutting force, the cycle time for the NC program that operates the industrial machine is known, and in the case of estimated cutting force, the cycle time for the simulation program executed on the estimation calculation unit 100 is known. Changing any part of the NC program that operates an industrial machine (for example, changing the F value or tool path) will change the cycle time. Conversely, to match the target cycle time, the G code of some NC programs is changed by changing the F value or tool path, etc. Fig. 3 is an explanatory diagram showing an example in which the F-value of a program has been changed. In Fig. 3, the F-value in the NC program before editing is shown as F800, but in the NC program after editing, the F-value is shown as F1000.

[0022] The machine configuration information unit 105 calculates a characteristic value representing the change over time of the cutting tool by using at least two sets of time series data of the actual cutting force obtained from the memory unit 200 or time series data of the estimated cutting force estimated by the cutting force estimation unit 106. Figure 4 is a characteristic diagram showing two sets of time-series data of measured cutting force. In Figure 4, the maximum torque value indicating the cutting force at the 3000th cut is greater than the maximum torque value indicating the cutting force at the first cut. Figure 4 shows that the maximum torque value indicating the cutting force increases with age, indicating deterioration over time, and indicates the state of deterioration of the cutting tool over time.

[0023] The machine configuration information unit 105 can assign a label to each characteristic value. For example, the machine configuration information unit 105 labels the estimated cutting force acquired from the cutting force estimation unit 106 as normal or abnormal according to a certain threshold. For example, the estimated cutting force is labeled as abnormal when the torque reaches 100%. The machine configuration information unit 105 labels the estimated wear amount acquired from the wear estimation unit 107 as normal or abnormal according to a certain threshold. For example, the wear amount is labeled as abnormal when the distance and number of times reach the tool life setting value, the torque reaches 100%, the wear amount reaches a threshold VB, or when a tool is determined to be broken.

[0024] Furthermore, the machine configuration information unit 105 assigns labels (normal, abnormal) to multiple abnormal factors (for example, input / output characteristics or vibration of the motor, estimated cutting force or estimated wear amount of the cutting tool) for the time-dependent states of the electric motor, cutting tool, ball screw, etc. Then, the machine configuration information unit 105 calculates how accurate the label is based on the cutting force at that time, etc., and sets the probability as the confidence level. The machine configuration information unit 105 can also assign labels and certainty factors to the electric motor, cutting tool, and ball screw themselves. The machine configuration information unit 105 calculates the labels and certainty factors for the electric motor, cutting tool, and ball screw themselves from a combination of the certainty factors of each abnormality. If there is even one abnormal label, the electric motor or tool is also considered to be abnormal. The certainty factor for the electric motor or tool is determined to be the probability of the highest certainty factor of the abnormality factor.

[0025] The machine configuration information unit 105 can identify the cause of an abnormality by assigning at least one label to a combination of characteristic values. As described above, the machine configuration information unit 105 labels multiple characteristic values ​​as normal or abnormal according to their respective thresholds. It then labels combinations of characteristic values ​​as normal or abnormal. Each of the multiple characteristic values ​​has an abnormality cause label (normal, abnormal), and the combination can have an overall label (normal, abnormal), making it possible to identify the cause of an abnormality. For example, the machine configuration information unit 105 assigns a normal label to a cutting tool if both the estimated cutting force and the estimated wear amount are normal overall, and an abnormal label to a cutting tool if either or both of the estimated cutting force and the estimated wear amount are abnormal. In this way, if the overall label is abnormal, it can be determined whether the cause of the abnormality is either or both of the estimated cutting force and the estimated wear amount.

[0026] (Cutting force estimation unit 106) The cutting force estimation unit 106 estimates the cutting force of the cutting tool based on the torque command output from the feedback control unit 103 and the characteristic values ​​stored in the machine configuration information unit 105. Here, the characteristic values ​​stored in the machine configuration information unit 105 are the quantified shape or contact length of the workpiece. Cutting force is the resistance of the material to the penetration of the cutting tool, and refers to the force required to continue cutting. Torque [Nm] is calculated by multiplying the cutting force by the radius [m], so cutting force can be used to mean almost the same thing as torque.

[0027] The estimated cutting force can be calculated using the instantaneous cutting force model described below. The cutting edge of the cutting tool is cut into minute pieces in the vertical direction. The vertical size of the micro-blade is defined as dz. Here, the cutting forces acting on the micro-blade when the cutting tool cuts the workpiece are defined as dFt for the force tangential to the tool, dFr for the radial force, and dFa for the axial force. Also, let h be the length (called the cutting thickness) that the micro-blade cuts off the workpiece in one rotation. The cutting thickness h depends on the position z of the micro-blade and the rotation angle θ. At this time, the instantaneous cutting model assumes that the relationship in Equation 2 (below Equation 2) holds. Here, the cutting coefficients Kte, Ktc, Kre, Krc, Kae, and Kac are coefficients determined by the physical relationship between the tool and workpiece. In particular, the cutting coefficients Ktc, Krc, and Kac are coefficients equivalent to the specific cutting resistance.

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[0028] If the shape of the workpiece is known in advance, the cutting force can be calculated by numerically representing the shape of the workpiece in some form on a computer and simulating the cutting process at discrete times. For example, a method called Z-Map considers a grid space divided in the X and Y directions, and numerically represents the workpiece shape by recording the height of the workpiece in each cell. The cutting tool is represented by a small plate separated in the height direction. The positions of the cutting tool and workpiece are updated every small amount of time, the height of the workpiece cell where the tool comes into contact is reduced, and a cutting force is generated according to the thickness of the cut that occurs in that area, performing a simulation.

[0029] If the shape of the workpiece is not known in advance, Z-Map simulation cannot be used. However, by using torque data measured during machining, it is possible to see at what position the tool is generating torque. In other words, by using the measurement data, it is possible to estimate the position of the workpiece. Furthermore, it is also possible to estimate the specific cutting resistance of the workpiece.

[0030] Here, we will explain a method for performing cutting simulation (simulation using contact length) when the specific cutting resistance is known and the workpiece shape is unknown. Since torque can be considered as the tangential force multiplied by the tool radius, the cutting torque dT applied to the microplate of the cutting tool is given by the following equation (Equation 3 below).

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[0031] In a simulation using contact length Cz, the average chip thickness h' is calculated from the machining conditions of feed rate and rotation speed. If the specific cutting resistance is known, the cutting torque can be simulated by calculating contact length Cz at each position. In reality, if measurement data is available, the contact length at each position (basic cutting data) can be calculated using Equation 5. The same applies to cutting forces in directions other than the tangential direction.

[0032] (Estimation of chatter vibration) The cutting force estimation unit 106 estimates chatter vibrations occurring in the spindle of the cutting tool, the workpiece, or both, based on the torque command output from the feedback control unit 103.

[0033] Chatter vibrations can be broadly divided into two types: forced chatter vibrations and self-excited chatter vibrations. Forced chatter vibration occurs when some external, forced vibration cause is amplified by the vibration characteristics of the machine. Vibration sources include the periodic cutting force of a milling cutter, cutting force fluctuations caused by the periodicity of chip generation when cutting hardened steel, or misalignment of a rotating shaft. Self-excited chatter vibration is an unstable phenomenon that amplifies vibration in the cutting process through a feedback loop.

[0034] Forced chatter vibration can be considered a problem of deterioration of the machining equipment itself, so from the perspective of preventive maintenance, priority is given to eliminating forced chatter vibration. From a practical standpoint of preventive maintenance, it is better to model from actual measurement data that "there are resonant elements in the mechanical elements of the positioning system and spindle rotation system, and the amplification of the dynamic cutting force occurs only when a dynamic cutting force of a specific frequency component is applied," and then reverse-calculate the parameters of the resonant elements using modal analysis.

[0035] Considering the r-th order modal transfer function Gr(s) shown in Equation 6 (Equation 6 below), it can be expressed by equivalent stiffness Kr, equivalent damping ratio ζr, and equivalent resonance angular frequency ωr.

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[0036] The cutting force estimation unit 106 obtains the cutting force amplification factor by calculating the ratio of the spindle torque measurement value during cutting at a certain point in time to the spindle torque measurement value during cutting at another point in time. By plotting these amplification factors at different spindle rotation speeds, the frequency transfer function during cutting can be obtained. Although the frequency step size depends on the operating conditions or NC program, the frequency transfer function can be obtained by narrowing it down to the main frequency range. By observing the fluctuations in this frequency transfer function, it is possible to comprehensively grasp the cutting force amplification for various spindle rotation speeds. If the frequency transfer function increases only at a specific spindle rotation speed, a physical model expressing forced chatter vibration can be obtained by expressing it as the resonance mode shown above.

[0037] (Wear estimation unit 107) The wear estimation unit 107 estimates the wear of the cutting tool based on the fluctuation of the characteristic values ​​held by the machine configuration information unit 105 . The wear of cutting tools is caused by the wear of the cutting edge, which is caused by friction with the workpiece and chips. The wear of a cutting tool can be divided into wear on the rake face and wear on the flank face, but unless the cutting speed is high, wear on the flank face is dominant. The wear rate of flank wear, dW / dL, can be calculated using the following equation (7): where W is the wear amount of flank wear, L is the cutting distance, K is a coefficient determined by the shape of the agglomerated particles, H is the hardness of the cutting tool side, and σ t is the normal stress on the wear surface.

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[0038] On the other hand, when the cutting speed is high, rake face wear becomes dominant, and the wear rate of rake face wear, dW / dL, can be calculated using the following equation (Equation 9): where W is the amount of flank wear, L is the cutting distance, C and λ are characteristic constants determined by the combination of the cutting tool and the workpiece material, and T is the temperature of the cutting tool.

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[0039] The wear estimation unit 107 cumulatively calculates the amount of wear of the cutting tool when the NC program is repeatedly executed, and estimates the resulting fluctuation in cutting force. An example of a document describing the change in cutting force when flank wear occurs is "Flank Wear of Cutting Tools and Changes in Cutting Force" by Okushima Hiroji and Hitomi Katsuto, Precision Machinery, Vol. 29, No. 4 (1963). This document describes that the cutting force when there is flank wear width is expressed by the following mathematical formula 11.

[0040] The above document states that the main component of cutting force F h , back force F v The initial main force and thrust force are F h0 , F v0 When the wear width is l and the growth functions related to the wear width l are f(l) and g(l), respectively, this is expressed by Equation 11 (hereinafter Equation 11).

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[0041] The wear estimation unit 107 estimates the limit wear amount of the cutting tool and the time when the limit wear amount will be reached. Limit wear amount W lim is the limit cutting distance L lim By setting the above, calculation can be performed using Equation 7 or Equation 9. Limit cutting distance L min is not the set lifespan but the maximum usable cutting distance, and will change depending on the required machining accuracy, so enter an appropriate value. The time when the limit wear amount is reached is the limit cutting distance L lim The time it takes for the limit cutting distance L lim The period until lim is the cycle time t required for one NC program execution. ctIf the cutting distance L1 per cycle time is known, it can be estimated using the following formula 13 (the following formula 13).

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[0042] (Concordance calculation unit 108) The coincidence calculation unit 108 calculates the coincidence between the time series data of the estimated cutting force output as a result from the cutting force estimation unit and the time series data of the actually measured cutting force. The degree of agreement between the time series data of the estimated cutting force and the time series data of the actually measured cutting force is calculated as two types of agreement: the degree of agreement for the XYZ trajectory and the cycle time. Figure 6 shows the XYZ trajectory created by simulation and the XYZ trajectory created by the actual device. When the similarity of the images was checked, the match rate was 99.98%. When the time-dependent change in displacement of each axis (time series data) created by the simulation was compared with the time-dependent change in displacement of each axis (time series data) during actual machining using the NC program on the actual machine, the agreement between the cycle time of the simulation and the cycle time of the actual machining using the NC program on the actual machine was 99.7%.

[0043] (Judgment unit 109) The determination unit 109 determines whether or not the cutting force and wear amount estimated by the cutting force estimation unit 106 and the wear estimation unit 107 deviate from the normal range. The criteria for determining whether or not they are within the normal range are set arbitrarily, taking into account the limit torque value and limit wear amount.

[0044] (Production line estimation unit 110) The production line estimation unit 110 estimates the operation and aging of a production line by combining estimation devices for multiple industrial machines. The production line is set up with four industrial machines, two of which are machine tools A1 and A2, and the other two are cutting robots B1 and B2. The machine tool A1 is equipped with an estimation device 10 including the production line estimation unit 110 shown in FIG. 1. The machine tool A2 and the cutting robots B1 and B2 are equipped with estimation devices 10 excluding the production line estimation unit 110. The production line estimation unit 110 is connected to the estimation devices 10 of the machine tool A2 and the cutting robots B1 and B2 via a network such as a LAN. The production line estimation unit 110 receives, for example, cutting force F1 estimated by wear estimation unit 107 of estimation device 10 of machine tool A1. Furthermore, the production line estimation unit 110 receives, for example, cutting forces F2, F3, and F4 estimated by wear estimation unit 107 of estimation device 10 from machine tool A2 and cutting robots B1 and B2, respectively. From the time-series data of cutting forces F1, F2, F3, and F4, the production line estimation unit 110 detects that cutting robots B1 and B2 are operating normally and are unlikely to malfunction, but that machine tools A1 and A2 are likely to malfunction within one week. Furthermore, the production line estimation unit 110 detects that the entire production line, including both or either machine tool A1 and machine tool A2, is likely to malfunction within one week. FIG. 7 is a diagram showing an example of a display screen of the display unit 300 that displays the possibility of a malfunction.

[0045] (Matching section 111) (Time series data matching method between actual measurement control data and simulated control data) When comparing the behavior of the actual machine with the behavior in the simulation, it is necessary to match the actual machine measurement data and the simulation data as time-series signals. Furthermore, it is also necessary to match the actual machine measurement data and simulation data with the NC program. The simulation data and actual machine measurement data are output from the storage unit 200 or the machine configuration information unit 105, and the matched simulation data and actual machine measurement data are output to the parameter optimization unit 112. Here, the following rules are established for the simulation data and the actual machine measurement data, and the NC program, simulation data, and actual machine measurement data are associated in a two-stage procedure: the tool use section and the cutting feed section. (1) Divide the time series data into sections where each tool is used, with tool changes as the dividing point. (2) Correspondence between sections where each tool is used is made. (3) Extract the section where a signal indicating that each tool is in cutting feed mode is on while each tool is being used. (4) Correspondence between sections of the cutting feed signal. FIG. 8 is a diagram showing an example of matching of the cutting feed interval between the simulation data (upper row) and the actual machine measurement data (lower row) for each tool use interval. The hatched areas with the same pattern are corresponding sections, and in all cases, the cutting feed sections correspond to each other.

[0046] (Parameter optimization unit 112) To perform the simulations described above, the parameters for running the simulation must match the actual cutting force. The parameter optimization unit 112 identifies in advance, for example, the parameters of the cutting coefficient, which is a parameter of the cutting force. The identification of the parameters of the cutting coefficients is performed on the assumption that the contact length is known at some positions. For example, in the case of drilling, the contact length is considered to coincide with the height of the cutting edge at a position where the cutting is in a steady state response. Therefore, such a position can be extracted and the cutting coefficients Kte and Ktc (which serve as basic cutting data) can be found based on the magnitude of the torque at that position (torque command output from the feedback control unit 103). FIG. 9 is a diagram showing an example of simulation results and actual measurement data when cutting coefficient parameters are identified through optimization.

[0047] The steady-state response points can be extracted by manually specifying them by the simulator user, or by finding points where the response is stable based on rules.The specific cutting resistance in directions other than the tangential direction can be calculated using oblique cutting theory. The parameters of the cutting coefficients are calculated by comparing the identified points matched by the matching unit using the characteristic values ​​and actual cutting forces stored in the machine configuration information unit 105. The parameters can be optimized by adjusting them for each machine tool and each machining operation. The parameter optimization unit 112 stores in the storage unit 200 the optimized parameters calculated based on the matched simulation data and actual device measurement data output from the matching unit 111 .

[0048] The estimation calculation unit 100 has been described above. Next, the storage unit 200 and the display unit 300 including the display control unit 301 will be described.

[0049] (Storage unit 200) The memory unit 200 stores data necessary for the simulation in the estimation calculation unit 100. For example, machine data, an NC (Numerical Control) program (which serves as a machining program), a CNC (Computerized Numerical Control) parameter, macro variables, a workpiece origin offset, a tool offset value, etc. are input and stored in the memory unit 200. In addition, for example, servo data such as cutting distance, cutting coefficient, estimated cutting force, estimated wear amount, cutting tool temperature, torque command, etc., digitized shape and contact length of the workpiece (workpiece), tool information, and actual measurement time series data are input and stored in the memory unit 200. The actual measurement time series data is, for example, time series data of actual measurement cutting force.

[0050] (Display unit 300, display control unit 301) The display unit 300 includes a display control unit 301, which displays at least one of the cutting force and the wear amount estimated by the cutting force estimation unit 106 and the wear estimation unit 107 on the display screen of the display unit 300. The display control unit 301 can display at least one of the current cutting force and the wear amount, and / or time series data of the cutting force and time series data of the wear amount.

[0051] The display control unit 301 can display at least one label provided by the machine configuration information unit 105 in combination with a confidence level. For example, the display control unit 301 displays labels of normality and abnormality and the confidence level for the electric motor and ball screw. Fig. 10 is a diagram showing an example of the display screen of the display unit 300. In Fig. 10, the gain characteristics of the electric motor are labeled as normal with a confidence level of 10%, the friction force characteristics of the electric motor are labeled as normal with a confidence level of 5%, and the vibration element characteristics of the electric motor are labeled as abnormal with a confidence level of 80%. Also in Fig. 10, the dead band of the input / output of the ball screw are labeled as normal with a confidence level of 5%, and the phase delay of the input / output of the ball screw are labeled as normal with a confidence level of 20%.

[0052] The display control unit 301 displays the limit wear amount of the cutting tool and the time when the limit wear amount will be reached, which are calculated by the wear estimation unit 107. The limit wear amount of the cutting tool and the time when the limit wear amount will be reached may be displayed numerically, or may be displayed as a graph as shown in FIG.

[0053] The display control unit 301 may display the chatter vibration results calculated by the cutting force estimating unit 106.

[0054] The display control unit 301 may display the cycle time of the NC program estimated based on the number of calculations required for the interpolation calculation of the command generating unit 102 NC program. The interpolation calculation performed by the command generating unit 102 can be considered as being divided into calculations for acceleration / deceleration and constant speed portions. During acceleration / deceleration, the calculation circuit operates for the time constant. Here, this refers to the time during the acceleration or deceleration section. At a constant speed, the circuit operates for the time at the specified feed rate, excluding the "acceleration / deceleration movement." For example, the speed profile shown in Figure 11 will be generated for the G-code indicated by "G01 X100. F1000." When a speed profile like this is created for each line of an NC program, the sum of the required times for all lines is the cycle time. This process of decoding each G-code into a speed profile is called command generation.

[0055] If the estimated cutting force estimated by the cutting force estimation unit 106 or the amount of wear estimated by the wear estimation unit 107 deviates from the normal range, the display control unit 301 displays an abnormality in the estimated value on the block diagram. Fig. 12 is a diagram showing an example of the display screen of the display unit 300. Fig. 12 shows that there is an abnormality in the characteristics of the vibration element of the electric motor.

[0056] The above describes the configuration of the estimation device 10. Next, the operation of the estimation calculation unit 100 of the estimation device 10 will be described using a flowchart. FIG. 13 is a flowchart showing the operation of the estimation calculation unit 100. In step S11, the NC program interpretation unit 101 interprets the NC program to determine the travel distance, travel path, and command speed. Then, the command generation unit 102 generates a position command value or a speed command value based on the travel distance, travel path (such as a straight line or a circular arc), and command speed.

[0057] In step S12, the feedback control unit 103 performs feedback control to make the drive of the electric motors that drive the feed axis and the main axis follow the position command value or speed command value generated by the command generation unit 102, and drives the servo motor 1041 that serves as the electric motor.

[0058] In step S13 , the cutting force estimation unit 106 estimates the cutting force of the cutting tool based on the torque command output from the feedback control unit 103 and the characteristic values ​​stored in the machine configuration information unit 105 .

[0059] In step S14, the wear estimation unit 107 estimates the wear of the cutting tool based on the fluctuation of the characteristic values ​​held by the machine configuration information unit 105.

[0060] In step S15, the display unit 300 includes a display control unit 301, which displays at least one of the cutting force and the amount of wear estimated by the cutting force estimation unit 106 and the wear estimation unit 107 on the display screen of the display unit 300.

[0061] In step S16, it is determined whether or not the NC program is to be executed continuously. If it is to be executed continuously, the process proceeds to step S11, and if it is not to be executed continuously, the process proceeds to step S17.

[0062] In step S17, the amount of wear of the cutting tool is cumulatively calculated, and the resulting fluctuation in cutting force is estimated. In FIG. 13, steps S13 and S14 are performed in parallel, but the process of step S13 may be performed before the process of step S14 or after the process of step S14.

[0063] As described above, the functional blocks included in the estimation device in this embodiment can be realized by hardware, software, or a combination of these. Here, being realized by software means being realized by a computer reading and executing a program.

[0064] In order to realize the functional blocks included in the estimation device in this embodiment by software or a combination thereof, specifically, each estimation device includes a calculation processing device such as a CPU (Central Processing Unit), an auxiliary storage device such as an HDD (Hard Disk Drive) that stores various control programs such as application software or an OS (Operating System), and a main storage device such as a RAM (Random Access Memory) that stores data temporarily required for the calculation processing device to execute the programs.

[0065] In the estimation device, the arithmetic processing unit reads application software or an OS from the auxiliary storage device, and while loading the read application software or OS into the main storage device, performs arithmetic processing based on the application software or OS. Furthermore, based on the results of this calculation, various hardware components of each device are controlled. This realizes the functional blocks of this embodiment.

[0066] Each component included in the estimation device can be realized by hardware including electronic circuits, etc. When the estimation device is configured by hardware, some or all of the functions of each component included in the estimation device can be configured 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).

[0067] The program can be stored and supplied to a computer using various types of non-transitory computer readable media. 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 disks), CD-ROMs (Read Only Memory), CD-Rs, CD-R / Ws, and semiconductor memories (e.g., mask ROMs, PROMs (Programmable ROMs), EPROMs (Erasable PROMs), flash ROMs, and RAMs (Random Access Memory)). The program may also be supplied to a computer by various types of transitory computer readable media.

[0068] 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 alone, and the present invention can be implemented in various modified forms within the scope that does not deviate from the gist of the present invention.

[0069] The estimation device according to the present disclosure can take various forms including the above-described embodiment, having the following configurations. (1) An estimation device (e.g., estimation device 10) that estimates a change in an industrial machine, an NC program interpretation unit (e.g., NC program interpretation unit 101) that interprets an NC program that defines the positioning of the feed axis and the speed control operation of the spindle; a command generating unit (for example, a command generating unit 102) that interpolates command points from the NC program interpreted by the NC program interpreting unit and generates a position command value or a speed command value; a feedback control unit (for example, a feedback control unit 103) that performs feedback control to make the drive of the electric motors that drive the feed axes and the spindle follow the position command value or the speed command value; a machine configuration information unit (e.g., machine configuration information unit 105) that stores characteristic values ​​indicating at least one characteristic of a workpiece, a cutting tool, and the electric motor; a cutting force estimation unit (e.g., cutting force estimation unit 106) that estimates a cutting force of the cutting tool based on a torque command obtained by the feedback control unit as a result of feedback control and a characteristic value held by the machine configuration information unit; a matching unit (for example, a matching unit 111) that matches the time series data of the estimated cutting force output from the cutting force estimation unit with the time series data of the actually measured cutting force; a parameter optimization unit (for example, a parameter optimization unit 112) that calculates optimal parameters required for the cutting force estimation unit to calculate the cutting force estimation based on the matching result output from the matching unit; An estimation device for estimating changes in industrial machinery, comprising: This estimation device can correct basic cutting data using data obtained as a result of feedback control, and estimate the cutting force and wear of the cutting tool, which can be applied to predicting changes in industrial machinery and preventive maintenance.

[0070] (2) a wear estimation unit (for example, a wear estimation unit 107) that estimates wear of the cutting tool based on a change in the characteristic value of the machine configuration information unit; Further comprising: the display control unit displays the amount of wear estimated by the wear estimation unit, the wear estimation unit cumulatively calculates the amount of wear of the cutting tool when the NC program is repeatedly executed, and estimates the resulting fluctuation in cutting force. The estimation device according to (1) above.

[0071] (3) The estimation device described in (1) above, further comprising a coincidence calculation unit (e.g., a coincidence calculation unit 108) that calculates the degree of coincidence between the time series data of the estimated cutting force output from the cutting force estimation unit and the time series data of the actually measured cutting force.

[0072] (4) An estimation device described in (1) or (2) above, comprising a judgment unit (e.g., judgment unit 109) that judges whether the cutting force and wear amount estimated by the cutting force estimation unit and the wear estimation unit deviate from the normal range.

[0073] (5) An estimation device according to any one of (1) to (4) above, wherein the mechanical configuration information unit calculates and updates characteristic values ​​held by the mechanical configuration information unit by using at least one set of time series data of the measured cutting force and time series data of the estimated cutting force output from the cutting force estimation unit.

[0074] (6) The estimation device according to any one of (1) to (4) above, wherein the machine configuration information unit calculates a characteristic value representing a change in the cutting tool held by the machine configuration information unit by using at least two sets of time series data of the actual cutting force or time series data of the estimated cutting force output from the cutting force estimation unit.

[0075] (7) An estimation device according to any one of (1) to (4) above, wherein the machine configuration information unit edits the NC program to satisfy the target cycle time by using at least one set of time series data of the actual cutting force or time series data of the estimated cutting force output from the cutting force estimation unit.

[0076] (8) The estimation device according to any one of (1) to (7) above, wherein the machine configuration information unit identifies an abnormality factor by assigning at least one label to a combination of characteristic values ​​of the machine configuration information unit.

[0077] (9) The estimation device according to any one of (1) to (8) above, wherein the display control unit displays at least one label provided by the machine configuration information unit in combination with a certainty factor.

[0078] (10) The estimation device according to any one of (1) to (9) above, wherein the wear estimation unit estimates a limit wear amount of the cutting tool and a time when the limit wear amount will be reached.

[0079] (11) The estimation device according to (10), wherein the display control unit displays the limit wear amount of the cutting tool calculated by the wear estimation unit and the time when the limit wear amount will be reached.

[0080] (12) The estimation device according to any one of (1) to (11) above, wherein the cutting force estimation unit estimates chatter vibrations occurring in a spindle of a cutting tool, a workpiece, or both, based on a torque command output from the feedback control unit.

[0081] (13) The estimation device according to (12) above, wherein the display control unit displays the chatter vibration result calculated by the cutting force estimation unit.

[0082] (14) The estimation device according to any one of (1) to (13), wherein the display control unit displays the cycle time of the NC program estimated based on the number of calculations required by the command generation unit for the interpolation calculation of the NC program.

[0083] (15) An estimation device according to any one of (1) to (14) above, wherein the display control unit displays an abnormality in the estimated value on a block diagram when the estimated cutting force estimated by the cutting force estimation unit or the amount of wear estimated by the wear estimation unit deviates from a normal range.

[0084] (16) The estimation device according to any one of (1) to (15) above, including a production line estimation unit (e.g., the production line estimation unit 110) that estimates the operation and aging of a production line by combining the estimation devices of a plurality of industrial machines. [Explanation of symbols]

[0085] 10 Estimation device 101 NC program interpretation unit 102 Command generation section 103 Feedback control section 104 Mechanical Model 105 Machine configuration information department 106 Cutting force estimation section 107 Wear estimation part 108 Matching degree calculation unit 109 Judgment section 110 Production Line Estimation Department 111 Matching Department 112 Parameter Optimization Unit 200 Storage section 300 Display 301 Display control unit

Claims

1. An estimation device for estimating a change in an industrial machine, an NC program interpretation unit that interprets an NC program that defines the positioning of the feed axis and the speed control of the spindle; a command generating unit that interpolates command points from the NC program interpreted by the NC program interpreting unit and generates a position command value or a speed command value; a feedback control unit that performs feedback control to make the drive of the electric motors that drive the feed axes and the spindle follow the position command value or the speed command value; a machine configuration information unit that stores characteristic values ​​indicating at least one characteristic of a workpiece, a cutting tool, and the electric motor; a cutting force estimation unit that estimates a cutting force of the cutting tool based on a torque command obtained by the feedback control unit as a result of feedback control and a characteristic value held by the machine configuration information unit; a matching unit that matches the time series data of the estimated cutting force output from the cutting force estimating unit with the time series data of the actually measured cutting force; a parameter optimization unit that calculates optimal parameters required for the cutting force estimation unit to calculate the cutting force estimation based on the matching result output from the matching unit; and a display control unit that displays the cutting force estimated by the cutting force estimation unit; An estimation device for estimating changes in industrial machinery, comprising:

2. a wear estimation unit that estimates wear of the cutting tool based on a variation in a characteristic value held by the machine configuration information unit; Further comprising: the display control unit displays the amount of wear estimated by the wear estimation unit, the wear estimation unit cumulatively calculates the amount of wear of the cutting tool when repeatedly executing the NC program, and estimates the resulting fluctuation in cutting force. The estimation device according to claim 1 .

3. The estimation device according to claim 1 , further comprising a coincidence calculation unit that calculates a coincidence between the time series data of the estimated cutting force output from the cutting force estimation unit and the time series data of the actually measured cutting force.

4. The estimation device according to claim 2 , further comprising a determination unit that determines whether the cutting force and the amount of wear estimated by the cutting force estimation unit and the wear estimation unit are outside normal ranges.

5. 5. The estimation device according to claim 1, wherein the mechanical configuration information unit calculates and updates the characteristic values ​​of the mechanical configuration information unit by using at least one set of time series data of actual measured cutting forces and time series data of estimated cutting forces output from the cutting force estimation unit.

6. 5. The estimation device according to claim 1, wherein the machine configuration information unit calculates a characteristic value representing a change in the cutting tool held by the machine configuration information unit by using at least two sets of time series data of actual cutting forces or time series data of estimated cutting forces output from the cutting force estimation unit.

7. 5. The estimation device according to claim 1, wherein the machine configuration information unit edits the NC program so as to satisfy a target cycle time by using at least one set of time series data of actual measured cutting forces or time series data of estimated cutting forces output from the cutting force estimation unit.

8. The estimation device according to claim 1 , wherein the machine configuration information unit identifies the cause of the abnormality by assigning at least one label to a combination of characteristic values ​​of the machine configuration information unit.

9. The estimation device according to claim 1 , wherein the display control unit displays at least one label provided by the machine configuration information unit in combination with a certainty factor.

10. The estimation device according to claim 2 or 4, wherein the wear estimation unit estimates a limit wear amount of the cutting tool and a time when the limit wear amount will be reached.

11. The estimation device according to claim 10 , wherein the display control unit displays the limit wear amount of the cutting tool calculated by the wear estimating unit and the time when the limit wear amount will be reached.

12. The estimation device according to claim 1 , wherein the cutting force estimation unit estimates chatter vibrations occurring in a spindle of a cutting tool, a workpiece, or both, based on a torque command output from the feedback control unit.

13. The estimation device according to claim 12 , wherein the display control unit displays the chatter vibration result calculated by the cutting force estimating unit.

14. 14. The estimation device according to claim 1, wherein the display control unit displays a cycle time of the NC program estimated based on the number of calculations required by the command generation unit for interpolation calculation of the NC program.

15. 12. The estimation device according to claim 2, wherein the display control unit displays an abnormality in the estimated value on the block diagram when at least one of the estimated cutting force estimated by the cutting force estimation unit and the amount of wear estimated by the wear estimation unit deviates from a normal range.

16. The estimation device according to claim 1 , further comprising a production line estimation unit that estimates the operation and aging of a production line by combining the estimation devices of a plurality of industrial machines.

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