Computation device, machine tool, and computation method

Abstract

This computation device comprises: a first calculation unit that calculates a first speed signal on the basis of displacement information indicating the displacement of a linear motion mechanism provided to a machine tool; a second calculation unit that calculates a second speed signal on the basis of acceleration information indicating the acceleration of the linear motion mechanism; a third calculation unit that calculates a third speed signal on the basis of the first speed signal and the second speed signal; and a state estimation unit that estimates the state of the linear motion mechanism on the basis of the third speed signal and motor information relating to a motor that drives the linear motion mechanism.

Description

Calculation device, machine tool, and calculation method

[0001] The present disclosure relates to a computing device, a machine tool, and a computing method.

[0002] Patent Document 1 discloses a cutting machine equipped with a state estimating unit that estimates the state of an actuator that applies a force to an object.

[0003] JP 2018-85058 A

[0004] It is desirable to be able to accurately estimate the state of an actuator, specifically, the state of a linear motion mechanism driven by an actuator such as a motor.

[0005] A calculation device according to one aspect of the present disclosure includes a first calculation unit that calculates a first speed signal based on displacement information indicating a displacement of a linear motion mechanism included in a machine tool, a second calculation unit that calculates a second speed signal based on acceleration information indicating an acceleration of the linear motion mechanism, a third calculation unit that calculates a third speed signal based on the first speed signal and the second speed signal, and a state estimation unit that estimates a state of the linear motion mechanism based on the third speed signal and motor information related to a motor that drives the linear motion mechanism.

[0006] Furthermore, a machine tool according to one aspect of the present disclosure includes the above-described arithmetic device, a spindle that supports a tool for machining a workpiece, a stage on which the workpiece is placed, a displacement sensor that detects the displacement of the linear motion mechanism, an acceleration sensor that detects the acceleration of the linear motion mechanism, and a display unit that displays the estimation result of the state estimation unit, wherein the linear motion mechanism is at least one of the spindle and the stage.

[0007] Furthermore, a calculation method according to one aspect of the present disclosure calculates a first velocity signal based on displacement information indicating the displacement of a linear motion mechanism provided in a machine tool, calculates a second velocity signal based on acceleration information indicating the acceleration of the linear motion mechanism, calculates a third velocity signal based on the first velocity signal and the second velocity signal, and estimates a state of the linear motion mechanism based on motor information related to a motor that drives the linear motion mechanism and the third velocity signal.

[0008] According to the computing device according to one aspect of the present disclosure, the state of the linear motion mechanism can be estimated with high accuracy.

[0009] FIG. 1 is a block diagram showing the configuration of a calculation device according to an embodiment. FIG. 2 is a schematic diagram showing the configuration of a machine tool according to an embodiment. FIG. 3 is a block diagram showing a specific example of the configuration of a calculation device according to an embodiment. FIG. 4 is a diagram showing a first example of the change in speed of a linear motion mechanism over time. FIG. 5 is a diagram showing a first example of the change in cutting resistance acting on a linear motion mechanism over time. FIG. 6 is a diagram showing a second example of the change in speed of a linear motion mechanism over time. FIG. 7 is a diagram showing a second example of the change in cutting resistance acting on a linear motion mechanism over time. FIG. 8 is a schematic diagram showing a modified example of the configuration of a machine tool according to an embodiment. FIG. 9 is a block diagram showing a modified example of the configuration of a calculation device according to an embodiment. FIG. 10 is a flowchart showing a calculation method according to an embodiment.

[0010] (Findings Forming the Basis of the Present Disclosure) Conventionally, there have been machine tools (i.e., processing machines) equipped with linear motion mechanisms, such as a spindle to which a tool is attached that performs machining, such as cutting, on a workpiece (also referred to as an object) to be machined, and a stage on which the workpiece is placed. When a workpiece is machined using a machine tool, if the machining conditions are inappropriate, the quality of the machined surface of the workpiece deteriorates. For example, if the machining conditions are inappropriate during cutting using a machine tool, vibrations occur due to cutting resistance (i.e., cutting force) that changes intermittently during cutting, resulting in unstable cutting and deterioration of the quality of the machined surface. Therefore, it is desirable to be able to accurately measure the state of the linear motion mechanism, such as cutting resistance, which is a cause of such vibration, under various machining conditions. If the state of the linear motion mechanism, such as the cutting resistance acting on the linear motion mechanism, can be accurately measured, the location and timing of vibration occurrence can be accurately identified. Furthermore, machining conditions and machining positions can be linked to the location and timing of vibrations generated during machining. Furthermore, it is possible to easily identify areas where the machining conditions are inappropriate. Furthermore, it is possible to monitor deterioration over time of the machine tool, such as machine wear. This makes it easier to visualize the processing quality of the workpiece.

[0011] Conventionally, cutting resistance has generally been measured using sensors such as dynamometers, but such sensors are expensive and have the problem of reducing the rigidity of the machine tool.

[0012] Therefore, there is a method for estimating cutting resistance without using a dynamometer, by using a control command output to a motor or the like when a machine tool drives a linear motion mechanism or the like during cutting, information about the motor, information about the spindle, and information about the stage on which the workpiece is placed.For example, the above-mentioned Patent Document 1 discloses a cutting device that estimates the state of an actuator based on the equation of motion of an inertia model of the actuator, using parameters that represent internal information about the actuator that applies force to an object.

[0013] Here, to calculate an equation of motion from internal information of an actuator such as a motor that drives a stage, the velocity of the stage is required. The velocity is calculated, for example, by differentiating the change in the position of the stage over time. In this case, if the velocity is calculated using, for example, a differentiator that performs differentiation, noise in the high-frequency band (high-frequency components) increases. Therefore, to filter (cut) such noise, signal processing using a low-pass filter or the like is required. However, when such signal processing is performed, frequency components necessary for calculating the velocity are also filtered, resulting in a decrease in the accuracy of high-frequency components when estimating the state of the actuator.

[0014] As a result of investigations, the inventors of the present application have discovered a computing device and the like that can accurately estimate the state of an actuator, more specifically, the state of a linear motion mechanism driven by a motor.

[0015] Hereinafter, the embodiments will be specifically described with reference to the drawings.

[0016] The embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, component placement and connection configurations, steps, and step order shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Furthermore, among the components in the following embodiments, components not described in the independent claims are described as optional components.

[0017] In this specification and drawings, the X-axis, Y-axis, and Z-axis represent the three axes of a three-dimensional Cartesian coordinate system. The Z-axis is, for example, the vertical direction. For example, the positive and negative sides of the Z-axis direction are up (upward direction) and down (downward direction), respectively.

[0018] Furthermore, in this specification, ordinal numbers such as "first" and "second" do not refer to the number or order of components unless otherwise specified, but are used for the purpose of avoiding confusion and distinguishing between components of the same type.

[0019] Furthermore, in this specification, when a comparison is made, for example, with "above a threshold" or "below a threshold," it means that the distinction is made at the threshold, and may mean "greater than the threshold" or "below the threshold," respectively.

[0020] (Embodiment) [Configuration] FIG. 1 is a block diagram showing the configuration of a computing device 100 according to an embodiment.

[0021] The arithmetic device 100 is a computer used in a machine tool that processes a workpiece, and estimates the state of the linear motion mechanism 400 provided in the machine tool. Specifically, the arithmetic device 100 estimates (calculates) the cutting resistance acting on the linear motion mechanism 400 driven by a motor when the machine tool cuts the workpiece.

[0022] The linear motion mechanism 400 is a mechanism driven by an actuator such as a motor when a machine tool processes a workpiece. The linear motion mechanism 400 is, for example, a spindle to which a tool for processing the workpiece is attached, and a stage on which the workpiece is placed. The motor that drives the linear motion mechanism 400, for example, drives the spindle, which is an example of a linear motion mechanism, to move or rotate the tool supported by the spindle. Furthermore, for example, the motor moves the workpiece by moving a stage, which is another example of a linear motion mechanism.

[0023] The arithmetic device 100 is realized by a computer including, for example, a communication interface for communicating with a motor or the like provided in the machine tool, a non-volatile memory for storing programs executed by each processing unit, a volatile memory that is a temporary storage area for executing the programs, an input / output port for sending and receiving signals, and a processor such as a CPU (Central Processing Unit) that executes the programs. The communication interface may be realized by a connector to which a communication line is connected for wired communication, or by a wireless communication circuit for wireless communication.

[0024] The arithmetic device 100 includes a calculation unit 200 and a state estimation unit 300 .

[0025] The calculation unit 200 is a processing unit that calculates the speed of the linear motion mechanism 400. The calculation unit 200 includes a first calculation unit 210, a second calculation unit 220, and a third calculation unit 230.

[0026] The first calculator 210 is a processing unit that calculates the velocity of the linear motion mechanism 400 based on displacement information indicating the displacement of the linear motion mechanism 400 (more specifically, the change in the position of the linear motion mechanism 400 over time). The velocity calculated based on the displacement information is also referred to as a first velocity signal. The first calculator 210 is realized, for example, by a circuit such as a differentiator that differentiates the displacement information. The first calculator 210 may also be realized by a memory and a processor that executes a control program stored in the memory. The first calculator 210, for example, acquires displacement information from a sensor that detects the displacement (position) of the linear motion mechanism 400, and calculates (generates) the first velocity signal based on the acquired displacement information.

[0027] The second calculation unit 220 is a processing unit that calculates the velocity of the linear motion mechanism 400 based on acceleration information indicating the acceleration of the linear motion mechanism 400 (more specifically, the change in acceleration of the linear motion mechanism 400 over time). The velocity calculated based on the acceleration information is also referred to as a second velocity signal. The second calculation unit 220 is realized, for example, by a circuit such as an integrator that integrates the acceleration information. The second calculation unit 220 may also be realized by a memory and a processor that executes a control program stored in the memory. The second calculation unit 220, for example, acquires acceleration information from a sensor that detects the acceleration of the linear motion mechanism 400, and calculates (generates) the second velocity signal based on the acquired acceleration information.

[0028] The third calculation unit 230 is a processing unit that calculates the velocity of the linear motion mechanism 400 based on the first velocity signal and the second velocity signal. The velocity calculated from the first velocity signal and the second velocity signal is also referred to as the third velocity signal. In other words, the third velocity signal is calculated based on the displacement information and the acceleration information. The third calculation unit 230 is realized, for example, by a circuit such as an adder that adds the first velocity signal and the second velocity signal. The third calculation unit 230 may also be realized by a memory and a processor that executes a control program stored in the memory. For example, the third calculation unit 230 acquires the first velocity signal from the first calculation unit 210 and the second velocity signal from the second calculation unit 220, and calculates (generates) the third velocity signal based on the acquired first velocity signal and the acquired second velocity signal.

[0029] In this way, the calculation unit 200 calculates the velocity of the linear motion mechanism 400 (i.e., the third velocity signal) based on the displacement information and acceleration information of the linear motion mechanism 400 .

[0030] As described above, when velocity is calculated by differentiating displacement, noise in the high frequency band increases. On the other hand, when velocity is calculated by integrating acceleration, drift occurs due to integration error. Therefore, the calculation unit 200 calculates the third velocity signal, which is the velocity of the linear motion mechanism 400, using, for example, the low frequency band of the first velocity signal and the high frequency band of the second velocity signal. This allows the velocity of the linear motion mechanism 400 to be calculated with high accuracy.

[0031] For example, the first velocity signal may be calculated using displacement information whose high frequency band has been filtered by a low-pass filter or the like. Furthermore, for example, the first velocity signal whose high frequency band has been filtered by a low-pass filter or the like may be output to the third calculation unit 230. Furthermore, for example, the second velocity signal may be calculated using acceleration information whose low frequency band has been filtered by a high-pass filter or the like. Furthermore, for example, the second velocity signal whose low frequency band has been filtered by a high-pass filter or the like may be output to the third calculation unit 230. Furthermore, the first calculation unit 210, the second calculation unit 220, or the third calculation unit 230 may delete the high frequency band of the first velocity signal and the low frequency band of the second velocity signal by computer processing or the like.

[0032] Furthermore, for example, the calculation unit 200 acquires motor information related to the motor that drives the linear motion mechanism 400 from the linear motion mechanism 400 or the like, and outputs the acquired motor information and the third speed signal to the state estimation unit 300. Note that the motor information may be output from the calculation unit 200, from a device included in the linear motion mechanism 400, from a control device that controls the machine tool, from a server, or from a storage device such as a semiconductor memory or an HDD (Hard Disk Drive). The storage device may be included in the calculation device 100.

[0033] The motor information is information related to the motor that drives linear motion mechanism 400. The motor information includes, for example, current information indicating the input current to the motor, or motor rotation information indicating the rotation angle of the motor. The motor information may also include information indicating an instruction to drive the motor (also referred to as a control command), which is output from a control device that controls machine tool 10 to the motor, etc.

[0034] The state estimation unit 300 is a processing unit that estimates the state of the linear motion mechanism 400 based on the motor information and the third speed signal. The state of the linear motion mechanism 400 is estimated from the speed accurately calculated by the calculation unit 200, thereby accurately calculating the state of the linear motion mechanism 400. The estimation result of the state estimation unit 300 (i.e., the state of the linear motion mechanism 400) is output to a display device such as a monitor. By displaying the estimation result on the display device, for example, an operator of the machine tool 10 can confirm the state of the linear motion mechanism 400. The state estimation unit 300 is realized by, for example, a memory and a processor that executes a control program stored in the memory.

[0035] As described above, the arithmetic device 100 includes a first calculation unit 210 that calculates a first velocity signal based on displacement information indicating the displacement of the linear motion mechanism 400 provided in the machine tool, a second calculation unit 220 that calculates a second velocity signal based on acceleration information indicating the acceleration of the linear motion mechanism 400, a third calculation unit 230 that calculates a third velocity signal based on the first velocity signal and the second velocity signal, and a state estimation unit 300 that estimates the state of the linear motion mechanism 400 based on the third velocity signal and motor information related to the motor that drives the linear motion mechanism 400.

[0036] This allows for accurate calculation of the speed of the linear motion mechanism 400. Therefore, the state of the linear motion mechanism 400 can be estimated using the accurately calculated speed of the linear motion mechanism 400, and therefore the state of the linear motion mechanism 400 can be estimated with high accuracy.

[0037] Next, a machine tool equipped with a computing device will be described.

[0038] Fig. 2 is a schematic diagram showing the configuration of machine tool 10 according to the embodiment. Fig. 3 is a block diagram showing the configuration of arithmetic device 101. Arithmetic device 101 is a specific example of arithmetic device 100.

[0039] The machine tool 10 is a processing machine that performs processing on the workpiece 20. In the present embodiment, the machine tool 10 performs cutting processing (also simply referred to as cutting) on ​​the workpiece 20.

[0040] Machine tool 10 includes machine tool control unit 11, tool 30, spindle 40, stage 50, motors 60, 61, 62, and 63, sensors 70, 71, and 72, servo amplifiers 80, 81, and 82, and inverter 90. Workpiece 20, which is the object to be cut by machine tool 10, is placed on stage 50. Workpiece 20 is fixed on stage 50, for example.

[0041] The main shaft 40 and the stage 50 are each an example of the linear motion mechanism 400. In other words, the linear motion mechanism 400 is at least one of the main shaft 40 and the stage 50.

[0042] Machine tool control unit 11 is a control device that controls the components of machine tool 10. Machine tool control unit 11 is realized by a computer that includes, for example, a communication interface for communicating with servo amplifiers that control motors provided in machine tool 10, non-volatile memory that stores programs executed by each processing unit, volatile memory that is a temporary storage area for executing the programs, input / output ports for sending and receiving signals, and a processor such as a CPU that executes the programs. The communication interface may be realized by a connector to which a communication line is connected for wired communication, or by a wireless communication circuit for wireless communication.

[0043] The machine tool control unit 11 includes a command unit 500, a calculation device 101, and a display unit 600. The calculation device 101 includes a calculation unit 201 and a state estimation unit 300.

[0044] Command unit 500 is a processing unit that controls each device included in machine tool 10 so that tool 30 cuts workpiece 20. In this example, command unit 500 determines the operation of spindle 40 and stage 50, and outputs control commands to servo amplifiers 80, 81, and 82 and inverter 90 to execute the determined operation. The control commands include information indicating, for example, the positions and speeds of spindle 40 and stage 50 in the X-axis, Y-axis, and Z-axis directions, the rotation speed of spindle 40, and a torque command. Command unit 500 is realized, for example, by a memory and a processor that executes a control program stored in the memory.

[0045] The command unit 500 controls the position of at least one of the tool 30, the spindle 40, and the stage 50, for example, so that the tool 30 is positioned to cut the workpiece 20. For example, the command unit 500 outputs a control command to the servo amplifier 80, thereby controlling the position of the spindle 40 by the motor 61 so that the tool 30 is positioned at an appropriate position in the Z-axis direction. The command unit 500 also outputs a control command to the servo amplifiers 81 and 82, thereby controlling the position of the stage 50 by the motors 62 and 63. For example, the command unit 500 outputs a control command to the servo amplifier 81, thereby controlling the position of the stage 50 so that the workpiece 20 moves at an appropriate speed toward the negative side of the X-axis direction. In other words, the command unit 50 moves the stage 50 at an appropriate speed toward the negative side of the X-axis direction. The command unit 500 also controls the inverter 90 to control the rotational speeds of the spindle 40 and the tool 30 so that the tool 30 cuts the workpiece 20. Through the above-described processing, the tool 30 processes (specifically, cuts) the workpiece.

[0046] The calculation unit 201 is a processing unit that calculates the velocity of the stage 50 based on displacement information that indicates the displacement of the stage 50 and acceleration information that indicates the acceleration of the stage 50. In this example, the calculation unit 201 acquires motor information and sensor information from the servo amplifier 82 that controls the motor 63 that drives the stage 50, and calculates the velocity of the stage 50 based on the acquired motor information and sensor information.

[0047] The sensor information includes acceleration information that indicates the acceleration of the stage 50 detected by the sensor 70 and displacement information that indicates the displacement of the stage 50 detected by the sensor 71 .

[0048] The calculation unit 201 includes a first calculation unit 210A, a second calculation unit 220A, and an adder 231. The first calculation unit 210A includes a differentiator 211 and a first filter unit 212. The second calculation unit 220A includes an integrator 221 and a second filter unit 222. The adder 231 is a specific example of the third calculation unit 230.

[0049] The differentiator 211 is a differentiation circuit for calculating (generating) a first velocity signal by differentiating input information. In this example, the differentiator 211 calculates the first velocity signal by differentiating the displacement information.

[0050] The first filter unit 212 is a filter circuit for filtering noise in the input information. In this example, the first filter unit 212 filters noise in the first speed signal calculated by the differentiator 211. Specifically, the first filter unit 212 filters at least a part of the frequency band of the first speed signal calculated by the differentiator 211, thereby filtering noise in the first speed signal.

[0051] The integrator 221 is an integration circuit for calculating (generating) a second velocity signal by integrating input information. In this example, the integrator 221 calculates the second velocity signal by integrating acceleration information.

[0052] The second filter unit 222 is a filter circuit for filtering noise in the input information. In this example, the second filter unit 222 filters noise in the second speed signal calculated by the integrator 221. Specifically, the second filter unit 222 filters at least a part of the frequency band of the second speed signal calculated by the integrator 221, thereby filtering noise in the second speed signal.

[0053] Here, the first filter unit 212 and the second filter unit 222 have different filter characteristics. Specifically, the first filter unit 212 and the second filter unit 222 filter different frequency bands. For example, the first filter unit 212 filters a high-frequency band, and the second filter unit 222 filters a low-frequency band. That is, for example, the first filter unit 212 is a low-pass filter, and the second filter unit 222 is a high-pass filter.

[0054] The frequency bands filtered by the first filter unit 212 and the second filter unit 222 may be determined arbitrarily. For example, the first filter unit 212 is a low-pass filter, and the second filter unit 222 is a high-pass filter. The filter characteristics of the first filter unit 212 and the second filter unit 222 are determined so that the cutoff frequencies of the first filter unit 212 and the second filter unit 222 are the same. For example, the cutoff frequencies of the first filter unit 212 and the second filter unit 222 are each determined to be 40 Hz. As a result, for example, the first filter unit 212 removes a frequency band equal to or greater than the cutoff frequency. Furthermore, for example, the second filter unit 222 removes a frequency band below the cutoff frequency. For example, the first filter section 212 is a low-pass filter, the second filter section 222 is a high-pass filter, and the cutoff frequencies of the first filter section 212 and the second filter section 222 are determined to be the same frequency, thereby calculating a third velocity signal including information of the entire frequency band from the displacement information and acceleration information.

[0055] Furthermore, the first filter unit 212 may be a band-stop filter, and the second filter unit 222 may be a band-pass filter. By determining that the frequency band filtered by the first filter unit 212 and the frequency band extracted by the second filter unit 222 match, noise is appropriately filtered out and a third velocity signal including information of a wide frequency band is calculated.

[0056] The adder 231 is an adder circuit that calculates (generates) a third velocity signal (stage velocity shown in FIG. 3 ) based on the first velocity signal filtered by the first filter unit 212 and the second velocity signal filtered by the second filter unit 222.

[0057] As described above, in the arithmetic device 101, the first calculation unit 210A includes a differentiator 211 that calculates a first velocity signal by differentiating the displacement information, and a first filter unit 212 that filters noise from the first velocity signal calculated by the differentiator 211; the second calculation unit 220A includes an integrator 221 that calculates a second velocity signal by integrating acceleration information, and a second filter unit 222 that has filter characteristics different from those of the first filter unit 212 and filters noise from the second velocity signal; and the third calculation unit (specifically, adder 231) calculates a third velocity signal based on the first velocity signal filtered by the first filter unit 212 and the second velocity signal filtered by the second filter unit 222.

[0058] This allows the state of the linear motion mechanism 400 (in this example, the stage 50) to be calculated with high accuracy.

[0059] As described above, state estimation unit 300 estimates the state of linear motion mechanism 400 based on the third speed signal and motor information related to the motor that drives linear motion mechanism 400. Specifically, state estimation unit 300 estimates, as the state of linear motion mechanism 400, the force (cutting resistance) that workpiece 20 exerts on linear motion mechanism 400 when tool 30 included in machine tool 10 cuts workpiece 20.

[0060] This allows the state estimation unit 300 to accurately estimate the cutting resistance acting on the linear motion mechanism 400 .

[0061] In this example, the state estimation unit 300 estimates the force (cutting resistance) acting on the stage 50 based on the third speed signal (stage speed) and motor information related to the motor 63 that drives the stage 50. Specifically, the state estimation unit 300 estimates the cutting resistance acting on the stage 50 based on the motor information (specifically, information indicating the rotation angle of the motor 63) and the speed of the stage 50 calculated by the calculation unit 201.

[0062] Estimation of cutting resistance is disclosed, for example, in the above-mentioned Patent Document 1. For example, cutting resistance can be calculated by the following formula.

[0063]

[0064] In addition, Mｒ is the mass calculated from the total moment of inertia including the components such as the ball screw for driving (moving) the stage 50, including the motor 63. ｔ is the total mass of the stage 50 and the workpiece 20. ｒ is the damping coefficient of the motor 63. ｋ is the damping coefficient of the damping component (dashpot) that exists between the rotational system and the translational system. C ｔ is the damping coefficient of the translational system. ｔ is the torque constant of the motor 63. ｒ is the stiffness of the spring component that exists between the rotational system and the translational system. R is the conversion factor between the rotational system and the translational system. I ａ is the current applied to the motor 63. ｍ is the acceleration calculated from the rotation angle of the motor 63. ｔ is the acceleration of the stage 50 detected by the sensor 70. ｍ is the speed calculated from the rotation angle of the motor 63. ｔ is the velocity of the stage 50. ｍ is the position of the stage 50 calculated from the rotation angle of the motor 63. ｔ is the position of the stage 50 detected by the sensor 71. ｃｕｔ is the cutting force of the tool 30 on the workpiece 20. Specifically, the cutting resistance is the same magnitude as the cutting force, which is the force exerted on the workpiece 20 by the tool 30 that is cutting the workpiece 20, and is a force in the opposite direction to the cutting force. ｃｕｔ is the cutting resistance acting on the tool 30. In this example, the tool 30 is fixed to the spindle 40. The workpiece 20 is fixed to the stage 50. Therefore, the spindle 40 and the stage 50 are also subjected to -F ｃｕｔ A cutting resistance of

[0065] The third velocity signal (stage velocity) calculated by the calculation unit 201 is expressed as v ｔ It is. ｔ By accurately calculating -F ｃｕｔ is calculated with high accuracy.

[0066] FIG. 4 is a diagram showing a first example of the change in the velocity of the linear motion mechanism 400 (specifically, the stage 50) over time. FIG. 5 is a diagram showing a first example of the change in the cutting resistance acting on the linear motion mechanism 400 (specifically, the stage 50) over time. The dashed lines shown in FIGS. 4 and 5 represent simulation results (ideal waveforms) when noise is not included. The solid lines shown in FIGS. 4 and 5 represent simulation results (observed waveforms) when noise is included. FIG. 5 is a graph showing the simulation results of the change in the cutting resistance acting on the stage 50 over time, calculated using the velocity signal indicating the velocity of the stage 50, which is the simulation result shown in FIG. 4. The horizontal axis in FIG. 4 represents time, and the vertical axis represents velocity. The horizontal axis in FIG. 5 represents time, and the vertical axis represents cutting resistance.

[0067] The solid line in Fig. 4 represents the results of a simulation calculated using only the displacement information of the stage 50 when noise in the same frequency band as the rotational speed of the spindle 40 is superimposed on the output of the sensor 72 (i.e., the output of the servo amplifier 82). The solid line in Fig. 5 is a graph showing the results of a simulation of the time change in the speed of the stage 50 calculated by differentiating this displacement information. The simulations used to obtain the results of the solid and dashed lines were performed under the same conditions, except for the presence or absence of noise. For example, the rotational speed and frequency of the spindle 40 are 10,000 rpm and 167 Hz.

[0068] As shown in Fig. 4, the amplitude of the observed waveform of the velocity of the stage 50 is much smaller than the amplitude of the ideal waveform. In other words, when noise is present, the amplitude of the velocity is much smaller than when noise is not present. Therefore, as shown in Fig. 5, the amplitude of the observed waveform of the cutting resistance exerted by the workpiece 20 on the stage 50 is much smaller than the amplitude of the ideal waveform.

[0069] FIG. 6 is a diagram showing a second example of the change in the velocity of the linear motion mechanism 400 (specifically, the stage 50) over time. FIG. 7 is a diagram showing a second example of the change in the cutting resistance acting on the linear motion mechanism 400 (specifically, the stage 50) over time. The dashed lines shown in FIGS. 6 and 7 represent simulation results (ideal waveforms) when noise is not included. The solid lines shown in FIGS. 6 and 7 represent simulation results (observed waveforms) when noise is included. FIG. 7 is a graph showing simulation results of the change in the cutting resistance acting on the stage 50 over time, calculated using the velocity signal indicating the velocity of the stage 50, which is the simulation result shown in FIG. 6. The horizontal axis in FIG. 6 represents time, and the vertical axis represents velocity. The horizontal axis in FIG. 7 represents time, and the vertical axis represents cutting resistance.

[0070] The solid line in Figure 6 represents the results of a simulation calculated using displacement information of the stage 50 when noise in the same frequency band as the rotation speed of the spindle 40 is superimposed on the output of sensor 72, and acceleration information of the stage 50 when noise in the same frequency band as the rotation speed of the spindle 40 is superimposed on the output of sensor 70. The solid line in Figure 6 is a graph showing the results of a simulation of the time change of the stage 50 calculated using the velocity of the stage 50 calculated by differentiating the displacement information and the velocity of the stage 50 calculated by integrating the acceleration information. The simulations used to obtain the results of the solid and dashed lines were conducted under the same conditions, except for the presence or absence of noise. For example, the rotation speed and frequency of the spindle 40 are 10,000 rpm and 167 Hz, respectively.

[0071] As shown in Fig. 6, compared to the simulation results of Fig. 4, the velocity of the stage 50 is similar between the ideal waveform and the observed waveform. In other words, by calculating the velocity of the stage 50 using the displacement information and acceleration information, similar values ​​can be calculated whether noise is included or not. Therefore, as shown in Fig. 7, the cutting resistance exerted by the workpiece 20 on the stage 50 can be calculated as an observed waveform that is close to the ideal waveform.

[0072] In this way, the calculation unit 201 calculates the speed using the displacement information and the acceleration information, so the speed is calculated with high accuracy, and the state estimation unit 300 can therefore calculate the cutting resistance with high accuracy.

[0073] Referring again to FIG. 2, each of the components of the machine tool 10 will be described.

[0074] The display unit 600 is a display that displays various types of information. For example, the display unit 600 displays the estimation results of the state estimation unit 300. The display unit 600 also displays, for example, predetermined setting information for controlling the rotation angles of the motors 60, 61, 62, and 63, information indicating each control command output by the command unit 500, displacement information, acceleration information, and motor information output from the servo amplifiers 80, 81, and 82, parameters related to sensor information, and the like.

[0075] The tool 30 is a tool that processes the workpiece 20. Specifically, the tool 30 performs processing such as removal processing on the workpiece 20, which is the object to be processed. In this embodiment, the tool 30 is a tool that cuts the workpiece 20. The tool 30 is supported by the spindle 40 so as to be rotatable about a rotation axis parallel to the Z axis. The rotating tool 30 comes into contact with the workpiece 20, thereby cutting the workpiece 20. Furthermore, the stage 50 moves in the X-axis and Y-axis directions while the position of the tool 30 in the Z-axis direction is constant, thereby cutting the workpiece 20. Note that the tool 30 is, for example, an end mill, but may also be a drill or the like. Furthermore, the state of the linear motion mechanism 400 estimated by the state estimation unit 300 is, for example, cutting resistance, but may also be cutting resistance or the like.

[0076] The spindle 40 rotatably supports the tool 30. Specifically, the spindle 40 has a jig such as a chuck for gripping the tool 30, and grips the tool 30 using the jig. The spindle 40 also rotates (in other words, spins) the tool 30 around a pivot axis parallel to the Z axis. The rotation speed is, for example, about 1000 rpm to 40000 rpm, but is not limited to this.

[0077] The stage 50 is a stage on which the workpiece 20 is placed. The stage 50 is movable horizontally, that is, in the X-axis direction and the Y-axis direction, and the position of the stage 50 in at least one of the X-axis direction and the Y-axis direction is changed by driving at least one of the motors 62 and 63. The workpiece 20 is fixed on the stage 50, and moves as the stage 50 moves.

[0078] The motor 60 is a motor that drives the main shaft 40 to rotate.

[0079] The motor 61 drives (moves) the spindle 40 in the height direction (Z-axis direction).

[0080] The motor 62 drives (moves) the stage 50 in the Y-axis direction.

[0081] The motor 63 drives (moves) the stage 50 in the feed axis direction (X axis direction).

[0082] The sensor 70 is an acceleration sensor that detects the acceleration of the stage 50. The sensor 70 is an example of an acceleration sensor.

[0083] The sensor 71 is a sensor that detects the displacement (amount of movement) of the stage 50. The sensor 71 is realized by, for example, a linear scale and a detection head. The sensor 71 is an example of a displacement sensor.

[0084] The sensor 72 is a sensor that detects the rotation angle of the motor 63. The sensor 72 outputs information indicating the detected rotation angle of the motor 63 to the servo amplifier 82. Note that the motors 61 and 62 are equipped with sensors that detect the rotation angles of the motors 61 and 62. The detection results of the sensors are output to the servo amplifiers 80 and 81, for example.

[0085] The servo amplifier 80 is a controller that controls the driving of the motor 61 .

[0086] The servo amplifier 81 is a controller that controls the driving of the motor 62 .

[0087] The servo amplifier 82 is a controller that controls the driving of the motor 63 .

[0088] Servo amplifiers 80, 81, and 82 each acquire a control command from command unit 500 and control motors 61, 62, and 63 based on the acquired control command. Servo amplifiers 80, 81, and 82 also output information indicating the rotation angles of motors 61, 62, and 63, which is an example of motor information acquired from motors 61, 62, and 63, to machine tool control unit 11. Servo amplifier 82 also outputs the detection results of sensors 70 and 71 (specifically, displacement information and acceleration information) to machine tool control unit 11 as sensor information.

[0089] The command unit 500 controls the motors 61 , 62 , and 63 based on information obtained from the servo amplifiers 80 , 81 , and 82 , that is, while receiving feedback from the servo amplifiers 80 , 81 , and 82 .

[0090] Inverter 90 is an inverter that controls the driving of motor 60. Inverter 90 acquires information indicating the rotation speed of spindle 40 from command unit 500, and controls motor 60 based on the acquired information. In addition, inverter 90 outputs information indicating the rotation speed of spindle 40 acquired from motor 60 to machine tool control unit 11. Command unit 500 controls the rotation speed of spindle 40 based on the information indicating the rotation speed of spindle 40 acquired from motor 60, that is, while receiving feedback from motor 60 (spindle rotation speed control shown in FIG. 2 ).

[0091] As described above, machine tool 10 includes arithmetic device 101, spindle 40 that supports tool 30 that machines workpiece 20, stage 50 on which workpiece 20 is placed, a displacement sensor that detects the displacement of the linear motion mechanism, an acceleration sensor that detects the acceleration of the linear motion mechanism, and display unit 600 that displays the estimation result of state estimation unit 300, and the linear motion mechanism is at least one of spindle 40 and stage 50. In this example, the displacement sensor is sensor 71, the acceleration sensor is sensor 70, and the linear motion mechanism is stage 50.

[0092] This allows the state of at least one of the spindle 40 and the stage 50, which is the state of the linear motion mechanism estimated with high accuracy by the computing device 101, to be displayed on the display unit 600. This makes it easier for the operator operating the machine tool 10 to check the state of at least one of the spindle 40 and the stage 50.

[0093] The configuration of the machine tool is not limited to the above. For example, the arithmetic unit may be provided in a servo amplifier.

[0094] 8 is a schematic diagram showing the configuration of a machine tool 10A. The machine tool 10A is a modified example of the machine tool 10.

[0095] The machine tool 10A includes a machine tool control unit 11A, a tool 30, a spindle 40, a stage 50, motors 60, 61, 62 and 63, sensors 70, 71 and 72, servo amplifiers 80, 81 and 82A, and an inverter 90.

[0096] The machine tool control unit 11A is a control device that controls the components of the machine tool 10. The machine tool control unit 11A includes a command unit 500.

[0097] The servo amplifier 82A is a controller that controls the driving of the motor 63. Furthermore, in this example, the servo amplifier 82A calculates the speed of the stage 50 based on displacement information indicating the displacement of the stage 50 and acceleration information indicating the acceleration of the stage 50, and calculates the cutting resistance that the workpiece 20 exerts on the stage 50 based on the calculation result. For example, the servo amplifier 82A includes a configuration for controlling the driving of the motor 63, a computing device 101, and a display unit 600. In this example, the computing device 101 acquires displacement information (specifically, stage displacement) from the sensor 70 and acceleration information (specifically, stage acceleration) from the sensor 71.

[0098] In this way, the function of calculating the speed of stage 50 and the cutting resistance exerted by workpiece 20 on stage 50 may be arranged in any of the components of the machine tool. Also, display unit 600 may be arranged in any of the components of the machine tool. Also, each component of the machine tool may be connected to any other component so that various information can be communicated with the other component so that motor information, sensor information, etc. can be output to the arithmetic device.

[0099] Furthermore, the configuration of the arithmetic unit is not limited to the above. For example, in the arithmetic unit, the displacement information and acceleration information of the linear motion mechanism 400 may be filtered by a filter unit, and then differentiated or integrated to calculate the velocity.

[0100] 9 is a block diagram showing the configuration of the arithmetic device 102. The arithmetic device 102 is a modified example of the arithmetic device 101.

[0101] The calculation device 102 includes a calculation unit 202 and a state estimation unit 300 .

[0102] The calculation unit 202 is a processing unit that calculates the velocity of the stage 50 based on displacement information indicating the displacement of the stage 50 and acceleration information indicating the acceleration of the stage 50 .

[0103] The calculation unit 202 includes a first calculation unit 210B, a second calculation unit 220B, and an adder 231. The first calculation unit 210B includes a first filter unit 212 and a differentiator 211. The second calculation unit 220B includes a second filter unit 222 and an integrator 221.

[0104] In this example, the first filter unit 212 filters noise from the displacement information (e.g., stage displacement). Specifically, the first filter unit 212 removes noise from the displacement information by filtering at least a part of the frequency band (e.g., the above-mentioned high-frequency band) of the displacement information.

[0105] In this example, the differentiator 211 calculates (generates) a first velocity signal by differentiating the displacement information filtered by the first filter unit 212 .

[0106] In this example, the second filter unit 222 filters noise from the acceleration information (e.g., stage acceleration). Specifically, the second filter unit 222 filters at least a part of the frequency band of the acceleration information (e.g., the above-mentioned low frequency band) to remove noise from the acceleration information.

[0107] In addition, in this example, the integrator 221 calculates (generates) a second velocity signal by integrating the acceleration information filtered by the second filter unit 222 .

[0108] In this way, there is no particular limitation on the order in which the first filter unit 212 and the differentiator 211 process information, and there is no particular limitation on the order in which the second filter unit 222 and the integrator 221 process information.

[0109] As described above, in the arithmetic device 102, the first calculation unit 210B includes a first filter unit 212 that filters noise in the displacement information and a differentiator 211 that calculates a first velocity signal by differentiating the displacement information filtered by the first filter unit 212, and the second calculation unit 220B includes a second filter unit 222 that filters noise in the acceleration information and has filter characteristics different from those of the first filter unit 212, and an integrator 221 that calculates a second velocity signal by integrating the acceleration information filtered by the second filter unit 222.

[0110] This allows the arithmetic unit 102 to accurately calculate the speed of the linear motion mechanism.

[0111] In the above description, the stage velocity and motor information are output from the calculation units 201 and 202 to the state estimation unit 300. The motor information includes, for example, information indicating the rotation angle of the motor 63. The motor information may also include, for example, information indicating an input current (specifically, a current value) to the motor 63 for driving the motor 63. The motor information may also include at least one of current information indicating the input current to the motor 63 and motor rotation information indicating the rotation angle of the motor 63. In other words, for example, the state estimation unit 300 estimates the state of the stage 50 based on the third velocity signal and the current information indicating the input current to the motor 63 or the motor rotation information indicating the rotation angle of the motor 63, which are included in the motor information.

[0112] In the above description, the motor information used by state estimation unit 300 for estimation is, for example, information indicating the rotation angle of each motor detected by a sensor provided in motors 61, 62, and 63, such as sensor 72. The motor information used by state estimation unit 300 for estimation may also be information indicating a control command for controlling motors 61, 62, and 63 (specifically, a control command output by command unit 500).

[0113] Furthermore, when the linear motion mechanism 400 is the spindle 40, the machine tool may be provided with an acceleration sensor that detects the acceleration of the spindle 40 and a displacement sensor that detects the displacement of the spindle.

[0114] 10 is a flowchart showing a calculation method according to an embodiment. For example, the calculation device includes a processor and a memory, and the processor performs the following processing using the memory. The calculation device is, for example, calculation device 100, 101, or 102.

[0115] First, the arithmetic device acquires displacement information indicating the displacement of a linear motion mechanism included in the machine tool and acceleration information indicating the acceleration of the linear motion mechanism (S10). The machine tool is, for example, machine tool 10 or 10A. The linear motion mechanism is, for example, linear motion mechanism 400, and specifically, at least one of spindle 40 and stage 50. The arithmetic device acquires, for example, displacement information indicating the displacement detected by a displacement sensor (e.g., sensor 71) included in the machine tool. The arithmetic device also acquires, for example, acceleration information indicating the acceleration detected by an acceleration sensor (e.g., sensor 70) included in the machine tool.

[0116] Next, the calculation device calculates a first velocity signal based on the displacement information indicating the displacement of the linear motion mechanism (S20). For example, the calculation device uses the displacement information to filter out high frequency band noise and calculate the first velocity signal.

[0117] Next, the calculation device calculates a second velocity signal based on acceleration information indicating the acceleration of the linear motion mechanism (S30). For example, the calculation device uses the acceleration information to filter out low-frequency noise and calculate the second velocity signal.

[0118] Note that step S20 and step S30 may be performed first, step S20 may be performed first, step S30 may be performed first, or they may be performed simultaneously.

[0119] Next, the calculation device calculates a third speed signal based on the first speed signal and the second speed signal (S40). For example, the calculation device calculates the third speed signal by adding the first speed signal and the second speed signal.

[0120] Next, the calculation device estimates the state of the linear motion mechanism based on the motor information related to the motor (for example, at least one of the motors 62 and 63) that drives the linear motion mechanism and the third speed signal (S50).

[0121] Next, the calculation device outputs the estimation result of the state of the linear motion mechanism (S60). For example, the calculation device outputs the estimation result to the display unit 600, thereby causing the display unit 600 to display the estimation result.

[0122] (Effects, etc.) Below, examples of techniques that can be obtained from the disclosure of this specification will be given, and effects, etc. that can be obtained from these techniques will be described.

[0123] Technique 1 is a computing device including: a first calculation unit that calculates a first speed signal based on displacement information that indicates a displacement of a linear motion mechanism included in a machine tool; a second calculation unit that calculates a second speed signal based on acceleration information that indicates an acceleration of the linear motion mechanism; a third calculation unit that calculates a third speed signal based on the first speed signal and the second speed signal; and a state estimation unit that estimates a state of the linear motion mechanism based on motor information related to a motor that drives the linear motion mechanism and the third speed signal.

[0124] This allows the speed of the linear motion mechanism to be calculated with high accuracy. Therefore, the state of the linear motion mechanism can be estimated using the speed of the linear motion mechanism that has been calculated with high accuracy, and therefore the state of the linear motion mechanism can be estimated with high accuracy.

[0125] Technique 2 is the arithmetic device according to Technique 1, in which the first calculation unit includes a first filter unit that filters noise in the displacement information and a differentiator that calculates the first velocity signal by differentiating the displacement information filtered by the first filter unit, and the second calculation unit includes a second filter unit that filters noise in the acceleration information and has filter characteristics different from those of the first filter unit, and an integrator that calculates the second velocity signal by integrating the acceleration information filtered by the second filter unit.

[0126] This allows the speed of the linear motion mechanism to be calculated with high accuracy.

[0127] Technology 3 is the arithmetic device according to Technology 1, including a first filter unit that filters noise in the displacement information, and a second filter unit that filters noise in the acceleration information and has filter characteristics different from those of the first filter unit, wherein the first calculation unit calculates the first velocity signal based on the displacement information filtered by the first filter unit, and the second calculation unit calculates the second velocity signal based on the acceleration information filtered by the second filter unit.

[0128] This allows the speed of the linear motion mechanism to be calculated with high accuracy.

[0129] A fourth technique is the arithmetic device according to the second or third technique, in which the first filter unit is a low-pass filter and the second filter unit is a high-pass filter.

[0130] This allows the speed of the linear motion mechanism to be calculated with high accuracy.

[0131] Technique 5 is the arithmetic device according to Technique 2 or 3, wherein the first filter unit is a band-stop filter, and the second filter unit is a band-pass filter.

[0132] This allows the speed of the linear motion mechanism to be calculated with high accuracy.

[0133] Technique 6 is the arithmetic device according to any one of techniques 1 to 5, wherein the motor information includes at least one of current information indicating an input current to the motor and motor rotation information indicating a rotation angle of the motor.

[0134] This allows the state estimation unit to accurately estimate the state of the linear motion mechanism based on the third speed signal and at least one of the current information and the motor rotation information included in the motor information.

[0135] Technology 7 is the arithmetic device according to any one of Technology 1 to Technology 6, wherein the state estimation unit estimates, as the state of the linear motion mechanism, a cutting resistance that a workpiece exerts on the linear motion mechanism when a tool provided in the machine tool cuts the workpiece.

[0136] This allows the cutting resistance acting on the linear motion mechanism to be estimated with high accuracy.

[0137] Technology 8 is a machine tool including a calculation device according to any one of Technology 1 to Technology 7, a spindle that supports a tool for machining a workpiece, a stage on which the workpiece is placed, a displacement sensor that detects the displacement of the linear motion mechanism, an acceleration sensor that detects the acceleration of the linear motion mechanism, and a display unit that displays the estimation result of the state estimation unit, wherein the linear motion mechanism is at least one of the spindle and the stage.

[0138] This allows the display unit to display the state of at least one of the spindle and the stage, which is the state of the linear motion mechanism estimated with high accuracy by the computing device, making it easier for the operator to check the state of at least one of the spindle and the stage.

[0139] Technique 9 is a calculation method that calculates a first speed signal based on displacement information that indicates the displacement of a linear motion mechanism included in a machine tool, calculates a second speed signal based on acceleration information that indicates the acceleration of the linear motion mechanism, calculates a third speed signal based on the first speed signal and the second speed signal, and estimates a state of the linear motion mechanism based on motor information related to a motor that drives the linear motion mechanism and the third speed signal.

[0140] This provides the same effect as the arithmetic device described in the first technique.

[0141] (Other Embodiments) Although the embodiments have been described above, the present disclosure is not limited to the above-described embodiments.

[0142] For example, in the above embodiment, a process executed by a specific processing unit may be executed by another processing unit. Also, the order of multiple processes may be changed, or multiple processes may be executed in parallel.

[0143] Furthermore, for example, in the above-described embodiments, each component of the processing unit may be realized by executing a software program suitable for that component. Each component may be realized by a program execution unit such as a CPU or processor reading and executing a software program recorded on a recording medium such as a hard disk or semiconductor memory.

[0144] Furthermore, each component may be realized by hardware. Each component may be a circuit (or integrated circuit). These circuits may form a single circuit as a whole, or each may be a separate circuit. Furthermore, each of these circuits may be a general-purpose circuit or a dedicated circuit.

[0145] Furthermore, the method of communication between the devices in the above-described embodiment is not particularly limited, and a relay device (such as a broadband router) may be used in the communication between the devices.

[0146] Furthermore, the general or specific aspects of the present disclosure may be realized as a system, an apparatus, a method, an integrated circuit, a computer program, or a non-transitory recording medium such as a computer-readable CD-ROM. Also, the present disclosure may be realized as any combination of a system, an apparatus, a method, an integrated circuit, a computer program, and a recording medium. For example, the present disclosure may be realized as a calculation method, a program for causing a computer to execute the calculation method, or a non-transitory recording medium on which such a program is recorded and which is readable by a computer.

[0147] In addition, this disclosure also includes forms obtained by applying various modifications to the embodiments that a person skilled in the art would think of, or forms realized by arbitrarily combining the components and functions of the embodiments within the scope that does not deviate from the intent of this disclosure.

[0148] The present disclosure is applicable to machine tools that cut and machine workpieces.

[0149] 10, 10A Machine tool 11, 11A Machine tool control unit 20 Workpiece 30 Tool 40 Spindle 50 Stage 60, 61, 62, 63 Motor 70, 71, 72 Sensor 80, 81, 82, 82A Servo amplifier 90 Inverter 100, 101, 102 Calculation device 200, 201, 202 Calculation unit 210, 210A, 210B First calculation unit 211 Differentiator 212 First filter unit 220, 220A, 220B Second calculation unit 221 Integrator 222 Second filter unit 230 Third calculation unit 231 Adder 300 State estimation unit 400 Linear motion mechanism 500 Command unit 600 Display unit

Claims

1. A calculation device comprising: a first calculation unit that calculates a first speed signal based on displacement information indicating a displacement of a linear motion mechanism provided in a machine tool; a second calculation unit that calculates a second speed signal based on acceleration information indicating an acceleration of the linear motion mechanism; a third calculation unit that calculates a third speed signal based on the first speed signal and the second speed signal; and a state estimation unit that estimates a state of the linear motion mechanism based on motor information related to a motor that drives the linear motion mechanism and the third speed signal.

2. The arithmetic device according to claim 1, wherein the first calculation unit comprises: a differentiator which calculates the first velocity signal by differentiating the displacement information; and a first filter unit which filters noise of the first velocity signal calculated by the differentiator; the second calculation unit comprises: an integrator which calculates the second velocity signal by integrating the acceleration information; and a second filter unit which filters noise of the second velocity signal and has filter characteristics different from those of the first filter unit; and the third calculation unit calculates the third velocity signal based on the first velocity signal filtered by the first filter unit and the second velocity signal filtered by the second filter unit.

3. The arithmetic device according to claim 1, wherein the first calculation unit comprises: a first filter unit that filters noise in the displacement information; and a differentiator that calculates the first velocity signal by differentiating the displacement information filtered by the first filter unit; and the second calculation unit comprises: a second filter unit that filters noise in the acceleration information and has filter characteristics different from those of the first filter unit; and an integrator that calculates the second velocity signal by integrating the acceleration information filtered by the second filter unit.

4. The arithmetic device according to claim 2, wherein the first filter section is a low-pass filter, and the second filter section is a high-pass filter.

5. The arithmetic device according to claim 2, wherein the first filter section is a band-stop filter, and the second filter section is a band-pass filter.

6. The computing device according to claim 1, wherein the motor information includes at least one of current information indicating an input current to the motor and motor rotation information indicating a rotation angle of the motor.

7. The computing device according to claim 1, wherein the state estimation unit estimates, as the state of the linear motion mechanism, a cutting resistance that a workpiece exerts on the linear motion mechanism when a tool provided in the machine tool cuts the workpiece.

8. A machine tool comprising: a calculation device according to any one of claims 1 to 7; a spindle supporting a tool for machining a workpiece; a stage on which the workpiece is placed; a displacement sensor detecting the displacement of the linear motion mechanism; an acceleration sensor detecting the acceleration of the linear motion mechanism; and a display displaying the estimation result of the state estimation unit, wherein the linear motion mechanism is at least one of the spindle and the stage.

9. A calculation method comprising: calculating a first speed signal based on displacement information indicating the displacement of a linear motion mechanism provided in a machine tool; calculating a second speed signal based on acceleration information indicating the acceleration of the linear motion mechanism; calculating a third speed signal based on the first speed signal and the second speed signal; and estimating a state of the linear motion mechanism based on motor information related to a motor that drives the linear motion mechanism and the third speed signal.

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