Control device, machine tool system, and machining method

Abstract

A control device (3) comprises: a first deformation estimation unit (21) that calculates a first deformation, which is the deformation of at least one drive subsystem out of a feed drive subsystem and a spindle drive subsystem (11) due to heat generated in the drive subsystem, by inputting at least one of operation information representing a state quantity of the drive subsystem and temperature information indicating the temperature of the drive subsystem into a first deformation estimation model; a thermal displacement calculation unit (23) that uses kinematic configuration information about a machine tool (2) to convert the first deformation to a thermal displacement, which is the relative displacement between a tool and a workpiece; and a correction command generation unit (25) that generates a correction command to correct the position commanded to the feed drive subsystem on the basis of the thermal displacement.

Description

Control device, machine tool system, and machining method

[0001] The present disclosure relates to a control device for controlling a machine tool, a machine tool system, and a machining method.

[0002] Thermal deformation of the machine tool structure or components causes a change in the position or attitude of the tool relative to the workpiece, which is referred to as thermal displacement of the machine tool. Thermal displacement of the machine tool includes thermal displacement caused by the operation of the machine tool and thermal displacement caused by factors external to the machine tool. Because thermal displacement of the machine tool can be a factor in machining errors, various techniques have been proposed to correct thermal displacement of the machine tool.

[0003] Patent Document 1 discloses a machine tool that calculates an environmental temperature system thermal displacement amount, which is a thermal displacement amount caused by a heat source external to the machine tool, and a drive system thermal displacement amount, which is a thermal displacement amount caused by a heat source provided in the machine tool, and performs control to correct thermal displacement based on a total correction amount obtained by adding together a correction amount for compensating for the environmental temperature system thermal displacement amount and a correction amount for compensating for the drive system thermal displacement amount. The machine tool disclosed in Patent Document 1 obtains a correction amount for compensating for the environmental temperature system thermal displacement amount by multiplying the environmental temperature system thermal displacement amount by a correction factor. The machine tool disclosed in Patent Document 1 is capable of adjusting the correction factor by which the environmental temperature system thermal displacement amount is multiplied.

[0004] International Publication No. 2016 / 067874

[0005] When the drive system of a machine tool deforms due to heat, the effect of the deformation of the drive system on the thermal displacement of the machine tool varies depending on the mechanisms provided in the machine tool or the position or angle of the drive system. According to conventional technology such as that described in Patent Document 1, for deformation caused by heat generation in the drive system, only the amount of thermal displacement in the driving direction of the drive system is calculated. Therefore, with this conventional technology, there was a problem in that a constant amount of thermal displacement was calculated regardless of the relative position or orientation of the tool and workpiece.

[0006] The present disclosure has been made in view of the above, and has an object to provide a control device that can correct thermal displacement with high precision.

[0007] In order to solve the above-mentioned problems and achieve the object, a control device according to the present disclosure is a control device for controlling a machine tool including one or more feed drive systems that move a tool and a workpiece relative to each other, and a spindle drive system that rotates the tool or the workpiece. The control device according to the present disclosure includes: a first deformation amount estimating unit that calculates a first deformation amount, which is the deformation amount of the drive system that is caused by heat generation in at least one of the feed drive system and the spindle drive system, by inputting at least one of operating information that represents a state quantity of the drive system and temperature information that indicates the temperature of the drive system into a first deformation amount estimation model; a thermal displacement amount calculating unit that converts the first deformation amount into a thermal displacement amount, which is the relative displacement amount between the tool and the workpiece, using kinematic configuration information of the machine tool; and a correction command generating unit that generates a correction command to correct a position commanded to the feed drive system based on the thermal displacement amount.

[0008] The control device according to the present disclosure has the effect of being able to correct thermal displacement with high precision.

[0009] FIG. 1 is a block diagram showing a configuration example of a machine tool system according to a first embodiment; FIG. 2 is a diagram showing a schematic appearance of a machine tool according to the first embodiment; FIG. 3 is a diagram showing a configuration example of a first deformation amount estimation model according to the first embodiment; FIG. 4 is a diagram for explaining kinematic configuration information of a machine tool according to the first embodiment; FIG. 5 is a diagram showing a schematic appearance of a machine tool according to a first modification of the first embodiment; FIG. 6 is a diagram for explaining kinematic configuration information of a machine tool according to a second modification of the first embodiment;

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A control device, a machine tool system, and a machining method according to embodiments will be described in detail below with reference to the accompanying drawings.

[0011] Embodiment 1. Prior to a specific description of embodiment 1, an explanation will be given of the terms used in the description of embodiment 1. In embodiment 1, the machine tool system is a system including a machine tool and a control device that controls the machine tool.

[0012] The drive systems of machine tools are classified into spindle drive systems and feed drive systems. Feed drive systems are classified into linear feed drive systems and rotary feed drive systems. Linear feed drive systems impart linear motion to a driven body and position the driven body in a linear direction. Rotary feed drive systems impart rotational motion to a driven body and position the driven body in the rotational direction.

[0013] Components of a machine tool other than the drive system are referred to as structural members. Examples of structural members include a bed, a column, a saddle, and a table. Components of the drive system provided in a machine tool include a motor, an encoder, a ball screw, and a shaft. The driven body is another drive system driven by the drive system, or the structural member. In the following description, the components of the drive system are also referred to as machine elements.

[0014] In the first embodiment, one or more temperature sensors are installed in the machine tool. The temperature sensors detect the temperatures of the structural members. The machine tool may also be installed with a temperature sensor that detects the temperature of the drive system.

[0015] Each drive system in a machine tool is connected to a control device. The control device generates commands for controlling each drive system in accordance with a machining program, which is an NC (Numerical Control) program, and sends the commands to each drive system. Each drive system drives a driven object in accordance with the commands.

[0016] In the first embodiment, thermal deformation refers to deformation of the shape of a structural member or the shape of a drive system due to the influence of heat. The amount of thermal deformation refers to the amount by which a reference point in the shape of a structural member moves due to thermal deformation, or the amount by which a reference point in the shape of a drive system moves due to thermal deformation. In the first embodiment, the amount of thermal deformation of a structural member is expressed as the displacement of a reference point of the structural member in a coordinate system fixed to the structural member. The amount of thermal deformation of a drive system is expressed as the displacement of a reference point of the drive system in a coordinate system fixed to the drive system.

[0017] In the first embodiment, a change in the relative position or attitude of the tool with respect to the workpiece due to thermal deformation of a structural member or thermal deformation of the drive system is referred to as thermal displacement between the tool and the workpiece. The amount of thermal displacement between the tool and the workpiece is referred to as the amount of thermal displacement. The amount of thermal displacement represents the thermal displacement of the tool in a coordinate system fixed to the workpiece.

[0018] Next, a machine tool system according to a first embodiment will be described. Fig. 1 is a block diagram showing an example of the configuration of a machine tool system 1 according to the first embodiment. The machine tool system 1 includes a machine tool 2 and a control device 3 which is a numerical control device. The control device 3 controls the machine tool 2. The machine tool 2 and the control device 3 are connected to each other so that they can communicate with each other.

[0019] 2 is a diagram schematically illustrating the appearance of machine tool 2 according to embodiment 1. Machine tool 2 machines workpiece 36 while moving tool 35 and workpiece 36 relative to each other by driving a plurality of axes that are feed axes.

[0020] The machine tool 2 shown in Figure 2 is a so-called vertical machining center. The machine tool 2 includes a bed 30, which is the base of the machine tool 2, a column 31 disposed on the bed 30, a table 32 to which a workpiece 36 is fixed, a head 33 supported by the column 31, and a spindle 34 attached to the head 33. A tool 35 is attached to the spindle 34. Each of the bed 30, column 31, table 32, and head 33 is a structural member.

[0021] 1, the machine tool 2 includes a plurality of temperature sensors 10, a spindle drive system 11, an X-axis drive system 12, a Y-axis drive system 13, and a Z-axis drive system 14. Each of the plurality of temperature sensors 10 detects the temperature of a structural member or a drive system. Each temperature sensor 10 outputs the temperature detection result to the control device 3.

[0022] The spindle drive system 11 includes a spindle 34. The spindle drive system 11 rotates a tool 35 attached to the spindle 34. The tool 35 is rotated by the driving force of a motor included in the spindle drive system 11. The X-axis drive system 12, the Y-axis drive system 13, and the Z-axis drive system 14 are each a linear feed drive system. The machine tool 2 includes a three-axis linear feed drive system. Note that in FIG. 1, components of the machine tool 2 other than the temperature sensor 10 and each drive system are not shown.

[0023] The X-axis drive system 12 includes a ball screw, a motor that rotates the ball screw, and a mechanism that converts the rotational motion of the ball screw into linear motion in the X-axis direction. The X-axis drive system 12 moves the table 32 in the X-axis direction. The Y-axis drive system 13 includes a ball screw, a motor that rotates the ball screw, and a mechanism that converts the rotational motion of the ball screw into linear motion in the Y-axis direction. The Y-axis drive system 13 moves the table 32 in the Y-axis direction. The Z-axis drive system 14 includes a ball screw, a motor that rotates the ball screw, and a mechanism that converts the rotational motion of the ball screw into linear motion in the Z-axis direction. The Z-axis drive system 14 moves the head 33 in the Z-axis direction.

[0024] As described above, the machine tool 2 includes three feed drive systems that move the tool 35 and the workpiece 36 relative to each other, and a spindle drive system 11 that rotates the tool 35. In Fig. 2, the double-headed arrow marked "X" indicates the drive direction of the X-axis drive system 12. The double-headed arrow marked "Y" indicates the drive direction of the Y-axis drive system 13. The double-headed arrow marked "Z" indicates the drive direction of the Z-axis drive system 14. Details of each drive system are not shown in the figures.

[0025] The control device 3 includes a deformation amount estimation model memory unit 20, a first deformation amount estimation unit 21, a second deformation amount estimation unit 22, a thermal change amount calculation unit 23, a configuration information memory unit 24, a correction command generation unit 25, and a control unit 26.

[0026] The deformation amount estimation model storage unit 20 stores a first deformation amount estimation model and a second deformation amount estimation model. Each of the first deformation amount estimation model and the second deformation amount estimation model is a deformation amount estimation model for estimating the thermal deformation amount from input information. The deformation amount estimation model mathematically describes the process of calculating the thermal deformation amount based on the input information. The control device 3 holds the first deformation amount estimation model and the second deformation amount estimation model in the deformation amount estimation model storage unit 20.

[0027] The first deformation estimation model is a deformation estimation model for estimating the thermal deformation, which is the deformation of a drive system caused by heat generation in at least one of the feed drive system and the spindle drive system. In the following description, the thermal deformation, which is the deformation of the drive system caused by heat generation in the drive system, is referred to as the first deformation.

[0028] The second deformation amount estimation model is a deformation amount estimation model for estimating the thermal deformation amount, which is the deformation amount of a structural member caused by temperature changes in the environment in which the machine tool 2 is installed. In the following description, the thermal deformation amount, which is the deformation amount of a structural member caused by temperature changes in the environment in which the machine tool 2 is installed, will be referred to as the second deformation amount.

[0029] The first deformation amount estimating unit 21 reads out the first deformation amount estimation model from the deformation amount estimation model storage unit 20. The first deformation amount estimating unit 21 calculates the first deformation amount by inputting at least one of driving information representing the state quantity of the drive system and temperature information indicating the temperature of the drive system into the first deformation amount estimation model. The first deformation amount estimating unit 21 outputs the calculation result of the first deformation amount to the thermal change amount calculating unit 23. The temperature information indicating the temperature of the drive system is information input to the control device 3 from the temperature sensor 10 that detects the temperature of the drive system. In the following description, the temperature information indicating the temperature of the drive system will be referred to as temperature information of the drive system. Details of the driving information will be described later.

[0030] The second deformation amount estimating unit 22 reads out the second deformation amount estimation model from the deformation amount estimation model storage unit 20. The second deformation amount estimating unit 22 calculates the second deformation amount by inputting temperature information indicating the temperature of the structural member to the second deformation amount estimation model. The second deformation amount estimating unit 22 outputs the calculation result of the second deformation amount to the thermal displacement amount calculating unit 23. The temperature information indicating the temperature of the structural member is information input to the control device 3 from the temperature sensor 10 that detects the temperature of the structural member.

[0031] The configuration information storage unit 24 stores kinematic configuration information of the machine tool 2. Details of the kinematic configuration information of the machine tool 2 will be described later. In the following description, the kinematic configuration information of the machine tool 2 will also be simply referred to as configuration information. The thermal displacement amount calculation unit 23 reads out the configuration information from the configuration information storage unit 24.

[0032] The thermal change amount calculation unit 23 converts the first deformation amount into a thermal change amount, which is the relative displacement amount between the tool 35 and the workpiece 36, using kinematic configuration information of the machine tool 2. The thermal change amount calculation unit 23 also combines the thermal change amount converted from the first deformation amount with the second deformation amount. In this way, the thermal change amount calculation unit 23 calculates the thermal change amount combined with the second deformation amount. The thermal change amount calculation unit 23 outputs the calculated thermal change amount to the correction command generation unit 25.

[0033] The correction command generator 25 generates a correction command for correcting a command position, which is a position commanded to the feed drive system, based on the thermal change amount calculated by the thermal change amount calculator 23. That is, the correction command generator 25 generates a correction command for correcting the command position based on the thermal change amount combined with the second deformation amount. The correction command generator 25 outputs the generated correction command to the controller 26.

[0034] The control unit 26 generates commands for each drive system of the machine tool 2 in accordance with the machining program. The control unit 26 controls each drive system by sending commands to each drive system. The control unit 26 corrects the command position of each drive system based on the correction command. For example, the control unit 26 performs correction based on the correction command, such as subtracting a length corresponding to the amount of thermal displacement from the coordinates of the command position. The control unit 26 outputs commands with the corrected command position to each drive system.

[0035] The first deformation estimation model represents the relationship between the input and the output when at least one of drivetrain operation information and drivetrain temperature information is used as an input and the first deformation amount, which is the amount of thermal deformation of the drivetrain, is used as an output. Here, the inputs to the first deformation estimation model are the drivetrain operation information and the drivetrain temperature information.

[0036] Here, the operation information input to the first deformation amount estimation model will be described. The operation information is, for example, a value used for servo control of the drive system, and indicates a state quantity such as position, speed, or current. In this case, the operation information is a command value output from the control device 3 to each drive system, or a value such as position, speed, or current indicating the state of each drive system. The operation information may be modal information. The modal information is operation mode information described in the machining program. The operation information may be a value obtained in the process of calculating a command value by the control device 3. Alternatively, the operation information may be a state quantity value obtained by a sensor installed separately from the configuration for servo control of the drive system. Two or more of the above-mentioned types of operation information may be input to the first deformation amount estimation model.

[0037] Next, an example of the first deformation amount estimation model will be described. One example of the first deformation amount estimation model is a model based on a machine learning technique. Below, a case will be described in which the first deformation amount estimation model is a neural network, which is a model based on a machine learning technique. The first deformation amount estimation model, which is a neural network, is the result of learning the relationship between the driving information and temperature information and the first deformation amount through supervised learning. Supervised learning is a technique in which a learning device is provided with a set of input and result, thereby learning the characteristics of learning data and inferring a result from the input. The learning data includes an input and a label representing a result corresponding to the input. The driving information and temperature information correspond to the input. The first deformation amount is supervised data and corresponds to a label.

[0038] Fig. 3 is a diagram showing an example of the configuration of a first deformation amount estimation model in embodiment 1. Fig. 3 shows an example of the configuration of a neural network. The neural network is composed of an input layer consisting of a plurality of neurons, a hidden layer which is an intermediate layer consisting of a plurality of neurons, and an output layer consisting of a plurality of neurons.

[0039] In the example shown in Fig. 3, the output layer consists of three neurons. The output layer outputs the amount of thermal change in the X-axis direction, the amount of thermal change in the Y-axis direction, and the amount of thermal change in the Z-axis direction using the three neurons. The number of neurons in the input layer is determined by the amount of operational information or temperature information selected as input data. The number of neurons in the intermediate layer is arbitrary.

[0040] At least one of drivetrain operating information and drivetrain temperature information is input to the input layer as time-series data. That is, the operating information or temperature information input to the input layer is information from a specific time point back to a predetermined time period. For example, if the information input to the input layer is temperature information and the temperature at time t is represented as T(t), the input layer receives temperature information consisting of a set of "T(t-NΔt), ..., T(t-Δt), T(t)." T(t-NΔt), ..., T(t-Δt), T(t) are input to (N+1) neurons, respectively. Here, Δt represents the sampling period. N represents a constant for referencing information going back a predetermined period.

[0041] Each of the multiple values ​​input to the input layer is multiplied by a weight for each neuron in the input layer and then input to the intermediate layer. Each of the multiple values ​​input to the intermediate layer is multiplied by a weight for each neuron in the intermediate layer and then input to the output layer. Each of the multiple values ​​input to the output layer is multiplied by a weight for each neuron in the output layer. The output layer outputs the first deformation amounts, which are the thermal displacement amounts in the X-axis direction, the Y-axis direction, and the Z-axis direction at time t. The neural network is generated by adjusting the weights so that the output for each input approaches the label.

[0042] The first deformation amount estimation model is not limited to the neural network described above. The first deformation amount estimation model may be, for example, a recurrent neural network including a recursive structure. A recurrent neural network includes time-series processing within the network, and thus can represent a time-series correspondence between input information and output information.

[0043] The first deformation amount estimation model may be a model based on a technique other than machine learning. The first deformation amount estimation model may be a regression model that inputs time-series driving information and calculates the deformation amount at each time. One example of the first deformation amount estimation model that is a regression model is expressed by the following equation (1).

[0044]

[0045] In formula (1), d drv,x is the amount of thermal deformation of the drive system in the X-axis direction, t is time, a, b, and c are coefficients, Ω is the rotation speed of the main shaft 34, N1, N2, and N3 are orders, and N T represents the number of temperature sensors 10, T represents the temperature information of the driving system, and Δt represents the sampling period.

[0046] Equation (1) indicates that the amount of thermal deformation one sampling period after a certain time depends on the amount of thermal deformation before the current time, the rotational speed of the spindle 34 before the current time, and the temperature before the current time. The regression model represented by equation (1) includes a time-delay term of the input information. In equation (1), "-kΔt" represents a time delay. Each term on the right side of equation (1) is a time-delay term including "-kΔt." Equation (1) is also a calculation formula that uses a time-series signal as input. When the first deformation amount estimation model is the regression model represented by equation (1), the rotational speed and temperature information of the drivetrain, which are operating information, are input to the first deformation amount estimation model, and the thermal deformation amount is output from the first deformation amount estimation model.

[0047] Each term on the right side of equation (1) represents a linear sum of state quantities. A term that is the square or higher of the state quantity may be added to each term on the right side of equation (1). Equation (1) represents a formula for calculating the amount of thermal deformation of the drive system in the X-axis direction. The amount of thermal deformation of the drive system in the Y-axis direction and the amount of thermal deformation of the drive system in the Z-axis direction can also be calculated using the same calculation as for the amount of thermal deformation of the drive system in the X-axis direction.

[0048] As an example other than the above models, when calculating the thermal deformation amount only in the axial direction of the drive system, the first deformation amount estimation model may be a model that calculates the sum of the deformation amounts of multiple mechanical elements that make up the drive system. In this case, the first deformation amount estimation model inputs temperature information for each mechanical element, such as the shaft, bearing, and ball screw, and calculates the axial thermal deformation amount by calculating the sum of the values ​​for each mechanical element. In this case, the first deformation amount estimation model for the Z-axis drive system 14 is expressed by the following equation (2):

[0049]

[0050] In formula (2), d z where t is the amount of thermal deformation in the Z-axis direction, t is time, i is a number representing a mechanical element of the drive system, α is the thermal expansion coefficient of the mechanical element, L is the axial length of the drive system, and ΔT is the temperature change of the mechanical element. Equation (2) is a calculation formula that uses a time-series signal as input. Equation (2) represents the calculation formula for the amount of thermal deformation of the Z-axis drive system 14 in the Z-axis direction. The amount of thermal deformation of the X-axis drive system 12 in the X-axis direction and the amount of thermal deformation of the Y-axis drive system 13 in the Y-axis direction can also be calculated using the same calculation as for the amount of thermal deformation of the Z-axis drive system 14 in the Z-axis direction.

[0051] Although several specific examples of the first deformation amount estimation model have been described above, the first deformation amount estimation model is not limited to these. Furthermore, different first deformation amount estimation models may be applied to each drivetrain depending on the thermal characteristics or specifications of each drivetrain. The first deformation amount estimation model may also be input with either drivetrain operating information or drivetrain temperature information.

[0052] The second deformation amount estimation model represents the relationship between input and output when temperature information of the structural member is input and the second deformation amount, which is the thermal deformation amount of the structural member, is output. As with the first deformation amount estimation model, a neural network can be applied to the second deformation amount estimation model. Alternatively, the second deformation amount estimation model may be a regression model that inputs time-series temperature information and calculates the deformation amount at each time. One example of the second deformation amount estimation model, which is a regression model, is expressed by the following equation (3):

[0053]

[0054] In formula (3), d str,x is the amount of thermal deformation of the structural member in the X-axis direction, t is time, a and c are coefficients, N Trepresents the number of temperature sensors 10, T represents temperature information of the structural member, and Δt represents the sampling period. Each term on the right side of equation (3) is a time-lag term including "-kΔt." Equation (3) indicates that the amount of thermal deformation one sampling period after a certain time depends on the amount of thermal deformation and the temperature before the current time. The regression model represented by equation (3) includes a time-lag term for the input information. Equation (3) is also a calculation formula that uses a time-series signal as input. When the second deformation estimation model is the regression model represented by equation (3), temperature information of the structural member is input to the second deformation estimation model, and the thermal deformation amount is output from the second deformation estimation model.

[0055] The second deformation estimation model may be a model using the finite element method. In a model using the finite element method, a structural member is divided into a plurality of infinitesimal elements, and a regression model is set in advance for each of the infinitesimal elements. In this case, temperature information detected by the temperature sensor 10 is input to the second deformation estimation model, and the sum of the thermal deformation amounts of the infinitesimal elements included in the structural member is output from the second deformation estimation model as the final thermal deformation amount.

[0056] As described above, in the first embodiment, at least one of the first deformation amount estimation model and the second deformation amount estimation model may be a neural network model. Also, in the first embodiment, at least one of the first deformation amount estimation model and the second deformation amount estimation model may be a calculation formula that uses a time-series signal as input, or a regression model that includes a time lag term for the input information.

[0057] Next, a detailed description will be given of the processing in the thermal change amount calculation unit 23. The thermal change amount calculation unit 23 converts the first deformation amount into a thermal change amount, which is the relative displacement amount between the tool 35 and the workpiece 36, using kinematic configuration information of the machine tool 2.

[0058] FIG. 4 is a diagram for explaining the kinematic configuration information of the machine tool 2 in the first embodiment. In the first embodiment, the kinematic configuration information of the machine tool 2 is information that kinematically expresses the configuration in which each drive system is connected to the structure of the machine tool 2. In FIG. 4, "Machine tool bed" represents the bed 30. "X axis" represents the X-axis drive system 12. "Y axis" represents the Y-axis drive system 13. "Z axis" represents the Z-axis drive system 14. "Spindle" represents the spindle drive system 11. "Tool" represents the tool 35 attached to the spindle 34. "Workpiece" represents the workpiece 36 fixed to the table 32. Note that the table 32 is omitted from FIG. 4.

[0059] 4 shows a schematic diagram of the connection between the bed 30, which is a structural member, and the drive systems, which are the spindle drive system 11, the X-axis drive system 12, the Y-axis drive system 13, and the Z-axis drive system 14. Fig. 4 can also be said to represent the kinematic connection relationship between a tool 35 and a workpiece 36. Fig. 4 shows that the spindle drive system 11 is positioned by the Z-axis drive system 14, the workpiece 36 is positioned by the X-axis drive system 12, and the X-axis drive system 12 is positioned by the Y-axis drive system 13.

[0060] For components connected to each other, the transformation from a position in a coordinate system fixed to one component to a position in a coordinate system fixed to the other component can be expressed by a homogeneous transformation matrix. In the configuration shown in Figure 4, the tip position of the tool 35 in the workpiece coordinate system is expressed by the following equation (4).

[0061]

[0062] Equation (4) represents coordinate transformation from the tool coordinate system to the workpiece coordinate system. The tool coordinate system is a coordinate system fixed to the tool 35. The workpiece coordinate system is a coordinate system fixed to the workpiece 36. The order of coordinate transformation in equation (4) corresponds to the kinematic configuration information of the machine tool 2 shown in FIG. 4. The thermal displacement amount calculation unit 23 converts the first deformation amount into the thermal displacement amount between the tool 35 and the workpiece 36 by coordinate transformation using equation (4).

[0063] In formula (4), the symbol "P" is a bold "P" with a subscript "T" at the top left. T "P" represents the tip position of the tool 35 in the tool coordinate system. " W P" represents the tip position of the tool 35 in the workpiece coordinate system.

[0064] For the sake of convenience, the subscript to the left of the bold "T" in formula (4) is represented as "m", and the subscript to the left of the bold "T" in formula (4) is represented as "n". Each of "m" and "n" represents a component of the machine tool 2. The symbol "m" and "n" is a symbol formed by adding "m" and "n" to a bold "T". m n "T" is a Denavit-Hartenberg matrix (DH matrix) that represents a coordinate transformation from one component represented by "m" to a coordinate system fixed to another component represented by "n". However, when a subscript "-1" is added to the upper right of the bold "T", the symbol represents a coordinate transformation from one component represented by "n" to a coordinate system fixed to another component represented by "m". In formula (4), "m" or "n", "M", "S", "T", "W", "X", "Y", and "Z" represent the bed 30, the spindle drive system 11, the tool 35, the workpiece 36, the X-axis drive system 12, the Y-axis drive system 13, and the Z-axis drive system 14, respectively.

[0065] In the following explanation, the first deformation amount generated in each drive system is considered to be expressed in the work coordinate system. For simplicity of explanation, it is assumed that the origins of the coordinate systems are the same. W X T" and " T S Each of "T" is an identity matrix. W X "T" is a DH matrix that represents the coordinate transformation from the workpiece 36 to the coordinate system fixed to the X-axis drive system 12. T S "T" is a DH matrix that represents the coordinate transformation from the tool 35 to the coordinate system fixed to the spindle drive system 11. X YT," Y M T," Z M T" and " S Z T" are expressed by the following formulas (5), (6), (7), and (8), respectively. X Y "T" is a DH matrix representing the coordinate transformation from the X-axis drive system 12 to a coordinate system fixed to the Y-axis drive system 13. Y M "T" is a DH matrix that represents the coordinate transformation from the Y-axis drive system 13 to the coordinate system fixed to the bed 30. Z M "T" is a DH matrix that represents the coordinate transformation from the Z-axis drive system 14 to a coordinate system fixed to the bed 30. S Z T” is a DH matrix representing the coordinate transformation from the spindle drive system 11 to a coordinate system fixed to the Z-axis drive system 14.

[0066]

[0067]

[0068]

[0069]

[0070] In the equations (5) to (8), x, y, and z represent the position of the X-axis drive system 12, the position of the Y-axis drive system 13, and the position of the Z-axis drive system 14, respectively. s , θ x , θ y , θ z represent the temperatures of the spindle drive system 11, the X-axis drive system 12, the Y-axis drive system 13, and the Z-axis drive system 14, respectively. j (i) is a quantity that depends on the position of the i-axis drive system and represents the position error in the j-axis direction. j (i) is a quantity dependent on the position of the i-axis drive system, and represents the angular error in the j-axis direction. Furthermore, the quantity represented by δ corresponds to the amount of thermal deformation in each drive system. Specifically, δ j (i, θ i) is a quantity that depends on the position of the i-axis drive system and the temperature of the i-axis drive system, and represents the position error in the j-axis direction. j (θ s ) is a quantity that depends only on the temperature of the spindle drive system 11 and represents the position error in the j-axis direction. In this description, each of i and j represents any one of the symbols x representing the X-axis drive system 12, y representing the Y-axis drive system 13, and z representing the Z-axis drive system 14. The i-axis drive system represents any one of the X-axis drive system 12, Y-axis drive system 13, and Z-axis drive system 14.

[0071] By using the formulas (5)-(8), the tip position of the tool 35 in the work coordinate system, " W The error amount in the X-axis direction that occurs in "P" is "Δ W P x " can be calculated by the following formula (9): " W The error amount in the Y-axis direction that occurs in "P" is "Δ W P y " can be calculated by the following formula (10): " W The error amount in the Z-axis direction that occurs in "P" is "Δ W P z " can be calculated by the following formula (11). W P x ", "Δ W P y ", and "Δ W P z Each of the expressions "1" and "2" corresponds to the amount of thermal displacement between the tool 35 and the workpiece 36 in the workpiece coordinate system.

[0072]

[0073]

[0074]

[0075] In formulas (9) to (11), S x (y), S x (z), S y(z) represents squareness error. Using equations (9)-(11), the thermal displacement amount calculation unit 23 can calculate the amount of thermal displacement between the tool 35 and the workpiece 36 in the workpiece coordinate system as an amount that depends on position and temperature. In other words, because the coordinate conversion from the first deformation amount caused by heat generation in the drive system to the amount of thermal displacement is performed based on kinematic configuration information, the thermal displacement amount calculation unit 23 can accurately calculate the amount of thermal displacement caused by heat generation in the drive system.

[0076] In the machine tool 2, the spindle drive system 11 is positioned by the Z-axis drive system 14, which is one feed drive system. The first deformation amount in the machine tool 2 is the deformation amount occurring in the spindle drive system 11 due mainly to heat generation in the spindle drive system 11. The thermal displacement amount calculation unit 23 converts the first deformation amount into a thermal displacement amount by coordinate transformation using the configuration information shown in equation (4) in accordance with the position of the spindle drive system 11 and the geometric error of the Z-axis drive system 14, which is the feed drive system that positions the spindle drive system 11. The control device 3 performs coordinate transformation in accordance with the position of the spindle drive system 11 while taking into account the geometric error of the feed drive system, thereby enabling accurate conversion of the deformation amount occurring in the spindle drive system 11 into the thermal displacement amount between the tool 35 and the workpiece 36.

[0077] Furthermore, in the machine tool 2, the X-axis drive system 12 is positioned by the Y-axis drive system 13. The three feed drive systems provided in the machine tool 2 include the X-axis drive system 12, which is a first feed drive system, and the Y-axis drive system 13, which is a second feed drive system that positions the first feed drive system. The first deformation amount in the machine tool 2 includes not only the deformation amount generated in the spindle drive system 11, but also the deformation amount generated in the first feed drive system due to heat generation therein. That is, the first deformation amount includes the deformation amount generated in the X-axis drive system 12 due to heat generation therein. The thermal displacement amount calculation unit 23 converts the first deformation amount into a thermal displacement amount by coordinate transformation using the configuration information shown in equation (4) in accordance with the position of the X-axis drive system 12 and the geometric error of the Y-axis drive system 13, which is the second feed drive system. The control device 3 performs coordinate transformation according to the position of the first feed drive system while taking into account the geometric error of the second feed drive system, thereby accurately converting the amount of deformation occurring in the first feed drive system into the amount of thermal displacement between the tool 35 and the workpiece 36.

[0078] In the first embodiment, the thermal displacement amount calculation unit 23 converts the amount of thermal displacement of the drive system caused by heat generation in the drive system into the amount of thermal displacement between the tool 35 and the workpiece 36. This allows the control device 3 to highly accurately correct the thermal displacement caused by heat generation in the drive system. The machine tool system 1 can reduce machining errors caused by heat generation in the drive system.

[0079] In the above description, the machine tool system 1 is assumed to include the machine tool 2 having a three-axis linear feed drive system, and its kinematic configuration is assumed to be as shown in Fig. 4. The machine tool provided in the machine tool system 1 is not limited to the above-described machine tool 2. Next, modified examples of the machine tool provided in the machine tool system 1 will be described.

[0080] 5 is a diagram schematically showing the appearance of a machine tool 2A according to a first modification of the first embodiment. The machine tool 2A is a lathe having a two-axis linear feed drive system. The machine tool 2A includes an X-axis drive system 12 and a Z-axis drive system 14 that move a tool 35 and a workpiece 36 relative to each other, and a spindle drive system 11 that rotates the workpiece 36. The workpiece 36 is attached to the spindle 34. The machine tool 2A includes a bed 30, which is a structural member.

[0081] The machine tool 2A moves a tool 35 in the X-axis direction and the Z-axis direction by the X-axis drive system 12 and the Z-axis drive system 14. In Fig. 5, the double-headed arrow marked "X" indicates the drive direction of the X-axis drive system 12. The double-headed arrow marked "Z" indicates the drive direction of the Z-axis drive system 14. The X-axis drive system 12 and the Z-axis drive system 14 of the machine tool 2A are not shown. Only the spindle 34 of the spindle drive system 11 is shown in Fig. 5.

[0082] Fig. 6 is a diagram for explaining the kinematic configuration information of machine tool 2A according to Modification 1 of Embodiment 1. In Fig. 6, "Machine tool bed" represents bed 30. "X axis" represents X-axis drive system 12. "Z axis" represents Z-axis drive system 14. "Spindle" represents spindle drive system 11. "Tool" represents tool 35 attached to X-axis drive system 12. "Workpiece" represents workpiece 36 attached to spindle 34.

[0083] 6 shows a schematic diagram of the connection between the bed 30, which is a structural member, and the drive systems, which are the spindle drive system 11, the X-axis drive system 12, and the Z-axis drive system 14. Fig. 6 can also be said to represent the kinematic connection relationship between the tool 35 and the workpiece 36. Fig. 6 shows that the position of the spindle drive system 11 relative to the bed 30 is fixed, that the tool 35 is positioned by the X-axis drive system 12, and that the X-axis drive system 12 is positioned by the Z-axis drive system 14.

[0084] In the machine tool 2A, the X-axis drive system 12 is positioned by the Z-axis drive system 14. The two feed drive systems provided in the machine tool 2A include the X-axis drive system 12, which is a first feed drive system, and the Z-axis drive system 14, which is a second feed drive system that positions the first feed drive system.

[0085] Even when machine tool 2A is provided in machine tool system 1, thermal displacement amount calculation unit 23 converts the amount of thermal deformation of the drive system caused by heat generation in the drive system into the amount of thermal displacement between tool 35 and workpiece 36 in the same manner as in the case of machine tool 2. Thermal displacement amount calculation unit 23 converts the first amount of deformation into the amount of thermal displacement in accordance with the position of X-axis drive system 12 and the geometric error of Z-axis drive system 14, which is the second feed drive system, by coordinate transformation in the same manner as in the case of machine tool 2. Even when machine tool 2A is provided in machine tool system 1, control device 3 can correct thermal displacement caused by heat generation in the drive system with high precision.

[0086] 7 is a diagram schematically illustrating the appearance of a machine tool 2B according to a second modification of the first embodiment. The machine tool 2B has a three-axis linear feed drive system and a two-axis rotary feed drive system. The machine tool 2B is equipped with an X-axis drive system 12, a Y-axis drive system 13, a Z-axis drive system 14, an A-axis drive system, and a C-axis drive system that move a tool 35 and a workpiece 36 relative to one another, and a spindle drive system 11 that rotates the tool 35. The tool 35 is attached to a spindle 34. The workpiece 36 is fixed to a table 32. Each of the bed 30, the table 32, and the head 33 is a structural member.

[0087] The machine tool 2B moves the tool 35 in the X-axis, Y-axis, and Z-axis directions using the X-axis drive system 12, Y-axis drive system 13, and Z-axis drive system 14. The machine tool 2B rotates the table 32 in the A-axis direction using the A-axis drive system. The A-axis direction is the direction of rotation around the A-axis. The A-axis is an axis parallel to the X-axis. The machine tool 2B rotates the table 32 in the C-axis direction using the C-axis drive system. The C-axis direction is the direction of rotation around the C-axis. The C-axis is an axis parallel to the Z-axis. In FIG. 7 , the double-headed arrow marked "X" indicates the drive direction of the X-axis drive system 12. The double-headed arrow marked "Y" indicates the drive direction of the Y-axis drive system 13. The double-headed arrow marked "Z" indicates the drive direction of the Z-axis drive system 14. The double-headed arrow marked "A" indicates the drive direction of the A-axis drive system. The double-headed arrow marked "C" indicates the drive direction of the C-axis drive system. The X-axis drive system 12, the Y-axis drive system 13, the Z-axis drive system 14, the A-axis drive system, and the C-axis drive system of the machine tool 2B are not shown in the figure. In Fig. 7, only the main spindle 34 of the main spindle drive system 11 is shown.

[0088] Fig. 8 is a diagram for explaining the kinematic configuration information of a machine tool 2B according to the second modification of the first embodiment. In Fig. 8, "Machine tool bed" represents the bed 30. "X axis" represents the X-axis drive system 12. "Y axis" represents the Y-axis drive system 13. "Z axis" represents the Z-axis drive system 14. "A axis" represents the A-axis drive system. "C axis" represents the C-axis drive system. "Spindle" represents the spindle drive system 11. "Tool" represents the tool 35 attached to the spindle 34. "Workpiece" represents the workpiece 36 fixed to the table 32.

[0089] Figure 8 schematically shows the connection between the bed 30, which is a structural member, and the drive systems, which are the spindle drive system 11, the X-axis drive system 12, the Y-axis drive system 13, the Z-axis drive system 14, the A-axis drive system, and the C-axis drive system. Figure 8 can also be said to represent the kinematic connection relationship between a tool 35 and a workpiece 36. Figure 8 shows that the spindle drive system 11 is positioned by the Z-axis drive system 14, that the Z-axis drive system 14 is positioned by the Y-axis drive system 13, and that the Y-axis drive system 13 is positioned by the X-axis drive system 12. Figure 8 also shows that the attitude of the workpiece 36 is determined by the C-axis drive system, and that the attitude of the C-axis drive system is determined by the A-axis drive system.

[0090] When machine tool system 1 is equipped with machine tool 2B, thermal displacement calculation unit 23 converts the first deformation amount into a thermal displacement amount by adding transformations for the A-axis drive system and the C-axis drive system to the coordinate transformation for machine tool 2. Thermal displacement calculation unit 23 converts the first deformation amount into a thermal displacement amount according to the angle imparted by the A-axis drive system, which is a rotary feed drive system, and the angle imparted by the C-axis drive system, which is a rotary feed drive system. In this way, thermal displacement calculation unit 23 converts the thermal deformation amount of the drive system into the thermal displacement amount between tool 35 and workpiece 36 according to the angle imparted by the rotary feed drive system. Even when machine tool 2B is equipped in machine tool system 1, control device 3 can accurately correct thermal displacement caused by heat generation in the drive system.

[0091] The machine tools provided in machine tool system 1 are not limited to machine tools 2, 2A, and 2B described in embodiment 1. The machine tools provided in machine tool system 1 may be any machine tools that include one or more feed drive systems that move tool 35 and workpiece 36 relative to each other, and a spindle drive system that rotates tool 35 or workpiece 36.

[0092] Next, a description will be given of the operation procedure of the machine tool system 1. Fig. 9 is a flowchart showing an example of the operation procedure of the machine tool system 1 according to the first embodiment. Here, it is assumed that the machine tool system 1 is provided with the machine tool 2 shown in Figs. 1 and 2.

[0093] In step S1, the machine tool 2 machines the workpiece 36. In step S2, the first deformation amount estimating unit 21 calculates the first deformation amount by inputting at least one of operation information and temperature information to a first deformation amount estimation model. The first deformation amount estimating unit 21 inputs at least one of operation information representing a state quantity of the drive train and temperature information indicating the temperature of the drive train to the first deformation amount estimation model.

[0094] In step S3, the second deformation amount estimation unit 22 calculates the second deformation amount by inputting the temperature information into the second deformation amount estimation model. The second deformation amount estimation unit 22 inputs the temperature information indicating the temperature of the structural member into the second deformation amount estimation model.

[0095] In step S4, the thermal change amount calculation unit 23 converts the first deformation amount calculated in step S2 into a thermal change amount, which is a relative displacement amount between the tool 35 and the workpiece 36. The thermal change amount calculation unit 23 converts the first deformation amount into a thermal change amount using kinematic configuration information of the machine tool 2.

[0096] In step S5, the thermal change amount calculation unit 23 combines the thermal change amount obtained in step S4 with the second deformation amount calculated in step S3. In this way, the thermal change amount calculation unit 23 calculates the thermal change amount combined with the second deformation amount.

[0097] In step S6, the correction command generator 25 generates a correction command for correcting the command position based on the calculated thermal displacement amount. The correction command generator 25 outputs the generated correction command to the controller 26. The controller 26 corrects the command position of each drive system based on the correction command. The controller 26 outputs the command with the corrected command position to each drive system.

[0098] In the machine tool system 1 shown in FIG. 1 , one machine tool 2 is connected to the control device 3. In the machine tool system 1, multiple machine tools 2 may be connected to the control device 3. In this case, the control device 3 controls the multiple machine tools 2. The control device 3 can correct thermal displacement in each of the multiple machine tools 2 with high precision. Note that in a production line equipped with multiple machine tools 2 of the same model, all of the machine tools 2 in the production line may be controlled by a single control device 3. By controlling all of the machine tools 2 in the production line with a single control device 3, the machine tool system 1 can correct thermal displacement in each machine tool 2 in the production line with high precision.

[0099] According to the first embodiment, the control device 3 includes a first deformation amount estimating unit 21 that calculates a first deformation amount by inputting at least one of operation information representing a state quantity of the drive system and temperature information indicating the temperature of the drive system into a first deformation amount estimation model, and a thermal displacement amount calculating unit 23 that converts the first deformation amount into a thermal displacement amount using kinematic configuration information of the machine tool 2. The control device 3 can correct thermal displacement caused by heat generation in the drive system with high accuracy. This achieves the effect of allowing the control device 3 to correct thermal displacement with high accuracy. The machine tool system 1 can reduce machining errors caused by heat generation in the drive system.

[0100] The control device 3 also includes a second deformation amount estimator 22 that calculates a second deformation amount by inputting temperature information indicating the temperature of the structural member into a second deformation amount estimation model. A thermal change amount calculator 23 combines the second deformation amount with the thermal change amount converted from the first deformation amount. The control device 3 estimates each of the thermal change caused by heat generation in the drive system and the thermal change caused by temperature changes in the environment based on the deformation amount estimation model to calculate the thermal change amount. This enables the control device 3 to estimate the thermal change amount with high accuracy and correct the thermal change with high accuracy. The machine tool system 1 can correct machining errors caused by heat generation in the drive system and machining errors caused by temperature changes in the environment with high accuracy.

[0101] In the above description, the control device 3 calculates the amount of thermal deformation using a deformation estimation model stored in the deformation estimation model storage unit 20. The control device 3 may also calculate the amount of thermal deformation using a deformation estimation model read out from a device external to the control device 3. Next, an example in which a deformation estimation model read out from a device external to the control device 3 is used will be described.

[0102] Figure 10 is a block diagram showing an example configuration of a machine tool system 1A according to a modification of the first embodiment. The machine tool system 1A includes a machine tool 2, a control device 3A which is a numerical control device, and a storage device 4. The control device 3A controls the machine tool 2. The storage device 4 is a device external to the control device 3A. Note that while Figure 10 shows an example in which the machine tool system 1A is provided with the machine tool 2, machine tools other than the machine tool 2 may also be provided. In the machine tool system 1A shown in Figure 10, one machine tool 2 is connected to the control device 3A, but multiple machine tools 2 may be connected to the control device 3A.

[0103] The control device 3A differs from the control device 3 shown in FIG. 1 in that the deformation amount estimation model storage unit 20 is omitted and a deformation amount estimation model acquisition unit 27 is included. The storage device 4 stores a plurality of deformation amount estimation models. The machine tool 2 and the control device 3A are connected to each other so that they can communicate with each other. The control device 3A and the storage device 4 are connected to each other so that they can communicate with each other. The storage device 4 may be connected to the control device 3A via a network. The network is, for example, a WAN (Wide Area Network) such as the Internet, but may also be a LAN (Local Area Network). The storage device 4 may be configured by a server built in a cloud environment.

[0104] The deformation amount estimation model acquisition unit 27 selects a deformation amount estimation model to be used as the first deformation amount estimation model and a deformation amount estimation model to be used as the second deformation amount estimation model from among a plurality of deformation amount estimation models stored in the storage device 4. The deformation amount estimation model acquisition unit 27 reads these selected deformation amount estimation models from the storage device 4. As a result, the deformation amount estimation model acquisition unit 27 acquires the first deformation amount estimation model and the second deformation amount estimation model. The deformation amount estimation model acquisition unit 27 outputs the acquired first deformation amount estimation model to the first deformation amount estimation unit 21. The deformation amount estimation model acquisition unit 27 outputs the acquired second deformation amount estimation model to the second deformation amount estimation unit 22.

[0105] The control device 3A can switch the deformation amount estimation model used as the first deformation amount estimation model depending on the drive pattern of each drive system in the machine tool 2. The control device 3A can calculate the first deformation amount using the first deformation amount estimation model suited to the drive pattern. This allows the control device 3A to highly accurately correct thermal displacement caused by heat generation in the drive system.

[0106] The control device 3A can switch the deformation amount estimation model used as the second deformation amount estimation model depending on the environment in which the machine tool 2 is installed. The control device 3A can calculate the second deformation amount using the second deformation amount estimation model suitable for the environment. This allows the control device 3A to correct thermal displacement caused by temperature changes in the environment with high accuracy. When multiple machine tools 2 are connected to the control device 3A, each of the multiple machine tools 2 may use, as the second deformation amount estimation model, a deformation amount estimation model suitable for the environment in which the machine tool 2 is installed. This allows the control device 3A to correct thermal displacement in each of the multiple machine tools 2 with high accuracy.

[0107] Next, a hardware configuration for realizing the control device 3 according to the first embodiment will be described. The control device 3 is realized by a processing circuit. The processing circuit may be a circuit in which a processor executes software, or may be a dedicated circuit. The hardware configuration for realizing the control device 3A is assumed to be the same as the hardware configuration for realizing the control device 3A.

[0108] When the processing circuit is realized by software, the processing circuit is, for example, a control circuit 50 shown in FIG. 11 . FIG. 11 is a diagram showing an example of the configuration of the control circuit 50 according to the first embodiment. The control circuit 50 includes an input unit 51, a processor 52, a memory 53, and an output unit 54. The input unit 51 is an interface circuit that receives data input from outside the control circuit 50 and provides the data to the processor 52. The output unit 54 is an interface circuit that sends data from the processor 52 or the memory 53 to outside the control circuit 50.

[0109] When the processing circuit is the control circuit 50 shown in FIG. 11 , the control device 3 is realized by software, firmware, or a combination of software and firmware. The software or firmware is written as a program and stored in memory 53. The processing circuit realizes each function of the control device 3 by having the processor 52 read and execute the program stored in memory 53. In other words, the processing circuit includes memory 53 for storing programs that result in the processing of the control device 3 being executed. It can also be said that these programs cause a computer to execute the procedures and methods of the control device 3.

[0110] The processor 52 is a CPU (Central Processing Unit). The processor 52 may be a central processing unit, processing unit, arithmetic unit, microprocessor, microcomputer, processor, or DSP. The memory 53 may be, for example, a non-volatile or volatile semiconductor memory such as a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an EPROM (Erasable Programmable Read Only Memory), or an EEPROM (Electrically Erasable Programmable Read Only Memory), a magnetic disk, a flexible disk, an optical disk, a compact disk, a minidisk, or a DVD (Digital Versatile Disc).

[0111] The first deformation amount estimating unit 21, the second deformation amount estimating unit 22, the correction command generating unit 25, and the control unit 26, which are processing units of the control device 3, are realized by the processor 52 and the memory 53. The deformation amount estimation model storing unit 20 and the configuration information storing unit 24, which are storing units of the control device 3, are realized by the memory 53.

[0112] 11 shows an example of hardware in which the processing unit of the control device 3 is realized by a general-purpose processor 52 and memory 53, but the processing unit of the control device 3 may also be realized by a dedicated hardware circuit. Fig. 12 is a diagram showing an example of the configuration of a dedicated hardware circuit 55 according to the first embodiment.

[0113] The dedicated hardware circuit 55 includes an input unit 51, an output unit 54, and a processing circuit 56. The processing circuit 56 is a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a combination thereof. Each function of the control device 3 may be realized by the processing circuit 56 individually, or all functions may be realized collectively by the processing circuit 56. The control device 3 may also be realized by combining the control circuit 50 and the hardware circuit 55.

[0114] 10 , the first deformation amount estimating unit 21, the second deformation amount estimating unit 22, the correction command generating unit 25, the control unit 26, and the deformation amount estimation model acquiring unit 27 are realized by a processor 52 and a memory 53. The configuration information storing unit 24, which is a storing unit of the control unit 3A, is realized by the memory 53. The storage device 4 shown in FIG. 10 is realized by a hardware configuration similar to the hardware configuration illustrated in FIG. 11 or a hardware configuration similar to the hardware configuration illustrated in FIG. 12.

[0115] The configurations described in the above embodiments are examples of the contents of the present disclosure. The configurations of the embodiments can be combined with other known technologies. Part of the configurations of the embodiments can be omitted or modified without departing from the gist of the present disclosure.

[0116] 1, 1A Machine tool system, 2, 2A, 2B Machine tool, 3, 3A Control device, 4 Storage device, 10 Temperature sensor, 11 Spindle drive system, 12 X-axis drive system, 13 Y-axis drive system, 14 Z-axis drive system, 20 Deformation amount estimation model storage unit, 21 First deformation amount estimation unit, 22 Second deformation amount estimation unit, 23 Thermal displacement amount calculation unit, 24 Configuration information storage unit, 25 Correction command generation unit, 26 Control unit, 27 Deformation amount estimation model acquisition unit, 30 Bed, 31 Column, 32 Table, 33 Head, 34 Spindle, 35 Tool, 36 Workpiece, 50 Control circuit, 51 Input unit, 52 Processor, 53 Memory, 54 Output unit, 55 Hardware circuit, 56 Processing circuit.

Claims

1. A control device for controlling a machine tool having one or more feed drive systems for moving a tool and a workpiece relative to each other, and a spindle drive system for rotating the tool or the workpiece, comprising: a first deformation amount estimation unit that calculates a first deformation amount, which is the deformation amount of the drive system, which is at least one of the feed drive system and the spindle drive system, by inputting at least one of operating information that represents a state quantity of the drive system and temperature information that indicates the temperature of the drive system, into a first deformation amount estimation model; a thermal displacement amount calculation unit that converts the first deformation amount into a thermal displacement amount, which is the relative displacement amount between the tool and the workpiece, using kinematic configuration information of the machine tool; and a correction command generation unit that generates a correction command to correct the position commanded to the feed drive system based on the thermal displacement amount.

2. The control device described in claim 1, further comprising a second deformation amount estimation unit that calculates a second deformation amount, which is the deformation amount of the structural member caused by a temperature change in the environment in which the machine tool is installed, by inputting temperature information indicating the temperature of a structural member that is a component of the machine tool other than the feed drive system and the spindle drive system into a second deformation amount estimation model, wherein the thermal displacement amount calculation unit combines the second deformation amount with the thermal displacement amount converted from the first deformation amount, and the correction command generation unit generates the correction command for correcting the position to be commanded to the feed drive system based on the thermal displacement amount combined with the second deformation amount.

3. The control device according to claim 1 or 2, characterized in that the spindle drive system is positioned by at least one of the one or more feed drive systems, the first deformation amount is a deformation amount occurring in the spindle drive system due to heat generation from the spindle drive system, and the thermal displacement amount calculation unit converts the first deformation amount into the thermal displacement amount depending on the position of the spindle drive system and a geometric error of the feed drive system that positions the spindle drive system.

4. The control device described in claim 1 or 2, characterized in that the machine tool is equipped with a plurality of feed drive systems including a first feed drive system and a second feed drive system that positions the first feed drive system, the first deformation amount is a deformation amount occurring in the first feed drive system due to heat generation of the first feed drive system, and the thermal displacement amount calculation unit converts the first deformation amount into the thermal displacement amount depending on the position of the first feed drive system and the geometric error of the second feed drive system.

5. The control device described in claim 3 or 4, characterized in that one or more of the feed drive systems includes a rotary feed drive system which rotates the tool and the workpiece relative to each other, and the thermal displacement amount calculation unit converts the first deformation amount into the thermal displacement amount according to the angle provided by the rotary feed drive system.

6. The control device according to claim 2, wherein at least one of the first deformation amount estimation model and the second deformation amount estimation model is a neural network model.

7. The control device according to claim 2, characterized in that at least one of the first deformation amount estimation model and the second deformation amount estimation model is a calculation formula that uses a time series signal as input, or a regression model that includes a time lag term for the input information.

8. A machine tool system comprising: a machine tool having one or more feed drive systems for moving a tool and a workpiece relative to each other, and a spindle drive system for rotating the tool or the workpiece; and a control device for controlling the machine tool, wherein the control device comprises: a first deformation amount estimation unit that calculates a first deformation amount, which is the deformation amount of the drive system caused by heat generation of at least one of the feed drive system and the spindle drive system, by inputting at least one of operating information representing a state amount of the drive system related to servo control of the drive system and temperature information indicating the temperature of the drive system into a first deformation amount estimation model; a thermal displacement amount calculation unit that converts the first deformation amount into a thermal displacement amount, which is the relative displacement amount between the tool and the workpiece, using kinematic configuration information of the machine tool; and a correction command generation unit that generates a correction command to correct a position commanded to the feed drive system based on the thermal displacement amount.

9. The machine tool system described in claim 8, characterized in that the control device is provided with a second deformation amount estimation unit that calculates a second deformation amount, which is the deformation amount of the structural member caused by a temperature change in the environment in which the machine tool is installed, by inputting temperature information indicating the temperature of a structural member other than the feed drive system and the spindle drive system among the components of the machine tool into a second deformation amount estimation model, the thermal displacement amount calculation unit combines the second deformation amount with a thermal displacement amount converted from the first deformation amount, and the correction command generation unit generates the correction command for correcting the position to be commanded to the feed drive system based on the thermal displacement amount combined with the second deformation amount.

10. The machine tool system according to claim 9, further comprising a memory device for storing a plurality of deformation amount estimation models, and at least one of the first deformation amount estimation model and the second deformation amount estimation model is a deformation amount estimation model selected from the plurality of deformation amount estimation models.

11. A machining method comprising the steps of: machining the workpiece using a machine tool equipped with one or more feed drive systems for moving a tool and a workpiece relative to each other, and a spindle drive system for rotating the tool or the workpiece; calculating a first deformation amount, which is a deformation amount of the drive system, which is at least one of the feed drive system and the spindle drive system, caused by heat generation of the drive system, by inputting at least one of operating information representing a state quantity of the drive system and temperature information indicating the temperature of the drive system, into a first deformation amount estimation model; converting the first deformation amount into a thermal displacement amount, which is a relative displacement amount between the tool and the workpiece, using kinematic configuration information of the machine tool; and generating a correction command for correcting a position commanded to the feed drive system based on the thermal displacement amount.

Images