MACHINE TOOL, CONTROL METHOD, AND CONTROL PROGRAM

Abstract

A technique is provided for accurately estimating a characteristic value correlated with the flow resistance of a coolant in a tool. [Solution] The machine tool includes a spindle having a second passage connected to a first passage of a tool when the tool is attached, a pump for pumping coolant to a main passage connected to the second passage, an adjustment mechanism for adjusting the flow rate of the coolant in the main passage or its branch passages, a pressure sensor for detecting the discharge pressure of the coolant from the tool, a flow rate sensor for detecting the discharge amount, and a control unit. The control unit executes a process for acquiring information defining the relationship between the discharge pressure of the coolant from a discharge port of the tool, the discharge amount of the coolant from the discharge port, and a characteristic value correlating with the flow resistance of the coolant in the tool, and a process for estimating the characteristic value correlating with the flow resistance of the coolant in the machining tool based on the information, the detected discharge pressure, and the detected discharge amount.

Description

[Technical field]

[0001] The present disclosure relates to a machine tool, a control method, and a control program. [Background technology]

[0002] Japanese Patent Laid-Open Publication No. 2016-64462 (Patent Document 1) discloses a machine tool capable of machining a workpiece while discharging coolant from the tip of the tool. A spindle on which such a tool can be mounted is called a coolant-through spindle. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-64462 A Summary of the Invention [Problem to be solved by the invention]

[0004] A coolant passage is formed inside the tool used in the coolant-through spindle. The amount and pressure of the coolant discharged from the tool vary depending on a characteristic value that correlates with the flow resistance of the coolant inside the tool. The characteristic value is described in catalog information, but may not be accurate. Therefore, a technology for accurately estimating the characteristic value of a machining tool is desired.

[0005] Incidentally, Patent Document 1 does not disclose anything about estimating the size of the coolant outlet port in a machining tool. [Means for solving the problem]

[0006] In one example of the present disclosure, a machine tool capable of machining a workpiece using a machining tool having a first coolant passage formed therein is provided. The machine tool is configured to be able to mount the machining tool and includes a spindle having a second passage connected to the first passage when the machining tool is mounted, a pump for pumping coolant to a main passage connected to the second passage, an adjustment mechanism capable of adjusting the flow rate of the coolant in one or more branch passages branching from the main passage or in the main passage, a pressure sensor for detecting the discharge pressure of the coolant from the machining tool, a flow rate sensor for detecting the discharge amount of the coolant from the machining tool, and a control unit. The control unit executes a process of acquiring information defining a relationship between the discharge pressure of the coolant from a discharge port of the tool, the discharge amount of the coolant from the discharge port, and a characteristic value correlated with the flow resistance of the coolant in the tool, and a process of estimating a characteristic value correlated with the flow resistance of the coolant in the machining tool based on the information, the discharge pressure detected by the pressure sensor, and the discharge amount detected by the flow rate sensor.

[0007] In one example of the present disclosure, the characteristic value of the tool defined in the information is a size of an outlet of the tool. The characteristic value of the machining tool estimated in the estimating process is a size of an outlet of the machining tool.

[0008] In one example of the present disclosure, the control unit further executes a process of controlling the adjustment mechanism in accordance with the estimated size, and a process of controlling the pump after executing the control process.

[0009] In one example of the present disclosure, the branch flow path from the main flow path includes a first branch flow path and a second branch flow path. The adjustment mechanism includes a first valve provided in the first branch flow path and a second valve provided in the second branch flow path. The first valve is configured to at least switch whether or not the coolant in the main flow path is caused to flow to the first branch flow path by opening and closing the first valve. The second valve is configured to at least switch whether or not the coolant in the main flow path is caused to flow to the second branch flow path by opening and closing the second valve. In the process of controlling the adjustment mechanism, opening and closing of the first valve and opening and closing of the second valve are controlled.

[0010] In one example of the present disclosure, a maximum flow rate of the first branch flow channel when the first valve is opened is less than a maximum flow rate of the coolant of the second branch flow channel when the second valve is opened. In the process of controlling the adjustment mechanism, if the estimated size is smaller than a first threshold, the first valve is closed and the second valve is opened, if the estimated size is equal to or greater than the first threshold and smaller than a second threshold, the first valve is opened and the second valve is closed, if the estimated size is equal to or greater than the second threshold, both the first valve and the second valve are closed, and the first threshold is smaller than the second threshold.

[0011] In one example of the present disclosure, the process of controlling the pump includes feedforward control for controlling the pump without being based on the discharge pressure detected by the pressure sensor and the discharge rate detected by the flow rate sensor, and feedback control for controlling the pump so that the discharge pressure detected by the pressure sensor or the discharge rate detected by the flow rate sensor approaches a target value. In the process of controlling the pump, if the target value is smaller than a predetermined threshold, execution of the feedback control is started after execution of the feedforward control. If the target value is equal to or greater than the predetermined threshold, execution of the feedback control is started without execution of the feedforward control.

[0012] In one example of the present disclosure, the control unit includes a first control device capable of controlling the pump and a second control device different from the first control device. The estimating process is executed by the second control device.

[0013] In another example of the present disclosure, a method for controlling a machine tool capable of machining a workpiece using a machining tool having a first coolant passage formed therein is provided. The machine tool includes a spindle configured to be able to mount the machining tool and having a second passage connected to the first passage when the machining tool is mounted, a pump for pumping coolant to a main passage connected to the second passage, an adjustment mechanism capable of adjusting the flow rate of coolant in one or more branch passages branching from the main passage or in the main passage, a pressure sensor for detecting the discharge pressure of the coolant from the machining tool, and a flow rate sensor for detecting the discharge amount of the coolant from the machining tool. The control method includes a step of acquiring information defining a relationship between the discharge pressure of the coolant from a discharge port of the tool, the discharge amount of the coolant from the discharge port, and a characteristic value correlated with the flow resistance of the coolant in the tool, and a step of estimating a characteristic value correlated with the flow resistance of the coolant in the machining tool based on the information, the discharge pressure detected by the pressure sensor, and the discharge amount detected by the flow rate sensor.

[0014] In another example of the present disclosure, a control program for a machine tool capable of machining a workpiece using a machining tool having a first coolant passage formed therein is provided. The machine tool is configured to be able to mount the machining tool and includes a spindle having a second passage connected to the first passage when the machining tool is mounted, a pump for pumping coolant to a main passage connected to the second passage, an adjustment mechanism capable of adjusting the flow rate of the coolant in one or more branch passages branching from the main passage or in the main passage, a pressure sensor for detecting the discharge pressure of the coolant from the machining tool, and a flow rate sensor for detecting the discharge rate of the coolant from the machining tool. The control program causes the machine tool to execute a process of acquiring information defining a relationship between the discharge pressure of the coolant from a tool outlet, the discharge rate of the coolant from the outlet, and a characteristic value correlating with the flow rate of the coolant in the tool, and a process of estimating a characteristic value correlating with the flow rate of the coolant in the machining tool based on the information, the discharge pressure detected by the pressure sensor, and the discharge rate detected by the flow rate sensor.

[0015] The above and other objects, features, aspects and advantages of the present invention will become apparent from the following detailed description of the invention taken in conjunction with the accompanying drawings. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a diagram showing the appearance of a machine tool. [Diagram 2] FIG. 4 illustrates an example of a coolant supply mechanism. [Diagram 3] FIG. 13 is a diagram illustrating a process for estimating an aperture size. [Figure 4] FIG. 13 is a flowchart showing a calibration phase. [Diagram 5] FIG. 13 is a flowchart showing a calibration phase. [Figure 6] FIG. 4 is a diagram illustrating an example of a tool database. [Figure 7] It is a diagram showing a flowchart related to a processing phase. [Figure 8] It is a diagram showing a flowchart related to the process of step S300 shown in FIG. 7. [Figure 9] It is a diagram for explaining a second driving mode. [Figure 10] It is a diagram showing a flowchart related to the process of step S400 shown in FIG. 7. [Figure 11] It is a diagram showing an example of threshold information. [Figure 12] It is a diagram showing a flowchart related to the process of step S500 shown in FIG. 7. [Figure 13] It is a diagram showing an example of the hardware configuration of a CPU (Central Processing Unit) unit. [Figure 14] It is a diagram showing an example of the hardware configuration of a CNC (Computer Numerical Control) unit. [Figure 15] It is a diagram showing an example of the hardware configuration of an operation panel. [Figure 16] It is a diagram showing an example of an implementation form of a calibration program and a discharge program. [Figure 17] It is a diagram showing a coolant supply mechanism according to a modification.

Embodiments for Carrying Out the Invention

[0017] Hereinafter, each embodiment according to the present invention will be described with reference to the drawings. In the following description, the same parts and components are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed descriptions thereof will not be repeated. Note that each embodiment and each modification described below may be selectively combined as appropriate.

[0018] <A. Machine Tool 100> First, with reference to FIG. 1, a machine tool 100 according to an embodiment will be described. FIG. 1 is a diagram showing the appearance of the machine tool 100.

[0019] In this specification, the term "machine tool" is a concept that includes various devices that have the function of machining a workpiece. Machine tool 100 may be a horizontal machining center or a vertical machining center. Alternatively, machine tool 100 may be a lathe, or other cutting machine, grinding machine, multi-tasking machine, five-axis machine, or the like. Furthermore, machine tool 100 is not limited to one that performs only removal machining. Machine tool 100 may be one that performs additional machining in addition to removal machining.

[0020] Machine tool 100 has a tool storage section 40A and a processing machine body 40B. Each of tool storage section 40A and processing machine body 40B is partitioned by a cover.

[0021] The tool storage section 40A is provided with a magazine 150 and an ATC (Automatic Tool Changer) 160. The processing machine body 40B is provided with a spindle head 170.

[0022] The spindle head 170 includes a spindle tube 175 and a spindle 180. The spindle 180 is supported by the spindle tube 175 so as to be rotatable about its axial direction as the center of rotation. The rotation of the spindle 180 is achieved by a drive mechanism such as a motor, for example.

[0023] A tool selected from the magazine 150 is mounted on the spindle 180. More specifically, the machine tool 100 drives the magazine 150 and moves a tool (hereinafter also referred to as a "processing tool") corresponding to the processing step to the first tool change position. Further, the machine tool 100 drives the spindle head 170 and moves the tool (hereinafter also referred to as a "used tool") mounted on the spindle 180 to the second tool change position. Thereafter, the ATC 160 exchanges the processing tool waiting at the first tool change position with the used tool waiting at the second tool change position. The tool exchange is performed through a door D provided in a partition between the processing machine main body 40B and the tool storage section 40A. The door D is a slide-type door and is opened and closed by a drive source such as a motor. Thereafter, the machine tool 100 processes the workpiece using the processing tool mounted on the spindle 180.

[0024] In addition, the machine tool 100 is provided with an operation panel 400. The operation panel 400 includes a display 405 for displaying various information related to processing and operation keys 406 for receiving various operations on the machine tool 100.

[0025] <B. Coolant Supply Mechanism> Next, with reference to FIG. 2, the coolant supply mechanism in the machine tool 100 will be described. FIG. 2 is a diagram showing an example of the coolant supply mechanism.

[0026] The machine tool 100 includes a control unit 50, a coolant tank 52, a motor driver 54, a motor 55, a pump 56, an adjustment mechanism 58, a pressure sensor 59, a flow sensor 60, and a spindle 180.

[0027] For the sake of convenience of explanation, the side of the pump 56 in the coolant flow path is also referred to as the "upstream side", and the side of the spindle 180 in the coolant flow path is also referred to as the "downstream side".

[0028] Inside the machine tool 100, a main coolant flow path F1 and a branch flow path F2 are provided.

[0029] One end of the main flow path F1 is connected to the coolant tank 52. The other end of the main flow path F1 is connected to a communication passage L2 (second passage) formed in the main shaft 180. The communication passage L2 passes through the inside of the main shaft 180 along the axial direction of the main shaft 180.

[0030] Various types of tools can be attached to the spindle 180. In the example of Fig. 2, a machining tool T having a through passage L1 (first passage) for coolant formed therein is attached to the spindle 180. The through passage L1 extends from a connection surface between the machining tool T and the spindle 180 to the tip of the machining tool T, and penetrates the machining tool T along the axial direction of the spindle 180.

[0031] The discharge port of the through passage L1 formed in the machining tool T is not limited to being formed on the base end surface or the tip end surface of the machining tool T, and may be formed, for example, on the side surface of the machining tool T. In addition, although the example of Fig. 2 shows a machining tool T having one discharge port, the machining tool T may have multiple discharge ports. The diameter of the discharge port of the machining tool T is, for example, 5 mm or less.

[0032] When the machining tool T is attached to the spindle 180, the through passage L1 is connected to a communication passage L2 inside the spindle 180. That is, one end of the communication passage L2 is connected to the through passage L1. The other end of the communication passage L2 can be connected to the main flow path F1.

[0033] The branch flow passage F2 is a flow passage branched from the main flow passage F1. The branch flow passage F2 is a path for returning a part of the coolant flowing from the main flow passage F1 to the spindle 180. The number of branch flow passages F2 branching from the main flow passage F1 may be one or more. In the example of Fig. 2, two branch flow passages F2A and F2B branch off from the main flow passage F1.

[0034] The branch flow path F2A branches off from the main flow path F1 at a branch point P2A. In other words, one end of the branch flow path F2A is connected to the main flow path F1. The other end of the branch flow path F2A may be connected to any other destination. In the example of FIG. 2, the other end of the branch flow path F2A is connected to the coolant tank 52. As another example, the other end of the branch flow path F2A may be connected to a coolant tank other than the coolant tank 52.

[0035] The branch flow passage F2B branches off from the main flow passage F1 at a branch point P2B. In other words, one end of the branch flow passage F2B is connected to the main flow passage F1. The other end of the branch flow passage F2B may be connected to any other destination. In the example of FIG. 2, the other end of the branch flow passage F2B is connected to the coolant tank 52. As another example, the other end of the branch flow passage F2B may be connected to a coolant tank other than the coolant tank 52. The branch flow passage F2B is located downstream of the branch point P2A.

[0036] The control unit 50 controls various devices within the machine tool 100. The device configuration of the control unit 50 is arbitrary. The control unit 50 may be configured as a single control unit, or may be configured as multiple control units. As an example, the control unit 50 includes at least one of a PLC (Programmable Logic Controller), a CNC, and the above-mentioned operation panel 400. In addition, the control unit 50 may include a magazine server (not shown) that stores information related to the above-mentioned magazine 150.

[0037] The pump 56 is provided in the main flow path F1 and pumps coolant from the coolant tank 52 to the main flow path F1. The force for pumping the coolant is controlled by the control unit 50. The coolant pumped by the pump 56 flows through the main flow path F1, the communication path L2, and the through path L1 in that order, and is discharged from the tip of the machining tool T to the workpiece to be machined. The spindle 180 having such a coolant discharge function is also called a coolant-through spindle.

[0038] More specifically, a motor 55 is connected to the pump 56. The motor 55 is driven by a motor driver 54. The motor driver 54 is composed of a control circuit, an inverter, and the like. The motor driver 54 receives a control signal from the control unit 50 and outputs an AC current having a frequency corresponding to the control signal to the motor 55. This changes the rotation speed of the motor 55, thereby controlling the flow rate of the coolant pumped to the main flow path F1.

[0039] The adjustment mechanism 58 is a mechanism capable of adjusting the flow rate of the coolant in the branch flow path F2 branching off from the main flow path F1. The configuration of the adjustment mechanism 58 is arbitrary. As an example, when one branch flow path F2 branches off from the main flow path F1, the adjustment mechanism 58 is composed of one or more variable valves capable of adjusting the opening degree in response to a control signal. As another example, the adjustment mechanism 58 is composed of a plurality of fixed-volume valves capable of controlling the opening and closing in response to a control signal.

[0040] In the example of FIG. 2, the adjustment mechanism 58 is made up of two orifice valves 58A and 58B (first and second valves) which are metered flow valves.

[0041] Furthermore, the adjustment mechanism 58 is not limited to a configuration that adjusts the flow rate of the coolant in the branch passage F2. As another example, the adjustment mechanism 58 may be configured to adjust the flow rate of the coolant in the main passage F1.

[0042] The orifice valve 58A is provided in the branch flow passage F2A and adjusts the flow of the coolant in the branch flow passage F2A. The orifice valve 58A has an orifice FRA. The orifice FRA is provided, for example, downstream of the orifice valve 58A and functions as a fluid resistance for the coolant flowing through the branch flow passage F2A. In other words, the orifice FRA is configured to be able to switch whether or not to apply fluid resistance to the coolant flowing through the branch flow passage F2A by opening and closing the orifice valve 58A.

[0043] The orifice valve 58A is switched between opening and closing in response to a control command from the control unit 50. Thus, the orifice valve 58A is configured to at least be able to switch whether or not the coolant in the main flow path F1 is allowed to flow to the branch flow path F2A branching from the main flow path F1. When the orifice valve 58A is in a closed state, the flow of the coolant in the branch flow path F2A is stopped. On the other hand, when the orifice valve 58A is in an open state, the coolant is returned from the main flow path F1 to the branch flow path F2A. The opening degree of the orifice valve 58A may be adjustable or may be constant.

[0044] The orifice valve 58B is provided in the branch flow passage F2B and adjusts the flow of the coolant in the branch flow passage F2B. The orifice valve 58B has an orifice FRB. The orifice FRB is provided, for example, downstream of the orifice valve 58B and functions as a fluid resistance for the coolant flowing through the branch flow passage F2B. In other words, the orifice FRB is configured to be able to switch whether or not to apply fluid resistance to the coolant flowing through the branch flow passage F2B by opening and closing the orifice valve 58B.

[0045] The orifice valve 58B is switched between opening and closing in response to a control command from the control unit 50. Thus, the orifice valve 58B is configured to at least be able to switch whether or not the coolant in the main flow path F1 is allowed to flow to the branch flow path F2B branching off from the main flow path F1. When the orifice valve 58B is in a closed state, the flow of the coolant in the branch flow path F2B is stopped. On the other hand, when the orifice valve 58B is in an open state, the coolant is returned from the main flow path F1 to the branch flow path F2B. The opening degree of the orifice valve 58B may be adjustable or may be constant.

[0046] Typically, the maximum flow rate of the coolant in the branch flow passage F2A when the orifice valve 58A is opened is different from the maximum flow rate of the coolant in the branch flow passage F2B when the orifice valve 58B is opened. That is, the maximum capacity (Cv value) of the orifice valve 58A is different from the maximum capacity (Cv value) of the orifice valve 58B.

[0047] For example, the diameter of the orifice FRA on the orifice valve 58A side is smaller than the diameter of the orifice FRB on the orifice valve 58B side. As a result, the maximum flow rate of the coolant in the branch flow passage F2A when the orifice valve 58A is opened is smaller than the maximum flow rate of the coolant in the branch flow passage F2B when the orifice valve 58B is opened.

[0048] Hereinafter, the orifice valve 58A having a smaller orifice diameter is also referred to as a "small-capacity orifice valve 58A." On the other hand, the orifice valve 58B having a larger orifice diameter is also referred to as a "large-capacity orifice valve 58B."

[0049] The pressure sensor 59 detects the discharge pressure of the coolant from the machining tool T. In the example of Fig. 2, the pressure sensor 59 is provided downstream of the branch point P2A and the branch point P2B and upstream of the spindle 180. The discharge pressure detected by the pressure sensor 59 is output to the control unit 50.

[0050] The flow rate sensor 60 detects the amount of coolant discharged from the machining tool T per unit time. In the example of Fig. 2, the flow rate sensor 60 is provided downstream of the branch points P2A, P2B and upstream of the spindle 180. The discharge amount detected by the flow rate sensor 60 is output to the control unit 50.

[0051] Note that as long as the flow rate sensor 60 can detect the discharge amount of the coolant discharged from the processing tool T per unit time, the position where the flow rate sensor 60 is provided is not limited to the main flow path F1. As an example, the flow rate sensor 60 may be provided in each of the branch flow paths F2A and F2B. In this case, the control unit 50 calculates the discharge amount of the coolant discharged from the processing tool T by subtracting the coolant flow rates in the branch flow paths F2A and F2B from the discharge flow rate of the pump 56.

[0052] <C. Overview> The machine tool 100 according to the embodiment has a function of estimating a characteristic value correlated with the flow path resistance of the coolant in the processing tool T. The characteristic value may be the size of the coolant discharge port in the processing tool T (hereinafter also referred to as "opening size"), or may be the coolant fluid resistance itself in the processing tool T.

[0053] Hereinafter, as an example of the characteristic value, the "opening size" will be taken as an example for explanation, but the estimation target is not limited to the opening size.

[0054] Note that the above opening size may be indicated by the diameter of the coolant discharge port in the processing tool T, may be indicated by the area of the discharge port, or may be indicated by another value correlated with the size of the discharge port. Further, the diameter may be indicated by the diameter or the radius. Furthermore, when a plurality of discharge ports are formed in the processing tool T, the above opening size may be indicated by the diameter or area of any one of the discharge ports, or may be indicated by the average diameter or average area of the plurality of discharge ports.

[0055] FIG. 3 is a diagram schematically showing the process of estimating the opening size. Hereinafter, the outline of the estimation process will be described.

[0056] As shown in FIG. 3, the control unit 50 of the machine tool 100 acquires the correlation information 124. The correlation information 124 defines the relationship between the discharge pressure 125A, the discharge amount 125B, and the opening size 125C.

[0057] Discharge pressure 125A indicates the pressure of the coolant from the tool outlet, for example in megapascals (i.e., “MPa”).

[0058] The discharge amount 125B indicates the flow rate of the coolant discharged from the outlet of the tool per unit time. The unit of the flow rate is, for example, liters per second (i.e., "L / s").

[0059] The opening size 125C indicates the size of the opening of the outlet of the tool. The unit of the opening size is, for example, millimeters (i.e., "mm").

[0060] The control unit 50 estimates the opening size of the machining tool T based on the correlation information 124, the discharge pressure of the machining tool T to be estimated, and the discharge rate of the machining tool T. The discharge pressure of the machining tool T is acquired from the pressure sensor 59 described above. The discharge rate of the machining tool T is acquired from the flow rate sensor 60 described above.

[0061] As an example, the control unit 50 identifies a discharge pressure that is closest to the detection value of the pressure sensor 59 among the discharge pressures 125A defined in the correlation information 124. Next, the control unit 50 identifies a discharge rate that is closest to the detection value of the flow rate sensor 60 among the discharge rates 125B defined in the correlation information 124. After that, the control unit 50 identifies an opening size that is associated with a combination of the identified discharge pressure and the identified discharge rate as an estimated value among the opening sizes 125C defined in the correlation information 124.

[0062] In this manner, the control unit 50 estimates the opening size of the machining tool T from the relationship between the discharge pressure from the machining tool T and the discharge amount from the machining tool T. This allows the machine tool 100 to accurately estimate the discharge port of the machining tool T.

[0063] In the above, an example has been described in which the opening size of the machining tool T is estimated using the correlation information 124 in table format, but the data structure of the correlation information 124 is not limited to the table format. As an example, the correlation information 124 may be defined by a predetermined correlation formula. In this case, the correlation information 124 is defined by a correlation formula that at least indicates the relationship between the coolant discharge pressure, the coolant discharge amount, and the tool opening size. More specifically, the calculation formula is expressed by the following formula (1).

[0064] Q = CπD2 / 4√(2gP / γ) (1) "Q" in equation (1) indicates the coolant flow rate (i.e., the amount of coolant discharged). "C" indicates a correction coefficient. "C" is a constant. "D" indicates the tool opening size (for example, the diameter of the coolant discharge port). "g" indicates the gravitational acceleration. "g" is a constant. "P" indicates the coolant discharge pressure. "γ" indicates the density of the liquid. "γ" may be a constant or may be detected by a sensor or the like.

[0065] <D.キャリブレーションフェーズ> The estimation process of the opening size described with reference to Fig. 3 is executed in a calibration phase before machining of the workpiece. That is, the calibration phase is an adjustment phase that is performed before the machining phase.

[0066] In the calibration phase, various setting parameters used in the processing phase are optimized. One example of the setting parameters is the aperture size estimated in the process shown in Fig. 3. Other examples include setting parameters related to the pump 56, setting parameters related to the adjustment mechanism 58, etc.

[0067] By optimizing various setting parameters in the calibration phase, the machine tool 100 can machine a workpiece with an appropriate discharge pressure or an appropriate discharge amount in the machining phase. As a result, the start-up time from when the pump 56 starts to be driven until the coolant discharge pressure / discharge amount becomes stable is shortened.

[0068] The control flow of the calibration phase will be described below with reference to FIGS.

[0069] Figures 4 and 5 are diagrams showing a flowchart relating to the calibration phase. The processes shown in Figures 4 and 5 are executed by control unit 50 of machine tool 100. In another aspect, a part or the whole of the processes shown in Figures 4 and 5 may be executed by circuit elements or other hardware.

[0070] In step S110, the control unit 50 judges whether or not an instruction to perform calibration has been received. The instruction to perform calibration is issued, for example, by an operator operating a screen. At this time, the operator selects a tool to be calibrated. If the control unit 50 judges that an instruction to perform calibration has been received (YES in step S110), the control unit 50 switches control to step S112. If not (NO in step S112), the control unit 50 executes the process of step S110 again.

[0071] Next, in step S112, the control unit 50 controls the ATC 160 to mount, on the spindle 180, the machining tool T to be calibrated, selected by the operator.

[0072] Next, in step S114, the control unit 50 opens the orifice valve 58A having the smaller orifice diameter (ie, the small-capacity orifice valve 58A) and closes the orifice valve 58B having the larger orifice diameter (ie, the large-capacity orifice valve 58B).

[0073] Next, in step S116, the control unit 50 discharges the coolant at a predetermined target discharge pressure. The discharge control is realized by feedback control. More specifically, the control unit 50 controls the pump 56 so that the discharge pressure detected by the pressure sensor 59 approaches the predetermined target discharge pressure. The feedback control may be realized by PID (Proportional-Integral-Differential) control, PI (Proportional-Integral) control, or PD (Proportional-Differential) control. The control unit 50 switches the control from step S116 to step S120 based on the fact that the discharge pressure of the coolant has stabilized.

[0074] Thereafter, in steps S120 and S122, the control unit 50 judges whether the current discharge pressure is within the target range. The target range is defined by a threshold value th1 obtained by subtracting a predetermined value from the target discharge pressure in step S116, and a threshold value th2 obtained by adding a predetermined value to the target discharge pressure. The fact that the current discharge pressure is not within the target range means that the coolant discharge pressure cannot be kept within the target range with the current open / closed state of the orifice valves 58A and 58B.

[0075] One of the reasons why the coolant discharge pressure cannot be within the target range is that the minimum drive frequency and the maximum drive frequency of the pump 56 are determined. That is, the pump 56 needs to be driven at a predetermined minimum drive frequency or higher (e.g., 15 Hz or higher) and at a predetermined maximum drive frequency or lower (e.g., 60 Hz or lower). Therefore, depending on the current open / closed state of the orifice valves 58A and 58B, the coolant discharge pressure does not fall within the target range. Therefore, in steps S120 and S122, the control unit 50 determines whether the current discharge pressure is within the target range.

[0076] More specifically, in step S120, the control unit 50 determines whether the current discharge pressure is less than the threshold th1. If the control unit 50 determines that the current discharge pressure is less than the threshold th1 (YES in step S120), the control unit 50 switches control to step S124. If not (NO in step S120), the control unit 50 switches control to step S122.

[0077] Next, in step S122, the control unit 50 judges whether the current discharge pressure is equal to or greater than the threshold th2. The threshold th2 is greater than the threshold th1. If the control unit 50 judges that the current discharge pressure is equal to or greater than the threshold th2 (YES in step S122), the control unit 50 switches control to step S134. If not (NO in step S122), the control unit 50 switches control to step S146.

[0078] Next, in step S124, the control unit 50 closes both of the orifice valves 58A and 58B, thereby causing the discharge pressure of the pump 56 to increase more than when step S120 was executed.

[0079] Next, in step S134, the control unit 50 closes the small-capacity orifice valve 58A and opens the large-capacity orifice valve 58B, causing the discharge pressure of the pump 56 to be lower than when step S122 was executed.

[0080] Next, in step S140, the control unit 50 determines whether the current discharge pressure falls within the target range by the opening / closing control of the orifice valves 58A, 58B in step S124. More specifically, the control unit 50 determines whether the current discharge pressure is less than the threshold value th1. If the control unit 50 determines that the current discharge pressure is less than the threshold value th1 (YES in step S140), it switches control to step S142. If not (NO in step S140), the control unit 50 switches control to step S146.

[0081] Next, in step S142, the control unit 50 stores a predetermined value as a setting value for the current machining tool T, assuming that the discharge pressure cannot be brought into the target range even if the open / closed states of the orifice valves 58A, 58B are changed. The setting value is associated with the identifier of the current machining tool T and written to the tool database 126 described below. As an example, the maximum frequency (e.g., 60 Hz) is written to the tool database 126 as a recommended value for the frequency of the pump 56. In addition, the current open / closed states of each of the orifice valves 58A, 58B are written to the tool database 126. Furthermore, for other setting parameters (e.g., the opening size and discharge amount of the machining tool T, etc.), specified values ​​are used in the tool database 126.

[0082] Next, in step S146, the control unit 50 acquires the current discharge amount of coolant from the flow rate sensor 60 described above, assuming that the discharge pressure of the coolant falls within the target range in the current open / closed states of the orifice valves 58A, 58B.

[0083] Next, in step S148, the control unit 50 acquires the above-mentioned correlation information 124. Thereafter, the control unit 50 estimates the opening size of the machining tool T based on the correlation information 124, the current discharge pressure, and the current discharge amount. The estimation process is as described above, and therefore the description thereof will not be repeated.

[0084] Next, in step S150, the control unit 50 stores various current setting values. The setting values ​​stored in step S150 include the opening size estimated in step S148 and a recommended value related to the coolant discharge rate. The recommended value of the discharge rate is, for example, a value obtained by multiplying the discharge rate acquired in step S146 by a predetermined percentage.

[0085] Each setting value is written, for example, to the tool database 126 shown in Fig. 6. Fig. 6 is a diagram showing an example of the tool database 126.

[0086] The tool database 126 associates, for each machining tool capable of discharging coolant, an identifier for the machining tool, an opening size for the machining tool, a recommended value for the amount of coolant discharged, a recommended value for the driving frequency of the pump 56, and a recommended value for the open / closed state of each of the orifice valves 58A, 58B.

[0087] The tool identifier defined in the tool database 126 is information for uniquely identifying a tool. The identifier is assigned in advance to each tool. As an example, the identifier may be defined by a tool number such as an ID (Identification) or may be defined by a tool name.

[0088] 5, in step S160, the control unit 50 determines whether the recommended discharge rate written in the tool database 126 in step S150 is less than a threshold th3. If the control unit 50 determines that the recommended discharge rate is less than the threshold th3 (YES in step S160), the control unit 50 switches control to step S162. If not (NO in step S160), the control unit 50 switches control to step S170.

[0089] In step S162, the control unit 50 closes the small-capacity orifice valve 58A and opens the large-capacity orifice valve 58B.

[0090] In step S170, the control unit 50 determines whether the recommended discharge rate written in the tool database 126 in step S150 is equal to or greater than a threshold th4. The threshold th4 is greater than the threshold th3. If the control unit 50 determines that the recommended discharge rate is equal to or greater than the threshold th4 (YES in step S170), the control unit 50 switches control to step S172. If not (NO in step S170), the control unit 50 switches control to step S174.

[0091] In step S172, the control unit 50 closes both of the orifice valves 58A and 58B.

[0092] In step S174, the control unit 50 opens the small capacity orifice valve 58A and closes the large capacity orifice valve 58B.

[0093] In step S176, the control unit 50 discharges the coolant at the recommended discharge amount. The discharge control is realized by feedback control. More specifically, the control unit 50 controls the pump 56 so that the discharge amount detected by the flow rate sensor 60 approaches the recommended discharge amount. The feedback control may be realized by PID control, PI control, or PD control. The control unit 50 switches the control from step S176 to step S178 based on the fact that the discharge amount of the coolant has stabilized.

[0094] In step S178, the control unit 50 obtains the current drive frequency of the pump 56. The drive frequency is obtained, for example, from the motor driver 54 described above.

[0095] In step S180, the control unit 50 acquires the current open / closed state of each of the orifice valves 58A, 58B.

[0096] In step S182, the control unit 50 stores the current various setting values ​​as recommended setting values. The setting values ​​stored in step S182 include the drive frequency acquired in step S178 and the open / closed states of the orifice valves 58A and 58B acquired in step S180. Each setting value is written to the tool database 126 described above.

[0097] In the above steps S160 and S170, an example of comparing the recommended discharge amount with the threshold values th3 and th4 has been described. However, alternative processing may be executed. As an example, the recommended discharge amount calculated in step S150 changes according to the opening size of the processing tool T. Therefore, in steps S160 and S170, instead of the recommended discharge amount, the opening size estimated in step S148 may be compared with the threshold values th'3 and th'4.

[0098] More specifically, the recommended discharge amount being less than the threshold value th3 means that the opening size of the current processing tool T is small. Also, the recommended discharge amount being equal to or greater than the threshold value th3 and less than the threshold value th4 means that the opening size of the current processing tool T is medium. Furthermore, the recommended discharge amount being equal to or greater than the threshold value th4 means that the opening size of the current processing tool T is large.

[0099] Therefore, in step S160, it may be determined whether the opening size estimated in step S148 is less than the threshold value th'3. Also, in step S170, it may be determined whether the opening size estimated in step S148 is equal to or greater than the threshold value th'4.

[0100] In the above example, an example of performing calibration for one processing tool T has been described. However, calibration may be performed for a plurality of processing tools T. In this case, the control unit 50 executes the calibration process shown in FIGS. 4 and 5 for each processing tool T.

[0101] <E. Processing Phase> Next, with reference to FIGS. 7 to 12, the control flow of the processing phase executed after the above-described calibration phase will be described. FIG. 7 is a diagram showing a flowchart related to the processing phase.

[0102] The process shown in Fig. 7 is executed by control unit 50 of machine tool 100. In another aspect, some or all of the process shown in Fig. 7 may be executed by circuit elements or other hardware.

[0103] In the machining phase, the control unit 50 performs machining of the workpiece in a discharge manner according to the discharge mode. The discharge mode may be set in advance or may be set arbitrarily by the operator. Examples of the settable discharge modes include a recommended control mode, a discharge pressure control mode, and a discharge amount control mode.

[0104] The recommended control mode is a mode in which the discharge of coolant from the machining tool T is controlled in accordance with the recommended setting value stored in the calibration phase. The discharge pressure control mode is a mode in which the machine tool 100 is controlled so that the discharge pressure of the coolant from the machining tool T becomes a target value specified by an operator. The discharge amount control mode is a mode in which the machine tool 100 is controlled so that the discharge amount of coolant from the machining tool T approaches a specified target value.

[0105] In step S210, the control unit 50 judges whether or not the calibrated machining tool T has been attached to the spindle 180. When the control unit 50 judges that the calibrated machining tool T has been attached to the spindle 180 (YES in step S210), the control unit 50 switches control to step S220. When the control unit 50 judges that the calibrated machining tool T has been attached to the spindle 180 (YES in step S210), the control unit 50 switches control to step S600.

[0106] Next, in step S220, the control unit 50 judges whether the currently set discharge mode is the recommended control mode. If it is judged that the currently set discharge mode is the recommended control mode (YES in step S220), the control unit 50 switches the control to step S300. If not (NO in step S220), the control unit 50 switches the control to step S230.

[0107] Next, in step S230, the control unit 50 judges whether the currently set discharge mode is the discharge pressure control mode. If it is judged that the currently set discharge mode is the discharge pressure control mode (YES in step S230), the control is switched to step S400. If not (NO in step S230), the control unit 50 switches the control to step S500.

[0108] Next, in step S300, the control unit 50 executes a process for discharging coolant in the recommended control mode. The process in step S300 will be described in detail later.

[0109] Next, in step S400, the control unit 50 executes a coolant discharge process in the discharge pressure control mode. The process of step S400 will be described in detail later.

[0110] Next, in step S500, the control unit 50 executes a coolant discharge process in the discharge amount control mode. The process of step S500 will be described in detail later.

[0111] Next, in step S600, the control unit 50 executes machining of the workpiece W while discharging coolant from the machining tool T in accordance with a machining program designed in advance.

[0112] (E1. Recommended control mode) Next, the discharge process in the recommended control mode shown in step S300 in Fig. 7 will be described with reference to Fig. 8. Fig. 8 is a diagram showing a flowchart relating to the process in step S300.

[0113] In step S302, the control unit 50 refers to the above-mentioned tool database 126 to acquire recommended setting values ​​associated with the current machining tool T. The acquired setting values ​​include the open / closed states of the orifice valves 58A and 58B, the recommended discharge amount, and the recommended drive frequency.

[0114] Next, in step S304, the control unit 50 controls the open / close states of each of the orifice valves 58A and 58B in accordance with the recommended open / close states acquired in step S302.

[0115] Next, in step S306, the control unit 50 controls the pump 56 according to the recommended discharge amount acquired in step S302.

[0116] Preferably, the control unit 50 changes the driving mode of the pump 56 according to the recommended discharge amount. The driving mode includes a first driving mode in which feedback control is started from the beginning, and a second driving mode in which feedback control is started after feedforward control.

[0117] In the feedback control, the control unit 50 controls the pump 56 so that the discharge amount detected by the flow rate sensor 60 approaches the recommended discharge amount. The feedback control may be realized by PID control, PI control, or PD control.

[0118] In contrast, in the feedforward control, the control unit 50 controls the pump 56 not based on the discharge amount detected by the flow rate sensor 60. At this time, the pump 56 is driven at the recommended drive frequency acquired in step S302.

[0119] Fig. 9 is a diagram for explaining the second driving mode. The horizontal axis of the graph shown in Fig. 9 represents time. The vertical axis of the graph shown in Fig. 9 represents the output frequency of the AC current output from the inverter provided in the motor driver 54 described above.

[0120] The control unit 50 starts a feedforward process based on the recommended drive frequency at timing T0 when the drive of the pump 56 is started. This causes the output frequency of the inverter provided in the motor driver 54 to increase. The control unit 50 starts a feedback process at timing T1 when the output frequency exceeds a predetermined frequency fth. That is, after timing T1, the control unit 50 adjusts the drive frequency of the pump 56 so that the discharge rate detected by the flow rate sensor 60 approaches the recommended discharge rate.

[0121] As described above, the control unit 50 changes the driving mode at the start of driving the pump 56 in accordance with the recommended discharge amount. This shortens the time until the discharge amount from the machining tool T becomes stable.

[0122] (E2. Discharge pressure control mode) Next, the discharge process in the discharge pressure control mode shown in step S400 in Fig. 7 will be described with reference to Fig. 10 and Fig. 11. Fig. 10 is a diagram showing a flowchart relating to the process in step S400.

[0123] In step S402, the control unit 50 acquires a target discharge pressure. The target discharge pressure is set in advance by, for example, an operator. The operator can set the target discharge pressure in the range of, for example, 1.0 MPa or more and 10.0 MPa or less. The setting is accepted, for example, by the above-mentioned operation panel 400.

[0124] In step S404, the control unit 50 refers to the above-mentioned tool database 126 to obtain the opening size associated with the current machining tool T.

[0125] In step S406, the control unit 50 controls the opening and closing of the orifice valves 58A, 58B based on the opening size acquired in step S404. At this time, the control unit 50 controls the opening and closing of the orifice valves 58A, 58B so that the coolant flow rate from the main flow path F1 to the branch flow path F2 decreases as the opening size of the machining tool T increases. As an example, the open / closed states of the orifice valves 58A, 58B are determined with reference to threshold information 128 shown in FIG.

[0126] Fig. 11 is a diagram showing an example of the threshold information 128. As shown in Fig. 11, the threshold information 128 associates a lower limit threshold for the opening size and an upper limit threshold for the opening size with each target discharge pressure.

[0127] As a more specific process, the control unit 50 refers to the threshold information 128 and acquires a lower limit threshold and an upper limit threshold corresponding to the target discharge pressure acquired in step S402. Then, when the opening size acquired in step S404 is less than the lower limit threshold, the control unit 50 closes the small capacity orifice valve 58A and opens the large capacity orifice valve 58B. When the opening size is equal to or greater than the lower limit threshold and less than the upper limit threshold, the control unit 50 opens the small capacity orifice valve 58A and closes the large capacity orifice valve 58B. When the opening size is equal to or greater than the upper limit threshold, the control unit 50 closes both the small capacity orifice valve 58A and the large capacity orifice valve 58B.

[0128] In the above, an example has been described in which the lower limit threshold and the upper limit threshold for the machining tool T are changed depending on the target discharge pressure, but the lower limit threshold and the upper limit threshold may be constant regardless of the target discharge pressure.

[0129] 10 again, in step S408, the control unit 50 executes the opening / closing control of the orifice valves 58A, 58B, and then starts driving the pump 56. At this time, the control unit 50 controls the pump 56 according to the target discharge pressure acquired in step S402.

[0130] Preferably, the control unit 50 changes the driving mode of the pump 56 in response to the target discharge pressure. The driving mode includes the above-mentioned first driving mode in which the feedback control is started from the beginning, and the above-mentioned second driving mode in which the feedback control is started after the feedforward control is executed.

[0131] In the feedback control, the control unit 50 controls the pump 56 so that the discharge amount detected by the pressure sensor 59 approaches the target discharge pressure. The feedback control may be realized by PID control, PI control, or PD control.

[0132] On the other hand, in the feedforward control, the control unit 50 controls the pump 56 not based on the discharge amount detected by the pressure sensor 59. At this time, the pump 56 is driven at a predetermined drive frequency.

[0133] The control process according to the second driving mode will be described. The control unit 50 starts a feedforward process based on a predetermined driving frequency at the timing when the driving of the pump 56 is started. This causes the output frequency of the AC current output from the motor driver 54 to increase. The control unit 50 starts a feedback process at the timing when the output frequency exceeds a predetermined frequency. That is, the control unit 50 adjusts the driving frequency of the pump 56 so that the discharge pressure detected by the pressure sensor 59 approaches the target discharge pressure.

[0134] (E3. Discharge volume control mode) Next, the discharge process in the discharge amount control mode shown in step S500 in Fig. 7 will be described with reference to Fig. 12. Fig. 12 is a diagram showing a flowchart relating to the process in step S500.

[0135] In step S502, the control unit 50 acquires a target discharge amount. The target discharge amount is set in advance by, for example, an operator. The operator can set the target discharge amount within a range of, for example, 1.0 L / s or more and 25.0 L / s or less. The setting is accepted, for example, by the above-mentioned operation panel 400.

[0136] In step S560, the control unit 50 judges whether the target discharge amount is less than the threshold th3. If the control unit 50 judges that the target discharge amount is less than the threshold th3 (YES in step S560), the control unit 50 switches control to step S562. If not (NO in step S560), the control unit 50 switches control to step S570.

[0137] In step S562, the control unit 50 closes the small capacity orifice valve 58A and opens the large capacity orifice valve 58B.

[0138] In step S570, the control unit 50 judges whether the target discharge amount is equal to or greater than a threshold value th4. The threshold value th4 is greater than the threshold value th3. If the control unit 50 judges that the target discharge amount is equal to or greater than the threshold value th4 (YES in step S570), the control unit 50 switches control to step S572. If not (NO in step S570), the control unit 50 switches control to step S574.

[0139] In step S572, the control unit 50 closes both of the orifice valves 58A and 58B.

[0140] In step S574, the control unit 50 opens the small capacity orifice valve 58A and closes the large capacity orifice valve 58B.

[0141] In step S576, after executing the opening / closing control of the orifice valves 58A, 58B, the control unit 50 starts driving the pump 56. At this time, the control unit 50 controls the pump 56 according to the target discharge amount acquired in step S502.

[0142] Preferably, the control unit 50 changes the driving mode of the pump 56 according to the target discharge amount. The driving mode includes the above-described first driving mode in which feedback control is started from the beginning and the above-described second driving mode in which feedback control is started after the execution of feedforward control.

[0143] In the feedback control in step S576, the control unit 50 controls the pump 56 so that the discharge amount detected by the flow rate sensor 60 approaches the target discharge amount. The feedback control may be realized by PID control, may be realized by PI control, or may be realized by PD control.

[0144] On the other hand, in feedforward control, the control unit 50 controls the pump 56 without relying on the discharge amount detected by the flow rate sensor 60.

[0145] The control process according to the second driving mode will be described. At the timing when the control unit 50 starts driving the pump 56, it starts a feedforward process based on a predetermined driving frequency. As a result, the output frequency of the inverter provided in the motor driver 54 increases. The control unit 50 starts feedback processing at the timing when the output frequency exceeds a predetermined frequency. That is, after that timing, the control unit 50 adjusts the driving frequency of the pump 56 so that the discharge amount detected by the flow rate sensor 60 approaches the target discharge amount.

[0146] <Hardware Configuration of the F.CPU Unit 20> Next, with reference to FIG. 13, the hardware configuration of the CPU unit 20, which is an example of the above-described control unit 50, will be described. FIG. 13 is a diagram showing an example of the hardware configuration of the CPU unit 20.

[0147] The CPU unit 20 includes a control circuit 101, a read only memory (ROM) 102, a random access memory (RAM) 103, communication interfaces 104 and 105, and an auxiliary storage device 120. These components are connected to an internal bus 109.

[0148] The control circuit 101 is configured, for example, by at least one integrated circuit. The integrated circuit may be configured, for example, by at least one CPU, at least one GPU (Graphics Processing Unit), at least one ASIC (Application Specific Integrated Circuit), at least one FPGA (Field Programmable Gate Array), or a combination thereof.

[0149] The control circuit 101 controls the operation of the CPU unit 20 by executing various programs such as a control program 122. The control program 122 is a program for implementing various processes described in this specification. Based on receiving an execution command for the control program 122, the control circuit 101 reads the control program 122 from the auxiliary storage device 120 or the ROM 102 to the RAM 103. The RAM 103 functions as a working memory and temporarily stores various data required for the execution of the control program 122.

[0150] The communication interface 104 is an interface for performing periodic communication with external devices using a field network. The external devices include, for example, the above-mentioned motor driver 54, the above-mentioned pump 56, the above-mentioned orifice valves 58A and 58B, the pressure sensor 59, and the flow rate sensor 60. As the field network, for example, PROFINET (registered trademark), EtherCAT (registered trademark), EtherNet / IP (registered trademark), CC-Link (registered trademark), CompoNet (registered trademark), or the like is adopted.

[0151] A LAN (Local Area Network), an antenna, etc. are connected to the communication interface 105. The CPU unit 20 is connected to a network via the communication interface 105. Thereby, the CPU unit 20 exchanges data with external devices connected to the network. The external devices include, for example, the above-described operation panel 400 and a server (not shown).

[0152] The auxiliary storage device 120 is a storage medium such as a hard disk or a flash memory, for example. The auxiliary storage device 120 stores a control program 122 and the like. Note that the storage location of the control program 122 is not limited to the auxiliary storage device 120, and it may be stored in a storage area of the control circuit 101 (for example, a cache memory), the ROM 102, the RAM 103, an external device (for example, a server), or the like.

[0153] Further, the control program 122 may be provided not as a single program but incorporated into a part of an arbitrary program. In this case, various processes according to the present embodiment are realized in cooperation with an arbitrary program. Even a program that does not include such a part of the module does not deviate from the gist of the control program 122 according to the present embodiment. Furthermore, part or all of the functions provided by the control program 122 may be realized by dedicated hardware. Furthermore, the control unit 50 may be configured in a form such as a so-called cloud service in which at least one server executes a part of the processing of the control program 122.

[0154] <Hardware Configuration of G.CNC Unit 30> Next, with reference to FIG. 14, the hardware configuration of the CNC unit 30, which is an example of the above-described control unit 50, will be described. FIG. 14 is a diagram showing an example of the hardware configuration of the CNC unit 30.

[0155] The CNC unit 30 includes a control circuit 301, a ROM 302, a RAM 303, a communication interface 304, and an auxiliary storage device 320. These components are connected to an internal bus 309.

[0156] The control circuit 301 is configured, for example, by at least one integrated circuit. The integrated circuit may be configured, for example, by at least one CPU, at least one GPU, at least one ASIC, at least one FPGA, or a combination thereof.

[0157] The control circuit 301 controls the operation of the CNC unit 30 by executing various programs such as a workpiece machining program 322. Upon receiving an execution command for the machining program 322, the control circuit 301 reads the machining program 322 from the ROM 302 to the RAM 303. The RAM 303 functions as a working memory and temporarily stores various data required for executing the machining program 322.

[0158] The communication interface 304 is an interface for performing periodic communication with external devices using a field network. The external devices include, for example, the CPU unit 20. As the field network, for example, EtherCAT, EtherNet / IP, CC-Link, CompoNet, or the like is adopted.

[0159] The auxiliary storage device 320 is a storage medium such as a hard disk or a flash memory. The auxiliary storage device 320 stores a machining program 322 and the like. The storage location of the machining program 322 is not limited to the auxiliary storage device 320, and may be stored in a memory area (e.g., cache memory) of the control circuit 301, the ROM 302, the RAM 303, an external device (e.g., a server), or the like.

[0160] Further, the machining program 322 may be provided not as a single program but incorporated into a part of any program. In this case, the control process defined in the machining program 322 is realized in cooperation with any program. Even a program that does not include such a partial module does not deviate from the gist of the machining program 322 according to the present embodiment. Furthermore, some or all of the functions provided by the machining program 322 may be realized by dedicated hardware. Further, the machine tool 100 may be configured in a form such as a so-called cloud service in which at least one server executes a part of the processing of the machining program 322.

[0161] <H. Hardware Configuration of the Operation Panel 400> Next, with reference to FIG. 15, the hardware configuration of the operation panel 400, which is an example of the above-described control unit 50, will be described. FIG. 15 is a diagram showing an example of the hardware configuration of the operation panel 400.

[0162] The operation panel 400 includes a control circuit 401, a ROM 402, a RAM 403, a communication interface 404, a display 405, operation keys 406, and an auxiliary storage device 420. These components are connected to an internal bus 409.

[0163] The control circuit 401 is constituted by, for example, at least one integrated circuit. The integrated circuit can be constituted by, for example, at least one CPU, at least one GPU, at least one ASIC, at least one FPGA, or a combination thereof.

[0164] The control circuit 401 controls the operation of the operation panel 400 by executing various programs such as a control program 422. The control program 422 is a program for realizing various processes described in this specification. Based on receiving an execution command for the control program 422, the control circuit 401 reads the control program 422 from the auxiliary storage device 420 or the ROM 402 to the RAM 403. The RAM 403 functions as a working memory and temporarily stores various data required for the execution of the control program 422.

[0165] A LAN, an antenna, etc. are connected to the communication interface 404. The operation panel 400 is connected to a network via the communication interface 404. As a result, the operation panel 400 exchanges data with external devices connected to the network. The external devices include, for example, the above-mentioned CPU unit 20 and a server (not shown).

[0166] Display 405 is, for example, a liquid crystal display, an organic EL display, or other display device. Display 405 sends image signals for displaying images to display 405 in accordance with instructions from control circuit 401 or the like. Display 405 is, for example, configured with a touch panel, and accepts various operations for machine tool 100 by touch operations.

[0167] The operation keys 406 are composed of a plurality of hardware keys, and accept various user operations on the operation panel 400. A signal corresponding to a pressed key is output to the control circuit 401.

[0168] The auxiliary storage device 420 is, for example, a storage medium such as a hard disk or a flash memory. The auxiliary storage device 420 stores a control program 422 and the like. The storage location of the control program 422 is not limited to the auxiliary storage device 420, and may be stored in a storage area (for example, a cache memory) of the control circuit 401, the ROM 402, the RAM 403, an external device (for example, a server), or the like.

[0169] Further, the control program 422 may be provided not as a single program but incorporated into a part of any program. In this case, various processes according to the present embodiment are realized in cooperation with any program. Even a program that does not include such a part of the module does not deviate from the gist of the control program 422 according to the present embodiment. Furthermore, part or all of the functions provided by the control program 422 may be realized by dedicated hardware. Furthermore, the control unit 50 may be configured in a form such as a so-called cloud service in which at least one server executes a part of the processing of the control program 422.

[0170] <I. Implementation Forms> The calibration program for realizing various processes related to the above-described calibration phase may be implemented in the above-described CPU unit 20, may be implemented in the above-described operation panel 400, or may be implemented in other computers.

[0171] Similarly, the discharge program for realizing the discharge of the coolant in the above-described processing phase may be implemented in the above-described CPU unit 20, may be implemented in the above-described operation panel 400, or may be implemented in other computers.

[0172] Hereinafter, with reference to FIG. 16, an example of an implementation form of the calibration program PR1 and the discharge program PR2 will be described. FIG. 16 is a diagram showing an example of an implementation form of the calibration program PR1 and the discharge program PR2.

[0173] In the example of FIG. 16, the control unit 50 is composed of the above-described CPU unit 20 (first control device) and the above-described operation panel 400 (second control device).

[0174] In this example, the calibration program PR1 is included in the above-described control program 422 (see FIG. 13). In this case, the operation panel 400 is responsible for various controls in the above-described calibration phase. Accordingly, various information referred to by the calibration program PR1 is stored in the operation panel 400. Such information includes the above-described correlation information 124 and the above-described tool database 126.

[0175] In this example, the discharge program PR2 is included in the above-described control program 122 (see FIG. 13). In this case, the CPU unit 20 is responsible for the coolant discharge control in the above-described machining phase. Accordingly, various information referred to by the discharge program PR2 is stored in the CPU unit 20. Such information includes the above-described threshold value information 128.

[0176] Note that the calibration program PR1 may be executed on a computer different from the operation panel 400. As an example, the calibration program PR1 may be implemented in a magazine server (not shown) that stores information regarding the above-described magazine 150. The magazine server is configured to be communicable with the operation panel 400. Also, various information referred to by the calibration program PR1 is stored in the magazine server. Such information includes the above-described correlation information 124 and the above-described tool database 126.

[0177] <J. Modified Example> Next, with reference to FIG. 17, a modified example of the coolant supply mechanism shown in FIG. 2 will be described. FIG. 17 is a diagram showing a coolant supply mechanism according to the modified example.

[0178] The coolant supply mechanism according to this modified example further includes a branch flow path F3, a draw-back valve 58C, and a pressure holding valve 58D, and is different from the coolant supply mechanism shown in FIG. 2. Since the other points are as described above, the description thereof will not be repeated.

[0179] The branch flow path F3 branches off from the main flow path F1 at a branch point P3. The branch point P3 is located, for example, downstream of the pump 56 and upstream of the pressure maintaining valve 58D.

[0180] More specifically, one end of the branch flow path F3 is connected to the main flow path F1. The other end of the branch flow path F3 may be connected to any other destination. In the example of Fig. 17, the other end of the branch flow path F3 is connected to the coolant tank 52. As another example, the other end of the branch flow path F3 may be connected to a coolant tank other than the coolant tank 52.

[0181] The drawback valve 58C is provided, for example, in the branch flow path F3. As an example, the drawback valve 58C is configured to be switchable between at least two states, an open state and a closed state, in response to a control command from the control unit 50. The opening degree of the drawback valve 58C may be adjustable or may be constant.

[0182] When the drawback valve 58C is closed, the flow of coolant through the branch passage F3 is stopped. On the other hand, when the drawback valve 58C is open, the coolant can flow through the branch passage F3.

[0183] Typically, the drawback valve 58C is provided upstream of the pressure-retaining valve 58D. In other words, the length of the coolant flow passage between the pressure-retaining valve 58D and the spindle 180 is shorter than the length of the coolant flow passage between the drawback valve 58C and the spindle 180.

[0184] The pressure maintaining valve 58D is provided in the main flow path F1. The pressure maintaining valve 58D is provided downstream of the pump 56 and upstream of the main shaft 180, for example.

[0185] The pressure maintaining valve 58D is configured to be switchable between at least two states, an open state and a closed state, in response to a control command from the control unit 50. The opening degree of the pressure maintaining valve 58D may be adjustable or may be constant.

[0186] When the pressure-maintaining valve 58D is in a closed state, the flow of coolant from the coolant tank 52 to the spindle 180 is stopped. On the other hand, when the pressure-maintaining valve 58D is in an open state, the coolant flows from the coolant tank 52 to the spindle 180. In this case, the coolant pumped by the pump 56 flows through the main flow path F1, the communication path L2, and the through path L1 in this order, and is discharged from the tip of the machining tool T to the workpiece to be machined.

[0187] Next, a description will be given of the drawback process using the drawback valve 58C and the pressure maintaining valve 58D.

[0188] It is assumed that the control unit 50 receives a command to replace the machining tool T. In response to this, the control unit 50 stops driving the pump 56 and executes a drawback process.

[0189] More specifically, the control unit 50 switches the drawback valve 58C from a closed state to an open state. The control unit 50 also opens the pressure-maintaining valve 58D and closes the orifice valve 58B. This causes at least the amount of coolant from the pressure-maintaining valve 58D to the opening on the tip side of the machining tool T to be returned to the branch flow path F3. Typically, the coolant remaining in the communication passage L2, the through passage L1, and the main flow path F1 is discharged from the branch flow path F3. This makes it possible to prevent the coolant from dripping from the machining tool T or the spindle 180 when replacing the machining tool T.

[0190] Preferably, a suction mechanism such as an ejector (not shown) may be provided at the branch point P3 or the branch flow path F3. The ejector generates negative pressure in the branch flow path F3 during the drawback process. This allows the coolant to flow efficiently from the main flow path F1 to the branch flow path F3.

[0191] Preferably, the coolant returned from the main flow path F1 to the branch flow path F3 is sent back to the main flow path F1. At this time, the coolant returned to the branch flow path F3 is sent to the main flow path F1 via one or more coolant tanks 52. As an example, the coolant is discharged from the branch flow path F3 to the coolant tank 52. Then, the coolant discharged to the coolant tank 52 is sucked up by the pump 56 and sent back to the main flow path F1. This reduces the consumption of coolant.

[0192] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0193] 20 CPU unit, 30 CNC unit, 40A tool storage unit, 40B processing machine body, 50 control unit, 52 coolant tank, 54 motor driver, 55 motor, 56 pump, 58 adjustment mechanism, 58A orifice valve, 58B orifice valve, 58C drawback valve, 58D pressure retention valve, 59 pressure sensor, 60 flow sensor, 100 machine tool, 101 control circuit, 102 ROM, 103 RAM, 104 communication interface, 105 communication interface, 109 internal bus, 120 auxiliary storage device, 122 control program, 124 correlation information, 125A discharge pressure, 125B discharge amount, 125C opening size, 126 tool database, 128 threshold information, 150 magazine, 170 spindle head, 175 spindle tube, 180 spindle, 301 Control circuit, 302 ROM, 303 RAM, 304 communication interface, 309 internal bus, 320 auxiliary storage device, 322 machining program, 400 operation panel, 401 control circuit, 402 ROM, 403 RAM, 404 communication interface, 405 display, 406 operation key, 409 internal bus, 420 auxiliary storage device, 422 control program, D door, F1 main flow path, F2 branch flow path, F2A branch flow path, F2B branch flow path, F3 branch flow path, FRA orifice, FRB orifice, L1 through passage, L2 communication passage, P2A branch point, P2B branch point, P3 branch point, PR1 calibration program, PR2 discharge program, T machining tool, T0 timing, T1 timing, W workpiece.

Claims

1. A machine tool capable of machining a workpiece using a machining tool having a first coolant passage formed therein, a spindle configured to be able to mount the machining tool and having a second passage that is connected to the first passage when the machining tool is mounted; a pump for pumping coolant to a main passage connected to the second passage; an adjusting mechanism capable of adjusting a flow rate of the coolant in one or more branch passages branched from the main passage or in the main passage; a pressure sensor for detecting a discharge pressure of the coolant from the machining tool; a flow rate sensor for detecting an amount of coolant discharged from the machining tool; A control unit. The control unit is Executing a process to acquire information defining a relationship between a discharge pressure of a coolant from an outlet of a machining tool, a discharge amount of the coolant from the outlet, and a characteristic value correlating with a flow resistance of the coolant in the machining tool, the characteristic value being a characteristic value related to the machining tool; The control unit further includes: A machine tool that executes a process of estimating the characteristic value for the machining tool attached to the spindle based on the information, the discharge pressure detected by the pressure sensor, and the discharge rate detected by the flow rate sensor.

2. the characteristic value related to the machining tool defined in the information is a size of a discharge port of the machining tool; The machine tool according to claim 1 , wherein the characteristic value related to the machining tool estimated in the estimating process is a size of a discharge port of the machining tool.

3. The control unit further includes: controlling the adjustment mechanism in response to the estimated size; The machine tool according to claim 2 , further comprising a step of controlling the pump, after the step of controlling is performed.

4. The branch flow paths from the main flow path include a first branch flow path and a second branch flow path, The adjustment mechanism includes: a first valve provided in the first branch flow path; a second valve provided in the second branch flow path, The first valve is configured to at least switch whether or not the coolant in the main flow path is caused to flow into the first branch flow path by opening and closing the first valve, The second valve is configured to at least switch whether or not the coolant in the main flow path is caused to flow into the second branch flow path by opening and closing the second valve, The machine tool according to claim 3 , wherein the process of controlling the adjustment mechanism controls opening and closing of the first valve and opening and closing of the second valve.

5. a maximum flow rate of the coolant in the first branch passage when the first valve is opened is less than a maximum flow rate of the coolant in the second branch passage when the second valve is opened; In the process of controlling the adjustment mechanism, if the estimated size is less than a first threshold, the first valve is closed and the second valve is opened; if the estimated size is greater than or equal to the first threshold and less than a second threshold, the first valve is opened and the second valve is closed; if the estimated size is greater than or equal to the second threshold, both the first valve and the second valve are closed; The machine tool according to claim 4 , wherein the first threshold value is smaller than the second threshold value.

6. The process of controlling the pump includes: a feedforward control for controlling the pump without being based on a discharge pressure detected by the pressure sensor and a discharge amount detected by the flow rate sensor; a feedback control for controlling the pump so that the discharge pressure detected by the pressure sensor or the discharge amount detected by the flow rate sensor approaches a target value; In the process of controlling the pump, When the target value is smaller than a predetermined threshold value, execution of the feedback control is started after execution of the feedforward control, The machine tool according to any one of claims 3 to 5, wherein, when the target value is equal to or greater than the predetermined threshold value, the feedforward control is not executed and execution of the feedback control is started.

7. The control unit is A first control device capable of controlling the pump; a second control device different from the first control device, The machine tool according to any one of claims 1 to 5, wherein the estimating process is executed by the second control device.

8. A method for controlling a machine tool capable of machining a workpiece using a machining tool having a first coolant passage formed therein, comprising the steps of: The machine tool comprises: a spindle configured to be able to mount the machining tool and having a second passage that is connected to the first passage when the machining tool is mounted; a pump for pumping coolant to a main passage connected to the second passage; an adjusting mechanism capable of adjusting a flow rate of the coolant in one or more branch passages branched from the main passage or in the main passage; a pressure sensor for detecting a discharge pressure of the coolant from the machining tool; a flow rate sensor for detecting an amount of coolant discharged from the machining tool; The control method includes: a step of acquiring information defining a relationship between a discharge pressure of the coolant from an outlet of the machining tool, a discharge amount of the coolant from the outlet, and a characteristic value correlating with a flow resistance of the coolant in the machining tool, the characteristic value being a characteristic value related to the machining tool; The control method further comprises: a step of estimating the characteristic value for the machining tool attached to the spindle based on the information, the discharge pressure detected by the pressure sensor, and the discharge rate detected by the flow rate sensor.

9. A control program for a machine tool capable of machining a workpiece using a machining tool having a first coolant passage formed therein, comprising: The machine tool comprises: a spindle configured to be able to mount the machining tool and having a second passage that is connected to the first passage when the machining tool is mounted; a pump for pumping coolant to a main passage connected to the second passage; an adjusting mechanism capable of adjusting a flow rate of the coolant in one or more branch passages branched from the main passage or in the main passage; a pressure sensor for detecting a discharge pressure of the coolant from the machining tool; a flow rate sensor for detecting an amount of coolant discharged from the machining tool; The control program causes the machine tool to execute a process for acquiring information defining a relationship between a discharge pressure of a coolant from an outlet of a machining tool, a discharge amount of the coolant from the outlet, and a characteristic value correlating with a flow resistance of the coolant in the machining tool, the characteristic value being a characteristic value related to the machining tool; The control program further causes the machine tool to a control program that executes a process of estimating the characteristic value for the machining tool attached to the spindle based on the information, the discharge pressure detected by the pressure sensor, and the discharge amount detected by the flow rate sensor.

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