Patent Publication Number: US-2023144591-A1

Title: Machine tool, machine tool control method, and non-transitory computer-readable medium

Description:
TECHNICAL FIELD 
     The present disclosure relates to a technique for controlling discharge of a coolant in a machine tool. 
     BACKGROUND ART 
     Regarding a technique for removing chip generated by machining of a workpiece with a coolant, Japanese Patent Laying-Open No. 2017-94420 (PTL 1) discloses a machine tool for “detect a place where the chip generated by machining adheres and accumulates inside the cover, and efficiently discharge the chip”. 
     As another example, Japanese Patent Laying-Open No. 2000-52185 (PTL 2) discloses a machine tool cleaning device “capable of cleaning the chip and the like that affect tool replacement”. 
     Citation List 
     Patent Literature 
     PTL 1: Japanese Patent Laying-Open No. 2017-94420 
     PTL 2: Japanese Patent Laying-Open No. 2000-52185 
     SUMMARY OF INVENTION 
     Technical Problem 
     In the machine tool, there is a portion (hereinafter, also referred to as a “discharge inhibited portion”) that may fail due to the adhesion of the coolant. Desirably the coolant is prevented from adhering to such the discharge inhibited portion. 
     The techniques disclosed in PTLs 1, 2 do not prevent the coolant from adhering to the discharge inhibited portion. Accordingly, a technique for preventing the coolant from adhering to the discharge inhibited portion is desired. 
     Solution to Problem 
     In an example of the present disclosure, a machine tool capable of machining a workpiece includes: a first discharge unit that discharges a coolant removing a chip of the workpiece; a portion inside the machine tool and to which the coolant should not be discharged; a first drive unit that changes a relative position between the first discharge unit and the portion by moving at least one of the first discharge unit and the portion; and a control unit that controls the machine tool. The control unit performs processing for recognizing a position in the machine tool of a moving object by the first drive unit between the first discharge unit and the portion, and processing for controlling the discharge of the coolant by the first discharge unit such that the coolant is not discharged to the portion based on the position recognized in the recognition processing. 
     According to an example of the present disclosure, the machine tool further includes a second drive unit that drives a discharge port of the coolant discharged by the first discharge unit. The moving object is the portion. In the control processing, drive of the discharge port by the second drive unit is controlled such that the coolant is not discharged to the position of the portion. 
     In an example of the present disclosure, the machine tool further includes a second discharge unit that discharges the coolant removing the chip of the workpiece. The control processing includes processing for controlling the discharge of the coolant by the first discharge unit and the discharge of the coolant by the second discharge unit such that the coolant is not discharged to the portion. 
     In an example of the present disclosure, the machine tool further includes a camera that photographs the portion. A position of the portion in the machine tool is recognized based on an image obtained from the camera. 
     In an example of the present disclosure, the position of the portion in the machine tool is recognized by analyzing a drive program of the portion by the second drive unit. 
     In an example of the present disclosure, the control unit further executes processing for recognizing a position of the chip of the workpiece. The control processing includes processing for causing the first drive unit to move the relative position such that the portion is not located between the first discharge unit and the chip when the portion is located between the first discharge unit and the chip, and starting the discharge of the coolant by the first discharge unit after the movement. 
     In an example of the present disclosure, the portion includes at least one of a sensor measuring a size of a tool for machining the workpiece, a sensor measuring a physical quantity related to the workpiece, a camera provided in the machine tool, a surface of a spindle provided in the machine tool, and a workpiece to be machined by dry machining. 
     An example of the present disclosure provides a method for controlling a machine tool capable of machining a workpiece. The machine tool includes a discharge unit that discharges a coolant removing a chip of the workpiece, a portion inside the machine tool and to which the coolant should not be discharged, and a drive unit that changes a relative position between the discharge unit and the portion by moving at least one of the discharge unit and the portion. The control method includes: recognizing a position in the machine tool of a moving object by the drive unit between the discharge unit and the portion; and controlling discharge of the coolant by the discharge unit such that the coolant is not discharged to the portion based on the position recognized by the recognizing. 
     An example of the present disclosure provides a control program for a machine tool capable of machining a workpiece. The machine tool includes a discharge unit that discharges a coolant removing a chip of the workpiece, a portion inside the machine tool and to which the coolant should not be discharged, and a drive unit that changes a relative position between the discharge unit and the portion by moving at least one of the discharge unit and the portion. The control program causes the machine tool to execute: recognizing a position in the machine tool of a moving object by the drive unit between the discharge unit and the portion; and controlling the discharge of the coolant by the discharge unit such that the coolant is not discharged to the portion based on the position recognized in the recognizing. 
     The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a view illustrating an appearance of a machine tool. 
         FIG.  2    is a view illustrating a state in the machine tool. 
         FIG.  3    is a view illustrating the state in the machine tool from a direction different from that in  FIG.  2   . 
         FIG.  4    is a view illustrating a configuration example of a drive mechanism in the machine tool. 
         FIG.  5    is a view illustrating an example of a functional configuration of the machine tool. 
         FIG.  6    is a view illustrating an image obtained from a camera. 
         FIG.  7    is a view illustrating a chip region recognized from the image in  FIG.  6   . 
         FIG.  8    is a view illustrating a cleaning path by a discharge mechanism. 
         FIG.  9    is a view illustrating a positional relationship among the discharge mechanism, a discharge inhibited portion, and a chip of a workpiece. 
         FIG.  10    is a view illustrating the positional relationship among the discharge mechanism, the discharge inhibited portion, and the chip of the workpiece. 
         FIG.  11    is a view illustrating an example of a hardware configuration of a controller. 
         FIG.  12    is a flowchart illustrating an example of coolant control. 
     
    
    
     DESCRIPTION OF EMBODIMENT 
     With reference to the drawings, an embodiment of the present invention will be described below. In the following description, the same parts and components are denoted by the same reference numeral. Those names and functions are the same. Thus, the detailed description thereof will not be repeated. The following embodiments and modifications described below may selectively be combined as appropriate. 
     A. Appearance of Machine Tool  100   
     With reference to  FIG.  1   , a machine tool  100  according to an embodiment will be described.  FIG.  1    is a view illustrating an appearance of machine tool  100 . 
     The term “machine tool” used in the present specification is a concept including various devices having a function of processing a workpiece. In the present specification, a horizontal machining center will be described as an example of machine tool  100 , but machine tool  100  is not limited thereto. For example, machine tool  100  may be a vertical machining center. Alternatively, machine tool  100  may be a lathe, an additional processing machine, or another cutting machine or grinding machine. 
     As illustrated in  FIG.  1   , machine tool  100  includes a cover  130  and an operation panel  140 . 
     Cover  130  is also called a splash guard, and forms an appearance of machine tool  100  and defines a machining area AR (see  FIG.  2   ) of a workpiece W. 
     Operation panel  140  is a general-purpose computer, and includes a display  142  displaying various types of information about processing. For example, display  142  is a liquid crystal display, an organic electro luminescence (EL) display, or another display device. Display  142  includes a touch panel, and receives various operations on machine tool  100  by touch operations. 
     B. Internal Configuration of Machine Tool  100   
     With reference to  FIGS.  2  and  3   , an internal configuration of machine tool  100  will be described below.  FIG.  2    is a view illustrating a state in machine tool  100 .  FIG.  3    is a view illustrating the state in machine tool  100  from a direction different from that in  FIG.  2   . 
     As illustrated in  FIGS.  2  and  3   , machine tool  100  includes cameras  120 A,  120 B, coolant discharge mechanisms  125 A,  125 B (first and second discharge units), a chip collection mechanism  127 , a spindle head  131 , a tool  134 , and a table  136 . Spindle head  131  includes a spindle  132  and a housing  133 . 
     For convenience of description, hereinafter, the axial direction of spindle  132  is also referred to as a “Z-axis direction”. A gravity direction is also referred to as a “Y-axis direction”. A direction orthogonal to both the Y-axis direction and the Z-axis direction is referred to as an “X-axis direction”. 
     Furthermore, in the following description, when cameras  120 A,  120 B are not particularly distinguished, one of cameras  120 A,  120 B is also referred to as a camera  120 . When discharge mechanisms  125 A,  125 B are not particularly distinguished, one of discharge mechanisms  125 A,  125 B is also referred to as a discharge mechanism  125 . 
     Camera  120  is disposed so as to include a machining area AR of the workpiece in a field of view of camera  120 . For example, camera  120  is provided on one side surface or a ceiling surface of cover  130 . Camera  120  may be a charge coupled device (CCD) camera, an infrared camera (thermography), or another types of camera. 
     Discharge mechanism  125  is provided in machine tool  100 . For example, discharge mechanism  125  is provided on one side surface or the ceiling surface of cover  130 . Discharge mechanism  125  includes a coolant storage tank, piping, a coolant pump, a coolant nozzle (discharge port), and the like. One end of the pipe is connected to the pump, and the other end of the pipe is connected to the coolant nozzle. The pump draws the coolant from the storage tank and sends the coolant to the coolant nozzle. Thus, the coolant is discharged to machining area AR. By discharging the coolant, the chip generated by machining of workpiece W is collected by collection mechanism  127 . Collection mechanism  127  includes a conveyor, a collection unit, and the like, and conveys the chip of workpiece W to the collection unit by the conveyor. 
     Spindle  132  is provided inside housing  133 . A tool for machining workpiece W, which is an object to be machined, is attached to spindle  132 . In the examples of  FIGS.  2  and  3   , a tool  134  used for milling workpiece W is mounted on spindle  132 . 
     Although the example in which two cameras  120 A,  120 B are provided in machine tool  100  has been described above, the number of cameras is not necessarily two, but may be one or at least three. 
     In the above description, an example in which two discharge mechanisms  125 A,  125 B are provided in machine tool  100  has been described. However, the number of discharge mechanisms is not necessarily two, and may be one or at least three. 
     C. Discharge Inhibited Portion 
     The definition of the term “discharge inhibited portion” used in the present specification will be described below. In the present specification, a portion that may fail due to the adhesion of the coolant is referred to as the “discharge inhibited portion”. The discharge inhibited portion may be one component in machine tool  100  or a part of the one component. 
     As an example, the discharge inhibited portion is a sensor (hereinafter, also referred to as a “tool sensor”) measuring a size of the tool used for machining workpiece W. The size is a concept including a diameter of the tool, a length of the tool, a wear amount of the tool, and the like. For example, the tool sensor is provided in machine tool  100  and measures the size of the tool before or after machining the workpiece. For example, the tool sensor is an optical distance sensor, an ultrasonic distance sensor, and a contact measurement device that measures the size of the tool. 
     As another example, the discharge inhibited portion is a sensor (hereinafter, also referred to as a “workpiece sensor”) measuring a physical quantity related to the workpiece. The physical quantity is a concept including a height of the workpiece, a lateral width of the workpiece, a longitudinal width of the workpiece, roughness of the workpiece surface, a temperature of the workpiece, and the like. For example, the workpiece sensor is provided in machine tool  100 , and measures physical quantities of the workpiece before machining, the workpiece being machined, and the workpiece after machining. For example, the workpiece sensor is an optical distance sensor, an ultrasonic distance sensor, a contact measurement device that measures the size of the workpiece, or a temperature sensor such as thermography. 
     As another example, the discharge inhibited portion is a camera provided in machine tool  100 . Not only cameras  120 A,  120 B but also various cameras are provided in machine tool  100 . As an example, the camera includes a camera monitoring the machining of workpiece W, a camera monitoring the state of the tool, a camera detecting the chip of the workpiece W, and the like. 
     As another example, the discharge inhibited portion includes the surface of the spindle  132  extending in the axial direction (that is, in the Z-axis direction) of spindle  132 . When the coolant enters between spindle  132  and housing  133 , there is a possibility that spindle head  131  fails. In order to prevent this, a labyrinth structure is adopted for a connection portion between spindle  132  and housing  133 . In order to more reliably prevent the coolant from entering between spindle  132  and housing  133 , preferably the coolant is not attached to the surface portion of spindle  132  corresponding to the labyrinth structure. For this reason, the surface portion of spindle  132  corresponding to the labyrinth structure is an example of the discharge inhibited portion. 
     As another example, the discharge inhibited portion includes the workpiece to be machined by dry machining. The dry machining is a type of machining method in which the coolant is not attached to the workpiece. Preferably the coolant does not adhere to the workpiece used in such the dry processing. For this reason, the workpiece used in the dry machining is an example of the discharge inhibited portion. For example, whether the machining method is the dry machining is determined based on an instruction code defined in a machining program. 
     In the following description, the surface of spindle  132  will be described as an example of the discharge inhibited portion. However, the discharge inhibited portion is not limited to the surface of spindle  132 , but may be another example described above. 
     D. Drive Mechanism of Machine Tool  100   
     With reference to  FIG.  4   , various drive mechanisms in machine tool  100  will be described below.  FIG.  4    is a view illustrating a configuration example of a drive mechanism in machine tool  100 . 
     As illustrated in  FIG.  4   , machine tool  100  includes a controller  50 , motor drivers  111 A,  111 B, servo drivers  111 R,  111 X to  111 Z, stepping motors  112 A 1 , 112 A 2 , 112 B 1 , 112 B 2 , servomotors  112 R,  112 X to  112 Z, a moving body  113 , discharge mechanisms  125 A,  125 B, spindle head  131 , tool  134 , and table  136 . 
     “Controller  50 ” used in the present specification means a device that controls machine tool  100 . The device configuration of controller  50  is arbitrary. Controller  50  may be constructed with a single control unit or a plurality of control units. In the example of  FIG.  4   , controller  50  includes a CPU unit  20  as a programmable logic control unit (PLC) and a CNC unit  30 . CPU unit  20  and CNC unit  30  communicate with each other through a communication path B (for example, a fieldbus or a LAN cable). 
     CPU unit  20  controls various units constituting controller  50  according to a previously-designed PLC program. For example, the PLC program is described by a ladder program. CPU unit  20  controls motor driver  111 A according to the PLC program, and controls the discharge of the coolant by discharge mechanism  125 A and the rotational drive of discharge mechanism  125 A. CPU unit  20  controls motor driver  111 B according to the PLC program, and controls the discharge of the coolant by discharge mechanism  125 B and the rotational drive of discharge mechanism  125 B. 
     CNC unit  30  starts execution of a previously-designed machining program in response to reception of a machining start instruction from CPU unit  20 . For example, the machining program is described by a numerical control (NC) program. CNC unit  30  controls servo drivers  111 R,  111 X to  111 Z according to the machining program to machine workpiece W fixed to table  136 . 
     In the example of  FIG.  4   , motor driver  111 A is illustrated as a two-shaft integrated driver. Motor driver  111 A receives the input of the target rotation speed of stepping motor  112 A 1  and the input of the target rotation speed of stepping motor  112 A 2  from CPU unit  20 , and controls each of stepping motors  112 A 1 ,  112 A 2 . 
     Stepping motor  112 A 1  rotationally drives a discharge port of the coolant by discharge mechanism  125 A according to an output current from motor driver  111 A, and changes a discharge direction of the coolant in a rotation direction (that is, in an A-axis direction) with the X-axis direction as a rotation axis. 
     Stepping motor  112 A 2  rotationally drives the discharge port of the coolant by discharge mechanism  125 A according to the output current from motor driver  111 A, and changes the discharge direction of the coolant in the rotation direction (that is, in a C-axis direction) with the Z-axis direction as the rotation axis. 
     As described above, motor driver  111 A individually controls the rotational drive in the A-axis direction by stepping motor  112 A 1  and the rotational drive in the C-axis direction by stepping motor  112 A 2 , thereby discharging the coolant in an arbitrary direction toward machining area AR. 
     Motor driver  111 B is a biaxial integrated driver. Motor driver  111 B receives the input of the target rotation speed of stepping motor  112 B 1  and the input of the target rotation speed of stepping motor  112 B 2  from CNC unit  30 , and controls each of stepping motors  112 B 1 ,  112 B 2 . Because a method of controlling stepping motor  112 B 1 ,  112 B 2  by motor driver  111 B is similar to that of motor driver  111 A, the description thereof will not be repeated. 
     Servo driver  111 R sequentially receives the input of the target rotation speed from CNC unit  30  and controls servomotor  112 R. Servomotor  112 R rotationally drives spindle  132  about the Z-axis direction. 
     More specifically, servo driver  111 R calculates an actual rotation speed of servomotor  112 R from a feedback signal of an encoder (not illustrated) detecting the rotation angle of servomotor  112 R, increases the rotation speed of servomotor  112 R when the actual rotation speed is smaller than the target rotation speed, and decreases the rotation speed of servomotor  112 R when the actual rotation speed is larger than the target rotation speed. In this manner, servo driver  111 R brings the rotation speed of servomotor  112 R closer to the target rotation speed while sequentially receiving feedback of the rotation speed of servomotor  112 R. 
     Servo driver  111 X sequentially receives an input of a target position from CNC unit  30  and controls servomotor  112 X. Servomotor  112 X feeds and drives moving body  113  to which spindle head  131  is attached through a ball screw (not illustrated), and moves spindle  132  to an arbitrary position in the X-direction. Because a method for controlling servomotor  112 X by servo driver  111 X is similar to that of servo driver  111 R, the description thereof will not be repeated. 
     Servo driver  111 Y sequentially receives the input of the target position from CNC unit  30  and controls servomotor  112 Y. Servomotor  112 Y feeds and drives moving body  113  to which spindle head  131  is attached through a ball screw (not illustrated), and moves spindle  132  to an arbitrary position in the Y-direction. Because a method for controlling servomotor  112 Y by servo driver  111 Y is similar to that of servo driver  111 R, the description thereof will not be repeated. 
     Servo driver  111 Z sequentially receives the input of the target position from CNC unit  30  and controls servomotor  112 Z. Servomotor  112 Z feeds and drives moving body  113  to which spindle head  131  is attached through a ball screw (not illustrated), and moves spindle  132  to an arbitrary position in the Z-direction. Because a method of controlling servomotor  112 Z by servo driver  111 Z is similar to that of servo driver  111 R, the description thereof will not be repeated. 
     In the above description, servomotors  112 X to  112 Z that drive the discharge inhibited portion are exemplified as the drive mechanism (hereinafter, also referred to as a “first drive unit”) that changes the relative position between the discharge inhibited portion (in the above-described example, spindle  132 ) and discharge mechanism  125 , but the drive target by the first drive unit is not limited to the discharge inhibited portion. As an example, the first drive unit may change the relative position by feeding and driving discharge mechanism  125  instead of the discharge inhibited portion, or may change the relative position by feeding and driving both the discharge inhibited portion and discharge mechanism  125 . When discharge mechanism  125  is fed and driven, in addition to stepping motor  112 A 1 ,  112 A 2 ,  112 B 1 ,  112 B 2  (hereinafter, also referred to as a “second drive unit”) rotationally driving discharge mechanism  125 , or instead of the second drive unit, a servomotor (not illustrated) feeding and driving discharge mechanism  125  is provided in machine tool  100  as the first drive unit. In this case, for example, discharge mechanism  125  is driven along a rail (not illustrated) provided on the ceiling of machine tool  100 . 
     Furthermore, in the above description, the example in which the first drive unit is configured by three servomotors  112 X to  112 Z has been described. However, the first drive unit may be configured by at least one drive mechanism (for example, a servomotor) feeding and driving the discharge inhibited portion or discharge mechanism  125 . 
     Furthermore, in the above description, an example in which the second drive unit is configured by two stepping motors  112 A 1 ,  112 A 2  (or  112 B 1 ,  112 B 2 ) has been described. However, the second drive unit may be configured by at least one drive mechanism (for example, a stepping motor or a servo motor). 
     E. Functional Configuration of Machine Tool  100   
     With reference to  FIGS.  5  to  10   , a functional configuration of machine tool  100  will be described below.  FIG.  5    is a view illustrating an example of the functional configuration of machine tool  100 . 
     Machine tool  100  includes controller  50  and a storage device  160  as a main hardware configuration. Controller  50  includes a position recognition unit  152 , a chip recognition unit  154 , and a coolant control unit  156  as a functional configuration. These functional configurations may be implemented in CPU unit  20  (see  FIG.  4   ) or implemented in CNC unit  30  (see  FIG.  4   ). 
     The functional configurations of position recognition unit  152 , chip recognition unit  154 , and coolant control unit  156  will be sequentially described below. 
     E1. Position Recognition Unit  152   
     With reference to  FIG.  6   , the function of position recognition unit  152  will be described. 
     Position recognition unit  152  recognizes the position in machine tool  100  of the moving object between discharge mechanism  125  and the discharge inhibited portion. Hereinafter, an example in which position recognition unit  152  recognizes the position of the discharge inhibited portion will be described, but when discharge mechanism  125  is configured to be drivable, position recognition unit  152  recognizes the position of discharge mechanism  125 . A method for recognizing the position of the discharge inhibited portion described below can also be applied to the recognition of the position of discharge mechanism  125 . 
     (A) Method 1 for Recognizing Position of Discharge Inhibited Portion 
     For example, the position of the discharge inhibited portion is recognized based on an image obtained from camera  120 . In this case, camera  120  is disposed so as to include the discharge inhibited portion in the field of view of camera  120 . 
       FIG.  6    is a view illustrating an image  60  obtained from camera  120 . Position recognition unit  152  recognizes the position of the discharge inhibited portion from image  60  by executing predetermined image processing. 
     As an example, the position of the discharge inhibited portion is recognized using a learned model. The learned model is previously generated by learning processing using a learning data set. The learning data set includes a plurality of learning images in which the discharge inhibited portion is photographed. Each learning image is associated with a label (alternatively, a label indicating the type of the discharge inhibited portion) indicating whether the discharge inhibited portion is photographed. An internal parameter of the learned model are previously optimized by the learning processing using such the learning data set. 
     Various machine learning algorithms can be adopted as a learning method for generating the learned model. As an example, deep learning, a convolution neural network (CNN), a full-layer convolutional neural network (FCN), a support vector machine, or the like is adopted as a machine learning algorithm. 
     Position recognition unit  152  divides image  60  into a plurality of regions, and inputs partial images of the respective sections to the learned model. As a result, the learned model outputs a probability in which the discharge inhibited portion is included in the input partial image. Position recognition unit  152  recognizes the position of the partial image where the probability exceeds a predetermined value as a position P1 of the discharge inhibited portion. For example, position P1 of discharge inhibited portion  170  is defined by a representative point (for example, a center point of discharge inhibited portion  170 ) in a region representing discharge inhibited portion  170 . Recognized position P1 is output to coolant control unit  156 . 
     The method for recognizing the position of the discharge inhibited portion is not limited to the method using the learned model, but image processing based on a rule base may be adopted. As an example, position recognition unit  152  previously holds a reference image representing the discharge inhibited portion, and scans the reference image in image  60  to calculate similarity with the reference image for each region in image  60 . Then, position recognition unit  152  recognizes a region where the similarity exceeds a predetermined value as position P1 of the discharge inhibited portion. 
     In the embodiment, position recognition unit  152  recognizes position P1 of the discharge inhibited portion using a single algorithm. However, the present invention is not limited to this configuration, but position P1 of the discharge inhibited portion may be recognized by a plurality of algorithms. 
     (B) Method 2 for Recognizing Position of Discharge Inhibited Portion 
     As another example, the position of the discharge inhibited portion is recognized based on a machining program  322  defining a drive instruction for the discharge inhibited portion. For example, machining program  322  defines drive instructions of servo drivers  111 X to  111 Z (see  FIG.  4   ). 
     Typically, machining program  322  includes an instruction code designating a movement destination of the discharge inhibited portion. Position recognition unit  152  recognizes the instruction code currently executed in machining program  322 , and recognizes the movement destination of the discharge inhibited portion included in the instruction code as position P1 of the discharge inhibited portion. Recognized position P1 of the discharge inhibited portion is output to coolant control unit  156 . 
     E2. Chip Recognition Unit  154   
     With reference to  FIG.  7   , a function of chip recognition unit  154  will be described below. 
     Chip recognition unit  154  recognizes the position of the chip in machine tool  100 . The position of the chip may be recognized in any manner. As an example, the position of the chip is recognized based on the image obtained from camera  120 . 
     As an example, the position of the chip is recognized using the learned model. The learned model is previously generated by learning processing using a learning data set. The learning data set includes a plurality of learning images in which the chip is photographed. Each learning image is associated with a label (alternatively, a label indicating the type of chip) indicating whether the chip is illustrated. An internal parameter of the learned model are previously optimized by the learning processing using such the learning data set. 
     Various machine learning algorithms can be adopted as a learning method for generating the learned model. As an example, deep learning, a convolution neural network (CNN), a full-layer convolutional neural network (FCN), a support vector machine, or the like is adopted as a machine learning algorithm. 
     The learned model receives the input of the image obtained from camera  120  and outputs a position P2 of the chip photographed in the image.  FIG.  7    is a view illustrating a chip region recognized from image  60  in  FIG.  6   . 
     More specifically, chip recognition unit  154  divides image  60  into a plurality of regions, and inputs the partial image of each section to the learned model. As a result, the learned model outputs the probability that the input partial image includes the chip. Chip recognition unit  154  recognizes the position of the partial image in which the probability exceeds a predetermined value as chip position P2. Recognized position P2 is output to coolant control unit  156 . 
     The method for recognizing the position of the chip is not limited to the above-described method using the learned model, but the image processing based on the rule base may be adopted. As an example, a frequency component included in the partial image tends to increase as the number of chips increases. Accordingly, chip recognition unit  154  performs frequency analysis such as fast Fourier transform (FFT) and acquires a spectral image for each partial image. Each pixel value of the spectrum image represents a correlation value with the waveform of each frequency. Chip recognition unit  154  recognizes a region of the partial image in which the pixel value exceeds a predetermined value in a predetermined high-frequency band as chip position P2. 
     In the embodiment, chip recognition unit  154  recognizes position P2 of the chip using a single algorithm. However, the present invention is not limited to this configuration, but chip position P2 may be recognized by a plurality of algorithms. 
     E3. Coolant Control Unit  156   
     A function of coolant control unit  156  will be described below. 
     Coolant control unit  156  controls the discharge of the coolant by discharge mechanism  125  such that the coolant is not discharged to the discharge inhibited portion based on position P1 (see  FIG.  6   ) of the discharge inhibited portion recognized by position recognition unit  152 . Accordingly, the coolant can be prevented from adhering to the discharge inhibited portion. 
     As more specific processing, coolant control unit  156  transforms position P1 indicated in the first coordinate system into the second coordinate system based on a predetermined coordinate transformation matrix for transformation from a coordinate system (hereinafter, also referred to as a “first coordinate system”) based on camera  120  to a coordinate system (hereinafter, also referred to as a “second coordinate system”) in machining area AR (see  FIGS.  2  and  3   ). Subsequently, coolant control unit  156  acquires the position of discharge mechanism  125  from predetermined installation position information  324 . For example, the position of discharge mechanism  125  is indicated by the second coordinate system. Coolant control unit  156  calculates a discharge exclusion angle of the coolant by discharge mechanism  125  based on position P1 of the discharge inhibited portion indicated by the second coordinate system and the position of discharge mechanism  125  indicated by the second coordinate system. Thereafter, coolant control unit  156  controls the discharge direction of the coolant by discharge mechanism  125  so as to exclude the calculated discharge exclusion angle. The discharge direction of the coolant can be changed by controlling stepping motors  112 A 1 ,  112 A 2 ,  112 B 1 ,  112 B 2 . 
     Preferably, coolant control unit  156  produces a coolant cleaning path R by discharge mechanism  125  based on each of chip positions P2 (see  FIG.  7   ) recognized by chip recognition unit  154 . Typically, coolant control unit  156  produces cleaning path R so as to pass through each of chip positions P2.  FIG.  8    is a view illustrating cleaning path R by discharge mechanism  125 . 
     Thereafter, coolant control unit  156  controls the discharge direction of the coolant by discharge mechanism  125  according to produced cleaning path R. At this time, coolant control unit  156  produces cleaning path R so as to avoid position P1 of the discharge inhibited portion. Alternatively, coolant control unit  156  may turn off the discharge of the coolant when the discharge port of the coolant in discharge mechanism  125  faces the direction of position P1 of the discharge inhibited portion. 
     With reference to  FIG.  9   , the function of coolant control unit  156  will be further described.  FIG.  9    is a view illustrating a positional relationship among discharge mechanism  125 A, discharge inhibited portion  170 , and a chip G of the workpiece. 
     As illustrated in  FIG.  9   , sometimes discharge inhibited portion  170  is located between discharge mechanism  125 A and chip G. In this case, when discharge mechanism  125 A discharges the coolant toward chip G, the coolant adheres to discharge inhibited portion  170 . Accordingly, when discharge inhibited portion  170  is located between discharge mechanism  125 A and chip G, controller  50  of machine tool  100  moves discharge inhibited portion  170  such that discharge inhibited portion  170  is not located between discharge mechanism  125 A and chip G, and starts the discharge of the coolant by discharge mechanism  125 A after the movement. In the example of  FIG.  9   , coolant control unit  156  discharges a coolant C toward chip G after moving discharge inhibited portion  170  in the X-direction. 
     As more specific processing, coolant control unit  156  acquires position P1 of discharge inhibited portion  170  from position recognition unit  152 . Furthermore, coolant control unit  156  acquires position P2 of chip G from chip recognition unit  154 . Coolant control unit  156  further acquires information indicating the position (hereinafter, also referred to as a “position P3”) of discharge mechanism  125 A. 
     Thereafter, coolant control unit  156  determines whether discharge inhibited portion  170  is located between chip G and discharge mechanism  125 A based on position P1 of discharge inhibited portion  170 , position P2 of chip G, and position P3 of discharge mechanism  125 A. As an example, coolant control unit  156  calculates a first direction from position P3 of discharge mechanism  125 A toward position P1 of discharge inhibited portion  170  and a second direction from position P3 of discharge mechanism  125 A toward position P2 of chip G. Thereafter, coolant control unit  156  calculates an angle between the first direction and the second direction, and determines that discharge inhibited portion  170  is located between chip G and discharge mechanism  125 A when the calculated angle is less than or equal to a predetermined angle (for example, less than or equal to 10 degrees). In this case, coolant control unit  156  starts the discharge of coolant C after driving discharge inhibited portion  170 . Accordingly, coolant control unit  156  can remove chip G while preventing coolant C from being discharged to discharge inhibited portion  170 . 
     With reference to  FIG.  10   , the function of coolant control unit  156  will be further described.  FIG.  10    is a view illustrating the positional relationship among discharge mechanism  125 A,  125 B, discharge inhibited portion  170 , and chip G of the workpiece. 
     As illustrated in  FIG.  10   , when a plurality of discharge mechanisms  125  (for example, discharge mechanisms  125 A,  125 B) are provided in machine tool  100 , coolant control unit  156  selectively controls the discharge of the coolant by discharge mechanism  125 A (first discharge unit) and the discharge of the coolant by discharge mechanism  125 B (second discharge unit) such that the coolant is not discharged to discharge inhibited portion  170 . 
     More specifically, coolant control unit  156  calculates the angle between the direction from a position P3A of discharge mechanism  125 A toward position P1 of discharge inhibited portion  170  and the direction from position P3A of discharge mechanism  125 A toward position P2 of chip G. When the angle is less than or equal to a predetermined angle (for example, less than or equal to 10 degrees), coolant control unit  156  inhibits the discharge of the coolant by discharge mechanism  125 A. 
     Similarly, coolant control unit  156  calculates the angle between the direction from a position P3B of discharge mechanism  125 B toward position P1 of discharge inhibited portion  170  and the direction from position P3B of discharge mechanism  125 B toward position P2 of chip G. When the angle is greater than a predetermined angle (for example, 10 degrees), coolant control unit  156  controls the angle of the discharge port of discharge mechanism  125 B so as to face position P2 of chip G, and executes the discharge of the coolant by discharge mechanism  125 B. The angle of the discharge port of discharge mechanism  125 B is adjusted by driving and controlling stepping motors  112 B 1 ,  112 B 2 . 
     As described above, coolant control unit  156  controls at least one of on and off of the coolant discharge and the coolant discharge direction for each of discharge mechanisms  125 A,  125 B such that the coolant is not discharged to discharge inhibited portion  170 . Accordingly, coolant control unit  156  can remove chip G without driving discharge inhibited portion  170 . 
     F. Hardware Configuration of Controller  50   
     With reference to  FIG.  11   , a hardware configuration of controller  50  in  FIG.  4    will be described below.  FIG.  11    is a view illustrating an example of the hardware configuration of controller  50 . 
     As illustrated in  FIG.  11   , controller  50  includes CPU unit  20  and CNC unit  30 . For example, CPU unit  20  and CNC unit  30  are connected to each other through communication path B. 
     Hereinafter, the hardware configuration of CPU unit  20  and the hardware configuration of CNC unit  30  will be described in order. 
     F1. Hardware Configuration of CPU Unit  20   
     CPU unit  20  includes a processor  201 , a read only memory (ROM)  202 , a random access memory (RAM)  203 , communication interfaces  204 ,  205 , and an auxiliary storage device  220 . These components are connected to an internal bus  209 . 
     For example, processor  201  is constructed with at least one integrated circuit. For example, the integrated circuit may be constructed with at least one CPU, at least one graphics processing unit (GPU), at least one application specific integrated circuit (ASIC), at least one field programmable gate array (FPGA), or a combination thereof. 
     Processor  201  controls the operations of CPU unit  20  by executing various programs such as a control program  222 . Control program  222  defines instructions controlling various devices in machine tool  100 . Processor  201  reads control program  222  from auxiliary storage device  220  or ROM  202  to RAM  203  based on the reception of the execution instruction of control program  222 . RAM  203  functions as a working memory, and temporarily stores various data required for the execution of control program  222 . 
     Communication interface  204  is an interface that implements the communication using a local area network (LAN) cable, a wireless LAN (WLAN), Bluetooth (registered trademark), or the like. As an example, CPU unit  20  implements the communication with an external device such as motor drivers  111 A,  111 B through a communication interface  305 . 
     Communication interface  205  is an interface implementing the communication with various units connected to the fieldbus. CNC unit  30  or an I/O unit (not illustrated) can be cited as an example of the unit connected to the fieldbus. 
     The auxiliary storage device  220  is an example of the above-described storage device  160  (see  FIG.  5   ). For example, auxiliary storage device  220  is a storage medium such as a hard disk or a flash memory. Auxiliary storage device  220  stores control program  222  and the like. The storage location of control program  222  is not limited to auxiliary storage device  220 , but may be stored in the storage area (for example, a cache memory) of processor  201 , ROM  202 , RAM  203 , the external device (for example, a server), or the like. 
     Control program  222  may be provided not as a stand-alone program, but as a part of an arbitrary program. In this case, various pieces of processing of the embodiment is performed in cooperation with an arbitrary program. Even a program that does not include such a part of modules does not deviate from the purpose of control program  222  of the embodiment. Furthermore, some or all of the functions provided by control program  222  may be performed by dedicated hardware. Further, CPU unit  20  may be configured in a form of what is called cloud service in which at least one server executes a part of the processing of control program  222 . 
     F2. Hardware Configuration of Cpu Unit  20   
     With reference to  FIG.  11   , the hardware configuration of CNC unit  30  will be described below. 
     CNC unit  30  includes a processor  301 , a ROM  302 , a RAM  303 , a communication interface  305 , a communication interface  305 , and an auxiliary storage device  320 . These components are connected to an internal bus  309 . 
     For example, processor  301  is constructed with at least one integrated circuit. For example, the integrated circuit may be constructed with at least one CPU, at least one ASIC, at least one FPGA, or a combination thereof. 
     Processor  301  controls the operation of CNC unit  30  by executing various programs such as machining program  322 . Machining program  322  is a program implementing workpiece machining. Processor  301  reads machining program  322  from ROM  302  in RAM  303  based on the reception of the execution instruction of machining program  322 . RAM  303  functions as a working memory, and temporarily stores various data required for the execution of machining program  322 . 
     Communication interface  305  is an interface that implements the communication using LAN, WLAN, Bluetooth, or the like. As an example, CNC unit  30  implements the communication with CPU unit  20  through communication interface  305 . In addition, CNC unit  30  implements the communication with various drive units (for example, servo drivers  111 R,  111 X to  111 Z, and the like) for the workpiece machining through communication interface  305  or another communication interface. 
     For example, auxiliary storage device  320  is a storage medium such as a hard disk or a flash memory. Auxiliary storage device  320  stores a machining program  322 , various installation position information  324 , and the like. 
     For example, machining program  322  is described by an NC program. For example, machining program  322  includes an instruction code specifying a movement destination of spindle  132  in the X- to Z-directions, an instruction code specifying a coolant discharge direction by discharge mechanism  125 , and an instruction code specifying on and off of the coolant discharge by discharge mechanism  125 . 
     Installation position information  324  includes position information about various devices in machine tool  100 . As an example, installation position information  324  includes position information about discharge mechanism  125 , position information (not illustrated) about camera  120 , and the like. 
     The storage location of machining program  322  or installation position information  324  is not limited to auxiliary storage device  320 , but may be stored in the storage area (for example, the cache memory) of processor  301 , ROM  302 , RAM  303 , the external device (for example, the server), and the like. 
     Machining program  322  may be provided not as a stand-alone program, but as a part of an arbitrary program. In this case, various pieces of processing of the embodiment is performed in cooperation with an arbitrary program. Even a program that does not include such a part of modules does not deviate from the purpose of machining program  322  of the embodiment. Furthermore, some or all of the functions provided by machining program  322  may be performed by dedicated hardware. Furthermore, CNC unit  30  may be configured in a form of what is called cloud service in which at least one server executes a part of the processing of machining program  322 . 
     G. Control Structure of Controller  50   
     With reference to  FIG.  12   , a flowchart related to coolant control will be described.  FIG.  12    is the flowchart illustrating an example of the coolant control. For example, the processing in  FIG.  12    is executed by controller  50  of machine tool  100 . 
     In step S 110 , controller  50  functions as position recognition unit  152  (see  FIG.  5   ), and recognizes position P1 of the discharge inhibited portion in machine tool  100 . Because the function of position recognition unit  152  is as described above, the description thereof will not be repeated. At the time of step S 110 , recognized position P1 of the discharge inhibited portion is represented by the coordinate system (that is, the first coordinate system) based on camera  120 . 
     In step S 112 , controller  50  functions as chip recognition unit  154  (see  FIG.  5   ) and recognizes position P2 of chip G of the workpiece in machine tool  100 . Since the function of chip recognition unit  154  is as described above, the description thereof will not be repeated. At the time of step S 112 , recognized position P2 of the chip is represented by the coordinate system (that is, the first coordinate system) based on camera  120 . 
     In step S 114 , controller  50  acquires position P3 of discharge mechanism  125  in machine tool  100 . Typically, position P3 of discharge mechanism  125  is defined by installation position information  324  (see  FIG.  11   ). For example, position P3 of discharge mechanism  125  is indicated by the coordinate system (that is, the second coordinate system) in machining area AR (See  FIGS.  2  and  3   ). 
     In step S 116 , controller  50  functions as coolant control unit  156  (see  FIG.  5   ), and controls discharge mechanism  125  such that the coolant does not adhere to the discharge inhibited portion. More specifically, controller  50  transforms position P1 of the discharge inhibited portion recognized in step S 112  and position P2 of the chip recognized in step S 114  from the first coordinate system to the second coordinate system based on a predetermined coordinate transformation matrix for the transformation from the first coordinate system to the second coordinate system. Subsequently, coolant control unit  156  of controller  50  controls discharge mechanism  125  such that the coolant does not adhere to the discharge inhibited portion based on position P1 of the discharge inhibited portion indicated by the second coordinate system, position P2 of the chip indicated by the second coordinate system, and position P3 of discharge mechanism  125  indicated by the second coordinate system. 
     H. Summary 
     As described above, machine tool  100  of the embodiment recognizes the position of the discharge inhibited portion, and controls the discharge of the coolant by discharge mechanism  125  such that the coolant is not discharged to the discharge inhibited portion. Accordingly, machine tool  100  can prevent the coolant from adhering to the discharge inhibited portion in which the position changes each time. 
     It should be considered that the disclosed embodiment is an example in all respects and not restrictive. The scope of the present invention is defined by not the description above, but the claims, and it is intended that all modifications within the meaning and scope of the claims are included in the present invention. 
     
       
         
           
               
               
             
               
                 Reference Sign List 
               
             
            
               
                   20 : 
                 CPU unit 
               
               
                   30 : 
                 CNC unit 
               
               
                   50 : 
                 controller 
               
               
                   60 : 
                 image 
               
               
                   100 : 
                 machine tool 
               
               
                   111 A,  111 B: 
                 motor driver 
               
               
                   111 R,  111 X,  111 Y,  111 Z: 
                 servo driver 
               
               
                   112 A 1 ,  112 A 2 ,  112 B 1 ,  112 B 2 : 
                 stepping motor 
               
               
                   112 R,  112 X,  112 Y,  112 Z: 
                 servomotor 
               
               
                   113 : 
                 moving body 
               
               
                   120 ,  120 A,  120 B: 
                 camera 
               
               
                   125 ,  125 A,  125 B: 
                 discharge mechanism 
               
               
                   127 : 
                 collection mechanism 
               
               
                   130 : 
                 cover 
               
               
                   131 : 
                 spindle head 
               
               
                   132 : 
                 spindle 
               
               
                   133 : 
                 housing 
               
               
                   134 : 
                 tool 
               
               
                   136 : 
                 table 
               
               
                   140 : 
                 operation panel 
               
               
                   142 : 
                 display 
               
               
                   152 : 
                 position recognition unit 
               
               
                   154 : 
                 chip recognition unit 
               
               
                   156 : 
                 coolant control unit 
               
               
                   160 : 
                 storage device 
               
               
                   170 : 
                 discharge inhibited portion 
               
               
                   201 ,  301 : 
                 processor 
               
               
                   202 ,  302 : 
                 ROM 
               
               
                   203 ,  303 : 
                 RAM 
               
               
                   204 ,  205 ,  305 : 
                 communication interface 
               
               
                   209 ,  309 : 
                 internal bus 
               
               
                   220 ,  320 : 
                 auxiliary storage device 
               
               
                   222 : 
                 control program 
               
               
                   322 : 
                 machining program 
               
               
                   324 : 
                 installation position information