阅读说明：本技术 对异物侵入到配置于机床的电动机的内部进行检测的异物检测装置 (Foreign matter detection device for detecting intrusion of foreign matter into motor disposed in machine tool ) 是由 明石广大 于 2020-01-23 设计创作，主要内容包括：本发明提供一种对异物侵入到配置于机床的电动机的内部进行检测的异物检测装置。异物检测装置具有：离子传感器,其配置于进给轴马达的内部。离子传感器形成为对包含在切削液中的离子进行检测。机械控制装置根据离子传感器的输出,来判定离子浓度是否在与切削液相关的判定范围内,当离子浓度在与切削液相关的判定范围内时,判定为切削液侵入到进给轴马达的内部。(The invention provides a foreign matter detection device for detecting the intrusion of foreign matter into a motor disposed in a machine tool. The foreign matter detection device has: and an ion sensor disposed inside the feed shaft motor. The ion sensor is configured to detect ions contained in the cutting fluid. The machine control device determines whether the ion concentration is within a determination range relating to the cutting fluid based on the output of the ion sensor, and determines that the cutting fluid enters the feed shaft motor when the ion concentration is within the determination range relating to the cutting fluid.)

1. A foreign matter detection device for detecting intrusion of foreign matter into a motor disposed in a machine tool,

the foreign matter detection device includes:

a sensor disposed inside the motor; and

a control device for determining whether or not foreign matter intrudes into the motor based on an output of the sensor,

the sensor is formed to detect a physical property possessed by the foreign matter,

the control device includes:

a storage unit that stores physical property information of a foreign object; and

and a determination unit that determines the intrusion of the foreign object and the type of the foreign object by comparing the output of the sensor with the physical property information of the foreign object.

2. The foreign matter detection device according to claim 1,

the sensor is an ion sensor for detecting ions corresponding to a substance contained in the cutting fluid,

the physical property information of the foreign matter is a determination range of ion concentration related to the cutting fluid,

the determination unit determines whether or not the ion concentration is within a determination range relating to the cutting fluid based on the output of the ion sensor, and determines that the cutting fluid enters the motor when the ion concentration is within the determination range relating to the cutting fluid.

3. The foreign matter detection device according to claim 1,

the sensor is a pH sensor that detects pH,

the physical property information of the foreign matter is a determination range of the pH value relating to the cutting fluid,

the determination unit determines whether or not the pH value is within a determination range relating to the cutting fluid based on an output of the pH sensor, and determines that the cutting fluid enters the motor when the pH value is within the determination range relating to the cutting fluid.

4. The foreign matter detection device according to claim 1,

the sensor is a gas sensor or an odor sensor that detects a gas corresponding to a substance contained in the cutting fluid,

the physical property information of the foreign matter is a determination range of the concentration of the gas related to the cutting fluid,

the determination unit determines whether or not the concentration of the gas is within a determination range relating to the cutting fluid based on an output of the gas sensor or the odor sensor, and determines that the cutting fluid enters the motor when the concentration of the gas is within the determination range relating to the cutting fluid.

5. The foreign matter detection device according to claim 1,

the machine tool is configured to spray a water-soluble cutting fluid to a workpiece,

the sensor is a humidity sensor and the humidity sensor,

the physical property information of the foreign matter is a determination range of humidity relating to the water-soluble cutting fluid,

the determination unit determines whether or not the humidity inside the motor is within a determination range relating to the cutting fluid based on the output of the humidity sensor, and determines that the water-soluble cutting fluid enters the motor when the humidity is within the determination range relating to the cutting fluid.

6. The foreign matter detection device according to claim 1,

the machine tool processes a workpiece having magnetic properties,

the sensor is a proximity sensor that detects proximity of an object having magnetism,

the physical property information of the foreign object is a determination range of a distance of the object from the proximity sensor,

the determination unit determines whether or not the object approaches within a determination range of the distance based on an output of the proximity sensor, and determines that chips generated when the workpiece is machined intrude into the motor when the object approaches within the determination range of the distance.

7. The foreign matter detection device according to claim 1,

the sensor is an ion sensor for detecting ions corresponding to a substance contained in the lubricating oil,

the physical property information of the foreign matter is a determination range of the ion concentration related to the lubricating oil,

the determination unit determines whether or not the ion concentration is within a determination range relating to the lubricating oil based on the output of the ion sensor, and determines that the lubricating oil enters the motor when the ion concentration is within the determination range relating to the lubricating oil.

8. The foreign matter detection device according to claim 1,

the sensor is a pH sensor that detects pH,

the physical property information of the foreign matter is a determination range of the pH value relating to the lubricating oil,

the determination unit determines whether or not the pH value is within a determination range relating to the lubricating oil based on the output of the pH sensor, and determines that the lubricating oil has entered the interior of the motor when the pH value is within the determination range relating to the lubricating oil.

9. The foreign matter detection device according to any one of claims 2, 3, 7, and 8,

the motor includes a plurality of components that isolate the exterior and interior of the motor,

the sensor is disposed in the vicinity of a portion where the plurality of members contact each other.

10. The foreign matter detection device according to claim 1,

the foreign matter detection device includes: a plurality of sensors for determining the invasion of a predetermined specific foreign matter,

the plurality of sensors include sensors of different kinds from each other,

the determination unit determines the intrusion of foreign matter and the type of foreign matter for the output of each sensor, and determines that foreign matter intrudes into the motor when it is determined that foreign matter intrudes into the output of at least one of the plurality of sensors.

11. The foreign matter detection device according to claim 1,

the foreign matter detection device includes: a plurality of sensors for determining the invasion of a predetermined specific foreign matter,

the plurality of sensors include sensors of different kinds from each other,

the determination unit determines the intrusion of foreign matter and the type of foreign matter for the outputs of the sensors, determines that foreign matter intrudes into the motor when determining that foreign matter intrudes into the outputs of all the sensors, and determines that foreign matter does not intrude into the motor when determining that foreign matter does not intrude into the outputs of at least one of the plurality of sensors.

12. The foreign matter detection device according to claim 1,

the sensor is a pH sensor that detects pH,

the physical property information of the foreign matter is a determination range of a pH value relating to the cutting fluid and a determination range of a pH value relating to the lubricating oil,

the judgment range relating to the cutting fluid is a range not overlapping with the judgment range relating to the lubricating oil,

the determination unit determines whether the pH value is within a determination range for the cutting fluid or within a determination range for the lubricating oil based on an output of the pH sensor, determines that the cutting fluid enters the motor when the pH value is within the determination range for the cutting fluid, and determines that the lubricating oil enters the motor when the pH value is within the determination range for the lubricating oil.

Technical Field

The present invention relates to a foreign object detection device that detects intrusion of a foreign object into a motor disposed in a machine tool.

Background

Conventionally, it is known to use a motor for moving or rotating a component of an apparatus. Devices with motors are used in a variety of environments. For example, the motor is sometimes used in an environment where much dust, flying dust, or the like exists. At this time, foreign matter such as dust or fly ash may enter the motor to cause a motor failure.

Preferably, the means for controlling the motor is capable of detecting the intrusion of the foreign matter into the motor. In the prior art, it is known that: in an electric circuit for driving a motor, intrusion of foreign matter into a bearing or the like is detected by detecting voltage, impedance, or the like (see, for example, japanese patent laid-open nos. 2002-131187 and 2017-34858). Alternatively, the following methods are known: foreign matter is detected by forming a part of an electric circuit in a bearing of a motor (see, for example, japanese unexamined patent publication No. 50-106607).

Further, it is known that: in order to detect an abnormality of a component of the apparatus, a sensor is disposed in the apparatus. For example, it is known that: in order to detect breakage of an oil seal disposed in a motor, a temperature detector is disposed in the motor (see, for example, japanese patent application laid-open No. 2004-242416). Alternatively, it is known that: in a spindle head of a machine tool, a sensor is disposed in the spindle head in order to determine a component in which an abnormality has occurred (see, for example, japanese patent application laid-open No. 2018-187703).

It is known that: when a workpiece is cut or ground, the workpiece is machined by a machine tool. Chips are generated when a workpiece is machined by a machine tool. Further, when machining a workpiece, a cutting fluid may be supplied to a portion where the workpiece is machined. The chips and the cutting fluid splash around the portion to be machined. Therefore, a machining room, which is a room for machining a workpiece, may be disposed in the machine tool. The machining chamber is formed such that chips and cutting fluid are not splashed to the outside.

A motor may be disposed inside a processing chamber of a machine tool. For example, a spindle motor for rotating a spindle holding a tool is disposed inside the processing chamber. Alternatively, a feed shaft motor for moving a table on which a workpiece is fixed and a feed shaft motor for moving a member on which a spindle head is fixed are disposed inside the processing chamber. Such motors are used in environments where there are a lot of chips and cutting fluid. As a result, foreign matter is likely to enter the motor.

When foreign matter enters the interior of the motor, the performance of the motor may be degraded or a malfunction may occur. There are problems that the performance of the motor is deteriorated and the machine tool has to be stopped when the motor fails. Therefore, it is preferable that the intrusion of the foreign matter into the motor be detected with high accuracy.

Disclosure of Invention

One aspect of the present disclosure provides a foreign object detection device that detects intrusion of a foreign object into a motor disposed in a machine tool. The foreign matter detection device has: and a sensor disposed inside the motor. The foreign matter detection device has: and a control device for determining whether or not foreign matter enters the motor based on the output of the sensor. The sensor is formed to detect a physical property possessed by the foreign matter. The control device includes: a storage unit that stores physical property information of a foreign object; and a determination unit that determines the intrusion of the foreign object and the type of the foreign object by comparing the output of the sensor with the physical property information of the foreign object.

Drawings

Fig. 1 is a block diagram of a machine tool including a foreign object detection device 1 in the embodiment.

Fig. 2 is a schematic cross-sectional view of a feed shaft motor in which a sensor of the foreign matter detection device 1 is disposed in the embodiment.

Fig. 3 is a block diagram of a machine tool having the 2 nd foreign matter detection device in the embodiment.

Fig. 4 is a schematic cross-sectional view of a feed shaft motor in which a sensor of the 2 nd foreign matter detection device is disposed in the embodiment.

Detailed Description

A foreign object detection device for detecting the intrusion of a foreign object in the embodiment will be described with reference to fig. 1 to 4. The foreign object detection device of the present embodiment determines that foreign objects intrude into the motor of the machine tool, and determines the type of the intruding foreign objects.

Fig. 1 is a block diagram of a machine tool according to the present embodiment. The machine tool 1 machines a workpiece while changing the relative position of a tool with respect to the workpiece. The machine tool 1 has a feed axis that changes the relative position of a tool with respect to a workpiece. For example, the feed shaft is constituted by 3 linear shafts (X-axis, Y-axis, and Z-axis). The feed shaft of the machine tool 1 is not limited to this form, and may be configured by any linear or rotary feed shaft.

The machine tool 1 has a moving device 5 that moves a workpiece or a tool along a feed axis. The mobile device 5 includes: and a feed shaft motor 31 disposed to correspond to each feed shaft. The machine tool 1 includes: the spindle head 6 rotates a tool while holding the tool. The spindle head 6 includes a spindle for supporting a tool and a spindle motor 32 for rotating the spindle.

The machine tool 1 includes a machine control device 2 that controls a feed shaft motor 31 and a main shaft motor 32. The machine control device 2 of the present embodiment includes an arithmetic Processing unit (computer) having a cpu (central Processing unit) as a processor. The arithmetic processing device includes a ram (random Access memory) and a rom (read Only memory) connected to the CPU via a bus.

The machine tool 1 of the present embodiment is of a numerical control type. A machining program 7 for operating the machine tool 1 is generated in advance by an operator. The machine control device 2 includes: a storage unit 3 for storing information relating to machining, such as a machining program 7 and a determination range; and a command generation unit 4 for generating a motor operation command based on the machining program 7. The storage unit 3 may be constituted by a storage medium capable of storing information, such as a volatile memory, a nonvolatile memory, or a hard disk. The command generating unit 4 corresponds to a processor driven in accordance with the machining program 7. The command generating unit 4 is formed to be able to read information stored in the storage unit 3. The processor functions as the command generating unit 4 by reading the machining program 7 and performing control determined by the machining program 7.

The machine tool 1 includes: and a motor drive device 33 for supplying power to the feed shaft motor 31 and the main shaft motor 32 in accordance with the operation command generated by the machine control device 2. The feed shaft motor 31 and the spindle motor 32 are driven by power supplied from the motor drive device 33.

The machine control device 2 includes an input unit 8 for an operator to input information related to machining. The input unit 8 is constituted by an input device such as a keyboard, a dial, or a mouse. The machine control device 2 includes a display unit 9 that displays information related to machining. The display unit 9 is formed of a display such as a liquid crystal display panel.

Fig. 2 is a schematic partial cross-sectional view of a motor provided with a sensor of the foreign object detection device 1 in the present embodiment. The motor of the present embodiment is disposed in a machine tool. In the present embodiment, the feed shaft motor 31 is exemplified as the electric motor. The feed shaft motor 31 has a rotor 11 and a stator 12. The stator 12 includes, for example: and a stator core 27 formed of a plurality of magnetic steel plates stacked in the axial direction. The stator core 27 is wound with the coil 16. The rotor 11 includes: a shaft 13 formed in a rod shape; a rotor core 17 fixed to an outer peripheral surface of the shaft 13; and a magnet 18 disposed inside the rotor core 17. The magnet 18 of the present embodiment is a permanent magnet. The shaft 13 is connected to other members for transmitting rotational force. The shaft 13 rotates about a rotational axis RA. In the present embodiment, the side where the shaft 13 is connected to other members in the extending direction of the rotation axis RA is referred to as a front side. The side opposite to the front side is referred to as a rear side. In the example shown in fig. 2, an arrow 81 indicates the front side of the feed shaft motor 31.

The feed shaft motor 31 includes a front housing 21 and a rear housing 22 as housings. The housings 21 and 22 are formed in a cylindrical shape. The stator 12 is fixed to the housings 21 and 22 by fastening members such as bolts. The housings 21 and 22 rotatably support the rotor 11 via bearings 14 and 15. The housing 21 supports the bearing 14. A bearing support member 26 that supports the bearing 15 is fixed to the housing 22. An oil seal 20 for suppressing intrusion of foreign matter is disposed between the end portion of the front side of the housing 21 and the shaft 13.

An encoder 19 for detecting the rotational position or the number of rotations of the shaft 13 is disposed at the rear end of the shaft 13. A rear cover 23 that closes the space inside the housing 22 is fixed to an end portion on the rear side of the housing 22.

Referring to fig. 1 and 2, a machine tool 1 includes: the 1 st foreign matter detection device 51 detects intrusion of foreign matter into a motor disposed in the machine tool 1. The 1 st foreign matter detection device 51 of the present embodiment detects the intrusion of foreign matter into the feed shaft motor 31.

The feed shaft motor 31 of the present embodiment is disposed inside the processing chamber of the machine tool 1. The process chamber is surrounded by components that form walls, referred to as baffles. When a workpiece is machined, chips are generated. Further, when machining a workpiece, a cutting fluid is supplied for cooling the workpiece or reducing friction between the workpiece and a tool. Alternatively, the cutting fluid has a function of removing chips remaining in the vicinity of the machining point of the workpiece. For example, the cutting fluid is ejected from a nozzle disposed in the machine tool 1 to a portion to be machined of a workpiece.

Much cutting fluid and chips are scattered inside the machining chamber. Foreign matter such as cutting fluid and chips is present around the feed shaft motor 31. Further, a reduction gear may be connected to the feed shaft motor 31. Lubricating oil is disposed inside the speed reducer. The foreign matter detection device of the present embodiment detects the intrusion of at least 1 foreign matter out of the cutting fluid, the chips, and the lubricating oil into the feed shaft motor 31.

The 1 st foreign matter detection device 51 detects the intrusion of the cutting fluid. The foreign matter detection device 51 has a sensor disposed inside the feed shaft motor 31. A plurality of sensors are disposed in the foreign object detection device 51. The foreign matter detection device 51 includes: humidity sensor 41, ion sensor 42, pH sensor 43, gas sensor 44, and odor sensor 45. The foreign matter detection device 51 includes: and a control device for determining whether or not foreign matter enters the feed shaft motor 31 based on an output of the sensor. In the present embodiment, the machine control device 2 functions as a control device that determines the intrusion of foreign matter. Further, a sensor for acquiring a predetermined signal is disposed inside the motor, while an electric circuit for processing a signal acquired from the sensor may be disposed outside the motor.

The sensor disposed inside the feed shaft motor 31 is formed to detect physical properties of foreign matter that may intrude into the feed shaft motor 31. The machine control device 2 stores physical property information of the foreign object in the storage unit 3. The information related to the physical property of the foreign object includes, for example, a determination range related to a physical property value of the foreign object. The operator creates information relating to the physical properties of the foreign matter in advance. The operator inputs information on the physical properties of the foreign matter into the storage unit 3 via the input unit 8.

The machine control device 2 includes: and a determination unit 10 that determines the entry of foreign matter into the feed shaft motor 31 and the type of foreign matter entering. The determination unit 10 corresponds to a processor that drives in accordance with the machining program 7. The processor reads the machining program 7 and performs control determined by the machining program 7, thereby functioning as the determination unit 10.

The determination unit 10 acquires physical property information of the foreign object from the storage unit 3. The determination unit 10 acquires the output of each sensor. The determination unit 10 determines the intrusion of the foreign object and the type of the foreign object by comparing the output of the sensor with the physical property information of the foreign object. That is, the determination unit 10 determines whether or not a specific foreign object has entered the motor.

In the control of the present embodiment, the determination unit 10 determines whether or not the physical property value is within the determination range relating to the foreign matter, based on the output of the sensor. The determination range relating to the foreign matter is set in advance and stored in the storage unit 3. When the physical property value based on the output of the sensor is within the determination range relating to the foreign object, the determination unit 10 determines that the foreign object enters the interior of the motor. The determination range of each physical property value may be set in advance by an operator.

The determination by the determination unit 10 is not limited to this embodiment. For example, as the physical property information of the foreign object, a determination range of the rising speed of the physical property value of the foreign object may be stored in the storage unit 3. The determination unit 10 may calculate the rising speed of the physical property value of the foreign matter based on the output of the sensor. When the rising speed is within the determination range, the determination unit 10 may determine that foreign matter has entered. Alternatively, as the physical property information of the foreign matter, whether or not a predetermined substance is contained may be stored in the storage unit 3. The determination unit 10 may determine that foreign matter has entered when a predetermined substance is detected based on the output of the sensor.

The determination unit 10 may acquire the output of the sensor at an arbitrary date and time, and determine the intrusion of the foreign object and the type of the foreign object. For example, the determination unit 10 may perform the determination while the feed shaft motor 31 is being driven. Alternatively, the determination unit 10 may determine during the period in which the workpiece is being machined, that is, during the period in which the cutting fluid, the chips, and the like are present in the machining chamber to a large extent. Alternatively, the determination unit 10 may perform the determination while the foreign matter to be detected is generated. For example, when the foreign matter is a cutting fluid, the determination unit 10 may determine the intrusion of the cutting fluid while the cutting fluid is being ejected from a nozzle that supplies the cutting fluid to the workpiece.

When the judgment by the judgment unit 10 detects that a specific foreign object has entered the interior of the motor, the display unit 9 can display information on a component that may be deteriorated or broken down by the specific foreign object. The relationship between a specific foreign substance and a component that is likely to deteriorate or fail is stored in the storage section 3. Alternatively, the display unit 9 may display a warning to the operator. The operator can repair the feed shaft motor 31 or prepare for replacement of the component by seeing the warning displayed on the display portion 9.

Next, control for detecting intrusion of foreign matter based on the outputs of the sensors will be described. The foreign object detection device 51 of the present embodiment includes a plurality of sensors, but is not limited to this embodiment. The foreign substance detection device 51 may also include at least one sensor.

The foreign matter detection device 51 includes a humidity sensor 41 as a sensor for detecting physical properties of foreign matter. The humidity sensor 41 detects the humidity of the air inside the feed shaft motor 31. The cutting fluid for machine tools includes water-soluble cutting fluids and water-insoluble cutting fluids. In the example here, a water-soluble cutting fluid is used. The water-soluble cutting fluid is diluted with water and thus contains water in the composition. The space inside the feed shaft motor 31 is sealed. When the water-soluble cutting fluid enters the feed shaft motor 31, the humidity of the space inside the feed shaft motor 31 increases.

The storage unit 3 stores the determination range of the humidity of the water-soluble cutting fluid as the physical property information of the foreign matter. The determination unit 10 determines whether or not the humidity inside the feed shaft motor 31 is within a determination range relating to the cutting fluid, based on the output of the humidity sensor 41. For example, the humidity sensor 41 detects the humidity inside the feed shaft motor 31. The determination unit 10 determines whether or not the humidity detected by the humidity sensor 41 is greater than a determination value of the humidity related to the cutting fluid. When the humidity is higher than a judgment value relating to the cutting fluid, the judgment part 10 judges that the water-soluble cutting fluid enters the motor.

Alternatively, as the physical property information of the foreign matter, a determination range relating to the rising speed of the humidity may be stored. The determination unit 10 may determine that the water-soluble cutting fluid enters the feed shaft motor 31 when the humidity acquired by the humidity sensor 41 increases at a speed greater than a predetermined determination value.

When the cutting fluid determined to be water-soluble enters the feed shaft motor 31, the display unit 9 displays the entry of the cutting fluid. The display unit 9 displays information on a member that may be deteriorated or broken down by contact with the water-soluble cutting fluid. For example, the display unit 9 displays information that there is a possibility that insulation failure occurs in a winding used for a component such as the coil 16. Alternatively, the display unit 9 may display information that there is a possibility that components such as the bearings 14 and 15, the rotor core 17, or the stator core 27 may rust.

Inside the feed shaft motor 31, air inside the feed shaft motor 31 is agitated due to the rotation of the rotor 11. The humidity of the space inside the feed shaft motor 31 is substantially constant. Therefore, the humidity sensor 41 can be disposed at any position in the internal space of the feed shaft motor 31. In the example shown in fig. 2, the humidity sensor 41 is fixed to the inner peripheral surface of the casing 22. Alternatively, humidity sensor 41 may be fixed to a member such as bearing support member 26 disposed inside housings 21 and 22.

Next, the foreign substance detection device 51 includes the gas sensor 44 and the odor sensor 45 as sensors for detecting physical properties of foreign substances. The gas sensor 44 and the odor sensor 45 are sensors that detect gas corresponding to a substance contained in the cutting fluid. In the example shown in fig. 1 and 2, two sensors, i.e., the gas sensor 44 and the odor sensor 45, are disposed, but either sensor may be disposed.

The gas sensor 44 detects a specific gas contained in the air inside the feed shaft motor 31. For example, the cutting fluid may contain a sulfur compound as an extreme pressure additive (extreme pressure additive). At this time, a gas sensor 44 for detecting hydrogen sulfide generated from the sulfur compound is disposed. The gas sensor 44 of the present embodiment detects the concentration of a specific gas.

The odor sensor 45 detects the odor of the air inside the feed shaft motor 31. For example, an organic compound may be added as an additive to the cutting fluid. The additive of an organic compound functions as an extreme pressure additive, and also functions as a surfactant (surfactant) for suppressing rust on a workpiece. Organic compounds give off a characteristic odor. When the additive of the cutting fluid contains a volatile organic compound, an odor sensor 45 for detecting the odor of the organic compound is disposed. The odor sensor 45 of the present embodiment detects the intensity of the odor. The intensity of the odor corresponds to the concentration of the gas. Therefore, the odor sensor 45 can detect the concentration of the specific gas.

As the physical property information of the foreign matter at this time, a determination range of the concentration of the gas related to the cutting fluid can be adopted. The determination range of the gas concentration relating to the cutting fluid is set in advance and stored in the storage unit 3. The determination unit 10 obtains an output of the gas sensor 44 or the odor sensor 45. The determination unit 10 acquires the determination range relating to the cutting fluid from the storage unit 3. The determination unit 10 determines whether or not the gas concentration is within a determination range relating to the cutting fluid, based on the output of the gas sensor 44 or the odor sensor 45. When the gas concentration is within the judgment range relating to the cutting fluid, the judgment unit 10 judges that the cutting fluid enters the feed shaft motor 31.

The determination unit 10 may calculate the gas concentration from the odor intensity detected by the odor sensor 45. Alternatively, when the odor intensity is within a predetermined odor intensity determination range, the gas concentration may be determined to be within the gas concentration determination range.

When it is determined that the cutting fluid has entered the feed shaft motor 31, the display unit 9 displays the entry of the cutting fluid. The display unit 9 may display information on a member that may be deteriorated or broken due to contact with the cutting fluid. For example, when it is determined that the cutting fluid containing a sulfur compound intrudes into the interior of the feed shaft motor 31, the display portion 9 may display that the member formed of rubber may be deteriorated. For example, the display unit 9 may display that an O-ring disposed between the housings 21 and 22 and the stator 12, an O-ring disposed in a portion where the detector is fixed, or the oil seal 20 may be deteriorated.

The gas sensor 44 and the odor sensor 45 may be disposed at any position in the internal space of the feed shaft motor 31, as in the case of the humidity sensor 41. In the example shown in fig. 2, the gas sensor 44 is fixed to the inner peripheral surface of the casing 22. Further, the odor sensor 45 is fixed to the inner peripheral surface of the housing 21.

Next, the foreign substance detection device 51 includes an ion sensor 42 that detects ions corresponding to a substance included in the cutting fluid as a sensor for detecting a physical property of the foreign substance. The cutting fluid may contain a chlorine compound, a sulfur compound, or a phosphorus compound as an additive. For example, these compounds are sometimes contained as extreme pressure additives. As the ion sensor 42, a sensor for detecting corresponding ions such as chlorine compounds, sulfur compounds, or phosphorus compounds can be used. For example, when a chlorine compound is contained in the additive of the cutting fluid, the ion sensor 42 for detecting chlorine ions may be provided. When a sulfur compound is contained in the additive of the cutting fluid, an ion sensor 42 for detecting sulfide ions may be provided. Alternatively, when a compound containing phosphorus is contained in the additive of the cutting fluid, the ion sensor 42 for detecting phosphide ions may be provided.

As the ion sensor 42, a sensor that determines whether or not a specific ion having a predetermined concentration or higher is contained in the liquid can be used. Alternatively, a sensor for detecting the concentration of ions contained in the liquid may be used as the ion sensor 42.

As the physical property information of the foreign matter in these cases, a determination range of the ion concentration relating to the cutting fluid can be adopted. The determination range of the ion concentration of the cutting fluid is set in advance and stored in the storage unit 3. The determination unit 10 acquires an output of the ion sensor 42. The determination unit 10 acquires the determination range of the ion concentration of the cutting fluid from the storage unit 3. The determination unit 10 determines whether or not the ion concentration is within a determination range relating to the cutting fluid, based on the output of the ion sensor 42. When the ion concentration is within the judgment range relating to the cutting fluid, the judgment unit 10 judges that the cutting fluid enters the feed shaft motor 31.

When it is determined that the cutting fluid has entered the feed shaft motor 31, the display unit 9 may display information on the entry of the cutting fluid and information on a member which may be deteriorated or broken due to contact with the cutting fluid. For example, when the ion sensor 42 detects chlorine ions, the display unit 9 may display that the components made of resin disposed inside the feed shaft motor 31 may be deteriorated. For example, the display part 9 may display that an impregnating agent (impregnating agent) formed as a resin wrapping the coil may be deteriorated. Alternatively, when the ion sensor 42 is a sensor that detects sulfide ions, the display portion 9 may display that a component formed of rubber, such as the oil seal 20, may be deteriorated.

The ion sensor 42 may be disposed at any position inside the feed shaft motor 31. However, in order for the ion sensor 42 to detect ions, the liquid needs to be in contact with the ion sensor 42. Therefore, the ion sensor 42 is preferably disposed in the vicinity of the path through which the cutting fluid enters the feed shaft motor 31.

The cutting fluid enters from the joint between the structural members of the feed shaft motor 31. The feed shaft motor 31 includes a plurality of components that isolate the exterior from the interior of the feed shaft motor 31. For example, the housings 21, 22, the stator 12, the rear cover 23, the shaft 13, and the oil seal 20 correspond to components that isolate the inside of the feed shaft motor 31 from the outside. The ion sensor 42 is preferably disposed in the vicinity of a portion where these components contact each other.

For example, as indicated by arrow 82, the cutting fluid enters from a portion of casing 21 in contact with stator 12, or from a portion of casing 22 in contact with stator 12. Alternatively, as indicated by an arrow 83, the cutting fluid enters a space inside the feed shaft motor 31 from a portion of the oil seal 20 that contacts the shaft 13. Therefore, in the example shown in fig. 2, the ion sensor 42 is disposed in the vicinity of the portion where each of the housings 21 and 22 contacts the stator 12. The ion sensor 42 is disposed in the vicinity of a portion where the oil seal 20 contacts the shaft 13. An ion sensor 42 is disposed in a space sandwiched between the oil seal 20 and the bearing 14. With such a configuration, the cutting fluid entering the cutting fluid sensor can easily come into contact with the ion sensor 42, and the cutting fluid can be detected more reliably. In addition to the above-described embodiment, an ion sensor may be disposed in the vicinity of a portion where the rear cover 23 contacts the housing 22.

Next, the foreign matter detection device 51 includes a pH sensor 43 for detecting a pH value as a sensor for detecting a physical property of the foreign matter. The pH sensor 43 may detect the pH of the liquid. As described above, the cutting fluid contains various additives. The pH varies depending on the additive.

As the physical property information of the foreign matter at this time, a determination range of the pH value of the cutting fluid can be used. The determination range of the pH value of the cutting fluid is set in advance and stored in the storage unit 3. The determination unit 10 acquires the output of the pH sensor 43. The determination unit 10 determines whether or not the pH value is within a determination range relating to the cutting fluid, based on the output of the pH sensor 43. When the pH value is within the determination range relating to the cutting fluid, the determination unit 10 determines that the cutting fluid enters the feed shaft motor 31.

When it is determined that the cutting fluid has entered the feed shaft motor 31, the display unit 9 displays information on the entry of the cutting fluid and information on components that may be deteriorated or broken due to contact with the cutting fluid. For example, when the cutting fluid is strongly alkaline, it can be shown that parts formed of aluminum, such as the housings 21, 22, may corrode. Further, the display section 9 may display that a component formed of rubber, such as the oil seal 20, or a component formed of resin may deteriorate.

The pH sensor 43 is required to be in contact with the liquid in order to detect the pH value. Therefore, as with the ion sensor 42, the pH sensor 43 is preferably disposed in the vicinity of a portion where members that isolate the outside and the inside of the feed shaft motor 31 are in contact with each other. In the example shown in fig. 2, the pH sensor 43 is disposed in the vicinity of a portion of the housing 21 that contacts the stator 12, in the vicinity of a portion of the housing 22 that contacts the stator 12, and in the vicinity of a portion of the oil seal 20 that contacts the shaft 13.

In this way, at least one sensor of the humidity sensor 41, the ion sensor 42, the pH sensor 43, the gas sensor 44, and the odor sensor 45 is disposed in the feed shaft motor 31. The determination unit 10 can determine whether or not the cutting fluid has entered the feed shaft motor 31 by comparing the determination range with a predetermined determination range relating to the cutting fluid.

The foreign matter detection device 51 of the present embodiment includes a plurality of sensors for determining the intrusion of the cutting fluid as a specific foreign matter. The plurality of sensors include sensors of different types from each other. In the example shown in fig. 1 and 2, 5 kinds of sensors such as a humidity sensor 41 and an ion sensor 42 are arranged.

Among these plural sensors, 2 or more sensors different in kind from each other may be disposed inside the feed shaft motor 31. The determination unit 10 determines the intrusion of foreign matter and the type of foreign matter with respect to the output of each sensor. For example, the determination unit 10 determines whether or not the cutting fluid enters the cutting fluid based on the output of each sensor. When it is determined that foreign matter has intruded into the output of at least one of the plurality of sensors, the determination unit 10 may determine that foreign matter has intruded into the feed shaft motor 31. By this control, the intrusion of foreign matter can be detected at an early stage. For example, when the humidity sensor 41 is used, it may take time until the humidity rises. In addition, the ion sensor 42 needs to be in contact with the cutting fluid. However, by disposing the humidity sensor 41 and the ion sensor 42 in the feed shaft motor 31, the chance that the intrusion of the cutting fluid can be detected increases, and the intrusion of the cutting fluid can be detected early.

Alternatively, the determination unit 10 may determine that foreign matter has entered the feed shaft motor 31 when it is determined that foreign matter has entered all of the outputs of the plurality of sensors. That is, when it is determined that no foreign matter has entered the output of at least one of the plurality of sensors, the determination unit 10 may finally determine that the cutting fluid has not entered the feed shaft motor 31. For example, it may be determined that the cutting fluid has entered based on the output of the ion sensor 42, while it may be determined that the cutting fluid has not entered based on the output of the humidity sensor 41. In this case, the determination unit 10 may finally determine that the cutting fluid does not enter. By this control, it can be determined that foreign matter has entered only when foreign matter has entered reliably.

Next, an example other than the cutting fluid will be described as foreign matter that enters the feed shaft motor. Fig. 3 is a block diagram of another machine tool according to the present embodiment. Fig. 4 is a schematic cross-sectional view of a feed shaft motor of another machine tool according to the present embodiment. The machine tool 1 shown in fig. 3 has a 2 nd foreign matter detection device 52.

Referring to fig. 3 and 4, the 2 nd foreign matter detection device 52 detects the intrusion of chips or lubricating oil, which are foreign matter, into the feed shaft motor 31. First, determination of chip intrusion will be described. The machine tool 1 may machine a magnetic workpiece. For example, a workpiece made of iron is sometimes machined. The foreign object detection device 52 includes the proximity sensor 46 as a sensor for detecting a physical property of the foreign object. The proximity sensor 46 detects the distance from the proximity sensor 46 to the object. Alternatively, the proximity sensor 46 detects the approach of an object to a predetermined distance. The proximity sensor 46 of the present embodiment detects a magnetic object. That is, the proximity sensor 46 does not detect an object having no magnetism, but detects an object having magnetism. Magnetic chips are generated when a workpiece is machined by the machine tool 1.

As the physical property information of the foreign matter, the operator sets a determination range of the distance related to the chip in advance and inputs the determination range to the storage unit 3. The determination unit 10 acquires the determination range of the distance related to the chip from the storage unit 3. The determination unit 10 also obtains the output of the proximity sensor 46. The determination unit 10 determines whether or not the object approaches within the determination range of the distance based on the output of the proximity sensor 46. When the object approaches within the determination range of the distance, the determination unit 10 determines that the chips enter the feed shaft motor 31. That is, when the proximity sensor 46 detects the approach of the object, the determination unit 10 determines that the chips enter the feed shaft motor 31.

When chips intrude into the feed shaft motor 31, insulation failure of the winding wire or insulation failure of the connector arranged inside the feed shaft motor 31 may occur. Alternatively, when chips enter the components such as the bearings 14 and 15, noise, vibration, and breakage may occur. When the determination unit 10 determines the chip intrusion, the display unit 9 displays the chip intrusion. Further, the display unit 9 can display that there is a possibility that a poor insulation of components in the interior of the feed shaft motor 31, damage of components, abnormal sound, and vibration may occur.

Referring to fig. 4, since the chips have a predetermined size, the chips are less likely to enter from the portions where the casings 21 and 22 contact the stator 12. On the other hand, as indicated by an arrow 83, chips may intrude from a portion of the oil seal 20 that contacts the shaft 13. Therefore, the proximity sensor 46 may be disposed in the vicinity of the portion of the oil seal 20 that contacts the shaft 13. In this way, the proximity sensor 46 may be disposed in the vicinity of a portion where a plurality of components that isolate the outside from the inside of the motor contact each other. For example, the proximity sensor 46 may be disposed in a space between the oil seal 20 and the bearing 14. With this configuration, the intrusion of chips can be determined more accurately.

Next, the judgment of the intrusion of the lubricating oil will be described. The speed reducer may be connected to the shaft 13 of the feed shaft motor 31. A lubricating oil for lubricating the gears is disposed inside the reduction gear. Therefore, the lubricating oil may enter the feed shaft motor 31.

The foreign substance detection device 52 includes an ion sensor 42 and a pH sensor 43 as sensors for detecting physical properties of foreign substances. The ion sensor 42 detects ions corresponding to a substance contained in the lubricating oil. Sometimes extreme pressure additives are included as additives in lubricating oils. Sometimes, lubricating oil extreme pressure additives contain sulfur compounds or chlorine compounds. Therefore, as the ion sensor 42 for detecting the lubricating oil, for example, a sensor for detecting sulfide ions or a sensor for detecting chloride ions can be used.

As the physical property information of the foreign matter, the operator sets a determination range of the ion concentration of the lubricating oil in advance and inputs the determination range to the storage unit 3. The determination unit 10 determines whether or not the ion concentration is within a determination range relating to the lubricating oil, based on the output of the ion sensor 42. When the ion concentration is within the determination range relating to the lubricating oil, the determination unit 10 determines that the lubricating oil has entered the feed shaft motor 31.

Alternatively, as the physical property information of the foreign matter, the operator sets a determination range of the pH value relating to the lubricating oil in advance and inputs the determination range to the storage unit 3. The pH of the lubricating oil varies depending on the additive. The determination unit 10 determines whether or not the pH value is within a determination range relating to the lubricating oil based on the output of the pH sensor 43. When the pH value is within the determination range relating to the lubricating oil, the determination unit 10 determines that the lubricating oil has entered the feed shaft motor 31.

When the lubricating oil contacts with the internal components of the feed shaft motor 31, insulation failure may occur. When it is determined that the lubricant oil has entered the feed shaft motor 31, the display unit 9 may display that a failure in insulation occurs in a component disposed inside the feed shaft motor 31. For example, the display unit 9 may display that a coil or a connector is poorly insulated. Alternatively, an electromagnetic brake may be disposed between the oil seal 20 and the bearing 14. The electromagnetic brake may not be fully operated because the lubricant oil intrudes into the electromagnetic brake and the clutch slips. Therefore, the display portion 9 can display that the electromagnetic brake may not sufficiently operate.

Referring to fig. 4, it is considered that the lubricating oil flows in from the speed reducer connected to the shaft 13. As indicated by an arrow 83, the lubricating oil enters from the portion of the oil seal 20 that contacts the shaft 13. Therefore, the ion sensor 42 for detecting the intrusion of the lubricating oil can be disposed in the vicinity of the portion of the oil seal 20 that contacts the shaft 13. In this way, the ion sensor 42 can be disposed in the vicinity of a portion where a plurality of components that isolate the outside from the inside of the motor contact each other. For example, the ion sensor 42 may be disposed in a space between the oil seal 20 and the bearing 14. The pH sensor 43 may be disposed at the same position as the ion sensor 42. With this configuration, the intrusion of the lubricating oil can be detected more accurately.

However, the determination range of the pH value relating to the cutting fluid, which is the output of the pH sensor 43, and the determination range of the pH value relating to the lubricating oil, which is the output of the pH sensor 43, may differ from each other. In particular, the determination range for the cutting fluid and the determination range for the lubricating oil may not overlap. In this case, the determination unit 10 may determine the intrusion of the cutting fluid and the intrusion of the lubricating oil based on the output of the common pH sensor 43.

As the physical property information of the foreign matter at this time, a determination range of a pH value relating to the cutting fluid and a determination range of a pH value relating to the lubricating oil can be adopted. The determination unit 10 determines whether or not the pH value is within a determination range relating to the cutting fluid, based on the output of the pH sensor 43. The determination unit 10 determines whether or not the pH value is within a determination range relating to the lubricating oil, based on the output of the pH sensor 43. When the pH value is within the determination range relating to the cutting fluid, the determination unit 10 determines that the cutting fluid has entered the feed shaft motor 31. Alternatively, when the pH value is within the determination range relating to the lubricating oil, the determination unit 10 determines that the lubricating oil has entered the feed shaft motor 31.

In this way, for a plurality of kinds of foreign matter, when the determination ranges for the outputs of the 1 kinds of sensors are different from each other, the determination of the plurality of foreign matters can be performed by the common sensor. In the above embodiment, the intrusion of the cutting fluid or the intrusion of the lubricating oil is determined based on the output of the pH sensor, but the present invention is not limited to this embodiment. For example, when the determination range of ions relating to the cutting fluid for the output of the ion sensor and the determination range of ions of the lubricating oil for the output of the ion sensor do not overlap with each other, the intrusion of the cutting fluid or the intrusion of the lubricating oil can be determined from the output of the common ion sensor.

The foreign matter detection devices 51 and 53 of the present embodiment use sensors for detecting physical properties of foreign matter to determine the intrusion of foreign matter and the type of foreign matter. Therefore, the intrusion of the foreign matter can be determined with high accuracy. For example, it is conceivable to dispose a sensor for detecting temperature inside the motor to detect the intrusion of foreign matter. In this case, the determination may not be accurately performed due to the influence of the temperature around the motor, heat generated from the motor, or the like. However, the foreign object detection device of the present embodiment can determine the physical properties of the foreign object, and can determine the intrusion of the foreign object with high accuracy.

In the foreign matter detection devices 51 and 52 of the above embodiments, the humidity sensor 41, the ion sensor 42, the pH sensor 43, the gas sensor 44, the odor sensor 45, and the proximity sensor 46 are disposed, but the present invention is not limited to this configuration. As the sensor disposed inside the motor, any sensor for detecting a physical property of the foreign matter may be disposed.

The control device of the present embodiment is disposed at a position separated from the motor and connected to the motor via a communication line, but is not limited to this form. A part or the whole of the control device may be fixed to the motor.

In the present embodiment, the feed shaft motor is exemplified as the electric motor of the machine tool, but the present invention is not limited to this embodiment. The foreign object detection device according to the present embodiment may be applied to another motor disposed in a machine tool. In particular, since the cutting fluid and the chips are scattered inside the machining chamber of the machine tool, foreign matter is likely to enter the motor. Therefore, the foreign matter detection device according to the present embodiment is preferably applied to an electric motor such as a spindle motor disposed inside a processing chamber.

According to the foreign object detection device of one aspect of the present disclosure, it is possible to detect intrusion of foreign objects into the motor disposed in the machine tool with high accuracy.

The above embodiments may be combined as appropriate. In the drawings, the same or equivalent portions are denoted by the same reference numerals. The above embodiments are examples and do not limit the invention. The embodiments include modifications of the embodiments described in the claims.