Working machinery

Abstract

Identifying the type of coolant used in machine tools. [Solution] A machine tool 100 includes a sensor unit 3 that emits a first transmission wave and a second transmission wave toward the bottom surface of a coolant tank 2 and receives a reflected wave of the first transmission wave and a reflected wave of the second transmission wave, and a discrimination device 4 that discriminates the type of coolant C from measurement results obtained based on the signal strength of the reflected wave of the first transmission wave and the signal strength of the reflected wave of the second transmission wave received by the sensor unit. The discrimination device 4 is configured so that the measurement results obtained when a water-soluble coolant is stored in the coolant tank differ from the measurement results obtained when an oil-based coolant, which has a lower dielectric constant than that of the water-soluble coolant, is stored in the coolant tank.

Description

[Technical Field]

[0001] The present invention relates to a machine tool capable of distinguishing the type of coolant. [Background technology]

[0002] Water-soluble and oil-based coolants are known as coolants used in machine tools. Generally, water-soluble coolants are often used in machine tools, but oil-based coolants may be used, for example, when performing high-load machining. Because oil-based and water-soluble coolants have different properties, it is necessary to prevent oil-based coolants from being supplied to machine tools designed to use water-soluble coolants.

[0003] To address this issue, Patent Document 1 discloses a device that prevents different types of coolant from mixing in machine tools. This device uses a sensor, which is a quality detection means, to detect whether the coolant flowing into a waste liquid tank where used coolant is stored is water-soluble or oil-based. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 7-60600 Summary of the Invention [Problem to be solved by the invention]

[0005] Patent Document 1 discloses that the type of coolant is determined by a quality sensing means, but does not disclose how the quality sensing means specifically determines the type of coolant.

[0006] An object of the present invention is to determine the type of coolant used in a machine tool. [Means for solving the problem]

[0007] The machine tool of the present invention includes a sensor unit that transmits a signal wave toward the coolant and receives the reflected signal, and a discrimination device that discriminates the type of coolant based on the signal received by the sensor unit. The machine tool is configured so that measurement results based on the signal from the sensor unit differ depending on whether the coolant tank contains a water-soluble coolant or an oil-based coolant. The machine tool discriminates the type of coolant based on the measurement results. [Effects of the Invention]

[0008] According to the machine tool of the present invention, it is possible to determine the type of coolant used in the machine tool. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram of a machine tool according to a first embodiment. [Figure 2] FIG. 3 is a diagram illustrating a measurement performed by the sensor unit in the first embodiment when the coolant is a water-soluble coolant. [Figure 3] FIG. 3 is a diagram schematically showing measurement by the sensor unit in the first embodiment when the coolant is an oil-based coolant. [Figure 4] FIG. 4 is a diagram showing measurement results in the case of a water-soluble coolant and an oil-based coolant in the first embodiment. [Figure 5] 10 is a flowchart of a determination process up to the execution of a first abnormality process in a machine tool. [Figure 6] 10 is a flowchart of a determination process up to the execution of a second abnormality process in a machine tool. [Figure 7] 10 is a flowchart of a determination up to the execution of a third abnormality process in a machine tool. [Figure 8] FIG. 10 is a diagram schematically showing measurement by a sensor unit in a machine tool according to a second embodiment when the coolant is a water-soluble coolant. [Figure 9]FIG. 10 is a diagram schematically showing measurement by a sensor unit in a machine tool according to a second embodiment when the coolant is an oil-based coolant. [Figure 10] FIG. 10 is a diagram showing measurement results in the case of a water-soluble coolant and an oil-based coolant in the machine tool of the second embodiment. [Figure 11] FIG. 1 is a top view schematically showing a machine tool. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0011] First Embodiment FIG. 1 is a schematic diagram of a machine tool according to a first embodiment. The machine tool 100 includes a machine tool main body 1 and a coolant tank 2. The coolant tank 2 stores coolant C and supplies it to the machine tool main body 1. The coolant C used by the machine tool main body 1 returns to the coolant tank 2. The machine tool 100 also includes a sensor unit 3 and a discrimination device 4. The sensor unit 3 emits a first transmission wave and a second transmission wave toward the coolant C in the coolant tank 2 and receives the reflected waves. The discrimination device 4 obtains a measurement result based on the signal strength of the received reflected waves. The first transmission wave and the second transmission wave are set so that the measurement result differs depending on whether the coolant stored in the coolant tank 2 is a water-soluble coolant or an oil-based coolant. The discrimination device 4 determines the type of coolant C stored in the coolant tank 2 based on the obtained measurement result. The discrimination device 4 determines the type of coolant when the machine tool main body 1 is powered on. Each component is described in detail below.

[0012] The machine tool body 1 is not particularly limited, but may be, for example, a multi-tasking machine, such as a numerically controlled NC machine tool. The machine tool body 1 is also a machine tool that uses a water-soluble coolant. The machine tool body 1 is configured to spray coolant supplied from a coolant tank 2 into a machining chamber.

[0013] FIG. 11 is a top view schematically showing a machine tool. Note that in FIG. 11, components constituting the machine tool body 1 are omitted as appropriate so that the interior of the machining chamber 11 can be seen. The coolant tank 2 is provided near the machine tool body 1. The coolant tank 2 is L-shaped when viewed from above. The coolant tank 2 includes a primary tank 22 that stores the coolant used in the machine tool body 1, and a secondary tank 23 that stores the coolant in the primary tank that has been purified using a filter or the like. A portion of the primary tank 22 is provided below the machine tool body 1. A portion of the primary tank 22 is provided below the machining chamber 11. The primary tank 22 collects the coolant used in the machining chamber. A chip conveyor 25 that transports chips is provided in the primary tank 22. The chips transported by the chip conveyor 25 are discharged from a chip conveyor outlet 26. The secondary tank 23 is connected to the primary tank 22, and is configured so that the coolant stored in the primary tank 22 flows into it. Coolant from which chips have been removed by a chip conveyor 25 flows into the secondary tank 23. The secondary tank 23 is provided next to the machine tool body 1. The coolant in the secondary tank 23 is supplied to the machine tool body 1 by a pump 24 or the like. The bottom surface of the coolant tank 2 is made of a metal plate. The metal plate is made of, for example, steel.

[0014] The sensor unit 3 includes a first sensor 31 and a second sensor 32. The first sensor 31 and the second sensor 32 are radar sensors. The first sensor 31 and the second sensor 32 are configured to emit high-frequency radar and receive the reflected waves. The first sensor 31 and the second sensor 32 are arranged in close proximity to each other. The first sensor 31 and the second sensor 32 are arranged above the liquid surface of the coolant C stored in the coolant tank 2. The first sensor 31 and the second sensor 32 do not contact the coolant C. In this embodiment, the first sensor 31 and the second sensor 32 are arranged to be located above the coolant stored in the secondary tank 23. However, the first sensor 31 and the second sensor 32 may also be arranged to be located above the coolant stored in the primary tank 22. In short, it is sufficient that the first sensor 31 and the second sensor 32 are arranged in a position where the radar can be irradiated onto the coolant supplied to the machine tool body 1. The first sensor 31 and the second sensor 32 are provided in the secondary tank 23 near the connection with the primary tank 22. The first sensor 31 and the second sensor 32 are provided near the pump 24. The first sensor 31 and the second sensor 32 are attached, for example, to the outer periphery of the coolant tank 2 (secondary tank 23) and emit radar toward the coolant near the outer periphery. However, the first sensor 31 and the second sensor 32 are not limited to being attached to the outer periphery, but may be supported via a support member and disposed above near the center of the coolant tank 2. Line 40 is an extension line of the upper wall surface of the machining chamber 11 on the page, and line 41 is an extension line of the lower wall surface of the machining chamber 11 on the page. Here, the first sensor 31 and the second sensor 32 are disposed within the range sandwiched between lines 40 and 41.

[0015] Referring to FIG. 1 , the first sensor 31 and the second sensor 32 are arranged to emit radar toward the bottom surface of the coolant tank 2. The first sensor 31 and the second sensor 32 are arranged so that the emitting radar is along the vertical direction. The first sensor 31 and the second sensor 32 are arranged next to each other. The first sensor 31 and the second sensor 32 are arranged close to each other. The first sensor 31 and the second sensor 32 emit radar toward substantially the same location on the coolant tank 2. The first sensor 31 and the second sensor 32 are each connected to the machine tool main body 1 by wire or wirelessly. The strength of the signal emitted by each of the first sensor 31 and the second sensor 32 is set by the machine tool main body 1.

[0016] FIG. 2 is a diagram illustrating a measurement performed by the sensor unit in the first embodiment when the coolant is a water-soluble coolant. (A) in the diagram illustrates a measurement performed by the first sensor 31, and (B) in the diagram illustrates a measurement performed by the second sensor 32. Referring to (A), the first sensor 31 functions as a water level sensor that measures the water level of the coolant stored in the coolant tank 2. The first sensor 31 emits a first transmission wave 311 toward the bottom surface 21 of the coolant tank 2. The first transmission wave 311 is a high-frequency millimeter-wave radar of, for example, approximately 60 GHz. The first transmission wave 311 is reflected by the liquid surface of the water-soluble coolant C1. A first liquid surface reflected wave 312, which is a reflected wave of the first transmission wave 311, travels toward the first sensor 31, and the first sensor 31 receives the first liquid surface reflected wave 312. The first sensor 31 transmits information about the signal strength of the received first liquid surface reflected wave 312 to the discriminator 4.

[0017] Here, the relative dielectric constant of the water-soluble coolant C1 is approximately 70. Therefore, the reflection coefficient at the liquid surface is high, and the first transmission wave 311 is reflected as a first liquid surface reflected wave 312 with a strong signal intensity. In other words, the first liquid surface reflected wave 312 maintains a signal intensity close to that of the first transmission wave 311. Note that a portion of the first transmission wave 311 is not reflected at the liquid surface but passes through the water-soluble coolant C1. A portion of the first transmission wave 311 that passes through the water-soluble coolant C1 is reflected by the bottom surface 21 of the coolant tank 2, and the first sensor 31 receives this reflected wave. However, the machine tool of this embodiment is configured to ignore the reflected wave of the first transmission wave 311 reflected by the bottom surface 21 (hereinafter referred to as the first bottom surface reflected wave). Specifically, in the discrimination device described below, the reception time (distance from the first sensor to the reflection position) of the first liquid surface reflected wave 312, which is a reflected wave reflected at the liquid surface, and the reception time (distance from the first sensor to the reflection position) of the first bottom reflected wave that passes through the water-soluble coolant C1 and is reflected at the bottom surface, are used to determine whether the received reflected wave is the first liquid surface reflected wave 312, and the first bottom reflected wave that is reflected at the bottom surface is excluded from the calculation processing.

[0018] Referring to (B), the second sensor 32 emits a second transmission wave 321 toward the bottom surface 21 of the coolant tank 2. The second transmission wave 321 is a high-frequency millimeter-wave radar of, for example, approximately 60 GHz, similar to the first transmission wave 311. However, the signal strength of the second transmission wave 321 is weaker than that of the first transmission wave 311. The signal strength of the second transmission wave 321 is set to be weaker than that of the first transmission wave 311, for example, by adjusting the gain of the second sensor 32. The second transmission wave 321 is reflected by the liquid surface of the water-soluble coolant C1. A second liquid surface reflected wave 322, which is a reflected wave of the second transmission wave 321, travels toward the second sensor 32, and the second sensor 32 receives the second liquid surface reflected wave 322. Similar to the first transmission wave 311, the second transmission wave 321 is reflected as the second liquid surface reflected wave 322 with a strong signal strength. That is, the second liquid surface reflected wave 322 maintains a signal strength close to that of the second transmitted wave 321. The second sensor 32 transmits information on the signal strength of the received second liquid surface reflected wave 322 to the discrimination device 4. Note that, similar to the first transmitted wave 311, a reflected wave of the second transmitted wave 321 reflected by the bottom surface (hereinafter referred to as a second bottom surface reflected wave) is excluded from the calculation process.

[0019] The discriminator 4 obtains measurement results for each of the signal strength of the first liquid surface reflected wave 312 and the signal strength of the second liquid surface reflected wave 322. Specifically, the discriminator 4 has a preset threshold value for the signal strength. The discriminator 4 compares each of the signal strength of the first liquid surface reflected wave 312 and the signal strength of the second liquid surface reflected wave 322 with the threshold value. The discriminator 4 determines whether each of the signal strength of the first liquid surface reflected wave 312 and the signal strength of the second liquid surface reflected wave 322 is equal to or greater than the threshold value or less than the threshold value.

[0020] Here, when the coolant is a water-soluble coolant C1, the signal strength of the first liquid surface reflected wave 312 and the signal strength of the second liquid surface reflected wave 322 are both equal to or greater than the threshold value. That is, in the first sensor 31 and the second sensor 32, the signal strength of the first transmitted wave 311 and the signal strength of the second transmitted wave 321 are set in advance so that the signal strength of the first liquid surface reflected wave 312 and the signal strength of the second liquid surface reflected wave 322 both exceed the threshold value. Next, the case of an oil-based coolant will be described.

[0021] FIG. 3 is a diagram illustrating a measurement performed by the sensor unit when the coolant is an oil-based coolant in the first embodiment. (A) in the diagram illustrates a measurement performed by the first sensor 31, and (B) in the diagram illustrates a measurement performed by the second sensor 32. Referring to (A), the first sensor 31 emits a first transmission wave 311 toward the bottom surface 21 of the coolant tank 2 and receives a first liquid surface reflected wave 312, similar to the case of the water-soluble coolant described above. The first transmission wave 311 when the coolant is an oil-based coolant has the same signal strength as the first transmission wave when the coolant is a water-soluble coolant. Referring to (B), the second sensor 32 emits a second transmission wave 321 toward the bottom surface 21 of the coolant tank 2 and receives a second liquid surface reflected wave 322, similar to the case of the water-soluble coolant described above. The second transmission wave 321 when the coolant is an oil-based coolant has the same signal strength as the second transmission wave when the coolant is a water-soluble coolant. Therefore, even when the coolant is an oil-based coolant, the signal strength of the second transmission wave 321 is set to be weaker than that of the first transmission wave 311.

[0022] Here, the relative dielectric constant of the oil-based coolant C2 is approximately 2, which is lower than that of the water-soluble coolant C1. Therefore, the reflection coefficient at the liquid surface is lower than that of the water-soluble coolant C1, and the first transmitted wave 311 and the second transmitted wave 321 are reflected as the first liquid surface reflected wave 312 and the second liquid surface reflected wave 322, respectively, with weaker signal strength than in the case of the water-soluble coolant C1. In other words, when the coolant is an oil-based coolant, the first liquid surface reflected wave 312 and the second liquid surface reflected wave 322 each have attenuated signal strength compared to the case of the water-soluble coolant.

[0023] As in the case of the water-soluble coolant described above, the discriminator 4 obtains measurement results for each of the signal strength of the first liquid surface reflected wave 312 and the signal strength of the second liquid surface reflected wave 322. That is, the discriminator 4 determines whether each of the signal strength of the first liquid surface reflected wave 312 and the signal strength of the second liquid surface reflected wave 322 is equal to or greater than a threshold value or less than a threshold value.

[0024] When the coolant is oil-based coolant C2, the first liquid surface reflected wave 312 is equal to or greater than the threshold value, and the second liquid surface reflected wave 322 is less than the threshold value. That is, in the first sensor 31 and the second sensor 32, the signal strength of the first transmission wave 311 and the signal strength of the second transmission wave 321 are set in advance so that the signal strength of the first liquid surface reflected wave 312 is equal to or greater than the threshold value, and the signal strength of the second liquid surface reflected wave 322 is less than the threshold value.

[0025] 4 is a diagram showing the measurement results for a water-soluble coolant and an oil-based coolant in the first embodiment. As described above, when the coolant is a water-soluble coolant, the signal strength of the first liquid surface reflected wave 312 and the signal strength of the second liquid surface reflected wave 322 received by the sensor unit 3 are both equal to or greater than the threshold value. When the signal strength of the reflected wave is equal to or greater than the threshold value, the discriminator 4 judges it as "OK." Therefore, when the coolant is a water-soluble coolant, the measurement result is "OK-OK," as shown in the figure.

[0026] On the other hand, if the coolant is oil-based, the signal strength of the first liquid surface reflected wave 312 received by the sensor unit 3 will be equal to or greater than the threshold, but the signal strength of the second liquid surface reflected wave 322 will be less than the threshold. If the signal strength of the reflected wave is less than the threshold, the discriminator 4 will judge it as "NG." Therefore, if the coolant is oil-based, the measurement result will be "OK-NG" as shown in the figure, which is different from the measurement result for water-soluble coolant.

[0027] If the measurement result is "OK-OK", the discrimination device 4 determines that the coolant stored in the coolant tank 2 is a water-soluble coolant. If the measurement result is "OK-NG", the discrimination device 4 determines that the coolant stored in the coolant tank 2 is an oil-based coolant.

[0028] In this way, in machine tool 100, sensor unit 3 emits two transmission waves with different signal intensities toward the coolant stored in the coolant tank. The signal intensities of first transmission wave 311 and second transmission wave 321 are set so that the measurement results based on the first liquid surface reflected wave and second liquid surface reflected wave, respectively, differ between water-soluble coolant and oil-based coolant. Therefore, machine tool 100 can identify the type of coolant used in machine tool main body 1.

[0029] Furthermore, in machine tool 100, first sensor 31 functions as a water level sensor. Therefore, machine tool 100 can measure the water level of the coolant in addition to determining the type of coolant.

[0030] <Modification> If machine tool 100 determines that the coolant stored in coolant tank 2 is water-soluble coolant, machine tool 100 may instruct machine tool main body 1 to machine a workpiece in accordance with a predetermined machining program. On the other hand, if machine tool 100 determines that the coolant stored in coolant tank 2 is oil-based coolant, machine tool 100 may instruct machine tool main body 1 to execute at least one of the following various abnormality processes. The various abnormality processes will be described below.

[0031] 5 is a flowchart of the determination up to the execution of the first abnormality processing in the machine tool. First, the determination device 4 in the machine tool 100 determines the type of coolant stored in the coolant tank 2 (step S11).

[0032] If the discrimination device 4 determines that the coolant stored in the coolant tank 2 is a water-soluble coolant (YES in step S11), it permits the machine tool body 1 to machine the workpiece (step S15). If the discrimination device 4 determines that the coolant stored in the coolant tank 2 is an oil-based coolant (NO in step S11), it discriminates whether the machine tool body 1 is a machine tool with water-soluble coolant specifications or an oil-based coolant specifications (step S12).

[0033] Machine tools that use oil-based coolant are equipped with fire protection equipment. The fire protection equipment is, for example, an automatic fire extinguishing device. On the other hand, machine tools that use water-soluble coolant are generally not equipped with fire protection equipment, but may be equipped with fire protection equipment as an individual specification. Information regarding the specifications of the machine tool is stored, for example, in a memory installed in the machine tool. The discrimination device 4 communicates with the machine tool main body 1 wirelessly or via a cable. The discrimination device 4 acquires information regarding the specifications of the machine tool main body by communicating with the machine tool main body 1. Note that the order of execution of steps S11 and S12 may be reversed, or they may be executed simultaneously. Furthermore, the discrimination device 4 may have information regarding the specifications of the machine tool main body 1 in advance. In this case, step S12 is omitted.

[0034] When the discrimination device 4 determines that the machine tool main body 1 is a machine tool with oil-based coolant specifications (YES in step S12), it permits the machine tool main body 1 to machine a workpiece (step S15). When the discrimination device 4 determines that the machine tool main body 1 is a machine tool with water-soluble coolant specifications (NO in step S12), it determines whether the machine tool main body 1 is equipped with an automatic fire extinguishing device (step S13). The automatic fire extinguishing device supplies, for example, water mist, fire extinguishing agent, carbon dioxide, etc. into the machining chamber. Information regarding the presence or absence of an automatic fire extinguishing device is stored, for example, in a memory installed in the machine tool main body 1. The discrimination device 4 obtains information regarding the presence or absence of an automatic fire extinguishing device by communicating with the machine tool main body 1. Note that the discrimination device 4 may have information regarding the presence or absence of an automatic fire extinguishing device in advance. In this case, step S13 is omitted.

[0035] If the discrimination device 4 determines that the machine tool body 1 is equipped with an automatic fire extinguishing device (YES in step S13), it permits the machine tool body 1 to process the workpiece (step S15). If the discrimination device 4 determines that the machine tool body 1 is not equipped with an automatic fire extinguishing device (NO in step S13), it instructs the machine tool body 1 to execute first abnormality processing (step S14).

[0036] The first abnormality processing is a warning display. When the machine tool main body 1 receives an instruction to execute the first abnormality processing from the discrimination device 4, it displays a warning on a panel of the operation panel. The machine tool main body 1 may also turn on a warning light. The warning display is not limited to this, and is executed to notify people in the vicinity of the abnormality.

[0037] The first abnormality processing may be to execute interlock control in addition to or instead of displaying a warning. When the machine tool body 1 receives an instruction to execute interlock control from the discrimination device 4, it stops execution of the machining program.

[0038] By having the machine tool execute the first abnormality processing in this way, it is possible to notify people around the machine tool body 1 that an oil-based coolant is being used or is being used in the machine tool body 1 that is designed for water-soluble coolant. Furthermore, by executing interlock control, the start of machining using oil-based coolant is prevented even if oil-based coolant is stored in the coolant tank.

[0039] 6 is a flowchart of the determination up to the execution of the second abnormality processing in the machine tool. First, the determination device 4 determines the type of coolant stored in the coolant tank 2 (step S21).

[0040] When the discrimination device 4 determines that the coolant stored in the coolant tank 2 is a water-soluble coolant (YES in step S21), it permits the machine tool body 1 to machine the workpiece (step S24). When the discrimination device 4 determines that the coolant stored in the coolant tank 2 is an oil-based coolant (NO in step S21), it discriminates whether the machine tool body 1 is a machine tool with a water-soluble coolant specification or a machine tool with an oil-based coolant specification (step S22). Note that the order of execution of steps S21 and S22 may be reversed, or they may be executed simultaneously. Furthermore, the discrimination device 4 may have information regarding the specifications of the machine tool body in advance. In this case, step S22 is omitted.

[0041] If the discrimination device 4 determines that the machine tool body 1 is a machine tool with oil-based coolant specifications (YES in step S22), it permits the machine tool body 1 to process the workpiece (step S24). If the discrimination device 4 determines that the machine tool body 1 is a machine tool with water-soluble coolant specifications (NO in step S22), it instructs the machine tool body 1 to execute second abnormality processing (step S23).

[0042] The second abnormality processing is a processing for suppressing unmanned operation of the machine tool main body 1. When the machine tool main body 1 receives an instruction to execute the second abnormality processing from the discrimination device 4, it stops the machining program at regular time intervals and restarts the machining program that has been stopped by an input operation by the operator. The input operation by the operator is, for example, pressing a button on the control panel.

[0043] By having the machine tool execute the second abnormality processing in this way, even if oil-based coolant is being used or has been used in a machine tool body 1 that is designed for water-soluble coolant, machining is prevented from being started or continued without an operator being around the machine tool body 1.

[0044] 7 is a flowchart of the determination up to the execution of the third abnormality process in the machine tool. First, the determination device 4 determines the type of coolant stored in the coolant tank 2 (step S31).

[0045] When the discrimination device 4 determines that the coolant stored in the coolant tank 2 is a water-soluble coolant (YES in step S31), it permits the machine tool body 1 to machine the workpiece (step S34). When the discrimination device 4 determines that the coolant stored in the coolant tank 2 is an oil-based coolant (NO in step S31), it discriminates whether the machine tool body 1 is a machine tool with a water-soluble coolant specification or a machine tool with an oil-based coolant specification (step S32). Note that the execution order of steps S31 and S32 may be reversed, or they may be performed simultaneously. Furthermore, the discrimination device 4 may have information regarding the specifications of the machine tool body in advance. In this case, step S32 is omitted.

[0046] If the discrimination device 4 determines that the machine tool body 1 is a machine tool with oil-based coolant specifications (YES in step S32), it permits the machine tool body 1 to process the workpiece (step S34). If the discrimination device 4 determines that the machine tool body 1 is a machine tool with water-soluble coolant specifications (NO in step S32), it instructs the machine tool body 1 to execute a third abnormality process (step S33).

[0047] The third abnormality processing is a processing for reducing the machining load. When the machine tool main body 1 receives an instruction to execute the third abnormality processing from the discrimination device 4, it monitors the load on the spindle. The spindle here refers to the spindle that holds the tool in a machining center, the spindle that holds the workpiece in a turning center, and the spindle that holds the tool and / or the spindle that holds the workpiece in a multi-tasking machine. The machine tool main body 1 changes the load on the spindle that it is monitoring to a limit value that is lower than the normal value. The normal value of the load is a value that is set in advance. The normal value of the load is set as appropriate depending on the type of workpiece, the type of tool used, the machining conditions, etc.

[0048] By having the machine tool execute the third abnormality processing in this way, proper machining can be performed even if oil-based coolant is or has been used in a machine tool body 1 designed for water-soluble coolant.

[0049] Second Embodiment In the machine tool of the first embodiment described above, a configuration in which the signal strengths of the first transmission wave and the second transmission wave emitted by the sensor unit are different has been described. In the machine tool of the second embodiment, a configuration in which the signal strengths of the first transmission wave and the second transmission wave are the same will be described. In the following description, configurations similar to those of the first embodiment will be omitted as appropriate.

[0050] 8 is a diagram illustrating a measurement performed by the sensor unit in the machine tool according to the second embodiment when the coolant is a water-soluble coolant. (A) in the diagram illustrates a measurement performed by the first sensor 31, and (B) in the diagram illustrates a measurement performed by the second sensor 32. Referring to (A), the sensor unit 3 includes the first sensor 31 and the second sensor 32, both of which are radar sensors.

[0051] The first sensor 31 emits a first transmission wave 311 toward the bottom surface 21 of the coolant tank 2 and receives a first liquid surface reflected wave 312 reflected by the liquid surface of the water-soluble coolant C1. The first sensor 31 transmits information about the signal strength of the received first liquid surface reflected wave 312 to the discrimination device 4. Here, a portion of the first transmission wave 311 (indicated by the dashed downward arrow in the figure) is not reflected by the liquid surface, passes through the water-soluble coolant C1, and is reflected by the bottom surface 21 of the coolant tank 2. The first sensor 31 receives a first bottom reflected wave reflected by the bottom surface 21. The first sensor 31 transmits information about the signal strength of the received first bottom reflected wave 313 to the discrimination device 4.

[0052] The discrimination device 4 uses the signal intensity information of the first liquid surface reflected wave 312, not the first bottom surface reflected wave 313, in the coolant discrimination process. Therefore, the discrimination device 4 executes a masking process M1. For example, assume that the height of the coolant tank 2 is 300 mm and the liquid surface height of the water-soluble coolant C1 is 250 mm. The discrimination device 4 is preset to exclude reflected waves reflected within a height range of 30 mm from the bottom surface 21 of the coolant tank 2 from the coolant discrimination process. In other words, the discrimination device 4 is configured not to use the signal intensity information of the first bottom surface reflected wave 313 in the coolant discrimination process. If the coolant is a water-soluble coolant, the discrimination device 4 is configured to use the signal intensity information of the first liquid surface reflected wave 312 in the coolant discrimination process.

[0053] The method of masking performed by the discriminator 4 is not particularly limited. For example, the discriminator 4 discriminates between the first liquid surface reflected wave 312 and the first bottom surface reflected wave 313 based on the reception time of the received reflected wave (the distance from the first sensor to the reflection position). The discriminator 4 performs masking on the discriminated first bottom surface reflected wave 313. Alternatively, for example, in the case of the water-soluble coolant C1, the signal strength of the first liquid surface reflected wave 312 reflected from the liquid surface is stronger than the first bottom surface reflected wave 313 reflected from the bottom surface 21. Therefore, the discriminator 4 may discriminate between the first liquid surface reflected wave 312 and the first bottom surface reflected wave 313 based on the signal strength of the received reflected wave.

[0054] Referring to (B), the second sensor 32 emits a second transmission wave 321 toward the bottom surface 21 of the coolant tank 2. The signal strength of the second transmission wave 321 is the same as that of the first transmission wave 311. The second sensor 32 receives a second liquid surface reflected wave 322, which is a wave of the second transmission wave 321 reflected by the liquid surface of the water-soluble coolant C1. The second sensor 32 transmits information on the signal strength of the received second liquid surface reflected wave 322 to the discrimination device 4.

[0055] A portion of the second transmission wave 321 (indicated by the dashed downward arrow in the figure) is not reflected by the liquid surface, but passes through the water-soluble coolant C1 and is reflected by the bottom surface 21 of the coolant tank 2. The second sensor 32, like the first sensor 31, receives the second bottom-surface reflected wave reflected by the bottom surface 21. The first sensor 31 transmits information on the signal intensity of the received second bottom-surface reflected wave 323 to the discrimination device 4.

[0056] The discrimination device 4 performs a different process on the signal received from the second sensor 32 than on the signal received from the first sensor 31. That is, the discrimination device 4 performs a mask process on the signal received from the first sensor 31 to remove the first bottom reflected wave 313 reflected by the bottom surface 21 of the coolant tank 2. On the other hand, the discrimination device 4 does not remove the second bottom reflected wave 323 reflected by the bottom surface 21 of the coolant tank 2 from the signal received from the second sensor 32.

[0057] However, when receiving multiple reflected waves, the discriminator 4 is configured to use the reflected wave with the strongest signal strength for the coolant discrimination process. That is, the discriminator 4 is configured to use one reflected wave for the coolant discrimination process. The discriminator 4 receives both information on the signal strength of the second liquid surface reflected wave 322 and information on the signal strength of the second bottom reflected wave 323 from the second sensor 32. The discriminator 4 compares the signal strength of the received second liquid surface reflected wave 322 with the signal strength of the second bottom reflected wave 323. If the coolant is the water-soluble coolant C1, the signal strength of the second liquid surface reflected wave 322 is stronger than the signal strength of the second bottom reflected wave 323. Therefore, the discriminator 4 receives information on the signal strength of the second liquid surface reflected wave 322 and information on the signal strength of the second bottom reflected wave 323, but is configured to use the signal strength information of the second liquid surface reflected wave 322 for the coolant discrimination process.

[0058] If the same product as the first sensor 31 is used as the second sensor 32, the discrimination device 4 can also set masking for the second sensor 32, just as it does for the first sensor 31. Let's assume that the bottom surface of the coolant tank 2 is set as the zero point, and the height of the coolant tank 2 is +300 mm. In this case, the discrimination device 4 is set in advance to exclude reflected waves reflected within a height range of -100 mm from the bottom surface 21 (zero point) of the coolant tank 2 from the coolant discrimination process. That is, the discrimination device 4 sets a virtual area outside the coolant tank 2 and performs masking for that area. This sets the discrimination device 4 so as not to ignore (not to mask) reflected waves reflected within the coolant tank 2, particularly the second bottom surface reflected wave 323.

[0059] The discriminator 4 obtains measurement results for the signal strength of the first liquid surface reflected wave 312 and the signal strength of the second liquid surface reflected wave 322. The discriminator 4 determines whether the signal strength of the first liquid surface reflected wave 312 and the signal strength of the second liquid surface reflected wave 322 are equal to or greater than a threshold value or less than a threshold value. This threshold value differs from the threshold value in the first embodiment and is a value used by the discriminator to determine whether the first sensor 31 and the second sensor 32 have received each reflected wave. That is, when the coolant is the water-soluble coolant C1, the discriminator 4 recognizes the signal strength of the first liquid surface reflected wave 312 and the second liquid surface reflected wave 322. That is, the discriminator 4 determines, as a measurement result, that both the first sensor 31 and the second sensor 32 have detected the liquid level of the water-soluble coolant C1. Next, the case of an oil-based coolant will be described.

[0060] 9 is a diagram schematically illustrating measurement by the sensor unit in the machine tool of the second embodiment when the coolant is an oil-based coolant. (A) in the figure shows measurement by the first sensor 31, and (B) in the figure shows measurement by the second sensor 32. Referring to (A), the first sensor 31 emits a first transmission wave 311 toward the bottom surface 21 of the coolant tank 2 and receives a first liquid surface reflected wave 312 reflected by the liquid surface of the water-soluble coolant C1. The first sensor 31 transmits information on the signal strength of the received first liquid surface reflected wave 312 to the discrimination device 4. The first sensor 31 also receives a first bottom surface reflected wave 313 reflected by the bottom surface 21 of the coolant tank 2. The first sensor 31 transmits information on the signal strength of the received first bottom surface reflected wave 313 to the discrimination device 4.

[0061] As in the case of the water-soluble coolant C1 described above, the discriminator 4 performs a masking process M1 so as not to use the information on the signal intensity of the first bottom surface reflected wave 313 in the coolant discrimination process. When the coolant is the water-soluble coolant C1, the discriminator 4 is configured to use the information on the signal intensity of the first liquid surface reflected wave 312 in the coolant discrimination process.

[0062] Referring to (B), the second sensor 32 emits a second transmission wave 321 toward the bottom surface 21 of the coolant tank 2. The signal strength of the second transmission wave 321 is the same as that of the first transmission wave 311. The second sensor 32 receives a second liquid surface reflected wave 322, which is a wave of the second transmission wave 321 reflected by the liquid surface of the oil-based coolant C2. The second sensor 32 transmits information on the signal strength of the received second liquid surface reflected wave 322 to the discrimination device 4. The second sensor 32 also receives a second bottom surface reflected wave 323 reflected by the bottom surface 21 of the coolant tank 2. The second sensor 32 transmits information on the signal strength of the received second bottom surface reflected wave 323 to the discrimination device 4.

[0063] As in the case of the water-soluble coolant described above, the discrimination device 4 does not perform masking on the second bottom reflected wave 323. Furthermore, when receiving multiple reflected waves, the discrimination device 4 is configured to use the reflected wave with the strongest signal strength for the coolant discrimination process. The discrimination device 4 compares the signal strength of the received second liquid surface reflected wave 322 with the signal strength of the second bottom reflected wave 323. If the coolant is oil-based coolant C2, the signal strength of the second bottom reflected wave 323 is stronger than the signal strength of the second liquid surface reflected wave 322. Therefore, the discrimination device 4 is configured to use information on the signal strength of the received second bottom reflected wave 323 for the coolant discrimination process.

[0064] The discriminator 4 obtains measurement results of the signal intensity of the first liquid surface reflected wave 312 and the signal intensity of the second bottom reflected wave 323. The discriminator 4 determines whether the signal intensity of the first liquid surface reflected wave 312 and the signal intensity of the second bottom reflected wave 323 are equal to or greater than a threshold value or less than a threshold value. This threshold value differs from the threshold value in the first embodiment and is a value used by the discriminator to determine whether the first sensor 31 and the second sensor 32 have received each reflected wave. That is, if the coolant is the oil-based coolant C2, the discriminator 4 recognizes the signal intensity of the first liquid surface reflected wave 312 and the second bottom reflected wave 323. That is, the discriminator 4 determines, as a measurement result, that the first sensor 31 has detected the liquid surface of the oil-based coolant C2 and the second sensor 32 has detected the bottom surface of the oil-based coolant C2 (the bottom surface 21 of the coolant tank 2).

[0065] 10 is a diagram showing measurement results for a water-soluble coolant and an oil-based coolant in the machine tool of the second embodiment. When the coolant is a water-soluble coolant, the discrimination device 4 uses a first liquid surface reflected wave 312 reflected by the liquid surface of the water-soluble coolant in the discrimination process of the signal received from the first sensor 31, and removes a first bottom reflected wave 313 from the bottom surface 21 of the coolant tank 2 by masking. Therefore, the discrimination device 4 recognizes the liquid level of the water-soluble coolant C1 based on the signal received from the first sensor 31 (the signal strength of the first liquid surface reflected wave 312).

[0066] The discrimination device 4 is configured to perform masking outside the coolant tank for the signal received from the second sensor 32. Therefore, when the coolant is a water-soluble coolant, the discrimination device 4 receives from the second sensor 32 a second liquid surface reflected wave 322 reflected by the liquid surface of the water-soluble coolant and a second bottom reflected wave from the bottom surface 21 of the coolant tank 2. However, the discrimination device 4 uses the second liquid surface reflected wave 322 or the second bottom reflected wave, whichever has the stronger signal strength, i.e., the second liquid surface reflected wave 322, for the coolant discrimination process. Therefore, when the coolant is a water-soluble coolant, the measurement result will be "liquid level" for the first sensor 31 and "liquid level" for the second sensor 32, as shown in the figure.

[0067] When the coolant is an oil-based coolant, the discrimination device 4 uses a first liquid surface reflected wave 312 reflected by the liquid surface of the oil-based coolant in the discrimination process of the signal received from the first sensor 31, and removes the first bottom reflected wave from the bottom surface 21 of the coolant tank 2 by masking. Therefore, the discrimination device 4 recognizes the liquid level of the oil-based coolant C2 based on the signal received from the first sensor 31 (the signal strength of the first liquid surface reflected wave 312).

[0068] The discrimination device 4 is configured to perform masking outside the coolant tank for the signal received from the second sensor 32. Therefore, when the coolant is an oil-based coolant, the discrimination device 4 receives from the second sensor 32 a second liquid surface reflected wave 322 reflected by the liquid surface of the oil-based coolant and a second bottom reflected wave 323 from the bottom surface 21 of the coolant tank 2. However, the discrimination device 4 uses the second liquid surface reflected wave 322 or the second bottom reflected wave, whichever has the stronger signal strength, i.e., the second bottom reflected wave 323, for the coolant discrimination process. Therefore, when the coolant is an oil-based coolant, the measurement results for the first sensor 31 are "liquid surface" and for the second sensor 32 are "tank bottom," as shown in the figure.

[0069] If the measurement result is "liquid level - liquid level", the discrimination device 4 determines that the coolant stored in the coolant tank 2 is a water-soluble coolant. If the measurement result is "liquid level - tank bottom", the discrimination device 4 determines that the coolant stored in the coolant tank 2 is an oil-based coolant.

[0070] As described above, in the machine tool of the second embodiment, the sensor unit 3 emits two transmission waves with the same signal strength toward the coolant stored in the coolant tank. The discrimination device 4 is configured to detect the coolant level based on information about the reflected wave received from the first sensor 31. The discrimination device 4 is configured to detect the liquid level in the case of a water-soluble coolant, or the bottom surface 21 of the coolant tank 2 in the case of an oil-based coolant, based on information about the reflected wave received from the second sensor 32. Therefore, the machine tool 100 can discriminate the type of coolant used in the machine tool body 1.

[0071] It should be noted that the machine tool of the second embodiment can also execute the various abnormality processes described in the modified example of the first embodiment.

[0072] The above-described embodiments are illustrative in all respects and are not limiting. Modifications and variations are possible for those skilled in the art. The scope of the present invention is defined not by the above-described embodiments but by the claims. Furthermore, the scope of the present invention includes modifications from the embodiments within the scope of the claims and their equivalents.

[0073] For example, in the first and second embodiments, the sensor unit 3 has been described as including two sensors, the first sensor 31 and the second sensor 32. However, the sensor unit 3 may have only one sensor. In this case, the one sensor has the functions of both the first sensor 31 and the second sensor 32. For example, the one sensor may first function as the first sensor 31, and after measurement as the first sensor 31 is completed, the one sensor may function as the second sensor 32. The one sensor may function as the second sensor 32, and then as the first sensor 31.

[0074] For example, in the first and second embodiments, a configuration has been described in which the discrimination device 4 is included in the machine tool main body 1. However, the discrimination device 4 does not have to be included in the machine tool main body 1. The discrimination device 4 may be included in the sensor unit 3. The discrimination device 4 may be provided separately from the machine tool main body 1 and the sensor unit 3.

[0075] For example, in the first and second embodiments, the first sensor 31 and the second sensor 32 are described as radar sensors. However, the first sensor 31 and the second sensor 32 are not limited to this. The first sensor and the second sensor may be, for example, a guide pulse sensor, an ultrasonic sensor, an electromagnetic wave sensor, a laser light sensor, a microwave sensor, or the like. In short, the first sensor and the second sensor may be sensors that utilize the properties of waves. The first sensor may be the same type of sensor as the second sensor, or may be a different type of sensor.

[0076] For example, in the first and second embodiments, the first sensor 31 is described as functioning as a water level sensor. However, the first sensor 31 does not have to function as a water level sensor. The first sensor 31 may be a sensor provided separately from the water level sensor.

[0077] For example, the signal strength of the first sensor 31 and the second sensor 32 in the first embodiment and the masking process of the first sensor 31 and the second sensor 32 in the second embodiment have been described as being configured to be set in the machine tool main body 1. However, these settings are not limited to being configured to be set in the machine tool main body 1. For example, when the discrimination device 4 is mounted on the sensor unit 3, these settings are configured in the sensor unit 3.

[0078] For example, in the first and second embodiments, the machine tool determines the type of coolant when the machine tool main body 1 is powered on. However, the machine tool is not limited to this. The machine tool may determine the type of coolant at any timing.

[0079] For example, in the first and second embodiments, a configuration has been described in which the coolant tank 2 stores a water-soluble coolant C1 or an oil-based coolant C2. However, the coolant tank 2 does not have to store either coolant. That is, the coolant tank 2 may be empty. In this case, the measurement result in the first embodiment will be "NG-NG," and in the second embodiment will be "tank bottom-tank bottom." Therefore, in both the first and second embodiments, it is possible to determine not only the type of coolant stored in the coolant tank 2, but also whether the coolant tank 2 is empty. [Explanation of symbols]

[0080] 100: Machine tools 1: Machine tool body 2: Coolant tank 21: Bottom 3: Sensor unit 31: First sensor 311: First transmission wave 312: 1st liquid surface reflected wave 313: 1st bottom reflected wave 32: Second sensor 321: Second transmission wave 322: Second liquid surface reflected wave 323: 2nd bottom reflected wave 4: Discrimination device C: Coolant C1: Water-soluble coolant C2: Oil-based coolant

Claims

1. A machine tool capable of machining while supplying coolant, The craft club, where crafts are done, a tank that stores the coolant to be supplied to the machining unit, recovers the coolant that has been supplied to the machining unit, and circulates the coolant between the machining unit and the tank, the tank including a filter through which the coolant that has flowed in from the machining unit passes, and the coolant that has passed through the filter is supplied to the machining unit; a sensor that senses the coolant downstream of the filter in the flow direction of the coolant when there is coolant in the tank, to determine whether the coolant is a water-soluble coolant or an oil-based coolant.

2. A machine tool that can perform machining while supplying coolant, The craft club, where crafts are done, a tank containing a coolant for supplying the coolant to the machining part; a sensor that senses the coolant when the coolant is present in the tank in order to determine whether the coolant is a water-soluble coolant or an oil-based coolant; The tank is a primary tank in which the coolant supplied to the machining unit is stored; a secondary tank connected to the primary tank and into which the coolant from the primary tank flows, The sensor senses the coolant stored in the secondary tank.

3. A machine tool that determines the type of coolant stored in a coolant tank, a sensor unit that emits a first transmission wave and a second transmission wave toward a bottom surface of the coolant tank and receives a reflected wave of the first transmission wave and a reflected wave of the second transmission wave; a discrimination device that discriminates the type of coolant from a measurement result obtained based on the signal strength of the reflected wave of the first transmission wave and the signal strength of the reflected wave of the second transmission wave received by the sensor unit, The discrimination device is The measurement result when a water-soluble coolant is stored in the coolant tank is different from the measurement result when an oil-based coolant having a lower dielectric constant than the water-soluble coolant is stored in the coolant tank. When a water-soluble coolant is stored in the coolant tank, the measurement result is obtained based on the signal strength of a first liquid surface reflected wave, which is a wave of the first transmission wave reflected by the liquid surface of the water-soluble coolant, and the signal strength of a second liquid surface reflected wave, which is a wave of the second transmission wave reflected by the liquid surface of the water-soluble coolant, When oil-based coolant is stored in the coolant tank, the machine tool determines the measurement result based on the signal strength of a first liquid surface reflected wave, which is a wave of the first transmission wave reflected by the liquid surface of the oil-based coolant, and the signal strength of a second bottom reflected wave, which is a wave of the second transmission wave reflected by the bottom surface of the coolant tank.

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