JP2023116045A - Abnormality detection device - Google Patents

Abstract

To provide an abnormality detection device which can detect a thermal abnormality generated in a machine tool when a processing operation of the machine tool stops.SOLUTION: An abnormality detection device 50 comprises: a temperature detection unit 25 which detects the temperature in a processing area of a machine tool 1 and the relevant temperature related to the temperature in the processing area; and a thermal abnormality determination unit 30 which determines that a prescribed thermal abnormality is generated in the machine tool when a detection temperature Ta detected by the temperature detection part 25 is equal to or greater than a preset threshold temperature T1 in a non-processing state in which the processing operation of the machine tool stops, and determines that the prescribed thermal abnormality is not generated when the detection temperature Ta is less than the threshold temperature T1.SELECTED DRAWING: Figure 3

Description

The present invention relates to an abnormality detection device for machine tools.

2. Description of the Related Art Conventionally, there has been known an abnormality detection device that detects an abnormality in a machine tool based on the temperature detected by a temperature sensor provided in the machine tool. For example, in the abnormality detection device of Patent Document 1, it is determined whether or not an abnormality has occurred in the spindle based on the temperature detected by the temperature sensor for the spindle during machining control of the machine tool. Specifically, this abnormality detection device has a spindle temperature sensor and a clock section for measuring the coasting time when the rotation of the spindle is stopped. Based on the relationship between the coasting time and the spindle temperature detected by the spindle temperature sensor, it is determined whether or not there is an abnormality in the spindle. Abnormalities of the spindle that can be detected by this abnormality detection device include, for example, roughness of the bearing raceway surface of the spindle, occurrence of rust on the raceway surface, and generation of foreign matter inside the bearing.

JP 2016-215311 A

The abnormality detection device of Patent Document 1 detects an abnormality such as roughness of the raceway surface of the spindle or the occurrence of rust. It is conceivable to detect an abnormal temperature rise in the machine tool caused by heat generated by the motor or the addition of an external heat source.
However, in the abnormality detection device of Patent Document 1, the abnormality detection process is executed only during the machining operation of the machine tool. Even so, there is a problem that a thermal abnormality cannot be detected when the machining operation of the machine tool is stopped.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an anomaly detection device capable of detecting thermal anomalies occurring in a machine tool while the machining operation of the machine tool is stopped. aim.

One aspect of the present invention for solving the above problems is an abnormality detection device for a machine tool, which detects a temperature within a machining area of the machine tool or a related temperature related to the temperature within the machining area. and when the detected temperature detected by the temperature detection unit is equal to or higher than a preset threshold temperature in a non-machining state in which the machining operation of the machine tool is stopped, a predetermined thermal abnormality has occurred in the machine tool. and a thermal abnormality determination unit that determines that the predetermined thermal abnormality has not occurred when the detected temperature is less than the threshold temperature while determining that the thermal abnormality has occurred.

According to this abnormality detection device, when the machine tool is in a non-machining state in which the machining operation is stopped, the temperature of the machining area or its related temperature exceeds the threshold temperature due to, for example, the heat generated by the spindle motor or the addition of an external heat source. In this case, the thermal abnormality determination section determines that a predetermined thermal abnormality has occurred in the machine tool. Therefore, it is possible to reliably detect a thermal abnormality that occurs when the machining operation of the machine tool is stopped. When the thermal abnormality determination unit determines that a thermal abnormality has occurred, for example, an alarm device or a thermal abnormality avoidance device for avoiding the thermal abnormality is activated to improve safety. be able to.

The machine tool includes a spindle, a spindle housing that rotatably holds the spindle, a spindle temperature sensor for detecting a temperature of the spindle housing, and a temperature of the spindle housing detected by the spindle temperature sensor. and a thermal displacement correction unit for correcting the feed movement amount of the feed mechanism provided in the machine tool based on is preferably configured to detect the temperature of as the relevant temperature.

According to this configuration, the spindle temperature sensor used for correcting the thermal displacement of the machine tool is also used as the temperature detection section, so that the parts can be shared and the device cost can be reduced. can.

The machine tool has a spindle, a spindle housing that rotatably holds the spindle, and an area temperature sensor that is attached to a cover member that covers the circumference of the spindle housing and detects the temperature in the machining area, It is preferable that the area temperature sensor constitutes the temperature detection section.

According to this configuration, by using the area temperature sensor attached to the cover member that covers the periphery of the spindle housing as the temperature detection section, the temperature of the machining area can be directly detected by the temperature detection section.

It is preferable to further include an alarm device that issues an alarm when the thermal abnormality determination section determines that the predetermined thermal abnormality has occurred.

According to this configuration, when the thermal abnormality determination section determines that a predetermined thermal abnormality has occurred, the alarm device issues an alarm. As a result, it is possible to further improve the safety when a thermal abnormality occurs in the machine tool.

The machine tool has a spindle, a spindle housing that rotatably holds the spindle, and a coolant supply device that supplies coolant to the spindle housing. The thermal abnormality determination unit determines whether or not the cooling liquid supply device is operating normally by the cooling determination unit in the non-machining state. Nevertheless, when the detected temperature detected by the temperature detection unit is equal to or higher than the threshold temperature, it is determined that the predetermined thermal abnormality has occurred in the machine tool. preferable.

According to this configuration, when the temperature detected by the temperature detection unit is equal to or higher than the preset threshold temperature even though the cooling determination unit determines that the cooling liquid supply device is operating normally. Only then, the thermal abnormality determination unit determines that the machine tool has a thermal abnormality. Therefore, a serious thermal abnormality that cannot be avoided even if the coolant supply device is operating normally can be reliably detected by the abnormality detection device.

According to the abnormality detection device according to the present invention, a temperature detection unit that detects the temperature in a machining area of a machine tool or a related temperature related to the temperature in the machining area, a thermal abnormality determination unit that determines that a predetermined thermal abnormality has occurred in the machine tool when the detected temperature detected by the temperature detection unit is equal to or higher than a preset threshold temperature in the state. By doing so, it is possible to reliably detect a thermal abnormality that occurs in the machine tool while the machine tool is in the non-machining state.

1 is a schematic side view showing a machine tool provided with an abnormality detection device according to an embodiment of the present invention; FIG. FIG. 2 is an explanatory diagram for explaining the arrangement position of a spindle temperature sensor and the outline of the cooling structure of the spindle; 3 is a control block diagram showing part of the control system of the machine tool; FIG. 4 is a flow chart showing the contents of normal processing control executed by a control device; 4 is a flowchart showing an example of thermal abnormality detection processing executed by the control device; FIG. 2 is a view equivalent to FIG. 2 showing an example of another embodiment;

An embodiment of the present invention will be described below with reference to the drawings.

<<Embodiment>>
FIG. 1 is a right side view showing a machine tool 1 having an abnormality detection device 50 according to the embodiment. This machine tool 1 is a horizontal machining center and includes a bed 2, a column 3, a spindle head 5, a spindle 6, a table 7 and the like. The machine tool 1 is entirely covered with a splash guard 12 that constitutes its appearance. Note that FIG. 1 showing the entire machine tool 1 shows only the essential parts, which are the main constituent elements of the machine tool 1 .

The bed 2 is generally formed in a T-shape in a plan view, and the table 7 is arranged on the bed 2 and guided by a guide rail (not shown) in the longitudinal direction of the bed 2, that is, horizontally. It is provided so as to move in the direction of the arrow Z-axis. A work W to be processed is set on the table 7 through a pallet P. As shown in FIG.

The column 3 is arranged on the bed 2 and guided by a guide rail 4 so as to move in the X-axis direction (perpendicular to the plane of FIG. 1) perpendicular to the Z-axis. A spindle head 5 is supported on the column 3 . The spindle head 5 has a spindle housing 5a (see FIG. 2) that rotatably holds the spindle 6 by means of bearings (not shown), and rotates along the vertical arrow Y-axis perpendicular to the X-axis and Z-axis. is held on the column 3 so as to be movable in the direction of Thus, the spindle head 5 moves within the X-Y plane.

The column 3 is driven to feed in the X-axis direction by an X-axis feed mechanism (not shown), the spindle head 5 is driven to feed in the Y-axis direction by a Y-axis feed mechanism (not shown), and the table 7 is driven to feed in the Z-axis direction. It is driven to feed in the Z-axis direction by a feed mechanism (not shown). These X-axis feed mechanism, Y-axis feed mechanism, and Z-axis feed mechanism are configured by, for example, a combination of a ball screw and a motor. Each feed mechanism, the main shaft 6 and a main shaft motor (not shown) for driving the main shaft 6 function as a machining mechanism section 10 .

A protective cover 9 is provided on the front side of the column 3 . The protective cover 9 is constructed by connecting a plurality of divided cover bodies by a pantograph mechanism (not shown) provided on the rear side thereof. The protective cover 9 is arranged so as to separate the space above the bed 2 into a machining area A1 where the table 7 is arranged and a non-machining area A2 where the column 3 is arranged.

The machining mechanism 10 changes the relative positions of the tool K mounted on the spindle 6 and the workpiece W set on the table 7 under the control of a control device 30 (see FIG. 3), which will be described later. Process W into a desired shape.

The machine tool 1 includes a cutting fluid supply device 13 (see FIG. 3) that supplies cutting fluid to the machining area A1 for the purpose of cooling and lubricating the machined portion and discharging chips, and a spindle housing 5a that holds the spindle 6. and a cooling liquid supply device 14 for supplying cooling liquid to the .

The cutting fluid supply device 13 sucks the cutting fluid stored in the storage tank by means of a supply pump (none of which is shown), and supplies the sucked cutting fluid to the machining portion of the workpiece W. As shown in FIG. After being supplied, the cutting fluid is collected in the storage tank through a return pipe connected to the bottom of the bed 2 .

As shown in FIG. 2, the coolant supply device 14 is connected to a supply pipe 17 connected to the proximal end of the spindle housing 5a and a return pipe 18 connected to the distal end of the spindle housing 5a. Inside the spindle housing 5a, a cooling passage (not shown) is formed through which the cooling liquid supplied from the supply pipe 17 is helically circulated around the axis of the spindle 6 and then discharged to the return pipe 18. The cooling liquid supply device 14 supplies the cooling liquid to the cooling passage through the supply pipe 17 and recovers the cooling liquid through the return pipe 18 . Then, the coolant supply device 14 compares the temperature of the collected coolant with the target temperature, controls the coolant to the target temperature based on the comparison, and supplies the coolant to the supply pipe 17 . Thus, the cooling liquid circulates between the cooling passage and the cooling liquid supply device 14, thereby cooling the main shaft 6 and the main shaft housing 5a.

As shown in FIG. 3, the machine tool 1 has a control device 30. As shown in FIG. The control device 30 is composed of a computer including a CPU, a ROM, a RAM, etc., and controls the machining mechanism section 10, the cutting fluid supply device 13, the cooling fluid supply device 14, the operation panel 15, the alarm device 16, and the spindle. It is connected to the internal temperature sensor 25 and the like so that signals can be sent and received. The control device 30, the coolant supply device 14, and the spindle temperature sensor 25 constitute an abnormality detection device 50. As shown in FIG.

The operation panel 15 has an operation unit for performing various settings and operation commands for the machine tool 1 and a display unit for displaying the operating status of the machine tool 1 (both not shown). The operation unit includes a power button of the machine tool 1, a cycle execution button for causing the machine tool 1 to execute machining operations based on the NC program, and the like.

The alarm device 16 is a device that gives an alarm when a predetermined thermal abnormality occurs in the machine tool 1, and is composed of, for example, an alarm speaker and an alarm lamp. Here, the thermal abnormality of the machine tool 1 means that the machine tool 1 has a predetermined abnormal temperature rise due to heat generation of components of the machine tool 1 (spindle motor, etc.) or heat generated from an external heat source other than the components. means a state that arises.

The spindle temperature sensor 25 is arranged such that the detection portion at the tip thereof is positioned at the tip of the spindle housing 5a (see FIG. 2). The spindle temperature sensor 25 detects the temperature of the spindle housing 5 a and transmits the detected temperature information to the control device 30 . The spindle temperature sensor 25 functions as a temperature detection section.

The control device 30 estimates the amount of thermal displacement at the tip of the spindle 6 based on the temperature Ta detected by the spindle temperature sensor 25 when causing the machining mechanism section 10 to perform the machining operation of the workpiece W, and calculates the estimated amount of thermal displacement. is controlled (corrected) for the feed movement amount of each of the feed mechanisms. Further, the control device 30 determines whether or not the thermal abnormality has occurred based on the temperature Ta detected by the spindle temperature sensor 25, as will be described later. Thus, the control device 30 functions as a thermal displacement correction section and a thermal abnormality determination section.

Next, normal operation control of the machine tool 1 executed by the control device 30 will be described with reference to FIG.

In step S1, it is determined whether or not the power button is turned on based on the operation signal from the operation panel 15. If the determination is NO, the process returns, and if the determination is YES, the process proceeds to step S2. .

In step S2, the coolant supply device 14 is operated to circulate the coolant between the coolant supply device 14 and the cooling passage in the spindle housing 5a.

In step S3, the cutting fluid supply device 13 is operated to supply the cutting fluid to the machining area.

In step S4, based on the operation signal from the operation panel 15, it is determined whether or not the cycle execution button has been turned on. proceed to

In step S5, by executing the NC program stored in the program storage unit (not shown), the machining mechanism unit 10 is caused to perform machining operations based on the NC program. During this machining operation, as described above, the thermal displacement correction control based on the detected temperature Ta of the spindle temperature sensor 25 is executed in parallel.

In step S6, it is determined whether or not the machining operation based on the NC program has ended. return.

Next, an example of thermal abnormality detection processing executed by the control device 30 will be described with reference to FIG.

At the first step S10, it is determined whether or not the machine tool 1 is in the non-machining state. Here, the determination in step S10 is made based on the execution status of the NC program in the control device 30, for example. That is, when the NC program is not being executed, it is determined that the machine tool 1 is in the non-machining state, and when the NC program is being executed, it is determined that the machine tool 1 is in the processing state. do. Here, the machining state is a state in which the machining mechanism unit 10 is operating based on the NC program, and the non-machining state is a state in which the operation of the machining mechanism unit 10 is stopped (the NC program itself is not being executed, or the NC program is interrupted during execution), and whether or not the workpiece W is actually being machined is irrelevant for the determination. Therefore, for example, a state in which the machining mechanism unit 10 is being trial-run based on the NC program without setting the workpiece W on the table 7 corresponds to a machining in progress state.

In step S11, it is determined whether or not the temperature Ta detected by the spindle temperature sensor 25 is equal to or higher than a preset first threshold temperature T1. goes to step S12.

In step S12, it is determined whether or not the coolant supply device 14 is operating normally. This determination is based on, for example, the number of revolutions of a circulation pump that constitutes the cooling liquid supply device 14, the temperature difference between the cooling liquid flowing through the supply pipe 17 and the return pipe 18 (that is, the amount of cooling by the cooling liquid supply device 14), and the like. is performed on The control device 30 also functions as a cooling determination unit by executing this step S12.

If the determination is NO, the process proceeds to step S14, and a message indicating that the coolant supply device 14 is out of order (not operating normally) is displayed on the display section of the operation panel 15, and then Return later. On the other hand, if the determination is YES (that is, if the detected temperature Ta of the spindle temperature sensor 25 exceeds the first threshold temperature T1 even though the coolant supply device 14 is operating normally), Proceed to step S13.

In step S13, it is determined that the machine tool 1 has a thermal abnormality, and the alarm device 16 is activated. This makes it possible for the operator of the machine tool 1 and workers in the vicinity to recognize the occurrence of the thermal abnormality. After executing the process of step S13, the process returns.

In step S15, which is followed when the determination in step S10 is NO, it is determined whether or not the temperature Ta detected by the spindle temperature sensor 25 is equal to or higher than a preset second threshold temperature T2. On the other hand, if the answer is YES, the process proceeds to step S16. Here, the second threshold temperature T2 is a threshold temperature for detecting whether or not the thermal abnormality occurs when the machine tool 1 is in the machining state, and is higher than the first threshold temperature T1. set high.

In step S16, the execution of the NC program is interrupted or stopped to stop the machining operation of the machining mechanism section 10, and then the process proceeds to step S12. The processing after step S12 is as described above.

As described above, when the controller 30 determines that the detected temperature Ta detected by the spindle temperature sensor 25 is equal to or higher than the preset first threshold temperature T1 in the non-machining state of the machine tool 1, is configured to determine that the machine tool 1 has a thermal abnormality.

According to this configuration, it is possible to determine whether or not a thermal abnormality has occurred in the machine tool 1 not only in the machining state of the machine tool 1 but also in the non-machining state. Therefore, for example, after the machining operation by the machining mechanism section 10 is completed, heat is generated in the machine tool 1 due to heat generated by the spindle motor, which is a component of the machine tool 1, or heat generated by an external heat source other than the components of the machine tool 1. Even if an abnormality occurs, the thermal abnormality can be reliably detected based on the temperature Ta detected by the spindle temperature sensor 25 .

In particular, in the present embodiment, the control device 30 determines that the detection temperature Ta detected by the spindle temperature sensor 25 is equal to or higher than the preset first threshold temperature T1 even though the coolant supply device 14 is operating normally. It is configured to determine that a thermal abnormality has occurred in the machine tool 1 when it is determined that it is.

As a result, the control device 30 can reliably detect a serious thermal abnormality that cannot be avoided even if the coolant supply device 14 is operating normally.

The control device 30 is configured to activate the alarm device 16 when the thermal abnormality is detected. As a result, not only the operator of the machine tool 1 but also the surrounding workers can recognize the occurrence of the thermal abnormality, thereby improving the safety.

The control device 30 is configured to perform thermal displacement correction during workpiece machining based on the temperature Ta detected by the spindle temperature sensor 25. Also used as a sensor.

According to this, compared to the case where a dedicated temperature sensor for detecting thermal abnormality is provided, parts can be shared and the product cost can be reduced.

<<Other embodiments>>
In the above embodiment, the spindle temperature sensor 25 was used as an example of a temperature sensor that detects the temperature related to the temperature in the machining area A1. The temperature of the bed 2 or the temperature of the column 3 may be detected as the temperature related to the temperature of . That is, the related temperature related to the temperature in the processing area A1 may be the temperature of any part as long as it changes with the temperature in the processing area A1.

Further, as shown in FIG. 6, the area temperature sensor 26 may directly detect the temperature of the processing area A1. In the example of FIG. 6, the area temperature sensor 26 is attached to the surface of the sheet metal spindle cover 20 (an example of the cover member) surrounding the spindle housing 5a. , may be attached to the inner surface of the splash guard 12, or the like. As the temperature sensor 26, a thermocouple or a camera (thermography) sensitive to infrared rays may be employed.

In the above-described embodiment, the control device 30 is configured to activate the alarm device 16 when a thermal abnormality of the machine tool 1 is detected. When an abnormality is detected, it is preferable to operate a thermal abnormality avoidance device for avoiding the thermal abnormality. As the thermal abnormality avoidance device, for example, a device that injects cooling liquid or gas into the processing area A1 can be employed. In addition, for example, when the temperature Ta detected by the temperature sensors 25 and 26 exceeds the first threshold temperature T1, only the alarm device 16 is activated, and the detected temperature Ta exceeds the first threshold temperature T1 and the second threshold temperature T2. The thermal abnormality avoidance device may be activated when the third threshold temperature T3, which is higher than T3, is exceeded. According to this, since the thermal abnormality avoidance device needs to be activated only when the degree of thermal abnormality (abnormality level) is high, unnecessary operation of the thermal abnormality avoidance device can be prevented.

In the above-described embodiment, the controller 30 controls the temperature Ta detected by the spindle temperature sensor 25 to exceed the first threshold temperature T1 even though the coolant supply device 14 is operating normally (steps S11 and (If both are YES in S12), it is determined that the machine tool 1 has a thermal abnormality, but the present invention is not limited to this. That is, when step S12 is abolished and the temperature Ta detected by the temperature sensor 26 exceeds the first threshold temperature T1, the heat generated by the machine tool 1 is detected regardless of whether the coolant supply device 14 is operating normally. It may be determined that an abnormality has occurred.

It should be noted that the above description of the embodiment is illustrative in all respects and is not restrictive. Modifications and modifications are possible for those skilled in the art. The scope of the invention is indicated by the claims rather than the above-described embodiments. Furthermore, the scope of the present invention includes modifications from the embodiments within the scope of claims and equivalents.

A1 processing area T1 first threshold temperature (threshold temperature)
Ta Detected temperature 1 Machine tool 5 Spindle head 5a Spindle housing 6 Spindle 16 Alarm device 20 Spindle cover (cover member)
25 Main shaft temperature sensor (temperature detection unit)
26 area temperature sensor (temperature detector)
30 control device (thermal abnormality determination unit, cooling determination unit)
50 Abnormality detection device

The alarm device 16 is a device that gives an alarm when a predetermined thermal abnormality occurs in the machine tool 1, and is composed of, for example, an alarm speaker and an alarm lamp. Here, the thermal abnormality of the machine tool 1 means that the temperature of the machine tool 1 rises above a predetermined level due to heat generated by components of the machine tool 1 (spindle motor, etc.) or heat generated by an external heat source other than the components. means a state that arises.

Claims (5)

An abnormality detection device for a machine tool,
a temperature detector for detecting a temperature within a working area of the machine tool or a related temperature related to the temperature within the working area;
In a non-machining state in which the machining operation of the machine tool is stopped, if the detected temperature detected by the temperature detection unit is equal to or higher than a preset threshold temperature, a predetermined thermal abnormality has occurred in the machine tool. and a thermal abnormality determination unit that determines that the predetermined thermal abnormality does not occur when the detected temperature is lower than the threshold temperature. The machine tool includes a spindle, a spindle housing that rotatably holds the spindle, a spindle temperature sensor for detecting a temperature of the spindle housing, and a temperature of the spindle housing detected by the spindle temperature sensor. and a thermal displacement correction unit that corrects the feed movement amount of the feed mechanism provided in the machine tool based on
2. The abnormality detection device according to claim 1, wherein said spindle temperature sensor is also used as said temperature detection section, and is configured to detect the temperature of said spindle housing as said related temperature. The machine tool has a spindle, a spindle housing that rotatably holds the spindle, and an area temperature sensor that is attached to a cover member that covers the circumference of the spindle housing and detects the temperature in the machining area,
2. The abnormality detection device according to claim 1, wherein said area temperature sensor constitutes said temperature detection unit. 4. The apparatus according to any one of claims 1 to 3, further comprising an alarm device that issues an alarm when the thermal abnormality determination section determines that the predetermined thermal abnormality has occurred. Anomaly detector. The machine tool includes a spindle, a spindle housing that rotatably holds the spindle, and a coolant supply device that supplies coolant to the spindle housing,
further comprising a cooling determination unit that determines whether the cooling liquid supply device is operating normally,
The thermal abnormality determination unit detects the temperature detected by the temperature detection unit in the non-machining state even though the cooling determination unit determines that the coolant supply device is operating normally. is equal to or higher than the threshold temperature, it is determined that the predetermined thermal abnormality has occurred in the machine tool. An anomaly detection device as described.

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