Elevated temperature value estimating method of machine tool, thermal displacement amount estimating method, bearing cooling device control method, and machine tool

Abstract

To provide a method for accurately estimating an elevated temperature value at a place where heat is generated, in accordance with a state of the place where heat is generated, in a machine tool equipped with a cooling device, a method for estimating a thermal displacement amount at the place where heat is generated, a method for controlling the cooling device for cooling the place where heat is generated, and a machine tool that can execute the method for estimating the elevated temperature value.SOLUTION: A machine tool, which is equipped with a spindle cooling device 7, comprises temperatures sensors 13 and 14 which can measure a temperature of the machine tool and a temperature of a spindle 3, which determines an operation state of the spindle cooling device 7 and determines whether a time measured based on the fact that the spindle cooling device 7 is operated or stopped passes over a preset delay time or not, so as to determine a cooling state of the spindle 3, selects a suitable estimation model corresponding to the cooling state of the spindle 3 out of a plurality of estimation models A-D corresponding to different cooling states of the spindle 3, and calculates an estimated elevated-temperature value of the spindle 3 on the basis of the estimation mode and temperature data derived from measurement values obtained by the temperature sensors 13 and 14.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a method for accurately estimating a temperature rise value of a heat generating location in a machine tool equipped with a cooling device depending on the state of the heat generating location, a method for estimating a thermal displacement amount of the heat generating location, a method for controlling a cooling device for cooling the heat generating location of a machine tool, and a machine tool capable of executing the method for estimating the temperature rise value. [Background technology]

[0002] In machining with machine tools such as machining centers, for example, in rotating shafts such as spindles, friction between the rotating shaft and bearings can cause heat generation and thermal displacement in the axial direction. Thermal displacement can lead to deterioration of machining accuracy. In order to prevent thermal displacement, a common method is to provide a flow path in the housing outside the bearing to allow cooling oil to flow and to remove the heat of the cooling oil with a cooling device. However, the power consumption of the cooling device for the rotating shaft accounts for a large proportion of the power consumption of the peripheral devices of the machine tool. Therefore, from the viewpoint of carbon neutrality, the operation of the cooling device is controlled to reduce power consumption. Patent Document 1 discloses a method for reducing power consumption by controlling the operation of the cooling device when the temperature near the spindle calculated using the spindle temperature rise value meets a predetermined threshold value when the spindle is stopped. On the other hand, in order to suppress the effect of thermal displacement on machining accuracy, a method of estimating the amount of thermal displacement from machine temperature information and correcting the phase may be used. For example, Patent Document 2 discloses a calculation method for estimating the spindle thermal displacement by changing the calculation coefficient of a thermal displacement estimation calculation formula according to the rotation speed and time or the number of corrections.

[0003] Furthermore, when the rotating shaft rotates, if there is a bearing abnormality or insufficient bearing lubrication in addition to heat generation, problems such as bearing seizure may occur. To prevent such problems, Patent Document 3 discloses a method for measuring the temperature difference between the inner and outer rings of a bearing using a heat flow sensor and detecting a sudden temperature rise due to a bearing abnormality or lubrication abnormality. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6445395 [Patent Document 2] Japanese Patent Application Publication No. 9-225781 [Patent Document 3] Patent No. 6967495 Summary of the Invention [Problem to be solved by the invention]

[0005] With the acceleration of energy-saving measures to realize a carbon-free society, power consumption reduction by controlling the operation of the spindle cooling device should be performed not only when the machine is stopped as disclosed in Patent Document 1, but also when the machine is operating. However, when the operation of the spindle cooling device is controlled while the machine is operating, the thermal displacement characteristics differ between when the spindle cooling device is operating and when it is stopped, so the amount of thermal displacement cannot be accurately estimated by the method disclosed in Patent Document 2. Therefore, in order to accurately estimate the amount of thermal displacement, it is necessary to use an estimation model according to the state of the heat generating point. On the other hand, if the cooling capacity during shaft rotation is reduced in order to suppress the fluctuation of the thermal displacement characteristics, the bearing may rise in temperature and cause problems such as seizure. In addition, when the reduced cooling capacity is restored, the outer ring side of the bearing may be cooled rapidly, increasing the temperature difference between the inner and outer rings, which may cause seizure. For this reason, in order to control the operation of the cooling device while monitoring the temperature difference between the inner and outer rings during machine operation, it is necessary to measure the temperature of the inner ring. However, the method of detecting the temperature difference between the inner and outer rings disclosed in Patent Document 3 requires a heat flow sensor to be installed in a spacer near the bearing, making it difficult to handle the measurement means. Therefore, if it is possible to accurately estimate a value equivalent to the temperature of the inner ring of the bearing using an estimation model according to the state of the bearing, which is the heat generating point, it is thought that the difficulty in handling the measurement means can be solved.

[0006] Therefore, an object of the present disclosure is to provide a temperature rise value estimation method for a machine tool and a machine tool that can accurately estimate the temperature rise value occurring at a heat generation location based on the state of a cooling device for cooling the heat generation location and an estimation model selected according to the state of the heat generation location, and temperature information of the machine body. Another object of the present disclosure is to provide a method for estimating the amount of thermal displacement of a machine tool that can accurately estimate the amount of thermal displacement occurring at a heat-generating location from an estimation model selected according to the state of a cooling device for cooling the heat-generating location and the state of the heat-generating location, and a temperature rise value at the heat-generating location estimated based on temperature information of the machine body. Another object of the present disclosure is to provide a bearing cooling device control method capable of monitoring the temperature difference between the inner and outer rings of a bearing and controlling the operation of the bearing cooling device during machine operation using an estimation model selected according to the state of the bearing cooling device and the state of the bearing, and a bearing temperature rise value estimated based on temperature information of the machine body. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, a first configuration of the present disclosure is characterized in that, in a machine tool equipped with a cooling device capable of cooling a specific part that generates heat due to operation of the machine, the machine is provided with a plurality of temperature sensors arranged at any positions including a position where at least a body temperature can be measured and a position where a temperature of the specific part can be measured, the cooling state of the specific part is determined by determining whether the cooling device is in an operating state or a stopped state, and determining whether a time measured from a base point of operation or stop of the cooling device has elapsed a preset delay time, an appropriate estimation model corresponding to the determined cooling state of the specific part is selected from a plurality of estimation models preset to correspond to different cooling states of the specific part, and an estimated temperature rise value of the specific part is calculated based on the selected estimation model and temperature data derived from measured values ​​obtained by the plurality of temperature sensors. Another aspect of the first configuration of the present disclosure is characterized in that, in the above configuration, the cooling state of a specified part is determined to be one of at least four states: a temperature decreasing transient state from when the cooling device is operated until a delay time has elapsed, a temperature increasing transient state from when the cooling device is stopped until a delay time has elapsed, a cooling stable state after the cooling device is operated and a delay time has elapsed, and a heating stable state after the cooling device is stopped and a delay time has elapsed. Another aspect of the first configuration of the present disclosure is characterized in that, in the above configuration, the delay time is calculated from a value obtained based on the operation of a predetermined portion, using a predetermined function. Another aspect of the first configuration of the present disclosure is characterized in that, in the above configuration, the delay time is determined by calculating the amount of change per time for at least one of the temperature data and the estimated temperature rise value at a specified location, and determining the time until the calculated amount of change per time becomes greater than a preset threshold value. In order to achieve the above-mentioned object, a second configuration of the present disclosure is characterized in that in a machine tool equipped with a cooling device capable of cooling a specific part that generates heat due to operation of the machine, the machine is provided with a plurality of temperature sensors arranged at any positions including a position where at least a body temperature can be measured and a position where the temperature of the specific part can be measured, and the cooling state of the specific part is determined by determining whether the cooling device is in an operating state or a stopped state and determining whether a time measured from a base point of operation or stop of the cooling device has elapsed a preset delay time, an appropriate estimation model corresponding to the determined cooling state of the specific part is selected from a plurality of estimation models preset to correspond to different cooling states of the specific part, an estimated temperature rise value of the specific part is calculated based on the selected estimation model and temperature data derived from measured values ​​obtained by the plurality of temperature sensors, and an amount of thermal displacement of the specific part is estimated using the calculated estimated temperature rise value of the specific part and a coefficient based on the selected estimation model for converting the temperature rise value of the specific part into an amount of thermal displacement. Another aspect of the second configuration of the present disclosure is characterized in that, in the above configuration, the cooling state of a specified part is determined to be one of at least four states: a temperature decreasing transient state from when the cooling device is operated until a delay time has elapsed, a temperature increasing transient state from when the cooling device is stopped until a delay time has elapsed, a cooling stable state after the cooling device is operated and a delay time has elapsed, and a heating stable state after the cooling device is stopped and a delay time has elapsed. Another aspect of the second configuration of the present disclosure is characterized in that, in the above configuration, the delay time is calculated from a value obtained based on the operation of a predetermined portion, using a predetermined function. Another aspect of the second configuration of the present disclosure is characterized in that, in the above configuration, the delay time is determined by calculating the amount of change per time for at least one of the temperature data and the estimated temperature rise value at a specified location, and determining the time until the calculated amount of change per time becomes greater than a preset threshold value. In order to achieve the above object, a third configuration of the present disclosure provides a machine tool having a rotating shaft, the machine tool having a cooling device provided with a path for cooling at least an outer ring side of a bearing of the rotating shaft, the machine tool having a plurality of temperature sensors arranged at any positions including a position where at least a machine body temperature can be measured and a position where a temperature of the outer ring side of the bearing can be measured, and the cooling device judges whether the cooling device is in an operating state or a stopped state, and judges whether a time measured from a point of operation or stop of the cooling device has passed a preset delay time, thereby judging the state of the bearing, and the judgment is made based on a plurality of estimation models preset to correspond to different cooling states of the bearing. the cooling state of the bearing is selected, an estimated temperature rise value of the inner ring side of the bearing is calculated using coefficients based on the selected estimation model and temperature data derived from measurement values ​​obtained by a plurality of temperature sensors, an estimated inner / outer ring temperature difference is calculated from the calculated estimated temperature rise value of the inner ring side of the bearing and a temperature rise value of the outer ring side of the bearing calculated based on temperature data derived from measurement values ​​obtained from a temperature sensor that measures the temperature of the outer ring side of the bearing, and the cooling device is started or stopped when the estimated inner / outer ring temperature difference exceeds or falls below a predetermined threshold based on the selected estimation model. Another aspect of the third configuration of the present disclosure is characterized in that, in the above configuration, it is determined whether the cooling state of the bearing is in any of at least four states: a temperature decreasing transient state from when the cooling device is operated until a delay time has elapsed, a temperature increasing transient state from when the cooling device is stopped until a delay time has elapsed, a cooling stable state after the cooling device is operated and a delay time has elapsed, or a heating stable state after the cooling device is stopped and a delay time has elapsed. Another aspect of the third configuration of the present disclosure is characterized in that in the above configuration, the delay time is calculated from the rotation speed of the rotating shaft by using a predetermined function. Another aspect of the third configuration of the present disclosure is characterized in that, in the above configuration, the delay time is determined by calculating the amount of change per time for at least one of the temperature data, the estimated temperature rise value on the inner ring side of the bearing, and the estimated inner / outer ring temperature difference, and setting the delay time as the time until the calculated amount of change per time becomes greater than a preset threshold value. In order to achieve the above-mentioned object, a fourth configuration of the present disclosure is a machine tool equipped with a cooling device capable of cooling a specific part that generates heat due to operation of the machine, and is characterized in that it is equipped with a plurality of temperature sensors arranged at any positions including a position where at least a body temperature can be measured and a position where the temperature of the specific part can be measured, and is equipped with a device for determining whether the cooling device is in an operating state or a stopped state, and for determining whether a time measured from a base point of operation or stop of the cooling device has elapsed a preset delay time, thereby determining the state of the specific part, selecting an appropriate estimation model corresponding to the determined cooling state of the specific part from a plurality of estimation models preset to correspond to different cooling states of the specific part, and calculating an estimated temperature rise value of the specific part based on the selected estimation model and temperature data derived from measured values ​​obtained by the plurality of temperature sensors. Another aspect of the fourth configuration of the present disclosure is characterized in that, in the above configuration, the cooling state of a specified part is determined to be one of at least four states: a temperature decreasing transient state from when the cooling device is operated until a delay time has elapsed, a temperature increasing transient state from when the cooling device is stopped until a delay time has elapsed, a cooling stable state after the cooling device is operated and a delay time has elapsed, and a heating stable state after the cooling device is stopped and a delay time has elapsed. Effect of the Invention

[0008] According to the first and fourth disclosures of the present invention, when estimating a temperature rise value that occurs in a specific part to be cooled due to operation or stoppage of a cooling device during machine operation, the temperature rise value of the part can be accurately estimated by selecting an estimation model that corresponds to the cooling state of the part that changes due to operation or stoppage of the cooling device. According to the second disclosure of the present invention, when estimating the amount of thermal displacement occurring in a specific part to be cooled due to operation or stop of a cooling device during machine operation, the amount of thermal displacement occurring in the part can be accurately estimated by selecting an estimation model corresponding to the cooling state of the part that changes due to operation or stop of the cooling device. Therefore, even if the cooling device is operated or stopped during machine operation, accurate correction of the thermal displacement occurring in the part can be made, and deterioration of machining accuracy can be prevented. According to the third disclosure of the present invention, when estimating the inner / outer ring temperature difference occurring in a bearing to be cooled due to operation or stop of a cooling device during machine operation, the inner / outer ring temperature difference occurring in the bearing can be accurately estimated by selecting an estimation model corresponding to the cooling state of the bearing that changes due to operation or stop of the cooling device. Therefore, it becomes possible to control the cooling device according to the estimated inner / outer ring temperature difference, and by stabilizing the temperature of the bearing during operation, problems such as bearing seizure can be prevented. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is an explanatory diagram showing a main part of a machine tool according to a first embodiment. [Diagram 2] 4 is a flowchart showing a method for estimating a thermal change amount in the present disclosure. [Diagram 3] FIG. 11 is an explanatory diagram showing a main part of a machine tool according to a second embodiment. [Figure 4] 4 is a flowchart illustrating a control method for a cooling device according to the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is an explanatory diagram showing the main part of the machine tool of the embodiment 1. In addition, in the machine tool shown in Fig. 1, a cover and other equipment are omitted, but in reality, the machine tool is provided with a cover and other equipment that are not shown.

[0011] 1, the machine tool of the first embodiment includes a machining center 6 provided with a bed 1, a column 2, a spindle 3, a spindle unit 4 including a bearing, and a table 5, a spindle cooling device 7, a temperature setting device 8, a correction amount calculation device 9, and an NC device 10. The spindle unit 4 includes a cooling oil supply unit 11 and a cooling oil discharge unit 12 in an outer cylindrical portion of the spindle housing. A cooling circuit is provided between the machining center 6 and the spindle cooling device 7, through which cooling oil is supplied to the cooling oil supply unit 11 and returned to the spindle cooling device 7 from the cooling oil discharge unit 12. That is, in the first embodiment, the spindle unit 4 is a predetermined portion that generates heat due to operation of the machine in the present disclosure, and is a target for cooling during operation of the machine.

[0012] The machining center 6 is provided with a temperature sensor 13 disposed on the column 2 for detecting the body temperature, which is the reference temperature, and a temperature sensor 14 disposed on the spindle unit 4 for detecting the spindle temperature. The temperature sensors 13 and 14 are connected to the temperature setting device 8, and the temperature measurements taken by the temperature sensors 13 and 14 are transmitted to the temperature setting device 8.

[0013] The NC device 10 is connected to the machining center 6, and the operation of the machining center 6 is controlled by receiving commands from the NC device 10. The NC device 10 is also connected to the spindle cooling device 7, the temperature setting device 8 capable of performing digitalization processing of temperature measurements obtained from temperature sensors 13 and 14, and the correction amount calculation device 9 that calculates a correction amount from an estimated amount of thermal displacement, which will be described later, and is responsible for controlling each of them.

[0014] The spindle cooling device 7 is set so that operation and stop are switched on and off when the difference between the machine body temperature detected by the temperature sensor 13 when the spindle is operating at the maximum rotational speed during machine operation of the machine tool and the spindle temperature detected by the temperature sensor 14 exceeds or falls below a preset threshold value.

[0015] Next, a method for estimating the amount of thermal change according to the present disclosure will be described. FIG. 2 is a flowchart showing a method for estimating a thermal change amount in the present disclosure. During the operation of the machine tool, the NC device 10 measures time based on the timing when the spindle cooling device 7 is operated or stopped (S1). When it is determined that a change has occurred in the operation control of the spindle cooling device 7, such as operation or stop, (S2), the time measurement is reset (S3). Thereafter, the measurement of time is restarted based on the timing when the measured time was reset, that is, the timing when the spindle cooling device 7 was switched between operation and stop. Note that the judgments, calculations, etc. executed in the following description are executed by the NC device 10 unless otherwise specified.

[0016] Next, at the time when the thermal change amount estimation is performed, it is determined whether the spindle cooling device 7 is operating or stopped (S4). If it is determined that the spindle cooling device 7 is operating, the measured time up to the point in time when the thermal change amount estimation is executed is compared with a preset delay time (S5).

[0017] As a result of comparing the measured time with the delay time, if the measured time is longer than the delay time, it is determined that the cooling state of the spindle unit 4 is a stable cooling state after the delay time or more has elapsed since the spindle cooling device 7 was operated. Then, as an estimation model used for estimating the thermal displacement amount, an estimation model A preset to correspond to the stable cooling state is set (S6). If the measured time is shorter than the delay time, it is determined that the cooling state of the spindle unit 4 is a temperature drop transient state from the operation of the spindle cooling device 7 until the delay time has elapsed. Then, as an estimation model, an estimation model B preset to correspond to the temperature drop transient state is set (S7).

[0018] On the other hand, even if it is determined in S4 that the spindle cooling device 7 is stopped, the time measured up to the time when the thermal change amount estimation is performed is compared with the preset delay time (S8). As a result of comparing the measured time with the delay time, if the measured time is longer than the delay time, it is determined that the cooling state of the spindle unit 4 is a heating stable state after the delay time or more has elapsed since the spindle cooling device 7 was stopped. Then, as the estimation model, an estimation model C preset to correspond to the heating stable state is set (S9). On the other hand, if the measured time is shorter than the delay time, it is determined that the cooling state of the spindle unit 4 is a temperature rise transient state from the time the spindle cooling device 7 was stopped until the delay time has elapsed. Then, as the estimation model, an estimation model D preset to correspond to the temperature rise transient state is set (S10).

[0019] The delay times used in S5 and S8 are determined experimentally in advance by measuring the time from the timing of starting or stopping the spindle cooling device 7 until the spindle unit 4 is cooled to a desired temperature and stabilized at that temperature, or the time until the temperature rises from a cooled state and stabilizes at a certain temperature.

[0020] The estimation models A, B, C, and D include coefficients, functions, and the like used to estimate the temperature rise value, thermal displacement amount, and the like of a predetermined portion, which will be described later. The coefficients, functions, and the like of the estimation models A, B, C, and D are determined in advance by experimentally deriving the temperature rise value, thermal displacement amount, and the like of the spindle unit 4 so that they correspond to the cooling state of the spindle unit 4.

[0021] In S6 to S7 and S9 to S10, an estimation model corresponding to the cooling state of the spindle unit 4 is selected, and then the temperature sensors 13, 14 measure the machine body temperature and the spindle temperature (S11). The measured temperatures are collected by the temperature setting device 8, and converted from analog signals to digital signals and digitized by a known method at a preset cycle.

[0022] The temperature setting device 8 calculates an estimated spindle temperature rise value by using the digitized temperature data and Equation 1 including a function for equalizing the time response of temperature and thermal displacement preset for each estimation model (S12). The calculated estimated spindle temperature rise value is sent to the correction amount calculation device 9.

[0023]

number

[0024] i=1 indicates the state after the operation state of the spindle cooling device is switched to ON and a preset delay time has elapsed, that is, estimation model A of a cooling stable state. i=2 indicates the state after the operation state of the spindle cooling device is switched to ON and a preset delay time has elapsed, that is, estimation model B of a temperature drop transient state. i=3 indicates the state after the operation state of the spindle cooling device is switched to STOP and a preset delay time has elapsed, that is, estimation model C of a heating stable state. i=4 indicates the state after the operation state of the spindle cooling device is switched to STOP and a preset delay time has elapsed, that is, estimation model D of a temperature rise transient state.

[0025] Thereafter, the correction amount calculation device 9 calculates an estimated spindle thermal displacement amount by using Equation 2 including a conversion coefficient from the spindle temperature rise value to the spindle thermal displacement amount, which is set in advance for each estimation model, for the estimated spindle temperature rise value calculated by the temperature setting device 8 (S13).

[0026]

number

[0027] Then, the correction amount calculation device 9 calculates the correction amount necessary to maintain the machining accuracy from the estimated spindle thermal displacement amount calculated in S13. The calculated correction amount is sent to the NC device 10 and fed back to the operation of the machining center 6. It is then determined whether or not to continue estimating the amount of thermal change (S14), and if it is to be continued, the process is restarted from the step (S2) of determining a change in the operation control of the spindle cooling device 7.

[0028] As described above, when estimating the amount of thermal displacement occurring in the spindle 3 due to operation or stop of the spindle cooling device 7 while the machining center 6 is in operation, the amount of thermal displacement occurring in the spindle 3 can be accurately estimated by selecting an estimation model corresponding to the cooling state of the spindle unit 4 that changes due to operation or stop of the spindle cooling device 7. Therefore, even if the spindle cooling device 7 is operated or stopped while the machining center 6 is in operation, accurate correction for the amount of thermal displacement occurring in the spindle 3 is possible, and deterioration of machining accuracy can be prevented.

[0029] FIG. 3 is an explanatory diagram showing a main part of a machine tool according to a second embodiment. As shown in Fig. 3, the machine tool of the second embodiment includes a machining center 6 provided with a bed 1, a column 2, a spindle 3 as a rotating shaft, a spindle unit 4 including bearings, and a table 5, a spindle cooling device 7, a temperature setting device 8, a temperature difference calculation device 15, a cooling capacity setting device 16, and an NC device 10. The spindle unit 4 includes a cooling oil supply unit 11 and a cooling oil discharge unit 12 in an outer cylindrical portion of the spindle housing. A cooling circuit is provided between the machining center 6 and the spindle cooling device 7, in which cooling oil is supplied to the cooling oil supply unit 11 and returned to the spindle cooling device 7 from the cooling oil discharge unit 12. That is, in the second embodiment, the spindle unit 4 is a predetermined portion that generates heat due to the operation of the machine in the present disclosure, and is a target for cooling during the operation of the machine.

[0030] The machining center 6 is provided with a temperature sensor 13 disposed on the column 2 for detecting the body temperature, which is the reference temperature, and a temperature sensor 14 disposed on the spindle unit 4 for detecting the spindle temperature. The temperature sensors 13 and 14 are connected to the temperature setting device 8, and the temperature measurements taken by the temperature sensors 13 and 14 are transmitted to the temperature setting device 8.

[0031] The NC device 10 is connected to the machining center 6, and the operation of the machining center 6 is controlled by receiving commands from the NC device 10. The NC device 10 is also connected to the spindle cooling device 7, a temperature setting device 8 capable of performing digitalization processing of temperature measurements acquired from temperature sensors 13 and 14, a temperature difference calculation device 15 that calculates an estimated amount of temperature difference between the inner and outer wheels of the spindle unit 4 from an estimated value of the temperature rise of the spindle, which will be described later, and a cooling capacity setting device 16 that sets the cooling capacity of the spindle cooling device 7, and is responsible for controlling each of them.

[0032] Next, a method for controlling the cooling device according to the present disclosure will be described. Fig. 4 is a flowchart showing a method for controlling the cooling device according to the present disclosure. Note that the flowchart in Fig. 4 assumes that, as initial settings, the spindle cooling device 7 is in an operating state and the cooling state of the spindle unit 4 is in a stable cooling state.

[0033] In the second embodiment, first, an estimation model is selected (S21). The selection of the estimation model is executed along S2 to S10 shown in Fig. 2. As described above, since the cooling state of the spindle unit 4 is a stable cooling state here, the estimation model A is selected. When an estimation model is selected in S21, the temperature of each part is measured by the temperature sensors 13, 14 (S22). The measured temperatures are collected by the temperature setting device 8, and converted from analog signals to digital signals and quantified by a known method at a preset cycle.

[0034] The temperature setting device 8 first calculates the outer ring side temperature rise value Δθb from the digitized temperature data. n , that is, the aircraft temperature θ1 n and outer ring temperature θ2 n The difference between the estimated inner ring temperature rise value Δθa and the estimated inner ring temperature rise value Δθa is calculated using Equation 4, which includes a coefficient α related to the time response and Equation 5, which includes a coefficient β related to the amount of change, which are preset for each estimation model. n The coefficients α and β set in each estimation model are determined in advance by testing or the like. n is sent to the temperature difference calculation device 15.

[0035]

number

number

number

[0036] The temperature difference calculation device 15 calculates the outer ring side temperature rise value Δθb calculated by the temperature setting device 8. n and the estimated inner ring temperature rise value Δθa n From the difference, the estimated inner and outer ring temperature difference Δθab n is calculated (S24). Calculated estimated inner / outer ring temperature difference Δθab nis compared with a preset threshold value A for determining whether cooling is turned OFF (S25). n exceeds the threshold A, the cooling state of the spindle unit 4 can be said to be a state in which further cooling is not required, such as the spindle temperature reaching a desired temperature. Therefore, the cooling capacity setting device 16 transmits a command to the spindle cooling device 7 via the NC device 10 to stop or operate with a cooling capacity that can maintain the spindle unit 4 at the desired temperature (S26). On the other hand, the estimated inner and outer ring temperature difference Δθab n If falls below threshold A, the estimated inner / outer ring temperature difference Δθab n is compared with a preset threshold value B for cooling ON determination (S27). If it falls below threshold value B for cooling ON determination, it can be said that the cooling state of the spindle unit 4 is such that the spindle temperature has not reached the desired temperature and further cooling is required. Therefore, the cooling capacity setting device 16 transmits a command to the spindle cooling device 7 via the NC device 10 to operate with a cooling capacity capable of cooling the spindle unit 4 to the desired temperature, for example, by increasing the cooling capacity (S28).

[0037] Next, it is determined whether or not a change has occurred in the operation control of the spindle cooling device 7 compared to the previous processing (S29). If it is determined that a change has occurred in the operation control of the spindle cooling device 7, the time measured up to that point is reset, and time measurement is restarted from the timing at which the measured time was reset (S30).

[0038] Subsequently, a determination is made as to whether the spindle cooling device 7 is operating or stopped (S31). If it is determined that the spindle cooling device 7 is operating, the time measured up to that point is compared with a preset delay time (S32).

[0039] As a result of comparing the measured time with the delay time, if the measured time is longer than the delay time, it is determined that the cooling state of the spindle unit 4 is a stable cooling state after the spindle cooling device 7 is operated and the delay time or more has elapsed. Then, as the estimation model, an estimation model A preset to correspond to the stable cooling state is set (S33). If the measured time is shorter than the delay time, it is determined that the cooling state of the spindle unit 4 is a temperature decreasing transient state from the operation of the spindle cooling device 7 until the delay time has elapsed. Then, as the estimation model, an estimation model B preset to correspond to the temperature decreasing transient state is set (S34).

[0040] On the other hand, if it is determined in S31 that the spindle cooling device 7 is stopped, the time measured up to that point is also compared with a preset delay time (S35). As a result of comparing the measured time with the delay time, if the measured time is longer than the delay time, it is determined that the cooling state of the spindle unit 4 is a heating stable state after the delay time or more has elapsed since the spindle cooling device 7 was stopped. Then, as the estimation model, an estimation model C preset to correspond to the heating stable state is set (S36). On the other hand, if the measured time is shorter than the delay time, it is determined that the cooling state of the spindle unit 4 is a temperature rise transient state from the stop of the spindle cooling device 7 until the delay time has elapsed. Then, as the estimation model, an estimation model D preset to correspond to the temperature rise transient state is set (S37).

[0041] After the estimation model is set, it is determined whether or not to continue to control the operation of the spindle cooling device (S38). If it is to be continued, the process is restarted from measuring the temperature by the temperature sensors 13, 14 (S22). The above process is carried out at preset time intervals t.

[0042] As described above, the temperature difference between the inner and outer rings Δθab that occurs in the spindle unit 4, which is the object to be cooled, due to the operation or stop of the spindle cooling device 7 during the operation of the machining center 6 nWhen estimating, an estimation model corresponding to the cooling state of the spindle unit 4, which changes depending on whether the spindle cooling device 7 is operated or stopped, is selected, so that the temperature difference between the inner and outer rings Δθab n Therefore, the estimated inner and outer ring temperature difference Δθab n It is possible to control the spindle cooling device 7 in accordance with the temperature and stabilize the temperature of the spindle unit 4 during operation, thereby preventing problems such as the spindle unit 4 burning out.

[0043] The present invention has been described above based on the illustrated examples, and the technical scope is not limited thereto. For example, as a predetermined location for which a temperature rise is estimated, thermal displacement correction is performed, and a cooling device for cooling the location is controlled, any location may be set, such as a spindle unit or a spindle, other rotating shaft, column, etc., that generates heat due to machine operation and requires thermal displacement correction or cooling. Furthermore, the temperature setting device, the correction amount calculation device, the temperature difference calculation device, and the cooling capacity setting device may be provided as separate devices, or may exist as part of the functions of the NC device. In addition, the coefficients and functions included in the estimation model are arbitrarily set so that the estimated temperature rise value of the predetermined part can be calculated from appropriate temperature data according to the type and cooling state of the predetermined part. Regarding the calculation of the estimated temperature rise value, any calculation method can be selected as long as the accurate temperature rise value of the predetermined part can be estimated from the acquired temperature data. Furthermore, the delay time used when selecting an estimation model may be calculated and determined in addition to being determined by testing or the like. For example, the delay time used when selecting an estimation model related to a rotating shaft may be calculated from the rotation speed of the rotating shaft using an arbitrary function such as T=P+QN, where T is the delay time, N is the shaft rotation speed, and P and Q are coefficients. Furthermore, the outer ring side temperature rise value Δθb n Absolute value of the difference from the previous processing time |Δθb n -Δθab n-1The delay time may be the time until | becomes greater than a threshold value determined in advance by testing, etc. Furthermore, instead of the outer ring side temperature rise value, the absolute value of the difference from the previous processing time for the estimated inner ring side temperature rise value or the estimated inner / outer ring temperature difference may be calculated, and the delay time may be the time until the calculated absolute value becomes greater than a threshold value. In addition, the cooling capacity setting device may determine what kind of command to send to the cooling device by comparing the outer ring side temperature rise value with a preset threshold value, other than comparing the estimated inner / outer ring temperature difference with a threshold value.Furthermore, for example, a temperature sensor may be provided near the motor of the spindle to measure the motor temperature, and the motor temperature rise Δθc may be compared with a preset threshold value.Furthermore, the determination may be made by combining a plurality of comparison results. [Explanation of symbols]

[0044] 3··Spindle, 4··Spindle unit (designated location, bearing), 7··Spindle cooling device (cooling device), 13,14··Temperature sensor.

Claims

1. In a machine tool equipped with a cooling device capable of cooling a specific portion that generates heat during operation of the machine, A plurality of temperature sensors are provided at any positions including a position where the temperature of the aircraft body can be measured and a position where the temperature of the predetermined portion can be measured, determining whether the cooling device is in an operating state or a stopped state, and determining whether a time measured from the start or stop of the cooling device has elapsed a preset delay time, thereby determining the cooling state of the predetermined portion; selecting an appropriate estimation model corresponding to the determined cooling state of the predetermined portion from a plurality of estimation models preset to correspond to different cooling states of the predetermined portion; A method for estimating a temperature rise value of a machine tool, comprising the steps of: calculating an estimated temperature rise value of the specified portion based on the selected estimation model and temperature data derived from measurement values ​​obtained by a plurality of the temperature sensors.

2. 2. The method for estimating a temperature rise value of a machine tool according to claim 1, further comprising determining whether the cooling state of the specified portion is in one of at least four states: a temperature decreasing transient state from when the cooling device is operated until the delay time has elapsed, a temperature increasing transient state from when the cooling device is stopped until the delay time has elapsed, a cooling stable state after the cooling device is operated and the delay time has elapsed, or a heating stable state after the cooling device is stopped and the delay time has elapsed.

3. 3. The method for estimating a temperature rise value of a machine tool according to claim 1, wherein the delay time is calculated from a value obtained based on the operation of the predetermined location by using a predetermined function.

4. 3. The method for estimating a temperature rise value of a machine tool according to claim 1 or 2, characterized in that the delay time is determined by calculating a change per unit time for at least one of the temperature data and the estimated temperature rise value at the specified location, and determining the time until the calculated change per unit time becomes greater than a preset threshold value.

5. In a machine tool equipped with a cooling device capable of cooling a specific portion that generates heat during operation of the machine, A plurality of temperature sensors are provided at any positions including a position where the temperature of the aircraft body can be measured and a position where the temperature of the predetermined portion can be measured, determining whether the cooling device is in an operating state or a stopped state, and determining whether a time measured from the start or stop of the cooling device has elapsed a preset delay time, thereby determining the cooling state of the predetermined portion; selecting an appropriate estimation model corresponding to the determined cooling state of the predetermined portion from a plurality of estimation models preset to correspond to different cooling states of the predetermined portion; Calculating an estimated temperature rise value of the predetermined portion based on the selected estimation model and temperature data derived from measured values ​​acquired by the plurality of temperature sensors; A method for estimating a thermal displacement amount of a specified part, comprising: estimating a thermal displacement amount of the specified part using the calculated estimated temperature rise value of the specified part and a coefficient for converting the temperature rise value of the specified part into a thermal displacement amount, based on the selected estimation model.

6. 6. The method for estimating a thermal displacement of a machine tool according to claim 5, further comprising determining whether the cooling state of the specified portion is in one of at least four states: a temperature decreasing transient state from when the cooling device is operated until the delay time has elapsed, a temperature increasing transient state from when the cooling device is stopped until the delay time has elapsed, a stable cooling state after the cooling device is operated and the delay time has elapsed, or a stable heating state after the cooling device is stopped and the delay time has elapsed.

7. 7. The method for estimating a thermal displacement of a machine tool according to claim 5, wherein the delay time is calculated from a value obtained based on the operation of the predetermined location by using a predetermined function.

8. The method for estimating a thermal displacement of a machine tool according to claim 5 or 6, characterized in that the delay time is determined by calculating a change per unit time for at least one of the temperature data and the estimated temperature rise value at the specified location, and determining the time until the calculated change per unit time becomes greater than a preset threshold value.

9. A machine tool having a rotating shaft and a cooling device having a path for cooling at least an outer ring side of a bearing of the rotating shaft, A plurality of temperature sensors are provided at arbitrary positions including a position where at least a machine body temperature can be measured and a position where a temperature of an outer ring side of the bearing can be measured, determining whether the cooling device is in an operating state or a stopped state, and determining whether a time measured from the operating or stopped state of the cooling device has elapsed a preset delay time, thereby determining the state of the bearing; selecting an appropriate estimation model corresponding to the determined cooling state of the bearing from a plurality of estimation models preset to correspond to different cooling states of the bearing; calculating an estimated temperature rise value of the inner ring side of the bearing using coefficients based on the selected estimation model and temperature data derived from measured values ​​acquired by the plurality of temperature sensors; calculating an estimated inner / outer ring temperature difference from the calculated estimated temperature rise value of the inner ring side of the bearing and a temperature rise value of the outer ring side of the bearing calculated based on the temperature data derived from the measurement value obtained from the temperature sensor that measures the temperature of the outer ring side of the bearing; A method for controlling a bearing cooling device of a machine tool, characterized in that the cooling device is started or stopped when the estimated inner / outer ring temperature difference exceeds or falls below a predetermined threshold based on the selected estimation model.

10. 10. The method for controlling a bearing cooling device of a machine tool according to claim 9, further comprising determining whether the cooling state of the bearing is in one of at least four states: a temperature decreasing transient state from when the cooling device is operated until the delay time has elapsed, a temperature increasing transient state from when the cooling device is stopped until the delay time has elapsed, a stable cooling state after the cooling device is operated and the delay time has elapsed, or a stable heating state after the cooling device is stopped and the delay time has elapsed.

11. 11. The method for controlling a bearing cooling device of a machine tool according to claim 9, wherein the delay time is calculated from the rotation speed of the rotating shaft by using a predetermined function.

12. 11. The method for controlling a bearing cooling device of a machine tool according to claim 9 or 10, characterized in that the delay time is determined by calculating a change per unit time for at least one of the temperature data, the estimated temperature rise value on the inner ring side of the bearing, and the estimated inner / outer ring temperature difference, and determining the time until the calculated change per unit time becomes greater than a preset threshold value.

13. A machine tool equipped with a cooling device capable of cooling a predetermined portion that generates heat during operation of the machine, A plurality of temperature sensors are provided at any positions including a position where the temperature of the aircraft body can be measured and a position where the temperature of the predetermined portion can be measured, determining whether the cooling device is in an operating state or a stopped state, and determining whether a time measured from the start or stop of the cooling device has elapsed a preset delay time, thereby determining the state of the predetermined portion; selecting an appropriate estimation model corresponding to the determined cooling state of the predetermined portion from a plurality of estimation models preset to correspond to different cooling states of the predetermined portion; A machine tool comprising a device for calculating an estimated temperature rise value of the specified portion based on the selected estimation model and temperature data derived from measurement values ​​obtained by the multiple temperature sensors.

14. 14. The machine tool according to claim 13, characterized in that it determines whether the cooling state of the specified portion is one of at least four states: a temperature decreasing transient state from when the cooling device is operated until the delay time has elapsed, a temperature increasing transient state from when the cooling device is stopped until the delay time has elapsed, a cooling stable state after the cooling device is operated and the delay time has elapsed, or a heating stable state after the cooling device is stopped and the delay time has elapsed.

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