JP2004276145A - Machine tool and mounting abnormality determination method of tool holder in device having rotating shaft - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a machine tool, simply and surely detecting a chuck error to prevent the generation of defective. <P>SOLUTION: In this machine tool, a tool holder to which a tool is fitted is mounted on a spindle 1, and the spindle is driven to rotate, thereby machining a work. The machine tool includes: a sensor 12 measuring the displacement of the outer peripheral surface of a flange 2B of the tool holder 2 mounted on the spindle 1 and a chuck error detecting device 10 formed of a data processor for determining the abnormality of mounting state of the tool holder 2 to the spindle 1 from the measurement data obtained by the sensor 12. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for determining an abnormal mounting state of a tool holder in a machine tool and an apparatus having a rotating shaft, and more particularly to a tool holder in a machine tool using a tool holder such as a machining center (hereinafter abbreviated as “MC”). The present invention relates to a machine tool capable of automatically detecting an abnormality in a mounting state of a tool holder on a spindle, and a method of determining a mounting state abnormality of a tool holder in an apparatus having a rotating shaft.
[0002]
[Prior art]
The MC is a device that automatically selects various tools according to a machining process, and automatically mounts them on a spindle to perform various types of machining. In this MC, tool change is performed by an automatic tool change (ATC: auto tool holder change) device. This ATC device is a device for automatically taking out a tool holder on which a tool is mounted from a tool magazine and automatically mounting the tool holder on a spindle.
[0003]
FIG. 14 is a cross-sectional view showing a state where the tool holder 2 is mounted on the main shaft 1. As shown in the figure, the tool holder 2 has a conical fitting portion 2A, and the fitting portion 2A is fitted to a conical fitting portion 1A formed on the main shaft 1. Is attached.
[0004]
The procedure is as follows. By pulling the shaft 3 to the right, the ball holder 4 and the ball 5 move accordingly. The movement of the ball 5 pulls the pull stud (drawing bolt) 6, whereby the conical fitting portion 2A of the tool holder 2 is pressed against the conical fitting portion 1A of the main shaft 1. Due to the pressed pressure, the fitting portion 2A comes into close contact with the fitted portion 1A, and mounting (chucking) with high accuracy is performed.
[0005]
FIG. 15 is an explanatory diagram illustrating a mounted state of the tool holder 2 that holds the tool T. Normally, the tool holder 2 is properly mounted, and the state shown in FIG. However, as shown in FIG. 2B, if chips 7 or the like adhere to this fitting portion, the shaft is bent and mounted. When machining is performed in this state, the tool T has runout, and there is a disadvantage that machining accuracy of the workpiece is significantly reduced. As a technique for automatically detecting the presence or absence of such a chuck error of the tool holder, a proposal by the present applicant has been made (see Patent Document 1).
[0006]
[Patent Document 1]
JP-A-2002-200542
[0007]
[Problems to be solved by the invention]
However, besides the above-described chuck error, a phenomenon that causes an abnormality in a mounting state of the tool holder to the main spindle is occasionally observed. This phenomenon is often seen after about two years of operation after a new MC is delivered. The frequency is about once a month.
[0008]
As a phenomenon, it has been confirmed that the pulling force of a pull stud (drawing bolt), which is usually about 2 tons, is reduced to about 0.8 tons for some reason, which causes an abnormal mounting state of the tool holder. The cause of this is presumed to be a deterioration of the mounting mechanism, such as a set of a disc spring (not shown) in the mounting portion of the tool holder 2 to the main shaft 1 or a decrease in grip force, but the details are unknown. There is at present.
[0009]
That is, at present, when the processing accuracy of the work is reduced, it is difficult to determine that the cause is a decrease in the clamping force of the tool holder in view of the frequency.
[0010]
Therefore, the only way to deal with such an abnormality in the mounting state is to replace parts around the spindle 1 with new ones. Also, in order to prevent such an abnormal mounting state from occurring, the total operation time, the transition of the machining accuracy of the work, etc. are checked in advance, and the parts around the spindle 1 are replaced with new parts as soon as possible. I was Due to such inconveniences, there has been a strong demand for an improvement with respect to a poor clamping force of the tool holder.
[0011]
The present invention has been made in view of such circumstances, and an object of the present invention is to provide a machine tool that can easily and surely detect a chuck error and thereby eliminate the occurrence of defective products.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a machine tool that mounts a tool holder on which a tool is mounted on a main spindle and rotationally drives the main spindle to process a workpiece, wherein a flange outer periphery of the tool holder mounted on the main spindle is provided. A machining tool comprising: a measuring means for measuring a displacement of a surface; and a mounting state determining means for determining an abnormality in a mounting state of the tool holder to the spindle from measurement data obtained by the measuring means. Provide the machine.
[0013]
According to the present invention, the displacement of the outer peripheral surface of the flange of the tool holder mounted on the spindle is measured, and an abnormality in the mounted state is determined from the measured data. Thereby, the chuck error of the tool holder can be reliably detected, and the occurrence of defective products can be eliminated.
[0014]
That is, the present inventor has found that there is a correlation between the chuck error due to the poor clamping force of the tool holder and the displacement of the outer peripheral surface of the tool holder, and by measuring the displacement of the outer peripheral surface of the tool holder, the chuck of the tool holder is determined. A means to detect errors has been introduced. Since this detection can be performed in real time in the processing cycle and before processing the work, it is possible to avoid the occurrence of a defective work.
[0015]
In the present specification, the problem described in Patent Document 1 is referred to as “chuck error”, and the problem according to the present invention is referred to as “chuck error” (abnormal mounting state).
[0016]
In the present invention, it is preferable that the machine tool can automatically take out the tool holder from a tool magazine and mount the tool holder on a spindle. This is because the productivity is improved by combining the tool holder and the tool magazine.
[0017]
Further, in the present invention, the basic data storage means for storing measurement data of the displacement of the flange outer peripheral surface of the tool holder mounted on the spindle as basic data, and the basic data and the measurement data measured by the measurement means. True measurement data calculating means for comparing and calculating true measurement data, wherein the mounting state determination means calculates the spindle of the tool holder from the true measurement data calculated by the true measurement data calculation means. It is preferable to determine an abnormality in the state of attachment to the device.
[0018]
In this manner, if the configuration is such that the true measurement data is obtained by comparing the basic data and the measurement data, the accuracy of determining the abnormality of the mounting state of the tool holder on the spindle is improved.
[0019]
Further, in the present invention, the measuring means includes a distance measuring means for measuring a distance from a predetermined measuring point to a flange outer peripheral surface of the tool holder, and a measuring means for measuring the distance corresponding to a rotation angle of the tool holder. And measurement data storage means for storing data.
[0020]
Further, in the present invention, it is preferable to include a calculation means for performing Fourier analysis on the measurement data and extracting a fundamental frequency component. This is because the measurement accuracy is improved by using such an arithmetic unit.
[0021]
Further, in the present invention, it is preferable that the apparatus further includes a determination unit that performs a Fourier analysis on the measurement data, and determines an abnormality in a mounting state of the tool holder to the spindle based on a power spectrum shape of the analysis result. This is because the measurement accuracy is improved by using such a determination unit.
[0022]
Further, in the present invention, when a notch is formed on the outer peripheral surface of the flange of the tool holder, it is preferable to supplement data of the notch portion of the measurement data. This is because a tool holder in which a notch is formed on the outer peripheral surface of the flange is generally used, and if data of the notch can be complemented, measurement accuracy is improved.
[0023]
In the present invention, it is preferable that the distance measuring means is an eddy current sensor. This is because such a distance measuring means can obtain a highly accurate measurement result even in an environment where coolant (cutting fluid) or the like scatters.
[0024]
Further, in the present invention, it is preferable that the mounting state determination unit determines whether the mounting state is appropriate by comparing an eccentric amount immediately after the rotation of the tool holder is started and an eccentric amount after a predetermined time has elapsed. The inventor of the present application has found that when the tool holder is not properly mounted, the amount of eccentricity is large immediately after the start of rotation of the tool holder, and thereafter, the amount of eccentricity returns to normal after a predetermined time has elapsed. Therefore, by making such a determination, it is possible to reliably determine whether or not the mounted state of the tool holder is appropriate.
[0025]
The present invention also provides a device for mounting a tool holder on a shaft and rotating the shaft, measuring displacement of an outer peripheral surface of a flange of the tool holder, thereby obtaining an eccentric amount of the tool holder, A tool holder in an apparatus having a rotating shaft, wherein an abnormality in a mounting state of the tool holder to the shaft is determined by comparing the amount of eccentricity immediately after the start of rotation with the amount of eccentricity after a predetermined time has elapsed. Provided is a method for determining a wearing state abnormality.
[0026]
By applying the above-described configurations of the present invention, it is possible to determine an abnormality in the mounted state of the tool holder even in various devices having a rotating shaft other than the machine tool.
[0027]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of a machine tool according to the present invention will be described in detail with reference to the accompanying drawings.
[0028]
FIG. 1 is a block diagram showing a first embodiment of a chuck error detecting device incorporated in a machine tool according to the present invention. The chuck error detecting device 10 is a device for automatically detecting a chuck error (attachment state abnormality) of the tool holder 2 attached to the spindle 1 by the ATC device, and mainly includes a sensor 12 as a measuring unit and an attachment state determining unit. And a certain data processing device 14.
[0029]
The sensor 12 is attached via a bracket 6 to the head 5 to which the main shaft 1 is attached. The sensor 12 is an eddy current sensor, and detects a distance d to the outer peripheral surface of the flange portion 2B of the tool holder 2 mounted on the main shaft 1 as an electric signal.
[0030]
The data processing device 14 detects a chuck error of the tool holder 2 based on measurement data measured by the sensor 12, and includes an A / D converter 16, a CPU 18, a memory 20, an input / output circuit 22, and the like.
[0031]
The A / D converter 16 converts an electric signal indicating the distance d output from the sensor 12 into a digital signal and outputs the digital signal to the CPU 18. The CPU 18 calculates the amount of eccentricity of the tool holder 2 based on the measurement data of the sensor 12 converted into the digital signal. Then, the calculated eccentricity is compared with a threshold value stored in the memory 20 in advance. If the change in the amount of eccentricity exceeds the threshold, it is determined that a chuck error has occurred. Then, the result is output to the MC control device 24 that controls the MC via the input / output circuit 22. The details will be described later.
[0032]
As described above, the CPU 18 calculates the amount of eccentricity of the tool holder 2 based on the measurement data of the distance d measured by the sensor 12, and this calculation process and the determination of the mounting state of the tool holder 2 are performed as follows. .
[0033]
First, the CPU 18 receives a measurement start command from the MC control device 24 via the input / output circuit 22. Then, the measurement data of the distance d output from the sensor 12 is stored in the memory 20 in correspondence with the rotation angle θ of the tool holder 2. This measurement is performed for two rotations of the tool holder immediately after the start of rotation. Of these, the measurement data of the distance d for the first round of the tool holder is displayed as a graph, for example, as shown in FIG.
[0034]
Next, the CPU 18 performs the FFT analysis on the measurement data of the distance d for the first round of the tool holder stored in the memory 20. That is, the measurement data for one round of the tool holder is subjected to Fourier analysis to be decomposed into components of each frequency.
[0035]
Note that the FFT analysis may be performed simultaneously with the measurement. When the result of the FFT analysis is displayed as a power spectrum, for example, the result is as shown in FIG.
[0036]
Here, among the frequency components subjected to the FFT analysis as described above, the amplitude value of the fundamental frequency component (one peak component) can be regarded as twice the amount of eccentricity of the tool holder 2. , The amplitude of the fundamental frequency component is calculated, and the eccentric amount T of the first rotation of the tool holder 2 is calculated. ₁ To get.
[0037]
The same measurement as above is performed for the second rotation of the tool holder immediately after the start of rotation. As a result, the eccentricity T of the tool holder 2 in the second round is ₂ To get.
[0038]
Then, the obtained eccentric amount T ₁ And T ₂ Is determined on the basis of. Specifically, the amount of eccentricity T ₁ And eccentricity T ₂ The presence / absence of a chuck error is determined based on whether or not the difference from is greater than or equal to a predetermined threshold. If the difference is equal to or greater than the threshold value, it is determined that a chuck error has occurred, and if the difference is less than the threshold value, it is determined that the error is normal. This predetermined threshold is determined by the specifications of the MC and the like. This determination was introduced by the inventor of the present application because he discovered the phenomenon described below.
[0039]
That is, irrespective of the chuck error of the tool holder 2, the eccentric amount T of the first rotation immediately after the rotation of the tool holder 2 is started. ₁ Is big. On the other hand, the eccentric amount T in the second rotation of the tool holder 2 without chuck error ₂ Is a small value. On the other hand, the eccentric amount T of the second rotation of the tool holder 2 in which a chuck error has occurred ₂ Is the eccentricity T of the first lap ₁ , But sufficiently larger than the value without chuck error.
[0040]
This phenomenon will be described with reference to the amount of eccentricity measured using a specific MC. FIG. 16 is a table showing the amount of eccentricity of the tool holder in each state of the MC. In the table, "normal" means that there is no chuck error, "abnormal" means that a chuck error occurs, and "NG" means that the mechanism around the spindle is in a state requiring replacement. Also, T _m Indicates the amount of eccentricity at the time of processing a workpiece. The figures of the amount of eccentricity in the table indicate the approximate order, and fine values are rounded.
[0041]
In a normal state, the eccentricity T ₁ Is 10 μm, T ₂ Is 2 μm, T _m Is at the level of 1 μm. On the other hand, in an abnormal state, the eccentricity T ₁ Is 100 μm, T ₂ Is as large as 10 μm, and T _m Is at a level of 1 μm as in the normal state. In the case of the NG state, the eccentricity T ₁ Is 100 μm, T ₂ Is 50 μm, T _m Is as large as 30 μm.
[0042]
Thus, the amount of eccentricity T ₁ And eccentricity T ₂ By observing the difference between the two, the presence or absence of a chuck error can be determined. Similarly, the amount of eccentricity T ₁ And eccentricity T ₂ T which is the ratio of ₁ / T ₂ Can be determined by checking the extent of the chuck error.
[0043]
In the above example, the eccentric amount T of the first rotation of the tool holder 2 is used. ₁ And the eccentricity T of the second lap ₂ , But depending on the device, T ₂ Of eccentricity T in the third round of tool holder 2 in place of ₃ Or the eccentricity T of the fourth lap ₄ In some cases, it may be easier to determine the presence or absence of a chuck error by using. Therefore, the suitability of the mounting state may be determined by comparing the amount of eccentricity immediately after the start of rotation of the tool holder and the amount of eccentricity after the elapse of a predetermined time in accordance with the device characteristics.
[0044]
Further, a method of performing a statistical process such as calculating a standard deviation of the eccentric amount for several rounds of the tool holder 2 and determining whether or not the mounted state is appropriate based on the result may be adopted.
[0045]
Next, a method of detecting a chuck error of the tool holder 2 by the chuck error detection device 10 according to the present embodiment configured as described above will be described with reference to a flowchart shown in FIG.
[0046]
The chuck error detection device 10 is started when the operation of the MC starts (step S1). When the tool exchange (ATC) is performed by the ATC device (Step S2), the MC control device 24 rotates the spindle at a preset rotation speed (Step S3).
[0047]
The sensor 12 measures a distance d to the outer peripheral surface of the rotating flange 2B of the tool holder 2. The CPU 18 stores the measurement data of the distance d measured by the sensor 12 in the memory 20 in correspondence with the rotation angle θ of the tool holder 2.
[0048]
The measurement is performed for two rounds immediately after the start of rotation of the tool holder 2 (steps S4 and S7), and this measurement data is obtained.
[0049]
The CPU 18 performs FFT analysis on the measurement data stored in the memory 20, extracts one peak component, and calculates its amplitude value. Since the amplitude value of this one peak component is equal to twice the eccentric amount T of the tool holder 2, the eccentric amount T of the tool holder 2 is thereby set. ₁ , T ₂ Is obtained (steps S6 and S8). The CPU 18 calculates the obtained eccentricity T ₁ And T ₂ Is compared with a predetermined threshold to determine whether there is a chuck error (step S9).
[0050]
The FFT analysis may be performed simultaneously with the measurement. Further, the predetermined threshold value is input by an operator from an input device (not shown) before the operation of the MC is started. The input predetermined threshold value is stored in the memory 20. Also, the predetermined threshold is appropriately selected and set based on the processing accuracy required by the user.
[0051]
The determination result is output to the MC control device 24. When the MC control device 24 determines that the state is normal without chuck error (the eccentric amount T ₁ And T ₂ In the case of the difference <threshold value> (step S10), the processing is directly started (step S11). On the other hand, when a chuck error is determined (the eccentricity T ₁ And T ₂ (Difference ≧ threshold) (step S12), a command is issued to display that effect on a display unit (not shown) of the MC control device 24 (or to sound an alarm or blink a patrol light) (step S12). S13).
[0052]
As described above, according to the chuck error detection device 10 of the present embodiment, the eccentricity of the tool holder 2 is measured, and the chuck error of the tool holder 2 is detected based on the eccentricity. A chuck error of the holder 2 can be detected. Further, the device configuration is extremely simple, and complicated control is not required, so that detection can be easily performed.
[0053]
Next, a second embodiment of the machine tool according to the present invention will be described. The device used is the same as in the first embodiment.
[0054]
In the first embodiment, the flange portion 2B of the tool holder 2, which is the measurement point of the sensor 12, is circular. Generally, the flange portion 2B of the tool holder 2 is shown in FIG. Notches 2C and 2C for the chuck are often formed as described above. The chuck error detection method according to the second embodiment is a detection method when notches 2C, 2C are formed in the flange portion 2B of the tool holder 2, which is a measurement point.
[0055]
When there are two notches 2C and 2C in the flange portion 2B of the tool holder 2, the measurement data for one round of the tool holder is displayed as a graph, for example, as shown in FIG. 6A. As shown in the figure, the measurement data rapidly changes at two notches 2C and 2C. The measurement data of the notches 2C and 2C are corrected by, for example, linear interpolation. FIG. 6B is a graph showing measurement data obtained by linearly interpolating the notches 2C and 2C.
[0056]
As described above, when the notch 2C, 2C is present in the flange portion 2B of the tool holder 2 which is the measurement point of the sensor 12, the measurement data of the notch 2C, 2C is complemented, and the complemented measurement data is obtained. Is subjected to FFT analysis (FIG. 6 (c)), and one hill component is extracted to calculate the amount of eccentricity (amplitude value). Then, a chuck error is determined based on the calculation result. As a result, a chuck error can be effectively detected even for a tool holder having a notch in the flange portion.
[0057]
Next, a third embodiment of the machine tool according to the present invention will be described. The device used is the same as the device of the first embodiment.
[0058]
When an eddy current sensor is used as a sensor, the electric signal from the eddy current sensor may not be in the shape of the tool holder due to the influence of magnetization or the change in the thickness (area) of the measurement part of the tool holder. If the amount of eccentricity is calculated in this state, an error is included, and the detection accuracy may be reduced.
[0059]
Therefore, in order to perform detection with higher accuracy, a chuck error is detected by the following method. That is, as shown in FIG. 7, the amount of eccentricity of the tool holder 2 mounted without any chuck error is measured in advance, and the measured eccentric amount is regarded as a basic eccentric amount unique to the tool holder and stored. Then, the true eccentricity is calculated by comparing the basic eccentricity with the measured eccentricity measured at the time of ATC, and a chuck error is determined based on the calculated true eccentricity.
[0060]
Hereinafter, the chuck error detection method according to the third embodiment will be described with reference to the flowcharts shown in FIGS. First, setup is performed to detect the basic eccentricity (step S20). The setup is performed before starting the operation of the MC according to the flowchart shown in FIG.
[0061]
First, the tool holder 2 is mounted on the main shaft 1. Since the operation has not been started, there is no case where the cutting chips are caught, and the tool holder 2 is properly mounted on the main shaft 1. In this state, the tool holder 2 is rotated, and in a state where the rotation is sufficiently stabilized, a change in the distance d for one round of the tool holder is measured by the sensor 12 (step S21). When the measured data of the distance d for one round of the tool holder having the notch is graphically displayed, for example, it becomes as shown in FIG.
[0062]
Next, when there is a notch in the tool holder 2, as shown in FIG. 10B, the center of one of the two notches 2C and 2C becomes 0 °. The phase of the measurement data is corrected as described above (step S22). Then, as shown in FIG. 10C, the measurement data of the two notches 2C and 2C is corrected (step S23). Here, the measurement data is corrected by linear interpolation.
[0063]
If there is no notch in the tool holder 2, the process of the above-described phase correction (step S22) and notch correction (step S23) is not performed, and the process proceeds to the next process (step S24).
[0064]
Next, the measured data is subjected to FFT analysis to calculate the amplitude and phase (angle) of one peak component. Then, as shown in FIG. 12A, the eccentricity and the phase calculated from the amplitude are stored in the memory 20 as the basic eccentricity u and the basic eccentricity direction α (hereinafter referred to as “basic eccentricity vector U”). (Step S24).
[0065]
Next, as shown in FIG. 10D, a sine wave is restored from the calculated amplitude and phase of the one peak component. Then, a waveform is calculated by subtracting the restored sine wave data from the measurement data (original data) after the notch correction shown in FIG. 10C (the waveform in FIG. 10E). The calculated waveform is regarded as the pattern of the magnetic unevenness of the measured point sequence data, and is stored in the memory 20 (step S25).
[0066]
Thus, the setup operation is completed (step S26). This setup operation is performed for all the tool holders required by the user among the tool holders set in the tool magazine, and stored in the memory 20 as data unique to each tool holder.
[0067]
When the operation of the MC is started, a chuck error of the tool holder is detected according to the flowchart shown in FIG. 9 (step S30).
[0068]
When the tool is exchanged by the ATC device (step S31), the tool holder 2 mounted on the main shaft 1 starts rotating at a specified number of revolutions (step S32), and data for one round of the tool holder is measured by the sensor 12. Is performed (step S33). If there is a notch in the tool holder 2, the notch correction is performed on the measurement data (step S34), and then a magnetic concavo-convex pattern is obtained (step S35). When there is no notch in the tool holder 2, the notch correction processing (step S34) is unnecessary.
[0069]
The method of acquiring the measurement data and the method of correcting the notch when the tool holder 2 has a notch are the same as those in the first and second embodiments. The method for obtaining the pattern is the same as in the setup described above.
[0070]
Next, as shown in FIG. 11, the calculated magnetic concavo-convex pattern (processing magnetic pattern) is compared with the set-up magnetic concavo-convex pattern stored in the memory 20 (setup magnetic pattern). It is determined which of the calculated magnetic concavo-convex patterns is located at 0 ° (step S36).
[0071]
If there is a notch in the tool holder 2, it is determined here which of the two notches 2C, 2C is located at 0 °. Then, the phase of the notch-corrected measurement data is corrected so that the determined position becomes 0 ° (step S37).
[0072]
Next, the phase-corrected measurement data is subjected to FFT analysis to calculate the amplitude and phase of one peak component. Then, as shown in FIG. 12B, the eccentricity and phase calculated from the amplitude are stored in the memory 20 as the measured eccentricity v and the measured eccentricity direction β (hereinafter, referred to as “measured eccentricity vector V”). (Step S38).
[0073]
Next, as shown in FIG. 12C, the difference between the calculated measured eccentricity vector V and the basic eccentricity vector U stored in the memory 20 is calculated by a vector operation (step S39). Then, the calculated vector is used as a true eccentric vector R, and the magnitude r of the true eccentric vector R is obtained. ₁ (Step S40).
[0074]
The same measurement (steps S33 to S40) is performed for the second lap (or third lap, fourth lap, etc.) of the tool holder 2, and the true lap of the second lap (or third lap, fourth lap, etc.) is performed. Eccentricity r ₂ Is obtained (step S41). The CPU 18 calculates the true eccentricity r ₁ And r ₂ Is compared with a predetermined threshold to determine the presence or absence of a chuck error (step S42).
[0075]
The determination result is output to the MC control device 24. When the MC control device 24 determines that the state is a normal state with no chuck error (the true eccentricity r ₁ And r ₂ In step S43, the processing is started as it is (step S44). On the other hand, when a chuck error is determined (the true eccentricity r ₁ And r ₂ For (difference ≧ threshold) (step S45), a command is issued to display that effect on a display unit (not shown) of the MC control device 24 (or to sound an alarm or blink a patrol light) (step S45). S46).
[0076]
As described above, in the chuck error detection method according to the present embodiment, the chuck error is determined based on the true eccentric amount r from which the eccentric amount unique to the tool holder is removed. Detection can be performed. In the present embodiment, since the eccentric direction can be specified from the true eccentric vector R, it is convenient to specify an abnormal point on the apparatus.
[0077]
As mentioned above, although the example of the embodiment of the machine tool concerning the present invention was explained, the present invention is not limited to the example of the above-mentioned embodiment, but can take various aspects. For example, in the above-described series of embodiments, the eddy current sensor is used as the sensor 12, but the sensor is not limited to the eddy current sensor as long as it can measure the distance from a specific measurement point to the outer peripheral surface of the tool holder 2. , Other sensors may be used. In this case, the present invention is not limited to a non-contact type sensor such as an eddy current sensor, and a contact type sensor may be used.
[0078]
In addition, in the above-described series of embodiments, when the CPU 18 determines that a chuck error has occurred, an error display is instructed to the display unit of the MC. However, as shown in FIG. It is also possible to adopt a form that can be distinguished from a chuck error of the tool holder due to the chip 7 or the like adhering to the joint portion.
[0079]
That is, the CPU 18 determines that a chuck error should be determined (the amount of eccentricity T ₁ And T ₂ First, the ATC is performed again, and the same measurement is performed again. Based on the result, it can be determined whether the error is a chuck error due to the device or a chuck error due to the attachment of the chip 7 or the like to the fitting portion, and errors are less likely to occur in the subsequent measures.
[0080]
Further, in the present embodiment, the displacement of the outer periphery of the tool holder is measured, the measured data is subjected to FFT analysis to extract one peak component, and the amplitude value thereof is obtained, thereby obtaining the amount of eccentricity. However, the method of obtaining the amount of eccentricity is not limited to this method.
[0081]
Further, in the present embodiment, the eccentricity is obtained by performing an FFT analysis on the measurement data to extract one peak component, and obtaining the amplitude value, but the maximum value and the minimum value of the measurement data are determined. Alternatively, the eccentricity of the tool holder may be obtained by calculating the eccentricity from the difference.
[0082]
Similarly, the presence or absence of a chuck error can be determined by detecting an abnormality in the amplitude value of a peak component other than the one peak component obtained by the FFT analysis. Also, the presence or absence of a chuck error can be determined by comprehensively determining the amplitude values of a plurality of mountain components obtained by FFT analysis.
[0083]
Further, in the present embodiment, the flange portion 2B of the tool holder 2 is used as a measurement point of the sensor 12, but the measurement point of the sensor 12 is not limited to this, and depends on the measurement situation and the like. It may be changed as appropriate. For example, as shown in FIG. 13, the cutting edge of the tool T (the point where the workpiece is cut) may be set as the measurement point. As described above, by setting the cutting edge of the tool T as a measurement point, the eccentricity of a portion to be directly machined can be measured, so that a chuck error can be more reliably detected.
[0084]
Further, in the present embodiment, the sensor 12 is attached to the head 5, but the installation location of the sensor 12 is not limited to this, and the sensor 12 may be attached to a location other than the head 5. For example, the sensor 12 may be fixed to a predetermined position other than the head 5, and the head 5 may be moved to the measurement position of the sensor 12 to detect a chuck error. The position of the sensor 12 other than the head may be set, for example, at the first origin of the MC (a reference point (starting point) on the coordinates where the head 5 is always located during machining) or at any other position. Can be. In this case, in order to secure more stable and accurate measurement, it is preferable that the sensor 12 is installed at a position not affected by the coolant (a position where the coolant is not applied).
[0085]
Further, in the present embodiment, an example in which the present invention is applied to an MC has been described. However, the present invention is not limited to the MC, and can be applied to any machine tool using an ATC device.
[0086]
In the above-described series of embodiments, the eccentricity of the tool holder mounted on the spindle is measured, and the chuck error is detected based on the eccentricity. The deflection of the tool is measured by measuring the amount of eccentricity of the tool holder.
[0087]
【The invention's effect】
As described above, according to the present invention, the displacement of the outer peripheral surface of the flange of the tool holder mounted on the spindle is measured, and an abnormality in the mounted state is determined from the measured data. This makes it possible to reliably detect a chuck error (abnormal mounting state) of the tool holder and eliminate defective products.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a first embodiment of a chuck error detection device.
FIG. 2 is a graph of measurement data for one round of a tool holder.
FIG. 3 is a graph showing a power spectrum of the result of FFT analysis.
FIG. 4 is a flowchart illustrating a processing procedure of a chuck error detection method according to the first embodiment;
FIG. 5 is a plan view of a tool holder having a notch in a flange portion.
6A is a graph of measured data of a tool holder having a notch in a flange portion, FIG. 6B is a graph of corrected measured data, and FIG. 6C is a graph showing a power spectrum of an FFT analysis result.
FIG. 7 is a conceptual diagram of a chuck error detection method according to a third embodiment.
FIG. 8 is a flowchart at the time of setup.
FIG. 9 is a flowchart at the time of detection.
10A is a graph of measurement data for one rotation of a tool holder mounted without a chuck error, FIG. 10B is a graph of measurement data with phase correction, and FIG. 10C is measurement data with notch correction (D) is a graph showing a restored sine wave, and (e) is a graph showing a magnetic concavo-convex pattern.
FIG. 11 is a conceptual diagram at the time of phase correction.
FIG. 12 is a conceptual diagram of a vector operation.
FIG. 13 is a block diagram showing another embodiment of the chuck error detection device.
FIG. 14 is a sectional view showing a mounted state of the tool holder.
FIG. 15 is an explanatory view showing a mounted state of a tool holder.
FIG. 16 is a table showing the amount of eccentricity of the tool holder in each state of the MC.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Spindle, 1A ... Fitting part, 2 ... Tool holder, 2A ... Fitting part, 2B ... Flange part, 2C ... Notch, 7 ... Chipping, 10 ... Chuck error detection device, 12 ... Sensor, 14 ... Data processing device, 16 A / D converter, 18 CPU, 20 memory, 22 input / output circuit, 24 MC controller, d distance, θ rotation angle, U basic eccentricity vector, u basic eccentricity Amount, α: basic eccentric direction, V: measured eccentric vector, v: measured eccentric amount, β: measured eccentric direction β, R: true eccentric vector, r: true eccentric amount, T: tool

Claims (9)

In a machine tool that mounts a tool holder with a tool attached to a main spindle and rotationally drives the main spindle to process a workpiece,
Measuring means for measuring the displacement of the outer peripheral surface of the flange of the tool holder attached to the spindle,
Mounting state determination means for determining an abnormality in the mounting state of the tool holder to the spindle from the measurement data obtained by the measurement means,
A machine tool comprising: Basic data storage means for storing measurement data of the displacement of the flange outer peripheral surface of the tool holder mounted on the spindle as basic data,
True measurement data calculation means for calculating true measurement data by comparing the basic data and measurement data measured by the measurement means,
With
The work according to claim 1, wherein the mounting state determination unit determines an abnormality in a mounting state of the tool holder to the spindle from the true measurement data calculated by the true measurement data calculation unit. machine. The measuring means comprises:
Distance measuring means for measuring a distance from a predetermined measurement point to the outer peripheral surface of the flange of the tool holder,
Measurement data storage means for storing measurement data of the distance measurement means in correspondence with the rotation angle of the tool holder;
The machine tool according to claim 1, comprising: The machine tool according to any one of claims 1 to 3, further comprising a calculation unit configured to perform a Fourier analysis on the measurement data and extract a fundamental frequency component. 4. The apparatus according to claim 1, further comprising: a determination unit configured to perform a Fourier analysis on the measurement data and determine an abnormality in a mounting state of the tool holder to the spindle from a power spectrum shape of the analysis result. 5. The machine tool according to claim 1. The machine tool according to any one of claims 1 to 5, wherein when the notch is formed on the outer peripheral surface of the flange of the tool holder, data of the notch portion of the measurement data is complemented. The machine tool according to claim 1, wherein the distance measuring unit is an eddy current sensor. 8. The apparatus according to claim 1, wherein the mounting state determining unit determines whether the mounting state is appropriate by comparing an eccentric amount immediately after the rotation of the tool holder is started and an eccentric amount after a predetermined time has elapsed. 2. The machine tool according to claim 1. In a device in which a tool holder is mounted on a shaft and the shaft is rotationally driven,
Measure the displacement of the flange outer peripheral surface of the tool holder, thereby determining the amount of eccentricity of the tool holder,
An apparatus having a rotating shaft, wherein an abnormality in a mounting state of the tool holder to the shaft is determined by comparing an eccentric amount immediately after the start of rotation of the tool holder and an eccentric amount after a predetermined time has elapsed. Tool holder mounting state abnormality judgment method.

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