JP2017067670A - Displacement measurement device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a displacement measurement device which, even if simple and small-sized, has good accuracy and sensitivity when measuring displacement between an eddy current type displacement sensor and a measurement object, especially to provide a displacement measurement device that improves measurement accuracy or measurement sensitivity with regard to displacement between the eddy current type displacement sensor and the measurement object by improving measurement accuracy or sensitivity with regard to the oscillation frequency of a voltage waveform supplied by the eddy current type displacement sensor.SOLUTION: The displacement measurement device comprises: an eddy current type displacement sensor for supplying a first voltage waveform whose oscillation frequency changes in correspondence to displacement between the voltage value of a control voltage and a measurement object; and a frequency conversion unit for generating a second voltage waveform that is modulated using the first voltage waveform and a first reference voltage waveform different in frequency from the first voltage waveform, and supplying a third voltage waveform that is the low frequency side component of the second voltage waveform. The displacement measurement device calculates the displacement between the eddy current type displacement sensor and the measurement object on the basis of the frequency of the third voltage waveform.SELECTED DRAWING: Figure 9

Description

  The present invention relates to a displacement measuring device that measures displacement between a displacement sensor and a measurement object (made of metal). In particular, in a machine tool equipped with an automatic tool changer such as a machining center (hereinafter abbreviated as “MC”), when a tool holder is automatically changed with respect to a spindle by a robot arm or the like, The present invention relates to a displacement measuring device for measuring the displacement of the outer periphery of a flange of a tool holder in order to confirm whether the holder is set at the center of rotation of a spindle.

  Eddy current displacement sensors are used in many industrial machinery for many rotating machines. Among them, the important ones are regularly monitored and constantly monitored for the state of the machine, especially vibration. And is used for abnormality analysis and diagnosis.

  Shinkawa Electric Co., Ltd., “Web Magazine, SHINKAWA Times”, “Vol.2 No.1 January 13, 2010”, “Column”, “Monitoring of rotating machine condition vol.2 Principle of eddy current displacement sensor” Page, [online], January 13, 2010, [Search May 11, 2015], Internet <URL: http://www.shinkawa.co.jp/ magazine / vol.2_column_sst.html> (Non-Patent Document 1) shows the principle of an eddy current displacement sensor as shown in FIG. An eddy current displacement sensor is basically a displacement meter that measures the displacement (gap) between a sensor and a target. The reason why vibration measurement is possible with this displacement meter is that the frequency response of the eddy current displacement sensor is as wide as about DC to 10 kHz, and there is a gap in the range of several tens to several hundreds of Hz that is the subject of normal rotating shaft vibration measurement. This is because the output of the converter with respect to the change in (sensor input) follows one-on-one. The static characteristics of the eddy current displacement meter output a voltage proportional to the displacement within the range used as shown in FIG. When the target vibrates in the range of x1 to x3 with x2 as the center, the displacement with respect to time is shown as in FIG. The output voltage of the converter appears as a waveform of the output voltage with respect to time as shown in FIG. At this time, displacements (gap) x1, x2, and x3 with respect to the output voltages y1, y2, and y3 are known values and are in a substantially proportional relationship. Therefore, the vibration amplitude can be calculated by calculating the deviation (y3−y1) between y3 and y1 using a vibration monitor or the like. Furthermore, since the output waveform of the displacement meter shows a vibration waveform, it is possible to observe the waveform and analyze the vibration.

Japanese Patent Laid-Open No. 2006-317387 (Patent Document 1) discloses an eddy current displacement sensor in which an inductance changes in accordance with a displacement with a measurement object (metal) in a machine tool as shown in FIG. Is used to determine whether the tool holder 302 is mounted abnormally in a machine tool having a rotating shaft. In that case, it is described that an equivalent circuit of the eddy current displacement sensor is assumed to be a series circuit of an inductance L, a capacitance C, and a resistance R. As shown in FIG. 3, in order to measure the displacement between the tool flange 303 and the eddy current type displacement sensor 312, the eddy current type displacement sensor 312 and alternating currents of various frequencies (f _{1 to} f _i ) are eddy current type. An oscillation circuit 321 supplied to the displacement sensor 312; a rectifier circuit 322 that rectifies an AC voltage appearing in the eddy current displacement sensor 312, a filter circuit 323 that extracts a DC component of the rectified voltage waveform; and An analog / digital converter 324 (hereinafter referred to as “ADC”) for converting the signal into a signal, and a functional module 330 including a microcomputer 326 and a memory 325 for calculating the inductance L based on the digital signal. Yes. As shown in FIG. 4, the microcomputer 326 includes a frequency converter 400 that indicates an oscillation frequency, an inductance calculator 410 that calculates an inductance based on a signal from the detection circuit 320, and a calculated inductance. , A displacement calculation unit 420 that calculates the displacement, and an abnormality determination unit 430 that determines an abnormality based on the calculated displacement. A digital signal indicating the amplitude (V _{1 to} V _i ) of the AC voltage appearing at the eddy current displacement sensor 312 is supplied from the detection circuit 320 to the function module 330 to the inductance calculation unit 410. Based on the inductance L calculated by solving n simultaneous equations as shown in Equation 1 with i = 1 to n, the displacement (gap) between the tool flange 303 and the eddy current displacement sensor 312 is measured, and the tool It is described that the abnormality of the mounting state of the holder on the spindle is determined.
(Equation 1)
V _i = | jω _i L + 1 / (jω _i C) + R | × E _i (i = 1 to n)
Further, the step of changing the frequency of the AC signal applied to the eddy current displacement sensor 312 is made finer, and the amplitude V of the signal appearing in the eddy current displacement sensor 312 is detected while sweeping the frequency of the AC signal almost steplessly. To do. When the sweep is completed in all of the sweep range (f _{s to} f _e ), the inductance calculation 410 calculates the change in the signal level V appearing in the eddy current displacement sensor 312 with respect to the change in the frequency of the AC signal, that is, the differential value dV. / Dω (ω = 2πf) is calculated. Subsequently, by substituting the differential value dV / dω into the calculation formula derived by differentiating the mathematical expression for obtaining the signal appearing in the eddy current displacement sensor 312 as in the above formula 1 with respect to the angular frequency ω, The inductance component L of the current type displacement sensor 312 can be calculated. Finally, it is described that the displacement calculation unit 420 determines the displacement (gap) from the outer peripheral surface of the tool flange 303 from the eddy current displacement sensor 312 corresponding to the inductance component L.

  Japanese Patent Application Laid-Open No. 2004-276145 (Patent Document 2) discloses an eddy current that detects, as an electrical signal, a displacement up to the outer peripheral surface of a flange portion of a tool holder mounted on a spindle in a chuck error device incorporated in a machine tool. And a data processing device that stores the displacement measured by the eddy current displacement sensor in a memory and calculates the amount of eccentricity of the tool holder based on the displacement. Then, the CPU in the data processing apparatus performs FFT (Fast Fourier Transform) analysis on the displacement of each rotation of the tool holder, decomposes it into each frequency component, and doubles the amplitude value of the fundamental frequency component. If the difference between the eccentric amount T1 of the first rotation and the eccentric amount T2 of the second rotation is equal to or greater than a predetermined threshold value, it is determined as a chuck error (abnormal mounting state). It is described that when it is less than a predetermined value, it is determined to be normal.

  Japanese Patent Laid-Open No. 2005-333426 (Patent Document 3) discloses a self-oscillation type displacement detection sensor 570 whose oscillation frequency is determined based on the product of an inductance and a capacitance of a capacitor. Displacement detection system (displacement detection device) that detects changes in displacement (gap) from the object based on changes in oscillation intensity or oscillation frequency caused by eddy current generated in the object by applying the output magnetic flux to the object ) Is described. FIG. 5 is an explanatory diagram schematically showing a configuration example of a displacement detection system (displacement detection device). This displacement detection apparatus includes a storage unit 510 in the control circuit 500 connected to the variable oscillator 520 and the detection unit 580, and stores the resonance frequency detected for the resonance circuit 570 in the storage unit 510. The control circuit 500 detects the displacement of the displacement detection target T by using the stored resonance frequency as the driving frequency. A technique is described in which a drive frequency is estimated to match the resonance frequency after the change by this detection method, and a decrease in oscillation intensity due to a change in the resonance frequency is suppressed.

JP 2006-317387 A JP 2004-276145 A JP 2005-333426 A

Shinkawa Electric Co., Ltd., “Web Magazine, SHINKAWA Times”, “Vol.2 No.1 January 13, 2010”, “Column”, “Monitoring of rotating machine condition vol.2 Principle of eddy current displacement sensor” Page, [online], January 13, 2010, [Search May 11, 2015], Internet <URL: http://www.shinkawa.co.jp/magazine/vol.2_column_sst. html>

  Non-Patent Document 1 discloses the principle of a general eddy current displacement sensor, but does not disclose the relationship between the resonance frequency and the displacement between the sensor and the target, and the measurement method and configuration of the resonance frequency.

  Patent Document 1 describes a machine tool that uses a eddy current displacement sensor whose inductance changes according to the displacement between the object to be measured and determines a tool holder mounting state abnormality in a machine tool having a rotating shaft. However, when obtaining the inductance of the eddy current type displacement sensor, there is a problem that a process for solving simultaneous equations based on a circuit equation is complicated and a microcomputer for the process is required.

  In Patent Document 2, in a chuck error device incorporated in a machine tool, a displacement d to an outer peripheral surface of a flange portion of a tool holder attached to a spindle is measured by an eddy current displacement sensor, and based on the displacement, Although it is described that a data processing device for calculating the amount of eccentricity of the tool holder is described, what kind of response of the eddy current type displacement sensor is noted, and what kind of response is associated with the calculation of displacement There is not enough disclosure.

Patent Document 3 discloses a displacement detection device that detects changes in displacement (gap) from an object based on changes in oscillation intensity and oscillation frequency caused by eddy currents generated in the object in a self-oscillation type displacement detection sensor. As shown in FIG. 6, it is described that when the gap between the inductor (coil) functioning as the displacement detection unit and the target object is reduced, the resonance frequency is increased and the resonance voltage is decreased. However, there is no disclosure about increasing the measurement accuracy or sensitivity of the oscillation frequency.

  The present invention has been made based on the above circumstances, and an object of the present invention is good even if it is simple and small-scale when measuring the displacement between the eddy current displacement sensor and the measurement object. By providing a displacement measuring device having accuracy and sensitivity, particularly by improving the measurement accuracy or sensitivity of the oscillation frequency of the voltage waveform supplied by the eddy current displacement sensor, the eddy current displacement sensor and the object to be measured An object of the present invention is to provide a displacement measuring device that improves the measurement accuracy or measurement sensitivity for displacement with respect to (for example, a tool flange).

  An object of the present invention is to provide an eddy current displacement sensor that supplies a first voltage waveform whose oscillation frequency changes according to the voltage value of the control voltage and the displacement of the object to be measured, the first voltage waveform, A frequency conversion that generates a second voltage waveform modulated using a first reference voltage waveform having a frequency different from that of the first voltage waveform, and supplies a third voltage waveform that is a low frequency component of the second voltage waveform. And calculating a displacement between the eddy current displacement sensor and the object to be measured based on the frequency of the third voltage waveform.

The object of the present invention is to provide the frequency conversion unit including a first conversion circuit including a first modulator and a first bandpass filter, and the first modulator is generated based on a first clock waveform having a predetermined frequency. Generating a second voltage waveform that is a voltage waveform including a frequency component corresponding to a frequency difference between the first reference voltage waveform and the first voltage waveform, and the first band-pass filter generates the second voltage waveform. By providing the third voltage waveform based on
Alternatively, the frequency conversion unit includes a second conversion circuit including a second modulator and a second bandpass filter, and the second modulator is based on a second clock waveform having a frequency lower than the frequency of the first clock waveform. A fourth voltage waveform that is a voltage waveform including a frequency component corresponding to a frequency difference between the second reference voltage waveform generated at a frequency lower than the frequency of the first reference voltage waveform and the third voltage waveform. The second bandpass filter generates a fifth voltage waveform based on the fourth voltage waveform,
Alternatively, the frequency conversion unit includes a third conversion circuit including a third modulator and a third bandpass filter, and the third modulator is based on a third clock waveform having a frequency lower than the frequency of the second clock waveform. A sixth voltage waveform that is a voltage waveform including a frequency component corresponding to a frequency difference between the third reference voltage waveform generated at a frequency lower than the frequency of the second reference voltage waveform and the fifth voltage waveform. The third bandpass filter generates a seventh voltage waveform based on the sixth voltage waveform,
Alternatively, the frequency conversion circuit generates the first reference voltage waveform based on the first clock waveform, and the second reference voltage waveform based on the second clock waveform. By including a second low-pass filter and a third low-pass filter that generates the third reference voltage waveform based on the third clock waveform,
Alternatively, the period of the voltage waveform converted to a frequency according to the frequency of the first voltage waveform by the frequency converter by counting with a second reference clock waveform of a predetermined frequency generated by the counting unit reference clock oscillator By providing a cycle time counting unit that counts the count number corresponding to, and a displacement calculation unit that calculates the displacement corresponding to the count number,
Alternatively, a machine tool that includes a displacement measuring device, a main spindle that is rotationally driven, and a tool holder to which a cutting tool is attached, and that drives the main spindle to which the tool holder is mounted to process a workpiece, the displacement being the machine tool. By measuring the displacement to the flange outer peripheral surface of the tool holder mounted on the spindle by a measuring device, and determining normality or abnormality of the mounting state of the tool holder on the spindle,
Alternatively, a displacement measuring device and a processing device including a measured object to be translated, wherein the displacement measuring device measures a displacement between the displacement measuring device and the measured object, and the measured object. This is more effectively achieved by determining the state of spatial installation of objects.

  According to the displacement measuring apparatus using the eddy current displacement sensor of the present invention, the voltage waveform supplied from the eddy current displacement sensor and the voltage waveform supplied from the eddy current displacement sensor are different in frequency. By providing a frequency converter that extracts the low-frequency component of the modulated voltage waveform, the frequency change of the voltage waveform that responds to the displacement between the eddy current displacement sensor and the object to be measured The ratio can be increased to improve the measurement accuracy or sensitivity for the displacement.

It is a schematic block diagram of the conventional high frequency oscillation type proximity sensor. (A) shows the relationship between the displacement of a sensor and a target, and an output waveform in the conventional high frequency oscillation type proximity sensor. (B) shows how the displacement between the sensor and the target changes over time. (C) shows how the output voltage changes with time corresponding to the displacement between the sensor and the target. It is a schematic block diagram of the machine tool provided with the tool shake (abnormality detection) displacement measuring device using the eddy current type displacement sensor of a prior art example. The block diagram of the functional module which is provided in the inside of the microcomputer shown in FIG. 3 and determines the mounting state of the tool holder on the spindle based on the displacement calculated from the inductance of the sensor (coil) is shown. It is explanatory drawing which shows typically the structural example of the conventional displacement detection system (displacement detection apparatus). It is explanatory drawing which shows the detection method of the displacement of a displacement detection target object based on the change of the resonant frequency using the conventional displacement detection apparatus. (A) is explanatory drawing which shows the structure of the spindle head vicinity of the machine tool provided with the displacement measuring device using the eddy current type displacement sensor for detecting the eccentric amount of the tool holder in 1st Embodiment of this invention, (B) is a bottom view of (A). It is a schematic block diagram of the machine tool provided with the displacement measuring device using the eddy current type displacement sensor in 1st Embodiment of this invention. It is a block diagram to the frequency conversion part of the displacement measuring device which used the eddy current type displacement sensor in 1st Embodiment of this invention. It is a block diagram of the period time counting part using the counter in 1st Embodiment of this invention. In the first embodiment of the present invention, it is a graph of the rate of change of the fundamental output frequency f _vo with respect to the fundamental frequency f _vi from eddy current displacement sensor. In the first embodiment of the present invention, linear interpolation between A and B using point A (n _k , d _k ) and point B (n _{k + 1} , d _{k + 1} ) on the conversion table is performed, it is a method of calculating a displacement d _m corresponding to the measured count value n _m. It is a flowchart which shows the example of the process which measures the eccentric amount of a tool holder and determines the chuck | zipper error of a tool holder in 1st Embodiment of this invention. It is a flowchart which shows the example of the subroutine process which measures the displacement d of the sensor head of a sensor part, and the outer peripheral surface of a tool holder in 1st Embodiment of this invention. It is a flowchart which shows the example of the process which calculates each eccentric amount of the 1st rotation of the tool holder of the 1st Embodiment of this invention-the Nth rotation. It is a flowchart which shows the example of the process which determines the presence or absence of the chuck | zipper error in 1st Embodiment of this invention. (A) in 2nd Embodiment of this invention is a structural example of the band pass filter which connected the differentiation circuit and the integration circuit in series. (B) is a configuration example of a band pass filter in which the input side impedance of the operational amplifier A is a CR series differentiating circuit and a CR parallel integrating circuit is assigned to the feedback side impedance. It is a structural example of the low-pass filter in 2nd Embodiment of this invention. (A) is an example in which the MOD in the present invention is realized by a multiplier configured by disposing a voltage-controlled resistance element on the input side of an operational amplifier and a feedback resistor Rf in a feedback loop. (B) is a configuration example of a multiplier in which an n-type field effect transistor is disposed as a voltage-controlled resistance element. (A) is in the VCO circuit is a diagram showing the relationship between the output frequency f _out with respect to the control voltage V _cont. (B) is a configuration example of a VCO circuit using an LC resonance circuit including a varicap. It is the example which installed the sensor part in the bottom face of the headstock in this invention. It is the example applied to the displacement measurement of the to-be-measured target object translated in this invention. (A) is an example applied to the measurement of the displacement of a target that translates in the left-right direction with respect to the eddy current displacement sensor in the present invention. (B) is an example applied to the displacement measurement of a target that moves so as to approach or move away from the eddy current displacement sensor in the present invention.

  In the displacement measuring apparatus using the eddy current displacement sensor of the present invention, the voltage waveform supplied from the eddy current displacement sensor and the voltage waveform supplied from the eddy current displacement sensor are modulated using voltage waveforms having different frequencies. A frequency conversion unit that extracts a low-frequency component in the measured voltage waveform, and amplifies a frequency change ratio in the voltage waveform with respect to the displacement between the eddy current displacement sensor and the object to be measured. It is possible to provide a displacement measuring device that improves the measurement accuracy or measurement sensitivity of the. In particular, in a machine tool equipped with an automatic tool changer such as MC, it is effective for detecting eccentricity due to foreign matter adhesion between the spindle and the tool holder.

  Hereinafter, a first embodiment of a displacement measuring apparatus according to the present invention will be described with reference to the drawings.

  FIG. 7A shows a schematic configuration diagram in the vicinity of a spindle head of a machine tool to be measured by the displacement measuring apparatus according to the present invention in the first embodiment, and an eddy current displacement sensor (the whole is denoted by reference numeral 720). It is a figure which shows the attachment position. FIG. 7B is a bottom view of FIG.

  The head stock 704 of the machine tool is attached to an appropriate saddle or the like and moves relative to a table (not shown). The spindle 703 supported by the spindle stock 704 has a shank hole at the tip, and is engaged with the tool holder 701 by two claws. The tool holder 701 has an appropriate outer diameter, and is exchanged with respect to the main shaft 704 by an automatic tool changer (not shown). The tool holder 701 has a cutting tool 700, and performs necessary processing on the workpiece on the table.

  The eddy current displacement sensor 720 includes a sensor head 722 inserted into the main body 721. The main body 721 is supported by the holder arm 723 by nuts 726a and 726b, and the holder arm 723 is attached to the support structure 724. A signal detected by the sensor head 722 is sent to a frequency conversion unit 812 described later via a signal line 725.

  The tool holder 701 includes a flange portion 705 having a maximum diameter. In the automatic tool change position, the sensor head 722 of the eddy current displacement sensor 720 is disposed at a position facing the flange portion 705 of the tool holder 701. At this time, the displacement d (gap) formed by the tip of the sensor head 722 and the flange portion 705 of the tool holder may be 3 mm, for example. The flange 705 is a mounting tool such as a cutting tool having a removable structure, and a metal material having a strong magnetic reaction is used as the material.

  When the main shaft 703 is rotated in this state, the flange portion 705 of the tool holder rotates with respect to the sensor head 722. When the displacement d changes according to this rotational movement, the impedance (inductance) formed between the flange portion 705 of the tool holder and the sensor head 722 changes, and the eccentric amount of the flange portion 705 is reduced by the action described later. Can be detected. When the amount of eccentricity exceeds a predetermined value, it can be determined that a clamp abnormality has occurred due to a cause such as a biting of chips between the tool holder 701 and the main shaft 703. Further, the rotation of the main shaft 703 may be stopped and necessary processing may be performed.

FIG. 8 is a schematic configuration diagram of a displacement measuring apparatus 800 used in the present invention. Displacement measuring apparatus 800 according to the present invention includes a control voltage data transmission unit 810 supplies the digital data of the control voltage V _cont to the eddy current displacement sensor 720 oscillates based on the control voltage V _cont, metal measurement object (in this case, the flange portion 705) eddy current generation due to the impedance (inductance) for supplying a resonance frequency corresponding to the change of the voltage waveform having a basic frequency f _vi to the frequency conversion unit 812 eddy current displacement sensor 720 of And a frequency converter 812 that supplies the voltage waveform having the basic output frequency f _vo subjected to the filtering process and the low-frequency conversion process to the voltage waveform having the basic frequency f _vi to the cycle time counting unit 813, and measured. A displacement calculating unit 814 that calculates a displacement d between the flange 705 and the eddy current displacement sensor 720 based on the basic output frequency f _vo. .

Furthermore, a block diagram of the control voltage data transmission unit 810, the eddy current displacement sensor 720, and the frequency conversion unit 812 is shown in FIG. The control voltage data transmission unit 810 converts the parallel data of digital control numerical values corresponding to the control voltage V _cont into digital data according to a command from the computer 815, and converts the parallel data into serial data. This is supplied to the interface 913 of the displacement sensor 720. The DAC 914 holds the control numerical value and outputs a control voltage V _cont that is D / A converted based on the numerical value. The control voltage V _cont is supplied to a voltage / frequency conversion circuit 915 (hereinafter referred to as “VCO circuit”). Note that the VCO circuit includes a sensor coil for detecting a change in impedance due to eddy current generation, as will be described later.

Since an eddy current corresponding to the displacement d between the sensor head 722 and the flange portion 705 that is a metal object to be measured is generated and the impedance (inductance) of the eddy current displacement sensor 720 is changed, the VCO circuit The resonance frequency of 915 changes. This resonance frequency is referred to as the fundamental frequency f _vi in the present invention, and the range of change is, for example, 11415.2 to 11416.3 [kHz], and about 0.01% in the change ratio based on 11415.2 [kHz]. Therefore, it is difficult to ensure sufficient measurement sensitivity or accuracy.

Therefore, in the present invention, by providing the frequency conversion unit 812 that converts the fundamental frequency f _vi to the low frequency side, the frequency after conversion, that is, the fundamental output frequency f _vo , with respect to the change ratio of the fundamental frequency f _vi. To increase the rate of change.

A block diagram showing an outline of the frequency conversion unit 812 is shown in FIG. As shown in FIG. 9, a voltage waveform v _i having this basic frequency f _vi is inputted, and a band pass filter ₀ 917, a buffer 918, a modulator ₁ 919, a band pass filter ₁ 920, a buffer 921, a modulator ₂ 922, a band pass are obtained. A voltage waveform v _zc is output through a filter ₂ 923, a buffer 924, a modulator ₃ 925, a bandpass filter ₃ 926, a buffer 927, and a zero cross circuit (ZERO CROSS) 928. In this embodiment, a block composed of a buffer (hereinafter referred to as “BF”), a modulator (hereinafter referred to as “MOD”), and a bandpass filter (hereinafter referred to as “BPF”) is converted into one conversion circuit. The frequency conversion is performed by three conversion circuits. As a process before inputting the voltage waveform v _i having the fundamental frequency f _vi to the first conversion circuit, noise is removed through the BPF. And BF performs impedance conversion of the voltage waveform which passed BPF. When the reference signal A ₀ sin (ω ₁ ) t that has passed through the LPF ₁ and the voltage waveform A ₁ sin (ω ₂ ) t that has passed through the first BF are input to the first MOD 1, A composite waveform having a (ω ₁ + ω ₂ ) t component and a sin (ω ₁ −ω ₂ ) t component is generated. For example, a multiplication circuit may be used as such a conversion processing circuit. Then, when the combined waveform passes through the BPF 1 at the next stage of the conversion processing circuit, a filtering process is performed so that the high frequency component is blocked and only the low frequency component v _o1 passes. Sequentially in this manner, the voltage waveform of the fundamental frequency f _vi in the first stage is converted into a voltage waveform of the first low-frequency converting the frequency f _vo1, the first voltage waveform of a low frequency converted frequency f _vo1 second stage The voltage waveform of the second low frequency conversion frequency f _vo2 is converted into a voltage waveform of the second low frequency conversion frequency f _{vo2, and} the voltage waveform of the second low frequency conversion frequency f _vo2 is converted into a voltage waveform of the third low frequency conversion frequency f _vo3 in the third stage. Note that the frequency f _vo3 of the voltage waveform v _o is the same as the basic output frequency f _vo in the present invention. In the embodiment, the conversion circuit composed of BF, MOD, and BPF is used. However, LPF may be used instead of BPF depending on the characteristics and performance of the conversion circuit. In addition, the conversion circuit composed of BF, MOD, and BPF is connected in three stages. However, for example, it may be one stage, two stages, or four or more stages may be connected to form a frequency conversion unit. The number of stages is not limited.

  In each MOD, a voltage waveform having a fixed frequency used for frequency modulation (for example, f1: 12 MHz, f2: 750 kHz, and f3: 187.5 kHz in FIG. 9 corresponds) is generated by the clock generator 934. The basic sine wave component is extracted by passing through each low-pass filter (corresponding to LPF1, LPF2, and LPF3 in FIG. 9), and supplied to each corresponding MOD. Is done.

In the first embodiment of the present invention, the MODs 919, 922, and 925 of the frequency converter 812 are converted into the voltage waveform frequency and the basic output frequency f _vo based on the fundamental frequency f _vi , but the eddy current type is used. Table 1 shows the correspondence between the frequency of the voltage waveform sequentially converted by the frequency converter and the basic output frequency f _vo based on the basic frequency f _vi from the displacement sensor. The change rate of the basic frequency f _vi is 0.001%, 0.005%, and 0.01% with respect to 11415.2 [kHz], whereas the change rate of the basic output frequency f _vo With respect to 22.3 [kHz], 0.515%, 2.627%, and 5.395% correspond. When the corresponding change ratios are compared, 515 times (0.515%: 0.001%), 525 times (2.627%: 0.005%), 539 times (5.395%: 0.00), respectively. The change ratio is remarkably increased to 01%). Further, the change ratio of the basic output frequency f _vo with respect to the change ratio of the basic frequency f _vi is substantially proportional to the illustration (see FIG. 11).

Thus, in the frequency conversion section 812, with respect to the change of the fundamental frequency f _vi, such that the change in the change ratio of the fundamental output frequency f _vo is increased significantly, the measurement sensitivity is increased, a fundamental frequency f _vi Can be converted to the low frequency side. As a result, the sensitivity for detecting the displacement d between the sensor head 722 and the flange portion 705, which is a metal object to be measured, can be improved with the improvement of the detection sensitivity of the basic output frequency _fvo .

As shown in FIG. 8, a cycle time counting unit 813 is arranged between the computer 815 or the displacement calculating unit 814 and the frequency converting unit 812. As shown in FIG. 10, the cycle time counting unit 813 is supplied with a rectangular wave signal v _zc having a clock pulse φ of 150 MHz and a basic output frequency f _vo output from the frequency conversion unit 812. Then, the cycle time counting unit 813 supplies the displacement calculation unit 814 with a count number obtained by counting the clock pulse φ with the counter 944 in a period corresponding to one cycle of the signal v _zc .

In the first embodiment of the present invention, the cycle time counting unit 813 counts the period of the voltage waveform having the basic output frequency f _vo converted by the frequency converting unit 812 based on the basic frequency f _vi . Table 2 shows a correspondence table of the period, the number of counters, and the basic output frequency f _vo based on the basic frequency f _vi from the eddy current displacement sensor. Here, when the change in the basic frequency f _vi with respect to 11415.2 [kHz] is compared with the increment of the count corresponding to the period of the voltage waveform having the basic output frequency f _vo , 0.01%, 363 counts, 2314 counts and 7054 counts correspond to 0.05% and 0.1%, respectively, and all change greatly, that is, the sensitivity is expanded.

The count number is inversely proportional to the basic output frequency f _vo, and the displacement d can be calculated by detecting the count number. In the first embodiment of the present invention, when the calculation is performed, a conversion table that stores the correspondence between the count number and the displacement d is provided, and the final measurement amount is obtained by performing conversion according to the conversion table. A displacement d is obtained. Table 3 shows a conversion table indicating the correspondence between the counter number n and the displacement d based on the basic output frequency _fvo .

Regarding the use of the conversion table, the measured count value does not normally coincide with the count value prepared in advance in the conversion table. Therefore, as shown in FIG. Two count values n _k and n _{k + 1} stored in advance in the conversion table are selected, and two count numbers n and displacement d, respectively, for the interval [n _k , n _{k + 1} ] In other words, linear displacement between A and B using the point A (n _k , d _k ) and the point B (n _{k + 1} , d _{k + 1} ) is performed, and the displacement d corresponding to the measured count number n _{m. Although m} can be calculated, an interpolation method other than linear interpolation may be used.

  Next, processing for determining a chuck error of the tool holder 701 by measuring the eccentric amount T of the tool holder 701 will be described with reference to the flowchart of FIG.

First, an automatic tool change (AUTOMATIC TOOL CHANGE) is started (S100). Then, the number of rotations of the tool holder 701 and how many times the measurement for one rotation of the tool holder is performed, that is, the number of times of measurement N is set (S200). The computer 815 instructs to rotate the tool holder 701 at the set number of rotations (S300). During the process of measuring the amount of eccentricity, a variable k that stores the number k of rotations of the tool holder 701 is initialized to 1 (S400). Next, the subroutine jumps to a subroutine for measuring the displacement d between the sensor head 722 of the eddy current type displacement sensor 720 and the outer peripheral surface of the tool holder 701, that is, the flange portion, and the displacement d for one rotation (L displacement d described later). Is measured, and the process returns to step 600 (S500), and the variable k is counted up (S600). In order to determine the end of measurement, if it is determined whether or not the variable k exceeds the set number of measurements N, the process returns to step 500, and if it is determined whether or not the variable k exceeds the set number of measurements N, The process proceeds to step 800 (S700). The process jumps to a subroutine for calculating the respective eccentric amounts T _k corresponding to the first to N-th rotations of the tool holder 701, returns after calculation, and proceeds to step 900 (S800). In order to determine the chuck error of the tool holder 701 based on the maximum value, the average value, and the minimum value of the eccentric amount T _k for the first to N-th rotations, the process jumps to a subroutine (S800 to S810 described later). After the determination, the process returns and proceeds to step 1000 (S900). The determination result is displayed on the display unit of the computer 815 (S1000).

Here, the subroutine process of step 500, that is, the process of measuring the displacement d of one rotation between the sensor head 722 of the sensor unit and the outer peripheral surface of the tool holder, that is, the flange part 705 will be described with reference to the flowchart of FIG. A variable L is used to manage the number of data of the displacement d in one rotation (one turn) of the tool holder, and the variable L is initialized to 0 before measurement (S501). Then, in order to start measurement after detecting the reference of the rotation angle (azimuth angle) of the tool holder 701, in the case of the first rotation of measurement (S502), until the reference of the rotation angle of the tool holder 701 is detected. The displacement d is not read from the displacement calculation unit 814 and the process waits in the loop of step 503 (S503). In addition, about the said reference | standard, a recessed part or a convex part is given to the flange part 705, and it may detect from the increase / decrease in the displacement d in a recessed part or a convex part, or an optical sensor may be provided and the said reference | standard may be detected, The detection method is not limited. Further, regarding the detection of the reference, for example, the detection may be continued until the rotation speed becomes constant, and the detection may be omitted when it is determined to be constant. In the detection order, the flowchart is modified to detect after the displacement d corresponding to the rotation angle is read from the displacement calculation unit 814 (S504), and the timing of the break (start or end) for one rotation of the tool holder 701 is detected. You may make it do. Next, the reference of the rotation angle of the tool holder 701 is detected (S503), and the displacement d corresponding to the rotation angle is sequentially read from the displacement calculation unit 814 (S504). The displacement d is stored in the array variable D (k, L) as the displacement d measured for the variable Lth during the rotation of the k-th rotation (S505). Waiting for a predetermined time until the rotation angle changes to the next rotation angle, the variable L is counted up (S506). If the reference for the rotation angle of the tool holder has not yet been detected, the process returns to step 504 (S507). When the reference of the rotation angle of the tool holder 701 is detected again, the measurement of the displacement d data for one rotation of the tool holder is finished (S507), and the process proceeds to step 508, and the array corresponding to the number of displacement data of the k-th rotation The variable L (k) = L-1 is stored, the subroutine process is terminated, and the process returns (S508). The process waits for a predetermined time, but the predetermined time is changed so that the number of data of the displacement d per rotation is adjusted to be approximately the same and can be easily normalized by changing the predetermined time according to the rotation speed. It is also possible to add a configuration to control, shorten the predetermined time for a certain period from the start of the displacement measurement, extend the predetermined time after the lapse of the certain period, and reduce the difference in the number of data of the displacement d per rotation. A configuration that can be controlled to be provided may be added, and a corresponding modification may be added to arrange steps for controlling the configuration in the flowchart.

  The subroutine process of step 800, that is, the process of calculating the eccentric amounts T of the first rotation to the Nth rotation of the tool holder 701 will be described with reference to the flowchart of FIG. About the outline of this processing, since the measurement data of the displacement d output from the sensor unit is stored in the array variable D (k, L) corresponding to the rotation angle θ of the tool holder 701, 1 of the tool holder 701 is stored. Since (maximum value−minimum value) in the displacement d for the rotation, that is, the amplitude value can be regarded as twice the eccentric amount T of the tool holder 701, the computer 815 performs each k-th rotation from the first rotation to the N-th rotation. Are obtained, and an eccentric amount T (k) of each k-th rotation of the tool holder 701 from the first rotation to the N-th rotation is acquired.

  As this processing procedure, for the k-th rotation, the array variable D (k, L) and the adjacent array variable D (k, L + 1) are sequentially compared to extract the maximum value and the minimum value, and the array variable D (k , L) is calculated, and finally divided by the array variable L (k), which is the number of displacement data of the k-th rotation, to obtain an average value.

  The variable L is initialized (L = 0), and the variable Max = variable Min = array variable D (k, L) is set (S801). If the relationship of array variable (k, L) <array variable (k, L + 1) is satisfied, the process proceeds to step 803 (S802), variable Max = array variable (k, L + 1) is set, and the process proceeds to step 804 (S803). If the relationship of array variable (k, L) <array variable (k, L + 1) is not satisfied, the process proceeds to step 804 (S802).

  If the relationship of array variable (k, L) <array variable (k, L + 1) is satisfied, step 805 (S804), variable Min = array variable (k, L + 1) are set, and the process proceeds to step 806 (S805). If the relationship of array variable (k, L) <array variable (k, L + 1) is not satisfied, the process proceeds to step 806 (S804).

  If L> array variable L (k) is not satisfied (S807), the process returns to step 802. When L> array variable L (k) (S807), that is, when comparison between data of all displacements d at the k-th rotation is completed, array variable Min (k) = Min, array variable Max (k) = As the variable Max, an array variable T (k) = (variable Max−variable Min) / 2 corresponding to the eccentric amount of the k-th rotation is calculated and stored (S808). In order to store the amount of eccentricity of the next (k + 1) th rotation, the variable k is counted up (S809). When k> N is not satisfied, that is, when measurement is continued without the variable k exceeding the number of times of measurement N (S810), the process returns to step 802. When k> N, that is, when the measurement is finished, the subroutine processing from S901 to S912 is finished and the process returns to step 900.

Subroutine processing in the next step 900, that is, processing for determining the presence or absence of a chuck error will be described with reference to the flowchart of FIG. Regarding the determination method in this process, as an example, if there is an average value for each eccentric amount of the first rotation to the N-th rotation of the tool holder that is equal to or greater than a threshold value, it is determined as a chuck error. Similarly, if the difference between the maximum value (variable T _max ) and the minimum value (variable T _min ) in each of the first to N-th rotations of the tool holder is equal to or greater than a threshold value, a chuck error similarly However, it is not limited to this determination method. For example, each eccentric amount may be compared with a predetermined threshold value, and the chuck error may be determined based on the number of eccentric amounts exceeding the threshold value. Further, statistical processing is performed for each eccentric amount. A method may be employed in which a chuck error is determined based on the statistical data obtained by performing the above.

As an initial step in the subroutine 900, an initial value of k = 1 is performed as variable initialization and initial value setting, and variable T _max = variable T _min = array variable T (1) (the eccentric amount of the first rotation Corresponding variable) is set (S901). The eccentric amounts are sequentially compared, and if T (k) <T (k + 1) is not satisfied (S902), the process proceeds to step 904. If T (k) <T (k + 1) is satisfied (S902), the variable _Tmax is updated to array variable T (k + 1), and the process proceeds to step 904 (S903). Next, when the relationship T (k)> T (k + 1) is not satisfied, the process proceeds to step 906 (S904). T (k)> When a relationship T (k + 1) (S904 ), and updates the T _min = array variable T (k + 1), the process proceeds to step 906 (S905). In order to calculate the average value of the eccentricity, the variable _Tsum = variable _Tsum + array variable T (k + 1) is calculated, and the array variable T (k) is sequentially added (S906). Is finished, the variable k is counted up in order to proceed with the comparison of the adjacent eccentric amounts and the total eccentric amount processing (S7).

Next, when the variable k does not exceed the set number of times of measurement N, that is, when the processing for calculating the maximum value, the minimum value, and the total amount of eccentricity does not end, the process returns to step 902 and the processing is continued using the counted up k. . When k> N, that is, when this process is terminated, the average value T _ave (= Sum / N) of the eccentricity is calculated as a summation (S909). Finally, in order to determine the chuck error, T _ave and (T _max −T _min ) are compared with the corresponding threshold values. Specifically, if T _ave <the first threshold value is not satisfied (S910), or T _max −T _min <the second threshold value is not satisfied (S911), it is determined that a chuck error has occurred, the subroutine process is terminated, and the process returns. (S913). On the other hand, if T _ave <the first threshold value relationship (S910) and T _max −T _min <the second threshold value relationship (S911), it is determined that there is no chuck error, and subroutine processing is performed. And the process returns to step 900 (S912). In the subroutine 900, the first threshold value and the second threshold value are set as fixed values, but may be variable. For example, the type, material, age, etc. of the cutting tool 700 may be variable based on the attributes of the individual, or may be set and optimized based on the dimensions or material of the workpiece, and is limited. It is not something. Moreover, it is not limited to the example of the determination method shown in the embodiment, and other determination methods may be adopted.

  Next, a second embodiment of the displacement measuring apparatus according to the present invention will be described based on the drawings. In the second embodiment, a configuration example using an operational amplifier is shown for the BPF, BF, MOD, and LPF in the frequency converter 812, and circuit constants of a resistor R and a capacitor C corresponding to the cutoff frequency of the BPF and each LPF are shown. An example of An example in which the VCO circuit 915 of the eddy current displacement sensor 720 is configured using a variable capacitance diode (varicap) is shown.

First, a configuration example of a BPF is shown in FIG. 17, in which a differentiation circuit and an integration circuit are connected in series in FIG. 17A. In FIG. 17B, the input side impedance of the operational amplifier A in one stage is CR-series. The differential circuit and the feedback-side impedance are assigned with a CR parallel integrating circuit. The cutoff frequencies f _c1 and f _c2 have a relationship of f _c1 <f _c2 , and are calculated by f _c1 = (2πR ₁ C ₁ ) ⁻¹ and f _c2 = (2πR ₂ C ₂ ) ⁻¹ . That is, the BPF 1 passes a voltage waveform in a frequency band that is greater than or equal to f _{c1 and} less than or equal to f _c2 . Similarly, as shown in FIG. 18, the configuration example of the low-pass filter is configured by providing an integration circuit in the feedback loop of the operational amplifier A, and the cutoff frequency is determined by f _c = (2πRC) ⁻¹ . Table 4 shows examples of the resistance R and the capacitance C corresponding to the cut-off frequencies for BPF0 to BPF3 and LPF1 to LPF3 shown in FIG. 9 in the second embodiment of the present invention.

Next, in MODs 919, 922, and 925, a multiplier using the operational amplifier A can be used as described above. For example, a configuration example of the multiplier 960 includes an operational amplifier A as shown in FIG. On the input side, a voltage control resistor element is disposed, and a feedback resistor Rf is disposed in a feedback loop. As shown in FIG. 19 (B), as a resistive element R _v of the voltage controlled, for example, it may be arranged n-type field effect transistor or MOS transistor. In the multiplier 961, the voltage waveform v ₁ input to the drain side of the n-type field effect transistor Q is subjected to amplitude modulation by the voltage level of the voltage waveform v ₂ input to the gate side, and V _{0 to} V A multiplication result such as ₁ * V ₂ is output.

  Next, the VCO circuit 915 in the eddy current displacement sensor 720 can be configured using a variable capacitance diode (varicap). The varicap (variable capacitance diode) controls the magnitude of the reverse bias voltage applied to the diode to change the reverse bias depletion capacitance of the PN junction, thereby changing the capacitance VC across the varicap. It is an element that can. The relationship of the capacity VC with respect to the reverse bias voltage has such characteristics that the capacity VC increases when the reverse bias voltage applied to both ends of the varicap is small, and the capacity VC decreases when the reverse bias voltage is large.

In the voltage / frequency conversion circuit 915, when the voltage applied to the variable capacitance diode (varicap) (equal to the control voltage V _cont ) changes, the capacitance of the diode changes. Changes. The normal voltage / frequency conversion circuit has a characteristic that the oscillation frequency increases as the voltage increases.

The VCO circuit 915 of the eddy current type displacement sensor 720 has a sensor coil L _VCO , and a high-frequency magnetic field generated by the AC magnetic field lines generated by the sensor coil L _VCO is applied to a target (flange portion as an object to be measured) made of metal. to generate eddy currents, Inpi possessed sensor coil L _VCO - Dance properties (especially, inductance characteristics) alter.

Characteristics C ₂ -C ₅ inside the sensor characteristics L and the variable capacitance diode (varicap) having a coil L _VCO VC and the capacitor of the VCO circuit 915 form an LC resonant circuit, the LC resonant circuit, the control voltage An AC signal having a resonance frequency based on V _cont and the impedance of the sensor coil L _VCO is supplied.

As shown in FIG. 20A, the VCO circuit 915 is a circuit that controls the oscillation output frequency f _out with the control voltage V _cont . A VCO circuit having a monotonous characteristic of the oscillation output frequency f _{out with} respect to the control voltage V _cont , that is, an input / output characteristic close to a straight line is desirable. As an example of the circuit configuration of the VCO circuit 915, a VCO circuit 970 including a variable capacitance diode (varicap) as shown in FIG. The VCO circuit 970 uses the LC resonance circuit as described above, and the inductance L corresponds to the sensor coil in the present invention. The capacitance C of the resonance circuit includes the capacitance C _{VR of the} variable capacitance diode (varicap). Since the capacitance C _VR can be changed based on the control voltage V _cont as described above, the fundamental frequency f _vi is determined based on the control voltage V _cont and the inductance of the sensor coil L _VCO . The circuit configuration of the VCO circuit (voltage controlled oscillator) is not limited as long as the sensor coil can be incorporated by controlling the oscillation frequency by the input control voltage V _cont and it is necessary to have a varicap. There is no. Furthermore, since a quieter control voltage without noise is required for a higher performance VCO circuit, it is preferable to control the oscillation output frequency f _out with a digital control voltage V _cont . Also, the VCO circuit 970 shown in FIG. 20B does not specify the oscillation frequency.

  The position of the eddy current type displacement sensor unit 720 may be installed on the bottom surface of the headstock 704 as shown in FIG. 21, or may be installed on a side surface (not shown), and the installation position is not particularly limited.

  Moreover, the displacement measuring apparatus of the present invention can be applied to the displacement measurement of a measurement object to be translated as shown in the schematic diagram of FIG. In a device 980 in which the level of the stage shown in FIG. 22 affects the processing quality, such as a printing machine, a coating device for applying a chemical to a substrate, a device for polishing or rubbing the surface of the substrate, eddy current displacement If the sensor 981 and the metal xy stage 982 are provided, the distance d between the eddy current displacement sensor 981 and the xy stage 982 is moved in parallel on the xy plane. However, by using the eddy current displacement sensor 981 to measure, the distribution of the above-mentioned distance d in the xy plane is evaluated, and it is also used for adjusting the level of the xy stage 982. can do.

Further, the displacement measuring apparatus of the present invention is used to measure the displacement of the target 991 that translates in the left-right direction with respect to the eddy current displacement sensor 993 as shown in the schematic diagram of FIG. As shown in the schematic diagram of FIG. 23B, the eddy current displacement sensor 994 is also used to measure the displacement of the target 992 that moves toward and away from the front-rear direction. Can do.

100 target (metal)
101 Sensor (Coil)
DESCRIPTION OF SYMBOLS 102 Oscillation circuit 103 Resonance circuit 104 Detection circuit 105 Amplification circuit 106 Linearizer circuit 200 Target 201 Sensor 301 Tool 302 Tool holder 303 Tool flange 304 Fit part 306 Head 310 Spindle 311 Bracket 312 Eddy current displacement sensor 320 Detection circuit 321 Oscillation circuit 322 Rectifier circuit 323 Filter circuit 324 ADC
325 Memory 326 Microcomputer 327 NC of machine tool
330 Function Module 400 Frequency Conversion Unit 410 Inductance Calculation Unit 420 Displacement Calculation Unit 430 Abnormality Determination Unit 500 Control Circuit 510 Storage Unit 520 Variable Oscillation Circuit 530 Drive Circuit 540 Resistor 550 Capacitor 560 Resonance Circuit 580 Detection Unit 700 Cutting Tool 701 Tool Holder 702 Double claw 703 Main shaft 704 Main shaft base 705 Flange 720 Eddy current displacement sensor 721 Main body 722 Sensor head 723 Holder arm 724 Support 725 Signal line 726a, 726b Nut 800 Displacement measuring device 810 Control voltage data transmission unit 812 Frequency conversion unit 813 Cycle time measuring unit 814 Displacement calculating unit 815 Computer 816 Memory 817 Machine tool NC
911 Digital circuit (converts parallel data to serial data)
912 Interface 913 Interface 914 D / A converter (with data holding function)
915 VCO circuit 916 buffer 917 band pass filter 0
918 Buffer 919 Modulator 1
920 Band pass filter 1
921 Buffer 922 Modulator 2
923 Band pass filter 2
924 Buffer 925 Modulator 3
926 Bandpass filter 3
927 Buffer 928 Zero-cross circuit (outputs pulse waveform)
930 Frequency divider 931 Low pass filter 1
932 Low pass filter 2
933 Low-pass filter 3
934 Clock generator 940 Counting unit 941 Clock generator 942 Flip-flop (1/2 divider)
943 Edge detection 944 Counter 945 Latch circuit 950 Band pass filter 951 Band pass filter 952 Low pass filter 960 Multiplier 961 Multiplier 970 VCO circuit 980 Device 981 Eddy current displacement sensor 982 xy stage
991, 992 Target 993, 994 Eddy current displacement sensor

Claims (8)

An eddy current displacement sensor that supplies a first voltage waveform whose oscillation frequency changes according to the voltage value of the control voltage and the displacement of the object to be measured;
A second voltage waveform modulated using a first reference voltage waveform having a frequency different from that of the first voltage waveform is generated, and the third voltage waveform is a low frequency side component of the second voltage waveform. A frequency converter for supplying a voltage waveform,
A displacement measuring apparatus that calculates a displacement between the eddy current displacement sensor and the object to be measured based on a frequency of the third voltage waveform. The frequency conversion unit includes a first conversion circuit including a first modulator and a first bandpass filter.
The first modulator is a voltage waveform including a frequency component corresponding to a frequency difference between a first reference voltage waveform generated based on a first clock waveform having a predetermined frequency and the first voltage waveform. Generate a voltage waveform,
The displacement measuring apparatus according to claim 1, wherein the first band pass filter supplies the third voltage waveform based on the second voltage waveform. The frequency conversion unit includes a second conversion circuit including a second modulator and a second bandpass filter,
A second reference voltage waveform generated at a frequency lower than the frequency of the first reference voltage waveform based on a second clock waveform having a frequency lower than the frequency of the first clock waveform; Generating a fourth voltage waveform that is a voltage waveform including a frequency component corresponding to a frequency difference from the three voltage waveforms;
The displacement measuring apparatus according to claim 2, wherein the second band pass filter supplies a fifth voltage waveform based on the fourth voltage waveform. The frequency conversion unit includes a third conversion circuit including a third modulator and a third bandpass filter,
The third modulator includes a third reference voltage waveform generated based on a third clock waveform having a frequency lower than the frequency of the second clock waveform, and a frequency lower than the frequency of the second reference voltage waveform; Generating a sixth voltage waveform that is a voltage waveform including a frequency component corresponding to a frequency difference from the five voltage waveform;
The displacement measuring apparatus according to claim 3, wherein the third band pass filter supplies a seventh voltage waveform based on the sixth voltage waveform.   The frequency conversion circuit generates a first reference voltage waveform based on the first clock waveform, and a second low-pass filter generates the second reference voltage waveform based on the second clock waveform. The displacement measuring apparatus according to claim 4, further comprising: a low-pass filter; and a third low-pass filter that generates the third reference voltage waveform based on the third clock waveform. By counting with the second reference clock waveform of a predetermined frequency generated by the counting unit reference clock oscillator, it corresponds to the period of the voltage waveform converted to the frequency according to the frequency of the first voltage waveform by the frequency conversion unit A cycle time counting unit for counting the number of counts to be performed,
A displacement calculator that calculates the displacement corresponding to the count;
A displacement measuring device according to any one of claims 2 to 5. A displacement measuring device according to any one of claims 1 to 6, a main shaft for rotational driving, and a tool holder to which a cutting tool is attached, and the main shaft to which the tool holder is attached is rotationally driven to work. A machine tool for machining
A machine tool for determining whether the tool holder is mounted on the spindle in a normal or abnormal state by measuring the displacement of the tool holder mounted on the spindle to a flange outer peripheral surface by the displacement measuring device. A processing apparatus comprising the displacement measuring apparatus according to any one of claims 1 to 6 and an object to be measured that translates.
A processing device for measuring a displacement between the displacement measuring device and the object to be measured by the displacement measuring device and determining a state of spatial installation of the object to be measured.