WO2023063435A1 - Procédé et système de détermination de qualité de palier de machine de travail - Google Patents

Procédé et système de détermination de qualité de palier de machine de travail Download PDF

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Publication number
WO2023063435A1
WO2023063435A1 PCT/JP2022/039805 JP2022039805W WO2023063435A1 WO 2023063435 A1 WO2023063435 A1 WO 2023063435A1 JP 2022039805 W JP2022039805 W JP 2022039805W WO 2023063435 A1 WO2023063435 A1 WO 2023063435A1
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WO
WIPO (PCT)
Prior art keywords
bearing
srf
vibration
frequency
quality
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Application number
PCT/JP2022/039805
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English (en)
Japanese (ja)
Inventor
保宏 駒井
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エヌティーエンジニアリング株式会社
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Application filed by エヌティーエンジニアリング株式会社 filed Critical エヌティーエンジニアリング株式会社
Publication of WO2023063435A1 publication Critical patent/WO2023063435A1/fr

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23Q—DETAILS, COMPONENTS, OR ACCESSORIES FOR MACHINE TOOLS, e.g. ARRANGEMENTS FOR COPYING OR CONTROLLING; MACHINE TOOLS IN GENERAL CHARACTERISED BY THE CONSTRUCTION OF PARTICULAR DETAILS OR COMPONENTS; COMBINATIONS OR ASSOCIATIONS OF METAL-WORKING MACHINES, NOT DIRECTED TO A PARTICULAR RESULT
    • B23Q17/00—Arrangements for observing, indicating or measuring on machine tools
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23Q—DETAILS, COMPONENTS, OR ACCESSORIES FOR MACHINE TOOLS, e.g. ARRANGEMENTS FOR COPYING OR CONTROLLING; MACHINE TOOLS IN GENERAL CHARACTERISED BY THE CONSTRUCTION OF PARTICULAR DETAILS OR COMPONENTS; COMBINATIONS OR ASSOCIATIONS OF METAL-WORKING MACHINES, NOT DIRECTED TO A PARTICULAR RESULT
    • B23Q17/00—Arrangements for observing, indicating or measuring on machine tools
    • B23Q17/12—Arrangements for observing, indicating or measuring on machine tools for indicating or measuring vibration
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
    • G01H17/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves, not provided for in the preceding groups
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M13/00—Testing of machine parts
    • G01M13/04—Bearings
    • G01M13/045—Acoustic or vibration analysis
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M99/00—Subject matter not provided for in other groups of this subclass

Definitions

  • the present invention relates to a bearing quality determination method and system for a machine tool for determining the quality of bearings that rotatably support a spindle.
  • a boring tool is attached to the main shaft (spindle) of a machine tool, and by rotating the boring tool at high speed and feeding it out sequentially along a prepared hole, the machining diameter of the cutting edge is precisely positioned at a predetermined position. It processes the hole.
  • an abnormal frequency is calculated in advance for each part of the bearing, specifically, for each inner ring, outer ring, rolling element, and cage, and the calculated abnormal frequency corresponds to Techniques are disclosed for extracting spectral data levels and comparing them to thresholds.
  • the abnormal frequency calculated in advance using a predetermined relational expression for each part of the bearing and the level of the frequency spectrum of the digital signal obtained by detecting the vibration generated from the bearing are compared and collated. are doing. For this reason, the process of comparison and collation becomes complicated, and an expensive FFT analyzer is required for vibration measurement, which is not economical. Moreover, unless there is obvious damage to the bearing, there is no vibration frequency that indicates an abnormality in a specific part. It cannot be used well when desired.
  • the present invention relates to a machine tool bearing quality determination method and system for determining the quality of a bearing that rotatably supports a spindle in a machine tool that processes a workpiece via a rotary tool attached to the spindle. be.
  • This method for judging whether the bearing is good or bad includes the steps of detecting rotational vibration of the bearing when the spindle is idling; analyzing the rotational vibration by Fourier series expansion to obtain the vibration frequency; A total SRF that is the sum of the spindle rotation frequency (SRF) calculated from and its harmonics (integer multiples of the spindle rotation frequency), and a residual frequency (Non-SRF) obtained by removing the total SRF from all the vibration frequencies , and a step of determining whether the bearing is good or bad by comparing the total sum SRF and the residual frequency.
  • SRF spindle rotation frequency
  • Non-SRF residual frequency
  • a vibration detection mechanism detects rotational vibration of the bearing
  • a calculation mechanism analyzes the rotational vibration by Fourier series expansion and obtains the vibration frequency
  • the vibration frequency is The total SRF, which is the sum of the spindle rotation frequency (SRF) calculated from the spindle rotation speed/60 and its harmonics (integer multiples of the spindle rotation frequency), and the residual frequency obtained by removing the total SRF from all the vibration frequencies (Non-SRF), and a frequency dividing mechanism for dividing into (Non-SRF), and a comparing and judging mechanism for judging the quality of the bearing by comparing the total SRF and the residual frequency.
  • SRF spindle rotation frequency
  • the vibration frequency of the bearing when the spindle is idling is divided into the total SRF (spindle rotation frequency) and the remaining residual frequency (Non-SRF),
  • SRF spindle rotation frequency
  • Non-SRF residual frequency
  • FIG. 1 is a schematic explanatory diagram of a machine tool to which a bearing quality determination system according to an embodiment of the present invention is applied;
  • FIG. 3 is an explanatory diagram of a controller that constitutes the bearing quality determination system;
  • FIG. 4 is an explanatory diagram of a display unit that constitutes the bearing quality determination system; It is explanatory drawing of various dimensions of a bearing. It is explanatory drawing which shows the vibration data of the said bearing before exchange. It is explanatory drawing which shows the vibration data of the said bearing after exchange.
  • a bearing quality determination system 10 is applied to a machine tool 12.
  • the machine tool 12 includes a spindle (main shaft) 18 rotatably provided in a housing 14 via a pair of front bearings 16f and a pair of rear bearings 16b.
  • a tool holder (rotary tool) 20 is detachably attached to the spindle 18 , and a cutter 22 is attached to the tip of the tool holder 20 .
  • the bearing quality determination system 10 includes an acceleration sensor (vibration detection mechanism) ( Alternatively, a microphone) 24 for acquiring vibration sound by sound waves is provided. This is because in the case of the front bearing 16f and the rear bearing 16b that support the spindle 18, usually the front bearing 16f is likely to malfunction. Note that the acceleration sensor 24 may be arranged adjacent to the rear bearing 16b.
  • the acceleration sensor 24 is connected to a rotational vibration measuring instrument (hereinafter referred to as controller) 28 via a signal line 26, and the controller 28 is connected to a machine tool control panel 30 as shown in FIG.
  • the machine tool control panel 30 has a function of controlling the machine tool 12 .
  • the controller 28 includes a computation unit (computation mechanism) 34 that amplifies the rotational vibration (idling vibration) of the front bearing 16f detected by the acceleration sensor 24 using an amplifier and filter circuit 32 and captures the amplified vibration.
  • the arithmetic unit 34 is connected to an input setting unit 36 for inputting the inner and outer ring dimensions of the front bearing 16f, the number of balls of the rolling elements, the ball diameter, the contact angle, and the like (to be described later).
  • the input setting unit 36 can set thresholds for monitoring and identification determination, signal processing procedures when vibration exceeding the thresholds occurs, and the like.
  • a rotational vibration judgment unit 38 and an input/output unit 40 for outputting a signal subjected to arithmetic judgment processing are connected to the arithmetic unit 34 .
  • a display unit 42 is connected to the calculation unit 34 to display the calculation result, the detection result, and the like on the screen. Updated data is typically sent from the arithmetic unit 34 to the rotational vibration determination unit 38 every second.
  • Arithmetic unit 34 functions as a frequency division mechanism that divides the frequency spectrum into summed SRF and residual frequency (Non-SRF), as will be described later.
  • the display unit 42 includes a total power display window 44, a frequency spectrum display window 46, a non-SRF/SRF comparison display window 48, and a history display window 50. Above the display unit 42, a Measuring lamp 52a, a Watching lamp 52b, and a spindle rotation speed display 52c are provided.
  • the total power display window 44 is a vibration amount monitoring unit that is turned on by a measurement start button of the controller 28 or a signal from the device.
  • the total power display window 44 displays the total power (G 2 ) of rotational vibration that changes with the idling of the spindle 18 (and, if necessary, machining). , is displayed as total power in real time.
  • the sum of the squared acceleration values is displayed on the vertical axis, and the elapsed time (seconds) is displayed on the horizontal axis.
  • acquired data for 20 seconds from the start of measurement (Measuring lamp 52a turns ON) is displayed.
  • the period from the start of measurement to 7 seconds is the time zone for obtaining the idling signal, and the period from 2 seconds to 5 seconds after the start of measurement is the time period for monitoring vibration (the Watching lamp 52b is ON).
  • the period from 7 seconds to 17 seconds after the start of measurement is machining vibration, and the period from 17 seconds to 20 seconds is idle vibration.
  • a sign threshold 54 for displaying a sign that the total power enters the warning range, an alarm threshold 56 for displaying that the total power has increased abnormally, and a vibration monitoring time zone. are separately set by the input setting unit 36 .
  • the signal is transmitted to the outside via the input/output unit 40 .
  • the frequency spectrum display window 46 displays the frequency spectrum obtained by Fourier transforming the rotational vibration during idling.
  • the frequency spectrum display window 46 displays a spectrum with acceleration (G or m/s 2 ) or displacement ( ⁇ m) on the vertical axis and frequency (Hz) calculated by Fourier transform on the horizontal axis.
  • the display range of the horizontal axis of the spectrum is selected and set in advance from 10 Hz to 10,000 Hz, and generally selected ranges such as 10 Hz to 2,000 Hz and 10 Hz to 2,500 Hz.
  • the display on the vertical axis is the automatic gain method. Acceleration (m/s 2 ), velocity (m/s), or displacement ( ⁇ m) units can be selected for spectrum display.
  • the frequency spectrum display window 46 vertical lines indicating the spindle-revolving-frequency (hereinafter referred to as SRF) of the spindle 18 calculated from the spindle rotation speed rpm/60 (Hz) and its harmonics are displayed. be done. This is for facilitating determination of whether or not SRF is included in rotational vibration.
  • the spindle rotation speed rpm is taken into the arithmetic unit 34 via the input/output unit 40 in advance.
  • the frequency spectrum display window 46 data such as the inner and outer ring dimensions of the front bearing 16f, the number of balls of the rolling elements, the ball diameter, the contact angle, etc. separately set by the input setting unit 36, and the main shaft rotation speed rpm , vertical lines of frequencies that are likely to occur due to damage to the inner and outer rings and rolling elements are displayed.
  • the comparison display window 48 functions as a comparison and judgment mechanism for judging the quality of the front bearing 16f by displaying the relative ratio between the total SRF and the residual frequency as it changes over time.
  • the amount of change (comparison ratio ) is displayed as a dot graph over time (every second). In this dot graph, when the total amount of SRF during rotational vibration is large, it is displayed in the lower part, while when the total amount of Non-SRF is large, it is displayed in the upper part.
  • a sign threshold 58 for judging that the front bearing 16f has entered a pre-damage sign stage and an abnormality for judging that the front bearing 16f is damaged Threshold 60 and are separately set by the input setting unit 36 .
  • an alarm is output to the outside to alert an operator or the like.
  • the alarm display color and alarm flashing interval are changed to distinguish whether the alarm is caused by the total power display value or the comparison ratio display value. ing.
  • the total amount of rotational vibration is displayed as a bar graph in chronological order during the vibration monitoring time period in the process with the separately set sequence number.
  • the change over time of the bar graph makes it possible to confirm the change over time of the total amount of rotational vibration when the spindle 18 idles.
  • the history display window 50 is provided with arrow buttons 62a and 62b positioned on the left side of the bar graph, and by appropriately pressing the arrow buttons 62a and 62b, the total amount of past rotational vibrations can be confirmed.
  • a threshold value is separately set by the input setting unit 36 as necessary in the history display window 50, and an alarm is output to the outside when the total amount exceeds the threshold value.
  • the front bearing 16f (and the rear bearing 16b) that supports the spindle 18 for example, precision bearings set to the conditions (dimensions, etc.) shown in FIG. 4 are used. Then, precision machining is performed by the machine tool 12 using the front bearing 16f and the rear bearing 16b. Specifically, as shown in FIG. 1, a spindle 18 having a tool holder 20 having a cutter 22 attached to its tip is rotationally driven, and the tool holder 20 moves along a work (not shown). As a result, the cutter 22 rotates integrally with the tool holder 20, and the workpiece (not shown) is machined (precision machined) through the cutter 22. As shown in FIG.
  • the front bearing 16f and the rear bearing 16b that support the spindle 18 are particularly prone to damage, which may affect the machining accuracy. Therefore, the front bearing 16f and the rear bearing 16b are usually replaced with new bearings after the machining operation has been performed for a predetermined time (preferably before the front bearing 16f is damaged).
  • the applicant measured the vibration accompanying the main shaft rotation (2000 rpm) in the front bearing 16f after use (immediately before replacement), and the vibration data shown in FIG. 5 was obtained. . Specifically, significant frequency peaks appeared at 101 Hz, 198 Hz, 391 Hz, 587 Hz, 1256 Hz and 1504 Hz.
  • the applicant found that the front bearing 16f before and after replacement had a significant difference in the frequency of vibration due to rotation. That is, the difference depends on whether or not a significant vibration frequency appears in the signal of the spindle rotation frequency (SRF).
  • SRF spindle rotation frequency
  • the rotational vibration of the front bearing 16f that supports the spindle 18 is measured while the spindle 18 is idling before starting machining or during daily warm-up.
  • the acceleration sensor 24 acquires rotational vibration of the front bearing 16f during idling of the spindle 18 in the controller 28 during the vibration monitoring time period.
  • the acquired rotational vibration is taken into the arithmetic unit 34 via the amplifier and filter circuit 32 .
  • arithmetic analysis by Fourier transform is performed on the captured slip vibration. Specifically, the time oscillation f(t) is
  • f(t) ⁇ (a j cos2 ⁇ Jt+b j sin2 ⁇ Jt). Note that a j is the cosine harmonic component Fourier coefficient of frequency J, and b j is the sine harmonic component Fourier coefficient of frequency J.
  • the integration interval is from 0 to T, and the integration interval T is an integer multiple of the cycle 1/J.
  • the display unit 42 is provided with a total power display window 44, a frequency spectrum display window 46 and a non-SRF/SRF comparison display window 48, and the frequency spectrum calculated by Fourier analysis is displayed. , depending on the purpose, are displayed in these.
  • the magnitude of the vibration amount that changes as the spindle 18 idles is displayed as a real-time total power (G 2 ).
  • the vertical axis represents the total power (G 2 ) obtained by squaring the acceleration, and the increase/decrease ratio of the amount of idling vibration is represented as a large amount of change. That is, small vibrations are displayed smaller and large vibrations are displayed larger. For this reason, the total power energy, which is difficult to discern from the frequency spectrum, can be discriminated, thereby expressing rotational vibration (furthermore, machining vibration) during idling of the spindle 18, and increasing or decreasing the vibration, etc., can be sharply represented.
  • the rotational vibration of the front bearing 16f can be acquired at any time while the spindle 18 is idling. Acquiring and recording the data is easier to compare.
  • the frequency spectrum display window 46 displays the frequency spectrum obtained by Fourier transforming the rotational vibration.
  • the amount of change in the relative ratio between the total SRF in rotational vibration and the total non-SRF is displayed as a dot graph. Elapsed time (every second) is displayed. In this dot graph, when the total amount of SRF during rotational vibration is large, that is, when the front bearing 16f is in a good state, it is displayed at the bottom. It is displayed above that the front bearing 16f is in the no condition.
  • the controller 28 processes rotational vibration of the front bearing 16f when the spindle 18 idles.
  • the frequency spectrum display window 46 for example, a large amount of non-SRF total sum appears during rotational vibration, and the relative ratio in the comparison display window 48 may exceed the indication threshold 58 . Therefore, it is determined that the front bearing 16f has entered the premonitory stage of damage determination, and the replacement work of the front bearing 16f is started. Furthermore, in the total power display window 44, the total power value is large. As a result, it is determined that the front bearing 16f is worn, and it can be confirmed that the spindle 18 is rotating normally in the premonitory stage.
  • the front bearing 16f may have no damage to each part, or may have slight damage.
  • the operator can replace the front bearing 16f in a desired state. Also, the operator can arbitrarily set the abnormality threshold 60 .
  • the present embodiment it is possible to macroscopically detect the quality of the front bearing 16f in a list simply by observing the magnitude of the comparison ratio displayed in the comparison display window 48. That is, it is only necessary to use SRF vibration and non-SRF vibration with the main shaft rotation speed rpm as a parameter, and it is possible to perform a simple control to determine whether the front bearing 16f is good or bad, that is, to determine the replacement timing with high accuracy and efficiency. Become.
  • an omen threshold 58 is set in the comparison display window 48 .

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Acoustics & Sound (AREA)
  • Testing Of Devices, Machine Parts, Or Other Structures Thereof (AREA)

Abstract

Le problème à résoudre dans le cadre de la présente invention est de permettre de déterminer avec précision la qualité d'un palier à l'aide d'un procédé et d'une configuration simples. La solution selon la présente invention porte sur un procédé qui comprend : une étape consistant à détecter une vibration de rotation d'un palier ; une étape consistant à obtenir une fréquence de vibration par analyse de la vibration de rotation au moyen d'une expansion en série de Fourier ; une étape consistant à diviser la fréquence de vibration en un SRF total et une fréquence résiduelle ; et une étape consistant à déterminer la qualité du palier par comparaison du SRF total et de la fréquence résiduelle.
PCT/JP2022/039805 2021-10-14 2022-10-14 Procédé et système de détermination de qualité de palier de machine de travail WO2023063435A1 (fr)

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JP2021182874 2021-10-14

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Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS62193751A (ja) * 1986-02-19 1987-08-25 Ichiro Inazaki 多刃工具損傷検出装置
JP2006234786A (ja) * 2005-01-26 2006-09-07 Nsk Ltd 機械設備の異常診断装置及び異常診断方法
JP2018040594A (ja) * 2016-09-05 2018-03-15 オークマ株式会社 回転軸装置及び回転軸装置における軸受の異常判定方法
JP2020003363A (ja) * 2018-06-28 2020-01-09 オークマ株式会社 転がり軸受の異常診断方法及び異常診断装置、異常診断プログラム
CN110907162A (zh) * 2019-12-13 2020-03-24 北京天泽智云科技有限公司 一种变转速下无转速计的旋转机械故障特征提取方法
JP2020056801A (ja) * 2020-01-10 2020-04-09 中国電力株式会社 計測診断装置、及び計測診断方法
WO2021075584A1 (fr) * 2019-10-18 2021-04-22 エヌティーエンジニアリング株式会社 Procédé et système de surveillance de l'état de travail d'une machine de travail

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS62193751A (ja) * 1986-02-19 1987-08-25 Ichiro Inazaki 多刃工具損傷検出装置
JP2006234786A (ja) * 2005-01-26 2006-09-07 Nsk Ltd 機械設備の異常診断装置及び異常診断方法
JP2018040594A (ja) * 2016-09-05 2018-03-15 オークマ株式会社 回転軸装置及び回転軸装置における軸受の異常判定方法
JP2020003363A (ja) * 2018-06-28 2020-01-09 オークマ株式会社 転がり軸受の異常診断方法及び異常診断装置、異常診断プログラム
WO2021075584A1 (fr) * 2019-10-18 2021-04-22 エヌティーエンジニアリング株式会社 Procédé et système de surveillance de l'état de travail d'une machine de travail
CN110907162A (zh) * 2019-12-13 2020-03-24 北京天泽智云科技有限公司 一种变转速下无转速计的旋转机械故障特征提取方法
JP2020056801A (ja) * 2020-01-10 2020-04-09 中国電力株式会社 計測診断装置、及び計測診断方法

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