WO2021075584A1 - Procédé et système de surveillance de l'état de travail d'une machine de travail - Google Patents

Procédé et système de surveillance de l'état de travail d'une machine de travail Download PDF

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Publication number
WO2021075584A1
WO2021075584A1 PCT/JP2020/039804 JP2020039804W WO2021075584A1 WO 2021075584 A1 WO2021075584 A1 WO 2021075584A1 JP 2020039804 W JP2020039804 W JP 2020039804W WO 2021075584 A1 WO2021075584 A1 WO 2021075584A1
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Prior art keywords
machining
display window
frequency
vibration
tpf
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PCT/JP2020/039804
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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
Priority to CN202080072846.XA priority Critical patent/CN114555291A/zh
Priority to DE112020004994.9T priority patent/DE112020004994T5/de
Publication of WO2021075584A1 publication Critical patent/WO2021075584A1/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
    • B23Q17/09—Arrangements for observing, indicating or measuring on machine tools for indicating or measuring cutting pressure or for determining cutting-tool condition, e.g. cutting ability, load on tool
    • B23Q17/0952—Arrangements for observing, indicating or measuring on machine tools for indicating or measuring cutting pressure or for determining cutting-tool condition, e.g. cutting ability, load on tool during machining
    • 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
    • B23Q17/09—Arrangements for observing, indicating or measuring on machine tools for indicating or measuring cutting pressure or for determining cutting-tool condition, e.g. cutting ability, load on tool
    • B23Q17/0952—Arrangements for observing, indicating or measuring on machine tools for indicating or measuring cutting pressure or for determining cutting-tool condition, e.g. cutting ability, load on tool during machining
    • B23Q17/0971—Arrangements for observing, indicating or measuring on machine tools for indicating or measuring cutting pressure or for determining cutting-tool condition, e.g. cutting ability, load on tool during machining by measuring mechanical vibrations of parts of the machine
    • B23Q17/0976—Detection or control of chatter
    • 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
    • B23Q17/09—Arrangements for observing, indicating or measuring on machine tools for indicating or measuring cutting pressure or for determining cutting-tool condition, e.g. cutting ability, load on tool
    • B23Q17/0952—Arrangements for observing, indicating or measuring on machine tools for indicating or measuring cutting pressure or for determining cutting-tool condition, e.g. cutting ability, load on tool during machining
    • B23Q17/0971—Arrangements for observing, indicating or measuring on machine tools for indicating or measuring cutting pressure or for determining cutting-tool condition, e.g. cutting ability, load on tool during machining by measuring mechanical vibrations of parts of the machine
    • 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
    • B23Q17/09—Arrangements for observing, indicating or measuring on machine tools for indicating or measuring cutting pressure or for determining cutting-tool condition, e.g. cutting ability, load on tool
    • B23Q17/0952—Arrangements for observing, indicating or measuring on machine tools for indicating or measuring cutting pressure or for determining cutting-tool condition, e.g. cutting ability, load on tool during machining
    • B23Q17/098—Arrangements for observing, indicating or measuring on machine tools for indicating or measuring cutting pressure or for determining cutting-tool condition, e.g. cutting ability, load on tool during machining by measuring noise
    • 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
    • B23Q17/09—Arrangements for observing, indicating or measuring on machine tools for indicating or measuring cutting pressure or for determining cutting-tool condition, e.g. cutting ability, load on tool
    • B23Q17/0995—Tool life management
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B19/00—Programme-control systems
    • G05B19/02—Programme-control systems electric
    • G05B19/18—Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form
    • G05B19/406—Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form characterised by monitoring or safety
    • G05B19/4065—Monitoring tool breakage, life or condition
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B2219/00—Program-control systems
    • G05B2219/30—Nc systems
    • G05B2219/37—Measurements
    • G05B2219/37434—Measuring vibration of machine or workpiece or tool

Definitions

  • the present invention relates to a machining state monitoring method and a system of a work machine that monitors the machining state of the work when the machining process is performed on the work via a rotary tool.
  • various machine tools are used to process a work piece via a processing tool.
  • a boring tool provided with a boring cutter (cutting edge) is attached to a rotating spindle of a machine tool, and the boring tool is sequentially rotated along a pilot hole while rotating at a high speed.
  • a highly accurate hole is machined at a predetermined position with the cutting edge machining diameter.
  • a method and an apparatus for suppressing chattering of a work machine disclosed in Patent Document 1 are known.
  • this chatter suppression method a step of detecting vibration generated when the rotation of a machining tool or a workpiece is started, a step of setting a vibration at the time of idling of the machine spindle as a threshold value, and a step of machining the machine spindle.
  • vibration is detected from the start of rotation, and the vibration is analyzed by Fourier series expansion. Since the Fourier series expansion is simple in operation and can be processed quickly, the immediacy is improved well, and it is possible to predict the chatter vibration before the chatter actually grows. Therefore, it becomes possible to recognize the regeneration chatter in which the vibration grows from zero with the start of rotation at the early stage of the sign. As a result, the rotation speed of the machine spindle can be adjusted before the effect of chatter actually occurs, and the occurrence of regenerated chatter can be reliably suppressed.
  • the present invention has been made in connection with the above technical idea, and provides a machining state monitoring method and system for a work machine capable of detecting various machining states with high accuracy and efficiency with a simple process and configuration.
  • the purpose is to provide.
  • the present invention relates to a machining state monitoring method and a system of a work machine that monitors the machining state of the work when the machining process is performed on the work via a rotary tool.
  • This machining state monitoring method includes a step of detecting machining vibration during machining with a rotary tool, a step of analyzing the machining vibration by Fourier series expansion, and a step of obtaining a machining frequency (frequency of machining vibration generated during machining).
  • the machining frequency includes the tool passing frequency (TPF) (Tool-Passing-Frequency), which is the sum of the fundamental wave calculated from the spindle rotation speed x the number of blades ⁇ 60 and its harmonics (an integral multiple of the fundamental wave).
  • TPF tool passing frequency
  • the machining state of the work is monitored by comparing and displaying the step of dividing into the residual frequency (NON-TPF) obtained by removing the tool passing frequency from the machining frequency and the tool passing frequency and the residual frequency. It has a process.
  • this vibration monitoring system has a vibration detection mechanism that detects machining vibration during machining with a rotating tool, and a calculation that analyzes the machining vibration by Fourier series expansion to obtain the machining frequency (frequency of machining vibration generated during machining).
  • the mechanism and the machining frequency are the fundamental wave calculated from the spindle rotation speed ⁇ the number of blades ⁇ 60 and the tool passing frequency (TPF) (Tool-Passing-Frequency) which is its harmonic (an integral multiple of the fundamental wave).
  • TPF tool passing frequency
  • Tool-Passing-Frequency Tool-Passing-Frequency
  • the work can be used. It is equipped with a frequency comparison display mechanism that monitors the processing status.
  • the machining frequency (frequency of machining vibration) is set to the tool passing frequency (TPF) and other residual frequencies (TPF). It is possible to monitor various machining states of the work only by dividing it into two parts (NON-TPF) and comparing and displaying the tool passing frequency and the residual frequency.
  • machining quality can be determined simply by using TPF vibration and NON-TPF vibration with two parameters, the spindle speed and the number of blades, and the quality of the machining state can be judged with high accuracy and efficiency. Become feasible.
  • FIG. 1 is a schematic explanatory view of a machine tool to which the machining state monitoring system of the work machine according to the first embodiment of the present invention is applied.
  • FIG. 2 is an explanatory diagram of a controller constituting the machining state monitoring system.
  • FIG. 3 is an explanatory diagram of a display unit constituting the machining state monitoring system.
  • FIG. 4 is a comparative explanatory view of a case where the quality of the cutting state is indicated by the current value of the cutting load and a case where the quality of the cutting state is indicated by the second embodiment of the present invention.
  • FIG. 5 is an explanatory diagram showing a frequency spectrum in the processing vibration of the third embodiment of the present invention.
  • the machining condition monitoring system 10 is applied to the machine tool 12.
  • the machine tool 12 is applied to a work machine of a system in which an acceleration sensor 26, a microphone 28, and a controller 30, which will be described later, are functionally integrated.
  • the machine tool 12 includes a spindle (spindle) 18 rotatably provided in the housing 14 via a bearing 16 and a tool holder (rotary tool) 20 detachable from the spindle 18.
  • a cutter 22 is attached to the tip of the tool holder 20.
  • the work W is placed on the work table 24.
  • the machining condition monitoring system 10 is an acceleration sensor (vibration detection mechanism) mounted on the side of the housing 14 in order to detect vibration when the spindle 18 is idling and vibration generated when machining by the cutter 22 is started. ) 26 or at least one of a microphone (vibration detection mechanism) 28 that acquires vibration sound by sound waves.
  • the acceleration sensor 26 and / or the microphone 28 are connected to the controller 30, and the controller 30 is connected to the machine tool control panel 32.
  • the machine tool control panel 32 controls the machine tool 12 and is connected to the control operation panel 34.
  • the controller 30 includes an arithmetic unit (arithmetic mechanism) 38 that amplifies and captures mechanical vibration (machining vibration) detected by the acceleration sensor 26 and / or the microphone 28 by an amplifier and a filter circuit 36. Be prepared.
  • An input setting unit 40 for inputting the rotation speed of the spindle 18, the number of blades of the cutter 22, the natural frequency, and the like is connected to the calculation unit 38.
  • a threshold value for monitoring and identification determination, a signal processing procedure when vibration exceeding the threshold value occurs, and the like can be set.
  • the input setting unit 40 is provided with a repeat counter (circuit) 42 as needed.
  • a processing state determination unit 44 and an input / output unit 46 for outputting a signal processed for arithmetic determination processing, which will be described later, are connected to the arithmetic unit 38.
  • Information on the spindle speed RPM and the tool number in use is taken into the arithmetic unit 38 from the machine tool control panel 32 through the input / output unit 46, and can be read from the NC program at any time.
  • a display unit 48 for displaying the calculation result, the detection result, etc. on the screen is connected to the calculation unit 38. Updated data is normally sent from the arithmetic unit 38 to the machining state determination unit 44 every second.
  • the display unit 48 includes a total power display window 51, a frequency spectrum display window 52, a TPF vibration display window 53, a NON-TPF vibration display window 54, and a change display window 55.
  • screen selection buttons 56 and 57 used for switching between the display screen and the threshold value input screen are provided.
  • the arithmetic unit 38 functions as a frequency division mechanism that divides the frequency spectrum into a tool passing frequency and a surplus frequency, as will be described later.
  • the total power display window 51 is a vibration amount monitoring unit that is turned on by a signal from the measurement start button of the controller 30 or the device.
  • the total power display window 51 displays the total power (G 2 ) of the vibration that changes with processing, and displays the magnitude of the vibration amount in each time zone as the total power having real-time characteristics.
  • the total power display window 51 the sum of the squared values of acceleration is represented on the vertical axis, and the elapsed time (seconds) is represented on the horizontal axis.
  • the total power display window 51 has, if necessary, a sign threshold value 61 that displays a sign that the total power enters the warning area, and an alarm threshold value 62 that displays that the total power has risen abnormally. Set.
  • the frequency spectrum display window 52 displays the frequency spectrum obtained by Fourier transforming the processing vibration.
  • a spectrum is displayed with the acceleration (G or m / s 2 ) on the vertical axis and the frequency (Hz) calculated by the Fourier transform on the horizontal axis.
  • the display range on the horizontal axis of the spectrum is selected and set in advance from 10 Hz to 10,000 Hz, and generally, 10 Hz to 2,000 Hz, 10 Hz to 2,500 Hz, or 10 Hz to 4,000 Hz, which satisfactorily represent the processing state. Etc. are selected.
  • the vertical axis is displayed by the automatic gain method.
  • the frequency spectrum display window 52 is set with an alarm threshold value 63 and a limited band threshold line 69, if necessary.
  • the threshold line 69 can be set in a specific frequency band, and in the setting of the threshold value of this frequency band, the setting of the frequency band and the height can be set on a separate input setting screen (not shown). It can be carried out.
  • the TPF vibration display window 53 displays the tool passing frequency (Tool-Passing-Frequency) (hereinafter referred to as TPF) in the frequency spectrum displayed on the frequency spectrum display window 52.
  • TPF is the sum of the fundamental wave and its harmonics (integer multiples of the fundamental wave) calculated from the spindle speed ⁇ the number of blades ⁇ 60.
  • the acceleration (G or m / s 2 ) is represented by the vertical axis
  • the frequency (Hz) is represented by the horizontal axis.
  • An alarm threshold value 64 is set in the TPF vibration display window 53, if necessary.
  • the NON-TPF vibration display window 54 displays a surplus frequency (hereinafter referred to as NON-TPF) from which the TPF has been removed from the frequency spectrum displayed on the frequency spectrum display window 52.
  • NON-TPF a surplus frequency
  • the acceleration (G or m / s 2 ) is represented by the vertical axis
  • the frequency (Hz) is represented by the horizontal axis.
  • An alarm threshold value 65 and a threshold line 68 in a limited band are set in the NON-TPF vibration display window 54, if necessary.
  • the threshold line 68 can be set in a specific frequency band, and in setting the threshold value in this frequency band, the frequency band and the height are set separately. It can be done on the input setting screen (not shown).
  • the change display window 55 functions as a frequency comparison display mechanism for monitoring the machining state of the work W by comparing and displaying TPF and NON-TPF.
  • the relative ratio of the total amount of TPF displayed on the TPF vibration display window 53 to the total amount of NON-TPF displayed on the NON-TPF vibration display window 54 (total amount of NON-TPF).
  • the amount of change in / TPF total amount) is displayed as a dot graph over time (per second). In this dot graph, the lower the value, the better the cutting, while the higher the value, the worse the machinability and the occurrence of chatter.
  • the change display window 55 has, if necessary, a predictive threshold value 66 for determining that the process has entered the predictive stage of determining the quality of processing, and at least an upper limit for determining whether or not a processing abnormality has occurred.
  • a threshold value 67a or a lower limit threshold value 67b is set.
  • a separate input screen (not shown) is used for inputting the threshold value, and this input screen is displayed by operating the screen selection button 57.
  • the machining status monitoring method by the machining status monitoring system 10 configured in this way will be described below.
  • the spindle 18 to which the tool holder 20 having the cutter 22 attached to the tip thereof is attached is rotationally driven and is fed out along the pilot hole of the work W. Then, the tool holder 20 moves relatively to the pilot hole side of the work W. Therefore, the cutter 22 rotates integrally with the tool holder 20, and the inner wall surface of the work W is processed via the cutter 22.
  • the vibration of the spindle 18 when idling is acquired by the acceleration sensor 26 and / or the microphone 28, and this value is set as an allowable value (threshold value). Then, the vibration of the spindle 18 is taken into the arithmetic unit 38 via the amplifier and the filter circuit 36. When the captured vibration exceeds the permissible value, the arithmetic unit 38 determines that machining has started. That is, the calculation unit 38 functions as a machining start detection mechanism for detecting that the machining of the work W has started.
  • the machining start detection mechanism is, for example, a mechanism for detecting that a predetermined time has elapsed from the start of rotation of the spindle 18 or a mechanism for detecting that the feeding distance of the spindle 18 has reached a predetermined distance. You may.
  • arithmetic analysis by Fourier transform is performed on the processed vibration captured via the amplifier and the filter circuit 36. Specifically, the time vibration f (t) is
  • f (t) ⁇ (a j cos 2 ⁇ Jt + b j sin2 ⁇ Jt).
  • a j is the cosine harmonic component Fourier coefficient of the frequency J
  • b j is the sinusoidal harmonic component Fourier coefficient of the frequency J.
  • the integration interval is 0 to T, and this integration interval T is an integral multiple of the period 1 / J.
  • the vibration frequency actually processed for example, 10 Hz to 10,000 Hz is acquired.
  • the display unit 48 is provided with a total power display window 51, a frequency spectrum display window 52, a TPF vibration display window 53, a NON-TPF vibration display window 54, and a change display window 55.
  • the frequency spectrum calculated by the analysis is displayed on these depending on the purpose.
  • the magnitude of the amount of vibration that changes with processing in each time zone is displayed as total power (G 2) having real-time performance.
  • the total power (G 2 ) obtained by squared the acceleration is displayed on the vertical axis, and the increase / decrease ratio of the processing vibration amount is expressed as a large change amount. That is, small vibrations are displayed smaller and large vibrations are displayed larger.
  • the value displayed in the total power display window 51 is a value obtained by squaring the waveform of the acceleration amplitude and integrating it in time axis units (usually 1 second), and includes all the acquired frequencies. Therefore, it is possible to discriminate the total power energy that is difficult to discriminate from the frequency spectrum, and it is possible to sensitively display the increase / decrease in cutting resistance, the increase / decrease in high-frequency vibration, and the like.
  • the frequency spectrum display window 52 displays the frequency spectrum obtained by Fourier transforming the processing vibration. Then, the TPF vibration display window 53 displays only the TPF among the frequency spectra displayed on the frequency spectrum display window 52, while the NON-TPF vibration display window 54 displays the TPF among the frequency spectra. The removed NON-TPF is displayed.
  • the amount of change in the total amount / total amount of TPF) is displayed as a dot graph over time (per second).
  • the lower the numerical value of the dot graph the better the cutting, while the higher the numerical value, the worse the machinability and the occurrence of chatter.
  • the first embodiment by observing the change amount of the change display window 55 up and down, it is possible to obtain the effect that the quality of the cutting state can be detected in a macro list. That is, it is possible to determine the quality of comprehensive machining simply by using TPF vibration and NON-TPF vibration with the two parameters of spindle speed and number of blades as parameters, and the quality of the machining state can be determined with simple control. Judgment can be performed with high accuracy and efficiency.
  • a sign threshold value 66 is set in the change display window 55.
  • the change display window 55 is provided with at least an upper limit threshold value 67a. Therefore, when the change ratio of the total amount of NON-TPF / the total amount of TPF rises abnormally and exceeds the upper limit threshold value 67a, an alarm signal is sent to the repeat counter 42 set separately. When the repeat counter 42 detects a signal input equal to or greater than the set integrated number, the macro alarm signal is displayed on the display unit 48 of the controller 30 and is output to the outside through the input / output unit 46.
  • the repeat counter 42 is provided to count the signal exceeding the alarm threshold value by the integrated value per unit time, it is not possible to determine an abnormal alarm for momentary noise or the like. If the repeat count value is set to 1, the abnormality determination is output when the alarm threshold value is exceeded once.
  • the change display window 55 is provided with at least a lower limit threshold value 67b. Therefore, when the change ratio of the total amount of NON-TPF / the total amount of TPF drops abnormally and falls below the lower limit threshold value 67b, an alarm signal is sent to the repeat counter 42 set separately.
  • the macroscopic processing state can be monitored by the change ratio of the total amount of NON-TPF / the total amount of TPF displayed on the change display window 55. Moreover, by combining the change of the change display window 55 with the change represented by the total power display window 51, the frequency spectrum display window 52, the TPF vibration display window 53 or the NON-TPF vibration display window 54, more accurate and detailed information can be obtained. It is possible to grasp various machining states (cutting state, abnormal state, etc.).
  • the change ratio of the total amount of NON-TPF / the total amount of TPF increases, and in the NON-TPF vibration display window 54, the threshold line of the limited band set in the high frequency vibration band.
  • the number may exceed 68. This indicates an increase in the high frequency component due to wear of the cutter 22, and can be used as an alarm signal for tool change.
  • FIG. 4 is a comparative explanatory view of a case where the quality of the cutting state is indicated by the current value of the cutting load and a case where the quality of the cutting state is indicated in the second embodiment of the present invention.
  • FIG. 4 shows the time course of vibration and current load from the first half of the machining without chattering to the second half of machining with regenerated chatter.
  • the display window 71 shows the total power during processing.
  • the current load amount of the spindle during processing is shown
  • the vertical axis shows the magnitude of the current load
  • the horizontal axis shows the time elapsed time.
  • the display window 73 divides the frequency spectrum of vibration into TPF vibration 73a and NON-TPF vibration 73b and represents them in an integrated display format.
  • the dark-colored portion of the first half represents the TPF vibration 73a
  • the light-colored portion of the second half represents the NON-TPF vibration 73b.
  • the TPF vibration 73a and the NON-TPF vibration 73b may be set to different colors or different shades from each other.
  • the display window 74 shows the state of change in the total amount of NON-TPF / the total amount of TPF.
  • the cutting process starts after 7.4 seconds, passes through a sign period of chattering after 11.3 seconds, and regenerated chatter occurs from 11.7 seconds to 13.4 seconds.
  • the display window 71 the change with time in the magnitude of the cutting vibration is remarkably displayed by the display of the total power.
  • chatter-free machining is performed, but in the second half of machining (between 11.7 seconds and 13.4 seconds), chattering occurs. Is occurring. At that time, the difference between the vibration amount in the first half and the vibration amount in the second half appears greatly.
  • the cutting load hardly fluctuates from the beginning to the end of machining. Therefore, it is not possible to satisfactorily detect various processing states such as the quality of processing.
  • the dark-colored portion TPF vibration 73a is displayed in the first half of the processing, while the light-colored portion NON-TPF vibration 73b is displayed in the second half of the processing. Has been done. Therefore, from this display, it is possible to clearly distinguish between the cutting region without chattering in the first half (TPF vibration 73a) and the state in which chattering occurs in the second half (NON-TPF vibration 73b). ..
  • the display window 74 shows the state of change in the total amount of NON-TPF / the total amount of TPF. From this display, it is shown that the numerical value is low and the machining condition is good in the first half of the machining, while the numerical value is high in the latter half of the machining and the transition from the defective state to the chattering is shown. , The change over time in the processing state can be easily determined.
  • FIG. 5 shows the frequency spectrum of machining vibration in the third embodiment of the present invention.
  • the vertical axis represents the magnitude of vibration (acceleration) (G or m / s 2 ), and the horizontal axis represents the frequency (Hz).
  • the cutting conditions are a spindle 18 rotation speed of 6200 rpm and a cutter 22 with four blades, and three remarkable vibration peaks are generated in the display window 81. Specifically, it is a peak frequency of 413 Hz (TPF1), which is a fundamental wave, and 826 Hz (TPF2) and 1240 Hz (TPF3), which are harmonics that are integral multiples of the fundamental wave.
  • TPF1 peak frequency of 413 Hz
  • TPF2 826 Hz
  • TPF3 1240 Hz
  • the display window 82 extracts and displays only the fundamental waves and harmonics (TPF1, TPF2 and TPF3) (TPF vibrations) from the vibrations of the frequency spectrum represented by the display window 81.
  • the display window 83 extracts and displays only the NON-TPF vibration from which the fundamental wave and the harmonics (TPF1, TPF2 and TPF3) are removed from the vibration of the display window 81.
  • the display window 84 shows the frequency spectrum at the time of the fluttering process that occurs after that, and the peak frequencies of 751 Hz and 1165 Hz are remarkable. This is a NON-TPF vibration.
  • the display window 85 extracts and displays only the TPF vibration from the vibrations of the frequency spectrum represented by the display window 84.
  • the display window 86 extracts and displays only the NON-TPF vibration from which the TPF vibration is removed from the vibration of the display window 84.
  • the cutting state can be accurately determined only by dividing the machining vibration into two, TPF vibration and NON-TPF vibration, and checking the difference between them. Similar to the display window 73 of FIG. 4, the two categories of TPF vibration and NON-TPF vibration can be represented by the integrated color difference or density difference. Further, similarly to the display window 74 of FIG. 4, it is also possible to express by two relative change ratios of TPF vibration and NON-TPF vibration.
  • the machining frequency is set to the tool passing frequency (TPF) and the other residual frequency (NON-TPF). It is possible to monitor various machining states of the work only by dividing it into two parts and comparing and displaying the tool passing frequency and the residual frequency.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Human Computer Interaction (AREA)
  • Manufacturing & Machinery (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Automation & Control Theory (AREA)
  • Automatic Control Of Machine Tools (AREA)
  • Machine Tool Sensing Apparatuses (AREA)
  • Numerical Control (AREA)
  • Testing Of Devices, Machine Parts, Or Other Structures Thereof (AREA)
  • Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)

Abstract

La présente invention comprend : une étape de détection de vibrations de travail au moment du travail; une étape d'obtention d'une fréquence de travail par analyse des vibrations de travail à l'aide d'une expansion en série de Fourier; une étape de division de la fréquence de travail en une fréquence de passage d'outil et en une fréquence résiduelle; et une étape de surveillance de l'état de fonctionnement par comparaison de la fréquence de passage d'outil et de la fréquence résiduelle et d'affichage des résultats de la comparaison.
PCT/JP2020/039804 2019-10-18 2020-10-15 Procédé et système de surveillance de l'état de travail d'une machine de travail WO2021075584A1 (fr)

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