CN109863376B

CN109863376B - Vibration monitoring method and system for work machine

Info

Publication number: CN109863376B
Application number: CN201780058842.4A
Authority: CN
Inventors: 驹井保宏
Original assignee: NT Engineering KK
Current assignee: NT Engineering KK
Priority date: 2016-09-28
Filing date: 2017-09-22
Publication date: 2021-07-02
Anticipated expiration: 2037-09-22
Also published as: JP2018054587A; CN109863376A; WO2018062445A1; JP6718107B2; DE112017004081T5

Abstract

The vibration monitoring method comprises the following steps: displaying the number of times that a TPF peak value serving as a peak acceleration at a tool passing frequency exceeds a TPF threshold value in a display column (56a) of a total threshold value exceeding display section (56); displaying the number of times that the harmonic TPF peak value at the harmonic frequency exceeds the harmonic TPF threshold value in display columns (56b-56d) of a total threshold value excess display unit (56); and displaying a comparison of the number of times the TPF threshold is exceeded with the number of times the harmonic TPF threshold is exceeded on a change display section (58).

Description

Vibration monitoring method and system for work machine

Technical Field

The present invention relates to a vibration monitoring method and system for a working machine for monitoring a state of vibration generated by a machining tool when machining is performed on a workpiece by the machining tool.

Background

In general, various machine tools are used to perform machining on a workpiece by means of a machining tool. For example, boring is to machine a high-precision hole portion at a predetermined position with a cutting edge machining diameter of a boring cutter (cutting edge) by attaching the boring cutter to a rotating spindle of a machine tool and continuously extending the boring cutter along a prepared hole while rotating the boring cutter at high speed.

In such a working machine, in order to perform high-precision machining, it is necessary to determine whether the machining state is good. Conventionally, whether the processing state is good or not is determined based on whether the processing sound (i.e., the cutting sound) is good or not. The sound and the vibration have the same source, and by detecting the characteristics of the machining vibration, it is possible to determine whether the machining state is good.

For example, a machining state monitoring method disclosed in patent document 1 includes: a normal state determining step of determining whether or not processing of the workpiece is in a normal state; a tremor determination step of determining whether tremor has occurred; a prediction stage determination step of determining that it is a prediction stage of transition from a normal state to a chattering when it is determined that the machining is not in the normal state and the chattering is not occurring; and a prediction stage monitoring step of monitoring a processing state of the prediction stage and displaying the processing state of the prediction stage on a screen when it is determined that it is the prediction stage. Therefore, by obtaining the characteristic information from the processing state at the prediction stage, it is possible to quickly and efficiently react before chatter occurs.

Reference list

Patent document

Patent document 1

Japanese laid-open unexamined patent application No.2016-083759

Disclosure of Invention

Technical problem to be solved by the invention

The present invention is achieved in view of the above technical ideas, and an object of the present invention is to provide a vibration monitoring method and system for a working machine, which are capable of efficiently performing determination of whether a machining state is good or not with high accuracy by simple steps and with a simple configuration.

Means for solving the problems

The present invention relates to a vibration monitoring method and system for a working machine, in which machining vibrations detected at the time of machining are expanded in a frequency spectrum including frequency and acceleration by fourier series expansion.

The vibration monitoring method comprises the following steps: comparing a TPF peak value serving as a peak acceleration at the tool passing frequency calculated from the number of revolutions and the number of blades of the machining tool with a TPF threshold value serving as a peak threshold value of the tool passing frequency preset for the frequency spectrum, and displaying the number of times that the TPF peak value exceeds the TPF threshold value on the TPF threshold value exceeding integrating and displaying section; comparing a harmonic TPF peak value serving as a peak acceleration at a harmonic frequency that is an integral multiple of the tool passing frequency with a harmonic TPF threshold value serving as a peak threshold value for a harmonic frequency preset for the spectrum, and displaying the number of times that the harmonic TPF peak value exceeds the harmonic TPF threshold value on the harmonic TPF threshold value exceeding integrating and displaying section; and comparing the number of times of exceeding the TPF threshold with the number of times of exceeding the harmonic TPF threshold, and displaying on the change display section.

In the vibration monitoring method, it is preferable that the harmonic TPF threshold exceeding integrating and displaying section has at least: a first harmonic TPF threshold excess accumulation and display section that displays the number of times a first harmonic TPF peak value at a harmonic frequency twice a tool passing frequency exceeds a harmonic TPF threshold; and a second harmonic TPF threshold excess accumulation and display section that displays the number of times a second harmonic TPF peak value at a harmonic frequency three times the tool pass frequency exceeds the harmonic TPF threshold; and the change display section compares and displays the number of times of exceeding the TPF threshold with a sum of at least two of the number of times of exceeding the first harmonic TPF threshold and the number of times of exceeding the second harmonic TPF threshold.

Further, the vibration monitoring system includes: a TPF threshold value excess accumulation and display section that compares a TPF peak value serving as a peak acceleration at a tool passing frequency calculated from the number of revolutions and the number of blades of the machining tool with a TPF threshold value serving as a peak threshold value of a tool passing frequency preset for the frequency spectrum, and displays the number of times that the TPF peak value exceeds the TPF threshold value; a harmonic TPF threshold excess accumulation and display section that compares a harmonic TPF peak value serving as a peak acceleration at a harmonic frequency that is an integral multiple of the tool passing frequency with a harmonic TPF threshold value serving as a peak threshold value of a harmonic frequency preset for the spectrum, and displays the number of times the harmonic TPF peak value exceeds the harmonic TPF threshold value; and a change display section that compares and displays the number of times that the TPF threshold is exceeded with the number of times that the harmonic TPF threshold is exceeded.

Further, in the vibration monitoring system, it is preferable that the harmonic TPF threshold exceeding accumulating and displaying section includes at least: a first harmonic TPF threshold excess accumulation and display section that displays the number of times a first harmonic TPF peak value at a harmonic frequency twice a tool passing frequency exceeds a harmonic TPF threshold; and a second harmonic TPF threshold excess accumulation and display section that displays the number of times a second harmonic TPF peak value at a harmonic frequency three times the tool pass frequency exceeds the harmonic TPF threshold; and the change display section compares and displays the number of times of exceeding the TPF threshold with a sum of at least two of the number of times of exceeding the first harmonic TPF threshold and the number of times of exceeding the second harmonic TPF threshold.

Effects of the invention

With the vibration monitoring method and system according to the present invention, when machining is performed on a workpiece by means of a machining tool, a correlation between the number of peaks occurring at a Tool Pass Frequency (TPF) and the number of peaks occurring at a harmonic frequency can be seen. In a good machining state, the number of peaks occurring at the tool pass frequency is significant, whereas in a poor machining state, the number of peaks occurring at the harmonic frequency increases along with the tool pass frequency. Therefore, from the change in the relationship between the two, it is possible to efficiently perform the determination of whether the machining state is good or not with high accuracy.

Drawings

Fig. 1 is a schematic illustration of a work machine to which a vibration monitoring system for a work machine according to an embodiment of the present invention is applied.

Fig. 2 is an illustrative diagram of a controller forming a vibration monitoring system.

Fig. 3 is an exemplary configuration diagram of a display unit forming the vibration monitoring system.

Fig. 4 is an exemplary diagram of good machining vibration displayed on a spectrum display portion forming a display unit.

Fig. 5 is an illustration of a spectrum obtained by fourier transform of the machining vibration shown in fig. 4.

Fig. 6 is an illustrative view of the defective machining vibration displayed on the frequency spectrum display section.

Fig. 7 is an illustration of a spectrum obtained by fourier transform of the machining vibration shown in fig. 6.

Fig. 8 is an exemplary view showing a change with time of the cumulative comparison value in a good machining state.

Fig. 9 is an exemplary view showing a change with time of the cumulative comparison value in a poor machining state.

Detailed Description

As shown in fig. 1, a machining state monitoring system (vibration monitoring system) 10 for a working machine according to an embodiment of the present invention is applied to a machine tool 12. The machine tool 12 is adapted to a working machine of a system in which an acceleration sensor 26, a microphone 28, and a controller 30 to be described later are functionally compiled.

The machine tool 12 includes: a spindle (main shaft) 18 rotatably disposed in the housing 14 by means of a bearing 16; and a tool holder (working tool) 20 attachable to and detachable from the spindle 18. A cutter 22 is mounted in the front end of the tool holder 20. The workpiece W is mounted on the table 24.

The machining state monitoring system 10 includes at least one of an acceleration sensor 26 mounted in a side portion of the housing 14 in order to detect vibration occurring at the start of machining by the tool 22, and a microphone 28 that acquires vibration sound by sound waves. The acceleration sensor 26 and/or the microphone 28 are connected to a controller 30, and the controller 30 is connected to a mechanical control panel 32. A machine control panel 32 controls the machine tool 12 and is connected to a control operation panel 34.

As shown in fig. 2, the controller 30 includes an arithmetic unit (arithmetic mechanism) 38 into which the mechanical vibration (machining vibration) detected by the acceleration sensor 26 and/or the microphone 28 is amplified by the amplifier and filter circuit 36 and taken.

An input setting unit (input setting section) 40 that inputs the number of revolutions of the spindle 18, the number of blades of the tool 22, the number of natural vibrations, and the like is connected to the arithmetic unit 38. In the input setting unit 40, a threshold value may be set for monitoring, recognizing, and determining a process of processing a signal or the like when vibration exceeding the threshold value occurs. In the input setting unit 40, a repetition counter (circuit) 42 is set as necessary.

A machining-state determining unit 44, and an input/output unit 46 for outputting an arithmetic determination signal to be described later are connected to the arithmetic unit 38. A display unit 48 that displays the arithmetic result, the detection result, and the like on a screen is connected to the arithmetic unit 38. The updated data is sent from the arithmetic unit 38 to the machining state determination unit 44 every second, for example.

As shown in fig. 3, the display unit 48 includes a spectrum display section 52, a threshold-exceeding integrating-sum display section 56, and a change display section 58. In the spectrum display section 52, a threshold value may be set for each frequency band or for each designated frequency. When vibration exceeding the set threshold occurs, the vibration is counted as exceeding the threshold, and the number of times the vibration is counted is cumulatively displayed on the threshold-exceeding integrating and displaying section 56. In the threshold-value-exceeding accumulation and display section 56, a first display field (TPF threshold-value-exceeding accumulation and display section) 56a, a second display field (harmonic TPF threshold-value-exceeding accumulation and display section) 56b, a third display field (harmonic TPF threshold-value-exceeding accumulation and display section) 56c, a fourth display field (harmonic TPF threshold-value-exceeding accumulation and display section) 56d, and a fifth display field 56e serving as multi-type display windows that operate together with an accumulation signal indicating the exceeding of a threshold value for a preset frequency band or for a specified frequency are provided. In the change display section 58, a change over time between the threshold value exceeding the accumulation and the value accumulated in the specified type display window of the display section 56 is displayed.

A vibration monitoring method performed by the thus formed machine state monitoring system 10 will be described below.

As shown in fig. 1, in the machine tool 12, a spindle 18 is driven to rotate and extend along a prepared hole Wa of a workpiece W, and a tool holder 20 having a tool 22 mounted at a front end thereof is attached to the spindle 18. Then, the tool rest 20 is relatively moved to the prepared hole Wa side of the workpiece W. Therefore, the tool 22 rotates integrally with the tool rest 20, and the inner wall surface of the workpiece W is machined by the tool 22.

Before starting the machining, the controller 30 acquires the vibrations of the spindle 18 at idle from the acceleration sensor 26 and/or the microphone 28. This vibration value is the vibration amount in the unloaded state and serves as a setting threshold value of the vibration level acquired later. Machining is started by the spindle 18 and machining vibrations are taken into the arithmetic unit 38 by means of the amplifier and filter circuit 36. In the arithmetic unit 38, the machining vibration is arithmetically analyzed via fourier transform (fourier series expansion). Specifically, the temporal vibration f (t) is expressed as:

f(t)＝Σ(a_j cos2πJt+b_j sin2πJt)

in this regard, a_jIs a Fourier coefficient of a cosine harmonic component of frequency J, and b_jAre the fourier coefficients of the sinusoidal harmonic components of frequency J.

Fourier coefficients with respect to frequency J are based on a_j1/2T ═ f (T) cos (2 pi Jt) dt and b_jT ═ 1/2T ^ f (T) sin (2 pi Jt) dt, a fourier series expansion is performed. The integration interval is 0 to T, and the integration interval T is an integer multiple of period 1/J. Here, the vibration frequency of the processing of, for example, 10Hz to 10000Hz is actually acquired.

As shown in fig. 3, a spectrum display section 52 is provided in the display unit 48. The frequency spectrum display unit 52 displays the frequency spectrum with the frequency Hz calculated by fourier analysis as the horizontal axis and the acceleration (intensity of vibration) G as the vertical axis.

The frequency spectrum display unit 52 displays various machining vibrations. For example, fig. 4 shows the machining vibration in a good machining state, and fig. 6 shows the machining vibration in a state where machining is rough (a poor machining state). Hereinafter, a detailed description will be given.

The machining vibration shown in fig. 4 occurs when an iron member is used as the workpiece W, and the machining is performed by the double-bladed cutter 22 at a spindle rotation speed of 3800 RPM. Fig. 4 represents the machining vibration amount by the time axis (acceleration G as the vertical axis, and the number of seconds passed after the start of measurement as the horizontal axis), and fig. 5 represents the amount subjected to fourier transform as the frequency spectrum of each frequency (frequency Hz as the horizontal axis, and acceleration G as the vertical axis).

Here, the Tool Passing Frequency (TPF) at which the machining blade edge abuts against the workpiece W is obtained from "(RPM of the number of revolutions of the spindle/60) × the number of blades". As shown in fig. 5, the tool passing frequency is 127Hz (hereinafter, referred to as TPF 1). Further, the harmonic frequency twice (integral multiple) TPF1 is 253Hz (hereinafter, referred to as TPF2), the harmonic frequency three times (integral multiple) TPF1 is 380Hz (hereinafter, referred to as TPF3), and the harmonic frequency four times (integral multiple) TPF1 is 507Hz (hereinafter, referred to as TPF 4). Harmonic frequencies (TPFn) five or more times (integer multiples) TPF1 may be provided as desired.

In TPF1, TPF2, TPF3, and TPF4, a TPF1 peak, a TPF2 peak, a TPF3 peak, and a TPF4 peak, respectively, serving as peak acceleration (vibration intensity) occur. At this time, the other peaks among the TPF2 peak, the TPF3 peak, and the TPF4 peak, which are harmonic frequencies of the TPF1, have considerably smaller values than the magnitude of the TPF1 peak. Further, no large peak acceleration occurs at frequencies other than the TPF1 peak to TPF4 peak.

That is, when the frequency spectrum of the machining vibration is observed, only the peak acceleration (TPF1 peak) at the tool pass frequency (TPF1) appears significantly, and there is no other large vibration frequency. The machining performed in this state is good, and the machining sound of the machining (cutting) shows a good cutting sound, and a good machined surface is obtained.

Meanwhile, the machining vibration shown in fig. 6 occurs when an iron member is used as the workpiece W, and machining is performed by the double-bladed tool 22 at a spindle rotation speed of 3060 RPM. Fig. 6 represents the machining vibration amount by the time axis (acceleration G as the vertical axis, and the number of seconds elapsed after the start of measurement as the horizontal axis), and fig. 7 represents the amount subjected to fourier transform as the frequency spectrum of each frequency (frequency Hz as the horizontal axis, and acceleration G as the vertical axis).

Here, the Tool Passing Frequency (TPF) is 102Hz (hereinafter, referred to as TPF 1). Further, the harmonic frequency twice (integral multiple) TPF1 is 204Hz (hereinafter, referred to as TPF2), the harmonic frequency three times (integral multiple) TPF1 is 306Hz (hereinafter, referred to as TPF3), and the harmonic frequency four times (integral multiple) TPF1 is 408Hz (hereinafter, referred to as TPF 4). Harmonic frequencies (TPFn) five or more times (integer multiples) TPF1 may be provided as desired.

A comparison was made between the magnitude of the TPF1 peak, which is the peak acceleration of TPF1, and the magnitudes of the TPF2 peak, TPF3 peak, and TPF4 peak, which are the peak accelerations of TPF2, TPF3, and TPF3, respectively. At this time, the other peaks among the TPF2 peak, the TPF3 peak, and the TPF4 peak, which are harmonic frequencies of the TPF1, have similar values as compared with the magnitude of the TPF1 peak. In the machining performed in this state, the machining vibration sound increases, and as to the frequency of the machining sound, the sounds of TPF2, TPF3, and TPF4 are mixed in addition to the sound of TPF1, and at the same time, the sound of a low frequency other than the excited TPF frequency is also mixed. Therefore, the machining sound sounds like a noisy machining sound with a high volume level of vibration and does not have a feeling of easy machinability, and further, the machined surface becomes rough.

As described above, in the machine state monitoring system 10, in order to determine whether the machine state is good, the peak acceleration of the Tool Passing Frequency (TPF) and the peak acceleration of the harmonic frequency in machining are always monitored, and the change in the vibration amount of TPF2 to TPFn (n is an integer of 3 or more) is compared with the vibration amount of the peak of TPF 1. Hereinafter, details will be described.

As shown in fig. 1, the machining vibrations picked up by the acceleration sensor 26 and/or the microphone 28 are sent to the arithmetic unit 38 by means of the amplifier and filter circuit 36. As shown in fig. 2, in the arithmetic unit 38, the machining vibration is subjected to an arithmetic analysis of fourier transform (fourier series expansion), and its value is displayed on the spectrum display section 52, and the display is updated every fixed time (generally, every second). Meanwhile, in the input setting unit 40, information including the number of revolutions of the spindle 18, the number of blades of the tool 22, the number of natural vibrations, and the like is input. From this input information, spectral vibration information can be distinguished between TPF1, TPF2, TPF3.. TPFn, etc., respectively.

As shown in fig. 3, when the vibration intensity (peak acceleration) displayed on the spectrum display unit 52 exceeds the threshold set by the type of frequency, the vibration intensity is transmitted to the type display window of the threshold excess accumulation sum display unit 56 as the accumulated value exceeding the threshold. Alternatively, it is also possible to accumulate and display the accumulated value in the type display window of the threshold excess accumulation and display portion 56 when an accumulation signal indicating the excess of the threshold of the TPF1 is issued a plurality of times, for example, by the separately provided repetition counter 42, before the accumulated value detected in the spectrum display portion 52 is accumulated and displayed in the type display window of the threshold excess accumulation and display portion 56. The mounting of the count of the repetition counter in this case is performed on the setting screen of the input setting unit 40.

In the threshold-exceeding totalization display unit 56, for example, when the frequency spectrum of the vibration of TPF1 (TPF1 peak value) generated at the time of machining by the tool 22 exceeds the threshold set in the frequency spectrum display unit 52, the totalized value exceeding the threshold is transmitted to the first display column 56a of the threshold-exceeding totalization display unit 56. In the first display field 56a, the accumulated value of TPF1 is accumulatively displayed. Therefore, every time the integrated value exceeding the threshold value of TPF1 is transmitted, the graphs displayed in the first display column 56a of the threshold-value-exceeding integrated sum display unit 56 are subjected to integrated addition.

Similarly, when the vibration of TPF2 of the harmonic frequency (TPF2 peak value) exceeds the threshold value set in the frequency spectrum display section 52 at the frequency spectrum of the machining vibration, the integrated value exceeding the threshold value is transmitted to the second display column 56b of the threshold value excess integration and display section 56. In the second display field 56b, the accumulated value of TPF2 is accumulatively displayed. Therefore, every time the integrated value exceeding the threshold value of TPF2 is transmitted, the graphs displayed in the second display column 56b of the threshold-value-exceeding integrated sum display unit 56 are subjected to integrated addition.

Further, when the vibration of the TPF3 at the harmonic frequency (TPF3 peak value) exceeds the threshold value set in the spectrum display unit 52, the integrated value exceeding the threshold value is transmitted to the third display column 56c of the threshold-value-exceeding integrated sum display unit 56. Meanwhile, when the vibration of the TPF4 at the harmonic frequency (TPF4 peak value) exceeds the threshold value set in the spectrum display unit 52, the integrated value exceeding the threshold value is transmitted to the fourth display column 56d of the threshold-value-exceeding integrated sum display unit 56. Further, when the vibrations of the harmonic frequencies of the TPFs other than the TPFs 1 to 4 exceed the threshold value set in the spectrum display section 52, the integrated value exceeding the threshold value is displayed collectively in the fifth display column 56e of the threshold-value-exceeding integration display section 56.

The change display unit 58 compares the cumulative integrated values in the first to fourth display fields 56a to 56d (including the fifth display field 56e as necessary) of the cumulative display unit 56, and displays the cumulative integrated values in which the threshold value exceeds the threshold value of the data of the spectrum display unit 52. At this time, the comparison parameter may be selected by a separate setting screen. Specifically, in the change display section 58, the cumulative integrated value of TPF1 (the number of times of exceeding the TPF threshold) is compared with the value of the sum of the cumulative integrated values (the number of times of exceeding the harmonic TPF threshold) of TPF2, TPF3, and TPF4 (further, TPFn as necessary). That is, "(the integrated value of TPF2 + the integrated value of TPF3 + the integrated value of TPF4 + the integrated value of TPFn)/the integrated value of TPF 1" is equal to the comparison value.

The change display unit 58 shown in fig. 8 displays a case where the cumulative value of the sum of the cumulative values of TPF2, TPF3, and TPF4 (TPFn, if necessary) is lower than the cumulative value of TPF 1. The comparison value thereof is 1 or less, and the fact that the machining state is a free-cutting state is detected. Meanwhile, the change display unit 58 shown in fig. 9 displays a case where the cumulative value of the sum of the cumulative values of TPF2, TPF3, and TPF4 (further, TPFn as necessary) is higher than the cumulative value of TPF 1. The comparison value thereof was 2.5 or more, and the fact that the machining state was a non-free cutting state was examined.

That is, from the frequency spectrum of the machining vibration, by extracting a significant specific signal indicating the exceeding of the threshold at the tool passing frequency and its harmonic frequency and comparing the occurrence of the specific signal, it is possible to show whether the machining is good or not by numerical values and graphs. The arbitrary selection threshold exceeds an arbitrary accumulation value of the type display window of the accumulation and display section 56 for comparison.

In this case, in the present embodiment, when machining is performed on the workpiece W by the tool 22, the correlation between the number of peaks occurring at the tool passing frequency (TPF1) and the number of peaks occurring at the harmonic frequency (TPF2 —) can be seen. In a good machining state, the number of peaks occurring at the tool pass frequency is significant, whereas in a poor machining state, the number of peaks occurring at the harmonic frequency increases along with the tool pass frequency. Therefore, from the change in the relationship between the two, an effect is obtained in which the determination of whether the machining state is good or not can be efficiently performed with high accuracy.

In the change display section 58, a threshold value for determining a change in the ratio between the number of peaks occurring at the tool passing frequency (TPF1) and the sum of the number of peaks occurring at a plurality of harmonic frequencies (TPF2 —) is set, and a determination signal of the compared state is output. For example, in the case where the comparison value is 1 or less, an OK signal indicating the free-cutting property (good machining state) is output. Further, in the case where the comparison value exceeds 1, the output signal is a + OK signal indicating that the state is the predicted state, and in the case where the comparison value exceeds 2.5, an NG signal in a non-free cutting state (poor machining state) is output.

Also, by monitoring the relationship between the vibration at TPF1 included in the frequency spectrum of machining vibrations and the vibration at a harmonic frequency (TPF2 —), the determination of the machining state is performed efficiently over time. In addition, when automatic machining is performed, whether or not free-cutting machining is performed can be automatically determined by monitoring the comparison value.

In the case where the accumulated comparison value displayed on the change display portion 58 is related to wear of the blade of the tool, the output of the comparison value signal may be used as a signal for tool replacement. For example, in the case where a working edge having an acute angle is sharp, the change in the cumulative comparison value is small. However, as the machining proceeds and the wear of the cutting edge progresses, the change in the cumulative comparison value increases. Therefore, by using the accumulated comparison value for determining the replacement time of the blade, effective replacement of the blade can be performed.

Further, in the case where the load of machining varies during machining, for example, when chipping occurs in the edge during machining, there is a tendency that the number of peaks occurring at the harmonic frequency (TPF2 —) increases as compared with the number of peaks occurring at the tool passing frequency without greatly changing the machining allowance or the like of the workpiece W. Therefore, the cumulative comparison value displayed on the change display portion 58 can be used as a function of monitoring the machining state.

Fig. 4 and 6 show the difference between the vibration states of machining (cutting) due to the difference in the number of revolutions. However, in the case of searching for the optimum number of revolutions while changing the number of revolutions for cutting, the difference may be used as a means of determining which number of revolutions indicates the free-cutting property. Specifically, it can be used to determine that the number of revolutions at which the comparison value becomes small is a good machining condition.

Industrial applicability

List of reference numerals

10: processing state monitoring system

12: machine tool

14: shell body

18: mandrel

20: tool rack

22: cutting tool

26: acceleration sensor

28: microphone (CN)

30: controller

32: mechanical control panel

34: control operation panel

38: arithmetic unit

40: input setting unit

44: machining state determination unit

46: input/output unit

48: display unit

52: frequency spectrum display part

56: threshold value excess accumulation sum display part

56a to 56 e: display bar

58: change display unit

Claims

1. A vibration monitoring method for a working machine, in which machining vibrations detected at the time of machining are expanded in a frequency spectrum including frequency and acceleration by fourier series expansion, the vibration monitoring method comprising the steps of:

comparing a tool passing frequency peak value serving as a peak acceleration at a tool passing frequency calculated from the number of revolutions and the number of blades of the machining tool with a tool passing frequency threshold value serving as a peak threshold value of the tool passing frequency preset for a frequency spectrum, and displaying the number of times the tool passing frequency peak value exceeds the tool passing frequency threshold value on a tool passing frequency threshold value exceeding integrating and displaying part;

comparing a harmonic tool pass frequency peak value serving as a peak acceleration at a harmonic frequency that is an integral multiple of the tool pass frequency with a harmonic tool pass frequency threshold value serving as a peak threshold value of the harmonic frequency preset for the frequency spectrum, and displaying the number of times the harmonic tool pass frequency peak value exceeds the harmonic tool pass frequency threshold value on a harmonic tool pass frequency threshold value exceeding accumulation and display section; and

the number of times the tool pass frequency threshold is exceeded is compared with the number of times the harmonic tool pass frequency threshold is exceeded and displayed on a change display.

2. The vibration monitoring method for a work machine according to claim 1, wherein the harmonic tool passing frequency threshold exceeding integrating and displaying section has at least:

a first harmonic tool pass frequency threshold exceed accumulation and display showing a number of times a first harmonic tool pass frequency peak exceeds the harmonic tool pass frequency threshold at a harmonic frequency twice the tool pass frequency; and

a second harmonic tool pass frequency threshold excess accumulation and display showing the number of times a second harmonic tool pass frequency peak exceeds the harmonic tool pass frequency threshold at a harmonic frequency three times the tool pass frequency; and is

The change display unit compares and displays the sum of at least the number of times that the first harmonic tool passing frequency threshold is exceeded and the number of times that the second harmonic tool passing frequency threshold is exceeded with the number of times that the tool passing frequency threshold is exceeded.

3. A vibration monitoring system for a working machine in which machining vibrations detected at machining are expanded in a frequency spectrum including frequency and acceleration by fourier series expansion, the vibration monitoring system comprising:

a tool passing frequency threshold exceeding accumulation and display section that compares a tool passing frequency peak serving as a peak acceleration at a tool passing frequency calculated from the number of revolutions and the number of blades of the machining tool with a tool passing frequency threshold serving as a peak threshold of the tool passing frequency preset for the frequency spectrum, and displays the number of times the tool passing frequency peak exceeds the tool passing frequency threshold;

a harmonic tool passing frequency threshold value exceeding accumulation and display section that compares a harmonic tool passing frequency peak value serving as a peak acceleration at a harmonic frequency that is an integral multiple of the tool passing frequency with a harmonic tool passing frequency threshold value serving as a peak threshold value of the harmonic frequency preset for the frequency spectrum, and displays the number of times the harmonic tool passing frequency peak value exceeds the harmonic tool passing frequency threshold value; and

a change display part comparing and displaying the number of times of exceeding the tool passing frequency threshold with the number of times of exceeding the harmonic tool passing frequency threshold.

4. A vibration monitoring system for a work machine as defined in claim 3, wherein the harmonic tool pass frequency threshold exceeding accumulation and display comprises at least: