KR101867136B1 - Method of tool wear and breakage detection for material cutting operations - Google Patents

Method of tool wear and breakage detection for material cutting operations Download PDF

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Publication number
KR101867136B1
KR101867136B1 KR1020150172943A KR20150172943A KR101867136B1 KR 101867136 B1 KR101867136 B1 KR 101867136B1 KR 1020150172943 A KR1020150172943 A KR 1020150172943A KR 20150172943 A KR20150172943 A KR 20150172943A KR 101867136 B1 KR101867136 B1 KR 101867136B1
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South Korea
Prior art keywords
vibration
tool
value
sampling
current
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KR1020150172943A
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Korean (ko)
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KR20170066818A (en
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오영교
메르니쳐 알렉스
윤여찬
방태형
저커맨 마크
패인스테인 보리스
타바흐니 에드워드
라비노비치 시몬
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현대위아 주식회사
오마트 엘티디.
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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
    • 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
    • B23Q17/0957—Detection of tool breakage
    • 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
    • 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
    • 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
    • B23Q2717/00—Arrangements for indicating or measuring

Abstract

The present invention relates to a method of detecting wear and tear of a tool, and more particularly, to a method and apparatus for cutting a tool capable of accurately detecting wear and tear of a tool in real time by analyzing a frequency spectrum frequency component of a rotating tool for cutting operation And a method of detecting wear and tear of a tool.

Description

TECHNICAL FIELD [0001] The present invention relates to a method for detecting wear and breakage of a tool for a cutting operation,

The present invention relates to a method of detecting wear and tear of a tool, and more particularly, to a method and apparatus for cutting a tool capable of accurately detecting wear and tear of a tool in real time by analyzing a frequency spectrum frequency component of a rotating tool for cutting operation And a method of detecting wear and tear of a tool.

Generally, in a machine tool in which a workpiece is cut by mounting a tool on a main shaft, the tool is gradually worn out due to the cutting resistance between the tool and the workpiece, and the tool is broken due to various causes during the machining process.

Wear and breakage of such a tool causes defective machining of the workpiece.

On the other hand, the determination of the machining failure is made in the final inspection stage after the machining is finished. Since the machining stagnant on the production line is judged as a machining defective until the final inspection is performed after the defect, the productivity is lowered.

In addition, the downtime of the machine tool due to the replacement of abrasive or damaged tools increases, which also contributes to the decline in productivity.

Accordingly, there is a need to develop a method of detecting wear and tear of a tool that can accurately detect wear and breakage of the tool during cutting operation to improve productivity and improve machining accuracy and roughness of the workpiece.

It is an object of the present invention to provide a method of detecting wear and tear of a tool capable of improving productivity and machining accuracy of a tool by detecting wear and tear of a tool in real time during a cutting operation, Method.

The objects of the present invention are not limited to the above-mentioned objects, and other objects not mentioned can be clearly understood by those skilled in the art from the following description.

According to another aspect of the present invention, there is provided a method of detecting abrasion of a tool for a cutting operation, the method comprising: detecting vibration of a tool at a predetermined sampling period during a cutting operation to calculate a vibration amount; And a step of calculating a change in vibration amount between a previous sampling time and a current sampling time and detecting that wear has occurred when the vibration amount change is larger than a predetermined reference change amount .

In a preferred embodiment, the step of calculating the amount of vibration comprises: calculating blade harmonic frequencies according to the number of blades; The cutting operation is started and the vibration of the tool is detected; And a step of calculating an effective amplitude value of each blade harmonic frequency by Fourier transforming the detected vibration signal, and calculating a vibration amount by multiplying the calculated effective amplitude values.

In a preferred embodiment, the cutting operation is performed in a predetermined cycle, and the vibration of the tool is detected at a predetermined sampling frequency for one cycle, and the calculation of the vibration amount is performed for each sampling, Calculating a total amount of vibration of the previous cycle and a current cycle after the calculation of the total amount of vibration, and calculating the total amount of vibration change Minute is greater than a predetermined reference change, wear is detected.

In a preferred embodiment, the effective amplitude value is calculated as an average effective amplitude value of a lower harmonic frequency, an upper frequency obtained by adding a predetermined frequency to a corresponding blade harmonic frequency, and a lower frequency obtained by subtracting a predetermined frequency from the harmonic frequency.

In a preferred embodiment, the blend harmonic frequency is calculated by the following equation (1).

[Equation 1]

Figure 112015119290541-pat00001

Here, f H (i) is the blade harmonic frequency, RPM is the number of revolutions per minute of the tool, flutes is the number of blades of the tool, and i is each degree (1, ..., n) of the blade harmonic frequency.

In a preferred embodiment, the vibration amount is calculated by the following equation (2).

&Quot; (2) "

Figure 112015119290541-pat00002

Where A v is the vibration amount, FFT (f H (i) ) is the amplitude of the i-th order blend harmonic frequency, and n is the highest order of the blend harmonic frequencies.

In a preferred embodiment, the total vibration amount is calculated by the following equation (3).

&Quot; (3) "

Figure 112015119290541-pat00003

Here, Q v is the total amount of vibration, N is the number of samples per one cycle, A v (k) is a vibration amount in the k-th sampling.

In a preferred embodiment, the amount of change in the total amount of vibration is calculated by the following equation (4).

&Quot; (4) "

Figure 112015119290541-pat00004

Here, m is the amount of change in the total amount of vibration, C (K) is the current cycle number, and Qv (K) is the total vibration amount of the current cycle.

The present invention further provides a computer program in a computer readable medium for performing a wear detection method of the tool in combination with a computer.

In the present invention, two workpieces of the same specification are subjected to a cutting operation using a normal tool, the vibration of a tool generated during the cutting operation is measured at a predetermined sampling period, and the change amount of vibration amount between two cutting operations &Quot; learning vibration amount change value ") for each sampling and storing it as a learning data array; And the actual workpiece is subjected to a cutting operation using the current tool, the vibration of the tool is measured at a predetermined sampling period during the cutting operation, and the vibration amount change value (hereinafter, ), And when the ratio of the learning vibration amount change value of sampling corresponding to the current sampling out of the current vibration amount change value and the learning vibration amount change values of the learning data array is a predetermined threshold ratio or more, And determining that the breakage of the tool is broken.

In a preferred embodiment of the present invention, the step of storing the learning data array comprises: a step of storing a predetermined workpiece (hereinafter referred to as a "first workpiece") while performing a cutting operation with a normal tool Measuring a vibration of the first normal tool at every cycle and acquiring an amplitude effective value corresponding to the rotational harmonic frequencies of the first normal tool as a data array (hereinafter referred to as a 'first data array') for each sampling; (Hereinafter, referred to as a "second workpiece") having the same specifications as those of the first workpiece is cut with a normal tool having the same specifications as the first normal tool (hereinafter referred to as a "second normal tool" Measuring vibration of the second normal tool and obtaining an amplitude effective value corresponding to the rotational harmonic frequencies of the second normal tool for each sampling as a data array (hereinafter referred to as a 'second data array'); And a difference value between the first data array and the second data array for each sampling to calculate an amplitude variation value for each sampling and storing the variation value as the learning data array as the learning vibration variation value; .

In a preferred embodiment of the present invention, the step of determining the breakage of the current tool includes: starting an actual cutting operation with the current tool, measuring a vibration of the current tool at a predetermined sampling period, Obtaining an amplitude effective value (hereinafter referred to as 'initial amplitude effective value') corresponding to the harmonic frequencies; (Hereinafter referred to as 'current amplitude effective value') corresponding to the rotation harmonic frequencies, and adding the difference between the initial amplitude effective value and the current amplitude effective value to calculate the current vibration amount change Calculating a value; And calculating a ratio of the learning vibration amount change value of sampling corresponding to the current sampling out of the current vibration amount change value and the learning vibration amount change values of the learning data array, and, when the calculated ratio is equal to or greater than a predetermined threshold ratio, And determining that the tool is broken.

The present invention further provides a computer program stored in a computer-readable medium for performing a method of detecting breakage of the tool in combination with a computer.

The present invention has the following excellent effects.

According to the method for detecting wear and tear of a tool of the present invention, there is an advantage that wear and breakage can be precisely performed in real time using a change in frequency component of a vibration spectrum of a tool.

1 illustrates a wear and tear detection system for performing a wear and tear detection method of a tool according to an embodiment of the present invention;
2 is a flow chart of a tool wear detection method according to an embodiment of the present invention,
3 is a view for explaining a blade harmonic frequency of a tool wear detection method according to an embodiment of the present invention;
4 is a view for explaining a method of determining wear of a tool in a tool wear detection method according to an embodiment of the present invention;
5 is a flowchart of a method of detecting breakage of a tool according to an embodiment of the present invention.

Although the terms used in the present invention have been selected as general terms that are widely used at present, there are some terms selected arbitrarily by the applicant in a specific case. In this case, the meaning described or used in the detailed description part of the invention The meaning must be grasped.

Hereinafter, the technical structure of the present invention will be described in detail with reference to preferred embodiments shown in the accompanying drawings.

However, the present invention is not limited to the embodiments described herein but may be embodied in other forms. Like reference numerals designate like elements throughout the specification.

FIG. 1 is a schematic view of a wear and tear detection system for performing a wear and tear detection method of a tool according to an embodiment of the present invention. Referring to FIG.

Referring to FIG. 1, a wear and tear detection system 100 for performing a wear and tear detection method of a tool according to an embodiment of the present invention includes a vibration sensor 110, a data collection device 120, 130).

The vibration sensor 110 is attached to the main shaft of the machine tool 10 to detect vibration of the tool.

The vibration sensor 110 may be an acceleration sensor or a gyro sensor.

The data acquisition device 120 DAQ receives a vibration signal from the vibration sensor 110 and performs a fast Fourier transform (FFT) on the vibration signal in real time.

The arithmetic unit 130 receives the fast Fourier transformed vibration data from the data collection unit 120 and performs the wear and break detection method of the present invention through a predetermined wear detection algorithm and a damage detection algorithm.

The computing device 130 is an optical computing device capable of performing functions of a computer such as a general personal computer as well as an embedded device that is specially manufactured for the present invention and can be mounted on the machine tool 10.

In addition, the computing device 130 stores a computer program for performing the wear detection algorithm and the damage detection algorithm.

In addition, the computer program may be recorded on a computer-readable recording medium and provided separately. The recording medium may be one designed or configured specifically for the present invention, It may be possible.

Examples of the optical recording medium include a magnetic medium such as a hard disk, a floppy disk and a magnetic tape, an optical recording medium such as a CD and a DVD, a magnetic-optical recording medium capable of combining magnetic and optical recording, a ROM, Lt; RTI ID = 0.0 > and / or < / RTI >

In addition, the computer program may be a program consisting of program commands, local data files, local data structures, etc., alone or in combination, and may be executed by a computer using an interpreter or the like as well as machine code Lt; RTI ID = 0.0 > language code. ≪ / RTI >

Hereinafter, a method of detecting wear of a tool according to an embodiment of the present invention will be described in detail with reference to FIG.

Referring to FIG. 2, a tool wear detection method according to an embodiment of the present invention includes a step of calculating a vibration amount of a tool (S1000) and a step of detecting occurrence of wear based on the calculated vibration amount (S2000 ).

The step of calculating the amount of vibration (S1000) is a step of calculating the amount of vibration by detecting the vibration of the tool at a predetermined sampling period during the cutting operation.

First, before starting the cutting operation, the blade harmonic frequency is calculated (S1100).

In the present invention, as shown in FIG. 3, the blade frequency of 1 to 5 times (order) is referred to as a blade harmonic frequency Respectively.

However, all the harmonic frequencies of the blade frequency may be set to the blade harmonic frequency.

However, it is preferable to set the blade harmonic frequency to frequencies corresponding to 1 to 5 times of the blade frequency in order to quickly detect wear using only meaningful vibration information.

In addition, the blade harmonic frequency can be calculated using the following equation (1).

[Equation 1]

Figure 112015119290541-pat00005

(I) is the blade harmonic frequency, RPM is the number of revolutions per minute of the tool, flutes is the number of blades of the tool, and i is a multiple (1, ..., n) of the blend harmonic frequency

Also, the value obtained by dividing the number of revolutions per minute of the tool by 60 is the tool rotation frequency of the tool, and the value obtained by multiplying the number of the blade of the rotation frequency of the tool is the blade frequency.

Next, the cutting operation is started (S1200), and the vibration sensor 110 detects the vibration of the tool (S1300).

Further, the vibration sensor 110 detects vibration of the tool at a predetermined sampling period.

Next, the data acquisition device 120 acquires a vibration signal detected by the vibration sensor 110 and performs a fast Fourier transform (S1400), and then transmits information about a frequency component to the calculation device 130 .

Next, the computing device 130 calculates an effective amplitude value (RMS) of each blade harmonic frequency (S1500), and calculates a vibration amount by multiplying all of the calculated effective amplitude values (S1600).

Further, the vibration amount is calculated using the following equation (2).

&Quot; (2) "

Figure 112015119290541-pat00006

Here, A v is the vibration amount, FFT (f H (i)) is the amplitude (frequency components), n of knife conditioner frequency of i order is the highest order (embodiment clerical script of the invention of the blade conditioning frequency is "5" )to be.

Also, referring to Equation 2, the embodiment of the present invention, (f H (i)) the rms amplitude value corresponding blade conditioner frequency, the upper frequency (f H (i, plus the '1' to the blade harmonic frequency ) + 1) and the average effective amplitude value of the lower frequency (f H (i) -1) obtained by subtracting '1' from the harmonic frequency of the blade is calculated to minimize the calculation error of the effective amplitude value.

In addition, the frequency value '1' to be added or subtracted for the calculation of the upper frequency and the lower frequency can be changed to a different value depending on the designer.

Further, the vibration amount is calculated for each sampling for detecting the vibration.

Further, the cutting operation is performed in a predetermined cycle, and vibration is detected at a predetermined sampling frequency within one cycle.

That is, a plurality of vibration amounts are calculated during a cutting operation of one cycle.

Next, the vibration amounts are averaged to calculate the total vibration amount as a vibration amount for one cycle (S1700).

Further, the total vibration amount is calculated by the following equation (3).

&Quot; (3) "

Figure 112015119290541-pat00007

Here, Q v is the total amount of vibration, N is the number of samples per one cycle, A v (k) is a vibration amount in the k-th sampling.

Next, whether abrasion has occurred or not is detected based on the calculated total vibration amount (S2000).

Further, the occurrence of wear is detected by calculating the degree of change in the total vibration amount.

In the present invention, when the total amount of vibration in the current cycle and the amount of change in total amount of vibration in the previous cycle are greater than a predetermined reference change (S2100), it is determined that wear has occurred (S2200) .

Further, the vibration total change minute vibration amount of the current cycle (C (k)) vibration total amount (Q v (k)) and the previous cycle (C (k-1)) as shown in Fig. 4 (Q v (k-1) ).

&Quot; (4) "

Figure 112015119290541-pat00008

Here, m is the amount of change in the total amount of vibration, C (K) is the current cycle number, and Qv (K) is the total vibration amount of the current cycle.

However, the detection of the occurrence of abrasion can be judged by using the change of the vibration amount calculated at each sampling time, not by the change of the vibration total amount.

Hereinafter, a method of detecting breakage of a tool according to an embodiment of the present invention will be described in detail with reference to FIG.

In addition, the breakage detection method of the tool may be performed in parallel with the above-described abrasion detection method, and may be performed at the same time.

In addition, the tool damage detection method includes a learning mode (S3000) and a damage detection mode (S4000).

In the learning mode (S3000), two workpieces having the same specifications are subjected to a cutting operation using a normal tool having the same specifications, the vibration of the tool generated during the cutting operation is measured at a predetermined sampling period, (Hereinafter referred to as " learning vibration amount change value ") for each sampling and storing it as a learning data array.

That is, the learning mode (S3000) is a process of acquiring a vibration amount change value as a reference for comparison.

More specifically, the learning mode (S3000) first processes the first workpiece into a first normal tool (S3100).

Next, the vibration of the first normal tool is measured at a predetermined sampling period, and the amplitude effective value of the vibration spectra frequency component of the first normal tool is calculated for each sampling to acquire the first data array (S3200).

In addition, the rotational harmonic frequency is a harmonic frequency of the rotational frequency obtained by dividing the rotational speed per minute of the tool by 60.

In addition, the rotational harmonic frequency is a total rotational harmonic frequency having a rotational frequency within a predetermined degree range as compared with the blade harmonic frequency shown in Equation (1).

However, only the components of the rotation harmonic waves within the meaningful order range can be calculated as the amplitude rms value to obtain the first data array.

In addition, the first data array can be expressed by Equation (5) below.

&Quot; (5) "

Figure 112015119290541-pat00009

Where a l 1n is the amplitude effective value, l is a number corresponding to the order of the rotational frequency as a number of vibration spectrum frequency components that is a multiple of the rotational frequency, 1 is a number for identification of the first data array, n Is the sampling number.

Next, the second workpiece is processed into the second normal tool (S3300).

Further, during the machining of the second normal tool, the vibration is detected at a predetermined sampling period and the second data arrangement is obtained (S3400)

The second data array is the same as the first data array acquiring process, and is a set corresponding to the first data array, so a detailed description will be omitted.

In addition, the second data array can be expressed by Equation (6) below.

&Quot; (6) "

Figure 112015119290541-pat00010

Next, a difference value between the first data array and the second data array, that is, a change in amplitude of each rotation harmonic frequency component, that is, a change amount of vibration amount (hereinafter, referred to as a learning vibration amount change value) (S3500).

Further, the learning vibration amount change value is calculated using the following equation (7).

&Quot; (7) "

Figure 112015119290541-pat00011

Here, n is the number of samples, l is the number of vibration spectrum frequency components, which is a multiple of the rotation frequency, corresponding to the order of the rotation frequency, and L is an indication that the learned vibration amount change value.

That is, the learning vibration amount change value is calculated by adding the difference between the sampled time and the amplitude effective values of the vibration spectrum frequency among the values of the first data array and the second data array.

Also, the learning vibration amount change value is calculated for each sampling as shown in Equation (8) below and stored as one learning data array.

&Quot; (8) "

Figure 112015119290541-pat00012

Up to this point, the learning mode (S3000) is performed. After the learning mode is ended, a breakage detection mode (S4000) for detecting breakage of the tool during actual cutting is started.

In the breakage detection mode S4000, the actual workpiece is subjected to a cutting operation using the current tool, the vibration of the tool is measured at a predetermined sampling period during the cutting operation, the variation value of the vibration amount between the initial sampling and the current sampling is calculated And comparing the learning vibration amount change value of the learning data array with the learning vibration amount change value of the sampling corresponding to the current sampling to determine whether the current tool is broken.

More specifically, first, the actual workpiece is started to be machined with the current tool (S4100).

Next, the vibration of the current tool is sensed at a predetermined sampling period, and the amplitude effective value corresponding to the rotational harmonic frequencies of the current tool is calculated and stored (S4200, S4300).

In FIG. 5, for convenience of explanation, the process of calculating the amplitude effective value at the initial sampling time (S4200) and the process of calculating the amplitude effective value at the current sampling time (S4200) are shown separately. However, Respectively.

In addition, the amplitude rms value of the current tool is calculated in a manner similar to the amplitude rms value described in Equation (5).

That is, the amplitude rms values of the current tool are calculated for each sampling.

Also, at the initial sampling, the amplitude rms value for the sensed vibration is defined as the initial amplitude rms value, and the amplitude rms value for the vibration sensed at the current sampling is defined as the current amplitude rms value.

Next, the initial effective value change value of the sampling and the current sampling time is calculated to acquire a change amount of vibration amount (hereinafter referred to as 'current vibration amount change value') (S4400).

Also, the current vibration amount change value can be calculated by Equation (9) below.

&Quot; (9) "

Figure 112015119290541-pat00013

Here, n is the number of samples, l is the number of vibration spectrum frequency components, which is a multiple of the rotation frequency, corresponding to the order of the rotation frequency, and T is an indication that the vibration amount is the current change amount.

That is, the current vibration amount change value is calculated for each sampling and is calculated in a form similar to the learning vibration amount change value described in Equation (7).

Next, the current vibration amount change value and the learning vibration amount change value are compared with each other (S4500), and whether or not the tool is broken is detected (S4600).

Also, the current vibration amount change value and the learning vibration amount change value to be compared are values calculated at the same sampling time.

In the present invention, when the ratio between the current vibration amount change value and the learning vibration amount change value is equal to or greater than the threshold ratio (S4500), it is detected that the current tool is broken, and the current vibration amount change It is possible to determine that the current tool is broken if the value obtained by dividing the learning vibration amount change value by the value is equal to or greater than a predetermined threshold ratio.

&Quot; (10) "

Figure 112015119290541-pat00014

In addition, the threshold ratio can be appropriately selected and set by a designer as an empiric coefficient based on empirical rules.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, Various changes and modifications will be possible.

100: abrasion and breakage detection system 100: vibration sensor
120: data collecting device 130: calculating device

Claims (17)

A wear detection method for detecting wear of a tool for a cutting operation; And a damage detection method that is performed in parallel with the wear detection method and detects breakage of a tool,
The wear detection method:
Calculating a vibration amount by detecting vibration of the tool at a predetermined sampling period during a cutting operation; And
Calculating a change in vibration amount between a previous sampling time and a current sampling time and detecting that wear has occurred when the change in vibration amount is greater than a predetermined reference change,
Calculating the amount of vibration comprises:
Calculating blade harmonic frequencies according to the number of blades;
The cutting operation is started and the vibration of the tool is detected; And
Calculating an effective amplitude value of each blade harmonic frequency by Fourier transforming the detected vibration signal, and calculating a vibration amount by multiplying the calculated effective amplitude values,
Wherein the cutting operation is performed in a predetermined cycle, the vibration of the tool is detected at a predetermined sampling frequency for one cycle, the calculation of the vibration amount is performed for each sampling,
Calculating the total amount of vibration by averaging the amount of vibration during each cycle after the step of calculating the amount of vibration,
Calculating a change in the total amount of vibration of the previous cycle and a current cycle after the calculation of the total amount of vibration and detecting that wear has occurred when the change in the total amount of vibration is greater than a predetermined reference change,
The breakage detection method according to claim 1,
Two workpieces of the same specifications are subjected to cutting work using a normal tool, the vibrations of the tool generated during the cutting operation are measured at a predetermined sampling period, and the vibration amount change value between two cutting operations Value ') for each sampling and storing it as a learning data array; And
The vibration of the tool is measured at a predetermined sampling period during the cutting operation, and the vibration amount change value (hereinafter, referred to as the 'current vibration amount change value') of the initial sampling and the current sampling is calculated, If the ratio of the learning vibration amount change value of the sampling corresponding to the current sampling among the current vibration amount change value and the learning vibration amount change values of the learning data array is equal to or greater than a predetermined threshold ratio, And determining that the tool is damaged if it is determined that the tool is damaged.
delete delete The method according to claim 1,
Wherein the effective amplitude value is calculated as an average effective amplitude value of a lower harmonic frequency, an upper frequency obtained by adding a predetermined frequency to a corresponding blend harmonic frequency, and a lower frequency obtained by subtracting a predetermined frequency from the harmonic frequency. Breakage detection method.
5. The method of claim 4,
Wherein the blade harmonic frequency is calculated by the following equation (1).
[Equation 1]
Figure 112018044306112-pat00015

Where f H (i) is the blade harmonic frequency, RPM is the tool revolution per minute, flutes is the blade number of the tool, and i is the order (1, ..., n) of the blade harmonic frequency.
5. The method of claim 4,
Wherein the vibration amount is calculated by the following equation (2).
&Quot; (2) "
Figure 112018044306112-pat00016

Where A v is the vibration amount, FFT (f H (i) ) is the amplitude of the i-th order blend harmonic frequency, and n is the highest order of the blend harmonic frequencies.
The method according to claim 6,
Wherein the total amount of vibration is calculated by the following equation (3).
&Quot; (3) "
Figure 112018044306112-pat00017

Here, Q v is the total amount of vibration, N is the number of samples per one cycle, A v (k) is a vibration amount in the k-th sampling.
delete A computer program for wear and tear detection of a tool stored in a computer-readable medium for executing the method of any one of claims 1 to 7 in combination with a computer.
delete delete delete delete delete The method according to claim 1,
Storing the learning data array,
The vibration of the first normal tool is measured at a predetermined sampling period during a cutting operation of a predetermined workpiece (hereinafter referred to as a 'first workpiece') with a normal tool (hereinafter referred to as a 'first normal tool'), Obtaining an amplitude effective value corresponding to rotation harmonics frequencies of one normal tool in a data array (hereinafter referred to as a 'first data array');
(Hereinafter, referred to as a "second workpiece") having the same specifications as those of the first workpiece is cut with a normal tool having the same specifications as the first normal tool (hereinafter referred to as a "second normal tool" Measuring vibration of the second normal tool and obtaining an amplitude effective value corresponding to the rotational harmonic frequencies of the second normal tool for each sampling as a data array (hereinafter referred to as a 'second data array'); And
Adding a difference value between the first data array and the second data array for each sampling to calculate an amplitude variation value for each sampling and storing the variation value as the learning data array as the learning vibration variation value; Wherein the method comprises the steps of:
16. The method of claim 15,
Determining a breakage of the current tool,
The actual cutting operation is started with the current tool and the vibration of the current tool is measured at a predetermined sampling period and an amplitude effective value (hereinafter referred to as 'initial amplitude effective value') corresponding to the rotational harmonic frequencies of the current tool Obtaining;
(Hereinafter referred to as 'current amplitude effective value') corresponding to the rotation harmonic frequencies, and adding the difference between the initial amplitude effective value and the current amplitude effective value to calculate the current vibration amount change Calculating a value; And
Calculating a ratio of the learning vibration amount change value of the sampling corresponding to the current sampling out of the current vibration amount change value and the learning vibration amount change values of the learning data array and if the calculated ratio is equal to or greater than a predetermined threshold ratio, And determining that the tool is damaged.



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