JP7379064B2 - cutting equipment - Google Patents

Description

The present invention relates to a cutting device for cutting a workpiece.

A cutting device that uses a cutting blade to cut a workpiece held on a chuck table cuts the workpiece by bringing the cutting blade into contact with the workpiece while supplying cutting water to the cutting blade. During cutting, the cutting blade may vibrate more than normal due to clogging, crushing, chipping, etc., or due to wrong setting of the cutting feed rate, causing chipping on the surface of the workpiece. there's a possibility that.

Therefore, in order to detect the chipping that has occurred, as disclosed in Patent Document 1 and Patent Document 2, the vibration of the cutting blade is detected by an AE sensor during the cutting process, and the magnitude of the vibration of the cutting blade (AE There is a method of determining that chipping has occurred in the workpiece when the value (value) exceeds a threshold value.

Japanese Patent Application Publication No. 2015-170745 Japanese Patent Application Publication No. 2018-117092

However, the above-mentioned cutting blade is worn out by cutting. The magnitude of the elastic wave signal (AE value) detected by the AE sensor changes depending on the amount of wear on the cutting blade, and the amount and rate of change differ depending on the frequency band. Therefore, even though there is no processing abnormality such as load applied to the cutting blade and large vibrations occurring during cutting, the AE value increases as the cutting blade wears and exceeds the preset threshold value. This may result in a misjudgment as a machining abnormality.

Contrary to the above, as the feature value decreases as the cutting blade wears, the AE value cannot exceed the preset threshold even though a machining abnormality has actually occurred. , it may be erroneously determined that the machining is normal.

The present invention includes a holding means for holding a workpiece, a cutting means including a cutting blade for cutting the workpiece held by the holding means, and a cutting water supply means for supplying cutting water to the cutting blade. , a cutting feed means for relatively moving the cutting blade and the holding means in the cutting feed direction; and a cutting feed means disposed on the cutting means or the holding means to detect elastic waves generated from the cutting blade during cutting. A cutting device comprising an AE sensor and a control means, wherein the control means detects, with the AE sensor, an elastic wave containing a plurality of frequency components generated when the cutting blade cuts a workpiece. Then, the elastic wave signal detected by the AE sensor is Fourier transformed to identify two or more frequency bands of the elastic wave signal likely to be generated from the cutting blade, and the elastic wave signal within a predetermined time is calculated. Record the AE value of the specific frequency band, predict the AE value of the frequency band of the elastic wave signal during cutting from the recorded AE value, and predict the AE value of the frequency band of the actually measured elastic wave signal. It is equipped with a control means for detecting processing abnormalities such as chipping based on the difference with the AE value.

The control means specifies two or more frequency bands from the elastic wave signal and continuously records the AE values measured in the specific frequency bands.
Further, the control means predicts the AE value according to the wear of the cutting blade by calculating a polynomial representing an approximate value from the elastic wave signals recorded within a predetermined time using the least squares method.

In the control means, for all the elastic wave signals recorded within a predetermined time, the AE value (predicted AE value) of the specific frequency band predicted by a polynomial representing an approximate value from the elastic wave signal within the time and the By determining the difference between the AE value of the specific frequency band actually recorded within the time (actually measured AE value), the magnitude of variation in the elastic wave signal is determined without being affected by fluctuations due to cutting blade wear. The dispersion-covariance matrix can be determined by using the magnitude of dispersion of elastic wave signals measured in two or more frequency bands.
In addition, the control means calculates all the predicted AE values and actual measured AE values recorded within the time from the above-mentioned variance-covariance matrix and the difference value between the predicted AE value and the actual measured AE value of two or more frequency bands. The degree of deviation from the average (Mahalanobis general distance) can be determined by considering the correlation between the differences in .
A cutting device that can determine that there is an abnormality in the cutting process by comparing the Mahalanobis generalized distance with a preset threshold value or the like.

It is a perspective view showing the whole cutting device. It is a perspective view showing the elements which constitute a cutting means. It is a sectional view showing a cutting means. It is a graph showing a time axis waveform of an elastic wave signal. It is a graph showing a frequency axis waveform of an elastic wave signal. It is a graph showing a tendency of change in an elastic wave signal. It is a graph showing the correlation of elastic wave signals and outliers.

1 Configuration of Cutting Apparatus As shown in FIG. 1, the cutting apparatus 1 cuts the surface Wa of the workpiece W held by the holding means 15 with the cutting blade 43 provided in the cutting means 40, thereby cutting the workpiece W. This is a cutting device for cutting. Although the cutting device 1 shown in FIG. 1 is a dual dicer equipped with two cutting means 40, the cutting device is not limited to this, and may be a cutting device equipped with one cutting means. A device D is provided in each area defined by a dividing line L formed on the surface Wa of a workpiece W such as a semiconductor wafer, and a cutting blade 43 is used to cut the workpiece W along the dividing line L. By doing so, the workpiece W can be divided into individual devices D. An adhesive tape T is attached to the back surface Wb of the workpiece W, and the end of the adhesive tape T attached to the workpiece W is attached to the annular frame F, so that the A workpiece W is supported by a frame F. The cutting device 1 includes a base 10 and a gate-shaped column 13 erected on the −X side of the base 10.

At the center of the base 10 are provided a holding means 15 which is a circular plate-shaped table, a cover 11 surrounding the holding means 15 from below, and a bellows cover 12 connected to the cover 11. The holding means 15 includes a suction section 150 and a frame 151 that supports the suction section 150, and the upper surface of the suction section 150 serves as a holding surface 150a on which the workpiece W is placed. A suction means 80 is disposed below the holding means 15, and the holding surface 150a and the suction means 80 are connected. By transmitting the suction force generated by the suction means 80 to the suction unit 150 with the workpiece W placed on the holding surface 150a, the workpiece W can be suctioned and held on the holding surface 150a.

Further, four clamps 17 are arranged adjacent to the holding means 15 so as to surround the holding means 15 from all sides, and the workpiece W supported by the annular frame F is mounted on the holding surface 150a. The workpiece W can be fixed to the holding means 15 by placing the frame F and clamping it from all sides using four clamps 17. Further, a bottomed cylindrical casing 83 is connected to the lower side of the holding means 15, and inside the casing 83, a rotating means 81 for rotating the holding means 15 around a rotation shaft 82 in the Z-axis direction is provided. is installed.

The interior of the base 10 is provided with a cassette storage area 20 that stores a cassette (not shown) that holds a workpiece W. The upper surface of the cassette storage area 20 is a stage 22, and the stage 22 on which the cassette holding the workpiece W is placed is moved up and down by the cassette lifting means 21 to adjust the height position of the cassette. be done.

A cleaning means 24 is disposed on the base 10 at a position facing the cassette lifting means 21 with the holding means 15 in between. The cleaning means 24 is equipped with a spinner table 25 and a cleaning water nozzle 26. The spinner table 25 holding the workpiece W is lowered into the base 10 by a lifting means (not shown), and cleaning water is sprayed from the cleaning water nozzle 26 while rotating the spinner table 25 by a rotating means (not shown). The workpiece W can be cleaned. Further, after cleaning the workpiece W, the jetting of the cleaning water is stopped and the workpiece W is continuously rotated, so that water droplets adhering to the surface Wa are blown toward the outside of the surface Wa. Thereby, the surface Wa of the workpiece W can be dried.

A cutting feed means 18 is disposed inside the base 10. The cutting feed means 18 includes a ball screw 180 having a rotation axis 184 in the X-axis direction, a pair of guide rails 181 arranged parallel to the ball screw 180, a motor 182 connected to one end of the ball screw 180, and an internal nut. The structure includes a movable plate 183 that is screwed into a ball screw 180 and whose bottom part slides into guide rail 181. Furthermore, the movable plate 183 supports the holding means 15 via the casing 83. When the ball screw 180 is driven by the motor 182 and rotates around the rotation axis 184 in the X-axis direction, the movable plate 183 is guided by the guide rail 181 and moves in the cutting feed direction that is the X-axis direction. The holding means 15 supported by the movable plate 183 via the movable plate 183 moves in the X-axis direction together with the movable plate 183. Note that when the holding means 15 moves in the X-axis direction, the cover 11 surrounding the holding means 15 moves integrally with the holding means 15 in the X-axis direction, and when the cover 11 moves in the X-axis direction, the bellows The cover 12 will expand and contract.

Two cutting means 40 are arranged on the left and right side walls of the gate-shaped column 13, respectively. The two cutting means 40 are constructed in the same way, and their constituent elements are given the same reference numerals.

The cutting means 40 includes a cutting blade 43, a spindle 42 that supports the cutting blade 43, and a rectangular cylindrical spindle housing 41 that accommodates the spindle 42. A blade cover 45 is attached to the spindle housing 41. The central portion of the blade cover 45 is provided with an opening for attaching the cutting blade 43, and covers an area extending from above to the sides of the outer peripheral edge of the cutting blade 43. Further, a cutting water supply provided at the lower part of the blade cover 45 is provided with a nozzle that supplies cutting water to the cutting blade 43 and the part where the workpiece W and the cutting blade 43 come into contact when cutting the workpiece W. The means 46 is attached to be movable up and down, and during cutting, water is supplied to the cutting water supply means 46 from a cutting water supply source (not shown), and the water is supplied to the cutting blade 43 and the workpiece W from the cutting water supply means 46. The workpiece W is cut while supplying cutting water to the portion that contacts the cutting blade 43.

As shown in FIGS. 2 and 3, a cover member 47 that covers the front end side of the spindle 42 is attached to the front end surface 41a of the spindle housing 41. A pair of brackets 48 are disposed on the cover member 47, and the cover member 47 is screwed to the spindle housing 41 via the brackets 48 with the tip of the spindle 42 protruding from the opening 49 of the cover member 47. The cover member 47 and the spindle 42 are connected to each other.

The blade mount 51 includes a disk-shaped flange portion 56 and a boss portion 53 formed on a surface 56a (−Y direction side) of the flange portion 56. As shown in FIG. 3, a fitting hole 52 is formed in the back surface 56b (+Y direction side) of the flange portion 56, and the fitting hole 52 is fitted to the tip of the spindle 42. A circular recess 54 is formed in the boss portion 53, and a through hole 55 connected to the fitting hole 52 is formed in the bottom surface of the circular recess 54. With the tip end surface 42a of the spindle 42 exposed through the through hole 55 of the blade mount 51, the spindle 42 is fitted into the blade mount 51, and the fixing bolt 59 is inserted into the screw hole 44 of the tip end surface 42a of the spindle 42 through the washer 58. The blade mount 51 is fixed to the spindle 42 by being tightened.

The cutting blade 43 is a hub blade equipped with a circular hub base 61 and a cutting blade 62 arranged annularly on the outer periphery of the hub base 61, and an insertion hole 63 is provided inside the circle of the hub base 61. is formed. This insertion hole 63 is pushed into the boss portion 53, and the boss portion 53 is projected from the hub base 61. Then, a fixing nut 65 is tightened on a male thread 57 formed on a protruding portion of the boss portion 53, and the cutting blade 43 is fixed to the blade mount 51.

The cutting blade 62 is formed to have a predetermined thickness by mixing abrasive grains such as diamond or CBN with a binding material such as metal or resin. Note that the cutting blade 43 may be a washer blade that includes only the cutting blade 62.

As shown in FIG. 3, an AE sensor 71 is disposed on the flange portion 56 of the blade mount 51. The AE sensor 71 has a piezoelectric element, and can convert elastic waves generated from the cutting blade 43 during cutting and transmitted to the blade mount 51 into an elastic wave signal, which is an electrical detection signal, and output the signal. can.

In the boundary area between the blade mount 51 and the cover member 47, a first coil means 73 is connected to the AE sensor 71 on the blade mount 51 side, and further connected to the first coil means 73 on the cover member 47 side. A second coil means 74 is connected. When an elastic wave is detected by the AE sensor 71, the elastic wave signal is transmitted from the AE sensor to the first coil means 73, and further, the first coil means 73 is transmitted to the second coil means by magnetic mutual induction. 74.

Control means 75 are connected to second coil means 74 which are magnetically coupled to first coil means 73 . The control means 75 includes an analysis means 76 that performs frequency analysis on the time-domain waveform detected by the AE sensor 71, and a determination means 77 that determines whether chipping is formed based on the result of the frequency analysis. After the elastic wave signal detected by the AE sensor 71 is transmitted to the control means 75 via the first coil means 73 and the second coil means 74, its time axis waveform is Fourier transformed in the analysis means 76. It will be converted to a frequency axis waveform.

The control means 75 is also provided with a notification means 78 for notifying an operator or the like when it is determined by the determination means 77 that chipping has occurred.

As shown in FIG. 1, the portal column 13 is equipped with an indexing feed means 30 and a cutting feed means 35 for moving the two cutting means 40 configured as described above in the Y-axis direction and the Z-axis direction, respectively. .

The indexing and feeding means 30 includes a ball screw 33 having an axis in the Y-axis direction, a motor 34 that rotates the ball screw 33 around a rotating shaft 330 parallel to the Y-axis, and a guide arranged parallel to the ball screw 33. A movable plate 32 is provided, the rail 31 and a side nut being screwed onto a ball screw 33 so as to be in sliding contact with the guide rail 31. When the ball screw 33 is driven by the motor 34 and rotates around the rotating shaft 330, the movable plate 32 is guided by the guide rail 31 and moves in the Y-axis direction.

Further, the cutting feed means 35 includes a ball screw 38 having an axis in the Z-axis direction, a motor 39 that rotates the ball screw 38 around a rotating shaft 380 parallel to the Z-axis, and a motor 39 arranged parallel to the ball screw 38. The support member 37 has a side nut screwed onto a ball screw 38 and slidably contacts the guide rail 36. When the ball screw 38 is rotated by being driven by the motor 39, the support member 37 is guided by the guide rail 36 and moves in the Z-axis direction.

A spindle housing 41 is connected to the lower end of the support member 37, and when the support member 37 moves in the Y-axis direction and the Z-axis direction, the cutting means 40 similarly moves in the Y-axis direction and the Z-axis direction. .

An alignment means 9 is arranged on the side surface of the spindle housing 41. The alignment means 9 includes a camera 90 that takes an image of the workpiece W, and the camera 90 includes, for example, a light irradiation section that irradiates light onto the workpiece W, and an optical system that captures reflected light from the workpiece W. It is equipped with an imaging device (CCD) that outputs an electrical signal corresponding to the reflected light. The alignment means 9 can detect the planned dividing line L of the workpiece W to be cut based on the image acquired by the camera 90. The alignment means 9 and the cutting means 40 are integrally constructed, and both move in conjunction with each other in the Y-axis direction and the Z-axis direction.
2 Operation of cutting equipment

(cutting)
The operation of the cutting device 1 when cutting the workpiece W with the cutting device 1 described above will be described. Note that an adhesive tape T is attached to the workpiece W, and the workpiece W is fixed by the frame F by holding the adhesive tape T in this state by the annular frame F.

First, in the cassette storage area 20, the stage 22 is raised by the cassette lifting means 21, and the cassette on which the workpiece W fixed to the frame F is mounted is positioned above the base 10, and then an arm or the like (not shown) The annular frame F is gripped and placed on the holding surface 150a of the holding means 15, and the suction force generated by the suction means 80 is transmitted to the holding surface 150a to suction the workpiece W on the holding surface 150a. Hold. Then, the frame F is clamped and fixed from all sides by four clamps 17.

Thereafter, by rotating the ball screw 180 around the rotating shaft 184 by the driving force of the motor 182 of the cutting feed means 18, the movable plate 183 and the holding means 15 supported by the movable plate 183 are moved along the guide rail 181 by -X The workpiece W, which is suction-held by the holding means 15, is positioned below the alignment means 9. After the workpiece W is positioned below the alignment means 9, the surface Wa of the workpiece W is imaged by the camera 90. An image of the surface Wa of the workpiece W captured by the camera 90 is subjected to image processing such as pattern matching by the alignment means 9, and a planned dividing line L into which the two cutting blades 43 should be cut is detected.

As the line L to be divided is detected by the alignment means 9, the cutting means 40 is driven in the Y-axis direction by the indexing and feeding means 30, so that the line L to be cut and the cutting blade 43 are aligned in the Y-axis direction. Alignment is performed. In aligning the planned dividing line L and the cutting blade 43 in the Y-axis direction, the ball screw 33 is rotated around the rotation axis 330 by the motor 34 of the indexing and feeding means 30 based on the result of the pattern matching described above. Accordingly, the movable plate 32 moves in the Y-axis direction along the guide rail 31, and the support member 37 connected to the movable plate 32 and the cutting means 40 supported by the support member 37 move in the Y-axis direction. .

After the alignment in the Y-axis direction is completed, the spindle 42 of the cutting means 40 is rotated by a motor (not shown), and the cutting blade 43 connected to the spindle 42 is rotated. While the cutting blade 43 is rotating, the ball screw 38 is driven by the motor 39 of the cutting feed means 35 to rotate the ball screw 38 around the rotating shaft 380, and the cutting blade 43 is lowered in the Z-axis direction. Thereby, the cutting blade 43 is positioned at a height position for starting cutting.

As described above, after the cutting blade 43 is positioned at the planned division line L to be cut and further positioned at the height position for starting the cutting process, the cutting process is started. At that time, the holding means 15 that holds the workpiece W is further sent out in the −X direction at a predetermined cutting feed rate, so that the holding means 15 and the cutting blade 43 are relatively moved at a predetermined speed in the cutting feed direction ( (X-axis direction), the cutting blade 43 cuts into the detected dividing line L of the workpiece W while rotating at high speed, and the dividing line L is cut.

Next, the cutting means 40 is indexed and fed in the Y-axis direction by the interval between adjacent planned dividing lines L, and the same cutting is performed to cut the scheduled dividing line L next to the already cut planned dividing line L. By repeating the indexing and cutting in this way, all of the planned division lines L in the same direction are cut. Then, the holding means 15 is rotated by 90 degrees by the rotating means 81, and then similar cutting is performed, so that all the planned division lines L are cut vertically and horizontally, and the workpiece W can be divided into individual chips.

Note that the following processing conditions are used for the cutting process.
Cutting blade: Abrasive grain size #2000 to #3000
Cutting blade width (kerf width): 20-30μm
Workpiece material: Silicon Cutting feed rate: 50-100mm/sec
Spindle rotation speed: 20000min-1 ~ 30000min-1

(Chipping detection)
While the cutting device 1 is operated to cut the workpiece W as described above, an elastic wave including a plurality of frequency components is generated during cutting by the AE sensor 71 attached to the blade mount 51 of the cutting means 40. is detected, and the detected elastic waves are magnetically transmitted to the first coil means 73 and the second coil means 74, and transmitted to the control means 75 as an electric signal. The control means 75 acquires information shown in FIG. 4, for example. In FIG. 4, the horizontal axis is time (t), and the vertical axis is the AE value (V), which is the value of the elastic wave signal detected by the AE sensor 71 during cutting, and data on temporal changes in the AE value of the elastic wave. A graph of a time axis waveform representing time characteristic data is drawn.

Using the analysis means 76, Fourier transform (for example, FFT) is performed on the temporal characteristic data of the elastic wave signal, with the sampling time To set to 1 millisecond, for example. As a result, frequency characteristic data, which is the spectrum of the elastic wave signal decomposed into each frequency, is obtained. Figure 5 is a frequency-axis waveform graph in which the frequency characteristic data of an elastic wave signal is plotted, with the horizontal axis representing the frequency (f) and the vertical axis representing the size (intensity) of the elastic wave spectrum resolved for each frequency. be.

It is known that the frequency band of elastic waves generated by contact between the cutting blade 43 and the workpiece W during cutting is a specific frequency band of 200 kHz to 600 kHz. Note that vibrations with a frequency smaller than 200kHz are caused by the sound of cutting water supplied from the cutting water supply means 46, noise from the drive unit, etc., and vibrations with a frequency larger than 600kHz are caused by noise from the motor driver, etc. be. Therefore, in the analysis means 76, as shown in FIG. 5, the frequency band from 200 kHz to 600 kHz of the elastic wave signal converted into the frequency axis waveform is identified and divided into four parts of 100 kHz each, and the AE in each frequency band is calculated. Record the value.

The AE value in each frequency band changes as the machining progresses due to reasons such as wear of the cutting blade 43. As shown in the solid line graph of FIG. 6, in addition to random noise components, a specific tendency appears, although it may increase or decrease depending on the frequency band.

The tendency of increase or decrease in the AE value for each frequency band can be drawn as a graph of approximate values as shown in the broken line graph in FIG. This graph of approximate values can be obtained in polynomial expression by the least squares method using a set of AE values for each frequency band. If the polynomial to be sought is a linear equation, it will be an approximate straight line or an approximate plane; if it is a quadratic or higher order equation, it will be an approximate curve or an approximate curved surface.

The cutting distance processed by the cutting blade, the processed quantity of the workpiece, the machine parameters, etc. can be used as explanatory variables for determining the polynomial representing the approximate value. It is desirable that these explanatory variables have a causal relationship with the processing results.

The objective variable for determining the polynomial representing the approximate value is the AE value of each frequency band. In other words, when the AE value is obtained by dividing the range from 200 kHz to 600 kHz into four frequency bands as shown in FIG. 5, four polynomials representing approximate values can also be obtained.

After obtaining a polynomial representing an approximate value in this way, by inputting the cutting distance machined by the cutting blade, the machined quantity of the workpiece, machining parameters, etc. into this polynomial as explanatory variables, the objective variable It is possible to obtain a predicted value of the AE value for each frequency bandwidth. This value is just a prediction and is different from the actually measured AE value for each frequency bandwidth. By calculating the difference between this predicted value and the actually obtained AE value of each frequency bandwidth, it is possible to obtain the difference between the predicted value obtained from the processing parameters and the like.

This difference from the predicted value can be regarded as a deviation in the AE value that is not affected by variations in machining parameters, and by referring to the magnitude of the absolute value of the deviation, it is possible to determine the difference from the machining situation assumed by the cutting equipment. can be judged.

However, although this deviation has a different value for each frequency band, the magnitude of the AE value also changes uniformly due to variations in processing load, so there is a certain correlation between multiple frequency bands as shown in Figure 7. have. Therefore, it cannot be assumed that a machining abnormality has occurred simply from the fact that the deviation of the AE value in one frequency band is large.

Therefore, by calculating the correlation coefficient from a set of deviations of AE values obtained from two or more frequency bands and obtaining a variance-covariance matrix, we can obtain the Mahalanobis generalized distance of deviations of AE values for each cutting process. Can be done.

This Mahalanobis general distance increases as the distance from the population tendency estimated from the correlation coefficient between deviations of AE values increases. Therefore, since the AE value such as the example of the abnormal value shown in FIG. 7 is far from the space that is considered normal as shown by the set of broken lines, the value of the Mahalanobis general distance becomes large.

If the Mahalanobis generalized distance obtained in this way exceeds a preset threshold, it can be determined that an abnormality in the cutting process that cannot be explained by mere fluctuations in the process load has occurred.

By using the value of the Mahalanobis generalized distance determined as described above, it is possible to more accurately determine whether a machining abnormality such as chipping has occurred.

1: Cutting device 10: Base 11: Cover 12: Bellows cover 13: Portal column 15: Holding means 150: Suction part 150a: Holding surface 151: Frame body 17: Clamp 18: Cutting feed means 180: Ball screw 181: Guide rail 182: Motor 183: Movable plate 184: Rotating shaft 20: Cassette storage area 21: Cassette lifting means 22: Stage 24: Cleaning means 25: Spinner table 26: Washing water nozzle 30: Indexing and feeding means 32: Movable plate 31: Guide rail 33: Ball screw 330: Rotating shaft 34: Motor 35: Cutting feed means 36: Guide rail 38: Ball screw 380: Rotating shaft 39: Motor 40: Cutting means 41: Spindle housing 41a: Tip surface of spindle housing 42: Spindle 43: Cutting Blade 44: Screw hole 45: Blade cover 46: Cutting water supply means 47: Cover member 48: Bracket 49: Opening 51: Blade mount 52: Engagement hole 53: Boss portion 54: Circular recess 55: Through hole 56: Flange portion 57: Male thread 58: Washer 59: Fixing bolt 61: Hub base 62: Cutting blade 63: Insertion hole 65: Fixing nut 71: AE sensor 73: First coil means 74: Second coil means 75: Control means 76: Analysis means 77: Judgment means 78: Notification means 80: Suction means 81: Rotation means 82: Rotation shaft 83: Casing 9: Alignment means 90: Camera W: Workpiece Wa: Surface of workpiece Wb: Workpiece Back side of object T: Adhesive tape F: Frame To: Sampling time

Claims (1)

A holding means for holding a workpiece, a cutting means including a cutting blade for cutting the workpiece held by the holding means, a cutting water supply means for supplying cutting water to the cutting blade, and the cutting blade. and a cutting feed means for relatively moving the holding means in a cutting feed direction; an AE sensor disposed on the cutting means or the holding means and detecting elastic waves generated from the cutting blade during cutting; A cutting device comprising a control means,
The control means detects, with the AE sensor, an elastic wave containing a plurality of frequency components generated when the cutting blade cuts the workpiece, and performs Fourier transform on the elastic wave signal detected by the AE sensor. , identify two or more frequency bands of the elastic wave signals that may be generated from the cutting blade, continuously record the elastic wave signals measured in the specific frequency bands , and within a predetermined time. A polynomial representing an approximate value is obtained from a set of recorded frequency band values of the elastic wave signal, and a predicted value of the frequency band value of the elastic wave signal that will be measured when cutting the workpiece is calculated. and the workpiece in the set of differences between the predicted value of the frequency band value of the elastic wave signal recorded within a predetermined time and the actual value actually measured in the frequency band of the elastic wave signal. The Mahalanobis general distance of the difference between the predicted value and the actual measurement value of each of the two or more elastic wave signals measured during cutting is determined, and when the Mahalanobis general distance exceeds a preset threshold, the cutting blade A cutting device that determines that there is an abnormality in the cutting process when chipping occurs on the kerf that has been cut into the workpiece .

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