JP7158195B2 - Tool wear determination device - Google Patents

Description

The present invention relates to a tool wear determination device for determining the wear state of a tool in a machine tool.

Cutting is a type of removal machining that forms a desired shape on a workpiece through relative motion between the tool and the workpiece. 2. Description of the Related Art Machine tools that perform cutting are devices that perform cutting by rotating a tool and a work mounted on a spindle, as typified by machining centers and lathes. In such a machine tool, as the cutting distance increases, the wear amount of the tip of the tool increases, so it is necessary to replace the tool with a new tool at an appropriate timing. Cutting with a worn tool causes poor machining of the workpiece, such as deterioration of the accuracy of the machined surface of the workpiece and failure to obtain desired machining dimensional accuracy. A defectively machined work must be discarded, and the time required for machining is wasted, lowering productivity.

In order to manage the quality of machining, by replacing the tool with a new one after machining for a predetermined distance or time, it is possible to prevent machining defects caused by using worn tools. is being done. However, in this case, since the tool is replaced regardless of the actual state of the tool, there is the problem of wasting tools that can still be processed, resulting in waste and unnecessary tool replacement work time. There is a problem that productivity decreases.

On the other hand, there has been proposed an apparatus for determining tool wear by measuring and analyzing vibration waveforms of vibrations generated in cutting. Patent Literature 1 discloses a method of detecting tool wear by performing frequency analysis on a vibration waveform and comparing the frequency-analyzed waveform with a threshold value.

JP 2012-76168 A

Machining conditions for cutting include machining conditions that are set in advance and machining conditions that change as the machining progresses. Machining conditions that are set in advance include, for example, spindle speed, feed rate, depth of cut, type of tool to be used, and work material. Examples of machining conditions that change as machining progresses include the shape of the workpiece.

Even if the machining conditions set in advance are the same and the degree of wear of the tool is the same, the vibrations that occur during cutting will not be the same due to the effects of the machining conditions that change as the machining progresses. sometimes it doesn't work. In other words, even if the machining conditions set in advance are the same and the degree of wear of the tool is the same, the vibration generated by cutting is affected by the machining conditions that change as the machining progresses. The amplitude of vibration, the frequency of vibration characteristic of tool wear, etc. may not be the same.

It is known that such changes in vibration are due to changes in the vibration characteristics of the workpiece, which are determined based on the material characteristics, dynamic characteristics, shape information, and the like of the workpiece. In addition, the vibration characteristics of the workpiece also change due to changes in the cutting position, changes in the mechanical positional relationship between the cutting position and the vibration measurement position, or changes in the mechanical positional relationship between the cutting position and the fixed position of the workpiece. It is known.

Therefore, the vibration measured through a series of cutting processes may not be constant due to the influence of machining conditions that change as the machining progresses. The method for detecting wear of a tool described in Patent Document 1 does not take into account the change in vibration that occurs with cutting, and judgment based on the frequency analysis waveform and the same threshold results in an erroneous judgment. I had a problem with the possibility.

The present invention has been made in view of the above, and provides a tool wear determination device capable of determining the wear state of a tool by suppressing erroneous determination caused by changes in the vibration characteristics of a work as cutting progresses. for the purpose.

In order to solve the above-described problems and achieve the object, a tool wear determination device according to the present invention is a tool wear determination device for determining the wear state of a tool for cutting a workpiece in a machine tool. The tool wear determination device includes a state quantity acquisition unit that acquires a state quantity of the machine tool including vibration data representing vibration generated in the machine tool or the work during cutting of the work by the machine tool, and the state quantity acquired by the state quantity acquisition unit. and a machining condition evaluation unit for judging whether or not the machining conditions indicated by the state variables of the machine tool other than the vibration data are suitable for judging the wear state of the tool. In addition, the tool wear determination device includes a vibration feature amount calculation unit that calculates a vibration feature amount representing the characteristics of vibration generated in the machine tool or the workpiece based on the vibration data, and a machining condition determination that is the determination result of the machining condition evaluation unit. and a wear state determination unit that determines whether or not the tool is in a wear state based on the vibration feature amount when the result is a determination result that the tool is suitable for determining the wear state of the tool. The machining condition evaluation unit analytically calculates the vibration characteristics of the machine tool or the workpiece based on the state quantities of the machine tool other than the vibration data, and calculates the state quantities of the machine tool other than the vibration data based on the calculated vibration characteristics. determines in advance whether or not the machining conditions are suitable for determining the wear state of the tool for a plurality of different machining conditions indicated by Information indicating the relationship with the determination result of whether or not is stored in advance. Based on the information indicating the relationship, the machining condition evaluation unit determines whether the machining condition indicated by the state quantity of the machine tool other than the vibration data acquired by the state quantity acquisition unit is suitable for determining the wear state of the tool. determine whether or not

ADVANTAGE OF THE INVENTION According to this invention, it is effective in the tool wear determination apparatus which can determine the wear state of a tool by suppressing the erroneous determination resulting from the change of the vibration characteristics of a workpiece|work with progress of cutting.

1 is a block diagram showing the configuration of a tool wear determination device according to Embodiment 1 of the present invention; FIG. 1 is a schematic diagram showing the configuration of a machine tool in which the wear state of a tool is determined by the tool wear determination device according to the first embodiment of the present invention; FIG. 2 is a diagram showing an example of a hardware configuration of a processing circuit according to Embodiment 1 of the present invention; FIG. 2 is a diagram for explaining the difference in vibration characteristics depending on the machining path of the workpiece in Embodiment 1 of the present invention; FIG. 2 is a diagram for explaining the difference in vibration characteristics of a workpiece depending on the shape of the workpiece in Embodiment 1 of the present invention; FIG. 4 is a diagram showing another method of fixing a work according to Embodiment 1 of the present invention; 1 is a flow chart showing an example of processing between a machine tool and a tool wear determination device according to Embodiment 1 of the present invention; A block diagram showing the configuration of a tool wear determination device according to Embodiment 2 of the present invention. Flowchart showing an example of processing between a machine tool and a tool wear determination device according to Embodiment 2 of the present invention Flowchart showing an example of another process of the machine tool and the tool wear determination device according to Embodiment 2 of the present invention Block diagram showing the configuration of a tool wear determination device according to Embodiment 3 of the present invention Flowchart showing an example of processing between a machine tool and a tool wear determination device according to Embodiment 3 of the present invention

A tool wear determination device according to an embodiment of the present invention will be described in detail below with reference to the drawings. In the following description, the same components are denoted by the same reference numerals, and repeated descriptions are omitted. In addition, this invention is not limited by this embodiment.

Embodiment 1.
FIG. 1 is a block diagram showing the configuration of a tool wear determination device 1 according to Embodiment 1 of the present invention. FIG. 2 is a schematic diagram showing the configuration of the machine tool 12 in which the wear state of the tool is determined by the tool wear determination device 1 according to the first embodiment of the present invention.

The tool wear determination device 1 is a tool wear determination device that determines the wear state of a tool 124 that cuts a work 31 in the machine tool 12. The tool wear determination device 1 is mounted on the machine tool 12 and cuts the work 31 that is fixed to the machine tool 12. It is a tool wear determination device that determines the wear state of a tool 124 to be machined. The tool wear determination device 1 includes a state quantity acquisition unit 21 for acquiring state quantities of the machine tool including vibration data representing vibrations generated in the machine tool 12 or the work 31 during cutting of the work 31 by the machine tool 12; a machining condition evaluation unit 22 that determines whether or not the machining conditions indicated by the state quantities of the machine tool other than the vibration data acquired by the acquisition unit 21 are suitable for determining the wear state of the tool 124. . The tool wear determination device 1 also includes a vibration feature quantity calculation unit 23 for calculating a vibration feature quantity representing the characteristics of vibration generated in the machine tool 12 or the workpiece 31 based on the vibration data, and the determination result in the machining condition evaluation unit 22. A wear state determination unit 24 that determines whether the tool 124 is in a wear state based on the vibration feature amount when the machining condition determination result is suitable for determining the wear state of the tool. And prepare.

In the tool wear determination device 1 according to the first embodiment, the sensor 13 arranged in the machine tool 12 in which the tool wear determination device 1 determines the wear state of the tool 124 is connected to the state quantity acquisition unit 21. there is In the tool wear determination device 1 , a numerical control device 11 that is connected to a machine tool 12 and controls the operation of the machine tool 12 is connected to a state quantity acquisition section 21 .

As shown in FIG. 2, the machine tool 12 is, for example, a vertical machining center having a structure in which a rotating shaft is provided in a vertical direction and a workpiece 31 is machined from above. The machine tool 12, which is a vertical machining center, is provided with a rotatable main shaft 123 on a main shaft head 122 provided at the upper part of a main body 121, and is arranged below the tool 124 by the tool 124 attached to the main shaft 123. It has a well-known configuration for processing the workpiece 31 set on the processing table 125 . A sensor 13 is installed on the side surface of the workpiece 31 as a vibration detection unit for measuring vibration. Note that the sensor 13 may be installed on the machine tool 12, or may be installed, for example, on the processing table 125 on which the workpiece 31 is fixed. An acceleration sensor or the like is used as the sensor 13, for example.

The state quantity acquisition unit 21 acquires the state quantity of the machine tool during cutting of the workpiece 31 and transmits the state quantity to the machining condition evaluation unit 22 and the vibration feature quantity calculation unit 23 . The state quantity of the machine tool acquired by the state quantity acquisition unit 21 includes at least vibration data that is vibration data generated in the machine tool 12 or the work 31 as the machine tool 12 cuts the work 31 . Hereinafter, the vibration that occurs in the machine tool 12 or the work 31 as the machine tool 12 cuts the work 31 may be simply referred to as vibration.

The state quantity acquisition unit 21 can acquire vibration data from the measurement result of the sensor 13, for example. The sensor 13 is installed in the machine tool 12 to measure vibration generated in the machining table 125 provided in the machine tool 12 , or is installed in the workpiece 31 on the machining table 125 to measure vibration generated in the workpiece 31 . In addition, the state quantity acquisition unit 21 obtains the machining table 125 or the machining table from the feedback value of the servo motor that controls the movement of the machining table 125 provided in the machine tool 12 via the numerical control device 11 connected to the machine tool 12 . Vibration data representing the vibration occurring in the workpiece 31 on 125 can be obtained.

In addition, the state quantity of the machine tool other than the vibration data includes the cutting position coordinates in the cutting of the workpiece 31 in the machine tool 12 . The state quantity acquisition unit 21 can acquire the cutting position coordinates in the cutting of the work 31 based on the detection result of a sensor installed in the machine tool 12 for detecting the position of the tool 124, for example. Also, the state quantity acquisition unit 21 can acquire the cutting position coordinates in the cutting of the workpiece 31 from, for example, the feedback value of the servo motor that controls the movement of the machining table 125 provided in the machine tool 12 .

The machining condition evaluation unit 22 determines that the machining condition indicated by the state quantity of the machine tool other than the vibration is based on the state quantity of the machine tool other than the vibration among the state quantities of the machine tool acquired by the state quantity acquisition unit 21. It determines whether the machining conditions are suitable for determining the wear state of the tool 124 attached to the machine 12 , and transmits the determination result to the wear state determination unit 24 . For example, the machining condition evaluation unit 22 collates the cutting position coordinates acquired by the state quantity acquisition unit 21 with a machining program including shape information, which is information on the shape of the workpiece 31 . Then, when the distance between the end of the workpiece 31 and the cutting position coordinates is equal to or greater than a predetermined threshold distance, the machining condition evaluation unit 22 determines that the cutting position coordinates acquired by the state quantity acquisition unit 21 correspond to those of the tool 124. It is determined that the machining conditions are suitable for determining the state of wear.

Here, the cutting position coordinates are coordinates representing a three-dimensional position. The machining condition evaluation unit 22 may store the machining program in advance, or may acquire the machining program from the numerical controller 11 . The threshold distance is a threshold for determining whether or not the cutting position coordinates acquired by the state quantity acquisition unit 21 are machining conditions suitable for determining the wear state of the tool 124, and is stored in advance in the machining condition evaluation unit 22. be done.

The vibration feature amount calculation unit 23 calculates a vibration feature amount representing the characteristics of the vibration generated in the machine tool 12 or the work 31 based on the vibration data during cutting of the work 31 acquired by the state quantity acquisition unit 21, and determines the wear. It is transmitted to the state determination unit 24 . A general signal processing technique known for analysis of time-series data can be used to calculate the vibration feature quantity. The vibration feature amount calculator 23 calculates, as the vibration feature amount, the average value, effective value, amplitude, kurtosis, skewness, or A feature amount based on the crest factor is calculated. The crest factor is also called the crest factor. Further, the vibration feature amount calculation unit 23 calculates the frequency spectrum obtained by Fourier transforming the time-series data of the vibration data representing the vibration generated with the progress of the cutting of the workpiece 31 in the machine tool 12 as the vibration feature amount, for example. Calculate the feature amount based on

Regarding the frequency spectrum, for example, it is possible to focus on the frequency corresponding to the rotation of the tool and the frequency that is an integral multiple of the frequency, and to calculate the feature value based on the power spectrum at these frequencies. As for the frequency spectrum, for example, focusing on the frequency obtained by multiplying the frequency corresponding to the rotation of the tool by the number of teeth of the tool and the frequency that is an integral multiple of this frequency, the feature amount is calculated based on the power spectrum at these frequencies. can be calculated. Also, the time-series waveform of the vibration data representing the vibration generated as the cutting of the workpiece 31 progresses in the machine tool 12 exhibits periodicity for each rotation of the tool, and therefore may be based on autocorrelation.

The wear state determination unit 24 determines that the machining conditions indicated by the state quantities of the machine tool other than vibration among the state quantities of the machine tool acquired by the state quantity acquisition unit 21 are suitable for determining the wear state of the tool 124. The wear state of the tool 124 is determined based on the vibration feature amount calculated by the vibration feature amount calculator 23 when the machining condition evaluation unit 22 determines. For example, the wear state determination unit 24 compares the vibration feature amount calculated by the vibration feature amount calculation unit 23 with a predetermined threshold feature amount, and if the vibration feature amount exceeds the threshold feature amount, the tool 124 is in a worn state. The threshold feature value is a threshold value for determining the wear state of the tool 124 based on the vibration feature value calculated by the vibration feature value calculation unit 23, and is stored in the machining condition evaluation unit 22 in advance.

The state quantity acquisition unit 21 is realized, for example, as a processing circuit having the hardware configuration shown in FIG. FIG. 3 is a diagram showing an example of a hardware configuration of a processing circuit according to Embodiment 1 of the present invention. When the state quantity acquisition unit 21 is implemented by the processing circuit shown in FIG. 3, the state quantity acquisition unit 21 is implemented by the processor 101 executing a program stored in the memory 102 . Also, multiple processors and multiple memories may work together to achieve the above functions. Also, part of the functions of the state quantity acquisition unit 21 may be implemented as an electronic circuit, and other parts may be realized using the processor 101 and the memory 102 .

Further, each of the machining condition evaluation unit 22, the vibration feature amount calculation unit 23, and the wear state determination unit 24 is similarly configured to be realized by the processor 101 executing a program stored in the memory 102. may In addition, a plurality of processors and a plurality of memories may work together to realize the functions of the machining condition evaluation unit 22, the vibration feature amount calculation unit 23, and the wear state determination unit 24. Further, part of the functions of the machining condition evaluation unit 22, the vibration feature value calculation unit 23, and the wear state determination unit 24 are implemented as an electronic circuit, and the other functions are realized using the processor 101 and the memory 102. You may make it

Further, the processor and memory for realizing one of the machining condition evaluation unit 22, the vibration feature value calculation unit 23, and the wear state determination unit 24 include the state quantity acquisition unit 21, the machining condition evaluation unit 22, and the The processor and memory may be the same as the processor and memory that implement the other components of the vibration feature quantity calculation unit 23 and the wear state determination unit 24, or may be separate processors and memories.

Further, the display device 14 is connected to the wear state determination section 24 . The display device 14 has a display, for example, and displays various information in the tool wear determination device 1 . For example, the display device 14 acquires the determination result of the wear state of the tool 124 in the wear state determination unit 24 from the wear state determination unit 24 and displays it. That is, when the display device 14 receives the determination result of the wear state of the tool 124 in the wear state determination unit 24 from the wear state determination unit 24, the display device 14 displays a predetermined character string corresponding to the received determination result of the wear state of the tool 124. display. That is, when the display device 14 receives the determination result that the tool 124 is in a worn state from the worn state determination unit 24, the display device 14 displays a message that the tool 124 is in a worn state.

The reason why the tool wear determination device 1 according to the first embodiment includes the machining condition evaluation unit 22 is as follows. When the work 31 is cut by the machine tool 12, the machining conditions such as the spindle speed, the feed rate, the depth of cut, the type of the tool 124 to be used, and the material of the work 31 are set before the work 31 is cut. is set in the machining program stored in the numerical controller 11 in advance.

Even if the machining conditions set in advance are the same and the degree of wear of the tool 124 is the same, the vibration generated as the cutting of the workpiece 31 progresses in the machine tool 12 does not affect the progress of the cutting. It may not be the same due to the influence of processing conditions that change with time. That is, even if the machining conditions set in advance are the same and the degree of wear of the tool 124 is the same, the amplitude of vibration generated in cutting, the frequency of characteristic vibration indicating wear, etc. However, it may not be the same due to the influence of machining conditions that change with the progress of cutting.

In other words, machining conditions for cutting include machining conditions that are set in advance and machining conditions that change as the cutting progresses. The machining conditions that change as the cutting progresses are the machining conditions indicated by the state quantities of the machine tool other than the vibration data described above. Then, even if the degree of wear of the tool 124 is the same due to the influence of the machining conditions that change as the cutting progresses, the wear of the workpiece 31 in the machine tool 12, which is measured by the sensor 13, is generated along with the cutting of the work 31 in the machine tool 12. may change the vibration that you hear.

Such changes in vibration are due to changes in vibration characteristics determined based on the material characteristics, dynamic characteristics, and shape of the workpiece 31. For example, changes in cutting position on the same plane, cutting position and vibration measurement position , changes in the mechanical positional relationship between the fixing position and the cutting position of the workpiece 31, or differences in the mechanical structure of the machine tool 12, the amplitude and frequency of the vibrations described above. is known to change. The mechanical structure of the machine tool 12 includes the fixing position and fixing method of the workpiece 31 to the machine tool 12 .

FIG. 4 is a diagram for explaining the difference in vibration characteristics depending on the machining path of the workpiece in Embodiment 1 of the present invention. Hereinafter, changes in vibration characteristics will be described by taking as an example the case where the machine tool 12 performs cutting on the workpiece 31 shown in FIG. The flat workpiece 31 is fastened to the upper surface of the processing table 125 of the machine tool 12 by bolts (not shown) at four fixing portions, that is, the fixing portion 32a, the fixing portion 32b, the fixing portion 32c, and the fixing portion 32d. 125. It is also assumed that a sensor 13 for measuring vibration is installed on the side surface 31c of the workpiece 31. As shown in FIG. Consider the case of cutting a linear machining path a parallel to the longitudinal direction of the workpiece 31 from one end 31a side to the other end 31b side in the longitudinal direction of the workpiece 31 under the above conditions.

When the vibration characteristics described above are qualitatively considered, the machining path a consists of five small paths a1, a2, a3, a4, and a5 from one end 31a in the longitudinal direction of the workpiece 31. It can be thought of as being divided into paths. The minor path a1 is a machining path closest to the one end 31a in the longitudinal direction of the workpiece 31 in the machining path a. The minor path a5 is a machining path closest to the other end 31b in the longitudinal direction of the workpiece 31 in the machining path a.

The fixing portion 32a and the fixing portion 32c are arranged in a region on the one end 31a side in the in-plane direction of the upper surface of the workpiece 31 . The fixing portion 32a and the fixing portion 32c are arranged at line-symmetrical positions in the in-plane direction of the upper surface of the workpiece 31 with the machining path a interposed therebetween. The fixing portion 32b and the fixing portion 32d are arranged in a region on the other end 31b side of the upper surface of the workpiece 31 in the in-plane direction. The fixed portion 32b and the fixed portion 32d are arranged at line-symmetrical positions in the in-plane direction of the upper surface of the workpiece 31 with the machining path a interposed therebetween. The in-plane direction of the upper surface of the workpiece 31 is parallel to the in-plane direction of the processing table 125 .

The small path a1 is an area surrounded by the fixed portions 32a and 32c and the one side 31s1 of the workpiece 31 on the one end 31a side in the in-plane direction of the processing table 125 . The small path a5 is an area surrounded by the fixed portions 32b and 32d and the other side 31s2 of the work 31 on the other end 31b side in the in-plane direction of the processing table 125 . That is, the small path a1 and the small path a5 are defined by any two fixing portions and one end 31a or the other end 31b of the work 31, which is one of the ends of the machining path a, in the in-plane direction of the upper surface of the work 31. is the area enclosed by

Since the side surfaces of the work 31 are not fixed, the amplitude of vibration generated by cutting is amplified and the work 31 is rotated in the in-plane direction of the processing table 125 . The small path a1 is an area relatively closer to the fixed parts 32a and 32c than the small path a3, that is, the area of the small path relatively closer to the fixed part. On the other hand, the small path a1 is an area surrounded by one side 31s1 of the work 31 on the one end 31a side, and is an area adjacent to the one end 31a of the work 31 . For this reason, the small path a1 has a relatively large amplitude of vibration and rotational movement of the workpiece 31 compared to the other small paths. Therefore, the minor path a1 is an area in which the cutting position coordinates, which are machining conditions indicated by the state quantity of the machine tool acquired during cutting of the machining path, are not machining conditions suitable for determining the wear state of the tool 124, that is, This region is considered to be unsuitable for determining the state of wear of the tool 124 .

The minor path a5 is a region relatively closer to the fixed parts 32b and 32d than the minor path a3. On the other hand, the small path a5 is an area surrounded by the other side 31s2 on the other end 31b side of the work 31 and is an area adjacent to the other end 31b of the work 31 . For this reason, in the small path a5, similarly to the small path a1, the amplification of the vibration and the occurrence of rotational motion of the workpiece 31 are relatively large compared to the other small paths. Therefore, the minor path a5 is an area in which the cutting position coordinates, which are machining conditions indicated by the state quantity of the machine tool acquired during cutting of the machining path, are not machining conditions suitable for determining the wear state of the tool 124, that is, This region is considered to be unsuitable for determining the state of wear of the tool 124 .

The minor path a2 is a region relatively closer to the fixed parts 32a and 32c than the minor path a3. For this reason, compared to the small path a3, the small path a2 has a relatively large degree of suppression of vibration generated by cutting by the fixed portions 32a and 32c. It is considered to be an unsuitable area. That is, the small path a2 is considered to be an area unsuitable for determining the wear state of the tool 124 because the degree of vibration amplitude suppression is relatively large.

The minor path a4 is a region relatively closer to the fixed parts 32b and 32d than the minor path a3. For this reason, compared to the small path a3, the small path a4 has a relatively large degree of suppression of vibration generated by cutting by the fixed portions 32b and 32d. It is considered to be an unsuitable area. That is, the small path a4 is considered to be an area unsuitable for determining the wear state of the tool 124 because the degree of vibration amplitude suppression is relatively large.

On the other hand, the minor path a3 is an area surrounded by four fixed parts, but is relatively distant from the stationary part compared to the minor paths a1, a2, a4, and a5. be. Since the small path a3 is an area surrounded by the four fixed parts, vibrations generated along with cutting are stably generated. In addition, since the minor path a3 is relatively far from the fixed portion compared to the minor paths a1, a2, a4, and a5, the minor paths a1, a2, a4, and Compared to the small path a5, the degree of suppression of vibration generated by cutting by the fixing portions 32a, 32c, 32b, and 32d is relatively small. Therefore, the small path a3 is an area where the cutting position coordinates, which are machining conditions indicated by the state quantity of the machine tool acquired during cutting of the machining path, are machining conditions suitable for determining the wear state of the tool 124. , are considered to be regions suitable for determining the state of wear of the tool 124 .

Thus, in the machining path a, there are a region where the vibration generated by cutting is amplified, a region where vibration generated by cutting is suppressed, and a vibration generated by cutting. A region that stably occurs is mixed. Therefore, when determining the wear state of the tool by comparing the vibration data with the same predetermined threshold value, the region where the vibration suitable for determination of the wear state of the tool is measured and the region where the determination of the wear state of the tool is determined. It is considered that the workpiece 31 includes a region where vibrations unsuitable for the measurement are measured. That is, a region where the vibration generated by cutting is amplified, a region where vibration generated by cutting is suppressed, and a region where vibration generated by cutting is stably generated are: It is considered that the vibration transmission characteristics, which are the transmission characteristics when the generated vibration is transmitted to the sensor 13, are different.

From the above, in the machining path a, the cutting position where both the mechanical distance from the fixed part and the mechanical distance from the end of the workpiece 31 are equal to or greater than predetermined values are It can be considered as a region suitable for determining the state of wear of the tool 124 . Here, the end of the work 31 may be any side or face of the work 31 .

Therefore, for example, the machining condition evaluation unit 22 collates the cutting position coordinates, which are the machining conditions indicated by the state quantity of the machine tool acquired by the state quantity acquisition unit 21, with the machining program including the shape information of the workpiece 31, A distance between the cutting position coordinates and the end of the workpiece 31 is calculated. When the distance between the calculated cutting position coordinates and the end of the workpiece 31 is equal to or greater than a predetermined value, the machining condition evaluation unit 22 determines that the cutting position coordinates acquired by the state quantity acquisition unit 21 are the tool 124 It is determined that it is suitable for determining the wear state of That is, the machining condition evaluation unit 22 can calculate the machining condition determination result based on the vibration transmission characteristics between the cutting position and the end of the workpiece 31 at each time during the cutting of the workpiece 31 .

Further, for example, the machining condition evaluation unit 22 collates the cutting position coordinates, which are the machining conditions indicated by the state quantity of the machine tool acquired by the state quantity acquisition unit 21, with the machining program including the shape information of the workpiece 31, The distance between the cutting position coordinates and the fixed position of the workpiece 31 with respect to the machine tool 12 is calculated. When the distance between the calculated cutting position coordinates and the fixed position of the workpiece 31 is equal to or greater than a predetermined value, the machining condition evaluation unit 22 determines that the cutting position coordinates acquired by the state quantity acquisition unit 21 are the tool 124 It is determined that it is suitable for determining the wear state of That is, the machining condition evaluation unit 22 calculates the machining condition determination result based on the vibration transmission characteristics between the cutting position at each time during the cutting of the workpiece 31 and the fixed position of the workpiece 31 with respect to the machine tool 12. be able to.

In addition, the machining condition evaluation unit 22 compares the cutting position coordinates suitable for determining the state of wear set in advance based on the shape information of the workpiece 31 and the cutting position coordinates at each time during cutting of the workpiece 31. Then, when both match, it may be determined that the cutting position coordinates at each time point during the cutting of the workpiece 31 are suitable for determining the wear state of the tool 124 . The cutting position coordinates suitable for determining the wear state of the tool 124 are set by previously cutting a test workpiece having the same shape as the shape information of the workpiece 31 . Each point in time during cutting of the workpiece 31 corresponds to each cutting position during machining.

In this manner, the machining condition evaluation unit 22 uses the cutting position coordinates and the shape information of the workpiece 31 to estimate the vibration characteristics of the machine tool 12 including the workpiece 31 or the workpiece 31 at each time point during machining. , whether or not it is suitable for determining the wear state can be determined based on the estimation result.

FIG. 5 is a diagram for explaining the difference in vibration characteristics of the workpiece 31 depending on the shape of the workpiece 31 according to Embodiment 1 of the present invention. Next, consider a case where the work 31 shown in FIG. 4 is cut, for example, and the work 31 having the shape shown in FIG. 5 is cut along the machining path b. Here, in the workpiece 31 having the shape shown in FIG. 5, the thickness of the cut groove portion 31d is assumed to be less than a predetermined value. The position of the machining path b in the in-plane direction of the upper surface of the workpiece 31 is the same as that of the machining path a.

As the cutting process progresses, the thickness of the workpiece in the area to be processed changes into a thin plate with a thickness less than a predetermined value. It is thought that the natural vibration frequency of the machine tool or workpiece being processed is lowered. Therefore, when the thickness of the workpiece in the region to be processed is less than the predetermined value, the thickness of the workpiece in the region to be processed is reduced to the predetermined value during subsequent cutting of the region to be processed. When the value is greater than or equal to the value, vibration data having a different aspect from the vibration data obtained by cutting the processing target area can be obtained.

That is, due to the influence of the thickness of the workpiece in the machining target area, which is a machining condition that changes as the cutting progresses, the thickness of the workpiece in the machining target area is less than a predetermined value. Measurement is performed by the sensor 13 even when the workpiece thickness is equal to or greater than a predetermined value, the machining conditions set in advance are the same, the degree of wear of the tool is the same, and the cutting position is the same. the vibration received may change. Therefore, it is considered that a region to be processed in which the thickness of the work in the region to be processed is less than a predetermined value is not suitable for determining the state of wear.

From this knowledge, during cutting along the machining path b shown in FIG. It is considered that it is not suitable for the judgment of

Similarly, when the sensor 13 is attached to the machining table 125, during the cutting of the machining path b shown in FIG. Since vibration data of the machine tool 12 with different modalities can be obtained, the machining path b is considered unsuitable for determining the state of wear.

Therefore, for example, the machining condition evaluation unit 22 collates the cutting position coordinates, which are the machining conditions indicated by the state quantity of the machine tool acquired by the state quantity acquisition unit 21, with the machining program including the shape information of the workpiece 31, The thickness of the workpiece 31 at the cutting position at the time of cutting is estimated. When the estimated thickness of the workpiece 31 is equal to or greater than a predetermined value, the machining condition evaluation unit 22 determines that the cutting position coordinates acquired by the state quantity acquisition unit 21 are suitable for determining the wear state of the tool 124. I judge.

As described above, the machining condition evaluation unit 22 considers the shape information of the workpiece 31 at each point in time during the cutting of the workpiece 31, and determines whether the machine tool 12 to which the workpiece 31 is fixed or the machine tool to which the workpiece 31 is fixed. Vibration characteristics of the workpiece 31 fixed to the tool 12 can be estimated, and whether or not the cutting position coordinates are suitable for determining the wear state of the tool 124 can be determined based on the estimation result. Then, when the machining condition evaluation unit 22 determines that the cutting position coordinates acquired by the state quantity acquisition unit 21 are machining conditions suitable for determining the wear state of the tool 124, the vibration feature amount calculation unit 23 calculates Since the wear state determination unit 24 determines the wear state of the tool 124 based on the vibration feature amount obtained, the wear state of the tool 124 is erroneously determined due to changes in the vibration characteristics of the workpiece 31 as the cutting progresses. can be suppressed.

As described above, the amplitude of the characteristic vibration indicating the wear state of the tool and the frequency of the characteristic vibration indicating the wear state of the tool, which are measured during a series of cutting processes for one workpiece, Different values are obtained due to the thickness of the area being cut and the area to be machined, which are machining conditions that change as the process progresses. Therefore, without including the machining condition evaluation unit 22 and without considering the machining conditions that change with the progress of the cutting process, it is suitable for determining the area of the workpiece that is not suitable for determining the wear state of the tool and the wear state of the tool. If the wear state of the tool is determined by comparing the vibration data generated in an arbitrary region with the same threshold without considering the region, an erroneous determination may occur.

On the other hand, the tool wear determination device 1 according to the first embodiment takes into consideration the machining conditions indicated by the state quantities of the machine tool acquired by the state quantity acquiring unit 21, which are machining conditions that change as the cutting progresses. After that, the machining condition evaluation unit 22 can determine machining conditions suitable for determining the wear state of the tool 124. Therefore, even if the vibration amplitude, vibration frequency, etc. change as the cutting progresses, cutting can be performed. It is possible to suppress erroneous determination of the wear state of the tool 124 due to changes in the vibration characteristics of the work as the work progresses.

Considering the mounting position of the sensor 13 that measures vibration, the vibration measured by the sensor 13 may change depending on the mechanical positional relationship between the cutting position coordinates and the fixed position of the workpiece 31 on the machine tool 12. There is For example, when the vibration measurement position and the fixing position of the workpiece 31 to the machine tool 12 are closer than a predetermined default value, or when the workpiece 31 is positioned between the cutting position and the vibration measurement position. When the fixed position has a certain positional relationship, the vibration suppressed at the fixed position of the workpiece 31 is measured. For this reason, since the sensor 13 can measure only vibration smaller than the vibration of the workpiece 31 that is actually occurring, determination by comparison of the same fixed threshold value and vibration data cannot be used to determine the state of wear of the tool 124. Misjudgment may occur.

Therefore, the machining condition evaluation unit 22 evaluates the vibration based on the material properties of the work 31, the dynamic properties of the work 31, the shape information of the work 31, the fixed position of the work 31 on the processing table 125, the information on the vibration measurement position, and the like. Analytically calculate the vibration characteristics of the vibration of the machine tool 12 or the work 31 measured at the measurement position, and based on the calculated vibration characteristics, a cutting position suitable for determining the wear of the tool 124 can be determined in advance. . In this case, the machining condition evaluation unit 22 compares a predetermined cutting position suitable for determining wear of the tool 124 with the cutting position coordinates acquired at each time point during the cutting process, and calculates the machining condition determination result. , a region suitable for determining the state of wear of the tool 124 can be determined.

That is, the machining condition evaluation unit 22 calculates the machining condition determination result based on the vibration transmission characteristics between the fixed position of the workpiece 31 with respect to the machine tool 12 and the position where the vibration data is measured by the sensor 13, and A region suitable for determining the state of wear can be determined. In addition, the machining condition evaluation unit 22 determines the mechanical positional relationship between the cutting position at each time point during the cutting of the work 31, the measurement position of the vibration data by the sensor 13, and the fixed position of the work 31 with respect to the machine tool 12. A region suitable for determining the wear state of the tool 124 can be determined by calculating the machining condition determination result based on.

By determining the wear state of the tool based on the vibration data acquired in the region suitable for determination of the wear state of the tool 124 determined in this way, it is possible to determine the machining conditions that change as the cutting progresses. If at least one of the measured vibration amplitude and frequency changes due to the difference, it is possible to suppress erroneous determination of the wear state of the tool 124 .

In addition, instead of analytically calculating the vibration characteristics of the vibration of the machine tool 12 or the work 31 as described above, the machining condition evaluation unit 22 performs trial machining of the work 31 in the machine tool 12 in advance and obtains vibration data. , a suitable cutting position for determining the state of wear of the tool 124 may be determined. The machining condition evaluation unit 22 calculates, for example, a region of cutting position coordinates where the vibration characteristics can be considered to be temporally identical in the region to be processed of the workpiece 31 based on vibration data obtained by performing trial processing. Then, the calculated area may be determined as a cutting position suitable for determining the wear state of the tool 124 . That is, the cutting position coordinates included in the calculated area may be determined as the cutting position suitable for determining the wear state of the tool 124 .

That is, the machining condition evaluation unit 22 determines that the vibration data acquired by performing the trial machining is such that the time variation of the vibration data due to the variation of the cutting position during the cutting of the same workpiece 31 is equal to or less than a predetermined value. A position coordinate or a cutting position coordinate in which the time variation of the frequency spectrum of the vibration data is equal to or less than a predetermined value can be determined as a region suitable for determining the wear state of the tool 124 . Here, in the trial machining, a tool such as a new tool that is obviously not worn is used.

Therefore, the machining condition evaluation unit 22 can determine the machining condition determination result based on the time variation of the amplitude of the vibration data acquired in the trial machining performed in advance. Further, the machining condition evaluation unit 22 can determine the machining condition determination result based on the time variation of the frequency spectrum of the vibration data obtained in the trial machining performed in advance. By determining the wear state of the tool 124 based on the vibration data acquired in the region suitable for determining the wear state of the tool 124 determined in this way, the machining conditions that change as the cutting progresses When at least one of the amplitude and frequency of the measured vibration changes due to the difference in , it is possible to suppress erroneous determination of the wear state of the tool 124 .

Further, the machining condition evaluation unit 22 determines whether or not the cutting position at each time point during cutting of the workpiece 31 is suitable for determining the wear state of the tool 124, the cutting conditions obtained from the state quantity acquisition unit 21. Instead of using the position coordinates, the cutting position of the workpiece 31 corresponding to each time point during cutting of the workpiece 31 is estimated from the cutting time of the workpiece 31, and the machining condition determination result is obtained based on the estimated cutting position. can be configured to The cutting time of the workpiece 31 is the time after the cutting of the workpiece 31 is started.

In addition, the machining condition evaluation unit 22 compares, for example, cutting position information suitable for determining the wear state of the tool 124 given in advance with the cutting positions acquired at each time during the cutting of the workpiece 31. can be used to calculate the machining condition determination result. That is, the machining condition evaluation unit 22 determines whether the cutting position information suitable for determining the state of wear of the tool 124 given in advance and the cutting position coordinates acquired at each time point during the cutting of the workpiece 31 match each other. In this case, it can be determined that the cutting position coordinates at each time point during cutting of the workpiece 31 are suitable for determining the wear state of the tool 124 . By determining the wear state of the tool 124 based on the vibration data acquired in the region suitable for determining the wear state of the tool 124 determined in this way, the machining conditions that change with the progress of the cutting process can be adjusted. If at least one of the measured vibration amplitude and frequency changes due to the difference, it is possible to suppress erroneous determination of the wear state of the tool 124 .

A cutting position suitable for determining the wear state of the tool 124 given in advance is determined by using at least one of the cutting position, the cutting path, the vibration measurement position with respect to the cutting position, and the shape information of the work 31. can be obtained by analytically calculating the vibration characteristics of the vibration generated in

Information on cutting positions suitable for determining the state of wear given in advance is stored in the machining condition evaluation unit 22 . The information on the cutting position suitable for determining the state of wear given in advance may be stored in a component other than the machining condition evaluation unit 22 in the tool wear determination device 1. For example, the information may be stored in a storage unit (not shown). good.

Further, when calculating the vibration characteristics of the machine tool 12 or the work 31, further At least one of the information may be added.

Regarding the vibration characteristics analytically calculated as described above, the machining condition evaluation unit 22 determines the natural vibration frequency of the machine tool 12 to which the work 31 is fixed or the work 31 fixed to the machine tool 12 in the work 31, A region in which the frequency of the characteristic vibration indicating the wear of the tool 124 does not overlap is determined to be a region suitable for determining the wear state of the tool 124, and the characteristic vibration frequency and the characteristic indicating the wear state of the tool 124 It may be determined that a region in which a typical frequency overlaps with a region that is not suitable for determining the state of wear. By determining the wear state of the tool 124 based on the vibration data acquired in the region suitable for determining the wear state of the tool 124 determined in this way, the machining conditions that change with the progress of the cutting process can be adjusted. If at least one of the measured vibration amplitude and frequency changes due to the difference, it is possible to suppress erroneous determination of the wear state of the tool 124 .

As the shape information of the work 31 described above, not only the shape information of the work 31 before cutting but also the shape information of the work 31 during cutting which is estimated from the machining program for the work 31 at each point in time can be used. can also

FIG. 6 is a diagram showing another fixing method of the workpiece 31 according to Embodiment 1 of the present invention. Although FIG. 4 and FIG. 5 describe the case where the workpiece 31 is fastened and fixed to the processing table 125 with bolts, the method of fixing the workpiece 31 is not limited to this. For example, as shown in FIG. 6, the workpiece 31 may be fixed using a vise. Consider fixing the workpiece 31 by sandwiching the workpiece 31 between the fixing surface 33 of the vise fixed to the machining table 125 and another fixing surface (not shown) facing the fixing surface 33, and cutting the machining path c.

In this case, the area 34 of the workpiece 31 that is at a predetermined distance or more from any side, any surface, or any fixed surface of the workpiece 31 is suitable for determining the wear state of the tool 124. It can be thought of as a working area. That is, it can be considered that the portion of the machining path c that overlaps with the region 34 is suitable for determining the wear state of the tool 124 .

In this way, the tool wear determination device 1 suppresses erroneous determination of the wear state of the workpiece 31 fixed by an arbitrary method due to changes in the vibration characteristics determined based on the structure of the workpiece 31 and the machine tool. It is possible to achieve the effect of

FIG. 7 is a flow chart showing an example of processing by the machine tool 12 and the tool wear determination device 1 according to Embodiment 1 of the present invention. The processing of the tool wear determination device 1 is executed along with the cutting of the workpiece 31 by the machine tool 12 .

When the machining of the workpiece 31 by the machine tool 12 is started, the machine tool 12 cuts the workpiece 31 along the coordinate W at a certain time t(k) in step S110. For example, the machine tool 12 cuts the workpiece 31 at coordinates W(x(k), y(k), z(k)) at a certain time t(k).

In step S<b>120 , the state quantity acquisition unit 21 acquires the state quantity of the machine tool, including vibration data, which occurs as the workpiece 31 is cut. The state quantity acquisition unit 21 transmits the vibration data among the acquired state quantities of the machine tool to the vibration feature quantity calculation unit 23, and the state quantities of the machine tool other than the vibration data among the acquired state quantities of the machine tool are used as the machining conditions. Send to the evaluation unit 22 . Machining conditions indicated by state quantities of the machine tool other than the vibration data are machining conditions that change as the cutting progresses.

In step S130, the vibration feature amount calculator 23 analyzes the vibration data acquired from the state quantity acquisition unit 21 to calculate the vibration feature amount. The vibration feature amount calculation unit 23 transmits the calculated vibration feature amount to the wear state determination unit 24 .

In step S140, the machining condition evaluation unit 22 evaluates state quantities of the machine tool other than the vibration data, which are machining conditions that change as the cutting progresses. In step S150, the machining condition evaluation unit 22 determines, based on the state quantity of the machine tool acquired from the state quantity acquisition unit 21, the machining condition indicated by the state quantity of the machine tool for the tool 124 attached to the machine tool 12. It is determined whether or not the machining conditions are suitable for determining the state of wear. The machining condition evaluation unit 22 transmits the machining condition determination result, which is the determination result, to the wear state determination unit 24 .

If the machining condition evaluation unit 22 determines that the machining condition indicated by the state quantity of the machine tool is suitable for determining the wear condition of the tool 124 attached to the machine tool 12, Yes in step S150. Therefore, the process proceeds to step S160. If it is determined that the machining condition indicated by the state quantity of the machine tool is not suitable for determining the wear condition of the tool 124 attached to the machine tool 12, the result in step S150 is No, and the process proceeds to step S180.

In step S160, the wear condition determination unit 24 determines that the machining condition determination result obtained from the machining condition evaluation unit 22 is a machining condition that changes as the cutting progresses and is suitable for determining the wear condition of the tool 124. , it is determined whether or not the vibration feature quantity acquired from the vibration feature quantity calculation unit 23 is equal to or greater than a predetermined threshold value. If it is determined that the vibration feature amount is equal to or greater than the predetermined threshold value, the determination in step S160 is YES, and the worn state determination unit 24 displays display instruction information for instructing display of a message indicating that the tool 124 is in a worn state. It is transmitted to the device 14 and proceeds to step S170. If it is determined that the vibration feature amount is not equal to or greater than the predetermined threshold value, the determination in step S160 is No, and the process proceeds to step S180.

In step S<b>170 , the display device 14 displays a message indicating that the tool 124 is in a worn state based on the display instruction information received from the worn state determination section 24 .

In step S180, the machine tool 12 updates the coordinates for cutting the workpiece 31 to the coordinates at the next time, and returns to step S110. For example, the machine tool 12 updates the coordinates for cutting the workpiece 31 to the coordinates W(x(k+1), y(k+1), z(k+1)) at the next time t(k+1).

Note that the order of steps S130 and S140 may be interchanged.

As described above, the tool wear determination device 1 according to the first embodiment determines whether or not the machining conditions that change as the cutting progresses are suitable for determining the wear state of the tool 124. If the machining conditions that change accordingly are suitable for determining the wear state of the tool 124, it is determined whether the tool 124 is in the wear state based on the vibration feature amount. Therefore, the tool wear determination device 1 according to the first embodiment can determine the wear state of the tool 124 by suppressing erroneous determinations due to changes in the vibration characteristics of the workpiece as the cutting progresses. 124 has an effect of improving the accuracy of determination of the state of wear.

Embodiment 2.
FIG. 8 is a block diagram showing the configuration of a tool wear determination device 2 according to Embodiment 2 of the present invention. Below, the tool wear determination device 2 according to the second embodiment will be described, focusing on differences from the tool wear determination device 1 according to the first embodiment described above. A detailed description of the configuration similar to that of the first embodiment is omitted.

The tool wear determination device 2 according to the second embodiment further includes a storage unit 226 in addition to the configuration of the tool wear determination device 1, and has a configuration in which the wear state determination unit 24 is replaced with the wear state determination unit 224. .

The storage unit 226 stores processing conditions that change with the progress of cutting, the determination result of the processing condition evaluation unit 22 that is the determination result of the processing conditions that change with the progress of cutting, and the characteristics of the vibration feature amount calculation unit 23. The calculation result of the amount and the determination result of the wear state of the tool 124 in the wear state determination unit 224 can be temporally synchronized and stored as a determination history. That is, the storage unit 226 stores the determination result of the machining condition evaluation unit 22, the feature amount calculation result of the vibration feature amount calculation unit 23, and the wear state determination unit 224, which are processed at each point during cutting of the workpiece 31. The determination result of the wear state of the tool 124 is temporally associated and stored as a determination history at each point in time during cutting of the workpiece 31 .

If the machining condition evaluation unit 22 determines that the machining conditions that change as the cutting progresses are suitable for determining the wear condition of the tool 124, the wear condition determination unit 224 Similarly, the wear state of the tool 124 is determined based on the vibration feature amount calculated by the vibration feature amount calculator 23 .

The wear state determination unit 224 determines the wear state of the tool 124 by comparing the vibration feature amount calculated by the vibration feature amount calculation unit 23 and the determination history stored in the storage unit 226 . For example, the wear state determination unit 224 extracts determination histories indicating that the tool is not in a worn state, that is, the tool is in a normal state, from a plurality of determination histories stored in the storage unit 226 .

In other words, the wear state determination unit 224 extracts the determination history in which the tool is determined to be in a normal state, and calculates the frequency distribution or the statistic for the vibration feature quantity included in the extracted determination history. Then, the frequency distribution or statistic of the calculated vibration feature amount is compared with the vibration feature amount calculated by the vibration feature amount calculation unit 23, and the vibration feature amount calculated by the vibration feature amount calculation unit 23 is the vibration feature amount. The wear state determination unit 224 can be configured to determine that the tool 124 is in a wear state when it has a statistically predetermined significant difference with respect to the frequency distribution or the statistic of the quantity. As a result, the tool wear determination device 2 does not require the wear state determination unit 224 to predetermine the threshold value to be compared with the vibration feature amount to determine the wear state of the tool 124, and the tool wear determination device 1 of the first embodiment. A similar effect can be obtained.

Further, for example, the wear state determination unit 224 extracts, from the determination history, a determination history in which the tool is determined to be in a normal state and matches the machining conditions acquired by the machining condition evaluation unit 22, and is included in the extracted determination history. A frequency distribution or a statistic may be calculated for the vibration feature amount. Then, the frequency distribution or statistic of the calculated vibration feature amount is compared with the vibration feature amount calculated by the vibration feature amount calculation unit 23, and the vibration feature amount calculated by the vibration feature amount calculation unit 23 is the vibration feature amount. It can be configured to determine that the tool 124 is in a worn state if it has a statistically predetermined significant difference from the frequency distribution or statistic for the quantity. In this case, the storage unit 226 stores the determination result in the processing condition evaluation unit 22 and the processing conditions that change as the cutting progresses in the determination history.

As a result, the tool wear determination device 2 extracts the determination history that matches the machining conditions acquired by the machining condition evaluation unit 22 , thereby determining the wear of the tool 124 corresponding to the machining conditions that change during the cutting of the workpiece 31 . A state determination result is obtained.

Further, the wear state determination unit 224 is configured to determine that the tool 124 is in a normal state within a predetermined period after the tool 124 is replaced with a new tool. good too.

By configuring the wear state determination unit 224 in this way, the determination history obtained within a predetermined period after the tool 124 is replaced with a new one is stored in the storage unit 226 as the determination history in the normal state. be. The predetermined period can be determined, for example, by cumulative cutting time or cumulative cutting distance.

FIG. 9 is a flow chart showing an example of processing by the machine tool 12 and the tool wear determination device 2 according to Embodiment 2 of the present invention. The difference between the flowchart shown in FIG. 9 and the flowchart shown in FIG. 7 is that steps S210 and S230 are newly provided, and step S160 is replaced with step S220.

In step S<b>210 , the wear state determination unit 224 extracts from the storage unit 226 the determination history of the tool being determined to be in a normal state.

In step S220, the wear state determination unit 224 compares the frequency distribution or statistics of the vibration feature amount included in the extracted determination history with the vibration feature amount calculated by the vibration feature amount calculation unit 23, and determines the vibration feature amount. It is determined whether or not the vibration feature amount calculated by the amount calculation unit 23 has a statistically predetermined significant difference from the frequency distribution or the statistic of the vibration feature amount. If it is determined that there is a significant difference, the tool 124 is in a worn state, the result of step S220 is Yes, and the process proceeds to step S170. If it is determined that there is no significant difference, the tool 124 is in a normal state, the result of step S220 is No, and the process proceeds to step S230.

In the case of No in step S220, in step S230, the storage unit 226 stores the processing conditions that change as the cutting progresses, and the processing conditions that change as the cutting progresses. The determination result, the calculation result of the feature amount in the vibration feature amount calculation unit 23, and the determination result of the wear state of the tool 124 in the wear state determination unit 224 are acquired, and these pieces of information are temporally synchronized so that the tool is in a normal state. is stored as the determination history.

If No in step S150, the process proceeds to step S230. In this case, in step S230, the judgment results of the machining condition evaluation section 22, which are the judgment results of the machining conditions that change as the cutting progresses, are stored as the judgment history.

In the above process, the storage unit 226 stores the history of the vibration feature amounts when the wear state determination unit 24 determines that the tool 124 is in a normal state. Then, the wear state determination unit 224 determines the wear state of the tool 124 based on the vibration feature amount newly acquired during cutting of the workpiece 31 and the history vibration feature amount stored in the storage unit 226 .

The tool wear determination device 2 according to the second embodiment performs the above-described processing to determine in advance the threshold value to be compared with the vibration feature amount in order to determine the wear state of the tool 124 in the wear state determination unit 224. However, it is possible to obtain the same effect as the tool wear determination device 1 of the first embodiment.

Further, in step S<b>210 , the wear state determination unit 224 may extract a determination history in which the tool is determined to be in a normal state and matches the machining conditions acquired by the machining condition evaluation unit 22 from the determination history. Then, in step S220, the wear state determination unit 224 calculates a frequency distribution or a statistic for the vibration feature quantity included in the extracted determination history. Then, the frequency distribution or statistic of the calculated vibration feature amount is compared with the vibration feature amount calculated by the vibration feature amount calculation unit 23, and the vibration feature amount calculated by the vibration feature amount calculation unit 23 is the vibration feature amount. The tool is determined to be in a worn state when it has a statistically predetermined significant difference from the frequency distribution or statistics of the quantity.

In the above process, when the wear state determination unit 24 determines that the tool 124 is in a normal state, the state quantity of the machine tool other than the vibration data acquired by the state quantity acquisition unit 21 and the vibration feature value calculation unit 23 The storage unit 226 stores a history associated with the calculated vibration feature amount. Then, the wear state determination unit 224 retrieves the history stored in the storage unit 226 based on the state quantity of the machine tool other than the vibration data newly acquired by the state quantity acquisition unit 21 when cutting the workpiece 31. Then, the wear state of the tool 124 is determined based on the vibration feature amount obtained by the vibration feature amount calculation unit 23 during cutting of the workpiece 31 and the extracted history vibration feature amount.

The tool wear determination device 2 according to the second embodiment stores information that can be used for determination by the wear state determination unit 224 in the storage unit 226, and performs the above-described processing, so that the wear state determination unit 224 has a tool It is possible to obtain the same effect as the tool wear determination device 1 of the first embodiment without predetermining a threshold value to be compared with the vibration feature amount in order to determine the wear state of 124 .

FIG. 10 is a flow chart showing an example of another process performed by the machine tool 12 and the tool wear determination device 2 according to Embodiment 2 of the present invention. 10, in the tool wear determination device 2 according to the second embodiment, information indicating that the tool 124 is in a normal state within a predetermined period after the tool 124 is replaced with a new one is stored in the storage unit 226. An example of processing in the case of The difference between the flowchart shown in FIG. 10 and the flowchart shown in FIG. 9 is that step S240 and step S250 are newly provided and step S230 is deleted.

In step S240, the wear state determination unit 224 determines whether or not a predetermined period has passed since the tool 124 was replaced with a new one. If the predetermined time period has not been exceeded, that is, if it is within the predetermined time period, the determination in step S240 is No, and the process proceeds to step S250. If the predetermined time period has been exceeded, the determination in step S240 is Yes, and the process proceeds to step S210. Information on when the tool 124 has been replaced with a new one is given to the wear state determining section 224 in advance. The wear state determination unit 224 may be configured to acquire information on when the tool 124 was replaced with a new one from the numerical control device 11, or may be configured to acquire information from an external device of the tool wear determination device 2 other than the numerical control device 11. may be

In step S250, the storage unit 226 stores the machining conditions that change as the cutting progresses, the judgment results of the machining condition evaluation unit 22 that are the judgment results of the machining conditions that change as the cutting progresses, and the vibration feature quantity. , and the determination result that the tool 124 is in a normal state are temporally synchronized and stored as a determination history, and the process proceeds to step S180. In other words, the storage unit 226 stores the history of determination that the tool is normal.

In the tool wear determination device 2 according to the second embodiment, by performing the above-described processing, the wear state determination unit 224 determines in advance the threshold value to be compared with the vibration feature amount to determine the wear state of the tool 124. However, it is possible to obtain the same effect as the tool wear determination device 1 of the first embodiment.

Embodiment 3.
FIG. 11 is a block diagram showing the configuration of a tool wear determination device 3 according to Embodiment 3 of the present invention. Below, the tool wear determination device 3 according to the third embodiment will be described, focusing on differences from the tool wear determination device 2 according to the second embodiment described above. Detailed descriptions of the configurations similar to those of the first and second embodiments are omitted.

In the tool wear determination device 3 according to the third embodiment, the storage unit 226 is replaced with a storage unit 326 in the configuration of the tool wear determination device 2, and a communication unit 327 is newly provided. It has a configuration that enables communication with a server device 328 arranged outside.

In addition to the function of the storage unit 226 of the tool wear determination device 2 , the storage unit 326 receives and stores a part or all of the data of the determination history held by the server device 328 via the communication unit 327 . The storage unit 326 also transmits part or all of the data of the determination history stored in the storage unit 326 to the server device 328 via the communication unit 327 .

The communication unit 327 can transmit and receive information to and from the storage unit 326 . Further, the communication unit 327 is connected to the network 329 and is capable of transmitting and receiving information to and from the server device 328 , and is capable of transmitting and receiving determination histories to and from the server device 328 . As a result, the tool wear determination device 3 can exchange information with the server device 328 via the network 329 .

The server device 328 is a server device capable of exchanging information with the communication unit 327 via the network 329 . The server device 328 receives and stores part or all of the determination history data stored in the storage unit 326 . The server device 328 also transmits part or all of the stored determination history data to the storage unit 326 . The server device 328 has a larger storage capacity than the storage unit 326 and can store more data than the storage unit 326 . The server device 328 is not particularly limited, and may be an external storage device external to the tool wear determination device 3 that can copy and store the determination history stored in the storage unit 326. It may be a tool wear determination device or a data server such as a cloud.

FIG. 12 is a flow chart showing an example of processing by the machine tool 12 and the tool wear determination device 3 according to Embodiment 3 of the present invention. The difference between the flowchart shown in FIG. 12 and the flowchart shown in FIG. 9 is that step S310 and step S320 are newly provided.

In step S<b>310 , the storage unit 326 copies the determination history held by the server device 328 . That is, the storage unit 326 receives and stores part or all of the data of the determination history held by the server device 328 via the communication unit 327 .

In step S<b>320 , the wear state determination unit 224 copies the determination history stored in the storage unit 326 to the server device 218 . That is, the wear state determination unit 224 transmits a part or all of the data of the determination history stored in the storage unit 326 through the communication unit 327 and stores the data in the server device 328 . Note that the timing at which step S320 is performed is not limited, and may be performed at any timing.

The tool wear determination device 3 according to the third embodiment can obtain the same effect as the tool wear determination device 2 according to the second embodiment by performing the processing described above.

In addition, the tool wear determination device 3 can store a large number of determination histories in the storage unit 326, and the accuracy of determination of the wear state corresponding to the machining conditions that change during cutting of the workpiece 31 can be improved. is obtained.

In addition, since the tool wear determination device 3 can store the determination history in the server device 328, even if the storage unit 326 or the tool wear determination device 3 is initialized or replaced, the past determination history can be used for tool wear determination. It can be left outside the device 3 . Thereby, even when the storage unit 326 or the tool wear determination device 3 is initialized or replaced, it is possible to utilize the past determination history.

The configuration shown in the above embodiment shows an example of the contents of the present invention, and it is possible to combine the techniques of the embodiments with each other or with another known technique. However, part of the configuration may be omitted or changed without departing from the gist of the present invention.

1, 2, 3 tool wear determination device, 11 numerical control device, 12 machine tool, 13 sensor, 14 display device, 21 state quantity acquisition unit, 22 machining condition evaluation unit, 23 vibration feature amount calculation unit, 24 wear state determination unit , 31 workpiece, 31a one end, 31b other end, 31c side surface, 31d groove, 31s1 one side, 31s2 other side, 32a, 32b, 32c, 32d fixed part, 33 fixed surface, 34 area, 101 processor, 102 memory, 121 body part , 122 spindle head, 123 spindle, 124 tool, 125 machining table, 224 wear state determination unit, 226, 326 storage unit, 327 communication unit, 328 server device, 329 network, a, b, c machining path, a1, a2, a3, a4, a5 minor paths.

Claims (12)

A tool wear determination device for determining the wear state of a tool for cutting a workpiece in a machine tool,
a state quantity acquisition unit that acquires a state quantity of the machine tool including vibration data representing vibration generated in the machine tool or the work when the work is cut by the machine tool;
a machining condition evaluation unit that determines whether machining conditions indicated by the state quantities of the machine tool other than the vibration data acquired by the state quantity acquisition unit are suitable for determining the wear state of the tool; ,
a vibration feature quantity calculation unit that calculates a vibration feature quantity representing a feature of vibration generated in the machine tool or the workpiece based on the vibration data;
If the machining condition determination result, which is the determination result of the machining condition evaluation unit, is a determination result that is suitable for determining the wear state of the tool, whether the tool is in the wear state based on the vibration feature amount A wear state determination unit that determines whether or not
with
The processing condition evaluation unit
analytically calculating the vibration characteristics of the machine tool or the workpiece based on the state quantities of the machine tool other than the vibration data, and calculating the state of the machine tool other than the vibration data based on the calculated vibration characteristics; For a plurality of different machining conditions indicated by the quantity, it is determined in advance whether the machining conditions are suitable for determining the wear state of the tool, and the machining is suitable for determining the wear state of the tool with the plurality of different machining conditions. Pre-store information indicating the relationship with the determination result of whether or not it is a condition,
Based on the information indicating the relationship, whether or not the machining condition indicated by the state quantity of the machine tool other than the vibration data acquired by the state quantity acquisition unit is suitable for determining the wear state of the tool. determining whether
A tool wear determination device characterized by: The machining condition evaluation unit evaluates the machining condition based on at least one of material characteristics of the workpiece, dynamic characteristics of the workpiece, and shape of the workpiece at each time point during cutting of the workpiece. estimating the vibration characteristics of the machine or the work in advance, and calculating the machining condition determination result based on the vibration characteristics of the machine tool or the work estimated for each time point during cutting of the work;
The tool wear determination device according to claim 1, characterized by: The machining condition evaluation unit analytically uses one or more of a cutting position at each time point during cutting of the workpiece, a cutting path in the cutting of the workpiece, and a measurement position of the vibration data with respect to the cutting position. calculating the processing condition determination result based on the vibration characteristic calculated in
The tool wear determination device according to claim 2, characterized by: The machining condition evaluation unit calculates the machining condition determination result based on the distance between the cutting position at each time point during cutting of the workpiece and the end of the workpiece;
The tool wear determination device according to claim 2, characterized by: The machining condition evaluation unit calculates the machining condition determination result based on a distance between a cutting position at each time point during cutting of the workpiece and a fixed position of the workpiece with respect to the machine tool;
The tool wear determination device according to claim 2, characterized by: The machining condition evaluation unit calculates the machining condition determination result based on a positional relationship between a fixed position of the workpiece with respect to the machine tool and a measurement position of the vibration data;
The tool wear determination device according to claim 2, characterized by: The machining condition evaluation unit determines the machining condition based on the positional relationship between the cutting position at each time point during cutting of the workpiece, the measurement position of the vibration data, and the fixed position of the workpiece with respect to the machine tool. calculating a result;
The tool wear determination device according to claim 2, characterized by: A storage unit that stores a history of the vibration feature amount when the wear state determination unit determines that the tool is in a normal state,
The wear state determination unit determines the wear state of the tool based on the vibration feature value acquired during cutting of the workpiece and the vibration feature value stored in the storage unit;
The tool wear determination device according to any one of claims 1 to 7 , characterized by: State quantities of the machine tool other than the vibration data acquired by the state quantity acquisition unit when the wear state determination unit determines that the tool is in a normal state, and calculated by the vibration feature value calculation unit A storage unit that stores a history associated with the vibration feature amount,
The wear state determination unit extracts the history stored in the storage unit based on the state quantity of the machine tool other than the vibration data acquired by the state quantity acquisition unit during cutting of the workpiece. Determining the wear state of the tool based on the vibration feature amount acquired by the vibration feature amount calculation unit during cutting of the workpiece and the vibration feature amount of the extracted history,
The tool wear determination device according to any one of claims 1 to 7 , characterized by: Equipped with a communication unit capable of communicating with an external storage device,
The storage unit receives and stores information stored in an external storage device via the communication unit;
The tool wear determination device according to claim 8 or 9 , characterized by: The information stored in the storage unit can be transmitted to an external storage device via the communication unit;
The tool wear determination device according to claim 10 , characterized by: The state quantity acquisition unit acquires the state quantity of the machine tool from a sensor attached to the machine tool or the workpiece, or from a numerical control device connected to the machine tool;
The tool wear determination device according to any one of claims 1 to 11 , characterized by:

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