JP6920092B2 - Drilling system, drill abnormality detection method and manufacturing method of the product to be drilled - Google Patents

Description

Embodiments of the present invention relate to a drilling system, a drill abnormality detection method, and a method for manufacturing a product to be drilled.

In machining using a drilling machine or a machine tool, it is important to detect wear or loss of the tool. Therefore, conventionally, various methods for detecting abnormalities in tools have been proposed (see, for example, Patent Documents 1 to 5). For example, as an electric drilling machine, a machine having a function of detecting an abnormality of a drill by monitoring fluctuations in electric power and torque is commercially available.

On the other hand, the drilling work is shifting from manual work by a worker using a hand-held drill drive device to machining by an automatic drilling machine (see, for example, Patent Document 6).

Japanese Unexamined Patent Publication No. 11-309649 Jikkenhei 06-027051 Jikkenhei 02-117850 Japanese Unexamined Patent Publication No. 61-274848 Jitsukaisho 60-022252 Japanese Unexamined Patent Publication No. 2016-175157

When perforation is automatically performed by an automatic perforation machine, it is not possible to detect missing or worn drills by the sense or visual inspection of the operator's hand, unlike the case where perforation is performed manually. If drilling is performed using a drill that has an abnormality such as a chip or wear, it will lead to the occurrence of a defect. Therefore, when the automatic drilling machine automatically drills, it is desired to be able to automatically detect not only the drilling but also the abnormality of the drill.

However, in the case of a non-electric automatic drilling machine such as an air-driven automatic drilling machine, fluctuations in electric power and torque cannot always be easily monitored. On the other hand, when a machine tool such as a machining center or a drilling machine is provided with a drill abnormality detection function, it is necessary to determine the specifications from the design stage of the machine tool. In other words, it is desired that not only machine tools but also automatic drilling machines other than machine tools can easily add a tool abnormality detection function later. It is also useful to enable the anomaly detection function system to operate without using the drive source of the perforator, regardless of whether or not the tool anomaly detection function is subsequently added to the perforator.

Therefore, an object of the present invention is to enable automatic detection of an abnormality in a drill regardless of the type of drilling machine.

The drilling system according to the embodiment of the present invention includes a drill abnormality detection system, a drilling machine for rotationally driving a drill, an integrated circuit tag, and a reader . The drill abnormality detection system includes a vibration sensor and a signal processing system. The vibration sensor is attached to the drilling machine, the drilling target by the drill, or the drilling plate attached to the drilling target, and directly or indirectly detects the vibration of the drill during rotation. The signal processing system performs the drill by comparing the waveform of the detection signal indicating the vibration of the drill detected by the vibration sensor with the reference waveform corresponding to the case where there is no abnormality in the drilling using the drill. Monitor anomalies in the drilling used. The integrated circuit tag is attached to at least one of the perforation target and the perforation plate, and information for specifying a threshold value for an index value representing the amount of deviation of the waveform of the detection signal from the reference waveform is recorded. The reader is attached to the perforator side, reads the information recorded in the integrated circuit tag, and transfers the information to the signal processing system. The signal processing system identifies the threshold value based on the transferred information, and determines that an abnormality has occurred in the drilling using the drill when the index value is equal to or higher than the threshold value or exceeds the threshold value. It is composed of.

Further, the drill abnormality detection method according to the embodiment of the present invention uses a drilling machine for rotationally driving the drill, a drilling target by the drill, or a vibration sensor attached to a drilling plate attached to the drilling target during rotation. The step of directly or indirectly detecting the vibration of the drill is compared with the waveform of the detection signal representing the vibration of the drill detected by the vibration sensor and the reference waveform corresponding to the case where there is no abnormality in the drill. possess and monitoring the abnormality of the perforation with the drill by, the waveform of the detection signal, and records information for specifying a threshold for the index value representing the amount of deviation from the reference waveform integrated The circuit tag is attached to at least one of the perforation target and the perforation plate, and the information recorded in the integrated circuit tag is read and transferred by a reader attached to the perforator side, and based on the transferred information. The threshold value is specified, and when the index value is equal to or higher than the threshold value or exceeds the threshold value, it is determined that an abnormality has occurred in the drilling using the drill .

Further, in the method for manufacturing a product to be drilled according to the embodiment of the present invention, a step of monitoring an abnormality in drilling using a drill during rotation by the above-mentioned drill abnormality detection method and a rotary drive of the drill by the drilling machine are performed. It has a step of manufacturing the product to be drilled by drilling the punched object.

The functional block diagram which shows the structure of the drilling system provided with the drill abnormality detection system which concerns on embodiment of this invention. The front view which shows the structural example of the drilling system shown in FIG. Top view of the drilling system shown in FIG. The left side view which shows the structural example of the 1st traveling mechanism provided in the drilling system shown in FIG. The right side view which shows the structural example of the 2nd traveling mechanism provided in the drilling system shown in FIG. The view which looked at the perforation plate shown in FIG. 2 from the right direction. The graph which shows the example which the rotation speed decreased by the loss of a drill. The graph which shows the example which compared the frequency spectrum obtained by applying the fast Fourier transform (FFT) to the acceleration signal which shows the vibration level of a drill. FIG. 5 is a flowchart showing an example of a flow in a case where a workpiece is drilled with an abnormality monitoring of drilling using a drill by a drilling system provided with a drill abnormality detection system shown in FIG.

The drilling system, the drill abnormality detection method, and the manufacturing method of the product to be drilled according to the embodiment of the present invention will be described with reference to the accompanying drawings.

(Configuration and function of drilling system equipped with drill abnormality detection system)
FIG. 1 is a functional block diagram showing a configuration of a drilling system provided with a drill abnormality detection system according to an embodiment of the present invention, FIG. 2 is a front view showing a configuration example of the drilling system shown in FIG. 1, and FIG. 3 is shown in FIG. Top view of the drilling system shown, FIG. 4 is a left side view showing a structural example of the first traveling mechanism provided in the drilling system shown in FIG. 2, and FIG. 5 is a second traveling mechanism provided in the drilling system shown in FIG. It is a right side view which shows the structural example of.

The drilling system 1 is a system that automatically drills the work W to be drilled by machining. In particular, the drilling system 1 has a function of detecting whether or not an abnormality such as a defect or wear or an abnormality such as a displacement of the drill from the prepared hole has occurred in the drill during drilling of the work W. That is, the drilling system 1 is a system capable of drilling the work W while monitoring the abnormality of the drill itself and the abnormality of drilling using the drill.

Therefore, the drilling system 1 includes a drilling machine 2 and a drill abnormality detection system 3. The drilling machine 2 can be composed of a punching machine main body 4 that actually holds a drill and punches the work W, and a control device 7 that controls the drilling machine main body 4. On the other hand, the drill abnormality detection system 3 is a system for monitoring the abnormality of the drill and the drilling during the drilling of the work W and detecting whether or not the abnormality has occurred in the drilling using the drill.

The drilling machine main body 4 is at least a device for rotationally driving the drill. Therefore, the drilling machine main body 4 includes a drill head 5 having a built-in rotation drive mechanism for holding and rotating the drill. The drilling machine main body 4 may be provided with an automatic feeding mechanism for performing a feeding operation in the tool axis direction of the drill, if necessary.

In the illustrated example, the drilling machine body 4 is provided with two drill heads 5 so that holes having two different diameters can be drilled. Each drill head 5 has a built-in air-type rotary drive mechanism for rotating the drill and an air-type automatic feed mechanism for performing a feed operation in the tool axis direction of the drill.

Further, the drilling machine main body 4 can be provided with a feed mechanism 6 for moving each drill head 5 itself in the tool axis direction of the drill. In the illustrated example, the feed mechanism 6 is configured with a rack and pinion 6A and a motor 6B for rotating the pinion side of the rack and pinion 6A. The rack is a straight rod with a gear cut, and the pinion is a circular gear with a small diameter that meshes with the rack.

Further, the drilling machine main body 4 can be, for example, a self-propelled device capable of traveling in the traveling area by the traveling mechanism 8. In the illustrated example, the work W is a structure in which a plurality of long structures W2 are provided on the plate-shaped part W1. Then, the punching machine main body is such that the first and second traveling mechanisms 8A and 8B of the crawler (track) type composed of a large number of rollers and chains travel on the upper surfaces of the two adjacent long structures W2. 4 is set.

The long structure W2 has a structure having a web and a flange. A plurality of positions of the long structure W2 on the web are drilling positions. Therefore, each tool axis direction of the drill is substantially the plate thickness direction of the web constituting the long structure W2 so that the web forming the long structure W2 can be drilled with the drill. The drilling machine main body 4 including the drill head 5 is arranged.

Each drive mechanism such as the rotary drive mechanism, the feed mechanism, and the traveling mechanism 8 of the drill provided in the drilling machine main body 4 is not limited to the illustrated example, and may be an air type, an electric type, or a hydraulic type. good.

A perforated plate 9 can be attached to the work W as needed. In the illustrated example as well, a plate-shaped perforated plate 9 is attached to the perforated side of the web by a tightening tool such as a bolt along the longitudinal direction of the long structure W2.

FIG. 6 is a view of the perforated plate 9 shown in FIG. 2 as viewed from the right.

As shown in FIG. 6, an arbitrary number of perforated plates 9 can be fixed to the work W with a tightening tool such as a bolt according to the shape of the work W. In the illustrated example, two perforated plates 9 are provided side by side. Each perforated plate 9 is provided with a through hole for a guide according to the perforated position of the work W, and an integrated circuit (IC: Integrated Circuit) tag 10 can be attached to each perforated plate 9.

In the illustrated example, since the punching machine main body 4 is configured to be able to reciprocate on the long structure W2 by the traveling mechanism 8, the IC tag 10 for the outbound route of the punching machine main body 4 and the punching machine main body 4 The IC tag 10 for the return route is attached to each perforated plate 9. The IC tag 10 can record desired information necessary for drilling, such as identification information (ID information) of each drilling plate 9 and selection information of the drill head 5 used for drilling.

If there are no restrictions on the work W, the IC tag 10 may be directly attached to the work W instead of the perforated plate 9. On the contrary, if the perforated plate 9 is attached to the work W and the IC tag 10 is attached to the perforated plate 9, the IC tag 10 is attached even if it is difficult to directly attach the IC tag 10 to the work W. Can be placed in the desired position.

When the IC tag 10 is attached to at least one of the work W and the drilling plate 9, the IC tag reader 11 for reading the information recorded on the IC tag 10 can be attached to the punching machine main body 4 side. Thereby, the IC tag 10 attached to the work W or the perforation plate 9 can perform automatic control including automatic traveling and automatic perforation of the perforator main body 4 using RFID (radio frequency identification indexifier) technology. RFID is a technique for wirelessly acquiring ID information from an RF tag such as an IC tag that records ID information.

The IC tag reader 11 has a function of reading the information recorded on the IC tag 10 and transferring the information to the control device 7 of the punching machine main body 4. On the other hand, the control device 7 has a function of controlling the punching machine main body 4 by outputting a control signal to the punching machine main body 4. That is, the control device 7 is a device that controls the drive of the drill head 5, the drive of the feed mechanism 6, the travel of the travel mechanism 8, and the like. Then, when the information recorded in the IC tag 10 is transferred from the IC tag reader 11 to the control device 7, the control device 7 controls the punching machine main body 4 based on the information transferred from the IC tag reader 11. It is composed of.

When the punching machine main body 4 travels by the traveling mechanism 8, it is desirable to reduce the weight of the punching machine main body 4. Therefore, a part of the control device 7 can be arranged outside the traveling area of the punching machine main body 4 without mounting the entire control device 7 on the punching machine main body 4. That is, the main part of the control device 7, which does not necessarily have to be mounted on the punching machine main body 4, can be installed outside the traveling area of the punching machine main body 4.

Therefore, the control device 7 can be composed of a main body portion 7A installed outside the traveling area and a control signal receiving device 7B mounted on the punching machine main body 4. Then, the punching machine main body 4 can be remotely controlled by transmitting the control signal from the main body 7A to the control signal receiving device 7B on the punching machine main body 4 side.

It is also possible to connect the main body 7A and the control signal receiving device 7B with a signal cable for transmitting a control signal. However, when the punching machine main body 4 travels by the traveling mechanism 8, it is possible to wirelessly transmit the control signal from the main body 7A to the control signal receiving device 7B by eliminating the need for a signal cable. It is desirable from the viewpoint of ensuring the degree of freedom of movement of the main body 4.

Therefore, the main body 7A of the control device 7 can be composed of the storage device 7C, the control signal generation unit 7D, and the radio 7E. The storage device 7C and the control signal generation unit 7D can be configured by an electronic circuit such as a computer into which a program is read.

The storage device 7C can store information referred to for generating a control signal of the punching machine main body 4. As a specific example, the ID information of each perforated plate 9 and the information indicating the relationship between the perforated positions can be stored in the storage device 7C. Then, when the IC tag 10 is attached to the perforated plate 9, if the ID information of the perforated plate 9 is recorded in the IC tag 10, the ID information of the perforated plate 9 is not recorded in the IC tag 10 itself. It is possible to specify the drilling position based on.

As a simple embodiment, when drilling a plurality of holes having a specific diameter arranged in a straight line as shown, the drilling position is one-dimensional position information, that is, the pitch between adjacent holes or It can be expressed as the distance from the reference position to each hole. Therefore, if a table showing the relationship between the ID information of the drilling plate 9 and the one-dimensional drilling position is stored in the storage device 7C, the drilling position can be specified based on the ID information of the drilling plate 9. ..

The control signal generation unit 7D generates each control signal of the drilling machine main body 4 for driving the drill head 5, driving the feed mechanism 6, traveling the traveling mechanism 8, and the like, and each generated control signal is used as the radio 7E. It has a function of transmitting to the control signal receiving device 7B wirelessly via. When generating the control signal, the information stored in the storage device 7C can be referred to.

As a specific example, if the storage device 7C stores the ID information of each perforated plate 9 and the information indicating the relationship between the perforated plate 9 and the perforated position, the control signal generation unit 7D is based on the ID information of the perforated plate 9. The drilling position can be specified, and the control signal of the punching machine main body 4 can be generated so that the drilling is performed at the specified drilling position. In this case, if the ID information of the perforated plate 9 is recorded in the IC tag 10, the control signal generation unit 7D can acquire the ID information of the perforated plate 9 from the IC tag reader 11. On the contrary, when the ID information of the perforated plate 9 is not recorded in the IC tag 10 or when the IC tag 10 is not used, the operator controls the ID information of the perforated plate 9 by operating the input device 7D. You may also enter in.

Of course, the control program of the punching machine main body 4 can be stored in the storage device 7C, and the punching machine main body 4 can be controlled without using the IC tag 10. Alternatively, the IC tag 10 may be attached to the work W or the drilling plate 9, and the control program of the punching machine main body 4 may be stored in the IC tag 10. In this case, the control program of the punching machine main body 4 stored in the IC tag 10 can be transferred to the control signal generation unit 7D by the IC tag reader 11.

On the other hand, the control signal receiving device 7B provided on the punching machine main body 4 side has a function of receiving each control signal of the punching machine main body 4 wirelessly transmitted from the main body 7A and outputting to the target device. That is, the components of the drilling machine main body 4 such as the drill head 5, the feeding mechanism 6, and the traveling mechanism 8 can be configured to be driven according to the control signal output from the control signal receiving device 7B. As a result, the desired operation of the drilling machine main body 4 can be remotely controlled wirelessly.

When the drilling machine main body 4 includes a component driven by an air signal or a hydraulic signal, a signal circuit that converts a control signal from an electric signal to a signal other than an electric signal such as an air signal or a hydraulic signal is provided. It is provided in the punching machine main body 4. Then, the necessary control signal is output to each component of the drilling machine main body 4.

When wireless communication is performed between the main body 7A of the control device 7 and the control signal receiving device 7B, it is possible to perform wireless communication between the IC tag reader 11 and the main body 7A of the control device 7 using a signal cable. It is desirable from the viewpoint of making it unnecessary. Therefore, the IC tag reader 11 can also be configured to read the information recorded in the IC tag 10 and wirelessly transfer the information to the main body 7A of the control device 7. In that case, the IC tag reader 11 is also provided with the radio 11A.

On the other hand, the drill abnormality detection system 3 is a system for detecting abnormalities such as chipping and wear of the drill held by each drill head 5 of the drilling machine main body 4 and abnormalities such as misalignment from the prepared hole of the drill. .. The drill abnormality detection system 3 can be configured by using the vibration sensor 12, the rotation speed sensor 13, the signal processing system 14, the radio 15, the input device 16, and the display device 17. One of the vibration sensor 12 and the rotation speed sensor 13 may be omitted depending on the abnormality detection target.

The vibration sensor 12 is a sensor that directly or indirectly detects the vibration of the drill during rotation. As the vibration sensor 12, a commercially available acceleration sensor or the like can be used. The vibration sensor 12 can be attached to the drilling machine main body 4, the work W, or the drilling plate 9 attached to the work W.

If the number of drilling plates 9 is small and the number of drilling machine main body 4 and drill head 5 is large, the number of required vibration sensors 12 can be reduced by attaching the vibration sensor 12 to the drilling plate 9. Can be done. That is, the common vibration sensor 12 can detect the vibration of the drills attached to the plurality of drilling machine main bodies 4 or the plurality of drill heads 5. Further, if the vibration sensor 12 is attached to the work W or the drilling plate 9, the vibration sensor 12 can be attached without disassembling or stopping the punching machine main body 4.

On the contrary, when the number of the drilling plates 9 is large and the number of the drilling machine main body 4 and the drill head 5 is small, the required number of vibration sensors 12 can be reduced by attaching the vibration sensor 12 to the punching machine main body 4 side. Can be reduced.

It is appropriate to mount the vibration sensor 12 at a position where the vibration of the drill can be detected well. The position where the vibration of the drill can be detected well does not make it difficult to detect the vibration of the drill because the vibration of the drill propagates without being attenuated and the vibration from other moving mechanical elements is superimposed. The position. In the illustrated example, the vibration sensor 12 is attached to the casing 5A of each drill head 5 incorporating the rotation drive mechanism and the feed mechanism of the drill.

The rotation speed sensor 13 is a sensor that detects the rotation speed of the drill during rotation. As the rotation speed sensor 13, either a contact type sensor that contacts the rotation speed detection target or a non-contact type sensor that does not contact the rotation speed detection target may be used. As the non-contact type rotation speed sensor 13, there is known a non-contact type rotation speed sensor 13 that detects the rotation speed of the rotating body by irradiating the rotating body with a laser beam and detecting the reflected light of the laser light. In the illustrated example, a non-contact rotation speed sensor 13 capable of detecting the rotation speed of the rotation shaft 5B rotating together with the drill is provided in the casing 5A of each drill head 5. That is, the rotation speed sensor 13 is arranged in a non-contact manner in the vicinity of the exposed portion of the rotation shaft 5B that rotates with the drill.

The signal processing system 14 can be composed of circuits such as a computer into which a program is read and an A / D (analog-to-digital) converter. When the punching machine main body 4 is a self-propelled punching machine capable of traveling in the traveling area by the traveling mechanism 8, from the viewpoint of reducing the weight of the punching machine main body 4, similarly to the main body 7A of the control device 7. The signal processing system 14 can be installed outside the traveling area. Therefore, a part of the signal processing system 14 may be integrated with the main body 7A of the control device 7.

The signal processing system 14 has a function of monitoring an abnormality in drilling using a drill based on the detection results of at least one of the vibration sensor 12 and the rotation speed sensor 13. When monitoring an abnormality based on the detection result of the vibration sensor 12, it corresponds to the waveform of the detection signal indicating the vibration of the drill detected by the vibration sensor 12 and the case where there is no abnormality in the drilling using the drill. By comparing with the reference waveform, it is possible to monitor the abnormality of drilling using a drill. On the other hand, when monitoring an abnormality based on the detection result of the rotation speed sensor 13, the rotation speed of the drill detected by the rotation speed sensor 13 and the rotation corresponding to the case where there is no abnormality in the drilling using the drill. Abnormality of drilling with a drill can be monitored by further comparison with the number.

The number of rotations of the drill can also be obtained by obtaining the period or frequency of the vibration of the drill detected by the vibration sensor 12. Therefore, the rotation speed sensor 13 may be omitted. In other words, the vibration sensor 12 may be used as the rotation speed sensor 13. In this case, both the vibration and the rotation speed of the drill can be detected by the common vibration sensor 12.

Specific examples of abnormalities in drilling using a drill include abnormalities in the drill itself such as missing drills and wear of the drills, as well as deviation of the tool axis of the drill from the central axis of the prepared hole provided in the work W in advance. An abnormality caused by a mispositioning of the drill, such as a deviation of the tool axis of the drill from the central axis of the guide hole provided in the drill plate 9, can be mentioned.

Abnormalities of the drill itself, such as drill defects and drill wear, can be detected mainly by measuring the amount of fluctuation in the number of revolutions of the drill.

FIG. 7 is a graph showing an example in which the rotation speed is reduced due to a missing drill.

In FIG. 7, the horizontal axis represents time, and the vertical axis represents the amount of fluctuation in the number of rotations of the drill. The amount of fluctuation in the rotation speed is shown as a ratio (%) with respect to the rotation speed of the spindle in a state where no load is applied.

In FIG. 7, the solid line shows the change in the number of rotations of the drill when drilling titanium and aluminum using a drill without defects as a ratio to the number of rotations of the spindle in a state where no load is applied. On the other hand, the alternate long and short dash line shows the change in the number of revolutions of the drill when drilling titanium and aluminum using a drill with a defect as a ratio to the number of revolutions of the spindle when no load is applied.

As shown by the solid line in FIG. 7, when titanium is drilled using a drill without a defect, the rotation speed is reduced by about 4% with respect to the rotation speed of the spindle when no load is applied. Further, when aluminum is drilled using a drill without a defect, the rotation speed is reduced in a range of approximately 3% to 4% with respect to the rotation speed of the spindle in a state where no load is applied.

On the other hand, as shown by the alternate long and short dash line in FIG. 7, when titanium and aluminum are drilled using a defective drill, the rotation speed is about 10% of the rotation speed of the spindle when no load is applied. The number of revolutions is decreasing. Therefore, if the drilling test result shown in FIG. 7 is obtained, the actual rotation speed of the spindle holding the drill is 10% or more or more than the control value of the rotation speed of the spindle during drilling of titanium or aluminum. If it decreases at a rate of more than 10%, it can be determined that the drill has a defect.

In the drilling test shown in FIG. 7, the control value of the rotation speed per minute of the spindle was set to 1000 (rpm), but if the rotation speed dependence of the decrease rate of the rotation speed cannot be ignored, it is set to various rotation speeds. Can perform a drilling test. Except for high-speed machining in a machining center or the like, the control value of the rotation speed per minute is about 200 (rpm) to 3000 (rpm). Therefore, the drilling test may be performed intermittently in the range of 200 (rpm) to 3000 (rpm), and the threshold value for determining that the drill is defective may be determined for each control value of the rotation speed by interpolation. ..

In addition to titanium and aluminum, other metals such as iron, as well as composite materials such as glass fiber reinforced plastics (GFRP: Glass fiber reinforced plastics) and carbon fiber reinforced plastics (CFRP: Carbon Fiber Reinforced Plastics) are targeted. A similar drilling test can be performed.

Then, a threshold value is set for the rate of decrease with respect to the rotation speed of the spindle in a state where no load is applied, and when the rate of decrease is equal to or greater than the threshold value or exceeds the threshold value, it can be determined that the drill has a defect. Similarly, a perforation test can determine a threshold for determining that the drill has experienced non-negligible wear. In addition, the threshold for detecting an abnormality in the drill is not limited to the rate of decrease with respect to the rotation speed of the spindle when no load is applied, but is set to the drill rotation speed itself or other desired index values indicating the amount of decrease in the drill rotation speed. May be set.

The threshold value for the index value representing the amount of decrease in the rotation speed of the drill can be stored in the storage device 14A of the signal processing system 14 as a table or a function in association with the drilling conditions such as the material of the work W and the rotation speed. This makes it possible to monitor an abnormality based on the rotation speed of the drill in the signal processing system 14.

On the other hand, abnormalities such as drill loss, drill wear, pilot hole displacement, and guide hole displacement provided in the drill plate 9 are detected by detecting abnormal drill vibration using the vibration sensor 12. can do.

The detection of the vibration waveform of an abnormal drill is a desired signal based on the waveform of the detection signal representing the vibration of the drill detected by the vibration sensor 12 and the reference waveform corresponding to the case where there is no abnormality in the drilling using the drill. It can be done by processing.

As a specific example, signal processing such as envelope detection processing can be performed on the detection signal representing the vibration of the drill detected by the vibration sensor 12. Then, the amplitude waveform of the detection signal detected by the vibration sensor 12 after the envelope detection is compared with the reference waveform corresponding to the case where there is no abnormality in the drilling using the drill, and the deviation from the reference waveform is shown. It can be determined that an abnormality has occurred when the index values such as the square error, the mutual correlation coefficient, the difference in the integrated value of the waveform, and the difference in the peak value exceed or exceed the threshold value.

Alternatively, the detection signal and the reference signal can be compared with frequency analysis such as Fourier transform (FT) or wavelet transform. Further, the MT method may be used in combination in order to obtain the amount of deviation of the vibration detection signal from the reference signal. The MT method is a method of obtaining the distribution of distances by determining the coordinates of a reference point in a multidimensional space and calculating the distance between the reference coordinates and the coordinates of each data.

FIG. 8 is a graph showing an example of comparing the frequency spectra obtained by applying FFT to the acceleration signal representing the vibration level of the drill.

In FIGS. 8 (A) and 8 (B), each horizontal axis represents frequency (Hz), and each vertical axis represents acceleration (m / s ² ) representing the vibration level of the drill on which vibrations of other mechanical elements are superimposed. Is shown. Further, FIG. 8A shows a frequency spectrum obtained by detecting the level of vibration during drilling of a drill without defects as acceleration by an acceleration sensor and by FFT of the acceleration detection signal. On the other hand, FIG. 8B shows a frequency spectrum obtained by detecting the level of vibration during drilling of a drill with a defect as acceleration by an acceleration sensor and by FFT of the acceleration detection signal. The drilling conditions using a drill without defects and the drilling conditions using a drill with defects are the same.

As shown in FIGS. 8A and 8B, the waveform of the frequency spectrum representing the vibration level of the drill changes depending on the presence or absence of defects. Specifically, two peaks are generated in each of the two frequency spectra shown in FIGS. 8 (A) and 8 (B). Then, as shown by the broken line frame in FIG. 8 (B), the peak value on the lower frequency side in the frequency spectrum corresponding to the drill having a defect is the frequency shown in FIG. 8 (A) corresponding to the drill without a defect. It is significantly larger than the peak value on the lower frequency side of the spectrum.

Therefore, the abnormality of the drill can be detected by comparing the waveform between the reference frequency spectrum acquired in advance under the drilling condition without abnormality and the frequency spectrum acquired as the abnormality detection target. That is, by performing signal processing including FT of the detection signal representing the vibration of the drill detected by the vibration sensor 12, a frequency spectrum regarding the amplitude of the detection signal is acquired, and the waveform of the acquired frequency spectrum and the reference waveform are used. By comparing with the reference waveform of the frequency spectrum prepared in advance, it is possible to monitor the abnormality of drilling using a drill.

As for the comparison of waveforms between frequency spectra, it is possible to compare desired representative values of frequency spectra such as an integral value, a peak value, and a frequency with respect to a peak value. That is, the threshold value for the index indicating the deviation between the frequency spectra can be performed by using the threshold value empirically determined by the perforation test or the like. Then, when it is determined that the index indicating the deviation between the frequency spectra is equal to or greater than the threshold value or exceeds the threshold value, it can be determined that an abnormality has occurred in the drill itself or the drilling.

As a more specific example, a threshold value can be set for the peak value itself of the frequency spectrum representing the vibration of the drill acquired by using the vibration sensor 12, or a threshold value can be set for the frequency band in which the peak value occurs. As a result, it is possible to automatically detect an abnormal peak that appears at a frequency that does not originally appear if there is no abnormality, or an abnormal increase in the peak value.

If an abnormality occurs in drilling with a drill, the rotation speed usually decreases. Therefore, the frequency at which the peak occurs in the frequency spectrum is often shifted to the lower side. In addition, when an abnormality occurs in drilling with a drill, the vibration level of the drill usually increases. Therefore, the peak value appearing in the frequency spectrum often increases. Therefore, threshold processing may be performed by setting threshold values for both the frequency band in which the peak occurs in the frequency spectrum and the peak value appearing in the frequency spectrum.

In addition, the vibration sensor 12 can detect vibrations in a plurality of spatially different axial directions. That is, the vibration of the drill can be detected as a vector. In that case, the frequency spectrum can be acquired and compared for each component of the vector, that is, for each spatial axis direction. This is also the case when the vibration detection signals are compared without generating the frequency spectrum.

Similar to the threshold value for the index value indicating the amount of decrease in the rotation speed of the drill, the threshold value for the index value indicating the fluctuation amount of the vibration of the drill can be used as a table or a function in association with the drilling conditions such as the material of the work W and the rotation speed. It can be stored in the storage device 14A of the signal processing system 14. This makes it possible to monitor an abnormality based on the vibration of the drill in the signal processing system 14.

Further, it is possible to specify a condition for determining the presence or absence of an abnormality by operating the input device 16. As a specific example, it is possible to set the target of the threshold value processing for determining the presence or absence of an abnormality and the threshold value used for the threshold value processing by operating the input device 16.

The threshold value for the index value indicating the fluctuation amount of the vibration of the drill and the threshold value for the index value indicating the decrease amount of the rotation speed of the drill both change depending on the material and the drilling condition. Therefore, information for specifying each threshold value can be recorded in the IC tag 10. That is, information for specifying a threshold value for an index representing the amount of deviation from the reference waveform of the waveform of the detection signal representing the vibration of the drill detected by the vibration sensor 12 can be recorded in the IC tag 10. Similarly, information for specifying a threshold value for an index value indicating the amount of decrease in the number of rotations of the drill can also be recorded in the IC tag 10.

As a practical example, when the IC tag 10 is attached to the drilling plate 9, the ID information of the drilling plate 9 is used as information for specifying a threshold value for detecting an abnormality in drilling using a drill. be able to. That is, the threshold value for detecting an abnormality can be associated with the ID information of the perforation plate 9 and stored as a table in the storage device 14A of the signal processing system 14.

Alternatively, when the IC tag 10 is directly attached to the work W, the ID information of the work W can be used as information for specifying a threshold value for detecting an abnormality in drilling using a drill. That is, the threshold value for detecting an abnormality can be associated with the ID information of the work W and stored as a table in the storage device 14A of the signal processing system 14.

Of course, regardless of whether the IC tag 10 is attached to the drilling plate 9 or the work W, the information for specifying the threshold value for the index value representing the fluctuation amount of the vibration of the drill and the drill As information for specifying the threshold value with respect to the index value representing the amount of decrease in the rotation speed, the value itself of each threshold value may be recorded in the IC tag 10.

Then, the information for specifying the threshold value recorded in the IC tag 10 can be read by the IC tag reader 11 and transferred to the signal processing system 14 wirelessly or the like. When the information read by the IC tag reader 11 is wirelessly transferred to the signal processing system 14, a dedicated radio may be provided in the signal processing system 14, but as illustrated in FIG. 1, the control device 7 The signal may be transferred to the signal processing system 14 by using the radio 7E provided in the main body 7A of the above.

Then, based on the information recorded on the IC tag 10 transferred wirelessly or the like, the signal processing system 14 can automatically specify each threshold value for threshold processing for abnormality determination.

That is, if the information transferred from the IC tag reader 11 is the ID information of the perforated plate 9 or the work W, the ID information of the plurality of perforated plates 9 or the plurality of work W stored in the storage device 14A and the ID information of the plurality of thresholds are set. By referring to the table associated with the combination, the threshold value for abnormality determination corresponding to the ID information can be specified. Alternatively, if the information transferred from the IC tag reader 11 is the threshold value for abnormality determination itself, the threshold value for abnormality determination corresponding to the perforated plate 9 or the work W is specified by acquiring the information transferred from the IC tag reader 11. be able to.

As a result, even if the material of the work W, the diameter and depth of the hole to be drilled, and the drilling conditions such as the diameter, material, structure, rotation speed, and feed rate of the drill are different, it is appropriate for each drilling condition. The threshold value can be automatically determined in the signal processing system 14. That is, it is possible to detect an abnormality regardless of the drilling conditions.

Then, in the signal processing system 14, when the index value to be subjected to the threshold value processing is equal to or higher than the specified threshold value or exceeds the threshold value, it can be automatically determined that an abnormality has occurred in the drilling using the drill. For example, if the threshold value is set according to the content of an abnormality such as a missing drill, wear of the drill, displacement of the prepared hole, and displacement of the guide hole provided in the drill plate 9, the drill is subjected to the threshold processing. It is possible to determine which of the defects, the wear of the drill, the displacement of the prepared hole, and the displacement of the guide hole provided in the perforated plate 9 has occurred.

When it is determined that an abnormality has occurred in the drilling using the drill, the display device 17 can display the abnormality as a monitoring result. Of course, the abnormality monitoring result may be output as light or sound to an output device such as an alarm lamp or a speaker. That is, the signal processing system 14 can be provided with a function of notifying the operator of the abnormality monitoring result by outputting the abnormality monitoring result to an output device such as the display device 17.

Further, when it is determined that an abnormality has occurred in the drilling using the drill, the drilling machine main body 4 can be controlled according to the content of the abnormality. For example, at least one of reduction of the control value of the rotation speed of the drilling machine main body 4, reduction of the control value of the feed rate in the tool axis direction of the drill, and interruption of drilling can be performed. In that case, the signal processing system 14 is provided with a function of giving necessary control information to the control device 7 of the drilling machine main body 4.

As a more specific example, if the content of the abnormality is an abnormality that can be tolerated in drilling, such as drill wear, an acceptable drill defect, or an acceptable drill misalignment, the rotation of the drilling machine main body 4 It is possible to reduce the control value of the number and the control value of the feed rate in the tool axis direction of the drill. On the contrary, if the content of the abnormality is a defect of the drill or a misalignment of the drill that leads to the occurrence of a defect, the drilling machine main body 4 for interrupting the drilling can be controlled. Specifically, it is possible to control the drill to be separated from the work W to stop the rotation of the drill and the control to move the drilling machine main body 4 to the retracted position.

On the other hand, the radio 15 of the drill abnormality detection system 3 has a function of wirelessly transmitting the detection signals output from the vibration sensor 12 and the rotation speed sensor 13 to the signal processing system 14. By wirelessly transferring the detection signals output from the vibration sensor 12 and the rotation speed sensor 13, the drilling machine 2 is a self-propelled device capable of traveling by the traveling mechanism 8. The vibration sensor 12 and the rotation speed sensor 13 can be easily attached to the drilling machine 2 regardless of the type of the above. In addition, the drill abnormality detection system 3 can be made small.

Therefore, the drill abnormality detection system 3 can be retrofitted to the existing drilling machine 2 as an attachment. Further, not only the drilling machine 2 provided with the self-propelled drilling machine main body 4 as shown in the drawing, but also the drilling machine such as a machining center and the drilling machine such as a hand-held drill drive device are provided with the drill abnormality detection system 3. Can be done. Even in that case, the IC tag 10 and the IC tag reader 11 can be provided as components of the drill abnormality detection system 3 as needed.

In the illustrated example, the vibration sensor 12 and the rotation speed sensor 13 are each provided with a radio device 15. Therefore, a troublesome signal cable can be eliminated. In particular, a battery-powered WiFi vibrator that detects the vibration of a vibrating body and transmits vibration detection data by WiFi communication, or a battery that detects the rotation speed of a rotating body and transmits the rotation speed detection data by WiFi communication. Driven WiFi tachometers are commercially available. Therefore, a battery-powered vibration sensor 12 and a rotation speed sensor 13 having a built-in radio 15 can be easily obtained so that a wired connection is not required.

Of course, similarly to the IC tag reader 11, the vibration sensor 12 and the rotation speed sensor 13 may be connected to the radio 7E for communication of control signals with a signal cable to make the radio common. That is, the IC tag reader 11, the vibration sensor 12, and the rotation speed sensor 13 may be provided with dedicated radios 11A and 15, respectively, or the radio 7E for communication of control signals may be used.

Alternatively, as described above, when the main body 7A and the control signal receiving device 7B are connected by a signal cable, or when the entire control device is mounted on the drilling machine, the vibration sensor 12 and the rotation speed sensor 13 are used. Also, the signal processing system 14 may be connected by wire. That is, at least one of the vibration sensor 12 and the rotation speed sensor 13 may be connected to the signal processing system 14 with a signal cable for transmitting the detection signal.

(Drill abnormality detection method and manufacturing method of the product to be drilled)
Next, a method for detecting a drill abnormality by the drill abnormality detection system 3 and a method for manufacturing a product to be drilled using the drilling system 1 will be described. Here, a case where the vibration sensor 12 and the rotation speed sensor 13 are attached to the punching machine main body 4 and the drilling plate 9 to which the IC tag 10 is attached is attached to the work W will be described as an example.

FIG. 9 is a flowchart showing an example of a flow in the case where the work W is drilled with the drilling abnormality monitoring using a drill by the drilling system 1 provided with the drill abnormality detection system 3 shown in FIG.

First, in step S1, the perforated plate 9 to which the IC tag 10 is attached is attached to the work W. The IC tag 10 is used for threshold processing for monitoring abnormalities in drilling, in addition to information referred to for controlling the drilling machine main body 4 such as information for specifying a drilling position and a hole diameter. Information for identifying the threshold is recorded. Alternatively, common information for specifying the threshold value referred to in the control of the punching machine main body 4 and used for the threshold value processing for monitoring the abnormality of the drilling, for example, the ID information of the drilling plate 9 is recorded.

More specifically, the information for specifying the threshold value for the index representing the amount of deviation from the reference waveform of the waveform of the detection signal representing the vibration of the drill detected by the vibration sensor 12 and the rotation speed sensor 13 are detected. Information for specifying a threshold value for an index value representing the amount of decrease in the rotation speed of the drill from the reference rotation speed is recorded in the IC tag 10.

Next, in step S2, the driving of the drilling machine main body 4 is started. That is, the traveling mechanism 8 travels on the upper surface of the long structure W2 constituting the work W by remote control by the control device 7, and the drilling machine main body 4 moves to the initial position for starting drilling.

Next, in step S3, the information recorded on the IC tag 10 is read by the IC tag reader 11 attached to the punching machine main body 4. The read information is wirelessly transferred from the radio 11A of the IC tag reader 11 to the radio 7E provided in the main body 7A of the control device 7.

Then, the information referred to for controlling the punching machine main body 4 is given to the control signal generation unit 7D. On the other hand, the information for monitoring the abnormality of the drilling is given to the signal processing system 14 of the drill abnormality detection system 3.

Next, in step S4, the threshold value used for the threshold value processing for performing abnormality monitoring in the signal processing system 14 is specified based on the information wirelessly transferred from the IC tag reader 11. For example, when the ID information of the perforated plate 9 recorded on the IC tag 10 is transferred from the IC tag reader 11 to the signal processing system 14, the perforated plate 9 can be referred to by referring to the table stored in the storage device 14A. The threshold value corresponding to the ID information of is specified in the signal processing system 14.

As a result, while the drill is rotationally driven, the drilling machine main body 4 is moved to sequentially perform drilling at different positions of the work W, and it is possible to monitor an abnormality in drilling using the drill during rotation.

Next, in step S5, the work W is drilled by remotely controlling the drilling machine main body 4 by the control device 7. Specifically, the control signal of the punching machine main body 4 generated by the control signal generation unit 7D of the control device 7 is wirelessly transmitted from the radio 7E. The transmitted control signal is received by the control signal receiving device 7B. Then, the punching machine main body 4 is driven according to the control signal received by the control signal receiving device 7B. That is, in addition to the rotation and feeding of the drill, the feeding operation of the drill head 5 by the feeding mechanism 6 and the traveling of the traveling mechanism 8 are performed so that the drilling is performed at the drilling position specified based on the ID information of the drilling plate 9. The drilling machine main body 4 is run.

On the other hand, during the drilling of the work W, the vibration sensor 12 is used to detect the vibration of the drill during rotation. Further, the rotation speed sensor 13 detects the rotation speed of the drill during rotation.

Next, in step S6, the detection signal representing the vibration of the drill detected by the vibration sensor 12 and the detection signal representing the rotation speed of the drill detected by the rotation speed sensor 13 are wirelessly transmitted from the radio device 15, respectively. ..

Next, in step S7, each detection signal representing the vibration and the rotation speed of the drill transmitted wirelessly is received by the wireless device 7E provided in the main body 7A of the control device 7. Each received detection signal is given to the signal processing system 14 of the drill abnormality detection system 3.

Next, in step S8, the signal processing system 14 detects an abnormality in drilling using a drill based on each detection signal representing the vibration and rotation speed of the drill and a threshold value used for threshold processing for performing abnormality monitoring. Monitor.

That is, the signal processing system 14 monitors the abnormality of the drill using the drill by comparing the waveform of the detection signal representing the vibration of the drill with the reference waveform corresponding to the case where there is no abnormality in the drill using the drill. do. Further, the signal processing system 14 determines the actual rotation speed of the drill specified based on the detection signal detected by the rotation speed sensor 13 and the rotation speed corresponding to the case where there is no abnormality in the drilling using the drill. Monitor abnormalities in drilling drills by comparison.

Then, when the index value indicating the amount of deviation between parameters such as acceleration and rotation speed to be compared exceeds the permissible value corresponding to the index value, that is, when it exceeds the threshold value or exceeds the threshold value, drilling using a drill is performed. It can be determined in the signal processing system 14 that an abnormality has occurred in the signal processing system 14. Further, if the threshold value is set according to the content of the abnormality such as the defect of the drill, the wear of the drill, the displacement of the prepared hole, and the displacement of the guide hole provided in the drilling plate 9, the drill is performed by the threshold processing. It is possible to determine which of the defects, the wear of the drill, the displacement of the prepared hole, and the displacement of the guide hole provided in the perforated plate 9 has occurred.

When comparing the detection signals representing the vibration of the drill, frequency analysis processing such as FT can be executed on the detection signal as a preprocessing of the comparison processing. In that case, by performing signal processing including FT of the detection signal representing the vibration of the drill, a frequency spectrum regarding the amplitude of the detection signal detected as acceleration or the like is acquired. Then, the abnormality of the perforation using the drill is monitored by comparing the acquired frequency spectrum waveform with the reference waveform of the frequency spectrum prepared in advance as the reference waveform.

Next, in step S9, the abnormality monitoring result in the signal processing system 14 is notified to the operator via an output device such as a display device 17. For example, when an abnormality is detected, the operator can be notified of the details of the abnormality such as a missing drill, wear of the drill, displacement of the prepared hole, and displacement of the guide hole provided in the drilling plate 9.

Next, in step S10, the necessary drilling machine 2 is controlled according to the abnormality monitoring result. For example, if an acceptable abnormality such as expected drill wear is detected, the control value of the rotation speed of the drill built in the drill head 5 is reduced or the drill head 5 is built in. It is possible to reduce the control value of the feed rate with respect to the feed mechanism of the drill. On the contrary, even if the drill is worn, the work W is worn to a degree that cannot be ignored, or the drill is chipped or misaligned to the extent that the work W is not to be ignored. If so, the perforation can be interrupted.

When controlling the drilling machine 2 according to the abnormality monitoring result, control information is given from the signal processing system 14 to the control signal generation unit 7D of the control device 7. Then, the control signal generation unit 7D generates a control signal of the drilling machine main body 4 according to the control information given from the signal processing system 14. The generated control signal is wirelessly transmitted to the control signal receiving device 7B on the punching machine main body 4 side via the radio 7E. As a result, the drilling machine main body 4 operates according to the abnormality monitoring result.

On the other hand, when no abnormality is detected and the drilling at all the drilling positions of the work W is completed by the driving of the drilling machine main body 4 including the rotation drive and movement of the drill, the drilling machine main body 4 is retracted under the control of the control device 7. Move to. Thereby, the product to be drilled can be manufactured as a product or a semi-finished product. Since the product to be drilled thus manufactured is manufactured by using a drill having a small amount of wear and maintaining the quality, the product to be drilled is of high quality.

(effect)
In the drill abnormality detection system 3, the drill abnormality detection method, the drilling system 1, and the manufacturing method of the product to be drilled as described above, at least one of the vibration and the rotation speed of the drill is detected by a sensor, and the vibration or the rotation speed of the drill fluctuates. It is possible to detect abnormalities during drilling using a drill, such as drill chipping, wear, and misalignment, based on the amount. In addition, the signal detected by the sensor is output wirelessly.

Therefore, according to the drill abnormality detection system 3, the drill abnormality detection method, the drilling system 1, and the manufacturing method of the product to be drilled, it is possible to detect abnormalities such as chipping, wear, and misalignment of the drill during drilling. As a result, the accuracy of drilling can be improved. That is, the quality of the product to be drilled can be improved. As a result of an actual drilling test, it was confirmed that drilling can be performed with an error of 0 mm to +0.0762 mm with respect to the designed hole diameter, that is, the reference diameter of the drill.

Further, when an abnormality is detected, the content of the abnormality can be confirmed, and when an unacceptable abnormality is detected, the perforation can be interrupted to prevent continuous defects from occurring. .. Further, when a new type of abnormality is found by a drilling test or the like, the criteria for determining the abnormality can be easily changed. It is also possible to adjust the abnormality detection sensitivity.

Moreover, the parts such as the vibration sensor 12 and the rotation speed sensor 13 constituting the drill abnormality detection system 3 can all be miniaturized, and a wired connection can be eliminated for power supply and data communication. Therefore, the drill abnormality detection system 3 can be mounted on various types of drilling machines.

For example, by adding the drill abnormality detection system 3 to a drilling machine that is already in operation, it is possible to provide an abnormality detection function during drilling. In particular, in order to monitor vibration and rotation speed for abnormality detection, which is easy to monitor regardless of the type of drilling machine, the drill abnormality detection system 3 is used not only for electric punching machines but also for air-driven drilling machines. Can be provided. Further, since a wired connection can be eliminated, even a drilling machine 2 equipped with a self-propelled punching machine main body 4 as shown in the figure or a punching machine used by bringing it to a place where there is no power supply facility can be drilled. By providing the abnormality detection system 3, abnormality monitoring can be performed.

(Other embodiments)
Although the specific embodiments have been described above, the described embodiments are merely examples and do not limit the scope of the invention. The novel methods and devices described herein can be embodied in a variety of other modes. In addition, various omissions, substitutions and changes can be made in the methods and devices described herein without departing from the gist of the invention. The appended claims and their equivalents include such various modalities and variations as incorporated in the scope and gist of the invention.

1 Drilling system 2 Drilling machine 3 Drill abnormality detection system 4 Drilling machine body 5 Drill head 5A Casing 5B Rotating shaft 6 Feeding mechanism 6A Rack and pinion 6B Motor 7 Control device 7A Main body 7B Control signal receiver 7C Storage device 7D Control Signal generator 7E Radio 8 Travel mechanism 8A First travel mechanism 8B Second travel mechanism 9 Perforated plate 10 IC tag 11 IC tag reader 11A Radio 12 Vibration sensor 13 Rotation speed sensor 14 Signal processing system 14A Storage device 15 Radio 16 Input device 17 Display device W Work W1 Plate-shaped part W2 Long structure

Claims (3)

A drilling machine that drives the drill to rotate, a vibration sensor that is attached to the drilling target by the drill or a drilling plate attached to the drilling target and directly or indirectly detects the vibration of the drill during rotation.
By comparing the waveform of the detection signal indicating the vibration of the drill detected by the vibration sensor with the reference waveform corresponding to the case where there is no abnormality in the drill using the drill, the abnormality in the drill using the drill is compared. Signal processing system to monitor and
With a drill abnormality detection system,
With the drilling machine
An integrated circuit tag attached to at least one of the perforation target and the perforation plate and recording information for specifying a threshold value for an index value representing the amount of deviation of the detection signal waveform from the reference waveform.
A reader attached to the drilling machine side, reading the information recorded in the integrated circuit tag, and transferring the information to the signal processing system.
With
The signal processing system identifies the threshold value based on the transferred information, and determines that an abnormality has occurred in the drilling using the drill when the index value is equal to or higher than the threshold value or exceeds the threshold value. Consists of a perforation system. A step of directly or indirectly detecting the vibration of the drill during rotation by using a drilling machine for rotating the drill, a drilling target by the drill or a vibration sensor attached to a drilling plate attached to the drilling target, and a step of directly or indirectly detecting the vibration of the drill during rotation.
A step of monitoring an abnormality in drilling using the drill by comparing a waveform of a detection signal indicating the vibration of the drill detected by the vibration sensor with a reference waveform corresponding to the case where there is no abnormality in the drill. When,
Have a,
An integrated circuit tag recording information for specifying a threshold value for an index value representing the amount of deviation of the detection signal waveform from the reference waveform is attached to at least one of the perforation target and the perforation plate.
The information recorded on the integrated circuit tag is read by a reader attached to the drilling machine side and transferred.
Identify the threshold value based on the transferred the information, drill abnormality detection method for determining said index value abnormality occurs in drilling with the drill when it exceeds the threshold value or more or the threshold. A step of monitoring an abnormality in drilling using a drill during rotation by the drill abnormality detection method according to claim 2, and a step of monitoring the abnormality.
A step of manufacturing a product to be drilled by rotationally driving the drill with the drilling machine to perform drilling of the drilling target.
A method for manufacturing a product to be perforated.

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