JP4112774B2 - Apparatus and method for monitoring rotation failure of rotating body in processing equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a rotation failure monitoring apparatus and method for a rotating body such as a roller guide in a rolling facility.
[0002]
[Prior art]
Known rotation detection of the roller guide is disclosed in Japanese Utility Model Laid-Open No. 4-108907.
In this conventional apparatus, a detection piece provided on a roller is detected by a rotation detection sensor, and an electric signal corresponding to the number of rotations is extracted to determine whether rotation is defective.
The rotation failure is determined to be defective when the number of rotations of the roller detected by the rotation detection sensor falls below a predetermined value.
[0003]
[Problems to be solved by the invention]
Conventionally, it is not possible to determine whether or not there is a rotation failure only by the detected number of rotations of the roller. That is, it can be determined only by comparing the rotation speed with a predetermined value (reference rotation speed).
However, the passing speed of the material passing through the roller may be changed. In this case, the reference rotational speed must also be changed, which is complicated.
[0004]
[Means for Solving the Problems]
The present inventor observed that a signal that changes with time depending on the rotation angle of the roller was analyzed by frequency analysis, and when the roller stopped or decreased, the main component frequency decreased and noise was reduced. It has been found that the component increases and the level difference between the main component and the noise component decreases. The inventor of the present invention has invented an unprecedented defective rotation device and method using this.
That is, the feature of the present invention is the rotation failure monitoring device for a rotating body in a processing facility provided with a pair of upper and lower rotating bodies that are rotated in contact with the workpiece or rotated to send the workpiece. upper and lower time-varying signal depending on the rotation angle of the rotating body respectively detected, and the frequency detector for determining the frequency components of the signal the signal of the upper and lower rotary bodies each by frequency analysis, frequency analysis The difference between the principal component frequencies of the upper and lower rotating bodies among the frequency components obtained in the above is compared, and the rotation failure of the upper and lower rotating bodies is determined based on the level of at least one main component frequency of the upper and lower rotating bodies. And a rotation failure determination unit for determining.
[0005]
In the present invention, the rotating body includes both a rotating body that is rotated by moving the workpiece, such as a roller guide, and a rotating body that is rotationally driven to feed the workpiece.
In addition, the rotation failure determination unit is configured such that the difference between the principal component frequencies of the upper and lower rotating bodies is out of a predetermined range, and the level ratio of the low frequency component level to the principal component frequency level exceeds a predetermined ratio. If the, it is preferable to determine the rotation failure.
In addition, the rotating body is configured such that a roller is rotatably provided on a roller shaft, a passage is provided in an axial direction from one end of the roller shaft, and a passage is provided in a radial direction in communication with the passage. A pipe for applying a gas pressure to the opening at the axial end of the passage provided in the axial direction on the inner peripheral surface of the roller facing the opening of the passage provided in the direction. And a pressure detection device is connected to the pipe line, and the frequency detection unit preferably performs frequency analysis on a pressure change signal detected by the pressure detection device.
[0006]
Further, it is preferable that the workpiece is a steel bar and the processing equipment is a finishing block mill or a sizing mill subsequent thereto.
Further, the method according to the present invention is the rotation failure monitoring method for a rotating body in a processing facility provided with a pair of upper and lower rotating bodies that are rotated in contact with the workpiece or rotated to send the workpiece. upper and lower time-varying signal depending on the rotation angle of the rotating body to detect respectively, the signal of the upper and lower rotary bodies each with frequency analysis determined the frequency components of the signal, the upper and lower rotary bodies, respectively The difference between the principal component frequencies is compared, and the rotation failure of the upper and lower rotating bodies is determined based on at least the level of one principal component frequency of the upper and lower rotating bodies .
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a rolling equipment 1 for steel bars (wires, bars, etc.) to which the present invention is applied. This rolling equipment 1 has a heating furnace 2, and in order to roll a material to be rolled (workpiece) fed from the heating furnace 2, a coarse rolling mill 3, one intermediate row from the heating furnace 2 side. A rolling mill 4 and a two-middle row rolling mill 5 are arranged. The downstream side of the two-intermediate rolling mill is branched, one is provided with a winding machine 6, the other is provided with a finishing block mill 7, and the finishing block mill 7 is followed by a sizing mill 8. ing. A roller conveyor 9 is connected to the downstream side of the sizing mill 8. The rolling facility 1 includes a rolling operation room 10 for an operator to monitor and operate the rolling operation. The rolling operation room 10 is installed at a location away from other equipment of the rolling equipment 1.
[0008]
FIG. 2 shows an example in which the rotating body defect monitoring device 11 according to the present invention is applied to the finishing block mill 7 and the sizing mill 8.
The finishing block mill 7 is mainly configured by arranging a plurality of stands in the flow direction of the material to be rolled in the housing 13. Although not shown, the finishing block mill 7 is provided with eight stands, and vertical (elliptical caliber) rolling rolls and horizontal (circular caliber) rolling rolls are alternately arranged in the material flow direction. Has been.
A vertical stand and a horizontal stand on the downstream side form a set, and roller guides 14 are provided between the stands forming the set. That is, the roller guides 14 are respectively provided on the upstream side of the horizontal stand (a total of four). These roller guides 14 are for stably supplying hot steel to a horizontal stand. The roller guide 14 is provided with an upper roller guide 14a and a lower roller guide 14b at each position, and the upper and lower roller guides 14a and 14b are provided in pairs so as to face each other vertically with the material to be rolled interposed therebetween. Yes. Although this roller guide 14 is not driven, while repeated high-speed rotation with hot steel, rotation failure such as bearing seizure sometimes occurs and induces quality defects and misrolls.
[0009]
The sizing mill 8 is also provided with a single stand on the housing 16, and this stand is also provided with a roller guide 14 for stably supplying the material to be rolled. In the following, among the stands provided in the finishing block mill 7, the stands provided with the roller guide 14 for supplying the material are referred to as “stand 22 st” and “stand 24 st” from the upstream side in the material flow direction. "Stand 26st" and "Stand 28st". The stand of the sizing mill 8 is referred to as “stand 30st.” The position of the roller guide is not limited to the above.
[0010]
3 and 4 show the roller guide 14. This roller guide 14 includes a roller 101 having a caliber for guiding a material to be rolled formed on the outer peripheral surface, a collar 102 is formed at the center of the inner peripheral surface of the roller 101, and ball bearings 104 on both sides thereof. Can be accommodated.
The roller shaft 107 of the roller 101 has a bolt shape, a shoulder 112 for receiving the ball bearing 104 is formed on the head 110 side, and a screw for screwing the nut 108 is formed on the tip. Further, a supply hole 111 for lubricating oil (oil air) to the ball bearing 104 is drilled from the head 110 side to the center of the shaft at the center of the shaft and communicates with a supply hole 11a formed in the radial direction at the center of the shaft. ing.
[0011]
The roller 101 is supported by a roller support body 105, and the support body 105 has roller shaft support members 106, 106 formed at one end in a fork with a larger interval than the thickness of the roller 101, and this roller shaft support member 106. 106, a hole 109a for attaching the roller shaft 107 is formed, and one roller shaft support member 106 has a hole 109 for non-rotatingly accommodating the head 110 of the roller shaft 7 from the outer surface side. The other roller shaft 106 is formed with a hole 9b for rotatably accommodating the nut 108 from the outer surface side.
[0012]
A spacer ring 116 is provided between the roller 101 and the roller shaft 107. The spacer ring 116 is slightly thinner (about 0.5 mm) than the thickness of the collar 102 at the center of the inner peripheral surface of the roller 101. The donut plate-shaped small-diameter spacer ring 117 having an inner diameter slightly larger (about several mm) than the outer diameter of the roller shaft 107, and an inner diameter slightly larger (about 0.5 mm) than the outer diameter of the small-diameter spacer ring 117 and A large-diameter spacer ring 118 having a thickness substantially the same as the thickness of the collar 102 at the center of the inner peripheral surface of the roller 101 is formed, and a through-hole 119 is formed in the center of the small-diameter spacer ring 117 in the radial direction. On the other hand, a groove 120 is formed in the inner periphery of the large-diameter spacer ring 118.
[0013]
The guide roller having the above structure is assembled by the following procedure.
(1): The large-diameter spacer ring 118 is non-rotatably fitted to the inner periphery of the collar 102 of the roller 101, and the ball shaft 104 is mounted from both sides of the roller 101 so that the small-diameter spacer ring 117 is sandwiched between the inner rings of the ball bearings 104. Enter.
(2): The assembly assembled as described in (1) above is inserted between the roller shaft support members 106, 106 of the roller support body 105, and the roller shaft 107 is inserted into the hole 109 side of the roller shaft support member 106. The bearing pressing ring 113 is inserted between the inner ring of the ball bearing 104 opposite to the insertion direction and the roller shaft support member 106 in the insertion process.
(3): After the roller shaft 107 is inserted, the roller shaft 107 is inserted into the hole 109b of the roller shaft support member 106, the spring washer 114 is inserted, and the nut 108 is tightened. As a result, the small-diameter spacer ring 117 is fastened between the inner rings of the two ball bearings 104 and is non-rotatably attached to the roller shaft 107, and the space 21 communicating with the supply shaft 111 a and the through-hole 119 between the roller shaft 107. Is formed.
(4): Next, a conduit 122 for supplying oil / air is connected to the supply hole 111 of the head 10 of the roller shaft 107, and a pressure detection device 123 is connected in the middle of the conduit 122. Oil-air pipes 122 are provided in the respective roller guides 14, and pressure detectors 123 are provided in the respective pipes 122. The pressure detection device 123 is provided outside the housings 13 and 16 to avoid the influence of heat. Further, the pressure detection device 123 is provided in the vicinity of the housings 13 and 16 to prevent delay of pressure detection.
[0014]
In the roller guide 14 configured as described above, the oil air supplied through the conduit 122 is supplied to the ball bearing 104 through the supply holes 111 and 111a, the space 121, and the through hole 119. In this supply process, when the roller 101 rotates, the large-diameter spacer ring 118 rotates with the rotation, whereby the groove 120 formed in the large-diameter spacer ring 118 opens and closes the through hole 119 formed in the small-diameter spacer ring 117. To do. The pressure detection device 123 detects a change in pressure at the time of opening and closing. Further, since the pressure detection device 123 is provided corresponding to the plurality of roller guides 14, it is possible to detect pressure fluctuations caused by the rotation of the respective roller guides 14.
[0015]
Oil-air pressure fluctuations occur four times per rotation of the roller guide 14. FIG. 5 shows a signal waveform of the pressure fluctuation detected by the pressure detection device 123. When the groove 120 of the large diameter spacer ring 118 opens the through hole 119 formed in the small diameter spacer ring 117 as shown in FIG. 5A, the pressure in the pipe line 122 decreases. On the other hand, when the through hole 119 is closed as shown in FIG. 5B, the pressure in the pipe line 122 is increased. The pressure fluctuation signal changes depending on the rotation angle of the roller guide. That is, this signal has a frequency proportional to the number of rotations of the roller guide 14. In FIG. 5, two cycles of pressure fluctuation correspond to one rotation of the roller guide 14.
[0016]
The pressure fluctuation signal output from the pressure detection device 123 is amplified by the amplifier 35 and given to the control device 37. The amplifier 35 is provided in a local device storage board 36 installed in the vicinity of the finishing block mill 7 or the like. The control device 37 is installed in the rolling operation room 10.
As shown in FIG. 6, the pressure detection device 123, the amplifier 35, a high-pass filter 38 described later, and the like constitute an input unit of the monitoring device 11.
The control device 37 includes an A / D converter 39 for converting a pressure fluctuation signal, which is an analog signal, into a digital signal in addition to the high-pass filter 38, and a computer (general-purpose personal computer) connected to the A / D converter 39. 40. The computer 40 includes a display device as the display device 40a. Further, the computer 40 is communicably connected to a rolling line master control device 41 that is a rolling control device 41 that controls the rolling line, and can exchange information with the rolling control device 41.
[0017]
The computer 40 also has a program that functions as a low-pass filter unit 43 that filters A / D converted data, an FFT conversion unit 44 that performs FFT conversion on the filtered data, and a rotation failure determination unit 45 that determines rotation failure. keeping. The low-pass filter unit 43 and the FFT conversion unit 44 constitute a signal processing unit together with the A / D converter 39.
Note that the frequency of the pressure fluctuation signal, which is a signal that changes depending on the rotation angle of the roller guide, is detected by each function from the pressure detection device 123 to the FFT conversion unit. The detection unit 33 is configured.
[0018]
FIG. 7 shows the flow of monitoring processing by the monitoring apparatus 11. First, when the apparatus 11 is started up, the system is initialized. Then, the state of the rolling line is determined. This line state determination includes metal-in determination and use stand determination.
The metal-in determination is a determination as to whether or not the material to be rolled is on the line, and the determination result is used to display whether the material is being monitored or is on standby on a monitoring status display screen described later. If there is no material to be rolled, monitoring is unnecessary and it is only necessary to stand by.
[0019]
The use stand is determined for monitoring the use stand and displaying it on the screen. The stand used is changed by changing the rolling size or product quality. For example, all the stands 22st, 24st, 26st, 28st, 30st are used for a certain type of rolling, while only some of the stands 22st, 24st, 30st may be used for other types of rolling. . Further, for other types of rolling, some other stands 22st, 24st, 28st may be used. Since the stand that is not used does not have the rolling roller or the roller guide 14, it is not necessary to monitor the roller guide 14.
[0020]
The use stand information for each rolling method is held in the memory as a data table by the rolling control device 41, and the monitoring device 11 should take in the use stand information from the rolling control device 41 and monitor it. Recognize the stand.
Therefore, even if the stand configuration is changed by changing the rolling size, only the use stand is automatically diagnosed.
When the monitoring of the roller guide 14 is started, the pressure fluctuation analog signal output from the pressure detection device 123 is filtered by the high-pass filter 38, supplied to the A / D converter, and converted into digital data. This digital data is stored in the memory of the computer 40. This digital data is filtered by the low-pass filter 43 and subjected to FFT analysis by the FFT conversion unit. The change speed of the pressure fluctuation is very fast (rotational speed of the roller guide: 20,000 to 30,000 rpm), so that it is difficult to handle the raw data as it is, but the handling becomes easy by FFT analysis.
[0021]
A frequency component of pressure fluctuation is obtained by the FFT analysis, and roller rotation detection processing is performed based on the frequency component. By this processing, the main component (primary component) frequency of the pressure fluctuation is obtained. The principal component frequency is generally the highest level frequency, and can be obtained by creating a peak list and a harmonic list from the data after the FFT conversion. Further, when there is no main component, rotation is not monitored.
When this processing is performed, the frequency (main component frequency) of the oil-air pressure change caused by the rotation of the roller guide 14 as shown in FIG. 8B from the collected pressure fluctuation data as shown in FIG. Is required. This pressure change frequency indicates the rotation state of the roller guide 14, and if the rotation of the roller guide 14 decreases or stops, the frequency changes.
[0022]
The rotation failure determination unit 45 performs rotation failure diagnosis based on the frequency component of the pressure fluctuation. The determination for failure diagnosis is performed by using (1) determination based on the difference in rotation speed of each roller guide and (2) rotation stop determination based on the frequency distribution.
The rotational speed difference determination of (1) is performed by comparing the frequencies of the signals detected by the pressure detection devices 123 provided corresponding to the upper and lower roller guides 14a and 14b that are paired with the material to be rolled interposed therebetween. .
This comparison is performed by calculating the difference between the principal component frequency obtained for the upper roller guide 14a and the principal component frequency obtained for the lower roller guide 14b. The difference is calculated when the larger one of the two principal component frequencies to be compared is the principal component frequency A and the smaller one is the principal component frequency B. Difference = (principal component frequency A−principal component frequency B) / Main component frequency × 100 (%).
[0023]
For example, as shown in FIG. 9, when the main component frequency of the upper roller guide 14a is 300 Hz and the main frequency component of the lower roller guide 14b is 320 Hz, the difference is calculated as 6.25%.
According to this determination method, when any of the rotation speeds of the roller guides 14 to be compared decreases or stops, it can be immediately determined that the rotation is abnormal. Further, as in the prior art, a reference value corresponding to the passing speed of the material to be rolled becomes unnecessary.
When the calculated difference exceeds a predetermined range, it is determined that there is a rotation difference between the upper roller guide 14a and the lower roller guide 14b and that rotation is defective. The predetermined range reference value for determining whether or not the difference is within the allowable range is set in advance in the rotation failure determination unit 45, but it is preferable that the setting can be changed manually for accuracy change. It should be noted that the setting can be changed for each roller guide or each stand.
[0024]
The rotation stop determination of (2) is according to the present invention, and is performed based on the frequency component of the signal detected by the pressure detection device 123. Based on the frequency analysis results, the frequency components are arranged in order from the highest level, and the highest level (principal component) is compared with the Nth largest (low level component). When the ratio of the low-level component to exceeds a predetermined ratio set in advance, it is determined that the rotation of the roller guide 14 is stopped.
It has been empirically found that when the rotation of the roller guide 14 stops, the level of the main component decreases and the noise increases, and this is used to detect the rotation stop. . With this determination method, it is not necessary to compare the rotations of the plurality of roller guides 14, so that even when all the roller guides 14 are stopped, it is possible to reliably determine a rotation failure. In particular, by combining with the determination of (1), it is possible to determine rotation failure more reliably.
[0025]
FIG. 10 shows a case where the upper roller guide 14a rotates normally and the lower roller guide 14b stops. In FIG. 10, the frequency components obtained by FFT conversion are arranged in order from the highest frequency level to the lowest. That is, the component with the highest level located on the left side in FIG. 10 is the principal component frequency, and is arranged so that the level decreases as it goes to the right side.
As shown in FIG. 10A, since the upper roller guide 14a is normally rotated, the main component is large and the difference from the Nth (14th in the figure) component is sufficiently large. The level ratio of the Nth frequency component to the main component is 6%. Thus, if the ratio is small, it is determined that the motor is rotating normally.
[0026]
On the other hand, as shown in FIG. 10 (b), since the lower roller guide 14b is stopped or stopped, the level of the main component decreases, and conversely, the low level component increases due to noise, and the difference between the two is small. It has become. Here, the level ratio of the Nth frequency component to the main component is 25%. Since this level ratio is high, it is determined that the rotation is defective because the level of the main component has decreased. Note that the ratio (predetermined ratio) that serves as a reference for whether the rotation ratio is good or bad is set in advance in the rotation failure determination unit 45, but it is preferable that the setting can be changed manually for accuracy change. It should be noted that the setting can be changed for each roller guide or each stand. Further, it is preferable that the value of N can be manually changed.
[0027]
The rotation failure determination result as described above is always displayed on the monitor display screen 50 of the display device 40a. This screen 50 is a monitoring stand state display unit 51 that displays a stand to be monitored (used stand), and a current monitoring state display unit that displays what state (standby or monitoring) the current monitoring function is in. 52, a monitoring setting item display unit 53 for displaying the value of a setting item for monitoring, a stand state display unit 54 for displaying a graph of the status of each stand being monitored, and the latest abnormality for displaying the latest abnormality information when an abnormality occurs An information display unit 55 is included.
[0028]
The monitoring stand status display unit 51 displays the currently used stand 14 based on the use stand information. In FIG. 11, all the stands “22, 24, 26, 28, 30” are displayed, indicating that all the stands are used and are monitored. For example, if the use stand is changed to “22st, 24st, 30st”, “22, 24, 30” is displayed on the stand state display unit 51.
In the current monitoring state display section 52, the result of the metal-in determination is displayed. If there is no material to be rolled and monitoring is not necessary, “Standby” is displayed as shown in FIG. “Monitoring” is displayed.
[0029]
The stand status display unit 54 displays a graph of the status of each currently used stand based on the use stand information. In FIG. 11, since all the stands are used, the states of all the stands are displayed. The contents of the displayed graph are the main components of the upper roller guide 14a and the lower roller guide 14b.
If the rotation failure determination unit 45 determines that the rotation is defective, an abnormality process is performed. The abnormality processing includes abnormality alarm processing and abnormality data storage processing. In the abnormality alarm processing, the stand 14 in which an abnormality has occurred in the screen 50 is highlighted and a buzzer sounds to warn. Even after the abnormality occurs, the rotation failure determination process continues.
[0030]
In the abnormal data saving process, records such as the data after FFT conversion, the date and time of occurrence of the abnormality, and the stand number of the abnormality are stored in a storage unit such as a hard disk of the computer.
FIG. 12 specifically shows the state of data after FFT conversion when the upper and lower roller guides 14a and 14b rotate normally, and FIG. 13 shows when the lower roller guide 14b stops. In the case of FIG. 12, the main component frequency of the upper roller 14a is 180 Hz, and the main component frequency of the lower roller 14b is 183 Hz. The difference in frequency between the two is small, and the main component is sufficiently large with respect to the noise component, so that it is determined as normal.
[0031]
On the other hand, in the case of FIG. 13, the main component frequency of the upper roller 14a is 180 Hz, and the main component frequency of the lower roller 14b is 361 Hz. Further, it is also judged as defective because the level of the main component frequency is decreased and the level of the opposite noise is increased.
The present invention is not limited to the above embodiment. In particular, the application of the present invention is not limited to rolling equipment, but can also be applied to other equipment having a rotating body.
[0032]
【The invention's effect】
According to the present invention, it is possible to determine a rotation failure of a rotating body without using a reference rotation speed that varies depending on the speed of the workpiece.
[Brief description of the drawings]
FIG. 1 is a diagram showing an outline of rolling equipment to which the present invention is applied.
FIG. 2 is a schematic view of an apparatus when the present invention is applied to a finishing block mill and a sizing mill.
FIG. 3 is a cross-sectional explanatory view of a roller guide.
4 is a cross-sectional view taken along line XX in FIG.
FIG. 5 is an explanatory diagram showing a relationship between a rotation state of a guide roller and a pressure fluctuation signal.
FIG. 6 is a schematic diagram of a device including a detailed configuration of a control device.
FIG. 7 is a flowchart showing a process flow of the monitoring apparatus.
FIG. 8 is an explanatory diagram showing that a frequency of pressure change is obtained by FFT analysis from a signal detected by a pressure detection device.
FIG. 9 is an explanatory diagram of a rotation failure determination method based on a rotation difference.
FIG. 10 is an explanatory diagram of a rotation failure determination method based on a frequency distribution.
FIG. 11 is an explanatory diagram of a monitoring status display screen.
FIG. 12 shows data after normal FFT conversion.
FIG. 13 shows data after FFT conversion when the lower roller is stopped.
[Explanation of symbols]
1 Rolling Equipment 11 Rotation Failure Monitoring Device 14 Roller Guide 33 Frequency Detection Unit 45 Rotation Failure Determination Unit

Claims (6)

In a rotation failure monitoring device for a rotating body in a processing facility provided with a pair of upper and lower rotating bodies (14a, 14b) that are rotated in contact with the workpiece or rotated to send the workpiece,
Said upper and lower rotary bodies (14a, 14b) the time-varying signal depending on the rotation angle of the respectively detected, the frequency of the upper and lower rotary bodies (14a, 14b) the signal by frequency analyzing the signal for each A frequency detector (3) for obtaining a component;
Among the frequency components obtained by frequency analysis, the difference between the main component frequencies of the upper and lower rotating bodies (14a, 14b) is compared, and at least one of the main component frequencies of the upper and lower rotating bodies (14a, 14b) is compared. A rotation failure monitoring device for a rotating body in a processing facility, comprising: a rotation failure determination unit (45) that determines rotation failure of upper and lower rotation bodies based on a level . The rotation failure determination unit (45) is configured such that the difference between the principal component frequencies of the upper and lower rotating bodies (14a, 14b) is outside a predetermined range, and the level of the frequency component level is lower than the principal component frequency level. ratio in the case of exceeding a predetermined ratio, rotation defect monitoring device of the rotating body in the processing equipment according to claim 1, wherein determining that rotation failure. The rotating bodies (14a, 14b) are configured such that a roller (101) is rotatably provided on a roller shaft (107), a passage is provided in an axial direction from one end of the roller shaft (107), and further communicated with the passage. And providing a passage in the radial direction, a portion for opening and closing the opening in the circumferential direction on the inner peripheral surface of the roller facing the opening of the passage provided in the radial direction,
A pipe (122) for applying gas pressure is connected to the opening at the axial end of the passage provided in the axial direction, and a pressure detection device (123) is connected to the pipe,
2. The rotation failure monitoring apparatus for a rotating body in a processing facility according to claim 1, wherein the frequency detection unit performs frequency analysis on a pressure change signal detected by the pressure detection apparatus.   The rotation of the rotating body according to any one of claims 1 to 3, wherein the workpiece is a long bar and the processing equipment is a finishing block mill (7) or a sizing mill (8) subsequent thereto. Defect monitoring device. In the rotation failure monitoring method for a rotating body in a processing facility provided with a pair of upper and lower rotating bodies that are rotated in contact with the workpiece or rotated to send the workpiece,
It said upper and lower signal time-varying depending on the rotation angle of the rotating body to detect respectively, the signal of the upper and lower rotary bodies each with frequency analysis determined the frequency component of the signal, each of the upper and lower rotary bodies Rotation of a rotating body in a processing facility, wherein the rotation failure of the upper and lower rotating bodies is determined based on at least the level of one main component frequency of the upper and lower rotating bodies Defect monitoring method. Rotation failure is determined when the difference between the main component frequencies of the upper and lower rotating bodies is outside the predetermined range and the level ratio of the low frequency component level to the main component frequency level exceeds a predetermined ratio. poor rotation monitoring method of a rotating body according to claim 5, characterized in that the.

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