JP2010005688A - Method of determining condition of bearing of table roller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of surely determining the conditions of the bearings of a table roller. <P>SOLUTION: In the method, lubricants S which are discharged from the bearings 12 of the table roller are detected by sensors 17 or further sensors and the conditions of the bearings 12 are determined on the basis of the conditions of the detected lubricant S. One or more of the flow rate, either or more of the concentration of iron content and the concentration of water content of the lubricant are detected by the sensor for detecting the conditions of the lubricants and, by comparing them with a predetermined threshold value, the conditions of the bearing are determined. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a table roll bearing state determination method.

  For convenience of explanation, here, a case of a table roll bearing in a hot rolling line will be described as an example. The hot rolling is generally performed by heating a slab-like metal material produced by continuous casting, ingot-making, or ingoting to several hundred to several hundreds of degrees Celsius in a heating furnace, and then on the hot rolling line. This is a process in which the roll is rotated while being pinched by a pair or a plurality of pairs of rolls, and is rolled thinly and wound into a coil shape.

  FIG. 2 shows an example of a hot rolling line 100 that has been conventionally used. A metal material having a thickness of 140 to 300 mm heated to several hundred to several hundreds of degrees Celsius by the heating furnace 1 (hereinafter referred to as a material to be rolled. It is rolled to a thickness of 0.8 to 25 mm by the rolling mill 3 and thinly extended into a metal strip shape. Then, the water is cooled to a desired temperature by the cooling equipment 26 and then wound by the winding equipment 4.

  In the case of the hot rolling line 100 shown in FIG. 2, the rough rolling mill 2 has three groups R1 to R3, but the number of bases is not necessarily limited thereto.

  Although there is a difference in these radixes, the roughing mill 2 performs rough rolling by reciprocating rolling, one-way rolling, or both, and supplies the material 6 after rough rolling to the finishing mill 3 that follows it. In some cases, a width press is installed immediately upstream of the roughing mill 2.

  In the case of the hot rolling line 100 shown in FIG. 2, the number of rolling mills (stands) constituting the finish rolling mill 3 is seven of F1 to F7, but there are six. Reference numeral 19 denotes a work roll.

  In addition, the hot rolling line 100 is provided with a large number (more than one hundred) of table rolls 5 between other rolling mills (stands) except between the stands of the finishing mill 3. The rolled material 6 is conveyed.

  In addition, when the material 6 is extracted from the heating furnace 1, oxide layers (hereinafter referred to as scales) are formed on the front and back surfaces of the material 6, rolled and thinned, and the temperature is lowered by heat radiation. However, since the material to be rolled 6 is exposed to the atmosphere at a high temperature, new scales are generated on the front and back surfaces of the material 6 to be rolled. For this reason, on the entry side of each rolling mill constituting the rough rolling mill 2, descaling is performed by spraying high-pressure water inside and outside 10-30 MPa on the front and back surfaces of the material 6 to be rolled as the supply pressure from the pump. A device 7 is installed to remove the scale.

  Reference numeral 18 denotes a crop shear which cuts and removes the crop at the leading end of the material 6 to be rolled (finished portion of the leading end of the material 6 to be distorted) before finishing rolling, and smoothly finishes the finish rolling mill 3. Shape into a substantially rectangular planar shape that is easy to bite.

  50 is a control device, 70 is a process computer, and 90 is a business computer.

  FIG. 3 shows the arrangement of devices around the table roll 5. The table roll 5 is cooled by the cooling water w supplied from the cooling water header 10 for the purpose of protection from the radiant heat generated by the material 6 to be rolled. For the sake of convenience, the material to be rolled 6 is depicted as seen through.

  FIG. 4 shows a cross-sectional view of the bearing 12 of the table roll 5. A lubricant (usually oil or grease) is supplied from the pipe 13 toward the bearing 12 for the purpose of lubricating the bearing 12. In the figure, 8 is a bearing box, and 14 is a nozzle for injecting cooling water w.

There are few prior arts related to utility supply for table roll bearings, and there is only a thing like Patent Document 1 that cools a bearing box with cooling air as related to continuous casting rather than hot rolling. .
Japanese Patent Laid-Open No. 2003-290891

  Now, the cooling water w supplied from the cooling water header 10 as shown in FIG. 4 or the water that flows from the material to be rolled 6 after being sprayed from the descaling device 7 to the front and back surfaces of the material 6 to be rolled, not shown. However, it may travel through the table roll 5 and enter the bearing 12, and at this time, if the lubricant S in the bearing 12 is little or cut, the bearing 12 will be burned and damaged.

  Therefore, when an example of the lubricant supply system is shown in FIG. 5, conventionally, the operating state of the distribution valve 16 in the middle of the lubricant supply system or the sensor 17 installed on the inlet side of the supply port 11 of the bearing 12 is used. The lubrication state was judged.

  However, in this conventional method, it cannot be guaranteed that the lubricant is reliably supplied into the bearing 12.

  For example, as shown in FIG. 6, when the attachment portion 15 of the pipe 13 to the supply port 11 of the bearing 12 is detached from the supply port 11, the lubrication state of the bearing 12 becomes abnormal. Nevertheless, the conventional method has a problem that the sensor 17 determines that the lubrication state of the bearing 12 is normal and cannot prevent an accident that the bearing 12 is burned and damaged.

  The present invention has been made to solve such problems as in the prior art, and an object of the present invention is to provide a method capable of reliably determining the state of a table roll bearing.

That is, the present invention is as follows.
(1) A method for determining a bearing state of a table roll, wherein a state of the lubricant discharged from the bearing of the table roll is detected by a sensor, and the state of the bearing is determined based on the detected state of the lubricant. .
(2) The sensor that detects the state of the lubricant is a sensor that detects any one or more of the flow rate, iron concentration, and moisture concentration of the lubricant, and the value detected by the sensor is predetermined. The bearing state determination method for the table roll according to (1), wherein the bearing state is determined by comparing with a threshold value.
(3) When the value detected by the sensor that detects the state of the lubricant is the flow rate of the lubricant, if the flow rate is equal to or less than a predetermined threshold value, it is determined that the lubrication state of the bearing is abnormal, If the value exceeds the threshold value, it is determined that the state of the bearing is normal, and if the value detected by the sensor that detects the state of the lubricant is the iron concentration or moisture concentration of the lubricant, the iron concentration or moisture concentration is The method of determining the bearing state of the table roll according to (2), wherein if it is equal to or greater than a predetermined threshold value, the bearing state is determined to be abnormal, and if it is less than the threshold value, the bearing state is determined to be normal. .
(4) The state of the lubricant supplied to the table roll bearing and the state of the lubricant discharged from the table roll bearing are detected by a sensor, and the detected state is supplied to the detected table roll bearing. A bearing state determination method for a table roll, wherein the bearing state is determined based on a difference between a lubricant state and a lubricant state discharged from the table roll bearing.
(5) The sensor that detects the state of the lubricant is a sensor that detects any one or more of the flow rate, iron concentration, and moisture concentration of the lubricant, and the bearing of the table roll detected by the sensor The condition of the bearing is determined by comparing the difference between the value of the supplied lubricant and the value of the lubricant discharged from the bearing of the table roll with a predetermined threshold value. (4) The bearing state determination method of the table roll as described in (4).
(6) When the value detected by the sensor that detects the state of the lubricant is the flow rate of the lubricant, the flow rate of the lubricant supplied to the bearing of the table roll and the exhaust from the bearing of the table roll If the difference from the lubricant flow rate is greater than or equal to a predetermined threshold value, the bearing state is determined to be abnormal, and if the difference is less than the threshold value, the bearing state is determined to be normal and the sensor detects the lubricant state. Is the iron concentration or moisture concentration of the lubricant, the iron concentration or moisture concentration of the lubricant supplied to the table roll bearing and the lubricant discharged from the table roll bearing. (5) characterized in that the bearing state is determined to be abnormal if the difference from the iron concentration or moisture concentration is greater than or equal to a predetermined threshold value, and that the bearing state is determined to be normal if the difference is less than the threshold value. Record Bearing condition determining method of the table roll.

  ADVANTAGE OF THE INVENTION According to this invention, the method which can determine the state of the bearing of a table roll reliably can be provided.

  An example of an embodiment of the present invention will be described with reference to FIG. Here, the lubricant S of the bearing 12 is grease. The lubricant S is distributed from the pipe 13 by the distribution valve 16 and supplied to the two bearing housings 8 and the bearing 12.

The operating status of the distribution valve 16 is sent to a control device 50 and a process computer 70 (not shown).
The distribution valve 16 may be provided with a sensor 17A for monitoring the operation status, and information related to the operation status may be sent to the control device 50 and the process computer 70 (not shown).

  The lubricant S is pressurized by a pump (not shown) and supplied through the pipe 13. Then, after the lubricant S is supplied into the bearing 12, it is discharged outside the bearing 12 and the bearing housing 8 through the sensor 17.

  When the new lubricant S is supplied into the bearing 12, the old lubricant S in the bearing 12 is pushed out and discharged out of the bearing 12 and the bearing housing 8.

(Embodiment 1)
The present invention primarily detects the state of the lubricant discharged from the bearing by a sensor, and determines the state of the bearing based on the detected state of the lubricant.

  In addition to the case where the lubricant S is supplied to the plurality of bearings 12 via the distribution valve 16 as shown in FIG. 1, unlike the case shown in FIG. The present invention can be similarly applied to the case where each bearing 12 is supplied.

(Embodiment 2)
As the sensor 17 that detects the state of the lubricant S, a sensor that detects at least one of the flow rate of the lubricant S, the iron concentration, and the moisture concentration can be used.

  As a sensor for detecting the flow rate of the lubricant S, for example, a volumetric flow meter for oil such as a roots type, and as a sensor for detecting the iron concentration, for example, an iron-in-oil concentration meter such as an electromagnetic induction type, the above moisture As a sensor for detecting the concentration, for example, a water concentration meter in oil such as a vaporization method or a volumetric method can be used, but it is not limited to these.

  In addition, in the case where the moisture or iron concentration of the lubricant S such as the discharged grease is detected, it is possible to determine the damaged state including the determination of the deterioration state with time in addition to the lubrication state of the bearing 12. The replacement time of the bearing 12 can also be determined.

  For example, the flow rate of the lubricant S is detected by the sensor 17 installed in the pipe 13 passing through the lubricant S on the exit side of the bearing 12 in the direction B in which the lubricant S is supplied and discharged, and the flow rate Q is If a certain value Qa or less, that is, the following expression (1) is satisfied, for example, as shown in FIG. 6 described above, the attachment portion 15 of the pipe 13 to the supply port 11 of the bearing 12 is removed from the supply port 11. The lubricant is not supplied to the bearing 12, and the lubrication state of the bearing 12 is determined to be abnormal. On the other hand, if the value exceeds a certain value Qa, that is, the following expression (1) is not satisfied, it can be determined that the lubrication state of the bearing 12 is normal.

Q ≦ Qa (1)
Further, for example, the sensor 17 installed in the pipe 13 passing through the lubricant S on the exit side of the bearing 12 in the direction B in which the lubricant S is discharged detects the iron concentration of the lubricant S, and the iron concentration D However, if the value Da exceeds a certain value Da, that is, the following expression (2) is satisfied, it is determined that the lubrication state and the damage state of the bearing 12 are abnormal. On the other hand, if it is less than a certain value Da, that is, the following equation (2) is not satisfied, it can be determined that the lubrication state and the damage state of the bearing 12 are normal.

D ≧ Da (2)
Further, for example, the moisture concentration of the lubricant S is detected by the sensor 17 installed in the pipe 13 passing through the lubricant S on the exit side of the bearing 12 when viewed in the direction B in which the lubricant S is discharged. However, if a certain value Ea or more, that is, the following expression (3) is satisfied, it is determined that the lubrication state and the damage state of the bearing 12 are abnormal. On the other hand, if it is less than a certain value Ea, that is, if the following formula (3) is not satisfied, it can be determined that the lubrication state and the damage state of the bearing 12 are normal.

E ≧ Ea (3)
Furthermore, for example, it is conceivable to detect the oil concentration of the lubricant S such as grease discharged from the bearing. However, according to the present invention, water that flows from the material to be rolled 6 after being sprayed mainly from the descaling device 7 to the front and back surfaces of the material to be rolled 6 enters the bearing 12 through the table roll 5 and enters the bearing 12. It is intended to detect that the lubricant S is running out or running out. Therefore, if the moisture concentration in the lubricant S discharged from the bearing 12 is high, this means that the oil concentration in the lubricant S is low, and the oil concentration is detected only by detecting the moisture concentration. The same effect can be obtained.

(Embodiment 3)
As described above, when the flow rate of the lubricant S such as the discharged grease is detected, the lubrication state of the bearing 12 can be determined.

  Further, when the moisture or iron concentration of the lubricant S such as the discharged grease is detected, it is possible to determine the damaged state including the determination of the lubrication state of the bearing 12 and the deterioration state over time. I also mentioned earlier.

  Then, when the value detected by the sensor that detects the state of the lubricant S is the flow rate of the lubricant S, the flow rate satisfies, for example, the above-described formula (1), that is, predetermined. If it is below the threshold value, it is determined that the lubrication state of the bearing 12 is abnormal and does not satisfy the above-mentioned formula (1), that is, if the above-described threshold value is exceeded, it is determined that the lubrication state of the bearing 12 is normal. When the value detected by the sensor that detects the state of S is the iron concentration or moisture concentration of the lubricant S, the iron concentration or moisture concentration satisfies, for example, the above-described formula (2) or (3). That is, if it is equal to or greater than a predetermined threshold value, it is determined that the state of lubrication and damage of the bearing 12 is abnormal, and if the above formula (2) or (3) is not satisfied, that is, if it is less than the above threshold value, 12 lubrication and damage conditions Normal and judges so on, the kind of determining the state can be changed to depending on the type of sensor.

(Embodiment 4)
In the present invention, the state of the lubricant S supplied to the bearing 12 and the state of the lubricant S discharged from the bearing 12 are detected by a sensor, and the detected state of the lubricant S supplied to the bearing 12 is detected. The state of the bearing 12 can also be determined based on the difference from the state of the lubricant S discharged from the bearing 12.

(Embodiment 5)
Unlike FIG. 1, when the lubricant S is supplied directly to the respective bearings 12 without going through the distribution valve 16, for example, the supply of the lubricant S and the direction B in which the lubricant 12 is discharged are considered. The flow rate of the lubricant S is different between the sensor 17A installed in place of the distribution valve 16 in each pipe 13 passing through the lubricant S on the inlet side and the sensor 17 installed on the outlet side of the bearing 12 in the same direction B. Is detected. Then, the difference between the flow rate _{Q EXIT} side out with the flow rate _{Q ENT} the inlet side is a certain value Qb or more, i.e., satisfies the following formula (4-1), lubrication of the bearing 12 is judged to be abnormal If it is less than a certain value, that is, if the following equation (4-1) is not satisfied, it can be determined that the lubrication state of the bearing 12 is normal. Here, as the sensor 17A, the same sensor as the sensor 17 can be used.

Q _ENT -Q _EXIT ≧ Qb (4-1)
As described above, when a value less than a certain value Qb is added as a determination condition, the actual lubricant S can be adjusted by adjusting the value of Qb even when there is a sensor error or a change in characteristics over time. Therefore, it is possible to prevent troublesomeness that reacts to slight fluctuations in the flow rate and determines that it is abnormal.

Alternatively, in the case shown in FIG. 1, the flow rate Q _ENT lubricant S detected by the sensor 17A of the attached to the dispensing valve 16, the flow rate Q _ENT × .alpha.i multiplied by a certain distribution ratio .alpha.i which are determined in each bearing 12 each The flow rate Q _EXIT i of the lubricant S detected by the sensor 17 installed in the pipe 13 passing through the lubricant S on the outlet side of each corresponding bearing 12 is less than a certain value Qb, If the expression (4-2) is satisfied, it is determined that the lubrication state of the bearing 12 that is less than the certain value Qb is abnormal, and if it is less than the certain value, that is, the following expression (4-2) is not satisfied, the bearing 12 is satisfied. It can also be determined that the lubrication state is normal.

Q _ENT × αi-Q _EXIT i ≧ Qb (4-2)
In addition, for example, the sensor 17A installed in the pipe 13 passing through the lubricant S on the entry side of the bearing 12 as viewed in the direction B in which the lubricant S is supplied and discharged, and installed on the exit side of the bearing 12 as seen in the same direction B The sensor 17 detects the iron concentration of the lubricant S, and the difference between the iron concentration D _ENT on the entry side and the iron concentration D _EXIT on the exit side is a certain value Db or more, that is, the following formula (5) ), The lubrication state and damage state of the bearing 12 are determined to be abnormal. On the other hand, if it is less than a certain value, that is, if the following formula (5) is not satisfied, it can be determined that the lubrication state and the damage state of the bearing 12 are normal.

D _EXIT -D _ENT ≧ Db (5)
In addition, for example, the sensor 17A installed in the pipe 13 passing through the lubricant S on the entry side of the bearing 12 as viewed in the direction B in which the lubricant S is supplied and discharged, and installed on the exit side of the bearing 12 as seen in the same direction B The sensor 17 detects the moisture concentration of the lubricant S. The difference between the moisture concentration E _ENT on the entry side and the iron concentration E _EXIT on the exit side is equal to or greater than a certain value Eb, that is, the following formula (6 ), The lubrication state and damage state of the bearing 12 are determined to be abnormal. On the other hand, if it is less than a certain value, that is, the following equation (6) is not satisfied, it can be determined that the lubrication state and the damage state of the bearing 12 are normal.

E _EXIT −E _ENT ≧ Eb (6)
(Embodiment 6)
As described above, when the flow rate of the lubricant S such as the discharged grease is detected, the lubrication state of the bearing 12 can be determined.

  Further, as described above, when the concentration of the moisture and iron content of the lubricant S such as the discharged grease is detected, it is possible to determine the lubrication state and the damage state of the bearing 12.

  Then, when the value detected by the sensor that detects the state of the lubricant S is the flow rate of the lubricant S, the flow rate satisfies, for example, the above-described formula (4), that is, predetermined. If it is equal to or greater than the threshold value, it is determined that the lubrication state of the bearing 12 is abnormal, and the above-described equation (4) is not satisfied, that is, if it is less than the above-described threshold value, the lubrication state of the bearing 12 is determined to be normal. When the value detected by the sensor for detecting the state of the agent S is the iron concentration or the moisture concentration of the lubricant S, the iron concentration or the moisture concentration is, for example, the above-described equation (5) or (6). If satisfied, that is, if it is greater than or equal to a predetermined threshold value, it is determined that the state of lubrication and damage of the bearing 12 is abnormal, and does not satisfy the above expression (5) or (6), that is, if it is less than the above threshold value. If the bearing 12 is lubricated and damaged Condition is determined to be normal, so on, can also change the type of the determined state depending on the type of sensor.

  As described above, the description of the above embodiment is merely an example, and the present invention is not limited thereto. For example, the lubricant S is not limited to a solid lubricant such as grease, and the present invention can be applied without any trouble even when it is a liquid lubricant such as oil.

  Moreover, although the description of the above embodiment has been described by taking the case of a table roll bearing in a hot rolling line as an example, the present invention is not limited to this, for example, a table roll bearing in a continuous casting line The same applies to the above.

  Or the attachment part 15 to the supply port 11 of the bearing 12 of the piping 13 has come off from the supply port 11 and the lubricant is not supplied to the bearing 12 as in the example in the above embodiment. The present invention is not limited to the case, and the present invention is exactly the same as the method in the above embodiment even when the pipe 13 is closed or the pipe 13 is cracked and the lubricant S leaks out. The state of the bearing 12 can be determined by the method.

  In the above embodiment, the difference between the value of the lubricant supplied to the table roll bearing detected by the sensor and the value of the lubricant discharged from the table roll bearing is determined in advance. In comparing with the threshold value, the difference between the two is taken. However, if the order of the subtracted value and the subtracted value is reversed, the direction of the inequality sign is reversed. Since it is substantially the same as the form, it falls within the scope of the present invention.

  Furthermore, instead of taking the difference between the two, a ratio may be taken and compared with a predetermined threshold value, in which case the value of the lubricant supplied to the bearing of the table roll Either of the values of the lubricant discharged from the same bearing of the table roll can be taken as the denominator, and either can be taken as the numerator, but the inequality sign that is theoretically determined depending on whether it is abnormal or normal It is necessary to set the orientation, and such a case also falls within the scope of the present invention.

  However, in any case, according to the present invention, since the lubricant S discharged from the bearing 12 is detected by the sensor 17 or the sensor 17A, the lubrication state of the bearing 12 is determined. As shown in FIG. 6, the attachment portion 15 of the pipe 13 to the supply port 11 of the bearing 12 is detached from the supply port 11, and the lubricant S is not supplied to the bearing 12. Even so, it is possible to determine this, and it is possible to prevent an accident in which the bearing 12 is burned and damaged.

  In addition, when the moisture or iron content of the discharged lubricant S is detected, for example, it is possible to determine not only the lubrication state of the bearing 12 but also the damage state including the determination of the deterioration state over time, and the replacement of the bearing 12 is possible. Since it is possible to determine the timing, there is also an advantage that the repair costs associated with the accident can be reduced.

It is a diagram for demonstrating an example of embodiment of this invention. It is a diagram for demonstrating the whole hot rolling line outline | summary. It is a diagram for explaining table roll peripheral equipment. It is sectional drawing of the bearing of a table roll. It is a diagram for demonstrating the bearing lubrication state determination method of the conventional table roll. It is a diagram for demonstrating the problem of a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Heating furnace 2 Coarse rolling mill 3 Finish rolling mill 4 Winding equipment 5 Table roll 6 Rolled material 7 Descaling device 8 Bearing box 9 Motor 10 Cooling water header 11 Supply port 12 Bearing 13 Piping 14 Nozzle 15 Mounting part 16 Distribution valve 17, 17A Sensor 18 Crop shear 19 Work roll 19A Backup roll 20 Looper 21 Finishing side thermometer 22 Finishing side thickness gauge 23 Runout table 25 Winding equipment inlet side thermometer 26 Cooling equipment 50 Control device 70 Process computer 90 Business computer DESCRIPTION OF SYMBOLS 100 Hot rolling line w Cooling water A The conveyance direction of the to-be-rolled material 6 B The direction where the lubricant S is supplied (discharged) S Lubricant

Claims (6)

A method for determining a bearing state of a table roll, comprising: detecting a state of lubricant discharged from the bearing of the table roll by a sensor; and determining the state of the bearing based on the detected state of the lubricant. The sensor that detects the state of the lubricant is a sensor that detects at least one of the flow rate, iron concentration, and moisture concentration of the lubricant, and compares the value detected by the sensor with a predetermined threshold value. The bearing state determination method for a table roll according to claim 1, wherein the state of the bearing is determined by doing so. If the value detected by the sensor that detects the state of the lubricant is the flow rate of the lubricant, the lubrication state of the bearing is determined to be abnormal if the flow rate is equal to or less than a predetermined threshold value, and the value exceeds the threshold value. If it is determined that the lubrication state of the bearing is normal, and the value detected by the sensor that detects the state of the lubricant is the iron concentration or moisture concentration of the lubricant, the iron concentration or moisture concentration is determined in advance. The method of determining a bearing state of a table roll according to claim 2, wherein if it is equal to or greater than a predetermined threshold value, the bearing state is determined to be abnormal, and if it is less than the threshold value, the bearing state is determined to be normal. The state of the lubricant supplied to the table roll bearing and the state of the lubricant discharged from the table roll bearing are detected by a sensor, and the detected lubricant supplied to the table roll bearing is detected. A method for determining a bearing state of a table roll, comprising: determining a bearing state based on a difference between the state and a state of a lubricant discharged from the bearing of the table roll. A sensor that detects the state of the lubricant is a sensor that detects any one or more of the flow rate, iron concentration, and moisture concentration of the lubricant, and is supplied to the bearing of the table roll detected by the sensor. 5. The state of the bearing is determined by comparing the difference between the value of the lubricant and the value of the lubricant discharged from the table roll bearing with a predetermined threshold value. The bearing condition determination method of the table roll as described in 2. When the value detected by the sensor that detects the state of the lubricant is the flow rate of the lubricant, the flow rate of the lubricant supplied to the bearing of the table roll and the lubricant discharged from the bearing of the table roll If the difference from the flow rate is greater than or equal to a predetermined threshold value, the bearing lubrication state is determined to be abnormal, and if the difference is less than the threshold value, the bearing state is determined to be normal and detected by a sensor that detects the lubricant state. When the obtained value is the iron concentration or moisture concentration of the lubricant, the iron concentration or moisture concentration of the lubricant supplied to the table roll bearing and the iron concentration of the lubricant discharged from the table roll bearing The bearing state is determined to be abnormal if the difference from the moisture concentration is greater than or equal to a predetermined threshold value, and if the difference is less than the threshold value, the bearing state is determined to be normal. Bearing condition determining method of the table roll.

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