JP2018016848A - Cleaning method of roll and roll cleaning device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cleaning method of a roll and a roll cleaning device, capable of cleaning the roll with passing an object material continuously while preventing generation of product failure just after cleaning.SOLUTION: There is provided a cleaning method of a roll gotten in contact with a steel sheet after adhesion of a treatment liquid in a continuous treatment line in which the treatment liquid is adhered to the steel sheet, at least a part of a surface of the roll between a contact end part where contact of the steel sheet with the roll is ended and a contact initiation part where contact of the steel sheet with the roll is initiated is covered with a cleaning cover, and drainage in the cleaning cover is aspirated while discharging the cleaning liquid to a surface of the roll within the cleaning cover.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a roll cleaning method and a roll cleaning apparatus that can clean the surface of a roll that comes into contact with a steel plate without causing product defects even during the passage of the steel plate.

  In the iron making process, chemical conversion treatment is widely performed in which various surface treatment liquids (hereinafter, also simply referred to as “treatment liquid”) such as a lubricity improver are adhered to the surface of a steel sheet. In the chemical conversion treatment section, the steel plate to which the surface treatment liquid is attached is conveyed using various steel plate contact rolls (hereinafter also simply referred to as “rolls”). At this time, the steel sheet and the roll come into contact with each other, and the surface treatment liquid is transferred from the back surface (or sometimes the surface) of the steel plate in contact with the roll to the surface of the roll. As the steel sheet continues to be conveyed, the surface treatment liquid is accumulated in layers on the surface of the roll.

  When the layer of the treatment liquid is accumulated on the surface of the roll, a phenomenon occurs in which the surface treatment liquid is reversely transferred from the surface of the roll to the back surface of the steel sheet together with the transfer described above. The amount of treatment liquid transferred from the steel sheet to the roll and the amount of reverse transfer of the treatment liquid from the roll to the steel sheet vary depending on the amount of treatment liquid deposited on the surface of the roll, so the target material (the steel sheet that will be the final product) The surface treatment liquid is uneven on the back surface of the steel plate between the plates. Specifically, since the amount of treatment liquid adhering to the surface of the roll is small at the beginning of threading, the amount of treatment liquid transferred from the steel sheet to the roll is relatively large, and the amount of treatment liquid on the back surface of the steel sheet on the exit side of the roll The amount of adhesion is reduced. On the other hand, after a predetermined time has passed after passing the plate, a large amount of processing liquid is attached to the surface of the roll, and the transfer amount is relatively small. The amount of treatment liquid attached increases. In particular, when the processing amount of the target material in one cycle in which the sheet is continuously passed is large, the unevenness of the steel plate surface within one cycle becomes large. It is desirable to clean the roll during the cycle so that it is uniform.

  Patent document 1 is mentioned as a literature indicated about the washing mechanism in the chemical conversion treatment section of a steel plate. Patent Document 1 discloses an apparatus for continuously cleaning oil on both surfaces of a steel sheet by applying a mediating substance to both surfaces of the steel sheet and performing a cavitation process in which ultrasonic waves are applied via the mediating substance.

  Further, Patent Document 2 is cited as a document that discloses a mechanism for cleaning a roll to which a chemical solution is attached. In Patent Document 2, in order to clean the filth caused by the chemical liquid of the roll that comes into contact with the continuous sheet to which the chemical liquid is applied, a fluid containing filth such as paper powder removed while jetting high-pressure fluid onto the roll is sucked. Is disclosed.

JP 2014-65970 A JP 2013-13433 A

  The invention described in Patent Document 1 requires that a mediator for ultrasonic cleaning is applied to the surface of the steel sheet. However, it is difficult to apply a technique for providing such a mediator to the cleaning of a roll.

  Moreover, there is a problem in applying the roll cleaning technique as in Patent Document 2 to the cleaning of the roll in the chemical conversion treatment section of the steel sheet. The reason is that the amount of surface treatment liquid attached to the roll (transfer amount) from the steel plate to the roll and the amount of surface treatment liquid attached from the roll to the steel plate (reverse transfer amount) are within a predetermined balance during the passing of the steel plate. However, if the surface of the roll is completely washed with high-pressure water or the like, the balance between the transfer amount and the reverse transfer amount is lost, and the transfer amount relatively increases immediately after the roll is washed. The adhesion amount of the surface treatment liquid on the rear surface of the steel sheet is extremely reduced, and a defective steel sheet is produced.

  In order to prevent the occurrence of product defects immediately after cleaning the roll, conventionally, the roll of the target material is not cycled while the target material (steel plate that is the final product) is being passed, and the target material passing cycle is completed. After that, the roll cleaning operation is performed by scraping off the treatment liquid layer on the surface of the roll using a doctor blade or the like while passing a dummy plate material (a steel plate that is not the final product).

  However, this method has a problem that the production efficiency of the line is lowered because the target material cannot be passed while the dummy plate material is being passed.

  The present invention has been completed in view of the above problems, and is capable of cleaning a roll while continuously passing a target material while preventing the occurrence of product defects immediately after cleaning. It is an object of the present invention to provide a cleaning method and a roll cleaning device.

Means for solving the above problems are as follows.
[1] In a continuous processing line for attaching a treatment liquid to a steel plate, a cleaning method for a roll that comes into contact with the steel plate after the treatment liquid adheres, from the contact end portion where the steel plate finishes contact with the roll, Covering at least a part of the surface of the roll with the cleaning cover until the steel plate starts contact with the roll, while discharging the cleaning liquid to the surface of the roll inside the cleaning cover A method of cleaning a roll for sucking the drainage liquid in the cleaning cover.
[2] The roll cleaning method according to [1], wherein the adhesion amount of the treatment liquid on the surface of the roll in the subsequent stage of the cleaning cover is adjusted by controlling the suction pressure of the drainage liquid in the cleaning cover.
[3] The roll cleaning method according to [1] or [2], wherein a treatment liquid or water is applied to the surface of the roll at a stage subsequent to the cleaning cover and before the contact start portion.
[4] By analyzing the waste liquid, the amount of the treatment liquid detached from the surface of the roll by cleaning is calculated, and an amount of the treatment liquid or water corresponding to the amount of the detached treatment liquid is applied [3] ] The cleaning method of the roll as described in.
[5] In a continuous processing line for attaching the treatment liquid to the steel plate, a roll cleaning device for cleaning a roll that comes into contact with the steel plate after the treatment liquid adheres, wherein the steel plate finishes contact with the roll. A cleaning cover that covers at least a part of the surface of the roll, and a surface of the roll that is provided between the steel plate and the contact start portion where the steel sheet starts to contact the roll. A roll cleaning apparatus, comprising: a cleaning liquid discharging unit that discharges the cleaning liquid toward the surface; and a suction unit that is provided inside the cleaning cover and sucks the drained liquid.
[6] The roll cleaning apparatus according to [5], wherein the suction unit is capable of controlling the suction pressure so as to adjust the amount of the treatment liquid attached to the surface of the roll in the subsequent stage of the cleaning cover.
[7] The roll cleaning according to [5] or [6], further including an application unit that applies a treatment liquid or water to the surface of the roll at a stage subsequent to the cleaning cover and before the contact start portion. apparatus.
[8] The roll cleaning apparatus according to [7], wherein the application unit applies an amount of the processing liquid or water according to the amount of the processing liquid detached from the surface of the roll by cleaning.

  According to the present invention, it is possible to clean the surface of the roll while passing the target material without causing product defects immediately after cleaning.

FIG. 1 is an explanatory view showing an example of a method for cleaning a roll according to the present invention. FIG. 2 is an explanatory view showing another example of the roll cleaning method of the present invention.

  The roll cleaning method of the present invention will be described with reference to FIG.

  As shown in FIG. 1, the roll cleaning method according to the present invention uses a roll 1 in contact with a steel plate and a roll cleaning device 2 for cleaning the surface of the roll 1.

  In the example of FIG. 1, a steel plate 3 is wound around the surface of the roll 1. More specifically, the steel plate 3 that has been passed toward the roll 1 is wound around the surface of the roll 1, changes its traveling direction by about 90 °, and comes out in the exit direction of the roll 1. In this case, a position where the steel plate 3 starts to be wound on the roll 1 is defined as a contact start portion 11a, and a position where the steel plate 3 finishes being wound on the roll 1 is defined as a contact end portion 11b.

  Although not shown in FIG. 1, on the entry side (lower side of the drawing) of the roll 1, equipment for attaching various treatment liquids such as a lubrication improver to the front and back surfaces of the steel plate 3 is provided. Therefore, the steel plate 3 comes into contact with the roll 1 with the treatment liquid applied to the front and back surfaces. In addition, in the example of FIG. 1, the surface of the steel plate which contacts the roll 1 is made into the back surface 3b, and the surface which is not so is made into the surface 3a.

  When the surface of the roll 1 is clean, the treatment liquid is applied from the back surface 3b of the steel plate 3 to the surface of the roll 1 while the steel plate 3 is wound around the roll 1, that is, between the contact start portion 11a and the contact end portion 11b. Is transcribed. Therefore, at the beginning of passing the steel plate 3, the amount of the treatment liquid adhering to the back surface 3b of the steel plate 3 is smaller on the exit side of the contact end portion 11b than on the entrance side of the contact start portion 11a. ing.

  While the steel plate 3 is being passed, the treatment liquid transferred from the back surface 3 b of the steel plate 3 gradually accumulates on the surface of the roll 1. When the amount of treatment liquid deposited on the surface of the roll 1 increases, reverse transfer in which the treatment liquid adheres from the surface of the roll 1 to the back surface of the steel plate 3 occurs between the contact start portion 11a and the contact end portion 11b. Become. The transfer amount from the steel plate 3 to the roll 1 and the reverse transfer amount from the roll 1 to the steel plate 3 depend on the relationship between the treatment liquid adhesion amount on the back surface of the steel plate 3 and the treatment liquid adhesion amount on the roll 1 surface, respectively. Determined. The amount of transfer tends to be relatively large while the amount of treatment liquid deposited on the surface of the roll 1 is small, and the amount of reverse transfer is relatively large while the amount of deposit of treatment liquid on the surface of the roll 1 is large. Tend to be.

  The roll cleaning device 2 is provided in a region of the surface of the roll 1 where the steel plate 3 is not in contact (between the contact end portion 11b and the contact start portion 11a). The roll cleaning device 2 includes a cleaning cover 2a, a cleaning liquid discharge unit 2b, and a suction unit 2c. The cleaning liquid discharge means 2b and the suction means 2c are arranged toward the surface of the roll 1 inside the cleaning cover 2a.

  The cleaning cover 2 a is disposed so as to cover at least a part of the roll 1 in the circumferential direction. From the viewpoint of eliminating uneven cleaning in the axial direction of the roll 1, the cleaning cover 2 a covers the entire axial direction of the roll 1, and discharge liquid (cleaning liquid to be described later) uniformly along the axial direction of the roll 1. It is preferable to arrange a plurality of cleaning liquid discharge means 2b in the axial direction so that

  The cleaning liquid discharger 2 b sprays or ejects the cleaning liquid toward the surface of the roll 1. The cleaning liquid has a function of dissolving and removing the processing liquid attached to the surface of the roll 1. Examples of the cleaning liquid include water or a solution obtained by diluting a chemical for dissolving a small amount of processing liquid in water. For example, a commercially available nozzle can be used as the cleaning liquid discharger 2b.

When the cleaning liquid is discharged onto the surface of the roll 1, a waste liquid in which the processing liquid, dirt, dust and the like on the surface of the roll 1 are dissolved is produced. The suction means 2c is provided inside the cleaning cover 2a, and has a function of sucking the drainage produced by the discharge of the cleaning liquid and discharging it to the outside of the cleaning cover 2a. In order to improve the recovery efficiency of the drainage, as shown in FIG. 1, the cleaning liquid discharge means 2b is provided inside the cleaning cover 2a on the inlet side in the rotation direction of the roll 1, and the outlet side in the rotation direction of the roll 1 is provided. It is preferable to provide the suction means 2c. For example, a pump or the like can be used as the suction means 2c. Further, a wiping nozzle can be installed inside the cleaning cover 2a, air can be ejected from the wiping nozzle, and the cleaning liquid / drainage can be discharged to the outside of the cleaning cover 2a by being accompanied by the Coanda effect.

  In the present invention, the cleaning liquid discharge means 2b and the suction means 2c are provided inside the cleaning cover 2a, so that the cleaning liquid discharged from the cleaning liquid discharge means 2b and the waste liquid produced by the cleaning remain in the cleaning cover 2a. Therefore, it is prevented from being scattered to surrounding facilities. Further, since the inside of the cleaning cover 2a is kept in a high humidity state, the drainage produced after cleaning is prevented from drying out on the surface of the roll 1 facing the cleaning cover 2a. The drainage can be reliably recovered through the suction means 2c.

  In FIG. 1, the flow of the cleaning liquid is indicated by dotted arrows. A storage tank 4 for storing the cleaning liquid, a pump 5 for feeding the cleaning liquid, a flow rate adjusting valve 6 and the like are provided in the preceding stage of the cleaning liquid discharging means 2b. Although details will be described later, the storage tank 4 may be provided with a temperature adjusting device 7 having a function of adjusting the temperature of the cleaning liquid. As the temperature adjustment device 7, for example, an underwater heater can be used.

  Further, the drained liquid sucked by the suction means 2 c is accommodated in the drainage tank 9 through the mist trap 8. Further, a mist suction fan 10 is provided at the subsequent stage of the mist trap 8.

  Next, the operation of the present invention will be described.

  When the cleaning liquid is discharged from the cleaning liquid discharge means 2b toward the surface of the roll 1, a part of the processing liquid layer attached to the surface of the roll 1 is washed away. Thereby, about the surface of roll 1, it will be in the state where the amount of adhesion of processing liquid is smaller in the latter part of roll cleaning device 2 than the former part of roll washing device 2. FIG.

  Further, in the subsequent stage of the roll cleaning device 2, a water film is formed on the surface of the roll 1 by applying a cleaning liquid during cleaning. Thereby, after the surface of the roll 1 passes the roll cleaning apparatus 2, when contacting with the back surface of the steel plate 3 between the contact start part 11a and the contact end part 11b, the process of the back surface of the steel plate 3 with a water film Since the degree of contact between the liquid layer and the treatment liquid layer on the surface of the roll 1 is suppressed, the transfer amount of the treatment liquid from the steel plate 3 to the roll 1 and the reverse transfer amount of the treatment liquid from the roll 1 to the steel plate 3 are kept small. be able to. Thus, by discharging the cleaning liquid onto the surface of the roll 1, the treatment liquid layer on the surface of the roll 1 can be peeled off, and the back surface of the steel plate 3 between the contact start portion 11 a and the contact end portion 11 b is removed. Since fluctuations in the amount of the processing liquid can be suppressed, it is possible to prevent the generation of a product with poor quality.

  In the present invention, it is preferable to control the suction pressure of the suction means 2c in the cleaning cover 2a. By adjusting the suction pressure, it is possible to adjust the amount of drained liquid that is collected during cleaning and discharged to the outside of the cleaning cover 2a. The waste liquid that has not been collected remains on the surface of the roll 1 to form a treatment liquid layer. When controlling the suction pressure of the suction means 2c, the discharge amount of the cleaning liquid from the cleaning liquid discharge means 2b can be adjusted according to the suction pressure.

  For example, the phenomenon that the amount of treatment liquid deposited on the surface of the roll 1 temporarily decreases significantly due to cleaning, thereby suppressing the phenomenon that the amount of treatment liquid transferred from the back surface of the steel plate 3 to the roll 1 temporarily increases rapidly. For this purpose, it is preferable that the treatment liquid layer on the surface of the roll 1 is not completely peeled off at the time of washing, but a certain amount of treatment liquid layer remains on the surface of the roll 1 even after washing. In such a case, it is effective to reduce the discharge amount and suction pressure of the cleaning liquid to reduce the amount of the processing liquid component that is detached from the surface of the roll 1 during cleaning. Thus, the amount of the cleaning liquid discharged and the amount of the processing liquid layer remaining on the surface of the roll 1 after cleaning are adjusted by adjusting the amount of the processing liquid component desorbed from the surface of the roll 1 during cleaning. The suction pressure can be adjusted as appropriate.

  Since the treatment liquid is transferred from the back surface of the steel plate 3 to the surface of the roll 1 by contact with the roll 1, the treatment liquid adhesion amount tends to be smaller on the back surface than on the surface of the steel plate 3. If the difference between the front and back surfaces of the treatment liquid adhesion amount is too large, the product quality is poor. Therefore, the discharge amount of the cleaning liquid and the suction force of the drained liquid in the cleaning cover 2a are controlled so that the difference in the amount of the processing liquid adhering to the front and back surfaces is within an allowable range in terms of product quality.

  In addition, depending on the type of the treatment liquid, the surface of the roll 1 after passing through the roll cleaning device 2 is sufficiently sufficiently to reach the contact start portion 11a so as not to inhibit the chemical conversion treatment reaction in the steel plate 3. It may be desirable for the surface to be dry. In order to dry the surface of the roll 1 after cleaning, it is effective to discharge a hot cleaning liquid to the roll 1. Further, there is an effect that the cleaning power can be improved by discharging a high temperature cleaning liquid. More specifically, the cleaning liquid heated by the temperature adjusting device 7 (for example, an underwater heater) may be discharged onto the surface of the roll 1. As an example, from the viewpoint of improving the cleaning power, the temperature of the cleaning liquid during discharge is preferably 100 ° C. or lower, more preferably 80 ° C. or lower, and further preferably 70 ° C. or lower. The lower limit of the temperature of the cleaning liquid is not particularly limited as long as it exceeds 0 ° C. The degree of drying of the surface of the roll 1 after cleaning can also be adjusted by controlling the discharge amount of the cleaning liquid in the cleaning liquid discharge means 2b and the suction pressure in the suction means 2c.

  Next, a method for adhering water or a treatment liquid to the roll surface after completion of the cleaning will be described.

  In this case, although not shown in FIG. 1, a nozzle used as an application means for applying water or a treatment liquid to the roll surface, for example, as a cleaning liquid discharge means 2b, in the subsequent stage of the roll cleaning device 2 and before the contact start portion 11a. The same nozzle may be provided. In order to reduce coating unevenness, it is preferable to apply water or a treatment liquid to the surface of the roll 1 in the form of mist or steam.

  First, an example in which the treatment liquid is applied by the application unit will be described. By applying the treatment liquid, the adhesion amount of the treatment liquid on the surface of the roll 1 is increased. For example, even when the amount of the treatment liquid layer on the surface of the roll 1 is excessively reduced in the upstream roll cleaning device 2, the surface of the roll 1 can be replenished with the subsequent application means. Improperly adjusting the amount of treatment liquid applied to the surface of the roll 1 so that the balance between the transfer amount between the roll 1 and the steel plate 3 and the reverse transfer amount is not significantly lost before and after the cleaning, so that the quality is poor immediately after the cleaning. It is possible to prevent the product to become outflow.

  Next, an example in which water is applied to the surface of the roll 1 using an application unit (not shown) will be described. By applying water, a thin water film is formed on the surface of the treatment liquid layer of the roll 1. When the surface of the roll 1 and the back surface of the steel plate 3 come into contact with each other in this state, the transfer amount of the treatment liquid from the back surface of the steel plate 3 to the surface of the roll 1 or the steel plate 3 from the surface of the roll 1 due to the presence of a water layer. The reverse transfer amount of the processing liquid to the back surface of the substrate can be kept small. Therefore, since the fluctuation | variation of the process liquid amount of the back surface of the steel plate 3 between the contact start part 11a and the contact end part 11b can be suppressed, generation | occurrence | production of the product which becomes a quality defect can be prevented.

  In addition to the water and the treatment liquid described above, a diluted solution obtained by diluting the treatment liquid in water at an appropriate ratio can be applied to the surface of the roll 1 using an application means.

  The coating amount of the treatment liquid, water, and the diluted solution of the treatment liquid described above is such that the difference between the treatment liquid adhesion amount on the steel sheet surface and the treatment liquid adhesion amount on the steel sheet back surface is within an acceptable range in terms of product quality. Adjusted to. Specifically, the thickness of the treatment liquid layer adhering to the back surface of the steel plate 3 on the entry side in the sheet passing direction with respect to the contact start portion 11a is defined as a reference layer thickness. The coating amount can be adjusted using as an index how thick the treatment liquid layer (or water layer) is formed on the surface of the roll 1 in the cover 2a and the contact start portion 11a).

  More specifically, when the treatment liquid is applied by the application means, a treatment liquid layer thickness of 70% or more and 90% or less with respect to the reference layer thickness is formed on the surface of the roll 1. The treatment liquid layer thickness at this time includes not only the treatment liquid newly applied by the application means but also the treatment liquid layer remaining on the surface of the roll 1 after washing with the washing cover 2a. When the ratio of the thickness of the treatment liquid layer on the surface of the roll 1 is smaller than 70%, the transfer amount is relatively large. On the other hand, when the thickness of the treatment liquid layer is larger than 90%, the reverse transfer amount is relatively large. Therefore, it becomes difficult to obtain a steel sheet in which the difference in the amount of the treatment liquid adhering to the front and back surfaces is within a desired range.

  When water is applied, a water layer thickness of 20% or more and 30% or less with respect to the reference layer thickness is formed on the surface of the roll 1. When the water layer thickness is less than 20%, the treatment liquid is excessively transferred from the steel sheet to the roll, and there is a problem that the surface treatment reaction after the roll contact is inhibited. When the water layer thickness exceeds 30%, the concentration of the treatment liquid on the steel sheet However, there is a problem that the chemical conversion reaction of the steel plate is slowed down.

  Furthermore, in order to more precisely control the amount of treatment liquid, water, etc. applied to the roll, the amount of treatment liquid desorbed from the surface of the roll 1 during cleaning is calculated, and the treatment is performed according to the amount of desorption. It is effective to perform feedback control for adjusting the coating amount of liquid, water, or the like. Specifically, as shown in FIG. 1, the amount of drainage recovered in the drainage tank 9 via the mist trap 8 and the concentration of the components of the processing liquid contained in the drainage are analyzed. Thus, it is possible to calculate the mass of the treatment liquid component desorbed from the roll 1 by the cleaning (desorption amount of the treatment liquid). If the amount of the treatment liquid detached from the roll 1 at the time of cleaning is too large, the transfer amount of the treatment liquid from the steel plate 3 to the roll 1 becomes excessive immediately after cleaning. It is preferable to apply the treatment liquid. For example, a treatment liquid (or a dilution liquid of the treatment liquid) containing a component corresponding to 3% by mass or more and 100% by mass or less is applied to the surface of the roll 1 by application means with respect to the amount of the treatment liquid desorbed by cleaning. It is preferable.

  In addition, although the aspect in which the steel plate 3 winds around the roll 1 is described in FIG. 1, the roll 1 of the present invention only needs to be in contact with the steel plate 3 at least in part. For example, as shown in FIG. 2, the roll cleaning method and the roll cleaning apparatus 2 according to the present invention can also be applied to a roll 1 in contact with the steel plate 3. In the example of FIG. 2, the contact start part 11a and the contact end part 11b overlap, but the roll cleaning device 2 is provided in any region other than the contact start part 11a (contact end part 11b), and the roll 1 What is necessary is just to wash | clean the surface of.

  The present invention is used in a continuous processing line in which a steel sheet is passed through a roll after a processing liquid is attached to the steel sheet. A preferred example of the continuous processing line is a hot dip galvanizing line.

  As described above, according to the present invention, the balance between the transfer amount and the reverse transfer amount between the steel plate and the roll is not greatly lost before and after the surface of the roll 1 is cleaned. It is possible to clean the roll while improving the operating rate of the equipment.

DESCRIPTION OF SYMBOLS 1 Roll 2 Roll cleaning apparatus 2a Cleaning cover 2b Cleaning liquid discharge means 2c Suction means 3 Steel plate 3a Steel plate surface 3b Steel plate back surface 4 Storage tank 5 Pump 6 Flow rate adjustment valve 7 Temperature adjustment device 8 Mist trap 9 Drain tank 10 For mist suction Fan 11a Contact start part 11b Contact end part

Claims (8)

In a continuous processing line for attaching a treatment liquid to a steel plate, a cleaning method for a roll that comes into contact with the steel plate after the treatment liquid has adhered,
Covering at least a part of the surface of the roll with a cleaning cover from the contact end portion where the steel plate ends contact with the roll to the contact start portion where the steel plate starts contact with the roll,
A cleaning method for a roll that sucks the drainage liquid in the cleaning cover while discharging the cleaning liquid to the surface of the roll inside the cleaning cover.   The roll cleaning method according to claim 1, wherein the amount of the treatment liquid attached to the surface of the roll in the subsequent stage of the cleaning cover is adjusted by controlling a suction pressure of the drainage liquid in the cleaning cover.   The method for cleaning a roll according to claim 1 or 2, wherein a treatment liquid or water is applied to the surface of the roll at a stage subsequent to the cleaning cover and before the contact start portion.   The amount of the processing liquid desorbed from the surface of the roll by washing is calculated by analyzing the waste liquid, and an amount of the processing liquid or water corresponding to the amount of the desorbed processing liquid is applied. How to clean the rolls. In a continuous processing line for attaching a processing liquid to a steel plate, a roll cleaning device for cleaning a roll that comes into contact with the steel plate after the processing liquid has adhered,
A cleaning cover that is provided between a contact end portion where the steel plate ends contact with the roll and a contact start portion where the steel plate starts contact with the roll, and covers at least a part of the surface of the roll;
A cleaning liquid discharging means provided inside the cleaning cover and discharging a cleaning liquid toward the surface of the roll;
A roll cleaning device provided inside the cleaning cover and having suction means for sucking the drainage.   The roll cleaning apparatus according to claim 5, wherein the suction unit is capable of controlling the suction pressure so as to adjust the amount of the treatment liquid adhered to the surface of the roll in the subsequent stage of the cleaning cover.   The roll cleaning apparatus according to claim 5, further comprising an application unit that applies a treatment liquid or water to a surface of the roll at a stage subsequent to the cleaning cover and before the contact start portion.   The roll cleaning apparatus according to claim 7, wherein the coating unit applies a treatment liquid or water in an amount corresponding to the amount of the treatment liquid detached from the surface of the roll by cleaning.

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