ROLLER CLEANING METHOD AND ROLLER CLEANING MACHINE

Abstract

A method for cleaning rollers used for metal strip processing. According to said method, the roller surface is cleaned by an aqueous alkali metal hydroxide or alkaline earth metal hydroxide washing liquid or an acidic washing liquid, the washing liquid is removed and the roller surface is dried. A machine for cleaning rollers includes a washing frame designed for positioning a roller to be cleaned, and at least one means for applying at least one washing solution to the roller surface of the roller to be cleaned.

Claims

1. A method for cleaning rolls used in metal strip processing whereby the roll surface is cleaned with an aqueous alkali metal or alkaline earth metal hydroxide washing liquid or an acid washing liquid, comprising that the roll to be cleaned is a work roll with impurities resulting from aluminum strip processing, whereby the roll is cleaned in a washing mount, the surface of the roll to be cleaned is cleaned in succession with a first and at least one second alkaline or acidic washing liquid, whereby the first alkaline washing liquid has a higher concentration of hydroxide ions than the at least second alkaline washing liquid, or the surface of the roll to be cleaned is cleaned in succession with a first and at least one second acidic washing liquid, whereby the first acidic washing liquid has a higher concentration of mineral acid or carboxylic acid than the at least second acidic washing liquid, and whereby the roll surface is rinsed with water upon completion of cleaning with the alkaline or acidic washing liquids.

2. The method according to claim 1, wherein the concentration of alkali metal hydroxide in the first washing liquid is 2 to 4% by weight, relative to the weight of the washing liquid.

3. The method according to claim 1, wherein the concentration of alkali metal hydroxide in the second washing liquid is 0.3 to 1% by weight, relative to the weight of the washing liquid.

4. The method according to claim 1, wherein the concentration of mineral or carboxylic acid in the first acidic washing liquid is 2 to 4% by weight, relative to the weight of the acidic washing liquid.

5. The method according to claim 1, wherein the concentration of mineral or carboxylic acid in the second acidic washing liquid is 0.3 to 1% by weight, relative to the weight of the acidic washing liquid.

6. The method according to claim 1, wherein the first and/or the second washing liquid and the first and/or the second acidic washing liquid contain a degreasing agent.

7. The method according to claim 1, wherein the following steps are carried out in succession on a roll to be cleaned: cleaning the roll with the first washing solution containing alkali metal hydroxide or alkaline earth metal hydroxide and a degreasing agent, cleaning the roll with the second washing liquid containing alkali metal hydroxide or alkaline earth metal hydroxide, whereby the concentration of alkali metal hydroxide or alkaline earth metal hydroxide in the first washing liquid is higher than that of the second washing liquid, rinsing the roll with demineralized water as a third washing liquid, and cleaning the roll with a fourth washing liquid that contains an alkanol or an alkanol/water mixture and subsequently drying the roll.

8. The method according to claim 7, wherein the concentration of alkali metal hydroxide or alkaline earth metal hydroxide in the first washing liquid is adjusted to 2 to 4% by weight and the concentration of alkali metal hydroxide or alkaline earth metal hydroxide in the second washing liquid is adjusted to 0.3 to 1% by weight, in each case relative to the weight of the washing liquid.

9. The method according to claim 7, wherein the roll to be cleaned is not allowed to run dry during the cleaning and rinsing steps.

10. The method according to claim 9, wherein the surface of the cleaned roll is dried.

11. The method according to claim 1, wherein the rolls used in aluminum sheet processing are cleaned in a device that comprises: a washing mount designed for positioning a roll to be cleaned, and at least one aid for applying at least one washing liquid onto the surface of the roll to be cleaned.

12. The method according to claim 11, wherein the aid for applying at least one washing liquid possesses at least one nozzle and/or at least one scoop roller.

13. The method according to claim 12, wherein the aid for applying at least one washing liquid includes at least one scoop roller, whereby the roll and the scoop roller are arranged such that they roll over each other and whereby a means is provided to slow down the rotation speed of the roll and/or the scoop roller.

14. The method according to claim 11, wherein in that several tanks are provided for washing liquids, whereby the tanks are connected by means of valve units with the aid for applying at least one washing liquid.

15. The method according to claim 11, wherein the device is equipped with at least one aid for removing a washing liquid from the surface of the roll.

16. The method according to claim 11, wherein the device is equipped with at least one aid for drying the surface of the cleaned roll.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0053] FIG. 1 shows a schematic representation of an example of a devicein side view with the roll to be cleanedfor performing the method according to the invention.

[0054] FIG. 2 shows a schematic representation of an example of a device in front view with roll.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0055] An example of a roll washing system for implementing the method according to the invention comprises a washing mount (10) on which the roll (1) is placed for cleaning. The roll (1) is mounted on the washing mount (10) such that it can rotate about its own axis. A drive (9) is used to rotate the roll (1). A basin or trough for collecting liquid (8) is located under the roll (1). This basin (8) can be filled with the respective washing solution or with water during the roll cleaning process and can collect washing solutions while the roll (1) is being cleaned. A rotatable scoop roller (14) is mounted parallel to the longitudinal axis of the roll (1) to be cleaned. A spring-loaded mechanism can be used to allow the scoop roller (14) to come into contact with the roll (1) to be cleaned. The scoop roller (14) can be used to apply a washing solution from the basin (8) to the roll (1). It can also be used to brush the surface of the roll (1). An electric motor is used to rotate the scoop roller (14) and/or the roller (1) in both directions of rotation, whereby the speed of rotation can be set to 20 m/min or to another speed. An aid for braking the speed of rotation of the scoop roller (14) is to be provided. The respective washing solutions can also be applied to the roll (1) to be cleaned via nozzles (6). The nozzles can spray the washing solution directly onto the roll surface and/or onto the scoop roller (14). The scrapers/squeegees (12) serve to reduce the quantity of liquid (washing liquid/water) on the surface of the roll, in particular at the edges of the roll (1) to be cleaned, after a wash cycle.

[0056] In an example of an automated cleaning process according to the invention, the roll (1) to be cleaned is positioned on the washing mount (10) in the device or roll washing system. To commence cleaning, valve MV1 is opened and pump P1 is switched on. Electric motor M1 makes the roll to be cleaned rotate about its own axis. A chelating degreasing agent in a strong alkaline washing solution (solution 1; 2 to 4% by weight alkali hydroxide) stored in a storage tank (4A) is applied to the roll and the roll is initially cleaned with this solution. The scoop roller (7) brushes roll 1 and supports the cleaning process. Solution 1 is drained and collected in basin 8. The used solution 1 in the basin (8) is returned to storage tank 4A via open valve 4.1. After 30 minutes of cleaning the roll (1) with solution 1, valve 4.2 is closed. If there is no more washing solution in the basin, valve 4.1 is also closed. Valve 4.4 is opened. An alkaline washing solution 2 with an alkali hydroxide concentration of 0.5 to 1.0% by weight (solution 2), regulated by valve 4.4, flows from tank 4B to the nozzles (6) from where it is applied to the roll (1) for further cleaning. Washing liquid 2 also contains a chelating degreasing agent. After 30 minutes, the supply of solution 2 to the nozzles (6) is interrupted by valve 4.4. After the used solution 2 has drained from the basin (8) into storage tank 4B, valve 4.3 is also closed. Fully demineralized water is now supplied via valve MV3 to the nozzles (6) and subsequently to the roll (1) for further cleaning. This cleaning step with demineralized water (demineralized waterwashing liquid 3) can also take 30 minutes and is supported by the scoop roller (14). After the used demineralized water is drained out of the basin (8), the roll (1) is washed with isopropanol (solution 4) for purposes of cleaning as well as for removing washing water. This step can also be performed for 30 minutes. Isopropanol is drained from the basin (8) and the roll (1) is then dried further. An air blower can be used for drying the roll.

[0057] In another example of an automated cleaning method according to the invention, the roll (1) to be cleaned is positioned on the washing mount (10) of the roll washing system in a customized device. Via open valve MV1 and by operating the pump (7.1), the alkaline degreasing washing liquid is now applied via flush nozzles from the storage tank (4A), by opening valves 4.2. and 4.1., onto the scoop roller (14) in the top area. The roll to be cleaned is now made to rotate at an appropriate speed (e.g. 10 rpm) via the drive and coupling unit (9, 10) before the scoop roller is moved up to the roll. A pneumatic or hydraulic system can be used to determine the contact pressure of the scoop roller, which is now either rotated freely or slowed down or driven.

[0058] The type of rotation selected for the scoop roller depends on various factors such as the coating of the scoop roller, the material of the work roll and the type and intensity of the impurities. The washing solution is now applied to the roll to be cleaned in a uniform film layer. Excess liquid is drained into the trough/basin located below, whereby scrapers/squeegees (12) ensure that no washing solution reaches the edge or even the journal of the roll.

[0059] The liquid (8) collected in the trough/basin (3) can either be recirculated and allowed to flow freely to the tank directly (or a pump) or, controlled by a level measurement, it can be accumulated so that the washing roller can also be used as a scoop roller (FIG. 1).

[0060] After a preset washing time, the first washing solution is now run over by the second washing liquid from tank 4B by first opening valves 4.4. and 4.3. and, shortly afterwards, closing valves 4.2. and 4.1.

[0061] This moving from one into another ensures that the roll to be washed does not run dry. Dry running must be prevented in so far as, for example, some metals can form oxide compounds which very quickly become insoluble and reach a degree of hardness that exceeds that of the roller surface and could cause pressure marks later in the process.

[0062] After another preset washing time, washing solution 2 is drained off and rinsing with demineralized water fed via valve MV3 is now carried out. In this context too, an early switchover prevents the roll from running dry prematurely.

[0063] Finally, rinsing is carried out preferably with an aqueous solution with an isopropanol content of 10 to 20% that is fed from tank 4C, before the scoop roller (14) is retracted and the roll (1) continues to rotate and is dried thoroughly either by the ambient air or with the help of a blower. Once dry, rotation is stopped and the roll, which is ready for use, is discharged from the washing system.

[0064] All references, including publications, patent applications, and patents cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.

[0065] The use of the terms a and an and the and similar referents in the context of describing the invention (especially in the context of the following claims) is to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms comprising, having, including, and containing are to be construed as open-ended terms (i.e., meaning including, but not limited to,) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., such as) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

[0066] Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.