METHOD FOR CLEANING A ROLLING MILL ROLL AND CORRESPONDING DEVICE
The present invention relates to cleaning a rolling mill roll, in particular a skin-pass mill, implemented at the outlet of continuous galvanization lines, by a high pressure jet.
A skin-pass mill comprises a pair of support rolls on which rest a pair of work rolls between which a galvanized strip is laminated.
During their passage between the work rolls, some zinc particles which derive from the surface of the galvanized strips may adhere to the work rolls which may also transfer them to the support rolls. .
Consequently, these particles may imprint on the coating of the strip each time the roll rotates and may sufficiently alter the quality of the surface such that the product may become unsalable or require downgrading.
Furthermore, on certain skin-pass mills, it is necessary to ensure lubrication of the gap between the work rolls with a water and lubricant emulsion in order to reduce the effort for the tension and lengthening given. Generally the result is a greasy deposit on the work rolls in areas which are not in contact with -the strip.
And when changing the product being laminated to a product with a wider strip, this greasy deposit may prove harmful on the two edges of the new strip and lead to a visual appearance fault of the latter.

To compensate for these disadvantages, it is known in document JP 9262607 in which mechanized means for cleaning the rolls by pressurized spraying of detergent fluid are implemented. However, these devices require low pressure spray nozzles with a large jet which, if they prove to be efficient enough to degrease the coatings of lubrication product due to the detergent effect of the sprayed liquid are, however, not effective enough to remove the adhesive particles, in particular the zinc particles.
Other types of high energy spray nozzles with a narrow jet are known. Such nozzles require, on the one hand, precise adjustment of the distance between the nozzle and the roll to be cleaned and therefore, adaptation to the diameters of. the various work rolls used, and on the other hand, in order to have a coverage of the impact of the jets along the roll, it is advisable either to implement a significant number of spray nozzles, which is unreasonable in terms of cost and mechanical complexity, or to implement a nozzle mounted on a mobile lance.
Patent EP 0 995 504 describes a cleaning method comprising mobile lances, capable of being displaced along the roll, in other words, in parallel to its axis of rotation. This arrangement demands perfect synchronization of the rate of displacement of the lance in relation to the rotational speed of the roll according to the impact width of the jet.
However, considering the relatively small impact size of the jet, it is necessary to have a relatively slow rate of displacement of the cleaning lance or lances in order to guarantee good coverage of the impact of the jet.

Such a solution is therefore time-consuming and consuming in terms of cleaning products.
The present invention proposes a solution which enables the use of spray devices to be optimized in order to reduce the consumption of fluids - therefore discharge - and to avoid wasting time.
With this objective in mind, according to one of its first objectives, the invention concerns a method for cleaning a rolling mill roll, comprising a cleaning step during which a nozzle functions at a cleaning speed whilst being displaced parallel to the axis of the roll according to a cleaning speed. According to the invention, the method is mainly characterized in that it furthermore comprises a determining step during which, on the roll, at least one working area delimited by a start of work position and an end of work position is determined, and the cleaning step is limited to the working area.
According to another of its objectives, the invention also concerns a device for cleaning at least one rolling mill roll, which is capable of implementing the method according to the invention. The device comprises:
a cleaning nozzle configured to apply a pressurized cleaning product to a roll to be cleaned, and
means to displace the nozzle. According to the invention, the device is essentially characterized in that it furthermore comprises:
means to determine at least one working area delimited by a start of work position and an end of work position, and
means to limit the cleaning step to the working area.

Due to the invention, it is unnecessary to move the lance or lances along the generator mechanism of the roll to be cleaned. Cleaning may be selective, by choosing one or more working areas. Other characteristics and advantages of the present invention will become more clear when reading the following description, given as an illustrative and non-exhaustive example, and made with reference to the figures in the appendix in which:
figure 1 illustrates a cross-section of an embodiment of the device according to the invention,
figure 2a illustrates an embodiment of an axial adjusting device according to the invention,
figure 2b illustrates a section according to axis XX of figure 2A,
figure 3A illustrates the working and rest positions for a lance and two working areas,
figure 3B illustrates the working and rest positions for two lances and two working areas,
figure 3C illustrates the working and rest positions for one lance and one working area, and
figure 4 illustrates another embodiment of the device according to the invention.
With reference to figure 1, a metal strip 1 to be laminated passes between the work rolls 2a, 2b of a skin-pass mill. These work rolls are themselves supported by support rolls 3A, 3B. The device according to the invention comprises a cleaning nozzle 61 mounted on a lance and configured to apply a pressurized cleaning product to the roll being cleaned.
At least one nozzle is provided for in order to clean at least one roll, in such a way that one nozzle can clean several rolls

and several nozzles can clean one single roll.
Each lance is equipped with at least one nozzle, in the case in point, a single respective nozzle.
Thus, in an embodiment (figure 1, figure 3A), at least one lance 6a ensures the cleaning of the upper work roll 2a, and at least one other lance 6b ensures the cleaning of the lower work roll 2b. For certain applications, at least one lance 7a can be provided for in order to ensure the cleaning of the upper support roll 3A, and similarly, at least one other lance 7b can be provided for in order to ensure the cleaning of the lower support roll 3B.
In another embodiment (figure 3B), at least one roll (or each roll) may be cleaned by a plurality of lances, in the case in point, two.
The invention aims to clean, principally, at least one of the work rolls.
The lances 6a, 6b intended for cleaning at least one of the work rolls comprise a spray nozzle 61, and a body 62 supplied with cleaning product, in the case in point, a pressurized fluid by a hose 63. The body 62 is supported by an axial adjusting device 64 itself carried by means to displace the nozzle, in the case in point, a translation device 65.
An example of an axial adjusting device 64 is illustrated in figures 2A and 2B in which the translation and rotational movements are schematized by wide arrows.

The axial adjusting device 64 comprises a support 641 mounted and able to pivot on the slide 652 of the translation device 65 in order to enable the angle of inclination a of the lance 6a, 6b to be adjusted in relation to the roll 2a, 2b.
Pivoting of the support 641 in relation to the slide 652 may be motorized, for example with a servomotor. It is therefore possible in this embodiment to use only two pivoting lances, each respectively ensuring the cleaning of a work roll 2 then of a support roll 3. A first control component 643 ensures adaptation to the diameter of the rolls.
Another slide 642 is mounted to the support 641, the former capable of being_ displaced in parallel to the axis of the lance 6a, 6b under the action of the first control component 643 which is able to adjust the relative position of the nozzle 61 to the required distance from the surface 21 of the work roll 2a, 2b. Displacement of the slide 652 can be achieved with a belt system as illustrated in figure 2A, or a chain system, or indeed a ball screw. The drive is favorably ensured by a servomotor. The slide 652 is a guided carriage on a rail 651 by rollers.
The translation device 65 comprises the rail 651 fixed to the frame of the skin-pass mill and the slide 652 which is capable of being displaced parallel to the longitudinal axis of the roll 2a, 2b under the action of a second control component 653 which is able to ensure the displacement of the axial adjusting device 64 carrying the lance 6a, 6b parallel to the axis of the work roll 2a, 2b.
In an embodiment which is not represented, the first control

component 643 and the second control component 653 are the same. Preferably, the nozzle is set into motion, possibly a forwards and backwards motion, parallel to the axis of rotation of the roll being cleaned, in accordance with a first speed.
In a manner known per se, the first speed is subject to at least one of the following parameters: diameter of the roll being cleaned, rotational speed of said roll, and the impact width of the jet emitted by the nozzle on said roll. This control of speed in the cleaning phase is, for example, implemented by the control component 653.
According to the known diameter of the work roll and of the angle a (figure 1) of the lance 6a, 6b in relation to the roll 2a, 2b, the control component 643 of the axial adjusting device 64 positions the nozzle 61 at the required distance from the surface 21 of the work roll 2a, 2b.
The control component 643 enabling adjustment of the nozzle position in relation to the surface of the roll can be actuated by a hydraulic or pneumatic cylinder, may also be equipped with a position sensor or, as an alternative, by a servomotor driving a wheel and ball screw mechanism, a rack and pinion mechanism or even a belt mechanism.
According to the rotational speed of the work roll 2a, 2b, the control component 653 of the translation device 65 displaces the nozzle 61 at the required speed and controlled along the surface 21 of the work roll 2a, 2b in order to guarantee, as the roll rotates, optimal coverage of the impact of the cleaning jet, in such a way that the entire surface of the roll to be cleaned is

covered.
Thus a cleaning speed, or a working speed, can be determined in which the nozzle is displaced at a given cleaning speed, and releases cleaning fluid at a given cleaning pressure and a given cleaning flow.
Furthermore, the invention comprises means to determine at least one working area delimited by a start of work position and an end of work position on the roll to be cleaned, and means to limit the cleaning stage to said working area.
According to the invention, a roll may comprise a plurality of working areas.
The means to determine at least one working area are optical means configured to obtain at least one image of the rolls and/or the strip.
Each working area may comprise a coverage area R.
In an embodiment, figure 1, the optical means comprise at least
one camera 8a, 8b, 8c, 8d of which the image is sent to a control
screen present in a control booth of the rolling mill.
An operator may therefore assess the images sent and determine
the start and end of work positions for each working area.
In another embodiment, determination of the working areas is
implemented automatically by a surface fault detection system
10a, 10b (figure 4).
An illuminator device 101 lights up the coated strip 1 at the output of the skin-pass mill. A high definition camera CCD 102 captures the image of the unwinding strip. Such devices are

known, for example in the application EP 0 974 833.
The image acquired by the camera CCD 102 is sent to a filter unit 103 whose function is to eliminate any distortion due to vignetting and to non-uniformity of illumination.
The filtered images are then processed in a gray-level or contour detection type image processing unit 104 which enables more contrasting areas considered as "suspect areas" to be revealed, in other words, probably containing particles to be cleaned. Favorably according to the invention, it is not compulsory to use sophisticated morphological analysis models with a view to distinguish different types of faults.
In another embodiment, which may be alternative or combinable, and not represented, the cleanliness of the roll is determined by a stage for measuring the surface profile of said roll. To this effect, the device according to the invention comprises means to determine at least one area to be cleaned, said means to determine at least one cleaning area comprising means for measuring the surface profile of said roll by bundle or laser beam triangulation, adhesion of the foreign bodies (zinc particles, lubrication products, etc.) being measured as variations in the profile measured.
It is cited as a commercial reference the product scanCONTROL 2800 manufactured by MICRO EPSILON for measuring the surface profile.
A laser line is projected onto the surface of the roll being cleaned. A return optic reproduces the light reflected from this

laser line onto the camera matrix, in the case in point CMOS. From this camera image, a controller calculates not only distance information (axis z), but also the real position along the laser line (axis x), and publishes the two results in a system of bi-dimensional co-ordinates.
A 3D representation is obtained by displacement of the laser sensor along the roll.
A laser bundle or beam triangulation sensor may be mounted on the lance support 62. It sweeps the surface of the roll being rotated by high speed displacement of the slide 652 on the runners 651 and delivers positional information of the clogged areas to be cleaned with reference to the displacement encoder of the slide 652.
The size of the beam is, for example, from 1 to 150 mm, and preferably between 10 and 100 mm.
Favorably, the device according to the invention comprises, furthermore, air blowing means, in the case in point, a compressed air blowing nozzle, cooperating with said means to determine at least one area to be cleaned, in order to dry the surface of the roll being analysed.
Favorably, a protective cover is used to protect the triangulation window during the cleaning stages.
Visual or automatic detection of faults enables the limits of a working area 20, 21 or a cleaning area 10, 11, 12 to be defined. A working area 20, 21, 22 comprises a start of work position, in

the case in point
B and D in figure 3A,
B and B1 in figure 3B, and
I in figure 3C, and an end of work position, in the case in point and respectively
C and E in figure 3A,
C and C in figure 3B, and
J in figure 3C.
A working area comprises an area to be cleaned, possibly increased by one or two coverage areas R.
An area to be cleaned 10, 11 (shaded area, figures 3A, 3B, 3C) is delimited by a start position of the area being cleaned, in the case in point
B and G in figure 3A,
B and B1 in figure 3B, and
K in figure 3C, and an end position of the area being cleaned, in the case in point and respectively
F and E in figure 3A,
F and F1 in figure 3B, and
L in figure 3C. For example:
Position A represents a rest position for a first lance 6 (figures 3A, 3B, 3C), and position A1 represents a rest position for a second lance 6' (figure 3B).
Figure 3A illustrates an embodiment in which the cleaning stage is implemented by a single lance 6. A roll 2 comprises a first

area to be cleaned 10 and a second area to be cleaned 11. In this example, the areas being cleaned correspond to the ends of the roll 2 which are not in contact with the laminated strip 1, and it is possible to define, respectively to the areas to be cleaned, a first working area 20 and a second working area 21 of which each comprises a coverage area R,.in the case in point, with the same dimensions.
Figure 3B illustrates a variation of figure 3A in which the same areas are to be cleaned and the same working areas are defined, but cleaning is implemented respectively by a first lance 6 and a second lance 6'. Positions A', B1, C are symmetrical to positions A, B, C in figure 3B for the second lance 6'. In an embodiment which is not represented, rest positions A and A' may be located on the same side of the roll 2.
Figure 3C illustrates an embodiment in which the cleaning stage is implemented by a single lance 6. A roll 2 comprises an area to be cleaned 12 corresponding to the surface of the laminated strip 1. A working area 22 is defined comprising, in the point in case, a first and second coverage area R, located at each end of the width of the laminated strip 1.
To illustrate an implementation, typically, a cleaning nozzle is first positioned in a rest position A.
In a transport stage, the nozzle is displaced parallel to the axis of the roll from an end of work position, and/or to a start of work position.
In the case in point:
to a start of work position, in other words, from the rest

position A to position B (figures 3A, 3B),
from an end of work position of another working area, in other words, from position C to position D, figure 3A, - and/or to the rest position, in other words, from an end of work position of a working area, for example from position E to position A (figure 3A), or from position C to position A (figure 3B), and from position C to position A1 (figure 3B), and from position J (figure 3C) to position A.
Once the working area has been determined, the cleaning stage can, due to the invention, be limited to this working area. The limitation is implemented due to a transport stage during which the nozzle operates at a different speed to the cleaning speed, and i.s displaced parallel to the axis of the roll from an end of work position, and/or to a start of work position. In this transport stage, the nozzle operates at a different speed from the cleaning speed.
The operating speed is characterized by at least one of the following parameters: displacement speed, flow supplied by the nozzle, and cleaning fluid pressure at the nozzle outlet. In an embodiment, during the transport stage, displacement of the nozzle out of said working area is performed at a second speed, known as the transport speed, which is different from the first speed, known as the cleaning speed, which is greater in the case in point.
Favorably, the second speed is not subject to the rotational speed of the roll, and it is maximally preferable as a function of the means to displace the nozzle.

In an embodiment, during the transport stage, the flow, in other words, the amount of cleaning product delivered by the nozzle per unit of time, is different from the cleaning flow, which is less in the case in point, delivered during the cleaning stage. In an embodiment, during the transportation stage of the nozzle, the cleaning product is applied to the roll to be cleaned under a second pressure which differs from the first (cleaning pressure), in the case in point less or indeed at zero pressure (supply of cleaning product cut off).
For example, as a function of the known width of the strip 1, the control component 653 of the axial adjusting device 65 positions the nozzle 61 at maximum speed along the surface 21 of the work roll 2a, 2b in order to start and stop the cleaning at the exact point necessary.
In the example of figure 3A, the lance 6 moves at maximum speed from its rest position A to the start of cleaning position B of a dry emulsion deposit 9a corresponding to an edge of the roll table then ensures cleaning at a monitored cleaning speed from B to C, then positions itself at maximum speed at the start D of the second deposit of dried emulsion 9b then ensures cleaning at a monitored cleaning speed from D to E and finally returns at maximum speed to the rest position A. The coverage R enables the working area to be adjusted.
In the example of figure 3B, two lances 6, 6' are positioned which both move at maximum speed from their rest position A, A' to their respective start of work positions B, B' of dried emulsion deposits 9a, 9b then ensures cleaning at a monitored speed from B and B" to C and C respectively and return to their

respective rest position A, A' at maximum speed.
In the example of figure 3C, the lance 6 moves at maximum speed from its rest position A to the start of work position I then ensures cleaning at a monitored cleaning speed from I to J in order to clean the zinc particles adhering to the strip 1, then returns at maximum speed to its rest position A. In this example, the working area 22 comprises a first area of coverage, upstream, extending from the start of work position I to the start of position area of the area to be cleaned K, and a second area of coverage, downstream, extending from the end of position area of the area to be cleaned L to the end of work position J. A control unit 105 determines the start and end of areas to be .cleaned by possibly adding a coverage R within a work area at the edges of the suspect areas as soon as they appear and delivers displacement commands to the actuators 653 (cleaning speed in a work area and different speed outside of the work area). As an alternative, the control unit 105, as soon as the suspect areas appear, delivers the displacement commands to the actuators 653 (cleaning speed in a work area and different speed outside the work area) ensuring, depending on the case, cleaning of the complete width of a roll or of the single width corresponding to the contacting width with the strip increased by one or more coverages R or indeed extreme parts of the rolls alone which are not in contact with the strip increased with coverages R (figures 3A, 3B, 3C).
Triggering of the cleaning operation can be achieved automatically or manually.
The invention is not restricted to the embodiments previously

described. Other variations are possible, for example: In an embodiment, figure 1, of the lances 7a, 7b can be used in order to also clean the support rolls. In this case, they can be fixed to the same slide 652 as the lances 6a, 6b. Although the support rolls 3A, 3B are changed less often than the work rolls 2a, 2b and adjustment of the distance between the nozzle 71 and the roll surface 31 does not necessarily require it, the lances 7a, 7b can also have their own axial adjusting device.
In an embodiment (figure 1), for certain applications, the device furthermore comprises lubricating emulsion spray bars 4a, 4b to ensure lubrication of the air gap 5.
In an embodiment which is not shown, a CCD camera may be installed and integral to each lance's casing 62. Each camera obtains images of the surface of the rolls (work and support rolls if the support 641 is mounted such that it pivots in a motorized manner on the slide 652, as previously seen) during the lamination phases where the cleaning steps are not implemented. These images are processed in a standard manner (Automatic Surface Inspection System) and the variations in contrast identified, after processing, like dirt command the activation of the cleaning lances. A diaphragm advantageously protects the lens of the cameras during cleaning.

CLAIMS
1. A method for cleaning a rolling mill roll (2, 3), comprising a
cleaning stage during which a nozzle operates at a cleaning speed
whilst being displaced parallel to the axis of the roll according
to a cleaning speed, characterized in that it furthermore
comprises a determining stage during which at least one working
area (20, 21, 22) delimited by a start of work position (B, B1,
D, I) and an end of work position (C, C, E, J) is determined on the roll (2, 3), and such that the cleaning step is limited to the working area (20, 21, 22).
2. The cleaning method as claimed in claim 1, characterized in that it comprises a transport stage during which the nozzle, operating at a different speed to the cleaning speed, is displaced in parallel to the axis of the roll (2, 3) from an end of work position (C, C, E, J), and/or to a start of work position (B, B1, D, I).
3. The cleaning method as claimed in claim 2, characterized in that, during the transport stage, the nozzle is displaced from an end of work position (C) of a first working area (20) to a start of work position (D) of a second working area (21).
4. The cleaning method as claimed in one of claims 2 to 3, characterized in that, during the transport stage, the flow of cleaning product applied by the nozzle is less than the cleaning flow.
5. The cleaning method as claimed in one of claims 2 to 4,

characterized in that, during the transport stage, the pressure of the cleaning product applied by the nozzle is less than the cleaning pressure.
6. The cleaning method as claimed in one of claims 2 to 5, characterized in that during the transport stage, the transport speed is greater than the cleaning speed.
7. The cleaning method as claimed in one of claims 1 to 6, characterized in that the working area (20, 21, 22) comprises one area (10, 11, 12) to be cleaned delimited by a start position of the area to be cleaned (B, B', G, K) and an end position of the area to be cleaned (F, E, F1, L).
8. The cleaning method as claimed in claim 7, characterized in that the working area (21, 22) comprises furthermore a first coverage area (R) extending from the start of work position (D, I) to the start position of the area to be cleaned (G, K).
9. The cleaning method as claimed in claim 7 or 8, characterized in that the working area (20, 21, 22) comprises furthermore a second coverage area (R) extending from the end of area position (F, F1, L) of the area to be cleaned (10, 11, 12) to the end of work position (C, C, J) .
10. The cleaning method as claimed in one of claims 1 to 9,
characterized in that the working area (20, 21, 22) is
predetermined as a function of the width of the laminated strip
(1) •
11. The cleaning method as claimed in claim 10 which is dependent

on one of claims 7 to 9, characterized in that the area to be cleaned (12) is delimited by two edges (K, L) of the laminated strip (1) .
12. The cleaning method as claimed in claim 10 which is dependent on one of claims 7 to 9, characterized in that the area to be cleaned (10, 11) is delimited on the one hand, by one edge of the roll (B, B', E), and, on the other hand, by the edge (F, F', G) of the laminated strip (1) which is closest to the latter edge of the roll.
13. The cleaning method as claimed in one of claims 1 to 12, characterized in that the working area is determined by a visual inspection of the cleanliness of the roll and/or the cleanliness of the laminated strip.
14. The cleaning method as claimed in claim 13, in which the cleanliness of the roll is determined by a stage for measuring the profile of the surface of said roll.
15. A cleaning device of at least one rolling mill roll, capable of implementing the method according to any of the previous claims, the device comprising:
a cleaning nozzle (61) configured to apply a pressurized cleaning product to the roll (3,4) to be cleaned, and
means (641, 642, 652) to displace the nozzle, characterized in that it comprises furthermore:
means to determine at least one working area delimited by a start of work position and an end of work position, and
means to limit the cleaning stage to the working area.

16. The device as claimed in claim 15, in which the means to displace the nozzle are configured to displace the nozzle according to a first speed in the working area, and according to a second speed which differs from the first speed outside of said working area.
17. The device as claimed in any one of claims 15 or 16, furthermore "comprising a second cleaning nozzle (71) configured to clean said roll to be cleaned or another" rolling mill roll.
18. The device as claimed in any one of claims 15 to 17, in which the means to determine at least one working area on the roll to be cleaned comprise optical means (102) to obtain an image of the surface of the laminated product, and processing means (103, 104) for the image obtained.
19. The device as claimed in any one of claims 15 to 18, furthermore comprising means to determine at least one area to be cleaned, said means to determine at least one area to be cleaned comprising means for measuring the surface profile of said roll by bundle or laser beam triangulation
20. The device as claimed in claim 19, furthermore comprising air blowing means cooperating with said means to determine at least one area to be cleaned.