The invention relates to a cooling device for a hot-rolling mill for a metal strip, the hot-rolling mill having at least one pair of work rolls each having a work roll sur face, the cooling device comprising a shovel-shaped body comprising a plurality of openings arranged to project a cooling fluid on a work roll, and a scraper arranged to prevent the cooling fluid from spilling on the metal strip, when in use, and a pressure means for pressing the scraper against said work roll surface. It also relates to a hot- rolling mill comprising such a cooling device.

Such a cooling device for a hot-rolling mill is known from patent EP 2164 651 B1. This known cooling device is equipped with cooling jets and scraper jets. The cooling jets are arranged perpendicularly to the surface of the work roll. The scraper jets are oriented in the desired flow direction following a re-entrant angle towards the perpendicular to the surface of the work roll. The cooling fluid used could be water or a water and oil emulsion, with or without surfactants.

Another cooling device for a hot-rolling mill is known from EP 21 14 584 B1. This cooling device uses transverse plates, acting as scrapers, arranged longitudinally relative to the work roll and are located at a distance from the roll such that the plates ensure that the cooling liquid flow is controlled and forms a highly turbulent water cushion.

Further a cooling device is known from DE 10 2009 053073. This cooling device has at least two segments connected to each other in a moveable manner.

In practice it has turned out that the scrapers must be replaced often because of excessive and / or uneven wear. This will lead to spilling of the cooling fluid on the metal strip and disturbs the normal processing as it results in cooling the metal strip in a forceful and uncontrolled way, leading to defects in the metal strip. Further it intro duces down-time, leading to production losses.

The current invention relates to a cooling device for a hot-rolling mill with im proved service life, having less wear, leading to less down-time. It also relates to a more predictable wear.

In a first aspect of the invention the shovel-shaped body is further comprising one or more spacers arranged to contact the work roll surface. This has the ad vantage that also a predefined distance between the shovel-shaped body and the work roll surface is created, leading to a predefined cushion of cooling fluid and a stable position of the shovel-shaped body. Because the one or more spacers are ar ranged to contact the work roll surface with a predefined force, there is also an even, and controlled, wear of the one or more spacers. As the force can be set in advance, the wear of the one or more spacers could be set such that the force of the contact is set to a minimum value needed for a stable process and a stable cooling fluid cush ion size resulting in less wear.

It may be preferable that the one or more spacers are arranged to contact a part of the work roll surface in the vicinity of a back-up roll, when in use. A hot-rolling mill usually is equipped with work rolls and back-up rolls contacting the work rolls. This configuration is well known to a person skilled in the art and therefore requires no further elucidation. The one or more spacers are positioned such that room is pro vided for the cooling fluid to escape from the area between the work roll surface and the shovel-shaped body, in the direction of the back-up roll. As the scraper is general ly located at one end of the curved portion of the shovel-shaped body, in the vicinity of the metal strip, when in use, the one or more spacers are preferably located at the other, or opposite end of said curved portion, in the vicinity of the back-up roll, when in use. In that way a more balanced force on the work roll surface could be generat ed, since the at least two points of contact so created give the option of balancing out the forces over these points of contact. It may therefore be preferable that the scrap er is arranged to contact a part of the work roll surface in the vicinity of the metal strip, when in use.

It is preferable that the one or more spacers are positioned at the extremities of the shovel-shaped body. This has the benefit of having even more stability since po sitioning of the one or more spacers at the extremities of the shovel-shaped body allows a better alignment of the one or more spacers on the work roll surface and therefore also the scraper is aligned better on the work roll surface. As explained ear lier, uneven wear is something that needs to be prevented. As the scraper is ar ranged over the entire length at one end of the curve shaped portion of the shovel shaped body, it is preferable that the wear is also even, as uneven wear makes the cooling fluid spill to the metal strip. The configuration with the pressure means and the additional pressure makes it possible to control the force the scraper exercises over the entire length of the scraper leading to an even and minimal wear of the scraper.

It is preferable that the scraper is a mechanical scraper made of a rigid material. Mechanical scrapers have the benefit of being relatively cheap and still provide an elegant way of preventing the cooling fluid from spilling on the metal strip. Other than that, they are relatively easy to replace, giving less disturbance in the production envi ronment. Preferred is a scraper made of a rigid material to prevent wear, but also other materials could be used depending on the specific requirements. Also other types of scrapers could be used.

It is preferred that the cooling device further comprises at least one additional pressure means arranged to cooperate with the pressure means to press both the scraper and the one or more spacers against the work roll surface with a predefined force.

The at least one additional pressure means give the shovel-shaped body an extra controlled movement option since the at least one additional pressure means cooperate with the pressure means. The pressure means are arranged to move the shovel-shaped body in a to-and-fro movement with respect to the work roll surface. It is also arranged to tilt the shovel-shaped body such that the room provided between the shovel shaped body in the vicinity of the metal strip can be set to a desired value defining the room provided in the vicinity of the back-up roll. The at least one addi tional pressure means can be set independently, leading to an independent and pre defined room for the part of the work roll surface in the vicinity of the metal strip when in use and an independent and predefined room for the part of the work roll surface in the vicinity of the back-up roll when in use.

Using both pressure means and additional pressure means therefore define the room available to form a water cushion between the shovel-shaped body and the work roll which provides the cooling of the work roll. In this way the water cushion formed is more stable. So, by using both pressure means and an at least one addi tional pressure means, both the scraper and the one or more spacers can be set such that they are individually controlled. No unnecessary gaps are formed leading to loss of water of the water cushion, which in turn leads to an unstable water cushion and therefore unstable cooling. Using both pressure means and additional pressure means allow the force of the scraper and the one or more spacers on the work roll surface to be set to a predefined value and create a balanced cooling device having less wear.

It is preferable that the pressure means and the at least one additional pressure means are arranged to cooperate such that both the predefined force of the scraper and the predefined force of the one or more spacers on the work roll surface are as low as possible. As the predefined force can be set to any desired value, the prede fined force on the work roll surface of the scraper can be set equal to, higher or lower than the predefined force of the one or more spacers on the work roll surface. This has the advantage that, according to the specific cooling conditions, the wear on the scraper and the one or more spacers is as low as possible and uneven wear of both is also prevented. It can therefore also be set to the lowest force possible without sacrificing the spilling prevention function of the scraper and the stabilising function of the one or more spacers.

It is preferable that the pressure means and / or the at least one additional pressure means are air pressure means and / or a hydraulic pressure means. The pressure means and the at least one additional pressure means can be embodied in several ways. The inventor has found it beneficial to use air pressure means and hy draulic pressure means. For example the pressure means are air pressure means and the at least one additional pressure means are hydraulic pressure means. Natu rally other configurations and pressure means are possible.

It is preferable that the pressure means and the at least one additional pressing means are controlled automatically by a hot-rolling mill control system. The hot-rolling mill is controlled by a hot-rolling mill control system and therefore the control can be totally integrated in the control system making it possible for the operation to be con trolled automatically.

It is preferable that the pressure means and the at least one additional pressing means are controlled such that in idle time the predefined force on the scraper and the predefined force on the one or more spacers are minimised in order to prevent wear. When the hot-rolling mill is in idle time, meaning no processing is taking place, it is not required that the predefined forces are set to the normal processing values. Therefore it is beneficial to set them to the minimum value which further reduces the wear on the scraper and the one or more spacers.

It is preferable that the pressure means and the at least one additional pressure means are placed in an angle relative to each other of 70 - 120 degrees. To have the biggest effect of the cooperation between the pressure means and the additional pressure means they should not be lined up in the same plane, but be placed with an angle relative to each other. The inventor found it beneficial that the preferred angle is between 70 and 120 degrees.

The invention will hereinafter be further elucidated with reference to the drawing of an exemplary embodiment of a cooling device according to the invention that is not limiting as to the appended claims.

In the drawing:

figure 1 shows the device of the invention including the shovel-shaped body in relation to the work roll;

figure 2 shows the shovel-shaped body as an individual part;

figure 3 shows a detail of figure 1.

Whenever in the figures the same reference numerals are applied, these nu merals refer to the same parts. The figures show the configuration for top rolls, but naturally the same goes for the bottom rolls. This is merely a mirror image, as the person skilled in the art knows.

Figure 1 shows the cooling device 1 of the invention as part of a hot-rolling mill for a metal strip 10. The hot-rolling mill is designed to process a metal strip 10 and has at least one pair of work rolls 2 and as such is known to a person skilled in the art and therefore requires no further elucidation. Usually the hot-rolling mill is equipped with the same configuration on the other side of the metal strip 10. This is not shown for clarity purposes. The configuration further comprises a back-up roll 13. The work roll 2 has a work roll surface 2’. The cooling device 1 further comprises a shovel shaped body 3 which in itself comprises a plurality of openings 4 (better shown in figure 2). It further comprises a scraper 5 arranged to prevent the cooling fluid from spilling on the metal strip 10.

The scraper 5 is therefore arranged to contact a part of the work roll surface in the vicinity of the metal strip 6, when in use. The cooling device 1 is also equipped with one or more spacers 8, arranged to contact a part of the work roll surface in the vicinity of the back-up roll 7, when in use. Also shown are the pressure means 9 and an additional pressure means 1 1. They are arranged to cooperate with each other to press both the scraper 5 and the one or more spacers 8 against the work roll surface 2’ with a predefined force. As is shown by the arrows A and B in figure 1 , the pres sure means 9 are arranged to move to-and-fro the work roll surface 2’ indicated by arrow A. Furthermore it is arranged to move the shovel-shaped body 3 in an up and down movement relative to the metal strip 10 according to arrow B, following the con tour of work roll 2. The at least one additional pressure means 1 1 are arranged to move back and forth according to arrow C. When the pressure means 9 and the at least one additional pressure means 1 1 cooperate the shovel-shaped body 3 can move such that both the scraper 5 and the one or more spacers 8 are pressed against the work roll surface 2’ with a predefined force. Figure 3 shows the important parts in more detail. Although in figure 3 the work roll 2 is shown as being elliptical, it is clear that this is only because a part of the work roll 2 is shown.

The at least one additional pressure means 1 1 allow that a predefined room for the scraper 5 can be set which does not define the room for the one or more spacers 8 and vice versa. The at least one additional pressure means 1 1 can be set inde pendently, leading to an independent and predefined room for the part of the work roll surface in the vicinity of the metal strip 6, when in use, and room for the part of the work roll surface in the vicinity of the back-up roll 7, when in use. So, by using both pressure means 9 and an at least one additional pressure means 1 1 , both ends can be set such that they are individually controlled. This allows the contact at both ends to be set to a predefined force and create a balanced cooling device 1 having less wear. Since they are individually controlled, it can also be set such that both the pre defined force of the scraper 5 and the predefined force of the one or more spacers 8 on the work roll surface 2’ are as low as possible. This could be even lower when in idle time. The pressure means 9 and / or the additional pressure means 1 1 could be air pressure means and / or hydraulic pressure means.

Figure 2 shows the shovel-shaped body 3 as an individual part of the cooling device 1. The shovel-shaped body 3 in itself comprises a plurality of openings 4 ar ranged to project a cooling fluid on a work roll 2. Also the scraper 5 is shown, which is positioned at one end of the curved portion of the shovel-shaped body 3. The one or more spacers 8 are positioned at the other, or opposite end of the curved portion of the shovel-shaped body 3. In this configuration it is shown that the spacers 8 are placed at the extremities of the shovel-shaped body 3. The one or more spacers 8 are arranged to contact the work roll surface 2’ with a predefined force. The scraper 5 could be a mechanical scraper, preferably made of a rigid material. The angle be tween the pressure means 9 and the at least one additional pressure means 1 1 could be set at 70 - 120 degrees relative to each other.

Although the invention has been discussed in the foregoing with reference to exemplary embodiments of the invention, the invention is not restricted to these par ticular embodiments which can be varied in many ways without departing from the invention. The discussed exemplary embodiments shall therefore not be used to con- strue the appended claims strictly in accordance therewith. On the contrary, the em bodiments are merely intended to explain the wording of the appended claims without intent to limit the claims to these exemplary embodiments. The scope of protection of the invention shall therefore be construed in accordance with the appended claims only, wherein a possible ambiguity in the wording of the claims shall be resolved us- ing these exemplary embodiments.