EP2555884B1 - Method for the flying changing of working rolls in continuous casting and rolling installations and hot strip rolling mills using a hold-down roller - Google Patents

Abstract

The invention relates to a method of flying changing of working rolls in continuous casting and rolling installations and hot strip rolling mills, in particular in continuous hot strip rolling mills, wherein for exchange of working rolls by opening a rolling stand, those are disengaged from a to be rolled hot strip. According to the invention a regulated strip tension that can substitute the tension of the open rolling stand, is applied to the to-be-rolled hot strip with at least one hold-down roller that is introduced in a rolling line.

Description

The invention relates to a method for flying work roll change in cast rolling and hot strip mills, in particular continuous hot strip mills according to the preamble of claim 1 (such, eg JP 56/144805 A ).

The work rolls of a rolling mill are subject to natural wear, which can lead to loss of quality at the surface of the rolled strip.

To avoid this, a change of work rolls is necessary from time to time.

During hot rolling, the strip to be rolled must be heated to the required temperature before being rolled, unless it is rolled directly from the casting heat.

When using a shorter furnace without buffer or omission of the furnace due to the fully continuous casting rolling must be stopped in full-continuous rolling operation of the casting operation for a change of work rolls. This is a production loss can not be avoided.

Fully continuous casting rolling operation with long casting sequences is not possible without loss of quality at the surface of the strip.
In cold rolling operation, these problems do not arise, ie here the belt is stopped and then performed the roll change.
In CSP continuous operation, this is not possible because the casting process is directly coupled with the rolling process and can not be stopped. If the casting process were stopped, this would immediately lead to the casting demolition and the production process would be interrupted.

Therefore, if a work roll change must be performed during casting, it is necessary to use it during rolling, i. So to carry out while the tape is running.

A roll change can only be done with the mill stand open.

If the affected rolling stand were to be opened, rolling would no longer be carried out in this rolling stand and therefore no reduction in thickness would be made. To compensate for this, the decrease in the open rolling mill would have to be distributed to the surrounding rolling stands, i. during the roll change, the rolling mills in the remaining meshing frame would additionally have to take over the rolling work of the opened roll stand. The possibility of strip tension control, which is normally taken over in a continuous hot strip mill by a loop lifter arranged between two successive rolling stands, would be lacking. This would not be possible due to the open mill stand. If one of the loop lifters arranged in front of or behind the opened roll stand was still active, the strip would possibly be pressed against the upper work roll of the opened roll stand. In that case, a work roll change would not be possible.

Procedures for changing from work rolls are from the publications JP 56 144805 A . JP 59 070412 A and JP 63 171204 A known.

The DE 195 40 978 A1 describes a production plant for the continuous or discontinuous rolling of hot strip with the ability to perform a work roll change on a rolling stand or a roll stand group, while the other rolling stands are continuously in operation.

The object of the invention is to provide an improved method for flying work roll change in cast rolling and hot strip mills.

This object is achieved according to the invention with a method for flying work roll change in cast rolling and hot strip mills, especially continuous hot strip mills, with the replacement of the work rolls by opening the roll stand these can be brought out of engagement with the hot strip to be rolled, characterized in that on the hot rolled strip to be rolled before and / or after entering the open mill stand via at least one insertable into the rolling line hold-down a controllable, the strip tension of the opened rolling stand Replacing strip tension can be applied.

If a roll stand for roll change is opened, the upper work roll of the open roll stand must be free and can no longer hold the strip down. This effect could be exacerbated if the looper normally arranged between the rolling stands would push the hot strip upwards.
In order to maintain the strip tension, the hold-down function is taken over by a hold-down roller which cooperates with the loop lifter. Since the space between the rolling stands are very limited, this hold-down role is run in a particularly narrow design.

It makes sense to perform a tape tracking during rolling. This serves to identify the band area, which was rolled during the roll change. This information is needed if, during the roll change, e.g. the temperature or thickness control for process reasons (limits) or e.g. could not be sustained due to rolling mill set failures. This results in a devalued or discarded piece rolled strip, which is to be separated in the further processing of the error-free tape. This is easier if the beginning and the end of this error band area are already known.

When changing the roll, it should be noted, moreover, that the temperature control remains during the rolling process. In order to ensure this, it may be necessary to regulate the cooling or heating within the rolling train during the roll changing operation.

• Figur 1 den normalen Walzvorgang bei geschlossenen Walzgerüst,
• Figur 2 den Walzvorgang bei einem für den Walzenwechsel geöffneten Walzgerüst und aktiver Niederhalterolle und in
• Figur 3 ist eine weitere Niederhalterolle im Auslaufbereich des Walzgerüstes aktiv, um einen Kontakt des Bandes zur oberen Arbeitswalze des geöffneten Walzgerüstes sicher zu vermeiden.

The method according to the invention will be explained below with reference to the drawings.
Showing:

• FIG. 1 the normal rolling process with closed mill stand,
• FIG. 2 the rolling process at a roll stand opened for roll change and active hold-down roll and in
• FIG. 3 a further hold-down roller is active in the outlet region of the roll stand, in order to reliably avoid contact of the strip with the upper work roll of the opened roll stand.

Between the rolling stands 1, 2 and 3 are the usual loop 4, over which the strip tension between the rolling stands is adjustable. In the normal rolling process, as in the FIG. 1 has been shown, neither arranged in front of the roll stand 2 hold-down roller 5 is still - if any - arranged after the rolling stand down holding roller 5 'in engagement with the hot strip. 6

For example, to change the work rolls in the middle stand 2, the rollers must be driven up, as the FIG. 2 shows.

Since the hot strip then has no contact with the work rolls, or may have, at least provided in front of the roll stand 2 hold-down roller 5 is active, together with the hold-down role associated with loop 4, so that the hot strip - without touching the work rolls - can be passed through the open rolling stand with the appropriate strip tension.

The flying change of the work rolls themselves can be carried out with conventional means.

Thus, for example, the pair of work rolls is guided by means of specially shaped rails in the rolling stand during the extraction or insertion into the rolling stand so that the upper roller lifts and both rollers do not touch the tape located in the street.

Before the roll change, a rolling program change takes place.

The Bandzugregelung between the rolling stands done by the hold-down invention.

Alternatively, a changing device can be moved in front of the rolling stand to be changed. On the device, the new rollers are stored. The old rolls are picked up and after transverse shifting, the new rolls are pushed into the mill stand.

Claims (4)

1. Method for flying working roll change in casting-rolling plants and hot-strip rolling trains, particularly continuous hot-strip rolling trains, wherein for exchange of the working rolls these can brought out of engagement with the hot strip, which is to be rolled, by opening the roll stand, characterised in that a regulable strip tension replacing the strip tension of the opened roll stand can be applied to the hot-strip, which is to be rolled, before and/or after entry into the opened roll stand by way of at least one holding-down roller introducible into the rolling line.
2. Method according to claim 1, characterised in that tracking of the strip in order to identify the strip region which was rolled during the roll change is carried out during the rolling.
3. Method according to one of the preceding claims, characterised in that temperature guidance by regulation of the cooling or heating within the rolling train is maintained during the roll change.
4. Method according to any one of the preceding claims, characterised in that the hot strip to be rolled is guided in common by the holding-down roller and a loop lifter arranged between the roll stands.

Images