EP0043956B1 - Rolling mill for producing a hot-rolled strip - Google Patents

Description

The invention relates to a rolling mill for the production of hot strip with a roller table for transporting the hot strip to a reel device, wherein in the area in front of the reel device on both sides of the roller table guide rulers are arranged which converge in the transport direction to force the strip tip into a central position.

Rolling mills of this type are known per se. The slabs heated to a predetermined temperature in heating ovens are rolled out into strips and taken up at the end of the rolling mill by a coiler mandrel of a coiler and wound into coils. In front of the reel device, two guide rulers are arranged as infeed guides on both sides of the roller table, which converge in the direction of transport, i.e. are funnel-shaped and force the belt tip into a central position, i.e. center the incoming belt tip. In general, these guidelines have proven their worth.

With thin hot strips, i.e. Hot strips below a thickness of approximately 2.5 mm, however, have problems: For technical reasons, hot strips show slight thickness fluctuations after they have passed through the rolling stands, which is noticeable in thin hot strips in such a way that the beginning of the strip in the level of the hot strip when leaving of the last roll stand can be curved. Such a curved beginning of the band is called the beginning saber. It can also happen that the hot strip is transported off-center.

Since - as already mentioned - the guide rulers are funnel-shaped, the incoming strip tip forms an obtuse angle with them, which must not exceed a certain limit angle if the hot strip is to enter the coiler machine without any problems. In the case of thin hot strips, it turns out that this limit angle is often exceeded as a result of the starting saber formed or the off-center transport. As a result, the band tip turns over and the band material that follows is folded like an accordion and must be removed as scrap. Due to the high rolling speeds of today's strip lines, subsequent strips cannot be finished rolled and must be deposited as scrap. The malfunctions caused can only be remedied with great expenditure of time and material.

The invention has for its object to design rolling mills of the type mentioned in such a way that even with thin hot strips, i. H. Hot strips below a thickness of approximately 2.5 mm, in particular those with an initial saber, the strip tip being centered in the middle of the coiler mandrel.

This object is achieved according to the invention in that, in order to support the centering effect of the converging area of the rulers, at least one linear drive is arranged in front of it, which generates two magnetic fields, the forces acting on the belt each having a component directed towards the center of the roller table and a component directed in the direction of transport , through which the beginning of the belt is grasped and aligned with the center of the roller table. These measures ensure that the linear drive of the belt tip gives a focusing thrust towards the center of the roller table without contact if the center of the belt tip deviates from the center of the roller table. A focusing thrust towards the center of the roller table is to be understood in the sense of the invention that the linear drive works according to the principle of a pair of linear drives, each of which exerts a thrust on the belt, which is directed towards the center of the roller table, wherein in each case the direction of the thrust and the direction of transport of the belt likewise form an angle other than zero.

The use of linear drives in rolling mills is already known per se (DE-AS 2 251 592). These linear drives serve, on the one hand, to transport the rolling stock, for example foils, and so-called control linear motors are additionally provided for central control across the material transport. From this publication it is also known to use linear drives when threading the foils into reel machines. For this purpose, the swiveling wrapping devices of the reel machine have linear drives. After aligning the pivotable threading device onto a gap upstream of the take-up reel, the tip of the film is shot through the gap by acting on the linear drive. The problem underlying the invention is not addressed, however. This also applies to the use of linear drives in rolling mills known from DE-OS-2 325 327. The belts to be transported are suspended by the linear drives over their entire length. At the same time, there can be a focusing effect for aligning the belts to the center of the roller table.

In a further embodiment of the invention, a device for producing a cooling pad for the hot wide strip from a gaseous and / or liquid medium is arranged in the area of the linear drive on the inlet side of the flat material. Through these measures it is achieved that in the case of the hot broadband of large heat capacities, i.e. e.g. When heavy strips pass through the hot strip mill between the linear drive and the side of the hot strip facing it, a cooling cushion is generated which absorbs and transports away a considerable proportion of the radiant heat radiated by the hot strip. At the same time, the padding compensates for the slight difference in level between the roller table level and the level of the linear drive.

According to the cooling pad made of water, water vapor, air or another liquid or gaseous medium, such as. B. kerosene, nitrogen exist. The sliding and / or protective pad for the flat material can consist of water, air, oil, an emulsion or an inert gas. The main advantage of a liquid cushion is that the springing of heavy strip material onto the linear drive is dampened. In the case of thin hot strip, the same effect can be achieved using a gaseous medium, which then also forms a protective gas atmosphere. The pad for the hot wide strip can also have a pure sliding function, it can also have a protective function and in the latter case ensures that e.g. There are no scratches on the sensitive surfaces of thin hot strip.

According to the invention, the device can emit a liquid medium which evaporates in the area between the hot broadband and the linear drive, so that a considerable proportion of the radiant heat is used for the heat of vaporization. For this purpose, the device can e.g. Dispense water. The formation of a sliding cushion is of importance if linear drives are provided instead of one or more rollers of the roller table of the belt line, so that a rolling transport of the hot wide strip is not possible in this area. The gas or liquid medium forms a sliding cushion based on the aquaplaning principle. This medium has the task, in particular in the case of thin hot strips, to prevent the hot strips from making contact with the surface of the linear drives during transport as a result of the spring deflections which always occur, which would lead to scratches or scratches on the surface of the strip material. Such tapes are known for further processing, e.g. in the automotive industry, no longer usable and must be sorted out.

According to the invention, the device has a cover arranged in the plane of the cover plate of the linear drive with outlet openings for the liquid or gaseous medium. Here it must be ensured that on the one hand a sufficiently strong cushion is formed, and on the other hand it must also be ensured that the medium does not cool the hot wide strip in the sense of a structural influence. In order to achieve a uniform production of the cushion according to the invention, in a further embodiment of the invention the axes of the outlet openings are arranged inclined to the surface of the cover in such a way that the hot wide strip moves the medium into the area between the underside of the strip and the cover plate and the cover due to its movement . These measures ensure that only the inlet side of the hot strip is fed in as a gaseous or liquid medium between the underside of the hot strip and the linear drive, which is sucked into the gap between the strip and the linear drive by the movement of the strip.

According to yet another advantageous embodiment of the invention, the cover has a bevel on the inlet side of the hot wide strip to reject the edge of the warm wide strip in the transport direction, so that if the incoming hot wide strip is deflected (ski formation), the strip cannot jam.

In a still further embodiment of the invention, the cover and the linear drive are designed as a unit that can be raised and lowered. This is particularly advantageous if, for example, the use of linear drives is avoided when transporting heavy material and care must be taken to ensure that damage to the linear drive and the cover is prevented by the incoming front edge of the material.

In a further embodiment of the invention, the heat-insulating cover plate consists of wear-resistant as well as magnetic and electrical insulating material.

These measures on the one hand create a heat shield for the linear drives, whereby the choice of wear-resistant material also provides mechanical protection for the linear drives in the event that the belt tip does not remain in the plane defined by the rollers of the roller table, for example by executes pendulum movements due to mechanical vibrations and the like in the direction of the linear drives. The additional requirement that the cover plate should act both magnetically and electrically isolating means that the traveling fields of the linear drives do not exert any shear forces on the cover plates.

In normal operation of strip lines, the rolling of thin hot strips in the sense of the invention and thicker hot strips alternate with one another in an irregular sequence, the linear drives remaining switched off when the thicker strips are being rolled, since these do not have the effects that occur with the thinner strips. The radiation exposure from the thicker hot strips is, however, considerably greater than that from the thinner hot strips. For this reason, in a still further embodiment of the invention, cooling channels are formed between the slot locking wedges of the linear drives and their cover plates, so that the external thermal load on the linear drives can be reduced even further. These cooling ducts also dissipate a significant proportion of the waste heat from the linear drives when generating the traveling fields in addition to the conventional cooling circuits.

• Fig. 1a, 1b in schematischer Darstellung die Funktionsweise des Linearantriebes,
• Fig. 2 eine Draufsicht auf eine Walzstrasse mit der Anordnung des Linearantriebes,
• Fig. 3 einen Schnitt durch einen Linearmotor nach Fig.2,
• Fig. 4 im Ausschnitt eine Walzstrasse mit dem Ausführungsbeispiel der Einrichtung zur Erzeugung der Polster in perspektivischer Darstellung und
• Fig. 5 einen Schnitt durch das Ausführungsbeispiel der Fig. 4 in vergrösserter Darstellung quer zur Transportrichtung.

The invention is explained in the drawing using an exemplary embodiment. Show it:

• 1a, 1b in a schematic representation the operation of the linear drive,
• 2 is a plan view of a rolling mill with the arrangement of the linear drive,
• 3 shows a section through a linear motor according to FIG. 2,
• Fig. 4 in detail a rolling mill with the embodiment of the device for producing the cushion in a perspective view and
• Fig. 5 shows a section through the embodiment of Fig. 4 in an enlarged view transverse to the direction of transport.

1a and 1b serve to explain the principle of the solution: The center line of the roller table and the direction of transport of the hot wide strip are shown schematically by the arrows a, b. The linear drive, which consists of two linear motors 2 'and 2 "at the same distance from the center line of the roller table (arrow a, b), is arranged below the hot strip. Due to the different hatching of the surface of the linear drive 2' covered by the hot strip or 2 "is indicated schematically that the traveling fields of these two linear drives do not run in the same direction, ie ideally are directed in opposite directions. A thrust of each linear drive is aligned with the hot strip 2 ", the thrust of the linear drive 2" being denoted by D. Both drawers each have a component in the direction of transport. In the case of a symmetrical arrangement of the hot strip to the center line of the roller table, pushes of the same size are exerted on the strip in accordance with the covered areas of the same size of the two linear drives. If the band runs eccentrically, as shown in FIG. 1b, the covered areas are of different sizes, so that, according to the illustration in FIG. 1b, the linear drive 2 'exerts a greater thrust C' than the linear drive 2 ", which produces a thrust A resulting thrust is thus exerted on the hot strip with a focussing effect, ie in such a way that the beginning of the band is centered, ie focused, on the center of the roller table a, b. This means that the beginning of the band is always automatically centered without any additional device of the roller table is centered or focused if the distances a 'and b' of the two linear drives 2 'and 2 "from the center line a, b are the same. It is therefore possible, by means of a displaceably guided arrangement of these two linear drives, to adjust them so that they exert a focusing thrust on the belt in the direction of the center of the roller table.

FIG. 2 shows a plan view of a rolling mill corresponding to FIG. 1, the linear drive consisting of three pairs of linear motors 2 ′, 2 ″ according to FIGS. 1a, 1b arranged between the rollers of the roller table. The linear drives of each pair each have the same Distance to the center line a, b of the roller table, the distances between the pairs being different from this center line. The same parts are designated by the same reference numerals. The windings of the linear drives of each pair are designed and switched such that thrust components in the direction of the arrows shown be generated.

Fig. 3 shows a section through a linear drive. With 13 the winding is designated, which is arranged in slots 14. These grooves are closed in the direction of the band by so-called groove locking wedges 15. A cover plate 16, which consists of a highly wear-resistant material which additionally has a magnetic and electrical insulating effect, is arranged above these slot lock wedges. Cooling channels 19 are additionally formed between the cover plates and the slot wedges. The arrangement of the linear drives is such that the surface of these cover plates runs below the level of the belt contacted by the rollers.

In order to save energy and better control of the cooling problems, the linear motors can work in intermittent operation, the linear drives in question being switched off again each time the strip tip has passed through.

FIG. 4 shows a detail of a belt line in the area of a linear drive 2 in a perspective view. The rollers of the roller table driven by electric motors 9 are designated by 8, the electric motors being shown for only one roller for the sake of clarity. The rollers are mounted in bearing blocks, which are arranged on a profile 10. As can be seen from this FIG. 4, a linear motor is arranged on a profile instead of the one roller. The device according to the invention for producing the upholstery is designated by 36, which is shown schematically and forms a structural unit with the linear drive. The flat material is transported in the direction of the arrow, i.e. H. across the axis of the rollers and across the linear drive.

5 shows a section through the linear motor and the device according to the invention according to FIG. 4. The winding 13, which is arranged in slots 14, is designated by 13. Above the grooves, the cover plate 16 is arranged, which consists of a highly wear-resistant material that also acts magnetically and electrically insulating. The arrangement of the linear drive is such that the surface of this cover plate runs below the plane of the belt contacted by the rollers to form the gap. The device 36 according to the invention has a cover 37 which is arranged in the same plane as the cover plate 16 and forms a structural unit with the linear drive.

The cover 37 merges into the bevel 38 on the inlet side of the material and has openings 39 which are supplied with the medium via the collecting line 40.

As can be seen from FIG. 5, the axes of the openings 39 are inclined to the transport direction of the flat material in such a way that the emerging medium is entrained by the flat material to form a wedge-shaped cushion. The direction of transport of the non-numbered flat material is indicated by the arrow. The linear drive and the device according to the invention form a structural unit, which with means not shown lifting / lowering device is height adjustable.

Claims (8)

1. A rolling mill train for producing hot wide strip, having a roller table (3) for conveying the hot wide strip to a winding device (4), guides (6, 7), which converge in the conveying direction in order to force the head of the strip (1) into a central position, being arranged laterally on both sides of the roller table in the region upstream of the winding device, characterized in that, in order to assist the centring effect of the converging area (5) of the guides (6, 7), there is disposed upstream of the said converging area (5) at least one linear drive (2', 2") which generates two magnetic fields, whose forces acting upon the strip each comprise one component which is orientated towards the centre of the roller table and one component which is orientated in the conveying direction, and by which the beginning of the strip is detected and aligned to the centre of the roller table.

2. An apparatus according to Claim 1, characterized by a device (36) disposed in the region of the linear drive (2', 2") on the entry side of the hot wide strip in order to produce a cooling cushion for the strip from a gaseous and/or liquid medium.

3. An apparatus according to Claim 2, characterized in that the device (36) has a covering (37) disposed in the plane of the cover plate (16) of the linear drive with outlet openings (39) for the liquid or gaseous medium respectively.

4. An apparatus according to Claim 3, characterized in that the axes of the outlet openings (39) are inclined with respect to the surface of the covering (37) in such a way that by virtue of its movement the hot wide strip draws the medium into the area between the underside of the strip and the cover plate (16) and the covering.

5. An apparatus according to any one of Claims 3 to 4, characterized in that the covering (37) has an inclined portion (38) on the entry side of the hot wide strip in order to catch the edge of the strip.

6. An apparatus according to any one of Claims 3 to 5, characterized in that the heat-insulating cover plate (16) consists of wear-resistant and magnetic and electrical insulating material.

7. An apparatus according to any one of Claims 3 to 6, characterized in that cooling ducts (19) are formed between the slot wedges (15) of the linear drive (2', 2") and the covering plate.

8. An apparatus according to any one of Claims 3 to 7, characterized in that the covering (37) and the linear drive (2', 2") are constructed to as to be vertically displaceable as a structural unit.

Images