EP3027331B1 - Casting and rolling plant and method for producing slabs - Google Patents

Description

The invention relates to a casting and rolling plant with a strip casting machine and a method for producing pre-strip. Specifically, the invention relates to small caster rolling mills, so-called micromill plants, for the production of flat steel with an annual production between 350,000 and 700,000 t of carbon steel. The plant concept according to the invention is characterized by low investment and production costs, rapid project implementation with a short return on investment and a compact plant layout. The plant according to the invention is particularly suitable for steel producers in regions where so far no flat steel production took place and where a specialization to regional requirements should take place.

Cast rolling with strip casting machines are known in the art in principle. A comprehensive overview of the basics of strip casting is still available today Spitzer et al., Development of the DSC Strip Casting Process, Stahl and Eisen 121 (2001) No. 5 , DSC stands for Direct Strip Casting. From this article strip casting machines are known with a cooled conveyor belt and wherein the range from the steel task to hot rolling is housed, so that a protective gas atmosphere can be adjusted. The casting machine described there has a casting speed of up to 60 m / min. and produces a cast strand with a casting thickness of 8 to 15 mm. The strip casting machine downstream is a roller table and after the roller table follows a continuous in-line rolling. The rolling stand allows a reduction in thickness z. B. to 8 mm. After rolling, the steel strip is wound into a coil.

Further state of the art casting toggle systems with strip casting found for. B. in the DE 197 58 108 C1 or in the WO 2011/061262 A1 ,

Similarly, the WO 2010/066412 A1 a casting mill with a strip casting machine. The strip casting machine follows in the casting direction a roller table with a temperature homogenization zone, a temperature setting device, a mass flow control, a second temperature setting device and a rolling stand, a pair of scissors and a reel. A disadvantage of this continuous in-line rolling device, that the slab in the rolling stand only one stitch and thus only a reduction in thickness can be subjected before being wound up as a pre-strip on the reel.

An alternative plant concept with a strip casting machine is from the European patent specification EP 1 827 720 B1 known. Specifically, this patent discloses a caster in which follow after the strip casting a temperature homogenizer, a roughing stand, a pair of scissors and a first take-up device in the casting direction. To further reduce the thickness downstream of a Steckel mill is provided in the casting direction and the Steckel rolling mill below a cooling section and finally a coiler. To operate the Steckel mill, it is necessary that the coils produced by means of the first coiler be implemented in a first winding furnace located upstream of the Steckel mill before the metal strip of the coil can first pass through the Steckel mill for a first pass. Although the implementation of the coils or metal strips allows a temporary storage of coils or metal strips in a warehouse; However, this interruption of the casting-rolling process time and energy is lost, the latter in particular because the coils may need to be reheated in the winding furnace before entering the Steckel mill.

The German patent application DE 10 2004 057 427 A1 discloses a caster with an arcuate continuous casting machine and downstream in the casting machine unit for combined straightening and conveying the casting strand.

The international patent application WO 2011/158091 A2 and the European patent application EP 0 449 004 A2 each discloses a casting mill with a casting machine for casting a cast strand. The casting machine is a pair of scissors arranged for dividing the casting strand in slabs of predetermined length. The pair of scissors is a temperature-homogenizing device and this downstream of a Steckel mill for rolling the slabs to metal strips of predetermined thickness.

The preambles of claims 1 and 9 are based on the above WO 2001/158091 A2 ,

Based on this prior art, the invention has the object, a cast rolling and a method for producing slabs using a strip casting machine such that the casting mill can be made more compact and that in the manufacturing process time and energy can be saved.

The object is achieved by the device technology by the claimed in claim 1 casting rolling. This is characterized in that the casting machine is designed as a strip casting machine with a circulating cooled conveyor belt for casting the casting strand with a casting thickness between 10 and 20 mm; that between the output of the strip casting machine and the temperature homogenizing means a Multirollenglätteinrichtung is arranged; and that between the exit of the temperature homogenizer and the Steckel mill a roller table is provided for feeding the slabs directly into the Steckel mill.

In the context of the present description, the word "Gießstrang" for the cast product between mold and scissors; the word "slab" is used for the cast product between scissors and Steckel mill and the word "Vorband" for the cast product between Steckel mill and reel. Slabs are produced by dividing the casting strand; Pre-bands are produced by reducing the thickness of the slabs with at least one stitch.

The claimed plant concept has the advantage that behind the temperature homogenizing device, the slabs can be introduced directly into the Steckel mill and subjected to a first pass there without previously requiring a winding of the slabs. A roughing stand is not provided and not required. By saving the Vorgerüstes and a take-up device for winding the slabs from the temperature-homogenizer, the system can be made more compact and investment costs can be saved. In addition, this system concept is very energy efficient because no significant temperature losses occur between the temperature homogenizer and the Steckel mill, such as by interim storage or wrapping of coils, as is known in the prior art.

According to a first embodiment of the invention, the Steckwalzwerk upstream and downstream, in each case based on the casting direction, winding furnaces, so-called Steckel assigned. Both Steckel each have only one winding device and are each only designed to wind the pre-strip after a pass of the Steckel mill and for dispensing the pre-strip to the Steckel mill for the following stitch. In particular, the upstream wind-up furnace is not designed to receive the slabs, e.g. from the temperature homogenizer. It has for this purpose no second winding device or no second station, which would allow the winding of the slabs from the temperature-homogenizing device and which would further allow the conversion of the coil thus produced for feeding the slabs to the Steckel mill.

The shears for dividing the cast strand cast by the casting machine into slabs of predetermined length may be disposed between the multi-roll smoother and the entrance of the temperature homogenizer or between the exit of the temperature homogenizer and the Steckel mill.

Between the output of the temperature homogenizer and the Steckel mill, an induction heating device is preferably arranged for heating the slabs to a temperature suitable for the Steckel rollers.

The above object of the invention is further achieved by the method claimed in claim 9. The advantages of this process solution correspond to the advantages mentioned above with respect to the claimed cast roll mill.

The method provides that the casting strand with a casting belt speed of 5 to 25 m / min. is poured. The method according to the invention and the associated cast roll plant according to the invention are in particular provided for producing carbon steel pre-strips.

Further advantageous embodiments of the claimed casting and the claimed method are the subject of the dependent claims.

• Figur 1 die erfindungsgemäße Gießwalzanlage; und
• Figur 2 die erfindungsgemäße Bandgießmaschine im Detail

zeigt.The invention is a total of 2 figures attached, wherein

• FIG. 1 the cast roll mill according to the invention; and
• FIG. 2 the strip casting machine according to the invention in detail

shows.

The invention will be described in detail below with reference to the said figures in the form of embodiments. In both figures, the same technical elements are designated by the same reference numerals.

FIG. 1 It shows the casting roll plant 100 according to the invention. It comprises, as seen in the casting direction R, a melt delivery system 105, a strip casting machine 110, a multi-roll smoothener 120, a shears 130, a temperature homogenizing furnace 140, optionally an induction heater 150, a roller table 155, a Steckel mill 160, a Cooling section 170 and, for example, a coiler 180. The individual components of the casting rolling mill will be described in detail at least partially.

The melt delivery system 105 consists essentially of a refractory lined or separately dumped position Heatable melt container, which the liquid metal, ie the melt, via a discharge nozzle using the force of gravity on the conveyor belt 118, see FIG. 2 guiding strip caster 110. A level measuring system, in FIG. 1 not shown, ensures a constant melt level in the melt container and thus a constant flow of melt on the strip casting machine 110. The distribution of the melt over the casting width via flow guide elements (in FIG. 1 not shown) in the melt delivery system 105 or via arranged guide systems. These guide systems can conduct the melt with the aid of electromagnetic traveling fields or by the use of gas, which is passed through nozzles on the melt surface. The combination of several melt container with each other is possible. The flow guidance elements also extend beyond the melt delivery system into the region of the circulating conveyor belt 118 of the strip casting machine 110.

The strip casting machine 110 consists, as in FIG. 2 The transport belt 118 is preferably made of steel with a thickness of less than 3 mm. In the FIG. 2 shown smaller of the three rollers 115 ensures a uniform tension of the band. The lateral boundary of the strip casting plant is occupied by two horizontally encircling water - cooled dam block chains, in FIG. 2 Not shown. The conveyor belt is from below via spray nozzles, in FIG. 2 also not shown, cooled in the melt feed area with specific watering densities between 80 and 300 l / s / m ² . Until the belt outlet the Wasserbeaufschlagungsdichten be returned to values between 10 and 100 liters / sec / m ² . By virtue of the spray-cooling container, which is arranged almost air-tight beneath the belt and comprises the rollers 115 and support grids, the belt cooling is operated with preferably> 100 m / bar negative pressure. The outside prevailing air pressure thus ensures the flat pressing of the metal strip on the support means between the two large rollers 115th The strip casting machine 110 according to the invention has a strip contact length of less than 7.5 m, the strip contact length being measured as the distance between the centers of the two large rolls 115. The casting speeds realized with the strip casting machine 110 are between 5 and 25 m / min, depending on the casting thickness.

The strip casting machine 110 is the Multirollenglätteinrichtung 120 downstream in the casting direction R. In the multi-roll smoothing device 120, the cast strand is guided to improve its flatness with at least three pairs of rolls 124. The pairs of rollers are preferably driven individually. A reduction in the thickness of the casting strand generally does not take place in the multi-roll smoothing device.

The example subsequent scissors 130 cuts the cast strand in slabs of predetermined length and decouples the previous casting process from a subsequent rolling process.

In the casting direction R behind the multi-roll smoothing device 120, preferably also behind the shears 120, the temperature homogenizing device 140 is arranged, which is typically designed as a tunnel furnace. The inductive heating downstream of the furnace, which is provided only as an option, optionally provides for an increase in the temperature of the slabs and / or for a temperature compensation over the length of the slab before the slabs enter the downstream Steckel mill (160). The Steckel mill produces the desired final thickness with three, five, seven or more passes. The Steckel mill (160) is followed, as already mentioned above, in the casting direction by the cooling section 170 and the reel 180 for winding the pre-strips into a collar 250.

From a process engineering point of view, the casting roll plant according to the invention thus formed has the advantage that the slabs, after passing through the temperature homogenizing device 140, can be fed directly into the Steckel rolling mill 160 without any loss of time or energy or without heat loss Perform a first pass without having to be wound up first. At most, the induction heater 150 and / or the scissors 130 are arranged between the temperature homogenizer 140 and the Steckel mill 160.

LIST OF REFERENCE NUMBERS

100

continuous casting and rolling

105

Melt application system

110

strip caster

115

big roles

118

coated conveyor belt

120

Multirollenglätteinrichtung

124

three pairs of roles

130

scissors

140

Temperature-homogenizing

150

induction heating

155

roller table

160

Steckel mill

162

coiler furnace

164

coiler furnace

170

cooling section

180

coiler

200

cast strand

210

slab

220

opening act

250

Federation

R

casting

Claims (15)

1. Casting and rolling plant (100) comprising
   a casting machine for casting a cast strip (200);
   shears (130) for dividing up the cast strip into slabs (21) of predetermined length;
   a temperature homogenisation device (140); and
   a Steckel rolling mill (160) for rolling the slabs to form pre-strips (220) of predetermined thickness;
   characterised in that
   the casting machine is constructed as a strip casting machine (110) with a circulating cooled transport belt (118) for casting the cast strip (200) with a cast thickness between 10 and 20 millimetres;
   a multi-roller smoothing device (120) is arranged between the outlet of the strip casting machine (110) and the temperature homogenisation device (140); and
   a roller path for feeding the slabs directly to the Steckel rolling mill (160) is provided between the outlet of the temperature homogenisation device and the Steckel rolling mill.
2. Casting and rolling plant (100) according to claim 1, characterised in that the winding furnaces (162, 164) associated with the Steckel rolling mill (160) upstream and downstream thereof each have only one winding device and are each constructed only for winding up the pre-strip from the Steckel rolling mill (160) and delivering the pre-strip to the Steckel rolling mill.
3. Casting and rolling plant (100) according to one of the preceding claims, characterised in that an induction heating device (150) is arranged between the outlet of the temperature homogenisation device (140) and the Steckel rolling mill (160).
4. Casting and rolling plant (100) according to any one of the preceding claims, characterised in that the multi-roller smoothing device (120) comprises at least three roller pairs (124), of which at least one roller pair is driven.
5. Casting and rolling plant (100) according to any one of the preceding claims, characterised by a cooling path (170) downstream of the Steckel rolling mill.
6. Casting and rolling plant (100) according to claim 5, characterised by a coiler (180) downstream of the cooling path (170).
7. Casting and rolling plant (100) according to any one of the preceding claims, characterised in that the strip casting machine (110) has a strip contact length of less than 7.5 metres.
8. Casting and rolling plant (100) according to any one of the preceding claims, characterised in that the shears (130) for dividing up the cast strip into slabs of predetermined length are arranged between the multi-roller smoothing device (120) and the inlet of the temperature homogenisation device (140) or between the outlet of the temperature homogenisation device (140) and the Steckel rolling mill (160).
9. Method of producing slabs, comprising the following steps:

   producing a cast strip (200);

   homogenising the temperature of the cast strip (200);

   dividing up the cast strip into slabs before or after the homogenisation;

   after temperature homogenisation: introducing the slabs directly into a Steckel rolling mill (160), so as to there be subjected to a first pass, before they are fed for the first time to a winding furnace of the Steckel rolling mill; and

   thickness reduction of the slabs in the Steckel rolling mill with at least three passes to a desired thickness to form a pre-strip (220);

   characterised in that

   the production of the cast strip (200) is carried out by strip casting, wherein the cast strip (200) is cast with a thickness between 10 and 20 millimetres; and

   the cast strip (200) is smoothed before its temperature is homogenised.
10. Method according to claim 9, characterised in that the casting speed of the cast strip is between 5 and 25 metres per minute.
11. Method according to claim 9 or 10, characterised in that the slabs are heated again, preferably inductively, after the temperature homogenisation, but before entry thereof into the Steckel rolling mill (160).
12. Method according to any one of claims 9 to 11, characterised in that the cast strip prior to entry thereof into the Steckel rolling mill is divided up into slabs of predetermined length.
13. Method according to any one of claims 9 to 12, characterised in that the cast strip (200) consists of carbon steel.
14. Method according to any one of claims 9 to 13, characterised in that the pre-strips are cooled after exit thereof from the Steckel rolling mill.
15. Method according to claim 14, characterised in that the pre-strips are wound up to form a coil (250) after they have been cooled.

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