AU749715B2 - A rolling line - Google Patents

Description

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AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

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Name of Applicant/s: Actual Inventor/s: Address for Service: Invention Title: Danieli C. Officine Meccaniche SpA Massimo Lestani and Roberto Nini BALDWIN SHELSTON WATERS 60 MARGARET STREET SYDNEY NSW 2000 'A ROLLING LINE' Details of Original Application No. 10078/97 dated 08 January 1997 The following statement is a full description of this invention, including the best method of performing it known to me/us:- File: 30300AUP00 -2- This invention relates to a rolling line for the rolling of long products. In particular, the rolling line is for rolling long products thereby to change the dimensions of each product from a respective starting dimension to a respective finished dimension.

The invention is applied to the iron and steel production field in the sector of the production of long products consisting of alloys containing iron in particular, but not limited to, bars, rods, or wire rods, whether round or of any other required cross-section.

Preferred embodiments of the invention enable the production, and, in particular, the finishing, of the products to be improved and make possible an increase in the output of the plant which incorporates the rolling line, an improvement of the surface and inner quality, and a reduction of the times for corrective work and maintenance on the line.

In the field of production, by rolling, of long products such as bars, rods, wire rods, i etc, the extensive competition between producers gives rise, increasingly, to the need to o •o meet very strict processing parameters to obtain products of a high quality at ever decreasing costs and in ever decreasing time periods.

More particularly, requirements of steelmakers, as taken into consideration by plant designers, involve meeting the following specifications: dimensional tolerances in a range between 0.08 mm. and 0.1 mm. over the ;••whole range of dimensions of rolled product (the range of dimensions in this type of ~plant being generally between 4.0 and 25 mm.); a speed of finishing of the product higher than 120 m/sec and even as high as 140 rn/sec; a production speed of the line of at least 120 tons/hr; a percentage of discarded material not greater than 3%; -3a plant usage factor of at least the ability to carry out a finishing process at a low temperature on a whole range of products so as to obtain a high surface, and inner, quality of the finished products.

All these specifications are not normally met as a whole in conventional rolling plants, or at least, are not met over the whole range of products which can be produced by a line.

This situation is due to a plurality of causes which arise mainly from the lay-outs of plants and from the rolling methods conventionally employed, particularly in respect of changing from one dimensional range of products to another.

The rolling methods in conventional plants, which include a great number of specialised finishing passes for each type of section, require the performing of frequent •and long processes for the changing of equipment, and these processes are time consuming and labour intensive, thus reducing the factor of exploitation, and therefore the efficiency, of the plants.

Moreover, in conventional rolling plants the need to perform, in separate steps, the cropping of the spirals at the leading and trailing ends of the coils which are formed from rolled products, requires the use of additional personnel with a resulting increase in costs o ••and in working times for the completion of the processes.

Furthermore, conventional rolling methods result in the need to discard a great 20 quantity of material, and this situation has become unacceptable in rolling plants.

It is an object of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.

According to the invention there is provided a rolling line for the rolling of long products thereby to change the dimensions of each product from a respective starting -4dimension to a respective finished dimension, the line being suitable for the respective starting dimension of each product to be a nominal sectional size of between 120mm and 180mm, the line including: at least one roughing assembly; two cantilever rolling blocks downstream of the at least one roughing assembly, each including successively-positioned rolling stands having alternate horizontal and vertical axes; a reduction/sizing assembly positioned downstream of the cantilever rolling blocks and having three rolling passes for reducing selected products passing along the line to their respective finished dimensions being between 20 mm and 25 mm; a fast pre-finishing block positioned such that the cantilever rolling blocks are disposed between the fast pre-finishing block and the at least one roughing assembly; r S a fast finishing assembly including two separate finishing blocks each having two

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S•rolling passes whereby the fast finishing assembly has four rolling passes, at least one of fees the reduction/sizing assembly and the fast finishing assembly including components and 0 .being associated with a quick-change device configured for selectively effecting the .0.0 quick changing of said components.

~Preferably, the rolling line includes a plurality of cooling units, the units having: 0 *water-spraying cooling elements; and

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20 shut-off elements to shut off water sprayed from said cooling elements, the cooling units being positioned between the fast pre-finishing block and the fast finishing assembly and the cooling elements and shut-off elements being configured to operate with a water pressure of about 6 bar.

Preferably, the rolling line is configured to apply tension to products passing along the line, the line preferably including a tension-uniforming device positioned between two said cooling units for rendering uniform the tension applied to products passing along the line.

The rolling line preferably includes a high-speed flying shears positioned upstream of the fast finishing assembly and configured to crop leading ends and trailing ends of products passing along the line.

The rolling line preferably includes a measuring assembly positioned at an outlet of the reduction/sizing assembly and configured for measuring dimensions of products passing along the line.

Preferably, each finishing block of the fast finishing assembly is associated with its own respective motor. In this case, said motors are preferably coupled by an electric control group.

:The rolling line preferably includes a plurality of drawing assemblies having 1 °15 adjustment systems configured for maintaining products passing along the line under tension between said drawing assemblies and for automatically adjusting to changes of the cross-sectional dimensions of products rolled while passing along the line.

The fast-finishing assembly is preferably suitable for reducing selected products to oo.

their respective finished dimensions being 4mm and S" 20 Preferably, said reduction/sizing assembly is selectively operable.

The rolling line according to embodiments of the invention includes, for all the ranges of products to be rolled, the following lay-out: -6a roughing assembly normally comprising from 10 to 18 rolling mill stands, depending on the dimension of the starting billet, which is normally between 120 mm.

and 180 mm.; two pairs of cantilever rolling blocks, each of which comprises two rolling mill stands with alternate horizontal and vertical axes; a selectively operable reduction/sizing assembly with three rolling stands; a fast pre-finishing block with a number of rolling passes between six and ten; a fast finishing assembly with four rolling passes, which comprises two blocks, each with two rolling passes.

A rolling line according to an embodiment of the invention is configured such that all the products which are to have finished dimensions in the range of between 4.0 mm and 20 mm follow the same processing line to substantially the same dimensions up to the last rolling pass of the pre-finishing block, and such that the final dimensions of these products are attained in the four rolling passes of the finishing assembly.

15 A rolling line according to an embodiment of the invention is configured such that **all the products which are to have finished dimensions in the range of between 20 mm and 25 mm are finished in the reduction! sizing assembly with three rolling passes, whereby the final dimensions of these products are attained in this assembly.

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The rolling line according to an embodiment of the invention includes an assembly for the fast changing of equipment, this assembly being associated with the two blocks of the finishing assembly for changing components which constitute equipment belonging to the finishing assembly.

Under advantageous conditions this situation enables the times for configuring the line to the desired rolling of products to be reduced appreciably and reduces downtimes -7and thus increases appreciably the relative proportion of exploitation time, and therefore the output, of the plant.

According to an embodiment of the invention, an assembly for the fast changing of components is included so as to function in cooperation with the pairs of cantilever rolling blocks which are positioned at the outlet of the roughing assembly.

According to an embodiment of the invention, an assembly for the fast changing of components is included so as to function in cooperation with the reduction/sizing assembly with three rolling passes, which is selectively operable and is located immediately downstream of the fast-rolling cantilever blocks. This assembly for the fast changing of equipment enables changing of components in respect of all three rolling passes, or of only two rolling passes, to be changed at the same time, or else the changing of components in respect of only one pass, depending on the rolling oo.:o requirements.

According to an embodiment of the invention an in-line system of cooling the °•15 rolled products being fed is included at least between the pre-finishing block and the **finishing assembly.

Under advantageous conditions, this cooling system lowers the temperature of the rolled products leaving the pre-finishing block and enables a finishing process to be carried out at a low temperature over the whole range of products.

S. °20 In particular, under advantageous conditions, a product can be finished at a temperature of about 750'C or even down to 700 0 C, and an excellent equalisation of the heat of the product can be achieved at the inlet of the finishing assembly, due to the sufficient distance, in an embodiment of the invention, between a last cooling box of the cooling system and the finishing assembly, this distance being enough to permit a -8required degree of stabilisation of the product in terms of temperature before the final reduction of the product.

Moreover, in an embodiment of the invention where all the products which are to have finished dimensions of between 4 mm and 20 mm are finished in the last four rolling passes downstream of this cooling system, these products are fed through the cooling system with a minimum cross-sectional size greater than that normally envisaged in conventional rolling trains and at a relatively low temperature.

This makes it possible to have more rigid and stable products travelling through the cooling line and also, under advantageous conditions, makes it possible to have a continual delivery of water in the cooling line, thus enabling each whole product from its leading end to its trailing end to be cooled in an even and controlled manner.

This situation represents a considerable advantage over conventional plants in which products having cross-sectional sizes below 8 mm are not stable during their travel through the cooling line owing to their modest section, to the high speed and to the •s15 high temperature, and therefore the products of conventional plants do not always permit continual delivery of water in the cooling line, for such delivery has to be shut off when the leading part of each product passes through.

This has the effect that the leading part of the product leaves the cooling line being sprayed with water at a temperature different from that sprayed on the rest of the product o 20 and the leading part has to be discarded from the coil with a resulting loss of material.

This loss of material is avoided, under advantageous conditions, in embodiments of the present invention, with the resulting advantage of reducing the length of the end segments of the rolled products not subjected to the cooling treatment and therefore 00having to be discarded from the coil.

-9- Furthermore, this situation, under advantageous conditions, also enables the working life of valves delivering the cooling water to be prolonged owing to the fewer cycles of opening and closing to be carried out over a period of time.

According to an embodiment of the invention a high-speed cropping shears is included in-line upstream of the finishing assembly, for the purpose of automatically removing the leading and trailing end segments of each product before sending the rolled product to the finishing step.

Thus the high-speed shears under advantageous conditions makes possible the elimination of separate cropping operations carried out in conventional rolling processes and thus achieves a considerable saving in respect of the labour force employed.

In addition, the wound coils of products thus produced are ready to be pressed, tied and despatched without undergoing any further manual processing.

According to an embodiment of the invention electronic-control drawing systems are positioned along the line to keep the product constantly under tension for adapting to °•15 any change of section and therefore to any change of relative speeds and tension.

Unless the context clearly requires otherwise, throughout the description and the claims, the words 'comprise', 'comprising', and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of "including, but not limited to".

•20 Preferred embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawing which shows, also by way of example only, a preferred lay-out of a rolling line.

The rolling line 10 shown in the attached figure is arranged for a billet having an initial square cross-section and having a starting dimension such that the sides of the square cross-section are about 160 mm in length. In a preferred embodiment, the rolling line 10 is suitable for billets where the sides are between 120 mm and 180 mm in length.

In another preferred embodiment, the line 10 is suitable for billets having rectangular cross sections.

This rolling line 10 comprises a roughing train assembly 11 including twelve rolling mill stands 12 with alternate horizontal and vertical axes. Generally, in preferred embodiments, there are 10 to 1 8 rolling mill stands depending on the initial size of the billets. In the present example there are 12 rolling mill stands.

The roughing train is followed by two fast cantilever rolling blocks 13 for performing variable reduction, each of which includes two rolling mill stands constituting rolling passes 14 having alternate horizontal and vertical axes.

Between the first fast cantilever rolling block 13a and the second fast cantilever o:oo rolling block 13b there is positioned a first loop-forming machine 15a, which can be disconnected from the remainder of the line. A second loop-forming machine which can also be disconnected from the remainder of the line, is included at the outlet of the second fast cantilever rolling block 13b.

Each of the cantilever rolling blocks 13 is connected to its own drive motor 16 through a double-ratio gear transmission 17.

The cantilever rolling blocks 13 are associated with a device 18 which provides for quick changing of rolling components which constitute equipment forming part of the S°cantilever rolling blocks. The device 18 allows a whole operation of changing this equipment to be carried out automatically in a very short time less than five minutes and probably less than four minutes.

-11- The cantilever rolling blocks 13a and 13b are substantially identical to each other and can be interchanged to increase the working flexibility of the rolling line In this example a reduction/sizing assembly 19 with three rolling passes is included in-line downstream of the second loop-forming machine 15b and can selectively be disengaged from the remainder of the rolling line 10 whereby the reduction/sizing assembly is selectively operable. In a preferred embodiment of the present invention, the reducing/sizing assembly 19 is effective for reducing products to their finished dimensions such that they have square or rectangular cross sections the sides of which are between 20 mm and 25 mm in length. To facilitate clarity in the description that follows, products reduced in this way are referred to below as a first group of the products passing along line The reduction/sizing assembly 19 is also associated with its own device 118 for fast-changing of components constituting equipment of the rolling passes. The device 118 is analogous to the device 18 but provides also for the selective disengagement of the reduction/sizing assembly 19 from the remainder of the rolling line Furthermore, the device 118 is configured for performing any of the following actions according to the particular rolling requirements: simultaneously changing the equipment constituting all three of the rolling passes of the reduction/sizing assembly S" 19; changing the equipment constituting only two of these rolling passes; or changing the equipment constituting only one of these rolling passes.

a. a The reduction/sizing assembly 19 is driven by motors A measuring assembly 21 to measure dimensions of the products being fed, and also to monitor surface faults, is included at the outlet of the reduction/sizing assembly 19 and is followed by a first fast cooling unit or assembly 22 employing water.

-12- The product leaving this fast cooling assembly 22 passes through a shears 23 performing cropping of the leading and trailing ends of the product and is then fed into a third loop-forming machine 24, which can selectively be disengaged from the remainder of the rolling line The product is then sent to a fast pre-finishing block 25, which in the present example comprises eight reduction rolling passes although generally, in preferred embodiments, it has between six and ten.

In an embodiment of the invention, the pre-finishing block 25 is configured to carry out an average percentage reduction of the cross-section of the rolled product of about between 14% and The products constituting a second group of the products passing along the line as distinct from the first group mentioned above, follow the same reduction process as one another from their entry into the roughing train 11 up to the last rolling pass of the pre-finishing block 25. The products of this second group are reduced to substantially the same dimensions as one another by the time they reach this position along the line They are then reduced to their respective final dimensions downstream of the prefinishing block 25 in a fast finishing assembly which is discussed below. These final dimensions are such that they have square or rectangular cross-sections the sides of 00 which are between 4 mm and 20 mm in length.

S- 20 Each relevant rolled product downstream of the pre-finishing block 25 undergoes a o• a fast cooling process, which involves two cooling units 26a and 26b for spraying water and which together form part of a cooling line.

A tension-uniforming device 27, to make the tension of the product uniform, is included between the two units 26a and 26b.

-13- The units 26a and 26b lower the temperature of the products. This is to permit finishing of all the products that is, the products destined for the entire range of finished dimensions at a low temperature. This enables a better surface, and inner, quality of the finished products to be achieved and also enables the parameters of tolerance in relation to the desired nominal dimensions, to be improved.

The cooling units 26a and 26b include water-spraying cooling elements that is, nozzles, and shut-off elements for shutting-off the water sprayed by the nozzles. These nozzles and shut-off elements function at a water pressure of about, or even somewhat below, 6 bar.

This low pressure allows for a situation where the initiation of vibrations is prevented at the position where each product travels through the cooling line, and as a result, each whole product, from its leading end to its trailing end, is evenly cooled.

Downstream of the cooling units 26a, 26b there is positioned a drawing assembly 28 with two rolls for performing drawing. At the outlet of the assembly 28 there is •.15 located, in-line, a high-speed flying shears 29 which crops the leading and trailing ends of the products. The flying shears 29 is associated with a scrap shears 30 downstream of the flying shears, which breaks up the cropped ends.

Since the products entering the cooling units 26a, 26b possess, for each intended •o.

finished dimension of the finished products, a minimum cross-sectional size more than that normally envisaged in conventional rolling trains, and since the products in respect of the present invention travel at a reasonably low speed; the end segments to be cropped are shorter than those of conventional rolling trains.

-14- The quantity of products discarded is therefore reduced to a value which is appreciably lower than and which represents an improved value as compared to that which can be achieved in conventional rolling trains.

Lastly, the products are delivered into the fast finishing assembly mentioned above, which is designated 31.

A preferred embodiment of the invention permits the temperature of products entering the finishing assembly to be in the range of about 700'C to 750 0

C.

The finishing assembly 31 comprises two finishing blocks 32, each of which includes two reduction rolling passes.

An embodiment of the invention permits the two finishing blocks 32 to perform a reduction which is variable according to the desired finished dimensions of the products.

To this end, the finishing blocks 32 are associated with a third quick-change device 218, which is suitable to perform changing of rolling components which constitute equipment of the finishing assembly 31, in a very short time.

C. C The percentage reduction of section achieved by the finishing assembly 31 is, for the entire second group of products, at least about 12% to 16%, and this enables dimensional tolerances to be achieved which are even smaller than the approximately S 0.1 mm required in the specifications normally stipulated by producers.

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S...o S" The inclusion of the quick-change device 218 in association with the finishing 20 assembly 31 enables a quick adaptation of the rolling line 10 to the various ranges of cross-sectional sizes to be achieved and, under favourable conditions, enables a relative proportional exploitation of the rolling line 10 of up to 94% or even more, as compared to values of about 85% to 87% of conventional rolling lines.

This enables the output of the plant to be increased appreciably and, at the same time, a smaller labour force to be employed for performing operations on the line The two finishing blocks 32 are driven individually by respective motors 33, through respective double-ratio gear transmissions 34.

The two motors 33 are coupled to each other by an electric control group governed by an automation system which governs the whole of the rolling line 10. The purpose of this is to enable an extremely accurate adjustment of the relationship of speed between the two finishing blocks 32 according to the required reduction of the products.

According to an embodiment, the pre-finishing block 25 includes a motor (not indicated) which is coupled to the two motors 33 of the finishing assembly 31 by means of an electric control group. The electric control group is governed by the automation system of the line 10, which enables accurate adjustment of the relationship of speed between the pre-finishing block 25 and the finishing assembly 31 according to the required reduction of the products.

•15 The units 26a and 26b include blocks, also referred to as boxes (not individually shown) in which water-cooling of the products takes place. Furthermore, the finishing assembly 31 includes rolling mill stands (not shown) a first of which is positioned at the inlet to the finishing assembly. It will be appreciated that the distance between the last •o.

S"of the water-cooling boxes and the first rolling mill stand is sufficient to allow the 20 controlling of heat of each respective product such that this heat is equalised throughout the whole product, when it reaches the inlet to the finishing assembly.

In a preferred embodiment, the delivery of water in the blocks or boxes is continual.

-16- In a preferred embodiment, the rolling line 10 is configured such that the second group of products referred to above passes through the finishing assembly 31 at a speed of about 140 m/sec.

A drawing assembly 35 with two rolls is included at the outlet of the finishing assembly 31 and advances the products to a further loop-forming machine 36.

All the drawing assemblies of the rolling line 10 including the drawing assembly 28 and the drawing assembly 35 are equipped with automated adjustment systems governed by the automation system of the line 10, for keeping the products under tension between the various assemblies and blocks, during every step of the method according to I 0 the embodiments of the invention being described.

Accordingly, and in particular, the drawing assemblies provide for adaptation of the line 10 to any variation in the cross-sections of the products during rolling.

Although the invention has been described with reference to specific examples it will be appreciated by those skilled in the art that it may be embodied in many other f 15 forms.

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Claims (8)

1. A rolling line for the rolling of long products thereby to change the dimensions of each product from a respective starting dimension to a respective finished dimension, the line being suitable for the respective starting dimension of each product to be a nominal sectional size of between 120mm and 180mm, the line including: at least one roughing assembly; two cantilever rolling blocks downstream of the at least one roughing assembly, each including successively-positioned rolling stands having alternate horizontal and vertical axes; a reduction/sizing assembly positioned downstream of the cantilever rolling blocks and having three rolling passes for reducing selected products passing along the line to their respective finished dimensions being between 20 mm and 25 mm; a fast pre-finishing block positioned such that the cantilever rolling blocks are o. disposed between the fast pre-finishing block and the at least one roughing assembly; S. 15 a fast finishing assembly including two separate finishing blocks each having two rolling passes whereby the fast finishing assembly has four rolling passes, at least one of the reduction/sizing assembly and the fast finishing assembly including components and being associated with a quick-change device configured for selectively effecting the quick changing of said components. S. 20 2. A rolling line according to claim 1, including a plurality of cooling units, the units having: water-spraying cooling elements; and shut-off elements to shut off water sprayed from said cooling elements, -18- the cooling units being positioned between the fast pre-finishing block and the fast finishing assembly and the cooling elements and shut-off elements being configured to operate with a water pressure of about 6 bar.

3. A rolling line according to claim 2 configured to apply tension to products passing along the line, the line including a tension-uniforming device positioned between two said cooling units for rendering uniform the tension applied to products passing along the line.

4. A rolling line according to any one of the preceding claims, including a high-speed flying shears positioned upstream of the fast finishing assembly and configured to crop leading ends and trailing ends of products passing along the line. A rolling line according to any one of the preceding claims, including a measuring assembly positioned at an outlet of the reduction/sizing assembly and configured for measuring dimensions of products passing along the line.

6. A rolling line according to any one of the preceding claims, wherein each finishing 15 block of the fast finishing assembly is associated with its own respective motor.

7. A rolling line according to claim 6, wherein said motors are coupled by an electric control group.

8. A rolling line according to any one of the preceding claims, including a plurality of 0:'i drawing assemblies having adjustment systems configured for maintaining products 20 passing along the line under tension between said drawing assemblies and for automatically adjusting to changes of the cross-sectional dimensions of products rolled while passing along the line. -19-

9. A rolling line according to any one of the preceding claims, wherein said fast- finishing assembly is suitable for reducing selected products to their respective finished dimensions being 4mm and A rolling line according to any one of the preceding claims, wherein said reduction/sizing assembly is selectively operable.

11. A rolling line substantially as herein described with reference to any one of the embodiments of the invention illustrated in the accompanying drawings and/or examples. DATED this 28th day of December 2000 DANIELI C. OFFICINE MECCANICHE SpA Attorney: JOHN B. REDFERN Fellow Institute of Patent and Trade Mark Attorneys of Australia of BALDWIN SHELSTON WATERS S. Co CO