CN1668394A - Method and plant for the hot rolling of rails - Google Patents

Abstract

A rolling mill for the production of rails comprising a reversible intermediate working section ( 3 ) which receives broken down bars from an appropriate upstream break down rolling station ( 2 ) and passes them to a downstream finishing station ( 4 ). The intermediate working section ( 3 ) comprises a first ( 30 ) and a second universal stand ( 32 ), a high edging stand ( 31 ) placed between the first and the second universal stands ( 30, 32 ). The three stands ( 30, 31, 32 ) are placed at such a distance between each other that the bar can be simultaneously held in all three said stands ( 30, 31, 32 ) during rolling. A method for the rolling of rails with such a plant comprises the following operations in order: a rolling passage ( U1 ) in the second universal stand ( 32 ); a rolling passage ( E1 ) in the high edging stand ( 31 ); a rolling passage ( U2 ) in the first universal stand ( 30 ).

Description

Method and apparatus for hot rolling rails

field of invention

The present invention relates to a method and apparatus for producing hot rolled articles such as metal beams, especially rails and similar rollable materials.

Background technique

It is known to carry out the hot rolling manufacture of rails in suitable rolling stands.

Rolling operations for rails generally consist of breaking operations of ingots or slabs on one or more breaking stations, optionally with intermediate passes, followed by finishing operations at a finishing station.

The development of high-speed railway lines requires their rails to have tighter machining tolerances than in the case of ordinary railway line rails.

The problem underlying the present invention is to provide a method and an apparatus for rolling rails which enable the production of rails of higher quality in terms of dimensional and surface tolerances, while limiting the number of rolling stands.

According to a first aspect of the invention, this problem is solved by a method for manufacturing rails or similar products by means of a rolling plant comprising a reversible intermediate section which receives a pre-roughed strip from a suitable upstream roughing station, in which After processing it is sent to a downstream finishing station, wherein the intermediate station includes:

The first and second universal bases;

A high vertical roll stand is arranged between the first and second universal stands.

The above-mentioned three stands are arranged at such a distance from each other that the strip is accommodated in all three stands simultaneously during rolling.

The method is characterized in that it comprises the following operations in the order shown:

the first rolling pass in the second universal stand;

The first rolling pass in the high vertical roll stand;

The first rolling pass in the first rolling stand.

According to a second aspect of the invention, the problem described in more detail above is solved by implementing the above method by using a rolling plant comprising a reversible intermediate section for receiving pre-roughed strip from a suitable upstream roughing station, After processing it is sent to a downstream finishing station, wherein the intermediate station includes a first universal stand and a high vertical roll stand arranged in sequence along at least one rolling axis. The apparatus according to the invention is characterized in that it also comprises a second universal stand arranged along at least one rolling axis, so that the high vertical roll stand is arranged between the first and the second universal stand, said three stands They are arranged at a distance from each other so that the steel bar is simultaneously accommodated in three stands during rolling.

The advantages of the above-mentioned method and equipment are not only good balance of good dimensional and surface tolerances, and limited number of rolling stands, but also high productivity.

The limitation on the number of frames results in a lower initial investment cost and lower cost of product changeover. In fact, the simultaneous rolling of the same bar with two or three stands can be done at a higher overall temperature than that of the unrolled stands, thus making it possible to reduce the number of rolling passes.

In addition, regarding the control of roll rotation speed and other processing parameters, the control of the three-stand intermediate rolling section is relatively simple.

According to a further aspect of the invention, said method for producing rails or similar products by rolling comprises a finishing operation of a steel strip which has been formed into a semi-processed rail, characterized in that said finishing operation comprises rolling on a universal stand pass, the universal stand is equipped with a first vertical roll capable of processing the bottom of the rail, a second vertical roll capable of processing the top (T) of the rail, and the first and second vertical rolls can simultaneously roll the top (T) and bottom (B).

Currently, in the rolling of rails, the finishing pass is performed on a semi-universal rolling stand equipped with a single vertical roll or sometimes in a high vertical roll stand.

This finishing method allows the rail to be manufactured with better dimensional accuracy, especially the height and shape of the finished rail top.

The preferred embodiment presented allows to achieve a good finished surface and further improves the dimensional accuracy of the rolled rail.

The finishing method according to a further aspect of the invention can be used both in combination with the intermediate rolling method according to the preceding aspect of the invention described above, and also in combination with the intermediate processing method of rails according to the prior art.

Brief description of the drawings

Other advantages of the present invention will be obvious to those of ordinary skill through the detailed description of the following embodiments in conjunction with the accompanying drawings, and said embodiments are non-limiting examples, wherein:

Fig. 1 shows schematically an embodiment of a rolling plant implementing the method according to the invention;

Fig. 2 shows schematically the sequence in which rolling operations are implemented in the plant of Fig. 1 according to an embodiment of the method of the present invention;

Fig. 3 schematically shows a sectional view of a finishing stand of the apparatus shown in Fig. 1 according to a first embodiment of the method of the present invention;

Fig. 4 schematically shows a sectional view of a finishing stand of the apparatus shown in Fig. 1 according to a second embodiment of the method of the present invention;

Fig. 5 schematically shows a sectional view of a finishing stand of the apparatus shown in Fig. 1 according to a third embodiment of the method of the present invention;

Fig. 6 schematically shows a cross-sectional view of a finishing stand of the apparatus shown in Fig. 1 according to a fourth embodiment of the method according to the invention.

Detailed Description of the Invention

In this specification, the expression "reduction ratio (reduction rate)" ρ refers to (usually expressed as a percentage) the reduction value of the cross-sectional area S of each steel bar subjected to each rolling pass compared with that before the rolling pass The ratio of the section area of the steel bar, ρ=(S _prior -S _after )/S _prior .

Fig. 1 schematically shows a preferred embodiment of a hot rolling plant for steel rails according to the invention.

For example, a steel bar produced from a continuous casting facility (not shown) is first rough-rolled at a first group of fracture stations 1, optionally at a second group of fracture stations 2; middle section. After leaving this intermediate section 3, the strip is fed to a finishing station comprising a finishing stand 4, and from there to successive work stations (plate cooling, heat treatment, etc.).

In this patent application, the wording "finishing stand" or "finishing station" refers to a stand on a rolling line that completes the final rolling pass and completes the final dimensional adjustment of the rail.

According to one aspect of the present invention, the intermediate section 3 includes a first universal frame 30 and a second universal frame 32 along the steel strip rolling line from upstream to downstream, and is arranged between the first and second universal frames 30 and 32 The second high vertical roller stand 31.

The first and second universal stands 30 and 32 are reversible with the high vertical roll stand 31 and are arranged along a single rolling axis, and the distance between them is set so that the three can simultaneously engage the same roll during rolling. Steel bar (except in this case, that is, a stand is undergoing a "dry rolling" pass, and there are at most two stands engaging a steel bar at the same time).

The distance between the first and second universal stands 30, 32 and the horizontal rolls of the vertical roll stand 31 is preferably as close as possible: this allows the completion of the various rolling passes at a higher average temperature, with fewer rolls or the like wear, allowing a higher reduction rate per pass and/or a small number of passes (in the particular example described, it was possible to reduce the passes to three).

According to the first aspect of the invention, the rolling section 3 completes the rolling of the half-processed strip outlined in the figure according to the method described below.

The semi-processed steel bar is subjected to a first rolling pass U1 in the second universal stand 32, wherein the rolls of the first universal stand 30 are initially opened and thus a first empty pass D1 is completed; the direction of advancement of the bar is then reversed , and the steel bar to be processed passes through the intermediate rolling section 3 again, undergoes the first rolling pass E1 in the first processing groove of the high vertical roll stand 31, and then undergoes the first rolling pass E1 in the first universal stand 30. Pass U2.

The high vertical roll stand 31 is movable between different positions, thereby allowing different grooves or rolling grooves to be configured along the rolling axes of the two universal stands 30, 32 to produce different high vertical rolling passes.

The first rolling pass U1 in the second universal stand 32 preferably performs a reduction ratio ρ1 that is greater than the reduction ratio ρ2 of the first rolling pass U2 in the first universal stand 30, preferably assuming that ρ1 approximates is equal to 20%, and ρ2 is approximately equal to 16%; however this value can also be varied and modified according to specific needs (such as shape and size of the rail to be rolled, temperature, etc.). ρ1 is preferably chosen between about 10% and about 30%, and ρ2 is chosen between about 3% and about 25%.

Before being subjected to the first rolling pass U1 in the universal stand 32, the strips from the two breakers 1 and 2 are preferably further rolled in the second rolling trough of the high vertical roll stand 31 E2 fracture; if possible, the intermediate section 3 is at such a distance from the breaking machines 1, 2 that the steel bars processed in the intermediate section 3 are no longer controlled by the rollers of the breaking machines 1, 2, and the operation of E2 can be canceled after one The other operations of the breakers 1, 2 which process the passes and reduce the overall rolling time are done nearby.

When the steel bar passes from downstream to upstream again, the intermediate section 3, along with the reverse movement of the steel bar relative to the first rolling pass U1 in the second universal stand 32, and the rolling in the high vertical roll stand 31 Before the first rolling pass E1, the steel bar is subjected to the second rolling pass U3 in the second universal stand 32 (the pass U3 is performed, and after the pass U1, the rolls of the stand 32 are closer): as above Described, the first rolling pass U2 in the first universal stand 30, the first rolling pass E1 in the high vertical roll stand 31 and the second rolling pass U3 in the second universal stand 32 can This is done in three stands 30, 31, 32 which simultaneously accommodate the steel rods (the rails generally have final lengths varying from 60m to over 100m; also shorter lengths for spare heads or other additional elements).

According to the working cycle described in FIG. 2 of the present invention, after the first rolling pass U2 in the first universal stand, the advancing direction of the steel bar is reversed again, and the steel bar undergoes the second rolling pass in the first universal stand 30. Rolling pass U4 (in the same rolling roll as pass U2, but it is pass U4, and the rolls of the stand 30 are closer at this time), sequentially on the stand 31 of the vertical roll stand The third rolling pass E3 is carried out in the three rolling grooves; the rolls of the second stand 32 are now open and without any rolling of the strip (second empty rolling pass D2 ), the strip is sent to the finishing station 4 .

Rolling pass U3 preferably performs a reduction ratio ρ3, ρ3 being between approximately 10% and 30%, in particular approximately equal to 16%, and rolling pass U4 performing a reduction ratio ρ4, ρ4 being between approximately 3% and approximately 20%. Between, especially approximately equal to 8%.

According to the above-mentioned preferred working cycle, the fracture and hardest rolling pass U1 (optionally U3) with the largest reduction rate is only carried out in the second universal stand 32, and at the same time, the pass U2 ( Optionally U4) is carried out in the first universal base 30: in this way, the maximum wear and initial deformation U1, U3 of the breaking operation are only included in the second universal base 32, while the successive ones are considered as pre-finishing passes The rolling passes U2, U4 are exclusively carried out in the first universal stand 30, so that they are subjected to only a small amount of wear and ensure that the tolerances of the shape and surface finish on the steel bar coming out of the section 3 are sufficiently accurate, relatively fracture and The roughing pass and the final pre-finishing pass are completed in the intermediate rolling section on the same universal stand. The equipment has a longer working life: in fact, in the working cycle of Fig. 2, the first universal mill The seat 30 compensates for the faster deteriorating shape deviation of the steel bar from the second universal frame 32 .

Using the method according to the invention, the surface finish of the rolled rail is better: in fact, the reduced wear in the processing of the stand rolls 30 enables the rolling of the rail for a longer period of time with respect to rolling installations of known type smooth surface.

The structure of the intermediate section 3 with basically only three stands does not require an overly complicated roll speed control system; the time for retooling can also be reduced, and the management of small batch production is simplified.

Compared with other devices, one can obtain the same quality and tolerances in the manufacture combined with a small number of housings, so that one saves the initial investment.

For example, operation with reversing stands ensures a more uniform temperature distribution on the strip compared to a continuous rolling process.

Preferably, the finishing station 4 is spaced from the intermediate section 3 at such a distance that the bar is not accommodated in three stand sections 3 and in the finishing station 4 simultaneously; in addition to allowing simultaneous execution with less dead time and intermediate rolling manufacturing and finishing, said method also eliminates the deformation of the steel bar that would occur if the bar were accommodated in both section 3 and station 4: in fact in this case, even with a suitable operating system The control, the speeds of the stands 30, 31, 32 and the finishing station 4 still produce more or less important relative offsets, whereby expansions, deformations and dimensional changes of the steel strip generally occur.

In current normal production, the finishing station 4 includes a semi-universal rolling stand (that is, has two horizontal rolls 40, 41 and a vertical roll 42, Fig. 3; the vertical roll 42 rolls and finishes the lower surface of the placed rail bottom ) or a high vertical roll stand (Figure 4).

According to a preferred embodiment of the method according to the invention ( FIG. 5 ), the finishing station 4 preferably comprises a universal stand with two horizontal rollers 400, 401 and two vertical rollers 402, 403, the vertical rollers 402 handling and finishing the rail B At the same time, the second vertical roller handles and refinishes the top T area of the semi-processed rail; the two vertical rollers 402, 403 refinish the bottom and top of the simultaneously processed rail.

The use of a universal stand with two vertical rollers (Fig. 5, 6) is a further factor to obtain more precise tolerances over the entire height of the rail. Still referring to Figure 5, generally the top T of the rail comprises a rollable central surface T1 on which the wheels of the railway vehicle rest, and two lateral flanks T2, T3 which are oriented generally rectilinearly or Oriented vertically or at a slight slope; the wheels of the railway vehicle rest transversely on the lateral flanks T2, T3.

The central rolling surface T1 and the two lateral flanks T2, T3 are connected by two arcuate portions T4, T5.

The vertical rolling roll 403 for deforming and refinishing the top T of the rail comprises a roll groove 404 which plastically deforms and reconditions the top T; the groove 404 comprises a central region which plastically deforms and reconditions the top The central rollable section T1, the two side surfaces arranged on either side of this central area, maintain and shape the lateral flanks T4, T5 of the top T of the rail.

Another roller 402 has a generally flat rolling surface to finish the underside of the bottom B of the rail.

The shape of the slot 404 allows maintaining and shaping not only the central rolling zone T1 of the rail top T, but also the top flanks T4, T5 with greater precision.

Going back to the rolls of the conventional semi-universal finishing stand in Figure 3, usually the difference between the different rotational speeds of the rolling groove at different points P1-P10 will be on the surface of the rolled steel strip, in some metal areas of the steel strip An undesired shifting effect occurs; for this reason the depth of the rolling groove must not be too great.

By comparing the groove sections of the rolls of Figures 3 and 5, it has been noticed that the roll of the Figure 5 type with the groove 404 does not cause too much staggering effect on the rail surface; because the staggering effect increases with the average groove diameter Decrease and increase, for the vertical rollers 402,403 it is best to choose a large diameter.

FIG. 6 shows another embodiment of a universal finishing stand with two vertical rollers 422 , 423 developed by the applicant.

In such an example, the groove 424 shaping the rail top T has a small depth and it has no lateral wings capable of shaping and maintaining the rail top lateral flanks T2, T3; the groove 424 is only rolled and finished in the rail top central region T1 ; In this way, the misalignment problem caused by the variation of rotational speed along the groove 404 surface is overcome.

The finishing stand of Figure 6 is itself also equipped with a second roller 422 to shape and precisely finish the underside of the bottom B of the rail.

The two vertical roll finishing stands described above can be used not only in finishing stations in the plant explained according to the invention, but also in plants of different types, for example with intermediate sections of known type. Regardless of the type of frame used for finishing (semi-universal, universal or vertical roll), the finishing pass UF in frame 4 (Fig. , in particular with a reduction ratio ρF equal to 2%: such a reduction ratio, particularly small, optionally in combination with the aforementioned pre-finishing operations performed in optional passes U2 and U4, compared to finishing methods of the known art , enabling fairly precise dimensional and surface finish tolerances and more stable finish times.

Many variations can be made to the embodiment described without departing from the scope of the invention: for example by adding or deleting rolling mills carrying out the individual passes. If the floor space in the building in which the equipment is housed requires, the number of passes the steel bar passes through the intermediate section 3 may also be an even number rather than an odd number as described above, so that the rail at the end of the rolling cycle starts from the same The side section 3 is discharged, and traverses the section 3 and continues downstream.

Every modification and change falling within the range equivalent to the claims is deemed to be embraced therein.

Claims (19)

1, a kind of method of making rail or similar products by steel rolling mill, this steel mill comprises reversible middle workshop section (3), this workshop section (3) receives the fracture steel bar from roughing station, suitable upstream (2), after to its processing it is delivered to finishing station, downstream (4), and wherein this centre worker station (3) comprising:

First (30) and second universal stand (32);

High vertical roll unit (31), it is arranged on first and second universal stand (30,32) between, above-mentioned three supports (30,31,32) are provided with such distance to each other, make described steel bar in rolling, be contained in all three supports (30 simultaneously, 31,32) in, the method is characterized in that to comprise following operation in the indicated order:

First rolling pass (U1) in second universal stand (32);

First rolling pass (E1) in high vertical roll unit (31);

First rolling pass (U2) in first universal stand (30).

2, the method for claim 1, it is characterized in that first rolling pass (U1) the execution minification (ρ 1) in second universal stand (32), this minification (ρ 1) is greater than the minification (ρ 2) of first rolling pass (U2) in first universal stand (30).

3, method as claimed in claim 2, the minification (ρ 1) that it is characterized in that first rolling pass (U1) execution in second universal stand (32) is between about 10% and about 30%, and the minification (ρ 2) that first rolling pass (U2) in first universal stand (30) is carried out is between about 3% and about 25%.

4, method as claimed in claim 3, it is characterized in that the minification (ρ 1) that first rolling pass (U1) in second universal stand (32) is carried out approximates 20%, the minification (ρ 2) that first rolling pass (U2) in first universal stand (30) is carried out approximates 10%.

5,, it is characterized in that first rolling pass (U1) that second rolling pass (E2) in the high vertical roll unit (31) is positioned at second universal stand (32) before as any described method in above-mentioned one or more claims.

6, as any described method in above-mentioned one or more claims, it is characterized in that first rolling pass (U1) of described steel bar in second universal stand (32) afterwards, first rolling pass (E1) in high vertical roll unit (31) is carried out the rolling of interior second rolling pass (U3) of second universal stand (32) before.

7, method as claimed in claim 6, the minification (ρ 3) that it is characterized in that second rolling pass (U3) execution in second universal stand (32) is between about 10% and about 30%.

8,, it is characterized in that the 3rd rolling pass (E3) in first rolling pass (U2) the back high vertical roll unit of execution (31) in first universal stand (30) as any described method in above-mentioned one or more claims.

9, as any described method in above-mentioned one or more claims, it is characterized in that first rolling pass (U2) in first universal stand (30) after, in first universal stand (30), carry out second rolling pass (U4) immediately.

10, method as claimed in claim 9 is characterized in that minification (ρ 4) that second rolling pass (U4) of carrying out carries out is between about 3% and about 20% in first universal stand (30).

11,, it is characterized in that the 3rd rolling pass (E3) in the high vertical roll unit (31) links to each other with second rolling pass (U4) of carrying out in first universal stand (30) in turn as any described method in above-mentioned one or more claims.

12, as any described method in above-mentioned one or more claims, it is characterized in that it comprises the operation that a series of cardinal principles are made of following rolling pass in the indicated order:

Second rolling pass (E2) in high vertical roll unit (31) of coming out from pre-thick rolling (2),

First rolling pass (U1) in second universal stand (32),

Second rolling pass (U3) in second universal stand (32),

First rolling pass (E1) in the high vertical roll unit (31),

First rolling pass (U2) in first universal stand (30),

Second rolling pass (U4) in first universal stand (30),

The 3rd rolling pass (E3) in the high vertical roll unit (31),

Rolling pass (UF) in the finishing station (4).

13, a kind of method by Rolling Production rail or similar products, comprise that being configured as half finishing of handling the steel bar of rail operates (UF), it is characterized in that this finishing operation (UF) comprises the rolling pass in the universal stand (4), this universal stand (4) is equipped with first edger roll (402 that can process rail foot (B), 422), second edger roll (403,423) that can machined steel tread portion (T), and this first and second edger roll rolling this top (T) and bottom (B) simultaneously.

14, method as claimed in claim 13, the minification (ρ F) that it is characterized in that finishing operation (UF) execution is between about 1% and about 15%.

15, as claim 13 and/or 14 described methods, it is characterized in that being suitable for processing half edger roll (403,423) of handling the top (T) of rail is suitable for the rolling rail that comprises top (T), this method also comprises:

But the central surface of a roll off (T1), it can vertically support the wheel of rolling stock,

Two lateral flanks (T2, T3), their relative vertical lines linear directional or vertically or with the slight draft orientation substantially when rail is installed, and can provide cross-brace to the wheel of rolling stock,

Two arc coupling parts (T4, T5), they each all central rollable surfaces T1 is connected to gradually described lateral flanks (T2, one of T3) on,

And can process half edger roll (403,423) of handling the top (T) of rail and comprise groove, this groove comprises middle section in turn, and also finishing central authorities can the section of rolling (T1) again in this zone energy plastic deformation.

16, method as claimed in claim 15, it is characterized in that to process half and handle the edger roll (403 at the top (T) of rail, 423) groove comprises being arranged on these middle section both sides and being suitable for keeping and moulding half handles lateral flanks (T2, two side surfaces T3) at rail top (T).

17, a kind of rolling equipment that is used to carry out one or more aforementioned claim methods, this equipment comprises reversible middle workshop section (3), it is used for receiving the pre-roughing steel bar from roughing station, suitable upstream (2), after to its processing, it is delivered to finishing station, a downstream (4), wherein this centre worker station (3) comprises, first universal stand (30) and the high vertical roll unit (31) that set gradually along at least one rolling axis, it is characterized in that also comprising second universal stand (32) that is provided with along at least one rolling axis, so this high vertical roll unit (31) is arranged on first and second universal stand (30,32) between, described three supports (30,31,32) be located at a distance from each other, thereby steel bar is contained in three supports (30 simultaneously in rolling, 31,32) in.

18, equipment as claimed in claim 17 is characterized in that three supports (30,31,32) of this intermediate rolling workshop section (3) one after the other are provided with, and can not insert other rolling support.

19, as claim 17 and/or 18 described equipment, it is characterized in that also comprising finishing station (4), this finishing station (4) comprises the finishing support with middle workshop section (3) the such segment distance in interval successively, when the finishing support carries out finishing passage (UF) to steel bar, arbitrary support (30 of workshop section (3) in the middle of steel bar can not be contained in, 31,32) in.

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