EP0062697A2 - Process and walking-beam furnace for the heating of products used in ferrous metallurgy - Google Patents

Abstract

In order to achieve uniform furnace outlet temperatures for iron and steel products, in particular billets and slabs that enter a walking beam furnace (1) at different starting temperatures, the warmer products are fed outside the furnace in the longitudinal direction and into the furnace with the help of an outside furnace beam conveyor (9, 10) inserted laterally through various oven inlet openings (12, 13, 14), which are determined on the basis of the temperature of the products.

Description

The invention relates to a method and a walking beam = furnace for heating iron and steel products, such as billets, slabs, blocks or the like, which have different furnace inlet temperatures and / or different cross sections, in particular different thicknesses, and / or different qualities and / or each other =. differentiate on the basis of any other parameter that requires heating times of different lengths.

The improvement in the quality of the products obtained by the continuous casting process makes it possible in many cases to refrain from checking these products. This control requires the products to be cooled to temperatures that approach room temperature. This simplification also offers the possibility, which is very favorable from the point of view of energy saving, to include the heating and compensation furnaces still warm products to be fed directly from the continuous caster. The feed possible _k = eit the furnace in these products is, however, prevented that the known walking beam furnaces are designed to accommodate products with substantially the same kiln inlet = temperatures. The products which enter the known furnaces at a temperature which differs significantly from the average temperature therefore leave the furnace at a temperature which is lower than the temperature required for the rolling process, or are heated to an unacceptably high degree and begin to melt. In order to remedy this disadvantage as far as possible, the operation of the rolling mill provided in connection with the walking beam heating furnace has to be adapted to the operation of the continuous casting plant in such a way that the hot products reach the furnace without stays of varying duration and, consequently, without different cooling.

However, compliance with this condition presents practical difficulties, particularly in the plants which have a single continuous casting mold and a single rolling line. Because of these difficulties, in order to achieve a uniform temperature of the heated ironworks products, it is sometimes even preferred to completely cool down all the products supplied by the continuous casting plant and thereby to forego the advantages of charging the furnace with the products that are still hot.

The present invention has the task of eliminating the disadvantages listed above and a method for Developing heating of iron and steel products in walking beam furnaces, which makes it possible to load the furnace with successive products, such as billets, slabs, blocks or the like, which have different temperatures and / or different cross sections, in particular different thicknesses, and / or have different qualities, but at the outlet of the furnace the heated products have a substantially uniform temperature suitable for the rolling process. The method according to the invention is therefore intended to enable an elastic connection between the rolling mill arranged downstream of the walking beam furnace and the system upstream of the furnace.

The method according to the invention is characterized in that at least some of the products to be heated are pushed outside the oven in the longitudinal direction thereof and in the same direction of advance of the products inside the oven and laterally in the oven in various, based on the temperature and / or the cross-section, in particular = the strength, and / or the quality and / or any other parameter of the products determined, changing places accordingly. According to another feature of the invention, at least some of the products fed inside the furnace, as soon as they reach the desired furnace outlet temperature, are carried out laterally out of the furnace in correspondingly variable locations and then outside the furnace in its longitudinal direction and in the same feed direction the products are advanced further inside the furnace.

To carry out the method according to the invention, the invention provides a walking beam furnace, which is essentially characterized in that it has a plurality of lateral furnace inlet openings = consecutive in the longitudinal direction and / or several lateral furnace outlet openings which follow one another in the longitudinal direction of the furnace, and on at least one side of the furnace, in addition to the furnace in the region of the furnace inlet openings and / or the furnace outlet openings, there is a conveyor for the products that is external to the furnace and extends in the longitudinal direction of the furnace, which is synchronized with the furnace-type walking beam conveyor or coordinated with it and Feeds products in the same direction and at the same speed of the internal walking beam conveyor, whereby insert means for introducing the products into the oven through any of the lateral oven inlet openings and for transferring the products from the external conveyor to the inside of the oven n Walking beam conveyor and / or ejection means for pushing the products out of the oven through any of the lateral oven outlet openings and for transferring the products from the inside walking beam conveyor to the outside conveyor, as well as control and control means for classifying the products to be heated and / or of the products heated in the furnace based on their temperature and / or their strength and / or their quality and means for introducing the products to be heated into the furnace based on their arrangement either directly through the first furnace inlet opening or for redirecting the products to the furnace external conveyor and their introduction into the furnace with a greater or lesser delay through one of the successive lateral oven inlets = openings aligned with a vacant idle space on the inner walking beam conveyor and / or means for the execution of the heated products from the oven due to their classification either through the last oven outlet = opening or with a more or less large advance through one the upstream, lateral furnace outlet = openings on the assigned furnace outer conveyor are provided.

In terms of construction, the walking beam furnace can be designed in various ways with a conveyor which is assigned according to the invention and which is external to the furnace and is synchronized. So e.g. the outer conveyor, which is assigned to a plurality of successive, lateral furnace openings, can be provided only on the furnace inlet side or only on the furnace outlet side or both on the furnace inlet side and on the furnace outlet side. The successive lateral oven inlet or oven outlet openings can be designed in such a way that they only allow one product to pass through at a time, or they can have a width such that each of them is the inlet into the oven and / or the outlet allows the oven of one product each in several different positions, offset in the longitudinal direction of the oven. In the borderline case, even a single, lateral furnace inlet opening and / or a single lateral furnace outlet opening can be provided, which extends over the entire slopes of the assigned outer conveyor.

Both the external conveyor and the assigned ones Insertion or ejection means can be designed in different ways. In a preferred embodiment, the furnace-outer conveyor consists of a step-type conveyor, in particular a walking beam conveyor, which is designed similarly to the inside walking beam conveyor. The insertion means for introducing the products from the lateral outer conveyor into the oven and / or the ejection means for pushing the products out of the oven onto the lateral outer conveyor can consist of at least one axial loading button.

Any means for heating the products transported on the aforesaid external conveyor can be provided in the area of the external, lateral, on the oven inlet side and / or on the oven outlet side, to e.g. to prevent or restrict the cooling of these products and / or to achieve real preheating or reheating of the products. For this purpose, at least one conveyor provided outside the walking beam furnace can be inventively = according to the invention in a corresponding, preferably heat = insulated and expediently e.g. be arranged with the help of the exhaust gases from the walking beam furnace heated chamber.

These and other characteristics of the invention and the advantages achieved thereby result in more detail from the following description of a walking beam furnace according to the invention, which is shown, for example, in plan view and partly = in section in the single figure of the drawing.

In the drawing 1 is the chamber of one for heating iron and steel products e.g. Stick certain walking beam = furnace. With 2 the fixed beams and with 3 the walking beams of the walking beam conveyor arranged inside the furnace 1 are designated.

The direction of the incremental transverse axial advancement of the billets in the furnace 1 by the lifting conveyor 2, 3 is indicated by the arrow 4. At the inlet end of the furnace 1, a transverse roller table 5 is provided in the interior of the furnace, the rollers of which are driven by assigned motors 105. A similar, cross-directional roller table 6 is also provided inside the furnace at the outlet end of the furnace 1. With 106 the drive motors of the rollers of this = roller table 6 are designated. The billets are axially pushed out of the furnace in the direction of arrow 8 through a lateral outlet opening 7.

At the inlet end of the furnace 1, the wall of the furnace chamber opposite the lateral furnace outlet opening 7 has a plurality of furnace inlet openings 11, 12, 13, 14 which are successive in the longitudinal direction of the furnace and are dimensioned such that a single billet at a time axially through each furnace inlet opening can be introduced into the furnace 1. The lateral oven inlet openings are consecutive in the longitudinal direction of the oven, i.e. arranged in the feed direction 4 of the billet inside the furnace.

The distance between the central axes of the successive, lateral oven inlet openings 11, 12, 13 and 14 corresponds to one feed step or more feed = steps of the billet inside the furnace 1 through the furnace-internal walking beam conveyor 2, 3. The first lateral furnace inlet opening 11 is aligned with the inlet roller = aisle 5, while the subsequent lateral furnace inlet openings = 12, 13, 14 are aligned to the positions assumed by the billets on the fixed beams 2 of the furnace 1 in the course of the feed are arranged.

In the area of the lateral furnace inlet openings 11, 12, 13, 14, in addition to the furnace 1, an outer walking beam conveyor 9, 10 is provided, which extends parallel to the inner walking beam conveyor 2, 3 over part of the furnace length. The feed direction 15 of the outer walking beam conveyor 9, 10 corresponds to the feeding direction 4 of the inner walking beam conveyor 2, 3.

With 9 the fixed beams of the outer walking beam conveyor = rers 9, 10 are designated. The oven-external conveyor 9, 10 is assigned to a transverse loading roller table 16 with motor-driven rollers, which is arranged in alignment with the first oven inlet opening 11 and the subsequent inlet roller table 5 lying inside the oven 1. The furnace outer walking beam conveyor 9, 10 is arranged in a chamber 17, which can also be thermally insulated. The furnace = outer walking beam conveyor 9, 10 and the inside of the walking beam = beam conveyor 2, 3 have the same feed step and are synchronized with each other.

The ones to be heated, especially directly from one The billets supplied in the continuous casting plant are fed in the direction of the arrow 18 and are aligned with their longitudinal axis in this direction of the arrow, and they run into the feed roller table 16 through a side loading opening 19 provided in the chamber 17.

With the same quality and the same strength or the same cross-section, the supplied billets are checked and classified based on their temperature. On the basis of their temperature, the billets are introduced into the oven through the lateral furnace inlet opening 11, 12, 13, 14 which corresponds to a position on the heating curve corresponding to the temperature of each individual billet. In particular, the colder billets are fed directly from the loading roller table 16 through the first oven inlet opening onto the subsequent inlet roller table 5 into the oven and then removed from this inlet roller table 5 through the walking beams 3 of the inside walking beam conveyor 2, 3 and gradually transversely axially conveyed in the feed direction 4 over the entire length of the furnace 1. The coldest billets therefore remain in furnace 1 for the longest possible dwell time and consequently experience the greatest warming.

The warmer billets, on the other hand, are stopped on the loading = roller table 16, then removed from this roller table by the walking beams 10 of the outer walking beam conveyor 9, 10 and then gradually conveyed transversely axially in the feed direction 15 by this outside conveyor, which is the feed direction 4 of the billets inside of the furnace. For everyone so redirected and billets advanced from the outer walking beam conveyor 9, 10 remain empty space on the inner walking beam conveyor 2, 3 in the succession of the billets which are advanced inside the furnace 1. The positions that the billets on the fixed beam 2 of the inner stroke = beam conveyor 2, 3 can be aligned with the positions that the billets on the fixed beam 9 of the furnace = outer walking beam conveyor 9, 10 can take. A billet picked up by the outer walking beam conveyor 9, 10 and the corresponding, released Zeerplatz on the inner walking beam conveyor 3 move as a result = synchronously and in alignment with each other in the feed = directions 15 and 4.

When an initially warmer stick, and therefore on the furnace = outer walking beam conveyor 9, 10, which is moved axially axially, reaches a point in the longitudinal direction of the furnace from which the heating of this stick inside the remaining partial length of the furnace would bring about a furnace outlet temperature of the stick, which essentially the furnace = outlet temperature of the coldest, directly inserted through the first lateral furnace inlet opening 11 into the furnace = the mentioned warmer stick is also inserted axially into the furnace 1 through one of the further, lateral furnace inlet = openings 12, 13, 14. This introduction of the billet in the furnace 1 from the furnace outer stroke = beam conveyor 9, 10 to the inner walking beam conveyor 2, 3 through one of the side furnace inlet openings 12, 13, 14 is carried out with the aid of at least one axial loading button 20 which enters the chamber 17 from the the furnace 1 opposite Side engages through openings 21 arranged in alignment with the furnace inlet openings 12, 13, 14. The billets are preferably introduced into the furnace 1 through the lateral furnace inlet openings 12, 13, 14 at the moment when the inside of the lifting beam 3 and the outside lifting beam 10 are in their lowered position and the stick on the respective fixed beam 2 , 9 lie. In this case, the inside and outside of the fixed bars 2 and 9 are suitably profiled and form transverse guides 22 which are aligned with one another for the billets in the region of each lateral oven inlet opening 12, 13, 14.

It is obvious that each space on the outer lifting beam conveyor 9, 10 occupied by a billet always corresponds to a free, moving empty space on the inside walking beam conveyor 2, 3, so that when the warmer billets are introduced late through one of the furnaces = inlet openings 12, 13, 14, which are downstream of the first furnace inlet = opening 11 for the direct introduction of the billets into the furnace, no interference can occur. It is also evident that the billets exit through the furnace outlet opening 7 in the same order in which they are fed to the furnace in the direction of arrow 18 on the feed roller table 16, the furnace outlet temperatures of the billets being substantially the same and corresponding to the rolling temperature.

The classification of the billets on the basis of their temperature can also take place automatically and can, for example, on the basis of a single temperature measurement on the feed path of the billets to the furnace with the aid of an automatic control device which takes into account the cooling curve of the billets or on the basis of several, immediate and successive temperature measurements, for example in the billet positions aligned with the individual lateral oven inlet openings 12, 13, 14.

The control means form part of a control arrangement which controls the drive of the motor-driven roller tables 5, 16, the closing and opening movements of the doors of the furnace inlet openings 11, 12, 13, 14, the actuation of the loading buttons 20 and the movements of the furnace interior and the furnace exterior lifting beams 3, 10 controls.

The invention also makes it possible, using the same walking beam furnace, to heat not only iron and steel products with different furnace inlet temperatures, but also or only products with different thicknesses or different cross sections and / or products of different quality to the same furnace outlet temperature. In this case, the control and classification system is designed in such a way that it not only determines the temperature of the individual, supplied products, but also or only their thickness or their cross section and / or their quality, in order to determine the = to determine the furnace inlet opening 11, 12, 13, 14 through which each individual product must be introduced into the furnace in order to achieve the desired furnace outlet temperature.

To limit the cooling of the billets or the like, which are pushed forward with the help of the outer walking beam conveyor 9, 10 = before they are pushed through one of the successive = the lateral furnace inlet openings 12, 13, 14 into the furnace, the chamber 17, in which the furnace = outer walking beam conveyor 10 is housed, not only be heat-insulated but also heated, in particular = with the help of the exhaust gases from the walking beam furnace 1. In this case, the chamber 17, which contains the outer walking beam conveyor 9, 10 , be seen as a prechamber to walking beam furnace 1, this prechamber 17 and furnace 1 having different heating curves, which are in the area of the merging of the products concerned, ie Cut into the furnace 1 at the transfer point of the products from the pre-chamber 17.

To insert the billets through the lateral furnace inlet openings 12, 13, 14, several axial loading pushers, in particular one axial loading lever in the area of each furnace = inlet opening 12, 13, 14, or a single one, mounted on a trolley, alternately coaxial to the individual ones Furnace inlet openings 12, 13, 14 adjustable axial drawer = pusher 20 may be provided.

The invention can be used not only in the introduction of the iron and steel products to be heated into the walking beam furnace, but also in the execution of the heated products from the walking beam furnace. This means that instead of the transverse axial transport of the initially warmer billets outside the furnace in its longitudinal direction Direction and the axial introduction of these billets into the furnace with a more or less great delay in different places along the furnace, depending on the temperature and / or the cross section and / or the quality of the billets, so that they are in the same place are carried out at substantially the same temperature from the furnace, the above-mentioned billets can be introduced into the furnace in the same place in the usual way and can be carried out with more or less lead in different positions along the furnace as soon as they have the same aim Reach the furnace outlet temperature, after which the billets carried out are then transported transversely axially outside the furnace in the longitudinal direction thereof until they are brought together with the billets advanced inside the furnace.

Of course, the invention can be used both in the introduction of the products to be heated into the oven and in the execution of the heated products from the oven.

The invention can be used in conjunction with any lifting beam, regardless of its structural design, the drive means of the lifting beam and the heating and control means of the furnace.

In particular, the invention is suitable for use in connection with already existing walking beam furnaces for the purpose of converting them into furnaces according to the invention, since the furnace changes required for this are irrelevant and only require the existence of a sufficiently large free space to the side of the stove.

Claims (14)

1. Method for heating by means of walking beam furnaces of iron and steel products, such as billets, slabs, pre = blocks and. Like., Which have different starting temperatures and / or different cross-sections, in particular different thicknesses, and / or different qualities, characterized in that at least some of the products to be heated outside the furnace in the longitudinal direction and in the same feed direction of the products inside of the furnace and laterally introduced into the furnace in various places which are determined by the initial temperature and / or the cross-section, in particular the thickness and / or the quality and / or any other parameter of the products, and which change accordingly will. 2. Method for heating by means of walking beam furnaces of iron and steel products, such as billets, slabs, pre = blocks and. Like., Which have different starting temperatures and / or different cross-sections, in particular different thicknesses, and / or different qualities, in particular according to claim 1, characterized in that the products advanced inside the furnace as soon as they have the desired furnace outlet = reach temperature, carried out laterally out of the oven in correspondingly variable places and then pushed further outside the oven in its longitudinal direction and in the same feed direction of the products inside the oven. 3. The method according to claim 1 or 2, characterized in that the products are advanced in the same cycle and with the same step size both inside and outside the furnace such that each space occupied by a product outside the furnace has a free empty space inside of the furnace. 4. The method according to any one of the preceding claims, characterized in that the products advanced outside the oven are heated to prevent their cooling or for the purpose of preheating and / or reheating them. 5. walking beam furnace for heating iron and steel products such as billets, slabs, blooms and. Like. With the method according to any one of claims 1 to 4, characterized in that there are several, later in the furnace longitudinal direction successive furnace inlet openings (11, 12, 13, 14) and / or several, lateral, in the longitudinal direction of the furnace has successive furnace inlet openings and on at least one side of the furnace next to the furnace in the region of the furnace inlet openings (11, 12, 13, 14) and / or the furnace outlet openings have an external conveyor (9, 12) which extends in the longitudinal direction of the furnace. 10) is provided for the products, which is synchronized with the furnace internal lifting beam = conveyor (2, 3) or matched to this. and feeds the products in the same direction and at the same speed of the furnace-internal walking beam conveyor (2, 3), insertion means (16, 20) for introducing the products into the furnace through any one the lateral oven inlet openings (11, 12, 13, 14) and for transferring the products from the oven-external conveyor (9, 10) to the oven-internal walking beam conveyor (2, 3) and / or ejection means for pushing the products out of the oven by any of the Lateral furnace outlet = openings and for transferring the products from the furnace = inner walking beam conveyor to the furnace outer conveyor, as well as control and control means for classifying the products to be heated and / or the products heated in the furnace based on their temperature and / or their Cross-section, in particular its strength, and / or its quality and / or any other parameter, and means for introducing the products to be heated into the furnace based on their arrangement either directly through the first furnace inlet opening (11) or for diverting these products on the outer conveyor (9, 10) and their introduction into the oven with more or less delay due to egg ne of the successive lateral oven inlet openings (12, 13, 14) in alignment with an empty space on the inside of the oven = lifting bar conveyor (2, 3) and / or means for ejecting the heated products from the oven due to their classification either by the last one Furnace outlet opening or with a more or less large advance through one of the upstream, lateral furnace outlet openings on the assigned outer conveyor are provided. 6. Furnace according to claim 5, characterized in that the furnace outer conveyor (9, 10) is arranged only on the furnace inlet side and a plurality of lateral ones in the furnace = longitudinal consecutive furnace inlet openings is assigned. 7. Furnace according to claim 5, characterized in that the furnace outer conveyor is arranged only on the furnace outlet side in the area of a plurality of lateral furnace outlet openings which follow one another in the longitudinal direction of the furnace. 8. Furnace according to claim 5, characterized in that both on the furnace inlet side and on the furnace outlet = outlet side there is an outer, lateral conveyor extending in the longitudinal direction of the furnace in the region of a plurality of consecutive furnace inlet openings or furnace outlet openings . 9. Oven according to one of claims 5 to 8, characterized in that the successive lateral oven = inlet or oven outlet openings are designed to let through one product at a time. 10. Oven according to one of claims 5 to 8, characterized in that the lateral oven inlet or outlet openings have a width which corresponds to at least a partial length of the assigned conveyor outside the oven. 11. Oven according to one of claims 5 to 10, characterized in that the oven outer conveyor from a step conveyor, in particular a walking beam conveyor (9, 10), which is driven synchronously with the inner walking beam conveyor (r, 2, 3) in the same cycle and with the same step size or with such an assignment to the inner walking beam conveyor (2, 3) that one on the outside Walking beam conveyors (9, 10) always occupy a free, moving empty space on the inner stroke = beam conveyor (2, 3). 12. Furnace according to claim 11, characterized in that in the area of each lateral furnace inlet or furnace outlet = opening (12, 13, 14) the fixed beams (2, 9) of the furnace-internal walking beam conveyor (2, 3) and the furnace-outside walking beam = conveyor (9, 10) have transverse guides (22) for the products which are aligned with one another and with the relevant lateral oven inlet or outlet outlet. 13. Oven according to one of claims 5 to 12, characterized in that the outer outer conveyor (9, 10) on the furnace inlet side or on the furnace outlet side in a thermally insulated, in particular with the help of the exhaust gases of the walking beam furnace (1) heatable chamber (17) is accommodated. 14. Oven according to claim 13, characterized in that the heat-insulated and heated chamber (17), in which the outer, lateral furnace inlet conveyor (9, 10) is placed, forms a prechamber of the walking beam furnace (1), the heating curves of which Antechamber (17) and the furnace (1) are different and intersect in the points of convergence of the products.

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