JP6608846B2 - Nozzle apparatus and method for processing flat steel products - Google Patents

Description

  The present invention relates to a nozzle apparatus and method for processing flat steel products.

  Such a nozzle device supplies a gas or gas mixture as close as possible to the flat steel product, so that the gas or gas mixture supplied to the flat steel product is specifically a flat steel product ( In particular, it is provided for treating (eg nitriding or carbonizing) its surface). Flat steel products generally take the form of strips that are transported through a continuous heating furnace for heat treatment purposes. The treatment (e.g. nitriding or carbonizing) preferably allows an increase in the strength of the flat bar product finally leaving the continuous furnace without adversely affecting the expansion capacity of the flat bar product in this step. .

  The improvement in the quality of the flat steel product brought about by the surface treatment here depends critically on the gas feed rate and gas composition through the nozzle device. The decisive factor here reaches the surface of the flat steel product, which is responsible for the ability of the nozzle device to “blast” the flat steel product as uniformly as possible with the gas or gas mixture and the surface treatment (eg nitriding) The ratio of the gas or gas mixture to be produced. The normal situation is that the nozzle device comprises a tube with an outlet opening through which a gas or gas mixture flows out. Feeding to one end of the tube ultimately results in an undesirable flow profile gradient along the outlet opening.

  A successful means for homogenizing the flow profile of a gas or gas mixture in contact with a flat steel product is disclosed in prior art German patent application in the form of an arrangement of openings with different sized openings. This is disclosed in Japanese Patent No. 10210106823. The individual sizes of the openings are here configured to suppress potential pressure drops along the flow direction in the outlet region.

German Patent Application Publication No. 10201105683

  The object of the present invention is to provide a further improvement of existing nozzle devices for the surface treatment of flat steel products. Here, it is particularly desirable to achieve a gas flow or gas mixture flow that is in spatially uniform contact with the flat steel product, thereby improving the quality of the finally produced flat steel product.

  An object of the present invention is a nozzle device for processing flat steel products, the nozzle device comprising an outer tube and an inner tube, the inner tube being disposed within the outer tube, and the inner tube being a nozzle. A primary opening for supplying gas flowing through the device to the outer tube, the outer tube comprising a secondary opening for gas flowing out of the nozzle device in the direction of the flat steel product, the primary opening and the secondary opening; Is achieved by means of a nozzle arrangement that is offset from one another along the direction of gas flow.

  In contrast to the prior art, the staggered arrangement of the primary openings relative to the secondary openings allows the flat steel products to flow out of the secondary openings in a spatially uniform manner and “blast” the flat steel product as uniformly as possible, preferably over its entire width. Realize gas flow. The fact that the selected geometry results in the gas or gas mixture flowing uniformly over its residence time in the nozzle device is particularly exploited here. Otherwise (unless it is a design with an inner tube and an outer tube), an undesirably graded flow rate profile is formed along the outlet opening due to the gas being supplied to one end of the nozzle device Is done. In addition, the outflow behavior of the prior art nozzle device is influenced by different temperatures of the gas or gas mixture, whereby different flow rates are generated along the outlet opening. The nozzle device according to the invention, in contrast, achieves a uniform flow profile along the secondary opening that serves as the outlet opening.

  The direction of gas flow is here determined essentially by the outer circumference of the inner or outer tube. Specifically, the outer tube or outer circumference of the inner tube is determined by a cross-sectional plane extending perpendicular to the longitudinal direction, the longitudinal direction being essentially defined by the overall progression of the inner and outer tubes. Is done. Specifically, the flow direction (essentially up to the primary opening) of the gas or gas mixture flowing through the nozzle device extends parallel to the longitudinal direction and is then redirected, for example by about 90 °. The primary and secondary openings are preferably outlet faces through which the outlet face is guided as gas or gas mixture is supplied from the inner tube to the outer tube and out of the outer tube. Have. The exit face of the inner tube is preferably smaller than the outer tube. It is also realized that the outlet face of the inner tube has a circular configuration and the outlet opening of the outer tube has a slit-like configuration. In particular, the outer tube has a slit having a slit width of less than 8 mm, preferably less than 6 mm, particularly preferably less than 4 mm.

  Preferred configurations and developments of the invention can be seen from the dependent claims and the description with reference to the drawings.

  In a further embodiment, it is realized that the primary opening and the secondary nozzle opening are displaced from each other essentially by 90 ° to 180 ° along the direction of gas flow. This geometry configuration makes it possible to achieve a particularly uniform profile of the gas flow rate exiting through the secondary opening.

  In a further embodiment, it is realized that the primary opening and / or the secondary opening comprise a gas guidance system for directing the gas flow direction. The gas guidance system is preferably part of the secondary opening and has an eaves-like configuration and includes an extension that forms an exit slit that converges in the direction of gas flow. This means that the gas flow can be directed or concentrated specifically in the region of the band.

  In a further embodiment, it is realized that the nozzle device comprises a plurality of primary openings and / or a plurality of secondary openings. The nozzle device is preferably a plurality of primary openings which are arranged on opposite sides of the inner tube and are each offset by 90 °, for example, with respect to the secondary openings when viewed in the direction of flow. A plurality of primary openings. It is a preferred situation that the primary openings (in a region extending parallel to the secondary openings) are regularly arranged, preferably equally spaced. Specifically, the primary opening is located at an appropriate position with respect to the secondary opening. For example, the primary openings are distributed symmetrically with respect to the first center point of the inner tube, the first center point being the same as the second center point of the secondary opening and perpendicular to the longitudinal extent of the tube. Arranged in an extending plane. Preferably there are more primary openings than secondary openings. In particular, there are always primary openings, preferably four primary openings, which are always arranged in pairs along the longitudinal extent of the inner tube and opposite one another (in which case they are In each case, it is shifted by, for example, 90 ° with respect to the secondary opening when viewed in the direction of distribution). A design that collects the various primary apertures within the region determined by the secondary apertures may preferably further improve the flow velocity profile along the secondary apertures.

  In a further embodiment, it is realized that the primary opening is arranged in the region of the secondary opening and / or the inner and outer tubes are arranged coaxially. In this way, it can be ensured that preferably all possible proportions of the gas or gas mixture comprise the same path in the nozzle arrangement. This ultimately has a positive effect on the flow velocity profile along the secondary aperture.

  In a further embodiment, it is realized that the secondary opening is directed to a band comprising a flat steel product and the secondary opening is spaced from the band by less than 25 cm, preferably less than 15 cm, particularly preferably less than 10 cm. Specifically, the strip passes through the nozzle device along the direction of travel and the secondary opening (preferably with its gas guidance system) extends the gas or gas mixture flowing out essentially perpendicular to the strip. Arranged to have a flow direction. The reduction in distance preferably allows an increase in the proportion of gas that reaches the surface of the flat steel product, thereby ensuring the desired surface treatment (eg nitriding or carbonizing). The greater this ratio, for example with respect to nitriding or carbonizing, the higher the strength. At this time, the expansion capacity of the flat steel product to be produced is not significantly impaired. Specifically, as a result of this, it is possible to reduce the thickness of flat steel products without the risk of loss of strength. Therefore, it is finally possible to reduce the amount of material used for the production of products produced from flat steel products.

  In a further embodiment, it is realized that the secondary opening extends essentially across the width of the band, the width of the band extending essentially perpendicular to the direction of travel of the band. A spatially uniform flow profile makes it possible to ensure that the flat steel product produced is surface treated as uniformly as possible along its width. This preferably avoids situations where there is a variation in strength along the width of the produced flat bar product.

  In a further preferred embodiment, it is realized that the gas flowing through the nozzle device comprises ammonia and possibly nitrogen and / or inert gas. The use of nitrogen and / or inert gas preferably increases the pulse of gas so that it can penetrate the boundary layer entrained by the strip, and between ammonia and the strip (ie, flat steel product). Direct reaction is possible.

  In a further embodiment, it is realized that the nozzle device comprises a fixed mixer for mixing ammonia, nitrogen and / or inert gas, and the piping system directs the gas towards the front inner tube. The This makes it possible to achieve a uniform gas mixture over the entire width of the secondary opening in a straightforward and uncomplicated manner.

  In a further embodiment, the piping system supplies gas to the additional inner tube, the additional inner tube comprises an additional primary opening for directing gas to the additional outer tube, and the additional outer tube adds It is realized that the inner tube is at least partly accommodated and the outer tube is provided with an additional secondary opening for gas flowing out of the nozzle device in the direction of the flat steel product. Here, it is conceivable that the band is conveyed, for example through a turning roller, so that the additional secondary openings are arranged at different positions in the path of the band.

  In a further embodiment, the gas exiting through the secondary opening nitrides the first side of the flat steel product and the gas exiting from the additional secondary opening nitrides the second side of the flat steel product. Is realized. Thus, the flat steel product may preferably be surface treated on both sides.

  In a further embodiment, the nozzle device comprises a supply pipe system for supplying ammonia, nitrogen and / or inert gas to a fixed mixer, the supply pipe system comprising individual gases and / or ammonia, nitrogen, It is realized to comprise respective means for measuring and / or controlling the volumetric flow rate of the gas mixture composed of and / or inert gas. With the aid of measuring and control means, it is possible preferably to control the amount and / or composition of the gas or gas mixture and to adapt it to the optimum requirements for successful nitridation.

  In a further embodiment, it is realized that the nozzle device is arranged in a continuous furnace for the heat treatment of steel products.

  The invention further relates to a method for the surface treatment of a steel strip in a continuous furnace for heat treatment of steel products, the furnace comprising a nozzle device according to the invention. Such a nozzle device makes it possible to realize a flat steel product that is subjected to a surface treatment more effective than that known from the prior art.

  In a further embodiment of the invention, in the first step, gas is supplied to the inner tube, in the second step, the gas is directed through the primary opening to the outer tube, and in the third step, the gas However, a process for nitriding a flat steel product by flowing out of the outer tube of the nozzle device through the secondary opening is realized. In this way, it is possible, preferably, to provide a method that allows the production of thinner flat steel products, for example the effect of nitriding or carbonizing and the resulting strength improvement. The resulting reduction in the amount of material used preferably results in significant production cost savings in the mass production of products from flat steel products.

  Further details, features and advantages of the present invention can be obtained from the following description of preferred embodiments with reference to the drawings and drawings. The drawings here only show exemplary embodiments of the invention, which do not limit the inventive concept.

1 shows a nozzle device according to a first exemplary embodiment of the present invention. FIG. 6 shows a perspective view of a nozzle device according to a second exemplary embodiment of the present invention. Figure 2 shows two different plan views of a nozzle device according to a second exemplary embodiment of the present invention. FIG. 4 shows a cross-sectional view of a nozzle device according to a second exemplary embodiment of the present invention.

  The same parts are always given the same reference signs in the various figures, and thus, in general, each of the same parts is also referenced or referred to only once.

  FIG. 1 shows a nozzle device 10 for the treatment or surface treatment of flat steel products 3 according to a first exemplary embodiment of the invention. Such a nozzle device 10 is preferably a continuous heating furnace through which a flat steel product is transported in the form of a strip 33, i.e. in the form of a steel strip. Part. In a continuous furnace, for the purpose of material improvement, the flat steel product is subjected to a heat treatment wherein a gas or gas mixture is supplied to the flat steel product (eg for nitriding purposes). For example, at least the recrystallization temperature of the flat steel product is distributed in the continuous heating furnace. For example, nitriding or carbonizing makes it possible to increase the strength of a flat steel product without appreciably affecting its expansion capacity. If the strength-related requirements to be met by the finished product remain the same, a thinner flat steel product 3 can be realized. At this time, the resulting reduction in the amount of material used can result in significant cost savings.

  A decisive factor in improving quality by surface treatment (eg nitriding or carbonizing) is the way in which gas is supplied to the flat steel product 33, the gas supply being essentially determined by the nozzle device 10. It is a method. With respect to the nozzle device 10, it is here realized that the gas guided through the nozzle device 10 for the purpose of surface treatment (eg nitriding) is first supplied to the inner tube 1 of the nozzle device 10. The gas exits the inner tube 1 through the primary opening 11 of the inner tube 1 and is supplied to the outer tube 2 that at least partially houses the inner tube 1. From there, the gas then leaves the nozzle device 10 via the secondary opening 12. The primary opening 11 and the secondary opening 12 are here offset relative to each other along the direction of flow (essentially determined by the outer circumference (extending along the cross section) of the inner tube 1 and the outer tube 2). Specifically, the primary opening 11 is shifted with respect to the secondary opening 12 by, for example, 90 °. Preferably, here it is realized that the primary opening 11 and the secondary opening 12 are arranged in the connection region of the nozzle device 10. In detail, the secondary opening 12 is arranged in the part of the outer tube 2 that at least partially accommodates the primary opening 11. Here, it is also realized that the secondary opening 12 is directed to the band 33 (ie a flat steel product). The mutual arrangement of the primary opening 11 and the secondary opening 12 is preferably asymmetric from the secondary opening 12 (which serves as the outlet opening) (as would be expected in the absence of the inner tube 1). And the gas has different temperatures along the secondary opening 12 and across the width of the strip 33, eventually preventing the situation where the exit velocity from the secondary opening 12 is different. Instead, the nozzle device 10 having the primary opening 11 of the inner tube 1 and the secondary opening 12 of the outer tube 2 is uniform (ie, uniform and uniform) gas across the width of the secondary opening 12 and the band 33. It is possible to realize the exit behavior of In this way, the gas supply from the nozzle device 10 to the flat steel product 3 is improved. It is also realized that the width of the secondary opening 12 is at least as large as the band 33. The secondary opening 12 is here directed to the strip such that its longest surface extends essentially perpendicular to the transport direction of the strip 33.

Here, it is also realized that the secondary opening 12 comprises a gas guidance system 5. The gas induction system 5 serves here to direct the gas or gas mixture flowing out of the secondary opening 12 and thereby to apply the gas flowing out of the nozzle device 10 to the flat steel product in a specific way. The gas guidance system 5 preferably has two regions of the outer tube 2 that extend towards each other to form a bowl-shaped opening. The slits between the two regions of the outer tube, which extend towards each other, here form the secondary opening 12. In addition to the inner tube 1 and outer tube 2, essentially the same, additional 'extra inner tube 1 having a' primary opening 11, and, similarly of essentially identical, the additional secondary opening 12 ' An additional outer tube 2 'having is also realized. With the help of this second arrangement consisting of an additional secondary opening 12 ′ and an additional primary opening 11 ′, preferably the first of the flat steel product, for example, by gas flowing out of the secondary opening 12. Nitriding the second surface of the flat steel product with gas exiting through the additional secondary opening 12 ', so that both surfaces of the flat steel product are preferably For example, it can be nitrided. In such a nitriding on both sides, the flat steel product is preferably guided through the turning roller 31, in which case the additional secondary opening 12 ′ and the secondary opening 12 are used to transport the flat steel product. Spatial separation along the direction.

  Here, it is also realized that gas is supplied to the inner tube 1 and / or the additional inner tube 1 ′ from the static mixer 18 via the tube system 14. Ammonia for nitriding flat steel products is preferably mixed in a static mixer 18 with a gas mixture made from nitrogen and / or inert gas. The addition of nitrogen and inert gas improves nitriding by ensuring a larger pulse of gas that can eventually penetrate the boundary layer entrained by the band surface. This allows the realization of an immediate reaction between the flat bar product and ammonia, which ultimately results in a more effective nitriding and thus further improves the quality of the nitrided flat bar product.

  Here, it is also realized that ammonia, nitrogen and / or inert gas is supplied to the static mixer 18 via the supply pipe system 13. The inert gas preferably comprises a hydrogen / nitrogen mixture. With particular reference to the controlled gas supply, it is here realized that the through-flow is monitored by means 17 for measuring the volume flow or by a flow meter. Specifically, the nozzle device 10 also comprises means for controlling the volume flow rate and amount of each gas supplied to the static mixer. For example, such a means is a valve 16 incorporated in the supply pipe system 13. In this way, the material composition in the secondary opening 12 or the additional secondary opening 12 ′ can be adapted to the desired composition or measurement for the respective nitriding step, preferably in a straightforward and direct manner. It is. Here, it is realized that the nozzle device 10 obtains gas from the first reservoir 21 (for example, for ammonia) and the second reservoir 22 (for example, for nitrogen). In order to ensure the same volumetric flow through both illustrated nozzle devices, the conduits are placed identically / symmetrically downstream of the static mixer. Thus, the pressure loss in the two branches is the same, thereby achieving the same pulse for both sides of the band. As an alternative, it is also possible to attach a regulating device (not shown) to achieve the same pulse.

  FIG. 2 shows a perspective view of a nozzle device 10 according to a second exemplary embodiment of the present invention. What can be seen in the left part of the figure is essentially the outer tube 2, while on the right side, the outer tube 2 allows the inner tube 1 to be seen within the outer tube 2 in the figure. Shown in perspective. Preferably, it is realized that the inner tube 1 and the outer tube 2 are arranged coaxially. However, in alternative embodiments it is also conceivable that the inner tube 1 is offset from the central axis B in the outer tube 2. For example, the inner tube 1 may be disposed in a region located on the opposite side of the secondary opening 12 in the outer tube 2. It is also realized that an inner tube 1 with a primary opening 11 and an outer tube 2 with a secondary opening 12 are arranged at the end of a tube system 14 (one of which is fed with a gas or gas mixture). Is done. The gas here is, for example, via four primary openings (and preferably symmetrically arranged primary openings (not shown)) arranged in pairs in opposite regions of the inner tube 1. Go out of the inner tube 1. The pair of primary openings 11 is here shifted by, for example, 90 ° with respect to the secondary openings 12 when viewed in the direction of flow in any case. It is also realized that the sum of the outlet faces of the primary opening 11 (or its outlet face as a whole) is smaller than the outlet face of the secondary opening 12. The exit face is to be understood as the face where gas is supplied from the inner tube 1 through the outer tube 2 or the face where the gas exits through the nozzle device 10. It is also realized that the flow direction of the gas or gas mixture is directed to the flat steel product in a specific way with the aid of the gas induction system 5. For this purpose, the gas guiding system 5 preferably has two extensions 23 of the outer tube 2, the distance between the extensions being the flow direction A of the gas flowing out of the secondary opening 2. It becomes gradually smaller along the direction extending in parallel. Here, the extending part 23 can be linear or curved.

  FIG. 3 shows two different plan views of the nozzle device 10 according to the second exemplary embodiment of the present invention. In the plan view, the upper part of the figure shows the exit face of the primary opening 11, and the lower part of the figure shows the secondary opening 12. The plurality of primary openings 11 (or one primary opening 11) is preferably placed in the middle of the secondary openings (when viewed in the longitudinal direction determined by the outer and inner tubes). The projection of the center point of the secondary opening 12 here (when viewed in a direction extending perpendicular to the longitudinal direction) is essentially the region and nature of the inner tube 12 that is arranged in the center between the two primary openings 11. Match. It is also realized that the distance between the two primary openings 11 along the longitudinal direction is smaller than the range of the secondary openings 12 along the longitudinal direction. Specifically, the gas guidance system 5 extends over the entire range of the secondary opening 12. It is also realized that the flow direction of the gas or gas mixture is essentially redirected, for example by 90 ° as a result of the arrangement of the primary opening 11 and the secondary opening 12.

  FIG. 4 shows a cross section of a nozzle device 10 according to a second exemplary embodiment of the present invention. Here, it is realized that the secondary opening 12 is arranged between two virtual planes 24 each including at least one primary opening 11. The secondary opening 12 is preferably arranged in the middle between these two virtual planes. It is also realized that the slit width 25 of the secondary opening 12 is determined by the extension 23 of the gas guidance system 5 extending towards each other. The slit width 25 is preferably smaller than the range of the inner tube 1 along the direction extending perpendicular to the longitudinal direction. In detail, the slit width 25 is smaller than 8 mm, preferably smaller than 6 mm, particularly preferably smaller than 4 mm. It is also realized that the extension 23 of the gas guiding system 5 is preferably produced at least partly from the same material as the outer tube 2. For example, its cross-section (along a direction extending perpendicular to the longitudinal direction) in which the inner tube 1 occupies less than 45%, preferably less than 40%, particularly preferably less than 35% of the installation space defined by the outer tube 2 It is realized to have For example, it is realized that the inner diameter of the outer tube 2 is less than 300 mm, preferably less than 280 mm, particularly preferably less than 260 mm and that the inner diameter of the inner tube 1 is less than 100 mm, preferably less than 90 mm.

DESCRIPTION OF SYMBOLS 1 Inner tube 1 'Additional inner tube 2 Outer tube 2' Additional outer tube 3 Flat steel product 5 Gas guidance system 10 Nozzle apparatus 11 Primary opening 11 'Additional primary opening 12 Secondary opening 12' Additional secondary opening 13 Supply pipe system 14 Piping system 16 Valve 17 Means 18 for measuring volumetric flow rate Fixed mixer 21 First reservoir 22 Second reservoir 23 Extension 24 Virtual plane 25 Slit width 31 Direction change roller 33 Band / flat Steel product A Flow direction B Center axis

Claims (13)

A method of nitriding the flat steel product (3) in a continuous heating furnace for heat treatment of the flat steel product (3) ,
The continuous furnace has a nozzle device (10),
The nozzle device (10) comprises an outer tube (2) and an inner tube (1),
The inner tube (1) is disposed inside the outer tube (2);
The inner tube (1) comprises a primary opening (11) for supplying gas flowing through the nozzle device (10) to the outer tube (2);
The outer tube (2) comprises a secondary opening (12) for the gas flowing out of the nozzle device (10) in the direction of the flat steel product (3);
The primary opening (11) and the secondary opening (12) are displaced from each other along the gas flow direction;
The nozzle device (10) comprises an additional outer tube (2 ′) and an additional inner tube (1 ′),
The additional inner tube (1 ′) is disposed within the additional outer tube (2 ′);
The additional inner tube (1 ′) comprises an additional primary opening (11 ′) for supplying the gas flowing through the nozzle arrangement (10) to the additional outer tube (2 ′);
The additional outer tube (2 ') comprises an additional secondary opening (12') for the gas flowing out of the nozzle device (10) in the direction of the flat steel product (3);
It said additional primary opening (11 ') and said additional secondary opening (12') is, along the direction of flow of the gas are offset from one another, the method. The method according to claim 1, wherein the primary opening (11) and the secondary opening (12) are essentially offset from each other by 90 to 180 along the direction of gas flow. The said primary opening (11) and / or the said secondary opening (12) are equipped with the gas guidance system (5) for directing the flow direction (5) of the said gas, The claim 1 or 2 Way . The method according to any of the preceding claims, comprising a plurality of primary openings (11) and / or a plurality of secondary openings (12). The primary opening (11) is arranged in the region of the secondary opening (12) and / or
The method according to any of the preceding claims, wherein the inner tube (1) and the outer tube (2) are arranged coaxially. Said secondary opening (12) is directed to a band (33) comprising said flat steel product (3), said secondary opening (12) being less than 25 cm, preferably less than 15 cm, particularly preferably less than 10 cm The method according to any of the preceding claims, wherein the method is spaced from the band (33). The secondary opening (12) extends essentially across the width of the band (33), and the width of the band (33) is essentially perpendicular to the direction of travel of the band (33). The method of claim 6, extending along. The gas flowing through the nozzle device (10) comprises nitrogen and / or inert gas if ammonia and possibly A method according to any of claims 1 to 7. The nozzle device (10) comprises a fixed mixer (18) for mixing ammonia, nitrogen and / or inert gas, and a piping system (14) is connected to the front inner tube (1) and the The method according to any of the preceding claims, wherein the gas is directed towards an additional inner tube (1 '). The method according to claim 9, wherein the piping system (14) comprises a plurality of conduits arranged identically or symmetrically downstream of the fixed mixer. The gas exiting through the secondary opening (12) nitrides the first surface of the flat steel product (3), and the gas flowing out of the additional secondary opening (12 ′) 11. A method according to any one of the preceding claims, wherein the second surface of the steel product (3) is nitrided. The nozzle device (10) comprises a supply pipe system (13) for supplying ammonia, nitrogen and / or inert gas to the fixed mixer (18),
The supply pipe system (13)
Said individual gases and / or
Method according to claim 9, comprising respective means (16, 17) for measuring and / or controlling the volumetric flow rate of a gas mixture composed of ammonia, nitrogen and / or the inert gas. The nozzle device (10) comprises flat is placed in a continuous furnace for heat treatment of steel products (3) A method according to any one of claims 1 to 12.

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