KR20140048330A - Plant for coating flat metal products by means of continuous hot dipping and relative coating process - Google Patents

Abstract

The plant coating the strips 5 by continuous hot dip plating includes a storage tank 2 for containing molten zinc; A coating vessel 3 adapted to receive and contain molten zinc, disposed above the storage tank and provided with an opening 4 at the bottom for passing the strip to be coated; A chamber 6 disposed below the coating vessel, provided with guide rollers 7, 8 for guiding the strip towards the opening, wherein the storage tank is under the guide roller and inside the chamber. Disposed in the chamber and the storage tank form a single position, and an intercepting and conveying system 9 disposed between the coating vessel and the storage tank is provided in the chamber, whereby molten zinc leaks out of the opening. Intercept and transfer to the storage tank, the intercept and transfer system is configured to bypass and wind the strip fed towards the guide roller and the opening.

Description

Plant for coating flat metal products by means of continuous hot dipping and relative coating process

The present invention relates to a plant for coating a flat metal product, such as a steel strip, by means of continuous hot dip coating with a coating metal, which may be for example zinc or an alloy comprising zinc, and a flat metal product To a related coating process by continuous hot dip plating.

Known processes for coating steel strips provide for vertically passing the strip through a molten metal bath that is kept semi-levitation by alternating magnetic fields.

Conventional hot dip galvanizing methods are continuous, usually as a preliminary step, requiring pretreatment, and preheating of the steel strip with careful control of the temperature of the strip before applying the coating. The pretreatment—chemical and thermal—improves adhesion of the coating on the strip, and the preheating step is a preheating operation in a controlled atmosphere to coat the surface of the strip with a protective film to prevent oxidation of the strip. And flow operation of impregnating the strip with reduced inorganic flux.

When the steel strip is to be preheated in a controlled atmosphere, the steel strip can enter the coating bath at high temperatures, and in the case of a bath made of zinc or zinc alloy, this temperature can also be equal to the temperature of the metal bath.

This kind of hot galvanizing method provides a coating step carried out in a semi-injured bath in a container with an opening at the bottom that allows the strip to pass upwards. The strip is guided by one or two deflector rollers disposed below the melt coating bath. The strip usually enters the jaw from below in a substantially vertical direction and then passes through the molten coating material. The strip is then extracted from the metal bath in the vertical direction.

Known systems that utilize the magnetic flotation of a bath disadvantageously involve disturbances in the lower meniscus of the bath and thus inevitable leakage of the coating liquid through the opening in the bottom of the vessel containing the bath. The probability of melt leakage through the lower menisker increases the oscillation of the strip. Furthermore, leakage of the melt is always present at the starting or stopping stage of the plant and in any emergency that requires stopping the plant.

Disadvantageously, the coating liquid leaking from the vessel containing the bath falls onto the underlying strip, which is in a stationary or transported state towards the container and on the guide roller of the strip itself. The adhesion of the droplets of the coating liquid on both the strip and the guide roller causes imprint formation on the strip, which degrades the quality of the final product.

Furthermore, droplets of coating liquid adhering to the guide rollers require frequent downtime of the plant to clean the dirty rollers for replacement and subsequent reuse.

Known coating plants are disclosed in document US6290776B1. The plant is a sophisticated seal that delivers the leaked molten metal into at least one collection tank provided on the top of the guide roller, in order to limit the melt falling from the opening of the funnel towards the guide roller of the strip, only at the plant starting and stopping phase. Provide a system. There are special means of movement provided for moving the sealing system, for example hydraulic pressure (example 5). This solution, in addition to being complicated and expensive, does not allow the transfer of leaks of liquid metal which is always present even during steady state operation of the plant.

Further known plants are disclosed in document US5702528A. The plant stops application of the magnetic field and is activated only in an emergency situation where the molten metal is discharged from the funnel and provides a conveying means for conveying the molten metal from the opening of the funnel.

Accordingly, there was a need to provide a plant and a coating method associated therewith that coat a flat metal product by continuous hot dip plating to overcome the aforementioned disadvantages.

The main object of the present invention is to provide a plant for coating a flat metal product, for example a steel strip, by continuous hot-dip plating of a container containing a hot dip coating bath disposed on a guide roller of a strip, the plant being simple and costly. It has an efficient structure and is configured for optimized management of coating liquid leakage at the bottom of the vessel during operation at both the starting or stopping stages of the plant, or in any emergency situation in which the plant should be stopped, and during normal operation of the plant. .

It is another object of the present invention to provide a plant which increases the productivity of the plant by improving the surface quality of the final product, reducing maintenance work and increasing the speed of the strip to be coated.

Another object of the present invention is to provide a related coating process by continuous hot dip plating of flat metal products, which has better efficiency than known methods.

Accordingly, the present invention provides a plant for coating a flat metal product by continuous hot dip plating to achieve the above object, comprising: a storage tank for containing a molten coating material according to claim 1; A coating container adapted to receive and contain a molten coating material, disposed above the storage tank, and provided with an opening at the bottom to pass a flat metal product to be coated; A chamber disposed below the coating vessel and provided with a guide roller for guiding the flat metal product towards the opening, wherein the storage tank is disposed below the guide roller and inside the chamber such that the chamber and the storage tank are in a single position. And an intercepting and conveying system disposed between the coating vessel and the storage tank in the chamber, the intercepting and conveying system being configured to intercept and convey the molten coating material leaking from the opening to the storage tank. The system has a structure defining a cavity opposite the storage tank; The cavity at least partially receives at least one first guide roller that is adapted to turn as the flat metal product enters the chamber, the cavity forwards the flat metal product disposed above the first guide roller and fed toward the opening. Fully receive at least one second guide roller adapted to stabilize, the flat metal product supplied towards the guide roller and the opening is fully protected from droplets of molten coating material during steady state operation of the plant, or starting or stopping steps It is proposed to provide a plant that is fully protected from falling of large amounts of molten coating material in both and maintenance or emergency steps.

A second aspect of the invention provides a method of coating a flat metal product by continuous hot dip plating, and according to claim 14, comprising the following steps:

Providing the single location with an inert atmosphere that is higher than the pressure outside of the location;

Feeding the flat metal product into the chamber by the guide roller towards the coating vessel,

Coating a flat metal product inside the coating vessel;

In the process, the molten coating material leaking out of the opening of the bottom of the coating vessel is intercepted and transported into the storage tank by the intercept and transfer system provided in the chamber, thereby protecting the guide rollers and the structure of the intercept and transfer system. It protects the flat metal product that is fed toward the opening in the cavity of the chamber.

Preferably, the intercept and transfer system for the coating liquid leaking out of the coating vessel is configured to protect both the strip and the guide rollers fed towards the vessel, and transfer the coating liquid to the storage tank for direct recovery. May be matched to the melting tank for the ingot of the coating material in a preferred embodiment. The recovered coating liquid is pumped from the storage tank to be taken back into a coating vessel, also known as a funnel.

The intercept and transfer system, or the containment and transfer system, define channels that diverge from one another in the direction from the coating vessel to the storage vessel. In this way, it is possible to recover the coating liquid without soiling the strip and the guide rollers so that no imprint occurs on the strip, thereby improving the surface quality of the strip. In addition, the work of having to clean the guide roller and the wall of the chamber is no longer necessary.

In a preferred embodiment, two deflectors are provided in the intercept and transfer system, the purpose of which is located beneath the droplets of molten metal leaking from the bottom of the electromagnetic device in which the inductor and the molten metal bath are received and comprising the coating bath. In order to protect the strip and guide roller, the turning roller and the stabilizing roller. By the shape of this deflector the droplets flow accordingly and are led into a storage tank, also known as a zinc pot. The two deflectors define the spacing through which the strip passes, which is close to the passage area between the chamber or thermal machine and the electromagnetic device or magnetic machine.

In particular, the branch channel is, by means of a pair of deflectors having an upper end defining the spacing for passing the strip in the vertical direction, parallel or non-parallel with respect to each other, and outside and independent of the deflector. Defined by a structure.

Preferably, a kinematic mechanism is provided to adjust the spacing between the deflectors, which may also perform an immediate closure in case of an emergency.

The chamber, actively heated by appropriate heating means, connects the storage tank to an electromagnetic flotation device or a simple electromagnetic device (electromagnetic galvanizer if the coating is zinc-based), which increases the density of the entire plant. It is configured to.

The temperature at the single location defined by the chamber and the storage tank is preferably the holding temperature of the zinc-based coating material in the molten state, for the optimized condition of the strip, ie the process of adhering zinc to the strip is better. Is maintained continuously at about 450-490 ° C. In this way, all the members in the single position, i.e. the inner wall and the fixed and / or movable member, will be kept at this temperature.

Preferably, the atmosphere at the single location is an atmosphere of nitrogen introduced at a pressure greater than the external atmospheric pressure to prevent the presence of an inert gas such as oxygen to reduce the formation of DROSS.

Another advantage is that the bearings of the guide rollers are outside of the chamber, thus preventing them from being subjected to the high temperatures of the chamber locations, and allowing for possible maintenance and / or replacement work without undue loss of time.

The dependent claims describe preferred embodiments of the invention.

Other features and advantages of the present invention will become more apparent from the following detailed description of the preferred, but not exclusive, embodiments of a plant for coating flat metal articles by continuous hot dip plating, and the accompanying drawings of the non-limiting examples. It is shown with reference to. here :
1 is a first side cross-sectional view of one embodiment of a plant of the present invention;
1A is a partially enlarged view of the first side cross-sectional view of FIG. 1;
2 is a second side cross sectional view of the embodiment of the plant of FIG. 1;
3 is a side view of a first part of the plant of FIG. 1;
4 is a perspective view of said first part of the plant;
FIG. 5 is a cross-sectional view taken along plane HH and plane BB shown in FIG. 3;
6 is a plan view of a second part of the plant of the invention;
FIG. 7 is a sectional view along plane AA of the second part of the plant of FIG. 6;
8 is a perspective view of said second part of the plant of the invention;
9 is a plan view of said first and second parts of the plant of the invention.
Reference numerals in the drawings identify the same members or components.

With reference to the drawings a preferred embodiment of a plant for coating a flat metal product by continuous hot dip plating is shown, which is indicated by reference numeral 1 throughout the specification. In the course of the present description mention is made by way of example of a galvanizing plant for metal strips, for example steel, the coating material being zinc-based, for example molten zinc or molten zinc alloy and the electromagnetic device is an electromagnetic zinc plating machine. However, the plant of the present invention can also be used for continuous coating of metal strips with other metal materials, for example aluminum based, alloys of aluminum, magnesium, silicon, tin, lead and alloys thereof.

The plant 1 is:

A storage tank 2 for containing molten zinc;

A coating container (3) adapted to receive and contain molten zinc, disposed above the storage tank (2) and provided with an opening (4) at the bottom for passing the strip (5);

A chamber 6 disposed below the coating vessel 3 and provided with guide rollers 7, 8 for guiding the strip 5 towards the opening 4.

The storage tank 2 is preferably arranged under the guide rollers 7, 8 and inside the chamber 6 such that the chamber 6 and the storage tank 2 form a single position and are coated in the chamber 6. An intercepting and conveying system 9 further provided between the container 3 and the storage tank 2 is further provided to intercept the molten zinc coming from the opening 4 of the coating container 3 and to the storage tank 2. It is configured to be transported to.

The intercept and transfer system 9 is preferably configured to bypass and wind the strip 5 fed towards the guide rollers 7, 8 and the opening 4 from the droplets of molten zinc during steady state operation of the plant. (B) to ensure that a large amount of molten zinc is protected from falling, both during the start or stop phase and during the maintenance or emergency phase.

In particular, the intercept and transfer system 9 has a structure configured to define a cavity, the inlet of the cavity having a structure defining a cavity facing downwards, ie towards the storage tank 2. The cavity interior partially receives at least one guide roller 7 adapted to be turned forward as the strip 5 enters the chamber 6. The cavity furthermore completely receives at least one guide roller 8 arranged above the guide roller 7 and adapted to deflect and stabilize the strip fed towards the opening 4. With this configuration, the strips 5 fed to the guide rollers 7 and 8 and the openings 4 are completely protected from the leakage of molten zinc under any operating conditions.

In a preferred variant the intercept and transfer system 9 is:

A pair of deflectors 12 which protect the strip 5 and the guide rollers 7, 8, each deflector 12 being arranged on either side of the vertical feed plane X of the strip 5 and in the chamber A deflector (FIGS. 5 and 9) connected to two opposing sidewalls 6 'of 6 by a support shaft 17 integral with deflector 12 and thereby flanged to wall 6'. );

And outside the deflector 12 and integrally fixed to the two opposing side walls 6 'of the chamber 6 (FIGS. 1A, 9) to provide a channel for intercepting and transporting towards the storage tank 2 And a structure 20 defining together with the deflector 12.

The deflector 12 preferably has at least the top 13 arranged symmetrically with respect to the vertical feed plane X.

This upper end 13 of the deflector 12 defines the spacing for passing the strip 5 in the vertical direction. This spacing is at least equal to zero when the deflectors lean on each other in the absence of the strip, plus a value between 0.5 and 5 mm for each side of the plane X to the thickness of the strip to be coated during steady state operation. Values can vary.

Preferably, the upper end 13 made of steel of the deflector may be coated with a ceramic material, for example added or obtained in the form of ceramic wear plates or Inconel steel, Sliding can reduce the risk of scratching the strip.

In addition to protecting the strip and the guide rollers, the deflector 12 also functions to stabilize the strip. The magnetic field of the zinc plating machine 10 may in fact be subjected to vibrations, which also cause vibrations and vibrations in the strip with a decrease in current. The passage between the upper end 13 of the deflector 12 may function as a mechanical striker and may reduce the degree of vibration caused during transport of the strip. Therefore, there is an effect of stabilization of the upstream strip of the electromagnetic galvanizing machine 10, which further optimizes the galvanizing process. In practice, stabilization in known plants is provided only downstream of the zinc plating machine.

As better shown in FIG. 3, the deflector 12 has a lower end 14 that is substantially parallel to each other and further spaced from one another with respect to the upper end 13. In practice, a central portion 15 of the deflector 12 is provided, which is substantially flat and has a predetermined angle greater than zero with respect to the vertical supply plane X of the strip 5, preferably between 35 and 45 degrees. More preferably inclined between 40 and 43 degrees. The central portion 15 of the deflector 12 connects the upper end 13 with the lower end 14 to define the cavity described above, so that the turning roller 7 and the stabilizing roller 8 located below All are covered by a pair of deflectors 12. The lower end 14 is positioned to at least partially cover the turning roller 7 having a larger diameter than the stabilizing roller 8 and disposed below it.

Preferably, adjusting means are provided for adjusting the spacing of the deflector, which is configured to adjust the value of the spacing according to the thickness of the strip to be coated and the shaking of the strip.

Control means for adjusting the spacing of the deflector include a kinematic mechanism, which in the case of an emergency makes it possible to adjust the spacing until an immediate closure of the deflector is reached.

Such kinematic mechanisms include, for example, manual or automatic linkages systems 16 guided by threaded bushings 18, which are very precise, even micrometers of spacing. Allow for level adjustments. By actuating the link, two support shafts 17 parallel to the vertical feed plane X are synchronized with respect to the feed plane X of the strip 5 and rotate in a reflective manner. Each support shaft 17 is fixed integrally to each deflector 10, for example by means of a fixing flange 52, preferably close to the lower part of the central part 15, ie the lower part 14. do. Each shaft 17 is inserted into a guide flange 50 fixed to a block 51 connected to the wall 6 ′ at the end (FIG. 5).

In a preferred variant, the link system 16 comprises a series of cams 19 connected by threaded bushings 18 having a very small pitch, for example about 1 mm, which actuates the deflector 12. Allow the lever arm to reach the effective opening. The link system 16 is preferably configured such that the synchronization and reflection rotation about the axis of the support shaft 17 determines the spacing between the upper ends 13 of the deflectors, the spacing of the strips 5 being described above. It is reflective to the supply plane X. This means that in this configuration the upper end 13 of the deflector 12 is parallel when the gap is zero, but at the same time actuating the link system 16 the upper ends 13 are far from each other and no longer parallel to each other. That is, it means that it will form a non-zero angle with respect to the supply plane (X) of the strip.

In a second variant (not shown), there may be two distinct link systems providing adjustment of the spacing by two deflectors that are disconnected and no longer move in a synchronized manner.

In a third variant, the link system can be replaced by, for example, an eccentric system so that the deflector is not made to rotate but rather to be transported independently or simultaneously, so that it always maintains a constant tilt with respect to the axis X. The upper end 13 of the deflector 12 thus remains parallel to each other with respect to the vertical feed plane X of the strip.

In another variant, it provides a deflector that is capable of both rotation and transport, for example in combination with an eccentric system and a link system.

As described above, the structure 20 defines a conveying channel 22 (FIG. 1A) for conveying molten zinc extracted from the coating vessel 3 toward the storage tank 2 together with the deflector 12. . The conveying channel 22 is horizontally constrained by the lug 23 and protrudes upwards from the side of the deflector 12, as shown for example in FIG. 4. In a preferred variant, the lug 23 is arranged along the shape of the deflector at the horizontal edge of the deflector 12. The first end of the lug 23 is disposed below the upper end 13 of the deflector; The second end is arranged at and along the shape of the lower end 14 of the deflector.

The structure 20 is configured to define a longitudinal flared opening 21 at the upper end, the opening extending transversely to the chamber 6 to substantially the entire thickness of the chamber, in which the upper end of the deflector is located. 13 is disposed (FIGS. 1A and 9). The longitudinal flared opening 21 functions as a funnel member or an open expansion tank to intercept a large amount of liquid zinc from the bottom of the coating vessel 3 in both the start or stop phase and in the maintenance or emergency phase. Do it. For example, in the start-up step, before the molten zinc reaches the so-called support threshold or head supported by the magnetic field in the coating vessel 3 thereon, the molten zinc is not yet properly supported and is discharged from the opening 4. do. The support threshold or head is defined according to the size of the coating vessel 3 and the strength of the magnetic field. In the case of maintenance or emergencies, for example in the case of a loss of magnetic field, the longitudinal flared openings 21 allow for the intercepting and management of large amounts of molten zinc in the funnel being exhausted entirely.

The structure 20 (FIGS. 7, 8) consists of two half members 20 ', which are independent from the deflector 12 and two opposing side walls 6' of the chamber 6 (FIG. 9). It is fixed integrally with the upper end 27 thereof in contact with each other by the respective horizontal support plates 28. Below the horizontal support plate 28, horizontal drainage channels 29 are provided in each half member 20 ′. The deflector 12 is arranged in a space in which two pairs of horizontal support plates 28 contact each other, in the center of the narrowing area 37 (FIGS. 6 and 9) of the longitudinal flared opening 21, Since it extends far to the bottom 14 with the same thickness L (FIG. 9), the horizontal drain channel 29 preferably melts beyond the thickness of the deflector and over this thickness of the conveying channel 22. Allow portions of zinc to be transported.

On the one hand, at the lower end, the structure 20 is configured to define longitudinal end channels 24, 25 (FIGS. 1A, 7), the outlet of which is discharged from the conveying channel 22 and the horizontal drain channel 29. It is close to a funnel member 26 that collects molten zinc to pour into the storage tank 2 below. The funnel member 26 is optional and if it is not provided the discharged molten zinc passes directly into the storage tank 2.

The conveying channel 22 disposed on each side of the vertical feed plane X is substantially the outer profile of the deflector 12 in the stretch between the longitudinal flared opening 21 and the end channels 24, 25. Follow.

In a preferred variant, as shown in FIGS. 1A, 7 and 8, the end channel 25 has a bridged configuration 40, whereby molten zinc arriving from the transfer channel 22 and the horizontal drainage channel 29 ) Is horizontally redirected and discharged directly into the funnel member 26 or into the storage tank 2 to prevent fouling of the strip entering the chamber 6 and moving to the redirecting roller 7. The span of the bridge is preferably greater than the thickness of the strip 5 entering the chamber 6.

This end channel, thus having a bridged configuration, is arranged at least in the region between the horizontal opening 41 (FIG. 1 a) and the turning roller 7 of the chamber 6, through which the strip 5 enters the chamber after pretreatment. Enter. The half member 20 '(FIG. 7, 8) of the structure 20 under each upper part 27 has the center part 36 and the lower part 35, respectively. The central portion 36 has a profile corresponding substantially to the central portion 15 of the corresponding deflector 12 and is spaced appropriately therefrom such that the conveying channel 22 is restricted on the side by the lug 23 and defined. do.

The chamber 6 comprising a storage tank 2 and connecting with an electromagnetic zinc plating machine 10 comprising an inductor 11 and a coating vessel 3 preferably comprises the chamber and the storage tank 2. A heating means is provided for maintaining the place at a predetermined temperature, which temperature is substantially the same as the temperature of the coating material in the molten state. The temperature of all members of the chamber, such as the inner wall and the fixed and / or movable members, is kept constant at about 460-490 ° C., for example depending on the chemical composition of the ingot of the coating material. The strip 5 is already preheated to the chamber 6 at a temperature substantially equal to or above the holding temperature of the coating material in the molten state.

The fact that the storage tank 2 for molten zinc is provided in the same place as the chamber 6 determines the energy from the storage tank or zinc pot 2 which contributes to quickly raising the entire single position to a predetermined temperature. .

Guide rollers 7 and 8 made of steel are preferably provided with a coating of ceramic material or chromium oxide or boron nitride or obtained by welding filler (for example a trasferred arc). In this way, non-uniform production of iron-zinc alloy which is very difficult and difficult to remove is prevented and adhesion of droplets of liquid zinc on the guide roller is prevented, thereby preventing the formation of imprint on the strip by the non-uniformity on the roller. Other members, for example the wall of the chamber 6, may be coated with ceramic tiles.

The first heating means of the chamber 6 is provided on at least one of the two guide rollers 7, 8.

In the first variant, the cylindrical turning roller 7 has the same axis as the roller 7 and is provided with a hollow cylindrical jacket 7 '. The hollow cylindrical jacket 7 ′ is provided with a plurality of longitudinal grooves or holes 30 for accommodating the electrical resistors, which are obtained in the thickness of the jacket and are respectively connected to appropriate power means. The longitudinal groove 30 preferably has an axis parallel to the axis of rotation of the forwarding roller 7 and is arranged along a horizontal horizontal plane, the number of which and the distance between one groove and the next groove are suitably defined so that the strip 5 It ensures a homogeneous temperature on the outer surface of this moving roller 7.

On the other hand, a second variant (not shown) is provided in which at least three fixed resistors or radial combustion burners are arranged in the groove part of the roller 7 in the hollow cylindrical turning roller 7.

In both variants, droplets of molten zinc that are likely to fall on the outer surface of the turning roller 7 do not adhere to the heated outer surface, but remain liquid and slide to form a funnel member 26 or storage tank ( 2) Fall directly into the stomach.

In addition, in all variants the stabilizing roller 8 may be provided with heating means, and in limited cases may match a suitably coated resistor.

The guide rollers 7, 8 can preferably be mounted on detachable hubs. The hollow jacket 7 'represents the wear area of the forward roller system, and the guide rollers 7 and 8 preferably both have bearings 31 and 32 on the outside of the chamber, respectively, so that the entire machine does not have to be disassembled. Allow for maintenance and / or replacement without excessive time loss.

Second heating means of the chamber 6 are also provided in other parts of the chamber.

The second heating means is preferably a heating plate 33, for example provided with longitudinal grooves or holes 34 for receiving respective electrical resistors connected to power means suitable for their thickness.

In a preferred variant the heating plate 33 is arranged in proximity to the central part 36 and in close proximity to the lower end 35 of the half member 20 ′ of the structure 20 of the intercept and transfer system (FIGS. 1 and 7). Is placed.

Another heating plate 33 may be provided in proximity to the outer surface of the funnel member 26 (FIG. 1) and the storage tank 2 (FIGS. 1 and 2).

The chamber 6 is preferably provided with two sealing systems, wherein the atmosphere in the sealing system is inert by an inert gas, ie nitrogen, that is less than the external atmospheric pressure to prevent the presence of oxygen to reduce the formation of DROSS. It is introduced and maintained at high pressure.

A first sealing system (not shown) is provided in the horizontal opening 41 (FIG. 1A) of the chamber 6, in which the strip 5 enters the chamber 6 after pretreatment.

On the other hand, the second sealing system consists of liquid zinc in the coating vessel 3 and does not allow leakage of the inert gas present in the chamber 6.

In the passage region between the chamber 6 and the coating vessel or the grind 3, the strip 5 preferably passes, and is preferably thermally blocked, for example a channel 45 thermally blocked with ceramic material. ) Is provided. The channel 45 is fixed to the bottom of the coating vessel 3 and has a first end in communication with the opening 4 of the coating vessel 3, and communicates with the chamber through the top wall of the chamber 6. Has a second end.

The flared opening 21 and the entire intercept and conveying system 9 preferably have a thickness L ′, which is equal to two of the deflector 12 (FIG. 9) and the opening 4 of the coating vessel 3. It is larger than the thickness L of the die. The thickness of the channel 45 is at least equal to the opening 4 and smaller than the thickness L 'of the flared opening 21.

In supplying molten zinc to the coating vessel 3, the coating vessel 3 may receive molten zinc from the storage tank 2, which may also constitute a molten tank of zinc ingots. In the start-up phase, zinc ingots are loaded directly into the storage tank 2 and lean on the movable drawers which are moved by hydraulic or pneumatic pressure.

The entire chamber 6 comprising the storage tank 2 is preferably modular and allows the addition of a furnace that offers the possibility of continuously loading zinc. Each furnace is provided with a recirculation pump and the crucible is arranged to be immersed in the molten material fed into the furnace.

Alternatively, the storage tank 2 may be different from the melting tank for the zinc ingot where pure molten zinc is taken for introduction into the coating vessel 3 or funnel. In this way, the delivery step in which pure molten zinc is transferred from the melting tank to the coating vessel 3 is separated from the recovery of the molten zinc coming from the coating vessel 3. The recovered molten zinc may have impurities and therefore may need to be reprocessed and / or refiltered by, for example, a suitably heated settling bath to purify the molten coating material. However, the pump 40 shown in FIG. 2 is configured to operate below the discharge level of the reservoir 2 so that the pump 40 always melts clean in the reservoir because the dross is accumulated on the surface portion of the reservoir. Inhale close to the floor with zinc.

Referring to FIG. 1, the continuous strip 5 is released from a skein (not shown) and is subject to the conventional pretreatment upstream of the first sealing system. After the pretreatment, the strip 5 enters the chamber 6 and is guided by the guide rollers 7, 8 toward the longitudinal opening or slot 4, the guide rollers 7, 8 having an electromagnetic zinc plating machine ( 10) is supplied to the bottom of the coating vessel (3). The opening 4 allows the strip 5 to be introduced into the molten zinc bath provided in the container 3, which defines the top side or the top meniscus. The strip 5 moves along the direction extending through the jaw. Movement of the strip 5 through the bath allows the strip 5 to be coated with the molten zinc layer from which the bath is constructed. From the downstream of the top surface of the bath comes a coated strip. The coating vessel 3 has an open top end through which the coated strip moves in the upward direction.

The controller for controlling the thickness of the coating is of pneumatic or electromagnetic type, which is generally used to obtain the desired basis weight on the strip and is placed on top of the coating vessel 3. Downstream of the controller is a reel (not shown) where the coated strip cooled on the reel is wound into a coil, which is then removed by the reel.

During the whole coating process, an inert atmosphere is preferably provided in a single location, the single location being defined by the chamber 6 and the storage tank 2, the pressure being higher than the external pressure of the site, And transferring molten zinc out of the opening 4 at the bottom of the storage tank 3 to the storage tank 2 by means of the provided intercept and transfer system 9.

In normal operation of the plant, droplets of molten zinc coming from the opening 4 will slide into the strip 5 until it reaches the deflector 12, which leads to the conveying channel 22, and eventually to the end channel 24 and 25).

In the case of a plant in the start-up or stop phase, abundant amounts of molten zinc from the openings 4 flow through the channel 45 into the longitudinal flared openings 21, thus conveying channels 22 and end channels. (24 and 25).

The temperature within the single position is maintained at substantially the same level as the holding temperature of the coating material in the molten state during steady state operation.

Claims (15)

A plant for coating a flat metal product (5) by continuous hot dip plating, the plant comprising
A storage tank 2 for containing the molten coating material;
A coating container (3) adapted to receive and contain a molten coating material, disposed above the storage tank (2), and provided with an opening (4) at the bottom to pass a flat metal product to be coated;
A chamber 6 disposed below the coating vessel 3 and provided with guide rollers 7, 8 for guiding the flat metal product 5 towards the opening 4, and
The storage tank 2 is disposed below the guide rollers 7 and 8 and inside the chamber 6 so that the chamber and the storage tank form a single position,
In the chamber 6 is provided an intercepting and conveying system 9 disposed between the coating vessel 3 and the storage tank 2 to intercept molten coating material leaking out of the opening 4. And transported to the storage tank (2),
The intercept and transfer system has a structure defining a cavity facing the storage tank 2; The cavity at least partially receives at least one first guide roller 7 adapted to be turned as the flat metal product 5 enters the chamber 6, the upper part of the first guide roller 7 being And fully receive the at least one second guide roller 8 arranged to deflect and stabilize the flat metal product which is disposed in and supplied toward the opening 4, wherein the guide rollers 7, 8 and the opening ( The flat metal product 5 which is fed towards 4) is completely protected from the droplets of the molten coating material during the steady state operation of the plant, or a large amount of the molten coating material in both the starting or stopping phase and in the maintenance or emergency phase. Is completely protected from falling,
plant.
The method according to claim 1,
The intercept and transfer system 9 defines channels 22 which branch from one another in the direction from the coating vessel 3 to the storage vessel 2,
plant.
3. The method of claim 2,
The channel 22 is by means of a pair of deflectors 12 having an upper end 13 defining a gap for passing the flat metal product 5 in the vertical direction, and external to and in relation to the deflector. Defined by a structure 20 independent of
plant.
The method of claim 3, wherein
Each of the deflectors 12 is arranged on each side of the vertical feed plane X of the flat metal product 5 and connected to two opposing side walls 6 'of the chamber 6,
plant.
5. The method of claim 4,
Each of the structures 20 is configured to define a flared opening 21 extending to the chamber 6 in the transverse direction at the upper end thereof, and the upper end 13 of the deflector 12 disposed therein. ,
plant.
6. The method according to any one of claims 3 to 5,
Provided with adjusting means for adjusting the passage gap,
plant.
The method according to claim 6,
The gap adjusting means is configured to move the two support shafts 17 of the deflector 12 and is arranged parallel to the vertical feed plane X, each support shaft 17 having its respective front Which is integrally fixed with the scent 12 and connected to the two side walls 6 ′ opposite the chamber 6,
plant.
The method according to any one of claims 1 to 7,
A heating means is provided in the chamber 6,
plant.
The method of claim 8,
A first heating means is provided on at least one of the guide rollers 7, 8, the first heating means preferably being a plurality of grooves provided in the hollow jacket 7 ′ of the first guide roller 7. (30) is an electrical resistor housed in,
plant.
The method of claim 9,
A second heating means proximate to the outer wall of the structure 20 is provided, preferably the second heating means is a heating plate 33,
plant.
11. The method according to any one of claims 1 to 10,
The support of the guide rollers 7, 8 has a bearing on the outside of the chamber 6,
plant.
12. The method according to any one of claims 1 to 11,
The coating vessel 3 is part of a suitable electromagnetic device 10 capable of keeping the bath of the molten coating material semi-injured.
plant.
13. The method according to any one of claims 1 to 12,
A channel 45 is provided, which communicates with the opening 4 of the coating vessel 3 at the first end and with the chamber 6 at the second end, from the chamber 6 with the coating vessel. (3) suitable for passing the flat metal product 5 into,
plant.
A coating method for flat metal products by continuous hot-dip plating by means of a plant according to claim 1, wherein the method comprises:
Providing the single location with an inert atmosphere that is higher than the pressure outside the location;
Feeding the flat metal product 5 into the chamber 6 by guiding it towards the coating vessel 3 by means of the guide rollers 7, 8,
Coating said flat metal product in said coating vessel (3);
Including;
The melt coating material leaking out of the opening 4 at the bottom of the coating vessel 3 is intercepted into the storage tank 6 by the intercept and transfer system 9 provided to the chamber 6 and Conveyed to protect the guide rollers 7, 8 and to protect the flat metal product 5 which is fed towards the opening 4 inside the cavity of the structure of the intercept and conveying system,
Way.
15. The method of claim 14,
Wherein the single location is maintained at a suitable temperature to keep the coating material in the molten state,
Way.

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