WO2016020546A1

WO2016020546A1 - Heating furnace for metal bars

Info

Publication number: WO2016020546A1
Application number: PCT/EP2015/068367
Authority: WO
Inventors: Mario Barachetti
Original assignee: I.C.M.I. S.R.L.
Priority date: 2014-08-08
Filing date: 2015-08-10
Publication date: 2016-02-11
Also published as: EP3177746A1

Abstract

Module (1) for heating furnaces (10) for metal bars (101, 102, 103), which comprises: a combustion chamber (2) with longitudinal development along an advancement direction (4), delimited by a body of refractory material (3) and having an inlet section (20) and an outlet section (200); means for supporting and advancing said metal bars (101, 102, 103) along said advancement direction (4) from said inlet section (20) to said outlet section (200) on an advancement plane (6), arranged in said combustion chamber (2); at least a pair of burners (11, 12) with a first (11) and a second (12) burner which face into said combustion chamber (2) above said advancement plane (6); the axes of said first (11) and second (12) burner being oriented tangentially with respect to said combustion chamber (2); said first (11) and second (12) burner being both inclined in the direction of said inlet section (20) with respect to a transverse plane (5) perpendicular to said advancement direction (4).

Description

HEATING FURNACE FOR METAL BARS.

DESCRIPTION

The present invention relates to a module for heating furnaces for metal bars as well as to a heating furnace for metal bars which comprises one or more of said modules. In particular, the present invention relates to a module for heating furnaces for metal products, such as steel bars, for molding line with hot cutting, as well as to the relative furnace. More in particular, the present invention relates to a heating furnace for metal products, such as steel bars, for molding line with hot cutting, wherein the bars are only heating using gas burners.

As known, molding lines with hot cutting of metal bars, such as steel, have a heating furnace located upstream of the cutting station.

Known heating furnaces normally make use of mixed energy, which involves an initial continuous heating step in gas heating furnaces, wherein gas (usually methane or LPG) is burnt up to have a temperature of the bars of about 1100 °C, and a final heating step in induction furnaces, wherein the bars are brought to a temperature of about 1250 °C through circular section inductors.

In practice, in existing plants, about 80% of the heat input required to heat the bars takes place with energy at relatively low cost (gas), while the remaining 20% takes place through induction, thus using electric energy which has relatively higher costs compared to gas.

The necessity to use such mixed systems is mainly dictated by the non-optimal performance of the existing gas heating furnaces, which do not allow reaching the desired temperatures for machining the bars (about 1250 °C) optimally.

Gas heating furnaces of the known type normally have a combustion chamber formed by a tunnel extending longitudinally within which the metal bars are made to advance, through a system of horizontal rollers that have a V-shaped seat for housing said bars. A plurality of gas burners face the tunnel and are usually oriented so as to direct the jet of the flame toward the surface of the bar.

An example of such gas heating furnaces of the known type is described in patent application WO2007088439, which relates in particular to an angular orientation system of the burners, by means of levers and rods, in order to optimally direct the burners toward the surface of the bars, adapting itself to the different sizes of the cross sections of said bars.

Even resorting to complicated and relatively expensive systems of the type described in the cited patent application, the gas heating furnaces of the known type are not always able to provide the heat input required to bring the bars to the molding temperature of about 1250 °C in a cost-effective manner. There is also to be noted that the non-optimal combustion and the presence of oxygen inside the tunnel involves phenomena of surface oxidation of the bars that would be highly desirable not to have.

Another problem of the heating furnaces of the known type is related to the transport system based on horizontal rollers with V-shaped notch. In the presence of square-section (or rectangular) bars, the side walls of the bar are supported by and in contact with the entire surface of the V-shaped notch. Since the peripheral speed of the roller at the V-shaped surface varies depending on the diameter, a sliding of the roller surface occurs on the side of the square bar, with rapid wear of the rollers and consequent need for maintenance/replacement work.

Finally, it should be noted that the heating furnaces of the known type are considerably bulky and are difficult to adapt to different operational needs (for example, shapes and dimensions of the bars).

It is therefore clear that the gas heating furnaces of the known type have a series of problems that make the exercise thereof not optimal.

Based on these considerations, the main task of the present invention is to provide a heating furnace for metal bars that overcomes the drawbacks and problems described above.

Within this task, an object of the present invention is to provide a heating furnace for metal bars which allows using only gas as a source of heat input, eliminating the need for the final electromagnetic induction heating.

Another object of the present invention is to provide a heating furnace for metal bars that has a higher thermal efficiency compared to the current furnaces that use gas heating, with consequent saving on costs.

Yet another object of the present invention is to provide a heating furnace for metal bars wherein there is a reduced oxidation of the surface of the bar.

Yet another object of the present invention is to provide a heating furnace for metal bars wherein there is improved uniformity of heating between the surface and the core of the material to be heated, resulting in increased product quality, in particular for alloy steels. Another object of the present invention is to provide a heating furnace for metal bars that is usable with a wide range of round or square section bars.

A further object of the present invention is to provide a heating furnace for metal bars wherein the phenomena of wear by sliding of the advancement rollers of said bars is prevented.

Yet another object of the present invention is to provide a heating furnace for metal bars that is standardized and able to be easily adapted to the numerous and variable requirements of potential customers.

Yet another object of the present invention is to provide a heating furnace for metal bars that is easily transportable, even in containers, with reduced time of installation.

Yet a further object of the present invention is to provide a heating furnace for metal bars that is already ready for future upgrades for any increases in production.

Last but not least, another object of the present invention is to provide a heating furnace for metal bars that has high reliability and is easy to manufacture at competitive costs.

This task, as well as these and other objects that will become apparent hereinafter, are achieved through a module for heating furnaces for metal bars, which is characterized in that it comprises:

a combustion chamber with longitudinal development along an advancement direction, delimited by a body of refractory material and having an inlet section and an outlet section;

means for supporting and advancing said metal bars along said advancement direction from said inlet section to said outlet section on an advancement plane, arranged in said combustion chamber;

at least a pair of burners with a first and a second burner which face into said combustion chamber above said advancement plane;

the axes of said first and second burner being oriented tangentially with respect to said combustion chamber;

said first and second burner being both inclined in the direction of said inlet section with respect to a transverse plane perpendicular to said advancement direction.

In fact, it has been seen that a module for heating furnaces for metal bars thus conceived allows providing a heating furnace for metal bars having a set of features and properties that allow overcoming the drawbacks and problems described above.

In particular, it has been seen that by using one or more modules according to the present invention it is possible to provide a furnace which allows rapid heating of the metal bars, such as round or square steel rods, up to the temperature of hot molding of 1250-1280 °C, without any need for induction heating.

In other words, as better explained hereinafter, the geometry of the chamber and the position of the burners are such as to form a spiral of circular cross section with "the flame" of the burners and the related combustion products which surrounds the bar to be heated.

The spiral movement of the fumes, in rotation around the bar to be heated and their advancement in countercurrent with respect to the advancement movement of the bar, leads to a significant increase in the heat exchange (conduction and radiation) between the combustion fumes and the material to be heated, significantly reducing the heating time.

In practice, unlike conventional furnaces, the jet exiting each burner is not oriented directly toward the bar and toward the center of the combustion chamber but along a direction tangential to the section of the combustion chamber. Moreover, again unlike conventional furnaces, the orientation of the burners and of the related jet is not perpendicular to the advancement direction of the bars but inclined and in countercurrent with respect to their advancement direction. In this way, a uniform spiral circulation of the fumes inside the combustion chamber is generated, in countercurrent to the advancement direction of the bars, with a resulting increase in the combustion and heat exchange efficiency.

At the same time, it has been verified that a module for heating furnaces thus conceived allows a considerable reduction of the phenomena of oxidation on the surface of the bars, as these are completely enveloped by the combustion fumes and are not in contact with the oxygen contained in the atmosphere, which is the main element of the oxidation of the bars. The modules for heating furnaces for metal bars, according to the present invention, have the advantage of exploiting a primary energy source, i.e. gas, of greater availability compared to the availability of electric current, which moreover requires transformation cabins from the line distribution voltage (medium voltage) to the use voltage. Moreover, in the case of replacement of an induction line, the customer has an availability of electric energy that can be used for other purposes.

A widely preferred embodiment of the module for heating furnaces for metal bars, according to the present invention, provides for the presence of a plurality of pairs of first and second burners that face in said combustion chamber above said advancement plane and which are oriented and inclined as described above.

In particular, it has been seen that it is particularly advantageous to have an orientation of the axes of said first and second burner that is not exactly opposed. In other words, the angle formed by the axes of said first and second burner, measured from the top of the module, should preferably be less than 180°, more preferably between about 70° and about 110°, for example 90 + 5°.

According to a particularly advantageous embodiment of a module for heating furnaces for metal bars, according to the present invention, said first and second burner have the same inclination with respect to said transverse plane perpendicular to said advancement direction. Moreover, preferably, the point of facing of said first and second burner in said combustion chamber lies on a same transverse plane perpendicular to said advancement direction.

In other words, according to this embodiment, the first and second burners of each pair of burners are specularly arranged with respect to a longitudinal plane passing by said advancement direction. In fact, it has been seen that with this configuration, the spiral of hot fumes that is formed around the bars to be heated is more uniform. Alternative embodiments, in which said first and second burners of each pair of burners are arranged offset, are however possible.

A particularly preferred embodiment of a module for heating furnaces for metal bars, according to the present invention, provides for said combustion chamber to have a substantially circular section.

Preferably, in the module for heating furnaces for metal bars, according to the present invention, said means for supporting and advancing comprise at least a pair of rollers and preferably a plurality of rollers, with a first and a second roller which enter into said combustion chamber above said advancement plane and with their respective axes converging in a point below said advancement plane, the lateral surfaces of said first and second roller defining a support surface for said metal bars.

In particular, according to this embodiment, said first and second roller are preferably arranged symmetrically with respect to a longitudinal vertical plane passing through said advancement direction and perpendicular to said advancement plane.

In fact, it has been seen that a system for support and advancing the metal bars thus implemented allows preventing the phenomena of wear of the rollers of the advancement systems of the known type.

According to this embodiment of a module for heating furnaces for metal bars, according to the present invention, the bars are preferably supported by pairs of inclined rollers arranged on the roof of the furnace and with axes converging in a point below the advancement plane of the bars inside the combustion chamber. Conveniently, the rollers have a cooling system with internal circulation of water.

In this way, the inclined position and the circular shape of the rollers allows having a constant peripheral speed of the lateral surfaces of said first and second roller that form the support surface for the advancing bars, making it possible to advance also the bars with square section without the occurrence of scraping between the lateral surface of the roller, which constitutes the support surface for the bar, and the surface of the bar itself.

In general, it can therefore be stated that a module for heating furnaces for metal bars, according to the present invention, comprises means for supporting and advancing said bars comprising at least a pair of rollers rotating about respective axes of rotation, said axes being converging at a point below the advancement plane of the bars in the combustion chamber, at least a portion of the lateral surface of said rollers defining a support surface for said bars, the peripheral speed of the lateral surfaces of said rollers at said support surface being the same along all of said support surface.

Therefore, in a further aspect thereof, the present invention also relates to a module for heating furnaces for metal bars, which is characterized in that it comprises:

said means for supporting and advancing said metal bars comprising a pair of rollers with a first and a second roller which enter into said combustion chamber above said advancement plane and with their respective axes converging in a point below said advancement plane, the lateral surfaces of said first and second roller defining a support surface for said metal bars. For the purposes of the present invention, the convergence of the axis of said first and second roller is considered with regard to their projection on a transverse plane perpendicular to said advancement plane.

According to a particular embodiment of the module according to the present invention, one of said rollers of said pair of rollers is inclined toward said inlet section and the other one of said rollers of said pair of rollers is inclined toward said outlet section.

The inclination of the rollers placed on the roof of the furnace with respect to the section perpendicular to the axis of the advancement direction of the bars (i.e. toward the inlet section or toward the outlet section), allows to obtain a movement according to a helicoidal generatrix that, in addition to the advancement of the bars, causes a rotation of the bars on their own axis.

The rotation of the bars around their axis increases the heating uniformity of the bars within the furnace and allows to perform a uniform and controlled cooling on the bars at the exit of the furnace. In other words, the rotation of the bars on their axis allows to perform uniform and homogeneous cooling treatments on the bars at the exit of the furnace, thereby reducing their possible deformation.

Such solution is a great improvement with respect to the current V-rollers with horizontal axis that normally have a much greater diameter, thereby limiting the efficiency of the heating system, both as an important addition of mass to be heated (weight of the rollers), and in terms of size of the combustion chamber (needed to hold the rollers); moreover the chamber has to be provided with openings of considerable dimensions which are necessary for the extraction of the rollers.

Thus, for a given helical movement of the bars, the new solution eliminates all the dimensional constraints for the chamber due to the V-rollers with a horizontal axis, resulting in a notable increase in the efficiency of the system and in an important economic saving of the cost of the rollers.

In a particularly preferred embodiment of the module for heating furnaces for metal bars according to the present invention, said burners comprises a flameless burner and/or an oxygen-based burner.

As known, the so-called "flameless" burners are based on a combustion process of a particular type in which the combustion air and the fuel are locally mixed with the products of combustion which are suitably recirculated. In this way there is provided a process of complete oxidation of the fuel by the combustion, without the formation of a flame front, providing a high thermal uniformity inside the combustion chamber.

In practice, with the flameless burners, combustion occurs with the absence of a flame defined and apparent during the course of the reaction of combustion, since the combustion reaction is distributed within the reaction chamber and not more concentrated on a front of flame. The enlargement of the region of combustion causes a marked homogenization temperature which results, in turn, a flattening of the temperature peaks responsible, among other things, the formation of nitrogen oxides of thermal origin.

With the oxygen-based burners, pure oxygen is used instead of air as oxidizing medium. This technology allows a greater efficiency of the combustion process due to the elimination of nitrogen which, as known, constitutes about 80% of the air. In addition, at the same temperature, the energy that is absorbed by the metal is higher than the conventional air burners.

In order to reduce the risk of a flame particularly intense at high temperature that may occur with the oxygen-based burners, while ensuring a high uniformity of temperature and reducing the consumption of fuel, it is highly preferable to use in the module according to the present invention oxygen-based flameless burners. In practice with such burners jets of oxygen are injected at high speed by generating a rapid mixing of these with the fumes inside the furnace, with a high turbulence and a peak temperature lower than conventional oxygen systems, while ensuring a great energy efficiency.

Moreover, the present invention also relates to a heating furnace for metal bars which comprises one or more modules as described. The number of modules, as well as the number of pairs of burners in each module, can vary according to the needs.

Further features and advantages of the present invention will become more apparent from the description of preferred but non-exclusive embodiments of a module for heating furnaces for metal bars, according to the present invention, which are illustrated by way of example in the accompanying drawings, in which:

figure 1 shows a perspective view of an embodiment of a module for heating furnaces for metal bars according to the present invention;

figure 2 shows a perspective view of a longitudinal section of a module for heating furnaces for metal bars according to the embodiment in figure 1 ;

figure 3 shows a first plan view of a transverse section of a module for heating furnaces for metal bars according to the embodiment in figure 1 ;

figure 4 shows a perspective view of a transverse section of a module for heating furnaces for metal bars according to the embodiment in figure 1 ;

figure 5 shows a second plan view of a transverse section of a module for heating furnaces for metal bars according to the embodiment in figure 1 ;

figure 6 shows a lateral view with cut-out portions of a module for heating furnaces for metal bars according to an alternative embodiment of the present invention;

figure 7 shows a top plan view of a heating furnace for metal bars comprising a plurality of modules according to the present invention.

With reference to the accompanying figures, a module for heating furnaces for metal bars, according to the according to the present invention, designated with reference numeral 1, comprises, in its most general embodiment, a combustion chamber 2 with longitudinal development along an advancement direction 4 of the bars.

As shown in the accompanying figures 3 and 5, the bars can have different shapes and sizes.

They can for example be bars with a circular section, both with relatively small diameter 101 and with relatively larger diameter 102, or bars with a square section 103.

The combustion chamber 2 is delimited by a body of refractory material 3 and has an inlet section 20 and an outlet section 200 along said advancement direction 4.

Inside the combustion chamber 2 there are arranged means for supporting and advancing said metal bars 101, 102, 103 along said advancement direction 4 from said inlet section 20 to said outlet section 200 on an advancement plane 6.

Moreover, at least a pair of burners 12 are provided, with a first 11 and a second 12 burner which face into said combustion chamber 2 above said advancement plane 6. For the purposes of the present invention, the term "burner" refers to both the actual burner and to the relevant conduit formed in the body of refractory material 3 which flows into said combustion chamber 2.

As is particularly apparent from figures 3 and 5, one of the peculiar features of module 1 for heating furnaces for metal bars 101, 102, 103, according to the present invention is given by the fact that axes 110 and 120 of said first 11 and second 12 burner are oriented tangentially with respect to said combustion chamber 2. This constitutes a first significant difference compared to the furnaces of the known type, in which the burners are substantially oriented toward the bars, that is to say, towards the center of the combustion chamber.

Another peculiar feature of module 1 for heating furnaces for metal bars 101, 102, 103, according to the present invention, which is particularly clear from figure 2, is given by the fact that axes 110 and 120 of said first 11 and second 12 burner are both inclined in the direction of said inlet section 20 with respect to a transverse plane 5 perpendicular to said advancement direction 4.

In practice, contrary to the furnaces of the known type in which the burners are substantially perpendicular to the advancement direction of the bars, in module 1 according to the present invention burners 11, 12 are inclined and in countercurrent with respect to the advancement direction 4 of bars 101, 102, 103. In this way, as mentioned above, the position and orientation of the burners are such as to generate a spiral pattern of the flame of the burners and of the related combustion products around bars 101, 102, 103 advancing within the combustion chamber 2, with the consequent advantages in terms of increase in the heat exchange and reduction of oxidative phenomena.

Preferably, as shown in the accompanying figures, modules 1 for heating furnaces for metal bars 101, 102, 103, according to the present invention, comprise a plurality of pairs 11, 12; 21, 22; 31, 32, 41, 42, 51, 52 of first 11, 21, 31, 41, 51 and second 12, 22, 32, 42, 52 burners. In the embodiment shown in the accompanying figures there are five pairs of burners but their number may be different depending on the application requirements.

With particular reference to figure 3, a preferred embodiment of a module 1 for heating furnaces for metal bars 101, 102, 103, according to the present invention, provides that the angle formed by the axes of said first 11, 21, 31, 41, 51 and second 12, 22, 32, 42, 52 burner is less than 180°. In other words, the first 11, 21, 31, 41, 51 and second 12, 22, 32, 42, 52 burners of each pair of burners 11, 12; 21, 22; 31, 32; 41, 42; 51, 52 need not be exactly opposite one another (and therefore with the respective axes at 180°) but oriented so as to form an angle different from 180°.

In the embodiment shown in figure 3, the angle between axes 110 and 120 of burners 11 and 12 is about 90°. Values in the range between 70 and 110°, for example 90 + 5°, are to be considered preferred. As is apparent from figure 3, for the purposes of the present invention, the angle formed by axes 110 and 120 of said first 11 and second 12 burner must be understood as measured from the top of module 1.

With particular reference to figure 2, a preferred embodiment of a module 1 for heating furnaces for metal bars 101, 102, 103, according to the present invention, provides that said first 11, 21, 31, 41, 51 and second 12, 22, 32, 42, 52 burner have the same inclination with respect to a transverse plane 5 perpendicular to said advancement direction 4. In other words, according to this embodiment, the axes of the first burners 11, 21, 31, 41, 51 are parallel and angled with respect to the transverse plane 5, in countercurrent with respect to the advancement direction 4, and the second burners 12, 22, 32, 42, 52 are also parallel and angled, with respect to the transverse plane 5, in countercurrent with respect to the advancement direction 4.

Moreover, as is particularly apparent from figure 2, for each pair of burners 11, 12; 21, 22; 31, 32; 41, 42; 51, 52, the point of facing of the first 11, 21, 31, 41, 51 and second 12, 22, 32, 42, 52 burners inside the combustion chamber 2 preferably lies on a same transverse plane 5 perpendicular to said advancement direction 4. In other words, in each pair of burners 1, 12; 21, 22; 31, 32; 41, 42; 51, 52, the first burner 11, 21, 31, 41, 51 is arranged specularly to the second burner 12, 22, 32, 42, 52 with respect to a longitudinal plane passing through said advancement direction 4.

However, alternative embodiments are possible in which, for each pair of burners 11, 12; 21, 22; 31, 32; 41, 42; 51, 52, the first burner 11, 21, 31, 41, 51 is arranged offset with respect to the second burner 12, 22, 32, 42, 52 along the advancement direction 4.

A particularly preferred and advantageous embodiment of a module 1 for heating furnaces for metal bars 101, 102, 103, according to the present invention, provides for the combustion chamber 2 to have a substantially circular section. In this way, the regular geometry of the combustion chamber 2 contributes to ensuring, together with the orientation of burners 11, 12; 21, 22; 31, 32; 41, 42; 51, 52, the uniform spiral pattern of the flame and of the combustion products within the same, with the advantages mentioned several times. With particular reference to figures 4 and 5, a particular embodiment of a module 1 for heating furnaces for metal bars 101, 102, 103, according to the present invention, provides that said means for supporting and advancing comprise at least a pair of rollers 61, 62 with a first 61 and a second 62 roller which enter into said combustion chamber 2 above said advancement plane 6 and which rotate about a respective axis 610, 620.

In this embodiment, axes 610, 620 of the first 61 and second 62 roller are converging at a point below said advancement plane 6 and at least a portion of the lateral surfaces 65, 66 of said first 61 and second 62 roller defines a support surface for said metal bars 101, 102, 103. In this way, as can be seen in particular from figure 5, the peripheral speed of the lateral surfaces 65 and 66 of said rollers 61 and 62 at the support surface of bars 101, 102, 103, and in particular of the square bars 103, is constant and is the same along all of the support surface, thus preventing the typical phenomena of scraping and wear of the means for supporting and advancing of the conventional type.

With particular reference to figure 5, said first 61 and second 62 roller are arranged symmetrically with respect to a longitudinal vertical plane 7 which passes by said advancement direction 4 and which is perpendicular to said advancement plane 6. Moreover, preferably, a module 1, according to the present invention, preferably comprises a plurality of pairs of first and second rollers. For example, in the accompanying figures, modules 1 comprise two pairs 61, 62; 71, 72, of first 61,71 and second 62, 72 rollers; it is of course possible to use three or more pairs of rollers for each module, depending on the length of the same module and/or on the length of the bars to be machined.

With reference to figure 6, according to an alternative embodiment of a module 1 for heating furnaces for metal bars 101, 102, 103, according to the present invention, the first roller 61 is inclined toward the inlet section 20 of the combustion chamber 2, while the second roller 62 is inclined toward the outlet section 200. In this way, the rollers 61 and 62, in addition to the advancement of the bar, imparts a rotation of the bar on its own axis thereby greatly increasing the uniformity of the heat treatments, both inside and outside the combustion chamber 2, bringing about the above-mentioned advantages

Preferably, as shown in figure 6, in addition to the first pair of rollers 61 and 62, the module 1 for heating furnaces for metal bars 101, 102, 103 according to the present invention further comprises at least a second pair of rollers, with a third 611 and a fourth 621 roller which enter into said combustion chamber 2 above said advancement plane 6. As clearly shown in the above-mentioned figures, the third roller 611 is inclined in the opposite direction with respect to said first roller 61, while the fourth roller 621 is inclined in the opposite direction with respect to said second roller 62.

In other words, considering the pair of rollers 61 and 611 (or 62 and 622), their axis are diverging from each other below said advancement plane 6, one (i.e. the first roller 61) being directed toward the inlet section 20 of the combustion chamber 2, the other one (i.e. the third roller 611) being directed toward the outlet section 200. Thus, with reference to a transverse plane perpendicular to the advancement plane 6 (e.g. the transverse plane 5 as depicted in figure 2), the projections of the axis of the rollers 61 and 611 on said transverse plane are converging at a point below said advancement plane 6, while, with reference to a longitudinal plane perpendicular to the advancement plane 6 (e.g. the longitudinal plane 7 as depicted in figure 3 or 5), the projections of the axis of the rollers 61 and 611 on said longitudinal plane are diverging from each other below said advancement plane 6.

There is also to be noted that the means for supporting and advancing of the type described can also be used in furnaces in which the burners are arranged in a conventional manner or in any case, in a manner other than as described in the present document. Modules for heating furnaces and heating furnaces which comprise means for supporting and advancing as described above constitute a further aspect of the present invention.

Modules 1 for heating furnaces for metal bars 101, 102, 103, according to the present invention, are conveniently used for making furnaces that comprise one or more of said modules 1. These furnaces also constitute an aspect of the present invention.

With reference to figure 7, which schematically depicts the case of a molding line with hot cutting, furnace 100, in its most typical embodiment, generally comprises an inlet station of the bars, with direct inlet 301 (parallel to the advancement direction 4) or lateral inlet 302 (perpendicular to the advancement direction 4) of the bars, a plurality of heating modules 1 of the type described above and a hear cutting station 303. In the embodiment shown, furnace 100 comprises six modules 1, each of which has five pairs of burners and two pairs of rollers for supporting and advancing. Of course, different embodiments are possible, in which furnace 100 has a different number of modules 1, which in turn can have a different number of pairs of burners and pairs of rollers for supporting and advancing.

According to the description above, it has been seen that the module for heating furnaces for metal bars, according to the present invention, achieves its tasks and objects.

The module for heating furnaces for metal bars according to the invention finds convenient application mainly in molding lines with hot cutting of metal bars but the principle can be used in other industrial processes where the heating of bars is required, for example in heat treatment lines (hardening, cleaning, tempering and the like) of metal bars. Shape and size of the module for heating furnaces for metal bars according to the present invention can be the most varied according to the needs and requirements.

Finally, it should be noted that the module for heating furnaces for metal bars according to the present invention is relatively simple in construction and can be implemented using a relatively limited number of components.

Based on the description above, other features, modifications or improvements are possible and apparent to the man skilled in the art. Such features, modifications and improvements are therefore to be considered part of the present invention. In the practice, the materials used as well as sizes and shapes may be any, according to the requirements and the prior art.

Claims

1. Module (1) for heating furnaces (10) for metal bars (101, 102, 103), characterized in that it comprises:

- a combustion chamber (2) with longitudinal development along an advancement direction (4), delimited by a body of refractory material (3) and having an inlet section (20) and an outlet section (200);

- means for supporting and advancing said metal bars (101, 102, 103) along said advancement direction (4) from said inlet section (20) to said outlet section (200) on an advancement plane (6), arranged in said combustion chamber (2);

- at least a pair of burners (11,12) with a first (11) and a second (12) burner which face into said combustion chamber (2) above said advancement plane (6);

- the axes of said first (11) and second (12) burner being oriented tangentially with respect to said combustion chamber (2);

said first (11) and second (12) burner being both inclined in the direction of said inlet section (20) with respect to a transverse plane (5) perpendicular to said advancement direction (4).

2. Module (1) for heating furnaces (10) for metal bars (101, 102, 103), according to claim 1, characterized in that it comprises a plurality of pairs (11,12; 21,22; 31, 32, 41,42, 51,52) of first (11,21,31,41,51) and second (12,22,32,42,52) burners.

3. Module (1) for heating furnaces (10) for metal bars (101, 102, 103), according to claim 1 or 2, characterized in that said combustion chamber (2) has a substantially circular section.

4. Module (1) for heating furnaces (10) for metal bars (101, 102, 103), according to one or more of the preceding claims, characterized in that the angle formed by the axes of said first (11, 21,31,41,51) and second (12,22,32,42,52) burner is less than 180°.

5. Module (1) for heating furnaces (10) for metal bars (101, 102, 103), according to one or more of the preceding claims, characterized in that said first (11,21,31,41,51 ) and second (12,22,32,42,52) burner have the same inclination with respect to said transverse plane (5) perpendicular to said feed direction (4), the point of facing of said first (11,21,31, 41,51) and second (12,22,32,42,52) burner in said combustion chamber (2) lying on a same transverse plane (5) perpendicular to said feed direction (4).

6. Module (1) for heating furnaces (10) for metal bars (101, 102, 103), according to one or more of the preceding claims, characterized in that said means for supporting and advancing comprise a pair of rollers (61,62) with a first (61) and a second (62) roller which enter into said combustion chamber (2) above said advancement plane (6) and with their respective axes (610, 620) converging in a point below said advancement plane (6), the lateral surfaces (65,66) of said first (61) and second (62) roller defining a support surface for said metal bars (101, 102, 103).

7. Module (1) for heating furnaces (10) for metal bars (101, 102, 103), according to claim 6, characterized in that said first (61) and second (62) roller are disposed symmetrically with respect to a vertical longitudinal plane (7) passing through said feed direction (4) and perpendicular to said advancement plane (6).

8. Module (1) for heating furnaces (10) for metal bars (101, 102, 103), according to claim 6 or 7, characterized in that it comprises a plurality of pairs (61, 62; 71, 72) of first (61.71) and second (62, 72) rollers.

9. Module (1) for heating furnaces (10) for metal bars (101, 102, 103), characterized in that it comprises:

said means for supporting and advancing said metal bars (101, 102, 103) comprising a pair of rollers (61,62) with a first (61) and a second (62) roller which enter into said combustion chamber (2) above said advancement plane (6) and with their respective axes (610.620) converging in a point below said advancement plane (6), the lateral surfaces (65,66) of said first (61) and second (62) roller defining a support surface for said metal bars (101, 102, 103).

10. Module (1) for heating furnaces (10) for metal bars (101, 102, 103), according to claim 9, characterized in that said first (61) and second (62) roller are disposed symmetrically with respect to a vertical longitudinal plane (7) passing through said feed direction (4) and perpendicular to said advancement plane (6).

11. Module (1) for heating furnaces (10) for metal bars (101, 102, 103), according to claim 9 or 10, characterized in that one of said rollers of said pair of rollers (61,62) is inclined toward said inlet section (20) and the other one of said rollers of said pair of rollers (61,62) is inclined toward said outlet section (200)

12. Module (1) for heating furnaces (10) for metal bars (101, 102, 103), according to claim 11, characterized in that it comprises a second pair of rollers (611, 621) with a third (611) and a fourth (621) roller which enter into said combustion chamber (2) above said advancement plane (6), said third roller (611) being inclined in the opposite direction with respect to said first roller (61), said fourth roller (621) being inclined in the opposite direction with respect to said second roller (62).

13. Module (1) for heating furnaces (10) for metal bars (101, 102, 103), according to one or more of the preceding claims characterized in that said first (61) and second (62) roller impart a rotation movement of said metal bars (101, 102, 103) around their own axis.

14. Module (1) for heating furnaces (10) for metal bars (101, 102, 103), according to one or more of the preceding claims, characterized in that said first (11) and second (12) burner are a flameless burner and/or an oxygen-based burner.

15. Heating furnace (10) for metal bars (101, 102, 103), characterized in that it comprises one or more modules (1) according to one or more of the preceding claims.