(19)
(11) EP 1 757 886 A2

(12) EUROPEAN PATENT APPLICATION

(43) Date of publication:
28.02.2007 Bulletin 2007/09

(21) Application number: 06116460.4

(22) Date of filing: 30.06.2006
(51) International Patent Classification (IPC): 
F27B 9/24(2006.01)
F27B 9/38(2006.01)
F27D 3/06(2006.01)
 F27B 9/02(2006.01)
F27D 3/00(2006.01)
(84) Designated Contracting States:
AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IS IT LI LT LU LV MC NL PL PT RO SE SI SK TR
Designated Extension States:
AL BA HR MK YU

(30) Priority: 29.07.2005 IT BS20050094

(71) Applicant: ESTRAL S.P.A.
25025 MANERBIO BS (IT)

(72) Inventor:
  • Vincoli, Armando
    25100 Brescia (IT)

(74) Representative: Galassi, Alessandro 
Bugnion S.p.A., Via Dante, 17
25122 Brescia
25122 Brescia (IT)

   


(54) Heat treatment furnace for metal draw pieces


(57) Furnace (1) for the heat treatment of metal draw pieces (2) including a chamber (3), having an inlet (5) and an outlet (6), heating means (32) of the chamber (3), displacement means (20, 120) for transporting the draw pieces (2), in turn moved thanks to actuation means (25) and control means for adjusting the functioning of the furnace (1) itself. In particular, the displacement means (20, 120) displace the draw pieces (2) in a direction parallel to their longitudinal extension in the two directions.
In a first variation of the furnace, the displacement means (20) are suitable for transporting the draw pieces (2) between the inlet (5) and the outlet (6) of the chamber (3).
In a second variation, the displacement means (120) are externally operably associable with the inlet (5) and the outlet (6) of the furnace (1) for carrying out the introduction and the positioning of the draw pieces (2) on supporting means (131) housed within the furnace (1) and the withdrawal of the draw pieces (2) once the heat treatment is completed.


Description


[0001] The aim of the present invention is a furnace for the heat treatment of extruded metal draw pieces, or, more generally, metal elements extended in a longitudinal direction. Such kind of furnace is particularly used for the ageing process of aluminium draw pieces, to which the following description will expressly refer to, without losing for this reason the generality.

[0002] The ageing process of an aluminium draw piece usually takes place downstream of the extrusion, cooling, drawing and cutting steps.

[0003] It is well known that such process makes use of a furnace in which the draw pieces are introduced in metallic shelves, called baskets, in which they are arranged. Such baskets are therefore stacked so as to substantially assume the dimension of the furnace itself.

[0004] Specifically, the draw pieces are manually or automatically loaded in the baskets where they are spaced apart from each other by spacers which are preferably coated, for example with fabric, in order to avoid damages to the draw piece itself. Subsequently, the baskets are transported to the furnace inlet, introduced therein and withdrawn at the end of the residence time required for completing the heat treatment. However, the furnaces above described show some drawbacks.

[0005] Firstly, they require a high use of means, spaces, times and manpower for the operations of loading, unloading and transport of the baskets, with a consequent increase of the costs, above all the warehouse management and at the level of the production lead time. Secondly, during such operations, impacts, shakings and displacements of the draw pieces in the baskets frequently occur, which can give rise to more or less significant damages of the draw pieces themselves. Furthermore, because of the remarkable dimension and weight of the baskets, the introduction and extraction operations of the same from the furnace require a considerable time. This involves a significant loss of heat which requires additional operations of furnace heating, in order to bring back the temperature at the working values, which negatively affect the process times, the costs, particularly those of energy consumption and the productive yields. The energy consumption is made even more considerable because of the heat uselessly absorbed from the baskets themselves, as they are also made of metal materials, generally iron. Furthermore, the high quantity of heat exiting from the furnace during the introduction and extraction steps of the baskets produces uncomfortable working conditions for the operators. Some of these drawbacks, such as the high waste of (human and not) resources, the high chance of damages to the draw pieces during the loading and unloading operations of the furnace, the significant loss of heat and the dangerousness of the working environment for the operators are partly resolved thanks to a second technology for the heat treatment of metal draw pieces.

[0006] As it is known, such technology consists of an internally dynamic furnace in which the draw pieces are displaced by conveyor means from the inlet to the outlet of the furnace itself in a predetermined time and on multiple height levels. The transport of the draw pieces takes place perpendicularly with respect to their longitudinal extension, namely their length. In particular, the transport of the draw pieces is commonly carried out with the back-step or square pitch technology.

[0007] However, also this second kind of furnace involves some drawbacks. As the displacement of the draw pieces within the furnace occurs transversally to their length, the furnaces must have a correspondingly remarkable width and, therefore, a very strong and heavy structure. The width of the furnace is further limited from external bonds, such as the dimension of the productive spaces and the capacity of the transport means. Accordingly, the furnace is only able to contain draw pieces having a length lower than about 8000 mm. Furthermore, the heating plant is usually positioned within the upper surface of the furnace and is equipped with fans in order to make uniform the temperature of the chamber. This involves an increase at the energy consumption level, as the natural ascending convective movement of the hot air is not exploited. The known furnaces further show the drawback of not allowing the simultaneous treatment of draw pieces which require different temperatures, by negatively affecting the optimization of the productive process of the draw pieces.

[0008] In this situation, the technical task placed at the base of the present invention is to obviate to the drawbacks above mentioned.

[0009] Therefore, the aim of the invention is to provide a furnace for the heat treatment of metal draw pieces which requires a reduced use of resources (operators, displacement means, warehouses, energy, etc.). A further aim of the invention is to provide a furnace such that the damage risks to the draw pieces during the loading, unloading and internal displacement operations are reduced. It is still an aim of the invention to provide a furnace which allows to thermally treat draw pieces with a high length, compatibly with the plant spaces and the bonds imposed by the displacement of the draw pieces themselves. Moreover, an aim of the invention is to provide a furnace which has a reduced impact on the working conditions of the operators. Finally, an aim of the invention is to provide a furnace which has a rational and compact structure, which is easy to carry out and with a limited cost.

[0010] These and other aims, which will better result during the following description, are attained, according to the present invention, by a furnace for the heat treatment of metal draw pieces according to the appended claims.

[0011] Further features and advantages of the invention will result more apparent from the description of a preferred but non exclusive embodiment of the furnace, which is more detailed below with the aid of the following figures:
  • figure 1 shows a side view of a furnace chamber according to the invention in a first embodiment, wherein the furnace has a single chamber;
  • figure 1a shows an enlarged particular of figure 1;
  • figure 2 shows a section of the furnace of figure 1 taken according to the lines II-II;
  • figure 3 shows a front view of the furnace of figure 1;
  • figure 4 shows a side view of the chamber of a furnace according to the invention in a first embodiment, wherein the furnace has two thermally insulated chambers;
  • figure 5 shows a section of the furnace of figure 4 taken according to the lines V-V;
  • figure 6 shows a front view of the furnace of figure 4;
  • figure 7 shows a top view of the displacement means of a furnace according to the invention in a first embodiment;
  • figure 8 shows a front view of the transfer means of a furnace according to the invention in a first embodiment;
  • figure 8a shows a side view of the transfer means of figure 8;
  • figure 8b shows a top view of the transfer means of figure 8;
  • figure 9 shows a top view of a furnace according to the invention in a second embodiment, wherein the furnace is equipped with two thermally insulated chambers;
  • figure 10 shows a side view of the displacement means of the furnace of figure 9;
  • figure 11 shows a top view of the displacement means of the furnace of figure 9;
  • figure 12 shows a front view of the displacement means of the furnace of figure 9;
  • figure 13 shows a front view of the displacement means of the furnace of figure 9 wherein the displacement means are associated with the furnace chamber and are in a first working position;
  • figure 13a shows an enlarged particular of figure 13;
  • figure 14 shows a front view of the displacement means of the furnace of figure 9 wherein the displacement means are associated with the furnace chamber and are in a second working position;
  • figure 14a shows an enlarged particular of figure 14.


[0012] With reference to the mentioned figures, a furnace for the heat treatment of metal draw pieces and, particularly, a furnace for the ageing of aluminium draw pieces according to the invention is shown in the enclosed figures by numeral 1. The draw pieces are shown by numeral 2 and in the figures are represented in groups, more commonly called maps.

[0013] Such furnace 1 firstly includes a chamber 3, equipped with an inlet 5 and an outlet 6 for the introduction and the extraction of the draw pieces 2 and thermally insulated from the outside. In working conditions, such chamber 3 is heated by heating means 32 until it reaches an adequate temperature for the heat treatment process that one desires to carry out, which, in case of the aluminium ageing, corresponds to about 200°.

[0014] According to the invention, the heating means 32, which are preferably burners, are arranged in a lower portion 7 of the chamber 3. They can be installed in the flooring, as shown in figures 3 and 6, or be positioned substantially on its side, as shown in figures 13 and 14. In this way, the natural ascending convective movements of the hot air can be exploited with a saving at the energy consumption level. Furthermore, the heating means 32 can be advantageously equipped with blowing means 33 (figures 3, 6, 13 and 14) for uniformly dispensing the hot air within the chamber 3, so as to avoid any differences, also minimal, in the draw pieces 2 simultaneously treated.

[0015] In order to reduce the problem of heat dispersion, particularly significant during the loading and unloading steps of the draw pieces 2 in the furnace 1, the inlet 5 and the outlet 6 of the chamber 3 can be advantageously equipped with closing means (not shown in the figures) suitable for thermally insulating the chamber 3 itself from the outside during the heat treatment process of the draw pieces. They can include, for example, a door equipped with springs or an automatically operated gate.

[0016] According to the invention, the furnace 1 further includes displacement means 20, 120, suitable for displacing the metal draw pieces 2, on which actuation means 25 are active, in order to impart them the movement. It has to be specified that in the enclosed figures, the actuation means 25 are only represented for the first embodiment of the invention shown in the figures from 1 to 8b. Moreover, such actuation means 25 generally include electric motors 26 and are connected to the control means which drive the functioning thereof.

[0017] In particular, the displacement means 20, 120 are characterized in that they displace the draw pieces 2 in a direction parallel to their longitudinal extension, namely their length. The draw pieces 2, in fact, are preferably positioned on such displacement means 20, 120 so as to have the longitudinal main axes extending according the longitudinal extension direction of the furnace 1 itself. This makes possible, when allowed by the dimensions of the available spaces, to treat draw pieces 2 having a theoretical length up to 48 m (and a practical length up to 24 m).

[0018] A further particular which characterizes the displacement means 20, 120 is that they are operably active directly on the draw pieces 2, or rather on the maps of draw pieces, as it can be observed in the enclosed figures.

[0019] A further component of a furnace 1 according to the invention, in fact, are the control means (not shown) which are operably active substantially on the heating means 32 and the actuation means 25 and, advantageously, also the closing means, for example in case of an automatic gate. Such control means manage the heat treatment process carried out in all its parts and include an electronic card equipped with a microprocessor, on which a software and interface means for setting the operating parameters from the outside are implemented. It is possible to set, for example, the temperature at which the chamber 3 of the furnace 1 is to be brought and maintained by acting on the heating means 32 or the residence time of the draw pieces 2 within the furnace 1. To the control means, furthermore, temperature sensors placed within the chamber 3 can advantageously be connected in order to detect and, accordingly, adjust the temperature of the chamber 3 itself.

[0020] In a preferred embodiment of the invention, the furnace 1 is characterized by a chamber 3 which includes at least two secondary chambers 4 thermally insulated therebetween and having inlets 8 and outlets 9, heating means 32, displacement means 20, 120 and actuation means 25 for thermally treat the draw pieces 2 at different temperatures, as shown by the figures 4, 5, 6 and 9. Preferably, it is the chamber 3 itself of the furnace 1 which results subdivided in two secondary chambers 4 through an insulating wall 10 (figures 5, 6 and 9). The two chambers 4 are generally carried out such that they have the inlets 8 and the outlets 9 respectively flanked, in order to rationalize and simplify the introduction and extraction steps of the draw pieces 2 from the furnace 1 (figure 5).

[0021] In this case, the two chambers 4 are separately managed by the control means, both at the temperature level and the residence times of the draw pieces 2 within the furnace 1.

[0022] Alternatively, the heat treatment of draw pieces 2 which require different temperatures can be carried out by using two furnaces 1 placed side by side in a longitudinal direction.

[0023] The invention thus conceived is susceptible of various modifications and variants, all falling in the ambit of the inventive concept.

[0024] In a first variant of the furnace according to the invention, the displacement means 20 are suitable for transporting the draw pieces 2 from the inlet 5 to the outlet 6 of the chamber 3 in a predetermined and specific time for each map of draw pieces 2, equal to that required for completing the ageing process.

[0025] Preferably, such displacement means 20 include rollers 21, on which the actuation means 25 are operative, placed between the inlet 5 and the outlet 6 of the chamber 3 of the furnace 1 and positioned such that they have main axes 22 parallel therebetween and perpendicular to the displacement direction of the draw pieces 2.

[0026] In a preferred embodiment of the invention, a motor 26 for each group of rollers 21 is foreseen, such that each of these group of rollers 21 can be operated in an independent way relative to the others, with remarkable advantages (shown below) at the flexibility level of the heat treatment process carried out. Alternatively, a separate motor 26 for each roller 21 could be foreseen, in order to render the movement of each roller 21 independent from each other. However, this latter solution involves greater costs and greater execution difficulties.

[0027] Furthermore, the actuation means 25 allow to displace the rollers 21 in both directions, allowing the operator which controls the furnace 1 to correct possible errors in the setting of the functioning parameters or to improve the filling of the furnace 1 through the control means. In fact, the displacement means 20 are reversibly mounted such that the motion direction of the draw pieces 2 can be inverted.

[0028] Alternatively to the rollers 21, the displacement means 20 can also include conveyor belts (alternative not shown). In this case, it is very important to use bored belts for ensuring a proper heat exchange between the draw pieces 2 and the chamber 3 during the residence of the draw pieces 2 themselves inside the furnace 1.

[0029] A furnace 1 according to this first variant of the invention further includes transfer means 30 for the draw pieces 2, operably connected with the inlet 5 of the chamber 3 of the furnace 1 for positioning the draw pieces 2 on the displacement means 20 and at the outlet 6 of the chamber 3 for collecting the draw pieces 2 from the displacement means 20 at the end of the heat treatment. In figure 8, the transfer means 30 placed at the furnace inlet are shown. Such means 30 are suitable for displacing the draw pieces 2 according to an advancing direction 34 towards the inlet 5 of the furnace 1, thanks to advancing means 37 which, as it can be seen in figure 8b, preferably consist of rollers. In particular, the draw pieces 2 are positioned on the displacement means 20 by the transfer means 30 such that the main longitudinal axes are substantially parallel therebetween and extending according to the longitudinal extension direction of the furnace 1 itself.

[0030] The parts of the displacement means 20 and the transfer means 30 which mainly come into contact with the draw pieces 2 having a high temperature are preferably coated with a thermally insulating material and structured so as to reduce the possibility of damage of the draw pieces 2 themselves during the displacement, for example with some fabric.

[0031] The displacement means 20 can be arranged on a single height level 23 but, in a preferred embodiment of the invention, they are arranged on a plurality of different height levels 23 for defining a plurality of different displacement pathways 24 for the draw pieces 2 within the furnace 1 (figures 1, 2, 4 and 6).

[0032] In this case, therefore, the transfer means 30 also include lifts 31 for displacing the draw pieces 2 on different height levels 23 in which the displacement means 20 are arranged. As it can be observed by figure 8, in fact, the transfer means 30 are suitable for displacing the draw pieces 2, in addition to an advancing direction 34, also in a upward direction 35 and a downward direction 36.

[0033] Specifically, for example, the furnace 1 can be structured on a multiplicity of height levels 23 accessible by a first lift 31 for the loading of the draw pieces 2 and by a second lift 31 which provides for the extraction.

[0034] Peculiar characteristic of the displacement means 20 arranged on a plurality of height levels 23 is the movement independence between the aforesaid levels 23, allowed for example by the movement independence of the different rollers 21 and the flexibility of the control means. In this way, in the same furnace 1 it is possible to treat draw pieces 2 which require different residence times, for example, because of a different length or different section dimensions.

[0035] More particularly, each kind of draw piece 2, characterized for example by a particular length and dimensions of the section is arranged on displacement means 20 placed at a particular height level 23 for following a displacement within the furnace 1 adjusted by a particular timing. Depending on the parameters set by the operator, which can also undergo corrections during the heat treatment, the control means operate the actuation means 25 in a controlled way until the draw pieces 2 have completed the treatment. At this point, the transfer means 30, also driven by the control means, withdraw the draw pieces 2 in order to direct them toward the following steps of their productive process and the control means provide, if necessary, to adjust the arrangement of the draw pieces 2 remained in the furnace 1, for improving the filling thereof and therefore the yield of the process itself. In a second embodiment of a furnace 1 according to the invention, the displacement means 120 are externally operably associable in correspondence with the inlet 5 of the furnace 1 for carrying out the introduction and the positioning of the draw pieces 2 in the furnace 1 and externally in correspondence with the outlet 6, in order to carry out the withdrawal of the draw pieces 2 from the furnace 1. Advantageously, the inlet 5 and the outlet 6 of the chamber 3 can also be corresponding. In this case, the displacement means 120 are externally operably associable in correspondence with the inlet 5 of the chamber 3, for carrying out both the introduction and the withdrawal of the draw pieces 2.

[0036] Furthermore, the displacement means 120 are movable in a direction substantially transverse relative to the furnace 1 for serving the two secondary chambers 4 of a same furnace 1 or two different furnaces 1 placed side by side in a longitudinal direction. As it is shown in figure 12, the displacement means 120 can advantageously be equipped with wheels 127 associated with a lower portion 128 thereof, preferably suitable for transversally sliding with respect to the furnace 1 on rails associated with the flooring on which they are supported.

[0037] In particular, therefore, in the first case each furnace 1 can be equipped with two displacement means 120, one placed at the inlet 5 of the chamber 3 and responsible for the introduction of the draw pieces 2 and one placed in correspondence with the outlet 6 for the withdrawal. In the second case, on the contrary, a single displacement means 120 can serve one or more furnaces 1.

[0038] According to the second embodiment of the invention, the furnace 1 includes means 131 for supporting the draw pieces 2 in its interior during the heat treatment. As it is shown by the figures 9, 13 and 14, such means 131 are advantageously associated in an integral way to the chamber 3 and include a plurality of supporting bars 132 substantially parallel therebetweeen, so as to form a kind of comb, associated with a first wall 137 longitudinal to the chamber 3 and defining a plurality of first interspaces 134 between the different supporting bars 132.

[0039] In a preferred embodiment of the invention, the different supporting means 131, namely the various groups of supporting bars 132 are arranged on a plurality of different height levels 133 for defining a plurality of different heat treatment pathways 135 for the draw pieces 2 within the furnace 1.

[0040] Furthermore, the chamber 3 includes a plurality of guides 136 associated with a second longitudinal wall 138 thereof, opposite to the first one 137, respectively arranged in correspondence with the different height levels 133 defined by the supporting means 131. Preferably, such guides 136 are longitudinally extending, in parallel to the displacement direction of the draw pieces, along at least a portion of the second longitudinal wall 138 of the chamber 3.

[0041] Always according to the invention, the displacement means 120 include means 121 for the introduction and the withdrawal of the draw pieces 2 which, in turn, include a plurality of supporting elements 122 mounted on a support element 123. Such supporting elements 122 are substantially parallel therebetween and arranged so as to define a plurality of second interspaces 124, also assuming a comb-like conformation, in order to interact with the plurality of supporting bars 132 at a determined height level 133 for positioning the draw pieces 2 on the supporting bars 132 and collect them from these bars 132 when the heat treatment is ended.

[0042] More particularly, the supporting element 123 to which the supporting element 122 are associated is movable according to a longitudinal direction, shown in figure by numeral 126, with respect to the furnace 1, and in this way the supporting element 122 result movable between a back position, in which all the supporting elements 122 are outside the furnace 1, and an advanced position, in which the supporting elements 122 are, at least partly, inside the furnace 1. Preferably, as it can be observed by the figures 10, 13 and 14, the supporting element 123 is movable between the two mentioned positions, by engaging itself in the lower portion 136a of the guide 136 placed in correspondence with a determined height level 133 and sliding, through small wheels 129, on the upper portion 136b of the underlying guide 136.

[0043] Furthermore, the displacement means 120 are movable in a vertical direction 125 (figure 10) through the actuation means 25 (not shown in the figures relating to the second embodiment) so as to ensure that they reach the different height levels 133 in order to engage themselves and slide on the corresponding guide 136 during their movement from the back position to the advanced position, or vice versa.

[0044] Moreover, the supporting elements 122 are jointly movable relative to the supporting element 123, in a reversible way, from a first position in which such elements 122 are above the supporting bars 132 which define a determined height level 133 (figure 13a), to a second position in which the supporting element 122 are below these bars 132 (figure 14a). In particular, the supporting element 122 are movable from the first to the second position for the introduction of the draw pieces 2 on the supporting bars 132 and from the second to the first position for the withdrawal of the draw pieces 2 from the supporting bars 132. The supporting elements 122 are movable from the first to the second position or from the second to the first position through an intermediate position in which at least one of the supporting elements 122 is inserted in one of the first interspaces 134 defined by the supporting bars 132 and, mutually, at least a supporting bar 132 is inserted in one of the second interspaces 124 defined by the supporting elements 122. More particularly, therefore, the two combs consisting of the supporting bars 132 and the supporting elements 122 are intersected, at least partly, in the respective interspaces 134, 124 and, in this way, the supporting elements 122 can release or collect from the supporting bars 132 the different draw pieces 2.

[0045] Each of the four kinds of movement of the displacement means 120 described, namely the movement in the transverse direction relative to the furnace 1, the movement between the advanced position and the back one and in a vertical direction of the introduction and withdrawal means 121 and the movement between the first and the second position of the supporting elements 122 is allowed by the actuation means 25 and adjusted through the control means.

[0046] By way of example, the displacement means 120, shown in detail in the figures 10, 11 and 12, have approximately a longitudinal extension of 30 m and a height of 9 m.

[0047] Preferably, the supporting means 131 and the introduction and withdrawal means 121 can be coated with materials which absorb the impacts and which are resistant to the high temperatures, in order to reduce the damages risk to the draw pieces 2 during their displacement and for reducing the need of maintenance due to the wear of the components.

[0048] While a furnace 1 according to the first embodiment is completely dynamic, as the draw pieces 2 are displaced during the heat treatment, a furnace 1 according to this second embodiment can be both static and dynamic, depending on the use. In fact, although the draw pieces 2 are housed within the furnace 1 on a fixed structure and integral with the chamber 3, for each height level 133, through the displacement means 120, it is possible to extract part of the draw pieces 2 from the furnace 1, place again the draw pieces 2 within the furnace 1 or introduce the draw pieces 2 upon the supporting bars 132 which are remained empty. Preferably, a furnace according to the second embodiment is made dynamic by using two displacement means 120 respectively dedicated to the introduction and the withdrawal of the draw pieces, as the software implemented on the control means in case of a single displacement means, 120 which plays the double function of introduction and withdrawal, would be too complicated.

[0049] Indeed, the materials used, as well as the dimensions, could be any one, depending on the requirements.

[0050] Furthermore, all the details are replaceable with other technically equivalent elements.

[0051] The invention attains important advantages.

[0052] Firstly, a furnace for the heat treatment of metal draw pieces according to the invention remarkably reduces the problem of heat dispersion, thanks to the automation which has allowed to speed up especially the steps of loading and unloading of the draw pieces from the furnace, the use of closing means on the inlets and outlets of the chambers, the use of a structure on multiple height levels and the transport parallel to the longitudinal extension of the draw pieces themselves which allow to dimensionally reduce the inlet and outlet areas. This positively affects the costs, especially those of energy consumption, the times and, therefore, the productive yields. The reduction of the energy waste is also promoted by the positioning of the heating means in a lower surface of the chamber, so as to exploit the ascending convective movement which characterizes the hot air by nature, contrary to what happens in the furnaces of the known type, wherein the heating means are arranged in the upper surface of the furnace.

[0053] Moreover, the high automation level which characterizes the invention with respect to the prior technologies and the pathways on the created multiple height levels allow to reduce the use of resources and spaces with benefits at the costs level, particularly those of manpower and warehouse, and to increase the productivity not only of the heat treatment process per se but also of the whole production process of the draw pieces.

[0054] The reduction of the loss of heat, the automation and the total management of the plant through the control means have also allowed the improvement of the working conditions of the operators and the reduction of the damage possibility of the draw pieces during the heat treatment.

[0055] A further advantage is that the displacement of the draw pieces parallelly to their longitudinal extension and their positioning in the furnace with the main axis lying parallelly to the longitudinal extension of the furnace have allowed to lighten the structure of the furnace itself, above all in the width, and to carry out the heat treatment step also upstream of the cutting step, since, compatibly with the spaces dimension and the capacity of the transfer means, the furnace can contain draw pieces having a theoretical length up to 48 mm.

[0056] Furthermore, the embodiments of the invention which foresee a furnace with multiple secondary chambers join the advantage of being able to simultaneously thermally treat draw pieces having different requirements of temperature, with a remarkable saving on the production times and an increase of the rationality and the effectiveness of the productive process itself. Again, a single furnace with large dimensions with multiple chambers operating at different temperatures allows to greatly exploit the scale economies with respect to multiple furnaces with lower dimensions, by inducing some benefits, such as the reduction of the energy consumption, a lower heat dispersion and a lower use of human resources.

[0057] The furnace subject of the invention, in both the embodiments, shows the additional advantage of allowing the heat treatment of draw pieces which require different residence times in the furnace, with important advantages on the optimization and the effectiveness of the productive process, above all thanks to the remote management of the functioning of the furnace itself thanks to the control means.

[0058] The second embodiment, furthermore, shows an important advantage at the maintenance level for the wear of the furnace components, as the components (bearings, chains, etc.) working at high temperature, are remarkably reduced, using fixed supporting means instead of the rollers or the conveyor belts used in the first embodiment.


Claims

1. Furnace (1) for the heat treatment of metal draw pieces (2) including: a chamber (3) having an inlet (5) and an outlet (6) and thermally insulated from the outside, heating means (32) of said chamber (3), displacement means (20, 120) for displacing said metal draw pieces (2), actuation means (25) operably active on said displacement means (20, 120) for imparting the movement to said displacement means (20, 120) and control means operably active on said heating means (32) and said actuation means (25); characterized in that said displacement means (20, 120) are suitable for displacing said draw pieces (2) in a direction parallel to the longitudinal extension of said draw pieces (2) .
 
2. Furnace (1) according to the preceding claim, characterized in that said displacement means (20, 120) are operably active directly on said metal draw pieces (2).
 
3. Furnace (1) according to any one of the preceding claims, characterized in that said heating means (32) are operably active on a lower portion (7) of said furnace (1).
 
4. Furnace (1) according to any one of the preceding claims, characterized in that said heating means (32) are equipped with blowing means (33) for uniformly dispensing hot air within said chamber (3).
 
5. Furnace (1) according to any one of the preceding claims, characterized in that said actuation means (25) include electric motors (26).
 
6. Furnace (1) according to any one of the preceding claims, characterized in that said control means include an electronic card equipped with microprocessors and interface means for setting functioning parameters from the outside.
 
7. Furnace (1) according to any one of the preceding claims, characterized in that it further includes means for closing said inlet (5) and said outlet (6) of said chamber (3) during the heat treatment of said draw pieces (2), operably connected with said control means, for reducing the loss of heat in said chamber.
 
8. Furnace (1) according to any one of the preceding claims, characterized in that said chamber (3) includes at least two secondary chambers (4) thermally insulated therebetween and equipped with inlets (8) and outlets (9), heating means (32), displacement means (20, 120) and actuation means (25) for thermally treating said draw pieces (2) at different temperatures.
 
9. Furnace (1) according to any one of the preceding claims, characterized in that said displacement means (20) are placed between said inlet (5) and said outlet (9) of said chamber (3).
 
10. Furnace (1) according to any one of the preceding claims, characterized in that said displacement means (20) are reversible for allowing the reversal of the motion direction of said draw pieces (2) in said furnace (1).
 
11. Furnace (1) according to any one of the preceding claims, characterized in that said displacement means (20) include rollers (21) positioned between said inlet (5) and said outlet (6) of said chamber (3) with longitudinal main axes (22) parallel therebetween and perpendicular to said displacement direction of said draw pieces (2).
 
12. Furnace (1) according to claim 11 when depending from claim 5, characterized in that each of said rollers (21) is associated with an own electric motor (26) for being operable independently from the remaining rollers (21).
 
13. Furnace (1) according to any one of the claims 1 to 10, characterized in that said displacement means (20) include bored conveyor belts for allowing the heat exchange between said chamber (3) and said draw pieces (2) during the displacement of said draw pieces (2) .
 
14. Furnace (1) according to any one of the preceding claims, characterized in that it includes displacement means (20) arranged on a plurality of different height levels (23) for defining a plurality of displacement pathways (24) of said draw pieces (2) in said furnace (1) .
 
15. Furnace (1) according to claim 14, characterized in that it further includes transfer means (30) of said draw pieces (2), connected with said control means, operably associable to said inlet (5) of said chamber (3) for positioning said draw pieces (2) on said displacement means (20) and to said outlet (6) of said chamber (3) for taking said draw pieces (2) from said displacement means (20), equipped with lifts (31) suitable for displacing said draw pieces (2) in correspondence with said height levels (23) on which said displacement means (20) are arranged.
 
16. Furnace (1) according to any one of the claims 1 to 8, characterized in that said displacement means (120) are externally operably associable in correspondence with said inlet (5) of said furnace (1) for carrying out the introduction and the positioning of said draw pieces (2) in said furnace (1) and externally operably associable in correspondence with said outlet (6) of said furnace (1) for carrying out the withdrawal of said draw pieces (2) from said furnace (1).
 
17. Furnace (1) according to claim 16, characterized in that said inlet (5) and said outlet (6) of said chamber (3) are corresponding and that said displacement means (120) are externally operably associable in correspondence with said inlet (5) of said furnace (1) for carrying out both the introduction and the withdrawal of said draw pieces (2) in said furnace (1).
 
18. Furnace (1) according to any one of the claims 1 to 8 and 16 to 17 when depending from claim 8, characterized in that said displacement means (120) are movable in a direction substantially transverse relative to said furnace (1) for carrying out the introduction and/or the withdrawal of said draw pieces (2) from said at least two secondary chambers (4) of said furnace (1) or from at least two of said furnaces (1) placed side by side in a longitudinal direction.
 
19. Furnace (1) according to any one of the claims 1 to 9 or 16 to 18, characterized in that it further includes means (131) for supporting said draw pieces (2) in said furnace (1) during the heat treatment integrally associated with said chamber (3).
 
20. Furnace (1) according to claim 19, characterized in that said supporting means (131) include a plurality of supporting bars (132) substantially parallel therebetween, associated with a first longitudinal wall (137) of said chamber (3) and arranged so as to define a plurality of first interspaces (134) between said supporting bars (132).
 
21. Furnace (1) according to claims 19 or 20, characterized in that said supporting means (131) are arranged on a plurality of different height levels (133) for defining a plurality of different pathways (135) of heat treatment for said draw pieces (2) in said furnace.
 
22. Furnace (1) according to any one of the claims 1 to 9 or 16 to 21, characterized in that said displacement means (120) include introduction and withdrawal means (121) of said draw pieces (2) in said furnace (1) which are movable between a back position outside said furnace (1) and an advanced position in which they are at least partly within said furnace (1).
 
23. Furnace (1) according to claim 22 when depending from any one of the claims 19 to 21, characterized in that said introduction and withdrawal means (121) include a plurality of supporting elements (122) mounted on a supporting element (123) longitudinally movable relative to said furnace (1), said supporting elements (122) being substantially parallel therebetween and arranged so as to define a plurality of second interspaces (124) between said supporting elements (122) suitable for interacting with said plurality of supporting bars (132) for positioning said draw pieces (2) on said plurality of supporting bars (132) and collecting said draw pieces (2) from said plurality of supporting bars (132) once the heat treatment is ended.
 
24. Furnace (1) according to any one of the claims 21 to 23, characterized in that said chamber (3) includes a plurality of guides (136) associated with a second longitudinal wall (138) of said chamber (3), opposite to said first longitudinal wall (137), respectively arranged in correspondence with said height levels (133) so as to longitudinally extend themselves, parallelly to said displacement direction of said draw pieces (2), along at least a portion of said second longitudinal wall (138) of said chamber (3).
 
25. Furnace (1) according to claim 24, characterized in that said introduction and withdrawal means (121) are displaced in a vertical direction (125) from said actuation means (25) so as to reach one of said height levels (133) for engaging themselves and sliding on the corresponding guide (136).
 
26. Furnace (1) according to any one of the claims 23 to 25 when depending from the claim 21, characterized in that said plurality of supporting elements (122) is reversibly movable with respect to said supporting element (123) from a first position, in which said plurality of supporting elements (122) is above said plurality of supporting bars (132) at a determined height level (133), to a second position, in which said plurality of supporting elements (122) is below said plurality of supporting bars (132) defining said determined height level (133), said plurality of supporting elements (122) being movable from said first to said second position for the introduction of said draw pieces (2) on said plurality of supporting bars (132) and from said second to said first position for the withdrawal of said draw pieces (2) from said plurality of supporting bars (132).
 
27. Furnace (1) according to claim 26, characterized in that said plurality of supporting elements (122) is movable between said first to said second position or from said second to said first position through an intermediate position in which at least one of said supporting elements (122) is inserted in one of said first interspaces (134) defined by said plurality of supporting bars (132).
 
28. Furnace (1) according to any one of the preceding claims, characterized in that it is suitable for the ageing heat treatment of aluminium draw pieces (2).
 
29. Plant for the heat treatment of metal draw pieces (2) characterized in that it includes a furnace (1) according to any one of the preceding claims.
 




Drawing