ITPN20010007A1 - HEAT TREATMENT OVEN OF METAL PROFILES OF VARIOUS KINDS - Google Patents

Description

"OVEN FOR THE HEAT TREATMENT OF METAL SECTIONS OF VARIOUS KIND"

The invention relates to a heat treatment oven for metal profiles of various kinds, made by extrusion and cut and stretched to the required lengths in a transfer and ironing plant arranged upstream of the oven itself, this oven being able to allow the treatment of the metal sections with carrying out of the operating phases in a completely automated manner, with considerably reduced residence times in the furnace and with a high production yield and less use of personnel for the management of the furnace.

There are known heat treatment furnaces for metal sections of various kinds, and particularly of aluminum sections, which are extruded, cut and stretched to the required measurements in a transfer and ironing plant arranged upstream of the furnace itself. These metal profiles are combined in maps and transported to the end of the plant by suitable conveyor means provided in the plant itself, and subsequently they are loaded manually and / or automatically into baskets, with adequate containment capacity (of the order of about 70 -80 pieces each). and these baskets are then introduced longitudinally into the interior of the furnace stacked on the other, with the various sections in mutual contact, and kept in the furnace for sufficient residence times to subject the various sections to the required heat treatment, generally of about 6-8 hours, after the baskets are taken out of the oven and the profiles taken for their use.

The ovens thus structured, however, have a series of drawbacks.

First of all, in fact, the use of the baskets to contain the various metal profiles requires a series of complex and laborious operations, with the continuous presence of personnel, to load the baskets with these profiles first, then to introduce the baskets into the oven. and finally to extract them from the oven and unload the treated sections.

Furthermore, in these circumstances it is not possible to prevent the profiles from being stacked in the baskets incorrectly, and from moving or being subject to shaking during the movement of the baskets, and consequently from being dented or damaged on the surface to different degrees.

A further drawback of this profile transport system consists in the fact that to allow access to the oven during the operations of inserting and extracting the baskets with the profiles relative to it, the temporary opening of the doors of the area is required. inlet and outlet of the furnace itself, with consequent dispersion of heat towards the outside and temporary decrease of the internal temperature of the furnace, and the need for additional heating to bring this temperature back to the required values.

In this way, this additional heating inevitably leads to higher energy requirements, longer cycle times, and lower oven yields.

»The present invention aims to eliminate the drawbacks described in a heat treatment furnace for metal J profiles, by using a furnace made in such a way as to allow the completely automated carrying out of all the loading and unloading operations of the profiles, with criteria different from those known so far, and such as to rationalize the heat treatment of the materials of the sections with reduced energy consumption, less use of personnel and greater production yield.

This oven is made with the construction characteristics substantially described, with particular reference to the accompanying drawings in which:

- fig. 1 shows a schematic front view of an oven according to the invention;

- fig. 2 shows a side schematic view of the oven of fig. 1, sectioned along the A-A line;

- fig. 3 shows a side view of the drive mechanism employed in the present furnace;

- fig. 4 shows a front view of the operating mechanism of fig. 3, moved to a first operative position;

- fig. 5 shows a front view of the actuation mechanism of fig. 3, moved to a second position

operational.

In the aforementioned figures, an oven 6 according to the invention is schematically shown, provided for the heat treatment of extruded metal sections, preferably aluminum sections, transferred by suitable conveyor means from an upstream section extrusion, cutting and ironing plant. of the oven itself.

As can be seen particularly in figs. 1 and 2, this heat treatment furnace substantially comprises a closed metal box-like structure 7 of large dimensions, delimiting an internal chamber 8 with a large capacity for containing metal sections, in which the air is heated to a certain operating temperature, preferably of 250 ° C max., by means of generators consisting of methane gas burners of the radiant tube type (not indicated), and in which the hot air is circulated by means of a series of fans (not indicated) suitably arranged outside of the oven, and connected through unions with the internal chamber 8 so as to distribute the hot air uniformly within this internal chamber.

The box-like structure 7 of the furnace is arranged near the terminal end of the conveyor means (not shown) and is structured, as will be described, to receive the metal sections transferred by these conveyor means and suitably arranged together in groups or maps, and for introduce these sections into the internal chamber 8, conveying them through it and keeping them there for the time necessary to subject them to the required heat treatment, and finally to unload the treated sections from the furnace, and all these operations are carried out automatically as will be described.

Moreover, this box-like structure 7 of the furnace extends for its width in the same direction as the conveyor means, and in correspondence with the terminal end of the same, so as to be able to receive the sections transported by said conveyor means, and introduce them inside. of the furnace, and also extends for its length orthogonally to said conveyor means, so as to transport all the sections in this direction for the entire duration of their heat treatment, from the introduction side in correspondence with said terminal end to the drain located in the opposite position.

Furthermore, as can be seen from the aforementioned figures, the present furnace substantially comprises a loading unit, arranged at the inlet of the furnace, and provided for the introduction into the internal chamber of the furnace 8 of the sections assembled in maps, a transfer unit 13 of the maps of sections, arranged in the internal chamber 8 and provided for selectively transferring the profile maps along the entire length of said internal chamber, and an unloading unit arranged at the exit of the furnace and provided for unloading from the furnace the profile maps transferred through the transfer unit 13 and heat treated in the internal chamber 8.

All the actuation mechanisms of the various groups are automatically controlled and suitably protected, to reduce the risk of accidents, and are controlled through corresponding P.L.C. interfaced with a centralized system with P.L.C. and powered by a general electrical panel (not indicated), complete with all the components for powering the various control circuits of the mentioned groups.

The conformation and operation of the various groups for loading, transferring and unloading the sections are now described, always referring to both the aforesaid figures and also to figs. 3-5.

The loading and unloading units (not indicated) are made identical to each other, in the form of a respective lift with motorized rollers (not indicated), supported by a corresponding rigid structure in electro-welded steel, with vertical extension (not indicated), fixed to it externally to the furnace, said elevators being commanded to move simultaneously, with opposite vertical directions of movement, and are adapted to support the profile maps to determine the lifting of said profiles from the level of the conveyor means to different heights, in order to the functions that will be described, and the other the lowering of the profiles from the height respectively reached to the level of further conveyor means (not indicated), located on the unloading side of the furnace and provided for transferring all the profiles to the packaging area heat treated.

These elevators are automatically controlled with slow movements through electronic control circuits and electric gearmotors and are associated with corresponding openings of the furnace, closed by respective automatically opening doors 12 and 14, to make the sections pass through the openings themselves during the operations of loading and unloading, and at the end of these operations the doors close on the openings, thus minimizing the dispersion of hot air from the internal chamber of the oven towards the outside.

Furthermore, the elevators are associated with limit switches for detecting the position of the profile maps, which enable the control circuits, with consequent movement of the elevators themselves and their displacement to the required height level, in the presence of sections to be treated transferred to the relative lift, and said sensors also disable these control circuits and therefore stop the movement of the lifts, in the absence of sections.

In turn, the transfer unit 13 consists of a plurality of horizontal rectilinear shelves 21, identical and superimposed on each other at different height levels, for the entire extension of the furnace, which are anchored to the base 10 of the furnace by means of a structure in electro-welded steel and connected to each other by bolts. These shelves, of the fixed type, are divided transversely to the oven in a series of single sliding paths 22 separated from each other, which extend from the inlet to the outlet of the kiln, in the present example consisting of 6 paths, whose function is that to transport the sections from the entrance to the exit of the kiln as will be described, each of which is structured at the top with a series of fixed bars or idle rotating rollers (not indicated) for their entire extension, with the exception of the ends of deti. sliding paths which are structured with motorized rollers 1S, to respectively allow the automatic arrangement on the sliding paths of the sections transported by the lift of the furnace entrance, and the unloading of the sections from the sliding paths with the lift of the exit of the oven.

These platforms are formed by suitably sized profiles joined together, the upper surface of which is covered with a layer of heat resistant material, preferably of the Kevlar type, which in addition to resisting high temperatures protects the profiles from any dents along the entire length. respective scroll path.

The transfer unit 13, moreover, consists of a plurality of horizontal rectilinear platforms 24, of the mobile type, cooperating with the fixed platforms and movable with respect to the latter in the manner and for the purpose that will be described.

These mobile platforms 24 are provided in each sliding path, for the entire longitudinal extension of the paths themselves, and are preferably adaptable to the fixed platforms, as visible in figs. 4 and 3, said movable platforms being structured at the top with movable bars 23, arranged longitudinally to the oven, parallel to the fixed bars or idle rotating rollers of the fixed platforms, and also being covered by a layer of heat-resistant material, identical to that of the platforms fixed.

The purpose of the movable platforms 24 is to carry out the transfer by steps of the sections along the different sliding paths 22 parallel to each other, with a series of movements designed to cause the lifting and longitudinal translation of these sections in succession, and then the lowering of this movable platform and the consequent deposition of the sections, and the return of the movable platform moved to the initial position, with a translation movement which is the reverse of the previous one. In this way, the arrangement of these profiles on the consecutive area allows to free the support surface of the previous area, thus making it available for the arrangement of the subsequent profiles, a condition in which the profiles are progressively transferred towards the outlet.

In particular, these movements are performed continuously and automatically with calculated speeds so that each profile map introduced into the furnace takes the same time from the moment of entry to that of exit with respect to the furnace, thus being subjected to the heat treatment of aging with the same conditions.

In particular, in the case of aluminum profiles this treatment normally takes place over a period of 3 hours.

To determine movements of this kind, a possible drive mechanism suitable for the purpose is described by way of non-limiting example.

This mechanism is substantially constituted by a series of elongated shafts 26 with limited rotation, housed transversely in the internal chamber 8 of the furnace, parallel to each other, and rotated by a control unit 27 arranged outside the furnace, in correspondence with one of the sides of the oven, and provided to control all the movements of the mobile platforms 24 with control by means of independent P.L.C.electric circuits, interfaced with further P.L.C.electric circuits. control of the furnace heating generators and with the centralized system with P.L.C.

Each shaft 26 supports both a first series of lever eccentrics 28 and a second series of lever eccentrics 29, provided in correspondence with the respective mobile platforms 24 and fixed 21, of which each eccentric 28 of the first series is axially spaced from each eccentric 29 of the second series and is fixed with one end to the rotating shaft 26 and with the other end it supports a pressure roller 30, constantly pressed against the lower surface of the corresponding mobile platform 24 (or fixed to the latter in a jointed way ), and of which each eccentric 29 of the second series is fixed with one end to the rotating shaft 26 and is articulated with its other end in a bracket 31 fixed to the lower surface of the corresponding fixed platform 21, and these eccentrics are suitably offset angularly from each other, so that the actuation of the shaft in a direction of rotation first determines the gradual lifting of the mobile platform, c he is initially moved to its lowered rest position in which it is housed in the relative fixed platform 21, up to its operating position shown in fig. 4 in which it is completely raised from said fixed platform, then determines the translation of this mobile platform , maintained in this position of maximum lifting, in the direction of advancement facing the exit of the furnace, a condition in which the sections placed on the movable platform 24 are made to advance by one step, then determines the lowering of this movable platform to the same height of its initial position, in its operative position shown in FIG. 5, with consequent arrangement of the sections on the consecutive zone, and finally causes the return of this mobile platform to its rest position with a translation movement which is the reverse of the previous one.

To determine these movements of the moving floor, suitable drive mechanisms acting on the moving floor itself are used.

Preferably, these actuation mechanisms consist of a series of worm screw jacks, acting on the eccentrics 28 of the mobile platforms 24 so as to determine first the lifting and then the lowering of the platforms themselves with consequent detachment of the sections from these platforms. , and their arrangement on the next zone, as well as consisting of a series of worm geared motors acting on the movable platforms 24 to determine their translation in the forward direction and by further gearmotors acting on said movable platforms to determine their translation in the opposite direction , up to the initial resting position.

Finally, the present drive mechanisms consist of a series of rack-and-pinion toothed gears connecting the longitudinal bars of the mobile platforms together, so as to transmit the driving force for movement without jerking and jolts, thereby avoiding possible damage. of the material being treated, and the movement by steps of the whole assembly is automatically terminated after a predetermined number of advancement steps, such as to keep the material under heat treatment inside the furnace for the predetermined time. Obviously, instead of in the manner described, it is possible to carry out the advancement by steps of the sections along the mobile platforms also in a different manner and with different drive mechanisms, provided that an automatic advancement of the sections through the furnace is always determined in the predetermined times, such as to subjecting each profile map to the necessary treatment, without thereby departing from the scope of protection of the present invention.

The operation of the furnace thus realized is already evident from the description made up to now of the structural characteristics of the furnace itself.

In fact, in this furnace each profile map transported by the conveyor means reaches the terminal end of the same, from where it is conveyed through a series of motorized rollers positioned there to the external lift, which is first lifted to the fixed platform located at the lowest level. high, placing this map in this position, and then this lift is subsequently raised to the respectively lower levels, placing each map on it from time to time. Subsequently, the map loading operations are repeated with the same sequence, so that each floor is always filled with the same number of maps, which are thus progressively transferred in the direction of advancement, and as soon as a series of maps reaches the at the exit of the kiln, it is selectively taken from the external lift and transferred from the same to the conveyor means that transport it to the storage area, while a new series of maps is further introduced into the kiln by means of the external lift, acting in synchronism with the previous lift, a condition in which the oven is always filled with maps, and can therefore always be kept at the same operating temperature.

Consequently, this furnace allows the carrying out of more homogeneous and uniform heat treatments of all the maps, eliminating the loading and unloading baskets of the maps and the operations required for them, and minimizing heat dispersion towards the outside during rapid operations. automatic loading and unloading of maps, a circumstance which avoids the need to repeat the preheating of the oven after each treatment cycle.

Claims (7)

CLAIMS 1. Furnace for heat treatment of metal profiles of various kinds, previously extruded and cut and stretched to the required sizes and preferably grouped in maps, the furnace comprising a large closed metal box-like structure, delimiting an internal chamber with a large capacity to contain metal sections, in which hot air is circulated with predetermined operating temperatures produced by generators known per se, said box-like structure being provided with an inlet for the sections to be treated and an outlet for the treated sections, which can be closed with respective doors, in wherein said inlet and outlet are preferably associated with conveyor means for transferring the sections, characterized by means for loading and unloading the sections with respect to said internal chamber (8), and means for transferring (13) the sections through the internal chamber (8 ), from the entrance to the exit of the same, for a time and with u at speeds such as to determine the necessary heat treatment of all the sections, said loading and unloading means being preferably made as a respective external lift and adapted respectively to introduce the sections to be treated into the internal chamber through said inlet, at different levels of height, and to unload the treated sections in the internal chamber, through said outlet, from the height levels respectively reached, said loading and unloading means and said transfer means (13) being automatically controlled by control means in such a way as to determining during each heat treatment cycle of the sections the introduction into the internal chamber (8) of as many sections to be treated as how many treated sections are unloaded. 2. Furnace according to claim 1, characterized in that each of said external elevators is provided with motorized rollers and is commanded to move vertically simultaneously with the other elevator, with opposite vertical directions of movement, said external elevators also being associated with sensor means for detecting the presence or absence of sections, suitable for enabling or disabling the operation of each lift in the presence or absence of the sections, respectively. 3. Furnace according to claim 2, characterized in that said transfer means (13) consist of a plurality of horizontal rectilinear shelves (21), of the fixed type, identical and superimposed on each other at different height levels, for the whole the extension of the furnace, and anchored to the base (10) of the same, and divided transversely to the furnace in a series of single separate sliding paths, said transfer means (13) being also constituted by a plurality of horizontal platforms ( 24), of the mobile type, cooperating with the corresponding fixed platforms (21) of each sliding path, and provided for the entire longitudinal extension of the same paths, said mobile platforms (24) being lowerable and liftable with respect to said fixed platforms ( 21) and being operated by control means with a series of movements designed to cause in succession the lifting and longitudinal translation of the sections, towards the direct zone consecutive with respect to the exit of the furnace, and then the lowering and deposition of the profiles on this area and the return of the movable platform moved to the initial position with a reverse translation movement to the previous one. 4. Furnace according to claim 3, characterized in that said fixed platforms (21) are structured at the top with a series of fixed bars or idle rotating rollers for their entire extension, with the exception of the ends of said sliding paths, which are structured with motorized rollers (15). 5. Furnace according to claim 4, characterized in that said movable platforms (24) are structured at the top with movable bars (25), arranged longitudinally to the furnace, parallel to said fixed bars or idle rotating rollers of the fixed platforms (21). 6. Oven according to claims 3 and 4, characterized in that said fixed platforms (21) and said movable platforms (24) are covered on their upper surface by at least one layer of material resistant to high temperatures, preferably of the Kevlar type. 7. Furnace according to claim 6, characterized in that said control means comprise a series of elongated shafts (26) with limited rotation, housed transversely to the internal chamber (8) of the furnace, parallel to each other, rotated by a group drive (27), each shaft (26) supporting a first and a second series of lever eccentrics (28, 29), of which each eccentric (28) of the first series is axially spaced from each eccentric (29) of the second series , and is fixed with one end to the rotating shaft (26) and with the other end it supports a pressure roller (30), constantly pressed against the lower surface of the corresponding mobile platform (24), or fixed to the same in articulated way, and of which each eccentric (29) of the second series is fixed with one of its ends with the rotating shaft (26) and is articulated with its other end with the lower surface of the corresponding fixed platform (21), said eccentric ci (28, 29) being angularly offset from each other to determine, during the rotation of said shafts, the lifting, translation and lowering movements of said mobile platforms (24), with the aid of drive mechanisms of the known type in self.