WO2017077376A1

WO2017077376A1 - System for cooling an extruded product leaving an extruder

Info

Publication number: WO2017077376A1
Application number: PCT/IB2016/001561
Authority: WO
Inventors: Valerio Presezzi
Original assignee: Presezzi Extrusion S.P.A.
Priority date: 2015-11-03
Filing date: 2016-10-28
Publication date: 2017-05-11
Also published as: ITUB20155180A1

Abstract

A system for cooling an extruded product (100) at the outlet of an extruder (2) comprises a support surface (3) adapted to receive such product (100) from the extruder (2) and relative to which the product is moved, said surface being arranged within a fixed structure (10) having lateral uprights (11) and a top placed above such surface (3), within such structure dispensing means (15, 150) being present that are adapted to direct a cooling fluid towards the product (100) placed on the surface (3). Such fluid (16) simultaneously contains air and water drops, the latter thus being nebulized when it reaches such product.

Description

SYSTEM FOR COOLING AN EXTRUDED PRODUCT LEAVING AN EXTRUDER

The object of the present invention is a system for cooling an extruded product at the outlet of an extruder, according to the preamble of the main claim.

As is known, an extruded product must be cooled in a controlled manner at the outlet of the extruder in order to confer specific mechanical characteristics to the product itself, due to a thermal quenching treatment and in order to prevent deformations of such product, improving the cooling in accordance with the architectural shapes of such product and with the physical characteristics of the material that constitutes it .

Currently, cooling systems (also indicated as "cooling hoods") use a cooling fluid which can be either water or air. Examples of such systems are described in EP 2 484 785, US 3 513 503, JP 2002 144408, JP H06 23826. Other systems, like that described in US 6 216 485, DD 211 314 and DE 88 10 085 employ both air and water: normally water is employed as cooling fluid, while air is often employed for creating (air) barriers around the zone where the extruded product is situated, such product being hit by sprayed or even nebulized water for the cooling of the product.

The cooling fluid is dispensed by a plurality of nozzles placed above, on the side of and below the extruded product while the latter is placed, movably, on a support surface that receives it at the outlet of the extruder. Such system normally has a fixed structure comprising lateral uprights and a top placed above such product. At such top, means are present which dispense such "cooling" fluid towards the extruded product: such means can be a plurality of openings placed along the support surface, through which air exits, said air being fed by at least one fan. Other slits or openings placed on the side of and below the abovementioned support surface also emit air towards the movable surface.

Alternatively, (or in addition), such slits can be substituted (or assisted) by nozzles connected to water sources, in a manner such to allow the water to be sprayed by said slits towards the extruded product.

Such cooled fluid feeder means are inserted within the structure and preferably associated with a movable cover adapted to be lifted from and lowered towards the support surface so as to allow the cooling fluid to be sent towards the surface with maximum effectiveness. Such cover is made of a single block of length that can vary as a function of the requirements. Each fan is placed outside the movable cover (within or outside the structure or building that contains the press) and is connected with the slits by channels made of sheet metal, for example; each slit comprises a shaped mouth that accelerates the air flow, and each slit distributes the air flow on the surface of the product.

There is also the possibility to regulate the air flow into various zones of such cover in a different manner, as a function of requirements and the shape of the section.

In the case of water dispensing, the water is supplied by a plurality of nozzles placed within the movable cover and preferably arranged on different rows in order to cover the entire surface of the extruded product and a wide length of the latter. Normally, nozzles of different size are employed, all the nozzles or separately each nozzle being fed with water.

A suitable circuit supplies the water (under pressure, by means of pump) to the nozzles; the circuit is provided with proportional valves for varying the water flow directed to the nozzles. Finally, the dispensed water is collected, cooled and filtered and newly supplemented in order to make up for the part that evaporated and that which was inevitably lost since the cover is not sealed. The nozzles can be fixed or movable.

Such known solutions that provide for cooling the extruded product with air or with water have various drawbacks. The solution that uses water has the main drawback of generating a calefaction effect on the product so that the water, in contact with the hot surface of the product, immediately evaporates, forming a vapor layer on the product itself. The water that is subsequently sprayed on the extruded product "floats" on such vapor layer. Since vapor is a poor conductor with respect to water, less heat is removed from the product.

In addition, the known solutions have high energy consumption, they comprise large-size structures and provide for a considerable waste of air and water. In addition, in the known solutions, the movable cover has large size and is single-piece, which does not allow gradually intervening in the cooling of the product so as to limit the quenching thereof.

The use of only air for cooling the extruded product instead has low effectiveness if compared with the use of water .

The object of the present invention is to offer a cooling structure for an extruded product at the outlet of an extruder which overcomes the drawbacks of the prior art . In particular, the object of the invention is to offer a structure of the abovementioned type which allows obtaining an improved cooling of the product with respect to the known solutions, with a lower energy consumption with respect to the latter.

Another object is to offer a system of the abovementioned type which cools the product with the use of water in which, however, the water consumption is less than that of the analogous known structures, given the same product cooling conditions (initial temperature, final temperature, cooling times, etc.) .

Another object is to offer a structure of the abovementioned type which allows an optimal cooling of extruded products with asymmetric or strongly asymmetric profiles .

These and other objects which will be clear to the person skilled in the art are achieved by a cooling system according to the main claim.

For a greater comprehension of the present invention, the following drawings are enclosed merely for exemplifying and non-limiting purposes, in which:

figure 1 shows a top perspective view of a system according to the invention;

figure 2 shows a top perspective view of a part of the system of figure 1 with some parts omitted for greater clarity;

figure 3 shows a section view according to line 3-3 of figure 1, the figure showing a detail of the system of figure 1 ;

figure 4 shows a view analogous to that of figure 3, but with the system operating on an extrusion product different from that of figure 3 ;

figure 5 shows a transparent perspective view of a part of the system of figure 1 ;

figure 6 shows a perspective view of a portion of the part of figure 5;

figures 7A-7D show different forms of a fluid jet employed for cooling an extruded product with the system of figure 1 ;

figure 8 shows a section according to line 8-8 of figure 1 ;

figure 9 shows a side view of the system of figure 1 ; figure 10 shows a partial front perspective view of the system of figure 1 ;

figure 11 shows an enlarged side view of a variant of a detail of the system of figure 1 ;

figure 12 shows a partially exploded perspective view of a different embodiment of a part of the system of figure 1 ;

figure 13 shows a front perspective view of the part of figure 12; and

figure 14 shows a perspective view of a component of the part of figure 12.

With reference to the abovementioned figures, a system for cooling an extruded product 100 is generically indicated with 1. It is placed at the outlet of an extruder 2 and comprises a support surface 3 adapted to receive such product from the extruder 2. The support surface 3 can comprise a plurality of rollers or cylinders 6, idle or motorized, on which the product slides, e.g. driven by a known drive member 7, movable on a track 8 thereof (see figure 8) and placed on the side of the system 1.

The system 1 comprises a fixed structure 10 having uprights 11 associated with longitudinal crosspieces 12 (parallel to the axis W of the support surface and to the axis of the extruder) . Other transverse crosspieces 13 join the longitudinal crosspieces 12 and with the latter define a top of the system 1.

Such system comprises a first and a second plurality of spray nozzles 15 (placed above and on the side of the surface 3) and 150 placed below the surface 3 and acting as dispensing means for a fluid 16 towards the product 100 placed on the surface 3. Such fluid is a "fog" simultaneously containing water and air (i.e. it is nebulized water) which, when dispensed towards the product, reaches it in each part thereof, cooling it, whatever the section or shape of such product. The fluid hence contains both water, which offers high effectiveness in cooling the product 100, and air, which allows conveying the aforesaid fluid (in very fine droplike shape, with dimensions slightly larger than one micron) to the most hidden parts of the product 100 (which is useful, if such product comprises very complex sections ) .

In order to allow each nozzle to simultaneously emit water and air (thus creating a "fog"), each nozzle is connected, by means of pipes (not shown), simultaneously with at least one water tank 19, e.g. placed below the surface 3, and with air compressors 20 placed on the sides of the structure 10 (or in another suitable position) . Such compressors feed the air tanks 20A placed, in the example, above the structures 10 and directly connected, by means of said pipes, to the nozzles 15 and 150. Due to such connection, the water is pumped in a known manner from the tank 19 into said pipes and analogously the air is moved from the tanks 20 towards the nozzles. The water, together with the air moved by the compressors 20, reaches the nozzles 15 and 150 and exits therefrom completely nebulized due to the presence of air therein. As stated, the water drops have the size of a "fog" and in such form they are directed towards the product to be cooled.

When the fluid (air and water) hits the extruded product (at initial temperature or at the outlet of the extruder 2, it is about 500°C), the water present therein evaporates nearly instantaneously, cooling such product; at the outlet of the structure 10, the latter has a temperature much less than the initial temperature (and equal to about 100°C-150°C) .

In such a manner, by having a high water evaporation (since, being nebulized, it covers the entire surface of the product, reducing the calefaction effect to negligible values), it is possible - given the same final cooling with the known solutions - to considerably reduce the quantity of water used and consequently the power employed for the pumping. In addition, in the fluid that passes from the nozzles, there is a lower flow rate of air with respect to that present in the nozzles of the known solutions which only use air for cooling the extruded product, which also proportionally affects the consumptions of the system.

The nozzles 15 and the nozzles 150 are movable and can assume different tilts with respect to the product 10 as a function of the shape of the latter. In particular, the angular position of such nozzles is controlled and commanded by a control unit of the system, e.g. a microprocessor, which has the shape of the extruded product in its memory, e.g. by knowing the shape of the normal extrusion matrix of the extruder 2 stored in such memory .

In particular, the nozzles 15 (above and on the side of the surface 3) and 150 (below the surface 3), separately or partly or entirely grouped together, are associated with carrying members 22 and 220, respectively. Through such members, the air and water reaches the aforesaid nozzles, e.g. since said members contain the abovementioned air and water pipes.

Such carrying members 22 and 220 rotate around the longitudinal axis thereof (parallel to the abovementioned axis W) .

In particular, each carrying member 22 is hinged at opposite ends thereof to a movable body or cover 23 adapted to be superimposed on and to be lifted from the surface 3. The carrying members 22 associated with such cover 23 are arranged in pairs, in a positioned superimposed on the surface 3 and fixed with a longitudinal member 25 placed below such cover 23; other members 22 are instead placed at lateral sides of such cover 23. The longitudinal member 25, parallel to said member 22 placed above the surface 3, carries a body 30 with which actuators 31 (hydraulic, pneumatic, hydropneumat ic or electric) are associated, fixed to a projection 33 associated with the adjacent members 22 by means of a pusher (e.g. movable piston) 34. By driving such actuators 31, there is the rotation of the members 22 adjacent to the longitudinal member 25 and placed above the surface 3, with the consequent angular rotation of the nozzles 15.

In addition, the longitudinal member 25 is subjected to actuators 40 (hydraulic, pneumatic, hydropneumat ic or electric) adapted to move such longitudinal member axially (parallel to the axis W) by means of a transmission 41 hinged at 42 to said actuators 40. The latter are integral with the cover 23.

The carrying members 22 placed on the side of the surface 3 are instead moved by actuators 45 thereof fixed to the cover 23. Analogously, the carrying members 220 of the nozzles 150 placed below the surface 3 are moved by actuators 450 thereof fixed to a structure fixed to the aforesaid surface 3. Such actuators 450, through a pusher 340, drive the members 220 in rotation in order to move the angle of the nebulized flow emitted by the nozzles 150. The cover 23 is movable with respect to the surface 3 by means of actuators (hydraulic, pneumatic, hydropneumatic or electric) 50 fixed to the fixed structure 10 and placed on top of the latter. Preferably, moreover, the surface 3 cooperates with a plurality of covers 23 (three in the figures) that are autonomously movable with respect to each other so as to allow the actuation of nozzles 15 only fixed to the cover brought into a position approached to such surface, in order to optimize the cooling temperature profile of the extruded product 100 along such surface at the outlet of the extruder .

Each single cover 23 can cool the extruded product 100 to predefined temperatures selected as a function of the shape, mass and section of the product. The cooling temperatures depend on the temperature of the water which is dispensed in the single section. The temperature is controlled by a control unit (not shown) of the system 1 which controls the operation of each member (movable or not) of the latter.

This ensures a uniform cooling of the product 100, whatever its shape and section. For example, in the case of a product 100 with asymmetrical form, the aforesaid unit moves the nozzles 15 and 150 such that the nebulized fluid reaches each part of the product, in order to cool it in an optimal manner. For example, as shown in figures 3-7D, the fluid 16 can assume a conical shape with elliptical opening with greater axis orthogonal or tilted with respect to the axis W. All this is a function of the shape of the extruded product which the control unit can directly receive, by importing the shape of the extrusion matrix therein.

Finally, fans 490 and 491 placed at the end of the surface 3 create blades of air, between which said surface is situated.

According to the invention, there can be an optimal cooling of the extruded product, saving water and energy both from the water pump and for the air compressors.

In figure 11, a variant of the invention is shown according to which a nozzle 15 is moved to an articulated quadrilateral 120 subjected to a lever 121 moved by the actuator 45 and hinged at 123 to the carrying member 22 (to which the nozzle 15 is also hinged at 124) .

In figures 12-14, another variant of the invention is shown where the surface 3 is associated with covers 23, bearing carrying members 22 within which the ducts 201 and 202 are placed, and fixed carrying members 220 within which the ducts 201 and 202 are placed. The latter are integral with the nozzles 15 and 150 which simultaneously emit air and water in nebulized form towards the product 100. As in the preceding case, the nozzles 15 and 150 are movable through the movement of the members 22 and 220 obtained by means of actuator (e.g. electric) 240 acting on a shaft 241 so as to rotate it and vary the tilt of the nozzles with respect to the product.

Also, this variant, along with others that can be inferred from the preceding description, is to be deemed as falling within the scope of the invention, defined by the enclosed claims.

Claims

1. System for cooling an extruded product (100) at the outlet of an extruder (2) comprising a support surface (3) adapted to receive such product (100) from the extruder (2) and relative to which the product is moved, said surface being arranged within a fixed structure (10) having lateral uprights (11) and a top placed above such surface (3), within such structure dispensing means (15, 150) being present that are adapted to direct a cooling fluid towards the product (100) placed on the surface (3), characterized in that said dispensing means (15, 150) are nozzles connected, by means of pipes, simultaneously with at least one water tank (19) and with at least one air tank, said water and air simultaneously reaching the nozzle (15, 150) and exiting therefrom, creating the cooling fluid, such fluid (16) therefore being simultaneously defined by air and water that is nebulized, the cooling fluid being nebulized and being dispensed in fog form.

2. System according to claim 1, characterized in that the cooling fluid (16) is dispensed above, on the side of and below the surface (3) on which the product (100) is situated .

3. System according to claim 1, characterized in that the nozzles (15, 150) are placed above, on the side of and below said surface (3), such nozzles being angularly movable and lockable in different spatial positions with respect to the product (100) towards which they direct the nebulized fluid (16), so as to direct said fluid from optimal angles towards such product.

4. System according to claim 3, characterized in that the nozzles (15), placed above and on the side of the surface (3) on which the product lies, are associated with carrying members (22) angularly movable around a longitudinal axis thereof parallel to a longitudinal axis (W) of said surface (3), fixed actuators (31, 45) being provided that are adapted to generate such movement .

5. System according to claim 1, characterized in that it comprises at least one cover (23) of the surface (3) supporting the product (100), said cover being associated with carrying members (22) for the nozzles (15) placed above and on the side of such surface (3), said cover being movable with respect to such surface and to the fixed structure (10) placed around said surface (3) .

6. System according to claim 5, characterized in that the fixed structure (10) supports hydraulic, pneumatic, hydropneumatic or electric actuators for the movement of each movable cover (23) .

7. System according to claim 5, characterized in that it comprises a plurality of movable covers (23), each cover being movable independently from every other cover, the nozzles (15, 150) of each cover being actuatable independently of the nozzles of every other cover.

8. System according to claim 3, characterized in that the movement and the locking of the nozzles (15, 150) in spatially different positions is automatically obtained as a function of the shape of the extrusion product (100) to be subjected to cooling, said movement being controlled by a control unit of the system as a function of the shape of the extruded product, said shape being stored in a memory unit of said control unit.

9. System according to claim 3, characterized in that the nozzles (150) placed below the surface (3) carrying the product (100) are associated with carrying members (220) angularly movable around a longitudinal axis thereof parallel to the longitudinal axis (W) of such surface, such carrying members being hinged to the fixed structure (10) of the system and being subjected to the action of actuators (450) carried by such structure (10) .