FR2982789A1 - Thermal insulation device for heat resistance mold intended for molding hot parts of installation, has studs formed of insulating material of high resistance to compression and for spacing two parts apart so as to place space between parts - Google Patents

Abstract

The device has studs (5) formed of insulating material of high resistance to compression, and for spacing a part (2) apart from another part (3) so as to place a space between the two parts. The studs are placed between the parts at an equidistant manner from/to each other. The space is adapted to accommodate an element (6) with a thermal conductivity lower than thermal conductivity of the studs. The insulating material is made of a laminated material containing silica glass fibers or aluminum foam. A low thermal conductivity material layer (9) i.e. aerogel layer is applied between the studs. An independent claim is also included for an installation.

Description

982 789 1 thermal insulation device for mold, mold equipped with such a device and installation comprising at least one such mold. The invention relates to a thermal insulation device for a mold which is intended for molding hot parts. In other words, the device according to the invention is designed to be implemented on a mold which is mounted in temperature to produce parts. Such molds are known under the name of mold "HR" ("Heat Resistance"). An example of such molds is described in WO 2005/025835. These molds are designed to rise between substantially 80 and 200 ° C, so as to confer, to the container made, physical and aesthetic characteristics meeting certain standards. Such molds are usually mounted on mold carriers. The disadvantage of the temperature rise of the molds is that the mold carriers also rise in temperature. The rise in temperature can be well supported by some alloys. However, for reasons of cost and weight, it is desired to make said mold gates in inexpensive and light materials, which implies that the latter must not exceed a critical temperature to retain some of their mechanical characteristics. At the origin of the invention, it was therefore sought to develop technical means for thermally isolating the HR mold from the mold holder that supports it. There are known systems for cooling a mold. For example, the documents FR 2 031 731 and FR 2 828 829 provide to equip the molds with internal conduits in which is circulated cooling water. Such a technique can not be implemented in the mold holders, because cooled mold holders could lower the mold temperature. However, it is imperative to keep the mold hot. The invention therefore has the primary objective of providing means that both: - maintain the mold carrier at a temperature below a certain limit, this limit being the one from which the mechanical characteristics of the mold carrier degrade, and - do not increase the energy consumption of the installation to maintain the mold temperature and, at best, reduce the energy consumption. WO 2005/025835, cited above, provides to place behind the mold an insulating wall to prevent, as far as possible, heat losses generated by a mold resistance in the surrounding environment. The invention aims to provide an alternative solution to the use of a wall of insulating material. The invention also aims to achieve thermal insulation performance at an affordable cost.

The alternative solution according to the invention offers results superior to those obtained by said wall, in terms of insulation of the mold carrier on which the mold is fixed. Furthermore, the solution according to the invention also provides mechanical strength performance, in terms of compressive strength, which are at least as good as those of the thermally insulating wall which is provided in WO 2005/055835. Finally, the solution according to the invention makes it possible to meet certain congestion criteria that it is imperative to respect. In particular, the minimum thickness necessary for the implementation of the solution according to the invention is a few millimeters, and for example 5 mm as in the application example which will be described later. To this end, the invention relates to a thermal insulation device for a mold, said mold comprising a first part that can be heated and a second part to which said first part is fixed. The device is remarkable in that it comprises studs made of an insulating material with high compressive strength, to space said first piece of said second piece, so as to provide between said first and second pieces a space able to accommodate a element having a thermal conductivity lower than the thermal conductivity of said pads.

Thus produced, the device according to the invention makes it possible to use materials that perform better than the material of which the thermally insulating wall is made in document WO 2005/025835, and at a lower cost, since these materials are used in a smaller quantity to achieve plots, not an entire wall. Thus, the device is less expensive and more mechanically efficient. In addition, the device according to the invention makes it possible to achieve higher thermal insulation performances thanks to the presence of the pads. Indeed, such an embodiment allows the use of more efficient thermally insulating elements, which have very low mechanical strength characteristics, and which are inexpensive, such as air for example. We then obtain a cheaper device, and we can also control the size depending on the height of the pads. The device according to the invention may also have the following characteristics, taken separately or in combination: the insulating material with high compressive strength, in which the pads are made, may be any of the following materials: laminate based on glass fibers, silica or aluminum foam; - The pads may be disposed between said first and second parts equidistantly from each other; - The studs may be arranged in rows between said first and second parts; the device may comprise a layer of low thermal conductivity material applied between the pads on said first piece; the layer of material with a low thermal conductivity may be an airgel layer; the layer of material with low thermal conductivity may have a thickness less than that of the pads; the first piece may be a mold and the second piece may be a mold-holder; the first part may be an insert and the second part may be a mold; the element filling the space between the first and second parts may comprise air; and the element filling the gap between said first and second parts may comprise silica airgel.

The invention also relates to a mold equipped with a device according to the invention, and an installation comprising at least one such mold. According to some advantageous embodiments, the mold of the installation installation is equipped with a device where the element filling the space between said first and second parts is air, and it is also equipped with a system ventilation device connected to said space between said first and second parts. According to another variant of the installation according to the invention, the mold is positioned on a carousel, the space provided between the two said parts in said mold communicates with an air inlet opening in said mold, and with an air outlet opening in said mold, and the inlet opening is connected to an air scoop, said scoop being oriented in a direction tangent to the rotation of the carousel, and being open on the direction of rotation so as to generate a displacement of air in said space by the rotation effect of said carousel. To be able to be executed, the invention is described in a sufficiently clear and complete manner in the following description which is, in addition, accompanied by drawings in which: FIG. 1 very schematically illustrates a mold comprising two half-molds, each half mold being equipped with a device according to the invention and being fixed on a mold carrier, the mold being shown in longitudinal sectional view, - Figure 2 shows a half-mold of Figure 1, in rear view, FIG. 3 very schematically illustrates two molds according to the invention, mounted on a carousel, in sectional view, FIG. 4 illustrates a first variant embodiment of the device according to the invention, equipping a half-mold illustrated with a view to longitudinal section, Figure 5 illustrates a second embodiment of the device according to the invention, equipping a half-mold shown in longitudinal sectional view. In the following description, the terms lower, upper, upper, lower, etc. are used with reference to the drawings for greater ease of understanding. They should not be understood as limitations of the scope of the invention. Figure 1 shows a first embodiment of a device according to the invention. The device is implemented on a mold 1, comprising in particular two parts: A first part 2 is able to be heated: it is in this case two half-molds 20 and 21, able to accommodate a preform to form a bottle by stretch blow molding. A second piece 3 is designed to support the first piece 2 able to be heated: it is in this case mold holders 30 and 31 on which are fixed respectively the two half-molds 20 and 21. The half-molds 20 and 21 are conventional half-molds, such as those described in the aforementioned patent application WO 2005/025835, which comprise, for example, circuits 4 for circulating a heating fluid, allowing the rise in temperature of the two half-molds 20 and 21. It should be understood that the two half-molds could be made differently without departing from the scope of the invention, as long as they include a piece suitable for being heated, no matter by which means. As for the mold holders 30 and 31, these are standard mold holders such as those usually used by those skilled in the art. It could be for example half-shells ("shell halves") mentioned in WO 2005/025835. In practice, each half-mold is thus no longer produced in one but in two distinct parts so that, according to the designations used in the document EP 0821641, each half-mold comprises on the one hand a carrier shell which is intended to be supported by the mold and secondly, a shell provided with a half-cavity of the container to be obtained which is adapted to be removably secured to the shell-holder by means of fixation. For example again, in an alternative embodiment according to the invention, the first part 2 could be an insert and the second part 3 10 could be a mold. As can be seen in Figure 1, the device comprises studs 5 which are arranged between an outer surface 22 of the half-molds 20 and 21, and an inner surface 32 of the mold carriers 30 and 31, the outer surfaces 22 and The pads 5 thus have the function of spacing the first piece 2 of the mold that is suitable for being heated (that is, the inner molds 30 and 31 are mounted on the mold holders 30 and 31. that is to say the two half-molds 20 and 21) of the second mold part 3 (the mold carriers 30 and 31), on which the first part 2 is fixed. A space can thus be provided between the first and second parts 2 and 3 of the mold, and between the pads 5 themselves which constitute point spacers of the two parts 2 and 3. The pads 5 are made of an insulating material with high compressive strength. This is for example a laminated material based on silica glass fibers, or even aluminum foam. The laminated material based on silica glass fibers is preferably chosen because it is the material whose quality / price ratio is the most advantageous. The free space between the first and second parts 2 and 3 is filled with an element 6 which has a thermal conductivity which is lower than the thermal conductivity of the pads 5. This element 6 is air.

By way of example, the thermal conductivity of the aluminum foam is substantially 0.188 W / m / K, whereas the thermal conductivity of the air is substantially 0.028 W / m / K. In order not to increase considerably the bulk of the mold, it is expected that the pads 5 have a thickness (e) not exceeding twice the thickness (el)) of the insulation space between the first part 2 and the second piece 3. Preferably, the pads 5 have a height of between 1 mm and 5 mm, this height being sufficient so that the heat communicated to them by the wall of the half-molds is not transmitted to the mold holders 30 and 31. To further improve the thermal insulation between the first and second parts 2 and 3, it is intended to circulate the air between the two parts 2 and 3. To do this, in the embodiment shown schematically on the 1, it is intended to connect the spaces between the first and second parts 2 and 3 to devices 7 equipped with fans 8. To allow good air circulation between the two parts 2 and 3, and between the pads 5, we plan to have the studs s as shown in FIG. 2. It will be noted that the studs 5 are arranged equidistantly and that they form two parallel rows between the two parts 2 and 3. To further increase the thermal insulation between the two parts 2 and 3 , it is expected to cover the outer surface 22 of the half-molds (and thus the first part 2) by a layer 9 of low thermal conductivity material. By "low thermal conductivity" will be understood a thermal conductivity which does not exceed 5 W / m / K. The layer 9 of material may be, for example, an airgel layer, whose thermal conductivity is of the order of 0.023 W / m / K and whose thickness is between 1 and 3 mm. In the context of another embodiment illustrated in FIG. 4, it will be noted that the device does not comprise a layer 9 of material on the outer surface 22 of the first part 2. It will therefore be understood that the presence of this layer 9 is not essential to the realization of the invention. It is however beneficial in terms of energy saving.

Similarly, Figure 5, which illustrates yet another alternative embodiment shows a device where there is no layer 9 of material on the outer surface 22 of the first part 1, and where the air 6 has been replaced by airgel silica.

In other words, the element filling the space left between the first and second parts 2 and 3, thanks to the presence of the pads 5, is only airgel silica 10. We will now focus on the embodiment which is illustrated in particular in Figure 3.

FIG. 3 shows an installation according to the invention, showing two molds 1, also in accordance with the invention, and comprising the same characteristics as those illustrated in FIG. 1. The installation actually comprises more than two molds 1, but only two molds have been shown for a better reading of FIG.

The molds 1 are arranged on a carousel 11, able to be rotated about its axis Z. In the context of this embodiment, the installation is equipped with a ventilation system ensuring convective air circulation. forced between the mold and the mold holder that supports it.

The ventilation system is different from the ventilation device 7 shown in FIG. 1. The ventilation system is connected to the space provided between the mold 20, 21 and the mold carrier 30, 31, otherwise the space provided between the first piece 2 and the second piece 3, spaced apart from each other by the studs 5.

Similarly to the example illustrated in Figure 1, the space between the two parts 2 and 3 communicates with at least one opening 40 of air inlet. This opening 40 is made in the lower part of the half-molds 20 and 21. Also similarly to the example illustrated in FIG. 1, the space 30 formed between the two parts 2 and 3 communicates with at least one outlet opening 41. of air, arranged for example in the upper position in the half-molds 20 and 21. In another embodiment, the air outlet could be constituted by venting circuits formed in the half-molds 20 and 21.

In the example illustrated in FIG. 1, the air inlet opening 40 is connected to the ventilation device 7, comprising a fan 8. In the example illustrated in FIG. 3, the air intake openings 40 molds are each connected to a scoop 42 of air.

The scoops 42 of air are made for example by bent tubular elements, whose output axis is oriented in a direction D tangent to the rotation of the carousel 11. The opening of the scoop 42, that is to say that is, the open end of the tubular element (not connected to the air intake opening 40 in the mold) is turned towards the direction of rotation of the carousel 11, so as to generate a displacement of air in the space left between the half-molds 20 and 21 and the mold carriers 30 and 31, respectively, solely by the rotation effect of the carousel. Thus, in this embodiment, there is no need for a fan device 7, which is a saving of energy and space in the operation of the installation. It is understood from the foregoing description how the invention makes it possible to isolate the half-molds of the mold holders that support them. It is thus possible to increase the temperature of the half-molds without, however, that this rise in temperature results in that of the mold-holders, which may be the cause of a problem of operation. The invention is however not limited to the embodiments that are presented above, and extends to the implementation of any equivalent means.

Claims (15)

REVENDICATIONS1. Thermal insulation device for mold (1), said mold (1) comprising a first piece (2) capable of being heated and a second piece (3) on which said first piece (2) is fixed, characterized in that it comprises studs (5) made of an insulating material with a high compressive strength, for spacing said first piece (2) from said second piece (3), so as to fit between said first and second pieces (2; 3) a space capable of accommodating an element (6; 10) having a thermal conductivity lower than the thermal conductivity of said pads (5). 2. Device according to claim 1, characterized in that said insulating material with high compressive strength, in which the studs (5) are made, is any of the following materials: laminated material based on glass fibers , silica or aluminum foam. 3. Device according to any one of the preceding claims, characterized in that said pads (5) are arranged between said first and second parts (2; 3) equidistantly from each other. 4. Device according to any one of the preceding claims, characterized in that said pads (5) are arranged in rows between said first and second parts (2; 3). 5. Device according to any one of the preceding claims, characterized in that it comprises a layer (9) of low thermal conductivity material applied between the pads on said first piece (2). 6. Device according to claim 5, characterized in that said layer (9) of low thermal conductivity material is an airgel layer. 7. Device according to claim 5 or 6, characterized in that said layer (9) of low thermal conductivity material has a thickness less than that of the pads. 8. Device according to any one of the preceding claims, characterized in that said first piece (2) is a mold and in that said second piece (3) is a mold holder. 9. Device according to any one of claims 1 to 7, characterized in that said first part (2) is an insert and in that said second part (3) is a mold. 10. Device according to any one of the preceding claims, characterized in that said element (6; 10) filling the space between said first and second parts (2; 3) comprises air (6). 11. Device according to any one of claims 1 to 9, characterized in that said element (6; 10) filling the space between said first and second parts (2; 3) comprises airgel (10) of silica . 12. Mold (1) equipped with a device according to any one of claims 1 to 11. 13. Installation comprising at least one mold (1) according to claim 12. 14. Installation according to claim 13, said mold (1) being equipped with a device according to claim 11, characterized in that it is equipped with a ventilation system (7; 8; 42) connected to said space between said first and second pieces (2; 3). 15. Installation according to claim 13, characterized in that: said mold (1) is positioned on a carousel (11), the space formed between said two pieces (2; 3) in said mold (1 ) communicates with an air inlet opening (40) in said mold (1), and with an air outlet opening (41) in said mold (1), and - said inlet opening (40) is connected to a scoop (42) of air, said scoop (42) being oriented on a direction (D) tangent to the rotation of the carousel (11), and being open on the side of the direction of rotation, so as to generate a displacement of air (6) in said space by the rotation effect of said carousel (11).