WO2012031872A2

WO2012031872A2 - Thermally insulating molded article, and method for the production thereof

Info

Publication number: WO2012031872A2
Application number: PCT/EP2011/064278
Authority: WO
Inventors: Frank Bailly; Dasaradh Kumar Patchala; Jörg STELZER
Original assignee: BSH Bosch und Siemens Hausgeräte GmbH
Priority date: 2010-09-07
Filing date: 2011-08-19
Publication date: 2012-03-15
Also published as: DE102010040346A1; CN103261822A; WO2012031872A3; EP2614322A2

Abstract

A method for producing a thermally insulating molded article comprises the following steps: a) providing a hollow mold (1); b) filling a free-flowing porous material (10) into the hollow mold (1); c) solidifying the free-flowing porous material (10) in the hollow mold (1); d) evacuating and sealing the hollow mold (1). The invention further relates to a thermally insulating molded article comprising a hollow mold (1) and a core made of porous material (10) solidified in the hollow mold.

Description

Heat-insulating molded body and

Process for its production

The present invention relates to a heat-insulating molded body, in particular for use in the construction of household refrigerators, and a method for the same

Production.

Most refrigeration appliance housings are currently manufactured by assembling preformed inner and outer skin members into a hollow walled housing and injecting into the cavities of the walls a plastic material which foams and solidifies therein. By foaming a complete filling of the cavities and a reliably reproducible quality of the insulation is achieved, regardless of possible manufacturing tolerances of the housing.

Vacuum insulation panels have long been known as elements for the production of refrigeration equipment housings. They are generally made up of a high grade

diffusion-tight plastic film and a porous filler, for example of zeolite, which is airtight coated by the film to a negative pressure in the pores of the

To maintain filling body. These vacuum insulation panels are generally plate-shaped, so that each panel at most a single wall of a

Refrigeration device housing can form and several panels must be joined together to form a complete housing. Such a process is considerably more laborious than the foaming described above. A refrigerator manufactured in this way would therefore be considerably more expensive than a conventional foam-filled, and would have no chance in the market despite the superior thermal properties of the vacuum insulation panels.

A hollow-walled housing assembled in a conventional manner from inner and outer skin elements or otherwise prefabricated

It is also impractical to fill in vacuum insulation panels, as any erosion may be required to accommodate the dimensions of the housing

Machining a vacuum insulation panel would destroy the vacuum and thus largely negate the insulation effect of the panel. Although it is possible to tailor the available as plate-shaped semi-finished support body to measure to insert them into a prefabricated mold cavity of a housing, then to evacuate the mold and close it. However, such an approach is at best practicable if the moldings with high accuracy

fit together and fill the existing space in the mold cavity exactly, otherwise give the walls of the mold during evacuation and in places where they are not sufficiently supported by the moldings, can tear. A high dimensional accuracy of the mold is not feasible with the usual methods of deep drawing. Although it is also possible to fill cavities between the shell and the support body before evacuation, but also this is time consuming and therefore expensive.

The object of the invention is therefore to provide a simple, inexpensive and flexible method for manufacturing a thermally insulating molding or a

specify heat-insulating molded body, which allows to assemble a refrigerator unit housing with excellent thermal properties in a simple and inexpensive way.

The task is solved on the one hand by a manufacturing method with the steps:

a) providing a mold;

b) filling a pourable porous material in the mold;

c) solidifying the pourable porous material in the mold;

d) evacuate and close the mold.

By filling the porous material in a pourable state into the mold, it can ideally adapt to its dimensions, even if these fluctuate, possibly due to the method used to provide the mold.

Before filling the pourable porous material, a protective layer can be inserted into the hollow mold in order to prevent the hollow mold itself from being damaged and, in particular, from leaking due to a pressure acting on the solidification of the material in the hollow mold.

As a protective layer is in particular a gas-permeable mat of a fibrous material into consideration, on the one hand is able to the porous material of the Keep hollow mold away, on the other hand, but at least not impaired evacuation of the mold, preferably even supported.

The solidification may in particular comprise pressing the pourable porous material. Alternatively or cumulatively to the above, the solidification may also include activating a binder.

In the latter case, it may be expedient if the pourable porous material and the binder are filled in a suspended or dissolved in a liquid form and to activate the binder, the liquid is eliminated. It may be sufficient to activate the binder, if this precipitates on evaporation of the liquid to the grains of the pourable porous material.

In order to fill the mold with the pourable porous material exactly, it may be useful to perform steps b) and c) several times.

Since the accuracy with which the solidified housing material of the finished molded body fills the mold does not depend on their dimensions or deviations of these dimensions from a default value, the mold can be provided in a simple and economical manner by deep drawing.

The object is further achieved by a heat-insulating molded body having a hollow shape and a core of porous material solidified in the hollow mold.

To form several walls of a refrigerator body, the core of the

heat-insulating molding preferably at least two substantially rectangular plates arranged to each other. Particularly preferably, the

heat-insulating moldings a complete heat-insulating body of a

Form refrigeration device. The hollow mold preferably has a flange surrounding a filling environment. This is on the one hand useful to provide the hollow body by deep drawing, on the other hand, it can also be used after evacuation to seal a sealing film and thus to close the hollow body airtight. The mold should be undercut to allow for secure filling without the formation of insufficiently filled areas which, when evacuated, would collapse under the externally applied air pressure.

The sealing film may in particular form an outer side of a rear wall of the body of the finished refrigeration device.

Further features and advantages of the invention will become apparent from the following description of embodiments with reference to the accompanying figures. Show it:

Figure 1 is a perspective view of a mold for use in the manufacture of the molding according to the invention.

FIG. 2 shows a section through the hollow mold of FIG. 1 during a first step of the production method according to the invention; FIG.

Fig. 3 is a section analogous to FIG. 2, a second step of

Manufacturing process shows; and

Fig. 4 is an analogous to FIG. 2 section showing a third step of

Manufacturing process shows;

5 shows a detail section through the hollow mold according to a development of the

inventive method in a first manufacturing step; and

FIG. 6 shows a section analogous to FIG. 5 in a subsequent production step. FIG.

Fig. 1 shows a mold for the manufacture of a refrigerator body according to the present invention. The mold 1 is deep-drawn from a plastic plate, similar to the inner containers of conventional refrigerators. This includes the mold 1, an inner rear wall plate 2, a (in the perspective of FIG. 1 down

facing) front frame 3 and between the front frame 3 and the inner back panel 2 extending inner side wall, floor and ceiling panels 4, 5 and 6, respectively. In addition to this, outer side wall, floor and ceiling panels 7, 8 and 9 adjoin the outside of the front frame 3. A in the perspective of Fig. 1 upwardly facing cavity of the mold 1 must with

Insulation material are filled to form a heat-insulating housing. This is done as shown in Figures 2 to 4. A pourable, granular or powdery highly porous filling material 10 is filled into the mold 1. It fills the narrow, due to the production of the mold 1 by deep drawing slightly upward widening gaps 12 between the inner and outer plates 4, 7, 5, 8 and 6, 9 substantially completely.

The filled material 10 is compressed with a retracting from above into the mold 1 piston 11, as shown in Fig. 3. The piston 11 may, as shown in FIG. 3, be flat to compress the filler 10 after complete filling of the mold 1 on the entire open rear side. In order to achieve a sufficient compression of the filling material 10 also in the vicinity of the front frame 3, it may be appropriate, the spaces between the inner and outer plates 4, 7; 5, 7 and 6, 9 to fill only gradually and after each filling step, first introduce a piston, not shown, which is shaped to engage in the interstices 12, and to use the piston 1 1 only when the gaps 12 completely filled in this way and are compacted and essentially only has to be filled over the inner rear wall panel 2.

After - in one or more filling and compression steps - the mold 1 is completely filled and the filled material 10 is compressed in the mold 1 to a solid core, the mold 1 is placed as shown in Figure 4 in a vacuum chamber 13, and this is evacuated, whereby the air escapes from the pores of the filling material 10. If a desired negative pressure is achieved in this way, a cover 14 is placed over the open back of the mold 1 and glued or welded to a surrounding the open back surrounding flange 15 airtight. The flange 15 corresponds to an edge region of the plastic plate used for the production of the mold 1, which was clamped during deep drawing. There are different types of filler for use in the molding according to the invention in question, such as granules of an open-cell plastic rigid foam, an airgel, zeolite, silica, etc. In particular at

Use of a hard, mineral filler and a thin-walled mold 1, the risk of damage to the mold 1 during compaction with the punch 1 1 can not be completely excluded. In order to avoid this danger, different approaches can be considered. One is, the filler does not dry into the mold

1, but suspended in a liquid which, moreover, may be enriched with a binder. Here, a solidification of the filling material 10 is achieved in the mold, by the extent that the liquid evaporates, the

Binder deposits on the filler particles and they glued together.

A disadvantage of this process is the long process time required to remove the liquid.

An alternative, preferred approach is shown in FIGS. 5 and 6: the hollow mold 1, which is only partially illustrated here, is designed with a porous nonwoven 16 or fabric prior to the introduction of the filling material 10. The web 16 or fabric is dense enough to prevent the subsequently filled filler material 10 from directly contacting the mold 1. A protruding edge region 17 of the fleece 16 also keeps the circumferential flange 15 of the hollow mold substantially free of particles of the filling material 10.

After the mold 1 has been filled with the filling material 10 and this has been compacted, the edge region 17 of the nonwoven fabric 16 as shown in Fig. 6, on the back wall plate

2 beaten back on the compacted molded body, so that the flange 15 is exposed and the cover 14 can be tightly attached thereto.

Claims

Anspruch [en] A method of manufacturing a heat-insulating shaped body comprising the steps of: a) providing a mold (1);

b) filling a pourable porous material (10) in the mold (1); c) solidifying the pourable porous material (10) in the mold (1); d) evacuating and closing the mold (1).

A method according to claim 1, characterized in that prior to filling the pourable porous material (10) a protective layer (16) in the mold (1) is inserted.

A method according to claim 2, characterized in that the protective layer (16) is a gas-permeable mat of a fibrous material.

Method according to one of the preceding claims, characterized in that the solidification comprises pressing the pourable porous material (10).

Method according to one of the preceding claims, characterized in that the solidification comprises activating a binder.

A method according to claim 5, characterized in that the pourable porous material (10) and the binder are filled in suspended or dissolved in a liquid form and for activating the binder the

Liquid is eliminated.

Method according to one of the preceding claims, characterized in that the steps b) and c) are performed several times.

8. The method according to any one of the preceding claims, characterized in that the hollow mold (1) is provided by deep drawing.

9. A heat-insulating molded body having a hollow mold (1) and a core of in the mold (1) solidified porous material (10).

10. A heat-insulating shaped body according to claim 9, characterized in that the core comprises at least two substantially mutually rectangularly arranged wall plates. 11. Heat-insulating molded body according to claim 9, characterized in that the shaped body (1) is a heat-insulating body of a refrigerating appliance, in particular a household refrigerating appliance.

12. Heat-insulating molded body according to one of claims 9 to 1 1, characterized in that the hollow mold (1) surrounding a filling opening

Flange (15), to which a sealing film (14) is sealed.

13. Heat-insulating molded body according to claim 12, characterized in that the hollow mold (1) is undercut.

14. A heat-insulating molded body according to claim 12 or 13, as far as dependent on claim 11, characterized in that the sealing film (14) a

Outside forms a back wall of the body.