Method for producing a molded insulating part, molded insulating part produced by said method

Abstract

A process for producing a molded insulating part, a molded insulating part and a casting tool for the production of an inorganic pulp composed of water, glass fibers and/or mineral fibers and sheet silicate, introduction of the pulp into a cavity of a casting tool whose wall is at least partially water-permeable, which cavity has on at least one side the negative shape of the molded insulating part to be produced, removal of the aqueous fraction present in the pulp, opening of the casting tool and subsequent taking-out of the molded insulating part produced. The pulp produced using water for producing the molded insulating part comprised a glass fiber/sheet silicate mixture or mineral fiber/sheet silicate mixture has a proportion of exclusively synthetic sheet silicate (5) in the range from 0.5% to 2.5% and a proportion of glass fibers and/or mineral fibers (4) of from 0.3 to 1.5%.

Claims

1. A process for producing a molded insulating part (1) for thermal insulation, consisting of the following process steps: producing an inorganic pulp (2) composed of water (3), glass fibers and/or mineral fibers (4) and sheet silicate (5); wherein the glass fibers and/or mineral fibers (4) are heat resistant up to a temperature ranging from 600 C. to above 1000 C., introducing the pulp (2) into a cavity (6) of a casting tool (7) whose wall is at least partially water-permeable, which cavity (6) has on at least one side the negative shape of the molded insulating part (1) to be produced, removing the aqueous fraction present in the pulp (2), by using a sub atmospheric pressure, produced within the casting tool (7) relative to normal atmospheric pressure, opening of the casting tool (7) and subsequent taking-out of the molded insulating part (1) produced.

2. The process as claimed in claim 1, wherein the withdrawing of water is accelerated by a temperature increase to a value above room temperature produced in the casting tool (7).

3. The process as claimed in claim 1, further comprising the step of introducing the pulp (2) into the cavity (6) of the casting tool (7) a plurality of times in succession and withdrawing the water (3) therefrom in each case.

4. The process as claimed in claim 3, wherein the pulp comprises a first material and a second material, the two materials differing in nature or composition; and the two materials are introduced in succession into the cavity (6) of the casting tool (7).

5. The process as claimed in claim 3, wherein pulp (2) is introduced a plurality of times into the cavity (6) of the casting tool (7) only in locally delineated regions of the molded insulating part (1) to be produced.

6. The process as claimed in claim 1, wherein the casting tool (7) comprises of a lower tool (8) and an upper tool (9) which closes this has a suction device (10.2) which is connected to or integrated into the upper tool (9) and by which the molded insulating part (1) is, after it has been manufactured, drawn in and detached from the lower tool (8) so that it can be taken from the opened casting tool (7).

7. The process as claimed in claim 1, wherein the lower tool (8) has, for detachment of the molded insulating part (1), a pressure device (11.2) or is connected to a pressure device (11.2) by means of which the molded insulating part (1) is, after it has been manufactured, released from the lower tool (8).

8. The process as claimed in claim 1, wherein the molded insulating part (1) taken from the casting tool (7) is transferred to a drying unit in which the residual moisture is withdrawn from the molded insulating part (1) by means of heat treatment at from 200 C. to 250 C.

9. The process as claimed in claim 1, wherein the molded insulating part (1) taken from the casting tool (7) is transferred to a firing apparatus in which water of crystallization is withdrawn from the molded insulating part (1) by means of a subsequent firing procedure.

10. The process as claimed claim 1, wherein the casting tool (7) is cleaned after the molded insulating part (1) has been taken out.

11. The process as claimed in claim 10, wherein the cleaning is carried out by a waterjet, pressurized air cleaning or by means of the aqueous fraction withdrawn from the pulp.

12. The process as claimed in claim 1, wherein the molded insulating part (1) is, in the casting tool (7), poured directly into an outer wall (13) which accommodates this after its manufacture and is provided with numerous through-holes (12), the through-holes (12) are utilized for removing the water (3) from the pulp (2).

13. A molded insulating part produced by a process claimed in claim 1, wherein the pulp (2) produced using water (3) for producing the molded insulating part (1) comprises of a glass fiber/sheet silicate mixture or mineral fiber/sheet silicate mixture has a proportion of synthetic sheet silicate (5) in the range from 0.5% to 2.5% weight of the pulp and a proportion of glass fibers and/or mineral fibers (4) of from 0.3 to 1.5% weight of the pulp.

14. The molded insulating part as claimed in claim 13, wherein the sheet silicate (5) is a powder having the constituents silicon dioxide (SiO.sub.2) and aluminum oxide (Al.sub.2O.sub.3).

15. The molded insulating part as claimed in claim 13, wherein the sheet silicate (5) has a proportion of silicon dioxide (SiO.sub.2) in the range from 55% to 65% weight of the pulp, a proportion of magnesium oxide (MgO) in the range from 25% to 30% weight of the pulp, a proportion of lithium oxide (Li.sub.2O) in the range from 0.7% to 0.9% weight of the pulp and a proportion of sodium oxide (Na.sub.2O) in the range from 2.5% to 3% weight of the pulp.

16. The molded insulating part as claimed in claim 13, wherein the glass fibers and/or mineral fibers (4) for producing the pulp (2) are amorphous fibers or crystalline fibers.

Description

DETAILED DESCRIPTION OF THE INVENTION

(1) The figures show:

(2) FIG. 1: a simplified in-principles flow diagram of the production of a pulp,

(3) FIG. 2: a schematic greatly simplified depiction of a casting tool and

(4) FIG. 3: a view into an outer wall of an exhaust gas catalyst of a motor vehicle with molded insulating part inserted therein.

(5) The production of a pulp 2 depicted in simplified form in FIG. 1 is effected by mixing the basic constituents in a vessel 16. Here, water 3, glass fibers and/or mineral fibers 4 in the form of high-temperature wool and sheet silicate 5 are introduced into the vessel 16 and mixed by means of a stirring device 15 until a homogenous pulp 2 has been formed. Firstly, the synthetic sheet silicate 5 is introduced slowly to cold water in order to avoid formation of lumps. The mixture is subsequently stirred at high speed for a period of about 1 hour, which can be carried out, for example, by means of a rotor-stator system. The glass fibers and/or mineral fibers 4 are then mixed in using a slowly rotating stirring device 15 with a low shearing action in order to damage the glass fibers and/or mineral fibers 4 as little as possible.

(6) The pulp 2 produced in this way can subsequently be poured into a casting tool 7 which is suitable for this purpose and is shown purely schematically in FIG. 1 and consists of a lower tool 8 and an upper tool 9 closing this.

(7) FIG. 2 schematically shows, likewise in greatly simplified form, an illustrative depiction of such a casting tool 7. This casting tool 7 firstly consists of a lower tool 8 and an upper tool 9. The upper tool 9 can, in the example in FIG. 2, be moved in the direction of the double arrow A and is thus suitable for opening and closing the lower tool 8. In the closed state of the casting tool 7, it has a cavity 6 whose geometry corresponds to the negative shape of the molded insulating part 1 to be produced. The special feature of the embodiment of the casting tool 7 shown here is that at least part of the wall of the cavity 6 is water-permeable. For this purpose, an outer wall 13 of an exhaust gas catalyst for a motor vehicle which is to be insulated is placed in the cavity 6 of the lower tool 8 in the example depicted in FIG. 2. This outer wall 13 is provided with a plurality of through-holes 12 which bring about thermal and acoustic insulation of the exhaust gas catalyst equipped therewith and for the purposes of the invention are utilized for removing the water from the pulp 2. Below the outer wall 13 inserted into the lower tool 8, the lower tool 8 has a plurality of holes 14.1 through which the water 3 is removed from the pulp 2. To improve the effectiveness of the removal of the water 3, a suction device 10.1 is hydrodynamically connected to the holes 14.1 in the variant depicted. The suction device 10.1 produces a subatmospheric pressure and the water 3 is drawn off from the pulp 2 in the direction of the arrow E.

(8) If the upper tool 9 of the casting tool 7 in FIG. 2 is now considered, it is conspicuous that holes 14.2 are also provided here and they serve, in the present case, to bring about an increase in pressure on the molded insulating part 1 to be produced, for which purpose the holes 14.2 in the upper tool 9 are hydrodynamically connected to a pressure device 11.1 so that, for example, compressed air can be fed in the direction of the arrow B to the upper tool 9.

(9) When the molded insulating part 1 produced in this way is finished, the casting tool 7 can be opened. For this purpose, the suction device 10.1 and the pressure device 11.1 are closed off by means of suitable control valves. An increase in pressure can now be applied to the molded insulating part 1 by means of a pressure device 11.2 in the lower tool 8 in the direction of the arrow D by introduction of compressed air, which leads to detachment of the molded insulating part 1 from the lower tool 8. At the same time, the molded insulating part 1 is drawn in by means of a suction device 10.2 in the upper tool 9 of the casting tool 7, the suction device of which produces a vacuum in the direction of the arrow C. The molded insulating part 1 which is fixed thereby can be releasably fixed in this way and be transferred to a subsequent processing unit. The holes 14.1 in the lower tool 8 and the holes 14.2 in the upper tool 9 can thus be utilized for a further use after production of the molded insulating part 1, namely fixing and transfer of the molded insulating part 1.

(10) FIG. 3 allows a look into an outer wall 13 of an exhaust gas catalyst with a molded insulating part 1 inserted therein. The outer wall 13 has a plurality of through-holes 12 and a complicated internal geometry which the molded insulating part 1 has to match in order to achieve an optimal insulating action.

LIST OF REFERENCE SYMBOLS

(11) 1 Molded insulating part 2 Pulp 3 Water 4 Glass fibers and/or mineral fibers 5 Sheet silicate 6 Cavity 7 Casting tool 8 Lower tool 9 Upper tool 10.1 Suction device 10.2 Suction device 11.1 Pneumatic pressure device 11.2 Pneumatic pressure device 12 Through-holes 13 Outer wall 14.1 Holes/microholes 14.2 Holes/microholes 15 Stirring device 16 Vessel A, B, C, D, E Direction of movement