PIPE-CONNECTION MOULDED PART HAVING THERMAL INSULATION AND METHOD OF PRODUCING THE PIPE-CONNECTION MOULDED PART

Abstract

A pipe-connection moulded part comprising an inner pipe part, an insulating layer and an outer casing of plastic, wherein the outer casing and the insulating layer are formed from the same plastic, for example polyurethane. A method of producing the pipe-connection moulded part is also proposed.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

An exemplary embodiment of the invention is described with reference to the figures. In the drawing:

FIG. 1 shows a section through a pipe-connection moulded part according to the invention,

FIG. 2 shows a section through a mould for producing the pipe-connection moulded part from FIG. 1 according to a first method step, and

FIG. 3 shows a section through a further mould for producing the pipe-connection moulded part from FIG. 1 according to a following method step.

DETAILED DESCRIPTION

In FIG. 1, a pipe-connection moulded part 1 having thermal insulation is shown sectioned along the centre line. The pipe-connection moulded part 1 from FIG. 1 is assembled, for example, from a main pipeline 2 having a pipe branch 3. As viewed from inside to outside, the pipe-connection moulded part 1 is composed of an inner pipe part 4, for example made of an acrylonitrile-butadiene-styrene copolymer (=ABS), an insulating layer 7 and an outer casing 8.

The insulation of the pipe-connection moulded part 1 is composed of a first polyurethane foam layer 7 which is produced from a closed-cell foam and of a second polyurethane layer 8 which is produced from a pourable polyurethane system. The outer casing 8 may also be produced from another plastic system pourable under as low a pressure as possible. It is in particular important here that the outer casing, during the production, for example by casting, does not compress and does not damage the inner insulating layer, that is to say the first polyurethane foam layer 7. The outer casing 8 should exert as little pressure as possible on the insulating layer 7. The outer casing 8 may also be firmly connected to the first polyurethane foam layer 7 subsequently by a shrinkage process. The polyurethane foam layers 7, 8 are firmly adhesively bonded to one another and are connected to the inner pipe part 4. The pipe-connection moulded part 1 is produced in one piece and has high rigidity.

The pipe-connection moulded part 1 according to two successive method steps of the production method is shown sectioned in FIGS. 2 and 3. The pipe-connection moulded part 1 is produced in a combined foaming and casting process in a first mould 9. An inner pipe part 4 having a pipe branch 3 is inserted into the mould 9. The inner pipe part 4 may also be made of metal instead of a plastic. The clearance space between the inner pipe part 4 and the inner wall of the mould 9 is filled and foamed in a first method step with a reactive polyurethane foam forming closed cells.

Then, after the first polyurethane foam layer 7 has fully reacted, the pipe-connection moulded part 1 is put into a second mould 9′ which is only slightly larger than the first mould 9. In the second mould 9′, a second layer 8 of a polyurethane casting compound or of another non-foaming plastic casting system or of a plastic casting system which does not foam to a considerable degree is inserted into the mould 9′. The material for the casting compound of the outer casing 8 is selected in such a way that the outer casing 8 exerts only a small pressure on the insulating layer 7. Instead of a polyurethane system, a poly epoxy system or another thermoplastic system, for example, may also be selected. In principle, if there is a slight difference in the dimensions of the first and the second mould 9, 9′, a single mould having adjustable inner walls is also feasible.

The first polyurethane foam layer 7 and the second polyurethane casting compound 8 join together by adhesion and form an insulating casing 5 which ensures good thermal insulation on the one hand and sufficient rigidity and strength of the pipe-connection moulded part 1 on the other hand. The first polyurethane foam layer 7 is, for example, two to six times as thick as the outer casing 8 consisting of a polyurethane casting compound 8 or of a casting resin. The insulating layer 7 of polyurethane foam has, for example, a density which is substantially less than 10% of the density of the outer casing 8 consisting of the polyurethane casting compound.

The pipe-connection moulded part 1 is used, for example, in pipeline systems for refrigerants. The pipe-connection moulded part 1 is distinguished by very simple production, for the same unit can be used for the production of the insulating layer and the outer casing. As low a thermal expansion as possible is achieved through the use of the same materials for insulating layer and casing. The outer casing is watertight and the pipe-connection moulded part has high rigidity. In particular in pipe-connection moulded parts having pipe elbows or pipe branches, this production method saves more time and labour than previous production methods. Orienting the inner pipe 4 with respect to the outer casing 8 and/or delivery in a further mould are dispensed with. The shrinking of the heat-shrinkable tubing on a shrink-fit unit is dispensed with.

Claims

1. Pipe-connection moulded part comprising an inner pipe part, an insulating layer and an outer casing of plastic, wherein the outer casing and the insulating layer are formed of the same material.

2. Pipe-connection moulded part according to claim 1, wherein the material is polyurethane.

3. Pipe-connection moulded part according to claim 1, wherein the insulating layer is in contact with the inner pipe part, is connected to an outer side of the inner pipe part and is formed as a foam.

4. Pipe-connection moulded part according to claim 1, wherein the insulating layer is in contact with an inner pipe part, is connected to the outer side of the inner pipe part (4) and is formed as a closed-cell polyurethane foam.

5. Pipe-connection moulded part according to claim 4, wherein the outer casing is formed of a pourable material compatible with the insulating layer.

6. Pipe-connection moulded part according to claim 4, wherein the outer casing is in contact with the insulating layer, is connected to an outer side of the foam insulating layer and is formed of a pourable foam material.

7. Pipe-connection moulded part according to claim 1, wherein the outer casing is in contact with the insulating layer, and is connected to an outer side of the foam insulating layer.

8. Pipe-connection moulded part according to claim 1, wherein the outer casing is in contact with the insulating layer, is connected to an outer side of the insulating foam layer and is formed of a non-foamed polyurethane material.

9. Pipe-connection moulded part according to claim 4, wherein the inner pipe part is formed from an acrylonitrile-butadiene-styrene copolymer (=ABS).

10. Pipe-connection moulded part according to claim 4, wherein the inner pipe part is formed from a plastic selected from the group consisting of polyethylene, polypropylene and polyvinylchloride.

11. Pipe-connection moulded part according to claim 4, wherein the pipe-connection moulded part has at least one pipe branch.

12. Pipe-connection moulded part according to claim 4, wherein the pipe-connection moulded part has at least one pipe elbow.

13. Method of producing a pipe-connection moulded part of claim 3 comprising the steps of: a) inserting the inner pipe part into a first mould,b) foam-encapsulating the inner pipe part with a first insulating layer, consisting of a foam system,c) inserting the foam-encapsulated inner pipe part with the insulating layer in a second mould which is slightly larger than the first mould, andd) casting an outer casing around the insulating layer, said outer casing consisting of a pourable, non-foaming material system compatible with the insulating layer for producing a low internal tool pressure, without the insulating layer being damaged or compressed by the outer casing in the process.

14. Method of producing a pipe-connection moulded part according to claim 13, wherein the method steps b), c) and d) are carried out successively in the same mould.

15. Method of producing a pipe-connection moulded part according to claim 13, wherein the foam system is a closed-cell polyurethane foam system.