SK282175B6 - Pipe junction and method for production of pipe junctions from polyolefin - Google Patents

Abstract

A pipe end (13) of a pipe (12) consisting of polyolefin is deformed cold, that is to say at ambient temperature, with the aid of an expanding mandrel. Once the expanding mandrel has been withdrawn, the expanded pipe end (13) and a respectively desired connecting part, or the pipe end (11) of a further pipe (10), are plugged onto one another. The pipe end (13) consisting of polyolefin experiences only a reversible deformation and, as a result of it deforming back to its original shape, forms a firm, gas-tight connection to the connecting part or to the other pipe end (11). <IMAGE>

Description

Technical field

The invention relates to a method for producing a pipe joint in which the pipe end of a polyolefin pipe is expanded and slid onto the connection part as well as the pipe joint thus produced.

BACKGROUND OF THE INVENTION

In a known analogous process, which is disclosed in DOS 38 17 442.1, such a pipe joint is produced, for example, by means of a clamping sleeve which bridges the connecting portions of the two pipes. The clamping sleeve may consist, for example, of a thermoplastic material such as cross-linked polyolefin. This sheath is joined to the end portions such that the crosslinked polyolefin after being heated above the melting point of the crystallites is deformable in the heated state and, in this heated state, can be slid onto the connecting portions after being expanded. In the same way, the pipe end of the crosslinked polyolefin pipe can be slid onto the connecting part, for example a T-piece.

Furthermore, EP-A-0 102 919 discloses a method for joining pipes and pipe joints thus produced, in which the first end of the crosslinked polyolefin pipe is expanded due to the crystalline melting temperature. A second end of the pipe is introduced into the expanded and cooled end of the pipe. Finally, the expanded pipe is warmed by the crystalline melting temperature, whereby the other end of the pipe is hot-fused to form a tight connection of the pipe ends.

The practice of carrying out this process presents some difficulties in practice, since the crosslinked polyolefin must be heated to a relatively high temperature, for example above 135 ° C in the case of the crosslinked polyolefin, and only at this temperature it has a sufficiently easy formability. Consequently, there is a need for the respective parts to be joined together in such a short time that during this time cooling does not occur below the melting point of the crystallites.

SUMMARY OF THE INVENTION

SUMMARY OF THE INVENTION The object of the present invention is to provide a pipe joint that is capable of being produced under ambient conditions and which provides a secure and tight joint, as well as a method for manufacturing a pipe joint by the aforementioned method. j. at ambient temperature.

With respect to the pipe connection, this object is achieved by the fact that it consists of the connection part and at the ambient temperature of the expanded pipe end, at the ambient temperature of the self-reshapable which is firmly and tightly connected to the end part of the connection part. which is smaller than the outer diameter of the connecting portion.

According to the invention, the method of manufacturing a pipe joint is solved by expanding the end of a pipe whose inner diameter is smaller than the outer diameter of the connecting part by means of an expanding mandrel, at ambient temperature, reversibly expanding to an inner diameter larger than the outer diameter of the connecting part. section. After removal of the expanding mandrel, the still expanded pipe end is slid onto the connecting portion, whereby the pipe end is firmly and tightly connected to the connecting portion by spontaneously reforming the reversibly expanded pipe end.

The invention is based on the surprising finding that polyofelins, in particular of medium density, high density or crosslinked polyofelins, have a sufficiently large, reversible formability even in the cold and partially crystalline state, i. j. in a heated state not exceeding the melting point of the crystallites. This means that the polyolefin is malleable by mechanical action, but in the formed state it seeks to achieve its original shape. When a sufficiently large force is used, for example by means of an expanding mandrel of a conventional type, to expand the tubes, the pipe ends of the polyolefin tubes can be reversibly expanded. Under the given conditions, at ambient temperature, the spontaneous re-deformation takes place, i.e.. j. to the original width of the pipe at a relatively low velocity so that the expanding mandrel can be removed from the expanded pipe and the still expanded pipe end slid onto the desired connecting portion. On the other hand, the rate of spontaneous reshaping is so great that there is no undesirable waiting time.

Compared to another material, polyolefins have the advantage that the extension, as long as it remains after connection to the connection portion, does not cause stress cracking.

The process according to the invention offers a particularly advantageous possibility to join polyolefin pipes, in particular medium density, high density or crosslinked polyolefins, without the use of thermal energy with any desired connecting part. In this case, a particularly rigid and tight, in particular gas-tight connection is obtained by spontaneously re-shaping the expanded pipe end. In this spontaneous re-shaping, the polyolefin adheres, in the present case, to the surface structure on the attachment portion. Examples of such surface structures which increase the bond strength are, for example, the reinforcements, notches, grooves or stiffening with which the reshaped polyolefin comes into engagement.

In connection with the method described above, it is possible, if necessary, to further secure the pipe connections made. Pipe clamps of known type can serve for this purpose. However, it is also possible to slide the clamping ring onto the pipe end of the polyolefin pipe. This clamping ring can, if it is also made of a reversibly deformable material, slide from the beginning onto the pipe end. However, it is also possible after insertion of the pipe joint to slide a non-deformable or low deformable clamping ring, for example of metal, from the pipe side onto the end of the pipe joint, for example by known hydraulic means.

Overview of the figures in the drawing

Examples of embodiments of pipe joints produced according to the invention are shown in the figures and are further explained and described in detail with reference numerals. FIG. 1 is a cross-sectional view of a pipe joint from a connection portion and a pipe end inserted according to the method of the invention; Fig. 2 is a cross-sectional view of the pipe joint of FIG. 1 with a clamping ring;

Fig. 3 is a cross-sectional view of a pipe joint according to the invention between two pipe ends.

DETAILED DESCRIPTION OF THE INVENTION

As seen in section in FIG. 1, it is possible to see the connecting part 1, which may be, for example, a straight pipe piece, an elbow or another coupling piece for connecting two pipes, but also for

Example of a triple connecting piece as a T-piece. This attached part 1 is made of a material such as metal, glass, ceramic, plastic or some other, for a given purpose, selected material. At each joining point, the connecting portion 1 is provided with a surface structure increasing the bonding strength. In the illustrated embodiment, the surface structure is formed by a reinforced end-to-end end portion 2, instead of one or more reinforcements, notches, grooves or grooves or the like.

The representation of FIG. 1 shows a pipe 3 of polyolefin, preferably of medium or high density crosslinked polyolefin. The inner diameter of the pipe 3 is smaller than the outer diameter of the connecting portion 1, as shown, may have substantially the same diameter as the inner diameter of the connecting portion 1, thereby avoiding the formation of flow resistance through the constrictions and deposits in the constrictions from the medium flowing through the connection part 1 and the pipe

3. In the embodiment of the pipe joint, the pipe end 4 is expanded so much at ambient temperature, for example by means of an expanding mandrel of the conventional type, that the inner diameter of the pipe end 4 is at least as wide as the outer diameter of the connecting portion 1 in the region of the reinforced end portion. sliding over the reinforced end portion 2 the pipe end 4 spontaneously acquires the original shape with the original dimension. As a result, the pipe end 4, as shown, adheres to the outer profile of the connecting part 1. Since the pipe end 4 initially had an inner diameter that was smaller than the outer diameter of the connecting part 1, the pipe end 4 slid along its length just over the end This results in a large, very large, very tight joint at the end between the pipe end 4 and the connecting part 1.

Fig. 2 shows a further embodiment of the previously described pipe joint, the corresponding parts being provided with the same reference numerals. In this embodiment, a clamping ring 5 is used to additionally secure the made tight joint between the pipe end 4 and the connection part 1.

This clamping ring 5 is preferably of the same material as the pipe 3. In the illustrated embodiment, the pipe 3 and the clamping ring are made of cross-linked polyethylene. The inner diameter of the clamping ring 5 is tightly fitted to the outer diameter of the pipe 3 fitted and slid onto the pipe end before making the pipe joint.

4. In the following expansion procedure, the clamping ring 5 together with the pipe end 4 is pre-expanded so that the expanded pipe end 4 together with the clamping ring 5 is pushed onto the end part 2 of the connecting part 1. Subsequent spontaneous re-deformation then to the tight connection between the pipe end 4 and the end part 2 of the connecting part 1, whereby the clamping ring 5 also contracts and additionally compresses the pipe end 4 in the region of the clamping ring 5 against the end part 2.

Fig. 3 shows a pipe joint that is formed between two pipe ends. Both tubes may be of the same or different materials; the pipes are made of cross-linked polyolefin and serve as a conduit for corrosive media. By way of example, industrial, but in particular also domestic or municipal waste water, which requires particularly corrosion-resistant pipe materials. For this purpose, crosslinked polyolefin pipes have been proven in practice.

In the illustrated embodiment, both tubes have the same outer and inner diameters. However, it does not matter that the same pipe joints can be produced in the present case also between tubes of different diameters, provided that the differences in internal diameters so connected do not cause unacceptable flow resistances and deposits. The first pipe 10 has a first pipe end 11, the second pipe 12 has a second pipe end 13. It can be seen that the inner diameter of the second pipe end 13 is widened and this expanded second pipe end 13 is slid onto the first pipe end 11 of the first pipe 10. This extension For example, as in the present embodiment, it is carried out with a suitable expanding mandrel at ambient temperature and is subject to the spontaneous re-deformation described above, by means of which the expanded pipe end 13 seeks to regain its previous state. The large-area, tight abutment between the two pipe ends 11 and 13 also forms a tight pipe connection here, which, due to the corrosion resistance of the material against said waste water, will be tight even during prolonged use.

As in FIG. 2 showing an example of manufacture, here again the connection can be additionally secured by a clamping ring; however, care must be taken that, under the pressure of such a clamping ring, there is no unacceptable change in the shape of the first pipe end 11, which constitutes a flow resistance of the flowing waste water or gives rise to waste water deposits in the area of the joint. Instead of the clamping ring, a fastening means can also be used in the present case to additionally secure the connection point.

Crosslinked polyolefin pipes are also used for this reason in sewage technology, since in this way safe, self-sealing joints between smooth pipes can be easily produced. A further advantage is that pipes 10 and 11 made by a continuous process can be laid in one piece without the need for special elbows or other connecting parts so that the pipes can be laid in the desired position. It is therefore only necessary to make connections at the inlet and outlet points between the pipes.

Claims (11)

PATENT CLAIMS Method for producing a clamping joint comprising an end (4) of a cross-linked polyolefin tube and a connecting portion (1) having a surface structure, wherein the end (4) of cross-linked polyolefin tube having an inner diameter less than the outer diameter of the connecting part (1) is widened by means of expanding darkness at ambient temperature to an inner diameter which is larger than the outer diameter of the connecting part (1) and after removal of the expanding darkness the end (4) of the pipe (3) is the coupling part (1) is pushed together and then shrunk together by shrinking the expanded pipe end (4), characterized in that the pipe end (4) is provided with a clamping ring (5) made of material expandable and spontaneously at ambient temperature By means of a deformable and together with a clamping ring (5), it is firmly and tightly connected to the connecting part (1) by spontaneous deformation at ambient temperature. Method according to claim 1, characterized in that the clamping ring (5) consists of crosslinked polyolefin. Method according to claim 1 or 2, characterized in that the widened pipe end (4) shrinks to the end part (2) of the connecting part (1) provided on the outer periphery with a surface structure. Method according to claim 3, characterized in that the surface structure is formed from a thickened end-tapered end portion (2). 5. Clamping joint pipe connection consisting of a connecting part (1) with a surface structure and 2826 the end (4) of the cross-linked polyolefin pipe (3) having an inner diameter smaller than the outer diameter of the connecting part (1), the end (4) of the pipe (3) being spontaneously deformed to the connecting part (1), characterized in that the pipe end (4) is provided with a clamping ring (5) of a material, extensible at ambient temperature and self-deformable. Pipe joint according to claim 5, characterized in that the clamping ring (5) consists of the same material as the pipe (3). Pipe joint according to claim 5 or 6, characterized in that the surface structure is formed on the end portion (2) of the connecting portion (1) and overlaps over its outer periphery. Pipe joint according to claim 7, characterized in that the surface structure is formed from a thickened end-tapered end portion (2). A clamp-like pipe joint comprising a first pipe end (11) of a first crosslinked polyolefin pipe (10) and a second pipe end (13) of a second crosslinked polyolefin pipe (12) having an inner diameter smaller than the outer diameter of the first a pipe end (11), wherein at the ambient temperature of the extension the pipe end (13) is spontaneously connected to the first pipe end (11), characterized in that the second pipe end (13) is provided with a clamping ring formed of material , at ambient temperature expandable and self-deformable. Pipe joint according to claim 9, characterized in that the clamping ring (5) consists of the same material as the second pipe (12). A pipe joint according to claim 9 or 10, characterized in that the first and second pipes (10, 12) are formed as plain pipes.