Connecting element and pipe connection comprising the same

Abstract

The present invention relates to a connecting element (1) for producing a pipe connection (6) between the connecting element (1) and a plastic pipe (7) or a metal-plastic composite pipe by using axial pressing technology, wherein the connecting element (1) has at least one support body (2, 2a) provided with circumferential external ribs (3, 3a, 3b) for press-fitting an expanded end (8) of the pipe (7) onto, and comprises at least one circumferential collar (5, 5a), wherein the connecting element (1) between the circumferential collar (5, 5a) and the nearest circumferential external rib (3b) to said circumferential collar (5, 5a) further comprises a pre-stop (4, 4a) for limiting the sliding onto of the expanded end (8) of the pipe (7), wherein the distance between the edge of the pre-stop (4, 4a) facing the circumferential external ribs (3, 3a, 3b) and the edge of the circumferential collar (5, 5a) facing the pre-stop (4, 4a) is 0.10 times to 0.30 times the length of the support body (2, 2a). Furthermore, the present invention relates to a pipe connection (6) between an expanded end (8) of an all-plastic pipe (7) or of a plastic composite pipe (7) and a connecting element (1), comprising an expanded end (8) of an all-plastic pipe (7) or of a plastic composite pipe (7); and a connecting element (1) according to the present invention.

Claims

1. Connecting element for producing a pipe connection between the connecting element and a plastic pipe or a metal-plastic composite pipe by using axial pressing technology, wherein the connecting element has at least one support body provided with circumferential external ribs for press-fitting an expanded end of the pipe onto, and comprises at least one circumferential collar, wherein the connecting element between the circumferential collar and the nearest circumferential external rib to the said circumferential collar further comprises a pre-stop for limiting the sliding onto of the expanded end of the pipe, wherein the distance between the edge of the pre-stop facing the circumferential external ribs and the edge of the circumferential collar facing the pre-stop is 0.10 times to 0.30 times the length of the support body.

2. Connecting element according to claim 1, wherein the circumferential collar is connected with the pre-stop via a plurality of bridges or in that the pre-stop is designed in a stepped arrangement to the circumferential collar as an integral component thereof.

3. Connecting element according to claim 1 or 2, wherein the external diameter of the pre-stop is 1.1 times to 1.5 times the external diameter of the circumferential external rib having the largest external diameter.

4. Connecting element according to claim 1, wherein the distance between the pre-stop and the nearest circumferential external rib of which pre-stop is 0.10 times to 0.50 times the length of the support body.

5. Connecting element according to claim 1, wherein the width of the circumferential collar equals 0.050 times to 0.20 times the length of the support body.

6. Connecting element according to claim 1, wherein the external diameter of the circumferential collar equals 1.1 times to 2.0 times the external diameter of the circumferential external ribs having the largest external diameter.

7. Connecting element according to claim 1, wherein at least one of the circumferential external ribs has a saw tooth-like cross section and at least one of the circumferential external ribs has a substantially rectangular cross section.

8. Connecting element according to claim 1, wherein the distance between the edges of two adjacent circumferential external ribs facing the collar equals 0.10 times to 0.50 times the length of the support body.

9. Connecting element according to claim 1, wherein the external diameter of each circumferential external rib independently equals 1.03 times to 1.3 times the external diameter of the base area of the support body.

10. Connecting element according to claim 1, wherein the length of the support body equals 0.60 times to 2.0 times the external diameter of the circumferential external rib with the largest external diameter.

11. Pipe connection between an expanded end of an all-plastic pipe or of a plastic composite pipe and a connecting element, comprising: an expanded end of an all-plastic pipe or of a plastic composite pipe; and a connecting element according to claim 1.

12. Pipe connection according to claim 11, wherein the pipe connection comprises a sliding sleeve made of elastically deformable polymer material axially slid onto the expanded end.

13. Pipe connection according to claim 11, wherein the end of the sliding sleeve facing the circumferential collar protrudes beyond the edge of the pre-stop facing the circumferential external rib.

14. Pipe connection according to claim 11, wherein the ratio of the height of the pre-stop to the wall thickness of the pipe ranges from 0.40 to 1.0 and preferably from 0.50 to 0.98.

15. Pipe connection according to claim 11, wherein the following applies to the expansion ratio R(exp) of the sliding sleeve connection: 0.05<R(exp)=[D(max)/D(internal)]1<0.3 wherein D(max) stands for the maximum external diameter of the circumferential external ribs and D(internal) stands for the internal diameter of the pipe.

16. Pipe connection according to claim 15, wherein the pipe is an all-plastic pipe and the expansion ratio R(exp) of the sliding sleeve connection ranges from 0.10 to 0.35, preferably from 0.15 to 0.25, or the pipe is a metal-plastic composite pipe (and the expansion ratio R(exp) of the sliding sleeve connection ranges from 0.05 to 0.25, preferably from 0.10 to 0.20.

17. Pipe connection according to claim 11, wherein the internal surface of the sliding sleeve has an average roughness value Ra in a range of 1 m to half of the average wall thickness of the sliding sleeve.

18. Pipe connection according to claim 11, wherein the internal surface of the sliding sleeve has a plurality of macroscopic irregularities the depth of which does not exceed half the average wall strength of the sliding sleeve.

Description

[0032] The following is intended to explain the invention in detail with reference to the embodiments shown in the figures. The figures show in:

[0033] FIG. 1 a side view of a connecting element for use in a pipe connection according to an embodiment of the present invention;

[0034] FIG. 2 is a side view of a pipe connection according to an embodiment of the present invention, in which a plastic pipe is slid onto a support body of the connecting element illustrated in FIG. 1, wherein the end of the pipe and the sliding sleeve are shown in section;

[0035] FIG. 3 is a side view of a connecting element for use in a pipe connection according to a further embodiment of the present invention; and

[0036] FIG. 4 is a side view of a connecting element for use in a pipe connection according to a further embodiment of the present invention.

[0037] FIG. 1 shows a side view of a connecting element 1 according to an embodiment of the present invention. The connecting element 1 is a connecting piece having two support bodies 2, 2a, wherein each of the support bodies 2, 2a in the embodiment shown in FIG. 1 has three circumferential external ribs 3, 3a, 3b. Said three circumferential external ribs 3, 3a, 3b extend in an axial direction, beginning at the open end of the connecting element 1, and are arranged in such a way that two consecutive saw-tooth-shaped circumferential external ribs 3, 3a are followed by a circumferential external rib 3b with a substantially rectangular cross section. A pre-stop 4, 4a connects with each of the two support bodies 2, 2a. Furthermore, the connecting element 1 has a circumferential collar 5, 5a for each support body 2, 2a, which closes off the respective support body 2, 2a.

[0038] The geometry of the connecting element 1 according to the present invention and a pipe connection 6 according to the present invention which comprises the connecting element 1 are described in detail in the following with reference to the left support body 2 in FIG. 1, wherein it is understood that such explanations also apply to the right support body 2a in FIG. 1 as well as to further existing support bodies possibly present in other embodiments accordingly.

[0039] FIG. 2 shows a side view of an embodiment of a pipe connection 6 according to the invention comprising the connecting element 1 shown in FIG. 1. A sliding sleeve 9, shown in a sectional view in FIG. 2, is slid therein beyond the expanded end of the pipe 8 of the all-plastic or metal-plastic composite pipe 7 slid onto support body 2 and extending to the pre-stop 4 as a maximum, said pipe 7 also being shown in sectional view in FIG. 2, in the direction of the circumferential collar 5 of the connecting element. As the pre-stop 4 is spaced from the circumferential collar 5, a hollow space is formed between the pre-stop 4 and the circumferential collar 5. Said hollow space allows a bending of the section of the sliding sleeve 9 protruding beyond the end of the pipe 8 in the direction of the support body 2. This results in a mechanical fixing of the sliding sleeve 9 and thus an increased stability of the pipe connection 6 according to the present invention. In the embodiment of the connecting element 1 according to the present invention shown in FIG. 1 the distance between the circumferential collar 5 of the connecting element 1 according to the present invention and the associated pre-stop 4 is 0.20 times the length of the support body 2. In alternative embodiments of the connecting piece 1 according to the present invention the distance between the pre-stop 4 and the circumferential collar 5 can equal 0.10 times to 0.30 times the length of the support body 2. As used herein, the term length of the support body 2 in each case refers to the distance between the open end of the support body 2 of the connecting element 1 and the circumferential collar 5. The external diameter of the pre-stop 4 in the shown embodiment of the connecting element 1 according to the present invention is 1.25 times the external diameter of the circumferential external ribs 3, 3a, 3b having the largest external diameter. In alternative embodiments the external diameter of the pre-stop 4 can equal 1.1 times to 1.5 times the external diameter of the circumferential external rib 3, 3a, 3b with the largest external diameter. If the external diameter of the pre-stop 4 is within the stated range, the pre-stop 4 constitutes a sufficiently large obstacle for the expanded end of the pipe 8 without impairing the stability of the pipe connection 6 according to the present invention. In the embodiment shown the ratio of the height of the pre-stop 4 over the base area of the support body 2 to the wall thickness of the all-plastic or metal-plastic composite pipe 7 is 0.75 and preferably ranges from 0.40 to 1.0.

[0040] In the embodiment of the connecting element 1 according to the present invention shown in FIG. 1 and FIG. 2 the distance between pre-stop 4 of the connecting element 1 according to the present invention and the nearest circumferential external rib 3b to the latter is 0.18 times the length of the support body 2. This allows the sliding sleeve 9 in the pipe connection 6 according to the present invention to be pushed more strongly into the expanded end of the pipe 8 of the all-plastic or metal-plastic composite pipe slid onto the support body 2 than via the section at which the circumferential external ribs 3, 3a, 3b are arranged (FIG. 2). This results in further increased stability of the pipe connection 6 according to the present invention. In alternative embodiments of the connecting piece 1 according to the present invention the distance between the pre-stop 4 and the nearest circumferential external rib 3b to the latter can be 0.10 times to 0.50 times the length of the support body 2. The wall thickness or width of the circumferential collar 5 equals 0.11 times the length of the support body 2, wherein in alternative embodiments of the connecting piece 1 the width of the circumferential collar 5 can be 0.050 times to 0.20 times the length of the support body.

[0041] The external diameter of the circumferential collar 5 is 1.4 times the external diameter of the circumferential external ribs 3, 3a, 3b, which have the same maximum external diameter in the embodiment shown. The risk of the press-fit tool slipping off the circumferential collar 5 during pressing is thus low, thereby resulting in the resistance of the circumferential collar 5. In alternative embodiments of the connecting piece 1 of the present invention the external diameter of the circumferential collar 5 is 1.0 times to 2.0 times the external diameter of the circumferential external rib 3, 3a, 3b with the largest external diameter. The length of the support body 2 is 1.4 times the external diameter of the circumferential external ribs 3, 3a, 3b, wherein in alternative embodiments of the connecting piece 1 according to the present invention the length of the support body 2 is 0.60 times to 2.0 times the external diameter of the circumferential external rib 3, 3a, 3b with the largest external diameter. The connecting element 1 according to the present invention thus has good resilience to bending stress with reasonable material expense. The external diameter of the circumferential external ribs 3, 3a, 3b measures 1.1 times the external diameter of the base area of the support body 2. This allows the circumferential external ribs 3, 3a, 3b of the connecting element 1 according to the present invention in a pipe connection 6 according to the present invention to be pushed far enough into the end of the pipe 8 slid onto the support body 2 to ensure a secure and tight fit of the end of the pipe 8 on the support body 2 with reasonable material expense. In alternative embodiments of the connecting element 1 according to the invention the maximum external diameter of the circumferential external ribs 3, 3a, 3b is 1.03 to 1.3 times the external diameter of the base area of the support body 2. Here, the circumferential external ribs 3, 3a, 3b can have differing external diameters, although it is preferred that the circumferential external ribs 3, 3a, 3b have the same external diameter. The distance between the two saw-tooth-shaped circumferential external ribs 3, 3a is 0.25 times the length of the support body 2, while the distance between the saw-tooth-shaped circumferential external rib 3a and circumferential external rib 3b with a substantially rectangular cross-section is 0.2 times the length of the support body 2, always measured from the edges facing the circumferential collar. This allows the circumferential external ribs 3, 3a, 3b of the connecting element 1 according to the present invention to be pressed far enough into the end of the pipe 8 press-fitted onto the support body 2 to ensure a securely fitting seal. However, it is preferred if the three circumferential external ribs 3, 3a, 3b are distributed as equally as possible on the corresponding section of the support body 2. These advantages allow the distance between two circumferential external ribs 3, 3a, 3b in alternative embodiments of the connecting element 1, always measured from the edges facing the circumferential collar, to equal 0.10 times to 0.50 times the length of the supporting body 2 as well.

[0042] The connecting element 1 according to the present invention shown in FIG. 1 is designed in mirror symmetry to a level running down the middle between the two circumferential collars 5, 5a and perpendicularly to the axis of the connecting element 1. Accordingly, the comments made with reference to the support body 2 thus apply analogously to support body 2a.

[0043] The connecting element 1 according to the present invention in the embodiment shown in FIG. 1 is a component made of polyphenyl sulfone (PPSU). Also usable in alternative embodiments of the connecting element 1 according to the present invention are polypropylene and glass fibre reinforced polypropylene, polyamides and glass fibre reinforced polyamides, polyvinylidene fluoride (PVDF), polyether sulfone (PES), polysulfone (PSU), polyphenyl sulphide (PPS), acrylonitrile-butadiene-styrene copolymer (ABS) and polyester carbonate (PESC), as well as copolymers and blends of said polymers, wherein said polymer materials can also be used fibre reinforced, in particular glass fibre reinforced, or metallic materials, such as brass, in particular Ecobrass, red brass and stainless steel.

[0044] Pipe 7 according to this embodiment of the present invention is an all-plastic pipe 7 made of cross-linked polyethylene (PE-X, in particular PE-Xa, PE-Xb and PE-Xc). As an alternative, all-plastic pipes made of other materials as well as plastic composite pipes and metal-plastic composite pipe can also be used as pipe 7 in other embodiments of the present invention. Preferred, however, when using plastic composite pipes and metal-plastic composite pipes is a layer of cross-linked polyethylene (PE-X), in particular PE-Xa, PE-Xb and PE-Xc as the layer facing the internal diameter of pipe 7.

[0045] A further pipe 7 can be connected to the second support body 2a according to the invention by a pipe connection 6 according to the invention. The further pipe 7 can have an identical or different construction to the pipe 7 of the support body 2.

[0046] The sliding sleeve 9 used to fix the expanded end of the pipe 8 onto the support body 2 is a sleeve made of cross-linked polyethylene (PE-X, in particular PE-Xa, PE-Xb and PE-Xc) in the embodiment shown in FIG. 1, which has a constant cross section over its entire length. Alternatively, sliding sleeves 9 made of other materials, in particular polyvinylidene fluoride (PVDF), can also be advantageously used. The sliding sleeve 9 in this embodiment has an internal surface with an average roughness value R.sub.a in a range of 4 m, wherein the roughness of the internal surface in alternative embodiments of the sliding sleeve 9 preferably ranges from 1 m to half of the average wall thickness of the sliding sleeve 9. An increased roughness on the internal surface of the sliding sleeve 9, compared with sliding sleeves with smooth internal surfaces, leads to a reduction in the force needing to be exerted for axially sliding the corresponding sliding sleeve 9 onto the expanded end of the pipe 8 with inserted support body 2. At the same time, an internal surface of the sliding sleeve 9 with increased roughness has a lower tendency to relative motion of the sliding sleeve 9 on the expanded end of the pipe 8, in particular in the event of thermal cycling.

[0047] In order to generate the pipe connection 6 according to the present invention, the sliding sleeve 9 is initially slid over the end 8 of the plastic pipe 7. An expansion tool is then inserted in the end of the plastic pipe 8 and the plastic pipe 7 is expanded at one end by means of an expansion tool. Thereupon, the support body 2 of the connecting element 1 according to the present invention is inserted in the expanded end 8 of the plastic pipe 7 until the expanded end 8 of the plastic pipe 7 is approximately attached to the pre-stop 4. The expanded end 8 of the plastic pipe 7 contracts due to the memory effect of the raw material, wherein the plastic material of the plastic pipe 7 presses into the external contour of the support body 2 of the connecting element 1 according to the present invention. The sliding sleeve 9 is then slid in an axial direction onto the expanded end 8 of the plastic pipe 7 with inserted support body 2 by a suitable press-fit tool in such a way that the expanded end 8 of the plastic pipe 7 is fixed on the support body 2. Further plastic pipes 7 or metal-plastic composite pipes 7 may now be connected in the same way to further support bodies 2a, thereby forming a pipe connection 6 according to the present invention.

[0048] In the embodiment shown in FIG. 2, the expansion ratio is approximately 0.25. This value is particularly preferred for a pipe connection 6 between a connecting element 1 and an all-plastic pipe 7, while a value of approximately 0.15 is particularly preferred for a connection between a connecting element 1 according to the present invention and a metal-plastic composite pipe 2.

[0049] In turn, FIG. 3 shows a side view of a further preferred embodiment of a connecting element 1 according to the present invention to form a pipe connection 6 according to the present invention. The connecting element of the present invention according to FIG. 3 differs from the connecting element 1 shown in FIG. 1 merely due to the fact that the two pre-stops 4, 4a are each connected with the associated circumferential collar 5, 5a via bridges 10 formed thereon in one-piece. This results in a higher mechanical stability of the connecting element 1 according to the present invention. With regard to further properties of the connecting element 1 according to the present invention, as well as of the pipe connection 6 according to the present invention formed therewith, the comments on FIG. 1 and FIG. 2 also apply to the connecting element 1 according to FIG. 3.

[0050] FIG. 4 shows a side view of a connecting element 1 according to the present invention for forming an pipe 6 according to a further preferred embodiment of the present invention. The connecting element of the present invention according to FIG. 4 differs from the connecting element 1 of the present invention shown in FIG. 1 solely by the fact that each pre-stop 4, 4a is configured attached to the associated circumferential collar 5, 5a. The respective pre-stop 4, 4a thus forms an integral component of the associated circumferential collar 5, 5a. In this embodiment the pre-stop 4, 4a and the associated circumferential collar 5, 5a of a supporting body form a two-stage stepped arrangement. In this manner, it is achieved a higher mechanical stability of the connecting element 1 of the present invention. With regard to further properties of the connecting element 1 of the present invention, as well as of the pipe connection 6 of the invention designed therewith, the comments on FIG. 1 and FIG. 2 also apply to the connecting element 1 according to FIG. 4.

[0051] The connecting element 3 of the pipe connection 6 according to the present invention in the embodiments shown in FIG. 1, FIG. 2 and FIG. 3 is a pipe connector with two pipe connection sections or support bodies. Alternatively, the connecting element 3 according to the present invention can be configured as a connecting piece, connection bracket, multiple distributor, t-piece, wall t-piece, wall bracket, system transition, transition piece and angled transition piece, each possibly designed with at least one internal and/or external thread or threadless.

[0052] The present invention has been described in detail with reference to the embodiments of the present invention shown in the figures. It is understood that the present invention is not limited to the embodiments shown, but that the scope of the present invention results from the attached claims.