Electrofusion Tape

Abstract

Electrofusion tape and method for the production thereof for welding together with plastics pipes in particular for use in a fixed-point fastening, consisting of a jacket element preferably of an electrically insulating plastics material, at least one heating element of electrically conductive plastics material and at least two contact elements for supplying electricity to the heating element, wherein the jacket element and the heating element take the form of tapes, wherein the jacket element surrounds the heating element at least in part, wherein the contact elements are arranged in the mutually opposing marginal regions of the heating element and extend parallel to one another along the heating element.

Claims

1. An electrofusion tape for welding plastics pipes comprising a jacket element of an electrically insulating plastics material, at least one heating element of electrically conductive plastics material and at least two contact elements for supplying electricity to the heating element, wherein the jacket element and the heating element take the form of tapes, wherein the jacket element surrounds the heating element at least in part, wherein the contact elements are arranged in mutually opposing marginal regions of the heating element and extend parallel to one another along the heating element.

2. The electrofusion tape according to claim 1, wherein the specific conductivity of the contact elements is higher than the specific conductivity of the heating element, preferably at least ten times, especially preferably at least one hundred times, higher.

3. The electrofusion tape according to claim 1, wherein the heating element of electrically conductive plastics material has a specific electrical resistance of 0.1100 [cm], preferably of 0.110 [cm].

4. The electrofusion tape according to claim 1, wherein the contact elements are made of metal, preferably of copper or of endless carbon fibre or of an electrically conductive plastics compound with carbon nanotubes, graphite, graphene or with a metallic filler.

5. The electrofusion tape according to claim 1, wherein the contact elements take the form of wire or wire braid.

6. The electrofusion tape according to claim 1, wherein the jacket element and the heating element are manufactured on the basis of the same grade of plastics material, preferably on the basis of a thermoplastic, a thermoplastic polyolefin being especially preferred.

7. The electrofusion tape according to claim 1, wherein the heating element is arranged form-fittingly in the jacket element.

8. The electrofusion tape according to claim 1, wherein the electrofusion tape has a wraparound guide or is configured as such and the heating element is guided by the jacket element, wherein the heating element is gripped around at least in part by the jacket element.

9. The electrofusion tape according to claim 1, wherein the heating element is displaceable neither sideways nor transversely of the longitudinal direction of the tape, the heating element preferably being arranged so as to be displaceable in the jacket element solely in the longitudinal direction of the tape.

10. The electrofusion tape according to claim 1, wherein in the cross-section of the electrofusion tape the width or diameter of the contact element is less than or equal to the thickness of the heating element in the region of the contact face between contact element and heating element.

11. The electrofusion tape according to claim 1, wherein the jacket element and the heating element have a dovetail guide or a T-slot guide or take the form of a dovetail guide or T-slot guide.

12. The electrofusion tape according to claim 1, wherein the heating element has anchors for connection with the jacket element.

13. The use of an electrofusion tape according to claim 1 in a fixed-point fastening for a pipe, wherein the electrofusion tape is preferably manufactured as endless tape and may be cut individually to length and is encompassed by a pipe clamp of the fixed-point fastening or the pipe clamp is arranged axially offset relative to the electrofusion tape on the pipe and serves as an axial limit stop.

14. A method for producing an electrofusion tape according to claim 1, wherein the heating element with the contact elements arranged therein and the jacket element are produced separately by extrusion and the heating element and the jacket element are fitted together after extrusion or in that the heating element with the contact elements arranged therein and the jacket element are co-extruded together.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Exemplary embodiments of the invention are described with reference to the figures, the invention not being limited solely to the exemplary embodiments. In the figures:

[0030] FIG. 1 shows a cross-section through an electrofusion tape according to the invention,

[0031] FIG. 2 shows a cross-section through an electrofusion tape according to the invention,

[0032] FIG. 3 shows a cross-section through an electrofusion tape according to the invention,

[0033] FIG. 4 is a three-dimensional view of an electrofusion tape according to the invention,

[0034] FIG. 5 is a three-dimensional view of an electrofusion tape according to the invention,

[0035] FIG. 6 shows a cross-section through an electrofusion tape according to the invention, wherein the contact element has a round cross-section and

[0036] FIG. 7 shows a cross-section through an electrofusion tape according to the invention, wherein the contact element has an angular cross-section,

[0037] FIG. 8 is a view of a possible fixed-point fastening in which the fixed-point fastening surrounds the electrofusion tape and

[0038] FIG. 9 is a view of a possible fixed-point fastening in which the fixed-point fastening is arranged axially offset.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0039] FIGS. 1-3 show cross-sections of an electrofusion tape 1 according to the invention each with different shapes of the connection configuration or of the wraparound guide which serves to ensure that the heating element 3 is guided at the sides and the top and bottom in the jacket element 2 and cannot readily or independently become detached from the jacket element 2. FIG. 1 shows a wraparound guide which takes the form of a T-slot guide. This enables displacement of the heating element 3 in the jacket element 2 along the length of the tape 5 but prevents lateral and also relative upwards and downwards displacement and independent mutual separation of the two elements 2, 3. The possibility of relative displacement of the elements 2, 3 along the tape length 5 allows the fusion tape 1 to be placed around any size pipe diameter since, due to the relative displacement, the fusion tape 1 is flexible or more bendable in application. A co-extruded electrofusion tape 1 suffers slight losses in flexibility or pliability with regard to its fusion of the jacket element 2 with the heating element 3, but due to the thin configuration of the elements good pliability is still present. FIG. 2 likewise shows a wraparound guide, the further figures also showing different possible configurations of such guides, wherein it goes without saying that still further configurations are possible.

[0040] In the cross-sections shown, the jacket element 2 encloses the heating element 3 at least in part. It goes without saying that complete enclosure is also conceivable, wherein the jacket element 2 is then preferably of thin configuration at the bottom of the heating element 3 in order to transmit the heat arising in the heating element 3 by thermal conduction rapidly through the jacket material to the tube and to fuse therewith.

[0041] The heating element 3 to this end comprises a conductive plastics material which allows current flow from one contact element 6 to another, whereby the heating takes place as well as fusing on and together of the plastics materials of the heating element 3, the jacket element 2 and the pipe on which the fusion tape 1 is fastened.

[0042] Since the current flow is achieved exclusively through the conductive plastics material and without additional wires or stranded wires apart from the contact element 6, the heating element 3 is not impaired in its flexibility, which is likewise of benefit to diameter-independent application and thus allows fastening whatever the diameter.

[0043] The contact elements 6 are arranged in the marginal region 4 of the heating element 3 and serve in supplying power to the heating element 3.

[0044] As a further alternative possible configuration, FIG. 3 shows anchors 9 which ensure mutual engagement of the heating element 3 and the jacket element 2.

[0045] As indeed with the other possible types of connection, there is also the possibility here of mutual displacement in the longitudinal direction 5 of the tape in that a generous gap is present in the jacket element 2 between anchor 9 and receiving contour, which as already mentioned ensures high tape 1 flexibility.

[0046] FIG. 4 shows a dovetail guide, and also that different configurations of the outer surface of the jacket element 2 may be present. That is to say, the outer face may for example be slightly recessed in the middle relative to the marginal regions, which may then serve as a limit stop in order to limit axial displacement or as a defined region for accommodating a tape or hook and loop tape which serves in mounting the electrofusion tape 1 prior to welding to the tube. It goes without saying that straight faces or other contours of the outer face of the jacket element 2 are also conceivable.

[0047] The fusion tape 1 is preferably produced by extrusion, wherein the electrofusion tape 1 may also be co-extruded and the heating element 3 and the jacket element 2 thereby fused together but, as already mentioned, they are here regarded as being of multipart construction also due to the different plastics compositions exhibited by the heating element and the jacket element. The contact element 6 or the contact elements 6 are likewise introduced during extrusion or co-extrusion. FIG. 5 shows a three-dimensional view of a fusion tape 1 according to the invention, wherein the heating element 3 projects slightly out of the jacket element 2 so it can be seen. The jacket element 2 and the heating element 3 are based on the same plastics material, preferably a thermoplastic, especially preferably a thermoplastic polyolefin.

[0048] It is additionally advantageous, if the pipe to which the fusion tape 1 is welded is based on the same plastics material.

[0049] It has likewise proven advantageous for the width or diameter of the contact element 7, in cross-section, to be less than or equal to the thickness 8 of the heating element 3, which may be inferred from FIG. 6. The smaller or thinner is a region on the heating element 3, the higher is the power consumption there, and the more heat is generated. In order to ensure at this point, at the transition from the contact element 6 to the heating element 3, that the current flow 12 is provided or the heating element 3 is not overheated or melted through at the transition, as mentioned above the heating element 3 or the thickness 8 thereof is wider than or equal to the width of the contact element 6.

[0050] By varying the width of the heating element cross-section along the direction 12 of current flow, the heat generation in the corresponding regions is influenced and the temperature in the corresponding regions thereby adjusted or influenced. At points with a large or wide heating element cross-section, less power is consumed, whereby less heat is generated and the plastics material is melted to a correspondingly lesser extent or with a greater delay, while regions of the heating elements 3 with a smaller or thinner cross-section generate large amounts of thermal energy and the plastics material is melted strongly or quickly there.

[0051] In this way, for example, marginal regions 4 or other regions in which melting is undesirable or should proceed only to a slight degree or with a delay, may be correspondingly wide.

[0052] FIG. 8 shows a preferred application of an electrofusion tape 1 according to the invention as a component part of a fixed-point fastening 11. The embodiment illustrated shows a pipe clamp 10, which is placed around the electrofusion tape 1. Through the configuration of the jacket element 2 of the electrofusion tape 1, which is thicker in the marginal regions, displacement in the axial direction of the pipe is limited. Alternatively, a fixed-point fastening is also conceivable which is fastened between two electrofusion tapes 1 welded onto the pipe which serve as limit stops, as illustrated in FIG. 9.