EP1091623B1 - Heating conductor with raccording element and/or closing element and its manufacturing process - Google Patents

Abstract

Heat conductor comprises a connecting element (1A,1B) and a heating element (2) having a heating strip (3) and heating strip cords (4,5) and surrounded by a fluoropolymer protective layer (6). A further fluoropolymer plastic material is applied in the region of the connecting elements. An Independent claim is also included for a process for the production of a connecting element for a heat conductor comprising cutting a heating strip with heating strip cords in a prescribed region for the connecting elements and exposing the cords; applying a fluoropolymer plastic layer to the strip; applying a screen covering (8) to the plastic layer; back-cutting the covering layer in the region of the connecting elements; connecting one end of a extension line (9) to the connection point (8A,8B); applying an outer protective casing made of a fluoropolymer plastic to the heat conductor and the hot conductor connections; and finishing the connecting element regions by connecting lines to the cords and/or providing the lines with contact elements.

Description

The invention relates to a heating conductor with a connection element and / or a Termination element and a method for producing a connection element and / or a terminating element on a heating conductor.

Such heating conductors are used for heating piping systems, in particular water pipes, water tanks, valves and fittings and components in which liquid products are transported in order to achieve an active antifreeze. In particular, in an aircraft, which is exposed on long flights an extreme outside temperature, a freezing of the water pipes (sewage and fresh water) is possible without adequate frost protection. This could lead to the failure of the entire fresh water or sewage system and thus make it impossible, for example, a toilet use for the passengers.
The heating tapes used for the Heizleiteranordnungen have according to the prior art, a heating element with connecting wires (strands) on. The heating element is protected by an insulating layer of fluoropolymer plastic. A protective conductor braid is arranged on this inner jacket and a plastic outer protective jacket surrounds this heating conductor. The heating tapes are usually sold by the meter and must be assembled for the corresponding application. For the connection of several heating conductors or the connection of the heating element to a power supply, a connecting piece end to make the heating tape, wherein first on the outside and inside stripped heating band, the connecting wires are exposed and the heating element is shortened so that the connecting wires reach a sufficient length, the then used as a connection line. The protective conductor braid must be combed out and twisted and connected to an additional extension cable. The lengths of the connecting leads and the extension lead from the protective braid are adjusted so that they are flush. The transition region between the heating cable and leads must be pressure-tight sealed in a complex process and made resistant to chemical influences and heat exchange, as for an application in an aircraft, the factors influencing vibrations, heat exchange, low pressure conditions and chemical effects are essential. For this, according to the known state of the art, at least one respective adhesive / potting compound is applied manually and coated with a heat-shrinkable tube. A complex Klebevorehandlung is necessary, the following steps must be carried out in order to achieve a sufficient connection between epoxy and the FEP fluoropolymer plastic surface of the heating tape: Roughen the outer and inner shells; Clean adhesive area with cold cleaner, eg ethanol; Apply etchant, eg Tetra Etch, and allow to act; Rinse with deionized water and rinse with cold cleaner; Drying the heating tape in a convection oven. After this pretreatment, the application of the epoxy adhesive and the bonding of the heat-shrinkable tube must take place within a limited period of time. Since several shrink tubes are glued in several layers, the time required for the production of this connection area multiplies. In addition, under mechanical stress (during installation, vibrations) a detachment at the splice occur, since the epoxy adhesive is cured relatively rigid, but the fluoropolymer plastic (FEP) remains flexible.
Also, a special workplace with its own exhaust device is necessary for the etching process. The use of etchants causes health problems and disposal of the etchant is associated with additional costs.
Even at a final piece of a heat conductor, this complex pre-treatment with an etching process to prepare a bond with epoxy adhesive and FEP material is necessary.

From DE 34 28 460 is a connection arrangement of two doppeladriger electrical Cables known. It is a sprayed between the junctions of both conductors Fluoropolymer introduced to a shift of the conductor ends and thus the danger prevent a short circuit as well as a reliable isolation between the Both conductors by means of the injection plastic (the flowing fluoropolymer) to achieve. However, there is no fusion between the two by means of a sprayed connection Fluoropolymer layers achieved, which are sufficiently pressure and moisture-proof in the area of terminals or terminations of a heat conductor is to the conditions of a Application in the aircraft with vibrations, heat exchanges, low pressure conditions and the effects of chemicals.

In DE 197 26 418 and DE 197 26 419 Heizleiteranordnungen are shown, which can be coupled together by means of connection modules or to a corresponding Power supply can be connected. Here is provided as a connection technology, to provide the transition area with a split housing, wherein the interior of the housing after completion of the connections on all sides with an adhesive / potting compound is added to protect against moisture and to ensure liquid entry. To a liability of the potting compound to ensure with the FEP fluoropolymer surface is in this Solution also a Klebevorbehandlung, for example by means of etching, necessary. Here are also the disadvantages already mentioned, such as time-consuming Pretreatment, health risks when using caustics, like Tetra Etch as well as their necessary disposal.

The invention is therefore based on the object, a generic heating conductor to be provided with a connection element and / or a closure element, which eliminates the above-mentioned disadvantages and especially for the Use in the field of aircraft water systems is suitable and opposite the factors influencing vibration, heat exchange, low pressure conditions and Effects of chemicals achieved sufficient sealing effect and penetration of moisture or liquids in the terminal area of the heating element prevented. A method for producing such a heat conductor is specify.

This object is achieved in a generic heat conductor with the in claim 1 or 9 measures. Process for the preparation a connection or termination element on a heating conductor are in the claims 18 and 33 indicated.

It is particularly advantageous that health-damaging surface treatments the FEP layer and pollutants, such as caustics, be avoided. In addition to the fluoropolymer plastic material FEP, the best properties for skydrole resistance, moisture protection, have a Isolierschutz and good flexibility are no further Plastic materials necessary. Additional components, such as heat shrink tubing are no longer required and thus the time required to produce the Connection element or terminating element at the heating conductor considerably reduced.

Further developments and advantageous embodiments are in the dependent claims specified.

In the drawings, embodiments of the invention are shown below will be described in more detail with reference to FIGS 1 to 4. In the figures the same components are provided with the same reference numerals.

Fig. 1

den Aufbau eines Heizleiters mit einem endseitig angeordneten Anschlußelement sowie die Verfahrensschritte a) bis f) zur Herstellung eines Anschlußelementes am Heizleiter,

Fig. 2

den Aufbau eines Heizleiters mit einem endseitig angeordneten Abschlußelement sowie die Verfahrensschritte g) bis i) zur Herstellung eines Abschlußelementes am Heizleiter,

Fig. 3

den Heizleiter mit einer zweiten Ausführungsform eines Anschlußelementes sowie die Arbeitsgänge aa) bis ii) zur Herstellung des Anschlußelementes und

Fig. 4

die Arbeitsschritte kk) bis nn) zur Fertigstellung der zweiten Ausführungsform eines Abschlußelementes eines Heizleiters.

It shows

Fig. 1

the construction of a heat conductor with a terminal arranged terminal element and the process steps a) to f) for producing a connection element on the heating element,

Fig. 2

the construction of a heat conductor with an end element arranged end element and the process steps g) to i) for producing a closure element on the heating element,

Fig. 3

the heating conductor with a second embodiment of a connecting element and the operations aa) to ii) for the preparation of the connecting element and

Fig. 4

the steps kk) to nn) for completing the second embodiment of a closure element of a heat conductor.

In Fig. 1, Figure a) is the basic element of a heat conductor 1, a heating element. 2 seen. The heating element 2 is made in the embodiment shown a plastic, especially fluoropolymer plastic (FEP) / carbon composite tape 3, a so-called heating tape which von Heizbandlitzen 4 and 5, preferably formed as copper or nickel strand, is crossed. in the Area of a Heizleiteranschlusses 1A and 1B are the Heizbandlitzen 4 and 5 exposed and are used as connecting wires for connection to the supply voltage used the circuit. The heating element 1 are already at their Production made in the required lengths. The length of the heating conductor arises according to the requirements of the to be laid and heated Water pipes. In a solution according to the invention that, usually in Meterware existing heating element 2 in the connection area not separated, but it is only the strand 4 and 5 exposed and a separation of the Heat conductor 1 takes place only in a later manufacturing step. This is the production not only the Heizleiteranschlusses 1A, but at the same time the Production of another Heizleiteranschlusses 1B possible.

In Fig. 1, Figure b) it can be seen that after exposing the Heizbandlitzen 4 and 5, an extrusion is carried out and a layer 6 of fluoropolymer plastic (FEP - fluorine-ethylene-propylene) on the heating element 2 (consisting of heating tape and connecting wires 4 and 5) is applied. With the extrusion of this plastic molding compound, an insulating and protective layer 6 is produced, which is water and pressure tight, in particular in the transition region 7 of the layer 6 from the heating tape 3 to the exposed Heizbandlitzen 4 and 5 and thus improved sealing behavior at the Heizleiteranschlüssen 1A and 1B is guaranteed.
All extrusions are done under vacuum to avoid air bubbles.

Fig. 1, Figure c) shows a further process step for the production of the heat conductor 1 with a Heizleiteranschluß 1A (or 1B). After the insulating layer 6, a braided screen 8 is applied to the heating element 2. The shield braid 8 is preferably made of a spindled copper / nickel braid.
This screen braid 8 must be cut back in the region of the heating conductor connections 1A and 1B, as shown in Fig. 1, Figure d) can be seen. An additional extension line 9 provided with an FEP jacket is connected to the braid 8.
This can be done in a conventional manner by combing out and twisting the braid and connecting to the extension line or - as shown in Fig. 1, Figure d) - there is a welding or splicing of the lead terminal 9A and 9B with the corresponding side of the shield braid 8A and 8B. Before welding or splicing, the extension line 9 is selectively fixed in the manner shown with adhesive. Furthermore, the connecting wires 4 and 5 and the extension line 9 are fixed by means of a Teflon tape 10A and 10B.

In Fig. 1, Figure e) is the finished after the process steps a) to d) Heating conductor 1 can be seen, which finally provided with a protective jacket 11 becomes. This protective jacket 11 is also made of fluoropolymer plastic (FEP) and is in an extrusion on the heat conductor 1 and the Heizleiteranschlüsse Applied 1 A and 1 B, wherein the connecting wires 4, 5 and the Extension line 9 are completely enveloped. After extruding it will in the area of the connecting wires 4 and 5 and the extension line 9 the Heating element 2 separated. The Heizleiteranschluß 1A and 1B can now to get finished.

Fig. 1, Figure f) shows the finished heating conductor 1 with the heating conductor connection 1A. The ends of the lines 4, 5 and 9 are freed from the complete FEP sheath 11 and 6 and only each separate line remains provided with an FEP protective layer. By punching out the three lines 4, 5 and 9 production technology with quite simple means a separation of the lines is possible. Each line 4, 5 and 9 is provided at its end with Einzelsteckkontakten 12, 13 or 14. Preferably, these contacts are squeezed. The free cable ends 4, 5 and 9 are provided for identification with colored (red, white or blue) shrink tubing 15, 16, 17. The exit region 18 of the connecting wires 4 and 5 and the extension line 9 from the FEP protective jacket 11 is extruded again or heat-welded. It creates the area 11A. For a sufficient tightness against the braided shield 8 is made.
On the protective jacket 11 and the area 11 A markings can be applied to facilitate the identification in a further use of the heating element 1.

In Fig. 2 is an embodiment in various states of completion from the heating conductor 1 with closure elements 1C and 1D shown. For the Production of a terminating element 1C on the heating conductor 1 are the same Steps as for the preparation of connecting element 1A or 1B according to FIG. 1, picture a) to c). So in the first step for the Heating conductor 1 on the heating element 2 with the heating tape 3 in the end of the Heat conductor 1, the Heizbandlitzen 4 and 5 expose (Fig. 1, Figure a)), continue is a layer 6 of fluoropolymer plastic (FEP) by means of extrusion applied (image b)) and a braid 8 is via the FEP layer. 6 pulled (picture c)).

Based on Fig. 2, Figure g), the next step can be described. The shield braid 8 is also cut back here, but over the Area of the exposed Heizbandlitzen 4 and 5 also, so that a part from the heating tape 3 is no longer covered by the shield braid 8. Are visible the areas 8C and 8D of the braided shield 8, which is the cut back Braided shield 8 in the region of the closure element 1C and 1D represents.

In Fig. 2, Figure h) is shown that a narrow Teflon tape 19 A and 19 B, the fixed back shielded braid 8C or 8D. A connection of the Braided screen 8C or 8D with an extension line is on the terminating element 1C and 1D not necessary, so that the wire ends of Braided shield 8 can be completely sheathed. The connecting wires (Heizbandlitzen) 4 and 5 are also shortened, so that an end of the End elements 1C and 1D completely free of strands and thus of current-conducting Components is.

In Fig. 2, Figure i) it can be seen that an outer protective jacket 20 by a final extrusion process over the braid 8 and the areas the termination elements 1C and 1D is applied. After extruding can the heating element 2 is cut between the closure elements 1C and 1D become. The separation points 20A and 20B become the final seal filled with FEP plastic material and welded. Through the heat supply For example, the outer protective jacket 20 and the FEP layer 6 become one with each other connected, that a final tightness is achieved and a bond with an additional heat shrink tube is no longer necessary.

In FIG. 3, the heating conductor 1 with a second embodiment of one end arranged connection element 1F, showing the manufacturing steps aa) to ii). Fig. 3, picture aa) shows the basic element of a Heat conductor 1, a heating element 2, as it is already in the description of Figure 1, Figure a) was explained in detail. In this embodiment of the heat conductor. 1 However, with the connection element 1F is not provided, two Heizleiteranschlüsse to manufacture at the same time, as it is in the Heizleiteranschlüssen 1A and 1B of the first embodiment is the case.

In Fig. 3, Figure bb) it can be seen that an extrusion is carried out and a layer 6 of fluoropolymer plastic (FEP - fluoroethylene-propylene) on the heating element 2 (consisting of heating tape or heating matrix 3 and Heizbandlitzen 4 and 5) is applied. By extruding this plastic molding compound an insulating and protective layer 6 is generated, which due to the used material is water and pressure tight and skydrolfest.

Fig. 3, Figure cc) shows a further process step for the preparation of the heat conductor 1 with the Heizleiteranschluß 1F. The heating element 2, consisting of the heating tape 3 and Heizbandlitzen 4 and 5, is cut in the appropriate length and in the connection area the Heizbandlitzen 4 and 5 are exposed to be used as connecting wires can. On the insulating layer 6, a braid 8 is applied. The shield braid 8 is preferably made of a spindled copper / nickel braid.
This screen braid 8 must be cut back in the region of the heating conductor connection 1F. In order to be able to carry out the subsequent operation (image dd) provided as an additional safety measure, corona treatment of the heating tape or heating matrix end face 3A and of the extruding layer 6 is provided in this area. With the corona treatment, a surface treatment or a roughening of the layer is achieved by means of electron bombardment in order to achieve sufficient adhesion for the next step, the application of an epoxy layer 21 or a butyl plastic filling compound.

In Fig. 3, Figure dd), this epoxy layer 21 can be seen, which was applied in the region of Heizmatrixstirnseite 3A. This epoxy layer 21 is applied, for example, by dipping the heating conductor 1 with the appropriate line end in an epoxy solution / epoxy adhesive and then allowed to dry. As another way to achieve a moisture seal, a butyl plastic fill may be applied to the lead end and splice area.
The epoxy layer 21 or the butyl layer is an additional security that no moisture can penetrate into the end face of the heating element 1 (arc tracking) and the functionality of the heating element 1 is not impaired.

In a next operation, which is shown in Fig. 3, Image ee), the Braided screen 8 fixed by means of a Teflon tape 22. The heating conductor connecting wires FIGS. 4 and 5 are provided with kapton insulated leads 24 and 25 which are FEP jacketed and preferably colored (red, blue) are executed by means of passage connector 23 connected. About these splice connections become to Insulated and protective shrink sleeves arranged. An adhesive / potting compound, as is necessary in the prior art is before the Mounting the heat shrink tubing is no longer necessary.

Fig. 3, Figure ff) shows the state of the heating element 1, in which an additional, provided with an FEP sheath extension line / Kapton line 26 is connected to the braid 8.
This can be done by conventional combing and twisting of the braid and connection to the extension line 26 by means of passage connector 23 and subsequent coating with a shrink tube. The twisted end of the shield braid 8 is designated by the reference numeral 8E.

The next operation, in Figure 3, Figure gg), shows the use of an FEP molding 27, which is pulled over the terminal portion of the heat conductor 2 and the three through connectors 23 together with lines 24, 25 and 26 to center and a reproducible series connection to reach. The molded part 27 is preferably formed as a hood, which can be pulled over the terminal region of the connecting wires 4 and 5 and the shield braid 8 with the connected lines 24, 25 and 26. The heating tape 3 facing the end 27A of the molding 27 has such an inner diameter that it can be pushed over the epoxy layer 21 and rests on the Teflon tape 22. The outer diameter of the molding 27 is adapted at the end 27A to the outer diameter of the teflon wrap 22 to achieve a smooth transition. The molded part 27 is preferably cylindrical in this area and tapers towards the other end 27B. The inner contour of the molded part 27 also tapers toward the other end 27B and is formed so as to cover the terminals of the connecting wires 4, 5 and the shielding braid 8 to the lines 24, 25 and 26 and the ends 27B of the molded part 27A 24, 25, 26 defined at the exit of the lines 24, 25, 26 defined or guided. For this purpose, the end 27B is filled with FEP material so that they form receptacles for the lines 24, 25 and 26. Due to the FEP sheath of the leads 24, 25 and 26, the FEP material molding end 27B may be fused to the lead sheaths. The fusion region 28 is shown in FIG. The merging will be done in the next step.
If, instead of the use of the epoxy layer 21 butyl-plastic filling compound is used, this butyl mass is introduced only after pushing the FEP molding 27 into the cavity between the molding 27 and the wrapped by the molding 27 parts and only then is the extrusion.

In Fig. 3, Figure hh) is the production of a second extrusion layer 29 of FEP material on the heating tape 3 and the zylinderfömigen part of the molding 27th seen. At the transition region 30 between the extrusion 29 and the FEP molding 27 and in the fusion region 28 between molding end 27B and lead sheaths of the lines 24, 25 and 26 is the respective FEP material fused together. Finally, to the cable ends the lines 24, 25 and 26 plug contacts 31, 32 and 33 squeezed and the water and pressure-tight connection element 1F at the heating conductor. 1 is essentially completed.

Finally, as shown in Fig. 3, Figure ii), the heating element 1 is to be marked. A license plate 34 can be printed on the heating element 1. When Details are provided part numbers. The plug contacts 31, 32, 33 are covered with heat-shrinkable tubes, also with designations such as Part markings are provided.

4, the heating conductor 1 with a second embodiment of an end arranged closure element 1G, showing the manufacturing steps kk) to nn). For the production of a closure element 1G at the heating element 1 are initially the same steps as for the production from the connection element 1F according to FIG. 3, FIGS. aa) to cc). So are in the first step for the heating element 1 on the heating element 2 with the heating tape. 3 in the end region of the heat conductor 1, the Heizbandlitzen 4 and 5 expose (Fig. 3, picture aa)), furthermore a layer 6 made of fluoropolymer plastic (FEP) applied by extrusion (Figure bb)) and a braided screen 8 is on the FEP layer 6 pulled (Figure cc)). For more details go to the corresponding Figure description referenced.

In the picture kk) the prepared so Heizleiterende is shown. To the as additional Subsequent operation (Figure ll)) to be able to perform is a corona treatment of Heizband- or Heizmatrixstirnseite 3A and the extrusion layer 6 are provided in this area. With The corona treatment is a surface treatment or roughening of the Achieved layer by electron bombardment, for the next step, the Applying an epoxy layer 35 or a butyl-plastic compound, sufficient To gain liability.

In Fig. 4, Figure ll), this epoxy layer 35 can be seen in the field of Heizmatrixstirnseite 3A was applied. This epoxy layer 35 becomes For example, applied by heating conductor 1 with the corresponding End of line in an epoxy solution / epoxy dips and then allowed to dry. Instead of the epoxy layer 35 is also the application of a Butyl plastic compound possible. The epoxy layer 35 or the butyl layer is An additional security that no moisture in the face of the heating element 1 can penetrate (arc tracking) and thus the functionality of the Heizteiters 1 is impaired.

Fig. 4, Image mm) shows as a further process step, the application of a Fixation of the shield braid 8 by means of a Teflon tape 36. With this Teflon fixation 36, the braid 8 on the first extrusion 6 attached. The Heizbandlitzen 4 and 5 are each by means of a Teflon tube 37 or 38 isolated. An end cap 39 made of FEP material will be slid onto the prepared Heizleiterende, the open end 39A is preferably pushed so far that it on the Teflon fixation 36th is applied. The closed end 39B of the end cap is preferably rounded. With the use of such a FEP molding as the end cap 39 is a reproducible series completion achieved. When butyl plastic fill against is used in the hollow areas of the moisture End cap 39 introduced.

The last step in the production of the terminating element 1G am Heating conductor 1 is explained with reference to FIG. 4, Figure nn). At least the Whole end portion of the heat conductor 1 is a second extrusion 40th generated. The FEP layer 40 is in a melting region 41, the at least the cylindrical end portion of the end cap 39 (before the beginning of the rounding) comprises heat-welded to the extruding layer 40.

LIST OF REFERENCE NUMBERS

1

- heating conductor

1A, B

- Connection element (1st version)

1C, D

- Terminating element (1st embodiment)

1F

- Connecting element (2nd version)

1G

- Terminating element (2nd embodiment)

2

- heating element

3

- Heating cable / Heizmatrix

4.5

- Heizbandlitzen / connecting wires

6

- FEP layer

7

- Transition area

8th

- braided shield

8A, 8B, 8C, 8D, 8E

- Twisted end of the screen braid

9

- extension cable

9A, 9B

- cable connections

10A, 10B

- Teflon tape

11

- Protective jacket made of FEP

11A

- heat sealed area of 11

12, 13, 14

- Single plug contacts

15, 16, 17

- Colored heat shrink tubing

18

- Exit area from 11

19A, 19B

- Teflon tape

20

- Protective Jacket

20A, 20B

- separation points

21

- Epoxy layer or Butylkunststoffüllmasse

22

- Teflon tape

23

- Channel connector

24,25,26

- Kaptonleitungen

27

- FEP molding

27A, 27B

- first and second ends of the molded part

28

- fusing range

29

- second extrusion layer

30

- Transition area

31, 32, 33

- plug contacts

34

- Mark

35

- Epoxy layer

36

- Teflon tape

37, 38

- Teflon tubing

39

- endcap

39A, 39B

- first and second end of the cap 39

40

- second extrusion layer

41

- melting range

Claims (37)

1. A heating conductor (1) having a terminal element (1A, 1B; 1F), the heating conductor (1) consisting substantially of at least one heating element (2), which comprises a heating tape (3) and heating tape wires (4, 5) and is sheathed in a fluoropolymer protective layer (6), further fluoropolymer plastics material (11; 27, 29) being applied in the region of the terminal elements (1A, 1B; 1F) for sealing purposes, characterised in that the further fluoropolymer plastics material forms a second fluoropolymer layer (extrusion layer 11; 29), which is either fused at least in the region of the terminal element (1A, 1B) with the first fluoropolymer protective layer (6) to achieve a pressure- and moisture-tight seal (11A) or a plastics moulding (27) is provided in the region of the terminal element (1F), which moulding is fused in a transitional zone (30) with the second fluoropolymer layer (29).
2. A heating conductor according to claim 1,
   characterised in that a shielding braid (8) is applied to the fluoropolymer protective layer (6), which braid is removable in the region of the terminal elements (1A, 1B; 1F).
3. A heating conductor according to claim 1,
   characterised in that the fluoropolymer layers (6, 11; 29) and the plastics moulding (27) consist of FEP material.
4. A heating conductor according to claim 1 or claim 3,
   characterised in that the plastics moulding (27) is of cap-like construction, wherein one end (27A) is arranged on the heating tape (3), the middle region of the moulding (27) covers the transition between the heating tape wires (4, 5) and the connected lines (24, 25, 26) and the other end (27B) is provided in the region of the emerging lines (24, 25, 26).
5. A heating conductor according to any one of claims 1 to 4,
   characterised in that a plastics layer (21) is provided at one end face (3A) of the heating tape in the region of the emerging heating tape wires (4, 5) to achieve a pressure- and moisture-tight connection.
6. A heating conductor according to claim 5,
   characterised in that the plastics layer (21) is formed of epoxy or butyl polymer filler.
7. A heating conductor (1) having a terminating element (1C, 1D; 1G), the heating conductor (1) consisting substantially of at least one heating element (2), which comprises a heating tape (3) and heating tape wires (4, 5) and is sheathed in a fluoropolymer protective layer (6), further fluoropolymer plastics material (20; 39, 40) being applied in the region of the terminating elements (1C, 1D; 1G) for sealing purposes, characterised in that the further fluoropolymer plastics material forms a second fluoropolymer layer (extrusion layer 20; 40), which is either fused at least in the region of the terminating element (1C, 1D) with the first fluoropolymer protective layer (6) to achieve a pressure- and moisture-tight seal (11A) or a plastics end cap (39) is provided in the region of the terminating element (1G), which end cap is fused in a fusion zone (41) with the second fluoropolymer layer (extrusion layer 40).
8. A heating conductor according to claim 7,
   characterised in that a shielding braid (8) is applied to the fluoropolymer protective layer (6), which braid is removable in the region of the terminating elements (1C, 1D; 1G).
9. A heating conductor according to claim 7,
   characterised in that
   the fluoropolymer layers (6, 20; 40) and the plastics end cap (39) consist of FEP material.
10. A heating conductor according to any one of claims 7 to 9,
    characterised in that the plastics end cap (39) is arranged with one end (39A) on the heating tape (3) and the closed end insulates the exposed heating tape wires (4, 5).
11. A heating conductor according to any one of claims 7 to 10,
    characterised in that a plastics layer (35) is provided at one heating tape end face (3A) in the region of the emerging heating tape wires (4, 5).
12. A heating conductor according to claim 11,
    characterised in that the plastics layer (35) is formed of epoxy or butyl polymer filler.
13. A heating conductor according to any one of the preceding claims,
    characterised in that the pressure- and moisture-tight connection may be produced by means of a thermal welding device or an extrusion device.
14. A method of producing a terminal element (1A, 1B; 1F) on a heating conductor (1), wherein the following method steps are performed:

    a) a heating tape (3) with at least one heating tape wire (4, 5) is cut open in a region provided for terminal elements (1A, 1B; 1F) on the basis of given length measurements and the at least one heating tape wire (4, 5) is exposed,

    b) a fluoropolymer plastics layer (6), preferably consisting of FEP (Fluoro Ethylene Propylene), is applied to the heating tape (3) by an extrusion process,

    c) a shielding braid (8) is applied to the fluoropolymer plastics layer (6),

    d) the shielding braid (8) is cut back in the region of the at least one terminal element (1A, 1B; 1F), wherein a connecting terminal (8A, 8B; 8E) is formed at each cut point of the shielding braid (8),

    e) an end of an extension line (9; 26) is connected to the connecting terminal (8A, 8B; 8E),

    f) an outer protective sheath (11; 29) of fluoropolymer plastics, preferably FEP, is applied to the heating conductor (1) and at least to some regions of the heating conductor terminals (1A, 1B; 1F) by at least one further extrusion process,

    g) the terminal element zones (1A, 1B; 1F) are finished by connecting lines (24, 25) to the heating tape wires (4, 5) and/or by providing the lines (4, 5, 9; 24, 25, 26) with contact elements (12, 13, 14; 31, 32, 33).
15. A method according to claim 14,
    characterised in that the connecting terminal (8A, 8B; 8E) is formed on the shielding braid (8) by welding or splicing with the extension line (9; 26).
16. A method according to claim 14,
    characterised in that the connecting terminal (8A, 8B; 8E) is formed on the shielding braid (8) by combing out and twisting of the braid.
17. A method according to any one of claims 14 to 16,
    characterised in that the heating tape wires (4, 5) and the extension line (9) are fixed by means of a Teflon tape (10A, 10B) prior to connection of the extension line (9) to the shielding braid (8).
18. A method according to any one of claims 14 to 17,
    characterised in that the heating tape (3) with the heating tape wires (4, 5) and the extension line (9) are cut through after extrusion of the outer protective sheath (11) (step f) to form the heating conductor (1) with the terminal element (1A) and a further heating conductor (1') with the terminal element (1B).
19. A method according to any one of claims 14 to 18,
    characterised in that the outlet zone (11A) of the lines (4, 5 and 9) from the protective sheath (11) is thermally welded or extruded to achieve sufficient tightness.
20. A method according to any one of claims 14 to 19,
    characterised in that the lines (4, 5, 9) are separated in the terminal zone (1A) and in each case provided with a contact element (12, 13, 14).
21. A method according to claim 20,
    characterised in that the contact elements (12, 13, 14) take the form of plug-in contacts, which are crimped onto the ends of the lines (4, 5 and 9).
22. A method according to any one of claims 14 to 21,
    characterised in that the ends of the lines (4, 5 and 9) are provided with preferably coloured heat-shrinkable sleeves (15, 16, 17) for identification purposes.
23. A method according to any one of claims 14 to 16,
    characterised in that an FEP moulding (27) is arranged in the region of the terminal element (1F) after step e), which moulding (27) is drawn in the manner of a cap over the heating tape wires (4, 5) and the lines (24, 25) connected thereto as well as over the extension line (26) of the shielding braid (8).
24. A method according to claim 23,
    characterised in that one end (27A) of the FEP moulding (27) is applied to the shielding braid (8) and this region is sealed in watertight manner, in the middle region the heating tape wires (4, 5) and the lines (24, 25) connected thereto and the extension line (26) are covered and held and at the other end (27B) the lines (24, 25, 26) emerging from the end region are guided in defined manner.
25. A method according to either one of claims 23 or 24,
    characterised in that the Teflon-coated line sheaths are fused together with the FEP moulding (27) in a fusion zone (28) on the moulding end (27B) of the lines (24, 25, 26) emerging from the FEP moulding (27).
26. A method according to any one of claims 23 to 25,
    characterised in that a plastics, preferably epoxy, layer (21) is applied in the region of the heating tape end face (3A) of the terminal element (1F) prior to arrangement of the FEP moulding (27) in the region of the terminal element (1F).
27. A method according to any one of claims 23 to 25,
    characterised in that a butyl polymer filler material is introduced into the cavities between the FEP moulding (27) and the internal parts.
28. A method according to claim 26 or claim 27,
    characterised in that, prior to application of the plastics layer (21) or of the butyl material, the relevant surface of heating tape (3) and heating tape surface (3A) is pretreated by corona treatment.
29. A method of producing a terminating element (1C, 1D; 1G) on a heating conductor (1), wherein the following method steps are performed:

    a) a heating tape (3) with at least one heating line (4, 5) is cut open in a region provided for terminating elements (1C, 1D; 1G) on the basis of given length measurements and the at least one heating line (4, 5) is exposed,

    b) a fluoropolymer plastics layer (6), preferably consisting of FEP, is applied to the heating tape (3) by an extrusion process,

    c) a shielding braid (8) is applied to the fluoropolymer plastics layer (6) and cut back in the region of the terminating elements (1C, 1D; 1G),

    d) the wires (4, 5) of the heating lines are rendered conduction-less in the end region of the terminating elements (1C, 1D; 1G),

    e) an outer protective sheath (20; 40) of fluoropolymer plastics, preferably FEP, is applied to the heating conductor (1) and at least in part to the heating conductor terminating zones (1C, 1D; 1G) by a further extrusion process,

    f) in the end region (separation points 20A, 20B); fusion zone 41) of the terminating elements (1C, 1D; 1G), the FEP material is thermally welded or extruded for final sealing to achieve sufficient tightness.
30. A method according to claim 29,
    characterised in that, after step e), the terminating element zones (1C, 1D) are cut through to form the heating conductor (1) with the terminating element (1C) and a further heating conductor (1') with the terminating element (1D), so forming separation points (20A, 20B).
31. A method according to claim 30,
    characterised in that the separation points (20A, 20B) are filled with fluoropolymer plastics, preferably FEP, prior to final sealing.
32. A method according to claim 29,
    characterised in that, after step d), an end cap (39) of fluoropolymer plastics, preferably FEP, is arranged on the heating conductor terminating zone (1G).
33. A method according to claim 32,
    characterised in that, before the end cap (39) is pushed on, a plastics (epoxy) layer (35) is applied in the region of the heating tape end face (3A) of the heating conductor terminating zone (1G).
34. A method according to claim 32,
    characterised in that a butyl polymer filler is introduced inside the end cap (39) for sealing purposes.
35. A method according to claim 33 or claim 34,
    characterised in that, prior to application of the epoxy layer (39) or butyl polymer filler, the relevant surface of heating tape (3) and heating tape surface (3A) is pretreated by corona treatment.
36. A method according to any one of claims 29 to 35,
    characterised in that a Teflon tape (19A, 19B) is attached to each of the cut points of the shielding braid (8C, 8D) to fix the cut points.
37. A method according to any one of the preceding claims,
    characterised in that the extrusion and thermal welding processes proceed under a vacuum.

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