DE1479231A1 - Method for connecting plastic pipes - Google Patents

Description

Method of connecting plastic pipes The invention relates to relate to a number of methods of joining plastic pipes, for example Plastic covers of plastic-sheathed cables and other plastic pipes with the help of electric heating wires, in particular to a new process to simplify Way to get a reliable connection of plastic-sheathed cables.

According to the trend, more and more plastic materials, such as polyethylene and polyvinyl chloride for cable jackets and other pipes the task of connecting these plastic masses is also becoming increasingly important. Especially in the Area of communication cables, where for example Alpeth and Stalpeth cables the the usual lead sheathing is being replaced more and more, is the connection from Plastic-sheathed cables are a very important task that must be paid for.

There are already various options for connecting plastic-sheathed cables Procedure known; for example, additional lead sleeves, which according to the usual Method of soldering is mechanical junction boxes that have a rubber seal use ; the gluing process using self-adhesive tape or adhesive will ; the epoxy putty process, in which epoxy putty at the connection point, the Contains fillers and hardeners.

All of these methods have certain drawbacks in terms of simplicity, adequate and reliable airtight seal and cost. That's why a new method for connecting plastic-sheathed cables was desired, that solves all of these problems.

The inventors propose a method of joining plastic-sheathed Cables with the help of electric heating wires to accomplish the above task. The method according to the invention provides measures to be carried out on the surface of the plastic-sheathed cable to attach turns of the electrical heating wires, whereby the electrical heating wires made of plastic-coated or uninsulated bare Wire can be made around an overlapping plastic socket over the heating wires to attach to a current from a source, for example a portable battery, to supply and to make the connection between plastic sheathing and Manufacture plastic bushing by welding together with electrical wires.

So far it has been a corresponding process for connecting plastic-sheathed cables with the help of electrical heating wires necessary that Winding heating wires very tightly, with little space between them, in order to achieve a to achieve a high degree of efficiency. This tight winding of the electrical heating wires the likelihood of a short circuit between adjacent turns increased of the electric heating wires.

Experiments have found that when using bare wires these adjacent turns could produce a direct short circuit and that Even the use of plastic-coated wires occasionally ends with a course could occur between adjacent wires when the plastic insulation material was heated and softened by the heating current in the wires.

Cause such short circuits between adjacent connections often uneven and unsatisfactory welding and even with a completed connection one has an increased loss of performance and a significant decrease in Working capacity of the batteries.

The other hand could be the likelihood of a short circuit by large winding spacing of the heating wires can be reduced, if in this case still a satisfactory heating efficiency and a satisfactory connection was achieved. Furthermore, when using very thin heating wires, one usually required a considerable time to attach the thin heating wires to the cable, and it was particularly difficult, this winding in narrow and dark manholes or at Make overhead cable connections.

It was desirable to use this method of joining plastic encased Cables with a suitable plastic socket overlapping on the plastic sheaths is attached and where the plastic bushing and the plastic sheaths through Heat can be linked together to improve. Furthermore, it was the task a method of connecting cables by simply fitting plastic sheathing and socket or by joining two plastic tubes of the same directly together Diameter without using a socket.

By the way, the protection against the effects of moisture in the area of the Connection was largely achieved through the plastic bushing mentioned above. this even with Stalpeth communication cables, those with a waterproof metal jacket be provided. However, the plastic bushing is not completely waterproof, and they are has the disadvantage of allowing a small amount of moisture to penetrate. Although the The amount of water ingress is extremely small is can over the years a considerable amount of moisture 4-a-can get into the cable through the plastic socket.

The main object of the invention is to overcome the disadvantages described above to avoid having to help with the usual methods of connecting cables electric heating wires occur.

The invention relates to a new and economical method for Connection of plastic pipes, especially plastic-sheathed cables, and simple Means to obtain a particularly airtight and mechanically strong connection.

The main object of the invention is the heating wires that be used to connect the plastic pipes, so as to improve the fact that there is a short circuit can be completely avoided even if the heating wires are tightly wound, thereby avoiding high losses of battery energy and providing an effective connection the plastic cable is reached.

The second object of the invention is to wind the thin heating wires, Avoid turn by turn, as is necessary with the usual methods. This is achieved through the use of ribbon-shaped heating wires, which consist of several individual ones Wires exist, or through the use of connecting plastic sockets, into which the heating wires are embedded and which improves the quality of the connection, achieved.

The third object of the invention is to provide a new method of connection of plastic pipes with the help of electric heating wires, which makes it possible to the plastic tubes butt against each other instead of overlapping, as is the case with the usual methods connect to.

The fourth object of the invention is to provide a moisture-proof structure the connection of plastic pipes, which are connected with the help of electric heating wires to prevent water from entering the cable, especially the Ingress of water into the interior of plastic-sheathed communications cables; d - need a high degree of resistance gel moisture, perfect prevented, thereby improving the joining of plastic-encased Cables can be reached.

In order to achieve the objects described above, the invention comprises the following essential characteristics: Firstly, a method for connecting plastic pipes, in which the overlapping ends of the plastic tubes with the insertion of electrical Heating wires are connected to each other and by the current flow through the heating wires welded and so the overlapping ends are united with one another, the electrical heating wires a) from one wire with two insulating Layers of which the inner layer on the bare wire is a larger size Has thermal resistance as the su connecting plastic masses and the external one Isolieraohioht essentially consists of the same plastic material as the one below connecting plastic masses or b) are shaped like a band and made up of several wires exist, each of which has an inner insulating not with greater thermal resistance has ale the su connect plastic masses, with the single wires in parallel are arranged to each other and have an outer Bore insulating layer that the wires united with each other and which consists essentially of the same plastic mass like the following plastic masses.

Second, a method of connecting plastic pipes, the Push the ends of the plastic tubes together and in the area of the joint the plastic tubes around these electrical heating wires or ribbon-shaped electrical heating wires be wound, in which a plastic bushing made of almost the same plastic material, how the plastic mass to be connected is provided and where the two su zu connecting ends and the plastic socket by the electric current flowing through the heating wires flow, weld and thus be united with one another.

Third, a method of connecting plastic pipes in which in the plastic socket to be used has electrical heating wires embedded.

Fourth, a method of connecting plastic-sheathed communication cables, in which plastic bushings and the heating wires described are used and in which an additional, waterproof socket is provided in the plastic socket or at an additional plastic tube with a thin layer of waterproof metal coating is pushed over the separated area of the cable core, whereupon the plastic socket is pushed over the point to be connected.

For a better understanding of the invention, it is illustrated with the aid of the figures explained.

Fig. 1 shows a section through a connection of plastic-coated Cables, an electric heating wire being provided according to the method according to the invention is.

Fig. 2 shows, in section, an electric heating wire with double Insulating layer as used in the method according to the invention.

Fig. 3 shows in section an example of a band-shaped heating wire with two insulating layers according to the invention.

Fig. 4 shows the side view of the ribbon-shaped heating wire according to Fig. 3.

Fig. 5 shows a second exemplary embodiment for the inventive Procedure with heating wires make a longitudinal section through the connection of plastic tubes.

Fig. 6 shows a third embodiment for the invention Procedure.

Fig. 7 shows as a longitudinal section a fourth embodiment for the inventive method, wherein a plastic pipe with a thin metal layer is inserted on the surface of the plastic pipes and the connection as shown in Fig. 5 takes place.

Fig. 8 shows the longitudinal section through the connection of plastic tubes, as obtained in the method according to the invention according to FIG. 6.

Fig. 9 shows the longitudinal section through the connection of plastic pipes, as can be seen when applying the methods and means illustrated in FIGS. 1 to 5 receives.

10 and 11 show longitudinal sections through two plastic bushings according to the invention, in which the heating wires are embedded.

Fig. 12 shows a longitudinal section through a connection of plastic tubes with a socket as shown in FIG.

Fig. 13 shows a longitudinal section through the connection of plastic-coated Cables with a socket as shown in FIG.

14 shows the longitudinal section through a connection of Stalpeth communication cables, in which a first embodiment of the method for connecting plastic coated Communication cables with a waterproof plastic socket is shown.

15 and 16 show sections through the waterproof plastic bushing, as used in the embodiment of FIG.

17 and 18 show schematic diagrams for two possibilities, one watertight Manufacture plastic socket.

19 and 20 show further examples of waterproof plastic bushings.

21 shows a longitudinal section through the connection area of a plastic-sheathed cable with a waterproof sheathing over the severed Area of the cable core is attached and then attached to a plastic socket was to make the connection according to the method according to the invention with the help of electrical Manufacture heating wires.

22 and 23 show two plastic bushings in perspective with a thin metal layer, as used for a connection according to FIG can be.

Fig. 24 shows the principle how a plastic bushing according to Fig. 22 over attached to the separated area of the cable core of the plastic-sheathed cable can be.

FIG. 25 shows in section how a plastic tube according to FIG. 24 with the plastic sheath of the cables to be connected is connected.

Fig. 26 shows a plastic plate from which a plastic bushing is rolled according to FIG. 22 arises.

Fig. 27 shows a section through a test piece of a connection of Stalpeth cables.

Fig. 1 shows a first embodiment of the method according to the invention. The electric heating wire 3 is around one end of the plastic sheath 2 of the plastic-sheathed cable 1 is wound. This heating wire consists of either Wire with double insulation or from a ribbon-shaped heating wire that runs through Combination of a plurality of heating wires is created. A plastic sleeve 4 of the a plastic tube is pushed over the heating wire, and a fastening strap 5 is wrapped around this overlapping sleeve to press it on. Will the heating wire 3 from an electrical current from a voltage source, for example from a portable battery while the overlapping part of the sleeve is pressed is, the plastic shell 2 and the plastic sleeve 4 by the heat inextricably linked, and the connection is complete.

For the above connection method according to the invention is either an electric heating wire with double insulation or a band-shaped one electric heating wire made up of a plurality of heating wires is absolutely necessary Heating wire is described in more detail below.

Fig. 2 shows an example of a heating wire with double insulation. A first insulating layer 7 having a higher heat resistance than that to be connected plastic mass is applied to the heating conductor 6 in order to isoliera th electrical heating wire /. This insulated heating wire a is with a further insulation 8 made of almost the same plastic material as the one to be connected Plaat measures provided. The conductor 6 consists of one of the metals copper, aluminum, Iron, chromium-nickel, etc. The first insulating layer with a thermal resistance Larger than the plastic masses to be joined can be obtained by heat hardening of Enamel paints such as olein resin paint, formaldehyde paint on the conductor. If an even bigger one If heat resistance is required, you can use enamel paints such as polyester, polyamide etc. use.

In most cases, the enameled wires are sufficient for the windings of electrical machines are suitable for the requirements. These lacquer coatings are all made of thermosetting varnishes and have, compared to the plastic masses a very high thermal resistance, For example be Plastic masses such as polyethylene, polyvinyl chloride and polypropylene at 40 to 150 ° C soft and melt at 110 to 190 ° C. A formaldehyde lacquer coating will, however only at temperatures above 180 ° C and a polyamide lacquer coating only at temperatures soft above 300 ° C. That is why the formaldehyde lacquer and polyamide lacquer coatings are used If the plastic mass becomes soft, it still has a high insulation resistance.

A coating of aluminum oxide can also act as the first insulating layer be used because it has a greater thermal resistance than the ones to be connected Plastic masses. For example, an aluminum-coated wire such as that used for the Windings of electrical machines is suitable for the connection method according to the invention to be used. A coating made of aluminum oxide has a very high heat resistance and a sufficiently high insulation resistance even at temperatures around 300 ° C. It also has the advantage of good thermal conductivity.

Electric heating wires with double insulation according to the invention can be achieved by applying a second insulating layer 8 of almost the same Plastic material such as the plastic mass to be connected to the surface of the with a wire provided with a first insulating layer of high thermal resistance a obtain. If such a heating wire is wound around the plastic pipes, plastic material must be used be present to the Gaps between the electrical Heating wires a, which, as described above, have an insulating layer of great heat resistance have to fill in so that the neighboring heating wires with melted plastic mass are connected and thus greater strength and greater airtightness is obtained at the junction.

If lacquer or aluminum oxide coatings for the first insulation coating 7 are used, which have a greater thermal resistance than those to be connected Have plastic masses, these coatings are very useful for the method according to the invention be made thin, for example in the case of paint coatings less than 60 micromillimeters and less than 30 microns for aluminum oxide coatings. That's why you can achieve a very large winding factor even if the electric heating wires overlap. The dimensions of the insulating layer are so small Part of the entire connection cross-section that can be neglected and therefore the connection is very airtight.

Furthermore, the lacquer coatings combine very closely with the plastic masses, and the aluminum oxide coatings have a pordse surface, so that they are very closely also with plastic masses like polyethylene, which is comparatively bad with Metal connects, connects. The close connection of these coatings with the one to be connected Material contributes significantly to the airtightness of the connection.

Fig. 4 shows an example of a band-shaped electrical heating wire, which was created by combining several heating elements into one body. Fig. 3 shows a section through this body. In the ribbon-shaped electric heating wire a number of the above-described insulated heating wires a are arranged in parallel. The surface of the heating wires arranged in this way is covered with a second insulating layer 8 covered, which consists of almost the same plastic material as the one to be connected Plastic masses.

With this ribbon-shaped electrical heating wire, the effort can be reduced Winding work that is necessary to wrap the heating wire around the connecting plastic tubes must wind, compared to the effort for winding a single heating wire, be significantly downgraded. This is particularly beneficial when there is a connection in a narrow and dark manhole or when a pot connection is made want to be

The connection method shown in Fig. 1 relates to the connection of overlapping plastic tubes. Another method shown in FIG refers to the connection of butting plastic tubes of the same diameter.

It is particularly advantageous that the plastic tubes are similar Diameter can be connected directly to each other without a connecting sleeve.

As shown in Fig. 5, the ends of the plastic pipes 9 and 10 are tight joined together. An intermediate piece 11 made of metal is inserted on the inner walls. On the surface there is a single or band-shaped insulated pipe around the plastic pipes electrical heating wire 12 wound. A plastic layer 13 made of almost the same Material such as the plastic tubes 9 and 10 is attached to the heating wire. The plastic layer 13 is pressed with the fastening tape 14, such as a rubber band, the electrical flow Current through the heating wire 12, the plastic tubes 9 and 10 melt through connection the pipe ends and the plastic layer 13 su a body.

According to this connection method, the plastic pipes become without a connection socket connected in a simple and economical way. To make the plastic layer 13, it is convenient to wind up plastic tape or the plastic mass in the liquid state splash on. The intermediate piece 11 is intended to prevent the plastic mass in the connection area buckles inwards. It is beneficial to use a metal ring and this one Pull out again after the connection is complete. Furthermore, the plastic layer, as shown in Fig. 6, can also be attached under the heating wire, or et can Housing above and below the hot wires are attached to the connection make it safer.

FIG. 7 shows another exemplary embodiment for that in FIG. 5 shown Procedure. A metal band that attaches to a. Plastic layer that is almost the same Plastic material is made up of how the plastic tubing that is rolled is on the surface attached to the plastic pipes to be connected. In the process of connecting contiguous Tubes according to Fig. 5 and 6, the plastic mass is soft and caused by the expansion due to the pressure created by the heating in the connection area the electric heating wires move through the liquid plastic mass, and sometimes they can emerge on the inner surface of the plastic tubes. In this case you can small air holes, created by the heating wires, the inner and outer surface of the Connect plastic pipes. In this way, the airtightness may deteriorate will. This risk can be reduced if, as shown in FIG. 7, a metal layer is provided. According to this method, the ends of the plastic pipes 9 and 10 placed together, inserted the intermediate piece 11 on the inner surface and a Metal band 15, which is rolled onto a plastic layer, which is almost the same Material, like the plastic material, is made on the outer surface of the joint is attached, applied. A single or ribbon-shaped, doubly insulated electrical wire 12 of the type described above, is wrapped around the layer, and the plastic layer 13 made of almost the same material as the plastic pipes 9 and 10 is applied to the electrical heating wires. This is done with the wrapping tape 14 attached, which presses the plastic layer in place. When electrical current passes through the Heating wire flows, the plastic pipes 9 and 10 are made by connecting their ends and the plastic layer 13 welded to form a body.

The metal band 15 prevents the electrical heating wires 12 step out in the connection area on the inner surface of the plastic pipes. the Wires are after completion of the connection as shown in Fig. 8, in the plastic mass embedded and closely connected to it. There are definitely no air holes caused by the electrical heating wires, present that make up the inner surface and join the outer surface of the plastic tubes. As the electric heating wires have insulation with greater thermal resistance than the plastic masses, there is no risk of a short circuit between the heating wire windings and the metal strip. The metal band 15 is closely connected to the plastic tubes 9 and 10. It's on a Plastic layer rolled on, which is made of almost the same material as the Plastic tubes 9 and 10. Although it is cheaper to use a metal band, on a plastic layer is rolled on both sides, a metal band can also be used on which a plastic layer is rolled on only one side.

In this case, the tape must be wound up so that it is rolled up Plastic layer is on the surface of the plastic tubes.

The plastic layer can be pressure welded onto the metal strip 15 from Liquid plastic compound and metal tape, for example made of copper, aluminum, etc. applied will. For example, a tape was made for connecting polyethylene pipes 50 micron thick aluminum foil is used on the liquid polyethylene was rolled on at about 300 ° C in a thickness of 30 micromillimeters. The rolled up The layer was sufficiently welded to the metal surface. This was the result of peeling tests a peel strength of 600 g / omega, so that no air channels between metal foil and a rolled-on plastic layer.

Fig. 9 shows another embodiment of the invention in which the connection of the plastic-sheathed cables by combining the overlapping Connection of plastic pipes according to Fig. 1 and the abutting connection according to FIG. 5 takes place. As shown in FIG. 9, there are 18 on the plastic jackets and 19 of the plastic-sheathed plastic pipes 16 and 17 protruding susditsliche Plastic bushings 20 and 21 pushed on and between these and the plastic pipes the previously mentioned double-insulated heating wires 12 and 12 'or the band-shaped one Wire inserted. The other ends of the plastic bushings 20 and 21 are close to each other.

The welding of the ends 22 and 23 of the additional bushings 20 and 21 is generated by the electrical connection flowing through the electrical heating wires 12 and 12 ' Current is achieved while printing the overlapping ends. After that will be the electrical heating wires 12 "which are double insulated like the above to! the butting ends 24 and 25 of the additional sockets 20 and 21 wound, and over these electric heating wires 1211 a plastic layer 26 of almost the same material as the additional bushings 20 and 21 attached. about this a rubber band 27 is wound to keep the surfaces to be joined under pressure. The connection of the plastic-coated cables is brought about by the electric current, which is sent through the electrical heating wires 12 "so that the abutting Ends 24 and 25 of the additional sockets 20 and 21 and the plastic layer 27 together be welded.

In the method of connecting plastic pipes described above the winding work for applying the electrical heating wires can thereby be switched off that plastic connection sockets with contained double insulated Heating wires of the type described above or electric heating wires that are connected to a Material of high thermal resistance are insulated without plastic insulation layer, embedded in such material can be used. Embodiments for these types are shown in Figs. These show examples of the Connection sockets, in the inner circumference 29 of which the electrical heating wires 28 are embedded are. Fig. 12 shows an example of a connection with a socket according to Fig. 10. The ends 29 and 30 of the plastic pipes to be connected are placed close together, and the socket 31 in which the electric heating wires 28 are embedded is over the contiguous Ends pushed. To the socket 31 is a Fastening tape 32 wrapped. Electric current flows through the supply lines 33 and 34 through the electrical heating wire 28, the connection is made by heating and welding the ends of the plastic tubes 29 and 30 and the socket 31. Also in In this case, the intermediate piece 11 can be inserted to prevent the Plastic compound kinks inwards in the connection area.

A socket as shown in Fig. 11, in which the electrical Heating wires embedded at both ends of the inner perimeter can be used be to the plastic-sheathed cables 36 and 37, with those in the separation area 35 the cable core is exposed, according to FIG. 13, to connect.

Sockets with embedded electrical heating wires can also do differently be constructed as described above. They can be structured in such a way that with them a connection of a branch joint of plastic pipes and a connection by sealing closures of plastic cables.

When connecting waterproof cables such as Stalpeth cables, it is very important to have a watertight joint area. In which The connection method described above uses a plastic bushing in the connection area attached, in which the waterproof metal layer in the separated part of the cable core cut away was so that the water tightness only from the plastic socket in the connection area depends. However, since the moisture easily penetrates plastic, this method has the disadvantage that the insulation resistance of the wires in the cable due to moisture which penetrates and through the plastic bushing over the years gelant the separated part of the cable core into the interior of the cable. Since very often Water evaporating in the manholes through which the cables are passed can cause a significant amount of moisture penetrating through the plastic bushing in the joint area. Calculations were made for a Stateth cable with an outside diameter of about 67 mm. There was a 3 mm thick polyethylene socket on the cable in the connection area, 100 mm inside diameter and 600 mm length applied, and it was a temperature exposed to 20 ° C and 100 ° / o humidity. The result was that with one assumed moisture penetration coefficient for polyethylene of 0.5 - 0.5 x 10-9 (gcm / cm2 h mmHg) in the year 0.4-0.5 g of water vapor penetrates and that in the course of Years a considerable amount penetrates. Gemmas the method according to the invention this disadvantage can be avoided.

Fig. 14 shows an example of such a waterproof connection. The Stalpeth communication cables 38 and 39 to be connected are with the watertight Metal layers 42 and 43 on the inner surfaces of the plastic jackets 40 and 41 provided, and the connection area of the cables is waterproof Plastic socket 44 provided. Their ends 45 and 46 are over the plastic sheaths 40 and 41 pushed, and between the ends and the jackets are those described above double insulated hot wires 12 and 12 'wound. The connection is made by the electrical current that flows through the electrical heating wires and through which the Plastic sheaths 40 and 41 and the bushing 44 welded together, made.

The socket 44 used in this embodiment is shown in Fig 15 shown. It consists of the plastic tubes 45, which are made of almost the same Material such as the plastic sheaths 40 and 41 to be connected exist, and between which the metal layer 46 is embedded.

The production of the socket 44 can be carried out, for example, as follows : Spraying liquid plastic compound onto the outer and inner surfaces of a thin Wind up the metal sleeve or spiral wrapping according to FIG. 17 or lengthways of metal strip 47 with rolled-on plastic compound on the surface of a plastic pipe, to form a tube, as shown in Fig. 18, and weld it onto the metal layer rolled plastic sheet 49 with the plastic tubes 48 and 50.

The waterproof sockets described above are plastic sockets, in which the metal layer is embedded. Other examples demonstrate 19 and 20. These sockets are made of plastic tubes in which the metal layer attached to the inner or outer surface.

A connection area with one of the watertight ones described above Bushings shows good water tightness. Penetration tests on polyethylene bushings with and without moisture protection gave the following results. The test piece consisted of an aluminum strip 0.05 mm thick, on the polyethylene of 0.1 mm thick was applied and which had a width of 60 mm. This tape became wound on a plastic tube 2 mm thick, 1/3 overlapping. Over it was 2 mm polyethylene injected, so that a socket with an outer diameter of 60 mm was created.

This socket was made with a polyethylene socket with a wall thickness of about 4 mm and 60 mm outside diameter. The penetrating amount of steam is called water of 20 ° C. The test results are shown in Table 1.

Table 1 PolyEthylene bushing penetrated amount with moisture protection 1.0 x 10 D g / m min Without moisture protection4, 5 x 10 g / m min As the test results clearly show, only about 1/5 of the amount penetrates through a polyethylene socket with moisture protection, which penetrates through a polyethylene socket without moisture protection.

Fig. 21 shows another example of a waterproof connection of plastic-sheathed cables. A waterproof plastic bushing 52 is over the connection area 51 attached to the cable core. In this case, plastic bushings are rolled on Metal layer 53 as shown in Fig. 22 and Fig. 23 is used. at In the embodiment shown in FIG. 21, a socket was used, such as it is shown in FIG. It was made from a plastic tube with a rolled metal layer on it 53 made on the outer surface.

To make a connection area as shown in Fig. 21, was the separated area 51 of the cable core with the plastic tube 52, on which, as shown in FIG. 24, a metal layer 53 is rolled on. On the A metal layer 53 has been rolled on to the outer surface of a P-plastic tube 52 As shown in FIG. 25, pipe was attached to both ends of the plastic jacket 54 and 55 where the heating wires or the heating iron were attached, folded with it the plastic layer 52 with the cable sheathing 56 and the plastic layer 52 itself The plastic tube is connected to the ends of the cable sheathing xird. After applying the metal-coated Plastic pipe the cable core in the connection area, becomes the plastic socket 57 over the connection area appropriate.

Both ends of this socket are made following the procedure described above welded with the help of heating wires, so that you get a connection like them is shown in FIG.

The production of a metal-covered plastic pipe can preferably as follows: A plastic sheet made of a polyethylene layer 25 is made, as shown in Fig. 26, welded to a metal foil 53 and formed into a tube with the Polyethylene layer molded inside. The polyethylene layer is at the seam welded by heat. Metal-covered plastic plates, as shown in Fig. 26, are produced by roll pressing, with the liquid plastic mass on a Metal foil, for example made of aluminum or copper, is applied and wherein a sufficient peelability between the layers is achieved, pipes according to Fig. 23 will be. by applying liquid polyethylene layers on both sides the metal foil is generated, while in the case of the tubes according to FIG. 22 only on one side Liquid polyethylene is applied to the metal foil. In this example, Applied to an aluminum foil of 0.05mm thickness 0.05mm polyethylene. the the resulting peel strength was greater than the tear strength of the polyethylene film.

Attaching a plastic pipe in the connection area of the cable core can be done simply in that a plate as shown in FIG. 26 cylindrically around the Connection area is wound, so that a tube as shown in FIG. 22 is formed. It is but also possible to produce the metal-covered plastic tube beforehand and then on push the cable to the junction.

If the cable is to be sealed gas-tight, this is described above Plastic pipe about the same size as the plastic bushing over the pipe made so the pipe does not when the gas expands between the pipe and the outer plastic bushing is destroyed. Because the outer plastic bushing provides the mechanical strength of the connection supplies, the plastic pipe can be made very dU =. In this case one was sufficient Thickness of 0.1 mm.

Although some exemplary embodiments of the invention have been described above are, in the following some test results of connections plastic-coated Cables are specified.

The connection shown in Figure 27 connects Stalpeth cables to it 0.65 mm x 1,000 wire pairs. The test results are shown in Table 2.

Table 2 Type of test Test method Test result =================================================== ========= Tensile load applied at AB according to Fig. 27 ZerreiBlast 850 kg Tensile test load increase 50 kg Breaking point Duration of each load additional socket 100 min Inner gait pressure 1 kg / cm2 Temperature change No result after sel attempt 10 changes temperature - 40 ° C @ 60 ° C Internal gas pressure 1 kg / cm Load 100 kg No result after Oscillation 700 hours search. Frequency 800 Hz Amplitude ~ 2 bm Inner gas through No result after 2 kg / cm2 50 hours As the test results show, the loading tests gave surprisingly good results for the method according to the invention.

As described above, the invention relates to a number of methods for connecting plastic pipes (especially plastic-sheathed cables) with the help of electric heating wires. These procedures have the great advantages of being simple Application, making a reliable connection and low cost.

Claims (23)

Claims 1. A method for connecting plastic pipes, thereby characterized in that the nested ends of the plastic tubes (e.g. 2 and 4) with the help of intermediate electrical heating wires (e.g. 3) through which Electric current flows through which the resulting heat is welded together and that the electrical heating wire (6) with a double insulating layer (7 and 8), which consists of an inner insulating cover (7) with greater thermal resistance than the plastic material of the plastic pipes and that consists of an outer insulating coating (8) is made of almost the same plastic material as the plastic tubes. 2. The method according to claim 1, characterized in that the heating wire consists of a number of heating wires (6), each with an internal insulating cover (7) With a greater heat resistance than the plastic material of the plastic pipes be provided that the wires (6) parallel to each other at the desired intervals and that an outer plastic layer (8) made of almost the same Plastic material such as the plastic tubes for connecting the individual wires (6) to a band-shaped heating wire is attached. 3. The method according to claim 1 or 2, characterized in that the to be connected plastic pipes made of plastic sockets and / or plastic sheaths of the plastic-sheathed cables (e.g. 3 and 4) exist. 4. Verfanren according to claim 1 or 2, characterized in that the to be connected plastic pipes consist of plastic pipes. 5. The method according to claim 1 or 2, characterized in that the to be connected plastic tubes (z. B. 9 and 10) with their ends butting against each other be arranged that the electrical heating wire (z. B. 12) wrapped around the ends becomes that over the heating wire (z. B. 12) a plastic layer (z. B. 13) from almost the same material as that of the plastic pipes (e.g. 9 and 10) and is pressed and that by the heat generated by the electric current, the ends of the plastic tubes (e.g. 9 and 10) and the plastic layer (e.g. 13) together be welded. 6. The method according to claim 1 or 2, characterized in that the to be connected plastic tubes (z. B. 9 and 10) with their ends butting against each other be arranged so that around both ends a plastic layer (e.g. 13) made of nearly the same material as that of the plastic tubes (e.g. 9 and 10) wrapped that around this plastic layer (e.g. 13) the electric heating wire (e.g. 12) is wrapped and pressed tight and that the generated by the electric current Heat the ends of the plastic tubes (e.g. 9 and 10) and the plastic layer (e.g. 13) are welded together. 7. The method according to claim 5 or 6, characterized in that first A metal tape (e.g. 15) is wound over the ends of the plastic tubes (e.g. 9 and 10) on which a plastic layer made of almost the same material as the plastic pipes is upset. 8. The method according to any one of claims 5 to 7, characterized in that that as an electrical heating wire (e.g. 12) wire (6) with double insulation (7 and 8) is used and that the inner insulating cover (7) made of a material with greater thermal resistance than that of plastic tubes (e.g. 9 and 10), while the outer insulating cover (8) is made of almost the same material as the plastic pipes consists. 9. The method according to any one of claims 5 to 7, characterized in that that a band-shaped heating wire is used as the electrical heating wire (e.g. 12), the one from a Consists of a plurality of insulated heating wires (a), those with an insulating layer (7) made of a material of greater thermal resistance than that of the plastic tubes (e.g. 9 and 10), which are provided in the desired spacing are arranged parallel to one another and with an insulating layer surrounding them (8) made of almost the same material as the plastic pipes (e.g. 9 and 10) are. 10. The method according to claim 8 or 9, characterized in that the plastic tubes to be connected the plastic jackets (e.g. 18 and 19) of are plastic-sheathed cables (e.g. 16 and 17). 11. The method according to claim 8 or 9, characterized in that the plastic tubes to be connected plastic sockets (e.g. 20 and 21) s-dnd. 12. The method according to claim 8 or 9, characterized in that the plastic pipes to be connected plastic pipes (e.g. 9 and 10) are. 13. The method according to any one of the preceding claims, characterized in that that a lacquer coating is applied to the heating wires (6) as an inner insulating layer (7) will. 14. The method according to any one of claims 1 to 12, characterized in, that on the heating wires (6) as an inner insulating layer (7) an aluminum oxide coating is applied. 15. The method according to claim 13 or 14, characterized in that the heating wires (28) embedded in the inner wall (29) of plastic bushings (z. B. 31) will. 16. The method according to claim 15, characterized in that a plastic bushing (z. B. 31) with embedded heating wires (28) to connect two butting Ends of two plastic pipes (e.g. 29 and 30) are used, with the ends of the Plastic pipes (e.g. 29 and 30) and the plastic socket (e.g. 31) through the from the electrical Heat generated by electricity can be welded together. 17. The method according to claim 16, characterized in that the plastic bushing (e.g. 31) for welding to the plastic tubes (e.g. 29 and 30) firmly to them is pressed. 18. The method according to any one of claims 5 to 18, characterized in, that the plastic socket (z. B. 15) over the ends of the plastic tubes to be connected (e.g. 9 and 10) is attached from a thin plastic tube (e.g. 45) with a Metal layer (e.g. 46). 19. The method according to claim 18, characterized in that the used Plastic socket (z. B. 44) made of a metal band (z. B. 47) with at least one Side of applied plastic layer by winding in a spiral shape or lengthways and that a plastic tube (e.g. 50) is attached and welded to it. 20. The method according to claim 19, characterized in that as a metal strip (e.g. 47) an aluminum tape is used. 21. The method according to any one of claims 19 or 20, characterized in that that a first plastic socket (e.g. 52) containing a metal band (e.g. 53), applied to the separated area of the cable core (e.g. 51) and with the Plastic sheaths (z. B. 56) of the cable is welded airtight that a second Plastic bushing (e.g. 57) is fitted over the first bushing (e.g. 52) so that the ends of this second plastic socket (e.g. 57) over the first socket (e.g. 52) stand out and that the ends of the second plastic sleeve (z. B. 57) with the help of a Intermediate layer of heating wires (e.g. 12) welded to the plastic sheaths (e.g. 56) will. 22. The method according to any one of claims 7 to 21, characterized in that that the plastic bushing (e.g. 44) containing a metal layer (e.g. 46) from a Plate is made of an aluminum foil (e.g. 53) on which at least a layer of polyethylene (z. B. 52) is wired on one side, consists. 23. The method according to any one of claims 15 to 22, characterized in that that on the heating wires (6) as an inner insulating layer (7), which has a greater thermal resistance than the plastic mass to be connected, a lacquer coating or an aluminum oxide coating is applied.