DE20213973U1 - Connection section of a plastic pipe or container made of a thermoplastic - Google Patents

Description

HENZE GmbH Plastics Plant 5 September 2002

Josef-Kitz-Straße 9 Hw/kin (20020447)

53840 Troisdorf Q02557DE00

Connection section of a plastic pipe or container made of a thermoplastic material

Description

The invention relates to a connecting section of a plastic pipe or container made of a thermoplastic material, in particular a winding pipe made of a strip made of a thermoplastic material for connection to another plastic pipe made of a thermoplastic material.

DE 42 41 561 A1 describes a connecting section of a pipe in the form of an electrically weldable pipe connection point made of thermoplastic material, wherein in a first process step an incision is made in the pipe, namely in the inner surface of the connecting bore of the same, from which lateral incisions extend. In the flaps created by the incisions there is a recess for receiving a heating conductor. After folding back the flaps, the heating conductor can be inserted. These rest on it in order to fix it in the recess. The connection of the heating conductor to the surrounding material of the base body is achieved by heating the heating conductor and pressing a cooling surface against it in order to

to achieve a fusion of the interfaces and thus create a surface that is essentially free of grooves and smooth. The recess in the form of a groove is itself created by machining after the tabs created by the cuts have been folded away. The process described above is complex and not only weakens the profile in relation to the groove, but also beyond that due to the cuts.

The invention is based on the object of creating a connection section in which, on the one hand, the heating wire is securely fixed in the base body, and on the other hand, an introduction of the heating wire and the establishment of the connection thereof to the base body is made possible by simple means.

The object is achieved according to the invention by a connecting section of a plastic pipe or container made of a thermoplastic material, in particular a wound pipe made of a strip made of a thermoplastic material, for connection to another plastic pipe made of a thermoplastic material comprising

a base body,

- which is integral with the plastic pipe or container

trained and

- which has a connection surface of a predetermined length which is part of an inner peripheral surface of a connection bore or an outer peripheral surface in which there is at least one groove,

at least one heating wire,

- which has a core made of at least one metal wire forming an electrical resistance,

- whose core is enclosed in a sheath made of a thermoplastic material,

- which is at least partially received in the at least one groove with its casing, and

- whose casing is firmly bonded to the base body made of a thermoplastic material,

solved.

The advantage of this design is that one or more grooves for receiving the heating wire can be machined directly into the connection surface, i.e. into the inner circumferential surface of the connection hole or the outer circumferential surface of the connection section, without having to use special tools or means to ensure that the area in which the groove is to be made is kept free. In addition, it is ensured that the structure of the connection section is not weakened by cuts. Adequate fixation is achieved through the material connection of the heating wire sheath to the base body of the connection section.

Preferably, the casing and the base body are made of the same thermoplastic material. This ensures that an intimate connection is made between the connecting section and the other pipe or its connecting section during the final connection process, since the casing also comes into contact with the connecting section because it is accommodated in the groove that is open towards the connection hole. A design in which the cross-section of the groove and that of the heating wire are adapted to one another is advantageous.

The material bond is conveniently achieved by

The result is that the casing is connected to the base body under the influence of heat. This is made possible simply by pressing the heating wire with the casing into the groove while simultaneously melting the surfaces of the casing. The melting of the surface can be done using hot air.

A particularly advantageous design is achieved when the casing projects over the connection surface with part of its circumference. When the connection section is connected to the corresponding associated connection section of the other pipe, particularly when radial pressure is exerted, the protruding material of the casing flows into the gaps adjacent to it at the side.

In an embodiment of the invention, the groove can be machined into the connection surface in a simple manner.

A preferred embodiment of the invention is shown in the drawing.

Preferred embodiments are explained in more detail below with reference to the drawings.

Fig. 1 is a perspective view of two plastic pipes connected to each other;

Fig. 2 shows a partial longitudinal section through a connecting arrangement with a connection section and a connecting section in the unconnected state;

Fig. 3 shows the connection arrangement according to Fig. 2 in the connected state;

Fig. 4 is a schematic representation of the circuits of the resistance heating wires;

Fig. 5 shows a partial longitudinal section through a connection arrangement with a test channel in the unconnected state and

Fig. 6 is a partial longitudinal section of a connecting arrangement according to Fig. 5 in the connected state.

In Fig. 1, a plastic pipe 1 is shown in partial section. The plastic pipe 1 is arranged coaxially to a longitudinal axis 3 and has a cylindrical inner surface 4 for transporting liquid media. At one longitudinal end, the plastic pipe 1 has a connection section 2. The plastic pipe 1 also has a first pipe body 5 and a second pipe body 6 arranged around it. The first pipe body 5 is made from a strip of a thermoplastic material using a winding process. The second pipe body 6 is made from a hollow profile 7 wound around the first pipe body 5, the hollow profile 7 having a square cross-section. The second pipe body 6 serves to stabilize the plastic pipe 1.

The plastic pipe 1 is connected via the connection section 2 to a connecting section 8 of another plastic pipe 9. The other plastic pipe 9 also has an inner surface 10 arranged coaxially to the longitudinal axis 3, which, when the plastic pipes 1, 9 are connected, merges flush into the inner surface 4 and serves to transport liquid media. The other plastic pipe 9 is also made of a cylindrical first pipe body 11 and a second pipe

it»

body 12 made of a hollow profile 13.

The connection between the connection section 2 and the connection section 8 is explained below, together with Figs. 2 and 3. The connection section 2 comprises a base body 14 and a resistance heating wire 15. A connection bore 16 is made in the base body 14, which forms a first circumferential surface in the form of a conical inner circumferential surface 17. A helical groove 18 is made in the inner circumferential surface 17. The resistance heating wire 15 is placed in the groove 18 so that it only protrudes slightly beyond the inner circumferential surface 17.

The resistance heating wire 15 has a core 19 made of a metal wire that forms an electrical resistor. The core 19 is enclosed by a sheath 20 made of a thermoplastic material. During the manufacture of the connection section 2, the sheath 20 is heated and pressed into the grooves 18. This can be done, for example, with hot air, with the resistance heating wire 15 being pressed into the groove 18 with a roller. The sheath 20 and the base body 14 are preferably made of the same plastic. This ensures that the resistance heating wire 15 is firmly connected to the connection section 2 so that it cannot be loosened during transport or when pushed onto the connection section 8.

The connection bore 16 has an opening 21 through which the connecting section 8 of the further plastic pipe 9 can be introduced into the connection bore 16. The inner circumferential surface 17 widens in the direction of the opening 21. The connection section 2 has a first end face 22 at the opening 21, which merges into the inner circumferential surface 17. The inner circumferential surface 17 merges at the first end face

22 spaced axial end of the inner peripheral surface 17 into a first contact surface 23 which is arranged around the longitudinal axis 3.

The connecting section 24 of the further plastic pipe 9 has a second circumferential surface in the form of an outer circumferential surface 25, which is designed opposite to the inner circumferential surface 17. A second end face 27 is provided on a free end of the further plastic pipe 9, which merges into the outer circumferential surface 25. At the axial end of the outer circumferential surface 25 arranged remote from the second end face 27, the latter merges into a second contact surface 26.

When the connecting section 8 is pushed in (Fig. 3), the inner peripheral surface 17 is in contact with the outer peripheral surface 25. Furthermore, the first end face 22 and the second contact surface 26 as well as the first contact surface 23 and the second end face 27 are each in contact. Due to the conical shape of the inner peripheral surface 17 and the outer peripheral surface 25, the insertion of the connecting section 8 into the connection bore 16 is made easier. Furthermore, it is ensured that there is no radial play between the inner peripheral surface 17 and the outer peripheral surface 25, which could lead to air inclusion and impair the welding. Furthermore, by supporting the first end face 22 against the second contact surface 26 and by supporting the first contact surface 23 against the second end face 27, a tightening limitation is ensured, which prevents an overload in which high radial forces would occur due to the conical inner circumferential surface 17 and the conical outer circumferential surface 25, which would result in excessive deformation of the connection section 2 and the connecting section 8.

In order to axially secure the plastic pipe 1 and the further plastic pipe 9 when the connecting section 8 is pushed in, the base body 14 forms a first support surface 29 facing away from the connecting section 8. The connecting section 8 has a corresponding second support surface 30 which faces away from the first support surface 29. In this way, clamping elements can be provided which are supported against the first support surface 29 and the second support surface 30 and apply an axial force so that a joining pressure prevails between the inner circumferential surface 17 and the outer circumferential surface 25, which is necessary for secure welding.

After the connecting section 8 has been inserted into the connection bore 16 and the connecting section 2 and the connecting section 8 have been axially clamped, the resistance heating wire 15 is connected to an electrical power source and heated due to the electrical resistance of the core 19. The melting temperature of the plastic is reached so that a melting area 28 is formed in which the material of the connecting section 2 and the material of the connecting section 8 are thermally bonded to one another.

Several helical shafts 18 can also be provided, in which several resistance heating wires 15 are inserted. Fig. 4 shows a schematic representation of the circuit structure in the case where two resistance heating wires 15, 15' are provided. Both resistance heating wires 15, 15' are helical and each have a first electrical connection 31, 31' and a second electrical connection 32, 32'. The two first electrical connections 31, 31' are connected together to a first electrical connection pole 23. The second electrical connections 32, 32' are connected together to a second electrical connection pole 34.

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The two electrical connection poles 33, 34 can be connected to conventional welding devices.

Fig. 5 and 6 show a partial longitudinal section through a connection arrangement with two resistance heating wires. Components that correspond to components of the connection arrangement according to Fig. 2 and 3 are provided with the same reference numerals and are described there.

The two resistance heating wires 15, 15' are laid in a spiral shape in two grooves 18, 18' of the inner circumferential surface 17. The two resistance heating wires 15, 15' are arranged one behind the other at an axial distance. A circumferential annular groove 35 is made in the inner circumferential surface 17 between the resistance heating wires 15, 15'. The annular groove 35 is connected to a connection hole 36 in terms of pipework. The connection hole 36 is in turn connected to a valve 37, via which the connection hole 36 can be closed off to the outside. A compressed air source can be connected via the valve 37, so that the annular groove 35 can be pressurized with compressed air after welding. The annular groove 35 and connection hole 36 can then be closed off to the outside and checked after a predetermined time whether a pressure drop has occurred. If the pressure drop does not exceed a specified limit, it is ensured that the welding was carried out correctly.

·

HENZE GmbH Plastics Plant 5 September 2002

Josef-Kitz-Straße 9 Hw/kin (20020448)

Q02557DE00 53840 Troisdorf

Connection section of a plastic pipe or container made of
a thermoplastic

List of reference symbols

1 Plastic pipe 2 Connection section 3 Longitudinal axis 4 Inner surface 5 first pipe body &bgr; second pipe body 7 Hollow profile 8th Connecting section 9 additional plastic pipe 10 Inner surface 11 first pipe body 12 second pipe body 13 Hollow profile 14 Base body 15, 15' Resistance heating wire 16 Connection hole 17 Inner peripheral surface :..'·:... .:*.. ^! .. ^: ·*.'·· ··· *··'

III· ΦΦΦ·

φ φ · φ φ ·

ϕ ϕ ϕ · ·

-••«•&igr;.:"tü.rv;: ^!

18, 18' groove

19 Soul

20 Wrapping

21 Opening

22 first front surface

23 first contact area

24 Connecting section

25 Outer peripheral surface

26 second contact surface

27 second front surface

28 Melting area

29 first front surface

30 second front surface

31, 31' first electrical connection

32, 32' second electrical connection

33 first electrical connection pole

34 second electrical connection pole

35 Ring groove

36 Connection hole

37 Valve

Claims (6)

1. Connection section of a plastic pipe or container made of a thermoplastic material, in particular a wound pipe made of a strip made of a thermoplastic material, for connection to another plastic pipe made of a thermoplastic material, comprising - a base body ( 14 ), - which is formed in one piece with the plastic pipe ( 1 ) or container and - which has a connection surface of a predetermined length which is part of an inner peripheral surface ( 17 ), a connection bore ( 16 ) or an outer peripheral surface in which at least one groove ( 18 , 18 ') is located, - at least one heating wire ( 15 , 15 '), - which has a core ( 19 ) made of at least one metal wire forming an electrical resistance, - whose core ( 19 ) is enclosed by a covering ( 20 ) made of a thermoplastic material, - which is at least partially received in the at least one groove ( 18 , 18 ') with its casing ( 20 ), and - whose casing ( 20 ) is materially connected to the base body ( 14 ) consisting of a thermoplastic material. 2. Connection section according to claim 1, characterized in that the sheath ( 20 ) and the base body ( 14 ) consist of the same thermoplastic material. 3. Connection section according to one of claims 1 or 2, characterized in that the cross section of the groove ( 18 , 18 ') and that of the heating wire ( 15 , 15 ') are adapted to each other in terms of shape. 4. Connection section according to one of claims 1 to 3, characterized in that the sheath ( 20 ) is connected to the base body ( 14 ) under the influence of heat. 5. Connection section according to one of claims 1 to 4, characterized in that the sheath ( 20 ) projects beyond the connection surface ( 17 ) with a part of its circumference. 6. Connection section according to one of claims 1 to 5, characterized in that the groove ( 18 , 18 ') is machined into the connection surface ( 17 ).