DE202011051981U1 - socketweld - Google Patents

Abstract

Electrowelding sleeve comprising a basically cylindrical tubular sleeve body made of plastic, in which at least one spiral heating wire is embedded in the longitudinal direction, characterized in that at least one heating wire (12) enclosed by plastic is arranged at least in a section of the sleeve body (10) in such a way that the distances between adjacent turns of the spiral-shaped heating wire gradually decrease or increase in the longitudinal direction.

Description

The present invention relates to an electrofusion joint comprising a basically cylindrical tubular sleeve body made of plastic, in which at least one spirally extending in the longitudinal direction heating wire is embedded.

Electric welding sleeves with helically arranged heating wire and their use for welding plastic pipes are basically known from the prior art. As an example in this context, the DE 197 52 910 A1 directed. In the conventional electric welding sleeves, the heating coil usually extend in the region of the inner surface of the sleeve, wherein the heating wire is laid so that it spirally winds at a distance around the longitudinal axis of the sleeve and wherein the distances of the successive turns of the spiral arrangement regularly and on the Length of the sleeve are uniform. This has the consequence that a combination of Heizelementstumpf- and Heizwendelschweißen is required for certain pipes. Such a combination is particularly necessary to seal the faces of the tubes and to prevent, for example, in a multilayer tube during operation of the pipeline, a breakdown of the medium through the outer layer of the tube. This combined process is complex and sometimes technically difficult to implement.

The WO 02/11973 A1 describes a device for connecting components of a fuel line, comprising three components, namely an outer member having a socket formed on a tank, which serves as a sleeve, an inner member in the form of a tube with a conical portion and a third component, which is concentrically received in the annular gap between the other two components. The third component is formed as an electric welding sleeve and also has a conical portion corresponding to the cone of the inner tubular member. In the body of the third component run heating coil, which also extend into the conical section. Thus, the helically extending wire in this section has a conical course seen in the axial direction of the tube, which, however, follows the conical shape of the tube itself.

Starting from the above-cited prior art, it is an object of the present invention to provide a heating coil sleeve by means of which it is possible simultaneously to seal the ends of multilayer pipes and to absorb the forces resulting from the internal pressure of the fluid passing through the pipe.

The object of the present invention is to provide an electric welding sleeve with the features of the aforementioned type, in which a different penetration depth of the welding energy can be achieved during the electric welding in different areas of the sleeve body.

The solution to this problem provides an electric welding sleeve of the aforementioned type with the characterizing features of the main claim.

According to the invention, at least one heating wire enclosed in plastic is arranged at least in a section of the sleeve body in such a way that the spacings of adjacent turns of the spirally laid heating wire gradually decrease or increase in the longitudinal direction.

An alternative solution of the aforementioned object or a development of the aforementioned task solution provides that at least one embedded in the plastic of the sleeve body heating wire extends with a conical spiral shape in a cylindrical portion of the sleeve body.

In both aforementioned variants of the solution, it is possible to vary the welding energy transferable per effective area of the sleeve in different sections of the sleeve. In the case of the former alternative, the decreasing spacing of adjacent turns of the heating wire increases the number of heating wire windings per unit area and thus the heating wire length per unit area of the socket welding surface, thus increasing the transmittable welding energy. In the case of the second mentioned alternative, with decreasing radius of the respective turns of the heating coil, the heating wire can move closer to the axis of the sleeve and thus closer to the effective cylindrical inner surface of the welding sleeve, so that the transmittable welding energy also increases. It is also possible to combine the two alternatives mentioned above to produce the desired effect.

Preferably, it is provided in the context of the present invention that a so-called conical spiral course of at least one heating wire is given by a heating wire embedded in the sleeve body having a plurality of successive turns, in which each of the subsequent turns seen in the longitudinal direction of the sleeve body has a smaller one Winding diameter than the previous turn, but with adjacent turns run concentrically to the central axis of the sleeve body.

According to a possible embodiment variant of the present invention, it may for example be such that in the longitudinal direction of the sleeve body in each case reducing or increasing distances between each two adjacent turns of a heating wire, the winding diameter of adjacent turns, preferably the winding diameter of all turns, based on the center axis of the sleeve body stay constant.

According to a possible alternative embodiment variant of the present invention, it may also be the case, for example, that in the longitudinal direction of the sleeve body decreasing or increasing distances between each two adjacent turns of a heating wire, the winding diameter of adjacent turns seen in the longitudinal direction of the sleeve body also decrease or increase. In this exemplary case, two aforementioned variants according to the invention are thus combined with one another. The welding energy that can be introduced into the socket body is thereby increased by two effects, firstly by the increasing density of the windings following one another in the longitudinal direction (axial direction) and secondly by the windings being closer to the inner surface of the socket body due to the decreasing diameter.

If, for example, it is envisaged that the respective distances of two adjacent turns of the heating wire from a central region of the sleeve body decrease in the longitudinal direction to a front end of the sleeve body, then you can in the region of the front end by the reduction of the Heizdrahtabstände a stronger heating and thus a melting and sealing the ends of a tube inserted into the sleeve body, for example, achieve in one operation. This is particularly advantageous for the sealing of the face ends of a multilayer pipe, since this eliminates the need to seal the boundary between two layers, otherwise a fluid carried in the pipe could penetrate this boundary and thus between the layers. The simultaneous sealing of the front ends saves additional welding operations.

According to a preferred development of the task solution according to the invention, the heating wire laid in a sleeve body can consist of several separate heating coils which can be heated independently of one another. Thus, when referred to herein as "the heating wire," that does not mean that it refers to a single heating wire alone, but also includes a set of several separate heating wires. This separation allows further degrees of freedom in the arrangement of the heating wire in order to achieve different degrees of heating in different sections of the sleeve body. For example, here a first heating coil, which has a greater distance from the front end of the sleeve body, carry the load resulting from the internal pressure of the pipeline, while a closer to the front end arranged second heating coil causes the sealing of the end faces.

Alternatively or simultaneously, for example, a plurality of mutually independently heated heating coil in the sleeve body can be laid so that at least one turn of a first heating coil seen in the longitudinal direction of the sleeve body between two heating coils of a second heating coil is arranged.

If in the present application, it is mentioned that the heating coil (s) or heating wires are "embedded" in the plastic of the sleeve body, this does not necessarily mean that the heating coil or the heating wire at a distance from the surface in the plastic, so in Interior of the sleeve body is located. Heating coil or heating wire need not be completely enclosed by the plastic of the sleeve body to fulfill the function of the invention. Rather, the heating coil or the heating wire can also be located on the surface of the sleeve body and possibly also partially protrude from the plastic of the sleeve body. Embodiments in which the heating coils are thus not completely covered by the plastic are thus also included in the definition "embedded" and fall within the scope of the present invention. The position of the heating coil shown in the drawings is therefore to be understood only as an example.

The features mentioned in the dependent claims relate to preferred developments of the task solution according to the invention. Further advantages of the invention will become apparent from the following detailed description.

Hereinafter, the present invention will be described in more detail by way of embodiments with reference to the accompanying drawings.

Showing:

1 a simplified schematic view of a longitudinal section through a sleeve body according to a first alternative embodiment of the present invention;

2 a simplified schematic view of a longitudinal section through a sleeve body according to a second alternative embodiment of the present invention;

3 a simplified schematic view of a longitudinal section through a sleeve body according to a third alternative embodiment of the present invention;

4 a simplified schematic view of a longitudinal section through a sleeve body according to a fourth alternative embodiment of the present invention.

Subsequently, first on 1 Referenced. This shows a schematically simplified view of a longitudinal section through a sleeve body according to a first alternative embodiment of the present invention. It can be seen here a cylindrical tubular sleeve body 10 , which is intended, two pipes not shown here, the ends of each of the one side and from the other side in the cylindrical inner cavity 11 of the sleeve body are inserted in order to then electrically weld them together. These are pipes made of thermoplastic materials which soften when heated by the sleeve body, so that then a material connection between the outer circumference of the first tube and the inner circumference of the sleeve on the one hand and in the same way a corresponding connection between the outer circumference of the second tube and On the other hand, the inner periphery of the sleeve is formed at the other end of the sleeve, so that the two ends of the tubes are connected via the sleeve to a continuous pipe.

To the softened inner area of the sleeve body 10 to heat is in the sleeve body a heating wire 12 incorporated, which is embedded in the plastic of the sleeve body, wherein in the embodiment according to 1 the heating wire 12 radially comparatively far inside, in the vicinity of the cylindrical inner peripheral surface 13 of the sleeve body. The heating wire 12 includes a plurality of spirals about a central axis 14 meandering windings which extend concentrically to this central axis in the longitudinal direction of the sleeve body. The distances between individual turns of the helix or helix in the left in the drawing section, ie the left front end 15 towards, initially larger, that is, it results here per unit length of the sleeve body 10 relatively few turns of the heating wire 12 , To the other front end 16 down (in the drawing on the right) take the distances between the individual turns of the heating wire 12 so that the heating wire density per unit length and thus also the heating wire density per unit area of the inner peripheral surface 13 of the sleeve body (or in the vicinity) gradually increases. This results in that when passing an electric current through the heating wire 12 increases in the welding process in the sections with a larger number of Heizdrahttwindungen per unit length of the sleeve body in the registered heating energy. As a result, there is more heating there than in the more spaced turns. It can therefore be a demand differentiated heat input into the sleeve body in different areas during the welding process.

2 also shows a highly schematically simplified view of a longitudinal section through a sleeve body 10 according to a second alternative embodiment of the present invention. One recognizes that with the 12 designated heating wire here also consists of one or more heating coils, which spiral around the central axis 14 of the sleeve body 10 winds and which are embedded in the plastic of the sleeve body. While, however, in the variant of 1 the totality of the windings forms a quasi cylindrical spiral, since the diameters of the individual windings are constant over the length of the spiral, lies in the variant of 2 a conical spiral, so to speak. From the left in the drawing front end 15 starting to the right front end 16 towards the diameter of the turns of the spiral arrangement steadily decreases. This causes the turns of the heating wire 12 in the left area of the sleeve body 10 radially outward, while gradually gradually towards the right, radially inward toward the inner peripheral surface 13 lie down. The radius of the turns of the heating wire thus decreases from a front end 15 of the sleeve body 10 to the other front end 16 of the sleeve body gradually. The turns of the heating wire are thus closer to the front end 16 towards the inner peripheral surface 13 and consequently also lead to a stronger heating of one in the sleeve body 10 inserted pipe.

At the same time take in the embodiment according to 2 even from the right front end 15 starting to the left front end 16 towards the respective distances, in the longitudinal direction of the sleeve body 10 seen between two adjacent turns of the heating wire 12 so that the heating wire density per unit area also increases. This results in two effects that increase and both lead to an increase in the energy input during the welding process, namely, once the greater proximity of the heating wires to the inner peripheral surface 13 the sleeve body, with a smaller radius of the winding, and on the other hand, the increasing Heizdrahtdichte by the smaller distances between each two turns.

3 shows a further schematically simplified view of a longitudinal section through a sleeve body according to a third alternative embodiment of the present invention. In this variant, although the spiral of the heating wire 12 in the longitudinal direction of the sleeve body 10 seen conical, but the distances between each two adjacent turns of the heating wire 12 are constant over the length of the heating wire and thus in the longitudinal direction of the sleeve body. So this is the case here before 2 described effect that due to the smaller radii of the turns, the heating wires closer and closer to the inner peripheral surface 13 of the sleeve body 10 lie, whereby a stronger heating during the welding process is achieved. However, there is not the additional effect of increasing the heater wire density here because the pitches of the individual adjacent turns are the same.

4 shows a further schematically simplified view of a longitudinal section through a sleeve body according to a fourth alternative embodiment of the present invention. In this variant, the distances between adjacent turns of the heating wire 12 similar to the variant according to 1 in different areas of the sleeve body 10 differently. In a left front end 15 facing first area 17 are the distances between adjacent turns of the heating wire 12 approximately constant. Furthermore, the turns of the heating wire are comparatively close to the inner peripheral surface 13 of the sleeve body 10 , The energy entered during the welding process is thus in the range 17 approximately constant over the length of this range. In a second region spaced longitudinally therefrom 18 , which is more the right front end 16 of the sleeve body 10 In contrast, take the distances of adjacent turns of the heating wire 12 gradually, but the radius of the turns of the heating wire is constant and also with that in the first area 17 matches. As a result of the increasing density of the heating wires, the heat energy introduced into the sleeve body thus increases even if the radius of the turns remains constant. You can, for example, for the area 17 a first heating wire 12 use and for the second area 18 one independently heated second heating wire 12a use, so you have greater flexibility and the possibility exists, the first heating wire 12 and the second heating wire 12a each to heat independently of each other and optionally to apply different currents.

LIST OF REFERENCE NUMBERS

10

sleeve body

11

inner cavity

12

heating wire

12a

heating wire

13

Inner circumferential surface

14

central axis

15

left front end

16

right front end

17

first area (section)

18

second area (section)

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 19752910 A1 [0002]
• WO 02/11973 A1 [0003]

Claims (10)

Electrowelding sleeve comprising a basically cylindrical tubular sleeve body made of plastic, in which at least one spirally extending in the longitudinal direction heating wire is embedded, characterized in that at least one plastic-enclosed heating wire ( 12 ) at least in a portion of the sleeve body ( 10 ) is arranged such that the distances of adjacent turns of the helically laid heating wire gradually decrease or increase in the longitudinal direction. Electrowelding sleeve according to the preamble of claim 1 or claim 1, characterized in that at least one in the plastic of the sleeve body ( 10 ) embedded heating wire ( 12 ) extends with a conical spiral shape in a cylindrical portion of the sleeve body. Electric welding sleeve according to claim 1 or 2, characterized in that a in the sleeve body ( 10 ) embedded heating wire ( 12 ) has a plurality of successive turns, in which each of the following in the longitudinal direction of the sleeve body winding has a smaller turn diameter than the previous turn, but with adjacent turns concentric to the central axis ( 14 ) run the sleeve body. Electrowelding sleeve according to one of claims 1 to 3, characterized in that in the longitudinal direction of the sleeve body ( 10 ) each decreasing or increasing distances between each two adjacent turns of a heating wire ( 12 ) the turns diameter of adjacent turns, preferably the turns diameter of all turns, with respect to the central axis ( 14 ) of the sleeve body remain constant. Electrowelding sleeve according to claim 4, characterized in that in the longitudinal direction of the sleeve body ( 10 ) each decreasing or increasing distances between each two adjacent turns of a heating wire ( 12 ) the winding diameters of adjacent turns seen in the longitudinal direction of the sleeve body also decrease or increase. Electric welding sleeve according to one of claims 1 to 5, characterized in that the respective distances between two adjacent turns of the heating wire ( 12 ) from a central region of the sleeve body ( 10 ) decrease in the longitudinal direction to a front end of the sleeve body. Electric welding sleeve according to one of claims 1 to 6, characterized in that the respective winding diameter of adjacent turns of the heating wire ( 12 ) from a central region of the sleeve body ( 10 ) in the longitudinal direction to a front end ( 16 ) of the sleeve body decrease. Electrowelding sleeve according to one of claims 1 to 8, characterized in that in a sleeve body ( 10 ) laid heating wire ( 12 ) of a plurality of separate mutually independently heatable heating coils ( 12 . 12a ) consists. Electric welding sleeve according to claim 8, characterized in that a plurality of mutually independently heatable heating coil ( 12 . 12a ) in the sleeve body ( 10 ) are laid so that the turns of a first heating coil in a first axial section ( 17 ) of the sleeve body are arranged and the turns of a second heating coil in a second axially spaced apart therefrom ( 18 ) of the sleeve body are arranged. Electric welding sleeve according to claim 8, characterized in that a plurality of mutually independently heatable heating coil ( 12 . 12a ) are laid in the sleeve body so that at least one turn of a first heating coil in the longitudinal direction of the sleeve body ( 10 ) is arranged between two heating coils of a second heating coil is arranged.

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