DE10009475A1 - Thermoplastic pipe connector uses intermediate layer as strip of expanded metal lattice material with outer and inner layers joined by thermoplastics threaded through lattice mesh. - Google Patents

Abstract

The intermediate layer is comprised of belt or mat type perforated and twisted lattice material bent out of its center plane and specifically composed of expanded metal or convertible material. The outer layer extends over the intermediate layer with its inner layer, being joined to this through the mesh apertures to give a firm plastic connection. Two thermoplastics plastics thread through the lattice apertures as well as outer and inner layers so as to tooth these together and in this way both reinforce the intermediate layer and complete a heating element. The connector comprises two plastic layers concentric to the main axis to enclose the hyperboloid double cone of lattice material (3) as inner cone (23) of axi-parallel inside layer (4) and two mirror-symmetric ends (5) going into an opening (6). Two conductive contacts (7) linked by conductor strap (8) are positively joined to the lattice material (3).

Description

The invention relates to a grid-like armored Pipe connector for thermoplastic pipes made by extrusion produced at least one thermoplastic, with the same lattice-like carcass reinforced and not detachable on one or both sides with at least one pipe section is connected and at the same time represents a welding sleeve.

Pipe connectors are all here in pipeline construction used elements such as pipe pieces, fittings and valves stood, the cylindrical and to be connected by sleeves the exhibit and essentially from thermoplastic art substances such as PVDE, PFA, PPS, PE, PB, PP, FEP, PVC.

An important publication on the state of the art is the "Plastic Pipe Manual: Pipe Systems for Supply and Disposal and Other Areas of Application", 3rd edition, Vulkan-Verlag Essen ( 1997 ).

Rigid pipes belong to the further state of the art thermoplastics that are used for the flow Mung transport of flowable media is already beneficial have shafts. They are characterized by good dimensional stability, Stability, corrosion resistance and long stability or durability. In particular, polyolefins such as Po compared to polyethylene and polypropylene or similar copolymers aggressive chemicals such as acids, bases, most organic solvents or abrasive mixtures of minera solid particles with liquids highly resistant.  

Some further developments led to composite Ver plastic pipes with individual, concentric to the pipe axis running shifts. Embedded grid-like intermediate layers take on tasks such as mechanical reinforcement and haf outer wear layers and inner layers, the ge stable against an attack of the media to be transported are. For the connection of alien plastic layers, at for example of polyolefins and polyfluorinated olefins no effective chemical adhesion promoters known to date. Usual che connections are based on shrinking techniques (DE 40 24 997) or on sandwich-like construction methods (DE 33 22 378, EP 0 836 042) to the strength against external forces increase or damage, detachment or destruction of individual layers. Reinforcements with an inert company In this way, substances allow adhesion to one another zender layers (EP 0 358 178, DE 43 22 659). Here there is but there is a risk of delamination because it adheres to fibers Plastics slide away from each other when under load separate. In DE 42 38 696 two pipe layers are advantageous clinging like a meandering clinging without an adhesion promoter interlocked that the upper layer can be replaced if necessary can. Plastic pipes with alien thin Me are also known waist pads, the wrap-like bands at the edges to Solidify the intermediate layer overlap (DE 23 52 086). Opp if necessary, metal foils are provided with perforations that a mutual penetration while solidifying the Allow interconnecting plastics (EP 0 567 667). Inside pipes and outer jackets, between which are used to shield electrical fields metal foils must at least ver be glued (DE 30 23 214, DE 32 09 600). However, a be peacefully high strength with large pipe diameters on this Can never be achieved.  

Compared to detachable pipe connections, the pipe sections with are connected by flanging and screwing already detachable, compressible sleeve or sleeve connections Significant manufacturing advantages with a lower Expenditure on individual parts. It is a form and forceful union of pipe shots forced themselves in the case of reinforced pipes, not only on the thermoplastic layer with a high degree of longitudinal and lateral stability, but also on the carcasses of the individual pipe sections.

In the case of non-rigid pipes, the must also be wide-meshed carcass made of spirally wound rings of a ge know flexibility is enough that when lowering the internal pressure a collapse of the corrugated pipe or hose structure ver hinders (DE 33 44 544, DE 34 01 931, DE 38 40 584, DE 44 32 481). The permanent connection is made by means of the outside attached, thermoplastic deforming dies, which at consist for example of pressing jaws or tongs and axial and Allow radial pressing or just squeezing, press however, connections do not yet guarantee a sufficiently high level Tensile strenght. It was also not yet known that parts mesh individual carcasses by pressing.

Partial melting also belongs to the prior art and welding of thermoplastics with the help of externally electrically operated welding sleeves or so-called Weld fittings, each with a sleeve or socket on the raw rende verse as a plug-in part (cf. DE 196 11 883, DE 195 47 507) hen, or that. Pressing pipes from a plastic Metal composite (DE 197 04 824, DE 197 35 919), at least the best hend from a pipe connector, a compression sleeve and a sealing tend support part. The heating elements in the form of resistance wires are covered with a thermoplastic material or embedded only in plastic. By supplying electrical  Energy becomes a Joulsche sufficient to connect the parts Released heat, the frozen shrink reserves from the Melt solidified plastic parts. The relatively big one Expansion coefficient of the plastics enables a high Penetration of different, also foreign materials. The Welding fittings should preferably be injection molded parts. Your fro position is preferably carried out by blow or suction molds, extrusi ons or coextrusion molding or sequential blow molding. It thermoplastic plastics such as poly are preferred olefins (TPE-O, TPE-V), polyamides (TPE-A), polyester (TPE-E) and Styrene (TPE-S) used. The sleeves and / or the insert parts are equipped with stops for preliminary fitting and fixation see to compensate for axial or radial play. You own usually welding indicators in the form of in the melting zone introduced recesses or openings for the purpose of optical con trolls for the exit of the melt, which the execution of an ord display the welded joint in accordance with the and reduce bubble-free inner surfaces. Both together of the surfaces to be connected, that of the fitting and the insert les made of plastic, are necessary for a successful welding contact to be in close contact. This sets relatively tight dimensional tolerances ahead of increased manufacturing costs. High heating outputs in The area of the weld is achieved in that the Kar cash register overlapping. It is caused by thermal expansion a predominantly radially directed sweat pressure, whereby manufacturing tolerances between the sleeve and pipe be equalized and the carcass is penetrated. It exists however, especially with large diameters, the risk that the The welded joint breaks due to the tensile load. As before, be knew, on the other hand, no precautionary measures were taken at for example by mechanical pressing under the same lead plastic deformation.  

It is also known that heating elements of welding sockets kon can be supplied tactlessly by eddy current. In the However, DE 42 14 279 do not yet serve the heating elements as reinforcement.

Plastic pipes with a high internal pressure cannot do without a reinforcing, stable carcass absorbs radial loads as well as those caused by internal pressure withstands gentle axial tensile loads. Extreme axial pressure loads are appropriately absorbed by longitudinal reinforcements, which is a rod or rod running parallel to the pipe axis have shape. The associated cross reinforcements serve to To manufacture pipes, the strength and stability of which by me metallic structure of the carcass determined in the form of latticework becomes. This is how pipes are made from longitudinal and welded pipes Cross reinforcements penetrated by the thermoplastic gene, mesh-like cells of the carcass (SU 92 99 51, SU 13 66 757). It is also known that structure forming lattice-like molding materials, such as expanded metals, excellent suitable for reinforcing inserts in thermoplastic materials. Due to profiled deflections of the rows of slots or grids from a medium level of material they resist Bie and winding processes. In DE 23 54 731 the defor mable meshes of re-forming of the layers by shrinking fen, for example from PTFE to the finished tube body using Sin tern. Structurally stable expanded metals show the flat Deformation by directional rolling or rolling preferred directions on, parallel to a diagonal of their diamond-like, openings forming structured cells. Also be preferred edges are conducive to deformation, with unequal mate rial cross sections or widths of the webs between the openings available and at different angles of two preferred directions are oriented. Nevertheless, the webs are of larger cross-sectional dimensions  always in the direction of primarily directed force effects arranged.

The applicant has already proposed longitudinal reinforcement on the circumference of a rigid cylindrical welding electrode to arrange. An armature made of expanded metal becomes spiral wound up and welded by means of a roller mechanism. At the same time extruding plastic material into one Mold cavity fed to a compact tool. The goal is there the increase in production output, expressed as one each Unit of time manufactured tube length. Thus, the diameter of the Pipes in compliance with the strength criteria for required dimensions wide and improved parameters of quality and performance increase. The common manufacture is also advantageous the outer, inner and intermediate layer of the tube in one single, unified device with limited space.

So far it has not become known that the carcass even as a heating element for the welding of socket and on plug-in parts can be used, the fusion within the This takes place and mechanical loads jointly from the carcass se and the solidified melting material and no additional Liche sealing elements are required.

The invention has for its object to develop a tube connector provided with profi carcass, which is also a welding sleeve and

• - high resistance to tensile and compressive loads stungen in the longitudinal direction, but also in diagonal or transverse direction lines, with low expenditure of plastic material,
• - an improved connection between different ther plastic materials allowed and axial as well as radial Force components based on preferred directions catches,  
• - An advantageous combination of fewer items by Ver pressing and welding offers and
• - in which the carcass itself serves as a heating element.

This object is achieved by the in the claims and the associated drawings pipe connector solved.

According to the invention, a strip or band-like shape is formed designed, profiled lattice molding material wrap-shaped as armie tion, alternatively applied to a base body and to the touching edges firmly connected. The molding material is coming pulls an expanded metal. It is not necessary that the wel len-shaped or serrated edge cut edges in shape grasp closed ridges and join them together.

The band thus comprises a larger number of cells already predetermined by the lattice molding material according to the selected bandwidth and the specified strength value about 8 to 15 cells each in the transverse direction. The git terformstoff has regularly arranged openings, the ma depict cells with limited, regularly structured cells len. These openings are in turn limited by webs that either lie in a common material plane or preferred are formed out of this plane at an acute angle. If the individual bridges are considered as a group together and in oriented in the same direction at an angle, so they are as oblique, tooth or scale-like deflections to the material level of the lattice molding material in the outside layer at a positive acute angle and inside layer beneath the same, but centrally symmetrical to it mirrored, negative angles directed. Wrapped tapes can with their openings and the deflections of their webs in one Direction of the winding. With this arrangement a deformation along the longer diagonal of an opening.  

The individual webs are, in their group-like lattice Ver run following, both at a set angle of inclination as also grouped at a pitch angle of the pipe axis. Also these are preferably acute angles. Deviatingly takes one this angle almost the value 0 ° and the other accordingly almost the value 90 °, so a group of webs is approximately along the Pipe axis, the other group along the pipe circumference and approximately across aligned with the pipe axis. Both groups of bars can ver different material cross-sections and therefore different strengths properties that they have in different orias have pipe axis axis.

The molded lattice material can optionally also consist of a Are made of plastic that is sufficiently hard and also to at least partially with the thermoplastic outer and inner layer can connect. Here it is advantageous to use a mat mat rial to use a mixed molding material that is in shape a point-connected fabric made of a plastic and egg metal can occur.

A particular inventive idea is that a Injection molding is applied and the scale-like out Steering of the webs of the lattice molding material with the art interlocking and interlocking material. While a single or two different from each other, forming the layers of the pipe plastic in a shared mold space with the carcass running in the middle of it The plastics are partly in the dough-like thermoplastic Condition the openings between the webs. Both layers ver bind at least partially with mixing and ab bond with each other and solidify between the webs as in egg ner positive form of the composite material, so that the plastic as Image shows a negative form of the webs.  

In this way, the profiled lattice shape is created Reinforced tubular plastic layers of the pipe joint those who not only have a positive connection with each other, but also establish a frictional connection. The deflections of the Ste ge preferred to be oriented in the directions that above all Resistance to a tensile or compressive load, but also train against stress caused by twisting. Are in Expanded molding webs of different cross-sections see that are grouped in one direction will be grouped wise webs of the larger cross-section against external force effects a more stable behavior than those smaller cross Have cut and so be oriented in a preferred direction can better counteract the causal stress is counteracted.

With a grouped alignment of thicker bars under the angle of inclination of almost 0 ° and weaker bars below the In this way, pitch angles of almost 90 ° can be used for the Pipe withstand greater pressure and tensile loads in the longitudinal direction will be. Preferred applications of the pipe connector result so as drill pipes in which the internal pressure to be intercepted un can be subordinate. If the thicker bars at an angle of almost 90 ° and ent speaking weaker bridges at the pitch angle of almost On the other hand, the pipe can also hold more extensive internal pressure recordings. This results in better application options for high pressure pipes that are used for the pressure promotion of them flowing media are used and the axial forces under are ordered. One-sided sloping bridges take prefers torsional forces in a direction of rotation caused by the Interaction of the axial and radial forces as with drill pipes arise. If external loads only in one direction occur, it can be advantageous to mat-like and combi Use molded plastic and metal materials. Here  the metallic webs are primarily in the direction of the largest Be stress-oriented.

This is the process for manufacturing the pipe connector characterized that in a common device in one first step a longitudinal reinforcement on an alternative tubular shaped body applied and in a second step a transverse reinforcement made of the lattice molding material is wound up helically is celt. Then the connection is made at the touch put both reinforcements to the carcass, preferably by Rol lenwelding. Not only the longitudinal reinforcements are included connected to the cross reinforcement, but also weld it touching and interlocking edge points of the stretch molding material. Then, at almost the same time, the mold cavity is opened a known injection molding tool at least one ther introduced plastic. The mold cavity is like this designed that at least one plastic portion between the outside layer and intermediate layer above this, and a second type part of it separated below the intermediate layer, the inside forming layer, the tool is fed. The pro rata Streams of plastics are made up of proportional throughputs and one common supply pressure controlled so that an approx herte equal distribution of both parts in the mold cavity and in the Openings of the intermediate layer.

The invention is explained in more detail using examples. Self ver Of course, the invention is not only based on these examples limits.

In the accompanying figures:

Fig. 1: the pipe connector, with the insertion of a so to connecting pipe section, shown on a common main axis

Fig. 2: Two preformed strips of material made of lattice material with diamond-shaped mesh openings of the reinforcement, lying one above the other in a perfect fit; in supervision and in section,

. FIG. 3: Two strips of material according to Fig 2, but within range of the egg nes moderate tolerance mesh arrangement offset to one another, in an imperfect fit,

Fig. 4: Two strips of material according to Figure 3, in imperfectly fitted fit and under tolerance cone angles. on average,

Fig. 5: A modification of the pipe connector and the Rohrschus ses according to Fig. 1; on average,

Fig. 6: Consecutive stages of manufacture of the pipe joint to the pipe section,

Fig. 7: Another modification of the pipe connector, designed as a reducer.

example 1

With reference to FIG. 1, the pipe connector 1 consists of two plastic layers 2 arranged concentrically to the main axis; 2 ', between which the lattice molding material 3 is located in the form of a hollow and hyperboloid-shaped double cone. The pipe connector 1 has two mutually mirror-symmetrically arranged, terminal insertion ends 5 , each of which merges into the two recesses 6 . The angles of the recesses 6 with respect to the main axis are larger than the corresponding angles of the inner cones 23 to the latter. Two contacts 7 are each connected to an associated guide band 8 and are in a positive connection with the molded lattice material 3 . Two control openings 9 are located at a distance of approximately one third to half of the inner cones 23 , measured from the insertion points 5 . The plastic layer 2 'has an axially parallel section 4 , which is delimited by the two seats 11 . Portions of the lattice molding material 3 with the plastic layer 2 are arranged in the recesses 6 at a distance such that a further open inner cone is formed. The lattice molding material 3 of the pipe connector 1 in the inner cone 23 is largely freed from the plastic layer 2 '.

The pipe section 20 also consists of the two plastic layers th 2 ; 2 ', between which the lattice molding material 3 ' is located. The pipe section 20 has a tip end 21 which merges with a chamfer 22 in the plastic layer 2 and with a gate 25 in the Git terformstoff 3 'with the plastic layer 2 '. It has an inner cone 23 'and an outer cone 24 . The pipe section 20 is limited by the stop 26 . In the gate 25 portions of the lattice molding material 3 'with the plastic layer 2 ' are partially arranged at such a distance that a further, steeper outer cone is formed.

In the same way, the plastic layer 2 on the outer cone 24 is largely removed from the lattice molding material 3 'of the pipe section 20 . The lattice moldings 3 ; 3 'are, in each case accordingly, by the webs 40 ; 40 'and the stitches 41 ; 41 'characterized. The pipe connector 1 has a mark 12 , the pipe section 20 has a mark 12 '. The outer diameter of the pipe connector 1 exceeds the outer diameter of the pipe section 20 in the form of the muf fe formed. The lattice moldings 3 ; 3 'consist of an expanded metal of the quality of a low-carbon unalloyed steel. The contacts 7 are made of copper and the conductive strips 8 are made of a copper foil.

In a first step, with reference to FIG. 1, the pipe connector 1 with an inner cone 23 and a seat 11 and the pipe section 20 with the inner cone 23 'and the stop 26 are joined together by axial pressing, so that the stop 26 abuts the chamfer 22 . The larger diameter of the inner cone 23 inside half of the pipe section 20 largely resembles the diameter of the section 4 within the pipe connector 1 . The lattice moldings 3 ; 3 ′ touch at least partially on the lower edges of the webs 40 in the area of the outer cone 24 . They also touch at least partially in the gate 25 with the end upper edges of the webs 40 '. The stitches 41 ; 41 'are already largely on top of each other and overlap.

The brands 12 ; 12 'are directed towards each other according to FIG. 2 at a common point and ensure the overlap of the lattice molding materials 3 ; 3 'by the webs 40 ; 40 'while maintaining the congruence of the stitches 41 ; 41 'nestle together. A preliminary press fit between pipe connector 1 and pipe section 20 is generated.

In a second step, the welding current is supplied via the two contacts 7 , the two guide strips 8 and the lattice molding materials 3 which are conductively connected to one another; 3 'by the plastic layers 2 ; 2 'are largely exempt. The melting process fills the columns 27 ; 27 'between the seat 11 and the stop 26 and between the chamfer 22 and the gate 25 . In the course of the melting process, the preliminary press fit changes into a seat in which the webs 40 ; 40 'mesh with each other and the stitches 41 ; 41 'lying on top of one another. The solidified melt of the plastic welds the press fit between pipe connector 1 and pipe section 20 . The plastic layers 2 ; 2 'penetrate each other and are within half of the webs 40 ; 40 'embedded so that the delimitation of the layer area of the mixing zone predominantly within the webs 40 ; 40 'runs.

Example 2

With reference to FIG. 3, tolerances in the overlapping equality of the stretch-form materials 3 ; 3 'approved. The brands 12 ; 12 'do not face each other and are directed laterally past a point. The webs 40 ; 40 'do not mesh completely. As a result, the stitches 41 overlap; 41 'also not completely. Since the webs 40 ; 40 'still touch and partially interlock with each other, there is an even more positive connection between the pipe connector 1 and the pipe section 20 .

Example 3

With reference to FIG. 4, tolerances in the angle of attack of the inner cone 23 and the outer cone 24 are permitted. By an additional radial compression during the welding operation, according to Figure 5 is a complete covering of the mesh. 41; 41 'can be achieved.

Example 4

Referring to Fig. 6 consist pipe connector 1 and the pipe 20 ren shot from similar reinforced with the grille molding material 3 Roh. The similarly oriented grid molding material 3 is located on the same circumferential plane of the pipe joint. The outer diameter of the pipe connector 1 is the outer diameter of the pipe section 20 according to Fig. 6a and does not exceed this, as shown in Fig. 1, in the form of a sleeve. There are also no contacts 7 or guide strips 8 . According to Fig. 6b, the pipe connector 1, the shank 5 and the Ausneh mung 6 enucleated and the outer cone 23 peeled off. On the tube shot 20 , the plastic layer 2 is removed in a corresponding manner at the tip end 21 . A chamfer 22 and a gate 25 are formed. According to Fig. 6c of the pipe connector 1 is expanded, the inner cone 23 is formed. The pipe section 20 is stretched before, whereby an outer cone 24 is formed.

Pipe connector 1 and pipe section 20 are axially pressed. The welding takes place by means of eddy current, which is generated within the grit molding material 3 by means of a circumferentially applied tool (not shown). After pressing and welding, a pipe connection is formed according to FIG. 6d, the gaps 27 ; 27 'are filled with solidified melt.

This type of pipe connection of pipe connector 1 and pipe section 20 is advantageous where pipe bushings are to be made by openings that have approximately the same or a slightly larger diameter than the pipe connection.

Example 5

Referring to Fig. 7, the reducer has an insertion end 5 of larger diameter and a tip end 21 of smaller diameter. The lattice molding material 3 is stretched in the direction from the insertion end 5 to the tip end 21 in such a way that the original major and minor diagonals of the diamond-shaped stitches 41 merge into shortened main diagonals and elongated minor diagonals of the diamond-shaped stitches 41 '. The size and shape of the stitches 41 and 41 'correspond to those stitches formed by two tube sections 20 ; 20 'of different diameters are formed.

The pipe connector is used wherever liquid or gases in pipes, especially those with a large inner diameter be transported under high pressure and a large solidification supply of the pipe connector with individual pipe sections, but also egg ne great external strength of a pipe system with high mechani shear load, with reduced use of materials and a high host Manufacturing efficiency must be achieved.

Preferred areas of application concern pressure lines in the Water and wastewater technology, for hydraulic engineering installations, in power plant technology and in the chemical industry, here preferred for the liquid transport of aggressive media as well as high-strength pipe connectors for conveying and flushing purposes. That concerns u. a. Drilling pipes for bringing down in moderately firm layers of earth and rock,  in deep well construction and drilling, at the extraction of fossil fuels or when founding buildings. The Pipe connector also allows the connection of rod-shaped hollow bodies with a high length-to-diameter ratio, as for high fe poles, hollow masts, piles or special strengths demanding insulation of tubular electrical and / or electro magnetic conductor.  

Reference list

1

Pipe connector

2

Plastic layer

2

'' Plastic layer

3rd

Lattice molding material

3rd

'' Lattice molding material

4

section

5

Insertable

6

Recess

7

Contact

8th

Guideline

9

Inspection opening

11

Seat

12th

brand

12th

'Brand

20th

Pipe shot

20th

'Pipe shot

21

Spiked

22

chamfer

23

Inner cone

23

'' Inner cone

24th

Outer cone

25th

Bleed

26

attack

27

gap

27

'Gap

40

web

40

'Footbridge

41

mesh

41

'Stitch
α angle of inclination
β pitch angle
γ cone angle

Claims (6)

1. Pipe connector for thermoplastic pipes, which is armored with the aid of a profi lised carcass and consists of an outer wall layer of a thermoplastic and a same or different inner wall layer formed from thermoplastic and from at least one intermediate layer forming the carcass, with a positive fit such as there is also a force circuit between the individual layers, and which is at least molded onto a prepared pipe section, characterized in that the intermediate layer consists of at least one strip of a band-shaped, mat-like, deflected from a central material plane, perforated and coiled lattice material consists of a stretch-form material or preferably of an expanded metal, the outer layer extends with at least one inner layer over the intermediate layer and also with this via mesh-like openings in a solid and plastic connection eht, with at least one and predominantly two thermoplastics penetrating the openings of the molding material and the outer and inner layers at least partially and mutually interpenetrating and interlocking within the openings and interlocking and the intermediate layer is simultaneously reinforcement and heating element. 2. Pipe connector according to claim 1, characterized in that the pipe connector ( 1 ) consists of two concentrically arranged to the main axis th plastic layers ( 2 ; 2 '), between which there is in the form of a hollow and hyperboloid-shaped double cone of the grid molding material ( 3 ), forming an inner cone ( 23 ), which has an axially parallel inner section ( 4 ) with two seats ( 11 ) and two terminal insertion ends ( 5 ) arranged in mirror symmetry with each other, each of which merges into the two recesses ( 6 ), two electrically conductive contacts ( 7 ) are each connected to an associated guide band ( 8 ) and are in positive connection with the grating molding material ( 3 ) and two control openings ( 9 ) are provided, a pipe section ( 20 ) likewise consisting of the two plastic layers ( 2 ; 2 ') exists between which the lattice molding material ( 3 ') is located and which has at least one tip end ( 21 ) with a chamfer ( 22 ) in the plast s layer ( 2 ) and with a cut ( 25 ) into the lattice molding material ( 3 ') with the plastic layer ( 2 ') and which has an inner cone ( 23 ') and an outer cone ( 24 ) and is delimited by the stop ( 26 ) , and the lattice molding materials ( 3 ; 3 ') characterized by the webs ( 40 ; 40 ') and the mesh ( 41 ; 41 ') and these two opposite brands ( 12 ; 12 ') are assigned, the outside diameter of the pipe connector ( 1 ) being the outside diameter of the pipe section ( 20 ) in the form of the sleeve formed and the gap ( 27 ) between the chamfer ( 22 ) and the recess ( 6 ) and the gap ( 27 ') between the section ( 4 ) on the seat ( 11 ) and the stop ( 26 ) are connected. 3. Modified pipe connector according to claim 1 and 2, characterized in that the outer diameter of the pipe connector ( 1 ) has the same diameter as the pipe section ( 20 ). 4. Modified pipe connector according to claim 1 and 2, characterized in that the insertion end ( 5 ) has a larger diameter and the tip end ( 21 ) has a smaller diameter and the lattice molding material ( 3 ) in the direction from the insertion end ( 5 ) to the tip end ( 21st ) is so stretched that the main and secondary diagonals of the diamond-shaped meshes ( 41 ) merge into shortened main diagonals and elongated secondary diagonals of the diamond-shaped meshes ( 41 ') and the size and shape of the meshes ( 41 ; 41 ') change to those Correspond to stitches that are formed by two pipe sections ( 20 ; 20 ') of different diameters. 5. Pipe connector according to claim 1 to 4, characterized in that the pipe connector ( 1 ) with one or two pipe sections ( 20 ) is pressed and welded. 6. Pipe connector according to claim 2 to 4, characterized in that the welding takes place by means of eddy current.