DE19503888A1 - Welded pipe fitting for thermoplastic pipes - Google Patents

Abstract

A welded pipe fitting is made from thermoplastic, weldable material, as also are the two pipes themselves (20). The fitting (11) has contacts (14) for electrical power connections and between them, an spiral heating wire (15) embedded in a sleeve. The position of this coil is such that it allows the material in the contact zones to melt. A welding indicator (16) integrated with the housing of the fitting shows the condition of the welded joint. There are two contact zones for the heater. One stretches from the edge of each pipe back towards the welding indicator but not up to it, where the inner sleeve of the fitting is thin. The other zone lies under the indicator, where the sleeve is thick.

Description

The invention relates to a welding fitting in the preamble of Claim 1 specified type. Such a welding fitting can be called sweat sleeve be designed to connect two pipe parts. The welding fitting can also from a welding saddle to a tapping and / or valve matur are formed on a pipe to be provided with the valve part is connected by welding. This is what one uses in this welding fit ting arranged heating conductor, which in the case of a welding sleeve as a heating coil is designed.

The heating conductor can be either monofilament or bifilar and is in the area of the contact surfaces to be connected between the fitting Housing and the tubular part arranged. Is the heating conductor of electrical Applied to electricity, it melts through the developed Joule heat the thermoplastic material in the area of the contact surfaces. At the Schmel Due to the mass, the volume increases. Further is the heat shrinking a frozen in the fitting housing Reserve released. There is a melt pressure that the existing Fills in the area of the contact areas. After completing the The welding process solidifies the mass and connects the fitting housing inseparable from the pipe part.

The welding process is preferably carried out with an automatic welding machine advises that the required welding parameters for the various which stores fittings for different dimensions. The necessary information about the welding pair to be used in each case  the welding machine can be measured by scanning a code, e.g. B. one Obtain bar codes, which is located on the fitting housing, or by an immediate manual entry of the information. After completion the welding process, the welding data used, e.g. B. over a connected printer. Instead of or in addition for the fully automatic execution of a welding process are in the fitting housing Welding indicators integrated, which are a visual follow-up of the order enable appropriate welded connection.

In the known weld fittings in the preamble of the claim 1 specified type (DE-PS 40 18 396) consists of the welding indicator an indicator pin originally recessed in the fitting housing, that during the welding to a defined extent from the fitting housing is pushed out. It is also known (DE-PS 28 48 382), alternatively to provide a hole in the fitting housing, which if properly Melt yourself with melt mass fills. Such a hole can be oval, angular or be circular. In the known weld fittings such a melt indicator is always in that area of the pipe run from the heating conductor, where the merging contact surfaces are located. This is a considerable disadvantage.

A major disadvantage of the known weld fittings is that that the material from the pipe part in that section which is within of the fitting housing, a strong heat treatment during the Experienced welding process, whereas those are outside the fitting housing de section remains untreated. Surrendered at the transition point large temperature jumps during welding, which is why the material is on this point breaks easily under stress.

Another disadvantage is that in the area of the to be connected Contact surfaces that are tough in the final phase of the welding process liquid mass is under high pressure.

This triggers flow processes of the mass, which are also in the range of Make the sweat indicator noticeably noticeable. As stated, build the display effect of the welding indicators on such flow processes in particular towards. Due to the flow processes in the area of the welding indicator  with the known weld fittings there is a risk that the defined wire the heating conductor in the connection area changed uncontrollably. The line runs located in the area of the welding indicator shift or float. This can lead to short circuits or local overheating and incorrect welding arise at the contact surfaces to be connected. On the out as holes Welding indicators formed can lead to material breakthroughs. For this reason, it was necessary to keep the holes small, which, on the other hand, is a visually difficult to see sweat indicator justified. All this reduces the quality of the welded connection. Residual stresses in the fitting housing can accelerate these processes or reinforce.

The invention has for its object a welding fitting in the upper part handle of claim 1 to develop the type, the Bruchge move on the pipe part to be connected due to the heat treatment reduced and easily readable, sufficiently large welding indices katoren, without affecting the perfect weld connection pregnant. This is according to the invention by the in the characterizing part of the claim ches 1 listed measures achieved, the following special meaning comes to.

The invention divides the course of the heating conductor in the fitting Housing in two zones, namely a working zone on the one hand and an indicator goal zone, on the other hand, which is at different distances from each other Lich the contact surfaces to be connected. The work zone is close arranged on the contact surfaces and therefore primarily for sweat connection responsible. The heat generated in the indicator zone leads to only moderate heating of the pipe part and therefore ensures for a gradual transition between the strong material heating in the area of the work zone and the cold material outside of the fitting housing. This will make the tube part large Avoid jumps in temperature and thereby reduce the risk of breakage. The winding density of the heating conductor in the working and indicator zone could be the same if you put the heat conductor in the indicator zone in a higher level than in the work zone. The lower temperature in the transition area of the indicator zone is the larger one  Distance of the heating conductor in this zone. Additionally or alternatively, could one also the winding density of the heating conductor in the working and indicator select zone differently. A fluent is desired in the invention Transfer of heat in the end areas of the weld fitting.

Due to the different height of the cable run from the heating conductor The melting and flow processes taking place there can take place in the indicator zone does not adversely affect the connection of the contact areas in the area impact the work zone. The sweat indicators are within this Indicator zone arranged and can therefore easily suffice be large. The other design parameters ensure that the display in the area of the indicator zone provides reliable information about the quality of the welded joint in the area of the separated one Reproduces work zone.

The spatial separation of the indicator and work zone closes Lich prevents that run in the area of the indicator zone for display the melting processes adversely affect the connection of the contact surfaces impact in the work zone. There is heat in the indicator zone thrust in the edge zone of the fitting housing, which is also in a radial Shrinkage of the housing is noticeable. Such a shrinking process during welding helps to seal the fitting housing opposite the pipe part. Due to the mentioned height offset between the working and the indicator zone can cause uncontrolled flow of the material between between these zones and therefore the position of the heating conductors don't change in these areas.

Further measures and advantages of the invention result from the sub claims, the following description and the drawings. In the Drawings, the invention is shown in two embodiments. Show it:

Fig. 1 is a plan view formed on one of two as a welding sleeve for connecting tubular parts of the first embodiment of welding fittings according to the invention,

Fig. 2 in magnification and in an axial half-section along section line II-II of Fig. 1 is a side view to that shown in Fig. 1 structure,

Fig. 3 is a winding body as serving for the heat conductor used for preparing the welding sleeve of FIG. 1 with its wire guides,

Fig. 4 in enlargement a cross-sectional view through the bobbin of Fig. 3 taken along the section line IV-IV with the, in the Guide e gene inserted heating conductor

Fig. 5 shows a radial section through the heating conductor provided with the winding body of FIG. 3 taken along the section line VV,

, Partially in section along the line VI-VI of Fig. 3, the end portion of the bobbin of Fig. 5 is rich as defined in the next production phase, where the inserted heating conductor be by welding, Fig. 6 in plan view,

Fig. 7 shows the formation of the weld fittings according to the invention in a flask equipped with a valve body fitting, which is provided there, in the region of Aufschweißsattels for a pipe member further in the region of Anschweißstutzens for an end cap, and finally the region of a welding sleeve for a branch pipe 57,

Fig. 8 is a plan view of a disc-shaped insert for the saddle to the welding of the fitting of Fig. 7 with consummated heating conductors course,

Fig. 9 is an enlarged sectional detail view through the use of Fig. 8 along the section line IX-IX and

Fig. 10 shows an enlarged end view of the central section of a fully assembled unit from the use of Fig. 8 in the direction of the arrow X shown in Fig. 8.

In the embodiment of FIGS. 1 to 6, the welding fitting 10 consists of a so-called "welding sleeve", the fitting housing 11 of which is a sleeve-shaped piece made of weldable, thermoplastic plastic. The welding sleeve 10 is used to connect two Rohrtei len 20 , 20 ', through the tube space 28 , 28 ' to flow a medium. Inside the socket fitting 11 , an inner stop 13 can be provided, on which the two pipe parts 20 , 20 'introduced from the socket ends come into contact with their pipe end faces 23 , 23 '. The Verbin connection between the welding sleeve 10 with the pipe parts 20, 20 'takes place by a weld joint in the region of the already aforementioned work zone, which is designated in this welding sleeve 10 at 31 and includes a central portion from the pipe run of a continuous heat conductor 15th There, the welding processes already mentioned run between the contact surfaces 21 , 21 'of the two pipe parts 20 , 20 ' to be connected, on the one hand, and the contact surface 12 on the inner surface of the welding sleeve 10 . The particular course of the heating conductor 15 is determined by a structural unit 30 'shown in FIG. 2, to which a cylindrical insert 30 recognizable from FIG. 3 belongs. This cylindrical insert 30 produces, with its inner cylinder surface, the aforementioned inner contact surface 12 of the subsequent welding sleeve 10 .

The heating conductor 15 is electrically connected with its two ends to two provided in the end region of the welding sleeve 10 of FIG. 1 contact elements 14 elec tric. In this end region of the welding sleeve 10 there are provided as two holes 16 designed melting indicators, which extend into the region of the end sections to be described in more detail from the cylindrical insert 30 . There, the heating conductor 15 can be arranged in a special line configuration and, because of its already mentioned special function, should be referred to as an “indicator zone”, which is identified by the reference symbol 32 . In the area of the finished socket shape piece 11 , the two contact elements 14 are surrounded by molded sleeves 17 , which serve as a coupling socket for electrical supply lines, not shown. Via these supply lines, electrical current is fed to the heating conductor 15 , which already leads to the aforementioned melting processes both within the working zone 31 and in the area of the indicator zone 32 .

Due to the melting processes in the area of the indicator zone 32 , the liquid material is pressed into the holes 16 functioning as melting indicators, which collect there. The melted masses 18 , indicated by dash-dotted lines in the left hole 16 in FIG. 2, are visible on the surface of the welding sleeve 10 . The hole width is sufficiently large and can easily extend over all turns of the heating conductor 15 in the area of this indicator zone 32 .

The action of heat in the indicator zone 32 does not lead to a welding process with respect to the tube part 20 at this point, but instead exerts a moderate heat there compared to the adjacent processes in the working zone.

The actual welding processes take place in the adjacent working zone 31 . The melt masses accumulating there in the area of the heating conductor 15 are pressed into a joint 19 between the two-sided, mentioned contact surfaces 12 on the one hand and 21 , 21 'on the other hand, harden and produce, after cooling, the permanent weld connection between the three parts 10 , 20 , 20 ′.

The cylindrical insert 30 has different guides, the zones 31 , 32 ensure a different course of the heat conductor 15 in the welding sleeve 10 . In Fig. 3, this cylindrical insert 30 is still as raw, shown before the insertion of the heating conductor 15 . In the middle zone of this cylindrical insert 30 , which later forms the working zone 31 , the guides consist of a helical course of a web 33 . This web 33 , as can best be seen from the enlargement in FIG. 4, between helical turns of the web, a helical groove 34 is formed, into which, in the subsequent working stage, the heating wire 15 that can be seen in FIG. 4 can be inserted . In a further stage, as the left area of FIG. 4 illustrates, the web ends protruding above the Heizlei ter 15 according to the dash-dotted line 33 'are deformed by at least spot welding. As a result, the heating conductor 15 is fixed to the cylindrical insert 30 functioning as a winding body. The course of the turns of the heating conductor 15 together with the cylindrical insert 30 forms, when finally the contact elements 14 are mounted, a prefabricated unit 30 ', which is characterized in the area of the indicator zone 32 by a special, defined line course.

The routing of the heating wire 15 for the two indicator zones 32 is determined by the cylindrical insert 30 . The guides used for this consist in the illustrated embodiment of two mutually different elements, namely of a plurality of webs 24 extending over only a partial circle, on the one hand, which again produce grooves 25 between them, and of cams 26, on the other hand, which are free of the webs 24 left circumferential area 35 of the insert 30 are net angeord. Between the cams 26 , which are provided in groups, there is also a molded-on pin 36 in this circumferential area 35 , which is the attachment point for the contact element 14 already mentioned. The contact element 14 has a bore 22 for its mounting on the pin 36 . The contact element 14 is offset and has in its thickened lower region annular ribs 27 , between which, as can be seen in FIG. 5, the heating conductor 15 can be inserted in one turn. There is an electrical contact of the heating conductor 15 with the con tact element 14 when z. B. the upper ring rib of FIG. 7, as seen at 27 ', is deformed and the inserted heating conductor 15 is clamped.

In a first production stage, the cylindrical insert 30 is produced by injection molding and then wound with the heating conductor 15 . The heating conductor 15 can have a mutually different line course in the two zones 31 , 32 . In the area of the working zone 31 there is a spiral profile 41 of the heating conductor indicated in FIG. 6. In the middle of the insert 30 , where in the finished welding sleeve 10 of FIG. 2 the inner stop 13 comes to lie between the two pipe parts 20 , 20 'to be connected, only one turn arises due to a steeper helical pitch of the groove 34 shown in FIG. 4 of the heating conductor. A larger winding density, which is decisive for the aforementioned melting, results in the working zone 31 lying on both sides of it, which later, according to FIG. 2, has the contact surfaces 21 , 21 'intended for the welded connection. The heating conductor coil 41 surrounds the contact surface 12 of the cylindrical insert 30 on all sides.

The course of the heating conductor 15 in the area of the indicator zone 32 takes place in the illustrated embodiment in a meandering shape, the appearance of which can be seen from FIGS. 5 and 6. The meander 42 extends only over a limited angular range 45 , which can be seen in FIG. 5, which is determined by the position of the aforementioned guide elements 24 , 25 , 26 , and comprises parallel meandering legs 44 which are connected to one another by turning points 43 . The turning points 43 arise by deflecting the heating wire 15 to be laid around one of the aforementioned cams 26 . But it would also be possible to provide a spiral course of the heating conductor 15 in the area of the indicator zone 32 , which brings about the advantage of a uniform winding of the entire insert 30 .

Another peculiarity of the invention is to distance the line course in the area of the working zone 31 from the line course in the indicator zone 32 , which is done in two ways in this exemplary embodiment. As can be seen from FIG. 4, the cylindrical insert 30 has a thin wall thickness 37 in the area of the working zone 31 , which is why the heating conductor coil 41 is arranged very close to the contact surface 12 there . In contrast, a larger wall thickness 38 is provided in the area of the indicator zone 32 . The heating conductor running in this indicator zone 32 is consequently located at a greater radial distance 46 from the contact surface 12 . The different elevations of the heating conductor 15 are indicated in FIG. 4 by dash-dotted cylinder surfaces 47 , 48 . The line course 42 in the area of the indicator zone 32 thus lies at a height offset 40 with respect to the line course 41 in the area of the working zone 31 . At the transition point between the two zones 31 , 32 there is consequently a step, at whose step joint 39 , according to FIG. 5, the conductor end piece 49 of the heating conductor coil 41 comes to rest. This conductor end piece 49 closest to the indicator zone 32 is thus secured in its position by the step joint 39 .

In the present case, the indicator zone 32 is additionally arranged at an axial distance from the working zone 31 , so that a gap 29 is formed between the heating conductor coil 41 and the heating conductor meander 42 . This also prevents the aforementioned melt reaction from the indicator zone 32 to the working zone 31 . Such an axial distance 29 could, if necessary, also be used instead of the step formation 39 . Alternatively, it would also be possible to dispense with such an axial gap 29 and to separate the two courses 41 , 42 only by a radial step. Instead of a step-like transition, a ramp-like slope could also provide a gradual radial removal of the heating conductor in the indicator zone 32 . For a gradual heat transfer at the end of the fitting housing, the winding densities of the heating conductor 15 could decrease in the area of the indicator zone 32 .

After the heating conductor 15 has been wound onto the cylindrical insert 30 , it can come to the already mentioned fixing of the line courses 41 and / or 42 by pre-welding in the area of the webs 33 and 24 , which is already due to the deformed web 33 ' has been explained. Because the meandering course 42 is already adequately fixed, it is sufficient to carry out this pre-welding on the surface in the area of the working zone 31 , which takes place over the entire surface and is designated in FIG. 6 by 31 '. The cylindrical insert 30 is then provided with the contact elements 14 using the mentioned pins 36 .

For this purpose, the conductor ends which are still exposed on the meander 42 in FIG. 6 are electrically connected to the contact elements 14 in the manner already described above in connection with FIG. 5 at 27 '. There is then a prefabricated unit 30 'with its line course 41 , 42 , which is then easy to handle in the next process stage, as can be seen from FIG. 2. The unit 30 'thus produced is placed in a suitable injection mold and then the rest of the wall highlighted by hatching in Fig. 2, which is also made of weldable thermoplastic material, overmolded. To align the assembly 30 'in the injection mold, axial projections 73 on the cylindrical insert 30 are provided. When extrusion coating the Kontaktele elements 14 are fixed and around them the previously mentioned sleeves 17 sprayed around. This finally creates the socket shape piece 11 shown in FIG. 2.

In Fig. 7 to 10, the inventive construction is applied the weld fittings in a combined tapping valve fitting 50, namely three times, namely on the one hand pe at a Aufschweißsattel 51 for a to be drilled pipe part 60, a welding nozzle 52 for Abschlußkap 53 of the armature and in a welding sleeve 10 'for a further pipe part, not shown. The armature 50 is made of weldable plastic. The end cap 53 encloses the upper end piece of an inserted valve member 54 after the tube part 60 has been provided with a bore 61 beforehand via a tapping device, not shown. The welded socket 52 is provided with a metallic reinforcement 55 , which has a metallic connecting ring 56 for coupling the tapping device at the upper socket end. This connecting ring 56 also serves to fasten the valve member 54 . The welded socket 52 is designed as a T-piece, which has a branch pipe 57 . From the branch pipe 57 , a pipe part, not shown, is now ruled out, which, like the pipe parts 20 , 20 'of FIGS . 1 and 2, in turn consists of thermoplastic material. Therefore, it is advisable to design the end piece of the branch pipe 57 again as a welding sleeve 10 ', which is illustrated in FIG. 7 by the heating conductor 15 shown in broken lines'. This fitting 50 is clamped in front of the welded connection in the area of the weld-on saddle 51 on the pipe part 60 , for which purpose a counter shell 58 with clamping screws 59 are provided.

The structure of the fittings 51 , 52 , 10 'shown in FIG. 7 follows the same principles of the invention as they have already been explained with reference to the welding sleeve 10 . This is to be explained in more detail below, with reference to FIGS. 8 to 10, only for the welding saddle 51 , but also applies mutatis mutandis to the two other welding fittings 52 , 10 '.

As a carrier for the conductor course of a heating conductor 15 , an insert is also used in the welding saddle 51 , but in the present case it consists of an initially flat, annular disk 62 . This disk 62 is, similar to the cylindrical insert 30 in the welding sleeve 10 of FIG. 2, integrated by extrusion coating with plastic in the welding saddle 51 recognizable from FIG. 7, which is not shown in the hatching of FIG. 7. This applies analogously to corresponding inserts in the area of the other two weld fittings 52 , 10 'of Fig. 7. The disc 62 is designed as an annular disc and has a central opening 63 , which, in the use case of Fig. 7, the free passage allowed for the tapping device for executing the borehole 61 in the tubular part 60 . The disc. 62 serves, similar to the cylindrical insert 30 , not only as a carrier for the heating conductor 15 and for the defined line management, but also for mounting the corresponding contact elements 14 . Because of the identical structure with the cylindrical insert 30 described above, the same reference numerals as in the preceding first exemplary embodiment should be used to designate corresponding components, even if the elements have been modified compared to the first version. It is sufficient to only consider the differences, while the previous description applies in all other respects.

The inner edge 64 of the washer 62 around the central opening 63 is free. But then follows a ring strip determining the working zone 31 with the described guide webs 33 and grooves 34 , which are shown in Fig. 9, where the conductor 15 'takes a spiral course 71 a. The spiral course 71 takes place in a bifilar winding. An end cam 66 that can be seen in FIG. 8 and an adjacent guide extension 67 is used to fix the winding end there. This spiral course 71 surrounds the central opening 63 on all sides. Again separated by a gap 29 running radially in the disk, the indicator zone 32 then follows, in which the guides 24 , 25 , 26 already described are provided. The guides here consist of annular Ste Ste 24 , which provide for a meandering course 72 of the heating conductor 15 ', the turning points are determined by Umlenknocken 26 . Adjacent to the deflection cams 62 are again the pins 65 which are also formed on this disk 62 and which provide for the contact elements 14 shown in FIG. 10 to which the heating conductor end pieces are electrically connected in the manner already described. The pin 36 and thus the contact elements 14 lie diametrically opposite sides of the disc 62nd Therefore, the heating conductor meander 72 extends, as can be seen from Fig. 8, only over a little less than half the outer edge 68 of the disc, which is free in the area of the rest, in Fig. 8 right ring half of lines 15 '. In the present case, the annular gap 29 tapers towards the one end of the meander, designated 70 in FIG. 8. But that can, like insurance, for example in the preceding exporting, the work zone 31 no longer provide the defined position of the visible in FIG. 9 conductor end piece 49 into question because this fiber end piece 49 is restored to a stage shock. 39

After the heating conductor has been inserted into the disk 62 , its spiral course 71 is fixed by welding points 69 indicated by dash-dotted lines in FIG. 8, which in the present case need only run radially. Expediently, these welds 69 also extend over the indicator zone 32 and fix the meandering course 72 there . During these welding processes 69 , or even before, the disk 62 can be curved like a saddle to form the structure shown in FIG. 10. Then, as has already been mentioned, the contact elements 14 are placed on and contacted with the line ends according to FIG. 10. There is then a completely prepared construction unit 62 'according to FIG. 10.

Such a prepared assembly 62 'is now inserted again in a corresponding die, in which the metal reinforcement 55 described in conjunction with FIG. 7 is located. Then an overmolding with weldable, thermoplastic material takes place, the above-mentioned welding saddle 51 of the armature 50 being formed in the region of the curved, unit 62 'forming disc 62 . Corresponding inserts with different pipe runs in a working zone 31 and an indicator zone 34 are also used in the area of the two other fittings 52 , 10 'mentioned above. The welding indicator located in the area of the indicator zone 32 of the fitting 50 can, similar to the first exemplary embodiment, consist of a wall hole 16 . Alternatively, an indicator pen could also be used as a sweat indicator.

The alternative measures for the embodiment of the invention explained in connection with the first exemplary embodiment from FIGS. 1 to 6 can also be applied analogously to the second exemplary embodiment according to FIGS. 7 to 10. In particular, it is possible to dispense with different windings in the region of the two zones 31 , 32 and in the cases to use spiral courses for the heating conductor 15 '.

Reference list

10 welding fitting, welding sleeve
10 ′ welding fitting, welding sleeve of 57 ( Fig. 8)
11 Fitting housing, socket fitting
12 contact area of 10
13 inner stop
14 contact element
15 heating conductors
15 ' heating conductor in Fig. 8
16 wall hole, welding indicator
17 sleeve at 14
18 enamel in 16 ( Fig. 2)
19 gap between 12 and 21 or 21 ′
20 , 20 ' pipe part
21 , 21 ′ contact area of 20 or 20 ′
22 hole in 14
23 , 23 ′ end face of 20 or 20 ′
24 partially ring-shaped web at 32 , guide element
25 groove between 24 , guide element
26 deflection cams at 42 or 72 , guide element
27 ring rib at 14
27 ′ deformed position of 2 7
28 , 28 ′ tube space of 20 or 20 ′
29 axial gap between 31 , 32
30 cylindrical insert
30 ′ unit of 30
31 working zones of 30 and 62 respectively
31 ' fully welded working zone
32 indicator zone out of 30
33 footbridge in 31 , leadership
33 ′ deformed position of 33
34 helical groove between 33 , guide
35 circumferential range of 30
36 molded pins for 14
37 wall thickness from 30 to 31
38 wall thickness from 30 to 32
39 step impact between 31 , 32
40 height offset between 41 , 42
41 spiral course of 15 , line course
42 meandering course of 15 , line course
43 turning point of 42
44 meander legs from 42
45 angular range for 42 ( Fig. 7)
46 Radial distance between 42 and 12
47 cylindrical arrangement surface of 41
48 cylindrical arrangement surface of 42
49 conductor end piece at 41
50 tapping valve fitting
51 welding saddle of 50
52 welded sockets of 50
53 end cap for 52
54 valve element for 50
55 reinforcement in 52
56 connection ring for 55
57 branch pipe of 50
58 counter shell for 50
59 clamping screw between 50 , 58
60 tube part of 50
61 hole in 60
62 washer, ring-shaped insert
62 ′ unit from 62 ( Fig. 10)
63 central opening of 62
64 inner edge of 62
65 pins for 14
66 end cams for 15 ′
67 Leading Approach
68 outer edge of 62
69 welding point
70 meandering end of 72
71 spiral course of 15 '( Fig. 9, 10)
72 meandering course of 15 '( Fig. 9, 10)
73 axial projection on 30

Claims (21)

1. welding fitting ( 10 ) with a housing ( 11 ) for connecting at least one pipe part ( 20 ),
wherein both the pipe part ( 20 ) and the fitting housing ( 11 ) are made of thermoplastic, weldable material at least in the area of their contact surfaces ( 12 , 21 ) to be connected,
the fitting housing ( 11 ) has contact elements ( 14 ) for electrical supply lines and, between the contact elements ( 14 ), an electrical heating conductor ( 15 ),
the heating conductor ( 15 ) has a line course which on the one hand allows the material in the contact surface area ( 12 , 21 ) to melt and on the other hand acts via the molten material on a welding indicator ( 16 ) integrated in the fitting housing ( 11 ),
and the welding indicator ( 16 ) then indicates the correct execution of the weld connection,
characterized,
that the line course of the heating conductor ( 15 ) in the fitting housing ( 11 ) is divided into two zones ( 31 , 32 ) which are spatially separated from one another,
namely a first working zone ( 31 ) which is arranged close to the contact surfaces ( 12 , 21 ) to be connected, which, although it produces the fusion connection, does not act on the welding indicator ( 16 ),
and a second, from these contact surfaces ( 12 , 21 ) distant indicator zone ( 32 ), which is arranged in the region of the welding indicator ( 16 ). 2. Welding fitting according to claim 1, characterized in that the line course of the heating conductor ( 15 ) in the indicator zone ( 32 ) is arranged in a higher plane (48) than in the working zone ( 31 ). 3. Welding fitting according to claim 2, characterized in that a step ( 40 ) is arranged at the transition point between the indicator zone ( 32 ) and the Arbeitszo ne ( 31 ) of the heating conductor ( 15 ), the step joint ( 39 ) of the conductor end piece ( 49 ) from the heating conductor ( 15 ) in the working zone ( 31 ). 4. Welding fitting according to one of claims 1 to 3, characterized in that the line profile ( 42 ) of the heating conductor ( 15 ) in the indicator zone ( 32 ) at least in regions by a substantially unheated gap ( 29 ) from the line profile ( 41 ) is separated in the working zone ( 31 ). 5. welding fitting according to one or more of claims 1 to 4, characterized in that the heating conductor ( 15 ) extends as a continuously wound coil over the central working zone ( 31 ) and the ends side indicator zone ( 32 ) or indicator zones, but in the indicator zone or zones ( 32 ) lie in a higher plane ( 48 ) than the contact zone ( 12 ) to the tube part ( 20 ) than in the working zone ( 31 ). 6. Welding fitting according to one of claims 1 to 5, characterized in that the heating conductor ( 15 ) in the indicator zone ( 32 ) has a different line profile than in the working zone ( 31 ). 7. Welding fitting according to claim 6, characterized in that the heating conductor ( 15 ) in the indicator zone ( 32 ) has a smaller number of turns than in the working zone ( 31 ). 8. Welding fitting according to claim 6, characterized in that the course of the heating conductor ( 15 ) in the indicator zone ( 32 ) has a meandering shape ( 42 ), but the heating conductor ( 15 ) in the working zone ( 31 ) extends in a spiral shape ( 41 ) . 9. Welding fitting according to one of claims 1 to 8, characterized in that the fitting housing ( 11 ) on its the tube part ( 20 ) facing inner surface ( 12 ) has an insert ( 30 ) made of thermoplastic, weldable material and the insert ( 30 ) on the one hand carries connection points ( 36 ) for the electrical contact elements ( 14 ) and on the other hand has guides ( 24 , 25 , 26 ; 33 , 34 ) which have a defined course ( 41 , 42 ) of the heating conductor ( 15 ) both in the indicator zone ( 32 ) as well as in the work zone ( 31 ). 10. Welding fitting according to claim 9, characterized in that the insert ( 30 ) has on its outer surface facing away from the tube part ( 20 ) webs ( 33 ; 24 ), between which there are grooves ( 34 ; 25 ) and these grooves ( 34 ; 25 ) serve as guides for the heating conductor ( 15 ). 11. A welding fitting according to claim 9 or 10, characterized in that the insert ( 30 ) on its outer surface facing away from the tubular part ( 20 ) has deflection cams ( 26 ) which act as turning points ( 43 ) for the meandering course ( 42 ) of the heating conductor ( 15 ) serve. 12. Welding fitting according to one of claims 9 to 11, characterized in that the connection points for the contact elements ( 14 ) consist of molded pins ( 36 ) which protrude from the tubular part ( 20 ) facing away from the outer surface of the insert ( 30 ) and in Engage holes ( 22 ) in the attached electrical contact elements ( 14 ). 13. Welding fitting according to one of claims 9 to 12, characterized in that the insert ( 30 ; 62 ) together with the in its guides gene ( 33 , 34 ; 24 , 25 , 26 ) inserted heat conductor a prefabricated unit ( 30 ', 62 ') forms and the guides hold the inserted heating conductor at least by point-wise welding ( 31 '; 69 ) ( Fig. 7, 9). 14. Welding fitting according to one of claims 1 to 13, characterized in that the welding fitting is a welding sleeve ( 10 ) which serves to connect two pipe parts ( 20 , 20 ') ( Fig. 2). 15. welding fitting according to claim 13 or 14, characterized in that the heating conductor ( 15 ) in the indicator zone ( 32 ) relative to its position in the working zone ( 31 ) is set radially higher ( 40 ) ( Fig. 4). 16. Welding fitting according to claim 13, 14 or 15, characterized in that the insert ( 30 ) of the welding sleeve ( 10 ) is cylindrical and in the central working zone ( 31 ) as a winding body for a helical course ( 41 ) of the heating conductor ( 15 ) serves, but the heating conductor ( 15 ) in the two end indicator zones ( 32 ) has a meandering course ( 42 ) with partially cylindrical meandering legs ( 44 ). 17. Welding fitting according to one of claims 1 to 16, characterized in that the welding fitting belongs to a tapping fitting ( 50 ) and / or a valve fitting which has a welding saddle ( 51 ) for the tubular part ( 60 ) and / or a welded socket ( 52 ) for an end cap ( 52 ) and / or a welding sleeve ( 10 ') for a pipe branch on the fitting ( 50 ), where a heating conductor ( 15 ') and a welding indicator are arranged, ( Fig. 8, 9). 18. Welding fitting according to claim 12 and 17, characterized in that the use of the Aufschweißsaddels ( 51 ) consists of a curved disc ( 62 ) in which the working zone ( 31 ) the central loading area of the washer leading to one of the quotes ( 52 ) opening (63), while the indicator zone (32) is arranged in the edge region of the disc (62) where the heating conductor (15 ') opposite the welded effective contact surface of the disc (62) in the indicator zone (32) in a higher plane is than in the work zone. 19. Welding fitting according to claim 18, characterized in that the heating conductor ( 15 ') in the working zone ( 31 ) has a spiral course ( 71 ), but runs back and forth in a meandering manner in the indicator zone ( 32 ). 20. Welding fitting according to claim 18 or 19, characterized in that the meandering course ( 72 ) of the heating conductor ( 15 ') in the indicator zone ( 32 ) of the disc ( 62 ) is substantially semicircular on one side of the in the disc ( 62 ) recessed opening ( 63 ) extends ( Fig. 9). 21 welding fitting according to one or more of claims 1 to 20, characterized in that the as a hole ( 16 ) in the fitting housing ( 11 ) or as in the fitting housing ( 11 ) lowered indicator pin trained welding indicator on the heat conductor ( 15 ) or ( 15 ') formed indicator zone ( 32 ) is arranged.