Stock material or miscellaneous articles – Structurally defined web or sheet – Including aperture
Patent
1995-06-12
1997-10-07
Watkins, William
Stock material or miscellaneous articles
Structurally defined web or sheet
Including aperture
428139, 428156, 428 99, 219544, 285 211, 285 212, 285292, 29611, 29619, 26427211, 26427218, 26427919, F16L 4700
Patent
active
056745885
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a welding sleeve comprising a plastic molded piece having a heating element and an improved plug contact for connecting a source of current to the heating element.
A plastic molded piece of the aforementioned type which is formed as a welding sleeve is known, for instance, from Federal Republic of Germany 28 23 455 C3, in which the plug contact is formed directly by the resistance wire of the heating element, the wire being arranged in the form of a loop over an arm which is arranged within a recess.
The foregoing welding sleeve has the disadvantage that the resistance wire is not fastened, so that a dependable plug connection to the source of current is not assured and a plastic-covered resistance wire must first of all have the insulation removed from its end as plug contact before formation of the loop.
It is the principle object of the present invention to provide a welding sleeve comprising a molded piece of the aforementioned type, which permits an automated production of plug connections for the heating element even when an insulated resistance wire is used, in which connection the plug connection must assure a dependable connection to a source of current.
SUMMARY OF THE INVENTION
In accordance with the invention, the foregoing object is achieved by providing a welding sleeve having an improved plug contact for assuring a good connection between the source of current and the heating wire of the welding sleeve.
The process of the invention makes simple automated production of a plug connection possible in the case of molded pieces having heating elements, which process can be used both with bare resistance wires and with plastic-covered resistance wires.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is shown, by way of example, in the accompanying drawings and will be described below. In the drawings:
FIG. 1 shows half of a welding sleeve, in part in longitudinal section;
FIG. 2 is an enlarged view of the portion having the plug connection of FIG. 1;
FIG. 3 is a section along the line III--III of FIG. 1;
FIG. 4 is a section along the line IV--IV of FIG. 3 before the coating of the winding support; and
FIG. 5 is an enlarged view of a part of FIG. 4.
DETAILED DESCRIPTION
FIG. 1 shows a molded piece, developed as welding sleeve 1, for connecting tubular parts of thermoplastic material. A sleeve body 2 consists of an inner sleeve part 3 developed as winding support and of an outer sleeve part 4. A heating element 5 which consists of a resistance wire 6 embedded in the inner sleeve part 3 or inserted in turns in grooves 7 is arranged on the inner sleeve part 3.
Plug connections 8 for the feeding of the current are arranged on the two ends of the resistance wire 6.
FIGS. 2 to 5 show a plug connection on a larger scale. For this purpose, retaining elements 10 are integrated in or formed on the ends of the winding support 3.
The retaining element 10 has a recess 11 which is preferably developed with square cross section and is surrounded by a side wall 12 which is correspondingly square. A projection 13 is arranged within the recess 11 and has side surfaces 13' which define with side wall 12 slots 24.
The two opposite walls 12a, 12b of retaining elements 10 are openings provided with opening 14 which extend transverse to the longitudinal axis 9 of the welding sleeve. The corresponding end of the resistance wire 6 is inserted into the slits 14 upon the winding onto the winding support 3 and thereby comes to rest on the projection 13.
A plug contact 15 which can be inserted into the recess 11 of the retaining element 10 and is produced by shaping from a metal sheet has an insertion part 16 and a connection part 17. The connection part 17 is developed either as a flat plug or, preferably, as a round plug, the sheet metal being shaped into a tubular part in the case of the second embodiment. The insertion part 16 is shaped from the sheet metal either in U-shape or, as can be noted from FIG. 2 and FIG. 3, in rectangular shape, and has oppose
REFERENCES:
patent: 4224505 (1980-09-01), Sturm
patent: 5088933 (1992-02-01), Ribbeck
patent: 5163713 (1992-11-01), Brettell et al.
patent: 5228186 (1993-07-01), Brettell et al.
patent: 5252810 (1993-10-01), Trosch et al.
Petry Dirk Alexander
Porfido Erasmo
Georg Fischer Rohrleitungssysteme AG
Watkins William
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