Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Patent
1989-02-21
1991-10-01
Ball, Michael W.
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
156159, 156293, 156294, 285423, 285903, B29C 6502, F16L 4702
Patent
active
050530976
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a method of joining tubes and more particularly to a method of joining tubes having a corrugated wall of a fusible plastic material, by heat welding, the tubes at the ends to be joined terminating at a cut through a corrugation rib.
The purpose of the invention is to make possible that a homogenous and reliable joint between the tubes is provided by relatively simple working operations. Particularly, it is intended to provide for double wall tubes having a corrugated outer wall and a smooth inner wall, a joint which does not produce irregularities on the inside surface of the inner tube, which could interfere with the flow pattern in the tube.
The purpose mentioned above is achieved by the method of the invention having obtained the characterizing features of claim 1, which means that an annular body known per se, which expands when heated, is utilized in a specific manner.
The invention will be explained in more detail below, reference being made to the accompanying drawings in which
FIG. 1 is a fragmentary diagrammatic axial sectional view of the adjacent end portions of two double wall tubes to be joined,
FIG. 2 is a corresponding axial sectional view of the tubes in an initial step of the method of the invention,
FIG. 3 is a corresponding axial sectional view of the tube ends when they have been put together in order to provide an overlap joint,
FIG. 4 is a corresponding axial sectional view illustrating the welding step proper,
FIG. 5 is a corresponding axial sectional view of the completed joint between the tube ends,
FIG. 6 is a view corresponding to FIG. 3 which illustrates an abutment joint, and
FIG. 7 is a view corresponding to FIG. 3 which illustrates a joint of single wall corrugated tubes.
FIGS. 1 to 5 disclose the application of the method of the invention to double wall corrugated tubes A and B of the type having a corrugated outer wall 10 and a relatively thinner smooth inner wall 11, both walls being made of a fusible plastic material. The corrugated outer wall can be made of polyethylene while the inner smooth wall can be made of polyethylene or a fusible elastomer. The double wall tube in said latter embodiment can be bent rather easily so as to be well suited for relining of underground pipe lines. The outer and inner walls are interconnected at the corrugation grooves in a known manner and thus form closed annular cavities 12. The adjacent tube ends terminate at a cut through the corrugation ribs so that there is at each end an open annular cavity 13. In the open cavity at the end of the tube A an annular body of a type known per se is inserted, said annular body expanding when energy is supplied to it. In this case, the annular body comprises a tubular ring 14 of oval cross-sectional shape. The ring can be made e.g. of a PEX tube which has been produced with circular cross-sectional shape and then after heating has been deformed to the oval shape and has been allowed to cool in this shape. The PEX tube is wound with a heating wire (not shown) to be connected with a power source, and is coated with polyethylene on the outside surface thereof.
In the other tube B a stiffening cylindrical mandrel 15 is inserted, having chamfered end edges 16 and a circumferential inclined groove 17 in the outside surface thereof to receive therein the end portion of the thin and rather soft inner wall 11 of the tube B as shown in FIG. 2.
When the tube ends have been arranged in this manner, they are put together, the mandrel at the outer end thereof forming a ramp 18 to lift the tube A slightly when it is pushed onto the mandrel such that the outside wall of this tube will be located over the outer wall of the other tube B as will be seen in FIG. 3. The mandrel 15 is displaced axially to such position that it extends over the joint between the tubes. Then, there is also obtained an overlapping between the inner walls when the end portion of the inner wall of the tube B received in the groove is drawn off the groove at the displacement of the mandrel. An outer fixture 19 is arrang
REFERENCES:
patent: 3061503 (1962-10-01), Gould et al.
patent: 3865662 (1975-02-01), Segal
patent: 4037626 (1977-07-01), Roberts
patent: 4202568 (1980-05-01), Strom
patent: 4234781 (1980-11-01), Flink
patent: 4591193 (1986-05-01), Oltmanns et al.
patent: 4790975 (1988-12-01), Jaa et al.
patent: 4824502 (1989-04-01), Nagayoshi et al.
Johansson Ake
Johansson Thomas
Ball Michael W.
Maki Steven D.
Uponor N.V.
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