Pipes and tubular conduits – Flexible – Corrugated
Patent
1997-12-09
1999-11-02
Brinson, Patrick
Pipes and tubular conduits
Flexible
Corrugated
138141, 138137, 264508, 264515, F16L 1100, B29C 4322
Patent
active
059751436
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a method for manufacturing a corrugated pipe and to a corrugated pipe manufactured by the method, being formed of an inner tube, a corrugated outer tube and a plastic layer therebetween.
Finnish Patents 60 825, 74 654 and 77 405, for example, teach production lines for corrugated pipe, in which plastified plastic mass is extruded with a nozzle between movable forming means pressed against one another to produce a continuous corrugated pipe. This solution provides high-quality, commercially advantageous corrugated pipe products.
To save in weight and expensive raw materials, corrugated pipe is also manufactured as double-walled pipe, so that the inner pipe consists of a conventional smooth-surfaced tube and the outer pipe of a corrugated tube formed thereon, cf. e.g. European Patent 385 465. The use of recycled plastic has been investigated in pipes manufactured in accordance with this technology so that the outer pipe has been made of recycled plastic. Thus corrugated recycled plastic can as such replace the outer tube of European Paten 385 465, or it can be employed in a foamed state to form a corrugated profile filled with foam on the inner tube.
The long-term mechanical strength of recycled plastic, which may be poor and sometimes unpredictable, constitutes the drawback of these pipes. For this reason, such tubes cannot be used in applications that require that the pipe be manufactured to design specifications of standard tubes.
Solutions are also known in which a layer of recycled plastic is disposed between a smooth inner tube and a corrugated outer tube, cf. German Offenlegungsschrift 41 28 654. This solution is attended by the drawback that in pressing the outer tube against the layer of recycled plastic to produce a bond between the layers, substantial flashes of displaced recycled plastic are formed at the web portions of the corrugations in the outer tube. These flashes have no part in the load-carrying capacity of the pipe and thus impart an unnecessary additional weight to the pipe.
Lastly, the pipe disclosed in U.S. Pat. No. 5,324,557 provides an example of `ribbed pipe` incorporating recycled plastic. In this pipe, a layer which may be of recycled plastic is provided between the outer tube comprising ribs and the inner tube. As is stated in this reference, corrugated tube differs from ribbed tube by structure and characteristics. Since the ribs in a ribbed tube are always filled, the above flash problem encountered with recycled plastic will not arise.
It is an object of the present invention to provide a method for manufacturing a corrugated pipe and a corrugated pipe manufactured by the method which avoid the above-stated drawbacks and which enable a way of employing recycled plastic in corrugated pipes which is more efficient than has previously been thought possible, and also flexible. The method of the invention is characterized in that separate layers of plastic are formed on the outer surface of the inner tube and the inner surface of the outer tube, said separate layers of plastic being affixed to one another at least at the web portions of the corrugations of the outer tube when the inner tube and outer tube are connected.
The most significant advantage of the invention is that the outer tube can be made thinner than previously, since a separate supporting layer increasing its resistance against buckling in particular is provided on the inner surface thereof. Furthermore, no unwanted flashes are produced when the inner and outer tube are brought together, but all plastic material in the pipe takes part in carrying outer or inner loads. Further advantages are afforded by the fact that by using separate layers, the layer thickness, characteristics and material can be tailored individually. This affords a considerable advantage in that by adjusting the amount and density of foam, the ring stiffness of the pipe can be easily modified without changing the joint dimensions of the pipe, such as the outer and inner diameter. Design of conventional corrugated
REFERENCES:
patent: 3550639 (1970-12-01), Okuda
patent: 3872893 (1975-03-01), Roberts
patent: 4269234 (1981-05-01), Johnson et al.
patent: 4303104 (1981-12-01), Hegler et al.
patent: 4534923 (1985-08-01), Lupke
patent: 4620569 (1986-11-01), Von Glanstatten et al.
patent: 4865797 (1989-09-01), Jarvenkyla
patent: 5324557 (1994-06-01), Lupke
patent: 5390704 (1995-02-01), Kanao
patent: 5803132 (1998-09-01), Lupke
gren Lennart
Jarvenkyla Jyri
Olsson Bjorn
Scharwachter Dieter
Brinson Patrick
Uponor B.V.
LandOfFree
Method for manufacturing a corrugated pipe, and a corrugated pip does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for manufacturing a corrugated pipe, and a corrugated pip, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for manufacturing a corrugated pipe, and a corrugated pip will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2122933