Metal working – Method of mechanical manufacture – Assembling or joining
Patent
1983-05-09
1985-01-15
Moon, Charlie T.
Metal working
Method of mechanical manufacture
Assembling or joining
29450, 29456, B23P 1102
Patent
active
044931409
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to the design of machine components, namely to flexible pipes and to methods of making same.
The inventive flexible pipe may prove most advantageous in feeding working media under conditions characterized by the effect of increased internal and external loads, e.g. in petroleum, gas, coal, and chemical branches of industry as well as in aerospace technology and in offshore hydraulic structures.
Among the above loads are primarily an axial force, gage internal or external pressure, and torque. It is important that a flexible pipe does not change its cross-section shape, preserve its flexibility under the action of such loads, and be light, simple and cheap in manufacture.
The problem of developing such flexible pipes had become urgent comparatively long time ago in aeronautics and in offshore technology. Attention is being given to this problem recently as a result of carrying out space experiments and developing the continental shelf.
Analysis of prior art technical solutions demonstrates that this problem has not been satisfactorily solved up to now.
BACKGROUND ART
Known in the art is a flexible pipe whose design makes it possible to transmit working media under increased pressure and at the same time to receive an axial tensile force (French Pat. No. 2,142,764). Said flexible pipe comprises a rubber supporting pipe onto which pipe several layers of metal braid are wound in spiral. The lowest layer and the uppermost layer are wound with a shift in the winding angles of from 6.degree. to 80.degree.. Metal wires in all the layers are subject to tension and allow the flexible pipe cross-section to be preserved at a slight bending thereof under conditions of simultaneous influence of gage internal pressure and a slight axial tensile force.
However, such a flexible pipe cannot be applied in the case of effect of distributed or local external load, e.g. under the influence of gage external pressure. Under the effect of compression in the radial direction, the cross-section of the flexible pipe loses its stability due to the fact that the metal wires constituting the braid cannot resist this effect.
Also known in the art is a flexible pipe which is intended to receive, without deformation, apart from gage internal pressure and an axial tensile force, gage external pressure (USSR Inventor's Certificate No. 668,625). In accordance with the above disclosure, this flexible pipe comprises an inner supporting pipe constructed from an elastic material onto which pipe a flat strip from a rigid material (e.g. metal) is wound. The above strip forms a cylindrical power casing with an interlayer from an elastic material being put thereupon. Two layers of shaped rods are wound in crossed directions onto said interlayer. The cross-section of each rod has a maximum size in the radial direction. Said rods are wound symmetrically at angles of up to 40.degree..
Undoubtedly, the presence of the rods wound at such angles will allow the flexible pipe to receive an axial tensile force and gage internal pressure without fracture. However, if such a flexible pipe is placed into a medium whose pressure exceeds the pressure within the flexible pipe, the deformation of the flexible pipe becomes possible even at the pressure drop of 4 to 5 kg/cm.sup.2, said deformation being accompanied by the loss in stability of its cross-section. This is due to the fact that the pressure of the external medium is freely transmitted through the gaps between the shaped rods (especially under tension) to the interlayer made from an elastic material and, correspondingly, to the power frame formed by the flat strip. The rigidity of this frame in the radial direction is low and is in no way reinforced by the shaped rods which are by themselves subject only to tension. Thus, the power frame, after having lost its stability, will be locally pressed into the flexible pipe. Simultaneously, the turns of the flat strip will separate, and the tightness of the flexible pipe will be certainly upset. Naturally, the abov
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Abdullaev Gasan M. B. O.
Aliev Gabil G.
Gadzhiev Yashar A. O.
Iljushin Alexei A.
Kasimov Dzhangir A. K. O.
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