FLEXIBLE TUBE FOR HIGH-PRESSURE FLUID

摘要

PROBLEM TO BE SOLVED: To provide a flexible tube capable of safely using to transfer without penetrating molecule of fluid even though it is high-pressure fluid which exceeds 20MPa, especially, 70MPa or extra high-pressure fluid of 70MPa or more.

SOLUTION: The flexible tube is composed of a bellows tube 1 made of a metal and an tubular braided body 2 made of a metal covering outside of the tube. The bellows tube 1 is formed so that cross sectional shape of crest and trough in bellows-like tube wall is V-shaped. The braided body 2 is selected so that its both end parts are adjoined to both end parts of the bellows tube 1, respectively and the overall cross sectional area S of the braided body 2 and the metallic wire material satisfy σ×cos(θ/2)/n≫F/S, where F(N) is force with which high-pressure fluid tends to extend the bellows tube 1, S(mm2) is overall cross sectional area of metallic wire cross section emerging transverse cross section of the braided body 2, σ(MPa) is tensile strength of the metallic wire material, θ is intersected angle of 50-120 degree and n is factor of safety. Consequently, load per one crest with respect to bending of the bellows tube becomes small and thus fatigue of a metallic bellows portion is reduced.

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