METHOD FOR MAKING TUBES OF FIBROUS COMPOSITE MATERIALS WITH LENGTHWISE REINFORCEMENT Russian patent published in 2000 - IPC

FIELD: plastic working of fibrous composite materials, possibly in aerospace industry branch and other industry branches. SUBSTANCE: method comprises steps of making reinforced tubes at assembling blank directly on mandrel; rigidly securing blank to mandrel and drawing them together through drawing die at isothermic conditions by one pass; before drawing shielding blank in addition by means of technological envelope; using drawing die whose working surface has two zones with length values selected according to expression : L1=12.3-0.67α-0.198h, where α - conicity angle of drawing die, h - thickness of technological envelope; selecting length of second zone L2 according to expression: Lmin <L2 <Lmax and Lmin = tV, where t- time period of adhesion interaction; Lmax = σ_cS_c/μP_cp2πR′, where σ_c - temporary resistance of fibrous composite material to tension, S_c - area of cross section of technological envelope, μ - friction factor, p_cp - mean stress on surface of fibrous composite material, R - outer radius of technological envelope. Second zone of drawing die has lengthwise cavities. EFFECT: elimination of yielding of surface layers of fibrous composite materials in cavity of second zone of drawing die, possibility for maintaining integrity of fibres, manufacture of materials with compact structure having high-quality surface. 1 dwg, 2 tbl, 2 ex