Weldless aluminum alloy lining neck-spinning method for large-diameter composite air cylinder

Abstract

The invention relates to a weldless aluminum alloy lining neck-spinning method for a large-diameter composite air cylinder. Three sets of multi-pass direct spinning composite tracks of oblique line tapering, arc bottom sealing and ellipsoid necking are designed according to the structural features of a large-diameter elliptical end socket and a small-diameter pipe nozzle and the requirement that no obvious fold or other defects exist on the inner surface of the end socket, and the spinning speed and temperature are determined, so that the pipe nozzle is thickened obviously; and the end socket and the pipe nozzle meet machining requirements, the shoulder of the end socket is in smooth transition with a barrel, and no obvious fold exists on the inner surface of the end socket. In addition, a compensation design is adopted in the third set of curve, the corner R of the lining pipe nozzle is obviously thickened, and the reliability of the water pressure self-tightening test and fatigue and bursting performance of the composite air cylinder is increased. Meanwhile, a pipe blank is annealed before spinning, and the inner surface near the corner R of the lining pipe nozzle is polished with a specially-made tool after spinning, so that the risks that folds, cracks and other defects happen to the inner surface near the corner R of the lining pipe nozzle are controlled.

Description

Technical field [0001] The invention belongs to the technical field of manufacturing composite material gas cylinders for aerospace, and specifically relates to a welding-free aluminum alloy lining for large-diameter cylindrical composite gas cylinders, necking spinning forming and process defect control methods. Background technique [0002] The composite gas cylinder for aerospace is composed of a metal lining and an outer composite material winding layer. The weld-free metal lining has demanding weight (lightweight high-performance aluminum alloy), large volume, large diameter, and high dimensional accuracy. After the necking spinning, the inner surface is required to be free of wrinkles, cracks and other defects, which greatly improves the requirements for the necking spinning process. At present, foreign countries have mastered the high-precision seamless aluminum alloy lining closing spinning technology. The American Structural Composites Industry Corporation used the spinn...

AI Technical Summary

Problems solved by technology

For large-diameter aluminum alloy lining closing spinning, the wall thickness of the cylindrical tube blank is generally 6-10mm, and the closing spinning deformation is large, and the nozzle part is easy to be thinned or thickened after single-set curve closing spinning. Obviously, the machining thickness allowance of the nozzle is insufficient, which will easily lead to the scrapping of the product; in addition, when the single set of curves is closed, the thickening allowance at the R corner of the nozzle root is insufficient, and the stress concentration at the R corner of the nozzle root of the composite gas cylinder metal lining , and the composite material of the outer layer of the gas cylinder has no axial force bearing effect on the R corner, and the thickening effect at the R corner is not obvious, which may easily lead to leakage at the R corner of the composite gas cylinder during hydraulic self-tightening, fatigue or blasting tests ; In addition, the currently used closing spinning process makes the inner surface of the lined head (especially the area near the R angle) inevitably have defects such as wrinkles and cracks. The existence of these defects may cause subsequent composite gas cylinders Leaks occurred in self-tensioning, fatigue and burst tests, which became the origin of cracks

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