A Method of Eliminating Wrinkling of Large Curved Surface Based on Gradient Gap Die

Abstract

The invention discloses a method of eliminating skin wrinkles of a large surface based on a gradient gap die and belongs to the field of techniques of removing skin formation wrinkles. Batch production of high-quality skin can be implemented herein by optimally designing die gaps and manufacturing; the method herein is applicable to the formation of skin parts of various high-intensity materials,particularly manufacturing of titanium alloy skin parts; pressure-pressure stress state is a main cause to wrinkling; gaps are reasonably designed, gradient frictional resistance is utilized to form acontrollable resistance field, and therefore, mobility during plate forming process is limited, the pressure-pressure stress state in plates is reduced, wrinkle removal is achieved, and high-qualityparts with corrugation meeting technical requirements are met. The method herein may be used as a new method to eliminate wrinkles in thermal formation of titanium alloy large-surface skin so as to obtain high-quality parts.

Description

technical field [0001] The invention belongs to the technical field of eliminating wrinkling in skin forming, in particular to a method for eliminating wrinkling in the thermal forming prefabrication process of large curved aircraft titanium alloy skin. Background technique [0002] The improvement of aircraft maneuverability puts forward higher requirements for aerodynamic shape, and curved skin is an important outer covering part in the aviation industry. The forming process is determined according to the material characteristics: thin aluminum alloy skins are drawn by multi-point flexible molds, composite material skins are formed by hot pressing, and high-strength stainless steel, high-strength aluminum alloys, titanium and titanium alloy skins are mostly heat-formed. Way. Thermoforming refers to a pressure processing technology that heats metal materials above the recrystallization temperature and utilizes the characteristics of metal materials to increase plasticity a...

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Problems solved by technology

[0004] Domestic existing patents on aircraft skin forming mainly focus on tooling and normal temperature forming methods: CN201710939493.9 discloses a hot drawing device and its forming process, which uses the properties of titanium alloy materials for uniform drawing, but only for simple curved surface It needs to fix the blank, and the continuous productivity is poor; CN201711494930.7 discloses a normal temperature drawing device and compound milling processing method, but it is not suitable for the forming of high-strength materials, which consumes a lot of energy and cannot control springback; CN201710538209.7 discloses A method for aircraft skin stretching is proposed, which uses the method of changing the film to reduce the curvature and gradually stretches, reducing the problems of overdrawing and wrinkling. The procedure is complicated and not suitable for high-strength materials.

CN201610862099.5 discloses a combined process method of Mongolian drawing forming and liquid filling forming. The complex structure improves production efficiency but is not suitable for high-strength materials with poor plasticity at room temperature

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