Research On Process Of Superplastic Forming For Four-sheet Rudder Structure Of TC4 Titanium Alloy

Superplastic Forming(SPF)process is one of the most important research subjects in the area-space engineering field.Due to its unique advantages of increase structural integrity and weight reduction Superplastic forming is a groundbreaking technology of the modern aviation and space industry.The traditional manufacture technology for assembling rudder part of titanium alloy was using riveting,bolting,welding and other connection forms,which has some disadvantages,including large part quantity,great assembly difficulty and poor reliability.The appearance of Superplastic forming technology has changed this connection forms,and it has some advantages over the traditional manufacture technologies in many aspects,such as improving vehicle performance and produce cost.With the improvement of application requirements,more layer,bigger size and more complex hollow sandwich structure is needed.There are much effort have been made in four-sheet SPF structures research.At present,the titanium alloy SPF process has been taken into applied use in China,but there is a great gap compared with developed countries in the SPF technology.As one of the most important parts in the field of Aeronautics and Astronautics,rudder structure has been paid close attention to by scholars all over the world.In oversea,the SPF technology for rudder part was a research hotspot in aerospace industry for ages,and has gone deeply into the substantive engineering stage.but in domestic,it is just at the experimental stage.Therefore,it is very important to use the super plastic forming technology to produce the rudder structure parts and get the optimized forming process.Aiming at the above problems,this paper takes the TC4 alloy as the research object,based on mastering the superplastic forming principle,through the high temperature tensile test and microstructure analysis,combined with the finite element simulation results,in the experiment of superplastic forming machine to complete the trial of four layers of vertical bars type rudder body structure,and analysis the results of trial production.The results show that:in the process route,forming the four layer structure in good condition,no wrinkles or cracks in the surface,in the process of forming panel air chamber and the core plate chamber will appear leakage phenomenon,affecting the forming results.Test to determine the temperature is 875?,the vacuum in the 10-3pa,the maximum forming pressure for the forming process of 3.5Mpa,which provides a reference for the subsequent development of sandwich structure.