Study On The Dimension Design Of The Capsule Used In The Powder Hot Isostatic Pressed Ring Parts Based On Numerical Simulation Method

Powder hot isostatic pressing,as a new type of near net forming technology,can form complex parts with comparable mechanical properties to forgings,and has great potential in the manufacture of precision titanium alloy parts in the aerospace field.The capsule is an important mold for the hot isostatic pressing process of powder.Whether the size design is appropriate or not directly affects the size of the molded part.However,the powder hot isostatic pressing process is still in the development stage,and the design of the capsule size is lacking in calculation basis.Therefore,it is urgent to establish a universal capsule size design formula.This article takes typical ring-shaped titanium alloy parts as the research object,adopts numerical simulation and experimental research,and proposes a powder hot isostatic pressing capsule design method for ring-shaped parts.The main work contents are as follows:First,the numerical simulation model of Ti6Al4 V powder hot isostatic pressure was established and its accuracy was verified by experiments.According to the process characteristics of powder hot isostatic pressing,Shima-Oyane yield criterion is used to describe the yield process of powder.Uniaxial experiment was carried out on the Ti6Al4 V powder hot isostatic pressing test piece,and the experimental data was fitted to obtain the Shima parameters of the powder material,and then a numerical simulation model suitable for the Ti6Al4 V powder hot isostatic pressing process was established,and the accuracy of the model is verified by experimental resultsSecondly,the hot isostatic pressing process of the ring without surface features under different capsule sizes was simulated and studied,and the capsule size design formula of the ring was created.When the inner and outer walls are driven simultaneously,the size of the ring after forming is changed by the cubic polynomial and linear function relationship with the size of the inner and outer capsules respectively.According to this rule,the binary cubic system for determining the capsule size is obtained;When the outer wall is driven independently,the minimum wall thickness of the capsule used for shape control is a linear function of the inner and outer diameters of the ring,and the capsule size used for the drive can be derived according to the rule that the total amount of alloy before and after processing remains unchanged.The ring designed by the capsule size design formula created in this paper meets the size requirements.Applying this formula to the design of the capsule of the front section of the engine casing in a Sino-European cooperation project,the resulting molded part can meet the expected size requirements.Finally,the design rule of the size of the capsule used in the ring parts with surface features is studied.Through the research,the design rules of the characteristic part of the ring part with typical characteristics are obtained.By analyzing the deformation,densification,and stress distribution of the features,it is concluded that reducing the wall thickness of the capsule at the feature can effectively improve the relative density;From the forming results of multiple sets of ring parts with features,it is concluded that the design formula of the capsule created from the smooth ring members is still applicable to the ring parts with features.According to this,it guides the design of a large-size capsule part with complex features in the defense basic scientific research project.The resulting molded parts can meet the expected dimensional requirements.