Research On The Process And Quality Control Of Deep Drawing Spinning Of Conical-cylindrical Part Of Ni-based Alloy

Ni-based alloys are widely used in critical components of the combustion chamber of aero-engines and gas turbines,which are subject to high temperatures,due to their excellent comprehensive properties such as high temperature resistance,oxidation resistance,corrosion resistance and rather high temperature strength.This type of parts are often adopted multi-pass stamping to form and heat treatment during the middle pass.However,it is easy to result in serious wall thickness unevenness,which makes it difficult to fulfil the requirements of forming quality and mechanical properties.Shear spinning can produce dimensional accuracy thin-walled conical parts,and deep drawing spinning can reduce the diameter of the blanks and form cylindrical parts without changing the wall thickness.Therefore,the forming methods combined with shear spinning and deep drawing spinning are the most effective methods for producing conical-cylindrical parts with high precision.Because of the large deformation resistance,severe work hardening of Ni-based alloy,it increases the difficulty of deep drawing spinning with conical pre-formed blank.Forming defects such as wrinkling tend to occur during deep drawing spinning,which are subjected to forming properties of this material.This paper takes Haynes 230 Ni-based alloy conical-cylindrical parts as the research objects,and came up with a method of deep drawing spinning to form conical-cylindrical parts from conical pre-formed blank after vacuum solution treatment.Based on finite element simulation and the spinning process experiments,the deformation patterns,forming quality and the criterion of instability wrinkling of Haynes 230 Ni-based alloy conical-cylindrical parts of deep drawing spinning were systematically studied.Based on ABAQUS/Explicit,an elastic-plastic finite element model for deep drawing spinning to form conical-cylindrical parts was established.The distribution and variation of transient equivalent stress-strain,triaxial stress-strain and wall thickness between different passes were analyzed.In addition,combined with different process parameters and heat treatment scheme,the forming defects were summarized and analyzed,and the corresponding control methods were proposed.Moreover,the influence of different process parameters on the spinning process was studied from the change of the equivalent stress-strain extreme value during the forming process.Whereafter,the five indexs including the wall thickness,height,average roundness,springback angle,and straightness of the simulated value and the experimental value of the spun part after spinning forming were compared and verified.Finally,the stress-strain and wall-thickness distribution and changes of the blank after wrinkling,and the influence of different forming parameters on the spinning instability wrinkling were studied.A criterion for spinning instability wrinkling was proposed according to the material stability determination formula in Drucker's Postulate.A user subroutine was written to couple the criterion to the finite element model.The results show that when the spinning process reaches to the mouth of the blank,the maximum transient equivalent stress is located in the contact area of the roller and its vicinity,and the maximum equivalent transient plastic strain is located at the edge of the mouth of the blank.Tensile radial stress,compressive radial stress and tensile tangential stress,compressive tangential stress is much larger than the tensile stress and compressive stress of thickness direction.There is tensile radial strain,compressive tangential strain,and both compressive strain and tensile strain of thickness direction during deep drawing spinning process.The wall thickness of the cylindrical section decreases first and then increases,with the central area reducing the most severe.And the roller feed rate,the space between each pass and the elevation of the first pass have a greater effect on the equivalent stress extreme value,equivalent plastic strain extreme value and regular patterns for two forming defects:instability wrinkling and radial fracture during multi-pass deep drawing spinning.What's more,the roller feed rate,the diameter and thickness of the blanks have significant effects on the position of instability wrinkling,the extreme value of tangential compressive stress and radial tensile stress.After treated by vacuum solution treatment,the conical pre-formed blanks are able to form high-quality conical-cylindrical parts during multi-pass deep drawing spinning under certain process parameters:the roller feed rate f=0.8mm/r,the space between each pass p=5mm and the elevation of the first pass ?₀=40°.