Research On Thermoforming Process Of Elastic Bearing Spacer For Helicopter Rotor

The helicopter rotor connecting mode from the initial hinged type,developed to the ball soft,star flexible,unhinged type and bearing type,the structure tends to be simplified,and the use of spherical elastic bearing connection is an important symbol of the new flexible helicopter rotor system.The 17-4ph steel metal spacer is one of the main components of elastic bearing,and its dimension precision and fatigue property directly affect the performance of elastic bearing.The shape dimension and fatigue properties of the metal spacers are closely related to the forming process,so the forming process of the metal spacer is an important factor that directly influences the performance of the elastic bearing.In view of that high strength of cold for 17-4ph stainless steel and the characteristic of poor formability,the thermoforming technology is use to control its dimensional accuracy,which is studied in depth and obtained from the following result:1.With elastic bearing spacer as the research object,according to the characteristics of hemisphere-forming to analyze the stress state of the spacers formed,analyses the process parameters on mechanical level and material performance parameters on the influence of spacer stamping;2.Through uniaxial tensile test and stress relaxation test method to research the rheological characteristics of 17-4ph and to establish the constitutive equation,the stress relaxation equation and the transient creep equation at high temperature.3.Based on the finite element software ABAQUS to septa forming process numerical simulation,the various process parameters on forming the influence law of spacers,through to the high temperature deep drawing with two kinds of technological scheme for inflatable,comparing the simulation results with blank holder can effectively control of deep drawing forming of wrinkling and thickness uniformity,the technology,simple in structure,convenient in operation,the forming of high efficiency and is suitable for the hot forming of elastic bearing spacer.4.The feasibility of the thermoformwork is verified through the high-temperature drawing and forming test and the gas expansion forming experiment,the qualified shaped piece is obtained,and the shaped piece is mass analyzed,and the thickness error is only 0.076 mm on the basis of excellent surface quality,which is within the range of 0.1 mm required by the instruction.