Research On Modeling Of Clustering Rigid-ball Multi-point Spinning Technology And Its Application

With the development of global manufacturing industry,various industries have put forward higher requirements for sheet metal forming technology,which has promoted the development of sheet metal forming technology to a trend of interactive coupling of multiple forming processes.The Clustering Rigid-ball Multi-point Spinning technology(CRMS)is studied in this paper,which is based on the characteristics of multi-point forming,spinning forming and viscous medium forming.This technology can form complex parts with asymmetrical curved surfaces by replacing the bottom die with different profiles,and the clustering rigid balls are spinning on the surface of the sheet,which has a good suppression of springback,distortion and warpage of the formed parts.Therefore,the technology has high application value in the formation of small batches and personalized curved parts.Now the Single-layer Rigid Ball model(SlRB)is mainly used in the numerical simulation research of this method,but SlRB model cannot reveal the deformation rule and forming mechanism during the forming process of this process,so we need to do further research.In this paper,the Multi-layer Rigid Ball model(MlRB)is established by studying the clustering rigid ball stacking arrangement algorithm.The MlRB model is used to study the process ability of forming spherical curved parts with parameters such as blank holder force,rigid ball size and reserved space of spinning cavity.Taking skull repair as an example,the feasibility of the MlRB model for the formation of asymmetric multi-curvature complex curved surfaces is studied.The specific research contents are as follows:1.The forming principle of CRMS technology is introduced,the geometrical characteristics of the sheet is studied when forming a spherical surface under ideal conditions,and the geometric structure of rigid ball stacking is simplified according to the stacking characteristics of actual clustering rigid balls.Through the simplified geometric structure,a clustering rigid balls stacking arrangement algorithm is derived.And based on the algorithm,the ABAQUS secondary development method is used to establish the MlRB model characterized by the close-packing of multi-layer rigid balls.2.Through the comparative study of the numerical simulation results of SlRB model and MlRB model,and analysis of sheet forming process,sheet morphology and thickness distribution based on experimental results,the simulation results of MlRB model are closer to the experimental results than those of SlRB model.And MlRB model can be more comprehensive and realistically simulate the forming process of the process.3.Based on the MlRB model,the blank holder force,rigid ball size and reserved space of spinning cavity process parameters were studied,and the stress and strain distribution,forming force change,thickness distribution,mold clamping accuracy and morphology of the formed parts were analyzed.The simulation results show that with the blank holder force increasing,the wrinkle defects of the formed surface part gradually disappear,and the stress and strain distribution in the forming region will become uniform.The size of the rigid ball is smaller.The stress,strain and thickness distribution of the formed surface part are more uniform,the defects such as pits and wrinkles are not less prone to appear,and the stability of the technology is better.As reserved space of spinning cavity increases,the forming force required during forming is smaller,and the thickness distribution of the formed part become uniform.4.A case study of 3D prosthesis curved surface of cranial damage was conducted.The prosthesis curved surface was established based on the CT images of the patient.Then the curved surface die was input into the MlRB model and the model was used for forming research.By analyzing the thinning rate,mold clamping accuracy and springback of the formed part,the simulation results show that the complex curved part formed by this method has the advantages of high precision and uniform deformation.It has high application value for the production of small batches of asymmetry and multiple curvature complex curved pieces.