Study On Numerical Simulation And Process Of Balloon Molding

Balloon catheter is one of the most important medical devices for the treatment of cardiovascular diseases.The balloon is the heart of the balloon catheter and plays an important role in the expansion of blood vessels and delivery of stents.In today's society,cardiovascular diseases often appear.Balloon demand is growing in the direction of larger and diversification.At present the forming of balloons is something of a black art.The development of the new balloon needs to consider many factors such as the size of the tube,the size of the mold and the molding process conditions.The traditional trial and error method has the disadvantages of long cycle and high cost and can not meet the needs of market competition.The method of numerical simulation provides a new idea for the study of the mechanism of balloon forming.In this paper,a general nonlinear finite element software was used to simulate the PA 12 balloon forming process,The numerical simulation results were compared with the actual forming results,and the correctness of the numerical simulation was verified.On this basis,the following research contents are as follows:(1)Through single factor analysis,the influence of the process parameters,the size of the parison and the mold on the wall thickness of the forming balloon was analyzed;Then,the influence of process parameters on the wall thickness of the forming balloon was analyzed by orthogonal experiment.The results of single factor analysis showed that the greater the stretching speed,the smaller the wall thickness of the balloon;There is a nonlinear relation between the bulge pressure and the wall thickness of the balloon;The larger the length and thickness of the parison,the greater the wall thickness of the balloon;The greater the taper angle of the die,the smaller the wall thickness of the balloon.The results of orthogonal experiment show that the first stretching speed has the greatest influence on the wall thickness of the balloon.(2)Based on the analysis of the wall thickness of different tubes,we find that they are linearly related under certain technological conditions.For the production of a balloon under similar process conditions,the fitted linear relationship can be used to determine the wall thickness of the tube.Based on the results of orthogonal experiment,the relationship between the forming parameters and the wall thickness of the balloon was obtained by nonlinear fitting method,it can be used in actual production to adjust and determine process parameters.(3)According to the relationship between the thickness of the tube wall and the wall thickness of the balloon,the wall thickness of the tube is determined by means of the prediction/correction method.The predicted/corrected method determines the tube wall thickness values very close to the linear relation determined by the tube wall thickness values,although it is less convenient than linear relationship,but it is suitable for different process parameters.(4)Structure of the water jacket which is the main forming equipment in the balloon forming machine was improved.Through numerical simulation,it was proved that the improved runner structure is more reasonable and efficient.