The Study And Parameters Optimization Of Extrution Blow Molding For Medical Headboard

At present,extrusion blow molding technology is developing rapidly and widely used.However,the mechanical properties of extruded blow products are poor due to the existence of a large area of hollow parts.At the same time,the uneven distribution of wall thickness of extrusion blowing products is an important bottleneck restricting the development of extrusion blow molding technology.Therefore,it is of great significance for the research and optimization of extrusion blow molding.The research object of this paper is the headboard of a medical electric bed,which belongs to the typical complicated non-axisymmetric plate extruded blown products.Aiming at solving out the problems of poor mechanical properties and uneven distribution of wall thickness,it is decided to use CAE software to analyze the structure of medical headboard and extrude blow molding.The molding process is optimized to ensure the molding quality and meet the requirements of its use.Based on the statics module of ANSYS Workbench software,the structure of medical headboard is analyzed,and two ways to optimize the structure of medical headboard are put forward.The effects of four structural design parameters on the maximum deformation and stress value of the medical headboard are studied by orthogonal test.The four structural parameters,the upper and lower corner radius,the width and the spacing of the developed stiffeners,are studied.The experimental results show that the force value corresponding to the radius of the upper corner of the visible reinforcing rib is the most important,while the width has the greatest influence on the deformation,and then the optimum structural design parameters are determined.Finally,the mechanical strength of the medical headboard is improved effectively and the application requirement is satisfied by comparing the invisible reinforcement rib with the corresponding structure.Based on Polyflow software,the influence of process parameters on the thickness uniformity of medical headboard is analyzed.The effects of process parameters on the uniformity of product wall thickness are studied by orthogonal test.The results show that the degree of influence on the uniformity of wall thickness is as follows: the initial thickness of the parison,the time of blowing,the pressure of blowing and the initial temperature of the parison;Then the initial thickness of the parison,blowing time and blowing pressure are selected as the design variables,and the optimal process parameters are determined by the response surface method(RSM).By synthesizing the results of orthogonal test and response surface method,the uniformity of the wall thickness of the medical headboard is improved significantly.In practical production,the initial wall thickness of the parison is adjusted according to the shape of the product and the opening clearance of the die is controlled by the wall thickness controller,so it is necessary to reverse design the opening width of the die.Based on the Polyflow software,the axial wall thickness distribution of the initial parison is gradually optimized,and the uniformity of the wall thickness of the medical headboard is further improved,and the initial axial wall thickness distribution corresponding to the target value of the axial wall thickness distribution of the workpiece is obtained.On the basis of this,the opening width of die is modified continuously and the die opening width corresponding to the initial axial wall thickness distribution value is obtained,which can guide the adjustment of the wall thickness controller.Through the optimization of the structure design of the medical headboard,the simulation study on the parison blow expansion stage and extrusion stage of extrusion blow molding,the molding quality of the product has been improved significantly.The problems of poor mechanical properties and uneven distribution of wall thickness of complex non-axisymmetric plate extrusion blowing products are solved,and effective guidance is provided for the production of industrial extruded blowing products at the same time.