Development Of 3D Printer For Support Bath

With the development of the population and the diversification of diet,vascular diseases are also growing,so the demand for vascular transplantation and replacement is also increasing.The emergence of tissue engineering provides a solution,but the preparation of vascular scaffold is still a key problem.At present,the additive manufacturing methods widely used in tissue engineering,such as ink-jet printing,laser assisted printing and conventional extrusion printing,still have some disadvantages,such as low efficiency,high price,unable to extrude low viscosity fluid and unable to provide stable support for the printing structure.The 3D printing technology of support bath can effectively make up for the shortcomings of the above methods.In order to facilitate the experimental study of the preparation process of vascular stent,it is necessary to develop a 3D printer for the support bath.The development of the printer is of great significance to the experimental study of the preparation of vascular stent.By analyzing the forming principle and process characteristics of 3D printing technology in support bath,the overall scheme of mechanical platform of 3D printer in support bath was designed,and the expected index of mechanical part were determined.Considering the stability requirements of the support bath in the printing process,the layout of the motion axis was designed,and the support bath forming platform was placed in the vertical direction to control the printing layer height.According to the process requirements,the extrusion heating device,double nozzle switching device and molding platform of the mechanical platform were designed respectively,and the virtual assembly of the whole machine was completed.The modal simulation analysis was carried out by using Workbench to avoid the resonance when the equipment is running.The mechanical platform was built by machining and assembly,and the modal frequency of the whole machine was measured by experiments to verify the correctness of the simulation analysis.According to the requirements of functional parameters,the main controller and other hardware were selected.Considering the working characteristics of the hardware and the connection of the circuit,the design of the control cabinet was completed.Based on SKTOOL 6.2 version configuration software matched with PLC controller and combined with PLC programming,the man-machine interaction interface design of control system motion control,temperature control,air pressure monitoring and printing process control were completed,and the functional requirements of 3D printer were realized.Among them,the temperature control system adopts logic comparison control mode to realize the temperature control of extrusion heating device and molding platform.The air pressure control system was designed two separate air supply channels.The pressure regulating valve controls the pressure and the two position three-way solenoid valve controls the material extrusion.The performance of temperature control system and air pressure control system were tested and corrected.Because the real-time acquisition position of the temperature sensor is not the working face of the heating device,the temperature of the heating working face of the extrusion heating device and the molding platform were corrected respectively.By adjusting the control parameters and analyzing the collected data,the linear compensation method is used to compensate the initial input temperature setting value,so that the control accuracy of the extrusion heating device can reach ±1℃,and the control accuracy of the molding platform can reach ±0.5℃.The air pressure control system can ensure the stability of air pressure by adding a pressure stabilizing valve with the pressure stabilizing accuracy less than or equal to 0.07 Kpa in the air circuit,and reduce the fluctuation range of air pressure from ±6Kpa to ±3Kpa.The reason of large fluctuation range of air pressure is analyzed.The fluctuation range was reduced to within ±1KPa by replacing the small range air pressure transmitter,which ensures the stability of material extrusion.The printing performance of the printer was proved by 3D printing,curing,extraction and measurement of the hollow tubular structure.