Numerical and experimental studies on design of multi-lumen tube extruded with drawing and air flow

Abstract

This study represents the design and optimization procedure of a multi-lumen tube used for endoscopic retrograde cholangiopancreatography (ERCP) catheter. The geometry of tip and die for the multi-lumen tube is designed based on numerical analysis of molten polymer and air flow. In particular, this numerical study consider the interaction between the molten polymer and the air flow in the lumen which is the main process variable of extrusion, and analyze the heat transfer and pressure distribution through the air flow for the first time. In addition, to reflect the reality of the multi-lumen extrusion process, the velocity is controlled at the end of the tube ejected to the free surface in consideration of the extrusion process, which is drawn by the puller downstream of the extruder. The shear rate and temperature dependent viscosity of PEBAX 7233 SA01 MED is measured for non-isothermal numerical simulations. The extrusion process for multi-lumen tubes with drawing is simulated using ANSYS Polyflow. The profile of extrudate is numerically predicted with the initial design of the tip and die with the manufacturing parameter is optimized. The predicted profile of extrudate is compared to the target profile with dimensional requirements. The design of the tip and die is modified based on numerical results following the design procedure. To suppress the die swell phenomena, the flow area of molten polymer is increased, and the velocity difference is reduced. Finally, the multi-lumen tube with the optimized tip and die is experimentally extruded and compared to the target profile of the extrudate. It has a good agreement with the target profile and satisfies the dimensional requirements. This design procedure and numerical analysis help achieve the desired target profile of extrudate.