Research On Spinning Forming Mechanism And Control Technology Of Absorbable Suture

Since 2004,the demand for medical suture has been growing at the rate of 10%-20%.At present,China surgical suture market demands about 1.5 billion yuan each year,but the localization rate of it is not to 40%.In the production process of the absorbable suture,the diameter is or not uniform that is one of the key factors to measure the suture product quality.In the wet spinning process of absorbable suture of collagen and chitosan materials,in order to solve the problem of its uneven diameter and tensile strength,it is necessary to design a constant tension control system of absorbable suture.It ensures its diameter to meet the requirements of the United States Pharmacopoeia thirty-fifth Edition,and greatly increases the production quality and production efficiency of absorbable suture.Based on a lot of research work,we find that the study on the forming mechanism of absorbable suture and the diameter control in the production process is still blank at home.So this paper introduces firstly the forming mechanism of absorbable suture,the finite element analysis is carried out on the jet nozzle flow field of the mixed liquid by Gambit and Fluent software for numerical simulation.Theoretically demonstrates the feasibility of adjusting the suture diameter by controlling spinning velocity.Based on the study of traditional production process of absorbable suture,the work principle of constant tension control system based on PID is established and the whole structure of the system is designed.The system consists of three rollers tension sensor whose sensitive element is the resistance strain gauge,PID algorithm,variable frequency speed control three-phase motor and touch screen.In this paper,the hardware design,software design and data processing methods of the whole system are studied.PID algorithm is used to reduce the error,realizes the on-line closed loop suture tension control.Control part uses the the Omron PLC as the processing core to storage data and analysis,judgment,calculation,transmission.It achieves communication with the host computer.In the EB8000 Project Manager programming screen,the Parameters can be displayed and set.In order to achieve accurate online measurement,the parameters of the PID aritlhmetic instructions are determined by the PID parameter setting method.Selecting the critical proportion method of field engineering setting method.The tension control experiment,the suture diameter control experiment,the suture comprehensive performance experiment and comparison experiment were carried out.Chitosan-collagen absorbable suture samples meet the requirements of the USP thirty-fifth Edition produced by Vertical tube wet spinning machine which uses the technology to upgrade and transform.The inhomogeneity of diameter and tensile strength is controlled from 25.4%?33.2%to less than 5%.Using the constant tension control system of absorbable suture based on PID,not only can achieve closed loop real time on-line control of the tension of absorbable suture,but also can reduce measurement error,reduce labor intensity and improve production efficiency.The paper is great significance for social and economic benefits of absorbable suture,academic value of the online tension control system.