Research On Embossing-head System Of Plastic Chip Hot-embossing Machine

Microfluidic chip is microanalysis device with the advantages of fast,efficient and low-consumption,which can be used to fabricate microchannel structures and other functional units on substrates of several square centimeters.It is widely used in DNA analysis,immunological assays,food inspection and aerospace science and many other fields.Nowadays,polymer materials such as plastics occupy the chip processing field due to their advantages of low price,simple manufacturing process and good processing repeatability.In general,for thermoplastic materials,the hot press has become the key equipment for its channel forming and packaging.Aiming at the problems of low heating efficiency and no vacuum device in the existing hot press,this paper designs a set of embossing-head system using electromagnetic induction heating,which has the advantages of simple operation,stable operation and high degree of automation.First,the current research status and existing problems of hot-embossing equipment at home and abroad are analyzed and sumnarized.At the same time,the application prospect of electromagnetic induction heating technology in the mechanical field is introduced,and the use of electromagnetic induction heating technology to press the existing hot-embossing machine is further explained.The need for a redesign of the embossing-head system.Secondly,in order to improve the rapid temperature rise of the indenter during hot-embossing and the cooling efficiency of demoulding after hot-embossing,based on the research status and analysis of existing problems,a set of heating using electromagnetic induction heating(electromagnetic induction)-refrigeration(circulating water)device,the design scheme of heating-cooling device using electromagnetic induction heating embosing-head system was formulated,and the mechanical structure of the device was designed.At the same time,in order to avoid the influence of the outside air on the quality of the chip's hot-embossing during the demolding process after hot-embossing,a set of partially closed vacuum device based on the heating-cooling device of the electromagnetic induction heating head system was established.The design scheme of the device was formulated,and the mechanical structure of the vacuum device was designed.Thirdly,in order to improve the performance of the hot-embossing machine and better meet the technical requirements of making polymer microfluidic chips such as plastics,Ansys/workbench software was used to analyze the magneto-thermal coupling of the pressure head system,and the analysis results were discussed.The results show that when the coil is lmm away from the pressing head plate,the pressing head plate is made of copper,the induction frequency is 8500HZ,and the cooling water flow rate is 1.2m/s,the system can not only meet the temperature requirement of 150oC in the hot-pressing replication process,but also meet the temperature requirement of 65? when the chip is formed and demold.At the same time,the processing cycle of a chip is three times shorter than that of conventional heating.In addition,in order to realize the automatic control of the of embossing-head system,the temperature control system including the hardware part and the upper computer software part are established.The hardware part includes hardware selection,hardware circuit design,etc.The upper computer sofrtware includes the design of login interface,serial port communication module,data acquisition and visualization module,control module and alarm module of upper computer.The real-time communication between the STM32 MCU system of the lower computer and the labview software of the upper computer is realized,and the real-time and accurate control of embossing-head system is achieved.Finally,in order to improve the temperature control precision of the embossing-head system,the temperature control methods of embossing-head including PID and dynamic PID are designed based on the basic principle and characteristics of PID control,and the realization steps are established.Furthermore,heating test of the embossing-head is carried out based on the two methods of PID control and the test results are analyzed and compared.The comparison results show that the dynamic PID control method can meet the temperature control requirements of the embossing-head system.