Design,Modeling And Experiment Of Micro-Ejection Dispensing System Based On Compliant Mechanism

With the rapid development of cutting-edge fields such as life sciences,electronic packaging,and rapid manufacturing,the requirements for transfer operations such as dispensing of liquid materials are becoming higher and higher.Dispensing is one of the most common dispensing operations,and it is in different fields.There are different requirements for the speed,accuracy and volume consistency of the glue.The traditional dispensing system is limited by the working principle and driving mode.Although it develops earlier,due to its short dispensing speed and large droplet size,it is difficult to achieve the requirements of accurate and rapid injection.The micro-injection dispensing system based on the compliant mechanism utilizes the inverse piezoelectric effect of the piezoelectric material to drive,and has the advantages of fast dispensing frequency,high dispensing precision,high frequency response,etc.,and is widely used in electronics and manufacturing fields,especially In the field of electronic packaging.In view of the shortcomings of traditional dispensing methods,such as slow dispensing frequency and narrow viscosity range of sprayable glue,two types of micro-injection dispensing systems were designed using different amplification principles,and performance analysis and experimental tests were carried out.To improve the problem of poor consistency of the droplet size,establish an estimation model of the droplet volume and perform error compensation.The main contents are as follows:Aiming at the problems of short needle stroke and narrow range of sprayable glue viscosity in traditional dispensing system,a new type of piezoelectric micro-injection dispensing system is designed based on the compliant mechanism.The system consists of glue supply device,driving device and striker valve.The movement characteristic of the dispensing system is that the elastic deformation of the compliant mechanism drives the reciprocating linear motion of the striker to realize the opening and closing of the striker valve,and the micro-injection dispensing function is completed.The driving force,output displacement and frequency characteristics of the dispensing system were obtained by the pseudo-rigid method.The results show that the maximum driving force,output displacement and frequency of the system are 56.4 N,808 ?m and 245 Hz,respectively,indicating that the designed dispensing system can Meet the required driving force,stroke and dispensing speed.The prototype of the dispensing system was fabricated.The effects of the duty cycle,amplitude,frequency and viscosity of the driving voltage on the diameter of the droplet were analyzed by experiments.The conditions for forming the normal droplets were obtained.The experimental results showed that the system showed The highest dispensing frequency is 210 Hz,the minimum droplet diameter is 630 ?m,and the glue drop consistency error is 5.62%.In order to reflect the relationship between the droplet volume of the micro-injection dispensing system and the glue supply pressure,nozzle diameter,drive signal and viscosity of the glue,the micro-injection dispensing system can accurately dispense on demand,through the molding of the glue The process is analyzed.According to the movement law of the striker during the dispensing cycle,the molding process of the glue droplet is divided into four stages to establish the flow model,and the volume estimation model of the micro-injection dispensing system is obtained.The experimental test system was built to test the accuracy and accuracy of the volume estimation model.The test results show that the volume estimation model can better reflect the relationship between the glue supply pressure,nozzle diameter,drive signal and viscosity of the glue.And after eliminating the most important temperature effects of the influencing factors,the glue droplet consistency error is about 8.6%.Although the estimation model of the droplet volume can predict the droplet volume,in the actual dispensing process,as the dispensing time increases and the dispensing frequency increases,the temperature of the ejection chamber increases to make the actual volume and target of the droplet.The volumetric error is getting larger and larger,which affects the accuracy of the estimation model and the uniform volume of the glue droplets.In order to solve this problem,a volume error compensation model is proposed based on the estimation model of the droplet volume.The model learns the trend of volume error through neural network,establishes its error model,and compensates with compensation algorithm to achieve better droplet ejection effect.The experimental test platform is built to verify the volume error compensation model.The results show that the compensation model can significantly improve the volume error effect,and the glue drop consistency error is significantly reduced.The error range before compensation is [-0.5~5] ?l,the error after compensation.The range is [-0.04~0.08] ?l.The one-way driven micro-injection dispensing system can only realize the one-way driving striker,and the striker return stroke relies on the resilience of the compliant mechanism to close the nozzle.Therefore,the closing efficiency of the nozzle at high frequency is low and the closing effect is poor,and the satellite is prone to occur.drop.In order to solve this problem,a novel bidirectional driven micro-ejection dispensing system using a triangular amplifying mechanism was designed.The micro-injection dispensing system is sequentially driven by two piezoelectric ceramics to ensure the return speed and closing force of the striker.By establishing a pseudo rigid body model of the driving device,the amplification factor and driving force of the driving device are obtained according to the virtual work principle and experimental tests are performed.According to the designed bi-directional micro-injection dispensing system,the prototype platform was built and the performance test was carried out.The results show that the bi-directional micro-injection dispensing system has an operating voltage range of [60-120] V and a maximum driving force of 95.4 N.The maximum output displacement is.The higher the voltage,the lower the frequency,the larger the diameter of the obtained droplet;the glycerin with a jet viscosity of 120 mPa.s at a driving voltage of 100 V and a frequency of 50 Hz,the glue droplet consistency error is 4.73%.The designed piezoelectric bidirectional driving micro-ejection dispensing system has good high-frequency performance and promotes the development of micro-injection dispensing technology.