Design And Experimental Research On Piezoelectric-high Pressure Gas Hot Melt Injection Valve

With the rapid development of science and technology,Product packaging requirements are getting higher and higher.In the electronic packaging industry,Products require large screen,large screen ratio and even no border screen,but also requires high mechanical properties and waterproof performance.The packaging of this large-screen electronic products and high-end keyboard are mainly bonded by hot melt.In the book printing industry,hot melt jet dispensing technology compared to the traditional book binding technology has the following advantages,high glue usage,jet dispensing pressure adjustable,so that glue and paper fiber full bonding,the end of the thickness of only one-third of the traditional process,The process of packaging the books,the inside pages can be opened 180 °,completely tiled on the table,improving the fun of reading.In the carton packaging industry,hot melt jet dispensing technology relative to the contact with a high efficiency,low surface roughness requirements,low nozzle wear and other advantages.At present,there is a growing demand for hot melt adhesives on the market,but most of the existing technology is difficult to meet their needs.Only a few foreign companies have to master the technology,but strict technical blockade is imposed on China,which makes machine prices remain high,while the latter part of the high maintenance costs,long cycle,seriously hindered the technology marketing.Therefore,this paper presents a hot melt jet dispensing technology with high precision,high efficiency,no air bubbles and low wear.The analysis of this technology is as follows:First of all,this paper presents the background of hot melt jet dispensing and the occasion of the application.On the domestic and foreign hot melt jet dispensing technology in accordance with the different classification criteria into several categories,and then summed up its advantages and disadvantages.The present situation of hot melt adhesive was introduced,and pur type hot melt adhesive used in this paper was selected by contrast.Then,the piezoelectric materials and the composition of piezoelectric stacks is introduced,and the output characteristics of piezoelectric stack are introduced.The theoretical basis is put forward for the analysis.Secondly,this paper introduces the structural composition and dispensing principle of Piezoelectric-High Pressure Gas Hot Melt Injection Valve.The flow characteristics of the hot melt adhesive in the nozzle are determined,and the flow characteristics of the laminar flow in the cylindrical hole are described in detail.The conditions of the fluid jet dispensing are introduced according to the formula.The general structure of the nozzle was determined by Fluent analysis of different fitting valve needle nozzles and nozzles with different conical angles.Based on the experience of the previous nozzle design and theoretical analysis,a nozzle with good sealing performance and small loss of fluid resistance was designed.Furthermore,the structural design,dynamic analysis and simulation analysis of Piezoelectric-High Pressure Gas Hot Melt Injection Valve are carried out.The displacement of the stem is determined according to the theoretical analysis and Fluent simulation.The stem displacement and the output displacement of the piezoelectric stack are known.Lever is designed by using the principle of lever enlargement,and the static analysis is carried out with Ansys software to verify the rationality of lever.The dynamic analysis of the whole piezoelectric actuator is carried out,and the relationship between the stiffness of the piezoelectric stack and the stiffness of the spring is analyzed by Matlab.In order to prevent the heat transfer from the hot melt adhesive system to the piezoelectric stack,the insulation element is designed and the thermodynamic analysis is carried out with Ansys to verify the heat insulation effect.Finally,install the test prototype,and according to the experimental requirements to build a test platform.The driving voltage of the piezoelectric stack is adjusted,and the displacement of the stem corresponding to different voltage is measured by laser measuring instrument.The measured data is analyzed and the rationality of the design of the amplification system is verified.Then,the pressure of the device,the driving voltage of the piezoelectric stack and the heating temperature were changed to investigate the effect on the jetting performance.Keep the parameters unchanged,repeat the experiment to verify the accuracy of hot melt adhesive device.According to a large number of experiments to verify the rationality of the prototype design.