Design And Research Of Continuous Rolling And Chopping Device For Tea

China is one of the main tea-growing countries in the world,have all kinds of tea varieties,including black tea,green tea,yellow tea,black tea,white tea,etc.,meanwhile,a great variety of tea products using minced tea raw materials have also been developed such as the fragrance of tea,herbal tea,slimming tea,tea beverage,instant tea,organic tea,tea bag.Therefore the broken tea has great development potential.Two processes such as rolled and chopped are used to make the broken tea While the rolling and chopped process are independently made by a single machine and segmented production,with some defects such as large working intensity,poor particle fineness,low crushing rate,poor clarity,and product quality also exists some difference.Therefore,based on the traditional rolling and shredding process,in this paper a tea rolling and shredding continuous operation device was developed,and the rolling and shredding device was set as a whole;and a control system was developed to achieve continuous automatic rolling and shredding operation for fresh tea,improving the stability of tea quality,ensure that the grain size of chopped tea leaves is within3mm,reducing labor intensity.The main research contents were as follows:(1)The overall structure design of continuous rolling and shredding device for tea fresh.The device structure was mainly composed of rolling device,pressurizing device,conveying device,shredding device,etc.,to achieve continuously rolling and shredding operation.The rolling device was composed of kneading core,ribs,upper kneading cover and lower kneading cover,and the shredding device was composed of spiral conveyor,shredding barrel,straight blade knife,shredding knife,tail plate,shredding flange,hopper and shredding motor.The device was arranged into a vertical structure,and the rolling part was placed above the device,while the shredding part was placed below the rolling part.The fresh tea was rubbed in the rolling device,and tea was crimped and damaged tissue cells,transported to the shredding device through the conveying device,and the continuous shredding process including wringing,squeezing and tearing was carried out.(2)Tea rolling device design.Tea rolling process needs to follow the"light-heavy-light"principle of pressure,therefore the kneading core in the rolling device was designed for the upper,middle and lower three parts,"light-heavy-light"continuous pressure principle was achieved through the shape structure of the kneading core.The kneading core diameter was 500mm,and 12 ribs were used and were installed on the surface of the kneading core located in vertical line 300.The width of the small end of the ribs is 6mm,and the height of the small end of the ribs is 4mm,and the width of the big end of the ribs is9mm,and the height of the big end of the ribs is 6mm.The designed structure can promote the formation of tea rolling motion law and ensure the quality of tea rolling.(3)Tea cutting device design.The cutting device was used realize rough cutting and fine cutting two processes.Thick cutting device straight edge knife thickness was 7 mm,and effective length was 45 mm,and blade length was 30 mm,and width was 17 mm,and edge angle was 30~0.The thcik cutting knives were arranged on the straight edge knife holder according to staggered balance.The length,width,thickness,edge Angle and installation Angle of the cutter of fine cutting device are 120 mm,15 mm,5 mm,21~0 and 4~0,respectively.The strength of the fine cutter was analyzed by finite element method.The simulation results showed that the straight edge cutter and the cutter met the strength requirements.(4)Optimization design of transmission chain.The chain transmission way was chosen as the power delivery way of the device By comsol finite element method,the simulation analysis of chain polygon effect caused by vibration was investigated.And three factors three levels orthogonal test was designed based on chain transmission system parameters(speed,gear ratio and center distance)affecting the polygon effect,and the minimum polygon effect caused by vibration leading to the deformation was used as the optimization goal.When the optimal combination of chain drive parameters was obtained:angular velocity of 5rad/s,sprocket gear ratio of 27/18,sprocket center distance of 350mm,the polygon effect produced by chain drive had the least influence on the stability of rolling pressure.(5)Control system development and prototype test.STM32 was used to devleop a set of control system for tea rolling and shredding continuous operation device,to realize continuously automatic pressure,,continuously automatic rolling and continuously automatic shredding operation.Based on the control system,the rolling speed,rolling pressure,shredding speed parameter were coordinated and real-time control and display were realized.Therefore,different seasons and different characteristics fresh tea could be made by the designed device and the high efficiency of processing and the quality consistency of tea rolling and shredding.Based on the optimized structural parameters of continuous operation device for rolling and chopping tea,a prototype was trial-produced.The prototype test results showed that the continuous operation device for rolling and chopping tea was reasonable,and stable operation,and could automatically complete the kneading and cutting process.