Optimization Design And Experiment Study On The Die Sleeves Of The Nested Ring-die Structure Of Forage Briquetting Machine

The structure of die plate on traditional vertical ring molding machine always made up of splicing module,which has the problem of poor compression molding of forage and excessive wastage of worn die plates.Therefore,a nested die plate structure on the ring molding machine is proposed in this thesis.(1)Based on the working principle of the ring molding machine,a nested die plate structure was designed,which was a type of mold sleeve with ring die holes embedded in the frame of die plate.The separation structure of the ring die holes and the die plate made the optimization of the die hole size and the wear problem all transferred from the die plate to the mold sleeve.This structure can ensure replace the conveniently after wear,the excessive waste of material was avoided,and the repeated use of the mold plate was realized.(2)An open compression test rig was designed with flexible replacement of the die sleeve,realized single axis open compression in the mold sleeve.The open compression test of Leymus chinensis reveals that the process of piston compression can be divided into piston filling stage,piston compression stage and piston pushing stage stage.Because of the effect of cone angle,the pressure and the density increases when the grass blade was squeezed into the die hole,and the pressure shows a tendency to fluctuate due to the change of dynamic friction.Through the effect of temperature research,it was determined that the optimal environmental temperature for Leymus chinensis compression is 120?.(3)Based on the open compression test rig,the full factor test of the square cone die hole and single factor test of conical die hole were carried out,the length of the entrance,the length of the cone section and the length of the straight section were taken as the influencing factors,and extrusion pressure,specific energy consumption,bulk density and compressive strength were taken as evaluation indexes.The results show that when other conditions are fixed,the extrusion pressure and specific energy consumption increase with the increase of the length of the entrance and the length of the straight section,while the density and the compressive strength of the grass increase with the increase of the length of the cone section and the length of the straight section.The optimum square cone hole size of compressed Leymus chinensis was determined that the length of the entrance was 24 mm,the length of the cone section was 30 mm and the length of the straight section was 80 mm.Alfalfa has higher protein content and less fiber than that of Leymus chinensis,which gives a better performance on shaping.The die cone angle played a leading role in extrusion pressure and specific energy consumption,while the total length of the die hole played a leading role in the density and compressive strength.(4)Using the discrete element method and based on the EDEM simulation software,the model of the forage grass compress particle and the contact model between the elastoplastic model and the cohesive model were established,and the compression process of the powder particles was analyzed.The results showed that when the particles were pressed into the die hole,the density decreased from top to bottom,and the compressive force increased first and then decreased.The average compressive force of particles in the cone section was generally greater than that in the straight section,and the average compressive force of particles in the junction between cone and straight segment was the greatest.Under the same aspect ratio,the smaller the die hole diameter,the greater the pressure required,the greater the interaction force between particles,the better the compression effect for particles.(5)The design and trial production of the nested ring molding machine have been completed.The productivity of the machine was 1300 kg/h,the power consumption of tons was 37 kWh/t,the density of the grass block was 1150.77 kg/m3,and the durability was 96.47%.The performance test showed that the machine can achieve continuous and stable production of compact compression of Leymus chinensis.A dense pasture molding production line was built using the nested ring molded block prototype as the main body.This production line had realized a series of technological processes,such as grit crushing,dustproof settling,screw feeding,feed feeding,compact forming and cooling storage to satisfy the compression molding of different kinds of materials.