| Sapindus mukorossi is a forest fruit with high economic value.The main component of Sapindus pericarp is saponin,which can be used to make hand washing soap,cosmetics,etc.The main extract of saponin has a certain medicinal effect and can be used for antibacterial and anticancer purposes.The seed kernel has high oil content and has broad development prospects as a new raw material for biodiesel However,there is not a shelling machine with good shelling effect on the market at present.Some existing shellers are replaced by other fruits shellers such as camellia and peanuts,or manual shelling,with low shelling rate and working efficiency.In this paper,the viscoelastic properties of Sapindus mukorossi pericarp were tested and measured in view of the interference of the viscosity of Sapindus mukorossi pericarp on the work of the shelling machine,which provided theoretical support for improved design of the shelling machine.In addition,a roller-press shelling machine for Sapindus mukorossi was improved and its shelling effect was measured through experiments.The main research contents and conclusions are as follows:(1)The viscoelasticity of Sapindus mukorossi pericarp was measured.Static creep test showed that pericarp strain was positively correlated with moisture content.The dynamic shear tests showed that the pericarp with moisture content of 11.00% had the largest loss tangent value and was more prone to viscous deformation when subjected to external force,while the pericarp with moisture content of 0 had the smallest loss tangent value and was more prone to elastic deformation when subjected to external force.The frequency increases from 0.1 Hz to 100 Hz,and the pericarp will produce more viscous deformation when subjected to external force.The temperature rise within a certain range makes the pericarp with moisture content of 18.78% more elastic deformation when subjected to external force.However,the pericarp with moisture content of 6.50%-7.50% has more viscous deformation.Scanning electron microscope observation of the pericarp found that the main elements of the pericarp were carbon,oxygen and potassium.With the decrease of moisture content,the cells in the pericarp gradually changed from a round shape with orderly arrangement to an irregular shape with disordered arrangement.Water loss led to closer arrangement of substances,and the pericarp was more likely to deform elastically when subjected to external force.(2)The optimization design of roll-press Sapindus mukorossi sheller was carried out.Viscoelastic tests verified the importance of blade cutting in the shelling process,thus add the mandatory cutting process.The DC motor drives the two blade groups to form a feeding distance,which can adjust the speed respectively to realize differential operation.In order to prevent the pericarp from adhering to the roller too much,Teflon(non-stick coating)material plate was selected to wrap the roller and curved plate,and tooth grooves were processed on the outer surface of the plate to improve the extrusion effect.In order to make it easier to adjust the distance between the spring and the roller,screw bolts were used to adjust the extrusion degree of the spring,thus adjusting the distance between the curved plate and the roller.In order to improve the effect of vibrating screen,vibrating motor is used instead of eccentric block to drive vibrating screen.(3)The performance of the improved sheller was tested.The optimized working parameters determined by experiments are as follows: the blade shaft speed is 0r/min for the upper blade shaft and 120r/min for the lower blade shaft;the intervals between the blades are 8mm for the upper blade group and 4mm for the lower blade group;the distance between the two blade shafts is 58mm;the distance between Teflon roller and curved plate is 315 mm.The results showed that the cutting rate can up to 94.00%,the complete shelling rate of the fruit can up to 91.33%,and the correct separation rate of the vibrating screen can up to 93.67%. |
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