Improvement And Experimental Studies Of Vibration Harvesting Equipment For Buried Shellfish In Tidal Flats

Mudflat shellfish is the main species of mudflat culture in China,and mechanized harvesting is an urgent requirement for mudflat shellfish culture production in China.In order to solve the problems of serious damage to mudflats,poor selectivity of shellfish harvesting and high labor cost,this paper carried out the improvement research of mudflat shellfish harvesting machine based on the previous research,analyzed and measured the indentation characteristics of mudflat substrate,used the joint simulation analysis of discrete element and multi-body dynamics and harvesting test,and improved the design of rolling brush,crank and The design of the brush,crank and travel mechanism was improved,and the experimental study was conducted to determine the reasonable working parameters and harvesting performance of the harvesting machine.The results showed that Liaoning mudflats are harder than Shandong mudflats,and the substrate pressure of Shandong and Liaoning mudflats are 50～65k Pa and230～245k Pa respectively when the φ50 pressure head is applied to 50 mm depth;the pressure-sink model of Liaoning and Shandong mudflats was established to provide the theoretical basis for the improvement of walking mechanism.The roller brush and crank length of the pick and catch mechanism were analyzed,and joint simulation tests were conducted using DEM and MBD.The study shows that the spiral lift angle of the brush and the crank length have a great influence on the shellfish harvesting performance.The effect of brush spiral lift angle on shellfish harvesting performance showed that the average force on the brush was106.79 N at 40° of brush spiral lift angle,and the harvesting efficiency increased by8.82% compared with 30° of brush spiral lift angle.The crank length was 15.62%higher than the crank length of 8mm,and the force on the shellfish was 38.66% lower than the crank length of 12mm;the motion parameters on the harvesting performance showed that the harvesting effect was better when the crank speed was 770～870rpm,the primary brush speed was 45～65rpm and the secondary brush speed was70～110rpm.Based on the single-factor test,the orthogonal test was carried out at different rotational speeds of the first-stage roller brush,crank and second-stage roller brush,and the results proved that the harvesting performance was better when the rotational speeds of the first-stage roller brush,crank and second-stage roller brush were 65 rpm,870rpm and 110 rpm respectively,and the harvesting efficiency was 134kg/h,the crushing rate was 5.25% and the leakage rate was 7.46%,which was consistent with the simulation.The results are consistent with the simulation,compared with the previous generation of harvesting machine,under the same conditions of shellfish culture density,the harvesting efficiency of the harvesting machine increased by117.63% and the crushing rate decreased by 2.09%;for the wet beach operation,when the speed of the primary roller brush,crank and secondary roller brush is 55 rpm,820rpm and 100 rpm respectively,the harvesting performance is better,the harvesting efficiency is 313kg/h,the crushing rate is The extraction efficiency was 313 kg/h,the crushing rate was 7.84%,and the leakage rate was 7.38%.The comparison analysis showed that the harvesting machine was more effective under wet beach conditions.The results of beach and shellfish quality tests after harvesting showed that the average choking rate of shellfish was 2.11%,which was 61.11% lower than that of hydraulic harvesting,and the average return rate of juvenile shellfish was 92.29%;the sinking depth of the track of the harvesting machine was <4cm;comparing the penetration force and shear force of 5～15cm before and after harvesting,it was found that the penetration force was reduced by 85.71%,10 cm and 15 cm after harvesting when the depth was 5cm,10 cm and 15 cm,respectively.The shear force was reduced by 65.13%,5.32% and 0.46%,while the penetration force was reduced by 85.71%,55.31% and 27.13% respectively.The impact of the harvesting machine on the beach substrate was small.