Design And Test Of Automatic Harvesting Equipment For Water Grass In Crab Pond

Water grass conservation is the key link of river crab culture,water grass harvesting as an important way to achieve water grass conservation,harvesting quality directly affects the morphology and yield of river crab.At present,because of the lack of effective small harvesting equipment,most of the crabs pond aquaweed are still harvested manually.However,it is difficult to control the amount of cutting by manual harvesting,and the operation efficiency is low,the labor intensity is high,and the harvesting speed is difficult to adapt to the scale breeding of river crab.Mechanization of harvesting aquatic grass has become an urgent need of shrimp and crab breeding scale.This paper developed and designed an automatic harvesting machine for aquatic grass suitable for river crab aquaculture waters,providing reference for the research on mechanization of aquatic grass harvesting in river crab aquaculture waters.The main research contents are as follows:(1)The overall scheme design of aquatic grass automatic harvesting equipment.According to the requirement of aquatic grass harvesting design,the working principle and installation mode of the equipment are determined.The main technical parameters of the equipment are: cutting width of 1200 ～ 1800 mm,cutting depth of 0 ～ 300mm(adjustable),productivity of 3 ～ 5 acres /h.Harvesting equipment is fixed to the hull head and can be connected to any kind of ordinary vessel for easy disassembly and assembly.(2)Design and selection of key components of aquatic grass automatic harvesting equipment.The two kinds of cutters were compared comprehensively,and the reciprocating standard cutter was determined as the final program.The cutter blade was optimized and the cutter parameters were calculated.The eccentric wheel slider mechanism is determined to be the driving mechanism of the cutter,and the transmission mechanism is designed.According to the requirements of working conditions,the cutting platform automatic lifting mechanism is designed,the lifting range is 0～500mm.(3)Design of depth control system for aquatic grass automatic harvesting equipment.A PLC based depth adjustment automatic control system is designed.According to the functions of the control system,the hardware selection and software design of two control devices,the drive module and the sounding module,are carried out.The water depth of the cutter is detected by the liquid level sensor,and the cutting depth is adjusted accurately.Considering the water level fluctuation caused by the operation vibration,the adjustment precision is ±0.5cm.(4)Simulation analysis of transmission system of aquatic grass automatic harvesting equipment.The whole machine model of aquatic grass automatic harvesting equipment was established by using the 3D design software NX8.0ug,and the finite element analysis of the horizontal bevel gear showed that the maximum working stress was less than the allowable stress of 157.73 MPa,and the structure design of the transmission system was safe.According to the structure of the drive system,the mathematical model of the drive system vibration was established.The simulation of the drive system vibration was carried out by using the Simulink module in MATLAB software.The results show that the impact torque caused by the drive system vibration is 3.6N ·m,which is 29% of the input torque of the drive shaft.Therefore,in view of the factors that affect the working stability of the machine,the optimization design is carried out.(5)Performance test of aquatic grass automatic harvesting equipment.In a certain water area of Jiangsu Province,different pond mouth,different varieties of aquatic grass and different cutting depth were selected for the test.The working test lasted for 4 hours,with an area of 5 mu,5.5 mu and 6 mu respectively.The experimental results show that the average harvesting efficiency of the prototype in different environments is 4.02 mu/hour,the water grass leakage rate is not more than 3.3%,the crab injury rate is not more than 0.2%,all of which can meet the design requirements,convenient disassembly and assembly,stable operation.