Design And Experimental Study Of The Eccentric-type Forest-fruit Vibratory Harvester

Harvesting operation plays an important role in the forest-fruit production. In order toimprove the efficiency of forest-fruit harvesting and reduce the harvesting cost, According to thedraft and close planting patterns of China's orchard and poor mechanized operating conditions,eccentric-type forest-fruit vibratory harvester was studied in this paper.Dynamic model of the harvest machine-fruit tree system and fruit vibration model wereconstructed with the simplified model method. Expressions of displacement, velocity,acceleration, amplitude, phase difference, interia force of fruit and power of the harvest machinewere derived. The results showed that fruit removal was main relationship with responseamplitude of fruit tree and excitation frequency of forest-fruit harvest machine. Consumption ofthe system was proportional to amplitude and the cube of frequency.Main components of the harvest machine were designed and analyzed. Mass moment of theeccentric block was1.2kg m, mach power of the exciting device was2.2kW, and maximumexciting force of the device was14kN. The static analysis and modal analysis results of theeccentric-blocks at three working status (single eccentric-block, double eccentric-blocks withoverlapping angle90°and double eccentric-blocks with overlapping angle180°) showed thatthe maximum stress and deformation of the three working status were5.782MPa and1.538×10-3mm respectively, The minimum value of first-step natural frequency for the threeworking status was2212.9Hz, The three working status of eccentric-blocks can work stably andreliably with good dynamic characteristic. Clamping device with parallel levers structure wasdesigned, the clamping force was3000N and the clamping diameter was90～190mm. In order toadjust the height and extension length of the vibration head, cantilever and lifter of the vibratinghead were designed.Control system of the harvest machine was developed based on PLC and configurationsoftware. The host computer was developed by the touch screen and configuration software ofMCGS to achieve harvesting process monitoring,including the harvesting parameters setting anddisplaying, harvesting program selecting and fault alarming, etc. The lower computer wasdeveloped with SIMATIC S7-200PLC to control the harvesting machine and collect theharvesting parameters. The lower computer was communicated with the host computer throughRS232/485serial port. Test results showed that: the system is user-friendly, reliable running andeasy to operate, it can improve the efficiency of the forest-fruit harvesting and fully meets the design requirements.The prototype of harvest machine was used in walnut harvest experiment. The experimentresults showed that the exciting frequency had significant effect on both trunk amplitude and fruitremoval with significance level0.05. The maximum trunk amplitude (8.83mm) and themaximum fruit removal (92.6%) were observed at frequency of20Hz. Polynomial regressionmodel of the exciting frequency and fruit removal was established. No fruit and tree damage wasobserved below the exciting frequency of20Hz, however, the clamp bark tuned to be moreapparent as the exciting frequency increased. Finally, exciting frequency of19～20Hz wasrecommended in which fruit removal was high(89.5%～92.6%) with no damage of the fruit andfruit tree.