Study On Clamping And Conveying Mechanism For Apple Rootstock Cutting Back Machine

With the increasing area of dense planting of apple dwarf stocks in China,the demand for apple dwarf seedlings has also increased year by year.In the cultivation process of apple dwarf seedlings,rootstocks need to be stubbed in autumn,and earstock grafting is carried out in the next spring.The quality of rootstocks directly affects the survival rate of earstock grafting.Aiming at the problems of excessively high cutting rotation speed of the cutter head of the existing apple seedling stubble machine and the scattered seedlings on the spot.In order to improve the quality and efficiency of the stubble,a clamping conveying mechanism is proposed to assist in the completion of the stubble operation。In order to obtain the safe clamping force range and clamping mode of apple seedlings the biological characteristic parameters of apple dwarfing interstock seedlings were studied.Through the mechanical test of the universal test bench,the radial compressive ultimate load of the cortex of the seedlings is 25～30 N;The moisture content of the seedlings measured by the drying method is(47.61±1.27)%;The maximum static friction coefficient of the seedlings measured by the slope method is(0.64±0.05).According to the mechanical analysis of the contact between the flexible belt and the seedlings,the width of the clamping belt was determined to be 100 mm.A three-dimensional digital prototype model of the clamping and conveying mechanism of the apple seedling stubble machine was established using AIP software,and assembly structure and parameter of the clamping and conveying mechanism were determined..In order to determine the optimal combination of operating parameters of the clamping and conveying mechanism in the flat stubble process,the main parameters affecting the flat stubble quality were determined through theoretical analysis,including the cutter head rotation speed,the seedling inclination angle,and the forward speed.Using LS-DYNA to establish a simulation model of cutter head cutting rootstocks,a three-factor three-level orthogonal experiment was carried out with cutting force as an indicator,and the optimal combination of operating parameters was obtained using response surface method as the cutter head rotation speed 2900 r/min and the seedling inclination angle 15°,the forward speed is 1.5 km/h,and then the optimal structural parameters of the clamping and conveying mechanism was determined.Through the theoretical analysis of the seedling kinematics during the conveying process,it is clear that the main factors affecting the conveying rate are the clamping height,the inclination angle of the mechanism and the speed ratio.Flexible processing of the clamping belt segment,defining the flexible contact between the seedlings and the belt,using ADAMS to establish a "transport mechanism-seedlings" simulation model,carrying out the dynamic simulation analysis of the clamping and conveying,and the belt gap for the stable clamping and conveying of the seedlings was 5 mm,The inclination angle between the conveyor belt and the ground was 30°.The static analysis of the frame showed that the maximum deformation is 0.22 mm,and the maximum stress was 24.31 MPa,which meets the strength requirements of seedling transportation operations.Taking the conveying speed and clamping height as the influencing factors,the indoor test is carried out with the conveying rate index.When the conveying rate was greater than 95%,the optimal solution is that the clamping height was 741 mm,the conveying speed was 0.73 m/s,the cutter shaft and belt the foremost distance was 367 mm.The trial-produced prototype was tested in the field,and the results showed that the qualified rate of the flat stubble cut quality of seedlings was 94.4%,the stability coefficient was 92.7%,and the tearing rate was less than 2.3%;the qualified rate of the flat stubble height was 95.7%and the stability coefficient was 95.3%;The seedling transportation rate under the bottom is 91.8%,and the stability coefficient was 93.1%.The clamping and conveying mechanism changes the cutting process of rootstocks into supported cutting,reduces the rotation speed of the cutter head,improves the quality of the flat stubble,and the seedlings can be stably transported after cutting,which improves the operation efficiency and meets the agronomic requirements of apple seedlings.