Research On Friction Reduction Mechanism Of Fruit Tree Pruning Tools Based On Bionic Convex Hull

Fruit pruning is an important part of orchard management.Reasonable pruning can improve fruit quality and yield.In pruning fruit trees,due to the variety of branches and leaves,hardness,pruning process is easy to cause tool damage,increase pruning costs,not conducive to the modern development of orchard.It is of great significance to improve the wear performance of pruning tools and increase the service life of the tools for fruit tree harvesting.In this paper,the shear force of sk-5 high carbon steel cutting tool is calculated to improve the wear performance of the cutting tool.The microtexture of the shape of banana leaf was etched by laser on the surface of sk-5 cutting tool based on bionics principle,the wear of the texture-free tool and the textured tool was analyzed by friction and wear testing machine,and the wear resistance of the textured tool was verified by using the intelligent shear test platform.The main contents and conclusions of this paper are as follows:(1)For cutting tools in different shear 10/15/20 mm diameter of the branches of the concrete stress distribution,the elastic foundation beam theory was used to construct the shear stress calculation model,cutting tool by positive pressure and the elastic modulus,moment of inertia,cutting depth,the blade is directly proportional to the Angle,and the constant dao support point to the positive pressure is inversely proportional to the distance,to calculate the different diameter of the branches of the theory of peak stress for303/1066/2675 N.Shear verification tests were carried out on branches with different diameters on the shear platform of the self-made universal testing machine,and the actual peak force on branches was 415/1632/1910 N.(2)The microtexture morphology of banana leaf was etched by laser on the surface of sk-5 cutting tool.The laser etching test was carried out.When the bionic microtexture was at laser power of 70 W and scanning speed of 3.2mm/s,the optimal shape parameters of the microtexture were obtained: convex bag spacing was 300 meters,convex bag width was 135 meters,convex bag depth was 15.4 meters.(3)On the basis of the optimal forming micro-texturing tool size parameters,the laser power is adjusted to 60/70/80 W and the scanning speed is 1.6/2.4/3.2mm/s to obtain microtexturing tools of different sizes.Wear tests were carried out on non-textured tools and textured tools by ht-500 high temperature friction and wear testing machine.The wear test shows that the optimal friction coefficient of the texture cutter is 0.1209 under the load of2000 g and power of 80 W and 1.6mm/s.The texture tool under 300 g load was similar to the non-texture tool,and the texture tool under 70 W power showed a slight anti-friction effect of1.5%.The friction coefficient of textured tool at 80 W power under 1100 g load was the lowest at 0.2378,which was 65.87% of the friction coefficient of texture-free tool.The study of volume wear shows that: under the load of 300 g,the minimum volume wear of textual-free cutter is 11.8189 mm~3.Under the load of 2000 g,the maximum volume wear of texture tool with 80 W power of 1.6mm/s is 83.2349 mm~3.In the 300 g load,the maximum volume wear of texture tool with 80 W power 3.2mm/s is 35.9052 mm~3.In the 1100 g load,the maximum volume wear of texture tool with 80 W power of 1.6mm/s is 42.9274 mm~3.(4)The wear mechanism of texture tool was analyzed by scanning electron microscope and gamma-ray spectrometer,and the friction reduction mechanism of texture tool was further revealed.Under the load of 300 g,the appearance of the wear marks is not obvious,no obvious scratches and tears are formed,and the wear mechanism is simple wear of abrasive grains.Under 1100 g load,the anti-wear performance of the tool is significant,and the texture surface is obviously worn.C,O,W and other trace elements appeared,and the wear mechanism was complicated.Under the load of 2000 g,the wear marks are the most obvious,the texture tool has obvious wear resistance,and a large number of micro elements appear on the texture surface.The wear mechanism is transformed from abrasive wear to the compound wear of oxidation wear and adhesive wear.(5)The microtexture tool with the best anti-friction effect under the corresponding load was obtained through the wear test.Using the self-made intelligent shear test platform,shear tests were conducted on the non-texture tool and the texture tool with three diameters of longan branch(10mm,15 mm and 20mm)at the power of 70 W,1.6mm/s at the power of 80 W,2.4mm/s at the power of 80 W,and 1.6mm/s at the power of 80 W.The experimental results show that when cutting branches with the same diameter,the texture tool can reach the wear stable period more quickly and the wear area is lower.With the increase of the diameter of the branch,the wear reduction effect of the micro texture tool is obvious.The larger the diameter of the branch,the more significant the wear reduction of the texture tool.