Study on Anti-Friction Mechanism of Canna-Leaf Biomimetic Micro-Textured Fruit Tree

Abstract

Fruit tree pruning is an important part of orchard management. In this paper, the force on and the wear of the pruner in the pruning process were studied with a canna-leaf biomimetic convex-hull pruner. The pruner was formed by laser etching technology. The influence of laser power and scanning speed on the geometric dimensioning of the micro texture was analyzed. The shear force calculation model was built to obtain the positive pressure load during the pruning process, while the model accuracy was verified in the static pressure shear test, and the wear mechanism was analyzed in the wear test. The real pruning process was simulated to compare the worn areas of the textured and non-textured pruners and the number of cuts in fixed wear condition, for proving the wear reduction characteristics of the micro-textured pruner. The results show that: the optimal forming parameters are 70 W 1.6 mm/s (10 mm-diameter branches), 80 W 2.4 mm/s (15 mm-diameter branches) and 80 W 1.6 mm/s (20 mm-diameter branches), and the convex hull spacing is 300 μm. Laser power affects the depth and width of the texture, while scanning speed affects the depth of the texture. The positive pressure on the pruner is proportional to the modulus of elasticity, moment of inertia, cut depth, and bevel angle, whilst it is inversely proportional to the distance from the fixed point of the blade to the positive pressure. The wear test shows that the anti-wear performance of the textured pruner is not obvious at the load of 300 g, while the anti-wear performance of the textured pruner is significant at the loads of 1000 g and 2000 g. The wear mechanism shifts from the abrasive wear in the early stage to more complex oxidative wear and adhesive wear. The actual shear test shows that the textured pruner wears less than the non-textured pruner and enters the stable shear faster.