Optimization and testing of the bionic shaped chopping cutter for silage maize

This study aims to reduce the cutting resistance to the existing chopping blade of silage corn, in order to reduce the slant rate for the high length of standard grass. The pre-biomimetic profile of the beaver incisor was used to fit the characteristic curves of the chopping blade. A systematic analysis was also made to determine some parameters of the blade structure and the movable, as well as the fixed blade configurations. The original profile of the blade with non unibmn ratinalb splime (NURBS) curve was optimized using the least square method (LSM) with geometric constraints. A simulation was then made on Rocky software, in order to clarify the relationship among the edge inclination and rake angle of the convex arc curve, as well as the force and strength of the cutting edge. The resistance was calculated for the three types of knives when cutting straw before and after optimization. The test results showed that the maximum cutting resistance of the optimized bionic blade was 625.05 N, which was 13.42% lower than that of the flat straight blade. The three-factor, three-level orthogonal test was conducted to explore the effect of the key parameters of the curved edge of the chopping blade on the maximum cutting resistance of the silage corn stalks. The bench test showed that the smallest resistance of the cutting blade was achieved when the angle of the outer sliding cutting was 30°, the tilt angle of the blade was 6°, the bevel angle of the blade was 2°, and the maximum cutting resistance of the blade under the parameter of the simulation was 536.79 N, which was 14.86% lower than that of the original biomimetic shaped blade. The quadratic rotation orthogonal combination test was carried out with the operating speed, the gap between the moving and fixed blade, and the spacing between the moving and fixed blade as the test factors, and with the standard grass length rate and the oblique stubble rate as the evaluation indices. The test results show that the standard grass length rate was 93.64%, and the oblique stubble rate was 2.42% when the operating speed was 1.94 m/s, the gap between the moving and fixed blade was 0.23 mm, and the spacing between the moving and fixed blade was 179.39 mm; The field harvesting also show that the standard grass length rate was 95.09%, and the oblique stubble rate was 2.50%, when the operating speed was 1.94 m/s, the gap between the movable and fixed blade was 0.2 mm, and the spacing between the moving and fixed blade was 178 mm. The relative error between the experimental and the optimized values was less than 5%. The standard grass length rate of the commonly used flat straight blades was improved by 13.56 percentage points, and the oblique stubble rate was reduced by 3.06 percentage points. The finding can also provide a strong reference to optimize the chopping blades for silage corn.