Differential eccentric gear train transplanting mechanism

As the core component of the high-speed transplanter, the rotary transplanting mechanism first used the eccentric gear to drive the planting arm in the gear box to form the seedling claw track and posture required for seedling separation, seedling picking, seedling pushing and seedling transplanting. In the past, the bisection model composed of analytical formula was used in the research on the inserting mechanism of eccentric gear system, but the model believes that the geometric center distance of eccentric gear and the intersection of the internal common tangent of its two base circles are divided into two segments equally, which leads to the error in the relationship of gear rotation angle. The meshing transmission verification of gear teeth is carried out according to the angle relationship calculated by the bisection model. The working tooth profile of paired teeth will cross or separate the tooth profile that will not occur in actual meshing. By solving the angle relationship of eccentric gear through parametric equation, the calculation formula is different from the bisection model. The differential model of eccentric gear transmission is proposed, but it is also assumed that the geometric center distance of eccentric gear and the intersection of the internal common tangent of its two base circles are equally divided into two segments. The influence of radial eccentricity on the gear angle error caused by the existing transmission model is analyzed. The dynamic simulation analysis of the three arm elliptical gear planetary system transplanting mechanism is carried out by using ADAMS, and the accurate calculation method and application of eccentric gear backlash are discussed. Differential eccentric gear train interpolation mechanism is a new structure proposed after in-depth study of eccentric gear transmission. Three-stage eccentric gear transmission is configured in the same phase around the central wheel in the gear box to form a differential gear train. The eccentricity of eccentric gear is smaller than that of eccentric gear planetary system interpolation mechanism in Japan, which improves the transmission performance.

(1) the unequal division model corrects the intersection or separation of the working tooth profile of the paired teeth under the equal division model. When the number of coordinate points of the working tooth profile of the reference tooth is 5000 points, the coordinate control accuracy of the meshing point search can reach 0.001 mm and the rotation angle error accuracy can reach 0.001 °. The calculation method can obtain a very accurate rotation angle relationship of the eccentric gear.

(2) the angular error of bisection model increases with the increase of gear eccentricity, and the angular error of multistage eccentric gear transmission is amplified step by step. The output angle of all levels of gears around both sides of the center wheel of the fixed shaft eccentric gear system is not equal to the angle of the center wheel at the 180 ° angle, and the absolute angle of the planetary gears on the positive and negative sides does not show a centrosymmetric relationship at the 180 ° angle of the first half cycle and the second half cycle.

(3) applying the unequal division model solution to the transplanting mechanism of differential eccentric gear system, the accurate relative motion relationship between gear box and planting arm can be obtained, and the position and attitude of seedling claw during seedling picking and pushing can be accurately described. The differential eccentric gear system transplanting mechanism does not coincide with the seedling claw trajectory of the planting arm on the forward and reverse sides. When the eccentricity is 0.104 3, the trajectory deviation between the two is not greater than 1.01 mm.

Aiming at the problem of rotation angle error caused by model assumption in bisection model, an unequal model for accurately calculating the rotation angle relationship of eccentric involute gear is proposed and applied to the motion analysis of differential eccentric gear system interpolation mechanism.

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