Kinematic Analysis of the Cutting Tool of a Sickle-Bar Mower

Abstract

Sickle-bar mowers are mainly employed when harvesting forage. To improve their quality and consumption indicators, it is necessary to study the trajectory of movement, speed, and acceleration of the mower leg under changing terrain conditions. For this purpose, a study is performed to analyze the effect of the offset on the quality and energy indicators of the cutting equipment of the mower, as well as control the parameters and operating modes of the mower knife with an axial knife drive mechanism. The experimental results show that the cutting tool in the process of creating a relief contour changes the angle of inclination relative to horizon within ±15°. In this case, the offset ranges from 0.281 to 0.492 m. A change in the offset entails a change in the stroke, speed, and acceleration of the knife. Using the Artobolevsky analytical method of kinematic study of eccentric crank mechanisms and Excel calculations, we obtained graphic data on the dependence of the stroke, speed, and acceleration of the knife on the angular position of the cutting tool with an interval of 0°, 5°, 10°, and 15°. Changes in the position of the cutting tool of up to 15° leads to unequal speeds of the forward and reverse stroke of the knife, and also increases it from 76.2 to 89 mm, which increases the energy consumption for the knife drive to 17%. Another disadvantage of the eccentric crank mechanism of the knife drive is its dynamic imbalance, which is only partially smoothed out using a counterweight. To eliminate the disadvantages, an experimental mower with an axial arrangement of the crank mechanism on the bar of the cutting tool is proposed, allowing the bar handles to be transformed to the transport position in the working mode of the cutting tool when driving around bushes, trees, or rough irregularities.