The Representation and Three wedge Angles of the Curved Surface of Rotary Tiller Blade

Abstract

1. The three methods which represent shape of the face of a rotary tiller blade with the three wedge angles were shown, and the most simple, accurate and adequate representing method was selected. The first of the three methods is the three planes cutting method in which the action to soil is not considered, the second is the concentric circlar method in which the blade rotates around a point and the third is the trochoid method in which the blade rotates on a horizontal line with traveling.
2. The relative formulas between the three wedge angles by the three planes cutting method and those by the concentric circular method were obtained respectively, and the changes of the three wedge angles due to the change of tilling conditions were qualitatively shown.
3. Three wedge angles on main points of the blade face were measured and compared with among the three methods, and the characteristics of the action to soil and shape of the blade face were explained in comparison with those of the bottom plow share and moldboard.
4. From the above comparison, the followings were made clear. The three wedge angles of the blade face by the trochoid method were slightly smaller than those of plow, the states of their change were quite opposite to ploww and there was no turning action, and the cutting edge-particu-larly front end point (point E or F)-of the blade was main position of the action to soil.