Studies on Lifting Type Digger for Root Crops (III)
Effect of digging blade in bare sand dune
1978 Volume 40 Issue 3 Pages 361-367
Details
1978 Volume 40 Issue 3 Pages 361-367
As the fundamental studies of lifting type digger development, the pulling resistance force and sand surface displacement were measured in bare sand with the lapse days after tillage by using a portable pulling device attached to digging blade.
The followings were obtained.
1. The pulling resistance force P (kg) had high correlation with cutting depth d (cm), and was greatly influenced by soil moisture content ω (%), but was not affected by the increase of days after tillage.
2. Specific resistance k (kg/cm2) was at the range of 0.04 to 0.14 and increased almost linearly with increase of depth d (cm) of cutting, from 7 to 22.
3. It was often observed that the vertical displacement of sand surface had a varying point V2 after slight vertical displacement in front of thedigging blade. It seemed that the soil shearing occurred on the line connecting the varying point V2 and the digging blade point B.
4. Horizontal distance L1 (cm), from the digging blade point B to the first slight varying point V1, increased with increase of cutting depth d (cm), but was not influenced by the cutting angle θ (degree) and the shape of digging blade. The vertical displacement over the digging blade point HB(cm) increased with increase of cutting angle θ (degree) of digging blade and had a tendency to decrease with increase of the depth d (cm).
5. The shear angle φ1 (degree) between horizontal line and the straight line connecting the varying point V2 and the digging blade point B was at the range of about 20 to 55 (degree) and increased with increase of the depth d (cm), from 7 to 22.
