Abstract
The objective of this research is to design and construction rotary
blade for reducing soil impacted-resistance forces. There are
three important portions of a rotary blade, namely lengthwise, tip
and holding blade portions. This paper presents how to design
prototype rotary blades. The lengthwise blade portion is designed
straight in order to simplify the production process. The tip blade
portion is designed for cutting and throwing soil. As well, it
contains slice angle to avoid every portion of the cutting edge
from impacting the soil surface at the same time. And it also
contains scoop surface to avoid the abrasion of blade’s outer
surface from the soil, hence reducing the soil resistance. In
experiment, slice angles of 10°, 15°, 20° and 25° are designed in
order to determine the relationship between the impacting forces
with slice angle and the rotational angle of rotary shaft. Four
prototype blades with different slice angles are then tested on the
testing set EOR (Extend Octagonal Ring) composing of a moving
soil bin and a stationary rotating rotary shaft. The experiment’s
results showed that every design of the blade gives satisfying flat
tilled-soil bed and tillage depth of 15 cm. At tillage pitch of 4 cm,
the increasing of slice angle from 10° to 25° results in a
significant decreasing of the reaction force. The maximum
reaction force for the blade with the angle of 20° decreases 25%
from that of the one with the angle of 10°. However, increasing
slice angle above 20° can no longer reduce the reaction force.
Whereas for the pitches of 6 and 8 cm, the practical value of
actual soil tillage pitch, the increasing of slice angle from 10° to
25° can slightly decrease the reaction force. From this
experiment, it can be concluded according to the reaction force
and material saving that the designed blade with the slice angle
of 10° is the most appropriate.
Key words: Rotary Blade, Slice Angle, Scoop Surface