Abstract
In order to obtain the data on the design and utilization of rotary mowers, an apparatus of measuring cutting energy was made for trial. The effects of the cutting energy on the bevel angle of knife, the cutting speed and the diameter of pasture stalk were investigated. After the rotary knife cut off the pasture, the speed and energy of rotation went down. Then the equation of the cutting energy was set up as follows.
Cutting energy E=1/2I (ω2n2-ω22)
I; Moment of inertia of the shaft with rotary knife
ω2n; Angular velocity in case of no load
ω2; Angular velocity after cutting
The results of experiments are summarized as follows.
1) Analyzing the variance of the results of experiments, the significant difference at 1 percent level was recognized in the bevel angle of knife, the cutting speed and the diameter pasture stalk.
2) The relation between the bevel angle and the cutting energy became a cubic function. As the bevel angle became smaller than 23deg., the cutting energy decreased rapidly. As the angle became bigger than 45deg., the cutting energy increased rapidly.
3) The relation between the cutting speed and the cutting energy became the quadratic function. As the cutting speed became faster than about 40m/s, or slower than about 20m/s, the cutting energy increased. When the bevel angle was large, or stalk was thick, this relation became more clearly.
4) The relation between the diameter of stalk and the cutting energy became a linear function. As the cutting speed was rather slow the effect of stalk diameter on the cutting energy was remarkable.
