抄録
We studied the effects of the sharpness of blades, the cutting characters of the particular rotary tines, and considered about the arrangement of rotary tines.
The principal results obtained from these studies are as follows:
1) When the soil moisture content is much, the difference of the cutting resistance according to the sharpness of the blades is not considerable, but it increases as moisture content decreases. Since the dull blade acts disadvantageously not only to the power required but the strength of the blade, it must be kept sharp.
2) To make the load of each blade as equal as possible, arrangement and hitting order of the tines were considered under various conditions. Assuming that the hitting order of the left ended blade is No. 1, the order of the next blades respectively is No. (1+C), No. (1+2C), …….
But the constant number C does not take any odd numbers and the measures except 2.
3) It is of great advantage to make the width of a blade greater on the power required. But considering the variation of torque and other things, it must be prepared to keep two or three tines at least are in the cutting process.
4) It is advantageous to make length of the edge of the vertical blade as short as possible. But the curved part of the horizontal blade should be more smooth and the length of the blade must be determined according to the total number of blades which is relating to 3).
5) The lower the revolution of the rotary shaft is, the less the power required. While the dropping of the number of revolution of the rotary shaft is limited by the size of the clods, the revolution must be determined by the point of view of keeping the desirable tillage depth rather than size of the clods.
6) The total power required reduces as the cutting width of a blade increases and the number of tines decreases. But the power does not reduce too much over about 100mm with the model blades experimented (1/2 scale of practical blades).
