回転-打撃穿孔に関する基礎研究 (第3報)

抄録

The effects of thrust, perccussion, rotation of bit and interval of blow on rotary-percussive drilling mechanism are descrived in this paper.
Sample is put on the drop test apparatus under certain prestress. After the blow is made by dropping weight, penetration of bit and cross-section of crator is measured and then bit is rotated 180 degree. From the above mentioned experiments, the following results are obtained.
1) Penetration of bit is proportional to the prestress, but percussion affects penetration much more than prestress in this case.Also, mixed action of thrust and percussion is observed as shown in Fig.4.
2) Shape of the cross section of crator is getting sharp with increasing thrust.
3) Volume of the crator is growing with increasing blow energy.
4) The role of thrust is very important in rotating the bit.Namely, when the bit is rotated with overbalanced thrust, the cutting depth is increased linerly with penetration of bit to the sample.
5) When the bit is continuously rotated several rounds statisticaly, penetration rate per round is increased with the increasing thrust and blow energy, but is decreased when the interval of blow is prolonged.
6) Rotation torque has maximum value when the bit is rotated 360.degree under certain thrust and blow.
7) Energy consumption is getting much more linerly with increasing thrust, but when the interval of blow is prolonged, energy consumption is decreased.