ロッドジョイントにおける彈性波の反射について
1958 年 74 巻 835 号 p. 7-12
詳細
1958 年 74 巻 835 号 p. 7-12
On the drilling mechanism of rock with long rod, previously reported, it was proved that the drilling efficiency results not from the increase of rod length, but from the decrease of output of rock drill and the cuttings. Later results of the drilling tests with joint rod proved that the reflection energy at joint had an important effect upon the drilling efficiency. So we investigated on the reflection energy with various type of joints.
The results obtained are as follows:
(1) Even at the jointless rod (5m), energy loss was 10% per cycle of the elastic wave.
(2) The total energy loss of taper joint rod (5m) per cycle was 15%, buttress joint was 17 % and upset joint was 37%.(3) The reflection energy of taper joint was 4.0%, buttress joint was 3.0% and upset joint was 2.0%.(4) The friction loss of taper joint was 3.5%, buttress joint was 5.5% and upset joint was 16.5%.(5) The joint contactivity Cj was given by
Cj=H-H'/H
where H is impact energy, and H' is reflection energy loss.
