EFFECTS OF ROCK DRILLS ON OPERATORS

PART 1. VIBRATION OF ROCK DRILLS AND AIR TEMPERATURE AT PITS

Abstract

Vibration and coldness are the causes producing the lesions due to vibratory tool work. This paper describes the results obtained from measurements of the vibration acceleration of rock drills under the various conditions and the results obtained from measurements of air temperatures at 35 pits in a certain metal mine.
The rock drills had remarkably great vibration : according to the author's measure-ments, the greatest vibration was found in the sinker-type drill, the second in the stopper and the third in the leg-type drill with or without vibration-proof handle. The vibration of the drill in digging the hard rock was greater than that in digging the soft rock. The vibration in the initial cutting was less than that in the drilling operation.
Measurements of the vibration acceleration transmitted to the body when the drill was used revealed that both hands were exposed to the vibration of almost similar intensity, and the vibration transmitted to the body tended to decrease gradually from the hand to the central region.
The measurements of air temperatures at 35 pits which were selected at random in this mine were made on February, April, April, May, August, October and December. The mean temperature was 13.5 ± 2.4°C in August, while 6.0 ± 3.7°C in February. In summer there was little difference among the temperatures of pits but in winter a little.