Operator’s instructions
7. Drilling
77
3. Move the drill bit forward until it is pressed against the rock.
4. Switch on high percussion pressure for several seconds.
5. Switch off percussion pressure when the drill bit has loosened. If the percussion
pressure is engaged for too long then the drill steel can detach from the shank
adapter.
6. Unscrew the old drill bit by hand and replace with a new one.
Action in case of drilling problems
Drilling problems
If the following trouble occurs during drilling:
•Hot coupling sleeves (loose coupling sleeves).
• Difficulties in uncoupling the coupling sleeves.
• Hole deflections
High coupling sleeve temperature
Note
Coupling sleeve temperature must not exceed 120 ºC (248 ºF).
1. Excessive coupling sleeve temperature is indicated by:
a. Measuring with a thermometer
b. Oil dripping from the rock drill vaporises on the coupling sleeve
c. The coupling sleeve changes colour
2. Depending on the layers of the rock, temperature can vary even within a small
area. High coupling sleeve temperature is usually due to a poor relationship
between drill feed pressure, percussion pressure and rotation pressure. The follow-
ing solutions are recommended to reduce coupling sleeve temperature.
a. Check the condition of the drill bit; an overdrilled bit gives less torque in the
coupling sleeve.
Grind the drill bit.
b. Change to a drill bit with ballistic buttons.
c. If the rock is too hard for ballistic bits, then...
To Next Page
Loading...
Need help?
General
