Drilling with high rpm compared to drilling with conventional speed

IACDS Bauma 2013 seminar 2013-04-19
Possibility to adjust spindle speed in many steps to
avoid vibration.
Rigidity of complete drill system
Chatter and vibrations Biggest problem when:
• Drilling initial few centimeters into the concrete.
• Cutting through re-bars.
Wide speed range and many steps to choose from
a spindle speed can be chosen where vibration
is lower.
• Stiff and rigid drill rig.
Drill rig may not sway in any direction.
• Very important that base is properly secured.
• Bearing arrangement of the core drill
is critical. Very rigid, preferably
pre-loaded taper
roller bearings to eliminate vibrations.
• Carriage with low friction.
Bauma 2013
Munich seminar
Bauma 2013
Munich seminar
The drill bit is crucial for high rpm drilling
Sufficient cooling of drill bit
• There is no single ”universal” segment specification
that suits all machines and aggregates.
• Use of right drill bit specially developed for this
high speed drilling.
• Too soft bonds Diamonds are pushed in to
segment or fall out.
• Too hard bond Not enough diamonds will cut.
• Tool geometries must be suitable for high speed
drilling to minimize friction between barrel and
cored hole.
• As the concrete reduction rate
increases, the water flow must
be allowed to increase as well.
• Use of more water but during a
shorter time
No more cooling water totally.
Bauma 2013
Munich seminar
Bauma 2013
Munich seminar
4