Operator Training - Drilling Principles India
Transcript of Operator Training - Drilling Principles India
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Operator training
Drilling principles
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Sandvik Mining and Construction
DRILLING PARAMETERS
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DRILLING PARAMETERS
What do we need for drilling?
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DRILLING PARAMETERS
What do we need for drilling?
PERCUSSION
FEED
ROTATION
FLUSHING
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DRILLING PARAMETERS
Percussion
Create the stress wave
Energy Piston RodShank
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Percussion
Piston velocity at impact : 10 m/s
Energy Piston Stress wave Rod
Stress wave (compressive force) accelerate to velocityof sound in steel, approx. 5140 m/second
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Percussion
The rock is crushed and the bit advances0,5 -1,0 mm
Piston Shank Rod
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Efficiency of the stress wave:
Energy transmission into the rock. This is governed by
the cross sectionnal area of the rod. the lenght of the stress wave (piston length). the rock penetration resistance of the bit (bit design and rock charasteristics). the weight of the bit.
DRILLING PARAMETERS
Percussion
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Percussion
DRILLING PARAMETERS
Controling the stress wave:The most critical issue in controlling the stress wave is toavoid tensile reflections waves.
The tensile stresses are directly responsible for prematurefailure due to fatigue.
The tensile stresses are transmitted through the coupling by
the thread surfaces. The Temperature of the shank is an indicator of tensile
stress
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Percussion
DRILLING PARAMETERS
Drilling into cavity will create extremely high tensile stresses
Drilling with underfeed (or poor flushing) will lead to a initial gap between thebit and the rock. In the beginning of the bit indentation the situationresembles the previous case.
Drilling with too low penetration resistance is close to the underfeedsituation (but with lower tensile amplitude). On the other hand tensilestresses will take place consistentently, not occasionally as with underfeed.
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Percussion
DRILLING PARAMETERS
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DRILLING PARAMETERS
Percussion
Too high: short steel lifeToo low: poor penetration
Lower pressure needed when:
- collaring
- uncoupling
- hitting fractured and layered rock
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DRILLING PARAMETERS
What do we need for drilling?
PERCUSSION
FEED
ROTATION
FLUSHING
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DRILLING PARAMETERS
Used for keep the bitin contact with therock
Feed
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DRILLING PARAMETERS
Under feeding
Feed
Video
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DRILLING PARAMETERS
Feed
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DRILLING PARAMETERS
Feed
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DRILLING PARAMETERS
PERCUSSION
FEED
ROTATION
FLUSHING
What do we need for drilling?
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DRILLING PARAMETERS
GOOD RPM
For create an indexingdistance between twopercussion impacts
Rotation
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DRILLING PARAMETERS
RPM TOO HIGH RPM TOO SLOW
Rotation
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DRILLING PARAMETERS
Rotation
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DRILLING PARAMETERS
How to check if the RPM is correct practicaly?
Rotation
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DRILLING PARAMETERS
PERCUSSION
FEED
ROTATION
FLUSHING
What do we need for drilling?
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DRILLING PARAMETERS
Flushing
Removal of cuttings:
Water, Air or Foam
Space between hole and rod:
Important for bailing velocity
Insufficient flushing:
reduced penetration rate
risk of jamming
Excessive wear of the rock tools