Core Drilling Equipment Core Drilling Rig
1. Which types of core drilling rigs are used for surface core drilling?
* Modified underground core drills
* Specialized surface core drills
2. Which are the main components of a surface core drilling rig?
* Drill mast
* Rotation head
* Rod holder
* Main hoist
* WL winch
* Frame with bracket for the drill mast
* Mast dump cylinder
* Control panel
* Hydraulic system
* Power unit
* Carrier
* The following accessories are normally available as optional extra:
- Rod handling arm
- Mast mounted platform for the helper
- Flush pump and/or mud pump
- Mud mixer
- Mud tank
3. What is the main difference between a rotation unit for a typical underground core drilling rig as compared to a rotation unit designed for a surface core drilling rig?
* On a specialized surface core drill the rotation head includes a hydraulic motor that transfers the RPM and the torque to the hydraulic chuck via four or five speed gear box and a hollow spindle. Thanks to the gearbox there are four or five speed/torque ranges available to the driller.
* The spindle speed is normally infinitely variable within all these ranges. The low speed range has a high max torque which makes it suitable for drilling with casing or roller bits in overburden formations.
* The high speed range, which has a low but sufficient torque, is intended for core drilling in hard solid formations. The middle ranges have speed/torque combinations suitable for deep angled holes with large dimensions.
4. There are two different rod handling systems used for surface core drilling. Describe these two systems.
* There are two types of rod handling systems used on surface core drilling
machines. It is either the same type as on the under ground core drills or a special systems used on surface core drill only.
* The “underground” system can only be used when drilling with B size systems and perhaps also when drilling with N size systems provided the drill string is broken down in 3 meter drill rod lengths. In any other case the drill rods are too heavy and some kind of device is needed to lift the drill rod from the feed frame to the rod rack.
* When running the drill rod string out of the hole it is an advantage to break down the string in as long drill rod lengths as possible. The rod running time will be much shorter if you can break down a 450 meter drill string in 50 x 9 meter lengths instead of 150 x 3 meter lengths. When drilling under ground there are seldom room for longer drill rod lengths than 3 meters. In surface drilling there are no restrictions as regard the space it is more a matter of how long drill rod lengths that can be handled by the drilling crew and the drill rig. The drill rods are heavy a 6 meter long N wire line drill rod has a weight of approx. 45 kg and a corresponding H wire line drill rod has a weight of approx. 70 kg.
* The drill mast on a surface drill can either handle 6 meter or 9 meter drill rods lengths, depending on the size of the core drill. The drill rods them self are still 3 meter long but they are broken down in 6 or 9 meter drill rod lengths i.e. you only open each second or third threaded coupling. The drill string is hoisted out of the hole by means of the main hoist and a wire equipped with a hoisting swivel. The drill rod lengths are the stacked either vertically in the drill mast or horizontally on a rod rack or on a rod truck. The breaking of the threaded couplings are done by means of the rotation head and the rod holder. Unlike on an underground type of core drill these two components are not synchronized but the driller has to control the operation with two levers on the control panel.
* In order to stack the drill rod lengths vertically in the mast, it must be equipped with a platform in the top where a helper can stand and assist with the stacking and to uncouple the hoisting swivel. It is also possible to use a so called rod handling arm for moving the drill rod lengths from the feed frame to the drill mast.
5. Why should rod handling be avoided as much as ever possible?
* Rod running is a heavy, time consuming, unproductive and a not completely safe operation.
6. Describe some typical carriers for a surface drill rig.
* Tractors
* Trucks
* Crawlers
* Platforms
* Skid frames
Source: https://www.cgegtech.com/
Geo Equip Tech Wuxi, CGET Wuxi
*Without permission, it cannot be reproduced, and the source of the reprint must be indicated.*
