Excessive rotational speed or drill feed
will cause the cutting forces acting upon the drill to be greater than they should be.
When rotated at a high speed and pressed with high axial force into sheet metal or thin walled tube, generated heat softens the metal and lets the drill feed
forward, produce a hole, and form a bushing from the displaced material.
In drilling, this problem can be caused by using the wrong type of drill or a dull or incorrectly sharpened drill, or by an excessively light or slow drill feed
, among other factors.
The hydraulic system for operating drill feed
is self-contained and includes an oil reservoir.
To improve visibility from the operator station, the drill feed
has been mounted sideways on the boom.
Difficulties were experienced in holding the vehicle steady at the ice face and controlling the drill feed
The rigs are equipped with Sandvik's RD314 high-frequency rock drill, while their telescopic drill feed
offers versatility for development, bolting or short-hole production drilling.
As well as conventional bolting positions in arch-section and rectangular roadways, the drill feed
can also move to any conceivable drilling angle in the drivage direction, as may be required for exploration and reinforcement work or additional blasting.
Changing from AISI/SAE low carbon mild steel at 20,000 psi tensile to stainless in the 70,000 to 120,000 psi range, alloy steels such as 4130 with 70,000 to 200,000 psi, or titanium alloys with 130,000 to 190,000 psi tensile, drill feed
thrust increases almost directly by this tensile difference.
The drill feed
has a centralizer which collects and directs the drill cuttings to the mine floor.
Positioning speed of 98 ft/min coupled with the two-speed spindle motor and 12"/min variable drill feed
rate assure fast, accurate hole making.
A double rotation device allows the operator to position the drill feed
vertically on both sides and close to the side walls.