Dth Setup; Makeup Torque And Backhead Closure; Drill Lubrication; Lubrication Guidelines And Specifications - Atlas Copco Secoroc QLX Series Operator Instructions Manual

DTH HAMMER SETUP
For higher air flow, the Airselect guide is adjusted to uncover
holes closer to the end of the guide. This delays the closure
of the valve until the piston has travelled further down. The
additional 'swept volume´ allows more air to flow into the drive
chamber of the hammer, extracting the power of the available air
for drilling instead of wasting it by dumping it to exhaust. Since
the additional air flows through the operating chambers of the
DTH hammer, power-robbing back pressure is also avoided.
Airselect is available in QLX 50/55 and QLX 60/65. This
innovation allows the Airselect setting to be changed simply by
rotating the guide with a hex socket wrench. Using extensions,
the Airselect can be reset from the chuck end of the hammer
without disassembly.
Note: QLX hammers with Airselect are shipped from the factory
at position 2.
When adjusting the Airselect system, be sure the socket is
securely attached to the extension. A few wraps of electrical
or similar tape will help secure the socket to the extension. If
the socket detaches from the extension, it will be necessary to
disassemble the hammer and retrieve it before drilling. For best
results, attach the socket permanently to the extension.
SOCKET
QLX 50/55 7/16''
QLX 60/65 9/16''

Makeup torque and backhead closure

The QLX drills use a ´compression cone´ arrangement
whereby parts are held in place under very high load.
Because of the high load used to clamp the parts in place in the
QLX drills; a high level of torque is needed to close the backhead
gap. Rotary head torque may be sufficient but in some cases a
supplementary wrench may be needed. It is extremely important
that the backhead gap be closed in these drills.
The presence of a gap between the casing and the back-head
while drilling will increase the chances for loosening the
backhead in the hole and possibly losing the drill.
In addition to at least closing the backhead gap, it is also
suggested that the backhead and chuck be torqued to
approximately 750 - 1000 ft.-lb per inch (40.5 - 54 N-m per
mm) of hammer diameter. For example a 6 in. (152 mm) class
(QLX 60) drill should be torqued to 4500-6000 ft.lb (6156-
8208 Nm). This makeup torque insures against loosening joints
in the hole and also preloads the threads sufficiently.

DRILL LUBRICATION

Lubrication guidelines and specifications

All DTH hammers require oil lubrication to resist wear, galling
and corrosion. Additionally, the film of oil coating all internal
parts seals internal clearance paths to reduce power-robbing
leakage across sealing clearances. As a general rule of thumb the
oil required is proportional to the volume of air being used.
Oil also needs to be of sufficiently high quality. It is recommend-
ed that Atlas Copco Rock Drill Oil be used. If another type of oil
is used it must comply with the oil specifications shown on page
20.
8
EXT. LENGTH
24''/610mm
24''/610mm
For dry drilling (less than 2 gpm (7.6 lpm) of water injection) it
is generally recommended that oil be injected into the drill air
stream at the rate of 1/3 pint (.16 l) of oil per hour for every 100
scfm (2.8 m 3 /min.) of air. For example a 900 scfm (25.5 m 3 /min.)
compressor delivering full flow to a DTH hammer would require
900 ÷ 100 x 1/3 = 3 pints per hour (25.5 ÷ 2.8 x .16 = 1.6 l per
hour). For wet drilling (more than 2 gpm (7.6 lpm) it is suggested
that the lubrication rate be doubled to 2/3 pint (.32 l) of oil per
hour for every 100 scfm (2.8 m 3 /min.) of air. The additional oil
compensates for the wash-out caused by water and the oil
losses. Additional lubrication is also required when drilling with
soap or foam. See the 'Drilling With Foam´ section for more
details (refer to chart below).
OIL INJECTION RATE pints/hr (l/hr)
AIR FLOW DRY DRILLING
scfm
150 0.5 (.2)
250 0.8 (.4)
350 1.2 (.6)
500 1.7 (.8)
600 2.0 (1.0)
750 2.5 (1.2)
800 2.7 (1.3)
900 3.0 (1.4)
1050 3.5 (1.7)
1250 4.2 (2.0)
1500 5.0 (2.4)
2000 6.7 (3.2)
3000 10.0 (4.7)

Lubricators

There are two primary types of lubricators; a plunger oiler and a
venturi oiler.
A plunger oiler normally operates from a timed plunger system
which delivers a fixed ´slug´ of oil into the line in timed intervals.
These systems are beneficial in that the oil reservoir does not
need to contain a high pressure. Plunger lubricators are also
insensitive to oil viscosity and temperature. However, because
of their complexity, the reliability of plunger lubricators is not as
good as the venturi type. Also, because oil is delivered as ´slugs´
it is not atomized and delivered to the drill internals as evenly as
a venturi.
Venturi type lubricators (sometimes referred to as pig oilers)
operate in a similar fashion to a gasoline carburetor. A necked
down area in the venturi creates a pressure drop which draws
oil into the air stream. The oil is atomized and mixed very
efficiently with the air providing maximum coverage and
cohesion to internal drill components. A needle valve is usually
used to adjust the oil volume delivered. Disadvantages of the
venturi oiler are that it requires a pressurized reservoir, which is
generally small in volume. Also, the lubrication rate is dependent
on oil viscosity which varies with temperature.

Lubrication check

When oil is injected into an air stream with dry piping or hoses
it takes a considerable amount of time to coat the walls of the
piping so that the oil is actually delivered to the DTH hammer.
Until these surfaces are coated with an oil film very little is
actually delivered to the DTH hammer. It´s important to insure
that an oil film is established before starting the DTH hammer.
It´s recommended that the drill be allowed to blow until a visible
film of oil is developed on the bit blow hole.
Placing a piece of cardboard or wood beneath the blow holes
gives a good indication when oil is passing through the drill.
WET OR HYDROCYCLONE
DRILLING
1.0 (.5)
1.7 (.8)
2.3 (1.1)
3.3 (1.6)
4.0 (1.9)
5.0 (2.4)
5.3 (2.5)
6.0 (2.8)
7.0 (3.3)
8.3 (3.9)
10.0 (4.7)
13.3 (6.3)
20.0 (9.5)