Matriz De Riesgos De Un Taller Mecanico

A–Z
OF DRILLING

halcorocktools.com
1

CONTENTS

INTRODUCTION

INTRODUCTION

2

COMPRESSED AIR

17

APPLICATIONS

3

EQUIPMENT SELECTION

27

ADVANTAGES AND
COMPARATIVE COSTS

4

OPERATING DTH EQUIPMENT

37

5

TROUBLESHOOTING

55

6

DRILL BIT CARE

63

7

2

3

HAMMER AND DRILL BIT
DEVELOPMENT

1

APPENDICES

73

3

HAMMERDEVELOPMENT
The Down-the-hole or DTH hammer is
used for drilling holes through a wide
range of rocks and associated materials
and the variety of applications to which it
can be put has extended and continues
to extend well beyond the original
conception of primary blast hole drilling.
Andre Stenuick of Stenuick Freres
Belgium was first to start commercialising
the product in 1950.
Halco inclose co-operation with Stenuick
Freres actually pioneered the development
and distribution of the down-the-hole
hammer, primarily throughout the UK,
Australia, New Zealand, Africa and India in
the 1950’s.
Prior to their introduction in the early
1950’s blast hole drilling was normally
carried out with drifter equipment whilst
water well drilling in hard formations was
done by cabletool rigs or rotary rigs using
rock roller bits (Tricones).
However, because drifter drilling becomes
progressively slower with increasing
depth, unlike DTH hammers, and because
the latter can drill in one day what a cable
tool rig takes weeks to complete, the
quarrying, water well, site investigation,
civil engineering and mining industries
throughout the world have become more
and moreaware of the advantages to be
gained from using DTH hammers, not only
as an alternative to drifters but because of
the higher performances when compared
to conventional rotary drilling.

The DTH hammer concept proved so
popular that established manufacturers
of drifter steels, bits and accessories,
followed Halco’s lead and developed their
own range of DTH hammers and bits.

Modernhammers are generally valveless
in design with fewer internal parts
requiring little maintenance. The removal
of the valve has eliminated the operational
problems previously experienced.

“Down the hole” refers to where the
hammer action occurs when compared to
drifter hammers, which hammer on top of
the drill string. The DTH hammer piston
always makes direct contact with the drill
bitand there is generally no loss
of transmitted energy as the hammer drills
deeper, as is the case with drifter
(top hammer) rigs.

Modern hammers are also of a rigid
construction enabling them to withstand
air pressures as high as 28 bar (400 psi).

Penetration rates with DTH hammers are
almost directly proportional to air pressure
therefore doubling the air pressure,
will result inapproximately double the
penetration.

Increases in penetration rates will
require the investigation of delivering yet
higher air pressures to the hammer as
in conventional designs, or the use of
alternative power sources such as water
or oil.

The first ever hammers were of “valved”
design. and had an internal liner. This
valved technology, together with,
compressor availability limitedthe air
pressure capability of the early hammers
which were incapable of withstanding air
pressures above 12 bar (170 psi).
The valve itself had operational problems
because hammer malfunction occurred
when large volumes of water were passed
through the hammers or if grit entered the
hammer.

Valved Hammer

Valve
Valveless
Hammer

4

The further development of DTH hammers
willbe in terms of their design related to
achieving lower drilling costs for the user
by increasing rates of penetration with
longer life in the hole.

To achieve longer life of the components
of the hammer, research of wear and
impact resistant materials not normally
associated with traditional hammer
manufacture, will be essential.
Water powered hammers are being
developed for use in...