percussion drilling and quality button bits...percussion drilling impact or percussion created by...

PERCUSSION DRILLING

AND

QUALITY BUTTON BITS

Crawler (Surface)

Jumbo (Underground)

Drilling Equipment

They can be Hydraulic

or Pneumatic

Drilling Tools

PRINCIPLES OF PERCUSSION DRILLING

ROTATION

FEED FORCE

FLUSHING

IMPACT

POWER

PERCUSSION DRILLING

Impact or percussion created by

the rock drill piston is transmitted to

the rock through the drill string. The

rock is broken in a crushing affect,

in front of the buttons.

Feed force is required to keep

the drill string in contact with the

rock drill and the bit in contact with

the rock.

Rotation is required to index the bit between consecutive blows.

After each blow, the bit must be turned to ensure there is always

fresh rock under the buttons.

Flushing is used to remove the rock cuttings from the hole and

to cool the bit.

ROCK BREAKING

IMPACT FORCE

CRUSHED ZONE

FRACTURED ZONE

ELASTIC ZONE

FREE SURFACE

What happens

in the hole?

Drilling With Robit

Robit is a Finnish manufacturer of high constant

quality top hammer products for rock drilling and

casing systems for ground drilling.

ABC of Robit

A Model B ModelDS Model

ABC of Robit

S Model A ModelM Model

ABC of Robit

Retrac Normal

BUTTONS

spherical ballistic

ABC of Robit

impact force the harder the rock the more impact force is needed

feed force should increase with the impact force

impact frequency

rotation speed linked with the frequency and bit diameter

flushing volume as much as possible

DRILLING PARAMETERS

For the best performance, these parameters are to be

adjusted or set in relation to each other… to match the

rock conditions.

(WHICH AFFECT PERFORMANCE)

DRILLING PARAMETERS – Formulas and tips

Rotation speed

Normally, the driller would first set the impact force depending on

the rock, then the rotation speed. After that the feed until he gets a

smooth rotation.

If drilling parameters are correct:

Optimum lifetime of drill string and rig

Temperature of the shanks (just after drilling) should be 60-70

degrees with air flushing and about 40 degrees with water

flushing

Cuttings should be size of chips; the bigger the better

WHAT MAKES A HIGH QUALITY BIT

PROPER DESIGN

- flushing properties

- button layout, diameters, quantity

- materials used

QUALITY MATERIALS

- buttons and bodies

- proper balance: hardness / strength

MANUFACTURING ACCURACY

- precision machining & measuring

- uniform tempering

- consistent quality & control

ROBIT DESIGN

Designs are adjusted to match different

applications and conditions.

Different configurations are available.

face and body shapes (and lengths)

flushing holes: size, quantity and locations

buttons: shape, size, quantity and locations

Bits are first tested in a 3D environment to

ensure strength, choose button and flushing

hole placement.

The flushing properties are analyzed.

Materials are decided depending on application.

Designs are adjusted based on actual results

and customer feedback.Robit listens to the customer.

• The Green Steel

– 100 % recyclable

– 80% less CO2 emissions

– Energy consumption minimized

– Improved fatigue strength

ROBIT MANUFACTURING

ROBIT MANUFACTURING

The bit bodies are initially

formed with state of the art

robotized machining. The

faces & bodies are shaped,

threads are cut and the

flushing grooves & holes

are bored.

This robotized machining is highly accurate and cost effective.

Robit uses a fluidized bed

heat treatment process for

better quality & control when

tempering the bodies.

The bodies are immersed in

an aluminum oxide sandlike

material with nitrogen gas

bubbling through.

This process maintains the

same even temperature

throughout the bodies so

there is no distortion of

dimensions.

Bodies get an extra surface

hardening with a sandblast

finish; this also eliminates

an extra process.

This method is environmentally clean, cost

effective and unique to Robit.

ROBIT MANUFACTURING

ROBIT MANUFACTURING

The button holes are

machined with state

of the art robotized

machines.

Each button hole is measured to an

accuracy tolerance of 0.001 mm

ROBIT MANUFACTURING

Robit measures each hole

(within 0.001 mm) and the

button insert is selected to

match.

A copper shim is inserted in

the bottom of each button

hole for an exact match with

shape and to ensure equal

load bearing throughout.

This material also acts as a

dampener.

Bodies are preheated before

the buttons are installed.The installation and fit of the button inserts

is a key factor in a quality bit.

BUTTON BIT SELECTION – Diameter and thread

• Diameter:

• Normally given by customer

• Depending on the application, rock, location and equipment

• Thread:

• Normally given by customer

• Most of them are standard

• R-type for Rope thread (R25, R28, R32, R35)

• C-type for Trapezoid type (C38, C45, C51, C58)

• T-thread at Sandvik; Fi-thread at AC; etc...

• Some are patented, but in some cases Robit found the way to have

equivalent:

• RG60-Type compatible with GT60 from Sandvik

• RR-Type compatible with SR-type from AC

There are different bit configurations available and consideration

should be given as to which ones are best for the application and

conditions.

BUTTON BIT SELECTION – Design, body, buttons

BUTTONS

spherical ballistic

FACES

some types of the many available

BODIES

normal retrac

There are three basic questions to determine the type of bit

selection:

BUTTON BIT SELECTION

1. How Hard is the Rock?

2. How Abrasive is the Rock?

3. How Homogeneous is the

Rock?

?


Hard Rock use bits with a large quantity of smaller button

use standard spherical buttons

Soft Rock use semi ballistic shaped buttons

considerations are abrasiveness and

homogeneousness

Abrasive Rock use bits with large diameter gauge buttons

Non Abrasive considerations are hardness and

homogeneousness

Homogeneous considerations are hardness and abrasiveness

semi ballistic shaped buttons can be used

Non Homogeneous

use flat face bits with standard spherical buttons

use retrac bodies and side flushing holes

Different types and configurations are available, each with

specific characteristics designed to best meet certain criteria

and under certain rock conditions.

As examples: a bit can be designed for fast penetration in hard

rock or for reduced deviation in broken rock or for longer life,

etc... but normally when gaining in one criterion, there is a

loss in another.

In other words, it is not possible to have a button bit designed

and built to be good at everything; it is a selection of what is

important, then compromising to some extent on the other

criteria.


WHAT’S IMPORTANT?

SOME RULES OF THUMB


A bit with smaller buttons will penetrate easier and faster than a

bit with bigger buttons but smaller buttons wear more rapidly.

A bit with ballistic buttons will penetrate well in softer conditions

but in broken rock, the ballistic buttons tend to break easier.

A drop center faced bit will usually drill straighter than a flat

faced bit but a flat face bit will last longer.

A bit with a retrac body will increase hole straightness and it

helps avoid getting stuck in layers of broken rock.

In all conditions it is important to have sufficient flushing,

enough to clear the fresh cuttings away from the face of the bit

as this helps reduce wear and maintains hole quality.

Quarrying

Construction

Mining

Threaded button bits applications

• Robit codes:

Robit product description - Bits

HTG 51C 102 D R Ball

Buttons type Ball = Ballistic

Nothing = Round

Body type R = Retrac

Nothing = straight

Face design

Diameter

Thread

Series HTG= Hard Top Green

Rock Drilling Tools Components

Surface drilling

Shank adapter

Extension hexagon

drill rod

Extension hexagon

drill rod

CouplingCoupling

Extension round

drill rod

Extension round

drill rod

CouplingCoupling

Extension male/female

hexagon drill rod

Extension male/female

hexagon drill rod

Extension male/female round

drill rod

Extension male/female round

drill rod

Button bit

Retrac bit

Rock Drilling Tools Components

Tunneling & drifting

Shank adapter

Drill rod

Hexacon/round

Coupling

Threaded

button bit

Coupling

Drill rod

Hexacon/round

Pilot

adapter/reamer

Threaded

blade bit

Tapered

button bit

Tapered

blade bit

Rod

Rod Components

Female End Male End

Round Rods

Used in extension drilling for production

Heat treatment : High Frequency induction

Hexagonal RodsUsed in tunneling drilling for blast holes

It measures from the flat to cross sectional dimension

Compare to round Rods,

Rigid, Heavier and better transfer energy, flushing better

Hexagon rods

Round Rod

D

D

Rod

Heat Treatment

Carburization

Entire rod is hardened providing a case over the entire rod surface both internal and external

Used in underground drilling with the using water flushing.

Example) Drifter Rods(Hexagonal rods)

H/F induction(high frequency) hardening

Only the thread ends are hardened

Used in surface drilling when using air flushing

Ex) Extension Rods(round or Somtimes Hexagonal rods)

Outer Core

CarburizationInner Core

Carburization

Hexagon Rod

Rod

Extension Rods(M/M)

With the longer rods tending to be larger diameter.(C38-3050mm, C45-3660mm)

Normal extension rods have a feature having same size of thread on each end of the rods.

Mostly round rods are more common

Tunneling Rods(M/M)Because the coupling does not go inside the hole, a bit diameter closer to the rods dimension can be

used.

Drill rod is available in many standard lengths to match the drill feeds on a multitude of available drifting

jumbos. The rods have a feature by different size of thread on each end of the rods

Mostly hexagonal rods are more common in tunneling with Jumbo Drill Rig.

Rods

Male/Female (M/F) Rods

The female part of the thread is integrated with

special method called ”friction welding”

It means no need to use coupling at female end.

M/F rods drill rod provides more rigid connection

and is easier to uncouple and handle.

The life time is also better than using M/M rods as

well.

Main advantages of M/F are :

Easy handling, quicker uncoupling,

tighter connection and straighter holes.

”Better Energy delivery”

REDUCED TRANSMITTED ENERGY LOSS

10%

3%

5%

Note:

M/M connection as found in conventional

coupling can lose 6-10% of the energy

transmitted though the two joint

M/F coupling only lose 3-5% of the energy

transmitted

Threads

Rope Thread (R thread)

Rope thread have a low pitch, 12.7mm and a

small angle of profile

Adv. Dis adv.

”Good wear resistance” ”not easy to uncouple”

Application

Single pass or shorthole drilling such as

undergound that need to infrequent uncoulpling

C threadC thread or ”T and HM” have same pitch and a

larger angle of profile than R thread

Excellent wear properties and easy to couple

It is very good to use extension drilling with

several rods.

“Especially with high powered drills we recommend requested our C thread”

Couplings

Semi-Bridge Coupling

Semi-Bridge couplings are most suited to high

torgue machne with C thread

Full-Bridge Coupling

Normally used in surface drilling

Better uncoupling and provide tight joints.

Not possible to misuse

Adapter CouplingUsed when changing from one thread type , or size, to

another and are typiclly required only in special

circumstances

It means this can allow rods to use different thread had

Shanks

Flushing

holesSplines

The shanks for hydraulic drills and some pneumatic drills have external or front head

flushing. Hydraulic shanks generally have at least 5 to 14 spline configuration.

Pneumatic shanks tend to have internal or through flushing and can generally be

identified by 4 spline configuration

Defining ComponentsL : Length of Shank

D1 : Thread Diameter

D : Barrel Diameter

D1

Sell the difference!

Why Robit products?

High quality product

Competitive price price per driller meter!

Service Technical support; stock; warranty...

Customer feedback taken into consideration

Robit family spirit

THANK YOU !

percussion drilling and quality button bits...percussion drilling impact or percussion created by...

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