QUALITY BUTTON BITS Drilling Equipment They can be Hydraulic or - - PowerPoint PPT Presentation

PERCUSSION DRILLING AND QUALITY BUTTON BITS

Crawler (Surface) Jumbo (Underground)

Drilling Equipment

 They can be Hydraulic

• r 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 Model DS Model

ABC of Robit S Model A Model M 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

• f 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?

?

BUTTON BIT SELECTION

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.

BUTTON BIT SELECTION

WHAT’S IMPORTANT?

SOME RULES OF THUMB

BUTTON BIT SELECTION

 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 Coupling Coupling Extension round drill rod Extension round drill rod Coupling Coupling 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 Rods

Used 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 Carburization Inner 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 thread

C 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 Coupling

Used 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

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 Coupling

Used 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 holes Splines

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 Components

L : 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

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