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

PERCUSSION DRILLING AND QUALITY BUTTON BITS

Drilling Equipment  They can be Hydraulic or Pneumatic Crawler (Surface) Jumbo (Underground)

Drilling Tools

PRINCIPLES OF PERCUSSION DRILLING IMPACT POWER FEED FORCE FLUSHING ROTATION

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 FREE SURFACE What happens FRACTURED ZONE in the hole? ELASTIC ZONE

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 DS Model B Model

ABC of Robit S Model M Model A Model

ABC of Robit BUTTONS spherical ballistic Retrac Normal

ABC of Robit

DRILLING PARAMETERS (WHICH AFFECT PERFORMANCE)  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 For the best performance, these parameters are to be adjusted or set in relation to each other… to match the rock conditions.

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 Robit listens to the customer. and customer feedback.

ROBIT MANUFACTURING • The Green Steel – 100 % recyclable – 80% less CO2 emissions – Energy consumption minimized – Improved fatigue strength

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 MANUFACTURING 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. This method is environmentally clean, cost Bodies get an extra surface effective and unique to Robit. hardening with a sandblast finish; this also eliminates an extra process.

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

BUTTON BIT SELECTION – Design, body, buttons There are different bit configurations available and consideration should be given as to which ones are best for the application and conditions. BODIES BUTTONS spherical ballistic normal retrac FACES some types of the many available

BUTTON BIT SELECTION There are three basic questions to determine the type of bit selection: 1 . How Hard is the Rock? ? 2 . How Abrasive is the Rock? 3 . How Homogeneous is the Rock?

BUTTON BIT SELECTION  use bits with a large quantity of smaller button Hard Rock  use standard spherical buttons  use semi ballistic shaped buttons Soft Rock  considerations are abrasiveness and homogeneousness  use bits with large diameter gauge buttons Abrasive Rock  considerations are hardness and Non Abrasive homogeneousness  considerations are hardness and abrasiveness Homogeneous  semi ballistic shaped buttons can be used Non Homogeneous  use flat face bits with standard spherical buttons  use retrac bodies and side flushing holes

BUTTON BIT SELECTION 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?

BUTTON BIT SELECTION 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.

Threaded button bits applications Mining Quarrying Construction

Robit product description - Bits • Robit codes: HTG 51C 102 D R Ball  Ball = Ballistic Buttons type  Nothing = Round  R = Retrac Body type  Nothing = straight Face design Diameter Thread Series  HTG= Hard Top Green

Rock Drilling Tools Components Surface drilling Shank adapter Coupling Extension hexagon Coupling Extension hexagon drill rod drill rod Coupling Extension round Coupling Extension round Button bit drill rod drill rod Extension male/female Extension male/female Retrac bit hexagon drill rod hexagon drill rod Extension male/female round Extension male/female round drill rod drill rod

Rock Drilling Tools Components Tunneling & drifting Shank adapter Tapered button bit Coupling Drill rod Pilot Hexacon/round adapter/reamer Tapered blade bit Threaded button bit Coupling Drill rod Hexacon/round Threaded blade bit

Rod Rod Components Female End Male End D Round Rods Used in extension drilling for production Heat treatment : High Frequency induction Round Rod 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 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 Outer Core Inner Core Only the thread ends are hardened Carburization Carburization Used in surface drilling when using air flushing Ex) Extension Rods(round or Somtimes Hexagonal rods) Hexagon Rod