The present disclosure relates to drill bits applicable in drilling operations. More particularly, the present disclosure relates to a flushing system in drill bits that facilitates better rate of penetration of the drill bit and also increases total lifespan of the drill bit.
Industrial drilling devices such as a “Down-The-Hole” (DTH) drill, have been typically employed in drilling relatively large diameter holes in surface-drilling applications. Heavy industries such as blast-hole mining, water well drilling, oil and gas, and construction work, employ the DTH drill for its ease of use and flexibility to drill aligned and accurately placed bore holes in a variety of rock conditions. A DTH drill, typically comprises a DTH hammer located directly behind a drill bit and drill pipes that transmit feed force and rotation to the DTH hammer and the drill bit. The drill pipes also supply compressed air or fluids for operating the DTH hammer and flushing of cut matter from the bore hole.
In recent times, the drill bit used in the DTH drill is provided with inserts (e.g., tungsten carbide inserts) on a cutting surface of the drill bit. The drill bit with the inserts is also commonly referred to as a button drill bit. The button drill bit also includes flushing holes to supply compressed air into the bore hole and facilitate removal of debris and/or cut matter from the bore hole to an outlet generally via an annular space around the drill bit.
Button drill bits with two flushing holes, for example, are known to endure excessive steel erosion on a cutting surface of the button drill bits as a result of the debris and/or the cut matter scraping against the cutting surface during operation. The excessive steel erosion causes the inserts to become exposed and weaken over time and thereby, reduces a total lifespan of the button drill bit. Button drill bits with two flushing holes are also known to have problems associated with poor air circulation around the cutting surface of the button drill bits and thereby, resulting in “secondary grinding” inside the bore hole. The secondary grinding refers to cutting of the already cut matter inside the bore hole as a result of the poor air circulation.
Button drill bits with three flushing holes, for example, have been used to provide better air circulation around the cutting surface of the button drill bits and thereby, achieve better flushing of debris and/or cut matter from the bore hole than the button drill bits with two flushing holes. However, the total surface area available for the inserts on the cutting surface of the button drill bits with the three flushing holes is comparatively lesser than total surface area available for the inserts on the cutting surface of the button drill bits with the two flushing holes. As a result, the button drill bits with the three flushing holes tend to have a lesser number of the inserts on the cutting surface in comparison with the button drill bits with the two flushing holes. The lesser number of inserts on the cutting surface of the button drill bits eventually reduces a rate of penetration of the button drill bits inside the bore hole and also reduces the total lifespan of the button drill bits.
U.S. Pat. No. 7,467,674 relates to a drill bit for a reverse circulation rock drill or down-the-hole hammer assembly. The drill bit includes inclined passages in the drill bit head and an axially extending central tube for recovery of drilling debris.
In an aspect of the disclosure, a drill bit comprising a body that is adapted to flush cut matter from a bore hole is disclosed. The body defines a flushing system that includes an inlet, a cutting surface provided with at least one main opening that is in communication with the inlet, and a peripheral surface, surrounding the cutting surface, provided with at least one secondary opening that is in communication with the inlet. The inlet facilitates supply of pressurized fluids to flush the cut matter from the bore hole. The main opening in the cutting surface allows passing of the pressurized fluids from the inlet to the bore hole and defines a main passageway originating from the inlet to the cutting surface. The secondary opening in the peripheral surface allows passing of the pressurized fluids from the inlet to the bore hole and defines a secondary passageway originating from the inlet to the peripheral surface. The secondary passageway is disposed at an angle with respect to a horizontal reference plane. The horizontal reference plane is defined between the inlet and the origin of the main passageway and is perpendicular to a central longitudinal axis of the body of the drill bit. The origin of the secondary passageway from the inlet is positioned at a distance from the horizontal reference plane.
In yet another aspect of the disclosure, a method for configuring a drill bit to flush cut matter from a bore hole is disclosed. The method includes providing an inlet in a body of the drill bit to facilitate supply of pressurized fluids to the bore hole. The method also includes providing at least one main opening in a cutting surface that is in communication with the inlet. The main opening provided in the cutting surface defines a main passageway originating from the inlet to the cutting surface. Further, the method includes providing at least one secondary opening in a peripheral surface surrounding the cutting surface that is in communication with the inlet. The secondary opening provided in the peripheral surface defines a secondary passageway originating from the inlet to the peripheral surface. The secondary passageway is disposed at an angle with respect to a horizontal reference plane. The horizontal reference plane is defined between the inlet and the origin of the main passageway and is perpendicular to a central longitudinal axis of the body of the drill bit. The origin of the secondary passageway from the inlet being positioned at a distance from the horizontal reference plane. Furthermore, the method includes determining a diameter of the drill bit, determining velocity of the pressurized fluids through the secondary opening, and determining a pressure differential between a pressure of the pressurized fluids air around the cutting face relative to a pressure of the pressurized fluids at the inlet. In addition, the method also includes reconfiguring the secondary opening based on the diameter of the drill bit, the velocity and the pressure differential determined.
Reference will now be made in detail to embodiments of the disclosure, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.
Referring to
The drill bit 100 defines a body 106 that is adapted to cut and drill through a work surface 104 and form a bore hole 102. The body 106 includes the inlet 108, two main openings 110, 110′, and two secondary openings 112, 112′. The inlet 108 facilitates supply of pressurized fluids into the bore hole 102 via the two main openings 110, 110′ and the two secondary openings 112, 112′ in order to flush cut matter from the bore hole 102. The pressurized fluids may be hydraulic fluids or compressed air having inherent velocity and pressure. During operation, the pressurized fluids may be continuously supplied at the inlet 108 and allowed to enter the bore hole 102 via the two main openings 110, 110′ and the two secondary openings 112, 112′. Pressure from the pressurized fluids exiting from the two main openings 110, 110′, and the two secondary openings 112, and 112′ forces freshly cut matter from a bottom of the bore hole 102 to pass through an annular space 114 around the drill bit 100 and exit through to an outlet 116 that is level with the work surface 104.
Referring to
The flushing system 200 further includes a cutting surface 206 that is provided with at least one main opening 208 (also see
The flushing system 200, in addition, includes a peripheral surface 212, surrounding the cutting surface 206, that is provided with at least one secondary opening 214. Although not limited, the peripheral surface 212 may be parallel to the central longitudinal axis 210 of the drill bit 100. The secondary opening 214 is in communication with the inlet 204 such that the secondary opening 214 also allows passing of the pressurized fluids from the inlet 204 to the bottom of the bore hole 102. The secondary opening 214 defines a secondary passageway 213′ originating from the inlet 204 to the peripheral surface 212. The secondary passageway 213′ is disposed at an angle 217 with respect to a horizontal reference plane 216. The angle 217 of the secondary passageway 213′ with respect to the horizontal reference plane 216 may range from 37 degrees to 43 degrees. The horizontal reference plane 216 is defined between the inlet 204 and the origin 221′ of the main passageway 207′ and is perpendicular to the central longitudinal axis 210 of the body 202. An intersection of the central longitudinal axis 210 and the horizontal reference plane 216 defines a reference point 220′. In some embodiments, the horizontal reference plane 216 may be defined at an outer neck surface 219 on the body 202 of the drill bit 100. The outer neck surface 219 may a flat circumferential surface that may be perpendicular to the central longitudinal axis 210 of the body 202 of the drill bit 100. In some embodiments, the horizontal reference plane 216 may also be define at the intersection of the central longitudinal axis 221 of the main passageway 207′ with the central longitudinal axis 210 of the body 202.
The angle 217 of the secondary passageway 213′ and a diameter of the secondary passageway 213′ may be determined by evaluating one or more factors. The factors include, but are not limited to, a diameter of the drill bit 100, velocity of the pressurized fluids passing through the secondary opening 214, and a pressure differential between pressure of the pressurized fluids measured at the inlet 204 and pressure of the pressurized fluids measured around the cutting surface 206 of the drill bit 100. For example, the angle 217 of the secondary passageway 213′ may need to be increased above 43 degrees and/or decreased below 37 degrees for different diameters of the drill bit 100. Further, the diameter of the secondary passageway 213′ may need to be altered in order to moderate the velocity of the pressurized fluids. Also, the diameter of the secondary passageway 213′ may need to be altered in order to moderate the pressure differential.
An intersection of a central longitudinal axis 215 of the secondary passageway 213′ with the central longitudinal axis 210 of the body 202 defines the origin 220″ of the secondary passageway 213′. The origin 220″ of the secondary passageway may be at a distance (see
In some embodiments, the cutting surface 206 of the drill bit 100 is provided with an additional main opening 208′ (see
The peripheral surface 212 may also be provided with an additional secondary opening 214′ (see
According to one aspect of the present disclosure, a position of the secondary opening 214 and/or the additional secondary opening 214′ on the peripheral surface 212 is determined by a position of the inserts 218 such that none of the inserts 218 are in direct communication with the pressurized fluids exiting from the secondary opening 214 and/or the additional secondary opening 214′. Accordingly, no insert 218 is positioned in a region 225 that is immediately in front of the secondary opening 214 and/or the additional secondary opening 214′.
Further to the embodiments disclosed herein, different variations and implementations of the two secondary openings 214, 214′ on the peripheral surface 212 may be contemplated. For example, the peripheral surface 212 may be provided with multiple secondary openings and hence, multiple secondary passageways disposed at different angles from the horizontal reference plane 216. Similarly, the cutting surface 206 may be provided with multiple main openings and hence, multiple main passageways disposed at different angles from the central longitudinal axis 210 of the drill bit 100. Positions of the inserts 218 may also be manipulated with respect to positions of the multiple secondary passageways such that none of the inserts 218 are provided in the region 225 immediately in front of the multiple secondary passageways respectively. Multiple secondary passageways with similar and/or dissimilar diameters may also be provided. In some embodiments, a total of circumferential areas of the two main openings 208, 208′ and circumferential areas of the two secondary openings 214, 214′ respectively may be equivalent to a total of circumferential areas of three main openings and no secondary opening respectively.
Referring to
During operation (see
Corresponding to the pressurized fluids exiting the two main openings 208, 208′ and the two secondary openings 214, 214′ as shown in
The secondary passageway 213′ and/or the additional secondary passageway 213″ in the drill bit 100 having the flushing system 200 of
For example, referring to
In another example, referring to
In yet another example, referring to
In another example, referring to
Accordingly, maintaining the angle of the secondary passageway 213′ and/or the additional secondary passageway 213″ at 43 degrees and the distance of the secondary passageway 213′ and/or the additional secondary passageway 213″ at 5 mm is empirically determined to improve an overall efficiency of the drill bit 100. The overall efficiency of the drill bit 100 may be defined by the rate of penetration of the drill bit 100 through the bore hole 102 and the total lifespan of the drill bit 100.
The drill bit 100 may also be configured by means of a method in a digital simulation environment. For example, referring to
The method also includes a step 242 of providing at least one secondary opening 214, in the peripheral surface 212 surrounding the cutting surface 206, that is in communication with the inlet 204. The secondary opening 214 defines the secondary passageway 213′ originating from the inlet 204 to the peripheral surface 212. The secondary passageway 213′ may also be disposed at the angle 217, 226, 230, 234 (see
In addition, the method includes a step 246 of determining a diameter of the drill bit 100, a step 248 of determining a velocity of the pressurized fluids through the secondary opening 214, and a step 250 of determining a pressure differential between a pressure of the pressurized fluids around the cutting surface 206 relative to a pressure of the pressurized fluids at the inlet 204. Lastly, the method a step 252 of reconfiguring the secondary opening 214 based on the diameter of the drill bit 100, the velocity and the pressure differential.
The step 242 of providing of the secondary opening 214 may be dependent on spatial positions of the plurality of inserts 218 provided on the cutting surface 206 of the drill bit 100. The secondary opening 214 may be positioned such that none of the plurality of the inserts 218 are in direct communication with pressurized fluids exiting from the secondary opening 214. For example, no insert 218 (see
The step 252 of reconfiguring the secondary opening 214 may include determining a diameter of the secondary opening 214. The step 252 may also include determining the total of circumferential areas of the two main openings 208, 208′ and the circumferential areas of the two secondary openings 214, 214′. Further, the step 252 may include reconfiguring the angle 217, 226, 230, 234 (see
The step 238 of providing the inlet 204 in the body 202 of the drill bit 100, the step 240 of providing the main opening 208 and the step 242 of providing the secondary opening 214 may involve one or more machining processes such as, but not limited to, drilling, reaming, boring, tapping, counter-boring, and counter-sinking during fabrication or manufacture of the drill bit 100.
It will be apparent to those skilled in the art that various modifications and variations can be made to the method and/or system of the present disclosure without departing from the scope of the disclosure. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the method and/or system disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope of the disclosure being indicated by the following claims and their equivalent.