FIELD OF THE INVENTION

[0001] The present invention relates to a drill bit sharpener and, in particular, to a sharpener for drill bits of the type having a plurality of drill bit buttons or inserts built into a leading face of the drill bit, and wherein the drill bit sharpener is capable of sharpening all drill bit buttons simultaneously, and may do so without removing the drill bit from a drill rig.

BACKGROUND OF THE INVENTION

[0002] The application of mechanical energy to rock can generally be performed by percussive action (dynamic force in which the drill bit rotates slightly in response to each stroke) or rotary action (static force). Hybrid drilling methods using a combination of percussive and rotary actions are also used. Generally speaking, percussive drilling with top hammers is appropriate for drilling small holes in hard rock, and rotary drilling is appropriate for drilling large holes. Two methods of rotary drilling are pure rotary drilling without hammers, appropriate for large holes in soft to medium rock, and down-the-hole (DTH) drilling with drill bit hammers appropriate for large holes in hard rock. The present invention is concerned mainly with the sharpening of drill bits used in DTH drilling which typically have a concave, convex, flat faced, or drop centre leading face, and a plurality of drill bit buttons built into the leading face which are either domed or ballistic and which extend out from the leading face.

[0003] A drill string is a term commonly used to describe the components connected to the rotary head of a drill rig down to and including the drill bit, the rotary head being responsible for causing rotation of the drill string. In the case of DTH drill strings, these components may include, from bottom up, the drill bit, the drill bit hammer which is typically a piston that is driven by compressed air supplied through the drill string, and a drill rod which houses these components and is typically configured for threaded engagement with the rotary head. The drill bit buttons may extend along or parallel to a central longitudinal axis of the drill rod (referred to herein as straight buttons) or may be angled with respect to this axis (referred to herein as angled buttons). Typically, drill bit buttons located around the centre of the leading face are straight, and those positioned near or around the outer perimeter of the leading face are angled.

[0004] The drill bit buttons are typically constructed of tungsten carbide, and when drilling in hard ground, these buttons start to wear and become flat. For example, a new button which extends out of a drill bit leading face may be eighteen (18) millimetres in diameter and is typically considered worn and should be removed for sharpening when there is an approximately six (6) to eight (8) millimetre wide flat area appearing on top of the button. Sharpening methods that are known to the present Applicant typically require removal of the drill bit from the drill bit ring, and transport of the drill bit away from the drilling location to a sharpening location where drill bit buttons have to be individually sharpened. Sharpening of an individual drill bit button can take up to ten (10) minutes, and drill bits can include from ten (10) up to two hundred (200) buttons.

[0005] Sharpening is typically achieved using a diamond pin indentation configured to be brought into abutment with the tip of a drill bit button and made to rotate, the aim being to shave the tip of the drill bit button to its original domed or ballistic shape. It is estimated that drill bits typically need to be transported away from a drilling site for sharpening up to ten (10) times throughout the life of the drill bit, and backup bits are required on site to replace the bits which have been removed for sharpening so that the sharpening operation may continue. This can lead to inefficiencies and unnecessary cost in view of the number of personnel required to change the drill bit, and that changing a drill bit can take up to twenty (20) minutes. Drill bits are also expensive items and in an average mine site, using current sharpening techniques, up to one hundred (100) drill bits can be required per month.

[0006] It is an object of the present invention to overcome at least some of the aforementioned problems or to provide the public with a useful alternative.

[0007] Any discussion of documents, acts, materials, devices, articles or the like, which has been included in the present specification is solely for the purpose of providing a context for the present invention. It should not be taken as an admission that any or all of the previous discussion forms part of the prior art base or was common general knowledge in the field of the invention as it existed before the priority date of any of the claims herein. SUMMARY OF THE INVENTION

[0008] In one aspect, the present invention provides a sharpener configured to interface with a drill bit and sharpen one or more buttons on the drill bit, the sharpener including a first section including a drill bit engaging means for fixing the drill bit relative to the first section, a second section including at least one pin engaging portion, a first axis of rotation, and one or more sharpening pins which are substantially aligned with each of the one or more drill bit buttons when the drill bit interfaces with the sharpener, and wherein each of the one or more sharpening pins is further configured to be rotatable about a second axis of rotation associated with the sharpening pin, each pin including a first end including a sharpening means configured to interface with a corresponding button with which the pin is aligned, and to sharpen the corresponding button when the pin is caused to rotate about the second axis of rotation associated with the pin, and a second end including an engaging portion for engaging with said at least one pin engaging portion of the second section such that when the first or second section rotates relative to the other about the first axis of rotation, the pin is caused to rotate about the second axis of rotation associated with the pin.

[0009] In an embodiment, the at least one pin engaging portion of the second section is at least one gear and the second end engaging portion of each pin is a splined portion located at or towards a distal end of the pin to engage with said at least one gear.

[0010] In an embodiment, when the second axis of rotation of at least one of the one or more pins is aligned or parallel with the first axis of rotation of the first section, the at least one gear is a ring gear including internally facing teeth configured to engage with the splined portion of the pin.

[0011] In an embodiment, rotation of the first section causes the splined portion of each pin to orbit around inside the ring gear, which causes each pin to rotate about the second axis of rotation associated with each pin.

[0012] In an embodiment, rotation of the second section causes the ring gear to rotate and orbit around the splined portion of each pin, which causes each pin to rotate about the second axis of rotation associated with each pin. [0013] In an embodiment, when the second axis of rotation of at least one of the one or more pins is not aligned or parallel with the first axis of rotation of the first section, the at least one gear is a bevel gear including outwardly facing teeth configured to engage with the splined portion of the pin.

[0014] In an embodiment, rotation of the first section causes the splined portion of each pin to orbit around the bevel gear, which causes each pin to rotate about the second axis of rotation associated with each pin.

[0015] In an embodiment, rotation of the second section causes the bevel gear to rotate and orbit around inside the splined portion of each pin, which causes each pin to rotate about the second axis of rotation associated with each pin.

[0016] In an embodiment, when the sharpener includes one or more first pins that are aligned or parallel with the first axis of rotation of the first section, and one or more second pins that are not aligned or parallel with the first axis of rotation, the at least one gear includes a ring gear including internally facing teeth configured to engage with the splined portion of the one or more first pins and a bevel gear including outwardly facing teeth configured to engage with the splined portion of the one or more second pins.

[0017] In an embodiment, rotation of the first section causes the splined portion of the one or more first pins to orbit around inside the ring gear and the splined portion of the one or more second pins to orbit around the bevel gear, which causes the first and second pins to rotate about each of their second axes of rotation.

[0018] In an embodiment, rotation of the second section causes the ring gear to rotate and orbit around the splined portion of each of the one or more first pins and the bevel gear to rotate and orbit around inside the splined portion of each pin, which causes the first and second pins to rotate about each of their second axes of rotation.

[0019] In an embodiment, the ring gear teeth are arranged to be correspondingly aligned or parallel with the first axis of rotation of the first section.

[0020] In an embodiment, the bevel gear teeth are arranged to be correspondingly not aligned or parallel with the first axis of rotation of the first section, the bevel gear teeth extending along an angle that substantially corresponds with the angle of the pins that are not aligned or parallel with the first axis of rotation of the first section. [0021] In an embodiment, the drill bit engaging means includes at least one protrusion fixed at a distal end to the first section and adapted to engage with at least one corresponding hole in the drill bit.

[0022] In an embodiment, the at least one protrusion is in the form of two protrusions positioned diametrically opposite each other about the first axis of rotation.

[0023] In an embodiment, the sharpening means at the first end of each pin includes a substantially conically shaped indentation adapted to sharpen a respective substantially conically shaped button.

[0024] In an embodiment, the sharpening means at the first end of each pin includes a substantially ballistic shaped indentation adapted to sharpen a respective substantially ballistic shaped button.

[0025] In an embodiment, the sharpening means at the first end of each pin includes diamond surface elements.

[0026] In an embodiment, said first section houses the one or more pins such that each pin is moveable along the second axis of rotation associated with each pin between a retracted and extended position, wherein each pin is in said retracted position during interfacing of the sharpener with the drill bit.

[0027] In an embodiment, when the sharpener has interfaced with the drill bit, each of the one or more pins is caused to move from said retracted position towards the extended position until contact is achieved between each pin and corresponding drill bit button.

[0028] In an embodiment, each pin includes a spring-loaded shaft and ejection of each pin from the retracted to the extended position is achieved by means of compressed air.

[0029] In an embodiment, the second section is fixed relative to ground, and the first section or the drill bit are caused to be rotated relative to ground during a sharpening operation. [0030] In an embodiment, a means of rotating the first section of the sharpener is the drill bit when removed from a drill string and attached to a hydraulic or electric motor, wherein the drill bit is caused to rotate by operating the hydraulic or electric motor.

[0031] In an embodiment, a means of rotating the first section of the sharpener is the drill bit when attached to a drill string on a drill rig, wherein the drill bit is caused to rotate by operating the drill rig to cause rotation of the drill string.

[0032] In an embodiment, the sharpener further includes a moveable support frame which enables the sharpener to be moved between a first position which is not in a path of the drill bit and thereby allows the drill bit to be used in a drilling operation, and a second position in the path of the drill bit to allow the sharpener to interface with the drill bit and be used to sharpen the drill bit.

[0033] In an embodiment, the moveable support frame includes a protective cover for the sharpener which is adapted to substantially cover the sharpener when in said first position to prevent or minimise particles from the drilling operation from entering into a vicinity of the sharpener.

[0034] In a further alternate embodiment, the first section is fixed relative to ground, and the second section is caused to be rotated relative to ground during a sharpening operation.

[0035] In an embodiment, a means of rotating the second section of the sharpener is a hydraulic or electrical motor associated with the sharpener for driving the sharpening operation.

BRIEF DESCRIPTION OF THE FIGURES

[0036] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several implementations of the invention and, together with the description, serve to explain the advantages and principles of the invention. In the drawings:

Figure 1 is a perspective view of a sharpener according to an embodiment of the present invention;

Figure 2 is a top view of the sharpener of Figure 1 ;

Figure 3 is a side cross-sectional view of the sharpener of Figure 1 through line 3-3 of Figure 2;

Figure 4 is an exploded perspective view of the sharpener of Figure 1 ;

Figure 5 is an enlarged view of some of the components shown in Figure 4 in exploded perspective view;

Figure 6 is a perspective view of a drill bit;

Figure 7 is a perspective cross-sectional view of a pin housing of the sharpener of

Figure 1 ;

Figure 8 is a perspective view of the sharpener of Figure 1 having a drill bit interfacing with the sharpener;

Figure 9 is a perspective cross-sectional view of the interfacing sharpener and drill bit of Figure 8; and

Figure 10 is a perspective view of the interfacing sharpener and drill bit of Figure 8 including a slideable support frame and protective cover for the sharpener. DETAILED DESCRIPTION OF EMBODIMENT(S) OF THE INVENTION

[0037] The following detailed description of the invention refers to the accompanying drawings. Although the description includes exemplary embodiments, other embodiments are possible, and changes may be made to the embodiments described without departing from the spirit and scope of the invention. Wherever possible, the same reference numbers will be used throughout the embodiments and the following description to refer to the same and like parts.

[0038] Figures 1 to 5 illustrate a drill bit sharpener 10 according to an embodiment of the present invention, the sharpener 10 configured to sharpen drill bit buttons 12 of a drill bit 14 of the type used in down the hole (DTH) drilling. Such drill bits 14 have a leading face 16 and drill bit buttons 12 are built into the leading face 16 and are typically either domed or ballistic in shape. A drill bit 14 having domed buttons is shown in Figure 6. The leading face 16 of the drill bit shown in Figure 6 is of the drop centre variety, but it is to be understood that other drill bits including alternately configured leading faces can be sharpened using the sharpener 10 of the present invention.

[0039] It is to be further understood that drill bits used in applications other than DTH drilling could potentially be sharpened using sharpener 10. As will be described in more detail further below, the sharpener 10 includes one or more sharpening pins 18 as shown in most detail in Figure 7, which are positioned and configured to interface with the drill bit buttons 12 of a drill bit 14. A sharpener 10 which is interfaced with such a drill bit 14 is shown in Figures 8 and 9.

[0040] The sharpener 10 of Figures 1 to 5 includes what is referred to herein as a "first section" that may include a number of components that are rotatable about the longitudinal axis of rotation 20 (referred to herein at times as a first axis of rotation) shown in Figure 9, and which may include a drill bit engaging means for fixing the drill bit 14 relative to the axis of rotation 20 such that rotation of the first section causes rotation of the drill bit 14 or vice versa. The drill bit engaging means may include at least a top cover 22 from which protrudes two drivers 24 diametrically opposite each other about the axis of rotation 20 and adapted to engage with corresponding holes 26 of the drill bit 14. The top cover 22 may further include two similarly arranged and diametrically opposed bit stops 28 which provide an abutment surface for the drill bit leading face 16 when the drill bit is interfaced with the top cover 22. The skilled addressee would appreciate that the bit stops are necessary to maintain a minimum distance between the leading face 16 of the drill bit 14 and the top cover 22.

[0041] The sharpener 10 may further include what is referred to herein as a "second section" with respect to which the first section may be rotatable, or vice versa, wherein the second section may include at least one pin engaging portion. In the example shown, the at least one pin engaging portion includes two pin engaging portions in the form of a ring gear 30 and a bevel gear 32. The reason for there being two pin engaging portions in this embodiment will become apparent from a further reading of this specification. In an alternate embodiment, the second section components may be caused to rotate with respect to the first section components which would remain stationary together with the drill bit 14 relative to ground. This alternative is described in more detail further below. The description below also clarifies the nature of the engagement between each pin and each of gears 30 and 32.

[0042] It is to be understood that the sharpener 10 may be manufactured and configured according to specific drill bit types. For example, the sharpening pins 18 need to be aligned with drill bit buttons 12 prior to any sharpening operation, and accordingly since there are a variety of drill bits available with different arrangements and configurations of drill bit buttons 12, the sharpener 10 can be manufactured accordingly. In this regard, the sharpener 10 may be manufactured to ensure that the sharpening pins 18 appropriately align with the drill bit buttons 12 upon interfacing of the drill bit 14 with the sharpener 10. The sharpening pins 18 may be associated with the first section such that rotation of the first section causes rotation of the sharpening pins 18 about the axis of rotation 20. Each of the one or more sharpening pins 18 may be further configured to be rotatable about its own axis of rotation (referred to herein at times as a second axis of rotation), shown in the drawings as axis 34.

[0043] In Figure 7, it can be appreciated that each pin includes a first end having a sharpening means configured to interface with a corresponding button 12 with which that particular pin is aligned, and to sharpen that button when the pin is caused to rotate about its own axis 34. The sharpening means may be in the form of a substantially conically shaped indentation 35 (for a conical drill bit button) which sharpens the drill bit button 12 upon rotation, and the indentation 35 my include diamond surface elements to assist in the sharpening operation. It is to be understood that other sharpening indentations and variations may be equally viable. For example, if the drill bit buttons are ballistic then the sharpening indentation may be correspondingly ballistic in shape.

[0044] At an opposite end of each pin 18, there is an engaging portion for engaging with either one of the ring gear 30 or bevel gear 32 depending on the angle of the sharpening pin 18. The engagement between the pin and the gears 30 and 32 may be such that when the first section of the sharpener 10 rotates relative to the second section, or when the second section rotates relative to the first section, each pin 18 is caused to rotate about its own axis of rotation 34 and thereby sharpen the corresponding dill bit buttons 12.

[0045] The engaging portion of each sharpening pin 18 may be in the form of a splined surface 36 configured to engage with either internally facing teeth 38 of the ring gear or outwardly facing teeth 40 of the bevel gear 32, and wherein rotation of the first section of the sharpener 10 causes the splined surface 36 of each pin 18 to orbit around inside the ring gear 30 or around outside of the bevel gear 32. Each of the ring gear 30 and bevel gear 32 may be positioned such that when the axis of rotation of a pin 18 is not aligned or parallel with the axis of rotation 20 it engages with the bevel gear 32, but when the axis of rotation of a pin 18 is aligned or parallel with the axis 20 it engages with the ring gear 30. In other words, the "straight" pins of the sharpener, which align with "straight buttons" of the drill bit, which are shown positioned in a circular arrangement and extending from a substantially central location of the drill bit leading face, extend straight down into the sharpener to engage the internally facing teeth 38 of ring gear 30. The "angled" pins of the sharpener 10, which align with "angled buttons" of the drill bit, which are positioned around a peripheral edge of the drill bit leading face, extend down into the sharpener at an angle to engage the outwardly facing teeth 40 of bevel gear 32 which extend at a substantially corresponding angle.

[0046] The skilled addressee would appreciate that when the drill bit 14 is moved to a position in which it abuts with the bit stops 28 of the drill bit sharpener 10, the sharpening pins 18 and in particular the conically shaped indentation of each sharpening pin will not appropriately interface with each dill bit button 12 to enable sharpening of the buttons. For example, there may be a gap between each drill bit button and pin indentation. The pins may accordingly be moveable in order to meet with each of the drill bit buttons 12 prior to a sharpening operation. In particular, each pin may be ejectable along its axis of rotation 34 from a retracted to an extended position. Each pin may be configured to remain in the retracted position during interfacing of the sharpener 10 with the drill bit 14, and then made to eject so that each pin indentation interfaces with each drill bit button. Different drill bit buttons may be worn to different levels, and ejecting individual pins in this manner ensures that individual drill bit buttons will be appropriately engaged by a sharpening pin regardless of whether one button is a greater distance away from its corresponding pin than another.

[0047] Ejection and retraction of the sharpening pins may be achieved in a number of ways, including for example by each pin including a spring loaded shaft (not shown) at or adjacent the base of each pin wherein the spring loaded action is effected by means of compressed air acting against the shaft. The splined configuration at the base of each pin facilitates its movement between extended and retracted positions whilst also ensuring that engagement with the bevel and ring gears is maintained.

[0048] This first section components described earlier may include housing for the sharpening pins including a main housing 42 and a top housing 44, which may be connected such that rotation of one causes rotation of the other. The main housing 42 may include appropriately positioned and appropriately angled apertures 46 to accept and support the sharpening pins 18 and may be shaped such that the housing extends from adjacent the top housing 44 towards the base of the sharpener 10 where it extends inside a lower bearing 48, which itself rests upon a portion of the bevel gear 32. In the embodiment shown, the bevel gear 32 is not configured to rotate and hence provides a stationary support for the lower bearing 48, although in some configurations the bevel gear 32 could be made to rotate. The top housing 44 may form part of the top face of the sharpener 10 whilst resting above an upper bearing 50.

[0049] In this regard, the housing which supports the pins may be supported by two spaced apart bearings, an upper bearing 50 longitudinally above which the pin housing 42 sits and a lower bearing 48 radially between which the pin housing 42 extends. In resting upon the upper bearing 50 and extending inside the lower bearing 48, the top housing 44 is free to rotate and in turn provides for rotation of the main housing 42 and sharpening pins 18 about the axis of rotation 20. Also associated with the main housing 42 may be bearing retainers 51 and 52 which will be described in more detail below with reference to Figure 7.

[0050] Further components forming part of the first section of the sharpener 10 may include a chamber shroud 54 which extends around the main housing 42 and which may rotate together with the main housing 42. The layshaft 56 and the drain shaft shroud 58 which shrouds a drain shaft 60 may also rotate together with the first section components. The skilled person would appreciate that the purpose of these components is to facilitate air into the sharpening pins 18 to effect ejection and retraction of same, as described earlier, and to also drain water.

[0051] The second section of the sharpener 10 may be considered to include components such as the outer casing 62, the labyrinth 64 which may also form part of the upper face of the sharpener 10 together with the top housing 44 and top cover 22, the bevel gear 32 which may sit upon a lower internal shoulder 66 of the outer casing 62, the ring gear 30 which may be mounted such that it is disposed lower than the bevel gear 32 towards the base of the sharpener 10, and the various components associated with the base plate 68 of the sharpener 10 including the drain shaft 60, and the lay shaft housing 70, both of which are located centrally at the base plate and extend outwardly from the flat plane of the base plate. The outer casing 62 may include a second upper inner shoulder 72 upon which rests the previously described upper bearing 50, and third lower inner shoulder 73 which faces an opposite direction compared with shoulders 66 and 72 to provide a mounting surface for the ring gear 30. It is to be understood that any components of the first or second sections that are depicted in the drawings but not described in detail are considered to be well known components in the art.

[0052] The skilled addressee should now have an appreciation of the internal componentry and arrangement of components inside the sharpener 10 according to the particular embodiment shown. In particular, the drain shaft 60 which is disposed centrally along the axis of rotation 20 extends from the base plate 68 up through to a top portion of the sharpener 10 up through the top cover 22, and therefore acts as a central shaft about which other rotatable and non-rotatable components may be mounted. The lay shaft housing 70 is bolted down to the base plate 68 and is configured to support the lay shaft 56 which in turn contributes to supporting, in a fixed position inside the casing, the bevel gear 32 and ring gear 30 while the drain shaft shroud 58, which may itself be rotatable, performs a similar function for the components in the casing that are rotatable, including for example the pin housing components.

[0053] The second section components may be fixed relative to the ground, while the first section components and the drill bit are caused to rotate relative to the ground during a sharpening operation. The means of rotating the first section may be the drill bit 14 itself such that the drill bit is removed from a drill string (not shown) and attached to a hydraulic or electric motor (not shown), which causes the drill bit and hence one or more of the first section components to rotate by operating the hydraulic or electric motor. In causing at least the pin housing components to rotate about the axis 20, the pins are also caused to also rotate about the axis 20, and interaction of the pins with each of the bevel 32 and ring 30 gears causes the individual pins to rotate about their own axes of rotation 34. As described earlier, when each pin is enabled to rotate about its own axis 34, then by way of engagement between the drill bit buttons and each of their respective sharpener pin indentations, the drill bit buttons become sharpened during such rotational motion of the drill bit and first section components.

[0054] There may be benefits, time savings and efficiencies in being able to sharpen the drill bit at a drill site without removing the bit from its drill string, and in this regard, the drill bit itself may instead be caused to rotate by a drill rig to which the drill string is attached when performing a drilling operation. In moving the sharpener 10 into the path of the drill bit, and interfacing the drill bit with the sharpener whilst attached to the drill rig allows for the drill rig to effectively provide the driving force to cause rotation of the drill bit and one or more of the first section components. In other words, the drill bit and first section components may be caused to rotate by operating the drill rig which causes rotation of the drill string. In this regard, the person skilled in the art would appreciate that the sharpener 10 is portable and may be transported to a mine or other drill site in order to be used to sharpen a drill bit without removing the drill bit from the drill rig. It has been shown that this can allow for sharpening to occur more often, that is, after the drill bit buttons have worn only slightly rather than after they have become significantly worn. Maintaining drill bit buttons in a sharpened state substantially throughout a drilling operation ensures that drilling penetration is maximised. Such a configuration also does away with the need to sharpen individual buttons and the need for backup drill bits to be on hand. Sharpening of an entire drill bit including multiple drill bit buttons can occur using sharpener 10 in as little as two minutes compared with twenty (20) to thirty (30) minutes using existing single button sharpeners which also requires complete removal of the drill bit.

[0055] Figure 10 shows a sharpener 10 according to an embodiment in which the sharpener base plate 68 is mounted above a sliding frame 74. The frame 74 may be movable between a first position in which the sharpener 10 is positioned in the path of the drill bit 14 that is attached to a drill rig (not shown) such that lowering of the drill bit 14 will cause the drill bit to interface with the sharpener 10 in preparation for a sharpening operation, and a second position in which the frame 74 and sharpener 10 are positioned such that they are not in the path of the drill bit 14 and therefore allow the drill bit 14 to be used in its normal drilling operation. The sliding frame 74 may also include a protective cover 76 made to lower over the sharpener 10 when in the second position away from the drill bit to ensure that dust and other particles do not enter the vicinity of the sharpener 10 during the drilling operation. Movement of the sliding frame may be achieved using any known means including for example by a hydraulic arm 78 as shown in Figure 10.

[0056] In an alternate embodiment, one or more of the second section components could be caused to rotate relative to the first section components which could be caused to be fixed relative to ground, that is, in an opposite configuration to that which has been predominantly described above. In this configuration, at least the bevel and ring gears would need to be caused to rotate. The skilled person would understand that causing one or more of the second components to rotate relative to the first will equally result in rotation of each pin about its own axis 34 with respect to corresponding drill bit buttons 12, thereby causing each button 12 to be sharpened by the indentations associated with the end of each of the sharpening pins 18. A means of rotating one or more of the second section components of the sharpener 10 could be in the form of a hydraulic or electric motor (not shown) associated with the sharpener 10.

[0057] The manner in which individual sharpening pins 18 are held within sharpening pin apertures 46 in the main housing 42 and top housing 44 is shown most clearly in Figure 7. Each individual sharpening pin 18 may include two bearings (not shown) to facilitate their rotation and which may be held in place using an internal circlip (not shown) and one or more bearing retainers 51 and 52 (discussed above). In the embodiment shown, upper bearing retainers 51 may be associated with each of the straight sharpening pins and are configured to be secured to an upper surface of the main housing 42 to retain each upper bearing on each straight pin. Similar bearing retainers may be used to retain one or more bearings on each of the angled pins. In the embodiment shown, a single lower bearing retainer 52 is secured to a lower surface of the housing 42 to retain each lower bearing (not shown) on each straight pin. However, it is to be understood that other means of holding each of the straight and angled pins in place inside housing 42 and facilitating rotation thereof could equally well be implemented.

[0058] Not all components of the drill bit sharpener 10 are shown and described. For example, the rotating components may well include additional bearings to facilitate rotation. The fixing means for connecting adjacent components or for fixing stationary components within the outer casing are also not all shown or not described as these are considered to be items that any person skilled in the art could select and utilise during the manufacture of the sharpener 10 without the need to exercise inventive skill or ingenuity.

[0059] The present invention therefore provides a mechanical drill bit sharpener which may use the power of mechanical rotation to turn individual sharpening pins 18 about their respective axes of rotation 34 to sharpen correspondingly aligned drill bit buttons 12 associated with the drill bit 14. The sharpener 10 could be placed in a workshop environment in which drill bits 14 are transported to the workshop and placed in the sharpener whereby a hydraulic or electric motor (not shown) may be operated to cause rotation of the drill bit and thereby rotation of the first section components of the sharpener 10 until the drill bit is refurbished. For example, this application may be suitable for small drill rigs with portable drill arms that may not necessarily have a deck or area to support a sharpener.

[0060] Larger drill rigs do tend to have the available space (usually a deck) to place a sliding frame 74 which supports the mechanical sharpener 10, which enables the sharpener to be placed on the sliding frame 74 so that when the drill bit becomes, for example, two (2) to three (3) millimetres flat the sharpener can easily slide into a position under the drill string to carry out a sharpening operation. The drill bit 14 may then be lowered to interface with the drill bit sharpener, and all buttons 12 on the drill bit engaged by pins 18 which may have a diamond tip or indentation configured to sharpen the buttons and which may be configured to eject out to interface with each button. The drill string may then be rotated through normal operation of the drill rig, which causes all the diamond pins to rotate on the ring gear and/or bevel gear which will again result in re-sharpening the drill bit. The drill string may then be raised and the portable drill bit sharpener can slide out from the path of the drill bit, to allow drilling to commence again with a sharpened drill bit. Depending on ground conditions, testing has shown that the drill bit can sharpened every hole or when two (2) to three (3) millimetres flat. There may be no need to take the drill bit off the drill rig until the life of the drill bit is expired.

[0061] Further advantages and improvements may very well be made to the present invention without deviating from its scope. Although the invention has been shown and described in what is conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope and spirit of the invention, which is not to be limited to the details disclosed herein but is to be accorded the full scope of the claims so as to embrace any and all equivalent devices and apparatus.

[0062] In any claims that follow and in the summary of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprising" is used in the sense of "including", i.e. the features specified may be associated with further features in various embodiments of the invention.

[0063] The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement or any suggestions that the prior art forms part of the common general knowledge.