GRINDING TOOL FOR BUTTONS ON A ROCK DRILL BIT

Abstract

A grinding cup for detachable connection to the output drive shaft of a grinding machine for grinding buttons on drill bits or cutters, said grinding cup having top and bottom surfaces and consisting of a lower grinding section and an upper body section with a centrally disposed recess formed in the bottom surface of the grinding section; said body section having a centrally disposed upright drive section formed on the top surface of the grinding cup, said drive section shaped and sized to both driveably engage within a corresponding recess at end of the output drive shaft and provide axial and radial support and retaining means for detachably connecting the grinding cup to the output drive shaft wherein said drive section has a non-circular cross section and is tapered from the top surface of the grinding cup to the free end of the drive section.

Claims

1. A grinding cup for detachable connection to the output drive shaft of a grinding machine for grinding buttons on drill bits or cutters, said grinding cup having top and bottom surfaces and consisting of a lower grinding section and an upper body section co-axial with said grinding section to form said grinding cup with a centrally disposed recess formed in the bottom surface of the grinding section having the desired profile for the button to be ground; the improvement characterized by said body section having a centrally disposed upright drive section, said drive section shaped and sized to driveably engage within a corresponding recess at end of the output drive shaft of said grinding machine and retaining means for detachably connecting the grinding cup to the output drive shaft of the grinding machine wherein said drive section has a non-circular cross section and is tapered from the top surface of the grinding section to the free end of the drive section.

2. A grinding cup according to claim 1 wherein the drive section has an elliptical cross section.

3. A grinding cup according to claim 1 or 2 wherein the upper body section has a base with the centrally disposed upright drive section formed on a top surface of the base.

4. A grinding cup according to claim 1, 2 or 3 wherein means to connect the grinding section to the upper body section are provided on the top surface of the grinding section.

5. A grinding cup according to claim 4 wherein the means to connect the grinding section to the upper body section consists of a generally cylindrical stub centrally located on the top surface of the grinding section, the stub being sized and shaped to be inserted into a corresponding cavity on the upper body section in a manner that will prevent the grinding section from rotating or spinning free relative to the upper body section and that will support axial, radial, torsion and feed forces associated with the use of the grinding cup.

6. A grinding cup according to claim 5 wherein the bottom surface of the base on the upper body section has cavity formed therein sized and shaped to accommodate the cylindrical stub centrally located on the top surface of the grinding section.

7. A grinding cup according to any one of claims 1-6 wherein retaining means for detachably connecting the grinding cup to the output drive shaft of the grinding machine are provided on the upright drive section.

8. A grinding cup according to claim 7 wherein the retaining means 38 comprises an annular groove in the outer surface of the upright drive section sized and shaped to retain an O-ring.

9. A grinding cup according to claim 3 wherein the grinding cup is one in a series of grinding cups for grinding the working tips or buttons of rock drill bits wherein the working tips or buttons have a diameter of about 6 mm to 26 mm and a desired profile, and wherein the base of the upper body section of each grinding cup in the series is sized so the distance from the top surface of the base to the center point of the radius of the convex recess in the grinding section is constant across the series of grinding cups.

10. A holder device for detachable connection of a grinding cup to a grinding machine, said grinding machine having a pneumatically, hydraulically or electrically driven motor which drives an output shaft, the holder device comprising a rotatable drive member having a free end adapted to extend axially away from the the grinding machine, a non-circular recess in the free end of the drive member with a coaxial passageway extending from the recess the length of the drive member or part thereof and through which coolant fluid may be directed to a grinding cup supported thereon, the cross-section of the recess being tapered inwardly from the free end of the drive member.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order that the disclosure may be more clearly understood, embodiments will now be described in detail by way of example, with reference to the accompanying drawings, in which:

[0021] FIG. 1 is perspective view from the right side of one embodiment of a grinding apparatus having a grinding machine carried for vertical and horizontal adjustment by a support system, and means for holding the bit(s) to be ground.

[0022] FIG. 2 is a perspective view from the left side of another embodiment of a grinding apparatus suitable for mobile applications and having a griding machine carried for vertical and horizontal adjustment by a support system and means for holding the bit(s)to be ground.

[0023] FIG. 3 is an enlarged view of a grinding machine of FIG. 1 having a spindle assembly including an ouput drive shaft according to the present disclosure.

[0024] FIG. 4 is an enlarged vertical cross section of the spindle assembly of the grinding machine of FIG. 2.

[0025] FIG. 5 is a front plan view of part of one embodiment of a grinding cup according to the present disclosure.

[0026] FIG. 6 is a partial cross-section of the grinding cup of FIG. 5 along line 5-5.

[0027] FIG. 7 is a top plan view of the grinding cup of FIG. 5.

[0028] FIG. 8 is a front plan view of one embodiment of a lower grinding section of the grinding cup of FIG. 5.

[0029] FIG. 9 is a perspective view of an embodiment of a holder device in the form of a spindle for a grinding machine of FIG. 3 according to the present disclosure with the grinding cup of FIG. 5 attached to the spindle.

[0030] FIG. 10 is a perspective view of the spindle and grinding cup of FIG. 9 with the grinding cup detached from the spindle.

[0031] FIG. 11 is a front plan view of the spindle and grinding cup of FIG. 9.

[0032] FIG. 12 is a cross section of the spindle and grinding cup of FIG. 11 along line A-A.

[0033] FIG. 13 is a side by side view in cross-section of four grinding cups in a series of grinding cups according to the present disclosure, each of said grinding cups sized to grind a different size of button.

DETAILED DESCRIPTION

[0034] With reference to the FIG. 1 one embodiment of a grinding apparatus is generally indicated at 1. The grinding apparatus 1 includes a grinding machine 2, means for holding one or more bits to be ground generally indicated at 3 and a support system generally indicated at 4. The grinding machine 2, means for holding the bits 3 and support system 4 are arranged to permit relative movement between the grinding machine 2 and the bit to be ground to permit alignment of the grinding machine 2 with the longitudinal axis of the buttons on the bit. The grinding apparatus 1 has a control system, part of which is generally indicated at 5, having a programmable operator control panel 6 capable of directly or indirectly monitoring and adjusting one or more operational parameters. The operational parameters may include feed pressure, grinding cup RPM, grinding time and other parameters as noted herein.

[0035] In the grinding apparatus 1 shown in FIG. 1, the grinding machine 2 is carried by support system 4 which includes an arm or lever system 7 journaled on a stand 8 attached to the rear 9 of an open box 10. The bit holder means 3 consists of a table 11 mounted within the box 10.

[0036] FIG. 2 illustrates a more compact grinding apparatus optionally suitable for mobile applications. The grinding apparatus is generally indicated at 20. The grinding apparatus 20 includes a grinding machine 22, means for holding one or more bits to be ground generally indicated at 23 and a support system generally indicated at 24. The grinding machine 22, means for holding the bits 23 and support system 24 are arranged to permit relative movement been the grinding machine 22 and the bit to be ground to permit alignment of the grinding machine 22 with the longitudinal axis of the buttons on the bit. The grinding apparatus 20 has a control system, part of which is generally indicated at 25, having a programmable operator control panel 26 capable of directly or indirectly monitoring and adjusting one or more operational parameters. The operational parameters of most interest are selected from the group consisting of feed pressure, grinding cup RPM and grinding time.

[0037] In the embodiment of the grinding apparatus 20 shown the grinding machine 22 is carried by support system 24 which includes an arm or lever system 27 attached to the frame 28.

[0038] In FIGS. 3 & 4, an embodiment of a grinding machine 2,22 suitable for use with the grinding apparatus 1,20 of either FIG. 1 or 2. FIGS. 3 & 4 show the grinding machine 2,22 attached to plates below a control box 5,24. The grinding machine 2,22 is locked in place by levers 36. A water-cooled electric motor, generally indicated at 35, has an exterior housing defining a chamber in which the rotor and stator are located. Within the wall of the housing are located a series of longitudinal channels for the cooling water. Ports permit water in and water out respectively. A drive coupling at the bottom of housing permits attachment of the spindle assembly 45.

[0039] The drive coupling is inserted into the mating drive coupling 50 on spindle assembly 45. The spindle assembly 45 has an output drive shaft 46 to which a grinding cup can be connected. The spindle assembly 45 is attached to the electric motor housing by bolts 47. Coolant water for delivery to the grinding cup surface is provided though connection 48. The electric motor 35 is preferably a three-phase motor and power is connected through connection 51 to connection box. A flexible splash cup 53 is placed around the output drive shaft 46 of spindle assembly 45. The motor can be hydraulic, electric or the like without departing from the substance of the present invention. The dimensions of the casing are such that the grinding machine may be handled manually if desired. For the latter purpose, the casing is provided with handles projecting diametrically oppositely outwardly from the casing. Suitably connected to the output drive shaft 46 by any conventional means is a holder device 54. In the illustrated embodiment in FIGS. 9-12, the holder device 54 is an integral extension of the shaft 46 which constitutes a rotatable elongate drive member 55. The shaft 46 and drive member 55 are provided with a coaxial passageway 56 extending along the length or part thereof and through which coolant/flushing fluid may be directed to a grinding cup 60 supported thereon. The configuration of the holder device is set out in FIGS. 9-12.

[0040] FIGS. 5-8 illustrate one embodiment of a grinding cup 60 for detachable connection to the output drive shaft of a grinding machine for grinding buttons on drill bits or cutters. The grinding cup 60 consists of a lower grinding section generally indicated at 61 and an upper body section 62 co-axial with said grinding section 61 to form said grinding cup 60. A centrally disposed recess 63 is formed in the bottom surface 64 of the grinding section having the desired profile for the button to be ground.

[0041] The bottom (grinding) surface 64 of the grinding section is formed from a material capable of grinding the tungsten carbide button bits. In the embodiment, the grinding surface is formed from a metal and diamond matrix. The peripheral edge 72 in the bottom surface 64 is beveled to facilitate the removal of steel from the face of the bit around the base of the button during grinding.

[0042] The body section 62 has a base 65 having a centrally disposed upright drive section 66 formed on the top surface 67 of the base 65. The drive section 66 is shaped and sized to driveably engage within a corresponding recess (see FIGS. 9 and 11) at end of the output drive shaft of said grinding machine. Retaining means, generally indicated at 68, for detachably connecting the grinding cup to the output drive shaft of the grinding machine are provided on the upright drive section. In the embodiment illustrated the retaining means 68 comprises an annular groove 69 in the outer surface 70 of the upright drive section 66 sized and shaped to retain an O-ring (not shown).

[0043] The upright drive section 66 has a non-circular cross section and is tapered from the top surface 67 of the base 65 to the free end 71 of the drive section 66. In the embodiment illustrated in FIGS. 5-6, the upright drive section 66 has a truncated elliptical cone shape. The peripheral edge of the bottom 79 of the drive section 36 is the same as or smaller than the diameter of the top surface 67 of base 65.

[0044] A passageway 73 is provided in the drive section 66. The passageway 73 is co-axial with the up-right drive section 66 and communicates with one or more openings (not shown) on the grinding surface 64 through which coolant/flushing fluid may be directed to the surface of the button being ground during grinding.

[0045] As shown in FIG. 8, integral with and adjacent the top surface 74 of the grinding section 61 are means 75 to connect the grinding section 61 to the upper body section 62. The means 75 to connect the grinding section 61 to the upper body section 62 can be formed integrally with the grinding section 61 and machined to the desired configuration or cast separately and attached to the top surface 74 of the grinding section 61. In the embodiment illustrated in FIG. 7, the means 75 to connect the grinding section 61 to the upper body section 62, consists of a generally cylindrical stub 76 centrally located on the top surface 74 of the grinding section 61. The stub 76 is intended to be inserted into a corresponding cavity on the upper body section 62 in a manner (1) that will prevent the grinding section 61 from rotating or spinning free relative to the upper body section 62 and (2) that will support axial, radial, torsion and feed forces associated with the use of the grinding cup. In the preferred embodiment illustrated the stub 76 is press fit into the drive connection member and the grinding section 61 TIG welded to the upper body section 62. Alternatively a stub on the upper body section 62 could fit into a corresponding cavity on the lower grinding section. Some examples of other possible connection methods are taper fits, threaded connections, adhesives, solder, friction welding and pins. The stub 76 could have a non-circular cross-section. It may be desireable to have stub 76 be in the form of an elliptical tapered cone.

[0046] The bottom surface 77 of base 65 on the upper body section 62 has cavity 78 formed therein sized and shaped to accommodate the cylindrical stub 76 centrally located on the top surface 74 of the grinding section 61.

[0047] In the embodiment illustrated grinding cup 60 is one in a series of grinding cups for grinding the working tips or buttons of rock drill bits wherein the working tips or buttons have a diameter of about 6 mm to 26 mm and a desired profile. The base 65 of the upper body section 62 of each grinding cup 60 in the series may be a constant height across the series of grinding cups 60a, 60b, 60c and 60d as shown in FIG. 13. Alternatively the base 65 may be a constant height thru a group in the series of grinding cups and vary in height for the next group.

[0048] Referring to FIGS. 1-4, a grinding machine 2,22 is illustrated which includes a motor housing or casing within which is suitably supported a rotary motor. The motor can be hydraulic, electric or the like without departing from the substance of the present invention. The dimensions of the casing are such that the grinding machine may be handled manually if desired. For the latter purpose, the casing is provided with handles projecting diametrically oppositely outwardly from the casing. The motor drives an output drive shaft. Suitably connected to the output drive shaft by any conventional means is a holder device 54. In the illustrated embodiment in FIGS. 9-12, the holder device is an integral extension of the shaft 46 which constitutes a rotatable elongate drive member 55. The shaft 46 and drive member 55 are provided with a coaxial passageway 56 extending along the length or part thereof and through which coolant/flushing fluid may be directed to a grinding cup 60 supported thereon, the grinding cup being shown in FIGS. 5-8 and described in detail above. An end portion 57 of the elongate drive member 55, extending from its free end 59, is provided with a non-circular recess 106 adapted to accommodate a corresponding sized and shaped upright drive section 66 on grinding cup 60. As shown in FIGS. 9-16, the exterior wall 70 of the upright drive section 66 on grinding cup 60 is adapted to driveably engage within recess 106 centrally disposed in the free end 59 of elongate drive member 55. In the embodiment illustrated the interior wall 107 of the recess 106 in drive member 55 is machined to an elliptical cross section and tapering inwardly from the end 59 of the drive member 55. This design permits the upright drive section 66 of grinding cup 60 to be inserted easily within recess 106 without the necessity of specific alignment of the drive member and grinding cup. The grinding cup can simply be pushed on the drive member 55. When positioned in recess 106, the drive member 55 will rotate the grinding cup without slipping when in use. During grinding, the feed pressure applied to the grinding machine results in the grinding cup 60 being pressed securely within recess 106 providing a rigid connection to reduce wobbling of the grinding cup during grinding. Further the present disclosure maximizes the contact surfaces between the upright drive section 62 on grinding cup 60 and the interior wall 107 of recess 106 on drive member 55. This reduces the wear to all key drive/contact surfaces of the output drive shaft (rotor) and grinding cup which provide consistent, proper alignment between grinding cup and or adapter and the rotor during operation.

[0049] Retaining means may be provided in recess 106 of drive member 55 to detachably retain the grinding cup 60 so that grinding cup 60 will not fly off during use but can still be easily removed or changed after use. The retaining means may include one or more annular grooves in the interior wall of the recess 106 in drive member 55. O-rings or expansion rings may be inserted into the grooves.

[0050] In the embodiment illustrated, both the grinding cup 60 and drive member 55 are fabricated from stainless steel to prevent corrosion and to facilitate clean up after grinding.

[0051] Having illustrated and described a preferred embodiment of the invention and certain possible modifications thereto, it should be apparent to those of ordinary skill in the art that the invention permits of further modification in arrangement and detail and is not restricted to the specific semi-automatic grinding apparatus illustrated. For example the design of the upper body section of the grinding cup and the free end of the output drive shaft can be reversed. In this embodiment the free end of the output drive shaft has a non-circular cross-section and is tapered. The tapered end of the output drive shaft is sized and shaped to fit within a corresponding recess in the top surface of the upper body section of the grinding cup.

[0052] The present disclosure utilizes drive means to provide both axial and radially support and transfer torosional forces. A non-circular tapered connection provides both support and drive. The resistance of the connection to slippage improves as the feed pressure increases, resulting in a relative increase in support and drive capacity as feed increases. However the grinding cup can still be easily removed from the output drive shaft after grinding with no more than a light tap from the side.

[0053] It will be appreciated that the above description related to the preferred embodiment by way of example only. Many variations on the invention will be obvious to those knowledgeable in the field, and such obvious variations are within the scope of the invention as described and claimed, whether or not expressly described.