Shank assembly

Abstract

In one aspect of the invention, a pick comprises a carbide bolster disposed intermediate an impact tip and a shank assembly. The impact tip comprises a superhard material bonded to a carbide substrate, and the tip is bonded to the bolster opposing a base of the bolster. The shank assembly comprises a central axis, a first end that protrudes into a cavity formed in the base of the bolster, and also an inducible attachment mechanism disposed proximate the first end. The inducible attachment mechanism is adapted to attach the shank assembly to the carbide bolster and restrict movement of the shank assembly with respect to the carbide bolster. The attachment mechanism may restrict movement of the shank assembly in a direction parallel to the central axis.

Description

BACKGROUND OF THE INVENTION

Formation degradation, such as pavement milling, mining, or excavating, may result in wear on impact resistant picks. Consequently, many efforts have been made to extend the working life of these picks by optimizing the shape of the picks or the materials with which they are made. Examples of such efforts are disclosed in U.S. Pat. No. 4,944,559 to Sionnet et al., U.S. Pat. No. 5,837,071 to Andersson et al., U.S. Pat. No. 5,417,475 to Graham et al., U.S. Pat. No. 6,051,079 to Andersson et al., and U.S. Pat. No. 4,725,098 to Beach, all of which are herein incorporated by reference for all that they contain.

BRIEF SUMMARY OF THE INVENTION

In one aspect of the invention, a pick comprises a carbide bolster disposed intermediate an impact tip and a shank assembly. The impact tip comprises a superhard material bonded to a carbide substrate, and the tip is bonded to the bolster opposing a base of the bolster. The shank assembly comprises a central axis, a first end that protrudes into a cavity formed in the base of the bolster, and also an inducible attachment mechanism disposed proximate the first end. The inducible attachment mechanism is adapted to attach the shank assembly to the carbide bolster and restrict movement of the shank assembly with respect to the carbide bolster. The attachment mechanism may restrict movement of the shank assembly in a direction parallel to the central axis.

The attachment mechanism may be adapted to restrict rotation of the shank assembly about the central axis when the shank assembly is attached to the carbide bolster. In some embodiments the inducible attachment mechanism may also be adapted to inducibly release the shank assembly from attachment with the carbide bolster.

The inducible attachment mechanism may comprise an insertable locking mechanism and also a locking shaft connected to an expanded locking head. The insertable locking mechanism and locking head may be disposed within the cavity of the carbide bolster and the locking shaft may protrude from the cavity into an inner diameter of the shank assembly. The locking shaft may be adapted for translation in a direction parallel to the central axis of the shank assembly.

The attachment mechanism may comprise a wedge disposed within the cavity of the carbide bolster. In some embodiments the wedge may be fixed to the carbide bolster. The first end of the shank assembly may be adapted to expand when the wedge is inserted into the first end.

The first end of the shank assembly may comprise a plurality of prongs. The plurality of prongs may be adapted to interlock with the cavity of the carbide bolster. An internal surface of the cavity of the bolster may comprise outwardly tapered surfaces. A split ring may be disposed in the cavity of the bolster intermediate the first end of the shank assembly and an inner surface of the bolster.

The shank assembly may comprise inner and outer diameters. The shank assembly may comprise a hollow portion within the inner diameter and may also comprise an opening to the hollow portion in a second end of the shank assembly. The shank assembly may comprise a constricted inner diameter proximate the first end. A wedge may be disposed within the inner diameter of the shank assembly. In some embodiments the wedge may comprise a first set of threads that corresponds to a second set of threads disposed on an inner surface of the shank assembly.

In some embodiments the attachment mechanism may comprise a plurality of extendable arms that are each perpendicular to a central axis of the shank assembly. Each of the plurality of extendable arms may be adapted to interlock with the carbide bolster by extending into a recess disposed in the cavity of the carbide bolster. In some embodiments fluid pressure on an expandable bladder disposed within the shank assembly may cause the bladder to expand and thereby extend the plurality of extendable arms away from the central axis. Translation of an activating mechanism in a direction parallel to the central axis may extend the plurality of extendable arms away from the central axis. The activating mechanism may interlock with at least a portion of at least one of the plurality of extendable arms and thereby maintains the extension of the arm away from the central axis.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional diagram of an embodiment of a milling machine.

FIG. 2 is a cross-sectional diagram of an embodiment of a high-impact resistant pick disposed on a milling drum.

FIG. 3 is a perspective diagram of an embodiment of a wedge.

FIG. 4 is a perspective diagram of an embodiment of a portion of a shank assembly.

FIG. 5 is a cross-sectional diagram of an embodiment of a high-impact resistant pick.

FIG. 6 is a cross-sectional diagram of another embodiment of a pick.

FIG. 7 is a cross-sectional diagram of another embodiment of a pick.

FIG. 8 is a cross-sectional diagram of another embodiment of a pick.

FIG. 9 is an exploded cross-sectional diagram of another embodiment of a pick.

FIG. 10 is an exploded cross-sectional diagram of another embodiment of a pick.

FIG. 11 is a cross-sectional diagram of another embodiment of a pick.

FIG. 12 is a cross-sectional diagram of another embodiment of a pick.

FIG. 13 is a perspective diagram of an embodiment of a split ring.

FIG. 14 is a cross-sectional diagram of another embodiment of a pick.

FIG. 15 is a cross-sectional diagram of another embodiment of a pick.

FIG. 16 is a cross-sectional diagram of another embodiment of a pick.

FIG. 17 is a cross-sectional diagram of another embodiment of a pick.

DETAILED DESCRIPTION OF THE INVENTION AND THE PREFERRED EMBODIMENT

FIG. 1 is a cross-sectional diagram of an embodiment of a plurality of picks 101 attached to a driving mechanism 103, such as a rotating drum connected to the underside of a pavement milling machine 100. The milling machine 100 may be a cold planer used to degrade manmade formations such as a paved surface 104 prior to the placement of a new layer of pavement. Picks 101 may be attached to the driving mechanism 103 bringing the picks 101 into engagement with the formation. A holder 102, which may be a block, an extension in the block or a combination thereof, is attached to the driving mechanism 103, and the pick 101 is inserted into the holder 102. The holder 102 may hold the pick 101 at an angle offset from the direction of rotation, such that the pick 101 engages the pavement at a preferential angle. In addition to milling machines, the pick 101 may be adapted for use in a downhole rotary drill bit, in a horizontal directional drill bit, in trenching machines, in mining machines, and in coal mining machines.

Referring now to FIGS. 2-4, a pick 101a may be designed for high-impact resistance and long life while milling the paved surface 104 of FIG. 1. Exemplary pick 101a comprises a shank assembly 200a comprising a shank 250a having a first end 201a and a second end 202a. The first end 201a may be press fit into a cavity 203a in a base 204a of a bolster 205a. A super hard material 206 is bonded to a cemented metal carbide substrate 207 to form a wear-resistant tip 208, which is then bonded to the bolster 205a opposite the base 204a of the bolster 205a and the first end 201a of the shank 250. The shank 250 may comprise a hard material such as steel, hardened steel, or other materials of similar hardness. The bolster 205a may comprise tungsten, titanium, tantalum, molybdenum, niobium, cobalt and/or combinations thereof. The super hard material 206 may be a material selected from the group consisting of diamond, monocrystalline diamond, polycrystalline diamond, sintered diamond, chemical deposited diamond, physically deposited diamond, natural diamond, infiltrated diamond, layered diamond, thermally stable diamond, silicon-bonded diamond, metal-bonded diamond, silicon carbide, cubic boron nitride, and combinations thereof.

The second end 202a of the shank 250a is disposed within a bore 209a of a holder 102a, which may comprise an extension 210 or a block 211 attached to a driving mechanism 103a, or both the extension 210 and the block 211. The shank 250a may be held into the holder 102a by a retaining clip 212 adapted to fit in an inset portion of the shank 250. An outer surface of the holder 102a may comprise hard-facing in order to provide better wear protection for the holder 102a. The hard-facing may comprise ridges after it is applied, though the ridges may be machined down afterward. The base 204a of the bolster 205a may be in direct contact with an upper face 213 of the holder 102a, and may overhang the holder 102a and hard-facing, which may prevent debris from collecting on the upper face 213. The bore 209a of the holder 102a may comprise hard-facing. One method of hard-facing the bore 209a is case-hardening, during which process the bore 209a is enriched with carbon and/or nitrogen and then heat treated, which hardens the bore 209a and provides wear protection. Other methods of hard-facing the bore may also be used.

The shank 250a may be work-hardened in order to provide resistance to cracking or stress fractures due to forces exerted on the pick by the paved surface 104 of FIG. 1 or the holder 102a. The shank 250a may be work-hardened by shot-peening the shank 250a, chrome plating the shank 250a, enriching the shank 250a with nitrogen, or other methods of work-hardening. The shank 250a may also be rotatably held into the holder 102a, such that the pick 101a is allowed to rotate within the holder 102a. The first end 201a of the shank 250a protrudes into the cavity 203a in the base 204a of the bolster 205a. The shank assembly 200a further comprises an inducible attachment mechanism 214a disposed at the first end 201a of the shank 250a. The inducible attachment mechanism 214a is adapted to attach the shank 250a to the bolster 205a and restrict movement of the shank 250a with respect to the bolster 205a.

In FIG. 2 the inducible attachment mechanism 214a radially expands at least a portion of the shank 250a outward to engage the cavity 203a of the bolster 205a. This engagement may attach the shank 250a to the bolster 205a, thereby preventing movement of the shank 250a with respect to the bolster 205a. The shank 250a may be prevented by the attachment mechanism 214a from moving in a direction parallel to a central axis 403a of the shank 250a. In some embodiments the shank 250a may be preventing by the attachment mechanism 214a from rotating about the central axis 403a of the shank 250a.

In the embodiment of FIG. 2 through FIG. 4, the attachment mechanism 214a comprises a wedge 300a that is disposed within the cavity 203a. FIG. 3 is a perspective diagram of an embodiment of a wedge 300a comprising ridges 301 along a portion of an outside surface 302 of the wedge 300a. FIG. 4 is a perspective diagram of an embodiment of the first end 201a of a shank 250a. The first end 201a comprises a seat 401 into which the wedge 300a may be inserted. As the shank assembly 200a is inserted into the cavity 203a the wedge 300a is forced into the seat 401 of the first end 201a, and thereby an expandable portion 402 of the first end 201a is forced outward, away from the central axis 403a of the shank 250a, and into engagement with an internal surface 405a of the bolster 205a in the cavity 203a. Although in the present embodiment the expandable portion 402 of the first end 201a comprises a plurality of prongs 404a, in some embodiments the expandable portion 402 may extend continuously along a diameter of the shank 250.

In FIG. 2 the internal surface 405a of the cavity 203a comprises an apex 230 formed by an intersection of two outwardly tapered surfaces 215 and the cavity 203a comprises a generally hour-glass shaped geometry. The shank 250a comprises an inner diameter 217a and an outer diameter 216a. A hollow portion 218a of the shank 250a is disposed within the inner diameter 217a along at least a part of a length 219a of the shank 250a. The shank 250a also comprises an opening 220 to the hollow portion 218a. The opening 220 is disposed in the second end 202a of the shank 250a. In FIG. 2 the opening is controlled by a one-way check valve 221. A lubricant reservoir 223 is disposed in the hollow portion 218a intermediate the check valve 221 and a piston assembly 222.

The pick 101a may be lubricated by inserting a lubricant into the reservoir 223 through the bore 209a of the holder 102a and through the one-way valve 221. The piston assembly 222 may be disposed within the bore 209a such that as more lubricant is inserted into the bore 209a, the piston assembly 222 may compress to allow the lubricant to be inserted. After the lubricant is inserted into the bore 209a, the piston assembly 222 may apply pressure on the lubricant, which may force it up around the shank assembly 200a and out of the holder 102a. This may allow the pick 101a to rotate more easily and may decrease friction while the pick 101a rotates for better wear protection of areas in contact with the holder 102a, such as the base 204a of the bolster 205a and the shank 250a.

A weeping seal may be disposed around the shank assembly 200a such that it is in contact with the shank 250a, the bolster 205a, and the holder 102a, which may limit the rate at which the lubricant is expelled from the bore 209a of the holder 102a. The lubricant may also be provided from the driving mechanism 103a. In embodiments, where the driving mechanism 103a is a drum, the drum may comprise a lubrication reservoir and a port may be formed in the drum which leads to the lubrication reservoir. In some embodiments a spiral groove may be formed in the shank 250a or the bore 209a of the holder 102a to aid in exposing the surfaces of the shank 250a and the bore 209a of the holder 102a to the lubricant. In some embodiments, the lubricant is added to the bore 209a of the holder 102a prior to securing the shank 250a within the holder 102a. In such an embodiment, the insertion of the shank 250a may penetrate the volume of the lubricant forcing a portion of the volume to flow around the shank 250a and also compressing the lubricant within the bore 209a of the holder 102a.

Dimensions of the shank assembly 200a and bolster 205a may be important to the function and efficiency of the pick 101a. A ratio of a length 219a of the shank assembly 200a to a length 225 of the bolster 205a may be from 1.75:1 to 2.5:1. A ratio of a maximum width of the bolster 205a to the outer diameter 216 of the shank 250a may be from 1.5:1 to 2.5:1. The first end 201a of the shank 250a may be fitted into the cavity 203a of the bolster 205a to a depth of 0.300 to 0.700 inches. The cavity 203a of the bolster 205a may comprise a depth from 0.600 to 1 inch. The shank 250a may or may not extend into the full depth 305 of the bore 209 of the holder 102a. The shank assembly 200a and bolster 205a may also comprise an interference fit from 0.0005 to 0.005 inches. The bolster may comprise a minimum cross-sectional thickness between the internal surface 405a of the cavity 203 and an outside surface of the bolster 205a of 0.200 inches, preferable at least 0.210 inches. Reducing the volume of the bolster 205a may advantageously reduce the cost of the pick 101a.

The cemented metal carbide substrate 207 may comprise a height of 0.090 to 0.250 inches. The super hard material 206 bonded to the substrate 207 may comprise a substantially pointed geometry with an apex comprising a 0.050 to 0.160 inch radius, and a 0.100 to 0.500 inch thickness from the apex to an interface where the super hard material 206 is bonded to the substrate 207. Preferably, the interface is non-planar, which may help distribute loads on the tip 208 across a larger area of the interface.

The side wall 260 of the superhard material may form an included angle 280 with a central axis 270 of the tip 208 between 30 to 60 degrees. In asphalt milling applications, the inventors have discovered that an optimal included angle 280 is 45 degrees, whereas in mining applications the inventors have discovered that an optimal included angle 280 is between 35 and 40 degrees.

A tip 208 that may be compatible with the present invention is disclosed in U.S. patent application Ser. No. 11/673,634 to Hall and is currently pending.

The wear-resistant tip 208 may be brazed onto the carbide bolster 205 at a braze interface. Braze material used to braze the tip 208 to the bolster 205 may comprise a melting temperature from 700 to 1200 degrees Celsius; preferably the melting temperature is from 800 to 970 degrees Celsius. The braze material may comprise silver, gold, copper nickel, palladium, boron, chromium, silicon, germanium, aluminum, iron, cobalt, manganese, titanium, tin, gallium, vanadium, phosphorus, molybdenum, platinum, or combinations thereof. The braze material may comprise 30 to 62 weight percent palladium, preferable 40 to 50 weight percent palladium. Additionally, the braze material may comprise 30 to 60 weight percent nickel, and 3 to 15 weight percent silicon; preferably the braze material nay comprise 47.2 weight percent nickel, 46.7 weight percent palladium, and 6.1 weight percent silicon. Active cooling during brazing may be critical in some embodiments, since the heat from brazing may leave some residual stress in the bond between the carbide substrate 207 and the super hard material 206. The farther away the super hard material is from the braze interface, the less thermal damage is likely to occur during brazing. Increasing the distance between the brazing interface and the super hard material 206, however, may increase the moment on the carbide substrate 207 and increase stresses at the brazing interface upon impact. The shank assembly 200 may be press fitted into the bolster 205 before or after the tip 208 is brazed onto the bolster 205.

Referring now to the embodiment of FIG. 5, an attachment mechanism 214b is shown wherein a first end 201b of a shank 250b is adapted to expand when a wedge 300b is inserted into the first end 201b. The insertion of the wedge 300b into the first end 201b may coincide with insertion of the shank 250b into a cavity 203b. The expansion of the first end 201b away from a central axis 403b of the shank 250b may strengthen the attachment between the bolster 205b and the shank 250b.

The embodiment of FIG. 6 discloses an attachment mechanism 214c that includes a wedge 300c fixed to a bolster 205c. A shank 250c is adapted to expand when the wedge 300c is inserted into a first end 201c of the shank 250c cemented metal carbide.

FIG. 7 discloses an embodiment of the invention in which an attachment mechanism 214d is an outwardly tapered surface 701 disposed on a first end 201d of a shank 250d. As the shank 250d is inserted into a cavity 203d, the tapered surface 701 may attach a bolster 205d and the shank 250d by expanding the first end 201d of the shank 250d into contact with an internal surface 405d of the cavity 203d.

Referring now to FIG. 8, an embodiment is disclosed in which a plurality of prongs 404e are adapted to interlock with a cavity 203e of a bolster 205e. The prongs 404e may have a characteristic of a flexible resistance against moving toward the central axis 403e defined by its spring constant K. This flexible resistance may generate a force directed away from the central axis 403e and toward an internal surface 405e of the cavity 203e. This force may strengthen the connection between the shank 250e and the bolster 205e.

In the present embodiment a first end 201e comprises a ledge 801 and the prongs 404e are tapered inward from the ledge 801 toward a central axis 403e of a shank 250e. The cavity 203e is shaped to receive the plurality of prongs 404e and to interlock with the prongs 404e. As the first end 201e of the shank 250e enters the cavity 203e the prongs 404e may flex toward the central axis 403e.

The shank 250e may be adapted to snap into place as the ledge 801 enters the cavity 203e so that the ledge 801 rests inside the cavity 203e.

Although the present embodiment discloses an entirely hollow shank 250e, in some embodiments a hollow portion 218e of the shank 250e may extend along only a portion of the length 419e of the shank 250e.

Referring now to FIG. 9, an embodiment is disclosed in which a shank assembly 200f comprises a wedge 300f and a shank 250f having a constricted inner diameter 901f proximate a first end 201f. The constricted inner diameter 901f is smaller than an inner diameter 216f. The wedge 300f may be inserted into the shank 250f by passing the wedge 300f from a second end 202f towards the first end 201f. As the wedge 300f approaches the first end 201f, the constricted diameter 901f may cause the wedge 300f to exert a force on the shank 250f that is directed away from a central axis 403f of the shank 250f. This force may attach the shank 250f assembly 200 to a bolster 205f. The wedge 300f may then still be disposed within the inner diameter 216f.

In FIG. 10 an embodiment of a shank assembly 200g is disclosed in which a wedge 300g comprises a first set of threads 1001 that correspond to a second set of threads 1002. The second set of thread 1002 is disposed on an inner surface 1003 of a shank 250g. As the wedge 300g approaches a first end 201g of a shank 250g, the wedge 300g may be rotated about a central axis 403g of the shank 250g and the first set of threads 1001 may interlock with the second set of threads 1002. This may maintain the wedge 300g inside an inner diameter 216g and proximate the first end 201g and a constricted diameter 901g of the shank 250g. This feature may also allow the wedge 300g to be removed by rotating the wedge 300g about the central axis 403g in a direction opposite an original direction used to place the wedge 300g proximate the constricted diameter 901g. In this embodiment the attachment mechanism 214g is adapted to inducibly release the shank 250g from attachment with a bolster 205g.

Referring now to the embodiment of FIG. 11, a split ring 1101 may be disposed in a cavity 203h of a bolster 205h intermediate a first end 201h of a shank 250h and an internal surface 405h of the bolster 205h. Attachment of the shank 250h to the bolster 205h may induce stress on the bolster 205h. The split ring 1101 may mediate the effect of this stress on the bolster 205h.

FIG. 11 discloses an embodiment where a first end 201h of shank 250h comprises ridges 1102 on an outer diameter of the shank 250h. The ridges 1102 may help maintain contact between the shank 250h and the split ring 1101. In some embodiments the split ring 1101 may be press fit into the cavity 203h of the bolster 205h.

The embodiment of FIG. 12 discloses the split ring 1101 may be disposed in a cavity 203i of a bolster 205i intermediate a first end 201i of a shank 250i and an internal surface 405i of the bolster 205i. Attachment of the shank 250i to the bolster 205i may induce stress on the bolster 205i. The split ring 1101 may mediate the effect of this stress on the bolster 205i when the first end 201i of the shank 250i is press fit into the cavity 203i.

FIG. 13 discloses a split ring 1101 for use in the embodiments of FIG. 11 and FIG. 12.

Referring now to FIG. 14, an attachment mechanism 214j comprises a plurality of extendable arms 1401j that are each perpendicular to a central axis 403j of the shank assembly 200j. Each of the extendable arms 1401j is adapted to interlock with the bolster 205j by extending into a recess 1402j in an internal surface 405j of a cavity 203j of a bolster 205j. The extendable arms 1401j may then maintain attachment between the shank assembly 200j and the bolster 205j. FIG. 14 also discloses an embodiment in which translation of an activating mechanism 1403j in a direction 1407j parallel to the central axis 403j of the shank assembly 200j extends the plurality of extendable arms 1401j away from the central axis 404

In FIG. 14 the activating mechanism 1403j is easily removable from the attachment mechanism 214j. The activating mechanism 1403j comprises a plurality of grooves 1404 adapted to interlock with a plurality of protrusions 1405 disposed on an internal end 1406 of the extendable arms 1401j. The activating mechanism 1403j thereby interlocks with at least a portion of at least one of the extendable arms 1401j and thereby maintains the extension of the arm 1401j away from the central axis 403j. The shank assembly 200j may be released from the bolster 205j by pulling the activating mechanism 1403j away from the rest of the attachment mechanism 214j.

Referring now to FIG. 15, an attachment mechanism 214j includes a plurality of extendable arms 1401k that are each perpendicular to a central axis 403k of the shank assembly 200k. Each of the extendable arms 1401k is adapted to interlock with a bolster 205k by extending into a recess 1402k in an internal surface 405k of a cavity 203k of the bolster 205k. The extendable arms 1401k may then maintain attachment between the shank assembly 200k and the bolster 205k. FIG. 15 also discloses an embodiment in which translation of an activating mechanism 1403k in a direction 1407k parallel to the central axis 403k of the shank assembly 200k extends the plurality of extendable arms 1401k away from the central axis 403k. In FIG. 15 the activating mechanism 1403k is fixed to the extendable arms 1401k.

FIG. 16 discloses an embodiment in which fluid pressure on an expandable bladder 1601 disposed within the shank assembly 200L urges the bladder 1601 to expand. As the bladder 1601 expands a plurality of extendable arms 1401L extend away from a central axis 403L of the shank assembly 200L and into a recess 14021 in an internal surface 405L of a cavity 203L of a bolster 205L. A funnel 1602 may be used to direct a fluid into the expandable bladder 1601. An elastomeric seal 1603 may be disposed proximate the expandable bladder 1601 and may allow the bladder 1601 to open while maintaining a seal against the bladder 1601. This may prevent the fluid from leaving the bladder 1601. The bladder 1601 may be adapted to expand to a predetermined distance, after which the bladder 1601 may no longer expand under the fluid pressure. In some embodiments the fluid may be a lubricant. The expandable bladder 1601 may be adapted to return to its original shape once the fluid is removed relieving fluid pressure.

Referring now to the embodiment of a shank assembly 200m of FIG. 17, an inducible attachment mechanism 214m comprises a insertable locking mechanism 1701 and also a locking shaft 1702. The locking shaft 1702 is connected to an expanded locking head 1703. The insertable locking mechanism 1701 and locking head 1703 are disposed within a cavity 203m of a bolster 205m. The locking shaft 1702 protrudes from the cavity 203m and into an inner diameter 216m of a shank 250m. The locking shaft 1702 is disposed proximate a constricted inner diameter 901m proximate a first end 201m of the shank 250m. The locking shaft 1702 is adapted for translation in a direction parallel to a central axis 403m of the shank assembly 200m. The shank 250m may pass through the opening 1710 of the cavity 203m and then the locking mechanism 1701 may be inserted afterwards. The locking mechanism 1701 may be retained within the cavity 203m through a retention shoulder formed in the cavity 203m, while protruding into the cavity 203m and preventing the shank 250m from exiting the opening 1710.

When the first end 201m of the shank 250m is inserted into the cavity 203m, the locking head 1703 may be extended away from the constricted inner diameter 901m of the shank 250m. The insertable locking mechanism 1701 may be disposed around the locking shaft 1702 and be intermediate the locking head 1703 and the constricted inner diameter 901m. The insertable locking mechanism 1701 may comprise an elastomeric material and may be flexible. In some embodiments the insertable locking mechanism 1701 may comprise a metal and/or a flexible metal. The insertable locking mechanism 1701 may be a split ring, a coiled ring, a rigid ring, segments, balls, or combinations thereof.

In embodiments where the insertable locking mechanism 1701 is flexible, the insertable locking mechanism 1701 may comprise a breadth 1704 that is larger than an opening 1710 of the cavity 203m. In such embodiments the insertable locking mechanism 1701 may compress to have a smaller breadth 1704′ than the available distance 1705. Once the insertable locking mechanism 1701 is past the opening 1710, the insertable locking mechanism 1701 may expand to comprise its original or substantially original breadth 1704.

With both the insertable locking mechanism 1701 and the locking head 1703 past the opening 1710, the first end 201m of the shank 250m may be further inserted into the cavity 203m of the bolster 205m. Once the shank 250m is inserted into the cavity 203m to a desired depth, a nut 1706 may be threaded onto an exposed end 1707 of the locking shaft 1702 until the nut 1706 contacts a ledge 1708 proximate the constricted inner diameter 901m. This contact and further threading of the nut 1706 on the locking shaft 1702 may cause the locking shaft 1702 to move toward a second end 202m of the shank 250m in a direction parallel to the central axis 403m of the shank assembly 200m. This may also result in moving the locking head 1702 into contact with the insertable locking mechanism 1701, and bringing the insertable locking mechanism 1701 into contact with the internal surface 405m of the bolster 205m.

Once the nut 1706 is threaded tightly onto the locking shaft 1702, the locking head 1703 and insertable locking mechanism 1701 of the attachment mechanism 214 together are too wide to be removed from the opening 1710.

The contact between the locking head 1703 and the bolster 205m via the insertable locking mechanism 1701 may be sufficient to prevent both rotation of the shank assembly 200m about its central axis 403m and movement of the shank assembly 200m in a direction parallel to its central axis 403m.

In the present embodiment the attachment mechanism 214m is also adapted to inducibly release the shank assembly 200m from attachment with the bolster 205m by removing the nut 1706 from the locking shaft 1702.

Whereas the present invention has been described in particular relation to the drawings attached hereto, it should be understood that other and further modifications apart from those shown or suggested herein, may be made within the scope and spirit of the present invention.

Claims

1. A pick, comprising: a bolster including a base, a cavity disposed within said base, and a surface opposite said base;a tip disposed adjacent said surface, the tip including a superhard materialbonded to a carbide substrate, the carbide substrate being bonded to said surface; anda shank assembly including; a shank having a central axis, a first end, and a second end, said first end protruding into said cavity and said first end including a radially expandable portion;an attachment mechanism disposed at said first end, the attachment mechanism configured to expand said radially expandable portion about said axis within said cavity, thereby engaging an internal surface of said cavity.

2. The pick of claim 1, wherein said attachment mechanism is adapted to restrict rotation of the shank about said central axis when said shank is attached to the bolster.

3. The pick of claim 1, wherein said attachment mechanism is further adapted to release said shank assembly from attachment with said bolster.

4. The pick of claim 1, wherein said attachment mechanism comprises a insertable locking mechanism and a locking shaft connected to an expanded locking head, said insertable locking mechanism and said locking head being disposed within said cavity of said carbide bolster, and said locking shaft protruding from said cavity into an inner diameter of the shank assembly and being adapted for translation in a direction parallel to said central axis of the shank assembly.

5. The pick of claim 1, wherein said attachment mechanism comprises a wedge disposed within said cavity of the bolster.

6. The pick of claim 5, wherein said wedge is fixed to said bolster.

7. The pick of claim 1, wherein said first end of the shank assembly is adapted to expand when a wedge is inserted into said first end.

8. The pick of claim 1, wherein said first end of said shank assembly has a plurality of prongs that are adapted to interlock with said cavity of the bolster.

9. The pick of claim 1, wherein said attachment mechanism attaches said shank assembly to said bolster by radially expanding at least a portion of said shank assembly.

10. The pick of claim 1, wherein an internal surface of said cavity comprises outwardly tapered surfaces.

11. The pick of claim 1, wherein said shank assembly comprises a hollow portion disposed within an inner diameter and an opening to the hollow portion in a second end of said shank assembly.

12. The pick of claim 1, wherein said shank assembly includes a wedge disposed within an inner diameter of said shank.

13. The pick of claim 12, wherein said wedge includes a first set of threads that corresponds to a second set of threads disposed on an inner surface of said shank.

14. The pick of claim 1, wherein a split ring is disposed in said cavity of said bolster intermediate said first end of said shank assembly and an inner surface of said bolster.

15. The pick of claim 1, wherein said attachment mechanism has a plurality of extendable arms that are each perpendicular to a central axis of said shank assembly.

16. The pick of claim 15, wherein each of said plurality of extendable arms is adapted to interlock with said bolster by extending into a recess disposed in said cavity of said carbide bolster.

17. The pick of claim 15, wherein fluid pressure on an expandable ring disposed within said shank assembly causes said ring to expand and thereby extend said plurality of extendable arms away from said central axis.

18. The pick of claim 15, wherein translation of an activating mechanism in a direction parallel to said central axis extends the plurality of extendable arms away from said central axis.

19. The pick of claim 18, wherein said activating mechanism interlocks with at least a portion of at least one of said plurality of extendable arms and thereby maintains the extension of the arm away from said central axis.

20. The pick of claim 12, wherein said wedge is disposed at said first end of said shank.

21. The pick of claim 12, wherein said shank further includes a seat disposed at said radially expanding portion, said seat being configured to receive said wedge.

22. The pick of claim 1, wherein said radially expanding portion is deformable.

23. The pick of claim 1, wherein said radially expanding portion includes a prong extending axially.