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.
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.
Referring now to
The second end 202 of the shank assembly 200 is disposed within a bore 209 of a holder 102, which may comprise an extension 210, a block 211 attached to the driving mechanism 103, or both. The shank assembly 200 may be held into the holder 102 by a retaining clip 212 adapted to fit in an inset portion of the shank assembly 200. An outer surface of the holder 102 may comprise hard-facing in order to provide better wear protection for the holder 102. The hard-facing may comprise ridges after it is applied, though the ridges may be machined down afterward. The base 204 of the bolster 205 may be in direct contact with an upper face 213 of the holder 102, and may overhang the holder 102 and hard-facing, which may prevent debris from collecting on the upper face 213. The bore 209 of the holder 102 may comprise hard-facing. One method of hard-facing the bore is case-hardening, during which process the bore is enriched with carbon and/or nitrogen and then heat treated, which hardens the bore and provides wear protection although other methods of hard-facing the bore may also be used.
The shank assembly 200 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 or the holder 102. The shank assembly 200 may be work-hardened by shot-peening the shank, chrome plating the shank, enriching the shank with nitrogen, or other methods of work-hardening. The shank may also be rotatably held into the holder, such that the pick 101 is allowed to rotate within the holder 102. The first end 201 of the shank assembly 200 protrudes into the cavity 203 in the base 204 of the bolster 205 and also comprises an inducible attachment mechanism 214. The inducible attachment mechanism 214 is adapted to attach the shank assembly 200 to the carbide bolster 205 and restrict movement of the shank assembly 200 with respect to the carbide bolster 205. In
In the present embodiment the attachment mechanism 214 comprises a wedge 300 that is disposed within the cavity 203.
In
The pick 101 may be lubricated by inserting a lubricant into the reservoir 223 through the bore 209 of the holder 102 and through the one-way valve 221. The piston assembly 222 may be disposed within the bore 209 such that as more lubricant is inserted into the bore 209, the piston assembly 222 may compress to allow the lubricant to be inserted. After the lubricant is inserted into the bore 209, the piston assembly 222 may apply pressure on the lubricant, which may force it up around the shank assembly 200 and out of the holder 102. This may allow the pick 101 to rotate more easily and may decrease friction while the pick rotates for better wear protection of areas in contact with the holder 102, such as the base 204 of the bolster 205 and the shank assembly 200.
A weeping seal may be disposed around the shank assembly 200 such that it is in contact with the shank assembly 200, the bolster 205, and the holder 102, which may limit the rate at which the lubricant is expelled from the bore 209. The lubricant may also be provided from the driving mechanism. In embodiments, where the driving mechanism 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 assembly 200 or the bore 209 of the holder 102 to aid in exposing the surfaces or the shank and the holder bore to the lubricant. In some embodiments, the lubricant is added to the bore 209 of the holder 102 prior to securing the shank assembly 200 within the holder 102. In such an embodiment, the insertion of the shank assembly 200 may penetrate the volume of the lubricant forcing a portion of the volume to flow around the shank and also compressing the lubricant within the bore.
Dimensions of the shank assembly 200 and bolster 205 may be important to the function and efficiency of the pick 101. A ratio of a length 219 of the shank assembly 200 to a length 225 of the bolster 205 may be from 1.75:1 to 2.5:1. A ratio of a maximum width of the bolster 205 to the outer diameter 216 of the shank assembly 200 may be from 1.5:1 to 2.5:1. The first end 201 of the shank assembly 200 may be fitted into the cavity 203 of the bolster 205 to a depth of 0.300 to 0.700 inches. The cavity 203 of the bolster 205 may comprise a depth from 0.600 to 1 inch. The shank assembly 200 may or may not extend into the full depth 305 of the bore 203. The shank assembly 200 and bolster 205 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 405 of the cavity 203 and an outside surface of the bolster 205 of 0.200 inches, preferable at least 0.210 inches. Reducing the volume of the bolster 205 may advantageously reduce the cost of the pick 101.
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 of the superhard material may form an included angle with a central axis of the tip between 30 to 60 degrees. In asphalt milling applications, the inventors have discovered that an optimal included angle is 45 degrees, whereas in mining applications the inventors have discovered that an optimal included angle is between 35 and 40 degrees. A tip 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.
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In
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When the first end 201 of the shank assembly 200 is inserted into the cavity 203, the locking head 1703 may be extended away from the constricted inner diameter 901 of the shank assembly 200. 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 901. The insertable locking mechanism 1701 may comprise an elastomeric material and may be flexible. In some embodiments the insertable locking mechanism may comprise a metal and/or a flexible metal. The insertable locking mechanism 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 203. 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 201 of the shank assembly 200 may be further inserted into the cavity 203 of the bolster 205. Once the shank assembly 200 is inserted into the cavity 203 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 901. This contact and further threading of the nut 1706 on the locking shaft 1702 may cause the locking shaft 1702 to move toward the second end 202 of the shank assembly 200 in a direction parallel to the central axis 403 of the assembly 200. 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 405 of the bolster 205.
Once the nut 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 exit the opening 1710. In some embodiments the contact between the locking head 1703 and the bolster 205 via the insertable locking mechanism 1701 may be sufficient to prevent both rotation of the shank assembly 200 about its central axis 403 and movement of the shank assembly in a direction parallel to its central axis 403. In the present embodiment the attachment mechanism 214 is also adapted to inducibly release the shank assembly 200 from attachment with the carbide bolster 205 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.
This application is a continuation-in-part of U.S. patent application Ser. No. 11/844,586 filed on Aug. 24, 2007. U.S. patent application Ser. No. 11/844,586 is a continuation-in-part of U.S. patent application Ser. No. 11/829,761, which was filed on Jul. 27, 2007. U.S. patent application Ser. No. 11/829,761 is a continuation-in-part of U.S. patent application Ser. No. 11/773,271 which was filed on Jul. 3, 2007. U.S. patent application Ser. No. 11/773,271 is a continuation-in-part of U.S. patent application Ser. No. 11/766,903 filed on Jun. 22, 2007. U.S. patent application Ser. No. 11/766,903 is a continuation of U.S. patent application Ser. No. 11/766,865 filed on Jun. 22, 2007. U.S. patent application Ser. No. 11/766,865 is a continuation-in-part of U.S. patent application Ser. No. 11/742,304 which was filed on Apr. 30, 2007. U.S. patent application Ser. No. 11/742,304 is a continuation of U.S. patent application Ser. No. 11/742,261 which was filed on Apr. 30, 2007. U.S. patent application Ser. No. 11/742,261 is a continuation-in-part of U.S. patent application Ser. No. 11/464,008 which was filed on Aug. 11, 2006. U.S. patent application Ser. No. 11/464,008 is a continuation-in-part of U.S. patent application Ser. No. 11/463,998 which was filed on Aug. 11, 2006. U.S. patent application Ser. No. 11/463,998 is a continuation-in-part of U.S. patent application Ser. No. 11/463,990 which was filed on Aug. 11, 2006. U.S. patent application Ser. No. 11/463,990 is a continuation-in-part of U.S. patent application Ser. No. 11/463,975 which was filed on Aug. 11, 2006. U.S. patent application Ser. No. 11/463,975 is a continuation-in-part of U.S. patent application Ser. No. 11/463,962 which was filed on Aug. 11, 2006. U.S. patent application Ser. No. 11/463,962 is a continuation-in-part of U.S. patent application Ser. No. 11/463,953, which was also filed on Aug. 11, 2006. The present application is also a continuation-in-part of U.S. patent application Ser. No. 11/695,672 which was filed on Apr. 3, 2007. U.S. patent application Ser. No. 11/695,672 is a continuation-in-part of U.S. patent application Ser. No. 11/686,831 filed on Mar. 15, 2007. All of these applications are herein incorporated by reference for all that they contain.
Number | Date | Country | |
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Parent | 11766865 | Jun 2007 | US |
Child | 11766903 | Jun 2007 | US |
Parent | 11742261 | Apr 2007 | US |
Child | 11742304 | Apr 2007 | US |
Number | Date | Country | |
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Parent | 11844586 | Aug 2007 | US |
Child | 11947644 | Nov 2007 | US |
Parent | 11829761 | Jul 2007 | US |
Child | 11844586 | Aug 2007 | US |
Parent | 11773271 | Jul 2007 | US |
Child | 11829761 | Jul 2007 | US |
Parent | 11766903 | Jun 2007 | US |
Child | 11773271 | Jul 2007 | US |
Parent | 11742304 | Apr 2007 | US |
Child | 11766865 | Jun 2007 | US |
Parent | 11464008 | Aug 2006 | US |
Child | 11742261 | Apr 2007 | US |
Parent | 11463998 | Aug 2006 | US |
Child | 11464008 | Aug 2006 | US |
Parent | 11463990 | Aug 2006 | US |
Child | 11463998 | Aug 2006 | US |
Parent | 11463975 | Aug 2006 | US |
Child | 11463990 | Aug 2006 | US |
Parent | 11463962 | Aug 2006 | US |
Child | 11463975 | Aug 2006 | US |
Parent | 11463953 | Aug 2006 | US |
Child | 11463962 | Aug 2006 | US |
Parent | 11695672 | Apr 2007 | US |
Child | 11947644 | Nov 2007 | US |
Parent | 11686831 | Mar 2007 | US |
Child | 11947644 | Nov 2007 | US |