Abstract:
A gyratory crusher uses a new head nut attachment apparatus. The gyratory crusher has a shell, a shaft disposed within the shell, a mantle covering a portion of the shaft, a head nut located above the mantle, and a sleeve between the head nut and the shaft. The sleeve is maintained in position on the shaft by means of a tapered contact surface between the sleeve and the shaft, and the head nut is threaded onto the sleeve.

Description:
FIELD OF THE INVENTION 
     This invention relates to rock crushing systems, such as conical rock crushers or gyratory crushers. Specifically, this invention elates to the main shaft assembly and head nut system. 
     BACKGROUND OF THE INVENTION 
     Gyratory rock crushers generally have a downwardly expanding central conical member which rotates or gyrates within an outer upwardly expanding frustroconically shaped member typically called a shell. The shell can be comprised of two or more pieces, e.g., a top shell and a bottom shell. The central conical member generally has a wearing cover or a liner called a mantle. A spider assembly rests on the top shell, forming the top of the support structure for the machine. 
     A shaft extends vertically through the rock crusher. This shaft is supported by a bearing in the spider assembly. The central portion of the shaft tapers inwardly in an upward direction to form the central conical crushing member. This portion of the shaft supports the mantle, which moves with the shaft to effect the crushing operation. The spider assembly is designed to support the shaft while allowing gyratory movement during operation of the machine. Additionally, the vertical position of the shaft is controlled by a piston arrangement in the spider. 
     A head nut, attached to a sleeve disposed about the shaft is used to retain the mantle in place. The head nut resists upward forces from the mantle, which tends to move in an upward direction during crusher operation. The head nut is also subject to wear from the operation of the machine, as well as damage from impacts due to the rocks being dumped into the machine from above. The head nut is disposable, but the threads used to secure the head nut to the shaft may become damaged as well. If the threads are stressed out of shape due to operation, suffer fatigue failures such as cracking of the threads, or are damaged due to impacts from falling material on the head nut, repairs can be expensive. Repairing damaged threads on the shaft may include removing the shaft from the machine to be refurbished. The repair operation is costly both because of the cost of reworking the shaft as well as the cost of machine down time while the shaft is being repaired. Accordingly, the crushing system is designed so that the shaft of the crusher is preserved from being repaired in favor of other components which may be more easily repaired or replaced, such as a sleeve. 
     A design that does not require threads on the shaft results in a smooth shaft with a resultant lower incidence of failure. Sleeves are sometimes used between the shaft and the head nut to avoid the use of threads directly on the shaft, but the sleeves may require complicated arrangements to be secured in a vertical direction with respect to the shaft. Also, split sleeves that are sometimes used require fasteners for installation. Preferably, the sleeve and head nut are compact and replaceable in case of damage or maintenance needs. The presence of additional fasteners on the sleeve or head nut complicates assembly, removal, and maintenance. 
     Therefore, it would be advantageous to have a sleeve and head nut arrangement that does not require threads on the shaft. Further, there is a need for a head nut assembly that is self-tightening in response to upward loads. Further still, there is a need for a compact and easily replaceable sleeve and head nut arrangement that does not require additional fasteners. 
     SUMMARY OF THE INVENTION 
     An exemplary embodiment relates to an attachment apparatus for a gyratory crusher including a shaft and a mantle disposed about the shaft. The attachment apparatus has a sleeve disposed about the shaft defining a contact surface between the sleeve and the shaft and a head nut threaded onto the sleeve. The radius of the shaft increases in an upward direction over at least part of the contact surface, whereby the head nut retains the mantle with respect to the shaft in at least one direction. 
     Another embodiment relates to an attachment apparatus for a gyratory crusher including a shaft and a mantle disposed about the shaft. The attachment apparatus has a sleeve disposed about the shaft and a head nut threaded onto the sleeve. The sleeve is a continuous ring, whereby the head nut prevents upward motion of the mantle. 
     Still another embodiment relates to a gyratory crusher having a shell, a shaft disposed within the shell, a mantle covering a portion of the shaft, a head nut located above the mantle, and a sleeve between the head nut and the shaft. The sleeve is maintained and positioned on the shaft by means of a tapered contact surface between the sleeve and the shaft. 
     A still further embodiment relates to a method of assembling or repairing a gyratory crusher. This method includes heating a sleeve, placing the sleeve over a shaft, cooling the sleeve to effect a shrink fit arrangement on the shaft, and threading a head nut onto the sleeve. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will hereafter be described with reference to the accompanying drawings, wherein like reference numerals denote like elements, and: 
     FIG. 1 is a vertical cross-sectional view of the gyratory crusher; and 
     FIG. 2 is a partial vertical cross-sectional view of a portion of the gyratory crusher shaft. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIG. 1, a gyratory crusher  10  can be utilized to crush rock, ore, minerals, waste, or other material. Gyratory crusher  10  is assembled on a cast steel base or bottom shell  12  having a central hub  14 . Central hub  14  is provided with a vertical bore  18  adapted to receive a cylindrical support shaft  20 . This shaft  20  varies in cross section, but extends through the machine into the spider  46 . Drive housing  13  extends outwardly from hub  14  to enclose a drive mechanism  22 . Drive mechanism  22  causes rotation of an eccentric  24  which directs the gyratory motion of the shaft  20 . 
     A head assembly  26 , which is part of the shaft  20 , includes a head member  30  which is covered by a mantle  34 . Mantle  34  provides one of the crushing surfaces of crusher  10 . At an upper portion of the head member  30 , above the mantle  34 , the shaft  20  has an outwardly tapered segment  70 . A sleeve  72  surrounds this outwardly tapered segment  70  and a head nut  76  is threaded onto the sleeve  72 . The head nut  76  resists the upward force of the mantle  34  at an interface  80  between the two components. 
     A top shell  36  projects upwardly from bottom shell  12  and is covered by a spider assembly including a spider  46 . Alternatively, top shell  36  and bottom shell  12  can be a single piece component. Spider  46  includes an aperture  40  that receives a piston  41  and an end  42  of shaft  20 . 
     Top shell  36  is protected from wear by several rows of concaves  62 . These concaves  62  provide the crushing surface opposing mantle  34 . Spider  46  can be attached or rest upon top shell  36 . Preferably top shell  36  includes a recessed portion  92  for receiving a flange  94  of spider  46 . Vertical positioning of shaft  20  with respect to top shell  36  adjusts the relative position of concaves  62  with respect to the mantle  34  of the head member  30 , thereby adjusting the size of the crushed material exiting crusher  10 . 
     Material to be crushed is supplied through spider  46  which includes openings (not shown) for entry of the material into crushing cavity  50 . A liquid flush apparatus (not shown) may be provided for spraying a liquid such as water toward the crusher cavity  50 . 
     The spider  46  is comprised of spider arms  52  radially extending outward from the center to a spider rim (not shown). A spider cap  54  sits on the top center of the spider  46 . Each of the spider arms  52  is protected from falling material by a spider arm guard  56 . The spider rim is protected by a rim liner (not shown), also known as a hopper liner. 
     Referring now to FIG. 2, the structure associated with the sleeve  72  and head nut  76  is shown. The mantle  34  has a tendency to move upward during crusher operation. Thus, the head nut  76  is used to retain the mantle  34  in place. In turn, the head nut must be secured vertically with respect to the shaft  20 . To accomplish this, a sleeve  72  is fixed to segment  70  of the shaft  20 , and the head nut  76  is attached to the sleeve  72 . In a preferred embodiment, the head nut  76  is located about 40 inches from top of shaft  20 , and is concentric with the outside diameter of the sleeve  72 . 
     In a preferred embodiment, the segment  70  begins at a point  73 , located about 47 inches from top of the shaft  20 . This shaft  20  increases in diameter in an upward direction in segment  70 , a taper of 1:315 from vertical. This is in contrast to the inward taper of the shaft  20  below the upper segment  70  of 1:8.2. The inner diameter of the sleeve  72  matches the 1:315 taper, and therefore is prevented from moving in an upward direction by the increasing diameter. The sleeve  72  is heated and shrunk onto the shaft  20  so no further fastening means are required. The fit between the sleeve  72  and segment  70  is snug once the sleeve  72  is shrunk onto segment  70 . Alternatively, the sleeve  72  could have a V-shaped inner wall, fitting into a corresponding shape on segment  70 . 
     In a preferred embodiment, the sleeve  72  is a ring that at the top portion has an inner diameter of 25.00 inches and an outer diameter of 26.9 inches and at the bottom portion has an inner diameter of 24.95 inches and an outer diameter of 26.9 inches. This creates the taper of 1:315 from vertical. The exterior of the sleeve  72  has sleeve threads  74 . The threads  74  are American National-Right Hand 0.5 inch pitch. The sleeve  72  is made of steel. The inner surface of the sleeve  72  is a smooth fit with segment  70 . 
     The head nut  76  retains the mantle  34  from moving upward during crusher operation by direct resistance at an interface  80  between the two components. The head nut  76  is made of steel and is threaded onto the sleeve  72 . Thus, the head nut  76  has threads  78  matching the sleeve threads  74 . The outer diameter of the head nut  76  is 31.3 inches in a preferred embodiment. Because the head nut  76  is threaded onto the sleeve  72  rather than the shaft  20 , the upward load is transmitted through the threads to the sleeve  72 , removing stress concentrations from the shaft  20  because the shaft  20  does not have threads. Additionally, if the upward load causes damage to the sleeve threads  74  or head nut threads  78  or either one of those members  72  or  76 , those parts may be more easily repaired or replaced than the shaft  20 . 
     The sleeve  72  requires no fasteners for installation because it is heat shrunk onto the shaft as one continuous ring. Additionally, because of the reverse taper of segment  70 , the sleeve  72  and head nut  76  arrangement is self-tightening in responds to upward loads from the mantle  34 . Also, the reverse taper structure removes the necessity of having additional structural members above the sleeve  72  or head nut  76  to retain those members in a stable vertical position with respect to the shaft  20 . 
     The gyratory crusher  10  operates as follows. When the drive mechanism  22  is driven by any appropriate means, it transmits power to the eccentric  24 . The eccentric  24  causes the gyration of the head assembly  26 , resulting in the crushing of the material in the crushing chamber  50 . The phantom lines flanking the mantle and center axis on FIG. 1 indicate the range of gyratory motion. 
     The above arrangement solves the long-standing problems discussed in the Background of the Invention section because the shrink fit of the sleeve  72  onto segment  70  allows a smooth exterior surface of the shaft  20  rather than the use of threads. The reverse taper of segment  70  and sleeve  72  resists vertical displacement of the sleeve  72  and head nut  76  in response to mantle  34  upward loads. The sleeve  72  and head nut  76  are both easily replaceable, especially because no fasteners are required to attach the sleeve  72  to the shaft  20 . Also because of the reverse taper, no further structure is required to maintain the sleeve  72  in position with respect to the shaft  20 . 
     While several embodiments of the invention have been described, it should be apparent to those skilled in the art that what has been described is considered at present to be the preferred embodiments of a sleeve  72  and head nut  76  arrangement and method of installation. However, in accordance with the patent statutes, changes may be made in the design without actually departing from the true spirit and scope of this invention. The following claims are intended to cover all such changes and modifications which fall within the true spirit and scope of this invention.