Patent Publication Number: US-10773259-B2

Title: Eccentric assembly for gyratory or cone crusher

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is the U.S. national stage application of International Application PCT/IB2016/054964 filed Aug. 19, 2016, which international application was published on Mar. 2, 2017, as International Publication WO 2017/033103 in the English language. The International Application claims priority of European Patent Application 15182030.5, filed Aug. 21, 2015. 
     FIELD OF THE INVENTION 
     The present invention relates to an eccentric assembly for use in a gyratory crusher or cone crusher. The invention also relates to a crusher including such an eccentric assembly, and to a counterweight assembly for use in such an eccentric assembly and/or such a gyratory or cone crusher. 
     Cone crushers and gyratory crushers are two types of rock crushing systems, which generally break apart rock, stone or other material in a crushing gap between a stationary element and a moving element. A cone or gyratory crusher is comprised of a head assembly including a crushing head that gyrates about a vertical axis within a stationary bowl attached to a main frame of the rock crusher. The crushing head is assembled surrounding an eccentric that rotates about a fixed shaft to impart the gyratory motion of the crushing head which crushes rock, stone or other material in a crushing gap between the crushing head and the bowl. The eccentric can be driven by a variety of power drives, such as an attached gear, driven by a pinion and countershaft assembly, and a number of mechanical power sources, such as electrical motors or combustion engines. 
     The gyratory motion of the crushing head with respect to the stationary bowl crushes rock, stone or other material as it travels through the crushing gap. The crushed material exits the cone crusher through the bottom of the crushing gap. 
     During operation of a cone or gyratory crusher, the gyratory movement of the head assembly and mantle and the offset rotation of the eccentric create large, unbalanced forces. 
     PRIOR ART 
     In an attempt to compensate for the large, unbalanced forces generated during operation of a cone or gyratory crusher, a counterweight assembly has been connected to the eccentric for rotation therewith. 
     In some of the prior art solutions, the counterweight is, however, far from the center of gravity of the moving parts within the crusher, so that a bending effect remains which affects the main shaft of the crusher. 
     US 2012/0223171 A1 relates to a counterweight assembly for use in a cone crusher. In general, the counterweight assembly rotates along with an eccentric about a fixed main shaft in the cone crusher. The counterweight assembly provides balance for the offset rotation of the eccentric and the gyratory movement of the head assembly and mantle. The counterweight assembly is mounted for rotation with the eccentric and includes a counterweight body having a generally annular shape. The counterweight body of the counterweight assembly in one embodiment includes both a weighted section and an unweighted section that are joined to each other to define the generally annular shape for the casting. The counterweight ring is arranged so as to surround the eccentric, thereby adding to the radial dimensions of the crusher. 
     SUMMARY OF THE INVENTION 
     In view of the above, the present invention provides an eccentric assembly for use in a gyratory or cone crusher as recited in claim  1 . 
     The gyratory or cone crusher, in which the eccentric assembly of the invention is used, comprises a main shaft having a longitudinal extension along a central axis of the crusher, a head assembly including a crushing head provided with a first crushing shell, and a frame provided with a second crushing shell, wherein the first and second crushing shells between them define a crushing gap. The eccentric assembly is provided with an inner circumferential surface and an outer circumferential surface eccentrically arranged relative to the inner circumferential surface, wherein the inner circumferential surface of the eccentric assembly is arranged for being journalled to the main shaft so that the eccentric assembly is adapted to rotate about said central axis, and wherein the outer circumferential surface of the eccentric assembly is arranged for being journalled to the crushing head. 
     In accordance with the invention, the eccentric assembly includes a first eccentric part and a second eccentric part which is configured for being located at a distance from the first eccentric part in a direction along the central axis. 
     By providing first and second eccentric parts spaced apart from each other in a direction along the central axis, the arrangement of the eccentric assembly becomes more flexible and can be suitably adjusted so as to obtain an optimum movement of the crushing head in view of a desired crushing pattern. 
     The eccentric assembly can further be provided with an intermediate element arranged between the first eccentric part and the second eccentric part in a direction along the central axis. This intermediate element has either a non-eccentric shape or at least an eccentricity which is different from the eccentricity of the first and second eccentric parts. The gyratory movement of the head assembly is thereby imposed by the first and second eccentric parts of the eccentric assembly, whereas the intermediate element is disposed between the two eccentric parts. 
     The intermediate element is preferably is coupled to the first and/or the second eccentric parts so as to rotate together therewith. The intermediate element can either be formed in one piece with the first and/or the second eccentric part, or formed separate from and coupled with the first and/or the second eccentric part. 
     The intermediate element can be configured as a sleeve-type element surrounding the main shaft, preferably with a gap between the outer circumference of the main shaft and the inner circumference of the sleeve-type intermediate element. The shape of the intermediate element thereby essentially follows the shape of the main shaft. In some embodiments, the intermediate element is therefore essentially cone shaped. The intermediate element may also have at least two sections having different inclinations relative to the central axis, in particular if the main shaft is also configured accordingly. 
     The eccentric assembly can further be provided with a counterweight assembly including a counterweight body, the counterweight assembly being configured to rotate together with the eccentric assembly and compensate for the unbalanced forces generated by the gyratory movement of the head assembly and the offset rotation of the eccentric parts. 
     In order to provide for the counterweight assembly to rotate together with the eccentric assembly, the counterweight assembly is preferably coupled with the eccentric assembly. 
     By locating the counterweight body between the first and the second eccentric parts in the direction along the central axis, it is possible to align the load and counterbalance load, reducing or eliminating the bending effect, without increasing the radial dimensions of the cone or gyratory crusher as a whole. 
     The counterweight body may have at least in part a cylindrical outer surface, preferably in a lower section of the counterweight body. Alternatively or in addition, the counterweight body may have at least in part a tapered outer surface, preferably in an upper section of the counterweight body. The counterweight body may have at least two sections as seen in the direction along the central axis, the outer circumferential surfaces of which have different inclinations relative to the central axis. In any one of these embodiments, the shape of the counterweight is designed so as to obtain a desired mass distribution and center of gravity of the counterweight assembly. 
     The circumferential location of the counterweight is suitably chosen so as to compensate for the forces imparted by the eccentric surfaces of the two eccentric parts during rotation of the eccentric: a weighted section of the counterweight can be generally opposite the wide portion of the eccentric while an unweighted section is generally opposite the thin portion of the eccentric. 
     In embodiments in which the eccentric assembly includes an intermediate element as described above, which has e.g. the form of a sleeve and extends between the first and second eccentric parts, the counterweight body may suitably be coupled with the intermediate element. The counterweight body may be formed in one piece with the intermediate element, or the counterweight body may be formed separate from and coupled with the intermediate element, e.g. by welding. The assembly of the two eccentric parts, the intermediate element extending there between, and the counterweight body attached to the intermediate element are thereby arranged so as to rotate together. 
     If the counterweight body has at least in part a tapered outer surface, preferably in an upper section of the counterweight body, the taper of the counterweight body may also follow a taper of the intermediate element. 
     The present invention also provides a gyratory or cone crusher as recited in claim  13 . 
     The gyratory or cone crusher may further comprise a counterweight assembly including a counterweight body, the counterweight assembly being configured so as to compensate for unbalanced forces generated by the gyratory movement of the head assembly and the offset rotation of the eccentric assembly. The counterweight body may be located between the upper and the lower eccentric parts as seen in the direction along the central axis. The counterweight assembly may be configured and arranged so that the center of gravity thereof is arranged essentially at the same vertical height as the center of gravity of the eccentric assembly and head assembly together, and diametrically opposite thereto. 
     Finally, the present invention provides a counterweight assembly for use in an eccentric assembly and/or in a gyratory or cone crusher according to the invention, the counterweight assembly being configured so as to compensate for unbalanced forces generated by the gyratory movement of the head assembly and the offset rotation of the eccentric assembly of the gyratory or cone crusher. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above, as well as additional objects, features and advantages of the present invention will be better understood through the following illustrative and non-limiting detailed description of preferred embodiments of the present invention, with reference to the appended drawing, where the same reference numerals will be used for similar elements, wherein: 
         FIG. 1  shows schematically a gyratory crusher according to a first embodiment, 
         FIG. 2  is a partial enlargement of an eccentric assembly, and 
         FIG. 3  shows schematically a gyratory crusher according to a second embodiment. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       FIG. 1  schematically illustrates a gyratory crusher  1  in section. The gyratory crusher  1  has a vertically extending main shaft  2  and a frame  4 . The shaft  2  has a longitudinal axis coinciding with a central axis A of the crusher. 
     An eccentric assembly is provided, which includes a first and a second eccentric part which in the present embodiment are constituted by a first, upper and a second, lower eccentric ring  10 ,  11 . The eccentric parts or rings  10 ,  11  are rotatably supported about the shaft  2  by means of two rotational shaft bearings, which in the present embodiment are configured by rotational slide bushings,  20  and  21 . Each of the two eccentric rings  10 ,  11  is provided with a first or inner circumferential surface  10   a ,  11   a  (cf.  FIG. 2 ) and a second or outer circumferential surface  10   b ,  11   b  (cf.  FIG. 2 ) which is eccentrically arranged relative to the first circumferential surface  10   a ,  11   a.    
     A crusher head  12  is radially supported by and rotatable about the eccentric rings  10 ,  11  via another pair of rotational bearings, in this case also rotational slide bushings,  30  and  31 . Together, the shaft bearings  20 ,  21  and the head bearings  30 ,  31  form an eccentric bearing arrangement for guiding the crushing head  12  along a gyratory path. 
     A drive shaft  14  is connected to a drive motor and is provided with a pinion  15 . The drive shaft  14  is arranged to rotate the lower eccentric ring  11  by the pinion  15  engaging a gear rim  16  mounted on the lower eccentric ring  11 . 
     When the drive shaft  14  rotates the lower eccentric ring  11 , during operation of the crusher  1 , the crushing head  12  mounted thereon will execute a gyrating movement. 
     An inner crushing shell  13 , also designated a mantle, is mounted on the crushing head  12 . Crushing head  12  and mantle  13  are parts of an overall head assembly. An outer crushing shell  5 , also designated a bowl, is mounted on the frame  4 . A crushing gap  24  is formed between the two crushing shells  13 ,  5 . When the crusher  1  is operated, material to be crushed is introduced in the crushing gap  24  and is crushed between the mantle  13  and the bowl  5  as a result of the gyrating movement of the crushing head  12 , during which movement the mantle  13  approaches the outer one  5  along a rotating generatrix and moves away therefrom along a diametrically opposed generatrix. 
     As shown in  FIG. 2 , the upper head bearing  30  has a diameter D 1 , which is defined as the diameter of the outer slide surface of the upper eccentric ring  10  at the upper head bearing  30 . The lower head bearing  31  has a diameter D 2 , which is defined as the diameter of the outer slide surface of the lower eccentric ring  11  at the lower head bearing  31 . In the disclosed embodiment the two outer diameters D 1  and D 2  are different, the diameter D 1  being smaller than the diameter D 2 . In an alternative embodiment the two outer diameters D 1  and D 2  are equal. In yet another embodiment the diameter D 1  is larger than the diameter D 2 . 
     The upper shaft bearing  20  has a diameter D 3 , which is defined as the diameter of the inner slide surface of the upper eccentric ring  10  at the upper shaft bearing  20 . The lower shaft bearing  21  has a diameter D 4 , which is defined as the diameter of the inner slide surface of the lower eccentric ring  11  at the lower shaft bearing  21 . In the disclosed embodiment the two inner diameters D 3  and D 2  are different, with the inner diameter D 3  being smaller than the inner diameter D 4 . Of note, this also results in the main shaft  2  having a larger diameter in the area of the lower eccentric ring  20  and a smaller diameter in the area of the upper eccentric ring  10 , with a cone-shaped section there between. In an alternative embodiment the two inner diameters D 3  and D 4  are equal. In yet another alternative embodiment the two inner diameters D 3  and D 4  are different, with the inner diameter D 3  being larger than the inner diameter D 4 . 
     The upper and lower eccentric rings  10 ,  11  are vertically separated along the central axis A by a distance d. Between the upper and lower eccentric rings  10 ,  11 , as seen in the vertical direction, an intermediate part is provided which in the present embodiment is configured by a non-eccentric carrier sleeve  41 . At an upper end, the carrier sleeve  41  is coupled to the upper eccentric ring  10 , and at a lower end thereof, the carrier sleeve  41  is coupled to the lower eccentric ring  11 , so that the carrier sleeve  41  and eccentric rings  10 ,  11  rotate in unison about the main shaft  2 . 
     Of note, the intermediate element or carrier sleeve  41  must not necessarily be non-eccentric, but any eccentricity thereof at least differs from the eccentricity of the first and second eccentric rings  10 ,  11 . 
     The carrier sleeve  41  in turn is part of a counterweight assembly  40 . The counterweight assembly  40  further includes a counterweight body  42  assembled to an outer circumferential surface of the carrier sleeve  41 . The counterweight assembly  40  is designed to provide balance for the offset rotation of the eccentric rings  10 ,  11  about the stationary main shaft  2  and the gyratory motion of the crushing head  12  and mantle  13 . 
     Referring now to  FIG. 2 , there shown is one embodiment of the counterweight assembly  40  of the present invention. As illustrated in  FIG. 2 , the counterweight assembly  40  is made up from a carrier sleeve  41  and the counterweight body  42  as such, which is a cast component in the present embodiment, but other methods of forming the counterweight body  42  are contemplated as being within the scope of the present disclosure. The carrier sleeve  41  is a thin walled structural part which is generally cone shaped in the present embodiment, the cone shape of the carrier sleeve  41  following the cone shape of the main shaft  2  or the conical section thereof, respectively. The counterweight body  42  is attached to the carrier sleeve  41  so as to form a weighted section of the counterweight assembly  40  which is generally opposite the wide portions of the eccentric rings  10 ,  11 , whereas the unweighted section of the counterweight assembly  40 —i.e. that part of the carrier sleeve  41  which does not carry the counterweight body  42 —is generally opposite the thin portions of the eccentric rings  10 ,  11 . The counterweight body  42  may be attached to the carrier sleeve  41  e.g. by welding, or by means of bolts, pins or rivets. 
     The counterweight body  42  could be made from any suitable material, e.g. steel, cast iron, lead, or depleted uranium. The counterweight body  42  could be made from the same material as the eccentric rings  10 ,  11 , or—in particular if space is limited—from a material which has a higher density than the material used for the eccentric rings  10 ,  11 . 
     To achieve optimum balance conditions, the mass and center of gravity of the eccentric assembly and head assembly taken together should be offset by the mass and center of gravity of the counterweight assembly  40 . In order to determine a proper shape and location for the counterweight body  42 , the mass and center of gravity of the moving parts within the crusher, i.e. the head assembly (including the crusher head  12 , the mantle  13  mounted thereon, and the associated seals and bushings) and the eccentric assembly are therefore calculated first. The shape of the counterweight body  42  is then designed so that the counterweight assembly  40  compensates for the mass eccentricity of the eccentric assembly and the head assembly. The eccentric assembly, counterweight assembly and head assembly are thereby balanced to produce no net horizontal forces on the foundation. The forces and moments acting on the main shaft during crusher operation are balanced, thereby permitting smooth and relatively vibration free operation of the crusher. 
     In order to achieve this balancing of forces, the counterweight assembly  40  is configured and arranged so that with respect to the vertical position, the center of gravity of the counterweight assembly  40  is located as closely as possible to the center of gravity of the eccentric and head assemblies taken together, while the center of gravity of the counterweight assembly  40  is located diametrically opposite the center of gravity of the eccentric and head assemblies as seen in the radial direction. In order to locate the center of gravity of the counterweight body  42  accordingly, the carrier sleeve  41  and counterweight body  42  are specifically configured. In the present embodiment, the carrier sleeve  41  is generally cone shaped. The counterweight body  42  has lower section with a cylindrical outer surface and an upper section with a tapered outer surface, the taper substantially following a taper of the carrier sleeve. Of note, the shape of the counterweight body  42  can be arbitrarily chosen as long as the shape suitably provides the required center of gravity of the counterweight assembly, and as long as the counterweight fits in the available space. 
     Of note, the counterweight assembly  40  must not necessarily perfectly compensate for the forces created by the offset rotation of the eccentric rings  10 ,  11  about the stationary main shaft  2  and the gyratory motion of the crushing head  12 . Furthermore, the mantle  13  is subject to wear, so that the center of gravity of the moving parts changes over time. In order to take this wear into account, the counterweight assembly  40  can e.g. be designed for the case that the mantle  13  is half worn, so as to maintain balance over a certain time frame. 
       FIG. 3  illustrates an alternative embodiment which differs from the embodiment of  FIGS. 1 and 2  in that the non-eccentric carrier sleeve  41  of the counterweight assembly  40  is formed integrally with the upper  10  and lower eccentric rings  11 , rather than welded thereto. 
     The crusher of  FIG. 3  further differs from the one of  FIGS. 1 and 2  in that the carrier sleeve  41  has two sections having different inclinations relative to the central axis A, again following a corresponding shape of the main shaft  2 . Also in the embodiment of  FIG. 3 , the counterweight body  42  has two sections, the outer circumferential surfaces of which have different inclinations relative to the central axis A. 
     While the embodiments described above relate to a stationary crusher, the solution according to the present invention is also applicable to mobile crushing plants. As explained above, the provision of the first and second eccentric parts according to the present invention allows for an improved balancing of the moving parts within the crusher, which in turn can reduce the resonance vibrations. This can be particularly advantageous for mobile equipment which has a less rigid support than a stationary crusher.