Patent Publication Number: US-2020276591-A1

Title: Pressure plate apparatus

Description:
This application is a continuation-in-part of application Ser. No. 16/288,403, filed Feb. 28, 2019 and entitled Pressure Plate Apparatus. 
    
    
     TECHNICAL FIELD 
     Embodiments disclosed herein relate generally to cone crushers and more specifically to a system for preventing the tendency of a cone crusher head to elevated and/or to rotate. 
     BACKGROUND 
     Cone crushers are typically used to crush large rocks into smaller rocks at quarries. They include a conical crushing head that gyrates with a central shaft, the gyration of which is caused by a rotating eccentric surrounding the shaft. A hardened mantle covers the crushing head to crush rocks between it and a hardened liner of the crusher bowl in a crushing zone. The eccentric is driven by a diesel engine or electric motor power drive. 
     A cone head ball surface is typically mounted to the central shaft. This ball surface carries downward thrust loads, which it passes on to a stationary socket and thrust bearings disposed below the ball surface and socket interface. The thrust forces push the ball surface down on the stationary socket, creating friction that normally holds the shaft from rotating with the rotation of the eccentric. The downward thrust forces are anything but constant as the mantle gyrates and rocks enter and exit the crushing chamber. Without constant and substantial friction between the ball, which is mounted to the central shaft, and the stationary socket, the shaft and the mantle mounted to it may tend to rotate, which may create problems with the operation of the crusher. 
     Another drawback with some existing cone crushers is that, under particularly cold conditions, some cone crushers will exhibit what is called “cone head lift.” This phenomenon sometimes occurs during warm up of the crusher in cold weather, when the lubricating oil is especially viscous. Under these conditions, high internal fluid pressure may exceed the weight of the shaft and head, causing the head to lift. This can result in oil leakage and oil contamination, as well as damage to the oil seals. This cone head lift can be addressed by keeping a relatively constant downward pressure on the shaft, preventing the lifting even when forces generated by the thickened oil exceed the weight of the shaft and head. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments will be readily understood by the following detailed description in conjunction with the accompanying drawings and the appended claims. Embodiments are illustrated by way of example and not by way of limitation in the figures of the accompanying drawings. 
         FIG. 1  is a side elevation sectional view of a cone crusher incorporating a first embodiment of the pressure plate apparatus; 
         FIG. 2A  is an enlarged, fragmentary, sectioned perspective view of the first embodiment of the pressure plate apparatus; 
         FIG. 2B  is an enlarged, fragmentary, side elevation sectional view of the first embodiment of the pressure plate apparatus; 
         FIG. 2C  is an enlarged, fragmentary, sectioned perspective view of the first embodiment of the pressure plate apparatus, with the surrounding structure of the crusher deleted for illustrative purposes; 
         FIG. 3  is a perspective view of an upwardly-facing side of the pressure plate of the first embodiment; 
         FIG. 4  is a side elevation sectional view of the pressure plate of the first embodiment; 
         FIG. 5  is a perspective view of an end cap of the first embodiment, looking from an upper angle; 
         FIG. 6  is a side elevation, partially sectioned view of the end cap of the first embodiment, showing a nut and cotter pin threaded to a lower end of the end cap; 
         FIG. 7  is a perspective view of a thrust washer disc of the first embodiment, looking from an upper angle 
         FIG. 8  is a perspective, sectioned view of a thrust washer disc of the first embodiment; 
         FIG. 9  is a side elevation sectional view of the first embodiment of the thrust washer disc depicted in  FIGS. 7 and 8 ; 
         FIG. 10  is a perspective, sectioned view of a Belleville washer that may be used with the first embodiment; 
         FIG. 11  is a perspective, sectioned view of a housing that may be incorporated into the first embodiment, showing, among other things, an annular gap in which the Belleville washer(s) may be positioned; 
         FIG. 12  is a perspective view of the underside of the housing of  FIG. 11 ; 
         FIG. 13  is a side elevation sectional view showing the interaction of the pressure plate with the thrust washer disc of the first embodiment; and 
         FIG. 14  is a fragmentary side elevation sectional view of a second embodiment of the pressure plate system; 
         FIG. 15  is a perspective view of the end cap of the second embodiment; and 
         FIG. 16  is a fragmentary side elevation sectional view of a third embodiment showing a pressure plate wear insert abutting the thrust washer disc. 
     
    
    
     DETAILED DESCRIPTION OF DISCLOSED EMBODIMENTS 
     In the following detailed description, reference is made to the accompanying drawings which form a part hereof, and in which are shown by way of illustration embodiments that may be practiced. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope. Therefore, the following detailed description is not to be taken in a limiting sense. 
     Various operations may be described as multiple discrete operations in turn, in a manner that may be helpful in understanding embodiments; however, the order of description should not be construed to imply that these operations are order-dependent. 
     The description may use perspective-based descriptions such as up/down, back/front, and top/bottom. Such descriptions are merely used to facilitate the discussion and are not intended to restrict the application of disclosed embodiments. 
     The terms “coupled” and “connected,” along with their derivatives, may be used. It should be understood that these terms are not intended as synonyms for each other. Rather, in particular embodiments, “connected” may be used to indicate that two or more elements are in direct physical or electrical contact with each other. “Coupled” may mean that two or more elements are in direct physical or electrical contact. However, “coupled” may also mean that two or more elements are not in direct contact with each other, but yet still cooperate or interact with each other. 
     For the purposes of the description, a phrase in the form “A/B” or in the form “A and/or B” means (A), (B), or (A and B). For the purposes of the description, a phrase in the form “at least one of A, B, and C” means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B and C). For the purposes of the description, a phrase in the form “(A)B” means (B) or (AB) that is, A is an optional element. 
     The description may use the terms “embodiment” or “embodiments,” which may each refer to one or more of the same or different embodiments. Furthermore, the terms “comprising,” “including,” “having,” and the like, as used with respect to embodiments, are synonymous, and are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). 
     With respect to the use of any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity. 
     One aspect of the present disclosure provides a system for maintaining a downward force on a central shaft of a cone crusher having a stationary frame, wherein the central shaft is mounted to gyrate with respect to the stationary frame. The system may include a disc fixed to the frame and having a substantially centrally-disposed opening, and a pressure plate mounted to and biased toward the central shaft and positioned below the disc, the pressure plate having a surface that faces the disc and extends downwardly, the bias of the pressure plate toward the central shaft biasing the pressure plate against the disc during at least some crushing operations, the disc exerting a downward force on the pressure plate and on the central shaft to which the pressure plate is mounted during the at least some operations. 
     When it is stated here and elsewhere in this disclosure that a surface of the pressure plate extends downwardly, this is to encompass even a slight downward extension, or a convex curvature in the surface (convex with respect to the upper portion of the crusher, or concave with respect to the bottom of the crusher). The phrase does not require that the entire pressure plate be shaped to extend downwardly—only the upper surface, although the phrase is to encompass a pressure plate configuration in which the entire plate is shaped to extend downwardly. 
     In this system, the bias may be imparted by at least one spring disposed between the pressure plate and the central shaft, and the at least one spring may be a stack of Belleville springs. The disc may also include a downwardly-facing surface that extends downwardly and faces the pressure plate. The meaning of the downwardly-facing surface of the disc extending downwardly is similar to the meaning of the phrase used in connection with the pressure plate. 
     The surface of the pressure plate facing the disc may be generally convex, and the configuration of the facing surfaces of the disc and pressure plate may complement each other. This does not mean, here or elsewhere in this disclosure, that the facing surfaces need to be identical or virtually identical but they should be similar enough that the pressure plate can slide around the disc during the gyration of the central shaft without interference that might cause overheating or damage to the pressure plate or the disc. However, in one aspect of the disclosure the shape of the downwardly-facing surface of the disc and the shape of the upwardly-facing surface of the pressure plate are the same; meaning that the contacting surfaces of the disc and the pressure plate are the same (although inverse because they face each other). 
     The system may include a housing mounted to the central shaft and an end cap mounted to the pressure plate, with the at least one spring disposed between the housing and the end cap, which may be slidably mounted to each other. 
     The end cap and the central shaft may be slidably mounted to each other, and end cap may extend upwardly into the central shaft. 
     The pressure plate may include a replaceable wear insert facing the disc that may be replaced when it is desired to change the configuration of the pressure plate or when the wear insert becomes worn. 
     Another aspect of the disclosure is a pressure plate apparatus for mounting to a gyrating central shaft in a cone crusher having a stationary frame, the pressure plate apparatus including a pressure plate that provides a downward force on the central shaft during at least some crushing operations. The apparatus may include a housing mounted to an underside of the central shaft, and an end cap mounted to the pressure plate and slidably mounted to the housing. At least one spring may be positioned between the housing and the end cap to bias the pressure plate toward the central shaft. A disc may be fixed to the stationary frame and disposed above the pressure plate, the disc having a centrally-disposed opening. The pressure plate may gyrate with the central shaft, with the disc exerting a downward force on the at least one spring, the pressure plate and the central shaft. In this aspect of the disclosure, the pressure plate and the disc extend downwardly in generally convex configurations. 
     Another aspect of the disclosure is a process for maintaining downward pressure on the cone of a cone crusher having a stationary frame, a central shaft, and an eccentric that gyrates the central shaft with respect to the frame. The process may include the following steps, not necessarily in the order recited: selecting a pressure plate having a downwardly-extending upwardly-facing surface; positioning at least one spring between the central shaft and the pressure plate; fixing a disc to the frame, the disc having a downwardly-extending and downwardly-facing surface and a substantially centrally-disposed opening; mounting the pressure plate to the central shaft such that the upwardly-facing surface of the pressure plate faces the downwardly-facing surface of the disc, the at least one spring exerting an upward bias on the pressure plate toward the disc, with the disc exerting a downward force on the pressure plate and the central shaft during at least a portion of the time the crusher is performing crushing operations. 
     Another aspect of the disclosure provides a process for maintaining downward pressure on the cone of a cone crusher having a stationary frame, a central shaft, a first and a second thrust bearing surface mounted to the central shaft that absorb at least some downward thrust during crushing operations, and a rotating eccentric that gyrates the central shaft with respect to the frame. The process may include the following steps, not necessarily in the order recited: mounting a housing to the central shaft; positioning at least one spring adjacent the housing; slidably mounting an end cap to the housing such that the at least one spring is disposed between the housing and the end cap; fixing a disc to the frame, the disc having a substantially centrally-disposed opening, and a generally convex downwardly-facing surface; selecting a plate having a generally convex upwardly-facing surface; and mounting the plate to the end cap such that the disc is disposed between the plate and central shaft and the at least one spring biases the plate toward the disc so that when crushing operations are initiated, the disc and the plate will exert a downward force on the central shaft and the plate will gyrate with the central shaft and with respect to the disc. This process may also include causing any debris disposed between the pressure plate and the disc to move radially outwardly until it drops off the pressure plate. 
     Another aspect of the disclosure provides a system for maintaining a downward force on a central shaft of a cone crusher having a stationary frame. The system may include a disc fixed to the frame, the disc having a substantially centrally-disposed opening. It may also include a plate mounted to the central shaft, with at least one spring disposed to exert an upward bias on the plate with respect to the central shaft. The plate and the disc are positioned against each other during at least some of the operations of the crusher so that the disc presses downwardly on the plate to exert a downward bias on the central shaft. The plate may include a replaceable wear insert facing the disc that may be replaced when it is desired to change the configuration of the plate or when the wear insert becomes worn. 
     In this latest aspect, the system may include a housing fixed to the central shaft, with the at least one spring disposed within the housing. In that embodiment an end cap may be fixed to the plate and slidably mounted to the housing, with the at least one spring disposed to exert a bias between the housing and the end cap. 
     Reference should now be made to the figures, as this description continues. Crusher  10  is largely conventional, except for the pressure plate apparatus, generally indicated at  12 , at the bottom of the crusher.  FIG. 1  shows that cone crushers include a cone head  13  and a cone head ball surface  14 , which is mounted to a central shaft  16 . Ball surface  14  is disposed immediately above and rests against a stationary socket  18 , which is mounted indirectly to the central shaft. A mantle  20  is mounted to the top of central shaft  16 , which gyrates due to the action of a surrounding, rotating eccentric  22 . The action of the gyrating mantle  20  moving toward a stationary bowl liner  22  breaks down rocks that enter a crushing zone  24  extending between the mantle and the liner. All of the foregoing components are mounted within a stationary crusher frame  26 . 
     When rocks are fed into a crushing chamber  24 , a crushing force acts on mantle  20 , pushing the mantle downward and pressing central shaft  16  against a radial bearing  28 . But most of the downward force is transmitted from central shaft  16  to ball surface  14  and stationary socket  18  and to a pair of flat, ring-type thrust bearings  30 . As described above, this downward thrust of central shaft ball surface against stationary socket  18  creates friction between the ball surface and the socket, tending to prevent central shaft  16  and mantle  20  mounted to it from rotating. However, given the substantial and widely varying thrust forces generating during crushing operations, this force and therefore the amount of friction will vary greatly, providing for the possibility that cone head ball surface  14 , central shaft  16  and mantle  20  may from time to time, rotate. 
     To counter this possibility and to provide a relatively constant amount of pressure between cone head ball surface  14  and stationary socket  18 , pressure plate apparatus  12  is provided. This relatively constant pressure is effected by providing a constant downward force on central shaft  16  using at least one spring, the operation of which will be explained as this description continues. 
       FIG. 1  shows a typical position of a pressure plate  38  in pressure plate apparatus  12 . As shown best in  FIGS. 2A-C  and  6 , pressure plate  38  is fastened to an end cap  52  by a nut  34 , which is threaded on to threads  32  at the bottom of the end cap. A cotter pin or bolt  33  ensures that nut  34  is retained in position on end cap  52 . 
     Pressure plate  38 , may be generally circular in configuration. Thrust washer disc  40  is also generally circular in configuration as shown best in  FIGS. 2A-B  and  7 - 9 , and includes a substantially centrally-disposed opening  43  that may be generally circular in shape and may be said to have a first diameter. Pressure plate  38  may be said to have a second diameter, which may be larger than the first diameter of the thrust washer disc central opening  43 . The outer periphery of thrust washer disc  40  includes a flange  42  that is bolted via bolt holes  44  to frame  26 . However, it should be understood that the substantially centrally-disposed opening of the disc may not be generally circular and it is not necessary that the second diameter of the pressure plate be larger than the first diameter of the disc opening. As shown in  FIGS. 7-9 , thrust washer disc  40  also typically includes lubrication openings  47  to facilitate lubrication between disc  40  and pressure plate  38 . An appropriate pattern of channels (not shown) may be provided in in the downwardly-facing surface  41  of disc  40  and/or in the upwardly-facing surface  37  of pressure plate  38  to spread lubrication over the interface between the disc and the pressure plate. 
       FIGS. 1, 2A -B and  13  show pressure plate  38  at one side of thrust washer disc  40 . Given that central shaft  16  is always off to one side of center, these figures illustrate a typical relative disposition of pressure plate  38  and thrust washer disc  40 . 
       FIGS. 3 and 4  illustrate that pressure plate  38  includes a raised portion  45  with an internally splined region  46 . A complementing splined region  50  in end cap  52 , is shown best in  FIGS. 5 and 6 . End cap  52  also includes a raised annular shoulder  54  and a broad platform  56 . Platform  56  may be multi-sided, with sides  58 , as shown best in  FIG. 5 . Lubrication holes  55  may be positioned in platform  56  to facilitate lubrication of the interface between shoulder  54  and the adjacent bearing, to be described below. 
     A housing  60 , shown best in  FIGS. 11 and 12 , may also be included, with at least one spring being disposed between the housing and the end cap. It is possible that a plurality of springs may be disposed in aligned holes spaced around the housing but in the depicted embodiment a plurality of slightly conically-shaped so-called Belleville washers or springs  62  are positioned in the housing. With a plurality of Belleville springs  62  included, the springs form a stack. As shown in  FIGS. 2A-C , in the preferred embodiment, springs  62  include pairs of springs mounted in alternating dispositions to provide the appropriate amount of bias. A circular spacer  63  may be disposed above the Belleville springs  62  and below platform  56  of end cap  52 . 
     The housing shown in  FIGS. 11 and 12  may be generally cylindrical but with many features designed to retain various components and fit within and between other components of pressure plate apparatus  12 . For example, housing  60  includes a cylindrical passage  64  designed to receive the raised portion  45  of pressure plate  38  as well as the central extension  50  of end cap  52 . A bushing or bearing  65  may be provided in the inner periphery of cylindrical passage  64 . The housing also includes an annular gap  66  designed to receive and retain Belleville springs  62 . Annular gap  66  does not extend entirely through housing  60  so that the springs bottom out in the housing. One or more venting openings  68  may be provided in annular gap  66 . 
     Also included in housing  60  are a plurality of bolt holes  70  evenly positioned around the periphery of the housing, provided with shoulders  72  to support the heads of bolts  74  that extend therethrough. As seen in  FIGS. 2A-C , bolts  74  serve to mount housing  60  the central shaft  16 , which, again, gyrates from side to side with the rotation of eccentric  22  but should not rotate. As shown in  FIG. 11 , flat segments  76  in housing  60  receive the flattened edges  58  of end cap  52  (see  FIG. 5 ) to ensure that the housing does not rotate with respect to the adjacent components. 
     As seen best in  FIGS. 1-2B , a shallow oil pan  78  is provided in the bottom of the crusher below the pressure plate apparatus  12 . Oil pan  78  will tend to collect lubricating oil as it drains from radial bearing  28  and an eccentric bearing  80  before draining through a drainage port (not shown) and returning to a lubricating oil reservoir (not shown). Oil flowing into pan  78  ensures that the sliding surfaces between the upper surface of pressure plate  38  and the lower surface of thrust washer disc  40  are fully lubricated and sufficiently cooled while shaft  16  gyrates from side to side and the pressure plate and thrust washer disc surfaces are sliding across each other. 
     The lubrication between the upwardly-facing surface  37  of pressure plate  38  and the downwardly-facing surface lower surface  41  of thrust washer disc  40  is further facilitated by the fact that the pressure plate may from time to time during crushing operations be moving slightly up and down with respect to the thrust washer disc, as shown by the arrows in  FIG. 2B .  FIGS. 2B and 13  depict pressure plate  38  in its upper-most position against thrust washer disc  40 . Upward and downward axial movement of pressure plate  38  is made possible by springs  62 , which provide a pulling force on central shaft  16 . This in turn ensures that there is pressure between the previously-discussed cone head ball surface  14  and stationary socket  18 , minimizing and normally preventing rotation of cone head  13  and central shaft  16 . This relatively constant pressure between ball surface  14  and socket  18  also minimizes and normally prevents any cone head lift, resulting from overly-viscous lubricating oil during start up in cold conditions. The cone head ball surface and the stationary socket may sometimes be referred to herein as a first and a second thrust-bearing surface. 
     It has been determined that in some instances if the upwardly-facing surface  37  of pressure plate  38  extends at all upwardly or is even perfectly perpendicular to central shaft  16 , debris might become lodged and trapped between pressure plate  38  and thrust washer disc  40 . To avoid this phenomenon, the upwardly-facing surface  37  of pressure plate  38  may be designed to extend downwardly. It may even take a slightly generally convex configuration with respect to central shaft  16 . In other instances (not shown) the entire pressure plate may be downwardly-extending or in some cases downwardly convex. If a radiused curvature is used for the upwardly-facing surface of pressure plate  38 , a typical radius would be about 71 inches, although this will depend on the dimensions of the crusher and the pressure plate system. 
     In many instances where upwardly-facing surface  37  is downwardly-extending or even convex, the downwardly-facing surface  41  of thrust washer disc  40  may also be downwardly-extending or, in some cases, downwardly convex. In many instances, surfaces  37  and  41  will be complementing in their downward extension or if convex, in their convex configuration. In many instances, this complementing degree of downward extension or convex-ness might be precisely the same. 
     As a result of the downwardly-extending interface between the disc and the pressure plate, any debris that is disposed between thrust washer disc  40  and the pressure plate will tend to move radially outwardly until it drops off the outer periphery of the pressure plate. This phenomenon will tend to reduce or eliminate the possibility of the pressure plate and thrust washer disc overheating due to the presence of such debris. 
     The degree of downward extension of the upwardly-facing surface  37  of pressure plate  38  and the downwardly-facing surface  41  of thrust washer disc  40  will vary depending up the particular application. However, as shown in  FIG. 13 , it has been determined that an inclination of about 4.5 degrees is ideal, with a range being something in the neighborhood of 1-10 degrees. 
     Embodiment of FIGS.  14  and  15   
     Because most of the features of the second embodiment depicted in  FIGS. 14 and 15  are identical or substantially the same as those of crusher  10  described above, the entire crusher has neither been shown nor identified. Because even the pressure plate system is largely the same as the prior embodiment  12 , corresponding numbers in the  100  series will be used for this slightly different pressure plate system  112 . 
     The difference in this second embodiment is that the end cap  152  has an upper portion  153  that extends upwardly into the central shaft  116 , which may include a bushing or bearing  167 . This means that end cap  152  includes features on both the top and bottom of broad platform  156  that provide increased stability to the end cap as it moves up and down with the action of springs  162 . Raised annular shoulder  154  continues to provide stability below platform  156  of the end cap; however, in this embodiment upper portion  153  provides an additional guide surface in central shaft  116  to ensure that end cap  152  does not tilt to one side or the other as it moves up and down. 
     As shown in  FIG. 15 , lubrication grooves  190  and  192  extend axially along annular shoulder  154  and upper portion  153 , respectively, via lubricating holes  155  and interconnecting lubrication channels (not shown). 
     Embodiment of FIG.  16   
       FIG. 16  depicts a third embodiment of the pressure plate system. Because most of the features of this variation are identical or substantially the same as the earlier embodiments, the entire crusher has not been show. As with embodiment  110 , because even the pressure plate system  212  of this second alternative embodiment is largely the same as the prior embodiment  12 , corresponding numbers in the  200  series will be used. 
     In this third embodiment  212 , the curvature and configuration of upwardly-facing surface  237  of pressure plate  238  may be modified by using a flat pressure plate  238  and mounting to it a wear liner  239 . The wear liner  239  may take a wide variety of configurations. The depicted wear liner  239  is shown to be upwardly concave, although it might alternatively be flat or upwardly convex. In any event, use of a wear liner  239  facilitates replacement when a change of configuration is desired or if upwardly-facing surface  237  becomes excessively worn. A disc  240  formed of cast iron has been found to be particularly appropriate when a bronze wear liner  239  is utilized. 
     Although certain embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a wide variety of alternate and/or equivalent embodiments or implementations calculated to achieve the same purposes may be substituted for the embodiments shown and described without departing from the scope. Those with skill in the art will readily appreciate that embodiments may be implemented in a very wide variety of ways. This application is intended to cover any adaptations or variations of the embodiments discussed herein. Therefore, it is manifestly intended that embodiments be limited only by the claims and the equivalents thereof.