Abstract:
A comminuting apparatus for reducing the size of particles, having a frame providing an internal perimeter and having a shape; a stone having a grinding surface for grinding a material and providing a perimeter having a shape corresponding to the shape of the perimeter of the frame and configured to be at least partially surrounded by the frame; wherein when the frame is rotated the perimeter of the frame is configured to coact with the perimeter of the stone such that the stone is rotated at substantially the same rate as the frame.

Description:
This application claims the benefit of U.S. Provisional Application No. 60/149,272, filed on Aug. 17, 1999; the contents of which including title, specification, claims, and figures are incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to a grinding system in the field of comminuting devices. More particularly, the present invention relates to a mounting system for coupling a stone to a frame. 
     BACKGROUND OF THE INVENTION 
     A known method for mounting a grinding stone includes locking the stone to a backing plate via a taper, which applies a compression force or stress on the outer perimeter of the stone to hold the stone in a stationary position with respect to the backing plate. Such stress is partially counteracted by the centrifugal forces applied to the stone while in operation (i.e., rotation). Accordingly, the stone must be subjected to greater stress via the mounting taper lock than is imparted upon the stone while in operation, otherwise the stone would “spin” relative to the backing plate. 
     Another known method for mounting a grinding stone includes an arbor that extends through a center hole of the stone, which is typically threaded such that a nut can be tightened to apply a compressive force on the inner portion of the stone, thus holding it stationary with respect to the arbor. However, a problem with such known mounting methods is that significant stress must be applied to the stone before the grinder is turned on and/or are complicated, time consuming and costly. 
     SUMMARY OF THE INVENTION 
     Accordingly, it would be advantageous to substantially reduce or eliminate the pre-stress applied to a grinding stone, thereby reducing the overall stress to which the stone will be subjected while in operation. It would also be advantageous to reduce the stress applied to the stone as the rotational speed of the stone is reduced. It would also be advantageous to provide a stone mounting system made of low cost materials. It would also be advantageous to provide a mounting plate or frame that does not require removal of the stone from the grinder each time the stone is changed. It would also be advantageous to provide for a method of mounting a stone that would allow a stone that has been in operation (e.g., used) to be removed from the grinder without damaging the stone such that it can be examined, repaired, replaced or used again. It would also be advantageous to have the shape of the frame in the same shape of the mount so that the two may rotate together. It would also be advantageous to provide for stone changes that can be performed quickly. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will become more fully understood from the following detailed description, taken in conjunction with the accompanying drawings, wherein like reference numerals refer to like pans, in which: 
     FIG. 1 is an exploded perspective view of a stone mounting system according to a preferred embodiment of the present invention; 
     FIG. 2 is an exploded perspective view of the stone mounting system according to an alternative embodiment of the present invention; 
     FIG. 3 is an exploded perspective view of the stone mounting system showing a frame boss according to an alternative embodiment of the present invention; 
     FIG. 4 is an exploded perspective view of the stone mounting system showing a frame protrusion according to an alternative embodiment of the present invention; 
     FIG. 5 is an exploded perspective view of the stone mounting system showing a frame boss and a stone protrusion according to an alternative embodiment of the present invention; 
     FIG. 6 is an exploded perspective view of the stone mounting system according to an alternative embodiment of the present invention; 
     FIG. 7 is an exploded perspective view of the stone mounting system showing a stone boss according to an alternative embodiment of the present invention. 
     FIG. 8 is an exploded perspective view of the stone mounting system showing a recess configured to coact with a protrusion according to an alternative embodiment of the present invention and 
     FIG. 9 is an exploded perspective view of the stone mounting system according to an alternative embodiment of the present invention. 
     FIG. 10 is an exploded perspective view of the stone mounting system according to an alternative embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIG. 1, a stone mounting system  10  is shown according to a preferred embodiment of the present invention. System  10  includes a housing, base plate, mounting surface or backing plate (shown as a frame  20 ) coupled to an abrasive wheel (shown as a grinding stone  50 ) having a grinding surface  52  and a backing surface  54 . Frame  20  is generally circular shaped and includes an aperture  22  having a diameter  24  with multiple oblique flats  26 . The shape of the perimeter of the stone  50  approximately corresponds to the shape of the aperture  22 . (i.e., generally circular with oblique flats) Stone  50  may be inserted within aperture  22  of frame  20  such that the perimeter of stone  50  abuts against the perimeter of aperture  22  at a mounting interface  72  such that stone  50  is “locked” or fixed in place relative to frame  20 . The four flats advantageously distribute the rotational forces (loadings) on to several points, thus helping to avoid stone failure. 
     When frame  20  is subjected to a rotational force (such as by a crank, wheel, rod, shaft, arbors running through the aperture of the stone, etc.) stone  50  likewise rotates, but is substantially inhibited from independently rotating relative to frame  20  due to the geometric shapes of stone  50  and frame  20 . Because the perimeter of stone  50  is not exactly circular shaped, stone  50  does not generally slip or slide within aperture  22  when frame  20  is rotated. 
     In one embodiment, two substantially identical mounting systems may be placed in a facing relationship (not shown) in a disc or attrition mill (e.g., grinding machine) such that two or more stone faces can be placed in contact with each other. In another embodiment, one mounting system paces and rotates against another object, which may be fixed and/or different from the mounting system. To keep the stones from turning (i.e., not lock together due to the contact forces between them) each stone should be held in position relative to the frame of that stone. A material (such as rubber, biological products, agricultural products, elastomers, plastics, etc.) may be provided between two grinding surfaces  52  of two stones in a facing relationship in the grinding machine. The size of the material may be reduced by grinding it between the two grinding surfaces. The material may be ground pure or mixed with other materials such as by making a slurry and mixing the material with a liquid. Further, this invention can include the mounting of a single abrasive wheel, using the mounting method of the present invention, for the purpose of placing the single abrasive wheel in a facing relationship in a disc or attrition mill. Thereby the abrasive wheel is faced with any other type of grinding surface. The abrasive wheel face and the face of the other surface are thus capable of grinding any material between themselves. 
     Referring to FIG. 2, system  10  is shown according to an alternative embodiment of the present invention. Aperture  22  of frame  20  is generally hexagonal shaped and the perimeter of stone  50  is correspondingly hexagonal shaped. Stone  50  fits within aperture  22  of frame  20  such that stone  50  is rotated when frame  20  is rotated. 
     Referring to FIG. 3, system  10  is shown according to an alternative embodiment of the present invention. A protruding portion shown as a boss  28  extends from frame  20 . Boss  28  is generally hexagonal shaped. An aperture  58  of stone  50  is correspondingly hexagonal shaped. Boss  28  fits within aperture  58  of stone  50  such that stone  50  is rotated when frame  20  is rotated. 
     Referring to FIG. 4, system  10  is shown according to an alternative embodiment of the present invention. Aperture  22  of stone  20  is generally circular shaped and the perimeter of stone  50  is correspondingly circular shaped. Frame  20  provides a locking system  70  including a protrusion shown as an outwardly extending finger  30  of frame  20 , and a recess shown as an inwardly extending finger  62  of stone  50 . Stone  50  fits within aperture  22  of frame  20  and finger  30  interconnects with finger  62  such that stone  50  is rotated when frame  20  is rotated. According to alternative embodiments, the locking system may include a keyway as used in a locking a pulley on a shaft. 
     Referring to FIG. 5, system  10  is shown according to an alternative embodiment of the present invention. Frame  20  includes a protruding portion shown as a boss  32 , similar to boss  28 . Boss  32  is generally circular shaped and includes a recess shown as an inwardly extending finger  62 . An aperture  58  of stone  50  is correspondingly generally circular shaped, and stone  50  includes a protrusion shown as an outwardly extending finger  30 . Boss  60  fits within aperture  58  of stone  50  to interconnect fingers  30  and  62  such that stone  50  is rotated when frame  20  is rotated. 
     Referring to FIG. 6, system  10  is shown according to an alternative embodiment of the present invention. Aperture  22  of frame  20  is generally circular shaped and includes an oblique portion  26 . The perimeter of stone  50  is correspondingly circular shaped and includes a corresponding oblique portion  56 . The perimeter of stone  50  fits within aperture  22  and is aligned with frame  20  such that oblique portion  56  is aligned with oblique portion  26  such that stone  50  is rotated when frame  20  is rotated. 
     Referring to FIG. 7, system  10  is shown according to an alternative embodiment of the present invention. Aperture  22  of frame  20  is generally oval shaped and the perimeter of stone  50  is correspondingly oval shaped. Grinding surface  52  includes a protruding portion shown as a boss  60  extending from stone  50 . Boss  60  provides a supplemental grinding surface  74  for reducing the size of grinding materials (not shown). Stone  50  fits within aperture  22  of frame  20  such that stone  50  is rotated when frame  20  is rotated. 
     Referring to FIG. 8, system  10  is shown according to an alternative embodiment of the present invention. Frame  20  includes a recessed portion shown as a lock  40  having a generally triangular shape. Backing surface  54  of stone  50  includes a protrusion shown as a key  66  having a corresponding triangular shape. Key  66  fits within lock  40  of plate  20  such that stone  50  is rotated when frame  20  is rotated. 
     Referring to FIG. 9, system  10  is shown according to an alternative embodiment of the present invention. Aperture  22  of stone  20  is generally star shaped and the perimeter of stone  50  is correspondingly star shaped. Stone  50  fits within aperture  22  of frame  20  such that stone  50  is rotated when frame  20  is rotated. 
     Referring to FIG. 10, system  10  is shown according to an alternative embodiment of the present invention. Aperture  22  of frame  20  is generally oval shaped and includes an aperture  22 . The shape of the perimeter of stone  50  corresponds to the shape of aperture  22  in that it is generally oval. Stone  50  may be inserted within aperture  22  of frame  20  such that stone  50  is rotated when frame  20  is rotated. This embodiment applies rotational forces (loadings) on to two points, namely at the two narrower, elongated ends of the oval. 
     It is important to note that the construction and arrangement of the elements of the stone mounting system in the exemplary embodiments is illustrative only. Many variations are possible. According to alternative embodiments, the stone may be a unitary, contiguous piece or may be segmented into several pieces whereby each segment may be coupled with the frame to assemble the overall stone shape. The shape and configuration of the stone and the frame can be varied drastically. Examples of the shapes of the stones and frames are found but are not limited to those shown in the FIGURES, other shapes may include a square shaped stone coupled to an oval shaped frame. Complex stone shapes are envisioned such as star shapes, which engage a similar or correspondingly shaped frame. The mounting interface between the stone and the frame may be at the outer perimeter of the stone and/or frame, the inside perimeter of the stone and/or frame (e.g., the inside aperture or “donut”), at the perimeter of a boss or protrusion of the stone and/or frame, or a combination thereof. The stones can have various shaped grinding surfaces (e.g., beached or sloped, grooved, etc.) and various contours for improved commutation of materials. 
     According to alternative embodiments related to the locking system, keyway notches may be formed in the stone to accept notches associated with the frame. Also, the stone could have outwardly extending keys, which engage keyway notches in the frame. According to alternative embodiments related to the mounting interface between the stone and the frame, the stone and the frame may be coupled by fasteners such as bolts, adhesives (e.g., epoxies, glues, etc.), liquid metal (such as molten lead, sulfur, etc.), and the like. The stone may be pre-stressed before the grinder is operated (i.e., with locking taper mounting rings). According to other alternative embodiments, the stone may be substantially free of pre-stress (which, without intending to be limited by theory, is believed may reduce wear and increase longevity of the stone). 
     According to other alternative embodiments, the stone mounting system may be rotated or provided with translational motion at any speed from extremely high (e.g., about 3600 rpm) to extremely low (less than about 1 rpm). A preferable speed is between about 1800 rpm and about 3600 rpm. 
     Although only a few exemplary embodiments of the present invention have been described in detail in this disclosure, those skilled in the art who review this disclosure will readily appreciate that many modifications are possible in the exemplary embodiments (such as variations in sizes, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, or use of materials) without materially departing from the novel teachings and advantages of the invention. Accordingly, all such modifications are intended to be included within the scope of the invention as defined in the appended claims. Other substitutions, modifications, changes and/or omissions may be made in the design, operating conditions and/or arrangement of the preferred embodiments without departing from the spirit of the invention as expressed in the appended claims. The order or sequence of steps, for example, of providing the stone or the frame may be varied or re-sequenced according to alternative embodiments of the invention. 
     In the claims, any means-plus-function clause is intended to cover the structures described herein as performing the recited function and not only structural equivalents but also equivalent structures.