Abstract:
A multi-disc assembly for releasable attachment to the shaft of a disc screen is provided. The multi-disc assembly includes a multi-disc hub of elastomeric material including multiple discs configured for use in the disc screen. The hub has a through bore configured for direct engagement over a shaft of the disc screen. A disc screen comprising the multi-disc assembly and method of using the multi-disc assembly are also provided.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a continuation of application Ser. No. 13/069,925 filed Mar. 23, 2011 incorporated herein in its entirety by this reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to machines used to separate particulate materials or mixed recyclable materials into difference fractions, and more particularly, to a disc assembly for a disc screen that allows its discs to be more easily removed and replaced. 
     RELATED ART 
     Disc screens have long been used to separate particulate materials such as wood chips into difference fractions, according to size. More recently disc screens have been used to separate or classify mixed recyclable materials into respective streams of similar materials such as broken glass, containers, mixed paper and newspaper. 
     A disc screen typically includes a frame in which a plurality of rotatable shafts are mounted in parallel relationship. A plurality of discs are mounted on each shaft and a chain drive rotates the shafts in the same direction. The discs on one shaft interleave with the discs on each adjacent shaft to form screen openings between the peripheral edges of the discs. The size of the openings determines the dimension (and thus the type) of material that will fall through the screen. Rotation of the discs, which have an irregular outer contour, agitates the mixed recyclable materials to enhance classification. The rotating discs also propel the larger articles which are too big to fall between the discs across the screen. The general flow direction extends from an input area where the stream of material pours onto the disc screen to an output where the larger articles pour off of the disc screen. The smaller articles fall between the discs onto another disc screen or a conveyor, or into a collection bin. 
     The discs of a disc screen normally have a central opening or bore that allows them to be slid over the end of a shaft which may have a round or square cross-section. See for example U.S. Pat. No. 4,836,388 of Bielagus granted Jun. 6, 1989. Over time, the discs wear out and must be replaced. It is not practical to re-surface or repair damaged or worn discs without removing them from the shafts of the disc screen. However, it is tedious to dismount the ends of the shafts of a disc screen from their respective bearings so that the old discs can be removed and replaced by sliding the discs off the ends of the shafts. Moreover, if only single disc is worn out or broken, it is usually necessary to remove several discs before the damaged or broken disc can be slid off the shaft. In order to alleviate these problems, a split disc was developed by CP Manufacturing, Inc. of National City, Calif. See U.S. Pat. No. 6,318,560 of Robert M. Davis granted Nov. 20, 2001. The split disc is comprised of two identical halves which are assembled around a shaft and tightly held together by a pair of bolt assemblies which clamp the disc to the shaft. Each disc half is made of an outer rubber portion which is stiffened with a rigid internal metal frame embedded inside the rubber portion. 
     While the split disc design is beneficial in removing particular discs without disturbing other discs on the shaft, typical disc screens may employ 600 or more discs. With so many discs, the process of replacing one disc at a time may still be too-time consuming. In order to alleviate these problems, multi-disc assemblies have been developed as demonstrated in U.S. Pat. No. 7,261,209 to Duncan, et. al. The multi-disc assemblies comprise multiple discs that can be replaced at the same time, reducing the amount of effort in servicing a disc screen. However, the multi-disc assembly of Duncan involves a complex mounting arrangement involving a securing hub and mounting plate between the multi-disc assembly and the shaft. Thus, it would be desirable to provide a multi-disc assembly that is even more convenient to remove and install. 
     SUMMARY 
     In accordance with an embodiment of the present invention, a multi-disc assembly for releasable attachment to the shaft of a disc screen is provided. The multi-disc assembly includes a multi-disc hub of elastomeric material including multiple discs configured for use in the disc screen. The hub has a through bore configured for direct engagement over a shaft of the disc screen. The hub has a longitudinal separation plane which splits the hub into two separate multi-disc hub halves. The longitudinal separation plane defines first and second radial end faces in each hub half which extend along opposite sides of the through bore and oppose corresponding first and second radial end faces in the other hub half. Each hub half has at least one first connecting portion extending up to the first radial end face and at least one second connecting portion extending up to the second radial end face. The multi-disc assembly also includes a first rigid insert between the opposing first radial end faces and a second rigid insert between the opposing second radial end faces. The multi-disc assembly also includes at least two fastener devices configured to releasably secure the hub halves together around the shaft. The fastener devices include a first fastener device configured to extend through the first connecting portions of the hub halves and the first rigid insert and a second fastener device configured to extend through the second connecting portions of the hub halves and the second rigid insert. 
     Other features and advantages of the present invention will become more readily apparent to those of ordinary skill in the art after reviewing the following detailed description and accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded perspective view of a multi-disc assembly and a shaft of a disc screen; 
         FIG. 2  is a perspective view of a multi-disc hub half and rigid inserts; 
         FIG. 3  is perspective view of a multi-disc assembly; 
         FIG. 4  is a top plan view of a multi-disc hub; 
         FIG. 5  is a side elevation view of one multi-disc hub half; 
         FIG. 6  is a cross sectional view of the hub half on the lines  6 - 6  of  FIG. 5 ; 
         FIG. 7A  is a bottom plan view of a multi-disc hub half; 
         FIG. 7B  is a cross-sectional view of the hub half on the lines  7 B- 7 B of  FIG. 7A ; 
         FIG. 7C  is a cross-sectional view of the hub half on the lines  7   c - 7   c  of  FIG. 7A ; and 
         FIG. 8  is a top plan view of a rigid insert. 
     
    
    
     DETAILED DESCRIPTION 
       FIGS. 1 to 8  illustrate one embodiment of a multi-disc assembly  10 . In  FIG. 1 , a multi-disc assembly  10  is positioned about a hollow rectangular shaft  24  with radial corners. While shown in an exploded view in  FIG. 1 , the multi-disc assembly  10  is configured for direct engagement with the shaft  24  when assembled as shown in  FIG. 3 . Only a portion of the shaft  24  is shown in  FIG. 1 . The shaft would typically be long enough to support more multi-disc assemblies. The ends of the shaft  24  are supported by bearing assemblies (not illustrated) of a disc screen (not illustrated) such as those disclosed in U.S. Pat. No. 6,250,478 of Robert M. Davis granted Jun. 26, 2001 and U.S. Pat. No. 6,648,145 of Robert M. Davis et al. granted Nov. 18, 2003, and co-pending U.S. patent application Ser. No. 10/044,222 of Robert M. Davis filed Nov. 21, 2005, the entire disclosures of which are incorporated herein by reference. 
     The multi-disc assembly  10  is basically two opposing multi-disc hub halves  12 , a pair of rigid inserts  32  located between the hub halves  12 , and fasteners  36  which secure the hub halves and inserts around the shaft  24 , as described in more detail below. The hub halves  12  are positioned on opposing sides of the shaft  24 . Each hub half  12  has a plurality of integrally formed discs  18  with spacers  20  positioned between adjacent pairs of the discs  18 . The discs  18  are specially configured for use in classifying mixed recyclable materials. In particular, the discs  18  are configured for engaging materials to be classified (not illustrated) and propelling the materials in a conveying direction when the multi-disc assembly  10  is rotated. For example, if the multi-disc assembly  10  is rotated clock-wise in  FIG. 1  the materials would be propelled to the right. A through bore  26  in multi-disc assembly  10  is configured for direct engagement with the shaft  24 . In one embodiment, the through bore  26  is rectangular with radial corners. The through bore  26  interfaces with the shaft  24  in order to maintain the multi-disc assembly  10  in a fixed relationship with respect to the shaft  24 . In alternative embodiments, multi-disc assemblies may be provided with through bores of different shapes, such as circular or other shapes for engaging around shafts of corresponding shape. 
     A longitudinal separation plane  16  (see  FIG. 3 ) divides the two hub halves  12 . The longitudinal separation plane defines radial end faces  34  of the hub halves  12 . The radial end faces  34  extend on opposites sides of the through bore  26  on each hub half  12 . The radial end faces  34  of one hub half  12  oppose the radial end faces  34  in the opposing hub half  12 . 
     Connecting portions  14  extend up to the radial end faces  34  of the hub halves  12  as best illustrated in  FIGS. 2 ,  3 , and  7 B. In one embodiment, the connecting portions  14  are formed in on or more of the spacers  20 . The connecting portions  14  include bores  28 . The bores  28  in the corresponding connecting portions  14  of opposing hub halves  12  are aligned. Fastener devices  36  releasably secure opposing hub halves  12  about the shaft  24 . The fastener devices  36  extend through the bores  28  in the connecting portions  14  of opposing hub halves  12 . In one embodiment, the radial end faces  34  each have an elongate recess  38 . 
     Rigid inserts  32  are shown in  FIGS. 2 and 8 . The rigid inserts  32  may be made of metal, such as cast Aluminum and have holes  30  configured for alignment with the bores  28  in the connecting portions  14 . Rigid inserts  32  include bores  30 . In one embodiment, the rigid inserts  32  are configured to interface with the radial end faces  34 . In another embodiment, the rigid inserts  32  are configured to be received in elongate recesses  38  in the opposing radial end faces  34 . In the illustrated embodiment, the rigid inserts  32  are embedded in the body of the hub half  12  proximate the radial end faces  34 , as illustrated in  FIGS. 6 and 7A . The holes  30  align with the bores  28  in the connecting pieces  14  of the hub halves  12 . Each securing device  36  extends through the bores  28  in the connecting portions  14  and through the aligned hole  30  of the respective rigid insert  32 . In one embodiment, the securing device is a stainless steel bolt or threaded fastener that extends through the bore in the bores  28  in the connection portions  14  and the bore  30  through the rigid insert  32 . The male end is screwed into a female threaded nut. Other forms of securing means can be utilized, such as ancillary collars, clamps, brackets and/or sleeves for indirectly attaching the hub halves  12  in releasable fashion. 
     Referring to  FIG. 3 , a multi-disc assembly  18  is shown. Longitudinal separation plane  16  separates the two hub halves  12 . Each of the discs  18  has a major and a minor axis. The major axes of adjacent discs  18  may be out of alignment by a predetermined angle. In one embodiment, the major axes of each pair of adjacent discs  18  on the multi-disc assembly  18  is out of alignment by approximately 90 degrees. Other angles may also be used. While five discs  18  are illustrated, often multi-disc hubs may have a greater or smaller number of integral discs. In one embodiment, the spacers  20  are circular and have a diameter approximately equal to the size of the minor axis of the discs  18 . The connecting portions  14  are formed as flanges in portions of the spacers  20 . 
     In one embodiment, the hub half  12  is molded from an elastomeric material. Each disc  18  has an inner surface  40  that defines a portion of an interior cavity  44  as shown in  FIGS. 1 ,  3 , and  5 . The interior cavity  44  may be larger in a radial dimension than the through bore  26  in some areas, with inner surfaces  40  of at least some discs fitting closely about the shaft. Accordingly, the hub half  12  may contact the shaft  24  along less than entire length of the hub half  12 . In one example, the hub half  12  contacts the shaft  24  in two areas near the end portions  13  of the hub half  12 . Advantageously, this allows a sturdy connection between the hub half  12  and the shaft  24  while also allowing the hub half  12  to be formed of a smaller amount of material. In one embodiment, the hub half  12  is formed of an elastomeric material, i.e. a rubber-like synthetic polymer such as silicone rubber or polyurethane 
       FIG. 7A  is a bottom view of one hub half  12  which is broken away to reveal the embedded rigid insert  32  adjacent one radial end face  34 . In this embodiment, a rigid insert  32  is positioned within the hub half  12  parallel with the radial end face  34 . The holes  30  through the rigid insert  32  are aligned with the bores  28  through the two connecting portions  14 . As shown in  FIG. 7   b  the spacer  20  has an inner surface  46  that defines part of interior cavity  44 . Thus, hub half  12  has rigid inserts embedded adjacent each radial end face  34 . The opposing hub half may have similarly located rigid inserts or inserts may be located in only one hub half. 
     The hub halves  12  may be integrally molded as one unitary piece of elastomeric material in a mold (not illustrated), then separated into two halves along the separation plane  18 . In one embodiment, the molding occurs after the rigid inserts  32  have been positioned within the mold. The use of synthetic rubber, polyurethane or other similar durable elastomeric materials ensures that the discs  18  will have high friction impacting surfaces to maximize their propelling. The use of elastomeric material also minimizes the likelihood that glass containers will be broken. 
     The multi-disc assembly  10  is easier to dismount and mount than prior multi-disc assemblies because it attaches directly to the shaft  24  without any intervening securing hubs or mounting plates. 
     While I have described alternate embodiments of my invention, variations and modifications will occur to those skilled in the art. For example, the through bore need not be rectangular, but could be circular, triangular, oval, etc. to accommodate shafts having matching outer cross-sections. The multi-disc assembly could also be made entirely of metal for the purpose of crushing glass. Therefore, the protection afforded my invention should only be limited in accordance with the scope of the following claims.