Patent Application
20070138068
The present invention relates to machines used to separate particulate materials or mixed recyclable materials into difference fractions, and more particularly, to a disc construction for a disc screen that allows its discs to be more easily removed and replaced.
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 singe 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, California. 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 aforementioned patented two-piece disc construction has been commercially successful, it would be desirable to provide a disc construction that is even more convenient to remove and install.
In accordance with an embodiment of the present invention, a disc for releasable attachment to a shaft of a disc screen apparatus includes a generally ring-shaped hub. The hub has a bore and a split defining a pair of opposing ends. The hub also has a hinge intermediate the opposing ends that permits the opposing ends of the hub to be separated a predetermined distance sufficient to allow the shaft of the disc screen apparatus to pass between the opposing ends into the bore. A plurality of outer impacting elements are supported on the hub and are configured for engaging materials to be classified and propelling the materials in a conveying direction when the hub is rotated. A mechanism is provided to secure the hub to the shaft so that the shaft extends through the bore.
Referring to
Referring to
The hub segment 16c has sufficient flexibility to allow the opposing ends 16a and 16b to be manually separated for mounting the hinged disc 14 on the shaft 12. A pair of identical rigid inserts 24 and 26 are embedded in the hub 16 on opposite sides of the hinge segment 16c. The inserts 24 and 26 are preferably made of metal, such as cast Aluminum. The lightweight metal inserts 24 and 26 provide additional strength and rigidity to accommodate means for securing the hub 16 to the shaft 12 so that the shaft 12 extends through the bore 18. The opposing ends 16a and 16b of the hub 16 and the inserts 24 and 26 have complementary mating shapes to aid in aligning these opposing ends when the hub 16 is secured to the shaft 12. More particularly, the mating shapes have a saw-tooth configuration such as 26a as best seen in
In the form illustrated, the means for securing the hub 16 to the shaft 12 comprises a fastener in the form of a stainless steel bolt 28 (
The impacting elements 22 (
The hinged disc 14 is preferably integrally molded as one unitary piece of elastomeric material in a mold (not illustrated) after the inserts cast Aluminum 24 and 26 have been positioned within the mold. The use of synthetic rubber, polyurethane or other similar durable elastomeric materials ensures that the impacting elements 22 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 hinged disc 14 is easier to dismount and mount than prior split discs because it is lighter, and only requires a single bolt to be removed and replaced. Also, the repairman does not need to hold up two separate disc pieces around the shaft, and try to insert bolts at the same time. A disc screen may incorporate several hundred discs, and the savings in terms of materials (expensive stainless steel bolts) and installation time can be significant. Moreover, the lighter weight of the hinged disc 14 than conventional split disks lessens the likelihood of damaged bearings, bent shafts and broken shafts.
Instead of using a segment of an elastomeric hub as the hinge, in an alternate embodiment the hinge may comprise a mechanical hinge assembly portion of the hub. Referring to
While I have described alternate embodiments of my invention, variations and modifications will occur to those skilled in the art. For example, both the shape and number of the plurality of outer impacting elements can widely varied to meet the needs of the materials being classified. For example, the disc could have a star configuration with rounded or sharp tips, or it could have a square configuration with rounded corners, or it could have an undulating outer contour as disclosed in U.S. Pat. No. 4,795,036 of Williams, or it could have a triangular contour with curved edges joining angled apices as disclosed in U.S. Pat. No. 5,799,801 of Clark et al. The bore 18 need not be circular, but could be rectangular, triangular, oval, etc. to accommodate shafts having matching outer cross-sections. The hinged disc 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.
