Solid material comminution or disintegration – Processes – Miscellaneous
Reexamination Certificate
2001-03-19
2004-04-13
Rosenbaum, Mark (Department: 3725)
Solid material comminution or disintegration
Processes
Miscellaneous
C241S101741, C241S034000
Reexamination Certificate
active
06719226
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a mobile paper shredding system. More particularly, this invention relates to methods and apparatus used in shredding large volumes of paper generated either by large businesses or multiple businesses located close together. It is primarily adapted for use in urban and suburban areas, although benefits of the system can be utilized at any location where there is a need for mobile paper shredding services.
BACKGROUND OF THE INVENTION
Truck-mounted paper shredding equipment is in common use today, primarily in urban environments. Typically, the shredding equipment is mounted on the bed of a truck which moves among office buildings to collect discarded office paper. This waste paper is fed into an opening or hopper of the shredding system, where it passes through a shredding apparatus, such as a hammer mill. Paper shredded by the hammer mill is then fed into a container typically located at the rear of the truck where it is stored until the container may be emptied. In this manner, discarded paper can be effectively compressed into a smaller volume of space for more efficient transportation to a municipal landfill or recycling center.
Problematic in the design of mobile paper shredders for use in an urban or suburban environment is the size and configuration of the equipment. Obviously, it is desirable for a shredding system to have a large storage capacity to reduce trips to the landfill or recycling center. It is also desirable to have a powerful shredding system to process waste paper as quickly as possible. However, these needs are often in conflict. With mobile shredding systems, large storage capacity reduces the space available for powerful shredding equipment and powerful shredding equipment typically reduces the available storage space for shredded paper. For example, in known mobile shredding systems, the paper feed and shredding equipment is mounted along the longitudinal axis of the truck bed, typically to allow for simple and direct power transfer from the drive train of the truck. Unfortunately, for a given size truck bed, the length of the shredding equipment directly affects the amount of available storage capacity for shredded paper. Increasing the length of the shredding equipment, to increase throughput of paper, directly decreases the amount of available storage.
Yet another problem with known mobile paper shredders is a lack of mobility in confined spaces. Indeed, in many large cities, buildings are separated by narrow alleys and loading docks, or other commercial receiving areas are located either in these alleys or, perhaps, underground garages. In either case, large trucks cannot easily maneuver into these confined spaces. As a result, the demand is great for smaller, more efficient configurations without sacrificing storage capacity. Besides the configuration and layout of the equipment, a further limiting factor on the ability of a mobile shredding system to operate in confined spaces is the lift system. In some known mobile shredding systems, the lift systems move waste paper containers through a fixed radius path away from the body of the truck until the waste paper container is positioned over an opening or hopper for the shredding system. Such lift systems require substantial lateral space around the perimeter of the truck body to allow the lift system to operate. A further problem is created when a loading dock is used. In such a case, the truck must be parked a precise distance from the loading dock in order for the lift system, in mid-stroke, to pick up a waste paper container from the loading dock.
Yet a further problem of paper shredding systems is generation of unwanted dust. While creating dust during paper shredding is inevitable, the creation of dust can be controlled. In known systems, dust is created due to shredder blades beating on paper, or paper beating on paper, rather than blades shredding paper. In such circumstances, paper fibers are exposed and excessive dust is created. These problems result from, among other things, an extended paper path between the infeed of paper and the shredding apparatus, overfeed of paper into the shredding apparatus, a poorly designed shredder or, perhaps, a combination of these factors.
Overfeed and jamming of shredding apparatus can be another major problem. This can cause significant delays and, in a worst case, can cause motor burn out, which can result in still further delays, substantial costs associated with replacement equipment, and even lost business and associated lost revenues.
SUMMARY OF THE INVENTION
The present invention relates to a mobile paper shredding system transversely mounted on a truck bed. Generally, the shredding system is designed and configured to be compact and lightweight such that a smaller truck may transport and operate the system. The system enclosure is aluminum reinforced plastic and all parts are steel or aluminum except for the shafts and components of the mill and augers and associated bearings and support structure.
The mobile paper shredding system comprises a lift system, a first feed system, a shredder, a second feed system, and a storage container with a sliding wall to remove shredded paper, all of which are installed within a truck bed-mounted enclosure. The lift system is used to elevate and dump the contents of a waste paper container into an opening in the top of the enclosure above the first feed system. The first feed system delivers the waste paper to the shredding equipment, a hammer mill. The hammer mill shreds the waste paper when the paper is struck by rotating blades on the hammer mill shaft against a separator plate. The shredded paper, when properly reduced in size, passes through a screen comprising multiple two-inch diameter openings. The second feed system or packer then packs the shredded paper passing through the screen into a waste container at the rear of the enclosure through an access door. Once the rearward portion of the enclosure is filled to capacity, the load is transported to place for disposal, typically a recycling center. The shredded paper is removed from the enclosure by advancing a rolling wall towards the rear of the enclosure which forces the packed, shredded paper from the enclosure.
The lift system of the preferred embodiment is constructed from aluminum to decrease the weight of the unit. It is designed with a limited profile, fitting within a small space of the overall enclosure to further enhance the paper shredder system's adaptability to be used in confined areas. The lift system is designed to operate in three stages: lowering to street level; elevation of the paper container substantially vertically along the side of the truck, rather than in a fixed radius path; and dumping of the container into the infeed opening of the shredding system. This further enhances use in confined areas. In addition, the configuration of the lift arms allows any of the three stages to be operated independently. In this way, a paper container may be engaged directly off an elevated loading dock, rather than from street level, by implementing only the second and third stages of the lift system. The result is a more efficient and compact lift system.
A feed control system is designed to prevent overloading the hammer mill. A key parameter is ensuring that the output of the hammer mill is greater than the input of the first feed system. Maintaining this relationship increases the capacity of the system by guaranteeing efficient operation of the hammer mill. In this regard, the feed control system employs a monitoring and feedback system to prevent overloading the hammer mill. More specifically, the rotational speed of the hammer mill is directly monitored. If the revolutions per minute of the hammer mill fall below a threshold amount, for example, 1800 rpms, a switch is triggered which stops the paper infeed—the first feed system. Stopping the first feed system allows the hammer mill to shred a sufficient amount of paper to decrease strain on the motor. Once the overfeed is eliminated
Rosenbaum Mark
Sheridan & Ross P.C.
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