Supports: racks – Of wire
Reexamination Certificate
1999-07-01
2001-09-11
Stodola, Daniel P. (Department: 3634)
Supports: racks
Of wire
C211S191000
Reexamination Certificate
active
06286693
ABSTRACT:
CROSS REFERENCES TO RELATED APPLICATION
STATEMENT AS TO RIGHTS TO INVENTION MADE UNDER FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT
BACKGROUND OF THE INVENTION
The present invention relates to structures for supporting palletys in general, and to rack systems which receive plastic pallets in particular.
The second half of the 20th century has seen the widespread use of pallets for the effective and economical storage and transport of goods and commodities of all kinds. Palletized material handling means that goods are handled not as distinct custom loads, but as repeatable elements in a streamlined flow. The tremendous economic advantage to handling material on pallets, as opposed to specialized containers, has supported an enormous investment throughout the world in standardized material handling equipment including hand trucks, forklift vehicles, and rack storage systems. For decades, the wooden pallet assembled from hardwood planks and steel nails has been the world standard. Much of the support infrastructure has been configured to accommodate the attributes of a hardwood pallet. Pallet handling equipment and pallet supports are tailored to the rigidity, maximum deflection, and strength of a wooden pallet.
Nevertheless, despite the widespread acceptance of wooden pallets there is also a growing acknowledgment of the inadequacies of wood in today's demanding pallet environment. Pallets made of plastic are splinter and rust free, resistant to rot, uniform, nestable, easily adapted to custom cargoes, and have a greatly extended useful life when compared to wooden pallets. Even with these many benefits, there are certain attributes of plastic which cannot be overlooked. First, if the plastic is to be resilient enough to withstand the rough treatment of commercial transportation, it will be of lower strength and rigidity than wood. Second, plastic by weight is usually more costly than wood.
By the use of reinforcements and thoughtful engineering, a plastic pallet can be designed to equal the performance of a wooden pallet in terms of maximum deflection, load carrying capability, and length of unsupported span. However, a pallet requiring significant additional material comes at a measurable increase in cost. When the vast scale of local, national, and international material flows is taken into account, with their large inventories of pallets, the cost of conversion can be daunting.
A pallet is subjected to a variety of different loading conditions at different stages in the transportation system. At rest, all the pallet legs are disposed on a planar floor or an underlying load. In transport, the pallet deck supports the loads on the tines of a lift truck. A particularly demanding loading condition is rack support in which the outer legs of the pallet carry the full load. Wooden timbers perform very well when crossing an open span. To match this performance a plastic pallet will typically require reinforcement with metal or other material, with a significant increase in pallet cost.
Numerous warehouses throughout the country are outfitted with pallet supporting rack systems having thousands of positions to receive loaded pallets. These rack systems are generally configured to receive wooden pallets, and represent an enormous investment in infrastructure. These rack systems typically have front and rear beams which support the pallet in a clear span. Metal mesh decks are available which extend between the rack front and rear beams and which support smaller or less stiff loads. However, these mesh decks are usually uniform arrays of rods or wires and not particularly adapted to minimizing deflection. Moreover, the plastic pallet can be marred or deformed if too great a load is carried on a single wire. Rather than utilize costly reinforced plastic pallets which can be employed with historic rack systems, low cost pallets could be used if a rack support system were available which did not impose such challenging demands on the pallet. An additional benefit is the purchaser of the rack deck maintains control over the investment, and it will far outlast the life of any particular pallet. If a deck could be supplied which permitted the use of lower cost pallets, and which could be acquired for about the cost differential between a plastic pallet of rigidity similar to wood, and one which is not, the conversion to widespread use of the advantageous plastic pallets would be greatly facilitated.
What is needed is an economical deck which can be retrofitted to conventional rack systems to support conventional plastic pallets to provide a cost-effective plastic pallet storage system.
SUMMARY OF THE INVENTION
The plastic pallet support deck of this invention is a metal structure received on the front and rear beams of conventional rack systems. The deck is specially configured to receive a conventional four-way entry nine leg plastic pallet, and will also accept a conventional wood pallet. Weight and cost efficiency in the deck is achieved by concentrating the deck mass in those segments of the deck which make contact with the legs of the plastic pallet, and more particularly by recognizing that the center row of pallet legs carries a greater fraction of the pallet load then each of the outside rows of pallet legs. The deck may be formed of steel wire, with closely spaced parallel front to back wire sections defining pallet leg row segments specifically to support the three rows of legs in a plastic pallet. The close spacing of the wires distributes the load of a pallet leg over multiple wires, reducing the point forces tending to deform the leg plastic. Front to back wires with an upwardly opening v-section are connected by struts to the wires within each support segment. Thus a single truss is formed as a part of each side support segment, and two trusses are formed as a part of the center support segment. Hooks extend downwardly and rearwardly from the front of the deck which are engagable beneath or within the front beam of a rack. A single wire is fixed to the front of the deck to project upwardly from the three support segments to serve as a quake stop or restraint against supported pallets moving in response to external forces. A front lip restrains rearward movement of the deck and downwardly bent wires at the rear of the deck prevent frontward movement. Sections of the wires forming the support surface of the deck are bent upwardly and connected to define side stops and a rear stop which restrain the pallet legs on the deck. The deck support segments may also be formed as stamped or roll-formed segments of steel sheet and still present some or all of the aforementioned features.
It is an object of the present invention to provide an economical deck for efficiently supporting the loads imposed by a supported plastic pallet.
It is also an object of the present invention to provide a deck specially configured to support a plastic pallet having four way entry.
It is another object of the present invention to provide a structure for retrofitting conventional rack assemblies intended for wooden pallets to accept plastic pallets.
It is also an object of the present invention to provide a pallet support rack with structure which restrains the escape of a supported pallet.
It is yet another object of the present invention to provide a pallet support deck for a rack system which is resistant to unintended removal from the supporting rack structure.
It is still another object of the present invention to provide a pallet support deck which retains plastic pallets thereon despite minor earth tremors, or unintentional contact with equipment.
It is a further object of the present invention to provide a pallet support deck which does not significantly deface or mar the supported plastic pallet.
It is an additional object of the present invention to provide a pallet support deck for a pallet rack which accommodates low cost plastic pallet, as well as wooden pallets of conventional design.
Further objects, features and advantages of the invention will be apparent from the following detailed de
Alltrista Corporation
Lathrop & Clark LLP
Stodola Daniel P.
Tran Khoa
LandOfFree
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