Plastic and nonmetallic article shaping or treating: processes – Mechanical shaping or molding to form or reform shaped article – Shaping against forming surface
Reexamination Certificate
2000-01-31
2003-03-04
Nelson, Jr., Milton (Department: 3636)
Plastic and nonmetallic article shaping or treating: processes
Mechanical shaping or molding to form or reform shaped article
Shaping against forming surface
C029S091100, C297SDIG001, C297SDIG002
Reexamination Certificate
active
06528002
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is generally directed to seating products, and is more particularly directed to a seating cushion comprised of a preformed polymeric three-dimensional enclosure configured to receive a resilient inner pad so as to cover the top, sides and at least a portion of the bottom of the pad. The seating cushion is particularly well suited for industrial and vehicular seating products.
2. Description of Related Art
Seating products such as chairs, stools and benches are commonly subjected to heavy wear and often times nearly continuous use, particularly in industrial or vehicular settings. In these and other environments, users may spill food, beverages, chemicals or other damaging materials onto the seating product. In such environments, seating products made from conventional upholstery materials must be repaired or replaced frequently, which can be quite expensive. Thus, there is a need for durable seating products that can withstand heavy use and spilled materials. In addition, in many industries, such as the pharmaceutical and microelectronics industries, there is a need for seating products that are not only durable, but are comprised of relatively inert materials suitable for use in a clean room environment. Unfortunately, because of the need for durable and/or inert seating products, comfort is often a secondary consideration in designing and purchasing these seating products.
Attempts to construct durable seating products suitable for clean room and other industrial use include providing solid molded polyurethane seat bottoms and backs. The solid polyurethane is highly durable and resists wear and spillage. In addition, the solid polyurethane is relatively inert and does not release particles that can contaminate a clean room environment. Although such seats are suitable for use in vehicles and clean rooms, the polyurethane is hard and uncomfortable. This can be a particular problem insofar as persons who work in clean rooms and other industrial settings are often required to remain seated for prolonged periods of time. Thus, use of solid polyurethane seating products can lead to unhappy workers, poor job performance and expenses related to health problems (e.g., back problems).
Other attempts to construct durable seating products have focused on vehicular seating products, such as seats or benches used in buses. U.S. Pat. No. 5,609,395 to Burch discloses bus seat modules comprised of an elastomeric skin bonded to a polyurethane foam interior and a plywood base. The bus seat modules are formed by coating the interior surface of a mold with a spray elastomer, inserting the plywood base into the mold and injecting urethane foam therebetween. The foam bonds to the skin and the plywood to form a unitary piece. Although the elastomeric skin may be durable, the method for spraying the elastomer into the mold expels harmful chemicals into the air and is difficult to control, resulting in wasted elastomer, overspray that requires clean-up, and inconsistencies in the thickness of the sprayed skin. Further, it is extremely difficult to position the spray gun to coat sharp angles or overhanging portions of the mold, and joining separately formed pieces of skin is generally unsatisfactory because overspray at the parting line makes joinder of the pieces difficult. Thus, the shape of the skin that may be produced utilizing spray elastomer is somewhat limited to shapes without overlapping walls or sharp angles.
Therefore, it is an object of the present invention to provide a durable seat cushion that can be utilized in heavy use environments, where the cushion is subjected to almost continuous usage, such as in industrial settings or for commercial vehicles.
It is a further object of the present invention to provide a durable seat cushion that can be easily cleaned and can withstand chemical spills.
It is another object of the present invention to provide a such a seat cushion that is as durable as conventional industrial seats, but is much more comfortable.
It is yet another object of the present invention to provide such a seat cushion that is suitable for use in clean rooms.
It is another object of the present invention to provide such a seat cushion that can be constructed accurately with predetermined characteristics.
It is another object of the present invention to provide such a seat cushion that can be constructed economically without significant waste.
SUMMARY OF THE INVENTION
The present invention is directed to a durable and relatively inert seating cushion comprising a preformed outer enclosure configured to cover and receive a resilient inner pad. The preformed enclosure is preferably three-dimensional and may be used in place of conventional upholstery in most seating products. The enclosure comprises a unitary polymeric wall that terminates in a lower peripheral edge to define an opening through which the pad can be inserted. Preferably, the wall comprises a substantially horizontal top wall, a peripheral side wall and a substantially horizontal bottom lip adjacent the lower peripheral edge. The bottom lip will cover a portion of the bottom surface of the pad contained within the enclosure.
The wall of the enclosure is relatively thick, which adds durability and structure to the seating cushion. However, the enclosure wall is sufficiently thin and of a density that allows the user to feel the characteristics of the pad contained within the enclosure. In a preferred embodiment, the enclosure is comprised of a unitary wall of polyurethane having a thickness of at least 0.030 inch, and a density ranging between 0.5 and 1.2 grams/cubic centimeter.
The enclosure is preferably formed by casting or injection molding using a two-sided mold. The two-sided mold allows the wall of the enclosure to be formed in a predetermined thickness, which thickness may vary at predetermined locations along the enclosure wall. In addition, a two-sided mold allows the enclosure to be formed with an overlapping bottom lip at the lower portion of the wall. After molding, a pad with the desired characteristics is inserted into the enclosure through the opening to form a cushion for use as a seat bottom, seat back, arm rest or headrest of a seating product.
A seating cushion formed using the preformed enclosure of the present invention is both highly comfortable and highly durable. Because the enclosure is formed separately from the pad, the characteristics of the enclosure can be varied independently of the pad without compromising the comfort of the seating cushion. Further, because the pad is not bonded to the enclosure, if the pad becomes compressed or otherwise unsuitable for use, or if the enclosure is somehow damaged, the pad and/or enclosure can be replaced without need to purchase an entire new seat.
In a preferred embodiment, the enclosure is formed in a two-sided mold, which allows the enclosure to be constructed with a consistent, repeatable and predetermined pattern of wall thickness. The two-sided mold also allows various shapes of enclosures, including enclosures having an overlapping lip. Also, because the enclosure is preformed into the desired three-dimensional shape, there are few of the wrinkles that result from utilizing a flat sheet of upholstery material to cover a pad. Although a cushion for a seat bottom is generally described herein and depicted in the figures, it should be understood that the seating cushion of the present invention may also be used to form back cushions, arm cushions, headrests and the like.
REFERENCES:
patent: 2725923 (1955-12-01), Bachrach
patent: 2845997 (1958-08-01), Waite
patent: 3353867 (1967-11-01), Anderson
patent: 3408106 (1968-10-01), Bolling et al.
patent: 3431023 (1969-03-01), Anderson
patent: 3612607 (1971-10-01), Lohr
patent: 3616171 (1971-10-01), Hoskinson
patent: 3669496 (1972-06-01), Chisholm
patent: 3713697 (1973-01-01), Koepke
patent: 4385783 (1983-05-01), Stephens
patent: 4566735 (1986-01-01), Frobose
patent: 4647109 (1987-03-01), Christophersen et al.
patent: 4768
Barber Karen
Denny Lee
Dieckhaus Rob P.
Wensel John D.
Cramer Inc.
Jr. Milton Nelson
Stinson Morrison & Hecker LLP
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