Beds – Mattress – Having innerspring-type core
Reexamination Certificate
1999-12-15
2001-07-17
Trettel, Michael F. (Department: 3628)
Beds
Mattress
Having innerspring-type core
C005S268000, C267S091000, C029S091100
Reexamination Certificate
active
06260223
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to spring units for use in mattresses, spring upholstered furniture and the like and, more particularly, to an improved pocketed coil spring unit and associated method of manufacturing such a spring unit.
A well known type of spring assembly includes a number of discrete coil springs, each of which is enclosed in a fabric pocket in a length of folded fabric material. Longitudinal axes of the spring coils are generally parallel with one another so that the top and bottom end turns of the coil springs define top and bottom faces of the spring unit. A spring assembly can be fabricated from such a spring unit by forming rows of the pocketed coil springs and binding or adhering the individual rows together to form a mattress or spring assembly.
This type of spring assembly is commonly referred to as a pocketed spring unit due to the fact that each spring is contained within an individual pocket of fabric material. The construction of strings of pocketed coil springs in each pocket is well known in the art and, for example, disclosed in U.S. Pat. No. 4,439,977 which is hereby incorporated by reference in its entirety. The system disclosed in that patent includes a spring coiler which forms a coil spring which is subsequently compressed and inserted between the plies of folded pocketing fabric material. Other systems for manufacturing pocketed coil spring assemblies are disclosed in PCT Patent Application No. WO94/18116 and U.S. patent application Ser. No. 08/927,051 filed Sep. 10, 1997, each of which are expressly incorporated herein by reference.
Pocketed spring units are generally recognized to have a unique and particular luxurious feel to them and mattresses manufactured of such pocketed spring units provide a feeling of softness without lacking spring resilience or support. Mattresses and similar articles constructed of pocketed spring units are often considered a high-end type of product because of the added benefits and features of the pocketed coil springs. Mattresses and the like of this type can be more costly to manufacture and assemble as a result of the considerable amount of time and labor which is involved in their manufacture, together with the fact that the method of fabrication and assembly of such pocketed spring units can be complicated, particularly in an automated process.
While known systems provide an automated method for producing and assembling pocketed spring units, the increased cost of materials and associated components for mattresses and other items incorporating such spring units can be a detriment to the commercial success of these products, even though they do provide enhanced softness and support as previously described.
Therefore, there is a need for an improved pocketed spring unit and associated method of manufacture which offers all the advantages of known pocketed spring units without the associated higher manufacturing costs and related disadvantages of known pocketed spring units.
SUMMARY OF THE INVENTION
These and other objectives of the invention have been obtained by an improved pocketed coil spring unit and associated method of manufacture for mattresses, spring upholstered furniture and the like according to this invention.
In one embodiment of this invention, a number of spring sets, each of which includes a first coil spring and a second coil spring which are joined together by a connecting wire at corresponding end turns of the first and second coil springs, are utilized. Each spring set is formed from an integral piece of spring wire. The spring sets are each encased in fabric pockets such that a grouping of adjacent fabric pockets includes first, second and third pockets which are serially connected with the third fabric pocket being between the first and second fabric pockets. The first coil spring of each spring set is inserted into the first fabric pocket and, likewise, the second coil spring of each spring set is inserted into the second fabric pocket. The connecting wire joining the coil springs spans the third fabric pocket which, in one embodiment of this invention, is empty with the exception of the connecting wire. The spring unit includes a number of such pocketed spring sets with the connecting wire being alternately positioned near a top or a bottom of the spring unit.
The pocketed coil spring unit of this invention can be used to form a mattress or other spring assembly of pocketed springs wherein every third pocket is left empty without a spring therein. As such, one goal of the invention is achieved by reducing the total amount of wire needed to form a pocketed spring coil mattress. The absence of one-third of the springs that are normally in a mattress drastically reduces manufacturing costs. Moreover, the ability to skip every third pocket does not diminish performance of a pocketed coil mattress because of the connecting wire joining the spring coils of each spring set. The connecting wire bridges over or spans the empty pocket so that when someone sits or lays on the mattress, the connecting wire spreads the load across the empty pocket and distributes the load to the adjacent springs. Advantageously, the connecting wire is located on the top and bottom surfaces of the spring unit so that the mattress or the like may be conveniently flipped top to bottom without altering its performance characteristics.
Another aspect of this invention is a method for manufacturing the pocketed coil spring unit such that each spring set is manufactured from a wire coiler which initially forms the first coil spring from one end turn to an opposite end turn of that coil spring. A connecting wire is then formed to project from the end turn of the first spring coil. Subsequently, the opposite end turn and the remainder of the second spring coil is formed. As such, a connecting wire joins opposite end turns of the first and second coil springs. The coil springs are then pivoted or manipulated relative to one another so that one coil spring is inverted, pivoted or manipulated relative to the other so that the connecting wire joins corresponding end turns of the two joined coil springs at either the top or bottom of the spring set depending upon its orientation. The spring set with the connecting wire joining corresponding end turns of the two coil springs is then inserted into the fabric pockets as previously described with the connecting wire spanning an empty pocket positioned between the two pocketed and joined coil springs. The pocketed spring sets are then arranged and assembled into the desired spring unit, mattress or the like.
As such, with this aspect of the invention, standard spring coiling machines can be used to produce the spring sets for use in spring units, mattresses or the like thereby avoiding the need for additional capital costs, machinery and complicated manufacturing processes and techniques.
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Mossbeck Niels S.
Wells Thomas J.
Leggett & Platt Incorporated
Trettel Michael F.
Wood Herron & Evans L.L.P.
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