Frame construction for box spring assemblies

Abstract

A generally rectangular frame for supporting the springs in a box spring assembly consisting of horizontal side and end rails, a plurality of transversely spaced cross rails supported on and extending between the side rails, and a center rail supported on and extending between the end rails and interlocked with the mid portions of the cross rails so as to support the cross rails intermediate their ends. The cross rails and the center rail are longitudinally arched to provide a mattress foundation which is convexly arched in two directions when viewed from above. Telescoping bracket supports are provided for mounting the ends of the center rail on the wood end rails so as to eliminate the necessity for slotting the end rails and uniquely shaped tabs are struck out of the cross rails to enable easy interlocking of the center rail with the cross rails during assembly of the frame. The cross rails are shaped so that they have narrow strips of metal at their ends to enable use of a conventional stapling tool for attaching the cross rail ends to the wood side rails.CROSS REFERENCE TO RELATED APPLICATIONSThe present application discloses a box spring frame of the same general type as the frames disclosed in copending applications Ser. No. 886,468 filed Dec. 19, 1969 (U.S. Pat. No. 3,680,157) and Ser. No. 56,933 filed July 21, 1970 (U.S. Pat. No. 3,665,529), owned by the assignee of this application.BACKGROUND OF THE INVENTIONBox spring assemblies conventionally consist of a rectangular wooden frame having side rails, end rails and slats secured to the side rails and springs mounted on and extending upwardly from the wood frame. The wood is non-uniform, has reliability deficiencies and is becoming increasingly expensive but the introduction of steel or other suitable metals into such a product has heretofore been impractical from the standpoints of weight and economy. The principal object of the present invention, therefore, is to incorporate metal cross rails and a center rail into a box spring frame so as to replace the conventional wood slats with structural members which improve the quality, reliability and uniformity of the frame and, in addition, provide the box spring assembly with a highly desirable convex surface curvature which is important in all mattress foundations.SUMMARY OF THE INVENTIONThe box spring frame construction of this invention comprises substantially horizontal side and end rails formed of wood, a plurality of channel shape metal cross rails which are supported on and extend between the side rails, and a center rail which is supported at its ends on the end rails and is interlocked intermediate its ends with central portions of the cross rails so as to provide support for the cross rails intermediate their ends. The cross rails are prestressed so that they are longitudinally arched and pairs of downwardly extending tabs are struck out of the center portions of the cross rails. The center rail is similarly prestressed so that it is longitudinally arched and the center rail is assembled in a supporting relation with the cross rails by interlocking the center rail with the tabs on the undersides of the cross rails. The tabs that are struck out of the cross rails have downwardly inclined tail portions bent from the cross rails and free head portions which are of a progressively decreasing width in a direction extending away from the tail portions so that the head portions present minimum interference with the center rail during assembly. Telescoping brackets are arranged in a supporting relation with the ends of the center rail and are secured to the end rails to enable mounting of the center rail on the end rails without slotting the end rails. To further facilitate mounting of the cross rails on the side rails, the cross rails are provided with narrow strips of material at their ends to enable stapling of the cross rails to the side rails with a conventional stapling tool.The longitudinally arched shapes of the cross rails and the center rail provides a base for a spring assembly of uniform thickness which has a top deck that is convexly curved in two directions when viewed from above. As a result, the deck provides a mattress foundation which imparts this identical convexly arched configuration to the top surface of a mattress supported on the spring deck, a characteristic which is acknowledged to be highly desirable in quality bedding. Past box spring assemblies have required layers of cotton to achieve this desirable arched configuration. In addition, the frame of this invention has improved strength characteristics by virtue of the cooperative action of the cross rails and the center rail so that potential sag of the frame during use is substantially eliminated.

Description

Claims

1. A box spring assembly comprising a frame having substantially horizontal side and end rails and a plurality of transversely spaced cross rails supported on and extending between said side rails, each of said cross rails being pre-stressed so that it is longitudinally arched and being secured at the ends thereof to said side rails, the longitudinal arch in a cross rail providing for a location of the center portion thereof above the ends thereof, and a center rail extending transversely of said cross rails and secured at the ends thereof to said end rails, said center rail being connected intermediate the ends thereof to said cross rails and being pre-stressed so that it is longitudinally arched and has the center portions thereof disposed above the ends thereof, a plurality of springs forming a spring assembly of substantially uniform height and having a top deck, and means on said cross rails providing for the support of at least some of said springs thereon in predetermined fixed positions so that the top deck is convexly arched in two directions when viewed from above as a result of said arching of said cross rails and said center rail, said cross rails being generally U-shaped in transverse section and each having a base section and upright leg sections, said base sections being formed with downwardly extending tabs arranged in pairs and aligned with said center rail, and said center rail being interlocked with and arranged between the tabs in each pair.

2. A generally rectangular frame for a box spring assembly, said frame comprising side and end rails and a plurality of transversely spaced cross rails supported on and extending between said side rails, each of said cross rails being of channel shape in cross section and having a generally horizontal base section and upright leg sections, a center rail extending transversely of said cross rails and secured at the ends thereof to said end rails, said center rail being of generally V-shape in cross section and having generally horizontal flanges at the upper ends thereof extending outwardly in opposite directions, tabs struck out of at least some of said cross rail base sections, said tabs being arranged in pairs inclined downwardly toward each other and spaced apart longitudinally of said cross rails, each of said tabs having a downwardly bent tail portion integral with said base section and a head portion integral with said tail portion and inclined downwardly therefrom at a position below said base section, said head section terminating in an outwardly curved free edge, and said center rail being stressed so that said flanges thereof are urged outwardly into retained engagement between pairs of said tabs, said flanges being positioned between the head portions in a pair of tabs and the base section from which said tabs are struck.

3. A box spring frame according to claim 2 wherein each of said tab head portions has the free edge thereof curved so that said head portion is of a progressively decreasing width in a direction extending away from the tail portion integral with said head portion.