US 3559219 A
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0. P. MOLT BED FRAME WITH A BUILT-IN SPRING CORE Feb. 2, 1971 I 2 Sheets-Sheet 1 Filed Deg. 26, 1968 INVENTOR OttO Mo\t SPAYTOU R A varrow ATTORNEYS Feb. 2, 1971 o. P. MOLT 3,559,219
7 BED FRAME WITH 'A BUILT-IN SPRING CORE FiledDeq. 26. 1968 2 Sheets-Sheet 2 INVE'N'I'OR ean-Ow In; eax-rau ATTORNEYS 3,559,219 BED FRAME WITH A BUILT-IN SPRING CORE Otto P. Molt, Haubersbronn, Wurttemberg, Germany Filed Dec. 26, 1968, Ser. No. 787,028 Claims priority, application Germany, Dec. 28, I967,
Int. Cl. A47c 23/02, 23/04 U.S. Cl. 247 11 Claims ABSTRACT OF THE DISCLOSURE This invention relates to a bed frame with a built-in spring core. An object of this invention is to provide a bed frame with a built-in spring core which is easy to manufacture and almost noiseless in use.
According to the invention there is provided a bedframe having anchoring grooves therein and a built-in ited States Patent 0 spring core, said core comprising elastic springs with polygonal pitch-free end turns, tension members of elastic material connected to the corners of the elastic springs and anchoring elements at the ends of the tension members and inserted in said anchoring grooves.
In this way, it is possible to obtain, between the bed frame and the spring core, a strain-proof connection which follows all the movements of the spring core and produces hardly any noise during its sliding movements relative to the spring wire and the sides of the frame.
The underneath of the spring core is preferably braced more tightly than the top. As a result, the underneath of the spring core sags less underload than the top and to a large extent is self-supporting.
The tighter bracing of the underneath of the spring core is preferably obtained by arranging the anchoring grooves for the tension members in the underneath of the sides of the frame further to the outside. In this way, the same tension members may be used above and beneath.
The sides of the bed frame are preferably made from sheet metal in the form of rectangular hollow sections or profiles in whose upper and lower wall portions the longitudinally extending anchoring grooves are formed.
Near one corner, the rectangular metal section is preferably closed by an inwardly directed overlap which prevents the metal section from springing open. So far as production is concerned, this is cheaper and more reliable than welding.
The flexible tension members, which are preferably made of a plastics material, are with advantage joined together on the lines of a chain by distance stays which join their anchoring lugs together in one piece. In this way, it is possible to insert all the tension members of one whole side of the bed frame into the groove in a single operation and without any special measures to obtain the appropriate interval between the tension members.
An embodiment of the invention is diagrammatically illustrated by way of example in the accompanying drawings, wherein:
Patented Feb. 2., 1971 FIG. 1 diagrammatically illustrates part of a bed frame according to the invention.
FIG. '2 is a cross section through one side of the bed frame with an elastic spring attached to it.
FIG. 3 shows a chain of tension members.
FIG. 4 is a detail from FIG. 2.
Sides 1 of the rectangular bed frame are hollow sections rectangular in profile made from sheet metal, whose four wall portions have been numbered 2, 3, 4 and 5. Longitudinally extending grooves 6 and 7 which widen inwardly in dovetail-fashion are formed in the upper and lower wall portions 2 and 4 of the frame sides 1. The grooves may even be circular or angular in cross section. The metal profile or section is closed near one corner in the wall portion 3 which in front of the corner has an inwardly bent (at right-angles) marginal strip 8 overlapped by a bent marginal strip 9 on the lower wall por-, tino 4. The inwardly directed overlap 8, 9 prevents the hollow section from springing open.
The spring core 10 consists of waistlike elastic springs 11 whose pitch-free end turns 12 and 13 are square in outline and substantially in the middle of one frame side are so closed as to be strain-resistant. To this end, the free ends of the wire in the embodiment shown are bent into hooks 14 which engage in hooklike bends 15 formed at the junctions in the wound structure. From a centre portion 16, the wound structure is wound in opposite directions towards both ends of the spring. At the corners of the square end turns 12 and 13, the spring wire is bent in stages substantially corresponding to the thickness of the wire to enable the end turns of adjacent springs to interengage at the corners free from tension. Elastic springs of this kind are known from U.S. Pat. No. 3,161,408 and British Pat. No. 937,152. The elastic springs 11 are linked together at the corners of their end turns. In the embodiment shown, the springs are linked directly together in the rows which run parallel to the frame sides 1 shown in FIG. 1. In the rows extending transversely of the frame sides, the end turns of the springs are joined together by wire clips 17.
The spring core is joined to and braced with the fours1des of the frame by flexible tension members 20. At their ends, the tension members 20, preferably injectionmolded from plastics, have downwardly and inwardly bent hooks 21 through which they engage in those corners nearest the frame sides of the upper and lower end turns of the outer elastic springs of the spring core. At their other ends, the tension members 20 have bends 22 which widen into heads 23 adapted to fit into the grooves 6 and 7 in the frame sides 1. Through the heads 23, the tension members can be inserted into the grooves along the frame sides. Since the grooves widen inwardly in dovetailfashion, the tension members 20 are anchored in the sides of the frame through their heads 23 and are able to transmit appreciable tension. The arrangement is such that the tension members 20 firmly brace the spring core with the sides of the frame (in the planes of the end turns). Since the tension members 20 are flexible they are able to follow any movements of the end turns of the elastic springs produced by loads exerted upon the spring core, without being permanently deformed.
The underneath of the spring core with the end turns 13 is braced more tightly between the sides of the frame than the upper side with the end turns 12. To this end, the anchoring groove 7 of the lower wall portion 4 of the frame sides is arranged further to the outside than the anchoring groove 6 of the upper wall portion 2, as shown in FIG. 2. In this way, the undernearth of the sprung core may be more tightly braced with the same tension members 20.
FIG. 3 shows how a plurality of tension members 20 can be joined together by distance stays 25 which interconnect the anchoring heads 23 of adjacent tension members, in such a Way as to form a chain which can be inserted as a whole into the grooves 6 and 7 of the frame sides 1.
The tension members can be made very easily by injection-moulding providing the hook 21 is turned through 90 before production. In addition, the anchoring head 23 can be arranged in such a way that its inwardly directed triangular side extends at an angle of somewhat more than 90 to the centre portion of the tension element (substantially corresponding to the upper tension member 20 in FIG. 2). The tension member may then be injected in a simple two-part mould. By virtue of its elasticity, the tension member may be deformed as required during fitting.
FIG. 4 shows a detail from FIG. 2, namely the lefthand side of the lower tension member 20, which underneath has a hooklike lug 26 which is open towards the inside of the sprung core. At the lower end of the frame, a tension element 28, for example in the form of a wire or band, is sewn into an upholstery fabric 27 which runs upwards on the outside of the frame and covers the similarly upholstered sprung core over its upper surface. This wire is readily engaged in the hooklike lugs 26.
1. A bed frame having anchoring grooves therein and a built-in spring core, said core comprising elastic springs with polygonal pitch-free end turns, tension members of elastic material connected to the corners of the elastic springs and anchoring elements at the ends of the tension members and inserted in said anchoring grooves.
2. A bed frame as in claim 1, in which said anchoring grooves being formed on the upper and lower sides of the frame and in which the tension members inserted in said lower grooves brace the underside of the spring core more tightly against the frame than the tension members inserted in said upper grooves.
3. A bed frame as in claim 2, in which the lower anchoring grooves for the tension members being situated further to the outside of the frame than the upper anchoring grooves.
4. A bed frame having anchoring grooves therein and a built-in spring core, said core comprising elastic springs with polygonal pitch-free end turns, tension members of elastic material connected to the corners of the elastic springs and anchoring elements at the ends of the tension members and inserted in said anchoring grooves, said bed frame being made of rectangular hollow profile of sheet metal, said anchoring grooves extending longitudinally and being formed on the upper and lower wall portions of said frame.
5. A bed frame as in claim 4, comprising an inwardly directed overlap formed at one corner of said sheet metal section so as to prevent said section from springing open.
6. A bed frame as in claim 1, further comprising distance stays joining the anchoring heads of said tension members together in a line.
7. A bed frame as in claim 1, said end turns of said elastic springs being square in outline.
8. A bed frame as in claim 1, said tension members comprising plastics material.
9. A bed frame as in claim 1, said anchoring grooves having a dovetail cross-section and said anchoring elements having a substantially triangular cross-section.
10. A bed frame having anchoring grooves therein and a built-in spring core, said core comprising elastic springs with polygonal pitch-free end turns, tension members of elastic material connected to the corners of the elastic springs and anchoring elements at the ends of the tension members and inserted in said anchoring grooves a hooklike lug being provided on the lower tension members, upholstery fabric being attached to said lug.
11. A bed frame as in claim 10, comprising a tension element attached to upholstery fabric and in engagement with said hook-like lug.
References Cited UNITED STATES PATENTS 3,161,408 12/1964 Molt 5256X BOBBY R. GAY, Primary Examiner JAMES C. MITCHELL, Assistant Examiner US. Cl. X.R.