US 3821823 A
Description (OCR text may contain errors)
United States Patent [191 Krier et al.
UPHOLSTERED BODY AND METHOD OF MAKING SAME Inventors: Phillip Krier, Stuttgart-Schonberg;
Lothar Fendler, Gerokstrasse Stuttgart, both of Germany Assignee: Mirabed AG, Zug, Switzerland Filed: May 4, 1972 Appl. No.: 250,328
Related US. Application Data.
Division of 881'. No. 753,391, Aug. 19, 1968, Pat. No. 3,660,876.
Foreign Application Priority Data [111 13,821,823 1 July2,'19f( 1 Primary ExaminrCasmir A. Nunbcrg Attorney, Agent, or FirmJames S. Hight, Jr. et al.
57 ABSTRACT An upholstered body, especially mattress and seat for automobiles, andmethod of making the same, according to which a core body of coil springs has a seamless 1967 r. Aug Germany 1 G 50909 cover of foamed material, for instance, of polyester, or us. Cl. 5/351 5/269 I polyethe around Said corebody' Int. Cl A47c 23/04, A470 25/00 5 Chimss Drawing Figures Field of Search 5/267, 269, 351; 29/911 V 3 24 Zitil'i i i Z \v A W25 UPI-IOLSTERED BODY AND METHOD OF MAKING SAME This is a division of application Ser. No. 753,391-K- rier et al, filed Aug. 19, 1968, now U.S. Pat. No. 3,660,876, May 9, 1972.
The present invention relates to a mattress and method of making the same, according to which a spring core is provided with a cover of foam material.
It is known to cover spring cores of mattresses with a two-sectional hood of foam material, which hood is,- prior to covering the spring core, cut so as to form a development and is then glued or cemented. This method has the drawback that it is awkward and expensive. Furthermore, the gluing areas of the cover of foam material are easily damaged.
It is, therefore, an object of the present invention to provide a method of making a mattress which will assure a simple and complete cover of a spring core in a minimum of time. i
It is another object of this invention to provide a mattress and method of making the same, according to which in one working step with the application of the cover on the spring core, the cover is additionally provided with a coating, for instance, of textile material.
It is also an object of this invention to provide a mattress which can easily be reinforced at those areas which are particularly exposed to damage.
These and other objects and advantages of the invention will appear more clearly from the following specification, in connection with the accompanying drawings, in which:
FIG. 1 diagrammatically illustrates a cross section through a mattress according to the invention.
FIG. 2 shows a section through a further embodiment of a mattress according to the invention.
FIG. 3 is a top view of a cutout portion of a spring core of a mattress according to the invention.
FIG. 4 is a perspective view of the springs shown in FIG. 1.
FIG. 5 illustrates, similar to FIG. 3, a further embodiment of a spring core according to the invention The method according to the present invention according to which a spring core is covered with a cover of foam material, is characterized in that the prefabricated spring core in a foaming process is provided with a cover closed in itself of polyester, polyether, or a similar soft foam material. Due to the fact that the foam layer foams directly on the spring core and thus is shaped accordingly, the covering or coating of the spring core can be effected in a minimum of time. The spring core itself forms the inner form of the cover so that the latter will precisely fit. Furthermore, the cover prepared according to the invention is completely seamless so that even when being relatively thin it will have a considerable strength.
The method according to the invention can easily be practiced when the spring core, prior to the foaming of the layer of foam material is covered with textile material, synthetic material, or the like so that, at any rate, the layer of foam material will be prevented from passing between the springs or the windings thereof.
According to a further development of the invention, the prefabricated spring core is,in a closed foaming mold, provided with a cover so that the outer shape of the cover will beprecisely predetermined.
According to a particularly advantageous step of the method according to the present invention, the spring core is, prior to the foaming on of the layer of foam material, provided with a cover, for instance, of textile fabric, since such textile fabric cover enters into an intimate connection with the foam material in such a way that the air entrapped in the spring core can escape during the foaming process. This air core will then, during the further foaming operation, produce a counter pressure against the foaming pressure. The thus formed air core is therefore during the manufacture of the mattress very advantageous during the foaming operation.
In certain instances it is advantageous to provide the edges of the mattress with a reinforcement. This reinforcement may, in conformity with a further feature of the invention, be applied in the form of a reinforcing fabric or the like which intimately combines with the soft foam. By means of this reinforcement, certain edges of the mattress may be designed in a simple mannerv as form retaining edges. Textilefabric, wire fabric, fabric of synthetic material, wood or metal parts, are particularly suitable for this reinforcement.
According to a further feature of the present inven tion, a coating layer for the spring core, for instance, a textile fabric, is inserted in the foaming mold, and the spring core is, in said mold,,covered with the soft foam layer so that the coating layer firmly combines with the soft foam layer. In this way it is possible in a single operation to provide the spring core with the cover as well as with fabric material, for instance, cotton drill.
The cover layer is, due to its fixed connection with the soft foam cover, prevented from slipping. Due to this cover, also the reinforcing areas are covered by the inserted fabric. In order to make possible that the covering layer is precisely in conformity with the foaming mold, said covering layer is pressed against the inner wall of the mold by gas under pressure. This gas filling is, advantageously, during the introduction of soft foam, withdrawn to the extent to which the softfoam is introduced into the mold.
According to still another feature of the invention, the soft foam layer is thicker or thinner at the side of the spring core than it is at the two large surfaces of the spring core. The spring core may have a height of 7.5 centimeters, and the soft foam layer at the top and bottom sidemay have a height of approximately 3 centi meters, while the softfoam layer at the sides may have a thickness of approximately 2 centimeters. The thinner side parts of the soft foam layer have a higher weight per volume curing the foaming operation and thereby become stiffer so that a laterial stiffening, and consequently an increase in the form stability will be assured.
Referring now to the drawings in detail, a spring core 24 (FIG. 1) is providedwith a cover 25 which may be formed, for instance, by an envelope of nettle cloth, jute, or the like. The thus formed spring core 24' is placed in a foaming mold 26 which comprises two mold sections 27 and .28. Between the inner surface of the foaming mold 26 and the outer surface of the cover 25, there is provided a gap 29 extending all the way around said spring core 24. The height of this gap corresponds to the desired height of the layer of foam material. Thus, the spring core 24 is floatingly arranged, and this floating mounting may be realized by pins or similar spacer means (not shown in the drawings). The material to be foamed is then introduced into the closed mold composed of the sections 27 and 28 through one or more feeding passages 30 and is foamed directly rial closed in itself forms the surface of the spring core. When the first foaming tests for mattresses with a spring core were carried out, it was found that during the foaming, the textile fabric which surrounds the spring core enters an intimate and solid connection with the foam material so'that the air in the spring core will during the foaming operation be enclosed in an airtight manner with the result that an air core forms. This air core will during the foaming operation develop a counter pressure against the foam pressure during the foaming operation to such an extent that an undesired compression of the spring core will be prevented. Consequently, form-true foam bodies properly corresponding to the desired form are obtained in which the spring core is firmly embedded FIG-2 shows a further embodiment of a mattress with a preferred size ratio between the spring core 24a and the cover 32 of foam material. At the top and bottom side, the layer 32 of foam material has a thickness which is only slightly less than .half the height of the spring core 240;. The lateral parts 33 of. the foam materiallayer 32 on the other hand, are only slightly thicker than a fourth of the height of the spring core 24a. These lateral parts 33, however, have a greater density and thus havean increased stiffness or rigidity. In the edges of the mattress, reinforcements 34 in the form of textile fabric or the like are embedded in the layer32 of foam material so that the mattress will have form retaining edges. The entire layer 32 of foam material is provided with a cover or envelope 35, the inner surface of which is, over its entire surface, firmly connected with the layer 32 of foam material and, if desired, with the reinforcements 34.
As will be evident from FIGS. 3 and 4, the spring core of the mattress according to FIG. 2 comprises a plurality of springs l'which are arranged adjacent to each other in the longitudinal direction indicated by the arrow 3 and in I transverse direction indicated by the arrow '4, and which whenlooking down on the spring core 24a have an annular or corner shape. The springs are.in the transverse direction (arrow 4) of the spring core, arranged adjacent to eachother in rows 5 whereas in longitudinal direction of the spring core (arrow 3) are arranged one after the other in rows 6,
- ways two fine wires 13 are arranged directly adjacent In view of the rectangularcross-section of the springs in combination with the outermost coils thereof respectively located in a plane parallel to the plane of the spring core, there will after the foaming of the cover 32 be obtained a very high form stability ofthe spring core and, if desired, a firm connection between the cover 32 of the foam material and the spring core 24a. The two end legs 17 of each spring are inclined with regard to the center of the spring core so that the cover 32 of foam material or the cover 25'cannot be damaged.
-As will be evident from FIG. 3, the springs I when seen from the top have a substantially trapezoidal shape while each two legs 15, 16; 20, 21 are forming a right angle with regard to each other and the other two oppositely located legs 18, 19 define with each other an angle of slightly less than 20.
The springs 1 of the spring rows 6, 7 extending in the longitudinal direction (arrow 3).of the spring core are arranged in the respective rows-6, 7 in a position corresponding to each other. The springs 1 of the rows 6, 7 which extend in the longitudinal direction (arrow 3) and are adjacent'to each other in the transverse direction (arrow 4) are offset with regard to each other by 90 in such a way that, for instance, the spring end legs 17 of said adjacent rows 6, 7 are offset to each other by 90. The'springs of 'eachspring row extending in the longitudinal direction (arrow 3) of the spring core are arranged in the same position, but are offset with regard to the springs of the adjacent spring row by90". In'this way, the legs parallel to the plane of the spring core and respectively pertaining to two adjacent spring rows are located directly adjacent to each other while the legs 15, 16 which are arranged along a straight line one behind the otherare interconnected by fine wires 13 in such a way that according to FIGS. 3 and 4, al
to each other. This brings about that the legs 15, 16 of the adjacent spring rows can in response to a load act- 7. The individual springs are interconnected by fine wires 8 10 extending in transverse direction.(arrow 4) and furthermore interconnected by fine wires 11 13 extending in longitudinal direction (arrow 3).
As illustrated in FIG. 4, the outermost spring coils 14 of the springs 1 are located in planes which are parallel to the plane of the spring core. These outermost coils are formed by three legs 15 16 arranged at a right angle with regard to each other. The next two legs 18,19 adjacent to the outermost spring coil 14 extend at an inclination with regard to the plane of the spring core. The then adjacent legs 20, 21 of the spring 1 are again located in a plane parallel to the plane of the I spring core. The inclination of the legs l8, 19 is so se- 1 lected that the distance of the legs 20, 21; 15, 16 which ing upon the spring move toward each other and thereby can support each other.
The fact that the fine wires will cover the entire extension of the spring core enclose rectangulars of substantially identical sizes which respectively correspond to the plan view of two springs brings about that there will be obtaineda very uniform" structure and thereby a uniform spring effect and a uniform load distribution over the cover 32. The longitudinal central area of the spring core is reinforced by the fine wire 13 arranged in pairs adjacent to each other so that also in the central area a sufficient force of the spring core will be assured. The asymmetry of the springs is balanced with regard to each other by the offset arrangement of the individual springs. I I r The springs l are so arranged that in the longitudinal direction of the spring core (arrow 3) and in the transverse direction thereof (arrow 4) always two legs 16, 20; 15,16; 21, 20, are located along a straight line and plane parallel to the plane of the spring ,core one behind the other. The helical'fine wires 8 l3 arewound around these just-mentioned legs of the spring 1. Within themarginal area 2 of the spring core, the outermost windingsl4 are interconnectedby means of two fine wires 8, 9 ll, 12 pointing in the same direction whereby an additional reinforcement of the marginal area 2 of the spring core will be assured.
Instead of reinforcing the marginal area 2 of the spring core by means of two or more fine wires 8, 9;
11, 12, the marginal area 2 of the spring core may also be reinforced by one or more flat steel frames 22, as shown in FIG. 5. Such frame 22 is connected to the marginal springs located in the marginal area and is preferably embedded in the cover of foam material.
The ends 23 of the fine wires 8 13 are bent at a right angle and are wound around the legs of the corresponding springs 1, said legs forming the marginal area 2 of the spring core.
The soft foam may be so foamed upon the cover 25 of the spring core that it combines with the cover in such a way that this layer will have great strength, especially against wear. Between the spring core and the soft foam layer proper there is thus formed an intermediate layer which will assure a safe support on the spring core.
It is, of course, to be understood that the present invention is, by no means, limited to the particular arrangements shown in the drawings, but also permits modifications, the invention being determined by the scope of the appended claims.
It is furthermore to be understood, that the method according to the invention is not limited to the making of mattresses, but also covers the making of upholstered bodies, such as seats for automobiles, and the like.
What we claim is:
1. An upholstered body which includes: a core body comprising a plurality of coiled wire springs, each coil of said springs when seen in axial direction thereof having legs of an approximately quadrangular. contour while the outermost coils are at least partially located in a plane defining a major plane of the core body, said coils being arranged in superimposed spaced planes and in rows extending in a first direction and also in rows extending in a second direction transverse to said first direction, fine connection helical wire means having a diameter considerably less than the wire of said spring coils and interconnecting coil legs extending in the same direction and located in substantially the same plane while pertaining to different coils, wrapping means adjacent to the outer coils of said coiled springs and enclosing said coiled wire springs and a cover of soft foam material fully enclosing said wrapping means and said spring core.
2. An upholstered body according to claim 1, which includes a flat metallic frame connected to the outermost coils of said coil springs and forming a part of said spring core.
3. An upholstered body according to claim 1, in which the outermost coils which at least in part define a marginal surface of the core body comprise three legs angularly arranged with regard to each other.
4. An upholstered body according to claim 1, in which each of the springs is offset by approximately with regard to at least one adjacent spring.
5. An upholstered body according to claim 1, in which the ends of said springs are inclined toward the center of the core body.