RETRACTED POCKET SPRING MATTRESS; METHOD FOR MANUFACTURING OF A POCKET SPRING MATTRESS AND DEVICE FOR PRE-TENSIONING POCKETED COIL SPRINGS

Abstract: The present invention relates to a spring mattress comprising springs enclosed in casings, a so-called pocket mattress, and a method and a device for manufacturing such a mattress. The spring mattress according to the invention comprises a plurality of interconnected coil springs (1) enclosed in casings (2), for at least one of the springs, the casing portions arranged at the spring ends being moved towards each other, through the spring, and interconnected with the aid of connecting means.

Description: RETRACTED POCKET SPRING MATTRESS, METHOD FOR MANUFACTURING OF A POCKET SPRING MATTRESS AND DEVICE FOR PRE-TENSIONING POCKETED COIL SPRINGS Field of the Invention The present invention relates to a spring mattress comprising springs enclosed m casings, a so-called pocket spring mattress, as well as a method and a device 5 for manufacturing such a mattress . Background Art A common technique of making spring mattresses is the so-called pocket technique. This means that the 10 springs are enclosed m pockets, i.e. they are individually enclosed by a casing material . In this way, the springs will be relatively individually resilient so that they can flex individually without affecting the neighbouring springs and, thus, the comfort to the user 15 increases since his weight will thus be distributed more uniformly over the surface that receives the load. A drawback of such mattresses is, however, that it is difficult to make thin mattresses. If the length of the springs is reduced without a corresponding reduction 20 of the width, the spring will, especially v/hen the length approaches the length of the diameter of the spring, have a tendency to turn m the casing, which dramatically deteriorates the comfort of the mattress. When such mattresses are to be manufactured, the existing technique 25 requires a much larger number of springs. Consequently the manufacture will be considerably more expensive and more complicated. Besides it is difficult to prevent such mattresses from also oemg stiffer since too thin spring wire cannot be used. 30 For these reasons, it has not been possible to use spring mattresses for many purposes where thinner mattresses are required, such as for bed mattresses, seat cushions and the like. In spite of this, spring mattresses have several properties making it desirable to use them also m these contexts, such as excellent comfort, individual flexibility, a long life and easy and inexpensive manufacture. Obηect of the Invention It is therefore an obiect of the present invention to provide a spring mattress of the type mentioned by way of introduction, as well as a method and a device for manufacturing the same, m which the above drawbacks are obviated wholly or at least partly. This obnect is achieved by a spring mattress and a method for manufacturing the same according to the appended claims. Brief Description of the Drawings In the accompanying drawings Fig. 1 illustrates a device for manuf cturing a mattress according to an embodiment of the invention; Fig. 2 illustrates a mattress according to an embo- diment of the invention; Fig. 3 is a schematic sectional view of the device m Fig. 1 from above; Fig. 4a is a schematic sectional view of the device m Fig. 1, seen from the side, the inserting means being inserted past the abutment member; and Fig. 4a is a schematic sectional side view of a finished spring element according to the invention. Description of the Preferred Embodiments For the purpose of exemplification, the invention will now be described m more detail by way of an embodiment and with reference to the accompanying drawings. A spring mattress according to the invention comprises a plurality of interconnected coil springs 1 enclosed m casings 2. The casing is suitably made of a, preferably weldable, textile material, but also other materials such as different types of plastic materials can be used. It is also possible to use non-weldable textile materials, such as cotton cloth. Such mattresses, so-called pocket spring mattresses, are previously known, and the manufacture thereof is not part of the present invention. Normally, strings of interconnected coil springs m casings are manufactured automatically, whereupon these strings are cut m suitable lengths and joined side by side to form mattresses. According to the invention, for at least one of the springs, the casing portions arranged at the spring ends are moved towards each other, through the spring, and interconnected with the aid of connecting means to provide at least a certain degree of bias. Preferably, the casing portions are moved so far towards each other as to make contact, but it is, of course, possible to interconnect them also otherwise, by means of wire, a long clamp or the like. The connecting means may consist of a mechanical interconnecting element, such as a clamp, a rivet or the like, or a surface ]oιnt, such as a glue, a welding seam or the like. Other fixing elements are, however, also conceivable. The load exerted on the fixing elements is normally small since the fixing elements are only loaded if the mattress is unloaded, whereas there is no load at all if the mattress is loaded. The mattress according to the invention can be manufactured by the steps of enclosing springs m a casing material, biasing at least one of the springs and interconnecting the springs. By the step of biasing the springs is, m this case, meant moving casing portions arranged for the ends of the spring towards each other and interconnect them by means of connecting elements m such manner that the springs m the biased state have a smaller longitudinal extent than m the original, non- biased state. This bias can occur either immediately after encapsulating the springs m the casing material, i.e. before assembling them to form a mattress, or when the mattress has been assembled. Preferably, the bias occurs, however, when tne springs are located in strings, and conveniently bias of all springs m the mattress layer occurs m this way. A device for carrying out the method above comprises according to the invention an inserting means 11 and an abutment member 12 arranged at a distance therefrom. In use, springs are arranged so that one end is directed towards the inserting means and the other towards the abutment member. The inserting means is displaceable towards and away from tne abutment member for moving casing material at one spring end through the spring towards the casing material on the other side. Moreover, fixing means 13 are provided to form fixing members which interconnect the casing materials from both spring ends. Pre- ferably, the inserting means is movaole past the abutment member, and the fixing means is arranged on the opposite side thereof, as shown m the embodiment. In this manner, the inserting means can move the casing material out from both the front and the rear end of the spring through an opening m the abutment member while the abutment member prevents the spring from coming along. The fixing means can then fix together the casing materials with the aid of a mechanical fixing member, such as a clamp, or by means of surface joining, such as by gluing or welding. A system according to the invention may advantageously comprise a plurality of parallel devices, such as two devices operating m parallel, which is shown in the embodiment. Fig. 3 is a top plan view of the device according to this embodiment of the invention, m a position where the inserting means 11 are not inserted towards the abutment member 12. Fig. 4a illustrates the same device, but seen from the side, with the inserting means 11 m a position where it is inserted past and through the abutment member 12. The casing material 2 is made to come along and can be fixed together with a clamp or the like by the fixing means 13. A finished spring element according to the invention is also shown schematically in Fig. 4b. It goes without saying that also other types of fixing means can be used. It is also possible to use a mov- able abutment member, m which case means on both sides of the spring are pressed towards each other, whereupon fastening, welding or equivalent interconnecting can take place. In this manner, the freedom of choice when placing the fixing element will, however, be affected. Coil springs of many sizes can be used m connection with the present invention, and essentially any size of springs may be used. It is, however, preferable to use springs having a diameter of 2-10 cm, most preferred apout 6 cm. Moreover, it is preferred for the bias of the springs to be carried out so that the length of the springs m the biased state is smaller than 2/3 of the length of the same springs m the non-biased, original state, preferably smaller than 1/2. Moreover it is pre- ferred for the ratio of spring length to spring diameter m the biased state to be smaller than 2, preferably smaller than 1, most preferably smaller than 1/2. As mentioned above, the casings with springs are arranged preferably m successive rows, after which such rows are fixed to each other side by side, as indicated m Fig. 2. Preferably, the rows are fixed to each other at 2-3 fixing points distributed m the vertical direction m front of each spring. It goes without saying that a smaller or larger number of fixing points is possible. It is also possible to arrange an extended fixing line essentially parallel with the longitudinal direction of the springs instead of a plurality of fixing points. The interconnection of rows can take place by welding or gluing. Also such interconnecting can, however, alternative- ly be effected by means of clamps, Velcro tape or m some other convenient manner. With the inventive mattress, controlling of the spring is achieved, which is thus prevented from turning or the like. In this way, it is possible to make very thin mattresses, optionally down to a thicKness of one or a few centimetres. The invention thus is well suited for seat cushions, bed mattresses to be placed on top of other mattresses and similar applications where thin mattresses are required. It is very advantageous to be able to make bed mattresses of coil springs in this manner, not only to be able to make them thinner, thereby increasing their comfort, but also since springs are normally not subject to fatigue as time goes by, as are polyethylene and like materials. Mattresses according to the invention can be made very light, soft and comfort - able, but also, owing to the bias, very stiff and hard, as desired. By means of the invention, the height of the spring elements can easily be controlled by varying the position of the fixing member. The more the casing portions from the spring ends are moved towards each other and the more they are made to overlap when interconnected, the thinner and more compact the mattress. In this way it is also easy to provide different thickness m different portions of the mattress, or to provide mattresses having diffe- rent thicknesses, without having to change anything m the manufacturing process but the interconnection. The manufacture will thus be very flexible and controllable. Particularly, it is possible to provide mattresses which are bowl -shaped or the like for use as seat cushions or other mattresses intended to be used as seats. Similar changes m height can also be used m other mattresses to control the user's position on the mattress. By the casing material being pulled together over the springs according to the invention, tne entire mat- tress is also pulled together to some extent. As a result, the mattress is stabilised, and no frame or the like is necessary. Furthermore, the pulling together may force the springs to mesh somewhat while the casing material is arranged between them. This is desirable since this prevents the mattress from making noise that arises when uncovered spring turns strike against each other. The invention has been described above by way of an embodiment. Several variants of the invention are, however, conceivable. For instance, it is possible to use, as mentioned above, other types of fixing elements, as well as other casing materials, spring sizes etc. Fur- thermore the device and method can be designed m different ways. Such close variants must be considered to be comprised by the invention as defined m the appended claims .

Claims: CLAIMS 1. A spring mattress comprising a plurality of interconnected coil springs (1) enclosed m casings (2), for at least one of the springs, the casing portions arranged at the ends of the spring being moved towards each other, through the spring, and interconnected with the aid of connecting means, c h a r a c t e r i s e d m that the interconnection of the casing portions at the ends of the spring is such that the spring is biased. 2. A spring mattress as claimed in claim 1, wherein the casing portions are moved so far towards each other as to contact each other. 3. A spring mattress as claimed m claim 2, wherein the connecting means is arranged m such manner as to provide a desired overlap between the casing portions, the thus-obtained overlap determining the bias of the spring . 4. A spring mattress as claimed m claim 2 or 3 , wherein the connecting means is a mechanical connecting element, preferably a clamp. 5. A spring mattress as claimed m claim 2 or 3 , wherein the connecting means is a surface joint, such as a glue, a welding seam or the like. 6. A spring mattress as claimed m any one of tne preceding claims, wherein the casing is a, preferably weldable, textile material. 7. A spring mattress as claimed m any one of the preceding claims, wherein the spring is biased so that the length of the spring m the biased state is smaller than 2/3 of the length of the same spring m a non-biased state, preferably smaller than 1/2. 8. A spring mattress as claimed in any one of the preceding claims, wherein the ratio of spring length to spring diameter m the biased state is smaller than 2, preferably smaller than 1, and most preferably smaller than 1/2. 9. A spring mattress as claimed m any one of the preceding claims, comprising a plurality of biased springs, wherein at least some of the springs are differently biased. 10. A spring mattress as claimed claim 9, wherein the springs are differently biased so as to form portions of the mattress of varying thickness . 11. A method for manufacturing a spring mattress comprising a plurality of interconnected coil springs (1) enclosed m casings (2), comprising the steps of enclosing the springs m a casing material; biasing at least one of the springs; and interconnecting the springs, the step of biasing the springs comprising the partial steps of moving casing portions arranged for the ends of the spring towards each other and interconnecting them by means of connecting elements. 12. A method as claimed m claim 11, wherein the casing portions are moved so far towards each as to contact each other. 13. A method as claimed m claim 12, wherein the bias of the springs is controlled by the positioning of the connecting means, and the thus-provided overlap between the casing portions. 14. A method as claimed m claim 12 or 13 , wherein the connecting means is a mechanical interconnecting element, preferably a clamp. 15. A method as claimed m claim 12 or 13, wnerein the connecting means is a surface joint, such a glue, a welding seam or the like. 16. A method as claimed m any one of claims 11-15, wherein springs enclosed m casing material are first interconnected successively m strings, whereupon bias occurs and finally said strings are interconnected m a juxtaposed manner. 17. A method as claimed m any one of claims 11-16, wherein essentially all the springs m the mattress are biased . 18. A method as claimed m any one of claims 11-17, 5 wherein the step of biasing is carried out m such manner that the length of the spring m the biased state is smaller than 2/3 of the length of the same spring m a non-biased state, preferably smaller than 1/2. 19. A method as claimed m any one of claims 11-18, 0 wherein the step of biasing is carried out m such manner that the ratio of spring length to spring diameter m the biased state is smaller than 2, preferably smaller than 1, and most preferably smaller than 1/2. 20. A method as claimed m any one of claims 11-13, 5 wherein a plurality of springs are biased, the springs being biased to different extents. 21. A spring mattress as claimed m claim 20, wherein the springs are biased so as to form portions of the mattress of varying thickness . 0 22. A device for biasing coil springs (1) enclosed m casings (2), c h a r a c t e r i s e d by an inserting means and a counteracting means arranged at a distance therefrom, the inserting means and the counteracting means being adapted to perform a relative displace- 5 ment towards and away from each other to bring casing materials at the spring ends of a spring arranged tnere- between towards each other through the spring, and fixing means for arranging fixing members whic.i interconnect the thus brought -together casing materials from the two 0 spring ends. 23. A device as claimed m claim 22, wherein the counteracting means is a passive abutment member, the inserting means being displaceable towards and away t from said abutment member. 5 24. A device as claimed m claim 23, wherein the inserting means is displaceable past the abutment member, and the fixing means is arranged on the opposite side of the abutment member. 25. A device as claimed m claim 24, wnerem the overlap, i.e. how far the inserting means is displaceable past the abutment member, is controllable. 26. A device as claimed m any one of claims 22-25, wherein the fixing means is adapted to fix brought-toge- ther casing material with the aid of a mechanical fixing member, such as a clamp. 27. A device as claimed m any one of claims 22-25, wherein the fixing means is adapted to fix brought- together casing material with the aid of a surface-connecting fixing member, such as by gluing or welding.

Inventors: EDLING KENNETH, EDLING, KENNETH
Applicants: EDLING KENNETH, STJERNFJAEDRAR AB, EDLING, KENNETH
Application year: 2000
Main classification: B68G9
IPC codes: A47C23, A47C27, B68G9