Separated pocket spring mattress with cut through string, and method and apparatus for production of such mattress

Abstract

A spring mattress with longitudinal strings comprising a plurality of interconnected coil springs (1) enclosed in covers (2) is described, wherein a plurality of such parallel strings are arranged side by side and interconnected by surface attachment between abutting surfaces. Furthermore, a slit is provided between at least two springs located adjacent to one another within the same string, which slit allows an increased interjacent separation distance (SA) to be formed between, said adjacent springs. Also described are a method and a device, respectively, for manufacturing a corresponding mattress.

Claims

1. A spring mattress with longitudinal strings, the spring mattress comprising: a plurality of interconnected coil springs enclosed in covers, and a plurality of parallel strings arranged side by side and interconnected by a surface attachment between abutting surfaces of adjacent strings, wherein a slit is provided between at least two coil springs located adjacent to one another within the same string, the slit in combination with the surface attachment allowing an increased interjacent separation distance to be formed between said adjacent coil springs.

2. The spring mattress as claimed in claim 1, wherein the slit is provided such that the slit is completely enclosed between an upper and a lower part of the string.

3. The spring mattress as claimed in claim 1, wherein the slit is provided between all adjacent coil springs in all the strings arranged in parallel.

4. The spring mattress as claimed in claim 1, wherein the slit is provided only between some of the adjacent coil springs of at least one string to obtain zones with different properties across the mattress.

5. The spring mattress as claimed in claim 1, wherein the covers are joined together on both sides along the slit to close the covers along the slit.

6. The spring mattress as claimed in claim 1, wherein the surface attachment configured to interconnect the strings includes at least one of gluing and welding.

7. The spring mattress as claimed in claim 1, wherein the separation distance exceeds about 10% of the diameter of the largest spiral turn of the adjacent coil springs.

8. The spring mattress as claimed in claim 1, wherein the separation distance exceeds 1 cm.

9. The spring mattress as claimed in claim 1, wherein a spring density of the spring mattress along a direction of slits in a string is less than 15 springs per meter.

10. The spring mattress as claimed in claim 1, wherein the covers are made from a textile fabric that can be welded.

11. A method of manufacturing a spring mattress, the method comprising: arranging coil springs enclosed in covers in longitudinal strings, and interconnecting a plurality of parallel strings side by side by a surface attachment between abutting surfaces of adjacent strings, and providing a slit between at least two coil springs located adjacent to one another within the same string such that the slit in combination with the surface attachment allows an increased interjacent separation distance to be formed between the adjacent coil springs.

12. The method as claimed in claim 11, wherein the slit is provided such that the slit is completely enclosed between an upper and a lower part of the string.

13. The method as claimed in claim 11, further comprising joining together a cover material on both sides along the slit to close the covers along the slit, wherein the cover material is joined before providing the slit.

14. The method as claimed in claim 11, wherein the plurality of parallel strings are interconnected side by side by at least one of gluing and welding.

15. The method as claimed in claim 11, wherein arranging the coil springs further comprises: arranging a strip of a cover material such that it is folded over the coil springs arranged in succession therebetween, providing a longitudinal joining line at the open end of the folded strip, and arranging, before or after providing the longitudinal joining line, at least one transverse joining line between adjacent pair of coil springs.

16. The method as claimed in claim 15, wherein the slit between adjacently located coil springs is provided at the same time as or directly after arranging the at least one transverse joining line.

17. An apparatus for manufacturing a spring mattress, the apparatus comprising: means for arranging coil springs such that the coil springs are enclosed in covers in longitudinal strings, and means for interconnecting a plurality of parallel strings side by side by surface attachment between abutting surfaces of adjacent strings, wherein the apparatus further includes means for providing a slit between at least two coil springs located adjacent to one another within a same string such that the slit in combination with the surface attachment allows an increased interjacent separation distance to be formed between the adjacent coil springs.

18. The apparatus as claimed in claim 17, wherein the means for providing the slit between at least two coil springs located adjacent to one another within the same string are configured to arrange the slit such that the slit is completely enclosed between an upper and a lower part of the string.

19. The apparatus as claimed in claim 17, further comprising means for joining together a cover material on both sides along the slit, to close the covers along the slit.

20. The apparatus as claimed in claim 17, wherein the means for interconnecting a plurality of parallel strings side by side by surface attachment between abutting surfaces are configured to effect said interconnection by at least one of gluing and welding.

21. The apparatus as claimed in claim 17, wherein the means for arranging the coil springs comprise: means for arranging a strip of a cover material so that the cover material is folded over the coil springs arranged in succession therebetween, means for arranging a longitudinal joining line at an open end of the folded strip, and means for arranging at least one transverse joining line between each pair of adjacent springs.

22. The apparatus as claimed in claim 21, wherein the means for providing the slit is a cutting tool configured to move in a direction of the cover material.

23. The apparatus as claimed in claim 22, wherein the cutting tool is arranged adjacent to the means for arranging the at least one transverse joining line between each adjacent pair of springs and wherein the cutting tool is configured to operate jointly with the means for arranging the at least one transverse joining line.

24. The spring mattress as claimed in claim 1, wherein the separation distance exceeds about 15% of the diameter of the largest spiral turn of the adjacent coil springs.

25. The spring mattress as claimed in claim 1, wherein the separation distance exceeds about 20% of the diameter of the largest spiral turn of the adjacent coil springs.

26. The spring mattress as claimed in claim 1, wherein a spring density of the spring mattress along a direction of slits in a string is less than 13 springs per meter.

27. The spring mattress as claimed in claim 1, wherein each string of the plurality of parallel strings includes the plurality of coil springs enclosed in a continuous cover.

28. The spring mattress as claimed in claim 1, wherein the slit is a cut out opening in the enclosing cover of the string and at least a portion of the enclosing cover surrounding the slit is unbroken and continuous.

29. The method as claimed in claim 11, further comprising: interconnecting each string of the plurality of parallel strings including the coils springs enclosed in a continuous cover.

30. The method as claimed in claim 11, further comprising: providing the slit as a cut out opening in the enclosed cover of the string around at least a portion of the enclosing cover surrounding the slit, the portion of the enclosing cover surrounding the slit being unbroken and continuous.

31. The apparatus as claimed in claim 17, wherein the means for arranging coil springs arrange the coil springs such that the coil springs are enclosed in a continuous cover.

32. The apparatus as claimed in claim 17, wherein the means for providing the slit provide a slit that is a cut out opening in the enclosing cover of the string and at least a portion of the enclosing cover surrounding the slit is unbroken and continuous.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the annexed drawings:

(2) FIG. 1 is a perspective view of a part of a spring mattress designed in conformity with the invention;

(3) FIG. 2 is a side view of a string with enclosed springs to be used in a mattress in accordance with the invention, in a position before separation;

(4) FIG. 3 shows the string of FIG. 2, but in a position where the string has been separated;

(5) FIG. 4 is a plan view from above of a part of a mattress in accordance with one embodiment of the invention.

(6) FIG. 5 is a perspective view of a part of an apparatus, according to a first embodiment, for manufacturing a mattress in accordance with the invention;

(7) FIG. 6 is a perspective view of a part of an apparatus, according to a second embodiment, for manufacturing a mattress in accordance with the invention;

(8) FIG. 7 is a perspective view of a part of an apparatus, according to a third embodiment, for manufacturing a mattress in accordance with the invention;

(9) FIG. 8 is a perspective view of a part of an apparatus, according to a fourth embodiment, for manufacturing a mattress in accordance with the invention;

(10) FIG. 9 is a plan view from above of a mattress comprising different zones in accordance with one embodiment of the invention; and

(11) FIG. 10 is a side view of the mattress in FIG. 9.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(12) The invention will be described in the following for exemplifying purposes by way of embodiments and with reference to the accompanying drawings.

(13) A spring mattress in accordance with the invention comprises a plurality of interconnected coil springs 1, which are enclosed in covers 2, as shown in FIGS. 1-4. Suitably, the cover is made from a preferably weldable textile fabric but other materials, such as various types of plastic material, could equally well be used. It is likewise possible to use non-weldable textile fabrics, such as cotton fabrics. Normally, strings 3 of interconnected, cover-enclosed coil springs are manufactured automatically, whereupon the strips are cut into suitable lengths and joined together side by side to form mattresses.

(14) Preferably, the covers are dimensioned to ensure that the maximum enclosed height amounts to at least 3 cm and preferably to at least 5 cm.

(15) Coil springs of many different sizes could be used in conjunction with the present invention, and in principle any desired spring size, large or small, may be used. Preferably, however, springs are used having a diameter of 2-10 cm, and most preferably a diameter of about 6 cm. Preferably, the springs comprise at least four spiral turns and preferably fewer than 10 spiral turns. In addition, it is an advantage to manufacture the springs from helically coiled wires having a thickness in the range between 0.5 and 3.0 mm and preferably a wire thickness in the range of 1.5 to 2.2 mm.

(16) In the spring mattress in accordance with the invention a slit 4 is provided between at least two adjacent springs of at least one string. Preferably, the slit is provided in such manner that it is completely enclosed between the upper and the lower part of the string, this being achieved by the slit beginning a certain distance below the top of the string and ending a certain distance above the bottom of the string. This means that the string is still unbroken both at the top and at the bottom also after the slit has been formed. The slit allows the springs to be pulled apart, from the non-separated position shown in FIG. 2 to the separated position shown in FIG. 3, wherein an increased interjacent separation distance SA is formed between these adjacent springs. This will cause the slit to open, while the interconnecting remaining string material in the top and bottom part will be stretched out.

(17) Preferably, this type of slit is provided between essentially all adjacent springs of the string, and in essentially all the strings arranged in parallel with one another.

(18) The interjacent separation distance SA thus obtained preferably exceeds 10% of the diameter of the largest one of the spiral turns of the adjacent springs, and preferably it exceeds 15%, and most preferably exceeds 20%. In addition, the separation distance preferably exceeds 1 cm. These separation distances preferably are arranged between essentially all springs in the lengthwise direction of the mattress.

(19) Furthermore, it is advantageous for the cover material to be joined on both sides along the slit to close the covers along the slit. This improves the ability of the covers to withstand opening and eliminates the risk of the springs making their way out of the pockets during use. This can be achieved by providing the strings with two joining lines 5, such as weld joints or glue lines, for the joining together of the cover material on both sides of the slit 4. The joining lines can be provided either before or after the providing of the slit.

(20) Instead of several joining lines it is, however, also possible to have only one joining line, wherein the slit is provided exactly in the centre thereof so that the joining line still holds the cover material together on both sides of the slit.

(21) The joining lines, comprising for example weld or glue lines, as described above, can be provided as continuous lines or as spot weld seams of different size arranged along lines. Other types of joints are possible too, such as one or several stitched seams.

(22) The invention makes it possible to use less than 30 springs and preferably about 25 springs and most preferably about 22 springs in mattresses having a length in excess of 180 cm. It is also preferable that, in the mattresses in accordance with the invention, the density of springs in the lengthwise direction or directions, in which the separation distances are provided, is less than 15 springs per meter and preferably is less than 13 springs per meter.

(23) Furthermore, in the mattress in accordance with the invention several strings are arranged in parallel, and interconnected side by side by surface attachment joints 6 of abutting surfaces. The surface attachment can be achieved by gluing, welding or the like.

(24) In the manufacture of mattresses in accordance with the above, the following steps are carried out in any chosen order: arranging coil springs (1) in such manner that they are enclosed in covers (2) in longitudinal strings of cover material. This step in turn preferably comprises the partial steps of arranging a strip of a cover material so that it is folded over springs arranged in succession therebetween, providing a longitudinal weld 7 or glue line at the open end of the strip thus folded, and arranging, before or after the arranging of the longitudinal weld/glue line 7, at least one transversal weld 5 or glue line between adjacent springs 1 in each pair of springs; interconnecting a plurality of parallel strings side by side by surface attachment between abutting surfaces; this step is preferably carried out by gluing and/or welding; providing slits between at least two adjacent strings within the same string, and pulling out the string to separate the springs.

(25) Preferably, the step of providing the slits is carried out at the same time as, or directly after, the arranging of the at least one transverse weld/glue line between said springs.

(26) As already mentioned, the covers comprising springs are preferably arranged in successive rows, whereupon such rows are attached to one another side by side by surface attachment as indicated in FIG. 4. Preferably, the rows are attached to one another in 2-3 vertically spaced attachment points opposite the associated spring. A larger or smaller number of attachment points could of course also be used. It is likewise possible to use one long attachment line extending essentially in parallel with the longitudinal direction of the springs instead of several, shorter attachment points. It is likewise possible to join together the strings by means of a string of glue or the like extending in the direction of extension of the strips. The interconnection of rows side by side in succession could be effected by welding or gluing, as mentioned previously. However, this interconnection can be achieved using other alternative forms of surface attachment, such as clamps, Velcro tapes or some other suitable joining-together method.

(27) By joining-together the strings in this way opposite the springs in the respective string, the separation distances will be positioned in alignment with one another, as indicated in the embodiment shown in FIG. 4. This position is the preferred one, although it is likewise possible to arrange the strings in such a manner that the springs will be positioned offset relative to one another. In the latter case, the springs as a whole may be arranged, if desirable, more densely across the mattress than is the case in conventional pocket-spring mattresses.

(28) It is also possible to use different separation distances in different zones or areas of the mattress and to use for example larger separation distances in areas that in normal use of the mattress are less exposed to load, and smaller separation distances in areas exposed to more heavy loads. This can be controlled by determining between which springs slits are provided, how long the slits are, where on the strings the slits are provided, how the strings are joined together, etc.

(29) One example of a mattress comprising different zones is shown in FIGS. 9 and 10. In this example, the mattress comprises several different zones in the lengthwise direction thereof. In a first zone I located at the head end of the mattress, the strings are cut through between the springs, in the manner described in detail above. In normal use, this zone is subjected to the load of the user's upper body, from the waist up. In a second zone II, the strings are not cut through. This zone corresponds to the curve of the user's back. Thereafter, a short zone III is provided in which the strings are cut trough. This zone corresponds to the buttocks of the user. Next, another zone IV in which the strings are not cut through is provided, which zone corresponds to the thighs of the user. Finally, the foot end of the bed comprises a large, cut-through zone V, which corresponds to the legs of the user from the thighs down. This bed offers support for the curve of the user's back and the thighs, while allowing the other body parts to sink deeper into a softer mattress. In this way, a more comfortable mattress is obtained, in which the loads on all parts of the body are more evenly distributed.

(30) However, many other variants of zone division are conceivable. It is possible, for example, to divide the mattress into a larger or smaller number of zones in the lengthwise direction of the mattress. One example is using only three zones. Furthermore, it is possible to divide the mattress into zones also in the latitudinal direction, by interconnecting strings with non-identical cuts between the springs. In this connection, the springs may also comprise different numbers of springs. This allows, for example, a mattress to be obtained which is softer in the middle (with cut-through strings) and harder towards the edges (with less cut-through strings). Moreover, when manufacturing double beds, for instance, non-homogeneous strings may be used in the different mattress halves, thus to better adapt the mattress for the use of two persons with different needs and desires.

(31) It is possible, of course, to obtain corresponding zone divisions using mattresses that are instead formed of transversal strings and not of the longitudinal strings described above.

(32) An apparatus for manufacturing a spring mattress as described above and for carrying out the above-related method may comprise: means for arranging coil springs 1 enclosed in covers 2 in longitudinal strings 3 of a cover material. Means of this kind are previously known within the field and have been used previously to manufacture pocket-spring mattresses. means for interconnecting a plurality of parallel strings side by side by surface attachment between abutting surfaces. Means of this kind are also previously well-known within the field and have previously been used to manufacture pocket-spring mattresses. means for providing a slit between at least two springs located adjacent to one another within the same string, which slit allows an increased interjacent separation distance (SA) to be formed between said adjacent springs. Means of this kind have not previously been used in this type of apparatus and will be described in greater detail below.

(33) The means for arranging coil springs in such manner that they are enclosed in covers advantageously comprises means for arranging a strip of a cover material 2 so that it is folded over springs 1 arranged in succession therebetween, means for arranging a joining line 7, such as a weld or glue line, at the open end of the strip thus folded, and means for arranging at least one transverse joining line 5, such as a weld or glue line, between pairs of adjacent springs of the strings.

(34) The means for arranging slits can consist of a cutting tool 10 arranged to be moveable towards the cover material, as shown in FIG. 5. In this case, the cutting tool consists of a rotating cutting tool, comprising a circular cutting edge, which can be rotated during operation. Furthermore, the cutting tool can be moveable in a direction towards and away from a working table on which the cover material 2 is positioned during use, as indicated by the arrow R1. Preferably, the cutting tool is arranged directly adjacent the means for arranging transverse joining lines 5. Said means may consist, for example, of welding equipment 20 for ultrasonic welding, with two welding elements 21. The welding equipment is preferably moveable in the same way as the cutting tool, but independently thereof, as indicated by the arrow R2. This allows the welding equipment to be lowered towards the cover material to create two parallel spot weld lines 5, and the cutting tool to be lowered towards the cover material to create a slit 4 therebetween, while at the same time the cover material is displaced relatively to the welding equipment and the cutting tool, as indicated by the arrow R3. However, it is equally possible instead to cause the welding equipment 20 and the cutting tool 10 to be displaced in the direction R3 and the cover material to remain still.

(35) In this embodiment, the welding equipment tools the cover material first, and only thereafter is the slit formed by the cutting tool. The opposite approach is also possible, i.e. the slit is formed first, and only thereafter are welds provided along the edges of the slit sides.

(36) As an alternative to the embodiment described above with reference to FIG. 5, a welding equipment 20 which comprises only one welding element 21 may be used, as shown in FIG. 6. As a result thereof, only one joining line 5 is formed, which is separated by the slit 4. In this case, it is an advantage to provide a slightly wider joining line, to make sure that a satisfactory interconnection is obtained on both sides of the slit. In other respects, the same arguments as above apply regarding the use of the equipment and the interrelation between the welding equipment, cutting tool and cover material.

(37) Instead of a rotating cutting tool, as described above with reference to FIGS. 5 and 6, a non-rotating tool 10 may be used, as shown in FIG. 7. This tool is movable towards and away from the cover material in the way described above. The non-rotating tool may have a flat cutting edge 11, as shown in FIG. 7, but other designs are also conceivable. For instance, the cutting edge may be concave, convex, serrated, corrugated or the like. Moreover, the cutting edge can be arranged parallel to the cover material, as shown in FIG. 7, or more or less tilted relatively to said plane. The cutting tool may also be arranged before or after the welding equipment. In the case where multiple welding elements are used it is, however, also possible to arrange the cutting tool at the same level as the welding elements and between them, as shown in FIG. 7. This allows a very compact design of the apparatus.

(38) Furthermore, it is possible to arrange the cutting tool 10 and the joining tool 20 on opposite sides of the cover material, as shown in the working example in FIG. 8. More space is thus available for each tool and, consequently, their manufacture and use is simplified.

(39) As described above, it is possible to use joining tools, such as welding means, which are displaceable along a line and, thus, are continuously or intermittently activated to form the joining line. However, it is also conceivable to use joining tools 20 whose extension in the longitudinal direction corresponds to that of the joining line. One example of such a tool is shown schematically in FIG. 8. In an embodiment of this kind, the joining tool does not have to be displaced along the joining line, but only up and down to stamp the joining line between the springs. This operation can be carried out considerably faster, thus allowing the rate of production to be increased.

(40) The apparatuses adapted to cut slits according to the above description can be integrated with most of the prior-art manufacturing equipment for manufacturing pocket-spring mattresses. It is also conceivable, however, to arrange the cutting tool separately from the rest of the manufacturing equipment. Thus, the welding equipment can be located before the cutting equipment in the direction of travel of the strings, wherein detecting means can be used to detect the joining lines prior to the cutting operation. Different types of detecting means are conceivable, such as mechanical means that detect the position of the springs on both sides of the weld seam, optical means that identify the weld seam in the material, etc.

(41) The mattress in accordance with the invention offers resilience properties equivalent to those achieved in conventional pocket-spring mattresses, providing the same firmness, comfort and so on. Possibly somewhat harder springs than normal may be used to increase the mattress firmness. Alternatively, the same effect can be achieved, however, in other ways, for example by means of springs that when being enclosed are subjected to a higher pre-loading tension.

(42) The invention has been described above with reference to one embodiment. However, several variants of the invention are possible many of which have already been discussed above. For example, other cover materials may be used as also differently sized springs, and so on. Such closely related variants should be considered to be within the scope of protection of the invention as defined in the appended claims.