HONEYCOMB MATTRESS SUPPORT
FIELD OF THE INVENTION
This invention relates generally to bedding systems, and more particularly to an apparatus and method using honeycomb technology to make a mattress and/or support for a mattress or other padding forming a sleeping surface.
BACKGROUND OF THE INVENTION
A typical bed includes a mattress supported by a bed frame. Often, a box spring is positioned between the mattress and the bed frame to provide additional support for the user. A typical mattress is formed from coiled springs and padding encased in a fabric covering, although other types of mattresses are available, including mattresses made from man made foam or from natural fibers, such as cotton or wool. Alternatively, a mattress or mattress overlay can be formed from a honeycomb material; for example, as described in U.S. Patent No. 5,701,621, entitled "Liner for Overlaying a Mattress", issued to Landi, et al, on December 30, 1997. A box spring is usually formed from coiled springs and a wooden frame encased by a fabric covering.
SUMMARY OF THE INVENTION
Briefly, the present invention relates to the provision of a two component mattress system preferably including a mattress positioned on top of a mattress support, although either component can be provided separately. The mattress and/or mattress support includes a core formed of undulated strips of resilient thermoplastic material, thermal compression bonded together and expanded to form a honeycomb shaped core structure having cell walls defining a plurality of contiguous regularly shaped cells. The structures have a top face and a bottom face, each of which is subjected to a thermal compression planarizing deformation to stabilize the expanded cores. A first facing sheet of resilient thermoplastic material may be bonded to the top face of the honeycomb core, and a second facing sheet of resilient thermoplastic material may be bonded to the bottom face of the honeycomb core. The mattress is configured to provide comfortable support to a reclining human body. The mattress support is configured to support the mattress and a human body positioned on top of the mattress.
Embodiments can include one or more of the following features: The mattress support can be at least approximately 5 feet in length and at least approximately 3 feet in width. The
honeycomb core can be at least approximately 4 inches in thickness between the top face and the bottom face. The honeycomb core can be formed from a thermoplastic polyurethane material having a durometer of approximately Shore A 80-85. The first facing sheet can be formed from a 20 gauge thermoplastic polyurethane elastomer material that is approximately 0.015 to 0.025 inches in thickness. The mattress support can be formed from two or more honeycomb panels placed side-by-side or fused together. The facing sheets and/or the panel can be formed from impervious or perforated material.
The mattress can also be formed from a honeycomb core formed of undulated strips of resilient thermoplastic material, thermal compression bonded together and expanded to form cell walls defining a plurality of contiguous regularly shaped cells. The honeycomb core has a top face and a bottom face at least one of which has been subjected to a thermal compression planarizing deformation to stabilize the expanded core. A first facing sheet of resilient thermoplastic material maybe bonded to the top face, and a second facing sheet of resilient thermoplastic material may be bonded to the bottom face. The mattress can likewise be formed as a unitary body or be divided into two or more separate components that can be suitably positioned together.
Implementations of the invention can realize one or more of the following advantages. The honeycomb mattress support is lighter in weight than a conventional box spring. The honeycomb panel used to form the honeycomb mattress support resists permanent deformation. Different materials can be used to make the honeycomb panel to vary the properties, e.g., firmness, weight.
The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.
BRIEF DESCRIPTION OF THE DRAWING FIGURES
FIG. 1 is a schematic representation of a user lying on a mattress system in accordance with the present invention;
FIG. 2 is a partially broken schematic representation of a portion of a honeycomb panel in accordance with the present invention;
FIGS. 3-6 are cross-sectional views schematically illustrating a process for fabricating the honeycomb panel of FIG. 2;
FIG. 7 is an exploded perspective view schematically illustrating a step in the making of a honeycomb panel in accordance with the present invention; FIG. 8 is a perspective view schematically depicting a honeycomb panel attached to a spreader plate;
FIGS. 9a-9f are schematic representations of cells of a honeycomb panel;
FIGS. 10-12 are cross-sectional views illustrating a process for bonding facing sheets to a honeycomb core in accordance with the present invention; FIGS. 13A-B are schematic top views of a mattress support formed from two honeycomb panels; and
FIGS. 14A-F are sides views illustrating processes for seaming a side of a honeycomb panel in accordance with the present invention.
Like reference symbols in the various drawings indicate like elements.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to FIG. 1 of the drawing, a honeycomb mattress system is shown at 1 providing a sleeping surface 2 for a user 3. The honeycomb mattress system 1 includes a mattress 4 positioned on top of a mattress support 5. Optionally, the mattress support 5 can be supported by a frame 6. The mattress support 5 is made from a honeycomb core material and replaces a box spring used in a typical bed having a mattress and box spring configuration. That is, the mattress support 5 provides additional support beneath the mattress 4, to further support the user 3 while lying prostrate on the sleeping surface 2.
In FIG. 2, an embodiment of a honeycomb core 10 used to form the mattress support 5 is shown. The expanded honeycomb core 10 is made of serpentine strips 12 of plastic material that, as will be described below, are bonded together at spaced intervals. Facing sheets 14 and 16 can be thermal compression bonded to the honeycomb core 10. Alternatively, one of the facing sheets 14 or 16 can be eliminated. The expanded honeycomb core 10 is an anisotropic three- dimensional structure having predetermined degrees of flex along the x, y, and z axes. Each cell
of the core is formed in part by wall segments formed by portions of the serpentine strips shared with adjacent cells. In addition, each cell shares a pair of double thickness wall segments with two adjacent cells. Each cell can be a hermetically sealed chamber or be ventilated as will be described below. The mattress support 5 has high tear and tensile strength and is highly resilient, with optimal compression load and shock absorption or dispersion characteristics, yet can be relatively lightweight. Selected combinations of elastomeric material, honeycomb cell configuration, core thickness and facing material variables can determine the characteristics of softness or hardness, resilient recovery rate and rigidity or flex. The facing materials can be selected from a wide variety of solid or perforated films, including thermoplastic urethanes, foams, EVA elastomer impregnated fibers and fabrics.
FIGS. 3 through 12 illustrate an exemplary method of fabrication of the cores for the mattress and support components, although other techniques can be used. The first step in the sequence is to prepare the multiple sheets of plastic material from which the honeycomb core 10 is to be fabricated, hi one embodiment, the sheets are made of 0.015 inch thick thermoplastic polyurethane elastomer of 85 durometer that is cut into 17 inch by 58 inch rectangular pieces. As depicted in FIG. 3, the first sheet 20 is laid out upon the upper surface of a bonding fixture base 22 which can have a closed cell foam pad 23 disposed on its upper surface. A Teflon® coated fiberglass fabric spacer in the general shape of a comb having a plurality of teeth or fingers 24 is then placed over the sheet 20, and a second sheet 26 is placed over the comb fingers 24.
As depicted in FIG. 4. a Teflon impregnated fiberglass fabric sheet 28 is then placed over sheet 26, and the base 22 is moved into position beneath a thermal bonding plate 30 having horizontally extending bonding ribs 32. Note that the lateral center-to-center spacing between the elongated ribs 32, the lengths of which extend into the plane of the drawing, is substantially the same as the center-to-center spacing between the fingers 24 of the Teflon spacer comb. The fingers 24 are positioned laterally offset so as to be centered between the ribs 32 and are thus intended to limit the bonding between strips to the areas directly beneath the ribs 32. The depth of the ribs 32 is selected so that little if any heat is transferred from the recessed surfaces 33 to sheet 26. As suggested by the arrow 34, once the parts are in position, the base 22 is moved upwardly to cause the top surface of the Teflon sheet 28 to engage ribs 32 and force the areas of
the bottom surface of sheet 26 lying beneath the ribs 32 into compressive engagement with corresponding top surface areas of sheet 20.. The plate 30 is elevated to a temperature of approximately 460 degrees Fahrenheit so that heat will be transmitted from the ribs 30 and through sheet 28 to sheets 26 and 20, and cause the contacting areas of sheets 20 and 26 to be thermal compression bonded together. The base travel (and thus the compression force), the temperature of plate 30, and the dwell time of each bonding cycle are carefully selected and controlled to achieve a desired bond quality. As suggested above, the function of the Teflon comb fingers 24 is to maintain separation between sheets 20 and 26 in the unbonded sheet surface areas between the bonded surface areas. The base 22 is then lowered, the Teflon sheet 28 is lifted and, as depicted in FIG. 5, a second comb shaped separator having fingers 36 is laid upon the upper surface of sheet 26, laterally offset relative to the first comb 24 so that the second comb's fingers 36 lie directly over the previously bonded areas of the sheets. A third sheet 38 of plastic material is then placed over the comb fingers 36, and the protective Teflon sheet 28 is replaced over the top of sheet 38. The base 22 is thereafter shifted rightwardly, as indicated by arrow 40, a predetermined distance so that the areas of sheet 38 to be bonded to sheet 26 lie directly beneath ribs 32.
As depicted in FIG. 6, the base 22 is then again moved upwardly to engage ribs 22 with sheet 28 and effect bonding between sheets 26 and 38. Note that the ribs 32 are now aligned directly over the comb fingers 24 and sandwich the rows of surface areas 37 of sheets 26 and 38 therebetween, causing such areas to be thermally bonded to each other.
Although not depicted in detail, base 22 is then again lowered, the comb 24 is removed from between sheets 20 and 26, and after removal of sheet 28, is laid upon the upper surface of sheet 38. A fourth plastic sheet is subsequently laid thereupon along with the protective sheet 28, the base 22 is shifted leftwardly, and the assembly is again moved upwardly into contact with ribs 22 to complete the third bonding operation. The above-described process is successively repeated until a laminated assembly having a pre-selected number of laminations, such as is graphically represented in FIG. 7, is provided. In one implementation, the laminated block 50 includes 110 sheets of material bonded together along the bond row surface areas 52.
The laminated block 50 can then be cut into multiple core strips. As depicted in FIG. 7, the strip cutting operation can be carried out by a commercially available wateijet cutting machine, the jet nozzle 54 of which is caused to traverse along a line transverse to and in a plane
normal to the lengths of the bonded row areas 52 so that its jet 56 causes a core strip 58 to be severed from the block 50. In another implementation, the longitudinal cuts are made with a guillotine cutter. Alternatively, a shearing device or any other suitable means of cutting the block 50 into core strips can be used. In one embodiment, to create a honeycomb core 10 for use in a mattress support, a core strip 58 approximately 4.25 inches is severed from the block 50. The core strip 58 is then expanded into a honeycomb configuration. This may be accomplished either manually, or mechanically by suitable mechanisms. In one implementation, the core expansion operation is accomplished using a metal spreader plate such as that depicted at 60 in FIG. 8. The plate 60 has predetermined width W and length L and includes along each length extending side a row of vertically projecting pins 61 and 62 (e.g., polyvinyl chloride pins) disposed at regular intervals corresponding to the desired "pitch" of the core to be developed. For example, when expanded and before trimming, the resulting honeycomb configured core is approximately 40 inches by 86 inches. The "L direction" shown in FIGS. 2 and 8 is the direction including the double-thickness walls. Preferably, the L direction coincides with the length of the core, although the opposite orientation (i.e., the L direction coinciding with the width) can be used.
The core strip 58 is expanded by application of separating forces in the directions illustrated by the arrows E in FIG. 7. In one implementation, the outermost row of cells on the upper side 63 are hooked over pins 61 of plate 60, while the cells on the lower side 64 are hooked over pins 62 as shown in FIG. 8. The spacing between pins in the L direction and the spacing between the rows of pins in the W direction are carefully selected in conjunction with the bond row width (as determined by the width of bonding plate ribs 32) and separation between bonds (as determined by the spacing between ribs 32) such that, when the core strip is expanded and hooked over the pins 61 and 62, a particular cell configuration will be defined. Note for example that for a particular combination of a selected number of core sheets, bond width and bond spacing, a particular pin spacing in the L direction and a particular pin row spacing in the W direction might yield a cell configuration such as that illustrated in FIG. 9a wherein the cell dimension dl in the core expansion direction is greater than the cell dimension d2 in the core strip length direction. On the other hand, by increasing the spacing (in the direction) between pins in each row and decreasing the spacing (in the W direction) between pin rows, the same core when expanded will have cells with different cell dimensions d3 and d4, as depicted in FIG. 9b. Moreover, as
illustrated in FIG. 9c, by changing the bond row width B and the separation between bond rows, a still different cell configuration can be achieved. FIG. 9d shows yet another alternative implementation, wherein by appropriate selection of the cell dimension parameters the cell is configured in an approximate hexagonal shape. Other configurations are also possible. Thus, by judicious selection of core bond width, core bond spacing, spreader plate pin separation (in both L and W directions) and the type of materials used for the core one can provide a honeycombed core structure having particular desired characteristics.
In one example, the dimensions of the cells in the mattress support 5 might be as follows: referring to FIG. 9a, each cell is made approximately 1.5 inches long in the dl direction and approximately 1.25 inches wide in the d2 direction. Dimensions of the core cells can be varied by changing the dimensions and/or spacings of the bonding ribs used during the build up of the core stack.
The expansion operation can be done manually as described above, or a suitable honeycomb expander mechanism can be used to expand the core strip 58. For example, the expander mechanism described in U.S. Patent No. 5,375,305 issued to Stillman on December 27, 1994, the entire contents of which are hereby incorporated by reference, can be used to expand the core strip 58. Other mechanisms or techniques can likewise be used.
Referring back to FIG. 8, it will be appreciated that the expanded core can be positioned upon plate 60 and an inspection made to assure that the rows of cells are properly aligned and oriented. At this point, the core is ready for planarization prior to receiving the facing sheets 14 and 16.
Moving ahead now to FIG. 10, the planarization operation will be described. As illustrated, the spreader plate 60 and attached core 58 are placed on a lifting bed 69 beneath a press plate 70 having a smooth lower surface which is aligned parallel to plate 60, and a 10 mil Teflon sheet 72 is placed over the core 58.
The bed 69 is then raised causing core 58 and sheet 72 to be moved upwardly into engagement with plate 70 to effect one or more searing operations which have the effect of planarizing the upper surface of core 58 by deforming the upper extremities of the core walls as indicated at 74. Again, the bed travel, press plate temperature and press dwell time are carefully selected and controlled to achieve the desired result. In one implementation, the press plate
are aligned with the length L (i.e., the longer dimension), to provide additional support to the structure, although other orientations can be used. With the top and bottom edges of these walls bonded to the upper and lower facing sheets 14 and 16 a unitary honeycomb panel is provided with no seams or separations. Because of the high integrity of the bonds between the core and facing sheets, the anisotropic features of the structure are uniform and predictable.
In an alternative embodiment, perforations may be formed in one or both of the facing sheets to unseal the honeycomb cells. Alternatively, or additionally, the cell walls can include perforations as shown in FIGS. 9e and 9f. Specifically, in FIG. 9e, a cell 110 is shown with perforations 112 in the side walls 110, while in FIG. 9f , a top view of a facing sheet 114 is shown with perforations 116 in the facing walls overlying a cell 118. In this case, before starting the process of forming the honeycomb cells as described above, the plastic sheets to be used as core strips and/or facing sheets are perforated, such that a matrix of small holes exist throughout. Perforating the honeycomb core walls and/or the facing sheets reduces the weight of the resulting mattress or support, since the overall quantity of material used is reduced, and increases the resiliency and flexibility. The flexibility is increased because there is less material to constrain each segment of the material against bending or perhaps stretching. The resiliency, or ability of the structure to spring back to its original form after being compressed, is also enhanced by virtue of the additional passages through which air can return to fill the cells. The perforations can also provide improved air circulation. The mattress support 5 can be formed in various sizes to accommodate mattresses of various sizes. For example, the mattress support 5 can have dimensions of approximately 74 inches by 36 inches to accommodate a twin size mattress; 80 inches by 30 inches to accommodate a queen size mattress; or 84 inches by 36 inches to accommodate a king size mattress. With respect to the queen and king size embodiments, two twin size mattress supports can be positioned side-by-side lengthwise to support a corresponding king or queen size mattress. In one embodiment, wherein the mattress support is to be approximately 4 inches thick, a honeycomb core having a pre-planarization thickness of 4.25 inches can be used. The overall thickness is reduced by approximately 1/8 of an inch on each face of the core during the planarization process. The mattress support can be sized after the core is fabricated as described above, i.e., trimmed down to the desired dimensions, or the core can initially be formed according to the desired dimensions.
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Referring to FIGS. 13 A and 13B, in one implementation, a mattress support 100 can be formed by fusing together two or more honeycomb cores 102, 104 (e.g., for a queen or king size mattress support), before or after applying the facing sheets. This can facilitate fabrication, because smaller core panels can be created. Additionally, if a defect is found in a panel rendering it unusable because the panel is smaller than if a single panel were being used, less material is wasted. One technique for fusing the panels together is radio frequency sealing, although other techniques can be used (e.g., using an adhesive, heat fusing a strip of facing material down the seam, etc.). For example, the sides to be joined can be pressed against each other and heat sealed at a temperature of approximately 400 degrees Fahrenheit. Once assembled, the once multipiece honeycomb core undergoes planarization to prepare the upper and lower faces for facing sheets. Alternatively, the honeycomb core panels 102, 104 can be planarize separately before they are fused to one another. In yet another alternative, the honeycomb core panels 102, 104 can be planarized and faced separately before being fused together. In another embodiment wherein the mattress support is formed from a honeycomb core and facing sheets as described above, and the four sides of the mattress supports are not faced, the cell structure is visible, the support structure can be encased, for example, in a fabric encasement. Alternatively, if the sides are unfaced, a band of material similar to the facing material can be bonded to the perimeter of the core. Referring again to FIGS. 2, 13A and 13B, although the cells are shown as substantially rectangular in shape, as discussed above in reference to FIGS. 9a-d, other configurations are possible. For example, the cells can be configured to be substantially hexagonal in shape. Additionally, as also discussed above, the honeycomb core can be oriented such that the L direction (direction parallel to the double-thickness walls) is lengthwise, widthwise or otherwise oriented with respect to the mattress support.
In another embodiment, a seam can be formed along the sides of the mattress support by bonding together opposing top and bottom edges. An exemplary process for forming the seams in a mattress support 200 is shown in FIGS. 14A-C wherein slits 202 are cut on both the upper and lower faces of the mattress support along the length of the side 204 that is to be seamed. The slits 202 extend through the upper and lower facing sheets 206, 208 and partially into the walls of the cells. The slits 202 allow the upper and lower edges 210, 212 to be pulled
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toward each other. As shown in FIG. 14B, the lower edge 212 is positioned on abase 214 of a radio frequency sealing apparatus shown generally at 217, and including a radio frequency sealing bar 216. The bar is pressed downwardly onto, and compresses, the edges 210, 212. Radio frequency energy is transmitted through the sealing bar 216 causing the edges 210, 212 to fuse to one another. Optionally, a non- stick material, such as a Teflon® sheet, can be placed between the r sealing bar 216 and the edge 210 during the fusion process to avoid sticking to the bar.
As shown in FIG. 14C, once the radio frequency sealing operation is complete, a melt sealed flange 218 is created that bonds the two edges 210, 212. The flange 218 is similar to a seam allowance created when sewing two pieces of fabric together using a sewing machine. The flange 218 can be trimmed back as much as possible, while maintaining the bond between the edges 210, 212. Optionally, an edge trim can be applied to the flange 218; for example, a fabric trim can be undertaken to provide a more appealing, finished look. Other joining techniques can also be used; for example, a heat joining technique, or other convenient methods to create the seam as described.
An alternative exemplary process for forming the seams in a mattress support 300 is shown in FIGS. 14D-F. The process is similar to what was described above in reference to FIGS. 14A-C, except that in this case slit 302 (or slits) made in the mattress support 300 are made approximately horizontally along the side 304 to be flanged. The opposing edges 306 and 308 are then pulled toward one another, and positioned on a base 310 of a radio frequency sealing apparatus. As shown, a sheet of non-stick material, such as a Teflon sheet 312 can be placed between the sealing bar 314 and the edge 306. The sealing bar 314 is pressed downwardly onto, and compresses, the edges 306, 308. Radio frequency energy is transmitted through the sealing bar 314 causing the edges 306, 308 to fuse to one another. Other techniques for creating a seamed edge can also be used; for example, it is not necessary to make a slit or slits in the material before fusing. However, by using the slits a better edge can be obtained. As suggested above, facing sheets can be applied to the four sides of the mattress support, in addition to the upper and lower faces as described above. In one implementation, facing sheets can be applied to the sides by fusion using a hot iron. Referring again to FIG. 1, the honeycomb mattress system+ includes a mattress 4 positioned on top of a mattress support 5. The mattress 4 can be formed from any kind of material, including coiled springs, cotton, wool, foam or a honeycomb panel. In one
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embodiment, the mattress 4 is made from a honeycomb core that is similar to the honeycomb core used to form the mattress support 5. The honeycomb core used for the mattress 4 can be made from a 5 mil thermoplastic polyurethane elastomer having a 70-75A durometer. The cells can be approximately 0.375 inches in width and length. The mattress 4 optionally can be faced with facing sheets made from a 0.020 gauge thermoplastic polyurethane elastomer having a 85 durometer. The mattress 4 can be bonded to the mattress support 5, for example, by heating the two surfaces separately and then thermal compression bonding them together.
The mattress support 5 can optionally be positioned on top of a frame 6, as depicted in FIG. 1, although the frame 6 is not necessary. The frame 6 can be made from any suitable material, including metal, wood and/or plastic.
A number of embodiments of the invention have been described above. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the following claims.
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