Foam mattress core with integrally formed rails
A modified convolution process for foam mattresses creates integrally formed rails and customizable firmness zones using frusto-conical rollers and adjustable separation, addressing the limitations of existing designs by producing parallel side rails and varying firmness regions.
Patent Information
- Authority / Receiving Office
- US · United States
- Patent Type
- Applications(United States)
- Current Assignee / Owner
- Filing Date
- 2025-11-11
- Publication Date
- 2026-03-05
AI Technical Summary
Existing mattress designs, particularly those using convolution machines, fail to produce acceptable side rails in foam mattresses, often resulting in unsuitable or non-parallel top surfaces and ridges, and lack the ability to customize firmness regions effectively.
A modified convolution process using counter-rotating rollers with frusto-conical end pieces and adjustable roller separation, combined with a cutting blade, to create a single-piece foam mattress core with integrally formed rails and customizable firmness regions by varying pillar heights and patterns.
Produces a foam mattress core with constant-height, parallel side rails and customizable firmness zones, enhancing support and comfort by simulating coil springs with foam pillars, while maintaining structural integrity and avoiding sagging.
Smart Images
Figure US20260060442A1-D00000_ABST
Abstract
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of Patent Cooperation Treaty application PCT / US24 / 47040 filed September 17, 2024 and U.S. provisional application Serial No. 63 / 586,094 filed September 28, 2023, the disclosures of which are hereby incorporated in their entirety by reference herein.TECHNICAL FIELD
[0002] The present disclosure relates to a foam mattress. More particularly, the disclosure relates to a foam mattress having a core with a convoluted portion and integrally formed rails.BACKGROUND
[0003] Mattress design is a significant factor in sleep quality. A variety of different mattress structures are in use. In coil-type mattresses, metal springs support weight of the occupant while deflecting to conform to the occupant’s body shape. A layer between the springs and the occupant distributes the forces. Foam-type mattresses rely on the resilient properties of the foam material to support weight and conform to the occupant to a desired degree. Different degrees of stiffness may be desirable in different regions. For example, it may be desirable to have the sides be stiffer to better support a person sitting on the edge of a bed. In addition to material selection, mattress designers may include various patterns of bumps and recesses to customize the properties of a foam mattress.
[0004] The desired pattern of bumps and recesses may be formed using a convolution machine. A convolution machine includes two counter-rotating rollers having cooperating projections and recesses. A block of foam is passed between the counter-rotating rollers. The rollers compress the foam block to varying degrees in different areas and deflect some areas toward one of the rollers. A cutting blade located between the two rollers cuts the foam while it is in the compressed and deflected state. When the foam exits the machine and returns to its uncompressed density, the two pieces have varying thicknesses. In areas that were deflected toward the top roller, the top piece is thicker and the bottom piece is thinner. Conversely, in areas that were deflected toward the bottom roller, the top piece is thinner and the bottom piece is thicker. The two pieces are complimentary, with the thicknesses adding up to the thicknesses of the initial block of foam.
[0005] U.S. Patent 7,174,613 discloses use of a convolution machine to fabricate a foam core for a mattress. The convolution machine is used to create voids in the foam core into which coil springs or foam with different material properties is inserted. The cutting blade is positioned close to the top roller such that some portions of the foam are not cut and those portions of the bottom piece have the same thickness as the original block of foam. Instead of a contiguous top piece, a number of discrete pieces are removed from the top of the block of foam. In some embodiments, the outer three inches of the block of foam are not cut, resulting in a foam core with an integral head and foot rail that are the same thickness as the original block of foam. In some applications, these uncut portions may be unsuitable as side rails.
[0006] U.S. Patent Application Publication 2011 / 0145966 discloses a reversible foam mattress. The mattress is formed using a convolution machine that is narrower than the width of the original block of foam, leaving uncut side rails on either side of the convoluted portion. Both the top surface and the bottom surface of the core have convolutions, although the convolutions are different sizes. The side rails have flat top and bottom surfaces which may be substantially flush with the peak height of the convolutions on each side.SUMMARY
[0007] A mattress includes an integrally formed foam core and a foam top piece. The integrally formed foam core has a flat bottom, a convoluted central region having an array of pillars extending away from the flat bottom, and two edge regions. A thickness is substantially constant throughout the edge regions. The foam top piece extends over the integrally formed core across the edge regions and the central region. First and second rails may extend between ends of the edge regions. The convoluted central region may include a torso region between a head region and a foot region. A height of the pillars may be less in the torso region than in the head region and in the foot region. In one embodiment, the edge regions form side rails. The first and second rails may be adjacent to the head and foot regions respectively. In another embodiment, the edge regions form head and foot rails while the first and second rails are side rails. The pillars may extend farther from the flat bottom than the edge regions.
[0008] A single-piece foam mattress core includes a convoluted central region and first and second rails. The convoluted central region has an array of pillars that extend away from a flat bottom surface. The first rail, which is located on a first edge of the central region, has a flat first top surface inclined no more than 5 degrees relative to the bottom surface. The second rail, which is located on a second edge of the central region opposite the first edge, has a second flat top surface inclined no more than 5 degrees relative to the bottom surface. The first and second flat top surfaces may be inclined no more than 2 degrees relative to the bottom surface. The first and second rail are integrally formed with the central region. The pillars extend farther from the bottom surface than the first and second top surfaces extend from the bottom surface. The convoluted central region may include a head region, a foot region, and a torso region between the head region and the foot region, wherein a height of the pillars is less in the torso region than in the head region and in the foot region. In one embodiment, the first rail may be adjacent to a first side of the head region, a first side of the torso region, and a first side of the foot region. The second rail may be adjacent to a second side of the head region, a second side of the torso region, and a second side of the foot region. In another embodiment, the first rail maybe adjacent to the head region and opposite the foot region. The second rail may be adjacent to the foot region and opposite the head region.
[0009] A method of making a single-piece foam mattress core includes passing a block of foam between two rollers and cutting the block as it emerges from the rollers to separate the block into the foam mattress core and a scrap piece. The two rollers are supported to rotate in opposite directions about parallel axes. Each roller has a convolution section defining projections or recesses. At least one of the rollers has a first frusto-conical end section and may have a second frusto-conical end section opposite the first frusto-conical end section. A larger diameter end of the first frusto-conical end section maybe adjacent to the convolution section. An angle of a conical surface of the first frusto-conical end section relative to a centerline may be between 1 degree and 3 degrees. The foam mattress core has a flat bottom surface. A portion of the foam mattress core that passed between the convolution sections of the rollers has a convoluted top surface. A portion of the foam mattress core that passed by the first frusto-conical end section has a first flat top surface substantially parallel to the flat bottom surface. The scrap piece may have a width equal to a width of the foam mattress core. The projections or recesses may be arranged such that the convoluted top surface of the foam mattress core has an array of pillars. The pillars may extend farther from the bottom surface than the first flat top surface. The method may include changing a distance between the rollers to change a height of the pillars. The projections and recesses may be arranged such that the convoluted top surface of the foam mattress core has a head portion and a foot portion separated by a torso section. The top surface of the torso portion may be flat or may have shorter pillars than the foot portion and the head portion.BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a top view of a first foam mattress having a convoluted core region with foam pillars that simulate coil springs.
[0011] FIG. 2 is a partial exploded view of the mattress of FIG. 1.
[0012] FIG. 3 is a cross-sectional view of the integrated core of the mattress of FIG. 1.
[0013] FIG. 4 is a cross-sectional view of a convolution machine suitable for fabricating the integrated core of FIG. 3.
[0014] FIG. 5 is a pictorial view of the rollers of the convolution machine of FIG. 4.
[0015] FIG. 6 is a partial side view of the rollers of the convolution machine of FIG. 4.
[0016] FIG. 7 is a top view of a second foam mattress having a convoluted core region with foam pillars that simulate coil springs.
[0017] FIG. 8 is a cross-sectional view of the integrated core of the mattress of FIG. 7.DETAILED DESCRIPTION
[0018] As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention.
[0019] FIG. 1 is a top view of a foam mattress 10 according to a first embodiment. The foam mattress has a core region 12, two side rails 14, a head rail 16, and a foot rail 18. In the core region, an array of foam pillars 20 simulate coil springs. As shown in the partial exploded view of FIG. 2, the mattress 10 is formed from an integrated core piece 22, a foot rail 24, a head rail (not shown), and a top piece 26. The integrated core piece includes both the array of pillars 20 and side rails 14. The foot rail, head rail, and top piece may be separate pieces or may be integrally formed with one another.
[0020] FIG. 3 is a partial cross section of the integrated core piece 22. The integrated core piece 22 has a flat bottom surface 30. The side rails 14 have a flat top surface 32 which is substantially parallel to the bottom surface and offset by a distance A. More particularly, surface 32 should be inclined by no more than 5 degrees relative to surface 30 and preferably no more than 2 degrees. In an exemplary embodiment, dimension A is slightly less than 6 inches. The top surface of the side rails has a width B which, in the exemplary embodiment is approximately 4 inches. The peaks of the pillars extend a distance C from the bottom surface. To avoid an appearance of sagging, it is important for the pillars to extend at least as high, and preferably slightly higher, than the side rails. A base of the pillars is a distance D from the flat bottom surface. In the exemplary embodiment, D is approximately 2.75 inches. The pillars are frusto-conical with flat, circular top surfaces having a diameter of E, which in the exemplary embodiment is approximately 2.75 inches.
[0021] The inventors have discovered that the methods described in the prior art do not produce acceptable side rails 14 for the integrated core piece 22 as illustrated in FIG. 3. If the cutting blade is adjusted such that no material is removed at the side rails, then the side rail height A will be at least equal to the height C of the pillars. The inventors have discovered that using convolution rollers narrower than the original foam block produced side rails in which the top surface 32 is not substantially parallel to the flat bottom surface 30. In particular, a ridge is formed in the side rail with inclined portions on either side of the ridge.
[0022] The inventors have developed a modified convolution process for producing the integrated core piece 22 of FIG. 3. The tooling for this process is illustrated in FIGS. 4-6. FIG. 4 is a side view of a convolution machine 40. A block of foam 42 is pushed along a feed table 44 between two counter-rotating rollers 46 and 48. A pattern of projections and recesses on the two rollers compress the foam and translate the foam vertically to different extents in different areas. As the foam emerges from the rollers, it is cut by a cutting blade 52. The cutting blade may be a band saw blade, an oscillating blade, a heated wire, or other mechanism that cuts foam. The blade cuts the block of foam into two pieces - integrated core piece 22 and a single scrap piece. The two pieces have complimentary thicknesses which add to the thickness of the foam block 42. Each of the two pieces have the same width (defined as parallel to the axis of the rollers) and the same length (defined as perpendicular to the axis of the rollers) as the foam block. The scrap piece has a top surface that is contiguous and uninterrupted because the cutting blade extends beyond the edges of the foam block during the process.
[0023] FIG. 5 is a pictorial view of the rollers. Tapered end pieces 54 and 56 are appended to the end of one of the rollers. The tapered end pieces are frusto-conical. A diameter of the tapered end piece adjacent to the roller is greater than a diameter of the tapered end piece on the outside. The portions of foam block 42 that pass under the frusto-conical end pieces 54 and 56 become the side rails of the integrated core piece 22. As shown in FIG. 6, the conical surfaces are inclined at an angle α with respect to the centerline. The inventors have discovered that α should be approximately 2 degrees to achieve a constant-height rail as depicted in FIG. 3. Use of a tapered roller to produce a constant-height rail was a surprising, unexpected result. An axial length of each of the tapered end pieces is at least equal to the dimension B.
[0024] The inventors have further discovered that, by moving bottom roller 48 vertically with respect to roller 46 and blade 52, dimension D in FIG. 3 can be adjusted without appreciably changing dimensions A, B, C, and E. Increasing dimension D makes the pillars 20 shorter which makes the mattress firmer. This permits fabrication of mattresses with different degrees of firmness without changing the tooling. Furthermore, adjusting the separation between the rollers while foam block 42 is being drawn through the machine produces a mattress core with different firmness regions. More particularly, a mattress core is produced with a central firmer region to support a user’s torso and softer, more compliant regions for the user’s head and feet. Specifically, the rollers are moved apart from one another when the block of foam is approximately one third of the way through and then moved back to the original distance when the block of foam is approximately two thirds of the way through.
[0025] FIG. 7 is a top view of a foam mattress 10ʹ according to a second embodiment. The foam mattress has a core region 12ʹ, two side rails 14ʹ, a head rail 16ʹ, and a foot rail 18ʹ. In the core region, an array of foam pillars 20 simulate coil springs. The core region includes a central firmer torso region and softer, more compliant foot and head regions. The torso region may have no pillars as illustrated or may have pillars with different dimensions than the pillars in the head and foot regions. An integrally formed core piece includes the core region 12ʹ, the head rail 16ʹ, and the foot rail 18ʹ. The side rails 14ʹ and the top piece may be separate pieces or may be integrally formed with one another.
[0026] FIG. 8 is a partial cross section of the integrated core piece 22ʹ. The integrated core piece 22ʹ has a flat bottom surface 30. The head rail 16ʹ and the foot rail 18ʹ (not shown in FIG. 8) have a flat top surface 32 which is substantially parallel to the bottom surface and offset by a distance A. More particularly, surface 32 should be inclined by no more than 5 degrees relative to surface 30 and preferably no more than 2 degrees. In an exemplary embodiment, dimension A is slightly less than 6 inches. The top surface of the head and foot rails has a width B which, in the exemplary embodiment is approximately 4 inches. The peaks of the pillars extend a distance C from the bottom surface. To avoid an appearance of sagging, it is important for the pillars to extend at least as high, and preferably slightly higher, than the side rails. The pillars are frusto-conical with flat, circular top surfaces having a diameter of E, which in the exemplary embodiment is approximately 2.75 inches. In the head and foot regions, the pillars are full height. In the central torso region, the pillars may be absent as shown or may be significantly shorter. There may be transition regions between the torso region and the head and foot regions in which the dimensions of the pillars gradually change.
[0027] The integrated core piece 22ʹ, like the integrated core 22 of FIGS. 1-3, is formed using the process illustrated in FIGS. 4-6. The rollers include tapered end pieces 54 and 56. However, instead of varying the distance between the rollers to form the various regions of the core, the pattern of projections and recesses on the two rollers is varied. The portions of foam block 42 that pass under the frusto-conical end pieces 54 and 56 become the head and foot rails of the integrated core piece 22ʹ.
[0028] While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. Additionally, the features of various implementing embodiments may be combined to form further embodiments of the invention.
Claims
1. A mattress comprising: an integrally formed foam core having a flat bottom, a convoluted central region having an array of pillars extending away from the flat bottom, and two edge regions wherein a thickness is substantially equal throughout the edge regions; and a foam top piece extending over the integrally formed core across the edge regions and the central region.
2. The mattress of claim 1 further comprising: a first rail extending between first ends of the edge regions; and a second rail extending between second ends of the edge regions.
3. The mattress of claim 2 wherein: the convoluted central region comprises a torso region between a head region and a foot region; and a height of the pillars is less in the torso region than in the head region and in the foot region.
4. The mattress of claim 3 wherein: the edge regions form side rails; the foot region is adjacent to the first rail; and the head region is adjacent to the second rail.
5. The mattress of claim 3 wherein: the first and second rails are side rails; the edge region adjacent to the foot region forms a head rail; and the edge region adjacent to the head region is adjacent to the second rail.
6. The mattress of claim 1 wherein the edge regions extend no farther from the flat bottom than the pillars.
7. The mattress of claim 1 wherein the pillars extend farther from the flat bottom than the edge regions.
8. A single-piece foam mattress core comprising: a convoluted central region having an array of pillars that extend away from a flat bottom surface; a first rail on a first edge of the central region, the first rail having a flat first top surface inclined no more than 5 degrees relative to the bottom surface; and a second rail on a second edge of the central region opposite the first edge, the second rail having a second flat top surface inclined no more than 5 degrees relative to the bottom surface; wherein the first and second rail is integrally formed with the central region; and the pillars extend farther from the bottom surface than the first and second top surfaces extend from the bottom surface.
9. The single-piece foam mattress core of claim 8 wherein the first and second flat top surfaces are inclined no more than 2 degrees relative to the bottom surface.
10. The single-piece foam mattress core of claim 8 wherein the convoluted central region comprises a head region, a foot region, and a torso region between the head region and the foot region, wherein a height of the pillars is less in the torso region than in the head region and in the foot region.
11. The single-piece foam mattress core of claim 10 wherein: the first rail is adjacent to a first side of the head region, a first side of the torso region, and a first side of the foot region; and the second rail is adjacent to a second side of the head region, a second side of the torso region, and a second side of the foot region.
12. The single-piece foam mattress core of claim 10 wherein: the first rail is adjacent to the head region and opposite the foot region; the second rail is adjacent to the foot region and opposite the head region; andneither of the first and second rail is adjacent to the torso region.
13. A method of making a single-piece foam mattress core, the method comprising: providing two rollers, the rollers supported to rotate in opposite directions about parallel axes, each roller having a convolution section defining projections or recesses, and at least one of the rollers having a first frusto-conical end section; passing a block of foam between the rollers; and cutting the block as it emerges from the rollers to separate the block into the foam mattress core and a scrap piece; wherein the foam mattress core has a flat bottom surface; a portion of the foam mattress core that passed between the convolution sections of the rollers has a convoluted top surface; and a portion of the foam mattress core that passed by the first frusto-conical end section has a first flat top surface substantially parallel to the flat bottom surface.
14. The method of claim 13 wherein the scrap piece has a width equal to a width of the foam mattress core.
15. The method of claim 13 wherein the projections or recesses are arranged such that the convoluted top surface of the foam mattress core has an array of pillars.
16. The method of claim 15 wherein the pillars extend farther from the bottom surface than the first flat top surface.
17. The method of claim 13 wherein: a larger diameter end of the first frusto-conical end section is adjacent to the convolution section; and an angle of a conical surface of the first frusto-conical end section relative to a centerline is between 1 degree and 3 degrees.
18. The method of claim 15 further comprising changing a distance between the rollers to change a height of the pillars.
19. The method of claim 13 wherein: the at least one roller having the first frusto-conical end section also has a second frusto-conical end section on an opposite side of the convolution section from the first frusto-conical end section; and a portion of the foam mattress core that passed by the second frusto-conical end section has a second flat top surface substantially parallel to the flat bottom surface.
20. The method of claim 19 wherein: the projections or recesses are arranged such that the convoluted top surface of the foam mattress core has a head portion and a foot portion separated by a torso section;the top surface of the head portion and the foot portion has an array of pillars which extend farther from the bottom surface than the first and second flat top surfaces; andthe top surface of the torso portion is either flat or has shorter pillars than the foot portion and the head portion.