Foam mattress core with integrally formed rails

Abstract

A foam mattress utilizes an integrally formed core that includes both a convoluted central section and side rails. The central section includes foam pillars that simulate coil springs. The integrally formed core is formed using a convolution machine. To ensure that the top surfaces of the integrally formed rails are flat and parallel to the bottom surface, one of the rollers of the convolution machine is provided with frusto-conical end sections.

What is claimed is: 
     
         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; and 
 neither 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; and 
 the top surface of the torso portion is either flat or has shorter pillars than the foot portion and the head portion.