Formed core sandwich structure and method and system for making same

Abstract

A method and apparatus for producing a metal core sandwich structure that is lightweight and many times stiffer than regular sheet metal, and which is easily formable into curved structures as well as structures having compound curves. In one embodiment, a formed metal core includes a plurality of cells comprising alternating front and rear projections extending outwardly in front of and behind a median plane, with each projection having a bonding surface area or land configured to be brazed or bonded with corresponding external metal sheets on both sides of the formed metal core. A plurality of micro-abrasions or indentations are formed on the bonding lands, allowing stronger brazing or bonding joints to be formed between the metal core and the external metal sheets by facilitating improved capillary action by the metal core during the brazing or bonding process.

1 . A method of manufacturing a metal core sandwich structure, comprising: 
 forming a first metal core having a plurality of inwardly and outwardly projecting bonding lands;    forming a second metal core having a plurality of inwardly and outwardly projecting bonding lands;    forming micro-abrasions on a plurality of the bonding lands of each metal core;    placing the inwardly projecting bonding lands of the first metal core in contact with the inwardly projecting bonding lands of the second metal core;    placing a first metal sheet in contact with the outwardly projecting bonding lands of the first metal core and placing a second metal sheet in contact with the outwardly projecting bonding lands of the second metal core, thereby forming a sandwich structure; and    heating the sandwich structure to braze the first metal core, the first metal sheet, the second metal core and the second metal sheet together, wherein the micro-abrasions allow for improved capillary action at the bonding lands.    
   
   
       2 . The method of  claim 1 , further comprising forming a bulge on each inwardly projecting land of the first metal core and forming a dimple on each inwardly projecting land of the second metal core, wherein the bulges are configured to be received at least partially within corresponding dimples when the first and second metal cores contact each other.  
   
   
       3 . The method of  claim 1  wherein the first and second metal cores are formed with a press.  
   
   
       4 . The method of  claim 1  wherein first metal sheet and the second metal sheet comprise a plurality of cells, each of the cells having a pyramid-like shape.  
   
   
       5 . The method of  claim 1  wherein the micro-abrasions comprise grooves that are approximately 0.0005 to 0.002 inches in depth.  
   
   
       6 . The method of  claim 1  wherein the micro-abrasions cover approximately 50-80% of the surface area of the bonding lands.  
   
   
       7 . The method of  claim 1  wherein the micro-abrasions are formed on the bonding lands during the forming of the first metal core and second metal core.  
   
   
       8 . The structure of  claim 1  further comprising tack welding the first metal core, the second metal core, the first metal sheet and the second metal sheet together.  
   
   
       9 . A metal core sandwich structure comprising: 
 first and second metal cores each having a plurality of inwardly and outwardly projecting bonding lands, a plurality of the inwardly projecting lands of the first metal core brazed to a plurality of the inwardly projecting lands of the second metal core; and    a first metal sheet brazed to a plurality of the outwardly projecting bonding lands of the first metal core and a second metal sheet brazed to a plurality of the outwardly projecting lands of the second metal core, wherein a plurality of micro-abrasions are formed on the plurality of bonding lands prior to brazing so as to allow for improved capillary action at the bonding lands.    
   
   
       10 . The structure of  claim 9  further comprising a bulge on each inwardly projecting land of the first metal core and a dimple on each inwardly projecting land of the second metal core, wherein the bulges are received at least partially within corresponding dimples.  
   
   
       11 . The structure of  claim 9  wherein the first metal core is tack welded to the second metal core and the first metal sheet, and the second metal core is tack welded to the second metal sheet.  
   
   
       12 . The structure of  claim 9  wherein the first and second metal cores each have a generally sinusoidal cross-sectional shape.  
   
   
       13 . The structure of  claim 9  wherein the first and second metal cores each comprise a plurality of pyramid-like shaped cells.  
   
   
       14 . The structure of  claim 9  wherein the micro-abrasions comprise grooves that are approximately 0.0005 to 0.002 inches in depth.  
   
   
       15 . The structure of  claim 9  wherein the micro-abrasions cover approximately 50-80% of the surface area of the bonding lands.  
   
   
       16 . The structure of  claim 9  wherein the micro-abrasions are formed on the bonding lands during forming of the respective first and second metal cores.  
   
   
       17 . A metal core sandwich structure comprising: 
 first and second metal cores each having a plurality of inwardly and outwardly projecting bonding lands;    a first metal sheet brazed to a plurality of the outwardly projecting bonding lands of the first metal core;    a second metal sheet brazed to a plurality of the outwardly projecting lands of the second metal core; and    a third metal sheet brazed, on one side, to a plurality of the inwardly projecting lands of the first metal core and, on the other side, brazed to a plurality of the inwardly projecting lands of the second metal core,    wherein a plurality of micro-abrasions are formed on a plurality of the bonding lands prior to brazing so as to allow for improved capillary action at the bonding lands.    
   
   
       18 . The structure of  claim 17  further comprising a bulge on each inwardly projecting land of the first metal core and a dimple on each inwardly projecting land of the second metal core, wherein the bulges are received at least partially within corresponding dimples.  
   
   
       19 . The structure of  claim 18  wherein the third metal sheet comprises a plurality of bulges, at least some of the bulges of the third metal sheet receiving one of the corresponding bulges of the first metal core and positioned in one of the corresponding dimples of the second metal core.  
   
   
       20 . The structure of  claim 17  wherein the first and second metal cores each have a generally sinusoidal cross-sectional shape.  
   
   
       21 . The structure of  claim 17  wherein the first and second metal cores each comprise a plurality of pyramid-like shaped cells.  
   
   
       22 . The structure of  claim 17  wherein the micro-abrasions comprise grooves that are approximately 0.0005 to 0.002 inches in depth.  
   
   
       23 . The structure of  claim 17  wherein the micro-abrasions cover approximately 50-80% of the surface area of the bonding lands.  
   
   
       24 . The structure of  claim 17  wherein the micro-abrasions are formed on the bonding lands during forming of the first and second metal core.