Structural sandwich plate members

Abstract

A structural sandwich plate member comprises first and second outer plates and a core of plastics or polymer material. A plurality of lightweight forms are disposed between the outer plates so that the core material forms ribs extending in two substantially orthogonal directions. The lightweight forms are formed of a fire resistant insulating material, such as mineral wool, preferably surrounded by a barrier to prevent the insulating material being soaked by the liquid form of the plastics or polymer material during injection of the core. The barrier may take the form of a hollow tube in which the insulating material is placed or a coating applied by dipping or spraying or a sheet material such as metal foil, felt, mineral cloth, etc.

1 . A structural sandwich plate member comprising: first and second outer metal plates; a core of compact plastics or polymer material bonded to said outer plates with sufficient strength to transfer shear forces therebetween; and a plurality of relatively lightweight forms disposed within said core; wherein said lightweight forms are made of a fire resistant insulating material.  
   
   
       2 . A structural sandwich plate member according to  claim 1  wherein each of said lightweight forms comprises a barrier impermeable to the liquid form of said plastics or polymer material between said fire resistant insulating material and said core.  
   
   
       3 . A structural sandwich plate member according to  claim 2  wherein said barrier comprises an elongate hollow tube which is filled with said fire resistant insulating material.  
   
   
       4 . A structural sandwich plate member according to  claim 2  wherein said barrier comprises a coating which has been applied to blocks of said fire resistant insulating material by spraying or dipping.  
   
   
       5 . A structural sandwich plate member according to  claim 2  wherein said barrier comprises a sheet material wrapped around said fire resistant insulating material.  
   
   
       6 . A structural sandwich plate member according to  claim 5  wherein said sheet material is selected from the group comprising metal foil, felt, mineral cloth and plastics or polymer sheet materials.  
   
   
       7 . A structural sandwich plate member according to any one of  claims 1  to  6  wherein said fire resistant insulating material comprises mineral wool.  
   
   
       8 . A structural sandwich plate member according to any one of  claims 1  to  6  wherein said fire resistant insulating material has a density in the range of from 30 kg/m3 to 200 kg/m3.  
   
   
       9 . A structural sandwich plate member according to any one of  claims 1  to  6  wherein said fire resistant insulating material has an ignition point and a melting point each greater than 1000° C.  
   
   
       10 . A method of manufacturing a structural sandwich plate member comprising the steps of: providing first and second outer metal plates in a spaced-apart relationship with a plurality of lightweight forms located therebetween; injecting uncured, unfoamed plastics or polymer material to fill the space defined between said outer plates and said lightweight forms; and allowing said plastics or polymer material to cure to bond said outer plates together with sufficient strength to transfer shear forces therebetween; wherein said lightweight forms are made of fire resistant insulating material.  
   
   
       11 . A structural sandwich plate member according to  claim 7  wherein said fire resistant insulating material has a density in the range of from 30 kg/m3 to 200 kg/m3.  
   
   
       12 . A structural sandwich plate member according to  claim 7  wherein said fire resistant insulating material has an ignition point and a melting point each greater than 1000° C.  
   
   
       13 . A structural sandwich plate member according to  claim 8  wherein said fire resistant insulating material has an ignition point and a melting point each greater than 1000° C.