Method of producing gypsum/fiber board

Abstract

A gypsum/fiber board having improved impact resistance is produced by mixing predetermined amounts of fibers, calcined gypsum and water to form a mixture of wetted, loose fibers; laying out a reinforcing mesh over the upper surface of a forming belt; depositing said mixture on said mesh to form a layer of said mixture, said; and compressing said mesh together with said layer of mixture to embed said mesh in the lower surface of said layer to form a board composed of bonded fibers and gypsum with said mesh embedded in the surface thereof.

1. A method of producing a gypsum/fiber board having improved impact resistance, said method comprising the steps of:
 mixing predetermined amounts of water and fibers, and dry calcined gypsum to form a mixture of wetted, loose fibers and dry calcined gypsum;  
 laying out a reinforcing mesh over the upper surface of a forming belt;  
 spacing said mesh above said forming belt;  
 depositing said mixture on said mesh to form a layer of said mixture, said layer of mixture having substantially uniform consistency;  
 allowing a portion of said mixture to pass through said mesh to said forming belt;  
 adding additional water to said formed layer;  
 compressing said mesh together with said layer of mixture to embed said mesh in the lower surface of said layer and to form a board composed of bonded fibers and gypsum with said mesh embedded in the surface thereof; and  
 drying said board to provide a finished board.  
 
     
     
       2. A method of producing a gypsum/fiber board having improved impact resistance, said method comprising the steps of:
 mixing predetermined amounts of fibers and water to form a mixture of wetted, loose fibers;  
 mixing said wetted fibers with a predetermined amount of dry calcined gypsum to form a mixed composition;  
 laying out a reinforcing mesh over the upper surface of a forming belt;  
 spacing said mesh above said forming belt;  
 depositing said mixed composition on said mesh to form a layer of said mixed composition, said layer of mixed composition having substantially uniform consistency;  
 allowing a portion of said mixed composition to pass through said mesh to said forming belt;  
 adding additional water to said formed layer;  
 compressing said mesh together with said layer of mixed composition to embed said mesh in the lower surface of said layer and to form a board composed of bonded fibers and gypsum with said mesh embedded in the surface thereof; and  
 drying said board to provide a finished board.  
 
     
     
       3. The method of  claim 2 , including the additional step of causing a portion of said mixed composition to pass through the openings of said mesh prior to said compression step. 
     
     
       4. The method of  claim 2 , wherein said mesh is vibrated across its width at the point said mixed composition is deposited on said mesh. 
     
     
       5. The method of  claim 2 , including the additional step of adding water to said deposited layer of mixed composition before said formed layer is compressed. 
     
     
       6. A method of producing a gypsum/fiber board having improved impact resistance, said method comprising the steps of:
 mixing predetermined amounts of fibers and water to form a mixture of wetted, loose fibers;  
 mixing said wetted fibers with a predetermined amount of dry calcined gypsum to form a first composition;  
 laying out a reinforcing mesh over the upper surface of a forming belt;  
 spacing said mesh above said forming belt;  
 depositing said first composition on said mesh to form a layer of said first composition, said layer of first composition having substantially uniform consistency;  
 allowing a portion of said first composition to pass through said mesh to said forming belt;  
 adding additional water to said formed layer of said first composition;  
 mixing a low density porous particle mixture with water to form a supply of wetted low density particles;  
 mixing said wetted low density porous particles with a predetermined amount of dry calcined gypsum to form a second composition;  
 depositing said second composition over said first layer to form a second layer having a substantial uniform consistency;  
 mixing said wetted fibers with a predetermined amount of dry calcined gypsum to form a third composition;  
 depositing said third composition over said second layer to form a third layer having a substantial uniform consistency; and  
 compressing said mesh together with said three layers to embed said mesh in the surface of said first layer and to form a board composed of bonded fibers and gypsum with said mesh embedded in the surface thereof; and  
 drying said board to provide a finished board.  
 
     
     
       7. The method of  claim 6 , including the additional step of causing a portion of said first composition to pass through the openings of said mesh prior to said compression step. 
     
     
       8. The method of  claim 6 , wherein said mesh is vibrated across its width at the point said mixed composition is deposited on said mesh. 
     
     
       9. The method of  claim 6 , including the additional step of adding water to said deposited layer of first composition before said deposited layer of first composition is compressed. 
     
     
       10. The method of  claim 1 , contacting a surface of the mesh with a bar or roll, over the forming belt, to space the mesh above the surface of the forming belt. 
     
     
       11. The method of  claim 10 , wherein the bar is a mesh elevating bar and the surface of the mesh contacts the mesh elevating bar, over the forming belt, to space the mesh above the forming belt. 
     
     
       12. A system for producing a gypsum/fiber board having improved impact resistance, comprising:
   a roll of reinforcing mesh having openings,        a forming belt having an upper surface over which the mesh from the roll of reinforcing mesh is laid out;        a mixer for mixing wetted, loose fibers and dry calcined gypsum to form a mixture of wetted, loose fibers and dry calcined gypsum and depositing said mixture on said mesh laid out over the upper surface of the forming belt to form a layer of said mixture, said layer of mixture having substantially uniform consistency, and to allow a portion of said mixture to pass through the openings of said mesh to the forming belt;        means for spacing the mesh above said forming belt;        means for adding additional water to said formed layer;        a compressing station for compressing said mesh together with said layer of mixture to embed said mesh in the lower surface of said layer and to form a board composed of bonded fibers and gypsum with said mesh embedded in the surface thereof; and        a dryer downstream of the compressing station for drying said board to provide a finished board.     
     
     
       13. The system of  claim 12 , wherein said means for spacing comprises a bar or roll for contacting a surface of the mesh, over the forming belt, to space the mesh above the surface of the forming belt. 
     
     
       14. The system of  claim 13 , wherein said means for spacing comprises a mesh elevating bar for contacting the surface of the mesh, over the forming belt, to space the mesh above the forming belt. 
     
     
       15. The system of  claim 14 , wherein said mixer comprises a mixing head comprising a spiked roll. 
     
     
       16. The system of  claim 12 , wherein said mixer comprises a mixing head comprising a spiked roll. 
     
     
       17. The system of  claim 18 , wherein said first mixer comprises a mixing head comprising a spiked roll. 
     
     
       18. A system for producing a gypsum/fiber board having improved impact resistance, comprising:
   a roll of reinforcing mesh having openings,        a forming belt having an upper surface over which the mesh from the roll of reinforcing mesh is laid out;        a first mixer for mixing wetted, loose fibers and dry calcined gypsum to form a first composition of wetted, loose fibers and dry calcined gypsum and depositing said first composition on said mesh laid out over the upper surface of the forming belt to form a layer of said first composition, said layer of first composition having substantially uniform consistency, and to allow a portion of said first composition to pass through the openings of said mesh to the forming belt;        means for spacing the mesh above said forming belt;        means for adding additional water to said formed layer of said first composition;        means for mixing a low density porous particle mixture with water to form a supply of wetted low density particles;        a second mixer for mixing wetted low density porous particles, and dry calcined gypsum to form a second composition and depositing said second composition over said first layer to form a second layer having a substantial uniform consistency;        a third mixer for mixing wetted, loose fibers and dry calcined gypsum to form a third composition and depositing said third composition over said second layer to form a third layer having a substantial uniform consistency;        means for compressing said mesh together with said three layers to embed said mesh in the surface of said first layer and to form a board composed of bonded fibers and gypsum with said mesh embedded in the surface thereof; and        a dryer for drying said board to provide a finished board.     
     
     
       19. The system of  claim 18 , wherein said means for spacing comprises a bar or roll for contacting a surface of the mesh, over the forming belt, to space the mesh above the surface of the forming belt. 
     
     
       20. The system of  claim 18 , wherein said means spacing comprises a mesh elevating bar for contacting the surface of the mesh, over the forming belt, to space the mesh above the forming belt.