Method of Shortening the Time to Compression Mold a Roofing Shingle or Tile and Apparatus for Facilitating Same

Abstract

A method of shortening cycle time required to compression mold shingle or tile is provided, wherein carrier plates are comprised of a surface material and a base, and receive a thermoplastic material, thereon. The roofing material is applied to the carrier plate and the carrier plate is subjected to induction heating, by which its surface material has its temperature raised, without substantially raising the temperature of the carrier plate base, such that the thermoplastic material applied thereto is kept heated in the compression mold. Cooling of the thermoplastic material is by heat transfer from the carrier plate surface material to the carrier plate base, and with both materials having good heat conduction capability. The carrier plate surface material has a high receptivity to being heated by induction heating relative the carrier plate base. The carrier plates are serially delivered through the process, to the compression mold.

1 . A carrier plate for use in carrying hot, partially molten thermoplastic material during the processing of that material to become a roofing element of the shingle or tile type, wherein the carrier plate comprises:
 (a) a carrier plate base that has heat conduction capability and is comprised of a material that has low receptivity to being heated by induction heating;   (b) a carrier plate surface material having heat conduction capability and is comprised of a material that has high receptivity to being heated by induction heating;   (c) with the carrier plate surface material being in bonded relation to the carrier plate base;   (d) wherein the carrier plate base is responsive to receiving heat transferred thereto from the carrier plate surface material; and   (e) wherein the carrier plate surface material is responsive to being cooled by heat transfer from the carrier plate surface material to the carrier plate base.   
     
     
         2 . The carrier plate of  claim 1 , wherein the carrier plate surface material comprises a metal material. 
     
     
         3 . The carrier plate of  claim 1 , wherein the carrier plate base is at a temperature below 200° F. 
     
     
         4 . The carrier plate of  claim 1 , wherein the carrier plate surface material is substantially thinner than the carrier plate base. 
     
     
         5 . The carrier plate of  claim 1 , wherein the carrier plate surface material comprises a thin skin. 
     
     
         6 . The carrier plate of  claim 1 , wherein the carrier plate surface material is a material of substantially higher electrical resistivity than the electrical resistivity of the carrier plate base. 
     
     
         7 . The carrier plate of  claim 1 , wherein the carrier plate surface material comprises a magnetic material and wherein the carrier plate base comprises a non-magnetic material. 
     
     
         8 . The carrier plate of  claim 1 , wherein the carrier plate surface material is selected from the group consisting of a material containing a substantial amount of any of:
 (i) carbon;   (ii) steel;   (iii) tin;   (iv) tungsten; and   (v) any combination of any of the materials of (i) through (iv).   
     
     
         9 . The carrier plate of  claim 1 , wherein in the carrier plate base is a material selected from the group consisting of a material containing a substantial amount of any of:
 (i) aluminum;   (ii) brass;   (ii) copper; and   (iv) any combination of any of the materials (i) through (iii).