Method and apparatus for making laminated board with a pocketed core

Claim 3

The invention as defined in claim 1, including the step of applying gas pressure between the core sheet and roll-forming means after the step of drawing the core sheet against the forming elements, to thereby detach the formed core sheet from said elements.

Claim 4

The invention as defined in claim 2, including the step of circulating a heat exchange fluid through said roll-forming means during rotation thereof to maintain said forming elements at a temperature a predetermined value below the temperature of said core sheet.

Claim 5

The invention as defined in claim 2, wherein said forming step includes shaping all of said pockets with a smaller cross-section at the extremity thereof than at the base thereof to thereby facilitate the removal of the core sheet from the forming elements.

Claim 6

Apparatus for making a laminated board with a pocketed core comprising first extruder means for extruding a thermoplastic resin in the form of a sheet at a temperature higher than the melting point of said resin, roll-forming means adjacent said first extruder means and including a rotatable roll having a cylindrical surface portion and having multiple forming elements disposed thereon, said rotatable roll being adapted to receive said sheet and carry it in a downstream direction through less than one revolution of the roll, means for maintaining said forming elements at a temperature lower than said sheet, said multiple forming elements including a first group of elements which are convex relative to the cylindrical surface portion of said roll and including a second group of elements which are concave relative to said cylindrical surface portion, each of said forming elements being separated from adjacent forming elements by a part of said cylindrical surface portion, means for applying a partial vacuum to the region between the sheet and the surface of the roll for urging said sheet toward said roll into engagement with said convex and concave forming elements and with said cylindrical surface portion while the sheet is above its plastic deformation temperature, said forming elements being disposed in an array in which concave and convex elements occur alternately with lines of convex elements extending across lines of concave elements, whereby said sheet is formed with multiple oppositely opening pockets with substantially flat portions of said sheet between adjacent pockets, means adjacent the roll-forming means for changing the direction of advance of said sheet away from the roll-forming means to remove the sheet from said forming elements, second and third extruder means disposed relative to said first extruder means for extruding a pair of face sheets of thermoplastic resin on opposite sides of said core sheet, and means on opposite sides of said face sheets and located at a position downstream of the roll-forming means for guiding and maintaining said face sheets at a fusion bonding temperature and in engagement with the extremities of said pockets in said core sheet after the core sheet leaves the roll-forming means for effecting a joinder of each face sheet to said core sheet.

Claim 7

Apparatus for making a laminated board with a pocketed core comprising first extruder means for extruding a thermoplastic resin in the form of a sheet at a temperature higher than the melting point of said resin, roll-forming means adjacent said first extruder means and including a rotatable roll having a cylindrical surface portion and having multiple forming elements disposed thereon, said rotatable roll being adapted to receive said sheet and carry it in a downstream direction through less than one revolution of the roll, means for maintaining said forming elements at a temperature lower than said sheet, said multiple forming elements including a first group of elements which are convex relative to the cylindrical surface portion of said roll and including a second group of elements which are concave relative to said cylindrical surface portion, each of said forming elements being separated from adjacent forming elements by a part of said cylindrical surface portion, means for applying a partial vacuum to the region between the sheet and the surface of the roll for urging said sheet toward said roll into engagement with said convex and concave forming elements and with said cylindrical surface portion while the sheet is above its plastic deformation temperature, said forming elements being disposed in an array in which concave and convex elements occur alternately with lines of convex elements extending across lines of concave elements, whereby said sheet is formed with multiple oppositely opening pockets with substantially flat portions of said sheet between adjacent pockets, means adjacent the roll-forming means for changing the direction of advance of said sheet away from the roll-forming means to remove the sheet from said forming elements, second and third extruder means disposed relative to said first extruder means for extruding a pair of face sheets of thermoplastic resin on opposite sides of said core sheet, and means on opposite sides of said face sheets and located at a position downstream of the roll-forming means for guiding and maintaining said face sheets at a fusion bonding temperature and in engagement with the extremities of said pockets in said core sheet after the core sheet leaves the roll-forming means for effecting a joinder of each face sheet to said core sheet.

Claim 8

The invention as defined in claim 5 wherein said means for applying a partial vacuum includes a porous member forming at least part of the wall of said concave forming elements, and means connected with the porous members for partially evacuating air from said concave forming elements.

Claim 9

The invention as defined in claim 5 wherein said rotatable roll comprises a hollow drum, a pair of stationary partitions within said drum and being coextensive in the axial direction with the forming elements in the wall of said drum, said partitions and a first portion of the wall of said drum defining a vacuum chamber, said partitions and a second portion of the wall of said drum defining a pressure chamber, gas passage means forming at least part of the wall of said concave forming elements and communicating with the interior of said drum, said vacuum chamber being disposed ahead of said pressure chamber relative to the direction of rotation of said drum.

Claim 10

The invention as defined in claim 7 wherein said gas passage means includes a porous metal member.

Claim 11

The invention as defined in claim 5 wherein said convex forming elements are formed as a tapered boss on the surface of said roll having an extremity narrower than the base and wherein said concave forming elements are formed as a tapered recess in the surface of said roll having an extremity narrower than the mouth.

Claim 12

The invention as defined in claim 5 wherein said means for maintaining said elements at a temperature lower than said sheet comprises fluid passages formed in said roll, and means for supplying a heat exchange fluid to said fluid passages.

Claim 13

The invention as defined in claim 10 wherein said fluid passages comprise a slot of helical configuration defined by the inner surface of said roll, a tube disposed within said slot, means for supplying heat exchange fluid to one end of said tube and means for withdrawing heat exchange fluid from the other end of said tube.

Claim 14

The invention as defined in claim 11, wherein said means for supplying the heat exchange fluid comprises a source of heating fluid and a source of cooling fluid and means for alternately connecting said sources.