Method and apparatus for manufacturing building panels

A method for making a foam-filled building panel, comprising:

• providing a frame having a periphery that includes a front peripheral frame surface and a rear peripheral frame surface, the frame defining a cavity, the front frame surface defining a front opening and the rear frame surface defining a rear opening, where the frame has a thickness defined between the front peripheral frame surface and the rear peripheral frame surface;
• providing a top planar shelf having a lower surface, and a bottom planar shelf having an upper surface;
• providing a plurality of spacers, each having an upper surface and a lower surface, and a height defined between the upper surface and the lower surface, and placing the lower surfaces of the plurality of spacers against the upper surface of the bottom planar shelf at spaced-apart positions, where the heights of the plurality of spacers are the same as the thickness of the frame;
• placing the lower surface of the top planar shelf over and in contact with the front peripheral frame surface to close completely the front opening, and the upper surface of the bottom planar shelf over and in contact with the rear peripheral frame surface to close completely the rear frame opening;
• applying a first force against the top planar shelf and a second force against the bottom planar shelf;
• injecting an amount of an expandable polymer through an aperture in the frame into the cavity, and closing the aperture;
• maintaining the applied forces for a time sufficient for the expandable polymer to expand and fill the cavity, and to form a stable expanded foam;
• and
• releasing the first and second forces and removing the top and bottom planar shelves from the front and rear frame surfaces to form the foam-filled building panel;
• wherein:
• the applied first force and applied second force are sufficient to maintain the top and bottom planar shelves in contact with the front peripheral frame surface and the rear peripheral frame surface of the frame while the expandable polymer is expanding and filling the cavity, the top planar shelf and the bottom planar shelf have a rigidity sufficient to maintain planarity against the applied first and second forces and an expanding force of the expandable polymer, and wherein lower surface of the top planar shelf contacts the upper surfaces of the plurality of spacers, whereby the plurality of spacers define a minimum distance between the top planar shelf and the bottom planar shelf during the application of the applied force to limit crushing of the frame beyond such minimum distance.