Panel molding method and apparatus
A method and apparatus for molding panels, the apparatus including upper and lower mold dies, a sprayer that sprays resin onto the lower mold die, and a wiper seal ring that's disposed in a position to form a vacuum chamber between the upper and lower mold dies as the mold dies are moving together from an initial sealing position to a closed position. A vacuum source draws air from the vacuum chamber as the mold dies are closing. The vacuum draws trapped air from within the sprayed-on resin to provide a superior class-A surface.
1 . A panel molding apparatus for molding panels, the apparatus comprising:
a lower mold die having a contoured upper face;
an upper mold die having a lower face, the upper and lower mold dies being supported for relative reciprocal motion between an open position displaced from one another and a closed position where the mold dies abut one another and the upper face of the lower mold die and the lower face of the upper mold die define a mold cavity;
a wiper seal ring positioned and configured to be disposed between and in sealing engagement with respective sealing surfaces of the mold dies when the mold dies are positioned at and between the closed position and an initial sealing position between the open and closed positions, forming a vacuum chamber between the upper and lower mold dies;
a vacuum source connectable to the vacuum chamber and configured to draw air from the vacuum chamber; and
a sprayer positioned to spray resin onto the upper face of the lower mold die.
2 . A panel molding apparatus as defined in claim 1 in which the sprayer is configured to co-spray a mixture of resin and reinforcement material onto the upper face of the lower mold die.
3 . A panel molding apparatus as defined in claim 1 in which the sprayer is configured to co-spray a mixture of urethane resin and chopped glass fibers onto the upper face of the lower mold die.
4 . A panel molding apparatus as defined in claim 1 in which the wiper seal ring is carried by one of the mold dies in a position to be in engagement with the other mold die at and between the initial sealing and the closed positions of the mold dies.
5 . A panel molding apparatus as defined in claim 4 in which the wiper seal ring is carried on a vertical outer sealing surface of the upper mold die in a position to be in engagement with a vertical inner sealing surface of the lower mold die at and between the initial sealing position and the closed position of the mold dies.
6 . A panel molding apparatus as defined in claim 1 in which the vacuum source is connected to the vacuum chamber by a port in one of the upper mold die and the lower mold die.
7 . A panel molding apparatus as defined in claim 6 in which the vacuum source is connected to the vacuum chamber by a port in the lower mold die.
8 . A panel molding apparatus as defined in claim 1 in which a vacuum release vent is connected between the vacuum chamber and a gas source, the vacuum release vent being actuable to release the vacuum from the vacuum chamber by admitting air to the vacuum chamber.
9 . A panel molding apparatus as defined in claim 1 in which a vacuum source valve is connected between the vacuum chamber and the vacuum source and is operable to alternately provide and close-off fluid communication between the vacuum chamber and the vacuum source.
10 . A panel molding apparatus as defined in claim 1 in which a vacuum initiation switch is disposed in a position to detect when the mold dies are in a predetermined vacuum initiation position between the initial sealing position and the closed position.
11 . A panel molding apparatus as defined in claim 1 in which a filter is connected between the vacuum source and the vacuum chamber and is configured to remove particulates from evacuated air.
12 . A method for molding panels from co-sprayed resin and reinforcement material, the method including the steps of:
providing a mold assembly including upper and lower mold dies supported for relative reciprocal motion between an open position displaced from one another and a closed position where the mold dies abut one another and where a contoured upper face of the lower mold die and a corresponding contoured lower face of the upper mold die define a mold cavity; co-spraying a mixture of resin and reinforcement material onto the upper face of the lower mold die;
moving the mold dies from the open position toward the closed position;
drawing trapped air from the mixture of resin and reinforcement material; and
continuing to move the mold dies into the closed position.
13 . The method of claim 12 in which:
the step of providing a mold assembly includes the wiper seal ring being carried by one of the upper mold die and the lower mold die in a position to engage and slide along the sealing surface of the other mold die; and
the step of moving the mold dies includes maintaining sliding sealing contact of the wiper seal ring against the sealing surface of the other mold die as the mold dies continue to move from the initial sealing position to the closed position.
14 . The method of claim 12 in which:
the step of providing a mold assembly includes connecting a filter between the vacuum source and the vacuum chamber; and
the step of drawing air from the vacuum chamber includes removing particulates from evacuated air by drawing the air through the filter.
15 . The method of claim 12 in which the step of co-spraying a mixture of resin and reinforcement material includes spraying urethane resin onto the upper face of the lower mold die.
16 . The method of claim 12 in which the step of co-spraying a mixture of resin and reinforcement material includes spraying chopped glass fibers onto the upper face of the lower mold die.
17 . The method of claim 12 in which the step of moving the mold dies from the open position toward the closed position includes supporting the upper mold die on a press platen and actuating the platen to carry the upper mold die downward toward the closed position.
18 . The method of claim 12 in which the step of drawing trapped air from the mixture of resin and reinforcement material includes:
forming a vacuum chamber between the upper and lower mold dies; and
drawing air from the vacuum chamber.
19 . The method of claim 18 in which the step of forming a vacuum chamber includes providing a wiper seal ring positioned and configured to be disposed between and in sealing engagement with respective sealing surfaces of the mold dies when the mold dies are positioned at and between the closed position and an initial sealing position between the open and closed positions.
20 . The method of claim 19 in which the step of drawing air from the vacuum chamber includes:
providing a vacuum source connectable to the vacuum chamber;
connecting a vacuum source valve between the vacuum chamber and the vacuum source in a position to alternately provide and close-off fluid communication between the vacuum chamber and the vacuum source;
positioning a vacuum initiation switch to detect when the mold dies are in a predetermined vacuum initiation position between the initial sealing position and the closed position; and
causing the vacuum source valve to open by causing the upper mold die to move downward past the vacuum initiation position, actuating the vacuum initiation switch to close an electrical circuit powering the vacuum source valve to an open position and providing fluid communication between the vacuum source and the vacuum chamber.
21 . The method of claim 18 in which the step of continuing to move the mold dies into the closed position includes:
once the mold has closed, allowing the mixture of resin and reinforcement material to cure; then
closing the vacuum source valve and venting the vacuum chamber to atmospheric pressure by opening a vacuum vent valve.