Method of vacuum forming an object using a flexible mold and an apparatus for vacuum forming an object

Abstract

A method of vacuum forming an object includes heating a plastic sheet. After heating the plastic sheet, a vacuum is applied to pull the sheet against an outer surface of a flexible mold so that the plastic sheet has a formed shape that conforms to a contoured shape of the outer surface of the flexible mold. A rigid core is withdrawn from a cavity in the flexible mold. The flexible mold is then withdrawn from the plastic sheet by applying force to the flexible mold in a single direction, thereby causing flexing of the flexible mold past the undercut. An apparatus for vacuum forming a plastic sheet includes the flexible mold.

1 . An apparatus for forming an object from a plastic sheet comprising:
 a mold having an inner surface defining a cavity and having an outer surface; wherein the outer surface has a contoured shape;   a rigid core configured to fit within the cavity;   a vacuum source positioned to vacuum form the plastic sheet to the outer surface of the mold to form the object having a formed shape that conforms to the contoured shape of the mold, the formed shape including an undercut; and   wherein the mold is flexible, allowing the mold to be withdrawn from the plastic sheet past the undercut by applying force in a single direction after the rigid core is withdrawn from the cavity.   
     
     
         2 . The apparatus of  claim 1 , further comprising:
 a base on which the rigid core is secured;   wherein the base has a series of openings extending around the rigid core; and wherein the vacuum source is in fluid communication with the series of openings.   
     
     
         3 . The apparatus of  claim 2 , wherein the base has a surface on which the rigid core is secured; and wherein each opening of the series of openings extends through the base from the surface on which the rigid core is secured to an opposite surface of the base. 
     
     
         4 . The apparatus of  claim 2 , wherein the series of openings completely surround the rigid core. 
     
     
         5 . The apparatus of  claim 2 , wherein the base has a surface on which the rigid core is secured; wherein the undercut forms a first angle relative to the surface of the base; wherein the force is applied to the mold to withdraw the mold from the plastic sheet past the undercut at a second angle relative to the base; and wherein the second angle is different than the first angle. 
     
     
         6 . The apparatus of  claim 5 , wherein the second angle is a 90 degree angle such that the force is applied perpendicular to the base. 
     
     
         7 . The apparatus of  claim 1 , further comprising:
 a base having a base surface on which the rigid core is secured; and   wherein the force is applied perpendicular to the base surface.   
     
     
         8 . The apparatus of  claim 7 , wherein the undercut is parallel to the base surface. 
     
     
         9 . The apparatus of  claim 1 , wherein a protruding portion of the mold forms the undercut. 
     
     
         10 . The apparatus of  claim 9 , wherein the object is a scale model of a vehicle having a wheel and a bumper, and the undercut is at the wheel or at the bumper. 
     
     
         11 . The apparatus of  claim 1 , wherein the mold is silicone. 
     
     
         12 . The apparatus of  claim 1 , wherein the outer surface of the flexible mold is configured to be coextensive with an inner surface of the object. 
     
     
         13 . The apparatus of  claim 1 , wherein an outer surface of the object is substantially identical to the contoured shape of the outer surface of the flexible mold. 
     
     
         14 . An apparatus for forming an object from a plastic sheet comprising:
 a mold having an inner surface defining a cavity and having an outer surface; wherein the outer surface has a contoured shape;   a rigid core configured to fit within the cavity;   a vacuum source positioned to vacuum form the plastic sheet to the outer surface of the mold to form the object having a formed shape that conforms to the contoured shape of the mold, the formed shape including an undercut;   a base having a surface on which the rigid core is secured;   wherein the base has a series of openings completely surrounding the rigid core; wherein each opening of the series of openings extends through the base from the surface on which the core is secured to an opposite surface of the base; wherein the vacuum source is in fluid communication with the series of openings; and   wherein the mold is flexible, allowing the mold to be withdrawn from the plastic sheet past the undercut by applying force in a single direction after the rigid core is withdrawn from the cavity.   
     
     
         15 . The apparatus of  claim 14 , wherein the force is applied perpendicular to the base surface. 
     
     
         16 . The apparatus of  claim 15 , wherein the undercut is parallel to the base surface. 
     
     
         17 . The apparatus of  claim 14 , wherein a protruding portion of the mold forms the undercut. 
     
     
         18 . The apparatus of  claim 17 , wherein the object is a scale model of a vehicle having a wheel and a bumper, and the undercut is at the wheel or at the bumper. 
     
     
         19 . The apparatus of  claim 14 , wherein the outer surface of the flexible mold is configured to be coextensive with an inner surface of the object. 
     
     
         20 . The apparatus of  claim 14 , wherein an outer surface of the object is substantially identical to the contoured shape of the outer surface of the flexible mold.