Flexible mold with hinged slits

A flexible, distensible mold for use in fabricating art forms and utilitarian articles, and for use with the aid of air pressure differential enlargement of the shaping cavity, is provided with closeable slits extending from at least a portion of the shaping cavity partly into the mold wall, and cooperating slits extending from the outer wall of the mold into a position which is adjacent to and overlapping the internal slits. With these improved molds a withdrawal bore of the shaping cavity can be greatly enlarged and the side walls can be greatly extended with lower air pressure differentials than would be otherwise necessary. This invention provides a hinging action in the expansion of the side wall which utilizes the flexibility of the mold material to expand the withdrawal bore.

We claim:

1. In an integral, flexible, distensible mold having a body portion including a wall defining a shaping cavity therein, the improvement comprising: a closed, openable first slit to said wall, said first slit extending from at least a portion of the wall from the shaping cavity and only partly through the wall portion of the mold; and a second slit in said wall, said second slit extending from at least a portion of the outer surface of body portion and inwardly only partly through the wall of the mold; said first and second slit defining a strip of flexible, distensible material therebetween, the slits including an enlarged marginal portion thereof at the inner edges thereof.

2. The mold of claim 1 in which said strip is substantially thinner than the thickness of the wall in the region of said first slit.

3. A flexible, distensible mold having a wall defining a shaping cavity; said mold having a first closed, openable slit extending radially outwardly into said wall from said shaping cavity, which first slit extends from the top to the bottom of said cavity, said slit extending only partly through the wall of said mold; said mold also having a second slit, said second slit extending from at least the outer surface of said mold inwardly only partly through said mold; said second slit and said first slit defining therebetween a strip of flexible, distensible wall material, said strip being thinner than the thickness of the wall in the region of said first slit, the slits including enlarged marginal portions thereof at the radial extremes thereof.

4. A flexible, distensible mold having a radially extending flange portion at the top thereof, and having a body portion depending from said flange portion, and a shaping cavity extending through the top portion and into the body portion, said mold having a closed, openable first slit through at least a portion of the mold, said first slit extending from at least a portion of the shaping cavity and only part way through the mold, said mold having a second slit through at least a portion of the mold, said second slit extending from at least a portion of the outer surface of the mold, and inwardly only part way through the mold, said first and second slits defining therebetween a flexible, distensible, integral strip, the slits terminating internally with an enlarged portion thereof.

5. The mold of claim 4 in which said band is thinner than the thickness of the mold wall in the region of the first slit.

6. In an integral, flexible, distensible mold having a body portion including a wall defining a shaping cavity therein, the improvement comprising: a closed, openable first slit to said wall, said first slit extending from at least a portion of the wall from the shaping cavity and only partly through the wall portion of the mold; and a second slit in said wall, said second slit extending from at least a portion of the outer surface of body portion and inwardly only partly through the wall of the mold, said first and second slit defining a strip of flexible, distensible material therebetween and in which mold there is provided two of said second slits on opposite sides of said first slits.