Method and apparatus for fabricating molded articles

Claim 3

The method of claim 1, including the further step of interrupting the movement of the molded article while said solid core member is moved in said direction of advance to separate said molded article from the solid core member.

Claim 4

The method of claim 1, in which said hollow core member has a substantially cylindrical wall and a frustoconical wall.

Claim 5

The method of claim 3, in which said substantially cylindrical wall is the internal wall of said hollow core member and is helically grooved, while said frustoconical wall is the external wall of said member and is tapered in the direction of advance of said helical groove.

Claim 6

The method of claim 4, in which said solid core member has a frustoconical external wall tapered slightly in the direction opposite to said direction of advance.

Claim 9

The method of claim 6, in which said hollow core member has a substantially cylindrical internal wall and a frustoconical external wall and in which said internal wall is helically grooved.

Claim 10

The method of claim 7, in which said solid core member has a frustoconical external wall tapered slightly in the direction opposite said direction of advance.

Claim 11

Apparatus for fabricating a molded article having an annular space defined by two generally cylindrical side walls with at least one side wall having a helically threaded surface having a given direction of advance, comprising: first and second mold halves each having a generally semicircular opening; means for moving said mold halves towards and away from each other between first, closed positions and second, open positions, said openings defining a generally cylindrical mold space open at opposite ends of said mold halves when said mold halves are in said first, closed positions; a solid core member located adjacent one end of said mold halves, said solid core member having (1) a first position where the solid core member is concentric within said generally cylindrical mold space defined by said mold halves and seals one end of said generally cylindrical opening and (2) a second position axially spaced from said generally cylindrical opening; means for moving said solid core member between said positions; a hollow core member located at the opposite end of said mold halves, said hollow core member having at least one helically grooved wall with the helical groove having a given direction of advance; support means for supporting said hollow core member for rotation relative to the axis of said generally cylindrical opening; and drive means for simultaneously moving said support means and hollow core member between a first position where said hollow core member is concentric with and surrounds said solid core member in said cylindrical mold space and seals the opposite end of said mold space and a second position axially spaced from said generally cylindrical mold space, said drive means including means for rotating said hollow core member relative to said support means in a direction opposite said direction of advance as said support means and hollow core member are moved from the first position to the second position, while said mold halves remain in said first, closed position.

Claim 12

Apparatus for fabricating a molded article having an annular space defined by two generally cylindrical side walls with at least one side wall having a helically threaded surface having a given direction of advance, comprising: first and second mold halves each having a generally semicircular opening; means for moving said mold halves towards and away from each other between first, closed positions and second, open positions, said openings defining a generally cylindrical mold space open at opposite ends of said mold halves when said mold halves are in said first, closed positions; a solid core member located adjacent one end of said mold halves, said solid core member having (1) a first position where the solid core member is concentric within said generally cylindrical mold space defined by said mold halves and seals one end of said generally cylindrical opening and (2) a second position axially spaced from said generally cylindrical opening; means for moving said solid core member between said positions; a hollow core member located at the opposite end of said mold halves, said hollow core member having at least one helically grooved wall with the helical groove having a given direction of advance; support means for supporting said hollow core member for rotation relative to the axis of said generally cylindrical opening; and drive means for simultaneously moving said support means and hollow core member between a first position where said hollow core member is concentric with and surrounds said solid core member in said cylindrical mold space and seals the opposite end of said mold space and a second position axially spaced from said generally cylindrical mold space, said drive means including means for rotating said hollow core member relative to said support means in a direction opposite said direction of advance as said support means and hollow core member are moved from the first position to the second position, while said mold halves remain in said first, closed position.

Claim 13

Apparatus as defined in claim 9, further including means surrounding said solid core member for removing the molded article from said solid core member as said solid core member is moved from said first position to said second position.

Claim 14

Apparatus as defined in claim 9, in which said hollow core member has a substantially cylindrical wall and a frustoconical wall.

Claim 15

Apparatus as defined in claim 11, in which said substantially cylindrical wall is the internal waLl of said hollow core member and is helically grooved while said frustoconical wall is the external wall and is tapered to produce a minimum thickness between said walls adjacent a free end of said hollow core member.

Claim 16

Apparatus as defined in claim 12, in which both said external walls of said hollow core member have a helical groove therein with both said helical grooves having the same direction of advance and substantially equal pitches and in which said internal and external helical grooves are axially offset from each other.

Claim 17

Apparatus as defined in claim 13, in which said solid core member has an external wall which has a slightly increasing taper from a leading end thereof.