Claims
- 1. A male and female distensible elastomeric mold including an outer female portion having an integral radially extending annular flange adjacent its upper portion for being supported on a supporting edge, said female portion having an internal cavity containing considerable undercut back draft portions, said mold also including an inner male portion in said cavity and forming an annular space with said female portion that defines the shape of an article to be produced in said mold, said outer mold portion being expandable when vacuum is applied thereto so as to withdraw from an article produced in said mold and said inner mold portion collapses inwardly when vacuum is applied thereto so as to be withdrawn from the interior of said article produced in said mold.
- 2. The mold as set forth in claim 1 further characterized in that said annular flange on said outer female portion has a smooth and rounded edge.
- 3. The mold set forth in claim 1 further characterized in that said inner and outer mold portions are of sufficient thickness and strength so that they are self-supporting without distortion when said annular space is poured full of material to be hardened therein.
- 4. The mold set forth in claim 2 further characterized in that said inner and outer mold portions are of sufficient thickness and strength so that they are self-supporting without distortion when said annular space is poured full of material to be hardened therein.
- 5. The mold set forth in claim 1 further characterized in that said inner mold portion has recess means along its interior to cause orderly collapse of said inner mold portion when vacuum is applied thereto.
- 6. A generally hollow and one-piece distensible elastomeric mold for forming an article with an internal aperture or the like, said mold having an integral radially extending annular flange adjacent its upper portion for being supported on a supporting edge, said mold having an internal cavity containing considerable undercut back draft portions and which defines a side wall of said mold, said side wall being of such thickness that it is self-supporting without distortion when said cavity contains material poured therein, said mold having mold inner members that are integral with and extend inwardly from said side wall and engage each other so as to define an aperture in the material being formed, said members being withdrawable from said aperture when said mold is distended from the article formed therein, to thereby provide an article having an internal aperture.
- 7. The mold set forth in claim 6 further characterized in that said flange is of sufficient thickness and strength so as to be self-supporting, said flange also has a rounded smooth lower surface that can form a seal with said supporting edge.
REFERENCE TO A CO-PENDING RELATED APPLICATION
This application is a continuation of U.S. Application Ser. No. 403,197, filed Oct. 3, 1973, now abandoned, which was a division of U.S. Application Ser. No. 222,141, filed Jan. 31, 1972, entitled "Apparatus For Molding Articles", which issued as U.S. Pat. No. 3,776,683 on Dec. 4, 1973.
The invention pertains to molding devices of the type utilizing a one-piece and generally hollow, distensible and flexible mold which has an interior configuration corresponding to that of the finished product. Fluid pressure differential is caused to act on the flexible mold to expand it, consequently causing its separation from the finished article, and thereby permit the article to be removed from the mold, notwithstanding the backdraft portions.
An example of a prior art device of this general character is shown in the U.S. Pat. No. 2,124,871, issued July 26, 1938 to Beal and entitled "Method and Apparatus for Molding Articles". The Beal apparatus was severely limited as to the articles which could be made with it. More specifically, the said Beal patent advocated the use of a very thin flexible matrix which distorts when filled with fluid material, thereby resulting in distortion and unfaithful reproduction of the pattern. Furthermore, the said patent utilized a matrix in which it was necessary to clamp the flange to the vacuum pot to effect the necessary seal and this shortcoming severely limited the production. Other prior devices required laborious and time consuming set-up and disassemble operations. Furthermore the filling of the mold with fluid material was awkward and difficult.
The present invention provides molds for molding seamless articles and comprises a generally hollow, one-piece, distensible, flexible mold having a side wall of sufficient thickness whereby it is self-supporting and supports the weight of the material poured therein without distortion of the mold. Means are provided for applying differential pressure on the mold to thereby cause the mold to distend or expand and separate from the finished article therein. The thick-walled mold is only expanded sufficiently to be able to withdraw the article, thereby contributing to good life of the mold.
Another aspect of the invention relates to a mold which has a thick and self-supporting, radially extending annular flange which forms a seal with a vacuum pot in which the mold is located. The arrangement is such that the pot and the mold form an annular chamber from which a vacuum is drawn to thereby distend and expand the mold into the chamber, while at the same time, the flange cooperates with the edge of the pot to maintain the seal as the mold is generally retracted from the article. As a result, there is no need to attach the mold to the vacuum pot, but is only necessary to simply seat the mold on the pot and apply the vacuum, the pot and mold automatically forming a seal therebetween which performs its sealing function regardless of movement of the mold flange relative to the pot.
Another aspect of the invention relates to a mold having female and male portions wherein the female portion is expanded and the male portion is collapsed so the mold can be withdrawn from the finished article located between the female and male mold portions.
Still another aspect of the invention relates to a mold having inner members that extend inwardly from the side wall of the mold so as to define an aperture in the finished article, and where the inner members are withdrawn from the aperture in the article along with the side wall of the mold.
US Referenced Citations (7)
Divisions (1)
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Number |
Date |
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222141 |
Jan 1972 |
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Continuations (1)
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Number |
Date |
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403197 |
Oct 1973 |
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Patent Grant
4093175
