Method of making hollow elastomeric bodies

DETAILED DESCRIPTION In accordance with the invention, an annular hollow body having an integral, sharp-cornered flange attached thereto is fabricated by a multiple dip casting process in which a rotating mandrel, preferably in horizontal disposition, is repeatedly dipped into a solution of resing and dried until the desired thickness is achieved.
The solution of resin is found to flow by capillary action into the casting cavity bounded by the body portion of the mandrel and the sharp edge forming boundary of the flange.
Excess dried material is readily removed by stripping along the outline formed at the sharp edge of the flange.
The bladder is smooth, of uniform thickness and transparent.
The bladders are pinhole free and are consistently produced with few rejects.
The edges of the flanges are sharp and clean providing excellent sealing of the bladder in the pump body.
The process is readily adaptable to automated mass production by provision of a line of rotating mandrels disposed over a line of resin solution tanks.
Bladders fabricated by the process of this invention have been subjected to over 2,500 hours of simulated life conditions with no visible signs of degradation.
These and many other attendant advantages of the invention will become readily apparent as the invention becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings.