Method for obtaining drain-cast hollow articles

A method for drain-casting a slip to very rapidly obtain a substantially hollow molded article automatically without substantial manual operations, by the use of an apparatus comprising a divisible mold including an upper mold portion, a lower mold portion, and at least two side mold portions to form a mold cavity, the mold portions being moveably supported by outer supporting members, each mold portion including a pressure-proof airtight vessel and a filter member inside the vessel, said filter member containing a water drainage means, said water-drainage means being communicated with the openings outside of the vessel, one of said lower or upper mold portion having a slip supply duct;

• which method comprises the steps of
• filling the mold cavity with a slip supplied through the slip supply duct,
• pressurizing the slip to facilitate deposition of the slip onto the filter members of the mold to a desired thickness, cohesion of the deposited slip onto the filter members being effected and water being drained from the mold,
• adjusting the position of the slip supply duct downward and draining the undeposited slip remaining in the mold cavity through the slip supply duct,
• thereafter in the presence of the cohesion, applying compressed air to the water-drainage means of the upper and lower mold portions to exude some water and from a water film between the filter members and the resulting hollow molded article cohered on the filter members,
• removing the upper and lower mold portion in the presence of the water film, while firmly holding and supporting the cohesion without vacuum the freshly molded article between the filter members of the side mold portions in a suspended fashion to prevent the hollow article from cracking, breaking and deforming,
• thereafter applying a receiving stand under the partly demolded article thus held and supported, removing the side mold portions by application of compressed air to the water-drainage means of the side mold portions to exude some water and form a water film between the filter members and the molded article cohered on the filter members, and demolding the molded article in the presence of the water film on the stand without deformation or damage of the molded article.