Apparatus and method for selectively coating the inner surface of a hollow body

An apparatus for coating selected portions of the inner surface of a hollow body having a closed end and an open edge, said apparatus comprising:

• a reservoir for containing liquid to be coated onto said hollow body, said liquid having an upper surface level;
• a vent tube having in fluid communication with a variable pressure source;
• a fixture at least partially disposed in said reservoir, said fixture further comprising a pressure tube in fluid communication with said vent tube, means for supporting a hollow body to be coated such that the open edge of said hollow body is below said surface level thereby creating a closed cavity within said hollow body and such that said pressure tube is in fluid communication with said closed cavity, and an upstanding control partition circumscribing and spaced radially outwardly from said pressure tube;
• whereby the level of said liquid within a hollow body supported on said fixture can be raised by creation of an underpressure within said closed cavity to coat the inner surfaces of said hollow body with said liquid, and wherein said control partition Provides an effective upper limit to the rising level of said liquid within said hollow body.

An apparatus for automatically and selectively coating portions of a hollow body having a closed end and an open edge, said apparatus comprising:

• a reservoir for containing a volume of liquid to be coated onto said hollow body, said volume of liquid having a normal level;
• inlet means for providing liquid to said reservoir, and outlet means for draining excess liquid from said reservoir;
• a vent tube having an upper end and being in fluid communication with a variable pressure source, the upper end of said vent tube located above said normal level of said liquid;
• a coating fixture at least partially disposed within said reservoir, said fixture comprising a base, a pressure tube which can be attached in fluid communication with said vent tube, a coating control partition circumscribing and spaced radially outwardly from said vent tube and having an upper Peripheral edge, a plurality of adjustable product supports spaced about the outer periphery of said control partition for supporting an inverted hollow body such that its open edge is partially submerged in said volume of liquid to thereby provide a closed cavity within said closed end of the hollow body above said normal level, and means for dispersing liquid product about the outer periphery of said control partition;
• whereby the level of said liquid within the closed cavity can be raised by application of an underpressure to said closed cavity via said vent tube and pressure tube, the liquid level rising within said cavity about the outer periphery of said control partition until such rising liquid level overflows the upper peripheral edge of said control partition, said partition thereby effectively positively limiting the uppermost liquid level adjacent said hollow body during coating procedures.

A fixture for use in an apparatus for automatically and selectively coating an area of the inner surface of a hollow body with a liquid, said hollow body having a closed end and an open end with an edge defining that open end, said fixture designed to be at least partially disposed in a volume of the coating liquid, said volume of liquid having a normal level, and said fixture comprising:

• a base member;
• a pressure tube attached to said base member;
• means for supporting an inverted hollow body such that its open edge is partially submerged in said volume of coating liquid to thereby provide a closed cavity within said closed end of said hollow body and above the upper surface of said liquid;
• and
• a control partition extending upwardly from adjacent said base and substantially circumscribing said pressure tube, said partition being radially spaced from said pressure tube;
• whereby the liquid level within the closed cavity formed by a hollow body supported on said fixture can be raised by application of an underpressure to said cavity through said pressure tube, and the uppermost raised level of such liquid will be effectively limited by said partition.

A method for automatically and selectively coating portions of the inner surface of a hollow body having a closed end and an open edge, said method comprising the following steps:

• supporting a hollow body in inverted condition on a coating fixture disposed at least partially in a coating reservoir containing a volume of coating liquid having a liquid level, such that the open edge of said hollow body is partially submerged in said volume of liquid to thereby provide a closed cavity within the closed end of said inverted hollow body, said fixture having a coating control partition having a top edge extending upwardly above said liquid level;
• creating an underpressure within said closed cavity to thereby raise the level of said liquid within said closed cavity and on the outer perimeter of said control partition;
• maintaining the underpressure within said closed cavity until the level of said liquid rises above said top edge of said control partition and begins to flow inwardly over said top edge;
• removing the underpressure from within said closed cavity, thereby permitting the liquid to recede to its level;
• and
• removing the coated hollow body from the coating fixture.