Apparatus for forming an aeration groove in a filter

In an apparatus for forming an aeration groove filter, the combination comprising

• a shaft rotatable about a first axis;
• a hollow filter plug alignment drum mounted in cantilevered fashion on said shaft, said drum having a plurality of circumferentially spaced peripherally disposed grooves for sequentially receiving and aligning a plurality of filter plugs and at least one annular slot in the inside surface thereof communicating with said grooves and the interior of said drum to permit a filter plug to project therethrough;
• a cover plate fixedly mounted relative to said drum at an open end of said drum to close off the interior of said drum;
• and
• rotatable means within said drum for forming at least one peripheral groove in each filter plug, said rotatable means being rotatable about a second axis eccentric to said first axis and including a pair of spaced apart rotatable knives with a rotatable cutter between and spacing said knives, each said knife having a peripheral cutting edge for cutting into a filter plug on said alignment drum within a grooving station and said cutter having a plurality of circumferentially spaced cutting edges for removing material from each filter plug between said knives;
• means for rolling the filter plug through said grooving station.