Method and apparatus for transverse cutting

A method of operating an orbital saw for transversely severing elongated, superposed, multi-ply web material comprising:

• providing a frame defining a linear path for elongated web plies,
• continuously advancing said elongated web plies along said linear path,
• rotatably mounting a relatively elongated arm on said frame,
• rotating said arm about an axis skewed with respect to said linear path,
• coupling a four-bar linkage to said arm, said four-bar linkage having means for compensating for said skew,
• rotatably mounting a blade on said four-bar-linkage,
• providing rotating means on said linkage for rotating said blade, rotation of said arm orbiting said blade with the orbit of said blade intersecting said linear path, and
• mounting a grinding stone for said blade on said four-bar linkage so that the grinding stone is always positioned radially inwardly throughout the entirety of said blade orbit whereby centrifugal forces are reduced and cyclic loading is substantially eliminated.

A method of operating an orbital saw comprising the steps of:

• providing a frame defining a linear path for elongated web plies,
• continuously advancing said elongated web plies along said linear path,
• rotatably mounting a relatively elongated arm on said frame,
• rotating said arm about an axis skewed with respect to said linear path,
• rotatably mounting a plurality of blades on said arm,
• compensating for the skew of said arm so that the blades rotate perpendicularly to said linear path, rotation of said arm orbiting said blades with the orbit of said blades intersecting said linear path, and
• mounting a grinding stone for each said blade on said arm so that each grinding stone is positioned radially inwardly of said blade orbit whereby centrifugal forces are reduced and cyclic loading is substantially eliminated.

A method of operating an orbital saw to transversely sever superposed elongated web plies into shorter length products comprising the steps of

• advancing, along a linear path, said superposed elongated web plies having a cross-sectional area of at least about 3.5 in.sup.2 (2200 mm.sup.2),
• providing a 4-bar linkage including first and second bars extending generally parallel to each other and third and fourth bars, each of said bars having a pair of ends,
• connecting said first and second bars adjacent the ends thereof with said third and fourth bars to provide at least one degree of pivotal freedom of said third and fourth bars relative to said first and second bars,
• rotatably mounting a disc blade on each of said third and fourth bars, each of the disc blades having a center,
• rotating said first bar about a first axis to orbit said blades with the orbit of said blades intersecting said linear path and with centers of said disc blades being at least 30 inches (750 mm) apart while skewing said first axis at a minor acute angle to said linear path,
• rotating said second bar about a second axis different from said first axis to compensate for said skewing and to orient said disc blades perpendicular to said web plies in said linear path when severing said web plies,
• mounting a grinding stone and on each of said third and fourth bars so that each grinding stone is positioned radially inwardly of the orbit of said blades throughout the entirety of said blade orbit whereby centrifugal forces are reduced and cyclic loading is substantially eliminated.