Apparatus for the transversal welding and severing of superposed webs

Claim 1

In an apparatus for the periodical transverse welding and severing of longitudinally advanced wrapper sheets being in a superposed, face-to-face relationship with respect to one another; the apparatus having first and second oppositely rotated, cooperating welding shoes between which the wrapper sheets pass; the first welding shoe being secured to a first rotary shaft and the second welding shoe being secured to a second rotary shaft; each rotary shaft having an axis; at least one of the welding shoes carrying heating means; a knife edge carried by the first welding shoe; a counterface carried by the second welding shoe and cooperating with the knife edge; upon each revolution of the welding shoes the latter simultaneously engage the wrapper sheets from opposite sides for transversely welding and severing the wrapper sheets; the improvement comprising: a. mounting means for radially displaceably securing at least one of said welding shoes to its respective shaft to provide for a displacement of said at least one welding shoe towards its shaft upon abutment with the other welding shoe during encounter therewith; said mounting means including 1. force exerting means for urging the welding shoe radially outwardly relative to the respective shaft; and 2. a stop determining the outermost position of the welding shoe relative to its shaft; the distance between the axes of said rotary shafts being smaller than the sum of the distances of said knife edge and said counterface from the axis of their respective rotary shaft in said outermost position of the welding shoes; b. a wedge-shaped tapered head forming an outer terminal part of said first welding shoe; said head having a leading flank and a trailing flank and ending in an edge constituting said knife edge; and c. two elongated rod-like resilient members secured to said second welding shoe adjacent and parallel to said counterface on either side thereof; during each revolution of said welding shoes one of said rod-like members engages said leading flank of said head for providing a first weld seam on said wrapper sheets and the other of said rod-like members engages said trailing flank of said head for providing a second weld seam on said wrapper sheets; said knife edge, in cooperation with said counterface, severing said wrapper sheets subsequent to forming said first weld seam and prior to forming said second weld seam.