The present invention relates generally to apparatus for folding a continuous length of web material along a longitudinal fold line, and more particularly to a web folding apparatus having novel features which enable highly efficient folding of a continuous length web material without forming wrinkles or gussets and without marking the web, and which facilitate on-going adjustment to accommodate different type web materials.
Apparatus for folding continuous length web material along a longitudinal fold line as the web material is moved longitudinally are generally known. Such apparatus find particular application in the folding of paper web material as it is passed from a printer to a cutter and sheeter. One type of apparatus for folding web material employs a frame on which transverse entrance and exit rollers are mounted for passage of a web material from the entrance to the exit roller and between which a fold forming mechanism is supported for cooperation with the entrance and exit rollers to fold the web material longitudinally. A significant problem which exists with known web folding apparatus is the formation of wrinkles or gussets at the fold line and marking of the web material in the area of the fold. While the problem of web marking is of particular significance in web folding apparatus employed in the printing industry, the problem of wrinkling or gusseting adversely affects the folding of substantially any web material which is folded generally longitudinally thereof.
Another significant problem found in the known prior web folding apparatus is that they are generally incapable of adjustment during movement of the web material, particular as affects adjustment of the fold former plow, so that shutdown of the apparatus is required for making fine adjustments as may be required to reduce problems of wrinkling or gusseting and marking of the web material, thus adding significantly to the cost of operation.
Still another problem which must be confronted in the longitudinal folding of many web materials is the tendency for the folded portion of the web to unfold following initial folding. While prior known web folding apparatus have attempted to address this problem, the various means suggested, such as goose neck type arm supported rollers and the like for engaging the folded web generally at the fold line, have not been found satisfactory.