Apparatus for producing an endless filter string

Claim 1

APPARATUS FOR SIMULTANEOUSLY LONGITUDINALLY CORRUGATING AND LATERALLY STRETCHING PAPER STRIP MATERIAL OF A PREDETERMINED INITIAL WIDTH PREPARATORY TO LATERALLY GATHERING AND SHAPING THE SAME INTO A GENERALLY CYLINDRICAL STRING ADAPTED TO BE CUT INTO PLUGS FOR USE AS FILTERS FOR FILTER-TIP CIGARETTES, COMPRISING: A PAIR OF ROLLERS OF RIGID MATERIAL MOUNTED ON PARALLEL AXES, EACH OF SAID ROLLERS BEING PROVIDED WITH ALTERNATING CIRCUMFERENTIAL RIDGES AND GROOVES WITH SAID ROLLERS BEING ARRANGED IN NESTED PROXIMITY SO THAT THE RIDGES ON ONE ROLLER EXTEND INTO THE GROOVES IN THE OTHER ROLLER SO AS TO LONGITUDINALLY CORRUGATE PAPER STRIP MATERIAL PASSED BETWEEN SAID ROLLERS, THE RIDGES ON AT LEAST ONE OF SAID ROLLERS HAVING A CROSSSECTIONAL CONTOUR WHICH PROVIDES AT LEAST ONE RELATIVELY SHARP EDGE ENGAGEABLE WITH THE PAPER STRIP MATERIAL SO AS TO SUBSTANTIALLY PREVENT TRANSVERSE GATHERING THEREOF AND THUS SUBSTANTIALLY MAINTAIN THE INITIAL WIDTH OF THE PAPER STRIP MATERIAL IN ITS PASSAGE BETWEEN SAID ROLLERS, WHEREBY THE PAPER STRIP MATERIAL IS STRETCHED LATERALLY AND A LARGE PORTION OF ITS FIBERS ACCORDINGLY PULLED APART.