Apparatus for transverse cutting of a continuously moving web and a method therefore
An apparatus for transverse cutting of a web has a frame straddling the web path, a side frame on each side of the web path and an upper frame between the two side frames, a circular saw blade suspended in a pendulum arm pivotably connected to the upper frame, a swinging drive for controlling the swinging movement of the saw blade, wherein the pendulum arm is pivotably mounted in a vertically movable sub-frame of the upper frame, and the vertical movement of the sub-frame relative to the upper frame is managed by a lifting drive that is coordinated with the swinging drive. Also disclosed is a method for transverse cutting a web.
1. A method of transverse cutting a web on a web path, said method comprising the steps of—providing a web having a thickness; —cutting through the thickness of said web by providing a pendulum swing of a circular saw blade in a cutting path across the web path, wherein said saw blade is suspended on a pendulum arm which is pivotally supported at a pivot point by a sub-frame, said sub-frame being arranged above the web, said saw blade being operative to swing from a first side position where said saw blade does not have contact to the web on the web path to a second side position where said saw blade does not have contact to the web on the web path, and wherein the moveable sub-frame is in a lowermost position when said saw blade is at either the first or the second side positions; —during the cutting step, automatically moving said sub-frame in an upwards direction from the lowermost position to an uppermost position during the pendulum swing of said saw blade and thereby vertically shifting the pivot point of the pendulum arm, while ensuring that said saw blade cuts through the thickness of the web; and wherein the upward movement of said sub-frame from the lowermost position to the uppermost position is coordinated and controlled such that said sub-frame is at the uppermost position when said saw blade is at a lowermost position.
2. A method according to claim 1 , further comprising a second circular saw blade provided in a parallel pendulum swing configuration.
3. A method according to claim 1 , wherein the web is moving continuously in the length direction of the web path, and the at least one pendulum arm is following the web movement during the swinging, so that said saw blade makes a transversal cut in the continuously moving web.
4. A method according to claim 1 , wherein the cutting path is substantially orthogonal to the web path.