METODO ED APPARECCHIO PERFEZIONATI PER PRODURRE NASTRI DI LASTICA ORIENTATI IN PARTICOLARE REGGETTE

A method of producing a plastic sheet-strap includes the steps of providing first and second work rollers such that the work rollers rotate in opposite directions and at different lineal surface velocities. The work rollers are spaced apart with respect to each other so as to define a work roller nip therebetween. A pinch roller is provided that is operably associated with the first work roller. The pinch roller and the first roller defining a deaerating nip therebetween. A solid sheet of material having a thickness is fed into the deaerating nip. The material is pinched against the first work roller and moves with rotation of the first work roller to the work roller nip between the first and second work rollers. The material is simultaneously milled and stretched substantially at the nip during a single pass of the solid sheet material through the nip as the rollers rotate in opposite directions and at different lineal surface velocities to form a milled and stretched oriented sheet. The second roller has a concave profile to work the edges of the sheet more than a central region of the sheet. A chill roller is disposed downstream of the second work roller to cool the milled and stretched oriented sheet.