Apparatus for producing oriented plastic strap

Apparatus for simultaneously milling and stretching a sheet workpiece which passes through said apparatus in a predetermined direction of travel, comprising:

• a pair of opposed rollers defining a nip therebetween and through which said sheet workpiece is passed so as to be simultaneously milled and stretched as said sheet workpiece passes through said nip in a single pass;
• means for driving said opposed rollers in opposite directions and at sufficiently different lineal surface velocities for simultaneously milling and stretching said sheet workpiece within said nip defined between said pair of opposed rollers;
• and
• heater means disposed about opposite edge portions of said sheet workpiece for heating said opposite edge portions of said sheet workpiece at a location upstream of said nip defined between said pair of opposed rollers so as to increase the degree of flatness of said simultaneously milled and stretched sheet workpiece across the width of said simultaneously milled and stretched sheet workpiece as said simultaneously milled and stretched sheet workpiece passes through said nip defined between said pair of opposed rollers.

Apparatus for simultaneously milling and stretching a sheet workpiece which passes through said apparatus in a predetermined direction of travel, comprising:

• a pair of opposed rollers defining a nip therebetween and through which said sheet workpiece is passed so as to be simultaneously milled and stretched as said sheet workpiece passes through said nip in a single pass;
• and
• means for driving said opposed rollers in opposite directions and at sufficiently different lineal surface velocities for simultaneously milling and stretching said sheet workpiece within said nip defined between said pair of opposed rollers;
• said opposed rollers each having a configuration comprising concave central portions and cylindrical edge portions so as to provide said sheet workpiece with thinner edge portions than central portions when said sheet workpiece is conducted through said nip defined between said pair of opposed rollers such that an increased degree of flatness of said simultaneously milled and stretched sheet workpiece across the width of said simultaneously milled and stretched sheet workpiece, as said simultaneously milled and stretched sheet workpiece passes through said nip defined between said pair of opposed rollers, is achieved.

Apparatus for simultaneously milling and stretching a sheet workpiece which passes through said apparatus in a predetermined direction of travel, comprising:

• die means for extruding a sheet workpiece;
• a pair of opposed rollers defining a nip therebetween and through which said sheet workpiece is passed so as to be simultaneously milled and stretched as said sheet workpiece passes through said nip in a single pass;
• and
• means for driving said opposed rollers in opposite directions and at sufficiently different lineal surface velocities for simultaneously milling and stretching said sheet workpiece within said nip defined between said pair of opposed rollers;
• said die means having a predetermined cross-sectional configuration as defined across the thickness dimension of said sheet workpiece such that said extruded sheet workpiece has thinner edge portions than central portions and such that an increased degree of flatness of said simultaneously milled and stretched sheet workpiece across the width of said simultaneously milled and stretched sheet workpiece, and as considered with respect to the thickness dimension of said sheet workpiece, after said simultaneously milled and stretched sheet workpiece has passed through said nip defined between said pair of opposed rollers is achieved.