Jam prevention device for extrusion process

In an apparatus for forming a continuous thermoplastic workpiece including means for extruding a continuous workpiece of thermoplastic material as an extrudate of predetermined dimension, chamber means for receiving a liquid coolant therein, means for advancing the extrudate from said extruding means through a sizing aperture in said chamber means and through said chamber means, detection means for detecting any outsized variation dimension of the extrudate from a predetermined dimension beyond a certain allowable limit as the extrudate enters said sizing aperture, and means responsive to the detection by said sensing means of an outsized extrudate for moving rectilinearly a linking rod coupled thereto from a first to a second position, a cutter mechanism actuated upon movement of said linking rod from said first to said second position for severing the extrudate,

• wherein the improvement comprises:
• a cutter blade having an extended, curved cutting edge and being coupled to said rectilinearly movable linking rod for actuation thereby;
• and
• said cutter blade being pivotally mounted to a fixed support at a point offset from its center to permit rapid rotation of said cutter blade across the path of the extrudate adjacent said aperture as said linking rod is moved rectilinearly from its first to its second position, thereby amplifying the effect of the rectilinear motion and effecting a rapid severing of the extrudate to prevent further extrudate from being drawn into said chamber means.