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Apparatus for cutting thermoplastic filaments or rods with multiple blades in a granulation head of the type which is completely immersed in a cooling liquid, the blades acting with an extrusion die having extrusion orifices arranged in one or more rings centered on the axis of the die and coaxial w

Apparatus for cutting thermoplastic filaments or rods with multiple blades in a granulation head of the type which is completely immersed in a cooling liquid, the blades acting with an extrusion die having extrusion orifices arranged in one or more rings centered on the axis of the die and coaxial with a rotary cutting means carrying cutting blades, wherein the cutting blades have an extrados surface inscribed within a regular convex polygon having an apex angle of 7°or less and an intrados surface having a point of inflection situated at a distance between one quarter and one half of the width of the blade, the remainder of the intrados beyond the inflection point having a profile pattern similar to that of the extrados, and methods for chopping thermoplastics with such apparatus.

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A method for producing sized thermoplastic particles which comprises extruding fluid thermoplastic from a die containing extrusion orifices arranged in one or more concentric circles centered on the die axis and immersed in a cooling liquid, cutting the thermoplastic so extruded through the die usin

A method for producing sized thermoplastic particles which comprises extruding fluid thermoplastic from a die containing extrusion orifices arranged in one or more concentric circles centered on the die axis and immersed in a cooling liquid, cutting the thermoplastic so extruded through the die using a cutting head rotating coaxially to the die and fitted with a plurality of cutting blades, the cutting blades having an extrados surface, with respect to the die face, in the form of an inscribed convex regular polygon having a vertex angle of 173°to 180°and an intrados surface having an inflection point at a distance of from one-quarter to one-half the width of the blade, and the remainder of the intrados surface after the inflection point having a pattern substantially the same as the contour of the extrados, and cooling the thermoplastic to solidify it.