Pellet mill

A pellet mill for extruding plastic masses and including a cylindrical pellet die, a rotatable die holder, and means for releasably clamping the die concentrically with an end face of the die holder, said means comprising an annular step recess at the end face of the die holder for receiving the end face of the die, the radially outer surface of the annular step recess diverging conically outwardly in the direction of the die and defining a guiding surface, a series of peripherally spaced apart clamping segments interposed between said guiding surface and the periphery of said die, the radially outer and inner surfaces of the clamping segments respectively matching the conically divergent form of the guiding surface and the curvature of the end face of the die, spring means adapted to urge the clamping segments into clamping engagement with both said guiding surface and said die and auxiliary means actuatable to generate forces to oppose the forces generated by said spring means for disengaging said clamping segments, both the forces generated by said spring means and said auxiliary means being directed at angles .alpha. to the rotational axis of the die holder which are in the range between a value greater than zero and the angle of divergence of said guiding surfaces to produce radially outward movement of the clamping segments on disengagement thereof, members connecting said spring means and clamping segments being provided for transmitting said spring forces to the clamping segments, said members and auxiliary means being adapted to allow movement of the clamping segments in the direction of both said forces.