Abstract: A machine for simultaneously forming helical threads or fins on the exterior of first, second and third elongated cylindrical workpieces, the machine having first, second and third arbor blocks arranged in a common plane and spaced about a center point in the plane, having first, second and third thread or fin forming discs rotatably affixed respectfully to the first, second and third arbor blocks, and having first, second and third guides longitudinally displaceably and rotationally receiving respectively the first, second and third workpieces so that the first workpiece is guided by the first guide between the first and second discs, the second workpiece is guided by the second guide between the second and third discs and the third workpiece is guided by the third guide between the first and third discs, rotary energy being coupled to at least one of the discs. In an alternate embodiment four elongated cylindrical members are provided with threads or fins.

Abstract: A method for grinding of material in a ring roller mill having at least one grinding ring, at least one roller fitted in the grinding ring and at least one unit fitted between the roller and the grinding ring. The method includes the steps of operating the mill at a subcritical speed and at a grinding pressure above 40 MPa, placing the unit in the path where compacted material is released from the ring at a certain distance from a point P, which is the point on the ring where the material is released, in such a way that the unit is hit by agglomerates formed during operation at an angle between 60.degree. and 120.degree., said angle being between the surface of the unit and the direction of incidence of the material, after the latter is released from the grinding ring, and that the loosened material is distributed over the draw-in-zone in front of the roller and over the roller.