Abstract: A method for the multi-stage compression of a mass in a press, especially an extrusion press containing plastic or elastic masses. The mass to be extruded is precompressed up to a preliminary pressure by the rapid advance of the pressure piston. The initial advance takes place at a high rate without the occurrence of impermissibly high temperatures of the mass or the enclosed gas. The subsequent compression to higher pressure levels takes place in a sequence of stages in each of which the rate of advance of the pressure piston is constant. The rate of advance is increased from stage to stage until a final extrusion pressure is reached. An apparatus for carrying out the method of the invention includes a hydraulic flow rate regulator which is controlled on the basis of signals that are related to the pressure measured in the hydraulic system. The pressure signals may be derived by potentiometers energized by pressure-dependent switches.

Abstract: A method for pressure buildup in a pressing cylinder of a press for a plastic or elastic material, wherein the material, under the influence of the advance of a plunger, is initially precompressed slowly to reach a pre-extrusion pressure and then the pressure is raised and adjusted to the extrusion pressure for the material and maintained at this level. The differential quotient of the pressure rise as a function of time is predetermined as a criterion for reaching the pre-extrusion pressure, and compression is carried out up to this point at a constant low plunger advance rate, with a constant rise in pressure thereafter up to the extrusion pressure.A circuit for carrying out the method includes at least one valve incorporated in the hydraulic feed line to the hydraulic cylinder in which the piston is positioned. The valve is controllable initially by a volume sensor and then by a pressure-rise control means for the hydraulic fluid.

Abstract: A device for pressing out pliable and/or pulverized material in the form of a strand comprising a matrix supported by a matrix pan which can be lifted relative to the container for the material to be pressed out whereby the matrix can be easily detached for cleaning and other services. The length of the matrix relative to the pressure table is such that the emerging strand can be checked directly at the discharge end of the matrix and be easily and accurately cut into sections by a cutting device.