Netstal-maschinen Ag

Netsal Maschinen Ag

Friedrich Laimer

Bernhard Roth

Engelbert Neff

Hermann Neugebauer

A screw plastifying and conveying device includes a screw (5) which has a pull-in zone (I) of constant pitch volume (V.sub.0), a first compression zone (II), and adjacent thereto, i.e. in the injection side, a second compression zone (III). The compression ratio (V.sub.1 :V.sub.0) of the second compression zone (III) is between 1:1.0 and 1.2, while that of the first compression zone is between 1:1.6 and 1:4. This makes it possible, by underdosing, to reduce the melt volume in the second compression zone, thereby achieving stable conveying action over a wide operating range. Molded parts with minimal internal tensions and e.g. also molded parts of glass-clear material with unobjectionable optical properties can thus be produced.

Screw plastifying and conveying device of an injection molding machine

An injection molding machine, comprises, an injection piston which is hydraulically actuated during programmed injection and dwell pressure phases. During a speed-controlled injection phase I, the pressure in a tool or mold cavity is measured and monitored. As soon as the pressure reaches an initial desired value, a pressure surge-free switching to the dwell pressure phase II is effected. During the dwell pressure phase, the pressure in the tool cavity is controlled and a pressure in a hydraulic cylinder for moving the injection piston is measured and monitored. A switch signal is produced from the tool pressure and the hydraulic pressure, by means of which a switching to a solidification phase III is effected without causing pressure surges. The actual pressure value at the instant of switching serves as the initial desired value for the solidification phase III. The hydraulic pressure is controlled during this phase.

Injection molding machine

A feeding screw assembly of a molding machine for plasticizable masses, particularly, plastics and rubber, comprises a passage part of the screw which has a passage therethrough having mixing means therein for intermixing a plasticizable material which passes through the passage. The material is diverted into the mixing passage which extends completely through the length of the mixing part by communicating passages located upstream for the inflow of the material and downstream for the discharge of the material after it is mixed. The construction may also include a passage portion which comprises an annular displaceable part having an end or side bounding a communicating passage upstream and which will move in a direction to close off this passage after a part of the other material has been fed into the mixing passage.

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Reichenburg, Switzerland

Friedrich Laimer