Frenkel C-d Aktiengesellschaft

Paul Meyer

An extrusion apparatus having a barrel and a rotatable threaded screw coaxially positioned therein is disclosed. The apparatus includes an upstream inlet section having an opening therein for receiving material to be processed by the apparatus, a compression section downstream of the inlet section, and a mixing or plasticizing section downstream of the compression section. The interior surface of the barrel is provided with an undercut therein which intercommunicates the feed opening with the compression section and has a portion thereof which extends downstream in the compression section about the interior surface of the barrel with a continuously decreasing cross-sectional area. The undercut may be formed in a cylindrical insert carried within the barrel and, in an alternate embodiment, a second undercut cylindrical insert positioned about the first insert and rotatable relative thereto may be employed to vary the cross-sectional area of the undercut.

Screw extruders

This invention provides in a continuously operating device having a mixing section comprising opposite-handed helical threads in each of the two relatively rotatable components which threads vary in cross-sectional area in complementary fashion so as to produce a layer-by-layer material transfer and shear working between the said components, that the said opposite handed helical threads in said mixing section complement one another substantially also in respect to their helix-angles to the extent that if one helix angle is between 0.degree.and 45.degree. the other is between 45.degree. and 90.degree., to bring about, viewed with respect to the shear-plane-area, a subdivision sufficient for the mixing and compounding requirement.

Mixing apparatus

A continuous mixer comprising at least one mixing zone formed by a Transfermix geometry in which the number of starts of the helical thread changes for each of the components along the length of said Transfermix zone in the opposite sense to the change of the cross-sectional area of helical grooves on said component, whereby when in operation a medium moves along said Transfermix zone, portions thereof are successively transferred between the grooves of facing helical threads as giver and taker and whereby grooves of larger cross-sectional area are of greater widths than grooves of small cross-sectional area; in a preferred embodiment the mixer has a driven rotor and stationary barrel, the helical threads thereon being of opposite hand and the number of starts facing one another at any cross-section of the Transfermix zone is such as to make a substantially constant product.

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Wiesbaden, Germany

Paul Meyer