Abstract: A method and apparatus for feeding an additive, such as glass fibers, fillers, etc., to a plastic resin in an extruder is disclosed. The additive is fed by means of a screw type feeder into the barrel of a plastics extruder or reciprocating screw plastifier at a location where the resin is molten and the resin pressure is low.

Abstract: An apparatus for hydrolytic degradation of plastics in which plastic material is deposited into a tubular housing via a feed hopper. An elongated screw shaft has a first section in the form of a high pitch screw thread disposed below the feed hopper to receive and advance the material to a second section. The second section of the screw shaft is in the form of a lower pitch thread for compressing the plastic material and transferring it to a longer, third section in the form of kneading discs, from which material passes through an outlet nozzle section to a cyclone separator where trapped gases and liquid may be withdrawn. The tubular housing is vented upstream of the feed hopper and a water inlet pipe is disposed adjacent to the second section of the screw shaft, downstream of the feed hopper. The outlet nozzle section is provided with pressure measuring and regulating means and a liquid level measuring and regulating device.

Abstract: 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.

Abstract: A new extruder screw design incorporating an optimal flight helix angle and flight height in the feed section and metering section and a constantly varying helix angle with a constantly decreasing flight height in the transition section is disclosed; the screw being efficiently fed by use of a grooved section of extruder barrel in the area of the feed section.

Abstract: Disclosed is a screw extruder apparatus, having passages to drain melt as formed into a central bore of the screw, which is physically separated by seal means into a first zone on the feed side advancing plastic toward said seal and a second zone on the opposite side of said seal means into which drained melt passes from the bore and is pumped back toward said seal and out a lateral exit orifice adjacent said seal means. The temperature of the melt in the second zone can be independently controlled. In one embodiment means are provided to maintain an essentially constant pressure in said second zone.

Abstract: A plasticizing device for an injection molding machine for plastics comprises a screw housing having a cylindrical plastic material chamber at one end having a discharge opening. A cylindrical screw is rotatably and axially displaceably mounted in the housing and has a screw head portion adjacent the discharge with an intermediate body portion of reduced diameter adjacent the head portion and a uniform diameter portion on the opposite side of the intermediate portion from the head portion. The uniform diameter portion carries a spiral screw thread which projects radially outwardly from the surface of the screw. A seal ring having an outer periphery engaged with the interior of said screw housing and having an interior diameter greater than and spaced radially outwardly from the intermediate portion of the screw defines a plasticizing material passage with the intermediate portion which connects through a passage defined between a seal washer on the screw which cooperates with the seal ring.

Abstract: In accordance with the process, a continuously fed viscoplastic material is subjected to a vacuum treatment in a thin layer with subsequent formation of a higher pressure zone from the material. Then the material is again subjected to the vacuum treatment in a thin layer, and a second higher pressure zone is formed from the material prior to feeding it to a next production stage. In an apparatus for carrying out the process for vacuum treatment, there is provided a container accommodating an auger having main and auxiliary turns running in opposite directions for feeding the material in a thin layer and for forming higher pressure zones from the material. There are provided a pipe in the container which is connected to a vacuum system for forming a vacuum zone in the container and means returning the material from one of the higher pressure zones back to the vacuum zone. The production process of vacuum treatment is thereby considerably accelerated and the material of better quality is obtained.

Abstract: Extruding apparatus comprises a first screw extruder feeding into the inlet of a second screw extruder, such inlet being located at an intermediate position between the driving means and the discharge of the second extruder. Degassing means which applies a vacuum to the material fed into the second extruder tends to draw off particles of material entrained in the gas which is drawn off. The screw of the second extruder has a first screw portion which acts in a direction to propel the main mass of material from the inlet to the discharge of the second extruder and a second screw portion which acts in the opposite direction to propel the drawn off material from the inlet to an outlet which is located between the inlet and the driving means and which opens into a vacuum chamber. A third screw portion located between the outlet and the driving means acts in the same direction as the first portion and hence toward the outlet.

Abstract: A screw extruder for thermoplastics synthetic materials or elastomers having a screw rotating in a cylinder wherein the screw has a mixing part having a plurality of first grooves at an upstream position thereof inclined in the direction of feed, a plurality of second grooves at a position downstream of the first grooves and also inclined in the direction of feed and a grooveless portion between said first grooves and said second grooves, and the cylinder has a mixing part which surrounds said grooveless portion of the mixing part of the screw and has third grooves therein which extend axially or are inclined in the direction of feed, the number of said first grooves, said third grooves and said second grooves differing. Preferably the number of grooves diminishes in the feed direction that is to say the number of said first grooves exceeds the number of said third grooves and the number of said third grooves exceeds the number of said second grooves.