Abstract: A plasticating apparatus having a barrel and a screw rotatably disposed therein. The screw has a mixing section including a helical conveying flight to form a helical passage for transporting resinous material along the screw. The mixing section further includes two helical divider flights, each spaced from the conveying flight to divide the helical passage into three channels of varying cyclic depth in the helical direction of the channels. The portions of minimum depth of the channels define wave crests which are helically displaced from each other.

Abstract: A plasticating apparatus having a barrel and a screw rotatably disposed therein. The screw has a mixing section including a helical conveying flight to form a helical passage for transporting resinous material along the screw. The mixing section further includes two helical divider flights, each spaced from the conveying flight to divide the helical passage into three channels of varying cyclic depth in the helical direction of the channels. The portions of minimum depth of the channels define wave crests which are helically displaced from each other.

Abstract: A plasticating apparatus having a barrel and a screw rotatably disposed therein. The screw has a mixing section including a helical conveying flight to form a helical passage for transporting resinous material along the screw. The mixing section further includes a helical, zig-zag barrier flight spaced from the conveying flight to divide the helical passage into channels of varying cyclic depth in the helical direction of the channels. The portions of minimum depth of the channels define wave crests which are helically displaced from each other. The barrier flight has a first section converging toward one side of the conveying flight, and a second segment diverging away from the same side of the conveying flight. The plurality of first and second segments repeat throughout the mixing section.

Abstract: An injection molding apparatus is disclosed which includes a screw having a multichannel wave screw section. In the wave screw section, a helical passage defined by a radially extending helical screw flight is divided into a pair of flow channels by a radially extending helical barrier. The helical barrier is radially shorter than the helical conveying flight and the effective outer width thereof is axially narrower than the helical conveying flight. Each flow channel is provided with an undulating base surface that defines a plurality of wave cycles. The base surface varies in a radial direction between a valley portion and a crest portion for the wave cycle and a wave cycle is defined as extending between consecutive crest portions. The crest portions of one flow channel are helically displaced from the crest portions of the adjacent flow channel.

Abstract: An extruder having a multichannel wave screw is disclosed wherein at least one portion of the screw is provided with a helical passage that is divided into a pair of parallel flow channels. The helical passage is defined by a helical conveying land which extends radially outwardly to a first diameter from the screw root, which defines the bottom surface of the helical passage. To divide the helical passage into the pair of flow channels, a helical barrier land extends radially outwardly to a second diameter which is less than the first diameter. Each flow channel is further characterized by the existence of an undulating screw root which defines a plurality of waves, each with a crest and a valley. The crests of one flow channel are helically displaced relative to the crests of the adjacent flow channel.

Abstract: An injection molding apparatus is disclosed which includes a screw having a multichannel wave screw section. In the wave screw section, a helical passage defined by a radially extending helical screw flight is divided into a pair of flow channels by a radially extending helical barrier. The helical barrier is radially shorter than the helical conveying flight and the effective outer width thereof is axially narrower than the helical conveying flight. Each flow channel is provided with an undulating base surface that defines a plurality of wave cycles. The base surface varies in a radial direction between a valley portion and a crest portion for the wave cycle and a wave cycle is defined as extending between consecutive crest portions. The crest portions of one flow channel are helically displaced from the crest portions of the adjacent flow channel.

Abstract: An extruder having a multichannel wave screw is disclosed wherein at least one portion of the screw is provided with a helical passage that is divided into a pair of parallel flow channels. The helical passage is defined by a helical conveying land which extends radially outwardly to a first diameter from the screw root, which defines the bottom surface of the helical passage. To divide the helical passage into the pair of flow channels, a helical barrier land extends radially outwardly to a second diameter which is less than the first diameter. Each flow channel is further characterized by the existence of an undulating screw root which defines a plurality of waves, each with a crest and a valley. The crests of one flow channel are helically displaced relative to the crests of the adjacent flow channel.

Abstract: In accordance with the present invention an extruder screw having a helical conveying land is provided with a helical barrier land therewithin to form a pair of parallel helical flow channels. Each flow channel includes repeating wave cycles. Each wave cycle is of varying depth, having alternating wave crests and valleys. The wave cycles of the adjacent channels are helically offset so that a wave crest of one channel lies opposite a valley in the adjacent channel. The barrier land is undercut in a manner which facilitates the flow of melt thereacross from one channel to the other, while restricting the flow thereacross of unmelted solids. Solids thus tend to pass through a restriction formed by the wave crest while the melt travels across the barrier flight into the adjacent channel, thereby minimizing the formation of pressure pulses in the extrudate flow. The clearance above the barrier flight is small, and the width of the barrier flight is very narrow so as to impart little energy input i.e.

Abstract: Injection molding apparatus is disclosed for molding degradable synthetic resinous materials such as nylons. A vented injection molding machine includes a barrel, a rotatable reciprocable screw and means for preventing ingestion of a deleterious atmospheric gas such as oxygen. The particular apparatus whereby exclusion of the atmospheric gas may be effected includes a conduit having a terminal end thereof positioned at the vent opening of the injection molding machine barrel. The conduit communicates with a source of inert gas and directs a pressurized current of inert gas into the vent opening during the transient time interval between the end of the injection portion of the molding machine cycle and the plasticization portion of the machine cycle. If desired, the inert gas may flood the vent opening continuously. Both nitrogen and carbon dioxide are suitable inert gases for use with nylon materials.

Abstract: A vented injection molding machine adapted to handle a wide variety of synthetic resinous materials without predrying is disclosed. The molding machine includes a two-stage screw rotatably and reciprocably mounted within a barrel. The barrel includes a pair of ends, a feed opening at one end and a vent opening intermediate the pair of ends. A first stage of the screw essentially completes material plastication. The first stage has a protruding helical screw flight with a first pitch and includes a feed section communicating with the feed opening, a transition section, and a pumping section. A second stage of the screw includes a deep flighted vent section which communicates with the vent opening and the first stage pumping section, a short transition section and a relatively short second pumping section. The second stage also includes a protruding helical screw flight having a second pitch which is greater than the first pitch of the first stage.

Abstract: A plasticating extruder screw is provided with a wave section in which the depth of the material conveying channel varies cyclically over a plurality of cycles. The wave section as a whole provides good pumping performance for metering the extrudate at a uniform rate. The deep valley portions of the wave section minimize heat inputs to the material being fed, and the shallow ridge portions of the wave section assure repeated intensive mixing of the material for providing high quality polymer melts. The minimum channel depth portions are in a balanced relationship about the axis of the screw to avoid lateral thrust problems. Such balance may be achieved in successive cycles of a single channel or as between adjacent channels of a multiple channel screw. The wave may be in the metering section of a single stage screw or in any of the pumping sections of a multiple stage screw.

Abstract: A rotary screw extruder and a method are provided to both devolatilize and dry plasticized resinous hygroscopic materials during extrusion thereof into a finished product of indefinite length. The extruder includes a screw having three successive pumping sections and a pair of vent sections. Each vent section separates two of the successive pumping sections. The first pumping section meters plasticized material throughflow. The intermediate pumping section has partially full channels that permit a continuous, helical passage to interconnect the two vent sections. The partially full channels establish a free surface which promotes devolatilization and drying. The third pumping section pressurizes the devolatilized and dried plasticized material for extrusion through a conventional die orifice. The devolatilizing and drying method begins by controlling the flow rate of plasticized material into a gas removal zone.