Brennan - Chapter 4 10072002

Brennan - Chapter 4 10072002 - Roman aqueduct Positive...

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Unformatted text preview: Roman aqueduct Positive displacement pump Figure 4.1 Schematic of pumping principles Centrifugal pump ' Figure 4.2 Schematic of a single screw extruder (Reifenhfiuser) Non-intermeshing lntermeshing V \ 1,, \\\ / V y A- 4' 'fli’ ’0 fl \\ \\“ 7/,7// \\§. \I/éfl \\\\\\\ :\ Figure 4.3. Schematic of different twin screw extruders Hopper Bane] Cooling lines Screw Band heateis EthUdate 2 Transmon zone Meteling zone (Melting) (Pumping) Solids conveying zone (Compaction) De Figure 4.4 Schematic of a plasticating single screw extruder ¢ Figure 4.5 Schematic diagrém of a screw section 0 1 00 200 300 400 500 AP (bar) Figure 4.6 Screw and die characteristic curves for a 45 mm diameter extruder with an LDPE 0 5D 10D 15D 20D 250 Figure 4.7 Conventional extruder pressure distribution seaI thermal insularor 9T°°V°S cooling lines heated barrel Figure 4.8 Schematic diagram of the grooved feed section of a single screw exlruder grooved feed without decompression grooved feed with decompression N=160 rpm 0 5D 10D 15D 20D 25D Figure 4.9 Grooved feed extruder pressure distribution O 100 200 300 400 500 AP (bar) Figure 4.10 Screw and die characteristic curves for a grooved feed 45 mm diameter extruder with an LDPE o N=185 rpm 0 N=160 rpm v N=120 rpm 1: N= 80 rpm 0 5 10 15 20 25 ApD mNnL Fig. 4.11 Dimesionless screw charactristic curves for conventional and grooved feed extruders Solid bed Unwnapped channel Melt pool 2 Barrel Leading flight Trailing flight W (b) Figure 4.12 (a) Solids bed in an unwrapped screw channel and (b) screw channel cross section ‘0 )(/W at barrel surface M W at screw root Reduced soild bed width, W 579111315171921232527 Turns Figure 4.13 Predicted (Tadmor Model) and experimental solids bed profile arrier flight Maillefer screw Barrier screw Figure 4.14 Schematic diagram of screws with different barrier flights 0 Operating points Less restrictive die (Thick sheet) Deep channel screw Deep channel screw (Higher heater temperatures) Shallow channel screw Restrictive die (Thin film) Figure 4.15 Screw characteristic curves (NewtOnian) ° Grooved Feed O . 1 ° Conventional N (kg - min / hr) 0 m n .3 1O 50 100 200 D(mm) ‘ Figure 4.16 Throughput for conventional and grooved feed extruders Bad design Improved designs V A ———-——> Cost increase Figure 4.17 Extrusion profile designs 4.2.1 Sheeting Dies One of the most widely used extrusion dies is the coat-hanger sheeting die. A sheeting die, such as depicted in Fig. 4.18 is formed by the following elements: - Flex lips: for fine tuning when generating a uniform profile Choker bar FIex-llp Heaters Removable lowerle Manifold Figure 4.18 Cross section of a coat-hanger die Manifold 20 A- Pressure (bar) 4; O approach Choker bar Figure 4.19 Pressure distribution in a coat—hanger die fix my“ .‘ a mWWfifiw§¥$§¥ , Figure 4.21 Schematic of a spider leg tubing die Figure 4.22 Schematic of a cross—head tubing die used in film blowing Spiral mandrel manifold Figure 4.23 Schematic of a spiral die ...
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This note was uploaded on 07/17/2011 for the course EMA 4666c taught by Professor Brennan during the Spring '08 term at University of Florida.

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Brennan - Chapter 4 10072002 - Roman aqueduct Positive...

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