Analyzing and Troubleshooting Single-Screw Extruders

Transcription

1 Analyzing and Troubleshooting Single-Screw Extruders Bearbeitet von Gregory A. Campbell, Mark A. Spalding 1. Auflage Buch. 800 S. Hardcover ISBN Format (B x L): 17,4 x 240,5 cm Gewicht: 1569 g Weitere Fachgebiete > Technik > Verfahrenstechnik, Chemieingenieurwesen, Lebensmitteltechnik > Mechanische und Thermische Verfahrenstechnik Zu Leseprobe schnell und portofrei erhältlich bei Die Online-Fachbuchhandlung beck-shop.de ist spezialisiert auf Fachbücher, insbesondere Recht, Steuern und Wirtschaft. Im Sortiment finden Sie alle Medien (Bücher, Zeitschriften, CDs, ebooks, etc.) aller Verlage. Ergänzt wird das Programm durch Services wie Neuerscheinungsdienst oder Zusammenstellungen von Büchern zu Sonderpreisen. Der Shop führt mehr als 8 Millionen Produkte.

2 Table of Contents Gregory A. Campbell, Mark A. Spalding Analyzing and Troubleshooting Single-Screw Extruders ISBN (Buch): ISBN (E-Book): For further information and order see or contact your bookseller. Carl Hanser Verlag, München

3 Contents Preface V Acknowledgements VII 1 Single-Screw Extrusion: Introduction and Troubleshooting Organization of this Book Troubleshooting Extrusion Processes The Injection Molding Problem at Saturn Introduction to Screw Geometry Screw Geometric Quantitative Characteristics Simple Flow Equations for the Metering Section Example Calculations Example 1: Calculation of Rotational and Pressure Flow Components Example 2: Flow Calculations for a Properly Operating Extruder Example 3: Flow Calculations for an Improperly Operating Extruder Metering Channel Calculation Summary Polymer Materials Introduction and History History of Natural Polymers The History of Synthetic Polymers Characteristics of Synthetic Polymers Structure Effects on Properties Stereochemistry Melting and Glass Transition Temperatures Crystallinity

4 X Contents 2.4 Polymer Production and Reaction Engineering Condensation Reactions Addition Reactions Polymer Degradation Ceiling Temperature Degradation of Vinyl Polymers Degradation of Condensation Polymers Introduction to Polymer Rheology for Extrusion Introduction to the Deformation of Materials Introduction to Basic Concepts of Molecular Size Size Distribution Example Molecular Weight Distributions for Polymers Basic Rheology Concepts Polymer Solution Viscosity and Polymer Molecular Weight Sample Calculation of Solution Viscosity Introduction to Viscoelasticity Measurement of Polymer Viscosity Capillary Rheometers Cone and Plate Rheometers Melt Index and Melt Flow Rate Viscosity of Polymers as Functions of Molecular Character, Temperature, and Pressure Models for Non-Newtonian Flow Resin Physical Properties Related to Processing Bulk Density and Compaction Measurement of Bulk Density Measuring the Compaction Characteristics of a Resin Lateral Stress Ratio Measuring the Lateral Stress Ratio Stress at a Sliding Interface The Screw Simulator and the Measurement of the Stress at the Interface

5 Contents 4.4 Melting Flux Heat Capacity Thermal Conductivity and Heat Transfer Melt Density Solids Conveying Description of the Solid Conveying Process Literature Review of Smooth-Bore Solids Conveying Models Darnell and Mol Model Tadmor and Klein Model Clarkson University Models Hyun and Spalding Model Moysey and Thompson Model Modern Experimental Solids Conveying Devices Solids Conveying Devices at Clarkson University The Solids Conveying Device at Dow Comparison of the Modified Campbell-Dontula Model with Experimental Data Solids Conveying Example Calculation Grooved Bore Solids Conveying Grooved Barrel Solids Conveying Models Solids Conveying Notes The Melting Process Compression Ratio and Compression Rate The Melting Process The Melting Process as a Function of Screw Geometry Review of the Classical Literature Reevaluation of the Tadmor and Klein Melting Data Theory Development for Melting Using Screw Rotation Physics Melting Model for a Conventional Transition Section Using Screw Rotation Physics Melting Models for Barrier Screw Sections XI

6 XII Contents 6.4 Effect of Pressure on Melting Rate One-Dimensional Melting One-Dimensional Melting Model Solid Bed Breakup Melting Section Characteristics Fluid Flow in Metering Channels Introduction to the Reference Frame Laboratory Observations Literature Survey Development of Linearized Flow Analysis Example Flow Calculation Numerical Flow Evaluation Simulation of a 500 mm Diameter Melt-Fed Extruder Extrusion Variables and Errors Corrections to Rotational Flow Simulation of the 500 mm Diameter Extruder Using Fc Frame Dependent Variables Example Calculation of Energy Dissipation Viscous Energy Dissipation and Temperature of the Resin in the Channel Energy Dissipation and Channel Temperature for Screw Rotation Energy Dissipation and Channel Temperature for Barrel Rotation Temperature Increase Calculation Example for a Screw Pump Heat Transfer Coefficients Temperature Calculation Using a Control Volume Technique Numerical Comparison of Temperatures for Screw and Barrel Rotations Metering Section Characteristics

7 Contents 8 Mixing Processes for Single-Screw Extruders Common Mixing Operations for Single-Screw Extruders Common Mixing Applications Dispersive and Distributive Mixing Processes Fundamentals of Mixing Measures of Mixing Experimental Demonstration of Mixing The Melting Process as the Primary Mechanism for Mixing Experimental Analysis of the Melting and Mixing Capacity of a Screw Mixing and Barrier-Flighted Melting Sections Secondary Mixing Processes and Devices Maddock-Style Mixers Blister Ring Mixers Spiral Dam Mixers Pin-Type Mixers Knob Mixers Gear Mixers Dynamic Mixers Static Mixers Mixing Using Natural Resins and Masterbatches Mixing and Melting Performance as a Function of Flight Clearance High Pressures During Melting and Agglomerates Effect of Discharge Pressure on Mixing Shear Refinement Direct Compounding Using Single-Screw Extruders Scaling of Single-Screw Extrusion Processes Scaling Rules Engineering Design Method for Plasticating Screws Process Analysis and Simulations Scale-Up from a 40 mm Diameter Extruder to an 80 mm Diameter Machine for a PE Resin Rate Increase for an 88.9 mm Diameter Extruder Running a HIPS Resin XIII

8 XIV Contents 10 Introduction to Troubleshooting the Extrusion Process The Troubleshooting Process Hypothesis Setting and Problem Solving Case Study for the Design of a New Resin Case Study for a Surface Blemish Case Study for a Profile Extrusion Process Equipment and Tools Needed for Troubleshooting Maddock Solidification Experiment Common Mechanical Problems Flight Clearance and Hard Facing Barrel and Screw Alignment Extruder Barrel Supports First-Time Installation of a Screw Screw Breaks Protection from High-Pressure Events Gearbox Lubricating Oil Particle Seals and Viscoseals Screw Cleaning Common Electrical and Sensor Problems Thermocouples Pressure Sensors Electronic Filters and Noise Motors and Drive Systems Motor Efficiencies and Power Factors Typical Screw Channel Dimensions Common Calculations Energy Dissipated by the Screw Screw Geometry Indices Barrel Temperature Optimization Screw Temperature Profile The Screw Manufacturing and Refurbishing Process Injection-Molding Plasticators Calculations for Injection-Molding Plasticators New Equipment Installations Case Study: A Large Diameter Extruder Purchase Case Study: Extruder and Line Purchase for a New Product Summary for New Equipment Installations

9 Contents 11 Contamination in the Finished Product Foreign Contaminants in the Extrudate Melt Filtration Metal Fragments in the Extrudate Gas Bubbles in a New Sheet Line Gels in Polyolefin Resins Protocols for Gel Analysis Resin Decomposition in Stagnant Regions of a Process Improper Shutdown of Processing Equipment Equipment Purging Oxygen Exclusion at the Hopper Flight Radii Size Drying the Resin Color Masterbatches Case Studies for Extrusion Processes with Contamination in the Product Intermittent Crosslinked Gels in a Film Product Small Gels in an LLDPE Film Product Degassing Holes in Blow-Molded Bottles Contamination in Injection-Molded Parts Splay Defects for Injection-Molded Parts Injection-Molding Case Studies Injection-Molded Parts with Splay and Poor Resin Color Purge Black Color Streaks in Molded Parts: Case One Black Streaks in Molded Parts: Case Two Silver Streaks in a Clear GPPS Resin Injection-Molded Packaging Part The Injection-Molding Problem at Saturn Flow Surging An Overview of the Common Causes for Flow Surging Relationship Between Discharge Pressure and Rate at the Die Troubleshooting Flow Surging Processes Barrel Zone and Screw Temperature Control Water- and Air-Cooled Barrel Zones XV

10 XVI Contents 12.4 Rotation- and Geometry-Induced Pressure Oscillations Gear Pump Control Solids Blocking the Flow Path Case Studies for Extrusion Processes That Flow Surge Poor Barrel Zone Temperature Control Optimization of Barrel Temperatures for Improved Solids Conveying Flow Surging Due to High Temperatures in the Feed Section of the Screw Flow Surging Due to High Temperatures in the Feed Casing Flow Surging Due to a Poorly Designed Barrier Entry for GPPS Resin Solid Blockage at the Entry of a Spiral Mixer Flow Surging Caused by a Worn Feed Casing and a New Barrel Flow Surging for a PC Resin Extrusion Process Rate-Limited Extrusion Processes Vent Flow for Multiple-Stage Extruders Screw Wear High-Performance and Barrier Screws for Improved Rates Case Studies That Were Rate Limited Rate Limitation Due to a Worn Screw Rate Limitation Due to Solid Polymer Fragments in the Extrudate Rate Limited by the Discharge Temperature for a Pelletizing Extruder Large Diameter Extruder Running PS Resin Rate Limited by Discharge Temperature and Torque for Starch Extrusion Vent Flow for a Two-Stage Screw Running a Low Bulk Density PS Feedstock Increasing the Rate of a Large Part Blow-Molding Process

11 Contents 14 Barrier and High-Performance Screws Barrier Screws Wave Dispersion Screws Double Wave Screw Energy Transfer Screws Variable Barrier Energy Transfer Screws Distributive Melt Mixing Screws Fusion Screws Other High-Performance Screw Designs Stratablend Screws Unimix Screws Calculation of the Specific Rotation Rate Melt-Fed Extruders Simulation Methods Compounding Processes Common Problems for Melt-Fed Extruders on Compounding Lines Large-Diameter Pumping Extruders Loss of Rate Due to Poor Material Conveyance in the Feed Section Operation of the Slide Valve Nitrogen Inerting on Vent Domes Secondary Extruders for Tandem Foam Sheet Lines High-Performance Cooling Screws Appendix A1 Polymer Abbreviation Definitions Appendix A3 Rheological Calculations for a Capillary Rheometer and for a Cone and Plate Rheometer A3.1 Capillary Rheometer A3.2 Cone and Plate Rheometer XVII

12 XVIII Contents Appendix A4 Shear Stress at a Sliding Interface and Melting Fluxes for Select Resins A4.1 Shear Stress at a Sliding Interface for Select Resins A4.2 Melting Fluxes for Select Resins Appendix A5 Solids Conveying Model Derivations and the Complete LDPE Solids Conveying Data Set A5.1 Channel Dimensions, Assumptions, and Basic Force Balances A5.2 Campbell-Dontula Model A5.2.1 Modified Campbell-Dontula Model A5.3 Hyun-Spalding Model A5.4 Yamamuro-Penumadu-Campbell Model A5.5 Campbell-Spalding Model A5.6 The Complete Dow Solids Conveying Data Set Appendix A6 Melting Rate Model Development A6.1 Derivation of the Melting Performance Equations for a Conventional Channel A6.2 Effect of Static Pressure on Melting Appendix A7 Flow and Energy Equation Development for the Metering Channel A7.1 Transformed Frame Flow Analysis A7.1.1 x-directional Flow A7.1.2 z-directional Flow A7.1.3 z-directional Flow for Helix Rotation with a Stationary Screw Core and Barrel A7.1.4 z-directional Flow Due to a Pressure Gradient A7.2 Viscous Energy Dissipation for Screw Rotation A7.2.1 Viscous Energy Dissipation for Screw Rotation: Generalized Solution

13 Contents A7.2.2 Viscous Energy Dissipation for Screw Rotation for Channels with Small Aspect Ratios (H/W < 0.1) A7.3 Viscous Energy Dissipation for Barrel Rotation A7.3.1 Viscous Energy Dissipation for Barrel Rotation: Generalized Solution A7.3.2 Viscous Energy Dissipation for Barrel Rotation for Channels with Small Aspect Ratios (H/W < 0.1) Author Subjekt XIX