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Mechanical Properties in 6061 Aluminum Processed by Equal Channel Angular ExtrusionTsai, Meng-shan 14 July 2004 (has links)
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Analysis of plastic flow within the die and die deformation during extrusion for CPU heat sinksShen, Chun-yen 11 September 2006 (has links)
CPU heat sinks with high efficiency of heat transfer are greatly demanded for a personal computer with high-speed computational ability. In recent years, the manufacturing technology of CPU heat sinks has got much attention and becomes indispensable for developing the high-performance CPUs.In this study, some different design criteria for the flow guide and die are proposed during an extrusion process with complex cross-sectional shapes, such as CPU heat sinks. The plastic flow pattern of the billet inside the die cavity is analyzed by using a commercial finite element package ¡§DEFORM 3D¡¨.The extrusion load, the stress and strain distribution of die, and the curvature of the product are investigated. Taguchi method is used to find the optimum extrusion condition of the die parameters. In addition, the experiments of extrusion using Al 6061 were carried out. The plastic flow pattern of the billet within the die and the dead metal zones were observed. The experimental data were compared with the analytical values to verify the validity of the proposed analytical models.
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Preparation And Characterization Of Organoclay-polypropylene Nanocomposites With Maleic Anhydride Grafted Polypropylene CompatibilizerYilmaz, Sule Seda 01 June 2011 (has links) (PDF)
The aim of this study was to improve the mechanical properties &ldquo / Moplen&rdquo / EP300L
which is a heterophase copolymer. Polymer blends and nanocomposites were
prepared by melt compounding method in a twin screw extruder. Nanofil® / 5 (N5) and
Nanofil® / 8(N8) were used as the organoclays, and maleic anhydride grafted
polypropylene (M) was used as the compatibilizer. The effects of additive
concentrations and types of organoclays on the morphology, mechanical and thermal
properties were investigated.
Organoclay loading over 2 wt% prevented the intercalation mechanism resulting in
large aggregates of clay, thus the material properties became poor even in the
presence of compatibilizer. Compatibilizer addition improved the intercalation ability
of the polymer, however a substantial increase in mechanical properties was not
obtained up to 6 wt % loading of the compatibilizer.
XRD analysis revealed that intercalated structures were formed with the addition of
compatibilizer and organoclay. The nanocomposites that were prepared with N5 type
organoclay showed delaminated structures at 6 wt % compatibilizer loading.
v
Nanofill ® / 5 exhibited the highest improvements in mechanical properties, since the
degree of organoclay dispersion was better in Nanofill ® / 5 containing
nanocomposites in comparison to Nanofill ® / 8 containing ones. The DSC analysis
indicated a insignificant reduction in the melting temperature of the ternary
nanocomposites.
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The effects of deformation temperature on the microstructural development in Al-Mg alloy processed by equal channel angular extrusionChen, Yi-Chi 16 August 2002 (has links)
none
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Studies of the Application of Empirical Viscosity Models and Fuzzy Logic to the Polymer Extrusion Process ControlChen, Zwea-long 20 May 2003 (has links)
In the polymer extrusion process the product quality like mechanical, optical, electrical properties and homogeneity etc. can be achieved by controlling the melt temperature, melt pressure or viscosity within a narrow fluctuation range. In the earlier studies there are many literatures in connection with the extrusion quality and related quality controls; i.e. temperature control, pressure control and viscosity control. In each of the control strategies, it is believed that the most effective to maintain product quality utilising viscosity control, because a polymer viscosity closely correlates with its composition and molecular distribution, and hence the characteristic of the material.
In the viscosity control strategy, viscosity is an induced variable calculated from either the (1) flow rate and pressure drop with in-line rheometer or (2) melt temperature, screw speed (or pressure), geometrical dimensions of extruder, and extrusion material constants without in-line rheometer; the former method may interfere the output rate while the latter one does not.
On the demand of using viscosity-measuring instruments as sensors to control the quality of the products, we developed an empirical off-line viscosity model, which is used to derive the extrusion viscosity models in the control process without in-line rheometer. The off-line viscosity model is proved more accuracy than other previous suggested models, such as WLF and Andrade¡¦s equations, to fit the experimental data. Polypropylene (PP) was used in this study to test the effectiveness of the extrusion viscosity models. Comparing the calculated results, it was found that the viscosity characteristics obtained by the extrusion viscosity models are in agreement with those obtained by using an in-line rheometer. Both methods can be used to obtain the viscosity in the polymer extrusion process.
The objective of this study is to develop extrusion viscosity models together with collected data from several experimental tests and template rule-base to build a Multi-Input Multi-Output (MIMO) fuzzy logic closed-loop controller for the plastics extrusion control. The objective of this controller is to eliminate process variations and to produce the polymer of consistent quality. The fuzzy logic is provided for designing the MIMO closed-loop controller because it is suitable for applying to the polymer extrusion process control with such advantages as handling complex problems like non-linear, time varying behaviour and poor quality measurements happened in the extrusion process, etc. The experimental pre-tests include (1) investigation of the relationship between melt temperature and barrel setting temperatures (2) investigation of the relationship between melt pressure and screw speed and (3) building the relation equation between measured viscosity, melt temperature and speed for the in-line rheometer, etc.
In order to test the effectiveness of the MIMO FLC, an off-line simulation program is developed, and the closed-loop tests are performed on the extruder. The test results prove that the designed MIMO FLC can effectively control the quality of products.
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The boundary distribution charaters of Equal Channel-Angular Extrusion processed aluminiumWu, Po-Chang 13 August 2003 (has links)
none
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Specialty sorghums in direct-expansion extrusionPerez Gonzalez, Alejandro Jose 25 April 2007 (has links)
Whole-grain, high-fiber, or decorticated extrudates of excellent properties were
made from white (nonwaxy, heterowaxy, waxy) sorghums or brown tannin-sorghums.
Intact grains or prepared raw materials (cracked, cracked and sifted, decorticated) were
extruded in a high-temperature, short-time (HTST) extruder. Waxy extrudates expanded
less and were softer than those from nonwaxy or heterowaxy sorghums. Waxy
extrudates had bigger air cells and thicker cell walls. Low moisture used in this type of
extrusion and its interaction with the different amylose contents were the causes of the
differences. Whole-grain extrudates from white sorghum had similar sensory
acceptability to those from white decorticated sorghum. They had bland flavor and
appearance and texture characteristic of whole-grain products. Extrudates from tannin
sorghums were reddish brown due to their high levels of phytochemicals. The more
expanded, softer products from whole-grain tannin sorghum were obtained when the
grain was cracked and sifted. Decreased expansion was caused by higher levels of fiber
and greater particle sizes (as in the extruded intact grain), and by reduced particle sizes
(as in the cracked non-sifted grain). Expansion was correlated to smaller air cells with
smooth walls. A simple enzymatic method was developed that isolates the 'gritty'
particles from whole-grain/high-fiber extrudates, which closely correlated with
expansion. Gritty particles were fiber (bran) plus undegraded starchy material. Whole
grain/high fiber extrudates from white and tannin sorghums are an excellent option for
food processors because of their excellent taste, appearance and texture.
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Optimized upper bound analysis of polymer coated metal rod extrusion through conical dieShah, Ritesh Lalit 17 September 2007 (has links)
Extrusion is a metal forming process used extensively in industry to produce different
structural, mechanical, electrical, architectural, automotive and aerospace application
parts. Currently after extrusion, the rod is subjected to environmental wear due to long
storage time and hence requires an additional cleaning process before further use. This
cleaning process can be eliminated by extruding a polymer coated metal rod workpiece
such that the polymer coating is sustained on the final product after the extrusion
process.
In the present research study a new upper bound analytical model is developed to predict
the forces required to conduct extrusion of a polymer coated metal rod successfully. The
search for the lower upper bound power functional is modeled as a non linear
optimization problem. Optimizing the functional also determines the set of constraints
defining the shape of rigid plastic deformation boundaries and the final coating
thickness. Also an upper bound analytical model was developed to predict forces for
failure of the polymer coating during the extrusion. Both the analytical models for successful and failed extrusion are compared to obtain critical die angle which can
provide tooling and process design guidelines. Finite element analysis simulations were
modeled using commercially available software package, ABAQUS. Predictions of FEA
simulations were in good agreement with published results and with the predictions of
analytical model developed in this study.
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Microstructure and Properties of AZ31 Magnesium Alloy Processed by Equal Channel Angular Extrusion.Ding, Shi-xuan 17 September 2008 (has links)
none
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Study on Hot Extrusion Processes of Magnesium Alloy Tubes and SheetsTu, Shih-Ming 05 August 2009 (has links)
This study involves analyses and experiments of magnesium¡¦s hot extrusion of thin sheets and tubes. At first, hot compression tests are conducted to obtain the magnesium¡¦s plastic flow stresses in high tempearatures, which will be used in the finite element analysis. In the FE simulations of thin sheet extrusion, the flow pattern of the magnesium billet within the die, the temperature history at die exit and the elastic deformation of the die is analyzed. Sound and good thin sheets are obtained by appropriate die design, initial billet temperature and extrusion velocity¡¦s control. The goal of constant temperature extrusion is expected to achieved by controlling the extrusion velocity which will influences the billet temperature at die exit. In FE simulations of thin tube extrusion, the flow pattern of the magnesium billet within the port-holes, welding chamber and die bearing is analyzed. The elastic deformation of the die is dicussed. Extrusion of sound thin tubes is achieved by appropriate extrusion conditions. Finally, hot extrusion experiments are conducted and the experimental values of the extrusion load and dimensions of the products are compared with the analytical values to verify the validity of the analytical models.
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