• Transactions of the Korean Society of Machine Tool Engineers
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• v.18 no.2
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• pp.194-200
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• 2009

The extruder type is classified as screw type and non-screw type in terms of the extrusion method. The screw type extruder, which is the most frequently used, is classified as the single screw extruder and the multi-screw extruder. They are classified as vertical type and horizontal type in terms of structure; and those for compounding and for forming in terms of function. The single screw extruder is a universal extruder, most of which is suitable for the extrusion forming of thermoplastic resin. The multi-screw(two-screw, three-screw and four-screw) extruder can increase the extrusion power using the engagement of the screw flank. The single screw extruder does not have a good mixing ratio of the raw material and stable extrusion power, while it has low construction cost and operation cost. In this study, the single screw extruder, which has many weak points compared with the multi-screw extruder, was studied. There have been many studies on the single screw extruder, and they led to its significant development. The existing study method, however, had complex analysis processes and required much time. In this study, the CFD was applied to the performance test and analysis of the extruder, and the optimal design condition of the extrusion power for the screw and die of the single screw extruder was found by comparing the analysis results with the actual performance measurement of the single screw extruder.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.706-709
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• 1997

Extruders are the heart of the polymer processing industry. The single most important mechanical element of a screw extruder is the screw. The proper design of the geometriy of the extruder screw is of crucial importance to the proper functioning of the extruder. If material transport instabilities occur as a result of improper screw geometry, even the most sophisticated computerized control system cannot solve the problem. For this purpose, characteristics design on helix angle of the extruder screw. This paper presents strength of the screw flight, optimum helix angle versus dimensionless down channel pressure gradient, optimum helix angle versus the power law index in simultaneous optimization, volumetric efficiency versus helix angle at various number of flights and power consumption versus helix angle in the barrel of screw extruder.

• Korean Journal of Food Science and Technology
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• v.20 no.3
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• pp.303-309
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• 1988

The heat generation at the start-up period of an autogeneous single screw extruder was determined with various feed materials, die structure and operational conditions. The highest heat generation rate was observed with defatted soybean meal, while the lowest value was obtained with rice flour, and wheat and barley flour showed the intermediate rate. As the moisture content of the flour decreased and the screw speed increased, the electric power requirement and heat generation rate increased. The temperature at compression section increased with the decrease in the particle size. The same effect was also observed as breaker plate was installed. The optimum operation was established as the temperature profile was maintained in decreasing order of metering section, die and compression section.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.1 s.232
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• pp.145-155
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• 2005

In this study, a finite element method program code which can be accomodate boundary conditions on the complex surfaces has been developed to simulate polymer extruder processes. The analysis method includes the fractional 4-step method for efficient computation time and compact usage of memory storage to solve the velocities and the pressure values from the Navier-Stokes equation. By using the developed program which was verified with simple Poiseuille flow mixture phenomena in single-and twin-screw extruder are analyzed. It is concluded that the proposed method resulte Poiseuille Poiseuille d in fair agreement with the exact solution of simple flow and the back flow near the entrance happens in single-screw model. It is identified that the location and values of maximum pressure in the twin screw extruder model. It is expected that the Velocity field found can be used to predict the degree of mixture in the extruder barrel.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.12
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• pp.1615-1623
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• 1997

Numerical study on the chaotic stirring of the screw extruder model proposed has been performed. The velocity field was used in obtaining the trajectories of passive particles for studying the stirring effect of the screw extruder. Two nonlinear dynamical tools, that are Poincare sections and Lyapunov exponents, were used in analysing the stirring effect. The Poincare sections and the Lyapunov exponents show that the stirring effect is most satisfactory, when n(the number of flights in a section) is 1, for the case a (aspect ratio ; flight height divided by the spacing between flights) being O.1. It is also required to set n=3, or 5 at a= 0.2, 0.3 for a uniform stirring.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.337-342
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• 2001

A numerical study of three-dimensional fluid flow and heat transfer in the metering section of a single screw extruder has been performed. The mathematical model for the screw channel is simplified by unwound channel and fixing the coordinate system to the screw. The pressure boundary and the prescribed mass flow rate conditions are imposed on the inlet and outlet, respectively. The commercial code STAR-CD based on the finite volume method is used to obtain the results of the present work. The computation of the reverse flow, which cannot be computed by the marching-type 3-D model, is performed in the present study.

• Korea-Australia Rheology Journal
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• v.18 no.3
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• pp.143-151
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• 2006

We analyzed the non-Newtonian and non-isothermal flow in a single screw extruder system and investigated the mixing performance with respect to the screw speed and the screw pitch. The viscosity of polymer melt was described with Carreau-Yasuda model. The mixing performance was computed numerically by tracking the motions of particles in the screw element system. The extent of mixing was characterized in terms of the deformation rate, the residence time distribution, and the strain. The results revealed that the high screw speed reduces the residence time but increases the deformation rate while the small screw pitch increases the residence time. It is concluded that the high screw speed increases the dispersive mixing performance and the small screw pitch increases the distributive mixing performance.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.246-251
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• 2000

In the present study, the analysis on heat and fluid flow in the single screw extruder is carried out by simultaneously considering the metering section and the die. The finite difference method and the finite volume method are applied to the metering section and the die, respectively. The zonal method is used to couple the metering section and the die. To investigate the effect of die on the characteristics of heat and fluid flow in the single screw extruder, the pressure back flow is included in the analysis. The screw-tip rotation is also considered by employing the quasi 3-dimensional die model. The present results are compared with the numerical and experimental data available in the literatures.

• Korean Journal of Food Science and Technology
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• v.15 no.4
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• pp.392-398
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• 1983

A pilot single-screw food extruder was constructed, and its mechanical properties and product characteristics were investigated by using corn grits. The screw rotational speed was varied and the changes in temperature profile of the barrel for the start-up period of operation were measured. The rate of heat generation for the start-up period was affected by the screw speed and feed rate. The screw speed resulted in a great influence on the estimated dough viscosity. The changes in the dough viscosity could indicate the on-set of termoplastic reaction in the barrel. The expansion ratio during the start-up period mainly depended on the barrel temperature and the degree of thermoplastic reaction in the barrel. The barrel temperatures for the gelatinization and burning of corn grits depended on the screw speed as well as the feed rate.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.824-828
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• 2002

Twin screw extruders are the heart of the polymer processing industry. The single most important mechanical element of a screw extruder is the screw. The proper design of the geometry of the excluder screw is of crucial importance to the proper functioning of the extruder. If material transport instabilities occur as a result of improper screw geometry, even the most sophisticated computerized control system cannot solve the problem. For this purpose, Tool shape design for the screw flights cutting in twin screw extruder.