• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2002.02a
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• pp.225-230
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• 2002

As in most metal forming processes, die and lubrication are of vital importance in hydrostatic extrusion. An efficient die design and lubrication system selection reduce the pressure required for a given reduction ratio by lowering friction at the billet-die interface. In contrast to the conventional macroscopic extrusion, fine-wire fabrication requires higher extrusion pressure and effect of friction is much more significant. Forming fine Au, Ag, and Cu wire with hydrostatic extrusion process in cold condition, the effect of extrusion die angle, lubrication and billet's initial diameter was studied.

• Journal of Biosystems Engineering
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• v.35 no.6
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• pp.408-412
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• 2010

Rheological properties of cereals such as rye are great important for the design of die for extrusion and the development of models for extrusion process. Therefore, this study was carried out to analyze the rheological properties according to moisture content of rye flour and extrusion temperature. Rheological properties of rye flour were investigated by using a capillary rheometer for moisture content of three levels (30, 35, 40%) and extrusion temperature of three levels (120, 130, $140^{\circ}C$). Determination coefficients for the relationship between apparent shear stress ($\tau_{ap}$) and apparent shear velocity ($\gamma_{ap}$) were relatively high in the range of 0.973 ~ 0.997 under each extrusion condition. The values of consistency index (K) was decreased with increasing moisture content and extrusion temperature. However, the value of flow behavior index (n) presented the highest value at moisture content of 35%, but it was not affected by extrusion temperature.

• Food Science and Biotechnology
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• v.16 no.5
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• pp.783-788
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• 2007

An advantage to the extrusion of raw potatoes is a reduction in the energy input required to process potato products; however, the effects of extrusion on the properties of raw potato have not been studied. The purposes of this study were to develop a workable extrusion process for raw potato and to study the effects of extrusion conditions on the pasting properties of extruded potato products. The peak viscosity, final viscosity, pasting temperature, water solubility index, and water absorption index of pressed and pressed-dried potato extrudates decreased as die exit temperature increased, whereas they did not change as screw speed increased. The peak viscosity, final viscosity, and water solubility of steam-cooked potato products decreased with extrusion processing; however, they did not change with increasing die exit temperature and screw speed. Potato products with different degrees of depolymerization of extruded potato starch, depending on die exit temperature, were produced from raw potatoes.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.03b
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• pp.125-130
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• 1999

In order to reduce the forming load of backward extrusion to a feasible level a new backward extrusion processes are proposed. In these process the shape of punch and die for conventional backward extrusion are change to open backward extrusion. To analyse the process numerical simulations by the finite element method has been performed, This simulation gave good results concerning the prediction of the forming load material flow and the corresponding shape of forged products, . These predictions set the limits of the preform shape and forming load depending on the punch and die geometry. The results show that the forming load is reduced significantly when the conventional backward extrusion change to open backward extrusion.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.11
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• pp.116-121
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• 1999

Since the material flow near the die part in CONFORM (Continuous Extrusion Forming) process is similar to that of side-extrusion, the side-extrusion model of tube shaped aluminum profiles was studied for the die design in CONFORM process. In this paper, the effects of process parameters in the side -extrusion through a two-hole die face, such as material flow, height and thickness of the tube, velocities of punch and lengths of bearing land were investigated using UBET program and DEFORM commercial FEM code. The optimum lengths of the bearing lands and punch velocities for obtaining the straight shape products required were determined.

• Korean journal of food and cookery science
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• v.32 no.4
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• pp.449-457
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• 2016

Purpose: The study was conducted to analyze the change in quality characteristics of Ddukguk Garaedduk and Ddukgukdduk by the frequency of extruding rice dough. Methods: Ddukguk Garaedduk samples were made by extruding and shaping rice flour dough 2, 3, and 4 times; while Ddukgukdduk samples were made by drying the Ddukguk Garaedduk at room temperature for 48 hours and slicing them in slices of 0.3 cm thickness. Results: Significant differences were not found in water content by the extrusion frequency for Ddukguk Garaedduk and Ddukgukdduk. The adhesiveness and springiness of Ddukguk Garaedduk with a 4 times extrusion were significantly higher than those of Ddukguk Garaedduk with a 2 times extrusion. Ddukgukdduk with a 4 times extrusion generated finer cells and a more even distribution of cells than the other samples, as observed by scanning electron microscopy. Upon boiling, significantly more water was absorbed in Ddukgukdduk of a 2 times extrusion than in that of a 4 times extrusion. Hardness and adhesiveness scores of the cooked Ddukgukdduk were the highest, and springiness was the lowest in the sample with the 4 times extrusion. Conclusion: The extrusion of rice dough makes the structure of Ddukguk Garaedduk finer and more even, which results in the increased adhesiveness of Ddukguk Garaedduk. When cooking Ddukguk, Ddukgukdduk that has been extruded more absorbs less water and dissolves less solids, which maintains the chewiness and structure of cooked Ddukgukdduk.

• Transactions of Materials Processing
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• v.8 no.6
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• pp.604-611
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• 1999

This paper is concerned with the family of parts that generally feature a central hub with radial protrusions. As opposed to conventional forward and backward extrusion, in which the material flows in a direction parallel to that of the punch or die motion, the material flows perpendicular to the punch motion in radial extrusion. Three variants of radial extrusion of a collar or flange are investigated. Case I involves forcing a cylindrical billet against a flat die, Case II involves deformation against a stationary punch recessed in the lower die, and Case III involves both the upper and lower punches moving together toward the center of the billet. Extensive simulational work is performed with each case to see the process conditions in terms of forging load, balanced and symmetrical flow in the flange. Also, the effect of the gap size and die corner radii to the material flow are investigated. In this study, the forming characteristics of radial extrusion will be considered by comparing the forces, shapes etc. The design factors during radial extrusion are investigated by the rigid-plastic FEM simulation.

• Elastomers and Composites
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• v.30 no.3
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• pp.235-246
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• 1995

When an O-ring is installed in a high fluid pressure device, a section of the O-ring is extruded into the piston-cylinder clearance gap. Any tendency towards extrusion will induce wear in dynamic applications, leading to premature failure of the seal. In this study, the mechanism of initial extrusion of the O-ring was studied, 1.e., how much amount of the O-ring will be extruded into the clearance gap at a certain pressure. The relationship between extrusion depth and a clearance gap or fluid pressure were studied by finite element analysis (FEA). After that, Salita's experimental data were analyzed. The result is that Initial extrusion depth for an O-ring into a clearance gap was 1.11 times the product of dimensionless pressure difference $(p-p_1)/E$ and clearance gap c. The required pressure $p_1$ for zero extrusion depth was found to decrease logarithmically with increasing clearance gap.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.05a
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• pp.5-8
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• 1999

The present work is concerned with three-dimensional finite element analysis of the hollow section extrusion process using a porthole die. For economic computation, mismatching refinement, an efficient domain decomposition method with different mesh density for each subdomain, is implemented. The proposed method improves the computational efficiency significantly, especially fur the three-dimensional analysis of extrusion problems. As a numerical example, extrusion of the underframe part of a railroad vehicle are analyzed. For three-dimensional mesh generation of a complicated shape with hexahedral elements, a modified grid-based approach with the surface element layer is utilized. The analysis results are then successfully reflected on the industrial porthole die design.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.797-801
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• 2003

The mechanical properties such as shear strength and the hardness of milli-size products that manufactured for various process parameters by forward extrusion using square dies are investigated. Shear strength test is implemented for the observation of relation between vickers hardness and shear strength in the interface of head and shaft part of a stepped pin. When the extrusion ratios of pure aluminum and pure copper billets increase, the hardness on both the surface and the center line of a pin also increase, especially the hardness on the surface is shown to be a little higher than on the center. The existence of knock-out pad in extrusion die caused hardness increase in the interface of a extruded pin. As compared shear strength with hardness of a pin, the approximated linear relations are suggested in this study.