• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.10
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• pp.2211-2218
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• 2002

In this study, an optimal design study has been made to determine dimensions of die and multi stress rings for extrusion process. For this purpose, a thermo-rigid-viscoplastic finite element program, CAMPform, was used fur forming analysis of extrusion process and a developed elastic finite element program fur elastic stress analysis of the die set including stress rings. And an optimization program, DOT, was employed for the optimization analysis. From this investigation, it was found out that the amount of shrink fitting incurred by the order of assembly of the die set should be taken into account for optimization when the multi stress rings are used in practice. In addition, it is construed that the proposed design method can be beneficial fur improving the tool life of cold extrusion die set.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.6
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• pp.76-81
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• 2021

A plastic noise barrier is a structure installed to minimize noise, and it is composed of the main plate, sound-absorbing plate, and sound-absorbing material. Plastic noise barrier structures have several advantages compared to other products, such as light weight, anticorrosion, durability, easy assembly, rapid construction, and low costs. In this study, the main and sound-absorbing plates were manufactured through extrusion molding, and the sound-absorbing plate was finished with a press to improve the conventional injection molding. Extrusion molding dies and punch dies were designed, and a profile extrusion-molding system was developed. Thus, inexpensive and efficient sound-absorbing and main plates can be produced, and the noise barrier structure can be assembled rapidly. Additionally, a noise barrier structure with extended service life and excellent quality can be constructed by creating uniform free space to accommodate increased temperatures after assembly and installation.

• Korean Journal of Food Science and Technology
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• v.22 no.6
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• pp.651-658
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• 1990

Starch phosphates were prepared by dry heating, gelatinizing method and extrusion process using sodium tripolyphosphote (STPP) as a substitution reagent and their physicochemical properities were compared. In the preparation of starch phosphate by dry heating method(DSP), the effect of reaction temperature was the most significant to the DS(Degree of substitution). In the phosphorylation reaction with gelatinized starch(GSP), the substitution ratio was increased with increasing the reaction temperature, but the increase was insignificant above $85^{\circ}C$. By extrusion with the corn starch containing 2.0% STPP at various moisture contents of 20, 25 and 30%, the DS values of extrudate(WESP) were within the range of between 0.0066 and 0.0083. The starch phosphate(DSP) products showed lowering the gelatinization temperature, increasing the clarity of the starch paste. However, WESP showed higher gelatinization temperature than that of raw starch. The starch phosphate prepared by extrusion process showed lower apparent viscosity of paste than that of the DSP at same condition. All of starch phosphates showed reducing the tendency of the paste retrogradation.

• Transactions of Materials Processing
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• v.31 no.6
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• pp.344-350
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• 2022

Extruded Mg-Bi binary alloys are known to have an undesirable bimodal grain structure containing a large amount of coarse unrecrystallized grains. Accordingly, to improve the microstructural homogeneity of extruded Mg-Bi alloys, it is necessary to promote the dynamic recrystallization (DRX) behavior during hot extrusion. An effective way to promote DRX is an increase in nucleation sites for DRX through a pre-deformation process before extrusion, such as cold pre-forging and hot pre-compression. However, the application of these pre-deformation processes increases the cost of final extruded Mg products because of an increase in energy consumption and decrease in productivity. Therefore, a low-cost new continuous process with high productivity is required to improve the microstructural homogeneity and mechanical properties of extruded Mg alloys without a drastic increase in the entire process cost. This study proposes a new extrusion method using an extrusion billet with a truncated cone shape (i.e., tapered billet) instead of a conventional extrusion billet with a cylindrical shape. When the hot extrusion of a Mg-5Bi alloy is conducted using the tapered billet, the DRX behavior during extrusion is considerably promoted. The DRX fraction and average grain size of the extruded alloy significantly increase and decrease from 65% to 91% and from 225 ㎛ to 49 ㎛, respectively. Consequently, the extruded Mg-5Bi alloy fabricated using the tapered billet has a finer homogeneous grain structure and higher tensile elongation than the extruded counterpart fabricated using the cylindrical billet.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.10a
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• pp.42-45
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• 2008

Recently, aluminum is widely used to reduce the vehicle weight. Aluminum curved extruded products are used for the design of automotive frame parts. This study focuses on the determination of process condition fur automotive bumper beam with various curvatures. In this study, a curvature prediction model has been proposed considering the geometric relationship and the characteristic of the curvature extrusion equipment. Using the proposed model and FE analysis, the appropriated process condition was determined to produce the bumper beam. Finally, curvature extrusion experiment was carried out to verify the effectiveness of the proposed curvature prediction model and the process condition.

• Transactions of Materials Processing
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• v.10 no.4
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• pp.302-310
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• 2001

The twisting and extrusion process of the product with involute helical fin from the round billet is developed by the upper bound analysis. The twisting of extruded product is caused by the twisted inclined die surface connecting the die enterance section and the die exit section linearly. In the analysis, the internal shear surface is defined as the curved twisted plane from the twisting of die surface and the shear work is calculated by the consumption of shear energy. The increase rate of angular velocity is determined by the minimization of plastic work. The angular velocity of die exit can be controlled by the land length and the length of inclined die. The alular velocity assums to be increased linearly by the axial distance from the die enterance to the die exit. The results of the analysis show that the angular velocity of the extruded product increases with the die twisting angle, the reduction of area, and decreases with the die length, the friction constant.

• Transactions of Materials Processing
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• v.21 no.3
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• pp.164-171
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• 2012

This paper focuses on the development of a new SPD (severe plastic deformation) process named HCAE (half channel angular extrusion). HCAE technology is based on principled similar to ECAE, but imposes a larger amount and more effective plastic deformation on materials. The amount of shear deformation can be altered by varying the process parameters. Finite element analyses of HCAE were conducted in order to investigate the characteristics of deformation during HCAE and the simulated results show that the predicted value of imposed plastic strain in a single pass reaches 2.5.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.2
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• pp.144-150
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• 2000

In this paper, the formation of a corner cavity in the final stage of axisymmetric backward extrusion process is studied by means of upper bound analysis using kinematically admissible velocity. The quantitative relationships between corner cavity formation and process parameters are studied. And analytical results are compared with those of experiment to which plasticine is used. It is found that the analytical results agree well with experimental one. In addition, to restrict the formation of a corner cavity, driven container is applied to backward extrusion and the results are compared with those of FEM. The critical thickness of the bottom of the billet decreases with increase in reduction of area, and increases with decrease in friction. To prevent the formation of corner cavity, the concept of moving container was applied. Throughout this process, the occurrence of a corner cavity is delayed and forming limit area is enlarged.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2000.10a
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• pp.70-73
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• 2000

A finite element analysis model is suggested for analysis of forming process of milli structure whose size is from a few hundreds ${\mu}m$ to a few mm. In this paper, finite element formulation which assemble crystal plasticity theory considering texture development with damage mechanics is developed, since orientation development and growth of micro voids became the primary factors for deformation aspects in large deformation of milli structure. Applying to, extremely, extrusion process of single crystal and extrusion/drawing process of polycrystal milli-size bar, extrusion force, preferred orientation, and damage evolution are examined to understand the characteristics of deformation of milii-size bar.

• Transactions of Materials Processing
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• v.7 no.4
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• pp.364-374
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• 1998

It is the objective of this study to analyze the effect of various process variables on the quality of extruded product and extrusion force for semi-solid extrusion of Al2024 with solid phase structure of globular type by the finite element method. Process variables are initial solid fraction, ram speed, semi-angle of die, and reduction in area. The results of experiment are compared with those of simulation in order to verify the usefulness of the developed finite element program. The flow and deformation of semi-solid alloy are analyzed by coupling by coupling the deformation of porous skeleton and the flow of liquid phase. It is also assumed that initial solid fraction is homogeneous.