• Journal of the Korean Society of Manufacturing Process Engineers
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• v.3 no.1
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• pp.66-71
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• 2004

Magnesium alloys have been widely used for many structural components of automobiles and aircraft because of high specific strength and good cast-ability in spite of hexagonal closed-packed crystal structure of pure magnesium. In this study, it is studied about the forming characteristics of press forging of AZ31 magnesium alloy by MSC/MARC in case of material having one boss and MSC/Supeiforge in case of material having multi-boss with heat transfer analysis during deformation at elevated temperature. For these results it is simulated about temperature distribution, strain distribution, and stress distribution of AZ31 Magnesium alloy. During the press forging, foot regions of bosses showed greater temperature rise than other areas of AZ31 sheet. Finally the plastic strain of AZ31 sheet did not remarkably vary with increasing temperature from 373 to 473K, while it significantly increased as the forming temperature increased from 473 to 573K, which is related with the change in micro-structures, such as dynamic re-crystallization occurring during the deformation process.

• Journal of the Korean Wood Science and Technology
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• v.23 no.4
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• pp.74-84
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• 1995

Eight types of thin composite panels were manufactured by press-lam and mat-forming process applied to optimum manufacturing condition, studied in former first research by author (1995). They were tested and compared with control boards on dimensional stability, internal bond strength, tensile strength, Screw withdrawal strength, and bending properties. These thin composite panels manufactured by mat-forming process were generally superior to those by press-lam in dimensional stability and mechanical properties. In the dimensional stability and mechanical properties of thin composite panels manufactured by mat-forming process, the thin composite panels (A and E type) composed of particle or sawdust core and veneer face with polyethylene film, were as good as those of common plywood (control board). Internal bond strength showed highest value in the thin composite panel(D type) which composed of particle core and polypropylene screen face with polyethylene film. The thin composite panels(G and H type) composed of sawdust or particle core and polypropylene screen face with polyethylene film by press-lam and mat-forming process, showed most highest value in dimensional stability and water absorption.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.7
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• pp.55-63
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• 2008

Fine blanking is a process of press shearing which makes it possible to produce the thick sheet metal of the finished surface and the close dimensional accuracy over the whole material thickness in the single blanking operation. In this paper, a plate holder of automotive seat recliner is manufactured by FCF(Flow Control Forming) method using the conventional mechanical press instead of the fine blanking press. Main processes for manufacturing of the plate holder by FCF method are embossing, half blanking and trimming processes. Optimal clearance, stripper force and counter force to increase the dimensional accuracy of the plate holder have been investigated by FE-analysis. As a result of FE-analysis, the clearance for both embossing and half blanking processes was -2%t and the forces of stripper and counter were 25ton and 15ton, respectively. After manufacturing the plate holder by FCF method, the measured dimensional characteristics have been compared with the required specifications as the final product. Although the dimensional accuracy of the plate holder manufactured by FCF method was a little inferior to that by fine blanking process, it was satisfactory in a general sense.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.23 no.5
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• pp.413-420
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• 2014

Although the transfer forming process has various advantages, it is also inefficient for the use of multiple press machines, especially for small part sizes. In this study, a new forming process was proposed to use multiple tandem dies in a single press machine. A rotary transfer forming device was developed to combine the advantages of the progressive and transfer forming process. In this study, a detailed forming process using this device was analyzed, and the device was designed to perform four series of tandem forming processes in a single press. In order to analyze the feasibility of this forming process, simple forming dies were made. As a result, the position accuracy was 4 arcsec, and the forming speed reached up to 20 strokes per minute. It is thought that this rotary transfer forming device can help to save initial setup costs through the more efficient use of space in a press machine.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.1
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• pp.63-72
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• 2011

In recent years, hot-stamped components are more increasingly used in the automotive industry in order to reduce weight and to improve the strength of vehicles. In hot stamping process, blank is hot formed and press hardened in a tool. However, in hot stamping without cooling channel, temperature of the tool increases gradually in mass production thus cannot meet the critical cooling rate to obtain high strength over 1500MPa. Warpage occurs in the hot stamped component due to non-uniform stress state caused by unbalanced cooling. Therefore, tools should be uniformly as well as rapidly cooled down by the coolant which flows through cooling channel. In this paper, optimal design method of cooling channel to obtain uniform and high strength of the component is proposed. Optimized cooling channel is applied to the hot press V-bending process. As a result of measuring strength, hardness and microstructure of the hot formed parts, it is known that the design methodology of cooling channel is effective to the hot stamping process.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.6 no.6
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• pp.560-565
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• 2005

This paper deals with the development of manually operated die used for the manufacture of octagonal boxes into two sets of automated die. In particular, theoctagonal boxes are used fur the switch boxes intended fur the cable conduit of buildings or f3r wiring connection. Manufacturing these boxes requires forming the materials using the primary press before they undergo 2nd through 6th processing by the press machine including the four sides of the octagonal outlet box and bending. Such complicated process hikes up labor cost, slows down production, and results in defect rate of $10\%$ or higher; hence the overall rise in manufacturing cost. Moreover, workers avoid this type of work due to the roar and vibration coming from the press and the risk of accident. To eliminate such phenomenon, a CAM die made by integrating five sets of die into one set of die and an automatic conveyor system were developed. As a result, unmanned work was realized with only two units of press and two sets of die; thus solving the problem of work being avoided and saving on manufacturing cost.

• Journal of the Korean Society for Heat Treatment
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• v.33 no.3
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• pp.99-106
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• 2020

Selective laser melting (SLM) is an additive manufacturing process by melting metallic powders and stacking into layers, and can product complex shapes or near-net-shape (NNS) that are difficult to product by conventional processes. Also, SLM process is able to raise the efficiency of production by creating a streamlined manufacturing process. For manufacturing in SLM process using Ti-6Al-4V powder, analysis of microstructural evolution and evaluation of mechanical properties are essential because of rapid melting and solidification process of powders according to high laser power and rapid scan speed. In addition, it requires a post-processing because the soundness and mechanical properties are degraded by defects such as pore, un-melted powder, lack-of-fusion, etc. In this study, hot isostatic press (HIP) was conducted as a post-processing on SLM-printed Ti-6Al-4V alloy. Microstructure of post-processed Ti-6Al-4V alloy was compared to as-built Ti-6Al-4V, and the evolution of quasi-static (Vickers hardness, room temperature tensile characteristic) and dynamic (high-cycle fatigue characteristic) mechanical properties were analyzed.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2005.09a
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• pp.155-159
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• 2005

High speed presses with high resolution in semiconductor lead frame manufacturing process are needed . But high speed operation accompanies mechanical vibration. therefore optimized kinematic structure to minimize vibration is required for a high speed press. And the growing competition in the industry asks a press with low cost, high speed, high resolution, and high pressing force, For this purpose a high speed press was modeled with 3D CAD solid modeling system and dynamic analysis were performed with CAE S/W for multibody dynamic analysis, Through these analyses a motor appropriate to a high speed press was selected and link structure for feeding system of the press was modified to reduce vibration. To perform this analysis working Model which is 2D kinematics and dynamic analysis software was used.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.3
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• pp.130-134
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• 2016

Due to the need for advanced technologies in the automotive industry, the demand for lighter and safer vehicles has increased. Even though various nonferrous metals, like Aluminum, Magnesium and also Carbon Fiber Reinforced Plastic (CFRP), have been implemented in the automotive industry, a lot of technical research and development is still focused on ferrous metals. In particular, the market volume of High Strength Steel (HSS) parts and Ultra High Strength Steel (UHSS) by hot press forming parts has expanded significantly in all countries' automotive industries. A new tool steel, High Thermal-Conductivity Tool Steel (HTCS), for stamping punches and dies has been developed and introduced by Rovalma Company (Spain), and it is able to support better productivity and quality during hot press forming. The HTCS punches and dies could help to reduce cycle time due to their high thermal conductivity, one of the major factors in hot press forming operation. In this study, test dies were manufactured in order to verify the high thermal conductivity of HTCS material compared to SKD6. In addition, thermal deformation was inspected after the heating and cooling process of hot press forming. After heating and cooling, the test dies were measured by a 3D scanner and compared with the original geometry. The results showed that the thermal deformation and distortion were very small even though the cooling time was reduced by 2 seconds.

• Research in Community and Public Health Nursing
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• v.30 no.3
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• pp.336-344
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• 2019

Purpose: This study tries to examine the effects of hand moxibustion and press pellet by applying them to male manufacturing workers with low back pain, and use them to develop nursing interventions for workers. Methods: The data were collected from August to October, 2018, and the subjects were 60 men, processed by using SPSS/WIN 21.0 to perform homogeneity test with $x^2$-, t-, and hypothesis tests with repeated measures, ANOVA and $Scheff{\acute{e}}$ test. Results: Hypothesis 1 that "the experimental group provided with hand moxibustion and hand press pellet would give lower scores for low back pain than the control group" was supported (F=78.71, p<.001). Hypothesis 2 that "the experimental group provided with hand moxibustion and hand press pellet would have a wider range of motion than the control group" was also supported (F=17.44, p<.001). Hypothesis 3 that "the experimental group provided with hand moxibustion and hand press pellet would give lower scores for depression than the control group," again, was supported (F=16.95, p<.001). Conclusion: Hand moxibustion and hand press pellet are effective in relieving low back pain for male workers, in increasing the range of motion, and in decreasing depression.