Jung-Bin Lee ¹, Jong-Rok Ahn ², Doo-Seuk Choi ³, Key-sun Kim ³

Affiliations
1 Department of Mechanical Engineering, Cheonandaero Seobuk-Gu Cheonan Chungnam, 31080, Korea
2 Industrial Machinery Manufacturing, Sinhyu-gil Eumbong-myeon Asan Chungnam, 31408, Korea
3 Kongju National University, Division of Automotive & Mechanical Engineering, Cheonandaero Seobuk-GuCheonan Chungnam, 31080, Korea

Abstract

Objectives: Recent trends show an increase in driving by the elderly and most of them drive with a poor posture. In this study, not only the tests for body pressure but also the tests to identify characteristics of the seat itself were conducted. Methods/Statistical Analysis: Static load tests were conducted first to derive the seat-inherent characteristics such as deflection and hardness, etc. of the seat cushion as a function of loads for the automotive seat, and measurement tests for body pressure were conducted to secure body pressure data of the elderly. Combining the above two test results, final hardness values were obtained through which seat cushion pattern models having 8-hardness distributions could be derived. Findings: As a result, curves and functional equation for the two variables were derived through deflection as a function of measured loads. Also, hardness values at each point of the cushion could be found from the slopes of the curves mentioned, with the appearance of the phenomenon where the slope showed a steep increase in a particular region. This was affirmed to have occurred due to a difference in thicknesses of the cushion. Secondly, concentrated regions of body pressure per subject were affirmed and analyzed in the body pressure tests. By combining two test results, a total of 11 seat cushion pattern models could be derived, of which pattern analyses were conducted for 3 types observed with many personnel. Improvements/Applications: When the cushions are produced on the basis of the above pattern, it is considered possible to more ideally distribute the weight and to improve comfort upon seating compared with the commercial cushions.

Keywords

Body Pressure, Deflection, Hardness, Pattern, Seat Cushion.

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Kwang-Soo Lee ¹, Key-Sun Kim ²

Affiliations
1 Division of Mechanical Engineering, Graduate School, Kongju University, KP
2 Department of Mechanical and Automotive Engineering, Kongju University, KP

Abstract

Background/Objectives: Recently, problems of noise produced in the vehicle body are emerging. The apparatus for discharging exhaust gas produced after combustion should suitably absorb vibration and noise from the engine. Methods/ Statistical Analysis: The workpiece was used AISI 316. Characteristics shown under an internal pressure of 8~12MPa and a die speed of 9~235mm/sec were observed. With an assumption that all external conditions were the same, internal pressure due to forming-oil and speeds of die and punch were controlled. Meshes were generated in a total element number of 9,282. For plastic finite elements analysis, DEFORM 2D as the specialized plasticity code of US was employed. Findings: It was shown to be affected by internal pressures rather than by the speeds of the punch and die. Crease was affirmed to be produced in a stable manner from the minimum internal pressure of 10MPa. The gap between die and crease was shown to be smaller, the higher the pressure. And it was shown to be smaller as the speed was increased. Although formability is improved with an increase in the speeds of the punch and die, produced equivalent stresses were determined to be increased. The equivalent stress produced in the crease did not exhibit a large amount of variation as a function of internal pressure and die speed. However, as the center part of the bellows was approached, smaller equivalent stresses were observed, and while larger stresses were produced, the closer it was to the punch. Similar tendency was also shown for the load acting upon die. Therefore, it appears that speed of punch and acting load should be carefully considered in production of bellows. Application/Improvements: Characteristics of plasticity according to each case were identified, and parameters were secured allowing a comparative analysis with experimental data through future experiments.

Keywords

Bellows, Finite Elements Analysis (FEA), Forming-Oil Pressure, Hydroforming, Plastic, Punch-Speed.

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Key-Sun Kim ¹, Ok-Hwan Kim ¹, Bum-Seok Oh ¹, Chung-Sik Shin ²

Affiliations
1 Department of Mechanical and Automotive Engineering, Kongju University, KP
2 Division of Mechanical Engineering, Graduate School, Kongju University, KP

Abstract

Background/Objectives: A representative tool end mill, and predictive studies on tool wear and tool life are in urgent need since the number of products requiring high-precision processing has being increasing recently. Method/Statistical Analysis: The workpiece had a size of 20mm in length, 20mm in width, and 5mm in thickness. For the tool with the outside diameter of 8mm, the radial rake angle of 5°, and the helix angle of 20°. Processing involved oblique processing at an angle of 5° so that the depth was increased as the transfer progressed. Revolution of the tool was 600RPM with the feed-rate being set at 100mm/min. Findings: Upon initial processing, plastic deformation can be seen to occur in a center part of the end mill also, as the depth was increased while almost no initial plasticity occurred in the center part. The maximum temperature occurs at the blade tip of tool edge part that was cut the deepest, and a high temperature of about 1334.5° C was produced. Therefore, work hardening is expected to occur upon processing due to such high temperature. After the formation of chips by processing flow, rapid cooling may be observed. While similar cutting forces for all of x, y, and z axes are acting initially, those for the x-axis and y-axis can be seen to be drastically increased in a vertical direction up to about 18kN after rotation by about 900°, despite the fact that almost no cutting force is applied. The reason is considered to be application of severe vertical loads so as to act as a compressive stress for the tool as the depth of the end mill is increased in oblique plane processing. Application/Improvements: Severe concentrated loads occurred at the blade tip of tool edge so that a shivering phenomenon was considered to occur. This result will be used as the basic data upon product processing.

Keywords

Cutting Analysis, End Mill, Finite Element Method (FEM), Forming, Milling Machine, Mises Stress.

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