• Title/Summary/Keyword: Gas Force

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A Study on the Optimal Design of Gas Spring for Vehicle (자동차용 GAS SPRING의 최적 설계에 관한 연구)

  • 김영범
    • Journal of the Korean Society for Precision Engineering
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    • v.15 no.11
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    • pp.39-45
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    • 1998
  • Gas springs have been widely used in motor vehicles as well as in most areas of industry. Instead of coil springs, these gas springs are easily opreated to open(extension process) or close (compression process) the doors because $N_2$ gas with high pressure and oil are charged in tube. Most of manufacturers are using the trial & error method in order to decide its specification(reaction force, damping force), which tends to waste time and money. Therefore, gas springs have been improved by properly changing the control pressure of $N_2$ Gas with its mounting location and weight to maximize its effect and to minimize its space. Although it has been researched on damping structure to minimize impact which is applied to vehicle when its back door is fully opened, the characteristics of damping structure are not known clearly. There(ore, this paper will not only clearly define the effect of important factors(open & close force)for gas springs through theoretical analysis but also provide optimum design specification through development of program to avoid traditional method of specification determination such as the trail It error method which is widely used in whole industries including automotive industry.

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A Study on the Reaction Force Characteristics of the Gas Spring for the Automotive (자동차용 가스 스프링의 반력 특성에 관한 연구)

  • Lee, Choon Tae
    • Journal of Drive and Control
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    • v.12 no.4
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    • pp.35-40
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    • 2015
  • A gas spring provides support force for lifting, positioning, lowering, and counterbalancing weights. It offers a wide range of reaction force with a flat force characteristic, simple mounting, compact size, speed controlled damping, and cushioned end motion. The most common usage is as a support on a horizontally hinged automotive tail gate. However, its versatility and ease of use has been applied in many other industrial applications ranging from office equipment to off-road vehicles. The cylinder of a gas spring is filled with compressed nitrogen gas, which is applied with equal pressure on both sides of the piston. The surface area of the rod side of the piston is smaller than the opposite side, producing a pushing force. The magnitude of the reaction force is determined by the cross-sectional area of the piston rod and the internal pressure inside the cylinder. The reaction force is influenced by many design parameters such as initial chamber volume, diameter ratio, etc. In this paper, we investigated the reaction force characteristics and carried out parameter sensitivity analysis for the design parameters of a gas spring.

A Study on the Dynamic Characteristics of the Gas Spring on the Automotive Application (차량 장착상태에서의 가스 스프링 동적 특성 연구)

  • Lee, Choon Tae
    • Journal of Drive and Control
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    • v.12 no.4
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    • pp.15-20
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    • 2015
  • Unlike a typical metal spring, a gas spring uses compressed gas contained in a cylinder and compressed by a piston to exert a force. A common application includes automobiles where gas spring are incorporated into the design of open struts that support the weight of tail gate. They are also used in furniture such as office chairs, and in medical and aerospace applications. The gas spring works by the application of pressurized gas (nitrogen) contained in a cylinder. The internal pressure of the gas spring greatly exceeds atmospheric pressure. This differential in pressure exists at any rod position and generates an outward force on the rod, making the gas spring extend. In this paper, we investigated the dynamic characteristics of a gas spring on an automotive tail gate system.

Effect of Types of Force-fields on Gas Transport Thorough Polymer Membrane (Force-field가 고분자 분리막의 기체 투과거동에 미치는 영향)

  • Lee, Ji-Su;Park, Chi Hoon
    • Membrane Journal
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    • v.29 no.1
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    • pp.37-43
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    • 2019
  • In this study, we investigated how the force-field, which is the most important factor to define atomic motion in molecular dynamics (MD), affects the motion of the polymer and gas molecules. The repeat units and the polymer structure were well simulated in all five force-fields, and the distribution of the polymer linear chain in the final polymer 3D model did not show any significant difference. However, the movement of actual gas molecules showed a very different tendency, which was also observed in COMPASS and pcff using the same functional form. Therefore, even if the same structure is used, it can be seen that the motion of the gas molecule moves under the influence of the force-field continuously over time, so that the effect is much larger than that of macromolecules such as a polymer linear chain. Accordingly, in case of using different force-fields, it is necessary to be very careful in comparison of those results.

A Study on Optimum Shape of Shield Gas Nozzle for Bead Shape Control in TIG Welding using Gas Force (Ⅰ) - Design and Performance Analysis of Venturi Nozzle - (TIG용접에서 가스력을 이용한 비드형상제어를 위한 실드가스 노즐의 최적 형상에 관한 연구 (I) - 벤투리노즐의 설계 및 성능분석 -)

  • Ham, Hyo-Sik;Seo, Ji-Seok;Choi, Yoon-Hwan;Lee, Yeon-Won;Cho, Sang-Myung
    • Journal of Welding and Joining
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    • v.29 no.3
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    • pp.51-57
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    • 2011
  • Bead shape control with gas force process has been developed to overcome the concave back bead in pipe orbital welding. However, It is impossible to make a convex back bead using the existing gas nozzle, because it has high gas-consuming and low gas force. The purpose of this paper, to develop optimum shape of nozzle which to reduce the consumption of gas, maximizing the shield gas force with low cost and high productivity coincide the Green welding. In this paper venturi-type nozzle was designed by using the Venturi meter and compared velocity, pressure, arc shape in the flat position with existing CP-nozzle. As a result, Venturi-type nozzle's maximum velocity and pressure was improved at the same flow rate. Also heat input was increased by the arc contraction in the flat position.

A Study on Optimum Shape of Shield Gas Nozzle for Bead Shape Control in TIG Welding using Gas Force (II) - Effect of Molten Metal Control by Venturi Nozzle in Overhead Position - (TIG용접에서 가스력을 이용한 비드형상제어를 위한 실드가스 노즐의 최적 형상에 관한 연구 (II) - 벤투리 노즐의 위보기 자세 용융금속제어 효과 -)

  • Ham, Hyo-Sik;Seo, Ji-Seok;Choi, Yoon-Hwan;Lee, Yeon-Won;Cho, Sang-Myung
    • Journal of Welding and Joining
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    • v.29 no.3
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    • pp.58-63
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    • 2011
  • Bead shape control with gas force process has been developed to overcome the concave back bead in pipe orbital welding. However, It is impossible to make a convex back bead using the existing gas nozzle, because it has high gas-consuming and low gas force. The purpose of this paper, to develop optimum shape of nozzle which to reduce the consumption of gas, maximizing the shield gas force with low cost and high productivity coincide the Green welding. In this paper venturi-type nozzle was compared with existing CP-type nozzle by TIG pulse welding in overhead position. As a result, CP-type occurs the wormholes in the overhead position, but the Venturi-type without the pore and formed a good bead appearance.

Research on Acceleration Mechanism of Inflight Particle and Gas Flow Effect for the Velocity Control in Vacuum Kinetic Spray Process (진공상온분사(VKS) 공정에서의 비행입자 가속 기구 및 속도제어를 위한 가스 유량 효과에 관한 연구)

  • Park, Hyungkwon;Kwon, Juhyuk;Lee, Illjoo;Lee, Changhee
    • Korean Journal of Materials Research
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    • v.24 no.2
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    • pp.98-104
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    • 2014
  • Vacuum kinetic spray(VKS) is a relatively advanced process for fabricating thin/thick and dense ceramic coatings via submicron-sized particle impact at room temperature. However, unfortunately, the particle velocity, which is an important value for investigating the deposition mechanism, has not been clarified yet. Thus, in this research, VKS average particle velocities were derived by numerical analysis method(CFD: computational fluid dynamics) connected with an experimental approach(SCM: slit cell method). When the process gas or powder particles are accelerated by a compressive force generated by gas pressure in kinetic spraying, a tensile force generated by the vacuum in the VKS system accelerates the process gas. As a result, the gas is able to reach supersonic speed even though only 0.6MPa gas pressure is used in VKS. In addition, small size powders can be accelerated up to supersonic velocity by means of the drag-force of the low pressure process gas flow. Furthermore, in this process, the increase of gas flow makes the drag-force stronger and gas distribution more homogenized in the pipe, by which the total particle average velocity becomes higher and the difference between max. and min. particle velocity decreases. Consequently, the control of particle size and gas flow rate are important factors in making the velocity of particles high enough for successful deposition in the VKS system.

Effects of gas formers of flux cored wire on spattering (FCW의 가스 발생제가 스패터링에 미치는 영향)

    • Journal of Welding and Joining
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    • v.16 no.5
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    • pp.93-99
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    • 1998
  • Effects of gas formers of MgCO$_3$, CaCO$_3$ and Li$_2$CO$_3$ on the spattering phenomena were investigated for non-shielded flux cored arc welding. Spattering phenomena were pictured using high speed camera as a speed of 3000 frames per sec. As experimental results, spattering modes were classified into 4 types. The modes were spattering by arc force, gas explosion, short circuit and pore escape. The amount of spatters by arc force was 30%, gas blowing force was 40%, short circuit 10%, pore escape was 10% and others were 10%. When Li$_2$CO$_3$ was added, the amount of spatters was largest, and it decreased in the order of CaCO$_3$ and MgCO$_3$.

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