• Title/Summary/Keyword: Mechanical parts

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A Study on the Method and Application of Shaft Repair using Directed Energy Deposition Process (직접식 에너지 용착 공정을 활용한 축 보수 방법 및 활용 사례 연구)

  • Lee, Yoon Sun;Lee, Min Kyu;Sung, Ji Hyun;Hong, Myeong Pyo;Son, Yong;An, Seouk;Jeong, Oe Cheol;Lee, Ho Jin
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.20 no.9
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    • pp.1-10
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    • 2021
  • Recently, the repair and recycling of damaged mechanical parts via metal additive manufacturing processes have been industrial points of interest. This is because the repair and recycling of damaged mechanical parts can reduce energy and resource consumption. The directed energy deposition(DED) process has various advantages such as the possibility of selective deposition, large building space, and a small heat-affected zone. Hence, it is a suitable process for repairing damaged mechanical parts. The shaft is a core component of various mechanical systems. Although there is a high demand for the repair of the shaft, it is difficult to repair with traditional welding processes because of the thermal deformation problem. The objective of this study is to propose a repair procedure for a damaged shaft using the DED process and discuss its applications. Three types of cases, including a small shaft with a damaged surface, a medium-size shaft with a worn bearing joint, and a large shaft with serious damage, were repaired using the proposed procedure. The microstructure and hardness were examined to discuss the characteristics of the repaired component. The efficiency of the repair of the damaged shaft is also discussed.

A study on the fiber orientation and mechanical characteristics of injection molded fiber-reinforced plastic for the rigidity improvement of automotive parts (자동차 부품의 강성 보강을 위한 섬유강화 플라스틱 사출성형품의 섬유 배향 및 기계적 특성에 관한 연구)

  • Eui-Chul Jeong;Yong-Dae Kim;Jeong-Won Lee;Seok-Kwan Hong;Sung-Hee Lee
    • Design & Manufacturing
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    • v.16 no.4
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    • pp.24-33
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    • 2022
  • Fiber-reinforced plastics(FRPs) have excellent specific stiffness and strength, so they are usually used as automotive parts that require high rigidity and lightweight instead of metal. However, it is difficult to predict the mechanical properties of injection molded parts due to the fiber orientation and breakage of FRPs. In this paper, the fiber orientation characteristics and mechanical properties of injection molded specimens were evaluated in order to fabricate automotive transmission side covers with FRPs and design a rib structure for improvement of their rigidity. The test molds were designed and manufactured to confirm the fiber orientation characteristics of each position of the injection molded standard plate-shaped specimens, and the tensile properties of the specimens were evaluated according to the injection molding conditions and directions of specimens. A gusset-rib structure was designed to improve the additional structural rigidity of the target products, and a proper rib structure was selected through the flexural tests of the rib-structured specimens. Based on the evaluation of fiber orientation and mechanical characteristics, the optimization analyses of gate location were performed to minimize the warpage of target products. Also, the deformation analyses against the internal pressure of target product were performed to confirm the rigidity improvement by gusset-rib structure. As a result, it could be confirmed that the deformation was reduced by 27~37% compared to the previous model, when the gusset-rib structure was applied to the joining part of the target products.

Tolerance Design for Parts of a Sliding-Type Mobile Phone to Improve Variational Quality of Its Side Gap (슬라이드형 휴대전화기 측면 갭의 품질개선을 위한 부품 공차설계)

  • Lee, Rae Woo;Chung, Haseung;Jee, Haeseong;Yim, Hyunjune
    • Korean Journal of Computational Design and Engineering
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    • v.17 no.6
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    • pp.398-408
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    • 2012
  • This paper investigates the tolerance stack-up in a commercial sliding-type mobile phone model developed by a Korean electronics company, with focus on the dimensional quality of the gap between the sliding top and the main body. The tolerance analysis in this study is done using a commercial software package, which runs Monte Carlo simulations to produce the statistical distributions of the gap size at desired locations. Such an analysis revealed that the original design did not yield the desired dimensional quality of the gap. Through a series of systematic analyses and syntheses, an improved design is proposed for the nominal dimensions and tolerances of selected features of the parts. The proposed design was validated, through tolerance analysis simulation, to meet the desired requirement of the gap quality.

Analysis on the Friction Losses of a Bent-Axis Type Hydraulic Piston Pump

  • Hong, Yeh-Sun;Doh, Yoon-Ho
    • Journal of Mechanical Science and Technology
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    • v.18 no.9
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    • pp.1668-1679
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    • 2004
  • The design of an axial piston pump for electro-hydrostatic transmission systems requires accurate information where and how much the internal friction and flow losses are produced. This study is particularly focused on the friction losses of a bent-axis type hydraulic piston pump, aiming at finding out which design factors influence its torque efficiency most significantly. To this end, the friction coefficients of the pump parts such as piston heads, spherical joints, shaft bearings, and valve plate were experimentally identified by a specially constructed tribometer. Applying the experimental data to the equations of motion for pistons as well as to the theoretical friction models for the pump parts, the friction torques produced by them were computed. The accuracy of the computed results was confirmed by the comparison with the practical input torque of the pump. In this paper, it is shown that the viscous friction forces on the valve plate and input shaft bearing are the primary source of the friction losses of the bent-axis type pump, while the friction forces and moments on the piston are of little significance.

A Study of Deburring System Using The Image Processing Technique (화상처리 기법을 이용한 디버링 시스템에 관한 연구)

  • Bae, Joon-Young;Joo, Youn-Myoung;Choi, Sang-Kyun;Lee, Sang-Ryong
    • Journal of the Korean Society for Precision Engineering
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    • v.19 no.6
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    • pp.128-135
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    • 2002
  • Burr is a projected part of finished workpiece. It is unavoidable and undesirable by-product of most metal cutting or shearing process. Also, it must be removed to improve the fit of machined parts, safety of workers, and the effectiveness of finishing operation. But deburring process Is one of manufacturing processes that have not been successfully automated, so deburring automation is strongly needed. This paper focused on developing a basic algorithm to find edge of workpiece and match two different image data for deburring automation which includes automatic recognition of parts, generation of deburring tool paths and edge/comer finding ability by analyzing the DXF drawing file which contains information of part geometry. As an algorithm fur corner finding, SUSAN method was chosen. It makes good performance in finding edge and corner in suitable time. And this paper suggested a simple algorithm to find matching point between CCD image and drawing file.

NUMERICAL STUDY ON THE PERFORMANCE CHARACTERISTICS OF SHELL AND TUBE HEAT EXCHANGER BY FLOW DISTRIBUTORS : PART(II) HEAT TRANSFER CHARACTERISTICS (유동분배판에 의한 원통-다관형 열교환기의 성능 특성에 관한 수치해석적 연구(II): 전열특성)

  • Park, Y.M.;Lee, T.H.;Chung, H.T.;Kim, H.B.
    • Journal of computational fluids engineering
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    • v.21 no.4
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    • pp.28-32
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    • 2016
  • In the previous study, it is proved by numerical simulation that the baffle shaped as the porous plate installed in the inlet chambers improves the redistribution of the flow injecting to the tube bundles. In the present study, numerical simulation has been performed to investigate the effects of the flow distributors on the thermal characteristics of the shell and tube heat exchangers. The flow fields have been analysed by the three-dimensional Navier-Stokes solvers including the thermal conditions on the shell sides. The numerical results showed that the presence of the baffles improves the redistribution of the heat transfer to the tube bundles though the overall performance drop slightly on the present flow conditions.

Thermal-structural Coupled Field Analysis for Fire Safety Type Ball Valve (화재 안전용 볼밸브의 열·구조 연성해석)

  • Kim, Si-Pom;Lee, Joon-Ho;Lee, Kwon-Hee;Jeon, Rock-Won;Do, Tae-Wan
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.10 no.3
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    • pp.28-32
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    • 2011
  • The safety of transporting equipment in a cryogenic condition is one of important problems under the circumstances that the application weight of natural gas is gradually increasing. As a larger disaster may be generated by leakage of oil or gas from valves in case of fire occurrence of a ship, the present research applied a numerical analysis method on thermal stress distribution and deformation, etc. to the design of ball valves satisfying fire safety test's specification(API607) to prevent this. In addition, the present research progressed fire safety tests and compared the test result with numerical analysis results. The Max stress by parts was confirmed through thermal analysis of major parts to evaluate safety. The fire safety test was progressed according to the regulation of API607.

Aerodynamic design optimization of an aircraft wing for drag reduction using computational fluid dynamics approach

  • Shiva, Kumar M.R;Srinath, R;Vigneshwar, K;Ravi, Kumar B
    • Wind and Structures
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    • v.31 no.1
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    • pp.15-20
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    • 2020
  • The aircraft industry supports aviation by building aircraft and manufacturing aircraft parts for their maintenance. Fuel economization is one of the biggest concerns in the aircraft industry. The reduction in specific fuel consumption of aircraft can be achieved by a variety of means, simplest and more effective is the one to impose minor modifications in the aircraft main wing or the parts which are exposed to the air flow. This method can lead to a reduction in aerodynamic resistance offered by the air and have a smoother flight. The main objective of this study is to propose geometric design modifications on an existing aircraft wing which acts as a vortex generator and it can reduce the drag and increase lift to drag ratio, leading to lower fuel consumption. The NACA 2412 aircraft wing is modified and designed. Rigorous flow analysis is carried out using computational fluid dynamics based software Ansys Fluent. Results show that saw tooth modification to the main wing shows the best aerodynamic efficiency as compared to other modifications.

Chaotic Behavior on Rocking Vibration of Rigid Body Block Structure under Two-dimensional Sinusoidal Excitation (In the Case of No Sliding)

  • Jeong, Man-Yong;Lee, Hyun-;Kim, Ji-Hoon;Kim, Jeong-Ho;Yang, In-Young
    • Journal of Mechanical Science and Technology
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    • v.17 no.9
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    • pp.1249-1260
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    • 2003
  • This present work focuses on the influence of nonlinearities associated with impact on the rocking behavior of a rigid body block subjected to a two-dimensional excitation in the horizontal and vertical directions. The nonlinearities in rocking system are found to be strongly dependent on the impact between the block and the base that abruptly reduces the kinetic energy. In this study, the rocking systems of the two types are considered : The first is an undamped rocking system model that disregards the energy dissipation during the impact and the second is a damped rocking system, which incorporates energy dissipation during the impact. The response analysis is carried out by a numerical method using a non-dimensional rocking equation in which the variations in the excitation levels are considered. Chaos responses are observed over a wide range of parameter values, and particularly in the case of large vertical displacements, the chaotic characteristics are observed in the time histories, Poincare sections, the power spectral density and the largest Lyapunov exponents of the rocking responses. Complex behavior characteristics of rocking responses are illustrated by the Poincare sections.

3D Printable Composite Materials: A Review and Prospective (3D 프린터용 복합재료 연구 동향)

  • Oh, Eunyoung;Lee, Jinwoo;Suhr, Jonghwan
    • Composites Research
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    • v.31 no.5
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    • pp.192-201
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    • 2018
  • The use of 3D printing for rapid tooling and manufacturing has promised to produce components with complex geometries according to computer designs and it is emerging as the next generation key of manufacturing. Due to the intrinsically limited mechanical/electrical properties and functionalities of printed pure polymer parts, there is a critical need to develop 3D printable polymer composites with high performance. This article gives a review on 3D printing techniques of polymer composite materials and the properties and performance of 3D printed composite parts as well as their potential applications in the various fields.