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Geometrical Compensation of Injection-Molded Thin-Walled Parts in Reverse Engineering
Kim Yeun Sul,Lee Hi Koan,Huang Jing Chung,Kong Young Sik,Yang Gyun Eui Korean Society for Precision Engineering 2005 International Journal of Precision Engineering and Vol.6 No.2
A geometric compensation of thin-walled molded parts in reverse engineering is presented. Researches in reverse engineering have focused on the fitting of points to curves and surfaces. However, the reconstructed model is not the geometric model because the molded parts have some dimensional errors in measurements and deformation during molding. Geometric information can give an improved accuracy in reverse engineering. Thus, measurement data must be compensated with geometric information to reconstruct the mathematical model. The functional and geometric concepts of the part can be derived from geometric information. LSM (Least square method) is adopted to determine the geometric information. Also, an example of geometric compensation is given to improve the accuracy of geometric model and to inspect the reconstructed model.
Study on the Reconstruction of Skull Prototype using CT image and Laser Scanner
Hur, Sung-Min,Lee, Seok-Hee Korean Society for Precision Engineering 2000 International Journal of Precision Engineering and Vol.1 No.1
The importance of shape reconstruction is increasing in many areas such as RPD(Rapid Product Development) and reverse engineering. Typical data in these areas are mainly classified as the shape data measured by a laser scanner and the data extracted from the CT image. The goal of this research is to realize three-dimensional shape construction by showing a possible way to analyze input image data and reconstruct the original shape. Two main steps of the reconstructing process are obtaining cross-section data from image processing and linking loops between one slice and the next. Objects reconstructed in this way are compared with other objects using a laser scanner and modelled by commercially available software. The technique is expected to be used in reverse engineering applications and the object modeling with automated process.
Free-form Surface Generation from Measuring Points using Laser Scanner
Park, Jae-Won,Hur, Sugn-Min,Lee, Seok-Hee Korean Society for Precision Engineering 2002 International Journal of the Korean Society of Pre Vol.3 No.4
With the development of a laser scanner of high precision and increased speed, reverse engineering becomes a key approach to reduce the time for the development of new products. But the modeling process is not so automated enough until now. Modeling in real workshops is usually performed by the experienced operators and it requires a skillful technique to get the resultant surface of high quality and precision. In this paper, a systematic solution is proposed to automate the free-form surface generation from the measured point data. Compatibility is imposed to the measured point data during input curve generation. And the compatibility of cross-sectional curve is also considered for the loft surface generation. The data in each step is produced in IGES file format to make an easy interface to other CAD/CAM software without any further data manipulation.
Structural Integrity Analysis and Evaluation of Cooled Cooling Air Heat Exchanger for Aero Engine
Kim, Na-Hyun,Cho, Jong-Rae,Ra, Yong-Jae Korean Society for Precision Engineering 2018 International Journal of Precision Engineering and Vol.19 No.4
The rise in air traffic demand has led to the escalation of concerns about environmental effects, such as pollution emission. Thus, developing a technology that would reduce environmental problems is more urgent. One of the methods for reducing gas emission is to increase the combustion temperature, which, unfortunately, increases the turbine blade temperature. This problem can be solved by installing a heat exchanger on the engine. However, developing the appropriate heat exchanger that can withstand the severe operating conditions of an aircraft engine is difficult. Thus, a heat exchanger has not yet been installed in an aero engine, but is still being developed. This study aims to assess the structural integrity of the heat exchanger being developed. A finite element (FE) analysis was performed under certain flight operating conditions. The surface temperature was measured during the performance test to verify the thermal boundary conditions. The analysis results were then evaluated according to the fatigue strength of Inconel 625 at <TEX>$10^4$</TEX> cycles. Moreover, a transient analysis was conducted to identify the analysis results under a steady state. Its results were compared with those of a static analysis. The comparison showed an acceptable result in their differences. Therefore, the static analysis results of the full model are considered reasonable.
Manufacturing and Mechanical Evaluation of Cooled Cooling Air (CCA) Heat Exchanger for Aero Engine
Kim, Chang-Soo,Kim, Hyeon-Jun,Cho, Jong-Rae,Park, Sang-Hu,Ha, Man-Yeong Korean Society for Precision Engineering 2016 International Journal of Precision Engineering and Vol.17 No.9
Recent studies on improving the efficiency of gas turbine engines have focused on increasing the inlet temperature of gas flowing into the turbine. For the high inlet temperature, it requires the development of a super-alloy based material that can withstand harsh operating conditions. However, it is essential to utilize alternative solutions such as turbine blade cooling technology. Unfortunately, lightweight, high performance, and high mechanical reliable heat exchangers for aircraft have not yet been examined because of the difficulties associated with design optimization and reliability verification under high temperatures and pressures. The purpose of this study is to develop a manufacturing process for a heat exchanger that can be used in aircraft gas turbine engines. The manufacturing process involved preparing fine tubes through multi-step drawing and annealing processes, and joining these to a tube sheet through brazing. In this work, we reported on the total fabrication processes and mechanical integrity tests of a cooled cooling air (CCA) heat exchanger for the aircraft turbine engine. Through the work, a prototype model of a heat exchanger based on a gas turbine assembly was then developed using each of the individual processes. An X-ray CT test and an endoscopy test were performed to inspect the heat exchanger. The results indicated good manufacturing integrity; thus, the developed heat exchanger can be used for cooling turbine blades.
Hong, Do-Kwan,Ahn, Chan-Woo,Shim, Jae-Joon,Lee, Sang-Suk,Jung, Young-Duk Korean Society for Precision Engineering 2015 International Journal of Precision Engineering and Vol.16 No.7
The purpose of the present study is to deal with the development of a viscosity damper for the crank shaft system of a transporting machine using reverse engineering. A viscosity damper is developed to substitute import product. An engine simulator for performance evaluation has been produced to enable the control of engine speed using a PID controller and to evaluate the performance of several models by reverse engineering. Several prototypes are made according to the mass variation of an inertia ring. To evaluate the reduction effect of torsional vibration by viscosity damper, several sensors are used such as microphone, tri-axis accelerometer and the optical fibre sensor. In addition, order tracking and FFT (Fast Fourier Transform) analysis are performed by FFT analyzer and F/V converter according to speed increase (1,000~4,000 rpm). The viscosity damper for a high performance to reduce torsional vibration has been developed successfully using several designs, structural stability analysis and manufacturing techniques, as well as performance tests.
Development of an Electronically Controlled Variable Displacement Vane Pump for Engine Lubrication
Truong, Dinh Quang,Truong, Bui Ngoc Minh,Ahn, Kyoung Kwan,Lee, Jae Shin Korean Society for Precision Engineering 2015 International Journal of Precision Engineering and Vol.16 No.9
Lubrication is one of the most important factors in developing internal combustion engines. And vane pumps are known as potential choices for conducting the engine lubrication systems. To better optimize the lubrication performance, an electronically controlled variable displacement vane pump developed from a typical vane pump is newly introduced in this paper. Firstly, the concept and methodology to design properly an electric actuator to provide an additionally degree of pump control by regulating the pump displacement is carefully considered. Secondly, a control logic is developed to manage the operation of the actuator and subsequently, smoothly varying the pump output in order to satisfy any given lubrication profile. Finally, test rigs are setup to investigate the performances of the fabricated actuator and pump prototype. Practical tests are performed to evaluate the effectiveness of the newly pump design over the typical one.
Application of Expert System for Non-Axisymmetric Deep Drawing Products
Park, Diong-Hwan,Kang, Sung-Soo Korean Society for Precision Engineering 2001 International Journal of Precision Engineering and Vol.2 No.1
An ecpert system for rotationally symmetric deep drawing products has been developed. The application for non-axisymmetric components, however, has not been reported yet. This study construsctus and expert system for non-axisymmetric motor frame which shape is classified into ellipse in deep draqing process and investigates process sequence design with elliptical shape. The developed system consists of four modules. The first is recognition of calculate surface area for non-axisymmetric products. The third is blank design module the creates an oval-shaped blank with the same surface area. The fourth is a processplanning module based on production rules that play the best important roles in an expert system for manufacturing .The production rules are generated and upgraded by interviewing field engineers. Especially, drawing coefficient, punch and die radii for elliptical shape products are considered as main design parameters. The constructed system for elliptical deep drawing product would be very useful to reduce lead time and improve accuracy for products.
Self Displacement Sensing (SDS) Nano Stage
Choi, Soo-Chang,Park, Jeong-Woo,Kim, Yong-Woo,Lee, Deug-Woo Korean Society for Precision Engineering 2007 International Journal of Precision Engineering and Vol.8 No.2
This paper describes the development of a nano-positioning system for nanoscale science and engineering. Conventional positioning systems, which can be expensive and complicated, require the use of laser interferometers or capacitive transducers to measure nanoscale displacements of the stage. In this study, a new self-displacement sensing (SDS) nano-stage was developed using mechanical magnification of its displacement signal. The SDS nano-stage measured the displacement of its movement using a position-sensitive photodiode (PSPD), a laser source, and a hinge-connected rotating mirror plate. A beam from a laser diode was focused onto the middle of the plate with the rotating mirror. The position variation of the reflected beam from the mirror rotation was then monitored by the PSPD. Finally, the PSPD measured the amplified displacement as opposed to the actual movement of the stage via an optical lever mechanism, providing the ability to more precisely control the nanoscale stage. The displacement amplification process was modeled by structural analysis. The simulation results of the amplification ratio showed that the distance variation between the PSPD and the mirror plate as well as the length L of the mirror plate could be used as the basic design parameters for a SDS nano-stage. The PSPD was originally designed for a total travel range of 30 to 60 mm, and the SDS nano-stage amplified that range by a factor of 15 to 25. Based on these results, a SDS nano-stage was fabricated using principle of displacement amplification.