A Study on the Impact Test Analysis of Specimens for Designing the Housing of Precision Guided Projectile

고준복(Jun bok Ko),이소담(So dam Yi),박은주(Eun joo Park),백기봉(Ki bong Baek),김명섭(Myeong seop Kim),서석훈(Suhk hoon Suh) Korean Society for Precision Engineering 2019 한국정밀공학회지 Vol.36 No.6

The precision-guided projectile is a weapon system for precision attacks, and the cannon-launched projectile is guided by a control device. The electrical actuator system is a subsystem of the control device, and the whole projectile undergoes high axial and lateral impact force for 1 to 10mseconds. In this study, a charpy, and a tensile impact analysis were conducted, using specimens made in the materials of SUS630 and Al7075-T6 to understand fracture mechanics and impact property, such as energy change rate. The impact analysis and gas-gun impact test were conducted, to validate the optimized housing model.

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 Ultra-Precision Grinding Processing for Aspheric Glass Array Lens WC Core

고명진(Myeong Jin Ko),박순섭(Soon Sub Park) Korean Society for Precision Engineering 2016 한국정밀공학회지 Vol.33 No.11

Plastic array lens are cheap to manufacture; however, plastic is not resistant to high temperatures and moisture. Optical glass represents a better solution but is a more-expensive alternative. Glass array lens can be produced using lithography or precision-molding techniques. The lithography process is commonly used, for instance, in the semiconductor industry; however, the manufacturing costs are high, the processing time is quite long, and spherical aberration is a problem. To obtain high-order aspherical shapes, mold-core manufacturing is conducted through ultra-precision grinding machining. In this paper, a 4 X 1 mold core was manufactured using an ultra-precision machine with a jig for the injection molding of an aspherical array lens. The machined mold core was measured using the Form TalySurf PGI 2+ contact-stylus profilometer. The measurement data of the mold core are suitable for the design criterion of below 0.5 ㎛.

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.

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.

A Study on the Optimum Design of the Spindle Taper Angle by Chucking Force of a 2-Head Simultaneous Grinding Machine

이춘만(Choon-Man Lee),이정학(Jeong-Hak Lee),정호인(Ho-In Jeong),이정훈(Jeong-Hun Lee) Korean Society for Precision Engineering 2021 한국정밀공학회지 Vol.38 No.2

In recent years, the machine industry has demanded high precision of the processed products and high efficiency of production due to the rapid development of technology. The grinding machine is being studied in many countries. The typical grinding machine is processed in the order of one side each. However, a 2-head simultaneous grinding machine processes both sides at the same time. Therefore, it has reduced processing time and improved precision. In this study, the overall structural analysis of a 2-head simultaneous grinding machine with high precision and high efficiency of productivity was performed. For high precision of the 2-head simultaneous grinding machine, the spindle taper angle was analyzed and optimized. When the spindle taper angle was 16 degrees, it had the highest chucking force. Therefore, the spindle had high precision as the spindle taper had the strongest force to chuck the collet. The analysis results can be applied to further develop the 2-head simultaneous grinding machine.

Development and Experimental Performance Validation of Torsional Viscosity Damper for Crank Shaft System of Transporting Machine

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.

Detection of Absolute Position for Magneto-Optical Encoder Using Linear Table Compensation

김슬기(Seul Ki Kim),김형준(Hyeong Jun Kim),이석(Suk Lee),박성현(Sung Hyun Park),이경창(Kyung Chang Lee) Korean Society for Precision Engineering 2016 한국정밀공학회지 Vol.33 No.12

This paper presents the development of a magneto-optical encoder for higher precision and smaller size. In general, optical encoders can have very high precision based on the position information of the slate, while their sizes tend to be larger due to the presence of complex and large components, such as an optical module. In contrast, magnetic encoders have exactly the opposite characteristics, i.e., small size and low precision. In order to achieve encoder features encompassing the advantages of both optical and magnetic encoders, i.e., high precision and small size, we designed a magneto-optical encoder and developed a method to detect absolute position, by compensating for the error of the hall sensor using the linear table compensation method. The performance of the magneto-optical encoder was evaluated through an experimental testbed.