• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.252-252
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• 2000

The Resistance Spot Welding (RSW) has been considered as an inherently safe and reliable method far joining metals, and has been widely employed, especially in automobile body assembly shops, as a manufacturing process. In recent years, the requirement for more sophisticated quality control procedures has considerably grown in the mass production industries. The object of the application of servo control to spot welding gun is the improvement of quality control in the spot welding, one of conventional industrial areas. The important factors affecting welding qualities (shear strength, nuggest size, indentation depth) are welding current, welding time, and gun press force. Welding current and welding time are controlled by welding timer. But, the conventional welding guns using compressed air are out of control in changing gun press forces in welding process. In this paper, a servo gun welding system having a AC servo motor and a PC control system is presented. The main object of this paper is to estimate the influence of gun press force changes in the welding process (press time -> welding time -> hold time) to welding qualities, and to evaluate welding qualities in real time, by recognizing the patterns of gun press forces changed in the welding process and comparing with the standard patterns.

• Journal of Welding and Joining
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• v.23 no.3
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• pp.40-46
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• 2005

Air gun has been one of the good tools to press two sheet metals. However, it is not easy to control the acting force precisely. A Servo-gun is a good tool to control the acting force on the workpiece comparing with the air gun. Servo-gun has a higher tensile shear strength and lower indentation depth as well as smaller spatter. Dynamic resistance was obtained according to the acting force and welding current. As the acting force was changed during welding, the welding quality was increased.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.46.6-46
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• 2001

A servo gun welding system having a AC servo motor and a PC control system is presented for the improvement of quality control in the spot welding. The spot welding process is composed of the press stage, the weld stage, and the hold stage. The changes of gun press forces according to three stages in the spot welding process are controlled and measured through the load cell in order to know the influence on the welding quality. The relation between the measured force changes according to three stages and welding qualities is also implemented on the multilayer perceptrons, one of supervised learning method of neural network, which are powerful for realization of complex mapping characteristics. The estimated results and ...

• Journal of the Korean Society for Precision Engineering
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• v.23 no.10
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• pp.96-102
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• 2006

This paper presents the mechanics of the link of a double-action link-type hydraulic die set for the enclosed die forging. Operational principle of the die set in the enclosed die forging is introduced with emphasis on force transmission from the press and the hydraulic system to the material through links, die components and punches. The force exerted on the link is statically investigated and its structural analysis is carried out. The analyzed results are discussed to be used for design of the link system.

• Design & Manufacturing
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• v.14 no.3
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• pp.50-56
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• 2020

Ceramic tile is widely used as a floor or interior decoration of buildings. The main processes are raw material blending, molding, drying, firing, etc., and since dimensional and quality stability are very important, they are generally molded by a dry press method. In ceramic tile molds, there is a liner that can be easily replaced in case of wear. The liner is constantly abrasion due to a continuous pressing process during tile forming, and it is required to be replaced every certain period. Even in the liner, use a wear-resistant fitting material only in areas where wear is concentrated. However, there was a risk that the fitting material was applied to large-sized tile molding due to problems such as damage to the molding machine and decrease in productivity when detached during the actual tile molding process due to weak fitting strength with the liner. Therefore, in this study, thermal-structural analysis for fitting tolerance analysis and structural analysis for fitting force analysis were performed for the shrink fit process of the fitting material.

• Structural Engineering and Mechanics
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• v.60 no.5
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• pp.829-849
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• 2016

In this paper, experimental as well as numerical analysis of Glass Fiber Reinforced Polymer (GFRP) laminated composite has been presented under ballistic impact with varying projectile nose shapes (conical, ogival and spherical) and incidence velocities. The experimental impact tests on GFRP composite plate reinforced with woven glass fiber ($0^{\circ}/90^{\circ}$)s are performed by using pneumatic gun. A three dimensional finite element model is developed in AUTODYN hydro code to validate the experimental results and to study the ballistic perforation characteristic of the target with different parametric variations. The influence of projectile nose shapes, plate thickness and incidence velocity on the variation of residual velocity, ballistic limit, contact force-time histories, energy absorption, damage pattern and damage area in the composite target have been studied. The material characterization of GFRP composite is carried out as required for the progressive damage analysis of composite. The numerical results from the present FE model in terms of residual velocity, absorbed energy, damage pattern and damage area are having close agreement with the results from the experimental impact tests.

• Structural Engineering and Mechanics
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• v.42 no.3
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• pp.425-448
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• 2012

In this paper, a new damage detection and quantification method has been presented to perform detection and quantification of structural damage under ambient vibration loadings. To extract modal properties of the structural system under ambient excitation, natural excitation technique (NExT) and eigensystem realization algorithm (ERA) are employed. Sensitivity matrices of the dynamic residual force vector have been derived and used in the parameter subset selection method to identify multiple damaged locations. In the sequel, the steady state genetic algorithm (SSGA) is used to determine quantified levels of the identified damage by minimizing errors in the modal flexibility matrix. In this study, performance of the proposed damage detection and quantification methodology is evaluated using a finite element model of a truss structure with considerations of possible experimental errors and noises. A series of numerical examples with five different damage scenarios including a challengingly small damage level demonstrates that the proposed methodology can efficaciously detect and quantify damage under noisy ambient vibrations.

• Design & Manufacturing
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• v.17 no.1
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• pp.13-19
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• 2023

Blanking processing is one of the shear processing method in which the cut part becomes a product and piercing processing is a press molding process in which the cut part is discarded as a scrap. The shear angle of the punch used for blanking is determined by conditions such as the characteristics of the shear material, shear thickness and shear length. The shear angle of a punch is an important factor in determining the size of the shear load, the life of the shear punch, the deformation of the shear product and the quality of burrs In this study, blanking punches applied with four types of shear angles (i.e., 0°, 0°23", 0°46", 0°69") to the blanking punches of bracket products used in practical work were manufactured and tested. In the blanking experiment, the remaining variables except for the shear angle were the same. Experiments show that the product has the least amount of deformation in blanking punches with a shear angle equal to the material thickness, i.e., 0°46"..

• Smart Structures and Systems
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• v.5 no.1
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• pp.1-21
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• 2009

A two-stage damage detection method is proposed and demonstrated for structural health monitoring. In the first stage, the subset selection method is applied for the identification of the multiple damage locations. In the second stage, the damage severities of the identified damaged elements are determined applying SSGA to solve the optimization problem. In this method, the sensitivities of residual force vectors with respect to damage parameters are employed for the subset selection process. This approach is particularly efficient in detecting multiple damage locations. The SEREP is applied as needed to expand the identified mode shapes while using a limited number of sensors. Uncertainties in the stiffness of the elements are also considered as a source of modeling errors to investigate their effects on the performance of the proposed method in detecting damage in real-life structures. Through a series of illustrative examples, the proposed two-stage damage detection method is demonstrated to be a reliable tool for identifying and quantifying multiple damage locations within diverse structural systems.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.95-98
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• 2006

Filtration by fibrous filter is one of the Principle methods used for removing pollutant particles in the liquid. Because of the increasing need to protect both human health and valuable devices from exposure to fine particles, filtration has become more important. Filters have been developed with modified surface charge characteristics to capture and adsorb particles by electrokinetic interaction between the filter surface and particles contained in water. The main purposes of this study are to develop and evaluate the performance evaluation of the apparatus for making a positively charged porous filter media and to analyze the surface characteristics of the filter media for capturing negavitely charged contaminants mainly bacteria and virus from water. The experimental apparatus consists of a mixing tank, a vacuum pumping system, a injection nozzle, a roller press and a controller. The filter media is composed of glass fiber(50-750 nm), cellulose($10-20{\mu}m$) and colloidal charge modifier. The characteristics of filter media is analyzed by SEM(Scanning Electron Microscopy), AFM(Atomic Force Microscopy) and quantified by measuring the zeta potential values.