• Design & Manufacturing
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• 제2권1호
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• pp.1-5
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• 2008

Restriking method is to add to process in order to get the correct size and high precision accuracy of product which is formed in pre-process. This method is widely used at bending work and drawing work. Restriking die is particularly design and used as restriking process is performed. Therefore, production cost is increasing as one process or a two process are added. In this paper, punches and die block of square shell drawing die which could be performed drawing work and restriking process by using only one die are designed in order to solve these factors. The structure of sectional die which can integrate drawing die and restriking die was developed.

• Design & Manufacturing
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• 제2권1호
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• pp.7-10
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• 2008

Restriking method is to add to process in order to get the correct size and high precision accuracy of product which is formed in pre-process. This method is widely used at bending work and drawing work. Restriking die is particularly design and used as restriking process is performed. Therefore, production cost is increasing as one process or a two process are added. In this paper, punches and die block of square shell drawing die which could be performed drawing work and restriking process by using only one die are designed in order to solve these factors. The structure of sectional die which can integrate drawing die and restriking die was developed.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2000년도 추계학술대회논문집 - 한국공작기계학회
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• pp.249-254
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• 2000

The contact forces between die components for the drawing of large size automotive panels introduce elastic deflections of the die components. Due to the deflections, the gap between blank holder and die varies locally resulting in nonuniform material flow. Such a nonuniform die gap usually requires correcting operation, so called die spotting, which is time consuming trial and error process. To reduce the die spotting time, the optimization of the blank holder bending deflection is needed. In this paper, we implemented an analysis procedure to predict the blank holder deflection. The analysis procedure and design of experiments techniques are applied to the optimization of balance block heights. The optimization results can be used as guidelines in actual die spotting process.

• 한국주조공학회지
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• 제20권3호
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• pp.181-187
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• 2000

There are two types of vacuum die casting, one is known as the chill block method, and the other is the valve block method. Efficiency of the valve block method is better than the chill block method. However purchasing and maintaining cost of the former one is very high, the latter method is popular in many small and medium die casting shops. Simple evacuation system using chill vent was prepared to investigate the effect of the air pressure, hose length and chill vent type on the pressure change in die cavity in this study. The rate of evacuation was influenced by the evacuation method, chill vent condition and hose length. Evacuation time became longer and vacuum level lower when evacuating cavity via chill vent. It took a longer time to evacuate the cavity when a longer hose was used. Vacuum level in the cavity also decreased with increase in hose length.

• 한국산학기술학회논문지
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• 제11권2호
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• pp.420-425
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• 2010

온간단조(warm forging) 가공은 가공소재(Billet)를 $800^{\circ}C$ 정도로 가열하여 금형의 다이블록 임프레션(impression) 상면(上面)에 위치결정 시켜 단조하고 있는데, 이 단조가공 과정에서 산화스케일의 비산에 따른 작업자의 화상에 대한 위험도와 산화스케일이 다이블록의 임프레이션에 부착 되거나 열처리기술 미흡으로 금형수명(die life)을 단축시키며 다이블록 안에 분무하는 이형제는 유해먼지, 유해증기, 미스트, 퓸, 악취 등을 발생시켜 작업장 환경을 오염시킴으로써 직무기피 직종으로 분리되기 때문에 생산량 목표 달성에 큰 문제점으로 대두 되고 있다. 더욱이 다이블록의 임프레이션 마멸부위를 수리보수하기 위한 재생공법의 미흡으로 납기지연, 금형비 상승의 요인으로 나타나므로 이에 대한 재생공법 개선과 작업장의 공해물 제거장치의 개발이 요망되고 있다. 본 연구에서는 황동제 관 이음쇠의 온간단조가공에서 도출된 빌릿가열시 문제점, 금형재생 보수시 문제점, 제조원가의 상승요인 등을 외국의 기술과 비교하여 온간단조 금형제작방법개선, 금형재생보수공법 개선, 유해가스 제거장치를 도입하여 환경친화형 작업장 개선 등으로 문제점을 해결 하고자 하였다.

• Design & Manufacturing
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• 제8권1호
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• pp.27-30
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• 2014

Alloy tool steel such as SKD11 and SKD61 or high speed tool like SKH51 are used as materials for semiconductor dies. Cavities, curl blocks, pot blocks and housings are made from those materials. To make those parts from alloy tool steel or high speed tool, one utilizes discharge machining, and mechanical machining including machining center, milling, drilling, forming grinding and others. In the process of cutting machining and polishing, the die materials become unsuitable for machining owing to bubbles and foreign substances in them, which hinders production process. Therefore, this study focuses on die material selection criteria, and on analysis and comparison of material characteristics to help companies to solve their problems, make die manufacture less burdensome and extend die life.

• 한국공작기계학회논문집
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• 제10권3호
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• pp.68-74
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• 2001

In the drawing of large size automotive panels, elastic deflection of die components is induced by the contact force between them. The deflection is nonuniform and locally distributed, and results in nonuniform material flow. In order to arrange such a nonuniform die gap, a correcting operation, so called die spotting, is inevitable, which requires trial and error works and consuming time. A prediction of the bending deflection prior to a try-out must be useful to reduce the die spotting time. In this study, drawing process of a front fender is simulated first. and the deflection of the blank holder is calculated from the contact force imposing on th blank holder. The balance block heights ensuring a uniform deflection are optimized by the analysis and design of experiments.

• 소성∙가공
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• 제31권1호
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• pp.5-10
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• 2022

In multi-stage cold forging process, to enhance the productivity and product quality, in-site process monitoring technique by implanting sensors such as piezo-sensor and acoustic emission sensor has been continuously studied. For accurate analysis of the process, the selection of appropriate sensors and implantation positions are very important. Until now, in a multi-state forging machine, wedge parts located at the end of punch-set are used but it is difficult to analyze minute changes in die block-set. In this study, we also implanted sensors to the die part (die spacer) and compared signals from both sensors and found that sensing signals from die part showed enhanced process monitoring results.

• 소성∙가공
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• 제6권3호
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• pp.192-202
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• 1997

This study presents an effect of number of passes in wire-cut electric discharge machining on fine blanking dies and products. Three part fine blanking dies were produced by the difference of numbers of passes discharge machining. Brake pad was produced, through the die produced like that, the objective of this study is the improvement in surface roughness of die block and punch, life extension of die block, the decrease of second fracture dimensions, the rise of productive.

• 한국산학기술학회논문지
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• 제11권1호
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• pp.49-54
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• 2010

자동차의 A.C 제너레이터(alternating current generator) 부품으로 사용되는 로터폴(rotor pole)을 가공할 때는 트랜스퍼온간단조금형(transfer warm forging die)으로 성형한다. 소재를 온간가공 영역으로 가열한 후 즉시 금형안으로 이송시켜 제1스테이지(1st stage)에서 업세팅가공(upsetting work)하고 제2스테이지(2nd stage)로 이송하여 측방압출(lateral extrusion)가공을 한다. 이때 측방압출 스테이지의 금형에서 다이블록(die block), 다이부싱(die bushing), 센터펀치(center punch), 사이드펀치(side punch)의 접촉면이 압출시의 과혹(過酷)한 조건에 견디지 못하여 쉽게 마멸(abrasion)되어 금형수명(die life)을 단축시키고 있다. 이 때문에 생산량 감소로 인한 납기지연, 금형의 수리보수시간 과다, 제품의 정밀도 저하 등의 문제점이 발생되고 있다. 이러한 문제점을 해결하기 위하여 금형재질 선정과 열처리 작업 싸이클 개선, 방전가공시의 트러블 해소, 핵심부품의 구조변경 등을 연구하여 금형수명을 40~50% 연장 하고자 하였다.