에어-드롭 해머와 카운터블로 해머 프레스 단조공정의 기계진동 비교해석

김수태,최영휴,주경진 사단법인 유공압건설기계학회 2022 드라이브·컨트롤 Vol.19 No.4

Air-drop hammer press and counterblow hammer press are widely used power-drop forging hammersemploying different forging blow mechanisms. It is important and necessary to analyze mechanical vibrations of these two different hammers in their forging processes in order to develop high performance forging hammers. In this study, these two forging hammers were mathematically modelled as mass-spring-damper systems. For these two different types of forging hammers, the forging efficiency and mechanical vibrations due to hammer forging blow were theoretically analyzed and compared. The force transmitted to the ground was also determined and compared. Especially, effects of mass ratio and restitution coefficient on forging efficiency were investigated.

중력-드롭 해머와 카운터블로 해머 프레스 단조공정의 기계진동 비교해석

김수태(S. T. Kim),주경진(G. J. Ju),신용재(Y. J. Shin),박근종(G. J. Park),최영휴(Y. H. Choi) 유공압건설기계학회 2022 유공압건설기계학회 학술대회논문집 Vol.2022 No.06

단조가공에 사용되는 해머 프레스는 단조과정에서 단조타격으로 인하여 큰 진동과 소음이 발생한다. 단조효율을 높이면서 이러한 진동을 저감하는 것이 단조 해머 프레스의 설계에 있어 매우 중요하다. 본 연구에서는 중력-드롭 해머 프레스와 카운터블로 해머 프레스를 각각 질량-스프링-감쇠기로 모델링하여 단조공정에서 램의 단조타격에 의한 진동응답과 기초 지반에 전달되는 힘을 이론적으로 해석하고 그 결과를 비교한다. 또한 드롭 해머 프레스의 단조효율을 무차원화 변수인 램과 앤빌에 부착된 금형 재료의 반발계수와 램과 앤빌의 질량비의 함수로 구하고, 카운터블로 해머 프레스의 단조효율을 상부 및 하부 램에 부착된 금형재료의 반발계수와 상하 램의 질량비 및 운동량비의 함수로 구하고 두 프레스의 단조효율을 비교한다

유한요소법을 이용한 해머단조 공정에서 타격 횟수의 결정

장성민(S. M. Jang),김성현(S. H. Kim),이민철(M. C. Lee),조범제(B. J. Cho),전만수(M. S. Joun) 한국소성가공학회 2009 한국소성가공학회 학술대회 논문집 Vol.2009 No.10

In this paper, three-dimensional finite element approach to determining the number of blows in hammer forging is presented. Energy efficiency which is a major factor affecting the number of blows in hammer forging is assumed to decrease linearly as die-material contact area increases. The approach is applied to predicting the number of blows in counterblow hammer forging of large crank shaft for medium sized ship engine.

대형크랭크샤프트 해머단조공정의 시뮬레이션 및 실험적 검증

장성민(S. M. Jang),김성현(S. H. Kim),이민철(M. C. Lee),제갈영진(Y. J. Jegal),박태현(T. H. Park),조범제(B. J. Cho),전만수(M. S. Joun) 한국소성가공학회 2010 한국소성가공학회 학술대회 논문집 Vol.2010 No.5

In this paper, non-isothermal analysis of hammer forging process for a large crankshaft is conducted. A simple and computationally efficient approach to non-isothermal three-dimensional hot forging simulation, theoretically based on a rigid-thermoviscoplastic finite element method, is employed. In the approach, it is assumed that the temperatures of dies are increased at the same ratio as the workpiece temperature decreases. Hot forging of a large crankshaft is simulated using AFDEX 3D and the simulated result is compared with the actually forged one in detail. It has been verified that the predictions are in good agreement with the experiments. The successful simulation and development of a large crankshaft by the hammer forging technology will contribute to opening a new area of hammer forging application and to enhancing competitiveness of national machinery industries especially including ship part industries.

카운터블로 해머 프레스 단조공정의 기계진동 특성 해석

김수태,주경진,박근종,최영휴 한국기계가공학회 2022 한국기계가공학회지 Vol.21 No.8

The vibration characteristics of a hammer press are important parameters for machine design and production control. In this study, a counterblow hammer press was mathematically modelled as a mass-spring-damper system in order to analyze its vibration characteristics. The forging efficiency was theoretically derived as a function of the mass ratio, momentum ratio, and the coefficient of restitution And the effects of the mass ratio, momentum ratio and the restitution coefficient on the forging efficiency were also investigated for two particular cases of the unit mass ratio and unit momentum ratio. Additionally, the vibration responses of the counterblow hammer press due to the ram colliding impact were analyzed, and the force transmitted to the foundation through the mounting unit was determined.

반경방향 단조용 초경합금 맨드렐 및 해머 소재의 기계적특성 평가에 관한 시험 연구

사민우 한국기계가공학회 2024 한국기계가공학회지 Vol.23 No.1

This study aims to determine the applicability of mass production of products according to the radial forgingmethod. Mechanical properties and performance were compared and analyzed by exploring cemented carbidematerials that are currently recommended as mandrel and hammer materials. Two samples were prepared toexplore the suitability of cemented carbide materials for cold forging processes, which require wear and impactresistance, and to evaluate their mechanical properties. Tensile strength, bending strength, impact, and wear testswere selected as mechanical property tests. It was confirmed that a specimen made of a tungsten carbidematerial with a high Co content of 18% exhibited excellent impact resistance properties in the hammer material. However, in the wear evaluation, it was confirmed that the low Co content of 12% had less wear.

전통 제철실험을 통해 생산된 단조박편의 재료과학적 특성 연구

조성모,조남철 한국문화재보존과학회 2021 보존과학회지 Vol.37 No.6

제철원료별 직접제련법 복원실험으로 생산된 단조박편의 재료과학적 분석을 통해 금속학적 특성을 규명하였다. 제련을 위해 경주감포사철과 양양철광석을 이용하며, 각각 4개의 그룹을 설정하였 다. 분석은 주성분, 광물 동정, 미세조직 관찰을 하였다. 주성분 분석 결과 정련⋅단접이 진행될수록 Fe의 함량은 증가하고 비금속개재물의 함량은 감소하였다. 광물을 동정한 결과 산화철 계열의 광물이 확 인되었다. 미세조직 관찰 결과 Wüstite, Fayalite가 관찰되었으며, 일부에는 응집된 Wüstite가 관찰되 었다. 일부 다각형, 장주상의 Magnetite도 확인되었다. 또한, 공극 및 불순물, 비금속개재물은 점차 감소하였다. 차후 다양한 제철원료를 이용한 복원실험을 통해 생산된 단조박편의 재료과학적 분석을 통해 금속학적 특성을 규명하고, 이를 유적에서 출토된 단조박편과 비교⋅검토하는 것이 필요하다. This study attempted to investigate the metallurgical characteristic through material scientific analysis of hammer scale produced as a direct smelting method restoration experiment for each raw material of iron. To this end, four hammer scale groups were set up, respectively, by experimenting with Gyeongju-Gampo Iron sand and Yangyang Iron ore. For the analysis, principal component analysis, compound analysis, microstructure observation, and chemical composition were confirmed. As a result of principal component analysis, as forging and refining progressed, the content of Fe increased and the content of non-metallic objects decreased. As a result of compound analysis, iron oxide-based compounds were identified. As a result of confirming microstructure and chemical composition, Wüstite and Fayalite were observed overall, and agglomerated Wüstite were observed in some. Magnetite on shape of polygon and pillar was observed. In addition, it was confirmed that internal defects, impurities, and non-metallic interventions gradually decreased. In the future, it is necessary to investigate the metallurgical characteristic through material scientific analysis of hammer scale produced through restoration experiments using various raw material of iron, and compare them with those excavated from Iron manufacture ruins.

중력-드롭 해머와 카운터블로 해머 프레스 단조공정의 기계진동 비교해석

김수태(S. T. Kim),주경진(G. J. Ju),신용재(Y. J. Shin),박근종(G. J. Park),최영휴(Y. H. Choi) 유공압건설기계학회 2022 유공압건설기계학회 학술대회논문집 Vol.2022 No.6

대형엔진용 자유단조품 생산을 위한 공정 자동화장비 개발

지명국(Myoung Kuk Ji),김영근(Young Keun Kim),장백선(Baek Seon Jang),최창수(Chang Su Choi),김철표(Churl Pyo Kim),정한식(Han Shik Chung),정효민(Hyo Min Jeong) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.10

In mechanical industries, forging is one of the basic process. But comparing the other developed industries, forging industries can not reach at the level of that development. In forging industries, the quality of the products are totally depends on the skills of workers and also the precision of the equipments. Especially in case of open die forging, all processes are manual and the workforce are always exposed to danger. So keeping in view the aspect of danger during open die forging, a development of system has been made in this research, which is based on forklift. In the regard some additional device has been made especially. After than it is fitted with the forklift for safe and easy handling of jobs and products during open die forging process. First of all, development system mold has been assembled to the system, after than it is assembled with forklift. This development system has been applied for handling of large scale products over 300Kg, and the satisfactory result with uniform quality of the products have been achieved due to this mechanical setup.

정련ㆍ단접 공정 재현 실험을 통해 생산된 소재 및 부산물의 재료학적 특성

오민지,조현경,조남철,한정욱 한국문화재보존과학회 2018 보존과학회지 Vol.34 No.2

본 연구는 정련·단접 공정을 재현하고 그 과정에서 발생한 강괴 및 단조박편을 단접 횟수에 따라 분류하여 분석하였다. 강괴의 경우 단접 횟수가 증가함에 따라 불순물과 공극률이 26.09%에서 1.8%로 줄었다. 또한 경도는 평균36.88HV가량 높아졌다. 이는 금속 조직이 점차 치밀해지는 것을 관찰할 수 있었다. 단조박편의 경우 단접 횟수에 따라 전철량이높아졌다. XRD 분석 결과 Quartz, Fayalite, Wüstite, Magnetite가 관찰되며 횟수가 증가함에 따라 Quartz의 양이 낮아졌다. 또한 단접 횟수가 늘어남에 따라 입상(粒狀)의 Wüstite들이 응집(凝集)하여 굵고 긴 백색의 띠 형태로 관찰되었다. 이상의 결과로 정련·단접 공정에서 발생한 강괴 및 단조박편의 횟수별 특징을 알 수 있었으며 향후 고대 제철공정 및 철기제작기술 체계를 정립할 수 있는 기술 자료로 활용할 수 있을 것으로 본다. This study analyzed the influence of folding time on the forge welded bar and hammer scale produced usingthe traditional refining and forge welding reproduction experiment. In the case of the forge welded bar, increasing theforging time decreased the percentage of impurities and porosity from 26.09% to 1.8%. Additionally, the hardness increasedby an average of 36.88 HV. In other words, the microstructure gradually became more precise. For the hammer scale,the amount of T·Fe increased with forging time. X-ray diffraction analysis revealed the presence of quartz, fayalite, wüstite,and magnetite. The amount of quartz decreased as the forging time increased. In addition, as the forging time increased,the granular wüstite changed into a cohesive, long, white band. The results provide information on the characteristicsof the forge welded bar and hammer scale produced in the refining and forging process. This information can be usedas technical data for ancient steel making processes as well as for future technological systems.