• 대한기계학회논문집
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• 제18권8호
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• pp.2039-2052
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• 1994

In this study, an expert system for multi-stage cold forging process design of axisymmetric parts is developed. The available geometries are axisymmetric shape and cylinder with a hold in one end. The overall system is composed of knowledge-based system for process sequence design, output module interfaced with CAD system and material data-base. In the developed system, designed process can be modified in order to reduce the number of processes and make the distribution of forming load be almost equal at various deforming stages within the machine capacity. After process sequence design is completed, results can be stored as a text file or a commercial CAD system file. The capabilities of the developed system are illustrated through various examples of process design.

• 소성∙가공
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• 제20권4호
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• pp.291-295
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• 2011

The injector housing has two functions, namely, positioning the injector and protecting it from coolant. The conventional manufacturing process of the injector housing by machining has some drawbacks such as considerable loss of material and environmental pollution caused by excessive use of cutting oil. In this paper, precision cold forging is proposed as a new manufacturing process in order to improve these issues. A numerical study was conducted to compute the metal flow, strain, load and other process variables using DEFORM-2D, a finite element analysis(FEA) code for metal forming. Two process methods were investigated and optimal conditions were computed with the FEA code. A prototype was manufactured from the optimal process method and the metal flow and hardness were obtained from the prototype.

• 한국산학기술학회논문지
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• 제7권3호
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• pp.298-307
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• 2006

본 논문에서 HDPE 관의 일체형 TEE성형 공정은 강소성 유한요소 해석 프로그램인 DEFORM-3D를 이용하여 해석을 하였다. 이중 보온관에서 외관으로 사용되는 HDPE 관은 관을 통하여 흐르는 온수의 온도를 유지하기 위한 관으로, TEE는 주관에 가지관을 연결하여 열의 수송방향을 바꾸는 역할을 한다. TEE제작에 압출 용접(Extrusion Welding)을 사용하는 기존의 방법으로는 이음부에서 강도가 취약한 문제점이 발생하기 때문에 HDPE 관을 성형시켜 TEE 형태로 일체화시킨 후에 맞대기 용접(Butt Welding)을 하는 방식을 제안하였다. 열간과 냉간 성형 실험을 실시하였고, 초기 구멍 형태에 따른 모델 파라미터가 강소성 유한요소해석에 의해 규명되어 졌으며, 이는 실제의 제품 제조 공정에 적용되어 졌다.

• Design & Manufacturing
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• 제7권1호
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• pp.28-33
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• 2013

During the cold forming, due to high working pressure acting on the die surface, failure mechanics must be considered before die design. One of the main reasons of die failure in industrial application of metal forming technologies is wear. The mechanisms of wear are consisted of adhesion, abrasion, erosion and so on. Die wear affects the tolerances of formed parts, metal flow, and costs of process. The only way to control these failures is to develop a prediction method on die wear suitable in the design state in order to optimize the process. The wear system is used to analyse 'operating variables' and 'system structure'. In this study, with AISI D2, AISI 1020, AISI 304SS materials, a series of the wear experiments of pin-on-disk type to obtain the wear coefficients from Archard's wear model and the upsetting processes are carried out to observe the wear phenomenon during the cold forming process. The analysis of upsetting processes are performed by the rigid-plastic finite element method. The result of the analysis is used to investigate the die wear the processes, and the analysis simulated die wear profiles are compared with the experimental measured die wear profiles.

• 한국정밀공학회지
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• 제32권11호
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• pp.977-982
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• 2015

This study uses finite element analysis to evaluate the forming load of tool entrance angle of the cold forward extrusion molding process of helical gear; this can replace the spur gear applied to the Electronic Parking Brake (EPB) system. A cold forging process is often used in the automobile industry as well as in various industrial machines due to its high efficiency. Finite element analysis is frequently used when interpreting results of the forging process. Formality was evaluated by calculating tooth profile filling rate of helical gear. Change in required forming load was investigated when the entrance angle of forward extrusion tool die was changed from $30^{\circ}$ to $60^{\circ}$, also by finite element analysis. We suggest suitable tool entrance angles.

• 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.

• 한국기계가공학회지
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• 제8권1호
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• pp.24-30
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• 2009

In this paper, the effect of heat treatment on forgeability is investigated and an improved heat treatment cycle is proposed for the bearing steel, SUJ2. An application example of a bearing inner race cold forging, which has small cracks in the bottom after backward extrusion and piercing, is found from a cold forging industry. The process is evaluated by finite element analysis and several heat treatment cycles are examined in order to propose an improved heat treatment cycle. The effect of heat treatment on material hardness and tool life, dimensional accuracy and forming load is revealed through experiment.

• 한국분말재료학회지
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• 제11권4호
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• pp.301-307
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• 2004

Successful implementation of the powder forming process requires a detailed understanding of several interacting phenomena. The aim is to better control the process variables and to optimize the design parameters. A number of studies were carried out using various constitutive models that take the density change during powder forming into account. Most of them were developed for powders and sintered porous metals, but few of them can describe powder agglomerates, whose behaviour is different from that of uniformly arranged powders. The modification is needed to account for the effect of agglomeration on densification behaviour. Incorporating powder agglomeration into a constitutive model is of considerable importance, as it provides a possibility of relating the powder densification response to microstructural characteristics of powder particles, especially in case of nano powders. In this paper, we proposed a new powder agglomerate model in order to describe the unique densification behaviour of nano powders. The proposed model was applied to the densification of powder agglomerates during cold isostatic pressing.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 The 8th Asian Symposium on Precision Forging ASPF
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• pp.67-72
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• 2003

The cold precision forging of spur gears has been researched, and the effects of relief-hole shape and forging process on the spur gears forming has been analyzed. The results present that the forging load decreases when a suitability diameter of relief-hole is chosen, but the function is not obvious. The spur gears precision forging method with an adjustable movement of concave mould can benefit both the top and the bottom comers forming of the spur gears, full fill the tooth cavity, and decrease the forging load.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2009년도 춘계학술발표논문집
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• pp.525-527
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• 2009

본 논문에서는 자동차 공조부품인 리시버드라이어로서 플랜지와 바디로 구성되어 있다. 리시버드라이어는 냉매 중 포함된 습기 및 기타 불순물을 차단하는 부품으로서 사이트글라스가 부착되어 냉매의 흐름의 상태를 알 수 있다. 또한 압력 밸브가 부착되어 있어 냉매 회로의 압력과 온도가 상승하면 녹아서 냉매를 배출하므로 배관이나 부품들의 압력에 의해서 파괴되는 것을 방지 할 수 있다. 최근 경제적 성형에 관심이 많아 대표적 성형공정인 냉간단조를 적용하여 소재 회수율 및 절삭 비용 등을 절감하는데 목적을 두었다. 냉간단조를 적용하여 자동차 공조 부품인 플랜지와 바디를 개발하는데 공정설계, 금형설계, 금형제작 기술을 확보하였다.