• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2001년도 제4회 압출 및 인발가공 심포지엄
• /
• pp.99-106
• /
• 2001

The design for cold extrusion dies is very important, because the die insert is subjected to very high radial and hoop stresses. The design of cold extrusion dies has many constrained conditions. In this paper, the used assumptions are such that the yield strength of each ring is selected according to the allowable tensile or compressive hoop stress in each ring and the maximum allowable inner pressure, when yielding occurs in one ring of the dies, is obtained by the proposed equation. In order to obtain design variables, such as diameter ratios and interferences, using the maximum inner pressure, the flexible tolerance method was used for shrink-fitted thick-walled cylinders. ANSYS APDL was used to perform the repeated analysis of deformation of the dies due to the variation of the design variables. The response surface methodology is utilized to analyze the relationship between the design variables and the maximum radial displacement of the die insert during extrusion. From the results, it is found that outer diameter of the die Insert has the largest effect on the minimization of maximum radial displacement at the inner surface of the dies.

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

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2002년도 제7회 단조 심포지엄
• /
• pp.85-91
• /
• 2002

Of all the many types of machine elements which exist today, gears are among the most commonly used. Many researches have been done to manufacture helical gears by cold forging and extrusion. Although cold forging and extrusion were applied to some bevel, spur, and helical gears, problems in connection with reducing forming load and tool life still make it difficult for the related methods to be commercialized. In this study, focusing on reducing load in forming helical gears, extrusion of helical gears by a two-step process is proposed. The process is composed of an extrusion step of spur gears used as preform and a torsion step of the preform to make helical gears. Upper-bound analysis for the two-step process is performed and compared with results of experiments. The newly proposed method can be used as an advanced forming technique to remarkably reduce the forming load and replace the conventional forming process of helical gears.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2002년도 추계학술대회 논문집
• /
• pp.824-828
• /
• 2002

Of all the many types of machine elements which exist today, gears are among the most commonly used. Many researches have been done to manufacture helical gears by cold forging and extrusion. Although cold forging and extrusion were applied to some bevel, spur, and helical gears, problems in connection with reducing forming load and tool life still make it difficult for the related methods to be commercialized. In this study, focusing on reducing load in forming helical gears, extrusion of helical gears by a two-step process is proposed. The process is composed of an extrusion step of spur gears used as preform and a torsion step of the preform to make helical gears. Upper-bound analysis for the two-step process is performed and compared with results of experiments. The newly proposed method can be used as an advanced forming technique to remarkably reduce the forming load and replace the conventional forming process of helical gears.

• 한국식품영양과학회지
• /
• 제33권5호
• /
• pp.899-904
• /
• 2004

압출성형공법을 이용한 수삼의 전처리를 통한 추출수율의 향상과 최적조건에서 열수 추출한 인삼추출액의 첨가량을 달리하여 저온압출공정으로 제조한 구형과립의 입자분포, 마모율, 용적밀도, 진동밀도, 압축지수와 용출패턴을 결정하였다. 열수추출수율에서 수삼을 압출성형할 때 수분함량이 가장 유의적으로 영향을 미쳤다. 수분함량의 감소와 함께 스크류 회전속도가 증가할수록 압출성형 수삼의 추출수율이 크게 증가하였다. 추출수율이 최대가 되는 압출성형 공정변수는 수분함량 15%, 스크류 회전속도 250 rpm, 사출구 부위온도 13$0^{\circ}C$였다. 동일한 추출조건에서 15개 압출성형 수삼 시료의 평균 추출수율(43.5%)은 홍삼(38.3%)과 백삼(29.0%) 추출수율과 비교하여 크게 향상되었다. 저온압출공정으로 압출성형 수삼농축액(고형분함량 59.2%)의 농도를 5, 20, 30, 40, 50, 60%로 각각 증류수에 희석한 용액 200 mL과 200 g 미세결정 셀룰로오즈를 이용하여 과립화시킬 수 있는 압출성형 수삼추출액의 최대 농도는 60%였으며 추출액의 증가와 함께 입자수율의 증가, 마모율의 감소, 압출지수의 감소 등으로 입자의 물리적 특성은 구형과립을 젤라틴 캡슐에 포장하여 제품화할 수 있었다. 또한 압출성형 수삼 추출액을 포함한 구형과립으로부터 농축액 성분이 10분 이내에 쉽게 용출되므로 구형과립은 젤라틴 캡슐에 적합하다는 결론을 내릴 수가 있었다.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2012년도 춘계학술대회 논문집
• /
• pp.1217-1218
• /
• 2012

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1997년도 춘계학술대회 논문집
• /
• pp.584-588
• /
• 1997

Lots of forginfs used in automobile and aerospce industries are made in hot or cold working conditions, depending on the size and shape of a product. Usually the die design for new items has been first made on the basis of experiences and many know-hows accumulated in the company and then slightly modified through trial and error method to get the desired forgings without defects. Most of drawings at the die design stage have been manually drawn, butrecently some of forging companies have begun to apply a computer-aided drafting technique to the die design for reducing drafting time as well as repeatedly utilizing standardized parts form registerd data base. In this paper the automated die design technique for forward extrusion of axisymmetric forgings is developed by using AutoLISP language. For this study the representative die system is determined form the investigation of several types of forging dies being currently employed in the metal forming field and the design rules for cold extrusion die are summarized and programmed on a personal computer. A few design examples of forward extrusion die are given and discusses.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2003년도 춘계학술대회 논문집
• /
• pp.1382-1385
• /
• 2003

Deformation on shapes of the hydrogen absorption metal in this paper was investigated on hydrogen absorption-desorption cycling. In order to study this problem, the cold rolled palladium plate and the cold extrusion palladium bar as specimens had been used. By using the electrochemical method, the palladium specimens were cyclically hydrogenated in the 0.1 mol H$_2$SO$_4$ electrolyte. As results, it is noted that the thickness of the plate specimen gradually increased in increasing hydrogenation cycles whereas the width and the length decreased. But both the diameter and the length of the bar specimen increased with increasing hydrogenation cycles. Also, grains in the plate specimen were greatly deformed after hydrogenation cycling whereas internal grains in the bar specimen were pulverized. And deterioration of the hydrogen absorption rate of the bar specimen was lager than the plate specimen.

• 소성∙가공
• /
• 제23권4호
• /
• pp.221-230
• /
• 2014

This study deals with a series of experimental investigations on multi-stage cold forging of an outer race used for a constant velocity (CV) joint with six inner ball grooves. The multi-stage cold forging, which consists of forward extrusion, upsetting, backward extrusion, and combined sizing-necking including ironing, was used to produce a prototype of the outer race. The cold forging tools such as forging punches and dies required in this multi-stage cold forging were also designed and fabricated. For the combined sizing-necking, especially, the longitudinally six-segmentallized punches were developed to easily eject from the necked inner groove of the outer race with consideration of the operating mechanism. Spheroidized SCr420H billet was used in the experimental study. To verify the suitability of the proposed process, the obtained parts were obtained from each forging operation, and the geometries were compared with the target dimensions. It was confirmed that the outer race with six inner ball grooves was well forged by adopting the proposed multi-stage cold forging, and the dimensional accuracy of the forged outer race matched well with the requirements.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2003년도 The 8th Asian Symposium on Precision Forging ASPF
• /
• pp.51-54
• /
• 2003

Internal defects such as chevron crack occasionally occur in the process of cold extrusion or cold drawing. It is known that the existence and property of inclusion greatly influences the generation of the internal crack. However, in the plastic working field, research about the effect of the inclusion on the fracture is not theoretically analyzed. This paper describes effects of the physical property of inclusion on the internal fracture generation in the process. Prediction of fracture was evaluated by critical damage value calculated by the equation of Cockcroft & Latham and its change by the inclusion physical property such as size and stiffness was investigated.