Jong Deok Kim

A Comparative Study of Failure Criteria for Magnesium Alloy Sheet under Warm Press Forming Condition

Magnesium sheet alloys possess limited plastic formability at room temperature but their formability is substantially improved at elevated temperatures and optimum strain rates. In the present paper, three different types of failure criteria, namely, strain-based, stress-based, and work-based criteria, are compared for their applicability to warm press forming of magnesium sheet alloys. Warm deep-drawing experiments were conducted on AZ31 alloy sheet, and the results were used to assess the strength and weakness of the failure criteria.

An Experimental Study of V-Ring Position on the Die Roll Height in the Fine Blanking of Special Part with Corner Shapes

In this paper, the relation between die roll height and V-ring position of a fine blanking tool was studied by experimenting on a special part with various corner shapes. Three guide plate inserts with different V-ring positions and a die insert with constant die chamfer were machined, and a fine blanking tool was manufactured for the fine blanking experiments. Three experiments were conducted on a 650-ton fine blanking press. Each die roll height was measured and analyzed. We found the tendency of the die roll heights on the corner shapes of fine blanked parts to increase with increasing the distance between the V-ring position and the contour of the special part, and to decrease with increasing corner radius and angle. These results can be used to minimize the die roll height of fine blanking parts with corner shapes when designing the V-ring of a fine blanking tool.

A study on the change of die roll size by the shape of die chamfer in fine blanking die for automobile door latch

Abstract There is always die roll in fine blanking parts which is able to have 100% clean shear surface. In this paper the change of die roll size was studied by fine blanking tryout in order to minimize die roll size. Various die inserts with different die chamfer were machined, fine blanking die was manufactured and tested. The die roll sizes of fine blanking samples were measured and the tendency of thickness directional die roll size was comprehended. This result will be used on the design of die chamfer in order to minimize thickness directional die roll size of fine blanking partsKey Words : Fine blanking, Die roll, Die chamfer, Die insert, Punch 본 논문은 지식경제부의 자동차 핵심 부품 생산 기반 공정 플랫폼 기술 개발 사업(과제번호 : 10-FM-2-0038)의 연구 과제로 수행되었음. * 교신저자 : 김종덕(jdk@kitech.re.kr)접수일 11년 01월 03일 수정일 (1차 11년 02월 08일, 2차 11년 02월 09일) 게재확정일 11년 02월 10일 1. 서론 파인 블랭킹(이하 FB)은 1 회의 블랭킹에서 제품의 전체 두께에 걸쳐 필요로 하는 고운 전단면과 양호한 제품 정밀도를 얻는 프레스 가공 공정으로 더 이상의 기계 가공이 필요 없다. 일반적으로 FB 기술이 적용되는 제품은 사용 목적상 일반 프레스에서 블랭킹 가공할 경우 후속 공정이 많아져 경제성이 없기 때문에 후판 제품(두께 0.5 - 20mm)에 많이 적용되고 있다. 따라서 FB 제품은 주로 자동차의 기능 부품, 전기전자 구조 부품, 일반 기계요소 등과 같이 제품의 정밀도와 절단면의 품질이 동시에 요구되는 후판 제품에 적용된다. FB 제품은 그림 1과 같이 전단 과정이 3 단의 복합 운동 프레스에서 재료를 완전히 클램핑한 상태에서 전단하고 특히 펀치와 다이 사이의 간극(clearance)이 제품 두께의 약 0.5%를 유지하므로 전체 두께의 절단면에 걸쳐 매끄러운 전단면을 얻을 수 있으며, 표면 거칠기는 재료의 두께에 따라 일반 기계 가공에서 얻을 수 있는 Ra 0.4 -16

Finite-Element Analysis of Warm Square Cup Deep Drawing Process of Magnesium Alloy AZ31 Sheet

Magnesium alloys are expected to be widely used fur the parts of structural and electronic appliances due to their lightweight and EMI shielding characteristics. While the die casting has been mainly used to manufacture the parts from the magnesium alloys, the press forming is considered as an alternative to the die casting for saving the manufacturing cost and improving the structural strength of the magnesium alloy parts. However, the magnesium alloy has low formability at room temperature and therefore, in many cases, forming at elevated temperatures is necessary to obtain the required material flow without failure. In the present study, square cup deep drawing tests using the magnesium alloy AZ31 sheet were experimentally conducted at various elevated temperatures as well as room temperature, and the corresponding finite-element simulations, which calculated the damage evolution based on the Oyane`s criterion, were conducted using the stress-strain relations from the tensile tests at various temperatures. The formability predictability by the finite-element analysis was investigated by comparing the predicted damage distributions over the deformed AZ31 sheet at elevated temperatures with the corresponding experimental deformations with failures.

A Progressive Fine Blanking Process Design for Forming of Carrier Plate

Blanking process is widely used fur producing various structural parts. However, fine blanking technology is frequently used as a single step blanking operation with clean cut surface of a sheared surface because the fractured surface of parts causes serious problems in the final product and therefore it must be removed by the post-processing in case of the conventional blanking. In the present investigation, a fine blanking process was designed within the framework of progressive die to produce a carrier plate assembled within the auto transmission. Finite element analysis of the shearing behavior at the respective stage of the progressive fine blanking was conducted to validate the designed die parameters. Finally the designed progressive fine blanking process was experimentally evaluated by using the machined die.

An Experimental Study on the Effect of Die Chamfer Shape and V-Ring Position on Die Roll Height in the Fine Blanking of a Special Part with Various Corner Shapes

In this paper, a change of die roll height according to the die chamfer shape and V-ring distance of a fine blanking tool was studied by experiments on a special part with various corner shapes. Three guide plate inserts with different V-ring positions and three die inserts with different die chamfers were machined, and then a fine blanking tool was manufactured for the fine blanking experiments. Nine experiments were conducted on a 650-ton fine blanking press. Each die roll height was measured and analyzed. It would be noticed that the die roll heights on the corner shapes of the fine blanked parts increased with increasing V-ring distance and die chamfer angle, but it decreased with increasing corner radius and angle. The results in this study can be used to minimize the die roll height of fine blanked parts with corner shapes when designing the V-ring and die chamfer of a fine blanking tool.

An Experimental Study of Injection Molding for Multi-beam Sensing Lens Using The Change of Gate Geometry

Abstract Rapidly developing IT technologies in recent years have raised the demands for high-precision optical lenses used for sensors, digital cameras, cell phones and optical storage media. Many techniques are required to manufacturing high-precision optical lenses, including multi-beam sensing lenses investigated in the current study. In the case of injection molding for thick lenses, a shrinkage phenomenon often occurs during the process. This shrinkage is known to be the main reason for the lower optical quality of the lenses. In the present work, a CAE analysis was conducted simultaneously with experiments to understand and minimize this phenomenon. In particular, the sectional area of a gate was varied in order to understand the effects of packing and cooling processes on the final shrinkage pattern. As a result of this study, it was demonstrated that a dramatic reduction of the shrinkage could be obtained by increasing the width of the gate. Key Words : Injection Molding, Optical Lens, Multi-beam Sensor, Shrinkage, Packing

A Study on Die Roll Height of Special Automobile Seat Recliner Gear According to Die Chamfer Shape in Fine Blanking Tool

In this paper, the effect of die chamfer shape on the die roll height was studied by fine blanking experiments for imaginary special automobile seat recliner gear. The three die inserts with different die chamfer shapes were machined, and fine blanking tool was manufactured. Using the fine blanking tool, three experiments were conducted on the 650 ton fine blanking press. Each die roll height was measured, analyzed and we found the tendency of die roll heights on imaginary special automobile seat recliner gear to increase with increasing die chamfer angle, with the horizontal distance of die chamfer being constant. This result can be used to minimize the die roll height of fine blanking gear parts when designing die chamfer of fine blanking tool.

A Study on the Relation between Die Roll Height and Die Chamfer Shape in Fine Blanking for Special Gear

In this paper, the relation between die roll height and die chamfer shape was studied by fine blanking experiments for imaginary special gear. The three die inserts with different die chamfer shapes were machined, and fine blanking tool was manufactured. Using the fine blanking tool, three experiments were conducted on the 650 ton fine blanking press. Each die roll height was measured, analyzed and we found the tendency of die roll heights on imaginary special gear to increase with increasing die chamfer angle, with the horizontal distance of die chamfer being constant. This result can be used to minimize the die roll height of fine blanking gear parts when designing die chamfer of fine blanking tool.

A Study on the Effect of V-Ring Position on the Die Roll Height in Fine Blanking for Special Automobile Seat Recliner Gear

In this paper, the relation between die roll height and V-ring position was studied by fine blanking experiments for imaginary special automobile seat recliner gear. The three die inserts and three guide plate inserts with different V-ring positions were machined, and fine blanking tool was manufactured. Using the fine blanking tool, three experiments were conducted on the 650 ton fine blanking press. Each die roll height was measured, analyzed and we found the tendency of die roll heights on imaginary special gear to increase with increasing the distance between V-ring position and contour of gear. This result can be used to minimize the die roll height of fine blanking gear parts when designing V-ring of fine blanking tool.