• International Journal of Precision Engineering and Manufacturing
• /
• 제1권1호
• /
• pp.152-159
• /
• 2000

In piercing operation for small hole in very thin plate, micro burrs are formed. The micro burr is very difficult to remove because the thin plate is to be deformed during deburring and deteriorate accuracy. As a first step to remove the micro burrs effectively, the burr must be measured accurately as much as possible. For most micro burrs are so small as less than 10$\mu\textrm{m}$, it is very difficult to measure. Several methods are reviewed to measure the micro burr formed in piercing operation from very thin plate with thickness less than 0.1mm. Also the effective deburring methods are reviewed. Barreling ultrasonic and chemical deburring methods are performed and the results are compared.

• Journal of Welding and Joining
• /
• 제33권3호
• /
• pp.75-80
• /
• 2015

Self-piercing riveting is an joining method of advanced high strength steels (AHSS) and other dissimilar materials. It has attracted considerable interest from the automotive industry. The SPR has become an interesting alternative joining technique for difficult to weld materials such as steels and aluminium alloys. In this paper, self-piercing rivet and anvil for SPR were designed for the joining conditions with AHSS and aluminium alloy. Various conditions of SPR were simulated for the design of rivets and anvils. The simulated results were in good agreement with experimental ones. As a result, over HV500 rivet is desirable to joint SPFC780 AHSS and aluminum alloy.

• 대한기계학회논문집A
• /
• 제28권7호
• /
• pp.992-998
• /
• 2004

During the tube hydropiercing, the region adjacent to the pierced hole will be deformed and will be drawn away from the die block as the punch advances through the wall of the tube. The deformation in the region may range from a substantially flat form to a countersunk form, so called rollover. In this study, the effects of material properties, shape of piercing punches, roundness of tube surface and internal pressure within the tube during piercing on the rollover have been investigated experimentally. The results provide the quantitative variation of rollover at given hydropiercing parameters, and a relationship between the deformed radius and the rollover caused by the deformation has been established.

• 소성∙가공
• /
• 제13권2호
• /
• pp.154-159
• /
• 2004

Deformation surrounding the hole in the tube during the hydropiercing process has been investigated in this study. The tube is expanded and internally pressurized between upper and lower dies, and a piercing punch is driven forcefully through a cross passage in the die and through the wall of the tube. The pressurized fluid within the tube provides support to the wall of the tube during a piercing step to form a hole in the tube having less deformation surrounding the hole in the tube. The deformation area may be fully retracted to a substantially flat form or partially retracted to a countersunk form. In this study, a mathematical model that can predict deformation surrounding the hole has been proposed and experimentally verified by actual hydropiercing test.

• 소성∙가공
• /
• 제8권2호
• /
• pp.216-221
• /
• 1999

In this paper, an application-oriented approach to piercing analysis in automatic forging simulation by the rigid-viscoplastic finite element mehtod is presented. In the presented approach, the accumulated damage is traced and the piercing instant is determined when the accumulated damage reaches the critical damage value. A method of obtaining the critical damage value by comparing the tensile test result with the analysis one is given. The presented approach is verified by experiments and applied to automatic simulation of a sequence of 6-stage forging processes.

• 소성∙가공
• /
• 제21권1호
• /
• pp.19-23
• /
• 2012

In this paper, a Mannesmann roll piercing process equipped with Diecher's guiding discs is investigated using a rigid-thermoviscoplastic finite elements method with intelligent remeshing capability and tetrahedral elements. The analysis model is presented and the approach is applied to a Mannesmann roll piercing process found in the literature. Details about the remeshing criterion as well as mesh density control are given. The present predictions are compared with the predictions found in the literature, showing that the two predictions are in close agreement in terms of the deformed shape. However, it is emphasized that the present approach has the distinct strength in predicting details of final shape.

• Journal of Welding and Joining
• /
• 제34권1호
• /
• pp.59-67
• /
• 2016

The automotive manufactures increase their use of lightweight materials to improve fuel economy and energy usage has a significant influence on the choice of developing materials. To meet this requirements manufacturers are replacing individual body parts with lightweight metals, for these the process treating and painting surfaces is changing. The pre-coated steels are newly developed to avoid the conventional complex and non-environmental painting process in the body-in-white car manufacturing. The development of new joining techniques is critically needed for pre-coated steel sheets, which are electrically non-conductive materials. In the present study, dissimilar combination of pre-coated steel and galvanized steel sheets were joined by the self-piercing rivet, adhesive bonding and hybrid joining techniques. The tensile shear test and free falling high speed crash test were conducted to evaluate the mechanical properties of the joints. The highest tensile peak load with large deformation was observed for the hybrid joining process which has attained 48% higher than the self-piercing rivet. Moreover, the hybrid and adhesive joints were observed better strain energy compared to self-piercing rivet. The fractography analyses were revealed that the mixed mode of cohesive and interfacial fracture for both the hybrid and adhesive bonding joints.

• 대한조선학회논문집
• /
• 제52권6호
• /
• pp.485-493
• /
• 2015

Planing hull form is widely used as a high speed vessel hull. There is a problem of the planing hull not solved yet. The problem is that the planing hull has very large vertical acceleration and large heave and pitch motions. As one method for overcoming this problem, there is "wave-piercing hull". Before the motion in waves is investigated, the resistance and running attitude must be investigated. In this paper, the running attitude and resistance of two wave-piercing hulls are investigated by model tests. Model test results show that the wave-piercing hulls have large trim angle and sinkage at the high speed, so additional model tests are conducted by using the hull appended by stern interceptor that is very thin plate to increase the hydrodynamic pressure at the attached location. The results are compared with other planing hulls and the resistance components and the hydrodynamic force are discussed. From the model test results, it can be known that the stern interceptor is the effective appendage for the reduction of the resistance and trim angle of wave-piercing hull.

• 한국응용곤충학회지
• /
• 제27권2호
• /
• pp.111-116
• /
• 1988

1987년 6월부터 9월가지 경남 진주지방의 복숭아, 자두, 배가 심어져 있는 사지 과수원에서 4개의 black light(BL) trap과 야간에 1시간 동안(22시~23시)의 포충망채집에 의하여 흡수나방의 종류를 조사한 결과는 다음과 같다. 두가지 채집방법으로 의해 15종의 1차가해종과 22종의 2차가해종 및 가해습성으르 알 수 없는 4종 등 총 41종의 흡수나방이 조사되었으며, 이 중에서 16종은 우리나라에서 흡수나방으로처음 보고되는 종류이다. 1차가해종의 우점종은 작은갈고리밤나방, 무궁화밤나방, 스투포사밤나방, 금빛우묵밤나방, 갈고리밤나방으로서 전체의 86.7%를 차지하였다. 2차가해종의 우점종은 검거세미나방, 쌍띠밤나방, 까마귀밤나방, 세줄박각시나방으로서 전체의 80.5%를 차지하였다. BL trap으로는 총 채집수 15.2%가, 야간포충망채집으로는 79.7%가 1차가해종이었다. 무궁화밤나방, 스투포사밤나방, 작은갈고리밤나방은 복숭아, 자두, 배에서 공히 많이 채집되었으며 그외에 복숭아에서는 갈고리밤나방, 자두에서는 금빛추묵밤나방, 배에서는 태극나방이 많이 채집되었다.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2011년도 춘계학술대회 논문집
• /
• pp.1321-1322
• /
• 2011