Numerical Analysis of Temperature Distribution and Its Optimization for Thin Foils in Micro Deep Drawing Assisted by Resistance Heating

2015 ◽  
Vol 86 (8) ◽  
pp. 869-876 ◽  
Author(s):  
Qiu Zheng ◽  
Tetsuhide Shimizu ◽  
Ming Yang
2011 ◽  
Vol 473 ◽  
pp. 1008-1015 ◽  
Author(s):  
Zhen Yu Hu ◽  
Hanna Wielage ◽  
Frank Vollertsen

Due to size effects new challenges are involved in micro deep drawing compared to macro deep drawing. One of these challenges is that the limit drawing ratio in micro deep drawing becomes smaller than that in macro forming, which limits the application potential of micro deep drawing in an industrial context. In order to extend the application possibilities of micro deep drawing, investigations were carried out on this topic. Own previous work showed that the “tribological effect”, the “global flow behaviour effect” and the “local flow behaviour effect” are responsible for the lower forming limit in the micro range. In this paper, the flow behavior of thin foils is further investigated. Forming limit diagrams of Al99.5 and E-Cu foils with different thicknesses ranging from 20 μm to 100 μm were acquired using an optical measurement system. It was found that the forming limit of thin foils is lower than that of thicker foils. Further analysis indicates that this difference is due to the number of grains in the direction of thickness of the material: more grains give more grain boundaries, which allows more strain of the grains.


2021 ◽  
Vol 34 (1) ◽  
Author(s):  
Jingwei Zhao ◽  
Tao Wang ◽  
Fanghui Jia ◽  
Zhou Li ◽  
Cunlong Zhou ◽  
...  

AbstractIn the present work, austenitic stainless steel (ASS) 304 foils with a thickness of 50 µm were first annealed at temperatures ranging from 700 to 1100 ℃ for 1 h to obtain different microstructural characteristics. Then the effects of microstructural characteristics on the formability of ASS 304 foils and the quality of drawn cups using micro deep drawing (MDD) were studied, and the mechanism involved was discussed. The results show that the as-received ASS 304 foil has a poor formability and cannot be used to form a cup using MDD. Serious wrinkling problem occurs on the drawn cup, and the height profile distribution on the mouth and the symmetry of the drawn cup is quite non-uniform when the annealing temperature is 700 ℃. At annealing temperatures of 900 and 950 ℃, the drawn cups are both characterized with very few wrinkles, and the distribution of height profile, symmetry and mouth thickness are uniform on the mouths of the drawn cups. The wrinkling becomes increasingly significant with a further increase of annealing temperature from 950 to 1100 ℃. The optimal annealing temperatures obtained in this study are 900 and 950 ℃ for reducing the generation of wrinkling, and therefore improving the quality of drawn cups. With non-optimized microstructure, the distribution of the compressive stress in the circumferential direction of the drawn foils becomes inhomogeneous, which is thought to be the cause of the occurrence of localized deformation till wrinkling during MDD.


2013 ◽  
Vol 46 (3) ◽  
pp. 201-208 ◽  
Author(s):  
Sooseok Choi ◽  
TianMing Li ◽  
Takayuki Watanabe ◽  
Takashi Nakayama ◽  
Koji Otsuki

2014 ◽  
Vol 622-623 ◽  
pp. 201-206 ◽  
Author(s):  
Kenichiro Mori ◽  
Tomoyoshi Maeno ◽  
Shohei Nakamoto

A hot spline forming process of die-quenched gear drums using resistance heating of a side wall of a cup formed by cold deep drawing and ironing was developed. The side wall having uniform cross-sectional area is resistance-heated by passage of the current in the axial direction, the heated side wall of the drawn cup is ironed and is finally die-quenched. The gear drum was successfully formed and the hardness was between 400 and 500 HV. Not only the formability was improved but also the formed dram was hardly oxidised because of rapid resistance heating.


2016 ◽  
Vol 51 (18) ◽  
pp. 2575-2583 ◽  
Author(s):  
Mahdi Ashrafi ◽  
Brandon P Smith ◽  
Santosh Devasia ◽  
Mark E Tuttle

Composite scarf repairs were cured using heat generated by passing an electrical current through a woven graphite-epoxy prepreg embedded in the bondline. Resistance heating using the embedded prepreg resulted in a more uniform temperature distribution in the bondline while preventing any potential thermal damage to the surface of the scarf repairs. In contrast, conventional surface heating methods such as heat blankets or heat lamps lead to large through thickness thermal gradient that causes non-uniform temperature in the bondline and overheating the outer surface adjacent to the heater. Composite scarf repair specimens were created using the proposed embedded heating approach and through the use of a heat blanket for circular and rectangular scarf configurations. Tensile tests were performed for rectangular scarf specimens, and it was shown that the bond strengths of all specimens were found to be comparable. The proposed embedded curing technique results in bond strengths that equal or exceed those achieved with external heating and avoids overheating the surface of the scarf repairs.


2021 ◽  
Vol 2020 (1) ◽  
pp. 012040
Author(s):  
S N Yuan ◽  
H B Xie ◽  
F H Jia ◽  
H Wu ◽  
D Pan ◽  
...  

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