Yong-Phil Jeon

Evaluation of the formability of a bipolar plate manufactured from aluminum alloy Al 1050 using the rubber pad forming process

The rubber pad forming process has been used to fabricate metallic bipolar plates from aluminum 1050 alloy for use in a proton-exchange membrane fuel cell. The plates were fabricated using a 200 ton hydraulic press and the effects of the process parameters of the rubber pad forming process (plate thickness, punch speed, press pressure, rubber thickness and rubber hardness) on the forming depth and thinning were evaluated.

Effect of stamping load variation on deformation behaviour of stainless steel thin plate with microchannel

A thin plate like a bipolar plate for a proton exchange membrane fuel cell is one of the core parts for improving the power density in a fuel cell. Stainless steel has excellent characteristics in terms of electrical resistivity, density, and thermal conductivity. Furthermore, stainless steel, instead of graphite, is used as a bipolar plate because it is cheaper and easier to machine. Therefore, in this study, a stainless steel alloy is selected as the ideal material for a bipolar plate. In this article, the results of feasibility experiments are presented; these experiments are performed with the aim of developing fuel cells using stainless steel bipolar plates with multiple channels. In this investigation, a dynamic load was applied, and the formability of microchannels was estimated with different punch pressures and die roundness, using a thin sheet metal of SUS304 with thicknesses of 0.3 and 0.1 mm. In the case of the die roundness of 0.1 mm, the formability is optimized with a sine wave dynamic load that has 90 kN of maximum pressure and five cycles of punch movement. The experimental results demonstrate the feasibility of the proposed manufacturing technique for fabricating bipolar plates.

Assessment of die material manufactured using the lost foam casting process for hot press forming

The lost foam casting process for the manufacture of press dies has attracted a lot of attention because of various advantages, such as the small number of processes involved and the reduction in the cost of die production. In a recent study, tensile tests were conducted to analyze the casting defects of ductile cast iron, study the wear of as-cast and heated cast iron, and investigate the use of AISI H13 as a tool material for die casting. However, the most commonly used material for hot press forming is the forged tool steel AISI H13, which has excellent thermal resistance. In spite of the abovementioned advantages of die materials fabricated by lost foam casting, which arise from the near net shape design of the die, no study has been conducted on the use of the heat-treated H13 cast material for hot press forming dies. In this study, impact, machinability, tensile, and wear tests were conducted at high temperatures, and the properties of the heat-treated H13 cast material and the heat-treated H13 forged material were compared.

Experimental Assessment of High Temperature Formability of Boron Steel Sheet Manufactured With a Spring Compound Bending Die

Bending behavior occurs in the hot press forming process, resulting in many cases of failure during forming. To address the problem of cracking and improve the formability and mechanical properties of boron steel sheets in the bending process, an experiment has been carried out by using a spring compound bending die. Also, a comparison has been made between the traditional U-bending die and the spring compound bending die with regard to formability. The influence of the parameters for hot press forming such as the heating temperature, punch speed, and die radii on the mechanical properties and microstructure was analyzed by tension testing and metallographic observations.

Effect of sheet-metal thickness and hardness on the life cycle and sliding force of a novel ultraslim spring unit for a semi-automatic sliding mechanism used in IT devices

Great strides made in the industries manufacturing components for IT devices have facilitated the development of cellular phones that are either similar in size or smaller than previously existing phones. In addition, the functions carried out by devices such as MP3 players, digital cameras, and GPS devices are now being incorporated into cellular phone, the quintessential IT device. However, there are limitations on the extent to which the sizes of the components can be reduced due to technical reasons pertaining to mechanical and/or electrical properties, the manufacturing process, and the structure of the assembly. In addition, more emphasis than ever is being placed on the design of a cellular phone as it has come to be regarded as a necessity; thus, like an accessory, it needs to be stylish, highly mobile, and portable, regardless of advances in technology. To develop phones that meet these requirements, the thickness and degree of design freedom have to be reduced and improved, respectively. With this in mind, we propose a novel spring unit for the slide mechanism of a cellular phone as a practical alternative not only for maintaining the mobility and portability of the phone, but also for increasing competitiveness as this component helps to reduce the thickness of the phone. In addition, it provides a degree of freedom that allows other hardware components in the phone to be placed and adjusted more freely than conventional spring units built for the same purpose. Experiments conducted indicate that the life cycles and sliding forces of our proposed spring can be easily set by merely controlling the thickness and hardness of the sheet metal plate used for fabricating the spring. Furthermore, our proposed spring can be used to further reduce the thickness of the existing IT devices while preserving their performance and reliability. We believe that our etching process using heat-treated sheet metal can be widely applied to fabricate springs for various applications that require minimized thickness.