Yoshifumi Ohbuchi

Chipping in High-Precision Slot Grinding of Mn-Zn Ferrite

High-precision slot grinding was carried out on Mn-Zn ferrites to investigate the chipping mechanism and optimum slotting condition by measuring the chipping size at the slotted edges. The slot grinding was performed using a high-precision slicing machine with an air spindle and different type of 2mm wide diamond wheels. The size (width, length) of all chippings was measured by a specially designed form tracer with a knife edge pickup. Grinding forces were also measured. It is evident that chipping size depends on removal per grain and some ductile fracture modes are observed at lower removal rate ranges. Therefore, chipping size can be reduced largely by decreasing removal per grain.

Warp in High Precision Cut-Off Grinding of Al2O3-TiC Ceramic Thin Plate

Abstract High precision cut-off grinding has been carried out on Al 2 O 3 -TiC ceramic thin plates with metal bond thin diamond wheels. The warp of the cut-part as well as the flatness of work surface, i.e. deflection of wheel, was precisely measured and thus, the warp generation mechanism was analyzed and the optimum slicing condition was investigated. Grinding forces were measured for discussing the warp. Also, the effect of V-shaped guide groove for depressing the deflection was studied. It is evident that the warp of workpiece and the wheel deflection largely depend on grinding type and pre-processing conditions. The high feed cut-off grinding is most effective for restraining the deflection, and the use of a V-shaped groove is a useful way to depress the deflection

Thermal image analysis of plastic deformation and fracture behavior by a thermo-video measurement system

The visualization of the plastic region and the measurement of its size are necessary and indispensable to evaluate the deformation and fracture behavior of a material. In order to evaluate the plastic deformation and fracture behavior in a structural member with some flaws, the authors paid attention to the surface temperature which is generated by plastic strain energy. The visualization of the plastic deformation was developed by analyzing the relationship between the extension of the plastic deformation range and the surface temperature distribution, which was obtained by an infrared thermo-video system. Furthermore, FEM elasto-plastic analysis was carried out with the experiment, and the effectiveness of this non-contact measurement system of the plastic deformation and fracture process by a thermography system was discussed. The evaluation method using an infrared imaging device proposed in this research has a feature which does not exist in the current evaluation method, i.e. the heat distribution on the surface of the material has been measured widely by noncontact at 2D at high speed. The new measuring technique proposed here can measure the macroscopic plastic deformation distribution on the material surface widely and precisely as a 2D image, and at high speed, by calculation from the heat generation and the heat propagation distribution.

Application of New Design Method by High-Strength Composite Material

The purpose of this study is to apply a new design method, which integrates both optimum strength and product design. Here, the collaboration of design and strength by using composite materials is administered. Many products, which are made from high strength composite materials, require new product design technology. Existing product developments tend to separate product design from product planning. The process begins from planning the shape of the product, then calculating the strength, and lastly designing the product. In our new design method, we create from an engineering point of view. By using a design method of high-strength materials, we designed a new ZIGZAG CHAIR made of carbon fiber reinforced plastic of excellent strength and light-weight.

Application and Evaluation of New Design Method by Using Carbon Fiber-Reinforced Plastics

This research is the application of new design method for integrating the optimum shape and strength design process. The products is manufactured from product design which can use the advanced characteristic of composite materials obtained by the experiment and the numerical analysis. Here, the collaboration of the design and the strength analysis by using composite materials is carried out. The products, which are made from high strength composite materials, need new product design technology which draws out the characteristic of materials advantage. Existing product developments tend to separate product design from product planning. The process consists of three stages as follows; 1) Planning the shape of the product by designers, 2) Calculating the strength by numerical analysis, 3) Designing the product. It is performed a styling design by requirements from the engineering point of view. By using this design method of high-strength materials, we designed new styling ZIGZAG Chair made of the carbon fiber reinforced plastic with excellent strength and lightweight.

Development and Application of New Design Method by High-Strength Composite Material - Fusing of Optimum Strength Evaluation and Product Design

The purpose of this research is the development of new design method for integrating the optimum strength evaluation and the product design which can make the best use of materials characteristics obtained by the experiment and the analysis. Further we do design using high-strength composite material with this developed concept which is different from conventional design. First, to establish this design method of high-strength materials, we examined these materials characteristics and manufacturing methods and the commercialized products. As this research target material, we focus the fiber reinforced materials such as composite with carbon fiber, glass fiber and aramid fiber. Above all, we marked the carbon fiber which has the high specific tensile strength, wear resistance, heat conductivity and conductance. Here, we introduce the fundamental design concept which makes the best use of the design with enough strength.

Evaluation of Plastic Deformation and Fracture Behaviors by Thermal Image Technique

Failure of mechanical members largely depends on the size and the development of plastic deformation from the strain concentration parts. In order to evaluate this plastic deformation of mechanical members, we pay attention to the surface temperature that is generated by plastic deformation. Most of the plastic energy exhausted by plastic deforming is converted into heat. Therefore, the heat generation represents the macroscopic plastic deformed intensity. In this report, the tensile deformation tests by using the plate specimen with a center crack were performed and the distributions of surface temperature under the plastic deformation and crack propagation were measured by the thermocouple and the infrared thermo camera. Furthermore, FE elasto-plastic analysis couples with transient heat conduction was performed. The analytical results were good agreement with the experimental ones and it was shown that the infrared thermography method was effective non-contact measurement system as the macroscopic evaluation of the plastic deformation.

Deep Drawing Formability Analysis of AZ31 Mg-Alloy

Light and highly resistant, magnesium has been more and more included into alloys composition, especially in automotive and electronic devices. Usual automotive applications for magnesium alloys are gearbox, cylinder head covers and other types of covers, when electronic industry uses this alloys for mobile computers and mobile phones frames (chassis). However casting is still the first production process for magnesium application, press forming is considered as having significant potential. Yet, influences of many key parameters are not clearly known. In this report, sheets of AZ31 magnesium alloy were submit to deep drawing tests to investigate the influence of temperature, lubricant, blank holding pressure and speed. As a result, an appropriate lubricant was selected out of a set of potentially interesting lubricants selected with respect to their announced properties. Deep drawing tests also enlighten the poor formability of AZ31 even at 160°C and an apparent optimum formability temperature at 200°C. Other tests and controls, like thickness profile, were also performed to complete knowledge of AZ31 properties.

Electromyogram signal processing by using M-transform

The authors propose a new method for reducing both impulsive noise and white noise by use of M-transform and wavelet shrinkage. M-transform is a new signal transformation proposed by the authors, and any periodic time signal can be considered as the output of a filter whose input is an M-sequence. By using the properties of M-transform, it is shown that both impulsive noise and white noise can be eliminated by use of first M-transform and then wavelet shrinkage. In this paper, the proposed noise reduction method is applied to the electromyogram signal which sometimes contains many impulsive noise and white noise. From the results of the experiment, it is shown that the proposed method is very efficient for impulsive noise reduction.

Development of Gun Bullet Protect Board - Gun Bullet Experiment and Analysis -

The purpose of this study is development of gun-bullet protect board. The collision test was executed in such a way to launch a bullet and collide to the target by the air gun. The mock bullet made of brass was used as the projectile. The collision behaviors of polycarbonate (PC) target board were clarified. Next, the analysis of gun bullet collision between the bullet and PC board has been practiced by non-liner dynamic FEM commercial software (AUTODYNTM) and an effective bullet protection board is designed based on this analytical result.