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Featured researches published by Koichi Funabashi.


Tribology International | 1992

Mechanism and optimum shape of knife edge for metal sealing

Y. Matsuzaki; K. Hosokawa; Koichi Funabashi

Abstract The contacting state of knife-edge seals was investigated and a new type of knife edge was developed. The contacting state of knife-edge seals was divided into three types according to the apex width of the knife edge: (a) penetration type, (b) indentation type, and (c) intermediate type. The developed knife edge had a contacting state of penetration type (a). Because of the narrow apex width of the knife edge, the values of Pc/l for the compressive forces per unit length required for sealing were lower than those of other types of knife-edge seals. The contact pressure required for sealing was nearly equal to the Meyers hardness in the sealing surface layer, regardless of the surface roughness in turning. The optimum shape of the knife edge was of type (a) and had a ridge in a V-shaped cross-section with a plane inclined 30° off normal and the flat area of its apex finished by lapping was about 35 μm wide. The knife edge made of hard material with optimum shape could be utilized in the cases where the sealing materials were copper, carbon steel and stainless steel, and the values of Pc/l were approximately 15–40, 45–110 and 80–190 kN m−1, respectively.


Wear | 1987

Microscopic normal displacement of contacting bodies with tangential load

Koichi Funabashi; Takashi Nakamura

Abstract Normal microdisplacements of contacting bodies caused by applying a tangential load are investigated in this study. A new method to calculate the normal microdisplacement of an actual contacting surface was introduced and the calculated results were compared with the experimental results obtained for sand-blasted surfaces. Experiments and calculations were carried out for the following three cases: 1. (1) rigid surface asperities penetrating a mating plastic material; 2. (2) surface asperities plastically compressed by a flat anvil; 3. (3) asperities made of the same plastic material as the mating flat surface.


Transactions of the Japan Society of Mechanical Engineers. C | 1992

Sealing Characteristics of an Annular Wedge-Shaped Gasket.

Yoshio Matsuzaki; Koichi Funabashi; Kazuo Hosokawa

The authors have investigated the sealing characteristics between the surface of an annular wedge-shaped plastic gasket and a smooth seal face of a rigid ball in static contact. The following results were obtained from gas leak tests, calculation of the deformation of a wedge-shaped gasket and a compression test. ( 1 ) In order to seal tightly, a contacting width of a wedge resulting from the plastic deformation of a gasket was required because of the work hardening of the surface irregularities on the gasket. ( 2 ) The contacting width of a wedge increased with a decrease in the conical half-angle of the seal face, θ. Therefore, the linear sealing load, Pc/l, decreased with a decrease in the θ-values. For example, the value of Pc/l at θ=15°was about 0.5 times that at θ=90°. ( 3 ) The recommended values of θ were in the range from 10°to 35°, and it was possible to forecast the Pc/l-values corresponding to that range.


Transactions of the Japan Society of Mechanical Engineers. C | 1992

Evaluation of Three-Dimensional Shape of Steel Ball by Spherical Harmonic Function.

Fumihiro Itoigawa; Takashi Nakamura; Koichi Funabashi

In the previous report, it was shown that harmonic analysis results on the three-dimensional shape of a steel ball obtained by use of spherical functions gave good evaluations of characteristics of steel balls used in a bearing assembly. However, this type of analysis is inadequate for evaluating the shape of the ball geometrically. In this paper, first, the possibility of three-dimensional geometrical evaluation by spherical harmonic analysis is described. The reference direction is defined as the index for directivity of each order of the spherical component and has no relationship with the coordinates for measurement. This reference direction or the value of each spherical component for which this direction is obtained, is utilized to illustrate and evaluate the spherical shape of the steel ball. Second, the method for estimating the three-dimensional shape of the steel ball by two-dimensional measurement is explained (e. g., a roundness meter). Mean Fourier coefficients of cross-sectional forms of the steel ball are theoretically calculated, and the correlation between this value and the harmonic analysis result obtained through the use of the spherical functions is obtained.


Journal of The Japan Society for Precision Engineering | 1993

Tool Offset Calculation by Crosscorrelation Function and Machining Test for Relief Map.

Takashi Nakamura; Koichi Funabashi; Hideo Fujimoto; Fumihito Yamazaki; Isao Hasegawa


Lubrication Science | 1991

Effects of directional properties of roughness and tangential force on pressure flow between contacting surfaces

Takashi Nakamura; Koichi Funabashi


Jsme International Journal Series C-mechanical Systems Machine Elements and Manufacturing | 1992

Harmonic Analysis by Spherical Function for Evaluating Form Error of Spherical Parts

Fumihiro Itoigawa; Takashi Nakamura; Koichi Funabashi


Transactions of the Japan Society of Mechanical Engineers. C | 1990

Spherical form error measurement with two-dimensional fourier transform.

Fumihiro Itoigawa; Koichi Funabashi; Takashi Nakamura


Transactions of the Japan Society of Mechanical Engineers. C | 2001

Fundamental Characteristics of a Wedge-Shaped Metal Seal.

Yoshio Matsuzaki; Isami Nitta; Kazuo Hosokawa; Koichi Funabashi


Transactions of the Japan Society of Mechanical Engineers. C | 1993

Steel Ball Lapping by Lap with V-shape Groove

Fumihiro Itoigawa; Takashi Nakamura; Koichi Funabashi

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Takashi Nakamura

Nagoya Institute of Technology

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Fumihiro Itoigawa

Nagoya Institute of Technology

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Kazuo Hosokawa

National Institute of Advanced Industrial Science and Technology

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