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| 1.
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田中, 隆太郎 ; 上田, 隆司 ; 細川, 晃 ; 林, 勇伝 ; 山田, 啓司
概要:
This study deals with the machinability of steels after heat treatment with CO2, laser using h-BN powder and blast furna
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ce slug as absorbent. h-BN is well known as solid lubricant. As for blast furnace slug, its composition is similar to that of inclusions in calcium dioxide steel that shows good machinability. The absorbance of slug and h-BN were more than 80%, so it is said that these powders can be used as absorbent for CO2, laser. Only in the case of h-BN, absorbent was melted into substrate and its depth was about 200 μm. When turning the steels after laser heat treatment using h-BN power and blast furnace slug as absorbent, carbide tool showed smaller tool wear than the case of carbon type absorbent. In the profile of the machined surface, there was a wave of about 5 μm in amplitude and its wavelength was equal to the feed rate of laser in heat treatment. This is because the workpiece surface after laser heat treatment has a periodic distribution in hardness. The hardness in the surface layer of workpiece was higher than that of the substrate.
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| 2.
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山田, 啓司 ; 小谷, 祐司 ; 上田, 隆司
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The temperature of workpiece irradiated with CO2 laser is measured using a new type of infrared radiation pyrometer with an optical fiber. In the pyrometer, a chalcogenide optical fiber and a two-color detector which consists of InSb and
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InAs detector are used. The power intensity of the laser beam during the exposure time and the two dimensional picture of the intensity distribution of the laser beam are measured experimentally. The measuring system for the intensity distribution of laser beam consists of MCT cell and an optical fiber. The temperature distribution on the workpiece irradiated with laser is calculated numerically using FEM for unsteady state. The change of physical properties of materials is considered. Comparing the experimental results with the calculated ones, the absorptivity of the work material for CO2 laser is obtained.
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| 3.
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森田, 精一 ; 山田, 啓司 ; 細川, 晃 ; Al, Huda Mahfudz ; 上田, 隆司
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上田, 隆司 ; 山田, 啓司 ; 及川, 志郎 ; 細川, 晃
概要:
Laser forming is the thermal process to deform a metal plate using the thermal stress produced by the rapid heating with the laser. In this study, the influence of irradiating conditions of CO2 laser on the bending angle of the
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workpiece is investigated. The temperature at the back surface of the workpiece irradiated with CO2 laser is measured using a two-color pyrometer with an optical fiber. The temperature distribution in the workpiece is calculated using the FEM thermal analysis. Simple bending experiments with one-way laser scanning are carried out. Stainless steel SUS304 of various thickness is used as work material. The results obtained are as follows. The bending angle is proportional to the temperature of the workpiece irradiated. The temperature of workpiece increases with the increase of laser power, the decrease of feed rate of the laser beam and the decrease of plate thickness. After all, the bending angle becomes larger with the increase of laser power, the decrease of the feed rate and the decrease of the thickness of the plate. The temperature of the workpiece can be used as a signal to control the deformation of the workpiece.
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上田, 隆司 ; 山田, 啓司 ; 篠崎, 道 ; 細川, 晃
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Perforatability and thermal damages of dental hard tissues with two kinds of YAG laser are investigated for the purpose of making the cavity and forming the abutment tooth. The perforatability of dentin with laser beam depends on the
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absorptivity for laser beam, the laser power, the pulse duration and the number of laser pulses. Approximately 65% of Er:YAG laser beam is absorbed at irradiated surface of dentin, but the absorptivity for Nd:YAG laser beam is only 17%. High perforatability is accomplished using Er:YAG laser because of its higher absorptivity. There is a linear relation between the perforated depth and the number of pulses. Higher laser power and larger pulse duration improve the perforatability, in the same time, induce thermal damages on dental hard tissue such as thermal cracks and burning of dentin. Lower laser power and smaller pulse duration makes it possible to make fine cavities without thermal cracks and burning in even with Nd:YAG laser.
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| 6.
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加藤, 寛満 ; ヘリー, モフタディ ; 山田, 啓司 ; 上田, 隆司 ; 細川, 晃 ; 田中, 隆太郎
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千徳, 英介 ; 上田, 隆司 ; 山田, 啓司 ; 細川, 晃 ; 田中, 隆太郎 ; Sentoku, Eisuke ; Ueda, Takashi ; Yamada, Keiji ; Hosokawa, Akira ; Tanaka, Ryutaro
概要:
金沢大学理工研究域機械工学系<br />A thin stainless steel is bended by the irradiation of CO2 laser. Then both temperatures at irradiat
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ed and opposite surfaces are measured using two sets of the two-color pyrometer with an optical fiber. In this study, we investigate the effect of temperature difference between irradiated and opposite surfaces on deformation mechanism. The increase of diameter of laser beam and the decrease of thickness of material make the temperature difference smaller and change deformation mechanism from Temperature Gradient Mechanism (TGM) to Buckling Mechanism (BM).CO2レーザを用いてステンレス板材のフォーミング加工を行い,同時にレーザ照射部表面および裏面温度を2組の光ファイバ型2色温度計を用いて測定し, 表裏温度差と変形メカニズムの関係を調べた.実験結果から板厚が小さくなるほど,ビーム径が大きくなるほど表裏温度差は小さくなり,変形メカニズムが温度勾配メカニズム(TGM)からバックリングメカニズム(BM)へと変化することがわかった.<br />出版者照会後に全文公開
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| 8.
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千徳, 英介 ; 上田, 隆司 ; 山田, 啓司 ; 細川, 晃
概要:
Laser forming of a sheet metal is the bending process caused by the thermal stresses which is produced in the sheet by l
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aser irradiation. Therefore, the temperature distribution in the sheet irradiated with laser beam is one of important factors to determine the bending angle of the sheet. In this study, the influence of temperature distribution and the experimental conditions like the diameter of laser beam and the thickness of a sheet on the bending angle is investigated experimentally. The temperatures of a surface irradiated with CO2 laser and its opposite surface are measured using an infrared radiation pyrometer with an optical fiber. As a result, the bending angle is directly proportional to the temperature Ts at the sheet surface irradiated with laser beam and the beam diameter D, and inversely proportional to the thickness h of the sheet. A parameter indicated by D1.41Ts1.5/h1.7 has high correlation with the all bending angles obtained under various experimental conditions. 様々な加工条件で板材のフォーミング加工を行い, 同時にレーザ照射部表面および裏面温度を測定し, 加工条件と照射温度の変形角への影響を調べた. その結果, 変形角はレーザビーム径の1.4乗に比例し, 照射温度の1.5乗に比例し, 加工物の板厚の1.7乗に反比例しており, これらの結果より導出した式は定性的に加工条件の変形角への影響を良く表している.
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| 9.
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藤江, 典久 ; 三野, 大樹 ; 上田, 隆司 ; 細川, 晃 ; 山田, 啓司 ; Fujie, Norihisa ; Mino, Daiki ; Ueda, Takashi ; Hosokawa, Akira ; Yamada, Keiji
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金沢大学理工研究域機械工学系<br />Thermal stress cleaving is a prospective technique for separating a wafer or thin plate from brittle
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materials such as glasses and ceramics. In this paper, the cleaving mechanism of a glass and a sapphire irradiated with CO2 laser is investigated. A high frequency pulsed laser is used for the purpose of investigating the mechanism of crack propagation more precisely. The AE signal is measured to examine the characteristics of crack propagation. Thermal damage to the surface of the glass causes the deterioration of cleaving accuracy. Consequently, it is important to minimize the thermal damage by controlling the prosess parameters.<br />熱応力割断はガラスやセラミックといった脆性材料の加工方法として，近年注目されてきている．本研究では，CO2レーザを用いた液晶表示用ガラスおよびサファイアの割断メカニズムについて調査している．き裂の進展メカニズムをより精密に調べる為，高周波数パルス発振のレーザ加工機を用いている．またAE信号測定を行い，き裂進展の状況を観測している．その結果，AE信号によって，き裂の挙動を観察することができることを示している．ガラス表面の熱損傷によって，割断の精度が悪化する為，加工パラメータを制御し，熱損傷を抑えることが重要である．<br />出版者照会後に全文公開
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| 10.
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Al Huda, Mahfudz ; 山田, 啓司 ; 上田, 隆司
概要:
The temperature of the flank side of the cutting tool edge that has large affect on machined surface integrity is measur
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ed using two-color pyrometer with a fused fiber coupler. The infrared rays radiated from the cutting tool edge are accepted by an optical fiber, and separated to two optical fibers at the fused fiber coupler. Each fiber leads the infrared ray, respectively, to two infrared detectors with different characteristic of spectral sensitivity. Temperature is obtained by calculating the ratio of the output voltage from these two detectors. A CBN tool (CBN content : 60 volume percent, density : 3000 kg/mm2) is used as the cutting tool. Annealed steel (S45C), bearing steel (SUJ2), and quenched steel (S55C) are used as the cutting materials to investigate their affect on the tool edge temperature. The results obtained are as follows : (1) The technique developed is suitable for measuring the temperature of the flank side of the cutting tool edge. (2) The temperature of the cutting tool edge is highly effected by cutting speed. (3) The temperature increases slightly with the increase of depth of cut and feed rate. (4) On the cutting of quenched steel which has the largest hardness among these three materials, the temperature is about 50°C higher than that on the bearing steel cutting, and the temperature of the annealed steel cutting is the lowest.
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