Eiichi Sentoku

The Educational Effects on Sound Experiment of Duct Model: -Observation and Listening Experience in Demonstration-@@@-デモによる観る聴く体験-

2.管内の共鳴実験 送風用ダクトや配水管などの内部で共鳴が起こると大 きな音が発生し,苦情やトラブルの原因となる.この際, 管内部の音圧がどの ように分布している かを知ることは騒音 対策を講ずる上で非 常に重要である. そこで,デモンス トレーションで望ま れること(表1)を 考慮して,管内部の 音圧分布を可視化することを考えた.すなわち,ガラス管 の端部で音を発し,管の長手方向に共鳴する時には内部 の発泡スチロール球が音波でどのように動くかを観察で きるようにした.これはクントの実験としてよく知られて いる. 2.1 実験装置と共鳴モードの可視化 長さ1500mm,内径44mmのガラス管内部に直径約 5mmの発泡スチロール球をひと握り均等にばらまい た.管の一端はふさぎ,他端には55mm径のスピーカ (TOYO製70FB02BC)を取り付け,デジタル発信器 (KENWOOD製FG-273)で定めた周波数の正弦波信号 を増幅して音を発生できるようにした. スピーカからの出力は一定のままで周波数を少しずつ 動かすと,内部の発泡スチロール球が激しく踊り始め, ある周波数に近づくと球体はほぼ等間隔の何か所かに分 かれて集まりだした(図1). 発泡スチロール球がきれいに分かれた共鳴周波数で音

On the Cutting Performance of TiC-Cr3C2 Compound Ceramics Tool (Part 2)

In recent years. many ceramics and cermet tools with various kinds of properties have appeared on the market. The purpose of this paper is to clarify the tool life of TiC-Cr3C2 compound ceramics and TiC-Al2O3 ceramics tool on the machining of alloy steel at high cutting speed. The tool life was studied and discussed upon both continuous and Intermittent cutting by turning. The cutting speed for examination was 200 m/min, 250 m/min and 300 m/min. The results obtained are as follows; (1) In continuous cutting, tool life of TiC-Cr3C2 compound and TiC-Al2O3 ceramics tool was larger than those of cermet and ceramics tools. (2) The wear mechanism of TiC-Cr3C2 compound ceramics tool was pile up micro chipping on the tool edge. (3) In intermittent cutting, TiC-Al2O3 ceramics tool was appeared the longest tool life. (4) Since TiC-Cr3C2 compound ceramic and TiC-Al2O3 ceramics tool shows good cutting performance to the alloy steel, it is considered the cermet tool will be replaced by these tools.

On the Cutting Performance of TiC-Cr3C2 Compound Ceramic Tool

In recent years, many ceramic and cermet tools with various kinds of properties have appeared on the market. The purpose of this paper is to clarify the tool life of TiC-Cr3C2 compound ceramic tool on the prototype for the machining of carbon steel at high cutting speed. The tool life was studied and discussed upon both continuous and intermittent cutting by turning. The cutting speed for examination was 250m/min and 300m/min.The results obtained are as follows;(1) In continuous cutting, tool life of TiC-Cr3C2 compound ceramic tool was larger than those of cermet and ceramic tools.(2) In intermittent cutting, the chamfer angle of 30°on the edge gives the longest tool life. In this case, the failure on the tool edge was caused by pile up of micro chipping.(3) Since TiC-Cr3C2 compound ceramic tool shows good cutting performance to the carbon steel, the cermet tool will be replaced by this tool.

On the Wear Mechanism Study of Coated Cemented Carbides Tool by CVD

The purpose of this paper is to clarify the wear mechanism which occurs at high cutting speed. The alloys tool of coated cemented carbides with Al2O3+TiC by CVD was studied and discussed from the point of view of the relationship between flank wear and the condition of the occurrence of deposited metals on the tool surface, obtained by cutting tests and dynamic diffusion tests. In cutting tests by turning, the cutting speed was varied from 150 m/min to 400 m/min. The contact planes of both rectangular samples in a dynamic diffusion tests, inclined in 10 degrees to the horizontal plane, were kept at high temperatures ranging from 973 K to 1473 K for 30 minutes in an argon-gas environment. The main results obtained are as follows :(1) The best machining conditions of this tool were in cutting speed from 200 m/min to 250 m/min, and feed from 0.25 mm/rev to 0.35 mm/rev. (2) At high cutting speed, much deposited metal was observed on the tool edge, and this metal decreased the machined surface accuracy. (3) In the dynamic diffusion tests, the deposition between the coated layer and the work piece occurred at temperature of 1073 K or more. The coated layer was chipped from the matrix of cemented carbides at high temperature of 1373 K or more.

Machining performance for machinable ceramics. (Part 5). Drilling.

In recent years, many glass ceramics with various kinds of properties have appeared on the market. These ceramics are used for a few mechanical and electronic parts. Glass ceramics consisting of fiuor-phlogopite can be machined with tight tolerance using conventional metalworking equipment and tools. The purpose of this paper is to study the shape of drill edge and to find the mechanism of chipping on drill key hole in cutting with high efficiency. The chipping size was discussed upon both examination in drilling and analysis with the finite element method. The tests of drilling mica-ceramics were performed with twist drill of high speed steel by milling.The main results obtained are as follow: (1) Cutting of high speed and feed had an important effect on chipping size of drill key hole. (2) The tip angle of 90°on drill resulted in small chipping size. (3) The worn tool increased chipping on machining surface. (4) A large thrust in drillingincreased chipping of exit side on hole.

A Study on the Crater Wear Mechanism of Cermet Tools

The purpose of this paper is to clarify the wear mechanism at high cutting speed where mutual diffusion at interface comes to active.The relation between the crater wear rate and the condition of diffusion layer by cutting test and dynamic diffusion test, for reference, was investigated and discussed. Combination of materials was cermet tool of TiC type to plain carbon steel of 0.45%C. In the cutting test by turning, cutting speed was varied from 2.5 m/s to 7.5 m/s. In the dynamic diffusion test, the contact planes of both samples inclined at 5 degrees under axial load, were kept at high temperature ranging from 1273 K to 1473 K for 30 minutes in argon gas environment. The surface of samples was observed and analyzed using SEM and EPMA. The main results obtained are as follows:(1) At a tool face temperature over 1300 K, the wear rate depends strongly upon the temperature.(2) In this circumstance, a Ti-rich layer on the worn surface of tool is observed, which is hard and a brittle layer of several um thick.(3) A model can be proposed in which the wear proceeds by the repetition of formation and tearing off of the layer.(4) The layer is produced as a result of diffusion at interface and squeeze of binding material of Ni by pressure.