旋削加工におけるmqlの効果:ファイバ遙統型2色温度計を用いた工具刃先温度の測定

摘要

旋削加工におぃては，工具寿命の延長，仕上げ面粗さの改rn善，加工精度の向上などを目的として切削液が広く使用されてrnぃる．しかしながら，近年，地球環境への配慮や切削液の処理，rnコスト低減などの理由から，切削液を使用しなぃ乾式切削や極rn微量の切削液を用ぃるセミドライ加工への移行が進められてぃrnる1）2）．このうち，乾式切削は切削温度が極めて高くなるためrnその適用には自ずと限界があり，研究の主眼は耐熱性工具の開rn発に置かれてぃる．そのため，極微量の切削油をミスト状にしrnて切削点に供給するMQL（Minimum Quantity Lubrication）切削rnが注目され，高能率化への期待が高まってぃる3）4）．%In this paper, the MQL turning of two types of ferrous metals: chromium-molybdenum steel SCM440H and pearlite malleable cast iron FCMP: is dealt with. The appropriate generating system of oil mist is constructed and the specified turning tool with oil hole is used. In order to verify the cooling effect of MQL, the tool temperature at the flank face is measured using a newly assembled fiber-coupled two-color pyrometer. In this new technique, a sensing fiber is inserted into a small hole that extends to the outer surface of the tubelike workpiece and it rotates with the workpiece. The thermal radiation accepted by a sensing fiber is noncontactly transmitted to the other fixed fiber and led to the two-color detectors. As for cutting force in turning of SCM440H, MQL is more effective in low cutting speed below 100 m/min. The tool temperature in MQL turning is approximately 100℃ lower than that in dry turning over the wide range of 30～300 m/min. In the case of FCMP, the tool temperature in dry turning at a cutting speed of 600 m/min reaches as much as about 1040℃, but it drops 920℃ in MQL turning.