刀角對CNC花鉋機端面銑削特性之影響

CNC花鉋機之木製品生產過程中，端面銑削無可避免，由於CNC花鉋機使用之刀徑較小，不易獲致良好加工面，另一方面，端面之砂磨又極為不易。因此，植研究側以12000 rpm之主軸轉數、2400 mm/min之送材速度及2 mm之切削量銑杉木及硬槭端面，以探討刀角對端面銑削品質之影響，並分析面缺點產生機制。試驗結果顯示，下向端面銑削所產生之chip III量相當高，杉木介於44.3%~63.1%（重量分佈）之間，硬槭則介於25%~57.7%；而端面銑削所產生之缺點，大致可分為Split-I、Split-II、Split-I II三種劈裂形態及Burr-I、Burr-II及Burr-N三種起毛形態。上向端面銑削中，杉木會產生Split-II及Split-I II種嚴重之劈裂現象，而硬槭則產生Split-I；下周端面銑緅則依刀角之不同，產生不同程度之起毛缺點，由於劈裂為一無法彌補之缺，故木材端面銑削宜採下向銑削方式。本試驗亦顯示刀角對端面加工面銑削品質有極大之影響，杉木端面銑緅顯示刀端角40°隨斜度角增加，加工面品質惡化，刀端角50°及60°則隨斜度角增加，加工面品質獲得改善，硬槭則無明顯趨勢。此外，大部分刀角之斜度角改變對切削音壓改變值皆在3dB或5dB以下，人耳無法聽出其差異性。

關鍵字

端面銑削；刀角；劈裂；起毛；加工面粗糙度；切削音壓

並列摘要

End-grain milling by CNC router could not be avoided during the wood machining. Because of the small diameter of straight router-bit, a good machining surface is always hard to obtain. Moreover, it is difficult to sand the machining surface of end-grain milling. Effects of the rake angle and sharpness angle of straight router-bit with diameter 12mm on cutting performance and defect mechanism were explored in this study under 12000 rpm of spindle speed, 2400 mm/m in of feed speeds and 12 mm of cutting depth in end-grain up- and down-milling of China-fir and hard maple by CNC router. Experimental results indicated that large quantities of chip III were produced in end-grain down-milling of China-fir and hard maple. The relative proportions of chip III in weight basis was from 44.3% to 63.1% and from 25% to 57.7% for China-fir and hard maple, respectively. The defect could be recognized as split and burr types. Split defects occurred in up-milling including Split- I ' Split- IT and Split- I IT. Burr defects observed in down-milling containing Burr- I 'Burr- IT and Burr-N. SplitIT and Split- I IT were always found during end-grain up-milling of China-fir, but hard maple produced only Split- I defect. The degree of burr depended on tool angle for end-grain down-milling. Because split was a serious defect for wood machining, down-milling was the better choice for end-grain milling. Results also showed that tool angle significantly affected the cutting pe rfo rmance during end-grain milling . The surface roughness(Rz) became worse as rake angle increased during milling of China-fir for sharpness angle of 40° . However, surface roughness (Rz) decreased as rake angle was increased for sharpness angle of 50° and 60°. But the quality of the machining surface for hard maple was not affected by rake angle. Furthermore, the difference of sound pressure level(dB) during milling of CHina-fir and hard maple among various rake angles were less than 3dB or 5dB which were not detectable by human ears.

並列關鍵字

End-grain milling ； Tool angle ； Split ； Burr ； Surface roughness ； Sound pressure level

國際替代計量

刀角對CNC花鉋機端面銑削特性之影響

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