Analysis of influence of tool wear on a quality of new made surface in drilling of wood panels

Pri obdelavi ivernih plošč je značilna zelo nizka življenjska doba orodja. Zagotavljanje visoke kakovosti robu na izstopni strani orodij pri vrtanju skoznjih izvrtin v obložene plošče je zelo težavno. V primeru, da so obremenitve pri vrtanju luknje skozi kompozit večje od sile iztrganja površinskega sloja, pride na izstopni strani do delaminizacije kompozita. Obremenitve pri vrtanju so odvisne od tehnoloških parametrov obdelave in sicer: podajalne hitrosti, hitrosti vrtenja orodja, kota konice orodja ter lastnosti obdelovanca. Z obrabo orodja naraščata sila v smeri vrtanja ter moment okoli osi vrtanja. Pri večjih obremenitvah pričakujemo slabšo kakovost novonastalih površin izvrtinpredpostavljamo, da je z meritvijo obremenitve orodja mogoče pred videti kakovost novonastale površine. Na obloženi iverni plošči smo z vrtalnima orodjema izvrtali 3842 oz. 5365 lukenj in z piezodinamometrom izmerili pritisno silo ter določili faktor delaminizacije. Ugotovili smo, da je optimalna velikost delaminizacijskega koeficienta 1, kar znaša pri pritisni sili 60 Ntu še ne pride do delaminizacije površine, nad temi vrednostmi pa so že vidne manjše poškodbe površine. Ocenjujemo, da je vrtanje še smiselno in kakovost površine še sprejemljiva do pritisne sile približno 82N ter delaminizacijskega koeficienta 1,08.It is typical in processing of particleboards that the tool wear is very high. Drilling through holes in a particleboard presents big problems in providing high quality edge on the exit side of the holes. In case that loads caused by drilling holes through particleboards are higher than delamination value of the surface layer the result is delamination on the exit side of the particleboard. Loads by drilling depend on cutting parameters : spindle speed, feed rate, tool point angle and workpiece characteristics. Tool wear increases the force in the direction of drilling, and the torque around axis of drilling. Higher loads caused by drilling holes lower the quality of surfaces. We can assume that measuring the tool loads the quality of such surfaces can be predicted. We have drilled 3842 and 5365 holes on coated particleboards with 2 clockwise drilling tools, and measured thrust force with piezo dynamometer . We also determined delamination factor. The optimal delamination factor with no surface delamination is 1, coming to approximately 60N of thrust force. Crossing that line causes minor damage on surface. The drilling is sensible till thrust force reaches approximately 82N , and delamination factor 1 . 08