Cutting Power during Milling of Thermally Modified Pine Wood

The paper presents experimental testing results of cutting power of thermally modified wood of Scots pine (Pinus sylvestris L.) during lengthwise milling. The process of heat treatment was performed in the atmosphere of superheated steam, at temperatures of 130, 160, 190 and 220 °C, maintaining an identical heating time of 4 h for all modification variants. Cutting power was determined during milling of the radial surface of modifi ed and non--modified samples. It was calculated as the difference of power used by a milling machine during wood machining and at idling. Based on the results of measurements, it was found that, in the case of modified wood, cutting power decreases with an increase in modifi cation temperature (the dependence being linear) and increases with an increase in the working engagement. At temperatures exceeding 160 °C, the power required for milling of modified wood is lower than cutting power for non-modified wood. The experiment indicated a significant reduction of cutting power with an increase in wood modification temperature. It was also found that an increase in the working engagement results in an increase of cutting power both in thermally modifi ed and non-modified wood.U radu su prikazani rezultati eksperimentalnih istraživanja snage rezanja toplinski modificiranog drva običnog bora (Pinus sylvestris L.) tijekom njegove obrade glodanjem. Proces toplinske obrade borovine proveden je u atmosferi pregrijane pare, pri temperaturi od 130, 160, 190 i 220 °C, uz jednako vrijeme grijanja od četiri sata za sve varijante modifi kacije. Snaga rezanja određena je pri glodanju radijalne površine modificiranih i nemodificiranih uzoraka, a izračunana je kao razlika snage izmjerene tijekom rada stroja pri glodanju uzoraka i tijekom praznog hoda stroja. Na temelju rezultata mjerenja utvrđeno je da se snaga rezanja pri obradi modificiranog drva smanjuje s porastom temperature modifikacije (ovisnost je linearna), a povećava se s povećanjem visine dodatka za obradu (visine glodanja). Snaga potrebna za glodanje drva modificiranoga na temperaturama višim od 160 °C manja je od snage rezanja za obradu nemodificiranog drva. Eksperiment je pokazao znatno smanjenje snage rezanja s povećanjem temperature modifikacije drva. Također je utvrđeno da je povećanje visine dodatka za obradu rezultiralo povećanjem snage rezanja, kako pri obradi toplinski modificiranoga, tako i pri obradi nemodificiranog drva