Wear resistance of woodcutting knives, sharpened by planetary abrasive instrument

Abstract

The problem of thin milling knives sharpening that exists on woodcutting enterprises has been studied. The research shows that any of cooling methods used in practice during sharpening process is not preventing completely structural modifications on steel surface sheets caused by the immediate effect of temperature. If comform characteristics of abrasive wheel will not be adapted to grinding regimes and instrument materials, either the secondary hardening of the blade together with the creation of hard, but fragile structure, or considerable decrease of its solidity as a result of steel discharge may occur. Both are leading to the quick blunting of the instrument, in case of small sharpening angles, as a result of the demolishment of discharged or crumbled blade, repeatedly sharpened. One of the most effective solution for this problem is the decrease of thermal field during sharpening. This problem might be solved by the replacement of solid abrasive wheels by the wheels with ended surface. Analysis of experimental data, received at “Khvoya” enterprise, demonstrated that the endurance of the knives labeled 9ХФ, sharpened by planetary abrasive instrument, is much higher during the fining of various wood sorts than the endurance of the same knives sharpened by solid abrasive wheel. The results of experimental analysis confirmed the possibility of woodcutting knives sharpening, produced with steel 9ХФ, sharpened by the abrasive wheel with driven cups. Due to correctly selected sharpening modes, sharpening quality is high, and process efficiency increased by 1,8. The research demonstrated, that after 6000 m of cutting path, the radius of blade rounding of endured knife, sharpened by planetary abrasive instrument, decreases by 1,3 than the knife sharpened by solid abrasive instrument. It was identified that during the oak fining the intensiveness of knife’s processing is 2,3 times higher than during beech fining, in case the use of knives sharpened by planetary abrasive instrument and solid abrasive wheel. It was determined that after 148 000 m of cutting path of pine tree, the radius of blade rounding of knives, sharpened by solid abrasive wheel is ρ=24,1 μm, which is 1,34 times bigger than the radius of blade rounding of knives, sharpened by planetary abrasive instrument, that equals ρ=18 μm.