engleski

The role of feed speed and wood species in the chipped wood particle size distribution

Cilj je rada prikazati i usporediti granulometrijski sastav drvnih čestica nastalih tijekom piljenja hrastovih i bukovih uzoraka pri različitim posmičnim brzinama. Uzorci usitnjenog drva prikupljeni su tijekom piljenja hrastovine i bukovine sa sadržajem vode 8 – 12 % pri četiri posmične brzine (vp1 = 2 m/min, vp2 = 4 m/min, vp3 = 6, 5 m/min i vp4 = 13 m/min). Analiza dobivenih rezultata dala je vrlo vrijedne zaključke za određivanje najmanje veličine čestica koje nastaju s povećanjem posmične brzine. Pri svim istraživanim uvjetima mehaničke obrade drva piljenjem zabilježeno je veće usitnjavanje uzoraka hrastovine u odnosu na uzorke bukovine. Udio čestica granulacije od 0, 2 mm pa sve do 2 mm i većih, raste s povećanjem posmične brzine kod obje vrste drva, a udio čestica granulacije od 0, 09 mm do 0, 2 mm opada s povećanjem posmične brzine. Razlog tomu je odvajanje čestica okomito na smjer vlakanaca što je uzrokovano maksimalnom visinom lista pile iznad obratka. Na temelju dobivenih rezultata određeno je kod koje veličine čestica dolazi do suprotnog utjecaja posmične brzine na povećanje udjela sitnijih čestica štetnih za respiratorni sustav čovjeka.

circular saw; feed speed; granulometric composition of wood particles; the smallest size of wood particles

The aim is to show and compare the granulometric composition of wood particles created during sawing oak-wood and beech-wood samples at different feed speeds. The samples of chipped wood were collected during sawing oak-wood and beech-wood with a water content of 8 - 12% in the four feed speed (vf1 = 2 m/min, vf2 = 4 m/min, vf3 = 6.5 m/min and vf4 = 13 m/min). The analysis of the results gave valuable conclusions for determining the minimum size of particles produced by increasing feed speed. At all analyzed conditions of mechanical wood processing sawing, greater fragmentation patterns of oak-wood compared to the samples of beech-wood were recorded. The proportion of particles with a grit of 0.2 mm up to 2 mm and larger, increases by increasing feed speed in both wood sorts and the proportion of granulation particles with a grit from 0.09 mm to 0.2 mm decreases by increasing feed speed. The reason is the separation of particles perpendicular to the fiber direction which is caused by the maximum height of the saw blade above the sample. Based on the results, it is determined at which particle size the opposite influence of feed speed occurs to increase the proportion of smaller par