DIGITALNA ARHIVA ŠUMARSKOG LISTA
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|ŠUMARSKI LIST 1-2/1965 str. 40 <-- 40 --> PDF|
oštrenje. Zavisnost ugla oštrenja od prečnika turpije i nadvišenja »h« je jako
izražena, što se pri oštrenju bez upotrebe odgovarajućih naprava negativno odražava
na kvalitet oštrenja.
Ovim razmatranjima obuhvatili smo najvažnije faktore u vezi sa oštrenjem
zuba lanaca motornih pila koje se danas upotrebljavaju u eksploataciji šuma.
Iz izloženog dovoljno je jasno da je mišljenje o težini oštrenja zuba motornih
pila relativno i da se više odnosi na vreme i napor, a mnogo manje na složenost
oštrenja i potrebnu preciznost.
1. Anikin , B. P.: Mehanizacija lesorazrabotok, 1940.
2. Popović , V.: Iskorišćavanje šuma, 1954.
3. Beršadskij , A. L.: Rezanie drevesini, Moskva, 1956.
THE CUTTER AND THE ELEMENTS OF SHARPENING POWER-SAW CHAINS
The author deals with the elements and the significance of the cutter and with
the sharpening of power-saw chains used in logging. He points out the superiority
of the new tooth form (Fig. 2) over the old tooth form of non-mechanized saws (Fig. 1).
In the introduction he explains the role of individual elements of the cutter in the
light of the theory of the wood-cutting process. On a tooth edge the author distinguishes
three parts: horizontal (Ho), vertical, transition (Po). On explaining the role
of the individual parts of the cutter or the edge, he points to the rough notion of the
elements of sharpening in practice, and after some critical comments gives the definitions
of the sharpening angles for the individtial parts of the cutter.
The major part of the paper is engaged with the question of the dependence of
the sharpening angle of the individual part on the file diameter and other factorj.
The author stresses that sharpening angle of the vertical part of cutter depends on
the angle which takes the file axis towards the direction of the chain motion, but ho
likewise points to the fact that the sharpening angle of the horizontal part of the
cutter does not depend on the file angle mentioned towards the direction of the chain
motion. He illustrates this in Figs. 5, 6, and 8, presenting also a matematical expression
for these relations. Equation 1 represents the dependence of the sharpen´n^
angle of the horizontal cutter part (minimum angle) on the file diameter and the tile
superelevation above the cutter edge. Equation 2 indicates the dependence of the
sharpening angle of the horizontal cutter part on the so-called relative file superelevation
above the cutter edge only, while the diagrammatic representation of this
dependence is given in Fig. 8.
According to the author, the sharpening angle of the horizontal part does not
depend at all on the angle which the files towards the direction of the chain motion,
but only on the file superelevation above the cutter edge. In this connexion the author
introduces the concept of the so-called minimal or tangent angle of sharpening from
which he distinguishes the over-all angle of sharpening — the concavity of the cutter
front-side. When the file superelevation above the cutter edge remains the same in
the relative amount (in parts of file diameter), then also the initial sharpening angle
remains the same (Fig. 5b).
On the basis of an analysis of the elements and role of the indicidual parts of
the cutter edge, the author draws the conclusion about the superiority of the new
cutter over the teeth of non-mehanized saws, and in doing so he especially points
to a smaller cutting angle and the sharpening angle of the horizontal cutter part.
Then he stresses the significance of precision sharpening, and the drawbacks when
the sharpening operation is performed without adequate devices. He also points to the
imperfections of sharpening with cylindrical files.