Test of Bulging Stress Concentration Factors in the Band Saw Notches

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Abstract

The article gives the description of the tests of bulging stress concentration factors in the band saw notches. Animation and static tests were carried out at the pilot plant. As a result the sensibility factor of the saw material is identified. After the tests defining the concentration saw tensile stress factors the equivalent stress concentration coefficient for band saw stress calculation can be determined. The endurance limit of the material patterns of the band saws with the sawteeth and without the sawteeth at the zero-to-tension stress cycle is also defined. It will allow constructing a limiting amplitude scheme. Thus, it will be possible to define the limit stress values for any asymmetric depth cycles of band saws. Abroad the wood-milling band saws are made from hard-rolled tampered steel, as well as domestic saws of steel 9ХФ. The tapping specification of foreign saws is similar to domestic saws, though they are alloyed by additional elements to improve their operational properties. High-impact alloyed steels are also highly sensitive to the stress concentration. Therefore, the conclusions made in the article are also valid in relation to the foreign band saws. According to the results of the experimental studies we have drawn the following conclusions:

1. The results of performed tests confirm that the destruction of band saws is of fatigue nature.
2. The theoretical and actual coefficients of stress concentration at symmetric bending in the notches of the band saws 3405-0032 GOST 6532-77 steel 9ХФ are respectively: α_κ = 1.27, κ_эф = 1,23. The sensibility factor of the band saws material for the same conditions is also determined: q = 0.85.
3. To increase the band saws life the following meaningful and technological measures are necessary:
   – to edit a notch profile;
   – to slow the process of the fatigue cracks development, for example, by the thermo-softening method [10].
4. After the research of the stress concentration factors of the tensile saw the equivalent stress concentration coefficient should be defined. This coefficient can be used at the band saws stress calculation.

Authors

• G.F. Prokof'ev, Doctor of Engineering, Professor
• O.L. Kovalenko, Postgraduate Student
• S.A. Cherepanov, Postgraduate Student
  
  Northern (Arctic) Federal University named after M.V. Lomonosov,
  Naberezhnaya Severnoy Dviny, 17, Arkhangelsk, 163002, Russia;
  е-mail: g.prokofjev@narfu.ru,
  е-mail: o.kovalenko@narfu.ru

Affiliation

Keywords

References

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