Determination of the Stress Concentration Factor in the Tooth Spaceof a Band Saw under Tension

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UDС

621.935

DOI:

10.17238/issn0536-1036.2016.3.117

Abstract

The failure of the saws due to the fatigue effect is the most common cause of the ineffective time of the band saws. The formation of cracks in the tooth space not only reduces the band saws performance, but also increases the cost of the acquisition and preparation of the saws and creates a danger for the workers. The tooth space parameters, which are the stress con-centrators, have a great influence on the fatigue strength of the band saws. To assess the strength of a band saw we should know the stress concentration factor in the tooth space of a band saw on its bend on the wheels and tension. Knowledge of these factors let us to deter-mine the equivalent stress concentration factor and to calculate the safety factor of a band saw. Previously, the authors identified the theoretical and actual stress concentration factors in the tooth space of a band saw under bending and the sensitivity coefficient of materials of a band saw. The paper presents the experiments to determine the theoretical stress concen-tration factor of a saw under tension. A band saw sample was fixed up in the universal test-ing machine head TIME WDW 200E. The tension of a band saw sample was performed by the vertical displacement of the upper head. 5 resistive strain gages were fixed in the middle of the free length of the sample: one was near the tooth space; others were distributed at the equal distances along the blade width of the sample. The stresses were characterized by a voltage value in millivolts measured by the voltmeter. The theoretical stress concentration factor of a band saw under tension equal to 1.62 is obtained. The actual stress concentration factor in the tooth space of a band saw under tension is 1.53 at the sensitivity coefficient of materials (steel 9ХФ – alloy structure steel) of a band saw, equal to 0.85.

Authors

G.F. Prokof'ev, Doctor of Engineering Sciences, Professor O.L. Kovalenko, Postgraduate Student

Affiliation

Northern (Arctic) Federal University named after M.V. Lomonosov, Naberezhnaya Severnoy Dviny, 17, Arkhangelsk, 163002, Russian Federation;
e-mail: g.prokofjev@narfu.ru, o.kovalenko@narfu.ru

Keywords

band saw, fatigue crack, stress concentration factor in the tooth space, sensitivity coefficient of materials of a band saw, safety factor of a band saw.

References

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Received on September 18, 2015