Creation of fields of normalized residual stresses in the blade of a frame saw by thermal influence

The efficiency of a saw frame is determined by the performance and operational reliability of the tool – a frame saw. During operation, a frame saw is exposed to complex effects of force and temperature factors, which must be taken into account when preparing the saw for operation. The ability of a saw to counteract the components of the cutting force is characterized by its rigidity and stability. To obtain a straight cut, it is necessary to ensure the standardized stability, the working rigidity of the blade. This is achieved by longitudinal tension of the saw. In practice, the tension stresses of the edges of the blade are increased by weakening its middle part. For this, the saw blade is subjected to rolling. It should be noted that rolling does not ensure the formation of a uniform stress field over the cross section of the blade, and is accompanied by a fracture of the metal along the rolling trace, which reduces the mechanical strength of the saw. The article discusses a new approach – to form residual stress fields in the saw blade by thermal action. The considered technology of preparing a frame saw for operation is based on the thermal method of creating stresses in the saw blade by pulsed induction heating of local longitudinally located strip sections without kinks along the entire crosssection. When heating, secondary thermoplastic residual deformations occur in the array of the strip section, which ensure the formation of residual thermoplastic stresses in the boundary zone of adjacent sections of the saw blade. This ensures the formation of normalized residual stress fields in the saw blade and an autonomous effect of compression of the middle part and tension of the rear and front edges of the saw blade appears, allowing to ensure a stable state of the frame saw in the cut with a normalized tension force of the frame saw blade between the grips. The paper provides a quantitative assessment of residual thermoplastic stresses. A new approach to the formation of normalized residual stresses in a frame saw blade by short-term concentrated thermal action on strip sections of the blade allows the formation of fields of residual thermoplastic stresses, increasing the transverse rigidity of the blade and the stability of the saw in the cut.

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