Abstract
The article presents a new thermo-mechanical machining method for the manufacture of long low-rigidity shafts which combines straightening and heat treatment operations. A fixture for thermo-mechanical treatment of long low-rigidity shafts was designed and used in tests which involved axial straightening of shafts combined with a quenching operation (performed to increase the corrosion resistance of the steel used as stock material). The study showed that an analysis of the initial deflections of semi-finished shafts of different dimensions and determination of the maximum corrective deflection in the device could be used as a basis for performing axial straightening of shaft workpieces with simultaneous heat treatment and correction of the initial deflection of the workpiece. The deflection is corrected by stretching the fibers of the stock material, at any cross-section of the shaft, up to the yield point and generating residual stresses symmetrical to the axis of the workpiece. These processes allow to increase the accuracy and stability of the geometric shape of the shaft.
Highlights
Long low-rigidity shafts are manufactured from bar stock with substantial curvature
Differences in the response of the components of the technological system to machining, considerable effect of technological heredity on operational reliability, warping of semi-finished products caused by uneven residual stresses generated at all stages of machining, and low thermal stability of parts make the process complex and not easy to control (Zhao et al 2020; Ye et al 2020)
Research on methods of increasing the efficiency and quality of finished products manufactured in a traditional way, as well as the results of studies on their industrial application show that machining processes can be intensified by: selecting technological parameters and process conditions that allow to obtain the required accuracy of shafts (Zhang et al 2019; Świć et al 2017; Taranenko et al 2010); developing alloys with a high dimensional stability, relatively low and stable thermal expansion coefficients (Tong et al 2018), and a high elastic modulus (Vrancken et al 2012); and using appropriate stabilizing treatment operations (Jianliang and Rongdi 2006; Urbicain et al 2012)
Summary
Long low-rigidity shafts are manufactured from bar stock with substantial curvature. They are commonly used in the aerospace industry, precision mechanics, the automotive industry, and as special tools. Research on methods of increasing the efficiency and quality of finished products manufactured in a traditional way, as well as the results of studies on their industrial application show that machining processes can be intensified by: selecting technological parameters and process conditions that allow to obtain the required accuracy of shafts (Zhang et al 2019; Świć et al 2017; Taranenko et al 2010); developing alloys with a high dimensional stability, relatively low and stable thermal expansion coefficients (Tong et al 2018), and a high elastic modulus (Vrancken et al 2012); and using appropriate stabilizing treatment operations (Jianliang and Rongdi 2006; Urbicain et al 2012).
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