Features of the main technological and design parameters of the stationary stand of the KhPTR mill for rolling precision heat-exchange tubes
Kravchenko O. V. Features of the main technological and design parameters of the stationary stand of the KhPTR mill for rolling precision heat-exchange tubes // Herald of the DSEA. – 2019. – № 2 (46).– P. 64–67.
Nowadays, the KPTR type mills of the design of the former VNIIMETMASH are widely spread. The advantages of these mills are the small size and simplicity of the working tool, which determines the overall relatively small weight of the cage and its large technological capabilities in the production of pipes. At the pipe factories of the former USSR, these mills are the main ones in the production of precision heat-exchange tubes, including those for fuel rod housings made of zirconium, nickel and titanium alloys, tubes for heat-absorbing assemblies, etc. Studies show that the performance of KhPTR camps is not limited by force parameters and metal ductility, but is mainly hampered by allowable reductions in the instantaneous deformation zone from the point of view of ensuring the required surface quality and the accuracy of the geometric dimensions of the pipes and the capabilities of the rotary mechanism with the Maltese cross. The relatively low productivity of the operating CPP mills is largely due to the small length of the crimping zone, which is associated with the kinematics of the cage, according to which the separator stroke amounts to about 60% of the stroke length of the stand cage driven by a crank mechanism. The purpose of the article is to determine the main features of the stationary stand design of the KPTR mill for rolling precision heat exchanging tubes, in which the course of the separator with working rollers would be equal to the course of the yoke. Using the stationary stand of the CPR mill allows, without a significant change in the mill design, not only increase the accuracy and quality of the pipe surface, but also multiply the mill performance by maximally leveling the elastic deformation of the “working roller - stand body” system when using a fixed thick-walled cage as the stand body, increasing the separator stroke by 1.7 times, as well as reducing the weight of the moving parts of the stand by more than 2 times.
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