Affiliation:
1. Ural Federal University after the first President of Russia B. N. Yeltsin
Abstract
The article discusses an example of an analytical approach to predicting one of the important indicators of pipe quality ‒ the accuracy of wall thickness. Modeling of changes in eccentric wall thickness variation during radial compression of a pipe in a round gauge on a round mandrel was carried out using the variational method by minimizing the functionality of the virtual speed principle. The procedure for solving the problem on a computer included the formation of a geometric model of the initial wall thickness variation, construction of a field of virtual flow velocities accurate to two variable parameters, and minimization of the functional by numerical methods. As a model of the initial wall thickness variation, eccentric model was chosen, the share of which is 60‒80 % and occurs at the firmware stage. The virtual velocity field in the spherical coordinate system is chosen in the form of coordinate functions that satisfy the boundary conditions and the incompressibility condition. One of the found variable parameters was the rate of change of the initial eccentricity during the compression process, which determines the final accuracy of the wall thickness. The influence of the initial eccentric wall thickness variation and the magnitude of radial compression on the final accuracy of the wall thickness was studied. As a result, the characteristics of the final eccentric wall thickness variation were determined, as well as a normalized accuracy indicator, depending on the accuracy requirements in the regulatory documentation. To assess the level of accuracy on the Harrington scale, quality indicators were normalized in the interval from 0 to 1 corresponding to the required level of accuracy. An example of a calculation is given to predict the level of accuracy of a pipe with a given compression mode. The developed technique can be used to select rational deformation modes during pipe production to ensure the required level of wall thickness accuracy
Publisher
South Ural State University
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