Predicting the accuracy of pipes at sinking

Abstract

Sinking is subjected to pipes after short-term drawing or rolling on cold rolling mills or roll rolling mills, ie pipes having a certain difference.
In order to assess the accuracy of pipes after sinking, technological routes of pipe production from different grades of steel were designed and investigated. According to the developed routes by the production technology, batches of tubes were drawn, samples were taken from each batch and wall thickness measurements were made at equally distant points of pipe cross-section.
For each passage of the drawing are calculated: absolute and relative difference of the work piece and the finished pipe, the coefficient of compression in diameter, the degree of thinness, the degree of deformation, the coefficient of change of the difference.
According to the results of measurements, correlation-regression analysis was performed, factors influencing the variation of difference were determined, and regression dependencies of the prediction of the expectation of the transverse difference of pipes at the block were constructed.
In the analysis of the dependences obtained, we can draw the following conclusions: the more plastic the metal, the smaller the difference in difference. Less plastic steels tend to change in diversity.
The intensity of the correction (<1) depends on the compression ratio in diameter - the greater the value of its value, the more intense the correction of the difference. That is, in order to correct the difference (> 4%) at sinking, it is necessary to increase the coefficient of drawing.
Conclusion. The results of the researches are incorporated into the calculations of routes and technological maps of production in order to predict the difference of finished pipes during drawing and to introduce a reduction of metal costs in production.