Improvement of methodology and development of software calculation of routes production of pipes by sink drawing taking into account accuracy

Abstract

For designing routes of sink drawing pipes a certain assortment it is necessary to choose correctly the initial sizes of preparation, to calculate admissible deformations on diameter and a wall. Sink drawing to pipes after short-drawing drawing or rolling on cold rolling mills, ie pipes having a certain difference.
When designing routes to drawing it is necessary to predict in advance the size and direction of change wall thickness. The analysis of influence and its character for each parameter on change of wall thickness is carried out. Taking into account the analysis and the nature of the identified dependences, tested the construction of multiple linear and nonlinear regression to determine the wall thickness of the workpiece by , , , , .
To order to assess the accuracy of the pipes after sink drawing, technological routes of pipes production from carbon steel grades were developed 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.
According to the results of measurements, correlation-regression analysis was performed, factors influencing the variation of difference were determined and regression models were built.
With a small diversity of the workpiece (less than 3%) the diversity of the finished pipes increases, with a diversity of the workpiece 3 ... 4% the diversity of the finished pipes changes little and > 4% the diversity of the finished pipes decreases.
The intensity of the correction ( <1) depends on the compression ratio in diameter : the larger the value , the more intense the correction of the difference. That is, to correct the difference ( >4%) in the sink drawing, it is necessary to increase the coefficient of extraction.
The results of research are introduced into the calculations of routes and technological maps of production in order to predict the diversity of finished pipes during drawing and supplemented the software for determining the size of the workpiece when designing routes for drawing carbon cold-formed pipes by sink drawing.