TPT March 2009

New solutions for simulation of hot and cold tube rolling processes Mr A Vydrin, OJSC RosNITI, Russia

Introduction The issues of plasticity in metal working simulation have long attracted the attention of researchers. Simulations are divided into physical and mathematical, with computer simulation considered a modern form of the latter. The theoretical foundations for mathematical simulation of rolling processes were laid in the second half of the 20th century. This was the period when the majority of calculation formulas were obtained based on the fundamental laws of physics, but with a number of assumptions and simplifications to ensure analytical solutions. The end of the 20th and the beginning of the 21st century saw the development of computer technology and the new methods of numerical mathematics. Universal application software packages were developed, including Deform, Ansys, Copra, Forge3, and Marc, that allow numerical simulations of stress-strain and temperature conditions of metal during its plastic working phase. However, many researchers agree that the application history of this software used by technologists and laboratory staff shows its ineffectiveness in plant conditions. The reason behind it is laborious preparation of source data and long a time (up to one day or longer), required for the computing of one option, which effectively turns it into a research project. On the other hand, the use of analytical relations for technological calculations does not always produce sufficiently reliable results that will not require further technological development in plant conditions. The two main reasons for this are as follows: • A wide range of steel grades and sizes leads to the excessive laboriousness of technological parameter calculations for each combination of grade, type and size

 Figure 2 : Stress condition pattern of the tube reducing mill of a new design

• In a comprehensive approach, the task is usually described by a set of nonlinear algebraic equations that are difficult to solve without using numerical method and computers. Nowadays in the area of plastic metal working simulation, particularly in tube and pipe manufacturing, there are a limited amount of software tools for implementing modern calculating methods that base on analytical relations of plastic metal working processes. Currently, OJSC RosNITI is developing a comprehensive approach to the issues of simulation that will encompass virtually all research trends and types of simulation. The solution of production problems (eg those connected with metal forming), requires dealing with a hypotheses of the physical nature, which in most cases involves correctness that can only be proved with the help of computer simulation. The software system Deform- 3D is used for this purpose in cooperation with the Department of Plastic Metal Working of Yuzhno-Uralsky State University. Defining the strained condition of the plate edge when forming helical-seam pipes is one of the tasks that can be solved with the assistance of software. The simulation results have proved the existing hypothesis on the origins of ‘bamboo’ flaw (figure 1) observed in the formed pipe weld seam area. Practice has shown that the application CosmosWorks, part of the SolidWorks system, is an effective tool for simulation of structural components of the equipment working in the elastic stress zone. The use of this application is advisable for the performance analysis of complex configuration non-standard equipment when the existing analytical methods cannot be used without serious simplifications and assumptions. This software was also used to analyse strength The use of turnkey application program packages

 Figure 1 : Stress condition pattern in cylinder shaping

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M arch 2009

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