TPT March 2009

If the new hypothesis is used in the basic set of continuum mechanics equations, the multiplier will be replaced with where s s 0 is a free term of the linearized rheological equation. A numerical simulation of the stress-strain state On the basis of the setting problem of the refined continuum mechanics boundary-value, the object-oriented simulator and the numerical analysis software program for the hot tube reducing process were created. The use of this software is more convenient than the use of Deform, Marc and similar packages due to its comparatively narrow application. First of all, it is connected with the program-protected grid for splitting the deformation centre into finite elements (figure 4) and the minimal primary data input volume. The programme is primarily aimed at the analysis of the tube metal forming to define, for instance, limit values of frequent deformations that do not lead to appearance of internal surface facets. Design and application of tube deformation process models As was previously mentioned, there is a lack of software tools for computerized calculation of manufacturing process parameters, especially with an integrated description. As a result, a number of programs have been designed in the Borland Delphi integrated environment that can be used by production managers in plant conditions. One of these software products is a program for calculating speed behaviour as well as energy and power parameters of the hot reducing process. This software was designed for a specific reducing mill at Volzhskiy Tube Works and so its database has a maximum amount of information about this particular mill. For instance, databases that can be corrected (if required) contain information about the working stand inventory, pass parameters and reduction schedules.

 Figure 5 : The dependence of the reducing mill roll rpm on the tube diameter

Due to the existence of databases for reducing speed calculations, it is enough to enter dimensions of a finished tube and rheological coefficients of the worked metal. The results can be represented both in the form of tables, which is more customary to the plant staff, and in the form of graphs. The application of this software program in the plant conditions has enabled a dramatic reduction of the number of adjusted tubes. It has also established the reasons behind the diameter of thick-walled pipes being in the positive area of the tolerance field. Nevertheless, a significant influence of the tube diameter on speed was noticed during the simulation process (figure 5). The influence of pipe wall thickness on energy power parameters of the process were also studied (figure 6). Along with the software for the reducing mill setting, a software product for computerized development of the tube reducing technology was developed. This product is of a multipurpose nature and allows the development of reducing technology for two- and three-roll stands, with or without tension between the stands. An interface between the user and the computer is also possible and it allows the introduction of changes during the work with the program.  Figure 6 : The dependence of the force acting on rollers on the wall thickness of reduced tubes

 Figure 4 : Deformation zone diagram in the tube reducing process

 Figure 7 : Task window of the automated design programme for the pipe reducing technology

The technological para- meters necessary to receive tubes of the target size and require- ments are presented in the table form. Figure 7 shows an example task window that requires a minimal quantity of initial information for the program operation.

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M arch 2009

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