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M

arch

2009

www.read-tpt.com

110

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.

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.

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.

Figure 5

:

The dependence of the reducing mill roll rpm on the tube diameter

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