UNIVERSIDADE FEDERAL DE MINAS GERAIS - Biblioteca Digital ...
UNIVERSIDADE FEDERAL DE MINAS GERAIS - Biblioteca Digital ...
UNIVERSIDADE FEDERAL DE MINAS GERAIS - Biblioteca Digital ...
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ABSTRACT<br />
In this work the development of a methodology is presented for evaluation of the capacity of<br />
the mandrel grippers of the coilers of Sendzimir cold rolling mills. The grippers are<br />
mechanisms composed of bars with hydraulic performance, whose function is to fasten and<br />
grip the strip end at the start of the winding process and thus allow the application of tension.<br />
The methodology consists of the development of physical models built close to the real scale,<br />
which were submitted to experimental tests with the purpose of identifying the maximum<br />
tension of strip winding as a result of the contact arc of the strip with a cylindrical surface<br />
similar to the rolling mill mandrel. The model was also used to characterize the friction<br />
between the strip and the mandrel. Generally, the winding practice considers that the<br />
application of tension can only be started after the wrapping up of at least 1.5 turn of strip<br />
onto the mandrel, which generates a decline in physical performance in the rolling mills. The<br />
main objective of this work is to evaluate the capacity of the grippers of the mandrel keeping<br />
in mind the application of tension with less than a rolling of the strip wound up onto the<br />
mandrel. The methodology was applied in three experimental cases in which mandrel<br />
segments that are equipped with grippers from three rolling mills were used. The results of the<br />
winding tension measured in the physical model in function of the contact arc were shown<br />
close to those obtained in the analytical model. A viability analysis for the industrial condition<br />
was also carried out, in which the benefits reached with application of the methodology was<br />
demonstrated, bearing in mind the high contribution margin of flat steels. The adoption of this<br />
methodology will allow the evaluation of the capacity of other grippers projects in order to<br />
optimize the strip winding process.<br />
Key Words: mill, winding, mandrel, gripper, friction.<br />
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