Industry


possible to make contact forces smaller and to lessen consequent additional loads. Devices such as shock absorbers (with their variable stiffness using modern high energy capacity materials) are used in a lot of iron and steel works, and their use continues to grow.


Among the most successful and original design cases of commissioning and using shock absorbers inside the main rolling equipment, both technically and economically, are:


1) installation of polyurethane lining straps 9 and 10 instead of steel ones on chocks 3 of RR 2 (refer to figure 1) where the former have almost the same geometric design as the latter. During the design, the Finite Element Method (FEM) was used to carry out the stress analysis of the assembly of components 3, 9, 7, 12 and part of 6 (refer to figure 1). A horizontal force of 2 MN (450,000 lbf) was applied on the inner part of the rolling bearing of the chock 3 of lower RR 2. The interactions between contact surfaces, with different steel strength characteristics, of these parts with the same geometric design and measurements are as expected. Figure 2 shows the results of FEM stress analysis of the base assembly of components of the roughing hot thick-strip reversing four-high working stand of the Plate Mill Shop (PMS) 3000 of Pjsc ‘Ilyich Iron And Steel Works of Mariupol’ (hereinafter referred to as ‘Ilyich Works’). Calculating the von Mises yield stress (please see table on right) and the compression stress allowed the selection of the most appropriate polyurethane grade for the lining straps with a sufficient safety factor for their industrial use. The maximum compression of approximately 0.18 mm of the polyurethane-lining strap in the direction of the horizontal force is acceptable.


The significant reduction of von Mises yield stresses in components of the working stand was achieved by the use of a high-energy-capacity polyurethane lining strap on the chock of RR. If the energy capacity of the working stand with all steel parts and polyurethane lining strap is compared to the conventional steel system, an


28


Material of lining strap


Detail


Chock of lower RR (Steel 30ХГСФЛ. CIS State standard (SS) 977-75)


080 M 46. B.S. 970


Polyurethane ‘Adipren’ (CIS)


59,465 40,279


Facing strip (080 M 46. B.S. 970)


121,983 19,903


Body of HC for pressing lower RR (Steel 25Х2М1Ф. CIS SS 20072-74)


64,427 28,025


Frame (Steel 161 grade 430. B.S. 1504 (76))


49,952 32,098


Table – Maximum calculated values of von Mises yield stresses (MPa) in components of the roughing four-high working stand


improvement by a factor of ten is observed. This matches the theoretical reduction of generated loads, n, as given by:


Est


is the Elastic Modulus of steel; Epol


is the Elastic


Modulus of polyurethane.


lining straps (eight items) was installed on RR chocks of the roughing four-high working stand of PMS 3000 and it has been in use for more than 21 months showing a significant economic benefit. A Ukraine patent, number 42803, protects this solution. Polyurethane lining straps on RR and BR chocks of the other four-high working stands are expected to be fitted later.


A new set of polyurethane ‘Adipren’ grade


2) Installation of small shock absorbers on the base of the outer rings of rolling bearings. In general, rolling bearings assemblies are stiff


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