Industry installation of the parts. In summary, it
is the increase of horizontal forces Fhor due to impacts of chocks 3 of RR 2 and 4 of BR 5 against frames 6 during rolling because of growing gaps ∆1
,∆2 and ∆3
between facing strips 7, 8 and lining straps 9, 10 and 11. Moreover, inside many modern rolling stands there are hydraulic cylinders (HC) 12 for pressing RR 2 to BR 5 in final design position as it is shown on figure 1 and figure 2. The contact surfaces on lining straps 9 and frames 6 are loaded by horizontal forces, which may deform them, adversely affecting their performance;
• Additional vibration loads. These appear in the main drives in the form of dynamic oscillations. They can arise from two main sources: √ from differences between the design and actual erection positions. √ from wear of main drive components, eg gaps ∆4
and ∆5 between contact surfaces of clutches 13 and spindles 14.
The purpose of this classification is to show that the key problems of increasing overall dimensions of elements are significant increases in loads leading to high wear, fatigue damage and accidental breakdowns. In practice, design engineers define the equipment in detail but cannot influence the accuracy of the assemblies and the wear of components, which frequently cause loads to increase. It is necessary to prevent these loads reaching dangerous levels by providing for shock absorbers to be installed from an early stage of the design. Several examples are given later.
Vibration absorption needs careful consideration. There is a need to understand them not as ‘force and load’ but as ‘kinetic and potential energies’. During an impact the kinetic energy of moving parts converts into the potential energy of deformation. In order to reduce loads arising from this conversion we need a shock absorber between interacting pieces of equipment to absorb and disperse energy as heat.
The results of theoretical and experimental research show contact force values of opposing parts of metalworking equipment depend on the stiffness of contacting parts: the greater the stiffness, the higher the contact forces. That, in turn, defines the required strength of parts and assemblies. By reducing the stiffness of contact pairs it is
Figure 1. Simplified combined view of hot thick-strip four-high working stand
Figure. 2. General view with solid mesh of parts of hot thick-strip four-high working stand
In the design, modernisation and repair of different types of mechanical equipment, it is often wrongly stated that ‘The larger the part is, the stronger it should be’
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