In this article we will discuss about slab method and Ekulund’s formulation for determining rolling load in hot rolling of strip.
Slab Method for Determining Rolling Load:
The total rolling load or rolling force PT may by be determined by integrating px over the lagging and leading zones. Thus we can write,
Ekulund’s Formulation for Determining Rolling Load:
Ekulund gave an empirical formulation for determining rolling force for hot rolling of wide strips. It is given below-
Example 1:
A strip of 1000 mm width and 10 mm thick is hot rolled in a 4 high stand with working roll diameter of 600 mm to 7 mm thickness at an average temperature of 1050°C at a rolling speed of 4 m/sec. Determine the relative average roll pressure (pm/σ0) by different formulae given above.
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Let us first find out the co-efficient of friction μ. For the given rolling speed the value of k2 from (Fig. 7.5) is 0.8.
The value of pm/σ0 obtained by numerically integrating Eqns. (7.23) and (7.24) over the contact length is equal to 2.57252. All these values are very close. Therefore we may use Tselikov’s simplified formula safely.
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Example 2:
Determine the rolling load for rolling of slab 1000 mm wide and 400 mm high to 300 mm height at 1150°C in slab rolling stand with rolls of diameter 1150 mm. The rolling is done at 2m/sec. The yield strength of material at the given temperature is 86 N/mm2.
