JPS62168606A - Hot oil rolling method for strip - Google Patents

Abstract

PURPOSE:To additionally decrease the required electric power of a rolling mill by supplying a rolling mill oil in proportion to the rotating speeds of work rolls for each of rolling stands and controlling the rate of the rolling mill oil to be supplied in accordance with the actual coefft. of friction calculated from the forward slip of steel products. CONSTITUTION:The reference rate of the rolling oil to be supplied proportional to the rotating speed (v) of the rolling work rolls 1 is set by taking the slip limit determined from the actual operation into consideration for each of the rolling stands in hot oil rolling of the steel products 2. The actual coefft. of friction mu'' is then calculated from the forward slip (f) of the steel products 2 obtd. by the actual measurement. Said coefft. is compared with the coefft. of friction mu' of the slip limit determined from the actual operation to determine DELTAmu=mu'-mu''. The correction rate DELTAq of the oil to be supplied corresponding to the above-mentioned DELTAmu is determined from the relations among the coefft. of friction mu, the rate (q) of the oil to be supplied and the rotating speed (v) of the rolls. The above-mentioned reference rate of the oil to be supplied is corrected in accordance with the DELTAq and the rotating speed of a motor 5 for an oil pump 4 is controlled. The rate of the oil to be supplied is thereby controlled to attain an optimum coefft. of friction and the economization of energy is attained.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a hot hydraulic rolling method for strip, and aims to save energy by optimally controlling the supply amount of rolling oil for each rolling stand. .

(Prior art) In hot rolling, a hot hydraulic rolling method is known in which rolling oil is supplied to rolling rolls for the purpose of reducing roll wear, reducing rolling load, and improving the surface properties of rolled materials. . This method utilizes the reduction in the coefficient of friction between the steel material and the roll due to the lubricating effect of rolling oil.

Japanese Patent Publication No. 52-462 discloses that different rolling oils are supplied to the first and second half work rolls of a finishing rolling mill group,
It discloses a technology that stabilizes hot rolling operations and significantly extends the life of each rolling mill roll.

(Problems to be Solved by the Invention) As mentioned above, hot hydraulic rolling aims at reducing the coefficient of friction μ between the steel material and the rolls due to the lubrication effect of rolling oil. Therefore, in order to improve the lubrication effect, it is desirable to increase the amount of oil as much as possible within a range that does not cause slip, but the friction coefficient μ varies for each stand depending on the steel material, temperature, surface properties of the rolls, etc. In addition, the rolling position from the beginning to the end of the rolling schedule changes from moment to moment.
Conventionally, it has been difficult to quantify this μ, so the amount of oil in each stand has been determined uniformly based on experience, and the amount of oil has not been adjusted for each stand. Therefore, sufficient effects could not be obtained from the viewpoint of energy conservation.

The present invention aims to further reduce the electric power required for the rolling mill by improving the darning points.

(Means for Solving Problem 7) The present invention supplies rolling oil to each rolling stand in proportion to the number of rotations of the rolling work rolls, and further measures the advance rate of the steel material and uses this to determine the relationship between the steel material and the rolls. This hot hydraulic rolling method for strip is characterized by calculating the actual coefficient of friction between the rolling stands and controlling the supply amount of rolling oil for each rolling stand based on the calculation results.

(Function) There is a relationship between the friction coefficient μ between the rolling work roll and the steel material and the supply amount of rolling oil, such that μ decreases as the oil supply amount increases, as illustrated in FIG. This is a roll-
This is thought to be because μ decreases as the oil film thickness between the steel materials increases.

FIG. 3 shows a case where the number of rotations of the work rolls is constant, but in hot rolling, the rolling speed of the subsequent stand increases, and the rotation speed of the work rolls also increases.

It is thought that the oil supplied to the work roll completely disappears while the work roll makes one revolution and comes into contact with the steel material.

Therefore, in order to control μ to the target value in each rolling stand, the basis of control is to supply rolling oil in proportion to the number of rotations of the work rolls in each stand. In the present invention, first, a reference oil supply amount proportional to the work roll rotation speed of each stand is set in consideration of the slip limit determined from actual operation. This is illustrated in FIG.

Next, in order to further reduce this μ as much as possible within the range where no slip occurs, the actual value μ'' is calculated and the oil supply amount is corrected.

The advance rate f is calculated from the steel exit speed ■5 and the roll circumferential speed VR: f = (V s VR) / V n
...defined by (1). Here (1)
Multiplying the denominator and numerator of the equation by the transit time t between the stands of steel material from i to (i+1) gives f = V, ・t/V, ・t−i=l
S/IR-1 (2) where IS: distance between stands, IR two-roll rotation.

There is the following relationship between the advance rate and the friction coefficient μ.

According to Siebel, the f-μ characteristic for sliding friction is given by the following equation.

f = (0,5-0,25/Z 0)2-ξO"
'(3) Zo"μJ positive 7fu~mouth infection...(
4)ξ. =r/(1-r)...(
5) R': Flattening roll radius, Δh: Reduction amount, r: In the area where the reduction rate is fixed, the theory of Sims (S 1m5) is extended and simplified to the case of tension, and f = 0.23r-0.5Ah/R'・Db '4
)/Kf+n...(6) σ,: Back tension, σ,: Front tension, K fn+: Average deformation resistance.

Numerical calculation results based on Oroman's theory for mixed friction are subjected to multiple regression in Siebel form, and the extension to tension is found in the form of Sims' equation, and f-
Obtain the μ characteristic formula.

f = (0,4551 dark stone] - Kueting - o, 2337p -r/-v7TE = -r->-Jπ
in/R')2...(7) Hin: Rolling machine entrance side thickness It becomes possible to calculate the actual performance μ from the advance rate f by back-calculating the formula (7).

This actual performance μ'' is compared with the slip limit μ' obtained from actual operation to obtain Δμ=μ'-μ''.

From FIG. 3, the following equation generally holds true between μ, oil supply amount q, and roll rotation speed V.

μ= −k+ (qo/v) 10L
(8) Therefore, control is performed by determining the oil supply correction amount Δq corresponding to the previously determined Δμ based on equation (8).

(Example) As shown in FIG. 1, for example, the method of the present invention provides an oil pump 4 whose flow rate can be controlled by a motor 5 in each rolling mill stand, and in each stand, the roll outlet speed of the steel material and the roll This can be carried out by measuring the circumferential speed, calculating the advance rate f, and controlling the flow rate of the oil pump 4 based on the result.

(Effects of the Invention) According to the present invention, the standard oil supply amount is determined for each stand by considering the rotation speed of the two-roll in each stand, and the actual oil supply amount is determined based on the advanced rate without considering the steel material, temperature, etc. It becomes possible to calculate the M friction coefficient and control the oil supply amount so as to obtain the optimum friction coefficient.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of a calculation control device implementing the method of the present invention, t! Figure S2 is a diagram showing an example of the standard oil supply amount for each stand that is proportional to the rotation speed, and Figure 3 is a diagram showing an example of the relationship between the oil supply amount and the friction coefficient μ. 1... Work roll, 2... Steel material, 3... Oil tank, 4... Oil pump, 5... Motor.

Claims (1)

[Claims] (1) Supply rolling oil to each rolling stand in proportion to the number of rotations of the rolling work rolls, and further measure the advance rate of the steel material and calculate the actual coefficient of friction between the steel material and the rolls from this, and use the calculated result as A method for hot hydraulic rolling of strip, characterized in that the amount of rolling oil supplied is controlled for each rolling stand based on the following: