JPS6268607A - Method for controlling lubricating oil supply rate in cold rolling - Google Patents

Abstract

PURPOSE:To permit the adequate and automatic control of a lubricating oil supply rate for every coil unit by subjecting the reference supply rate of the lubricating oil determined from the functions of rolling force and rolling distance of cold rolling to correction with the coefft. of friction calculated from the values measured with a rolling force meter, etc. during rolling. CONSTITUTION:The reference supply rate R1 of the lubricating oil is determined by a control device 7 from the data on the rolling distance by the revolution pulses of a rolling motor 4 with regard with a cold rolling material 1 and work rolls 2 and the rolling force 5 measured with the rolling force meter 5. On the other hand, the coefft. mu0 of friction is calculated in a control device 8 by adding a steel kind, size, etc. to the approximation expression I of Hill by the stable rolling force P based on the experience on rolling. The lubricating oil supply rate R2 is calculated in the control device 8 by the equation II which subjects the coefft. mu of friction determined by the equation I from the rolling force 5 and revolution pulses 4 during the actual rolling of the coil and the tension correction term of the tension meter 6 to the addition with the correction term alpha for every stand. The oil is supplied at such rate from a flow rate control device 9. The lubricating oil supply rate for each coil is thus made adequate with regard to the reference coil of that steel kind and size, by which the product is stabilized.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention automates the supply of lubricating oil in cold rolling by using a coefficient of friction calculated from the actual rolling force, thereby reducing the complexity of equipment. This invention relates to a method for always obtaining stable rolling force by adjusting the lubricating oil supply amount to an appropriate value without causing

[Background of the invention]

As a method of controlling the supply amount of lubricating oil, a method has been considered in which the supply amount of lubricating oil is varied as a function of the product of rolling force and rolling distance. However, this control device did not include a function to automatically correct the calculated lubricant supply amount. Therefore, if an error occurs between the calculated feed amount and the feed amount required to obtain a stable rolling force, there is a problem in that the influence extends to the next and subsequent rolling operations.

In addition, in hot rolling, according to Japanese Patent Application Laid-Open No. 57-199501, a friction coefficient measuring device is added to each stand to measure the friction coefficient, and the supply amount of lubricating oil is adjusted based on the measured 7'c# friction coefficient. There are ways to do this. However, with this method, it is necessary to install a friction coefficient measuring device on each stand, and it is difficult to install this friction coefficient measuring device on current equipment that aims to simplify equipment and make maintenance easier. It's not a good idea. Furthermore, there is a problem in that there is a possibility that this friction coefficient measuring device may damage the orifice during rolling or when the plate of the material to be rolled is broken. This is a particularly important problem in cold rolling where roll scratches are immediately reflected on the rolled material.

[Purpose of the invention]

The purpose of the present invention is to calculate the friction coefficient from the value of the lubricating oil supply amount obtained as a function of the product of rolling force and rolling distance from a measuring device such as a rolling force meter, and use this friction coefficient to calculate the An object of the present invention is to provide a method for controlling the amount of lubricating oil supplied, which corrects the amount of lubricating oil supplied each time a coil is rolled.

[Summary of the invention]

The role of lubricating oil in cold rolling is to reduce the rolling load such as rolling force and rolling torque, to reduce wear on the rolls by reducing the load and extend the life of the rolls, and to cool the rolls and the rolled material. and smoothing the surface of the rolled material. Roughly speaking, in tandem rolling, stable high-speed rolling is only possible when the rolling forces of each stand are balanced, so it is necessary to always maintain the rolling force at which rolling is most stable, which has been determined from experience. . The rolling force is high immediately after the rolls are reassembled, and as the coil is rolled, the rolling force gradually decreases.As is well known, the roll surface is worn and the friction between the roll and the material to be rolled is the cause. This occurs because the coefficient becomes smaller. Figure 2 shows the relationship between the number of rolling rolls and the rolling force after the rolls were rearranged. In order to reduce this variation in rolling force and always maintain the rolling force at which rolling is most stable, which has been determined from experience, it is necessary to keep the coefficient of friction, which changes depending on the roughness of the roll surface, always constant. . Factors that affect the coefficient of friction include the amount and concentration of lubricating oil in addition to the roughness of the roll surface. Figure 3 shows the relationship between the amount of lubricant supplied and the coefficient of friction. The coefficient of friction can be reduced by increasing the amount of lubricating oil supplied, and the coefficient of friction can be increased by decreasing the amount of lubricating oil supplied. Similarly, by increasing the concentration of lubricating oil, the coefficient of friction can be decreased, and by decreasing the concentration, the coefficient of friction can be increased. However, since the lubricating oil tank is large, it takes too much time to change the lubricating oil concentration therein.

In order to solve this problem, it is conceivable to have multiple tanks with different lubricant concentrations, but in the present invention, we consider equipment with only one lubricant tank and vary the coefficient of friction depending on the amount of lubricant supplied. This section describes how to do this.

[Embodiments of the invention]

The content of the present invention will be explained below with reference to FIG.

In the figure, 1 is a material to be rolled that is rolled by a work roll 2 and a backup roll 3 that supports it. 4 is work roll 2
A pulse counter is attached to the electric motor that rotates the motor. 7 is a device that performs the following control. Determine the rolling distance of the work roll 2 from the pulses increased from the electric motor 4, input the rolling force from the rolling force meter 5, and calculate the standard supply amount R of lubricating oil from the function of this rolling distance and rolling force. This is the device you are looking for.

8 is a control device of the present invention. The tension is measured by the tension meter 6, the speed of the work roll is determined by the pulse input by the electric motor 4, the rolling force is calculated by the rolling force meter 5, and the standard supply of lubricating oil is calculated by the equipment fi17. Find the quantity.

The friction coefficient μ is calculated from the actually applied rolling force P using the following known approximation formula of )(ill).

P: Rolling force: Average deformation resistance r of the rolled material; Reduction ratio R': Flat roll radius H: Entrance plate thickness of the rolled material h: Output plate thickness b of l: width of l - actual tension correction term Based on our rolling experience, the coefficient of friction necessary to obtain the rolling force at which rolling is most stable is calculated in advance using equation (2), and is kept as a constant for each steel type and dimensional specification of the material to be rolled. This friction coefficient is μ. shall be. During rolling of the material, the actual rolling force P is input and the friction coefficient is calculated using equation 2). Let this friction coefficient be μ. FIG. 4 shows the relationship between the friction coefficient and the number of rolled sheets, which were determined using the rolling force shown in FIG. 2 and equation (2).

Assuming that the standard supply amount of lubricating oil inputted from the lubricating oil supply amount control device 7 is R3, the control system &8 of the present invention controls the supply amount R of lubricating oil as follows: R t = R, +α・
□ ...(3) R0 α is a correction term that is adjusted for each stand.

The friction coefficient μ obtained during actual rolling is the friction coefficient μ required to obtain stable rolling force. If it is larger, the amount of lubricating oil supplied will be increased, and if it is the opposite, the amount of lubricating oil supplied will be decreased.

This supply amount R is determined by the lubricating oil flow rate side slanting device 9 for each coil.
Output to. The lubricating oil flow rate side tilting device 9 includes a pressure regulating valve and a device for changing the rotation speed of a pump.

FIG. 5 shows the effect of the present invention. R8 indicates the lubricating oil supply amount output by the lubricating oil supply amount control device 17, and P
, indicates the rolling force at that time. R.

is the supply amount of lubricating oil after the supply amount of lubricating oil is corrected by the control ft8 of the present invention, and P2 represents the rolling force at that time. Po indicates the rolling force at which rolling is most stable, which was determined from experience. As is clear from the figure, when only the lubricating oil supply amount control device 7 is used, the control device 8 of the present invention
It would be better to add . It is expected that it will be close to .

〔Effect of the invention〕

According to the present invention, the amount of lubricating oil supplied can be adjusted on a coil-by-coil basis, and a predetermined rolling force can be obtained more accurately.

[Brief explanation of drawings]

Figure 1 is a system diagram of an embodiment of the present invention, Figure 2 is a diagram showing the relationship between rolling force and number of rolling rolls, Figure R3 is a diagram showing the relationship between friction coefficient and lubricant supply amount, and Figure 4 is a diagram showing the relationship between friction FIG. 5, which is a diagram showing the relationship between the coefficient and the number of rolling rolls, is a diagram showing the prediction of the present invention. P...Rolling force, R...Lubricating oil supply amount, μ-friction coefficient.

Claims (1)

[Claims] 1. In a method for controlling the supply amount of lubricating oil used to reduce friction occurring between a work roll of a rolling mill and a rolled material during cold rolling, the actual rolling applied to the rolling mill The method is characterized in that a force is input, a coefficient of friction occurring between the material to be rolled and the work rolls of the rolling mill is calculated, and the supply amount of the lubricating oil is controlled based on the calculated coefficient of friction. A method for controlling the amount of lubricating oil supplied during cold rolling.