JPH07251209A - Method of adjusting rolling oil for cold rolling of steel products - Google Patents

Abstract

(57) [Summary] [Purpose] The amount of coolant added is adjusted to an optimum condition when thinly rolling a high deformation resistance material using a high viscosity rolling oil. [Structure] The concentration of rolling oil that reduces the maximum friction coefficient existing in the intermediate speed range is set, and the lubrication condition is set so that the friction coefficient is adjusted to be equal to or higher than the minimum friction coefficient that causes slip due to over-lubrication. Viscosity at ℃ 150
A method for adjusting rolling oil when cold rolling a steel sheet having a deformation resistance of a final rolling stand of 80 kg / mm ² or more using a rolling oil of cst or more to 0.5 mm or less,
When the rolling speed is in the range of 0 to 2000 mpm, the rolling speed range is set to the low speed range, the intermediate speed range and the high speed depending on the degree of change of the friction coefficient of the rolling oil with the change of the rolling speed for cold rolling the steel material. Separated into the speed range, after adjusting the friction coefficient of the rolling oil in the maximum friction coefficient area in the intermediate speed range of the rolling speed to the allowable maximum value, when passing through the intermediate speed range, reduce the friction coefficient of the rolling oil .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling oil used for lubrication between a work roll and a steel material or for cleaning a roll surface in cold rolling or temper rolling of a steel sheet, particularly when rolling at a high speed or The present invention relates to control of rolling oil used during cold rolling of steel sheets having high deformation resistance of special steel such as stainless steel and electromagnetic steel sheets, and particularly to adjustment of coolant concentration and supply amount in the rolling oil.

[0002]

In the cold rolling of steel products, the relationship between the friction coefficient of the lubricating oil for rolling and the rolling speed is such that the friction coefficient decreases due to the increase of the oil film thickness formed on the roll surface due to the increase of the rolling speed, On the other hand, it is known that there is a phenomenon of decrease and increase due to two factors: the friction coefficient increases due to the change in oil film properties due to the increase in the amount of heat generation due to the increase in rolling speed. The friction coefficient shows the maximum value, and thereafter shows the phenomenon that it decreases as the rolling speed increases.

Against this background, for the adjustment of lubrication by the lubricating oil for rolling, the rolling oil concentration is set so that the content of the expensive rolling oil in terms of concentration is as low as possible, and the coolant supply amount is suppressed to the necessary minimum. Need to be implemented.

In determining the concentration of rolling oil, the concentration is set to a value that is equal to or less than the maximum friction coefficient in the low rolling speed region and that is close to the maximum friction coefficient.

On the other hand, roughly dividing the coolant amount supply adjusting method, it is possible to distinguish between a rolling mill operating at a constant supply amount regardless of the speed and a rolling mill capable of increasing the supply amount as the rolling speed increases.

The applicant of the present application has conventionally proposed various systems as a system for supplying the lubricating oil for rolling in which the supply amount of the coolant increases with the increase in speed. For example, Japanese Patent Publication Sho 63
Japanese Patent Laid-Open No. 124-124 discloses that rolling oil and hot water are mixed immediately before the rolling oil header for each stand so that the coolant concentration of the rolling oil can be quickly changed for each group of two or more stands. There is.

Further, in JP-A-4-4916, a plurality of coolant storage tanks are provided in a circulation system pipe for circulating a coolant for reuse, and a pipe for collecting the coolant used for rolling according to concentration is provided in these pipes. It has been disclosed that the coolant of a predetermined concentration is selectively supplied by a valve adjustment from a dedicated supply system of a coolant that is connected to a coolant storage tank and adjusted to a predetermined concentration in each tank.

However, in the cold rolling of the recirculation system, in order to thinly roll a high deformation resistance material such as a stainless steel plate or an electromagnetic steel plate, it is necessary to meet the minimum plate thickness limit and to cool at a high speed. During hot rolling, it is necessary to reduce the friction coefficient during rolling in order to reduce the rolling load and prevent the occurrence of heat scratches in response to the decrease in oil film strength due to the increase in the temperature of the rolled sheet. The rolling oil itself is also limited.

Therefore, as a rolling oil for rolling or high speed rolling of such a high deformation resistance material, Japanese Patent Application No.
As in the -200372 application, a high-viscosity rolling oil using a synthetic ester having a viscosity of 150 cst or more at 40 ° C. as a base oil is used to increase the amount of adhesion to the plate, and as a lubrication condition setting with a coolant, Set a relatively high concentration to reduce the friction coefficient in the low speed range,
A measure is taken to increase the amount of coolant above the low speed range and to perform rolling.

Here, if the rolling speed and the friction coefficient show the maximum friction coefficient in the low speed region as in the case of the conventional knowledge, and the behavior of decreasing with the increase of the rolling speed is shown, the high-viscosity rolling oil having a relatively high concentration is simply used. The problem of cost burden of using a large amount of

However, rolling with such a high-viscosity rolling oil exhibits a behavior of rolling speed-friction coefficient which is different from the conventional one. Therefore, it is caused by insufficient lubrication in the intermediate speed range and excessive lubrication in the high speed range. There is a problem that chattering problems occur.

[0012]

The problem to be solved by the present invention is a measure for adjusting the amount of coolant added to an optimum condition when thinly rolling a high deformation resistance material using such a high viscosity rolling oil. To provide.

[0013]

Means for Solving the Problems In the present invention, when a special steel having a high deformation resistance such as stainless steel is tandem cold-rolled and a high-viscosity rolling oil is used, the rolling speed is
The present invention was completed based on the novel finding that the friction coefficient of rolling oil is maximized in the intermediate rolling speed range of 300 to 700 mpm and the rolling speed and the friction coefficient behave differently from the conventional one.

That is, the present invention sets the concentration of the rolling oil that reduces the maximum friction coefficient existing in the intermediate speed range, and further sets the lubrication condition that adjusts the state to a value equal to or higher than the minimum friction coefficient that causes slip due to over-lubrication. To set,
A rolling oil adjustment method for cold rolling a steel sheet having a deformation resistance of 80 kg / mm ² or more in a final rolling stand to 0.5 mm or less using a rolling oil having a viscosity of 150 cst or more at 40 ° C. But 0-2000m
Within the range of pm, the rolling speed range is divided into a low speed range, an intermediate speed range, and a high speed range according to the degree of change of the friction coefficient of the rolling oil with the change of the rolling speed for cold rolling the steel material,
After adjusting the friction coefficient of the rolling oil in the maximum friction coefficient region in the intermediate speed region of the rolling speed to the maximum allowable value,
When passing through the intermediate speed range, the friction coefficient of rolling oil is reduced.

Means for adjusting the friction coefficient of the rolling oil with the change in rolling speed to the maximum allowable value in the intermediate speed range is as follows:
Adopting a means to increase the coolant supply amount under specific conditions, and adopting a means to respond to the reduction of the rolling oil friction coefficient by reducing the coolant supply amount in the high speed range that is out of the intermediate speed range. it can.

Other means for adjusting the friction coefficient of rolling oil include means for adjusting roll diameter, roll roughness, rolling reduction, tension, etc. There is a limit.

As a concrete means for increasing the supply amount of the coolant under a specific condition, in the intermediate rolling speed range, the coolant flow rate is increased to increase the concentration of the rolling oil for re-succession during cold rolling. It is practically preferable to adjust the temperature to 1% or more, the coolant temperature in the range of 40 to 75 ° C., and the emulsion center particle diameter of the coolant to 3 to 10 μ.

[0018]

[Function] When a high-viscosity rolling oil is used, the friction coefficient of the rolling oil is maximized. By taking measures to reduce the friction coefficient of the rolling oil only in the intermediate rolling speed range, the amount of the coolant is minimized. And economical rolling becomes possible.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a coolant compounding amount control system in which the present invention is applied to a tandem rolling mill of the type in which a coolant is circulated.

[0020] In the figure, the rolling oil supplied to each stand 1 ₁ to 1 ₅ is recovered from the recovery pipe 2 into the dirty tank 3, the coolant contained therein pump 4, through the filter 5, clean tank 6 and is supplied to the rolling oil supply pipe 9 to each stand by the spray pump 8 by the control mechanism 7. The control mechanism 7 compares the material of the rolled material, the plate thickness, the plate width, the rolling speed based on the maximum rolling speed and the flow rate of the coolant with the input mechanism 71, and the relation pattern between the rolling speed and the coolant flow rate and the input. The control mechanism 73 controls the amount of coolant supply by this comparison, and the motor 74 that transmits this to the spray pump 8.

FIG. 2 shows a basic pattern of the friction coefficient of rolling oil and the rolling speed for obtaining the relationship pattern between the rolling speed and the flow rate of the coolant in FIG.

In the pattern shown in FIG. 1, a rolling oil prepared by adjusting the coolant to an applicable temperature range of 40 to 75 ° C. and mixing it with warm water so that the central particle diameter of the emulsion is in the range of 3 to 10 μ is shown in FIG. With the tandem rolling mill consisting of the five stands shown, the rolling coefficient for electromagnetic steel having a deformation resistance of 80 kg / mm ² was rolled to a thickness of 3.0 mm to 0.5 mm. ~ 2
The change in friction coefficient when changed to 000 mpm is shown.

In the figure, curve A shows the change in friction coefficient when a low-viscosity rolling oil having a viscosity of 40 cst at 40 ° C. is used, and curve B has a viscosity of 18 at 40 ° C.
The change of a friction coefficient when using 0 cst high viscosity rolling oil is shown. In each curve, the state when the supply amount of the coolant is constant is shown by A1 and B1 by the solid line, and the state when the ratio of the coolant / rolling speed is constant is shown by A2 and B2 by the dotted line. Show.

In the figure, the upper X region is the Ford
As is widely known as the & Alexsanda-Stone equation, it indicates a critical region where lubrication is insufficient due to insufficient lubrication at the minimum plate thickness, and the lower Y region is
It shows the danger area where slippage occurs with the plate due to over-lubrication.

As shown in the figure, in the case of the A curve using a low-viscosity rolling oil, it has been used as an effective means which has been conventionally practiced because of the effect of lowering the friction coefficient due to the rolling-in effect of rolling oil. The maximum value is the large friction coefficient in the low speed range, and the lower limit is the value that does not cause chattering in the friction coefficient at high speed. I've been

On the other hand, the B curve using high-viscosity rolling oil is
This is a fundamental new finding for completion of the present invention, and in the low speed range I, the friction coefficient slightly increases as the rolling speed increases without entering the lubrication insufficient area X. Is extremely increased in the intermediate speed region II of 300 to 700 mpm, enters the lubrication insufficient region X, and further enters the high speed rolling region III in which the rolling speed exceeds 700 mpm, the friction coefficient of the rolling oil is in a substantially vertical state. Lowers. This is because in the case of high-viscosity rolling oil, the region where the maximum friction coefficient is taken is not in the low speed region but in the intermediate speed region, and because the friction coefficient decreases with increasing speed, the concentration of rolling oil, that is, the coolant By controlling the addition amount, it is not possible to cope unless the range of the friction coefficient is expanded.

That is, with the conventional concentration setting that covers the friction coefficient in the low speed region, the large friction coefficient in the intermediate speed region cannot be covered, causing the chattering phenomenon associated with the minimum plate thickness limit and causing the plate breakage. The productivity cannot be increased because it cannot be generated or the rolling speed cannot be increased.

Further, in the method of increasing the coolant flow rate with increasing concentration and the concentration that covers a large friction coefficient in the intermediate speed range, it is impossible to prevent chattering due to slipping due to friction coefficient decrease due to excessive lubrication in the high speed range.

That is, it has been found that in the conventional coolant supply system, chattering is caused in one of the upper and lower regions of the friction coefficient, which leads to the suppression of strip breaking and rolling speed.

FIG. 3 shows the comparison mechanism 72 shown in FIG. 1 based on the curve B of FIG. 2 when this high viscosity rolling oil is used.
The control pattern set to is shown.

The control pattern is such that the top of the curve B2 of the friction coefficient in the intermediate rolling speed region II is the coolant whose upper limit is defined by the maximum coolant supply amount in accordance with the installed capacities of the clean tank 6 and the spray pump 8 in FIG. Curve E2 determined by the relationship between quantity and rolling speed
On the basis of the above, the E1 curve is set so as to avoid the insufficient lubrication limit region X and the dangerous region Y where slip occurs between the plate material due to over-lubrication, and the supply amount thereof is controlled based on this.

[0032]

The present invention has the following effects.

(1) By using a high-viscosity rolling oil, it becomes possible to carry out rolling at high speed when thinly rolling a steel material having high deformation resistance.

(2) Since the coolant supply amount is increased only within a specific rolling speed range, the coolant consumption amount can be minimized, which is economical.

(3) When high-speed rolling of steel material having high deformation resistance is performed, even when slip occurs due to over-lubrication in the high-speed region due to roll roughness reduction after roll reshuffling, adjustment is made by the coolant supply amount. Therefore, it is possible to deal with the same level of reassembling frequency as ordinary steel.

(4) Plate breakage, roll damage, and product defects due to chattering at the upper and lower limits of the friction coefficient can be prevented.

[Brief description of drawings]

FIG. 1 illustrates a coolant supply control system for implementing the present invention.

FIG. 2 is a diagram for comparing the relationship between the rolling speed and the friction coefficient depending on the viscosity of rolling oil.

FIG. 3 is an explanatory diagram of a basic pattern for adjusting the coolant supply amount according to the present invention.

[Explanation of symbols]

1 Stand of rolling mill 2 Collection system of used rolling oil 3 Dirty tank 4 Pump 5 Filter 6 Clean tank 7 Control system 71 Data input mechanism 72 Control pattern comparison mechanism 73 Motor control mechanism 74 Motor

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location C10N 40:24 Z (72) Inventor Tamio Fujita No. 1 Hibatacho, Tobata-ku, Kitakyushu, Fukuoka New Nippon Steel Co., Ltd., Yawata Works

Claims (2)

[Claims] 1. The rolling resistance of the final rolling stand is 80 kg using rolling oil having a viscosity of 150 cst or more at 40 ° C.
/ Mm ² or more is a method for adjusting rolling oil when cold rolling a steel sheet to 0.5 mm or less, wherein a rolling speed is within a range of 0 to 2000 mpm, and a rolling speed for cold rolling the steel material. The rolling speed range is divided into a low speed range, an intermediate speed range and a high speed range according to the degree of change of the friction coefficient of the rolling oil according to the change of Is adjusted so that the maximum allowable value, and then the friction coefficient of the rolling oil is reduced in the high speed range. 2. The rolling oil adjusting method according to claim 1, wherein the friction coefficient adjusting means changes a supply amount of the coolant to the rolling oil.