JPH04356315A - Cold rolling method - Google Patents

Abstract

PURPOSE:To perform rolling by using emulsion which can satisfy both stability in a supplying system of emulsion and play-out (water repelling and spreading) performance to show lubricating performance. CONSTITUTION:Rolling is performed by using emulsion having a distribution form of oil particles formed from oil particles in which the average particle diameter of oil content in emulsion as rolling lubricant is 6-15mum and the particle diameters of 50% of oil content are 6-15mum.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cold rolling method characterized by using a coolant emulsion having a particle size distribution within a certain range.

0002

[Prior art] The lubricant conventionally used in cold rolling is O/
It is supplied to the roll bite in the form of a W (oil-in-water) type emulsion, but the stability within the emulsion supply system and the plate-out (water syneresis) property to achieve lubrication performance are completely opposite. It is the direction.

[0003] In other words, in order to obtain a stable emulsion, it is necessary to make the oil particle size in the emulsion finer and deepen the emulsification, but in this case, the affinity between water and oil becomes strong and the ability to plate out onto the plate is impaired. As a result, lubrication performance deteriorates, roll flaws occur, and efficiency decreases.

On the other hand, if the oil particle size is increased, the plate-out property is improved, but the oil becomes more likely to float and separate in the system, resulting in uneven lubrication and plate thickness fluctuations due to chattering and unstable slitting. This causes the problem of higher unit consumption.

[0005] These phenomena are commonly experienced in cold rolling oil systems, but this tendency is more pronounced in circulation systems in which the supply system is large-scale than in direct systems. Therefore, how well these contradictory phenomena are controlled within an appropriate range will determine whether stable, highly efficient, and high-quality products can be produced.

[0006]

[Problem to be Solved by the Invention] Conventionally, emulsification of coolant emulsions has been carried out by adding surfactants, mechanical stirring, etc., but until now, the emulsions have conflicting effects on lubricity and stability as described above. There is no quantitative index for satisfying the two properties, and the state of emulsification has been merely empirically measured visually or with some kind of particle size measuring device as a guideline for operation.

[0007] Furthermore, as shown in Figure 1, it is difficult to obtain quantitative indicators using only surfactants, which are conventional emulsifiers, or mechanical stirring because the oil particle size distribution is wide and the peak is weak. Further complicating the problem was its difficulty and the fact that it was highly influenced by changes in temperature and changes over time.

Therefore, in order to control these contradictory phenomena within an appropriate range, it is necessary to keep the particle size distribution of the oil particles forming the emulsion within a certain range, and to control disturbances such as the magnitude of mechanical stirring and changes over time. An emulsifying and dispersing agent that is less susceptible to oil particles and that can control the particle size of oil particles is needed.

As a result of our research, the present inventors have developed an emulsifying and dispersing agent that satisfies the above characteristics, for example, in Japanese Patent Application No. 56-204623.
The dispersant disclosed in No. 56.12.18 was successfully developed.

[0010] This invention was made in view of the above-mentioned circumstances, and its purpose is to create an emulsion in which the particle size distribution of oil particles forming the emulsion is always within a certain range in the tank, pump outlet, and header. It is an object of the present invention to provide a cold rolling method that enables stable operation with high efficiency and high quality by rolling using a cold rolling method.

[0011]

[Means for Solving the Problems] In the cold rolling method of the present invention, an emulsifying dispersant is added so that the average particle size of the oil in the emulsion is always 6 to 15 mm in the tank, pump outlet, and header.
μ and at least 50% of the oil particles have a diameter of 6 to 15 μm, and the emulsion concentration is 1 to 5 μm.
%, and is characterized by rolling using this emulsion as a rolling lubricant.

0012

[Operation] By rolling using an emulsion having a distribution form of oil particles in which 50% or more of the oil content in each part of the emulsion as a rolling lubricant is formed by oil particles having a diameter of 6 to 15 μm. It is possible to produce high-efficiency, high-quality products with stable rolling operations, with little oil flotation (loss) to the scum, and with excellent rolling oil consumption.

[0013]

EXAMPLES The results of various experiments conducted to determine the appropriate average diameter and distribution form of oil particles in an emulsion will be described below.

FIG. 2 shows an example of the average particle size and particle size distribution of oil particles in an emulsion using the emulsifying dispersant developed by the present inventors. This has an extremely sharp particle size distribution compared to the conventional one shown in FIG. 1, and the distribution is stable in each part of the circulation system. That is, the average value of the particle size is also 12 to 14μ.
It is stable, and the particle size distribution is 6 to 15μ, which is more than 50%.

FIG. 3 shows emulsions A (average particle size 15 μm, 50% particle size 6-15 μm) and B (average particle size 9 μm, 55% particle size 6-13 μm) of the present invention, and a conventional emulsion. This figure shows the results of investigating the relationship between the concentration at the pump outlet side and the amount of adhesion using C (average particle size: 7 μm, and 35% particle size from 3 to 15 μm). The particle size distribution of each emulsion in this case is shown in FIG.

In the case of the conventional emulsion C, the width of the particle size distribution is wide as shown in FIG. 1, so even when an emulsion of a constant concentration is sprayed, there is a large variation in the amount of adhesion. On the other hand, in emulsions A and B of the present invention, as shown in FIG.
The particle size distribution of ~15μ is sharp, and the average particle size is also stable at 9 to 15μ, so the plate-out property of the emulsion is stable, and the correlation between concentration and adhesion amount is easy to reproduce. It has strong lubricity, and the lubricity can be controlled by concentration.

Next, FIG. 5 shows the relationship between the average particle diameter of the oil in the emulsion of the present invention and the rolling force per unit width as lubricating performance. This shows the relationship between the rolling load in the fifth stand of the tandem mill and the average particle size by changing only the average particle size of an emulsion whose oil particle size distribution satisfies the requirements of the present invention. It is.

[0018] In this case, if the average particle size is less than 6μ,
Due to poor plate-out properties, the lubrication performance suddenly decreased and the rolling force increased. On the other hand, if it exceeds 15μ, excessive lubrication occurs, reducing the rolling force and causing chattering and unstable slipping. Figure 6 shows the Huon
This is a plot of the relationship between the average friction coefficient within the roll bite and the average particle diameter of the emulsion, which was calculated using Kalman's differential equation.

In FIGS. 5 and 6, the average particle diameter is 6 μm.
If it is less than that, roll defects occur frequently because the oil particles become too small and the plate-out property deteriorates, resulting in burn-in defects called heat scratches. Also, when the average particle diameter exceeds 15 μm, gauge fluctuations occur frequently due to chattering and slip caused by an excessive amount of plate out. Here, those with an average particle diameter of less than 6 μm and those exceeding 15 μm did not satisfy the requirement of the present invention that “50% or more of the oil content consists of particles with a size of 6 to 15 μm”. FIG. 7 shows the results of investigating the relationship between the average particle diameter and the plateout amount using the emulsion used in the rolling shown by the plots in FIGS. 5 and 6.

FIG. 8 shows an example in which the average particle diameter is 6, in order to analyze in more detail the difference between the present invention and the prior art shown in FIG.
This was obtained as a result of investigating the ratio of particle diameters of 6 to 15 microns in the oil contained therein and the variation in the amount of plate-out in emulsions with a particle diameter of micron or larger. That is, FIG. 3 is a comparison of the average particle size of oil based on the concentration, and a more detailed view of the particle size distribution and the variation in the amount of adhesion. From this, it was found that when the ratio of particle diameters of 6 to 15 microns was less than 50%, the variation in the amount of adhesion rapidly increased.

From this, it can be seen that not only the average particle diameter of the oil in the emulsion is 6 to 15 μm, but also the distribution of oil particles in which more than 50% of the oil content is formed by oil particles having a diameter of 6 to 15 μm. It has become clear that unless an emulsion having a certain shape is used, the amount of adhesion increases and a stable amount of adhesion cannot be obtained. In addition, when particle sizes vary, when looking at microscopic lubrication performance, there are localized areas with excellent lubrication and areas with insufficient lubrication, which can easily cause unstable slips. Heat scratches are likely to occur in some parts, making stable operation impossible.

[0022]

[Effects of the Invention] This invention was obtained by comprehensively examining the various experimental results mentioned above.
In addition, by rolling an emulsion with an oil particle distribution form in which 50% or more of the oil content is formed by oil particles with a diameter of 6 to 15 μm, floating separation (loss) of the oil content into the scum is reduced. , and can produce high-efficiency, high-quality products through stable rolling operations.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the average value and particle size distribution of oil particles in a conventional emulsion.

FIG. 2 is an explanatory diagram showing the average value and particle size distribution of oil particles in the emulsion of the present invention.

FIG. 3 is an explanatory diagram showing the relationship between emulsion concentration and adhesion amount of emulsions of the present invention and conventional emulsions.

[Figure 4] Particle size distribution diagram of the present invention and conventional emulsion (
Particle size distribution diagram in Figure 3).

FIG. 5 is an explanatory diagram showing the relationship between the average particle diameter of oil particles in an emulsion and the rolling force per unit width.

FIG. 6 is an explanatory diagram showing the relationship between the average particle diameter of oil particles in an emulsion and the coefficient of friction.

FIG. 7 is an explanatory diagram showing the relationship between the average particle diameter of oil particles in an emulsion and the amount of adhesion.

FIG. 8 is an explanatory diagram showing the relationship between the proportion of emulsion oil particles having a particle size of 6 to 15 μm in the total and the amount of adhesion.

Claims (1)

[Claims] Claim 1: Adding an emulsifying dispersant to the oil in which the average particle size of the oil in the emulsion is always 6 to 15 μm in the tank, pump outlet, and header, and 50% or more of the oil particles have a diameter of 6 to 15 μm. A cold rolling method characterized in that the emulsion is formed of particles, the emulsion concentration is 1 to 5%, and rolling is carried out using this emulsion as a rolling lubricant.