JPH0234203A - Method for cold rolling steel sheet - Google Patents

Abstract

PURPOSE:To reduce friction coefficient by performing a composite plating for which solid fine particles having a hardness not lower than a specific Vickers hardness are dispersed on the surface of a work roll by using hard Cr, etc., as a matrix and cold rolling a rolled steel sheet with neat oil or an emulsion of water and oil spraying onto the sheet. CONSTITUTION:A composite plating is applied onto the surface of a work roll by using Ni, Ni-P, Cu, hard Cr, Fe, Co or Ni-Co as a matrix. The composite plating is such that one or more kinds of solid fine particles having a Vickers hardness of >=900 are dispersed in the plating layer. Cold rolling is performed by the work roll and spraying neat oil or an emulsion of water and oil onto a rolled steel sheet. At the time of contacting the sheet with the roll surface, actual contact is generated between the sheet and solid fine particles on the outermost surface. Hence, a friction coefficient between the sheet and roll is reduced, service life of the roll is prolonged as well as high speed rolling is performable without making surface quality of the sheet worse.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention improves wear resistance and extends the life of the work roll by modifying the surface of the work roll when cold rolling steel sheets. By reducing the coefficient of friction between the rolls and the steel plate, it is possible to roll the steel plate without using highly lubricating rolling oil, and the surface quality of the product, especially the gloss required in rolling stainless steel plates, can be improved. In order to improve the properties, it is possible to roll using a rolling lubricating oil with low viscosity, which does not necessarily have good lubricity, or to roll at a warm temperature like silicon steel, or even to roll at high pressure and high speed with ordinary steel. The present invention relates to a method for cold rolling a steel plate, which can suppress the occurrence of surface abnormalities such as seizure even when rolled at high speeds.

[Prior Art] In cold rolling of a steel plate, the steel plate is generally cold rolled while being sprayed with a rolling lubricant. As the rolling lubricant, mineral oil, synthetic ester of beef tallow 9, an emulsion in which a lubricating oil having both lubricating and cooling effects is dispersed in water, or a mixture of two or more of these are used.

The material of work rolls generally used in cold rolling is C.
Made of high carbon steel with additions of R, Mo, V, Ti, etc., it is heat treated to increase the hardness from 80 to 90 degrees Shore, and the surface is polished to various roughnesses according to product specifications.
Alternatively, it is tulled by shot blasting or electrical discharge machining.

When ordinary steel is cold rolled using this work roll, natural oils and fats such as beef tallow and palm oil are generally used as the lubricating oil. However, these lubricating oils remain attached to the surface of the steel sheet after cold rolling and cause significant contamination of the surface during annealing in the subsequent process. For this reason, currently, an electrolytic cleaning process must be performed after the cold rolling process to remove lubricating oil remaining on the surface of the steel sheet before annealing.

In addition, for rolling difficult-to-process materials such as stainless steel and silicon steel, Sendzimer mills with small diameter work rolls or tamps and mills with large diameter work rolls are used. The lubricating oil for rolling by this Sendzimer mill or tandem mill is a low viscosity mineral oil to which a small amount of synthetic ester is added, either neat or as an emulsion. Generally, when cold rolling stainless steel, lubricating oil with low viscosity is used to improve surface gloss, so rolling lubricity is not necessarily good, and surface abnormalities such as seizure may occur during high-pressure, high-speed rolling. It becomes a problem. In addition, since cold rolling of silicon steel is generally warm rolled to reduce deformation resistance and improve electromagnetic properties, surface abnormalities such as seizure often occur, similar to cold rolling of stainless steel. .

Furthermore, when ordinary steel is cold-rolled under high pressure, the amount of heat generated within the roll bite is large, which poses a problem of occurrence of surface abnormalities such as seizure. In order to perform high-speed stable rolling without causing seizure, a lubricating oil with excellent lubrication properties that reduces the coefficient of friction between the roll and plate during rolling is required.

[Problems to be Solved by the Invention] However, surface gloss, ensuring stable rolling at higher temperatures or high reduction rolling, and lubrication properties are contradictory properties, and current lubricating oils cannot achieve surface gloss.

No material has been developed that is excellent in both high temperature stability or high pressure resistance and lubrication properties.

Therefore, in order to solve these problems, the present invention prevents surface abnormalities such as seizure by modifying the surface of the work roll and reducing the coefficient of friction between the work roll and the steel plate. Enables high-speed stable rolling 1. Surface gloss,
The object of the present invention is to provide a method for cold rolling a steel plate, which makes it possible to obtain products with excellent surface quality by using a lubricating oil with excellent high temperature stability or high rolling reduction properties.

[Means and effects for solving the problems] The present invention provides Ni, Ni-P on the surface of the work roll.

Composite plating is performed using Cu, hard Cr, Fe, Co, and Ni-Co as a matrix, in which one or more types of solid particles with a Vickers hardness of 900 or more are dispersed, and using the work roll, neat plating is performed. This is a method of cold rolling a steel sheet, which is characterized by cold rolling while spraying oil or an emulsion of oil dispersed in water.

FIG. 1 shows a schematic cross-sectional view of the vicinity of the surface of a work roll that has been subjected to composite plating. When a steel plate comes into contact with a work roll having such a structure, true contact occurs at the part of the solid fine particles on the outermost surface of the work roll.

The solid particles are harder than matrix plating, and the surface pressure during rolling is supported by the solid particles. As a result, a lubricating film is formed between the fine particles, and the amount of lubricating oil supplied to Roll High 1 is larger than that of conventional rolling work rolls, and the contact area is reduced, which is effective in reducing the coefficient of friction. There is.

The metal used for matrix plating can be arbitrarily selected depending on the environmental conditions in which the rolling work roll is used, and it is necessary to select a metal that has excellent adhesion to the work roll base material. ,Ni-P,C
u, hard Cr, Fe, Co and Ni-Co are considered optimal.

Regarding the solid fine particles of the dispersion material, it is desirable that the fine particles have a hardness higher than that of conventional cold rolling work rolls (Vickers hardness of 900 or more) in order to improve wear resistance (for example.

SiC, 5jJn, AQ203. SiO□, TiCJC
) When used as a dispersing material, there is no problem even if one or more types of these fine particles are mixed into the plating film at the same time.

The object of the present invention is to improve the lubrication properties by surface modification of work rolls and to improve the surface quality of products using a lubricating oil with excellent surface gloss, high temperature stability, or high pressure reduction properties. Composite plating includes electrolytic and electroless methods. However, in aiming to improve the surface quality, the method is not wood-like and does not need to be particularly limited in the present invention.

The lubricating oil used when performing cold rolling using composite plated work rolls is also effective in improving the surface quality of the product, such as gloss, high temperature stability, and high reduction properties. A suitable lubricating oil may be used as appropriate. For example, to improve gloss, the viscosity is 50cs at 40℃.
It is best to use a lubricating oil that is less than t.

The neat oil sprayed onto the work roll or the oil used in the emulsion is preferably mineral oil, natural oil/fat 9 synthetic ester, or a mixture of two or more thereof. Also, regarding steel plates to be subjected to cold rolling, in addition to ordinary steel plates, stainless steel plates and silicon steel plates can be mentioned.

[Example] Example 1 Ni-p+SiC on a link-shaped test piece assumed to be a work roll
Composite plating was applied and a friction test was conducted. The test piece ring had a size of φaox lhs+, was made of forged steel roll material for cold rolling work rolls, and was coated with Ni-P+SiC dispersion plating with a thickness of 108 layers. The finished surface roughness was adjusted to Ra of 0.3B. The plating bath contains 830g/Q of 60% nickel sulfamate solution and nickel chloride ISg/Q.
, boric acid 45g/Q, saccharin soda 3gIQ
, Composite plating is performed using a mixed solution of 150 g/Q of SiC (average particle size 5 μ-) while preventing agglomeration of solid particles by gas agitation with an inert gas.

The temperature of the plating bath was 57° C., p)I was 4.0, and the current density was 20 A/d+s3.

The friction coefficient of the composite plated test piece was measured using an abrasion tester as shown in FIG. The results of the friction coefficient are shown in Figure 3. It was confirmed that the friction coefficient was smaller than that of conventional cold-rolled work roll material, and it was found that the material had excellent lubrication properties.

Example 2 Composite plating similar to Example 1 was used for testing 4 former cold rolled 41
1 (work roll diameter φ165mm + barrel length 400mm
mm + backup roll: diameter φ480mm * barrel length 400mm) was applied to a work roll, and a stainless steel plate (SO3304, plate thickness 3.4mm) was rolled using 3z emulsion at a rolling reduction rate of 45z and a rolling speed of 1200s/
When the product was rolled with a sine mill, no heat streaks were observed, and the surface quality of the product was good.

[Effect of the invention] The surface of the work roll according to the present invention has Ni, N
i-P, Cu, hard Cr, Fe, Co and Ni-Co
as a matrix, with a Vickers hardness of 90
The work roll is coated with composite plating in which one or two or more types of solid fine particles of 0 or more are dispersed, and the work roll is cold-rolled while being sprayed with neat oil or an emulsion of oil dispersed in water. By reducing the coefficient of friction between the steel plate and the steel plate, it not only enables high-speed rolling without deteriorating the surface quality of the product, but also extends the life of the work roll due to improved wear resistance.

[Brief explanation of the drawing]

Figure 1: Schematic cross-sectional view of the surface of a work roll with composite plating, Figure 2: Abrasion tester. Figure 3: Relationship between friction coefficient and number of transfers.

Claims (1)

[Claims] 1. On the surface of the work roll, Ni, Ni-P, Cu, hard Cr, Fe, Co, and Ni-Co are used as a matrix, and one type of solid fine particles having a Vickers hardness of 900 or more is contained therein. Alternatively, a method for cold rolling a steel plate, which is coated with a composite plating containing two or more types of dispersed materials, and cold-rolled using the work roll while spraying neat oil or an emulsion of oil dispersed in water. 2. The method for cold rolling a steel sheet according to claim 1, wherein the neat oil sprayed onto the work roll or the oil used for the emulsion is mineral oil, natural oil, synthetic ester, or a mixture of two or more thereof. 3. Claim 1 or 2, wherein the steel plate to be cold rolled is an ordinary steel plate, a stainless steel plate, or a silicon steel plate.
A method of cold rolling the steel sheet described.