JPH06210326A - Cold-rolling roll and cold rolling method - Google Patents

Abstract

PURPOSE:To decrease the wear quantity of a roll by making chrome plating performed on the surface of a roll trivalent chrome plating or composite platings obtained by dispersing one out of SiC, etc., and diamonds in the matrix by making trivalent chrome plating a matrix. CONSTITUTION:The cold-rolling roll is obtained by performing chrome plating on the surface of a roll. The chrome plating is trivalent chrome plating or composite platings obtained by dispersing at least one out of SiC, ZrB2, Si3N4, Al2O3, Cr3C2, B4C, CBN and diamonds in the matrix by making trivalent chrome plating a matrix. And the cold rolling method is characterized by cold rolling while supplying emulsion lubricating oil or soluble lubricating oil obtained by dispersing oil in neat oil and water with a rolling roll, to a roll bite. Consequently, the wear quantity of a roll is decreased, a lubrication effect is improved, the life of the roll is extended, and a productivity is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cold rolling roll and a method of cold rolling using the rolling roll.

[0002]

2. Description of the Related Art One of the properties required of rolling rolls is wear resistance. Conventionally, the hardness of the roll material has been increased by adding Cr or quenching to improve the wear resistance. In addition, recently, in order to improve wear resistance, chrome plating is also performed on the roll surface (for example,
See Materials and Processes 3 (1990), 1350 and Materials and Processes 5 (1992), 511).

[0003]

The conventional chromium plating applied to the roll surface is hexavalent chromium plating. The hexavalent chromium plating is characterized in that its hardness decreases as the temperature rises. On the other hand, during cold rolling, the temperature inside the roll bite rises to, for example, about 300 ° C. due to the deformation heat of the rolled material and the friction heat between the roll and the roll. As a result,
The hexavalent chromium plating has a problem that the hardness is lowered and the wear resistance is reduced.

The present invention is intended to provide a cold rolling roll having excellent wear resistance. Further, the present invention intends to provide a cold rolling method capable of improving lubricity by using the above cold rolling roll.

[0005]

In the cold rolling roll of the present invention, the roll surface is plated with chrome. The chromium plating is trivalent chromium plating or trivalent chromium is used as a matrix in which SiC, ZrB ₂ ,
Si ₃ N ₄ , Al ₂ O ₃ , Cr ₃ C ₂ , B ₄ C, CB
It is a composite plating in which at least one of N and diamond is dispersed.

Forged steel, chrome steel or the like is used as the roll base material. If the plating thickness is less than 1 μm, the wear of the plating is fast, and if it exceeds 50 μm, the plating is easily peeled off. Further, if the average particle size of the dispersant is too small, abrasion resistance cannot be obtained, and if it is too large, the plating tends to peel off. Therefore, the average particle size of the dispersant is preferably about 0.1 to 20 μm. Further, if the amount of eutectoid is too small, there is no abrasion resistance, and if it is too large, the plating is likely to peel off. Therefore, the amount of eutectoid is preferably about 0.1 to 20 wt%. There are an electrolytic method and an electroless method as the plating method, but the electrolytic method is preferable in consideration of the efficiency of the plating operation and the efficient co-deposition of the dispersant. Further, in order to uniformly disperse the dispersant in the plating bath, a chemical method using a surfactant or a physical method using air stirring is used.

The cold rolling method of the present invention uses the cold rolling rolls described above to cold roll while supplying neat oil, emulsion lubricating oil in which oil is dispersed in water, or soluble lubricating oil to a roll bite. To do.

The oil used as the lubricating oil may be any of mineral oil, natural oil and fat, synthetic ester, and a mixture of two or more kinds thereof. Paraffinic mineral oil
Examples of the naphthene-based and natural oils and fats include beef tallow, palm oil, rapeseed oil and lard, and synthetic esters include butyl stearate, octyl stearate, coconut oil and trimethylol propane fatty acid.

[0009]

OPERATION FIG. 1 shows the change in average surface hardness with temperature as 3
Valence chromium plating and hexavalent chromium plating are shown in comparison. Work roll temperature in the roll bite during cold rolling 2
It can be seen that the hardness corresponding to 00 to 300 ° C. is significantly higher in the trivalent chromium plating than in the hexavalent chromium plating. The amount of roll wear decreases as the average surface hardness increases.

FIG. 2 shows changes in the amount of roll wear depending on the average surface hardness in comparison with trivalent chromium dispersed plating, hexavalent chromium plating and forged steel. The average particle hardness is increased by the hard particles of the dispersant dispersed in the plating matrix, and the wear amount is reduced almost linearly. FIG. 3 shows the relationship between the amount of SiC eutectoid and the amount of roll wear. The amount of roll wear gradually decreases as the amount of eutectoid SiC increases.

FIG. 4 shows the relationship between the amount of SiC eutectoid and the friction coefficient between the rolled material and the roll. The friction coefficient gradually decreases as the amount of eutectoid SiC increases.

In the case of composite plating, some hard particles of the dispersant are projected from the plating matrix surface. When the work roll bites the rolled material, most of the hard particles are in contact with the rolled material, and numerous minute voids are formed between the plating matrix surface and the rolled material surface. Lubricating oil collects in the voids to enhance the lubricating effect.

[0013]

Example A plain steel plate (plate thickness: 1.1 mm, plate width: 250 mm, length: 3 Km) was cold-rolled using the following work rolls. Roll size Diameter: 165 mm Width: 400 mm Roll base material C: 1% Cr: 3% Si:
0.6% S: 0.4% Mo: 0.3% Fe: Residual plating Matrix: Trivalent chromium Plating thickness: 10-30 μm Dispersed particles: SiC Average particle size: 3 μm Eutectoid amount: 4 wt% Surface hardness Hv1200 surface roughness 0.29 μm Ra The rolling speed was about 80 m / min, and the rolling reduction was 20 to 30%. Further, a beef tallow rolling lubricant was used as the lubricant.

As a result of rolling under the above conditions, the amount of roll wear was about 3 μm.

As a comparative example, cold rolling was performed by using a forged steel roll (same size, no plating, surface roughness: 0.31 μm Ra) under the same rolling conditions as above. As a result, the amount of roll wear was 6 to 8 μm, which was about twice as much as that of the present invention.

[0016]

In the cold rolling roll of the present invention, the surface average hardness increases as the roll temperature rises during cold rolling, which reduces the amount of roll wear.

Further, in the cold rolling method of the present invention, the lubricating oil is accumulated in the minute gaps between the plating matrix surface and the surface of the rolled material, and the lubricating effect is enhanced.

From the above, according to the present invention, the roll life can be extended, the productivity can be improved, and the manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 is a diagram showing a change in average surface hardness with temperature in comparison between trivalent chromium plating and hexavalent chromium plating.

FIG. 2 shows the change in roll wear amount due to the average surface hardness of 3
FIG. 3 is a diagram showing a comparison between valent chromium dispersed plating, hexavalent chrome plating, and forged steel.

FIG. 3 is a diagram showing the relationship between the amount of SiC eutectoid and the amount of roll wear.

FIG. 4 is a diagram showing the relationship between the amount of SiC eutectoid and the coefficient of friction between rolled material and rolls.

Front Page Continuation (72) Inventor Fuyasu Yamamoto 20-1 Shintomi, Futtsu City, Chiba Shin Nippon Steel Co., Ltd. Technology Development Division (72) Inventor Matsuo Ataka 20-1 Shintomi, Futtsu City, Chiba Shin Nippon Steel Stock Company Technical Development Headquarters (72) Inventor Kouhei Nakajima 20-1 Shintomi, Futtsu City, Chiba Prefecture Nippon Steel Co., Ltd. Corporate Technology Development Headquarters (72) Inventor Issei Terayama 2 Akasaka Coast, Kokurakita-ku, Kitakyushu, Fukuoka -1 Ishikawa Metal Industry Co., Ltd. (72) Inventor Mitsutoshi Fujimura 495-143, Niijima, Wakamatsu Ward, Kitakyushu City, Fukuoka Prefecture Fujimura Industry Co., Ltd.

Claims (2)

[Claims] 1. A cold rolling roll having a chromium surface plated with chromium, wherein the chromium plating comprises trivalent chromium plating or trivalent chromium as a matrix in which S is added.
iC, ZrB ₂ , Si ₃ N ₄ , Al ₂ O ₃ , Cr
A cold rolling roll which is a composite plating in which at least one of ₃ C ₂ , B ₄ C, CBN and diamond is dispersed. 2. The cold-rolling roll according to claim 1, wherein neat oil, emulsion lubricating oil in which oil is dispersed in water, or soluble lubricating oil is cold-rolled while being supplied to a roll bite. Cold rolling method.