JP2898824B2 - Manufacturing method of high gloss metal plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a metal sheet having an excellent surface gloss, and in particular, a roll cloth rolling method is employed in cold rolling to efficiently produce a metal sheet having a high gloss. It relates to a method of manufacturing.

[0002]

2. Description of the Related Art In recent years, for example, a stainless steel plate or the like has been increasingly used as it is in a cold rolling state, taking advantage of the beauty of the metal surface itself. In this case, good surface gloss of the metal plate is an important factor in determining commercial value.

In order to improve the surface gloss of a metal plate, a work roll having a small surface roughness is used during cold rolling.
In addition, it is necessary to perform rolling while reducing the amount of lubricating oil drawn into between the metal plate and the work roll (roll bite). If the amount of lubricating oil entering the roll bite is large, the surface of the metal plate is freely deformed during rolling due to the effect of the lubricating oil trapped on the interface between the roll and the metal plate, causing micro defects called oil pits and reducing gloss Let it.

Conversely, if lubrication is insufficient, the work roll and the metal plate come into direct contact, causing seizure. For this reason, conventionally, a method of rolling using neat oil as a lubricating oil has been adopted in order to suppress the amount of lubricating oil introduced with a small-diameter work roll and prevent seizure. At this time, if the roughness of the work roll is large, the surface roughness of the rolled product increases, and seizure also occurs, so the roughness of the work roll is defined as a center line average roughness (Ra) of 0.
Countermeasures have been taken such as reducing the thickness to 1 μm or less.

For example, Japanese Patent Publication No. 57-13362 proposes a method of devising work roll roughness using a small-diameter Sendzimir rolling mill. However, such a rolling method using a small-diameter roll has a problem that the rolling speed is small and the productivity is low. In addition, in order to properly maintain the surface roughness of the work roll, frequent work such as roll polishing and roll change is required, which increases the manufacturing cost.

[0006] On the other hand, it is difficult to obtain a high-gloss metal plate even if rolling is performed using a normal emulsion lubricating oil in a rolling mill using a large-diameter roll for the purpose of improving productivity. As described above, oil pits are generated if the amount of lubricating oil introduced into the roll bite during rolling is excessive, and seizure occurs if the amount is insufficient. The amount of lubricating oil introduced into the roll bite is governed by the viscosity of the lubricating oil and the particle size of the emulsion.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to use a large-diameter roll mill having a high rolling speed and high productivity.
In addition, it is an object of the present invention to provide a method for manufacturing a high gloss metal sheet without extremely reducing the roughness of a work roll.

[0008]

Means for Solving the Problems The present invention provides an emulsion base oil which uses a lubricating oil having a viscosity at 40 ° C. of 30 to 200 cSt and an average emulsion particle size of 10 μm or less, and in a plane parallel to the rolled material. A method of producing a metal sheet having excellent gloss, characterized in that rolling is performed while intersecting the upper and lower work rolls at an angle of at least 0.3 ° with respect to a line perpendicular to the rolling direction.

The above-mentioned intersection of the work rolls means that the upper and lower work rolls are each inclined at an angle of θ with respect to a direction perpendicular to the rolling direction in a plane parallel to the rolling surface as shown in FIG. That is. Such a rolling method is called roll cross rolling. On the other hand, the usual method of rolling the upper and lower work rolls in parallel is referred to herein as parallel roll rolling. In a rolling mill having a backup roll, the work roll roll is often inclined together with the backup roll. This is called pair cross rolling. The above θ is called an intersection angle (cross angle), and in the method of the present invention,
This θ is set to 0.3 ° or more.

[0010]

FIG. 1 is a view for explaining the principle of roll cross rolling. As shown in the drawing, when the upper and lower work rolls have a certain crossing angle (θ) in a plane parallel to the metal plate (plane parallel to the rolling surface), the metal plate has Vs with respect to the rotation speed Vr of the work roll. With speed. For this reason, a relative slip occurs between the work roll and the metal plate, and as a result, a shear stress Fc in the width direction of the plate (Fc ′ on the back surface of the metal plate) is generated.

Normally, the circumferential surface of the work roll is left with polishing marks in the circumferential direction when the work roll is polished, and peaks and valleys are formed. FIG. 2 (a) schematically shows such a contact state between the roll surface and the metal plate of the material to be rolled. The peaks are in contact with the metal plate, and the valleys are filled with lubricating oil.
In the case of parallel roll rolling (cross angle θ = 0 °), the peaks are always in contact with the surface of the metal plate during rolling, and in the valleys, the metal plate and the work roll are always separated by lubricating oil. ing. An oil pit is generated by the pressure of the lubricating oil. Therefore, in order to obtain a product with a low surface roughness and a high gloss, it is necessary to make the peak of the work roll as small as possible and to reduce the amount of lubricating oil.

FIG. 2 (b) shows the contact state between the roll surface and the metal plate surface during roll cross rolling. In this case, the surface of the plate is ground by sliding the crests of the roll in the width direction of the plate, thereby preventing a decrease in gloss at the valleys. In addition, seizure is prevented by the lubricating oil trapped in the valleys. That is, according to this method, a metal plate having a high glossiness can be obtained even under lubricating conditions in which oil pits are conventionally generated, and rolling can be performed without seizure even if the work roll has a certain surface roughness. Becomes

When the cross angle of the work roll for effectively exerting the above-mentioned effects was confirmed by an experiment, it was found that a cross angle of 0.3 ° or more was sufficient. If the cross angle is less than 0.3 °, the grinding effect due to slip cannot be sufficiently exerted. If the cross angle is too large, a problem occurs in that the rolled metal plate is twisted. In an actual operation, the upper limit of the cross angle is about 3 °.

Next, the lubricating oil will be described. Lubricating oils generally used for rolling include neat oils and emulsions,
When a high-gloss product is obtained with a small-diameter roll, neat oil is mainly used. On the other hand, an emulsion is considered to be effective in rolling by a normal large-diameter roll. However, in order to achieve both high gloss and high lubricity in rolling using an emulsion, the viscosity of the oil serving as the base oil of the emulsion, the concentration of the emulsion, the particle size of the emulsion, and the like are restricted.
In other words, there are many restrictions on emulsions that can be used as lubricating oils, and the range of choice is narrow.

Conventionally, as an emulsion for ordinary steel,
Base oil is a mixture of tallow or mineral oil and synthetic esters,
An emulsifier was added to the mixture and mixed with water.
However, ordinary parallel roll rolling using such an emulsion does not always provide a product with high gloss. To increase the gloss, a method of reducing the emulsion particle size or decreasing the viscosity is conceivable, but this causes seizure. Therefore, it is necessary to take measures to prevent seizure by increasing the compounding amount of the synthetic ester or adding an additive. That is, unless the conditions of the emulsion are carefully controlled and maintained, it is not possible to obtain a product with high glossiness without occurrence of seizure.

The present inventor conducted various experiments on the assumption that the lubricating oil that can be used would be changed by changing the rolling method to roll cross rolling. According to the results, the emulsion is more effective than the neat as the lubricating oil used for the roll cross rolling. Emulsions are suitable for high-speed rolling because of their higher cooling capacity than neats.

Next, lubricating oils having various emulsion base oil viscosities and emulsion particle diameters were prepared and subjected to experiments. It was found that the base oil viscosity at 40 ° C. was 30 cSt or more. Below this, some seizures were observed. on the other hand,
When the viscosity of the base oil at 40 ° C. exceeded 200 cSt, the lubrication became excessive, causing a decrease in gloss and some slippage.

The average particle size of the emulsion is as follows.
10 μm or less is desirable. If it exceeds 10 μm, excessive lubrication such as slip was observed in some parts. The lower limit of the emulsion average particle size is not particularly limited. However, in the current emulsion manufacturing equipment, the thickness is usually 2 μm or more.

[0019]

Embodiment 1 The effects of the present invention will be described based on embodiments.

The steel strip of ferritic stainless steel (SUS430-2B) pickled and annealed is subjected to the method of the present invention and the conventional method (θ =
0 parallel roll rolling). Table 1 shows rolling conditions and lubricating oil characteristics.

The comparison of the effects was made based on the surface gloss after rolling. Gloss was evaluated using a gloss meter specified in JIS-Z8741 and AA, 600 to 700
Was assigned A, and the following 150 ranks were used to give a five-level ranking.

Tables 2 to 4 collectively show the cross angle (θ) of the roll, the average particle size of the emulsion of the lubricating oil, the viscosity at 40 ° C., and the evaluation of the glossiness of the obtained plate.

From these tables, it can be seen that it is difficult to obtain a high gloss even by controlling the viscosity and particle size of the emulsion by the conventional parallel roll rolling method. That is, seizure easily occurs in the low-viscosity region, and problems such as slippage occur in the high-viscosity region.

In contrast, in the method of the present invention in which the cross angle of the roll is set to 0.3 ° or more and the viscosity of the lubricating oil and the emulsion particle size are properly selected, products having high glossiness are obtained in all cases.

[0025]

[Table 1]

[0026]

[Table 2]

[0027]

[Table 3]

[0028]

[Table 4]

[0029]

Example 2 Low-carbon steel (JIS G 3141) and austenitic stainless steel (JIS SUS 304) were cold-rolled by the method of the present invention. The rolling conditions are shown in Table 5, and the lubricating oil used is shown in Table 6.

The surface gloss of the obtained rolled product was evaluated in the same manner as in Example 1. Table 7 shows the results.

From Table 7, it is clear that the method of the present invention can be applied to the rolling of various metal sheets, and the types of lubricating oils that can be used are also various.

[0032]

[Table 5]

[0033]

[Table 6]

[0034]

[Table 7]

[0035]

According to the method of the present invention, it is possible to produce a metal plate having high productivity and excellent gloss using a large-diameter work roll.

[Brief description of the drawings]

FIG. 1 is a plan view of a work roll portion for explaining the principle of roll cross rolling.

FIG. 2A is a schematic view showing a contact state between a work roll and a metal plate during normal parallel roll rolling. (b)
FIG. 4 is a schematic diagram showing a slip state of a work roll surface convex portion during roll cross rolling.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toru Kaneko 4-53-3 Kitahama, Chuo-ku, Osaka-shi, Osaka Sumitomo Metal Industries, Ltd. (72) Inventor Kanji Hayashi 4--6 Kannonshinmachi, Nishi-ku, Hiroshima, Hiroshima, Japan No. 22 Mitsubishi Heavy Industries, Ltd.Hiroshima Plant (72) Inventor Tetsuo Kajiwara 4-22 Kannon Shinmachi, Nishi-ku, Hiroshima City, Hiroshima Pref. 4-6-22 Kannon Shinmachi, Hiroshima Research Laboratory, Mitsubishi Heavy Industries, Ltd. (56) References JP-A-4-71701 (JP, A) JP-A-4-118101 (JP, A) JP-A-3-172392 (JP) (A) JP-A-4-17908 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B21B 1/22 B21B 3/02 B21B 45/02

Claims (1)

(57) [Claims] An emulsion base oil having a viscosity at 40 ° C. of 30.
Use a lubricating oil with an emulsion average particle size of 10 μm or less at ~ 200 cSt, and intersect the upper and lower work rolls at an angle of 0.3 ° or more with a line perpendicular to the rolling direction in a plane parallel to the rolled material. A method for producing a metal plate having excellent gloss, wherein rolling is performed while the metal plate is rolled.