JPH0436196B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a cold rolling oil for steel plates that is used when performing high-speed rolling at a high reduction rate in cold rolling of steel plates. (Prior art) Cold rolling oil is supplied in the form of an emulsion between the work roll and the material to be rolled (hereinafter referred to as roll bite) when cold rolling a steel plate, reducing the coefficient of friction and improving the rolling process. It has the role of suppressing heat generation and load during. Base oils for rolling oils are broadly classified into three types: mineral oils, synthetic esters, and animal and vegetable oils represented by palm oil and beef tallow. Mineral oil base oils have poor oil film strength but excellent burn-off properties, and are used for materials with relatively thick finished thickness and low rolling reduction, and are used in so-called mills that omit the cleaning process after rolling. Suitable for clean processes. In addition, synthetic esters have excellent burn-off properties and a fairly strong oil film strength, so they are generally blended in appropriate amounts with mineral oils and used in the mill clean process. On the other hand, animal and vegetable oils have a strong oil film and are able to form a sufficient oil film on the roll bite and exhibit excellent lubrication performance even under conditions of high rolling load and high speed rolling, resulting in a high rolling reduction. , and is suitable for cold rolling thin products with a finished thickness of 0.4 mm or less that are rolled at high speeds. The reason why these animal and vegetable oils and fats have excellent oil film strength and lubricity is that the molecular weight of the base oil is large, and the viscosity is 50°C.
In addition to having a high value of 25 cst or more and having high adsorption properties, it also contains a certain amount of higher fatty acids. In recent years, continuous casting of rolled materials (cold-rolled products) has progressed, and more than 90% of them are Al-killed continuous casting materials. Along with this, in the rolling of thin steel sheets, especially tinplate sheets, the friction coefficient at roll bite is too low due to the smoothing wear phenomenon (roughness wear) of the work rolls and the excessively high lubrication performance of the rolling oil, resulting in instability. A slip phenomenon has started to occur. It is well known that the relationship between the friction coefficient, rolling reduction rate, and advancement rate during roll bite is as shown in the graph shown in FIG. That is, the lower the friction coefficient, the lower the advance rate. When the friction coefficient becomes 0.01, the advance rate becomes 0 when the reduction rate is about 35%, and slips begin to occur. The inventors also investigated the rolling force and tension values obtained during rolling of Al-killed continuous cast material (hereinafter referred to as CC material), ingot cast material (hereinafter referred to as IC material), and the rolled material at that time. When the change in friction coefficient is calculated from the deformation resistance value using KARMAN's differential equation, the graph shown in Figure 2 is obtained. From this, it is clear that the friction coefficient decreases faster when the rolled material is CC material than when it is IC material. The reason for this is not yet clear, but this phenomenon mainly appears in experiments conducted by the present inventors and in actual rolling using rolling oil made from animal and vegetable base oils.
It can be organized as follows. (1) A comparison of beef tallow (sample oil 1), which is a typical animal and vegetable oil base oil, and a low-viscosity ester (sample oil 2) using the ingredients, test equipment, and test conditions shown in Table 1 below shows that beef tallow It can be seen that the coefficient of friction is lower in the case of 200 mm, and the proportion of the fluid lubrication area on the friction surface is relatively high (see Figure 3).

[Table] ○Testing machine: Small two-high rolling mill WR100φ×130Lmm ○Test conditions: 3-pass rolling (total reduction target of 65%) Rolling speed 10mpm Test material spcc-
D1.65T×20.0W×200Lmm Emulsion density 5
%, temperature 60℃, flow rate 1.5l/min WR roughness Rz≒0.8μm (emery paper 120 polishing) (2) CC material has higher reactivity with higher fatty acids contained in base oil than IC material. (See Figure 4) It is easy to produce iron soap, which is a reaction product with high lubricity. (3) CC material has higher hardness than IC material. In short, the synergistic effect of the high viscosity of animal and vegetable fats and oils (more than 25cst at 50℃) and the high viscosity of iron soap, which is a reaction product of higher fatty acids, reduces the metal contact area on the friction surface and expands the fluid lubrication area. No major adhesive wear with enlarged roughness regeneration occurs. Therefore, only the protrusions at the tip of the polished surface of the roll are eliminated, and as a result, the smoothing wear phenomenon of the work roll surface is promoted, which is thought to lead to a faster decrease in the coefficient of friction for the CC material. . Due to the smoothing wear phenomenon of the work roll surface,
As mentioned above, it was found that unstable slips are likely to occur, and the tension fluctuations caused by this slips are triggered to cause chattering. Therefore, it is necessary to rearrange the work rolls to recover the friction coefficient. These phenomena not only reduce rolling efficiency but also have the drawback of causing abnormalities such as poor plate thickness and plate breakage. (Object of the Invention) The present invention has been made to eliminate these drawbacks, and has been made to reduce the occurrence of slips caused by wear of work rolls and chatter induced by this, and to improve roll wear resistance. The object of the present invention is to provide a cold rolling oil for steel plates that has a good and stable friction coefficient within the roll bite. (Structure of the Invention) In order to achieve the above object, the present invention uses a synthetic ester or a mixed oil with animal and vegetable oil as a base oil, and the viscosity of this base oil is 15cst or less at 50°C. 1 lower fatty acid with 6 to 10 carbon atoms to
The cold rolling oil for steel sheets is characterized in that ~10% is added, and the synthetic esters used as the base oil include stearic acid methyl ester, beef tallow fatty acid methyl ester, stearic acid octyl ester, beef tallow fatty acid octyl ester. , stearic acid butyl ester, stearic acid neobentyl glycol ester, coconut oil fatty acid neobentyl glycol ester, and the like. Beef tallow, palm fat, coconut oil, rapeseed oil, etc. may be added as animal and vegetable oils and fats, but it is essential that the viscosity of the mixture is 15 cst or less at 50°C.
When the viscosity exceeds 15 cst, as seen in the examples,
Roughness wear increases rapidly. The lower fatty acids to be added include caproic acid, enantylic acid, caprylic acid, pelargonic acid, and capric acid, and the amount added is 1 to 10%, preferably 2 to 7%. When the amount added is less than 1%, as shown in Table 3 below, the effect of preventing the formation of stearic acid, which is a higher fatty acid, and beef tallow fatty acid iron soap is not significant.
If it exceeds 10%, the preventive effect will be saturated and the added effect will not be obtained. (1) Test oil

[Table] (2) Test method Using a known rotational deterioration tester, the emulsion was subjected to rotational deterioration for the purpose of producing ironstone. From the emulsion after deterioration, ironstone is extracted by solvent fractionation, and after acid decomposition and methyl esterification, the fatty acid composition is determined by gas chromatography. (3) Deterioration test conditions Atmosphere: 80℃ air, rotation speed: 60rpm, sample oil: 5% emulsion, steel ball: 1/2 inch-100
Potato chips: 30g, rotation time: 56 hours ○ Test results (caprylic acid/stearic acid + beef tallow fatty acid) The state of deterioration is shown in Table 3.

[Table] (Function) As mentioned above, the smoothing wear phenomenon on the work roll surface is due to the synergistic effect of the high viscosity of the base oil and the viscosity of the iron soap produced by higher fatty acids, which expands the fluid lubrication area and improves roll polishing. This is caused by wear of the sharp protrusion of the surface, but the present invention improves the smoothing wear resistance from the following two aspects and aims at rolling with a stable wear coefficient in the roll bite. be. (1) By lowering the viscosity of the base oil, the boundary lubrication area is expanded, preventing tip wear and promoting roughness regeneration. (2) The addition of lower fatty acids having 6 to 10 carbon atoms prevents the formation of ironstone (which expands the fluid lubrication area) with the higher fatty acids contained. As a result, lower fatty acid iron soap is produced, but compared to higher fatty acid iron soap, this has poor oil solubility due to the shorter chain length of the alkyl group, and also has lower viscosity.
It easily falls out of the oil and has difficulty entering the friction surface. Therefore, iron soaps containing lower fatty acids having 6 to 10 carbon atoms are less harmful to the smoothing wear phenomenon. As mentioned above, the addition of lower fatty acids not only has the effect of preventing the formation of higher fatty acids, but also improves the adsorption performance, leading to enhanced boundary lubrication performance. Furthermore, lower fatty acids having 5 or less carbon atoms are not preferred because they become water-soluble as shown in Table 4 below, and their addition significantly lowers the pH of the emulsion and increases the rusting rate of the coil after rolling.

[Table]
Furthermore, as the viscosity of the base oil decreases, the boundary lubrication region expands and seizure becomes more likely to occur. (reacts to)
There is no denying that the boundary lubrication performance can be enhanced by adding solid lubricants or solid lubricants. Examples of the products of the present invention are shown below along with comparative examples. Example...Evaluation of roll friction resistance (1) Test oil

[Table] (2) Test method Testing machine Large Chimken testing machine Ring block ○Ring (assumed to be a rolling roll) 62mmφ×19mmW Material: SUJ2 (HV≒800) Roughness: Rz=1.8~2.2μm (C direction) ○Block ( Rolled material) Actual machine cold rolling material (CC material, degree of processing approx. 50%) Test conditions ○Ring speed 600rpm ○Load 45Kg (Hertzian pressure 18.2Kg/ ^cm2 ) ○Time 3 hours ○Emulsion concentration 5%, Temperature: 60℃ (3) Evaluation Measure the surface roughness (RzC direction) of the ring before and after the test, and judge based on the amount of decrease in roughness. The test results are shown in Figure 5. The product of the present invention shows less decrease in roughness of the ring surface due to friction with the CC material than the comparative example. (Effects of the Invention) As explained above, the cold rolling oil for steel plates of the present invention uses a synthetic ester or a mixed oil of this with animal and vegetable oil as a base oil, and lower fatty acids having 6 to 10 carbon atoms are added thereto. As a result, the work roll has excellent roughness and wear resistance when rolling CC materials, and slips and chattering can be prevented during cold rolling of thin steel sheets, which has the excellent effect of significantly improving productivity. be.

[Brief explanation of drawings]

Figure 1 is a graph showing the relationship between the friction coefficient and rolling reduction rate in steel sheet rolling and the advance rate during roll bite, Figure 2 is a graph showing the friction coefficient during rolling, and Figure 3 is a graph showing the relationship between beef tallow and low viscosity ester. FIG. 4 is a graph showing the coefficient of friction, FIG. 4 is a graph showing the reactivity of fatty acids, CC materials, and IC materials, and FIG. 5 is a graph showing the test results for products of the present invention and comparative examples.

Claims (1)

[Claims] 1 Synthetic ester or a mixed oil of this with animal and vegetable oils is used as the base oil, and the viscosity of this base oil is 50℃.
15 cst or less, and is characterized by adding 1 to 10% of a lower fatty acid having 6 to 10 carbon atoms.