JPH02197302A - Oil for warm rolling and method for rolling using the oil - Google Patents

Abstract

PURPOSE:To manufacture a clad steel having no flaw by using a lubricating oil made by adding a specific amount of alkyl or allyldiurea whose molecular weight is a specific value to triester or tetraester of neopentylpolyol and fatty acid. CONSTITUTION:A triester or a tetraester of neopentylpolyol and fatty acid is used as a base oil and a semi-solid warm rolling oil made by adding 5-20wt.% of alkyl or allyldiurea whose molecular weight is 350-800 to the base oil is used. A rolled stock for which stainless steel and aluminum are superposed to each other is heated at a temp. of >=300 deg.C and is rolled by combination of a backup roll and a work roll adjusted so that roughness of respective rolls meets requirements by the inequalities I and a composite roughness meets requirements by the equation II. In the inequalities I and equation II, R shows composite roughness, Rs shows roughness of backup roll, RW shows roughness of work roll, and unit is mum Rrms. A clad steel having good surface brightness is manufactured with generation of no slip or seizing flaw.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a warm rolling oil and a rolling method using the same;
In particular, the present invention relates to a warm rolling oil used in forming clad steel of stainless steel and a low melting point non-ferrous metal, and a rolling method using the same.

(Prior Art) Generally, stainless steel is required to have excellent surface gloss. Excellent surface gloss is achieved by not creating oil puddles (oil bits) on the surface, and by not creating seizure or slip defects.

Oil bits are generated when a large amount of rolling oil is introduced between the rolls and the rolled material, and can be reduced by lowering the viscosity of the rolling oil and rolling at a low speed.

Seizing defects occur when high blood pressure occurs locally or when the oil film breaks due to frictional heat generation.
To prevent this, it is generally effective to 1) use a high viscosity oil, 2) increase the oil film strength, 2) reduce the rolling speed to suppress frictional heat generation, and 2) lower the rolling reduction ratio.

However, since the surface of stainless steel is covered with a stable passive film, it is difficult for lubricating oil to adsorb or react with it, and therefore it cannot be expected to increase the strength of the oil film.

Therefore, rolling of stainless steel sheets is carried out at low speed and under light pressure using low-viscosity rolling oil made by adding a small amount of alcohol or synthetic ester to mineral oil.

On the other hand, in recent years, multifunctional materials such as clad steel have been developed by bonding low melting point non-ferrous metals such as aluminum and copper with good thermal conductivity to stainless steel, and the demand for this material has increased. These clad steel plates are also required to have excellent surface gloss like conventional stainless steel plates.

(Problems to be Solved by the Invention) However, since it is difficult to form a clad under pressure unless the temperature is a certain degree, rolling is performed warmly (the temperature of the material to be rolled is usually 300 to 500°C).

Therefore, with conventional low-viscosity rolling oil, oil film breaks and seize defects occur. Therefore, if a high viscosity lubricating oil is used as a countermeasure against this problem, slip between the rolls will occur between the work roll and the backup roll which are in cold contact, and slip flaws on the roll will be transferred to the rolled material. It is also possible to use a lubricant containing a solid lubricant (for example, JP-A-62-197493 and JP-A-62-156199), but in this case, particles of the solid lubricant are pushed into the surface of the rolled material. Indentation flaws may occur during rolling, and solid powder may not be removed in the cleaning process after rolling, making it impossible to easily obtain a steel plate with excellent gloss.

Furthermore, the gloss of a steel sheet also changes depending on the surface roughness of the roll used. In order to obtain a steel plate surface with excellent gloss, it is advantageous that the surface roughness of the roll is small. However, if the surface roughness is small, the friction between the roll and the rolled material or between the work roll and the backup roll will be reduced, causing slip, which not only makes stable rolling impossible but also reduces the surface gloss due to slip flaws. descend. On the other hand, if the surface roughness of the roll is increased to prevent slipping, the gloss after rolling will be reduced.

As explained above, in order to obtain excellent surface gloss, it is necessary to prevent seizure when reducing the thickness of the oil film and prevent slip between rolls when using rolls with small surface roughness. It won't happen. However, in order to prevent seizure, it is necessary to make the oil film thick to some extent, and if it becomes too thick, slip between the rolls will occur. Furthermore, increasing the surface roughness of the rolls and thinning the oil film are effective ways to prevent slip between the rolls, but in this case, the surface gloss decreases and the oil film is more likely to run out, resulting in burnout. Attachment occurs.

Thus, it is necessary to develop a technology that simultaneously satisfies these contradictory properties.

In particular, the rolling process to form clad steel, which overlaps stainless steel and low-melting-point non-ferrous metals, is done at a warm temperature.
The lubrication conditions are more severe than in conventional cold rolling, and it is extremely difficult to develop a technology that simultaneously satisfies the contradictory properties of slip and seizure.

The present invention has been made to solve the conventional problem, and is used in warm rolling in which stainless steel and low-melting point nonferrous metals, particularly stainless steel and aluminum or copper, are overlapped and crimped. It is an object of the present invention to provide a warm rolling oil and a rolling method that make it possible to produce clad steel with excellent gloss without generating slip flaws or seizure flaws.

(Means for Solving the Problem) In order to achieve the above object, the present inventor has conducted various studies based on the following ideas.

(1) To prevent seizure that occurs due to lack of oil film due to temperature rise, ■Use a lubricating oil with excellent heat resistance that does not easily cause thermal decomposition at high temperatures as a base oil, ■Add a solid lubricant, ■Solid lubrication The particle size of the solid lubricant is made fine so as to uniformly supply the lubricant to the friction surface and prevent indentation flaws.

(2) In order to prevent slip between rolls and increase gloss, the surface roughness of the work roll and the backup roll is arranged in terms of their combined roughness to create an optimal combination.

As a result, in the present invention, a triester or tetraester of neopentyl polyol and a fatty acid is used as a base oil, and 5 to 20 wt% of alkyl or aryl diurea having a molecular weight of 350 to 800 is added to the semisolid cladding. A warm rolling oil for steel warm forming is formed, and further, in warm rolling where the temperature of the rolled material is 300°C or higher, each roughness satisfies the condition of formula (1) and the composite roughness satisfies the formula ( Warm rolling is performed by using a combination of a backup roll and a work roll adjusted to satisfy 2) and supplying the rolling oil.

0.5≦R<1.5, R11≧Rw −m−(+)
R=p positive W''---(2) where R is the composite roughness (μm Rrms), R8 is the roughness of the backup roll (μm Rrms),
Rw represents the roughness (μm Rrms) of the work roll.

(Function) The rolling oil of the first invention uses a fatty acid ester of neopentyl polyol as a base oil.

Neopentyl polyols include niopentyl glycol, trimethylolpropane, trimethylolethane, trimethylolbutane, trimethylolhexane, and pentaerythritol, and these compounds commonly contain pentane, which does not have hydrogen at the a-position in the molecular structure. Because it has a skeleton, it has the ability to resist thermal decomposition. Therefore, esters and tetraesters of pentaerytol, trimethylolethane, trimethylolbutane, trimethylolhexane, and trimethylolpropane with fatty acids have large molecular weights and are excellent in thermal stability. Chemistry” May 1, 1970, published by Saiwai Shobo,
It is described in known documents such as.

The feature of the present invention is that, in order to effectively utilize this known property, 5 to 20 wt % of a diurea compound having a molecular weight of 350 to 800, which will be described below, is added to dramatically improve the seizure resistance. A diurea compound is a compound having two urea bonds [-Nll-Co-NH-] in the molecule, and includes alkyldiurea, aryldiurea, alkylaryldiurea, etc. represented by the following general formula.

Alkyldiurea: R+-NHCONH-1t-N
HCONII-Ra aryldiurea: gu==>-N
HCON H-R-N iI CON II -(=
=) full * to 7'J- to 'i') and 7: 〈==)-
NIIICONR-R-IJHCONH-RrIn the formula, R
represents an incyanate group, and R1 and R3 represent an alkyl group (preferably an alkyl group having 4 to 18 carbon atoms).

In the above general formula, the phenyl group may be another aryl group such as naphthyl or substituted phenyl, and the alkyl groups of R1 and R2 may be cycloalkyl groups.

The reason why the molecular weight of the diurea compound is limited to 350 to 8 oo is because if it is less than 350, the seizure resistance will not improve dramatically, and if it exceeds 800, it will cause slippage and reduce gloss.

In addition, the reason why we limited the base oil to which these diurea compounds are added is fatty acid ester of neopentyl polyol is that even if they are added to other base oils, such as mineral oil, natural fats and oils, or synthetic esters, the seizure resistance will not improve. Unfortunately, it is so small that no dramatic improvement can be seen.

It should be noted that if the particle size of these diurea compounds exceeds 2 μm, it is not preferable because not only will the diurea compound not be uniformly dispersed in the rolling oil, but also it will be pushed into the surface of the material during rolling, creating dents and reducing gloss.

A more preferable particle size is 1.0 μm or less.

Furthermore, it is preferable that the amount of the diurea compound added is less than 5 to 20 vt%, and that the consistency of the rolling oil after addition is 150 to 350 at 25°C. This is because the dramatic improvement in seizure resistance due to the synergistic effect with neopentyl polyol fatty acid ester (base oil) will not be recognized, and the
This is because if it exceeds vt%, the consistency becomes too high and the lubricating film becomes thick, causing slippage between the rolls and lubricant pooling on the rolled material, resulting in a decrease in gloss.

The second invention relates to a rolling method for effectively demonstrating the performance of the rolling oil of the first invention. Excellent gloss can be obtained by rolling with a combination in which the combined roughness of the surface roughness of the backup roll and the surface roughness of the work roll is in the range of 0.5 to 1.5 μm, and the backup roll is rougher than the work roll. The object of the present invention is achieved without any slippage and the excellent seizure resistance of the rolling oil. The composite roughness of the backup roll surface roughness and the work roll surface roughness is 0.57.
If it is less than 1 m, slipping will occur, and if it exceeds 1.5 μm, the gloss of the rolled material after rolling will be reduced, or the oil film will tend to break partially, leading to seizure. Furthermore, if the work roll is rougher than the backup roll, the gloss of the rolled material will be reduced, or the oil film will tend to run out partially, leading to seizure.

In addition, in the second invention of the present application, the temperature of the material to be rolled is set to 300
The reason why the temperature is set to be higher than 300°C is that the adhesion between the stainless steel and the low melting point metal is insufficient at temperatures below 300°C, and the desired clad steel cannot be formed.

In addition, the upper limit of the temperature of the rolled material is (although not particularly limited)
The temperature is desirably about 500° C. because it is below the melting point of the low-melting point metal and the higher the temperature, the more an oxide film is formed on the surface of the material to be rolled, resulting in lower adhesion and surface gloss during molding.

As described above, in order to achieve the object of the present invention, it is more preferable to use the rolling oil of the first invention in the rolling method of the second invention.

(Example) Next, the present invention will be explained in more detail with reference to Examples.

The present invention was evaluated by preparing various rolling oils according to the present invention and conducting comparative experiments with these, conventional rolling oils, and comparative examples not included in the present invention.

Experiment 1 In order to compare the occurrence of seizure on friction surfaces when using the rolling oil of the present invention with that when using conventional rolling oil, a friction test was conducted using a Bowden friction tester.

The following examples were prepared as rolling oils of the present invention as samples to be used in experiments. Further, as conventional rolling oils for comparison, those shown in Table 1 were used.

Example 1 Pentaerythritol tetradecyl is used as a base oil, and this has a molecular weight of 400-500 and a particle size of 0.6-1.
Example 1 was prepared by adding and mixing 10 wt % of 2 μm alkyl diurea.

Comparative Example 1 Beef tallow is used as a base oil, and 1 alkyl diurea having a molecular weight of 350 to 400 and a particle size of 0.5 to 1.0 μm is added to this.
A rolling oil of Comparative Example 1 was prepared by adding and mixing 0 wt%.

Examples 2 to 4 Trimethylolpropane trioleyl is used as a base oil, and a compound having a molecular weight of 400 to 500 and a particle size of 0.6 to 1
．． 5vt% and 10vt of 2μm alkyldiurea, respectively.
% and 20vt% were added and mixed to create Examples 2 to 4.

Comparative Example 2 Furthermore, trimethylolpropane trioleyl was used as a base oil, and a base oil having a molecular weight of 400 to 500 and a particle size of 0.
Comparative Example 2 was prepared by adding and mixing 2vt% of alkyl diurea having a diameter of 6 to 1.2 μm.

Comparative Example 3 Similarly, trimethylolpropane trioleyl was used as the base oil, and the molecular weight was 250 to 300 and the particle size was 0.
Comparative Example 3 was also prepared by adding and mixing 10 vt% of alkyl diurea having a diameter of 5 to 1.0 μm.

Test conditions The test conditions were as follows, and 10 reciprocating sliding movements were performed.

Indenter shape: 3/1647 inch ball (Surface roughness: max
(O, 2μm or less) Indenter material: 5UJ-2 (quenched-tempered material) Flat plate dimensions: Thickness Q, 5ffim x width 1511 m
X length 100" (Surface roughness: Bmax0.5.gm) Flat plate material: SUS 43G-2B Sliding width: 10 mm Sliding speed 24"/1. .

Pressing load: 3 kgl Test temperature + 100.125.150.175.200
．． Table 1 shows the results of the temperature tests at 225, 250, 275 and 300°C.

As is clear from the table, seizure resistance is maintained up to 200'0 in all conventional rolling oils to which no diurea compound is added, and seizure is significant when the temperature exceeds 200°C.

On the other hand, in the rolling oil according to the present invention in which a diurea compound is added to a fatty acid ester of neopentyl polyol such as pentaerythritol or trimethylolpropane, seizure does not occur even at 250°C. In particular, the molecular weight is 3
When 5 to 20 wt% of a diurea compound of 50 or more is added, a dramatic improvement in seizure resistance is observed.

Experiment■ Next, a rolling experiment was conducted using a four-high rolling mill under the following conditions for the above examples and comparative examples, and the occurrence of slip between the rolls during rolling, the gloss of the material surface after rolling, and the presence or absence of seizure defects were investigated. It was observed and evaluated for slip resistance, seizure resistance, and gloss.

The following rolling oil was used as a sample for the experiment.

Example 5 Trimethylolpropane coconut oil fatty acid trinistyl was used as the base oil, and the molecular weight was 350 to 400 and the particle size was 0.
A rolling oil of the present invention was prepared by adding and mixing 5 vj% of alkyl diurea having a diameter of 5 to 1.0 μm.

Example 6 Similarly, trimethylolpropane coconut oil fatty acid triester was used as the base oil, and 10 wt% of alkyldiurea with a molecular weight of 400 to 500 and a particle size of 0.6 to 1.2 μm was added.
A rolling oil of the present invention was prepared by adding and mixing the above ingredients.

Example 7 Similarly, trimethylolpropane coconut oil fatty acid triester was used as the base oil, and 20vt% of alkyldiurea with a molecular weight of 600 to 650 and a particle size of 0.5 to 1.0 μm was added.
A rolling oil of Example 10 of the present invention was also prepared by adding and mixing.

Comparative Example 4 Mineral oil (30 csL/40°C) and Eurel stearate 3
A lubricating oil consisting of 0W [%].

Comparative Example 5 A lubricating oil consisting only of trimethylolpropane coconut oil fatty acid triester.

Comparative Example 6 Trimethylolpropane coconut oil fatty acid triester was used as the base oil, the molecular weight was 350 to 400, and the particle size was 0.
A rolling oil was prepared in which 2vt% of alkyl diurea of 5 to 1.02 m was added and mixed.

Comparative Example 7 Trimethylolpropane coconut oil fatty acid triester was used as the base oil, the molecular weight was 600 to 650, and the particle size was 0.
A rolling oil was prepared in which 25 wt % of alkyl diurea of 5 to 1.0 Jm was added and mixed.

Comparative Example 8 Trimethylolpropane coconut oil fatty acid triester was used as the base oil, the molecular weight was 850 to 1000, and the particle size was 0.
．． 5-1. A rolling oil was prepared by adding and mixing 15vt% of oJm alkyl diurea.

Comparative Example 9 Trimethylolpropane coconut oil fatty acid triester was used as the base oil, the molecular weight was 400 to 500, and the particle size was 2.
5-5 μm alkyl daurea T-15vt Rolling test conditions Work roll diameter: 100Φ Work roll surface roughness: RrIms 0.3 μm Backup roll diameter = 35oΦ Backup roll surface roughness: Rrms 1. O.J.
m Rolled material: ■SUS 430 thickness 9, 5 111" x width 300
ffllIX length 200m■ Aluminum lath A 111
24 Thickness 2. Q11Tl+y width 300” x length 20
011 Rolled material temperature: 350-400°C (inlet temperature) Reduction rate: 28% Thickness of the plate after making it into 05yF material. Rolling speed: 20 m/min Rolling oil supply: The rolling oil shown in Table 2 was supplied as a 10% emulsion from the exit side to the workpiece hole. The results of the rolling test are shown in Table 2. It was measured using a gloss meter, and a gloss of 600 or higher is rated as ○ (
Good), 500 to 599 was shown as Δ, and less than 500 was shown as × (poor).

As is clear from Table 2, the rolling oil of the present invention does not cause slip or seizure and has good gloss, and is superior to conventional rolling oils (Comparative Examples 4 and 5) and the range of the present invention. It can be seen that the rolling oil exhibits better performance than the rolling oils that come off (Comparative Examples 6 to 9).

For example, if the amount of diurea compound added exceeds 20 wt%, slipping occurs and gloss decreases (comparison between Example 7 and Comparative Example 7). In addition, the molecular weight of the diurea compound is 8
If it exceeds 00, slips are likely to occur. Furthermore, it can be seen that when the particle size exceeds 2 μm, the glossiness deteriorates.

Experiment ■ A rolling experiment was conducted under the same conditions as Experiment ■, but with the surface roughness of the work roll and backup roll combined as shown in Table 3.

Examples 8 to II below were prepared as samples contributing to the experiment, and used in combination with the surface roughness of the work roll and backup roll as shown in Table 3. Also,
These rolling oil supplies were supplied as 10% emulsions.

Example 8 Trimethylolpropanetrioyrel is used as a base oil, the molecular weight is 450 to 550, and the particle size is 0.3 to 0.8.
The rolling oil of the present invention was prepared by adding and mixing 12 wt % of alkylaryldiurea, which is .mu.m.

Example 9 Trimethylolbutanetriisostearyl oil, with a molecular weight of 500 to 600 and a particle size of 0.8 to 1.2
The rolling oil of the present invention was prepared by adding and mixing 1 ov 1% of alkylaryldiurea, which is .mu.m.

Example 10 Trimethylolhexanetridecyl is used as the base oil, the molecular weight is 650 to 700, and the particle size is 0.8 to 1.5μ
The rolling oil of the present invention was prepared by adding and mixing 15W% of alkylaryldiurea.

Example 11 Pentaerythritol tetraoctyl is used as the base oil, the molecular weight is 450 to 550, and the particle size is 0.3 to 0.8.
The rolling oil of the present invention was prepared by adding and mixing 8WL% of alkylaryl diurea having a diameter of 100 μm.

The experimental results are shown in Table 3.

Nos. 1 to 6 are combinations of roll roughness within the range of the present invention, and all have no slip or burn-in and are excellent in gloss.

On the other hand, Nos. 7 to 11 are combinations that are outside the scope of the present invention, and are considerably inferior in either slip resistance, burn resistance, or gloss. For example, for N11.7, the composite roughness is less than RrmsO15 μm, which is the lower limit of the roughness range of the present invention, and slipping occurs. Also, No, Il
And No. 9 has a synthetic roughness exceeding Rrms 1.5 μm, which is the upper limit of the roughness range of the present invention, and has poor seizure resistance and gloss. Furthermore, No. IO and No. 11 are cases where the roughness of the work roll is greater than the roughness of the backup roll, and the gloss and slip resistance are poor.

From the above experimental results, it was found that fatty acid triester or tetraester of neopentyl polyol was used as the base oil, and a diurea compound with a molecular weight of 350 to 800 was added at 5 to 20 W (%
It is clear that by adding it, the seizure resistance is dramatically improved and the slip resistance and gloss are excellent.

Furthermore, using such rolling oil, the composite roughness of the work roll and backup roll was adjusted to Rrms O, 5 to 1°5.
It can be seen that by setting the roughness in the μm range and making the roughness of the work roll finer than that of the backup roll, it is possible to produce clad steel with excellent gloss without causing seizure or slip.

(Effects of the Invention) As described above, in the wood WR invention, a triester or tetraester of neopentyl polyol and fatty acid is used as a base oil, and 5 to 50% of alkyl or aryl diurea having a molecular weight of 350 to 800 are added to the base oil. Adding 20vt% to form a semi-solid warm rolling oil for clad temperature-controlled opening molding,
Furthermore, in warm rolling where the temperature of the material to be rolled is 300°C or higher, a backup roll and a work roll are adjusted so that each roughness satisfies the condition of formula (1) and the combined roughness satisfies formula (2). Since warm rolling is performed by using a roll formed by combining the above and supplying the rolling oil, O, S≦R≦1.5. R121w ---(+)R
= f; dw'' --- (In the D formula, R is the composite roughness (Jlm Rrms), RB is the roughness of the backup roll (μm Rrms),
RW refers to the roughness of work rolls (μm Rrms), the combination of stainless steel and low melting point non-ferrous metals, and especially in warm rolling where stainless steel and aluminum are overlapped and crimped, clad steel with excellent surface gloss is used. It can be manufactured without generating slip flaws or seizure flaws.

71

Claims (1)

[Claims] 1. Triester or tetraester of neopentyl polyol and fatty acid is used as a base oil, and this has a molecular weight of 350.
~800 alkyl or aryl diurea from 5 to 20w
Warm rolling oil for warm forming of semi-solid clad steel with t% added. 2. Backup rolls and work rolls adjusted so that the roughness of each material satisfies the conditions of formula (1) and the combined roughness satisfies formula (2) during warm rolling where the temperature of the rolled material is 300°C or higher. using a roll consisting of a combination of
A rolling method in which rolling oil according to the claims is supplied and the rolling process is carried out. 0.5≦R≦1.5, R_B≧R_W---(1) R=
√(R_B^2+R_W^2)---(2) In the formula, R is the composite roughness (μmRrms), R_B is the roughness of the backup roll (μmRrms),
R_W represents the roughness (μmRrms) of the work roll.