JPH0978080A - Lubricant composition for high-temperature working and its usage - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a nongraphitic lubricant composition for high-temperature working, having excellent lubricity without causing the carburizing or phosphorating and capable of preventing scratches from occurring due to a substrate. SOLUTION: This lubricant composition for high-temperature working is obtained by blending one or more particulate oxide-based layer materials selected from potassium tetrasilicic mica, sodium tetrasilicic mica, natural phlogopite, bentonite, montmorillonite and vermiculite with one or more binders selected from boron oxide, boric acid, an alkali metallic borate, sodium carbonate, potassium carbonate and sodium silicate or potassium silicate having <=100 deg.C melting point at (1:4) to (1:1) weight ratio of the particulate oxide-based layer materials to the binders. The lubricant composition for high-temperature working is used by dispersing and dissolving the composition in water at 20-80 weight ratio.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lubricant composition for high temperature processing, particularly a lubricant composition for high temperature processing which is suitable for use in seamless steel tube rolling by a mandrel mill and a method of using the same.

[0002]

2. Description of the Related Art Manufacture of seamless steel pipes by the Mannesmann-mandrel mill system is carried out by punching a round steel piece heated in a rotary hearth type heating furnace with a piercing and rolling machine to form a hollow shell, and then lubricating the outer surface. The mandrel bar coated with the agent is inserted into the hollow shell in a skewered shape, and is rolled to a predetermined size in one pass by a mandrel mill consisting of 7 to 9 stands. After this mandrel mill rolling, the pipe from which the mandrel bar was pulled out was cut with a hot saw after the portion with poor pipe end shape was cut.
It is reheated in a reheating furnace, its outer surface is descaled by high-pressure water, and subjected to an outer diameter reduction and a slight wall thickness reduction by a stretch reducer to form a tube of a predetermined size. Thereafter, the tubes are cooled on a cooling bed, cut to the required length by a cold saw and sent to a refining line.

In the manufacture of the seamless steel pipe by the Mannesmann-mandrel mill system, the mandrel bar is inserted into the hollow shell at 1100 to 1200 ° C. and is easily seized, but the lubrication applied to the outer surface thereof. The agent acts as a protective film to prevent seizure. In addition, the pipe shape and wall thickness after rolling the mandrel mill are affected by the roll rotation speed and roll hole type of the mandrel mill,
It is also affected by the friction between the mandrel bar and the material. However, if a lubricant having a small friction coefficient is used, uniform deformation is made in the circumferential direction and the axial direction, and a stable pipe shape and wall thickness distribution can be obtained. Further, the mandrel bar is pulled out from the pipe by a burst ripper after rolling, but if the lubricity is poor, the pipe and the mandrel bar will be seized and the bar cannot be pulled out, resulting in impaired workability. Therefore, it is necessary to apply a hot rolling lubricant excellent in hot lubricating performance to the outer surface of the mandrel bar.

As such a lubricant, a lubricant which is inexpensive and has a very excellent lubricating performance, for example, Japanese Patent Publication No. 59-59
The water-soluble lubricant containing graphite as the main component as shown in Japanese Patent No. 37317 is most often used.

[0005]

However, when mandrel mill rolling is carried out by inserting the mandrel bar coated with the above graphite-based lubricant, carburization occurs on the inner surface of the pipe during rolling, and the carbon concentration on the inner surface of the pipe is high. Part occurs. In this high carbon concentration region, although carbon is diffused by subsequent reheating, finish rolling, and solution treatment after rolling, the carburized region spreads and the concentration itself decreases, but there is still a portion with a high carbon concentration. To do. This carburized layer having a high carbon concentration causes a locally abnormally hardened portion on the inner surface of the pipe after rolling, which reduces the machinability of the product and also reduces the corrosion resistance.

[0006] Therefore, for a product such as a steel pipe made of stainless steel or alloy steel, which is required to secure intergranular corrosion resistance, a step of polishing and removing the carburized portion on the inner surface of the rolled pipe is required. There were problems such as a significant increase in cost and a drop in productivity. Further, in the case of a product having a small diameter, it may not be possible to insert a grindstone for polishing into the pipe due to its small inner diameter, and it may be practically impossible to manufacture the product.

In order to solve such a problem, as disclosed in JP-A-64-16894, a particulate oxide-based layered material and a boric acid-based binder are mixed in a ratio of 1: 0.1 to 1: 0.1.
Non-graphite type lubricants mixed in a weight ratio of 0.5 have been developed. However, when such a non-graphite lubricant is used for mandrel mill rolling of a steel pipe made of stainless steel or alloy steel, the content of the particulate oxide layered substance which is a solid lubricant component is too large. Therefore, there is a problem that scratches caused by this solid lubricant often occur on the inner surface of the pipe. When such scratches occur, even if they are slight, stainless steel and alloy steel products are required to have a beautiful surface, so they are not suitable for some applications and must be polished and repaired. Post-processing is required. Further, when the surface flaw is deep, it is necessary to scrap the product as a defective product, resulting in a decrease in manufacturing yield and a large economic loss.

Further, Japanese Patent Publication No. 1-57719 discloses a non-graphite type lubricant containing phosphoric acid as an essential component, and this lubricant has excellent lubricity and causes the above-mentioned scratches. There is no fear. However, since this lubricant contains phosphoric acid as an essential component, it has the drawback that phosphorus is generated and the quality of the product deteriorates.

The object of the present invention has been made in view of the above-mentioned circumstances, and it is possible to significantly reduce the occurrence of scratches as well as the occurrence of carburization and phosphorus, and the excellent lubricity. A non-graphite type lubricant composition for high temperature processing and a method of using the same.

[0010]

DISCLOSURE OF THE INVENTION The inventors of the present invention are of a non-graphite type which does not cause carburization or phosphorus and has excellent lubricity at the time of pipe making, and which does not cause scratches. As a result of various experimental studies aimed at developing a lubricant, the following was found.

A specific particulate oxide-based layered material and a specific binder having a melting point of 1000 ° C. or less are mixed in a ratio of 1: 4 to.
When mixed in a weight ratio of 1: 1, that is, when the mixing ratio of the binder is greatly increased over that of the lubricant composition disclosed in JP-A-64-16894, carburization and phosphorus carburization do not occur. It has been found that a lubricant composition for high temperature processing can be obtained which not only exhibits excellent lubricity but also significantly reduces the occurrence of scratches.

The present invention has been made based on the above findings, and the gist thereof resides in the following (1) lubricant composition for high temperature processing and (2) method of using the same.

(1) One or more kinds of particulate oxide-based layered substances selected from potassium tetrasilicon mica, sodium tetrasilicon mica, natural gold mica, bentonite, montmorillonite and vermiculite. , Boron oxide, boric acid, alkali metal borate, sodium carbonate,
Characterized by blending potassium carbonate and one or more binders selected from sodium silicate or potassium silicate having a melting point of 1000 ° C. or less in a weight ratio of 1: 4 to 1: 1. And a lubricant composition for high temperature processing.

(2) A method of using the lubricant composition for high temperature processing according to the above (1), characterized in that the lubricant composition for high temperature processing is dispersed and dissolved in water in a weight ratio of 20 to 80. A method of using the lubricant composition for high temperature processing.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, potassium tetrasilicon mica [KMg _2.5 (Si ₄ O ₁₀ ) F ₂ ] and sodium tetrasilicon mica [NaMg _2.5 ] are used as the base material of the lubricant composition for high temperature processing. (Si ₄ O ₁₀ ) F ₂ ], natural gold mica [KMg ₃ (AlSi ₃ O ₁₀ ) (OH) ₂ ], bentonite [Si ₂ (Al _3.34 Mg _0.44 ) O ₂₀ (OH)
₄ Na _0.44 ], montmorillonite [(Na, K, Mg,
Ca) _0.33 Al ₄ (Si _7.33 Al _0.67 ) O ₂₀ (OH) ₄
.NH ₂ O] and vermiculite [(Mg, Fe)
_{3 (Si, Al, Fe)} 4 O 10 (OH) 2 · 4H 2 O]
It is one or more kinds of particulate oxide-based layered substances selected from the above.

Each of these particulate oxide-based layered substances is a natural or artificial layered oxide mineral having a low cutting resistance, and the pipe material and the mandrel bar are seized during pipe making, especially in mandrel mill rolling. It is responsible for preventing In addition, these particulate oxide-based layered materials show substantially the same friction behavior when used as a solid lubricant. Therefore, when two or more of these are mixed and used, the mixing ratio is not particularly limited.

Regarding the size of these oxide-based layered materials, it is desirable that the average particle diameter is 100 μm or less, more preferably 40 μm or less, and the purity is 81% or more. This is because if the average particle size exceeds 100 μm, the dispersibility becomes poor when mixed with water, and the supply to the lubricated surface during use becomes poor. Further, if the purity is less than 81%, the lubricity is impaired by impurities mainly containing inorganic substances such as alumina (Al ₂ O ₃ ) and silica (SiO ₂ ) which are present as impurities. It is not necessary to set the lower limit of the average grain size, but if it is too small, it will be smaller than the surface roughness of the processing tool, and it will remain in the recesses on the tool surface, and Since it is not supplied to the contact portion, the thickness is preferably 1 μm or more.

Other similar layered oxide materials such as white mica [KAl ₂ (AlSi ₃ O ₁₀ ) (OH) ₂ ], kaolin [Al ₂ O ₃ .2SiO ₂ .2H ₂ O], pyrophyllite [Al. _{2 O 3 · 4SiO 2 · H} 2 O], in the case of using a talc _{[3MgO · 4SiO 2 · H 2} O] is a high lubricity performance comparable to graphite-based lubricants such as achieved in the present invention Can't get It is presumed that this is because the interlayer bond strength is stronger than that of the layered oxide material used in the present invention.

With only the particles of the above oxide-based layered material,
Like graphite, it is difficult to firmly adhere to the surface to be lubricated, so a binder is mixed with this. The binder melts at a high processing temperature to become a viscous liquid, and evenly disperses the layered oxide particles, which are the main agent, on the friction surfaces of the tool and the material to be processed and firmly adheres them, and also as a lubricating film itself. To work.

The binder used in the present invention in combination with the above oxide-based layered material is a low-melting-point binder, that is, a boric acid-based binder having a melting point of 1000 ° C. or lower (boron oxide, boric acid, alkali metal borate). It is preferable to use one or more selected from the group consisting of carbonate binders of sodium or potassium and silicate binders (sodium carbonate, potassium carbonate, sodium silicate, potassium silicate). found. This is Mannesmann
In the manufacture of a seamless steel pipe by the mandrel mill method, as described above, a mandrel bar coated with a lubricant is inserted into a hollow shell at 1100 to 1200 ° C. for lubrication,
At this time, the binder melts itself and acts as a fluid lubricating film, and also acts to smoothly supply the layered oxide particles to the entire friction surface. However, its melting point is 1000 ° C
When the temperature exceeds the above range, the layer does not melt sufficiently in the hot working temperature range (800 to 1200 ° C.), so that the layered oxide particles cannot be uniformly dispersed over the entire surface to be rubbed, and the lubricity is remarkably lowered.
This does not occur at 1000 ° C or lower. More preferably, it is optimal to use a binder having a melting point of 500 to 900 ° C.

Specifically, sodium silicate and potassium silicate are generally classified by the molar ratio as shown in Table 1, and their melting points are as shown in Table 1. Therefore,
Sodium silicate and potassium silicate which can be used in the present invention are No. 2 having a molar ratio of Na ₂ O and SiO ₂ of 1: 2.
And No. 3, which is 1: 3, No. 5 in which the molar ratio of K ₂ O and SiO ₂ is 1: 1, and No. 7, which is 1: 3,
It is No. 8 which is 1: 4.

[0022]

[Table 1]

The melting point of boron oxide (B ₂ O ₃ ) is about 4
At 50 ° C., orthoboric acid (H ₃ BO ₃ ), metaboric acid (HBO ₂ ), pyroboric acid (H ₂ B ₄ O ₇ ) can be used as boric acid,
When they are heated, they lose water one by one, and B ₂ O near 300 ° C.
Becomes ₃ . As the alkali metal borate, lithium borate, sodium borate, potassium borate, borax (Na ₂ B
₄ O ₇ · 10H ₂ O) such as metaborate or pyroborate can be used, and their melting points are 843 ° C. and
966 ° C, 947 ° C and 878 ° C. Furthermore, the melting point of sodium carbonate is 849 ° C., and the melting point of potassium carbonate is 891.
C. and both are 1000.degree. C. or less.

It is desirable that the purity of these binders is 85% or more. This is because if the purity is less than 81%, the lubricity is impaired by impurities mainly composed of inorganic substances such as alumina (Al ₂ O ₃ ) and silica (SiO ₂ ).

The size of the binder is not particularly limited when the lubricant composition of the present invention is used as a mixture with water. This is because when the lubricant composition is dispersed in water, the binder disperses and dissolves in water. However, when the lubricant composition is used without being mixed with water, it is preferable to use a binder having an average particle size of 100 μm or less in order to improve the uniform dispersion and mixing property with the lubricating base material. Is desirable.

The above oxide-based layered material of the lubricating base material (hereinafter,
The mixing ratio of the A substance) and the binder (hereinafter referred to as the B substance) is a weight ratio of 4 to B substance to 1 to A substance.
1. In other words, substance A: substance B is 20:80 to 50: 5
It is in the range of 0. This is because when the compounding ratio of the substance B, which is a binder, exceeds 80 parts by weight, seizure occurs during pipe production, and conversely 5
If it is less than 0 parts by weight, a sufficient reduction in the friction coefficient cannot be achieved, and not only satisfactory lubricating performance cannot be obtained, but also the broken A substance particles in a layered state during its use aggregate. Then scratches occur. The preferred mixing ratio is in the range of 30:70 to 40:60 of A substance: B substance.

The lubricant composition of the present invention prepared by blending the substances A and B can be used by directly supplying it to the surface to be rubbed, but it is preferable to use it by dispersing and mixing it in water.

In the case where the lubricant composition is used by being dispersed and mixed in water, the ratio of dispersion and mixing is 1: 0.1 by weight of the lubricant composition to 1 part of water.
The range is 25 to 4. That is, when the weight ratio of the lubricant composition is less than 0.25, the lubricant composition is inferior in stability and the substance A particles settle early.
On the other hand, when the weight ratio of the lubricant composition is more than 4, the viscosity at room temperature increases, and the substance A cannot be uniformly dispersed and applied to the tool surface such as a mandrel bar. The lubricant composition which is dispersed and mixed in water and applied to the surface of a tool such as a mandrel bar by spraying or any other suitable method is dried and solidified, and then subjected to hot working such as pipe forming work.

The lubricant composition of the present invention is not limited to the mandrel mill rolling of the above-mentioned stainless steel or alloy steel pipe, but it is inconvenient if there is carburization or phosphorus-incorporating low alloy steel or carbon steel pipe. Needless to say, it can be used for various hot rolling of, or hot forging such as forged products.

[0030]

[Examples] Any one of potassium tetrasilicon mica, sodium tetrasilicon mica, natural gold mica, montmorillonite, white mica, kaolin, pyrophyllite, and talc crushed to an average particle size of 30 μm as an oxide-based layered material, and as a binder Adjust the lubricant composition by mixing silicates or carbonates of sodium or potassium with different melting points and also boric acid type binders (boron oxide, boric acid, alkali metal borate) at various mixing ratios. Then, these lubricant compositions were dispersed in water in the proportions shown in Tables 2 and 3 and mixed and adjusted. Then, the lubricant composition dispersed in water and mixed and adjusted was applied to the surface of the mandrel bar having an outer diameter of 140.5 mm at room temperature with a brush to apply a film thickness of about 100 μm,
A mandrel bar dried at room temperature was prepared. Then, in the manufacturing process of the seamless steel pipe by the Mannesmann-mandrel mill method using these mandrel bars, it is made of stainless steel (SUS304) and has an outer diameter of 181.0 mm,
A 1100 ° C hollow shell with a wall thickness of 16.0 mm and a length of 7000 mm was used with a 7-stand mandrel mill to obtain an outer diameter of 15
It was stretch-rolled to a thickness of 1.0 mm, a thickness of 5.0 mm and a length of 25300 mm.

Then, the coefficient of friction of each lubricant composition during mandrel mill rolling and the occurrence of scratches and seizures after rolling were visually evaluated. The results are also shown in Tables 2 and 3.

The friction coefficient was determined by the following formula by measuring the total load ΣP _i and the thrust force F acting on the mandrel bar in a steady state in which loads were applied to all stands during mandrel mill rolling.

Friction coefficient = F / ΣP _i …………………… In addition, both scratches and seizure flaws were evaluated in terms of the occurrence of scratches. The case of partial occurrence is shown as Δ, and the case of large amount of defects is shown as ×.

[0034]

[Table 2]

[0035]

[Table 3]

As shown in Tables 2 and 3, when the mandrel bar coated with the lubricant composition (No. 1-16) of the present invention was used, the coefficient of friction during mandrel mill rolling was 0. It was as low as 082 or less, and seizure flaws and scratches were hardly generated. In the examples of the present invention,
Nos. 1 to 3 are Nos. 4 to 9 and Nos. 13 to 13 when the compounding ratio of the oxide layered material as the base material and the binder is changed.
No. 16 is when the kind of the binder is changed, and No. 10-12 is when the kind of the oxide-based layered material as the base material is changed.

On the other hand, the lubricant composition of the comparative example (No.
When the mandrel bar coated with 17 to 30) was used, the inner surface quality of the product was poor in all cases. That is, in Comparative Examples Nos. 17 and 18, the amount of the oxide-based layered material as the base material was large and the friction coefficient was low, and seizure flaws hardly occurred, but the amount of the base material was too large, so that the solid A lot of scratches caused by the lubricant were generated. Also, N
In No. 19, the amount of the oxide-based layered material as the base material was small and scratches did not occur, but the amount of the base material was too small and the friction coefficient was high, so that a large amount of seizure flaws were generated. Further, in Nos. 20 to 23 and Nos. 27 to 30, since the oxide-based layered material of the base material is other than the one specified in the present invention, the friction coefficient is high and a large amount of seizure flaws and scratches are present. Occurred. Furthermore, in Nos. 24 to 26, the melting point of the binder is more than 1000 ° C., the friction coefficient is high, and the oxide-based layered material of the base material is agglomerated, resulting in a large amount of seizure flaws and scratches. Occurred in.

Although data is not shown, when the lubricant composition was dispersed and mixed in water in a weight ratio of more than 4, the viscosity was high and the application to the mandrel bar was impossible. .

[0039]

EFFECTS OF THE INVENTION The lubricant composition for high temperature processing of the present invention exhibits good lubricity and does not contain graphite or phosphoric acid.
There is no inconvenience such as forming a carburized layer or a phosphorized layer on the work material. Further, since scratches do not occur, a product having excellent surface quality can be obtained. Therefore, the step of polishing or cutting and removing the carburized layer or the phosphorized layer and the step of cleaning the scratches and the seizures are unnecessary, or the number of maintenance steps can be significantly reduced.

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Claims (2)

[Claims] 1. A particulate oxide-based layered material of one or more selected from potassium tetrasilicon mica, sodium tetrasilicon mica, natural gold mica, bentonite, montmorillonite and vermiculite, and boron oxide,
Boric acid, an alkali metal borate, sodium carbonate, potassium carbonate, and one or more binders selected from sodium silicate or potassium silicate having a melting point of 1000 ° C. or less are used in a ratio of 1: 4 to 1: 1. A lubricant composition for high temperature processing, characterized in that it is blended in a weight ratio. 2. A method for using the lubricant composition for high temperature processing according to claim 1, wherein the lubricant composition for high temperature processing is dispersed and dissolved in water in a weight ratio of 20 to 80 and used. A method of using the lubricant composition for high temperature processing.