JPH0264195A - Seamless steel pipe-producing lubricant containing gilsonite fine powder - Google Patents

Abstract

PURPOSE:To obtain the title lubricant capable of providing water resistance, impact resistance and good lubricating properties by adding a salt of polybasic high-molecular weight acid to a composition consisting of a graphite fine powder, gilsonite fine powder and fine-particle synthetic resin insoluble in water and dispersing the blend into water. CONSTITUTION:The aimed lubricant obtained by adding one or more kind of salts of polybasic high-molecular weight acid selected from (D) humic acid, nitrohumic acid and ligninsulfonic acid to a composition consisting essentially of fine-particle synthetic resin insoluble in water consisting of (A) graphite fine powder, preferably having <= 100mum average particle size, (B) gilsonite fine powder, preferably having <= 100mum average particle size and (C) a resin such as polyacrylic resin, poly(modified)vinyl acetate based resin or polystyrene based, polyethylene based or polyepoxy based resin and dispersing the blend into water.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a water-dispersed hot lubricant for seamless steel pipe manufacturing, particularly to a lubricant for mandrel bars in mandrel mill pipe manufacturing. The present invention relates to a lubricant for mandrel bars which forms a uniform and thick film at temperatures between 400° C. and 400° C., has a dry film with excellent water resistance and impact resistance, and exhibits good lubricity. Therefore, the present invention is useful in the lubricant manufacturing industry and the steel pipe manufacturing industry.

Conventional lubricants for seamless steel pipe manufacturing are generally oil-based lubricants that are made by mixing graphite powder with oil (e.g., heavy oil, waste oil, etc.), or water-dispersed lubricants that are made by dispersing graphite powder in water. It is used.

Oil-based lubricants generate a large amount of smoke or flame, which poses a risk of deterioration of the working environment and fire.

On the other hand, water-dispersed lubricants have been developed to improve the disadvantages of oil-based lubricants. As a water-dispersed lubricant, a composition in which graphite is dispersed in water using a dispersant (Japanese Patent Publication No. 62-1
7639), compositions using synthetic resin as a binder for graphite (JP-A-58-138795, JP-A-59-37317, and JP-A-62-343)
57) and compositions containing powdered gilsonite to improve the adhesion of the film to the mandrel bar surface (JP-A-60-240796, JP-B-Sho 62-
34356) etc. have been published.

However, with such water-dispersed lubricants, if the surface of the mandrel bar is in a high temperature range (100 to 400°C), a uniform and thick film cannot be obtained during spray application.
There was a drawback that sufficient lubrication effect was not exhibited.

Problems to be Solved by the Invention The present invention solves the drawbacks of the conventional water-dispersed ei agent described above, and improves the mandrel par temperature in the high temperature range (100 to 40
The purpose of the present invention is to provide a lubricant for seamless steel pipe manufacturing that can form a uniform and thick film on the par surface even at 0°C and exhibit extremely good hot lubrication performance.

Means for Solving the Problems In order to achieve this objective, the present inventors conducted various studies on improving the adhesion of graphite to the mandrel bar surface and forming a uniform film, and found that a specific polybasic It has been discovered that by blending a salt of a high molecular weight acid, a thick and uniform lubricant film can be formed, and that it can also be used as a lubricant for seamless steel pipe manufacturing that exhibits extremely excellent lubrication performance.

That is, the gist of the present invention is that fine powder graphite,
Humic acid, nitrofumic acid and lignin sulfonate)/
The present invention relates to a lubricant for seamless steel pipe manufacturing, characterized in that the lubricant contains one or a mixture of salts of two or more acids selected from acids and is dispersed in water.

(Salt of polybasic high molecular weight acid) Salts of polybasic high molecular weight acids in the present invention include sodium salts, potassium salts, calcium salts, magnesium salts of humic acid, nitrofumic acid and ligninsulfonic acid;
Ammonium salts, amine salts, etc. are suitable. These salts can be used alone or in combination of two or more. The amount of these salts added is determined so that the concentration of these salts in the aqueous dispersion is 0. Suitably, the content is in the range of OI to 5% by weight. If the amount added is less than 0.01% by weight, it is difficult to achieve the effects of the present invention.

(Fine powder graphite) The fine powder graphite used in the present invention may be a natural product, a synthetic product, earth-like, or scale-like, but the average particle size is determined from the viewpoint of dispersion stability of graphite and maintenance management of the lubricant supply device. from】
It is desirable that the thickness is 00 μm or less.

(Fine powder gilsonite) In the present invention, it is necessary to use fine powder gilsonite. If other asphalts are used, the adhesion will be reduced during film formation, and especially the amount of adhesion and adhesive strength will be extremely poor during reapplication.

The average particle size of fine powder gilsonite is determined from the viewpoint of dispersion stability of gilsonite and maintenance management of lubricant supply equipment.
It is desirable that the diameter is 100 μm or less, and the amount added is suitably in the range of 5 to 30% by weight in the aqueous dispersion.

(Fine Particulate Synthetic Resin) As the particulate synthetic resin used in the present invention, commonly used ones can be used. Examples thereof include polyacrylic resins, polyvinyl acetate resins, polymodified vinyl acetate resins, polystyrene resins, polyethylene resins, polyepoxy resins, and the like.

(Optional Additives) The lubricant of the present invention is basically composed of finely powdered graphite, finely powdered gilsonite, synthetic resin, and a salt of a polybasic high molecular weight acid. For the purpose of dispersion, other ingredients such as surfactants, polymeric dispersants,
Addition of pH adjusters, thickeners, etc. does not reduce the effects of the present invention, and they can be added as desired.

EXAMPLES In order to make the present invention easier to understand, examples are shown below.

Example 1 The results of examining the adhesion properties (amount of adhesion and film uniformity) of the compositions shown in Table 1 are shown in FIG. 1 and Table 2.

The lubricant is applied to the mandrel bar while the mandrel bar is moving (moving speed 1 to 4 m/s). Taking this into consideration, adhesion experiments were conducted under dynamic test conditions as shown below.

After spraying the sample onto a steel vibrator ($90 x 4t x 150 Lmm) heated to a predetermined temperature and moving at a speed of 2.0 m/s, the adhesion film ffi (g) on the surface of the steel vibrator was measured.
and the uniformity of the film.

The spray conditions are as follows.

Pump: Airless pump 206T (made by Graph),
Compression ratio 10:1 Spray gun: 24 AUA automatic gun [manufactured by Spray Ink Systems Co.] Nozzle: φ0.61 mm Spray distance: 200 mm Discharge pressure: 40 K g f / cd discharge amount
: 30 g/s Steel pipe temperature: 60 to 400°C Sample oil dilution liquid: Each sample oil was spray applied as an aqueous dispersion with a concentration of 45% by weight.

Coating amount (g): Number of measurements: 5 Table 1 Sample composition Table 2 Uniformity of coated film Note) (1) Sample A is an example of the invention of JP-A No. 60-240796, and sample B is a special This is an embodiment of the invention disclosed in Publication No. 62-34356.

(2) Samples 1 to 5 are lubricants of the present invention.

(3) Numbers in the table represent parts by weight.

(4) Tg indicates the glass transition point.

Note) × indicates that the film is very non-uniform, O indicates that an undried film is formed, and 0 indicates that the dry film is very dense and uniform.

Example 2 (Sample 1) Natural graphite (earth-like) Gilsonite 70 weight 1 part, 10 parts by weight, polyacrylic resin 20 parts by weight, humic acid ammonium salt 0.02 parts by weight The above composition was 45 parts by weight. A dispersion containing water was continuously applied (200 pieces) to hot rolling of seamless steel pipes using a mandrel mill, and the lubricant was applied by airless spraying to a mandrel bar moving at a speed of 2.0 m/s. The mandrel bar surface temperature at that time was 100 to 250°C, the lubricant film was uniform and well adhered, and the film thickness was 30 to 40 μm.
) formed a more uniform and thicker film than prior art lubricants. As a result, the friction coefficient was 80% or less compared to the comparative example, and improvements such as reduction in mill driving power (about I5%) and stabilization of rolling were obtained.

Example 3 (sample sample 2) Natural graphite (raw) 70 parts by weight.

A dispersion of 10 parts by weight of gilsonite, 20 parts by weight of polyvinyl acetate resin, 0.05 parts by weight of sodium humate salt, and 45 parts by weight of the above composition was prepared by adding water to a seamless steel pipe using a mandrel mill. Continuously applied to hot rolling (30
The lubricant was applied by airless spraying to a mandrel bar with a moving speed of 2.0 m/s. The mandrel bar surface temperature at that time was 150 to 350°C, and the lubricant film was uniform and adhered well, and the film thickness was 40 to 50 μm, which was more uniform than the conventional lubricant as a comparative example (comparative example A). A thick film was formed. As a result, the friction coefficient is 75% or less compared to the comparative example, and the mill drive power is reduced (approximately 20%
%) and improved stability of rolling.

Example 4 (sample oil sample 3) Natural graphite (raw) 70 heavy plates.

Gilsonite 10 parts by weight, polyvinyl acetate resin 19.5 parts by weight, nitrofumic acid ammonium salt 0.5 parts by weight The above composition was mixed with water to make 45 parts by weight, and a dispersion of the above composition was mixed with seamless copper using a mandrel mill. The lubricant was applied continuously (400 tubes) during hot rolling of tubes by airless spraying to a mandrel bar with a moving speed of 2.0 m/s. At that time, the mandrel bar surface temperature was 150 to 350°C. The IW lubricant film was uniform and adhered well, with a film thickness of 40 to 55 μm, which was more uniform and thicker than the prior art lubricant as a comparative example (Comparative Example A). As a result, the friction coefficient is 75% or less compared to the comparative example, and the mill drive power is reduced (approximately 20%).
, improvements such as stabilization of rolling were obtained.

Example 5 (Sample 111a4) Natural graphite (raw) 70 parts by weight, Gilsonite 10 parts by weight.

Polyacrylic resin] 9 parts by weight.

A dispersion of 1 part by weight of lignin sulfonic acid sodium salt and 45 parts by weight of the above composition was continuously applied to hot rolling of seamless steel pipes using a mandrel mill.
The lubricant was applied by airless spraying to a mandrel bar with a moving speed of 2.0 m/s. The mandrel bar surface temperature at that time was 150 to 300°C, and the lubricant film was uniform and adhered well, with a film thickness of 45 to 55 μm, which was superior to the conventional lubricant as a comparative example (Comparative Example B).
A uniform and thick film was formed. the result.

Compared to the comparative example, the coefficient of friction was 70% or less, and improvements such as reduction in mill drive power (about 20%) and stabilization of rolling were obtained.

Example 6 (Sample 5) Natural graphite (raw) 70 parts by weight, gilsonite 10 parts by weight, polyacrylic resin 17 parts by weight, humic acid ammonium salt 2 parts by weight, ligninsulfonic acid sodium salt 1 part by weight. A dispersion of the above composition in which water was added to give 45 parts by weight was continuously applied (400 pipes) to hot rolling of seamless steel pipes using a mandrel mill. The lubricant was applied by airless spraying using a mandrel bar moving at a speed of 2.0 m/s. The mandrel bar surface temperature at that time was 150
At ˜350° C., the lubricant film was uniform and adhered well, with a film thickness of 45 to 55 μm, forming a more uniform and thicker film than the prior art lubricant as a comparative example (Comparative Example B). the result.

Compared to the comparative example, the coefficient of friction was 70% or less, and improvements such as reduction in mill drive power (about 20%) and stabilization of rolling were obtained.

Effects of the Invention A lubricant for seamless steel pipe construction whose main components are graphite powder, gilsonite, and fine-grained synthetic resin has poor adhesion and does not produce a uniform dry film when the surface temperature of the mandrel bar is high (150°C or higher). However, the lubricant for seamless steel pipes containing one or a mixture of two selected from salts of humic acid, nitrofumic acid, and ligninsulfonic acid, which are polybasic high molecular weight acids, of the present invention is , forms a uniform and thick dry film and exhibits good rolling lubrication performance. Therefore, by using the lubricant of the present invention, it is possible to reduce mill drive power, stabilize rolling, etc.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the adhesion of the lubricant of the present invention and the lubricant of the prior art.

Claims (2)

[Claims] (1) A composition whose main components are finely powdered graphite, finely powdered gilsonite, and water-insoluble fine particulate synthetic resin contains a salt of a polybasic high molecular weight acid and is dispersed in water. A lubricant for seamless steel pipe construction. (2) The seamless steel pipe structure according to claim 1, wherein the polybasic high molecular weight acid salt is a mixture of salts of one or more acids selected from humic acid, nitrhumic acid, and ligninsulfonic acid. Pipe lubricant.