JP2002338984A - Hot-working powder lubricant composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a hot-working powder lubricant composition which exhibits improved properties when it is in a powdery state and which decreases the friction with a work material. SOLUTION: This lubricant composition is used in hot working, is prepared by mixing 40-90 mass% sodium borate pentahydrate, 6-30 mass% sodium carbonate, and 5-30 mass% at least one kind of sodium or calcium salt of a fatty acid, and may further contain 1-30 mass % sodium molybdate. The composition, when it is in a powdery state, has good properties, can be uniformly applied to a predetermined rolling position, and can reduce the friction on a work surface during hot working; therefore, the work surface is made beautiful and energy saving can be achieved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot powder lubricant composition which is applied to the inner surface of a hollow shell for use in, for example, mandrel mill rolling in the process of manufacturing a seamless pipe.

[0002]

2. Description of the Related Art Mandrel mill rolling, for example, involves a process of manufacturing a seamless pipe in a process of forming a drilled piece of 1000 to 1 perforated in a previous step.
In this process, a mandrel bar is inserted into a hollow shell at 300 ° C., rolled to a predetermined thickness by several steps of a hole type roll (usually 5 to 8 steps), and stretched.

[0003] When the hollow shell is stretched, a relative slip occurs between the inner surface of the hollow shell and the surface of the mandrel bar. Therefore, during rolling, a lubricant is applied to the inner surface of the hollow shell and the surface of the mandrel bar. However, among these lubricants, as a lubricant used by being applied to the surface of a mandrel bar, a so-called graphite-based lubricant mainly composed of graphite as disclosed in JP-A-50-144868, and a lubricant disclosed in There is known a non-graphite composition mainly composed of an oxide layer material such as No. 16894.

On the other hand, lubricating agents attached to the inner surface of the hollow shell include pickling agents having lubricity as disclosed in Japanese Patent Publication No. 7-86667 and graphite as disclosed in JP-A-6-184573. Sodium carbonate two-component lubricant
Lubricant mainly composed of metal carbonate and alkali metal carboxylate as disclosed in JP-A-41474
No. 91 lubricants mainly composed of alkali metal borates and iron oxides are known. However, in any case, particularly in the retained-mandrel mill rolling, the friction coefficient and the inner surface quality can be sufficiently satisfied. Not in.

Particularly, in a full-retract mandrel mill, which has become widespread in recent years, since a long tube is manufactured using a short bar, if the friction coefficient is large, the load on the bar becomes large, and seizure easily occurs. As a result, not only does the inner surface quality deteriorate, but also a larger amount of power is consumed.

The properties of the powdery lubricant are also important so that the lubricant does not solidify during storage, has poor fluidity, makes it difficult to convey, or cannot be uniformly applied to the inner surface of the raw tube. It is.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and has been made to improve the properties at the time of powdering, for example, by reducing the friction between a hollow shell and a mandrel bar. It is another object of the present invention to provide a hot powder lubricant composition that can clean the inner surface of a product and achieve energy saving.

[0008]

In order to achieve the above object, a hot powder lubricant composition according to the present invention contains 40 to 90% by mass of sodium pentahydrate and 6 to 6% of sodium carbonate. 30% by mass, 5 to 30% by mass of at least one kind of Na or Ca salt of a fatty acid, and 1 to 30% by mass of sodium molybdate. By doing so, the properties at the time of the powder become good, the friction on the processed surface is reduced, the processed surface of the product becomes beautiful, and energy saving can be achieved.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The inventors of the present invention have conducted intensive studies on the problems of the conventional hot powder lubricant composition as described above, A hot powder lubricant composition that can be uniformly applied to a processing position and that can reduce friction during hot working has been invented.

That is, the hot powder lubricant composition according to the present invention is a lubricant composition used in hot working, comprising 40 to 90% by mass of sodium pentahydrate and 6% of sodium carbonate. To 30% by mass, and 5 to 30% by mass of at least one kind of Na or Ca salt of a fatty acid,
If necessary, further add sodium molybdate to 1-3
0% by mass.

The hot powder lubricant composition according to the present invention has good properties when powdered, can be uniformly applied to a predetermined processing position, and can reduce friction of a processing surface during hot processing. The processed surface of the product becomes beautiful and energy saving can be achieved.

In the hot powder lubricant composition according to the present invention, 40 to 90% by mass of sodium pentahydrate of sodium borate is blended as a main component of the lubricant, as the fluid lubricant and the scale melting agent. This is to exert the effect. That is, if it is less than 40% by mass, the other active ingredients are incorporated in too much, and the viscosity becomes low, resulting in poor lubricity.
On the other hand, if it exceeds 90% by mass, other components become too small, so that not only can the friction coefficient not be reduced,
This is because the properties at the time of the powder deteriorate. According to experiments and studies by the present inventors, more favorable results were obtained when the amount was 50 to 80% by mass.

[0013] In addition, by mixing sodium carbonate, its viscosity is reduced, it spreads evenly on the work surface, and it exhibits lubricity without unevenness. Further, when a scale causing a flaw is generated on the processed surface, the scale also has an effect of quickly melting. However, when the compounding amount is less than 6% by mass, the viscosity cannot be reduced and the lubricity cannot be exhibited without unevenness. On the other hand, if it exceeds 30% by mass, the viscosity becomes too low, and consequently the lubricity deteriorates. Therefore, in the present invention, the blending amount of sodium carbonate is set to 6 to 30% by mass. According to experiments and studies by the present inventors, more favorable results were obtained when 10 to 20% by mass was added.

As mentioned above, sodium pentahydrate of borate acts as a lubricant, but by adding sodium molybdate, lubricity is further improved and a friction coefficient can be reduced.

The amount of the sodium molybdate is as follows:
If it is less than 1% by mass, there is no effect in reducing the coefficient of friction, and
If the amount exceeds 30% by mass, the viscosity becomes too low to uniformly adhere, and as a result, the lubricating property is deteriorated. . According to experiments and studies by the present inventors, more favorable results were obtained when 5 to 25% by mass was added. By mixing the above-mentioned compositions, it becomes possible to reduce the friction coefficient comprehensively.

Further, in the present invention, the pentahydrate of sodium borate is limited to improve the properties at the time of powdering (solidification during storage, fluidity during transportation, etc.) and simultaneously spread at the time of coating. This is because it is possible to maintain sex.

That is, since the anhydrous sodium borate salt does not contain water of crystallization when adhered to a high-temperature workpiece, it does not foam at all, so it does not spread uniformly and is unsuitable as a hot lubricant. . In order to apply the coating uniformly, the specific gravity is large, so that it has to be introduced in a large amount, which is not only uneconomical, but if it is too large, it may remain on the coated surface, deteriorating the quality.

Further, sodium decahydrate of borate is 50
Since the water of crystallization starts to be discharged from around ℃, the water dissolves sodium carbonate and sodium borate themselves and condenses due to the adhesive action. In particular, since the lubricant is used in a place where a high-temperature workpiece is handled, solidification in the piping poses a problem. Also, when thrown into a hot workpiece,
Since it contains more crystallization water than pentahydrate, foaming is more intense than pentahydrate, and foaming is too large to be sufficiently adhered to a predetermined position due to wind pressure at the time of charging, and is uneconomical.

The Na and Ca salts of fatty acids are essential for maintaining the good properties of the lubricant in powder form. However, when the compounding amount is less than 5% by mass, the material is not smoothly transferred in the pipe during the transfer, and a load is imposed on the transfer machine, which causes a trouble. On the other hand, when the content exceeds 30% by mass, when the powder lubricant is charged into a high-temperature workpiece, it burns instantaneously, and the combustion gas diffuses the powder lubricant itself too much and is discharged out of the workpiece. As a result, the amount of adhesion is reduced, not only the lubricity is deteriorated, but also uneconomical. Therefore, in the present invention, the content is set to 5 to 30% by mass.

[0020]

EXAMPLES The effects of the present invention will be described below with reference to examples. (Example 1) The composition of the product of the present invention is shown in Table 1 below, the composition of a comparative product of the product of the present invention is shown in Table 2, and the conventional examples are shown in Table 3 (Conventional examples 1 and 2 are compositions of Japanese Patent Publication No. 7-84667). , Conventional examples 3 and 4
Represents the composition of JP-A-6-184573, and Conventional Example 5 represents the composition of JP-A-2000-226591).

The contents of the components used in this example are as follows. Sodium borate pentahydrate _{(Na 2 B 4 O 7 ·} 5H 2 O):
The average particle size of about 0.4 mm, sodium purity of 98% or more molybdate (Na ₂ MoO ₄ · 2H ₂
O): average particle size about 0.3 mm, purity 98% or more

Sodium carbonate (Na ₂ CO ₃ ): average particle size of about 0.3 mm, purity of about 99% Na salt of fatty acid (Na salt of tallow fatty acid): average particle size of about 0.3 mm, purity of about 95% of fatty acid Ca salt (Ca salt of stearic acid): average particle size
About 0.4mm, about 97% purity

[0023]

[Table 1]

[0024]

[Table 2]

[0025]

[Table 3]

The evaluation results of the hot powder lubricant compositions shown in Tables 1 to 3 above are shown in Table 4 below, and the examples of the present invention shown in Table 1 are all examples. It can be seen that both powder properties (powder solidification and powder flowability) and friction coefficient are superior to the comparative examples shown in Table 2 and the conventional examples shown in Table 3.

The lubricant performance shown in Table 4 below is the result of an investigation by the following method. 1) Solidification during powder storage 50 g of a sample was weighed in a Petri dish, and allowed to stand in a 60 ° C constant temperature bath for 24 hours to observe the state of solidification. The evaluation was ◎ for those that had not solidified at all, ○ for those that had solidified a little, and X for those that had solidified.

2) Fluidity of powder Evaluated by measuring the angle of repose (Hosokawa equation). In the evaluation, the angle of repose was less than 38 degrees, and the angle of repose was 38 to 42
When the angle of repose was less than 42 degrees, the result was less than 42-46 degrees, and when the angle of repose was 46 degrees or more, x.
And

3) Fluidity at High Temperature 150 mm × 150 m in an electric furnace set at 1100 ° C.
After placing an mx 5 mm test piece (SS400 and SUS304) for 15 minutes, place a 0.2 g sample on the test piece, tilt it at 30 °, hold it for 30 seconds, take it out of the electric furnace, observe the fluidity did. In the evaluation, those that spread very well were evaluated as ◎, those that spread very well, those that flowed a little, and those that did not spread or those that flowed too much were evaluated as x.

4) Coefficient of friction Evaluation was made by a ring compression test method under the following conditions. Ring specimen material: SS400 Ring shape: inner diameter 15mm, outer diameter 30mm, thickness 10m
m Ring heating temperature: 1100 ° C Die material: SKD-61 Target compression ratio: 55%

Test procedure: A graphite-based coating lubricant was applied to the die (target adhesion amount: 10 g)
/ M ² ). The sample is applied to the heated ring specimen and compressed by a press. Calculation of friction coefficient: ΔD = mln (μ / 0.055) Inm = (0.044 × compression ratio) +1.06 where μ is a friction coefficient, ΔD is a change in inner diameter, and m is a variable obtained from the compression ratio. Show. The evaluation was evaluated as μ when μ was less than 0.06, ○ when μ was less than 0.06 to 0.08,
Is 0.08 to less than 0.10, and Δ is 0.10 or more.

[0032]

[Table 4]

(Example 2) Of the lubricants whose lubricating performance was evaluated in Example 1 described above, four examples of the present invention were used.
Lubricating performance was investigated using three types of each of the comparative example and the conventional example in an actual mandrel mill rolling line. The results are shown in Table 5 below. As is clear from Table 5, even when applied to an actual machine, the embodiment of the present invention is superior in both the coefficient of friction and the inner surface quality as compared with the comparative example and the conventional example. You can see that

The rolling conditions for obtaining the following Table 5 are as follows. Rolling device: 5 stand full retract mandrel mill Rolled material: 13% Cr steel Temperature before rolling of rolled material: 1150 ° C

Hollow shell dimensions before mandrel mill rolling: outer diameter 330 mm, wall thickness 23 mm, length 6000 mm dimensions after mandrel mill rolling: outer diameter 276 mm, wall thickness 13 mm, length 12000 mm mandrel bar: outer diameter 248 mm, length: 24000 mm Material: SKD6, Surface: Cr plating (50 μm thickness) A graphite-based lubricant is applied to the surface of the bar and dried.

Lubricant injection method: 1.5 kg / cm ² N ₂ carrier gas is blown from one end of the hollow shell. Lubricant injection amount: 2000cm ^{3 in} total

The coefficient of friction and the quality of the inner surface shown in Table 5 below are the results of evaluation as described below. 1) Coefficient of friction The coefficient of friction was evaluated as a value obtained by dividing the retained force of the mandrel bar by the sum of the load of each stand. The evaluation was such that the above value was 0.
03 or less, ◎: 0.031 to 0.04, Δ: 0.041 to 0.05, and ×: 0.051 or more.

2) Inner Surface Quality The inner surface quality was evaluated based on the rate of occurrence of flaws linearly formed in the pipe inner surface. The evaluation was ◎ when the incidence rate was 0.5% or less, ○ when the incidence rate was 0.5 to 1.0%, and 1.0 to 2.
0% was rated as Δ, and 2.0% or more was rated as x.

[0039]

[Table 5]

In the above embodiment, the hot powder lubricant composition according to the present invention is applied to mandrel mill rolling. However, the hot powder lubricant composition according to the present invention is applied to mandrel mill rolling. Not only that, it can be applied to plugs and the like used in the production of other seamless pipes and used, but it is also applicable to the hot rolling of bar steel, bar steel, wire rod and other hot working. Needless to say.

[0041]

As described above, the hot powder lubricant composition according to the present invention has good properties when powdered, can be uniformly applied to predetermined processing positions, and can be processed during hot processing. Since the friction of the surface can be reduced, the processed surface of the product becomes beautiful and energy saving can be achieved.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) C10M 105/24 C10M 105/24 111/02 111/02 125/00 125/00 125/10 125/10 129 / 40 129/40 // C10N 10:02 C10N 10:02 10:04 10:04 10:12 10:12 20:06 20:06 Z 40:24 40:24 Z (72) Inventor Sumio Iida Osaka 4-5-33 Kitahama, Chuo-ku, Osaka Sumitomo Metal Industries, Ltd. (72) Inventor Kazuo Tanaka 1-11-16 Fukuura, Kanazawa-ku, Yokohama, Kanagawa Prefecture Inside Palace Chemical Co., Ltd. (72) Inventor Shizuo Mori Kanagawa 1-11-16 Fukuura, Kanazawa-ku, Yokohama-shi F-term (reference) in Palace Chemical Co., Ltd. 4H104 AA11A AA11C AA13A AA13C AA26A BB16A BB16C EA08Z FA01 FA02 FA06 PA26

Claims (2)

[Claims] 1. A lubricant composition used in hot working, comprising 40 to 90% by mass of sodium pentahydrate, 6 to 30% by mass of sodium carbonate, and one kind of Na or Ca salt of a fatty acid. A hot powder lubricant composition comprising a mixture of the above components in an amount of 5 to 30% by mass. 2. The method according to claim 1, further comprising adding sodium molybdate to the mixture.
2. The hot powder lubricant composition according to claim 1, wherein the composition contains 0% by mass.