JPS5918799A - Lubricant for hot processing of steel stock - Google Patents

Abstract

PURPOSE:To provide titled lubricant capable of readily forming graphite film of high uniformity and adhesiveness to steel stock, comprising an aqueous suspension prepared by incorporating water with graphite powder and each specific amount of a saturated dicarboxylic acid and a dispersant. CONSTITUTION:The objective lubricant can be obtained by suspending in water, a composition comprising (A) graphite powder, (B) 1-50wt% of a saturated dicarboxylic acid (pref. dodecane dicarboxylic acid), and (C) <=20 (pref. 0.5-10) wt% of a dispersant (e.g., casein, animal base gelatin, gum arabic, alginic acid, starch, CMC, PVA) in such a way that the total solid content accounts for 20wt%. EFFECT:Especially effective in calendering and forging with mandrel.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lubricant for hot working of steel materials. It is already well known that a mixture of graphite and an organic oil such as heavy oil or tar is effective as a lubricant to reduce friction between tools and steel when hot working steel. . However, when these anti-friction agents are used at high temperatures, the heat decomposes the oil content, producing p, smoke, flame, and odor, which poses health and safety problems, and at the same time reduces the lubricating effect. It also becomes. It is also well known that glass is effective as a lubricant for purposes such as reducing friction between the mandrel and the steel material and protecting the mandrel surface during the drilling process in which steel materials are press-drilled using a mandrel to form steel pipes. Are known. However, when glass is used as a lubricant,
The glass fuses to the mandrel during drilling, and as the glass cools after drilling, it becomes solid and difficult to remove. Glass stuck! However, there are problems such as scratches occurring on the inner surface of the steel pipe when the next hole is drilled.

In order for graphite to play the role of a solid lubricant, the effect is more greatly exhibited by forming an appropriate film on the friction surface. However, graphite alone has poor film-forming ability, and the graphite film lacks durability during dry abrasion, as well as poor adhesion to mating materials.

The present invention eliminates the drawbacks of graphite alone and allows a uniform and highly adhesive graphite coating to be easily formed on steel materials. That is, by mixing fine graphite powder with fine powder of saturated dicarboxylic acid, the fine powder of saturated dicarboxylic acid softens and melts on the surface of the heated steel material, and the fine powder of graphite is coated.

A method for forming a graphite layer on the surface of a steel material is to uniformly disperse and suspend graphite and saturated dicarboxylic acid fine powder in water by adding a dispersion/suspension agent, and then heat the dispersion/suspension on the steel material. By spraying the saturated dicarboxylic acid fine powder onto and melting it, a coating film of graphite fine powder is formed.

The saturated dicarboxylic acid (H02C(CH
2) ncOzH) is propanediacid with n=1 n-32
A compound of tetratriacontanedioic acid is used,
Preferably, the range is from hexanedioic acid with n = 4 to hexadecanedioic acid with n-14. In particular, dodecanedioic acid with n = 1O is a petrochemical product synthesized using butadiene as the main raw material, and its features are: [F] High quality, unlike natural products such as n = 7 nonane dioic acid (azelaic acid) and n = 8 decane diacid (sepacic acid), ■ Solubility in water, vapor pressure Small size; ■ Resistant to cyclization and good thermal stability. Furthermore, the toxicity (LDso-71/kf or higher, rat) is very low, and its smoothness is preferred for practical purposes.

Dispersing/suspending agents necessary for uniformly dispersing/suspending fine powder of graphite and saturated dicarboxylic acid in water, or thickeners used as auxiliary agents for more effective suspension, etc.
Commonly used casein and animal gelatin,
Vegetable gum arabic, alginic acid, starch, dextrin, synthetic cellulose derivatives such as MC and CMC, polyvinylalconope polyacrylate, surfactants, and inorganic silica colloids, bentonite clay, etc. used for specific purposes.

The lubricant of the present invention is particularly effective for rolling and forging using a mandrel. That is, the present invention uses fine powders of graphite and saturated dicarboxylic acid as main ingredients, and the above-mentioned main ingredient and dispersing, suspending, thickening agents, etc. are mixed in a heated mandrel, and these mixtures are added to water. A lubricating coating is formed by suspending and spraying.

The proportion of dispersing/suspending agents, thickeners, etc. necessary for dispersing and suspending fine powder of graphite and saturated dicarboxylic acid in water is 20% by weight, but the appropriate amount is 0.
．． 5% to 10% is preferred.

The present invention will be explained below using Example 5.

Example 1 Graphite powder 75 with particle size 0.5-10μ, particle size 0.5μ-
50. The components of the lubricant consisting of 25% dodecane diacid powder in a were uniformly mixed in a dry state. Prior to use, this material was dispersed/suspended in water.

Water should be prepared using carboxymethyl cellulose (CMC) in advance.
)0.5% and polypropylene glycol (molecular weight 1o
oo)z% was added.

The amount of solids containing graphite and dodecane diacid relative to water is 2
It was set as 5. A mandrel parr was immersed in this suspension.

Water was evaporated on the surface of the mandrel par heated to 135° C., yielding a graphite coating containing dodecanedioic acid.

Example 2 Graphite powder with a particle size of 0.5 to 30μ 74.5μ, particle size 0.5
The components of a high temperature lubricant consisting of 23% dodecanedioic acid powder and 2.5 parts gum arabic, ~60μ, were uniformly mixed in the dry state. Disperse this in water before use.
suspended. The amount of solids relative to water was set at 20 parts. A mandrel parr was immersed in this suspension. Water evaporates on the surface of the mandrel heated to 150℃ and turns into dodecane? A graphite coated membrane containing acid was obtained.

Example 3 72% graphite powder with particle size 5-50μ, particle size 1°-60μ
24 times of decanedioic acid and carboxymethyl cellulose (
CMC) 2% was dry mixed.

These solids are used by suspending them in water. The ratio of solids to water was 23% of the total weight of the suspension. This lubricant mixture is sprayed onto the mandrel of a rolling mill used to process seamless steel pipes, and graphite powder containing decane diic acid adheres to the heated surface of the mandrel, creating a coating with excellent lubricity. A membrane was obtained.

Example 4 75% graphite powder with particle size 0.5-60μ, particle size 10-60
20% μ of nonane diacid and 5 g of gum arabic are used suspended in water containing colloidal silica (S!-020-02%). The amount of A' engraving relative to the suspension was 20 parts. This lubricant mixture is sprayed onto the mandrel of a rolling mill used to process seamless steel tubes. Graphite powder containing the above components adhered to the surface of the heated mandrel par, and a coating film suitable for high-temperature lubrication was obtained.

The hot working conditions for Examples 1 to 4 are as follows.

12 carbon steel pipes with an outer diameter of 60.5+nm and a wall thickness of 6.0 mm
When heated to 50 ° C. and rolled into a tube with an outer diameter of 53.0 wm and a wall thickness of 3.5 mm by a 4-stand mandless mill, the speed of the mandrel was maintained at 80% of the peripheral speed of the roll of the first stand, The thrust force acting on the mandrel was measured. The smaller this thrust is, the better the lubrication performance is. The measurement results are shown in the table below.

Results of using lubricant (Note) For conventional product A, a lubricant consisting of graphite powder and mineral oil emulsion was used as a comparative example.

Agent: Patent attorney: Hikaru Aki Sawamasa and 2 others

Claims (1)

[Claims] (A lubricant for hot forming of steel materials, in which a composition consisting of graphite powder, 1 to 50 weight percent hydrated dicarboxylic acid, and 20% by weight or less of a dispersing/suspending agent is suspended in water.