JPH07126682A - Lubricant for hot working - Google Patents

Abstract

(57) [Abstract] [Purpose] The present invention is to provide a steel material such as a thin plate, a steel pipe, a thick plate, a bar steel, and a wire rod (common steel, stainless steel, high alloy steel, etc.).
Related to the lubricant used during the hot working of
Provided is a lubricant for hot working, which is supplied to a contact surface of a work material such as a roll and a work material and enables favorable hot working such as seizure prevention. [Composition] A hot working lubricant comprising water and a solid lubricant, which is a third component which is insoluble in water and does not swell.
It is characterized in that a substance having a melting point and / or a softening point in the range of 00 ° C. or higher and 300 ° C. or lower is added and mixed, and preferably the third component adheres and / or coats the surface of the solid lubricant. It is a lubricant for hot working. More preferably, the hot working lubricant of the present invention has a viscosity of 500 c
By adjusting the temperature to be P (40 ° C.) or less, the spreadability is good, it can be firmly adhered to the processing tool, and seizure between the processing tool and the workpiece can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lubricant used during hot working of steel materials (plain steel, stainless steel, high alloy steel, etc.) such as thin plates, steel pipes, thick plates, steel bars and wires. The present invention relates to a hot-working lubricant which is supplied to a contact surface between a working tool such as a roll and a work material and enables good hot working.

[0002]

2. Description of the Related Art The main purpose of using a lubricant for hot working is to reduce the wear of working tools, reduce the power required for working, and prevent surface flaws on a work material due to seizure. In order to achieve such an object, conventionally, mineral oils, animal and vegetable oils, fats and oils, synthetic esters, etc. as a main component, to which extreme pressure additives, oiliness agents, emulsifiers, etc. have been added, and further to such lubricating oils Solid lubricants such as graphite, graphite, mica, carbon black, molybdenum disulfide, and iron oxide, and lubricants to which inorganic compounds such as potassium phosphate and boron nitride are added have been used (for example, JP-A-56). -8
6996, JP-A-58-13696, JP-A-63-254195, and JP-A-64-83309.
JP-A-3-10096, JP-A-3-91
596, etc.).

[0003]

Generally, the above-mentioned lubricant for hot working is diluted with water before use. That is,
Since hot working is generally performed at a high temperature of about 700 to 1000 ° C., it is necessary to cool the working tool,
Since the main components of lubricants such as mineral oils, animal and vegetable oils, fats and oils, and synthetic esters have the risk of smoke, ignition, explosion, etc., they should be diluted with water and used on the contact surface between the processing tool and the processed tool. Supplied. Therefore, the component of the lubricant actually supplied is small, and the amount of the lubricant present on the contact surface between the workpiece and the machining tool is not sufficient.

The above-mentioned objects such as reduction of wear of the machining tool and reduction of power required for machining can be achieved when a relatively small amount of the lubricating coating exists between the machining tool and the workpiece. Are known. However, in order to prevent surface scratches on the work piece caused by seizure, it is necessary to completely prevent direct contact between the work tool and the work material, which is the starting point of seizure, and the lubricating film is not It is necessary that the whole area of the contact surface of the processed material is sufficiently present.
For this reason, conventional lubricants reduce the wear of machining tools,
Although it is effective in reducing the power required for processing, it has not been sufficiently effective in preventing surface defects of the work material.

It is becoming more and more important in recent years to prevent flaws on the surface of a work material as steel grades become higher grade. To solve this problem, grease, water-soluble polymer, etc. are added to a lubricant. A method has been proposed in which the viscosity is increased and the amount of the lubricant (remaining amount) attached to the surface of the processing tool is increased (for example, JP-A-58-47095 and JP-A-59-1).
05095, etc.). However, if the viscosity of the lubricant increases, it is necessary to increase the injection pressure in order to maintain the supply amount, or the spreadability of the lubricant decreases and the area of the work tool that can be supplied decreases. It became difficult to supply the agent to the entire surface of the processing tool, a solid lubricating film could not be formed on the entire contact surface, and seizure could not be completely prevented.

[0006] Generally, as one of the methods for adhering solids to each other, there is known a method in which a semi-molten state is once set and then solidification is performed to perform stronger adhesion. Using this principle, a method of adhering a solid lubricant and a working tool with a substance capable of being in a semi-molten state has already been proposed (for example, JP-A-2-263898, JP-A-3-115398, etc.). ). However, these proposals are based on the assumption that a solid substance is added to oil or that it is used as a solid substance alone.Since there is a risk of smoke, ignition, explosion, etc. in oil, solid lubricants can be used as existing lubricants. Since it cannot be applied to a supply device, even if the amount of adhesion is increased, it has not been possible to prevent seizure.

From this point of view, there has been a strong demand for a technique which has a low viscosity and can supply a sufficient amount of lubricant to the contact surface between the workpiece and the machining tool.

[0008]

Means and Actions for Solving the Problems The present inventors have
Since substances having a melting point and / or a softening point are in a semi-molten state in the vicinity of a melting or softening temperature, attention is paid to an increase in the adhesive force with a solid surface, and these substances are treated with water,
It was found that the addition of a third component to a lubricant composed of a solid lubricant improves the adhesion between the solid lubricant and the solid surface, and the present invention was devised based on this finding. Furthermore, by selecting a substance that is insoluble in water and does not swell as a substance to be added, it is possible to supply the lubricant to the entire surface of the machining tool without increasing the viscosity of the lubricant and without increasing the injection pressure. Made possible As a result, it was found that a stable solid lubricating film can be formed on the contact surface and seizure can be completely prevented, and the present invention has been completed based on this finding.

The hot-working lubricant of the present invention comprises three components: water, a solid lubricant, and a substance which is insoluble in water and does not swell and has a melting point and / or a softening point of 100 ° C. or higher and 300 ° C. or lower. , And these are added and mixed. Since the main component of the hot working lubricant of the present invention is water, unlike the case of the lubricating oil, there is no risk of ignition, ignition, explosion, etc., and it should be used for cooling the working tool. Also, since it can be supplied to the processing tool at a concentration of 100% without being diluted, the lubricating film can be made to sufficiently exist over the entire contact surface.

The solid lubricant used in the hot-working lubricant of the present invention includes all substances having lubricity at the temperature during hot working, such as graphite, carbon black, boron nitride, molybdenum disulfide, Refers to talc, mica, phosphate, etc. The third added in the lubricant for hot working of the present invention
The component acts as an adhesive that firmly adheres the solid lubricant to the surface of the working tool. This utilizes the fact that in order to adhere the above-mentioned solids to each other, once they are in a semi-molten state, they are firmly adhered.

That is, the following is presumed as the mechanism of adhesion. When the lubricant for hot working of the present invention is supplied to the surface of the working tool, if the third component has a melting point and / or a softening point lower than the surface temperature of the working tool, it can be in a semi-molten state. Since this semi-molten state is presumed to be close to a high-viscosity liquid, it is possible to adhere more strongly to the working tool than the solid state. Further, since the third component is attached to the solid lubricant in advance, the solid lubricant is also attached and fixed on the surface of the working tool. If the third component is insoluble in water, the solid lubricant can reach the contact surface between the work material and the working tool while being attached to the working tool,
Exhibits a lubricating effect.

Therefore, the features of the lubricant for hot working of the present invention are that the third component to be added is insoluble in water and does not swell, and the melting point and // Alternatively, the softening point is defined. One of the properties required for the third component of the hot working lubricant of the present invention is that it is insoluble in water and does not swell. As mentioned above, normally, in hot working, the surface of the processing tool is cooled by water, so what is soluble in water is
This is because even if it adheres to the processing tool, it cannot easily adhere to the processing tool because it easily flows down by the cooling water.

Further, since the hot-working lubricant of the present invention contains water as a constituent component, a substance soluble or swelling in water increases the viscosity of the lubricant. Therefore, it becomes difficult to uniformly supply the lubricant to the entire surface of the working tool, which is not desirable. Therefore, the third component added to the hot-working lubricant of the present invention must have the property of being insoluble in water and not swelling.

Another necessary property of the third component of the hot working lubricant of the present invention is that the melting point and / or the softening point is 100 ° C. or higher and 300 ° C. or lower. As mentioned above, since the processing tool is cooled, the hot working is 70
Despite being performed at a high temperature of 0 to 1000 ° C,
Immediately after the lubricant is supplied, the actual temperature in the vicinity of the extreme surface of the working tool is considerably low.

Therefore, in order to ensure that the third component can be in a semi-molten state, it is desirable that the melting point and / or the softening point be below this temperature. However, since the hot-working lubricant of the present invention contains water as a main constituent component, if the melting point and / or the softening point of the third component is lower than 100 ° C., it will be in the nozzle or pipe before being supplied to the working tool. It is melted by radiant heat from a processing tool. This is not preferable because it increases the viscosity of the hot working lubricant of the present invention. Therefore, it is necessary to have a melting point and / or a softening point of 100 ° C. or higher in order to uniformly attach the lubricant to the surface of the processing tool without increasing the viscosity.

On the other hand, if the melting point and / or the softening point of the third component is too high, the semi-molten state is not easily obtained at the surface temperature of the working tool, so that the adhesive force to the surface of the working tool is not exhibited. As described above, since the working tool is cooled, the surface temperature of the working tool is about 500 ° C. or lower. Therefore, it is desirable to have a melting point and / or softening point below the temperature of the working tool surface.

Further, if the above substances remain on the surface of the processing tool after processing, the material itself may be a factor for surface flaws on the material to be processed, so that the third component can be easily removed or burned off after processing. The material that does not remain on the surface of the machining tool is
Because substances that decompose thermally are better than substances that are thermally stable, 3
A substance having a melting point and / or a softening point below 00 ° C. is preferable.

Therefore, the third component of the hot-working lubricant of the present invention is a substance that is insoluble in water and does not swell, has a melting point and / or a softening point, and has a temperature of 100 ° C. or higher and 300 ° C. or lower. It must be a substance within range. In addition, as a third component, coating on a solid lubricant and / or
Alternatively, a substance that can be easily attached is desirable, and a substance that is soluble in some liquid may be used because the coating can be performed relatively easily. This is necessary in order to firmly and reliably attach the solid lubricant to the surface of the working tool.

Any resin may be used as long as it has the above characteristics. For example, polyethylene resin, polystyrene resin, polypropylene resin, nylon resin, vinylidene resin, ABS resin, styrene resin, PBT resin, PET resin. , Organic resins such as coumarone resin are priced,
From the viewpoint of general purpose, it is desirable as the third component of the lubricant for hot working of the present invention.

The addition amount of the solid lubricant and the third component in the hot working lubricant of the present invention is such that the above-mentioned spreadability of the lubricant is secured, fluidity is secured in the pipe or nozzle or in the working process, and the lubricating effect is obtained. It is decided in consideration of securing of. The viscosity of the lubricant at 40 ° C. is 500 because it needs to be usable in the existing lubricant supply device.
It is preferably cP or less.

However, when the amount of the solid lubricant added is less than 5% by weight, the lubricant has a low viscosity of 500 cP (40 ° C.) or less, but a sufficient lubricating film cannot be formed, so that the lubricating effect and seizure resistance are not achieved. Can't get On the other hand, if the addition amount of the solid lubricant exceeds 30% by weight, the lubricant is 500 cP (40
(° C) or higher and the spreadability and fluidity cannot be secured. Therefore, the amount of the solid lubricant added to the hot working lubricant of the present invention is preferably 5% by weight or more and 30% by weight or less.

In the hot working lubricant of the present invention, the third component must be adhered and / or coated on the surface of the solid lubricant in order to more firmly adhere the machining tool and the solid lubricant. Is desirable. Therefore, the addition amount of the third component of the lubricant for hot working of the present invention can be expressed as a weight ratio of the third component / solid lubricant. The viscosity of the hot working lubricant of the present invention is the above-mentioned value, that is, 500.
In order to be cP (40 ° C.) or lower, the weight ratio of the third component / solid lubricant may be in the range of 5/95 to 70/30, preferably 10/90 to 60/40. is there.

In the lubricant for hot working of the present invention, the solid lubricant and the third component can be attached and / or coated by the following method. That is, the third component is dissolved in a solvent and mixed with a solid lubricant, stirred and uniformly dispersed, and then dried to remove the solvent. After the third component is heated and dissolved, a solid lubricant is added. And stirring to uniformly disperse. The lubricant for hot working of the present invention can be prepared by pulverizing the mixture obtained by any of the above methods and then dispersing it in water.

As described above, the third water-insoluble and non-swelling third
The components and solid lubricants can supply the lubricant to the entire surface of the processing tool without increasing the viscosity of the lubricant, but if the particle size is large, when supplying the lubricant for hot working, the lubricant inside the pipe or nozzle Since it causes troubles such as clogging in the processing process, it is necessary to use a particle diameter smaller than the tip diameter of the pipe or nozzle, and the average particle diameter is 1
It is desirable that it is less than or equal to mm. Further, if the particle size is too small, the surface energy of the particles becomes large, which makes it difficult to uniformly disperse the particles in the dispersion medium, and also causes the viscosity of the lubricant to increase. Since seizure cannot be completely prevented in such a non-uniform dispersion state, the average particle size must be 1 μm or more in order to ensure uniform dispersibility.

Examples of the method for adjusting the particle size include mechanical crushing methods such as a Henschel mixer, a vibrating ball mill, a universal mill, etc. It can exhibit its properties as a hot working lubricant. Furthermore, when uniformly dispersed in water, previously known additive components such as coating film stabilizers, antioxidants, surfactants, thickeners, defoamers, rust inhibitors, emulsifiers, extreme pressure agents are previously prepared. An additive such as a corrosion inhibitor may be added.

The softening point as referred to in the present invention is the temperature at which the third component of the present invention becomes practically deformed with increasing temperature and cannot withstand external force. The deflection temperature and the Vicat softening temperature. It means the temperature indicated by etc.

[0027]

【Example】

Example 1 Table 1 shows components of Examples of the hot working lubricant of the present invention. Table 2 shows the composition of the solid lubricant used as a comparative example. In Tables 1 and 2, the unit of numerical values showing the composition is% by weight. The coating treatment was carried out in both Examples and Comparative Examples.
After the solid lubricant and the adhesive were mixed in advance, heat treatment was performed at a temperature 50 ° C. higher than the melting point and / or the softening point for 20 minutes. After the coating treatment, pulverization treatment was carried out until the particle diameter became 100 μm or less, and this was added to water to prepare a lubricant.

The adhesion test was conducted as follows. 400
Steel plate heated to ℃ or above (SUS304, 30x30x
0.01mm), injection pressure 4k from a distance of 20cm
The lubricant was sprayed for 10 seconds at a flow rate of 3 ml / ^second at gf / cm ² . Then, the steel plate was dried at 100 ° C. for 1 hour, the weight was measured, and the value obtained by subtracting the weight before the adhesion test from this weight was divided by the steel plate area to determine the adhesion amount (g / cm ² ).
And

The evaluation results are shown in Table 3. From these results, it can be seen that the solid lubricant adhesion of the lubricant of the comparative example is much higher than the solid lubricant adhesion of the example of the example in which the melting point and / or the softening point of 100 ° C. to 300 ° C. is coated. It turns out that the quantity is low. Example 2 Using a two-cylindrical hot rolling sliding friction tester, Example 1
The anti-seizure property of the lubricant having the same composition as the above was evaluated. The test piece has an outer diameter of 80 mm and a thickness of 10 mm. The mating piece has an outer diameter of 165 mm and a thickness of 15 mm. SKD61 was used for the test piece, and high chromium cast iron was used for the mating piece.

The test conditions were 850 ° C. for the mating piece and 5 for the test piece.
The test piece was heated to 00 ° C., the speed of the test piece was 500 rpm, the speed difference between the mating piece and the test piece was 10% of the speed of the test piece, and the lubricant was sprayed onto the test piece at 5 ml / sec. At the same time, a load of 70 kgf was applied to cause friction while blowing cooling water at the same flow rate, and the amount of wear of the test piece was measured. As a comparative example, a lubricant having the same composition as in Example 1 was used. Its composition is the same as in Table 2.

The results are shown in Table 4. A weight of 10 mg or less or no change before and after the test indicates that there is no wear or seizure, and the weight increase after the test is 100 mg.
In the above cases, seizure causes adhesion with the mating material and the mating material adheres (transfers). From these results, it can be seen that the lubricants of Examples are superior in wear resistance and seizure resistance to the lubricants of Comparative Examples.

[0032]

[Table 1]

[0033]

[Table 2]

[0034]

[Table 3]

[0035]

[Table 4]

[0036]

By using the lubricant for hot working of the present invention, seizure between the working tool and the work material can be reduced, and as a result, the occurrence of surface flaws on the work material can be prevented, It has the effect of improving productivity.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location C10M 143: 10 145: 22 149: 14 125: 24) C10N 20:00 A 20:02 30:08 40:24 Z 50:08 (72) Inventor Fueyasu Yamamoto 20-1 Shintomi, Futtsu City, Chiba Nippon Steel Corporation Corporate Technology Development Division

Claims (3)

[Claims] 1. A lubricant for hot working comprising water and a solid lubricant, which is a substance which is insoluble in water and does not swell as a third component,
Further, a lubricant for hot working, wherein a substance having a melting point and / or a softening point in the range of 100 ° C. or higher and 300 ° C. or lower is added and mixed. 2. The third component is adhered and / or coated on the surface of a solid lubricant.
The hot working lubricant described. 3. The lubricant for hot working according to claim 1, which has a viscosity at 40 ° C. of 500 cP or less.