JP2586280B2 - Lubrication method for hot rolled material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of lubricating a rolled material in hot rolling such as inclined piercing rolling, and more particularly to a method of lubricating a liquid lubricant containing a powdered lubricant.

[0002]

2. Description of the Related Art As a method of lubricating a rolled material in hot rolling such as inclined piercing rolling, there is a method of directly applying a liquid lubricant to the surface of a material to be rolled at a high temperature immediately before rolling (Japanese Patent Application Laid-Open No. 60-1985).
184410). The liquid lubricant used here is, for example, a metal oxide-water glass type lubricant in which a metal oxide powder is mixed with water glass as a main lubricant and made into an aqueous solution state. Then, it is fixed to the surface of the material to be rolled by a sintering reaction and a melting reaction by reacting with the surface of the material to be rolled at a high temperature. The rolled material coated with the lubricant is immediately subjected to rolling.

[0003]

In the lubrication of a hot-rolled material in which a liquid lubricant containing such a powdery lubricant is applied to the surface to be rolled immediately before rolling, when the material to be rolled undergoes rolling, It is necessary that a sufficient amount of lubricant is held on the surface with sufficient adhesion. However, in the conventional method,
Despite the excellent adhesion of the lubricant itself, the adhesion was not sufficiently exhibited, and there was a possibility that the amount of adhesion and the adhesion would be insufficient.

For example, the application of a lubricant immediately before rolling is generally performed by air spraying, as disclosed in Japanese Patent Application Laid-Open No. Sho 60-184410. However, the lubricant applied by air spray has a diameter of 0.01-
It becomes a 4.0 mm droplet shape, and the coating density per unit area is not sufficiently ensured. In addition, depending on the condition of the nozzle, it often becomes locally dense and non-uniform adhesion distribution.

If the material to be rolled is subjected to rolling immediately after the application of the lubricant, the lubricant cannot sufficiently complete a melting reaction, a sintering reaction, and a reaction with the surface scale. The agent is not stable on the surface of the material to be rolled. as a result,
In particular, when rolling conditions such as large working ratio, large sliding friction speed, and large surface pressure are severe such as rolling for high alloys such as stainless steel and Ni-based alloy containing a large amount of alloy components such as Cr and Ni, lubrication performance is required. Are not sufficiently exhibited, and seizure flaws are easily generated.

An object of the present invention is to provide a method of lubricating a hot-rolled material which can stably fix a sufficient amount of a liquid lubricant containing a powdered lubricating agent to the surface of a material to be rolled. .

[0007]

According to the lubrication method of a hot-rolled material of the present invention, a liquid lubricant containing a powdered lubricant is applied to the surface of a material to be rolled immediately after entering a rolling mill. The method is characterized in that the applied lubricant is homogenized by rubbing the surface of the rolled material lightly, and then left for at least 10 seconds and not more than 60 seconds after the treatment before rolling by the rolling mill.

[0008]

In the lubricating method for hot-rolled material of the present invention, a lubricant is applied to the surface of the material to be rolled at a high temperature on the entry side of the rolling mill.
The material to which the lubricant has been applied is subjected to light pressure rubbing immediately after application to make the lubricant uniform, and then left for 10 to 60 seconds in order to secure the adhesion reaction time of the lubricant, and then subjected to rolling. Is done.

Regarding the rolling mill, regardless of the type, for example, a two-roll piercer of an inclined roll type, a two-roll elongator,
A rolling machine such as a roll elongator, an assell mill, a plug mill, a mandrel, a reducer or the like, a mold steel rolling machine such as a universal mill, and a plate rolling machine such as a hot strip mill can be used.

The lubricant is a liquid lubricant containing a powdered lubricant. The main lubricating agent is not particularly limited in its type, and general graphite powder can be used as a hot rolling lubricant.Metal oxide powder, mica, mica, etc., which does not have the danger of carburizing, are preferably used. Recommended. Examples of the metal oxide include alumina (Al ₂ O ₃ ), silica (SiO ₂ silicate), iron oxide (Fe ₂ O ₃ or Fe ₃ O ₄ ), and chromium oxide (Cr ₂ O ₃ ). . The amount of the lubricating agent is desirably 10 to 60% by weight, and the particle size is desirably 2 mm or less.

Water glass is usually used as a binder for making the main lubricant into a liquid state. The amount of water glass is desirably 10 to 50% by weight expressed as the amount of sodium silicate as a solid content, and the amount of water is 200 to 5% expressed as viscosity.
000 cp is desirable. In addition to the lubricating agent, a dispersant and a thickener can be added as needed. As a method for applying the lubricant, air spray is desirable.

When such a lubricant is spray-coated on the surface of the material to be rolled, as described above, the applied area becomes non-uniform and the sprayed droplet has a diameter of 0.01 to 4.0 mm.
And the dispersion of the adhesion area distribution are also large. In order to make this state uniform, in the method of the present invention, the surface of the material to be rolled immediately after the application of the lubricant is lightly rubbed.

Light pressure rubbing refers to rubbing the surface of a material to be rolled while lightly reducing it with a heat-resistant roller or brush. For example, the material is sandwiched between heat-resistant skew rollers provided on the entry side of a rolling mill. There is a method of carrying.

More specifically, for example, when the method of the present invention is applied to the external lubrication for an elongator in a Mannesmann type seamless pipe production line, the material to be rolled is rotated at the outlet side of the piercer, which is the preceding step. The lubricant is spray-coated on the outer surface of the material to be rolled during rolling, and then the inscribed circle diameter of the roller and the The clearance with the outer diameter of the material is made smaller than usual, and light rolling is performed. As a result, the outer surface of the material to be rolled immediately after the application of the lubricant is lightly rubbed, and the lubricant is homogenized.

Here, if the rubbing is carried out by rolling with a high degree of working, the rolling itself consumes a lubricant, and seizure flaws are easily generated by the rolling tool. Further, if the material to be rolled immediately after the application of the lubricant is simply transferred on the conveyor, the applied lubricant tends to be separated from the surface of the material to be rolled by sliding. Light rubbing makes the lubricant uniform without such concerns.

As a condition of the light rubbing, assuming that the deformation resistance of the material to be rolled at the time of the light rubbing is kf, the rolling pressure is reduced so that the surface pressure acting on the surface of the material to be rolled becomes 0.6 kf to 1.1 kf. It is desirable to do. That is, if the surface pressure is less than 0.6 kf, the effect of uniformizing the applied lubricant on the surface of the material to be rolled cannot be obtained, and if the surface pressure exceeds 1.1 kf, the light pressure jig itself is seized. The surface pressure of 1.1 k is taken as an example in the case of a SUS316 steel hollow rolled material (temperature 1180 ° C.).
When f is expressed in terms of the diameter reduction ratio, it is about 0.2%.

[0017] Immediately after the application means before the lubricant applied to the surface of the material to be rolled starts a fixing reaction such as sintering, and is desirably within 10 seconds after the application.

The lubricant applied to the surface of the material to be rolled and subjected to the homogenization treatment usually has its binder sintered and melted, and further reacts with the scale on the surface of the material to be fixed on the surface of the material to be rolled. However, if the material to be rolled is subjected to rolling immediately after the homogenization treatment, the lubricant undergoes severe processing of rolling and falls off before the fixing reaction sufficiently proceeds. Therefore, in the method of the present invention, 10 minutes are required between the homogenization treatment by light rubbing and the rolling.
A leaving time of at least 60 seconds but not more than 60 seconds is secured for the fixing reaction.

In the rolling line, it is difficult to perform temperature control such as raising the temperature of the material to be rolled in order to assist the sintering reaction and the melting reaction of the lubricant, and the method of the present invention controls the time. .

In order to advance the sintering reaction and the melting reaction of the lubricant, it is necessary to conduct heat from the material to be rolled to the lubricant applied on the surface thereof. The thermal conductivity of the metal to be rolled is, for example, 0.1 to 0.2 cal / cm.deg. For iron, but the thermal conductivity of inorganic materials such as oxide scale on the surface of the material to be rolled and the main lubricant such as metal oxides in the lubricant. The thermal conductivity of the compound is extremely higher than that of the metal, for example, 0.001 to 0.003 cal / cm · deg for iron oxide. Therefore, it takes a considerable time for the lubricant to be heated to the temperature required for the reaction, and when the reaction time is taken into consideration, a standing time of 10 seconds or more is required from the light rubbing to the start of rolling.

That is, if the standing time is less than 10 seconds, the sintering reaction and the melting reaction of the uniform lubricant on the material to be rolled are insufficient, and the lubricant is not sufficiently stabilized. However, 60
If left for more than a second, the temperature of the material to be rolled will be too low, impairing the workability of rolling and, at the same time, seizure flaws will be more likely to occur due to an increase in deformation resistance. Further, when the material to be rolled is ordinary steel, the applied lubricant easily peels off along with the scale generated on the surface of the material to be rolled, and the productivity is reduced. Therefore, 60 seconds is set as the upper limit of the leaving time.

[0022]

Embodiments of the present invention will be described below.

The effectiveness of the present invention was investigated by taking, as an example, the rolling on an inclined roll type stretching machine of a Mannesmann-Plug Mill tube line, that is, an elongator.

FIG. 1 shows the arrangement of devices in the vicinity of the elongator. The material to be rolled 1 is pierced and rolled by the piercer 2 and then transferred to the elongator 3 for elongation rolling. The material that advances while rotating from the piercer 2 is restrained from the outer surface side by three rollers of a three-roller shell steer at the piercer outlet, and the run-out is suppressed. The material that has escaped from the piercer 2 passes through the inside of the ring-shaped nozzle, enters the elongator 3, and starts rotating again. Elongator 3
The material entering while rotating is held by the guide shoe at the entrance of the elongator body.

In the present embodiment, a lubricant was applied to the outer surface of the material supplied to the elongator 3, and the lubricity was examined based on the occurrence of seizure flaws at the guide shoe at the entrance of the elongator.

The material to be rolled is made of SUS316 austenitic stainless steel.
mm, thickness 20 mm, length 6000 mm, and after stretching and rolling, the outer diameter is 278 mm and the thickness is 9 mm, and the stretching ratio is 1.83.
It is. The outer surface temperature of the material to be rolled was 1160 immediately after piercing and rolling.
１1180 ° C. The material of the guide shoe is 36
It is a high alloy of wt% Cr-33wt% Ni.

The lubricant is an iron oxide-water glass type lubricant having a viscosity of 2,000 cp with iron oxide 40% by weight-sodium silicate 40% by weight, and alumina 40% by weight-sodium silicate 4
Alumina-water glass-based lubricant having a viscosity of 2000 cp and 0% by weight was used, and both were applied to the outer surface of the material before elongation rolling by air spray.

The lubricant was applied at the piercer outlet A, during transfer B, or at the elongator inlet C. In A, when the material to be rolled is rotating during piercer rolling, in B, when the material to be rolled passes through the ring-shaped nozzle during transfer, and in C, when the material to be rolled is rotating at the elongator inlet, lubrication is performed. The agent was applied. The time from the perforation of the material to be rolled to the application is 0.5 seconds, 6.0 seconds, and 12.5 seconds for A, B, and C, respectively. The homogenization treatment was performed only on the shell steadia at the outlet of the piercer, and the rolling force was adjusted by changing the clearance between the inscribed circle diameter of the three rollers of the shell steadia and the outer diameter of the material to be rolled. The time from the application of the lubricant to the homogenization treatment is 0.5 seconds.

The lubricating property is evaluated by the result of visual inspection of the outer surface of the product which has been rolled to the sizer and further pickled after the solution treatment, and is rejected when there is a flaw having a flaw depth of 0.05 mm or more. , Flaw occurrence rate of 20% or more x, 10% or less ○, 10
% Was exceeded and less than 20%.

Table 1 shows the results of an investigation using an iron oxide-water glass based lubricant under 24 conditions. Under some conditions, the material to be rolled (hollow shell) after the application of the lubricant and the homogenization treatment and before rolling out is dispensed, and one or more rolls of one or more are removed.
A sample of 00 mm × 100 mm was cut out, and the adhesion area ratio of the lubricant was examined by microscopic observation or the like.

Nos. 1 to 14 are points A, Nos. 15 to 20 are points B, and Nos. 21 to 24 are lubricants applied at point C.

In Nos. 1 to 5, 8, 13, and 14, a lubricant was applied at point A, and a uniform treatment was performed with a roller using shell steady media. The clearance (gap) with the outer diameter of the hollow shell was changed. The smaller the clearance, the smaller the material to be rolled, such as Nos. 13 and 14, in which the rolled material is completely constrained by rollers, the fewer the seizure flaws.

In Nos. 6 to 12, the time until the material to be rolled after the coating and homogenization treatment was rolled, that is, the time for the lubricant to undergo a sticking reaction on the outer surface of the material to be rolled was changed. In the case of No. 6 which is short, the reaction is insufficient and the adhesion is reduced, and the generation of flaws is not suppressed. If the reaction time is too long, as in No. 12, the temperature of the material to be rolled decreases (down to 1050 ° C before elongation rolling).
This increases seizure flaws.

In the case of Nos. 15 to 20 B, the reaction time was only changed because the equipment was difficult to homogenize.
As in the case of A, there is a significant difference with time, but the incidence of flaws is high.

In the case of C of Nos. 21 to 24, too, the reaction time was only changed because the equipment was difficult to achieve a uniform treatment.
As in the case of A, there is a significant difference with time, but the incidence of flaws is high.

Table 2 shows the results of an investigation using an alumina-water glass-based lubricant under the same conditions under 24 conditions. No.
Nos. 31-44 are point A, Nos. 45-50 are point B, No. 5
Reference numerals 1 to 54 indicate the application of the lubricant at the point C.

In Nos. 31 to 35, 38, 43 and 44, a lubricant was applied at point A, and the roller was homogenized by shell stedia. The clearance (gap) with the outer diameter of the hollow shell is changed. In this case as well, the smaller the clearance, and the more the rolled material is completely constrained by rollers as in Nos. 43 and 44, the smaller the seizure flaws.

In Nos. 36 to 42, the time until the material to be rolled after the coating and homogenizing treatment is rolled, that is, the time during which the lubricant proceeds with the sticking reaction on the outer surface of the material to be rolled to stabilize the adhesion is changed. Was. In the case of No. 36, which has a short time, the reaction is insufficient and the adhesion is reduced, and the generation of flaws is not suppressed. If the reaction time is too long as in No. 42, seizure flaws are returned and increased due to a decrease in the temperature of the material to be rolled (down to 1040 ° C. before elongation rolling).

In the case of Nos. 45 to 50, the reaction time was only changed because the homogenization treatment was difficult on equipment. As in the case of A, there is a significant difference with time, but the incidence of flaws is high.

In the case of Nos. 51 to 54, too, the reaction time was only changed because the homogenization treatment was difficult on equipment. As in the case of A, there is a significant difference with time, but the incidence of flaws is high.

[0041]

[Table 1]

[0042]

[Table 2]

[0043]

As is apparent from the above description, the method for lubricating a hot-rolled material according to the present invention allows a liquid lubricant containing a powdered lubricant to be uniformly and stably fixed to the surface of a material to be rolled. Enables advanced lubrication utilizing the performance of lubricants.

[Brief description of the drawings]

FIG. 1 is a layout diagram of a piercer to an elongator showing a lubricant application position.

[Explanation of symbols]

 1 rolled material 2 piercer 3 elongator

Claims (1)

(57) [Claims] 1. A liquid lubricant containing a powdered lubricant is
Immediately after applying to the surface of the material to be rolled on the entry side of the rolling mill, the surface of the material to be rolled is lightly rubbed to uniformize the applied lubricant, and then left for 10 seconds or more and 60 seconds or less after the treatment. And then performing rolling by the rolling mill.