JP3286159B2 - Hot lubrication rolling method - 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 for rolling and lubricating steel materials (such as ordinary steel, extremely low carbon steel, and stainless steel) such as thin plates, thick plates, strips, and steel pipes. More particularly, the present invention relates to a hot rolling lubrication method for preventing surface damage such as wear and seizure while securing a frictional force.

[0002]

2. Description of the Related Art The purpose of using a lubricant during rolling is mainly to reduce wear and seizure generated on a friction surface between a roll and a steel material to be processed. Wear progresses due to microdestruction of the surface (ablation, plowing, etc.) due to the shearing force at the friction interface. If the lubricating film is partially formed on the friction interface, the wear is reduced.
Therefore, a lubricant for hot rolling is required to have a function of reducing frictional shear force acting on the surface of a material to be rubbed. It is generally said that seizure occurs when a hot steel material is subjected to plastic working and a new surface generated by an increase in surface area comes into contact with a roll to cause metal adhesion. In addition, in the case of metals that are difficult to oxidize, such as stainless steel, the scale layer on the surface is thin, so even in light-load processing where the amount of new surface generation is small, the scale layer is removed and the material and the roll adhere to the metal and seize. Leads to. Therefore, the hot rolling lubricant is also required to have a function of preventing the roll from contacting the new surface or the material.

Conventionally, as a lubricant for hot rolling used for such purpose, Toshio Sakurai, "Physical Chemistry of Lubrication"
And JP-A-63-309590 describe liquid lubricants in which one or more kinds of mineral oil, synthetic esters, extreme pressure additives and the like are mixed, and grease. Also, JP-A-63-230796 and JP-A-6-230796
In JP-A-3-254195 and the like, a powdery solid lubricant such as graphite, silicate, BN, iron oxide, molybdenum disulfide, or the like is added to a liquid lubricant such as the mineral oil or the synthetic ester, and grease. It is disclosed to use a mixture. In addition to liquid lubricants and greases, JP-A-55-161897 discloses a hot lubricant obtained by mixing a solid lubricant such as graphite with a molten inorganic material such as silicate. On the other hand, JP-A-04-372692 discloses a method in which wax or the like is directly applied to a rolling tool.

[0004] In order to perform stable production, it is necessary to maintain a stable biting property (frictional force) between a roll and a rolled steel material. Therefore, it is necessary to perform rolling while maintaining a certain level of the coefficient of friction at the interface between the roll and the rolled steel material during biting or rolling. If the conventional lubricant is sprayed directly onto the friction surface or roll surface, the friction coefficient will decrease and stable production cannot be achieved. To minimize the wear and prevent roll wear and seizure.

Further, as a method of suppressing slip from the viewpoint of a method of supplying a lubricant for hot rolling, supply of a lubricant is started after a material has been bitten into a roll of a rolling mill, and a friction coefficient at the time of biting is started. To prevent slippage by setting the friction coefficient to that of a non-lubricated state, stopping the supply of lubricant before the material exits the rolling mill, and burning the lubricant adhering to the roll surface by the heat of the material, thereby cleaning the roll surface. Rolling is performed in a non-lubricated state so that slippage does not occur when the next material bites.

[0006]

However, when a conventional lubricant is used, a mixture of water and a small amount of lubricating oil must be supplied over the entire surface of the roll in order to prevent slippage and maintain biting properties. And the required lubricating effect of the lubricating oil cannot be sufficiently obtained. If the concentration of the lubricating oil in water is increased to increase the effect of the lubricant, or if the supply amount of the lubricant mixed with water is increased, slip occurs. On the other hand, since a lubricant having a high coefficient of friction as disclosed in JP-A-6-184586 is expensive, it can be used only for rolling special steel having a high unit price in order to obtain an economic effect. . Therefore, in order to apply an ordinary lubricant to inexpensive steel materials such as ordinary steel and to obtain the effect of preventing wear and seizure by the lubricant, it is necessary to supply a sufficient amount of the lubricant necessary for obtaining the lubricating effect. In addition, a hot rolling lubrication method capable of simultaneously controlling the coefficient of friction is required.

The present invention proposes a hot lubricating rolling method capable of reducing roll abrasion and seizure without generating slip during rolling or slip during biting.

[0008]

SUMMARY OF THE INVENTION According to the present invention, there is provided a lubricating oil supply area in which a lubricating oil is supplied by separately providing a lubricating oil supplying area and a non-lubricating oil supplying area in a work roll surface in the axial direction of the work roll. In this method, roll wear or seizure is reduced by a lubricant, and the grip force required for rolling, that is, the biting property, is secured without supplying a lubricant. That is, in the method of hot-rolling a metal material using a work roll, a lubrication supply area for supplying a lubricant to the surface of the rolled work roll and a non-lubrication non-supply area for not supplying the lubricant are arranged in the roll axis direction. Alternately provided for lubrication
The lubricant is supplied while changing the arrangement of the supply region and the non-lubrication region . Preferably, the lubrication supply region and the lubrication non-supply region follow Formula (1). Also. Preferably, the lubrication supply area and the non-lubrication supply area are provided symmetrically with respect to the roll center .

ΣW ₀ ≦ ΣW ₁ (1) W ₀ : Length (width) of the lubrication supply area 3 in the roll axis direction W ₁ : Roll axis of the lubrication non-supply area 4 Direction length (width) 長 W ₀ : Total length in the roll axis direction of lubrication supply area 3 (total width) ΣW ₁ : Total length of lubrication non-supply area 4 in the roll axis direction (total width)

[0010]

FIG. 1 is an axial front view of a roll showing an embodiment of the present invention. When supplying lubricant,
The lubricant is supplied by being divided into a lubricant supply area 3 for supplying the lubricant and a non-lubrication non-supply area 4 not supplying the lubricant. The division of the lubricant supply area and the non-supply area is performed in the axial direction of the roll 1. A plurality of them are provided alternately. Also, in order to equalize the frictional force on the left and right so that snaking does not occur,
It is preferable to divide the lubrication supply area 3 and the non-lubrication supply area 4 symmetrically with respect to the roll center 2 (a plate center is also possible). The respective widths of the lubrication supply region and the non-lubrication supply region, that is, the lengths W ₀ and W ₁ in the roll axis direction may be determined according to the necessity of the precision in controlling the lubricity and the grip force. When an arbitrary line is drawn on the roll surface in the axial direction of the roll in order to secure the necessary frictional force, the total length of the line passing through the lubrication supply area and the total length passing through the non-lubrication area is expressed by the following equation. It is preferable to provide a lubrication supply area and a non-supply area as defined in (1).

ΣW ₀ ≦ ΣW ₁ (1) W ₀ : Length (width) of the lubrication supply area 3 in the roll axis direction W ₁ : Roll axis of the lubrication non-supply area 4 Length in the direction (width) ΣW ₀ : Total length in the roll axis direction of lubrication supply area 3 (total width) ΣW ₁ : Total length in the roll axis direction of non-lubrication supply area 4 (total width) In equation (1) When the area where the lubricant is actually supplied is larger than the specified lubrication supply area, the frictional force is reduced and stable rolling becomes difficult. The individual region section lengths may be different from each other. It is preferable that the divided area is divided in accordance with the formula (1) and the method of left-right symmetry, but the entire roll surface may be divided, but the lubrication is also supplied to a portion not covered by the plate. It is not economical to do.

As shown in FIG. 2, the method of supplying the lubricant divided into regions is provided in such a manner that a lubricant supply unit 5 divided in the roll axis direction is provided in parallel with the roll, and the lubricant supply unit is supplied from this unit to the roll. The lubricant is supplied only from the division unit corresponding to the zone 3. In the normal spray nozzle method, the discharged lubricant spreads on the roll due to the inertia force, and it is easy to supply it to places other than the lubrication supply area.When using a nozzle, supply a very small amount. It is preferable not to spread on the roll. As a method of supplying the lubricant while suppressing the spread of the lubricant on the roll, a lubricant supply unit is constituted by, for example, a felt, and the felt is impregnated with the lubricating oil. There is a method in which this is brought into contact with a roll, a method in which a lubrication supply unit is constituted by rollers divided in the axial direction, lubricating oil is applied to the rollers, and the rollers are brought into contact with a work roll. These supply methods may be appropriately selected in consideration of the space to be used, the use conditions such as the rolling speed and the temperature, and the like. At the edge, the range of the lubrication supply area or the non-lubrication supply area is set by changing the size of the lubrication supply unit 5 to be used. For example, when using spray chirping, the supply area is set by changing the nozzle diameter or the distance between the roll and the nozzle. When a roller or felt is used, the supply area is set by changing the axial length of the roller or felt as shown in FIG.

[0013] The lubricant supply area, always change in the lubricating rolling
Must . This is to prevent local roll abrasion and seizure of the lubrication non-supply portion. The change of the lubrication supply area is as shown in FIG. A method of changing the lubrication supply area by reciprocating the lubrication supply unit 5 of the lubrication supply device 6 in the axial direction of the work roll, or supplying lubrication to both the non-lubrication supply area and the lubrication supply area as shown in FIG. There is a method of installing a lubrication supply device in which units are arranged, and changing the lubrication supply region and the lubrication non-supply region by switching (ON / OFF) the supply of the lubricant to the lubrication supply unit. When the supply area is changed, the lubricating supply unit may be reciprocated as appropriate as shown in FIG. 3 as long as the lubricating supply unit is reciprocated. Or the reduction rate. That is, the roll speed is low. When the rolling reduction is small, the amount of seizure and abrasion is small and uneven wear and uneven seizure hardly occur. Therefore, there is no problem even if the reciprocating speed is low.
However, when the roll speed is high and the rolling reduction is large, seizure and abrasion tend to occur, so that the speed of the reciprocating motion may be increased to prevent uneven wear and uneven seizure.
In addition, as shown in FIG.
Also in the method of dividing by F, ON / OFF switching timing is determined according to the rolling conditions as described above. Since the optimum time varies depending on the roll material used and the rolling conditions, it is desirable that the time be determined empirically in the applied process.

Since the lubricant supplied to the lubrication supply area is almost burned off by contact with the hot steel material, the lubrication supply area can be clearly maintained. Therefore, the supply area is expanded due to the residual and diffusion of the lubricant, and the distinction from the non-lubrication non-supply area is not maintained.
It is preferable to supply an amount by which all of the lubricant can be burned out by the next supply timing.

In the present invention, any lubricant can be used regardless of the type of lubricant used. However, the supply mechanism must be appropriately changed depending on the difference in the viscosity of the lubricant. For example, when using a mineral oil-based lubricant having a relatively low viscosity, a method of supplying to a roll using felt or the like is used, but it is difficult to supply using a grease-based lubricant using felt or the like. Therefore, a mechanism that applies grease directly to the roll by an extruder or the like is more preferable. In any case, the present invention essentially separates a roll into a lubrication supply section and a non-supply section and lubricates and rolls the roll. The choice may be made according to the needs of the process for applying the invention.

The present invention exhibits a particularly effective effect in a batch process such as a normal hot rolling process.

[0017]

EXAMPLES ( Reference Example ) Hot strip rolling was performed using a 2Hi hot rolling mill.
The roll body width of the rolling mill was 200 mm. Roll diameter is 250
mm. The dimensions of the rolled material are thickness 10mm, width 10
0 mm and length 350 mm. The heating temperature of the material is 11
The temperature was set to 00 ° C., and the generation of a large amount of scale in the material by heating in a nitrogen atmosphere was suppressed. Fig. 1
As shown in (1), lubrication supply areas and non-lubrication supply areas were alternately provided with a width of 40 mm in the roll axis direction. Further, the experiment was performed by changing the width of the lubrication supply region from 10 mm to 70 mm. The width of the lubrication non-supply region at that time was changed from 70 mm to 10 mm corresponding to the width of the lubrication supply region.
The lubricant was applied to a roll in advance with the above width, and then the material was rolled. As the lubricant, a lubricant obtained by mixing graphite with grease was used. The amount of lubricant supplied is about 20
The thickness was adjusted to about 0 μm. The width of the lubrication supply area and the width of the non-lubrication supply area were changed to investigate the occurrence of rolling slip.
As a result, as shown in FIG. 5, there is a rolling slip generation limit near the ratio of the width of the lubrication supply area to the width of the non-lubrication supply area of about 1, and the rolling slip occurs within the range defined by the equation (1). Turned out not to be.

(Example 1 ) Hot coil rolling was carried out using a 4Hi rolling coil mill. The roll body width of the rolling mill is 100 mm, and the roll diameter is 70 mm. The dimensions of the coil material are 1 mm in thickness, 70 mm in width, and 700 m in length. The heating temperature of the material is 11
The temperature was set to 00 ° C., and the generation of a large amount of scale in the material by heating in a nitrogen atmosphere was suppressed. Rolling speed is 50m / m
in. The rolling was performed at a rolling reduction of 20% -constant. A tension of 1 kg / mm ^{2 was} applied on both the entrance and exit sides. As shown in FIG. 1, the lubricant was supplied in such a manner that lubrication supply areas and non-lubrication supply areas were alternately provided at 15 mm in the roll axis direction. Also,
The experiment was conducted for the width of the lubrication supply area of 15 mm and 30 mm. At this time, the width of the lubrication non-supply region was changed to 30 mm and 15 mm corresponding to the width of the lubrication supply region.
Lubricant was supplied by soaking the felt in the lubricant and bringing it into and out of the roll,
The width of the felt was adjusted to the width of the set lubrication supply area.
Lubrication was supplied by bringing the felt into contact with the roll for one rotation of the roll every 20 m of rolling. Lubricants were supplied and the puerto was then separated from the rolls and no lubrication was provided in the lubrication supply area. The contact load of the felt was adjusted so that the amount of lubricant supplied per time was such that the oil film thickness was 30 μm. The next lubrication is performed by changing the width of the felt, replacing the lubrication supply area with the lubrication non-supply area and replacing the lubrication non-supply area with the lubrication supply area, and lubricating each part of the roll at least once. The roll was rolled so as to be in the region to prevent uneven wear of the roll. A commercially available mineral oil-based lubricant was used as the lubricant. The amount of roll wear in relation to the ratio of the width of the lubrication supply area to the width of the non-lubrication supply area was investigated. As a result, the average roll wear depth changes according to the ratio of the width of the lubrication supply area to the width of the non-lubrication supply area, and the average roll wear depth decreases as the width of the lubrication supply area increases. Further, the roll wear is reduced as compared with the conventional roll wear when mixed with water. The variation in the roll wear depth also remained within 5% of the average roll wear depth, and it was clarified that the uneven roll wear due to the division into the lubrication supply region and the non-lubrication supply region was small (FIG. 6).

[0019]

According to the present invention, it is possible to directly apply a lubricant to a conventionally used lubricant without mixing and diluting it with water to prevent rolling slip. Roll wear and seizure can be reduced as compared with the conventional case.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a setting state of a lubrication supply area and a lubrication non-supply area in the present invention.

FIG. 2 is a diagram illustrating an example of an apparatus for supplying a lubricant to a lubrication supply area according to the present invention.

FIG. 3 is a diagram illustrating an example of a method of supplying a lubricant by changing a lubrication supply area and a non-lubrication supply area in the present invention.

FIG. 4 is a view showing another example of a method of supplying a lubricant by changing a lubrication supply area and a non-lubrication supply area in the present invention.

FIG. 5 is a diagram showing a relationship between a ratio between a lubrication supply region and a non-lubrication supply region, a friction coefficient, and a state of occurrence of rolling slip.

FIG. 6 is a diagram showing a relationship between a ratio of a lubrication supply region and a lubrication non-supply region in hot rolling and a wear amount of a rolling roll.

[Explanation of symbols]

 Reference Signs List 1 roll 2 roll center 3 lubrication supply area 4 lubrication non-supply area 5 lubrication supply unit 6 lubrication supply device 7 lubrication supply ON 8 lubrication supply OFF

Continuation of the front page (72) Inventor Fuyasu Yamamoto 20-1 Shintomi, Futtsu City Nippon Steel Corporation Technology Development Division (56) References JP-A-3-52704 (JP, A) JP-A-1-224105 (JP, A) JP-A-3-77701 (JP, A) JP-A-6-344011 (JP, A) JP-A-60-148606 (JP, A) JP-A-9-239402 (JP, A) JP-A-63-309590 (JP, A) JP-A-63-230796 (JP, A) JP-A-63-254195 (JP, A) JP-A-56-161897 (JP, A) JP, Y1) (58) Field surveyed (Int. Cl. ⁷ , DB name) B21B 27/10 B21B 1/22

Claims (3)

(57) [Claims] 1. A method for hot rolling a metal material using a work roll, comprising:
A lubricant supply area for supplying the lubricant and a non-lubrication supply area for not supplying the lubricant are alternately provided in the roll axis direction to supply the lubricant, and the positions of the lubricant supply area and the non-lubrication supply area are changed.
A hot lubricating rolling method characterized by rolling while further performing rolling. 2. The hot lubricating rolling method according to claim 1, wherein the lubrication supply region and the lubrication non-supply region are alternately provided in the roll axis direction, and follow Formula (1). ΣW ₀ ≦ ΣW ₁ ... (1) W ₀ : Length of the lubrication supply area in the roll axis direction W ₁ : Length of the non-lubrication supply section in the roll axis direction ΣW ₀ : Length of the lubrication supply area Total length in roll axis direction ΣW ₁ : Total length in roll axis direction of non-lubrication supply area 3. The lubrication supply area and the non-lubrication supply area are provided alternately in the roll axis direction and symmetrically with respect to a roll center. hot lubrication rolling method.