KR100368209B1 - Hot rolling apparatus and hot rolling method for preventing sticking defects of stainless steel - Google Patents

Abstract

PURPOSE: A hot rolling apparatus and a hot rolling method for preventing sticking defects of stainless steel are provided to secure superior surface quality of strip by spraying steam onto the surface of stainless strip, thereby preventing sticking phenomena of the stainless strip effectively. CONSTITUTION: In an apparatus for preventing sticking phenomena of the surface of the stainless strip (S) in rear of roughing mill(110) and in front of finishing mill(120) of hot rolling process for producing a stainless strip (S), the hot rolling apparatus for preventing sticking defects of stainless steel is characterized in that a plurality of steam spray nozzles(10) are installed in front of work rolls(130) so that steam is sprayed onto front and rear sides of the stainless strip (S) before the stainless strip (S) is rolled. In a method for preventing sticking phenomena of the surface of the stainless strip in rear of roughing mill and in front of finishing mill of hot rolling process for producing a stainless strip, the hot rolling method for preventing sticking defects of stainless steel comprises the steps of spraying steam onto front and rear sides of the stainless strip before the stainless strip is rolled by work rolls; rapidly producing scale layer of rough structure on the surface of the stainless strip using the steam; and performing lubrication rolling using the rough scale layer by the work rolls.

Description

Hot rolling apparatus and method for preventing sticking defects of stainless steel.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for preventing a sticking phenomenon mainly occurring between a rear end of a roughing mill and a front end of a finishing mill during a hot rolling process of a stainless steel, And more particularly, to a hot rolling apparatus and method for preventing sticking defects in an improved stainless steel so as to ensure an excellent surface quality by effectively preventing the sticking phenomenon by spraying steam on the surface of the stainless steel.

Generally, in the case of stainless steel, especially ferritic stainless steel, a part of the extreme surface layer of the rolled material is transferred to the surface of the roll at the rear stage of the rough rolling and the preliminary rolling stage to grow and grow, thereby causing sticking phenomenon Lt; / RTI > In order to overcome such a problem, as shown in FIG. 1, in the hot rolling step of producing the stainless steel material S, the roll 130 and the hot rolled steel sheet 130 are formed at the rear end of the rough rolling 110, The oil and the solid lubricant were sprayed onto the surface of the work roll 130 immediately before the hot rolling through the nozzle 140 for lubrication rolling between the rolled materials. This is to suppress the high-temperature fusion of the rolled material particles due to the oil film formed on the surface of the work roll 130 (see Iron and Steel, 9 (1991), P1458, Report on the Rolling Roller of the Japan Iron and Steel Association (1995, 2, P185). In detail, when the ferritic stainless steel material S drawn out from the heating furnace is rough-rolled after the rough rolling, the work roll 130 or the backup roll When oil and a solid lubricant are injected at an oil pressure of 10 kgf / cm 2 using an oil injection nozzle 140 on the side of the work roll 130 and the stainless steel material S, an oil film is formed between the work roll 130 and the stainless steel material S However, since this technique can prevent the sticking phenomenon, it is possible to prevent the sticking of the rolled material particles from the surface of the hot rolling mill by using oil and solid lubricant. When the atmosphere is polluted and the cooling water is contaminated And has a problem of neundeu, it will cause a frequent accidents tongpan property deterioration of the spirit rolling step by lubrication adversely affects the productivity.

In order to suppress the above-described problems, the material of the roll 130 having a small friction coefficient is selected and applied (Plasticity and Machining, 28 (1987), P284, Steel Research No. 335 (1989) , P35). However, these conventional technologies use oil and solid lubricant to pollute the working atmosphere of the hot rolling mill, pollute the cooling water, etc., and only a limited material can be used in selecting the material of the work roll 130, Has a problem that there is a limit in reducing the sticking occurrence rate.

In order to solve the above problems, it is an object of the present invention to provide a hot rolling mill which is capable of preventing the sticking phenomenon mainly occurring in the rear stage of the rough rolling and the shear rolling stage during the hot rolling operation of the stainless steel, And an object of the present invention is to provide a hot rolling apparatus and method for preventing sticking defects of an improved stainless steel so as to obtain a sticking prevention effect.

1 is a diagram showing a conventional hot rolling apparatus,

FIG. 2 is a schematic view showing a hot rolling apparatus for preventing sticking defects of stainless steel according to the present invention. FIG.

3 is a flowchart sequentially illustrating a hot rolling method for preventing sticking defects of a stainless steel according to the present invention.

Description of the Related Art

10 .... steam spray nozzle 110 .... rough rolling line

120 ... finish rolling line 130 .... work roll

140 ... Oil spray nozzle S ..... Stainless steel material

In order to accomplish the above object, the present invention provides an apparatus for preventing the sticking phenomenon on the surface of a stainless steel material at a rear end of rough rolling and a front end of preliminary rolling in a hot rolling step of producing a stainless steel material, Wherein steam is sprayed onto the front and rear surfaces of the stainless steel material before the stainless steel material is rolled by positioning the steam spray nozzles.

The present invention also provides a method for preventing the sticking phenomenon on the surface of the stainless steel material at the rear end of the rough rolling and the shear rolling front end of the hot rolling step of producing the stainless steel material, Spraying on the front and rear surfaces of the steel material; Feeding the scale layer of the rough texture to the surface of the stainless steel material by the steam; And performing a lubrication rolling process using a coarse scale layer by the work roll. The hot rolling method for preventing sticking defects of a stainless steel is provided.

Hereinafter, the present invention will be described in more detail with reference to the drawings.

As shown in FIG. 2, the hot rolling apparatus 1 for preventing sticking defects of the stainless steel according to the present invention comprises a hot rolling step of hot rolling the stainless steels S, A plurality of steam injection nozzles 10 are disposed at the front end of the work roll 130 at the front end of the stainless steel material S so as to spray steam onto the front and rear surfaces of the stainless steel material S before the stainless steel material S is rolled. The steam injection nozzle 10 is disposed so as to face the front and rear surfaces of the stainless steel material S and injects steam having a spraying pressure of approximately 15 Kgf / cm 2 to 25 Kgf / cm 2 onto the front and rear surfaces of the stainless steel material S.

The hot rolling method using the hot-rolled apparatus of the present invention will be described.

The stainless steel material S is drawn out from a heating furnace (not shown) and subjected to rough rolling. When the stainless steel material S flows into the finishing rolling line, as shown in FIG. 3, A step 200 of spraying steam on the front and rear surfaces of the stainless steel S at a pressure of 15 to 25 Kgf / cm 2 is performed. A step (S210) of steeping a scale layer of a rough texture on the surface of the stainless steel material S is performed by the steam. This is because in the case of the staking phenomenon of the stainless steel material S, Temperature strength and high-temperature oxidation amount of the steel material S, that is, it increases as the temperature decreases, and the high-temperature oxidation amount increases as the temperature increases. This sticking phenomenon is a phenomenon occurring in the contact chamber between the work roll 130 and the steel material S, and as the scale layer on the surface of the steel material becomes thicker, the nucleation destination of sticking generation is decreased by the lubrication rolling by the scale layer Therefore, if a thick scale layer is formed on the surface of the steel (S) before rolling, it can be prevented. Therefore, steam is sprayed on the surface of the steel material S before being rolled by the work roll 130, so that the scale layer of the coarse texture is steeped to perform lubrication rolling by scale during rolling, The effect of the method can be shown.

Next, a lubricating rolling operation 240 is performed using the rough scale layer by the work roll 130.

Table 1 below shows the occurrence of sticking defects when the sticking simulation test is performed after varying the thickness of the scale layer formed on the surface of the STS430 steel (S). From this result, the thickness of the scale layer When the thickness is 3.0 μm or less, sticking defects are likely to occur. This sticking phenomenon is a phenomenon occurring in the contact chamber between the work roll 130 and the steel material S, and as the scale layer on the surface of the rolled material becomes thicker, the nucleation destination of sticking generation during rolling due to lubrication rolling due to scale Therefore, in order to prevent the sticking phenomenon from the following results, it is necessary that the surface of the rolled material is at least 3.5 The sticking defects can be suppressed only if the thickness of the scale layer of 탆 or more is secured.

Table 1 (trend of occurrence of sticking defects according to the thickness of the scale layer formed on the surface of STS430 steel (S)).

0: a large amount of sticking occurred,?: A small amount of sticking occurred, and X: no sticking occurred.

Hereinafter, the effect of the present invention will be described in more detail by measuring the thickness of the steel material S (STS430) and the scale layer formed on the surface in the case of conducting the scale generation experiment using the present invention and the conventional technique. Table 2 below shows the results of the scale generation experiment by the conventional method and the method of the present invention and shows the thickness of the scale layer formed on the surface of the steel material S as a result. In the case of cooling to 1030 ° C (FM # 3 stand inlet) for about 80 seconds during R2 3 pass work (1140 ° C), which is the last high pressure water descaling process of the hot rolling process (normal rolling condition ), A case where a scale layer is formed according to the present invention by using a steam injection nozzle 10 of 25 kgf / cm2 at the FM inlet side and the F1 and F2 stand inlet side, and the case where a scale layer of 50 kgf / cm2 is used instead of the steam injection nozzle 10 After the high pressure water spray was installed, the thickness of the scale layer was measured by spraying high pressure water. As a result, in the case of the conventional rolling method, it was found that the scale layer had a thickness of 2.75 μm, whereas the working method of the present invention showed 5.84 μm. This result implies that the scale generation in the steam atmosphere is steeper and rougher than the scale generation in the atmosphere. On the other hand, as a result of performing high-pressure water injection as an intention to further increase the scale amount, the scale formation on the surface of the steel material S is not influenced by moisture and thus shows a low scale formation amount as compared with the steam atmosphere.

Therefore, as shown in Table 1, the rolling method according to the present invention satisfies the basic condition that the thickness of the scale layer should be at least 3.5 μm or more on the surface of the rolled material in order to prevent the sticking phenomenon.

Table 2 (the result of measuring the thickness of the scale layer on the surface of the steel material (STS430) in the case of conducting the scale generation test by the hot rolling method according to the conventional technique and the present invention)

Table 3 below shows the result of measuring the thickness of the scale layer on the surface of the steel material S (STS 430) according to the steam injection pressure in the case of conducting the scale generation test by the hot rolling method according to the present invention, and it is 15 Kgf / When the stamper injection pressure is low, the scale generation amount is small. If the steam injection pressure is 25 Kgf / cm 2 or more, the scale amount due to the high pressure is larger than the scale generation amount due to the submergence period, do.

Table 3 (Results of measurement of scale layer thickness on the surface of rolled material (STS 430) according to steam injection pressure when scale formation test was conducted by the hot rolling method according to the present invention)

As described above, according to the present invention, steam is sprayed onto the surface of the rolled material at the side of the work roll 130 in order to prevent the sticking phenomenon occurring during hot rolling in the hot rolling process equipment of the stainless steel material S, It is possible to obtain a stainless steel hot-rolled steel material S having excellent surface quality without defects. Therefore, according to the present invention, it is possible to prevent the sticking phenomenon mainly occurring at the rear end of the rough rolling and the shear rolling front during the hot rolling process of the stainless steel material (S), and to prevent sticking phenomenon, An improved effect can be obtained so as to obtain an effect.

Claims (3)

An apparatus for preventing sticking of a surface of a stainless steel material (S) at a rear end of a rough rolling (110) and a front end of a warp rolling (120) in a hot rolling step of producing a stainless steel material (S) Wherein a plurality of steam injection nozzles (10) are disposed at the front end so as to spray steam onto the front and rear surfaces of the stainless steel material (S) before the stainless steel material (S) is rolled. . A method for preventing sticking of a surface of a stainless steel material (S) at a rear end of a rough rolling (110) and at a front end of a warp rolling (120) in a hot rolling step of producing a stainless steel material (S) (200) spraying steam on the front and rear surfaces of the stainless steel (S) before the stainless steel (S) is rolled; A step (220) of stealing the scale layer of the rough texture on the surface of the stainless steel material (S) by the steam; And performing (240) lubrication rolling using a coarse scale layer by the work roll (130). ≪ Desc / Clms Page number 20 > 3. The method of claim 2, wherein the steam is sprayed onto the stainless steel (S) at a pressure of 15 to 25 kgf / cm < 2 > in the step (200).