Method for improving stability of hot-rolled high-speed steel roller oxidation film in rough rolling process

Abstract

The invention provides a method for improving the stability of a hot-rolled high-speed steel roller oxide film in a rough rolling process, which comprises the following steps of: checking the comprehensive intersection of a roller before the roller is loaded on a machine; the surface peak temperature of the roller is controlled in different intervals in different using stages of the roller; a lubricating rolling technology is adopted in the rolling process, and the rolling oil-water ratio is controlled. The stability of a roller oxidation film can be improved, and then the pressing-in defect of product oxide scale is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of metal materials, and in particular to a method for improving the stability of a rough rolling process of an oxide film on a hot-rolled high-speed steel roller. Background Art

[0002] During hot rolling, the rolls are exposed to high temperatures and humidity for extended periods, inevitably leading to high-temperature oxidation. When the resulting oxidation product has the right composition and thickness, it largely prevents air and water vapor from directly contacting the rolls, effectively reducing the corrosion rate on the roll surface and alleviating damage to the roll surface from the hot slab. However, when the oxidation product has an inappropriate composition or is too thick, it will immediately flake off, forming oxide scale defects on the strip surface. Therefore, controlling the stability of the oxide film on the roll surface has always been a key priority for mills.

[0003] The Chinese patent document with publication number CN110280605A discloses a method for reducing the peeling rate of the oxide film on the roller. Its main feature is to control the temperature deviation of the rolling process, specifically including that the temperature fluctuation of the entire length of the rolled material is less than 10°C, and the target temperature difference between the same batch of rolled materials is less than 20°C, etc. The control requirements are high and the control is difficult. The Chinese patent document with publication number CN101003053A discloses a method for preventing the peeling of the oxide film on the surface of the nickel-chromium roller. Its feature is the control of the oxide film of the nickel-chromium roller in the stainless steel rolling process. The Chinese patent document with publication number CN105598172A discloses a method for preventing the peeling of the oxide film on the surface of the roller of the hot steel continuous rolling mill. Its main feature is to spray coolant into the roller gap to keep the roller surface moist, thereby preventing the oxide film from peeling. The control range is relatively vague. Chinese patent document CN108687134A discloses a method for reducing thermal stress peeling of the oxide film on the roller. Its main feature is to reduce the heat transfer when the strip is in contact with the roller, thereby achieving the purpose of lowering the roller temperature, reducing roller thermal stress cracks and improving product surface quality. Summary of the Invention

[0004] In response to the aforementioned technical problems, a method is provided for improving the stability of the oxide film on hot-rolled high-speed steel rolls during rough rolling. This invention primarily addresses the oxidation characteristics of the rolls, fundamentally controlling the growth rate of oxidation products and oxide films on the roll surfaces during rolling. Furthermore, by reducing the overall cross-over of the rolls and the rolling load, the risk of the roll surface being subjected to shear loads is reduced, thereby achieving the goal of improving the stability of the roll oxide film.

[0005] The technical means adopted in the present invention are as follows:

[0006] A method for improving the stability of a hot-rolled high-speed steel roll oxide film rough rolling process comprises the following steps:

[0007] Before the rolls are put on the machine, the comprehensive cross-calculation of the rolls is verified;

[0008] Controlling the peak temperature of the roll surface in different ranges at different stages of roll use;

[0009] During the rolling process, lubrication rolling technology is adopted to control the rolling oil-water ratio.

[0010] Furthermore, before the rolls are put into operation, the comprehensive cross-check of the rolls is performed, including:

[0011] Before the roller bearing seat is installed on the machine, the matching accuracy between the bearing seat and the rolling mill arch is checked. The installed roller bearing seat is in close contact with the load-bearing surface of the rolling mill arch, so that the comprehensive cross of the roller system is less than 0.02°.

[0012] Furthermore, the axial movement of the roller is less than 1 mm.

[0013] Furthermore, controlling the peak temperature of the roll surface in different ranges at different stages of the roll use includes:

[0014] Different temperature ranges are used in the initial rolling stage and the stable rolling stage;

[0015] When a new roll is put into operation or the machine has been stopped for more than 2 hours, the peak temperature of the roll surface is controlled at the first temperature in the first 5 minutes of rolling, so that a dense oxide film is quickly formed on the roll surface;

[0016] Afterwards, the roller surface temperature is lowered to a second temperature to reduce the growth rate of the roller oxide film.

[0017] Furthermore, the first temperature is 650°C to 680°C.

[0018] Furthermore, the second temperature is 550°C to 600°C.

[0019] Furthermore, the second temperature is 550°C.

[0020] Furthermore, the rolling oil-water ratio is controlled at 0.9% to 1.3%.

[0021] Furthermore, the rolling oil-water ratio is controlled at 1.1%.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] Based on a thorough analysis of the oxidation characteristics of high-speed steel rolls at different temperatures, this paper proposes a quantitative control method for maintaining the roll surface temperature within different temperature ranges during different rolling stages. This method allows for more accurate control of the composition and growth rate of the roll oxide film, providing greater guidance. Furthermore, by controlling the roll crossover and reducing the rolling load, the shear load on the roll surface is reduced, improving the stability of the roll oxide film and, in turn, reducing the risk of scale intrusion defects in the finished product.

[0024] Based on the above reasons, the present invention can be widely promoted in the field of stability control of oxide film on the surface of rollers. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0026] Figure 1 Flowchart of the method of the present invention. DETAILED DESCRIPTION

[0027] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0028] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0029] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0030] Unless otherwise specified, the relative arrangement of the parts and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be clear that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to actual proportional relationships. The technology, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be considered as a part of the specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of the exemplary embodiments can have different values. It should be noted that similar numbers and letters represent similar items in the following drawings, and therefore, once an item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0031] In the description of the present invention, it should be understood that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "horizontal, vertical, vertical, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention: the directional words "inside and outside" refer to the inside and outside relative to the outline of each component itself.

[0032] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used herein to describe the spatial positional relationship of a device or feature to other devices or features as shown in the figures. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figures. For example, if the device in the drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below their position devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0033] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0034] Example 1

[0035] The technical problem to be solved by the present invention is: by reasonably controlling the peak temperature of the high-speed steel roll surface and moderately reducing the rolling load, the thickness of the roll oxide film can be controlled, the stability of the high-speed steel roll oxide film can be improved, and the product iron oxide scale indentation defect can be reduced.

[0036] This invention primarily focuses on the oxidation characteristics of the rolls to fundamentally control the oxidation products and oxide film growth rate on the roll surfaces during the rolling process. By reducing the overall roll crossover and rolling load, the risk of the roll surface being subjected to shear loads is reduced, thereby achieving the goal of improving the stability of the roll oxide film.

[0037] The present invention provides a method for improving the stability of the oxide film rough rolling process of a hot-rolled high-speed steel roll, comprising the following steps:

[0038] First, the peak roll surface temperature (hereinafter referred to as roll surface temperature) is controlled within different ranges during different stages of roll operation. Specifically, when a new roll is put into operation or has been idle for more than two hours, the roll surface temperature is controlled between 650°C and 680°C during the first five minutes of rolling to quickly form a dense oxide film on the roll surface. The roll surface temperature is then lowered to between 550°C and 600°C, preferably to 550°C, to reduce the growth rate of the oxide film.

[0039] Secondly, the roller bearing seat of the upper machine is made to fit tightly with the load-bearing surface of the rolling mill arch. At this time, the comprehensive cross-angle of the roller system is less than 0.02°, which further reduces the axial movement of the roller to less than 1mm.

[0040] Finally, a lubrication rolling mode is adopted, and the rolling oil-water ratio is controlled at 0.9% to 1.3%, preferably 1.1%, to reduce the load of the rolling process and improve the stress conditions of the rolls.

[0041] Example 2

[0042] The present invention provides a method for improving the stability of the oxide film rough rolling process of a hot-rolled high-speed steel roller, comprising the following steps:

[0043] (1) Before the roller bearing seat is installed, the matching accuracy between the bearing seat and the rolling mill arch is verified to ensure that the comprehensive crossover of the roller system is less than 0.02°. Here, 0.02° refers to the average distance between the two roller axes projected on the water surface. The angle can be expressed as: the angle between the roller axes projected on the horizontal plane is less than or equal to 0.01°; (2) Use lubrication rolling technology, and control the rolling oil-water ratio to 0.9% to 1.3%, preferably 1.1%; (3) Use different temperature ranges in the initial rolling stage (first 5 minutes) and the stable rolling stage. In the first 5 minutes of rolling, the roller surface temperature is controlled at 650℃ to 680℃ to quickly form a dense oxide film on the roller surface. Then, the roller surface temperature is reduced to 550℃ to 600℃, preferably 550℃, to reduce the growth rate of the roller oxide film.

[0044] Prior to the implementation of this invention, roll cross-checking was generally not performed, and lubrication rolling was not employed. Roll surface temperature was typically controlled at a constant temperature, with typical roll surface temperatures around 500°C and 700°C. The table below compares the scale indentation defect rates of products produced using each process for one month.

[0045]

[0046] The present invention can be extended and applied to other hot rolling production lines.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for improving the stability of the rough rolling process of the oxide film of hot-rolled high-speed steel rollers, characterized in that: The steps include: Before the rolls are put on the machine, the comprehensive cross-calculation of the rolls is verified; Controlling the peak temperature of the roll surface in different ranges at different stages of roll use; During the rolling process, lubrication rolling technology is adopted to control the rolling oil-water ratio.

2. The method for improving the stability of the oxide film rough rolling process of hot-rolled high-speed steel rolls according to claim 1, characterized in that: Before the rolls are put on the mill, the comprehensive cross-check of the rolls includes: Before the roller bearing seat is installed on the machine, the matching accuracy between the bearing seat and the rolling mill arch is checked. The installed roller bearing seat is in close contact with the load-bearing surface of the rolling mill arch, so that the comprehensive cross of the roller system is less than 0.02°.

3. The method for improving the stability of the rough rolling process of the oxide film of the hot-rolled high-speed steel roller according to claim 2, characterized in that: The axial movement of the roller is less than 1mm.

4. The method for improving the stability of the rough rolling process of the oxide film of the hot-rolled high-speed steel roller according to claim 1, characterized in that: Controlling the peak temperature of the roll surface in different ranges at different stages of roll use includes: Different temperature ranges are used in the initial rolling stage and the stable rolling stage; When a new roll is put into operation or the machine has been stopped for more than 2 hours, the peak temperature of the roll surface is controlled at the first temperature in the first 5 minutes of rolling, so that a dense oxide film is quickly formed on the roll surface; Afterwards, the roller surface temperature is lowered to a second temperature to reduce the growth rate of the roller oxide film.

5. The method for improving the stability of the rough rolling process of the oxide film of the hot-rolled high-speed steel roller according to claim 4, characterized in that: The first temperature is 650°C to 680°C.

6. The method for improving the stability of the oxide film rough rolling process of hot-rolled high-speed steel rolls according to claim 5, characterized in that: The second temperature is 550°C to 600°C.

7. The method for improving the stability of the oxide film rough rolling process of hot-rolled high-speed steel rolls according to claim 6, characterized in that: The second temperature is 550°C.

8. The method for improving the stability of the oxide film rough rolling process of hot-rolled high-speed steel rolls according to claim 1, characterized in that: The rolling oil-water ratio is controlled at 0.9% to 1.3%.

9. The method for improving the stability of the oxide film rough rolling process of hot-rolled high-speed steel rolls according to claim 8, characterized in that: The rolling oil-water ratio is controlled at 1.1%.

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