Method for directly rolling fixed-length steel billet

Abstract

The invention relates to a method for directly rolling a fixed-length steel billet, which comprises the following steps of: shearing the steel billet to obtain the fixed-length steel billet with a preset length; whether the bending degree of the fixed-length steel billet with the preset length does not meet the standard bending degree or not is judged; if yes, the fixed-length steel billet is straightened under the condition of the preset opening degree of a straightening roller, and a straightened steel billet is obtained; and the straightened steel billet is rolled, and the fixed-length steel is obtained. The steel billet shearing frequency of the continuous casting hydraulic shear and the shearing number of online casting blanks are reduced, so that the shearing energy consumption of the hydraulic shear is reduced, metal waste in the steel billet rolling process is reduced, and the yield of steel is increased.

Description

Technical Field

[0001] The present application relates to the field of rolling technology, and in particular to a method for directly rolling a 20-meter-sized steel billet. Background Art

[0002] At present, after molten steel is smelted in the converter of a steel plant, it is lifted into cans and transported to the continuous casting machine to cast steel billets. The cross-section of the billet head passes through the shearing blades of the hydraulic shears and is transported to 12m in front of the hydraulic shears of the continuous casting machine, where the billet is sheared.

[0003] However, in the production of 12m long fixed-length billet rolling, the continuous casting machine hydraulic shears have many actions to shear the billet, the shear blades wear more, the energy consumption is higher, the total number of cuts is large, and the yield rate is low. Summary of the invention

[0004] The present application provides a method for directly rolling a 20-meter-long steel billet to solve the following technical problem: how to improve the yield rate of the steel billet.

[0005] In a first aspect, the present application provides a method for direct rolling of a cut-to-length steel billet, the method comprising:

[0006] Shearing the steel billet to obtain a steel billet of a preset length;

[0007] Determining whether the curvature of the fixed-length steel billet with a preset length does not meet the standard curvature;

[0008] If yes, the fixed-length steel billet is straightened under the condition of the preset opening of the straightening roller to obtain a straightened steel billet;

[0009] The straightened steel billet is rolled to obtain a steel product of a specified length.

[0010] Optionally, the standard curvature is ≤5×10 -4 .

[0011] Optionally, the preset opening degree is 155 mm to 160 mm.

[0012] Optionally, the number of straightening roller groups used for straightening is not less than 5 groups.

[0013] Optionally, the straightening roller speed is 1.5 m / s to 2.5 m / s.

[0014] Optionally, the starting temperature of the shearing, the starting temperature of the straightening and the starting temperature of the rolling are respectively ≥950°C.

[0015] Optionally, at the beginning of rolling, the difference between the head temperature of the cut-length steel billet and the tail temperature of the cut-length steel billet is ≤30°C.

[0016] Optionally, the preset billet length includes 20m.

[0017] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0018] The method for directly rolling a cut-length steel billet provided in an embodiment of the present application comprises: shearing the steel billet to obtain a cut-length steel billet with a preset length; judging whether the curvature of the cut-length steel billet with the preset length does not meet the standard curvature; if so, straightening the cut-length steel billet under the condition of a preset opening of a straightening roller to obtain a straightened steel billet; and rolling the straightened steel billet to obtain a cut-length steel product. The steel billet is sheared to obtain a fixed-length steel billet with a preset length, so as to reduce the number of times the continuous casting hydraulic shear shears the steel billet, reduce the waste of metal in cutting the head and tail during the rolling process, and thus increase the yield rate of the steel; and the fixed-length steel billet with the preset length has a high temperature and is too soft, and will bend after a slight collision or friction, so it is judged whether the fixed-length steel billet with the preset length reaches the standard bending degree; if not, the fixed-length steel billet with the preset length is straightened under the condition of the preset opening of the straightening roller before rolling, so that the 20-meter fixed-length steel billet can move forward quickly in the middle position of the horizontal roller without swinging left and right, so that the entire fixed-length steel billet is straightened continuously to ensure that the billet size is qualified, thereby increasing the yield rate of the steel. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0020] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0021] Figure 1 A schematic flow chart of a method for directly rolling a 20-meter-long steel billet provided in an embodiment of the present application;

[0022] Figure 2 A schematic diagram of the structure of a straightening device in a method for directly rolling a 20-meter-long steel billet provided in an embodiment of the present application. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0024] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be understood as a rigid limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, the range description from 1 to 6 should be considered to have specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0025] In this application, unless otherwise specified, directional words such as "upper" and "lower" used refer specifically to the directions of the drawings in the accompanying drawings. In addition, in the description of the specification of this application, the terms "include", "comprise", etc. mean "including but not limited to".

[0026] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0027] In order to reduce the shearing times of continuous casting hydraulic shears and the shearing number of online casting billets, thereby reducing the shearing energy consumption of hydraulic shears, and reducing metal waste during billet rolling, increasing the yield rate of steel, and changing the short billet direct rolling process, the present application provides a method for direct rolling of fixed-length billets. Figure 1 A schematic diagram of a process for direct rolling of a steel billet of a fixed length provided in an embodiment of the present application; see Figure 1 , the method comprising:

[0028] S1, shearing the steel billet to obtain a steel billet of a preset length;

[0029] In some embodiments, the preset length includes 20m.

[0030] S2, determining whether the curvature of the fixed-length steel billet with a preset length does not meet the standard curvature;

[0031] If yes, the fixed-length steel billet is straightened under the condition of the preset opening of the straightening roller to obtain a straightened steel billet;

[0032] In some embodiments, the standard curvature is ≤5×10 -4 .

[0033] In some embodiments, the preset opening degree is 155 mm to 160 mm.

[0034] S3, rolling the straightened steel billet to obtain a steel product of a specified length.

[0035] In the embodiment of the present application, a method for directly rolling a fixed-length steel billet is preferably a method for directly rolling a 20-meter fixed-length steel billet. The steel billet is sheared to obtain a fixed-length steel billet with a preset length, so as to reduce the number of times the continuous casting hydraulic shear shears the steel billet, reduce metal waste during the rolling process, and thus increase the yield rate of the steel; and the fixed-length steel billet with a preset length has a high temperature, is too soft, and will bend after a slight collision or friction, then it is judged whether the fixed-length steel billet with a preset length reaches the standard bending degree; if not, the fixed-length steel billet with a preset length is straightened before rolling under the condition of the preset opening of the straightening roller, so that the 20-meter fixed-length steel billet can move forward quickly in the middle position of the horizontal roller without swinging left and right, so that the entire fixed-length steel billet is continuously straightened to ensure that the billet size is qualified, thereby increasing the yield rate of the steel.

[0036] In some embodiments, the number of straightening roller groups used for straightening is not less than 5.

[0037] In some embodiments, the straightening roller speed is 1.5 m / s to 2.5 m / s.

[0038] In the embodiment of the present application, a 20m long high-temperature fixed-length steel billet will collide or rub against the roller and the side baffle connected to it during rapid transportation. Since the 20m long high-temperature fixed-length steel billet is too soft, it will bend after a slight collision or friction. When the high-temperature transported steel billet arrives in front of the first rough rolling mill in the steel rolling process, the high-temperature steel billet is bent and may not be perpendicular to the rolling mill rollers, but has a certain angle. The head of the steel billet cannot be fed into the mill opening and cannot be rolled. This may cause the steel billet to be scrapped and needs to be cleaned off the roller in time, causing a temporary interruption in production. The roller side rejection device is required to move the steel billet out from the upper side of the roller. This production mode wastes steel billets and production time, has low production efficiency, reduces the yield rate, and increases the cost of secondary handling off the line. In view of this, after shearing, it is determined whether the curvature of the fixed-length steel billet with a preset length does not meet the standard curvature (≤5×10 -4); Install a straightening machine with no less than 5 straightening rollers in front of the first rough rolling mill in the rolling area to straighten the billet, eliminate the risk of billet bending, and straighten the high-temperature billet before entering the first rolling mill. Specifically, the cross-section is 150mmX150mm, and the length is 20m to achieve a standard bending degree of ≤5×10 -4 , which solves the problem that the high-temperature billet cannot be bitten into the rolling mill due to bending, thereby reducing the possibility of billet rejection, eliminating the short billet rejection process, and omitting the original rejection device. Figure 2 This is a schematic diagram of the structure of a straightening device in a method for directly rolling a 20-meter-long steel billet provided in an embodiment of the present application; see Figure 2 , a straightening machine with 10 rollers of high-temperature steel billets is installed in front of the first rough rolling mill in the rolling area to straighten the steel billets and eliminate the risk of steel billet bending. The ten straightening rollers are the same. The opening of the straightening is limited to 155mm-160mm, so that the whole steel billet can move forward quickly in the middle position of the horizontal roller without swinging left and right, so that the whole steel billet 20m steel billet can be straightened continuously. Exemplarily, the preset opening of the straightening roller can be 155mm, 156mm, 157mm, 158mm, 159mm, 160mm, etc. At the same time, the speed of the straightening is 1.5m / s-2.5m / s, so that the straightening process can proceed smoothly, and the temperature of the 20m steel billet reaching the starting point of the first rolling mill is not less than 950℃. Exemplarily, the straightening speed can be 1.5m / s, 1.7m / s, 1.9m / s, 2.1m / s, 2.3m / s, 2.5m / s, etc.

[0039] In addition, if the curvature of the 20m billet is ≤5×10 -4 , no straightening is required, and the billet can quickly pass through the opening of the straightening machine, and the head can directly enter the first rolling mill for rolling, which is flexible and maneuverable. The 12m long fixed-length billet is optimized to a fixed-length rolling within 20m, and eventually tends to a continuous rolling process with less or no head.

[0040] In some embodiments, the starting temperature of the shearing, the starting temperature of the straightening, and the starting temperature of the rolling are respectively ≥ 950°C.

[0041] In the embodiment of the present application, the starting temperature of shearing, the starting temperature of straightening and the starting temperature of rolling are ≥950℃ respectively. Specifically, the upper insulation cover and the lower insulation cover are installed on the upper and lower parts of the shearing conveying roller in the casting area. The two are combined to form a sealed box, which seals the steel billet inside, is not easy to fan heat, has a good insulation effect on the steel billet, ensures that the fixed-length steel billet reaches the entrance of the first rolling mill, and realizes that the 20-meter fixed-length steel billet between the starting point of the hydraulic press shearing and the starting point of the rolling is in an insulation environment, so that the starting temperature of shearing, the starting temperature of straightening and the starting temperature of rolling can be ≥950℃ respectively, which can meet the needs of directly entering the rolling mill for steel rolling, and no secondary heating or heating is required, thereby reducing energy consumption, reducing oxidation and burning of steel billets caused by secondary heating of steel billets, reducing logistics and transportation costs, and reducing heating gas consumption, reducing SO2, NOx, dust and other pollution emissions, and eliminating the cooling water, compressed air and grease consumption of the heating furnace in the original production mode. For example, the starting temperature of the shearing, the starting temperature of the straightening and the starting temperature of the rolling can be 950°C, 960°C, 970°C, 980°C, 990°C, 1000°C, etc. In addition, a slag leakage hole is provided in the middle of the lower heat preservation cover, and the oxidized slag on the surface during the high-temperature ingot conveying process flows into the slag leakage hole, into the conduit and into the steel slag collecting tank.

[0042] In some embodiments, the difference between the head temperature of the cut-length steel billet and the tail temperature of the cut-length steel billet at the beginning of rolling is ≤30°C.

[0043] In the embodiment of the present application, when the casting speed of the continuous casting machine is constant, there is a difference in temperature between the head and the tail of the long billet. The longer the fixed-length billet, the greater the temperature difference between the head and the tail if no measures are taken. Direct rolling control is difficult and requires high standards. Therefore, the difference between the head temperature of the fixed-length billet and the tail temperature of the fixed-length billet at the beginning of rolling is limited to ≤30°C. Exemplarily, the above difference can be 30°C, 28°C, 26°C, 24°C, etc. Further, after the high-temperature billet is sheared by the hydraulic shear of the continuous casting machine, it is quickly transported to the entrance of the straightening machine of the rolling production line. The straight-line distance between the hydraulic shear and the first rolling mill is 165m, and the conveying roller speed is 5m / second. The head of the high-temperature fixed-length billet can quickly reach the entrance of the first rolling mill of the rolling production line in 29 seconds and 20m.

[0044] The present application provides a method for directly rolling a 20-meter-long steel billet, which has at least the following beneficial effects:

[0045] The original 12m billet length was extended to 20m for rolling. The weight of the 20m high-temperature fixed-length billet rolled steel increased. After the billet length became longer, the fixed length of the head and tail of each billet was about 100mm, which did not change year-on-year. The weight ratio of the 20m billet was reduced, and the total number of heads was reduced. The reduced head and tail metal was rolled into qualified finished steel, which increased the metal yield and benefit.

[0046] The process of rejecting waste billets at the front entrance of the rolling mill was cancelled, and 20m long fixed-length high-temperature steel billets were used for rolling. Compared with the shearing of each 12m short billet, the continuous casting machine hydraulic shears reduced the number of shearing times by 0.67 times, the shearing action of the hydraulic shears was reduced, the wear of the shear blades was reduced, the energy consumption of equipment operation was reduced, and the wear was reduced.

[0047] The present application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are intended only to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods for which specific conditions are not specified in the following examples are usually measured according to national standards. If there is no corresponding national standard, then the conditions recommended by the manufacturer are followed.

[0048] Example 1

[0049] A method for directly rolling a steel billet of a specified length, comprising:

[0050] S11, shearing the steel billet to obtain a steel billet of a preset length;

[0051] S21, determining whether the curvature of the fixed-length steel billet with a preset length does not meet the standard curvature;

[0052] If yes, the fixed-length steel billet is straightened under the condition of the preset opening of the straightening roller to obtain a straightened steel billet;

[0053] S31, rolling the straightened steel billet to obtain a steel product of a specified length.

[0054] The preset length is 20m, which is judged as not meeting the standard curvature, the preset opening is 155mm, the number of straightening rollers used for straightening is 5, and the straightening roller speed is 2m / s.

[0055] The starting temperature of shearing, the starting temperature of straightening, and the starting temperature of rolling are 1000°C, 960°C, and 950°C, respectively.

[0056] At the beginning of rolling, the temperature difference between the head of the cut-length billet and the tail of the cut-length billet is 30°C.

[0057] Example 2

[0058] A method for directly rolling a steel billet of a specified length, comprising:

[0059] S12, shearing the steel billet to obtain a steel billet of a preset length;

[0060] S22, determining whether the curvature of the fixed-length steel billet with a preset length does not meet the standard curvature;

[0061] If yes, the fixed-length steel billet is straightened under the condition of the preset opening of the straightening roller to obtain a straightened steel billet;

[0062] S32, rolling the straightened steel billet to obtain a steel product of a specified length.

[0063] The preset length is 20m, which is judged as not meeting the standard curvature, the preset opening is 150mm, the number of straightening rollers used for straightening is 5, and the straightening roller speed is 2.5m / s.

[0064] The starting temperature of shearing, the starting temperature of straightening, and the starting temperature of rolling are 1000°C, 960°C, and 950°C, respectively.

[0065] At the beginning of rolling, the temperature difference between the head of the cut-length billet and the tail of the cut-length billet is 30°C.

[0066] Example 3

[0067] A method for directly rolling a steel billet of a specified length, comprising:

[0068] S13, shearing the steel billet to obtain a steel billet of a preset length;

[0069] S23, determining whether the curvature of the fixed-length steel billet with a preset length does not meet the standard curvature;

[0070] If yes, the fixed-length steel billet is straightened under the condition of the preset opening of the straightening roller to obtain a straightened steel billet;

[0071] S33, rolling the straightened steel billet to obtain a steel product of a specified length.

[0072] The preset length is 20m, which is judged as not meeting the standard curvature, the preset opening is 160mm, the number of straightening rollers used for straightening is 5, and the straightening roller speed is 2.2m / s.

[0073] The starting temperature of shearing, the starting temperature of straightening, and the starting temperature of rolling are 1000°C, 960°C, and 950°C, respectively.

[0074] At the beginning of rolling, the temperature difference between the head of the cut-length billet and the tail of the cut-length billet is 30°C.

[0075] Please analyze the method of direct rolling of a fixed-length steel billet provided in Examples 1 to 3. The analysis results are shown in Table 1. Table 1 Analysis of the method of direct rolling of a fixed-length steel billet

[0076]

[0077]

[0078] It can be seen from Table 1 that the friction force is large during straightening, the straightening speed is lower than the fast conveying speed, and the straightening opening of 150mm~160mm can meet the requirements of billet straightening. After the billet passes through the straightening opening, the temperature difference between the head and the tail does not change significantly by 30℃, which meets the technical requirements of the rolling mill.

[0079] After the billet passes through the straightening process, the head of the billet enters the mill roll gap perpendicular to the mill roll gap. The billet rolling temperature range is 950-960℃, and the actual head temperature is 950-960℃; the middle temperature is 955-980℃; the tail temperature is 975-1000℃. The finishing rolling temperature is 920-950℃, and the temperature of the steel cooling bed is 870-920℃ to obtain the finished steel product of fixed length.

[0080] The mechanical properties of the rolled steel were tested, and the test results are shown in Table 2.

[0081] Table 2 Mechanical properties of steel after rolling

[0082] Serial number Tensile strength Rm Yield Strength Rel Example 1 632MPa 464MPa Example 2 639MPa 466MPa Example 3 643MPa 469MPa

[0083] In summary, the mechanical properties of the finished steel products after rolling the 20-meter steel billet meet the production requirements. The average tensile strength Rm of the HRB400E steel bar reaches 639MPa, and the average yield strength Rel reaches 466MPa.

[0084] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A method for direct rolling of a fixed-length steel billet, characterized in that: The method comprises: Shearing the steel billet to obtain a steel billet of a preset length; Determining whether the curvature of the fixed-length steel billet with a preset length does not meet the standard curvature; If yes, the fixed-length steel billet is straightened under the condition of the preset opening of the straightening roller to obtain a straightened steel billet; The straightened steel billet is rolled to obtain a steel product of a specified length.

2. The method according to claim 1, characterized in that The standard curvature is ≤5×10 -4 .

3. The method according to claim 1, characterized in that The preset opening degree is 155 mm to 160 mm.

4. The method according to claim 1, characterized in that: The number of straightening roller groups used for straightening is not less than 5 groups.

5. The method according to claim 1, characterized in that The straightening roller speed is 1.5m / s to 2.5m / s.

6. The method according to claim 1, characterized in that The starting temperature of the shearing, the starting temperature of the straightening, and the starting temperature of the rolling are respectively ≥950° C.

7. The method according to claim 1, characterized in that At the beginning of rolling, the difference between the head temperature of the cut-length steel billet and the tail temperature of the cut-length steel billet is ≤30°C.

8. The method according to claim 1, characterized in that The preset length includes 20m.

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