A control method for improving the surface quality of hot-rolled wheel steel

Abstract

The present application relates to a kind of control methods for improving the surface quality of hot-rolled wheel steel, belong to the technical field of hot-rolled strip surface quality control.The technical scheme is: by early prediction intermediate rolled piece finish rolling inlet temperature, by dynamic adjustment roughing descaling pass and rolling pass, the mode of manual intervention roughing descaling pass and rolling pass is changed into automatic control mode.The present application has beneficial effects: the finish rolling inlet temperature of intermediate blank can be quickly, accurately, real-time and simply controlled, the qualified rate of intermediate blank finish rolling inlet temperature can be greatly improved to more than 92%, effectively reduces the probability of secondary oxide scale indentation defect of finished strip steel, and can make finished strip steel obtain thinner and more uniform tertiary oxide scale.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of control method for improving the surface quality of hot-rolled wheel steel, further improve the surface quality of hot-rolled wheel steel, belong to the technical field of hot-rolled strip surface quality control. BACKGROUND

[0002] Steel wheel assembly is combined by rim and spoke, and the spoke and the rim are obtained by a series of strict manufacturing processes such as spinning (rolling) forming, welding, pickling, paint spraying and the like. In addition to the physical properties, the hot-rolled steel plate for making wheels has high requirements on the surface quality, and the primary and secondary scale defects are not allowed to be pressed in, and the steel strip is required to have a thinner and more uniform tertiary scale. Generally, during the wheel processing, the hot plate raw material does not usually go through pickling, and if the steel strip surface has primary and secondary scale defects pressed in, stress concentration is easily generated during the spinning and stamping deformation of the wheel, causing scratches and cracks on the original plate during the manufacturing process, resulting in scrap. In addition, the thicker and unevenly distributed tertiary scale has poor conductivity, which is not conducive to the weld quality of the rim, and can cause high cracking rate after welding, affecting the yield. Generally, the hot plate raw material of the wheel steel is thicker, with a thickness of > 4.0 mm, and the rolling force of the rolling mill is lower, so the temperature requirement for the intermediate rolled piece is not high. Therefore, controlling the finish rolling inlet temperature of the intermediate blank in a lower temperature range will not affect the rolling stability, and can effectively control the secondary scale pressed-in defect and the thickness of the tertiary scale, effectively reducing or eliminating the surface pit defect. At present, the finish rolling inlet temperature of the intermediate rolled piece in the hot rolling line is mainly controlled manually by the operator, that is, the operator changes the roughing descaling pass, roughing rolling pass and intermediate rolled piece oscillation swing steel to realize the control. In the case of steel grade transition and frequent change of intermediate blank thickness, it is difficult to ensure that the finish rolling inlet temperature of the intermediate blank is within the allowable range by manual intervention, and the qualified rate of the finish rolling inlet temperature is not more than 60%. This will inevitably cause the instability of the surface quality of the hot-rolled strip. SUMMARY

[0003] The present application aims to provide a control method for improving the surface quality of hot-rolled wheel steel, which can quickly, accurately, real-time and simply control the finish rolling inlet temperature of the steel strip by using big data multivariate regression formula to predict the finish rolling inlet temperature of the intermediate blank in advance, and changing the manual intervention roughing descaling pass and rolling pass to automatic control mode, thereby improving the finished product quality.

[0004] The technical solution of the present application is:

[0005] A control method for improving the surface quality of hot-rolled wheel steel, by predicting the finish rolling inlet temperature of the intermediate rolled piece in advance, dynamically adjusting the rough rolling descaling pass and rolling pass, and changing the manual intervention rough rolling descaling pass and rolling pass to an automatic control mode; the process includes slab heating, post-furnace descaling, rough rolling, finish rolling, and cooling coiling processes, and the post-furnace descaling process is completed to predict the finish rolling inlet temperature calculation value FET C in advance C , which is determined by the following formula 1

[0006] FET C = K - 0.0804 * W - 6.53 * R2 F + 0.2775 * RET + 0.902 * H R - 9.10 * R2 D (1)

[0007] In formula (1), 850 ≤ K ≤ 851, FET C is the finish rolling inlet temperature calculation value of the intermediate slab, W is the target width of the finished product, R2 F is the rolling pass number of the R2 rough rolling mill, RET is the post-furnace descaling outlet slab temperature detection value, H R is the thickness set value of the intermediate slab, R2 D is the descaling pass number of the R2 rough rolling mill, W, H R are all in mm, FET C and RET are all in ℃, R2 F , R2 D are in passes.

[0008] The formula (1) reports that K = 850.7.

[0009] In the rough rolling process, before rough rolling, the initial default rough rolling mill R1 and R2 use 3 rolling passes, and R1 and R2 use 1 and 3 descaling passes at the inlet and outlet, when the finish rolling inlet temperature deviation △t (△t = FET C - FET t ) satisfies 10℃ ≤ △t < 20℃, the two rough rolling mills increase 2 descaling passes based on the default rolling pass and descaling pass; when 20℃ ≤ △t < 30℃, the two rough rolling mills increase 2 descaling passes based on the default rolling pass and descaling pass; when △t ≥ 30℃, the rough rolling mill R1 uses the default rolling pass and descaling pass, and the rough rolling mill R2 uses 5 rolling passes and all of them are descaling; when △t < 10℃, the two rough rolling mills use the default rolling pass and descaling pass.

[0010] In the finish rolling process, the finish rolling inlet target temperature FET t is determined according to the thickness h of the steel plate finished product: when h < 6.0mm, FETt is 1005℃; when 6≤h<10.0mm, FET t is 985℃; when h≥10.0mm, FET t is 970℃.

[0011] In the heating process, the slab heating temperature is determined according to the thickness specification h of the finished steel plate: when h<6.0mm, the slab heating temperature is 1180-1230℃; when 6.0mm≤h<10.0mm, the slab heating temperature is 1130-1180℃; when h≥10.0mm, the heating temperature is 1090-1140℃.

[0012] The present application has the advantages that the finishing entry temperature of the intermediate piece can be quickly, accurately, real-timely and simply controlled, the finishing entry temperature of the intermediate piece is controlled by dynamically adjusting the roughing descaling pass and the rolling pass, the qualified rate of the finishing entry temperature can be greatly increased to more than 92%, the probability of the secondary iron oxide skin pressing defect of the finished steel strip is effectively reduced without increasing additional equipment, and the finished steel strip can obtain the third iron oxide skin with thinner and more uniform thickness. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 is a flowchart of the embodiment of the present application;

[0014] Figure 2 is a hot rolling line process layout diagram of the embodiment of the present application. DETAILED DESCRIPTION

[0015] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below in combination with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application.

[0016] A control method for improving the surface quality of hot-rolled wheel steel, by predicting the finishing entry temperature of the intermediate piece in advance, dynamically adjusting the roughing descaling pass and the rolling pass, and changing the manual intervention roughing descaling pass and rolling pass to an automatic control mode; the process includes the heating of the slab, the post-furnace descaling, the roughing, the finishing and the cooling coiling process, the finishing entry temperature calculation value FET C is determined in advance after the post-furnace descaling process is completed. C is determined by the following formula 1.

[0017] FET C =K-0.0804*W-6.53*R2 F +0.2775*RET+0.902*H R -9.10*R2 D (1)

[0018] In formula (1), 850≤K≤851, FET C is the calculated value of the finish rolling entry temperature of the intermediate blank, W is the target width of the finished product, R2 F is the number of rolling passes of the R2 rough rolling mill, RET is the detected value of the furnace post descaling exit slab temperature, H R is the set value of the intermediate blank thickness, R2 D is the number of descaling passes of the R2 rough rolling mill, W, H R All units are mm, FET C and RET are all in ℃, R2 F , R2 D The unit is pass.

[0019] The formula (1) is reported, K=850.7.

[0020] In the rough rolling process, before rough rolling, the initial default rough rolling mills R1 and R2 use 3 passes of rolling, and 1, 3 passes of descaling are used for the R1 and R2 entry and exit descaling, when the finish rolling entry temperature deviation △t (△t=FET C -FET t ) satisfies 10℃≤△t<20℃, on the basis of using the default rolling passes and descaling passes, the two rough rolling mills increase 2 passes of descaling; when 20℃≤△t<30℃, on the basis of using the default rolling passes and descaling passes, the two rough rolling mills increase 2 passes of descaling; when △t≥30℃, the rough rolling mill R1 uses the default rolling passes and descaling passes, and the rough rolling mill R2 uses 5 passes of rolling and all passes are put into descaling; when △t<10℃, the two rough rolling mills use the default rolling passes and descaling passes.

[0021] In the finish rolling process, the finish rolling entry target temperature FET t is determined according to the steel plate finished product thickness h: when h<6.0mm, FET t is 1005℃; when 6≤h<10.0mm, FET t is 985℃; when h≥10.0mm, FET t is 970℃.

[0022] In the heating process, the slab heating exit temperature is determined according to the steel plate finished product thickness specification h: when h<6.0mm, the slab heating exit temperature is 1180~1230℃; when 6.0mm≤h<10.0mm, the slab heating exit temperature is 1130~1180℃; when h≥10.0mm, the heating exit temperature is 1090~1140℃.

[0023] In the embodiment: the production process cast blank successively passes through heating, furnace post descaling, rough rolling, finish rolling, cooling and coiling processes;

[0024] The following equipment is used: a regenerative heating furnace, two rough rolling mills, seven finishing rolling mills, laminar cooling equipment, and an underground coiling machine.

[0025] The cast blank has a thickness of 230 mm and a width of 1850 mm. The mass percentage content of each component of the cast blank is as follows: C: 0.07% to 0.10%; Mn: 0.70% to 1.70%; S: ≤0.005%; P: ≤0.012%; Si: 0.05% to 0.20%; Als: 0.025% to 0.050%; N: ≤0.005%; Nb+Ti+Cr: ≤0.15%; and the remainder is Fe and unavoidable impurities.

[0026] The processes of each procedure are as follows:

[0027] ① Heating procedure: the cast blank is heated to the tapping temperature according to Table 1.

[0028] ② Post-furnace descaling procedure: two rows of descaling headers are used for post-furnace descaling, and the descaling pressure is ≥23 MPa. After the cast blank is descaled of the iron oxide scale after heating, the slab temperature is detected by a pyrometer at the post-furnace descaling outlet, and the highest temperature detected is taken as the post-furnace descaling outlet slab temperature detection value (RET). At the same time, the finishing rolling inlet temperature calculation value (FET C ) is calculated. C The finishing rolling inlet target temperature (FET t ) is determined by Formula 1 below, and is obtained with reference to Table 1. On the basis of the default use of 3 passes of rolling in the rough rolling procedure R1 and R2 and the default use of 1 and 3 passes of descaling at the R1 and R2 inlet and outlet, the actual input mode of the rough rolling procedure is determined according to the following logical judgment: when the finishing rolling inlet temperature deviation Δt (Δt = FET C -FET t ) satisfies 10℃≤△t<20℃, the two rough rolling mills increase the input of 2 passes of descaling on the basis of the default use of rolling passes and descaling passes; when 20℃≤△t<30℃, the two rough rolling mills increase the input of 2 passes of descaling on the basis of the default use of rolling passes and descaling passes; when △t≥30℃, the rough rolling mill R1 uses the default rolling passes and descaling passes, and the rough rolling mill R2 uses 5 passes of rolling and all of the passes are input with descaling; when △t<10℃, the two rough rolling mills use the default rolling passes and descaling passes.

[0029] FET C = K - 0.0804*W - 6.53*R2 F + 0.2775*RET + 0.902*H R - 9.10*R2 D (1)

[0030] In formula 1, 850≤K≤851, FET C is a calculated value of the finishing mill entry temperature, W is a target width of the finished product, and R2 F is the number of rolling passes of the R2 rough rolling mill, RET is a detected value of the furnace post descaling exit slab temperature, and H R is a set value of the intermediate slab thickness, and R2 D is the number of descaling passes of the R2 rough rolling mill, W and H R all units are mm, and FET C all units are ℃, and RET F , R2 D The unit is pass.

[0031] 3. Rough rolling process: the slab is rolled into 40-56 mm intermediate slab according to the determined rolling passes and descaling passes.

[0032] 4. Finishing rolling process: the intermediate slab is rolled into a finished product thickness strip according to the final rolling temperature system in Table 1.

[0033] 5. Cooling and coiling process: the final hot-rolled product strip is obtained according to the cooling system in Table 1 and is coiled into a coil.

[0034] The application will be further described in detail below in combination with specific embodiments.

[0035] Embodiments 1-12

[0036] Embodiments 1-12 are produced according to the above-described embodiments, Table 1 is a hot rolling process parameter table, and Table 2 is a hot rolling process parameter and rough rolling actual rolling descaling pass usage of the embodiments.

[0037] Table 1 Hot rolling process parameter table

[0038]

[0039] Table 2 Hot rolling process parameter and rough rolling actual rolling descaling pass usage of the embodiments

[0040]

[0041] The above embodiments are only used to illustrate but not to limit the technical solutions of the application. Although the application is described in detail with reference to the above embodiments, those skilled in the art should understand that the application can still be modified or equivalently replaced without departing from the spirit and scope of the application, and any modification or partial replacement should be covered in the scope of the claims of the application.

Claims

1. A control method for improving the surface quality of hot-rolled wheel steels, characterized in that: By predicting the intermediate rolled piece finishing rolling inlet temperature in advance, through dynamic adjustment of rough rolling descaling pass and rolling pass, the manual intervention rough rolling descaling pass and rolling pass mode is changed into automatic control mode; the heating, post-furnace descaling, rough rolling, finishing rolling and cooling coiling processes of the slab are included, the intermediate slab finishing rolling inlet temperature calculation value FET is judged in advance after the post-furnace descaling process is completed C , FET C is determined by the following formula (1); FET C = K - 0.0804*W - 6.53*R2 F + 0.2775*RET + 0.902*H R - 9.10*R2 D (1) In formula (1), 850≤K≤851, W is the target width of the finished product, R2 F is the number of passes of the R2 rough rolling mill, RET is the detected value of the slab temperature at the outlet of the descaling after the furnace, H R is the set value of the intermediate slab thickness, R2 D is the number of descaling passes of the R2 rough rolling mill, W, H R all units are mm, FET C and RET all units are ℃, R2 F , R2 D units are passes; In the rough rolling process, before rough rolling opening, the initial default rough rolling mills R1 and R2 use 3 passes, R1 and R2 use 1, 3 passes for descaling at the inlet and outlet, and the precision rolling inlet temperature deviation Δt=FET C -FET t , FET t is the precision rolling inlet target temperature, when Δt satisfies 10℃≤Δt<20℃, on the basis of using the default rolling passes and descaling passes, R2 increases 2 passes of descaling; when 20℃≤Δt<30℃, on the basis of using the default rolling passes and descaling passes, R1 and R2 increase 2 passes of descaling; when Δt≥30℃, the rough rolling mill R1 uses the default rolling passes and descaling passes, R2 uses 5 passes of rolling and all the passes are put into descaling; when Δt<10℃, the two rough rolling mills use the default rolling passes and descaling passes.

2. A method of improving the surface quality of hot-rolled wheel steel according to claim 1, characterized in that: The formula (1), K=850.

7.

3. The method for improving the surface quality of hot-rolled wheel steel according to claim 1, characterized in that : In the finish rolling process, a finish rolling inlet target temperature FET t is determined according to the finished thickness h of the steel sheet: when h < 6.0 mm, FET t is 1005°C; when 6 mm ≤ h < 10.0 mm, FET t is 985°C; and when h ≥ 10.0 mm, FET t is 970°C.

4. The method for improving the surface quality of hot-rolled wheel steel according to claim 1, characterized in that In the heating process, the slab heating temperature is determined according to the thickness h of the finished steel plate: when h<6.0mm, the slab heating temperature is 1180-1230℃; when 6.0mm≤h<10.0mm, the slab heating temperature is 1130-1180℃; when h≥10.0mm, the slab heating temperature is 1090-1140℃.

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