Automatic control method for oxygen spot defects of pickling plates

Abstract

The present application relates to a kind of acid washing plate oxygen spot defect automatic control method, the control method includes the following steps: step 1: when billet is extracted heating furnace, automatically trigger process computer to identify oxygen spot sensitive steel grade, step 2: when oxygen spot sensitive billet is extracted heating furnace, process control computer automatically calls oxygen spot automatic control rule base, and triggers rough rolling each pass automatic speed reduction, step 3: when oxygen spot sensitive billet is rolled, carry out oxygen spot automatic blocking judgment, step 4: quality inspection personnel according to oxygen spot automatic blocking situation, to corresponding steel coil is carried out oxygen spot degradation disposal, avoid flowing into downstream user;The scheme is identified as oxygen spot sensitive steel from plate billet production, billet is extracted after high pyrometer is collected and extracted temperature, calculates temperature difference value, and rough rolling speed is automatically controlled by finished product thickness and temperature difference to reach control rough rolling outlet temperature, reduce oxygen spot occurrence rate.

Description

Technical Field

[0001] The invention relates to a control method, in particular to an automatic control method for oxygen spot defects in a pickling plate, and belongs to the technical field of metallurgy. Background Art

[0002] Oxygen spot in pickled steel is a prominent defect in hot-rolled pickled steel. Oxygen spot is caused by a thick layer of iron oxide on the strip's surface, making it difficult to remove scale. After pickling, the strip's surface is indented with iron scale resembling a "landscape painting." Current hot-rolling control technology primarily ensures quality by controlling the tapping temperature. However, in production environments with tight inventory, steel grades frequently change, and rolling schedules vary widely, making it very easy for the actual tapping temperature to be significantly higher. On-site production and quality control are often performed only through post-rolling checks, which can easily lead to the appearance of oxygen spot in pickled batches, resulting in batch quality incidents.

[0003] In response to similar situations, various manufacturers and research institutions have done a lot of work. Chinese patent application CN201711393932.7, "A Pickled Plate (Coil) for Stamping and Manufacturing Method," uses the ESP process to produce deep-drawn pickled plates. Chinese patent application CN201310489332.6, "A Method for Producing Hot-Rolled Pickle-Free Plates by Combining Thin Strip Continuous Casting with Reduction Annealing," proposes a method for producing hot-rolled pickle-free plates by combining thin strip continuous casting with reduction annealing. Chinese patent application CN201110086611.9, "A Thin Slab Continuous Casting and Rolling Line for Producing Steel Plates for Enameled Water Heater Liners and Method," proposes a method and process for producing hot-rolled pickled steel plates for enameled water heater liner on a FTSR thin slab continuous casting and rolling line. However, none of the existing technologies have solved the above problems. Summary of the Invention

[0004] The present invention is aimed at the problems existing in the prior art and provides an automatic control method for oxygen spot defects in pickled plates. This technical solution is an automatic control system that controls the speed of the roughing mill to reduce the roughing outlet temperature when the temperature changes greatly, slows down the reaction rate of the iron oxide scale, reduces the blockage of oxygen spots, and automatically blocks and degrades the quality when the temperature changes exceed the risk temperature threshold.

[0005] In order to achieve the above object, the technical solution of the present invention is as follows: a method for automatically controlling oxygen spot defects in pickling plates, the control method comprising the following steps:

[0006] Step 1: When the billet is taken out of the heating furnace, the process computer is automatically triggered to identify the steel grade that is sensitive to oxygen spots. If it is an oxygen spot sensitive steel grade, the following physical quantities corresponding to this piece of steel are recorded:

[0007] 1) Identify whether there is an oxygen spot marker signal Y;

[0008] 2) Target oven temperature T0, in °C;

[0009] 3) Actual tapping temperature T, unit ℃;

[0010] 4) Steel billet target rolling thickness h, unit mm;

[0011] 5) Steel billet tapping temperature difference ΔT;

[0012] 6) Actual rough rolling exit temperature RDT, unit ℃;

[0013] 7) Rough rolling exit temperature corresponding quality risk level: high, low, see table 1;

[0014] If it is a non-oxygen spot sensitive steel, it is automatically not controlled.

[0015] Step 2, after the oxygen spot sensitive steel billet is drawn out of the heating furnace, the process control computer automatically calls the oxygen spot automatic control rule base, and triggers the rough rolling automatic speed reduction of each pass, and the speed reduction value of each pass is calculated as follows:

[0016] ΔV = λ·(T-T0)

[0017] Wherein, ΔV is the speed reduction value of each pass of rough rolling, and the upper limit of ΔV is 0.8 m / s; λ is the temperature speed conversion coefficient, and λ is 0.025.

[0018] Step 3, after the oxygen spot sensitive steel billet is rolled, oxygen spot automatic blocking judgment is carried out, if T-T0> α, α is the oxygen spot risk temperature threshold, when h≥4.0mm, α is generally 40℃; When h<4.0mm, α is generally 45℃, the threshold is obtained by offline regression of the data of the oxygen spot defect coil and the hot rolling temperature after pickling in the next process within a certain time range.

[0019] Step 4, the quality inspection personnel carries out oxygen spot degradation disposal on the corresponding steel coil according to the oxygen spot automatic blocking situation, so as to avoid flowing into the downstream user.

[0020] Compared with the prior art, the present application has the following advantages, the scheme is identified as oxygen spot sensitive steel after the production of the slab, the tapping temperature is collected by pyrometer after the steel billet is tapped, the temperature difference value is calculated, the rough rolling speed is automatically controlled through the thickness of the finished product and the temperature difference to control the rough rolling exit temperature, reduce the oxygen spot occurrence rate, at the same time, the computer L3 system automatically carries out quality risk identification and makes quality risk level judgment by comparing the temperature difference between the actual rough rolling exit temperature and the target temperature, the quality inspection personnel makes quality disposal according to the judgment result of L3 system to avoid causing quality coil to flow out. After testing, the oxygen spot defect does not appear in large quantities, and the product quality is further improved. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 It is a process schematic diagram of step 1;

[0022] Figure 2 This is a schematic diagram of the process of step 2;

[0023] Figure 3 This is a schematic diagram of the process of step 3;

[0024] Figure 4 This is a schematic diagram of the process of step 4;

[0025] Figure 5 Schematic diagram of the entire control process. DETAILED DESCRIPTION

[0026] In order to deepen the understanding of the present invention, this embodiment is described in detail below with reference to the accompanying drawings.

[0027] Example 1: See Figure 1 , a method for automatically controlling oxygen spot defects on pickling plates, the control method comprising the following steps:

[0028] Step 1: When the billet is taken out of the heating furnace, the process computer is automatically triggered to identify the steel grade that is sensitive to oxygen spots. If it is an oxygen spot sensitive steel grade, the following physical quantities corresponding to this piece of steel are recorded:

[0029] 1) Identify whether there is an oxygen spot marker signal Y;

[0030] 2) Target oven temperature T0, in °C;

[0031] 3) Actual oven temperature T, unit: °C;

[0032] 4) Target rolling thickness of steel billet h, in mm.

[0033] 5) Temperature difference ΔT of the billet out of the furnace.

[0034] 6) Actual rough rolling outlet temperature RDT, unit: °C;

[0035] 7) Rough rolling outlet temperature corresponding to quality risk level: high, low (Table 1)

[0036] Table 1. Quality risk level corresponding to rough rolling outlet temperature

[0037]

[0038] If the steel is not sensitive to oxygen spots, no control will be performed automatically.

[0039] Step 2: When the steel billet sensitive to oxygen spots is taken out of the heating furnace, the process control computer automatically calls the oxygen spot automatic control rule library.

[0040] And trigger the automatic speed reduction of each rough rolling pass. The speed reduction value of each pass is calculated as follows:

[0041] ΔV=λ·(T-T0)

[0042] Among them, ΔV is the speed reduction value of each rough rolling pass, and the upper limit of ΔV is 0.8m / s; λ is the temperature-speed conversion coefficient, and λ is 0.025.

[0043] Step 3: After the rolling of the oxygen spot-sensitive steel billet is completed, the oxygen spot automatic blocking judgment is performed. If T-T0>α, α is the oxygen spot risk temperature threshold. When h≥4.0mm, α is generally 40°C; when h<4.0mm, α is generally 45°C. This threshold is obtained by offline regression of the oxygen spot defect coil after pickling in the next process and the hot rolling temperature data within a certain time range.

[0044] Step 4: Quality inspectors will downgrade the corresponding steel coils according to the automatic blocking of oxygen spots to prevent them from flowing into downstream users.

[0045] Specific embodiment: see Figure 1 , a method for automatically controlling oxygen spot defects on pickling plates, the control method comprising the following steps:

[0046] Step 1: Create an oxygen spot mark in the contract management system, and specify in the system that steel grades prone to oxygen spots, such as AP0941D1 and AP0640B8, will have this mark. The slabs will have the mark issued by the contract management system.

[0047] The production system receives oxygen spot marks when receiving information from the contract management system. When the billet is pulled out of the heating furnace, the computer automatically identifies and determines the oxygen spot coil based on the oxygen spot marks. If it determines that the steel is oxygen spot sensitive, it will record the following physical quantities corresponding to the steel:

[0048] 1) Identify whether there is an oxygen spot marker signal Y;

[0049] 2) Target furnace temperature T0;

[0050] 3) Actual oven temperature T;

[0051] 4) Target rolling thickness of steel billet h;

[0052] 5) Billet out-of-furnace temperature difference ΔT;

[0053] 6) Actual rough rolling outlet temperature RDT, unit: °C;

[0054] 7) Oxygen spot quality risk level corresponding to rough rolling outlet temperature: high, low

[0055] Step 2: The key factor in controlling oxygen spots is the rough rolling outlet temperature control. Based on different furnace temperature ranges and rough rolling outlet temperature control requirements, the required rough rolling temperature control value is calculated. Combined with the basic rough rolling temperature drop values ​​under different thicknesses and speeds, the model automatically allocates and calculates the required control temperatures and respective speed reduction values ​​for the six rough rolling passes. When the oxygen spot-sensitive billet is withdrawn from the heating furnace, the process control computer calculates the rough rolling temperature control value and automatically calculates and issues the speed reduction value for each rough rolling pass. The speed reduction value for each pass is calculated as follows:

[0056] ΔV=λ·(T-T0)=0.025(m / s) / ℃*(1250-1200)℃

[0057] Since the upper limit of ΔV is 0.8m / s, the speed reduction value ΔV for each pass of rough rolling of this steel is taken as 0.8m / s.

[0058] Step 3: After the rolling of the oxygen spot sensitive billet is completed, the quality control system L3 is divided into two levels and methods according to the heating furnace temperature:

[0059] If h≥4.0mm, ΔT>40℃ or h<4.0mm, ΔT>45℃, it is judged as "high risk of oxygen spot" and the annotation is automatically blocked;

[0060] If h ≥ 4.0 mm, 20°C < ΔT ≤ 40°C or h < 4.0 mm, 0°C < ΔT ≤ 45°C, it is judged as "low risk of oxygen spots" and the annotation is automatically blocked;

[0061] If the T-T0 value is ≤20℃, no judgment is made and no automatic blocking is performed.

[0062] Step 4: The L3 computer automatically determines the oxygen spot quality risk level corresponding to the rough rolling outlet temperature of the steel coil with high oxygen spot risk. The quality inspection personnel dispose of the steel coil based on the information determined by the L3 system to prevent it from flowing into downstream users.

[0063] Example 1: Specification rolling method

[0064] Taking h=4.5mm steel grade AP0941D as an example: T0=1200℃, when h≥4.0mm, the oxygen spot risk temperature threshold value α is 40℃

[0065] Step 1: Create an oxygen spot mark in the contract management system and automatically identify the oxygen spot mark of steel grade AP0941D as "Y";

[0066] 2. The target furnace temperature T0 is 1200℃;

[0067] 3. Target rolling thickness of billet h = 4.5 mm;

[0068] 4. After the billet comes out of the furnace, the pyrometer measures the actual furnace temperature T;

[0069] 5. Billet out-of-furnace temperature difference ΔT = T-T0

[0070] 6. Actual rough rolling outlet temperature RDT, unit: °C;

[0071] 7. Rough rolling outlet temperature corresponding to quality risk level: high, low

[0072] Specific Example 1: The actual furnace temperature T measured by the pyrometer is 1205°C;

[0073] Step 2: 1. ΔT = 1205 - 1200 = 5°C, ΔT ≤ 20°C;

[0074] 2. The control function of the roughing mill is not triggered;

[0075] Step 3: The quality blocking system does not automatically block.

[0076] Step 4: Automatically determine whether the surface oxygen spots are of qualified quality.

[0077] Specific Example 2: The actual furnace temperature T measured by the pyrometer is 1235°C;

[0078] Step 2: 1. ΔT = 1235-1200 = 35°C, ΔT > 20°C;

[0079] 2. Trigger the roughing mill control function, and the roughing mill speed reduction ΔV = λ·(T-T0) = 0.025(m / s) / ℃*(1235-1200)℃ = 0.875m / s. Since the upper limit of ΔV is 0.8m / s, the speed reduction value ΔV of each pass of rough rolling of this steel is taken as 0.8m / s.

[0080] Step 3: The quality blocking system automatically blocks and annotates "low risk of oxygen spots".

[0081] Step 4: The quality inspector determines whether the surface oxygen spots are of qualified quality based on the automatic blocking.

[0082] Specific Example 3: The actual furnace temperature T measured by the pyrometer is 1243°C;

[0083] Step 2: 1. ΔT = 1243 - 1200 = 43°C, ΔT > 40°C;

[0084] 2. Trigger the roughing mill control function. The roughing mill speed reduction ΔV = λ·(T-T0) = 0.025(m / s) / °C*(1243-1200)°C = 1.075m / s. Since the upper limit of ΔV is 0.8m / s, the speed reduction value ΔV for each pass of rough rolling of this steel is 0.8m / s.

[0085] Step 3: The quality blocking system automatically blocks the sample and annotates it as "high risk of oxygen spots";

[0086] Step 4: The L3 computer automatically determines the oxygen spot quality risk level of the steel coil with high oxygen spot risk based on the actual temperature at the rough rolling outlet. See Table 1. Since the actual temperature at the rough rolling outlet is 1055℃, the oxygen spot risk level of this steel is "high" and it is directly downgraded.

[0087] Specific embodiment 4: Specification rolling method

[0088] Taking AP0640B8 steel with h = 3.0 mm as an example: T0 = 1200°C, h < 4.0 mm, and the oxygen spot risk temperature threshold value α is 45°C. It should be noted that the above embodiments are not intended to limit the scope of protection of the present invention, and equivalent modifications or substitutions based on the above technical solutions fall within the scope of protection of the claims of the present invention.

Claims

1. A method for automatically controlling oxygen spot defects on pickled plates, characterized in that: The control method comprises the following steps: Step 1: When the billet is taken out of the heating furnace, the process control computer is automatically triggered to identify the oxygen spot sensitive steel grade. Step 2: When the billet sensitive to oxygen spots is taken out of the heating furnace, the process control computer automatically calls the oxygen spot automatic control rule library and triggers the automatic speed reduction of each rough rolling pass. Step 3: After the rolling of the oxygen spot sensitive billet is completed, the oxygen spot automatic blocking judgment is performed. Step 4: Quality inspectors will downgrade the corresponding steel coils based on the automatic blocking of oxygen spots to prevent them from flowing into downstream users. In step 1, when the steel billet is pulled out of the heating furnace, the process control computer is automatically triggered to identify the steel grade that is sensitive to oxygen spots. If it is an oxygen spot sensitive steel grade, the following physical quantities corresponding to this piece of steel are recorded: 1) Identify whether there is an oxygen spot marker signal Y; 2) Target oven temperature T0, in °C; 3) Actual oven temperature T, unit: °C; 4) Target rolling thickness of the billet h, in mm; 5) Billet out-of-furnace temperature difference ΔT; 6) Actual rough rolling outlet temperature RDT, unit: °C; 7) Rough rolling outlet temperature corresponding to quality risk level: high, low; If the steel is not sensitive to oxygen spots, it will not be controlled automatically; Step 2: When the oxygen spot-sensitive billet is withdrawn from the heating furnace, the process control computer automatically calls the oxygen spot automatic control rule library and triggers the automatic speed reduction of each rough rolling pass. The speed reduction value of each pass is calculated as follows: ΔV=λ·(T-T0) Among them, ΔV is the speed reduction value of each rough rolling pass, and the upper limit of ΔV is 0.8m / s; λ is the temperature-speed conversion coefficient, λ is 0.025; Step 3: After the rolling of the oxygen spot-sensitive billet is completed, the oxygen spot automatic blocking judgment is performed. If T-T0>α, α is the oxygen spot risk temperature threshold. When h≥4.0mm, α is 40°C; when h<4.0mm, α is 45°C. This threshold is obtained by offline regression of the oxygen spot defect coils after pickling in the next process and the hot rolling temperature data within a certain time range; Step 3: After the rolling of the oxygen spot sensitive billet is completed, the quality control system L3 is divided into two levels and methods according to the heating furnace temperature: If h≥4.0mm, ΔT>40℃ or h<4.0mm, ΔT>45℃, it is judged as "high risk of oxygen spot" and the annotation is automatically blocked; If h≥4.0mm, 20℃<ΔT≤40℃ or h<4.0mm, 0℃<ΔT≤45℃, it is judged as "low risk of oxygen spot" and the annotation is automatically blocked; If the T-T0 value is ≤20℃, no judgment is made and no automatic blocking is performed.

Images