Thermal analysis carbon control method for gray cast iron

Abstract

The present application relates to the technical field of steel smelting, and particularly relates to a hot analysis carbon control method for gray cast iron. The method comprises the following steps: judging the composition uniformity of the scrap steel to be added and precalculating the purifying material; determining whether to start the hot analysis based on whether the silicon content of the molten iron is in the effective interval, and judging the eutectic undercooling phenomenon by identifying the slope of the cooling curve to calculate the actual carbon content; determining whether to add the carbon additive or the scrap steel and the matching purifying material according to the comparison result of the actual carbon content and the target carbon content; second sampling the molten iron after the regulation and control, and determining whether the regulation and control and the purification are up to the standard according to the carbon content deviation and the impurity residual amount; when the regulation and control and the purification are not up to the standard, inversely calculating the actual absorption rate of the carbon additive, the actual effective carbon content of the scrap steel and the purification efficiency; and respectively optimizing the adding amount of the carbon additive and the scrap steel and the adding amount of the purifying material matched with the scrap steel based on the inverse calculation result. The present application solves the problems of poor timeliness, low precision and complex operation in the carbon content control of the gray cast iron.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of steel smelting, and particularly relates to a thermal analysis carbon control method for gray cast iron. BACKGROUND

[0002] In the production of gray cast iron, the carbon content of molten iron is a core parameter for determining the mechanical properties and quality of castings. The carbon content in gray iron castings has a significant impact on their performance and quality. Therefore, rapid and accurate regulation and control of the carbon content of molten iron is a key link to ensure stable casting quality, reduce production costs, and improve production efficiency. At present, the detection and control of the carbon content of molten iron in the industry mainly rely on the following existing technologies:

[0003] Spectral detection method: the characteristic spectrum of the molten iron sample is excited to analyze the element content. Although this method has a faster analysis speed, it highly depends on the standard sample with highly matched composition for calibration. In actual production, the composition of cast iron is variable, and it is difficult to ensure that the standard sample completely covers all cases, resulting in systematic measurement deviation. In addition, the sample preparation requirements are extremely harsh, and the carbon element must be white and uniform, which may cause measurement deviation.

[0004] Carbon and sulfur instrument detection method: it is used for detecting carbon and sulfur elements, but its operation environment requires strictness, and it needs to run in a constant temperature, specific carrier gas flow and pure oxygen environment, which limits the convenience of on-site operation. Similarly, its analysis results are also affected by sample uniformity and representativeness.

[0005] Chemical analysis method: as a traditional laboratory method, it is considered as a reference method with high precision, but the analysis period is too long, and there is serious lag, which cannot provide decision basis for immediate composition adjustment of smelting site, and can only be used for post verification, and cannot meet the real-time requirement of process control for modern production line.

[0006] Chinese patent publication No. CN103399529A discloses a molten iron composition carbon content computer control method. The control method comprises: detecting the carbon content of molten iron composition by a carbon and sulfur detector; an SPC system responds to the detection data of the carbon content of molten iron composition and displays in the form of a control chart; and the detection data of the carbon content of molten iron composition is dynamically monitored by using the control chart. The molten iron composition carbon content computer control method directly transmits the data of the carbon and sulfur detector to the SPC system of the computer, saves the step operation of manual data recording, effectively improves the efficiency, reduces the human error, and displays the data entering the SPC system by using the control chart. According to the principle of the control chart, the data with abnormality or abnormal trend is alarmed, and the functions of real-time monitoring and early warning are achieved.

[0007] Therefore, it can be seen that the computer control method for carbon content in molten iron has problems such as poor timeliness and low precision in controlling carbon content in molten iron, and poor finished product quality due to untimely adjustment of carbon content caused by complex operation. Summary of the Invention

[0008] Therefore, the present invention provides a method for controlling carbon content in the thermal analysis of gray cast iron, which overcomes the problems of poor timeliness, low accuracy and complicated operation in the existing technology for controlling carbon content in molten iron.

[0009] To achieve the above objectives, this invention provides a method for controlling carbon content in thermal analysis of gray cast iron. It includes:

[0010] Prepare the carbon raiser and the scrap steel to be added. Determine whether the scrap steel meets the conditions for addition by detecting the carbon content range in the scrap steel to be added. Calculate the amount of purification material to be added based on the content of key impurity elements.

[0011] Samples of gray cast iron were taken from the smelting furnace. Based on the fact that the silicon content in the sampled iron was within the preset thermal analysis silicon content range, thermal analysis was performed on the sampled iron to obtain the instantaneous slope during the eutectic reaction, in order to determine whether eutectic supercooling occurred, and to determine the carbon equivalent and actual carbon content of the sampled iron.

[0012] Based on the actual carbon content, determine the addition of a carbon raiser, scrap steel, and purification materials that are compatible with the scrap steel to the molten gray cast iron in the smelting furnace;

[0013] To obtain the actual carbon content and residual amount of key impurities after adding carbon raisers and scrap steel;

[0014] When the control of the gray cast iron in the smelting furnace is deemed unqualified based on the determination result that the absolute deviation between the actual carbon content after adjustment and the target carbon content is greater than the preset absolute deviation value, the actual absorption rate of the single carbon additive and the actual effective carbon content of the scrap steel are obtained. When the residual amount is greater than the preset residual amount, it is determined that the purification effect is not up to standard, and the actual purification efficiency of the purified material is obtained.

[0015] Under the condition of unqualified regulation, the amount of carbon refining agent and the amount of scrap steel added are adjusted according to the actual absorption rate of the carbon refining agent and the actual effective carbon content of the scrap steel.

[0016] Under the condition that the purification does not meet the standards, the amount of purification material to be added for the scrap steel is adjusted according to the actual purification efficiency.

[0017] Based on the optimized amounts of carbon raiser, scrap steel, and purified materials, precise control of the carbon content in molten iron is achieved.

[0018] Further, the process of determining whether it is necessary to match a purification material for the scrap steel to be added and calculating the addition amount of the required purification material includes

[0019] sampling the scrap steel to be added;

[0020] obtaining the content of key impurity elements in the sampled scrap steel;

[0021] comparing the content of the key impurity elements with a preset content;

[0022] Based on the content of the key impurity elements being greater than the preset content, it is determined that it is necessary to match a purification material for the scrap steel to be added and calculate the preset addition amount of the purification material;

[0023] Among them, the content of the key impurity elements is the content of phosphorus element and sulfur element.

[0024] Further, the process of determining whether eutectic undercooling occurs and calculating the carbon equivalent and the actual carbon content of the sampled molten iron through corresponding calculation strategies includes

[0025] obtaining the primary crystallization temperature and the eutectic temperature during the thermal analysis of the sampled molten iron;

[0026] obtaining the cooling curve of the sampled molten iron and calculating the temperature change rate per unit time within the eutectic temperature platform interval to obtain the instantaneous slope;

[0027] comparing the absolute value of the instantaneous slope with the absolute value of a preset instantaneous slope;

[0028] Based on the absolute value of the instantaneous slope being less than or equal to the absolute value of the preset instantaneous slope, it is determined that eutectic undercooling does not occur, and the carbon equivalent and the actual carbon content are calculated using the first regression equation.

[0029] Further, the process of determining whether eutectic undercooling occurs and calculating the carbon equivalent and the actual carbon content of the sampled molten iron through corresponding calculation strategies further includes

[0030] Based on the absolute value of the instantaneous slope being greater than the absolute value of the preset instantaneous slope, it is determined that eutectic undercooling occurs, and after compensating the eutectic temperature, the first regression equation is used to calculate the carbon equivalent and the actual carbon content.

[0031] Further, the process of determining the addition of a carbon increasing agent, scrap steel, and a purification material配套 with the scrap steel to the gray cast iron molten iron in the melting furnace according to the actual carbon content includes

[0032] obtaining the actual carbon content;

[0033] comparing the actual carbon content with the target carbon content;

[0034] Based on the fact that the actual carbon content is less than the target carbon content, it is determined that the actual carbon content in the sampled molten iron is insufficient, and a carbon raiser is added to the smelting furnace.

[0035] Furthermore, the process of determining the addition of a carbon raiser, scrap steel, and corresponding purification materials to the molten gray cast iron in the smelting furnace based on the actual carbon content also includes,

[0036] Based on the fact that the actual carbon content is greater than the target carbon content, it is determined that the actual carbon content in the sampled molten iron is excessive. At this point, scrap steel and purification materials that are compatible with the scrap steel are added to the smelting furnace.

[0037] Furthermore, the process of optimizing the amount of carbon raiser added based on its actual absorption rate includes,

[0038] The actual absorption rate of the carbon additive is compared with the target absorption rate of the carbon additive;

[0039] Since the actual absorption rate of the carbon additive is less than the target carbon additive absorption rate, it is determined to reduce the preset carbon additive absorption rate. The reduction is positively correlated with the deviation between the actual absorption rate and the target carbon additive absorption rate, so as to increase the amount of carbon additive added.

[0040] Based on the fact that the actual absorption rate of the carbon additive is greater than the target absorption rate, the carbon additive absorption rate is increased by a predetermined amount. The increase is positively correlated with the deviation between the actual absorption rate and the target absorption rate, so as to reduce the amount of carbon additive added.

[0041] Furthermore, the process of optimizing the amount of scrap steel added based on its actual effective carbon content includes,

[0042] The actual effective carbon content of the scrap steel is compared with the carbon content of the target scrap steel;

[0043] Based on the fact that the actual effective carbon content of the scrap steel is less than the target carbon content of the scrap steel, the carbon content of the pre-set scrap steel is reduced. The reduction range is positively correlated with the deviation between the actual effective carbon content of the scrap steel and the target carbon content of the scrap steel, so as to reduce the amount of scrap steel added.

[0044] The carbon content of the scrap steel is increased based on the fact that the actual effective carbon content of the scrap steel is greater than the target carbon content of the scrap steel. The increase is positively correlated with the deviation between the actual effective carbon content of the scrap steel and the target carbon content of the scrap steel, so as to increase the amount of scrap steel added.

[0045] Furthermore, the process of optimizing the amount of purification material to be added based on the actual purification efficiency includes,

[0046] To obtain the residual amount of impurities in the molten iron from the second sampling and the impurity content in the molten iron before regulation;

[0047] Obtain the expected total amount of impurities in the added scrap steel, and calculate the difference between the expected total amount of impurities and the residual amount and the impurity content to obtain the actual amount removed.

[0048] The actual purification efficiency is obtained by calculating the ratio of the actual amount removed to the expected total amount of impurities.

[0049] The actual purification efficiency is compared with the target purification efficiency;

[0050] Based on the fact that the actual purification efficiency is less than the target purification efficiency, the preset purification efficiency coefficient is adjusted to be lowered. The adjustment range is positively correlated with the efficiency deviation between the actual purification efficiency and the target purification efficiency, so as to increase the amount of purification material added.

[0051] Furthermore, the process of optimizing the amount of purification material to be added based on the actual purification efficiency also includes,

[0052] Based on the fact that the actual purification efficiency is greater than the target purification efficiency, the preset purification efficiency coefficient is increased. The increase is positively correlated with the efficiency deviation between the actual purification efficiency and the target purification efficiency, so as to reduce the amount of purification material added.

[0053] Compared with existing technologies, the beneficial effects of this invention are as follows: This invention achieves precise control of the entire process from raw materials to finished products through the determination of scrap steel composition uniformity and pre-setting of purified materials, thermal analysis access based on silicon content range and intelligent supercooling treatment, carbon increase / scrap steel decision based on quantitative model and simultaneous addition of corresponding purified materials, dual index verification of carbon content and purity and back calculation of key parameters, and dual closed-loop self-optimization of carbon increase / scrap steel / purified material strategies. It completely replaces the fuzzy control that relies on worker experience, ensures that the composition of molten iron can stably hit the demanding target window, improves the first pass rate, reduces rework and scrap, optimizes raw material consumption, and brings significant economic benefits. It is a key technological breakthrough for promoting the intelligent and green transformation and upgrading of the foundry industry.

[0054] Furthermore, this invention objectively determines the batch uniformity of scrap steel by detecting the carbon content range, and calculates the preset addition amount of purification material based on the sulfur and phosphorus content. This ensures that when carbon reduction control is performed in subsequent steps, the purification agent can be added synchronously according to the calculated amount of purification material required per unit mass of scrap steel, thereby actively neutralizing the impurities introduced by the scrap steel. This achieves a synergy between carbon reduction and purity maintenance, laying a purity foundation for the production of high-quality castings.

[0055] Furthermore, this invention intelligently diagnoses eutectic overcooling by calculating the instantaneous slope of the cooling curve during the eutectic reaction, and accordingly activates different calculation strategies: the first calculation strategy is used when there is no overcooling, and the second calculation strategy is activated when there is overcooling. This effectively avoids misjudgment of carbon content caused by distortion of the cooling curve, and provides a solid and reliable data foundation for all subsequent control decisions.

[0056] Furthermore, this invention abandons empirical estimation and uses preset carbonizer absorption rate and preset scrap steel carbon content for quantitative calculation. More importantly, in steps S4, S5 and S6, the system back-calculates the actual carbonizer absorption rate, the actual effective carbon content of scrap steel and the actual purification efficiency of the purified material through secondary sampling data, and compares these measured values ​​with the target values. Then, it dynamically optimizes the corresponding model preset parameters according to the positive correlation of the deviation. This closed loop of "execution-verification-back-calculation-optimization" enables the system to adapt to raw material and process fluctuations and achieve continuous self-improvement.

[0057] Furthermore, through the comprehensive application of the aforementioned technical means, this invention ensures the extreme stability of carbon content and purity in molten iron, providing reliable performance and microstructure guarantees for high-end machine tool castings. Simultaneously, the significant increase in first-pass yield, substantial reduction in rework and scrap, and precise calculation and waste avoidance of raw materials such as carbon raisers, scrap steel, and purified materials collectively bring significant economic benefits. This invention represents a data-driven, precisely controllable advanced production model and is a key practice for the foundry industry towards intelligent and green manufacturing. Attached Figure Description

[0058] Figure 1 This is a flowchart illustrating the steps of a thermal analysis carbon control method for gray cast iron according to an embodiment of the present invention.

[0059] Figure 2 This is a logic block diagram illustrating how an embodiment of the present invention determines whether the scrap steel to be added meets the requirements for addition based on the carbon content range.

[0060] Figure 3 This is a logic block diagram illustrating how to determine whether the scrap steel to be added needs to be matched with purified materials based on the content of key impurity elements, according to an embodiment of the present invention.

[0061] Figure 4 This is a logic block diagram illustrating how the present invention determines whether eutectic undercooling occurs based on the instantaneous slope in an embodiment of the invention.

[0062] Figure 5 This is a logic block diagram illustrating how the smelting process of gray cast iron in a smelting furnace is controlled based on the actual carbon content, according to an embodiment of the present invention.

[0063] Figure 6This is a logic block diagram illustrating how the amount of carburizer added is optimized based on the actual absorption rate of the carburizer added to molten iron, according to an embodiment of the present invention.

[0064] Figure 7 This is a logic block diagram illustrating how the amount of scrap steel to be added is optimized based on the actual effective carbon content of the scrap steel in the added scrap steel, according to an embodiment of the present invention.

[0065] Figure 8 This is a logic block diagram illustrating how the amount of purification material to be added to the scrap steel is optimized based on the actual purification efficiency, according to an embodiment of the present invention. Detailed Implementation

[0066] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0067] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0068] It should be noted that in the description of this invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc., which indicate directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and is not intended to indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0069] Please see Figure 1 The diagram shows the steps of a thermal analysis carbon control method for gray cast iron according to an embodiment of the present invention.

[0070] The present invention provides a method for controlling carbon content in thermal analysis of gray cast iron, comprising:

[0071] Step S1: Insert a sample cup into the lower part of the base of the corresponding furnace number and prepare the carbon additive and scrap steel to be added. Detect the carbon content and key impurity element content in the scrap steel to be added, and calculate the carbon content range in the scrap steel to be added. Determine whether the current batch of scrap steel to be added meets the addition conditions based on the carbon content range. If the addition conditions are met, calculate the required amount of purified material to be added based on the phosphorus and sulfur content of the key impurity elements.

[0072] Step S2: After sampling the molten iron in the furnace, the silicon and phosphorus content in the molten iron is detected using a spectrometer. Based on the silicon content in the sampled molten iron being within the preset thermal analysis silicon content range, thermal analysis is performed on the sampled molten iron to obtain the cooling curve of the molten iron and identify the eutectic plateau morphology. Based on the eutectic plateau morphology, it is determined whether eutectic undercooling has occurred. Based on the judgment result, the carbon equivalent and actual carbon content of the sampled molten iron are obtained through a preset corresponding calculation strategy.

[0073] Step S3: After calculating the actual carbon content of the sampled molten iron, determine the addition of a carbon raiser, scrap steel, and purification materials that are compatible with the scrap steel in the gray cast iron molten iron in the smelting furnace based on the comparison between the actual carbon content of the sampled molten iron and the target carbon content.

[0074] Step S4: A second sample is taken from the molten iron in the smelting furnace to obtain the actual carbon content and residual amount of key impurities in the molten iron after adjustment. The carbon content deviation between the actual carbon content and the target carbon content is used to determine whether the adjustment of the gray cast iron in the smelting furnace is qualified. At the same time, the residual amount is used to determine whether the purification effect meets the standard. If the carbon content adjustment is not qualified, the actual absorption rate of the single carbon-raising agent and the actual effective carbon content of the scrap steel are calculated. If the purification effect does not meet the standard, the actual purification efficiency of the purified material is calculated.

[0075] Step S5: Under the condition of unqualified regulation, optimize the regulation strategy for adding carbonizer and adding scrap steel according to the actual absorption rate of the carbonizer and the actual effective carbon content of the scrap steel.

[0076] Step S6: Under the condition that the purification does not meet the standard, the amount of purification material to be added for the scrap steel is optimized based on the efficiency deviation between the actual purification efficiency and the target purification efficiency.

[0077] Specifically, this invention achieves precise, multi-dimensional control of the entire process from raw materials to finished products through the determination of scrap steel composition uniformity and pre-setting of purified materials, thermal analysis access based on silicon content range and intelligent supercooling treatment, carbon increase / scrap steel decision-making based on quantitative models and simultaneous addition of corresponding purified materials, dual-index verification of carbon content and purity and back-calculation of key parameters, and dual closed-loop self-optimization of carbon increase / scrap steel / purified material strategies. This completely replaces the fuzzy control that relies on worker experience, ensuring that the composition of molten iron can stably hit the demanding target window, improving the first-pass yield, reducing rework and scrap, optimizing raw material consumption, and bringing significant economic benefits. It is a key technological breakthrough for promoting the intelligent and green transformation and upgrading of the foundry industry.

[0078] Please see Figure 2 As shown, it is a logic block diagram of an embodiment of the present invention for determining whether the scrap steel to be added meets the requirements for addition based on the carbon content range.

[0079] Specifically, in step S1, samples of the scrap steel to be added are taken, and a mobile spectrometer is used to quickly detect the carbon content, as well as the content of key impurity elements sulfur and phosphorus, in each sample. The arithmetic mean of the sulfur content in all samples is calculated as the average sulfur content of the batch of scrap steel. Simultaneously, the arithmetic mean of the phosphorus content in all samples is calculated as the average phosphorus content of the batch of scrap steel. The difference between the maximum and minimum carbon content in all samples is calculated to obtain the carbon content range. Based on the comparison between the carbon content range of the scrap steel to be added and the preset carbon content range, it is determined whether the current batch of scrap steel to be added meets the requirements for addition.

[0080] If the carbon content range is less than the preset carbon content range, then the scrap steel to be added in the current batch is determined to meet the requirements for addition.

[0081] If the carbon content range is greater than or equal to the preset carbon content range, then the scrap steel to be added in the current batch is determined to be non-compliant with the requirements for addition.

[0082] In this embodiment of the invention, the preset carbon content range is 0.10% to 0.20%, and the preferred value is 0.15%. The preferred range and preferred value can be determined according to the actual situation, and are not specifically limited here.

[0083] Please see Figure 3 As shown, it is a logic block diagram of an embodiment of the present invention for determining whether the scrap steel to be added needs to be matched with purification materials based on the content of key impurity elements.

[0084] Specifically, assuming the current batch of scrap steel to be added meets the requirements, the method determines whether it is necessary to match the scrap steel with purification materials based on the comparison between the content of the key impurity elements and the preset content, and calculates the preset addition amount of the purification materials if necessary.

[0085] If the content of the key impurity element is less than or equal to the preset content, then it is determined that there is no need to match and purify the scrap steel to be added.

[0086] If the content of the key impurity element is greater than the preset content, it is determined that the scrap steel to be added needs to be matched with purified material, and the preset addition amount of the purified material is calculated.

[0087] In this embodiment of the invention, the content of the key impurity elements includes, but is not limited to, the content of sulfur and phosphorus. The preset value range of the sulfur content is 0.05% to 0.12%, and the preferred value in this invention is 0.08%; the preset value range of the phosphorus content is 0.10% to 0.20%, and the preferred value in this invention is 0.15%. The preferred range and preferred value can be determined according to the actual situation, and are not specifically limited here.

[0088] In this embodiment of the invention, the preset addition amount is obtained by first calculating the difference between the content of the key impurity element and the preset content to obtain the unit removal amount, then calculating the product of the unit removal amount and the total mass of the scrap steel to be added to obtain the total amount of impurity elements to be removed, then determining a fixed theoretical mass ratio based on the chemical reaction equation between the purification material to be added and the element to be purified, and calculating the product of the total amount of impurity elements and the fixed theoretical mass ratio to obtain the theoretical demand amount of the purification material. It is worth noting that since the actual reaction process cannot be completely complete, a preset purification efficiency coefficient is set to compensate for the incompleteness of the actual reaction. The ratio of the theoretical demand amount to the preset purification efficiency coefficient is calculated to obtain the actual demand amount of the purification material, and finally the product of the actual demand amount and the safety factor is calculated to obtain the preset addition amount of the purification material.

[0089] The safety factor is a constant greater than 1.

[0090] In this embodiment of the invention, taking desulfurization as an example, the purified material is calcium carbide, and the calculation process for its preset addition amount is as follows: First, calculate the difference between the sulfur element content and its preset content to obtain the amount of sulfur removed from a unit of scrap steel. Then, multiply this removal amount by the total mass of the scrap steel to be added to obtain the total amount of sulfur element to be removed. Subsequently, according to the chemical reaction equation between calcium carbide and sulfur, determine its theoretical mass ratio as 1.125, that is, removing 1 kg of sulfur theoretically requires 1.125 kg of pure calcium carbide. Calculate the product of the total amount of sulfur element and the theoretical mass ratio to obtain the theoretical demand for calcium carbide. Then, set a preset purification efficiency coefficient, which generally ranges from 70% to 90%, and is set to 80% in this embodiment of the invention. Divide the theoretical demand by the purification efficiency coefficient to calculate the actual demand for calcium carbide. Finally, multiply the actual demand by a safety factor, which generally ranges from 1.1 to 1.3, and is set to 1.2 in this embodiment of the invention, to finally obtain the preset addition amount of calcium carbide.

[0091] This invention provides a specific embodiment, taking the production of HT250 grade gray cast iron parts as an example. The target carbon content is 4.1%; the target silicon content is 2.0%; the mass of molten iron in the smelting furnace is 1000kg; the total mass of scrap steel to be added is 200kg; sampling inspection: 5 samples were randomly selected for testing, and the maximum carbon content was 2.8%, the minimum was 2.6%; the average sulfur content was 0.18%; the average phosphorus content was 0.14%, so the carbon content range is 2.8% - 2.6% = 0.2%; the preset carbon content range is preferably 0.15%; since 0.2% > 0.15%, it is determined that the composition of this batch of scrap steel is uneven and does not meet the requirements for addition, so the scrap steel to be added needs to be matched with purified materials; the calculation of the purified materials takes desulfurization as an example, the preset sulfur content is 0.08%, the sulfur content of the scrap steel is 0.18% which exceeds the preset content, so purified materials need to be added; the sulfur content in the scrap steel needs to be reduced by: 0.18% - 0.08% = 0.10% means that 0.10 kg of sulfur needs to be removed from every 100 kg of scrap steel. For a total mass of 200 kg of scrap steel, the total mass of sulfur to be removed is (0.10 / 100)*200 kg = 0.20 kg of sulfur. According to the chemical reaction equation of calcium carbide (CaC2) and sulfur (S), the theoretical mass ratio is 1.125. Therefore, the theoretical amount of CaC2 required is: 0.20 kg S*1.125 = 0.225 kg. Considering that the actual reaction is incomplete, a preset purification efficiency coefficient of 80% is introduced. Then the actual amount of CaC2 required is: 0.225 kg / 0.8 = 0.281 kg. To ensure the effect, a safety factor of 1.2 is introduced. Finally, the preset amount of calcium carbide to be added for this batch of 200 kg of scrap steel is: 0.281 kg*1.2 = 0.34 kg.

[0092] Specifically, this invention objectively determines the batch uniformity of scrap steel by detecting the carbon content range, and calculates the preset addition amount of purification material based on the sulfur and phosphorus content. This ensures that when carbon reduction control is performed in subsequent steps, the purification agent can be added synchronously according to the calculated amount of purification material required per unit mass of scrap steel, thereby actively neutralizing the impurities introduced by the scrap steel. This achieves a synergy between carbon reduction and purity maintenance, laying a purity foundation for the production of high-quality castings.

[0093] Please see Figure 4 As shown, it is a logic block diagram of an embodiment of the present invention for determining whether eutectic undercooling occurs based on the instantaneous slope.

[0094] Specifically, in step S2, after sampling the molten iron in the furnace, the silicon and phosphorus content in the molten iron is detected using a spectrometer. Based on the silicon content in the sampled molten iron falling within a preset thermal analysis silicon content range, thermal analysis is performed on the sampled molten iron to obtain its cooling curve. The instantaneous slope of the cooling curve during the eutectic reaction is calculated. The absolute value of the instantaneous slope is compared with the absolute value of the preset instantaneous slope to determine whether eutectic supercooling has occurred. Based on the judgment result, the carbon equivalent and actual carbon content of the sampled molten iron are calculated using a corresponding calculation strategy.

[0095] If the absolute value of the instantaneous slope is less than or equal to the preset absolute value of the instantaneous slope, it is determined that the eutectic plateau is gentle and no eutectic undercooling has occurred, and the first calculation strategy is adopted.

[0096] If the absolute value of the instantaneous slope is greater than the absolute value of the preset instantaneous slope, then the eutectic plateau is determined to be steep, and eutectic undercooling occurs, and the second calculation strategy is adopted.

[0097] In this embodiment of the invention, the preset thermal analysis silicon content range is 1.9% to 2.1%, and the preferred range is 1.95% to 2.05%. The preferred range can be determined according to the actual situation and is not specifically limited here.

[0098] In this embodiment of the invention, the instantaneous slope is the rate of temperature change per unit time of the cooling curve within the eutectic temperature plateau range.

[0099] In this embodiment of the invention, the preset instantaneous slope ranges from 5℃ / s to 15℃ / s, and the preferred value is 10℃ / s. The preferred range and preferred value can be determined according to the actual situation, and are not specifically limited here.

[0100] In this embodiment of the invention, the first calculation strategy first calculates the carbon equivalent of the sampled molten iron based on the primary crystallization temperature and the eutectic temperature using a preset first regression equation. The calculation process is as follows: multiply the primary crystallization temperature by a first temperature coefficient, multiply the eutectic temperature by a second temperature coefficient, and then add the two products to a constant term to obtain the carbon equivalent. Subsequently, based on the carbon equivalent calculated above, and combined with the silicon and phosphorus content detected by the spectrometer, the actual carbon content of the molten iron is calculated. The calculation follows the definition formula of the carbon equivalent and undergoes transformation. The process is as follows: subtract the product of the silicon content and one-third from the carbon equivalent, and then subtract the product of the phosphorus content and one-third to obtain the actual carbon content.

[0101] In this embodiment of the invention, the second calculation strategy first calculates the difference between the measured eutectic temperature and the theoretical eutectic temperature to obtain the undercooling. The theoretical eutectic temperature can be pre-calculated based on the target composition or measured composition of the molten iron using existing thermodynamic databases or empirical formulas. Then, the undercooling is multiplied by a correction factor to obtain a temperature compensation value; the correction factor is a constant between 0.5 and 0.9, preferably 0.7 in this invention. Finally, the temperature compensation value is added to the measured eutectic temperature to obtain the corrected eutectic temperature. After obtaining the corrected eutectic temperature, the method in the first calculation strategy is used, i.e., the carbon equivalent is calculated using the first regression equation, and then the final actual carbon content is calculated by combining the silicon and phosphorus contents.

[0102] In this embodiment of the invention, the first temperature coefficient, the second temperature coefficient, and the constant term are determined based on a large number of representative molten iron samples through experimental measurement and mathematical statistical methods. The specific determination process is as follows: multiple sets of molten iron samples covering the target production range are prepared, and their primary crystallization temperature, eutectic temperature, and true carbon equivalent are measured simultaneously and accurately. Subsequently, regression algorithms such as the least squares method are used to fit the specific values ​​of the first temperature coefficient, the second temperature coefficient, and the constant term that minimize the overall error between the predicted carbon equivalent and the true carbon equivalent. The first temperature coefficient is preferably 0.5, the second temperature coefficient is preferably 0.1, and the constant term is preferably -50.5.

[0103] The present invention provides a specific embodiment, taking the production of HT250 grade gray cast iron parts as an example, taking a sample of molten iron from the smelting furnace and detecting it using a spectrometer. The measured silicon content was 2.02% and the phosphorus content was 0.08%. Since the silicon content of 2.02% falls within the preset thermal analysis silicon content range, thermal analysis is permitted. The molten iron sample was poured into the thermal analysis sample cup, and the instrument automatically recorded the cooling curve. The instantaneous slope of the cooling curve during the eutectic reaction stage, i.e., the temperature change rate, was calculated to be 8.0℃ / s, which meets the requirement of being less than or equal to the preset absolute value of the instantaneous slope. Therefore, it was determined that no eutectic supercooling occurred, and the first calculation strategy was used to calculate the actual carbon content. The primary crystallization temperature TL was identified as 1165℃ and the eutectic temperature TE as 1148℃ from the cooling curve. Using a preset first regression equation, for example, in the form CE = A×TL + B×TE + C, where the coefficients A, B, and C were determined through historical data fitting to be 0.05, 0.10, and -50.5, respectively, and CE is the carbon equivalent, the calculation result is 0.05×1165 + 0.10×1148-50.5 = The carbon equivalent was obtained from 4.35%. Then, the actual carbon content was calculated using the carbon equivalent definition formula (CE = C + (Si + P) / 3) as C = CE - (Si + P) / 3. Substituting the silicon content of 2.02% and phosphorus content of 0.08% measured by a spectrometer, along with the calculated carbon equivalent of 4.35%, the actual carbon content was found to be 4.35% - (2.02% + 0.08%) / 3 = 4.35% - 0.70% = 3.65%.

[0104] Specifically, this invention intelligently diagnoses eutectic overcooling by calculating the instantaneous slope of the cooling curve during the eutectic reaction and accordingly activates different calculation strategies: the first calculation strategy is used when there is no overcooling, and the second calculation strategy is activated when there is overcooling. This effectively avoids misjudgment of carbon content caused by distortion of the cooling curve and provides a solid and reliable data foundation for all subsequent control decisions.

[0105] Please see Figure 5 As shown, it is a logic block diagram of the present invention for controlling the smelting process of gray cast iron in the smelting furnace according to the actual carbon content.

[0106] Specifically, after calculating the actual carbon content of the sampled molten iron, the smelting process of gray cast iron in the smelting furnace is controlled based on the comparison between the actual carbon content and the target carbon content.

[0107] If the actual carbon content is less than the target carbon content, it is determined that the actual carbon content of the sampled molten iron is insufficient. In this case, it is determined that a carbon raiser should be added to the smelting furnace to regulate the carbon content of the molten iron.

[0108] If the actual carbon content is greater than the target carbon content, it is determined that the actual carbon content in the sampled molten iron is excessive. At this time, it is determined to add scrap steel and purification materials supporting the scrap steel into the smelting furnace to regulate the carbon content in the molten iron.

[0109] In the embodiment of the present invention, the value range of the target carbon content is 4.0% - 4.2%. The preferred value of the present invention is 4.1%. The preferred value range and the preferred value of the target carbon content can be determined according to the actual situation and are not specifically limited herein.

[0110] In the embodiment of the present invention, the addition amount of the carbon increasing agent is first obtained by calculating the product of the mass of the molten iron in the smelting furnace and the absolute difference between the target carbon content and the actual carbon content to obtain the total mass of pure carbon that needs to be supplemented into the molten iron. Subsequently, the product of the carbon content of the carbon increasing agent and the preset absorption rate of the carbon increasing agent is calculated. Finally, the ratio of the pure carbon mass to the product is calculated to obtain the addition amount of the carbon increasing agent.

[0111] Among them, the carbon content of the carbon increasing agent is the percentage of carbon element in the carbon increasing agent added into the smelting furnace and is obtained according to the specific carbon increasing agent product used.

[0112] The preset absorption rate of the carbon increasing agent is the proportion of the added carbon increasing agent absorbed by the molten iron and is an empirical value obtained based on long-term production data statistics. Its value range is 80% - 95%. The preferred value of the present invention is 90%. The preferred value range and the preferred value can be determined in advance according to the on-site process and are not specifically limited herein.

[0113] In the embodiment of the present invention, the addition amount of the scrap steel is first obtained by calculating the product of the mass of the molten iron in the smelting furnace and the difference between the actual carbon content and the target carbon content to obtain the mass of the excessive carbon that needs to be diluted. Subsequently, the difference between the target carbon content and the preset carbon content of the scrap steel is calculated. Finally, the ratio of the mass of the excessive carbon to the difference is calculated to obtain the addition amount of the scrap steel.

[0114] Among them, the preset carbon content of the scrap steel is an empirical parameter preset based on historical data for initial calculation rather than the measured carbon content of the scrap steel. Its value range is 0.2% - 0.4%. The preferred value is 0.3%. The preferred value range and the preferred value can be determined in advance according to the on-site process and are not specifically limited herein.

[0115] Specifically, the addition amount of the purification material is first obtained by calculating the product of the addition amount of the scrap steel and the addition amount of the purification material required per unit mass of the scrap steel. Among them, the addition amount of the purification material required per unit mass of the scrap steel is the ratio of the preset addition amount in the step S1 to the total mass of the scrap steel to be added.

[0116] This invention provides a specific embodiment, taking the production of HT250 grade gray cast iron parts as an example. In step S2, the actual carbon content is 3.65%, which is less than the target carbon content. Therefore, a control strategy of adding a carbon raiser is implemented. First, the carbon deficit is calculated, that is, the total mass of pure carbon to be added to the molten iron, which is the mass of molten iron multiplied by the carbon content difference, i.e., 1000 kg (4.10% - 3.65%) = 1000 kg × 0.0045 = 4.5 kg of carbon. A carbon raiser with a carbon content of 98% is selected, and the calculation is performed using a preset carbon raiser absorption rate of 90%. Considering the absorption rate, the theoretical effective carbon content of the required carbon raiser is: 98% × 90% = 88.2%; therefore, the required carbon raiser mass is 4.5 kg / (98% × 90%) = 4.5 kg / 0.882 = 5.10 kg.

[0117] Specifically, in step S4, a second sample is taken from the molten iron in the smelting furnace to obtain the actual carbon content of the molten iron after adjustment and the residual amount of the key impurity elements. Based on the comparison between the absolute deviation of the actual carbon content after adjustment and the target carbon content and the preset absolute deviation value, it is determined whether the adjustment of the gray cast iron in the smelting furnace is qualified. Under unqualified conditions, the actual absorption rate of the single-time carbonizer and the actual effective carbon content of the scrap steel are calculated.

[0118] If the absolute deviation value is less than or equal to the preset absolute deviation value, then the control of the gray cast iron in the smelting furnace is deemed to be qualified.

[0119] If the absolute deviation value is greater than the preset absolute deviation value, it is determined that the control of the gray cast iron in the smelting furnace is unqualified. At this time, the actual absorption rate of the carbon raiser and the actual effective carbon content of the scrap steel are calculated.

[0120] In this embodiment of the invention, the preset absolute deviation value is the allowable tolerance of the current gray cast iron, and the value range is 0.04% to 0.06%. The preferred value of the preset carbon content absolute deviation value can be determined according to the actual situation, and is not specifically limited here.

[0121] In this embodiment of the invention, the actual absorption rate of the carbon raiser is calculated under the condition that the control of the gray cast iron in the smelting furnace is unqualified. In practical applications, the actual carbon increment achieved by this control is obtained by first calculating the product of the difference between the mass of the molten iron in the smelting furnace and the actual carbon content after control and the actual carbon content before control. Then, the total amount of carbon added by this control is obtained by calculating the product of the amount of carbon raiser added and the carbon content of the carbon raiser. Finally, the ratio of the carbon increment to the total carbon content is calculated to obtain the actual absorption rate of the carbon raiser.

[0122] In this embodiment of the invention, the actual effective carbon content of the scrap steel is calculated under the condition that the control of the gray cast iron in the smelting furnace is unqualified. In practical applications, the product of the mass of the molten iron in the smelting furnace and the difference between the actual carbon content before and after control is first calculated to obtain the total mass of carbon elements diluted by the addition of scrap steel. Then, the total mass of diluted carbon elements is divided by the amount of scrap steel added in this control, and finally the actual effective carbon content of the scrap steel under the current smelting conditions is calculated.

[0123] Specifically, the purification effect is determined based on a comparison between the residual amount of the key impurity element and the preset residual amount.

[0124] If the residual amount is less than or equal to the preset residual amount, the purification effect is determined to be up to standard, and the purification process is completed.

[0125] If the residual amount is greater than the preset residual amount, the purification effect is determined to be substandard, and the actual purification efficiency of the purified material is calculated.

[0126] In this embodiment of the invention, the key impurity elements are sulfur and phosphorus. The preset residual amount of sulfur ranges from 0.05% to 0.10%, and the preferred value in this invention is 0.08%. The preset residual amount of phosphorus ranges from 0.06% to 0.12%, and the preferred value in this invention is 0.10%. The preferred range and preferred value can be determined according to the actual situation, and are not specifically limited here.

[0127] In this embodiment of the invention, the actual purification efficiency is obtained by first calculating the expected total impurity amount by the amount of scrap steel added and the average content of the corresponding impurity elements of the batch of scrap steel detected in step S1; then calculating the actual amount removed by the difference between the expected total mass of impurities and the residual amount of the impurity in the second sampled molten iron and the content of the impurity in the molten iron before adjustment; and finally calculating the ratio of the actual amount removed to the expected total impurity amount to obtain the actual purification efficiency.

[0128] Please see Figure 6 As shown, it is a logic block diagram of an embodiment of the present invention for optimizing the amount of carburizer added based on the actual absorption rate of the carburizer added to the molten iron.

[0129] Specifically, based on the condition that the carbon raiser does not meet the control requirements after addition, the amount of carbon raiser to be added is optimized according to the comparison between the actual absorption rate and the target absorption rate of the carbon raiser.

[0130] If the actual absorption rate of the carbonizer is less than the target carbonizer absorption rate, then the preset carbonizer absorption rate is reduced. The reduction is positively correlated with the deviation between the actual carbonizer absorption rate and the target carbonizer absorption rate, thereby increasing the amount of carbonizer added to ensure that the carbon content of the molten iron in the smelting furnace meets the standard.

[0131] If the actual absorption rate of the carbonizer is greater than the target carbonizer absorption rate, then the preset carbonizer absorption rate is increased. The increase is positively correlated with the deviation between the actual carbonizer absorption rate and the target carbonizer absorption rate, thereby reducing the amount of carbonizer added and ensuring that the carbon content of the molten iron in the smelting furnace meets the standard.

[0132] In this embodiment of the invention, the target carbon raiser absorption rate is an empirical value derived from long-term production data statistics. It represents the average absorption efficiency that the carbon raiser is expected to achieve under the current process conditions, and the value ranges from 85% to 95%. The preferred value in this invention is 90%. The preferred range and preferred value of the target carbon raiser can be determined according to the actual situation, and are not specifically limited here.

[0133] Please see Figure 7 As shown, it is a logic block diagram of an embodiment of the present invention for optimizing the amount of scrap steel to be added based on the actual effective carbon content of the scrap steel.

[0134] Specifically, based on the condition that the control is not up to standard after adding scrap steel, the amount of scrap steel to be added is optimized according to the comparison between the actual effective carbon content of the scrap steel and the target carbon content of the scrap steel.

[0135] If the actual effective carbon content of the scrap steel is less than the target carbon content of the scrap steel, then the carbon content of the preset scrap steel is reduced. The reduction is positively correlated with the deviation between the actual effective carbon content of the scrap steel and the target carbon content of the scrap steel, thereby reducing the amount of scrap steel added and preventing the carbon content from being too low due to excessive dilution, so that the carbon content of the molten iron in the smelting furnace meets the standard.

[0136] If the actual effective carbon content of the scrap steel is greater than the target carbon content of the scrap steel, then the carbon content of the preset scrap steel is increased. The increase is positively correlated with the deviation between the actual effective carbon content of the scrap steel and the target carbon content of the scrap steel, thereby increasing the amount of scrap steel added to prevent the carbon content from being too high due to insufficient dilution, so that the carbon content of the molten iron in the smelting furnace meets the standard.

[0137] In this embodiment of the invention, the target carbon content of scrap steel is an empirical value derived from long-term production data statistics. It represents the average carbon content that the system expects scrap steel to achieve under the current process conditions, and the value ranges from 0.2% to 0.4%. The preferred value in this invention is 0.3%. The preferred range and preferred value of the target carbon content of scrap steel can be determined according to the actual situation, and are not specifically limited here.

[0138] Please see Figure 8 As shown, it is a logic block diagram of an embodiment of the present invention for optimizing the amount of purification material to be added to the scrap steel based on the actual purification efficiency.

[0139] Specifically, under the condition that the purification does not meet the standards, the amount of purification material to be added for the scrap steel is optimized based on the comparison between the actual purification efficiency and the target purification efficiency.

[0140] If the actual purification efficiency is less than the target purification efficiency, the preset purification efficiency coefficient is adjusted downward. The adjustment range is positively correlated with the efficiency deviation between the actual purification efficiency and the target purification efficiency. That is, the larger the efficiency deviation, the greater the adjustment range of the preset purification efficiency coefficient, thereby increasing the amount of purification material added to ensure that the purification effect meets the standard.

[0141] If the actual purification efficiency is greater than the target purification efficiency, then the preset purification efficiency coefficient is increased. The increase is positively correlated with the efficiency deviation between the actual purification efficiency and the target purification efficiency. That is, the larger the efficiency deviation, the greater the increase in the preset purification efficiency coefficient, thereby reducing the amount of purification material added, ensuring that the re-purification effect meets the standard and saving costs.

[0142] In this embodiment of the invention, the target purification efficiency is the average efficiency that the purified material is expected to achieve under the current process conditions, which is based on long-term production data statistics. The value range is 75% to 90%, and the preferred value in this invention is 85%. The preferred value range and preferred value can be determined according to the actual situation, and are not specifically limited here.

[0143] Specifically, this invention uses secondary sampling data to back-calculate the actual absorption rate of the carbon-raising agent, the actual effective carbon content of scrap steel, and the actual purification efficiency of the purified material. These measured values ​​are then compared with the target values, and the corresponding model preset parameters are dynamically optimized according to the positive correlation of the deviation. This closed loop of "execution-verification-back-calculation-optimization" enables the system to adapt to fluctuations in raw materials and processes, and achieve continuous self-improvement.

[0144] Specifically, through the comprehensive application of the aforementioned technical means, this invention ensures the extreme stability of carbon content and purity in molten iron, providing reliable performance and microstructure guarantees for high-end machine tool castings. Simultaneously, the significant increase in first-pass yield, substantial reduction in rework and scrap, and precise calculation and waste avoidance of raw materials such as carbon raisers, scrap steel, and purified materials collectively bring significant economic benefits. This invention represents a data-driven, precisely controllable advanced production model and is a key practice for the foundry industry towards intelligent and green manufacturing.

[0145] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A method for controlling carbon content in thermal analysis of gray cast iron, characterized in that, include, Prepare the carbon raiser and the scrap steel to be added. Determine whether the scrap steel meets the conditions for addition by detecting the carbon content range in the scrap steel to be added. Calculate the amount of purification material to be added based on the content of key impurity elements. Samples of gray cast iron were taken from the smelting furnace. Based on the fact that the silicon content in the sampled iron was within the preset thermal analysis silicon content range, thermal analysis was performed on the sampled iron to obtain the instantaneous slope during the eutectic reaction, in order to determine whether eutectic supercooling occurred, and to determine the carbon equivalent and actual carbon content of the sampled iron. The process of determining whether eutectic undercooling has occurred and calculating the carbon equivalent and actual carbon content of the sampled molten iron using a corresponding calculation strategy includes... Obtain the primary crystallization temperature and eutectic temperature during the thermal analysis of the sampled iron; The instantaneous slope is obtained by acquiring the cooling curve of the sampled molten iron and calculating the rate of temperature change per unit time within the eutectic temperature plateau range. The absolute value of the instantaneous slope is compared with the absolute value of the preset instantaneous slope; Based on the fact that the absolute value of the instantaneous slope is less than or equal to the preset absolute value of the instantaneous slope, it is determined that no eutectic undercooling phenomenon has occurred. The carbon equivalent and the actual carbon content are calculated using the first regression equation. Based on the fact that the absolute value of the instantaneous slope is greater than the absolute value of the preset instantaneous slope, it is determined that a eutectic supercooling phenomenon has occurred. After compensating for the eutectic temperature, the first regression equation is used to calculate the carbon equivalent and the actual carbon content. Based on the actual carbon content, determine the addition of a carbon raiser, scrap steel, and purification materials that are compatible with the scrap steel to the molten gray cast iron in the smelting furnace; To obtain the actual carbon content and residual amount of key impurities after adding carbon raisers and scrap steel; When the control of the gray cast iron in the smelting furnace is deemed unqualified based on the determination result that the absolute deviation between the actual carbon content after adjustment and the target carbon content is greater than the preset absolute deviation value, the actual absorption rate of the single carbon additive and the actual effective carbon content of the scrap steel are obtained. When the residual amount is greater than the preset residual amount, it is determined that the purification effect is not up to standard, and the actual purification efficiency of the purified material is obtained. Under the condition of unqualified regulation, the amount of carbon refining agent and the amount of scrap steel added are adjusted according to the actual absorption rate of the carbon refining agent and the actual effective carbon content of the scrap steel. Under the condition that the purification does not meet the standards, the amount of purification material to be added for the scrap steel is adjusted according to the actual purification efficiency. Carbon control is achieved based on the optimized amounts of carbon raiser, scrap steel, and purified materials.

2. The method for controlling carbon content in thermal analysis of gray cast iron according to claim 1, characterized in that, The process of determining whether it is necessary to match the added scrap steel with purified materials based on the content of key impurity elements and calculating the required amount of purified materials to be added includes... Samples of the scrap steel to be added were taken; Obtain the content of key impurity elements in the sampled scrap steel; The content of the key impurity element is compared with the preset content; Based on the fact that the content of the key impurity element is greater than the preset content, it is determined that the scrap steel to be added needs to be matched with purified material and the preset addition amount of the purified material is calculated. The content of the key impurity elements is phosphorus and sulfur.

3. The method for controlling carbon content in thermal analysis of gray cast iron according to claim 2, characterized in that, The process of determining the addition of a carbon raiser, scrap steel, and purification materials to the molten gray cast iron in the smelting furnace based on the actual carbon content includes: Obtain the actual carbon content; The actual carbon content is compared with the target carbon content; Based on the fact that the actual carbon content is less than the target carbon content, it is determined that the actual carbon content in the sampled molten iron is insufficient, and a carbon raiser is added to the smelting furnace.

4. The method for controlling carbon content in thermal analysis of gray cast iron according to claim 3, characterized in that, The process of determining the addition of carbon raiser, scrap steel, and purification materials to the molten gray cast iron in the smelting furnace based on the actual carbon content also includes... Based on the fact that the actual carbon content is greater than the target carbon content, it is determined that the actual carbon content in the sampled molten iron is excessive. At this point, scrap steel and purification materials that are compatible with the scrap steel are added to the smelting furnace.

5. The method for controlling carbon content in thermal analysis of gray cast iron according to claim 4, characterized in that, The process of optimizing the amount of carbon recarrier added based on the actual absorption rate of the carbon recarrier includes the following steps: The actual absorption rate of the carbon additive is compared with the target absorption rate of the carbon additive; Since the actual absorption rate of the carbon additive is less than the target carbon additive absorption rate, it is determined to reduce the preset carbon additive absorption rate. The reduction is positively correlated with the deviation between the actual absorption rate and the target carbon additive absorption rate, so as to increase the amount of carbon additive added. Based on the fact that the actual absorption rate of the carbon additive is greater than the target absorption rate, the carbon additive absorption rate is increased by a predetermined amount. The increase is positively correlated with the deviation between the actual absorption rate and the target absorption rate, so as to reduce the amount of carbon additive added.

6. The method for controlling carbon content in thermal analysis of gray cast iron according to claim 5, characterized in that, The process of optimizing the amount of scrap steel added based on the actual effective carbon content of the scrap steel includes the following steps: The actual effective carbon content of the scrap steel is compared with the carbon content of the target scrap steel; Based on the fact that the actual effective carbon content of the scrap steel is less than the target carbon content of the scrap steel, the carbon content of the pre-set scrap steel is reduced. The reduction range is positively correlated with the deviation between the actual effective carbon content of the scrap steel and the target carbon content of the scrap steel, so as to reduce the amount of scrap steel added. The carbon content of the scrap steel is increased based on the fact that the actual effective carbon content of the scrap steel is greater than the target carbon content of the scrap steel. The increase is positively correlated with the deviation between the actual effective carbon content of the scrap steel and the target carbon content of the scrap steel, so as to increase the amount of scrap steel added.

7. The method for controlling carbon content in thermal analysis of gray cast iron according to claim 6, characterized in that, The process of optimizing the amount of purification material to be added for the scrap steel based on the actual purification efficiency includes the following steps: To obtain the residual amount of impurities in the molten iron from the second sampling and the impurity content in the molten iron before regulation; Obtain the expected total amount of impurities in the added scrap steel, and calculate the difference between the expected total amount of impurities and the residual amount and the impurity content to obtain the actual amount removed. The actual purification efficiency is obtained by calculating the ratio of the actual amount removed to the expected total amount of impurities. The actual purification efficiency is compared with the target purification efficiency; Based on the fact that the actual purification efficiency is less than the target purification efficiency, the preset purification efficiency coefficient is adjusted to be lowered. The adjustment range is positively correlated with the efficiency deviation between the actual purification efficiency and the target purification efficiency, so as to increase the amount of purification material added.

8. The method for controlling carbon content in thermal analysis of gray cast iron according to claim 7, characterized in that, The process of optimizing the amount of purification material to be added for the scrap steel based on the actual purification efficiency also includes... Based on the fact that the actual purification efficiency is greater than the target purification efficiency, the preset purification efficiency coefficient is increased. The increase is positively correlated with the efficiency deviation between the actual purification efficiency and the target purification efficiency, so as to reduce the amount of purification material added.

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