A dynamic assignment method of setting value for improving the service life of tundish slag line

Abstract

The present application relates to a kind of setting value dynamic assignment method for improving tundish slag line life, the method is through adjusting tundish weight set value in the process of tundish molten steel liquid level rise and fall change, and the tundish weight set value is as the dynamic assignment of next tundish weight set value, so that the molten steel liquid level height of tundish changes in the specified range, slag line forms uniform erosion zone in the up and down direction in tundish lining, to realize the purpose of improving tundish slag line life.The present application has the advantages that: tundish molten steel liquid level periodic rise / fall change, eliminate the step-shaped deep groove formed by slag line erosion on refractory surface, avoid the plug breakage accident or the accident of breaking tundish caused by stress;Using molten steel liquid level drop makes tundish covering agent form coating crust on refractory surface, when molten steel liquid level rises, the coating crust condensed on refractory surface slows down the erosion of refractory by isolating steel slag, improves refractory life.

Description

TECHNICAL FIELD

[0001] The present application relates to a set value dynamic assignment method for improving the service life of the slag line of a tundish. BACKGROUND

[0002] The role of the tundish in the continuous casting process is to store molten steel and realize continuous flow of large ladle casting. The metallurgical function of the tundish is to maintain a certain internal molten steel weight (bath depth) during pouring to realize sufficient floating of inclusions and purification of molten steel. Figure 2 The tundish weight automatic control system adjusts the molten steel flow entering the tundish by changing the opening degree of the large ladle slide plate to realize the control purpose of maintaining constant tundish weight, effectively reducing the labor intensity of workers, and ensuring product quality and production stability. Patent 202011110664.5, a tundish weight automatic control method, 201010281750.2, a continuous casting tundish molten steel level control device, 201310581013.8, a tundish constant liquid level control system, and 200710010670.1, a continuous casting tundish liquid level automatic stable precise control device, all aim to precisely control the tundish liquid level height to realize a method of fixing the slag line position. This method keeps the tundish weight constant and the slag line height unchanged, which leads to fixed erosion position of the tundish stopper and the tundish lining refractory, forming a clear slag line. With the extension of the tundish steel pouring time, the slag line depth will continuously increase, forming a stepped groove and stress, causing the stopper to break, the tundish lining to burn through, and the slag wall to burn and leak, directly affecting production safety and the service life of the tundish, and the refractory is not fully utilized (the available range of refractory > 200mm). When the tundish weight is constant for a long time, the continuous casting machine using the stopper flow control will cause the steel slag liquid level between the stopper and the tundish lining to solidify and form a welding rod problem, which causes the stopper to be unable to control the flow by rising and falling, and there is a production risk.

[0003] When the tundish weight is constant for a long time, the continuous casting machine using the stopper flow control will cause the steel slag liquid level between the stopper and the tundish lining to solidify and form a welding rod problem, which causes the stopper to be unable to control the flow by rising and falling, and there is a production risk. SUMMARY

[0004] To overcome the shortcomings of the prior art, the present application aims to provide a set value dynamic assignment method for improving the service life of the slag line of a tundish, which realizes periodic changes in the weight of the tundish, expands the fixed position slag line of the "set value constant" automatic control method of the tundish weight to a uniform erosion zone in the upward and downward directions, and causes the slag line and the tundish refractory to always have relative motion, thereby preventing the slag line from overlapping and the slag line from staying at one position for multiple times, which can cause excessive erosion of the refractory.

[0005] To achieve the above-mentioned purpose, the present application realizes the following technical solutions:

[0006] A set value dynamic assignment method for improving the service life of the slag line of a tundish, which includes two specific schemes, and specifically as follows:

[0007] Scheme one, the method is in the process of intermediate ladle liquid level rising and falling by adjusting the intermediate ladle weight set value, and the intermediate ladle weight set value as the next intermediate ladle weight set value of dynamic assignment, so that the intermediate ladle liquid level height in the specified range changes, the slag line in the intermediate ladle lining forms the uniform erosion zone in the up and down direction, to realize the purpose of improving the intermediate ladle slag line life; The intermediate ladle weight set value and dynamic assignment method are as follows:

[0008] 1) The calculation formula is: intermediate ladle weight set value = dynamic assignment ± intermediate ladle weight change; The initial dynamic assignment is the initial intermediate ladle weight at the moment of putting into work mode by the host computer, and the obtained intermediate ladle weight set value calculated is used as the dynamic assignment for the next intermediate ladle weight set value calculation;

[0009] The intermediate ladle weight set value calculated above requires to meet the condition: the set value is between the upper limit of the best intermediate ladle weight and the lower limit of the best intermediate ladle weight.

[0010] The change of intermediate ladle weight is the product of rising process speed or falling process speed and duration.

[0011] The specific steps are as follows:

[0012] a determination of initial dynamic assignment

[0013] The current intermediate ladle weight at the moment of putting into work mode by the host computer is the initial dynamic assignment, and the intermediate ladle weight set value calculated from the dynamic assignment is used as the next dynamic assignment; In this way, the intermediate ladle weight set value calculated each time is the dynamic assignment for the next intermediate ladle weight set value calculation;

[0014] b when the work mode is put into at the moment, the molten steel state is rising state; The calculation formula is as follows:

[0015] The set value of intermediate ladle weight = dynamic assignment + rising process speed * duration ①

[0016] In formula ①: the unit of dynamic assignment is t, the unit of rising process speed is t / min, the unit of duration is min, the unit of set value of intermediate ladle weight is t, and the duration is 10s-30s;

[0017] When the set value of intermediate ladle weight approaches the upper limit of the best intermediate ladle weight, the molten steel rising state is switched to falling state, and the calculation formula is as follows:

[0018] The set value of intermediate ladle weight = dynamic assignment - falling process speed * duration ②

[0019] In formula ②: the unit of falling process speed is t / min, and the duration is 10s-30s;

[0020] When the set value of the tundish weight approaches the lower limit of the optimal tundish weight, the molten steel is switched from the falling state to the rising state, and the calculation formula is formula ①.

[0021] The rising process speed and the falling process speed calculation formulae are as follows:

[0022] Rising process speed = (upper limit of optimal tundish weight - lower limit of optimal tundish weight) / τ ③

[0023] Falling process speed = rising process speed / n ④

[0024] Falling process speed ≤ rising process speed ⑤

[0025] In formulae ③-⑤, τ is the rising time, the unit is min, the range of τ is 2-4, n is the falling speed coefficient, the range of n is 1-3, the upper limit of the optimal tundish weight is t, and the lower limit of the optimal tundish weight is t;

[0026] The parameters inputted by the host computer manually are transmitted to the duration, the rising time τ, the falling speed coefficient n, the upper limit of the optimal tundish weight, and the lower limit of the optimal tundish weight.

[0027] Scheme two, the method adjusts the tundish weight set value within a certain time interval, and the set value is used as the dynamic assignment of the next tundish weight set value, so that the molten steel liquid level height of the tundish changes within the specified range, and the slag line forms a uniform erosion zone in the upward and downward directions on the tundish lining, so as to achieve the purpose of improving the service life of the tundish slag line; the tundish weight set value and the dynamic assignment method are as follows:

[0028] 1) The calculation formula is: tundish weight set value = dynamic assignment ± slag line interval weight; the initial dynamic assignment is the initial tundish weight at the moment of inputting the working mode by the host computer, and the tundish weight set value obtained by calculation is used as the dynamic assignment for the next tundish weight set value calculation;

[0029] The tundish weight set value calculated above requires to meet the condition that the set value is between the upper limit of the optimal tundish weight and the lower limit of the optimal tundish weight.

[0030] The specific steps are as follows:

[0031] a Determination of the initial "dynamic assignment"

[0032] The current tundish weight at the moment of inputting the working mode by the host computer is the initial dynamic assignment, and the tundish weight set value calculated from the dynamic assignment is used as the next dynamic assignment; in this way, the tundish weight set value obtained by calculation each time is the dynamic assignment for the next tundish weight set value calculation;

[0033] b When the working mode is put into the instant, the molten steel state is rising state; the calculation formula is as follows:

[0034] The set value of the tundish weight = dynamic assignment + slag line interval weight ⑥

[0035] In formula ⑥, the unit of dynamic assignment is t; the range of slag line interval weight is 0.2-0.6, the unit is t; the unit of the set value of the tundish weight is t;

[0036] When the set value of the tundish weight approaches the upper limit of the optimal tundish weight, the molten steel rising state is switched to the descending state, and the calculation formula is as follows:

[0037] The set value of the tundish weight = dynamic assignment - slag line interval weight ⑦

[0038] In formula ⑦, when the molten steel rising state is switched to the descending state, it is the reversing state, at this time, the dynamic assignment is calculated according to the following formula:

[0039] The dynamic assignment of the reversing state = the dynamic assignment before reversing + coincidence compensation weight ⑧

[0040] In formula ⑧, the slag line interval weight = the weight corresponding to the slag line width, the coincidence compensation weight < the slag line interval weight / 2, the unit of coincidence compensation weight is t;

[0041] When the set value of the tundish weight approaches the lower limit of the optimal tundish weight, the molten steel is switched from the descending state to the rising state, and the set value of the tundish weight is calculated according to formula ⑥; the dynamic assignment of the reversing state is formula ⑧.

[0042] The dynamic assignment change range of the set value of the tundish weight meets the following conditions:

[0043] Upper limit range:

[0044] The upper limit weight of dynamic assignment ≤ the tundish overflow weight - overflow safety margin ⑨

[0045] Lower limit range:

[0046] The lower limit weight of dynamic assignment ≥ the minimum weight of tundish metallurgical function + the weight of molten slag in tundish ⑩

[0047] In formula ⑨, the unit of upper limit weight is t, the unit of tundish overflow weight is t, and the unit of overflow safety margin is t; in formula ⑩, the unit of lower limit weight is t, the unit of the minimum weight of tundish metallurgical function is t, and the unit of the weight of molten slag in tundish is t.

[0048] The change trend of the intermediate ladle weight setting value is a continuous process, and one process cycle includes: rising-reversing-falling-reversing-rising. When the manual control of the large tank slide is started during the process, the dynamic assignment mode of the intermediate ladle weight setting value is paused, the data is kept, and when the automatic control mode is started again, the starting point is the interruption in the last cycle.

[0049] The upper limit of the optimal weight of the intermediate weight is the nominal capacity of the intermediate ladle multiplied by 0.9, and the lower limit of the optimal weight of the intermediate weight is the nominal capacity of the intermediate ladle multiplied by 0.7.

[0050] Compared with the prior art, the beneficial effects of the present application are:

[0051] 1. By continuously adjusting the setting value of the intermediate ladle weight, the molten steel level of the intermediate ladle is periodically raised / lowered at a set speed;

[0052] 2. The periodic raising / lowering of the molten steel level of the intermediate ladle eliminates the stepped deep grooves formed by the erosion of the slag line on the refractory surface, and avoids the breakage of the stopper or the breakout accident caused by stress;

[0053] 3. The slag line (width < 20 mm) of the constant weight control method is expanded to a uniform erosion band (width > 200 mm) in the upward and downward directions;

[0054] 4. The molten steel level is lowered to form a coating crust on the refractory surface of the covering agent in the intermediate ladle, and when the molten steel level rises, the coating crust condensed on the refractory surface slows down the erosion of the refractory by the molten steel slag, thereby improving the service life of the refractory;

[0055] 5. During the lowering of the molten steel level in the intermediate ladle, the sintered intermediate ladle dry material powder after melting is sintered on the surface of the intermediate ladle lining, the stopper slag line and the long nozzle, forming a hot melting repair layer which offsets the erosion of the molten steel when the molten steel level in the intermediate ladle rises;

[0056] 6. The molten steel level in the intermediate ladle is continuously changed, and there is always relative motion between the slag line and the intermediate ladle refractory, thereby avoiding the generation of "slag crust" and eliminating the problem of welding rod;

[0057] 7. The fluctuation range of the intermediate ladle weight is limited to meet the quality of the cast slab and production safety. BRIEF DESCRIPTION OF DRAWINGS

[0058] Figure 1 Flowchart of the setting value dynamic assignment mode for improving the service life of the intermediate ladle slag line.

[0059] Figure 2 Flowchart of the setting value dynamic assignment mode for improving the service life of the intermediate ladle slag line.

[0060] Figure 3 Intermediate ladle weight change curve in the dynamic slag line anti-erosion mode state.

[0061] Figure 4 is the tundish weight change curve in the state of the slag line position interval uniform erosion prevention mode.

[0062] Figure 5 is the tundish weight change curve in the state of the slag line position interval uniform erosion prevention mode.

[0063] Figure 6 is the tundish weight change curve in the state of the slag line position interval uniform erosion prevention mode.

[0064] In the figure: 1-long nozzle 2-hanging slag layer 3-stopper 4-tundish lining 5-coating agent 6-slag line 7-tundish molten steel 8-large tank 9-rotary table 10-large tank molten steel. DETAILED DESCRIPTION

[0065] The application will be described in detail below with reference to the accompanying drawings of the specification, but it should be pointed out that the implementation of the application is not limited to the following embodiments.

[0066] The existing tundish weight "set value constant" automatic control mode in the workshop is to change the large tank slide plate opening degree, adjust the molten steel flow entering the tundish, realize the constant tundish liquid level height, make the tundish weight constant, and keep the height of the slag line unchanged; this control mode will make the slag line stay at one position for many times, resulting in excessive erosion of refractory materials. On the basis of the tundish weight "set value constant" automatic control mode, the set value dynamic assignment method is added, the tundish molten steel liquid level height is periodically raised and lowered by continuously adjusting the tundish weight set value, the uniform distribution of the slag line in the tundish lining is realized by using the tundish refractory width, and the uniform erosion zone of the slag line in the up and down direction is formed.

[0067] The middle contains an overflow port for preventing overflow of the tundish molten steel 7 after the tundish is filled, and the molten steel will flow out from the overflow port into the accident tank due to the overflow port being lower than the edge of the tundish wall, and the tundish overflow weight is the maximum weight of the tundish full of molten steel; in production, the tundish cannot be completely filled, and a reserved distance is kept between the molten steel liquid surface and the overflow port, and the overflow safety margin range is 2-10t, and the larger the tundish, the larger the overflow safety margin.

[0068] The molten slag in the tundish is all non-metallic molten materials except molten steel, including tundish lining falling objects, molten steel oxidation generated dross, tundish coating agent, ladle slag, and refractory repair materials. The weight of the molten slag in the tundish is less than 0.2-0.5t, and the larger the tundish, the greater the weight of the molten slag in the tundish. When the weight of the molten slag in the tundish exceeds the standard, it will affect the quality of the cast slab, and the tundish needs to be replaced; for example, the tundish weight of 32t in the initial pouring range is only 0.12t-0.15t, which increases with the extension of the tundish use time, until it is greater than 0.2t, and the operator replaces the tundish.

[0069] The surface of the tundish lining 4 and stopper 3 is attached with molten repair slag, which includes refractory repair material added into the tundish and tundish covering agent 5. The refractory repair material is dry powder of the tundish working lining, and is added into the tundish. The refractory repair material is mixed with the tundish covering agent 5 to form hot molten repair slag, which is attached to the surface of the tundish lining 4, stopper 3 and long nozzle 1. When the liquid level of the molten steel 7 drops, the low-melting-point component in the attached layer will flow away, leaving the high-melting-point component to form a high-temperature slag hanging protective layer. The tundish covering agent 5 is used to prevent oxidation of the molten steel and to form the attached layer. The refractory repair material is dry powder of the tundish working lining, and the repair layer has the same properties as the tundish working lining. The tundish weight is controlled to drop at a fixed speed through a dynamic assignment process, and the refractory repair material is sintered on the surface of the tundish lining 4, stopper 3 and long nozzle 1 to form a certain thickness of the slag hanging protective layer, which repairs the erosion of the refractory. The refractory repair material adding position includes: around the stopper 3 and around the long nozzle 1; the refractory repair material is added less than or equal to 0.02t each time, and the total amount added in a tundish casting period is less than or equal to 0.2t; the interval of adding the refractory repair material is greater than 2 hours; the refractory repair material is added in the middle of the large ladle molten steel 10 casting; the use of the refractory repair material is required to be synchronized with the dynamic assignment of the set value of the tundish weight, and the thickness of the slag in the tundish is less than 100mm.

[0070] The set value dynamic assignment method and the tundish weight "set value constant" automatic control mode are started at the same time, and the set value dynamic assignment method includes two modes: dynamic slag line anti-erosion mode and uniform interval anti-erosion mode of slag line position. When the rising time τ and the falling speed coefficient n are determined, the operator selects the dynamic slag line anti-erosion mode, and when the rising process speed = the falling process speed = 0, the operator selects the uniform interval anti-erosion mode of slag line position. Two modes are selected. If an emergency occurs in production, the operator releases the set value dynamic assignment mode of the tundish weight through the upper computer: sets the parameters rising time τ, falling speed coefficient n, rising process speed and falling process speed to 0.

[0071] I. The set value dynamic assignment method of the dynamic slag line anti-erosion mode is as follows,

[0072] The tundish weight set value is adjusted during the rising and falling change of the tundish molten steel level, and the tundish weight set value is used as the dynamic assignment of the next tundish weight set value, so that the tundish molten steel level height changes within the specified range, and the slag line forms a uniform erosion zone in the upward and downward directions on the tundish lining, so as to achieve the purpose of improving the service life of the tundish slag line. The tundish weight set value and the dynamic assignment method are as follows:

[0073] 1) The calculation formula is: the intermediate ladle weight setting value = dynamic assignment ± the intermediate ladle weight change amount; the initial dynamic assignment is the initial intermediate ladle weight at the moment when the host computer is put into the working mode, and the intermediate ladle weight setting value obtained by calculation is taken as the dynamic assignment for the next intermediate ladle weight setting value calculation.

[0074] The intermediate ladle weight setting value calculated above is required to meet the condition that the setting value is between the upper limit of the intermediate ladle weight optimal weight and the lower limit of the intermediate ladle weight optimal weight, wherein the upper limit of the intermediate ladle weight optimal weight = the intermediate ladle nominal capacity * 0.9, and the lower limit of the intermediate ladle weight optimal weight = the intermediate ladle nominal capacity * 0.7.

[0075] The intermediate ladle weight change amount is the product of the duration and the rising or falling process speed as the intermediate ladle weight change amount.

[0076] The specific steps are as follows:

[0077] a. Determination of the initial dynamic assignment

[0078] The current intermediate ladle weight at the moment when the host computer is put into the working mode is taken as the initial dynamic assignment, and the intermediate ladle weight setting value calculated from the dynamic assignment is taken as the dynamic assignment for the next time; in this way, the intermediate ladle weight setting value obtained by calculation each time is taken as the dynamic assignment for the next intermediate ladle weight setting value calculation.

[0079] b. When the working mode is put into the moment, the molten steel state is in the rising state; the calculation formula is as follows:

[0080] The intermediate ladle weight setting value = dynamic assignment + rising process speed * duration ①

[0081] In formula ①, the unit of the dynamic assignment is t, the unit of the rising process speed is t / min, the unit of the duration is min, the unit of the intermediate ladle weight setting value is t, and the duration is 10s-30s;

[0082] When the intermediate ladle weight setting value approaches the upper limit of the intermediate ladle weight optimal weight, the molten steel rising state is switched to the falling state, and the calculation formula is as follows:

[0083] The intermediate ladle weight setting value = dynamic assignment - falling process speed * duration ②

[0084] In formula ②, the unit of the falling process speed is t / min, and the duration is 10s-30s;

[0085] When the intermediate ladle weight setting value approaches the lower limit of the intermediate ladle weight optimal weight, the molten steel is switched from the falling state to the rising state, and the calculation formula is formula ①.

[0086] The calculation formula of the rising process speed and the falling process speed is as follows:

[0087] Rising process speed = (upper limit of t - lower limit of t) / τ ③

[0088] Falling process speed = rising process speed / n ④

[0089] Falling process speed ≤ rising process speed ⑤

[0090] In formula ③-⑤, τ is the rising time, the unit is min, the range of τ is 2-4, n is the falling speed coefficient, the range of n is 1-3, the upper limit of t is t, and the lower limit of t is t;

[0091] The parameters inputted manually by the host computer are transmitted to the duration, the rising time τ, the falling speed coefficient n, the upper limit of t, and the lower limit of t.

[0092] The change trend of the t set value is a periodic continuous process, one process period includes: rising-reversing-falling-reversing-rising, when the large tank slide is started manually in the periodic process, the dynamic assignment mode of the t set value is paused, the data is kept, and when the automatic control mode is inputted again, the starting point is the interruption in the last period.

[0093] The dynamic assignment change range of the t set value meets the following conditions:

[0094] Upper limit range:

[0095] Dynamic assignment upper limit weight ≤ t overflow weight - t overflow safety margin ⑨

[0096] Lower limit range:

[0097] Dynamic assignment lower limit weight ≥ minimum weight of t metallurgical function + t molten slag weight in t ⑩

[0098] In formula ⑨, the upper limit weight unit is t, the t overflow weight unit is t, and the t overflow safety margin unit is t; in formula ⑩, the lower limit weight unit is t, the minimum weight of t metallurgical function unit is t, and the t molten slag weight in t unit is t.

[0099] II. The dynamic assignment method of the set value of the uniform erosion mode of the slag line position interval is as follows,

[0100] By adjusting the t set value within a certain time interval, and taking the set value as the dynamic assignment of the next t set value, the molten steel liquid level height of the t changes within the specified range, the slag line forms a uniform erosion zone in the up-down direction on the t inner lining, so as to achieve the purpose of improving the service life of the t slag line; the t set value and the dynamic assignment method are as follows:

[0101] 1) The calculation formula is: intermediate ladle weight set value = dynamic assignment ± slag line interval weight; the initial dynamic assignment is the initial intermediate ladle weight at the moment when the host computer is put into the working mode, and the obtained intermediate ladle weight set value is taken as the dynamic assignment for the next intermediate ladle weight set value calculation;

[0102] The intermediate ladle weight set value calculated above shall meet the condition that the set value is between the upper limit of the optimal intermediate ladle weight and the lower limit of the optimal intermediate ladle weight, wherein the upper limit of the optimal intermediate ladle weight = the nominal capacity of the intermediate ladle × 0.9, and the lower limit of the optimal intermediate ladle weight = the nominal capacity of the intermediate ladle × 0.7.

[0103] The specific steps are as follows:

[0104] a. Determination of the initial "dynamic assignment"

[0105] The current intermediate ladle weight at the moment when the host computer is put into the working mode is taken as the initial dynamic assignment, and the intermediate ladle weight set value calculated from the dynamic assignment is taken as the dynamic assignment for the next time; in this way, the intermediate ladle weight set value obtained each time is taken as the dynamic assignment for the next intermediate ladle weight set value calculation;

[0106] b. When the working mode is put into the rising state at the moment, the calculation formula is as follows:

[0107] The intermediate ladle weight set value = dynamic assignment + slag line interval weight

[0108] In formula ⑥, the unit of the dynamic assignment is t; the range of the slag line interval weight is 0.2-0.6, and the unit is t; the unit of the intermediate ladle weight set value is t;

[0109] When the intermediate ladle weight set value approaches the upper limit of the optimal intermediate ladle weight, the rising state of the molten steel is switched to the descending state, and the calculation formula is as follows:

[0110] The intermediate ladle weight set value = dynamic assignment - slag line interval weight

[0111] In formula ⑦, the unit of the dynamic assignment is t; the range of the slag line interval weight is 0.2-0.6, and the unit is t; the unit of the intermediate ladle weight set value is t; when the rising state of the molten steel is switched to the descending state, it is the reversing state, and the dynamic assignment is calculated according to the following formula:

[0112] The dynamic assignment in the reversing state = the dynamic assignment before the reversing + coincidence compensation weight

[0113] In formula ⑧, the slag line interval weight = the weight corresponding to the slag line width, the coincidence compensation weight < the slag line interval weight / 2, and the unit of the coincidence compensation weight is t;

[0114] When the set value of the tundish weight approaches the lower limit of the optimal tundish weight, the molten steel is switched from the falling state to the rising state, and the set value of the tundish weight is calculated by formula ⑥; the dynamic assignment of the switching state is formula ⑧.

[0115] The change trend of the tundish weight set value is a periodic continuous process, and one process cycle includes: rising-switching-falling-switching-rising. When the manual control of the large tank slide is started during the periodic process, the dynamic assignment of the tundish weight set value is suspended, and the data is kept. When the automatic control mode is put into operation again, the starting point is the interruption in the last cycle.

[0116] The dynamic assignment change range of the tundish weight set value meets the following conditions:

[0117] Upper limit range:

[0118] Dynamic assignment upper limit weight ≤ tundish overflow weight - overflow safety margin ⑨

[0119] Lower limit range:

[0120] Dynamic assignment lower limit weight ≥ minimum weight of tundish metallurgical function + weight of molten slag in tundish ⑩

[0121] In formula ⑨, the upper limit weight is in t, the tundish overflow weight is in t, and the overflow safety margin is in t; in formula ⑩, the lower limit weight is in t, the minimum weight of the tundish metallurgical function is in t, and the weight of the molten slag in the tundish is in t.

[0122] [Example 1]

[0123] See Figure 1 , see Figure 2A continuous casting machine, the tundish nominal capacity = 32t; the tundish weight optimal weight upper limit = the tundish nominal capacity × 0.9 = 32t × 0.9 = 28.8t, the tundish weight optimal weight upper limit h2 is 28; according to the tundish weight optimal weight lower limit = the tundish nominal capacity × 0.7 = 32t × 0.7 = 22.4t, because there will be slag in the tundish, the tundish weight optimal weight lower limit h3 = 24; the dynamic anti-erosion mode rising time τ = 4; the dynamic slag line anti-erosion mode falling speed coefficient n = 2.5; the duration = 1 / 2; the slag line interval uniform anti-erosion mode slag line interval weight = 0.6; the overlap compensation weight = 0.1; the start of the heat (the first furnace) = 1; after the start of the casting machine, the operator controls the tundish weight "set value constant" automatic control mode to start, at this time, the automatic control set value of the slide plate is a constant value, which is the initial "dynamic assignment", the initial "dynamic assignment" is transmitted to the dynamic assignment. For example: the tundish weight when the operator puts into the automatic mode is = 24.1, which satisfies h2 > the actual tundish weight > h3, the dynamic assignment mode of the set value of the tundish slag line life is started at the same time, when τ and n are determined, the operator can select the dynamic slag line anti-erosion mode, when the rising process speed = the falling process speed = 0, the operator can select the slag line position interval uniform anti-erosion mode, and the two modes are selected.

[0124] See Figure 1 , see Figure 2 , see Figure 3 , the operator selects the dynamic slag line anti-erosion mode, and the tundish weight is controlled according to the fixed speed through the dynamic assignment process, so as to guarantee that the hanging slag layer 2 forms sufficient thickness, the falling process speed ≤ the rising process speed, and the falling process speed ≤ the casting speed of the casting machine - the minimum safe flow of the ladle 8 slide plate, so that the opening of the ladle 8 slide plate > the minimum safe flow of the ladle 8 slide plate, and the freezing flow of the ladle 8 slide plate is avoided; the tundish weight is controlled according to the fixed speed through the dynamic assignment process, so that the erosion depth of the slag line and the hanging slag layer 2 within the action time is not greater than the thickness of the hanging slag protection layer, that is, the lining 4 of the tundish is not eroded; the formula is as follows:

[0125] The rising process speed = (h2 - h3) / τ = (28 - 24) / 4 = 1;

[0126] The falling process speed = the rising process speed / n = 1 / 2.5 = 0.4;

[0127] The trend state includes trend rise and trend fall, when the dynamic slag line anti-erosion mode is put into, the trend state is trend rise, the trend maintains continuity and is not affected by the replacement of the ladle (after the end of the ladle steel pouring, the rotating table rotates to complete the replacement of the ladle), and after the replacement of the tundish, the trend state is reset and the trend rise state is restored.

[0128] The current intermediate pack weight is the initial "dynamic assignment" value transmitted to the dynamic assignment point. The dynamic assignment value is 24.1. The next setpoint is calculated as: Next setpoint = Dynamic assignment value + Ascent speed * Duration =

[0129] 24.1 + 1 * 0.5 = 24.6.

[0130] Once the trend is determined (h2 > actual weight of intermediate package > h3), the next "set value" is converted to "dynamic assignment" and is ready to be written. When the "duration" of the dynamic assignment is reached, the "dynamic assignment = 24.6" is written into the "constant set value" automatic control mode for the intermediate package weight, and the next calculation is performed.

[0131] The next setpoint = dynamic assignment + ascent speed * duration = 24.6 + 1 * 0.5 = 25.1. A trend judgment is performed, and the next "setpoint" is converted to a "dynamic assignment," ready for writing. When the "duration" of the dynamic assignment is reached, the "dynamic assignment = 25.1t" is written into the automatic control mode of "constant setpoint" for the intermediate tundish weight, and the next calculation is performed.

[0132] The set values ​​24.1, 24.6, 25.1, 25.6, 26.1, 26.7, 27.2, and 27.7 are generated sequentially.

[0133] When the next setpoint = dynamic assignment + rising speed * duration = 27.7 + 1 * 0.5 = 28.2, a trend judgment is performed. The calculated next setpoint, and when this setpoint is greater than the optimal weight limit of 28t for the intermediate bale, the trend reversal is initiated, changing the trend from rising to falling. After the reversal, the next setpoint = dynamic assignment - falling speed * duration = 27.7 - 0.4 * 0.5 = 27.5. The next "setpoint" is converted into a "dynamic assignment" and is ready to be written. When the "duration" of the dynamic assignment is reached, the "dynamic assignment = 27.5t" is written into the basic program of the "constant setpoint" automatic control mode for the intermediate bale weight, and the next calculation is performed.

[0134] The set values ​​27.5, 27.3, 27.1, 26.9, 26.7, 26.5, 26.3, 26.1, 25.9, 25.7, 25.5, 25.3, 25.1, 24.9, 24.7, 24.5, 24.3, 24.1, and 23.9 are generated sequentially.

[0135] When the set value is 23.9, a trend judgment is performed. When the set value is less than the optimal lower limit of 24 for the weight of the intermediate package, the trend reversal is initiated, and the trend decline state is reversed to the trend rise state.

[0136] Example 2

[0137] See Figure 1 See Figure 2 See Figure 4 The operator selects the slag line position interval uniform anti-erosion mode, which is controlled by the ladle replacement, and the value is calculated once every time the ladle is replaced, to generate a set value of the tundish weight, and to perform a value writing dynamic assignment; the operator inputs parameters: slag line interval weight = 0.6; coincidence compensation weight = 0.1, default state, trend = rise, and the trend maintains continuity; wherein the slag line interval weight = the weight corresponding to the slag line width, the tundish nominal capacity = 32 t, the molten pool depth = 1200 mm, the static slag line width = 20 mm, the static slag line width corresponding to the molten steel weight = 32 ÷ 1200 × 20 = 0.53 t, the slag line corresponding weight is 0.53 t, and the slag line interval weight is taken as 0.6 t in consideration of safety, because the slag line cannot have any coincidence; for other continuous casting machines, only the static slag line width is measured, and the reasonable slag line interval weight can be known according to this method; every time the trend direction is changed, in order to prevent any two slag lines from coinciding, a small half of the slag line interval weight is added, that is, the coincidence weight compensation, and the specific value is less than or equal to half of the slag line interval weight, and the set value will always be offset by half of the slag line width.

[0138] The current tundish weight is the first "dynamic assignment = 24.1", the method synchronously calculates the next set value, and the next set value = dynamic assignment + slag line interval weight = 24.1 + 0.6 = 24.7.

[0139] The ladle 8 is replaced, the next set value is calculated, and the trend is judged, the judgment is completed, the calculated next "set value" is converted into "dynamic assignment", and is directly written; after the tundish weight "set value constant" automatic control mode is started, the writing "dynamic assignment" = 24.7 is directly executed and remains unchanged until the next ladle 8 is replaced.

[0140] When the ladle 8 is replaced again, the next set value = dynamic assignment + slag line interval weight = 24.7 + 0.6 = 25.3, the trend is judged, the judgment is completed, the calculated next "set value" is converted into "dynamic assignment", and is directly written; after the tundish weight "set value constant" automatic control mode is started, the writing "dynamic assignment = 25.3" is directly executed and remains unchanged until the next ladle 8 is replaced.

[0141] The set values 24.7, 25.3, 25.9, 26.5, 27.1, 27.7, and 28.3 are generated in turn;

[0142] When the next set value = 28.3, the trend is determined, the set value > the optimum weight upper limit of the tundish weight 28, the trend reverses, and the trend rising state reverses to the trend descending state; after the reversal, the dynamic assignment after the reversal of formula 7 = the dynamic assignment before the reversal + the overlap compensation weight, as the dynamic assignment, returns to recalculate the next set value = (the dynamic assignment + the overlap compensation weight) - the interval weight between the slag lines = (27.7 + 0.1) - 0.6 = 27.2; direct writing; when the tundish weight "set value constant" automatic control mode is started, the dynamic assignment = 27.2 written directly is executed and remains unchanged until the next ladle replacement.

[0143] The set values 27.2, 26.6, 26, 25.4, 24.8, 24.2, 23.6 are generated in sequence; when the set value = 23.6, the trend is determined, the set value < the optimum weight lower limit of the tundish weight 24 t, the trend reverses, and the trend descending state reverses to the trend rising state, and then the overlap compensation is performed; after the reversal, the dynamic assignment after the reversal of formula 7 = the dynamic assignment before the reversal + the sum of the overlap compensation weights, as the dynamic assignment, returns to recalculate the next set value = (the dynamic assignment + the overlap compensation weight) - the interval weight between the slag lines = (23.6 + 0.1) + 0.6 = 24.3; direct writing generates 24.3, 24.9, 25.5, 26.1, 26.7, 27.3 in sequence.

[0144] [Example 3]

[0145] See Figure 1 , see Figure 2 , see Figure 5 , pause and recovery in the dynamic slag line erosion prevention mode state:

[0146] In the "dynamic slag line erosion prevention mode" state, at the end of the ladle pouring (the tundish weight is less than 15 t), the operator switches the control mode of the slide plate to the manual control mode, see Figure 5 The automatic control mode enters the pause state at the position A where the ladle 8 slide plate is switched to the manual control, at this time, the parameters of the automatic control mode remain unchanged, the dynamic assignment = 26.1, and the trend descending state; the operator manually controls the slide plate to open to the maximum flow, and the tundish is filled to the brim, and then the slide plate is closed, and the rotating turntable 9 (used to transport the tundish full of molten steel to the steel pouring position) is rotated; due to the absence of the ladle molten steel 10 injection, the tundish weight rapidly decreases to 25.3, and after the ladle 8 is in place, the long nozzle 1 is installed; the operator manually controls the slide plate to open to the maximum flow, so that the tundish weight is in the increasing state, and the operator switches the manual control to the automatic control mode, and starts the tundish weight "set value constant" automatic control mode, but at this time, the actual tundish weight 25.3 ≠ the dynamic assignment 26.1, so the automatic control mode is delayed to start, see Figure 5The middle ladle 8 slide plate is converted to automatic control B, and the automatic control mode is started after a delay; the intermediate ladle weight "set value constant" automatic control mode is normally working, and the slide plate opening degree is adjusted to increase the intermediate ladle weight to the dynamic assignment value 26.1 and keep it, when the intermediate ladle actual weight = dynamic assignment value 26.1 and the duration > 0.5, the dynamic assignment function of the intermediate ladle weight set value dynamic assignment mode is restored, see Figure 5 The middle method pause state is released C, the dynamic set value update is restored, and the next set value is generated, the next set value = dynamic assignment - falling process speed * duration = 26.1 - 0.4 * 0.5 = 25.9; after trend judgment, the next set value is converted to "dynamic assignment" and is ready to be assigned. When the "duration" of the dynamic assignment reaches 0.5 min, a new "dynamic assignment = 25.9" is written in the basic program of the intermediate ladle weight "set value constant" automatic control mode, and the next calculation is performed.

[0147] [Example 4]

[0148] See Figure 1 See Figure 2 See Figure 6 In the "slag line position interval uniform erosion prevention mode" state, during the casting process, for example, the operator finds that the long nozzle 1 is leaking and needs to be replaced, and the ladle 8 slide plate control mode is converted from automatic control mode to manual control mode, and the ladle 8 slide plate is closed, see Figure 6 The middle ladle 8 slide plate is converted to automatic control B, and the automatic control mode is started after a delay; the intermediate ladle weight "set value constant" automatic control mode is normally working, and the slide plate opening degree is adjusted to increase the intermediate ladle weight to the dynamic assignment value 26.5 and keep it, when the intermediate ladle actual weight = dynamic assignment value 26.5, the dynamic assignment function of the intermediate ladle weight set value dynamic assignment mode is restored, see Figure 6 The middle ladle 8 slide plate is converted to automatic control B, and the automatic control mode is started after a delay; the intermediate ladle weight "set value constant" automatic control mode is normally working, and the slide plate opening degree is adjusted to increase the intermediate ladle weight to the dynamic assignment value 26.5 and keep it, when the intermediate ladle actual weight = dynamic assignment value 26.5, the dynamic assignment function of the intermediate ladle weight set value dynamic assignment mode is restored, see Figure 6The method is suspended at the C position, and the dynamic setting value updating is resumed; the ladle is replaced, and the next setting value is generated, the next setting value = dynamic assignment + residue line interval weight = 26.5-0.6 = 27.1; trend judgment is performed, the judgment is completed, the next "setting value" calculated is converted into "dynamic assignment", and is directly written; when the intermediate ladle weight "setting value constant" automatic control mode is started, the written "dynamic assignment = 27.1" is directly executed and remains unchanged until the next ladle replacement.

[0149] The present application continuously adjusts the setting value of the intermediate ladle weight, so that the periodic change of the intermediate ladle weight is realized, the molten steel liquid level of the intermediate ladle is periodically raised / lowered at a set speed within the upper / lower limit range, the residue line (width < 20 mm) of the constant weight control method is expanded into a uniform erosion belt (width greater than 200 mm) in the up / down direction, the sintered intermediate ladle dry material powder after melting burns on the surface of the intermediate ladle lining and the stopper residue line during the process of the molten steel liquid level of the intermediate ladle descending, a hot melting repair layer is formed, and the molten steel erosion is offset when the molten steel liquid level of the intermediate ladle rises; the molten steel liquid level height of the intermediate ladle continuously changes, and the relative movement between the residue line and the intermediate ladle refractory always exists, so that the "slag shell" is avoided, and the welding rod problem is eliminated; the intermediate ladle weight fluctuation range is limited, and the cast slab quality and production safety are guaranteed.

Claims

1. A method for dynamically assigning setpoints to improve the lifespan of tundish slag lines, characterized in that, This method adjusts the tundish weight setting value during the rise and fall of the molten steel level in the tundish, and this setting value is dynamically assigned as the next tundish weight setting value. This ensures that the molten steel level in the tundish changes within a specified range, and the slag line forms a uniform vertical erosion zone in the tundish lining, thereby improving the slag line life. The tundish weight setting value and dynamic assignment method are as follows: 1) The calculation formula is: intermediate package weight setting value = dynamic assignment value ± change in intermediate package weight; the initial dynamic assignment value is the initial intermediate package weight at the moment the host computer puts the working mode into operation, and the intermediate package weight setting value obtained in this calculation is used as the dynamic assignment value for the next intermediate package weight setting value calculation. The calculated intermediate pack weight setting must meet the following condition: the setting value is between the upper limit and the lower limit of the optimal intermediate pack weight.

2. The method for dynamically assigning setpoints to improve the lifespan of the tundish slag line according to claim 1, characterized in that, The change in the weight of the intermediate package is the product of the speed of the ascent or descent process and the duration.

3. A method for dynamically assigning setpoints to improve the lifespan of the tundish slag line according to claim 1 or 2, characterized in that, The specific steps are as follows: Determining the initial dynamic assignment The current intermediate package weight at the moment the host computer puts the system into working mode is used as the initial dynamic value. The intermediate package weight setting value calculated from this dynamic value is used as the next dynamic value. And so on, the intermediate package weight setting value calculated each time is the dynamic value for the next intermediate package weight setting value calculation. b. When the working mode is activated, the molten steel is in a rising state; the calculation formula is as follows: The set value of the intermediate bag weight = dynamic assignment + rising speed * duration ① In formula ①: the unit of dynamic assignment is t, the unit of rising speed is t / min, the unit of duration is min, the unit of the set value of the intermediate bag weight is t, and the duration is 10s~30s; When the set value of the tundish weight approaches the upper limit of the optimal tundish weight, the rising state of the molten steel switches to the falling state. The calculation formula is as follows: The set value of the intermediate batch weight = dynamic assignment - descent speed * duration ② In formula ②: the descent speed is in t / min and the duration is 10s to 30s; When the set value of the tundish weight approaches the lower limit of the optimal tundish weight, the molten steel switches from a descending state to an ascending state. The calculation formula is Equation ①.

4. The method for dynamically assigning setpoints to improve the lifespan of the tundish slag line according to claim 3, characterized in that, The formulas for calculating the velocities during the ascent and descent processes are as follows: The upward speed = (the upper limit of the optimal weight of the intermediate bag - the lower limit of the optimal weight of the intermediate bag) / τ ③ The downward speed = the upward speed / n ④ The downward speed ≤ the upward speed ⑤ In formulas ③ to ⑤, τ is the upward time in minutes, and the range of τ is 2 to 4. n is the downward speed coefficient, and the range of n is 1 to 3. The upper limit of the optimal weight of the intermediate bag is t, and the lower limit of the optimal weight of the intermediate bag is t.

5. The method for dynamically assigning setpoints to improve the lifespan of the tundish slag line according to claim 4, characterized in that, The parameters, namely the duration, rise time τ, descent speed coefficient n, optimal upper limit of intermediate package weight, and optimal lower limit of intermediate package weight, are manually transmitted to the host computer.

6. A method for dynamically assigning setpoints to improve the lifespan of tundish slag lines, characterized in that, This method adjusts the tundish weight setting value at certain time intervals, and uses this setting value as the dynamic assignment for the next tundish weight setting value. This causes the molten steel level in the tundish to change within a specified range, resulting in a uniform vertical erosion zone formed by the slag line within the tundish lining. This aims to improve the slag line lifespan. The tundish weight setting value and dynamic assignment method are as follows: 1) The calculation formula is: intermediate ladle weight setting value = dynamic assignment value ± slag line interval weight; the initial dynamic assignment value is the initial intermediate ladle weight at the moment the host computer puts the working mode into operation, and the intermediate ladle weight setting value obtained in this calculation is used as the dynamic assignment value for the next intermediate ladle weight setting value calculation. The calculated intermediate pack weight setting must meet the following condition: the setting value is between the upper limit and the lower limit of the optimal intermediate pack weight.

7. The method for dynamically assigning a set value to improve the service life of the tundish slag line according to claim 6, characterized in that, The specific steps are as follows: Determining the initial "dynamic assignment" The current intermediate package weight at the moment the host computer puts the system into working mode is the initial dynamic assignment. The intermediate package weight setting value calculated from this dynamic assignment is used as the next dynamic assignment value. And so on, the intermediate package weight setting value calculated each time is the dynamic assignment value for the next intermediate package weight setting value calculation. b. When the working mode is activated, the molten steel is in a rising state; the calculation formula is as follows: The set value of the tundish weight = dynamic assignment + slag line interval weight ⑥ In formula ⑥, the unit of dynamic assignment is t; the slag line interval weight ranges from 0.2 to 0.6, and the unit is t; the unit of the set value of the tundish weight is t. When the set value of the tundish weight approaches the upper limit of the optimal tundish weight, the rising state of the molten steel switches to the falling state. The calculation formula is as follows: The set value of the tundish weight = dynamic assignment - slag line interval weight. In formula ⑦, when the molten steel switches from rising to falling, it is a reversal state. At this time, the dynamic assignment is calculated according to the following formula: The dynamic assignment of the reversing state = the dynamic assignment before reversing + the overlapping compensation weight. In formula ⑧, the slag line interval weight = the weight corresponding to the slag line width, the overlapping compensation weight < the slag line interval weight / 2, and the unit of the overlapping compensation weight is t. When the set value of the tundish weight approaches the lower limit of the optimal tundish weight, the molten steel switches from a descending state to an ascending state. The set value of the tundish weight is calculated using formula ⑥; the dynamic assignment value for the reversing state is calculated using formula ⑧.

8. A method for dynamically assigning setpoints to improve the lifespan of the tundish slag line according to claim 1 or 6, characterized in that, The dynamic assignment range of the intermediate package weight setting value satisfies the following conditions: Upper limit range: Dynamically assigned upper limit weight ≤ intermediate package overflow weight — overflow safety margin ⑨ Lower limit range: The dynamic assignment of the lower limit weight is greater than or equal to the minimum weight of the tundish metallurgical function plus the weight of the molten slag in the tundish. In formula ⑨, the upper limit weight is in tons (t), the tundish overflow weight is in tons (t), and the overflow safety margin is in tons (t); in formula ⑩, the lower limit weight is in tons (t), the minimum weight of the tundish metallurgical function is in tons (t), and the weight of the molten slag in the tundish is in tons (t).

9. A method for dynamically assigning setpoints to improve the lifespan of the tundish slag line according to claim 1 or 6, characterized in that, The change trend of the intermediate package weight setting value is a continuous cycle. One cycle includes: rising - reversing - falling - reversing - rising. When the large tank slide is started manually during the cycle, the dynamic assignment of the intermediate package weight setting value is paused and the data is retained. When the automatic control mode is put back into operation, the starting point is the point where the previous cycle was interrupted.

10. A method for dynamically assigning a set value to improve the lifespan of the tundish slag line according to claim 1 or 6, characterized in that, The optimal upper limit of the intermediate package weight = nominal capacity of the intermediate package × 0.9, and the optimal lower limit of the intermediate package weight = nominal capacity of the intermediate package × 0.7.

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