A method for controlling the temperature of molten aluminum during aluminum alloy casting and rolling

Abstract

The present invention relates to the technical field of aluminum alloy casting and rolling, and specifically to a method for controlling the temperature of aluminum liquid in the aluminum alloy casting and rolling process. The method comprises the following steps: a heating method for the aluminum liquid in a holding furnace and a temperature control range for the aluminum liquid in a casting and rolling section are formulated; the heating power is continuously adjusted and judged according to the temperature change of the aluminum liquid in the holding furnace, thereby achieving stable control of the aluminum liquid temperature in the holding furnace and the output aluminum liquid temperature of the holding furnace, avoiding large fluctuations in the aluminum liquid temperature in the holding furnace due to rapid changes in the furnace gas temperature, and reducing the influence of the holding heating process on overburning of the aluminum liquid; standardizing the temperature control range of each link, so that the temperature of the aluminum liquid in the holding furnace and the aluminum liquid in subsequent links can be kept stable, effectively avoiding the influence of temperature fluctuations in subsequent casting and rolling processes on the quality of cast and rolled products, and significantly reducing the generation of uneven grain structure and coarse grain defects in the cast and rolled products; and eliminating the frequent start and stop of silicon carbon rods in a heating device in the holding furnace, thereby extending the service life of the silicon carbon rods and reducing production costs.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloy casting and rolling, and in particular to a method for controlling the temperature of aluminum liquid during the aluminum alloy casting and rolling process. Background Art

[0002] Melt temperature is an important process parameter in the aluminum alloy casting and rolling process. The rationality of the melt temperature setting is related to the quality of the product, especially the overburning of the melt, which is also related to the burn loss of the product. The temperature control method plays a decisive role in the precise and stable control of the aluminum liquid temperature.

[0003] The traditional temperature control method requires the operator to frequently measure the temperature of the molten aluminum in the holding furnace. When the temperature falls below the process control lower limit, high-power heating is activated, causing the molten aluminum to heat up rapidly. When the molten aluminum reaches the process upper limit, the heating power is reduced based on experience, and the furnace enters the holding mode. When the temperature falls below the process lower limit, heating is resumed. This traditional operating method has the following main shortcomings: First, the holding furnace is frequently heated and held using empirical methods. However, empirical holding methods are not completely reliable, and the temperature fluctuates continuously, resulting in poor stability. Second, high-power heating causes the high-temperature furnace gas to overheat the surface temperature of the molten aluminum in the holding furnace, causing serious overheating of the molten aluminum and affecting the internal quality of the cast and rolled products. Third, frequent temperature measurements result in frequent furnace door openings, consuming a large number of handheld thermocouples, increasing the labor intensity of the operator, and causing a large loss of heat from the holding furnace, resulting in energy waste and environmental damage. Summary of the Invention

[0004] The object of the present invention is to provide a method for controlling the temperature of molten aluminum during the casting and rolling process of aluminum alloys, which continuously adjusts and judges the heating power according to the temperature change of the molten aluminum in the holding furnace, thereby achieving stable control of the molten aluminum temperature in the holding furnace and the output temperature of the molten aluminum in the holding furnace, avoiding large fluctuations in the molten aluminum temperature in the holding furnace due to rapid changes in the furnace gas temperature, and reducing the impact of the holding heating process on overburning of the molten aluminum.

[0005] To solve the above technical problems, the present invention provides a method for controlling the temperature of molten aluminum during aluminum alloy casting and rolling, comprising the following steps:

[0006] S1. Formulate a method for raising the temperature of aluminum liquid in the holding furnace:

[0007] S1.1. When the difference between the actual temperature of the aluminum liquid at the furnace eye and the set temperature is between -5℃ and 0℃, the furnace eye temperature is controlled and the heating power is adjusted according to the percentage output. The temperature difference is accurate to an integer. The correspondence between the difference between the actual temperature of the aluminum liquid at the furnace eye and the set temperature and the heating power percentage is as follows:

[0008] S1.1.1. When the difference between the actual temperature of the aluminum liquid at the furnace mouth and the set temperature is -5°C, the corresponding heating power percentage is 100%;

[0009] S1.1.2. When the difference between the actual temperature of the aluminum liquid at the furnace mouth and the set temperature is -4°C, the corresponding heating power percentage is 90%;

[0010] S1.1.3. When the difference between the actual temperature of the aluminum liquid at the furnace mouth and the set temperature is -3°C, the corresponding heating power percentage is 80%;

[0011] S1.1.4. When the difference between the actual temperature of the aluminum liquid at the furnace mouth and the set temperature is -2°C, the corresponding heating power percentage is 70%;

[0012] S1.1.5. When the difference between the actual temperature of the aluminum liquid at the furnace mouth and the set temperature is -1°C, the corresponding heating power percentage is 60%;

[0013] S1.1.6. When the difference between the actual temperature of the aluminum liquid at the furnace mouth and the set temperature is 0°C, the corresponding heating power percentage is 50%;

[0014] S1.2. When the actual temperature of the aluminum liquid at the furnace eye is lower than the set temperature by more than 5°C or the actual temperature of the aluminum liquid at the furnace eye is higher than the set temperature, the furnace gas temperature is controlled and the heating power is matched and output according to the temperature difference between the actual furnace gas temperature and the set temperature. The correspondence between the temperature difference between the actual furnace gas temperature and the set temperature and the heating power percentage is as follows:

[0015] S1.2.1. When the temperature difference between the actual furnace gas temperature and the set temperature is -5°C, the corresponding heating power percentage is 100%;

[0016] S1.2.2. When the temperature difference between the actual furnace gas temperature and the set temperature is -4°C, the corresponding heating power percentage is 90%;

[0017] S1.2.3. When the temperature difference between the actual furnace gas temperature and the set temperature is -3°C, the corresponding heating power percentage is 80%;

[0018] S1.2.4. When the temperature difference between the actual furnace gas temperature and the set temperature is -2°C, the corresponding heating power percentage is 70%;

[0019] S1.2.5. When the temperature difference between the actual furnace gas temperature and the set temperature is -1°C, the corresponding heating power percentage is 60%;

[0020] S1.2.6. When the temperature difference between the actual furnace gas temperature and the set temperature is 0°C or the actual furnace gas temperature is higher than the set temperature, the corresponding heating power percentage is 50%;

[0021] S2. Determine the temperature control range of aluminum liquid in the casting and rolling section:

[0022] S2.1. For Series 1 alloys, the holding furnace gas temperature setting range is 805°C-815°C; the holding furnace aluminum liquid temperature control range is 725°C-735°C; the holding furnace eye aluminum liquid target temperature is 720°C; the holding furnace eye aluminum liquid temperature control range is 720°C±5°C; the degassing box temperature setting range is 705°C-715°C; the filter box melt temperature setting range is 700°C-705°C; the front box melt target temperature is 690°C±2°C;

[0023] S2.2. For 3 series alloys, the holding furnace gas temperature setting range is 810°C-820°C; the holding furnace aluminum liquid temperature control range is 730°C-740°C; the holding furnace eye aluminum liquid target temperature is 725°C; the holding furnace eye aluminum liquid temperature control range is 725°C±5°C; the degassing box temperature setting value is 710°C-720°C; the filter box melt temperature setting value is 705°C-710°C; the front box melt target temperature is 695°C±2°C;

[0024] S2.3. For 8 series alloys, the holding furnace gas temperature setting range is 815°C-825°C; the holding furnace aluminum liquid temperature control range is 735°C-745°C; the holding furnace eye aluminum liquid target temperature is 730°C; the holding furnace eye aluminum liquid temperature control range is 730°C±5°C; the degassing box temperature setting range is 715°C-725°C; the filter box melt temperature setting range is 710°C-715°C; the front box melt target temperature is 700°C±2°C;

[0025] S2.4. The temperature setting rules for the casting and rolling sections are as follows: the holding furnace gas temperature setting range == melt temperature + 80°C; the holding furnace aluminum liquid temperature control range = holding furnace eye melt target temperature + 5-15°C; the holding furnace eye aluminum liquid temperature control range = degassing box melt temperature setting value + 10°C; the degassing box temperature setting value = filtered melt temperature setting value + 5-10°C; the filtered box melt temperature setting value = front box melt target temperature + 10-15°C; the front box melt target temperature is the front box melt target temperature for 1-series alloys, 3-series alloys, and 8-series alloys recorded in steps S2.1, S2.2, and S2.3.

[0026] Furthermore, in step S1, when the casting and rolling mill is shut down, the furnace eye thermocouple cannot measure the actual temperature of the aluminum liquid, and the furnace gas temperature is controlled. The furnace gas temperature setting value is adjusted according to the expected downtime. The normal temperature setting value is restored one hour before the plate is erected. The corresponding relationship between the expected downtime and the furnace gas temperature setting value is as follows:

[0027] If the expected downtime is less than 4 hours, the set temperature is 760℃-780℃;

[0028] If the expected downtime is less than 4 hours to 8 hours, the set temperature is 740℃-760℃;

[0029] If the downtime is expected to be more than 8 hours, the set temperature is 720℃-740℃.

[0030] Furthermore, in step S1, the temperature control of the aluminum liquid in the insulation furnace adopts a bipolar temperature control mode of furnace eye temperature control combined with furnace gas temperature control, and can automatically switch the control. The heat source of the bipolar temperature control mode is electric heating; in the furnace gas temperature control mode, when the aluminum liquid temperature at the furnace eye mouth is lower than the set temperature of 0-5°C, the furnace eye temperature control mode is automatically entered; when the aluminum liquid temperature at the furnace eye mouth is greater than the set value or the temperature difference is greater than -5°C in the furnace eye temperature control mode, the furnace gas temperature control mode is automatically entered; in the furnace gas temperature control mode, the temperature rise is stopped when the furnace eye temperature is higher than the target value.

[0031] Furthermore, except for refining operations, the furnace door of the insulation furnace is prohibited from being opened at all times to prevent heat loss from the furnace gas, manual power outages are prohibited, human participation in temperature control is eliminated, and manual temperature measurement is not performed.

[0032] The beneficial effects of the present invention are:

[0033] The present invention fully considers the characteristics of temperature hysteresis and thermal inertia of industrial furnaces. The temperature control of the aluminum liquid in the holding furnace adopts a bipolar temperature control mode of furnace eye temperature control combined with furnace gas temperature control. The two can automatically switch control according to the temperature difference between the furnace eye temperature and the target temperature. The heating power is continuously adjusted and judged according to the temperature change of the aluminum liquid in the holding furnace, thereby achieving stable control of the aluminum liquid temperature in the holding furnace and the aluminum liquid output temperature of the holding furnace, avoiding large fluctuations in the aluminum liquid temperature in the holding furnace due to rapid changes in the furnace gas temperature, and reducing the impact of the holding heating process on overburning of the aluminum liquid.

[0034] By setting a reasonable temperature gradient for the front box, filter box and degassing box and standardizing the temperature control range of each link, the temperature of the aluminum liquid in the holding furnace and the subsequent links can be kept stable, effectively avoiding the impact of temperature fluctuations in the subsequent casting and rolling process on the quality of the cast and rolled products, and significantly reducing the occurrence of uneven grain structure and coarse grain defects in the cast and rolled products;

[0035] By adopting the bipolar temperature control automatic switching control mode of furnace eye temperature control and furnace gas temperature control, the output power is reasonably set, the heating power of the holding furnace is adjusted, the furnace gas temperature and the aluminum liquid temperature at the furnace eye port communicate with each other and limit each other, thus achieving precise control of the aluminum industry temperature in the holding furnace;

[0036] As the liquid level in the furnace changes, it automatically matches the optimal furnace gas temperature, realizes intelligent judgment of temperature trend, eliminates delay, avoids overburning of aluminum liquid surface at low liquid level, and improves product quality; puts an end to the frequent start and stop of silicon carbon rods in the heating device of the holding furnace, extends the service life of silicon carbon rods, and reduces production costs. DETAILED DESCRIPTION

[0037] The present invention provides a method for controlling the temperature of molten aluminum during aluminum alloy casting and rolling, comprising the following steps:

[0038] S1. Formulate a method for raising the temperature of aluminum liquid in the holding furnace:

[0039] S1.1. When the difference between the actual temperature of the aluminum liquid at the furnace eye and the set temperature is between -5℃ and 0℃, the furnace eye temperature is controlled and the heating power is adjusted according to the percentage output. The temperature difference is accurate to an integer. The correspondence between the difference between the actual temperature of the aluminum liquid at the furnace eye and the set temperature and the heating power percentage is as follows:

[0040] S1.1.1. When the difference between the actual temperature of the aluminum liquid at the furnace mouth and the set temperature is -5°C, the corresponding heating power percentage is 100%;

[0041] S1.1.2. When the difference between the actual temperature of the aluminum liquid at the furnace mouth and the set temperature is -4°C, the corresponding heating power percentage is 90%;

[0042] S1.1.3. When the difference between the actual temperature of the aluminum liquid at the furnace mouth and the set temperature is -3°C, the corresponding heating power percentage is 80%;

[0043] S1.1.4. When the difference between the actual temperature of the aluminum liquid at the furnace mouth and the set temperature is -2°C, the corresponding heating power percentage is 70%;

[0044] S1.1.5. When the difference between the actual temperature of the aluminum liquid at the furnace mouth and the set temperature is -1°C, the corresponding heating power percentage is 60%;

[0045] S1.1.6. When the difference between the actual temperature of the aluminum liquid at the furnace mouth and the set temperature is 0°C, the corresponding heating power percentage is 50%;

[0046] S1.2. When the actual temperature of the aluminum liquid at the furnace eye is lower than the set temperature by more than 5°C or the actual temperature of the aluminum liquid at the furnace eye is higher than the set temperature, the furnace gas temperature is controlled and the heating power is matched and output according to the temperature difference between the actual furnace gas temperature and the set temperature. The correspondence between the temperature difference between the actual furnace gas temperature and the set temperature and the heating power percentage is as follows:

[0047] S1.2.1. When the temperature difference between the actual furnace gas temperature and the set temperature is -5°C, the corresponding heating power percentage is 100%;

[0048] S1.2.2. When the temperature difference between the actual furnace gas temperature and the set temperature is -4°C, the corresponding heating power percentage is 90%;

[0049] S1.2.3. When the temperature difference between the actual furnace gas temperature and the set temperature is -3°C, the corresponding heating power percentage is 80%;

[0050] S1.2.4. When the temperature difference between the actual furnace gas temperature and the set temperature is -2°C, the corresponding heating power percentage is 70%;

[0051] S1.2.5. When the temperature difference between the actual furnace gas temperature and the set temperature is -1°C, the corresponding heating power percentage is 60%;

[0052] S1.2.6. When the temperature difference between the actual furnace gas temperature and the set temperature is 0°C or the actual furnace gas temperature is higher than the set temperature, the corresponding heating power percentage is 50%;

[0053] S2. Determine the temperature control range of aluminum liquid in the casting and rolling section:

[0054] S2.1. For Series 1 alloys, the holding furnace gas temperature setting range is 805°C-815°C; the holding furnace aluminum liquid temperature control range is 725°C-735°C; the holding furnace eye aluminum liquid target temperature is 720°C; the holding furnace eye aluminum liquid temperature control range is 720°C±5°C; the degassing box temperature setting range is 705°C-715°C; the filter box melt temperature setting range is 700°C-705°C; the front box melt target temperature is 690°C±2°C;

[0055] S2.2. For 3 series alloys, the holding furnace gas temperature setting range is 810°C-820°C; the holding furnace aluminum liquid temperature control range is 730°C-740°C; the holding furnace eye aluminum liquid target temperature is 725°C; the holding furnace eye aluminum liquid temperature control range is 725°C±5°C; the degassing box temperature setting value is 710°C-720°C; the filter box melt temperature setting value is 705°C-710°C; the front box melt target temperature is 695°C±2°C;

[0056] S2.3. For 8 series alloys, the holding furnace gas temperature setting range is 815°C-825°C; the holding furnace aluminum liquid temperature control range is 735°C-745°C; the holding furnace eye aluminum liquid target temperature is 730°C; the holding furnace eye aluminum liquid temperature control range is 730°C±5°C; the degassing box temperature setting range is 715°C-725°C; the filter box melt temperature setting range is 710°C-715°C; the front box melt target temperature is 700°C±2°C;

[0057] S2.4. The temperature setting rules for the casting and rolling sections are as follows: the holding furnace gas temperature setting range == melt temperature + 80°C; the holding furnace aluminum liquid temperature control range = holding furnace eye melt target temperature + 5-15°C; the holding furnace eye aluminum liquid temperature control range = degassing box melt temperature setting value + 10°C; the degassing box temperature setting value = filtered melt temperature setting value + 5-10°C; the filtered box melt temperature setting value = front box melt target temperature + 10-15°C; the front box melt target temperature is the front box melt target temperature for 1-series alloys, 3-series alloys, and 8-series alloys recorded in steps S2.1, S2.2, and S2.3.

[0058] Furthermore, in step S1, when the casting and rolling mill is shut down, the furnace eye thermocouple cannot measure the actual temperature of the aluminum liquid, and the furnace gas temperature is controlled. The furnace gas temperature setting value is adjusted according to the expected downtime. The normal temperature setting value is restored one hour before the plate is erected. The corresponding relationship between the expected downtime and the furnace gas temperature setting value is as follows:

[0059] If the expected downtime is less than 4 hours, the set temperature is 760℃-780℃;

[0060] If the expected downtime is less than 4 hours to 8 hours, the set temperature is 740℃-760℃;

[0061] If the downtime is expected to be more than 8 hours, the set temperature is 720℃-740℃.

[0062] Furthermore, in step S1, the temperature control of the aluminum liquid in the insulation furnace adopts a bipolar temperature control mode of furnace eye temperature control combined with furnace gas temperature control, and can automatically switch the control. The heat source of the bipolar temperature control mode is electric heating; in the furnace gas temperature control mode, when the aluminum liquid temperature at the furnace eye mouth is lower than the set temperature of 0-5°C, the furnace eye temperature control mode is automatically entered; when the aluminum liquid temperature at the furnace eye mouth is greater than the set value or the temperature difference is greater than -5°C in the furnace eye temperature control mode, the furnace gas temperature control mode is automatically entered; in the furnace gas temperature control mode, the temperature rise is stopped when the furnace eye temperature is higher than the target value.

[0063] Furthermore, except for refining operations, the furnace door of the insulation furnace is prohibited from being opened at all times to prevent heat loss from the furnace gas, manual power outages are prohibited, human participation in temperature control is eliminated, and manual temperature measurement is not performed.

[0064] Example 1:

[0065] During online casting and rolling production of 1100 aluminum alloy, the holding furnace molten aluminum temperature was 733°C and the furnace eye opening temperature was 719°C. The PLC program used the furnace eye temperature control. The molten aluminum temperature in the smelting furnace was high. After the furnace was poured, the holding furnace molten aluminum temperature rose to 738°C and the furnace eye opening temperature was 727°C. This exceeded the control range of 715-725°C for the furnace eye temperature control mode. The PLC program automatically switched to furnace gas temperature control mode. At this time, the furnace gas temperature was 821°C and needed to be controlled to 805-815°C. The holding furnace heating power was reduced to 50% until the holding furnace eye opening temperature reached the range of 715-720°C. The PLC program then automatically switched from furnace gas temperature control mode to furnace eye temperature control mode, maintaining the holding furnace heating power between 60-80% and maintaining the furnace eye opening temperature within the range of 715-720°C.

[0066] The temperature of the aluminum liquid at the furnace mouth is continuously maintained in the range of 715-718℃, the temperature of the aluminum liquid in the degassing box can be controlled at 705-710℃, the temperature of the aluminum liquid in the filter box can be controlled at 700-702℃, and the temperature of the front box can be controlled at 690-692℃.

[0067] According to the production plan, the casting and rolling mill needs to be shut down for 6 hours. After the shutdown, the PLC temperature control program of the holding furnace manually enters the furnace gas temperature control mode and manually sets the holding furnace gas setpoint to 750°C. The aluminum liquid temperature is controlled within the range of 720±5, and the aluminum liquid temperature is appropriately lowered to prevent overburning. One hour before the plate is erected, the holding furnace gas temperature is restored to the normal temperature setpoint of 805°C. The aluminum liquid temperature in the holding furnace is restored to the normal production temperature range of 725-735°C before production can resume.

[0068] Example 2:

[0069] In online casting and rolling production of 3003 aluminum alloy, the holding furnace molten aluminum temperature was 737°C and the furnace eye opening temperature was 722°C. The PLC program used the furnace eye temperature control. The molten aluminum temperature in the smelting furnace was high. After the furnace was poured, the holding furnace molten aluminum temperature rose to 741°C and the furnace eye opening temperature was 732°C. This exceeded the control range of 720-730°C for the furnace eye temperature control mode. The PLC program automatically switched to furnace gas temperature control mode. At this time, the furnace gas temperature was 825°C and needed to be controlled to 810-820°C. The holding furnace heating power was reduced to 50% until the holding furnace eye opening temperature reached the range of 720-730°C. The PLC program automatically switched from furnace gas temperature control mode to furnace eye temperature control mode, maintaining the holding furnace heating power between 60-90% and maintaining the furnace eye opening temperature within the range of 720-725°C.

[0070] The temperature of the aluminum liquid at the furnace mouth is continuously maintained in the range of 720-725℃, the temperature of the aluminum liquid in the degassing box is controlled at 710-715℃, the temperature of the aluminum liquid in the filter box is controlled at 705-710℃, and the temperature of the front box is controlled at 695-697℃.

[0071] According to the production plan, the casting and rolling mill needs to be shut down for 3 hours. After the shutdown, the PLC temperature control program of the holding furnace manually enters the furnace gas temperature control mode and manually sets the holding furnace gas setpoint to 770°C. The aluminum liquid temperature is controlled within the range of 725±5, and the aluminum liquid temperature is appropriately lowered to prevent overburning. One hour before the plate is erected, the holding furnace gas temperature is restored to the normal temperature setpoint of 810°C. The aluminum liquid temperature in the holding furnace is restored to the normal production temperature range of 730-740°C before production can resume.

[0072] Example 3:

[0073] In online casting and rolling production of 8011 aluminum alloy, the holding furnace molten aluminum temperature was 741°C and the furnace eye opening temperature was 728°C. The PLC program used the furnace eye temperature control. The molten aluminum temperature in the smelting furnace was high. After the furnace was poured, the holding furnace molten aluminum temperature rose to 748°C and 737°C at the furnace eye opening, exceeding the control range of 725-735°C for the furnace eye temperature control mode. The PLC program automatically switched to furnace gas temperature control mode. At this time, the furnace gas temperature was 832°C and needed to be controlled to 815-825°C. The holding furnace heating power was reduced to 50% until the holding furnace eye opening temperature reached the range of 725-735°C. The PLC program then automatically switched from furnace gas temperature control mode to furnace eye temperature control mode, maintaining the holding furnace heating power between 60-90% and maintaining the holding furnace eye opening temperature within the range of 725-730°C.

[0074] The temperature of the aluminum liquid at the furnace eye is continuously maintained in the range of 725-730℃, the temperature of the aluminum liquid in the degassing box is controlled at 715-720℃, the temperature of the aluminum liquid in the filter box is controlled at 710-715℃, and the temperature of the front box is controlled at 698-700℃.

[0075] According to the production plan, the casting and rolling mill needs to be shut down for 10 hours. After the shutdown, the PLC temperature control program of the holding furnace manually enters the furnace gas temperature control mode and manually sets the holding furnace gas setpoint to 730°C. The aluminum liquid temperature is controlled within the range of 715±5, and the aluminum liquid temperature is appropriately lowered to prevent overburning. One hour before the plate is erected, the holding furnace gas temperature is restored to the normal temperature setpoint of 815°C. The aluminum liquid temperature in the holding furnace is restored to the normal production temperature range of 735-745°C before production can resume.

[0076] This invention fully considers the temperature hysteresis and thermal inertia characteristics of industrial furnaces. The holding furnace aluminum liquid temperature control adopts a bipolar temperature control mode that combines furnace eye temperature control with furnace gas temperature control. The two modes automatically switch control based on the temperature difference between the furnace eye temperature and the target temperature, replacing the traditional manual operation method based on personal experience. The heating power is continuously adjusted and judged based on the changes in the holding furnace aluminum liquid temperature, thereby achieving stable control of the holding furnace aluminum liquid temperature and the holding furnace aluminum liquid output temperature. This avoids large fluctuations in the aluminum liquid temperature in the holding furnace due to rapid changes in furnace gas temperature and reduces the impact of the holding heating process on the aluminum liquid overheating.

[0077] By setting reasonable temperature gradients for the front box, filter box and degassing box and standardizing the temperature control range of each link, the temperature of the molten aluminum in the holding furnace and the subsequent links can be kept stable, effectively avoiding the impact of temperature fluctuations in the subsequent casting and rolling process on the quality of cast and rolled products, and significantly reducing the uneven grain structure and coarse grain defects inside the cast and rolled products.

[0078] By adopting the bipolar temperature control automatic switching control mode of furnace eye temperature control and furnace gas temperature control, reasonably setting the PLC program to adjust the output power in the bipolar temperature control mode, adjusting the heating power of the holding furnace, and the furnace gas temperature and the aluminum liquid temperature at the furnace eye communicate with each other and restrict each other, precise control of the aluminum industry temperature in the holding furnace is achieved.

[0079] The system automatically matches the optimal furnace gas temperature as the liquid level in the furnace changes, enabling intelligent temperature trend analysis and eliminating time delays. This prevents overheating of the aluminum liquid surface at low liquid levels, improving product quality. It also eliminates the frequent start and stop of the silicon carbon rods in the heating device of the holding furnace, extending their service life and reducing production costs.

Claims

1. A method for controlling the temperature of molten aluminum during aluminum alloy casting and rolling, characterized in that: The following steps are included: S1. Formulate a method for raising the temperature of aluminum liquid in the holding furnace: S1.

1. When the difference between the actual temperature of the aluminum liquid at the furnace eye and the set temperature is between -5℃ and 0℃, the furnace eye temperature is controlled and the heating power is adjusted according to the percentage output. The temperature difference is accurate to an integer. The correspondence between the difference between the actual temperature of the aluminum liquid at the furnace eye and the set temperature and the heating power percentage is as follows: S1.1.

1. When the difference between the actual temperature of the aluminum liquid at the furnace mouth and the set temperature is -5°C, the corresponding heating power percentage is 100%; S1.1.

2. When the difference between the actual temperature of the aluminum liquid at the furnace mouth and the set temperature is -4°C, the corresponding heating power percentage is 90%; S1.1.

3. When the difference between the actual temperature of the aluminum liquid at the furnace mouth and the set temperature is -3°C, the corresponding heating power percentage is 80%; S1.1.

4. When the difference between the actual temperature of the aluminum liquid at the furnace mouth and the set temperature is -2°C, the corresponding heating power percentage is 70%; S1.1.

5. When the difference between the actual temperature of the aluminum liquid at the furnace mouth and the set temperature is -1°C, the corresponding heating power percentage is 60%; S1.1.

6. When the difference between the actual temperature of the aluminum liquid at the furnace mouth and the set temperature is 0°C, the corresponding heating power percentage is 50%; S1.

2. When the actual temperature of the aluminum liquid at the furnace eye is lower than the set temperature by more than 5°C or the actual temperature of the aluminum liquid at the furnace eye is higher than the set temperature, the furnace gas temperature is controlled and the heating power is matched and output according to the temperature difference between the actual furnace gas temperature and the set temperature. The correspondence between the temperature difference between the actual furnace gas temperature and the set temperature and the heating power percentage is as follows: S1.2.

1. When the temperature difference between the actual furnace gas temperature and the set temperature is -5°C, the corresponding heating power percentage is 100%; S1.2.

2. When the temperature difference between the actual furnace gas temperature and the set temperature is -4°C, the corresponding heating power percentage is 90%; S1.2.

3. When the temperature difference between the actual furnace gas temperature and the set temperature is -3°C, the corresponding heating power percentage is 80%; S1.2.

4. When the temperature difference between the actual furnace gas temperature and the set temperature is -2°C, the corresponding heating power percentage is 70%; S1.2.

5. When the temperature difference between the actual furnace gas temperature and the set temperature is -1°C, the corresponding heating power percentage is 60%; S1.2.

6. When the temperature difference between the actual furnace gas temperature and the set temperature is 0°C or the actual furnace gas temperature is higher than the set temperature, the corresponding heating power percentage is 50%; S2. Determine the temperature control range of aluminum liquid in the casting and rolling section: S2.

1. For Series 1 alloys, the holding furnace gas temperature setting range is 805°C-815°C; the holding furnace aluminum liquid temperature control range is 725°C-735°C; the holding furnace eye aluminum liquid target temperature is 720°C; the holding furnace eye aluminum liquid temperature control range is 720°C±5°C; the degassing box temperature setting range is 705°C-715°C; the filter box melt temperature setting range is 700°C-705°C; the front box melt target temperature is 690°C±2°C; S2.

2. For 3 series alloys, the holding furnace gas temperature setting range is 810°C-820°C; the holding furnace aluminum liquid temperature control range is 730°C-740°C; the holding furnace eye aluminum liquid target temperature is 725°C; the holding furnace eye aluminum liquid temperature control range is 725°C±5°C; the degassing box temperature setting value is 710°C-720°C; the filter box melt temperature setting value is 705°C-710°C; the front box melt target temperature is 695°C±2°C; S2.

3. For 8 series alloys, the holding furnace gas temperature setting range is 815°C-825°C; the holding furnace aluminum liquid temperature control range is 735°C-745°C; the holding furnace eye aluminum liquid target temperature is 730°C; the holding furnace eye aluminum liquid temperature control range is 730°C±5°C; the degassing box temperature setting range is 715°C-725°C; the filter box melt temperature setting range is 710°C-715°C; the front box melt target temperature is 700°C±2°C; S2.

4. The temperature setting rules for the casting and rolling sections are as follows: the holding furnace gas temperature setting range == melt temperature + 80°C; the holding furnace aluminum liquid temperature control range = holding furnace eye melt target temperature + 5-15°C; the holding furnace eye aluminum liquid temperature control range = degassing box melt temperature setting value + 10°C; the degassing box temperature setting value = filtered melt temperature setting value + 5-10°C; the filtered box melt temperature setting value = front box melt target temperature + 10-15°C; the front box melt target temperature is the front box melt target temperature for 1-series alloys, 3-series alloys, and 8-series alloys recorded in steps S2.1, S2.2, and S2.

3.

2. The method for controlling the temperature of molten aluminum during aluminum alloy casting and rolling according to claim 1, wherein: In step S1, when the casting and rolling mill is shut down, the furnace eye thermocouple cannot measure the actual temperature of the aluminum liquid, and the furnace gas temperature is controlled. The furnace gas temperature setting value is adjusted according to the expected downtime. The normal temperature setting value is restored one hour before the plate is erected. The corresponding relationship between the expected downtime and the furnace gas temperature setting value is as follows: If the expected downtime is less than 4 hours, the set temperature is 760℃-780℃; If the expected downtime is less than 4 hours to 8 hours, the set temperature is 740℃-760℃; If the downtime is expected to be more than 8 hours, the set temperature is 720℃-740℃.

3. The method for controlling the temperature of molten aluminum during aluminum alloy casting and rolling according to claim 1, wherein: Step S1: The temperature control of the aluminum liquid in the holding furnace adopts a bipolar temperature control mode that combines furnace eye temperature control with furnace gas temperature control, and can automatically switch the control. The heat source of the bipolar temperature control mode is electric heating. In the furnace gas temperature control mode, when the aluminum liquid temperature at the furnace eye is lower than the set temperature of 0-5°C, the furnace eye temperature control mode is automatically entered. When the aluminum liquid temperature at the furnace eye is greater than the set value or the temperature difference is greater than -5°C in the furnace eye temperature control mode, the furnace gas temperature control mode is automatically entered. In the furnace gas temperature control mode, the temperature rise is stopped when the furnace eye temperature is higher than the target value.

4. The method for controlling the temperature of molten aluminum during aluminum alloy casting and rolling according to claim 1, wherein: Except for refining operations, the furnace door of the insulation furnace is prohibited from being opened at all times to prevent heat loss from the furnace gas. It is prohibited to manually cut off the power, prevent human participation in temperature control, and do not perform manual temperature measurement.