A method for ensuring the rolling cycle of the rolls of a six-high cold rolling mill and for optimizing the working conditions

Abstract

The present application relates to the technical field of cold rolling mill, especially to a method for ensuring the rolling cycle of six-roller cold rolling mill and optimizing the working state, which comprises emulsion lubrication and cooling precise control, reasonable collocation of roller diameter and service cycle, new roller preheating and intelligent distribution of usage rate control, rolling parameter dynamic adjustment with roller state, uniform speed rolling and standard adjustment, ensuring the lubrication condition of roller in the rolling process, reducing the roller wear, making the roller in the appropriate working temperature, avoiding the uneven thermal expansion, influencing the roller working state, also reasonably replacing and collocating according to the cycle and diameter of each roller, adjusting the rolling parameter according to the roller working state, not only ensuring the cycle life of roller, but also significantly improving the full cycle replacement rate of roller, optimizing the working state in the working cycle of roller, achieving the purpose of reducing the roller wear, maintaining the good working state of roller during use, greatly reducing the quality problems of the subsequent process.

Description

Technical Field

[0001] This invention relates to the field of cold rolling mill technology, and in particular to a method for ensuring the rolling cycle of a six-roll cold rolling mill and optimizing its working condition. Background Technology

[0002] The six-roll cold rolling mill is a widely used rolling mill in sheet metal production. With the continuous advancement of cold rolling technology, developing and producing more varieties and higher-standard products has become an inevitable trend. As production difficulty increases, so does the wear and tear on the equipment. The rolling mill rolls are a crucial component of this wear and tear. The greater the rolling difficulty of the product, the greater the wear and tear on the rolls. The higher the product quality requirements, the higher the requirements for the working condition of the rolls.

[0003] Currently, there is a lack of research on reducing wear and tear and maintaining the optimal working condition of cold rolling rolls. Existing technology, such as the article "Production Practice for Reducing Cold Roll Consumption" in the May 2016 issue of *Hebei Metallurgy*, proposes methods to improve roll consumption, including using coated rolls, selecting suitable roll substrates, developing reasonable rolling procedures, and strengthening roll management. However, using coated rolls and selecting suitable roll substrates undoubtedly increases production costs and cannot reliably guarantee the roll's single-use cycle and its working condition within that cycle. This will undoubtedly increase roll consumption and reduce product quality, ultimately leading to increased production costs. Changing the roll material or using coated rolls will indirectly increase production costs significantly. Therefore, there is an urgent need for an operational method that can guarantee the single-use cycle of rolls and extend their optimal working condition within that cycle without changing the roll material or grinding process. Summary of the Invention

[0004] This invention provides a method for ensuring the rolling cycle of a six-roll cold rolling mill and optimizing its working condition. Addressing the problems of unstable roll usage cycles and poor working conditions in most six-roll cold rolling mills, this method, based on ensuring the single-use cycle of the rolls and extending the optimal working condition within that cycle, can reduce roll wear, improve rolling stability, guarantee product quality, and ultimately reduce production costs.

[0005] To achieve the above objectives, the present invention employs the following technical solution: A method for ensuring the rolling cycle of a six-roll cold rolling mill and optimizing its working condition includes the following steps: S1. Roll lubrication and cooling control: Real-time monitoring of the emulsion supply tank level to ensure it is not lower than 50%, control of emulsion temperature and concentration according to the rolling material: silicon steel temperature 42~45℃, concentration 2.2~2.5%, carbon steel temperature 45~50℃, concentration 1.8~2.2%, control of emulsion nozzle failure rate ≤4%, emulsion injection pressure can be manually adjusted; S2. Roll pairing: The work roll and intermediate roll are paired with newly ground rolls and rolls with a service life of less than 80%. The work roll and intermediate roll are matched with the upper limit of their roll diameters, and the matching formula is: (maximum work roll diameter + maximum intermediate roll diameter) - (actual work roll diameter + actual intermediate roll diameter) ≥ (maximum work roll diameter + maximum intermediate roll diameter) × 5%; The lower limit of the roll diameter is matched with the lower limit using the following formula: (Actual working roll diameter + Actual intermediate roll diameter) - (Minimum working roll diameter + Minimum intermediate roll diameter) ≥ (Maximum working roll diameter + Maximum intermediate roll diameter) × 5%; Paired work rolls configuration: Upper work roll diameter - Lower work roll diameter ≤ 0; Paired intermediate rolls configuration: Upper intermediate roll diameter - Lower intermediate roll diameter ≤ 0; S3. Roll preheating and utilization rate allocation: Roll preheating shall be performed according to room temperature and preheating conditions: When there are preheating conditions, i.e. there is no strip in the stand, warm the roll for 5 to 10 minutes when the room temperature is ≥20℃, and warm the roll for 10 to 15 minutes when the room temperature is <20℃; when there are no preheating conditions, i.e. there is strip in the stand, roll at 150m / min for 8 to 10 minutes when the room temperature is ≥20℃, and roll at 150m / min for 10 to 12 minutes when the room temperature is <20℃. The utilization rate of work rolls and intermediate rolls is adjusted according to the reduction rate. When the reduction rate is ≥28%, the work rolls are the main component and the intermediate rolls are the auxiliary component. When the reduction rate is <28%, the work rolls are the auxiliary component and the intermediate rolls are the main component. S4. Dynamic adjustment of rolling parameters: The first roll of a new roll is rolled at an average rolling speed of 70-80%, and the tension is increased by the number of passes. During the last 10-15% of the roll's service life, the speed is reduced and the tension is increased. When the roll's service life exceeds 80%, the bending force of the work roll is reduced and the bending force of the intermediate roll is increased. S5. Rolling process control: Maintain uniform rolling speed.

[0006] Furthermore, the control of emulsion temperature involves starting a cooling cycle when the emulsion needs to be cooled by 6-10°C each time, and adding water when the emulsion needs to be cooled by 3-5°C each time.

[0007] Furthermore, the utilization rate of the work roll and intermediate roll is adjusted according to the reduction rate: when the reduction rate is ≥28%, the work roll utilization rate is 60% and the intermediate roll utilization rate is 40%; when the reduction rate is <28%, the work roll utilization rate is 30% and the intermediate roll utilization rate is 70%.

[0008] Furthermore, the new roll is rolled at an average rolling speed of 70-80%, and the tension is increased by pass. After the first pass, the tension is increased by 10% of the system tension setting value, and after the second pass, the tension is increased by 5% of the system tension setting value.

[0009] Furthermore, the roll operates at a reduced speed and increased tension for the last 10-15% of its service life, with the speed reduction to 70-80% of the average rolling speed, and the tension before the final pass is increased by 20% of the system tension setting.

[0010] Furthermore, when the service life of the roll exceeds 80%, the bending force of the work roll is reduced and the bending force of the intermediate roll is increased. The bending force of the work roll is reduced by 10-15% of the system's calculated value, and the bending force of the intermediate roll is increased by 20-30% of the system's tension setting value.

[0011] Compared with the prior art, the beneficial effects of the present invention are: Ensuring proper lubrication of the rolls during rolling reduces roll wear, keeps the rolls at a suitable operating temperature, and prevents uneven thermal expansion that could affect their working condition. Furthermore, by rationally replacing and matching rolls according to their cycle and diameter, and adjusting rolling parameters based on their working conditions, not only is the roll cycle life guaranteed and the full-cycle replacement rate significantly improved, but the working condition of the rolls within their working cycle is also optimized. This achieves the goal of reducing roll wear while maintaining good working condition during use, greatly reducing quality problems in subsequent processes. Average roll consumption is reduced by 20%, achieving the beneficial effects of reducing production costs and improving product quality. Attached Figure Description

[0012] Figure 1 This is a flowchart of the method of the present invention. Detailed Implementation

[0013] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings: See Figure 1 This is a flowchart of the method of the present invention. The present invention provides a method for ensuring the rolling cycle of a six-roll cold rolling mill and optimizing its working state, comprising the following steps: S1. Roll Lubrication and Cooling Control: The working condition and wear of the rolls are significantly affected by the lubrication and cooling effect. Ensuring the lubrication conditions of the rolls during the rolling process reduces roll wear, keeps the rolls at a suitable working temperature, and avoids uneven thermal expansion that affects the working condition of the rolls. (1) The emulsion supply tank level shall be monitored in real time and shall not be lower than 50%; (2) Control the temperature and concentration of the emulsion according to the rolling material. For silicon steel, the temperature is 42-45℃ and the concentration is 2.2-2.5%. For carbon steel, the temperature is 45-50℃. When the emulsion needs to be cooled by 6-10℃ each time, the cooling cycle is turned on to cool it down. When the emulsion needs to be cooled by 3-5℃ each time, water is added to cool it down. (3) Control the emulsion nozzle failure rate to ≤4%; (4) Ensure the concentration of the emulsion: 2.2-2.5% for silicon steel; 1.8-2.2% for carbon steel; (5) The emulsion spray pressure can be manually adjusted and can be adjusted at any time as needed.

[0014] S2. Replace and match the rolls appropriately according to their cycle and diameter, as follows: (1) It is forbidden to use new work rolls and old intermediate rolls together. New work rolls are new grinding rolls, and old intermediate rolls are rolls with a service life of more than 80%. The roughness and wear of these two types of rolls are very different, which seriously affects the service life and working condition of the rolls. The work rolls and intermediate rolls should be a combination of new grinding rolls and rolls with a service life of less than 80%. (2) The working roll and the intermediate roll are matched with the upper limit of the roll diameter. The matching formula is: (maximum working roll diameter + maximum intermediate roll diameter) - (actual working roll diameter + actual intermediate roll diameter) ≥ (maximum working roll diameter + maximum intermediate roll diameter) × 5%; exceeding this range will result in large rolling force and large friction during use, affecting the working condition. (3) The lower limit of the roller diameter is matched with the lower limit, that is, the matching formula is: (actual working roller diameter + actual intermediate roller diameter) - (minimum working roller diameter + minimum intermediate roller diameter) ≥ (maximum working roller diameter + maximum intermediate roller diameter) × 5%; the roller diameter exceeding this range affects the stiffness of the roller system and leads to poor working condition. (4) Using a combination of coarse upper rolls and fine lower rolls affects the roll balance and can easily lead to roll crossing, which can worsen the working condition. For example, when work rolls or intermediate rolls are used in pairs, the upper roll may be coarser than the lower roll.

[0015] S3, roll preheating and control of utilization rate allocation; Paired work rolls configuration: Upper work roll diameter - Lower work roll diameter ≤ 0; Paired intermediate rolls configuration: Upper intermediate roll diameter - Lower intermediate roll diameter ≤ 0; Preheating newly installed rolls allows them to reach their optimal working condition more quickly and reduces friction during rolling. The so-called roll control utilization rate is the percentage of the total adjustment amount for work rolls and intermediate rolls, achieved by adjusting the roll crown to allow the rolled strip to reach a certain shape index. This indicator directly reflects the wear condition of different rolls, and the distribution of roll control rate will have a significant impact on roll wear and working condition.

[0016] (1) Preheating of the rolls; For machines with preheating conditions (no strip in the frame), warm the rolls for 5-10 minutes if the room temperature is above 20℃; warm for 10-15 minutes if the room temperature is below 20℃. For machines without preheating conditions (with strip in the frame), roll at 150m / min for 8 minutes if the room temperature is above 20℃; roll at 150m / min for 12 minutes if the room temperature is below 20℃.

[0017] (2) Roll adjustment and utilization rate allocation; When the reduction rate is ≥28%, the work roll is the main component and the intermediate roll is the auxiliary component, that is, the utilization rate is adjusted as follows: 60% for the work roll and 40% for the intermediate roll. Adjust the same plate shape index, with 60% adjustment using the work roll and 40% adjustment using the intermediate roll.

[0018] When the reduction rate is less than 28%, the intermediate roller is the main roller and the work roller is the auxiliary roller, that is, the utilization rate is adjusted as follows: 30% for the work roller and 70% for the intermediate roller. Adjust the same plate shape index, with 30% adjustment using the work roll and 70% adjustment using the intermediate roll.

[0019] Avoid prolonged and extensive use and adjustment of a single roll.

[0020] S4. Adjust the rolling parameters according to the working status of the rolls; The working condition of the rolls usually changes with the working time of the rolls, so the rolling parameters should be adjusted appropriately to follow the changes in the working condition of the rolls. For the first roll of a new roll, the rolling speed is 70-80% of the average rolling speed. For the second roll, the normal settings are restored. After the first pass, the tension is increased by 10% of the system tension setting, and after the second pass, the tension is increased by 5% of the system tension setting. The purpose of reducing the rolling speed of the first roll of a new roll is to make the roll wear more uniform and to form a stable and uniform thermal crown. The purpose of increasing the back tension is to reduce the rolling pressure, reduce friction, delay roll wear, and at the same time reduce the risk of roll deviation and roll jamming. The single grinding roll service life is calculated as 100%. For the last 10-15% of the service life, the average rolling speed is 70-80%. Before the final pass, the tension is increased by 20% of the system tension setting. At the end of the roll service life (more than 80% of the service life), the bending force of the work roll is reduced by 10-15% of the system calculation value, and the bending force of the intermediate roll is increased by 30% of the system tension setting value.

[0021] The reason for reducing the bending of the work roll is that the uneven wear on the surface of the work roll is very serious at this time, and the thermal expansion is also extremely uneven. The bending effect is also the worst at this time. Therefore, in order to maintain a stable working state at the end of the roll's service life, the use of bending of the work roll should be reduced. The purpose of increasing the bending of the intermediate roll is to compensate for the reduction of bending of the work roll. Since the intermediate roll does not directly contact the strip, the wear is relatively uniform. At this time, it is more beneficial to replace the bending of the work roll for strip shape control.

[0022] S5. Rolling process control: Fluctuations in rolling speed and unnecessary roll adjustments can affect roll wear and working condition. Therefore, during the rolling process, abnormal speed increases and decreases and unnecessary adjustments (bending rolls, shifting rolls, tilting) should be avoided to maintain uniform rolling speed.

[0023] The following embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operation processes. However, the scope of protection of the present invention is not limited to the following embodiments. Unless otherwise specified, the methods used in the following embodiments are conventional methods.

[0024] Example: The experiment was conducted using a single-stand six-high reversible rolling mill with relatively harsh working conditions. Silicon steel products with relatively high requirements for the rolls were used in the experiment. Specific implementation details and comparisons are shown in the table below: Table 1 Comparative Examples:

[0025] Table 2. Optimization schemes adopted in this invention:

[0026] By collecting and comparing the production data of the two schemes, producing the same output of products (4600t each), under the condition of no accidents, the existing technical scheme replaced a total of 31 sets of working rollers and 10 sets of intermediate rollers, while the optimized scheme replaced a total of 25 sets of working rollers and 8 sets of intermediate rollers, reducing the average roller consumption by 20%.

Claims

1. A method for ensuring the rolling cycle of a six-roll cold rolling mill and optimizing its working condition, characterized in that, Includes the following steps: S1. Roll lubrication and cooling control: Real-time monitoring of the emulsion supply tank level to ensure it is not lower than 50%, control of emulsion temperature and concentration according to the rolling material: silicon steel temperature 42~45℃, concentration 2.2~2.5%, carbon steel temperature 45~50℃, concentration 1.8~2.2%, control of emulsion nozzle failure rate ≤4%, emulsion injection pressure can be manually adjusted; S2. Roll pairing: The work roll and intermediate roll are paired with newly ground rolls and rolls with a service life of less than 80%. The work roll and intermediate roll are matched with the upper limit of their roll diameters, and the matching formula is: (maximum work roll diameter + maximum intermediate roll diameter) - (actual work roll diameter + actual intermediate roll diameter) ≥ (maximum work roll diameter + maximum intermediate roll diameter) × 5%; The lower limit of the roll diameter is matched with the lower limit using the following formula: (Actual working roll diameter + Actual intermediate roll diameter) - (Minimum working roll diameter + Minimum intermediate roll diameter) ≥ (Maximum working roll diameter + Maximum intermediate roll diameter) × 5%; Paired work rolls configuration: Upper work roll diameter - Lower work roll diameter ≤ 0; Paired intermediate rolls configuration: Upper intermediate roll diameter - Lower intermediate roll diameter ≤ 0; S3. Roll preheating and utilization rate allocation: Roll preheating shall be performed according to room temperature and preheating conditions: When there are preheating conditions, i.e. there is no strip in the stand, warm the roll for 5 to 10 minutes when the room temperature is ≥20℃, and warm the roll for 10 to 15 minutes when the room temperature is <20℃; when there are no preheating conditions, i.e. there is strip in the stand, roll at 150m / min for 8 to 10 minutes when the room temperature is ≥20℃, and roll at 150m / min for 10 to 12 minutes when the room temperature is <20℃. The utilization rate of work rolls and intermediate rolls is adjusted according to the reduction rate. When the reduction rate is ≥28%, the work rolls are the main component and the intermediate rolls are the auxiliary component. When the reduction rate is <28%, the work rolls are the auxiliary component and the intermediate rolls are the main component. S4. Dynamic adjustment of rolling parameters: The first roll of a new roll is rolled at an average rolling speed of 70-80%, and the tension is increased by the number of passes. During the last 10-15% of the roll's service life, the speed is reduced and the tension is increased. When the roll's service life exceeds 80%, the bending force of the work roll is reduced and the bending force of the intermediate roll is increased. S5. Rolling process control: Maintain uniform rolling speed.

2. The method for ensuring the rolling cycle of a six-roll cold rolling mill and optimizing its working state according to claim 1, characterized in that, The temperature of the emulsion is controlled by starting the cooling cycle when the emulsion needs to be cooled by 6-10°C each time, and by adding water when the emulsion needs to be cooled by 3-5°C each time.

3. The method for ensuring the rolling cycle of a six-roll cold rolling mill and optimizing its working state according to claim 1, characterized in that, The utilization rate of the work roll and intermediate roll is adjusted according to the reduction rate: when the reduction rate is ≥28%, the work roll utilization rate is 60% and the intermediate roll utilization rate is 40%; when the reduction rate is <28%, the work roll utilization rate is 30% and the intermediate roll utilization rate is 70%.

4. The method for ensuring the rolling cycle of a six-roll cold rolling mill and optimizing its working state according to claim 1, characterized in that, The new roll is rolled at an average rolling speed of 70-80%, and the tension is increased by the number of passes. After the first pass, the tension is increased by 10% of the system tension setting value, and after the second pass, the tension is increased by 5% of the system tension setting value.

5. The method for ensuring the rolling cycle of a six-roll cold rolling mill and optimizing its working state according to claim 1, characterized in that, The rolls are operated at reduced speed and tension increased for the last 10-15% of their service life, with the speed reduced to 70-80% of the average rolling speed. The tension is increased by 20% of the system tension setting before the final pass.

6. The method for ensuring the rolling cycle of a six-roll cold rolling mill and optimizing its working state according to claim 1, characterized in that, When the service life of the roll exceeds 80%, reduce the bending force of the work roll and increase the bending force of the intermediate roll. The bending force of the work roll is reduced by 10-15% of the system's calculated value, and the bending force of the intermediate roll is increased by 20-30% of the system's tension setting value.

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