A multi-stage gradient drying and anti-oxidation treatment method and system for a continuous electrotinning steel sheet production line

Abstract

The application discloses a kind of multistage gradient drying and anti-oxidation treatment method and system of continuous electroplated tin sheet production line, belong to metallurgical heat treatment technical field.The method is sequentially arranged along the strip steel running direction three processing stages of edge automatic tracking air knife, integral pressurized air knife and steam air knife.First, the moisture of strip steel edge is accurately removed through automatic tracking technology;Second, the free water on the whole plate is removed through integral air knife;Finally, through the injection of superheated steam mixed gas, the residual moisture is completely evaporated at high temperature and an inert protective layer is formed on the surface of the strip steel, preventing tin layer oxidation.The application solves the "black edge" defect caused by incomplete drying of the edge in the traditional drying process and the high temperature oxidation problem, with the advantages of high drying efficiency, stable product quality and high automation degree.

Description

Technical Field

[0001] This invention belongs to the field of continuous hot-dip galvanizing / tin production technology in the metallurgical industry, and particularly relates to a multi-stage gradient drying and anti-oxidation treatment method and system for a continuous electroplating tin thin steel plate production line. Background Technology

[0002] In high-speed continuous tin plating production of strip steel, the surface of the strip steel after chemical treatments such as pickling, alkaline washing, electroplating, or passivation is covered with a large amount of cleaning water and a small amount of solution residue. Before entering the next process, the moisture and solution on the surface of the strip steel must be thoroughly removed. Keeping the board surface dry prevents quality defects in subsequent processes. Tin-plated sheets are extremely sensitive to surface oxidation; even slight oxidation can seriously affect their corrosion resistance, solderability, and appearance. Therefore, the drying process of the tin plating line must simultaneously meet the dual requirements of drying and effective oxidation prevention.

[0003] The existing technology has the following drawbacks: (1) "Edge effect" and "black edge" defects: Traditional air knives have a weak airflow effect on the edge of the strip steel, resulting in residual moisture at the edge. This residual moisture causes edge oxidation (i.e. "black edge") in subsequent high-temperature sections or storage, which is a common and difficult-to-eliminate defect of tin-plated steel, affecting product quality.

[0004] (2) Incomplete drying and surface spot defects: Relying solely on air purging can easily cause secondary pollution if the pressure is not properly controlled; and on high-speed production lines, it is difficult to completely remove moisture in the middle area, and residual water droplets evaporate to form surface spots, affecting the uniformity of the coating.

[0005] (3) Risk of secondary oxidation during drying process: If the air contains oxygen and the temperature is high during the drying process, the high temperature and humidity environment can easily cause the tin layer to oxidize and change color, reducing the corrosion resistance and solderability of the tin-plated plate.

[0006] (4) High energy consumption and poor adaptability: To make up for the above deficiencies, the "extensive" mode of large air volume and high air pressure is usually adopted, which has huge energy consumption and noise, and cannot adapt to the deviation of the strip or changes in width.

[0007] Therefore, there is an urgent need in this field for an integrated technical solution that can work organically and synergistically to systematically solve the problems of drying and oxidation of tinplate from three levels: physical removal, thermal evaporation, and chemical protection. Summary of the Invention

[0008] To address the above problems, this invention provides a multi-stage gradient drying and anti-oxidation treatment method and system for a continuous tin-plating thin steel sheet production line.

[0009] To achieve the above objectives, the present invention provides a multi-stage gradient drying and anti-oxidation treatment method for a continuous tin-plating thin steel sheet production line, comprising the following steps sequentially along the strip's running direction: S1. Automatic edge tracking and blowing: The sensor is used to dynamically detect the position of the strip edge, and the air knife nozzle is driven by the servo control system to follow the strip edge and perform fixed-point high-pressure blowing. S2. Overall Surface Purging: High-pressure gas-liquid separation is performed on the full width of the front and back surfaces of the strip steel after S1 treatment using an overall air knife. S3. Steam drying and anti-oxidation: A mixture of high-temperature air and steam is sprayed onto the surface of the strip through a steam duct to achieve final drying and form an anti-oxidation protective layer.

[0010] Furthermore, a multi-stage gradient drying and anti-oxidation treatment method for a continuous tin-plating thin steel sheet production line involves the following steps performed sequentially along the strip's running direction: S1 Edge Pre-drying: The edge position of the strip is detected in real time by the edge position sensor, and the servo mechanism is driven to move the air knife nozzle laterally so that the nozzle is always aimed at the edge of the strip within 5-20mm for fixed-point blowing. The wind speed is set to 25-35m / s, and high-pressure hot air is used to remove the moisture accumulated on the edge. S2 Full-surface high-pressure purging: Using two sets of slit-type integral air knives distributed at the top and bottom, compressed air is sprayed to fully cover the front and back surfaces of the strip steel and remove most of the free water film. S3 High-Temperature Shielding and Drying: A mixture of high-temperature air and steam is sprayed onto the strip surface. Under the high-temperature airflow, the residual adsorbed water evaporates and a gas protective layer is formed on the strip surface to isolate oxygen and prevent the tin layer from oxidizing.

[0011] Optionally, in step S1, the dynamic tracking error of the strip position is controlled within ±0.5mm to adapt to a production speed of 450m / min, and the lateral alignment deviation between the nozzle and the edge of the strip is controlled within ±1mm.

[0012] Optionally, in step S1, the purging gas is compressed air preheated to 10-40°C.

[0013] Optionally, in step S3, the steam duct is V-shaped, and the mixed gas is diffused and sprayed in a fan shape.

[0014] Optionally, the temperature of the mixed gas is 80-120°C, and the surface of the strip is heated to 50-80°C.

[0015] A system for implementing a multi-stage gradient drying and anti-oxidation treatment method in a continuous tin-plating thin steel sheet production line includes a frame, an automatic edge tracking air knife unit, an overall pressurized air knife unit, a steam air knife drying unit, and a central control system. The automatic edge tracking air knife unit is located at the inlet side of the frame and includes a laterally movable edge air knife body and a servo actuator for driving its displacement. The overall pressurized air knife unit is located downstream of the automatic edge tracking air knife unit and includes an overall air knife beam spanning the width of the strip. The steam air knife drying unit is located downstream of the overall pressurized air knife unit and includes a steam generator and a steam nozzle connected thereto. The central control system is used to coordinate and control the operating parameters of the three units, including synchronously adjusting the edge air knife tracking according to the strip width and position, adjusting the overall air knife pressure and the high-temperature unit temperature in conjunction with the production line speed, and controlling the steam flow and temperature in the high-temperature unit.

[0016] Optionally, the edge automatic tracking air knife unit also includes a displacement sensor and a width measuring instrument for detecting the edge position of the strip. Both the sensor and the width measuring instrument are connected to the PLC control system. The PLC control system outputs signals to control the servo actuator. The edge air knife is driven by a dual-axis servo motor with a positioning accuracy of ±0.5mm. The nozzle height from the strip surface is adjustable from 10 to 30mm.

[0017] Optionally, the nozzle of the steam air knife drying unit is provided with a gas guide plate to guide the steam flow into an oblique airflow at an angle of 15°-45° with the running direction of the strip. The nozzle is designed as a fan-shaped diffuser and has a built-in steam exchanger to heat the air to 80-120°C through saturated steam.

[0018] Optionally, the blade lip gap of the integral pressurized air knife unit is adjustable, with an adjustment range of 0.5mm-2.0mm, a blade lip opening of 0.8-1.2mm, and an adjustable angle range of 15°-45°. It adopts a long strip-shaped slit nozzle with a length covering the maximum width of the strip steel + 50mm. The air source is hot air compressed by a high-pressure blower, with a temperature of 20-60℃ and a pressure of 0.6MPa.

[0019] The beneficial effects of this invention are as follows: 1. The present invention has excellent drying effect: it adopts a three-stage progressive treatment of "edge tracking + overall blowing + high temperature drying", which completely solves the defects of "black edge" and "water spot" on the surface, and the product qualification rate is increased to more than 99.5%.

[0020] 2. The invention has strong anti-oxidation ability: The high-temperature air knife not only dries moisture at high temperature, but also uses the reducing atmosphere of steam to isolate oxygen and effectively prevents Sn from oxidizing at high temperature by temperature control, thus maintaining the brightness of the coating.

[0021] 3. The invention has a high degree of intelligence: the edge air knife has an automatic centering function, which can adapt to strip deviation and width changes without manual intervention.

[0022] 4. This invention is energy-saving and environmentally friendly: By independently controlling the air pressure and flow rate in different zones, the waste of large air volume by "one-size-fits-all" is avoided. The air volume and temperature can be automatically adjusted according to the speed of the production line, and the overall energy consumption is reduced by about 15-20%. Attached Figure Description

[0023] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0024] Figure 1 This is a schematic diagram of the overall system structure of the present invention.

[0025] Figure 2 This is a schematic diagram of the edge automatic tracking air knife unit structure.

[0026] Figure 3 This is a schematic diagram of the overall pressurized air knife unit structure.

[0027] Figure 4 This is a schematic diagram of the steam air knife drying unit.

[0028] Explanation of reference numerals in the attached figures 1. Frame; 2. Automatic tracking air knife unit; 21. Side air knife; 22. Fork-shaped position detection sensor; 3. Overall pressurized air knife unit; 31. Slit-type air knife; 32. High-pressure ventilation duct; 33. Vertical high-pressure blower; 4. Steam air knife drying unit; 41. High-temperature steam nozzle; 5. Strip steel. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0030] Example

[0031] Example 1

[0032] Reference Figure 1-4 A drying system for a continuous tin-plating thin steel sheet production line of strip steel 5 (width 600-1250mm, thickness 0.15mm, running speed 450m / min) is provided, consisting of an automatic edge tracking air knife unit 2, an overall pressurized air knife unit 3, and a steam air knife drying unit 4 arranged sequentially along the running direction of strip steel 5. The structure and operating parameters of each unit are as follows: 1. Edge Automatic Tracking Air Knife Unit 2 Driven by a dual-axis servo motor, the dynamic tracking and positioning accuracy of the strip 5 edge is ±0.5mm; the nozzle height from the strip 5 surface is adjustable, with an adjustment range of 20mm; the air source is heated compressed air at a temperature of 30℃ and a pressure of 0.4MPa; during operation, the PLC control system receives the width measuring instrument signal in real time and automatically adjusts the lateral position of the air knife according to the width and edge position of the strip 5, ensuring that the nozzle is always aimed at the strip edge within 10mm for fixed-point blowing, with a blowing speed of 30m / s, accurately removing the moisture accumulated on both sides of the strip 5 edge; II. Overall pressurized air knife unit 3 It adopts a long strip-shaped slit nozzle, with a length covering the maximum width of the strip steel + 50mm, to achieve full-width, no-dead-angle blowing; the blade lip opening is 1.0mm, and the blowing angle is adjustable at 30°; the air source is hot air compressed by a high-pressure blower, with a temperature of 40℃ and a pressure of 0.6MPa; through two sets of integral air knives arranged symmetrically above and below, high-pressure gas-liquid separation is carried out simultaneously on both sides of the strip steel, removing most of the free water film on the strip steel surface; III. Steam air knife drying unit 4 The built-in steam exchanger heats the air to 80-120℃ using saturated steam, forming a mixture of high-temperature air and steam. The nozzle adopts a fan-shaped diffusion structure, with the spray angle at a 30° angle to the running direction of the strip. After spraying, a continuous and uniform air curtain is formed on the surface of the strip, achieving full-width coverage drying and protection.

[0033] A multi-stage gradient drying and anti-oxidation treatment method for a continuous tin-plating thin steel sheet production line, wherein after the strip steel 5 exits the cleaning tank, it enters the three-stage processing unit sequentially at a speed of 450 m / min, and the specific steps are as follows: S1. Automatic edge tracking and purging: A fork-shaped position detection sensor 22 is used to detect the edge position of strip 5 in real time, and the dynamic tracking error of strip 5 is controlled within ±0.5mm. The servo control system drives the edge air knife 21 nozzle to follow the movement and align with the two sides of strip 5 for fixed-point high-pressure blowing. The alignment deviation between the nozzle and the edge of strip 5 is controlled within ±1mm, and the nozzle is aligned with the edge of strip 5 for fixed-point blowing within a range of 5-20mm. The blowing gas is 30℃ preheated compressed air with a pressure of 0.4MPa and a wind speed of 30m / s. The nozzle is 20mm above the surface of strip 5, which accurately removes the moisture accumulated on both sides of strip 5. S2. High-pressure purging of the entire surface: Two sets of long, narrow, integral air knives 31 are used, with nozzle length covering the maximum width of the strip steel 5 + 50mm, blade lip opening of 1.0mm, and blowing angle of 30°. A vertical high-pressure blower 33 sprays air source through high-pressure ventilation pipe 32. The air source is 40℃ high-pressure hot air at a pressure of 0.6MPa. High-pressure gas-liquid separation is carried out simultaneously on the full width of the front and back of the strip steel 5, breaking and blowing away the water film in the main area, and completing the physical removal of most of the free water. S3. Steam drying to prevent oxidation: A V-shaped high-temperature steam nozzle 41 is adopted, with a fan-shaped diffusion structure. The spray angle is 30° with the running direction of the strip steel 5. A mixture of 100°C high-temperature air and steam is sprayed to instantly evaporate the trace amount of adsorbed water on the surface of the strip steel 5, raising the surface temperature of the strip steel 5 to about 120°C. The mixed gas forms an air curtain protective layer on the surface of the strip steel 5, which isolates oxygen and prevents the tin layer from oxidizing, keeping the strip steel 5 dry, bright and free of oxidation.

[0034] Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A method for multi-stage gradient drying and anti-oxidation treatment in a continuous tin-plating thin steel sheet production line, characterized in that: The following steps are performed sequentially along the running direction of the strip (5): S1. Automatic edge tracking and blowing: The sensor is used to dynamically detect the edge of the strip (5), and the air knife nozzle is driven by the servo control system to follow the edge of the strip (5) and perform fixed-point high-pressure blowing. S2, Overall Surface Purging: High-pressure gas-liquid separation is performed on the full width and back surfaces of the strip steel (5) after S1 treatment using an overall air knife; S3. Steam drying and anti-oxidation: High-temperature air and steam mixture is sprayed onto the surface of the strip steel (5) through steam duct to perform final drying and form an anti-oxidation protective layer.

2. The multi-stage gradient drying and anti-oxidation treatment method for a continuous tin-plating thin steel sheet production line according to claim 1, characterized in that: In step S1, the dynamic tracking error of the strip (5) position is controlled within ±0.5mm, adapting to a production speed of 450m / min, and the lateral alignment deviation between the nozzle and the edge of the strip is controlled within ±1mm.

3. The multi-stage gradient drying and anti-oxidation treatment method for a continuous tin-plating thin steel sheet production line according to claim 1, characterized in that: In step S1, the purging gas is compressed air preheated to 10-40°C.

4. The multi-stage gradient drying and anti-oxidation treatment method for a continuous tin-plating thin steel sheet production line according to claim 1, characterized in that: In step S3, the steam duct is V-shaped, and the mixed gas is diffused and sprayed in a fan shape.

5. The multi-stage gradient drying and anti-oxidation treatment method for a continuous tin-plating thin steel sheet production line according to claim 4, characterized in that: The temperature of the mixed gas is 80-120℃, and the surface of the strip steel is heated to 50-80℃.

6. A system for implementing the multi-stage gradient drying and anti-oxidation treatment method for a continuous tin-plating thin steel sheet production line as described in any one of claims 1-5, characterized in that: The system includes a frame (1), an automatic edge tracking air knife unit (2), an overall pressurized air knife unit (3), a steam air knife drying unit (4), and a central control system. The automatic edge tracking air knife unit (2) is located at the inlet side of the frame (1) and includes a side air knife (21) body that can move laterally and a servo actuator that drives its displacement. The overall pressurized air knife unit (3) is located downstream of the automatic edge tracking air knife unit and includes an overall air knife beam that spans the width of the strip. The steam air knife drying unit (4) is located downstream of the overall pressurized air knife unit and includes a steam generator and a steam nozzle connected thereto. The central control system is used to coordinate and control the operating parameters of the three units, including synchronously adjusting the tracking of the side air knife according to the width and position of the strip (5), adjusting the overall air knife pressure and the temperature of the high-temperature unit in conjunction with the production line speed, and controlling the flow rate and temperature of the steam in the high-temperature unit.

7. The system of the multi-stage gradient drying and anti-oxidation treatment method for the continuous electroplating tin-plated thin steel sheet production line according to claim 6, characterized in that: The edge automatic tracking air knife unit (2) also includes a fork-shaped position detection sensor (22) and a width measuring instrument for detecting the edge position of the strip. The fork-shaped position detection sensor (22) and the width measuring instrument are both connected to the PLC control system. The PLC control system outputs signals to control the servo actuator. The edge air knife (21) is driven by a dual-axis servo motor with a positioning accuracy of ±0.5mm. The nozzle distance from the surface of the strip (5) is adjustable in the range of 10-30mm.

8. The system of the multi-stage gradient drying and anti-oxidation treatment method for the continuous electroplating tin-plated thin steel sheet production line according to claim 6, characterized in that: The steam air knife drying unit (4) is equipped with a gas guide plate at the nozzle to guide the steam flow into an oblique airflow at an angle of 15°-45° with the running direction of the strip. The nozzle is designed as a fan-shaped diffuser and has a built-in steam exchanger to heat the air to 80-120°C through saturated steam.

9. The system of the multi-stage gradient drying and anti-oxidation treatment method for the continuous electroplating tin-plated thin steel sheet production line according to claim 6, characterized in that: The blade lip gap of the integral pressurized air knife unit (3) is adjustable, with an adjustment range of 0.5mm-2.0mm, a blade lip opening of 0.8-1.2mm, and an angle adjustable range of 15°-45°. It adopts a long strip-shaped slit nozzle with a length covering the maximum width of the strip steel + 50mm. The air source is hot air compressed by a high-pressure blower, with a temperature of 20-60℃ and a pressure of 0.6MPa.

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