A production method for ultra-deep drawn self-lubricating hot-dip galvanized household appliance sheet

Abstract

The present invention relates to the technical field of hot-dip galvanized sheets, and specifically to a method for producing ultra-deep drawn self-lubricating hot-dip galvanized household appliance sheets. The method includes: 1) rolling mill control; 2) linked control of the tension in the heating section of the furnace and the deviation detection value; 3) roughness control of the furnace rollers in the galvanizing annealing furnace; 4) convexity control of the furnace rollers; and 5) control of the tension rollers. The method achieves the goal of reducing the probability of deviation and thermal wrinkling in the furnace of ultra-deep drawn self-lubricating hot-dip galvanized household appliance sheets without increasing equipment investment, reducing slippage, scratching defects, and downtime in finished products, ensuring high-quality and efficient production of ultra-deep drawn self-lubricating hot-dip galvanized household appliance sheets, and ensuring stable unit operation and product quality that meets requirements.

Description

Technical Field

[0001] The invention relates to the technical field of hot-dip galvanized sheets, in particular to a production method of an ultra-deep drawn self-lubricating hot-dip galvanized household appliance sheet. Background Art

[0002] The modified Sendzimir hot-dip galvanizing unit and the US Steel Union unit are the two main methods for producing hot-dip galvanized sheets. The US Steel Union unit has no open flame heating section in the furnace area, and the length of the radiation tube section is much longer than that of the modified Sendzimir hot-dip galvanizing unit. In addition, the heating uniformity of the US Steel Union unit is better than that of the modified Sendzimir hot-dip galvanizing unit. Therefore, for the production of ultra-deep drawn self-lubricating hot-dip galvanized household appliance sheets with low yield strength and high requirements for surface quality and self-lubrication, the newly built steel mills of major steel companies currently generally use the US Steel Union unit to produce hot-dip galvanized ultra-deep drawn self-lubricating galvanized household appliance sheets.

[0003] However, the cost of building a new US Steel hot-dip galvanizing unit is relatively high. How to use the existing improved Sendzimir unit to stably and high-quality produce ultra-deep-drawn self-lubricating fingerprint-resistant hot-dip galvanized sheet has become a common problem. The specific reasons are as follows: 1. Since the continuous annealing furnace of the improved Sendzimir hot-dip galvanizing unit adopts direct-fired heating and is at a relatively high height, when the strip steel runs in the continuous annealing furnace, it is affected by variables such as specification changes, speed changes, and temperature changes during annealing scheduling. In the early production, there is a greater risk of strip deviation, breakage, and thermal wrinkling defects, which will cause strip breakage accidents and produce quality scrap, seriously affecting the yield rate of such products and the progress of contract execution. 2. The improved Sendzimir hot-dip galvanizing unit for producing ultra-deep drawn hot-dip galvanized household appliance plates has always had problems with a high surface friction coefficient and poor lubricity during processing, which easily causes stamping cracks and blackening of the contact surface during stamping or bending. By adjusting the composition of the anti-fingerprint liquid and adding solid lubricants, the surface friction coefficient is significantly reduced and the lubricity during processing is significantly improved. However, due to the reduction in the surface friction coefficient of the steel plate, the friction between the strip steel and the main drive roller system after the passivation section is sharply reduced, resulting in shutdowns and scratches on the steel plate surface caused by slippage between the steel plate and the roller system. The unit's operating stability is poor and the surface quality of the steel plate does not meet the requirements.

[0004] The Chinese patent document with application number CN202110024594.X discloses "A strip correction device and method in a continuous annealing furnace", the Chinese patent document with application number CN202010685311.1 discloses "An automatic correction control method for a continuous annealing heating furnace for cold-rolled strip steel", and the Chinese patent document with application number CN201310034896.0 discloses "A lubricating coating for galvanized steel sheets, self-lubricating galvanized steel sheets and their production method", all of which cannot achieve the stable production of ultra-deep drawn self-lubricating galvanized household appliance sheets and solve the above technical problems. Summary of the Invention

[0005] To overcome the shortcomings of the existing technology, the present invention provides a method for producing ultra-deep-drawn, self-lubricating, hot-dip galvanized household appliance sheets. This method reduces the probability of in-furnace deviation and thermal wrinkling of ultra-deep-drawn, self-lubricating, hot-dip galvanized household appliance sheets, reduces slippage, scratches, and downtime in finished products, and ensures high-quality and efficient production of ultra-deep-drawn, self-lubricating, hot-dip galvanized household appliance sheets, stable operation of the unit, and compliance with product quality requirements, without increasing equipment investment.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for producing ultra-deep drawn self-lubricating hot-dip galvanized household appliance plates, the production method being specifically as follows:

[0008] 1) Rolling mill rolling control

[0009] The tension deviation of each frame is controlled within ±10KN;

[0010] II All production materials use micro-edge wave control uniformly;

[0011] Only slight waves are allowed within 150mm from both sides of the strip width, with a wave height of ≤4mm and a wave length of ≥300mm;

[0012] III The bending closed loop of the five working rolls is controlled within 40%.

[0013] 2) Linkage control of the tension in the heating section of the furnace and the deviation detection value

[0014] The tension values ​​of products of various steel grades and specifications in the heating section are assigned according to two categories: Normal and Special. If the strip deviation detection value is within the set range, the tension value in Normal is implemented; otherwise, the tension value in Special is implemented.

[0015] 3) Roughness control of galvanized annealing furnace rollers

[0016] The working area of ​​the furnace roller is divided into preheating section, heating section, soaking section, slow cooling section and fast cooling section. The heating section is divided into the first heating section, the second heating section and the third heating section, and the roughness of each section is controlled within the set range.

[0017] 4) Furnace roller crown control

[0018] I. Control the initial crown of the furnace rollers in different working areas;

[0019] II Control the fan current value of thermal crown in different sections according to the width and thickness of the strip;

[0020] As the thickness of the strip increases, the current value of the thermal crown fan in each section is gradually increased; under the condition of the same thickness, as the width of the strip increases, the current value of the thermal crown fan in each section is gradually reduced.

[0021] 5) Control tension roller

[0022] The surface of the tension roller is treated with tungsten carbide coating, and the roller surface roughness Ra is not less than 4.2um;

[0023] II. The pressure roller is pressed down 3 to 6 seconds before the unit slows down due to a break in the web and rotates accordingly until it is raised 3 to 6 seconds after the unit resumes its speed after rethreading and recovers to the stable process speed.

[0024] III. Control the tension coefficient according to the width and thickness of the strip;

[0025] As the thickness of the strip increases, the tension control coefficient is gradually increased; under the condition of the same thickness, as the width of the strip increases, the tension control coefficient is gradually reduced.

[0026] Furthermore, in the above 2), Normal is a normal state, Special is a special state; and the strip deviation detection value is set in the range of -3mm to +3mm.

[0027] Furthermore, in the above 3), the roughness of the furnace rollers in the preheating section is controlled to be 4-6, the roughness of the furnace rollers in the first heating section is controlled to be 4-6, the roughness of the furnace rollers in the second heating section is controlled to be 3-5, the roughness of the furnace rollers in the third heating section is controlled to be 3-5, the roughness of the furnace rollers in the soaking section is controlled to be 2-4, the roughness of the furnace rollers in the slow cooling section is controlled to be 2-4, and the roughness of the furnace rollers in the fast cooling section is controlled to be 3-5.

[0028] Furthermore, in said 4)I, the initial convexity value of the furnace roller in the preheating section is controlled to be not less than 0.6 mm, the initial convexity value of the furnace roller in the heating section is controlled to be not less than 0.4 mm, the initial convexity value of the furnace roller in the soaking section is controlled to be not less than 0.2 mm, the initial convexity value of the furnace roller in the slow cooling section is controlled to be not less than 0.2 mm, and the initial convexity value of the furnace roller in the fast cooling section is controlled to be not less than 0.4 mm.

[0029] Furthermore, in said 5) II, the pressing roller is pressed down in advance 5 seconds before the unit breaks the web and slows down, and rotates accordingly, and is not lifted up again until the unit recovers to the stable process speed after re-threading and speeding up.

[0030] Compared with the existing method, the present invention has the following beneficial effects:

[0031] Compared with the existing technology, the present invention optimizes the raw material quality requirements, optimizes the initial roller shape design of the furnace roller, optimizes the roller surface roughness design, optimizes the furnace roller thermal convexity control method, optimizes the tension adjustment control scheme in the furnace, optimizes the roller surface technical indicators and roller form after the passivation section, improves the transmission roller system and tension system after the passivation section, and conducts in-depth research and innovation without increasing equipment investment. The invention reduces the probability of deviation and thermal wrinkling of ultra-deep drawn self-lubricating hot-dip galvanized household appliance plates in the furnace, reduces the slippage and scratch defects and shutdown of the finished products, and realizes high-quality and efficient production of ultra-deep drawn self-lubricating hot-dip galvanized household appliance plates, ensuring stable operation of the unit and compliance with product quality requirements. DETAILED DESCRIPTION

[0032] The present invention discloses a method for producing ultra-deep-drawn, self-lubricating, hot-dip galvanized household appliance panels. Those skilled in the art may refer to the contents herein and appropriately modify the process parameters to achieve the desired result. It is particularly important to note that all similar substitutions and modifications obvious to those skilled in the art are considered encompassed by the present invention. The methods and applications of the present invention have been described through preferred embodiments. It is apparent that those skilled in the art can modify or appropriately alter and combine the methods and applications described herein to implement and apply the technology of the present invention without departing from the content, spirit, and scope of the present invention.

[0033] Example:

[0034] A method for producing ultra-deep drawn self-lubricating hot-dip galvanized household appliance plates is as follows:

[0035] 1. Control the quality of the raw material plate shape of ultra-deep drawn self-lubricating hot-dip galvanized household appliance plate products:

[0036] 1) Rolling process control of rolling mill

[0037] I. Tension deviation between stands: During normal rolling, the tension deviation of each stand must be controlled within ±10KN;

[0038] II All production materials are uniformly controlled with micro-edge wave (raised on both sides, concave in the middle, and the vertical coordinate of the edge is 0.22);

[0039] III The bending closed loop of the five working rolls is controlled within 40%.

[0040] 2) Inspection criteria for plate shape after rolling:

[0041] The requirements for the I value of the flatness gauge after rolling are shown in Table 1.

[0042] Table 1 Requirements for the average value of I for each thickness

[0043] Thickness level Mean I value <0.60mm material 2.5 0.60-1.00mm material 3.0 >1.00mm material 3.5

[0044] II. Inspection and control standards for the physical plate shape of finished products after rolling, see Table 2.

[0045] Table 2 Inspection standards for physical plate shape after rolling

[0046]

[0047] 2. Linkage control of the tension in the heating section of the furnace and the deviation detection value:

[0048] In the heating section, tension values ​​for each steel grade and specification are assigned according to normal and special categories, as shown in Table 3. The normal and special tension values ​​in Table 3 are applied to the different ranges of deviation detection values ​​of the correction device. The specific rule is that when the actual deviation detection value is within the range of -3mm to +3mm, tension control implements the tension value in the "Normal" column in Table 3. When the strip deviation detection value exceeds the range of -3mm to +3mm, tension control implements the tension value in the "Special" column in Table 3.

[0049] Table 3 Tension table of heating section after optimization

[0050]

[0051]

[0052] 3. Roughness control of galvanized annealing furnace rollers

[0053] Refine the roughness standards for furnace rollers in each section of the furnace area. Clarify the inspection standards for new rollers when they are put into production, and refine the inspection methods and standards for furnace roller roughness during each furnace start-up and maintenance. See Table 4 for details.

[0054] Table 4 Furnace roller roughness control scheme

[0055]

[0056] 4. Control of furnace roller crown

[0057] 1) Design of initial crown of furnace roller

[0058] The initial crown of the furnace rolls in different working areas should be reasonably designed. For furnace rolls that tend to develop positive crown during operation, the initial crown should be designed as a small positive crown; for furnace rolls that tend to develop negative crown during operation, the initial crown should be designed as a large positive crown. See Table 5 for details.

[0059] Table 5 Control scheme for initial crown of furnace roller

[0060]

[0061] 2) Furnace roller thermal crown control scheme

[0062] The control scheme of the furnace roller thermal crown fan is optimized. The optimized scheme adopts different amplitude ranges of the temperature difference between the furnace roller and the strip in different sections, combined with the cross-sectional area of ​​the material (heat exchange intensity), and optimizes and solidifies the speed and current value of the thermal crown fan in different sections according to the material thickness and width. See Table 6 for details.

[0063] Table 6 Furnace roller thermal crown fan control scheme

[0064]

[0065] 5. Reduce scratches on high-lubricity fingerprint-resistant plates

[0066] In order to avoid slippage between the roller surface and the strip and ensure stable operation of the unit, the following measures are taken:

[0067] 1) Improve the surface material of the main drive roller system (tension roller) after the passivation section, all use tungsten carbide coating, and the roller surface roughness Ra is required to be no less than 4.2um.

[0068] 2) A belt-driven pressure roller is added to the steering roller of the inspection table, and the control program of the pressure roller intervention is optimized. The pressure roller is pressed down 5 seconds before the unit breaks and slows down, and it rotates until the unit recovers to the stable process speed after re-threading and speeding up, and then lifted up 5 seconds later. This increases the friction between the strip and the roller surface during the acceleration and deceleration period, and keeps the strip and the roller surface at the same speed.

[0069] 3) Optimize the tension coefficient of the INSPECTION segment to form a fixed linkage tension adjustment mechanism to avoid the roller slipping problem caused by excessive tension difference and uneven distribution. The specific optimization plan is shown in Table 7.

[0070] Table 7 Optimized tension coefficient table

[0071]

[0072]

[0073] The present invention has been applied in actual production. Before implementation, the comprehensive scrap rate of defects caused by deviation, belt breakage, heat wrinkles and scratches was 0.79%, while after implementation, the comprehensive scrap rate was 0.34%.

[0074] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A method for producing ultra-deep drawn self-lubricating hot-dip galvanized household appliance sheets, characterized in that: The production method is specifically as follows: 1) Rolling mill rolling control The tension deviation of each frame is controlled within ±10KN; II All production materials use micro-edge wave control uniformly; Only slight waves are allowed within 150mm from both sides of the strip width, with a wave height of ≤4mm and a wave length of ≥300mm; III. The closed loop of the five working rolls is controlled within 40%; 2) Linkage control of the tension in the heating section of the furnace and the deviation detection value The tension values ​​of products of various steel grades and specifications in the heating section are assigned according to two categories: Normal and Special. If the strip deviation detection value is within the set range, the tension value in Normal is implemented; otherwise, the tension value in Special is implemented. 3) Roughness control of galvanized annealing furnace rollers The working area of ​​the furnace roller is divided into preheating section, heating section, soaking section, slow cooling section and fast cooling section. The heating section is divided into the first heating section, the second heating section and the third heating section. The roughness of each section is controlled within the set range. 4) Furnace roller crown control I. Control the initial crown of the furnace rollers in different working areas; II Control the fan current value of thermal crown in different sections according to the width and thickness of the strip; As the thickness of the strip increases, the current value of the thermal crown fan in each section is gradually increased; under the condition of the same thickness, as the width of the strip increases, the current value of the thermal crown fan in each section is gradually reduced; 5) Control tension roller The surface of the tension roller is treated with tungsten carbide coating, and the roller surface roughness Ra is not less than 4.2um; II. The pressure roller is pressed down 3 to 6 seconds before the unit slows down due to a break in the web and rotates accordingly until it is raised 3 to 6 seconds after the unit resumes its speed after rethreading and recovers to the stable process speed. III. Control the tension coefficient according to the width and thickness of the strip; As the thickness of the strip increases, the tension control coefficient is gradually increased; under the condition of the same thickness, as the width of the strip increases, the tension control coefficient is gradually reduced.

2. The method for producing ultra-deep drawn self-lubricating hot-dip galvanized household appliance sheet according to claim 1, characterized in that: In the above 2), Normal refers to the normal state, and Special refers to the special state; the strip deviation detection value is set in the range of -3mm to +3mm.

3. The method for producing ultra-deep drawn self-lubricating hot-dip galvanized household appliance sheet according to claim 1, characterized in that: In the above 3), the roughness of the furnace roller in the preheating section is controlled to be 4-6 μm, the roughness of the furnace roller in the first heating section is controlled to be 4-6 μm, the roughness of the furnace roller in the second heating section is controlled to be 3-5 μm, the roughness of the furnace roller in the third heating section is controlled to be 3-5 μm, the roughness of the furnace roller in the soaking section is controlled to be 2-4 μm, the roughness of the furnace roller in the slow cooling section is controlled to be 2-4 μm, and the roughness of the furnace roller in the fast cooling section is controlled to be 3-5 μm.

4. The method for producing ultra-deep drawn self-lubricating hot-dip galvanized household appliance sheet according to claim 1, characterized in that: In the above 4)I, the initial convexity value of the furnace roller in the preheating section is controlled to be not less than 0.6mm, the initial convexity value of the furnace roller in the heating section is controlled to be not less than 0.4mm, the initial convexity value of the furnace roller in the soaking section is controlled to be not less than 0.2mm, the initial convexity value of the furnace roller in the slow cooling section is controlled to be not less than 0.2mm, and the initial convexity value of the furnace roller in the fast cooling section is controlled to be not less than 0.4mm.

5. The method for producing ultra-deep drawn self-lubricating hot-dip galvanized household appliance sheet according to claim 1, characterized in that: In the above 5) II, the pressing roller is pressed down in advance 5 seconds before the unit slows down due to a break in the roll and rotates accordingly, and is not lifted up again until the unit recovers to a stable process speed after re-threading and speeding up.

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