Method for controlling roll mark defects on surface of pickling plate

Abstract

The invention provides a method for controlling roll mark defects on the surface of a pickling plate, which comprises the following steps: a prevention step: controlling a front pinch roll, a wringing roll and a tension roll of a straightening machine of a pickling line to operate within a preset range; and a correction step: determining and correcting the defects of the pickling line according to the defects of the pickling plate produced by the pickling line. According to the control method for the surface roll mark defect of the pickled plate provided by the embodiment of the invention, the prevention step and the correction step are comprehensively carried out for maintenance, so that the yield of the pickled plate roll mark defect belt is reduced to be less than 0.05% from the previous 0.20%, the profitability of the pickled product is enhanced, and the company image is greatly improved.

Description

Technical Field

[0001] The present application relates to the field of metallurgical plate production, and in particular to a method for controlling roller mark defects on the surface of pickling plates. Background Art

[0002] Hot-rolled pickled steel is made from high-quality hot-rolled thin steel. After being pickled to remove the oxide layer, trimmed, and finished, the resulting product's surface quality and performance requirements (primarily cold bend forming or stamping performance) lie between those of hot-rolled and cold-rolled steel. It is an ideal alternative to some hot-rolled and cold-rolled steel products. Compared to hot-rolled steel, pickled steel offers the following advantages: 1) superior surface quality. Since hot-rolled pickled steel removes surface scale, the surface quality of the steel is improved, making it easier to weld, oil, and paint. 2) high dimensional accuracy. After leveling or straightening, the steel's shape can be modified to a certain degree, reducing unevenness. 3) improved surface finish enhances the appearance. 4) reduced environmental pollution caused by dispersed pickling processes. Compared to cold-rolled steel, pickled steel offers the advantage of effectively reducing procurement costs while ensuring surface quality requirements.

[0003] The roller mark defect of pickling plate is a common surface quality defect of pickling line. It appears as dots, lines or irregular ovals, and has different degrees of hand feel, which seriously affects the surface quality of pickling plate and the products of subsequent processes. On the other hand, once the roller mark defect occurs, it can only be downgraded or removed, resulting in huge quality losses. Therefore, it is necessary to control the roller mark defect of pickling plate. Summary of the Invention

[0004] The embodiment of the present application provides a method for controlling roller mark defects on the surface of a pickling plate, which is suitable for a pickling line, can reduce roller mark defects on the surface of the pickling plate, and meet the high surface quality requirements of the pickling plate.

[0005] The method for controlling roller mark defects on the surface of the pickling plate provided in the embodiment of the present application includes: a prevention step, including controlling the operation of the front pinch roller, squeeze roller and tension roller of the straightener of the pickling line within a preset range; a correction step, including determining the defects of the pickling line and correcting them based on the defects that have appeared in the pickling plates produced by the pickling line.

[0006] According to the implementation method of the present application, the prevention steps include: removing foreign matter adhered to the front pinch roller of the straightening machine, the foreign matter including iron oxide scale; analyzing the reasons why the front pinch roller of the straightening machine is prone to sticking foreign matter, and solving the problem of foreign matter sticking to the front pinch roller of the straightening machine according to the reasons.

[0007] According to the implementation mode of the present application, the preventive step also includes: inspecting and cleaning the upper and lower roller surfaces of the front pinch rollers of the straightening machine to remove foreign matter every shift.

[0008] According to an embodiment of the present application, the preventive step further includes: adjusting the front pinch rollers of the straightening machine so that the roller gap accuracy of the front pinch rollers of the straightening machine is controlled within 0.20 mm in the no-load, press-down mode.

[0009] According to the implementation of the present application, the preventive step also includes: adjusting the front pinch roller of the straightening machine so that after the front pinch roller of the straightening machine is pressed down, the roller gap deviation between the operating side and the transmission side does not exceed 0.05 mm.

[0010] According to the embodiment of the present application, the preventive step further includes: controlling the acceleration and deceleration of the squeeze roller in the process section to ±0.17m / s 2 -±0.1m / s 2 , to reduce the impact of instantaneous acceleration and deceleration on the strip surface; for special varieties, step-by-step acceleration and deceleration are implemented during the acceleration and deceleration process; the hardness of the rubber layer on the roller surface of the squeeze roller is controlled within the range of 69±2.5HRC.

[0011] According to the implementation mode of the present application, the step-by-step acceleration and deceleration includes: when the process section needs to be accelerated from the threading speed of 40-60m / min to the maximum speed of 150-180m / min, a step-by-step acceleration of the speed is performed every 20-40m / min; when the process section is decelerated from the maximum speed to the tail-swinging speed of 40-90m / min, a step-by-step deceleration of the speed is performed every 20-40m / min.

[0012] According to the implementation method of the present application, the preventive steps also include: regularly cleaning the tension roller after the disc shear of the pickling line to reduce foreign matter; formulating key quality equipment replacement and inspection requirements, and regularly replacing the tension roller to prevent the tension roller from being worn too much and causing friction roller mark defects.

[0013] According to the implementation method of the present application, the correction step includes: inspecting the surface quality condition of the pickling plate by manual visual inspection or surface quality inspection instrument, and if a periodic pickling plate roller mark defect is detected, measuring the roller mark occurrence cycle, locking the roller mark occurrence position according to the production line roller mark cycle table, and performing cleaning or grinding.

[0014] According to an embodiment of the present application, the correction step further includes: when a squeeze roller mark defect occurs, lowering the acid temperature in the pickling section to 75-80°C to alleviate the erosion of the high-temperature acid on the squeeze roller surface.

[0015] Compared with the prior art, the embodiments of the present application have at least the following beneficial effects:

[0016] The control method for roller mark defects on the surface of pickled plates provided in the embodiment of the present application reduces the output rate of pickled plates with roller mark defects from the previous 0.20% to less than 0.05% by comprehensively performing preventive steps and corrective steps, thereby enhancing the profitability of pickled products and significantly improving the company's image. DETAILED DESCRIPTION

[0017] In order to make the application purpose, technical solution and beneficial technical effects of this application clearer, the application is further described in detail below with reference to the embodiments. It should be understood that the embodiments described in this specification are only for explaining this application and are not intended to limit this application.

[0018] For simplicity, this application only explicitly discloses certain numerical ranges. However, any lower limit may be combined with any upper limit to form an unspecified range; and any lower limit may be combined with other lower limits to form an unspecified range, and similarly, any upper limit may be combined with any other upper limit to form an unspecified range. In addition, although not explicitly stated, each point or individual value between the endpoints of a range is included in the range. Thus, each point or individual value may serve as its own lower limit or upper limit and be combined with any other point or individual value, or with other lower limits or upper limits, to form an unspecified range.

[0019] In the description of this application, it should be noted that, unless otherwise specified, “above”, “below” and “not more than” are inclusive of the number itself, and the “multiple” in “one or more” means two or more than two.

[0020] The above disclosure of the present application is not intended to describe every disclosed embodiment or every implementation in the present application. The following description more specifically illustrates exemplary embodiments. In many places throughout the application, guidance is provided through a series of examples, which can be used in various combinations. In each example, the enumeration is intended only as a representative group and should not be construed as exhaustive.

[0021] Hot-rolled pickled steel, due to its high cost-effectiveness and favorable economic benefits, is finding an increasingly wide range of applications, primarily in low-, medium-, and high-strength stamping steel, automotive structural steel, and other applications. Hot-rolled pickled steel is experiencing rapid growth internationally, particularly in Japan, the United States, South Korea, and several European countries, where its production already accounts for 3% to 4% of total general steel production. Domestically, however, the industry is still in its developmental stages, offering broad application prospects.

[0022] The roller mark defect of pickling plate is a common surface quality defect of pickling line. It appears as dots, lines or irregular ovals, and has different degrees of hand feel, which seriously affects the surface quality of pickling plate and the products of subsequent processes. On the other hand, once the roller mark defect occurs, it can only be downgraded or removed, resulting in huge quality losses. Therefore, it is necessary to control the roller mark defect of pickling plate.

[0023] In view of the above problems, an embodiment of the present application provides a method for controlling roller mark defects on the surface of a pickling plate, which is suitable for a pickling line, can reduce roller mark defects on the surface of a pickling plate, and meet the high surface quality requirements of the pickling plate.

[0024] The method for controlling roller mark defects on the surface of the pickling plate provided in the embodiment of the present application includes: a prevention step, including controlling the operation of the front pinch roller, squeeze roller and tension roller of the straightener of the pickling line within a preset range; a correction step, including determining the defects of the pickling line and correcting them based on the defects that have appeared in the pickling plates produced by the pickling line.

[0025] The solution to roller mark defects on the surface of pickled plates in the present embodiment is as follows: First, prevent the occurrence of roller mark defects in pickled plates in advance. By analyzing and determining the locations and periodic characteristics where roller mark defects are likely to occur, the specific points with a high frequency of roller mark defects are further determined. The causes of roller mark defects at these points are analyzed, and corresponding control measures are formulated to ultimately achieve effective control of roller mark defects on pickled plates. Then, if roller mark defects have already occurred, the pickling line defects are identified and corrected based on the defects that have already occurred on pickled plates produced by the pickling line.

[0026] In the entire production line design of the pickling line, most guide rollers and pinch rollers are rubber rollers, and the steel channels are also inlaid with nylon liners to prevent the pickling plates from making hard contact with the steel channels, resulting in scratches, roller marks and other surface quality defects.

[0027] However, pickling plate roller mark defects will still occur in the three areas of the straightening machine's front pinch roller, squeeze roller and tension roller. In particular, the occurrence rate of roller mark defects of the straightening machine's front pinch roller is relatively high, and the overall output rate of roller mark defects is high. Therefore, it is necessary to invent a method for controlling pickling plate roller mark defects.

[0028] In some embodiments, the preventive steps include: removing foreign matter adhered to the front pinch roller of the straightening machine, including iron oxide scale; analyzing the reasons why foreign matter is easily adhered to the front pinch roller of the straightening machine, and solving the problem of foreign matter adhering to the front pinch roller of the straightening machine according to the reasons.

[0029] In some embodiments, the preventive step further includes: inspecting and cleaning the upper and lower roller surfaces of the front pinch rollers of the straightening machine to remove foreign matter every shift.

[0030] In some embodiments, the preventive step further includes: adjusting the front pinch rollers of the straightening machine so that the roller gap accuracy of the front pinch rollers of the straightening machine is controlled within 0.20 mm in the no-load, press-down mode.

[0031] In some embodiments, the preventive step further includes: adjusting the front pinch roller of the straightening machine so that after the front pinch roller of the straightening machine is pressed down, the roller gap deviation between the operating side and the transmission side does not exceed 0.05 mm.

[0032] The pinch rollers in front of the straightening machine are responsible for establishing the uncoiling tension together with the uncoiler and performing the important functions of uncoiling and threading the tape. Therefore, they are set as smooth rollers whether in the design of push-pull pickling lines or continuous pickling lines.

[0033] During the uncoiling process of the pickled plate, the roller is prone to adhere to foreign matter such as iron oxide scale that falls off the surface of the hot-rolled strip, resulting in pickled plate roller mark defects.

[0034] Further analysis revealed the reason why the pinch rollers at the front of the straightener are prone to sticking to foreign matter such as scale. The pinch rollers at the front of the straightener, along with the uncoiler, create a relatively high unwinding tension. To ensure a good tension buildup, these rollers must bear a significant forward driving force. During the forward pinching and threading process, they are prone to slipping against the strip surface, which can cause foreign matter to stick and cause roller mark defects.

[0035] Furthermore, the main reason why the front pinch rollers of the straightener are prone to slippage is that the roller gap control accuracy is insufficient, which makes it impossible to clamp the strip. This causes the roller surface and the strip to move relative to each other during the strip feeding process, resulting in slippage. To avoid strip slippage, it is necessary to ensure good roller gap control accuracy and regularly measure and adjust the roller gap of the front pinch rollers of the straightener to ensure that the roller gap accuracy of the front pinch rollers of the straightener is controlled within 0.20mm in the no-load, pressure mode.

[0036] Furthermore, in order to prevent the inconsistent accuracy of the roll gaps on both sides, which may cause the roll gaps on both sides to be inconsistent after the front pinch rollers of the straightening machine are pressed down, thereby causing wavy defects in the strip, it is required that the deviation of the roll gaps on the operating side and the transmission side shall not exceed 0.05mm.

[0037] In addition, under the premise of ensuring the control accuracy of the roller gap of the pinch roller in front of the straightening machine, it is still necessary to regularly check and clean the roller surface to further eliminate the pickling plate roller mark defects caused by foreign matter sticking to the pinch roller in front of the straightening machine.

[0038] In some embodiments, the prevention step further includes: controlling the acceleration and deceleration of the squeeze roller in the process section to ±0.167 m / s 2 , to reduce the impact of instantaneous acceleration and deceleration on the strip surface; for special varieties, step-by-step acceleration and deceleration are implemented during the acceleration and deceleration process; the hardness of the rubber layer on the roller surface of the squeeze roller is controlled within the range of 69±2.5HRC.

[0039] During the metal processing process, the squeeze rollers are in close contact with the strip, and changes in their speed directly affect the stress state of the strip. When the squeeze rollers accelerate or decelerate instantly, the friction between the strip and the roller surface will suddenly change due to the rapid change in acceleration. This instantaneous force impact can easily cause scratches, indentations and other defects on the strip surface. The acceleration and deceleration are strictly controlled at ±0.17m / s. 2 -±0.1m / s 2, enabling smooth speed transitions for the squeeze rollers. For example, when the strip is running at a constant speed, slow acceleration changes gradually increase or decrease the friction between the roller surface and the strip, preventing damage to the strip surface caused by sudden force changes. Furthermore, stable speed changes help maintain equipment stability, reducing mechanical vibration and component wear caused by inertial impact, lowering the risk of equipment failure and ensuring production continuity.

[0040] For example, the acceleration and deceleration is 0.17 m / s 2 , 0.167m / s 2 , 0.16m / s 2 , 0.15m / s 2 , 0.14m / s 2 , 0.13m / s 2 , 0.12m / s 2 , 0.11m / s 2 , 0.10m / s 2 、-0.10m / s 2 、-0.11m / s 2 、-0.12m / s 2 、-0.13m / s 2 、-0.14m / s 2 、-0.15m / s 2 、-0.16m / s 2 、-0.167m / s 2 or -0.17m / s 2 .

[0041] Different types of strip steel vary significantly in material, thickness, and performance, and their tolerance to acceleration and deceleration processes varies. Conventional uniform acceleration and deceleration methods are unlikely to meet the quality requirements of special types of strip steel. Stepped acceleration and deceleration provides a more refined control solution for special strip steel by adjusting the acceleration in stages and gradients. For example, high-strength, high-hardness alloy steel strip has weak plastic deformation capacity. If conventional acceleration and deceleration are used, excessive instantaneous force may cause cracks on the strip surface or internal stress concentration. Stepped acceleration and deceleration first uses a small acceleration to allow the strip to adapt to the speed change, and then gradually increases the acceleration to the target value, effectively avoiding sudden stress changes. For ultra-thin precision strip steel, due to its thin thickness and poor rigidity, stepped deceleration can prevent wrinkles and tears caused by sudden speed drops. This differentiated control strategy can accurately adjust the force according to the characteristics of the special strip steel, ensuring the surface quality and integrity of the strip steel.

[0042] The hardness of the rubber coating on the squeeze roller surface directly affects its contact with the strip and the squeeze efficiency. If the hardness of the rubber coating is too low, it can easily lose its flatness due to extrusion deformation during the squeeze process, resulting in surface defects such as roller marks and indentations. Furthermore, a low-hardness rubber coating has poor wear resistance and a short service life. Frequent replacement not only increases costs but also affects production efficiency. Conversely, a rubber coating with excessive hardness makes the roller surface too rigid, generating significant localized pressure when in contact with the strip, potentially scratching the strip surface. Controlling the rubber coating hardness within the range of 69±2.5HRC ensures that the rubber coating has both good elasticity and wear resistance. A rubber coating of appropriate hardness effectively conforms to the strip surface during squeeze operation, ensuring sufficient removal of residual liquid, while also buffering pressure through appropriate elastic deformation to avoid damage to the strip surface. Furthermore, a stable hardness range helps ensure consistent squeeze roller performance, maintains consistent strip surface quality, and improves product qualification rates.

[0043] Exemplarily, the hardness of the gelatinous layer is 71.5 HRC, 71 HRC, 70.5 HRC, 70 HRC, 69.5 HRC, 69 HRC, 68.5 HRC, 68 HRC, 67.5 HRC, 67 HRC or 66.5 HRC.

[0044] In some embodiments, the step-by-step acceleration and deceleration includes: when the process section needs to be accelerated from the threading speed of 40-60m / min to the maximum speed of 150-180m / min, a step-by-step acceleration of the speed is performed every 20-40m / min; when the process section is decelerated from the maximum speed to the tail-swinging speed of 40-90m / min, a step-by-step deceleration of the speed is performed every 20-40m / min.

[0045] Squeeze rollers are a crucial component of the pickling line, playing a crucial role in controlling acid concentration in the pickling tank, ensuring stable pickling operations, and ensuring rinsing results. Push-pull pickling lines, in particular, rely heavily on the push-pull interaction between the squeeze rollers to achieve stable strip threading and subsequent operation.

[0046] Whether it is a push-pull pickling line or a continuous pickling line, the squeeze roller is designed as a rubber roller. During normal production, the squeeze roller runs stably and basically no squeeze roller mark defects will occur. However, when producing special varieties such as high-strength steel, periodic squeeze roller mark defects will appear on the surface of the pickled plate. Therefore, it is necessary to invent a method to control the squeeze roller mark defects.

[0047] Combined with the characteristics that the roller mark defects on the surface of the pickled plate mainly occur at the head and tail, the cause of the roller mark defects of the squeeze roller was further determined. It was mainly due to the large relative friction between the squeeze roller and the strip during the acceleration and deceleration process, which caused the tiny rubber particles of the squeeze roller to fall off under the large friction force and stick to the strip, thus causing the roller mark defects of the squeeze roller.

[0048] Furthermore, to reduce the likelihood of roll marks on the squeeze roller, the friction between the squeeze roller and the strip must be minimized. This is done by reducing the acceleration and deceleration of the squeeze roller during the process, thereby mitigating the impact of instantaneous acceleration and deceleration on the strip surface. For special steel grades, a stepped acceleration and deceleration system is implemented. Furthermore, while ensuring the squeeze roller's effective squeeze and stable torque output, the hardness of the rubber layer on the squeeze roller surface is appropriately increased, maintaining it within the range of 69 ± 2.5 HRC.

[0049] Furthermore, the possibility of tiny rubber particles falling off the squeeze roller under acceleration and deceleration conditions is reduced, thus avoiding the occurrence of squeeze roller marks. On the one hand, while ensuring the hardness of the squeeze roller's rubber layer, the adhesion of the tiny particles is increased to prevent them from falling off. On the other hand, while ensuring the surface quality of the pickled strip, the acid solution temperature is set lower, thereby alleviating the erosion of the high-temperature acid solution on the squeeze roller surface and avoiding the occurrence of squeeze roller marks.

[0050] For example, when the process section needs to be accelerated from a threading speed of 40-60 m / min to a maximum speed of 150-180 m / min, a stepwise acceleration of 20 m / min, 25 m / min, 30 m / min, 35 m / min or 40 m / min is performed.

[0051] When the process section slows down from the highest speed to the tail-swinging speed of 40-90m / min, the speed is decelerated in steps of 20m / min, 25m / min, 30m / min, 35m / min or 40m / min.

[0052] In some embodiments, the preventive steps also include: regularly cleaning the tension roller after the disc shear of the pickling line to reduce foreign matter; formulating key quality equipment replacement and inspection requirements, and regularly replacing the tension roller to prevent the tension roller from being worn too much and causing friction roller mark defects.

[0053] Circular shears are essential equipment in metalworking production lines, primarily used for shearing metal strip. In pickling lines, they are primarily used to cut the strip into a specified width in preparation for subsequent processing steps. The circular shears consist of two disc-shaped blades, one above the other. During operation, the upper and lower disc blades rotate at high speed in the same direction, allowing the metal strip to pass between them. The rotation of the blades is combined with the forward motion of the strip, allowing the sharp edges of the blades to shear the strip.

[0054] During operation, disc shears produce foreign matter such as metal debris and scale, which can easily adhere to the surface of the subsequent tension roller. When the strip contacts the tension roller with foreign matter attached, the foreign matter forms irregular protrusions between the two. Under the action of tension, these protrusions can cause scratches, indentations, and other damage to the strip surface, resulting in friction roller marks. Regular cleaning of the tension roller can promptly remove foreign matter attached to the surface and keep the tension roller surface smooth and flat. This ensures more uniform contact between the strip and the roller surface as it passes through, reducing local pressure fluctuations and friction anomalies caused by foreign matter, thereby effectively reducing the possibility of friction roller marks and ensuring the surface quality of the strip.

[0055] During long-term use, the tension roller will experience surface wear and coating peeling due to friction, extrusion and other forces with the strip. As the degree of wear increases, the roughness and roundness of the tension roller surface change, resulting in uneven distribution of friction between it and the strip. This uneven friction can cause scratches and indentations of varying degrees on the surface of the strip, forming friction roller marks. By formulating key quality equipment replacement and inspection requirements, tension rollers are replaced regularly, and tension rollers with severe wear can be replaced in a timely manner before their wear is severe enough to affect the surface quality of the strip. Using new, high-performance tension rollers ensures the flatness of the roller surface and the uniformity of friction, avoids friction roller marks caused by excessive wear of the tension roller, and also helps maintain the stability and continuity of the entire pickling line production process.

[0056] The tension rollers are mainly responsible for establishing the tension in each section of the production line. Tension roller mark defects mostly occur in the last set of tension rollers. The last set of tension rollers is generally arranged after the circular shear and establishes tension between the coiler to ensure the stability of the outlet tension, which is beneficial to the control of the strip coil shape.

[0057] Further, the common feature of the tension roller mark defects is that most of them occur in the last group of tension rollers. They often occur after failures such as disc shear jams. This is mainly because the broken edge strips fall off and penetrate into the tension roller, causing damage to the tension roller surface, thereby generating periodic tension roller mark defects.

[0058] Furthermore, in order to alleviate the roller mark defects of the tension roller, the probability of the disc shear getting stuck needs to be reduced. At the same time, after the disc shear getting stuck, the tension roller surface should be checked immediately. If foreign objects such as broken strips are found, they should be cleaned up in time to prevent roller mark defects. On the other hand, key quality equipment replacement and inspection requirements should be formulated, and the tension roller should be replaced regularly to prevent friction roller mark defects caused by excessive wear of the tension roller.

[0059] In some embodiments, the correction step includes: inspecting the surface quality of the pickling plate by manual visual inspection or surface quality inspection instruments, and if periodic pickling plate roller mark defects are detected, measuring the roller mark occurrence cycle, locking the roller mark occurrence position according to the production line roller mark cycle table, and performing cleaning or grinding.

[0060] In some embodiments, the correction step further includes: when a squeeze roller mark defect occurs, lowering the acid solution temperature in the pickling section to 75-80° C. to alleviate the erosion of the squeeze roller surface by the high-temperature acid solution.

[0061] The embodiment of the present application uses a method for controlling roller mark defects on pickling plates, which reduces the output rate of pickling plate roller mark defective belts from the previous 0.20% to within 0.05%, thereby enhancing the profitability of pickling products and significantly improving the company's image.

[0062] The present application is described below with reference to specific embodiments.

[0063] Example 1

[0064] In this example, the control of roller mark defects on the surface of S550MC, a high-strength pickled plate for automotive structure, first prevents the occurrence of roller mark defects in the pickled plate in advance, and ultimately achieves effective control of the pickled plate roller mark defects; then, the surface quality of the pickled plate is inspected roll by roll through manual visual inspection or surface quality inspection instruments. Once periodic roller mark defects of the pickled plate occur, the roller mark occurrence cycle is immediately measured, and the roller mark occurrence position is locked according to the production line roller mark cycle table. After that, cleaning or grinding is immediately organized to avoid batch roller mark defects.

[0065] Example 1

[0066] A control method for roller mark defects on the surface of high-strength automotive structural pickling plate S550MC based on a pickling unit, the key control points include the following steps:

[0067] During normal production, a surface quality inspection instrument discovered periodic roller mark defects. The measured roller mark period was 800mm, and the roller mark defect occurred on the upper surface and existed throughout the roll. Based on the roller mark defect of 800mm, the roller diameter causing the roller mark defect was 255mm. According to the roller mark period table, the location where the roller mark defect occurred was the upper roller of the straightening machine's front pinch roller. The production line was immediately shut down, and the roller surface of the upper roller of the straightening machine's front pinch roller was inspected and cleaned, or foreign matter adhered to the roller surface was ground off, thereby eliminating the source of the roller mark defect. The production line was then resumed for confirmation, achieving the goal of avoiding the roller mark defect.

[0068] Example 2

[0069] A control method for roller mark defects on the surface of high-strength automotive structural pickling plate S550MC based on a pickling unit, the key control points include the following steps:

[0070] (1) Control of roller mark defects of the front pinch roller of the straightening machine: Each time the pickling line is inspected, the roller gap accuracy of the front pinch roller of the straightening machine is measured to ensure that the roller gap accuracy of the front pinch roller of the straightening machine is controlled within 0.15mm in the no-load and pressure-down mode, and the roller gap deviation between the operating side and the transmission side shall not exceed 0.05mm; at the same time, the upper and lower roller surfaces of the front pinch roller of the straightening machine are inspected and cleaned every shift to prevent the roller mark defects of the pickling plate caused by foreign matter sticking to the front pinch roller of the straightening machine.

[0071] (2) Control of the squeeze roller mark defect: Reduce the acceleration and deceleration of the squeeze roller in the process section from the original ±0.25 to ±0.167, thereby reducing the impact of instantaneous acceleration and deceleration on the strip surface; at the same time, ensure that the hardness of the colloid layer on the squeeze roller surface is controlled at 69HRC.

[0072] When the squeeze roller mark defect occurs, the acid temperature in the pickling section is lowered from the set 80-85℃ to 75℃ to alleviate the erosion of the high-temperature acid on the roller surface of the squeeze roller; at the same time, when the process section needs to accelerate from the belt threading speed of 40-60m / min to the maximum speed of 150-180m / min, the speed is accelerated step by step every 30m / min; similarly, when the process section is decelerated from the maximum speed to the tail speed of 40-90m / min, the speed is decelerated step by step every 30m / min to alleviate the occurrence of the squeeze roller mark defect.

[0073] Control of squeeze roller mark defects: Before each production shift, the tension roller of the steel channel is inspected and cleaned to avoid the adhesion of foreign matter; at the same time, key quality equipment replacement and inspection requirements are formulated, and the tension roller is replaced regularly; on the other hand, when a fault such as steel jamming in the disc shear occurs, the tension roller surface is immediately inspected, and if foreign matter such as broken slats is found, it is cleaned in time to prevent roller mark defects.

[0074] After following the above control method, no pickling roller mark defects were found.

[0075] The above are only specific embodiments of the present application, but the scope of protection of the present application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and such modifications or substitutions should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A method for controlling roller mark defects on the surface of pickled plates, characterized in that: include: Preventive measures include controlling the operation of the front pinch rolls, squeeze rolls and tension rolls of the pickling line straightener within a preset range; The correction step includes determining the pickling line defects and correcting them based on the defects that have appeared in the pickling plates produced by the pickling line.

2. The method for controlling roller mark defects on the surface of pickled plates according to claim 1, characterized in that: The preventive steps include: Removing foreign matter adhering to the front pinch roller of the straightening machine, wherein the foreign matter includes iron oxide scale; Analyze and remove the reasons why foreign matter is easily adhered to the front pinch roller of the straightening machine, and solve the problem of foreign matter adhesion to the front pinch roller of the straightening machine based on the reasons.

3. The method for controlling roller mark defects on the surface of pickled plate according to claim 2, characterized in that: The preventive steps also include: Each shift, the upper and lower roller surfaces of the front pinch rollers of the straightening machine are inspected and cleaned to remove foreign matter.

4. The method for controlling roller mark defects on the surface of pickled plates according to claim 1, characterized in that: The preventive steps also include: Adjust the front pinch rollers of the straightening machine so that the roller gap accuracy of the front pinch rollers of the straightening machine is controlled within 0.20 mm in the no-load, press-down mode.

5. The method for controlling roller mark defects on the surface of pickled plate according to claim 1, characterized in that: The preventive steps also include: Adjust the front pinch roller of the straightening machine so that after the front pinch roller of the straightening machine is pressed down, the roller gap deviation between the operating side and the transmission side does not exceed 0.05mm.

6. The method for controlling roller mark defects on the surface of pickled plate according to claim 1, characterized in that: The preventive steps also include: Control the acceleration and deceleration of the squeeze roller in the process section to ±0.17m / s 2 -±0.1m / s 2 , to mitigate the impact of instantaneous acceleration and deceleration on the strip surface; For special products, step-by-step acceleration and deceleration are performed during the acceleration and deceleration process; The hardness of the rubber layer on the roller surface of the squeezing roller is controlled within the range of 69±2.5HRC.

7. The method for controlling roller mark defects on the surface of pickled plate according to claim 6, characterized in that: The stepwise acceleration and deceleration includes: When the process section needs to be accelerated from the threading speed of 40-60m / min to the maximum speed of 150-180m / min, a stepwise acceleration of 20-40m / min is performed; When the process section slows down from the highest speed to the tail-swinging speed of 40-90m / min, the speed is decelerated step by step at every 20-40m / min.

8. The method for controlling roller mark defects on the surface of pickled plate according to claim 1, characterized in that: The preventive steps also include: Regularly clean the tension roller after the disc shear of the pickling line to reduce foreign matter; Establish key quality equipment replacement and inspection requirements and replace the tension roller regularly to prevent friction roller mark defects caused by excessive wear of the tension roller.

9. The method for controlling roller mark defects on the surface of pickled plate according to claim 1, characterized in that: The correction steps include: The surface quality of the pickling plate is inspected by manual visual inspection or surface quality inspection instruments. If periodic pickling plate roller mark defects are detected, the roller mark period is measured, and the roller mark position is locked according to the production line roller mark period table, and cleaning or grinding is performed.

10. The method for controlling roller mark defects on the surface of pickled plate according to claim 1, characterized in that: The correction step further comprises: When the squeeze roller has a roller mark defect, reduce the acid temperature in the pickling section to 75-80°C to alleviate the erosion of the high-temperature acid on the squeeze roller surface.