A squeezing roll and a strip pickling process

Abstract

The present invention discloses a squeezing roll and a strip pickling process, belonging to the field of strip pickling. The squeezing roll comprises a cooperating upper squeezing roll and a lower squeezing roll, and the upper squeezing roll and the lower squeezing roll are arranged in a concave-convex roll matching manner, so that when the strip passes through the squeezing roll, a C-shaped warping with a high middle and low ends can be formed, which is convenient for cleaning the residues on the strip surface and improving the surface quality of the strip. The unique pickling process parameters of the strip pickling process can efficiently remove the scale on the strip surface and improve the surface quality of the strip. Moreover, the process uses the above squeezing roll to perform a squeezing operation on the strip, and cooperates with the improved spray pipe and air blowing pipe in the subsequent process, thereby effectively removing the residues on the strip surface and further improving the surface quality of the strip.

Description

Technical Field

[0001] The present invention belongs to the field of strip pickling, and more specifically, relates to a squeezing roll and a strip pickling process. Background Art

[0002] The hot-rolled strip coils produced by a hot rolling mill are rolled and coiled. The scale formed on the strip surface under corresponding conditions can firmly cover the strip surface and cover the defects on the strip surface.

[0003] From the perspective of steel rolling, if the strip with scale is directly sent to a cold rolling mill for rolling, many problems will occur: First, when rolling under a large amount of downward pressure, the scale will be pressed into the strip matrix, affecting the surface quality and processing performance of the cold rolled sheet, and even causing rejects; Second, after the scale is broken, it enters the emulsion system of the cooling and lubricating rolling rolls, which will damage the circulation equipment and shorten the service life of the emulsion; Third, it will damage the cold rolling rolls with very high surface finish and processing accuracy and high prices. Therefore, before cold rolling, the scale on the strip surface must be removed to ensure the surface quality of the produced cold rolled strip. In the prior art, generally, the strip pickling process is used to remove the scale on the strip surface.

[0004] The strip pickling process includes multiple processes such as pickling, rinsing, squeezing, and drying. However, in actual production, it is found that defects such as black spots and black patches often appear on the upper surface of the produced strip. After analysis, the reasons for the defects are as follows: In the existing strip pickling process, flat rolls are basically used for the squeezing rolls. When the strip flows between the upper and lower squeezing rolls, due to the weight of the strip itself, the strip will rub against the middle part of the lower roll and cause a certain degree of wear to the middle part of the lower roll, resulting in a certain degree of depression in the middle part of the lower roll. When the strip is squeezed by the squeezing roll, it will form a C-shaped upward warping with a lower middle and higher ends, which is not conducive to the flow of the residual acid and iron oxide powder on the upper surface of the strip, resulting in the residues remaining on the strip, damaging the strip, and causing the above-mentioned defects. Moreover, there is no good solution to this problem in the prior art.

[0005] For example, the Chinese patent application number is CN201310447375.8, and the publication date is April 13, 2015. The patent document discloses a super wear-resistant squeeze roller, and the effective components thereof are as follows: 100 parts of Hypalon rubber; 25-35 parts of white carbon black; 10-15 parts of titanium dioxide; 4-6 parts of magnesium oxide; 3-5 parts of accelerator; 2-3 parts of vulcanizer; 3-7 parts of quartz powder. The super wear-resistant squeeze roller described in the invention has high wear resistance and long service life, can adapt to the rough surface of the strip steel and the production environment with high tension, and is not easy to generate a large amount of rubber residues during the friction between the roller surface and the strip steel surface, thereby preventing the defect of foreign matter pressing into the strip steel surface and improving the quality of the strip steel product. However, although the squeeze roller of the invention has a certain wear resistance due to the improvement of the material, it is still inevitable that the middle part of the lower squeeze roller will be sunken in actual operation, and the above-mentioned surface defects of the strip steel will easily occur as long as a slight sunken state occurs, and the squeeze roller can maintain the optimal working time for a short time. In addition, the material of the squeeze roller is a specially designed material that cannot be purchased, which makes the squeeze roller generate more manufacturing costs.

[0006] Another example is the patent document with Chinese patent application number: CN201320749162.6, published on August 27, 2014, which discloses a cold rolling pickling and squeezing roller device, including a cylindrical roller body and a roller sleeve covering the outer layer of the roller body, the length of the roller sleeve is ≥ the length of the roller body, and the outer surface of the roller sleeve is concave at both ends. The overall outer surface of the utility model is a concave arc structure that bends inward, the middle part of which fits tightly with the middle part of the strip steel, and the two ends can contact the strip steel with thinning areas at both ends, effectively remove the residue on the surface of the strip steel, and have a good squeezing effect, good cleaning effect, effectively reduce the surface residue of the strip steel, especially avoid the surface residue of the strip steel edge, reduce the generation of defects such as yellow rust on the strip steel edge, and improve the pickling quality of the strip steel. However, the device is mainly used for removing residues on the edge of the strip. Long-term operation of the strip will also cause wear to the middle part of the lower squeezing roller and form a depression in the middle part of the lower squeezing roller, causing the strip to be C-shaped and high at both ends after passing through the squeezing roller. Therefore, the device cannot solve the above-mentioned problem that residues on the strip surface are difficult to remove.

[0007] In addition, the above two devices do not provide a specific description of the spray pipe and the air blow pipe in the strip pickling process, and the spray pipe and the air blow pipe in the prior art generally adopt the form of a straight pipe, which is not very effective in cleaning the acid residues on the surface of the strip. Summary of the invention

[0008] 1. Problems to be solved

[0009] In view of the problem that residues such as acid solution and iron oxide powder in the existing strip pickling process are difficult to remove, which affects the surface quality of the strip, the present invention provides a squeezing roll. By improving the structure of the squeezing roll, the problem of difficult removal of residues on the strip surface can be effectively solved, and the surface quality of the produced strip can be improved.

[0010] The present invention also provides a strip pickling process. Its unique pickling process parameters can efficiently remove the mill scale on the strip surface, improve the surface quality of the strip, and this process uses the above-mentioned squeezing roll to perform a squeezing operation on the strip, and cooperates with the improved spray pipe and air blowing pipe in the subsequent process, so as to effectively remove the residues on the strip surface and further improve the surface quality of the strip.

[0011] 2. Technical solutions

[0012] To solve the above problems, the present invention adopts the following technical solutions.

[0013] A squeezing roll includes an upper squeezing roll and a lower squeezing roll. The upper squeezing roll includes an upper roll body and an upper roll main shaft. The lower squeezing roll includes a lower roll body and a lower roll main shaft. A shaft hole penetrating the upper roll body is provided at the axis center of the upper roll body. The upper roll main shaft passes through the shaft hole of the upper roll body and is connected to the upper roll body. A shaft hole penetrating the lower roll body is provided at the axis center of the lower roll body. The lower roll main shaft passes through the shaft hole of the lower roll body and is connected to the lower roll body. The diameter of the upper roll body gradually decreases from both ends to the middle, and the diameter of the lower roll body gradually increases from both ends to the middle.

[0014] As a further improvement of the technical solution, the surface of the upper roll body is coated with an upper roll rubber layer corresponding to the shape of the upper roll body, and the surface of the lower roll body is coated with a lower roll rubber layer corresponding to the shape of the lower roll body.

[0015] As a further improvement of the technical solution, retaining rings are installed on both sides of the upper roll main shaft and the lower roll main shaft.

[0016] As a further improvement of the technical solution, the axial lengths of both the upper roll body and the lower roll body are 2250 - 2350 mm, the difference between the diameter of the middle section and the diameters of both ends of the upper roll body is 3.8 - 4.2 mm, and the difference between the diameter of the middle section and the diameters of both ends of the lower roll body is 3.8 - 4.2 mm.

[0017] A strip pickling process includes the following steps:

[0018] I. Pickling

[0019] The strip after annealing treatment enters the pickling tank for pickling to remove the mill scale on the strip surface;

[0020] II. Rinsing

[0021] The pickled strip steel enters the rinsing tank for rinsing. The spray pipes spray rinsing water to wash the residues on the surface of the strip steel, and the rinsing water after rinsing flows into the rinsing tank.

[0022] III. Squeezing Dry

[0023] During the rinsing process, the strip steel passes through the squeezing rollers located above the rinsing tank, and the residual liquid on the surface of the strip steel is squeezed out under the action of the squeezing rollers.

[0024] IV. Drying

[0025] The strip steel after squeezing dry enters the drying equipment located behind the rinsing tank, and the drying equipment performs drying operation on the surface of the strip steel.

[0026] The squeezing rollers in step III are one of the squeezing rollers described in the above technical solution.

[0027] As a further improvement of the technical solution, the spray pipes in step II are V-shaped water pipes arranged above the rinsing tank, and a plurality of nozzles are arranged at equal intervals on the V-shaped water pipes; the bending part of the V-shaped water pipe is arranged in the middle of the rinsing tank, and its opening gradually increases along the movement direction of the strip steel.

[0028] As a further improvement of the technical solution, a connecting rod is installed between the V-shaped water pipes.

[0029] As a further improvement of the technical solution, the drying equipment in step IV includes a V-shaped air blowing pipe arranged above the strip steel and a steam drying device, and the air outlet of the steam drying device is communicated with the air inlet of the V-shaped air blowing pipe; the bending part of the V-shaped air blowing pipe is arranged in the middle of the width of the strip steel, and its opening gradually increases along the movement direction of the strip steel.

[0030] As a further improvement of the technical solution, hydrochloric acid is used as the pickling solution in step I, and the temperature of the hydrochloric acid is 80 - 85 °C.

[0031] As a further improvement of the technical solution, the water spraying pressure of the spray pipes in step II is 0.4 - 0.6 MPa, and the temperature is 60 - 85 °C.

[0032] As a further improvement of the technical solution, the material of the strip steel is No. 45 steel.

[0033] As a further improvement of the technical solution, the thickness of the strip steel is 1.5 - 6 mm, and the width is 850 - 2000 mm.

[0034] As a further improvement of the technical solution, the temperature of the gas blown out by the V-shaped air blowing pipe is 100 - 120 °C.

[0035] 3. Beneficial Effects

[0036] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0037] (1) For an extrusion roller of the present invention, the structure of the extrusion roller is changed into a concave-convex roller form with upper and lower cooperation. When the extrusion roller performs an extrusion operation on the strip steel, the strip steel will undergo elastic deformation within the yield stress, forming an arc structure with a certain convexity, so that the pickling solution remaining on the surface of the strip steel can smoothly flow to both sides of the strip steel along the curvature. In addition, although the middle part of the lower extrusion roller will be worn with the strip steel during long-term use, when the wear degree does not exceed a certain level so that the diameter of the middle part of the lower extrusion roller is lower than that of both ends, the extrusion roller can still maintain an excellent extrusion effect on the strip steel, and there will be no problem that as long as the middle part of the lower roller has a depression in the traditional flat roller, some residual pickling solution will inevitably be difficult to remove due to this depression, and this part of the pickling solution that is difficult to remove is also very difficult to clean perfectly in the subsequent cleaning process;

[0038] (2) For an extrusion roller of the present invention, a rubber layer corresponding to the shape of the upper and lower extrusion rollers is coated on the surfaces of the upper and lower extrusion rollers. The thickness of each part of the rubber layer is kept consistent, so the convexity and concavity formed by it are the same as those of the roller body of the extrusion roller, and it can also maintain an excellent extrusion effect on the strip steel. In addition, the material of the rubber layer is a replaceable wear-resistant material, which greatly improves the service life of the extrusion roller, avoids the situation that the whole roller needs to be replaced after the extrusion roller is damaged, and reduces the production cost of the strip steel;

[0039] (3) For an extrusion roller of the present invention, retaining rings are sleeved on both sides of the main shaft of the extrusion roller. The retaining rings can effectively block the splashing pickling solution squeezed to both sides during the operation of the extrusion roller, avoiding the pickling solution from splashing onto the equipment on both sides, thus saving the time and labor for manually cleaning the pickling solution on the equipment and avoiding the danger of the splashing pickling solution damaging the equipment;

[0040] (4) For an extrusion roller of the present invention, through a large number of experiments and production practices, the appropriate range of convexity and concavity of the extrusion roller is summarized. The strip steel under the action of the extrusion roller with this specific convexity and concavity can maintain an excellent effect of cleaning the pickling solution without undergoing plastic deformation outside the yield stress, so that the strip steel can automatically return to a flat state after the pickling process, ensuring the subsequent processing effect and quality of the strip steel. In particular, the extrusion effect on strip steel with a specific thickness and width is extremely obvious;

[0041] (5) For a strip steel pickling process of the present invention, using the above-mentioned extrusion roller to perform an extrusion operation on the strip steel in the pickling process can effectively remove the pickling solution remaining on the strip steel during pickling while ensuring the cleaning effect of the iron oxide scale on the surface of the strip steel, and ensure the surface quality of the processed strip steel;

[0042] (6) The pickling process of strip steel in the present invention changes the traditional straight spray pipe into a V-shaped water pipe. Since the bent end of the V-shaped water pipe is located in the middle of the rinsing tank and its opening direction gradually increases along the moving direction of the strip steel, when the strip steel moves, the middle part of the strip steel will come into contact with the sprayed rinsing water first. As a result, residues in the middle of the strip steel, such as pickling solution or iron oxide powder that were not cleaned thoroughly in the previous process, can flow towards both sides of the strip steel under the water pressure of the sprayed rinsing water. As the strip steel moves further, both sides of the middle part of the strip steel gradually come into contact with the rinsing water sprayed from the V-shaped water pipe, so that the residues gradually flow out of the strip steel from both sides, with excellent cleaning effect and the residues being basically cleaned up. In addition, the present invention also connects a connecting rod between the V-shaped water pipes. The effect of this connecting rod is the same as that of a strengthening beam, effectively strengthening the connection strength of the V-shaped water pipes and preventing the stability of the water pipes from being affected due to this V-shaped structure;

[0043] (7) In the pickling process of strip steel in the present invention, since a water film will remain on the surface of the strip steel after rinsing, it is necessary to dry its surface. By transforming the air blowing pipe of the drying equipment into a V-shaped air outlet pipe with the same structure and installation method as the V-shaped water pipe, the water on the surface of the strip steel will flow towards both sides of the strip steel under the action of the V-shaped gas during the drying process. In this way, the drying efficiency and drying effect of the drying equipment are effectively enhanced. Description of the Drawings

[0044] Figure 1 is the working schematic diagram of the squeezing roller of the present invention;

[0045] Figure 2 is the structural schematic diagram of the upper squeezing roller of the present invention;

[0046] Figure 3 is the structural schematic diagram of the lower squeezing roller of the present invention;

[0047] Figure 4 is the structural schematic diagram of the rinsing section of the present invention;

[0048] In the figure: 1. Upper squeezing roller; 11. Upper roller body; 12. Upper roller main shaft; 13. Upper roller rubber layer; 2. Lower squeezing roller; 21. Lower roller body; 22. Lower roller main shaft; 23. Lower roller rubber layer; 3. Retaining ring; 4. Squeezing roller; 5. V-shaped water pipe; 51. Connecting rod; 6. Strip steel. Detailed Embodiments

[0049] The present invention will be further described below in conjunction with specific embodiments and the drawings.

[0050] Embodiment 1

[0051] As Figure 1As shown in the figure, a squeezing roller is mainly used to squeeze the strip steel pickled in the pickling tank up and down to squeeze out the residual pickling solution on the surface of the strip steel. It is arranged in the rinsing stage of the strip steel pickling process and includes an upper squeezing roller 1 and a lower squeezing roller 2. Among them, the upper squeezing roller 1 is located at the upper end of the plane where the strip steel is located, and the lower squeezing roller 2 is located at the lower end of the plane where the strip steel is located.

[0052] Traditional squeezing rollers generally adopt the form of flat rollers. The advantage of flat rollers is mainly that they are relatively convenient to process. However, during the long-term operation of the squeezing roller, wear will occur between the squeezing roller and the strip steel. As a result, a depression will form in the middle of the lower squeezing roller 2, causing the strip steel to form a C-shaped upward warping with a lower middle and higher ends under the extrusion of the upper and lower squeezing rollers when passing through the squeezing roller. The pickling solution remains in the middle of the strip steel due to the arc of the C-shaped upward warping and is difficult to be squeezed to both sides of the strip steel by the squeezing roller. In the prior art, this problem is generally solved by replacing the material of the squeezing roller with wear-resistant material or covering the surface of the squeezing roller with a wear-resistant layer, but this cannot solve this problem well. Because although it is a wear-resistant material, wear will still occur between the squeezing roller and the strip steel and a depression will form. As long as a depression occurs, the squeezing effect of the squeezing roller on the strip steel will be greatly reduced. Therefore, in view of this problem, in this embodiment, by improving the structure of the squeezing roller, the problem that the pickling solution is difficult to flow to both sides of the strip steel due to the wear between the strip steel and the squeezing roller is effectively solved. The following will respectively describe in detail the specific structures of the upper squeezing roller 1 and the lower squeezing roller 2 of this embodiment.

[0053] As Figure 2 and Figure 3 shown in the figure, the upper squeezing roller 1 includes an upper roller body 11 and an upper roller main shaft 12. A shaft hole penetrating the upper roller body 11 is provided at the axis of the upper roller body 11. The upper roller main shaft 12 passes through the shaft hole of the upper roller body 11 and is connected to the upper roller body 11. The connection method can adopt common fixed connection methods in the prior art such as key connection and welding. In this embodiment, welding is adopted. The upper roller body 11 is a cylindrical structure with a smaller diameter in the middle and larger diameters at both ends, and its diameter gradually decreases from both ends to the middle in an arc-shaped structure. The lower squeezing roller 2 includes a lower roller body 21 and a lower roller main shaft 22. A shaft hole penetrating the lower roller body 21 is provided at the axis of the lower roller body 21. The lower roller main shaft 22 passes through the shaft hole of the lower roller body 21 and is connected to the lower roller body 21. In this embodiment, the connection method is adopted by welding. The lower roller body 21 is a cylindrical structure with a larger diameter in the middle and smaller diameters at both ends that matches the upper roller body 11, and its diameter gradually increases from both ends to the middle in an arc-shaped state. The upper roller body 11 and the lower roller body 21 can fit tightly together. The installation methods of the upper squeezing roller 1 and the lower squeezing roller 2 are the same. Both are connected to the output shaft of the motor through bearings at one end and supported and installed on the racks on both sides of the strip steel through bearings at the other end, and rotate by the drive of the motor. Both ends of the squeezing roller are located on both sides of the strip steel.

[0054] When the squeezing rollers are working, the upper squeezing roller 1 and the lower squeezing roller 2 approach and squeeze the strip steel located between the upper squeezing roller 1 and the lower squeezing roller 2. Since the body 11 of the upper roller and the body 21 of the lower roller are in a concave-convex roller structure that cooperate with each other, when the strip steel passes through the upper squeezing roller 1 and the lower squeezing roller 2, an arc structure with a middle bulge will be formed, so that the pickling solution can smoothly slide from the middle of the strip steel to both sides and flow out of the strip steel, avoiding the risk of damage to the strip steel caused by the pickling solution remaining on the strip steel. In particular, in this form of concave-convex roller cooperation, even if there is still wear between the middle part of the body 21 of the lower roller and the strip steel, its convex structure can smoothly offset this part of the wear, and there will be no problem of a middle depression formed due to wear. The pickling solution on the surface of the strip steel can still smoothly flow out of the strip steel, or it takes a particularly long time of use to wear down the convexity. During this period, the squeezing rollers can always maintain a better squeezing effect, which is about 3 times longer than the better service time of ordinary squeezing rollers.

[0055] However, considering that the strip steel has a certain yield stress, it is very difficult for the deformed strip steel exceeding the yield stress to return to a flat state again. Therefore, the range of the concavity and convexity of the squeezing rollers needs to be limited, while maintaining an excellent squeezing effect on the strip steel by the squeezing rollers and ensuring that the strip steel can return to a flat state after squeezing. The steel type used in this embodiment is No. 45 steel. Therefore, this embodiment limits the concavity and convexity of the squeezing rollers for this steel type of steel. Through the summary of a large number of experiments and production practices, it is found that when the axial length of the body of the squeezing rollers (including the upper squeezing roller and the lower squeezing roller) is between 2250 mm and 2350 mm, and the difference between the diameter of the middle section and the diameters of both ends of the body is between 3.8 mm and 4.2 mm, it has an excellent squeezing effect on strip steel with a thickness of 1.5 mm to 6 mm and a width of 850 mm to 2000 mm. The remaining pickling solution can be basically cleaned up, and the strip steel can completely return to a flat state. The following are several groups of specific data:

[0056] 1) The thickness of the strip steel is 1.5 mm, the width is 850 mm, the axial length of the body of the squeezing roller is 2250 mm, the difference between the diameter of the middle section and the diameters of both ends of the body is 3.8 mm, the pickling solution on the surface of the strip steel is basically cleaned up, and the strip steel can return to a flat state;

[0057] 2) The thickness of the strip steel is 4 mm, the width is 1400 mm, the axial length of the body of the squeezing roller is 2300 mm, the difference between the diameter of the middle section and the diameters of both ends of the body is 4 mm, the pickling solution on the surface of the strip steel is basically cleaned up, and the strip steel can return to a flat state;

[0058] 3) The strip thickness is 6 mm, the width is 2000 mm, the axial length of the roll body of the squeegee roll is 2350 mm, the difference between the diameter of the middle section and the diameters at both ends of the roll body is 4.2 mm, the pickling solution on the strip surface is basically removed, and the strip can return to a flat state;

[0059] 4) The strip thickness is 1.3 mm, the width is 1500 mm, the axial length of the roll body of the squeegee roll is 2200 mm, the difference between the diameter of the middle section and the diameters at both ends of the roll body is 3.6 mm, there is some residue of the pickling solution on the strip surface, and the strip can return to a flat state;

[0060] 5) The strip thickness is 7 mm, the width is 1500 mm, the axial length of the roll body of the squeegee roll is 2400 mm, the difference between the diameter of the middle section and the diameters at both ends of the roll body is 4.5 mm, the pickling solution on the strip surface is basically removed, and part of the strip cannot return to a flat state.

[0061] In order to further improve the use effect of the squeegee roll, in this embodiment, a layer of upper roll rubber layer 13 and a lower roll rubber layer 23 are respectively coated on the surfaces of the upper roll body 11 and the lower roll body 21. The rubber layer is made of wear-resistant material and is matched with the shape of the roll body of the squeegee roll. The thickness of the rubber layer at each position is the same. Therefore, the concavity and convexity formed by the upper roll rubber layer 13 and the lower roll rubber layer 23 can be consistent with the concavity and convexity of the squeegee roll, and can also maintain the squeezing effect on the strip and make the strip in an elastic deformation within the yield stress, and greatly extend the service life of the squeegee roll. In this embodiment, Hypalon is used as the material for making the rubber layer, and this material is also known as chlorosulfonated polyethylene.

[0062] In addition, since there will be a large acting force during the process of the squeegee roll squeezing the strip, the pickling solution on the strip surface will splash to both sides of the strip under the extrusion of the squeegee roll. The pickling solution splashed onto the equipment on both sides of the strip will damage the surface of the equipment and is relatively troublesome to clean. Therefore, in this embodiment, retaining rings 3 are installed at both ends of the upper roll main shaft 12 and the lower roll main shaft 22. The retaining ring 3 is a ring structure and is welded on both sides of the main shaft of the squeegee roll. When the squeegee roll is working, the pickling solution splashed from the strip can be blocked by the retaining ring 3, avoiding the situation that the splashed pickling solution damages the equipment on both sides of the strip.

[0063] In summary, a squeegee roll of this embodiment can effectively solve the problem that it is difficult to remove the pickling solution on the strip surface due to the wear between the squeegee roll and the strip, improve the surface quality of the strip, and has an extremely long service life.

[0064] Embodiment 2

[0065] A strip pickling process is used to process steel strips with a width of 850 - 2000 mm and a thickness of 1.5 - 6 mm. In this embodiment, a steel strip with a thickness of 3 mm and a width of 1500 mm, which is No. 45 steel, is used. The main purpose is to remove the scale formed on the surface of the strip after annealing treatment and remove residues such as pickling solution and iron oxide powder on the strip surface in subsequent processes. It includes steps such as pickling, rinsing, squeezing, and drying. The specific process is as follows:

[0066] I. Pickling

[0067] A layer of scale will form on the surface of the strip after hot rolling. The scale is mainly composed of Fe2O3 in the outermost layer, Fe3O4 in the middle layer, and FeO in the innermost layer. Since this scale will have a greater impact on the strip quality and rolling equipment during the subsequent rolling process of the strip, pickling is required to remove it. Traditional pickling solutions generally use hydrochloric acid or sulfuric acid. Compared with sulfuric acid, hydrochloric acid has the advantages of faster reaction with scale, lower cost, and greater solubility of the iron salts generated during the reaction. Therefore, hydrochloric acid is used as the pickling solution in this embodiment, which can effectively improve the pickling efficiency of the strip.

[0068] In this embodiment, a total of three sections of pickling tanks are set. The hydrochloric acid concentration in the pickling tanks gradually increases along the moving direction of the strip. The usage standards of hydrochloric acid in the three sections of pickling tanks are as follows: the hydrochloric acid concentration in the first section of pickling tank is 35 - 45 g / l, the hydrochloric acid concentration in the second section of pickling tank is 50 - 80 g / l, and the hydrochloric acid concentration in the third section of pickling tank is 100 - 130 g / l. The hydrochloric acid temperature in the three sections of pickling tanks is controlled at 80 - 85 °C. In this embodiment, a set of hydrochloric acid parameters with relatively prominent pickling effects is adopted, that is, the hydrochloric acid concentration in the first section is 40 g / l and the temperature is 80 °C; the hydrochloric acid concentration in the second section is 65 g / l and the temperature is 82 °C; the hydrochloric acid concentration in the third section is 115 g / l and the temperature is 85 °C. These hydrochloric acid parameters can efficiently remove the scale on the strip surface and improve the pickling efficiency.

[0069] II. Rinsing and squeezing

[0070] It should be noted that rinsing and squeezing are operations carried out simultaneously. As Figure 4As shown in the figure, multiple sets of squeezing rollers 4 are installed at equal intervals along the moving direction of the strip steel 6 on the upper edge of the rinsing tank. In this embodiment, a total of four sets of squeezing rollers 4 are adopted. Above the rinsing tank between two adjacent sets of squeezing rollers 4, a V-shaped water pipe 5 is installed. The bending part of the V-shaped water pipe 5, that is, the top of the "V", is arranged in the middle of the rinsing tank. Starting from the bending part, the V-shaped water pipe 5 extends gradually from the opening along the moving direction of the strip steel 6 to both sides of the strip steel, and a plurality of nozzles are arranged at equal intervals on it. This design of the spray pipe enables the middle part of the strip steel 6 to come into contact with the sprayed rinsing water first when the strip steel 6 is moving, so that the residues in the middle part of the strip steel 6, such as the pickling solution or iron oxide powder that was not cleaned up in the previous process, can flow towards both sides of the strip steel 6 under the water pressure of the sprayed rinsing water. As the strip steel 6 moves further, the two sides of the middle part of the strip steel 6 gradually come into contact with the rinsing water sprayed from the V-shaped water pipe 5, so that the residues flow out of the strip steel 6 from both sides step by step, and the cleaning effect is excellent, and the residues are basically cleaned up. However, this V-shaped water pipe is not stable. Therefore, in this embodiment, a connecting rod 51 is connected between the V-shaped water pipes 5, and the effect of this connecting rod 51 is the same as that of a strengthening beam, thus effectively strengthening the connection strength of the V-shaped water pipes 5 and preventing the stability of the water pipes from being affected due to this V-shaped structure. The rinsing water sprayed by the spray pipe in this embodiment is demineralized water, the spraying water pressure is 0.5 MPa, and the temperature is 70 °C. Under this condition, the demineralized water has a good cleaning effect on the surface of the strip steel 6.

[0071] It should be noted that the squeezing roller 4 in this step adopts one of the squeezing rollers in Embodiment 1, and in cooperation with the design of the V-shaped water pipe 5, the strip steel 6 is rinsed multiple times, and the cleaning effect on the residues on the surface of the strip steel 6 is excellent, and basically no residues that will affect the subsequent processing of the strip steel 6 will be left, thereby improving the quality of the produced strip steel 6. And the last set of squeezing rollers 4 is arranged at the outlet of the rinsing tank, and the number is three pairs, so as to ensure the squeezing effect on the residual liquid on the strip steel surface to the greatest extent.

[0072] III. Drying

[0073] After rinsing and squeezing, the residues on the surface of the strip steel have been basically cleaned up, but there will inevitably still be a water film on the surface. Therefore, it is necessary to perform a drying operation on the surface of the strip steel. If the residues on the surface of the strip steel were not cleaned up in the previous process, the residues will be dried and adhered to the surface of the strip steel during the drying step, and will affect the quality of the strip steel in the subsequent rolling process.

[0074] The drying equipment includes a V-shaped air blowing pipe arranged above the strip steel and a steam drying device. The air outlet of the steam drying device is communicated with the air inlet of the V-shaped air blowing pipe. The specific arrangement mode of the V-shaped air blowing pipe is the same as that of the V-shaped water pipe 5 in Step 2. Since the installation mode of the steam drying device belongs to the common prior art in the strip steel pickling process, no detailed description is given here. The key improvement in this step is mainly on the V-shaped air blowing pipe. A row of nozzles is arranged at equal intervals on the V-shaped air blowing pipe. Through the air blowing pipe with this structure, like the V-shaped water pipe 5 in Step 2, water can be blown from the middle of the strip steel to both sides of the strip steel, and the surface of the strip steel can be dried under the high temperature of the blown gas itself. The gas temperature in this embodiment is 110°C, and the drying effect on the surface of the strip steel is excellent.

[0075] In summary, for a strip steel pickling process in this embodiment, its unique pickling process parameters can efficiently remove the scale on the surface of the strip steel and improve the surface quality of the strip steel. Moreover, this process uses the squeezing roller in Embodiment 1 to perform the squeezing operation on the strip steel, and cooperates with the improved spray pipe and air blowing pipe in the subsequent process, thereby effectively removing the residues on the surface of the strip steel and further improving the surface quality of the strip steel.

[0076] The examples described in the present invention are only descriptions of the preferred embodiments of the present invention, and do not limit the concept and scope of the present invention. Without departing from the design idea of the present invention, various deformations and improvements made by those skilled in the art to the technical solutions of the present invention shall fall within the protection scope of the present invention.

Claims

1. A squeezing roll, comprising an upper squeezing roll (1) and a lower squeezing roll (2). The upper squeezing roll (1) includes an upper roll body (11) and an upper roll main shaft (12), and the lower squeezing roll (2) includes a lower roll body (21) and a lower roll main shaft (22). A shaft hole penetrating through the upper roll body (11) is provided at the axis of the upper roll body (11). The upper roll main shaft (12) passes through the shaft hole of the upper roll body (11) and is connected to the upper roll body (11). A shaft hole penetrating through the lower roll body (21) is provided at the axis of the lower roll body (21). The lower roll main shaft (22) passes through the shaft hole of the lower roll body (21) and is connected to the lower roll body (21). It is characterized in that: The diameter of the upper roll body (11) gradually decreases from both ends to the middle, and the diameter of the lower roll body (21) gradually increases from both ends to the middle; The surface of the upper roll body (11) is coated with an upper roll rubber layer (13) corresponding to the shape of the upper roll body (11), and the surface of the lower roll body (21) is coated with a lower roll rubber layer (23) corresponding to the shape of the lower roll body (21); Circlips (3) are installed on both sides of the upper roll main shaft (12) and the lower roll main shaft (22).

2. The squeezing roller according to claim 1, characterized in that: The axial lengths of the upper roll body (11) and the lower roll body (21) are both 2250 - 2350 mm, and the differences between the diameters of the middle sections and the diameters of both ends of the upper roll body (11) and the lower roll body (21) are both 3.8 - 4.2 mm.

3. A strip pickling process, comprising the following steps: I. Pickling The annealed strip enters the pickling tank for pickling to remove the scale on the strip surface; II. Rinsing The pickled strip enters the rinsing tank for rinsing. The spray pipe sprays rinsing water to wash the residues on the strip surface, and the rinsed rinsing water flows into the rinsing tank; III. Squeezing dry During the rinsing process, the strip passes through the squeezing roll (4) located above the rinsing tank, and under the action of the squeezing roll (4), the residual liquid on the strip surface is squeezed out; IV. Drying The squeezed strip enters the drying equipment located behind the rinsing tank, and the drying equipment performs a drying operation on the strip surface; The squeezing roll (4) in step III is a squeezing roll as described in claim 1 or 2; The spray pipe in step II is a V-shaped water pipe (5) arranged above the rinsing tank. A plurality of nozzles are equidistantly arranged on the V-shaped water pipe (5); the bending part of the V-shaped water pipe (5) is arranged in the middle of the rinsing tank, and its opening gradually increases along the movement direction of the strip.

4. A strip pickling process according to claim 3, characterized in that: A connecting rod (51) is installed between the V-shaped water pipes (5).

5. A strip pickling process according to claim 3, characterized in that: The drying equipment in step IV includes a V-shaped air blowing pipe arranged above the strip and a steam drying device. The air outlet of the steam drying device is communicated with the air inlet of the V-shaped air blowing pipe; the bending part of the V-shaped air blowing pipe is arranged in the middle of the strip width, and its opening gradually increases along the movement direction of the strip.

6. A strip pickling process according to any one of claims 3 to 5, characterized in that: In step I, hydrochloric acid is used as the pickling solution, and the temperature of the hydrochloric acid is 80 - 85 °C.

7. A strip pickling process according to any one of claims 3-5, characterized in that: In step II, the water spraying pressure of the spray pipe is 0.4 - 0.6 MPa, and the temperature is 60 - 85 °C.

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