A method for producing ultra-thin silicon steel having a thickness of 0.15 mm or less on a continuous annealing coating line

Abstract

This invention discloses a method for producing ultra-thin silicon steel with a thickness of less than 0.15 mm on a continuous annealing coating line. The method includes the following steps: uncoiling → strip shearing → welding → cleaning → annealing → coating → drying → cooling → coiling. This method can successfully complete the continuous annealing coating production of ultra-thin silicon steel with a thickness of 0.15 mm and below, solving the technical problems of uncoiling, welding, and shearing in the production of ultra-thin silicon steel with a thickness of 0.15 mm and below. It effectively avoids production failures such as strip deviation, wrinkling, shaking and tearing during the production process, and solves the smooth operation problem of mass production of ultra-thin silicon steel, enabling ordinary continuous annealing coating lines to also have the production capacity of ultra-thin silicon steel.

Description

Technical Field

[0001] This invention belongs to the field of ultra-thin silicon steel technology, specifically relating to a method for producing ultra-thin silicon steel with a thickness of less than 0.15 mm on a continuous annealing coating line. Background Technology

[0002] Silicon steel, also known as electromagnetic steel or electrical steel, refers to silicon alloy steel containing 0.5% to 4.5% silicon and less than 0.003% carbon in finished products. Due to its special properties, namely high permeability, low coercivity, high resistivity, and low hysteresis loss, it is mainly used to manufacture the cores of various generators and motors, transformers, relays, and various electrical instruments. Common silicon steel products on the market are generally 0.18mm or thicker, while producing silicon steel products with even thinner thicknesses can help products enter the high-end market, such as in the fields of drones and high-speed motors.

[0003] Silicon steel products are generally produced through a continuous annealing and coating line after rolling. The continuous annealing furnace and coating drying furnace on the continuous annealing and coating line are composed as follows: Figure 1 As shown. In production practice, the applicant found that producing ultra-thin silicon steel (below 0.15mm) on a continuous annealing coating line presents significant challenges in smooth production, primarily in the following aspects: 1) Coiling: The strip is too thin, causing it to arch during conveying, making it difficult to move smoothly over guide rollers, pinch rollers, etc. Double-layer shears and welding shears may fail to cut it, affecting normal welding time; 2) Welding: Silicon steel sheets thinner than 0.15mm exceed the welding capacity of existing Taylor double-welding wheel narrow lap welding machines. Without suitable welding parameters, weld quality cannot be guaranteed; 3) Cleaning section: The cleaning section has numerous guide rollers, squeeze rollers, brush rollers, etc., making it prone to deviation during operation, leading to wrinkling and tearing; 4) Drying device in the cleaning section and cooling section after the annealing furnace: The blowers cause the strip to vibrate, easily leading to tearing; 6) Coiling: Flying shears may fail to cut it, the strip head may arch when conveyed to the coiler, and the coil may collapse after coiling.

[0004] The continuous annealing and coating line for silicon steel is a continuous production line. Due to the high temperature inside the furnace, which can reach up to 1020℃, if the process section slows down or stops during production, the strip steel produced during that period will be overheated and scrapped. The occurrence of the above situation will greatly increase the scrap rate.

[0005] However, existing technologies do not provide effective solutions to the aforementioned problems encountered in the production of ultra-thin silicon steel with a thickness of less than 0.15mm. Summary of the Invention

[0006] To solve the above-mentioned technical problems, the present invention provides a method for producing ultra-thin silicon steel with a thickness of less than 0.15 mm on a continuous annealing coating line. This method can successfully produce ultra-thin silicon steel with a thickness of less than 0.15 mm, and there will be no problems such as strip wrinkling, deviation, poor weld quality, strip breakage, burning, or collapse after coiling during the production process. The silicon steel produced is of good quality.

[0007] The technical solution adopted in this invention is as follows:

[0008] A method for producing ultra-thin silicon steel with a thickness of less than 0.15 mm on a continuous annealing and coating line, the method comprising the following steps: uncoiling → strip shearing → welding → cleaning → annealing → coating → drying → cooling → coiling;

[0009] During rolling, the thickness of the strip at the beginning and end, 25-35m, is controlled between the target rolling thickness and 0.05-0.1mm, and then uncoiling, strip shearing, and welding are carried out.

[0010] During the cleaning step, the squeeze roller is put into normal use, and the pressure on both sides of the squeeze roller is guaranteed to be between 0.3-0.35MPa, and the pressure difference between the two sides is within ±0.01MPa.

[0011] During the annealing step, the interlocking of the cooling fans on the annealing line is removed, the maximum opening of the RJC variable frequency fan must not exceed 60%, and all FJC constant speed cooling fans are shut down.

[0012] In the drying step, the BS section does not use open flame heating, but adopts radiant heating.

[0013] In the winding step, the pinch rolls are opened after the strip head passes through them.

[0014] During the annealing step, the temperature of the strip steel exiting the annealing furnace and the rubber roller is below 60°C.

[0015] During the drying step, the drying temperature is controlled at 340-430℃ at a strip conveying speed of 60-100m / min.

[0016] In the drying step, the temperatures of sections DS1-3 are controlled at 340℃, 370℃, and 390℃, respectively.

[0017] During the cooling process, all constant-speed fans in the AJC cooling section are turned off, and only the variable-frequency fans are turned on to ensure that the temperature of the strip steel and rubber rollers exiting the cooling section is below 50°C.

[0018] Furthermore, the power of the variable frequency fan is controlled to be below 60% of its maximum power.

[0019] In the welding process, the welding current is 8000-9000A, the overlap is 2.5-3.5mm, the rolling pressure is 1200-1800kN, the welding force is 550-650kN, and the welding speed is 800-1200mm / min.

[0020] In the winding step, the silicon steel strip is wound onto the sleeve, and the finished coil weight does not exceed 10 tons.

[0021] The ultra-thin silicon steel with a thickness of less than 0.15 mm produced by the method according to the present invention has good quality.

[0022] When the rolled strip is coiled, the magnetic connection of the uncoiling belt causes it to wrinkle. The conventional method is to manually pull the belt head during coiling. Double-layer shears and welding shears also easily fail to cut the strip, and the conventional method is to manually cut it with electric shears. During welding, the strip is easily wrinkled when passing the No. 3 steering pinch roll. The conventional method is to open the automatic conveyor belt head to prevent wrinkling, while personnel assist in pulling at the double-layer shear platform. These operations are time-consuming and labor-intensive, and the weld quality is poor. To meet the requirements of automatic uncoiling, double-layer shearing, belt head conveying, and welding processes, this invention controls the strip thickness of the first and last 25-35m sections during rolling to between the target rolling thickness and +0.05-0.1mm. Even with conventional welding processes, the weld quality of this strip has been repeatedly verified to be satisfactory and meets the process requirements.

[0023] Ultra-thin strip steel with a thickness of 0.15mm or less is prone to deviation, wrinkling, or breakage during cleaning. In this invention, during the cleaning process, the squeeze rollers in the cleaning section are normally engaged, with the pressure on both sides of the squeeze rollers maintained between 0.3-0.35MPa and kept highly consistent, with a difference within ±0.01MPa. The brush rollers are not used. Otherwise, the strip steel is highly susceptible to deviation in the cleaning section or wrinkling due to speed differences in the squeeze rollers, leading to breakage. Tests were conducted with and without the squeeze rollers engaged, and with both squeeze rollers and brush rollers engaged. In both cases, deviation and wrinkling were observed on the operating side at point 5#CPC in the cleaning section, resulting in strip breakage.

[0024] Ultra-thin strip steel with a thickness of 0.15mm or less is easily blown and severely vibrated by cooling fans on the production line, such as RJC, FJC, and AJC fans. This vibration can easily cause the strip edges to tear or hit the equipment support frame, resulting in tearing and breakage. Therefore, this invention eliminates the interlocking of cooling fans on the production line. The power of the RJC variable frequency fan needs to be reduced, with the maximum opening not exceeding 60%. All FJC constant speed cooling fans are shut down to ensure that the temperature of the strip steel exiting the annealing furnace and the rubber rollers is below 60℃, which is sufficient to meet the strip steel cooling requirements. In the AJC cooling section after the coating drying furnace, all constant speed fans are also shut down, with only the variable frequency fan running, and the power controlled below 60%, to ensure that the temperature of the strip steel exiting the cooling section and the rubber rollers is below 50℃, which is sufficient to meet the strip steel cooling requirements.

[0025] The open flame section (BS) of the drying oven can easily burn the strip steel yellow, resulting in slight burn damage to the edges, which has a certain impact on the shape and product quality. Therefore, in this invention, the BS end of the drying oven cannot be heated with an open flame during production; only radiant heating is used, and the drying temperature is controlled at 340-430℃ at a strip steel conveying speed of 60-100m / min.

[0026] When the exit turning pinch roll is pressed down, the strip steel is easily squeezed and wrinkled. In order to prevent the strip steel from wrinkling, the present invention opens the pinch roll after the strip head passes the pinch roll during automatic winding.

[0027] During normal winding and unwinding, coil collapse can occur. Therefore, this invention winds the strip steel onto a sleeve during winding, and the finished coil weight should not exceed 10 tons to avoid coil collapse.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The method for producing ultra-thin silicon steel with a thickness of less than 0.15 mm on a continuous annealing coating line provided by this invention can successfully complete the continuous annealing coating production of ultra-thin silicon steel with a thickness of 0.15 mm and below. It solves the technical problems of uncoiling, welding, and shearing in the production of ultra-thin silicon steel with a thickness of 0.15 mm and below, effectively avoids production failures such as strip deviation, wrinkling, shaking and tearing during the production process, solves the smooth operation problem of mass production of ultra-thin silicon steel, and enables ordinary continuous annealing coating lines to also have the production capacity of ultra-thin silicon steel. Attached Figure Description

[0030] Figure 1This is a schematic diagram of the continuous annealing furnace and coating drying furnace. In the diagram, 01-inlet sealing chamber, 2-heating section (1RTF), 3-furnace throat 1 (1FTH), 4-soaking furnace (1SF), 5-isolated device 1 (1SEP), 6-heating section (2RTF), 7-furnace throat 2 (2FTH), 8-soaking furnace (2SF), 9-isolated device 2 (2SEP), 10-furnace throat 3 (3FTH), 11-tube cooling section (CTF), 12-furnace throat 4 (4FTH), 13-circulating gas jet cooling slow cooling section (SJC), 14-furnace throat 5 (5FTH), 15-circulating gas jet cooling fast cooling section (RJC), 16-outlet sealing chamber, 17-FJC, 18-drying furnace (DF-DS), 19-sintering furnace (DF-BS), 20-air jet cooling section (AJC);

[0031] Figure 2 The image shows the 0.10mm thick ultrathin silicon steel produced in Example 2;

[0032] Figure 3 The image shows the poor weld quality of the ultra-thin silicon steel in Comparative Example 1.

[0033] Figure 4 The image shows the ultra-thin silicon steel being wrinkled in Comparative Example 2.

[0034] Figure 5 The image shows the ultrathin silicon sample in Comparative Example 3 that has become misaligned and wrinkled.

[0035] Figure 6 Images showing the ultra-thin silicon steel in Comparative Example 4 undergoing edge scraping at AJC and edge scraping in the RJC furnace, resulting in strip breakage.

[0036] Figure 7 The image shows the collapse of the ultra-thin silicon steel strip after uncoiling in Comparative Example 6.

[0037] Figure 8 This is an image showing the collapse of the ultra-thin silicon steel in Comparative Example 7. Detailed Implementation

[0038] This invention provides a method for producing ultra-thin silicon steel with a thickness of less than 0.15 mm on a continuous annealing and coating line. The method includes the following steps: uncoiling → strip shearing → welding → cleaning → annealing → coating → drying → cooling → winding.

[0039] During rolling, the thickness of the strip at the beginning and end, 25-35m, is controlled between the target rolling thickness and 0.05-0.1mm, and then uncoiling, strip shearing, and welding are carried out.

[0040] During the cleaning step, the squeeze roller is put into normal use, and the pressure on both sides of the squeeze roller is guaranteed to be between 0.3-0.35MPa, and the pressure difference between the two sides is within ±0.01MPa.

[0041] During the annealing step, the interlocking of the cooling fans on the annealing line is removed, the maximum opening of the RJC variable frequency fan must not exceed 60%, and all FJC constant speed cooling fans are shut down.

[0042] In the drying step, the BS section does not use open flame heating, but adopts radiant heating.

[0043] In the winding step, the pinch rolls are opened after the strip head passes through them.

[0044] During the annealing step, the temperature of the strip steel exiting the annealing furnace and the rubber roller is below 60°C.

[0045] During the drying step, the drying temperature is controlled at 340-430℃ at a strip conveying speed of 60-100m / min.

[0046] In the drying step, the temperatures of sections DS1-3 are controlled at 340℃, 370℃, and 390℃, respectively.

[0047] During the cooling process, all constant-speed fans in the AJC cooling section are turned off, and only the variable-frequency fans are turned on to ensure that the temperature of the strip steel and rubber rollers exiting the cooling section is below 50°C.

[0048] Furthermore, the power of the variable frequency fan is controlled to be below 60% of its maximum power.

[0049] In the welding process, the welding current is 8000-9000A, the overlap is 2.5-3.5mm, the rolling pressure is 1200-1800kN, the welding force is 550-650kN, and the welding speed is 800-1200mm / min.

[0050] In the winding step, the silicon steel strip is wound onto the sleeve, and the finished coil weight does not exceed 10 tons.

[0051] The present invention will now be described in detail with reference to the embodiments.

[0052] Example 1

[0053] A method for producing 0.15 mm thick ultrathin silicon steel on a continuous annealing coating line, the method comprising the following steps: uncoiling → strip shearing → welding → cleaning → annealing → coating → drying → cooling → coiling;

[0054] During rolling, the thickness of the strip at the beginning and end of 30m is controlled at 0.2mm. Then, the strip is uncoiled, sheared at the beginning, and welded. During welding, the overlap is 0.15mm at 0.2mm, the welding current is 8600A, and the weld quality is normal.

[0055] During the cleaning process, the squeeze rollers were put into normal use, and the pressure on both sides of the squeeze rollers was adjusted to 0.3MPa. The strip steel in the cleaning section ran smoothly, and the strip steel exiting the cleaning section was normal.

[0056] During the annealing process, the blowing device from the cleaning section and the FJC constant speed cooling fan in the annealing furnace cooling section were all shut down, and the RJC variable frequency fan power was adjusted to 20%-55% of its opening. The strip steel operated normally, and the strip steel temperature exiting the annealing furnace was 34℃, which met the process requirements.

[0057] In the drying step, the BS open flame section of the drying oven is cut off, the DS radiant tube heating is turned on with 3 burners, the temperature of the drying oven is controlled at 410-430℃, and the quality of the plates coming out of the drying oven is normal.

[0058] In the cooling process, all constant-speed fans in the AJC cooling section were turned off, and four variable-frequency fans were turned on with their power set to 50%. The strip temperature exiting the cooling section was 42°C, which met the process requirements.

[0059] In the winding step, the steering pinch rollers are opened during exit winding, and the paper sleeve is installed on the winding machine. A large roll of 17.2 tons is divided into two smaller rolls for winding, with finished product weights of 8.9 tons and 8.3 tons respectively. After winding, the steel rolls are normal and no collapse occurs, successfully producing 0.15mm thick 15XWH1150 grade silicon steel.

[0060] Example 2

[0061] A method for producing 0.10 mm thick ultrathin silicon steel on a continuous annealing coating line, the method comprising the following steps: uncoiling → strip shearing → welding → cleaning → annealing → coating → drying → cooling → coiling;

[0062] During rolling, the thickness of the strip at the beginning and end of 30m is controlled between 0.15 and 0.17mm. Then, the strip is uncoiled, sheared at the beginning, and welded. During welding, the overlap is 0.15mm and 0.17mm. The welding current is 8200A and the weld quality is normal.

[0063] During the cleaning process, the squeeze rollers were put into normal use, and the pressure on both sides of the squeeze rollers was adjusted to 0.2MPa. The strip steel in the cleaning section ran smoothly, and the strip steel exiting the cleaning section was normal.

[0064] During the annealing process, the blowing device from the cleaning section and the FJC constant speed cooling fan in the annealing furnace cooling section were all shut down, and the RJC variable frequency fan power was adjusted to 20%-50% of its opening. The strip steel operated normally, and the strip steel temperature exiting the annealing furnace was 32℃, which met the process requirements.

[0065] In the drying step, the BS open flame section of the drying oven is cut off, two burners are turned on for DS radiant tube heating, the temperature of the drying oven is controlled at 400-420℃, and the quality of the plates coming out of the drying oven is normal.

[0066] In the cooling process, all constant-speed fans in the AJC cooling section were turned off, and three variable-frequency fans were turned on with a power setting of 45%. The strip temperature exiting the cooling section was 43°C, which met the process requirements.

[0067] In the winding step, the steering pinch rollers open during exit winding, the paper sleeve is installed on the winding machine, the finished product weight is 7.8 tons, the steel coil is normal after winding, no collapse occurs, and 0.10mm thick 10XWH1000 grade silicon steel is successfully produced. Figure 2 As shown.

[0068] Example 3

[0069] A method for producing 0.08 mm thick ultrathin silicon steel on a continuous annealing coating line, the method comprising the following steps: uncoiling → shearing with the strip head → welding → cleaning → annealing → coating → drying → cooling → winding;

[0070] During rolling, the thickness of the strip in the first and last 30m sections is controlled between 0.13 and 0.18mm. Then, the strip is uncoiled, sheared at the head, and welded. During welding, the overlap is 0.15mm and 0.16mm. The welding current is 8100A, and the weld quality is normal.

[0071] During the cleaning process, the squeeze rollers were put into normal use, and the pressure on both sides of the squeeze rollers was adjusted to 0.3MPa. The strip steel in the cleaning section ran smoothly, and the strip steel exiting the cleaning section was normal.

[0072] During the annealing process, the blowing device from the cleaning section and the FJC constant speed cooling fan in the annealing furnace cooling section are all shut down, and the RJC variable frequency fan power is adjusted to an opening of 15%-42%. The strip steel runs normally, and the strip steel temperature exiting the annealing furnace is 35℃, which meets the process requirements.

[0073] In the drying step, the BS open flame section of the drying oven is cut off, two burners are turned on for DS radiant tube heating, the temperature of the drying oven is controlled at 390-410℃, and the quality of the plates coming out of the drying oven is normal.

[0074] In the cooling process, all constant-speed fans in the AJC cooling section were turned off, and two variable-frequency fans were turned on with a power setting of 40%. The strip temperature exiting the cooling section was 41°C, which met the process requirements.

[0075] During the winding process, the steering pinch rollers are opened during exit winding, and the paper sleeve is installed on the winding machine. The finished product weighs 7.6 tons. After winding, the steel coil is normal and no collapse occurs. XST-080 grade silicon steel with a thickness of 0.08mm has been successfully produced.

[0076] Comparative Example 1

[0077] The process is the same as in Example 2, except that during rolling, the thickness of the strip is controlled to 0.10 mm at all points. Then, the strip is uncoiled, sheared at the ends, and welded. During welding, the overlap is 0.1 mm to 0.1 mm or 0.1 mm to 0.15 mm. However, regardless of the welding parameters, the replacement of the welding wheel, or the adjustment of the overlap, the weld quality is poor. Figure 3 As shown.

[0078] Comparative Example 2

[0079] The rest is the same as in Example 2, except that the pressure of the squeeze rollers was not finely adjusted during cleaning, and the pressure was in the range of 0.25-0.4 MPa. The pressure deviation on both sides of some squeeze rollers exceeded 0.05 MPa, causing the strip steel to wrinkle when producing 0.10 mm thick silicon steel. Figure 4 As shown.

[0080] Comparative Example 3

[0081] The rest is the same as in Example 3, except that during cleaning, all the squeezing rollers in the cleaning section are raised, causing the strip steel to deviate and become wrinkled in the cleaning tank. Figure 5 As shown.

[0082] Comparative Example 4

[0083] Everything else is the same as in Example 2, except that all cooling fans on the production line are in normal operation, the strip is scraped at the AJC point, and the strip breaks during scraping at the RJC furnace. Figure 6 As shown.

[0084] Comparative Example 5

[0085] The rest is the same as in Example 2, except that the open flame heating of the drying furnace was not cut off. The furnace temperature of the drying furnace was adjusted according to the normal process requirements. The surface of the strip steel turned yellow. Even when the furnace temperature of the drying furnace was adjusted between 350-520℃, the surface of the strip steel still showed different degrees of yellowing and could not be eliminated.

[0086] Comparative Example 6

[0087] The rest is the same as in Example 3, except that a paper sleeve was not used during winding, and the strip collapsed after unwinding, such as... Figure 7 As shown.

[0088] Comparative Example 7

[0089] The rest is the same as in Example 1, except that the coil was not split during winding; only a single 22-ton coil was wound. After unwinding and leaving for 2 hours, the strip began to slowly collapse. Figure 8 As shown.

[0090] The above detailed description of a method for producing ultra-thin silicon steel with a thickness of less than 0.15 mm on a continuous annealing coating line, with reference to the embodiments described above, is illustrative rather than limiting. Several embodiments may be listed within the defined scope. Therefore, variations and modifications that do not depart from the overall concept of the present invention should be within the protection scope of the present invention.

Claims

1. A method for producing ultra-thin silicon steel with a thickness of less than 0.15 mm on a continuous annealing and coating line, characterized in that, The method includes the following steps: uncoiling → shearing with the strip head → welding → cleaning → annealing → coating → drying → cooling → winding; During rolling, the thickness of the strip at the beginning and end, 25-35m, is controlled between the target rolling thickness and 0.05-0.1mm, and then uncoiling, strip shearing, and welding are carried out. During the cleaning step, the squeeze roller is put into normal use, and the pressure on both sides of the squeeze roller is guaranteed to be between 0.3-0.35MPa, and the pressure difference between the two sides is within ±0.01MPa. During the annealing step, the interlocking of the cooling fans on the annealing line is removed, the maximum opening of the variable frequency fan of the RJC rapid cooling section of the circulating gas jet cooling is not higher than 60%, and all the FJC constant speed cooling fans in the annealing furnace cooling section are shut down. In the drying step, the BS section of the sintering furnace does not use open flame heating, but adopts radiant heating. During the cooling process, all constant-speed fans in the air jet cooling section AJC are turned off, and only the variable frequency fans are turned on to ensure that the temperature of the strip and rubber rollers exiting the cooling section is below 50°C; the power of the variable frequency fans is controlled to be below 60% of their maximum power. In the winding step, the pinch rollers are opened after the strip head passes through them; the silicon steel strip is wound onto the sleeve, and the finished coil weight does not exceed 10 tons.

2. The method according to claim 1, characterized in that, During the annealing step, the temperature of the strip steel exiting the annealing furnace and the rubber roller is below 60°C.

3. The method according to claim 1, characterized in that, During the drying step, the drying temperature is controlled at 340-430℃ at a strip conveying speed of 60-100m / min.

4. The method according to claim 3, characterized in that, In the drying step, the temperatures of sections DS 1-3 of the drying oven are controlled at 340℃, 370℃, and 390℃, respectively.

5. The method according to claim 1, characterized in that, In the welding process, the welding current is 8000~9000A, the overlap is 2.5~3.5mm, the rolling pressure is 1200~1800kN, the welding force is 550~650kN, and the welding speed is 800~1200mm / min.

6. Ultrathin silicon steel with a thickness of less than 0.15 mm produced by the method according to any one of claims 1-5.

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