Continuous annealing furnace and continuous annealing method

Abstract

The invention discloses a continuous annealing furnace and a continuous annealing method, and solves the technical problem of poor generation of a magnesium silicate bottom layer in the prior art. The continuous annealing furnace comprises a furnace body; the humidifying pipe sets are located in the heating area and / or the soaking area of the furnace body, the number of the humidifying pipe sets is two, the two humidifying pipe sets are located above and below the strip steel respectively, and each humidifying pipe set comprises a plurality of humidifying pipes which are sequentially arranged in the running direction of the strip steel; wherein humidifying holes are formed in the two ends of the humidifying pipe, so that a medium containing water vapor and flowing through the humidifying pipe acts on the two sides of the strip steel in the width direction through the humidifying holes. According to the continuous annealing furnace, the reactivity of the strip steel head and the strip steel tail on the bottom layers on the two sides in the width direction is improved, a magnesium silicate bottom layer is formed, and a series of defects such as crystal exposure, thin bottom layer and chromatic aberration are avoided.

Description

Technical Field

[0001] The present application belongs to the technical field of continuous annealing furnaces, and specifically relates to a continuous annealing furnace and a continuous annealing method. Background Art

[0002] Oriented silicon steel is an important soft magnetic functional material for power construction. It is known as the "crown jewel" of the steel industry and is widely used in transformer manufacturing. During the manufacturing and use of transformers, oriented silicon steel is required to have "low iron loss, high magnetic induction, high-quality surface quality, and excellent plate shape". Oriented silicon steel usually undergoes steelmaking, continuous casting, hot rolling, normalizing, cold rolling, decarburization annealing, high-temperature annealing, hot stretching and flattening, finishing and packaging processes during the production process. Among them, the high-temperature annealing process is one of the key processes that affects the surface quality of oriented silicon steel products. The strip steel needs to be coiled into a steel coil and placed in a hood annealing furnace for high-temperature annealing.

[0003] At present, after high-temperature annealing, the edges of the outer and inner rings of oriented silicon steel at home and abroad have poor formation of magnesium silicate bottom layer in the width direction, resulting in a series of appearance defects such as exposed crystals, thin bottom layer, and color difference. Summary of the invention

[0004] In order to solve the current technical problem of poor formation of magnesium silicate bottom layer at the edges of the outer ring and inner ring in the width direction of oriented silicon steel, the present application provides a continuous annealing furnace and a continuous annealing method.

[0005] In a first aspect of the present application, a continuous annealing furnace is provided, comprising:

[0006] Furnace body;

[0007] A humidifying pipe group is located in the heating zone and / or the soaking zone of the furnace body. Two humidifying pipe groups are provided. The two humidifying pipe groups are respectively located above and below the steel strip. The humidifying pipe group includes a plurality of humidifying pipes arranged in sequence along the running direction of the steel strip.

[0008] Wherein, humidification holes are provided at both ends of the humidification tube, so that the medium containing water vapor flowing through the humidification tube acts on both sides of the strip in the width direction through the humidification holes.

[0009] In some embodiments, the humidifying pipe includes a middle section and two humidifying sections, the two humidifying sections are connected to two ends of the middle section, and the humidifying section is provided with a plurality of humidifying holes arranged in sequence along the width direction of the steel strip.

[0010] In some embodiments, the humidifying section is provided with a first end and a second end relative to each other, the first end extends beyond the edge of the strip in the width direction, the second end is connected to the middle section, and along the axial direction of the humidifying tube, the distance between the second end and the edge of the strip in the width direction is 50 mm to 250 mm.

[0011] In some embodiments, along the medium flow direction, the diameters of the humidification holes of the humidification tube increase sequentially.

[0012] In some embodiments, the humidification tube is provided with a thermal insulation layer, and the thermal insulation layer is coated on the middle section.

[0013] In some embodiments, it also includes two ventilation pipe groups respectively located above and below the strip, and the ventilation pipe group and the humidification pipe group are arranged in sequence along the direction close to the strip. The ventilation pipe group includes a plurality of ventilation pipes arranged in sequence along the running direction of the strip, and the ventilation pipe is provided with a plurality of ventilation holes. Along the running direction of the strip, the ventilation pipe and the humidification pipe are staggered.

[0014] In some embodiments, the diameter of the humidification tube is smaller than the diameter of the ventilation tube; the diameter of the humidification tube is 5 mm to 20 mm; the diameter of the ventilation tube is 10 mm to 40 mm.

[0015] In some embodiments, the diameter of the ventilation hole is larger than the diameter of the humidification hole; the diameter of the ventilation hole is 5mm to 20mm, the diameter of the humidification hole is 2mm to 10mm, the spacing between adjacent humidification holes is not less than 5mm, and not greater than three times the circular diameter of the medium sprayed onto the surface of the strip through the humidification hole.

[0016] In a second aspect of the present application, a continuous annealing method is provided, which is applicable to the continuous annealing furnace of the first aspect, and the continuous annealing method comprises the following steps:

[0017] The strip runs in the furnace for continuous annealing;

[0018] When the strip head of the steel strip passes through the heating zone and / or the soaking zone, a medium containing water vapor is introduced into the humidifying tubes of the humidifying tube group so that the medium acts on both sides of the strip in the width direction;

[0019] When the middle part of the steel strip passes through the heating zone and / or the soaking zone, stop introducing the medium containing water vapor into the humidifying pipe of the humidifying pipe group;

[0020] When the tail of the steel strip passes through the heating zone and / or the equalizing zone, a medium containing water vapor is introduced into the humidifying tubes of the humidifying tube group so that the medium acts on both sides of the steel strip in the width direction.

[0021] In some embodiments, the dew point of the medium is 50°C to 80°C, and the flow rate of the medium is 50m 3 / h~100m 3 / h.

[0022] The continuous annealing furnace provided according to the embodiment of the present application includes a furnace body and a humidifying tube group, the humidifying tube group can provide a water vapor atmosphere for the strip steel, the humidifying tube group is located in the heating zone and / or the soaking zone of the furnace body, in this area, the water vapor can react with the Fe and Si on the surface of the strip steel to generate iron oxides, so that the water vapor reacts with the Fe and Si on the surface of the strip steel to generate iron oxides, and in the high-temperature annealing process, the iron oxides can react with the hydrogen in the atmosphere to form water vapor, supplement the oxidizing atmosphere between the steel coil layers, improve the reactivity of the local bottom layer, and form a magnesium silicate bottom layer. There are two humidifying tube groups, and the two humidifying tube groups are respectively located above and below the strip steel, so that the upper surface and the lower surface of the strip steel can form iron oxides, and the humidifying tube group includes a plurality of humidifying tubes arranged in sequence along the running direction of the strip steel, so as to extend the action time of the strip steel and the water vapor during the running process of the strip steel, increase the generation of iron oxides on the surface of the strip steel, so as to react with hydrogen in the high-temperature annealing process to form water vapor, supplement the interlayer oxidizing atmosphere, improve the reactivity of the bottom layer of the strip steel, and form a magnesium silicate bottom layer.

[0023] Both ends of the humidifying tube are provided with humidifying holes so that the medium containing water vapor flowing through the humidifying tube acts on both sides of the strip in the width direction through the humidifying holes, thereby increasing the amount of iron-based oxides generated on both sides of the strip in the width direction, that is, the amount of iron-based oxides generated on both sides of the strip in the width direction is higher than that in the middle part. Even if the head and tail of the strip are deformed on both sides in the width direction, resulting in a large interlayer gap and a fast water loss rate, there are still iron-based oxides that react with hydrogen to form water vapor to supplement the interlayer oxidation atmosphere, thereby increasing the reactivity of the bottom layer of the local strip (the head and tail on both sides in the width direction), forming a magnesium silicate bottom layer, and avoiding a series of defects such as exposed crystals, thin bottom layer, and color difference. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A schematic structural diagram of a continuous annealing furnace in one or more embodiments of the present application is shown.

[0025] Figure 2 The assembly diagram of the furnace body, the humidification tube group and the ventilation tube group is shown.

[0026] Figure 3 Another angled assembly view of the furnace body, the humidification tube assembly, and the ventilation tube assembly is shown.

[0027] Figure 4 An assembly diagram of the humidification tube and insulation layer is shown.

[0028] Figure 5 Shows Figure 4 sectional view of .

[0029] Figure 6 A schematic diagram of the structure of the ventilation tube is shown.

[0030] Description of reference numerals:

[0031] 10-furnace body, 11-heating zone, 12-heating zone, 13-nitriding zone, 14-cooling zone, 15-inlet, 16-outlet.

[0032] 20 - humidification tube group, 21 - humidification tube, 211 - humidification section, 212 - humidification hole, 23 - insulation layer.

[0033] 30-ventilation tube group, 31-ventilation tube, 312-ventilation hole.

[0034] 50-Strip steel.

[0035] 60-Cross the steel wire. DETAILED DESCRIPTION

[0036] In order to make the technical personnel in the technical field to which the present application belongs to understand the present application more clearly, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0037] During the high-temperature annealing process, oriented silicon steel is processed in the furnace in the form of steel coils and is heated unevenly. Therefore, the thermal expansion at each position is uneven, and the deformation of the steel coil is uneven. The edges of the outer and inner rings of the steel coils in the width direction are the most deformed areas, which makes the gap between the strip steel layers of the steel coil in this area larger, and the water loss rate is faster during high-temperature annealing, and the oxidizability between layers is reduced, resulting in poor formation of the magnesium silicate bottom layer, resulting in a series of defects caused by poor bottom layer reaction, such as exposed crystals, thin bottom layer, and color difference.

[0038] It should be noted that generally, silicon steel is formed into a cold-rolled coil after cold rolling, and then the cold-rolled coil is unrolled and continuously annealed, and then it is coiled into a continuous annealing coil and placed in a furnace for high-temperature annealing. Therefore, the head of the strip in this application refers to the head of the cold-rolled coil, and the tail of the strip refers to the tail of the cold-rolled coil. After the cold-rolled coil is continuously annealed, the head will form the inner ring of the continuous annealing coil, and the tail will form the inner ring of the continuous annealing coil. It can be seen that the head of the strip corresponds to the inner ring of the continuous annealing coil, and the tail of the strip corresponds to the outer ring of the continuous annealing coil.

[0039] The first aspect of the present application provides a continuous annealing furnace, which can increase the moisture content of the head and tail edges of the strip during the decarburization annealing of oriented silicon steel, thereby improving the uniformity of the magnesium silicate bottom layer of the oriented silicon steel after high-temperature annealing, and avoiding defects such as exposed crystals, thin bottom layer, and color difference.

[0040] See also Figure 1 as well as Figure 2 The continuous annealing furnace provided in the present application includes a furnace body 10 and a humidifying tube group 20, wherein:

[0041] The furnace body 10 provides a decarburization annealing function for the steel strip 50 . Generally speaking, the furnace body 10 includes a heating zone 11 , a soaking zone 12 , a nitriding zone 13 and a cooling zone 14 which are sequentially arranged along the running direction of the steel strip 50 . The steel strip 50 runs along the steel passing line 60 of the furnace body 10 .

[0042] The humidifying tube group 20 can provide a water vapor atmosphere for the steel strip 50, so that the water vapor reacts with Fe and Si on the surface of the steel strip 50 to generate iron oxides. In the high-temperature annealing process, the iron oxides can react with hydrogen in the atmosphere to form water vapor, replenish the oxidizing atmosphere between the steel coil layers, improve the reactivity of the local bottom layer, and form a magnesium silicate bottom layer. The humidifying tube group 20 is located in the heating zone 11 and / or the soaking zone 12 of the furnace body 10. The furnace temperature of the heating zone 11 and the soaking zone 12 is 750°C to 900°C. The humidifying tube group 20 is located at a position in the continuous annealing furnace where the furnace temperature is 750°C to 900°C. At this temperature, the water vapor can react with Fe and Si on the surface of the steel strip 50 to generate iron oxides. If the humidifying tube group 20 is located in other areas of the furnace body 10, the furnace temperature may be lower than 750°C or higher than 900°C. If the furnace temperature is lower than 750°C, this will reduce the generation rate of the iron oxides to a certain extent. If the furnace temperature is higher than 900°C, this will deteriorate the magnetic properties of the oriented silicon steel to a certain extent. There are two humidifying tube groups 20, which are respectively located above and below the steel strip 50, so that iron-based oxides can be formed on the upper surface and the lower surface of the steel strip 50. The humidifying tube group 20 includes a plurality of humidifying tubes 21 arranged in sequence along the running direction of the steel strip 50, such as three, five or ten, so as to extend the action time between the steel strip 50 and water vapor during the running process of the steel strip 50, increase the generation of iron-based oxides on the surface of the steel strip 50, react with hydrogen to form water vapor in the high-temperature annealing process, supplement the interlayer oxidizing atmosphere, improve the reactivity of the bottom layer of the steel strip 50, and form a magnesium silicate bottom layer.

[0043] Among them, humidifying holes 212 are provided at both ends of the humidifying tube 21, and the humidifying holes 212 face the strip 50, so that the medium containing water vapor flowing through the humidifying tube 21 acts on the two sides of the width direction of the strip 50 through the humidifying holes 212, thereby increasing the amount of iron-based oxides generated on both sides of the width direction of the strip 50, that is, the amount of iron-based oxides generated on both sides of the width direction of the strip 50 is higher than that of the middle part. Even if the head and the tail of the strip 50 are deformed on both sides in the width direction, resulting in a large interlayer gap and a fast water loss rate, there are still iron-based oxides that react with hydrogen to form water vapor to supplement the interlayer oxidation atmosphere, thereby improving the reactivity of the bottom layer of the local strip 50 (the head and the tail on both sides in the width direction), forming a magnesium silicate bottom layer, and avoiding the formation of a series of defects such as exposed crystals, thin bottom layer, and color difference.

[0044] Generally speaking, the humidifying pipe 21 extends along the width direction of the steel strip 50. In some embodiments, the humidifying pipe 21 includes a middle section and two humidifying sections 211. The two humidifying sections 211 are connected to the two ends of the middle section. The humidifying section 211 is provided with a plurality of humidifying holes 212 arranged in sequence along the width direction of the steel strip 50. That is to say, the two ends of the humidifying tank are respectively provided with a plurality of humidifying holes 212, such as two, three or five humidifying holes 212, to improve the humidification effect on both sides of the steel strip 50 in the width direction and to improve the uniformity of the iron oxides at the edge of the steel strip 50. In other embodiments, the humidifying section 211 may also be provided with a humidifying hole 212, the shape of the humidifying hole 212 is a waist-shaped hole, the length direction of the waist-shaped hole is parallel to the axial direction of the humidifying pipe 21, and the humidification effect on both sides of the steel strip 50 in the width direction can also be achieved, and the generation amount of iron oxides can be increased.

[0045] In some embodiments, the humidifying section 211 is provided with a first end and a second end relative to each other, the first end extending beyond the edge of the steel strip 50 in the width direction, and the second end connected to the middle section, that is, both ends of the humidifying tube 21 extend out of the steel strip 50, and along the axial direction of the humidifying tube 21, the spacing between the second end and the edge of the steel strip 50 in the width direction is 50mm to 250mm, that is, the humidifying holes 212 are distributed outside the steel strip 50 within a spacing range of 50mm to 250mm from the edge of the steel strip 50 toward the center line, so as to humidify the positions where dew crystals, thin bottom layer, and color difference appear, increase the generation amount of iron-based oxides at the position, thereby increasing the reactivity of the bottom layer at the position, and avoiding the formation of a series of defects such as dew crystals, thin bottom layer, and color difference. Specifically, the distance between the second end and the edge of the steel strip 50 along the width direction may be 55 mm, 58 mm, 60 mm, 70 mm, 80 mm, 90 mm, 100 mm, 110 mm, 120 mm, 130 mm, 140 mm, 150 mm, 160 mm, 170 mm, 180 mm, 200 mm, 210 mm, 220 mm, 230 mm or 240 mm, etc. In other embodiments, the distance between the second end and the edge of the steel strip 50 along the width direction may also be 300 mm, 350 mm, etc., which can still increase the generation amount of iron oxides on both sides of the steel strip 50 along the width direction.

[0046] One end of the humidifying tube 21 is connected to the gas source, and the other end is closed. In some embodiments, the diameter of the humidifying holes 212 of the humidifying tube 21 increases in sequence along the medium flow direction, that is, the humidifying holes 212 on the side close to the gas source have a smaller aperture, and the humidifying holes 212 on the side away from the gas source have a larger aperture, so as to balance the medium pressure of each humidifying hole 212 and ensure the uniformity of the magnesium silicate bottom layer on both sides of the strip steel 50 along the width direction. In other embodiments, the apertures of the humidifying holes 212 of the humidifying tube 21 can also be the same, which can still increase the amount of iron oxides generated on both sides of the strip steel 50 along the width direction and improve the uniformity of the magnesium silicate bottom layer.

[0047] In some embodiments, the humidifying tube 21 is provided with an insulation layer 23, and the insulation layer 23 is coated on the middle section to improve the uniformity of the airflow in the humidifying tube 21, so as to ensure the uniformity of the magnesium silicate bottom layer on both sides of the strip 50 along the width direction. The insulation layer 23 can be obtained by wrapping the refractory wool on the body of the humidifying tube 21, and the thickness of the insulation layer 23 can be 5mm to 15mm. The maximum length of the insulation layer 23 along the axial direction of the humidifying tube 21 can be the width of the annealing furnace minus twice the length of the humidifying section 211. In another embodiment, the humidifying tube 21 is not provided with an insulation layer 23. Although the temperature of the medium close to the gas source side is lower and the temperature of the medium far from the gas source side is higher, so that the water vapor content in the medium close to the gas source side is higher and the water vapor content in the medium far from the gas source side is lower, the generation amount of iron oxides on both sides of the width direction of the strip 50 can still be increased.

[0048] In some embodiments, the continuous annealing furnace further includes two ventilation pipe groups 30 respectively located above and below the steel strip 50. The ventilation pipe group 30 and the humidification pipe group 20 are arranged in sequence in the direction close to the steel strip 50, that is, the ventilation pipe 31 is far away from the steel strip 50, and the humidification pipe 21 is closer to the steel strip 50, which is more convenient for local humidification of the steel strip 50 and increases the generation of iron oxides on both sides of the width direction of the steel strip 50. In a specific implementation, in the vertical direction, the spacing between the humidification pipe 21 and the ventilation pipe 31 can be greater than (d3+d4) / 2, wherein d3 is the diameter of the circle formed by the medium introduced into the ventilation hole 312 and sprayed onto the surface of the steel strip 50, and d4 is the diameter of the circle formed by the medium introduced into the humidification hole 212 and sprayed onto the surface of the steel strip 50. Controlling the spacing between the humidification pipe 21 and the ventilation pipe 31 in the vertical direction can prevent the medium sprayed from the ventilation hole 312 of the ventilation pipe 31 from being blocked by the humidification pipe 21, so as to ensure the humidification effect.

[0049] The ventilation pipe group 30 includes a plurality of ventilation pipes 31 arranged in sequence along the running direction of the steel strip 50. The ventilation pipe 31 is provided with a plurality of ventilation holes 312 arranged in sequence along the axial direction of the ventilation pipe 31. The plurality of ventilation holes 312 can be evenly distributed to provide a protective atmosphere in the continuous annealing furnace through the ventilation holes 312. The protective atmosphere can be a gas mixture that is the same as the medium flowing through the humidifying pipe 21, for example, the gas mixture includes nitrogen, hydrogen and water vapor, and can also form a uniform iron oxide in the width direction of the steel strip 50. Along the running direction of the steel strip 50, the ventilation pipe 31 and the humidifying pipe 21 are staggered to avoid interference between the gas ejected from the ventilation holes 312 of the ventilation pipe 31 and the humidifying pipe 21.

[0050] Since the ventilation volume of the humidifying tube 21 is smaller than that of the ventilation tube 31, the diameter of the humidifying tube 21 can be smaller than the diameter of the ventilation tube 31, which saves space and meets the ventilation requirements. Of course, the diameter of the humidifying tube 21 can also be larger than the diameter of the ventilation tube 31, which can also meet the ventilation requirements. In a specific implementation, the diameter of the humidifying tube 21 can be 5mm to 20mm, such as 7mm, 9mm, 10mm, 12mm, 15mm, 17mm or 18mm. The diameter of the ventilation tube 31 can be 10mm to 40mm, such as 11mm, 14mm, 15mm, 20mm, 25mm, 27mm, 30mm, 35mm, 37mm, or 38mm.

[0051] Similarly, based on the fact that the gas flow rate of the humidifying hole 212 is less than the ventilation volume of the vent pipe 31, in some embodiments, the diameter of the vent hole 312 may be greater than the diameter of the humidifying hole 212. Of course, in other embodiments, the diameter of the venting air may also be less than or equal to the diameter of the humidifying hole 212. In a specific implementation, the diameter of the vent hole 312 may be 5 mm to 20 mm, such as 7 mm, 9 mm, 10 mm, 12 mm, 15 mm, 17 mm or 18 mm. The diameter of the humidifying hole 212 may be 2 mm to 10 mm, such as 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm or 9 mm. Among them, the spacing between adjacent humidifying holes 212 may be not less than 5 mm, and not more than three times the diameter of the circle presented by the medium sprayed onto the surface of the strip steel 50 through the humidifying hole 212.

[0052] In some embodiments, the continuous annealing furnace also includes a gas source, a first stop valve and a second stop valve. The gas source is connected to all humidification tubes through a first main pipe to provide a medium to all humidification tubes. The first stop valve is installed on the first main pipe to cut off or connect the first main pipe. The gas source is connected to all ventilation tubes 31 through a second main pipe to provide a medium to all ventilation tubes 31. The second stop valve is installed on the second main pipe to cut off or connect the second main pipe. When the first main pipe is connected, the medium in the gas source can enter all humidification tubes. When the first main pipe is cut off, the medium cannot enter the humidification tube 21. When the second main pipe is connected, the medium in the gas source can enter all ventilation tubes 31. When the second main pipe is cut off, the medium cannot enter the ventilation tube 31.

[0053] In some embodiments, the continuous annealing furnace further includes a controller, the first stop valve and the second stop valve are both electrically controlled valves, the controller is electrically connected to the two electrically controlled valves, and the controller controls the opening or closing of the first electrically controlled valve and the second electrically controlled valve to conduct or cut off the first main pipe and the second main pipe. The controller can obtain the number of rotations of the annealing roller of the continuous annealing furnace to calculate when the head and tail of the strip 50 run to the humidification pipe group 20, thereby controlling the opening or closing of the first stop valve. In other embodiments, the opening and closing of the stop valve can also be judged and controlled by manual operation, and the circulation or cutoff of the medium in the humidification pipe can also be achieved.

[0054] The second aspect of the present application provides a continuous annealing method, which is applicable to the continuous annealing furnace of any embodiment of the first aspect.

[0055] The continuous annealing method provided in the present application can form thicker iron-based oxides on both sides of the width direction of the strip head and the strip tail of the oriented silicon steel, so that in the subsequent high-temperature annealing, a magnesium silicate bottom layer with uniform thickness is formed at the head and tail of the strip 50 along the width direction, avoiding defects such as exposed crystals, thin bottom layer, and color difference.

[0056] The continuous annealing method of the present application comprises the following steps:

[0057] S1. The steel strip 50 runs in the furnace body 10 for continuous annealing.

[0058] The steel strip 50 enters the furnace body 10 from the inlet 15 and exits from the outlet 16 . During the operation in the furnace body 10 , the steel strip 50 is heated, soaked, nitrided and cooled to complete continuous annealing.

[0059] S2. When the strip head of the steel strip 50 passes through the heating zone 11 and / or the soaking zone 12, a medium containing water vapor is introduced into the humidifying tube 21 of the humidifying tube group 20 so that the medium acts on both sides of the steel strip 50 in the width direction;

[0060] The head of the strip 50 is the position where the defect occurs, and its length is 500m to 1000m from the head of the strip 50, and is also 500m to 1000m from the end of the inner ring of the high-temperature annealed steel coil. In this process, the controller controls the first stop valve to open and conduct the main pipe to pass the medium containing water vapor into the humidification pipe 21 of the humidification pipe group 20.

[0061] S3, when the middle portion of the steel strip 50 passes through the heating zone 11 and / or the soaking zone 12, stop introducing the medium containing water vapor into the humidifying tube 21 of the humidifying tube group 20;

[0062] The middle area of ​​the steel strip 50 is located in the middle of the steel coil during the high temperature annealing process, is not easily deformed, has a good interlayer oxidation atmosphere, and is not prone to a series of appearance defects such as crystal exposure, thin bottom layer, and color difference. Therefore, when the middle of the steel strip 50 passes through this area, no additional humidification is required. In this process, the controller controls the first stop valve to close and the main pipe to stop the medium containing water vapor from being passed into the humidification pipe 21 of the humidification pipe group 20.

[0063] S4. When the tail of the steel strip 50 passes through the heating zone 11 and / or the equalizing zone 12, a medium containing water vapor is introduced into the humidifying pipe 21 of the humidifying pipe group 20 so that the medium acts on both sides of the steel strip 50 in the width direction.

[0064] The tail of the strip 50 is also the location where the defect occurs, and its length is 500m to 2000m from the tail of the strip 50, and is also 500m to 2000m from the end of the outer ring of the high-temperature annealed steel coil. In this process, the controller controls the first stop valve to open and conduct the main pipe to pass the medium containing water vapor into the humidification pipe 21 of the humidification pipe group 20.

[0065] It should be noted that when the steel strip 50 is running in the continuous annealing furnace, the medium is continuously introduced into the ventilation pipe group 30 to form a protective atmosphere.

[0066] In some embodiments, the dew point of the medium is 50°C to 80°C, indicating the content of water vapor in the medium. The higher the dew point, the higher the water vapor content in the medium. If the dew point of the medium is too low, the amount of iron oxides generated at the edge of the strip 50 in the width direction will be reduced to a certain extent, thereby affecting the improvement effect of appearance defects. If the dew point of the medium is too high, the amount of iron oxides generated at the edge of the strip 50 in the width direction will no longer increase. In other embodiments, the dew point of the medium can also be 85°C, which can also increase the amount of iron oxides generated at the edge of the strip 50 in the width direction.

[0067] In some embodiments, the flow rate of the medium flowing through the humidification tube group 20 can be 50m 3 / h~100m 3 / h, that is to say, the total flow rate of the medium in all humidification pipes 21 is 50m 3 / h~100m 3 / h, 50m 3 / h~100m 3 The medium flow rate of the ventilation pipe group 30 can be 100m / h, which matches the size of the humidification pipe 21 and the humidification hole 212 to ensure the humidification effect. 3 / h~400m 3 / h, that is to say, the total flow rate of the medium in all ventilation pipes 31 is 100m 3 / h~400m3 / h.

[0068] The medium contains not only water vapor but also hydrogen and nitrogen, and the content of hydrogen can be 50% to 80%.

[0069] The continuous annealing method is further described below in conjunction with specific embodiments.

[0070] In test groups 1 to 5, the continuous annealing furnace and the continuous annealing method provided in the present application were used for manufacturing, and the specific parameters are shown in Table 1.

[0071] Table 1

[0072] Comparison group 1 to comparison group 5

[0073] Comparative Groups 1 to 5 were annealed in a continuous annealing furnace, wherein in Comparative Group 1, the annealing furnace was not provided with a humidifying tube group 20; and in Comparative Groups 2 to 5, the annealing furnace was provided with a humidifying tube group 20. The specific process parameters of Comparative Groups 1 to 5 are shown in Table 2.

[0074] Table 2

[0075] The oriented silicon steel sheets obtained in the above test group and comparison group were subjected to high temperature annealing and stretching flattening, and their surface quality was evaluated. There were appearance defects on both sides of the strip head and tail along the width direction. The length and width dimensions of the defects are shown in Table 3.

[0076] From the data in Table 3, it can be seen that the continuous annealing method of the continuous annealing furnace of test group 1 to test group 5 has appearance defects on both sides of the outer ring along the width direction, the length of the defect on the upper side is 50-200m, the width is 30-60mm, and the length of the defect on the lower side is 45-180m, and the width is 25-50mm. The inner ring has appearance defects on both sides along the width direction, the length of the defect on the upper side is 45-150m, the width is 25-50mm, and the length of the defect on the lower side is 40-135m, and the width is 20-45mm.

[0077] The continuous annealing furnace and continuous annealing method provided by the present application have at least the following advantages:

[0078] (1) By providing the humidifying tube group 20, the two sides of the width direction of the head and tail of the steel strip 50 are humidified, and the water vapor concentration on both sides of the width direction of the steel strip 50 is increased, which can effectively promote the formation of more iron-based oxides at the edge, so as to supplement the problem of low interlayer oxidation on both sides of the width direction of the outer ring and the inner ring of the steel coil during the high-temperature annealing process, improve the reactivity of the local bottom layer, promote the formation of high-quality magnesium silicate bottom layer, and solve the defects of crystal exposure, color difference and thin bottom layer caused by poor bottom layer reaction at the edge.

[0079] (2) The humidifying tube group 20 is disposed in the 750°C to 900°C region of the continuous annealing furnace, where the generation rate of iron-based oxides is fast and the efficiency is high.

[0080] (3) The humidifying pipe 21 and the ventilation pipe 31 can be controlled separately by the first stop valve and the second stop valve. The first stop valve is opened at the position where defects are likely to occur at the head and tail of the steel strip 50, so as to increase the proportion of local iron oxides in the steel strip 50, thereby avoiding other adverse effects on the entire steel strip 50. The operation is simple, the process is convenient, the cost is low, the effect is significant, and other adverse factors affecting the surface quality of the steel strip 50 will not be introduced.

[0081] (4) The present invention can significantly improve various defects on the surface edge of oriented silicon steel, improve the surface qualification rate of oriented silicon steel, and increase economic benefits.

[0082] In the present application, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0083] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise" and "counterclockwise" indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0084] In this application, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0085] In addition, the descriptions of "first", "second", etc. in this application are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include one or more features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0086] Although the embodiments of the present application have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the claims and their equivalents.

Claims

1. A continuous annealing furnace, characterized in that: include: Furnace body; A humidifying pipe group is located in the heating zone and / or the soaking zone of the furnace body. Two humidifying pipe groups are provided. The two humidifying pipe groups are respectively located above and below the steel strip. The humidifying pipe group includes a plurality of humidifying pipes arranged in sequence along the running direction of the steel strip. Wherein, humidification holes are provided at both ends of the humidification tube, so that the medium containing water vapor flowing through the humidification tube acts on both sides of the strip in the width direction through the humidification holes.

2. The continuous annealing furnace according to claim 1, characterized in that: The humidifying pipe comprises a middle section and two humidifying sections. The two humidifying sections are connected to two ends of the middle section. The humidifying section is provided with a plurality of humidifying holes arranged in sequence along the width direction of the steel strip.

3. The continuous annealing furnace according to claim 2, characterized in that: The humidifying section is provided with a first end and a second end opposite to each other, the first end extends beyond the edge of the strip in the width direction, the second end is connected to the middle section, and along the axial direction of the humidifying tube, the distance between the second end and the edge of the strip in the width direction is 50 mm to 250 mm.

4. The continuous annealing furnace according to claim 1, characterized in that: Along the medium flow direction, the diameters of the humidification holes of the humidification tube increase successively.

5. The continuous annealing furnace according to any one of claims 2 to 4, characterized in that: The humidifying tube is provided with a heat-insulating layer, and the heat-insulating layer is coated on the middle section.

6. The continuous annealing furnace according to any one of claims 1 to 4, characterized in that: It also includes two ventilation pipe groups respectively located above and below the strip steel. The ventilation pipe group and the humidification pipe group are arranged in sequence along the direction close to the strip steel. The ventilation pipe group includes a plurality of ventilation pipes arranged in sequence along the running direction of the strip steel. The ventilation pipe is provided with a plurality of ventilation holes. Along the running direction of the strip steel, the ventilation pipe and the humidification pipe are staggered.

7. The continuous annealing furnace according to claim 6, characterized in that: The diameter of the humidifying tube is smaller than the diameter of the ventilation tube; the diameter of the humidifying tube is 5 mm to 20 mm; the diameter of the ventilation tube is 10 mm to 40 mm.

8. The continuous annealing furnace according to claim 6, characterized in that: The diameter of the ventilation hole is larger than the diameter of the humidifying hole; the diameter of the ventilation hole is 5mm to 20mm, the diameter of the humidifying hole is 2mm to 10mm, the spacing between adjacent humidifying holes is not less than 5mm, and is not greater than three times the circular diameter of the medium sprayed onto the surface of the strip through the humidifying hole.

9. A continuous annealing method, applicable to the continuous annealing furnace according to any one of claims 1 to 8, characterized in that: The continuous annealing method comprises the following steps: The strip runs in the furnace for continuous annealing; When the strip head of the steel strip passes through the heating zone and / or the soaking zone, a medium containing water vapor is introduced into the humidifying tubes of the humidifying tube group so that the medium acts on both sides of the strip in the width direction; When the middle part of the steel strip passes through the heating zone and / or the soaking zone, stop introducing the medium containing water vapor into the humidifying pipe of the humidifying pipe group; When the tail of the steel strip passes through the heating zone and / or the equalizing zone, a medium containing water vapor is introduced into the humidifying tubes of the humidifying tube group so that the medium acts on both sides of the steel strip in the width direction.

10. The continuous annealing method according to claim 9, characterized in that: The dew point of the medium is 50°C to 80°C, and the flow rate of the medium is 50m 3 / h~100m 3 / h.

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