Annealing test furnace for silicon steel sheet and process method of annealing test furnace

Abstract

The invention belongs to the technical field of silicon steel sheet annealing test furnaces, belongs to environment-friendly manufacturing planning of ultrahigh-grade oriented silicon steel, and particularly discloses a silicon steel sheet annealing test furnace and a process method thereof. The silicon steel sheet annealing test furnace comprises an inlet section, a heating section, a connecting section and an outlet section, and the inlet section, the heating section, the connecting section and the outlet section form a furnace body structure; the furnace body structure is fixedly installed on a floor in a workshop through two H-shaped steel, the furnace body structure is provided with three cooling air discharging pipes, and the cooling air discharging pipes are outwards led out of the workshop for discharging. According to the silicon steel sheet annealing test furnace and the process method thereof, the three independent heating sections I, II and III and the three independent connecting sections I, II and III are arranged, and are matched with the independent online oxygen analyzer, the sampling port and the atmosphere supply system; and the requirements of multiple scenes such as an intermediate annealing scene, a non-oriented silicon steel finished product annealing scene and oriented silicon steel high-temperature annealing can be met.

Description

Technical Field

[0001] This invention relates to the field of silicon steel sheet annealing furnace technology, specifically to a silicon steel sheet annealing test furnace and its process method, belonging to the field of green manufacturing of ultra-high grade oriented silicon steel. Background Technology

[0002] Silicon steel is the core magnetic material for electrical equipment such as motors and transformers. Therefore, its magnetic properties, surface quality and structural consistency directly determine the energy efficiency and service life of the end products. The annealing process of silicon steel processing is a key link to optimize the performance of silicon steel.

[0003] Existing equipment is mostly designed for specific types of silicon steel, making it difficult to meet the different process requirements such as intermediate annealing and finished annealing of oriented silicon steel. In addition, most equipment adopts a uniform power regulation mode and lacks a segmented independent temperature control mechanism, making it difficult to adapt to the annealing needs of silicon steel of different specifications. Summary of the Invention

[0004] The purpose of this invention is to provide a silicon steel sheet annealing test furnace and its process method, so as to solve the problem mentioned in the background art that the existing equipment is difficult to adapt to the annealing requirements of silicon steel of different specifications.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a test furnace for annealing silicon steel sheets and its process, comprising an inlet section, a heating section, a connecting section, and an outlet section, wherein the inlet section, heating section, connecting section, and outlet section constitute the furnace body structure, the furnace body structure is fixedly installed on the floor of the workshop by two H-beams, and the furnace body structure is provided with three cooling air exhaust pipes, which are led out of the factory building for exhaust; The heating section is provided with three sections, namely heating section one, heating section two, and heating section three; the connecting section is provided with three sections, namely connecting section one, connecting section two, and connecting section three; connecting section three and the outlet section form a whole; the inlet section, connecting section one, connecting section two, and connecting section three and the outlet section are each provided with independent gas collection hoods and exhaust pipes, and the exhaust pipes are led out of the plant for discharge; Preferably, a heating section one is provided on one side of the inlet section, a heating section two is provided on the side of the heating section one away from the heating section one, a connecting section one is provided on the other side of the heating section two, a heating section three is provided on the other side of the connecting section one, a connecting section two is provided on the other side of the heating section three, the connecting section two is connected to the connecting section three, and the connecting section three and the outlet section are an integral structure.

[0006] The above technical solution ensures that the various sections of the furnace body are connected in an orderly manner, making it adaptable to annealing processes in multiple scenarios.

[0007] Preferably, the first connecting section is a transition section between the second heating section and the third heating section, and an electric heating element is provided at the lower part of the first connecting section. The second connecting section is a transition section between the third heating section and the third connecting section and the outlet section, and an electric heating element is provided at the lower part of the second connecting section.

[0008] By adopting the above technical solution, temperature control can be achieved through an electric heating element, avoiding excessive temperature difference in silicon steel sheets and reducing thermal stress.

[0009] Preferably, the third connecting section is a cooling section, and the third connecting section uses a mixture of nitrogen and hydrogen gas to spray and cool the silicon steel sheet through a nozzle, wherein the ratio of nitrogen to hydrogen is 3:7.

[0010] By employing the above technical solution, the oxidation of silicon steel sheets can be prevented through a nitrogen-hydrogen mixture, thus ensuring surface quality.

[0011] Preferably, each of the heating section one, heating section two, and heating section three is equipped with an independent online oxygen analyzer, each of the heating section one, heating section two, and heating section three is equipped with a sampling port, and heating section three is equipped with an atmosphere supply system.

[0012] By adopting the above technical solution, atmosphere samples can be easily collected through the sampling port, and the three atmosphere parameters of the heating section can be accurately controlled.

[0013] Preferably, the furnace structure includes 16 independently driven No. 1 and No. 2 furnace roller groups. Each No. 1 and No. 2 furnace roller group comprises two rollers. There are two No. 1 furnace roller groups made of stainless steel, and 14 No. 2 furnace roller groups made of ceramic sleeves. The two stainless steel No. 1 furnace roller groups are respectively located in the inlet and outlet sections, while the remaining 14 ceramic sleeve No. 2 furnace roller groups are sequentially located in the heating section, connecting section, and outlet section. The ceramic sleeve No. 1 furnace roller groups are modular and interchangeable. Each No. 1 and No. 2 furnace roller group is equipped with an independent chain and sprocket. The two rollers within each No. 1 and No. 2 furnace roller group are independently connected via chains and sprockets. Each No. 1 and No. 2 furnace roller group is powered by a drive motor.

[0014] Using the above technical solution, the No. 1 and No. 2 furnace roller groups can be controlled independently by a separate drive motor to achieve single-process control of each processing section of silicon steel sheets.

[0015] Preferably, the process steps are as follows: Step 1, Feeding and Preheating Section: Silicon steel sheets enter the furnace structure through the stainless steel No. 1 furnace roller group in the inlet section. The initial volatile gases are discharged through the independent gas collection hood and exhaust pipe in the inlet section to ensure the centering accuracy of the strip. The silicon steel sheets enter the early stage of the heating section and are indirectly heated by furnace gas convection and radiation. The temperature is controlled to be lower than the ignition point of the rolling oil on the surface of the silicon steel sheets to remove the surface rolling oil, emulsion residue and moisture. The volatile oil and gas are discharged from the plant through the exhaust pipe. Step Two: Heating and Soaking Section; The silicon steel sheet sequentially passes through Heating Section One, Heating Section Two, and Heating Section Three. Each heating section has independent temperature control and is equipped with an online oxygen analyzer and sampling port. Heating is achieved indirectly through radiant tubes. A nitrogen-hydrogen mixed protective atmosphere is introduced, and the gas ratio is adjusted. The heating temperature is controlled according to the type of silicon steel. Specifically, the heating temperature control is as follows: For intermediate annealing scenarios, the temperature should be controlled at 800-900℃; For annealing of non-oriented silicon steel finished products, the temperature should be controlled at 800-950℃. For high-temperature annealing of grain-oriented silicon steel, the maximum controlled temperature is above 1200℃. Step 3, slow cooling section; the silicon steel sheet first passes through connecting section one and connecting section two, and is kept warm by the electric heating elements built into connecting section one and connecting section two, so that the strip steel is cooled from the annealing temperature to 550-650℃ at a controlled rate, which promotes carbide spheroidization and avoids the generation of thermal stress. Step 4, rapid cooling section; the silicon steel strip enters the third connecting section, where a mixture of nitrogen and hydrogen gas is sprayed through a nozzle to cool the strip to below 150°C to prevent oxidation; Step 5, Discharge and Post-processing Section: The cooled silicon steel sheets are discharged through the stainless steel No. 1 furnace roller group in the outlet section and enter the subsequent water quenching tank for strengthening treatment according to process requirements. The waste gas generated in each section is led out of the plant through independent exhaust pipes and cooling air exhaust pipes.

[0016] By adopting the above technical solution and following the above steps, the entire annealing process of silicon steel sheets can be controlled, adapting to the needs of multiple scenarios.

[0017] Preferably, the hydrogen content in the nitrogen-hydrogen mixed protective atmosphere in step two is 5%-20%; In step two, during the high-temperature annealing of the grain-oriented silicon steel, the holding time in heating section three is set according to the secondary recrystallization requirements to ensure the formation of {110}. <001> The oriented Goss texture allows the MgO release agent coated on the surface of the silicon steel sheet to react with the substrate to form a magnesium silicate glass film. In the annealing scenario of the non-oriented silicon steel finished product in step two, the nitrogen-hydrogen mixed atmosphere in heating section three is a decarburizing atmosphere, which removes harmful impurity elements such as carbon, nitrogen, and sulfur from the silicon steel sheet and optimizes the grain size to uniform equiaxed grains. In step two, pure nitrogen or a nitrogen-hydrogen mixture is introduced as a protective atmosphere and kept at a high temperature for several hours. The slow cooling treatment of connecting section one and connecting section two eliminates the internal stress generated during the forming and processing of silicon steel sheets without changing the material texture and grain size.

[0018] By adopting the above technical solution, the stable performance of the product can be ensured by adjusting the atmosphere and insulation parameters.

[0019] Preferably, in steps one to five, the running speed of the silicon steel sheet is adjusted by 16 sets of independently driven No. 1 furnace roller group and No. 2 furnace roller group, wherein the No. 2 furnace roller group with 14 sets of ceramic sleeves can be interchanged. The processing time of the silicon steel sheet in each process section is adjusted by controlling the running speed of the No. 1 furnace roller group and the No. 2 furnace roller group.

[0020] By adopting the above technical solution, the processing time of each process stage of silicon steel sheet can be adjusted to meet the annealing requirements of multiple scenarios.

[0021] Preferably, in step three, the cooling rates of connecting section one and connecting section two are achieved by adjusting the circulation speed of the protective gas within the furnace structure and the temperature of the electric heating element, and the blowing cooling rate of connecting section three is controlled according to the CCT curve of the silicon steel sheet.

[0022] By adopting the above technical solution, thermal stress and oxidation can be avoided by adjusting the cooling rate of each slow and fast cooling stage, thus ensuring the spheroidization of carbides and the stability of product performance.

[0023] Compared with the prior art, the beneficial effects of the present invention are: the experimental furnace for annealing silicon steel sheets and its process method are as follows: 1. The present invention is provided with three independent heating sections 1, 2 and 3, and three independent connecting sections 1, 2 and 3. Combined with an independent online oxygen analyzer, sampling port and atmosphere supply system, it can meet the needs of multiple scenarios such as intermediate annealing, non-oriented silicon steel finished product annealing and oriented silicon steel high temperature annealing. By controlling segmented temperatures above 800-1200℃, a nitrogen-hydrogen protective atmosphere with a ratio of 5%-20%, and the cooling rate, it is possible to achieve the desired temperature for grain-oriented silicon steel {110}. <001> The formation of the Goss texture and the generation of magnesium silicate glass film can also achieve the removal of impurities in non-oriented silicon steel and the optimization of uniform equiaxed grains, thereby avoiding the problems of single process adaptation and large performance fluctuation of traditional equipment. 2. In this invention, silicon wafers are conveyed by 16 sets of independently driven No. 1 and No. 2 furnace roller groups. The two No. 1 furnace roller groups are made of stainless steel and are respectively set in the inlet and outlet sections. The stainless steel No. 1 furnace roller groups in the inlet and outlet sections are matched with the normal temperature feeding and discharging scenarios. Stainless steel has good corrosion resistance and structural stability. The No. 2 furnace roller groups with ceramic sleeves are used in high-temperature areas such as the heating section and the connecting section. The ceramic sleeves have the characteristics of high temperature resistance, high temperature deformation resistance and atmospheric corrosion resistance. They can cope with high temperature annealing environments above 800-1200℃, avoid damage to the furnace roller groups under extreme working conditions, and avoid the problem that a single furnace roller group cannot adapt to multiple temperature ranges in the whole process. By adjusting the speed of the No. 1 and No. 2 furnace roller groups, the processing time of silicon steel sheets in each process stage can be controlled. Combined with segmented cooling of slow and fast cooling, experimental efficiency can be improved while ensuring the accuracy of experimental data, providing reliable data support for subsequent large-scale production and reducing the risk of technology transfer. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the furnace body layout structure of the present invention; Figure 2 This is a schematic diagram of the gas collection hood structure of the present invention; Figure 3 This is a schematic diagram of the furnace roller assembly structure of the present invention; Figure 4 This is a schematic diagram of the process structure of the present invention.

[0025] In the diagram: 1. Inlet section; 2. Heating section one; 3. Heating section two; 4. Heating section three; 5. Connecting section one; 6. Connecting section two; 7. Connecting section three; 8. Outlet section; 9. Gas collection hood; 10. No. 1 furnace roller group; 11. No. 2 furnace roller group. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Please see Figures 1-4 The present invention provides a technical solution: a test furnace for annealing silicon steel sheets and its process, comprising an inlet section 1, a heating section 1 2, a heating section 2 3, a heating section 3 4, a connecting section 1 5, a connecting section 2 6, a connecting section 3 7, an outlet section 8, a gas collecting hood 9, a first furnace roller group 10, and a second furnace roller group 11.

[0028] The furnace body structure consists of inlet section 1, heating section, connecting section, and outlet section 8. The furnace body structure is fixed to the workshop floor by two H-beams. The furnace body structure is equipped with three cooling air exhaust pipes, which lead out of the plant for exhaust. There are three heating sections: Heating Section 1 (2), Heating Section 2 (3), and Heating Section 3 (4). There are also three connecting sections: Connecting Section 1 (5), Connecting Section 2 (6), and Connecting Section 3 (7). Connecting Section 3 (7) and outlet section 8 form a single unit. Inlet section 1, connecting section 1 (5), connecting section 2 (6), and connecting section 3 (7), as well as outlet section 8, are each equipped with independent gas collection hoods (9) and exhaust pipes, which lead out of the plant for exhaust. Heating section 1 (2) is located on one side of inlet section 1. Heating section 2 (3) is located on the side of heating section 1 (away from heating section 1), and the connecting section is located on the other side of heating section 2 (3). Connecting section 1.5 is connected to heating section 3.4 on the other side of heating section 3.6 is connected to connecting section 3.7 on the other side of heating section 3.7 and outlet section 8 are an integral structure. Connecting section 1.5 is the transition section between heating section 2.3 and heating section 3.4. An electric heating element is installed at the bottom of connecting section 1.5. Connecting section 2.6 is the transition section between heating section 3.4, connecting section 3.7 and outlet section 8. An electric heating element is installed at the bottom of connecting section 2.7. Connecting section 3.7 is a cooling section. A mixture of nitrogen and hydrogen is sprayed through a nozzle to cool the silicon steel sheet. The ratio of nitrogen to hydrogen is 3:7. Heating sections 1.2, 2.3 and 3.4 are each equipped with an independent online oxygen analyzer. Sampling ports are provided in heating sections 1.2, 2.3 and 3.4. An atmosphere supply system is provided in heating section 3.4. The furnace structure includes 16 independently driven No. 1 furnace roller group 10 and No. 2 furnace roller group 11. Each No. 1 furnace roller group 10 and No. 2 furnace roller group 11 contains two rollers. There are two No. 1 furnace roller groups 10, which are made of stainless steel. There are 14 No. 2 furnace roller groups 11, which are made of ceramic sleeves. The two stainless steel No. 1 furnace roller groups 10 are located at the inlet section 1 and the outlet section 8, respectively. The remaining 14 are made of ceramic sleeves. The No. 2 furnace roller group 11 is sequentially arranged in the heating section, connecting section and outlet section 8; the No. 1 furnace roller group 10 of the ceramic sleeve is modular and interchangeable; each No. 1 furnace roller group 10 and the No. 2 furnace roller group 11 is equipped with an independent chain and sprocket, and the two rollers in the No. 1 furnace roller group 10 and the No. 2 furnace roller group 11 are independently connected by chains and sprockets, and each No. 1 furnace roller group 10 and the No. 2 furnace roller group 11 is powered by a drive motor; For example, 1. Figure 2 and Figure 3As shown, the furnace structure is assembled sequentially from inlet section 1, heating section 1 2, heating section 2 3, heating section 3 4, connecting section 1 5, connecting section 2 6, connecting section 3 7, and outlet section 8. Connecting section 3 7 and outlet section 8 are fixed together by welding. The furnace structure is horizontally fixed on the pre-set concrete foundation in the workshop floor using H-beams as supports. Three cooling air exhaust pipes are symmetrically installed on the top of the furnace structure. One end of the exhaust pipe is connected to the inside of the furnace, and the other end is connected to the outside of the factory building through a flange, extending to the inlet of the exhaust gas treatment device outside the factory building. Independent gas collection hoods 9 are installed on the top of inlet section 1, connecting section 1 5, connecting section 2 6, connecting section 3 7, and outlet section 8. The gas collection hoods 9 are made of stainless steel and welded together. The inner wall is smooth and without dead corners. Each gas collection hood 9 is connected to an exhaust pipe. The exhaust pipes are finally connected to the exhaust gas emission system outside the factory building. Radiant tube heating devices are installed inside heating sections 1 (2), 2 (3), and 3 (4), respectively. The radiant tubes are made of high-temperature resistant alloy material and are evenly distributed in each heating section. An online oxygen analyzer is installed in each heating section, with the oxygen analyzer probe extending into the furnace. Sampling ports are opened on the side of each heating section, and the sampling ports are equipped with sealing caps to facilitate real-time collection of furnace atmosphere samples. An atmosphere supply system is installed on one side of heating section 3 (4). Electric heating elements are installed at the lower part of connecting section 1 (5) and connecting section 2 (6). Connecting section 3 (7) serves as a cooling section and has several sets of nozzles installed inside. The nozzles face the direction of silicon steel sheet conveying. The nozzles are connected to the nitrogen-hydrogen mixed gas supply pipeline. A flow regulating valve is installed on the supply pipeline to adjust the blowing pressure and flow rate. The furnace body structure is equipped with a total of 16 sets of independently driven No. 1 furnace roller group 10 and No. 2 furnace roller group 11. Among them, two sets of No. 1 furnace roller group 10 are made of stainless steel and are installed in the inlet section 1 and outlet section 8 respectively. The remaining 14 sets of No. 2 furnace roller group 11 are made of ceramic sleeve material. Each set of No. 1 furnace roller group 10 and No. 2 furnace roller group 11 is equipped with an independent drive motor, chain and sprocket.

[0029] Step 1, Feeding and Preheating Section: Silicon steel sheets enter the furnace structure through the stainless steel No. 1 furnace roller group 10 in the inlet section 1. The initial volatile gases in the inlet section 1 are discharged through the independent gas collection hood 9 and exhaust pipe to ensure the centering accuracy of the strip. The silicon steel sheets enter the early stage of the heating section and are indirectly heated by furnace gas convection and radiation. The temperature is controlled to be lower than the ignition point of the rolling oil on the surface of the silicon steel sheets to remove the surface rolling oil, emulsion residue and moisture. The volatile oil and gas are discharged from the plant through the exhaust pipe. Step 2: Heating and Soaking Section; The silicon steel sheet sequentially passes through heating section 1 (2), heating section 2 (3), and heating section 3 (4). Each heating section has independent temperature control and is equipped with an online oxygen analyzer and sampling port. Heating is achieved indirectly through radiant tubes. A nitrogen-hydrogen mixed protective atmosphere is introduced and the gas ratio is adjusted. The heating temperature is controlled according to the type of silicon steel. Specifically, the heating temperature control is as follows: For intermediate annealing scenarios, the temperature should be controlled at 800-900℃; For annealing of non-oriented silicon steel finished products, the temperature should be controlled at 800-950℃. For high-temperature annealing of grain-oriented silicon steel, the maximum controlled temperature is above 1200℃. Step 3, slow cooling section; the silicon steel sheet first passes through connecting section 5 and connecting section 6, and is kept warm by the built-in electric heating elements of connecting section 5 and connecting section 6, so that the strip steel is cooled from the annealing temperature to 550-650℃ at a controlled rate, which promotes carbide spheroidization and avoids the generation of thermal stress. Step 4, rapid cooling section; the silicon steel strip enters the connecting section 37, where a mixture of nitrogen and hydrogen gas is sprayed through the nozzle to cool the strip to below 150°C to prevent oxidation; Step 5, Discharge and Post-processing Section: The cooled silicon steel sheets are discharged through the stainless steel No. 1 furnace roller group 10 of the outlet section 8, and enter the subsequent water quenching tank for strengthening treatment according to process requirements. The waste gas generated in each section is discharged outside the plant through independent exhaust pipes and cooling air exhaust pipes. The hydrogen content in the nitrogen-hydrogen mixed protective atmosphere in step two is 5%-20%; In step two, during the high-temperature annealing of grain-oriented silicon steel, the holding time in heating section 3 (4) is set according to the secondary recrystallization requirements to ensure the formation of {110}. <001> The oriented Goss texture allows the MgO release agent coated on the surface of the silicon steel sheet to react with the substrate to form a magnesium silicate glass film. In step two, during the annealing of the non-oriented silicon steel finished product, the nitrogen-hydrogen mixed atmosphere in heating section 3 is a decarburizing atmosphere, which removes harmful impurities such as carbon, nitrogen, and sulfur from the silicon steel sheet and optimizes the grain size to uniform equiaxed grains. In step two, pure nitrogen or a nitrogen-hydrogen mixture is introduced as a protective atmosphere and kept at a high temperature for several hours. The internal stress generated during the forming and processing of silicon steel sheets is eliminated through the slow cooling treatment of connecting section 1 5 and connecting section 2 6, without changing the material texture and grain size. In steps one through five, the running speed of the silicon steel sheet is adjusted by 16 sets of independently driven No. 1 furnace roller group 10 and No. 2 furnace roller group 11. Among them, the No. 2 furnace roller group 11 with 14 sets of ceramic sleeves can be interchanged. The processing time of the silicon steel sheet in each process section is adjusted by controlling the running speed of No. 1 furnace roller group 10 and No. 2 furnace roller group 11. In step three, the cooling rates of connecting section 5 and connecting section 6 are achieved by adjusting the circulation speed of the protective gas in the furnace structure and the temperature of the electric heating element, while the spray cooling rate of connecting section 7 is controlled according to the CCT curve of the silicon steel sheet. like Figure 1 and Figure 4As shown, the stainless steel No. 1 furnace roller group 10 of the inlet section 1 is started, the speed of the furnace roller group is adjusted, and the silicon steel sheet is fed into the furnace structure through the inlet section 1 to ensure the centering accuracy of the strip. The independent gas collection hood 9 and exhaust pipe of the inlet section 1 are opened to discharge the initial volatile gas carried by the silicon steel sheet when it enters. After the silicon steel sheet enters the early heating zone, it is indirectly heated by furnace gas convection and radiation. The temperature of this zone is controlled to be lower than the ignition point of the rolling oil on the surface of the silicon steel sheet. The temperature is maintained at this temperature for 30 minutes to remove the rolling oil, emulsion residue and moisture on the surface of the silicon steel sheet. The oil and gas generated by volatilization are discharged from the plant to the waste gas treatment device through the exhaust pipe. The silicon steel sheets continue to be conveyed through the No. 2 furnace roller group 11, sequentially entering heating section 1 (2), heating section 2 (3), and heating section 3 (4). Each heating section is independently temperature-controlled according to a preset temperature, and is indirectly heated through radiant tubes. Simultaneously, the atmosphere supply system is activated, introducing a nitrogen-hydrogen mixed protective atmosphere, with the hydrogen content controlled between 5% and 20%, the specific ratio adjusted according to the type of silicon steel. For non-oriented silicon steel finished product annealing, the nitrogen-hydrogen mixed atmosphere in heating section 3 (4) is a decarburizing atmosphere, with the hydrogen content adjusted to 15%-20%. This atmosphere adjustment removes harmful impurities such as carbon, nitrogen, and sulfur from the silicon steel sheets, optimizing the grain size to uniform equiaxed grains. For oriented silicon steel high-temperature annealing, the holding time in heating section 3 (4) is set according to the secondary recrystallization requirements to ensure the formation of {110}. <001> The oriented Goss texture allows the MgO isolator coated on the silicon steel sheet to react with the substrate to form a magnesium silicate glass film. During the process, samples of the furnace atmosphere can be collected periodically through the sampling ports of each heating section for composition analysis. The atmosphere supply parameters can be fine-tuned based on the analysis results. After passing through the heating and soaking section, the silicon steel sheet enters the connecting section 5 and the connecting section 6. The electric heating elements in the two connecting sections are activated. The electric heating elements maintain the temperature and control the cooling rate, cooling the strip steel from the annealing temperature to 550-650℃ at a controlled rate. The specific cooling endpoint temperature is determined according to the type of silicon steel. The cooling rate is achieved by adjusting the circulation speed of the protective gas in the furnace structure and the temperature of the electric heating elements to ensure a stable cooling process, promote carbide spheroidization, and avoid the generation of thermal stress. When the silicon steel sheet enters the third section 7, the nitrogen-hydrogen mixed gas supply system is activated, and a mixed gas with a nitrogen-hydrogen ratio of 3:7 is introduced. The mixed gas is sprayed through the nozzle to cool the silicon steel sheet, rapidly cooling the strip to below 150°C to prevent oxidation of the silicon steel sheet surface. The spray cooling rate of the third section 7 is precisely controlled according to the CCT curve of the silicon steel sheet, which is achieved by adjusting the gas flow rate and pressure of the nozzle to ensure the stable performance of the cooled silicon steel sheet. After cooling, the silicon steel sheets are discharged through the stainless steel No. 1 furnace roller group 10 of the outlet section 8. According to the process requirements, the discharged silicon steel sheets are sent to the subsequent water quenching tank for strengthening treatment. If water quenching treatment is not required, they are directly sent to the winding device. During the entire process, the waste gas generated in each section is led out of the plant through independent exhaust pipes and cooling air exhaust pipes. After being treated by the waste gas treatment device to meet the standards, it is discharged.

[0030] Working principle: The furnace body consists of inlet section 1, three independent heating sections, three connecting sections, and outlet section 8. It is equipped with an independent exhaust and atmosphere control system. After the silicon steel sheet is fed into inlet section 1, it is first removed from rolling oil, moisture, and other impurities in the preheating section at a low temperature. Then it passes through the three heating sections in sequence, with independent temperature control according to the annealing scenario. A nitrogen-hydrogen protective atmosphere with a hydrogen content of 5%-20% is introduced. The atmosphere is precisely controlled with an online oxygen analyzer and sampling port. Then it is slowly cooled to 550-650℃ in the two connecting sections to avoid thermal stress. Next, a 3:7 nitrogen-hydrogen mixture is sprayed in the third connecting section to quickly cool it to below 150℃ to prevent oxidation. Finally, it is discharged from outlet section 8. Through segmented temperature control, atmosphere adjustment, and gradient cooling, it adapts to the annealing requirements of multiple scenarios and optimizes the microstructure and performance of silicon steel.

[0031] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention.

Claims

1. A process method for an annealing test furnace for silicon steel sheets, characterized in that: The process steps are as follows: Step 1, Feeding and Preheating Section: Silicon steel sheets enter the furnace structure through the stainless steel No. 1 furnace roller group (10) of the inlet section (1). The initial volatile gas is discharged through the independent gas collection hood (9) and exhaust pipe to ensure the centering accuracy of the strip steel. The silicon steel sheets enter the early stage of the heating section and are indirectly heated by furnace gas convection and radiation. The temperature is controlled to be lower than the ignition point of the rolling oil on the surface of the silicon steel sheets to remove the surface rolling oil, emulsion residue and moisture. The volatile oil and gas are discharged from the plant through the exhaust pipe. Step 2, Heating and Soaking Section; The silicon steel sheet passes through heating section one (2), heating section two (3), and heating section three (4) in sequence. Each heating section has independent temperature control and is equipped with an online oxygen analyzer and sampling port. It is indirectly heated through a radiation tube, and a nitrogen-hydrogen mixed protective atmosphere is introduced and the gas ratio is adjusted. The heating temperature is controlled according to the type of silicon steel. The specific control of the heating temperature is as follows: For intermediate annealing scenarios, the temperature should be controlled at 800-900℃; For annealing of non-oriented silicon steel finished products, the temperature should be controlled at 800-950℃. For high-temperature annealing of grain-oriented silicon steel, the maximum controlled temperature is above 1200℃. Step 3, slow cooling section; the silicon steel sheet first passes through connecting section one (5) and connecting section two (6), and is kept warm by the electric heating elements built into connecting section one (5) and connecting section two (6), and the strip steel is cooled from the annealing temperature to 550-650℃ at a controlled rate to promote carbide spheroidization and avoid the generation of thermal stress. Step 4, rapid cooling section; the silicon steel sheet enters the connecting section 3 (7), and is cooled by blowing a mixture of nitrogen and hydrogen through the nozzle to cool the strip steel to below 150°C to prevent oxidation; Step 5, Discharge and Post-processing Section: The cooled silicon steel sheets are discharged through the stainless steel No. 1 furnace roller group (10) of the outlet section (8), and enter the subsequent water quenching tank for strengthening treatment according to process requirements. The waste gas generated in each section is discharged outside the plant through independent exhaust pipes and cooling air exhaust pipes.

2. The process method for an annealing test furnace for silicon steel sheets according to claim 1, characterized in that: The hydrogen content in the nitrogen-hydrogen mixed protective atmosphere in step two is 5%-20%; In the high-temperature annealing scenario of oriented silicon steel in step two, the holding time of heating section three (4) is set according to the secondary recrystallization requirement to ensure the formation of {110}. <001> The oriented Goss texture allows the MgO release agent coated on the surface of the silicon steel sheet to react with the substrate to form a magnesium silicate glass film. In the annealing scenario of the non-oriented silicon steel finished product in step two, the nitrogen-hydrogen mixed atmosphere of heating section three (4) is a decarburizing atmosphere, which removes harmful impurities such as carbon, nitrogen, and sulfur from the silicon steel sheet and optimizes the grain size to uniform equiaxed grains. In step two, pure nitrogen or a nitrogen-hydrogen mixture is introduced as a protective atmosphere and kept at a high temperature for several hours. The internal stress generated during the forming and processing of silicon steel sheets is eliminated by the slow cooling treatment of connecting section one (5) and connecting section two (6) without changing the material texture and grain size.

3. The process method for an annealing test furnace for silicon steel sheets according to claim 1, characterized in that: In steps one to five, the running speed of the silicon steel sheet is adjusted by 16 sets of independently driven No. 1 furnace roller group (10) and No. 2 furnace roller group (11), of which 14 sets of ceramic sleeve No. 2 furnace roller group (11) can be replaced by each other. The processing time of the silicon steel sheet in each process section is controlled by controlling the running speed of No. 1 furnace roller group (10) and No. 2 furnace roller group (11).

4. The process method for an annealing test furnace for silicon steel sheets according to claim 1, characterized in that: In step three, the cooling rate of connecting section one (5) and connecting section two (6) is achieved by adjusting the circulation speed of the protective gas in the furnace structure and the temperature of the electric heating element, and the blowing cooling rate of connecting section three (7) is controlled according to the CCT curve of silicon steel sheet.

5. A silicon steel sheet annealing test furnace, applied in the process method of the silicon steel sheet annealing test furnace as described in any one of claims 1-4, characterized in that: It includes an inlet section (1), a heating section, a connecting section and an outlet section (8). The inlet section (1), heating section, connecting section and outlet section (8) constitute the furnace body structure. The furnace body structure is fixedly installed on the floor of the workshop by two H-beams. The furnace body structure is equipped with three cooling air exhaust pipes, which are led out of the factory building for exhaust. The heating section is provided with three sections, namely heating section one (2), heating section two (3) and heating section three (4); the connecting section is provided with three sections, namely connecting section one (5), connecting section two (6) and connecting section three (7); the connecting section three (7) and the outlet section (8) form a whole. The inlet section (1), connecting section one (5), connecting section two (6) and connecting section three (7) and the outlet section (8) are respectively provided with independent gas collection hoods (9) and exhaust pipes. The exhaust pipes are led out of the factory building for discharge.

6. A test furnace for annealing silicon steel sheets according to claim 5, characterized in that: A heating section 1 (2) is provided on one side of the inlet section (1). A heating section 2 (3) is provided on the side of the heating section 1 (2) away from the heating section 1 (2). A connecting section 1 (5) is provided on the other side of the heating section 2 (3). A heating section 3 (4) is provided on the other side of the connecting section 1 (5). A connecting section 2 (6) is provided on the other side of the heating section 3 (4). The connecting section 2 (6) is connected to the connecting section 3 (7). The connecting section 3 (7) and the outlet section (8) are an integral structure.

7. A test furnace for annealing silicon steel sheets according to claim 5, characterized in that: The first connecting section (5) is a transition section between the second heating section (3) and the third heating section (4). An electric heating element is provided at the lower part of the first connecting section (5). The second connecting section (6) is a transition section between the third heating section (4), the third connecting section (7), and the outlet section (8). An electric heating element is provided at the lower part of the second connecting section (6).

8. A test furnace for annealing silicon steel sheets according to claim 5, characterized in that: The third connecting section (7) is a cooling section. The third connecting section (7) uses a mixture of nitrogen and hydrogen gas to spray and cool the silicon steel sheet through a nozzle. The ratio of nitrogen to hydrogen is 3:

7.

9. A test furnace for annealing silicon steel sheets according to claim 5, characterized in that: Each of the heating section 1 (2), heating section 2 (3) and heating section 3 (4) is equipped with an independent online oxygen analyzer. Each of the heating section 1 (2), heating section 2 (3) and heating section 3 (4) is equipped with a sampling port. Each of the heating section 3 (4) is equipped with an atmosphere supply system.

10. A test furnace for annealing silicon steel sheets according to claim 5, characterized in that: The furnace structure is equipped with 16 sets of independently driven No. 1 furnace roller group (10) and No. 2 furnace roller group (11). Each No. 1 furnace roller group (10) and No. 2 furnace roller group (11) includes two rollers. There are 2 sets of No. 1 furnace roller group (10) made of stainless steel. There are 14 sets of No. 2 furnace roller group (11) made of ceramic sleeve material. The 2 sets of No. 1 furnace roller group (10) made of stainless steel are respectively set in the inlet section (1) and the outlet section (8). The remaining 14 sets of No. 2 furnace roller group (11) made of ceramic sleeve material are set in the heating section, the connecting section and the outlet section (8) in sequence. The No. 1 furnace roller group (10) made of ceramic sleeve material is modular and interchangeable. Each of the No. 1 furnace roller group (10) and the No. 2 furnace roller group (11) is equipped with an independent chain and sprocket. The two rollers in the No. 1 furnace roller group (10) and the No. 2 furnace roller group (11) are independently connected by a chain and a sprocket. Each of the No. 1 furnace roller group (10) and the No. 2 furnace roller group (11) is powered by a drive motor.

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