A device and process for improving interlayer resistance of oriented silicon steel

Abstract

The present invention discloses a device for improving the interlayer resistance of oriented silicon steel and a process thereof. The device of the present invention includes different air inlet pipes, which respectively input oxygen, hydrogen and nitrogen into a heat treatment furnace. The heat treatment furnace includes a furnace body and a furnace cover plate. The furnace body is provided with an air flow baffle hanging from the furnace bottom plate and a placement rack for placing steel coils; one end of the air flow baffle is in contact with the furnace wall on the air inlet side of the heat treatment furnace body; and is not in contact with the furnace wall on the side where the gas outlet main pipe is located. The device of the present invention has a small footprint and high energy utilization rate. It performs micro-processing on the surface of oriented silicon steel, and the surface film layer becomes denser, and the interlayer resistance is greatly improved. At the same time, the use of the device and a suitable process can further improve the quality of the insulating layer on the surface of oriented silicon steel, significantly improving the surface resistance of oriented silicon steel.

Description

Technical Field

[0001] The present invention relates to the technical field of oriented silicon steel preparation, and in particular to a device for improving interlayer resistance of oriented silicon steel and a process thereof. Background Art

[0002] Grain-oriented silicon steel is an essential magnetic material in transformer manufacturing. To reduce energy loss during transformer power transmission, an insulating layer is applied to the surface of the oriented silicon steel to insulate the silicon steel sheets from each other. As the voltages transmitted by transformers increase, the insulation resistance requirements for the oriented silicon steel surface are also becoming increasingly stringent.

[0003] The current national standard requires that the surface resistance of oriented silicon steel sheets is 15Ω·cm 2 , which can no longer meet the increasingly high surface resistance requirements. Chinese patent CN107630134B discloses a method for improving the interlayer resistance of cold-rolled electrical steel products. The invention controls the nitrogen dew point during the cooling process of the cold-rolled electrical steel strip after grain growth, performs surface modification on the electrical steel, and improves the surface interlayer resistance. However, the process described in the invention is only applicable to non-oriented silicon steel that has not been coated on the surface, and is not applicable to oriented silicon steel. The nitrogen dew point of oriented silicon steel has been controlled in production. And because non-oriented silicon steel has lower insulation performance requirements than oriented silicon steel, the 300~3000Ω·mm improved by the invention 2 , equivalent to 3 to 30Ω·cm 2 , the improvement effect is limited.

[0004] Currently, the most direct and effective method is to increase the amount of insulating coating, that is, to apply more insulating coating. This method can improve the resistance to a certain extent, but the improvement is limited, and it will also cause a significant increase in production costs. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention provides a device and process for improving the interlayer resistance of grain-oriented silicon steel. The device, which occupies a small footprint and has high energy efficiency, micro-processes the surface of grain-oriented silicon steel, making the surface film denser and significantly increasing the interlayer resistance. Furthermore, using this device in conjunction with appropriate processes can further improve the quality of the insulation layer on the surface of grain-oriented silicon steel, significantly increasing the surface resistance of the steel.

[0006] The technical solutions of the present invention are as follows:

[0007] A device for improving the interlayer resistance of oriented silicon steel, comprising an air inlet branch pipe, a gas heating pipe 4, an air inlet main pipe 5, an air inlet branch pipe 6, an air outlet main pipe 11, and a heat treatment furnace; the air inlet branch pipe comprises a nitrogen air inlet branch pipe 1, a hydrogen air inlet branch pipe 2, and an oxygen air inlet branch pipe 3; the air inlet branch pipe and the air inlet branch pipe 6 are connected in sequence through the gas heating pipe 4 and the air inlet main pipe 5; the air inlet branch pipe 6 comprises a plurality of branch pipes, and the plurality of branch pipes are all arranged on the furnace wall at the air inlet end of the heat treatment furnace; the air outlet main pipe 11 is arranged on the furnace wall at the air outlet end of the heat treatment furnace; the heat treatment furnace comprises a furnace body and a furnace cover 12, and the outside of the furnace body is the furnace wall; an air flow baffle 10 and a placement rack 9 are arranged inside the furnace body; the air flow baffle 10 is vertically arranged on the furnace bottom plate, and one end of the air flow baffle 10 is in contact with the furnace wall on the air inlet side of the heat treatment furnace body; and does not contact the furnace wall on the side where the air outlet main pipe 11 is located.

[0008] In one embodiment, the furnace cover 12 is covered by the furnace body of the heat treatment furnace.

[0009] In one embodiment, the air flow baffle 10 is disposed between adjacent air intake pipes.

[0010] In one embodiment, both ends of the heat treatment furnace are arc-shaped.

[0011] In one embodiment, the furnace wall of the air inlet end of the heat treatment furnace is a continuous wavy structure, and the air inlet branch pipe 6 is arranged in the middle position of each wavy raised part; the air flow baffle 10 is arranged at the intersection of adjacent waves and on the extension line from the air inlet end to the air outlet end; the air outlet end of the heat treatment furnace is arc-shaped.

[0012] In one embodiment, the furnace wall includes an outer furnace wall 7 and an inner furnace wall 8; vacuum pumps and control valves are installed on both the air inlet pipe and the air outlet pipe.

[0013] In one embodiment, the air flow baffle 10 is welded to the heat treatment furnace; the placement rack 9 is arranged on the furnace bottom plate of the heat treatment furnace; the placement rack 9 includes a base 16 inclined from high to low and a gasket 15 arranged on the base 16; the inclination angle of the base is 20 to 35°, preferably 30°.

[0014] The present invention also protects a method for increasing interlayer resistance of oriented silicon steel, comprising the following steps:

[0015] (1) Place the oriented silicon steel coils 14 coated with the insulating coating on the gaskets 15 of the placement rack 9 of the device in sequence, close the furnace cover 12 to ensure sealing; and evacuate the furnace with a vacuum pump;

[0016] (2) The oriented silicon steel coil is then treated by controlling the atmosphere and temperature.

[0017] In one embodiment, in step (2), the specific process of the processing is:

[0018] (2-1) Open the valves of the nitrogen inlet branch pipe 1, the oxygen inlet branch pipe 3, and the outlet main pipe 11, mix the nitrogen and oxygen and let them enter the gas heating pipe 4, heat the mixed gas with a heating device, and when the temperature reaches 650-700°C, pass the mixed gas into the furnace and continue to pass the mixed gas for 16-18 hours;

[0019] (2-2) Close the valve of oxygen inlet branch pipe 3, heat nitrogen to 700-750°C, and continuously introduce nitrogen for 1-2 hours;

[0020] (2-3) After heating the nitrogen to 750-800°C, open the valve of the hydrogen inlet branch pipe 2 and introduce a mixture of nitrogen and hydrogen. Continue to introduce the mixture for 4-6 hours, and then burn the exhausted gas.

[0021] (2-4) Close the valve of the hydrogen inlet branch pipe 2, heat the nitrogen to 400-500°C, and continue to pass it for 1-2 hours. Then, pass nitrogen at room temperature into the furnace until the temperature inside the furnace drops to 180-200°C, close the inlet valve and the outlet valve; open the furnace cover 12 and cool it to room temperature.

[0022] In one embodiment, in step (2-1), the oxygen content in the mixed gas is 0.2-0.4%; when the mixed gas is continuously passed, the gas flow rate is 12-20m 3 / h.

[0023] In one embodiment, in step (2-2), the nitrogen gas flow rate is 16-20m 3 / h, and the oxygen content in the atmosphere of the heat treatment furnace is less than 100ppm.

[0024] In one embodiment, in step (2-3), the hydrogen content in the mixed gas is 0.5-0.8%; the amount of hydrogen and nitrogen introduced is 16-20m 3 / h.

[0025] In the traditional oriented silicon steel production process, after the insulating coating is applied to the oriented silicon steel sheet, it needs to be quickly dried and sintered, taking no more than 1 minute. The resulting coating often contains numerous cracks and pores, which affect the surface coating's density and, consequently, its insulation properties. In the present invention, the oriented silicon steel coil is subjected to a prolonged high-temperature treatment, where the surface coating slowly heals at high temperatures. Ultimately, cracks and pores on the oriented silicon steel surface are significantly reduced, and the coating's insulation properties are significantly improved.

[0026] The beneficial technical effects of the present invention are:

[0027] (1) The present invention improves gas flow and utilization efficiency within the device by providing partitions and by creating an arc-shaped heat treatment furnace, thereby reducing gas flow dead zones. This improved gas flow allows gas to enter the interior of the steel coil, micro-processing the steel coil and significantly improving the insulation properties of the coating.

[0028] (2) The existing insulating coating on the surface of oriented silicon steel is not absolutely uniform, and there will be certain micro-areas that are not coated and are exposed. The insulation properties of these exposed points are relatively poor. The present invention introduces 0.2-0.4% oxygen at the initial stage of the process, so that the micro-areas of the silicon steel matrix exposed on the surface of the oriented silicon steel are oxidized, reducing the low-resistance areas, thereby improving the overall interlayer resistance of the oriented silicon steel.

[0029] (3) Because the tension between the silicon steel coils is extremely large, it is difficult for gas to enter the middle of the steel coil. Therefore, it generally takes a long time to complete the gas penetration. When oxygen enters the middle of the steel coil to react, the edge of the steel coil has begun to overoxidize. The present invention reduces the edge of the steel coil by introducing a certain amount of hydrogen after introducing nitrogen at 750-800°C to ensure that the plate surface is not yellowed or reddish. Here, hydrogen is introduced to reduce the overoxidized area, which can eliminate the oxidation problem, but cannot improve the oxidation resistance of the edge.

[0030] (3) The coating repair device of the present invention adopts a one-furnace-multiple-roll setting, which can process multiple rolls of oriented silicon steel at one time, greatly improving production efficiency.

[0031] (4) The present invention rationally utilizes the heat of waste gas generated during the production of oriented silicon steel to heat-treat the gas to be heated, thereby greatly reducing energy waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a structural diagram of an embodiment of the present invention.

[0033] Figure 2 It is a structural diagram of another embodiment of the present invention.

[0034] Figure 3 Schematic diagram of the internal structure of an embodiment of the present invention.

[0035] Figure 4 Schematic diagram of the present invention including a furnace cover.

[0036] Figure 5 It is a schematic diagram of the furnace cover structure of the present invention.

[0037] Figure 6 It is a structural schematic diagram of the placement rack of the present invention.

[0038] Figure 7 This is the surface topography before processing by the present invention.

[0039] Figure 8 This is the surface morphology after treatment according to the present invention.

[0040] In the figure: 1 is the nitrogen inlet branch pipe; 2 is the hydrogen inlet branch pipe; 3 is the oxygen inlet branch pipe; 4 is the gas heating pipe; 5 is the air inlet main pipe; 6 is the air inlet branch pipe; 7 is the outer furnace wall; 8 is the inner furnace wall; 9 is the placement rack; 10 is the air flow baffle; 11 is the air outlet main pipe; 12 is the furnace cover; 13-1 is the connecting piece I; 13-2 is the connecting piece II; 14 is the steel coil; 15 is the gasket; 16 is the base. DETAILED DESCRIPTION

[0041] The present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0042] like Figure 1-6 As shown, the apparatus of the present invention includes: an air inlet branch pipe, a gas heating pipe 4, an air inlet main pipe 5, an air inlet branch pipe 6, an air outlet main pipe 11, and a heat treatment furnace. The air inlet branch pipes include a nitrogen air inlet branch pipe 1, a hydrogen air inlet branch pipe 2, and an oxygen air inlet branch pipe 3. The air inlet branch pipes and the air inlet branch pipes 6 are connected in turn via the gas heating pipe 4 and the air inlet main pipe 5. The air inlet branch pipe 6 includes multiple branch pipes, each of which is installed on the air inlet wall of the heat treatment furnace. The air outlet main pipe 11 is installed on the air outlet wall of the heat treatment furnace. Gas can enter and exit the heat treatment furnace through the air inlet branch pipes and the air inlet and outlet branch pipes. By providing multiple branch pipes, gas can better enter different areas of the heat treatment furnace where steel coils are distributed, and the gas distribution is more uniform.

[0043] In the present invention, the gas flow is achieved by controlling the gas pressure in the air inlet pipe to be greater than that in the furnace, and the gas pressure in the furnace to be greater than that in the air outlet pipe. The gas flows under the drive of the gas pressure, so the air outlet main pipe is connected to the furnace body.

[0044] In one embodiment of the present invention, a gas heating device is provided in the middle of the air inlet pipe, and the temperature is measured by a built-in thermocouple to perform feedback adjustment on the actual temperature and the set temperature.

[0045] In one embodiment of the present invention, valves are provided on the air inlet branch pipe, the air inlet main pipe, the air inlet branch pipe and the air outlet main pipe to control the flow of gas.

[0046] In one embodiment of the present invention, an intake branch pipe 6 is provided at one end of the intake manifold 5, away from the intake branch pipes. This allows mixed gases to flow into different areas of the furnace. Specifically, nitrogen, hydrogen, and oxygen are supplied to the intake manifold through the respective intake branch pipes. The intake manifold then distributes the gases to the intake branch pipes and, in turn, to each area. The selection of gases is controlled by valves.

[0047] like Figure 3-5As shown, the heat treatment furnace includes a furnace body and a furnace cover 12. The exterior of the furnace body is the furnace wall. Inside the furnace body, airflow baffles 10 and a storage rack 9 are installed. The airflow baffles 10 separate the zones, ensuring that the overall airflow direction is from the air inlet to the air outlet, and reducing dead zones within the furnace.

[0048] In one embodiment of the present invention, the furnace cover 12 is connected to the furnace body through the connecting piece I 13 - 1 on the furnace cover and the connecting piece II 13 - 2 on the furnace body by bolts, so that the furnace cover and the furnace body of the heat treatment furnace are covered.

[0049] In one embodiment of the present invention, the gases in the nitrogen intake branch pipe 1, the hydrogen intake branch pipe 2 and the oxygen intake branch pipe 3 can be mixed and enter the gas heating pipe 4, and then enter the heat treatment furnace through the intake main pipe 5 and the intake branch pipe 6.

[0050] In one embodiment of the present invention, the air flow baffle 10 is vertically arranged on the furnace bottom plate, and one end of the air flow baffle 10 contacts the furnace wall on the air inlet side of the heat treatment furnace body; and does not contact the furnace wall on the side where the gas outlet main pipe 11 is located.

[0051] In one embodiment of the present invention, the airflow baffles 10 are positioned between adjacent air inlet manifolds to facilitate gas flow from corresponding channels into the area formed by the airflow baffles, thereby preventing gas from being dispersed by the entire flow. By providing different airflow baffles and air inlet manifolds, gas can be better directed to the location where the steel coils are positioned, improving processing efficiency and conserving resources.

[0052] In one embodiment of the present invention, both ends of the heat treatment furnace are arc-shaped. Because the coating repair device involves hydrogen and high temperature, the present invention provides rounded corners at places where the device is prone to produce gas flow dead zones (the side of the furnace close to the air inlet branch pipe, and the side close to the air outlet main pipe) to prevent residual oxygen in the dead zones.

[0053] In one embodiment of the present invention, the heat treatment furnace's inlet wall has a continuous wavy structure, with an inlet manifold 6 positioned midway between each wavy raised portion. Airflow baffles 10 are positioned at the intersection of adjacent waves and extend from the inlet to the outlet. The heat treatment furnace's outlet is arc-shaped. This wavy structure allows for better gas partitioning and flow.

[0054] In one embodiment of the present invention, the furnace wall includes an outer furnace wall 7 and an inner furnace wall 8; the inner furnace wall 7 is made of refractory material, and the outer furnace wall 8 is made of steel.

[0055] In one embodiment of the present invention, vacuum pumps and control valves are installed on both the inlet and outlet pipes to control other flow rates. At the same time, the pipes are heated by a heating device to change the gas temperature.

[0056] like Figure 5 As shown, the airflow baffle 10 is welded to the heat treatment furnace. The placement rack 9 is installed on the furnace floor of the heat treatment furnace. The placement rack 9 includes a base 16 that is tilted from high to low and a gasket 15 installed on the base 16. The tilt angle of the base is 20-35 degrees, preferably 30 degrees. This tilt angle can better facilitate the placement and removal of steel coils. If the angle is too large or too small, the steel coil will be unstable or difficult to handle. The steel coil 14 is placed on the gasket 15. To facilitate gas penetration into the coil, the axial direction of the coil is consistent with the airflow direction.

[0057] In one embodiment of the present invention, the air flow baffle 10 is built with refractory materials and is used to separate the space so that the air flow direction flows from the air inlet pipe to the air outlet pipe, maintains a certain distance from the steel coil, and is placed parallel to the steel coil.

[0058] In the present invention, except for the air inlet and outlet, the entire device is a closed system. The furnace cover is opened when the steel coil is hoisted and closed when the steel coil is processed.

[0059] The specific working process of using the equipment of the present invention to improve the interlayer resistance of oriented silicon steel is as follows:

[0060] (1) Place the insulatingly coated oriented silicon steel coils 14 sequentially onto the gaskets 12 of the placement rack 9 of the apparatus, close the furnace cover 12 to ensure tightness, and evacuate the furnace using a vacuum pump. The vacuum pump is installed on the inlet and outlet pipes to control the air pressure, i.e., the vacuum level, in each section. To evacuate, close the inlet valve, open the outlet valve, and turn on the outlet pump to evacuate.

[0061] (2) The oriented silicon steel coil is treated by controlling the atmosphere and temperature, that is, four stages of atmosphere and temperature treatment are performed:

[0062] (2-1) Open the valves of the nitrogen inlet branch pipe 1, the oxygen inlet branch pipe 3 and the outlet main pipe 11, mix the nitrogen and oxygen and let them enter the gas heating pipe 4, heat the mixed gas with a heating device, and when the temperature reaches 650-700°C, pass the mixed gas into the furnace and continue to pass the mixed gas for 16-18 hours; wherein, the heating is carried out in the inlet branch pipe, and there is a special gas heating device, which is tubular, in which the gas is heated. In the mixed gas, the oxygen content accounts for 0.2-0.4% of the mixed gas; when the mixed gas is continuously passed, the gas flow rate is 12-20m 3 / h. The gas flow is controlled by controlling the valve opening and the pressure difference at both ends. There is equipment that can detect the gas composition in the furnace online and control the valve opening and pressure difference of each gas based on the detection results.

[0063] (2-2) Close the valve of oxygen inlet branch pipe 3, heat nitrogen to 700-750℃, heat it in the pipeline before passing it in, and start heating it after closing the oxygen valve. Continue to pass it in for 1-2 hours, with a gas flow rate of 16-20m 3 / h, at which point the oxygen content in the furnace atmosphere must be below 100ppm. The oxygen valve is closed, and nitrogen is continuously introduced to remove oxygen and reduce the oxygen content in the furnace. Nitrogen is heated independently, and the gases do not react with each other. The temperature is designed to repair the surface coating.

[0064] (2-3) After heating the nitrogen to 750-800°C, open the valve of the hydrogen inlet branch pipe 2, and introduce a mixture of nitrogen and hydrogen. Continue to introduce them for 4-6 hours, and the discharged gas is burned. The hydrogen is mixed with the nitrogen at room temperature. The hydrogen mixing ratio is also 0.5-0.8% as mentioned later. Continue to introduce the gas at a flow rate of 16-20m 3 / h; the outlet valve is always in the open state when gas enters the furnace.

[0065] (2-4) Close the valve of the hydrogen inlet branch pipe 2, heat pure nitrogen (pure nitrogen here refers to pure nitrogen supply gas, the purpose of which is to remove hydrogen from the pipeline and the device) to 400-500°C (the temperature here is the requirement for the nitrogen to be introduced, and it can be reduced by lowering the heating temperature of the nitrogen to reduce the heating power), and continue to pass it for 1-2 hours. Then, pass room temperature nitrogen into the furnace until the furnace temperature drops to 180-200°C, close the inlet and outlet valves; open the furnace cover 12, and cool it to room temperature. The first time hot nitrogen is passed into the furnace, on the one hand, to remove hydrogen under inert gas protection, and on the other hand, to accelerate the temperature drop while preventing the temperature from dropping too quickly. The second time room temperature nitrogen is passed into the furnace, it accelerates the temperature drop. There is no limit on the time of introduction, and the valve is closed when the temperature reaches 200°C.

[0066] Open the furnace cover to speed up the cooling process; air cooling can speed up the cooling process.

[0067] The vacuuming is to reduce the air pressure in the furnace to below 100 Pa, so as to ensure that the air atmosphere has an impact on the coating repair process.

[0068] The nitrogen and oxygen mixed gas has an oxygen content of 0.2-0.4%, which ensures that the mixed gas has a certain oxidizing property but is not too high.

[0069] The amount of hydrogen mixed in is 0.5-0.8%, which ensures that the mixed gas has a certain reducing property.

[0070] The gas heating needs to be preheated by the exhaust gas of CA (magnesium oxide nitrogen coating) and CT (insulation coating and hot stretching flattening), and then further heated by the combustion of hydrogen exhaust gas discharged from the CB (high temperature annealing) furnace, and finally heated to the corresponding temperature by radiation.

[0071] Device Example 1:

[0072] A device for improving the interlayer resistance of oriented silicon steel, comprising an air inlet branch pipe, a gas heating pipe 4, an air inlet main pipe 5, an air inlet branch pipe 6, an air outlet main pipe 11, and a heat treatment furnace; the air inlet branch pipe comprises a nitrogen air inlet branch pipe 1, a hydrogen air inlet branch pipe 2, and an oxygen air inlet branch pipe 3; the air inlet branch pipe and the air inlet branch pipe 6 are connected in sequence through the gas heating pipe 4 and the air inlet main pipe 5; the air inlet branch pipe 6 comprises a plurality of branch pipes, and the plurality of branch pipes are all arranged on the furnace wall at the air inlet end of the heat treatment furnace; the air outlet main pipe 11 is arranged on the furnace wall at the air outlet end of the heat treatment furnace; the heat treatment furnace comprises a furnace body and a furnace cover 12, and the outside of the furnace body is the furnace wall; an air flow baffle 10 and a placement rack 9 are arranged inside the furnace body; the air flow baffle 10 is vertically arranged on the furnace bottom plate, and one end of the air flow baffle 10 is in contact with the furnace wall on the air inlet side of the heat treatment furnace body; and does not contact the furnace wall on the side where the air outlet main pipe 11 is located. The furnace cover 12 is covered by the heat treatment furnace body. The air flow baffle 10 is arranged between adjacent air inlet pipes. The two ends of the heat treatment furnace are arc-shaped. The air inlet end furnace wall of the heat treatment furnace is a continuous wavy structure, and the air inlet pipe 6 is arranged in the middle of each wavy raised part; the air flow baffle 10 is arranged at the intersection of adjacent waves and on the extension line from the air inlet end to the air outlet end; the air outlet end of the heat treatment furnace is arc-shaped. The furnace wall includes an outer furnace wall 7 and an inner furnace wall 8; vacuum pumps and control valves are installed on the air inlet pipe and the air outlet pipe. The air flow baffle 10 is welded to the heat treatment furnace; the placement rack 9 is arranged on the furnace bottom plate of the heat treatment furnace; the placement rack 9 includes a base 16 inclined from high to low and a gasket 15 arranged on the base 16; the inclination angle of the base is 30°.

[0073] Device Example 2:

[0074] The device is the same as that of Example 1, except that the heat treatment furnace is not rounded (e.g. Figure 2 As shown), it is a rectangular parallelepiped structure.

[0075] Example 1

[0076] The surface micromorphology of the oriented silicon steel after CT was observed and its resistance was tested. It was found that there were a lot of cracks on the surface. The interlayer resistance in the middle of the surface was 23.5Ω·cm. 2 , the interlayer resistance of the edge is 27.3Ω·cm 2 .

[0077] Using the device of device embodiment 1, the oriented silicon steel is processed by the following method:

[0078] (1) Open the furnace cover, place the silicon steel coil in the specified direction and position, close the furnace cover, and perform vacuuming.

[0079] (2) The vacuum degree in the furnace is reduced to 68.8 Pa. The valves of nitrogen inlet branch pipe 1, oxygen inlet branch pipe 3 and outlet main pipe 11 are opened to mix nitrogen and oxygen. The oxygen-nitrogen mixed gas with 0.2% oxygen is preheated first, and then the mixed gas is heated to 650°C. Finally, the gas is introduced into the furnace and continuously introduced for 16 hours. When the mixed gas is continuously introduced, the gas flow rate is 16m 3 / h.

[0080] Close the valve of oxygen inlet branch 3, preheat and heat nitrogen, heat nitrogen to 700℃ and pass it into the furnace for 1 hour. After 1 hour, check the oxygen content in the exhaust gas, and the oxygen content is 56.7ppm. The gas flow rate of nitrogen is 18m 3 / h.

[0081] Preheat nitrogen to 750℃, open the valve of hydrogen inlet pipe 2, mix 0.5% hydrogen into the furnace, and pass it in for 4 hours. The exhaust gas is burned. The gas flow rate is 18m3. 3 / h.

[0082] Close the valve of hydrogen inlet manifold 2, preheat nitrogen to 500°C, and introduce it into the furnace for 1 hour. Close the nitrogen valve and allow the furnace to cool naturally. Once the furnace temperature drops to 200°C, open the furnace cover to accelerate the cooling process.

[0083] There is no obvious oxidation phenomenon on the surface of the oriented silicon steel. The microscopic morphology of the repaired oriented silicon steel surface is observed and its resistance is tested. It is found that there are almost no cracks on the surface of the repaired oriented silicon steel (such as Figure 5-6 As shown), and the interlayer resistance in the middle of the surface is 156.5Ω·cm 2 , the edge interlayer resistance is 304.7 cm2 The interlayer resistance in the middle part increased by 133.0Ω·cm 2 , the interlayer resistance of the edge is increased by 277.4Ω·cm 2 .

[0084] Example 2

[0085] The surface micromorphology of the CT-finished oriented silicon steel was observed, and its resistance was tested. It was found that there were a lot of cracks on the surface, and the interlayer resistance in the middle of the surface was 19.6Ω·cm. 2 , the interlayer resistance of the edge is 20.8Ω·cm 2 .

[0086] Using the device of device embodiment 1, the oriented silicon steel is processed by the following method:

[0087] (1) Open the furnace cover, place the silicon steel coil in the specified direction and position, close the furnace cover, and perform vacuuming.

[0088] (2) The vacuum degree in the furnace is reduced to 56.1 Pa. The valves of the nitrogen inlet branch pipe 1, the oxygen inlet branch pipe 3 and the outlet main pipe 11 are opened to mix nitrogen and oxygen. The oxygen-nitrogen mixed gas with 0.4% oxygen is preheated first, and then the mixed gas is heated to 7000℃. Finally, the gas is introduced into the furnace for 18 hours. When the mixed gas is continuously introduced, the gas flow rate is 20m 3 / h.

[0089] Close the valve of oxygen inlet branch 3, preheat and heat nitrogen, heat nitrogen to 750℃ and pass it into the furnace for 2 hours. After 2 hours, check the oxygen content in the exhaust gas, and the oxygen content is 56.7ppm. The gas flow rate of nitrogen is 20m 3 / h.

[0090] Preheat nitrogen to 800℃, open the valve of hydrogen inlet pipe 2, mix 0.8% hydrogen into the furnace, and pass it in for 6 hours. The exhaust gas is burned. The gas flow rate is 20m3 / min. 3 / h.

[0091] Close the valve of hydrogen inlet pipe 2, preheat nitrogen to 400°C, and introduce it into the furnace for 2 hours. Close the nitrogen valve and allow the furnace to cool naturally. Once the furnace temperature drops to 200°C, open the furnace cover to accelerate the cooling process.

[0092] There is no obvious oxidation on the surface of the oriented silicon steel. The microscopic morphology of the repaired oriented silicon steel surface is observed, and its resistance is tested. It is found that there are almost no cracks on the surface of the repaired oriented silicon steel, and the interlayer resistance in the middle of the surface is 357.8Ω·cm 2 , the interlayer resistance of the edge is 391.4cm 2 The interlayer resistance in the middle part increased by 338.2Ω·cm 2 , the interlayer resistance of the edge is increased by 370.6Ω·cm 2 .

[0093] Example 3

[0094] The surface micromorphology of the CT-finished oriented silicon steel was observed, and its resistance was tested. It was found that there were a lot of cracks on the surface, and the interlayer resistance in the middle of the surface was 30.3Ω·cm. 2 , the interlayer resistance of the edge is 24.0Ω·cm 2 .

[0095] Using the device of device embodiment 1, the oriented silicon steel is processed by the following method:

[0096] (1) Open the furnace cover, place the silicon steel coil in the specified direction and position, close the furnace cover, and perform vacuuming.

[0097] (2) The vacuum degree in the furnace is reduced to 58.6 Pa. The valves of the nitrogen inlet branch pipe 1, the oxygen inlet branch pipe 3 and the outlet main pipe 11 are opened to mix nitrogen and oxygen. The oxygen-nitrogen mixed gas with 0.3% oxygen is preheated first, and then the mixed gas is heated to 670°C. Finally, the gas is introduced into the furnace for a continuous introduction time of 17 hours. When the mixed gas is continuously introduced, the gas flow rate is 12m 3 / h.

[0098] Close the valve of oxygen inlet branch 3, preheat and heat nitrogen, heat nitrogen to 730℃ and pass it into the furnace for 1.5 hours. After 1.5 hours, check the oxygen content in the exhaust gas, and the oxygen content is 40.7ppm. The gas flow rate of nitrogen is 16m 3 / h.

[0099] Preheat nitrogen to 770℃, open the valve of hydrogen inlet pipe 2, mix 0.6% hydrogen into the furnace, and pass it through for 5 hours. The exhaust gas is burned. The gas flow rate is 16m3 / min. 3 / h.

[0100] Close the valve of hydrogen inlet manifold 2, preheat nitrogen to 450°C, and introduce it into the furnace for 1.5 hours. Close the nitrogen valve and allow the furnace to cool naturally. Once the furnace temperature drops to 200°C, open the furnace cover to accelerate the cooling process.

[0101] There is no obvious oxidation on the surface of the oriented silicon steel. The microscopic morphology of the repaired oriented silicon steel surface is observed, and its resistance is tested. It is found that there are almost no cracks on the surface of the repaired oriented silicon steel, and the interlayer resistance in the middle of the surface is 198.6Ω·cm 2 , the interlayer resistance of the edge is 284.1cm 2 The interlayer resistance in the middle part increased by 168.3Ω·cm 2 , the interlayer resistance of the edge is increased by 260.1Ω·cm 2 .

[0102] Comparative Example 1

[0103] The surface micromorphology of the oriented silicon steel after CT was observed and its resistance was tested. It was found that there were a lot of cracks on the surface. The interlayer resistance in the middle of the surface was 25.6Ω·cm. 2 , the interlayer resistance of the edge is 19.4Ω·cm2 .

[0104] Using the device of device embodiment 1, the oriented silicon steel is processed by the following method:

[0105] (1) Open the furnace cover, place the silicon steel coil in the specified direction and position, and close the furnace cover.

[0106] (2) Without vacuuming, preheat the oxygen-nitrogen mixture containing 0.3% oxygen, then heat the mixture to 670°C, and finally introduce the gas into the furnace for 16 hours.

[0107] Close the oxygen valve, preheat and heat the nitrogen, heat the nitrogen to 720℃ and pass it into the furnace for 1 hour. After 1 hour, detect the oxygen content in the exhaust gas, and the oxygen content is 76.5ppm.

[0108] Nitrogen is preheated to 780°C, mixed with 0.5% hydrogen and introduced into the furnace for 4 hours. The exhaust gas is then burned.

[0109] Close the hydrogen valve, preheat the nitrogen to 450°C, and introduce it into the furnace for 1 hour. Close the nitrogen valve and allow the furnace to cool naturally. Once the furnace temperature drops to 200°C, open the furnace cover to accelerate the cooling process.

[0110] There is a certain amount of oxidation on the surface of the oriented silicon steel. The microscopic morphology of the repaired oriented silicon steel surface was observed and its resistance was tested. It was found that there were almost no cracks on the surface of the repaired oriented silicon steel, and the interlayer resistance in the middle of the surface was 168.1Ω·cm 2 , the interlayer resistance of the edge is 176.2cm 2 The interlayer resistance in the middle part increased by 142.5Ω·cm 2 , the interlayer resistance of the edge is increased by 156.8Ω·cm 2 .

[0111] Comparative Example 2

[0112] The surface micromorphology of the oriented silicon steel after CT was observed and its resistance was tested. It was found that there were a lot of cracks on the surface. The interlayer resistance in the middle of the surface was 18.9Ω·cm. 2 , the interlayer resistance of the edge is 20.5Ω·cm 2 .

[0113] Using the device of device embodiment 1, the oriented silicon steel is processed by the following method:

[0114] (1) Open the furnace cover, place the silicon steel coil in the specified direction and position, close the furnace cover, and perform vacuuming.

[0115] (2) The vacuum degree in the furnace is reduced to 58.9 Pa, the pure nitrogen is preheated, and then the nitrogen gas is heated to 700 ° C. Finally, the nitrogen is introduced into the furnace for 18 hours.

[0116] Close the oxygen valve, preheat and heat the nitrogen, heat the nitrogen to 750℃ and pass it into the furnace for 2 hours. After 2 hours, detect the oxygen content in the exhaust gas, and the oxygen content is 13.1ppm.

[0117] Nitrogen is preheated to 800°C, mixed with 0.8% hydrogen and introduced into the furnace for 4 hours. The exhaust gas is then burned.

[0118] Close the hydrogen valve, preheat the nitrogen to 450°C, and introduce it into the furnace for 1 hour. Close the nitrogen valve and allow the furnace to cool naturally. Once the furnace temperature drops to 200°C, open the furnace cover to accelerate the cooling process.

[0119] There is no obvious oxidation on the surface of the oriented silicon steel. The microscopic morphology of the repaired oriented silicon steel surface is observed and its resistance is tested. It is found that there are very few cracks on the surface of the repaired oriented silicon steel, and the interlayer resistance in the middle of the surface is 37.4Ω·cm 2 , the interlayer resistance of the edge is 46.8cm 2 , the middle interlayer resistance increased by 8.5Ω·cm 2 , the interlayer resistance of the edge is increased by 26.3Ω·cm 2 .

[0120] Comparative Example 3

[0121] The surface micromorphology of the CT-finished oriented silicon steel was observed, and its resistance was tested. It was found that there were a lot of cracks on the surface, and the interlayer resistance in the middle of the surface was 17.9Ω·cm. 2 , the interlayer resistance of the edge is 25.2Ω·cm 2 .

[0122] Using the device of device embodiment 1, the oriented silicon steel is processed by the following method:

[0123] (1) Open the furnace cover, place the silicon steel coil in the specified direction and position, close the furnace cover, and perform vacuuming.

[0124] (2) The vacuum degree in the furnace is reduced to 56.0 Pa, and the oxygen-nitrogen mixed gas with 0.4% oxygen is preheated, and then the mixed gas is heated to 670°C, and finally the gas is introduced into the furnace for 16 hours.

[0125] Close the oxygen valve, preheat and heat the nitrogen, heat the nitrogen to 740℃ and pass it into the furnace for 1 hour. After 1 hour, detect the oxygen content in the exhaust gas, and the oxygen content is 56.7ppm.

[0126] Preheat nitrogen to 780°C and pass it into the furnace for 4 hours. Reduce the nitrogen preheat temperature to 450°C and pass it into the furnace for 1 hour. Close the nitrogen valve and let the furnace cool naturally. Once the furnace temperature drops to 200°C, open the furnace cover to accelerate the cooling rate.

[0127] The surface of the oriented silicon steel is oxidized to a certain extent. The microscopic morphology of the repaired oriented silicon steel surface is observed and its resistance is tested. It is found that there are almost no cracks on the surface of the repaired oriented silicon steel, and the interlayer resistance in the middle of the surface is 174.6Ω·cm 2 , the interlayer resistance of the edge is 266.4cm 2 The interlayer resistance in the middle part increased by 156.7Ω·cm 2 , the interlayer resistance of the edge is increased by 241.2Ω·cm 2

[0128] Comparative Example 4

[0129] The surface micromorphology of the CT-finished oriented silicon steel was observed, and its resistance was tested. It was found that there were a lot of cracks on the surface, and the interlayer resistance in the middle of the surface was 26.1Ω·cm. 2 , the edge interlayer resistance is 20.0Ω·cm 2 .

[0130] Using the device of device embodiment 1, the oriented silicon steel is processed by the following method:

[0131] (1) Open the furnace cover, place the silicon steel coil in the specified direction and position, close the furnace cover, and perform vacuuming.

[0132] (2) The vacuum degree in the furnace is reduced to 56.0 Pa, and the oxygen-nitrogen mixture mixed with 0.4% oxygen is preheated, and then the mixed gas is heated to 670°C, and finally the gas is introduced into the furnace for 4 hours.

[0133] Close the oxygen valve, preheat and heat the nitrogen, heat the nitrogen to 740℃ and pass it into the furnace for 1 hour. After 1 hour, detect the oxygen content in the exhaust gas, and the oxygen content is 56.7ppm.

[0134] Nitrogen is preheated to 780°C, mixed with 0.8% hydrogen and introduced into the furnace for 4 hours. The exhaust gas is then burned.

[0135] Close the hydrogen valve, preheat the nitrogen to 450°C, and introduce it into the furnace for 1 hour. Close the nitrogen valve and allow the furnace to cool naturally. Once the furnace temperature drops to 200°C, open the furnace cover to accelerate the cooling process.

[0136] There is no obvious oxidation phenomenon on the surface of the oriented silicon steel. The microscopic morphology of the repaired oriented silicon steel surface is observed and its resistance is tested. It is found that the surface of the repaired oriented silicon steel is almost entirely composed of a small number of cracks, and the interlayer resistance in the middle of the surface is 45.8Ω·cm 2 , the interlayer resistance of the edge is 66.4cm 2 The interlayer resistance in the middle part increased by 19.7Ω·cm 2 , the interlayer resistance of the edge is increased by 44.4Ω·cm 2 .

[0137] Comparative Example 5

[0138] The surface micromorphology of the CT-finished oriented silicon steel was observed, and its resistance was tested. It was found that there were a lot of cracks on the surface, and the interlayer resistance in the middle of the surface was 36.7Ω·cm. 2 , the interlayer resistance of the edge is 34.0Ω·cm 2 .

[0139] Using the device of device embodiment 1, the oriented silicon steel is processed by the following method:

[0140] (1) Open the furnace cover, place the silicon steel coil in the specified direction and position, close the furnace cover, and perform vacuuming.

[0141] (2) The vacuum degree in the furnace is reduced to 58.6 Pa, and the oxygen-nitrogen mixed gas with 0.3% oxygen is preheated, and then the mixed gas is heated to 370°C, and finally the gas is introduced into the furnace for 17 hours.

[0142] Close the oxygen valve, preheat and heat the nitrogen, heat the nitrogen to 430℃ and pass it into the furnace for 1.5 hours. After 1.5 hours, detect the oxygen content in the exhaust gas, and the oxygen content is 40.7ppm.

[0143] Nitrogen is preheated to 470°C, mixed with 0.6% hydrogen and introduced into the furnace for 5 hours. The exhaust gas is then burned.

[0144] Close the hydrogen valve, preheat the nitrogen to 350°C, and introduce it into the furnace for 1.5 hours. Close the nitrogen valve and allow the furnace to cool naturally. Once the furnace temperature drops to 200°C, open the furnace cover to speed up the cooling process.

[0145] There is no obvious oxidation on the surface of the oriented silicon steel. The microscopic morphology of the repaired oriented silicon steel surface is observed and its resistance is tested. It is found that there are a lot of cracks on the surface of the repaired oriented silicon steel, and the interlayer resistance in the middle of the surface is 38.1Ω·cm 2 , the interlayer resistance of the edge is 27.3cm 2 , the middle interlayer resistance increased by 1.4Ω·cm 2, the interlayer resistance at the edge decreased by 6.7Ω·cm 2 .

[0146] It can be seen from Examples 1 to 3 that when the temperature, atmosphere and holding time of the coating repair device meet the requirements, there is no obvious oxidation phenomenon on the surface of the oriented silicon steel, the cracks are almost completely eliminated, and the interlayer resistance is greatly improved.

[0147] In Comparative Example 1, the oriented silicon steel was not vacuumed before the nitrogen-oxygen mixture was introduced, and a certain amount of oxygen existed in the furnace, and oxidation occurred on the surface of the treated oriented silicon steel. In Comparative Example 2, oxygen was not introduced into the oriented silicon steel during the treatment process, and the increase in interlayer resistance of the treated oriented silicon steel was relatively small. In Comparative Example 3, hydrogen was not introduced in the later stage of the treatment, and oxidation occurred on the surface of the treated oriented silicon steel. In Comparative Example 4, the nitrogen-oxygen mixture was only treated for 4 hours, and the increase in interlayer resistance of the treated oriented silicon steel was relatively small. In Comparative Example 5, the gas heating temperature was reduced by 300°C. After treatment, a large number of cracks still existed on the surface of the oriented silicon steel, and there was no obvious change in the interlayer resistance.

[0148] from Figure 5-6 It can be seen that before treatment, the surface density is poor and there are many cracks and pores on the surface. After treatment by the present invention, the surface density is improved and the cracks and pores are greatly reduced.

[0149] In summary, in the production process of oriented silicon steel, after the coating liquid is applied, it takes no more than 1 minute to dry and sinter. The coating liquid evaporates the water in such a short time and the sintering is completed. The resulting coating will have a large number of cracks and pores, which greatly damage the interlayer resistance of the oriented silicon steel. In the present invention, the oriented silicon steel coil is subjected to a long-term high-temperature treatment, and the surface coating slowly heals at high temperature, and eventually the cracks and pores on the surface of the oriented silicon steel are greatly reduced. In addition, the insulating coating on the surface of the oriented silicon steel is not absolutely uniform, and there will be certain micro-areas that are not coated and exposed. In the present invention, 0.2-0.4% oxygen will be introduced in the initial stage, which can oxidize the micro-areas of the silicon steel matrix exposed on the surface of the oriented silicon steel, reduce the low-resistance area, and thus reduce the overall interlayer resistance of the oriented silicon steel. However, due to the extremely high tension between the silicon steel coils, it is difficult for gas to enter the middle of the coil, so a long time is required for the infiltration reaction. When oxygen enters the middle of the coil to react, the edge of the coil has already begun to overoxidize. Therefore, a certain amount of hydrogen is introduced in the later stage to reduce the edge of the coil to ensure that the plate surface does not turn yellow or red. At the same time, the coating repair line adopted by the present invention adopts a multi-coil common furnace treatment, which can process a large number of oriented silicon steel coils at one time, greatly improving production efficiency. The present invention rationally utilizes the waste gas heat generated in the production process of oriented silicon steel, performs heat treatment on the gas to be heated, and greatly saves energy waste.

[0150] The above description is merely a preferred embodiment of the present invention, and the present invention is not limited to the above embodiment. It is understood that other improvements and variations directly derived or imagined by those skilled in the art without departing from the spirit and concept of the present invention should be considered to be included in the scope of protection of the present invention.

Claims

1. A device for increasing interlayer resistance of oriented silicon steel, characterized in that: The device comprises an air intake branch pipe, a gas heating pipe (4), an air intake main pipe (5), an air intake branch pipe (6), an air outlet main pipe (11), and a heat treatment furnace; The air intake branch pipes include a nitrogen air intake branch pipe (1), a hydrogen air intake branch pipe (2), and an oxygen air intake branch pipe (3); the air intake branch pipes and the air intake branch pipes (6) are connected in sequence through the gas heating pipe (4) and the air intake main pipe (5); the air intake branch pipe (6) includes a plurality of branch pipes, and the plurality of branch pipes are all arranged on the air intake end furnace wall of the heat treatment furnace; The gas outlet main pipe (11) is arranged on the furnace wall of the gas outlet end of the heat treatment furnace; The heat treatment furnace comprises a furnace body and a furnace cover (12), the exterior of the furnace body being a furnace wall; an air flow baffle (10) and a placement rack (9) are provided inside the furnace body; the air flow baffle (10) is vertically arranged on the furnace bottom plate, and one end of the air flow baffle (10) contacts the furnace wall on the air inlet side of the heat treatment furnace body; and does not contact the furnace wall on the side where the gas outlet main pipe (11) is located; the placement rack (9) is arranged on the furnace bottom plate of the heat treatment furnace and is used to place steel coils (14); The furnace wall at the air inlet end of the heat treatment furnace is a continuous wave-shaped structure, and the air inlet branch pipe (6) is arranged at the middle position of each wave-shaped raised part; the air flow baffle (10) is arranged at the intersection of adjacent waves and on the extension line from the air inlet end to the air outlet end; the air outlet end of the heat treatment furnace is arc-shaped.

2. The device according to claim 1, characterized in that Vacuum pumps and control valves are installed on the air inlet and outlet pipes.

3. The device according to claim 1, characterized in that Both ends of the heat treatment furnace are arc-shaped.

4. The device according to claim 1, characterized in that The furnace wall comprises an outer furnace wall (7) and an inner furnace wall (8).

5. The device according to claim 1, characterized in that The air flow baffle (10) is arranged between adjacent air inlet branch pipes and is welded to the heat treatment furnace.

6. The device according to claim 1, characterized in that The placement rack (9) comprises a base (16) inclined from high to low and a gasket (15) arranged on the base (16); the inclination angle of the base is 20-35 degrees.

7. The device according to claim 6, characterized in that The inclination angle of the base is 30°.

8. A method for increasing interlayer resistance of oriented silicon steel, characterized in that: The method comprises the following steps: (1) Placing the oriented silicon steel coils (14) coated with the insulating coating onto the gaskets (15) of the placement rack (9) of the device according to any one of claims 6 to 7, closing the furnace cover (12) to ensure the sealing; and evacuating the furnace with a vacuum pump; (2) The oriented silicon steel coil is then treated by controlling the atmosphere and temperature.

9. The method according to claim 8, characterized in that In step (2), the specific process of the processing is: (2-1) Open the valves of the nitrogen inlet branch pipe (1), the oxygen inlet branch pipe (3) and the outlet main pipe (11), mix the nitrogen and oxygen and let them enter the gas heating pipe (4), heat the mixed gas with a heating device, and when the temperature reaches 650-700°C, pass the mixed gas into the furnace and continue to pass the mixed gas for 16-18 hours; (2-2) Close the valve of the oxygen inlet branch pipe (3), heat nitrogen to 700~750℃, and continuously introduce it for 1~2 hours; (2-3) After heating the nitrogen to 750-800°C, open the valve of the hydrogen inlet branch pipe (2) and introduce a mixture of nitrogen and hydrogen. Continue to introduce the mixture for 4-6 hours, and then burn the exhausted gas. (2-4) Close the valve of the hydrogen inlet branch (2), heat the nitrogen to 400~500℃, and continue to pass it for 1~2 hours. Then, pass the nitrogen at room temperature into the furnace until the temperature inside the furnace drops to 180~200℃, close the inlet valve and the outlet valve; open the furnace cover (12) and cool it to room temperature.

10. The method according to claim 9, characterized in that In step (2-1), the oxygen content in the mixed gas is 0.2~0.4%; when the mixed gas is continuously passed, the gas flow rate is 12~20m 3 / h; in step (2-2), the gas flow rate of nitrogen is 16-20m 3 / h, and the oxygen content in the atmosphere of the heat treatment furnace is less than 100ppm; in step (2-3), the hydrogen content in the mixed gas is 0.5~0.8%; the amount of hydrogen and nitrogen introduced is 16~20 m 3 / h.

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