An oriented silicon steel with excellent sheet shape and its production method

Abstract

The present invention discloses an excellent plate-shaped oriented silicon steel and a production method thereof, belonging to the technical field of oriented silicon steel production. The production method of the present invention is: first, the raw materials are subjected to ironmaking, steelmaking, hot rolling, cold rolling, decarburization, and secondary cold rolling to obtain cold-rolled steel plates; after coating the surface of the cold-rolled steel plates with magnesium oxide, they are coiled and triangular steel strips are formed to obtain semi-finished silicon steel coils; the semi-finished silicon steel coils are placed in a new heating furnace, and after heating and heat preservation, they are cooled to room temperature; then they are stretched and flattened to obtain oriented silicon steel with excellent plate shape. The present invention optimizes the packaging method, adopts a new furnace structure and cooling trough to control the flatness of the furnace bottom plate during the high-temperature annealing process, and eliminates the damage caused to the furnace bottom side by the cooling platform during cooling. The prepared oriented silicon steel plate has good flatness, is free of undesirable phenomena such as rib waves and horseshoe prints, and the yield rate of the material is increased by 5% to 10%.

Description

Technical Field

[0001] The present invention relates to the technical field of grain-oriented silicon steel production, and in particular to high-quality plate-shaped grain-oriented silicon steel and a production method thereof. Background Art

[0002] Grain-oriented electrical steel is consumed in huge quantities every year and is widely used in various fields of the national economy, such as power transformation, power generation and electricity consumption. It has high requirements for production technology, equipment, operation and on-site management, and is known as the "craft" among steel products.

[0003] In view of the increasingly tight energy situation and the urgent need for energy conservation and consumption reduction in the power industry, continuously improving its performance and reducing its iron loss have become the focus of competition and a highly concerned research topic in the silicon steel manufacturing industry.

[0004] Due to differences in production processes, the current production method for ordinary grain-oriented silicon steel mostly involves only low-temperature recovery annealing after secondary cold rolling. In addition, factors such as the structure of the furnace itself and the characteristics of the furnace floor result in uneven stress release in the steel plate. The high-temperature annealing process can easily cause stress concentration in some parts of the steel coil, resulting in horseshoe prints and rib waves in the final product, causing material waste. Major companies are also constantly researching and exploring this issue to improve the utilization rate of finished materials. Summary of the invention

[0005] To address the shortcomings of existing technologies, the present invention provides a superior flat-shaped grain-oriented silicon steel and a production method thereof. By optimizing the packaging method, employing a novel furnace platform structure and cooling troughs to control the flatness of the furnace floor during high-temperature annealing, and eliminating damage to the furnace floor caused by the cooling platform during cooling, the resulting grain-oriented silicon steel exhibits excellent flatness, free of undesirable defects such as rib ripples and horse hoof marks, and increases the yield rate by 5% to 10%.

[0006] The technical solution of the present invention is as follows:

[0007] A method for producing grain-oriented silicon steel with excellent plate shape comprises the following steps:

[0008] S1: The raw materials are subjected to ironmaking, steelmaking, hot rolling, cold rolling, decarburization, and secondary cold rolling to obtain cold-rolled steel sheets with a thickness of 0.10 to 0.35 mm;

[0009] S2: After coating the surface of the cold-rolled steel sheet with magnesium oxide, the steel sheet is coiled and formed into triangular steel strips to obtain semi-finished silicon steel coils;

[0010] S3: placing the semi-finished silicon steel coil obtained in S2 in a heating furnace, heating it, keeping it warm, and then cooling it to room temperature;

[0011] S4: Stretch and flatten to obtain oriented silicon steel with excellent plate shape.

[0012] Further, in S2, the winding is carried out by two-stage constant tension winding.

[0013] Further, the specific method of the two-stage constant tension winding is as follows: when the outer diameter ≤ 1500 mm, the winding is carried out with a tension coefficient of 1.0 - 1.2, and the winding tension value is 1600 - 1800 KG; when the outer diameter of the steel coil > 1500 mm, the winding is carried out with a tension coefficient of 1.2 - 1.4, and the winding tension value is 1800 KG - 2000 KG.

[0014] Further, in S2, the specific method of strapping is as follows: two steel straps are strapped at the positions of 1 / 3 and 2 / 3 from the bottom of the steel plate, and one steel strap is strapped at the position of 10 mm from the bottom of the steel plate, and the pressure of the strapping belt is 0.5 - 2 KG.

[0015] Further, in S3, the heating furnace includes a furnace platform bottom plate 10, a furnace platform base 11, a refractory brick layer 1, a resistance belt 2, and an exhaust pipe 3 in the furnace; a refractory brick layer 1 is provided on the furnace platform bottom plate 10; the resistance belt 2 is arranged in the space surrounded by the refractory brick layer 1, and the height of the resistance belt 2 is less than that of the refractory brick layer 1.

[0016] Further, the refractory brick layer 1 includes multiple layers of annular refractory bricks 101 distributed in a circular ring shape from the center of the furnace platform to the edge, linear refractory bricks I 102 distributed radially from the center of the furnace platform to each layer of annular refractory bricks; and linear refractory bricks II 103 distributed linearly from the first layer of annular refractory bricks to the Nth layer of annular refractory bricks, N ≥ 3; the multiple layers mean ≥ 3 layers.

[0017] Further, a base refractory brick layer 104 is laid on the bottom surface surrounded by the outermost layer of the multiple layers of annular refractory bricks 101 and the furnace platform bottom plate 10; except for the outermost layer of the multiple layers of annular refractory bricks 101, the remaining refractory bricks of the refractory brick layer 1 are arranged on the upper surface of the base refractory brick layer 104.

[0018] Further, the bottoms of the resistance belts are connected to each other; the material of the refractory brick is high-aluminum refractory brick; the resistance belt is an iron-chromium-aluminum flat belt; the width of the annular refractory brick is 40 - 70 mm; the linear refractory bricks I and II can be collectively referred to as linear refractory bricks, the width of the linear refractory brick is less than that of the annular refractory brick, and the width of the linear refractory brick is 20 - 50 mm; the height difference between the annular refractory brick and the linear refractory brick is 0 - 12 mm (the average height of the annular refractory brick minus the average height of the linear refractory brick).

[0019] The number of the annular refractory bricks and the linear refractory bricks is determined according to the size of the furnace platform and the load it bears.

[0020] Further, in S3, the cooling is to place the silicon steel coil that has been pre-cooled after heat preservation (cooled to 350°C after heat preservation) in a cooling tank for cooling to room temperature; the cooling tank includes a tank bottom, quartz sand, and high-temperature resistant cloth; the quartz sand is laid on the tank bottom of the cooling tank, and 2 to 5 layers of high-temperature resistant cloth are laid on the quartz sand; the thickness of the quartz sand is 100 to 500 mm; the high-temperature resistant cloth is a flame-retardant heat-insulating cloth; high temperature resistance means a temperature resistance of more than 800°C.

[0021] An oriented silicon steel with excellent flatness prepared by the production method.

[0022] The beneficial technical effects of the present invention are as follows:

[0023] (1) By optimizing the furnace structure and flexibly adjusting the layout position of the resistance bands according to the steel coil, the present invention makes the steel coil more uniform during heating and heat preservation, makes the cooling rate of the steel coil in each direction close, avoids the phenomenon that the local cooling rate is too large, resulting in stress concentration and deformation of the steel coil, and at the same time rearranges the refractory bricks, making the force on the entire furnace platform more uniform in the plane direction, reducing the damage of local refractory bricks due to uneven force during the use of the furnace platform, resulting in unevenness of some positions of the furnace platform, deformation of the furnace bottom plate and local stress concentration of the steel coil, etc.

[0024] (2) The present invention optimizes the packing method. After the steel coil is wound after coating with magnesium oxide, three steel belts need to be tied. Two steel belts are tied at the 1 / 3 and 2 / 3 positions from the bottom of the steel plate (the operating side edge), and one steel belt is tied at the 10 mm position at the bottom of the steel plate (the operating side edge). Since the steel coil is placed vertically, the contact position between the bottom and the bottom plate is the most stressed, and the top is the least stressed. The new packing method makes the force on the entire steel coil more balanced in the vertical direction, which can greatly reduce the uneven force caused by the unbalanced interaction between the steel coil and the steel belt during the heating, heat preservation and cooling processes due to thermal expansion and cold contraction, and avoid the deformation of the steel coil caused thereby.

[0025] (3) By optimizing the cooling method, the present invention designs a special cooling tank, so that the edge of the annealed steel coil is in soft contact with the quartz sand covered with high-temperature resistant cloth during cooling, while the traditional cooling method is that the edge of the steel coil is in direct contact with the flat surface of the cooling platform. When there is local unevenness on the end face of the steel coil, it is easy to cause stress concentration and extrusion stress at this position. When the contact surface is quartz sand and high-temperature resistant cloth, the uneven points or surfaces on the end face of the steel coil can be released into the quartz sand, eliminating the defects at the edge. Description of the Drawings

[0026] Figure 1 It is the process flow chart of the present invention.

[0027] Figure 2 It is the furnace platform structure diagram adopted by the present invention.

[0028] Figure 3 The furnace platform edge used in the present invention Figure 1 The cross-sectional view of the position shown

[0029] Figures 2 - 3 In the figure: 1, refractory brick; 2, resistance band; 3, exhaust pipe inside the furnace; 4, water outlet pipe; 5, water inlet pipe; 6, exhaust pipe outside the furnace; 7, inlet pipe; 8, water tank; 9, sealing groove; 10, furnace platform bottom plate, 11, furnace platform base; 12, furnace platform heating layer; 101, annular refractory brick; 102, linear refractory brick I; 103, linear refractory brick II; 104, base refractory brick layer

[0030] Figure 4 The structure diagram of the cooling tank adopted by the present invention

[0031] In the figure: 1, steel body tank; 2, quartz sand; 3, steel coil; 4, high-temperature resistant cloth Specific embodiments

[0032] The present invention will be specifically described below in conjunction with the accompanying drawings and embodiments

[0033] The furnace platform structure includes the layout structure of the furnace platform refractory bricks and the characteristic structure of the furnace bottom plate. Since the furnace platform is the main body for carrying the steel coil, its structure directly affects the stress distribution during the heating of the steel coil. The furnace platform structure also needs to consider the arrangement of the resistance bands to ensure the heating efficiency of the resistance bands. The furnace platform bottom plate, as the medium directly contacting the steel coil, will deform during long-term use. By optimizing the furnace platform structure, the entire furnace platform structure can be made more stable and the stress more uniform, avoiding the generation of rib waves and horseshoe marks on the steel coil

[0034] Based on the above research, the present invention relates to a method for producing high-quality grain-oriented silicon steel with excellent plate shape. The process flow chart of the present invention is as Figure 1 shown, and the specific production method includes the following steps

[0035] S1: The raw materials are processed through ironmaking, steelmaking, hot rolling, cold rolling, decarburization, and secondary cold rolling to obtain a cold-rolled steel plate with a thickness of 0.10 - 0.35 mm

[0036] S2: After coating magnesium oxide on the surface of the cold-rolled steel plate, two-stage constant tension winding is adopted, and a triangular steel belt is wound to obtain a semi-finished silicon steel coil

[0037] The specific method of the two-stage constant tension winding is as follows: When the outer diameter ≤ 1500 mm, a tension coefficient of 1.0 - 1.2 is adopted for winding, and the winding tension value is 1600 - 1800 KG; when the outer diameter of the steel coil > 1500 mm, a tension coefficient of 1.2 - 1.4 is adopted for winding, and the winding tension value is 1800 KG - 2000 KG

[0038] The specific method for tying the V-belt is as follows: Two steel belts are tied at the 1 / 3 and 2 / 3 positions from the bottom of the steel plate, and one steel belt is tied at the position 10 mm from the bottom of the steel plate. The pressure of the packing belt is 0.5 - 2 KG.

[0039] S3: Place the semi-finished silicon steel coil obtained in S2 in a heating furnace with a new structure, heat it up, keep it warm, and then cool it to room temperature; the annealed steel coil is cooled in a cooling tank to eliminate the edge defects caused by the stress concentration on the furnace bottom side.

[0040] S4: Stretch and level the obtained steel coil in an annealing furnace to obtain grain-oriented silicon steel with excellent plate shape.

[0041] In the above step S3, the outer ring of the heating furnace is a steel structure, including a furnace bottom plate 10, a furnace base 11, a furnace heating layer 12, and an exhaust pipe 3 inside the furnace; it also includes refractory bricks 1, resistance bands 2, a water tank 8, an exhaust pipe 3 inside the furnace, a water outlet pipe 4, a water inlet pipe 5, an exhaust pipe 6 outside the furnace, and a sealing groove 9; the exhaust pipe 3 inside the furnace is located inside the furnace heating layer 11 and communicates with the exhaust pipe 6 outside the furnace located below the furnace base 11; a refractory brick layer 1 is provided on the furnace bottom plate 10; the resistance bands 2 are arranged in the space surrounded by the refractory brick layer 1, and the height of the resistance bands 2 is less than that of the refractory brick layer 1.

[0042] The refractory brick layer 1 includes multiple layers of annular refractory bricks 101 distributed in a circular ring shape from the center of the furnace platform to the edge, and linear refractory bricks I 102 distributed radially from the center of the furnace platform to each layer of annular refractory bricks; the multiple layers mean ≥3 layers. The refractory brick layer 1 also includes linear refractory bricks II 103 linearly distributed from the first layer of annular refractory bricks to the Nth layer of refractory bricks, N≥3.

[0043] In S3, the heating furnace includes a furnace bottom plate 10, a furnace base 11, a refractory brick layer 1, resistance bands 2, and an exhaust pipe 3 inside the furnace; a refractory brick layer 1 is provided on the furnace bottom plate 10; the resistance bands 2 are arranged in the space surrounded by the refractory brick layer 1, and the height of the resistance bands 2 is less than that of the refractory brick layer 1.

[0044] The refractory brick layer 1 includes multiple layers of annular refractory bricks 101 distributed in a circular ring shape from the center of the furnace platform to the edge, linear refractory bricks I 102 distributed radially from the center of the furnace platform to each layer of annular refractory bricks; and linear refractory bricks II 103 linearly distributed from the first layer of annular refractory bricks to the Nth layer of annular refractory bricks, N≥3; the multiple layers mean ≥3 layers.

[0045] A base refractory brick layer 104 is laid on the bottom surface surrounded by the outermost layer of the multiple layers of annular refractory bricks 101 and the furnace bottom plate 10; except for the outermost layer of the multiple layers of annular refractory bricks 101, the other layers of refractory bricks in the refractory brick layer 1 are arranged on the upper surface of the base refractory brick layer 104.

[0046] The bottoms of the resistance bands are interconnected; the refractory bricks are made of high-aluminum refractory bricks; the resistance bands are iron-chromium-aluminum flat bands; the width of the annular refractory bricks is 40-70 mm; the width of the linear refractory bricks is less than that of the annular refractory bricks, and the width of the linear refractory bricks is 20-50 mm; the height difference between the annular refractory bricks and the linear refractory bricks is 0-12 mm (the average height of the annular refractory bricks minus the average height of the linear refractory bricks).

[0047] The quantities of the annular refractory bricks and the linear refractory bricks are determined according to the size of the furnace platform and the load it bears.

[0048] In step S3, the cooling is to place the heat-insulated silicon steel coil in a cooling tank and cool it to room temperature; the cooling tank (as Figure 4 shown) includes a tank bottom, quartz sand, and high-temperature resistant cloth; the quartz sand is laid on the tank bottom of the cooling tank, and 2-5 layers of high-temperature resistant cloth are laid on the quartz sand; the thickness of the quartz sand is 100-500 mm; the high-temperature resistant cloth is flame-retardant and heat-insulating cloth; high temperature resistance means a temperature resistance above 800 °C.

[0049] Example 1

[0050] An excellent flat-type grain-oriented silicon steel, and its preparation method includes the following steps:

[0051] S1: Prepare raw materials, and obtain a cold-rolled steel plate with a thickness of 0.2 mm through ironmaking, steelmaking, hot rolling, primary cold rolling, decarburization, and secondary cold rolling;

[0052] S2: After coating magnesium oxide on the surface of the cold-rolled steel plate, use two-stage constant-tension winding. When the outer diameter is less than or equal to 1500 mm in the first stage, a tension coefficient of 1.0 is used, and the winding tension is 1600 KG; when the outer diameter is greater than 1500 in the second stage, a tension coefficient of 1.2 is used, and the winding tension is 1800 KG.

[0053] Then, make triangular steel belts to obtain a semi-finished silicon steel coil; the making of triangular steel belts is to make two steel belts at the 1 / 3 and 2 / 3 positions from the bottom of the steel plate, and make one steel belt at the 10 mm position at the bottom of the steel plate, and the pressure of the packing belt is 0.5 KG.

[0054] S3: Subsequently, place the obtained semi-finished silicon steel coil in a heating furnace with a new structure, heat it up to 1190 °C, keep it warm for 3 h, and then cool it to room temperature; the annealed steel coil is cooled in a cooling tank to eliminate the edge defects caused by the stress concentration on the furnace bottom side.

[0055] Among them, the furnace platform structure of the heating furnace with the new structure is a "staggered" structure. The furnace platform structure is that the outer circle of the overall furnace platform is a steel structure (as Figures 2 - 3As shown in the figure, it includes a furnace platform bottom plate 10, a furnace platform base 11, a furnace platform heating layer 12, and an exhaust pipe 3 inside the furnace; it also includes refractory bricks 1, resistance bands 2, a water tank 8, an exhaust pipe 3 inside the furnace, a water outlet pipe 4, a water inlet pipe 5, an exhaust pipe 6 outside the furnace, and a sealing groove 9; the exhaust pipe 3 inside the furnace is located inside the furnace platform heating layer 11 and communicates with the exhaust pipe 6 outside the furnace located below the furnace platform base 11; a refractory brick layer 1 is provided on the furnace platform bottom plate 10; the resistance bands 2 are arranged in the space surrounded by the refractory brick layer 1, and the height of the resistance bands 2 is less than that of the refractory brick layer 1.

[0056] The refractory brick layer 1 includes 3 layers of annular refractory bricks 101 distributed in a circular ring shape from the center of the furnace platform to the edge, and linear refractory bricks I 102 distributed radially from the center of the furnace platform to each layer of annular refractory bricks and perpendicular to each other. The refractory brick layer 1 also includes 4 linear refractory bricks II 103 distributed radially from the first layer of annular refractory bricks to the third layer of annular refractory bricks. The bottom surface surrounded by the outermost layer of the 3 layers of annular refractory bricks 101 and the furnace platform bottom plate 10 is paved with a base refractory brick layer 104; except for the outermost layer of the 3 layers of annular refractory bricks 101, the rest of the refractory bricks in the refractory brick layer 1 are arranged on the upper surface of the base refractory brick layer 104. That is, refractory bricks are laid on the inner bottom of the refractory furnace, and the entire tabletop is divided into 3 blocks in a circular ring by the remaining refractory bricks, and is divided into 12 parts radially from the center to the periphery. The resistance bands are fixed on the tabletop according to the size of each gap, and the refractory bricks are laid in the Figures 2 - 3 above-mentioned manner, the resistance bands are evenly distributed in the gaps between the refractory bricks, there is a water trough around the outer circle of the steel body, and the air pipe enters from the center of the bottom. The refractory bricks divide the entire furnace platform into 12 equal parts radially, the width of the annular refractory bricks is 50 mm; the width of the linear refractory bricks is less than that of the annular refractory bricks, and the width of the linear refractory bricks is 40 mm; the height difference between the annular refractory bricks and the linear refractory bricks is 12 mm.

[0057] The heat-insulated semi-finished silicon steel product is taken out of the heating furnace and placed in the cooling tank to cool to room temperature.

[0058] The cooling tank includes a tank bottom, quartz sand, and a flame-retardant heat-insulating cloth with a temperature resistance of 800 °C; the quartz sand is laid on the tank bottom of the cooling tank, and 2 layers of high-temperature-resistant cloth are laid on the quartz sand, and the thickness of the quartz sand is 100 mm.

[0059] S4: The cooled steel coil is further subjected to stretching and leveling, hot stretching and leveling, and then wound to obtain a silicon steel coil with an excellent plate shape. The width of the defective part at the side of the furnace bottom is 30 mm, the length of the defective part at the head is 80 meters, and the iron loss is 1.05 W / KG.

[0060] Example 2

[0061] An excellent plate-shaped grain-oriented silicon steel, and its preparation method includes the following steps:

[0062] S1: Prepare raw materials, and obtain cold-rolled steel sheets with a thickness of 0.23 mm through ironmaking, steelmaking, hot rolling, primary cold rolling, decarburization, and secondary cold rolling;

[0063] S2: After coating magnesium oxide on the surface of the cold-rolled steel sheet, use two-stage constant tension winding. When the outer diameter is less than or equal to 1500 mm in the first stage, use a tension coefficient of 1.2, and the winding tension is 1800 KG; when the outer diameter is greater than 1500 in the second stage, use a tension coefficient of 1.4, and the winding tension is 2000 KG.

[0064] Then punch triangular steel belts to obtain semi-finished silicon steel coils; the punching of triangular belts is to punch two steel belts at the 1 / 3 and 2 / 3 positions from the bottom of the steel sheet, and pack one steel belt at the 10 mm position at the bottom of the steel sheet, and the pressure of the packing belt is 2.0 KG.

[0065] S3: Subsequently, place the obtained semi-finished silicon steel coils in a heating furnace with a new structure, heat up, keep warm, and then cool to room temperature; the annealed steel coils are cooled in a cooling tank to eliminate the edge defects caused by stress concentration on the bottom side of the furnace.

[0066] Among them, the furnace platform structure of the heating furnace with the new structure is a "staggered" structure. The specific structure is the same as that of the embodiment, except that the refractory bricks divide the entire furnace platform into 12 equal parts along the radial direction, the width of the annular refractory bricks is 70 mm; the width of the linear refractory bricks is less than that of the annular refractory bricks, and the width of the linear refractory bricks is 50 mm; the height difference between the annular refractory bricks and the linear refractory bricks is 0 mm.

[0067] After the heat preservation, the semi-finished silicon steel is taken out of the heating furnace and placed in the cooling tank to cool to room temperature.

[0068] The cooling tank floor includes a tank bottom, quartz sand, and a flame-retardant heat-insulating cloth resistant to 800 °C; the quartz sand is laid on the tank bottom of the cooling tank, and 5 layers of high-temperature-resistant cloth are laid on the quartz sand, and the thickness of the quartz sand is 500 mm.

[0069] S4: After the cooled steel coils are further subjected to stretch leveling and hot stretch leveling, and then wound, silicon steel coils with excellent plate shapes are obtained, the width of the edge defects is 20 mm, the length of the head defects is 50 meters, and the iron loss is 1.03 W / KG

[0070] Example 3

[0071] A kind of oriented silicon steel with excellent plate shape, and its preparation method includes the following steps:

[0072] S1: Prepare raw materials, and obtain cold-rolled steel sheets with a thickness of 0.27 mm through ironmaking, steelmaking, hot rolling, primary cold rolling, decarburization, and secondary cold rolling;

[0073] S2: After coating magnesium oxide on the surface of the cold-rolled steel plate, two-stage constant-tension winding is adopted. In the first stage, when the outer diameter is less than or equal to 1500 mm, a tension coefficient of 1.15 is used, and the winding tension is 1700 KG; in the second stage, when the outer diameter is greater than 1500, a tension coefficient of 1.25 is used, and the winding tension is 1900 KG.

[0074] Then, a triangular steel strip is applied to obtain a semi-finished silicon steel coil; the application of the triangular steel strip is to apply two steel strips at the 1 / 3 and 2 / 3 positions from the bottom of the steel plate, and pack one steel strip at the 10 mm position at the bottom of the steel plate, and the pressure of the packing belt is 1.0 KG.

[0075] S3: Subsequently, the obtained semi-finished silicon steel coil is placed in a heating furnace with a new structure, heated up, kept warm and then cooled to room temperature; the annealed steel coil is cooled in a cooling tank to eliminate the edge defects caused by the stress concentration on the bottom side of the furnace.

[0076] Among them, the furnace platform structure of the heating furnace with the new structure is a "staggered" structure. The specific structure is the same as that of the embodiment, except that the refractory bricks divide the entire furnace platform into 12 equal parts along the radial direction, the width of the annular refractory brick is 70 mm; the width of the linear refractory brick is less than that of the annular refractory brick, and the width of the linear refractory brick is 50 mm; the height difference between the annular refractory brick and the linear refractory brick is 8 mm.

[0077] After being kept warm, the semi-finished silicon steel is taken out of the heating furnace and placed in a cooling tank to be cooled to room temperature.

[0078] The cooling tank is paved with a tank bottom, quartz sand, and a high-temperature resistant cloth with a temperature resistance of 800 °C; the quartz sand is laid on the bottom of the cooling tank, and 4 layers of flame-retardant heat-insulating cloth are laid on the quartz sand, and the thickness of the quartz sand is 350 mm.

[0079] S4: The cooled steel coil is further subjected to stretch leveling and hot stretch leveling, and after winding, a silicon steel coil with excellent plate shape is obtained, the width of the edge defect is 38 mm, the length of the head defect is 95 meters, and the iron loss is 1.06 W / KG.

[0080] Example 4

[0081] An oriented silicon steel with excellent plate shape, its preparation method includes the following steps:

[0082] S1: Prepare raw materials, and obtain a cold-rolled steel plate with a thickness of 0.30 mm through ironmaking, steelmaking, hot rolling, primary cold rolling, decarburization, and secondary cold rolling;

[0083] S2: After coating magnesium oxide on the surface of the cold-rolled steel plate, two-stage constant-tension winding is adopted. In the first stage, when the outer diameter is less than or equal to 1500 mm, a tension coefficient of 1.17 is used, and the winding tension is 1750 KG; in the second stage, when the outer diameter is greater than 1500, a tension coefficient of 1.23 is used, and the winding tension is 1850 KG.

[0084] Then, a semi-finished silicon steel coil is obtained by applying triangular steel belts; the application of triangular steel belts means applying two steel belts at the 1 / 3 and 2 / 3 positions from the bottom of the steel plate, and applying one steel belt at the 10 mm position from the bottom of the steel plate, with the pressure of the packing belt being 1.3 KG.

[0085] S3: Subsequently, the obtained semi-finished silicon steel coil is placed in a heating furnace with a new structure, heated, held at a constant temperature, and then cooled to room temperature; the annealed steel coil is cooled in a cooling tank to eliminate the edge defects caused by the stress concentration on the furnace bottom side.

[0086] Among them, the furnace platform structure of the heating furnace with the new structure is a "staggered" structure. The specific structure is the same as that of the embodiment, except that the refractory bricks divide the entire furnace platform into 12 equal parts along the radial direction, the width of the annular refractory brick is 50 mm; the width of the linear refractory brick is less than that of the annular refractory brick, and the width of the linear refractory brick is 20 mm; the height difference between the annular refractory brick and the linear refractory brick is 8 mm.

[0087] After being held at a constant temperature, the semi-finished silicon steel is taken out of the heating furnace and placed in the cooling tank to be cooled to room temperature.

[0088] The cooling tank itself is a steel structure, and the cooling tank includes a tank bottom, quartz sand, and a high-temperature resistant cloth (flame retardant and heat insulating cloth) with a temperature resistance of 800 °C; the quartz sand is laid on the bottom of the cooling tank, and 3 layers of flame retardant and heat insulating cloth are laid on the quartz sand, and the thickness of the quartz sand is 280 mm.

[0089] S4: After cooling, the steel coil is further subjected to stretch leveling and hot stretch leveling, and after winding, a silicon steel coil with excellent plate shape is obtained, with the width of the edge defect being 36 mm, the length of the head defect being 87 m, and the iron loss being 1.03 W / KG

[0090] Comparative Example 1

[0091] It is the same as Example 1, except that the winding tension is maintained at 1.0 throughout the winding process.

[0092] Comparative Example 2

[0093] It is the same as Example 2, except that two packing belts are used for packing, and the packing pressure is 9 kg.

[0094] Comparative Example 3

[0095] It is the same as Example 3, except that the traditional furnace platform structure is used, and the "staggered" furnace platform structure is not adopted.

[0096] Comparative Example 4

[0097] It is the same as Example 4, except that the cooling in the cooling tank is not adopted.

[0098] Test Example:

[0099] The grain-oriented electrical steel prepared in Examples 1-4 and Comparative Examples 1-4 was uncoiled for production, and the width of edge defects and the length of head defects were measured. The measurement results are shown in Table 1.

[0100] Table 1

[0101] Example Width of edge defect (mm) Length of head defect (m) Iron loss (W / KG) Example 1 30 80 1.05 Example 2 20 50 1.03 Example 3 38 95 1.06 Example 4 36 87 1.03 Comparative Example 1 45 350 1.09 Comparative Example 2 49 550 1.08 Comparative Example 3 66 890 1.10 Comparative Example 4 58 770 1.11

[0102] As can be seen from Table 1: After changing the coiling tension in Comparative Example 1 compared with Example 1, the width of edge defects increased from 30 mm in Example 1 to 45 mm, and the length of head defects increased from 80 m to 350 m; after changing the packing method in Comparative Example 2, compared with Example 2, the width of edge defects increased from 20 mm in Example 2 to 49 mm, and the length of head defects increased from 50 m to 550 m; in Comparative Example 3, the "staggered" furnace structure described in the present invention was not adopted, and the bottom structure was extremely easy to deform, resulting in uneven stress on the steel coil during heating and significant increases in the width of edge defects and the length of head defects. However, through process optimization and the design of the "staggered" furnace structure in Example 3 of the present invention, the width of edge defects and the length of head defects were greatly reduced, and the material utilization rate was increased by 5% - 10%. Due to the more uniform distribution of the resistance bands, the performance of the entire steel coil during heating was more stable, and the iron loss performance was improved by about 3% compared with the original. In Comparative Example 4, the cooling tank was not adopted, resulting in a significant increase in iron loss.

[0103] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification is only to illustrate the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed.

Claims

1. A production method of grain-oriented silicon steel with excellent sheet shape, characterized in that, The production method includes the following steps: S1: Obtain a cold-rolled steel sheet with a thickness of 0.10 - 0.35 mm by smelting iron, steelmaking, hot rolling, cold rolling, decarburization, and secondary cold rolling of raw materials; S2: After coating magnesium oxide on the surface of the cold-rolled steel sheet, wind it up, and tie triangular steel belts to obtain a semi-finished silicon steel coil; S3: Place the semi-finished silicon steel coil obtained in S2 in a heating furnace, heat it up, keep it warm, and then cool it to room temperature; S4: Stretch and level it to obtain grain-oriented silicon steel with excellent sheet shape; In S2, when the outer diameter ≤ 1500 mm, use a tension coefficient of 1.0 - 1.2 for winding, and the winding tension value is 1600 - 1800 KG; when the outer diameter of the steel coil > 1500 mm, use a tension coefficient of 1.2 - 1.4 for winding, and the winding tension value is 1800 KG - 2000 KG; The specific method of tying the triangular steel belts is: Tie two steel belts at the 1 / 3 and 2 / 3 positions from the bottom of the steel sheet, and tie one steel belt at the 10 mm position from the bottom of the steel sheet. The pressure of the packing belt is 0.5 - 2 KG; In S3, the heating furnace includes a furnace platform bottom plate (10), a furnace platform base (11), a refractory brick layer (1), a resistance belt (2), and an exhaust pipe in the furnace (3); A refractory brick layer (1) is provided on the furnace platform bottom plate (10); The resistance belt (2) is arranged in the space surrounded by the refractory brick layer (1), and the height of the resistance belt (2) is less than that of the refractory brick layer (1); The refractory brick layer (1) includes multiple layers of annular refractory bricks (101) distributed in a circular ring shape from the center of the furnace platform to the edge, linear refractory bricks I (102) distributed radially from the center of the furnace platform to each layer of annular refractory bricks; And linear refractory bricks II (103) distributed linearly from the first layer of annular refractory bricks to the Nth layer of annular refractory bricks, N ≥ 3; The multiple layers mean ≥ 3 layers.

2. The production method according to claim 1, characterized in that, A base refractory brick layer (104) is laid on the bottom surface surrounded by the outermost layer of the multiple layers of annular refractory bricks (101) and the furnace platform bottom plate (10); Except for the outermost layer of the multiple layers of annular refractory bricks (101), the other layers of refractory bricks of the refractory brick layer (1) are arranged on the upper surface of the base refractory brick layer (104).

3. The production method according to claim 1, characterized in that The height difference between the annular refractory brick and the linear refractory brick is 0 - 12 mm; The number of the annular refractory bricks and the linear refractory bricks is determined according to the size of the furnace platform and the load it bears.

4. The production method according to claim 1, characterized in that, In S3, the cooling is to place the silicon steel coil after heat preservation in a cooling tank and cool it to room temperature; The cooling tank includes a tank bottom, quartz sand, and high-temperature resistant cloth; The quartz sand is laid on the bottom of the cooling tank, and 2 - 5 layers of high-temperature resistant cloth are laid on the quartz sand; The thickness of the quartz sand is 100 - 500 mm; The high-temperature resistant cloth is a flame-retardant and heat-insulating cloth; High temperature resistance means a temperature resistance of more than 800 °C.

5. Grain-oriented silicon steel with excellent sheet shape prepared by the production method according to any one of claims 1 - 4.

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