Preparation method of high-strength ultra-wide titanium screen plate

Abstract

The invention provides a preparation method of a high-strength ultra-wide titanium screen plate. The preparation method comprises the following steps: S1, preparing raw materials; a titanium coil with the tensile strength being smaller than or equal to 420 Mpa, the thickness being 0.5-1.5 mm, the width being 680-1530 mm, the piece weight being smaller than or equal to 5 tons and the inner diameter being 508 mm or 608 mm is selected; s2, performing pretreatment; s3, punching and net pulling; punching, net pulling and shearing are conducted on a metal net pulling machine; s4, flattening is conducted; the titanium mesh is placed on a flattening machine to be subjected to multi-pass flattening; s5, softening treatment; s6, flattening is conducted; the titanium mesh is leveled through a 23-roller leveler, the front face and the back face of the titanium mesh are leveled in the width direction, and then the front face and the back face of the titanium mesh are leveled in the length direction. The high-strength ultra-wide titanium screen plate with the thickness being 0.5-1.5 mm and the width being 650-1500 mm is prepared, the unevenness of the titanium screen plate is smaller than or equal to 10 mm / m, and the requirements of emerging industries for large-specification and high-strength titanium screen plates are met to a certain extent.

Description

Technical Field

[0001] The invention relates to the technical field of nonferrous metal processing, and in particular to a method for preparing a high-strength ultra-wide titanium mesh plate. Background Art

[0002] Titanium and titanium alloys are often made into titanium mesh filter elements, titanium filter discs, titanium mesh anodes, titanium current collecting meshes, titanium shielding meshes and other products in industry due to their good acid and alkali resistance, high temperature resistance, wear resistance, high electrical and thermal conductivity, and easy forming. They are widely used in chlor-alkali, hydrometallurgy, electrochemistry, biomedicine and other fields. The processing of titanium mesh mainly includes several processing methods such as titanium wire weaving, punching, stamping and stretching. However, due to the difficult processing characteristics of titanium itself, titanium wires below Φ6mm require multiple drawing processes, and the raw materials are expensive, resulting in a high cost of titanium mesh made by the weaving method. The punching method mainly uses titanium plates as raw materials. In the stamping process, more scraps are formed, resulting in low material utilization, which further increases production costs. The stamping and stretching method can use titanium coils and titanium plates as raw materials. It not only has a high yield rate, but also high processing efficiency. It is the mainstream method for titanium mesh forming. Due to the high specific strength, poor plasticity and easy rebound of titanium, the mesh is prone to breakage and deformation during the mesh drawing process. Therefore, the current stamping and stretching method is limited to TA1 pure titanium with a tensile strength below 300Mpa. The plate shape is generally above 10-50mm / m, and the thickness is generally 0.8-1.0mm, and the width is below 650mm. There are great limitations in both the requirements for raw materials and the size range of finished products. However, with the continuous upgrading and iteration of application equipment, and the rapid development of titanium in emerging fields such as lithium extraction from salt lakes and PEM hydrogen production, the traditional low-strength and small size can no longer meet the demand. Therefore, the invention of a high-strength ultra-wide titanium mesh is of great significance to supporting the rapid development of the current emerging industries.

[0003] The prior art with publication number CN111806719A discloses a microporous copper mesh for lightning protection and a preparation method thereof, comprising the following steps: a. adjusting the punching amount of the upper mold, the spacing between the upper and lower mold sections and the lateral displacement of the upper mold of the metal mesh machine; b. passing the copper foil between the upper and lower molds and punching and shearing it into a copper mesh through the upper mold; c. placing a pressure rod on the surface of the copper mesh to apply tension to the copper mesh and stretch it; b. flattening the copper mesh; the prior art is only used to prepare copper mesh. Compared with copper mesh, titanium has high strength, poor plasticity and easy rebound. The mesh is prone to breakage and deformation during the mesh drawing process. Therefore, it is difficult for the prior art to achieve the preparation of high-strength ultra-wide titanium mesh plates, and the unevenness reaches less than 10 mm / m. Summary of the invention

[0004] In view of this, the present invention aims to propose a method for preparing a high-strength ultra-wide titanium mesh plate to solve the problem that the existing technology is only used to prepare copper mesh. Compared with copper mesh, titanium has high strength, poor plasticity, easy rebound, and easy mesh breakage and deformation during the mesh drawing process. Therefore, it is difficult to achieve the preparation of high-strength ultra-wide titanium mesh plates with unevenness below 10mm / m in the existing technology.

[0005] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0006] A method for preparing a high-strength ultra-wide titanium mesh plate comprises the following steps:

[0007] S1: Raw material preparation; select titanium coils with tensile strength ≤420Mpa, thickness 0.5~1.5mm, width 680~1530mm, unit weight ≤5 tons, and inner diameter 508mm or 608mm;

[0008] S2: pre-processing;

[0009] S3: Punching and mesh drawing: Punching, mesh drawing and shearing are performed on the metal mesh drawing machine;

[0010] S4: Flattening: Place the titanium mesh on a flattening machine for multiple passes of flattening;

[0011] S5: softening treatment;

[0012] S6: Leveling: Use a 23-roller leveling machine to level the titanium mesh, first leveling the front and back sides along the width direction, and then leveling the front and back sides along the length direction.

[0013] The present invention prepares a high-strength ultra-wide titanium mesh plate with a thickness of 0.5-1.5 mm and a width of 650-1500 mm, and the unevenness of the titanium mesh plate is ≤10 mm / m, which to a certain extent meets the needs of emerging industries for large-size, high-strength titanium mesh plates.

[0014] Furthermore, in step S1 , the titanium coil is in an annealed state.

[0015] Furthermore, in step S2, the pretreatment process is to apply lubricant to the upper and lower surfaces of the titanium coil after automatic unwinding and tape threading.

[0016] This setting can reduce die wear and improve the tensile deformation ability of the titanium coil.

[0017] Furthermore, in step S3, the net drawing speed is 6 to 10 mm / s, and the tensile deformation rate is 40 to 60%.

[0018] This setting is to prevent the titanium mesh from breaking or deforming.

[0019] Furthermore, in step S3, the short pitch size of the mesh of the stretched net is 3 to 6 mm, and the long pitch size is 6 to 12.5 mm.

[0020] Furthermore, in step S4, 3 to 10 passes of flattening are adopted in the length direction, the pressure of each pass is 300 to 400 tons, the deformation of a single pass is controlled within 10%, and the total deformation rate is 35 to 55%.

[0021] This setting is required to prevent the titanium mesh plate from deformation and breakage, while also improving the flatness of the titanium mesh plate.

[0022] Furthermore, in step S5, the softening process further comprises the following steps:

[0023] S51, pickling;

[0024] S52, drying;

[0025] S53: Annealing treatment.

[0026] On the one hand, this setting removes grease on the surface of the titanium mesh plate to prevent the grease from affecting the accuracy of leveling. On the other hand, it can reduce the hardness and strength of the titanium alloy and improve its plasticity, thereby making the titanium mesh plate easier to deform during the leveling process and improving the flatness of the titanium mesh plate.

[0027] Furthermore, the specific pickling process of step S51 is that the volume ratio of the pickling acid solution is HF:HNO3:water=2:3:5, wherein the concentrations of HF and HNO3 are both 40-63%.

[0028] Furthermore, the specific drying parameter of step S52 is that the drying temperature is 40-80°C.

[0029] Furthermore, the specific process of the annealing treatment in step S53 is that the annealing temperature is 750-800° C. and the online walking speed is 2-10 m / min.

[0030] The annealing treatment of this setting can reduce the hardness and strength of the titanium alloy and improve its plasticity, thereby making the titanium mesh plate easier to deform during the leveling process and improving the flatness of the titanium mesh plate.

[0031] Furthermore, the specific parameters of leveling in step S6 are: in the width direction, leveling is performed on both sides in 2 to 5 passes; in the length direction, leveling is performed on both sides in 3 to 6 passes, and the leveling pressure for each pass is 3 to 5 tons.

[0032] This setting is required to prevent the titanium mesh plate from deformation and breakage, while also improving the flatness of the titanium mesh plate.

[0033] Further, in step S6, the unevenness after leveling is ≤10 mm / m.

[0034] Compared with the prior art, the method for preparing a high-strength ultra-wide titanium mesh plate described in the present invention has the following advantages:

[0035] (1) The present invention prepares a high-strength ultra-wide titanium mesh plate with a thickness of 0.5 to 1.5 mm and a width of 650 to 1500 mm, and the unevenness of the titanium mesh plate is ≤10 mm / m, which to a certain extent meets the demand of emerging industries for large-size, high-strength titanium mesh plates;

[0036] (2) In the preparation method of the present invention, by controlling the flattening parameters, on the one hand, the strength of the titanium mesh plate is ensured while the flatness of the titanium mesh plate is improved, and on the other hand, initial defects that may be generated in the preparation process of the titanium mesh plate, such as tiny cracks, bubbles, etc., are eliminated;

[0037] (3) In the preparation method of the present invention, by controlling the leveling parameters, the tiny unevenness in the titanium mesh plate is further eliminated to achieve a higher flatness standard, and at the same time, the internal stress generated during the preparation of the titanium mesh plate is released to avoid cracking and deformation of the titanium alloy, thereby ensuring product quality;

[0038] (4) In the preparation method of the present invention, by arranging a softening treatment between flattening and leveling, on the one hand, grease on the surface of the titanium mesh plate is removed to prevent the grease from affecting the accuracy of leveling; on the other hand, the softening treatment can reduce the hardness and strength of the titanium alloy and improve its plasticity, thereby making the titanium mesh plate easier to deform during the leveling process and improving the flatness of the titanium mesh plate.

[0039] (5) The present invention breaks the conventional requirements of high purity and low strength of drawn mesh titanium coils, which is conducive to reducing the dependence of drawn mesh coils on high-quality sponge titanium raw materials, reducing the cost of titanium coils, and is universally applicable to pure titanium;

[0040] (6) The present invention adopts conventional production equipment, has a simple process, can produce large single-weight titanium rolls, has high production efficiency, and can realize mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is an appearance diagram of the titanium mesh plate of Example 1 of the present invention;

[0042] Figure 2 This is an appearance diagram of a titanium mesh plate according to Example 2 of the present invention;

[0043] Figure 3 This is an appearance diagram of a titanium mesh plate according to Example 3 of the present invention;

[0044] Figure 4 This is an appearance diagram of the titanium mesh plate of Example 4 of the present invention.

[0045] Figure 5 This is an appearance diagram of the titanium mesh plate of Comparative Example 1 of the present invention;

[0046] Figure 6 This is an appearance diagram of the titanium mesh plate of Comparative Example 2 of the present invention;

[0047] Figure 7 This is an appearance diagram of the titanium mesh plate of Comparative Example 3 of the present invention;

[0048] Figure 8 It is a structural schematic diagram of the titanium mesh plate of the present invention. DETAILED DESCRIPTION

[0049] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0050] Example 1

[0051] Step 1: Raw material preparation: According to the finished product size design and the diameter of the uncoiler sleeve, the pure titanium strip coil is hoisted and loaded. The grade is TA1, the state is annealed, the tensile strength is 355Mpa, the specification size is 1.0*710*L, the single weight of the titanium coil is 4.2 tons, and the inner diameter of the titanium coil is 610mm.

[0052] Continuing from the previous step, the second step is pretreatment: according to the mesh size requirements of the finished plate, a punching die is selected. After the titanium coil is automatically unrolled and threaded, a lubricant is applied to the upper and lower surfaces of the titanium coil through an online oil brush roller. The lubricant is made of refined mineral oil as a base oil and functional additives are added. Preferably, the model of the lubricant is KCL-015. This setting can reduce die wear and improve the tensile deformation capacity of the titanium coil.

[0053] Continuing from the previous step, the third step is punching and mesh drawing: punching, mesh drawing, and shearing are performed on the metal mesh drawing machine. The mesh drawing speed is 8mm / s, the mesh size is 4 (short pitch b)*8mm (long pitch a), and the tensile deformation rate is 50%. After mesh drawing, the material is automatically cut and cut in length according to the preset size.

[0054] Continuing from the previous step, the fourth step is flattening: flatten a single titanium mesh on a flattening machine, adjust the pressure roller, and flatten it three times along the length direction. The pressure of each pass is 350 tons, the deformation of a single pass is controlled within 10%, and the total deformation rate is 45%.

[0055] Continuing from the previous step, the fifth step is softening treatment: pickling and drying the flattened plate mesh, where the volume ratio of the acid solution is HF: HNO3: water = 2:3:5, the concentration of HF is 40%, the concentration of HNO3 is 55%, and the drying temperature is 40°C. The purpose of this setting is to remove surface grease. After that, argon protection continuous annealing softening treatment is carried out, the annealing temperature is 780°C, and the online walking speed is 3m / min. This setting can reduce the hardness and strength of titanium alloy and improve its plasticity, so that the titanium mesh plate is easier to deform during the leveling process and improve the flatness of the titanium mesh plate.

[0056] Continuing from the previous step, the sixth step is leveling: use a 23-roller leveling machine to level the plate mesh, first leveling it 3 times on both sides along the width direction, and then leveling it 5 times on both sides along the length direction, with a leveling pressure of 3.5 tons per leveling.

[0057] Continuing from the previous step, the seventh step, sizing: After leveling, use a shearing machine to perform bilateral precision sizing according to the preset size to prepare a 1.0*692*L finished mesh plate, see Figure 1 shown.

[0058] Example 2

[0059] Step 1: Raw material preparation: According to the finished product size design and the diameter of the uncoiler sleeve, the pure titanium strip coil is hoisted and loaded. The grade is TA1, the state is annealed, the tensile strength is 321Mpa, the specification size is 0.8*1530*L, the single weight of the titanium coil is 5.0 tons, and the inner diameter of the titanium coil is 610mm.

[0060] Following the previous step, the second step is pretreatment. According to the mesh size requirements of the finished plate, a punching die is selected. After the titanium coil is automatically unrolled and threaded, a lubricant is applied to the upper and lower surfaces of the titanium coil by an online oil brush roller. The lubricant is made of refined mineral oil as a base oil and functional additives are added. Preferably, the model of the lubricant is KCL-015, which can reduce die wear and improve the tensile deformation capacity of the titanium coil.

[0061] Continuing from the previous step, the third step is punching and mesh drawing: punching, mesh drawing and shearing are performed on the metal mesh drawing machine. The mesh drawing speed is 6mm / s, the mesh size is 3*6mm, and the tensile deformation rate is 40%. After mesh drawing, the material is automatically cut and cut in length according to the preset size.

[0062] Continuing from the previous step, the fourth step is flattening: flatten a single titanium mesh on a flattening machine, adjust the pressure roller, and flatten it 4 times along the length direction. The pressure of each pass is 400 tons. The deformation of a single pass is controlled within 10%, and the total deformation rate is 35%.

[0063] Continuing from the previous step, the fifth step is softening treatment: pickling and drying the flattened plate mesh, where the volume ratio of the acid solution is HF: HNO3: water = 2:3:5, the concentration of HF is 40%, the concentration of HNO3 is 55%, and the drying temperature is 60°C. The purpose of this setting is to remove surface grease. After that, argon protection continuous annealing softening treatment is carried out, the annealing temperature is 750°C, and the online walking speed is 5m / min. This setting can reduce the hardness and strength of titanium alloy and improve its plasticity, so that the titanium mesh plate is easier to deform during the leveling process and improve the flatness of the titanium mesh plate.

[0064] Continuing from the previous step, the sixth step is leveling: use a 23-roller leveling machine to level the plate mesh, first leveling it 4 times on both sides along the width direction, and then leveling it 5 times on both sides along the length direction, with a leveling pressure of 5 tons per time.

[0065] Continuing from the previous step, the seventh step, sizing: After leveling, use a shearing machine to perform bilateral precision sizing according to the preset size to prepare a 0.8*1500*L finished mesh plate, see Figure 2 shown.

[0066] Example 3

[0067] Step 1: Raw material preparation: According to the finished product size design and the diameter of the uncoiler sleeve, the pure titanium strip coil is hoisted and loaded. The grade is GR2, the state is annealed, the tensile strength is 365Mpa, the specification size is 0.5*1030*L, the single weight of the titanium coil is 3.5 tons, and the inner diameter of the titanium coil is 610mm.

[0068] Continuing from the previous step, the second step is pretreatment: according to the mesh size requirements of the finished plate, a punching die is selected. After the titanium coil is automatically unrolled and threaded, the lubricant is applied to the upper and lower surfaces of the titanium coil through an online oil brush roller. The lubricant uses refined mineral oil as the base oil and is configured with functional additives. The model of the lubricant is KCL-015.

[0069] Continuing from the previous step, the third step is punching and mesh drawing: punching, mesh drawing and shearing are performed on the metal mesh drawing machine. The mesh drawing speed is 8mm / s, the mesh size is 4*8mm, and the tensile deformation rate is 45%. After mesh drawing, the material is automatically cut and cut in length according to the preset size.

[0070] Continuing from the previous step, the fourth step is flattening: flatten a single titanium mesh on a flattening machine, adjust the pressure roller, and flatten it 5 times along the length direction. The pressure of each pass is 350 tons, the deformation of a single pass is controlled within 10%, and the total deformation rate is 40%.

[0071] Continuing from the previous step, the fifth step is softening treatment: pickling and drying the flattened plate mesh, where the volume ratio of the acid solution is HF: HNO3: water = 2:3:5, the concentration of HF is 55%, the concentration of HNO3 is 63%, and the drying temperature is 60°C. The purpose of this setting is to remove surface grease. After that, argon protection continuous annealing softening treatment is carried out, the annealing temperature is 780°C, and the online walking speed is 10m / min.

[0072] Continuing from the previous step, the sixth step is leveling: Use a 23-roller leveling machine to level the plate mesh. First, perform 2 passes of leveling on both sides along the width direction, and then perform 3 passes of leveling on both sides along the length direction. The leveling pressure for each pass is 3.5 tons.

[0073] Continuing from the previous step, the seventh step, sizing: After leveling, use the shearing machine to perform bilateral precision sizing according to the preset size to prepare a 0.5*1000*L finished mesh plate, see Figure 3 shown.

[0074] Example 4

[0075] Step 1: Raw material preparation: According to the finished product size design and the diameter of the uncoiler sleeve, the pure titanium strip coil is hoisted and loaded. The grade is TA2, the state is annealed, the tensile strength is 420Mpa, the specification size is 1.5*680*L, the single weight of the titanium coil is 2.5 tons, and the inner diameter of the titanium coil is 508mm.

[0076] Continuing from the previous step, the second step is pretreatment: according to the mesh size requirements of the finished plate, a punching die is selected. After the titanium coil is automatically unrolled and threaded, in order to reduce die wear and improve the tensile deformation capacity of the titanium coil, a lubricant is applied to the upper and lower surfaces of the titanium coil through an online oil brush roller. The lubricant uses refined mineral oil as a base oil and is configured with functional additives. Preferably, the model of the lubricant is KCL-015.

[0077] Continuing from the previous step, the third step is punching and mesh drawing: punching, mesh drawing and shearing are performed on the metal mesh drawing machine. The mesh drawing speed is 10mm / s, the mesh size is 6*12.5mm, and the tensile deformation rate is 60%. After mesh drawing, the material is automatically cut and cut in length according to the preset size.

[0078] Continuing from the previous step, the fourth step is flattening: flatten a single titanium mesh on a flattening machine, adjust the pressure roller, and flatten it 10 times along the length direction. The pressure of each pass is 300 tons, the deformation of a single pass is controlled within 10%, and the total deformation rate is 55%.

[0079] Continuing from the previous step, the fifth step is softening treatment: pickling and drying the flattened plate mesh, where the volume ratio of the acid solution is HF: HNO3: water = 2:3:5, the concentration of HF is 40%, the concentration of HNO3 is 63%, and the drying temperature is 80°C. The purpose of this setting is to remove surface grease. After that, argon protection continuous annealing softening treatment is carried out, the annealing temperature is 800°C, and the online walking speed is 2m / min.

[0080] Continuing from the previous step, the sixth step is leveling: Use a 23-roller leveling machine to level the plate mesh. First, level it 5 times on both sides along the width direction, and then level it 6 times on both sides along the length direction. The leveling pressure for each pass is 3 tons.

[0081] Continuing from the previous step, the seventh step, sizing: After leveling, use the shearing machine to perform bilateral precision sizing according to the preset size to prepare a 1.5*650*L finished mesh plate, see Figure 4 shown.

[0082] Comparative Example 1

[0083] The titanium strip coil with a unit weight of 2.0 tons was stretched. The grade was TA2, annealed state, tensile strength was 405Mpa, specification size was 1.0*710*L, and the inner diameter of the titanium coil was 610mm. After the titanium coil was automatically unrolled and threaded, it was punched, stretched, and sheared on the metal stretching machine without lubrication pretreatment. The mesh size was 4*8mm, the stretching speed was 12 mm / s, and the tensile deformation rate was 50%. After the stretching, curling and cracking occurred locally. Figure 5 shown.

[0084] Comparative Example 2

[0085] A titanium strip coil with a unit weight of 2.3 tons was stretched. The grade was GR2, annealed state, tensile strength was 385Mpa, specification size was 1.5*680*L, and the inner diameter of the titanium coil was 508mm. After the titanium coil was automatically unrolled and threaded, it was punched, stretched, and sheared on a metal stretching machine without lubrication pretreatment. The mesh size was 6*12.5mm, the stretching speed was 5.5mm / s, the tensile deformation rate was 57%, and then 3 passes of flattening were performed, with a pressure of 550 tons per pass and a total deformation rate of about 51%. After flattening, the titanium mesh curled directly, making it impossible to carry out the next process production normally. Figure 6 shown.

[0086] Comparative Example 3

[0087] The titanium strip coil with a unit weight of 3.2 tons was stretched, with the grade TA1, annealed state, tensile strength of 360Mpa, specification size 1.2*1030*L, and the inner diameter of the titanium coil was 508mm. The mesh size was 3*6mm, the mesh speed was 5 mm / s, the tensile deformation rate was 38%, and then 12 passes of flattening were performed, with a pressure of 200 tons per pass, and the total deformation rate was about 33%. After flattening, no softening treatment was performed, and the 23-roller leveling machine was directly used to level the plate mesh in 8 passes along the length direction on both sides, with a leveling pressure of 2.3 tons per pass, to obtain the mesh plate. Figure 7 shown.

[0088] pass Figure 1 to Figure 7 By comparison, it can be seen that the titanium mesh obtained by the preparation method of the present invention has a smooth surface, no defects, and high flatness.

[0089] The unevenness of the titanium mesh plates after leveling in Examples 1 to 4 and Comparative Example 3 was tested, and the test results are shown in Table 1 below.

[0090] Table 1

[0091]

[0092] It can be seen from the data in Table 1 above that the unevenness of the titanium mesh plate after leveling in Comparative Example 3 is extremely poor, reaching 85 mm / m; the high-strength ultra-wide titanium mesh plates prepared in Examples 1 to 3 of the present invention meet the requirements of a thickness of 0.5 to 1.5 mm and a width of 650 to 1500 mm, and the strength of the selected titanium alloy plate reaches more than 300 MPa, and the flatness of the titanium mesh plate is between 5 and 10 mm / m.

[0093] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A method for preparing a high-strength ultra-wide titanium mesh plate, characterized in that: The steps include: S1: Raw material preparation; select titanium coils with tensile strength ≤420Mpa, thickness 0.5~1.5mm, width 680~1530mm, unit weight ≤5 tons, and inner diameter 508mm or 608mm; S2: pre-processing; S3: Punching and mesh drawing: Punching, mesh drawing and shearing are performed on the metal mesh drawing machine; S4: Flattening: Place the titanium mesh on a flattening machine for multiple passes of flattening; S5: softening treatment; S6: Leveling: Use a 23-roller leveling machine to level the titanium mesh, first leveling the front and back sides along the width direction, and then leveling the front and back sides along the length direction.

2. The preparation method according to claim 1, characterized in that: In step S1 , the titanium coil is in an annealed state.

3. The preparation method according to claim 1, characterized in that: In step S2, the pretreatment process is to apply lubricant on the upper and lower surfaces of the titanium coil after automatic unwinding and tape threading.

4. The preparation method according to claim 1, characterized in that: In step S3, the net drawing speed is 6 to 10 mm / s, and the tensile deformation rate is 40 to 60%.

5. The preparation method according to claim 1, characterized in that: In step S3, the short pitch size of the mesh of the stretched net is 3-6 mm, and the long pitch size is 6-12.5 mm.

6. The preparation method according to claim 1, characterized in that: In step S4, 3 to 10 passes of flattening are performed in the length direction, the pressure of each pass is 300 to 400 tons, the deformation of a single pass is controlled within 10%, and the total deformation rate is 35 to 55%.

7. The preparation method according to claim 1, characterized in that: In step S5, the softening process further includes the following steps: S51, pickling; S52, drying; S53: Annealing treatment.

8. The preparation method according to claim 7, characterized in that: The specific process of the annealing treatment in step S53 is that the annealing temperature is 750-800° C. and the online walking speed is 2-10 m / min.

9. The preparation method according to claim 1, characterized in that: The specific parameters of leveling in step S6 are: in the width direction, leveling is performed on both sides in 2 to 5 passes; in the length direction, leveling is performed on both sides in 3 to 6 passes, and the leveling pressure for each pass is 3 to 5 tons.

10. The preparation method according to claim 1, characterized in that: In step S6, the unevenness after leveling is ≤10 mm / m.

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