Method for carrying out plate shape stretch bending and straightening on stainless steel foil by using multi-roller straightening machine

Abstract

The invention provides a method for carrying out plate shape stretch bending straightening on stainless steel foil by using a multi-roller straightening machine, which can be used for carrying out stretch bending straightening on the stainless steel foil with the thickness of 0.02-0.06 mm and the width of more than or equal to 600mm, and comprises the following steps: a plate shape adjusting stage, the plate shape precision and the size shape of the stainless steel foil are adjusted through the micro-tension and the micro-rolling reduction, and the adjusted stainless steel foil is obtained; in the plate shape straightening stage, the straightened stainless steel foil is obtained by adjusting wave shapes or refining of the straightened plate shape of the stainless steel foil through large tension and large rolling reduction; and in the finished product control stage, the final flatness and surface quality of the shape of the straightened stainless steel foil are controlled through small tension and small rolling reduction, and the finished stainless steel foil is obtained. By means of the multi-section dynamic control and real-time wave shape repairing technology, the straightening precision and production efficiency of the ultrathin stainless steel foil are greatly improved, meanwhile, wave shape defects and material losses are reduced, and the intelligent and automatic level is high.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal foil manufacturing, and relates to a method for straightening the shape of stainless steel foil by using a multi-roll straightening machine. Background Art

[0002] With the rapid development and popularization of fields such as battery current collectors, mobile phone cooling plates, and flexible displays in China, there is an urgent need for domestic high-quality precision ultra-thin wide-width stainless steel foil products. Especially for ultra-thin wide-width stainless steel foils with a thickness of 0.02 - 0.06 mm and a width exceeding 600 mm, such as ultra-thin stainless steel foils for flexible printed circuits (FPCs) and precision electronic components in the field of electronic manufacturing, the thickness is generally required to be in the range of 0.02 - 0.05 mm, and the IU value (flatness index) is generally required to be ≤ 5 - 10 IU to ensure that the components will not have assembly errors or functional failures due to the uneven surface of the material during the manufacturing process with extremely high precision. In the new energy field, for ultra-thin stainless steel foils used in solar cells and fuel cells, higher requirements are placed on the flatness of the shape. Especially in battery current collectors, the flatness is usually required to be ≤ 0.1 mm / m. The requirement for flatness in the new energy field is slightly lower than that in the electronic and aerospace fields, generally required to be ≤ 10 - 15 IU, to ensure that the material will not produce wrinkles or deformations during the processing, affecting its performance.

[0003] Due to the complexity and difficulty of the manufacturing process caused by its material properties and the compatibility problem of the width-thickness ratio, extremely strict requirements are placed on its flatness and surface quality. However, traditional straightening processes often cannot completely eliminate wavy defects, such as middle waves, double-sided waves and other wavy defects, which affect the final appearance quality and mechanical properties of the material. At the same time, the existing processes lack an automated real-time detection and repair system and are difficult to adjust dynamically during the production process, resulting in a high rejection rate.

[0004] Therefore, an innovative straightening process that can monitor and adjust the tension and reduction in real time is needed to meet the dimensional accuracy requirements of ultra-thin wide-width stainless steel foils in high-end application fields. Summary of the Invention

[0005] To solve the defects existing in the existing processes, the present invention provides a system for three-stage dynamic tension control and real-time detection and repair of waviness, which is specifically used for straightening ultra-thin wide-width stainless steel foils with a thickness of 0.02 - 0.06 mm and a width of more than 600 mm. This process can dynamically adjust process parameters such as tension and elongation during production, detect and repair waviness defects in real time, ensure that the finished product has extremely high flatness and perpendicularity, and meet the requirements of high-end applications. Moreover, the present invention adopts a technical process path of multi-stage dynamic tension control and real-time detection and repair of waviness to achieve high-precision shape control, which is particularly suitable for the shape straightening of stainless steel foils with a thickness of 0.02 - 0.06 mm and a width exceeding 600 mm, and can be widely applied in fields such as aerospace, new energy, and electronic manufacturing.

[0006] The present invention can use a roller straightening machine and a stretch straightening machine, that is, a combination of S rollers and 23-roller boxes. The roller straightening machine straightens the stainless steel foil by repeatedly bending it multiple times through multiple rows of mutually staggered straightening rollers. When the stainless steel foil passes through the straightening rollers, it is subjected to the pressure of the rollers and undergoes bending deformation. After multiple repeated bends, the curvature gradually decreases until it becomes flat. The stretch straightening machine applies a tensile force exceeding the material yield limit to the stainless steel foil through jaws, causing it to undergo plastic elongation, thereby straightening the material. In terms of structural characteristics, the straightening machine generally has two or more rows of straightening rollers, with varying numbers. The position of the rollers forms a certain angle with the movement direction of the material to be straightened and rotates in the same direction driven by a motor. In order to achieve the required compression of the rollers on the product, some small rollers can be adjusted forward or backward simultaneously or separately. In addition, the straightening machine is also equipped with components such as a hydraulic station, a reduction gearbox, and a transmission box, as well as lubrication, cooling, and control systems to ensure the stability and efficiency of the straightening process.

[0007] It should be noted that before stretch-bending straightening, a multi-roll stretch straightening machine is used to perform stretch-bending straightening on the ultra-thin wide-width stainless steel foil; the initial plate shape is double-sided waves on the OS operator side and the DS drive side, and the initial process parameters are set as the uncoiling tension is set to 1 kN, the rewinding tension is set to 1 kN, and the front and rear roll gaps are 0.05 mm; the force feedback changes of the stainless steel foil are captured by sensors, and the initial waviness amplitude and the distribution position of the double-sided waves of the original plate shape are recorded. Then the feedback data is transmitted to the control system to adjust the first support roller and the seventh support roller on the OS operator side and the DS drive side in the roll box to approximately 1.5, and through an independent adjustment unit, the working roll with a given pressure is uniformly deflected to reduce the accumulated strain and ensure the consistency of the transverse plate shape of the ultra-thin wide-width stainless steel foil.

[0008] To achieve the above object, the present invention provides a method for shape stretch-bending straightening of stainless steel foil using a multi-roll straightening machine, wherein this method can perform stretch-bending straightening on stainless steel foils with a thickness of 0.02 - 0.06 mm and a width ≥ 600 mm, and this method includes:

[0009] Shape adjustment stage: Adjust the shape accuracy and dimensional shape of the stainless steel foil through micro-tension and micro-reduction to obtain the adjusted stainless steel foil, where the micro-tension ≤ 50 N / mm 2 , the micro-reduction is -1.0 mm to -1.5 mm, the elongation is 0.08 to 0.1%, and the speed is 20 to 50 m / min.

[0010] Shape straightening stage: Straighten the waviness or refine the shape of the adjusted stainless steel foil through large tension and large reduction to obtain the straightened stainless steel foil, where the large tension is 100 to 700 N / mm 2 , the large reduction is -1.0 mm to -2.5 mm, the elongation is 0.2 to 0.6%, and the speed is 90 to 180 m / min.

[0011] During the rolling and cooling processes, due to uneven deformation and uneven cooling, the stainless steel foil generally exhibits shape defects such as sickle bend, transverse camber, edge waves (single-sided or double-sided), center waves, longitudinal warping, and twisting, that is, the rolled piece has a certain original shape curvature in the initial state. The straightening principle of the straightening machine is to make the rolled piece undergo multiple reverse bends by the straightening rolls arranged in a staggered manner in the straightening machine, causing a certain yield deformation in the outer layer metal of the transverse section of the stainless steel foil, elongating the shorter or tighter parts, and gradually reducing the unevenness of the original curvature, thereby obtaining the required flatness and smaller residual stress.

[0012] To discuss the situation of the stainless steel foil in the state of no initial stress before straightening, for the case of uneven distribution of residual stress in the longitudinal direction of the stainless steel foil to be straightened, an initial stress load is applied in the model for simulation tests. The method of simulating residual stress is to make the stainless steel foil generate unevenly distributed residual stress longitudinally by applying an initial stress load before straightening the stainless steel foil. After applying the initial stress load, the internal stress distribution before straightening, that is, the initial stress load is unevenly distributed along the longitudinal direction of the stainless steel foil. There is a large compressive stress at the front end of the plate, while the middle part is in tensile stress, that is, there is an uneven distribution of internal stress in the longitudinal direction of the entire stainless steel foil, and there are waves in the longitudinal shape of the plate visually.

[0013] Final product control stage: Control the final flatness and surface quality of the shape of the straightened stainless steel foil through small tension and small reduction to obtain the finished stainless steel foil, where the small tension ≤ 80 N / mm 2 , the small reduction is -1.5 mm to -2.0 mm, the elongation is 0.1 to 0.2%, and the speed is 30 to 80 m / min.

[0014] For two sets of bending values, unit nodes on the same cross-section in the middle of the stainless steel foil are selected for comparison. Although the residual stress distribution after straightening simulation is relatively uniform for the bending method using the large deformation linear decreasing principle, the value is much larger than the other two. For the bending method using the small deformation principle, although the numerical results do not differ much, the distribution is not very uniform. Due to the different roll gap values, the straightening forces of each roll after simulation will naturally be different. The results of both sets of simulation experiments show that the smaller the roll gap value, the greater the straightening force of the roll.

[0015] According to an embodiment of the present invention, the uncoiling tension of the multi-roll straightening machine is 1 - 3 kN, the rewinding tension is 1 - 2.5 kN, and the tension of tension leveling is 50 - 700 N / mm 2 , the total elongation is 0.08 - 0.7%, and the difference in roll gap between the front and rear rolls is 0.05 - 0.1 mm.

[0016] According to an embodiment of the present invention, the hardness of the stainless steel foil is 130 - 410 HV.

[0017] According to an embodiment of the present invention, the final flatness of the finished stainless steel foil is ≤ 0.05 mm / m, and the perpendicularity is ≤ 10 mm / m.

[0018] According to an embodiment of the present invention, the multi-roll straightening machine is a 23-roll precision tension leveling machine, and the roll system configuration inside the roll box is 23 rolls.

[0019] According to an embodiment of the present invention, the multi-roll straightening machine is equipped with a waviness real-time detection and automatic pressure adjustment device for real-time repair and adjustment of waviness defects such as edge waves and middle waves.

[0020] According to an embodiment of the present invention, the multi-roll tension leveling machine is equipped with an intelligent dynamic control system that collects and analyzes the thickness, width, tension, and waviness data of the stainless steel foil in real time.

[0021] It should be noted that in order to check the accuracy of the straightening roll adjustment, a longitudinal band is marked on the surface of the working rolls with chalk, and then a roll of stainless steel foil is passed through the straightening machine. The contact length between the straightening roll and the stainless steel foil is determined according to the degree to which the chalk mark is erased. Visually check whether there are obvious spiral marks on the surface of the stainless steel foil. If the contact length between the straightening roll and the stainless steel foil is insufficient, one of the following methods or a combination of the three methods can be used to achieve the required value. This method is to increase the reduction amount, that is, each straightening roll moves radially closer; the second method is to reduce the arrangement angle of the upper roll; the third method is to reduce the arrangement angle of the side roll. When obvious spiral marks are found on the straightened stainless steel foil, they are eliminated by reducing the reduction amount and increasing the arrangement angles of the upper roll and the side roll.

[0022] After adjustment, the straightening machine can achieve a straightening accuracy of not less than 0.2 mm / m. After reinspection 24 hours later, it was confirmed that the high flatness of the straightened pipe did not deteriorate. Practice has proved that the high-precision stability of stainless steel foil straightening decreases with the decrease of the yield limit of stainless steel foil. This is because there is a certain reduction in the closed pass of the straightening machine for that section of stainless steel foil, which makes the axial bending of the stainless steel foil straighten and the cross-section compress.

[0023] The beneficial effects of this invention patent are as follows:

[0024] First, through multi-segment dynamic control and real-time waviness repair technology, the invention greatly improves the straightening accuracy and production efficiency of ultra-thin stainless steel foil, reduces waviness defects and material losses at the same time, and has a high level of intelligence and automation. For the production of ultra-thin wide-width stainless steel foil with high precision and not easy to deform, it can meet the strict requirements of various high-end applications for material quality, flatness and surface finish, reduce production costs and optimize energy consumption at the same time. These advantages make the invention applicable to multiple high-precision manufacturing fields, especially industries such as electronics, aerospace, and medical that have extremely high requirements for flatness.

[0025] Second, by controlling the force on the cross-section of the foil during the tension straightening process, the invention monitors and feedbacks the force condition and waviness defects of the foil in real time, makes real-time adjustment feedback and real-time control by automatically adjusting the bearing pressure of the support rolls, ensuring the flatness of the material throughout the production process.

[0026] Third, by using an intelligent dynamic control system, the invention automatically optimizes process parameters according to historical data and real-time sensor feedback, ensuring that stainless steel foils with different thicknesses and widths are always in the best processing state.

[0027] Fourth, the invention adopts a technical process path of multi-segment dynamic tension control and real-time waviness detection and repair system to achieve high-precision shape control, which is especially suitable for shape straightening of stainless steel foils with a thickness of 0.02 - 0.06 mm and a width exceeding 600 mm, and can be widely used in fields such as aerospace, new energy and electronic manufacturing. Description of the Drawings

[0028] Figure 1 It is the process flow chart of the method for shape tension straightening of stainless steel foil using a multi-roll straightening machine in this invention. Specific Embodiments

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings required for the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments described in the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings; the description of at least one exemplary embodiment is actually only illustrative and in no way limits the present invention and its application or use. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0030] It should be noted that the straightening process parameter selection system is the core component of the straightening machine intelligent control system. Its goal is to absorb the process parameter selection experience knowledge from the control process samples of the operators to replace the operators to complete the process parameter selection operation. The modeling of the process parameter selection system is abstracted based on the requirements of the straightening process parameter selection system. It abstractly models the system functions of the straightening process parameter selection system and completes the two basic functions of knowledge acquisition through sample learning and process parameter selection.

[0031] The research on the on-site working process of the straightening machine and the process parameter selection system puts forward the following functional requirements for the process parameter selection system:

[0032] 1) It is required to establish a sample library inside the process parameter selection system to store all the collected samples for query and research.

[0033] 2) It is required to establish a knowledge base inside the process parameter selection system, put the process parameter selection experience knowledge obtained through sample learning into the knowledge base according to a certain data structure, and classify the knowledge according to attribute information such as sheet thickness, and different types of knowledge should be stored separately.

[0034] 3) The process parameter selection system must be able to work continuously to adapt to the continuous working mode of the straightening machine without stopping. At the same time, knowledge acquisition and process parameter selection need to be alternated to continuously and dynamically update the knowledge base.

[0035] Embodiment 1

[0036] The thickness of the stainless steel foil to be stretch-bent and straightened is 0.03 mm, the width is 650 mm, and the detected hardness range is 150 HV. The configurations at each stage are as follows.

[0037]

[0038]

[0039] The final flatness of the obtained finished stainless steel foil is 0.03 mm / m, and the perpendicularity is 8.5 mm / m.

[0040] Example 2

[0041] The thickness of the stainless steel foil to be stretch-bend straightened is 0.04 mm, the width is 700 mm, and the detected hardness range is 200 HV. The configurations at each stage are as follows.

[0042]

[0043] The final flatness of the obtained finished stainless steel foil is 0.046 mm / m, and the perpendicularity is 8.4 mm / m.

[0044] Example 3

[0045] The thickness of the stainless steel foil to be stretch-bend straightened is 0.046 mm, the width is 750 mm, and the detected hardness range is 400 HV. The configurations at each stage are as follows.

[0046]

[0047]

[0048] The final flatness of the obtained finished stainless steel foil is 0.048 mm / m, and the perpendicularity is 9.3 mm / m.

[0049] To illustrate the advantages of the present invention over the prior art, the inventor designed three comparative examples to compare the performance of the obtained stainless steel foils.

[0050] Comparison 1

[0051] The parameters are the same as those in Example 1, and the difference is that the plate shape adjustment stage is not carried out. The final flatness of the obtained finished stainless steel foil is 0.13 mm / m, and the perpendicularity is 9.8 mm / m.

[0052] Comparison 2

[0053] The parameters are the same as those in Example 2, and the difference is that the plate shape straightening stage is not carried out. The final flatness of the obtained finished stainless steel foil is 0.24 mm / m, and the perpendicularity is 9.4 mm / m.

[0054] Comparison 3

[0055] The parameters are the same as those in Example 3, and the difference is that the finished product control stage is not carried out. The final flatness of the obtained finished stainless steel foil is 0.31 mm / m, and the perpendicularity is 9.2 mm / m.

[0056] From the above comparison, it can be seen that the method of the present invention ensures better flatness and shape and size accuracy of the stainless steel foil by precisely controlling the tension, reduction and elongation.

[0057] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit them; although the present invention has been described in detail with reference to the embodiments, those of ordinary skill in the art should understand that any modification or equivalent replacement of the technical solutions of the present invention does not depart from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A method for straightening stainless steel foil using a multi-roll straightening machine, wherein the method can straighten the stainless steel foil with a thickness of 0.02 to 0.06 mm and a width of ≥ 600 mm, and the method comprises: Plate shape adjustment stage: The plate shape accuracy and size of the stainless steel foil are adjusted by micro tension and micro pressure to obtain the adjusted stainless steel foil, wherein the micro tension is ≤50N / mm 2 , the micro-pressure reduction is -1.0mm to -1.5mm, the elongation is 0.08 to 0.1%, and the speed is 20 to 50m / min; Plate straightening stage: The stainless steel foil is straightened by high tension and high pressure to obtain a straightened stainless steel foil. The high tension is 100-700 N / mm. 2 , the maximum reduction is -1.0 mm to -2.5 mm, the elongation is 0.2 to 0.6%, and the speed is 90 to 180 m / min; and Finished product control stage: The final flatness and surface quality of the straightened stainless steel foil are controlled by small tension and small pressure reduction to obtain the finished stainless steel foil, wherein the small tension is ≤80N / mm 2 The small reduction is -1.5mm to -2.0mm, the elongation is 0.1 to 0.2%, and the speed is 30 to 80m / min.

2. The method for straightening stainless steel foil according to claim 1, wherein the unwinding tension of the multi-roll straightening machine is 1-3 kN, the winding tension is 1-2.5 kN, and the straightening tension is 50-700 N / mm 2 The total elongation is 0.08-0.7%, and the gap difference between the front and rear rollers is 0.05-0.1mm.

3. The method for straightening a stainless steel foil according to claim 1, wherein the hardness of the stainless steel foil is 130-410 HV.

4. The method for straightening stainless steel foil by stretching, bending and straightening according to claim 1, wherein the final flatness of the finished stainless steel foil obtained is ≤0.05 mm / m, and the verticality is ≤10 mm / m.

5. The method for straightening stainless steel foil by stretching, bending and straightening according to claim 1, wherein the multi-roller straightening machine is a 23-roller precision straightening machine, and a 23-roller roller system is configured in the roller box.

6. The method for straightening stainless steel foil by stretching, bending and straightening according to claim 1, wherein the multi-roller straightening machine is equipped with a real-time wave shape detection and automatic pressure adjustment device for real-time repair and adjustment of wave shape defects such as edge waves and middle waves.

7. The method for straightening stainless steel foil according to claim 1, wherein the multi-roll straightening machine is equipped with an intelligent dynamic control system for real-time collection and analysis of the thickness, width, tension and wave shape data of the stainless steel foil.

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