Cold rolling method for ultra-thin silicon steel

Abstract

The invention belongs to the field of plate and strip rolling and relates to an ultra-thin silicon steel cold rolling method. The ultra-thin silicon steel cold rolling method is divided into a material preparation stage and a cold rolling stage. The material preparation stage comprises the steps of obtaining raw materials, and treating the raw materials according to the steps of smelting, casting, hot rolling, normalizing and pickling to obtain a first strip, that is, quantitative analysis is completed on multiple technological parameters of five links of smelting, casting, hot rolling, normalizing and pickling in the material preparation stage, and a basis is provided for guaranteeing the product quality; in the cold rolling stage, the reduction rate, the lubricating parameter, the tensile stress and the same plate difference are adjusted so that the first strip can be thinned, the same plate difference of the thinned first strip is controlled within the range of + / -3 m, and a target strip is obtained, that is, in the cold rolling stage, a lubricating scheme with the large reduction rate, the high oil temperature and the low oil quantity and a large-tension rolling technology are adopted; and the minimum rolling thickness limit is broken through, and the high same plate difference requirement is met.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of strip rolling, and particularly relates to a cold rolling method for extremely thin silicon steel. BACKGROUND

[0002] The extremely thin silicon steel is an important soft magnetic alloy indispensable for the electric power, electronic and military industries, and is also the largest metal functional material, which is mainly used for manufacturing various electric machines, transformers, mutual inductors, relays and household appliances. At present, China cannot realize self-production of the steel, and in the actual production-research process, the following obvious disadvantages exist: (1) The process research and development lacks integrity. At present, the research on the rolling of the extremely thin silicon steel by colleges and universities, research institutes and production enterprises is mainly anchored to a certain technical link, so that the process research and development is not smooth due to the lack of integrity, and when the product has a problem, the specific process corresponding to the cause cannot be investigated, which greatly limits the development of the silicon steel technology and causes the ferromagnetic properties of the final product to be unable to meet the terminal requirements.

[0003] (2) The equipment research and development lacks systematization. At present, the silicon steel is mainly produced by six-roller rolling mills or Sendzimir mills. The six-roller rolling mill can only produce slightly thick silicon steel, and the product thickness is relatively large, which causes the iron loss to be high and affects the ferromagnetic properties; the Sendzimir mill can produce relatively thin strips, but due to the limited opening degree of the equipment and the hard and brittle characteristics of the product, once the strip breaks during the rolling process, the cleaning of the broken strip residue is extremely difficult. SUMMARY

[0004] The application aims to provide a cold rolling method for extremely thin silicon steel to overcome the above technical defects.

[0005] To solve the above technical problems, the application provides a cold rolling method for extremely thin silicon steel, which comprises the following steps: Step 100, a material preparation stage; Obtaining raw materials, processing the raw materials according to the steps of smelting, casting, hot rolling, normalizing and pickling to obtain a first strip; Step 200, a cold rolling stage; In the cold rolling stage, the reduction rate, lubrication parameters, tensile stress and plate difference are adjusted to thin the first strip, and the plate difference of the thinned first strip is controlled within the range of ±3 µm to obtain a target strip.

[0006] According to the cold rolling method for extremely thin silicon steel, the smelting step comprises: in the smelting link, the mass fraction of silicon in the raw material is controlled to be 3.4%-3.6% to reduce the iron loss and maintain the ferromagnetic properties, so as to obtain a casting blank.

[0007] According to the ultra-thin silicon steel cold rolling method, the casting step includes: using a continuous casting process to slowly cool and heat-hold the billet to prevent the generation of hidden cracks and coarse grains.

[0008] According to the cold rolling method for ultra-thin silicon steel, the hot rolling step includes: Adjust the heating temperature to 1250-1350 degrees Celsius to control the degree of solid solution of the inhibitor in the billet; Adjust the final rolling temperature to 850-950 degrees Celsius to control the precipitation of inhibitors in the billet; Adjust the winding temperature to 550-650 degrees Celsius to control the formation of iron oxide scale.

[0009] According to the cold rolling method for ultra-thin silicon steel, the normalizing step includes: controlling the normalizing temperature to 1000-1100 degrees Celsius, holding the temperature for 2-3 minutes, and spraying water for rapid cooling to improve magnetism and reduce iron loss, thereby obtaining hot-rolled strip.

[0010] According to the cold rolling method for ultra-thin silicon steel, the pickling step includes a shot peening pretreatment step and a formal pickling step. In the shot peening pretreatment stage, the shot peening flow rate is 800-1000 kg / min, and the shot peening particles are 1.0 mm steel particles. The shot peening is used to remove the iron oxide scale on the surface of the hot-rolled strip. In the formal pickling process, hydrochloric acid is selected as the acid solution, with a mass fraction of 3% and a pickling temperature of 75 degrees Celsius, to obtain the first strip.

[0011] According to the ultra-thin silicon steel cold rolling method, in the cold rolling stage, the reduction rate, lubrication parameters, tensile stress, and sheet thickness are adjusted to thin the first strip, and the sheet thickness of the thinned first strip is controlled within ±3µm to obtain the target strip, including the following steps: Maintain a reduction rate of over 85% to generate a large amount of deformation heat; The temperature of the lubricating medium is controlled at 55 degrees Celsius and the lubricating oil volume is 12000 ml / min. The high oil temperature and low oil volume lubrication scheme minimizes the heat carried away by the lubricating medium from the first strip. Adjust the tensile stress of the first strip to 40% of the yield strength of the current pass; The first strip is introduced into the ultra-thin silicon steel cold rolling production system. The ultra-thin silicon steel cold rolling production system is used to eliminate the wedge shape and control the same plate difference of the thinned first strip within the range of ±3µm to obtain the target strip.

[0012] According to the ultra-thin silicon steel cold rolling method, the ultra-thin silicon steel cold rolling production system includes: Archway; The tower-shaped roller system consists of an upper roller system and a lower roller system, both of which are installed inside the archway. A servo cylinder is located below the lower roller system. The servo cylinder controls the overall lifting and lowering of the lower roller system to change the mill opening. The mill opening is suitable for the strip rolling of ultra-thin silicon steel, strip breakage treatment, and residue cleaning.

[0013] According to the cold rolling method for ultra-thin silicon steel, both the upper roll system and the lower roll system consist of ten rolls. The ten rolls are arranged in a tower shape, with the innermost ring being the work rolls and the outermost ring being the support rolls; There are four support rollers; The four support rollers are arranged in a fan shape, with the center of the fan pointing towards the working roller; Each of the support rollers includes at least a mandrel on which a plurality of thick-walled bearings are fitted. The four support rollers arranged in a fan shape consist of two intermediate support rollers and two side support rollers. The two intermediate support rollers have the same number of thick-walled bearings, and the two side support rollers have the same number of thick-walled bearings. However, the number of thick-walled bearings on the side support rollers differs from the number of thick-walled bearings on the intermediate support rollers by one.

[0014] According to the ultra-thin silicon steel cold rolling method, the upper roller system can be raised and lowered as a whole; During rolling production, the upper roller system is in a locked state; During non-rolling production, the lifting height of the upper roller system is adjusted to keep the rolling line in a preset position. Non-rolling production includes roller replacement, rolling line calibration, or re-grinding of the rollers. The archway includes at least an operating side frame and a transmission side frame; The extension and retraction of the servo cylinder can make the lower roller system tilted along the operating side or the transmission side to eliminate the wedge shape and control the same plate difference of the first strip within ±3µm. The operating side is the side where the operating side frame is located, and the transmission side is the side where the transmission side frame is located.

[0015] The beneficial effects of this invention are as follows: (1) This invention has developed a complete process flow that affects the quality of silicon steel, and proposed a cold rolling method for ultra-thin silicon steel, which is divided into a material preparation stage and a cold rolling stage. Quantitative analysis was completed on many process parameters of the five links in the material preparation stage, namely smelting, casting, hot rolling, normalizing and pickling, which provides a foundation for ensuring product quality. In the cold rolling stage, a lubrication scheme with high reduction rate, high oil temperature and low oil volume and high tension rolling process were adopted to break through the minimum rollable thickness limit and achieve high plate difference requirements.

[0016] (2) Based on the process characteristics of the cold rolling stage, an ultra-thin silicon steel cold rolling production system with both large opening and high roll system rigidity was developed. The arrangement of the tower-shaped roll system not only meets the small roll diameter required for rolling ultra-thin silicon steel strip, but also ensures the overall rigidity of the roll system; the overall lifting and lowering of the roll system driven by the servo cylinder meets the requirements for large opening in situations such as strip threading and maintenance, and the large internal space arrangement provides convenience for handling accidents such as strip breakage.

[0017] To make the above description of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0018] Figure 1 This is a flowchart of the cold rolling process for ultra-thin silicon steel.

[0019] Figure 2 This is a cross-sectional view of an ultra-thin silicon steel cold rolling production system.

[0020] Figure 3 This is a structural diagram of an ultra-thin silicon steel cold rolling production system.

[0021] Figure 4 This is a diagram showing the arrangement of the upper and lower roller systems.

[0022] Figure 5 This is a diagram showing the distribution of thick-walled bearings for the support rollers.

[0023] Explanation of reference numerals in the attached figures: A. Archway; B. Upper roller system; C. Lower roller system; D. Servo cylinder; 1. Operating side frame; 2. Transmission side frame; 3. Upper crossbeam; 4. Lower crossbeam. Detailed Implementation

[0024] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0025] It should be noted that, in this invention, the upper, lower, left, and right in the figure are regarded as the upper, lower, left, and right of the ultra-thin silicon steel cold rolling method described in this specification.

[0026] Exemplary embodiments of the present invention will now be described with reference to the accompanying drawings. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein. These embodiments are provided to fully and completely disclose the invention and to fully convey its scope to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the drawings is not intended to limit the invention. In the drawings, the same units / elements are referred to by the same reference numerals.

[0027] Unless otherwise stated, the terms used herein (including technical terms) have their common meaning as understood by one of ordinary skill in the art. Furthermore, it is understood that terms defined in commonly used dictionaries should be understood to have a meaning consistent with the context of their relevant field, and not to be interpreted as having an idealized or overly formal meaning.

[0028] This embodiment relates to a cold rolling method for ultra-thin silicon steel. Please refer to [link / reference]. Figure 1 The process includes the material preparation stage and the cold rolling stage, which will be described in detail below.

[0029] Step 100, Material Preparation Stage.

[0030] Only by strictly controlling the influencing factors such as the elemental composition, microstructure, and geometric dimensions of the raw materials within a certain range during the material preparation stage can the ferromagnetic properties of the product be guaranteed to the maximum extent and edge cracks be avoided, or can the thickness difference accuracy and plate difference accuracy be guaranteed during the cold rolling stage.

[0031] According to the sequence of production processes, the material preparation stage includes at least obtaining raw materials, processing the raw materials according to the steps of smelting, casting, hot rolling, normalizing, and pickling, and obtaining the first strip.

[0032] The smelting process includes: controlling the silicon content of the raw materials to 3.4%-3.6% in order to reduce iron loss and maintain ferromagnetic properties, thereby producing a cast billet.

[0033] Specifically, maintaining the silicon content at around 3.5% during the smelting process reduces iron loss while maintaining high mechanical properties. This is because, within a certain range, increasing the silicon content can reduce eddy current losses and coercivity, but when the silicon content exceeds 3.5%, the yield strength and elongation decrease, and coarse grains are also produced. Conversely, if the silicon content is too low, the increased iron loss will severely affect the magnetic flux density. Therefore, the silicon content is crucial to the final product's mechanical properties and ferromagnetic characteristics.

[0034] The casting process includes: using continuous casting technology to slowly cool and hold the billet to prevent the formation of hidden cracks and coarse grains.

[0035] Slow cooling refers to placing high-temperature steel in a slowly cooling environment to achieve the desired microstructure and mechanical properties. Heat preservation refers to the key technology of controlling the temperature changes of steel during rolling to ensure it remains within a suitable temperature range during processing, thereby guaranteeing product quality, performance, and production efficiency.

[0036] The casting process employs continuous casting technology, and the use of slow cooling and heat preservation techniques on the billet prevents the formation of cracks and coarse grains. Ingot casting (i.e., the billet obtained in the smelting process) has numerous surface defects and a low yield, hence the use of continuous casting. Through the synergistic effect of casting speed and molten steel, slow cooling and heat preservation techniques effectively control the grain size of the billet and prevent the propagation of latent cracks, while also reducing steel oxidation. This lays the foundation for subsequent processes to avoid porosity and edge cracks.

[0037] The hot rolling process includes: adjusting the heating temperature to 1250-1350 degrees Celsius to control the solid solution degree of the inhibitor in the billet; adjusting the final rolling temperature to 850-950 degrees Celsius to control the precipitation of the inhibitor in the billet; and adjusting the coiling temperature to 550-650 degrees Celsius to control the formation of iron oxide scale.

[0038] The hot rolling process effectively controls the microstructure and scale by organically coordinating the heating temperature, final rolling temperature, and coiling temperature. The heating temperature is approximately 1250-1350 degrees Celsius, preferably 1300 degrees Celsius. Controlling the heating temperature allows for control over the degree of solid solution of inhibitors in the billet. The final rolling temperature is approximately 850-950 degrees Celsius, preferably 900 degrees Celsius. Controlling the final rolling temperature effectively controls the precipitation of inhibitors. The coiling temperature is approximately 550-650 degrees Celsius, preferably 600 degrees Celsius. Controlling the coiling temperature reduces the formation of scale and reduces pickling difficulties.

[0039] The normalizing step includes: controlling the normalizing temperature at 1000-1100 degrees Celsius, holding the temperature for 2-3 minutes, and spraying water for rapid cooling to improve magnetism and reduce iron loss, thereby obtaining hot-rolled strip.

[0040] The normalizing process achieves high-precision control over secondary recrystallization and inhibitor precipitation through overall control of the normalizing temperature and holding time, thus reducing the occurrence of problems such as brittle fracture or cracking during the cold rolling stage. The normalizing temperature is approximately 1000-1100 degrees Celsius, preferably 1050 degrees Celsius, and the holding time is approximately 2-3 minutes, followed by rapid cooling with water spray to improve magnetism and reduce iron loss.

[0041] The pickling process includes shot peening pretreatment and formal pickling. (1) In the shot peening pretreatment stage, the shot peening process is adopted, the shot peening flow rate is 800-1000 kg / min, the shot peening particles are 1.0 mm steel particles, and the iron oxide scale on the surface of the hot rolled strip is removed by shot peening.

[0042] (2) In the formal pickling process, hydrochloric acid is selected as the acid solution, the mass fraction of hydrochloric acid in the acid solution is 3%, the pickling temperature is 75 degrees Celsius, and the first strip is obtained.

[0043] The pickling process consists of two parts: shot peening pretreatment and formal pickling. The shot peening pretreatment uses a shot peening process with a capacity of 800-1000 kg / min and a steel shot particle size of approximately 1.0 mm. A dust extraction device removes the resulting scale, powder, and slag. Shot peening pretreatment breaks down and removes the iron oxide scale on the surface of the hot-rolled strip, reducing the difficulty of acid corrosion in the subsequent formal pickling stage. The formal pickling stage uses hydrochloric acid as the acid solution, with a hydrochloric acid mass fraction of approximately 3%. The pickling temperature is approximately 75 degrees Celsius. The high acid temperature helps to accelerate the pickling process and greatly improves the overall production pace.

[0044] Step 200, cold rolling stage.

[0045] The main process parameters in the cold rolling stage include reduction rate, lubrication parameters, tensile stress, and strip thickness variation. The cold rolling stage not only thins the strip to achieve the desired thickness but also creates favorable conditions for obtaining the ideal primary recrystallization structure and texture. Therefore, the cold rolling stage is a decisive stage affecting product quality. The identification and effective control of key process parameters are crucial to ensuring the overall quality of the product.

[0046] Specifically, during the cold rolling stage, the reduction rate, lubrication parameters, tensile stress, and sheet thickness are adjusted to thin the first strip, and the sheet thickness of the thinned first strip is controlled within ±3µm to obtain the target strip.

[0047] Please continue reading. Figure 1 During the cold rolling stage, the reduction rate, lubrication parameters, tensile stress, and sheet thickness are adjusted to thin the first strip, and the sheet thickness of the thinned first strip is controlled within ±3µm to obtain the target strip. This includes the following steps: Maintain a reduction rate of over 85% to generate a large amount of deformation heat.

[0048] The cold rolling stage employs a high reduction rate process, maintaining the total reduction rate at approximately 85% or higher to achieve good high magnetic induction intensity. The high reduction rate generates a significant amount of deformation heat, and the rapid rolling production rhythm further increases the strip temperature. In other words, rapid rolling prevents heat loss, thus maintaining the strip at a higher temperature to prevent breakage.

[0049] The large amount of deformation heat generated by the high reduction rate can keep the silicon steel strip at a high temperature to resist its inherent hard, brittle and easily broken characteristics and prevent strip breakage.

[0050] The temperature of the lubricating medium is controlled at 55 degrees Celsius, and the lubricating oil volume is 12000 ml / min. The high oil temperature and low oil volume lubrication scheme minimizes the heat carried away by the lubricating medium from the first strip.

[0051] A lubricating oil temperature of 55 degrees Celsius and a lubricating oil flow rate of 12000 ml / min can be considered a high-temperature, low-flow-rate lubrication scheme. This scheme minimizes the heat loss from the steel plate (i.e., the first strip) while meeting lubrication requirements. These measures, while increasing the steel plate temperature, not only reduce the risk of edge cracking and brittle fracture in the strip but also enhance the pinning dislocation capacity of the steel strip (i.e., the first strip), hindering dislocation movement and thus altering the cold-rolled texture and further reducing iron loss. This has a positive effect on improving the toughness of the steel strip (i.e., the first strip), reducing strip breakage during rolling, and increasing the yield.

[0052] Adjust the tensile stress of the first strip to 40% of the yield limit of the current pass.

[0053] The cold rolling stage employs a high-tension rolling process, with the strip tensile stress approximately 40% of the yield limit of the current pass. This high tensile stress helps to overcome the bottleneck of minimum rollable thickness. When the product thickness is relatively thin, simply increasing the rolling pressure only causes elastic deformation of the rolls and die, without further reducing the strip's exit thickness. Especially when the roll ends come into contact, the increased rolling force can even cause irreversible damage to the electromechanical and hydraulic equipment (i.e., mechanical, electrical, and hydraulic equipment). At this point, only by increasing the tensile stress borne by the strip can this thickness limit be overcome. Furthermore, further reducing the strip thickness can significantly reduce iron loss and improve the product's magnetic properties.

[0054] The first strip is introduced into the ultra-thin silicon steel cold rolling production system. The ultra-thin silicon steel cold rolling production system is used to eliminate the wedge shape and control the thickness difference of the first strip within ±3µm to obtain the target strip.

[0055] The cold rolling stage employs roll tilting technology, which can effectively compensate for and suppress wedge-shaped strips. Furthermore, through the integrated use of the strip shape system and thickness control system, the strip's same-strip difference can be controlled within ±3µm. A high same-strip difference helps to improve the stacking coefficient and increase its punching performance, which is highly beneficial for reducing iron loss and enhancing magnetic induction intensity.

[0056] Currently, there are three conflicting technical requirements when rolling extremely thin, brittle silicon steel strip: Small roll diameter requirement: In order to reduce rolling deformation resistance and contact arc length and achieve rolling of extremely thin specifications, it is necessary to use work rolls with extremely small diameters (such as 80mm).

[0057] High rigidity requirement: Rolling ultra-thin silicon steel requires huge rolling force, and small-diameter work rolls are prone to bending, vibration and flattening under high pressure. They must be supported by a high-rigidity roll system to ensure the accuracy of plate shape and thickness.

[0058] Large opening required: Due to the hard and brittle nature of silicon steel, it is prone to "strip breakage" during rolling, and the broken strip scatters into fragments. At the same time, threading the strip through small-diameter rolls is difficult. This necessitates a sufficiently large opening in the rolling mill to facilitate the threading operation and thorough cleaning of broken strip residue; otherwise, residual debris can damage expensive components such as bearings.

[0059] The dilemma of existing technology lies in the fact that traditional six-roll mills cannot meet the requirements of small roll diameter and high rigidity; while the Sendkimir-type multi-roll mill (tower roll system), which can meet the requirements of small roll diameter and high rigidity, has a compact structure and an inherently very small opening, which cannot meet the needs of handling broken strips of ultra-thin silicon steel and threading strips in a large space. In other words, under the current technological framework, the three goals of "small roll diameter", "high rigidity" and "large opening" are mutually exclusive and difficult to achieve simultaneously.

[0060] The ultra-thin silicon steel cold rolling production system achieves the three conflicting goals mentioned above simultaneously through the coordinated configuration of a "tower-shaped roller system" and a "servo-cylinder-driven overall lifting and lowering of the lower roller system": The "tower-shaped roll system" primarily resolves the contradiction between "small roll diameter" and "high rigidity". Its multi-layer support structure ensures the vertical and lateral stability of the small-diameter work rolls when subjected to enormous rolling forces, increasing the roll system rigidity to 5 times that of a six-roll mill of the same specifications.

[0061] The "servo-cylinder driven lower roll system overall lifting" mainly solves the contradiction between "high rigidity and compact structure" and "large opening". By lifting the entire lower tower roll system as a rigid unit by a servo-cylinder, a huge opening (up to 90mm) is achieved, which is far greater than that of the traditional Sendkimir mill (for example, up to 12 times its size), without damaging the internal precision structure of the tower roll system.

[0062] Crucially, the combination of these two features produces a synergistic effect: It is precisely because the tower-shaped roll system itself is a highly rigid whole that it can be raised and lowered stably and precisely by the servo cylinder as a single unit. If the roll system is not rigid enough, the overall raising and lowering will cause the roll system to deform, making it impossible to guarantee rolling accuracy.

[0063] Conversely, the precise and stable large-stroke lifting provided by the servo cylinder gives this high-rigidity tower roll system unprecedented process flexibility, enabling it to handle both high-precision ultra-thin rolling and quick conversion to an easy-to-maintain accident handling mode.

[0064] This synergy allows the ultra-thin silicon steel cold rolling production system to combine the high rigidity advantage of the Sendkimir mill with the large opening advantage of the six-roll mill, and successfully break through the minimum rollable thickness limit of ultra-thin silicon steel. At the same time, it solves the industry problem of strip breakage treatment, which is something that no single type of rolling mill can achieve.

[0065] Specifically, please refer toFigure 2 The ultra-thin silicon steel cold rolling production system includes archway A and tower-shaped roll system.

[0066] The tower-shaped roll system consists of an upper roll system B and a lower roll system C. Both the upper roll system B and the lower roll system C are installed inside the archway A, and both the upper roll system B and the lower roll system C are tower-shaped roll systems. The structures of the upper roll system B and the lower roll system C are basically symmetrical. The arrangement of the tower-shaped roll system greatly improves the overall rigidity, so it can maintain a very small equipment bounce value when subjected to huge rolling pressure. Moreover, this arrangement allows for a smaller work roll diameter.

[0067] Please continue reading. Figure 2 Both the upper roll system B and the lower roll system C consist of ten rolls arranged in a tower shape. The innermost ring is the work roll used to contact the extremely thin silicon steel strip, and the outermost ring is the support roll.

[0068] The diameter of the work roll is 79-81mm to reduce the contact arc length of the work roll during rolling deformation.

[0069] In some embodiments, the diameter of the work roll is 80 mm, or about 80 mm. The size of the work roll that is in direct contact with the ultra-thin silicon steel strip is set to about 80 mm. The smaller diameter allows the contact arc length of the roll during rolling deformation to be smaller and greatly reduces the deformation resistance required for strip thinning.

[0070] Small work roll diameter and high roll system rigidity are among the decisive factors in breaking through the limit of rollable thickness of silicon steel. In this embodiment, the arrangement of the tower-shaped roll system satisfies the small roll diameter required for rolling ultra-thin silicon steel strip while ensuring the overall rigidity of the roll system.

[0071] The roll system rigidity of this embodiment is approximately five times that of a six-high rolling mill of the same specifications. The smaller work roll diameter reduces the elastic flattening of the corresponding rolls under immense rolling pressure. The tower-shaped arrangement of the upper roll system B and the lower roll system C improves the vertical stability of the work rolls that directly contact the strip, and prevents lateral movement of the work rolls during high-tension rolling processes. Furthermore, this arrangement disperses lateral and vertical forces to the corresponding equipment. This arrangement resolves the contradiction between small work roll diameter and large roll system rigidity, and provides the equipment foundation for successfully breaking through the minimum rollable thickness of silicon steel.

[0072] The support roller includes at least a mandrel, on which multiple thick-walled bearings are mounted. Specifically, the mandrel holds multiple thick-walled bearings together, and the outer rings of the thick-walled bearings directly act as the support roller, such as... Figure 5 As shown. The reason for adopting this arrangement is that the width of a single thick-walled bearing is not large, thus its stiffness is relatively large.

[0073] The outermost ring of the ten rolls consists of four support rolls arranged in a fan shape, with the center of the fan pointing towards the work roll. Each support roll includes at least a mandrel, on which multiple thick-walled bearings are mounted. The four support rolls arranged in a fan shape consist of two intermediate support rolls and two side support rolls. The two intermediate support rolls have the same number of thick-walled bearings, and the two side support rolls have the same number of thick-walled bearings, but the number of thick-walled bearings on the side support rolls differs from that on the intermediate support rolls by one. The difference in the number of thick-walled bearings on the side support rolls compared to the intermediate support rolls is mainly to prevent the gap between adjacent thick-walled bearings from indirectly affecting the strip surface and leaving a mark. The arrangement can be found in [reference needed]. Figure 5 , Figure 5 This shows that the gaps between the thick-walled bearings of the intermediate support roller (e.g., B3) and the side support roller (e.g., B4) within the same roller system (upper roller system B or lower roller system C) are staggered, that is, the gap between two adjacent thick-walled bearings on the intermediate support roller B3 is directly opposite to the outer surface of the thick-walled bearing of the side support roller B4.

[0074] by Figure 4 Taking the upper roller system B as an example, its outermost four support rollers are numbered B1-B4 clockwise. The number of thick-walled bearings on the middle support rollers B2 and B3 is the same, both being a positive integer n. Figure 5 The intermediate support rollers B2 and B3 each have 8 thick-walled bearings, i.e., n=8. The side support rollers B1 and B4 have the same number of thick-walled bearings, which are either positive integers n-1 or n+1. Figure 5 The number of thick-walled bearings in the side support rollers B1 and B4 is 7, that is, n-1=7, or it can be n+1=9.

[0075] by Figure 4 Taking the lower roller system C as an example, its outermost four support rollers are numbered C1-C4 in a counterclockwise direction. The number of thick-walled bearings in the middle support rollers C2 and C3 is the same, both being a positive integer m. Figure 5 The intermediate support rollers C2 and C3 each have 7 thick-walled bearings, i.e., m=7. The side support rollers C1 and C4 have the same number of thick-walled bearings, which are both positive integers m+1 or m-1. Figure 5 The number of thick-walled bearings in the side support rollers C1 and C4 is 8, that is, m+1=8, or m-1=6.

[0076] It is worth mentioning that m=n, or mn=±1.

[0077] In other words, in order to prevent the gap between adjacent thick-walled bearings from being indirectly transmitted to the belt surface and leaving a mark, in this embodiment, the number of thick-walled bearings of the intermediate support rollers in the same roller system is required to differ from the number of thick-walled bearings of the side support rollers by one.

[0078] To further address the strip branding issue, this embodiment provides two roller system configurations based on the strip width. Since the shape issue is more pronounced in wide strips, an asymmetrical roller system configuration is typically used for wider strips, while a symmetrical roller system configuration is typically used for narrower strips. Here, "wide strip" and "narrow strip" are relative terms, without specific numerical requirements.

[0079] Asymmetrical roller configuration specifically refers to the following: the number of thick-walled bearings on the intermediate support rollers of the upper and lower roller systems are different (i.e., mn=±1). For example, the upper roller system has 8 thick-walled bearings on the intermediate support rollers and 7 thick-walled bearings on each side support roller of the upper roller system. The lower roller system has 7 thick-walled bearings on the intermediate support rollers and 8 thick-walled bearings on each side support roller of the lower roller system. In this example, B2=B3=C1=C4=8, where B2, B3, C1, and C4 refer to the number of thick-walled bearings on the corresponding support rollers. B1=B4=C2=C3=7, where B1, B4, C2, and C3 refer to the number of thick-walled bearings on the corresponding support rollers. That is, the number of thick-walled bearings on the intermediate support roller B2, intermediate support roller B3, side support roller C1 and side support roller C4 is 8 each, and the number of thick-walled bearings on the side support roller B1, side support roller B4, intermediate support roller C2 and intermediate support roller C3 is 7 each.

[0080] A symmetrical roller system configuration specifically refers to the following: the number of thick-walled bearings on the intermediate support rollers of the upper and lower roller systems is the same (i.e., m=n), while the number of thick-walled bearings on the intermediate support rollers is one more or one less than the number of thick-walled bearings on the two side support rollers. For example, the number of thick-walled bearings on the intermediate support rollers of both the upper and lower roller systems is 8 (i.e., B2=B3=C2=C3=8, where B2, B3, C2, and C3 refer to the number of thick-walled bearings on the corresponding support rollers), while the number of thick-walled bearings on the two side support rollers of the same roller system is 7 or 9 (i.e., B1=B4=C1=C4=7, or B1=B4=C1=C4=9, or B1=B4=7 and C1=C4=9, or B1=B4=9 and C1=C4=7, where B1, B4, C1, and C4 refer to the number of thick-walled bearings on the corresponding support rollers).

[0081] It should be noted that, considering the different equipment space required for strips of different widths, this embodiment proposes a thick-walled bearing configuration scheme from another perspective: the upper roller system and the lower roller system can adopt the same or different thick-walled bearing configuration schemes.

[0082] The same thick-walled bearing configuration means that the number of thick-walled bearings in the middle of the upper roller system equals the number of thick-walled bearings in the middle support rollers of the lower roller system, and the number of thick-walled bearings in the side support rollers of the upper roller system equals the number of thick-walled bearings in the side support rollers of the lower roller system. Different thick-walled bearing configurations include asymmetrical roller system configurations, and also include situations where the number of thick-walled bearings in the middle of the upper roller system equals the number of thick-walled bearings in the middle support rollers of the lower roller system, while the number of thick-walled bearings in the side support rollers of the upper roller system and the number of thick-walled bearings in the side support rollers of the lower roller system are different. For example, the number of thick-walled bearings in the middle of the upper roller system equals the number of thick-walled bearings in the middle support rollers of the lower roller system, which is 8, but the number of thick-walled bearings in the side support rollers of the upper roller system is 7, and the number of thick-walled bearings in the side support rollers of the lower roller system is 9.

[0083] Because wide strips require more equipment space, they can accommodate asymmetrical roller configurations, allowing for different thick-walled bearing configurations.

[0084] The number of thick-walled bearings on the intermediate support rolls of the same roll system differs from the number of thick-walled bearings on the two side support rolls by one. This arrangement can ensure the stability of the equipment in both the transverse and vertical directions to ensure the continuous rolling process. At the same time, it can compensate for the influence of the axial discrete area between the thick-walled bearings on the strip, weaken the strip stress distribution along the width direction of the strip, and improve the strip shape and microstructure properties.

[0085] The ultra-thin silicon steel cold rolling production system also includes servo cylinder D; please refer to [link / reference]. Figure 2 or Figure 3 Servo cylinder D is located below the lower roll system C. Servo cylinder D controls the overall lifting and lowering of the lower roll system C to change the mill opening. The mill opening is suitable for the strip rolling of ultra-thin silicon steel, strip breakage treatment, and residue cleaning.

[0086] That is, the overall lifting of the lower roller system C is driven by the servo cylinder D. The lifting distance has a direct impact on the roller gap size and product thickness, and its guiding accuracy is guaranteed by the operating side frame 1 and the transmission side frame 2.

[0087] The overall lifting and lowering of the lower roller system C is driven by the servo cylinder D, which meets the requirements for large openings during threading, maintenance, and other situations. This allows the mill opening in this embodiment to reach 90mm, which is about 12 times that of a Sendkimir mill of the same specification. The larger opening provides convenience for threading thinner silicon steel. This arrangement specifically solves the problem of broken strips and cleaning of hard and brittle silicon steel. Combined with the large internal space, it allows for convenient cleaning of fragmented broken strip residues and avoids bearing burnout caused by incomplete residue cleaning.

[0088] The upper roller system B can be lifted as a whole, and has ten built-in rollers, of which the upper working roller has a diameter of about 80mm.

[0089] During rolling production, the upper roll system B is in a locked state. During non-rolling production, the lifting height of the upper roll system B is adjusted to keep the rolling line in a preset position. Non-rolling production includes roll replacement, rolling line calibration, or re-grinding of rolls.

[0090] That is, the upper roll system B is locked during normal production and is only adjusted when the rolls are replaced, the rolling line is calibrated, or the rolls are re-grinded to keep the rolling line in a fixed position.

[0091] Please see Figure 3 The frame A of the ultra-thin silicon steel cold rolling production system includes at least an operating side frame 1 and a drive side frame 2, both of which are made of cast steel. The operating side frame 1 and drive side frame 2, both machined from cast steel, are the main units bearing the rolling pressure.

[0092] Please continue reading. Figure 3 The archway A also includes two crossbeams installed between the operating side frame 1 and the transmission side frame 2, namely the upper crossbeam 3 and the lower crossbeam 4. The archway A is assembled from two frames and two crossbeams to reduce the processing difficulty and manufacturing cycle of individual components, and to facilitate its inspection and testing.

[0093] The extension and retraction of the servo cylinder D allows the lower roller system C to tilt along either the operating side or the transmission side, thereby eliminating wedge-shaped plates and controlling the same-plate difference of the first strip within ±3µm. The operating side is the side where the operating side frame 1 is located, and the transmission side is the side where the transmission side frame 2 is located. Ultra-thin silicon steel refers to a straight target strip that does not exhibit wedge-shaped plates.

[0094] Specifically, the servo cylinder D is located within the operating side frame 1 and the transmission side frame 2, and its position control accuracy is ±0.5µm. The servo cylinder D is a core component of the thickness control system, and its response speed, accuracy, and synchronization directly affect the roll gap, thus directly determining the product's thickness variation and quality. By controlling the extension and retraction of the servo cylinder D, the lower roll system C can be tilted along the operating side or transmission side. This function effectively controls the wedge shape and greatly improves the thickness variation within the same plate, thereby directly affecting key indicators such as the lamination coefficient of silicon steel products.

[0095] This invention has developed a comprehensive process flow that may affect the quality of silicon steel, and proposed a cold rolling method for ultra-thin silicon steel, dividing it into a material preparation stage and a cold rolling stage. Quantitative analysis was completed on numerous process parameters in the five stages of the material preparation stage: smelting, casting, hot rolling, normalizing, and pickling, providing a foundation for ensuring product quality. In the cold rolling stage, through the development of a high-tension rolling process and the precise control of oil temperature and quantity, the minimum rollable thickness limit was broken, achieving high requirements for same-plate thickness variation.

[0096] Based on the technological characteristics of the aforementioned ultra-thin silicon steel cold rolling method, an ultra-thin silicon steel cold rolling system with both large opening and high roll system rigidity was developed. The arrangement of the tower-shaped roll system satisfies the small roll diameter required for rolling ultra-thin silicon steel strip while ensuring overall roll system rigidity. The overall lifting and lowering of the roll system, driven by servo cylinders, meets the requirements for large opening during strip threading and maintenance, and the large internal space provides convenience for handling accidents such as strip breakage.

[0097] Those skilled in the art will understand that the above embodiments are specific examples of implementing the present invention, and in practical applications, various changes in form and detail may be made without departing from the spirit and scope of the present invention.

Claims

1. A cold rolling method for ultra-thin silicon steel, characterized in that, include: Step 100, Material Preparation Stage; Obtain raw materials and process them according to the steps of smelting, casting, hot rolling, normalizing and pickling to obtain the first strip. Step 200, cold rolling stage; During the cold rolling stage, the reduction rate, lubrication parameters, tensile stress, and sheet thickness are adjusted to thin the first strip, and the sheet thickness of the thinned first strip is controlled within ±3µm to obtain the target strip.

2. The method for cold rolling ultra-thin silicon steel according to claim 1, characterized in that, The smelting steps include: in the smelting process, controlling the silicon element mass fraction of the raw material to be 3.4%-3.6% to reduce iron loss and maintain ferromagnetic properties, thereby obtaining a cast billet.

3. The method for cold rolling ultra-thin silicon steel according to claim 2, characterized in that, The casting steps include: using a continuous casting process to slowly cool and heat-hold the billet to prevent the formation of hidden cracks and coarse grains.

4. The method for cold rolling ultra-thin silicon steel according to claim 3, characterized in that, The hot rolling step includes: Adjust the heating temperature to 1250-1350 degrees Celsius to control the degree of solid solution of the inhibitor in the billet; Adjust the final rolling temperature to 850-950 degrees Celsius to control the precipitation of inhibitors in the billet; Adjust the winding temperature to 550-650 degrees Celsius to control the formation of iron oxide scale.

5. The method for cold rolling ultra-thin silicon steel according to claim 4, characterized in that, The normalizing step includes: controlling the normalizing temperature to 1000-1100 degrees Celsius, holding the temperature for 2-3 minutes, and spraying water for rapid cooling to improve magnetism and reduce iron loss, thereby obtaining hot-rolled strip.

6. The method for cold rolling ultra-thin silicon steel according to claim 5, characterized in that, The pickling process includes a shot peening pretreatment step and a formal pickling step. In the shot peening pretreatment stage, the shot peening flow rate is 800-1000 kg / min, and the shot peening particles are 1.0 mm steel particles. The shot peening is used to remove the iron oxide scale on the surface of the hot-rolled strip. In the formal pickling process, hydrochloric acid is selected as the acid solution, with a mass fraction of 3% and a pickling temperature of 75 degrees Celsius, to obtain the first strip.

7. The method for cold rolling ultra-thin silicon steel according to claim 1, characterized in that, In the cold rolling stage, the reduction rate, lubrication parameters, tensile stress, and sheet thickness are adjusted to thin the first strip, and the sheet thickness of the thinned first strip is controlled within ±3µm to obtain the target strip. This includes the following steps: Maintain a reduction rate of over 85% to generate a large amount of deformation heat; The temperature of the lubricating medium is controlled at 55 degrees Celsius and the lubricating oil volume is 12000 ml / min. The high oil temperature and low oil volume lubrication scheme minimizes the heat carried away by the lubricating medium from the first strip. Adjust the tensile stress of the first strip to 40% of the yield strength of the current pass; The first strip is introduced into the ultra-thin silicon steel cold rolling production system. The ultra-thin silicon steel cold rolling production system is used to eliminate the wedge shape and control the same plate difference of the thinned first strip within the range of ±3µm to obtain the target strip.

8. The method for cold rolling ultra-thin silicon steel according to claim 7, characterized in that, The ultra-thin silicon steel cold rolling production system includes: Archway (A); The tower-shaped roller system consists of an upper roller system (B) and a lower roller system (C), both of which are installed inside the archway (A). A servo cylinder (D) is located below the lower roll system (C). The servo cylinder (D) controls the overall lifting and lowering of the lower roll system (C) to change the mill opening. The mill opening is suitable for the strip rolling of ultra-thin silicon steel, strip breakage treatment, and residue cleaning.

9. The method for cold rolling ultra-thin silicon steel according to claim 8, characterized in that, Both the upper roller system (B) and the lower roller system (C) consist of ten rollers; The ten rolls are arranged in a tower shape, with the innermost ring being the work rolls and the outermost ring being the support rolls; There are four support rollers; The four support rollers are arranged in a fan shape, with the center of the fan pointing towards the working roller; Each of the support rollers includes at least a mandrel on which a plurality of thick-walled bearings are fitted. The four support rollers arranged in a fan shape consist of two intermediate support rollers and two side support rollers. The two intermediate support rollers have the same number of thick-walled bearings, and the two side support rollers have the same number of thick-walled bearings. However, the number of thick-walled bearings on the side support rollers differs from the number of thick-walled bearings on the intermediate support rollers by one.

10. The method for cold rolling ultra-thin silicon steel according to claim 8, characterized in that, The upper roller system (B) can be raised and lowered as a whole; During rolling production, the upper roll system (B) is in a locked state; During non-rolling production, the lifting height of the upper roller system (B) is adjusted to keep the rolling line in a preset position. Non-rolling production includes roller replacement, rolling line calibration, or re-grinding of rollers. The archway (A) includes at least an operating side frame (1) and a transmission side frame (2). The extension and retraction of the servo cylinder (D) can make the lower roller system (C) tilted along the operating side or the transmission side to eliminate the wedge shape and control the same plate difference of the first strip within ±3µm. The operating side is the side where the operating side frame (1) is located, and the transmission side is the side where the transmission side frame (2) is located.

Images