Soft lining plate shape cooperative controlled rolling method for high-quality metal plate

Abstract

The invention provides a soft lining plate shape cooperative controlled rolling method for a high-quality metal plate. The method is characterized in that soft lining plates are additionally arranged on the two sides of a target metal plate, the contact state between the plate and a roller is changed, during rolling, the lining plates preferentially generate plastic deformation and can adjust distribution of force energy situation in a self-adaptive mode, microstructure optimization is achieved, and the uniform deformation coordination capacity of the plate is enhanced; in the rolling process, the soft lining plate can also achieve the effect of a lubricating pad, labor-saving load reduction and single-pass large-rolling-reduction rolling are achieved, and meanwhile the plastic forming limit of the metal plate can be improved; the defects of poor plate shape stability, easy deviation and the like caused by impact and stress fluctuation due to uneven surface or unstable movement caused by long-term work of the roller can be reduced or eliminated, the vibration of the rolling mill can be reduced, a certain buffering effect is achieved, and the service life of equipment and the roller is prolonged; the method is also suitable for forming and manufacturing of high-performance metal plates with large size specifications, low plasticity, difficult deformation and the like, and cooperative controlled rolling of the shape properties of the high-quality metal plates can be achieved efficiently with low consumption.

Description

Technical Field

[0001] The invention relates to the field of roll forming of metal plates, and in particular to a soft liner formability coordinated controlled roll forming method for high-quality metal plates. Background Art

[0002] Rolling is one of the most widely used forming and manufacturing methods for high-quality sheet products. It can meet the actual requirements of industrial production and is of great significance to the research and development of lightweight parts for high-end equipment in the fields of deep space exploration, large-scale transportation, cutting-edge weapons and civilian product manufacturing. However, when using traditional rolling methods, a multi-pass small reduction deformation mode is often used, and multiple intermediate heating and insulation processes are involved, which is not conducive to reducing energy consumption and production costs; a single pass with a large reduction will exert a large shear force on the sheet, which is easy to cause edge cracks.

[0003] Subsequently, special rolling methods such as cumulative rolling, cross rolling and hard liner controlled rolling have emerged and been applied. Among them, cumulative rolling is to degrease and work harden two metal plates of the same size, then roll the stacked plates, cut them in the middle, and repeat the rolling steps. Single-pass large reduction rolling can be achieved, but the rolling process is relatively cumbersome and complex, with high cost, and the oxide layer will be continuously introduced during rolling. As the number of rolling increases, the increase in the number of oxide layers will have an adverse effect on the comprehensive performance of the plate; cross rolling is to change the rolling direction after each or multiple rolling passes during the rolling process to significantly improve the anisotropy of the plate, improve corrosion resistance and reduce the base surface texture strength, so that its internal structure is more uniform, but the rolling process requires continuous shutdown to change direction, which significantly reduces production efficiency.

[0004] In response to the problems of low production efficiency and poor plate quality in traditional rolling methods, the invention patent with Chinese patent number ZL201410123706.7 and publication date August 6, 2014 discloses a method for rolling magnesium alloys with large reduction. This method adds hard lining plates to the upper and lower surfaces of the magnesium alloy and rolls them together with the target plate. While increasing the single-pass reduction during the magnesium alloy rolling process, it can also refine the grains and weaken the texture, providing an effective way to prepare high-performance magnesium alloy plates. In view of the deformation conditions and micro-configuration evolution of the slab during the liner rolling process, the invention patent with Chinese patent number ZL201710066892.9 and publication date May 31, 2017 discloses a method for preparing superplastic magnesium alloy by short-process rolling, which includes three steps: high rolling rate rolling, conventional rolling rate cooling rolling and heat treatment. By adding a hard liner, a large reduction rolling is achieved to prepare the magnesium alloy slab, thereby realizing the preparation of high-performance mixed crystal structure magnesium alloy sheet, ensuring that the magnesium alloy has good room temperature plasticity while having high strength. However, after adding the hard liner, the contact area between the hard liner and the sheet becomes larger, which has a great influence on the coordinated regulation of the sheet deformation behavior and organizational properties.

[0005] Focusing on the research and development of new methods for preparing high-performance metal sheets and new forming processes is not only a long-term goal in the strategic development plan of this field, but also a booster to solve the problems that restrict the rapid development of traditional metal sheet rolling forming technology and promote the doubling of the application of high value-added products. Summary of the invention

[0006] In order to solve the problem that traditional metal sheet rolling often uses small reduction and multiple passes to accumulate or increase energy consumption to achieve large deformation, ensure the dimensional accuracy and good quality of the rolled formed sheet, and realize the coordinated control of the shape of the metal sheet, the present invention provides a soft liner shape coordinated control rolling method for high-quality metal sheets, which is particularly suitable for the forming and manufacturing of low-plasticity and difficult-to-deform metal sheets. It is characterized in that: soft liner plates are added on both sides of the target metal sheet to change the contact state between the sheet and the roller, so that the interface contact condition changes from local rolling friction to overall sliding friction. According to actual needs, the structure and performance of the target metal sheet can be obtained, and the hardness, thickness and surface roughness of the soft liner plates on both sides of the sheet can be set to be the same / different. By changing the hardness, thickness and surface roughness, the distribution difference of the force-energy state during the rolling process can be controlled to achieve microstructure optimization, enhance the uniform deformation coordination ability of the sheet, and obtain a high-quality metal sheet.

[0007] The present invention is achieved through the following technical solutions: Step 1: Prepare two soft lining plates of the same size for mechanical cutting; Step 2: Grind the upper and lower surfaces of the metal plate and the outer surface of the soft lining plate until smooth, remove the oil stains with acetone solution, and then dry them; Step 3: Evenly spray the isolation agent on the contact surfaces of the two soft lining boards and the target board on both sides; Step 4: sequentially assemble the upper soft lining plate 2, the metal plate 4, and the lower soft lining plate 5, wherein the metal plate is sandwiched between the upper and lower soft lining plates; Step 5: preheat the sandwich structure of the soft lining plate and the metal plate in a heating furnace at a certain temperature for a holding time of t; Step 6: Adjust the reduction H of the conventional rolling mill. Driven by the conventional rolling mill, the metal sheet is fed into the rolling mill by the push block, and the soft liner will produce relatively large plastic deformation; Step 7: After rolling, the metal sheet is air-cooled to room temperature and corrected to ensure that the surface of the metal sheet is flat after rolling. Excess waste is cut on a shearing machine and annealing is performed.

[0008] Compared with the prior art, the method of the present invention has the following beneficial effects: 1. A soft lining plate with relatively low hardness and easy to deform is added to the outside of the target plate to be rolled. During the rolling process, the plate does not directly contact the roller, so the interface contact condition changes from rolling friction to sliding friction. The force applied by the roller is transmitted through the soft lining plate to cause the plate to undergo plastic deformation, changing from the direct force of the traditional rolling method to an indirect force state, and the loading method also changes from local to overall loading; 2. After adding the soft liner, the contact area with the target plate to be rolled is significantly increased, reducing the pressure per unit area, and achieving large reduction in a single pass. In addition, the soft liner also acts as a lubricating pad during the rolling process, which has a significant effect of saving effort and reducing load. It can be used not only for the forming and manufacturing of large-size and high-performance metal plates, but also for low-plasticity and difficult-to-deform metal plates; 3. The target plate and the liner are in direct contact in the normal direction, and there is a reaction force between the two. Because the hardness is lower than that of the target plate, the liner deforms first when the roller is pressurized, and the deformation is large. Therefore, during the rolling process, under the action of the liner clamping, the shape and size of the plate change in a linked manner. Compared with the traditional rolling method, soft liner rolling can significantly improve the plastic forming limit of the plate; Fourth, because the lining material is relatively soft and deforms first, the distribution of force and energy can be adjusted adaptively during the rolling process. This significantly enhances the uniform deformation coordination ability of the target plate, avoids the risk of excessive thinning or even cracking due to stress concentration in local areas, and significantly improves the plate shape and quality stability; 5. Due to the addition of soft lining, the stress state and deformation behavior of the plate during rolling change accordingly, which makes its grain size and distribution have certain differences, forming a mixed crystal structure with coarse / fine grains. The significant mechanical incompatibility of different grain size regions changes the plastic deformation mechanism of the plate, drives the activation of multiple deformation modes, plays a role in coordinating the load deformation capacity of the plate, and significantly improves the plastic forming and mechanical properties of the composite plate; 6. The soft lining plate is added between the plate and the roller, which can reduce or eliminate the defects such as poor plate shape stability and easy deviation caused by the impact and stress fluctuation caused by the long-term operation of the roller, the uneven surface or unstable movement. At the same time, it helps to reduce the vibration of the rolling mill, plays a certain buffering role, and prolongs the service life of the equipment and rollers; 7. In the traditional hot rolling process of metal plates, direct contact with the rollers and feeding into the gap between the rollers will cause the temperature of the plates to dissipate rapidly, deteriorating their forming properties. Adding a soft lining plate changes the stress state and deformation behavior of the plates, while avoiding direct contact with the rollers, playing a role in heat preservation, and significantly improving the forming ability and mechanical properties of the plates; 8. For close-packed hexagonal structure metals such as magnesium alloys, the number of slip systems that can be opened is far less than that of body-centered cubic and face-centered cubic structure metals, which are prone to generate strong basal surface textures, making subsequent deformation difficult. The addition of soft linings changes the grain morphology and orientation distribution characteristics of the plate, weakening the texture strength while also promoting the improvement of the forming performance, expanding the scope of application of metal plates; 9. Considering the constraints of factors such as bite conditions, when adding hard liner for rolling, the initial plate thickness should not be too large and a certain inclination angle should be prefabricated at the end of the composite plate (slab and liner) to facilitate smooth bite rolling. Due to the relatively small hardness, under the same conditions, soft liner rolling is also suitable for the forming of relatively thick plates, and no pretreatment is required, which simplifies the process flow and significantly improves production efficiency and performance. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 It is a schematic diagram of the experimental process of the present invention; Figure 2 It is a schematic diagram of the overall force of the rolled plate of the present invention; Figure 3 is a schematic diagram of the rolling device of the present invention; DETAILED DESCRIPTION

[0009] The design scheme of the present invention is described in detail below with reference to the accompanying drawings, which are only used to help understanding and cannot represent all the ideas of the invention.

[0010] Specific implementation method 1: Combined with the figure to illustrate this implementation method, this implementation method includes an upper roller 1, an upper soft lining plate 2, an isolation agent 3, a metal plate 4, a lower soft lining plate 5, and a lower roller 6. This implementation method is completed by the following steps: 1. Prepare a metal plate with a thickness of h1 and a hardness of m1. The thicknesses of the upper soft lining plate 2 and the lower soft lining plate 5 are h2 and h3 respectively, requiring h2=h3, and the hardness m2=m3; 2. Use acetone solution to remove the oil stains on the contact surface of the metal plate 4 and the upper and lower soft lining plates 2, 5 and then dry it; 3. The metal plate 4 is in contact with the upper and lower soft lining plates 2, 5 Spray an isolating agent on the surface; Fourth, clamp the metal sheet 4 between the upper and lower soft lining plates 2 and 5, place the sheet in the middle of the two soft lining plates, and wrap and fix the upper and lower lining plates with iron wire; Fifth, put the sandwich structure assembled in sequence into a heating furnace for preheating and keep warm for a period of time t; Sixth, adjust the pressure H of the traditional rolling mill, and send the sheet into the traditional rolling mill by the push block. During rolling, the soft lining plate and the metal sheet cooperate to undergo plastic deformation; Seventh, after rolling, the metal sheet is air-cooled to room temperature and corrected to ensure that the surface of the metal sheet is flat after rolling. After rolling, the rolled plate is cut on a shearing machine to remove excess waste and annealed.

[0011] Specific implementation method 2: The thickness of the upper soft lining plate 2 and the lower soft lining plate 5 are different, the thickness of the upper soft lining plate 2 is h2, the thickness of the lower soft lining plate 5 is h3, and it is required that h2≠h3; the remaining steps are the same as method 1.

[0012] Specific implementation method three: the friction coefficients of the upper soft lining plate 2 and the lower soft lining plate 5 are different, the friction coefficient of the upper soft lining plate 2 is μ1, and the friction coefficient of the lower soft lining plate 5 is μ2, requiring μ1≠μ2; the remaining steps are the same as method one.

[0013] Specific implementation method 4: The upper soft lining plate 2 and the lower soft lining plate 5 have different hardnesses, the hardness of the upper soft lining plate 2 is m2, and the hardness of the lower soft lining plate 5 is m3, requiring 0<m2≠m3<m1; the remaining steps are the same as method 1.

Claims

1. A method for coordinated controlled rolling of a soft lining plate of high-quality metal sheet, the specific steps of the method are as follows: Step 1, prepare two soft lining plates of the same size, whose hardness is about 0.3~0.8 times that of the rolled plate, and the metal plate with a length and width of l1×d1 and a thickness of h1; Step 2, polish the upper and lower soft lining plates and the contact surface of the metal plate surface to be smooth, and use acetone solution to remove the surface oil and then dry; Step 3, spray an isolation agent on the outer surface of the upper and lower soft lining plates and the contact surface of the metal plate; Step 4, sequentially combine them into an upper soft lining plate, a metal plate, The metal sheet is sandwiched between the upper and lower soft liners, and the upper and lower soft liners are fixed with iron wire; step five, the fixed composite structure is placed in a heating furnace for preheating at temperature T, and the insulation time is t; step six, the conventional rolling mill is adjusted to reduce the amount of H, and the metal sheet is sent into the conventional rolling mill by the push block. During the rolling process, the soft liner and the metal sheet are plastically deformed in coordination; step seven, after rolling, the metal sheet is air-cooled to room temperature and corrected to ensure that the surface of the metal sheet is flat after rolling, and the metal sheet is cut on a shearing machine to obtain the required sheet.

2. The method for controlling the shape of a soft liner plate of a high-quality metal sheet according to claim 1 is characterized in that: One of the soft lining plates can be replaced with a hard lining plate, so that the rolling forces on the upper and lower surfaces of the metal plate are different, so that the metal plate forms a mixed crystal structure in which coarse / fine grains of different grain sizes coexist, which has a strengthening effect on the alloy material.

3. The method for controlling the shape of a soft liner plate of a high-quality metal sheet according to claim 1 is characterized in that: The surface roughness of the upper and lower soft linings can be changed so that the metal sheet can obtain a mixed crystal structure with different organizational states, thereby overcoming the inverted strength-ductility relationship of the homogeneous material.

4. The method for controlling the shape of a soft liner plate of a high-quality metal sheet according to claim 1, characterized in that: During the rolling process, the metal sheet does not come into direct contact with the rollers. Instead, the force applied by the rollers is transmitted through the soft lining. The lining undergoes plastic deformation first, and the stress field distribution is adaptively adjusted to enhance the sheet's ability to coordinate uniform deformation, thus avoiding the risk of excessive thinning or even cracking of the sheet due to stress concentration.

5. The method for controlling the shape of a soft liner plate of a high-quality metal sheet according to claim 1, characterized in that: During the rolling process, under the action of the soft lining, the grain size and distribution characteristics of the metal plate change significantly, forming a mixed crystal structure with coarse / fine grains coexisting, improving the plastic deformation ability and mechanical properties of the plate, and developing excellent metal materials.

6. The method for controlling the shape of a soft liner plate of a high-quality metal plate according to claim 1, characterized in that: The application of soft lining acts as a lubricating pad, which can achieve large reduction rolling in a single pass and effectively reduce the pressure per unit area, thereby reducing or even eliminating the problem of poor plate shape stability caused by impact and stress fluctuations caused by uneven surface or unstable movement of the rollers caused by long-term operation; secondly, the soft lining can also reduce the rapid loss of plate temperature and improve the forming performance of the plate to achieve the preparation of high-performance, high-quality metal plates.

7. The method for controlling the shape of a soft liner plate of a high-quality metal plate according to claim 1, characterized in that: Metal plates of various thicknesses from thin plates to thick plates can be rolled. If the length and width of the metal plate are l1×d1 and the upper and lower soft lining plates have the same size and the length and width are l2×d2, then l2>l1 and d2>d1 must be required to ensure that the lining plate completely covers the metal plate and reduce the occurrence of edge cracks; and the thickness of the auxiliary soft lining plate can be adjusted to change the force exerted by the soft lining plate on the upper and lower surfaces of the metal plate, so that there is a difference in the force on both sides of the plate, resulting in changes in the size and direction of the upper and lower shear forces of the plate, effectively weakening the strong base surface texture and improving the anisotropy of the plate.

8. The method for controlling the shape of a soft liner plate of a high-quality metal plate according to claim 1, characterized in that: The thickness of the upper and lower soft lining plates can be adjusted h2≠h3, or the friction coefficient μ1≠μ2, or the hardness of the upper and lower soft lining plates can be adjusted to be different and both are smaller than the target plate hardness, that is, 0<m2≠m3<m1 to change the stress conditions and deformation behavior of the target metal plate, thereby realizing the preparation of high-performance plates with different microstructures, effectively achieving the synergistic improvement of the strength and ductility of the material, and significantly improving the forming performance of the plate.

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