Creep correction method for magnesium alloy thin-walled cylinder

Abstract

The invention provides a magnesium alloy thin-walled cylinder creep correction method which comprises the following steps: (1) heating a magnesium alloy thin-walled cylinder to reach a creep correction temperature; the creep correction temperature is 150 to 300 DEG C; (2) the magnesium alloy thin-walled cylinder is placed in a forming die to be subjected to tool positioning treatment, and first stress is applied to the surface of the magnesium alloy thin-walled cylinder; and (3) forming the magnesium alloy thin-walled cylinder within preset time under the action of the creep shaping temperature and the first stress to obtain the shaped magnesium alloy thin-walled cylinder, and cooling the shaped magnesium alloy thin-walled cylinder. According to the magnesium alloy thin-wall barrel creep deformation correcting method, the defect of uneven deformation caused by stress concentration and temperature difference in a traditional forming method is overcome by accurately controlling the temperature and the stress, and the forming precision and the surface quality of a magnesium alloy thin-wall barrel part are remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of hot forming of magnesium alloys, and particularly to a creep straightening method for thin-walled magnesium alloy cylinders. Background Art

[0002] Magnesium alloys have excellent specific strength and specific stiffness, and thus are widely used in the manufacturing of aerospace, automotive, and lightweight structural components. However, due to the low plasticity of magnesium alloys, especially in the forming process of complex shapes such as cylindrical parts and thin-walled parts with ribs, problems such as poor forming accuracy, uneven deformation, poor surface quality, and severe die wear often occur.

[0003] Traditional magnesium alloy forming methods, such as hot extrusion, although can be used to manufacture cylindrical parts, still have the following major technical problems when dealing with thin-walled or complex-shaped cylindrical parts: (1) inaccurate temperature control: during hot forming, uneven temperature distribution will lead to uneven stress distribution inside the alloy, resulting in uneven deformation during the forming of cylindrical parts, and even cracks or defects. (2) uneven deformation: when traditional hot forming methods are used to process thin-walled magnesium alloy cylindrical parts, stress concentration is likely to occur in some parts, leading to local excessive deformation or uneven wall thickness, and it is difficult to meet the high-precision requirements. (3) poor surface quality after forming: during traditional hot forming, the surface of magnesium alloys is prone to defects such as oxidation, scratches, and sticking to the die, affecting the appearance and subsequent processing performance of the product.

[0004] Therefore, how to improve the forming accuracy of magnesium alloy cylindrical parts, optimize temperature control, reduce defects, and improve production efficiency is an urgent problem to be solved at present. Summary of the Invention

[0005] The main object of the present invention is to provide a creep straightening method for thin-walled magnesium alloy cylinders to solve the problems of low accuracy, uneven deformation, and poor surface quality existing in traditional forming methods, eliminate the warping deformation of parts, reduce the internal stress of components and make the internal stress distribution uniform, and keep the shape and properties of components stable during subsequent use.

[0006] To achieve the above object, the present invention provides a creep straightening method for thin-walled magnesium alloy cylinders, including the following steps: (1) Heat-treat the thin-walled magnesium alloy cylinder to be straightened to reach the creep straightening temperature; the creep straightening temperature is 150 - 300 °C; (2) Place the thin-walled magnesium alloy cylinder to be straightened in a forming die for tooling positioning, and apply a first stress on the surface of the thin-walled magnesium alloy cylinder to be straightened; (3) Under the action of the creep straightening temperature and the first stress, form the thin-walled magnesium alloy cylinder to be straightened within a predetermined time to obtain a straightened thin-walled magnesium alloy cylinder, and cool the straightened thin-walled magnesium alloy cylinder; Among them, in step (1), the conditions of the heat treatment are controlled so that the temperature difference between the surface and the inside of the magnesium alloy thin-walled cylinder to be shape-corrected is not greater than 5 °C. In step (2), the conditions for applying the first stress are controlled so that the magnesium alloy thin-walled cylinder to be shape-corrected is in the elastic deformation stage.

[0007] Further, in step (1), the temperature during the heating process is controlled so that the temperature difference between the surface and the inside of the magnesium alloy thin-walled cylinder to be shape-corrected is not greater than 3 °C.

[0008] Further, in step (1), the method further includes: after heating the magnesium alloy thin-walled cylinder to be shape-corrected to the creep shape-correction temperature, holding for 5 - 30 min.

[0009] Further, in step (1), the conditions of the heat treatment further include: the heating rate is 1 - 50 °C / min.

[0010] Preferably, in step (1), the method includes: at least 3 temperature sensors are arranged on the inner and outer surfaces of the magnesium alloy thin-walled cylinder to be shape-corrected, and the heat treatment is carried out by electric pulse or resistance wire.

[0011] Further, in step (2), the tooling positioning treatment includes: sleeving the magnesium alloy thin-walled cylinder to be shape-corrected on the steel mold sleeve of the forming die, and arranging silica gel or a shape-correction die inside the magnesium alloy thin-walled cylinder to be shape-corrected, and the magnesium alloy thin-walled cylinder to be shape-corrected and the steel mold sleeve are in clearance fit at room temperature.

[0012] Further, in step (2), the first stress is 40 - 100 MPa.

[0013] Preferably, in step (2), the method includes: at least 3 stress sensors are uniformly arranged on the inner and outer surfaces of the magnesium alloy thin-walled cylinder to be shape-corrected, and the application method of the first stress is selected from at least one of multi-point pressurization, annular pressurization, and vacuum pressurization.

[0014] Further, in step (3), the predetermined time is 10 - 24 hours.

[0015] Further, in step (3), the cooling method includes: cooling the shape-corrected magnesium alloy thin-walled cylinder through water cooling or air cooling until it reaches room temperature.

[0016] The beneficial effects of the present invention are as follows: The creep straightening method for the thin-walled magnesium alloy cylinder provided by the present invention, on the one hand, by precisely controlling the surface and internal temperature uniformity of the thin-walled magnesium alloy cylinder, avoiding excessive local temperature differences, and reasonably controlling the forming temperature, it can also significantly reduce surface defects such as oxidation and scratches, and improve the surface quality of the thin-walled cylinder; on the other hand, through the cooperation of the forming die and the first stress, a uniform stress loading is obtained on the surface of the thin-walled magnesium alloy cylinder, thus effectively avoiding the defect of uneven deformation caused by stress concentration and temperature difference in the traditional forming method. It can be seen that the straightening method provided by the present invention can significantly improve the forming accuracy and surface quality of the thin-walled magnesium alloy cylindrical parts.

[0017] The method of the present invention can effectively shorten the production cycle, improve production efficiency, and at the same time ensure the consistency and stability of the product. Brief Description of the Drawings

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the structures shown in these drawings.

[0019] Figure 1 It is the tooling positioning diagram of the thin-walled magnesium alloy cylinder provided by the present invention in the forming die.

[0020] The realization, functional characteristics and advantages of the object of the present invention will be further described in conjunction with the embodiments with reference to the drawings. Detailed Embodiments

[0021] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of 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.

[0022] In addition, in the present invention, descriptions such as "first" and "second" are only for descriptive purposes, and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one of such features.

[0023] Moreover, the technical solutions between various embodiments of the present invention can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement it. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0024] The present invention provides a creep straightening method for a magnesium alloy thin-walled cylinder, comprising the following steps: (1) Heating the magnesium alloy thin-walled cylinder to be straightened to reach the creep straightening temperature; the creep straightening temperature is 150 - 300 °C; (2) Positioning the magnesium alloy thin-walled cylinder to be straightened in a forming die for tooling positioning, and applying a first stress on the surface of the magnesium alloy thin-walled cylinder to be straightened; (3) Under the action of the creep straightening temperature and the first stress, forming the magnesium alloy thin-walled cylinder to be straightened within a predetermined time to obtain a straightened magnesium alloy thin-walled cylinder, and cooling the straightened magnesium alloy thin-walled cylinder; Wherein, in step (1), controlling the conditions of the heating treatment so that the temperature difference between the surface and the inside of the magnesium alloy thin-walled cylinder to be straightened is not greater than 5 °C; In step (2), controlling the conditions for applying the first stress so that the magnesium alloy thin-walled cylinder to be straightened is in the elastic deformation stage.

[0025] According to the forming characteristics of different magnesium alloy materials, the present invention can appropriately adjust the creep straightening temperature range to ensure that the magnesium alloy is in a good creep straightening state. When the creep straightening temperature is too high, the precipitation rate of the precipitated phase is too fast, the precipitated phase coarsens, and the surface of the thin-walled part oxidizes, resulting in a decrease in the strength, toughness and surface quality of the component; while when the creep straightening temperature is too low, the dislocation movement ability decreases, resulting in local dislocation pile-up and stress concentration inside the component, and even crack initiation, thereby reducing the mechanical properties of the component. The inventor of the present invention has found through research that by setting the creep straightening temperature of the magnesium alloy thin-walled cylinder adopted in the present invention in the range of 150 - 300 °C, the magnesium alloy component undergoes stress relaxation at high temperature, the morphology of the precipitated phase is improved, the surface defects such as oxidation and scratches of the magnesium alloy thin-walled cylinder are greatly improved, and the surface quality of the magnesium alloy thin-walled cylinder is improved.

[0026] By precisely controlling the temperature difference between the surface and the inside of the magnesium alloy thin-walled cylinder to be not greater than 5 °C, and at the same time making the magnesium alloy thin-walled cylinder to be straightened in the elastic deformation stage, the present invention can effectively avoid the defect of uneven deformation caused by stress concentration and temperature difference in the traditional forming method, thereby significantly improving the forming accuracy and surface quality of the magnesium alloy thin-walled cylinder.

[0027] According to a particularly preferred specific embodiment, in step (1), the temperature during the heating process is controlled so that the temperature difference between the surface and the interior of the magnesium alloy thin-walled cylinder to be shape-corrected is not greater than 3°C. The inventor found through research that by adopting this preferred specific embodiment, a magnesium alloy thin-walled cylinder with higher forming accuracy can be obtained through the shape-correction process of the present invention.

[0028] In some specific embodiments, in step (1), the method further includes: after heating the magnesium alloy thin-walled cylinder to be shape-corrected to the creep shape-correction temperature, holding for 5 - 30 min. The inventor found that heating the magnesium alloy thin-walled cylinder to the creep shape-correction temperature and holding at this temperature for 5 - 30 min can ensure that the temperature of the surface and the interior of the magnesium alloy thin-walled cylinder is more uniform.

[0029] According to a particularly preferred specific embodiment, in step (1), the method includes: at least 3 temperature sensors are arranged on the inner and outer surfaces of the magnesium alloy thin-walled cylinder to be shape-corrected, and the heating treatment is carried out by means of electric pulse or resistance wire.

[0030] It should be noted that in the present invention, by respectively arranging temperature sensors at multiple positions on the inner and outer surfaces of the magnesium alloy thin-walled cylinder to be shape-corrected, the temperature distribution of the magnesium alloy thin-walled cylinder is monitored in real time, and temperature compensation is carried out by means of resistance wire or electric pulse heating, so as to achieve the purpose that the temperature difference between the surface and the interior of the magnesium alloy thin-walled cylinder to be shape-corrected is not greater than 5°C.

[0031] The present invention has no requirements for the types of the electric pulse or resistance wire, as long as precise temperature control can be achieved. On the basis of using the electric pulse or resistance wire, the present invention can also be equipped with a multi-point temperature monitoring device well-known to those skilled in the art, such as a thermocouple array, an infrared thermal imager, a multi-channel temperature data acquisition system, etc., so as to further ensure that the temperature difference between the surface and the interior of the cylindrical part does not exceed 3°C and avoid forming unevenness caused by temperature fluctuations.

[0032] As Figure 1 shown, according to a particularly preferred specific embodiment, in step (2), the tooling positioning process includes: sleeving the magnesium alloy thin-walled cylinder to be shape-corrected on the steel mold jacket of the forming mold, and arranging silica gel or a shape-correction mold inside the magnesium alloy thin-walled cylinder to be shape-corrected, and the magnesium alloy thin-walled cylinder to be shape-corrected and the steel mold jacket are in clearance fit at room temperature.

[0033] It should be noted that the present invention uses high-temperature and wear-resistant materials (such as alloy steel, cemented carbide, etc.) as the sizing die. At the same time, the die shape is designed to match the flow characteristics of the magnesium alloy. The contact surface between the steel die sleeve and the thin-walled magnesium alloy cylinder is coated with lubricants and anti-oxidation coatings well-known to those skilled in the art to reduce friction and material sticking to the die. The surface of the forming die is specially treated, such as improving the wear resistance of the steel die through carburizing, nitriding and other processes, enhancing its high-temperature resistance and anti-wear performance, and extending its service life.

[0034] In some specific embodiments, in step (2), the first stress is 40 - 100 MPa.

[0035] In some specific embodiments, in step (2), the loading rate of the first stress is 5 - 20 N / s.

[0036] In some specific embodiments, in step (2), the method includes: at least 3 stress sensors are evenly arranged on the inner and outer surfaces of the thin-walled magnesium alloy cylinder to be sized, and the application mode of the first stress is selected from at least one of multi-point pressurization, annular pressurization, and vacuum pressurization.

[0037] In order to make the surface stress distribution of the thin-walled magnesium alloy cylinder more uniform, the present invention evenly distributes stress sensors at multiple positions on the inner and outer surfaces of the thin-walled magnesium alloy cylinder. During the pressurization process, the stress distribution of the thin-walled magnesium alloy cylinder is collected in real time according to the distributed stress sensors, so that the stress is evenly distributed on the surface of the thin-walled part, avoiding the problems of local excessive deformation and cracks caused by stress concentration in the traditional method, and ensuring the uniformity during the forming process of the thin-walled part.

[0038] The inventor of the present invention found through research that by evenly arranging multiple stress sensors, and at the same time adopting the method of multi-point pressurization or annular pressurization or vacuum pressurization, in cooperation with the use of the forming die, a uniform pressure can be formed on the surface of the thin-walled magnesium alloy cylinder, further ensuring the shape accuracy of the thin-walled magnesium alloy cylinder during the entire forming process.

[0039] According to a particularly preferred specific embodiment, in step (3), the predetermined time is 10 - 24 hours.

[0040] It should be noted that during the forming process, the present invention arranges multiple arrays of thermocouples, stress sensors, strain sensors, etc. on the inner and outer surfaces of the thin-walled part to monitor key parameters such as creep sizing temperature, the first stress, and deformation in real time. Through data feedback and according to the Creep subroutine compiled by coupling the constitutive equation of the alloy component during creep forming, the heating temperature, pressure loading, and forming speed are automatically adjusted to ensure that the cylindrical part maintains the best state during the entire forming process.

[0041] According to a particularly preferred specific embodiment, in step (3), the cooling method includes: subjecting the shaped magnesium alloy thin-walled cylinder to water cooling or air cooling until it reaches room temperature.

[0042] It should be noted that after forming, the present invention controls the cooling rate by water cooling or air cooling to avoid internal stress or warping deformation caused by uneven cooling, ensure uniform temperature reduction of the magnesium alloy thin-walled cylinder during cooling, maintain stable dimensions and shape, and further improve the surface quality of the cylinder.

[0043] The creep shaping method for magnesium alloy thin-walled cylinders provided by the present invention can effectively shorten the production cycle, improve production efficiency, and at the same time ensure the consistency and stability of products.

[0044] In the present invention, the magnesium alloy thin-walled cylinders are mainly applied in fields such as aerospace, automotive, electronics, and lightweight structures. However, the present invention does not particularly limit the types of magnesium alloy materials in the magnesium alloy thin-walled cylinders, and magnesium alloys well-known to those skilled in the art can be used. In some specific embodiments, the magnesium alloy material in the magnesium alloy thin-walled cylinder can be selected from at least one of Mg-4Al-2Zn magnesium alloy, Mg-7.5Gd-1.5Y-0.4Zr magnesium alloy, and ZM6 magnesium alloy.

[0045] It should be noted that the above-mentioned magnesium alloys used in the present invention can be obtained through commercial purchase or prepared by conventional methods. Exemplarily, the preparation method of the Mg-7.5Gd-1.5Y-0.4Zr magnesium alloy includes the following steps: adding pure magnesium ingot blanks to an electric resistance furnace. After the magnesium ingots are completely melted and the furnace temperature rises to 700-800 °C, in SF 6 / CO 2 mixed gas (volume ratio of 1:99) and under the protection of MgCl 2 flux, successively add master alloys such as Mg-30Gd, Mg-30Y, Mg-30Nd, and Mg-30Zr to the melt; then introduce argon gas into the furnace body for refining and slag skimming. After standing for about 1 h, start pouring out magnesium alloy ingot blanks.

[0046] The present invention will be described in detail below through examples. In the following examples, unless otherwise specified, various raw materials and instruments used are commercially available products.

[0047] Example 1 This example provides a creep shaping method for magnesium alloy thin-walled cylinders. Among them, the type of magnesium alloy raw material is Mg-4Al-2Zn magnesium alloy; specifically, it includes the following steps: (1) Heat the solution-treated Mg-4Al-2Zn magnesium alloy thin-walled cylinder in an autoclave to 175 °C at a heating rate of 5 °C / min and hold at 175 °C for 30 minutes so that the temperature difference between the surface and the inside of the magnesium alloy thin-walled cylinder is not more than 3 °C. (2) Sleeve the magnesium alloy thin-walled cylinder to be calibrated on the steel mold sleeve of the forming die, and set silica gel inside the magnesium alloy thin-walled cylinder to be calibrated. The gap between the magnesium alloy thin-walled cylinder to be calibrated and the steel mold sleeve at room temperature is 1 mm. Then, use the mold to mechanically load a first stress of 70 MPa at a loading rate of 10 N / s to ensure that the geometric shape of the magnesium alloy thin-walled cylinder remains consistent. (3) Under the action of a creep calibration temperature of 175 °C and a first stress of 70 MPa, keep the temperature and load for 12 hours. Real-time monitor the temperature and the first stress through a temperature and stress sensor array, and use an automatic feedback control system to adjust the loading rate and temperature according to the monitored data to maintain the stability of the forming process. After forming, obtain the calibrated magnesium alloy thin-walled cylinder, and naturally cool the calibrated magnesium alloy thin-walled cylinder in the air to room temperature.

[0048] After creep calibration is completed, the dimensional accuracy of the Mg-4Al-2Zn magnesium alloy cylinder is significantly improved. After measurement by a coordinate measuring machine and a laser scanner, the dimensional accuracy of the magnesium alloy thin-walled cylinder is improved from the original 0.5 mm to 0.1 mm, meeting the requirements of high-precision manufacturing.

[0049] Example 2 This example provides a method for creep calibration of a magnesium alloy thin-walled cylinder, wherein the type of magnesium alloy raw material is Mg-7.5Gd-1.5Y-0.4Zr magnesium alloy; specifically, it includes the following steps: (1) Heat the surface-cleaned Mg-7.5Gd-1.5Y-0.4Zr magnesium alloy thin-walled cylinder in an autoclave to 200 °C at a heating rate of 5 °C / min and hold at 200 °C for 30 minutes so that the temperature difference between the surface and the inside of the magnesium alloy thin-walled cylinder is not more than 3 °C. (2) Set sealant around the forming die, sleeve the magnesium alloy thin-walled cylinder to be calibrated on the steel mold sleeve of the forming die, and lay a breathable felt, a vacuum bag, and silica gel on the inner surface of the magnesium alloy thin-walled cylinder respectively. The gap between the magnesium alloy thin-walled cylinder to be calibrated and the steel mold sleeve at room temperature is 0.5 mm. Then, apply a first stress of 100 MPa through vacuum pressure loading at a loading rate of 5 N / s to make the magnesium alloy thin-walled cylinder fit tightly with the die. (3) Under the action of the first stress of 200 °C and 100 MPa during creep straightening, keep the temperature and load for 21 hours. Use an infrared thermal imager, a laser scanner, and a stress sensor to monitor parameters such as temperature and the first stress in real time. Use an automatic feedback control system to adjust the loading rate and temperature according to the monitored data to maintain the stability of the forming process. After forming, obtain the straightened magnesium alloy thin-walled cylinder, and gradually cool the straightened magnesium alloy thin-walled cylinder in the air to room temperature naturally.

[0050] After completing creep straightening, the dimensional accuracy of the Mg-7.5Gd-1.5Y-0.4Zr magnesium alloy cylinder is significantly improved. Measured by a coordinate measuring machine and a laser scanner, the dimensional accuracy of the magnesium alloy thin-walled cylinder is improved from the original 1 mm to 0.5 mm, meeting the requirements of high-precision manufacturing.

[0051] Example 3 This example provides a method for creep straightening of a magnesium alloy thin-walled cylinder. Among them, the type of magnesium alloy raw material is ZM6 magnesium alloy, and the main components and their contents are: Nd 2.2 wt%, Zn 0.4 wt%, Zr 0.6 wt%, and the balance is magnesium; the specific steps are as follows: (1) Heat the end of the forged ZM6 magnesium alloy thin-walled cylinder to 200 °C by electric pulse medium, with a heating rate of 20 °C / min, and keep it at 200 °C for 10 minutes to ensure that the temperature difference between the surface and the inside of the magnesium alloy thin-walled cylinder does not exceed 3 °C; (2) Set the magnesium alloy thin-walled cylinder to be straightened on the steel mold jacket of the forming mold, and set silica gel inside the magnesium alloy thin-walled cylinder to be straightened. The gap between the magnesium alloy thin-walled cylinder to be straightened and the steel mold jacket at room temperature is 1 mm. Then use a multi-point pressurization system to apply a first stress of 50 MPa on the surface of the magnesium alloy thin-walled cylinder, and the loading rate of the first stress is 5 N / s to ensure that the geometric shape of the magnesium alloy thin-walled cylinder remains consistent; (3) Under the action of the first stress of 200 °C and 50 MPa during creep straightening, keep the temperature and load for 10 hours. Use a thermocouple and a stress sensor array to monitor temperature and the first stress in real time. Use an automatic feedback control system to adjust the loading rate and temperature according to the monitored data to maintain the stability of the forming process. After forming, obtain the straightened magnesium alloy thin-walled cylinder, and cool the straightened magnesium alloy thin-walled cylinder in the air to room temperature naturally.

[0052] After completing creep straightening, the dimensional accuracy of the ZM6 magnesium alloy thin-walled cylinder is significantly improved. Measured by a coordinate measuring machine and a laser scanner, the dimensional accuracy of the magnesium alloy thin-walled cylinder is improved from the original 2 mm to 0.4 mm, meeting the requirements of high-precision manufacturing.

[0053] Comparative Example 1 This comparative example provides a creep correction method for a magnesium alloy thin-walled cylinder. This method is carried out with reference to the method of Example 1, except that: in step (1), the temperature difference between the surface and the interior of the magnesium alloy thin-walled cylinder is 10 °C. Other process steps are the same as those in Example 1.

[0054] After creep correction is completed, the Mg-4Al-2Zn magnesium alloy cylinder is measured by a coordinate measuring machine and a laser scanner. The dimensional accuracy of the magnesium alloy thin-walled cylinder is 0.6 mm, which does not meet the requirements of high-precision manufacturing.

[0055] Comparative Example 2 This comparative example provides a creep correction method for a magnesium alloy thin-walled cylinder. This method is carried out with reference to the method of Example 1, except that: in step (2), the first stress is 150 MPa. Other process steps are the same as those in Example 1.

[0056] After creep correction is completed, the Mg-4Al-2Zn magnesium alloy cylinder is measured by a coordinate measuring machine and a laser scanner. The dimensional accuracy of the magnesium alloy thin-walled cylinder is 3 mm, which does not meet the requirements of high-precision manufacturing.

[0057] The creep correction method for the magnesium alloy thin-walled cylinder provided by the present invention, by precisely controlling the temperature, stress and cooling process, avoids the uneven deformation and defects caused by stress concentration and temperature difference in the traditional method, and can effectively improve the forming accuracy of the magnesium alloy thin-walled cylinder; by optimizing the forming temperature and cooling process, the occurrence of surface defects (such as oxidation, scratches, etc.) is significantly reduced, and the surface quality of the magnesium alloy thin-walled cylinder is improved. At the same time, the method of the present invention can also effectively shorten the production cycle, improve production efficiency, and ensure the consistency and stability of the product.

[0058] It should be noted that in this article, the terms "including", "comprising" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device.

[0059] In the above technical solution of the present invention, the above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention. Any equivalent structural transformation made under the technical concept of the present invention by using the content of the specification and drawings of the present invention, or directly / indirectly applied in other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. A creep correction method for a magnesium alloy thin-walled cylinder, characterized in that: The following steps are involved: (1) heating the magnesium alloy thin-walled cylinder to be shaped to reach a creep shaping temperature; the creep shaping temperature is 150-300°C; (2) placing the magnesium alloy thin-walled cylinder to be shaped into a forming die for tooling positioning, and then applying a first stress to the surface of the magnesium alloy thin-walled cylinder to be shaped; (3) forming the magnesium alloy thin-walled cylinder to be shaped within a predetermined time under the creep shaping temperature and the first stress to obtain a shaped magnesium alloy thin-walled cylinder, and cooling the shaped magnesium alloy thin-walled cylinder; Wherein, in step (1), the conditions of the heating treatment are controlled so that the temperature difference between the surface and the interior of the magnesium alloy thin-walled cylinder to be shaped is not greater than 5°C; In step (2), the forming die is adjusted and / or the conditions for applying the first stress are controlled so that the magnesium alloy thin-walled cylinder to be shaped is in an elastic deformation stage.

2. The creep correction method for a magnesium alloy thin-walled cylinder according to claim 1, characterized in that: In step (1), the temperature during the heating process is controlled so that the temperature difference between the surface and the interior of the magnesium alloy thin-walled cylinder to be shaped is not greater than 3°C.

3. The creep correction method for a magnesium alloy thin-walled cylinder according to claim 1, characterized in that: In step (1), the method further comprises: heating the magnesium alloy thin-walled cylinder to be shaped to a creep shaping temperature and then keeping the temperature for 5-30 minutes.

4. The creep correction method for a magnesium alloy thin-walled cylinder according to claim 1, characterized in that: In step (1), the conditions for the heating treatment also include: a heating rate of 1-50°C / min.

5. The creep correction method for a magnesium alloy thin-walled cylinder according to claim 4, characterized in that: In step (1), the method comprises: at least three temperature sensors are evenly arranged on the inner and outer surfaces of the magnesium alloy thin-walled cylinder to be shaped, and the heating treatment is performed by electric pulse or resistance wire.

6. The creep correction method for a magnesium alloy thin-walled cylinder according to claim 1, characterized in that: In step (2), the tooling positioning process includes: sleeve the magnesium alloy thin-walled cylinder to be shaped in the steel mold sleeve of the forming mold, and set a silicone or a shaping mold in the magnesium alloy thin-walled cylinder to be shaped, and the magnesium alloy thin-walled cylinder to be shaped and the steel mold sleeve are clearance-fitted at room temperature.

7. The creep correction method for a magnesium alloy thin-walled cylinder according to claim 1, characterized in that: In step (2), the first stress is 40-100 MPa.

8. The creep correction method for a magnesium alloy thin-walled cylinder according to claim 7, characterized in that: In step (2), the method comprises: at least three stress sensors are evenly arranged on the inner and outer surfaces of the magnesium alloy thin-walled cylinder to be shaped, and the first stress is applied in a manner selected from at least one of multi-point pressurization, annular pressurization and vacuum pressurization.

9. The creep correction method for a magnesium alloy thin-walled cylinder according to claim 1, characterized in that: In step (3), the predetermined time is 10-24 hours.

10. The creep correction method for a magnesium alloy thin-walled cylinder according to any one of claims 1 to 9, characterized in that: In step (3), the cooling method includes: cooling the shaped magnesium alloy thin-walled cylinder by water cooling or air cooling until it reaches room temperature.

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