Metal plate creep forming and annealing softening coupled shape correcting device and straightening method

Abstract

The invention discloses a plate creep forming and annealing softening coupled shape righting device and a straightening method.The method comprises the steps that firstly, softening curves of annealing of an aluminum alloy plate at different temperatures are obtained, and the softening annealing temperature and time at which the hardness reduction proportion does not exceed 5% are selected according to the softening condition; the metallographic structure before and after annealing and softening treatment is basically kept stable, so that the influence of shape correction on the product performance is reduced; according to the thickness of the plate, the initial bending degree and the annealing temperature, the reasonable downward-pressing arc radius is designed, the aluminum alloy plate is loaded on a shape correcting mold and is heated to the annealing temperature along with a furnace, and the aluminum alloy plate is under the loading condition lower than the yield stress in a short time; annealing softening and creep deformation occur synchronously in the process of keeping the loading force and the temperature. The aluminum alloy plate treated through the method is small in residual stress, the residual curvature of each section of the plate is uniform, and the influence on the performance of a plate product is small.

Description

Technical Field

[0001] The invention relates to a plate creep forming and annealing softening coupling orthopedic device and a straightening method, belonging to the device technology and nonferrous metal material processing engineering technology fields. Background Art

[0002] Alloy thin plates are often affected by other coupled energy fields such as stress fields and temperature fields during rolling, pre-stretching, heat treatment, cooling, machining, sandblasting / electroplating, and transportation. Under the influence of these energy fields, the plates inevitably have certain residual stresses, which will cause overall or local deformation of the plates, resulting in a significant decrease in the product qualification rate of thin metal plates. In order to keep the surface flatness of thin metal plates, the plates must be straightened on the straightening device. Thin plate bending and straightening technology is an important finishing process in the production process of aluminum alloy thin plates, which determines the quality and precision of the final product. The disadvantages of traditional straightening technology are: enterprises need to purchase special straightening equipment, such as multi-point bending mold straightening equipment, roller equipment, pressure straightening, etc. These professional equipment are also limited to a single plate size, resulting in an increase in the operating costs of the enterprise; residual stress is also difficult to avoid in the product after traditional pressure processing.

[0003] Therefore, designing a thin plate straightening device and straightening method with low cost, easy processing, high utilization rate, small residual stress and uniform residual curvature of the plate after straightening is an urgent problem to be solved. Summary of the invention

[0004] In view of the shortcomings of the prior art, the first object of the present invention is to provide a metal plate creep forming and annealing softening coupling correction device. The three-point bending straightening device provided by the present invention is simple in device, simple and controllable in operation, high in precision, and not limited by the size of the plate, and has the characteristics of low cost and high utilization rate.

[0005] The second purpose of the present invention is to provide a correction method for metal plates by coupling creep forming and annealing softening. The method provided by the present invention has the characteristics of low cost and high utilization rate. By controlling the annealing temperature, annealing holding time, deformation amount, etc., annealing softening and creep forming straightening under low stress are achieved to obtain a plate with low residual stress and uniform residual curvature.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] The present invention relates to a corrective device for coupling creep forming and annealing softening of a metal sheet, the corrective device comprising a straightening component and a supporting component, the straightening component comprising a manual driving component and an upper pressure rod, the manual driving component comprising a bolt and a reset spring, the bolt consisting of a head and a screw, the reset spring being sleeved on the lower end of the screw, the supporting component comprising a lower push rod A, a lower push rod B and a lower push rod fixing plate, a threaded hole being provided in the middle of the lower push rod fixing plate, the upper pressure rod and the lower push rod fixing plate being connected to the threaded hole through the screw, the upper pressure rod being provided with a through hole for the screw to pass through and cooperate with the reset spring to realize the up and down movement of the upper push rod, the lower push rod fixing plate being further provided with a plurality of circular arc grooves, the circular arc grooves being used to stabilize the lower push rod A and the lower push rod B, the lower push rod A and the lower push rod B being arranged in any two circular arc grooves symmetrically centered on the upper pressure rod.

[0008] The orthopedic device provided by the present invention provides pressure through the upper push rod and directly applies it to the surface of the metal plate during the loading process. The lower push rod A and the lower push rod B support the two ends of the metal plate. The metal plate bends under the action of the pressure of the upper push rod. The bending radius of the metal plate can be adjusted by adjusting the length of the screw screwed into the threaded hole to adjust the loading stress. During the orthopedic process, the above-mentioned orthopedic device and the metal plate can be placed in a heat treatment furnace to complete the orthopedic process and then taken out together. Subsequently, the length of the screw screwed into the threaded hole is adjusted and reduced until it reaches an appropriate position. At this time, the reset spring begins to reset and lift the upper push rod. The upper push rod unloads the pressure on the metal plate, so that the metal plate can be restored to a straight state so that it can be taken out from the mold, completing the reset and unloading process.

[0009] Conventional three-point bending devices often rely on universal testing machines to provide loading force and achieve reciprocating motion. The present invention directly realizes manual adjustment to provide loading force and reciprocating motion through the linkage of a simple reset spring and a screw rod, which greatly reduces the test cost and simplifies the assembly difficulty of the tooling mold. The small size of the device allows it to be used in conjunction with a heat treatment furnace. The intersecting fixed groove design facilitates the position adjustment of the upper and lower push rods to adapt to the correction of metal sheet materials of different specifications, thereby improving the universality of the device.

[0010] In a preferred solution, the lower push rod fixing plate is provided with two groups of threaded holes, any group of threaded holes contains two symmetrically distributed threaded holes, the connecting line of the two groups of threaded holes is vertical, and the upper pressure rod is provided with through holes corresponding to the two groups of threaded holes.

[0011] In a preferred solution, the arc grooves are distributed in both the transverse and longitudinal directions of the lower push rod fixing plate.

[0012] In the present invention, since a plurality of arc grooves are provided, the positions of the lower push rod A and the lower push rod B can be adjusted. Meanwhile, since two groups of vertical threaded holes and transverse and longitudinal arc grooves are provided, the upper pressure rod and the lower push rod A and the lower push rod B can be rotated 90 degrees according to the size of the plate for installation, thereby meeting the orthopedic requirements of plates of different sizes.

[0013] In a preferred solution, the bolt and the return spring are both symmetrically arranged in two positions. The return spring is arranged at two symmetrical positions, so that the user can manually rotate and adjust the downward pressing radius at different positions. At the same time, when the screw is unscrewed, the return spring pushes up the upper pressing rod to achieve reset.

[0014] Preferably, the manual drive assembly further comprises a gasket, and the gasket is arranged between the head of the bolt and the upper pressure rod.

[0015] In a preferred solution, the lower push rod A and the lower push rod B are cylinders of the same size. The lower push rod A and the lower push rod B of the same size are used to ensure that the force at both ends of the plate is evenly applied without deflection.

[0016] In a preferred solution, the radius of the through hole in the upper push rod is 1-1.5 mm larger than the outer diameter of the screw rod, so that each screw rod can be rotatably mounted on the lower push rod fixing plate.

[0017] Preferably, the outer diameter of the lower push rod A and the lower push rod B is 1-3 mm larger than the inner diameter of the arc groove. When the size is within this range, it is not only convenient to fix the lower push rod A and the lower push rod B, but also convenient to disassemble and install the lower push rods on the bottom plate fixing plate.

[0018] The present invention discloses a correction method for coupling creep forming and annealing softening of metal plates. The method adopts a sample of the same material as the metal plate to be corrected to measure the softening curve of the sample annealed at different temperatures, selects the temperature and time at which the hardness reduction ratio does not exceed 5% and the metallographic structure before and after the softening treatment remains stable as the annealing temperature and the holding time, and then calculates and obtains the required downward pressing arc radius R during correction. The metal plate to be corrected is loaded onto the correction device so that it is located above the lower push rod A and the lower push rod B and below the upper push rod. During loading, the position of the lower push rod is adjusted by bolts according to the downward pressing arc radius R. The correction device loaded with the metal plate to be corrected is placed in a heat treatment furnace. Annealing softening and creep deformation are synchronously performed at the above annealing temperature and holding time for correction. After correction is completed, the correction device is immediately cooled.

[0019] The calculation method of the downward pressing arc radius R is:

[0020] First, based on the relationship between the creep deformation stress and the yield stress of the metal sheet to be corrected, and the deformation caused by softening under annealing, the bending normal stress is set according to formula (1);

[0021] σ≤XYσ s Where Y is 0.1-0.5 Formula (1)

[0022] Where X is the coefficient of the relationship between the creep deformation stress and the yield stress of the metal sheet to be corrected, based on the coefficient of deformation caused by annealing softening;

[0023] Then, according to the relationship between bending normal stress and curvature, R is calculated according to formula (2):

[0024]

[0025] Wherein E is the elastic modulus of the metal sheet to be corrected, and y is the eccentric distance of the metal sheet to be corrected (the distance between the bent section of the metal sheet to be corrected and the farthest point of the metal sheet to be corrected).

[0026] By adopting the above method of the present invention, in the orthopedic process of the present invention, it can be ensured that the bending normal stress is below the yield stress. When the bending stress is adopted, the minimum curvature radius during the elastic bending process of the orthopedic metal sheet is obtained according to formula (3) to perform R min ,

[0027]

[0028] Where E in formula (3) is the elastic modulus of the orthopedic metal sheet, t is the thickness of the orthopedic metal sheet, σ s is the yield limit of the metal sheet at the orthopedic temperature;

[0029] The radius of the pressing arc R should be greater than R min If it is less than this value, the yield limit of the plate is exceeded and plastic deformation begins to occur, which causes a large amount of deformation of the plate, affecting the straightening effect. At the same time, the residual stress is high, which deviates from the original intention of straightening. According to the invention, σ≤XYσ s The σ calculation result obtained will not show R less than R min In the case where three-point bending is performed using R obtained by the calculation formula of the present invention, a loading stress lower than the yield stress is used to avoid the introduction of residual stress caused by plastic deformation.

[0030] In the present invention, formula (2) is derived from the following formula:

[0031] First, according to the equation of bending normal stress, equation (4):

[0032]

[0033] Where σ is the bending normal stress, M is the bending moment acting on the orthopedic metal sheet, y is the eccentric distance of the metal sheet to be orthopedic (the distance between the bent section of the metal sheet to be orthopedic and the farthest point of the metal sheet to be orthopedic), and I is the section inertia moment of the orthopedic metal sheet;

[0034] According to the equation relationship between bending moment and section inertia moment, equation (5)

[0035]

[0036] Then we can obtain formula (2).

[0037] The preferred solution is to use a sample of the same material as the metal plate to be corrected to measure the softening curve of the sample annealed at different temperatures and the creep aging treatment curve, and select the temperature and time at which the hardness reduction ratio does not exceed 5%, the metallographic structure before and after softening treatment remains stable, and the creep strain is less than 1% as the annealing temperature and holding time.

[0038] The preferred solution is σ=XYσ s .

[0039] Preferably, the material of the metal sheet is aluminum alloy

[0040] Further preferably, the material of the metal plate is 5 series aluminum alloy or 7 series aluminum alloy, the thickness of the metal plate is 0.3-2 mm; and the shape of the plate is rectangular.

[0041] Preferably, when the material of the metal sheet is 5 series aluminum alloy or 7 series aluminum alloy, the annealing temperature is 160° C.-280° C., and the holding time is 30 min-90 min.

[0042] In a preferred embodiment, when the material of the metal plate is 5 series aluminum alloy or 7 series aluminum alloy, in formula (1), X is 0.4-0.6, and Y is 0.2-0.3.

[0043] In a preferred solution, after the correction is completed, the metal sheet is directly unloaded from the correction device and placed in the air to cool to room temperature. No plastic deformation occurs during the entire correction process of the present invention, and finally the creep deformation and annealing softening coupling straightening of the metal sheet is achieved.

[0044] Beneficial effects:

[0045] 1. The orthopedic device provided by the present invention provides pressure through the upper push rod and directly applies it to the surface of the metal plate during loading, and the lower push rod A and the lower push rod B are supported at both ends of the metal plate. The metal plate bends under the pressure of the upper push rod, and the bending radius of the metal plate can be adjusted by adjusting the length of the screw screwed into the threaded hole to adjust the loading stress. During the orthopedic process, the above-mentioned orthopedic device and the metal plate can be placed in a heat treatment furnace to complete the orthopedic process and then taken out together, and then the length of the screw screwed into the threaded hole is adjusted and reduced until it reaches an appropriate position. At this time, the reset spring begins to reset and lift the upper push rod, and the upper push rod unloads the pressure on the metal plate, so that the metal plate can be restored to a straight state so as to be taken out from the mold, completing the reset and unloading process. The mold structure formed by the screw and the reset spring of the present invention allows workers to easily use manual drive to adjust the up and down movement of the upper pressure head during straightening, which is conducive to the straightening of thin plates with different deformation degrees and sizes, and has the advantages of convenient installation and disassembly and simple control operation;

[0046] 2. The present invention adopts a loading stress lower than the yield stress during the straightening process to avoid the introduction of residual stress caused by plastic deformation, so that only annealing softening and creep deformation exist during the straightening process. The applied thermal field can effectively reduce the residual stress of the thin plate material, and the short-term annealing softening and creep deformation treatment has little effect on the performance of the plate material, which is conducive to obtaining a thin plate material with high flatness and small residual stress. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 It is a schematic diagram of the overall structure of the straightening device of the present invention;

[0048] Figure 2 It is a schematic diagram of the overall structure of the straightening device of the present invention when loading a plate;

[0049] Figure 3 is the softening curve of 5A02 aluminum alloy rolled plate;

[0050] Figure 4 This is a metallographic photograph of 5A02 aluminum alloy rolled plate;

[0051] Figure 5 This is a metallographic photo of 5A02 aluminum alloy rolled plate after annealing at 240℃ for 4h:

[0052] Figure 6 It is a schematic diagram of the three stages of the creep process;

[0053] Figure 7 Schematic diagram of the calculation of the material's centrifugal distance;

[0054] Figure 8 It is a schematic diagram of three-point bending of a plate;

[0055] Fig. 9It is the softening curve of 7050 aluminum alloy rolled plate in O state;

[0056] Fig.10 This is a metallographic photograph of the O-state 7050 aluminum alloy rolled plate;

[0057] Fig.11 This is a metallographic photograph of O state 7050 aluminum alloy rolled plate after annealing at 280℃ for 4h.

[0058] The following are the descriptions of the reference numerals:

[0059] 1. Device body; 2. Lower push rod; 3. Fixing groove; 4. Upper pressure rod A or upper pressure rod B; 5. Through hole; 6. Straightening assembly; 7. Lower push rod fixing plate; 8. Threaded hole; 9. Bolt; 10. Gasket; 11. Reset spring; 12. Support assembly; 13. Aluminum alloy plate. DETAILED DESCRIPTION

[0060] like Figure 1 As shown, the present invention provides a corrective device for coupling creep forming and annealing softening of metal plates, the corrective device comprises a straightening component and a supporting component, the straightening component comprises a manual driving component and an upper pressure rod, the manual driving component comprises a bolt and a reset spring, the bolt consists of a head and a screw, the reset spring is sleeved on the lower end of the screw, the supporting component comprises a lower push rod A, a lower push rod B and a lower push rod fixing plate, a threaded hole is provided in the middle of the lower push rod fixing plate, the upper pressure rod and the lower push rod fixing plate are connected with the threaded hole through the screw, the upper pressure rod is provided with a through hole, through which the screw can pass and cooperate with the reset spring to realize the up and down movement of the upper push rod, the lower push rod fixing plate is also provided with a plurality of circular arc grooves, the circular arc grooves are all used to stabilize the lower push rod A and the lower push rod B, the lower push rod A and the lower push rod B are symmetrically arranged in any two circular arc grooves with the upper pressure rod as the center.

[0061] In a preferred implementation case, the lower push rod fixing plate is provided with two groups of threaded holes, any group of threaded holes contains two symmetrically distributed threaded holes, the connecting line of the two groups of threaded holes is vertical, and the upper pressure rod is provided with through holes corresponding to the two groups of threaded holes.

[0062] In a preferred embodiment, the arc grooves are distributed in both the transverse and longitudinal directions of the lower push rod fixing plate.

[0063] In a preferred embodiment, the bolt and the return spring are both symmetrically arranged. The return spring is arranged at two symmetrical positions, so that the user can manually rotate and adjust the pressing radius at different positions. At the same time, when the screw is unscrewed, the return spring pushes up the upper pressing rod to achieve reset.

[0064] In a preferred embodiment, the manual drive assembly further includes a gasket, which is arranged between the head of the bolt and the upper pressure rod.

[0065] In a preferred embodiment, the lower push rod A and the lower push rod B are cylinders of the same size. The lower push rod A and the lower push rod B of the same size are used to ensure that the force at both ends of the plate is evenly applied without deflection.

[0066] In a preferred embodiment, the radius of the through hole in the upper pressure rod is 1-1.5 mm larger than the outer diameter of the screw rod, so that each screw rod can be rotatably mounted on the lower push rod fixing plate.

[0067] In a preferred implementation case, the outer diameter of the lower push rod A and the lower push rod B is 1-3 mm larger than the inner diameter of the arc groove.

[0068] The following is a method for orthopedic treatment using the orthopedic device that couples creep forming and annealing softening of the above-mentioned metal sheet.

[0069] The method of the present invention realizes loading of the plate through the above-mentioned straightening device, and the radius of the downward pressing arc is adjusted according to the different initial deformation conditions of the plate, and loading is performed at a horizontal loading stress level lower than the yield stress; the plate and the straightening device are annealed together in a heat treatment furnace while maintaining the stress; after the insulation is completed, the plate is unloaded from the straightening device and placed in the air for cooling.

[0070] Example 1

[0071] First, the softening curve of 5A02 aluminum alloy rolled plate was measured to obtain the softening curve of 5A02 aluminum alloy rolled plate. Figure 3 As shown, Figure 3 It shows that annealing at 240℃ can effectively soften the plate, and the hardness can remain stable in a short time, and the hardness reduction within 1 hour does not exceed 5%. Figure 4 and Figure 5 It can be seen that annealing treatment at 240℃ for 4h has little effect on the grain morphology of 5A02 aluminum alloy rolled plate, so the annealing temperature was selected as 240℃.

[0072] Figure 6The figure shows the three stages of conventional creep aging treatment of aluminum alloy. The three stages are: the first stage is the high-speed creep stage, and when the first stage of creep (generally less than 1h for conventional aluminum alloy) is completed, 50%-80% of the total creep strain can be reached; the second stage is the steady-state creep stage, and the creep rate is infinitely close to 0; the third stage is the creep rupture stage, and the creep strain of the aluminum alloy increases sharply until it breaks. The creep deformation of aluminum alloy generally controls the processing time between the first stage of creep and the second stage of creep, so the holding time is set to 60min, which is enough to complete the creep deformation process of the aluminum alloy, and the creep strain is less than 1%.

[0073] Then, the initial deformation curvature of the 5A02 aluminum alloy rolled plate with a thickness of 0.7mm, a length of 380mm, and a width of 160mm was measured. The curvature radius of the initially deformed rolled plate was 3600mm. The X-ray diffraction measurement found that the residual stress on the plate surface was within ±25MPa. The tensile test was carried out at 240℃ with a constant strain rate of 0.01S-1, and the yield stress σ at this temperature was measured. s The elastic modulus is 115 MPa and 69 GPa. In order to ensure that the loaded stress is below the yield stress, the minimum curvature radius during the elastic bending of the sheet needs to be R min Analysis, to determine whether it is in elastic deformation relationship equation is:

[0074]

[0075] Where E is the elastic modulus of the material, t is the thickness of the plate, and R min is the yield limit of the material, so the minimum loading arc radius R min It is 115mm, that is, the radius of the pressing arc should be greater than this value.

[0076] Then calculate the radius R of the downward pressing arc:

[0077] The creep deformation stress of aluminum alloy generally does not exceed 60% of the yield stress, so the coefficient x is taken as 0.4, and considering the deformation caused by annealing softening, the coefficient Y is taken as 0.25. MAX =XYσ s , take the maximum bending normal stress to be less than 15% of the yield stress.

[0078] The equation for the bending normal stress is:

[0079]

[0080] Where σ is the bending stress, M is the bending moment acting on the material, y is the distance between the cross section and the farthest point of the material (also called the eccentricity of the material), and I is the moment of inertia of the cross section. The equation for the bending moment and the moment of inertia of the cross section is:

[0081]

[0082] Where R is the radius of the downward pressing arc, and the relationship equation between the bending normal stress and the curvature is:

[0083]

[0084] According to the elastic modulus of 69GPa, Figure 7 As shown, the vernier caliper measures the eccentric distance at the lower edge of the material to be 0.35mm, so the maximum downward pressing arc radius R is calculated to be 2100mm, and the downward pressing arc radius is set to 2100mm. According to the designed downward pressing arc radius, the initially deformed rolled plate is loaded onto the orthopedic device (the radius of the through hole in the upper pressing rod of the orthopedic device used is 1.0mm larger than the outer diameter of the screw, and the outer diameter of the lower push rod A and the lower push rod B is 2.0mm larger than the inner diameter of the arc groove), and is placed in a heat treatment furnace and heated with the furnace, and maintained for 1h after reaching the temperature.

[0085] After the insulation is completed, the straightening mold is taken out from the heat treatment furnace, and the unloading of the rectangular thin plate is completed within 5 minutes. The plate is left to stand in the air to cool to room temperature. Finally, the flatness of the rectangular thin plate after forming is measured by a height gauge to be 0.3mm. X-ray diffraction measurement shows that the residual stress on the plate surface is controlled within ±10MPa. The annealing treatment effectively reduces the residual stress of the plate. At the same time, annealing softening and creep forming straightening are achieved in a short time, which proves the feasibility of this method.

[0086] Example 2

[0087] First, the softening curve of the O-state 7050 aluminum alloy rolled plate was measured to obtain the softening curve of the O-state 7050 aluminum alloy rolled plate. Figure 3 As shown, Fig. 9 It shows that annealing at 280℃ can effectively soften the plate, and the hardness can remain stable in a short time, and the hardness reduction within 1 hour does not exceed 5%. Fig.10 and Fig.11 It can be seen that annealing at 280°C for 4 hours has little effect on the grain morphology of 7050 aluminum alloy rolled plate, so the annealing temperature was selected as 280°C. The holding time was set to 60 minutes, which is enough to complete the creep deformation process of the aluminum alloy, and the creep strain is less than 1%.

[0088] Then, the initial deformation curvature of the 7050 aluminum alloy rolled plate with a thickness of 1.2 mm, a length of 400 mm, and a width of 140 mm was measured. The curvature radius of the initially deformed rolled plate was 3150 mm. The X-ray diffraction measurement found that the residual stress on the plate surface was within ±27 MPa. The plate was subjected to a constant strain rate of 0.01 S at 280 °C. -1Conduct a tensile test and measure the yield stress σ at this temperature s The elastic modulus is 145 MPa and 72 GPa. In order to ensure that the loaded stress is below the yield stress, the minimum curvature radius during the elastic bending of the sheet metal needs to be R min Analysis, to determine whether it is in elastic deformation relationship equation is:

[0089]

[0090] Where E is the elastic modulus of the material, t is the thickness of the plate, and R min is the yield limit of the material, so the minimum loading arc radius R min It is 297mm, that is, the radius of the downward pressing arc should be greater than this value.

[0091] Then calculate the radius R of the downward pressing arc:

[0092] The creep deformation stress of aluminum alloy generally does not exceed 60% of the yield stress, and the coefficient x is taken as 0.6. Considering the deformation caused by annealing softening, the coefficient Y is taken as 0.25. According to σ MAX =XYσ s , take the maximum bending normal stress to be less than 15% of the yield stress.

[0093] The equation for the bending normal stress is:

[0094]

[0095] Where σ is the bending stress, M is the bending moment acting on the material, y is the distance between the cross section and the farthest point of the material (also called the eccentricity of the material), and I is the moment of inertia of the cross section. The equation for the bending moment and the moment of inertia of the cross section is:

[0096]

[0097] Where R is the radius of the downward pressing arc, and the relationship equation between the bending normal stress and the curvature is:

[0098]

[0099] According to the elastic modulus of 72GPa, Figure 7 As shown, the vernier caliper measures the eccentric distance at the lower edge of the material to be 0.6mm, so the maximum downward pressing arc radius R is taken as 1986mm, and the set downward pressing arc radius is 1986. According to the designed downward pressing arc radius, the initially deformed rolled plate is loaded onto the orthopedic device (the radius of the through hole in the upper pressing rod of the orthopedic device used is 1.5mm larger than the outer diameter of the screw, and the outer diameter of the lower push rod A and the lower push rod B is 2mm larger than the inner diameter of the arc groove), and is placed in a heat treatment furnace and heated with the furnace, and maintained for 1h after reaching the temperature.

[0100] After the insulation is completed, the straightening mold is taken out from the heat treatment furnace, and the rectangular thin plate is unloaded within 5 minutes. The plate is left to cool to room temperature in the air. Finally, the flatness of the rectangular thin plate after forming is measured by a height gauge to be 0.4mm. X-ray diffraction measurement shows that the residual stress on the plate surface is controlled within ±14MPa. The annealing treatment effectively reduces the residual stress of the plate. At the same time, annealing softening and creep forming straightening are achieved in a short time, which proves the feasibility of this method.

[0101] Comparative Example 1

[0102] Other conditions are the same as those in Example 1, except that the material is high carbon plastic steel Fe-18Mn-1.0C (%, mass fraction). After straightening, the flatness of the rectangular thin plate after forming was measured by a height gauge to be 1.7 mm. X-ray diffraction measurement found that the residual stress on the surface of the plate was controlled within ±27 MPa. Obviously, the high carbon plastic steel material is not suitable for the parameter setting within the scope of the present invention.

[0103] Comparative Example 2

[0104] Other conditions are the same as those in Example 1, except that the material thickness is 5 mm. After straightening, the flatness of the rectangular thin plate after forming is measured by a height gauge and is 2.2 mm. X-ray diffraction measurement shows that the residual stress on the plate surface is controlled within ±17 MPa. Obviously, when the plate thickness is greater than 5 mm, it is not suitable for the parameter setting within the scope of the present invention. This is because the greater the thickness of the plate, the more deformation is concentrated in the core of the plate during the bending process, and the edge of the plate basically remains a straight line. When the plate thickness is smaller (<2 mm), the bending forming contour is closer to an arc shape, which can effectively achieve uniform stress conduction and improve the straightening effect.

[0105] The standard parts used in this application document can all be purchased on the market, the connection method adopts the mature conventional bolt connection method, and the parts adopt the conventional models in the prior art, which will not be described in detail here. The embodiments of the present invention are given for the purpose of illustration and description, and are not intended to be exhaustive or limit the present invention to the disclosed form. Many modifications and changes are obvious to those of ordinary skill in the art. The embodiments are selected and described in order to better illustrate the principles and practical applications of the present invention, and to enable those of ordinary skill in the art to understand the present invention and design various embodiments with various modifications suitable for specific purposes.

Claims

1. A metal plate creep forming and annealing softening coupling orthopedic device, characterized in that: The orthopedic device includes a straightening component and a supporting component, the straightening component includes a manual drive component and an upper pressure rod, the manual drive component includes a bolt and a reset spring, the bolt consists of a head and a screw, the reset spring is sleeved on the lower end of the screw, the supporting component includes a lower push rod A, a lower push rod B and a lower push rod fixing plate, a threaded hole is provided in the middle of the lower push rod fixing plate, the upper pressure rod and the lower push rod fixing plate are connected to the threaded hole through the screw, the upper pressure rod is provided with a through hole, through which the screw can pass and cooperate with the reset spring to realize the up and down movement of the upper push rod, the lower push rod fixing plate is also provided with a plurality of circular arc grooves, the circular arc grooves are all used to stabilize the lower push rod A and the lower push rod B, the lower push rod A and the lower push rod B are arranged in any two circular arc grooves symmetrical with the upper pressure rod as the center.

2. The orthopedic device of the metal sheet coupled with creep forming and annealing softening according to claim 1, characterized in that: The lower push rod fixing plate is provided with two groups of threaded holes, any group of threaded holes contains two symmetrically distributed threaded holes, the connecting line of the two groups of threaded holes is vertical, and the upper pressure rod is provided with through holes corresponding to the two groups of threaded holes.

3. A metal sheet creep forming and annealing softening coupling orthopedic device according to claim 1 or 2, characterized in that: The arc grooves are distributed in the transverse and longitudinal directions of the lower push rod fixing plate; The bolts and the return springs are both symmetrically arranged in pairs.

4. A metal sheet creep forming and annealing softening coupling orthopedic device according to claim 1 or 2, characterized in that: The manual drive assembly further comprises a gasket, which is arranged between the head of the bolt and the upper pressure rod.

5. A metal sheet creep forming and annealing softening coupling orthopedic device according to claim 1 or 2, characterized in that: The lower push rod A and the lower push rod B are cylinders with the same size.

6. A metal sheet creep forming and annealing softening coupling orthopedic device according to claim 1 or 2, characterized in that: The radius of the through hole in the upper pressure rod is 1-1.5 mm larger than the outer diameter of the screw rod; the outer diameter of the lower push rod A and the lower push rod B is 1-3 mm larger than the inner diameter of the circular arc groove.

7. A method for correcting a metal sheet by coupling creep forming and annealing softening, using the device according to any one of claims 1 to 6, characterized in that: A sample of the same material as the metal sheet to be corrected is used to measure the softening curve of the sample annealed at different temperatures, and the temperature and time at which the hardness reduction ratio does not exceed 5% and the metallographic structure before and after the softening treatment remains stable are selected as the annealing temperature and the holding time. Then, after the required downward pressing arc radius R is obtained by calculation, the metal sheet to be corrected is loaded onto the corrective device so that it is located above the lower push rod A and the lower push rod B and below the upper push rod. During loading, the position of the lower push rod is adjusted by bolts according to the downward pressing arc radius R, and the corrective device loaded with the metal sheet to be corrected is placed in a heat treatment furnace. Annealing softening and creep deformation are simultaneously performed at the above annealing temperature and holding time for correction, and the correction is immediately cooled after the correction is completed; The calculation method of the downward pressing arc radius R is: First, based on the relationship between the creep deformation stress and the yield stress of the metal sheet to be corrected, and the deformation caused by softening under annealing, the bending normal stress is set according to formula (1); σ≤XYσ s Where Y is 0.1-0.5 Formula (1) Where X is the coefficient of the relationship between the creep deformation stress and the yield stress of the metal sheet to be corrected, and Y is the coefficient based on the deformation caused by annealing softening; Then, according to the relationship between bending normal stress and curvature, R is calculated according to formula (2): Wherein E is the elastic modulus of the metal sheet to be corrected, and y is the eccentric distance of the metal sheet to be corrected.

8. The metal sheet creep forming and annealing softening coupling correction method according to claim 7 is characterized by: Samples of the same material as the metal sheet to be corrected are used to measure the softening curves of the samples annealed at different temperatures and the creep aging treatment curves. The temperature and time when the hardness reduction ratio does not exceed 5%, the metallographic structure before and after softening treatment remains stable, and the creep strain is less than 1% are selected as the annealing temperature and holding time.

9. The metal sheet creep forming and annealing softening coupling correction method according to claim 7, characterized in that: The material of the metal plate is 5 series aluminum alloy or 7 series aluminum alloy, the thickness of the metal plate is 0.3-2 mm, and the shape of the plate is rectangular; When the material of the metal sheet is 5 series aluminum alloy or 7 series aluminum alloy, the annealing temperature is 160°C-280°C, and the holding time is 30min-90min; When the material of the metal plate is 5 series aluminum alloy or 7 series aluminum alloy, in formula (1), X is 0.4-0.6, and Y is 0.2-0.

3.

10. The metal sheet creep forming and annealing softening coupling correction method according to claim 7, characterized in that: After the orthosis is completed, the metal sheet is directly unloaded from the orthosis device and placed in the air to cool to room temperature.

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