CN115090751B - Method for improving shot blasting forming limit of ribbed integral wallboard - Google Patents
Method for improving shot blasting forming limit of ribbed integral wallboard Download PDFInfo
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- CN115090751B CN115090751B CN202210827872.XA CN202210827872A CN115090751B CN 115090751 B CN115090751 B CN 115090751B CN 202210827872 A CN202210827872 A CN 202210827872A CN 115090751 B CN115090751 B CN 115090751B
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- 238000005422 blasting Methods 0.000 title claims abstract description 83
- 238000000034 method Methods 0.000 title claims abstract description 54
- 238000005452 bending Methods 0.000 claims abstract description 86
- 238000005259 measurement Methods 0.000 claims abstract description 8
- 238000005480 shot peening Methods 0.000 claims description 21
- 239000000463 material Substances 0.000 claims description 17
- 230000007935 neutral effect Effects 0.000 claims description 13
- 238000012360 testing method Methods 0.000 claims description 13
- 230000005489 elastic deformation Effects 0.000 claims description 5
- 230000005483 Hooke's law Effects 0.000 claims description 4
- 238000007493 shaping process Methods 0.000 claims 2
- 238000004364 calculation method Methods 0.000 description 6
- 238000013461 design Methods 0.000 description 5
- 238000005516 engineering process Methods 0.000 description 5
- 230000003631 expected effect Effects 0.000 description 3
- 229910001250 2024 aluminium alloy Inorganic materials 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000006467 substitution reaction Methods 0.000 description 2
- 238000004891 communication Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 230000002427 irreversible effect Effects 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- JTJMJGYZQZDUJJ-UHFFFAOYSA-N phencyclidine Chemical compound C1CCCCN1C1(C=2C=CC=CC=2)CCCCC1 JTJMJGYZQZDUJJ-UHFFFAOYSA-N 0.000 description 1
- 239000002760 rocket fuel Substances 0.000 description 1
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D31/00—Other methods for working sheet metal, metal tubes, metal profiles
- B21D31/06—Deforming sheet metal, tubes or profiles by sequential impacts, e.g. hammering, beating, peen forming
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
- B21C51/00—Measuring, gauging, indicating, counting, or marking devices specially adapted for use in the production or manipulation of material in accordance with subclasses B21B - B21F
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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Abstract
The invention discloses a method for improving shot blasting forming limit of a ribbed integral wallboard, which comprises the following steps: determining the elastic pre-bending radius of the integral wall plate with the ribs; bending the ribbed integral wallboard by using a shot blasting forming tool; performing preliminary shot blasting forming on the outer surface of the integral wallboard with the ribs; residual stress measurement is carried out on the center position of the sprayed surface to obtain a residual stress value sigma m; calculating a re-pre-bending radius value, and re-pre-bending the ribbed integral wallboard; shot blasting forming is carried out on the outer surface of the integral wallboard with the ribs again; unloading the formed ribbed integral wallboard from the shot blasting forming tool after forming; and (5) carrying out curvature measurement on the appearance of the formed integral wall plate with the ribs. The invention greatly improves the deformation capacity of shot blasting forming, and leads the surface of the integral wallboard with the rib to obtain larger residual compressive stress, thereby improving the fatigue life of the integral wallboard with the rib.
Description
Technical Field
The invention relates to the technical field of shot blasting forming, in particular to a method for improving the shot blasting forming limit of a ribbed integral wallboard.
Background
The large integral ribbed wallboard is one of the most important main bearing structures of aviation equipment, and the level of manufacturing technology directly influences indexes such as equipment performance. The shot-blasting forming technology is the most important manufacturing method of the metal wing wallboard of the current large-scale aircraft, and the principle is that the high-speed shot flow is utilized to impact the surface of the metal plate, so that the impacted surface and the underlying metal material are plastically deformed and extended, and the plate is gradually bent to reach the target shape. Because the special mould and press are not needed in the forming process, the forming method is flexible and various, and the fatigue performance of the parts can be improved, so that the method is very suitable for large-sized parts, and is widely applied to the forming of the integral wall plates of wings, fuselages, carrier rocket fuel tanks and the like of an airplane.
Along with the technical development of shot-peening, the pre-stress shot-peening is gradually promoted, and the pre-stress shot-peening is a method for pre-applying elastic deformation load on a part plate blank by means of a pre-stress clamp before shot-peening, ensuring that the part does not enter plasticity and is easy to generate defects, and then performing shot-peening on the part. The forming limit of the prestressed shot blasting can reach 2-3 times of that of the free shot blasting under the same shot blasting energy and coverage rate.
Along with the improvement of the mobility, durability and fuel economy requirements of the novel advanced aircraft, the whole ribbed wallboard structure is more and more complex, the curvature radius of the wallboard surface is greatly reduced, and the forming difficulty is increased. Under the constraint of high rigidity of the ribbed wallboard, the conventional shot blasting forming process has a deformation limit, and if the limit cannot meet the requirements of certain local curved surfaces of theoretical digital-analog parts of the parts, the shot blasting forming process cannot be applied to the structure, so that the appearance design of the parts is limited, and the overall performance of the aircraft is influenced.
In the whole ribbed wallboard shot blasting forming process, the forming curvature can be improved by the implementation of prestress, the existing mode is that the part is elastically pre-bent through a tool, the pre-bending amount in the pre-bending process is required to be always smaller than the material yield critical point, otherwise, the part is extremely easy to cause defects such as cracks or rib instability, and the part is scrapped. And carrying out shot blasting forming on the part under the conditions of limiting pre-bending and limiting shot blasting parameters, wherein the appearance curvature of the obtained part is the forming limit of the part structure. The size of the forming limit directly affects the part number-die design range, thereby affecting the pneumatic profile design of the part in the complete machine. Aiming at the problems that the high-strength thin-wall wallboard is large in elastic pre-bending radius and low in forming curvature, the local area cannot meet the design requirement of the novel advanced aircraft aerodynamic shape, the application of the process is seriously influenced, and the development of the aircraft aerodynamic design is limited.
Aiming at the problems, how to provide a new method for improving the shot blasting forming limit for the integral wall plate with the rib to improve the forming curvature radius of the wall plate with the rib, thereby expanding the application range of the forming process and solving the technical problem which is needed to be solved by the person skilled in the art.
Disclosure of Invention
(1) Technical problem to be solved
The embodiment of the invention provides a method for improving the shot blasting forming limit of a ribbed integral wallboard, which comprises the following steps: determining the elastic pre-bending radius of the integral wall plate with the ribs; bending the ribbed integral wallboard; performing preliminary shot blasting forming; and (3) performing pre-bending again, performing shot blasting forming on the outer surface of the integral wall plate with the ribs again, and the like. The invention greatly improves the deformation capacity of shot blasting forming, and leads the surface of the integral wallboard with the rib to obtain larger residual compressive stress, thereby improving the fatigue life of the integral wallboard with the rib.
(2) Technical proposal
The embodiment of the invention discloses a method for improving the shot blasting forming limit of a ribbed integral wallboard, which comprises the following steps:
step one: determining the elastic pre-bending radius of the integral wall plate with the ribs;
step two: bending the ribbed integral wallboard by using a shot blasting forming tool;
step three: performing preliminary shot blasting forming on the outer surface of the integral wallboard with the ribs;
step four: unloading the ribbed integral wallboard, and measuring residual stress at the center of the sprayed surface to obtain a residual stress value sigma m;
step five: calculating the re-preflex radius value R according to the formula (1) σ And according to the value R of the re-preflex radius σ And (3) pre-bending the ribbed integral wallboard again by using a shot blasting forming tool:
wherein K is a constant, and the yield strength of the sigma s ribbed integral wallboard material is taken within the range of 0.9-0.98;
step six: shot blasting forming is carried out on the outer surface of the integral wallboard with the ribs again;
step seven: unloading the formed ribbed integral wallboard from the shot blasting forming tool after forming;
step eight: and (5) carrying out curvature measurement on the appearance of the formed integral wall plate with the ribs.
Further, the method for determining the elastic pre-bending radius comprises the following steps:
firstly, determining a neutral layer of the ribbed integral wallboard according to the section geometry of the ribbed integral wallboard;
secondly, according to Hooke's law, the tangential stress at the radial distance y from the centroid on the section where the neutral layer is located is obtained asWherein R is the curvature radius of the neutral layer, ey is the elastic modulus of the material;
then, assuming that the material is subjected to only tangential stress, the elastic deformation condition is | (σ) θ )|≤σ s ，σ s For yield strength, minimum bending radius at the elastic limit state
The minimum bend radius is the elastic pre-bend radius.
Further, in the second step, the actual bending radius of the shot-peening tool for bending the ribbed integral wall plate should be smaller than the elastic pre-bending radius of the ribbed integral wall plate determined in the first step.
Further, the shot blast air pressure value of the preliminary shot blast forming in the third step is determined by a shot blast forming pit diameter test.
Further, the maximum value of the shot blasting air pressure when the pit meets the requirement is determined according to the shot blasting pit diameter test, and the shot blasting is performed according to the maximum value of the shot blasting air pressure during preliminary shot blasting.
Further, the shot coverage rate is changed by adjusting the moving speed of the integral wall plate with the ribs during preliminary shot blasting forming, and the shot coverage rate range is 30% -40%.
Further, in the fourth step, the residual stress is measured by an X-ray method.
And step five, after the ribbed integral wall plate is pre-bent again, measuring the surface residual stress of the ribbed integral wall plate, and verifying whether the surface residual stress is compressive stress.
Further, the shot blasting air pressure is 0.1-0.5MPa when the outer surface of the ribbed integral wallboard is subjected to shot blasting forming, and the shot blasting coverage range is 95% -98%.
Further, after the step eight operation, if the profile curvature of the shaped ribbed integral wallboard does not reach the elastic pre-bending radius determined in the step one, the operations of the step four to the step eight should be performed again until the profile curvature of the shaped ribbed integral wallboard reaches the elastic pre-bending radius determined in the step one.
(3) Advantageous effects
According to the embodiment of the invention, the elastic pre-bending radius of the ribbed integral wallboard is determined through theoretical calculation, so that the elastic pre-bending radius cannot exceed the theoretical elastic pre-bending radius in the pre-bending process. And then the preflex operation is carried out within the theoretical elastic preflex radius range, so that the integral wall plate with the ribs is ensured not to generate plastic deformation. And then measuring the residual stress value of the ribbed integral wallboard. And calculating the re-preflex radius value according to the obtained residual stress value and the corresponding calculation formula. Finally, the outer surface of the ribbed integral wallboard is shot-blasted again with knowledge of the pre-bend radius value. Aiming at the forming requirement of the ribbed wallboard, the embodiment of the invention provides a method for improving the shot blasting forming limit, which greatly improves the shot blasting forming deformation capacity of the ribbed integral wallboard part and expands the application range of the forming technology; compared with the traditional forming method, the method can lead the surface of the ribbed integral wallboard part to obtain larger residual compressive stress, thereby prolonging the fatigue life of the ribbed integral wallboard part.
Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments of the present invention will be briefly described below, and it is obvious that the drawings described below are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort to a person of ordinary skill in the art.
FIG. 1 is a flow chart of a method of increasing the shot forming limits of a ribbed monolithic panel according to one embodiment of the invention.
Fig. 2 is a photograph of a rib integral panel obtained according to an embodiment of the present invention after shot peening.
Detailed Description
Embodiments of the present invention are described in further detail below with reference to the accompanying drawings and examples. The following detailed description of the embodiments and the accompanying drawings are provided to illustrate the principles of the invention and are not intended to limit the scope of the invention, i.e., the invention is not limited to the embodiments described, but covers any modifications, substitutions and improvements in parts, components and connections without departing from the spirit of the invention.
It should be noted that, in the case of no conflict, the embodiments and features in the embodiments may be combined with each other.
The present application will be described in detail with reference to fig. 1-2 in conjunction with the embodiments.
Referring to fig. 1, a method for improving shot peening forming limit of a ribbed integral wallboard according to an embodiment of the present invention includes the following steps:
step one: determining the elastic pre-bending radius of the integral wall plate with the ribs;
step two: bending the ribbed integral wallboard by using a shot blasting forming tool;
step three: performing preliminary shot blasting forming on the outer surface of the integral wallboard with the ribs;
step four: unloading the ribbed integral wallboard, and measuring residual stress at the center of the sprayed surface to obtain a residual stress value sigma m;
step five: calculating the re-preflex radius value R according to the formula (1) σ And according to the value R of the re-preflex radius σ And (3) pre-bending the ribbed integral wallboard again by using a shot blasting forming tool:
wherein K is a constant, and the yield strength of the sigma s ribbed integral wallboard material is taken within the range of 0.9-0.98;
step six: shot blasting forming is carried out on the outer surface of the integral wallboard with the ribs again;
step seven: unloading the formed ribbed integral wallboard from the shot blasting forming tool after forming;
step eight: and (5) carrying out curvature measurement on the appearance of the formed integral wall plate with the ribs.
In the embodiment of the invention, firstly, the elastic pre-bending radius of the ribbed integral wall plate is determined through theoretical calculation, so that a theoretical limit value is provided for the shot-blasting forming limit of the ribbed integral wall plate, and the fact that the theoretical elastic pre-bending radius is not exceeded in the pre-bending process is ensured.
And then the rib-provided integral wall plate is subjected to the first-stage pre-bending, and when the rib-provided integral wall plate is subjected to the first-stage pre-bending, the actual bending radius is smaller than the elastic pre-bending radius of the rib-provided integral wall plate determined in the first step, so that a certain margin can be provided for the pre-bending in the subsequent step, and the condition that the rib-provided integral wall plate is damaged due to the one-time pre-bending is avoided. Therefore, the actual bending radius should be less than the elastic pre-bending radius of the ribbed integral panel determined in step one.
Next, the outer surface of the integral wallboard with the ribs is subjected to preliminary shot blasting forming, and the pre-stress shot blasting can improve the forming limit of the shot blasting and effectively control the direction along the shot blasting routeThe additional bending deformation of the complex shape curvature part is solved. And unloading the ribbed integral wallboard after the preliminary shot blasting forming is finished at the stage, and measuring residual stress at the center of the sprayed surface to obtain a residual stress value sigma m. By measuring the residual stress value, it can be understood how much of the second preflex needs to be experienced by the ribbed integral panel from the intended elastic preflex radius after the first preflex. Specifically, in the fifth step of the embodiment of the present invention, the residual stress value σm is obtained. And equation (1) calculate the re-preflex radius value R σ And according to the value R of the re-preflex radius σ And (3) pre-bending the ribbed integral wallboard again by using a shot blasting forming tool:
wherein K is a constant, and the yield strength of the sigma s ribbed integral wallboard material is taken within the range of 0.9-0.98; by the residual stress value sigma m. And the formula (1) can accurately calculate the value R of the re-preflex radius σ So that the re-preflex radius can be known clearly and quantitatively. Therefore, the embodiment of the invention innovatively provides a formula for calculating the pre-bending amount by combining the residual stress value sigma m, and specific quantitative parameters are provided for improving the shot forming limit.
Finally, knowing the pre-bend radius value R σ Then, the shot blasting forming tool is utilized to perform pre-bending on the reinforced integral wallboard according to the corresponding pre-bending radius number, and then shot blasting forming is performed on the outer surface of the reinforced integral wallboard again; and unloading the formed ribbed integral wallboard from the shot blasting forming tool after forming.
In addition, the embodiment of the invention carries out curvature measurement on the appearance of the integrally ribbed wallboard after forming, and judges whether the shot blasting forming of the integrally ribbed wallboard achieves the expected effect or not according to the curvature measurement. If the expected effect is not achieved, the steps can be carried out again until the shot blasting forming of the integral wall plate with the ribs achieves the expected effect.
In summary, in the embodiment of the invention, the elastic pre-bending radius of the integral wall plate with the rib is determined through theoretical calculation, so that the elastic pre-bending radius cannot exceed the theoretical elastic pre-bending radius in the pre-bending process. And then the preflex operation is carried out within the theoretical elastic preflex radius range, so that the integral wall plate with the ribs is ensured not to generate plastic deformation. And then measuring the residual stress value of the ribbed integral wallboard. And calculating the re-preflex radius value according to the obtained residual stress value and the corresponding calculation formula. Finally, the outer surface of the ribbed integral wallboard is shot-blasted again with knowledge of the pre-bend radius value. Aiming at the forming requirement of the ribbed wallboard, the embodiment of the invention provides a method for improving the shot blasting forming limit, which greatly improves the shot blasting forming deformation capacity of the ribbed integral wallboard part and expands the application range of the forming technology; compared with the traditional forming method, the method can lead the surface of the ribbed integral wallboard part to obtain larger residual compressive stress, thereby prolonging the fatigue life of the ribbed integral wallboard part.
Specifically, according to one embodiment of the present invention, the method for determining the elastic pre-bending radius includes:
firstly, determining a neutral layer of the ribbed integral wallboard according to the section geometry of the ribbed integral wallboard;
secondly, according to Hooke's law, the tangential stress at the radial distance y from the centroid on the section where the neutral layer is located is obtained asWherein R is the curvature radius of the neutral layer, ey is the elastic modulus of the material;
then, assuming that the material is subjected to only tangential stress, the elastic deformation condition is | (σ) θ )|≤σ s ，σ s For yield strength, minimum bending radius at the elastic limit state
The minimum bend radius is the elastic pre-bend radius.
In the embodiment of the invention, the theory about the elastic bending of the plate in the material mechanics is known that when the shear stress does not exceed the elastic limit of the material, the Hooke's law is applied to obtainThe shear stress at radial distance y from the centroid (neutral layer position) on the cross section isWherein R is the curvature radius of the neutral layer, and E is the elastic modulus of the material. In order to simplify the model, in the embodiment of the invention, assuming that the material is subjected to only tangential stress, the elastic deformation condition is | (σ) θ )|≤σ s ，σ s Is the yield strength. Therefore, the minimum bending radius +.>The minimum bending radius at this time is the elastic pre-bending radius, so that the theoretical elastic pre-bending radius of the integral wall plate with the ribs can be conveniently calculated.
Specifically, according to another embodiment of the present invention, in the second step, the actual bending radius of the reinforced integral wall panel by the shot forming tool should be smaller than the elastic pre-bending radius of the reinforced integral wall panel determined in the first step. The method is characterized in that the elastic pre-bending radius of the integral wall plate with the rib is determined through theoretical calculation, so that the elastic pre-bending radius cannot be exceeded in the pre-bending process; if the actual bending radius of the bead-forming tool for bending the reinforced integral wall plate in the second step exceeds the elastic pre-bending radius of the reinforced integral wall plate determined in the first step, permanent irreversible damage can occur to the reinforced integral wall plate, so that the actual bending radius of the bead-forming tool for bending the reinforced integral wall plate should be smaller than the elastic pre-bending radius of the reinforced integral wall plate determined in the first step.
Specifically, according to another embodiment of the present invention, the shot blast air pressure value of the preliminary shot blast in the third step is determined by a shot blast pit diameter test. After the shot blast air pressure value of the preliminary shot blast forming is determined by the shot blast forming pit diameter test, the shot blast forming equipment can be set to a predetermined shot blast air pressure value to perform the preliminary shot blast forming on the outer surface of the integral panel with the rib.
Specifically, according to one embodiment of the invention, the maximum value of the shot blast air pressure when the pit meets the requirement is determined according to the shot blast forming pit diameter test, and the shot blast is performed according to the maximum value of the shot blast air pressure during the preliminary shot blast forming. After the maximum value of the shot blast air pressure value of the preliminary shot blast forming is determined through the shot blast forming pit diameter test, the shot blast forming equipment can be set to the maximum value of the preset shot blast air pressure value to perform the preliminary shot blast forming on the outer surface of the integral wall plate with the rib, and the preliminary shot blast forming is performed according to the maximum value of the shot blast air pressure, so that the optimal shot blast effect can be achieved.
Further, according to still another embodiment of the present invention, the shot coverage is changed by adjusting the moving speed of the ribbed integral panel at the time of preliminary shot forming, and the shot coverage ranges from 30% to 40%.
Specifically, according to another embodiment of the present invention, the residual stress measurement in the fourth step employs an X-ray method.
Specifically, according to an embodiment of the present invention, after the rib-formed integral wall plate is pre-bent again, the surface residual stress of the rib-formed integral wall plate is measured, and whether the surface residual stress is compressive stress is verified, so that the surface residual stress value of the rib-formed integral wall plate after the rib-formed integral wall plate is pre-bent again can be accurately known, and further, the pre-bending parameters can be adjusted again according to the magnitude of the surface residual stress value of the rib-formed integral wall plate, and the shot-peening forming deformation capacity and the forming limit of the rib-formed integral wall plate can be greatly improved.
Specifically, according to still another embodiment of the present invention, the peening air pressure at the time of peening the outer surface of the ribbed integral wallboard in the step six is 0.1-0.5MPa, and the peening coverage ratio is in the range of 95% -98%.
Specifically, after the step eight operation, if the profile curvature of the shaped ribbed integral panel is found to not reach the elastic pre-bending radius determined in the step one, the step four-step eight operation should be performed again until the profile curvature of the shaped ribbed integral panel reaches the elastic pre-bending radius determined in the step one. Therefore, the formed ribbed integral wallboard can be checked again to ensure that the preset elastic pre-bending radius is achieved.
The following is a specific example of a method for improving the shot peening limit of a ribbed integral panel according to an embodiment of the present invention.
Referring to fig. 1, a forming test is performed on a 2024 aluminum alloy ribbed part by using the method for improving the shot forming limit of the ribbed integral wallboard according to the embodiment of the present invention, and the test steps and data are as follows:
(1) Geometric analysis: determining a neutral layer of the ribbed integral wallboard according to the geometric dimension of the section of the ribbed integral wallboard, and combining the elastic modulus E and the yield strength sigma s=383 MPa of the ribbed integral wallboard material to obtain an elastic pre-bending radius R of 6043mm;
(2) Applying elastic pre-bending: bending the ribbed integral wallboard by using a shot-blasting forming tool, and measuring the curvature of the outer surface of the ribbed integral wallboard, wherein the actual bending radius Rr=R/95% =6361 mm is maintained;
(3) Preliminary shot blasting forming: determining the maximum value P=0.5 MPa of the shot blasting air pressure when the shot pit meets the standard requirement according to a shot blasting forming pit diameter test, performing preliminary shot blasting forming on the outer surface of the part by setting the parameter P=0.5 MPa of shot blasting forming equipment, and changing the shot blasting coverage rate by adjusting the moving speed of the integral wall plate with the ribs so that the coverage rate eta=35%;
(4) Participate in stress test analysis: unloading the ribbed integral wallboard, and measuring residual stress at the center of the sprayed surface by using an X-ray method to obtain sigma m & lt- & gt & lt 155MPa ("-" represents compressive stress);
(5) Residual stress method pre-bending: obtaining a re-preflex radius value Rsigma according to the following formula, and re-preflex the ribbed integral wallboard:wherein k=0.95;
(6) Overlapped shot blasting forming: performing overlapped shot blasting forming on the outer surface of the ribbed integral wallboard by setting shot blasting forming parameters of shot blasting forming equipment to have the shot blasting air pressure P=0.5 MPa, and changing the shot blasting coverage rate by adjusting the moving speed of the ribbed integral wallboard so that the coverage rate eta=96%;
(7) Unloading parts: unloading the ribbed integral wallboard from the shot blasting forming tool after the shot blasting forming is finished;
(8) Appearance detection: and measuring the appearance curvature of the ribbed integral wallboard part after shot blasting forming by using a clamping plate or an arc height meter.
Finally, referring to fig. 2, by using the method for improving the shot peening limit of the integral wallboard with the rib, disclosed by the embodiment of the invention, a forming test is performed on a certain 2024 aluminum alloy ribbed part, wherein the minimum curvature radius is 6.8m, and compared with the curvature radius obtained by traditional shot peening, the curvature radius is reduced by 36.4%, so that the bending deformation capability is greatly improved. Therefore, the embodiment of the invention provides a method for improving the shot blasting forming limit aiming at the forming requirement of the ribbed wallboard, so that the shot blasting forming deformation capacity of the ribbed integral wallboard part is greatly improved, and the application range of the forming technology is expanded; compared with the traditional forming method, the method can lead the surface of the ribbed integral wallboard part to obtain larger residual compressive stress, thereby prolonging the fatigue life of the ribbed integral wallboard part.
In the description of the present invention, unless explicitly stated and limited otherwise, the terms "mounted," "connected," and "coupled" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; may be a mechanical or electrical connection; may be directly connected, indirectly connected through intervening media, or in communication between two elements. The specific meaning of the above terms in the present invention will be understood in specific cases by those of ordinary skill in the art.
In the description of the present specification, reference to the terms "embodiment," "specific embodiment," "example," and the like, means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention, or may be combined in a suitable manner, and schematic representations of the terms described above do not necessarily refer to the same embodiment or example.
While embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that: many changes, modifications, substitutions and variations may be made to the embodiments without departing from the spirit and principles of the invention, the scope of which is defined by the claims and their equivalents.
Claims (10)
1. A method for improving shot peening forming limit of a ribbed integral wallboard, comprising the steps of:
step one: determining the elastic pre-bending radius of the integral wall plate with the ribs;
step two: bending the ribbed integral wallboard by using a shot blasting forming tool;
step three: performing preliminary shot blasting forming on the outer surface of the integral wallboard with the ribs;
step four: unloading the ribbed integral wallboard, and measuring residual stress at the center of the sprayed surface to obtain a residual stress value sigma m ；
Step five: calculating the re-preflex radius value R according to the formula (1) σ And according to the value R of the re-preflex radius σ And (3) pre-bending the ribbed integral wallboard again by using a shot blasting forming tool:
wherein K is a constant, and is 0.9-0.98, sigma s Yield strength, R of ribbed integral wallboard material r Is the actual bending radius;
step six: shot blasting forming is carried out on the outer surface of the integral wallboard with the ribs again;
step seven: unloading the formed ribbed integral wallboard from the shot blasting forming tool after forming;
step eight: and (5) carrying out curvature measurement on the appearance of the formed integral wall plate with the ribs.
2. The method for improving the shot peening forming limit of a ribbed integral panel according to claim 1, wherein said method for determining the elastic pre-bending radius comprises:
firstly, determining a neutral layer of the ribbed integral wallboard according to the section geometry of the ribbed integral wallboard;
secondly, according to Hooke's law, the radial distance from the centroid of the section where the neutral layer is located can be obtained
The shear stress at y isWherein R is the curvature radius of the neutral layer, ey is the elastic modulus of the material, and y is the radial distance from the centroid on the section where the neutral layer is positioned;
then, assuming that the material is subjected to only tangential stress, the elastic deformation condition is | (σ) θ )|≤σ s ，σ s For yield strength, minimum bending radius at the elastic limit state
The minimum bend radius is the elastic pre-bend radius.
3. The method of claim 1, wherein in the second step, the actual bending radius of the reinforced integral panel by the shot forming tool is smaller than the elastic pre-bending radius of the reinforced integral panel determined in the first step.
4. The method for improving the shot forming limit of a ribbed panel according to claim 1, wherein the shot air pressure value of the preliminary shot forming in the third step is determined by a shot forming pit diameter test.
5. The method for improving the shot forming limit of the ribbed integral panel according to claim 4, wherein the maximum value of the shot blast pressure when the pit meets the requirement is determined according to the shot forming pit diameter test, and the shot blast is performed according to the maximum value of the shot blast pressure during the preliminary shot forming.
6. The method for improving the shot forming limit of the ribbed integral panel according to claim 4, wherein the shot coverage is changed by adjusting the moving speed of the ribbed integral panel during the preliminary shot forming, and the shot coverage is in the range of 30% -40%.
7. The method for improving the shot peening limit of a ribbed integral panel according to claim 1, wherein in the fourth step, the residual stress is measured by an X-ray method.
8. The method for improving the shot peening limit of a ribbed integral panel according to claim 1, wherein after the ribbed integral panel is pre-bent again, the surface residual stress of the ribbed integral panel is measured to verify whether the surface residual stress is compressive stress.
9. The method for improving the shot peening limit of a ribbed integral panel according to claim 5, wherein the shot peening air pressure in the shot peening of the outer surface of the ribbed integral panel in the step six is 0.1-0.5MPa, and the shot peening coverage ratio is 95% -98%.
10. The method for improving the shot peening limit of the ribbed integral panel according to claim 1, wherein after the step eight operation, if the curvature of the profile of the ribbed integral panel after the shaping is found to be less than the elastic pre-bending radius determined in the step one, the step four-step eight operation is performed until the curvature of the profile of the ribbed integral panel after the shaping is found to be more than the elastic pre-bending radius determined in the step one.
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