A method for locating and eliminating forging defects

Abstract

The present invention discloses a method for locating and eliminating forging defects, which relates to the field of forging process technology. The method comprises the following steps: S1. obtaining a three-dimensional model of a preforging, performing a forging simulation on the three-dimensional model of the preforging, and obtaining defect areas and defect types on the forging after the preforging is simulated and formed. The defect types include metal accumulation and metal folding; S2. performing reverse tracing based on the defect areas using a finite element analysis method to obtain areas of the preforging to be optimized; and S3. adjusting the shape and size of the preforging based on the defect type and the location of the area to be optimized to obtain an optimized preforging. The method for locating and eliminating forging defects provided by the present invention is conducive to reducing workload and improving work efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of forging technology, and in particular to a method for locating and eliminating defects in forgings. Background Art

[0002] Modern aircraft wheels are large, complex forgings characterized by deep cavities, sudden cross-sections, high ribs, and thin walls. These components are prone to defects such as localized metal accumulation and folding during forming. For a long time, eliminating these localized defects in wheel forgings relied primarily on the theoretical knowledge and experience of designers, requiring on-site mold trials and modifications. This resulted in low mold design efficiency, poor precision, high production costs, and long development cycles.

[0003] Pages 37-45 of "Study on Precision Forging Forming Process and Microstructure of Differential Axle Flange" (Shandong University, Sun Weiyan, April 25, 2019) disclose a forging process design method that combines numerical simulation and experiment. The precision forging process of the axle flange was studied. In order to avoid forging defects, the shape of the preform was optimized, and the quality of the forging was improved to a certain extent. Its main design method is to use numerical simulation to simulate the metal flow law during the preforging forming process, obtain the difficulty of deformation of each part of the forging and the cause and type of defects of the forging, further redistribute the volume occupied by the corresponding parts of the preforging, and design four preforging modification schemes. Then, the preforging forming process is simulated by finite element simulation software, and the defect-free preforging is selected from them. This method fails to accurately obtain the position of the preforging corresponding to the defect area of ​​the forging. Its idea of ​​adjusting the shape and size of the preforging is basically the same as the traditional trial and error method, which is somewhat blind and has a large workload. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for locating and eliminating forging defects to solve the problems existing in the above-mentioned prior art, which is conducive to reducing workload and improving work efficiency.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] The present invention provides a method for locating and eliminating forging defects, which is characterized by comprising:

[0007] S1. Obtain a three-dimensional model of a pre-forging, perform a forging simulation on the three-dimensional model of the pre-forging and obtain defect areas and defect types on the forging after the pre-forging simulation, the defect types including metal accumulation and metal folding;

[0008] S2. Reverse tracking is performed using a finite element analysis method according to the defect area to obtain the area to be optimized for the pre-forging;

[0009] S3. Adjust the shape and size of the pre-forging according to the defect type and the position of the area to be optimized to obtain an optimized pre-forging.

[0010] Preferably, S1 includes: obtaining an initial shape and initial size of a first cross-section of the three-dimensional model of the pre-forging, wherein a plane on which the first cross-section is located passes through the axis of the pre-forging; obtaining a second cross-section of the forging, wherein the second cross-section is coplanar with the first cross-section, and a portion of the defect region on the second cross-section is a first defect region;

[0011] S2 includes: performing reverse tracing based on the first defective area using a finite element analysis method to obtain a first area to be optimized on the first cross section of the pre-forged part;

[0012] S3 includes: adjusting the initial shape and the initial size of the first cross-section according to the defect type and the position of the first area to be optimized to obtain a first optimized cross-section, and obtaining the shape and size of the optimized pre-forging through the shape and size of the first optimized cross-section, and any cross-section of the optimized pre-forging passing through its own axis is the same as the first optimized cross-section.

[0013] Preferably, S2 includes: selecting multiple reverse points on the first defect area, tracing the multiple reverse points back to the first section, the point where each reverse point is traced back to the first section is the original point, and determining the area where the original point is located as the first area to be optimized.

[0014] Preferably, S2 includes: selecting multiple reverse points on the contour of the first defect area, reversely tracing the multiple reverse points on the contour of the first defect area to the first section, obtaining multiple original points, and determining the area surrounded by the multiple original points as the first area to be optimized.

[0015] Preferably, S2 includes: uniformly selecting a plurality of the inversion points on the contour of the first defect area.

[0016] Preferably, S3 includes: a portion of the contour of the first cross-section corresponding to the first area to be optimized is a contour to be optimized, and the initial shape and initial size of the first cross-section can be adjusted by adjusting the contour to be optimized.

[0017] Preferably, S3 includes: the method for adjusting the contour to be optimized is to move at least one adjustment point on the contour to be optimized in a direction that can reduce the volume of the pre-forging.

[0018] Preferably, S3 further includes: the adjustment principle of the profile to be optimized is to select the adjustment scheme that has the smallest volume change of the pre-forging after adjustment relative to the pre-forging before adjustment among the available adjustment schemes.

[0019] Preferably, S1 includes: numerically simulating the forging process of the pre-forged part by using Deform software; S2 includes: performing reverse tracking by using Deform software;

[0020] The method for locating and eliminating forging defects provided by the present invention further includes S4: performing numerical simulation of the forging process on the three-dimensional model of the optimized pre-forging to verify whether the defects of the optimized pre-forging are eliminated.

[0021] Preferably, the pre-forging is a wheel hub pre-forging.

[0022] Compared with the prior art, the present invention has achieved the following technical effects:

[0023] The method for locating and eliminating forging defects provided by the present invention can obtain the defect type and defect area by simulating the forging process, and obtain the area to be optimized on the pre-forging according to the defect area using a reverse tracing method. The area to be optimized on the pre-forging can be accurately found, and the shape and size of the pre-forging can be adjusted according to the defect type and the position of the area to be optimized, which is conducive to reducing workload and improving work efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0025] Figure 1 A flow chart of the method for locating and eliminating forging defects provided by the present invention;

[0026] Figure 2 A cross-sectional view of a pre-forging and a die in the method for locating and eliminating forging defects provided in Example 1;

[0027] Figure 3 A schematic diagram of a forging and a reversal point in the method for locating and eliminating forging defects provided in Example 1;

[0028] Figure 4 A schematic diagram of a pre-forged part and an original point in the method for locating and eliminating forging defects provided in Example 1;

[0029] Figure 5 A schematic diagram of α in the method for locating and eliminating forging defects provided in Example 1;

[0030] Figure 6The fitting lines of the eight original points in the method for locating and eliminating forging defects provided in Example 1;

[0031] Figure 7 A schematic structural diagram of the optimized preform in the method for locating and eliminating forging defects provided in Example 1;

[0032] Figure 8 This is a schematic diagram of forging simulation of the optimized preform in the forging defect location and elimination method provided in Example 1;

[0033] In the figure: 1, pre-forging; 2, die; 3, first cross section; 4, second cross section; 5, through hole. DETAILED DESCRIPTION

[0034] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0035] The purpose of the present invention is to provide a method for locating and eliminating forging defects to solve the problems existing in the above-mentioned prior art, which is conducive to reducing workload and improving work efficiency.

[0036] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0037] like Figure 1-8 As shown, the present invention provides a method for locating and eliminating forging defects, comprising:

[0038] S1. Obtain a three-dimensional model of a pre-forging, perform a forging simulation on the three-dimensional model of the pre-forging and obtain defect areas and defect types on the forging after the pre-forging simulation, the defect types including metal accumulation and metal folding;

[0039] S2. Reverse tracking is performed using a finite element analysis method according to the defect area to obtain the area to be optimized for the pre-forging;

[0040] S3. Adjust the shape and size of the pre-forging according to the defect type and the position of the area to be optimized to obtain an optimized pre-forging.

[0041] The method for locating and eliminating forging defects provided by the present invention can obtain the defect type and defect area by simulating the forging process, and obtain the area to be optimized on the pre-forging according to the defect area using a reverse tracing method. The area to be optimized on the pre-forging can be accurately found, and the shape and size of the pre-forging can be adjusted according to the defect type and the position of the area to be optimized, which is conducive to reducing workload and improving work efficiency.

[0042] In an optional scheme of the present invention, the pre-forging is an axisymmetric part, that is, the present invention can be used to locate and eliminate defects in axisymmetric forgings. In this type of forging defect location and elimination method, S1 includes: obtaining a first cross-section of the three-dimensional model of the pre-forging, the plane where the first cross-section is located passes through the axis of the pre-forging, and obtaining the initial shape and initial size of the first cross-section; obtaining a second cross-section of the forging, the second cross-section is coplanar with the first cross-section, and the part of the defect area on the second cross-section is the first defect area.

[0043] In a further optional solution, the preforging has a through hole in the middle. The axial cross-section of such a preforging includes two cross-sections located on both sides of the axis of the preforging, and these two cross-sections constitute the first cross-section. Since these two cross-sections are two identical cross-sections and symmetrical about the axis of the preforging, only one of the cross-sections can be analyzed during the simulation analysis. The judgment of defect areas and defect types based on the forging simulation process is a prior art, and can be judged by referring to the method disclosed on pages 37-45 of "Research on Precision Forging Forming Process and Microstructure of Differential Axle Flange" (Shandong University, Sun Weiyan, April 25, 2019).

[0044] S2 includes: using the finite element analysis method to perform reverse tracing based on the first defect area to obtain the first area to be optimized of the pre-forging on the first cross section; it should be noted that the defect area of ​​the forging obtained during the forging simulation is three-dimensional, and it is considered that the generation of defects is uniform, that is, the position and shape of the defect area on any axial cross section of the forging are exactly the same as the position and shape of the first defect area on the obtained second cross section. Similarly, the position and shape of the area to be optimized on any axial cross section of the pre-forging are exactly the same as the position and shape of the first area to be optimized on the obtained first cross section; the corresponding area to be optimized on the three-dimensional model of the pre-forging is three-dimensional, and the part of the area to be optimized on the first cross section is the first area to be optimized.

[0045] S3 includes: adjusting the initial shape and initial size of the first cross-section according to the defect type and the position of the first area to be optimized to obtain a first optimized cross-section, and obtaining the shape and size of the optimized pre-forging based on the shape and size of the first optimized cross-section, wherein any cross-section of the optimized pre-forging passing through its axis is identical to the first optimized cross-section. A three-dimensional model of the optimized pre-forging can be obtained using three-dimensional modeling software based on the first optimized cross-section.

[0046] In a preferred embodiment, S2 includes: selecting multiple reverse points on the first defect area, tracing the multiple reverse points back to the first cross section, and the point where each reverse point is traced back to the first cross section is the original point, and the area where the original point is located is determined as the first area to be optimized. It should be noted that the reverse points need to be able to roughly characterize the shape of the first defect area, and multiple reverse points cannot be concentrated in a local area of ​​the first defect area, which will result in a lower accuracy of the obtained first area to be optimized. Preferably, multiple reverse points are evenly selected in the defect area of ​​the second cross section to improve the accuracy of the position of the first area to be optimized.

[0047] In another preferred embodiment, S2 includes: selecting a plurality of the reverse points on the contour of the first defect area, reversely tracing the plurality of reverse points on the contour of the first defect area to the first cross section, obtaining a plurality of the original points, and determining the area surrounded by the plurality of the original points as the first area to be optimized. Selecting a plurality of the reverse points on the contour of the first defect area can confirm the position and approximate shape of the first area to be optimized with fewer reverse points, which is conducive to reducing workload and improving design efficiency. It should be noted that the reverse points need to be able to roughly characterize the contour shape of the first defect area, and the plurality of reverse points cannot be concentrated at the local position of the contour of the first defect area, which will result in lower accuracy of the obtained first area to be optimized.

[0048] As a preferred embodiment, S2 includes: uniformly selecting multiple reversal points on the contour of the first defect area, which is conducive to further improving the accuracy of positioning the first area to be optimized. It should be noted that the selection of reversal points is not limited to the above-mentioned uniform selection. In order to simplify the design process, reversal points can be selected on the main contour segment of the first defect area contour. For example, the part of the contour of the first defect area that coincides with the outer contour of the forging (the part of the forging close to the inner wall of the forging die during the forging process) is the first contour segment, and the part of the contour of the first defect area that is opposite to the first contour segment is the second contour segment. Multiple reversal points are selected on both the first contour segment and the second contour segment. When performing forging simulation, the flow direction of the metal is roughly directed to the inner wall of the die, so reversal points are selected on the first contour segment and the second contour segment, which is equivalent to selecting reversal points in the area corresponding to the main position where the defect first appears and the main position where the defect ends (the stop position of the metal flow). The original points corresponding to these reversal points can better determine the shape of the first area to be optimized and further shorten the time required for analysis.

[0049] As a preferred embodiment, S3 includes: a portion of the contour of the first cross-section corresponding to the first area to be optimized is the contour to be optimized, and the initial shape and initial size of the first cross-section can be adjusted by adjusting the contour to be optimized.

[0050] As a preferred embodiment, S3 includes: the method for adjusting the contour to be optimized is to move at least one adjustment point on the contour to be optimized in a direction that can reduce the volume of the pre-forging. According to existing design experience, when metal accumulation or metal folding defects occur in the forging, it is necessary to partially cut off the corresponding position of the pre-forging, so it is necessary to move at least one adjustment point on the contour to be optimized in a direction close to the middle position of the mold to adjust the shape and position of the contour to be optimized (or the contour to be optimized and the contour segment of the first section connected to the contour to be optimized); which points on the contour to be optimized are moved and how much they are moved can be determined based on the designer's existing design experience with pre-forgings.

[0051] As a preferred embodiment, S3 further includes: the adjustment principle of the adjustment point is to select the adjustment solution that minimizes the volume change of the pre-forging after adjustment relative to the pre-forging before adjustment, among the available adjustment solutions, that is, to minimize the volume change of the pre-forging before and after adjustment.

[0052] As a preferred embodiment, S1 includes: numerically simulating the forging process of the pre-forged part by using Deform software; and S2 includes: performing reverse tracking by using Deform software.

[0053] As a preferred embodiment, the method for locating and eliminating forging defects provided by the present invention further includes S4: performing a numerical simulation of the forging process on the three-dimensional model of the optimized pre-forging to verify whether the optimized pre-forging has eliminated defects. If defects still occur after verification, further optimization is performed according to the above method until a pre-forging that meets the requirements is obtained.

[0054] Example 1

[0055] The pre-forged part is a wheel hub pre-forged part, and the first cross section is parallel to the axial cross section of the wheel hub pre-forged part.

[0056] Take wheel hub forgings as an example for analysis, specifically:

[0057] 1. Obtain the initial shape and size of the first cross section of the pre-forged part according to the design requirements of the wheel hub: Select multiple feature points that can characterize the first cross section profile of the pre-forged part, and Figure 2 It can be seen that the first cross-sectional profile of the pre-forging is composed of several straight lines, an arc segment and a similar straight line. Among them, the arc segment selects its own two endpoints S2 and S4 and a point S3 in the middle of the two endpoints as feature points. The similar straight line selects its own two endpoints S7 and S8 as feature points. The remaining multiple straight lines all select their respective two endpoints as feature points, specifically S1 and S8, S4 and S5, S5 and S6, S6 and S7, S7 and S2. The horizontal coordinates of S6 and S7 are the same, the vertical coordinates of S6 and S5 are the same, and the vertical coordinates of S1 and S3 are the same. According to the existing design experience of pre-forgings, specifically according to the positioning of the forgings and the convenience of forging, the contour segments S7S8 are fitted with the inner wall of the mold, and the contour segments S4S5 are fitted with the inner wall of the mold. The coordinates of S7 and S8 are preset to be fixed during design, that is, the positions of S7 and S8 are not adjusted during adjustment. The horizontal coordinate x1 of S1, the horizontal coordinate x2 of S2, the vertical coordinate y3 of S4, the vertical coordinate y5 of S5, and the angle θ between the straight line S1S2 and the horizontal coordinate are preset as design variables, that is, these design variables are preferably adjusted during adjustment.

[0058] 2. Obtain a three-dimensional model of the pre-forged part and perform a forging simulation. After the forging simulation, it was found that the forging part had metal stacking defects. Reverse points P1, P2, P3, and P4 were selected on the first contour segment, and reverse points P5, P6, P7, and P8 were selected on the second contour segment. After reverse tracing, the original points P1, P2, P3, P4, P5, P6, P7, and P8 were obtained on the pre-forged part. The original points P1, P2, P3, P4, P5, P6, P7, and P8 represent the position and approximate shape of the first area to be optimized, where the position of the first area to be optimized is located on the arc segment. The coordinates of P1, P2, P3, P4, P5, P6, P7, and P8 before and after forging are shown in Table 1:

[0059] Table 1 Coordinate values ​​of tracking points before and after reverse tracking

[0060]

[0061] Among them, the original point P2 coincides with the feature point S3.

[0062] 3. Adjust the shape and size of the first cross-section of the pre-forged part. The design variable x2 can be adjusted to remove excess material. It should be noted that the adjustment method is not limited to adjusting the design variable x2. Based on existing design experience, some material can be removed from the first area to be optimized, as long as the volume change of the pre-forged part before and after the adjustment is as small as possible.

[0063] Preferably, the adjustment of x2(S2) can be achieved by adjusting the angle α, where:

[0064] tanα=-Δy / Δx=-k (1-1)

[0065] α=tan -1 (-Δy / Δx) = tan -1 (-k) (1-2)

[0066] Where:

[0067] α——the angle between the original point fitting line and the horizontal direction. The original point fitting curve is a straight line obtained by linearly fitting the eight original points using the least squares method;

[0068] Δy——the difference between the ordinates of any two points on the original point fitting line;

[0069] Δx——the difference between the horizontal coordinates of any two points on the original point fitting line;

[0070] k is the slope of the line obtained by the least squares linear fit.

[0071] Linear fitting of these eight original points can obtain the fitting line and the slope of the fitting curve. Since the original point P2 coincides with the feature point S3, we can use S3 as the starting point and the slope of the fitting line as the slope to draw a ray and extend it to the line where s1 and s3 are located to complete the cutting. Using formula (1-2) to simulate the data in Table 1, we get α = 74°, and the fitting curve is as follows Figure 6 As shown, the feature point s3 is selected as the endpoint of the ray and the direction with an angle of -74° with the horizontal is used to cut the pre-forged piece, which is equivalent to adjusting x1 and x2 to obtain Figure 7 The cross section of the pre-forged part is shown. It should be noted that this adjustment method is only an example of adjustment, and other methods can also be used to adjust and eliminate defects.

[0072] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A method for locating and eliminating forging defects, characterized by: include: S1. Obtain a three-dimensional model of a pre-forging, perform a forging simulation on the three-dimensional model of the pre-forging and obtain defect areas and defect types on the forging after the pre-forging simulation, the defect types including metal accumulation and metal folding; Obtaining an initial shape and initial size of a first cross-section of the three-dimensional model of the pre-forging, wherein a plane where the first cross-section is located passes through an axis of the pre-forging; obtaining a second cross-section of the forging, wherein the second cross-section is coplanar with the first cross-section, and a portion of the defective region on the second cross-section is a first defective region; S2. performing reverse tracing based on the defective area using a finite element analysis method to obtain an area of ​​the pre-forging to be optimized; performing reverse tracing based on the first defective area using a finite element analysis method to obtain a first area of ​​the pre-forging to be optimized on the first cross section; S3. Adjust the shape and size of the pre-forging according to the defect type and the position of the area to be optimized to obtain an optimized pre-forging; adjust the initial shape and the initial size of the first section according to the defect type and the position of the first area to be optimized to obtain a first optimized section, and obtain the shape and size of the optimized pre-forging through the shape and size of the first optimized section.

2. The method for locating and eliminating forging defects according to claim 1, characterized in that: The pre-forging is an axisymmetric part, and the pre-forging is a wheel hub pre-forging; S3 includes: any cross section of the optimized pre-forging passing through its own axis is the same as the first optimized cross section.

3. The method for locating and eliminating forging defects according to claim 2, characterized in that: S2 includes: selecting multiple reverse points on the first defect area, tracing the multiple reverse points back to the first section, the point on the first section to which each reverse point is traced back is the original point, and determining the area where the original point is located as the first area to be optimized.

4. The method for locating and eliminating forging defects according to claim 3, wherein: S2 includes: selecting multiple reverse points on the contour of the first defect area, reversely tracing the multiple reverse points on the contour of the first defect area to the first section, obtaining multiple original points, and determining the area surrounded by the multiple original points as the first area to be optimized.

5. The method for locating and eliminating forging defects according to claim 4, characterized in that: S2 includes: A plurality of the inversion points are uniformly selected on the contour of the first defect area.

6. The method for locating and eliminating forging defects according to claim 4, characterized in that: S3 includes: a portion of the contour of the first cross-section corresponding to the first area to be optimized is a contour to be optimized, and an initial shape and an initial size of the first cross-section can be adjusted by adjusting the contour to be optimized.

7. The method for locating and eliminating forging defects according to claim 6, characterized in that: S3 includes: the method for adjusting the contour to be optimized is to move at least one adjustment point on the contour to be optimized in a direction that can reduce the volume of the pre-forging.

8. The method for locating and eliminating forging defects according to claim 6, characterized in that: S3 further includes: the adjustment principle of the profile to be optimized is to select the adjustment scheme that has the smallest volume change of the pre-forging after adjustment relative to the pre-forging before adjustment among the available adjustment schemes.

9. The method for locating and eliminating forging defects according to claim 1, characterized in that: S1 includes: Numerical simulation of the forging process of the pre-forged part is performed using Deform software; S2 includes: reverse tracking via Deform software; The method further includes S4: performing a numerical simulation of the forging process on the three-dimensional model of the optimized pre-forged part to verify whether defects of the optimized pre-forged part are eliminated.

10. The method for locating and eliminating forging defects according to claim 1, wherein: The pre-forging is a wheel hub pre-forging.

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