Blade preform and method for designing a profile thereof

Abstract

The application discloses a kind of blade preform and its profile design method, belong to machining technical field, from the section of preform profile design selects A0 section and N section, form a set of theoretical profile in several sections from A0 section to N section for preform design;Connecting theoretical profile leading edge circle center and trailing edge circle, at every n equal parts of X axial distance L, the tangent circle of upper and lower curves of theoretical profile is made with equal division line as circle center, and the middle camber line of theoretical profile is produced by spline line sequentially connecting all tangent circle circle centers from leading edge circle center;With the intersection point of X axial distance L midline and the middle camber line as circle center, make the tangent circle of theoretical profile, and make the tangent circle of theoretical profile on both sides of X axial distance L midline;According to the deformation of blade forming, obtain closed preform profile.The application is used for the design of blade part preform, by reasonably distributing metal volume, the deformation degree of blade finish forging is consistent, and more uniform structure is obtained.

Description

Technical Field

[0001] This invention belongs to the field of machining technology, specifically relating to a blade pre-forging part and its profile design method. Background Technology

[0002] For blades with wide chords, thin walls, and large curvature, the under-pressure method or the elliptical method is usually used in the pre-forging process. The under-pressure method uses the theoretical profile of the blade to offset in the direction of thickness increase. The offset amount is calculated by multiplying the dimension of the thickest part of the theoretical profile by the required degree of deformation. The elliptical method is similar to the under-pressure method. The minor axis of the ellipse is calculated by multiplying the thickest part of the theoretical profile by the required degree of deformation. The structure can be one ellipse or two connected ellipses with a curve transition.

[0003] The above methods have the following drawbacks: the pre-forging profile of the pre-forging part designed by the under-pressure method is completely aligned with the theoretical profile, resulting in large metal flow resistance, large dimensional deformation, and short die life during forming; the pre-forging profile designed by the elliptical method has large differences in the degree of deformation of each part, which affects the uniformity of grains. During the deformation process, the metal bends first and then forms, resulting in large residual stress. The blades are prone to metallurgical defects such as longitudinal bright and dark stripes and cracks.

[0004] In summary, the existing pre-forging profile design methods for pre-forging parts have the problem of causing large dimensional deformation and high residual stress in the pre-forging parts. Summary of the Invention

[0005] The purpose of this invention is to provide a blade pre-forging and its profile design method, which is used for the design of blade pre-forgings. By rationally allocating the metal volume, the deformation degree of the blade during final forging is consistent, resulting in a more uniform microstructure.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for designing the profile of a blade pre-forging includes the following steps:

[0008] Step 1: Select section A0 and section N from the cross sections of the pre-forging profile design, and select intermediate sections between section A0 and section N according to a preset distance to form a set of theoretical profiles from section A0 to section N for pre-forging design;

[0009] Step 2: Connect the center of the leading edge circle and the trailing edge circle of the theoretical profile. At each n equal division of the distance L along the X-axis, draw the tangent circles of the upper and lower curves of the theoretical profile with the dividing line as the center. Use splines to sequentially connect all the centers of the tangent circles starting from the center of the leading edge circle to produce the middle arc line of the theoretical profile.

[0010] Step 3: Using the intersection of the midline of the X-axis distance L and the arc line of Step 2 as the center, draw the tangent circle of the theoretical profile in Step 1, and draw the tangent circles of the theoretical profile on both sides of the midline of the X-axis distance L.

[0011] Step 4: Based on the deformation of the blade forming, expand the diameter of the three circles in Step 3 to obtain three new circles. Draw arcs tangent to the upper and lower halves of each of the three new circles to obtain an upper and lower arc, denoted as arc R. 上 Arc R 下 ;

[0012] Step 5, based on arc R 上 Arc R 下 Together with the new circles at both ends in step 4, a closed pre-forging profile is obtained;

[0013] Step 6: Repeat steps 2 to 5 to complete the theoretical profile operation of the remaining section selected in step 1, and obtain a set of closed pre-forging profiles.

[0014] Preferably, in step 1, the distance from section A0 to section N is S; the intermediate section is the data calculated from A0 for every additional S / m. The sections closest to each other on both sides of this data are selected to form a set of m+1 theoretical profiles from section A0 to section N for pre-forging design.

[0015] Furthermore, in step 1, m is selected from the range of 2, 3, 4, 5, and 6.

[0016] Preferably, in step 2, n is selected as an integer not less than 9.

[0017] Preferably, in step 3, the tangent circle in step 2 is removed, and the theoretical profile in step 1 and the middle arc in step 2 are retained. A tangent circle of the theoretical profile is drawn with the intersection of the centerline and the middle arc at a distance L along the X-axis as the center, and the diameter is ΦT0. Tangent circles of the theoretical profile are drawn at positions offset L / 3 to the left and right of the centerline, with diameters ΦT1 and ΦT2, respectively.

[0018] Preferably, in step 4, the deformation range of the blade forming is between 20% and 80%.

[0019] Furthermore, when the blade is made of TC4 titanium alloy, the deformation during blade forming is 50%.

[0020] Preferably, in step 5, the new circle at the leading edge is moved from the arc R... 上 Arc R 下 At the tangent point, break the arc on the left and retain it, denoted as R1. Then, connect the new circle at the rear edge to the arc R. 上 Arc R 下 At the tangent point, the arc on the right is broken and retained, denoted as R2. Thus, the arc R1 and the curve R... 上 Circular arc R2, Arc R 下 This forms a closed pre-forged profile.

[0021] Preferably, in step 6, a three-dimensional model of the subsequent pre-forging is performed based on a set of closed pre-forging profiles.

[0022] A blade pre-forging part is provided, wherein a set of closed pre-forging part profiles is obtained by adopting any one of the blade pre-forging part profile design methods described above for subsequent three-dimensional modeling of the pre-forging part; based on the three-dimensional modeling of the pre-forging part, a mold for the pre-forging part is machined by a CNC machine tool, and the mold is used to forge the pre-forging part.

[0023] Compared with the prior art, the present invention has the following beneficial technical effects:

[0024] This invention provides a method for designing the profile of a blade pre-forging. By dividing the overall blade profile into several control sections, and calculating the offset at three points (two sides and the middle) for each control section, a new model is created. This avoids the problems associated with under-pressure design methods and elliptical methods used in existing technologies. By rationally allocating the metal volume, this invention ensures consistent deformation during final forging, resulting in a more uniform microstructure. When the pre-forging designed using this method is placed in the final forging die, only the middle area of ​​the pre-forging contacts the die, while large areas at the leading and trailing edges are far from the die. This mitigates temperature loss caused by heat transfer between the pre-forging and the die, maintaining a higher initial forging temperature. Furthermore, the volume distribution and curvature direction of the pre-forging facilitate metal flow. This design method achieves better dimensional accuracy, surface quality, and a more uniform microstructure. Attached Figure Description

[0025] Figure 1 A schematic diagram is selected for the theoretical profile;

[0026] Figure 2 This is a schematic diagram for calculating the arc.

[0027] Figure 3 A schematic diagram for calculating the closed curve;

[0028] Figure 4 This is a cross-sectional view of the pre-forged part in the final forging die. Detailed Implementation

[0029] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of the invention. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0030] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0031] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0032] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0033] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0034] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0035] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0036] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0037] The accompanying drawings illustrate various structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0038] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0039] The present invention provides a method for designing the profile of a blade pre-forging, comprising the following steps:

[0040] Step 1: Select section A0 and section N from the cross sections of the pre-forging profile design, and select intermediate sections between section A0 and section N according to the preset distance to form a set of theoretical profiles from section A0 to section N for pre-forging design.

[0041] Step 2: Connect the center of the leading edge circle and the trailing edge circle of the theoretical profile. At each n equal division of the distance L along the X-axis, draw the tangent circles of the upper and lower curves of the theoretical profile with the dividing line as the center. Use splines to sequentially connect all the tangent circle centers starting from the center of the leading edge circle to produce the middle arc line of the theoretical profile.

[0042] Step 3: Using the intersection of the midline of the X-axis distance L and the arc line of Step 2 as the center, draw the tangent circle of the theoretical profile in Step 1, and draw the tangent circles of the theoretical profile on both sides of the midline of the X-axis distance L.

[0043] Step 4: Based on the deformation of the blade forming, expand the diameter of the three circles in Step 3 to obtain three new circles. Draw arcs tangent to the upper and lower halves of each of the three new circles to obtain an upper and lower arc, denoted as arc R. 上 Arc R 下 .

[0044] Step 5, based on arc R 上Arc R 下 Together with the new circles at both ends in step 4, we obtain a closed pre-forging profile.

[0045] Step 6: Repeat steps 2 to 5 to complete the theoretical profile operation of the remaining cross-section selected in step 1, obtaining a set of closed pre-forging profiles. Based on the obtained set of closed pre-forging profiles, perform 3D modeling of the pre-forging. After 3D modeling, a physical mold can be machined using CNC machine tools through 3D software programming. This mold is then used to produce pre-forgings that meet the requirements of deformation degree and reasonable metal distribution.

[0046] This invention provides a method for designing the profile of a blade pre-forging. By dividing the overall blade profile into several control sections, and calculating the offset at two points on each side and the middle of each control section, the model is re-built. This avoids the problems of large metal flow resistance and significant dimensional deformation caused by the under-pressure design method used in existing technologies, which uses a distance equal to the thickness of the thickest part of the blade multiplied by the deformation amount, resulting in a certain overall offset between the top and bottom surfaces. It also avoids the problems of large differences in deformation degree between different parts of the elliptical pre-forging profile, affecting grain uniformity, and the metal bending before forming during deformation, leading to high residual stress and metallurgical defects such as longitudinal bright and dark stripes and cracks on the blade. This invention achieves a more uniform microstructure by rationally distributing the metal volume, ensuring consistent deformation degree during final forging. The blade is thickest in the middle, followed by the leading edge, and thinnest at the trailing edge. When the pre-forged part designed using this method is placed in the final forging die, only the middle area of ​​the pre-forged part is in contact with the die, while the large areas of the leading and trailing edges are far away from the die. On the one hand, this reduces the temperature loss caused by heat transfer between the pre-forged part and the die, maintaining a high initial forging temperature. On the other hand, the volume distribution and curvature direction of the pre-forged part are conducive to metal flow. This design method can achieve better dimensional accuracy, surface quality, and uniform microstructure.

[0047] Example 1

[0048] This invention provides a method for designing the profile of a blade pre-forging, which is a method for designing blade-like parts from the final theoretical profile to the pre-forging profile, achieving a reasonable volume distribution and uniform deformation of the pre-forging; this method is achieved through the following steps:

[0049] (1) Selection of theoretical profile: The final blade body is controlled by a set of theoretical profiles from section A0 to section N, with a distance of S between sections A0 and N. The sections used for the pre-forging profile design are first selected from section A0 and section N. The intermediate section is the data calculated from A0 for each position increasing by S / m (m can be 2, 3, 4, 5, or 6). The section closest to this data is selected, thus selecting a set of m+1 theoretical profiles from section A0 to section N for the pre-forging design.

[0050] (2) Calculate the middle arc: Connect the center of the front edge circle and the rear edge circle of the theoretical profile. With a distance of L in the X-axis, draw the tangent circles of the upper and lower curves of the theoretical profile at each n equal division of distance L with the dividing line as the center (n≥9). Use spline to connect all the centers of the tangent circles in sequence from the center of the front edge circle to produce the middle arc of the theoretical profile.

[0051] (3) Define control points: Delete the auxiliary tangent circle, keep the theoretical profile and the middle arc line. With the intersection of the middle line and the middle arc line of L as the center, draw the tangent circle of the theoretical profile with a diameter of ΦT0. Perform the above operation at the position of L / 3 offset to the left and right of the middle line, with diameters of ΦT1 and ΦT2 respectively.

[0052] (4) Generating the cross-sectional line: The deformation amount of the blade forming is X% (generally between 20% and 80% depending on the material properties). The diameters of the three circles are increased by 1 / (1-X%) times while keeping their centers unchanged to obtain new enlarged circles. Arcs are drawn tangent to the upper and lower halves of these new circles, resulting in two arcs, denoted as R. 上 、R below.

[0053] (5) Generate a closed line: Connect the new circle at the leading edge to R. 上 R 下 At the tangent point, break the arc on the left side and keep it as R1. Then, connect the new circle at the trailing edge to R. 上 R 下 At the tangent point, the arc on the right side is broken and retained, denoted as R2. Thus, the arcs R1 and R2 are... 上 R2, R 下 This forms a closed pre-forged profile.

[0054] (6) Repeat steps (2) to (5) to complete the theoretical profile operation of the remaining section selected in (1) to obtain a set of closed pre-forging profiles for later three-dimensional modeling of pre-forgings.

[0055] Example 2

[0056] Taking the stage 0 stator blade of a certain engine as an example, the specific steps include:

[0057] (1) Selection of theoretical profile: The final blade body is controlled by a set of theoretical profiles from section A0 to section A24, with a distance of 109.2 mm between sections A0 and A24. The sections used for the pre-forging profile design are first selected from sections A0 and A24. The intermediate section is the data calculated from A0, where the position increases by S / 4 = 27.3 mm (m is taken as 4). The section closest to this data is selected, thus selecting a set of 4+1 theoretical profiles (sections A0, A3, A6, A12, and A24) for the pre-forging design.

[0058] (2) Calculate the middle arc: Connect the center of the front edge circle and the rear edge circle of the theoretical profile. With a distance of L along the X-axis, draw the tangent circles (n=16) of the upper and lower curves of the theoretical profile at each 16-part interval of distance L, with the dividing line as the center. Use splines to connect all the centers of the tangent circles in sequence from the center of the front edge circle to generate the middle arc of the theoretical profile.

[0059] (3) Define control points: Delete the auxiliary tangent circle, keep the theoretical profile and the middle arc line. With the intersection of the center line of L and the middle arc line as the center, draw the tangent circle of the theoretical profile with a diameter of Φ4.55mm. The center line of L / 2 is offset to the front edge and the rear edge direction by L / 3 to intersect the middle arc line. Then perform the above operation to obtain the front and rear edge diameters of Φ3.03mm and Φ2.57mm respectively.

[0060] (4) Generating the cross-sectional line: The blade is made of TC4 titanium alloy, and the required final forging deformation of the blade body is 50% (generally between 20% and 80% depending on the material properties). The diameter of the three circles is increased by 1 / (1-50%) = 2 times while keeping the center unchanged to obtain a new enlarged circle. Arcs are drawn tangent to the upper and lower halves of the three circles (Φ3.03mm, Φ4.55mm, and Φ2.57mm) respectively, resulting in two arcs, denoted as R. 上 、R below.

[0061] (5) Generate a closed line: Connect the new circle at the leading edge to R. 上 R 下 At the tangent point, break the arc on the left side and keep it as R1. Then, connect the new circle at the trailing edge to R. 上 R 下 At the tangent point, the arc on the right side is broken and retained, denoted as R2. Thus, the arcs R1 and R2 are... 上 R2, R 下 This forms a closed pre-forged profile.

[0062] (6) Repeat steps (2) to (5) to complete the theoretical profile operation of the remaining section selected in (1) to obtain a set of closed pre-forging profiles for later three-dimensional modeling of pre-forgings.

[0063] This invention provides a blade pre-forging part. Using the aforementioned blade pre-forging part profile design method, a set of closed pre-forging part profiles is obtained for subsequent 3D modeling of the pre-forging part. Based on the 3D model of the pre-forging part, a CNC machine tool is used to machine the upper and lower dies for the final forging of the pre-forging part. The pre-forging part designed using this method is placed into the final forging die. The forging part in the original state of the die is shown below. Figure 4 The pre-forged part only fits the middle area of ​​the mold, while the front and rear edges are far away from the mold. On the one hand, this reduces the temperature loss caused by heat transfer between the pre-forged part and the mold, maintaining a high initial forging temperature. On the other hand, the volume distribution and curvature direction of the pre-forged part are conducive to the flow of metal. This design method can achieve better dimensional accuracy, surface quality and uniform structure.

[0064] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the scope of the invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0065] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that can be understood by those skilled in the art. The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A method for designing the profile of a blade pre-forging, characterized in that, Includes the following steps, Step 1: Select section A0 and section N from the cross sections of the pre-forging profile design, and select intermediate sections between section A0 and section N according to a preset distance to form a set of theoretical profiles from section A0 to section N for pre-forging design; Step 2: Connect the center of the leading edge circle and the center of the trailing edge circle of the theoretical profile. With a distance of L along the X-axis, at each n equal division of the distance L along the X-axis, draw tangent circles for the upper and lower curves of the theoretical profile with the points on the dividing lines as the centers. Use splines to sequentially connect all the centers of the tangent circles starting from the center of the leading edge circle to produce the middle arc line of the theoretical profile; n is selected as an integer not less than 9. Step 3: Using the intersection of the centerline of the X-axis distance L and the middle arc line of Step 2 as the center, draw the tangent circle of the theoretical profile in Step 1. Using the intersection of the centerline of the X-axis distance L offset L / 3 in the forward and backward directions and the middle arc line of Step 2 as the center, draw the tangent circle of the theoretical profile in Step 1. Step 4: Based on the deformation of the blade forming, expand the diameter of the three circles in Step 3 to obtain three new circles. Draw arcs tangent to the upper and lower halves of each of the three new circles to obtain an upper and lower arc, denoted as arc R. 上 Arc R 下 ; Step 5, based on arc R 上 Arc R 下 Together with the new circles at both ends in step 4, a closed pre-forging profile is obtained; Step 6: Repeat steps 2 to 5 to complete the theoretical profile operation of the remaining section selected in step 1, and obtain a set of closed pre-forging profiles.

2. The blade pre-forging profile design method according to claim 1, characterized in that, In step 1, the distance from section A0 to section N is S; the intermediate section is the data calculated from A0 for every S / m increase in position, and the section closest to both sides of this data is selected to form a set of m+1 theoretical profiles from section A0 to section N for pre-forging design; the range of m is 2, 3, 4, 5, 6.

3. The blade pre-forging profile design method according to claim 1, characterized in that, In step 3, remove the tangent circle from step 2, retain the theoretical profile from step 1 and the middle arc from step 2. Draw a tangent circle to the theoretical profile with the intersection of the centerline at a distance L along the X-axis and the middle arc as the center, with a diameter of ΦT0. Draw tangent circles to the theoretical profile with the intersection of the centerline at a distance L / 3 along the X-axis and the middle arc as the center, with diameters of ΦT1 and ΦT2 respectively.

4. The blade pre-forging profile design method according to claim 1, characterized in that, In step 4, the deformation range of the blade forming is between 20% and 80%.

5. The blade pre-forging profile design method according to claim 4, characterized in that, When the blade is made of TC4 titanium alloy, the deformation during blade forming is 50%.

6. The blade pre-forging profile design method according to claim 1, characterized in that, In step 5, the new circle at the leading edge is moved from the arc R. 上 Arc R 下 At the tangent point, break the arc on the left and retain it, denoted as R1. Then, connect the new circle at the rear edge to the arc R. 上 Arc R 下 At the tangent point, the arc on the right is broken and retained, denoted as R2. Thus, the arc R1 and the curve R... 上 Circular arc R2, Arc R 下 This forms a closed pre-forged profile.

7. The blade pre-forging profile design method according to claim 1, characterized in that, In step 6, a three-dimensional model of the later pre-forging part is performed based on the obtained set of closed pre-forging part profiles.

8. A blade pre-forging, characterized in that, Using the blade pre-forging profile design method according to any one of claims 1 to 7, a set of closed pre-forging profiles is obtained for the three-dimensional modeling of the pre-forging in the later stage; based on the three-dimensional modeling of the pre-forging, a CNC machine tool is used to process the mold of the pre-forging, and the mold is used to forge the pre-forging.

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