A design method for plate blanks used for rolling deep-bend blades

Abstract

The present invention provides a design method for a plate-shaped blank for rolling deep-bend blades, which relates to the technical field of aero-engine blade manufacturing. The present invention confirms the bend angle of the blade, cuts off a blade section every 1 mm along the entire length of the blade, and evenly divides the entire blade into several sections along the blade body direction. The section spacing in the straight blade body section is L = 5mm-7mm, and each bend angle includes no less than three sections, namely, the entry bend section, the middle bend section, and the exit bend section. The section spacing at the bend angle is M = 2mm-3mm; the cross-sectional blade shape is unfolded into a plane and the blade shape is added with a margin, the section distance is calculated, and the design method of the deep-bend blade plate-shaped blank is completed; the present invention improves the overall rolling quality of the blade, and the blade tolerance distribution is more reasonable, which is conducive to improving the performance of the product. Through the above method, the processing qualification rate of the blade is improved, and the waste loss can be reduced by millions of yuan each year, achieving good results.

Description

Technical Field

[0001] The invention relates to the technical field of aero-engine blade manufacturing, and in particular to a design method for a plate-shaped blank for rolling deep-bend blades. Background Art

[0002] Aircraft engine blade manufacturing technology is one of the most complex technologies in the turbine machinery manufacturing industry, and it also involves a wide range of specialized fields within the machinery manufacturing industry. Therefore, the level of blade manufacturing technology reflects the level of engine manufacturing technology to a certain extent.

[0003] Precision cold roll forming of blade profiles involves passing a blade blank through a pair of rotating roller dies, where the pressure of the die grooves causes the metal to plastically deform, thereby achieving the desired blade shape. This process offers significant advantages in manufacturing cost, production efficiency, and product performance compared to CNC milling, precision forging, and precision electrolysis.

[0004] Stator blades without mounting plates at either end only have a three-dimensional curved blade body profile, which is subsequently welded together with other components to form a fan-shaped segment. The stator blades of a certain engine model without mounting plates are made of GH4169 alloy, which features large variations in profile curvature, a swept-back bend, a large twist angle, a waisted intake and exhaust edge, and a significant difference in thickness between the intake and exhaust edges. The rolled blanks for these blades are 2 or 2.5 mm thick sheets, which undergo two roll forming cycles to complete the profile. The rationality of the blank design after rough rolling and before finish rolling seriously affects the accuracy and stability of the blade rolling process. The original blank design method was designed for straight rolled blades. According to this method, the process of rolling deeply curved blades exposed lateral bending caused by unbalanced metal flow at the bend. Multiple manual corrections were required to achieve a state that was basically satisfactory for use. The lack of a mastered design method for plate blanks used in rolling deeply curved blades affected the rolling quality of the blades. Summary of the Invention

[0005] In response to the problems existing in the prior art, the present invention provides a design method for plate blanks for rolling deep-bend blades. In order to solve the problem that the exhaust edge of the blade has severe bending, which causes increased material consumption on the exhaust edge and lateral bending during the rolling process, the blade profile is divided into a straight blade body area and an angle area, and the blade cross-sections in different areas are subjected to a variable proportional coefficient margin addition method to design the blank before finishing rolling, thereby reducing the lateral bending and blade profile distortion of the blade during the rolling process and improving the blade rolling qualification rate.

[0006] The technical solution adopted by the present invention is:

[0007] A method for designing a plate-shaped blank for rolling a deep-bend blade comprises the following steps:

[0008] Step 1: Confirm the bending angle area of ​​the blade. Cut a blade section every 1mm along the entire length of the blade to obtain the chord angle of each section. The part where the chord angle of the blade section changes by no more than 0.5° within 1mm is the straight blade area, and the part where the chord angle of the blade section changes by more than 0.5° within 1mm is the bending angle area.

[0009] Step 2: Cut several cross sections along the blade body direction. The cross section spacing in the straight blade body area is L = 5mm-7mm. Cut at least three cross sections in each bend area, including the bend entry section, several bend mid-sections, and the bend exit section. The cross section spacing in the bend area is M = 2mm-3mm.

[0010] Step 3: Expand the cross-section leaf shape into a plane; the specific expansion method is as follows:

[0011] Step 3.1: Use a computer program or connect the centers of inscribed circles to draw the mid-arc lines of each leaf section.

[0012] Step 3.2: Divide the middle arc into several segments, make perpendicular lines to the middle arc, and intersect them at the basin and back surfaces;

[0013] Step 3.3: Find the Cmax position, which is the position with the maximum cross-section thickness. Draw a horizontal line at the intersection of Cmax and the leaf shape as the bottom surface of the leaf.

[0014] Step 3.4: With point M as the center of rotation, and point M as the midpoint of the maximum vertical thickness of the cross section, rotate the remaining perpendicular lines of the mid-arc, and rotate the endpoints of these perpendicular lines of the mid-arc to the bottom surface of the horizontal line obtained in step 3.3;

[0015] Step 3.5: Rotate the endpoints of the perpendicular line of the mid-arc line in sequence to rotate the entire leaf shape into a plane;

[0016] Step 4: Add margin to the leaf shape;

[0017] The unfolded flat leaf shape is divided into several segments with a spacing of 1.5mm-2.5mm. The length of each segment is the thickness at that point.

[0018] There are two ways to add allowance to the leaf section:

[0019] (1) The straight section, the bend section, and the bend section are added with a fixed proportional allowance. The length of each line segment is enlarged by the proportional allowance coefficient K, and the endpoints are connected with a spline to form a new spline.

[0020] (2) The method of adding the bending section is to add the variable allowance, as follows:

[0021] Taking the center point of Cmax as the dividing point, the blade section is divided into two sections: the smooth intake side and the curved exhaust side. For the smooth intake side, a uniform proportional margin coefficient S is used, while for the curved exhaust side, a variable proportional margin is used that gradually increases from the dividing point to the edge. The maximum proportional margin coefficient N at the edge is equal to S plus 0.3-0.7;

[0022] The principle for selecting the value of A is:

[0023] (1) The selection of the proportional margin coefficient of 0.3-0.7 is based on the degree of curvature of the blade. The greater the curvature, the greater the deformation value; the smaller the curvature, the smaller the deformation value;

[0024] (2) If there are multiple bend sections, the same N value is used;

[0025] Step 5: Calculate the cross-sectional distance and complete the design of the plate blank for deep-bend blade rolling;

[0026] During the rolling process, the blade body lengthwise expands according to the principle of constant volume. Therefore, the cross-sectional distance of the blade blank must also be reduced. The cross-sectional distance is calculated as follows:

[0027] L AB新 =L AB原 (C maxA +C maxB ) / (K A C maxA +K B C maxB )

[0028] Where, L AB新 is the new section distance, L AB原 is the original cross-sectional distance, K A , K B are the deformation coefficients of A and B, C maxA 、C maxB The positions of maximum vertical thickness of the sections A and B respectively.

[0029] The beneficial effects of adopting the above technical solution are:

[0030] This invention proposes a design method for plate blanks used in deep-bend blade rolling. This method improves the overall rolling quality of the blades and provides a more rational distribution of deformation during rolling, thereby enhancing product performance. This method has significantly increased the blade processing yield, saving millions of yuan in annual scrap losses. With the company's increased production capacity and widespread adoption, the economic benefits are expected to increase significantly. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1Schematic diagram of the blade structure in an embodiment of the present invention;

[0032] Figure 2 Schematic diagram of the middle arc line of the cross-section blade shape in an embodiment of the present invention;

[0033] Figure 3 Schematic diagram of the vertical line of the middle arc in the embodiment of the present invention;

[0034] Figure 4 Schematic diagram of the Cmax position in an embodiment of the present invention;

[0035] Figure 5 Schematic diagram of the position of point M in an embodiment of the present invention;

[0036] Figure 6 A schematic diagram of a rotating plane in an embodiment of the present invention;

[0037] Figure 7 Schematic diagram of a spline in an embodiment of the present invention. DETAILED DESCRIPTION

[0038] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0039] A method for designing a plate-shaped blank for rolling a deep-bend blade comprises the following steps:

[0040] Step 1: Confirm the bend area of ​​the blade and cut a blade section every 1mm along the entire length of the blade, such as Figure 1 As shown, the chord angle of each section is obtained. The portion of the blade section where the chord angle changes by no more than 0.5° within 1 mm is the straight blade area, and the portion where the chord angle changes by more than 0.5° within 1 mm is the curved angle area.

[0041] Step 2: Cut several cross sections along the blade body direction. The cross section spacing in the straight blade body area is L = 5mm-7mm. Cut at least three cross sections in each bend area, including the bend entry section, several bend mid-sections, and the bend exit section. The cross section spacing in the bend area is M = 2mm-3mm.

[0042] Step 3: Expand the cross-section leaf shape into a plane; the specific expansion method is as follows:

[0043] Step 3.1: Use a computer program or connect the centers of the inscribed circles to draw the mid-arc lines of the leaf shapes in each section, such as Figure 2 As shown;

[0044] Step 3.2: Divide the middle arc into several segments, make perpendicular lines to the middle arc, and intersect them at the basin and back surfaces, such as Figure 3 As shown;

[0045] Step 3.3: Find the Cmax position, which is the position with the maximum thickness of the section. Figure 4 As shown, a horizontal line is drawn at the intersection of Cmax and the leaf shape as the bottom surface of the leaf;

[0046] Step 3.4: Take point M as the rotation center. Point M is the midpoint of the maximum vertical thickness of the cross section. Figure 5 As shown, rotate the remaining perpendicular lines of the median arc, and rotate the endpoints of these perpendicular lines of the median arc to the bottom surface of the horizontal line obtained in step 3.3;

[0047] Step 3.5: Rotate the endpoints of the vertical line of the mid-arc in sequence to rotate the entire leaf shape into a plane, as shown in the following example: Figure 6 As shown;

[0048] Step 4: Add margin to the leaf shape;

[0049] The unfolded flat leaf shape is divided into several segments with a spacing of 1.5mm-2.5mm. The length of each segment is the thickness at that point.

[0050] There are two ways to add allowance to the leaf section:

[0051] (1) The straight section, the bend section, and the bend section are added with a fixed proportional allowance. The length of each line segment is enlarged by the proportional allowance coefficient K, and the endpoints are connected with a spline to form a new spline.

[0052] (2) The method of adding the bending section is to add the variable allowance, as follows:

[0053] Taking the center point of Cmax as the dividing point, the blade section is divided into two sections: the smooth intake side and the curved exhaust side. For the smooth intake side, a uniform proportional margin coefficient S is used, while for the curved exhaust side, a variable proportional margin is used that gradually increases from the dividing point to the edge. The maximum proportional margin coefficient N at the edge is equal to S plus 0.3-0.7;

[0054] The principle for selecting the value of A is:

[0055] (3) The selection of the proportional margin coefficient of 0.3-0.7 is based on the degree of curvature of the blade. The greater the curvature, the greater the deformation value; the smaller the curvature, the smaller the deformation value;

[0056] (4) If there are multiple bend sections, the same N value is used;

[0057] Step 5: Calculate the section distance and complete the design of the deep-bend blade blank, such as Figure 7 As shown;

[0058] During the rolling process, the blade body lengthwise expands according to the principle of constant volume. Therefore, the cross-sectional distance of the blade blank must also be reduced. The cross-sectional distance is calculated as follows:

[0059] L AB新 =L AB原 (C maxA +C maxB ) / (K A C maxA +K B C maxB )

[0060] Where, L AB新 is the new section distance, L AB原 is the original cross-sectional distance, K A , K B are the deformation coefficients of A and B, C maxA 、C maxB The positions of maximum vertical thickness of the sections A and B respectively.

[0061] In this embodiment, two embodiments are specifically listed for illustration.

[0062] Example 1:

[0063] The total length of a certain level of blade is 70mm. After calculation, there are two deep bend areas on the exhaust edge of the blade, and the lengths of the two deep bends are 6mm and 8mm respectively. The calculation section is selected on the blade. The spacing between the straight blade section is about 7mm. A total of 9 straight blade sections are selected. The section spacing of the mid-bend section is 2mm, and a total of 5 mid-bend sections are obtained.

[0064] According to the steps specified in the above technical solution, unfold each blade cross-section into a plane. For straight blade sections, add allowances proportional to the profile. For curved sections, calculate the location of the maximum thickness of the blade and add allowances proportionally from the maximum thickness location to the inlet edge, with a proportional coefficient of 1.5. The deformation at the exhaust edge increases by 0.6 to 2.1. The ratio of allowances for the area from the maximum thickness location to the exhaust edge is gradually increased from 1.5 to 2.1. After completing the allowance additions for all sections, complete the design according to the steps specified in the technical solution.

[0065] Example 2:

[0066] The total length of a certain level of blade is 50mm. There are two deep bend areas on the exhaust edge of the blade. The lengths of the two deep bends are 4mm and 6mm respectively. The calculation section is selected on the blade. The cross-sectional spacing of the straight blade section is about 5mm. A total of 9 straight blade sections are selected. The cross-sectional spacing of the mid-bend section is 2mm, and a total of 3 mid-bend sections are obtained.

[0067] According to the steps specified in the above technical solution, unfold each blade cross-section into a plane. For straight blade sections, add allowances proportional to the profile. For curved sections, calculate the location of the maximum thickness of the blade and add allowances proportionally from the maximum thickness location to the inlet edge, with a proportional coefficient of 1.4. The deformation at the exhaust edge increases by 0.4 to 1.8. The ratio of allowances for the area from the maximum thickness location to the exhaust edge increases gradually from 1.4 to 1.8. After completing the allowance additions for all sections, complete the design according to the steps specified in the technical solution.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or make equivalent replacements for some or all of the technical features therein. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope defined by the claims of the present invention.

Claims

1. A method for designing a plate blank for rolling a deep-bend blade, characterized by: The following steps are involved: Step 1: Identify the blade's curved area. Cut a blade section every 1 mm along the entire length of the blade and obtain the chord angle of each section. The section where the chord angle of the blade section changes by no more than 0.5° within 1 mm is considered a straight blade area, and the section where the chord angle of the blade section changes by more than 0.5° within 1 mm is considered a curved area. Step 2: Cut several cross sections along the blade body direction. The cross section spacing in the straight blade body area is L = 5mm-7mm. Cut at least three cross sections in each bend area, including the bend entry section, several bend mid-sections, and the bend exit section. The cross section spacing in the bend area is M = 2mm-3mm. Step 3: Expand the cross-section leaf shape into a plane; Step 4: Add margin to the leaf shape; The unfolded flat leaf shape is divided into several segments with a spacing of 1.5mm-2.5mm. The length of each segment is the thickness at that point. Step 5: Calculate the section distance and complete the design of the plate blank for deep-bend blade rolling.

2. The method for designing a plate blank for rolling a deep-bend blade according to claim 1, characterized in that: The step 3 specifically includes the following steps: Step 3.1: Use a computer program or connect the centers of inscribed circles to draw the mid-arc lines of each leaf section. Step 3.2: Divide the middle arc into several segments, make perpendicular lines to the middle arc, and intersect them at the basin and back surfaces; Step 3.3: Find the Cmax position, which is the position with the maximum cross-section thickness. Draw a horizontal line at the intersection of Cmax and the leaf shape as the bottom surface of the leaf. Step 3.4: With point M as the center of rotation, and point M as the midpoint of the maximum vertical thickness of the cross section, rotate the remaining perpendicular lines of the mid-arc, and rotate the endpoints of these perpendicular lines of the mid-arc to the bottom surface of the horizontal line obtained in step 3.3; Step 3.5: Rotate the endpoints of the perpendicular line of the mid-arc line one by one to rotate the entire leaf shape into a plane.

3. The method for designing a plate blank for rolling a deep-bend blade according to claim 1, characterized in that: There are two ways to add the margin described in step 4: (1) The straight section, the bend section, and the bend section are added with a fixed proportional allowance. The length of each line segment is enlarged by the proportional allowance coefficient K, and the endpoints are connected with a spline to form a new spline. (2) The method of adding the bending section is to add the variable allowance, as follows: Taking the center point of Cmax as the dividing point, the blade section is divided into two sections: the smooth intake side and the curved exhaust side. For the smooth intake side, a uniform proportional margin coefficient S is selected, while for the curved exhaust side, a variable proportional margin is used that gradually increases from the dividing point to the edge. The maximum proportional margin coefficient N at the edge is equal to S plus 0.3-0.

7. The principle for selecting the value of A is: (1) The selection of the proportional margin coefficient of 0.3-0.7 is based on the degree of curvature of the blade. The greater the curvature, the greater the deformation value; the smaller the curvature, the smaller the deformation value; (2) If there are multiple bend sections, the same N value is used.

4. The method for designing a plate blank for rolling a deep-bend blade according to claim 1, characterized in that: The calculation of the cross-sectional distance in step 5 is specifically that, due to the blade length lengthening in the rolling process according to the principle of constant volume, the cross-sectional distance of the blade blank also needs to be reduced. The cross-sectional distance is calculated as follows: L AB新 =L AB原 (C maxA +C maxB ) / (K A C maxA +K B C maxB ) Where, L AB新 is the new section distance, L AB原 is the original cross-sectional distance, K A , K B are the deformation coefficients of A and B, C maxA 、C maxB The positions of maximum vertical thickness of the sections A and B respectively.

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