A method for compensating for shortened chord length during blade profile milling

Abstract

This invention belongs to the field of milling technology for thin-walled blade surfaces of aero-engines, specifically relating to a compensation method for shortening the chord length during blade surface milling. The compensation method includes the following steps: Step 1, obtaining the leading edge thickness deviation Δh after precision milling of the nth (n = 1, 2, 3…) section of the blade surface. qn Step 2: Obtain the leading edge chord length deviation ΔA after precision milling of the nth (n = 1, 2, 3...) section of the profile. qn Step 3: Calculate the actual compensation value Δ of the leading edge chord length of each section. qn (n = 1, 2, 3…); Step 4: Compensate for the leading edge chord length of each section; Step 5: Construct new trailing edge profiles for each section; Step 6: Regenerate the machining model; Step 7: Machining according to the new profile model and inspecting again. By using the compensation method of this invention, the milling accuracy of the leading and trailing edges of the blade is greatly improved, and the chord length deviation distribution is more reasonable, which is beneficial to improving the performance of the product.

Description

Technical Field

[0001] This invention belongs to the field of milling technology for thin-walled blade profiles of aero-engines, and specifically relates to a compensation method for the shortening of chord length during blade profile milling. Background Technology

[0002] Aircraft engine compressor blades are typically designed as thin-walled, weak-rigid structures. The milling of their blade profiles, particularly the inlet and outlet edge fillets, often results in a chord length that is less than the length specified in the model or design drawings due to the small edge thickness and the angle of the cutting tool. Therefore, solving the problem of shortened chord length during milling is a key issue that needs to be addressed in precision milling of blade profiles. Summary of the Invention

[0003] The purpose of this invention is to provide a compensation method for the shortening of chord length during blade profile milling, thereby solving the problem of shortening chord length in thin-walled compressor blade profile milling and improving the pass rate.

[0004] A method for compensating for shortened chord length during blade profile milling includes the following steps:

[0005] Step 1: Obtain the leading edge thickness deviation Δh after precision milling of the nth (n = 1, 2, 3...) section of the profile. qn

[0006] By measuring the blade cross-section data using contact or non-contact measuring equipment, the deviation Δh of the leading edge thickness from the chord length of each cross-section to the length specified in the model or design drawings is obtained. qn ;

[0007] The actual thickness H of the airfoil at the leading edge L1 length of the nth (n = 1, 2, 3...) section is measured. qn Based on the design drawings, the leading edge L1 length of each airfoil section is obtained, and the theoretical thickness h is processed. qn The leading edge thickness deviation Δh of each section qn H represents the actual thickness of the airfoil at the leading edge L1 length of each section. qn Subtract the theoretical thickness h of the airfoil at the leading edge L1 length of each section. qn ;

[0008] Step 2: Obtain the leading edge chord length deviation ΔA after precision milling of the nth (n = 1, 2, 3...) section of the profile. qn

[0009] The measured value A of the leading edge chord length of the nth (n = 1, 2, 3...) section was obtained from the surface measurement report after precision milling. qn Based on the design drawings, obtain the theoretical value NA of the leading edge chord length of each section. qn Measured value A of the leading edge chord length of each section qn Compared with the theoretical value NAqn The difference is the leading edge chord length deviation ΔA. qn ;

[0010] Step 3: Calculate the actual compensation value Δ of the leading edge chord length of each section. qn (n = 1, 2, 3...)

[0011] The thickness deviation at the leading edge of each section is half of Δh. qn / 2, minus the leading edge chord length deviation △A qn The actual compensation value Δ of the leading edge chord length of each section is obtained. qn =△h qn / 2-△A qn That is, the actual compensation value Δ of the leading edge chord length of the first section. q1 =△h q1 / 2-△A q1 , ..., △ qn =△h qn / 2-△A qn ;

[0012] Step 4: Compensation of the leading edge chord length of each section

[0013] Step 4.1 Create the leaf basin and leaf back cross-section lines.

[0014] Based on the cross-sectional data points given in the design drawings, draw the leaf base and leaf back cross-sectional lines by connecting the points. Generally, the leaf base and leaf back cross-sectional lines are drawn to the tangent points of the front and rear edges.

[0015] Step 4.2 Draw the leading edge transition fillet R for each section. qn (n = 1, 2, 3...)

[0016] According to the coordinates (Xqn, Yqn) and radius R of the design drawings qn Data, draw the leading edge transition fillet R qn ;

[0017] Step 4.3 Extend the cross-sectional lines of the leaf base and leaf back.

[0018] Extend the profile of the leaf base and leaf back section lines near the front and rear edges according to the curvature of the section lines. The extension distance should be greater than 1 to 2 times the actual compensation value of the front edge chord length in step 3, i.e., (1 to 2)△ qn ;

[0019] Step 4.4 Construct a new leading edge transition fillet R qn新

[0020] The initial R is the size of the leading edge transition R in the design drawing. qn Adjust the newly constructed leading edge transition R qn新 The size, the distance between the centers of the two circles should be equal to Δqn;

[0021] Step 4.5 Forming a new leading edge profile

[0022] Cut the excess extension of the cut basin and back section line to the newly constructed fillet R. qn新 The tangent point, and R qn新 Trim off the excess parts to form new leading edge contours for each section;

[0023] Step 5: Construct new trailing edge profiles for each cross-section.

[0024] Repeat steps 1 to 4 to obtain the tail edge thickness deviation Δh for each section. hn Tail edge chord length deviation △A hn and the actual compensation value of chord length △ hn ; forming new trailing edge profiles for each cross section.

[0025] Step 6: Regenerate the machining model;

[0026] After forming the front and rear edge contours of the new cross sections 1, 2, 3..., complete the construction of the new cross section lines, and connect the newly formed cross section lines 1, 2, 3... to form a new surface model;

[0027] Step 7: Machining according to the new surface model and inspecting again.

[0028] After machining according to the new profile model and re-inspecting, check the actual compensation value Δ of the leading and trailing edge chord lengths of each section. qn , △ qn When the value is ≤0 (n=1, 2, 3…), the compensation for the shortening of the processing chord length is achieved; otherwise, the compensation process steps 1 to 6 are repeated.

[0029] The technical effects of this invention are as follows:

[0030] By using the compensation method of this invention, the milling accuracy of the leading and trailing edges of the blade is significantly improved, and the chord length deviation distribution is more reasonable, which is beneficial to improving the performance of the product. Through the above method, the blade processing qualification rate is improved, reducing scrap losses by 500,000 yuan annually, achieving good results. With the increase in the company's production capacity and the promotion and application of this technology, the economic benefits will be significantly enhanced. Attached Figure Description

[0031] Figure 1 Blade leading and trailing edge thickness and chord length deviation

[0032] Figure 2 Draw the cross-sectional line of the basin back

[0033] Figure 3 Drawing the leading edge theory R qn

[0034] Figure 4 Extend the front edge of the basin back section line

[0035] Figure 5 Construct a new leading edge transition fillet R qn新 Detailed Implementation

[0036] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0037] A method for compensating for shortened chord length during blade profile milling includes the following steps:

[0038] Step 1: Obtain the thickness deviation Δh of the leading edge of the milled profile. qn

[0039] By measuring the blade cross-section data using contact or non-contact measuring equipment, the deviation Δh of the leading edge thickness from the chord length of each cross-section to the length specified in the model or design drawings is obtained. qn ;

[0040] like Figure 1 As shown, the actual thickness of the airfoil at the leading edge L1 = 5 mm of the first section is measured to be H. q1 The thickness is 1.55mm. Based on the design drawings, the leading edge L1 length of each airfoil section is obtained, and the theoretical thickness h is processed. q1 The thickness deviation at the leading edge of the first section is 1.45 mm, Δh. q1 =H q1 -h q1 =1.55-1.45=0.1mm;

[0041] The leading edge thickness deviation Δh of sections 2, 3, 4... is obtained sequentially using this method. q2 , △h q3 , △h q4 …

[0042] Step 2: Obtain the deviation ΔA of the leading edge chord length of the milled profile. qn

[0043] like Figure 1 As shown, the measured value A of the leading edge chord length of the first section was obtained from the surface measurement report after precision milling. q1 The theoretical value NA of the leading edge chord length of the first section is 23.52 mm, obtained from the design drawings. q1 =23.50mm, measured value A of the leading edge chord length of the first section. q1 Compared with the theoretical value NA q1 The difference is the leading edge chord length deviation ΔA. q1 =23.52-23.50=0.02mm;

[0044] The leading edge chord length deviation ΔA of the 2nd, 3rd, 4th... sections is obtained sequentially using this method. q2 △Aq3 △A q4 …

[0045] Step 3: Calculate the actual compensation value Δ of the leading edge chord length of the cross section. qn

[0046] Half of the leading edge thickness deviation of the first section, i.e., Δh q1 / 2, minus the leading edge chord length deviation △A q1 The actual compensation value Δ of the leading edge chord length of the first section is obtained. q1 =△h q1 / 2-△A q1 That is, the actual compensation value Δ of the leading edge chord length of the first section. q1 =△h q1 / 2-△A q1 =0.1 / 2 - 0.02 = 0.03 mm;

[0047] The actual compensation value Δ of the leading edge chord length of the 2nd, 3rd, 4th... sections is obtained sequentially using this method. q2 , △ q3 , △ q4 …

[0048] Step 4: Compensation of the leading edge chord length of each section

[0049] Step 4.1 Create the leaf base and leaf back section lines for the first section.

[0050] like Figure 2 As shown, based on the cross-sectional data points given in the design drawings, the blade base and blade back cross-sectional lines of the first section are drawn by connecting the points. Generally, the blade base and blade back cross-sectional lines are drawn to the tangent points of the front and rear edges.

[0051] Step 4.2 Draw the fillet R at the leading edge of the first section. q1

[0052] like Figure 3 As shown, draw the fillet R at the leading edge of the first section according to the coordinates and radius data in the design drawings. q1 =0.15mm; Step 4.3 Extend the blade tip and blade back section lines of the first section.

[0053] like Figure 4 As shown, the profiles of the leaf base and leaf back sections near the leading and trailing edges are extended according to the curvature of the section lines of the first section. The extension distance is twice the actual compensation value of the leading edge chord length of the first section in step 3, i.e., 2Δ. qn =0.06mm;

[0054] Step 4.4 Construct the new leading edge transition fillet R of the first section q1新

[0055] like Figure 5 As shown, the initial R is taken as the size of the leading edge transition R of the first section of the design drawing. q1 Adjust the newly constructed leading edge transition R q1新 The size is such that the distance between the two centers should be equal to Δq1 = 0.03 mm.

[0056] Step 4.5 Forming the new leading edge profile of the first section

[0057] Cut the excess extension of the cut basin and back section line to the newly constructed fillet R. q1新 The tangent point, and R q1新 Trim off the excess portion to form the new leading edge profile of the first section;

[0058] Follow steps 4.1 to 4.5 to complete the construction of the new leading edge contours for sections 2, 3, 4...;

[0059] Step 5: Construct new trailing edge profiles for each cross-section.

[0060] Repeat steps 1-4 to obtain the thickness deviation Δh of the leading and trailing edges of each section. hn Tail edge chord length deviation △A hn and the actual compensation value of chord length △ hn Complete the construction of new trailing edge profiles for each section;

[0061] Step 6: Regenerate the machining model;

[0062] After completing the construction of the new leading and trailing edge contours of sections 1, 2, 3..., the construction of new section lines is completed. The newly formed section lines 1, 2, 3... are then connected to form a new surface model.

[0063] Step 7: Machining according to the new surface model and inspecting again.

[0064] After machining according to the new profile model and re-inspection, the actual compensation value Δ of the leading and trailing edge chord lengths of each section is recalculated. qn , △ hn When ≤0, (n=1, 2, 3…), compensation for the shortening of the chord length during processing is achieved; if individual cross-sections have a compensation value Δ qn or △ hn When the value is greater than 0, steps 1 to 7 are repeated for this section.

Claims

1. A method of compensating for chord shortening in blade profile milling, characterized by, The method comprises the following steps: Step 1, obtain the thickness deviation of the leading edge △h after the n (n = 1, 2, 3...) cross section of the profile is precisely milled qn The blade section data is measured by contact or non-contact measuring equipment, and the leading edge thickness deviation Ah of each section chord length is obtained relative to the model or design paper set length qn ; Step 2, the deviation of the chord length of the leading edge after the profile nth (n = 1, 2, 3...) section is precisely milled qn Step 3, find the actual compensation value of the chord length of the leading edge of each section △ qn (n = 1, 2, 3...) Half of the deviation of the leading edge thickness of each section, i.e. △h qn / 2, minus the deviation of the leading edge chord length △A qn , to obtain the actual compensation value of the leading edge chord length △A qn of each section qn =△h qn / 2-△A Step 4, compensation of chord length of each section The compensation of chord length of each section is specifically: Step 4.1, drawing of blade basin and blade back section lines According to the section data points given by the design drawing, the blade basin and blade back section lines are drawn by point connection, and the blade basin and blade back section lines are generally drawn to the tangent points of the leading edge and the trailing edge; Step 4.2 Draw the fillet R of each section leading edge qn (n = 1, 2, 3...) (Xqn, Yqn) coordinates and radius R according to design drawing qn Data, draw the leading edge fillet R qn ; Step 4.3, extension of the blade basin and blade back section lines The curvature of the cross-sectional line of the leaf basin and the leaf back is used to extend the profile line of the leaf basin and the leaf back near the front and rear edges, and the extension distance should be greater than 1-2 times the actual compensation value of the chord length of the front edge in step 3, that is, (1-2) Δ qn ; Step 4.4 Building new leading edge transition fillet R qn新 The size of the front edge adapter R is taken as the initial R qn , adjust the size of the newly constructed front edge adapter R qn新 The distance between the two circle centers should be equal to △qn; Step 4.5, formation of a new leading edge contour Cutting off the excess extension of the back cross-sectional line to the new constructed rounded corner R qn新 of the tangent, and R qn新 Cutting off the excess to form the new leading edge profile of each cross-section; Step 5, construction of a new trailing edge contour of each section Repeat steps 1~4 to obtain the thickness deviation of each section tail edge Δh hn , the chord length deviation of tail edge ΔA hn , and the actual compensation value of chord length Δ hn ; form the new tail edge profile of each section Step 6, regeneration of a processing model After the leading edge and trailing edge contours of the new sections 1, 2, 3… are formed, the new section lines 1, 2, 3… are connected to form a new surface model; Step 7, processing according to the new surface model and re-detection When the new profile model is processed and detected again, the actual compensation value of chord length of each section before and after the edge is checked qn , △ qn ≤0, (n=1, 2, 3…) when, that is, the compensation of the shortening of the processed chord length is achieved, otherwise, repeat the compensation process steps 1-6.

2. The method of claim 1, wherein the chord length shortening compensation is performed by a blade profile milling process. The front edge thickness deviation Δh qn The specific calculation process is as follows: The actual thickness of the blade profile at the leading edge L1 of the nth (n = 1, 2, 3...) cross section is measured as H qn The theoretical thickness h of the leading edge of each cross section is obtained according to the design drawing qn The deviation Ah of the leading edge of each cross section is qn The actual thickness value H of the blade profile at the leading edge L1 of each cross section qn Subtract the theoretical thickness value h of the blade profile at the leading edge L1 of each cross section qn .

3. The method of claim 1, wherein the chord length shortening compensation is performed by: calculating a chord length shortening value for each blade profile point; and adjusting the chord length shortening value for each blade profile point based on a chord length shortening value of a neighboring blade profile point. The front edge chord length deviation ΔA qn The specific calculation process is as follows: According to the profile measurement report after fine milling, the measured value A of the leading edge chord length of the nth (n = 1, 2, 3…) section is obtained qn , the theoretical value NA of the leading edge chord length of each section is obtained according to the design drawing qn , the difference between the measured value A of the leading edge chord length of each section qn and the theoretical value NA qn is the deviation ΔA of the leading edge chord length qn .

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