CN103136426A - Aviation blade circular arc leading-trailing edge process model generation method - Google Patents

Abstract

The invention discloses a method for generating a process model of an arc-shaped leading and trailing edge of an aviation blade, which is used to solve the technical problem that it is difficult to establish a process model for processing a circular-arc-shaped leading and trailing edge blade in the prior art. The technical solution is firstly based on the characteristic that the blade leading edge curve is tangent to the blade pot and the blade back curve, using geometric information such as the two tangent lines at the end points of the blade leading edge curve and its angle bisector, and the leading edge point of the blade, and according to the design The distance between the leading edge point of the determined leading edge process model and the leading edge point of the original CAD model is determined to determine the leading edge process model that meets the requirements. In engineering applications, the user only needs to set the process margin of the leading and trailing edges according to the actual needs, and can quickly obtain accurate process models of the arc-shaped leading and trailing edge blades, which are used to guide the high-quality processing of aviation blades.

Description

Method for generating process model of arc-shaped leading and trailing edges of aeronautical blades

technical field

The invention relates to a method for generating a process model of the leading and trailing edges of an aviation blade, in particular to a method for generating a process model of an arc-shaped leading and trailing edge of an aviation blade.

Background technique

The interior of an aero-engine is basically composed of a series of blades, such as turbine blades, compressor blades, fan blades, etc.; as the core part of the engine, the models of aero-blades are mostly free-form surfaces, and the molding process is relatively complicated; at the same time, the shape of the blade surface The level of design and manufacturing determines the performance of the engine to a large extent; therefore, the manufacturing technology of aviation blades is one of the more complicated technologies in the mechanical manufacturing industry.

The manufacture of aviation blades mainly includes methods such as investment casting, numerical control machining and point solution machining. Using CNC machining to process thin-walled blades is prone to large deformation problems, and due to the problems of the process system itself composed of workpieces, tools, fixtures and machine tools, overcutting or under-processing will occur during blade processing. ; If it is processed directly based on the blade CAD model, it will lead to the problem that the shape accuracy of the blade is difficult to control, thereby affecting the processing quality of the blade. The improvement of the processing quality of the blade in the prior art is based on the idea of reverse deformation to compensate the error in the blade forming process; the research on the blade process model is mainly based on the investment casting method of the blade to establish the casting process model. For the NC machining of aviation thin-walled blades, on the basis of the CAD model of the blade, considering the margin distribution of the blade basin, blade back, leading edge and trailing edge area of the blade body, the NC machining process model of the blade is established, which is very important for ensuring The processing quality of the blade has important application value.

Contents of the invention

In order to overcome the deficiency that it is difficult to establish a process model for processing arc-shaped leading and trailing edge blades in the prior art, the invention provides a method for generating a process model for an aeronautical blade with arc-shaped leading and trailing edges. According to the characteristic that the leading edge curve of the blade is tangent to the blade basin and the blade back curve, the method uses geometric information such as the two tangent lines at the end points of the leading edge curve of the blade and its angle bisector, as well as the leading edge point of the blade, and according to the set The distance between the leading edge point of the leading edge process model and the leading edge point of the original CAD model is used to determine the leading edge process model that meets the requirements. In engineering applications, the user only needs to set the process margin of the leading and trailing edges according to the actual needs, and can quickly obtain accurate process models of the arc-shaped leading and trailing edge blades, which are used to guide the high-quality processing of aviation blades.

The technical solution adopted by the present invention to solve the technical problem is: a method for generating a process model of an arc-shaped leading and trailing edge of an aviation blade, which is characterized in that it includes the following steps:

Step 1, read in the aviation blade CAD model;

Step 2: Cut a section of the aviation blade along the vertical Z direction, record the tangent points of the leading edge curve L and the blade pot and the blade back as P ₁ and P ₂ respectively, and calculate the tangent lines L ₁ , L ₂ and the two points at P ₁ and P ₂ The intersection of tangents O(O _x ,O _y );

The equation of the circle where the leading edge curve is located is: (xx ₀ ) ² +(yy ₀ ) ² =r ² where the center of the circle is (x ₀ ,y ₀ ) and the radius is r; the slope of any point on the calculated curve is k _i =( x _i -x ₀ )/(y _i -y ₀ ), where (xi _, y _i ) is any point on the curve, then the tangent equation of any point (xi _, y _i ) on the curve: y=y _i + _ki (xx _i );

The tangent line L ₁ at this point obtained from the slope k ₁ at P ₁ is respectively y=y ₁ +k ₁ (xx ₁ ), and the tangent line L ₂ at the two points obtained from the slope k ₂ at P ₂ is respectively y=y ₂ +k ₂ (xx ₂ ); then the coordinates of the intersection point O(O _x ,O _y ) of the two tangents are $(\frac{{\mathrm{the\; y}}_2-k_2{x}_2-{\mathrm{the\; y}}_1+k_1{x}_1}{k_1-k_2},\frac{k_1{k}_2(x_1-x_2)}{k_1-k_2}).$

求出角平分线的切线斜率k，则角平分线为y₃=O_y+k(x₃-O_x)；Step 3. Calculate the angle bisector L ₃ of the angle formed by the two tangents in step 2, using the formula

Find the tangent slope k of the angle bisector, then the angle bisector is y ₃ =O _y +k(x ₃ -O _x );

Step 4. Calculate the intersection point of the angle bisector L ₃ and the leading edge curve L in step 3, which is the leading edge point P ₀ of the arc-shaped leading edge;

Step 5, set the process margin δ, based on the leading edge point P ₀ , along the direction of P ₀ O, find a straight line with a distance of δ to the point P ₀ as L ₄ ;

首先在L₃上找圆心M(m_x,m_y)到L₁、L₂、L₄的距离相等；并求出该距离d_m，作为相切圆M的半径；切点分别记为T₁、T₂、T₃,截取相应的圆弧段，并光滑连结线段T₁P₁｀T₂P₂及圆弧T₁T₂，曲线段P₁T₃P₂即为航空叶片圆弧形前缘工艺模型。Step 6. Find the circle tangent to L ₁ , L ₂ , and L ₄ at the same time, and use the distance formula from the point (x _m , y _m ) to the straight line Ax+By+C=0

First find the distance from the center of circle M(m _x ,m _y ) to L ₁ , L ₂ , and L ₄ on L ₃ to be equal; and find the distance d _m as the radius of the tangent circle M; the tangent points are respectively recorded as T ₁ , T ₂ , T ₃ , intercept the corresponding arc segment, and smoothly connect the line segment T ₁ P ₁ 'T ₂ P ₂ and the arc T ₁ T ₂ , the curve segment P ₁ T ₃ P ₂ is the aviation blade arc Shaped leading edge process model.

The beneficial effect of the present invention is: due to the characteristics that the curve of the leading edge of the blade is tangent to the curve of the blade pot and the back of the blade, the two tangent lines at the end points of the curve of the leading edge of the blade and the bisector of the angle thereof, as well as geometric information such as the leading edge point of the blade are used , and according to the distance between the leading edge point of the set leading edge process model and the leading edge point of the original CAD model, the leading edge process model that meets the requirements is determined. In engineering applications, the user only needs to set the process margin of the leading and trailing edges according to the actual needs, and can quickly obtain accurate process models of the arc-shaped leading and trailing edge blades, which are used to guide the high-quality processing of aviation blades.

The present invention will be described in detail below in conjunction with the accompanying drawings and embodiments.

Description of drawings

Fig. 1 is a flowchart of a method for generating a process model of an arc-shaped leading edge of an aviation blade according to the present invention.

Fig. 2 is a process schematic diagram of a method for generating a process model of an aeronautical blade arc-shaped leading edge according to the method of the present invention.

Fig. 3 is a schematic diagram of a process model of an arc-shaped leading edge of an aviation blade generated by an implementation example of the method of the present invention.

Detailed ways

Refer to Figures 1-3. The specific steps of the method for generating the process model of the arc-shaped leading and trailing edges of the aviation blade of the present invention are as follows:

Step 1, read in the aviation blade CAD model;

Step 2: Cut a section of the aviation blade along the vertical Z direction, record the tangent points of the leading edge curve L and the blade pot and the blade back as P ₁ and P ₂ respectively, and calculate the tangent lines L ₁ , L ₂ and the two points at P ₁ and P ₂ The intersection of tangents O(O _x ,O _y );

The equation of the circle where the leading edge curve is located is: (xx ₀ ) ² +(yy ₀ ) ² =r ² where the center of the circle is (x ₀ ,y ₀ ) and the radius is r; the slope of any point on the calculated curve is k _i =( x _i -x ₀ )/(y _i -y ₀ ), where (xi _, y _i ) is any point on the curve, then the tangent equation of any point (xi _, y _i ) on the curve: y=y _i + _ki (xx _i );

The tangent line L ₁ at this point obtained from the slope k ₁ at P ₁ is respectively y=y ₁ +k ₁ (xx ₁ ), and the tangent line L ₂ at the two points obtained from the slope k ₂ at P ₂ is respectively y=y ₂ +k ₂ (xx ₂ ); then the coordinates of the intersection point O(O _x ,O _y ) of the two tangents are $(\frac{{\mathrm{the\; y}}_2-k_2{x}_2-{\mathrm{the\; y}}_1+k_1{x}_1}{k_1-k_2},\frac{k_1{k}_2(x_1-x_2)}{k_1-k_2}).$

求出角平分线的切线斜率k，则角平分线为y₃=O_y+k(x₃-O_x)；Step 3. Calculate the angle bisector L ₃ of the angle formed by the two tangents in step 2, using the formula

Find the tangent slope k of the angle bisector, then the angle bisector is y ₃ =O _y +k(x ₃ -O _x );

Step 4. Calculate the intersection point of the angle bisector L ₃ and the leading edge curve L in step 3, which is the leading edge point P ₀ of the arc-shaped leading edge;

Step 5, set the process margin δ, based on the leading edge point P ₀ , along the direction of P ₀ O, find a straight line with a distance of δ to the point P ₀ as L ₄ ;

首先在L₃上找圆心M(m_x,m_y)到L₁、L₂、L₄的距离相等；并求出该距离d_m，作为相切圆M的半径；切点分别记为T₁、T₂、T₃,截取相应的圆弧段，并光滑连结线段T₁P₁、T₂P₂及圆弧T₁T₂，曲线段P₁T₃P₂即为航空叶片圆弧形前缘工艺模型。Step 6. Find the circle tangent to L ₁ , L ₂ , and L ₄ at the same time, and use the distance formula from the point (x _m , y _m ) to the straight line Ax+By+C=0

First find the distance from the center of circle M(m _x ,m _y ) to L ₁ , L ₂ , and L ₄ on L ₃ to be equal; and find the distance d _m as the radius of the tangent circle M; the tangent points are respectively recorded as T ₁ , T ₂ , T ₃ , intercept the corresponding arc segment, and smoothly connect the line segment T ₁ P ₁ , T ₂ P ₂ and arc T ₁ T ₂ , the curve segment P ₁ T ₃ P ₂ is the aviation blade arc Shaped leading edge process model.

Application example:

This embodiment is an arc-shaped leading edge blade of a certain type of engine. The circle equation of the arc-shaped leading edge is (x-32.73) ² +(y+3.34) ² =0.28 ² . The cut points are P ₁ (32.77, -3.62), P ₂ (32.71, -3.06);

In conjunction with the accompanying drawings and embodiments, the method for generating the arc-shaped leading and trailing edge process models of the present invention is described in detail, and the specific steps are as follows:

Step 1, read in the blade CAD model;

Step 2: Cut a section of the aviation blade along the vertical Z direction, record the tangent points of the leading edge curve L and the blade pot and the blade back as P ₁ and P ₂ respectively, and calculate the tangent lines L ₁ , L ₂ and the two points at P ₁ and P ₂ The intersection of tangents O(O _x ,O _y );

The equation of the circle where the leading edge curve is located is: (xx ₀ ) ² +(yy ₀ ) ² =r ² where the center of the circle is (x ₀ ,y ₀ ) and the radius is r; the slope of any point on the calculated curve is k _i =( x _i -x ₀ )/(y _i -y ₀ ), where (xi _, y _i ) is any point on the curve, then the tangent equation of any point (xi _, y _i ) on the curve: y=y _i + _ki (xx _i );

The tangent line L ₁ at this point obtained from the slope k ₁ at P ₁ is respectively y=y ₁ +k ₁ (xx ₁ ), and the tangent line L ₂ at the two points obtained from the slope k ₂ at P ₂ is respectively y=y ₂ +k ₂ (xx ₂ ); then the coordinates of the intersection point O(O _x ,O _y ) of the two tangents are $(\frac{{\mathrm{the\; y}}_2-k_2{x}_2-{\mathrm{the\; y}}_1+k_1{x}_1}{k_1-k_2},\frac{k_1{k}_2(x_1-x_2)}{k_1-k_2}).$

求出角平分线的切线斜率k，则角平分线为y₃=O_y+k(x₃-O_x)；Step 3. Calculate the angle bisector L ₃ of the angle formed by the two tangents in step 2: use the formula

Find the tangent slope k of the angle bisector, then the angle bisector is y ₃ =O _y +k(x ₃ -O _x );

Step 4. Calculate the intersection point of the angle bisector L ₃ and the leading edge curve L in step 3, which is the leading edge point P ₀ of the arc-shaped leading edge;

Step 5. Set the process margin δ=0.15mm, take the leading edge point P ₀ as the reference, and along the direction of P ₀ O, find a straight line L ₄ with a distance of δ from point P ₀ ;

首先在L₃上找圆心M(m_x,m_y)到L₁、L₂、L₄的距离相等；并求出该距离d_m，作为相切圆M的半径；切点分别记为T₁、T₂、T₃,截取相应的圆弧段，并光滑连结线段T₁P₁、T₂P₂及圆弧T₁T₂，曲线段P₁T₃P₂即为航空叶片圆弧形前缘工艺模型。Step 6. Find the circle tangent to L ₁ , L ₂ , and L ₄ at the same time: use the distance formula from the point (x _m ,y _m ) to the straight line Ax+By+C=0

First find the distance from the center of circle M(m _x ,m _y ) to L ₁ , L ₂ , and L ₄ on L ₃ to be equal; and find the distance d _m as the radius of the tangent circle M; the tangent points are respectively recorded as T ₁ , T ₂ , T ₃ , intercept the corresponding arc segment, and smoothly connect the line segment T ₁ P ₁ , T ₂ P ₂ and arc T ₁ T ₂ , the curve segment P ₁ T ₃ P ₂ is the aviation blade arc Shaped leading edge process model.

The process model of the arc-shaped leading edge of the selected section of the blade generated through the above steps is shown in Figure 3. Among them, the circle where the arc segment T ₁ T ₂ of the leading edge process model is located is (x-32.88) ² +(y+3.32) ² =0.27 ² , and T ₁ (32.93,-3.59), T ₂ (32.87,- 3.05).

To sum up, in the engineering application of the method of the present invention, by importing the CAD model and setting the process error, the processing technology model of the aeronautical blade can be generated, and then the processing of the aeronautical blade can be guided, and the front and rear edges of the aeronautical blade can be effectively avoided. The overcut problem that may occur at the place, so as to ensure the processing quality of aviation blades.

Claims (1)

1. aerial blade circular arc front and rear edge process modeling generation method is characterized in that comprising the following steps:

Step 1, read in the aerial blade cad model;

Step 2, along vertical Z to intercepting aerial blade a certain cross section, leading edge curve L and leaf basin, blade back point of contact is designated as respectively P ₁, P ₂, ask P ₁, P ₂The tangent line L of place ₁, L ₂And the intersection point O (O of two tangent lines _x, O _y);

The leading edge Curves at the equation of circle is: (x-x ₀) ²+ (y-y ₀) ²=r ²Wherein, the center of circle is (x ₀, y ₀), radius is r; On calculated curve, the slope of any point is k _i=(x _i-x ₀)/(y _i-y ₀), (x wherein _i, y _i) be any point on curve, any point (x on curve _i, y _i) tangential equation: y=y _i+ k _i(x-x _i);

By P ₁The slope k at place ₁Try to achieve the tangent line L at this some place ₁Be respectively y=y ₁+ k ₁(x-x ₁), by P ₂The slope k at place ₂Try to achieve 2 tangent line L that locate ₂Be respectively y=y ₂+ k ₂(x-x ₂); Intersection point O (the O of two tangent lines _x, O _y) coordinate be $(\frac{y_2-k_2{x}_2-y_1+k_1{x}_1}{k_1-k_2},\frac{k_1{k}_2(x_1-x_2)}{k_1-k_2});$

The angular bisector L of two tangent line angles in step 3, calculation procedure two ₃, utilize formula

Obtain the tangent slope k of angular bisector, angular bisector is y ₃=O _y+ k (x ₃-O _x);

Angular bisector L in step 4, calculation procedure three ₃With the intersection point of leading edge curve L, be the leading edge point P of circular arc front edge ₀

Step 5, setting process allowance δ are with leading edge point P ₀Be benchmark, along P ₀The direction of O is asked a P ₀Distance be that the straight line of δ is made L ₄

Step 6, obtain and L ₁, L ₂, L ₄Simultaneously tangent circle utilizes point (x _m, y _m) to the range formula of straight line Ax+By+C=0 At first at L ₃On look for center of circle M (m _x, m _y) to L ₁, L ₂, L ₄Distance equate; And obtain this apart from d _m, as the radius of tangent circle M; The point of contact is designated as respectively T ₁, T ₂, T ₃, intercept corresponding arc section, and smooth link line segment T ₁P ₁, T ₂P ₂And circular arc T ₁T ₂, segment of curve P ₁T ₃P ₂Be aerial blade circular arc front edge process modeling.

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