CN112395790B - Reservation method for side milling finish machining allowance of thin-wall blade - Google Patents

Abstract

The invention discloses a reservation method of a side milling finish machining allowance of a thin-wall blade, which comprises the following steps: step1: dividing the equal parameter finite element of the thin-wall blade; step2: establishing a section rigidity undetermined index epsilon of the thin-wall blade _j The method comprises the steps of carrying out a first treatment on the surface of the Step3: establishing the deformation u of the blade tip node at each isoparametric line _j And cross-section rigidity undetermined measurement index epsilon _j Is a unitary nonlinear regression equation mu _j The method comprises the steps of carrying out a first treatment on the surface of the Step4: setting a blade tip finish machining allowance range and a blade root finish machining allowance range; step5: selecting a plurality of blade tip finish machining cutting residual values and blade root finish machining cutting residual values, and substituting the blade tip finish machining cutting residual values and the blade root finish machining cutting residual values into a residual function in Step 3; step6: obtaining a functional expression of the blade tip finish machining allowance, the blade root finish machining allowance and geometric characteristics; step7: and carrying out non-uniform reservation on the blade tip and blade root curves b (u, v) of the thin-wall blade to obtain a blade tip and blade root driving curve b' (u, v) before finish machining. The method realizes non-uniform reservation of the finish machining allowance, so that the thin-wall blade is small in deformation, and machining errors are reduced.

Description

A Method for Reserving Finishing Allowance in Side Milling of Thin-walled Blades

technical field

The invention belongs to the technical field of thin-walled blade processing, and in particular relates to a method for reserving a finishing allowance for side milling of a thin-walled blade.

Background technique

Thin-walled blade parts such as turbines and impellers are the core of turbomachinery, and their manufacturing level directly affects the energy conversion efficiency of the overall engine. In order to pursue aerodynamic performance, the surface of impeller blades is often designed as a complex curved surface with large twist and high geometric precision, which puts forward higher requirements for manufacturing precision.

Some ruled surface blades can use side milling to achieve high-efficiency wide-row cutting. In the actual cutting process, due to the large axial depth of cut, the large milling force generated by side milling causes elastic deformation of thin-walled blades during processing. Resulting in poor machining accuracy of the blade. In order to reduce the adverse effects of machining deformation in the process of CNC machining, the strategies and methods often used are: optimizing cutting parameters to reduce cutting force to obtain smaller blade deformation, and constant force cutting strategy to reduce chatter to obtain better blade deformation. Good surface quality, residual errors are corrected by quadratic error compensation.

The above strategy to reduce machining deformation error requires additional operations to obtain empirical data, lacks operating specifications and is difficult to guarantee machining efficiency. However, reducing machining errors by enhancing blade process stiffness and suppressing blade deformation is more efficient and relatively simple to operate. The uniform margin reservation method is simple to operate, but the reserved uniform margin will cause large differences in the deformation of the blades at different thicknesses and heights, resulting in shortcomings such as rough blade surfaces and uneven blade error trends. Error trimming.

Contents of the invention

In order to solve the above problems, the object of the present invention is to provide a thin-walled blade side milling finishing allowance reservation method, the method realizes the non-uniform reservation of the finishing allowance, so that the thin-walled blade has small deformation and reduces machining error.

To achieve the above object, the technical solution of the present invention is:

A method for reserving a finishing allowance in side milling of a thin-walled blade, comprising:

Step1: Use the finite element method to analyze the deformation of the thin-walled blade, divide the thin-walled blade with equal parameter finite element elements, and form j equal-parameter cross-sections along the V direction of the thin-walled blade and form along the V direction of the blade surface j isoparms, apply a side milling milling force at each of the isoparms, and obtain the deformation u _j of the blade tip node at each of the isoparms under the action of the milling force; and define the U direction as along The axial direction and the V direction of the thin-walled blade are along the tangential direction of the thin-walled blade;

Step2: establish the undetermined measure index ε _j of the section stiffness of the thin-walled blade, and Definition The larger the ε _j is, the easier the section of the thin-walled blade is to deform;

Wherein, _hj is the height of the thin-walled blade, _tj is the average thickness of the section of the thin-walled blade, m and n are the undetermined measurement coefficients of the undetermined measurement index ε _j of the section stiffness, m and n are integers and m>0, n<0;

Step3: Establish a unary nonlinear regression equation of the deformation u _j of the blade tip node at each of the isoparms and the undetermined measure ε _j of the section stiffness: μ _j = b ₂ ·ε _j ² +b ₁ · ε _j +...+b ₀ ; establish the margin function of the blade tip finishing allowance Δ _1j , the blade root finishing allowance Δ _2j and the deformation u _j of the blade tip node of each isoparm:

Among them, b ₂ , b ₁ , b ₀ are the coefficients and constants of the nonlinear regression equation, and k ₁ , k ₂ , c ₁ , c ₂ are the coefficients and constants of the residual function;

Step4: Set the range of cutting allowance for blade tip finishing: [Δ _min , (Δ _min +Δ _max )/2], and the range of cutting allowance for blade root finishing: [(Δ _min +Δ _max )/2, Δ _max ];

Among them, Δ _min is the minimum value reserved for the actual finishing allowance before cutting, and Δ _max is the maximum value reserved for the actual finishing allowance before cutting;

Step5: According to the blade tip finishing cutting allowance range and the blade root finishing cutting allowance range described in Step4, select a number of the blade tip finishing cutting allowance values and the blade root finishing cutting allowance values , substitute into the margin function in Step3 to obtain k ₁ , k ₂ , c ₁ , c ₂ values;

Step6: Substituting the unary nonlinear regression equation in Step3 and the undetermined measure index _εj of section stiffness in Step2 into the margin function in Step3 to obtain the blade tip finish machining allowance, the The functional expression of blade root finishing allowance and geometric features:

Wherein, Δ ₁ is the cutting allowance function for the finishing of the blade tip, and Δ ₂ is the cutting allowance function for the finishing machining of the blade root;

Step7: According to the margin function calculated in Step6, the blade tip and blade root curve b(u, v) of the thin-walled blade is reserved non-uniformly, and the blade tip and blade root driving curve b before finishing is obtained '(u, v) is:

Among them, b _u is the U direction vector of the blade tip or blade root, and b _v is the V direction vector of the blade tip or blade root.

According to an embodiment of the present invention, in Step 1, the first leaf surface of the thin-walled blade and the second leaf surface opposite to the first leaf surface are all divided by equal-parameter finite element elements, wherein 21 lines are formed along the V-direction Line: j=1:1:21, take 5 points in U direction of each isoparametric line in V direction, i=1:1:5.

According to an embodiment of the present invention, the average thickness t _j of the thin-walled blade described in Step2 is calculated as the average value of the distances between the corresponding points at the two isoparms:

in, is the point of the first leaf surface of the thin-walled blade at the i-th position in the U direction and the j-th position in the V direction, /> is the point of the second blade surface of the thin-walled blade at the i-th position in the U direction and the j-th position in the V direction.

According to an embodiment of the present invention, in Step2, a number of values of m and n are combined to establish the deformation amount u _j of the blade tip node at each of the isoparms and any combination The nonlinear regression analysis of , if and only when the standard deviation of the nonlinear regression analysis is the smallest, the values of m and n are selected.

According to an embodiment of the present invention, in Step5, the value of the cutting allowance for the finishing of the blade tip is inversely proportional to the value of the undetermined measure index _εj of the section stiffness, and the value of the cutting allowance for the finishing of the blade root is inversely proportional to the value of the cutting allowance for the finishing of the blade root. The undetermined measure index ε _j value of the section stiffness is proportional to it.

Compared with the prior art, the present invention has the following advantages and positive effects due to the adoption of the above technical scheme:

(1) Through Step1-Step7 in the embodiment of the present invention, the margin before finishing machining is reserved, which can greatly enhance the process stiffness of the thin-walled blade during side milling, effectively suppress the deformation of the thin-walled blade during the side milling process, and can While ensuring efficiency, the best suppression of thin-walled blade deformation is achieved, and the processing quality of the thin-walled blade surface is improved.

(2) In the embodiment of the present invention, it is further defined in Step5 that the value of cutting allowance for blade tip finishing is inversely proportional to the undetermined measurement index εj value of section stiffness, and the value of cutting allowance for blade root finishing is inversely proportional to the undetermined measurement index for section stiffness. The value of εj is proportional, which makes the calculation result more accurate and makes the deformation of the thin-walled blade smaller.

Description of drawings

The specific embodiment of the present invention is described in further detail below in conjunction with accompanying drawing, wherein:

Fig. 1 is a thin-walled blade side milling finishing allowance reservation method for thin-walled blades and other parameters finite element division diagram of the present invention;

Fig. 2 is a thin-walled blade height and deformation result diagram of a thin-walled blade side milling finishing allowance reservation method according to the present invention;

Fig. 3 is a graph showing the average thickness and deformation results of a thin-walled blade according to the method for reserving the finishing allowance in side milling of the thin-walled blade according to the present invention;

Fig. 4 is a thin-walled blade side milling finishing allowance reservation method according to the present invention;

Fig. 5 is a thin-walled blade tip node deformation amount and deformation result diagram of a thin-walled blade side milling finishing allowance reservation method according to the present invention;

Fig. 6 is a kind of thin-walled blade side milling finishing allowance reservation method according to the present invention. The deformation of the tip node at the isoparameter of the thin-walled blade and the unitary nonlinear regression equation function diagram of the undetermined measurement index ε _j of the section stiffness ;

Fig. 7 is a margin function diagram of a thin-walled blade side milling finishing allowance reservation method of the present invention, the blade root finishing cutting allowance and the deformation of the blade tip node;

Fig. 8 is a driving curve of the blade tip and blade root before finishing according to a thin-walled blade side milling finishing allowance reservation method according to the present invention.

Explanation of reference signs:

1: tip; 2: root; 3: isoparm; 4: driving curve of tip; 5: driving curve of root; 6: first leaf surface of thin-walled blade; 7: second leaf of thin-walled blade noodle.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments. Advantages and features of the present invention will be apparent from the following description and claims. It should be noted that the drawings are all in a very simplified form and use imprecise ratios, which are only used to facilitate and clearly assist the purpose of illustrating the embodiments of the present invention.

It should be noted that all directional indications (such as up, down, left, right, front, back...) in the embodiments of the present invention are only used to explain the relationship between the components in a certain posture (as shown in the accompanying drawings). Relative positional relationship, movement conditions, etc., if the specific posture changes, the directional indication will also change accordingly.

Referring to Figures 1 to 8, the core of the present invention is to provide a thin-walled blade side milling finishing allowance reservation method, including the following steps:

Step1: Use the finite element method to analyze the deformation of thin-walled blades, divide the thin-walled blades into equal-parameter finite element, form j equal-parameter cross-sections along the V direction of the thin-walled blades and form j equal-parameter sections along the V direction of the blade surface Line 3, the side milling force is applied at each isoparametric line 3, and the deformation u _j of the blade tip 1 node at each isoparametric line 3 under the action of milling force is obtained; and the U direction is defined as along the thin-walled blade axial direction, The V direction is the tangential direction along the thin-walled blade;

Specifically, the thin-walled blade is subjected to finite element force deformation analysis by finite element analysis software.

Step2: establish the undetermined measure index ε _j of the section stiffness of the thin-walled blade, and Definition The larger the ε _j is, the easier the section of the thin-walled blade is to deform;

Wherein, _hj is the height of the thin-walled blade, _tj is the average thickness of the section of the thin-walled blade, m and n are the undetermined measurement coefficients of the undetermined measurement index ε _j of the section stiffness, m and n are integers and m>0, n<0;

The blade height is the section length of the isoparametric section, that is, the length of the isoparametric line 3 . The average thickness t _j of the thin-walled blade is calculated as the average value of the distances between the corresponding points at the two isoparms 3: where, /> is the point of the first blade surface 6 of the thin-walled blade at the i-th position from U and the j-th position from V, /> It is the point of the second blade surface 7 of the thin-walled blade at the i-th position in the U direction and the j-th position in the V direction.

Preferably, in order to make the values of m and n more reasonable, first try to combine several values of m and n, and establish the deformation amount u _j of node 1 of the blade tip at 3 positions of each isoparametric line and any combination The nonlinear regression analysis of , if and only when the standard deviation of the nonlinear regression analysis is the smallest, the values of m and n are selected.

Step3: Establish the unary nonlinear regression equation of the deformation u _j of the blade tip 1 node at the 3 positions of each isoparameter and the undetermined measure index ε _j of the section stiffness: μ _j = b ₂ ·ε _j ² +b ₁ ·ε _j +. ..+b ₀ ; establish the margin function of the blade tip 1 finish machining allowance Δ _1j , the blade root 2 finish machining allowance Δ _2j and the deformation u _j of the blade tip 1 node of each isoparm 3:

Among them, b ₂ , b ₁ , b ₀ are the coefficients and constants of the nonlinear regression equation, and k ₁ , k ₂ , c ₁ , c ₂ are the coefficients and constants of the residual function;

Step4: Set the cutting allowance range for finishing blade tip 1 to [Δ _min , (Δ _min +Δ _max )/2], and the range of cutting allowance for finishing machining at blade root 2: [(Δ _min +Δ _max )/ 2, _Δmax ];

Among them, Δ _min is the minimum value reserved for the actual finishing allowance before cutting, and Δ _max is the maximum value reserved for the actual finishing allowance before cutting;

Step5: According to the range of cutting allowance for finishing machining of blade tip 1 and the range of cutting allowance for finishing machining of blade root 2 in Step4, select a number of cutting allowance values for finishing machining of blade tip 1 and finishing machining of blade root 2, and substitute them in Step3 Residual function, obtain k ₁ , k ₂ , c ₁ , c ₂ values;

When selecting the value of cutting allowance for finishing machining of blade tip 1 and cutting allowance for finishing machining of blade root 2, the value of cutting allowance for finishing machining of blade tip 1 is inversely proportional to the value of the undetermined measurement index ε _j of section stiffness, and 2. The value of cutting allowance in finishing machining is proportional to the undetermined measure index ε _j value of section stiffness.

That is to say, when the value of the undetermined measurement index ε _j of the section stiffness is relatively large, the smaller value of the finishing cutting allowance of the blade tip 1 and the larger value of the finishing cutting allowance of the blade root 2 are taken; the undetermined measurement index of the section stiffness ε _j When the value is small, take the larger cutting allowance value for the finishing of blade tip 1 and the smaller value of cutting allowance for finishing machining of blade root 2.

Because the greater the value of the undetermined measurement index ε _j of section stiffness, the thinner blade is more likely to deform at this position, so it is necessary to take a smaller value of the blade tip 1 finish machining allowance and a larger blade root 2 finish machining allowance Relatively, the smaller the value of the undetermined section stiffness _εj value, it means that the deformation of the thin-walled blade at this position is less affected by the geometric parameters, and a larger cutting allowance value for finishing machining of the blade tip 1 and Smaller blade root 2 finish machining allowance value. When the value of the undetermined section stiffness _εj is the largest, take the blade tip 1 finishing allowance as the minimum value, and the blade root 2 finishing cutting allowance as the maximum value; when the section stiffness undetermined measurement index _εj value is the smallest, take The cutting allowance for finishing machining of blade tip 1 is the maximum value, and the cutting allowance for finishing machining of blade root 2 is the minimum value.

Step6: Substitute the unary nonlinear regression equation in Step3 and the undetermined measure index _εj of section stiffness in Step2 into the allowance function in Step3 to obtain the finishing cutting allowance of blade tip 1, the finishing cutting allowance of blade root 2 and Functional expressions for geometric features:

Wherein, Δ ₁ is the blade tip 1 finishing cutting allowance function, and Δ ₂ is the blade root 2 finishing cutting allowance function;

Step7: According to the margin function calculated in Step6, the blade tip 1 and blade root 2 curves b(u, v) of the thin-walled blade are non-uniformly reserved, and the blade tip driving curve 4 and blade root before finishing are obtained The driving curve 5b'(u, v) is:

Among them, b _u is the U direction vector of blade tip 1 or blade root 2, and b _v is the V direction vector of blade tip 1 or blade root 2.

A specific calculation example is given below:

In Step1, the first blade surface 6 of the thin-walled blade and the second blade surface opposite to the first blade surface are all subjected to equal-parameter finite element division, wherein 21 lines are formed along the V-direction division: j=1:1:21, Take 5 points in the U direction of each isoparm 3 in the V direction, i=1:1:5.

Calculate the height of thin-walled blades according to the division results, combined with the formula:

Calculate the average thickness of the thin-walled blade, and determine m=1, n=-1 according to the deformation distribution state of the blade tip 1 and the preferred embodiment of Step2, and the section stiffness is to be determined. Combining Fig. 4 and Fig. 5, when the section stiffness undetermined index ε _j is larger, the isoparametric section of the thin-walled blade is more likely to be deformed.

A one-variable nonlinear regression equation established according to the distribution state of the blade tip 1 node deformation μ _j at the position 3 of the 21 isoparameters and the undetermined measure ε _j of the section rigidity. When the order of the regression equation is 2 times, the obtained regression function The effect is the best, when the minimum standard deviation is 0.71%, the established one-variable nonlinear regression equation is: μ _j = (0.1009·ε _j ² +0.2492·ε _j +2.6176)·10 ^-3 , as shown in Figure 6 .

Set the allowable reserved range of finishing allowance according to the allowable range of allowance before finishing: 0.05-0.2mm: blade tip 1 finishing cutting allowance range: 0.05-0.12mm, blade root 2 finishing cutting allowance allowable Range: 0.13-0.2; according to the definition of the undetermined measure index of section stiffness, at the minimum point of ε _j = 5.1523, the stiffness index of the section of the thin-walled blade is better, and the deformation of the thin-walled blade is less affected by the structural characteristics of the blade. Therefore, The maximum allowable cutting allowance for finishing machining of blade tip 1 is 0.12 mm, and the minimum allowable cutting allowance for finishing machining of blade root 2 is 0.13 mm; at the largest thin-walled blade section where ε _j = 24.1790, the thin-walled blade deforms The structural characteristics of the blade are greatly affected, and the rigidity index here is poor. Therefore, the maximum allowable cutting allowance for finishing machining of blade root 2 is 0.2 mm, and the minimum allowable cutting allowance for finishing machining of blade tip 1 is 0.05 mm.

The margin function of the blade tip 1 finishing allowance Δ _1j , the blade root 2 finishing allowance Δ _2j and the deformation u _j of the blade tip 1 node of each isoparm 3 is established as follows:

The undetermined measure of the section stiffness is expressed as the geometric parameters of the thin-walled blade: ε=h ¹ t ^-1 , and the unary nonlinear regression equation is brought into the margin function, and the function shown in Figure 7 is obtained as:

The cutting allowance function for finishing the blade tip 1 is: Δ ₁ =-0.0001h ² a ^-2 +0.0003ha ^-1 +0.119.

The cutting allowance function for finishing machining of the blade root 2 is: Δ ₂ =0.0001h ² a ^-2 +0.00029ha ^-1 +0.131.

According to the calculated cutting allowance function of tip 1 finish machining and blade root 2 finish machining allowance function, the allowance at any V direction of the thin-walled blade is obtained, and the finishing cutting allowance of blade tip 1 and blade root 2 are calculated. The cutting allowance for finishing machining is reserved, and the blade tip 1 or blade root 2 curve b(u, v) on one side of the curved surface of the thin-walled blade is non-uniformly offset in the normal direction of the blade surface, as shown in Figure 8 Tip driving curve 4 and blade root driving curve 5 before finishing.

The present invention aims at the deficiencies of the existing side milling processing method, improves the margin reservation before finishing, and realizes the blade tip 1 and blade root 2 within the allowable range of the finishing margin according to the actual geometric characteristics of the thin-walled blade. The continuous non-uniform margin is reserved to achieve the best suppression effect on blade deformation and minimize the processing error caused by deformation.

Due to the geometric characteristics of thin-walled blades, the milling force generated during side milling is likely to cause elastic deformation of the thin-walled blades in the normal direction of the milling contact area. The parameters of the thin-walled blades are divided and the parameters of the blades are obtained by assigning radial milling forces. The deformation of the position, calculate the undetermined index of section stiffness at this position and establish the connection between the deformation of the tip 1 node and the undetermined index of section stiffness, on the basis of the above, use the definition of section stiffness to measure the undetermined index for the finished blade tip 1 and blade The non-uniform allowance is reserved according to the 2 allowance, and the functional equation of the reserved allowance and the geometric characteristic parameters of the thin-walled blade is obtained. According to this method, the margin after semi-finishing is calculated and reserved, which can greatly enhance the process rigidity during side milling of thin-walled blades, effectively suppress the deformation of thin-walled blades during side milling, and reduce deformation errors. The method can ensure the efficiency in the finishing process and at the same time realize the best suppression of blade deformation and improve the processing quality of the blade surface.

The embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the above embodiments. Even if various changes are made to the present invention, if these changes fall within the scope of the claims of the present invention and equivalent technologies, they still fall within the protection scope of the present invention.

Claims (5)

1. A thin-walled blade side milling finishing allowance reservation method, characterized in that, comprising: Step1: Use the finite element method to analyze the deformation of the thin-walled blade, divide the thin-walled blade with equal parameter finite element elements, and form j equal-parameter cross-sections along the V direction of the thin-walled blade and form along the V direction of the blade surface j isoparms, apply a side milling milling force at each of the isoparms, and obtain the deformation u _j of the blade tip node at each of the isoparms under the action of the milling force; and define the U direction as along The axial direction and the V direction of the thin-walled blade are along the tangential direction of the thin-walled blade; Step2: establish the undetermined measure index ε _j of the section stiffness of the thin-walled blade, and Definition The larger the ε _j is, the easier the section of the thin-walled blade is to deform; Wherein, _hj is the height of the thin-walled blade, _tj is the average thickness of the section of the thin-walled blade, m and n are the undetermined measurement coefficients of the undetermined measurement index ε _j of the section stiffness, m and n are integers and m>0, n<0; Step3: Establish a unary nonlinear regression equation of the deformation u _j of the blade tip node at each of the isoparms and the undetermined measure ε _j of the section stiffness: μ _j = b ₂ ·ε _j ² +b ₁ · ε _j +...+b ₀ ; establish the margin function of the blade tip finishing allowance Δ _1j , the blade root finishing allowance Δ _2j and the deformation u _j of the blade tip node of each isoparm: Among them, b ₂ , b ₁ , b ₀ are the coefficients and constants of the nonlinear regression equation, and k ₁ , k ₂ , c ₁ , c ₂ are the coefficients and constants of the residual function; Step4: Set the range of cutting allowance for blade tip finishing: [Δ _min , (Δ _min +Δ _max )/2], and the range of cutting allowance for blade root finishing: [(Δ _min +Δ _max )/2, Δ _max ]; Among them, Δ _min is the minimum value reserved for the actual finishing allowance before cutting, and Δ _max is the maximum value reserved for the actual finishing allowance before cutting; Step5: According to the blade tip finishing cutting allowance range and the blade root finishing cutting allowance range described in Step4, select a number of the blade tip finishing cutting allowance values and the blade root finishing cutting allowance values , substitute into the margin function in Step3 to obtain k ₁ , k ₂ , c ₁ , c ₂ values; Step6: Substituting the unary nonlinear regression equation in Step3 and the undetermined measure index _εj of section stiffness in Step2 into the margin function in Step3 to obtain the blade tip finish machining allowance, the The functional expression of blade root finishing allowance and geometric features: Wherein, Δ ₁ is the cutting allowance function for the finishing of the blade tip, and Δ ₂ is the cutting allowance function for the finishing machining of the blade root; Step7: According to the margin function calculated in Step6, the blade tip and blade root curve b(u, v) of the thin-walled blade is reserved non-uniformly, and the blade tip and blade root driving curve b before finishing is obtained '(u, v) is: Among them, b _u is the U direction vector of the blade tip or blade root, and b _v is the V direction vector of the blade tip or blade root. 2. The thin-walled blade side milling finishing allowance reservation method according to claim 1, characterized in that, in Step1, the first blade surface of the thin-walled blade and the second blade surface opposite to the first blade surface are The two leaf surfaces are divided by isoparametric finite element elements, in which 21 lines are formed along the V direction: j=1:1:21, and 5 points are taken in the U direction of each isoparametric line in the V direction, i=1:1 : 5. 3. The thin-walled blade side milling finishing allowance reservation method according to claim 1 is characterized in that, the average thickness _t of the thin-walled blade described in Step2 is calculated as the average of the distances at the corresponding points at the two isoparms value: in, is the point of the first leaf surface of the thin-walled blade at the i-th position in the U direction and the j-th position in the V direction, /> is the point of the second blade surface of the thin-walled blade at the i-th position in the U direction and the j-th position in the V direction. 4. The thin-walled blade side milling finishing allowance reservation method according to claim 1, characterized in that, in Step2, a number of m and n values are combined to establish blade tip nodes at each of the isoparms The deformation amount u _j in any combination with The nonlinear regression analysis of , if and only when the standard deviation of the nonlinear regression analysis is the smallest, the values of m and n are selected. 5. The thin-walled blade side milling finishing allowance reservation method according to claim 1, characterized in that, in Step5, the value of the blade tip finishing cutting allowance value and the undetermined measurement index ε of the section stiffness The value of _j is inversely proportional, and the value of the blade root finishing cutting allowance is directly proportional to the value of the undetermined measure index εj of the section stiffness.