阅读说明：本技术 一种叶片型面进排气边缘分段拟合评价的方法 (Method for evaluating sectional fitting of air inlet and outlet edges of blade profile ) 是由 田家龙 李深亮 田洪伟 史文斌 张绍东 于 2021-09-08 设计创作，主要内容包括：本发明公开一种叶片型面进排气边缘分段拟合评价的方法,该方法首先将测量得到的叶片型面数据选取横截面进行整体拟合,再将叶片分为叶盆、叶背、进气边缘和排气边缘四个部分,对拟合效果差的进气边缘和排气边缘进行限制条件下的二次拟合,最后计算拟合数据偏离出公差带的总长度值占截面全长的比例,做为叶片型面测量数据输出。本发明针对现有叶片测量分析软件存在的缺陷,更加准确合理的评价叶片型面进排气边缘的轮廓形状和数据指标,减少叶片型面测量分析过程中的误判,提高叶片的合格率。(The invention discloses a method for evaluating the sectional fitting of an air inlet and outlet edge of a blade profile, which comprises the steps of firstly selecting a cross section from measured blade profile data to perform integral fitting, then dividing a blade into a blade basin, a blade back, an air inlet edge and an air outlet edge, performing secondary fitting on the air inlet edge and the air outlet edge with poor fitting effect under a limiting condition, and finally calculating the proportion of the total length value of fitting data deviating from a tolerance zone to the total length of the section to be output as blade profile measurement data. Aiming at the defects of the existing blade measurement and analysis software, the invention more accurately and reasonably evaluates the profile shape and the data index of the air inlet and outlet edges of the blade profile, reduces the misjudgment in the blade profile measurement and analysis process and improves the qualification rate of the blade.)

1. A method for evaluating the sectional fitting of an air inlet edge and an air outlet edge of a blade profile is characterized by comprising the following steps:

step 1: measuring by using a three-coordinate measuring machine or a white light measuring machine to obtain measured data of the blade profile;

step 2: selecting actual measurement data and theoretical data of a certain cross section of the blade profile, and performing overall fitting on the cross section contour line by adopting a least square method;

and step 3: respectively selecting two points, namely 4 points in total, at the positions of the air inlet edge and the air outlet edge of the blade and the distance S from the vertex as theoretical segmentation points of the air inlet edge and the air outlet edge of the blade, and dividing the whole blade into a blade basin, a blade back, an air inlet edge and an air outlet edge;

and 4, step 4: reading out the maximum value of the leaf basin, the minimum value of the leaf basin, the maximum value of the leaf back, the minimum value of the leaf back, the position deviation value of the leaf profile and the torsion angle value of the leaf profile after the integral fitting in the step 2;

and 5: calculating theoretical data of a central line of a tolerance zone of the positions of the air inlet edge and the air outlet edge of the blade according to the theoretical data and the tolerance zone of the positions of the air inlet edge and the air outlet edge of the blade;

step 6: respectively carrying out least square fitting calculation on the molded lines of the air inlet edge and the air outlet edge of the blade subjected to integral fitting in the step 2 and theoretical data of a central line of a tolerance zone under a limiting condition, and reading out the maximum value of the air inlet edge, the minimum value of the air inlet edge, the maximum value of the air outlet edge and the minimum value of the air outlet edge;

and 7: calculating the sum of the lengths of the molded lines of the cross sections of the blades which deviate from the tolerance zone after the fitting in the steps 2 and 6, namely calculating the total length value of the deviation of the fitting data of the whole cross section from the tolerance zone;

and 8: calculating a proportion value of the total length of the fitting data deviated from the tolerance zone to the total length of the section, and outputting the proportion value as blade profile measurement data;

and step 9: and comparing the proportion value of the total length of the maximum blade basin value, the minimum blade basin value, the maximum blade back value, the minimum blade back value, the position deviation value of the blade profile, the torsion angle value of the blade profile, the maximum air inlet edge value, the minimum air inlet edge value, the maximum air outlet edge value, the minimum air outlet edge value and the deviation tolerance zone to the total length of the section with respective threshold values of precision requirements, and judging whether the blade profile meets the precision requirements.

2. The method of blade profile inlet and outlet edge piecewise fitting evaluation according to claim 1, wherein: the limiting condition in the step 6 is that the molded lines of the inlet edge and the exhaust edge of the blade perform position translation in the X direction and the Y direction, and are not allowed to rotate.

3. The method of blade profile inlet and outlet edge piecewise fitting evaluation according to claim 1, wherein: the density of the measured data of the blade profile at the molded line real measuring points of the air inlet edge and the air outlet edge is selected according to the following principle:

the density of actual measuring points within 1mm from the air inlet edge and the exhaust edge of the blade is 2-3 times that of other parts.

Technical Field

The invention relates to the technical field of measurement and analysis of compressor blades, in particular to a method for evaluating the sectional fitting of an air inlet and outlet edge of a blade profile.

Background

The measurement and analysis techniques of the blade are key techniques in the manufacturing process of the blade. According to the comparison of the section data points measured by the blades and theoretical data points, the section data corresponding to the processing program is found for optimization aiming at the deviation area, and the accuracy and the reasonability of the blade measurement result are the basis for the improvement of the blade process technology.

At present, the measurement precision of both a contact type three-coordinate measuring machine and a non-contact type measuring machine can meet the requirement of the blade. The blade profile data obtained by the measuring machine needs to be calculated by special blade analysis software so as to obtain the required elements of the design drawing. The analysis process of the prior aero-engine compressor blade has some problems which are mainly shown in the following steps:

1) the problem of inconsistent chord length tolerance and contour tolerance

Regarding the cross-sectional profile of the compressor blade, attention needs to be paid to the profile shape of the air inlet and outlet edge R, especially the profile shape of the air inlet edge R, so that the important aspect is shown in table 1 when designing the tolerance zone.

TABLE 1 parameters of tolerance, chord length and leading edge position of XX-XX stage stator blade edge profile

For blade sections that meet the leading edge and chord length dimension requirements, the edge profile also appears to be outside the tolerance band when fitted as a whole, and data reports show deviations from the tolerance profile.

2) The problem that the fitting of asymmetric tolerance is easy to be out of tolerance

Theoretical data is used as a fitting basis in the leaf profile fitting process, and even if the adopted edge segmentation fitting is adopted, the edge is not symmetrical in toleranceThe requirement on the roundness of the edge R is increased, the phenomenon of deviation under deviation of the edge profile is often caused, and the qualified section is judged as unqualified by mistake.

3) Problems of measuring the index

The white light measurement software and the three-coordinate measurement software do not have a statistical function, and the proportion of the molded line length deviating from a tolerance zone in the detection section of each blade to the total length of the section cannot be calculated.

Disclosure of Invention

In view of the defects of the prior art, the invention provides a method for evaluating the sectional fitting of the air inlet and outlet edges of the blade profile.

In order to solve the technical problems, the technical scheme adopted by the invention is as follows: a method for evaluating the sectional fitting of the air inlet and outlet edges of a blade profile comprises the following steps:

step 1: measuring by using a three-coordinate measuring machine or a white light measuring machine to obtain measured data of the blade profile;

step 2: selecting actual measurement data of a certain cross section of the blade profile and theoretical data given by a design file, and performing overall fitting on the contour line of the cross section by adopting a least square method;

and step 3: respectively selecting two points, namely 4 points in total, at the positions of the air inlet edge and the air outlet edge of the blade and the distance S from the vertex as theoretical segmentation points of the air inlet edge and the air outlet edge of the blade, and dividing the whole blade into a blade basin, a blade back, an air inlet edge and an air outlet edge; usually, the point position is given by a design file, and the value of S is 3-5 mm.

And 4, step 4: reading out the maximum value of the leaf basin, the minimum value of the leaf basin, the maximum value of the leaf back, the minimum value of the leaf back, the position deviation value of the leaf profile and the torsion angle value of the leaf profile after the integral fitting in the step 2;

and 5: calculating theoretical data of a central line of a tolerance zone of the positions of the air inlet edge and the air outlet edge of the blade according to theoretical data and the tolerance zone of the positions of the air inlet edge and the air outlet edge of the blade given by a design file;

step 6: respectively carrying out least square fitting calculation on the molded lines of the air inlet edge and the air outlet edge of the blade subjected to integral fitting in the step 2 and theoretical data of a central line of a tolerance zone under a limiting condition, and reading out the maximum value of the air inlet edge, the minimum value of the air inlet edge, the maximum value of the air outlet edge and the minimum value of the air outlet edge;

and 7: calculating the sum of the lengths of the molded lines of the cross sections of the blades which deviate from the tolerance zone after the fitting in the steps 2 and 6, namely calculating the total length value of the deviation of the fitting data of the whole cross section from the tolerance zone;

and 8: calculating the proportion of the total length value of the fitting data deviating from the tolerance zone to the total length of the section, and outputting the proportion as blade profile measurement data;

and step 9: and comparing the proportion value of the total length of the maximum blade basin value, the minimum blade basin value, the maximum blade back value, the minimum blade back value, the position deviation value of the blade profile, the torsion angle value of the blade profile, the maximum air inlet edge value, the minimum air inlet edge value, the maximum air outlet edge value, the minimum air outlet edge value and the deviation tolerance zone to the total length of the section with respective threshold values of precision requirements, and judging whether the blade profile meets the precision requirements.

Further, the density of the measured data of the blade profile at the profile line measured points of the air inlet edge and the air outlet edge is selected according to the following principle:

the density of actual measuring points within 1mm from the air inlet edge and the exhaust edge of the blade is 2-3 times that of other parts.

Further, the limitation condition in step 6 is that the molded lines of the inlet edge and the outlet edge of the blade perform position translation in the X direction and the Y direction, and are not allowed to rotate.

Adopt the produced beneficial effect of above-mentioned technical scheme to lie in:

the method provided by the invention combines the characteristics of the given technical indexes of the blade profile of the existing gas compressor, and carries out secondary segment fitting evaluation on the air inlet and outlet edges of the integrally fitted blade profile through theoretical data of a tolerance zone central line aiming at the defects of the existing blade measurement and analysis software, so that the profile shape and the data indexes of the air inlet and outlet edges of the blade profile are more accurately and reasonably evaluated, the misjudgment in the blade profile measurement and analysis process is reduced, and the qualification rate of the blade is improved.

Drawings

FIG. 1 is a flow chart of a method for evaluating a piecewise fitting of an inlet and outlet edge of a blade profile according to an embodiment of the present disclosure;

FIG. 2 is a diagram illustrating the overall fitting effect of the cross-sectional profile of the blade according to the embodiment of the present invention;

FIG. 3 is a diagram illustrating the overall fitting effect of the inlet edge of the blade according to the embodiment of the present invention;

FIG. 4 is a graph illustrating the overall fitting effect of the exhaust edge of the blade according to the embodiment of the present invention;

FIG. 5 is a diagram illustrating the quadratic fit effect of the inlet edge of the blade according to an embodiment of the present invention;

FIG. 6 is a graph of the effect of a second fit to the exhaust edge of a vane in an embodiment of the present invention;

wherein 1-theoretical data, 2-upper tolerance of tolerance band, 3-lower tolerance of tolerance band, 4-measured data.

Detailed Description

The following detailed description of embodiments of the present invention is provided in connection with the accompanying drawings and examples. The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.

As shown in fig. 1, the method for evaluating the piecewise fitting of the inlet and outlet edges of the blade type surface in this embodiment is as follows.

Step 1: measuring by using a three-coordinate measuring machine or a white light measuring machine to obtain measured data of the blade profile;

step 2: selecting measured data of a certain cross section of the blade profile and theoretical data given by a design file, and performing overall fitting on a cross section contour line by adopting a least square method, as shown in FIG. 2;

after the overall fitting, as can be seen from fig. 3 and 4, the overall fitting effect of the inlet edge and the exhaust edge of the blade is not ideal, and some measured data exceed the requirement of the upper tolerance.

And step 3: respectively selecting two points, namely 4 points in total, at the positions of the air inlet edge and the air outlet edge of the blade, which are away from the vertex by the distance S, as theoretical segmentation points of the air inlet edge and the air outlet edge of the blade, wherein the points are shown as 4 hollow circles in figure 2, and dividing the whole blade into a blade basin, a blade back, an air inlet edge and an air outlet edge; usually, the position of the point S is given by a design file, and is generally 3-5 mm.

And 4, step 4: reading out the maximum value of the leaf basin, the minimum value of the leaf basin, the maximum value of the leaf back, the minimum value of the leaf back, the position deviation value of the leaf profile and the torsion angle value of the leaf profile after the integral fitting in the step 2;

and 5: calculating theoretical data of a central line of a tolerance zone of the positions of the air inlet edge and the air outlet edge of the blade according to theoretical data and the tolerance zone of the positions of the air inlet edge and the air outlet edge of the blade given by a design file;

step 6: respectively carrying out least square fitting calculation on the molded lines of the air inlet edge and the air outlet edge of the blade subjected to integral fitting in the step 2 and theoretical data of a central line of a tolerance zone under a limiting condition, and reading out the maximum value of the air inlet edge, the minimum value of the air inlet edge, the maximum value of the air outlet edge and the minimum value of the air outlet edge;

after the quadratic fitting in step 6, as can be seen from fig. 5 and 6, the quadratic fitting effect of the inlet edge and the outlet edge of the blade is better than that of the overall fitting in step 2, and the data of the original fitting exceeding the upper tolerance are improved correspondingly.

And 7: calculating the sum of the lengths of the molded lines of the cross sections of the blades which deviate from the tolerance zone after the fitting in the steps 2 and 6, namely calculating the total length value of the deviation of the fitting data of the whole cross section from the tolerance zone;

and 8: calculating the proportion of the total length value of the fitting data deviating from the tolerance zone to the total length of the section, and outputting the proportion as blade profile measurement data;

and step 9: and comparing the proportion value of the total length of the maximum blade basin value, the minimum blade basin value, the maximum blade back value, the minimum blade back value, the position deviation value of the blade profile, the torsion angle value of the blade profile, the maximum air inlet edge value, the minimum air inlet edge value, the maximum air outlet edge value, the minimum air outlet edge value and the deviation tolerance zone to the total length of the section with respective threshold values of precision requirements, and judging whether the blade profile meets the precision requirements.

Further, the density of the measured data of the blade profile at the profile line measured points of the air inlet edge and the air outlet edge is selected according to the following principle:

the density of actual measuring points within 1mm from the air inlet edge and the exhaust edge of the blade is 2-3 times that of other parts.

Further, the limitation condition in step 6 is that the molded lines of the inlet edge and the outlet edge of the blade perform position translation in the X direction and the Y direction, and are not allowed to rotate.

In the embodiment, a section is selected from the section of the rotor blade at a certain stage, and the section is called a No. 5 section.

The maximum value of a blade basin is 0.06mm, the minimum value of the blade basin is-0.03 mm, the maximum value of a blade back is 0.03mm, the minimum value of the blade back is-0.05 mm, the position deviation value of a blade profile is 0.08mm, the torsion angle value of the blade profile is 0.15 degrees, the maximum value of an air inlet edge is 0.05mm, the minimum value of the air inlet edge is-0.02 mm, the maximum value of an air outlet edge is 0.07mm, and the minimum value of the air outlet edge is-0.05 mm. And calculating the sum of the lengths of the molded lines of the blade basin and the blade back deviated from the tolerance zone to be 1.2mm, and the sum of the lengths of the molded lines of the blade inlet and exhaust edges deviated from the tolerance zone to be 0.9mm, wherein the total length is 2.1 mm. The total length of the blade is 52.4mm, and the ratio of the length of the molded line deviating from the tolerance zone to the total length of the blade is 4%. The values obtained by the fitting were compared with the respective accuracy requirements as shown in table 2.

TABLE 25 comparison of Cross-section fitting values with accuracy requirements

In this embodiment, a section is also taken at a stator blade profile of a certain stage, which is called a # 8 section.

The maximum value of a blade basin is 0.08mm, the minimum value of the blade basin is-0.02 mm, the maximum value of a blade back is 0.04mm, the minimum value of the blade back is-0.06 mm, the position deviation value of the blade profile is 0.1mm, the torsion angle value of the blade profile is 0.10 degrees, the maximum value of an air inlet side is 0.06mm, the minimum value of an air outlet side is-0.02 mm, the maximum value of an air outlet side is 0.055mm, and the minimum value of the air outlet side is 0.02 mm. And calculating the sum of the lengths of the molded lines of the blade basin and the blade back deviated from the tolerance zone to be 3mm, and the sum of the lengths of the molded lines of the blade inlet and exhaust edges deviated from the tolerance zone to be 2.2mm, wherein the total length is 5.2 mm. The total length of the blade is 70.8mm, and the ratio of the length of the molded line deviating from the tolerance zone to the total length of the blade is 7.3 percent. The values obtained by the fitting were compared with the respective accuracy requirements as shown in table 3.

TABLE 38 comparison of Cross-section fitting values with accuracy requirements