High-precision repeated positioning method for repairing air film hole of part

Abstract

The invention relates to a high-precision repeated positioning method for part air film hole repairing, and effectively solves the problem that repairing, punching and positioning are difficult when obvious hole position difference exists between a service blade and a standard part. Before a blade is maintained, a zero-point positioning tool is used for clamping, and independent hole site data acquisition is performed on each maintenance piece and is saved as pre-acquired hole site parameters. And when the gas film holes are repaired, the zero-point positioning tool is used for clamping again, at least two small holes which are not blocked or shrunk before and after maintenance serve as anchoring holes, the positions of the anchoring holes are collected, the pre-collected hole positions and the anchoring hole positions are compared, and high-precision geometric positions of the blocked holes and the shrunk holes are obtained through difference calculation. Compared with an existing method based on standard parts, the method has the advantage of product self-calibration, product differences caused by different production batches and different manufacturers in an existing small hole positioning method can be overcome, and the positioning error of a traditional method can be reduced to be within + / -0.01 mm from + / -0.3 mm.

Description

TECHNICAL FIELD

[0001] The present application relates to a high-precision repeated positioning method for repairing air film holes of parts, and belongs to the field of machining of aero-engine parts, in particular, to high-precision repeated positioning of hole coordinates in the process of repairing air film holes of hollow turbine blades. BACKGROUND

[0002] When the aero-engine is working, as one of the hot end components, the hollow blade such as high-pressure turbine bears the impact of high-temperature and high-pressure gas. Under the premise that the high-temperature resistance of alloy material is limited, in order to improve the turbine inlet temperature and ensure the normal and reliable operation and work of the turbine in the high-temperature service environment, the hollow blade cooling technology of high-pressure turbine has become an effective way to solve this problem. The air film cooling hole can enable the high-pressure turbine hollow blade of the same material to operate normally in a higher temperature environment.

[0003] The hollow blade air film hole has a significant effect on the performance of the engine. Therefore, improving the processing capacity and efficiency of the blade air film hole has become one of the important research contents in the field of aero-engine. The air film cooling efficiency is very sensitive to the shape and position of the air film hole. Therefore, the geometric parameters such as the hole type and the position precision of the small hole are very important to ensure the processing quality. In the actual maintenance process, the orifice is often blocked by foreign matter, covering and other situations, which makes it difficult to position the small hole, and cross-hole, overlapping hole and other unqualified situations are easily caused, resulting in the scrap of the repaired blade and greatly reducing the yield of the repaired parts.

[0004] For the repaired parts of the high-pressure turbine hollow blade, the "standard part comparison" method is often used, which has the following disadvantages:

[0005] (1) The repaired blade has service deformation and single-piece machining hole position error, and there is a significant difference in hole position between the actual repaired part and the standard part.

[0006] (2) The blade air film hole is mostly inclined hole, and the hole axis positioning error further increases the normal positioning error.

[0007] According to the test verification: when the standard part is used for comparison processing, the hole position error of the small hole can reach more than twice the diameter of the small hole.

[0008] The Chinese patent CN215394849U (publication date: 2022.01.04) discloses an aero-engine blade film hole position and diameter positioning detection device. The device includes a base, a sliding mechanism, a turnover mechanism, a fixing mechanism, and an imaging mechanism. The moving workbench of the sliding mechanism is arranged in the sliding groove. The upper surface of the moving workbench is provided with a translation plate that can slide left and right. The turnover mechanism is fixedly arranged on the translation plate. The fixing mechanism is fixedly arranged on the turntable of the turnover mechanism. The upper surface of the fixing disc of the fixing mechanism is provided with a plurality of fixing pins for fixing the blade. The inner side of the fixing ring is provided with a plurality of fixing rods for strengthening the fixation. The imaging mechanism includes a lifting table and an industrial camera located at the lower part of the lifting table. By using a non-contact measurement method, the shooting accuracy is improved. At the same time, the blade is fixed by using a fixing device. The sliding mechanism and the turnover mechanism are used to effectively adjust the spatial placement position of the blade, thereby avoiding the influence of equipment angle positioning error on the diameter and position calibration of the film hole.

[0009] The Chinese patent CN217571887U (publication date: 2022.10.14) discloses an aero turbine blade film hole processing positioning device. The positioning device includes a base, two adjusting devices assembled on the base and symmetrically arranged on both sides of the base, and two limiting devices respectively assembled on the opposite sides of the adjusting devices and adjusted by the adjusting devices. The limiting device includes a fixing plate connected with the adjusting device and provided with a screw hole. One end of the fixing plate is provided with a spiral partition plate. The turbine blade is fixed by the two spiral partition plates. The patent adjusts the angle of the turbine blade through the limiting device, so that the turbine blade is in the best position during processing. The turbine blade can be automatically adjusted during processing, thereby avoiding the danger of the operator adjusting the turbine blade.

[0010] The Chinese patent CN113137627A (publication date: 2021.07.20) discloses a processing positioning method for aero-engine flame tube cooling film holes. The laser pre-dotting technology is used to pre-draw "black oxidation points" representing the film holes on the enhanced developer thin layer. The center point coordinates are obtained by processing the "black oxidation point" point cloud. The center point coordinates are fitted with the corresponding film hole design coordinates of the theoretical model. The spatial pose transformation algorithm is used for correction. After the spatial error correction, the coordinates of the pre-dotted film holes are input into the industrial computer. The center position of the pre-dotted film holes is tracked in real time. The accurate processing positioning of the film holes is realized. The patent has high positioning accuracy of the flame tube film holes. The problems of low geometric precision and unstable quality caused by accumulated deformation during the processing of the flame tube film holes are effectively solved.

[0011] Although the above patents solve some problems, they do not fundamentally solve the problem of difficult repair and positioning of punching when there is a significant difference in hole position between the service blade and the standard part. SUMMARY

[0012] The purpose of the present application is to overcome the shortcomings of the prior art, provide a kind of high-precision repeated positioning method for repairing gas film hole of spare part, effectively solve the problem of difficult repair punching positioning when there is obvious hole position difference between serviceable blade and standard part. Before blade repair, using zero point positioning tool clamping, collecting hole position data of each repair part separately, and saving as pre-acquired hole position parameters. When repairing gas film hole, use zero point positioning tool clamping again, use at least two small holes that do not appear to be blocked and shrunk before and after repair as anchor holes, collect anchor hole position, compare pre-acquired hole position and anchor hole position, and use difference to obtain high-precision blocked and shrunk small hole geometric position.

[0013] The present application is realized by the following technical solutions:

[0014] A kind of high-precision repeated positioning method for repairing gas film hole of spare part, comprising the following steps:

[0015] Step 1: spare part gas film hole partition

[0016] For high-pressure turbine blade or high-pressure guide vane blade that needs to be repaired for gas film hole, based on product design drawings, partition the gas film hole, small holes with parallel hole axis direction can be divided into the same group, that is, when clamped on the five-axis platform, small holes with equal A, C axis geometric parameters can be divided into the same group. For example, high-pressure turbine blade inlet edge longitudinal column small holes are divided into 1 group per column, and high-pressure guide vane blade inlet edge radial small holes are divided into 1 group per column.

[0017] Step 2: first acquisition of gas film hole geometric parameters

[0018] After exposing the gas film hole in the fluorine cleaning or pickling step, before the welding or coating process that may cause the hole to be blocked, use the zero point positioning tool to clamp, and install the tool on the five-axis platform. According to the A, C two-axis parameters determined by the design drawing, adjust the five-axis platform, so that the small hole to be collected is clearly visible in the image collected by the side-axis CCD, and the center of the small hole axis direction is coincided with the center point of the side-axis CCD target. Record the X, Y, Z three-axis coordinates of the small holes in the group in turn, and save (Xn, Yn, Zn) as data list 1. In addition, save the A, C axis coordinates of the small holes in the group and the number of the zero point positioning tool clamp used;

[0019] Step 3: check before repeated positioning

[0020] Visually check the tool clamping end face and the macroscopic geometric shape of the blade to be repaired to confirm that there is no deformation;

[0021] Step 4: acquisition of gas film hole reference point geometric parameters

[0022] The blade to be repaired is clamped using the same zero positioning tool as the first collection, and is installed on a five-axis platform. The A and C axis coordinate parameters are adjusted to the A and C axis coordinates of the group of film holes recorded during the first collection. The X, Y and Z three-axis coordinates are adjusted to the orifice positions of the film holes that are not blocked in the group of film holes (hereinafter referred to as anchor holes). The two film hole positions with the farthest physical distance in all anchor holes in the group are recorded, and are saved as anchor hole (Xn', Yn', Zn') output as data list 2.

[0023] Step 5: Film hole repair positioning coordinate calculation

[0024] The two film holes saved in Table 2 are compared. First, the data is reduced to the xy plane by removing the A, C and Z three-axis data. Second, the X and Y coordinate parameter differences of each anchor hole in Table 2 and Table 1 are calculated respectively, and the differences are used to calibrate the data set of the blocked hole parameters in Table 1:

[0025] (1) When the absolute value of the coordinate difference of each point is less than 0.002 mm, the mean value of the coordinate difference is used to correct the positioning of each small hole in Table 1;

[0026] (2) When the absolute value of the coordinate difference of each point in the X or Y direction is greater than 0.002 mm, first, the coordinate of any anchor hole is used to correct the small hole position to be processed for the first time, and then the hole position is corrected for the second time using rotation and translation.

[0027] Step 6: Add the X and Y coordinates of the repaired hole calculated and output to the A, C and Zn three-axis coordinates in data list 1 to generate a five-axis parameter file for small hole positioning of the processing equipment. Read from the processing equipment, and then measure the height of each small hole to obtain high-precision repeated positioning coordinates for film hole repair.

[0028] The present application has the following advantages: compared with the current method based on standard parts, the present application has the characteristics of product self-calibration, can overcome the product differences caused by different production batches and different manufacturers in the current small hole positioning method, and can reduce the positioning error of the traditional method from ±0.3 mm to within ±0.01 mm. BRIEF DESCRIPTION OF DRAWINGS

[0029] Fig. 1 Workflow schematic diagram;

[0030] Fig. 2 Pre-collection hole position and anchor hole position comparison schematic diagram;

[0031] Fig. 3 Comparison schematic diagram of the positioning method and the sample positioning method. DETAILED DESCRIPTION

[0032] The following will be described in conjunction with the accompanying Figs. 1-3Further detailed description of the technical solutions of the present application, but the protection scope of the present application is not limited to the following described products.

[0033] The present application takes the high-pressure turbine working blade (hereinafter referred to as: high-turbine blade) of an aero-engine as an example to describe the technical solutions in detail. The type of blade needs to re-repair the film hole during the maintenance process, so as to restore the cooling function and performance. In this process, the positioning accuracy of the film hole is a key indicator, and the high-precision repeated positioning implementation method is as follows:

[0034] Step 1: Analyze the drawings of the high-turbine blade, and group the geometric orientations of the small holes at the tip to be repaired;

[0035] Step 2: Receive the parts to be repaired, and use the zero-point positioning tool to clamp each part, then use the machining system with five axes to collect the hole positions of the small holes to be machined. The A and C axis parameters of the collection process are determined by the drawings, and the remaining small hole axial positioning parameters are collected, and the small hole parameter table 1 is output by piece.

[0036] Step 3: After the intermediate step of repairing the blade, the high-turbine blade is checked again to confirm that there is no macroscopic deformation.

[0037] Step 4: Use the same zero-point positioning tool as the previous step to clamp the blade again, and then use the same machining system with five axes and the same positioning collection method to collect the hole positions of the blade anchor holes, and then output the small hole parameter table 2.

[0038] Step 5: Compare the small hole parameter table 1 and the small hole parameter table 2 as shown in Fig. 2 The farthest No. 1 and No. 7 small holes are selected to correct the hole positions of the No. 5 and No. 8 small holes to be machined.

[0039] Step 6: The calculated coordinates generate a small hole positioning parameter file, which is read by the machining platform. The machining platform processes the blade according to the positioning file, and the local appearance of the machined blade is shown in Fig. 3 .

[0040] The above described is only a typical embodiment of the present application, it should be understood that the present application is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the concept described herein, by the above-mentioned teaching or related art or knowledge. The modifications and changes made by those skilled in the art without departing from the spirit and scope of the present application shall be within the scope of protection of the appended claims of the present application.

Claims

1. A high-precision repeatable positioning method for repairing air film holes in components, characterized by: Comprising the following steps: Step 1: Part film hole partition For high-pressure turbine blades or high-pressure guide vanes that need to be repaired, based on product design drawings, the film holes are partitioned, and small holes with parallel hole axis direction are divided into the same group, that is, when clamped on the five-axis platform, small holes with equal A and C axis parameters are divided into the same group; Step 2: Film hole geometric parameter first acquisition After exposing the film hole, before the process that may cause the hole to be blocked, use the zero positioning tool to clamp the part that needs to be repaired, and install the tool on the five-axis platform. According to the A and C axis parameters determined by the design drawings, adjust the five-axis platform so that the small holes to be collected are clearly visible on the image collected by the side-axis CCD, and the center of the small hole axis direction is coincident with the center point of the side-axis CCD target. Record the X, Y, Z three-axis coordinates of the group of small holes in turn, and save (Xn, Yn, Zn) as data list 1. In addition, save the A, C axis coordinates of the group of small holes and the number of the zero positioning tool used; Step 3: Check before repeated positioning Visually check the clamping end face of the tool and the macroscopic geometric shape of the blade to confirm that there is no deformation; Step 4: Film hole reference point geometric parameter acquisition Use the same zero positioning tool as the first acquisition to clamp the repaired blade, and install it on the five-axis platform. Adjust the A and C axis coordinates to the A and C axis coordinates of the group of film holes recorded in the first acquisition, and adjust the X, Y, Z three-axis coordinates to the hole position of the anchor hole that is not blocked in the group of film holes. Record the two farthest film hole positions in all anchor holes, and save them as anchor hole (Xn', Yn', Zn') output as data list 2; Step 5: Film hole repair positioning coordinate calculation Compare and calculate the two film holes saved in Table 2. First, reduce the dimension of the data to the xy plane by removing the A, C, and Z three-axis data. Second, calculate the X and Y coordinate parameter difference of each anchor hole in Table 2 and the corresponding Table 1, and use the difference to calibrate the data group in Table 1: (1) When the absolute value of the coordinate difference of each point is less than 0.002 mm, use the average value of the coordinate difference to correct the positioning of each small hole in Table 1; (2) When the absolute value of the coordinate difference of each point in X or Y direction is greater than 0.002 mm, first use the coordinate of any anchor hole to correct the small hole position for the first time, and then use rotation and translation to correct the hole position for the second time; Step 6: Add the X, Y coordinates of the calculated repair hole to the corresponding A, C, Zn three-axis coordinates in data list 1 to generate the five-axis parameter file for machining small holes. Read from the machining equipment, and then measure the height of each small hole to obtain the high-precision repeated positioning coordinates for film hole repair.

2. The high-precision repeated positioning method for repairing the gas film hole of a component according to claim 1, characterized in that: In step 1, the high-pressure turbine blade inlet edge longitudinal column small holes are divided into 1 group, and the high-pressure guide vane inlet edge radial small holes are divided into 1 group.

3. The high-precision repeated positioning method for repairing the gas film hole of a component according to claim 1, characterized in that: The parts that need to repair the air film hole are clamped by the zero positioning tool after the air film hole is exposed in the fluorine cleaning or pickling step and before the welding or coating process that may cause the hole to be blocked.

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