A double-end turbine blade full-surface numerical control polishing processing method

Abstract

The application discloses a kind of double-end crown turbine blade full profile numerical control polishing processing method, according to the upper and lower edge plate design positioning point after blade casting determines design coordinate system PCS1, blade is fixed on 3R quick-change fixture tray;Three coordinate measuring machines are measured to turbine blade blade, obtain blade profile data, then in PCS1 coordinate system, corresponding measurement point data is positioned to blade positioning geometric element and is registered, and the best position of blade datum or coordinate system under the best state of blade profile excess is optimized, and it is recorded as PCS2;According to the space conversion relationship between PCS2 and PCS1, the upper and lower edge plate positioning point of blade is corrected, and the fine finishing positioning point is obtained;With fine finishing positioning point as positioning datum, turbine blade is carried out blade profile polishing correction and full profile numerical control polishing, and based on the fine finishing datum, the numerical control grinding processing of blade subsequent process blade crown and tenon is simultaneously completed.The application improves the numerical control polishing efficiency of cast blade, replaces artificial polishing.

Description

Technical Field

[0001] The present invention relates to the technical field of blade processing, in particular to a full-surface numerical control polishing processing method for a double-ended shrouded turbine blade. Background Art

[0002] Aircraft engine turbine blades are primarily formed through precision casting. The complex casting process results in varying blade profile deformation and inconsistent blade allowances. Currently, the solution for turbine blades (excluding the tenon) is precision casting combined with manual polishing. However, manual polishing is labor-intensive and labor-intensive. The large amount of dust generated during manual polishing seriously impacts operator health. Furthermore, the quality of blade polishing is determined by the operator's proficiency and skill. This leads to artificial fluctuations in key indicators such as profile accuracy and surface quality of in-service turbine blades, impacting the blade's performance and usability.

[0003] The current process flow of turbine blades: After the turbine blades are cast, they are positioned using the rough datum after casting, and the turbine blade body is measured using a measuring tool. After the measurement, any areas where the blade body contour is out of tolerance are corrected by manual grinding, and then the blade body is positioned using the hand-polished blade body, and the blade tenon and blade crown are ground (or for double-ended shrouded turbine blades, the rough datum measurement is continued for positioning to complete the grinding of the tenon and blade crown).

[0004] At present, this processing technology has the following disadvantages:

[0005] 1) After casting, the positioning reference used to measure the blade profile is a blank reference with low precision. It cannot accurately measure the true profile of the blade, which can easily lead to misjudgment of whether the blade is qualified or not;

[0006] 2) During the grinding of the tenon and blade crown, the accuracy of the blade body positioning datum depends on the two processes of hot casting and manual grinding, and the error fluctuation is large;

[0007] 3) There is no uniform benchmark available for array ground-polished cast blades. Summary of the Invention

[0008] In order to solve the above technical problems, a CNC polishing process for the full-surface of double-ended shrouded turbine blades is proposed. The specific technical solution is as follows:

[0009] A method for CNC polishing the entire surface of a double-ended shrouded turbine blade, comprising the following steps:

[0010] Step 1: Determine the design coordinate system PCS1 based on the design positioning points of the upper and lower edge plates after the blade is cast, and fix the blade on the 3R quick-change fixture pallet. The 3R quick-change fixture pallet is used to accurately position the blade during blade measurement and processing.

[0011] Step 2: Use a three-dimensional coordinate measuring machine to measure the turbine blade fixed on the 3R quick-change fixture tray to obtain the blade profile data. Then, in the PCS1 coordinate system, align the blade positioning geometric elements and the corresponding measurement point data to optimize the blade reference or the optimal position of the coordinate system under the optimal blade profile margin, which is recorded as PCS2.

[0012] Step 3: Based on the spatial conversion relationship between PCS2 and PCS1, perform CNC machining correction on the upper and lower edge plate design positioning points of the blade in step 1 to obtain the positioning points after refinement;

[0013] Step 4: Using the refined positioning point in step 3 as the positioning reference, perform blade body contour polishing correction and full-surface CNC polishing on the turbine blade, and simultaneously complete the CNC grinding of the blade crown and tenon for subsequent processes of the blade based on this positioning reference.

[0014] The preferred embodiment of the method for CNC polishing the full-surface of a double-ended shrouded turbine blade is as follows: in step 1, the design coordinate system PCS1 is determined by calculating the six-point positioning theory on the upper and lower edge plates of the blade.

[0015] The described method for CNC polishing the full-surface of a double-ended shrouded turbine blade has an optimal solution: in step 2, a three-coordinate contact measurement method is used for measuring the blade, and the described alignment and positioning process mainly comprises: taking the minimum sum of squares of all measurement points and corresponding theoretical points of the blade body under the premise of minimizing the area of ​​the blade body out of tolerance as the objective function, taking the lower profile tolerance of the blade as the constraint condition, establishing an alignment and positioning optimization mathematical model, and using a genetic algorithm to solve the alignment and positioning optimization mathematical model to obtain the spatial conversion relationship from PCS1 to PSC2.

[0016] The preferred embodiment of the method for CNC polishing the entire surface of a double-ended shrouded turbine blade is that, in step three, a CNC grinding method is used to correct the positioning points.

[0017] The preferred embodiment of the method for CNC polishing the entire surface of a double-ended shrouded turbine blade is that, in step four, the polishing tool used for CNC polishing the entire surface of the blade body is a super-hard abrasive complex generatrix flexible polishing wheel. Beneficial effects

[0018] 1) The process method of the present invention can effectively determine the unqualified area of ​​the blade body of the cast turbine blade, minimize the unqualified casting area, and provide a precise CNC machining positioning reference;

[0019] 2) This process ensures the uniformity of the processing benchmarks for the blade body, tenon, and edge plate, avoiding the influence of unstable errors in the hot casting and manual grinding processes;

[0020] 3) Cooperating with array processing machine tools can increase the production efficiency of batch blades exponentially. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the double-ended shrouded turbine blade structure;

[0022] Figure 2 Flow chart of the process of the present invention;

[0023] Figure 3 Schematic diagram of blade and body registration and positioning in an embodiment of the present invention.

[0024] In the figure, Y-blade body, G-blade crown, T-blade tenon. DETAILED DESCRIPTION

[0025] The following is combined with Figure 1-3 The present invention is further described in detail with reference to the accompanying drawings and examples. Example

[0026] Figure 1 It is a schematic diagram of the structure of a double-ended shrouded turbine blade. A1, A2, A3, B4, B5, and C6 are the positioning reference points for measuring the blade body contour after the turbine blade is cast. T is the blade tenon, Y is the blade body, and G is the blade shroud.

[0027] A method for CNC polishing the entire surface of a double-ended shrouded turbine blade, comprising the following steps:

[0028] Step 1: For the double-ended turbine blade after casting, use the upper and lower edge plate design positioning points A1, A2, A3, B4, B5, and C6 to clamp and position the blade, determine the design coordinate system PCS1, and then fix the blade on the 3R quick-change fixture pallet;

[0029] Step 2: The turbine blade fixed on the 3R quick-change fixture tray is then measured using a three-dimensional coordinate measuring machine to obtain blade profile data. The blade positioning geometric elements and the corresponding measurement point data are then aligned in the PCS1 coordinate system (where alignment can be performed using tolerance constraint alignment or unconstrained alignment). The optimal position of the blade reference or coordinate system under the optimal blade profile margin is optimized, which is recorded as PCS2.

[0030] Step 3: According to the spatial conversion relationship between PCS2 and PCS1, perform CNC machining correction on the upper and lower edge plate positioning points A1, A2, A3, B4, B5, and C6 of the blade to obtain the lower edge plate positioning points after fine-tuning;

[0031] Step 4: Finally, the blade body contour error is corrected and the entire surface is CNC polished based on the positioning point of the lower edge plate after the refinement in step 3. Based on this benchmark, the CNC grinding of the blade crown and tenon of the subsequent blade process is also completed at the same time.

[0032] In step 1, the design coordinate system PCS1 is determined by using six points located on the upper and lower edge plates of the blade and calculated based on positioning theory.

[0033] In step 2, a three-coordinate contact measurement method is used to measure the blade. The alignment and positioning process is mainly as follows: the objective function is to minimize the sum of squares of all measurement points and the corresponding theoretical points of the blade body under the premise that the area of ​​the blade body out of tolerance is minimized, and the lower profile tolerance of the blade is used as a constraint condition. A mathematical model for alignment and positioning optimization is established, and a genetic algorithm is used to solve the mathematical model for alignment and positioning to obtain the spatial conversion relationship from PCS1 to PSC2.

[0034] In step three, the blade positioning points are corrected by CNC grinding.

[0035] In step 4, the polishing tool used for CNC polishing of the entire blade surface is a super-hard abrasive complex generatrix flexible polishing wheel.

Claims

1. A method for CNC polishing of the entire surface of a double-ended shrouded turbine blade, characterized by: Here are the steps: Step 1: Design positioning points based on the upper and lower edge plates of the blade after casting, determine the design coordinate system PCS1 based on the six-point positioning theory, and fix the blade on the 3R quick-change fixture pallet. The 3R quick-change fixture pallet is used to accurately position the blade during blade measurement and processing; Step 2: Use a three-dimensional coordinate measuring machine to measure the turbine blade fixed on the 3R quick-change fixture tray to obtain the blade profile data. Then, in the PCS1 coordinate system, align the blade positioning geometric elements and the corresponding measurement point data to optimize the blade reference with the optimal blade profile margin, which is recorded as PCS2. The three-coordinate contact measurement method is used for blade measurement. The registration and positioning process is mainly as follows: the objective function is to minimize the sum of squares of all measurement points and the corresponding theoretical points of the blade body under the premise of minimizing the area of ​​the blade body out of tolerance, and the blade lower profile tolerance is used as the constraint condition. A registration and positioning optimization mathematical model is established, and a genetic algorithm is used to solve the registration and positioning optimization mathematical model to obtain the spatial transformation relationship from PCS1 to PSC2; Step 3: Based on the spatial conversion relationship between PCS2 and PCS1, perform CNC machining correction on the upper and lower edge plate design positioning points of the blade in step 1 to obtain the positioning points after refinement; Step 4: Using the refined positioning point in step 3 as the positioning reference, perform blade body contour polishing correction and full-surface CNC polishing on the turbine blade, and simultaneously complete the CNC grinding of the blade crown and tenon for subsequent processes of the blade based on this positioning reference.

2. The method for CNC polishing of the entire surface of a double-ended shrouded turbine blade according to claim 1, characterized in that: In step three, the positioning points are corrected by CNC grinding.

3. The method for CNC polishing of the entire surface of a double-ended shrouded turbine blade according to claim 1, characterized in that: In step 4, the polishing tool used for CNC polishing of the entire blade surface is a super-hard abrasive complex generatrix flexible polishing wheel.

Images