A method for finishing a top pin for processing a gas turbine turbine blade blank

Abstract

The application discloses a method for finishing a top pin of a turbine blade blank, comprising the following steps: 1. clamping a turbine blade investment casting blank with a top pin boss in a self-centering vice; 2. sending the clamped body to a three-coordinate measuring machine for three-coordinate detection before machining; 3. clamping the clamped body on a numerical control machine tool; 4. according to the positional relationship between the two theoretical set top pin hole cone vertexes on the turbine blade investment casting blank in the self-centering vice coordinate system, finishing the top pin hole machining of the top pin boss; 5. sending the turbine blade investment casting blank to the three-coordinate measuring machine for three-coordinate detection after machining; and 6. comparing the profile data of the same detection section before and after machining, and evaluating whether the top pin machining of the turbine blade investment casting blank is qualified. The application is suitable for the forming particularity of a turbine blade with large structure size, greatly reduces the preparation work before top pin finishing, and has the technical features of small work load, easy operation, low labor intensity, high efficiency and short cycle.

Description

Technical Field

[0001] This invention relates to the forming technology of gas turbine blades, specifically a pin finishing method for processing gas turbine blade blanks. Background Technology

[0002] Gas turbine blades are formed based on precision-cast blanks. Except for the blade root and nearby mounting structures, and some cooling structures in the flow passage that require further machining, the rest of the parts basically retain the structural characteristics of the precision casting itself. The machining of the precision-cast turbine blade blanks is carried out using six positioning references set in the non-machined areas of the blanks. That is, the six positioning references set in the non-machined areas of the blanks serve as positioning references in the machining process. This allows for the detection of the best fit of the profile cross-section and specific machining operations, ultimately resulting in a finished turbine blade with an ideal profile and position.

[0003] The aforementioned forming technology for gas turbine blades is based on smaller-sized turbine blades that are relatively easy to cast. For larger turbine blades, the increased difficulty in casting the precision-cast blanks leads to uncontrollable dimensional deviations. In such cases, using the six-point positioning datum set in the non-machined area of ​​the precision-cast blank as the positioning datum for machining will not yield a finished turbine blade with ideal profile and position. Therefore, for forming larger turbine blades, when machining the precision-cast blank, it is not advisable to directly use the six-point positioning datum set in the non-machined area relied upon by smaller turbine blades. Instead, before machining larger turbine blades, the positioning datum of the precision-cast blank should be converted to a more stable and easier-to-machine datum, and the new positioning datum should be used for subsequent normal machining operations. In other words, for the forming of gas turbine blades with large structural dimensions, it is necessary to first precision machine a new positioning datum on the precision-cast blank. This precision-machined positioning datum is then used as the positioning datum in the mechanical finishing process. Subsequently, the best fit of the profile section and specific mechanical finishing operations are carried out to finally obtain a finished turbine blade with an ideal profile and position.

[0004] Currently, for gas turbine blades with large structural dimensions, the method of adding ejector pin bosses to the precision-cast blanks during molding is based on the conversion of positioning datums. Specifically, the ejector pin holes precision-machined on the ejector pin bosses of the precision-cast blanks are used as the new positioning datums. In this way, the six positioning datums on the precision-cast turbine blade blanks are transferred to the ejector pin holes, and then the ejector pin holes are used as the positioning datums, combined with some of the six positioning datums, for subsequent precision machining operations.

[0005] In existing technologies, the finishing of ejector pins on precision-cast gas turbine blade blanks is achieved using specific positioning fixtures, such as the technology previously disclosed by the applicant entitled "A Method for Positioning and Machining Large-Size Precision-Cast Gas Turbine Blade Blanks," publication number CN 107649845 A, publication date February 2, 2018. Because this type of technology requires specific positioning fixtures for ejector pin finishing, the fixtures must be formed before finishing. The precision requirements for both the forming structure of the positioning fixtures and their assembly on the precision-cast turbine blade blanks are very high. This results in a large workload, cumbersome operation, high labor intensity, and long cycle time in the preparation process before ejector pin finishing, directly reducing the processing efficiency of the turbine blades and increasing processing costs. This is especially evident when the specific positioning fixtures are not universally applicable to different precision-cast turbine blade blanks. Summary of the Invention

[0006] The technical objective of this invention is to provide a method for precision machining of gas turbine blades with large structural dimensions, addressing the unique characteristics of such molding and the shortcomings of existing technologies. This method enables the center pins used for precision machining of precision-cast gas turbine blade blanks to achieve precision molding with ease, convenience, and high efficiency.

[0007] The technical objective of this invention is achieved through the following technical solution: a method for precision machining of ejector pins for gas turbine blade blanks, the method comprising the following process steps:

[0008] Step 1. Clamp the turbine blade precision casting blank with ejector pin boss using a self-centering vise according to the set clamping reference.

[0009] Step 2. The turbine blade precision casting blank clamped in the self-centering vise is sent to the coordinate measuring machine. The ABC coordinate system of the self-centering vise is used for reference positioning, and coordinate measurement is performed before machining.

[0010] To obtain the data of the profile position of each detection section in the profile coordinate system of the precision-cast turbine blade blank under the best fitting state of the profile section, and the data of the position of the pin hole cone surface vertex of the inlet and outlet sides of the precision-cast turbine blade blank in the self-centering vise coordinate system.

[0011] Step 3. Using a quick-change base that matches the self-centering vise, clamp the self-centering vise and the turbine blade precision casting blank it is clamped onto the CNC machine tool, so that the center of the self-centering vise coincides with the spindle center of the CNC machine tool, and the coordinate system of the self-centering vise is consistent with the machining coordinate system of the CNC machine tool.

[0012] Step 4. Based on the two theoretical settings of the inlet and outlet sides of the turbine blade precision casting blank in the self-centering vise coordinate system, set the positional relationship between the vertices of the cone surface of the ejector hole, and input the machining command of the ejector hole to the CNC machine tool;

[0013] Complete the machining of ejector pin holes on the ejector pin bosses of the precision-cast turbine blade blanks;

[0014] Step 5. After the machining in Step 4 is completed, remove the turbine blade precision casting blank clamped in the self-centering vise from the CNC machine tool and remove the turbine blade precision casting blank from the self-centering vise.

[0015] The turbine blade precision casting blank is sent to a coordinate measuring machine. The two ejector pin holes of the turbine blade precision casting blank are used to perform reference positioning in combination with any reference point in the six-point positioning reference set on the turbine blade precision casting blank that is different from the direction of the ejector pin holes. The three-coordinate measurement is then performed after machining.

[0016] To obtain the data of the profile position of each test section of the precision-cast turbine blade blank in the profile coordinate system of the precision-cast blank, as well as the data of the position of other reference points set on the precision-cast turbine blade blank in the profile coordinate system of the precision-cast blank;

[0017] Step 6. Compare the profile position data of each detection section obtained in Step 5 with the profile position data of each detection section obtained in Step 2, and perform profile data comparison for the same detection section.

[0018] If the profile data of the same test section are within the allowable error range when compared before and after processing, the ejector pin of the turbine blade precision casting blank is deemed to be qualified and the turbine blade precision casting blank is transferred to the subsequent normal processing procedure.

[0019] If the profile data of the same test section exceeds the allowable error range when compared before and after processing, the ejector pin processing of the turbine blade precision casting blank is deemed unqualified.

[0020] In step 1, the turbine blade precision casting blank with ejector pin boss has an ejector pin boss protruding at the blade root corresponding to the air intake side and an ejector pin boss protruding at the blade root corresponding to the air outlet side.

[0021] In step 1, the self-centering vise clamps the turbine blade precision casting blank at the blade root.

[0022] During clamping, the air intake side of the precision-cast turbine blade blank corresponds to surface A in the ABC coordinate system of the self-centering vise.

[0023] In step 2, the optimal fit of the profile section of the turbine blade precision casting blank is achieved by using the six-point positioning reference set on the turbine blade precision casting blank for reference positioning.

[0024] The six positioning reference points set on the precision-cast turbine blade blank are distributed as follows:

[0025] At the tenon groove at the leaf root corresponding to the back arc side, there are two reference points spaced out.

[0026] A reference point is arranged at the air intake side of the blade root corresponding to the tenon groove;

[0027] A reference point is arranged on the dorsal arc side of the flow passage near the leaf crown;

[0028] A reference point is arranged on the air intake side of the flow passage near the blade crown;

[0029] A reference point is arranged on the intersecting surface on the back arc side between the leaf root and the flow passage;

[0030] Of the six reference points mentioned above, the first positioning reference is established using three reference points on the back arc side, the second positioning reference is established using two reference points on the intake side, and the radial positioning reference is established using reference points on the intersecting surface.

[0031] Of the six positioning references set on the precision-cast turbine blade blank, in conjunction with the positioning reference of the ejector pin hole, any one of the three reference points on the back arc side is selected for reference positioning. Furthermore, of the six positioning references set on the precision-cast turbine blade blank, in conjunction with the positioning reference of the ejector pin hole, the reference point on the back arc side furthest from the ejector pin hole is selected for reference positioning.

[0032] In step 4, the CNC machine tool is a five-axis CNC machine tool.

[0033] In step 4, the CNC machine tool performs a pecking drill operation on the pin hole.

[0034] In step 6, for turbine blade precision casting blanks that are determined to have unqualified ejector pin machining, the ejector pin holes on the ejector pin boss are ground and repaired by welding.

[0035] After the turbine blade precision casting blank is repaired by welding, repeat steps 1 to 6 until it is deemed to be qualified and then proceed to the subsequent normal processing steps.

[0036] The beneficial technical effects of this invention are as follows: Addressing the unique characteristics of forming large-sized gas turbine blades, the above-mentioned technical measures utilize a self-centering vise as the positioning reference for the inspection, clamping, and precision machining of the turbine blade casting blank. Through specific coordinate data, CNC machine tool clamping, and processing, a positioning reference—the ejector pin hole—is obtained that can serve as the normal precision machining reference for the turbine blade casting blank. In other words, the above-mentioned technical measures eliminate the need for specific positioning fixtures for the precision machining of ejector pins on the turbine blade casting blank; a conventional and versatile self-centering vise can be used easily and efficiently. This significantly reduces the preparation work before ejector pin precision machining, featuring low preparation workload, easy and convenient operation, low labor intensity, high efficiency, and short cycle time. Consequently, it reliably improves the processing efficiency of turbine blades and reduces processing costs, resulting in good economic efficiency. Attached Figure Description

[0037] Figure 1 A schematic diagram of the distribution structure of the six positioning references for the precision machining of turbine blade precision casting blanks.

[0038] Figure 2 This is a schematic diagram of the structure for clamping and positioning a self-centering vise with a precision-cast turbine blade blank.

[0039] Figure 3 This is a schematic diagram of the structure for performing coordinate measuring machine (CMM) inspection on a turbine blade precision casting blank after the ejector pin machining is completed.

[0040] The symbols in the diagram mean: 1—precision casting blank of turbine blade; 11—blade root; 12—flow passage; 13—inlet side; 14—outlet side; 15—tenon; 16—intersecting surface; 17—ejector boss; 18—blade crown; 2—coordinate measuring machine; 3—self-centering vise. Detailed Implementation

[0041] This invention relates to the forming technology of gas turbine blades, specifically a method for precision machining of large-sized gas turbine blade casting blanks (cast blanks with ejector pin bosses). The following description is in conjunction with the accompanying drawings. Figure 1 , Figure 2 and Figure 3 The technical solution of this invention will be clearly and thoroughly explained.

[0042] It should be noted that the accompanying drawings of this invention are schematic, and unnecessary details have been simplified to clarify the technical objectives of this invention, so as to avoid obscuring the technical solutions contributed by this invention to the prior art. Furthermore, the terms "approximately" or "basically" used below to refer to quantities or fit relationships mean that reasonable assembly and processing errors are allowed in the industry, and do not literally describe absolute quantities or fit relationships.

[0043] See Figure 1 As shown, the object to be processed in this invention is a precision-cast turbine blade blank 1 with a ejector pin boss 17. The precision-cast turbine blade blank 1 has a blade root portion 11, a flow passage portion 12, and a blade crown portion 18. According to the usage requirements in the operating environment, the flow passage portion 12 has an inlet side 13, a back arc side, an outlet side 14, and an inner arc side around its perimeter. The blade root portion 11 has a tenon groove 15 for installation, and there is an intersecting surface 16 between the blade root portion 11 and the flow passage portion 12. To achieve precision machining of the gas turbine blade blank 1, which has a relatively large structural size, a raised ejector pin boss 17 is added to the blade root portion 11 corresponding to the inlet side 13, and another raised ejector pin boss 17 is added to the blade root portion 11 corresponding to the outlet side 14. This invention aims to precision machine the ejector pin holes of the two ejector pin bosses 17 on the precision-cast turbine blade blank 1.

[0044] Based on the traditional distribution of positioning references during the precision machining of turbine blade casting blanks, the aforementioned turbine blade casting blank 1 with ejector pin boss 17 theoretically has six positioning references: A1, A2, A3, B1, B2, and C1. The distribution of these six positioning references on the aforementioned turbine blade casting blank 1 with ejector pin boss 17 is as follows:

[0045] The two reference points A1 and A2 are distributed at intervals at the tenon 15 on the back arc side of the leaf root 11.

[0046] The B1 reference point is located at the air intake side 13 of the blade root 11, corresponding to the tenon groove 15.

[0047] A3 is distributed on the dorsal arc side of the flow passage 12 near the leaf crown 18;

[0048] B2 is distributed in the air intake side of the flow passage 12 near the crown 18;

[0049] C1 is distributed on the dorsal arc-shaped intersection surface 16 between the leaf root 11 and the flow passage 12;

[0050] Of the six reference points mentioned above, the first positioning reference is established using three reference points on the back arc side (i.e., A1, A2, and A3), the second positioning reference is established using two reference points on the intake side (i.e., B1 and B2), and the radial positioning reference is established using the reference point on the intersection surface (i.e., C1). When applying these reference points to the coordinate system for positioning, reference points A1, A2, and A3 are used as the positioning surface for the Y-axis, reference points B1 and B2 are used as the positioning surface for the X-axis, and reference point C1 is used as the positioning surface for the Z-axis.

[0051] See Figure 1 Figure 2 and Figure 3As shown, the method for precision machining of the ejector pin of the above-mentioned turbine blade precision casting blank 1 includes the following process steps:

[0052] Step 1. Using a conventional self-centering vise 3, clamp the turbine blade precision casting blank 1 with the ejector pin boss 17 from the blade root 11.

[0053] A detection ABC coordinate system is established based on the self-forming structure of the self-centering vise 3. That is, the direction of the clamping groove is taken as the A surface corresponding to the X-axis, the direction of the clamp translation is taken as the B surface corresponding to the Y-axis, and the side opposite to the clamping groove is taken as the C surface corresponding to the Z-axis.

[0054] When using a self-centering vise 3 to clamp the turbine blade precision casting blank 1, the air intake side 13 of the turbine blade precision casting blank 1 should be aligned with the A surface of the self-centering vise 3; and the relative directions should be consistent in each clamping sequence.

[0055] Step 2. The turbine blade precision casting blank 1 (i.e. the clamping body) clamped by the self-centering vise 3 is sent to the coordinate measuring machine 2. The ABC coordinate system of the self-centering vise 3 is used as the positioning reference. The clamping body is positioned on the coordinate measuring machine 2. The self-centering vise coordinate system is established in the coordinate measuring machine 2 so as to perform coordinate inspection before processing.

[0056] In the coordinate measuring machine 2, the six-point positioning reference theoretically set on the precision casting blank 1 of the turbine blade is used to establish the profile coordinate system of the precision casting blank, and the best fitting state of the profile section of the precision casting blank 1 of the turbine blade is obtained by using the profile coordinate system of the precision casting blank.

[0057] Thus, the three-coordinate measuring machine 2 obtains the data of the profile position of each detection section of the turbine blade precision casting blank 1 in the profile coordinate system of the precision casting blank, as well as the data of the position of the top of the ejector hole cone surface of the inlet and outlet sides of the turbine blade precision casting blank 1 in the self-centering vise coordinate system.

[0058] Output the obtained data;

[0059] Step 3. Using the quick-change base that matches the self-centering vise, clamp the turbine blade precision casting blank 1 (i.e., the clamping body) held in the self-centering vise 3 onto the five-axis CNC machine tool;

[0060] Level and align the position of the self-centering vise 3 on the five-axis CNC machine tool, so that the center of the self-centering vise 3 coincides with the spindle center of the five-axis CNC machine tool, and the coordinate system of the self-centering vise is consistent with the machining coordinate system of the five-axis CNC machine tool; and the relative directions of each clamping sequence should be consistent.

[0061] Step 4. Based on the positional relationship between the two theoretically set ejector hole cone vertices on the inlet and outlet sides of the turbine blade precision casting blank 1 in the self-centering vise coordinate system, confirm the direction of the line connecting the two theoretically set ejector hole cone vertices on the inlet and outlet sides of the turbine blade precision casting blank 1.

[0062] Input the machining command for the ejector pin hole on the precision casting blank 1 of the turbine blade into the five-axis CNC machine tool;

[0063] Select a suitable machining drill bit and machine the corresponding ejector pin boss 17 on the turbine blade precision casting blank 1 using a pecking drilling method; during the machining process, pay attention to the wear of the drill bit, and replace the worn drill bit in time if the drill bit is obviously worn; until both ejector pin holes on the air inlet side and air outlet side of the turbine blade precision casting blank 1 are machined.

[0064] Step 5. After the machining in step 4 is completed, remove the turbine blade precision casting blank 1 clamped by the self-centering vise 3 from the five-axis CNC machine tool, that is, remove the clamping body from the five-axis CNC machine tool;

[0065] Next, remove the turbine blade precision casting blank 1 from the self-centering vise 3, thus separating the clamping body;

[0066] The turbine blade precision casting blank 1 is sent to the coordinate measuring machine 2. Using the two ejector pin holes of the turbine blade precision casting blank 1, combined with the A3 reference point, which is different from the ejector pin hole direction and far away from the ejector pin hole position in the six-point positioning reference set on the turbine blade precision casting blank 1, the turbine blade precision casting blank 1 is reference positioned on the coordinate measuring machine 2. The precision casting blank profile coordinate system is established in the coordinate measuring machine 2 so as to perform three-coordinate inspection after processing through the coordinate measuring machine 2.

[0067] The data of the profile positions of each test section in the profile coordinate system of the precision-cast turbine blade blank 1 after processing are obtained, as well as the data of the positions of other theoretically set reference points (i.e., reference points other than reference point A3 of the six reference points except for the reference point A3 of the ejector pin hole) on the precision-cast turbine blade blank 1 in the profile coordinate system of the precision-cast turbine blade blank 1.

[0068] Output the obtained data;

[0069] Step 6. Compare the profile position data of each detection section obtained in Step 5 (i.e., the data after processing) with the profile position data of each detection section obtained in Step 2 (i.e., the data before processing) to compare the profile data of the same detection section before and after processing.

[0070] If the profile data of the same test section are within the allowable error range when compared before and after processing, the pin finishing of the turbine blade precision casting blank 1 is deemed to be qualified, and the turbine blade precision casting blank 1 is transferred to the subsequent normal mechanical finishing process.

[0071] If the profile data of the same test section exceeds the allowable error range when compared before and after processing, the ejector pin of the turbine blade precision casting blank 1 is determined to be unqualified in precision machining.

[0072] When the precision machining of the ejector pin of the turbine blade precision casting blank 1 is unqualified, the corresponding ejector pin hole of the ejector pin boss 17 on the turbine blade precision casting blank 1 shall be ground and repaired by welding.

[0073] After the turbine blade casting blank is repaired by welding, repeat the finishing process of steps 1 to 6 above until it is judged to be qualified and then proceed to the subsequent normal mechanical finishing process.

[0074] In step 5 above, in conjunction with the reference point of the ejector pin hole, reference point A1 or A2 on the first positioning reference, or the radial positioning reference C1, can be selected. However, reference points B1 and B2 on the second positioning reference cannot be selected, otherwise anti-rotation positioning cannot be achieved. To ensure the stability of the reference positioning, it is best to select reference point A3, which is far away from the ejector pin hole, in the first positioning reference.

[0075] The above specific technical solutions are only used to illustrate the present invention, and are not intended to limit it.

[0076] Although the present invention has been described in detail with reference to the specific technical solutions described above, those skilled in the art should understand that modifications can still be made to the specific technical solutions described above, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the present invention.

Claims

1. A method for precision machining of a center pin for processing gas turbine blade blanks, characterized in that, The ejector pin finishing method includes the following process steps: Step 1. Clamp the turbine blade precision casting blank with ejector pin boss using a self-centering vise according to the set clamping reference. Step 2. The turbine blade precision casting blank clamped in the self-centering vise is sent to the coordinate measuring machine. The ABC coordinate system of the self-centering vise is used for reference positioning, and coordinate measurement is performed before machining. To obtain the data of the profile position of each detection section in the profile coordinate system of the precision-cast turbine blade blank under the best fitting state of the profile section, and the data of the position of the pin hole cone surface vertex of the inlet and outlet sides of the precision-cast turbine blade blank in the self-centering vise coordinate system. Step 3. Using a quick-change base that matches the self-centering vise, clamp the self-centering vise and the turbine blade precision casting blank it is clamped onto the CNC machine tool, so that the center of the self-centering vise coincides with the spindle center of the CNC machine tool, and the coordinate system of the self-centering vise is consistent with the machining coordinate system of the CNC machine tool. Step 4. Based on the two theoretical settings of the inlet and outlet sides of the turbine blade precision casting blank in the self-centering vise coordinate system, set the positional relationship between the vertices of the cone surface of the ejector hole, and input the machining command of the ejector hole to the CNC machine tool; Complete the machining of ejector pin holes on the ejector pin bosses of the precision-cast turbine blade blanks; Step 5. After the machining in step 4 is completed, remove the turbine blade precision casting blank clamped in the self-centering vise from the CNC machine tool and remove the turbine blade precision casting blank from the self-centering vise; The turbine blade precision casting blank is sent to a coordinate measuring machine. The two ejector pin holes of the turbine blade precision casting blank are used to perform reference positioning in combination with any reference point in the six-point positioning reference set on the turbine blade precision casting blank that is different from the direction of the ejector pin holes. The three-coordinate measurement is then performed after machining. To obtain the data of the profile position of each test section of the precision-cast turbine blade blank in the profile coordinate system of the precision-cast blank, as well as the data of the position of other reference points set on the precision-cast turbine blade blank in the profile coordinate system of the precision-cast blank; Step 6. Compare the profile position data of each detection section obtained in Step 5 with the profile position data of each detection section obtained in Step 2, and perform profile data comparison for the same detection section. If the profile data of the same test section are within the allowable error range when compared before and after processing, the ejector pin of the turbine blade precision casting blank is deemed to be qualified and the turbine blade precision casting blank is transferred to the subsequent normal processing procedure. If the profile data of the same test section exceeds the allowable error range when compared before and after processing, the ejector pin processing of the turbine blade precision casting blank is deemed unqualified.

2. The method for precision machining of gas turbine blade blanks using a center pin according to claim 1, characterized in that: In step 1, the turbine blade precision casting blank with ejector pin boss has an ejector pin boss protruding at the blade root corresponding to the air intake side and an ejector pin boss protruding at the blade root corresponding to the air outlet side.

3. The method for precision machining of gas turbine blade blanks using a center pin according to claim 1, characterized in that: In step 1, the self-centering vise clamps the turbine blade precision casting blank at the blade root. During clamping, the air intake side of the turbine blade precision casting blank corresponds to surface A in the ABC coordinate system of the self-centering vise.

4. The method for precision machining of gas turbine blade blanks using a center pin according to claim 1, characterized in that: In step 2, the optimal fit of the profile section of the turbine blade precision casting blank is achieved by using the six-point positioning reference set on the turbine blade precision casting blank for reference positioning.

5. The method for finishing gas turbine blade blanks using a center pin according to claim 1 or 4, characterized in that: The six positioning reference points set on the precision-cast turbine blade blank are distributed as follows: At the tenon groove at the leaf root corresponding to the back arc side, there are two reference points spaced out. A reference point is arranged at the air intake side of the blade root corresponding to the tenon groove; A reference point is arranged on the dorsal arc side of the flow passage near the leaf crown; A reference point is arranged on the air intake side of the flow passage near the blade crown; A reference point is arranged on the intersecting surface on the back arc side between the leaf root and the flow passage; Of the six reference points mentioned above, the first positioning reference is established using three reference points on the back arc side, the second positioning reference is established using two reference points on the intake side, and the radial positioning reference is established using reference points on the intersecting surface.

6. The method for finishing gas turbine blade blanks using a center pin according to claim 5, characterized in that: Among the six positioning references set on the precision-cast billet of the turbine blade, in conjunction with the positioning reference of the ejector pin hole, any one of the three reference points on the back arc side is selected for reference positioning.

7. The method for finishing gas turbine blade blanks using a center pin according to claim 6, characterized in that: Among the six positioning references set on the precision-cast billet of the turbine blade, in the application of the positioning reference for the ejector pin hole, the reference point on the back arc side away from the ejector pin hole is selected for reference positioning.

8. The method for precision machining of gas turbine blade blanks using a center pin according to claim 1, characterized in that: In step 4, the CNC machine tool is a five-axis CNC machine tool.

9. The method for precision machining of gas turbine blade blanks using a center pin according to claim 1, characterized in that: In step 4, the CNC machine tool performs a pecking drill operation on the pin hole.

10. The method for precision machining of gas turbine blade blanks using a center pin according to claim 1, characterized in that: In step 6, for turbine blade precision casting blanks that are determined to have unqualified ejector pin machining, the ejector pin holes on the ejector pin boss are ground and repaired by welding. After the turbine blade precision casting blank is repaired by welding, repeat steps 1 to 6 until it is deemed to be qualified and then proceed to the subsequent normal processing steps.

Images