CN-118417912-B - Thimble finish machining method for machining turbine blade blank of gas turbine

CN118417912BCN 118417912 BCN118417912 BCN 118417912BCN-118417912-B

Abstract

The invention discloses a thimble finish machining method for machining a turbine blade blank of a gas turbine, which comprises the steps of 1, clamping a turbine blade finish casting blank with a thimble boss by a self-centering vice, 2, feeding a clamping body to a three-coordinate measuring machine for three-coordinate detection before machining, 3, clamping the clamping body on a numerical control machine, 4, finishing the thimble machining of the thimble boss according to the position relation between two theoretical setting thimble hole conical surface vertexes on the turbine blade finish casting blank in the self-centering vice coordinate system, 5, feeding the turbine blade finish casting blank to the three-coordinate measuring machine for three-coordinate detection after machining, 6, comparing line data of the same detection section before and after machining, and judging whether the thimble machining of the turbine blade finish casting blank is qualified or not. Aiming at the special forming of the turbine blade with larger structural size, the invention greatly reduces the preparation work before the finish machining of the thimble, and has the technical characteristics of small workload, easy operation, low labor intensity, high efficiency and short period.

Inventors

YAN YI
Gou Jingjing
XIE JIAKE
XIONG XIAOCONG
DONG QIANG
XU JIALIANG
TAN JIANGANG
ZHOU YUNBO
LIAO LONG
CHEN JIANHUI
BAO XINGJIN

Assignees

东方电气集团东方汽轮机有限公司

Dates

Publication Date: 20260512
Application Date: 20240520

Claims (10)

1. The thimble finish machining method for machining the turbine blade blank of the gas turbine is characterized by comprising the following steps of: step 1, precisely casting a blank of the turbine blade with a thimble boss, and clamping the blank by a self-centering vice according to a set clamping reference; step 2, the turbine blade precision casting blank clamped by the self-centering vice is sent to a three-coordinate measuring machine, reference positioning is carried out by using an ABC coordinate system of the self-centering vice, and three-coordinate detection before machining is carried out; The method comprises the steps of obtaining data of line positions of all detection sections in a line coordinate system of a precision casting blank piece under a line section best fitting state of a turbine blade precision casting blank before machining, and data of vertex positions of top pinhole conical surfaces theoretically set on an air inlet side and an air outlet side of the turbine blade precision casting blank in a self-centering vice coordinate system; Step 3, clamping the self-centering vice and the clamped turbine blade precision casting blank on the numerical control machine through a quick-change base matched with the self-centering vice, so that the center of the self-centering vice is coincident with the center of a main shaft of the numerical control machine, and the coordinate system of the self-centering vice is coincident with the processing coordinate system of the numerical control machine; step 4, setting the position relationship between the conical surface peaks of the top pin holes according to two theories of the air inlet side and the air outlet side of the turbine blade precision casting blank piece in a self-centering vice coordinate system, and inputting a processing instruction of the top pin holes into a numerical control machine; finishing a thimble hole on a thimble boss on the turbine blade precision casting blank; Step 5, after the machining in the step 4 is finished, taking down the turbine blade precision casting blank clamped by the self-centering vice from the numerical control machine tool, and taking down the turbine blade precision casting blank from the self-centering vice; sending the turbine blade precision casting blank to a three-coordinate measuring machine, carrying out reference positioning by combining two top pinholes of the turbine blade precision casting blank and any reference point which is different from the direction of the top pinholes in six-point positioning references set on the turbine blade precision casting blank, and carrying out three-coordinate detection after processing; The method comprises the steps of obtaining data of the molded line positions of all detection sections in a molded line coordinate system of the fine casting blank of the turbine blade after machining and data of other reference point positions set on the fine casting blank of the turbine blade in the molded line coordinate system of the fine casting blank; Step 6, comparing the molded line position data of each detection section obtained in the step 5 with the molded line position data of each detection section obtained in the step 2 to perform molded line data comparison of the same detection section; if the comparison result of the molded line data of the same detection section before and after the processing is within the allowable error range, judging that the thimble of the turbine blade casting blank is qualified for processing, and converting the turbine blade casting blank into the subsequent normal processing procedure; And if the comparison result of the molded line data of the same detection section before and after the processing exceeds the allowable error range, judging that the thimble of the turbine blade precision casting blank is unqualified in processing.
2. The method of refining a thimble for a turbine blade blank of a combustion engine according to claim 1, wherein: In step 1, a turbine blade precision casting blank with thimble bosses is formed by protruding a thimble boss at a position corresponding to an air inlet side of a blade root part, and a thimble boss is formed by protruding a position corresponding to an air outlet side of the blade root part.
3. The method of refining a thimble for a turbine blade blank of a combustion engine according to claim 1, wherein: in the step 1, clamping a turbine blade precision casting blank piece at the blade root part of the turbine blade precision casting blank piece by a self-centering vice; During clamping, the air inlet side of the turbine blade precision casting blank corresponds to the A surface in the ABC coordinate system of the self-centering vice.
4. The method of refining a thimble for a turbine blade blank of a combustion engine according to claim 1, wherein: in the step 2, the best fitting state of the molded line section of the turbine blade precision casting blank is based on six-point positioning references set on the turbine blade precision casting blank.
5. The method of refining pins for machining a turbine blade blank of a gas turbine in accordance with claim 1 or 4, wherein: Six-point positioning reference distribution set on the turbine blade precision casting blank is as follows: Two datum points are distributed at intervals at the positions of the blade root part corresponding to the mortises on the back arc side; a datum point is arranged at the air inlet side of the blade root part corresponding to the mortise; a datum point is arranged at the back arc side of the through-flow part, which is close to the tip shroud part; a datum point is arranged at the position, close to the air inlet side of the blade shroud, of the through-flow part; a datum point is arranged on a back arc side intersecting surface between the blade root and the through flow part; Of the six reference points, a first positioning reference is established by three reference points on the back arc side, a second positioning reference is established by two reference points on the air inlet side, and a radial positioning reference is established by the reference points on the intersecting surface.
6. A method for refining a thimble for machining a turbine blade blank of a combustion engine according to claim 5, wherein: And in the six-point positioning reference set on the turbine blade precision casting blank, any one of the three reference points on the back arc side is selected for reference positioning in the application of matching with the positioning reference of the top pinhole.
7. The method of refining a thimble for machining a turbine blade blank of a gas turbine of claim 6, wherein: And in the six-point positioning reference set on the turbine blade precision casting blank, in the application of matching with the positioning reference of the top pinhole, selecting a reference point of which the back arc side is far away from the top pinhole to perform reference positioning.
8. The method of refining a thimble for a turbine blade blank of a combustion engine according to claim 1, wherein: in the step 4, the numerical control machine tool is a five-axis numerical control machine tool.
9. The method of refining a thimble for a turbine blade blank of a combustion engine according to claim 1, wherein: in the step 4, the processing of the top pinhole by the numerical control machine tool is pecking processing.
10. The method of refining a thimble for a turbine blade blank of a combustion engine according to claim 1, wherein: In the step 6, judging the turbine blade precision casting blank with unqualified thimble processing, polishing and repair welding the thimble holes on the thimble boss; And (3) repeating the processing treatment of the steps 1 to 6 until the turbine blade fine casting blank subjected to repair welding is judged to be qualified, and then, converting the turbine blade fine casting blank into the subsequent normal processing procedure.

Description

Thimble finish machining method for machining turbine blade blank of gas turbine Technical Field The invention relates to a forming technology of a turbine blade of a gas turbine, in particular to a thimble finish machining method for machining a turbine blade blank of the gas turbine. Background The turbine blade of the gas turbine is formed based on the precision casting blank, and the rest basically maintains the structural characteristics of the precision casting except that the blade root and the mounting structure nearby and the partial cooling structure of the through flow part need to be further mechanically finished. The mechanical finish machining of the turbine blade finish casting blank is carried out by using the six-point positioning reference set by the non-machining area of the turbine blade finish casting blank, namely, the six-point positioning reference set by the non-machining area of the turbine blade finish casting blank is used as the positioning reference in the mechanical finish machining, so that the operations of detecting the best fit of the molded line section, specific mechanical finish machining and the like are carried out, and finally, the finished turbine blade with the profile contour and the position in ideal states is obtained. The forming technology of the turbine blade of the gas turbine is based on the premise of relatively easy casting and forming of the turbine blade with smaller structural size. For the turbine movable blade with larger structural size, the casting technical difficulty of the fine casting blank piece of the turbine blade is increased, and dimensional deviation which is difficult to control exists, and if the six-point positioning reference set in the non-processing area of the fine casting blank piece of the turbine blade is used as the positioning reference in mechanical fine processing, the finished turbine blade with ideal profile contour and ideal position cannot be obtained. Therefore, for forming the turbine movable blade with larger structural size, when the mechanical finish machining is performed on the cast blank, six-point positioning references are not set in a non-machining area on which the turbine blade with smaller structural size depends in the finish machining, but the positioning references of the cast blank are converted into more stable and more convenient-to-machine references before the mechanical finish machining is performed on the turbine blade with larger structural size, and the subsequent normal mechanical finish machining operation is performed by using the converted new positioning references. That is, for the forming of the turbine blade of the gas turbine with larger structural size, a new positioning reference needs to be finished on the cast blank, the finished positioning reference is used as the positioning reference in the mechanical finishing, and then the operations of the best fitting detection of the molded line section, the specific mechanical finishing and the like are carried out, so that the finished turbine blade with the profile contour and the position in the ideal state is finally obtained. Currently, when a turbine blade of a combustion engine with a larger structural size is formed, a structure of adding a thimble boss on a precision casting blank is used as a basis for conversion of a positioning reference, namely, a thimble hole machined on the thimble boss of the precision casting blank is used as a new positioning reference obtained by conversion. In this way, the six-point positioning reference on the turbine blade precision casting blank is converted to the top pinhole, and then the top pinhole is used as the positioning reference to combine with part of the six-point positioning reference to carry out the subsequent mechanical precision machining operation. In the prior art, the fine machining of the thimble on the fine cast blank of the turbine blade of the gas turbine is realized by a specific positioning tool, for example, the inventor discloses a technique of positioning and machining the fine cast blank of the turbine blade of the gas turbine with a large size, with publication number CN 107649845A, publication date 2018, 02 and 02. The positioning tool with a specific structure is needed in the thimble finish machining, so that the positioning tool with the specific structure is firstly used for forming before the thimble finish machining, and the accuracy requirements on the forming structure of the positioning tool and the assembling structure on the turbine blade precision casting blank are very high, so that the technical problems of large workload, troublesome operation, high labor intensity and long period exist in the preparation process before the thimble finish machining, the machining efficiency of the turbine blade is directly reduced, and the machining cost is increased. This is particularly evident in the case of positioning tools of a specific construction, without versa