Gas turbine blade centre hole depth measuring method

Abstract

The invention relates to the field of precision casting, and particularly discloses a gas turbine blade centre hole depth measuring method, which comprises the following steps: analyzing a centre hole section structure and a magnetic bead contact state size through UG drawing software, performing sectioning analysis on a gas turbine blade centre hole axis surface, performing tangent constraint on a magnetic bead contour and a centre hole inner contour, and determining the depth of the centre hole; measuring the distance from the center of the magnetic bead to the inner end of the centre hole; putting the magnetic bead into the centre hole of the blade, measuring the center position of the magnetic bead by adopting a three-coordinate measuring instrument, and calculating the actual centre hole depth of the blade by combining the dimension guarantee of the three-coordinate measuring instrument on the profile tolerance of the inner wall of the centre hole; according to the method, by means of the tangent constraint of the magnetic bead and the centre hole in the blade tenon, the hub degree of the magnetic bead is measured through the three-coordinate measuring instrument, the depth of the centre hole is calculated, the depth of the centre hole can be accurate to 0.01 mm, the measurement precision is high, and the precision of follow-up positioning and clamping machining of the gas turbine blade through the centre hole is guaranteed.

Description

Technical Field

[0001] The present invention relates to the field of precision casting, and specifically to a method for measuring the depth of the thimble hole of a gas turbine blade. Background Art

[0002] The thimble hole of a gas turbine blade (as shown in Figure 1 ) is a small hole specially machined on the gas turbine blade for positioning, clamping and supporting. During the manufacturing process of the gas turbine blade, the thimble hole plays a crucial role. It provides a reference for the accurate installation and fixation of the blade on the processing equipment. For example, in machining processes such as milling and grinding, through the cooperation of the thimble and the thimble hole, it can ensure that the blade is stable and precise during processing, thus guaranteeing the dimensional accuracy, shape accuracy and surface quality of the blade, etc. In the assembly link, the thimble hole is also an important basis for the accurate assembly of the blade with other components, enabling the blade to be in the correct position and angle on components such as the rotor or stator of the gas turbine, and ensuring the overall aerodynamic and mechanical performance of the gas turbine. Therefore, the accuracy requirements for the thimble hole of a gas turbine blade are very strict, including dimensional accuracy, position accuracy and shape accuracy, etc. The dimensional accuracy can usually be controlled at the micron level. The position accuracy requires the thimble holes to be accurately distributed on the blade. The shape accuracy needs to ensure that the cylindricity, straightness, etc. of the holes meet the design standards to ensure the reliability and stability of the blade during assembly and use.

[0003] The thimble hole of a gas turbine blade is not only precisely sized but also narrow. Usually, high-precision measuring tools such as coordinate measuring machines and pneumatic gauges are used to accurately measure the size of the thimble hole of the gas turbine blade to ensure that it meets the design dimensional tolerance range. The most commonly used is to use a coordinate measuring machine for measurement. The detection method of the coordinate measuring machine is to accurately measure the position, size, etc. of the thimble hole by the coordinate measuring machine. By contacting the surface of the thimble hole with the measuring probe, the actual coordinate values of the hole are obtained and compared with the design values to determine whether the thimble hole meets the requirements. However, the tip of the measuring probe is a spherical structure. Coupled with the narrow size of the thimble hole, it cannot reach the innermost end of the thimble hole (as shown in Figure 2 , Figure 3 ), and there is a deviation in the measured depth value of the thimble hole, and the accurate depth of the thimble hole cannot be accurately measured. For this reason, the present application proposes a method for measuring the depth of the thimble hole of a gas turbine blade to solve the above problems. Summary of the Invention

[0004] In view of the existing problems, the present invention provides a method for measuring the depth of the thimble hole of a gas turbine blade, which can effectively solve the problems raised in the background art.

[0005] To solve the above problems, the present invention adopts the following technical solutions:

[0006] A method for measuring the depth of a pinhole of a gas turbine blade comprises the following steps:

[0007] S1. Measurement preparation: Select the magnetic bead, analyze the cross-sectional structure of the ejector hole and the contact state of the magnetic bead using UG drawing software, and analyze the cross-sectional surface of the ejector hole of the turbine blade. Constrain the contour of the magnetic bead to be tangent to the inner contour of the ejector hole, and measure the distance from the center of the magnetic bead to the inner end of the ejector hole.

[0008] S2. Actual measurement: Place the magnetic bead into the ejector hole of the blade, use a three-coordinate measuring machine to measure the contour of the magnetic bead, determine the center position of the magnetic bead, combine the dimensional assurance of the inner wall contour of the ejector hole by the three-coordinate measuring machine, and the distance from the center of the magnetic bead to the inner end of the ejector hole measured by UG drawing software, calculate the actual ejector hole depth of the blade.

[0009] As a further solution of the present invention: in step S1, there are two magnetic beads, which are respectively used for the ejector holes on both sides of the blade tenon.

[0010] As a further solution of the present invention: the diameter of the magnetic beads in step S1 is 6 mm, and the sphericity tolerance and size tolerance are ±0.002 mm.

[0011] As a further solution of the present invention: in the step S2, a magnetic support is placed at the center of the tenon end surface of the blade, and the magnetic support is consistent with the outline size of the tenon of the blade.

[0012] As a further solution of the present invention: the magnetic beads and the magnetic supports are both made of magnetic materials with strong magnetism.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention uses the tangent constraint of the magnetic bead and the ejector hole on the blade tenon to measure the hub degree of the magnetic bead by a three-coordinate measuring instrument to calculate the depth of the ejector hole, and the depth of the ejector hole can be accurate to 0.01mm with high measurement accuracy, avoiding the error caused by the inability of the three-coordinate measuring instrument's measuring probe to penetrate the innermost end of the ejector hole in the conventional measurement method, thereby ensuring the accuracy of the subsequent positioning and clamping processing of the gas turbine blade through the ejector hole. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic diagram of the structure of existing gas turbine blades;

[0015] Figure 2 This is a cross-sectional schematic diagram of the three-dimensional coordinate measuring machine probe measuring the ejector hole;

[0016] Figure 3 for Figure 2 The enlarged schematic diagram at A in the middle;

[0017] Figure 4It is a schematic diagram of measuring the ejector hole in the present invention;

[0018] Figure 5 Schematic diagram of the measurement cross section of the ejector hole in the present invention;

[0019] Figure 6 for Figure 5 Enlarged schematic diagram of point B in the middle.

[0020] In the figure: 1. Blade; 2. Tenon; 3. Ejector hole; 4. Measuring probe; 5. Gap between measuring probe and inner end of ejector hole; 6. Magnetic bead; 7. Magnetic support. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] Combination Figures 4 to 6 This embodiment describes a method for measuring the depth of a pinhole in a gas turbine blade, which comprises the following steps:

[0023] S1. Measurement preparation: Select the magnetic bead, analyze the cross-sectional structure of the ejector hole and the contact state of the magnetic bead through UG drawing software, and analyze the cross-sectional surface of the ejector hole of the turbine blade. Constrain the contour of the magnetic bead to be tangent to the inner contour of the ejector hole, and measure the distance from the center of the magnetic bead to the inner end of the ejector hole. In this case, the distance is 6.81 mm.

[0024] S2. Actual measurement: Place the magnetic bead into the ejector hole of the blade, use the measuring probe of the three-dimensional coordinate measuring machine to measure the contour of the magnetic bead, determine the center position of the magnetic bead, combine the dimensional guarantee of the inner wall contour of the ejector hole by the three-dimensional coordinate measuring machine, and the distance from the center of the magnetic bead to the inner end of the ejector hole measured by UG drawing software, calculate the actual ejector hole depth of the blade.

[0025] In specific implementation, two magnetic beads are selected. During measurement, the two magnetic beads are respectively used for the thimble holes on both sides of the blade tenon. The diameter of the magnetic bead is 6 mm, and the sphericity tolerance and dimensional tolerance are ±0.002 mm. The external dimensions of the magnetic bead need to be precisely controlled. The sphericity tolerance of the used magnetic bead is ±0.002 mm. On the premise of ensuring the tolerance, the coordinate measuring machine can lock the center coordinates through spherical measurement. The thimble hole is machined from the casting by the precision machining machine according to the theoretical size of the thimble hole. According to the cross-sectional geometry of the thimble hole, the inner wall contour is related to the apex position of the thimble hole tip and is consistent. According to the center position of the magnetic bead, the tangency constraint position between the opening contour of the thimble hole and the outer contour of the magnetic bead can be calculated. Since the apex position of the thimble hole tip is in a narrow position and the probe of the coordinate measuring machine cannot penetrate directly to measure the coordinate of this point, the depth of the thimble hole cannot be measured. By attaching the spherical magnetic bead to the inner wall and then measuring the center of the magnetic bead with the coordinate measuring machine, the distance from the center of the bead to the apex of the thimble hole tip can be obtained through geometric operations, and at the same time, the depth of the thimble hole can be calculated.

[0026] During actual measurement, since most of the gas turbine blades are nickel-based superalloys, the alloy material itself has no magnetism or very weak magnetism, and the magnetic beads cannot be firmly attracted at the thimble holes. At this time, place the blade tenon upward and place a magnetic support in the center above the tenon. The magnetic support matches the contour size of the blade tenon. The wall thickness of the magnetic support is 10 - 20 mm. Both the magnetic beads and the magnetic support are made of magnetic materials with strong magnetism. Keep the magnetic support stable, and then place the magnetic beads at the thimble holes on both sides of the blade tenon. Due to the strong magnetic attraction of the magnetic beads and the magnetic support, the two magnetic beads will closely adhere to the inner wall of the thimble hole and will not fall off (as Figure 4 shown), keep the placement state of the blade, and use a coordinate measuring machine to measure the contour of the magnetic ball.

[0027] It should be noted that the ruby probe at the tip of the measuring probe of the coordinate measuring machine cannot ensure that it is tangent to the circumferential surface of the conical surface of the thimble hole every time during measurement, so it cannot directly replace the magnetic bead in the present invention.

[0028] The working principle of the present invention is: through the tangency constraint between the magnetic bead and the thimble hole on the blade tenon, by measuring the hub degree of the magnetic bead with a coordinate measuring machine, the depth of the thimble hole is deduced. The depth of the thimble hole can be accurate to 0.01 mm, with high measurement accuracy, avoiding the error caused by the inability of the measuring probe of the coordinate measuring machine to penetrate into the innermost end of the thimble hole in the conventional measurement method, and ensuring the accuracy of subsequent positioning and clamping processing of the gas turbine blade through the thimble hole.

[0029] It should be noted that in this text, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or elements inherent to such process, method, article or device.

[0030] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for measuring the depth of a pinhole in a gas turbine blade, characterized in that: The steps include: S1. Measurement preparation: Select the magnetic bead, analyze the cross-sectional structure of the ejector hole and the contact state of the magnetic bead using UG drawing software, and analyze the cross-sectional surface of the ejector hole of the turbine blade. Constrain the contour of the magnetic bead to be tangent to the inner contour of the ejector hole, and measure the distance from the center of the magnetic bead to the inner end of the ejector hole. S2. Actual measurement: Place the magnetic bead into the ejector hole of the blade, use a three-coordinate measuring machine to measure the contour of the magnetic bead, determine the center position of the magnetic bead, combine the dimensional assurance of the inner wall contour of the ejector hole by the three-coordinate measuring machine, and the distance from the center of the magnetic bead to the inner end of the ejector hole measured by UG drawing software, calculate the actual ejector hole depth of the blade.

2. A method for measuring the pinhole depth of a gas turbine blade according to claim 1, characterized in that: In step S1, there are two magnetic beads, which are respectively used for the ejector holes on both sides of the blade tenon.

3. The method for measuring the pinhole depth of a gas turbine blade according to claim 1, characterized in that: In step S1, the diameter of the magnetic beads is 6 mm, and the sphericity tolerance and size tolerance are ±0.002 mm.

4. The method for measuring the pinhole depth of a gas turbine blade according to claim 1, characterized in that: In step S2, a magnetic support is placed at the center of the tenon end surface of the blade, and the magnetic support is consistent with the outline size of the tenon of the blade.

5. A method for measuring the pinhole depth of a gas turbine blade according to claim 4, characterized in that: The magnetic beads and the magnetic support are both made of magnetic materials with strong magnetism.

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