Off-line measurement method for throat size of steam turbine blade

Abstract

The invention discloses an off-line measurement method for the throat size of a turbine blade, and relates to the technical field of turbines. The objective of the invention is to solve the problems that when the size of a blade throat is directly measured on a rotor in the prior art, the blade falls down under the influence of the gravity of the blade, so that the size of the throat is changed, the measurement result has a large error, and the real size of the blade throat cannot be accurately reflected. The method comprises the following steps that 1, a blade is horizontally installed on a comprehensive measuring tool, the steam outlet side of the blade is arranged downwards, the steam inlet side of the blade is parallel to a bottom plate of the comprehensive measuring tool, and the blade is fixed in a tenon tooth clamping mode; 2, a special sample plate is placed at the throat diameter position meeting the design requirement; through combined calculation of special sample plate light leakage data and the theoretical throat size of the adjacent blade, measurement errors are eliminated, angle conversion is utilized, differences in different measurement scenes are fully considered, the throat size measurement precision is remarkably improved, and the real size of the blade throat is accurately reflected.

Description

Technical Field

[0001] This invention relates to the field of steam turbine technology, and more specifically to an offline measurement method for the throat dimensions of steam turbine blades. Background Technology

[0002] In the manufacturing process of steam turbine blades, the throat size is a critical parameter, and its measurement accuracy directly affects the working efficiency and performance of the steam turbine.

[0003] Currently, the traditional method requires measuring the throat size of turbine blades on a pre-assembled disk. This method requires pre-assembling the blades onto the disk and then measuring the throat size after the clearance is measured, which depends on the assembly progress.

[0004] This method has certain limitations. When measuring directly on the rotor without using a pre-installed wheel, the blade will fall downwards due to its own weight, which will cause changes in the throat size and result in a large error in the measurement results. It cannot accurately reflect the true size of the blade throat and cannot trace the blade manufacturing deviations separately.

[0005] In summary, existing methods for directly measuring the blade throat size on the rotor result in the blade falling downwards due to its own weight, causing changes in the throat size and leading to significant measurement errors that fail to accurately reflect the true size of the blade throat. Summary of the Invention

[0006] The purpose of this invention is to address the problem that existing methods for directly measuring the throat size of turbine blades on the rotor suffer from significant errors due to the blades' own weight causing them to sag downwards and altering the throat size, thus failing to accurately reflect the true dimensions of the blade throat. Therefore, this invention provides an offline method for measuring the throat size of turbine blades.

[0007] The technical solution of this invention is: an offline measurement method for the throat dimension of a steam turbine blade, comprising the following steps:

[0008] Step 1: Install the blade horizontally on the integrated measuring tool, with the steam outlet side of the blade facing down and the steam inlet side parallel to the base plate of the integrated measuring tool. The blade is fixed by clamping tenons.

[0009] Step 2: Place a special template at the throat diameter position required by the design;

[0010] Step 3: Set the theoretical throat dimension between adjacent finished blade airfoil surfaces as follows: The actual light leakage gap between the special template and the inner arc of the blade passage was measured. The actual light leakage gap between the special template and the back arc of the blade steam passage. ;

[0011] Step 4: Based on the parameters in Step 3, calculate the actual throat dimensions between adjacent finished blade airfoil surfaces. ;

[0012] Step 5: Determine the actual throat dimensions between the airfoil surfaces of adjacent finished blades under the conditions of installing the blades in the comprehensive measuring tool. Converted to the actual throat dimensions between adjacent finished blade airfoil surfaces when the blades are installed on a pre-assembled wheel disc. .

[0013] Furthermore, in step one, the comprehensive measuring tool needs to pre-compile the inspection of the steam passage, tie rod, surrounding belt working surface, and intermediate body parts.

[0014] Furthermore, in step two, the outline of the special template matches the cross-sectional outline of the blade throat, and the coefficient of thermal expansion of the template material is consistent with that of the blade material.

[0015] Furthermore, in step three, the theoretical throat dimension between adjacent finished blade airfoil surfaces... It is a fixed value, and The measurement values ​​at the corresponding positions of the inner arc and back arc of the steam passage are the same for different blades.

[0016] Furthermore, in step four, the actual throat dimensions between adjacent finished blade airfoil surfaces... The calculation steps are as follows:

[0017] The theoretical throat dimension between adjacent finished blade airfoil surfaces The actual light leakage gap between the special template and the inner arc of the blade passage. The actual light leakage gap between the special template and the back arc of the blade steam passage. Substituting into equation (1), the actual throat dimensions between adjacent finished blade airfoil surfaces are calculated. ;

[0018] = +( - ) + ( - (1)。

[0019] Furthermore, the calculation steps for the actual throat dimensions between adjacent finished blade airfoil surfaces under the pre-assembled wheel disk condition in step five are as follows:

[0020] The actual throat dimension between the airfoil surfaces of adjacent finished blades under the condition of installing the blades in a comprehensive measuring tool. Substituting into equation (2), the actual throat dimensions between adjacent finished blade airfoil surfaces under the condition of blades installed on a pre-assembled wheel disk are calculated. ;

[0021] = (2);

[0022] In equation (2), The angle of the blade's radiation.

[0023] Furthermore, in equation (2), The calculation steps are as follows;

[0024] = ,in Let n be the number of blades installed, and n is a positive integer greater than 1.

[0025] Furthermore, the measurement process in steps one through five must be carried out in a constant temperature environment, with the ambient temperature controlled at 20℃±2℃.

[0026] Furthermore, in step three, the measurement and At this time, at least three measurement points should be evenly selected along the circumference of the throat diameter, and the average value of the measurements at each point should be taken as the final value. and .

[0027] Furthermore, the measurement method is applicable to turbine blades of different specifications, requiring only adjustment based on the blade's throat design diameter and the number of turbines installed. By determining the values ​​of n, the corresponding blade throat size can be measured.

[0028] Compared with the prior art, the present invention has the following advantages:

[0029] 1. The offline measurement method for the throat size of steam turbine blades provided by the present invention eliminates measurement errors by combining the light leakage data of a special template with the theoretical throat size of adjacent blades. Then, by utilizing angle conversion, it fully considers the differences under different measurement scenarios, significantly improves the measurement accuracy of throat size, and accurately reflects the true size of the blade throat.

[0030] 2. The offline measurement method for the throat size of turbine blades provided by this invention abandons the traditional pre-installed wheel disk measurement method and completes the measurement directly on the comprehensive measuring tool, reducing operation steps and greatly improving measurement efficiency.

[0031] 3. The offline measurement method for the throat size of steam turbine blades provided by this invention can be applied to steam turbine blades of different specifications. The throat size can be accurately obtained simply by adjusting the variables in the calculation formula according to the number of blades and design parameters. It has strong versatility. Attached Figure Description

[0032] Figure 1 This is a schematic diagram showing the state of the blade of the present invention installed on the comprehensive measuring tool;

[0033] Figure 2 This is a schematic diagram showing the state of the blades and the special template of this invention;

[0034] Figure 3 This is a schematic diagram of the state between adjacent blades of the present invention. Detailed Implementation

[0035] Specific implementation method one: Combining Figures 1 to 3 This embodiment describes the following steps:

[0036] Step 1: Install the blade horizontally on the integrated measuring tool, with the steam outlet side of the blade facing down and the steam inlet side parallel to the base plate of the integrated measuring tool. The blade is fixed by clamping tenons.

[0037] Step 2: Place a special template at the throat diameter position required by the design;

[0038] Step 3: Set the theoretical throat dimension between adjacent finished blade airfoil surfaces as follows: The actual light leakage gap between the special template and the inner arc of the blade passage was measured. The actual light leakage gap between the special template and the back arc of the blade steam passage. ;

[0039] Step 4: Based on the parameters in Step 3, calculate the actual throat dimensions between adjacent finished blade airfoil surfaces. ;

[0040] Step 5: Determine the actual throat dimensions between the airfoil surfaces of adjacent finished blades under the conditions of installing the blades in the comprehensive measuring tool. Converted to the actual throat dimensions between adjacent finished blade airfoil surfaces when the blades are installed on a pre-assembled wheel disc. .

[0041] It should be noted that during the blade processing, the blade must be mounted on a comprehensive measuring tool. The purpose of this tool is to inspect the working surfaces of the steam passage, tie rods, profiles, and intermediate parts. This embodiment also measures the throat dimensions on the comprehensive measuring tool, saving the installation step. This not only results in more accurate results but also increases blade processing efficiency. The tenon teeth on the blade are used for positioning, and the blade tip engages with the center pin on the comprehensive measuring tool for fixation. When measuring the light leakage gap, feeler gauges or other tools can be used. The theoretical throat dimensions between the curved surfaces of adjacent finished blades are also measured. Its value is fixed, and the measurement values ​​are the same at the corresponding measurement positions of the inner arc and back arc of the steam passage in different blades.

[0042] The offline measurement method for the throat size of turbine blades provided in this embodiment eliminates measurement errors by combining the light leakage data of a dedicated template with the theoretical throat size of adjacent blades. Furthermore, by utilizing angle conversion, it fully considers the differences under different measurement scenarios, significantly improving the measurement accuracy of the throat size and accurately reflecting the true size of the blade throat.

[0043] Specific Implementation Method Two: Combining Figures 1 to 3 This embodiment differs from the specific embodiment in that, in step one, the comprehensive measuring tool needs to pre-test the steam passage, tie rod, surrounding belt working surface, and intermediate body parts to ensure that the measuring tool's accuracy meets the measurement requirements. Other components and connections are the same as in specific embodiment one.

[0044] Specific implementation method three: Combining Figures 1 to 3 This embodiment differs from Specific Embodiment One in that, in step two, the outline of the special template matches the cross-sectional outline of the blade throat, and the coefficient of thermal expansion of the template material is consistent with that of the blade material, thereby avoiding the influence of temperature on measurement accuracy. Other components and connections are the same as in Specific Embodiment One.

[0045] Specific implementation method four: Combination Figures 1 to 3 This embodiment differs from specific embodiment three in that, in step three, the theoretical throat dimension between adjacent finished blade airfoil surfaces... It is a fixed value, and The measurement values ​​at the corresponding positions of the inner arc and back arc of the steam passage are the same for different blades. Other components and connections are the same as in Specific Implementation Method 1.

[0046] Specific Implementation Method Five: Combining Figures 1 to 3 This embodiment differs from specific embodiment one in that the actual throat size between adjacent finished blade airfoil surfaces in step four is described. The calculation steps are as follows:

[0047] The theoretical throat dimension between adjacent finished blade airfoil surfaces The actual light leakage gap between the special template and the inner arc of the blade passage. The actual light leakage gap between the special template and the back arc of the blade steam passage. Substituting into equation (1), the actual throat dimensions between adjacent finished blade airfoil surfaces are calculated. ;

[0048] = +( - ) + ( - (1)。

[0049] Other components and connections are the same as in Specific Implementation Method 1.

[0050] Specific Implementation Method Six: Combination Figures 1 to 3 This embodiment differs from Specific Embodiment One in that the calculation steps for the actual throat dimensions between adjacent finished blade airfoil surfaces under the pre-assembled wheel disk condition in step five are as follows:

[0051] The actual throat dimension between the airfoil surfaces of adjacent finished blades under the condition of installing the blades in a comprehensive measuring tool. Substituting into equation (2), the actual throat dimensions between adjacent finished blade airfoil surfaces under the condition of blades installed on a pre-assembled wheel disk are calculated. ;

[0052] = (2);

[0053] In equation (2), Let be the blade radiation angle. Assume the throat dimension measured when the blade is in position 0 (flat on the integrated measuring tool with no angle, and the inlet side parallel to the base plate of the tool) is... The throat dimension when the blade is mounted on the pre-installed wheel at an angle θ is: Based on trigonometric function relationships, a relationship conversion is required between the two, that is... = By converting the throat dimensions measured on the comprehensive measuring tool, the throat dimensions are transformed to conform to the actual throat dimensions of the blade in its pre-installed state on the pre-mounted wheel, ensuring that the measurement results are consistent with the actual working conditions. Other components and connections are the same as in Specific Implementation Method 1.

[0054] Specific implementation method seven: Combination Figures 1 to 3This embodiment differs from specific embodiment six in that, in equation (2), The calculation steps are as follows;

[0055] = ,in The number of blades installed is n, where n is a positive integer greater than 1. Other components and connections are the same as in Specific Implementation Method Six.

[0056] Specific implementation method eight: Combination Figures 1 to 3 This embodiment differs from Specific Embodiment 1 in that the measurement processes in steps one through five must be performed in a constant temperature environment, with the ambient temperature controlled at 20℃±2℃. Other components and connections are the same as in Specific Embodiment 1.

[0057] Specific Implementation Method Nine: Combining Figures 1 to 3 This embodiment differs from specific embodiment one in that, in step three, the measurement... and At this time, at least three measurement points should be evenly selected along the circumference of the throat diameter, and the average value of the measurements at each point should be taken as the final value. and The other components and connections are the same as in Specific Implementation Method 1.

[0058] Specific Implementation Method Ten: Combining Figures 1 to 3 This embodiment differs from specific embodiment seven in that the measurement method described herein is applicable to turbine blades of different specifications, requiring only adjustment based on the blade's throat design diameter and the number of turbine blades installed. The value of n allows for the measurement of the corresponding blade throat size. Other components and connections are the same as in Specific Implementation Method Seven.

[0059] The content of this invention is not limited to the above-described embodiments; a combination of one or more specific embodiments can also achieve the purpose of the invention.

Claims

1. An offline measurement method for the throat dimensions of a steam turbine blade, characterized in that, Includes the following steps: Step 1: Install the blade horizontally on the integrated measuring tool, with the steam outlet side of the blade facing down and the steam inlet side parallel to the base plate of the integrated measuring tool. The blade is fixed by clamping tenons. Step 2: Place a special template at the throat diameter position required by the design; Step 3: Set the theoretical throat dimension between adjacent finished blade airfoil surfaces as follows: The actual light leakage gap between the special template and the inner arc of the blade passage was measured. The actual light leakage gap between the special template and the back arc of the blade steam passage. ; Step 4: Based on the parameters in Step 3, calculate the actual throat dimensions between adjacent finished blade airfoil surfaces. ; Step 5: Determine the actual throat dimensions between the airfoil surfaces of adjacent finished blades under the conditions of installing the blades in the comprehensive measuring tool. Converted to the actual throat dimensions between adjacent finished blade airfoil surfaces when the blades are installed on a pre-assembled wheel disc. .

2. The offline measurement method for the throat dimension of a steam turbine blade according to claim 1, characterized in that, In step one, the comprehensive measuring tool needs to complete the inspection of the steam passage, tie rod, surrounding belt working surface and intermediate body parts in advance.

3. The offline measurement method for the throat dimension of a steam turbine blade according to claim 1, characterized in that, In step two, the outline of the special template matches the cross-sectional outline of the blade throat, and the thermal expansion coefficient of the template material is consistent with that of the blade material.

4. The offline measurement method for the throat dimension of a steam turbine blade according to claim 1, characterized in that, In step three, the theoretical throat dimension between adjacent finished blade airfoil surfaces It is a fixed value, and The measurement values ​​at the corresponding positions of the inner arc and back arc of the steam passage are the same for different blades.

5. The offline measurement method for the throat dimension of a steam turbine blade according to claim 1, characterized in that, In step four, the actual throat size between adjacent finished blade airfoil surfaces The calculation steps are as follows: The theoretical throat dimension between adjacent finished blade airfoil surfaces The actual light leakage gap between the special template and the inner arc of the blade passage. The actual light leakage gap between the special template and the back arc of the blade steam passage. Substituting into equation (1), the actual throat dimensions between adjacent finished blade airfoil surfaces are calculated. ; = +（ - ）+（ - ） （1）。 6. The offline measurement method for the throat dimension of a steam turbine blade according to claim 1, characterized in that, The calculation steps for the actual throat dimensions between adjacent finished blade airfoil surfaces under the pre-assembled wheel disk condition in step five are as follows: The actual throat dimension between the airfoil surfaces of adjacent finished blades under the condition of installing the blades in a comprehensive measuring tool. Substituting into equation (2), the actual throat dimensions between adjacent finished blade airfoil surfaces under the condition of blades installed on a pre-assembled wheel disk are calculated. ; = （2）； In equation (2), The angle of the blade's radiation.

7. The offline measurement method for the throat dimension of a steam turbine blade according to claim 6, characterized in that, In the above formula (2), The calculation steps are as follows; = ,in Let n be the number of blades installed, and n is a positive integer greater than 1.

8. The offline measurement method for the throat dimension of a steam turbine blade according to claim 1, characterized in that, The measurement process in steps one through five must be carried out in a constant temperature environment, with the ambient temperature controlled at 20℃±2℃.

9. The offline measurement method for the throat dimension of a steam turbine blade according to claim 1, characterized in that, In step three, measurement and At this time, at least three measurement points should be evenly selected along the circumference of the throat diameter, and the average value of the measurements at each point should be taken as the final value. and .

10. The offline measurement method for the throat dimension of a steam turbine blade according to claim 7, characterized in that, The measurement method is applicable to turbine blades of different specifications, and only needs to be adjusted according to the design diameter of the blade throat and the number of turbines installed. By determining the values ​​of n, the corresponding blade throat size can be measured.

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