Steam turbine blade frequency measurement clamp

Abstract

The utility model provides a steam turbine blade frequency measurement clamp, which comprises a working table, a clamp, a jacking mechanism, a sensor and a controller, the clamp is fixed on the working table, the middle part of the clamp is provided with a wheel groove matched with a blade root, the blade root is inserted in the wheel groove, the wheel groove is a through groove, and the jacking mechanism is arranged on the clamp. A limiting part in clearance fit with the blade root is arranged in the wheel groove; the weight of the clamp is 50 times larger than that of the blade; the jacking mechanism is arranged below the workbench and used for jacking the bottom of the blade root, and the jacking mechanism is matched with the limiting part to abut the blade root against the wheel groove; the sensor is arranged at the upper end of the blade and used for collecting frequency data, and the controller is electrically connected with the sensor and used for processing the frequency data transmitted by the sensor. The blade positioning device is simple in structure, simple and convenient to operate, capable of quickly positioning the blade, stable and uniform in positioning stress, and capable of improving the measurement precision and the measurement efficiency.

Description

Technical Field

[0001] The utility model relates to the technical field of steam turbine blade manufacturing, in particular to a steam turbine blade frequency measuring fixture. Background Art

[0002] As a core power equipment, the operating status of the steam turbine is crucial. The moving blades will be affected by various forces during operation, which may cause the blades to vibrate. In order to ensure the safe operation of the steam turbine, it is necessary to test the static natural frequency of the steam turbine moving blades to ensure the stability and consistency of the blade natural frequency. However, the traditional frequency measurement method has problems such as inconvenient operation, poor stability, and low accuracy, which leads to unstable final measurement results, long time consumption, and low efficiency. Utility Model Content

[0003] The utility model aims to provide a turbine blade frequency measuring fixture to overcome the shortcomings in the prior art.

[0004] In order to solve the above technical problems, the technical solution of the utility model is: a turbine blade frequency measuring fixture, including a workbench, a fixture, a lifting mechanism, a sensor, and a controller. The fixture is fixed on the workbench, and a wheel groove matched with the blade root is provided in the middle of the fixture. The blade root is inserted in the wheel groove, and the wheel groove is a through groove, and a limiting part matched with the blade root gap is provided inside the wheel groove; the weight of the fixture is greater than 50 times the weight of the blade; the lifting mechanism is arranged under the workbench, and is used to lift the bottom of the blade root, and the lifting mechanism cooperates with the limiting part to press the blade root against the wheel groove; the sensor is arranged at the upper end of the blade, and is used to collect frequency data. The controller is electrically connected to the sensor, and is used to process the frequency data transmitted by the sensor.

[0005] Furthermore, in the above-mentioned turbine blade frequency measuring fixture, the wheel groove is a trapezoidal groove that is larger at the top and smaller at the bottom, and the limiting portion is arranged on two side edges of the trapezoidal groove, including a plurality of arc-shaped teeth arranged along the side edges.

[0006] Furthermore, in the above-mentioned turbine blade frequency measuring fixture, the wheel groove width is greater than the width of the blade root.

[0007] Furthermore, in the above-mentioned turbine blade frequency measuring fixture, the upper lifting mechanism includes a jack, a plunger, and a lifting block. The jack is fixed under the workbench, and a plunger is provided at its output end. A lifting block is provided above the plunger to abut against the plunger, and the lifting block is movably connected to the bottom of the blade root.

[0008] Furthermore, in the above-mentioned turbine blade frequency measuring fixture, a guide groove connected to the wheel groove is provided at the bottom of the fixture, the guide groove is adapted to the shape of the top block, and is a stepped cylindrical through groove, the top block is arranged in the guide groove and is slidably connected to the guide groove.

[0009] Furthermore, in the above-mentioned turbine blade frequency measuring fixture, the top block is a split structure, divided into a lower top block and an upper top block by an arc surface.

[0010] Furthermore, the above-mentioned turbine blade frequency measuring fixture, the fixture is an inverted T-block, the wheel groove is arranged on the boss at the upper end of the fixture and passes through the front and rear sides of the boss, and the fixture is fixedly connected to the workbench by bolts arranged on both sides of the boss at the upper end of the fixture.

[0011] Furthermore, in the above-mentioned steam turbine blade frequency measuring fixture, hanging rings are provided on the step surfaces on both sides of the boss at the upper end of the fixture.

[0012] Compared with the prior art, the utility model has the following beneficial effects: simple structure, easy operation, ability to quickly realize blade positioning, stable and uniform positioning force, and improved measurement accuracy and efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0014] Figure 1 This is a schematic diagram of the structure of the turbine blade frequency measuring fixture of the utility model;

[0015] Figure 2 It is a cross-sectional view of the frequency measuring fixture of the steam turbine blade of the utility model;

[0016] Figure 3 This is a schematic diagram of the fixture structure of the turbine blade frequency measuring fixture of the utility model;

[0017] Figure 4 This is a schematic diagram of the top block structure of the turbine blade frequency measuring fixture of the utility model;

[0018] In the figure: 1. workbench; 2. fixture; 21. wheel groove; 22. limit part; 23. guide groove; 3. sensor; 4. jack; 5. plunger; 6. top block; 61. lower top block; 62. upper top block; 7. bolt; 8. lifting ring; 9. blade. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0020] Example 1

[0021] like Figure 1-4 As shown, a turbine blade frequency measuring fixture comprises a workbench 1, a fixture 2, a top mechanism, a sensor 3, and a controller. The fixture 2 is fixed on the workbench 1. A wheel groove 21 matching the blade root of the blade 9 is provided in the middle of the fixture 2. The blade root of the blade 9 is inserted in the wheel groove 21. The width of the wheel groove 21 is greater than the width of the blade root of the blade 9, so that the contact part between the blade root and the wheel groove 21 is in a fully wrapped state, the contact area is maximized, and the stability of the frequency measuring fixture is further improved; the wheel groove 21 is a through groove, and the wheel groove 21 is provided with a gap matching the blade root gap. The weight of the clamp 2 is greater than 50 times the weight of the blade 9. The mass of the clamp 2 should be much greater than the mass of the blade 9 to avoid the influence of the vibration frequency of the clamp 2 itself on the vibration frequency of the blade and ensure the accuracy of the frequency measurement result; the upper push mechanism is arranged under the workbench 1, and is used to push the bottom of the blade root. The upper push mechanism cooperates with the limiting part 22 to press the blade root against the wheel groove 21; the sensor 3 is arranged at the upper end of the blade 9, and is used to collect frequency data. The controller is electrically connected to the sensor and is used to process the frequency data transmitted by the sensor.

[0022] The end of sensor 3 that contacts the blade has a signal collector, which is adsorbed on blade 9. The mass of the signal collector on sensor 3 should be small, and the impact on the blade frequency measurement result can be ignored. A micro acceleration sensor 1A803E can be used. When blade 9 vibrates, the collected signal is transmitted to the controller, which can be a computer, a remote control terminal, etc., and the blade frequency measurement data is obtained through specific analysis software.

[0023] like Figure 1-3 As shown, the wheel groove 21 is a trapezoidal groove that is larger at the top and smaller at the bottom. The limiting portion 22 is arranged on the two sides of the trapezoidal groove, including a plurality of arc-shaped teeth arranged along the sides. The blade root is provided with an arc-shaped convex tooth that cooperates with the arc-shaped teeth. Through the tooth shape cooperation, the blade root and the clamp are more tightly matched when the blade root receives the upward force, and the force distribution of the contact surface is uniform when the force is applied, thereby improving the clamping stability.

[0024] Example 2

[0025] Based on the structure of Example 1, Figure 1 , 2As shown, the lifting mechanism includes a jack 4, a plunger 5, and a lift block 6. The jack 4 is fixed below the workbench 1, and a plunger 5 is provided at its output end. A lift block 6 is provided above the plunger 5 to abut against the plunger 5, and the lift block 6 is movably connected to the bottom of the blade root. The plunger 5 plays a role in transmitting force, and the pressure can be freely adjusted to a desired pressure value by adjusting the pressure adjustment button on the jack 4.

[0026] In the above structure, if Figure 4 As shown, the top block 6 is a split structure, which is divided into a lower top block 61 and an upper top block 62 by a circular arc surface. When subjected to an upward extrusion force, the top block 6 may tilt, and the force is uneven, which may easily damage the root of the blade 9. The split top block divided by the circular arc surface can solve this problem, and can adapt to the force in all directions to ensure that the tightening force on the blade root is uniform and stable.

[0027] Among them, Figure 2 As shown, the bottom of the clamp 2 is provided with a guide groove 23 connected to the wheel groove 21, the guide groove 23 is adapted to the shape of the top block 6, and is a stepped cylindrical through groove, the top block 6 is arranged in the guide groove 23, and is slidably connected with the guide groove 23. The guide groove 23 guides the extrusion direction of the top block 6, further ensuring that the tightening force on the blade root is uniform and stable.

[0028] In addition, if Figure 1 , 3 As shown, the fixture 2 is an inverted T-block, the wheel groove 21 is provided on the boss at the upper end of the fixture 2 and penetrates the front and rear sides of the boss, and the fixture 2 is fixedly connected to the workbench 1 by bolts 7 provided on both sides of the boss at the upper end of the fixture 2. The fixture 2 needs to be tightened with the specified bolts 7, the torque meets the frequency measurement requirements, and the tightening degree of each bolt 7 is ensured to be as consistent as possible to prevent the fixture 2 from shaking during the vibration process due to partial overtightening or over-loosening of the bolts, which further leads to inaccurate measurement results.

[0029] like Figure 1 As shown, in order to facilitate the handling of the clamp 2, the step surfaces on both sides of the upper end boss of the clamp 2 are also provided with lifting rings 8. Since the clamp 4 is heavy, it is inconvenient to clamp and disassemble the clamp 4. The lifting ring 8 is provided at a position that does not affect the clamping of the blade 9, which can be better handled.

[0030] The installation method and working principle of the frequency measuring fixture of the utility model are as follows:

[0031] During installation, first check the working condition of the jack 4 to see if it can operate normally, and then put the plunger 5 prepared in advance on the jack. Then, fix the fixture 2 to the workbench 1 with bolts 7, tighten it with professional tools, and ensure that the tightening degree of each bolt is as consistent as possible; when installing the fixture 2, put the separate top block 6 together and put it into the guide hole 23 under the fixture 2. Then insert the root of the blade 9 from one side of the wheel groove 21, and install it in coordination with the wheel groove on the fixture 2, trying to keep it in the middle position so that the contact part between the blade root and the wheel groove 21 is in a fully wrapped state. It should be noted that before the blade 9 is installed in the fixture, it is also necessary to carefully check whether there are burrs on the blade root and the wheel groove 21. If there are burrs, they should be removed in advance.

[0032] After the frequency measuring fixture is adjusted and installed, the sensor 3 is adsorbed on the upper end of the blade 9. In order to easily obtain accurate frequency measurement data, the installation position of the sensor is as close to the small end of the blade 9 as possible and in the middle of the inner back arc; there is a signal collector at one end of the sensor 3, which should be firm and reliable when adsorbed on the blade 9, and will not shake or fall off with the vibration of the blade, and cannot cause damage to the blade; the other end of the sensor 3 is connected to the controller, which has professional frequency data analysis software. Then start the jack 4, give an appropriate pressure value, press the root of the blade 9 against the wheel groove 21, and then use a special knocking device to knock the blade 9 near the small end. The data collection of the sensor 3 cannot be affected. The direction of the knocking should be consistent with the vibration direction of the blade 9. After multiple knocks, the vibration frequency of the blade (the natural frequency of the blade itself) is obtained through the analysis software, the average value of the blade is determined, and the data is recorded. In addition, when measuring the same type of blades produced in batches, standard sample blades can be established; for different batches, the frequency measuring fixture can be verified by disassembling and reassembling the standard test piece blades multiple times before measurement. If the change value is within the allowable tolerance, the qualification of the test fixture can be determined.

[0033] In summary, the frequency measuring fixture of the utility model has a simple structure, is easy to operate, can quickly realize the positioning of the blade, and the positioning force is stable and uniform, thereby improving the measurement accuracy and measurement efficiency.

[0034] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be regarded as exemplary and non-restrictive from any point of view, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention. Any reference numeral in a claim should not be regarded as limiting the claim to which it relates.

[0035] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A frequency measuring fixture for steam turbine blades, characterized in that: It includes a workbench, a clamp, a lifting mechanism, a sensor, and a controller. The clamp is fixed on the workbench. A wheel groove matched with the blade root is provided in the middle of the clamp. The blade root is inserted in the wheel groove. The wheel groove is a through groove, and a limiting part matched with the blade root gap is provided inside the wheel groove. The weight of the clamp is greater than 50 times the weight of the blade. The lifting mechanism is arranged under the workbench and is used to lift the bottom of the blade root. The lifting mechanism cooperates with the limiting part to press the blade root against the wheel groove. The sensor is arranged at the upper end of the blade and is used to collect frequency data. The controller is electrically connected to the sensor and is used to process the frequency data transmitted by the sensor.

2. The turbine blade frequency measuring fixture according to claim 1, characterized in that: The wheel groove is a trapezoidal groove that is larger at the top and smaller at the bottom. The limiting portion is arranged on two side edges of the trapezoidal groove and includes a plurality of arc-shaped teeth arranged along the side edges.

3. The turbine blade frequency measuring fixture according to claim 1, characterized in that: The wheel groove width is greater than the width of the blade root.

4. The turbine blade frequency measuring fixture according to any one of claims 1 to 3, characterized in that: The lifting mechanism comprises a jack, a plunger and a lifting block. The jack is fixed under the workbench, and a plunger is arranged at its output end. A lifting block abutting against the plunger is arranged above the plunger, and the lifting block is movably connected to the bottom of the blade root.

5. The turbine blade frequency measuring fixture according to claim 4, characterized in that: The bottom of the clamp is provided with a guide groove communicated with the wheel groove, the guide groove is matched with the shape of the top block, the top block is arranged in the guide groove and is slidably connected with the guide groove.

6. The turbine blade frequency measuring fixture according to claim 4, characterized in that: The top block is a split structure, which is divided into a lower top block and an upper top block by an arc surface.

7. The turbine blade frequency measuring fixture according to claim 1, characterized in that: The clamp is an inverted T-block, the wheel groove is arranged on the boss at the upper end of the clamp and passes through the front and rear sides of the boss, and the clamp is fixedly connected to the workbench by bolts arranged on both sides of the boss at the upper end of the clamp.

8. The frequency measuring fixture for steam turbine blades according to claim 7, characterized in that: The step surfaces on both sides of the boss at the upper end of the clamp are also provided with hanging rings.

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