A steam turbine rotor blade self-mounted crown damping plate structure and disassembly and assembly method

Abstract

The present invention discloses a structure and disassembly method of a damping plate with a crown of a steam turbine moving blade. The radial surfaces of both sides of the crown of the steam turbine moving blade are provided with flat damping holes and the saddle damping plates are placed in the holes. The steam turbine moving blade includes a plurality of standard blades provided with ordinary damping holes and at least one locking blade provided with a sealed damping hole. The locking blade has a threaded hole extending from one side of the radial surface of the crown into the sealed damping hole on the edge of the radial surface of the crown and the sealed damping hole. A fastening screw is installed in the threaded hole, and the front end of the fastening screw extends into the sealed damping hole and the two sides of the screw nut are punched and riveted. The length of the sealed damping hole is greater than the sum of the length of the ordinary damping hole and the inner diameter of the threaded hole. The present invention adopts a detachable structure, and the saddle damping plate is sealed by reinforcing it through a screw structure and punching and riveting. The present invention has the advantages of simple structure, easy disassembly and assembly, and the ability to remove the locking blade without damage, which can effectively ensure the overall maintenance period of the unit.

Description

Technical Field

[0001] The invention relates to a steam turbine moving blade, in particular to a steam turbine moving blade self-attached crown damping sheet structure and a disassembly and assembly method. Background Art

[0002] The blade is the heart of the steam turbine and the main element of energy conversion. For a long time, the economy and safety of steam turbine blades have been of concern to people. For quite a long time, the turbine blades have been using the riveted structure of the belt group (or the double ring group). Later, in some Western countries, the moving blades with their own crowns (or self-belts) pre-twisted ring structure appeared. Compared with the former, the latter not only improves the economy and safety, but also greatly reduces the labor and strength of blade assembly. However, in order to implement its pre-twisting, the radial surface processing and assembly requirements of the blade crown are high, which increases the cost. In recent years, the moving blade self-crown damping pin structure has appeared. Although this structure reduces the processing and assembly costs to a certain extent compared with the pre-twisted ring structure, the thickness of the blade crown is significantly thickened because the damping pin hole needs to be processed on the blade crown, which not only increases the centrifugal force, but also is not conducive to the stator flow design; at the same time, this structure has at least two sealing blades per stage, and the processing and welding amount are large, and the welding heat affected zone is large.

[0003] In order to solve the above problems, a Chinese patent document discloses a "steam turbine impeller self-crown damping plate structure" (publication number CN2469184, publication date January 2, 2002). This technology discloses a steam turbine impeller self-crown damping plate structure, wherein the radial surfaces on both sides of the impeller crown have flat damping holes for placing the saddle damping plates, the edges of the holes have deep chamfers, and the damping plates are chamfered all around; the tops of the two sealing blades have sealing pins, and the sealing pins have sealing welds; the depth of the damping hole of the sealing blade increases by the diameter of a sealing pin compared to the damping hole of the standard blade. This structure uses a smaller damping plate and reduces the size of the impeller crown, which not only greatly facilitates the flow design of the steam turbine, but also reduces the centrifugal force of the blades and increases the frequency modulation margin of the blade design. It has the characteristics of thin impeller crown, less processing and welding of the sealing blades, and easy assembly.

[0004] However, in actual use, for turbine blades using this damping structure, the locking blade (sealing blade) shroud uses sealing pins and molten metal to seal the damping plate. When removing the locking blade, the locking blade needs to be destroyed in order to remove the damping plate. Since some blades in the stage may be repaired or replaced during maintenance, the current structure will damage the locking blade when removing some blades in the stage, and the cycle required to supplement the production of new locking blades is relatively long, which seriously affects the overall maintenance period of the unit. Summary of the invention

[0005] The purpose of the present invention is to provide a turbine moving blade self-contained crown damping plate structure which is simple in structure, easy to install and disassemble and can remove the locking blade without damage, in view of the shortcomings of the prior art.

[0006] The technical purpose of the present invention is achieved by the following technical solutions:

[0007] A steam turbine moving blade with a crown damping plate structure, wherein radial surfaces on both sides of the blade crown of the steam turbine moving blade are provided with flat damping holes and saddle damping plates are placed in the holes; the steam turbine moving blade comprises a plurality of standard blades provided with ordinary damping holes and at least one locking blade provided with a sealed damping hole, wherein the locking blade has a threaded hole extending from one side of the blade crown radial surface into the sealed damping hole on the edge of the blade crown radial surface and the sealed damping hole; a fastening screw is installed in the threaded hole, and the front end of the fastening screw extends into the sealed damping hole and rivets the two sides of the nut; the length of the sealed damping hole is greater than the sum of the length of the ordinary damping hole and the inner diameter of the threaded hole.

[0008] The inner diameter of the threaded hole is less than or equal to the height of the sealed damping hole.

[0009] The length of the threaded hole is slightly greater than the width of the sealing damping hole, and the length of the front end of the screw extending into the sealing damping hole is less than the width of the sealing damping hole.

[0010] According to the present invention, a method for installing a turbine rotor blade with a crown damping plate structure comprises the following steps:

[0011] S1. During the assembly of turbine blades, standard blades are assembled first and locking blades are assembled last;

[0012] S2. Before inserting the locking blade, place the saddle damping sheet between the locking blade and the adjacent standard blade in the sealing damping hole;

[0013] S3. Install the locking blade, and use a special tool to move the saddle damping plate between the locking blade and the standard blade to the side close to the standard blade; then screw in the fastening screws and rivet both sides of the screw nut.

[0014] A method for removing a turbine rotor blade self-supporting crown damping plate structure according to the present invention comprises the following steps:

[0015] M1. Lightly polish and remove the rivet points of the screw nut, and then remove the fastening screw;

[0016] M2. Turn the rotor to make the riding damping sheet between the locking blade and the standard blade move into the sealing damping hole;

[0017] M3. Remove the locking blade without damage.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. The locking blade of the present invention adds a threaded hole extending from one side of the radial surface of the blade crown into the sealing damping hole on the edge of the sealing damping hole; a fastening screw is installed in the threaded hole, and the front end of the fastening screw extends into the sealing damping hole and rivets the two sides of the nut; the length of the sealing damping hole is greater than the sum of the length of the ordinary damping hole and the inner diameter of the threaded hole. Compared with the existing technology of sealing the saddle damping plate by sealing pins and molten welding metal, the present invention adopts a detachable structure, and seals the saddle damping plate by reinforcing the screw structure and rivets; when the unit is overhauled, the locking blade can be protectively removed, and then the standard blades (in-stage blades) can be taken out in turn for grinding or replacement. After completion, it can be reassembled without the need to produce new locking blades. The adoption of this technical measure has the advantages of simple structure, easy disassembly and assembly, and the ability to remove the locking blades without damage, which can effectively ensure the overall maintenance period of the unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the structure of the present invention without fastening screws installed;

[0021] Figure 2 for Figure 1 EE section view;

[0022] Figure 3 This is a schematic diagram of the structure of the present invention after the fastening screws are assembled;

[0023] Figure 4 for Figure 3 EE section view;

[0024] Figure 5 for Figure 3 A-direction structural schematic diagram;

[0025] Figure numerals: 1—middle locking blade; 11—first sealed damping hole; 2—standard blade on the back arc side; 21—ordinary damping hole; 3—locking blade on the inner arc side; 31—second sealed damping hole; 4—threaded hole; 5—saddle damping plate; 6—fastening screw. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0027] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. 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.

[0028] It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings. In addition, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0029] like Figure 1 — Figure 5 As shown, a steam turbine moving blade with a crown damping plate structure, flat damping holes are provided on the radial surfaces of the blade crown on both sides of the steam turbine moving blade, and a saddle damping plate 5 is placed in the hole; the steam turbine moving blade includes a plurality of standard blades with ordinary damping holes 21 and at least one locking blade with a sealed damping hole, and the locking blade is provided with a threaded hole 4 extending from one side of the blade crown radial surface into the sealed damping hole on the edge of the blade crown radial surface and the sealed damping hole; a fastening screw 6 is installed in the threaded hole 4, and the front end of the fastening screw 6 extends into the sealed damping hole and riveted on both sides of the screw nut; the length of the sealed damping hole is greater than the sum of the length of the ordinary damping hole 21 and the inner diameter of the threaded hole 4. Compared with the existing technology of sealing the saddle damping plate 5 with sealing pins and molten metal, the present invention adopts a detachable structure, and seals the saddle damping plate 5 by reinforcing it with screw structures and punching and riveting; when the unit is overhauled, the locking blades can be protectively removed, and then the standard blades (blades within the stage) can be taken out in turn for grinding or replacement. After completion, it can be reassembled without the need to produce new locking blades. The adoption of this technical measure has the advantages of simple structure, easy disassembly and assembly, and the ability to remove the locking blades without damage, which can effectively ensure the overall maintenance period of the unit.

[0030] Specifically, the turbine rotor blades include two locking blades and a plurality of standard blades, wherein the locking blades include an intermediate locking blade 1 and an inner arc side locking blade 3 arranged on one side of the intermediate locking blade 1, and a back arc side standard blade 2 is arranged on the side away from the inner arc side locking blade 3. The intermediate locking blade 1 is combined with the back arc side standard blade 2 and the inner arc side locking blade 3 to form two sealed damping holes. The intermediate locking blade 1 and the back arc side standard blade 2 form a first sealed damping hole 11; the intermediate locking blade 1 and the inner arc side locking blade 3 form a second sealed damping hole 31. Both the first sealed damping hole 11 and the second sealed damping hole 31 are provided with a threaded hole 4 extending from one side of the blade crown radial surface into the sealed damping hole, wherein the threaded hole 4 is arranged on the blade crown radial surface and the edge of the sealed damping hole. When the saddle damping plate 5 is installed, the fastening screw 6 is screwed into the threaded hole 4, and the two sides of the screw nut are riveted to prevent the screw from rotating.

[0031] In actual use, the inner diameter of the threaded hole 4 is equal to the height of the sealed damping hole, and the inner diameter of the threaded hole 4 is less than or equal to the height of the sealed damping hole, that is, the inner diameter of the threaded hole 4 is less than or equal to the height of the first sealed damping hole 11 and the second sealed damping hole 31.

[0032] The gap-matching between the riding damping sheet 5 and the common damping hole 21 and the sealed damping hole is a clearance fit, and the overall length, width and height of the riding damping sheet 5 are smaller than those of the common damping hole 21 and the sealed damping hole.

[0033] The length of the threaded hole 4 is slightly greater than the width of the sealing damping hole, and the length of the front end of the screw extending into the sealing damping hole is less than the width of the sealing damping hole; that is, the front end of the screw will not abut against the inner wall of the sealing damping hole. This technical measure can, to a certain extent, avoid the front end of the screw from contacting the inner wall of the sealing damping hole, which may cause damage during the subsequent punching and riveting.

[0034] In actual use, a method for installing a turbine rotor blade self-mounted crown damping sheet structure according to the present invention comprises the following steps:

[0035] S1. During the assembly of turbine blades, standard blades are assembled first and locking blades are assembled last;

[0036] S2. Before inserting the locking blade, the intermediate locking blade 1 and its adjacent back arc side standard blade 2 between the gap damping sheet 5 is placed in the first sealing damping hole 11; the intermediate locking blade 1 and the inner arc side locking blade 3 between the gap damping sheet 5 is placed in the second sealing damping hole 31;

[0037] S3. Install the middle locking blade 1, use special tools to push the saddle damping plate 5 between the middle locking blade 1 and the standard blade 2 on the back arc side to the side of the standard blade 2 on the back arc side, screw in the fastening screw 6, and rivet both sides of the screw nut to prevent the screw from rotating; push the saddle damping plate 5 between the middle locking blade 1 and the inner arc side locking blade 3 to the side of the middle locking blade 1, screw in the fastening screw 6, and rivet both sides of the screw nut to prevent the screw from rotating.

[0038] Compared with the existing technology, the new structure and method can quickly complete the assembly between the standard blades and the locking blades of the turbine blades, which can effectively improve the work efficiency.

[0039] In actual use, a method for disassembling a turbine rotor blade self-attached crown damping sheet structure provided by the present invention comprises the following steps:

[0040] M1. First, lightly polish and remove the rivet points of the screw nut, and then unscrew the fastening screw 6;

[0041] M2. Rotate the rotor to move the gap-riding damping plate 5 between the middle locking blade 1 and the back arc side standard blade 2 into the first sealing damping hole 11; and move the gap-riding damping plate 5 between the middle locking blade 1 and the inner arc side locking blade into the second sealing damping hole 31.

[0042] M3. Remove the middle locking blade 1 and the inner arc side locking blade without damage.

[0043] Compared with the existing technology, the new structure and method can ensure that the locking blades can be quickly removed during later maintenance. At the same time, it can ensure that the locking blades will not be damaged, thereby reducing the time required to supplement the production of new locking blades and ensuring the overall maintenance period of the unit.

[0044] The technical solutions provided by the embodiments of the present invention are introduced in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the embodiments of the present invention. The description of the above embodiments is only applicable to help understand the principles of the embodiments of the present invention. At the same time, for those skilled in the art, according to the embodiments of the present invention, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A steam turbine rotor blade with a crown damping plate structure, wherein the radial surfaces of the blade crown on both sides of the steam turbine rotor blade are provided with flat damping holes and the slotted damping plates are placed in the holes; the steam turbine rotor blade comprises a plurality of standard blades with ordinary damping holes and at least one locking blade with a sealed damping hole, characterized in that: The locking blade has a threaded hole extending from one side of the radial surface of the blade crown into the sealed damping hole at the edge of the sealed damping hole; a fastening screw is installed in the threaded hole, and the front end of the fastening screw extends into the sealed damping hole and riveted on both sides of the screw nut; the length of the sealed damping hole is greater than the sum of the length of the ordinary damping hole and the inner diameter of the threaded hole.

2. The steam turbine rotor blade self-crown damping plate structure according to claim 1, characterized in that: The inner diameter of the threaded hole is less than or equal to the height of the sealed damping hole.

3. The steam turbine rotor blade self-crown damping plate structure according to claim 1, characterized in that: The length of the threaded hole is slightly greater than the width of the sealing damping hole, and the length of the front end of the screw extending into the sealing damping hole is less than the width of the sealing damping hole.

4. A method for installing a turbine rotor blade with a crown damping plate structure, characterized in that: The method for installing the turbine rotor blade self-crown damping sheet structure according to any one of claims 1 to 3 comprises the following steps: S1. During the assembly of turbine blades, standard blades are assembled first and locking blades are assembled last; S2. Before inserting the locking blade, place the saddle damping sheet between the locking blade and the adjacent standard blade in the sealing damping hole; S3. Install the locking blade, and use a special tool to move the saddle damping plate between the locking blade and the standard blade to the side close to the standard blade; then screw in the fastening screws and rivet both sides of the screw nut.

5. A method for removing a self-crown damping plate structure of a steam turbine rotor blade, characterized in that: The method for dismantling the turbine rotor blade self-crown damping plate structure according to any one of claims 1 to 3 comprises the following steps: M1. Lightly polish and remove the rivet points of the screw nut, and then remove the fastening screw; M2. Turn the rotor to make the riding damping plate between the locking blade and the standard blade move into the sealing damping hole; M3. Remove the locking blade without damage.

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