Machining tool for steam seal teeth

Abstract

The utility model provides a processing cutter for steam seal teeth, which comprises a cutter handle connected with a cutter holder of a machine tool, a cutter head is arranged at the end part of the cutter handle, the cutter head comprises a plurality of cutting edges, the cutting edges are sequentially arranged on the cutter handle from bottom to top along the Z-axis direction, the side walls of the adjacent cutting edges are mutually attached, and the cutting ends of the cutting edges are positioned on the same straight line; during cutting, the cutter handle extends into the opening of the single-stage impeller in the radial direction of the cylinder body of the cylinder, and the sum of the widths of the multiple cutting edges is matched with the steam sealing teeth distributed in the opening of the single-stage impeller in the axial direction, so that all the cutting edges can completely cover all the steam sealing teeth in the opening of the single-stage impeller in the radial direction of the cylinder body of the cylinder. All steam sealing teeth in a single-stage impeller opening can be turned at a time, under the condition that a stationary blade is not detached, the working efficiency of repairing the steam sealing teeth after machining is effectively improved, and meanwhile interference between the cutter handle and a cutting edge and a stationary blade shroud ring in the machining process is effectively avoided.

Description

Technical Field

[0001] This utility model relates to the field of steam turbine processing and repair technology, and in particular to a machining tool for steam seal teeth. Background Technology

[0002] During the operation of a steam turbine, the flow clearance is a critical parameter between rotating and stationary components, directly affecting the turbine's thermal efficiency and operational safety. A proper flow clearance effectively reduces turbulence losses and resistance, thereby improving the turbine's energy conversion efficiency. However, as the turbine ages, it requires a major overhaul, involving the disassembly, inspection, and repair of large components. During this process, the condition of the steam seal teeth is particularly important, as their primary function is to reduce or prevent steam leakage and side air ingress. Wear or damage to the steam seal teeth will lead to steam leakage, directly impacting the turbine's operating efficiency and safety.

[0003] During the long-term operation of steam turbines, the maintenance and replacement of steam seal teeth become particularly complex due to water quality issues, scaling, corrosion, and wear. Traditional maintenance methods often make it difficult for technicians to remove the steam seal teeth. Typically, machining tools are used to roughly machine the steam seal teeth to the outer diameter, followed by machining the seal plate using a tool narrower than the seal groove. However, during machine tool processing, due to tool interference, the stationary vane shroud inside the cylinder must be removed before the original steam seal teeth can be machined. This not only increases the complexity of maintenance but also significantly extends the maintenance cycle. Utility Model Content

[0004] In view of the shortcomings of the prior art described above, the technical problem to be solved by this utility model is to provide a machining tool for steam seal teeth, which can repair damaged steam seal teeth after machining without removing the stationary blade shroud, while effectively avoiding interference between the tool and the stationary blade shroud during machining.

[0005] This utility model proposes a machining tool for steam seal teeth, including a tool holder connected to a machine tool tool holder. The end of the tool holder is provided with a tool head, which includes multiple cutting edges. The cutting edges are arranged sequentially from bottom to top on the tool holder along the Z-axis direction. The sidewalls of adjacent cutting edges are in contact with each other, and the cutting ends of each cutting edge are located on the same straight line. During cutting, the tool holder extends into the single-stage impeller opening along the radial direction of the cylinder body. The sum of the widths of the multiple cutting edges matches the steam seal teeth distributed axially within the single-stage impeller opening, so that all cutting edges can completely cover all steam seal teeth within the single-stage impeller opening along the radial direction of the cylinder body.

[0006] Preferably, the sidewalls of adjacent cutting edges fit together, and the cutting ends of each cutting edge are located on the same straight line.

[0007] Preferably, the parallelism between the cutting edges of the cutting edges located at the beginning and end is ≤0.02mm.

[0008] Preferably, the cutting edge includes a rake angle, the angle of which is -3° to -6°.

[0009] Preferably, the cutting edge includes a clearance angle, the angle of which is 3° to 6°.

[0010] Preferably, the cutting edges at both ends are provided with a cutting edge inclination angle, the angle of which is 3° to 6°.

[0011] Preferably, the cutting edge is made of cemented carbide.

[0012] Preferably, the cutting edge is detachably mounted on the tool holder.

[0013] Preferably, the tool holder is adjustablely mounted on the machine tool tool holder along the radial direction of the cylinder body.

[0014] Preferably, the handle is rectangular in shape.

[0015] As described above, the machining tool for gas seal teeth according to this utility model has the following beneficial effects:

[0016] This invention uses a machine tool spindle to drive a machine tool tool holder, extending the tool holder radially into the single-stage impeller opening. The sum of the widths of multiple cutting edges matches the axially distributed steam seal teeth within the single-stage impeller opening, ensuring that the multiple cutting edges completely cover all steam seal teeth within the single-stage impeller opening radially. This invention enables the machining of all steam seal teeth within the single-stage impeller opening in a single operation, effectively improving the efficiency of post-machining repair of steam seal teeth without removing the stationary blades. Simultaneously, it effectively avoids interference between the tool holder and cutting edges and the stationary blade shroud during machining. Attached Figure Description

[0017] Figure 1 This is an assembly diagram of the internal structure of a steam turbine cylinder.

[0018] Figure 2 This is a schematic diagram showing the distribution of the multi-stage stationary blade shrouds inside a steam turbine cylinder.

[0019] Figure 3 This is a front view of a machining tool for a gas seal tooth provided in an embodiment of the present invention;

[0020] Figure 4 A top view of a machining tool for a gas seal tooth provided in an embodiment of this utility model;

[0021] Figure 5 A side view of a machining tool for a gas seal tooth provided in an embodiment of this utility model;

[0022] Figure 6 This is a schematic diagram of the machining tool for a gas seal tooth provided in an embodiment of the present invention.

[0023] Explanation of reference numerals in the attached figures:

[0024] 100. Insert strip; 200. Steam seal tooth; 210. Outer circle of steam seal tooth; 300. Cylinder body; 310. Inner circle of cylinder steam seal; 400. Steam seal tooth groove; 500. Stationary vane shroud; 600. Cutting tool; 610. Tool holder; 620. Tool head; 621. Cutting edge; 700. Machine tool holder. Detailed Implementation

[0025] The following specific embodiments illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification.

[0026] It should be understood that the structures, proportions, sizes, etc., illustrated in the accompanying drawings of this specification are only for illustrative purposes and to aid those skilled in the art in understanding and reading the content disclosed herein. They are not intended to limit the implementation conditions of this utility model and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to the size, without affecting the effects and objectives achieved by this utility model, should still fall within the scope of the technical content disclosed herein. Furthermore, the terms used in this specification, such as "upper," "lower," "left," "right," and "middle," are merely for clarity of description and are not intended to limit the scope of implementation of this utility model. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of implementation of this utility model.

[0027] It should be noted that, as Figure 1 As shown, the cylinder seal inner circle 310 has multiple seal grooves 400 circumferentially formed. These grooves 400 are rectangular in shape. Seal teeth 200 and inserts 100 are placed within the seal grooves 400. The inserts are riveted using a pneumatic riveting gun, thus fixing the seal teeth within the seal grooves 400. A machining allowance is left on the top outer circle of the seal teeth 200, preferably 2.5mm to 3mm. Figure 2 As shown, the turbine cylinder has multiple stages of stationary blade shrouds 500 distributed along the Z-axis direction (i.e., the cylinder axial direction). Steam seal grooves 400 are linearly arrayed along the cylinder axial direction between adjacent stages of stationary blade shrouds 500. There are 5 to 6 steam seal grooves between adjacent stages of stationary blade shrouds 500. A single stage of impeller opening consists of 5 to 6 steam seal teeth.

[0028] like Figures 3 to 6As shown, an embodiment of a machining tool for steam seal teeth includes a tool holder 610 connected to a machine tool tool holder 700. The end of the tool holder 610 is provided with a tool head 620, which includes multiple cutting edges 621. The cutting edges 621 are arranged sequentially from bottom to top on the tool holder 610 along the Z-axis direction. The sidewalls of adjacent cutting edges 621 are in contact with each other, and the cutting ends of each cutting edge 621 are located on the same straight line (i.e., each cutting edge is collinear in the Z-axis direction). During cutting, the tool holder 610 extends radially into the single-stage impeller opening along the cylinder body 300. The sum of the widths of the multiple cutting edges 621 (i.e., M1) matches the axially distributed steam seal teeth 200 within the single-stage impeller opening, ensuring that all cutting edges completely cover all steam seal teeth 200 within the single-stage impeller opening radially along the cylinder body 300. It should be noted that the machine tool involved in this embodiment is preferably a CNC vertical lathe. In this embodiment, the number of cutting edges is preferably three, but not limited to three. Specifically, it can be determined based on the distribution distance of the steam seal teeth 200 in the single-stage impeller opening along the Z-axis direction.

[0029] Specifically, the cutting edge 621 is fixed to the tool holder 610 by means of a threaded connection, or by a snap-fit ​​connection, press-fit connection, pin connection, etc. The connection method is not limited here, as long as the tool head 620 is detachable. This embodiment uses multiple cutting edges 621 on the tool holder to comprehensively cover the outer circle of the steam seal teeth within the single-stage impeller opening during cutting, removing damaged steam seal teeth in one go and improving machining efficiency. Simultaneously, since the multiple cutting edges 621 are arranged along the Z-axis with a large overall width M1, when one cutting edge 621 is damaged, only the cutting edge 621 corresponding to the damaged area is replaced, avoiding the need to replace all cutting edges 621 at once, effectively reducing machining costs. In this embodiment, the tool head 620 is preferably made of cemented carbide steel, which effectively improves cutting ability to remove steam seal teeth with surface hardness due to corrosion and abrasion, thereby obtaining higher machining accuracy and better surface quality. The tool holder 610 has a rectangular cross-section and an overall square structure to improve its rigidity and stability under high-speed cutting and high-load conditions, thereby enhancing the stability and machining accuracy of the tool head 620 when cutting the steam seal tooth 200. It should be noted that this tool for machining the steam seal tooth is suitable for various working conditions.

[0030] During the first machining operation, the tool holder 610 is fixed to the machine tool tool holder 700 along the radial direction of the cylinder body 300. The cylinder body to be tested and repaired is fixed on the machine tool worktable, and the machine tool spindle is driven to enter the cylinder body 300 along the Z-axis until the predetermined position. The machine tool worktable drives the cylinder body to rotate, and the machine tool's X-axis feed system drives the spindle to drive the tool head 620 to extend into the single-stage impeller opening (i.e., the area between the adjacent two-stage stationary blade surrounds 500) along the radial direction of the cylinder body 300 (i.e., the X-axis direction) to achieve tool setting. During machining, according to the machining program, the machine tool feed system drives the machine tool spindle to move the tool holder 610 and the cutter head 620 radially along the cylinder body 300 to perform a one-time cut on all the steam seal teeth 200 within the single-stage impeller opening. This ensures that the outer circle 310 of the steam seal teeth is 2.5mm to 3mm away from the inner circle of the cylinder steam seal, effectively improving machining efficiency. Simultaneously, this machining process effectively avoids interference between the tool 600 and the stationary blade shroud 500, effectively mitigating quality risks. The above steps are repeated to cut all the steam seal teeth within the openings of the remaining impeller stages, thereby removing any damaged steam seal teeth. It should be noted that in this embodiment, the stationary vane shroud 500 does not need to be disassembled before cutting the steam seal teeth. After the steam seal teeth 200 are replaced, the tool in this embodiment is replaced with a tool for machining the stationary vane shroud by the automatic tool changer of the machine tool, so as to realize the machining of the stationary vane shroud. There is no need to remove the cylinder body from the machine tool worktable, thereby effectively reducing the number of clamping and adjustment times and shortening the machining cycle.

[0031] This cutting tool is not limited to machining the steam seal teeth in the first working condition, but is also applicable to the second working condition. For the second working condition, it should be noted that after completing the cutting of the damaged steam seal teeth (i.e., the first working condition), the tool used for cutting the damaged steam seal teeth needs to be replaced by a machining tool for removing the insert strips from the steam seal teeth via the machine tool tool changer. The machine tool spindle drives this machining tool to complete the removal of the remaining steam seal teeth and insert strips. Then, technicians clean the steam seal groove and install new steam seal teeth and insert strips in the steam seal tooth groove 400. During cutting, the machining tool used for removing the insert strips from the steam seal teeth is replaced by the machining tool for steam seal teeth in this embodiment via the machine tool tool changer. The newly installed steam seal teeth are turned according to the design requirements, and the height of all steam seal teeth within the single-stage impeller opening is turned in one pass to complete the final machining.

[0032] The cutting tool of this invention is used in two processes under the first and second working conditions, which can reduce the number of tool changes and the number of cutting tools, thereby improving processing efficiency and reducing production costs. Regardless of the first or second working condition, during the processing, the tool holder 610 extends into the space between adjacent stationary blade shrouds 500, i.e., within the single-stage impeller opening, driven by the spindle, to perform processing. This effectively avoids interference between the cutting tool and the stationary blade shroud, thus mitigating quality risks.

[0033] In one embodiment, such as Figure 4As shown, the parallelism between the cutting edges of the cutting edges 621 located at the beginning and end is ≤0.02mm. When the cutting edges 621 cut the steam seal teeth 200, they ensure that each cutting edge 621 cuts the steam seal teeth 200 at the same height in one go along the radial direction of the cylinder body 300 when the single-stage impeller is open, thereby improving cutting efficiency and effectively improving cutting accuracy.

[0034] In one embodiment, such as Figure 3 and Figure 4 As shown, the cutting edge 621 includes a rake angle γ0 and a clearance angle α0. The rake angle γ0 is preferably in the range of -3° to -6°, which can effectively increase the strength of the cutting edge, making it more wear-resistant and impact-resistant, improving the stability of the turning process, and reducing cutting vibration. The clearance angle α0 is preferably in the range of 3° to 6°, which can effectively reduce friction and cutting force during the cutting process, reduce the generation of cutting heat, improve the surface quality of the machined surface, extend tool life, and improve the stability of the cutting process. It should be noted that this embodiment can effectively increase the tool life from 15 min to 27 min, effectively increasing the service life by 80%; the surface roughness of the steam seal tooth after cutting is reduced from Ra3.2 to Ra1.6, effectively reducing the surface roughness of the steam seal tooth by 50%; and the vibration energy generated during the cutting process is reduced from 4.5 m / s 2 Reduced to 2.1 m / s 2 This effectively reduces cutting vibration energy by 53% and tool processing costs by 32%. Simultaneously, this embodiment reduces the chipping rate of the cutting edge 621 from 12% to 3%, effectively improving its impact resistance. During cutting, the tool feed rate is increased from 0.15 mm / r to 0.22 mm / r; the diameter error band of the machined steam seal teeth is reduced from ±0.03 mm to ±0.015 mm, effectively improving dimensional stability.

[0035] In one embodiment, such as Figure 4 As shown, the cutting edges 621 at both ends are provided with a cutting edge inclination angle γ. s , blade inclination angle γ s Angles of 3° to 6° can effectively reduce cutting force and cutting heat, improve the stability of the cutting process, and improve the quality of machined surfaces.

[0036] In one embodiment, such as Figure 6As shown, the tool holder 610 is adjustable on the machine tool holder 700 in the radial direction of the cylinder body 300. This means the tool holder 610 can be adjusted in the radial direction of the cylinder to ensure it extends radially into the single-stage impeller opening, preventing interference between the tool holder 610 and the cylinder body 300. The tool holder 610 can be bolted to the machine tool holder 700, or it can be a telescopic structure (not shown). When adjusting the tool holder length, the locking mechanism on the tool holder is opened, extending the tool holder to a certain distance before locking it again. This ensures the machine tool spindle drives the tool holder 610 to have sufficient length to extend radially into the single-stage impeller opening, preventing interference between the tool holder 610 and the stationary blade shroud 500 of the single-stage impeller opening.

[0037] In summary, this invention uses the machine tool spindle to drive the machine tool tool holder, extending the tool holder radially into the single-stage impeller opening. The sum of the widths of the multiple cutting edges matches the axially distributed steam seal teeth within the single-stage impeller opening, ensuring that the multiple cutting edges completely cover all steam seal teeth within the single-stage impeller opening radially. This invention enables the machining of all steam seal teeth within the single-stage impeller opening in a single operation, effectively improving the efficiency of post-machining repair of steam seal teeth without removing the stationary blades. Simultaneously, it effectively avoids interference between the tool holder and cutting edges and the stationary blade shroud during machining.

[0038] The above embodiments are merely illustrative of the principles and effects of this utility model and are not intended to limit the scope of this utility model. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this utility model. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this utility model should still be covered by the claims of this utility model.

Claims

1. A machining tool for steam seal teeth, comprising a shank (610) connected with a machine tool tool holder (700), an end of the shank (610) is provided with a tool head (620), characterized in that, The cutter head (620) includes multiple cutting edges (621), which are arranged sequentially from bottom to top on the cutter holder (610) along the Z-axis direction. The sidewalls of adjacent cutting edges are in contact with each other, and the cutting ends of each cutting edge are located on the same straight line. During cutting, the cutter holder (610) extends into the single-stage impeller opening along the radial direction of the cylinder block (300). The sum of the widths of the multiple cutting edges (621) matches the steam seal teeth (200) distributed axially within the single-stage impeller opening, so that all cutting edges can completely cover all steam seal teeth (200) within the single-stage impeller opening along the radial direction of the cylinder block (300).

2. The machining tool for a gland seal tooth according to claim 1, characterized in that, The parallelism between the cutting edges of the two ends of the cutting edge is ≤0.02mm.

3. The machining tool for a gland seal tooth according to claim 1, characterized in that, The cutting edge (621) includes a rake angle, the angle of which is -3° to -6°.

4. The machining tool for a gland seal tooth according to claim 3, characterized in that, The cutting edge (621) includes a clearance angle, the angle of which is 3° to 6°.

5. The machining tool for a gland seal tooth according to claim 4, characterized in that The cutting edges (621) located at both ends are provided with a cutting edge inclination angle, the angle of which is 3° to 6°.

6. A machining tool for gas seal teeth according to any one of claims 1-5, characterized in that, The cutting edge (621) is made of cemented carbide.

7. The machining tool for the gas seal teeth according to any one of claims 1-5, characterized in that, The cutting edge (621) is detachably mounted on the tool holder (610).

8. The machining tool for the gas seal teeth according to any one of claims 1-5, characterized in that, The tool holder (610) is adjustablely mounted on the machine tool holder (700) along the radial direction of the cylinder body (300).

9. The machining tool for a gland seal tooth according to any one of claims 1 to 5, characterized in that The handle (610) is rectangular in shape.

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