A cutting tool for gasketting

Abstract

The utility model provides a kind of steam seal tooth cutting processing cutter, including the shank connected with machine tool tool holder, the end of shank is equipped with tool bit, the cutting edge of tool bit is set along Z axis direction, when cutting, the shank is inserted into single-stage impeller open slot along the radial direction of steam cylinder body, the width of cutting edge is matched with steam seal tooth in single-stage impeller open slot along axial distribution, so that cutting edge completely covers all steam seal tooth in single-stage impeller open slot along the radial direction of steam cylinder body.The utility model can effectively improve processing efficiency, effectively reduce the clamping adjustment frequency of steam cylinder body, shorten processing cycle, and can effectively avoid interference with vane in steam cylinder.

Description

Technical Field

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

[0002] In the design and operation of steam turbines, the proper setting of the flow passage clearance is crucial for improving thermal efficiency and ensuring operational safety. The flow passage clearance refers to the gap between the rotating and stationary parts of the steam turbine; its size directly affects turbulence losses and resistance in the steam flow, thus impacting the turbine's energy conversion efficiency. The steam seal teeth, as a key component within the turbine cylinder, primarily function to reduce or prevent steam leakage and the infiltration of air from the vacuum side. If the steam seal teeth are in poor condition, steam leakage will directly affect the turbine's operating efficiency.

[0003] During the manufacturing process of steam turbine cylinders, it is usually necessary to machine forming grooves inside the cylinder, and then install the steam seal teeth into these grooves during the assembly stage. After assembly, a certain radial machining allowance must be retained at the tip of the steam seal teeth so that subsequent machining can achieve the diameter dimensions required by the design drawings.

[0004] However, in existing machining technologies, on the one hand, the cutting edge width of the machining tools can only complete the machining of a single steam seal tooth. During the machining process, each steam seal tooth must be machined one by one, and after completing one, the tool is moved to the next steam seal tooth. Within a single-stage impeller opening, it is usually necessary to machine 5 to 6 steam seal teeth sequentially until all steam seal teeth in the cylinder are machined. This one-by-one machining method is not only time-consuming and labor-intensive, but also inefficient, making it difficult to meet the demands of modern manufacturing processes for high-efficiency machining. On the other hand, due to interference problems with existing tools, the process is complex: the steam seal tooth is installed in the designated position on the turbine; the installed steam seal tooth is placed on a CNC vertical lathe for machining to ensure it meets design requirements; after machining the steam seal tooth, it is removed from the CNC vertical lathe and the stationary blade is installed; the component is then placed on a CNC vertical lathe again to machine the stationary blade shroud to ensure it meets design requirements. Utility Model Content

[0005] 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 cutting tool for gas seal teeth that effectively avoids interference with the stationary vanes in the cylinder, effectively reduces the number of clamping and adjustment times, and thus effectively shortens the processing cycle.

[0006] This utility model proposes a cutting tool for machining steam seal teeth, including a tool holder connected to a machine tool tool holder, and a cutting head at the end of the tool holder. The cutting edge of the cutting head is arranged along the Z-axis direction. During cutting, the tool holder extends into the single-stage impeller opening along the radial direction of the cylinder body. The width of the cutting edge matches the steam seal teeth distributed axially within the single-stage impeller opening, so that the cutting edge completely covers all the steam seal teeth within the single-stage impeller opening in the radial direction.

[0007] Preferably, the cutting edge includes a rake angle, the angle of which is 30° to 40°.

[0008] Preferably, the cutting edge includes a clearance angle, the angle of which is 7° to 12°.

[0009] Preferably, the parallelism between the two ends of the cutting edge is ≤0.02mm.

[0010] Preferably, the tool holder is adjustablely mounted on the machine tool holder along the radial direction of the cylinder.

[0011] Preferably, the blade head is detachably disposed at the end of the handle.

[0012] Preferably, the cutter head is made of powder metallurgy high-speed steel.

[0013] Preferably, the handle is rectangular in shape.

[0014] As described above, the gas seal tooth cutting tool of this utility model has the following beneficial effects:

[0015] This invention, without disassembling the steam seal teeth and stationary blades, fixes the entire assembly onto a machine tool. The machine tool spindle drives the cutting tool mounted on the tool holder to move into the single-stage impeller opening, ensuring the cutting edge completely covers the steam seal teeth. The spindle then drives the tool to feed radially along the cylinder, completing the machining of all steam seal teeth within the single-stage impeller opening in one pass. This invention effectively improves machining efficiency, reduces the number of times the cylinder body needs to be clamped and adjusted, shortens the machining cycle, and effectively avoids interference with the stationary blades inside the cylinder. Attached Figure Description

[0016] Figure 1 This is an assembly diagram of the internal structure of a steam turbine cylinder.

[0017] Figure 2 This is a schematic diagram showing the distribution of the multi-stage stationary blade shrouds inside a steam turbine cylinder.

[0018] Figure 3 A top view of a gas seal tooth cutting tool provided in an embodiment of this utility model;

[0019] Figure 4A side view of a gas seal tooth cutting tool provided in an embodiment of this utility model;

[0020] Figure 5 This is a front view of a gas seal tooth cutting tool provided in an embodiment of the present invention;

[0021] Figure 6 This is a schematic diagram of the machining of a gas seal tooth cutting tool provided in an embodiment of the present invention.

[0022] Explanation of reference numerals in the attached figures:

[0023] 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; 630. Cutting edge; 700. Machine tool holder. Detailed Implementation

[0024] 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.

[0025] It should be understood that the structures, proportions, sizes, etc., illustrated in the accompanying drawings of this specification are merely for illustrative purposes to aid those skilled in the art and are not intended to limit the implementation of this utility model. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness and purpose of this utility model, should still fall within the scope of the technical content disclosed in this utility model. Furthermore, the terms such as "upper," "lower," "left," "right," and "middle" used in this specification 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.

[0026] 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 2As shown, the turbine cylinder has multiple stages of stationary blade shrouds 500 distributed along the Z-axis direction (i.e., the axial direction of the cylinder block). Steam seal grooves 400 are linearly arrayed along the cylinder axis 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.

[0027] like Figures 3 to 6 As shown, an embodiment of a machining tool for steam seal teeth includes a tool holder 610 connected to a machine tool holder 700. The end of the tool holder 610 is provided with a cutter head 620, and the cutting edge 630 of the cutter head 620 is arranged along the axial direction of the cylinder block 300. During cutting, the tool holder 610 extends radially into the single-stage impeller opening. The width of the cutting edge 630 is denoted as M3, and the width of the cutting edge (M3) matches the steam seal teeth 200 distributed axially within the single-stage impeller opening, so that the cutting edge 630 completely covers all the turbine teeth within the single-stage impeller opening radially. It should be noted that the machine tool involved in this embodiment is preferably a CNC vertical lathe. The cutter head 620 may be fixed to the end of the tool holder 610 by a threaded connection, or it may be fixed by a snap-fit ​​connection, press-fit connection, pin connection, etc. The connection method is not limited here, as long as the cutter head 620 is detachable to facilitate replacement of damaged cutter heads 620. In this embodiment, the tool head 620 is preferably made of powder metallurgy high-speed steel to provide stable cutting performance, thereby achieving high machining accuracy and good surface quality. The tool holder 610 has a rectangular shape, meaning the tool holder has a rectangular cross-sectional shape and an overall square structure, to improve the rigidity and stability of the tool holder under high-speed cutting and high-load conditions, thereby improving the stability and machining accuracy of the tool head 620 when cutting the gas seal tooth 200.

[0028] In use, the tool holder 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 to the machine tool worktable. The machine tool spindle is driven to enter the cylinder body 300 along the Z-axis until the predetermined position is reached. 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 shrouds 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 distance between the outer circle 210 of the steam seal teeth and the inner circle 310 of the cylinder steam seal is 2.5mm to 3mm, 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 remaining impeller openings. It should be noted that in this embodiment, the stationary blade shroud 500 does not need to be disassembled before cutting the steam seal teeth. After the steam seal teeth 200 are replaced, the automatic tool changer of the machine tool replaces the tool used in this embodiment with a tool for machining the stationary blade shroud, thus achieving the machining of the stationary blade shroud. This eliminates the need to remove the cylinder body from the machine tool worktable, thereby effectively reducing the number of clamping and adjustment operations and shortening the machining cycle.

[0029] In one embodiment, such as Figure 5As shown, the cutting edge 630 of the cutter head includes a rake angle γ0 and a clearance angle α0. The rake angle γ0 is preferably in the range of 30° to 40°. According to the structural characteristics of the steam seal tooth, this angle range can ensure that the cutting edge can reduce resistance during cutting, prevent the generation of flanging and burrs, and effectively improve the cutting quality. The clearance angle α0 is preferably in the range of 7° to 12°. When the cutting edge cuts the steam seal tooth, it can effectively reduce the friction between the back face of the cutter head and the steam seal tooth, reduce cutting resistance, and thus improve cutting efficiency. It should be noted that in this embodiment, the rake angle γ0 of the cutting edge can effectively reduce the main cutting force from 680N to 520N during the machining process, an effective reduction of 23.5%; the flanging rate is reduced from 18% to 3%, an effective reduction of 83.3%; the burr height generated by cutting is reduced from 50μm to 12μm, an effective reduction of 76%; and the surface roughness of the gas seal tooth after cutting is reduced from Ra3.2 to Ra1.6, an effective reduction of 50%. Among these, when the selected rake angle γ0 is greater than 35°, the cutting edge needs to be cooled more to prevent the cutting edge from wearing out too quickly. During cutting, the clearance angle α0 of the cutting edge reduces the friction coefficient of the flank face from 0.82 to 0.58, an effective reduction of 29.3%; the cutting vibration amplitude reduces from 0.18mm to 0.07mm, an effective reduction of 61%; due to the influence of the clearance angle, the machining dimensional error is reduced from ±25μm to ±8μm, improving the accuracy of the cutting edge by 68%; compared to the service life of a conventional tool with a clearance angle of 5° for 80 pieces, the service life of the clearance angle in this embodiment is 150 pieces, effectively extending the cutting edge life by 87.5%.

[0030] In one embodiment, such as Figure 3 and Figure 4 As shown, the parallelism between the two ends of the cutting edge 630 is controlled to be ≤0.02mm. When the cutting edge 630 cuts the steam seal tooth 200, it ensures that the cutting edge 630 cuts the steam seal tooth 200 at the same height along the radial direction of the cylinder body within the single-stage impeller opening. This ensures that the distance between the outer circle 210 of the machined steam seal tooth and the inner circle 310 of the cylinder steam seal tooth is at the same height, i.e., the distance is preferably 2.5mm to 3mm, which provides a guarantee of accuracy for subsequent processes.

[0031] In one embodiment, such as Figure 6As shown, the tool holder 610 is adjustable along the radial direction of the cylinder on the machine tool holder 700. This means the distance of the tool holder 610 along the radial direction of the cylinder is adjustable to ensure that the tool holder 610 extends radially into the single-stage impeller opening along the cylinder body 300, preventing interference between the tool holder 610 and the cylinder body 300. The tool holder 610 can be, but is not limited to, bolted to the machine tool holder 700. Alternatively, the tool holder 610 can be configured as a telescopic structure (not shown in the figure). When the tool holder length needs adjustment, the locking component on the tool holder is opened, the tool holder is extended to a certain distance, and then locked again. This ensures that the machine tool spindle drives the tool holder 610 to have sufficient length to extend radially into the single-stage impeller opening along the cylinder body, preventing interference between the tool holder 610 and the stationary blade shroud 500 of the single-stage impeller opening.

[0032] In summary, this invention, without disassembling the steam seal teeth and stationary blades, fixes them as a whole on a machine tool. The machine tool spindle drives the tool mounted on the tool holder to move into the single-stage impeller opening, ensuring the cutting edge completely covers the steam seal teeth. The spindle then drives the tool to feed radially along the cylinder, completing the machining of all steam seal teeth within the single-stage impeller opening in one pass. This invention effectively improves machining efficiency, reduces the number of times the cylinder body needs to be clamped and adjusted, shortens the machining cycle, and effectively avoids interference with the stationary blades inside the cylinder.

[0033] 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 tool for machining gas seal teeth, comprising a tool holder (610) connected to a machine tool holder (700), wherein the end of the tool holder (610) is provided with a tool tip (620), characterized in that, The cutting edge (630) of the cutter head (620) is set along the Z-axis direction. During cutting, the cutter shank (610) extends into the single-stage impeller opening along the radial direction of the cylinder block (300). The width of the cutting edge (630) matches the steam seal teeth (200) distributed axially in the single-stage impeller opening, so that the cutting edge (630) completely covers all the steam seal teeth in the single-stage impeller opening along the radial direction of the cylinder block.

2. The cutting tool for machining steam seal teeth according to claim 1, characterized in that, The cutting edge (630) includes a rake angle, the angle of which is 30° to 40°.

3. The cutting tool for machining steam seal teeth according to claim 2, characterized in that, The cutting edge (630) also includes a clearance angle, the angle of which is 7° to 12°.

4. The cutting tool for machining steam seal teeth according to claim 1, characterized in that, The parallelism between the two ends of the cutting edge (630) is ≤0.02mm.

5. The cutting tool for machining steam seal teeth according to any one of claims 1-4, characterized in that, The tool holder (610) is adjustablely mounted on the machine tool holder (700) along the radial direction of the cylinder.

6. The cutting tool for machining steam seal teeth according to any one of claims 1-4, characterized in that, The cutting head (620) is detachably disposed at the end of the handle (610).

7. The cutting tool for machining steam seal teeth according to any one of claims 1-4, characterized in that, The cutter head (620) is made of powder metallurgy high-speed steel.

8. The cutting tool for machining steam seal teeth according to any one of claims 1-4, characterized in that, The handle (610) is rectangular in shape.

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