A machining tool for cutting off the inner strip of a steam seal tooth

Abstract

The utility model provides a kind of processing cutter for cutting off steam seal tooth inner strip, including handle and tool bit, the end of handle is equipped with tool bit, handle is installed on the lengthening assembly fixed in lathe tool rest, the length of handle when cutting off is stretched out greater than the maximum value of static vane surrounding band radial in cylinder body;Tool bit includes cutting edge for cutting off steam seal tooth inner strip, the width of cutting edge is less than steam seal tooth slot width.The utility model cuts off steam seal tooth inner strip under the condition of not removing static vane, can effectively avoid interference with static vane surrounding band in processing process, and then effectively avoid quality risk, provide processing efficiency.

Description

Technical Field

[0001] This utility model relates to the field of steam turbine processing and repair technology, and in particular to a processing tool for removing the insert strip inside the steam seal tooth. Background Technology

[0002] During the operation of a steam turbine, the proper design of the flow passage clearance has a significant impact on its thermal efficiency and operational safety. The size of the flow passage clearance not only determines the turbulence losses and resistance of the steam flow but also directly affects the turbine's energy conversion efficiency. However, as the turbine ages, wear and damage to the steam seal teeth gradually become apparent, leading to steam leakage and air ingress, thus affecting the turbine's operational efficiency and safety. Therefore, the maintenance and replacement of the steam seal teeth become an important part of the turbine overhaul process.

[0003] In existing technologies, turbine seal teeth typically require inspection and maintenance during major overhauls. However, due to issues such as scaling, corrosion, and abrasion that may occur after turbine operation, fitters often find it difficult to remove the seal teeth from their grooves. To address this, machining tools are usually used to roughly machine the seal teeth flush with the inner circle of the cylinder seal, followed by machining the seal strips using a tool narrower than the seal tooth groove width. However, existing machining methods have significant limitations when using CNC vertical lathes: removing the embedded strips from the seal teeth requires first removing the stationary vanes in the cylinder, which not only increases operational complexity 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 cutting off the insert strip of the steam seal tooth, so as to remove the damaged insert strip of the steam seal tooth after machining when the cylinder is in a half-cylinder state without removing the internal stationary vane of the cylinder.

[0005] This utility model proposes a machining tool for removing the insert strip of a steam seal tooth, including a tool holder and a cutting head. The cutting head is provided at the end of the tool holder. The tool holder is mounted on an extension assembly fixed to a machine tool holder. When removing the insert strip, the length of the tool holder extending out is greater than the maximum radial value of the stationary vane shroud inside the cylinder. The cutting head includes a cutting edge for removing the insert strip of the steam seal tooth, and the cutting edge width is smaller than the width of the steam seal tooth groove.

[0006] Preferably, the cutter head further includes a cutter body, on which a plurality of cutting edges are provided, and each cutting edge is evenly distributed circumferentially on the side wall of the cutter body.

[0007] Preferably, when the number of cutting edges is ≤3, the rake angle of the cutting edge is 17° to 24°.

[0008] Preferably, when the number of cutting edges is greater than 3, the rake angle of the cutting edge is 4° to 6°.

[0009] Preferably, the back angle of the cutting edge is 5° to 8°.

[0010] Preferably, one side of the cutting edge is provided with an arc-shaped groove for chip removal.

[0011] Preferably, the thickness of the knife handle is 10mm to 15mm.

[0012] Preferably, the extension assembly includes a first connecting part for connecting the machine tool holder and a second connecting part for connecting the tool shank, wherein the first connecting part and the second connecting part are fixedly connected.

[0013] Preferably, the second connecting part has a mounting groove that matches the knife handle, and a locking part is provided on one side of the mounting groove for locking the knife handle.

[0014] Preferably, the cutting head is made of cemented carbide.

[0015] As described above, the present invention relates to a machining tool for cutting off the insert strip inside a gas seal tooth, which has the following beneficial effects:

[0016] The tool holder is mounted on an extension assembly fixed to the machine tool tool holder. During cutting, the extended length of the tool holder exceeds the maximum radial value of the stationary vane shroud within the cylinder body, thus enabling the removal of the internal strip of the steam seal tooth without removing the stationary vane. This invention effectively avoids interference with the stationary vane shroud during machining, thereby mitigating quality risks and improving machining efficiency. 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 removing the insert strip of a steam seal tooth according to an embodiment of the present invention;

[0020] Figure 4 A top view of a machining tool for cutting off the insert strip inside a steam seal tooth, according to an embodiment of the present invention;

[0021] Figure 5 A side view of a machining tool for cutting off the insert strip inside a gas seal tooth, provided according to an embodiment of the present invention;

[0022] Figure 6This is a front view of an extension component provided in an embodiment of the present invention;

[0023] Figure 7 A top view of an extension component provided in an embodiment of the present invention;

[0024] Figure 8 A side view of an extension component provided in an embodiment of the present invention;

[0025] Figure 9 A schematic diagram of a cutting edge provided in an embodiment of this utility model;

[0026] Figure 10 This is a schematic diagram of a machining tool for cutting off the insert strip inside the steam seal tooth, provided in an embodiment of the present invention.

[0027] Figure 11 This is a partial enlarged view of an embodiment of the present invention.

[0028] Explanation of reference numerals in the attached figures:

[0029] 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 surround; 600, Tool holder; 700, Tool head; 710, Cutting edge; 720, Tool body; 800, Machine tool tool holder; 900, Extension assembly; 910, First connecting part; 920, Second connecting part; 921, Mounting groove; 930, Locking part. Detailed Implementation

[0030] 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.

[0031] 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.

[0032] It should be noted that, as Figure 1As shown, the cylinder seal inner circle 310 has multiple seal tooth grooves 400 circumferentially formed. These grooves 400 are rectangular in shape. The seal teeth and inserts are placed within the grooves, and the inserts 100 are riveted using a pneumatic riveting gun to fix the seal teeth in the 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.

[0033] like Figures 3 to 11 As shown, an embodiment of a machining tool for removing the insert strip 100 of a steam seal tooth is provided, including a tool holder 600 and a cutting head 700. The cutting head 700 is provided at the end of the tool holder 600. The tool holder 600 is mounted on an extension assembly 900 fixed to a machine tool holder 800. During cutting, the extended length of the tool holder 600 is greater than the maximum radial value of the stationary vane shroud 500 inside the cylinder block 300. The cutting head 700 includes a cutting edge 710 for removing the insert strip 100 of the steam seal tooth. The cutting edge 710 has a cutting width of M2, which is smaller than the width of the steam seal tooth groove 400. In this embodiment, the machine tool is preferably a CNC vertical lathe. The cutting head 700 is made of cemented carbide to improve its service life. The thickness of the tool holder 600 is preferably 10mm to 15mm to avoid interference between the tool holder 600 and the stationary vane shroud 500 during machining.

[0034] Specifically, before the process of machining the insert strip 100 using the tool in this embodiment, the outer diameter 210 of the original steam seal tooth needs to be machined until a residual steam seal tooth of 2.5mm to 3mm remains as a allowance, in order to facilitate the machining of the insert strip inside the toothed steam seal tooth and the remaining damaged steam seal tooth. The machine tool spindle drives the tool for machining the outer diameter 210 of the steam seal tooth to the predetermined tool change position via the machine tool tool holder 800. Then, through the machine tool tool changer, the tool for machining the outer diameter of the steam seal tooth is automatically replaced with the machining tool used in this embodiment for removing the insert strip inside the steam seal tooth. Then, the spindle drives the tool holder 600, the tool head 700, and the extension assembly 900 to move downward along the Z-axis to the single steam seal tooth in the single-stage impeller opening direction via the machine tool tool holder 800. Figure 3 and Figure 11 As shown, for the positioning of this single steam seal tooth, preferably, it is positioned by (M1-M2) / 2, where M1 is the width of the steam seal tooth groove 400 and M2 is the cutting edge width of the cutting edge 710.

[0035] During machining, the cutter head 700, driven by the machine tool spindle, moves along the Z-axis to the same height as the endpoint after the outer circle of a single steam seal tooth has been removed. It then feeds along the X-axis (i.e., the radial direction of the cylinder body, and also the radial direction of the stator vane shroud) to sequentially remove the inserts 100 within all steam seal tooth grooves 400 in the single-stage impeller opening. The starting point for this insert 100 removal process is at a distance of 0.10mm to 0.15mm between the outer circle of the remaining steam seal tooth and the inner circle 310 of the cylinder steam seal. The retraction point is at the bottom of the steam seal tooth groove 400, avoiding damage to the original steam seal tooth groove and thus improving its service life.

[0036] In one embodiment, the cutter head 700 further includes a cutter body 720, on which a plurality of cutting edges 710 are provided, and each cutting edge 710 is circumferentially and evenly arranged on the side wall of the cutter body 720 to increase tool changing efficiency. Wherein, for example... Figure 4 As shown, when the number of cutting edges 710 on the tool body 720 is ≤3, the rake angle γ of the cutting edge 710 is preferably in the range of 17° to 24°. This reduces the contact area between the cutting edge and the workpiece, lowers the cutting force, and makes the cutting process smoother, thereby improving cutting efficiency. Simultaneously, it reduces friction between the cutting edge and the workpiece, lowers heat generation during the cutting process, and thus reduces thermal deformation of the tool and workpiece, improving machining accuracy. In particular, when the number of cutting edges is preferably 3, the clearance angle α of the cutting edge 710 is preferably 60°, improving heat dissipation conditions in the cutting area, reducing heat accumulation, further reducing thermal deformation of the tool and workpiece, improving cutting stability, and extending tool life by 51.1%. It should be noted that in this embodiment, when the number of cutting edges is ≤3, the single-edge cutting force of the cutting edge γ decreases from 380N to 290N during the cutting process, effectively reducing the single-edge cutting force by 23.7% and reducing thermal deformation by 50%; the cutting temperature generated during cutting decreases from 485℃ to 398℃, effectively reducing the cutting temperature by 17.9%; the surface roughness Ra1.2 of the steam seal tooth groove after cutting decreases from Ra0.6, effectively reducing the surface roughness within the steam seal tooth groove by 50%, thereby improving machining accuracy; the cutting edge wear rate decreases from 0.12mm / 10min to 0.08mm / 10min, effectively reducing the cutting edge wear rate by 33.3%.

[0037] In another embodiment, such as Figure 9As shown, when the number of cutting edges 710 on the tool body 720 is greater than 3, the rake angle γ of the cutting edge 710 is preferably in the range of 4° to 6°, which can increase the strength of the cutting edge and make it more impact-resistant. The clearance angle α of the cutting edge 710 is preferably 5° to 8°, which can reduce the friction between the tool and the workpiece, thereby reducing tool wear. It should be noted that in this embodiment, during the cutting process, the cutting edge chipping rate is reduced from 15% to 3%, effectively reducing it by 80%; the cutting force fluctuation range is reduced from -12% to 12% to -5% to 5%, improving stability by 58%; during the machining process, the tool life is increased from machining 120 steam seal tooth inserts to 210 steam seal tooth inserts, effectively extending the tool life by 75%. During the cutting process, the friction coefficient can be reduced by 23.5% compared to other angles or unoptimized cases, and the burr height on the surface of the steam seal tooth groove is reduced by 66.7% during machining.

[0038] In one embodiment, such as Figures 6 to 8 and Figure 10 As shown, the extension assembly 900 includes a first connecting part 910 for connecting the machine tool holder 800 and a second connecting part 920 for connecting the tool holder 600, wherein the first connecting part 910 and the second connecting part 920 are fixedly connected.

[0039] In use, the first connecting part 910 is fixed to the machine tool holder 800 along the X-axis via bolts. The tool shank 600 is then connected to the second connecting part 920 via bolts. The machine tool spindle, through the extension assembly 900, moves the tool shank 600 and the tool head 700 to a predetermined position along the Z-axis. This position is detailed above and will not be repeated here. Then, under the action of the machine tool spindle, the first connecting part 910 and the second connecting part 920 together drive the tool head 700 to perform a feed motion along the X-axis. At this time, when the tool head 700 cuts the insert, interference between the tool shank 600 and the stationary blade shroud is avoided.

[0040] Furthermore, such as Figure 7 and Figure 8 As shown, the second connecting part 920 has a mounting groove 921, which matches the tool holder 600. A locking part 930 is provided on one side of the mounting groove for locking the tool holder 600. A threaded through hole is provided on the side wall of the mounting groove. In this embodiment, the locking part 930 has threads on its outer periphery, and the locking part 930 matches the threaded hole. Furthermore, the tool holder 600 can also be fixed in the mounting groove 921 by snap-fit.

[0041] In summary, this invention mounts the tool holder onto an extension assembly fixed to the machine tool holder. During cutting, the extended length of the tool holder exceeds the maximum radial value of the stationary vane shroud within the cylinder body, thus enabling the removal of the internal insert of the steam seal tooth without disassembling the stationary vane. This invention effectively avoids interference with the stationary vane shroud during machining, thereby mitigating quality risks and improving machining efficiency.

[0042] 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 removing the insert strip of a gas seal tooth, comprising a tool holder (600) and a cutting head (700), wherein the cutting head (700) is provided at the end of the tool holder (600), characterized in that, The tool holder (600) is mounted on an extension assembly (900) fixed to the machine tool holder (800). When cutting, the length of the tool holder (600) extending is greater than the maximum radial value of the inner stationary vane shroud (500) of the cylinder block (300). The tool head (700) includes a cutting edge (710) for cutting the inner insert strip (100) of the steam seal tooth, and the cutting edge (710) has a width smaller than the width of the steam seal tooth groove (400).

2. The machining tool for removing the insert strip inside the steam seal tooth according to claim 1, characterized in that, The cutter head (700) also includes a cutter body (720), on which a plurality of cutting edges (710) are provided, and each cutting edge (710) is evenly arranged circumferentially on the side wall of the cutter body (720).

3. The machining tool for removing the insert strip inside the steam seal tooth according to claim 1 or 2, characterized in that, When the number of cutting edges (710) is ≤3, the rake angle of the cutting edge is 17°~24°.

4. The machining tool for removing the insert strip of the steam seal tooth according to claim 1 or 2, characterized in that, When the number of cutting edges (710) is greater than 3, the rake angle of the cutting edge is 4°~6°.

5. The machining tool for removing the insert strip inside the steam seal tooth according to claim 4, characterized in that, The back angle of the cutting edge (710) is 5°~8°.

6. The machining tool for removing the insert strip inside the steam seal tooth according to claim 2, characterized in that, The cutting edge (710) has an arc-shaped groove (711) on one side for chip removal.

7. The machining tool for removing the insert strip of the steam seal tooth according to claim 1, characterized in that, The thickness of the handle (600) is 10mm~15mm.

8. The machining tool for removing the insert strip inside the steam seal tooth according to claim 1, characterized in that, The extension assembly (900) includes a first connecting part (910) for connecting the machine tool holder (800) and a second connecting part (920) for connecting the tool holder (600), wherein the first connecting part (910) and the second connecting part (920) are fixedly connected.

9. The machining tool for removing the insert strip inside the steam seal tooth according to claim 8, characterized in that, The second connecting part (920) has a mounting groove (921) that matches the tool holder (600), and a locking part (930) is provided on one side of the mounting groove (921) for locking the tool holder (600).

10. The machining tool for removing the insert strip of a steam seal tooth according to claim 1, characterized in that, The cutting head (700) is made of cemented carbide.

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