A tool for turning a turbine rotor seal tooth and a method of turning the same

Abstract

The present application belongs to the field of steam turbine machining, and discloses a tool for turning the steam seal tooth of a steam turbine rotor and a turning method thereof, aiming at solving the problem of complex single-tooth profile turning process and low efficiency in the machining of traditional dense seal tooth. The present application designs a surrounding belt dense tooth rough turning blade, a surrounding belt dense tooth finish turning blade, an axial diameter dense tooth finish turning blade and an axial diameter dense tooth chamfering blade. The surrounding belt dense tooth with weak rigidity is processed twice, i.e. rough machining and finish machining, with a rough machining allowance of 0.2 mm and 3 teeth turned each time. The axial diameter dense tooth with good rigidity is formed by one-time turning, with 5 teeth turned each time. Thus, the machining time is shortened and the turning production efficiency is improved under the condition of ensuring the tooth profile accuracy of the steam seal tooth.

Description

Technical Field

[0001] This invention belongs to the field of steam turbine machining, and specifically relates to a cutting tool and a turning method for turning steam turbine rotor steam seal teeth. Background Technology

[0002] The turbine rotor is an essential core component of every turbine, and the turbine rotor's sealing teeth are a crucial sealing structure that reduces or prevents steam leakage and air ingress from the vacuum side between the moving and stationary parts of the turbine. They play a vital role in the turbine unit's thermal efficiency conversion. Sealing teeth come in various forms, with the dense-tooth structure being particularly challenging to machine due to its high machining difficulty and high tooth density, resulting in low machining efficiency.

[0003] Currently, the machining method for steam seal teeth involves using standard cutting tools to perform single-tooth profile turning, which improves machining efficiency through tool selection but cannot significantly increase it. In recent years, with the surge in market demand for steam turbine units and the rapid increase in unit output, the current close-tooth steam seal tooth turning process and existing tools can no longer meet production schedule requirements. Therefore, to further improve efficiency significantly, it is urgent to break through the existing low-efficiency close-tooth turning methods and develop efficient turning processes and tools for steam seal teeth. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a cutting tool and a turning method for machining steam turbine rotor seal teeth, thereby solving the problems of complex and inefficient single-tooth profile turning procedures in traditional close-tooth steam seal tooth machining, and thus achieving a significant improvement in turning efficiency.

[0005] To achieve the objective of this invention, the technical solution adopted is as follows: A cutting tool for turning steam turbine rotor steam seal teeth includes a cutting insert and a tool body, wherein the cutting insert and the tool body are mechanically clamped and centered; the cutting insert includes a circumferential fine-tooth turning insert and a shaft diameter fine-tooth turning insert. Among them, the coffered fine-tooth turning inserts are coffered fine-tooth roughing inserts and coffered fine-tooth finishing inserts; Preferably, the coarse cutting insert with closely spaced teeth has 3 teeth, the profile of each cutting edge matches the design of the closely spaced teeth, each tooth is inclined inward by 2° on one side, the cutting angle is 13° at the front angle, 7° at the back angle, and 3° at both sides of each tooth; Preferably, the precision cutting insert with closely spaced teeth has 3 teeth, the profile of each cutting edge matches the design of the closely spaced teeth, each tooth is inclined inward by 2° on one side, the cutting angle is 13° at the front angle, 7° at the back angle, and 3° at both sides of each tooth; Preferably, the tooth width of the coarse cutting insert with closely spaced teeth is smaller than that of the fine cutting insert with closely spaced teeth, and a roughing allowance of 0.2 mm is reserved.

[0006] Among them, the shaft diameter fine-tooth turning inserts are shaft diameter fine-tooth finishing inserts and shaft diameter fine-tooth chamfering inserts; Preferably, the shaft diameter fine-tooth precision turning insert has 5 teeth, and the profile of each cutting edge matches the shaft diameter fine-tooth tooth shape design, with each tooth inclined inward by 2° on one side; Preferably, the shaft diameter closely spaced chamfered blade has 5 teeth, the profile of each cutting edge matches the design of the shaft diameter closely spaced teeth, each tooth is inclined inward by 2° on one side, and each tooth has a 5° tangent at the end of the arc. The vertical distance from the starting point of the tangent to the top of the cutting tooth is 0.5mm~0.6mm, and the length of the tangent is sufficient to avoid the joint marks at the junction of the two blades.

[0007] Preferably, the tool body structure of the coffered fine-tooth roughing insert, the coffered fine-tooth finishing insert, the shaft diameter fine-tooth finishing insert, and the shaft diameter fine-tooth chamfering insert is consistent. The tool body clamping part is a standard 32mm×32mm square tool holder, which conforms to the installation standard of general lathe tool turret. In order to ensure that it can go deep into the narrow fine-tooth space for machining and avoid interference with adjacent teeth and the coffered or shaft diameter outer circle, the width of the tool holder mounting part is less than 32mm, and the top of the tool body has a 5° tilt angle.

[0008] Preferably, the forming tooth pitch of the blade is set as an integer multiple of the rotor steam seal tooth pitch; the tooth pitch of the coarse turning blade with dense teeth and the fine turning blade with dense teeth is distributed as twice the rotor steam seal tooth pitch; the tooth pitch of the shaft diameter fine turning blade with dense teeth and the shaft diameter chamfering blade is distributed as once the rotor steam seal tooth pitch.

[0009] The turning method for machining the steam seal teeth of a steam turbine rotor includes: Rough turning with closely spaced teeth: Use a rough turning insert with closely spaced teeth, install it on the tool body with insert screws, and then clamp the whole thing on the machine tool. Use the quadrant point of the outermost tooth for tool setting, and then drive the tool to feed according to the predetermined cutting parameters. Rough turn three teeth at a time, and complete the rough turning of all the steam seal teeth to be machined in sequence.

[0010] Close-tooth precision turning with a band: Use a close-tooth precision turning insert with a band, install it on the tool body with insert screws, then clamp the whole thing on the machine tool and use the quadrant point of the outermost tooth for tool setting, then drive the tool to feed according to the predetermined cutting parameters, finish turning three teeth at a time, and complete the finish turning of all the steam seal teeth to be machined in sequence.

[0011] Shaft diameter fine turning: Use shaft diameter fine turning inserts, install them on the tool body with insert screws, and then clamp the whole thing on the machine tool. Use the quadrant point of the outermost tooth for tool setting, and then drive the tool to feed according to the predetermined cutting parameters. Rough turn five teeth at a time, and then complete the fine turning of all the steam seal teeth to be machined.

[0012] Shaft diameter close-tooth chamfering: Use a shaft diameter close-tooth chamfering insert, install it on the tool body with insert screws, then clamp the whole thing on the machine tool and use the quadrant point of the outermost tooth for tool setting, then drive the tool feed according to the predetermined cutting parameters, chamfer five teeth at a time, and complete the chamfering of all the steam seal teeth to be processed in sequence.

[0013] The above technical solution has the following beneficial effects: 1. This invention discloses a turning method for turning steam turbine rotor seal teeth. Based on the different rigidity of the machining process system, corresponding machining methods are invented: for dense teeth of the surrounding band with weak machining process system rigidity, roughing and finishing are performed in two stages, with a roughing allowance of 0.2mm, and 3 teeth are turned each time; for dense teeth of the shaft diameter with good rigidity, they are turned into shape in one turn, with 5 teeth turned each time. This overcomes the problem of complex and inefficient single-tooth contour turning process in traditional dense tooth steam seal tooth machining, significantly shortening the machining time and improving production efficiency.

[0014] 2. The present invention discloses a cutting tool for turning steam turbine rotor steam seal teeth. It innovatively designs tooth structure with different tooth numbers and optimized cutting angles for the circumferential dense tooth turning tool and the shaft diameter dense tooth turning tool, which can not only ensure tooth profile accuracy, but also achieve a significant improvement in turning efficiency.

[0015] 3. The present invention discloses a cutting tool for turning steam turbine rotor steam seal teeth, which innovatively adopts a "spaced tooth structure" design. That is, the tooth pitch of the forming teeth of the turning tool is set as an integer multiple of the tooth pitch of the rotor steam seal teeth, the dense teeth of the circumferential band are distributed at twice the tooth pitch, and the dense teeth of the shaft diameter are distributed at once the tooth pitch. This solves the problem that the dense teeth are thin and the cutting teeth are difficult to manufacture. Attached Figure Description

[0016] Figure 1 A schematic diagram of the tool structure for high-efficiency turning of steam turbine rotor seal teeth; Figure 2 A schematic diagram of the coarse machining method for the surrounding belt with closely spaced teeth; Figure 3 A schematic diagram of the fine machining method for the mesh belt; Figure 4 A schematic diagram of a fine-tooth machining method for shaft diameter; Figure 5 A schematic diagram of the shaft diameter close-tooth chamfering method; In the diagram: 1-tool body, 2-insert screw, 3-roughing insert with fine teeth around the edge, 4-finishing insert with fine teeth around the edge, 5-finishing insert with fine teeth around the shaft diameter, 6-chamfering insert with fine teeth around the shaft diameter. Detailed Implementation

[0017] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0018] Example 1 A tool for turning steam turbine rotor steam seal teeth includes a cutting insert and a tool body. The cutting insert and the tool body are connected by a mechanical clamp. The cutting insert includes a roughing insert with dense teeth around the perimeter 3, a fine turning insert with dense teeth around the perimeter 4, a fine turning insert with dense teeth around the shaft diameter 5, and a chamfering insert with dense teeth around the shaft diameter 6. The coarse cutting insert with closely spaced teeth has 3 teeth. The cutting edge profile matches the tooth shape of the closely spaced teeth. Each tooth is inclined inward by 2° on one side. The cutting angle is 13° at the front angle, 7° at the back angle, and 3° at the two sides of each tooth. The precision cutting insert with closely spaced teeth has 3 teeth. The cutting edge profile matches the closely spaced teeth shape. Each tooth is inclined inward by 2° on one side. The cutting angle is 13° at the front angle, 7° at the back angle, and 3° at the two sides of each tooth. The shaft diameter fine-tooth precision turning insert has 5 teeth, and the cutting edge profile matches the shaft diameter fine-tooth tooth shape. Each tooth is inclined inward by 2° on one side. The shaft diameter fine-tooth chamfered blade has 5 teeth, and the cutting edge profile matches the shaft diameter fine-tooth tooth shape. Each tooth is inclined inward by 2° on one side, and each tooth has a 5° tangent at the end of the arc. The vertical distance from the starting point of this tangent to the top of the tooth is 0.5mm~0.6mm, and the length is extended to avoid the overlap mark at the joint of the two blades.

[0019] The tooth width of the coarse cutting insert with closely spaced teeth is 2.8mm, which is smaller than that of the fine cutting insert with closely spaced teeth. The roughing allowance is 0.2mm.

[0020] The tool body structure of the coarse turning tool with fine teeth, the fine turning tool with fine teeth, the axial diameter fine turning tool, and the axial diameter fine teeth chamfering tool is the same. The tool body clamping part is a standard square tool bar of 32mm×32mm. The width of the part of the square tool bar that holds the tool attachment is less than 32mm, and the top of the tool body has a 5° tilt angle.

[0021] The tooth pitch of the coarse cutting tool with dense teeth and the fine cutting tool with dense teeth is distributed at twice the tooth pitch of the rotor steam seal tooth.

[0022] The tooth pitch of the shaft diameter fine-tooth precision turning insert and the shaft diameter fine-tooth chamfering insert is distributed according to 1 times the tooth pitch of the rotor steam seal tooth.

[0023] Example 2 The present invention provides a turning method for machining the steam seal teeth of a turbine rotor. Based on the rigidity of different machining systems, the method corresponds to machining methods for dense teeth around the circumference and dense teeth around the shaft diameter. The specific steps are as follows: Rough turning with closely spaced teeth: Use a rough turning insert 3 with closely spaced teeth, install it onto the tool body 1 using insert screws 2, then clamp the entire insert onto the machine tool and perform tool setting using the quadrant point of the outermost tooth. Then perform machining according to cutting parameters of f=0.04mm / r~0.07mm / r and Vc=17m / min~26m / min; Figure 2As shown, three teeth are rough-machined each time, and all the steam seal teeth to be machined are rough-machined in sequence.

[0024] Fine turning with a banded tooth: Use a fine turning insert 4 with a banded tooth, install it on the tool body 1 using insert screws 2, then clamp the entire insert on the machine tool and perform tool setting using the quadrant point of the outermost tooth. Then perform machining according to cutting parameters of f=0.04mm / r~0.07mm / r and Vc=17m / min~26m / min; Figure 3 As shown, three teeth are precision machined each time, and all the steam seal teeth to be machined are precision machined in sequence.

[0025] Fine turning of shaft diameter with close-tooth profiles: Use fine turning insert 5, which is mounted on the tool body 1 using insert screw 2. Then, clamp the entire insert on the machine tool and perform tool setting using the quadrant point of the outermost tooth. Machining is then performed using cutting parameters of f=0.1mm / r~0.3mm / r and Vc=90m / min~110m / min. Figure 4 As shown, five teeth are precision machined each time, and all the steam seal teeth to be machined are precision machined in sequence.

[0026] Shaft diameter fine-tooth chamfering: Use shaft diameter fine-tooth chamfering insert 6, install it on the tool body 1 using insert screw 2, then clamp the entire insert on the machine tool and perform tool setting using the quadrant point of the outermost tooth, then perform machining according to cutting parameters of f=0.1mm / r~0.3mm / r, Vc=90m / min~110m / min; Figure 5 As shown, five teeth are chamfered at a time, and all the steam seal teeth to be processed are chamfered in sequence.

[0027] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A cutting tool for turning steam turbine rotor steam seal teeth, comprising a cutting tool and a tool body (1), characterized in that: The cutting tools include a coarse cutting tool with a dense toothed band (3), a fine cutting tool with a dense toothed band (4), a fine cutting tool with a dense toothed shaft diameter (5), and a chamfering tool with a dense toothed shaft diameter (6). The coarse cutting insert (3) with a dense toothed band has 3 teeth. The cutting edge profile matches the tooth shape of the dense toothed band. Each tooth is inclined inward by 2° on one side. The cutting angle is 13° at the front angle, 7° at the back angle, and 3° at the two sides of each tooth. The fine-tooth precision cutting insert (4) with a surrounding band has 3 teeth. The cutting edge profile matches the tooth shape of the surrounding band. Each tooth is inclined inward by 2° on one side. The cutting angle is 13° at the front angle, 7° at the back angle, and 3° at the two sides of each tooth. The shaft diameter fine-tooth precision turning insert (5) has 5 teeth, the cutting edge profile matches the shaft diameter fine-tooth tooth shape, and each tooth is inclined inward by 2° on one side. The shaft diameter closely spaced chamfered blade (6) has 5 teeth, the cutting edge profile matches the shaft diameter closely spaced tooth shape, each tooth is inclined inward by 2° on one side, and each tooth has a 5° tangent at the end of the arc. The vertical distance from the starting point of the tangent to the top of the blade tooth is 0.5mm~0.6mm.

2. The cutting tool for machining the steam seal teeth of a steam turbine rotor according to claim 1, characterized in that: The blade and the blade body (1) are connected by a mechanical clamp.

3. The cutting tool for machining the steam seal teeth of a steam turbine rotor according to claim 1, characterized in that: The tooth width of the coarse cutting insert (3) with a dense toothed band is smaller than that of the fine cutting insert (4) with a dense toothed band, and a roughing allowance of 0.2 mm is reserved.

4. The cutting tool for turning steam turbine rotor seal teeth according to claim 1, characterized in that: The tool body structures of the coarse turning tool (3) with a surrounding dense tooth, the fine turning tool (4) with a surrounding dense tooth, the fine turning tool (5) with a shaft diameter and the chamfering tool (6) with a shaft diameter are the same, and the tool body clamping part is a standard square tool bar of 32mm×32mm.

5. The cutting tool for machining the steam seal teeth of a steam turbine rotor according to claim 4, characterized in that: The width of the blade attachment part on the square blade shank is less than 32mm, and the top of the blade body has a 5° tilt angle.

6. The cutting tool for machining the steam seal teeth of a steam turbine rotor according to claim 1, characterized in that: The tooth pitch of the blade is set as an integer multiple of the tooth pitch of the rotor steam seal tooth.

7. The cutting tool for machining the steam seal teeth of a steam turbine rotor according to claim 6, characterized in that: The tooth pitch of the coarse cutting tool (3) with dense teeth and the fine cutting tool (4) with dense teeth is set to twice the tooth pitch of the rotor steam seal tooth.

8. The cutting tool for turning steam turbine rotor seal teeth according to claim 6, characterized in that: The tooth pitch of the shaft diameter fine-tooth precision turning insert (5) and the shaft diameter fine-tooth chamfering insert (6) is set at 1 times the tooth pitch of the rotor steam seal tooth.

9. A turning method for a tool used for turning the steam seal teeth of a steam turbine rotor as described in any one of claims 1-8, characterized in that, include: Rough turning with close-toothed band: Use a rough turning insert (3) with close-toothed band, install it on the cutter body (1) with insert screw (2), then clamp it on the machine tool and use the quadrant point of the outermost cutter tooth for tool setting, then drive the tool to feed according to the predetermined cutting parameters, rough turn three teeth each time, and complete the rough turning of all the steam seal teeth to be processed in sequence. Close-tooth precision turning with a band: Use a close-tooth precision turning insert (4) and install it on the tool body (1) with insert screws (2). Then clamp the entire insert on the machine tool and use the quadrant point of the outermost tooth for tool setting. Then drive the tool to feed according to the predetermined cutting parameters. Perform precision turning on three teeth at a time, and complete the precision turning of all the steam seal teeth to be processed in sequence. Shaft diameter fine turning: Use shaft diameter fine turning insert (5), install it on the tool body (1) with insert screw (2), then clamp it on the machine tool and use the quadrant point of the outermost tooth for tool setting, then drive the tool to feed according to the predetermined cutting parameters, rough turn five teeth each time, and complete all the steam seal teeth to be machined in sequence. Shaft diameter close-tooth chamfering: Use shaft diameter close-tooth chamfering insert (6), install it on the cutter body (1) with insert screw (2), then clamp it on the machine tool and use the quadrant point of the outermost cutter tooth for tool setting, then drive the tool to feed according to the predetermined cutting parameters, chamfer five teeth at a time, and complete all the steam seal teeth to be processed in sequence.

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