Low-pressure turbine rotor locking block hole processing method and processing tooling

Abstract

The application discloses a low-pressure turbine rotor locking block hole machining method and a machining tool. The machining tool comprises a supporting frame, a pressing screw and a pressing block. The supporting frame comprises a positioning circular-arc groove which is attached to the flange outer circle surface and the lower end surface of the center hole of the low-pressure turbine rotor, a supporting surface which is attached to the disc surface of the low-pressure turbine rotor, and a threaded hole which is parallel to the low-pressure turbine rotor. The pressing screw is installed in the threaded hole of the supporting frame, and the end of the pressing screw points to the locking block. The end of the pressing screw is T-shaped. The pressing block comprises a T-shaped groove which is parallel to the axial direction of the low-pressure turbine rotor and is inserted into the T-shaped end of the pressing screw. The pressing block further comprises a pressing surface which is attached to the surface of the locking block. The machining tool is used for drilling the locking block hole, and the locking block does not need to be manually fixed, so that the accidental deviation of the locking block during the drilling process is prevented, and the machining efficiency and reliability are improved.

Description

Technical Field

[0001] This invention belongs to the field of engine assembly technology, specifically relating to a tooling and method for fixing a low-pressure turbine rotor locking block and machining the locking block hole. Background Technology

[0002] like Figure 3 As shown, the low-pressure turbine rotor is designed with locking blocks to prevent the blades assembled in the tenon groove of the low-pressure turbine rotor from falling out of the tenon groove or moving around in the tenon groove. The locking blocks are first assembled with the tenon teeth of the low-pressure turbine rotor through a tenon and mortise structure (the assembly position is located at the boss of two adjacent tenons), and then fixed to the low-pressure turbine rotor by pins. Therefore, it is necessary to drill corresponding locking block holes on the low-pressure turbine rotor according to the mounting hole positions on the locking blocks for installing pins.

[0003] Currently, drilling locking block holes on low-pressure turbine rotors involves using a self-made tooling to fix the locking blocks, followed by drilling with a bench drill. However, the existing self-made tooling requires manual assistance from operators, which can easily cause the locking blocks to loosen during fixing. Furthermore, the installation process of the self-made tooling is cumbersome and can easily cause scratches to the low-pressure turbine disk assembly, while also increasing the risk of drilling locking block holes.

[0004] For the reasons mentioned above, there is an urgent need to develop a fixed locking block drilling tool to achieve high-quality and high-efficiency machining of locking block holes in low-pressure turbine rotors. Summary of the Invention

[0005] The present invention aims to provide a method and tooling for machining lock block holes of low-pressure turbine rotors, which can reduce the labor intensity of operators when machining lock block holes, achieve high safety and high efficiency machining, and improve the drilling quality of lock block holes.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A tooling for machining the lock block hole of a low-pressure turbine rotor includes:

[0008] The support frame includes a positioning arc groove that fits against the outer circular surface and lower end face of the flange edge of the center hole of the low-pressure turbine rotor, a support surface that fits against the disc surface of the low-pressure turbine rotor, and a threaded hole parallel to the radial direction of the low-pressure turbine rotor.

[0009] A clamping screw is installed in a threaded hole in the support frame, with the end of the clamping screw pointing towards the locking block, and the end of the clamping screw is T-shaped.

[0010] The pressure block includes a T-shaped groove parallel to the axial direction of the low-pressure turbine rotor and is inserted into the T-shaped end of the clamping screw through the T-shaped groove. The pressure block also includes a clamping surface that fits against the surface of the locking block.

[0011] As one embodiment, the support frame has a broken-line cross-section along the radial direction of the low-pressure turbine rotor and includes:

[0012] The first broken line segment with a threaded hole is parallel to the axial direction of the low-pressure turbine rotor;

[0013] The second broken line segment that is in contact with the disk surface of the low-pressure turbine rotor and parallel to the radial direction of the low-pressure turbine rotor;

[0014] The fourth broken line segment that fits against the outer circular surface and lower end face of the flange edge of the center hole of the low-pressure turbine rotor;

[0015] The third segment is used to connect the second and fourth segment.

[0016] As one option, the third zigzag segment has weight-reducing holes.

[0017] A method for machining the lock block hole of a low-pressure turbine rotor, using the aforementioned machining fixture, includes the following steps:

[0018] Step 1: Place the support frame on the low-pressure turbine rotor, ensuring that the support surface is in contact with the disk surface of the low-pressure turbine rotor, and ensuring that the positioning arc groove is in contact with the outer circular surface and lower end surface of the flange edge of the center hole of the low-pressure turbine rotor.

[0019] Step 2: Screw the clamping screw into the threaded hole of the support frame until the T-shaped end of the clamping screw moves near the locking block;

[0020] Step 3: Insert the pressure block into the T-shaped end of the clamping screw through the T-slot and fit it against the surface of the locking block along the axial direction of the low-pressure turbine rotor;

[0021] Step 4: Rotate the clamping screw to push the pressure block to move radially along the low-pressure turbine rotor and fit against the surface of the locking block;

[0022] Step 5: Using the through holes on the lock blocks, drill lock block holes one by one on the lock blocks at the tenon teeth of the low-pressure turbine rotor.

[0023] Furthermore, in step four, when the pressure block moves radially along the low-pressure turbine rotor and fits against the surface of the locking block, check and confirm that the assembly position of the locking block and the tenon has reached the stop point; in step five, when drilling the locking block hole, the drill bit must not contact the surface of the low-pressure turbine rotor.

[0024] Compared with the prior art, the present invention provides a processing method that enables the operator to directly drill lock block holes without manually fixing the lock block. This method can effectively improve the reliability of drilling lock block holes, so that only tooling is needed to fix the lock block during the drilling process, without considering the risk of lock block displacement during processing, which greatly improves the processing quality and eliminates the scrap problem caused by accidental displacement of the lock block.

[0025] Compared with the prior art, the present invention has the following characteristics:

[0026] (1) The operator does not need to manually fix the lock block. After installation using the machining tool, the lock block hole can be drilled directly to prevent the lock block from shifting during the drilling process.

[0027] (2) This invention can be widely applied to the machining of locking block holes in other types of low-pressure turbine rotors, improving the reliability and efficiency of machining and ensuring a 100% pass rate.

[0028] (3) During the drilling of the locking block hole, the radial and axial positioning and limiting are achieved by utilizing the structural features of the low-pressure turbine rotor itself (outer circle of the flange edge, end face and disc surface). There is no interference structure during drilling and assembly of the locking block. (4) The operation is simple. It can be completed by simply tightening the clamping screw along the radial direction of the low-pressure turbine rotor. There are no additional connecting parts (such as screws, bolts and pins) when assembling and disassembling the machining tooling. It will not damage the surface structure of the low-pressure turbine rotor. There are no complicated tooling installation and disassembly operations. The tooling is highly efficient. Attached Figure Description

[0029] Figure 1 This is a cross-sectional view of the tooling used for machining the lock block hole of the low-pressure turbine rotor;

[0030] Figure 2 It includes Figure 1 Top view of the tooling for machining the lock block hole of the low-pressure turbine rotor at section AA;

[0031] Figure 3 This is a schematic diagram of drilling and locking block holes in a low-pressure turbine rotor;

[0032] Figure 4 yes Figure 3 View from direction B;

[0033] In the diagram: 1. Support frame, 2. Pressure block, 3. Clamping screw. Detailed Implementation

[0034] The present invention will be further described below with reference to specific embodiments, but it should not be construed as limiting the scope of the subject matter of the present invention to the following embodiments. All modifications, substitutions and alterations made based on ordinary technical knowledge and common practices in the art without departing from the above-described technical concept of the present invention are included within the scope of the present invention.

[0035] like Figure 3As shown, a locking block structure is located at the protrusion position of two adjacent tenons on the tenon end face of the low-pressure turbine rotor. To secure the locking block to the low-pressure turbine rotor, corresponding locking block holes need to be drilled on the rotor below the turbine blades. The purpose of drilling these locking block holes is to install retaining rings under each tenon after the turbine blades are installed on the low-pressure turbine rotor. The two ends of the retaining ring fit precisely into the two ends of the locking block. Two through holes are drilled on the tenons of the low-pressure turbine rotor through the mounting holes of the locking block itself to serve as locking block holes. Finally, pins are pressed into the locking block holes to fix the locking block to the low-pressure turbine rotor, thus securing the retaining rings and preventing them from falling off. This, in turn, prevents the turbine blades installed in the tenon from axially shifting or even falling off. (Reference) Figures 1-3 The locking block and the tenon teeth of the low-pressure turbine rotor adopt a mortise and tenon structure (see...). Figure 1 The locking block has a groove structure that engages with the boss of the tenon. When the locking block is assembled at the tenon, the locking block itself will not easily produce axial and circumferential offset relative to the low-pressure turbine rotor. However, due to the lack of radial restraint, during the drilling of the locking block hole, the locking block will not only produce radial offset and disengage from the tenon boss, but will also produce axial and circumferential offset under the vibration of the drill bit, resulting in changes in the shape and positional accuracy of the locking block hole.

[0036] In this invention, the design concept of the machining fixture for the locking block hole of the low-pressure turbine rotor is as follows: based on the actual machining situation of the locking block hole of the low-pressure turbine rotor on site, the positioning and clamping method of the machining fixture are determined, it is judged whether the machining fixture will cause interference, and the design is carried out according to the assembly relationship between the locking block and the tenon teeth of the low-pressure turbine rotor and the requirements raised during the on-site machining process.

[0037] Determine the fixing method for the machining tooling of the low-pressure turbine rotor lock block hole: First, avoid the existing manual-assisted fixing method, that is, the operator should not be able to manually participate in fixing the lock block during the drilling of the lock block hole. Second, ensure that the fixing method is simple and efficient, and avoid complicated tooling operations and interference problems.

[0038] In light of the above requirements, the present invention designs the following solution:

[0039] The low-pressure turbine rotor locking block hole machining fixture consists of a support frame 1, a pressure block 2, and a clamping screw 3 (see...). Figure 1 The support frame 1 is positioned by the end face of the center hole on the low-pressure turbine rotor (see...). Figure 1 and Figure 2At the right end, there is a circular stepped through-hole at the central axis of the low-pressure turbine rotor. The portion of this circular stepped through-hole protruding from the low-pressure turbine rotor disk has a flange edge. The outer circular surface and lower end face of this flange edge serve as the positioning surface of the support frame 1, and the low-pressure turbine disk surface serves as the support surface. The support frame 1 is formed by bending a single sheet of material three times to create a structure that is radially mounted along the low-pressure turbine rotor. The first bend has a threaded hole for installing the clamping screw 3. The second bend fits against the disk surface of the low-pressure turbine rotor. The third bend has a weight-reducing hole to lower the weight of the entire machining fixture and extends the machining fixture to the flange edge of the central through-hole of the low-pressure turbine rotor. The fourth bend fits against the outer circle and lower end face of the flange edge of the central through-hole of the low-pressure turbine rotor. The support frame 1 achieves radial limitation of the locking block through the flange edge of the central through-hole of the low-pressure turbine rotor. Furthermore, the support frame 1 achieves radial and axial limitation through the flange edge of the central through-hole of the low-pressure turbine rotor and the disk surface of the low-pressure turbine rotor, respectively, ensuring reliable installation. The end of the pressure block 2 that contacts the locking block has a conformal design, processed according to the surface shape of the locking block to ensure a tight fit when they are in contact. The pressure block 2 is installed at the front end of the clamping screw 3, which can move radially through the threaded hole of the support frame 1. The pressure block 2 is assembled with the T-shaped head of the clamping screw 3 through its own T-slot, ensuring the axial freedom of both in the low-pressure turbine rotor. The tenon teeth of the locking block and the low-pressure turbine rotor are mortise and tenon structures. When there is no radial force from the pressure block 2, the locking block will shift due to the action of the drill bit. In this invention, the clamping screw 3 only needs to apply a very small force to ensure that the locking block will not undergo axial, circumferential, or radial displacement during the drilling of the locking block hole.

[0040] like Figure 3 As shown, before drilling the locking block holes, first press the locking block along the W direction to the stop point (the stop point refers to the position where the groove on the locking block can fully fit with the tenon boss of the low-pressure turbine rotor, i.e., the position point when the mortise and tenon structure is fully assembled). Drill holes sequentially according to the original through holes on the locking block (i.e., the two pin holes on the locking block for the pins), ensuring... Figure 4 As shown in the dimensions, the drill bit must not cut into the end face T1 of the low-pressure turbine rotor during drilling (end face T1 refers to the surface of the tenon groove on the low-pressure turbine rotor; if it cuts into the surface, cracks will appear there, increasing stress and significantly reducing strength, which could lead to engine breakage during operation). When installing the locking block, use a machining tool to hold the clamping screw 3 along... Figure 3 Tighten the locking block in the W direction to the stop point, and the locking block will be fixed in a fixed state without interfering with the downward movement of the drill bit. Using this fixture to fix the locking block avoids the risk of the locking block shifting during processing, and the operation is simple, avoiding a complicated disassembly and assembly process. It will not interfere with the low-pressure turbine rotor, and relies on the structural characteristics of the low-pressure turbine rotor itself to achieve precise positioning and limiting, which greatly improves the reliability and drilling efficiency of drilling the locking block hole.

[0041] Contents not described in detail in this specification are prior art known to those skilled in the art. Although illustrative specific embodiments of the invention have been described above to facilitate understanding by those skilled in the art, it should be understood that the invention is not limited to the scope of the specific embodiments. Various modifications are readily apparent to those skilled in the art as long as they fall within the spirit and scope of the invention as defined and determined by the appended claims, and all inventions utilizing the concept of this invention are protected.

Claims

1. A tooling for machining the lock block hole of a low-pressure turbine rotor, characterized in that, include: The support frame (1) includes a positioning arc groove that fits with the outer circular surface and lower end surface of the flange edge of the center hole of the low-pressure turbine rotor, a support surface that fits with the disk surface of the low-pressure turbine rotor, and a threaded hole parallel to the radial direction of the low-pressure turbine rotor. A clamping screw (3) is installed in a threaded hole in the support frame (1) and the end of the clamping screw (3) points to the locking block. The end of the clamping screw (3) is T-shaped. The pressure block (2) includes a T-shaped groove parallel to the axial direction of the low-pressure turbine rotor and is inserted into the T-shaped end of the clamping screw (3) through the T-shaped groove. The pressure block (2) also includes a clamping surface that fits against the surface of the locking block.

2. The tooling for machining the lock block hole of a low-pressure turbine rotor according to claim 1, characterized in that: The support frame (1) has a broken-line cross-section along the radial direction of the low-pressure turbine rotor and includes: The first broken line segment with a threaded hole is parallel to the axial direction of the low-pressure turbine rotor; The second broken line segment that is in contact with the disk surface of the low-pressure turbine rotor and parallel to the radial direction of the low-pressure turbine rotor; The fourth broken line segment that fits against the outer circular surface and lower end face of the flange edge of the center hole of the low-pressure turbine rotor; The third segment is used to connect the second and fourth segment.

3. The tooling for machining the lock block hole of a low-pressure turbine rotor according to claim 2, characterized in that: The third broken line segment has a weight-reducing hole.

4. A method for machining the locking block hole of a low-pressure turbine rotor, characterized in that, The machining fixture described in claim 1 is used, and the process includes the following steps: Step 1: Place the support frame (1) on the low-pressure turbine rotor, ensuring that the support surface is in contact with the disk surface of the low-pressure turbine rotor, and ensuring that the positioning arc groove is in contact with the outer circular surface and lower end surface of the flange edge of the center hole of the low-pressure turbine rotor. Step 2: Screw the clamping screw (3) into the threaded hole of the support frame (1) until the T-shaped end of the clamping screw (3) moves near the locking block; Step 3: Insert the pressure block (2) into the T-shaped end of the clamping screw (3) through the T-slot and fit it against the surface of the locking block along the axial direction of the low-pressure turbine rotor; Step 4: Rotate the clamping screw (3) to push the pressure block (2) to move radially along the low-pressure turbine rotor and fit against the surface of the locking block; Step 5: Using the through holes on the lock blocks, drill lock block holes one by one on the lock blocks at the tenon teeth of the low-pressure turbine rotor.

5. The method for machining the lock block hole of a low-pressure turbine rotor according to claim 4, characterized in that: In step four, when the pressure block (2) moves radially along the low-pressure turbine rotor and fits against the surface of the locking block, check and confirm that the assembly position of the locking block and the tenon has reached the stop point. The stop point refers to the position where the groove on the locking block can fully fit against the tenon boss of the low-pressure turbine rotor, that is, the position point when the tenon structure is fully assembled. In step five, when drilling the lock block hole, the drill bit must not come into contact with the surface of the low-pressure turbine rotor.

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