A fixture for machining the radial face of a steam turbine blade on a four-axis machine

Abstract

The present application relates to the technical field of machining, in particular to a clamp for machining the radial surface of a steam turbine blade by a four-axis machine tool; the driving disc is fixedly installed on the upper surface of a displacement base, and the displacement base is used for driving the driving disc to adjust the lifting; the driving disc is provided with a core expansion clamp used for internally expanding and positioning the shaft hole of the steam turbine blade. The radial driving assembly comprises a ring sleeve base, a worm drive, a plurality of rotating guide rods, a push head and a linkage rod. The ring sleeve clamp group is composed of a clamping ring, a split clamping petal and an abutment, the split clamping petal can be self-adapted to the outer periphery of the blade under the deformation of the clamping ring, and the surface of the abutment is provided with a flexible rubber pad to prevent surface damage. The bidirectional clamping structure combining internal expansion and external wrapping is used to realize high-precision positioning and stable clamping of the steam turbine blade, and the present application has the advantages of automatic adjustment, flexible wrapping and high repeat accuracy, and significantly improves the stability and processing efficiency of the four-axis machine tool processing.

Description

Technical Field

[0001] This invention relates to the field of machining technology, specifically to a fixture for machining the radial surface of turbine blades on a four-axis machine tool. Background Technology

[0002] As the core power component of a steam turbine, turbine blades have complex surface shapes and require extremely high geometric precision, typically necessitating multi-angle composite machining on four-axis or multi-axis machine tools. Existing blade machining fixtures mainly employ mechanical locking, peripheral chuck clamping, or end-face clamping structures, using external force to fix the blade for machining positioning. However, in actual machining, due to the asymmetrical shape, complex curved surface, and uneven stress distribution of steam turbine blades, traditional fixtures still exhibit significant shortcomings in clamping stability, positioning accuracy, and self-adaptive capability.

[0003] In existing technologies, typical structures include:

[0004] End-face clamping fixtures typically use push rods or pressure plates to apply pressure to the root or end face of the blade to fix the workpiece. While this method is simple to operate, it is prone to runout at high-speed rotation or with large cutting forces, leading to increased blade vibration, decreased clamping accuracy, and difficulty in ensuring the coaxiality and surface finish of the machined surface.

[0005] The outer ring chuck type fixture uses multiple equidistant jaws to radially clamp the outer edge of the blade, achieving fixation through mechanical adjustment. This method provides strong clamping force, but the limited contact points of the jaws can easily lead to localized stress concentrations, causing indentations or micro-deformations on the blade surface, which is detrimental to maintaining the accuracy of subsequent finishing processes.

[0006] Tapered sleeve positioning fixtures use tapered positioning cores or expansion sleeves to achieve internal hole clamping and positioning, which can ensure axial accuracy. However, they can only achieve unidirectional constraint and cannot resist radial displacement caused by the cutting force of the outer edge of the blade. At the same time, they lack external covering constraint structures, resulting in insufficient clamping stability.

[0007] For turbine blades with complex shapes and multi-directional cutting requirements, existing fixture technologies generally suffer from the following main problems:

[0008] (1) The clamping direction is singular and the constraint is not comprehensive. Traditional fixtures are mostly unidirectional internal expansion or external pressure structures, which cannot simultaneously form bidirectional locking of the inner hole and outer periphery of the blade, resulting in blade eccentricity and micro-vibration during processing.

[0009] (2) Poor flexibility and self-adaptation. The shape of the blades varies greatly, and there are slight deviations in the outer edge curvature of blades from different batches or models. Conventional clamps cannot automatically compensate for the surface error, which can easily cause uneven stress on the blade surface, local stress concentration, or even damage to the blade surface during clamping.

[0010] (3) The clamping and adjustment are complicated and the repeatability is low. Most existing structures rely on manual adjustment or manual locking, which makes it difficult to quickly reset the machining angle and automatically control the clamping. This results in low clamping efficiency, large repeatability error, and is not conducive to the stability of multi-angle continuous machining.

[0011] Therefore, existing turbine blade clamping devices still have significant technical bottlenecks in terms of multi-directional constraint, flexible fitting, and automated control, failing to meet the demands of modern four-axis machine tools for high stability, high precision, and high efficiency machining. In view of this, this paper studies and improves upon existing solutions to provide a fixture for machining the radial surface of turbine blades on a four-axis machine tool. Summary of the Invention

[0012] This invention aims to solve the problems of low clamping accuracy, large vibration offset, and easy damage to turbine blades in the multi-angle machining of existing turbine blades. To this end, this invention provides a clamping structure that combines compact structure, bidirectional clamping, adaptive deformation, and controllable drive.

[0013] The fixture consists of a displacement base, a drive disk, a radial drive assembly, and a ring clamping group. It achieves stable fixation of turbine blades through a bidirectional constraint clamping structure, and completes automatic clamping and angle adjustment in conjunction with an electric drive and mechanical linkage structure, making it suitable for multi-angle high-precision machining scenarios on four-axis machine tools.

[0014] In this invention, a core expansion clamp is used to internally expand and position the blade shaft hole, forming an axial reference. A ring clamping assembly then provides omnidirectional flexible wrapping and clamping of the blade's outer periphery, forming radial support. A displacement base and a multi-motor drive system enable operations such as lifting, adjusting, automatic clamping, and synchronous release. A worm gear actuator and linkage structure allow multiple rotating guide rods to deflect synchronously, achieving uniform clamping force and stable linkage transmission. Through this comprehensive design, the blade can simultaneously obtain multi-dimensional constraints in the axial, radial, and circumferential directions during processing, thereby ensuring stable blade attitude, high coaxial accuracy, and uniform surface stress distribution.

[0015] The clamp of the present invention includes a displacement base, a drive disk, a radial drive assembly, and a ring clamping group. The drive disk is fixedly installed on the displacement base, which can move up and down to adjust the clamping position of the turbine blade. The drive disk is provided with a core expansion clamp for internal expansion positioning of the blade shaft hole; a first drive motor and a second drive motor are provided on both sides of the drive disk, which are respectively used to drive the radial drive assembly to rotate and control the core expansion clamp to tighten. The core expansion clamp includes a guide cone cylinder, a lead screw, a cone expansion block, and an expansion sleeve. The guide cone cylinder is fixedly installed at the surface axis of the drive disk. The top end of the lead screw is fixedly connected to the cone expansion block and is sleeved on the inner side of the guide cone cylinder and the expansion sleeve. The expansion sleeve is slidably sleeved on the outer surface of the guide cone cylinder and the cone expansion block to realize radial expansion and contraction clamping action under the drive of the lead screw.

[0016] The radial drive assembly includes a ring holder, a worm gear actuator, a rotating guide rod, a pusher head, and a linkage rod. The worm gear actuator drives the rotating guide rod to deflect, and the rotating guide rod deflects synchronously through a crank arm and a linkage rod, thereby driving the pusher head to move radially. The outer end of the pusher head is detachably connected to the ring holder assembly, and is used to drive the ring holder assembly to expand or contract radially.

[0017] Specific effects: By forming a two-way clamping system through two sets of internal and external structures, the turbine blades are positioned by inner hole expansion and the outer periphery is flexibly wrapped and clamped, ensuring the coaxiality and clamping stability of the blades during multi-axis machining and preventing vibration and displacement.

[0018] In a preferred example, the displacement base includes a fixed base, a lifting head, a main boom, and a secondary boom. The main boom and the secondary boom are arranged parallel to each other and rotatably connected to the fixed base. The fixed base is equipped with a servo motor for driving the main boom to deflect, thereby driving the lifting head and drive plate to adjust their height.

[0019] Specific effects: This structure enables the overall height and angle of the fixture to be adjustable, which can quickly adapt to the processing requirements of turbine blades of different specifications and angles, and improve the clamping flexibility and processing space adaptability.

[0020] In a preferred embodiment, the bottom of the ring seat is provided with a toothed ring that meshes with the output end of the first drive motor, used to drive the radial drive assembly to rotate and adjust the angle; the second drive motor is linked to the guide cone cylinder through a lead screw, driving the lead screw to move axially to move the conical expansion block forward, forcing the expansion sleeve to expand radially, thereby achieving reliable expansion and positioning of the blade's inner bore. The conical expansion block and the expansion sleeve adopt a conical sliding contact design, and the expansion sleeve is a deformable metal sleeve structure that can automatically retract when loosened, facilitating blade loading and unloading.

[0021] Specific effects: The motor-driven lead screw enables automated internal expansion positioning and clamping actions, improving operational convenience and repeatability accuracy, reducing manual intervention, and enhancing the level of automation.

[0022] In a preferred example, several guide rods are evenly distributed along the circumference of the ring seat. The surface of the guide rods is provided with helical grooves, and the ring seat is provided with helical guide ridges to convert rotation into axial sliding. The front end of the guide rods is connected to a pusher, which slides against the ring seat through a slide bar to ensure the stability of radial movement.

[0023] Adjacent rotary guide rods are movably connected by crank arms and linkage rods to form a mechanical linkage system, so that the worm gear actuator only needs to drive one rotary guide rod to drive all rotary guide rods to deflect synchronously.

[0024] Specific effects: This design enables synchronous driving of each clamping unit of the ring clamping assembly, resulting in uniform clamping force distribution, avoiding single-point overload or uneven clamping, and improving overall clamping stability and service life.

[0025] In a preferred example, the ring clamp assembly includes a clamping ring, a split clamping flap, an abutment, and a rubber pad.

[0026] The surface of the clamping ring is divided into multiple sets of deformation gaps along the inner and outer circumferences. Each deformation gap is staggered along the circumferential direction and corresponds to the position of the pusher head to ensure uniform force during clamping.

[0027] Both the parting clip and the abutment are semi-circular cylindrical structures. The parting clip is installed on the clamping ring through a rotating shaft. Its surface is provided with two or more abutments, and flexible rubber pads are fixedly installed on the surface of the abutments.

[0028] During the clamping process, the split-type clamping segments can deform and deflect synchronously under the drive of the pusher, and the abutment can adaptively fit the outer contour of the turbine blade to achieve flexible wrapping and clamping.

[0029] Specific effects: The linkage structure of flexible rubber pads and split-type clamping flaps can effectively reduce the risk of local stress concentration and surface scratches, while improving the fit of the clamping surface and the stability of blade positioning.

[0030] The beneficial effects achieved by this invention are as follows:

[0031] 1. In this invention, the blade shaft hole is internally expanded and positioned by the core expansion fixture on the drive disk, and the ring clamping group is driven by the radial drive component to achieve omnidirectional wrapping and clamping of the outer periphery, forming a bidirectional constraint structure that effectively prevents the blade from vibrating and shifting during the processing, and significantly improves the stability and coaxial accuracy of radial surface processing.

[0032] 2. In this invention, the ring clamping assembly adopts a linkage structure of clamping ring, split clamping petals and abutment. Each clamping petal can synchronously and adaptively deflect under the change of the clamping ring, which can adaptively fit the outer contour of turbine blades of different specifications, realize flexible wrapping and clamping, and reduce local stress concentration and surface damage.

[0033] 3. In this invention, the overall lifting and adjustment is achieved through the displacement base. The first drive motor and the second drive motor control the radial rotation and axial expansion respectively. The worm gear driver links multiple rotary guide rods to complete synchronous driving, so that the fixture has the characteristics of fast positioning, automatic adjustment and high repeatability, which is suitable for high-precision machining of complex curved surfaces on four-axis machine tools. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the overall structure of one embodiment of the present invention;

[0035] Figure 2 This is a schematic diagram of a displacement base structure according to an embodiment of the present invention;

[0036] Figure 3 This is a schematic diagram of the drive disk and radial drive assembly structure according to an embodiment of the present invention;

[0037] Figure 4 This is a partial cross-sectional structural diagram of a core expansion clamp according to an embodiment of the present invention;

[0038] Figure 5 This is a schematic diagram of the radial drive component structure according to an embodiment of the present invention;

[0039] Figure 6 This is a schematic diagram of the surface structure of the ring seat according to an embodiment of the present invention;

[0040] Figure 7 This is a schematic diagram of the worm gear actuator, guide rod, and pusher mounting structure according to an embodiment of the present invention;

[0041] Figure 8 This is a schematic diagram of the rotating guide rod and pusher structure according to an embodiment of the present invention;

[0042] Figure 9 This is an exploded view of the ring clamp assembly according to an embodiment of the present invention.

[0043] Figure label:

[0044] 100. Displacement base; 110. Fixed base; 120. Lifting head; 130. Main boom; 140. Auxiliary boom;

[0045] 200. Drive disc; 210. First drive motor; 220. Second drive motor; 230. Core expansion clamp; 231. Guide cone cylinder; 232. Lead screw; 233. Conical expansion block; 234. Expansion sleeve;

[0046] 300, Radial drive assembly; 310, Ring sleeve seat; 320, Worm gear actuator; 330, Rotary guide rod; 340, Push head; 350, Linkage rod; 311, Screw sleeve seat; 331, Helical groove; 332, Crank arm; 341, Slide rod;

[0047] 400. Ring clamping assembly; 410. Clamping ring; 411. Deformation gap; 420. Parting clamp; 430. Abutment; 431. Rubber pad. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0049] It should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the invention.

[0050] The following describes, with reference to the accompanying drawings, some embodiments of the present invention, a fixture for machining the radial surface of a steam turbine blade on a four-axis machine tool.

[0051] Combination Figures 1-9 As shown, the present invention provides a fixture for machining the radial surface of turbine blades on a four-axis machine tool, comprising a displacement base 100, a drive disk 200, a radial drive assembly 300, and a ring clamping group 400. This fixture can achieve precise positioning and stable clamping of turbine blades during the machining process on a four-axis machine tool through a composite clamping method combining inner hole expansion and outer edge covering.

[0052] The drive disk 200 is fixedly mounted on the upper surface of the displacement base 100 to support the entire clamping mechanism. The displacement base 100 is configured as a lifting structure, which can drive the drive disk 200 to move up and down, thereby adjusting the clamping height of the turbine blades.

[0053] The radial drive assembly 300 is rotatably mounted on the upper surface of the drive disk 200 for adjusting the blade's attitude. A core expansion clamp 230 is located in the center of the drive disk 200 for internal expansion positioning of the turbine blade's shaft hole. A first drive motor 210 and a second drive motor 220 are fixedly mounted on both sides of the drive disk 200, respectively. The first drive motor 210 drives the radial drive assembly 300 to rotate and adjust its angle on the drive disk 200; the second drive motor 220 drives the core expansion clamp 230 to perform the internal expansion action.

[0054] The radial drive assembly 300 includes a ring seat 310, a worm gear drive 320, several guide rods 330, a pusher 340, and a linkage rod 350. The surface of the ring seat 310 is provided with several threaded sleeve seats 311. The guide rods 330 are threaded onto the threaded sleeve seats 311 and arranged radially through the ring seat 310. One end of the pusher 340 is provided with a slide rod 341, which slides radially through the ring seat 310 and abuts against the end of the guide rod 330. A crank arm 332 is fixed to the surface of the guide rod 330. Adjacent guide rods are synchronously deflected through the crank arm 332 and the linkage rod 350. The worm gear drive 320 drives one of the guide rods to actively deflect, thereby driving the entire assembly to move.

[0055] The ring clamping assembly 400 is disposed on the outer periphery of the ring holder 310, and a plurality of clamping rings 410 are formed on its surface. Parting clips 420 are rotatably mounted on the inner side of the clamping rings 410, and lugs 430 are rotatably mounted on the surface of the parting clips. The outer peripheral surface of the clamping rings 410 is detachably connected to the end of the pusher head 340, so that the ring clamping assembly is deformed as a whole when the pusher head moves radially.

[0056] This structure enables the turbine blades to be precisely expanded and positioned at the inner hole by the core expansion clamp 230, while at the outer edge they are flexibly wrapped and clamped by the ring clamp group 400, forming a stable clamping state in both the inner and outer directions.

[0057] In this embodiment, the displacement base 100 includes a fixed base 110, a lifting head 120, and a main arm 130 and a secondary arm 140 rotatably mounted on one side of the lifting head 120. The main arm 130 and the secondary arm 140 are arranged parallel to each other, with one end connected to the fixed base 110 via a pin and the other end supporting the lifting head 120. A servo motor or electric drive device is mounted on the fixed base 110 to drive the main arm 130 to deflect. The coordinated deflection of the main arm 130 and the secondary arm 140 realizes the lifting and lowering action of the lifting head 120 and the drive disk 200, thereby facilitating multi-angle machining and positioning of the blades on a four-axis machine tool.

[0058] In this embodiment, the bottom surface of the ring seat 310 is provided with a toothed ring that meshes with the output end of the first drive motor 210, thereby realizing the rotational drive of the ring seat 310. The output end of the second drive motor 220 is connected to the bottom end of the lead screw 232 through a coupling. The lead screw 232 is threaded onto the inner side of the guide cone cylinder 231, thereby converting the rotational motion into axial displacement for controlling the working stroke of the core expansion clamp 230.

[0059] In this embodiment, the core expansion clamp 230 includes a guide cone cylinder 231, a lead screw 232, a conical expansion block 233, and an expansion sleeve 234. The guide cone cylinder 231 is fixedly installed at the axial position of the drive disk 200. The top end of the lead screw 232 is fixedly connected to the conical expansion block 233, and the lead screw 232 is sleeved on the inner side of the guide cone cylinder 231 and the expansion sleeve 234. The expansion sleeve 234 is slidably sleeved on the outer surface of the guide cone cylinder 231 and the conical expansion block 233, and is used to realize radial expansion and contraction clamping under the drive of the lead screw 232. The outer surface of the guide cone cylinder 231 and the outer surface of the conical expansion block 233 are both provided with conical surface structures, which slide and cooperate with the conical surface of the inner wall of the expansion sleeve 234. When the lead screw 232 drives the conical expansion block 233 to move forward, the expansion sleeve 234 expands uniformly outward in the radial direction, thereby realizing the expansion and clamping of the inner hole of the turbine blade. The expansion sleeve 234 is a deformable metal sleeve structure with elastic recovery performance, which can automatically retract in the loosened state to facilitate blade removal.

[0060] In this embodiment, several threaded sleeve seats 311 and rotating guide rods 330 are evenly distributed along the circumference of the ring sleeve seat 310. The crank arm 332 is provided with a ball-head pin structure connected to the end of the linkage rod 350. The ball head connects to the linkage rod, ensuring that each rotating guide rod 330 maintains a flexible transmission relationship during deflection. Adjacent rotating guide rods 330 are movably connected to each other through the linkage rod 350, forming a mechanical linkage mechanism to ensure synchronous deflection of multiple rotating guide rods 330, thereby ensuring uniform deformation of the entire ring sleeve clamp assembly 400.

[0061] In this embodiment, the surface of the rotary guide rod 330 is provided with a helical groove 331, and the inner side of the threaded sleeve seat 311 is provided with a helical guide ridge that engages with the helical groove 331. This mating structure can guide the rotary guide rod 330 to generate axial sliding when it deflects. The surface of the push head 340 is provided with a slide rod 341, which is arranged parallel to the rotary guide rod 330. The slide rod 341 slides radially in the ring sleeve seat 310 and is used to push or retract the ring sleeve clamping assembly 400, thereby realizing the expansion or contraction of the clamping mechanism.

[0062] like Figure 9 As shown, the surface of the clamping ring 410 is divided into multiple sets of deformation gaps 411 along both the inner and outer circumferences. The deformation gaps 411 are staggered along the circumferential direction, so that the clamping force can be evenly distributed in the radial direction. The multiple deformation gaps 411 are distributed along the circumferential direction of the ring seat 310 and are located between adjacent push heads 340 to ensure that each push head driving area corresponds to an independent clamping unit, thereby achieving a uniform coverage and symmetrical clamping effect.

[0063] like Figure 9 As shown, both the parting clip 420 and the lug 430 are semi-circular cylindrical structures. Each parting clip 420 is mounted on the surface of the clamping ring 410 via a rotating shaft, allowing it to freely deflect during clamping to adapt to the complex outer curved surface of the turbine blade. Each parting clip 420 has two or more lugs 430 on its surface, and a rubber pad 431 is fixedly installed on the outer surface of the lug. The rubber pad 431 is made of wear-resistant flexible material to reduce clamping pressure and prevent scratches on the blade surface.

[0064] Working principle and usage process of this invention:

[0065] When turbine blades need to be machined radially, the blade to be machined is first placed on the outer surface of the core expansion clamp 230, so that the blade shaft hole is coaxially aligned with the expansion sleeve 234; then, the displacement base 100 drives the drive disk 200 to rise and fall to a suitable clamping height. At this time, the radial drive assembly 300 on the drive disk 200 is driven by the first drive motor 210 to achieve angular rotation, thereby adjusting the spatial orientation of the turbine blade so that its machining surface and the movement trajectory of the machine tool maintain the optimal machining angle.

[0066] During the positioning phase, the second drive motor 220 starts and drives the lead screw 232 to rotate. The lead screw 232 engages with the guide cone cylinder 231 via a thread, causing the guide cone cylinder 231 to undergo axial displacement, which pushes the cone expansion block 233 located at the front end forward axially. The cone expansion block 233 and the inner wall of the expansion sleeve 234 have a cone-surface contact relationship. As the cone expansion block 233 moves forward, the expansion sleeve 234 expands radially outward, generating a uniform internal expansion force that acts on the inner wall of the turbine blade shaft hole, achieving preliminary positioning and clamping of the blade in the axial and radial directions.

[0067] After initial positioning, the operator or control system can further activate the radial drive assembly 300. The worm gear drive 320 rotates under motor drive, generating angular displacement through the connected guide rod 330. The outer surface of the guide rod 330 has a helical groove 331, which meshes with the helical guide ridge on the inner side of the threaded sleeve seat 311, converting the angular displacement into radial axial displacement during rotation. Consequently, the push head 340 slides radially along the ring seat 310 under the guidance of the slide rod 341, pushing the ring clamp assembly 400 to expand or tighten.

[0068] When the pusher head 340 moves radially inward, the clamping ring 410 connected to its end undergoes radial contraction deformation, driving the parting clip 420 to move synchronously. When the parting clip 420 contacts the outer edge of the blade, it adaptively deflects. Each parting clip 420 and its surface lugs 430 adaptively deflect to adapt to the outer circumferential surface of the turbine blade. The rubber pads 431 on the surface of the lugs 430 can effectively buffer the clamping pressure and prevent damage to the machined surface, achieving flexible fit and stable coverage of the outer edge of the blade.

[0069] Throughout the clamping process, multiple rotary guide rods 330 form a mechanical synchronization network with the linkage rod 350 through the crank arm 332, so that the worm gear drive 320 only needs to drive one rotary guide rod 330 to drive all rotary guide rods 330 to move in tandem, ensuring that the clamping force is evenly distributed on the outer circumference of the blade and avoiding deformation caused by off-center loading.

[0070] At this point, the turbine blade is positioned internally by the core expansion clamp 230 and clamped externally by the ring clamping assembly 400, forming a stable two-way clamping state. Under the control of the four-axis machine tool, the clamp can perform actions such as attitude adjustment, automatic clamping, and synchronous release, ensuring that the turbine blade maintains high-precision positioning and high stability during multi-angle machining, thereby improving the form and position accuracy of radial surface machining and overall machining efficiency.

[0071] In the description of this specification, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0072] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A fixture for machining a radial face of a steam turbine blade on a four- axis machine tool, characterized by, It comprises a displacement base (100), a driving disc (200), a radial driving assembly (300) and a ring sleeve clamp group (400); The driving disc (200) is fixedly installed on the upper surface of the displacement base (100), and the displacement base (100) is used for driving the driving disc (200) to move up and down; the radial driving assembly (300) is rotatably installed on the upper surface of the driving disc (200); The radial driving assembly (300) comprises a ring sleeve base (310), a worm drive (320), a plurality of rotating guide rods (330), a push head (340) and a linkage rod (350), a plurality of screw sleeve bases (311) are fixedly installed on the surface of the ring sleeve base (310), the plurality of rotating guide rods (330) are threadedly sleeved on the inner surface of the screw sleeve base (311) and distributed along the radial direction through the ring sleeve base (310), one end of the push head (340) is provided with a sliding rod (341), the sliding rod (341) is slidably connected with the screw sleeve base (311) along the radial direction through the ring sleeve base (310), and one end of the push head (340) abuts against one end of the rotating guide rod (330); a plurality of clamping rings (410) are formed on the surface of the ring sleeve clamp group (400), and the outer peripheral surface of the clamping ring (410) is detachably connected with the outer end of the push head (340); The surface of the rotating guide rod (330) is fixedly installed with a crank arm (332), the adjacent rotating guide rods (330) are synchronously deflected through the crank arm (332) and the linkage rod (350), and one of the rotating guide rods (330) is driven to actively deflect by the worm drive (320); The surface of the rotating guide rod (330) is provided with a spiral groove (331), and the inner side of the screw sleeve base (311) is provided with a spiral guide edge engaged with the spiral groove (331), for guiding the axial sliding of the rotating guide rod (330) when the rotating guide rod (330) deflects, and the sliding rod (341) of the push head (340) is arranged in parallel with the rotating guide rod (330), for guiding the radial sliding of the push head (340) along the ring sleeve base (310); A plurality of screw sleeve bases (311) and rotating guide rods (330) are uniformly distributed along the circumferential direction of the ring sleeve base (310), the surface of the crank arm (332) is provided with a ball head pin for connecting with the end of the linkage rod (350), and the crank arms (332) of the adjacent rotating guide rods (330) are movably connected with each other through the linkage rod (350).

2. The fixture for machining the radial face of a steam turbine blade on a four- axis machine according to claim 1, characterized in that, The displacement base (100) comprises a fixed base (110), a lifting head (120), a main arm (130) and a secondary arm (140) rotatably installed on one side of the lifting head (120), the main arm (130) and the secondary arm (140) are arranged in parallel and rotatably connected with the surface of the fixed base (110) at one end, the surface of the fixed base (110) is provided with a rudder for driving the main arm (130) to deflect, and the lifting head (120) and the driving disc (200) are driven to move up and down by the deflection of the main arm (130) and the secondary arm (140).

3. The fixture for machining the radial face of a steam turbine blade on a four- axis machine according to claim 1, wherein, The driving disc (200) is provided with a core expansion clamp (230) for internally expanding and positioning the turbine blade shaft hole. The core expansion clamp (230) comprises a guide cone cylinder (231), a lead screw (232), a conical expansion block (233) and an expansion sleeve (234). The guide cone cylinder (231) is fixedly installed on the surface of the driving disc (200) at the axial position. The top end of the lead screw (232) is fixedly connected with the conical expansion block (233), and the lead screw (232) is sleeved on the inner side of the guide cone cylinder (231) and the expansion sleeve (234). The expansion sleeve (234) is slidably sleeved on the outer surface of the guide cone cylinder (231) and the conical expansion block (233).

4. The fixture for machining the radial face of a steam turbine blade on a four- axis machine according to claim 3, characterized in that, The bottom surface of the ring seat (310) is provided with a tooth ring engaged with the output end of the first driving motor (210) for transmission. The output end of the second driving motor (220) is in transmission connection with the bottom end of the lead screw (232), and the lead screw (232) is threadedly sleeved on the inner side of the guide cone cylinder (231).

5. The fixture for machining the radial face of a steam turbine blade on a four- axis machine according to claim 3, wherein, The outer surface of the guide cone cylinder (231) and the outer surface of the conical expansion block (233) are both provided with a conical surface in sliding abutment with the inner side of the expansion sleeve (234). The expansion sleeve (234) is a deformable sleeve structure.

6. The fixture for machining the radial face of a steam turbine blade on a four- axis machine according to claim 1, wherein, The surface of the clamping ring (410) is divided into a plurality of groups of deformation gaps (411) along the inner periphery and the outer periphery. Each group of deformation gaps (411) is arranged in interlaced manner and is distributed along the circumferential direction of the clamping ring (410) and located between adjacent push heads (340).

7. The fixture for machining the radial face of a steam turbine blade on a four- axis machine according to claim 1, wherein, The inner side of the clamping ring (410) is rotatably installed with a parting clamp lobe (420). The surface of the parting clamp lobe (420) is rotatably installed with an abutment (430). The parting clamp lobe (420) and the abutment (430) are both in semicircular arc columnar structure. The parting clamp lobe (420) is rotatably installed on the surface of the clamping ring (410). Two or more abutments (430) are arranged on each parting clamp lobe (420). The surface of the abutment (430) is fixedly installed with a rubber pad (431).

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