A clamping mechanism for arc milling of steam turbine blade

Abstract

The present application relates to the technical field of clamping mechanism, in particular to a clamping mechanism for arc milling of steam turbine blade, which comprises a fixed seat, a guide ring seat, a linkage plate, a pull ear lever, a horizontal slide bar, a clamping assembly, a chuck die, a taper guide, a compression ring and a drive cylinder. The drive cylinder drives the relative movement of the guide ring seat, the wedge guide surface of the pull ear lever cooperates with the pulley and the inclined slide groove cooperates with the guide slide pin to convert the axial stroke into multi-directional radial feeding, the four chuck dies form a full-wrapping cavity that is compatible with the blade root part and self-centering clamping; the taper guide and the compression ring form an inclined surface holding and secondary self-locking, and the deformation gap realizes elastic uniform pressure and damping enhancement. The clamping force of the mechanism is adjustable and convenient to change, can inhibit chatter, improve the consistency of size and surface quality and clamping safety, and is suitable for batch and automatic processing.

Description

Technical Field

[0001] This invention relates to the field of clamping mechanism technology, specifically to a clamping mechanism for arc milling of steam turbine blades. Background Technology

[0002] During CNC machining processes such as arc milling, turbine blades have thin-walled, long cantilever structures and complex root contours (such as tenons or mortise-and-tenon joints). The machining loads are alternating and pulsating, which can easily induce chatter and positional drift. To ensure machining accuracy and surface quality, it is necessary to achieve high-rigidity, high-damping, and repeatable clamping in the blade root region, while also considering tool entry space and changeover efficiency.

[0003] The existing clamping solutions mainly fall into the following categories:

[0004] (1) Positioning block + pressure plate (or lateral pressure claw): Positioning references are set on both sides of the blade root, and clamping is achieved by lateral pressure of pressure plate or wedge block. This type of structure has limited contact surface, mostly point / line contact, radial clamping is the main method, axial constraint is insufficient, uneven force is easy to cause local indentation and slight rotation of the blade root, and it is difficult to suppress high frequency flutter.

[0005] (2) Three / four jaw chuck type or four slider wedge drive type: each jaw is driven to move towards the center by external wedges or lead screws, which is more adaptable. However, each jaw is often driven separately, and the feed is not synchronized, requiring manual leveling and correction; most structures only provide radial clamping, lack axial clamping constraint on the blade root, and usually rely on continuous hydraulic pressure, which is easy to loosen when pressure is lost, thus limiting safety and repeatability.

[0006] (3) Expansion sleeve / cone sleeve type internal expansion clamping: The inner cone-outer sleeve is used to expand the blade root hole or local groove, which has high positioning accuracy. However, it has poor adaptability to the shape of the blade root, making it difficult to achieve full wrapping contact with complex outer contours. The clamping range is narrow and the changeover cost is high. At the same time, the interface damping is limited, and the effect of suppressing milling chatter is unstable.

[0007] (4) Temporary potting / vacuum adsorption assistance: The overall damping is improved by using low-melting-point alloys, resins or vacuum adsorption. This type of method involves many preparation and cleaning processes, has a long cycle, and is easily affected by chips and coolant, which limits its continuous industrial application.

[0008] In summary, existing technologies generally suffer from the following problems: ① It is difficult to achieve a large-area, fully enclosed contact with the blade root outer contour, resulting in insufficient contact stiffness and interface damping; ② Clamping execution is mostly decentralized and asynchronous, relying on manual alignment, resulting in an unclosed load path and easy occurrence of off-center loading and attitude drift during machining; ③ Most solutions lack three-dimensional locking with coordinated radial clamping and axial engagement, leading to insufficient vibration and pull-out resistance; ④ They generally lack self-locking or have weak self-locking capabilities, requiring continuous pressure maintenance, and are at risk of loosening in the event of pressure loss, machine stoppage, or impact; ⑤ They have low adaptability to different blade types and poor repeatability of clamping force, making it difficult to achieve stable batch machining of blades of various specifications. These problems directly lead to a low chatter threshold, increased surface ripples and dimensional deviations, and reduced tool life during arc milling. There is an urgent need for a clamping mechanism that can achieve full-enclosed clamping, synchronous linkage drive, and reliable self-locking function to improve the system's natural frequency and damping, stabilize the load path, and enhance machining consistency and safety. Summary of the Invention

[0009] The present invention aims to solve one of the technical problems existing in the prior art or related technologies.

[0010] Therefore, the technical solution adopted in this invention is as follows: a clamping mechanism for arc milling of steam turbine blades, including a fixed base, a guide ring base, a linkage plate, a pull rod, a transverse slide rod, a clamping assembly (including a chuck die and a tapered guide), a pressure ring, and a drive cylinder. Vertical displacement is converted into multi-directional equidistant radial feed via a wedge guide surface-pulley and pin-groove mechanism through a single axial drive, causing the chuck die to form a fully enclosed cavity adapted to the blade root and self-center and clamp. Simultaneously, axial pre-tightening and secondary self-locking are established by the inclined engagement of the tapered guide and the pressure ring, forming a three-dimensional locking system of "radial clamping + axial engagement," achieving stable clamping with high rigidity, high damping, and high repeatability.

[0011] Specifically, it includes: a fixed base; a guide ring base with a transverse and longitudinal sliding groove on its inner side; a linkage plate; several pull rods, the lower ends of which are rotatably connected to the linkage plate and slide vertically along the longitudinal sliding groove; several transverse sliding rods that slide radially along the transverse sliding groove and are sleeved on the surface of the corresponding pull rod; a clamping assembly, including several chuck molds and a conical guide fixed to the bottom surface of the chuck mold; a pressure ring that is slidably sleeved on the outer surface of the conical guide; a pulley and a guide pin are provided on the inner side of the transverse sliding rod, and a wedge guide surface is formed on the surface of the pull rod and an oblique sliding groove is opened, the pulley and the wedge guide surface are in rolling engagement, and the guide pin and the oblique sliding groove are in sliding engagement; a drive cylinder drives the guide ring base and the fixed base to make relative linear motion.

[0012] The single axial stroke is converted into four-way equidistant radial feed, realizing self-centering clamping and synchronous approach at the blade root; the pulley-wedge surface and pin-groove composite guide ensures transmission efficiency and kinematic coupling accuracy, establishes a stable and closed force path, and suppresses off-center load and position drift.

[0013] In a preferred embodiment, the wedge angle of the wedge guide surface is 5°–15°, the pulley uses needle roller or grooved roller bearings, and the clearance between the oblique groove and the guide pin is controlled at 0.02–0.08 mm to balance sensitive transmission and anti-side sway. The wedge angle is smaller than the self-locking angle and the rolling friction is low, which reduces drive load and wear, and ensures stable clamping under cutting reaction force. Four chuck dies are used, arranged in pairs facing each other. The four chuck dies combine to form a cavity that conforms to the shape of the blade root. This creates a large-area, fully enclosed clamping structure, homogenizing contact stress and clamping load, improving contact stiffness and interface damping, significantly suppressing high-frequency chatter, and reducing the risk of local indentation at the blade root.

[0014] In a preferred embodiment, the inner forming surface of the chuck mold uses replaceable liner blocks, and the three-sided positioning of the reference surface maintains the consistency of the cavity after mold change. This enables rapid mold change and repeatable positioning across specifications, improving the consistency and economy of batch processing. The conical guide assembly forms an annular conical ring structure. The outer surface of the conical guide has an inclined conical surface that mates with the inner side of the pressure ring, and several deformation gaps are evenly distributed along the circumference of the outer wall of the conical guide. The inclined surface mating between the pressure ring and the inclined conical surface provides axial clamping support while clamping radially, establishing a three-dimensional locking; the deformation gaps provide a small amount of radial elasticity, homogenizing the clamping force in all directions, increasing interface damping, and reducing micro-vibration peaks.

[0015] In a preferred example, the cone angle of the inclined cone surface is 10° to 25°; the deformation gap width is 0.5 to 1.5 mm and the depth is 60% to 90% of the outer wall thickness; the surface roughness Ra of the mating surface between the pressure ring and the inclined cone surface is 0.8 to 1.6 μm.

[0016] Specific technical effects: achieving controllable preload and stable friction coefficient, ensuring long-term consistency of clamping stiffness and damping.

[0017] In a preferred embodiment, the drive cylinder is further configured such that it is fixedly mounted on the surface of the linkage plate. The drive cylinder is used to drive the guide ring seat and the fixed seat to make relative linear motion. The drive cylinder can be a hydraulic cylinder or a linear push rod.

[0018] Technical benefits: Multi-directional synchronous clamping is achieved with a single actuator. The system has a simple configuration, high reliability, and the clamping stroke and force can be precisely controlled.

[0019] In a preferred example, the configuration is further as follows: when using a hydraulic cylinder, the maximum clamping force is limited by an overflow valve; when using a linear electric actuator, the maximum clamping force is controlled by both current limiting and limit switches.

[0020] Specific technical effects: Avoid overload and under-tightening, improve clamping force repeatability and clamping safety.

[0021] In a preferred example, the lug rods and the horizontal slide rods are of the same number and correspond one-to-one. The lower end of the lug rod is rotatably connected to the linkage plate via a pivot, and the upper end passes through the fixed seat and extends into the guide ring seat.

[0022] Technical benefits: Ensures synchronization and mechanical symmetry of four-way feed, reduces system eccentricity and lateral sway, and improves self-centering accuracy and stability.

[0023] In a preferred example, the shaft is further configured with a replaceable bushing and taper pin for positioning to maintain long-term fit accuracy.

[0024] Specific technical effects: Reduces synchronization errors caused by wear gap accumulation and extends service life.

[0025] In a preferred example, the pulley is further configured as follows: the pulley is a roller structure that can rotate about an axis, and the wedge guide surface is inclined relative to the axis of the pull rod to convert the vertical displacement of the pull rod into the radial displacement of the horizontal slide rod.

[0026] Technical benefits: It achieves high-efficiency displacement conversion and force amplification, and reduces frictional heat generation and jamming risks; the wedge angle design enables the system to have self-locking capability under stress.

[0027] In a preferred example, the wedge guide surface is further configured such that the contact angle between the guide surface and the pulley is less than the self-locking angle and is surface hardened, and solid lubrication points are added to the mating surfaces.

[0028] Specific technical effects: It maintains a clamped state continuously during processing and suppresses clamping slack caused by high-frequency vibration during processing.

[0029] In a preferred example, the chuck mold and the corresponding slide bar are further configured to be detachably fixed by means of a positioning step surface and a connecting screw.

[0030] Technical benefits: Enables quick assembly and disassembly of the chuck mold and specification changes, while ensuring clamping rigidity and maintaining consistency of dimensional references.

[0031] In a preferred example, the positioning step is combined with a positioning pin for positioning, and the screws employ an anti-loosening structure. This accelerates changeover cycles and prevents micro-displacement due to machining vibration.

[0032] In a preferred embodiment, the pressure ring is further configured as follows: the pressure ring is an annular part and is slidably disposed along the axial direction of the tapered guide, and the fixing seat is provided with limiting or fastening holes evenly distributed in the circumferential direction to limit or fasten the pressure ring.

[0033] Technical effect: By adjusting the clamping preload of the inclined cone surface through the position and tightness of the pressure ring, a secondary self-locking and adjustable preload mechanism is established.

[0034] In a preferred embodiment, an adjustable shim or eccentric limiting pin is provided between the fixed seat and the pressure ring. This enables rapid matching of different materials and cutting loads, stabilizes the machining window, and extends tool life.

[0035] The beneficial effects achieved by this invention are as follows:

[0036] 1. In this invention, a fully enclosed cavity adapted to the shape of the blade root is formed by a chuck mold, and together with the tapered guide and pressure ring, a three-dimensional locking system is formed that coordinates radial clamping and axial engagement. The clamping interface has a large surface contact area, uniform load distribution, and significantly improved contact stiffness and friction damping. This effectively suppresses high-frequency chatter during arc milling, reduces blade deformation and springback, and improves surface quality and dimensional stability. At the same time, by changing the inner forming surface of the chuck mold, it can be adapted to blade roots of different specifications, exhibiting good versatility and ease of changeover.

[0037] 2. This invention employs the synchronous action of the transverse slide bar and the pressure ring, combined with the wedge-wheel transformation and pin-groove guiding mechanism of the linkage plate and pull rod, to transform the single axial drive into multi-directional equidistant radial feed, achieving self-centering clamping and four-way synchronous approach of the blade root. This linkage closed force path reduces off-center load and clamping errors, has high clamping force repeatability, and significantly improves clamping efficiency and positioning consistency. The preload can be precisely set through the adjustable design of stroke and limit to match different materials and cutting load conditions, extending tool life and improving machining stability.

[0038] 3. This invention has a self-locking characteristic: the mating angle between the wedge guide surface and the roller is smaller than the self-locking angle, and the inclined friction between the superimposed tapered guide and the pressure ring provides self-locking, which can maintain the clamping state under power failure or pressure loss, and prevent loosening and position drift caused by processing vibration; the wedge effect of tightening with load reduces the dependence on continuous pressure holding, improves clamping safety and reliability, and is suitable for continuous batch processing and long cycle automated production. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the overall structure of one embodiment of the present invention;

[0040] Figure 2 This is an exploded structural diagram of an embodiment of the present invention;

[0041] Figure 3 This is a schematic diagram of the linkage plate, pull rod, and drive cylinder structure according to an embodiment of the present invention;

[0042] Figure 4 This is a partial cross-sectional structural diagram of an embodiment of the present invention;

[0043] Figure 5 This is a schematic diagram of the linkage plate and clamping assembly structure according to an embodiment of the present invention;

[0044] Figure 6 This is a schematic diagram of the horizontal sliding rod and the pull lug rod according to an embodiment of the present invention;

[0045] Figure 7 This is a schematic diagram of a clamping component structure according to an embodiment of the present invention;

[0046] Figure 8 This is a schematic diagram of a clamping assembly according to an embodiment of the present invention and a turbine blade structure in the prior art.

[0047] Figure label:

[0048] 100. Fixture;

[0049] 200. Guide ring seat; 210. Horizontal slide bar; 211. Pulley; 212. Guide pin;

[0050] 300. Linkage plate; 310. Pulling rod; 320. Drive cylinder; 311. Wedge guide surface; 312. Inclined slide groove;

[0051] 400 Clamping assembly; 410 Chuck mold; 420 Conical guide; 421 Inclined conical surface; 422 Deformation gap;

[0052] 500, turbine blade; 510, blade root. Detailed Implementation

[0053] 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.

[0054] It should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the invention.

[0055] The following describes, with reference to the accompanying drawings, a clamping mechanism for arc milling of turbine blades provided by some embodiments of the present invention.

[0056] Combination Figures 1-8 As shown, the present invention provides a clamping mechanism for arc milling of steam turbine blades, including a fixed base 100, a guide ring base 200, a linkage plate 300, a pull rod 310, a horizontal slide rod 210, a clamping assembly 400, a pressure ring 110, and a drive cylinder 320.

[0057] The fixed base 100 is used for positioning and connecting with the CNC machine tool worktable. Several fastening holes are provided circumferentially on the upper surface of the fixed base 100 for limiting or fastening the pressure ring 110. A through window is provided in the middle of the fixed base 100 to facilitate the engagement and up-and-down movement of the bottom end of the tapered guide 420 with the pressure ring 110.

[0058] The guide ring seat 200 is positioned above the fixed seat 100 and connected to the drive cylinder 320. The inner side of the guide ring seat 200 is provided with two types of guide structures: one is a transverse sliding groove extending radially, used to guide the transverse sliding rod 210 radially; the other is a longitudinal sliding groove extending vertically, used to guide the pull rod 310 vertically.

[0059] The linkage plate 300 is located below or to the side of the fixed base 100 and is fixed relative to the fixed base 100 by a support. The lower end of the pull rod 310 is rotatably connected to the linkage plate 300 by a pivot, and the upper end passes through the fixed base 100 and extends into the guide ring seat 200. It can make vertical reciprocating motion in the longitudinal groove of the guide ring seat 200. The outer surface of the pull rod 310 forms a wedge guide surface 311, and an oblique groove 312 is opened on its body for cooperating with the guide pin 212 of the horizontal slide rod 210.

[0060] The horizontal slide bar 210 slides radially along the transverse groove of the guide ring seat 200. A pulley 211 is rotatably mounted on the inner side of the horizontal slide bar 210. The pulley 211 rolls with the wedge guide surface 311 on the pull lug 310 to convert the vertical displacement of the pull lug 310 into the radial displacement of the horizontal slide bar 210. A guide pin 212 is fixed on the horizontal slide bar 210. The guide pin 212 is slidably embedded in the inclined groove 312 of the pull lug 310 to limit the movement trajectory of the horizontal slide bar 210 and correct multi-directional synchronization.

[0061] The clamping assembly 400 is fixed to the inner end of the horizontal slide bar 210. The clamping assembly 400 includes a chuck mold 410 and a tapered guide 420 fixed to the bottom surface of the chuck mold 410. The four chuck molds 410 are arranged in pairs facing each other (see...). Figure 7 , Figure 8 The components are combined to form a cavity that conforms to the shape of the turbine blade root 510. The outer surface of the tapered guide 420 forms a sloping tapered surface 421, and the bottom ends of multiple tapered guides 420 are combined to form an annular tapered ring structure, which is arranged through the central opening of the fixed seat 100. The pressure ring 110 is an annular component that is fitted from top to bottom onto the outer side of the tapered guide 420 and is limited or locked to the fixed seat 100 by fasteners.

[0062] The drive cylinder 320 is fixedly mounted on the linkage plate 300, and its output end is connected to the bottom surface of the guide ring seat 200, used to drive the guide ring seat 200 to make relative linear motion with the fixed seat 100. The drive cylinder 320 can be a hydraulic cylinder or a linear electric push rod.

[0063] In this embodiment, the chuck mold 410 and the horizontal slide bar 210 are fitted by a positioning step surface and are detachably fixed by connecting screws, so as to replace different inner forming surfaces to adapt to different specifications of blade root 510.

[0064] In this embodiment, to achieve reliable self-centering and self-locking, it is preferable that the wedge guide surface 311 of the pull rod 310 forms a wedge angle of 5° to 15° relative to the axis of the pull rod; under steel-to-steel dry friction conditions, the wedge angle is preferably not greater than the self-locking angle to ensure that no reverse slippage occurs under processing load. The pulley 211 is selected from grooved roller bearings or needle bearing roller structures to reduce rolling friction and improve force transmission efficiency.

[0065] In a preferred embodiment, the tapered surface 421 of the tapered guide 420 has a cone angle of 10° to 25° relative to the axis; deformation gaps 422 are evenly distributed circumferentially on the outer wall of the tapered guide 420, with a width of 0.5 to 1.5 mm and a depth of 60% to 90% of the outer wall thickness, to provide a small amount of radial elasticity to homogenize the clamping force and improve the interface damping. The mating surface between the inner hole of the pressure ring 110 and the tapered surface 421 is machined into a ground or precision-milled surface, with a surface roughness preferably Ra 0.8 to 1.6 μm.

[0066] In a preferred embodiment, the transverse slide bar 210 and the guide ring seat 200 are further configured such that the transverse slide groove adopts a rectangular slider and a guide rail pair with adjustable gap, the adjustable gap range being 0.01 to 0.05 mm; the longitudinal slide groove of the pull rod 310 and the guide ring seat 200 has a clearance of 0.02 to 0.08 mm to balance sensitive transmission and resistance to lateral swaying.

[0067] In this embodiment, the assembly sequence is as follows: First, the fixed seat 100 is matched with the positioning pin hole of the machine tool worktable and tightened with bolts; second, the linkage plate 300 is installed below the fixed seat 100 and connected to the machine tool table or special support; then, the lower end of the pull rod 310 is rotatably connected to the linkage plate 300 through the pin shaft, and the upper end passes through the fixed seat 100 and is inserted into the longitudinal slide groove of the guide ring seat 200; subsequently, the transverse slide rod 210 is installed into the transverse slide groove of the guide ring seat 200, and the pulley 2 on the inner side of the transverse slide rod 210 is... Align the wedge guide surface 311 of the pull rod 310 with the guide pin 212, and insert the guide pin 212 into the inclined slide groove 312; then fix the chuck mold 410 and the horizontal slide rod 210 with the positioning step and screws, and connect the tapered guide 420 and the chuck mold 410 with the positioning pin and screws; finally, fit the pressure ring 110 from the top to the outside of the tapered guide 420 and limit or lock it through the fastening hole on the fixing seat 100, and install the drive cylinder 320 on the linkage plate 300 and connect it to the bottom surface of the guide ring seat 200 to complete the assembly.

[0068] In a preferred example, the chuck mold 410 is further configured such that, for ease of changeover, the inner forming surface of the chuck mold 410 adopts a replaceable liner structure. The liner material can be aluminum bronze or resin-coated metal to balance contact stiffness and surface damping. The reference surface of the chuck mold 410 adopts three-sided positioning to ensure the consistency of the cavity reference after changeover.

[0069] In this embodiment, the usage process is as follows:

[0070] In the initial state, the drive cylinder 320 separates the guide ring seat 200 from the fixed seat 100, the transverse slide bar 210 is in a radially outward position, and the pressure ring 110 is located above the tapered guide member 420. The operator places the blade root 510 of the turbine blade 500 above the cavity formed by the four chuck molds 410 and performs rough positioning. The drive cylinder 320 extends, the guide ring seat 200 moves vertically away from the fixed seat 100, and the pull rod 310 moves upward in the longitudinal groove; the wedge guide surface 311 pushes the pulley 211 to roll inward, and the transverse slide bar 210 moves radially inward in the transverse groove simultaneously, driving the chuck mold 410 to move closer to the blade root 510, achieving self-centering clamping. As the chuck mold 410 continues to move inward, the tapered guide member 420 is pressed down into the pressure ring 110, and the inclined cone surface 421 and the inner side of the pressure ring 110 form an inclined surface fit, obtaining axial clamping support and forming a three-dimensional locking. After processing, the drive cylinder 320 returns, the guide ring seat 200 and the fixed seat 100 move closer to each other, the pull rod 310 moves down, the wedge guide surface 311 drives the pulley 211 to roll in the opposite direction, the horizontal slide rod 210 moves outward radially, the chuck mold 410 opens, the cone guide 420 moves up relative to the pressure ring 110 to release the clamping, and the blade can be taken out smoothly.

[0071] In this embodiment, to ensure synchronous four-way clamping and improve vibration resistance, the pull rods 310 and the cross slide rods 210 are arranged in a one-to-one correspondence and are the same in number. The contact angle between the wedge guide surface 311 of the pull rod 310 and the pulley 211 is smaller than the self-locking angle, ensuring that there will be no reverse sliding due to reaction force under the action of machining load. The frictional fit between the pressure ring 110 and the inclined cone surface 421 provides secondary self-locking to avoid the attenuation of clamping force during machining. The fit between the guide pin 212 and the inclined slide groove 312 restricts the undesired degrees of freedom of the cross slide rod 210, preventing the cross slide rod 210 from wobbling or rebounding under the action of cutting reaction force.

[0072] In a preferred example, the clamping force can be further configured such that when the drive cylinder 320 is a hydraulic cylinder, the upper limit of the clamping force can be set by the hydraulic system relief valve; when a linear electric push rod is used, the clamping force and stroke can be repeatedly matched by dual control of current limiting and limit switch.

[0073] In another example, an adjustable shim or eccentric limiting pin is provided between the pressure ring 110 and the fixed seat 100 to finely adjust the relative position of the inclined cone surface 421 and the pressure ring 110, thereby setting the clamping preload.

[0074] In another example, the number of chuck molds 410 can be selected between 3 and 6 depending on the shape and size of the leaf root 510, with four being preferred to achieve symmetrical clamping and ease of processing.

[0075] In this embodiment, the fixed seat 100 and the guide ring seat 200 are preferably made of high-strength cast iron or cast steel and subjected to aging treatment to improve the base damping and dimensional stability; the transverse slide bar 210, the pull rod 310 and the chuck mold 410 are preferably made of tempered alloy steel and the working surface is hardened; the mating surface of the inclined cone surface 421 and the pressure ring 110 can be nitrided or hard chrome plated to reduce wear and maintain a stable coefficient of friction; the transition fillet at the deformation gap 422 is R0.5~1.0 to avoid stress concentration.

[0076] Working principle and usage process of this invention:

[0077] Combination Figures 1-8 As shown, the clamping mechanism for arc milling of turbine blades of the present invention mainly consists of a fixed base 100, a guide ring seat 200, a linkage plate 300, a pull rod 310, a horizontal slide rod 210, a clamping assembly 400 (including a chuck mold 410 and a tapered guide 420), a pressure ring 110, and a drive cylinder 320. Its clamping-locking-machining-unlocking action and force path conversion mechanism are as follows.

[0078] In the initial state, the fixed seat 100 is fixed on the CNC machining tool, and the output end of the drive cylinder 320 is fixed to the bottom surface of the guide ring seat 200. Then, the drive cylinder 320 performs work to make the guide ring seat 200 move relatively away from the surface of the fixed seat 100.

[0079] The drive cylinder 320 positions the guide ring seat 200 and the fixed seat 100 in contact. The upper end of the pull rod 310 is located in the longitudinal groove of the guide ring seat 200 and can slide vertically. The lower end is rotatably connected to the linkage plate 300 via a pivot. The transverse slide rod 210 is in a radially outward position in the transverse groove of the guide ring seat 200. The chuck mold 410 moves outward with the transverse slide rod 210 to form a cavity to be clamped. The pressure ring 110 is sleeved on the outer surface of the tapered guide member 420 near the upper end. The operator positions the blade root 510 of the turbine blade 500 from top to bottom above the cavity formed by the four chuck molds 410.

[0080] The drive cylinder 320 extends, causing the guide ring seat 200 to move vertically away from the fixed seat 100. Subsequently, the pull rod 310 undergoes vertical displacement relative to the transverse slide rod 210: the wedge guide surface 311 on the surface of the pull rod 310 rolls into contact with the pulley 211 on the inner side of the transverse slide rod 210, converting the vertical displacement of the pull rod 310 into radial inward movement of the transverse slide rod 210 within the transverse groove of the guide ring seat 200; simultaneously, the guide pin 212 on the transverse slide rod 210 slides within the inclined groove 312 of the pull rod 310, restricting the movement trajectory of the transverse slide rod 210 and correcting the four-way synchronization.

[0081] Under the combined action of the wedge-wheel drive and pin-groove guide, multiple horizontal slide bars 210 drive the corresponding chuck molds 410 to approach the blade root 510 in an equidistant and synchronous manner. The inner forming surface of the chuck mold 410 matches the outer shape of the blade root 510, thereby achieving self-centering clamping of the blade root 510.

[0082] As the chuck mold 410 continues to move inward, the tapered guide 420 fixed at its bottom end is pressed downward into the pressure ring 110. The inclined tapered surface 421 on the outer surface of the tapered guide 420 and the inner surface of the pressure ring 110 generate a normal clamping force with inclined surface engagement. This normal force, on the one hand, supports the chuck mold 410 upward under the action of the component force of the inclined tapered surface 421, so that the chuck mold 410 obtains axial upward clamping support while being radially clamped; on the other hand, it forms a circumferential closed force path through the pressure ring 110 and the fixed seat 100, so that the load path of "chuck mold 410 - transverse slide bar 210 - pull rod 310 - guide ring seat 200 - fixed seat 100" is stably closed. The deformation gap 422 provided circumferentially on the outer wall of the tapered guide 420 allows it to generate a small amount of radial elastic deformation, thereby homogenizing the clamping force in all directions, absorbing micro-vibrations and improving interface damping.

[0083] When the drive cylinder 320 reaches the set stroke, the wedge guide surface 311 of the pull rod 310 and the pulley 211 form a contact state with an angle smaller than the self-locking angle. The vertical reaction force of the pull rod 310 is decomposed into the radial clamping force and guiding force of the transverse slide rod 210 through the wedge guide surface 311, realizing wedge self-locking. At the same time, the frictional fit between the pressure ring 110 and the inclined cone surface 421 constitutes secondary self-locking. During the machining process, the cutting load applied by the tool to the turbine blade 500 is transmitted to the chuck die 410 through the blade root 510: the radial component is borne by the transverse slide rod 210 and the pull rod 310 and transmitted to the guide ring seat 200 and the fixed seat 100; the axial component is borne by the coupling of the inclined cone surface 421 and the pressure ring 110 and transmitted to the fixed seat 100. The cooperation between the guide pin 212 and the inclined slide groove 312 prevents the transverse slide rod 210 from swaying or rebounding under the action of cutting force, ensuring the stability of the clamping posture.

[0084] During the clamping and holding phase, four-way equidistant clamping creates surface contact support between the blade root 510 and the chuck mold 410. The tapered guide 420 and the inclined surface of the pressure ring 110 engage to form axial preload. Together, they constitute a three-dimensional locking system of "radial clamping + axial engagement". The micro-elasticity provided by the deformation gap 422, together with the friction of the clamping interface, forms additional damping. Combined with the closed force path, this suppresses high-frequency chattering of the blade body during arc milling, improving the system modal frequency and disturbance rejection under operating conditions.

[0085] After machining, the drive cylinder 320 reverses its movement, the guide ring seat 200 moves in the opposite direction relative to the fixed seat 100 and moves closer to each other, the pull rod 310 returns along the longitudinal slide groove, the wedge guide surface 311 drives the pulley 211 to roll in the opposite direction, the transverse slide rod 210 retracts radially outward, and the chuck mold 410 opens accordingly; the tapered guide 420 moves upward relative to the pressure ring 110 along the inclined tapered surface 421, releasing the axial clamping. At this time, the turbine blade 500 can be smoothly removed from the cavity, and the clamping cycle is completed.

[0086] By changing the inner forming surface of the chuck mold 410, different specifications of blade root 510 can be adapted; by adjusting the stroke of the drive cylinder 320 or limiting the pressure ring 110 on the fixed seat 100, the mating position of the inclined cone surface 421 and the pressure ring 110 can be adjusted, thereby setting the clamping force and the holding preload, and realizing rapid matching for different materials and cutting loads.

[0087] 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.

[0088] 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 clamping mechanism for arc milling of steam turbine blades, characterized in that, include: Fixed base (100), guide ring base (200), linkage plate (300) and clamping assembly (400); The surface of the linkage plate (300) is rotatably mounted with a plurality of pull rods (310), each pull rod (310) sliding vertically through the fixed seat (100) and extending upward to the inner side of the guide ring seat (200); the inner side of the guide ring seat (200) is slidably mounted with a plurality of radially arranged transverse slide rods (210), each transverse slide rod (210) slidingly sleeved on the surface of the corresponding pull rod (310); the surface of the linkage plate (300) is fixedly mounted with a drive cylinder (320), the two ends of the drive cylinder (320) being connected to the guide ring seat (200) and the fixed seat (100) respectively, for driving the guide ring seat (200) and the fixed seat (100) to make relative linear motion, the drive cylinder (320) being either a hydraulic cylinder or a linear push rod; The clamping assembly (400) includes a plurality of chuck molds (410) and a conical guide (420) fixed to the bottom surface of each chuck mold (410). Each chuck mold (410) is detachably installed at one end of the corresponding horizontal slide bar (210). The bottom ends of each conical guide (420) are combined to form an annulus and are disposed through the upper surface of the fixed base (100). A pressure ring (110) is fixedly installed on the upper surface of the fixed seat (100), and the pressure ring (110) is slidably sleeved on the outer surface of the cone guide (420); the inner side of the guide ring seat (200) is respectively provided with a transverse groove for guiding the radial sliding of the transverse slide rod (210) and a longitudinal groove for guiding the vertical sliding of the pull rod (310).

2. The clamping mechanism according to claim 1, characterized in that, The number of the chuck molds (410) is four, arranged in pairs opposite each other. The cavity formed by the combination of the four chuck molds (410) is adapted to the shape of the root (510) of the turbine blade.

3. The clamping mechanism according to claim 1, characterized in that, The conical guide (420) is assembled to form a conical ring structure. The outer surface of the conical guide (420) is provided with an inclined conical surface (421) that matches the inner side of the pressure ring (110). The wall of the conical guide (420) is uniformly provided with a number of deformation gaps (422) along the circumferential direction.

4. The clamping mechanism according to claim 1, characterized in that, The number of the pull rods (310) is the same as the number of the horizontal slide rods (210) and they correspond one-to-one. The lower end of each pull rod (310) is rotatably connected to the linkage plate (300) by means of a rotating shaft, and the upper end passes through the fixed seat (100) and extends into the guide ring seat (200) in sequence.

5. The clamping mechanism according to claim 1, characterized in that, The inner side of the horizontal slide bar (210) is provided with a pulley (211) and a guide pin (212); the surface of each pull rod (310) is provided with a wedge guide surface (311) that slides against the pulley (211), and an inclined groove (312) is provided on the pull rod (310), and one end of the guide pin (212) is slidably embedded in the inclined groove (312).

6. The clamping mechanism according to claim 5, characterized in that, The wedge guide surface (311) is inclined relative to the axis of the pull rod (310) to convert the vertical displacement of the pull rod (310) into the radial displacement of the horizontal slide rod (210).

7. The clamping mechanism according to claim 1, characterized in that, Each of the clamp molds (410) and the corresponding horizontal slide bar (210) are detachably fixed by a positioning step surface and a connecting screw.

8. The clamping mechanism according to claim 1, characterized in that, The pressure ring (110) is an annular part and is slidably arranged along the axial direction of the tapered guide (420). The fixing seat (100) is provided with fastening holes evenly distributed in the circumferential direction for limiting or fastening the pressure ring (110).

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