Variable supporting clamp for large-bypass-ratio fan blade and automatic polishing method
By using a variable support fixture for high-bypass fan blades and an automatic polishing method, the problems of polishing chatter and uncontrollable removal amount during the repair of high-bypass engine fan rotor blades have been solved, realizing automatic polishing and efficient repair of the entire surface and improving polishing quality and efficiency.
Patent Information
- Application Number
- CN202511306815.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-12
- Publication Date
- 2025-11-14
AI Technical Summary
During the repair of the fan rotor blades of the high bypass ratio engine, the positioning reference at the blade tip was removed, which caused chatter during polishing in the area near the blade tip. The waviness after polishing was not up to standard, and the amount of material removed was uncontrollable. The polishing efficiency of the damping table and the blade root transition area was low.
By employing a variable support fixture and automatic polishing method for high bypass ratio fan blades, utilizing tenon clamping and a variable support structure at the blade tip, combined with a seven-axis linkage CNC belt grinder, and using a dual-grinding head system with floating sanding belt and floating nylon wheel, automatic polishing of the entire blade profile is achieved, solving the problem of blade tip polishing chatter and ensuring full coverage.
It has achieved automatic polishing of the entire surface of large-size fan blades, with a roughness of Ra0.4um after polishing, which improves polishing efficiency by more than 30%, reduces equipment resource waste, and meets repair requirements.
Smart Images
Figure CN120941280A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a variable support fixture and automatic polishing method for high bypass ratio fan blades, belonging to the field of aero-engine blade repair, and is particularly suitable for automatic polishing and repair of high bypass ratio engine fan rotor blades during blade repair. Background Technology
[0002] The overhaul process of high bypass ratio engines requires polishing and troubleshooting of the blade profile. Because the fan rotor blades are large (generally ≥500mm in the height direction), manual repair is not possible. Only automatic polishing methods can be used for repair. The current automatic polishing repair method generally uses a CNC belt grinder to hold the blade tenon for automatic polishing repair. The following problems exist when polishing large-size fan rotor blades: (1) The positioning reference at the blade tip has been removed during the repair. Because the blade is large in the height direction, there is chatter when polishing near the blade tip area. The waviness is not qualified after polishing, and the vibration has an adverse effect on the blade root area; (2) Because the blade is large in the height direction, the deviation between the actual position of the blade near the blade tip and the theoretical position is amplified, resulting in uncontrollable removal during polishing; (3) The polishing efficiency and effect of the damping table and blade root transition area are low. Summary of the Invention
[0003] This invention provides a variable support fixture for large-size fan rotor blades. By utilizing tenon clamping and a variable support structure at the blade tip, it solves the problem of blade tip polishing flutter, eliminates the influence of missing blade tip reference, and addresses the challenge of achieving full coverage of the blade tip clamping area during automatic polishing. Through the fixture and automatic polishing method of this invention, automatic polishing of the entire profile of large-size fan blades can be completed without manual polishing intervention, solving the problem of polishing and repairing large-size fan blades. This is of great significance for developing the equipment repair capabilities of high-bypass turbofan engines.
[0004] The present invention provides a blade tenon clamping and blade tip variable support structure that can automatically change the support position during the polishing process without affecting the support effect. It solves the polishing chatter problem caused by the lack of support at the blade tip and ensures that no polishing dead corners are left during the support process. The repeatability of clamping near the blade tip is controlled within ±0.05mm. The innovative use of a floating sanding belt + floating nylon wheel dual grinding head system enables one clamping and one machine to complete the polishing of the entire surface of the blade body, inlet and outlet sides, damping table and blade root junction.
[0005] This invention is achieved through the following technical solution:
[0006] An automatic polishing method for high bypass ratio fan blades is implemented on a seven-axis CNC belt grinding machine. The seven axes include X / Y / Z / A / B / C and a normal pressure axis. The grinding machine is a dual-head system. One grinding head is a floating belt grinding system, with control parameters including linear velocity, feed rate, and polishing pressure, to polish the blade body and inlet / outlet edges. The other grinding head is a floating nylon wheel system, with control parameters including linear velocity, feed rate, and polishing pressure, to polish the damping table and blade root transition area. The method includes the following steps:
[0007] 1) Design of blade clamping system: On the CNC belt grinder base 11, a tenon fixing clamp 7 and a blade tip support system are designed. The blade tip support system includes a fixed tailstock 1, an upper cylinder 2 with a guide rod and a lower cylinder 10. The fixed tailstock 1 contains a rotating shaft 12 coaxial with the machine tool A axis. The rotating shaft 12 realizes the synchronous rotation of the upper cylinder 2 and the lower cylinder 10 with the A axis during the polishing process through a bearing system. The upper cylinder 2 and the lower cylinder 10 can be controlled to tighten and loosen respectively. The control commands are integrated into the machine tool program and panel. The top block 3 that contacts the blade is made of polytetrafluoroethylene to prevent damage to the blade.
[0008] 2) Blade tenon fixing: Insert blade 5 into tenon fixing clamp 7, 9 is positioning pin, 8 is anti-misalignment pin, to prevent blade from being installed backwards, and press the blade tight;
[0009] 3) Automatic blade tip clamping: The blade 5 is clamped by the clamping command of the upper cylinder 2 and the lower cylinder 10;
[0010] 4) Automatic polishing of the blade body and inlet / outlet edges: Four pairs of floating belt abrasive heads are used for rough polishing of the blade body using P280 hollow sphere abrasive belts. The polishing parameters are: linear velocity (10-15) m / s, feed rate (3000-5000) mm / min, and pressure (3-5) N. Then, nylon belts are used for fine polishing with the following parameters: linear velocity (6-8) m / s, feed rate (2000-3000) mm / min, and pressure (2-4) N. When polishing the blade tip area, the program segment adds the release and tightening of the guide cylinder. When the sanding belt floating grinding head 4 approaches the interference area of the upper cylinder 2 during the polishing process, the program segment releases the upper cylinder 2 in advance. At this time, the lower cylinder 10 remains in a tightened state. When polishing reaches the interference area of the lower cylinder 10 while moving away from the interference area of the upper cylinder 2, the pneumatic 2 is tightened, and then the lower cylinder 10 is released. When polishing other areas except the blade tip, both the upper cylinder 2 and the lower cylinder 10 are in a tightened state.
[0011] 5) Automatic polishing of the transition area: The damping table, blade root transition area, and air intake / exhaust edge area are polished using a floating nylon wheel grinding head 6. The floating nylon wheel grinding head 6 can float along the Z-axis and achieve pressure control. The nylon wheel is driven to rotate by a motor. The nylon wheel grinding head uses a 200-mesh silicon carbide wheel. The nylon wheel grinding head is equipped with a dresser. Before polishing, the nylon wheel is dressed to match the shape of the transition R. The program is adjusted according to the size of the dressed nylon wheel. The polishing parameters are: linear speed of (6~10) m / s, feed rate of (2000~3000) mm / min, and pressure of (2~3) N.
[0012] In step 4), the blade body and inlet / outlet edges are automatically polished. The abrasive belt can be selected according to the degree of blade damage. If the blade body faults are divided into three types from major to minor—severe damage, minor damage, and slight damage—different process methods can be selected: For slight damage, the blade body can be polished directly with nylon abrasive belts; for severe damage, rough polishing can be done with stacked abrasive belts, followed by fine polishing with nylon belts; for slight damage, the blade body can be polished with floating nylon wheel grinding heads; for the inlet / outlet edges, if the damage is severe, a floating polishing system with nylon wheels is used; if the damage is slight, nylon abrasive belts are used for direct polishing; when polishing the blade body area near the blade tip, a blade tip support system is used, and the support position is automatically changed when there is interference between the grinding head and the fixture.
[0013] A variable support fixture for high bypass ratio fan blades includes a tenon fixing fixture 7 and a blade tip support system. The blade tip support system includes a fixed tailstock 1, an upper cylinder 2 with a guide rod, and a lower cylinder 10. The fixed tailstock 1 contains a rotating shaft 12 coaxial with the A-axis of the machine tool. The rotating shaft 12 achieves synchronous rotation of the upper cylinder 2 and the lower cylinder 10 with the A-axis during the polishing process through a bearing system. The upper cylinder 2 and the lower cylinder 10 can be controlled to tighten and loosen respectively. The control commands are integrated into the machine tool program and panel. The top block 3 that contacts the blade is made of polytetrafluoroethylene to prevent damage to the blade. The tenon fixing fixture 7 has a tenon groove for inserting the blade tenon and can be clamped manually or pneumatically.
[0014] The tenon fixing clamp 7 is equipped with a positioning pin 9 for positioning the blade tenon and an anti-misalignment pin 8 to prevent the blade from being installed backwards.
[0015] This invention enables automated polishing and repair of large-sized fan blades with varying degrees of damage across all areas using a single device and in a single setup. It requires no manual polishing intervention and achieves a surface roughness of Ra0.4µm, meeting blade repair requirements. The application of a dual-grinding-head system increases polishing efficiency by over 30% while reducing equipment resource waste, thus achieving the goal of improving both quality and efficiency. Attached Figure Description
[0016] Figure 1 This is an isometric view of the fixture;
[0017] Figure 2 The fixture is shown in the front view.
[0018] Figure 3 This is a sectional view of the fixed tailstock. Detailed Implementation
[0019] This invention is implemented on a seven-axis CNC belt grinding machine. The seven axes include X / Y / Z / A / B / C and a normal pressure axis. A blade support fixture is designed on the machine tool to support the blade tip during polishing, ensuring that the amount of material removed and the surface quality are controllable. The grinding machine is a dual-head system. One grinding head is a floating belt grinding system with control parameters including linear velocity, feed rate, and polishing pressure, which polishes the blade body and the inlet and outlet edges. The other grinding head is a floating nylon wheel system with control parameters including linear velocity, feed rate, and polishing pressure, which polishes the damping table, blade root, and other transition areas. The implementation steps of the fixture and automatic polishing method of this invention are shown in steps (1) to (5).
[0020] (1) Design of blade clamping system. The design uses the tenon as the main positioning position and the blade tip support as the auxiliary positioning position. The blade tip pneumatic clamp uses a variable support scheme, which can change the support position during the polishing process. The tenon can be tightened manually or pneumatically.
[0021] (2) Fixing the blade tenon. Insert the blade tenon into the tenon groove and clamp it in place. This can be done manually or pneumatically.
[0022] (3) Automatic clamping of blade tip. The blade is clamped by a double support cylinder. The clamping part is supported in two sections. The clamping and loosening of the two sections are controlled by PLC respectively, and the instructions are integrated into the CNC belt grinding program. The clamping and loosening can be controlled in the panel or program.
[0023] (4) Automatic polishing of the blade body and inlet / outlet edges. A floating belt grinding system is used to polish the blade body and inlet / outlet edges. The type of belt can be selected based on the degree of blade damage. If the blade damage is categorized into three types from most severe to least severe: severe, mild, and minor, different processing methods can be used: For minor damage, the blade body can be directly polished with a nylon belt; for severe damage, a piled abrasive belt can be used for rough polishing, followed by a nylon belt for fine polishing; for minor damage, a floating nylon wheel grinding head can be used to polish the blade body. All three methods can ensure a surface roughness of Ra0.4µm after polishing. For the inlet / outlet edges, if the damage is severe, a floating polishing system with a nylon wheel is used; if the damage is minor, a nylon belt is used for direct polishing. When polishing the blade body area near the blade tip, a variable support fixture is used. When there is interference between the grinding head and the fixture, the support position is automatically changed. Polishing control parameters include linear speed, feed rate, and polishing pressure.
[0024] (5) Automatic polishing of the transition area. The transition area is polished using a floating grinding head with a nylon wheel. This system has the following advantages over a floating belt grinding system: higher polishing efficiency for the blade body or transition area, especially better fit for the transition area; higher material removal rate than nylon belts, while achieving a surface roughness of Ra0.4µm after polishing. Polishing control parameters include linear speed, feed rate, and polishing pressure. When polishing areas other than the blade tip, both supports at the blade tip are firmly engaged.
[0025] Using the aforementioned support fixtures and polishing methods, it is possible to automatically polish and repair all areas of large-sized fan blades with different degrees of damage using a single device and in a single setup.
[0026] The following example illustrates the variable support fixture and automatic polishing method for a certain type of aero-engine fan rotor blade (see...). Figure 1-3 ):
[0027] The fan blades of a certain type of aircraft engine have a height ≥600mm. Surface damage must be eliminated, and the surface roughness must reach Ra0.4um after polishing. Perform automatic polishing repair according to the following steps:
[0028] (1) Design the blade clamping system. The X / Y / Z / A / B / C axes of the CNC belt grinder are as follows: Figure 1 As shown, a tenon fixing fixture 7 and a blade tip support system are designed on the machine tool base 11. The blade tip support system includes a fixed tailstock 1, an upper cylinder 2 with a guide rod, and a lower cylinder 10. The fixed tailstock 1 contains a rotating shaft 12 coaxial with the machine tool's A-axis. The rotating shaft 12 is connected to a bearing system ( Figure 3 As shown, the upper cylinder 2 and lower cylinder 10 rotate synchronously with the A-axis during the polishing process. The upper cylinder 2 and lower cylinder 10 can be controlled to tighten and loosen respectively. The control commands are integrated into the machine tool program and panel. The top block 3 that contacts the blade is made of polytetrafluoroethylene to prevent damage to the blade.
[0029] (2) Fixing the blade tenon. Insert the blade 5 into the tenon fixing clamp 7. 9 is the positioning pin and 8 is the anti-misalignment pin to prevent the blade from being installed backwards. Finally, press the blade tightly.
[0030] (3) Automatic clamping of blade tip. The blade 5 is clamped by the clamping command of the upper cylinder 2 and the lower cylinder 10.
[0031] (4) Automatic polishing of blade body and inlet / outlet edges. Use four floating belt grinding heads for rough polishing of the blade body, using P280 hollow ball abrasive belts. The polishing parameters are: linear speed (10-15) m / s, feed rate (3000-5000) mm / min, and pressure (3-5) N. Then use nylon belts for fine polishing. The polishing parameters are: linear speed (6-8) m / s, feed rate (2000-3000) mm / min, and pressure (2-4) N. When polishing the blade tip area, the program segment adds the release and tightening of the guide cylinder. When the sanding belt floating grinding head 4 approaches the interference area of the upper cylinder 2 during the polishing process, the program segment releases the upper cylinder 2 in advance. At this time, the lower cylinder 10 remains in a tightened state. When polishing reaches the interference area of the lower cylinder 10 while moving away from the interference area of the upper cylinder 2, the pneumatic 2 is tightened, and then the lower cylinder 10 is released. Thus, the blade tip remains in a tightened state throughout the polishing process. The variable support method ensures the stability of the fixture support during the polishing process and leaves no polishing dead corners. When polishing other areas, both the upper cylinder 2 and the lower cylinder 10 are in a tightened state.
[0032] (5) Automatic polishing of the transition area. The damping table, blade root transition area, and inlet / outlet edge area are polished using a floating nylon wheel grinding head 6. The grinding head 6 can float along the Z-axis and achieve pressure control, with the nylon wheel driven by a motor. The nylon wheel uses a 200-mesh silicon carbide wheel and is equipped with a dresser. Before polishing, the nylon wheel is dressed to match the shape of the transition R, and the program is adjusted according to the size of the dressed polishing wheel. The polishing parameters are: linear velocity (6~10) m / s, feed rate (2000~3000) mm / min, and pressure (2~3) N.
[0033] The beneficial effects of this invention are:
[0034] (1) A variable support fixture system for fan blades was designed, which not only solves the problem of polishing chatter caused by the lack of support at the blade tip, but also ensures that no polishing dead corners are left during the support process. The repeatability of clamping near the blade tip is controlled within ±0.05mm. An automatic polishing method based on a floating sanding belt + floating nylon wheel dual grinding head system is provided, which can realize the automatic polishing, repair and elimination of faults of different damage levels in all areas of large-sized fan blades with one equipment and one clamping, thus achieving the goal of improving quality and efficiency.
[0035] (2) This invention solves the problem of automatic polishing and repair of large-sized fan blades with high bypass ratio, eliminating the need for manual polishing.
Claims
1. An automatic polishing method for high bypass ratio fan blades, characterized by: This process is implemented on a seven-axis CNC belt grinding machine. The seven axes include X / Y / Z / A / B / C and a normal pressure axis. The grinding machine is a dual-head system. One grinding head is a floating belt grinding system, with control parameters including linear velocity, feed rate, and polishing pressure, used to polish the blade body and inlet / outlet edges. The other grinding head is a floating nylon wheel system, with control parameters including linear velocity, feed rate, and polishing pressure, used to polish the damping table and blade root transition area. The process includes the following steps: 1) Design of blade clamping system: On the CNC belt sander base (11), a tenon fixing clamp (7) and a blade tip support system are designed. The blade tip support system includes a fixed tailstock (1), an upper cylinder (2) with a guide rod and a lower cylinder (10). The fixed tailstock (1) contains a rotating shaft (12) that is coaxial with the machine tool A axis. The rotating shaft (12) realizes the polishing process through the bearing system. The upper cylinder (2) and the lower cylinder (10) rotate synchronously with the A axis. The upper cylinder (2) and the lower cylinder (10) can be controlled to tighten and loosen respectively. The control commands are integrated in the machine tool program and panel. 2) Fixing the blade tenon: Insert the blade (5) into the tenon fixing clamp (7) and press the blade tightly; 3) Automatic blade tip clamping: The blade (5) is clamped by the clamping command of the upper cylinder (2) and the lower cylinder (10); 4) Automatic polishing of blade body and intake / exhaust edges: Use a floating belt grinding head (4) to rough polish the blade body; then use a nylon belt for fine polishing; when polishing the blade tip area, add the release and tightening of the guide cylinder in the program segment. When the floating belt grinding head (4) approaches the interference area of the upper cylinder (2) during the polishing process, the program segment releases the upper cylinder (2) in advance. At this time, the lower cylinder (10) remains in a tightened state. When polishing reaches the interference area of the lower cylinder (10) and moves away from the interference area of the upper cylinder (2), tighten the pneumatic (2) and then release the lower cylinder (10); when polishing other areas except the blade tip, both the upper cylinder (2) and the lower cylinder (10) are in a tightened state. 5) Automatic polishing of the transition area: The damping table, blade root transition area and air intake and exhaust side area are polished using a floating nylon wheel grinding head (6). The floating nylon wheel grinding head (6) can float along the Z-axis and achieve pressure control. The nylon wheel is driven to rotate by a motor. Before polishing, the nylon wheel is adjusted to match the shape of the transition R. The program is adjusted according to the size of the adjusted nylon wheel.
2. The automatic polishing method for high bypass ratio fan blades according to claim 1, characterized in that: The top block (3) that comes into contact with the blade is made of polytetrafluoroethylene.
3. The automatic polishing method for high bypass ratio fan blades according to claim 1, characterized in that: The tenon fixing clamp (7) is provided with a positioning pin (9) for positioning the blade tenon and an anti-misalignment pin (8) to prevent the blade from being installed backwards.
4. The automatic polishing method for high bypass ratio fan blades according to claim 1, characterized in that: In step 4), when using a floating abrasive belt grinding head (4) to rough polish the blade, a P280 hollow ball abrasive belt is used, and the polishing parameters are: linear speed of 10-15 m / s, feed rate of 3000-5000 mm / min, and pressure of 3-5 N; when using a nylon belt for fine polishing, the polishing parameters are: linear speed of 6-8 m / s, feed rate of 2000-3000 mm / min, and pressure of 2-4 N.
5. The automatic polishing method for high bypass ratio fan blades according to claim 1, characterized in that: In step 4), the blade body and inlet / outlet edges are automatically polished. The abrasive belt can be selected according to the degree of blade damage. If the blade body faults are divided into three types from major to minor—severe damage, minor damage, and slight damage—different process methods can be selected: For slight damage, the blade body can be polished directly with nylon abrasive belts; for severe damage, rough polishing can be done with stacked abrasive belts, followed by fine polishing with nylon belts; for slight damage, the blade body can be polished with floating nylon wheel grinding heads; for the inlet / outlet edges, if the damage is severe, a floating polishing system with nylon wheels is used; if the damage is slight, nylon abrasive belts are used for direct polishing; when polishing the blade body area near the blade tip, a blade tip support system is used, and the support position is automatically changed when there is interference between the grinding head and the fixture.
6. The automatic polishing method for high bypass ratio fan blades according to claim 1, characterized in that: In step 5), the floating nylon wheel grinding head (6) uses a silicon carbide wheel with a particle size of 200 mesh.
7. The automatic polishing method for high bypass ratio fan blades according to claim 1, characterized in that: In step 5), the polishing parameters are: linear velocity of 6-10 m / s, feed rate of 2000-3000 mm / min, and pressure of 2-3 N.
8. A variable support fixture for high bypass ratio fan blades, characterized in that: The system includes a tenon fixing fixture (7) and a blade tip support system. The blade tip support system includes a fixed tailstock (1), an upper cylinder (2) with a guide rod, and a lower cylinder (10). The fixed tailstock (1) contains a rotating shaft (12) that is coaxial with the machine tool A-axis. The rotating shaft (12) achieves the polishing process through a bearing system. The upper cylinder (2) and the lower cylinder (10) rotate synchronously with the A-axis. The upper cylinder (2) and the lower cylinder (10) can be controlled to tighten and loosen respectively. The control commands are integrated into the machine tool program and panel. The top block (3) that contacts the blade is made of polytetrafluoroethylene to prevent damage to the blade. The tenon fixing fixture (7) has a tenon groove for inserting the blade tenon, which can be clamped manually or pneumatically.
9. A variable support fixture for high bypass ratio fan blades according to claim 8, characterized in that: The top block (3) that comes into contact with the blade is made of polytetrafluoroethylene.
10. A variable support fixture for high bypass ratio fan blades according to claim 8, characterized in that: The tenon fixing clamp (7) is provided with a positioning pin (9) for positioning the blade tenon and an anti-misalignment pin (8) to prevent the blade from being installed backwards.