A stepped pressing jig for a thin-walled workpiece susceptible to deformation and a processing method

Abstract

This invention relates to the field of clamping fixture technology, specifically to a stepped clamping fixture and processing method for easily deformable thin-walled workpieces. The fixture includes a base body, with sliding frames slidably connected to both ends of the top of the base body. A clamping assembly is provided inside the sliding frame, and a fitting assembly is provided at the top of the sliding frame. Limiting rods are rotatably connected to both sides of the sliding frame, and locking components are provided on the limiting rods extending into the interior of the sliding frame. An adjusting assembly is provided inside the base body, and multiple sets of adsorption components are provided in the middle of the base body. Compared with existing clamping fixtures, this invention solves five major industry pain points: easy deformation and springback during clamping of easily deformable thin-walled workpieces, easy vibration and scrapping during cutting, poor positioning accuracy, weak versatility, and low clamping efficiency. It achieves stable clamping under low stress, significantly improving processing accuracy, product qualification rate, and production efficiency.

Description

Technical Field

[0001] This invention relates to the field of clamping fixture technology, specifically to a stepped clamping fixture and processing method for easily deformable thin-walled workpieces. Background Technology

[0002] With the rapid development of the semiconductor industry, including third-generation semiconductors, advanced packaging, MEMS devices, and high-power modules, easily deformable thin-walled components have been widely used throughout the entire semiconductor manufacturing and packaging process due to their lightweight, high integration, high heat dissipation, and miniaturization characteristics. From small silicon-based thin-walled sensing structures for MEMS devices, ultra-thin lead frames for IC packaging, and precision ceramic substrates for chip mounting, to large ultra-thin wafers after thinning 12-inch silicon wafers, precision thin-walled cavities in semiconductor lithography equipment, oxygen-free copper heat sinks for power semiconductor modules, and large-size IC carriers for advanced packaging, all are typical easily deformable thin-walled structures in the semiconductor industry. These types of workpieces generally have a wall thickness of ≤1mm, and some ultra-thin wafers and high-precision lead frames have wall thicknesses as low as 50μm. They have inherent characteristics such as extremely poor rigidity, weak resistance to deformation, low processing stability, and stringent requirements for surface cleanliness and non-destructive testing. The core contradiction in clamping and processing lies in ensuring stable clamping to avoid workpiece slippage and vibration during processes such as thinning, cutting, etching, electroplating, and bonding, while also controlling clamping stress to the extreme to prevent nanoscale elastic deformation and springback of the workpiece. At the same time, it is strictly forbidden to cause scratches, particulate contamination, and material damage to the functional surfaces of the workpiece during clamping. This places much higher precision and reliability requirements on the matching clamping fixtures than traditional machining.

[0003] Currently, the industry commonly uses the following types of fixtures for clamping and machining easily deformable thin-walled workpieces, but all of them have unavoidable technical defects: First, traditional radial clamping fixtures such as three-jaw chucks and vises are used. These fixtures rely on radial clamping force to fix the workpiece, and the clamping force acts directly on the fragile sidewalls of the thin-walled workpiece, which can easily cause elastic deformation of the workpiece. After machining, the workpiece springs back after being released, resulting in out-of-tolerance dimensional and positional tolerances such as roundness, cylindricity, and wall thickness uniformity. Even if soft jaws are used to optimize the contact area, the deformation risk caused by radial clamping force cannot be eliminated at the root, and they can only be used for regular circular workpieces, with extremely poor adaptability to irregularly shaped thin-walled parts. Second, single-stage pressure plate end face clamping fixtures are used. These types of fixtures abandon radial clamping and only use a single set of pressure plates to press the workpiece end face. Although this avoids the risk of radial deformation, it still has core defects: First, traditional pressure plates are single-stage, single-point pressing structures with highly concentrated clamping force, which can easily crush the workpiece's process bosses and cause local warping and unsupported positioning surfaces, making it impossible to ensure uniform force distribution around the entire circumference. Second, for thin-walled workpieces with multi-step structures, a single-stage pressure plate can only press the highest-end surface, while the lower steps lack effective clamping and support. During processing, thin-walled areas are prone to cutting vibration, resulting in problems such as chatter marks, tool deflection, and uneven wall thickness, and even workpiece cracking and scrapping. The product qualification rate can only be maintained at 40%-60%. Third, auxiliary filling type anti-deformation fixtures are used. In some industry scenarios, adhesive bonding, low-melting-point alloy filling, and paraffin filling are used to improve the processing rigidity of thin-walled workpieces. However, such solutions have extremely complicated processes, the filling and removal processes are time-consuming, the production efficiency is extremely low, and the filling materials are prone to causing surface contamination of the workpiece. Some low-melting-point alloys also pose environmental risks, making them completely unsuitable for the needs of large-scale, automated production. Fourth, the existing limited number of graded clamping fixtures still have significant shortcomings: most only have a single graded clamping function and do not integrate pre-positioning, flexible limiting, anti-loosening locking structures, etc., making the workpiece prone to slippage during clamping and resulting in poor repeatability; they cannot achieve precise graded control of clamping force, cannot match the clamping force requirements of different working conditions in roughing and finishing, and are difficult to balance clamping stability and anti-deformation requirements; at the same time, their structural versatility is weak, only adaptable to a single specification of workpiece, and workpiece change requires a complete fixture replacement, resulting in high changeover costs and long debugging cycles, which cannot meet the flexible production needs of multiple varieties and small batches. Therefore, it is particularly important to improve the existing clamping fixtures and design a new stepped clamping fixture and processing method for easily deformable thin-walled workpieces to solve the above-mentioned technical defects and improve the overall practicality of the clamping fixture. Summary of the Invention

[0004] The purpose of this invention is to provide a stepped clamping fixture and processing method for easily deformable thin-walled workpieces, solving five core technical defects of existing clamping fixtures. First, by adopting a flexible radial limiting and stepped axial clamping scheme, the irreversible deformation of traditional radial clamping is completely avoided, and the graded control of clamping force eliminates stress concentration and excessive springback after loosening. Second, by using vacuum pre-positioning, full-constraint clamping, and a multi-level buffer structure, the workpiece machining rigidity is significantly improved, solving the problems of vibration marks, tool deflection, and high scrap rate caused by cutting vibration. Third, by using dual synchronous centering transmission and a self-locking structure, the problems of clamping misalignment, easy workpiece slippage, and poor repeatability are solved. Fourth, by adopting a modular adjustable design, the pain points of weak versatility and high changeover costs of traditional fixtures are solved. Fifth, the fully integrated design simplifies the clamping process, solving the problems of low clamping efficiency and high operational safety risks for thin-walled parts.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A stepped clamping fixture for easily deformable thin-walled workpieces includes a base body, with movable frames slidably connected to both ends of the top of the base body. A clamping component is provided on the inner side of the movable frame, and a fitting component is provided at the top inside the movable frame. Limiting rods are rotatably connected to both sides of the movable frame, and locking components are provided on the limiting rods extending into the interior of the movable frame. An adjustment component is provided inside the base body, and multiple sets of adsorption components are provided in the middle of the interior of the base body.

[0007] The clamping assembly is used to flexibly clamp the workpiece. The clamping assembly includes a connecting rod fixedly connected inside the movable frame, a clamping rod on the outside of the connecting rod, and multiple sets of elastic clamping blocks fixedly connected to the outside of the clamping rod.

[0008] The bonding component is used to perform stepped positioning of the workpiece. The bonding component includes a movable frame that is slidably connected to the top of the inside of the movable frame. The bottom of the movable frame is provided with a bonding rod. A flexible connecting sleeve is fixedly connected to the bottom of the bonding rod. An elastic block is fixedly connected to the bottom of the flexible connecting sleeve.

[0009] The adjustment component is used to adjust the position of the two sets of moving frames. The adjustment component includes a drive block rotatably connected to the bottom of the base body. Both ends of the drive block are rotatably connected to drive rods.

[0010] The locking assembly is used to lock the limiting rod. The locking assembly includes a ratchet rotatably connected to one side of the inside of the moving frame, and a locking block is provided on the outside of the ratchet.

[0011] The adsorption assembly is used to limit the position of the workpiece. The adsorption assembly includes a connecting cylinder fixedly connected to the middle of the base body, and a suction cup is fixedly connected to the top of the connecting cylinder.

[0012] As a preferred embodiment of the present invention, the clamping rod is rotatably connected to two sets of first rotating rods at one end near the connecting rod, and a first sliding block is rotatably connected to the outer side of the first rotating rod, and the first sliding block is slidably connected to the connecting rod.

[0013] As a preferred embodiment of the present invention, the clamping rod is connected to the connecting rod by two sets of first damping springs, and a first compression spring is sleeved on both sides of the connecting rod and outside the two sets of first sliding blocks.

[0014] As a preferred embodiment of the present invention, a second compression spring is fixedly connected inside the elastic block, and multiple sets of the elastic blocks are arranged from high to low on the outside of the fitting rod. Two sets of second rotating rods are rotatably connected to the top of the fitting rod, and a second sliding block is rotatably connected to the top of the second rotating rod.

[0015] As a preferred embodiment of the present invention, the second sliding block is slidably connected to the movable frame, and a third compression spring is sleeved on both sides of the movable frame and on the outside of the two sets of second sliding blocks. The fitting rod is connected to the movable frame through two sets of second damping springs.

[0016] As a preferred embodiment of the present invention, a first driving screw is rotatably connected inside the movable frame and inside the movable bracket. The movable bracket is threadedly connected to the first driving screw. A first worm gear is fixedly connected to the top of the first driving screw. A first worm is meshed with the outer side of the first worm gear. A transmission rod is fixedly connected to the top of the movable bracket.

[0017] In a preferred embodiment of the present invention, the drive rod is rotatably connected to the movable frame, a drive gear is fixedly connected to the top of the drive block, drive racks are meshed on both sides of the drive gear, the drive racks are fixedly connected to the movable frame, the drive racks are slidably connected to the base body, a second worm gear is fixedly connected to the bottom of the drive block, a second worm is meshed on the outer side of the second worm gear, and the drive end of the first drive motor is fixedly connected to the outer side of the second worm.

[0018] As a preferred embodiment of the present invention, the locking block is rotatably connected to the moving frame, a fourth compression spring is fixedly connected to the outer side of the locking block, the fourth compression spring is fixedly connected to the moving frame, and a lever is fixedly connected to the outer side of the locking block extending to the moving frame.

[0019] In a preferred embodiment of the present invention, a piston is slidably connected inside the connecting cylinder, and a second drive screw is rotatably connected inside the connecting cylinder and located inside the piston. A synchronous pulley is fixedly connected to the bottom of the second drive screw, and two sets of synchronous pulleys are connected by a synchronous belt. A second drive motor is fixedly connected inside the base body and located at the bottom of one set of synchronous pulleys. The drive end of the second drive motor is fixedly connected to one set of synchronous pulleys. An air inlet and an air outlet are respectively opened at the top of the connecting cylinder. A closing plate is rotatably connected to the outside of both the air inlet and the air outlet. The closing plate is connected to the connecting cylinder by a torsion spring. The connecting cylinder is interconnected with the suction cup through the air inlet and the air outlet.

[0020] The method of using the stepped clamping fixture for easily deformable thin-walled workpieces of the present invention includes:

[0021] S1: Fixture initialization and workpiece vacuum pre-positioning: Place the workpiece at the center of the top surface of the base body, start the adsorption assembly, and drive the piston downward through the second drive motor to create negative pressure in the connecting cylinder, so that the suction cup completes the vacuum adsorption positioning of the bottom surface of the workpiece.

[0022] S2: Bidirectional synchronous flexible clamping limit: The first drive motor of the adjustment component is started, and the two sets of moving frames are synchronously driven to feed towards each other through the drive block, drive gear, drive rack and drive rod. The workpiece sidewall is flexibly limited by the elastic clamping block, the first damping spring and the first compression spring of the clamping component.

[0023] S3: Stepped adaptive clamping and auxiliary locking: Rotating the transmission rod drives the moving frame downward through the first worm, the first worm wheel, and the first drive screw, so that the elastic block, flexible connecting sleeve, and second compression spring of the fitting component achieve stepped adaptive clamping on the top surface of the workpiece; rotating the limit rod completes the limit locking by the ratchet, locking block, and fourth compression spring of the locking component;

[0024] S4: Staged cutting and status monitoring: Switch clamping force according to roughing and finishing, start machine tool processing; monitor the vacuum degree of chuck and clamping status throughout the process, and use micro-lubrication and cooling to ensure processing accuracy and prevent workpiece deformation;

[0025] S5: Staged clamping, workpiece removal, and fixture reset: After processing, allow the machine to stand still to release pressure. Then, in the order of unlocking the limit rod, lifting the bonding component, retracting the moving frame, and releasing the suction cup, staged clamping is performed to smoothly remove the workpiece. Clean the machine and reset all components.

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] 1. In this invention, through the design of the clamping assembly, the traditional rigid clamping is transformed into adaptive flexible clamping through the linkage buffer structure of the connecting rod, clamping rod, first rotating rod, first sliding block, first damping spring and first compression spring. The clamping force can be adaptively adjusted according to the shape of the workpiece, and there is no rigid extrusion throughout the process, which eliminates the elliptical and drum-shaped deformation and surface damage of thin-walled workpieces during clamping from the root.

[0028] Multiple sets of elastic clamping blocks adopt a surface contact design, which evenly distributes the clamping force on the side wall of the workpiece, avoiding stress concentration at a single point. At the same time, only radial limiting force is applied to the workpiece, without generating excessive clamping force, which ensures that the workpiece does not slip during processing and does not affect the dimensional accuracy of the thin-walled area at all.

[0029] The structure is fed synchronously with the moving frame, requiring no separate debugging, resulting in high clamping efficiency. It can adapt to easily deformable thin-walled workpieces with different wall thicknesses and dimensions, and has strong versatility.

[0030] 2. In this invention, through the design of the bonding component, multiple sets of elastic blocks are arranged in a stepped manner from high to low, which can simultaneously bond to the stepped end faces of different heights on the top surface of the workpiece, realize the simultaneous pressing of multiple end faces in one operation, transform the traditional single-point pressing into multi-point surface contact uniform pressing, and the pressing force is evenly distributed throughout the circumference, completely eliminating stress concentration and workpiece warping deformation.

[0031] Through a multi-stage buffer structure consisting of a flexible connecting sleeve, a second compression spring, a second rotating rod, a second sliding block, a third compression spring, and a second damping spring, adaptive constant force clamping is achieved. The clamping force can be flexibly adjusted according to the requirements of roughing and finishing: during roughing, sufficient clamping force is ensured to prevent movement and resist cutting vibration; during finishing, low-stress clamping is used to avoid elastic deformation, thus solving the core pain point of excessive springback after loosening of thin-walled parts.

[0032] The linkage structure ensures that the bonding rod remains horizontal during its downward movement, and all clamping points are subjected to uniform force, without bias or suspension. This significantly improves the system rigidity during the machining of thin-walled workpieces, effectively suppresses cutting vibration marks, and enhances surface finish and dimensional accuracy.

[0033] 3. In this invention, the locking component is designed with a one-way self-locking structure of ratchet and locking block, combined with the automatic reset design of the fourth compression spring, which can realize the quick locking and one-key unlocking of the limit rod rotation angle. The operation is convenient, and the locking state will not loosen due to machine tool cutting vibration. The stability of the auxiliary limit is guaranteed throughout the process, and the axial movement of the workpiece is further restricted during processing.

[0034] The purely mechanical self-locking structure has no additional electrical components, resulting in high reliability, low failure rate, suitability for complex machine tool processing conditions, and long service life.

[0035] The limiting angle of the limiting rod can be flexibly adjusted according to the workpiece size, adapting to thin-walled workpieces of different specifications. It has strong versatility and forms a double limiting with the stepped clamping structure of the fitting component, further improving the safety and stability of the fixture clamping.

[0036] 4. In this invention, by designing the adjustment components, a dual synchronous transmission structure of drive gear, drive rack and drive rod is adopted. A single first drive motor can drive two sets of moving frames to achieve bidirectional synchronous feeding in opposite directions, ensuring that the displacement of the moving frames on both sides is completely consistent. The workpiece is always in the center position of the fixture, without skew or unilateral force, thus avoiding the machining dimension deviation caused by workpiece clamping misalignment from the root.

[0037] The transmission structure of the second worm gear and the second worm has a self-locking characteristic. After the feed is in place, the position of the moving frame can be automatically locked, and it will not be displaced due to cutting force, resulting in strong clamping stability.

[0038] With a wide adjustment range, it can quickly adapt to easily deformable thin-walled workpieces of different widths and shapes without the need to change the main body of the fixture. It has strong versatility, greatly shortens the debugging time for workpiece changeover, and improves production efficiency.

[0039] 5. In this invention, through the design of the adsorption component, the bottom surface of the workpiece is pre-positioned without stress by vacuum adsorption. No additional deformation of the workpiece will occur during the clamping process. The workpiece reference surface can be quickly and completely attached to the fixture reference surface, eliminating the initial warping and suspension of the workpiece, providing a precise reference for subsequent clamping and pressing, and ensuring that the repeated clamping positioning accuracy is ≤ ±0.005mm.

[0040] It adopts a piston-type negative pressure generating structure, and drives multiple adsorption components synchronously through a second drive motor, synchronous wheel and synchronous belt. The negative pressure is stable and uniform, the adsorption force is controllable, the response speed is fast, and it will not damage the bottom surface and surface coating of the workpiece.

[0041] The one-way closed plate design of the air inlet and outlet ensures that the suction cup can still maintain negative pressure in the power outage and shutdown state, preventing the workpiece from accidentally slipping and ensuring high safety; together with the clamping component and the bonding component, it forms a fully constrained composite clamping system, which greatly improves the reliability and processing accuracy of thin-walled workpiece clamping. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0043] Figure 2 This is a schematic diagram of the main structure of the base of the present invention;

[0044] Figure 3 This is a schematic diagram of the adjustment component structure of the present invention;

[0045] Figure 4This is a schematic diagram of the movable frame structure of the present invention;

[0046] Figure 5 This is a schematic diagram of the moving frame portion of the present invention;

[0047] Figure 6 This is a schematic diagram of the clamping component structure of the present invention;

[0048] Figure 7 This is a schematic diagram of the bonding component structure of the present invention;

[0049] Figure 8 This is a schematic diagram of the flexible connecting sleeve structure of the present invention;

[0050] Figure 9 This is a schematic diagram of the limiting rod structure of the present invention;

[0051] Figure 10 This is a schematic diagram of the locking component structure of the present invention;

[0052] Figure 11 This is a schematic diagram of the adsorption component structure of the present invention;

[0053] Figure 12 This is a schematic diagram of the workpiece structure of the present invention. Figure 1 ;

[0054] Figure 13 This is a schematic diagram of the workpiece structure of the present invention. Figure 2 ;

[0055] Figure 14 This is a schematic diagram of the workpiece structure of the present invention. Figure 3 .

[0056] In the diagram: 1. Base body; 2. Moving frame; 3. Clamping assembly; 4. Fitting assembly; 5. Limiting rod; 6. Locking assembly; 7. Adjusting assembly; 8. Adsorption assembly; 9. Connecting rod; 10. Clamping rod; 11. Elastic clamping block; 12. Moving frame; 13. Fitting rod; 14. Flexible connecting sleeve; 15. Elastic block; 16. Driving block; 17. Driving rod; 18. Ratchet; 19. Locking block; 20. Connecting cylinder; 21. Suction cup; 22. First rotating rod; 23. First sliding block; 24. First damping spring; 25. First compression spring; 26. Second compression spring. 27. Second rotating rod; 28. Second sliding block; 29. ​​Third compression spring; 30. Second damping spring; 31. First drive screw; 32. First worm gear; 33. First worm; 34. Drive gear; 35. Drive rack; 36. Second worm gear; 37. Second worm; 38. First drive motor; 39. Fourth compression spring; 40. Paddle lever; 41. Piston; 42. Second drive screw; 43. Synchronous pulley; 44. Synchronous belt; 45. Second drive motor; 46. Air inlet; 47. Air outlet; 48. Closing plate; 49. Transmission rod. Detailed Implementation

[0057] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0058] Example:

[0059] Please see Figures 1-14 The present invention provides a technical solution:

[0060] A stepped clamping fixture for easily deformable thin-walled workpieces includes a base body 1, with movable frames 2 slidably connected to both ends of the top of the base body 1, a clamping component 3 provided on the inner side of the movable frame 2, a fitting component 4 provided at the top inside the movable frame 2, and limit rods 5 rotatably connected to both sides of the movable frame 2. The limit rods 5 extend into the interior of the movable frame 2 and are provided with locking components 6. An adjustment component 7 is provided inside the base body 1, and multiple sets of adsorption components 8 are provided in the middle of the interior of the base body 1.

[0061] The clamping assembly 3 is used to perform flexible clamping of the workpiece. The clamping assembly 3 includes a connecting rod 9 fixedly connected inside the movable frame 2, a clamping rod 10 is provided on the outside of the connecting rod 9, and multiple sets of elastic clamping blocks 11 are fixedly connected to the outside of the clamping rod 10.

[0062] The bonding component 4 is used to perform stepped limiting treatment on the workpiece. The bonding component 4 includes a movable frame 12 that is slidably connected to the top of the inside of the movable frame 2. The bottom of the movable frame 12 is provided with a bonding rod 13. A flexible connecting sleeve 14 is fixedly connected to the bottom of the bonding rod 13. An elastic block 15 is fixedly connected to the bottom of the flexible connecting sleeve 14.

[0063] The adjustment component 7 is used to adjust the position of the two sets of moving frames 2. The adjustment component 7 includes a drive block 16 rotatably connected to the bottom of the base body 1. Both ends of the drive block 16 are rotatably connected to drive rods 17.

[0064] The locking component 6 is used to lock the limit rod 5. The locking component 6 includes a ratchet 18 rotatably connected to one side of the inside of the movable frame 2, and a locking block 19 is provided on the outside of the ratchet 18.

[0065] The adsorption component 8 is used to limit the position of the workpiece. The adsorption component 8 includes a connecting cylinder 20 fixedly connected to the middle of the base body 1. A suction cup 21 is fixedly connected to the top of the connecting cylinder 20.

[0066] Furthermore, two sets of first rotating rods 22 are rotatably connected to one end of the clamping rod 10 near the connecting rod 9. A first sliding block 23 is rotatably connected to the outer side of the first rotating rod 22. The first sliding block 23 is slidably connected to the connecting rod 9. The clamping rod 10 is connected to the connecting rod 9 through two sets of first damping springs 24. A first compression spring 25 is sleeved on both sides of the connecting rod 9 and on the outer side of the two sets of first sliding blocks 23. When the clamping rod 10 contacts the workpiece, the first compression spring 25 drives the first sliding block 23 to move, causing the first rotating rod 22 to move, which in turn drives the clamping rod 10 to move, so that the clamping rod 10 fits against the surface of the workpiece. With the help of the two sets of first damping springs 24 and multiple sets of elastic clamping blocks 11, the workpiece can be flexibly clamped.

[0067] The elastic block 15 is internally fixedly connected to a second compression spring 26. Multiple sets of elastic blocks 15 are arranged from high to low on the outer side of the fitting rod 13. Two sets of second rotating rods 27 are rotatably connected to the top of the fitting rod 13. A second sliding block 28 is rotatably connected to the top of the second rotating rod 27. The second sliding block 28 is slidably connected to the moving frame 12. A third compression spring 29 is sleeved on both sides of the moving frame 12 and on the outer side of the two sets of second sliding blocks 28. The fitting rod 13 is connected to the moving frame 12 by two sets of second damping springs 30. The frame 12 is connected, and the second sliding block 28 is displaced by the third compression spring 29, which causes the second rotating rod 27 to move and the bonding rod 13 to move downward. With the help of the second damping spring 30, the bonding rod 13 can fit against the top of the workpiece. When the bonding rod 13 contacts the workpiece, multiple sets of elastic blocks 15 contact the top of the workpiece. The multiple sets of elastic blocks 15 are arranged from high to low and cooperate with the second compression spring 26 inside the flexible connecting sleeve 14 to fit against the top of the workpiece and perform stepped pressing on the workpiece.

[0068] Secondly, a first drive screw 31 is rotatably connected inside the movable frame 2 and inside the movable frame 12. The movable frame 12 is threadedly connected to the first drive screw 31. A first worm gear 32 is fixedly connected to the top of the first drive screw 31. A first worm 33 is meshed with the outer side of the first worm gear 32. A transmission rod 49 is fixedly connected to the top of the movable frame 12 by extending the first worm 33. Rotating the transmission rod 49 drives the first worm 33 to rotate, causing the first worm gear 32 to rotate, thereby enabling the first drive screw 31 to rotate and drive the movable frame 12 to move.

[0069] Furthermore, the drive rod 17 is rotatably connected to the moving frame 2. The top of the drive block 16 is fixedly connected to the drive gear 34, and both sides of the drive gear 34 are meshed with drive racks 35. The drive racks 35 are fixedly connected to the moving frame 2 and slidably connected to the base body 1. The bottom of the drive block 16 is fixedly connected to the second worm gear 36, and the outer side of the second worm gear 36 is meshed with the second worm 37. The outer side of the second worm 37 is fixedly connected to the drive end of the first drive motor 38. When the first drive motor 38 is started, it drives the second worm 37 to rotate, causing the second worm gear 36 to rotate, which in turn drives the drive block 16 to rotate. This allows the two sets of drive rods 17 to move, which in turn moves the moving frame 2. At the same time, when the drive block 16 rotates, it synchronously drives the drive gear 34 to rotate, causing the two sets of drive racks 35 to move, which in turn moves the moving frame 2. This allows the two sets of moving frames 2 to move stably.

[0070] Furthermore, the locking block 19 is rotatably connected to the moving frame 2. A fourth compression spring 39 is fixedly connected to the outer side of the locking block 19. The fourth compression spring 39 is fixedly connected to the moving frame 2. The locking block 19 extends to the outer side of the moving frame 2 and is fixedly connected to a lever 40. Moving the lever 40 causes the locking block 19 to rotate, displacing it from the outer side of the ratchet 18, allowing the ratchet 18 to rotate. This allows the limiting rod 5 to rotate, bringing the limiting rod 5 into contact with the surface of the workpiece. Releasing the lever 40 causes the locking block 19 to reset via the fourth compression spring 39, bringing the locking block 19 into contact with the ratchet 18 and locking the ratchet 18, thereby locking the limiting rod 5.

[0071] Furthermore, a piston 41 is slidably connected inside the connecting cylinder 20. A second drive screw 42 is rotatably connected inside the connecting cylinder 20 and located inside the piston 41. A synchronous pulley 43 is fixedly connected to the bottom of the second drive screw 42. Two sets of synchronous pulleys 43 are connected by a synchronous belt 44. A second drive motor 45 is fixedly connected inside the base body 1 and located at the bottom of one set of synchronous pulleys 43. The drive end of the second drive motor 45 is fixedly connected to one set of synchronous pulleys 43. An air inlet 46 and an air outlet 47 are respectively opened at the top of the connecting cylinder 20. A closing plate 48 is rotatably connected to the outside of both the air inlet 46 and the air outlet 47. The closing plate 48 is connected to the connecting cylinder 20 by a torsion spring. The air inlet 46 and outlet 47 are connected to the suction cup 21. When the workpiece is placed on the top of the base body 1, it contacts the suction cup 21. The second drive motor 45 is started to drive a set of synchronous pulleys 43 to rotate. The synchronous belt 44 drives another set of synchronous pulleys 43 to rotate, thereby enabling the two sets of second drive screws 42 to rotate. This drives the piston 41 to move downward from the top of the connecting cylinder 20, creating a negative pressure inside the connecting cylinder 20. The closing plate 48 at the bottom of the air inlet 46 is affected by the negative pressure and opens the air inlet 46, introducing the gas inside the suction cup 21 into the connecting cylinder 20. This limits the workpiece to the top of the suction cup 21, thus limiting the workpiece.

[0072] In this embodiment, the specific implementation scenario is as follows: During actual use, it is confirmed that there is no jamming in any moving parts of the fixture, no wear or aging in the elastic clamping block 11 of the clamping component 3, the flexible connecting sleeve 14 and elastic block 15 of the fitting component 4, no scratches or metal debris on the surface of the suction cup 21 of the adsorption component 8, and that all spring components reset normally; using special tools, such as an air gun, lint-free cloth, precision cleaning agent, cork squeegee or plastic scraper, the top surface of the base body 1, the working surface of the suction cup 21, and the clamping and pressing contact surfaces are cleaned to avoid hard impurities causing workpiece damage or exceeding the tolerance of the positioning surface fitting gap; the equipment control system is started, triggering the corresponding actuator to complete the full-dimensional reset, and the first drive motor 38 is started to rotate in reverse, driving the two sets of moving frames 2 to slide in reverse along the top surface of the base body 1 through the adjustment component 7, returning to the starting position. When the maximum spacing is reached, the transmission rod 49 is rotated in the reverse direction, which drives the first drive screw 31 to rotate in the reverse direction, driving the moving frame 12 to rise to the initial position at the top of the moving frame 2. The lever 40 is moved to completely separate the locking block 19 of the locking component 6 from the ratchet 18. The limit rod 5 is rotated to the initial position where it is in contact with the side wall of the moving frame 2. The lever 40 is released to complete the reset. The second drive motor 45 is started to run in the reverse direction, driving the piston 41 to rise to the initial position at the top of the connecting cylinder 20. The suction cup 21 returns to normal pressure with no negative pressure residue. According to the shape, wall thickness and material of the thin-walled workpiece to be processed, the target clamping spacing of the two sets of moving frames 2, the downward stroke of the stepped pressing, the safety negative pressure value of the adsorption component 8 and the maximum buffer stroke of clamping and pressing are preset in advance to prevent over-travel operation from causing workpiece deformation.

[0073] The thin-walled workpiece to be processed is placed stably at the center of the top surface of the base body 1, so that the bottom reference surface of the workpiece is completely in contact with the top surface of the base, the center of the workpiece is aligned with the center of the suction cup 21 of the adsorption component 8, and the two sides of the workpiece to be clamped correspond to the positions of the clamping components 3 of the two sets of moving frames 2, without lateral deviation. The second drive motor 45 is started to run in the forward direction, driving the two sets of second drive screws 42 to rotate synchronously through the synchronous pulley 43 and the synchronous belt 44. The drive piston 41 slides smoothly downward along the inner wall of the connecting cylinder 20, so that a stable negative pressure is formed inside the connecting cylinder 20; under the action of negative pressure, air is introduced. The closing plate 48 at the port 46 automatically opens against the torsion spring force, and the air in the suction cup 21 is quickly drawn into the connecting cylinder 20. Meanwhile, the closing plate 48 at the air outlet 47 is kept closed by negative pressure and torsion spring force, so that a continuous vacuum adsorption force is formed between the suction cup 21 and the bottom surface of the workpiece, which firmly limits the workpiece to the base reference surface. The vacuum degree in the suction cup 21 is detected in real time by the negative pressure sensor to confirm that the preset value has been reached and there is no pressure drop. The fit gap between the bottom surface of the workpiece and the reference surface is checked with a feeler gauge to ensure that the gap is ≤0.005mm, without warping or suspension, thus completing the reference pre-positioning of the workpiece.

[0074] The first drive motor 38 is started and rotates in the forward direction, driving the second worm gear 37 to rotate. Through meshing transmission, the second worm wheel 36 and the drive block 16 rotate synchronously. When the drive block 16 rotates, it forms a double synchronous drive: on the one hand, the two sets of moving frames 2 slide synchronously towards each other through the drive rods 17 at both ends; on the other hand, through the meshing transmission of the drive gear 34 and the drive racks 35 on both sides, the two sets of moving frames 2 are synchronously driven to feed smoothly. The double transmission ensures that the displacement of the moving frames 2 on both sides is completely synchronized, avoiding the workpiece being biased by force on one side. When the moving frame 2 is fed to the point where the clamping assembly 3 contacts the side wall of the workpiece, the multiple sets of elastic clamping blocks 11 on the outside of the clamping rod 10 first make flexible contact with the side wall of the workpiece. The contact reaction force triggers the clamping rod 10 to move smoothly towards the connecting rod 9; clamping When rod 10 is displaced, it drives the two sets of first rotating rods 22 to deflect synchronously, pushing the first sliding blocks 23 on both sides to slide in the opposite direction along the connecting rod 9, compressing the first compression spring 25, and stretching the first damping spring 24 at the same time; through the buffering and energy absorption of the first compression spring 25 and the first damping spring 24, the traditional rigid clamping is transformed into surface contact flexible clamping, and the clamping force is evenly distributed on multiple sets of elastic clamping blocks 11, completely avoiding single-point stress concentration that crushes thin-walled workpieces. When the moving frame 2 is fed to the preset clamping position, the first drive motor 38 is immediately stopped. At this time, the clamping assembly 3 only applies radial limiting force to the workpiece, without excessive clamping force; at the same time, through the brake function of the drive motor, the position of the moving frame 2 is locked to ensure that the clamping state is stable throughout the process and there is no displacement deviation.

[0075] Rotating the clamping drive rod 17 at the top of the moving frame 2 drives the first worm gear 33 to rotate, which in turn drives the first worm wheel 32 and the first drive screw 31 to rotate synchronously through meshing transmission. Through threaded transmission, the moving frame 12 is driven to slide smoothly downward along the inner wall of the moving frame 2, causing the bonding rod 13 and the stepped elastic block 15 to approach the top step surface of the workpiece at a uniform speed. When the moving frame 12 descends to the point where the elastic block 15 contacts the top surface of the workpiece, multiple sets of elastic blocks 15 arranged from high to low sequentially bond with the step end surfaces of different heights on the top surface of the workpiece. During the bonding process, the flexible connecting sleeve 14 adapts to the action of the elastic block 14. Deformation, in conjunction with the second compression spring 26 inside the elastic block 15, ensures that each set of elastic blocks 15 can fully fit against the corresponding step surface, eliminating fitting gaps; simultaneously, the fitting rod 13 is slightly displaced upward by the contact reaction force, causing the two sets of second rotating rods 27 to deflect, pushing the second sliding blocks 28 on both sides to slide in the opposite direction along the moving frame 12, compressing the third compression spring 29, and simultaneously stretching the second damping spring 30. Through the buffering effect of the springs, pre-fitting is achieved without hard pressure or interference, avoiding elastic deformation caused by local pressure on the workpiece. The clamping force is strictly controlled according to the roughing and finishing requirements, ensuring full... The process ensures that the pressure deviation at all clamping points is ≤10%. The transmission rod 49 is rotated further, causing the moving frame 12 to descend slightly. Through the elastic force of the third compression spring 29 and the second damping spring 30, the clamping force is gradually increased, with the single-group clamping force controlled at 30-50N. This ensures that the workpiece does not move or vibrate under the large cutting force of rough machining, while also avoiding stress concentration. After rough machining is completed, the transmission rod 49 is rotated slightly upwards in the opposite direction, reducing the clamping force to 30%-50% of that used in rough machining. This only maintains the stable positioning of the workpiece, completely eliminating elastic deformation of the workpiece caused by the clamping force, and ensuring the precision machining dimensions. To ensure dimensional accuracy and prevent excessive rebound after loosening, after adjusting the clamping force, the lever 40 is moved to separate the locking block 19 of the locking assembly 6 from the ratchet 18. The limiting rod 5 is rotated until its end is in contact with the non-machined area on the top surface of the workpiece, which only provides auxiliary limiting and does not apply additional clamping force. When the lever 40 is released, the fourth compression spring 39 drives the locking block 19 to reset and engage with the ratchet 18 to lock the rotation angle of the limiting rod 5, further limiting the axial movement of the workpiece during processing. Finally, a fully constrained low-stress clamping system with adsorption positioning, flexible clamping, stepped clamping and auxiliary limiting is formed.

[0076] Before the formal cutting, check the vacuum level of the chuck 21, the locking status of the moving frame 2, the clamping force value, and the gaps between the mating surfaces again. After confirming that there are no abnormalities, start the machine tool to execute the machining program. During the cutting process, monitor the negative pressure value of the chuck 21 and the vibration of each component of the fixture in real time. If the negative pressure drops or the clamping force fluctuates, stop the machining program immediately and readjust the clamping status to avoid machining deviations caused by workpiece slippage or deformation. Use micro-lubrication and cooling throughout the process to reduce workpiece thermal deformation caused by cutting heat and to prevent cutting fluid from entering the chuck 21 and affecting the adsorption stability. After the roughing is completed, stop the machine tool and adjust the stepped clamping force to the finishing gear according to the requirements of the fourth stage. After confirming that the clamping status is stable, execute the finishing program.

[0077] After finishing, stop the machine tool spindle and leave it in the fixture clamped state for 2-3 minutes to release the internal stress generated during workpiece cutting. This prevents stress rebound deformation caused by immediate loosening. Strictly follow the order completely opposite to the clamping sequence to loosen the clamp in stages, avoiding stress abrupt changes caused by unilateral or one-time loosening. Move the lever 40 to release the locking block 19 from the ratchet 18. Rotate the limit lever 5 back to the initial position to cancel the auxiliary limit. Rotate the transmission rod 49 in the reverse direction to drive the first drive screw 31 to rotate in the reverse direction, driving the moving frame 12 to move upward smoothly, gradually reducing the clamping force until all elastic blocks 15 are completely separated from the top surface of the workpiece, returning to the initial position. The first drive motor 38 is started to rotate in reverse, driving the two sets of moving frames 2 to slide in the opposite direction synchronously. The clamping component 3 moves backward synchronously with the moving frame 2, completely separating from the side wall of the workpiece. The flexible clamping limit is canceled. The second drive motor 45 is started to rotate in reverse, driving the piston 41 to move smoothly upward along the inner wall of the connecting cylinder 20. The pressure inside the connecting cylinder 20 returns to normal. The closing plate 48 at the air outlet 47 opens, and air enters the suction cup 21. The vacuum suction force is completely released, and the pre-positioning of the bottom surface of the workpiece is canceled. After the clamping is completed, the workpiece is removed smoothly to avoid bumping or scratching the machined surface. The cutting fluid and debris on the surface of the workpiece are cleaned with anhydrous ethanol, and then the workpiece is transferred to the three-coordinate dimension inspection process.

[0078] After removing the workpiece, thoroughly clean the contact surfaces of the base body 1, suction cup 21, clamping assembly 3, and bonding assembly 4, removing cutting fluid, metal shavings, and impurities. Reset all moving parts of the fixture to their initial positions, turn off the equipment control system and power supply, and check whether the elasticity of each elastic element has diminished, and whether the flexible contact parts are worn or have indentations. Replace them promptly if aging or damage is found. Regularly lubricate each threaded transmission pair and rotating pair to ensure smooth movement. Regularly check the vacuum holding capacity and clamping force control accuracy of the suction cup 21 to ensure stable repeat clamping accuracy of the fixture. Compared with existing clamping fixtures, this invention improves the overall practicality of the clamping fixture through its design.

[0079] The method of using the stepped clamping fixture for easily deformable thin-walled workpieces of the present invention includes:

[0080] Step 1: Fixture initialization and workpiece vacuum pre-positioning: Place the workpiece at the center of the top surface of the base body 1, start the adsorption assembly 8, and drive the piston 41 downward through the second drive motor 45 to create a negative pressure in the connecting cylinder 20, and complete the vacuum adsorption positioning of the bottom surface of the workpiece by the suction cup 21.

[0081] Step 2: Bidirectional synchronous flexible clamping and limiting: Start the first drive motor 38 of the adjustment component 7, and drive the two sets of moving frames 2 to feed towards each other synchronously through the drive block 16, drive gear 34, drive rack 35 and drive rod 17. The workpiece sidewall is flexibly limited by the elastic clamping block 11, the first damping spring 24 and the first compression spring 25 of the clamping component 3.

[0082] Step 3: Stepped adaptive clamping and auxiliary locking: Rotate the transmission rod 49, which drives the moving frame 12 downward through the first worm 33, the first worm wheel 32, and the first drive screw 31, so that the elastic block 15, the flexible connecting sleeve 14, and the second compression spring 26 of the contact component 4 achieve stepped adaptive clamping on the top surface of the workpiece; rotate the limit rod 5, and the ratchet 18, the locking block 19, and the fourth compression spring 39 of the locking component 6 complete the limit locking;

[0083] Step 4: Phased cutting and status monitoring: Switch the clamping force according to roughing and finishing, and start the machine tool for processing; monitor the vacuum degree and clamping status of the chuck 21 throughout the process, and use micro-lubrication and cooling to ensure machining accuracy and prevent workpiece deformation;

[0084] Step 5: Grading, workpiece removal and fixture reset: After processing, allow the workpiece to stand still to release pressure. Grading is performed in the following order: unlocking limit rod 5, lifting the bonding component 4, retracting the moving frame 2, and releasing the suction cup 21. The workpiece is then removed smoothly, cleaned, and each component is reset.

[0085] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art 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 appended claims and their equivalents.

Claims

1. A stepped clamping fixture for easily deformable thin-walled workpieces, comprising a base body (1), characterized in that: The base body (1) has two sliding frames (2) at its top ends. The inner side of the moving frame (2) is provided with a clamping component (3). The top of the moving frame (2) is provided with a fitting component (4). The two sides of the moving frame (2) are rotatably connected with a limiting rod (5). The limiting rod (5) extends into the interior of the moving frame (2) and is provided with a locking component (6). The interior of the base body (1) is provided with an adjustment component (7). The middle of the interior of the base body (1) is provided with multiple sets of adsorption components (8). The clamping assembly (3) is used to perform flexible clamping on the workpiece. The clamping assembly (3) includes a connecting rod (9) fixedly connected inside the movable frame (2). A clamping rod (10) is provided on the outside of the connecting rod (9). Multiple sets of elastic clamping blocks (11) are fixedly connected to the outside of the clamping rod (10). The bonding component (4) is used to perform stepped positioning of the workpiece. The bonding component (4) includes a movable frame (12) that is slidably connected to the top of the movable frame (2). The bottom of the movable frame (12) is provided with a bonding rod (13). The bottom of the bonding rod (13) is fixedly connected with a flexible connecting sleeve (14). The bottom of the flexible connecting sleeve (14) is fixedly connected with an elastic block (15). The adjustment component (7) is used to adjust the position of the two sets of moving frames (2). The adjustment component (7) includes a drive block (16) rotatably connected to the bottom of the base body (1). Both ends of the drive block (16) are rotatably connected to drive rods (17). The locking assembly (6) is used to lock the limiting rod (5). The locking assembly (6) includes a ratchet (18) rotatably connected to one side of the inside of the moving frame (2). A locking block (19) is provided on the outside of the ratchet (18). The adsorption component (8) is used to limit the position of the workpiece. The adsorption component (8) includes a connecting cylinder (20) fixedly connected to the middle of the base body (1). A suction cup (21) is fixedly connected to the top of the connecting cylinder (20).

2. A stepped clamping fixture for easily deformable thin-walled workpieces according to claim 1, characterized in that: Two sets of first rotating rods (22) are rotatably connected to one end of the clamping rod (10) near the connecting rod (9). A first sliding block (23) is rotatably connected to the outer side of the first rotating rod (22). The first sliding block (23) is slidably connected to the connecting rod (9).

3. A stepped clamping fixture for easily deformable thin-walled workpieces according to claim 2, characterized in that: The clamping rod (10) is connected to the connecting rod (9) by two sets of first damping springs (24). The connecting rod (9) is fitted with first compression springs (25) on both sides and outside the two sets of first sliding blocks (23).

4. A stepped clamping fixture for easily deformable thin-walled workpieces according to claim 1, characterized in that: The elastic block (15) is internally fixedly connected to a second compression spring (26). Multiple sets of elastic blocks (15) are arranged from high to low on the outside of the fitting rod (13). The top of the fitting rod (13) is rotatably connected to two sets of second rotating rods (27), and the top of the second rotating rods (27) is rotatably connected to a second sliding block (28).

5. A stepped clamping fixture for easily deformable thin-walled workpieces according to claim 4, characterized in that: The second sliding block (28) is slidably connected to the moving frame (12). The moving frame (12) is provided with a third compression spring (29) on both sides and outside the two sets of second sliding blocks (28). The fitting rod (13) is connected to the moving frame (12) through two sets of second damping springs (30).

6. A stepped clamping fixture for easily deformable thin-walled workpieces according to claim 1, characterized in that: The first drive screw (31) is rotatably connected inside the movable frame (2) and inside the movable frame (12). The movable frame (12) is threadedly connected to the first drive screw (31). The top of the first drive screw (31) is fixedly connected to the first worm gear (32). The outer side of the first worm gear (32) is meshed with the first worm (33). The first worm (33) extends to the top of the movable frame (12) and is fixedly connected to the transmission rod (49).

7. A stepped clamping fixture for easily deformable thin-walled workpieces according to claim 1, characterized in that: The drive rod (17) is rotatably connected to the moving frame (2). The top of the drive block (16) is fixedly connected to a drive gear (34). Both sides of the drive gear (34) are meshed with drive racks (35). The drive racks (35) are fixedly connected to the moving frame (2). The drive racks (35) are slidably connected to the base body (1). The bottom of the drive block (16) is fixedly connected to a second worm gear (36). The outer side of the second worm gear (36) is meshed with a second worm (37). The outer side of the second worm (37) is fixedly connected to the drive end of the first drive motor (38).

8. A stepped clamping fixture for easily deformable thin-walled workpieces according to claim 1, characterized in that: The locking block (19) is rotatably connected to the moving frame (2). A fourth compression spring (39) is fixedly connected to the outer side of the locking block (19). The fourth compression spring (39) is fixedly connected to the moving frame (2). The locking block (19) extends to the outer side of the moving frame (2) and is fixedly connected to a lever (40).

9. A stepped clamping fixture for easily deformable thin-walled workpieces according to claim 1, characterized in that: A piston (41) is slidably connected inside the connecting cylinder (20). A second drive screw (42) is rotatably connected inside the connecting cylinder (20) and inside the piston (41). A synchronous wheel (43) is fixedly connected to the bottom of the second drive screw (42). The two sets of synchronous wheels (43) are connected by a synchronous belt (44). A second drive motor (45) is fixedly connected inside the base body (1) and at the bottom of one set of synchronous wheels (43). The drive end of the second drive motor (45) is fixedly connected to one set of synchronous wheels (43). An air inlet (46) and an air outlet (47) are respectively opened at the top of the connecting cylinder (20). A closing plate (48) is rotatably connected to the outside of the air inlet (46) and the air outlet (47). The closing plate (48) is connected to the connecting cylinder (20) by a torsion spring. The connecting cylinder (20) is connected to the suction cup (21) through the air inlet (46) and the air outlet (47).

10. A method of using the stepped clamping fixture for easily deformable thin-walled workpieces as described in claims 1-9, characterized in that, The method of use includes the following steps: S1: Fixture initialization and workpiece vacuum pre-positioning: Place the workpiece at the center of the top surface of the base body (1), start the adsorption assembly (8), and drive the piston (41) downward through the second drive motor (45) to form a negative pressure in the connecting cylinder (20), and complete the vacuum adsorption positioning of the bottom surface of the workpiece by the suction cup (21). S2: Bidirectional synchronous flexible clamping limit: The first drive motor (38) of the start adjustment component (7) drives the two sets of moving frames (2) to feed towards each other synchronously through the drive block (16), drive gear (34), drive rack (35) and drive rod (17), and the workpiece side wall is flexibly limited by the elastic clamping block (11), first damping spring (24) and first compression spring (25) of the clamping component (3); S3: Stepped adaptive clamping and auxiliary locking: Rotate the transmission rod (49), and drive the moving frame (12) downward through the first worm (33), the first worm wheel (32), and the first drive screw (31), so that the elastic block (15), the flexible connecting sleeve (14), and the second compression spring (26) of the fitting component (4) achieve stepped adaptive clamping on the top surface of the workpiece; rotate the limit rod (5), and the limit locking is completed by the ratchet (18), the locking block (19), and the fourth compression spring (39) of the locking component (6); S4: Staged cutting and status monitoring: switch clamping force according to roughing and finishing, start machine tool processing; monitor the vacuum degree and clamping status of the chuck (21) throughout the process, use micro-lubrication and cooling to ensure processing accuracy and workpiece non-deformation; S5: Grading, workpiece removal and fixture reset: After processing, allow the workpiece to stand still to release pressure. Grading is performed in the following order: unlocking limit rod (5), lifting the bonding component (4), retracting the moving frame (2), and releasing the suction cup (21). The workpiece is then removed smoothly, cleaned, and each component is reset.

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