High-precision shaft pneumatic tooling

Abstract

The application discloses a high-precision shaft pneumatic tool. The tool comprises a cylinder, a bottom plate, a base, a plurality of elastic clamps, a pressing plate, a pull core, a guide column, a guide sleeve and a plurality of axial positioning columns. The base is provided with a plurality of clamp mounting holes corresponding to the elastic clamps, and the pressing plate is provided with a pressing hole matched with the upper end of the elastic clamp. The cylinder drives the pressing plate to make axial reciprocating motion relative to the base through the pull core. The guide column and the guide sleeve limit the movement of the pressing plate along the axial direction. The axial positioning columns installed on the bottom plate are coaxially arranged with the elastic clamps. The air pressure regulating valve is arranged on the inlet circuit of the cylinder. When the pressing plate is moved towards the base by the pull core, the elastic clamp is radially contracted and self-centered to clamp the workpiece. Conversely, the elastic clamp is opened by its own elasticity to release the workpiece. The application can effectively reduce the clamping deformation and surface damage of small shaft parts, improve the radial run-out control ability, the repeat positioning accuracy, the multi-station machining consistency and the change efficiency.

Description

Technical Field

[0001] This invention belongs to the field of machining tooling and fixture technology, and particularly relates to a pneumatic tooling for high-precision, low-deformation clamping of small shaft parts. Background Technology

[0002] In the field of precision machinery manufacturing, small shaft parts are widely used in products such as micro motors, aerospace, precision instruments, and medical devices. These parts typically have small diameters, large length-to-diameter ratios, and poor overall rigidity. Under the combined action of cutting and clamping forces, they are prone to bending deformation, elliptical deformation, and surface indentation, which affects the roundness, coaxiality, surface integrity, and final dimensional accuracy of the parts.

[0003] Existing clamping methods for small shaft parts mainly include three-jaw chuck clamping and V-block clamping. Three-jaw chucks typically use manual locking, making it difficult to maintain uniform clamping force. This can easily cause localized overpressure and surface damage when clamping small shaft parts. Furthermore, when the workpiece diameter is small, it is difficult to set a reliable end-face limiting structure at the center of the chuck, resulting in unstable workpiece extension and poor axial positioning accuracy. While the V-block clamping solution has a relatively simple structure, the clamping force is also difficult to control precisely, easily causing workpiece bending, indentation, and elliptical deformation. Additionally, it has low repeatability and cannot meet the requirements for high-consistency machining.

[0004] Furthermore, most existing fixtures use manual single-piece clamping, making it difficult to standardize production cycles, resulting in high labor costs and low efficiency in mass production. When processing products of different specifications, it is often necessary to remake tooling or realign fixtures, leading to long changeover times, poor versatility, and difficulty in stable integration with robotic arms or automatic loading and unloading systems, thus hindering the construction of automated production lines.

[0005] While existing technologies include chuck structures for clamping small shaft parts, elastic chuck structures with axial positioning structures, and cylinder-driven spring chuck structures, there is still a lack of high-precision pneumatic tooling for shafts that can integrate pneumatic drive, precise centering, anti-deviation guidance, axial limiting, controllable clamping force, and multi-station consistency. Summary of the Invention

[0006] The purpose of this invention is to provide a high-precision pneumatic tooling for shafts to solve the following technical problems existing in the clamping process of small shaft parts: uneven clamping force that is difficult to control, which easily causes workpiece deformation and surface damage; lack of stable and reliable axial limiting and internal support, which makes it difficult to unify the workpiece extension and make it susceptible to vibration and deviation due to cutting force during processing; the clamping parts are prone to skew during movement, making it difficult to ensure clamping concentricity, repeatability, and consistency of multi-station processing; and low changeover efficiency, making it difficult to adapt to the needs of batch, flexible and automated production.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution.

[0008] A high-precision pneumatic tooling for clamping small shaft parts includes a cylinder, a base plate, a base, multiple elastic chucks, a pressure plate, a pull core, guide posts, guide sleeves, and multiple axial positioning posts. The base plate is fixedly mounted on the cylinder, and the base is fixedly mounted on the base plate. The base has multiple chuck mounting holes, with the lower end of each elastic chuck positioned within a corresponding mounting hole. The pressure plate is located on the side of the base away from the cylinder, and has clamping holes corresponding to the upper ends of the elastic chucks, each clamping hole having a mating surface that engages with the corresponding upper end of the elastic chuck. The pull core extends axially, with one end fixedly connected to the movable end of the cylinder and the other end fixedly connected to the pressure plate, allowing the cylinder to drive the pressure plate to reciprocate axially relative to the base. The guide posts and guide sleeves are correspondingly positioned between the base and the pressure plate to restrict the pressure plate to move only axially. Multiple axial positioning pins are coaxially arranged with multiple elastic chucks and are axially adjustable on the base plate. A pressure regulating valve is provided on the air inlet circuit of the cylinder to regulate the axial driving force output by the cylinder to the pull core. Specifically, when the cylinder drives the pull core to move the pressure plate toward the base, the mating surface applies axial pressure to the multiple elastic chucks, causing them to radially contract and self-center to clamp the workpiece. When the cylinder reverses its direction, driving the pull core to move the pressure plate away from the base, the mating surface releases the axial pressure on the multiple elastic chucks, and the multiple elastic chucks radially open due to their elasticity to release the workpiece.

[0009] Preferably, there are four chuck mounting holes, which are symmetrically distributed in a rectangle around the core, and the four elastic chucks correspond to form a four-station synchronous clamping structure.

[0010] Preferably, there are four sets of guide posts, each set of which slides in a corresponding manner with the guide sleeve and is symmetrically distributed around the periphery of the plurality of clamp mounting holes to form a four-sided limiting and guiding structure for the pressure plate.

[0011] Preferably, the elastic clamp includes a first tapered surface at the upper end and a second tapered surface at the lower end.

[0012] Preferably, the mating surface is a third tapered surface that mates with the first tapered surface, and the mating half angle between the two is 20°±0.05°; the contact area between the mating surface and the first tapered surface is not less than 85%, and the surface roughness Ra of the mating surface and the first tapered surface is not greater than 0.2μm; in a multi-station state, the angle difference between the corresponding tapered surfaces of each station is not greater than 0.02°.

[0013] Preferably, the axial positioning column is a two-stage stepped precision cylindrical structure. The axial positioning column is laterally locked to the base plate by positioning column fixing screws and can be independently adjusted along the axial direction.

[0014] Preferably, one end of the pull core is threadedly connected to the movable end of the cylinder, and the other end is provided with a stepped portion. The stepped portion is connected to the countersunk hole on the pressure plate and is locked and fixed by the pull core locking screw.

[0015] Preferably, the base plate is fixed to the cylinder by a plurality of base plate locking screws, and the base is fixed to the base plate by a plurality of base locking screws.

[0016] Preferably, the air pressure regulating valve is used to adjust the input air pressure to 0.25MPa to 0.7MPa so that a single elastic chuck generates a radial clamping force of 300N to 1700N on the workpiece.

[0017] Preferably, both the elastic clamp and the axial positioning post are replaceable modules.

[0018] Compared with the prior art, the present invention has at least the following beneficial effects: First, this invention establishes a stable conversion chain of "axial driving force - axial clamping force - radial clamping force" by setting the force transmission and cooperation relationship between the cylinder, pull core, pressure plate, elastic chuck, and base chuck mounting hole. Because the mating surface of the pressure plate precisely matches the upper outer wall surface of the elastic chuck 6, the axial driving force output by the cylinder 13 can be stably converted into a uniform radial clamping force on the workpiece by multiple elastic chucks 6. This avoids indentations, pinch marks, and elliptical deformation caused by localized overpressure in traditional hard-contact fixtures, and solves the technical problem of difficult-to-control clamping force and easy surface damage to small shaft parts.

[0019] Secondly, this invention restricts the pressure plate to move only axially by setting guide posts and guide sleeves between the base and the pressure plate, and by utilizing the one-to-one sliding fit between the guide posts and guide sleeves. This prevents the pressure plate from tilting or leaning to one side when driven by the pull core. Because the pressure plate is forcibly restricted to pure axial movement, the axial pressure on the elastic chucks at each station can remain synchronous and uniform, thereby reducing the radial runout of the workpiece and improving coaxiality, roundness, and repeatability.

[0020] Furthermore, this invention incorporates an axially adjustable positioning post at the center of each elastic chuck. This axial positioning post, on the one hand, limits the insertion depth of the workpiece, ensuring consistent axial extension; on the other hand, it provides internal support to the clamping end of slender workpieces, reducing vibration and displacement caused by insufficient workpiece rigidity during cutting. Therefore, the axial positioning post solves the problem of unstable axial positioning of small shaft-like parts in traditional fixtures, and also improves the workpiece's resistance to deformation and the consistency of multi-part machining.

[0021] Furthermore, this invention incorporates a pressure regulating valve in the cylinder's air intake circuit. The operator can adjust the cylinder's output driving force according to the workpiece's diameter, material, and process requirements, ensuring that the radial clamping force of the elastic chuck matches the workpiece's rigidity. Because the clamping force can be precisely adjusted, this invention achieves low-deformation clamping while maintaining clamping reliability, making it particularly suitable for ultra-fine workpieces with large length-to-diameter ratios or high surface quality requirements.

[0022] Furthermore, this invention preferably employs a multi-station synchronous clamping structure, and both the elastic chuck and the axial positioning post are modular and replaceable components. The multi-station synchronous clamping structure allows for the simultaneous positioning and clamping of multiple workpieces in a single setup, which improves clamping efficiency, reduces dimensional variations between different workpieces, and facilitates automated integration, supporting robotic arms or automated loading / unloading systems to meet the needs of intelligent manufacturing. The modular replacement structure allows for tooling changes when processing workpieces of different specifications by simply replacing the elastic chuck and the axial positioning post, eliminating the need for complete tooling remanufacturing. This significantly shortens changeover time and improves versatility and automation adaptability. Attached Figure Description

[0023] Figure 1 This is a three-dimensional structural schematic diagram of a high-precision shaft-type pneumatic tooling according to an embodiment of the present invention.

[0024] Figure 2 This is an exploded structural diagram of a high-precision shaft-type pneumatic tooling according to an embodiment of the present invention.

[0025] Figure 3 This is a top view of a high-precision shaft-type pneumatic tooling according to an embodiment of the present invention.

[0026] Figure 4 for Figure 3 A cross-sectional view along the AA direction.

[0027] Figure 5 for Figure 3 A cross-sectional view along the BB direction.

[0028] Figure 6 for Figure 3 A sectional view along the CC direction.

[0029] Figure 7 This is a schematic diagram of the assembly of an elastic clamp, an axial positioning post, and a positioning post fixing screw according to an embodiment of the present invention.

[0030] Figure 8 This is a schematic diagram of the upper surface structure of the pressure plate according to an embodiment of the present invention.

[0031] Figure 9 This is a schematic diagram of the lower surface structure of the pressure plate according to an embodiment of the present invention.

[0032] Figure 10 This is a schematic diagram of the upper surface structure of the base according to an embodiment of the present invention.

[0033] Figure 11 This is a schematic diagram of the lower surface structure of the base according to an embodiment of the present invention.

[0034] Figure 12 This is a schematic diagram of the upper surface structure of the base plate according to an embodiment of the present invention.

[0035] Figure 13 This is a schematic diagram of the lower surface structure of the base plate according to an embodiment of the present invention.

[0036] Figure 14 This is a schematic diagram of the assembly of the pull core and the pull core locking screw according to an embodiment of the present invention.

[0037] Figure 15 This is a schematic diagram of an axial positioning column structure according to an embodiment of the present invention.

[0038] Figure 16 This is a schematic diagram of a cylinder structure according to an embodiment of the present invention.

[0039] Figure 17 This is a three-dimensional schematic diagram of the hidden pressure plate of a high-precision shaft-type pneumatic tooling according to an embodiment of the present invention.

[0040] Figure 18 This is a three-dimensional schematic diagram of a high-precision shaft-type pneumatic tooling concealing the pressure plate and base according to an embodiment of the present invention.

[0041] In the diagram: 1. Pull core locking screw; 2. Pull core; 3. Pressure plate; 31. Pressing hole; 32. Countersunk hole; 33. Guide sleeve fixing hole; 4. Base locking screw; 5. Guide sleeve; 6. Elastic chuck; 61. First tapered surface; 62. Second tapered surface; 7. Guide post; 8. Base; 81. Chuck mounting hole; 82. First pull core clearance hole; 83. Guide post fixing hole; 9. Base plate locking screw; 10. Axial positioning post; 11. Positioning post fixing screw; 12. Base plate; 121. Second pull core clearance hole; 122. Positioning post fixing hole; 123. Base plate screw fixing hole; 13. Cylinder; 131. Pull core fixing hole; 132. First air pipe interface; 133. Second air pipe interface. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] This invention provides a high-precision pneumatic tooling for shafts, used to clamp small shaft parts, especially solid cylindrical parts with small diameters, large length-to-diameter ratios, and prone to deformation during clamping and cutting. Preferably, these are workpieces with a diameter of 0.5mm–10mm, a length of 5mm–80mm, a length-to-diameter ratio of 5–15, and materials such as aluminum, copper, 45# steel, stainless steel, cemented carbide, and PEEK / POM engineering plastics. Ceramic workpieces, thin-walled hollow shafts, and workpieces with loosely coated surfaces are not preferred for this embodiment. Applicable processes include external turning, drilling, micro-milling, polishing, and light knurling. It can be used in conjunction with automated robotic arms for loading and unloading to achieve intelligent manufacturing.

[0044] The high-precision shaft pneumatic tooling provided in this embodiment of the invention includes a cylinder 13, a base plate 12, a base 8, multiple elastic chucks 6, a pressure plate 3, a pull core 2, a guide post 7, a guide sleeve 5, and multiple axial positioning posts 10. The base plate 12 is fixedly mounted on the cylinder 13, and the base 8 is fixedly mounted on the base plate 12. The base 8 is provided with multiple chuck mounting positions, each chuck mounting position is provided with a chuck mounting hole 81, and the lower end of each elastic chuck 6 is respectively disposed in the corresponding chuck mounting hole 81. The pressure plate 3 is located on the side of the base 8 away from the cylinder 13, and the pressure plate 3 is provided with clamping holes 31 corresponding one-to-one with the upper ends of the multiple elastic chucks 6, and each clamping hole 31 has a mating surface that mates with the upper end of the corresponding elastic chuck 6. The core 2 extends axially, with one end fixedly connected to the movable end of the cylinder 13 and the other end fixedly connected to the pressure plate 3, so that the cylinder 13 drives the pressure plate 3 to reciprocate axially relative to the base 8. The guide post 7 and the guide sleeve 5 are correspondingly arranged between the base 8 and the pressure plate 3 to restrict the pressure plate 3 to move only axially. Multiple axial positioning posts 10 are coaxially arranged with multiple elastic clamps 6 and are axially adjustable on the base plate 12. A pressure regulating valve is provided on the air intake circuit of the cylinder 13 to regulate the axial driving force output by the cylinder 13 to the core 2. When the cylinder 13 drives the core 2 to move the pressure plate 3 toward the base 8, the mating surface of the pressure plate 3 applies axial pressure to the multiple elastic chucks 6, causing the multiple elastic chucks 6 to radially contract and self-center to clamp the workpiece; when the cylinder 13 drives the core 2 in the opposite direction to move the pressure plate 3 away from the base 8, the mating surface of the pressure plate 3 releases the axial pressure on the multiple elastic chucks 6, and the multiple elastic chucks 6 rely on their own elasticity to radially open and release the workpiece.

[0045] like Figures 1-18 As shown, a specific embodiment of the present invention provides a four-station high-precision shaft pneumatic tooling, including a cylinder 13, a base plate 12, a base 8, a pressure plate 3, a pull core 2, a pull core locking screw 1, a base locking screw 4, a guide sleeve 5, an elastic chuck 6, a guide post 7, a base plate locking screw 9, an axial positioning post 10, a positioning post fixing screw 11, a first air pipe interface 14, and a second air pipe interface 15. Figure 7 As shown, the elastic clamp 6 includes a first tapered surface 61 at the upper end and a second tapered surface 62 at the lower end. Figure 1 , Figure 17 , Figure 18As shown, the base plate 12 is installed on the upper end of the cylinder 13 and is fixedly connected to the cylinder 13 by four base plate locking screws 9; the base 8 is set above the base plate 12 and is fixed to the base plate 12 by four base locking screws 4 to form the main support frame of the tooling. The pressure plate 3 is set above the base 8.

[0046] like Figure 10 , Figure 11 , Figure 17 As shown, four chuck mounting positions are formed on the base 8, and each chuck mounting position is symmetrically distributed in a rectangle around the core 2. Each chuck mounting position has a chuck mounting hole 81 that matches the lower end of the elastic chuck 6. The chuck mounting hole 81 protrudes from the surface of the base 8 in the direction near the pressure plate 3. The chuck mounting hole 81 has a fourth tapered surface that mates with the second tapered surface 62 of the corresponding elastic chuck 6. The four elastic chucks 6 are respectively installed in the four chuck mounting holes 81, and the second tapered surface of each elastic chuck 6 mates with the fourth tapered surface of the corresponding chuck mounting hole 81 so as to generate radial contraction when subjected to axial pressure applied by the pressure plate 3.

[0047] like Figure 8 , Figure 9 As shown, the pressure plate 3 has clamping holes 31 corresponding to four elastic chucks 6. Each clamping hole 31 has a third tapered surface that mates with the first tapered surface 61 of the corresponding elastic chuck 6. In a preferred embodiment, the half-angle of the mating between the third tapered surface of the clamping hole 31 and the first tapered surface of the elastic chuck 6 is 20°±0.05°, the mating contact area is not less than 85%, the surface roughness Ra is not greater than 0.2μm, and the angle difference between the corresponding tapered surfaces of the four positions is not greater than 0.02°. With these mating parameters, a high-precision, low-friction, and non-self-locking force transmission interface can be formed between the pressure plate 3 and the elastic chucks 6, allowing the axial displacement of the pressure plate 3 to be stably converted into the radial uniform clamping action of the elastic chucks 6, thus achieving low runout, long service life, and high repeatability. While the tapered surface of ordinary fixtures only serves as a guide or for coarse clamping, in this embodiment, the tapered surface of the tooling is a precision force conversion and centering reference.

[0048] like Figure 1 , Figure 4 , Figure 6 , Figure 8 , Figure 9 , Figure 14As shown, the pull core 2 is located between the cylinder 13 and the pressure plate 3, and is used to rigidly transmit the axial driving force output by the cylinder 13 to the pressure plate 3. In this invention, the pull core 2 preferably only transmits axial force and does not undertake the function of transmitting yaw torque. The pull core 2 is arranged along the central axis of the tooling, one end of which is connected to the movable end of the cylinder 13 by a thread, and the other end has a stepped portion that extends into the countersunk hole 32 on the pressure plate 3 and is locked in place by the pull core locking screw 1, thereby realizing a rigid force transmission connection between the cylinder 13 and the pressure plate 3. Figures 10-13 , Figure 16 As shown, the base 8 has a first core-pulling clearance hole 82 for the core puller 2 to pass through, the base plate 12 has a second core-pulling clearance hole 121 for the core puller 2 to pass through, and the cylinder 13 has a core-pulling fixing hole 131. The core-pulling fixing hole 131 has an internal thread that mates with the external thread at the lower end of the core puller 2. The cylinder 13 is preferably a double-acting cylinder, with a first air pipe interface 14 and a second air pipe interface 15 on its side. An air pressure regulating valve is located on the air inlet circuit of the cylinder 13 and is used to adjust the output force of the cylinder 13 according to the workpiece material and size. Preferably, the input air pressure can be adjusted to 0.25MPa to 0.7MPa, corresponding to a radial clamping force of 300N to 1700N for the single-station elastic chuck 6. Specifically, when the input air pressure is around 0.25 MPa, the radial clamping force of the single-station elastic chuck 6 is 300–450 N, suitable for mirror finishing of soft, slender shafts made of aluminum, copper, and engineering plastics; when the input air pressure is 0.3 MPa–0.4 MPa, the radial clamping force of the single-station elastic chuck 6 is 450–750 N, suitable for light cutting, deburring, and polishing of conventional small steel shafts with diameters of 1 mm–5 mm; when the input air pressure is 0.4 MPa–0.5 MPa, the radial clamping force of the single-station elastic chuck 6 is… The radial clamping force is 750-1100N, suitable for ordinary turning and drilling of medium diameter steel shafts with a diameter of 5mm-10mm; when the input air pressure is 0.5MPa-0.6MPa, the radial clamping force of the single-station elastic chuck 6 is 1100-1500N, suitable for high load conditions such as carbide shafts and stainless steel shafts; 0.7MPa is the upper limit pressure, and the radial clamping force of the single-station elastic chuck 6 is 1500-1700N, which is only suitable for temporary conditions of short and thick rigid shafts and is not suitable for long-term continuous use.

[0049] like Figure 17As shown, to ensure that the pressure plate 3 does not tilt during movement, four sets of guide posts 7 and guide sleeves 5 are provided between the base 8 and the pressure plate 3. The guide posts 7 are fixedly installed in the guide post fixing holes 83 on the side of the base 8 near the pressure plate 3, and the guide sleeves 5 are embedded in the guide sleeve fixing holes 33 on the side of the pressure plate 3 near the base 8. The guide posts 7 and guide sleeves 5 are slidably fitted one-to-one and are symmetrically distributed around the periphery of the four chuck installation positions, forming a four-sided limiting and guiding structure. The force transmission chain during clamping in this embodiment of the invention is as follows: the cylinder outputs axial pulling force → the pull core pulls the pressure plate in the center → the four sets of guide posts and guide sleeves synchronously support the pressure plate → the conical surface of the pressure plate synchronously and evenly presses down on the four elastic chucks → the chucks radially and evenly contract to clamp the workpiece. Since the four sets of guide posts 7 and guide sleeves 5 provide circumferential uniform support to the pressure plate 3, when the pull core 2 drives the pressure plate 3 to move, the pressure plate 3 can only move up and down axially and cannot swing, thus ensuring that the elastic chucks 6 at the four positions are simultaneously subjected to uniform axial pressure. Without guide posts and sleeves, the pressure plate is only subjected to the pulling force of the core at its center, which easily leads to problems such as large downward pressure in the middle and small downward pressure on both sides, excessive clamping force on one side and insufficient clamping force on the other side. Traditional V-shaped pressure blocks and ordinary spring collets do not have guide posts and sleeves, so the pressure plate is prone to tilting or tilting on one side, and the conical surface is deviated by force. The radial runout of the workpiece is generally in the range of 0.02mm to 0.05mm. The embodiment of this invention relies on guide posts and sleeves for forced guidance, which significantly reduces the difference in downward pressure between the middle and the edge of the pressure plate 3, avoiding the phenomenon of excessive clamping force at one station and insufficient clamping force at another station. The radial runout of the workpiece is reduced by more than 60%, which greatly improves the machining accuracy of the roundness and coaxiality of small shafts.

[0050] like Figure 7 , Figure 18 As shown, each elastic clamp 6 is also provided with an axial positioning post 10. The axial positioning post 10 is coaxially arranged with the corresponding elastic clamp 6 and is laterally locked in the positioning post fixing hole 122 of the base plate 12 by the positioning post fixing screw 11. Figure 15 As shown, the axial positioning column 10 is preferably a two-section stepped precision cylindrical structure. Its upper end extends into the center of the elastic chuck 6, serving both axial limiting and internal rigid support functions to restrict the insertion depth of the workpiece. Its lower part constitutes the installation and adjustment section. By loosening the positioning column fixing screw 11, the axial positioning column 10 can be independently slidably adjusted axially, and then re-locked after reaching the desired extension amount. Because the axial positioning column 10 adopts a standardized installation reference design, the operator can quickly insert and remove the corresponding axial positioning column 10 when changing workpieces of different specifications. This structure not only adapts to continuous adjustment of workpieces of the same diameter but also allows for single-piece replacement after wear, reducing maintenance costs and improving changeover efficiency.

[0051] The elastic chuck 6 in this embodiment also adopts a standardized, replaceable modular structure. For workpieces of different diameters, simply remove the original elastic chuck 6 and install an elastic chuck 6 with the corresponding hole diameter and tapered surface size to complete the tooling adaptation, without having to re-process the entire tooling. The modular cooperation between the elastic chuck 6 and the axial positioning post 10 enables this invention to adapt to small shaft parts with diameters of 0.5mm to 10mm, lengths of 5mm to 80mm, and length-to-diameter ratios of 5 to 15.

[0052] The clamping process of the present invention will be described below.

[0053] In the clamping preparation state, cylinder 13 is positioned so that pressure plate 3 is relatively far from base 8. The elastic chucks 6 are not subjected to continuous axial pressure from pressure plate 3, and rely on their own elasticity to maintain a relatively open state. Workpieces can be inserted axially into each elastic chuck 6, with the insertion depth limited by the corresponding axial positioning pin 10. In this state, through the guiding action of guide pin 7 and guide sleeve 5, pressure plate 3 remains parallel to base 8, creating conditions for subsequent synchronous clamping actions.

[0054] When workpiece clamping is required, air is supplied to cylinder 13 through the first air pipe interface 15 and exhausted through the second air pipe interface 16, or an equivalent air path switching method is used to make cylinder 13 output a driving force to push the core 2 to move axially. The core 2 rigidly transmits this driving force to the pressure plate 3, causing the pressure plate 3 to move axially toward the base 8. Since the mating surface of the clamping hole 31 of the pressure plate 3 is precisely fitted with the upper outer wall of the elastic chuck 6, after the pressure plate 3 applies axial pressure to the elastic chuck 6, the elastic chuck 6 generates radial uniform contraction within the chuck mounting hole 81 of the base 8, thereby forming a 360° self-centering clamping around the outer periphery of the workpiece. Since the four stations share the same pressure plate 3 and the same cylinder 13 for driving, the clamping actions of each station can be completed synchronously, thus ensuring the positioning and processing consistency of multiple workpieces.

[0055] In the clamped state, the end of the workpiece abuts against the axial positioning post 10. The radial position of the workpiece is determined by the self-centering of the elastic chuck 6, and the axial position is defined by the axial positioning post 10. Since the axial positioning post 10 extends into the workpiece clamping end and forms a support, the workpiece is less likely to wobble or shift due to cutting forces during subsequent machining processes such as turning, drilling, micro-milling, polishing, and light knurling. At the same time, the guide post 7 and guide sleeve 5 continuously constrain the posture of the pressure plate 3, ensuring that the force is balanced at each station throughout the clamping process, thereby effectively reducing the radial runout of the workpiece and improving its roundness and coaxiality.

[0056] When it is necessary to release the workpiece, the air path is switched so that air enters through the second air pipe interface 16 and exhausts through the first air pipe interface 15, or an equivalent reverse drive method is used to make the cylinder 13 drive the pull core 2 and the pressure plate 3 to move away from the base 8. At this time, the pressure plate 3 releases the axial pressure applied to the elastic chuck 6, and the elastic chuck 6 opens radially due to its own elasticity. The workpiece is released and can be removed by a robot or manually. Since this invention uses pneumatic drive, the clamping and releasing actions at each station can be stably repeated, making it suitable for docking with automatic loading and unloading systems or robots, and meeting the requirements of automated production lines for stable cycle time and consistent action.

[0057] In summary, this invention, through the coordinated combination of cylinder 13, pull core 2, pressure plate 3, elastic chuck 6, guide post 7, guide sleeve 5, and axial positioning post 10, forms an integrated clamping system that combines pneumatic drive, precise guidance, flexible clamping, axial limiting, internal support, and multi-station synchronization. This effectively solves the problems of easy deformation, easy clamping, difficulty in stable positioning, and poor batch consistency of small shaft parts during clamping. The design principle of this invention is a complete closed loop of pneumatic drive, precise centering, anti-deviation guidance, axial limiting, and uniform clamping; none of these components can be omitted. The absence of any one component will lead to deformation, eccentricity, clamping, and positioning failure of the small shaft. The cylinder, as a standard pneumatic power source, provides constant pulling / pushing force, can precisely control the force to adapt to thin shafts with diameters of 1.0mm–10mm, and supports multi-station synchronous operation. Power is transmitted through the pull core. The pull core connects the cylinder and the pressure plate, transmitting only axial force without any torque deviation. The rigid connection ensures synchronous force distribution and gapless movement across multiple stations. The pressure plate absorbs axial force and converts it into radial clamping force through conical surface matching, driving multiple elastic chucks to open and close synchronously. It requires the use of guide posts and guide sleeves to prevent skewing. The elastic chucks provide 360° uniform clamping, high self-centering accuracy, no indentation, and quick changeover. The guide posts and guide sleeves provide forced vertical guidance, ensuring chuck concentricity, avoiding machining errors caused by runout, and providing precision support for the coordinated operation of all components. The axial positioning post positions the shaft end and controls the extension, supporting slender shafts to reduce cutting deformation, ensuring uniform machining dimensions for all workpieces, and improving machining accuracy and consistency. The elastic chucks, combined with an adjustable pneumatic clamping method, provide uniform and controllable clamping force with gentle, non-hard contact, significantly reducing part damage, indentation, and elliptical deformation, solving the problem of difficult-to-control clamping force in traditional fixtures. Relying on the self-centering of the elastic chucks and the precise guidance of the guide posts and guide sleeves, radial runout is effectively reduced, significantly improving part roundness, coaxiality, and dimensional accuracy. The standardized conical surface matching and guiding structure eliminate manual errors and jaw gaps, resulting in higher repeatability. The multi-station synchronous design ensures consistent actions, air pressure, and structure across all stations, resulting in excellent consistency in part machining dimensions and geometric tolerances. The modular quick-change structure allows for adaptation to different part specifications simply by replacing the elastic chuck and axial positioning pin, significantly reducing changeover time and enhancing versatility and economy. Pneumatic drive enables the clamping of multiple parts at once, far exceeding the efficiency of manual single-part clamping. It can interface with robotic arms and automated loading / unloading systems, adapting to automated production lines, stabilizing production cycles, and reducing labor costs.

[0058] Table 1 compares the performance of the tooling in this invention with that of a conventional three-jaw chuck with a non-guided spring collet structure. This invention significantly reduces the probability of pinching, indentation, and elliptical deformation of small shaft parts through the uniform clamping of the elastic collet and the flexible force control of the pneumatic regulating valve, improving the yield rate by 15% to 30%. The forced guiding structure formed by the guide post 7 and guide sleeve 5 significantly reduces radial runout and improves repeatability. Compared with traditional single-piece clamping tooling, the four-station synchronous structure of this invention can clamp four workpieces at once, thereby significantly improving production efficiency and reducing manual labor intensity. The modular design eliminates the need for remaking tooling and repeated alignment. Compared with the traditional changeover method that requires complete tooling re-fabrication, this invention only requires replacing the elastic collet 6 and the axial positioning post 10 to complete the switching of workpieces of different specifications, shortening the changeover time to 2 to 5 minutes.

[0059] Table 1

[0060] The above are merely specific embodiments of the present invention and should not be construed as limiting the scope of the present invention. Equivalent variations made by those skilled in the art based on this invention, as well as changes well-known to those skilled in the art, should still fall within the scope of the present invention.

Claims

1. A high-precision shaft pneumatic tool for clamping a small shaft part, characterized in that, Includes cylinder (13), base plate (12), base (8), multiple elastic clamps (6), pressure plate (3), core puller (2), guide post (7), guide sleeve (5) and multiple axial positioning posts (10); The base plate (12) is fixedly mounted on the cylinder (13), and the base (8) is fixedly mounted on the base plate (12); The base (8) is provided with a plurality of clamp mounting holes (81), and the lower end of each elastic clamp (6) is respectively disposed in the corresponding clamp mounting hole (81); The pressure plate (3) is located on the side of the base (8) away from the cylinder (13). The pressure plate (3) is provided with pressing holes (31) that correspond one-to-one with the upper ends of the multiple elastic clamps (6). Each pressing hole (31) has a mating surface that mates with the upper end of the corresponding elastic clamp (6). The core (2) extends axially, with one end fixedly connected to the movable end of the cylinder (13) and the other end fixedly connected to the pressure plate (3), so that the cylinder (13) drives the pressure plate (3) to reciprocate axially relative to the base (8); The guide post (7) and the guide sleeve (5) are respectively disposed between the base (8) and the pressure plate (3) to restrict the pressure plate (3) to move only along the axial direction; The plurality of axial positioning pins (10) are respectively coaxially arranged with the plurality of elastic clamps (6) and are axially adjustable on the base plate (12); The cylinder (13) is equipped with a pressure regulating valve in its air intake circuit, which is used to regulate the axial driving force output by the cylinder (13) to the core (2). When the cylinder (13) drives the pull core (2) to move the pressure plate (3) toward the base (8), the mating surface applies axial pressure to the multiple elastic chucks (6), causing the multiple elastic chucks (6) to radially contract and self-center to clamp the workpiece; when the cylinder (13) drives the pull core (2) in the opposite direction to move the pressure plate (3) away from the base (8), the mating surface releases the axial pressure on the multiple elastic chucks (6), and the multiple elastic chucks (6) open radially by their own elasticity to release the workpiece.

2. The high-precision shaft pneumatic tooling of claim 1, wherein, There are four chuck mounting holes (81), which are symmetrically distributed in a rectangle around the core (2), and the four elastic chucks (6) form a four-station synchronous clamping structure.

3. The high-precision shaft pneumatic tooling of claim 1, wherein, The guide post (7) consists of four sets, which are in one-to-one sliding fit with the guide sleeve (5) and are symmetrically distributed around the periphery of the multiple clamp mounting holes (81) to form a four-sided limiting and guiding structure for the pressure plate (3).

4. The high-precision shaft pneumatic tooling of claim 1, wherein, The elastic clamp (6) includes a first tapered surface (61) at the upper end and a second tapered surface (62) at the lower end.

5. The high-precision shaft pneumatic tooling of claim 4, wherein, The mating surface is a third tapered surface that mates with the first tapered surface (61), and the mating half angle between the two is 20°±0.05°; The contact area between the mating surface and the first tapered surface (61) is not less than 85%, and the surface roughness Ra of the mating surface and the first tapered surface (61) is not greater than 0.2 μm; in the multi-station state, the angle difference between the corresponding tapered surfaces of each station is not greater than 0.02°.

6. The high-precision shaft pneumatic tooling of claim 1, wherein, The axial positioning column (10) is a two-stage stepped precision cylindrical structure. The axial positioning column (10) is locked to the base plate (12) from the side by the positioning column fixing screw (11) and can be independently adjusted along the axial direction.

7. The high-precision shaft pneumatic tooling of claim 1, wherein, One end of the pull core (2) is threaded to the movable end of the cylinder (13), and the other end is provided with a stepped part. The stepped part is connected to the countersunk hole (32) on the pressure plate (3) and is locked and fixed by the pull core locking screw (1).

8. The high-precision shaft pneumatic tooling of claim 1, wherein, The base plate (12) is fixed to the cylinder (13) by a plurality of base plate locking screws (9), and the base (8) is fixed to the base plate (12) by a plurality of base locking screws (4).

9. The high-precision shaft pneumatic tooling of claim 1, wherein, The air pressure regulating valve is used to adjust the input air pressure to 0.25MPa to 0.7MPa so that the single elastic chuck (6) generates a radial clamping force of 300N to 1700N on the workpiece.

10. The high-precision shaft pneumatic tooling of claim 1, wherein, Both the elastic clamp (6) and the axial positioning post (10) are replaceable modules.

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