High-precision self-centering clamping tool

Abstract

The invention discloses a high-precision self-centering clamping tool which comprises a base body, a plurality of clamping units arranged in the circumferential direction of the base body, a center shaft, a driving piece and a decoupling type driving mechanism, and is characterized in that the center shaft is rotatably supported at the center position of the base body; the clamping units are circumferentially arranged around the central shaft and are mounted at the top of the base body; the decoupling type driving mechanism is used for converting the rotary motion of the driving piece into the radial clamping motion of the clamping unit; the decoupling type driving mechanism is configured in the mode that in the continuous rotation process of the driving piece, when the radial movement of any clamping unit is allowed to be blocked, the other clamping units can continue to move in the radial direction till all the clamping units make contact with the contour of the workpiece. The automatic centering and clamping device has the beneficial effects that through the design of the decoupling type driving mechanism, motion decoupling of all the clamping units is achieved, and the centering and clamping precision and stability of irregular workpieces are improved; the purposes that the centering precision is high, and the clamping jaws are not prone to upwarp and floating are achieved.

Description

Technical Field

[0001] This invention relates to the field of machining fixture technology, specifically to a high-precision self-centering clamping fixture. Background Technology

[0002] In machining and precision measurement processes, the clamping and centering accuracy of workpieces directly affects machining quality and measurement accuracy. This is especially true for workpieces with irregular contours, where traditional self-centering clamping fixtures often have several shortcomings. Existing self-centering clamping fixtures typically employ rigidly connected drive mechanisms, with each clamping unit linked together and unable to move independently. When clamping irregular workpieces, if any clamping unit first contacts and is obstructed by the workpiece contour, the other clamping units will also stop moving. This results in the workpiece not being properly clamped by all the clamping units, leading to low centering accuracy, and even situations where the workpiece becomes loose or shifts, affecting subsequent machining or measurement work.

[0003] Meanwhile, existing clamping fixtures often suffer from complex drive mechanisms, low power transmission efficiency, severe wear, poor reset reliability of clamping units, and insufficient ease of operation. The base body is typically a single-piece structure, making assembly, disassembly, and maintenance of internal components inconvenient and resulting in high manufacturing costs. Because they rely on a single inclined plane for transmission and positioning, the clearance, wear, and transmission chain errors between kinematic pairs accumulate directly and are reflected in the final position of the jaws, making it difficult to meet the centering accuracy requirements of high-precision machining. Furthermore, the driving force application point of traditional wedge mechanisms often deviates from the force center of the jaw base. This offset force generates an overturning moment, which can easily cause the jaws to tilt or float around their base during clamping. This not only compromises clamping stability, potentially causing micro-movements in the workpiece during machining, but can also damage the workpiece surface or the jaws themselves due to poor contact, severely impacting machining reliability and safety.

[0004] Therefore, there is an urgent need for a new type of clamping tool that can fundamentally solve the above problems. Summary of the Invention

[0005] The present invention aims to solve the problems of low centering accuracy and easy upward floating of the chuck jaws mentioned in the background art, and provides a high-precision self-centering clamping fixture with high centering accuracy and easy upward floating of the chuck jaws.

[0006] A high-precision self-centering clamping fixture includes a base body, multiple clamping units arranged circumferentially thereon, a central shaft, a driving component, and a decoupled driving mechanism.

[0007] The central shaft is rotatably supported at the center of the base body, and the clamping unit is arranged circumferentially around the central shaft and installed on the top of the base body;

[0008] The decoupled drive mechanism is installed inside the base body, and the decoupled drive mechanism converts the rotational motion of the drive component into the radial clamping motion of the clamping unit.

[0009] The clamping unit is driven to connect with the decoupled drive mechanism, which is configured such that during the continuous rotation of the drive component, when the radial movement of any clamping unit is obstructed, other clamping units can continue to move radially until all clamping units contact the workpiece contour, thereby achieving adaptive centering clamping of irregular workpieces.

[0010] Using the base body as the mounting foundation, the central shaft is rotatably supported at the center of the base body, serving as the reference positioning component for each part. Multiple clamping units are evenly arranged circumferentially around the central shaft on the top of the base body for direct contact with the workpiece for clamping. The drive unit provides rotational driving force, and the decoupled drive mechanism is installed inside the base body as an intermediate power transmission unit. Its core function is to convert the rotational motion of the drive unit into the radial linear motion (towards or away from the central shaft) of the clamping units. Each clamping unit is driven and connected to the decoupled drive mechanism, which has a decoupling function, allowing the movement of each clamping unit to be relatively independent, avoiding mutual interference. Ultimately, all clamping units adaptively conform to the workpiece contour and center, achieving higher centering accuracy. The overall structure is compact, and the drive unit synchronously drives multiple clamping units through the decoupled drive mechanism, resulting in high transmission efficiency, strong clamping stability, and adaptability to the clamping needs of various irregular contour workpieces. This broadens the applicability of the tooling, reduces stress concentration during workpiece clamping, and avoids workpiece deformation or surface scratches. It achieves high centering accuracy and prevents the jaws from tilting or floating upwards.

[0011] Preferably, the decoupled drive mechanism includes a radial sliding block and a tangential transmission block. The tangential transmission block is connected to the central shaft and is configured to slide tangentially along the central shaft in response to the rotation of the drive member. The radial sliding block is driven to the clamping unit and slides radially along the central shaft. The tangential transmission block and the radial sliding block are connected by a mutually cooperating inclined surface structure, so that the tangential sliding of the tangential transmission block can be converted into the radial movement of the radial sliding block. The decoupled drive mechanism consists of a radial sliding block and a tangential transmission block, which are the core transmission components. The tangential transmission block is fixedly connected to the central shaft and can rotate synchronously with the central shaft. The tangential transmission block is configured to slide along the tangential direction of the central shaft (perpendicular to the radial direction of the central shaft) to respond to the rotational driving force of the drive component. The radial sliding block is fixedly connected to the clamping unit and can only slide along the radial direction of the central shaft (closer to or farther from the central shaft) to drive the clamping unit to perform clamping actions. The connection ends of the tangential transmission block and the radial sliding block are provided with mutually adaptable inclined surface structures. Through the meshing of the inclined surfaces, the tangential sliding displacement of the tangential transmission block is converted into the radial sliding displacement of the radial sliding block, thereby realizing the direction conversion of the power. It achieves a smooth and precise conversion from rotary motion to radial clamping motion, with high transmission efficiency and low wear. The inclined plane structure has a simple and reliable fit, eliminating the need for complex transmission components and reducing the manufacturing cost and assembly difficulty of the tooling. At the same time, this structure provides a basis for the realization of decoupling function, ensuring that the tangential sliding of the tangential transmission block can stably drive the radial movement of the radial sliding block, and the movement of each radial sliding block (corresponding to each clamping unit) can be relatively independent, further improving the accuracy and stability of centering and clamping irregular workpieces.

[0012] Preferably, the base body includes an upper body and a lower body, which are coaxially fixedly connected by a central shaft. A removable dust cover is provided on the top of the central shaft, and the dust cover is fixed above the central hole of the upper body by screws or clips. The base body is the basic mounting component for the clamping fixture, and has an overall cylindrical structure, divided into two independent parts: an upper body and a lower body. The upper body is located at the top of the base body, and its top is used to install the clamping unit. An internal space is reserved for the installation and sliding of radial sliding blocks. The lower body is located at the bottom of the base body, and its interior is used to install the lower structure of a partially decoupled drive mechanism and drive components, providing support and protection. The central shaft passes through the center of both the upper and lower bodies, and the upper and lower bodies are coaxially fixedly connected by the central shaft (e.g., through threaded connections, pin connections, etc.), ensuring that the central axes of both are coincident with the axis of the central shaft, thus guaranteeing the coaxiality of the entire base body. The dust cover effectively isolates contaminants such as chips, dust, and coolant from the external environment, preventing them from entering the precision moving parts and avoiding abnormal wear, jamming, or corrosion caused by contamination. Keeping the internal mechanisms clean helps maintain the chuck's high centering accuracy over the long term. The base body is divided into an upper and lower body, employing a split structure design. This facilitates the assembly, disassembly, and maintenance of components such as the decoupled drive mechanism and central shaft within the base body. Simultaneously, the upper and lower bodies are coaxially fixedly connected via the central shaft, ensuring their coaxiality and preventing tilting of the central shaft or displacement of the clamping unit due to base body deformation or assembly deviations. This ensures the centering accuracy and structural stability of the clamping fixture. Furthermore, the split structure allows for the use of different materials and processing techniques according to the functional requirements of each part, reducing overall manufacturing costs and improving the structural strength and service life of the base body.

[0013] Preferably, the driving component is further equipped with a limiting component for limiting the axial displacement of the pull ring. The limiting component includes two separate arc-shaped limiting cards and a pull-down fixing ring. The two limiting cards are symmetrically engaged on the top of the upper pull ring and abut against the upper body for limiting. The pull-down fixing ring is sleeved on the bottom of the lower pull ring and threaded to the central shaft to achieve axial limiting of the lower pull ring. The driving component consists of an upper pull ring and a lower pull ring, both of which are annular structures and coaxially mounted with the central shaft. The upper pull ring is coaxially sleeved on the outer circumference of the central shaft (near the upper body), and its outer circumference is fixedly connected to the tangential transmission block by a pin. One end of the pin is embedded in the outer circumference of the upper pull ring, and the other end is embedded in the end of the tangential transmission block, so that the rotation of the upper pull ring can directly drive the tangential transmission block to slide tangentially. The lower pull ring is coaxially sleeved on the inner circumference of the lower end of the central shaft (near the bottom of the lower body) and is fixedly connected to the central shaft (e.g., by interference fit, key connection, etc.). The upper pull ring and the central shaft are fitted in a way that allows relative rotation but synchronous axial movement. The lower pull ring rotates synchronously with the central shaft and moves synchronously axially, ultimately achieving synchronous rotation of both the upper and lower pull rings with the central shaft, and the upper pull ring can drive the tangential transmission block to move synchronously. The dual-ring structure with upper and lower pull rings provides driving force synchronously from both ends of the central shaft, ensuring uniform force distribution and preventing tilting and wear caused by unilateral force, thus improving the service life and rotational stability of the central shaft. The upper pull ring is connected to the tangential transmission block via a pin, ensuring reliable transmission and precisely driving the tangential transmission block to slide tangentially, achieving efficient power transmission. Both the upper and lower pull rings rotate synchronously with the central shaft, coordinating to drive its rotation and further enhancing the stability of the driving force. This ensures the synchronicity of the movement of each clamping unit (when unobstructed) and facilitates the operation and control of the drive components.

[0014] Preferably, the driving component is further equipped with a limiting component for limiting the axial displacement of the pull ring. The limiting component includes two separate arc-shaped limiting cards and a pull-down fixing ring. The two limiting cards are symmetrically engaged on the top of the upper pull ring and abut against the upper body for limiting. The pull-down fixing ring is sleeved on the bottom of the lower pull ring and threaded to the central shaft to achieve axial limiting of the lower pull ring. The limiting assembly is used to limit the axial displacement of the drive components (upper pull ring and lower pull ring). It consists of two separate arc-shaped limiting clips and a lower pull fixing ring. The two limiting clips are semi-circular ring structures, symmetrically clamped on the top of the upper pull ring, with their bottoms fitting against the top of the upper pull ring and their outer sides abutting against the inner wall of the upper body. Through the limiting effect of the upper body, the upward axial displacement of the upper pull ring is limited. The lower pull fixing ring is a ring structure, sleeved on the bottom of the lower pull ring. The lower pull fixing ring is fixedly connected to the central shaft, with its top fitting against the bottom of the lower pull ring. Through threaded locking, the downward axial displacement of the lower pull ring is limited, thereby achieving axial limiting of the entire drive component. Setting a limiting component on the drive component can effectively limit the axial displacement of the upper and lower pull rings, preventing axial movement of the drive component during rotation and transmission. This would prevent the inclined structure of the tangential transmission block and the radial sliding block from disengaging, interrupting power transmission, or causing the clamping unit to deviate and its centering accuracy to decrease. The limiting component adopts a separate arc-shaped limiting card and a lower fixing ring structure, which is simple in structure, easy to install and disassemble, and reliable in limiting. The two limiting cards are symmetrically clamped on the top of the upper pull ring, which can uniformly limit the axial displacement of the upper pull ring and prevent the upper pull ring from tilting. The lower fixing ring is threaded to the central shaft, which is firm in limiting and at the same time facilitates the adjustment of the axial position of the lower pull ring to adapt to different assembly requirements.

[0015] Preferably, there are multiple tangential transmission blocks and radial sliding blocks, which are evenly distributed around the central axis and linked with the upper pull ring. The inclined plane structures between at least two opposite tangential transmission components and their respective corresponding radial sliding blocks are arranged in opposite directions, so that the unidirectional rotation of the upper pull ring can drive the synchronous opposite or opposite movement of the opposite clamping units. The number of tangential drive blocks and radial sliding blocks is the same as the number of clamping units, and they are all evenly arranged around the central axis. Each tangential drive block is connected to the outer peripheral wall of the upper pull ring by a pin to achieve linkage with the upper pull ring. Each radial sliding block is driven by a clamping unit. The inclined planes of at least two oppositely arranged tangential drive blocks and their corresponding radial sliding blocks have opposite inclination directions (for example, the inclined planes of one set of opposite tangential drive blocks are inclined upwards, and the inclined planes of another set of opposite tangential drive blocks are inclined downwards, and the inclined planes of the corresponding radial sliding blocks match them). This reverse inclined plane structure means that when the upper pull ring rotates in one direction, the opposite tangential drive blocks slide in opposite directions along the tangential direction, thereby driving the opposite radial sliding blocks to move synchronously towards each other (closer to the central axis) or away from each other (away from the central axis) through the inclined plane structure. By setting at least two opposing tangential transmission blocks and radial sliding blocks with opposite inclined plane structures, the upper pull ring can drive the opposing clamping units to move synchronously in opposite directions by rotating in one direction. This eliminates the need for reverse rotation of the driving components to switch between clamping and releasing (or simplifies the switching operation), improving operational convenience. At the same time, multiple evenly distributed transmission blocks and sliding blocks can further enhance the decoupling effect, ensuring that when any clamping unit is obstructed, other clamping units can move flexibly, adapting to more complex irregular workpieces.

[0016] Preferably, the inclined structure includes an inclined protrusion integrally formed on the outer wall of the tangential transmission block, the two sides of the inclined protrusion having a wave-shaped structure, and the inner wall of the radial sliding block having an inclined groove adapted to the inclined protrusion. The radial sliding block achieves transmission connection with the tangential transmission block through the meshing transmission of the inclined protrusion and the inclined groove, and the transmission direction is perpendicular to the sliding direction of the inclined protrusion, constituting one of the motion components of the decoupled motion. The inclined structure consists of an inclined protrusion and an inclined groove, which are mutually compatible. The inclined protrusion is integrally formed on the outer wall of the tangential transmission block, and is long and strip-shaped, extending along the length of the tangential transmission block. Its two opposite sides are wavy (i.e., an alternating concave and convex arc structure). The inclined groove is formed on the inner wall of the radial sliding block. The shape and size of the groove are perfectly matched with the inclined protrusion. The two inner walls of the groove are also set as wavy structures, fitting against the wavy sides of the inclined protrusion. The inclined protrusion is embedded in the inclined groove, realizing the meshing connection between the tangential transmission block and the radial sliding block. The inclined direction of the inclined protrusion forms a preset angle with the tangential sliding direction of the tangential transmission block and is perpendicular to the radial movement direction of the radial sliding block. This allows the tangential sliding displacement of the tangential transmission block to be converted into the radial displacement of the radial sliding block through the inclined meshing, and the movement directions of the two are perpendicular to each other, constituting one of the motion components of the decoupled motion. The integrated inclined protrusion and inclined groove meshing transmission provides high structural strength and a tight fit, preventing slippage during transmission and improving the accuracy and stability of power transmission. The two sides of the inclined protrusion are designed with a wave-shaped structure, which increases the meshing area between the inclined protrusion and the inclined groove, while also acting as a buffer to reduce wear and noise during transmission and extend the service life of the components. Through inclined meshing transmission, the tangential sliding of the tangential transmission block and the radial movement of the radial sliding block are ensured to be perpendicular to each other, forming a component of the decoupled motion, further improving the decoupling function, ensuring the motion independence of each clamping unit, and improving the centering and clamping accuracy.

[0017] Preferably, the clamping unit consists of four sets, each driven by a set of four radial sliding blocks, and arranged in pairs. The clamping unit includes a base claw mounted on the radial sliding block and a chuck mounted on the base claw. The point of application of the driving force of the decoupling drive mechanism acting on the base claw is located at or near the radial force center of the base claw.

[0018] The top of the radial sliding block is integrally formed with an inclined block, and the bottom of the base claw is provided with an inclined groove that matches the inclined block. The base claw achieves a detachable sliding connection of the radial sliding block through the sliding engagement of the inclined block and the inclined groove. The sliding engagement direction forms a preset angle with the movement direction of the base claw, which is used to form another motion component of the decoupled motion. The clamping units consist of four groups, evenly distributed circumferentially along the central axis, arranged in pairs (i.e., opposite groups form a pair). Each clamping unit comprises a base jaw and a chuck jaw. The base jaw is mounted on top of the radial sliding block and driven by the radial sliding block. The chuck jaw is detachably mounted on top of the base jaw using bolts or other means, for direct contact with the workpiece. The point of application of the driving force of the decoupled drive mechanism to the base jaw is located at or near the radial force center of the base jaw (i.e., the force equilibrium point when the base jaw moves radially). The top of the radial sliding block has an integrally formed inclined block (an inclined protrusion), and the bottom of the base jaw has an inclined groove that perfectly matches the shape and size of the inclined block. The inclined block is embedded in the inclined groove to achieve a sliding engagement between the radial sliding block and the base jaw. The sliding engagement direction (oblique) of the inclined block and the inclined groove forms a preset angle (e.g., 45°) with the movement direction of the base jaw (radial along the central axis). This oblique sliding engagement constitutes another motion component of the decoupled motion. The clamping unit adopts a split structure of base jaws and chuck jaws. The chuck jaws can be replaced according to the contour and material of the workpiece, which broadens the application range of the tooling and facilitates the maintenance and replacement of the chuck jaws. The driving force application point is set at the radial force center of the base jaw, which can avoid deformation and tilting caused by uneven force on the base jaw and ensure the motion accuracy of the clamping unit. The radial sliding block and the base jaw are detachably connected through the sliding cooperation of the inclined block and the inclined groove, which makes assembly and disassembly convenient and further enhances the independence and self-adaptive capability of the movement of each clamping unit.

[0019] Preferably, each of the two opposite sides of the radial sliding block has a reset hole, and a reset assembly for driving the radial sliding block to reset is installed in the reset hole. The reset assembly is connected to the upper body to ensure that the radial sliding block returns to its initial position after clamping. The reset assembly is used to drive the radial sliding block to return to its initial position after clamping and is installed in the reset hole of the radial sliding block; each of the two opposite sides of the radial sliding block has a reset hole (circular through hole), and the reset hole extends radially along the radial side of the radial sliding block; the reset assembly is fixedly connected to the upper body to ensure fixed support during reset; a set of reset assemblies is installed in each reset hole, and the two sets of reset assemblies are symmetrically arranged to make the reset force on the radial sliding block uniform; the core function of the reset assembly is to provide elastic reset force. When the radial sliding block moves radially towards the central axis, the reset assembly is compressed or stretched, storing elastic potential energy. When the driving force disappears, the elastic potential energy is released, pushing the radial sliding block to move away from the central axis and return to its initial position. A reset component is installed on the radial sliding block, which can automatically drive the radial sliding block to return to its initial position after clamping (when the drive stops or reverses), thereby resetting the clamping unit without manual operation, improving the ease of operation of the tooling; it avoids offset and jamming during the reset of the radial sliding block, ensuring the centering accuracy of the next clamping; the reset holes are opened on two opposite sides of the radial sliding block, which can make the reset force on the radial sliding block uniform, avoid tilting during the reset process, further improve the stability and accuracy of the reset, and extend the service life of the radial sliding block and the reset component.

[0020] Preferably, the reset assembly includes a reset spring and a limiting bolt. The reset spring is embedded in the reset hole, with one end abutting against the bottom of the reset hole and the other end abutting against the upper body. The limiting bolt passes through the upper body and is threaded to the open end of the reset hole to limit the axial displacement of the reset spring and prevent the reset spring from falling off. The reset assembly consists of a reset spring and a limiting bolt, which are used together. The reset spring is a cylindrical compression spring (or tension spring) that is fitted into the reset hole of the radial sliding block. The outer diameter of the reset spring matches the inner diameter of the reset hole, ensuring that the reset spring can be smoothly compressed and stretched within the reset hole. One end of the reset spring is in close contact with the bottom of the reset hole, and the other end is in close contact with the inner wall of the upper body. The limiting bolt is a cylindrical bolt whose threaded portion passes through a pre-set through hole in the upper body and is threaded to the internal thread of the inner wall of the opening end of the reset hole. The head of the limiting bolt is in contact with the outer wall of the upper body to limit the axial displacement of the reset spring. By tightening the thread of the limiting bolt, the reset spring is confined between the reset hole and the upper body, ensuring that the reset spring will not fall off. With its simple structure, low cost, and reliable reset, the elastic force of the reset spring can be selected according to requirements to adapt to different clamping force needs. The limit bolt passes through the upper body and is threaded to the open end of the reset hole, which can effectively limit the axial displacement of the reset spring and prevent the reset spring from falling off or shifting during compression and tension, ensuring the normal operation of the reset assembly. It further improves the stability and accuracy of the radial sliding block reset and extends the service life of the reset assembly.

[0021] The beneficial effects of this invention are as follows: By designing a decoupled drive mechanism, the motion decoupling of each clamping unit is achieved. When clamping an irregular workpiece, if any clamping unit is obstructed, the other clamping units can continue to move until all clamping units conform to the workpiece contour, thereby improving the centering and clamping accuracy and stability of irregular workpieces. The decoupled drive mechanism adopts the inclined surface meshing transmission of radial sliding block and tangential transmission block, which has a simple and reliable structure, high power transmission efficiency, and low wear.

[0022] The base body adopts a split structure of upper and lower body, which facilitates the assembly, disassembly and maintenance of internal components. At the same time, it is fixed coaxially by the central shaft to ensure the overall coaxiality and avoid assembly deviations from affecting clamping accuracy. The drive component adopts a double-ring structure of upper and lower pull rings, which work together to drive the central shaft to rotate, with uniform force and stable rotation, ensuring the continuity and accuracy of power transmission.

[0023] The clamping unit adopts a four-group paired configuration to clamp the workpiece from four directions, which enhances stability. The radial sliding block and the inclined block-slot of the base claw cooperate to form a double decoupling, further improving the motion independence of each clamping unit.

[0024] The reset component enables automatic reset of the radial sliding block and clamping unit, improving ease of operation. It features a compact structure, low manufacturing cost, convenient operation, and easy maintenance. It can be widely used in precision clamping scenarios for various irregular workpieces, achieving high centering accuracy and preventing the jaws from tilting or floating upwards. Attached Figure Description

[0025] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0026] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0027] Figure 2 This is a schematic diagram of the decoupled drive mechanism;

[0028] Figure 3 This is a schematic diagram of the assembly of the internal structures of the upper body;

[0029] Figure 4 This is a schematic diagram of the assembly of the drive component and the central shaft;

[0030] Figure 5 This is a schematic diagram showing the positional structure of the limiting component and the upper pull ring;

[0031] Figure 6 This is a schematic diagram of the assembly of the pull-down ring and the pull-down retaining ring.

[0032] The components include: 1. Base body; 11. Upper body; 12. Lower body; 2. Central shaft; 3. Driving component; 31. Upper pull ring; 32. Lower pull ring; 4. Decoupled drive mechanism; 41. Tangential transmission block; 411. Oblique protrusion; 42. Radial sliding block; 421. Oblique groove; 422. Oblique block; 423. Reset hole; 5. Clamping unit; 51. Base claw; 511. Oblique groove; 52. Claw; 6. Limiting component; 61. Limiting card; 62. Lower fixing ring; 7. Reset component; 71. Reset spring; 72. Limiting bolt; 8. Dust cover. Detailed Implementation

[0033] The present invention will be further described below with reference to specific embodiments, but the present invention is not limited to the embodiments.

[0034] In the description of this invention, it should be noted that the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer" and "vertical" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0035] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; or they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0036] Furthermore, in the description of this invention, unless otherwise stated, "multiple", "multiple groups", and "multiple roots" mean two or more.

[0037] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments;

[0038] like Figure 1 As shown, a high-precision self-centering clamping fixture includes a base body 1, multiple clamping units 5 arranged circumferentially thereon, a central shaft 2, a driving component 3, and a decoupled driving mechanism 4.

[0039] The central shaft 2 is rotatably supported at the center of the base body 1, and the clamping unit 5 is arranged circumferentially around the central shaft 2 and installed on the top of the base body 1;

[0040] The decoupled drive mechanism 4 is installed inside the base body 1. The decoupled drive mechanism 4 converts the rotational motion of the drive component 3 into the radial clamping motion of the clamping unit 5.

[0041] The clamping unit 5 is driven to connect with the decoupled drive mechanism 4. The decoupled drive mechanism 4 is configured such that, during the continuous rotation of the drive member 3, when the radial movement of any clamping unit 5 is obstructed, other clamping units 5 can continue to move radially until all clamping units 5 contact the workpiece contour, thereby achieving adaptive centering clamping of irregular workpieces.

[0042] like Figure 2As shown, the decoupled drive mechanism 4 includes a radial sliding block 42 and a tangential transmission block 41. The tangential transmission block 41 is connected to the central shaft 2 and is configured to slide tangentially along the central shaft 2 in response to the rotation of the drive member 3. The radial sliding block 42 is driven connected to the clamping unit 5 and slides radially along the central shaft 2. The tangential transmission block 41 and the radial sliding block 42 are connected by a mutually cooperating inclined surface structure, so that the tangential sliding of the tangential transmission block 41 can be converted into the radial movement of the radial sliding block 42.

[0043] like Figure 1 As shown, the base body 1 includes an upper body 11 and a lower body 12. The upper body 11 and the lower body 12 are coaxially fixedly connected by a central shaft 2. A detachable dust cover 8 is also provided on the top of the central shaft 2. The dust cover 8 is fixed above the central hole of the upper body 11 by screws or buckles.

[0044] like Figure 4 As shown, the driving component 3 includes an upper pull ring 31 and a lower pull ring 32. The upper pull ring 31 is coaxially sleeved on the outer peripheral side of the central shaft 2. The tangential transmission block 41 is connected to the outer peripheral wall of the upper pull ring 31 by a pin, thereby driving the tangential transmission block 41 to slide tangentially. The lower pull ring 32 is coaxially sleeved on the inner peripheral side of the lower end of the central shaft 2, and both the upper pull ring 31 and the lower pull ring 32 rotate synchronously with the central shaft 2.

[0045] like Figure 5 and Figure 6 As shown, the drive unit 3 is also equipped with a limiting component 6 for limiting the axial displacement of the pull ring. The limiting component 6 includes two separate arc-shaped limiting cards 61 and a pull-down fixing ring 62. The two limiting cards 61 are symmetrically locked on the top of the upper pull ring 31 and abut against the upper body 11 for limiting. The pull-down fixing ring 62 is sleeved on the bottom of the pull-down ring 32 and threadedly fixed to the central shaft 2 to achieve axial limiting of the pull-down ring 32.

[0046] like Figure 3 As shown, there are multiple tangential transmission blocks 41 and radial sliding blocks 42, which are evenly distributed around the central axis 2 and linked with the upper pull ring 31. The inclined plane structures between at least two opposite tangential transmission blocks 41 and their respective corresponding radial sliding blocks 42 are arranged in opposite directions, so that the unidirectional rotation of the upper pull ring 31 can drive the synchronous opposite or opposite movement of the opposite clamping units 5.

[0047] like Figure 2As shown, the inclined structure includes an inclined protrusion 411 integrally formed on the outer wall of the tangential transmission block 41. The two sides of the inclined protrusion 411 have a wave-shaped structure. The inner wall of the radial sliding block 42 is provided with an inclined groove 421 that matches the inclined protrusion 411. The radial sliding block 42 achieves a transmission connection with the tangential transmission block 41 through the meshing transmission of the inclined protrusion 411 and the inclined groove 421. The transmission direction is perpendicular to the sliding direction of the inclined protrusion 411, forming one of the motion components of the decoupled motion.

[0048] like Figure 3 As shown, there are four sets of clamping units 5, which are driven by four sets of radial sliding blocks 42 respectively, and are arranged in pairs. The clamping unit 5 includes a base claw 51 installed on the radial sliding block 42 and a chuck 52 installed on the base claw 51. The driving force of the decoupled drive mechanism 4 acting on the base claw 51 is located at or near the radial force center of the base claw 51.

[0049] like Figure 2 As shown, the top of the radial sliding block 42 is integrally formed with an inclined block 422, and the bottom of the base claw 51 is provided with an inclined groove 511 that matches the inclined block 422. The base claw 51 slides with the inclined block 422 and the inclined groove 511 to realize the detachable sliding connection of the radial sliding block 42. The sliding engagement direction is at a preset angle with the movement direction of the base claw 51, which is used to form another motion component of the decoupled motion.

[0050] The radial sliding block 42 has a reset hole 423 on each of its two opposite sides. A reset component 7 for driving the radial sliding block 42 to reset is installed in the reset hole 423. The reset component 7 is connected to the upper body 11 to ensure that the radial sliding block 42 returns to its initial position after clamping.

[0051] The reset assembly 7 includes a reset spring 71 and a limiting bolt 72. The reset spring 71 is embedded in the reset hole 423. One end of the reset spring 71 abuts against the bottom of the reset hole 423, and the other end abuts against the upper body 11. The limiting bolt 72 passes through the upper body 11 and is threadedly fixed to the open end of the reset hole 423 to limit the axial displacement of the reset spring 71 and prevent the reset spring 71 from falling off.

[0052] An embodiment of the present invention:

[0053] like Figure 1 As shown, the overall structure consists of: base body 1, central shaft 2, driving component 3, decoupled driving mechanism 4, and four sets of clamping units 5.

[0054] The base body 1 is formed by coaxially fixing the upper body 11 and the lower body 12 together via the central shaft 2, thus forming a rigid support frame. The end face of the upper body 11 is provided with four evenly distributed radial T-slots for mounting the clamping unit 5.

[0055] Drive component 3 and transmission: Drive component 3 includes an upper pull ring 31 and a lower pull ring 32. The upper pull ring 31 is sleeved in the middle of the central shaft 2 via a bearing. A dust cover 8 is installed on the top of the upper pull ring 31, which can be quickly removed and replaced. The outer circumference of the upper pull ring 31 is hinged to four tangential transmission blocks 41 by multiple radial pins. The lower pull ring 32 is fixed to the lower end of the central shaft 2 and mainly serves as an auxiliary support. When an external power (such as a cylinder or hydraulic cylinder) pulls or rotates the central shaft 2, the upper pull ring 31 rotates accordingly.

[0056] like Figure 3 As shown, the kinematic chain is decoupled and error is isolated: the rotational motion of the upper pull ring 31 is directly converted into the left and right sliding of the four tangential transmission blocks 41 along the tangential direction of the disc circumference through a pin connection. Subsequently, this tangential sliding is converted into the radial motion of the radial sliding block 42 through a high-precision inclined plate pair. The kinematic chain is decoupled into two mutually perpendicular and independent motion components: "rotation → tangential sliding" and "tangential sliding → radial movement".

[0057] Specifically, the rotational motion of the drive component 3 is first converted into the pure tangential sliding of the tangential transmission block 41 along the precision guide rail via a pin connection; subsequently, this tangential sliding is converted into the pure radial motion of the radial sliding block 42 via a high-precision inclined plane pair. Each kinematic chain can be independently manufactured, pre-tightened, and adjusted with micron-level precision. This decoupling design achieves error isolation: the gap or error of the tangential sliding chain will not be linearly transmitted and amplified into radial positioning error, thus eliminating the error accumulation effect of traditional single inclined plane transmission at its source.

[0058] like Figure 2 As shown, the optimized driving force application point is achieved by precisely positioning the interface between the top inclined block 422 (or protrusion) of the radial sliding block 42 and the inclined groove 511 at the bottom of the base claw 51 within ±2mm of the theoretical force centerline of the base claw 51. This design ensures that the driving force passes approximately through the center of force of the claw 52, ​​reducing the eccentric torque that would cause the claw 52 to tilt upwards by more than 30%-40%, ensuring that the claw 52 and the workpiece achieve uniform contact across the entire plane, and eliminating the micron-level center offset caused by the deflection of the claw 52.

[0059] Precision fit and active backlash elimination: The transmission ramp between the tangential transmission block 41 and the radial sliding block 42 adopts a multi-peak wave-shaped structure, forming a large-area multi-line contact. Compared with the traditional single ramp, the contact stress is reduced by 70%, and the wear rate is reduced by an order of magnitude, significantly reducing contact stress and wear rate. At the same time, through high-precision fitting and the constant preload (usually 50-100N) applied by the return spring 71, all moving pairs are ensured to be in a pre-compressed "zero-backlash" state throughout the entire process, completely eliminating the influence of backlash on positioning accuracy. Actual measurements show that after 10,000 working cycles, the positioning accuracy decay is less than 0.001mm. These three factors work together to achieve an ultra-high centering accuracy of ±0.002mm, far exceeding that of traditional chucks (0.05mm level).

[0060] The principle behind automatic centering and force balance:

[0061] Paired opposing inclined planes and forced synchronization: The driving inclined planes corresponding to the radial sliding blocks 42 set in opposite directions are designed with opposite inclination angles. This allows the unidirectional rotation of the driving component 3 to force the two pairs of pawls 52 to move precisely and synchronously towards or away from each other, realizing the basic automatic centering function.

[0062] Adaptive locking and sequential centering: When a pair of jaws 52 contacts the workpiece first, their movement is hindered. This resistance causes the corresponding transmission chain to enter a mechanical self-locking state, but it is not absolutely rigidly locked. The torque of the drive component 3 is then transferred entirely to the transmission chain of the other pair of jaws 52, continuing to drive them forward until they contact the workpiece. This completely passive mechanical feedback process achieves "sequential centering" without manual intervention, completely solving the problem that traditional manual chucks cannot automatically center.

[0063] Automatic clamping force balancing: During the sequential centering process described above, the pushing force of the second pair of jaws 52 is transmitted through the workpiece to the already contacted first pair of jaws 52. The micro-elasticity of the return spring 71 behind the first pair of jaws 52 and the transmission chain allows for micron-level "elastic following" retraction. This causes the workpiece to "float" within a very small range until the contact reaction forces in the four directions automatically reach static equilibrium. This mechanism ensures that the difference in clamping force among the four jaws can be automatically controlled within ±5%, achieving automatic clamping force balancing, which is far superior to the ±30% or more of traditional chucks.

[0064] The principle behind clamping workpieces of arbitrary shape and preventing deformation of thin-walled parts:

[0065] Full-contour conformal clamping: Because each clamping unit 5 has an independent "adaptive locking" capability, when clamping irregular workpieces such as ellipses and polygons, each jaw 52 will stop independently the instant it contacts the workpiece contour. Therefore, the final position of the four jaws 52 can automatically adapt to the shape of the workpiece, forming an optimal envelope polygon, realizing full-contour conformal clamping of workpieces of any shape. The jaws 52 can be equipped with soft materials or floating structures to further diffuse contact stress and protect the workpiece surface.

[0066] Deformation-resistant design for thin-walled components:

[0067] Gradual loading: The "sequential centering" mechanism ensures that the clamping force is built up gradually and smoothly (usually within 0.5-1 seconds), rather than with an instantaneous impact, giving the workpiece material sufficient elastic response time and avoiding dynamic overshoot.

[0068] Minimizes pressure: Full-contour contact increases the effective contact area by more than 33% compared to traditional three-point contact. According to P=F / A, under the same clamping force F, the surface pressure P acting on the workpiece can be reduced to less than 1 / 4 of that of a traditional chuck, fundamentally preventing the crushing of thin-walled parts.

[0069] Precision micro-force control: Combined with a servo drive system, the rotation of the drive component 3 can provide 0.01mm-level motion feedback to the chuck 52, thereby achieving precise control over the final clamping force. This enables true "micro-force constant force clamping" when clamping thin-walled aluminum alloy, titanium alloy, or brittle materials, perfectly solving the deformation problem.

[0070] Clamping unit 5: Each clamping unit 5 includes a base jaw 51 and a chuck 52 mounted thereon via a T-nut. The chuck 52 can be replaced with a soft jaw or a special chuck depending on the shape of the workpiece.

[0071] Adaptive centering workflow:

[0072] Assume that the drive component 3 rotates counterclockwise, driving all the jaws 52 to move towards the center.

[0073] State A (Initial): All chucks 52 are in the retracted position.

[0074] State B (First pair of jaws 52 in contact): Due to the slightly elliptical shape of the workpiece, the first set of opposing jaws 52 first contact the two ends of the workpiece's long axis. At this time, the radial movement of the first set of jaws 52 is blocked by the workpiece, and the connected radial sliding block 42 and tangential transmission block 41 stop moving. The continued rotation of the upper pull ring 31 is "blocked" here.

[0075] State C (Adaptive Completion): However, the driving torque does not disappear; instead, it is entirely transferred to the second set of opposing tangential transmission blocks 41, which are still unobstructed. These blocks continue to slide, pushing the radial sliding blocks 42 and the jaws 52 towards the center until they closely conform to the contours of the workpiece's short axis. During this process, if the workpiece experiences slight displacement due to the clamping force, the first set of jaws 52, which have already made contact, will "automatically follow" and retract under the slight elastic deformation of the inclined plane pair. Ultimately, the four jaws uniformly conform to the elliptical contour of the workpiece, achieving perfect adaptive centering without over-positioning.

[0076] Reset mechanism: A reset spring 71 is provided on the radial sliding block 42 or the upper body 11. When the driving force is removed, all moving parts can automatically reset to the released state under the action of the spring force.

[0077] Industrial applicability

[0078] The high-precision self-centering clamping fixture provided by this invention can be widely used in various CNC lathes, machining centers, grinding machines, and precision measuring instruments. It is particularly suitable for manufacturing critical components in aerospace, automotive engine, and precision mold industries, where extremely high roundness and cylindricity requirements are needed, or where the components themselves are irregularly shaped and require precision machining. Its high precision, high stability, and self-adaptive capabilities can significantly improve machining quality, reduce scrap rates, and increase production efficiency.

[0079] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art should understand that modifications and equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications and substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A high-precision self-centering clamping fixture, comprising a base body (1), a plurality of clamping units (5) arranged circumferentially thereon, a central shaft (2), a driving component (3), and a decoupled driving mechanism (4), characterized in that, The central shaft (2) is rotatably supported at the center of the base body (1), and the clamping unit (5) is arranged circumferentially around the central shaft (2) and installed on the top of the base body (1); The decoupled drive mechanism (4) is installed inside the base body (1), and the decoupled drive mechanism (4) converts the rotational motion of the drive member (3) into the radial clamping motion of the clamping unit (5). The clamping unit (5) is driven to connect with the decoupled drive mechanism (4). The decoupled drive mechanism (4) is configured to allow any clamping unit (5) to continue radial movement when its radial movement is blocked during the continuous rotation of the drive member (3) until all clamping units (5) contact the workpiece contour, thereby realizing adaptive centering clamping of irregular workpieces.

2. The high-precision self-centering clamping fixture according to claim 1, characterized in that, The decoupled drive mechanism (4) includes a radial sliding block (42) and a tangential transmission block (41). The tangential transmission block (41) is connected to the central shaft (2). The tangential transmission block (41) is configured to slide tangentially along the central shaft (2) in response to the rotation of the drive member (3). The radial sliding block (42) is driven connected to the clamping unit (5) and slides radially along the central shaft (2). The tangential transmission block (41) and the radial sliding block (42) are connected by a mutually cooperating inclined structure, so that the tangential sliding of the tangential transmission block (41) can be converted into the radial movement of the radial sliding block (42).

3. The high-precision self-centering clamping fixture according to claim 2, characterized in that, The base body (1) includes an upper body (11) and a lower body (12). The upper body (11) and the lower body (12) are coaxially fixedly connected by a central shaft (2). A detachable dust cover (8) is also provided on the top of the central shaft (2). The dust cover (8) is fixed above the central hole of the upper body (11) by screws or buckles.

4. The high-precision self-centering clamping fixture according to claim 3, characterized in that, The driving component (3) includes an upper pull ring (31) and a lower pull ring (32). The upper pull ring (31) is coaxially sleeved on the outer periphery of the central shaft (2). The tangential transmission block (41) is connected to the outer periphery of the upper pull ring (31) by a pin, thereby driving the tangential transmission block (41) to slide tangentially. The lower pull ring (32) is coaxially sleeved on the inner periphery of the lower end of the central shaft (2), and both the upper pull ring (31) and the lower pull ring (32) rotate synchronously with the central shaft (2).

5. A high-precision self-centering clamping fixture according to claim 4, characterized in that, The drive component (3) is also equipped with a limiting component (6) for limiting the axial displacement of the pull ring. The limiting component (6) includes two separate arc-shaped limiting cards (61) and a pull-down fixing ring (62). The two limiting cards (61) are symmetrically attached to the top of the upper pull ring (31) and abut against the upper body (11) for limiting. The pull-down fixing ring (62) is sleeved on the bottom of the pull-down ring (32) and threaded to the central shaft (2) to realize the axial limiting of the pull-down ring (32).

6. A high-precision self-centering clamping fixture according to claim 2, characterized in that, There are multiple tangential transmission blocks (41) and radial sliding blocks (42), which are evenly distributed around the central axis (2) and linked with the upper pull ring (31). The inclined plane structures between at least two opposite tangential transmission blocks (41) and their respective corresponding radial sliding blocks (42) are arranged in opposite directions, so that the unidirectional rotation of the upper pull ring (31) can drive the synchronous opposite or back-to-back movement of the opposite clamping units (5).

7. A high-precision self-centering clamping fixture according to claim 6, characterized in that, The inclined structure includes an inclined protrusion (411) integrally formed on the outer side wall of the tangential transmission block (41). The two sides of the inclined protrusion (411) are wavy. The inner side wall of the radial sliding block (42) is provided with an inclined groove (421) that matches the inclined protrusion (411). The radial sliding block (42) achieves transmission connection with the tangential transmission block (41) through the meshing transmission of the inclined protrusion (411) and the inclined groove (421). The transmission direction is perpendicular to the sliding direction of the inclined protrusion (411), forming one of the motion components of the decoupled motion.

8. A high-precision self-centering clamping fixture according to claim 2, characterized in that, The clamping unit (5) consists of four sets, each driven by a set of four radial sliding blocks (42), and is arranged in pairs. The clamping unit (5) includes a base claw (51) mounted on the radial sliding block (42) and a chuck (52) mounted on the base claw (51). The driving force of the decoupled driving mechanism (4) acting on the base claw (51) is located at or near the radial force center of the base claw (51). The top of the radial sliding block (42) is integrally formed with an inclined block (422), and the bottom of the base claw (51) is provided with an inclined groove (511) that matches the inclined block (422). The base claw (51) slides and engages with the inclined block (422) and the inclined groove (511) to realize the detachable sliding connection of the radial sliding block (42). The sliding engagement direction is at a preset angle with the movement direction of the base claw (51) to form another motion component of the decoupled motion.

9. A high-precision self-centering clamping fixture according to claim 8, characterized in that, The radial sliding block (42) has a reset hole (423) on each of its two opposite sides. A reset component (7) for driving the radial sliding block (42) to reset is installed in the reset hole (423). The reset component (7) is connected to the upper body (11) to ensure that the radial sliding block (42) returns to its initial position after clamping.

10. A high-precision self-centering clamping fixture according to claim 9, characterized in that, The reset assembly (7) includes a reset spring (71) and a limiting bolt (72). The reset spring (71) is embedded in the reset hole (423). One end of the reset spring (71) abuts against the bottom of the reset hole (423), and the other end abuts against the upper body (11). The limiting bolt (72) passes through the upper body (11) and is threaded to the open end of the reset hole (423) to limit the axial displacement of the reset spring (71) and prevent the reset spring (71) from falling off.

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