Self-locking ball positioning spline

Abstract

The utility model relates to mechanical drive technical field, especially a kind of self-locking positioning ball spline, including slide bar, sliding sleeve, self-locking positioning executor, position sensing module and control module, at least one load raceway extending along axial direction is provided on the outer circumferential surface of slide bar;Sliding sleeve is located on slide bar, the inner circumferential surface of sliding sleeve is provided with the ball circulation loop corresponding with load raceway, several balls are provided in ball circulation loop, so that sliding sleeve can low-friction slide along the axial direction of slide bar;Self-locking positioning executor is arranged on sliding sleeve, self-locking positioning executor is configured to receive locking instruction and exert mechanical force on slide bar, to generate static friction to prevent the relative movement between sliding sleeve and slide bar, realize self-locking positioning;The utility model is more stable and reliable in the occasion of vertical installation, bearing undirectional external force or intermittent work, avoids the security risk and precision loss caused by sliding or displacement.

Description

Technical Field

[0001] This utility model relates to the field of mechanical transmission technology, and in particular to a self-locking ball spline. Background Technology

[0002] Ball splines, as precision linear motion components, are widely used in automation equipment, CNC machine tools, industrial robots, and precision instruments. Their core function is to achieve high-precision, low-friction reciprocating motion along the axial direction. Traditional ball splines effectively reduce transmission resistance through the cooperation of sliding rods, sliding sleeves, and circulating balls, but they have significant limitations under certain working conditions.

[0003] Existing ball spline structures primarily rely on rolling friction to achieve sliding functionality and lack active locking capability. When the transmission system is subjected to radial or axial loads, equipment vibration, or is in a vertical installation state, the lack of effective constraint between the sleeve and the rod can lead to slight lateral movement or unexpected displacement, severely affecting the system's positioning accuracy and stability. Especially in applications with stringent positional requirements, such as high-precision assembly, optical focusing, and semiconductor processing, these minute displacements can result in decreased product yield or process failure.

[0004] To overcome the aforementioned shortcomings, existing technologies typically employ the addition of external brakes or locking devices, such as pneumatic / hydraulic brake calipers, electromagnetic brakes, or mechanical set screws installed on the outside of the sliding sleeve. While these solutions can achieve a certain locking effect, they have significant drawbacks: First, external brakes significantly increase the overall size and weight of the structure, altering the inertial characteristics of moving parts and hindering high-speed, lightweight design; second, the added components increase system complexity, making installation and debugging difficult and easily introducing assembly errors; third, braking response is delayed, making precise synchronization with motion control difficult; furthermore, the presence of external brakes may interfere with the layout of surrounding mechanisms, limiting their application in compact spaces. Utility Model Content

[0005] To solve the above problems, this utility model provides a self-locking ball spline that is more stable and reliable in situations such as vertical installation, exposure to unpredictable external forces, or intermittent operation, and avoids safety hazards and precision loss caused by slippage or displacement.

[0006] The technical solution adopted in this utility model is as follows: a self-locking ball spline, including a slide rod, a sliding sleeve, a self-locking actuator, a position sensing module, and a control module. The slide rod has at least one axially extending load raceway on its outer circumferential surface. The sliding sleeve is mounted on the slide rod, and its inner circumferential surface has a ball circulation loop corresponding to the load raceway. The ball circulation loop contains a plurality of balls, allowing the sliding sleeve to slide with low friction along the axial direction of the slide rod. The self-locking actuator is mounted on the sliding sleeve and is configured to receive a locking command and apply a mechanical force to the slide rod, thereby generating static friction to prevent relative movement between the sliding sleeve and the slide rod, achieving self-locking. The position sensing module is used to detect the absolute position or relative displacement of the sliding sleeve relative to the slide rod in real time. The control module is communicatively connected to the position sensing module and the self-locking actuator, and is configured to control the start and stop of the self-locking actuator based on the feedback signal from the position sensing module and a preset target position command.

[0007] A further improvement to the above scheme is that the self-locking actuator is a piezoelectric ceramic brake, which includes a brake block, a piezoelectric ceramic stack, and a preload application unit; the friction surface of the brake block is configured to contact or separate from the surface of the slide bar; the piezoelectric ceramic stack is connected to the brake block; and the preload application unit is used to provide an initial preload to the brake block.

[0008] The control module applies a driving voltage to the piezoelectric ceramic stack to control it to generate micro-displacement and drive the brake block to press or release the slide bar, thereby achieving high-frequency, high-precision intermittent braking or continuous locking self-locking positioning.

[0009] A further improvement to the above scheme is that the self-locking actuator is a pin-type locking mechanism, which includes a miniature linear motor, a locking pin, and an array of locking holes; the locking pin is driven by the miniature linear motor to move radially; the array of locking holes is arranged axially at equal or non-equal intervals on the surface or inside of the slide rod.

[0010] The control module controls the micro linear motor to drive the locking pin to insert or withdraw from the corresponding locking hole in the locking hole array, thereby achieving discrete position locking.

[0011] A further improvement to the above scheme is that the locking hole array is a blind hole array disposed inside the slide rod and parallel to the axis, the slide rod has a thinned wall thickness in the area corresponding to the blind hole array, and the locking pin achieves locking by compressing the thinned wall thickness area to generate elastic deformation when inserted.

[0012] A further improvement to the above solution is that the position sensing module is an absolute magnetic scale sensor, which includes a magnetic scale and a magnetic reading head. The magnetic scale is embedded or attached to the surface of the slide rod along the axial direction. The magnetic reading head is fixedly installed on the slide sleeve and is positioned relative to the magnetic scale at a preset gap for reading the absolute position signal.

[0013] A further improvement to the above scheme is that the position sensing module is an incremental grating ruler sensor, which includes a grating ruler, a reading head, and a zero-point calibration sensor; the grating ruler is axially disposed on the slide rod; the reading head is fixedly mounted on the sliding sleeve and is opposite to the grating ruler; the zero-point calibration sensor is disposed at the end of the sliding sleeve or the slide rod to provide a reference zero-point signal.

[0014] A further improvement to the above scheme is that it also includes a communication interface, which is connected to the control module and is used to receive target position commands, lock / unlock commands and control parameters sent by an external host computer, and to feed back the real-time position status and self-locking status to the host computer.

[0015] A further improvement to the above solution is that the control module has built-in positioning control logic, configured as follows:

[0016] Receive target location instructions;

[0017] Based on the feedback from the position sensing module, the external driving device is controlled to move the sliding sleeve to the vicinity of the target position;

[0018] Start the precise positioning program and control the sliding sleeve to make micro-movements until the position error is less than a preset threshold.

[0019] The self-locking actuator is triggered to perform a locking operation;

[0020] The precise positioning program is a closed-loop control program based on the PID control algorithm. The control module gradually reduces the position error by adjusting the control signal output to the external drive device.

[0021] The beneficial effects of this utility model are:

[0022] Compared to existing ball splines, this invention integrates a position sensing module and a control module, enabling real-time sensing of the precise position of the sliding sleeve. Based on preset commands, it drives a self-locking actuator to achieve rapid and reliable mechanical locking at the target position, completely eliminating the slight movement that may occur in traditional ball splines under load changes or vibration environments. This significantly improves positioning accuracy and repeatability, meeting the stringent requirements for positional stability in precision manufacturing, optical adjustment, and automated measurement. The control module can maintain smooth, low-friction sliding when movement is needed and lock instantly when positioning is required, improving the system's response speed and energy efficiency. Compared to traditional solutions requiring additional brakes, this invention features a compact structure and high integration, reducing installation space and overall weight. The self-locking function of this invention makes the ball spline more stable and reliable in vertical installations, under unpredictable external forces, or intermittent operation, avoiding safety hazards and accuracy loss due to slippage or displacement. It provides a key basic functional component for the innovative design of high-end equipment. Attached Figure Description

[0023] Figure 1 This is a three-dimensional schematic diagram of the self-locking ball spline of this utility model;

[0024] Figure 2 for Figure 1 A schematic diagram of one embodiment of a self-locking ball spline;

[0025] Figure 3 for Figure 1 A schematic diagram of one embodiment of a self-locking ball spline;

[0026] Figure 4 for Figure 1 A schematic diagram of one embodiment of a self-locking ball spline;

[0027] Figure 5 for Figure 1 A schematic diagram of one embodiment of a self-locking ball spline;

[0028] Figure 6 This is a connection diagram of the control system for a self-locking ball spline according to this utility model.

[0029] Figure 7 This is a flowchart illustrating the positioning method based on a control system according to this utility model.

[0030] Explanation of reference numerals in the attached drawings: 1. Slide bar; 11. Load raceway; 2. Slide sleeve; 21. Ball circulation loop; 3. Self-locking actuator; 31. Brake block; 32. Piezoelectric ceramic stack; 33. Preload application unit; 34. Micro linear motor; 35. Locking pin; 36. Locking hole array; 4. Position sensing module; 41. Magnetic grating ruler; 42. Magnetic reading head; 43. Optical grating ruler; 44. Reading head; 45. Zero point calibration sensor; 5. Control module; 6. Communication interface; 7. External drive device; 8. Host computer. Detailed Implementation

[0031] To facilitate understanding of this utility model, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of this utility model are shown in the drawings. However, this utility model can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this utility model.

[0032] It should be noted that when a component is said to be "fixed to" another component, it can be directly attached to the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Figures 1-5As shown, in one embodiment of this utility model, a self-locking ball spline is provided, including a slide rod 1, a sliding sleeve 2, a self-locking actuator 3, a position sensing module 4, and a control module 5. The outer circumferential surface of the slide rod 1 is provided with at least one axially extending load raceway 11. The sliding sleeve 2 is disposed on the slide rod 1, and the inner circumferential surface of the sliding sleeve 2 is provided with a ball circulation loop 21 corresponding to the load raceway 11. A plurality of balls are disposed in the ball circulation loop 21, allowing the sliding sleeve 2 to slide with low friction along the axial direction of the slide rod 1. The self-locking actuator 3 is disposed on the slide rod 1. On the sliding sleeve 2, the self-locking actuator 3 is configured to receive a locking command and apply a mechanical force to the sliding rod 1, thereby generating static friction to prevent relative movement between the sliding sleeve 2 and the sliding rod 1, achieving self-locking. The position sensing module 4 is used to detect the absolute position or relative displacement of the sliding sleeve 2 relative to the sliding rod 1 in real time. The control module 5 is communicatively connected to the position sensing module 4 and the self-locking actuator 3. The control module 5 is configured to control the start and stop of the self-locking actuator 3 based on the feedback signal from the position sensing module 4 and the preset target position command. This embodiment, by integrating the position sensing module 4 and the control module 5, can perceive the precise position of the sliding sleeve 2 in real time and drive the self-locking actuator 3 to achieve fast and reliable mechanical locking at the target position based on the preset command. This completely eliminates the slight movement that may occur in traditional ball splines under load changes or vibration environments, significantly improving positioning accuracy and repeatability, and meeting the stringent requirements for position stability in fields such as precision manufacturing, optical adjustment, and automated measurement. Control module 5 can maintain smooth, low-friction sliding when movement is needed, and lock instantly when positioning is required, improving the system's response speed and energy efficiency. Compared to traditional solutions requiring additional brakes, this invention features a compact structure and high integration, reducing installation space and overall weight. The self-locking function of this invention makes the ball spline more stable and reliable in vertical installations, under unpredictable external forces, or intermittent operation, avoiding safety hazards and precision loss caused by slippage or displacement. It provides a key basic functional component for the innovative design of high-end equipment.

[0034] The self-locking actuator 3 is a piezoelectric ceramic brake, which includes a brake block 31, a piezoelectric ceramic stack 32, and a preload application unit 33. The friction surface of the brake block 31 is configured to contact or separate from the surface of the slide bar 1. The piezoelectric ceramic stack 32 is connected to the brake block 31. The preload application unit 33 is used to provide an initial preload to the brake block 31. The control module 5 controls the piezoelectric ceramic stack 32 to generate micro-displacement by applying a driving voltage to it, thereby driving the brake block 31 to press or release the slide bar 1, thus achieving high-frequency, high-precision intermittent braking or continuous locking self-locking.

[0035] In this embodiment, the piezoelectric ceramic stack 32, through its inverse piezoelectric effect, can achieve nanometer-level micro-displacement actuation. Combined with the precise voltage regulation of the control module 5, the brake block 31 can apply extremely high-precision pressure to the slide rod 1, thereby achieving linear locking force control from millinewtons to hundreds of Newtons. The piezoelectric ceramic brake has microsecond-level response characteristics, supports high-frequency "point braking" locking and rapid release, and can achieve dynamic vibration suppression and real-time locking during the micro-adjustment of the sliding sleeve 2, effectively suppressing residual vibration of the system at the end of the positioning stage and improving stability efficiency. The preload application unit 33 provides initial preload to the system, ensuring that the brake block 31 and the slide rod 1 always maintain a controllable contact state, avoiding unnecessary friction during non-locking periods and eliminating the backlash and impact caused by gaps in traditional pneumatic or hydraulic braking.

[0036] The self-locking actuator 3 is a pin-type locking mechanism, which includes a miniature linear motor 34, a locking pin 35, and a locking hole array 36. The locking pin 35 is driven by the miniature linear motor 34 to move radially. The locking hole array 36 is arranged axially at equal or non-equal intervals on the surface or inside of the slide rod 1. The control module 5 controls the miniature linear motor 34 to drive the locking pin 35 to insert or withdraw from the corresponding locking hole in the locking hole array 36, thereby achieving discrete position locking. Specifically, the locking hole array 36 is a blind hole array arranged inside the slide rod 1 and parallel to the axis. The slide rod 1 has a thinned wall thickness in the area corresponding to the blind hole array. When the locking pin 35 is inserted, it generates elastic deformation by squeezing the thinned wall thickness area to achieve locking.

[0037] This embodiment achieves rigid locking of absolute position through the mechanical interlocking of the locking pin 35 and the high-precision locking hole array 36, completely eliminating the creep or slippage risks inherent in traditional friction braking. The locking reliability is extremely high, making it particularly suitable for applications requiring large lateral loads or long-term precision maintenance. The locking hole array 36 can be designed with equal or non-equal spacing as needed, balancing positioning flexibility with system rigidity and broadening its application range. Utilizing the elastic deformation zone formed by the localized thinning of the slide bar 1, the locking pin 35 can achieve interference fit and adaptive clamping upon insertion. This ensures both the robustness and gapless locking characteristic, while also absorbing some assembly and motion errors through elastic deformation, reducing the extreme dependence on the manufacturing precision of the locking pin and improving the system's tolerance and reliability.

[0038] The position sensing module 4 is an absolute magnetic scale sensor, which includes a magnetic scale 41 and a magnetic reading head 42. The magnetic scale 41 is axially embedded or attached to the surface of the slide rod 1; the magnetic reading head 42 is fixedly installed on the sliding sleeve 2 and maintains a preset gap relative to the magnetic scale 41 for reading absolute position signals. In this embodiment, the absolute coordinates of the sliding sleeve 2 can be obtained immediately upon system power-on, achieving precise positioning without the need for reference point homing, greatly shortening system preparation time and improving equipment operating efficiency and response speed. It is particularly suitable for operating conditions requiring frequent start-stop or rapid recovery after power failure. The magnetic scale 41 adopts a non-contact measurement principle, with no physical friction between the magnetic reading head 42 and the magnetic scale 41, avoiding the accuracy reduction and shortened lifespan problems caused by wear in traditional contact encoders, and possessing extremely high reliability and long-term stability. It has strong resistance to oil, dust, and vibration interference, making it suitable for harsh industrial environments.

[0039] The position sensing module 4 is an incremental grating ruler sensor, which includes a grating ruler 43, a reading head 44, and a zero-point calibration sensor 45. The grating ruler 43 is axially mounted on the slide rod 1. The reading head 44 is fixedly mounted on the sliding sleeve 2 and faces the grating ruler 43. The zero-point calibration sensor 45 is located at the end of the sliding sleeve 2 or the slide rod 1 and is used to provide a reference zero-point signal. In this embodiment, the incremental grating ruler 43 has extremely high resolution and measurement accuracy, and can achieve sub-micron level position feedback, providing a reliable data foundation for the precise displacement control and high-precision positioning and locking of the sliding sleeve 2, directly supporting the system to achieve nanometer-level repeatability positioning accuracy. By adding an independent zero-point calibration sensor 45, the system can quickly and accurately re-establish the position reference every time it is powered on or needed, effectively eliminating the problem of position information loss caused by power failure or abnormal interference, and taking into account the advantages of the high cost-effectiveness of incremental measurement and the reliability of absolute position reference.

[0040] It also includes a communication interface 6, which is connected to the control module 5. This interface receives target position commands, lock / unlock commands, and control parameters from an external host computer and provides real-time position and self-locking status feedback to the host computer. In this embodiment, bidirectional data interaction with an external host computer is achieved. It can efficiently receive target positions, locking commands, and parameter settings, while simultaneously providing real-time feedback on the axis's position and locking status. This establishes a seamless information flow between the device and system levels, providing a crucial interface for integrated, networked intelligent manufacturing systems and significantly enhancing the remote control and collaborative operation capabilities of the equipment.

[0041] Control module 5 has built-in positioning control logic, which is configured as follows:

[0042] Receive target location instructions;

[0043] Based on the feedback from the position sensing module 4, the external driving device is controlled to move the sliding sleeve 2 to the vicinity of the target position;

[0044] Start the precise positioning program and control the sliding sleeve 2 to perform micro-movements until the position error is less than a preset threshold.

[0045] The self-locking actuator 3 is triggered to perform a locking operation;

[0046] The precise positioning program is a closed-loop control program based on the PID control algorithm. The control module 5 gradually reduces the position error by adjusting the control signal output to the external drive device.

[0047] In this embodiment, a multi-stage control strategy of "coarse positioning - precise positioning - final locking" is adopted. First, the system rapidly approaches the target before initiating high-precision PID closed-loop fine-tuning, effectively balancing positioning efficiency and accuracy. This resolves the contradiction between overshoot and precision during high-speed motion, ultimately achieving micron-level high-precision repeatability positioning. The precise positioning program based on the PID algorithm can dynamically adjust the control signal output to the drive device, exhibiting strong robustness to nonlinear factors such as system friction and inertia. It can adaptively and gradually eliminate position deviations, ensuring that the sliding sleeve 2 reaches the target point stably and without overshoot, greatly improving the reliability and stability of the positioning process.

[0048] See Figures 1-6 As shown, a control system for a self-locking ball spline includes an external drive device 7 and a host computer 8. The external drive device 7 is drivenly connected to the sliding sleeve 2 and is used to provide power for it to move along the slide bar 1. The host computer 8 is connected to a communication interface 6 and is used to issue motion commands, monitor status, and set parameters.

[0049] The control module 5 coordinates and controls the external drive device 7 and the self-locking actuator 3 to jointly complete the high-precision positioning and self-locking tasks.

[0050] This embodiment utilizes control module 5 to perform coordinated intelligent control of high-precision position feedback, external drive device 7, and self-locking actuator, achieving a fully automated process from rapid coarse positioning and precise fine-tuning to final rigid locking. By deeply integrating discrete mechanical motion and locking actions into a coherent, precise, and reliable closed-loop process, it not only significantly improves the accuracy, efficiency, and consistency of the entire positioning system but also reduces reliance on external installation precision and operator skills. This achieves precise positioning and locking, making it particularly suitable for automated production lines and precision equipment requiring frequent repetitive positioning and high-precision maintenance.

[0051] See Figures 1-7As shown, a positioning method based on a control system includes the following steps: Step S1, initialization and zeroing: control the external drive device 7 to drive the sliding sleeve 2 to move until the position sensing module 4 triggers the zero-point calibration signal to establish a position coordinate system; Step S2, receiving target command: the control module 5 receives the target position command from the host computer 8 or an internally preset command through the communication interface 6; Step S3, coarse positioning and approach: the control module 5 controls the external drive device 7 to drive the sliding sleeve 2 to move at a relatively high speed to a first preset range near the target position; Step S4, precise positioning and fine adjustment: the control module 5 starts the precise positioning program, and based on the real-time high-precision position information fed back by the position sensing module 4, controls the external drive device 7 to slow down and make fine adjustments until the error between the actual position of the sliding sleeve 2 and the target position enters a second preset range, and the second preset range is smaller than the first preset range; Step S5, locking and confirmation: the control module 5 sends a locking command to the self-locking actuator 3, causing it to apply force to the slide rod 1 to lock the sliding sleeve 2 in the current position.

[0052] The position sensing module 4 detects the position information again. After confirming that no position shift has occurred during the locking process, the control module 5 sends a positioning and locking completion signal to the host computer 8 through the communication interface 6.

[0053] This embodiment employs a multi-level collaborative control system—coarse positioning, fine-tuning, locking, and verification—to automate a continuous process of high-precision positioning and reliable self-locking. Closed-loop feedback control dynamically compensates for transmission errors and environmental interference, ensuring extremely high final positioning accuracy and repeatability. Position confirmation is added after locking, effectively preventing minor displacements that might be caused by the locking action itself, thus achieving true zero-drift locking. This significantly improves the positional stability and reliability of precision equipment during long-term operation, reduces manual intervention, and increases production efficiency.

[0054] The above embodiments only illustrate several implementation methods of this utility model, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of this utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model patent should be determined by the appended claims.

Claims

1. A self-locking ball spline, characterized in that, include A slide bar, wherein at least one load raceway extending axially is provided on the outer circumferential surface of the slide bar; A sliding sleeve is provided on the sliding rod. The inner circumferential surface of the sliding sleeve is provided with a ball circulation loop corresponding to the load raceway. A plurality of balls are provided in the ball circulation loop so that the sliding sleeve can slide with low friction along the axial direction of the sliding rod. A self-locking actuator, disposed on the sliding sleeve, is configured to receive a locking command and apply a mechanical force to the slide rod, thereby generating static friction to prevent relative movement between the sliding sleeve and the slide rod, thus achieving self-locking; and A position sensing module is used to detect the absolute position or relative displacement of the sliding sleeve relative to the sliding rod in real time.

2. The self-locking ball spline according to claim 1, characterized in that, The self-locking actuator is a piezoelectric ceramic brake, which includes a brake block, a piezoelectric ceramic stack, and a preload application unit. The friction surface of the brake block is configured to contact or separate from the surface of the slide bar. The piezoelectric ceramic stack is connected to the brake block. The preload application unit is used to provide an initial preload to the brake block.

3. The self-locking ball spline according to claim 1, characterized in that, The self-locking actuator is a pin-type locking mechanism, which includes a miniature linear motor, a locking pin, and an array of locking holes. The locking pin is driven by the miniature linear motor to move radially. The array of locking holes is arranged axially at equal or non-equal intervals on the surface or inside of the slide rod.

4. The self-locking ball spline according to claim 3, characterized in that, The locking hole array is a blind hole array disposed inside the slide rod and parallel to the axis. The slide rod has a thinned wall thickness in the area corresponding to the blind hole array. When the locking pin is inserted, it generates elastic deformation by squeezing the thinned wall thickness area to achieve locking.

5. The self-locking ball spline according to claim 1, characterized in that, The position sensing module is an absolute magnetic scale sensor, which includes a magnetic scale and a magnetic reading head. The magnetic scale is embedded or attached to the surface of the slide rod along the axial direction. The magnetic reading head is fixedly installed on the slide sleeve and is positioned relative to the magnetic scale at a preset gap for reading the absolute position signal.

6. The self-locking ball spline according to claim 1, characterized in that, The position sensing module is an incremental grating ruler sensor, which includes a grating ruler, a reading head, and a zero-point calibration sensor. The grating ruler is axially mounted on the slide rod. The reading head is fixedly mounted on the sliding sleeve and is opposite to the grating ruler. The zero-point calibration sensor is located at the end of the sliding sleeve or the slide rod and is used to provide a reference zero-point signal.

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