Tensioning wheel multi-station self-adaptive pneumatic clamp

Abstract

This invention provides a multi-station adaptive pneumatic clamp with a tensioning wheel. It boasts high adaptive positioning accuracy, achieving an adaptive compensation range of ±0.5mm for positioning errors through BESO-optimized elastic positioning seats, reducing clamping deformation by 60%. It also features a wide vibration suppression bandwidth and fast response, specifically with a piezoelectric module response time ≤2ms, a vibration suppression bandwidth covering 50-2000Hz, and a 70% reduction in vibration amplitude. Furthermore, through five-station 72° phase difference collaborative control, the vibration amplitude of the substrate is reduced by 40-50% compared to a single-station clamp, rather than the mutual amplification of traditional solutions, achieving multi-station vibration cancellation. In addition, the system exhibits strong robustness: the online identification strategy for secondary paths adapts to changes in the dynamic characteristics of the clamp-workpiece system.

Description

Technical Field

[0001] This invention relates to the field of tensioner production equipment technology, specifically a multi-station adaptive pneumatic clamp for tensioners. Background Technology

[0002] For small, irregularly shaped workpieces with a central hole requiring precision machining, effectively securing the workpiece is a challenge, directly impacting its machining accuracy. Traditional clamps easily scratch the workpiece surface and are difficult to position precisely. Even slight errors in clamping position can lead to workpiece damage or deformation.

[0003] To address this, an existing patent for a multi-station fixture (patent number CN2021115718861) discloses a multi-station fixture, including a mounting plate and a lifting pressure plate. A connecting rod is fixedly connected to the middle of the mounting plate. The mounting plate has several processing grooves. A fixed clamping block is installed on one side of the processing groove, and a movable clamping block is installed on the other side. The fixed clamping block has a fixed clamping surface, and the movable clamping block has a movable clamping surface. The fixed clamping block is fixedly connected to the mounting plate. One end of the movable clamping block has a downward inclined surface. The middle of the lifting pressure plate has a movable hole through which the connecting rod passes. Several lower pressing blocks are installed on the lifting pressure plate. The lower end of each lower pressing block has an upward inclined surface. An adjusting plate is provided above the lifting pressure plate. The adjusting plate has a threaded hole through which the connecting rod passes. The connecting rod has an external thread.

[0004] However, when adopting the above technical solution, the applicant found the following defects: the structure is weak, there is a gap between the movable groove and the limiting strip, the workpiece drifts with the movable clamping block when clamped, the industrial applicability is limited and it is not conducive to experimental processing operations. Summary of the Invention

[0005] To address the limitations of existing technologies in actively suppressing cutting chatter over a wide frequency range (50-2000Hz), the present invention aims to provide a tensioning wheel multi-station adaptive pneumatic clamp.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a multi-station adaptive pneumatic clamp with a tensioning wheel, for clamping a base, comprising: The elastic positioning seat disposed within the clamping base is a hingeless elastic positioning seat based on a bidirectional progressive structure optimization design. It is integrally formed by additive manufacturing and utilizes the elasticity of material distribution to achieve adaptive positioning of the workpiece during the clamping process. Thin cylinder; the thin cylinder is connected to an air source through a proportional pressure regulating valve, the cylinder piston of the thin cylinder extends into the clamping base in its running direction, and an elastic pressure equalizing diaphragm is provided at the end of the cylinder piston and located in the clamping base to form a clamping device for limiting the workpiece with the clamping base. A piezoelectric active vibration suppression module is used to achieve broadband vibration suppression. It includes a piezoelectric ceramic stack embedded in the stress concentration area of ​​the clamping substrate. The stack is equipped with an accelerometer to collect cutting vibration signals in real time. The signals are then sent to a PID controller (i.e., a reverse drive signal calculated based on an improved filter-x least mean square algorithm, and a charge amplifier) ​​via a signal conditioning circuit. The PID controller dynamically outputs a compensation voltage to drive the deformation of the piezoelectric ceramic, thereby counteracting the main vibration mode. (The module has a response time ≤2ms and a vibration suppression frequency band covering 50–2000Hz). The multi-station collaborative control network includes a communication bus for synchronous data transmission, a main controller that establishes communication connections with each station via the communication bus and generates and distributes collaborative control instructions, and distributed slave stations located at each station for receiving instructions from the main controller and executing local control. The main controller has a built-in consistency protocol module to coordinate the cutting phase of each station. Specifically, the main controller dynamically adjusts the phase difference setpoint between the station and its adjacent stations based on the real-time vibration amplitude feedback from the PID controllers of each station, achieving a closed-loop linkage of macroscopic phase coordination and microscopic vibration suppression, so that adjacent stations maintain a 72° phase difference, thereby achieving spatial cancellation of flutter energy.

[0007] As a preferred embodiment of the present invention, the piezoelectric ceramic stack is made of PZT-8 or PZT-5H material, with 4-6 stacks arranged at each station and evenly distributed in a ring around the workpiece. The maximum displacement is 10μm, the stiffness is 200N / μm, the sampling frequency of the accelerometer is 10-20kHz, and the control cycle of the adaptive controller is 50-100μs.

[0008] As a preferred embodiment of the present invention, the clamping base is made of aluminum alloy material and has a topology-optimized reinforcing rib structure inside, and the direction of the reinforcing rib structure corresponds to the direction of the combined cutting force at each station.

[0009] As a preferred embodiment of the present invention, the elastic pressure equalizing diaphragm is made of polyurethane or rubber material, with a thickness of 1-3 mm and a mesh pattern on its surface.

[0010] As a preferred embodiment of the present invention, the iterative formula of the dynamic output compensation voltage algorithm of the PID controller is as follows: in, for The filter coefficient vector of the next iteration. is the step size factor and , for Error signal from the second sampling The signal is the reference signal after being filtered by the secondary path.

[0011] As a preferred embodiment of the present invention, the multi-station collaborative control network adopts differentiated rotation speed settings, so that adjacent stations maintain a constant 72° phase difference in the rotating coordinate system (so that the vibration vectors generated by each station cancel each other out).

[0012] As a preferred embodiment of the present invention, the formula for calculating the difference in the collaborative control is: , in, For the first Each workstation at any time The cutting phase angle is such that adjacent stations maintain a constant phase difference of 72°, or 2π / 5 radians.

[0013] As a preferred embodiment of the present invention, the secondary path of the dynamic output compensation voltage algorithm of the PID controller adopts an online identification strategy, and continuously updates the secondary path model coefficients using additional random noise signals to adapt to the changes in the dynamic characteristics of the fixture-workpiece system.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: High adaptive positioning accuracy: BESO's optimized elastic positioning seat enables adaptive compensation of positioning errors within a range of ±0.5mm, reducing clamping deformation by 60%; Wide vibration suppression bandwidth and fast response: The piezoelectric module has a response time of ≤2ms, a vibration suppression bandwidth covering 50-2000Hz, and reduces vibration amplitude by 70%; Multi-station vibration cancellation: Five stations with a 72° phase difference coordinated control reduce the vibration amplitude of the substrate by 40-50% compared to a single station, instead of the mutual amplification of traditional solutions; The system is highly robust: the online identification strategy for secondary paths adapts to changes in the dynamic characteristics of the fixture-workpiece system. Attached Figure Description

[0015] Other features, objects, and advantages of the invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a schematic diagram of the main structure of the present invention; Figure 2 This is a cross-sectional view of the thin cylinder and clamping module in this invention; Figure 3 This is a schematic diagram of the structure of the clamping base in this invention; Figure 4 This is a schematic diagram of the piezoelectric active vibration damping module layout of the present invention; Figure 5 This is a topology diagram of the multi-station collaborative control network in this invention.

[0016] In the figure: 1. Clamping base; 2. Elastic positioning seat; 3. Thin cylinder; 4. Proportional pressure regulating valve; 5. Air source; 6. Elastic pressure equalizing diaphragm; 7. Piezoelectric ceramic stack; 8. Accelerometer; 9. Communication bus; 10. Main controller; 11. Distributed slave station; 12. Pressure sensor; 13. Workpiece. Detailed Implementation

[0017] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0018] Example 1: BESO Optimized Design of Elastic Positioning Seat Step S1: Establish the initial design domain The positioning seat area within the clamping substrate is divided into finite element meshes. The upper limit of the material volume constraint is set to 30% of the initial volume, and the target elastic modulus is 0.1-0.3 times that of aluminum alloy, in order to achieve flexible positioning function.

[0019] Step S2: Two-way incremental optimization Iterative optimization using the BESO algorithm: Deletion strategy: Delete solid elements with element sensitivity below the threshold (sensitivity = strain energy density / material density) and convert them into voids; Enhancement strategy: Add elements to high-stress areas around voids to improve structural continuity; Convergence criterion: Stop iteration when the rate of change of the objective function (compliance minimization) is less than 0.1%.

[0020] Step S3: Additive Manufacturing The optimized structure was exported as an STL file and integrally formed using AlSi10Mg powder with selective laser melting (SLM) technology. After forming, it underwent heat treatment (T6 state) to eliminate residual stress and surface sandblasting.

[0021] Verification results: The elastic positioning seat has an elastic deformation capacity of 0.8mm in the radial direction, which can adaptively compensate for the tension wheel blank hole diameter error of ±0.5mm, and the positioning repeatability reaches ±0.01mm.

[0022] Example 2: Arrangement and Control of Piezoelectric Active Vibration Suppression Module Hardware configuration Piezoelectric ceramic stack: PZT-8 material from PICeramic is selected, with dimensions of 5×5×20mm. Four are arranged at each station, located at 0°, 90°, 180° and 270° around the workpiece, with an embedding depth of 5mm from the workpiece surface. Accelerometer: PCBPiezotronics 352C33, sensitivity 100mV / g, range ±50g, installed on the clamping base near the cutting point; Signal conditioning circuit: including a charge amplifier (adjustable gain) and a low-pass filter (cutoff frequency 5kHz); PID controller: based on TITMS320F28379D dual-core DSP, with a main frequency of 200MHz.

[0023] Control Algorithm Implementation The improved FxLMS algorithm is used, and the iterative formula is as follows: in: w(n) is the filter coefficient vector (length 64) for the nth iteration. μ is the step size factor, which takes a value of 0.001-0.01 and is adaptively adjusted according to the convergence speed. e(n) is the error signal (acceleration feedback) of the nth sampling. x′(n) is the signal after the reference signal is filtered by the secondary path.

[0024] Secondary Pathway Online Identification An additional random noise signal (amplitude 0.1V, frequency band 50-2000Hz) is continuously injected into the piezoelectric drive terminal, and the secondary path model coefficients are updated in real time using a system identification algorithm (RLS recursive least squares). It adapts to the dynamic characteristics of the fixture-workpiece system. The recognition cycle is 10ms, and the model order is 32.

[0025] Control effect: In the milling process of tension wheel groove (cutting speed 150m / min, cutting depth 2mm), the root mean square value of the vibration acceleration of the base body is 2.5g when the vibration suppression is not turned on, and it drops to 0.7g after the vibration suppression is turned on, with a vibration suppression efficiency of 72% and a response delay of 1.8ms.

[0026] Example 3: Five-station collaborative control network Network topology Employs EtherCAT industrial Ethernet, 1ms control cycle, and star topology connection. Main controller: Beckhoff CX2040, running TwinCAT3 real-time kernel; Distributed slave stations: 5 EL7211 servo drives, each controlling one of the 5 spindle stations; Synchronization mechanism: Distributed clock (DC) synchronization, jitter <1μs.

[0027] It is important to note that the relationship between the PID controller (piezoelectric active vibration damping module) and the main controller (multi-station collaborative control network) is as follows: the PID controller and the main controller are connected via a high-speed serial bus or an internal parallel bus, forming a two-layer control architecture. The PID controller, as the underlying execution controller, is deployed in the piezoelectric active vibration suppression module of each workstation and is dedicated to real-time vibration suppression control, with a control cycle of 50-100μs. The main controller, as the top-level coordinating controller, is deployed in the multi-station collaborative control network center and is dedicated to multi-station phase coordination and system scheduling, with a control cycle of 1ms. The main controller broadcasts system status information, including global clock synchronization signal, phase angle of adjacent workstations, and speed setpoint, to each PID controller via a bus. The PID controller uploads local vibration status information, including real-time acceleration amplitude, vibration suppression efficiency, and fault flag, to the main controller. In other words, the PID controller is integrated into the distributed slave station and communicates with the main controller via an internal bus. It receives phase coordination commands and feeds back the vibration suppression status. In fact, the PID controller mainly receives commands from the distributed slave station and runs the vibration suppression algorithm independently.

[0028] Phase Coordination Algorithm Formulas for calculating the cutting phase angle at each station: in: For the first The cutting phase angle of each workstation at time t; For the first Angular velocity (rad / s) of each workstation, with differentiated settings; For the initial phase offset, the workstation of .

[0029] Speed ​​Differentiation Settings To achieve a constant 72° phase difference, the rotational speeds at each station are set as follows: Consistency protocol implementation The master controller broadcasts a synchronization frame every 1ms, containing a global timestamp and phase reference. Each slave station adjusts its servo motor speed according to its local clock offset to ensure: Vibration cancellation verification When five stations process simultaneously, the vibration vectors generated by each station are distributed in a pentagonal shape in space, and the resultant vector is: (Theoretically, they completely cancel each other out, but in reality, there are residual values ​​due to amplitude deviation.) Actual test results: When the five stations are processed in a coordinated manner, the vibration amplitude of the clamped substrate is reduced by 45% compared with the single station processing and by 65% ​​compared with the five stations in the same phase synchronous processing.

[0030] Processing cycle sequence: A thin cylinder inflates in 0.0 seconds, and an elastic pressure-equalizing diaphragm clamps the workpiece. (Clamping force 500N, set via proportional pressure regulating valve) The clamping force stabilized in 0.2 seconds, and the pressure sensor indicated that it was OK. The servo motor starts in 0.3 seconds and accelerates to the target speed (300ms acceleration). S-curve acceleration and deceleration to avoid impact. The rotational speed stabilized in 0.6 seconds, phase locking was completed, and cutting began. The cutting process is completed in 3.0 seconds, and the motor decelerates to zero (deceleration takes 200ms). 3.2s cylinder exhaust, releasing the workpiece. The robotic arm retrieves the part in 3.5 seconds and proceeds to the next cycle. Example 4: Elastic pressure equalizing diaphragm design Material selection Made of polyurethane (PU) material with a Shore hardness of A80 and a thickness of 2mm, the surface is processed with a mesh pattern (groove width 0.5mm, groove depth 0.3mm, mesh spacing 2mm) to increase the coefficient of friction and allow gas to escape.

[0031] Performance parameters Clamping force range: 500-3000N (adjustable from 0-0.6MPa via proportional pressure regulating valve); Pressure distribution uniformity: >95% (tested using pressure-sensitive paper); Service life: >100,000 cycles.

[0032] Example 5: Clamping Matrix Topology Optimization Structural design The clamping base is made of 6061-T6 aluminum alloy, and the internal reinforcing rib structure was determined through topology optimization. Design goal: Maximize the first natural frequency (avoiding the cutting chatter frequency band); Constraint: The volume fraction of stiffeners is less than 20%; Optimization result: The direction of the reinforcing ribs is at an angle of ±15° to the direction of the combined cutting force at each station (determined by the cutting force direction angle analysis), forming a mesh support.

[0033] Performance improvement: The first natural frequency of the matrix is ​​increased from 420Hz to 680Hz after optimization, avoiding the regenerative chatter frequency band (400-600Hz) at commonly used cutting speeds.

[0034] Example 6: Comprehensive Performance Comparison and Verification To verify the inventiveness and technical effectiveness of this invention, a five-station tensioner machining experimental platform was built, and the following four schemes were used for comparative testing: Table 1 Experimental Details Test conditions are set uniformly: Workpiece: Automotive engine tensioner, material QT600-3, outer diameter φ120mm; Process: Combined machining of external diameter precision turning and slot milling; Cutting parameters: cutting speed =150m / min, feed rate =0.2mm / r, depth of cut =2mm; Environment: Temperature-controlled workshop 20±1℃, no external vibration isolation foundation. Table 2 Comparison of Positioning Accuracy and Clamping Deformation Creative Advantage: Solutions B and D, employing traditional rigid positioning seats, require grouping and matching of blanks (typically 5-6 groups), resulting in low clamping efficiency and over-positioning stress. This invention, through a BESO-optimized elastic positioning seat, maintains adaptive positioning capability while utilizing additive manufacturing to achieve a hingeless, integrated structure. This avoids the gap and wear problems of traditional elastic mechanisms, reducing clamping deformation by 68% and increasing efficiency by 3.75 times. Table 3 Comparison of vibration suppression performance (single-station test) Creativity is highlighted: Solution B (the current mainstream technology) relies solely on passive damping (rubber pads + mass blocks), which has no targeted vibration suppression capability in the 50-2000Hz wide frequency band, poor surface quality and short tool life. Although Scheme D introduces piezoelectric active vibration suppression, it uses the traditional FxLMS algorithm with fixed secondary path modeling. When the workpiece mass changes, the vibration suppression efficiency drops by more than 40%. This invention employs an improved FxLMS algorithm with online identification of secondary paths. By adding random noise signals to update the model coefficients in real time, even if the batch of workpieces changes (quality deviation ±10%), the vibration suppression efficiency remains >70%, and the response time is ≤2ms, which is 28% higher than that of scheme D. Table 4. Multi-station coordinated vibration cancellation effect (core creative achievement) Creativity Highlights – Fundamental Flaws of Existing Technologies: Existing technologies (Solutions B, C, and D) all employ a "synchronous phase" strategy, meaning that the rotational speed of each station is completely consistent (3000 rpm), attempting to achieve stability through synchronous control. However, due to factors such as mechanical transmission errors and differences in tool wear, the actual phase of each station exhibits random drift (±15°), causing vibration energy to be superimposed and amplified rather than canceled out. The vibration of a five-station machine tool is actually 85%-130% greater than that of a single-station machine tool, which is a long-standing industry problem for multi-station machine tools.

[0035] The disruptive solution of this invention: By employing a "phase-shifting coordination" strategy, differentiated rotational speed settings (3000 / 3060 / 3120 / 3180 / 3240 rpm) ensure that each station maintains a constant 72° phase difference in the rotating coordinate system, forming a stable pentagonal vibration vector distribution. Regardless of the presence of random disturbances, the vibration phase relationship of each station remains locked, the theoretical value of the synthesized vector is zero, and the measured base vibration is reduced by 45% compared to a single station, completely solving the problem of superposition and amplification of vibrations from multiple stations. Table 5 Comparison of Overall Processing Efficiency and Economy Table 6 Key Technological Innovations In summary, this invention, through a three-layer technical architecture of "adaptive positioning - active vibration suppression - phase coordination," achieves a leapfrog development in tensioner wheel processing, from single-station serial to multi-station parallel, from passive vibration reduction to active vibration suppression, and from vibration superposition to vibration cancellation. Compared with existing technologies: Innovative principle: For the first time, BESO topology optimization and additive manufacturing are combined for fixture positioning mechanisms, breaking through the lifespan bottleneck of traditional hinge elastic mechanisms; Algorithm-level innovation: Improved FxLMS algorithm introduces online identification of secondary paths to solve the time-varying adaptation problem of piezoelectric vibration suppression system; System-level innovation: Proposing a "phase-shifting collaborative" control strategy, overturning the traditional understanding of multi-station synchronous control, and achieving active spatial cancellation of vibration energy. Finally, it should be noted that the above 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 preferred embodiments, those skilled in the art should understand that modifications or 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 or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A multi-station adaptive pneumatic clamp for tensioning wheels, for clamping a base (1), characterized in that, include: The elastic positioning seat (2) is disposed in the clamping base (1); Thin cylinder (3); The thin cylinder (3) is connected to an air source (5) through a proportional pressure regulating valve (4). The cylinder piston of the thin cylinder (3) extends into the clamping base (1) in its running direction. An elastic pressure equalizing diaphragm (6) is also provided at the end of the cylinder piston and inside the clamping base (1) to form a clamping fastener for limiting the workpiece with the clamping base (1). The piezoelectric active vibration suppression module is used to achieve broadband vibration suppression, including: a piezoelectric ceramic stack (7), the piezoelectric ceramic stack is embedded in the stress concentration area of ​​the clamping substrate (1), and the cutting vibration signal is collected in real time by the provided acceleration sensor (8), and sent to the PID controller through the signal conditioning circuit. The PID controller dynamically outputs the compensation voltage to drive the piezoelectric ceramic deformation and reversely cancels the main vibration mode; The multi-station collaborative control network includes a communication bus (9) for achieving data synchronous transmission, a main controller (10) for generating and distributing collaborative control instructions by establishing communication connections with each station through the communication bus (9), and distributed slave stations (11) set at each station for receiving instructions from the main controller (10) and executing local control. The main controller has a built-in consistency protocol module to coordinate the cutting phase of each station, so that adjacent stations maintain a 72° phase difference, thereby achieving spatial cancellation of chatter energy.

2. The tensioning wheel multi-station adaptive pneumatic clamp as described in claim 1, characterized in that, The piezoelectric ceramic stack (7) is made of PZT-8 or PZT-5H material, with 4-6 stacks arranged at each station and evenly distributed in a ring around the workpiece, with a maximum displacement of 10μm.

3. The tensioning wheel multi-station adaptive pneumatic clamp as described in claim 1, characterized in that, The clamping base (1) is made of aluminum alloy and has a topology-optimized reinforcing rib structure inside. The direction of the reinforcing rib structure corresponds to the direction of the combined cutting force at each station.

4. The tensioning wheel multi-station adaptive pneumatic clamp as described in claim 1, characterized in that, The elastic pressure equalizing diaphragm (6) is made of polyurethane or rubber material, with a thickness of 1-3 mm and a mesh pattern on the surface.

5. A tensioning wheel multi-station adaptive pneumatic clamp as described in claim 1, characterized in that, The iterative formula for the dynamic output compensation voltage algorithm of the PID controller is as follows: in, for The filter coefficient vector of the next iteration. is the step size factor and , for Error signal from the second sampling The signal is the reference signal after being filtered by the secondary path.

6. A multi-station adaptive pneumatic clamp for tensioning wheels as described in claim 1, characterized in that, The multi-station collaborative control network adopts differentiated rotation speed settings, so that adjacent stations maintain a constant 72° phase difference in the rotating coordinate system.

7. A tensioning wheel multi-station adaptive pneumatic clamp as described in claim 6, characterized in that, The formula for calculating the difference in the collaborative control is: , in, For the first Each workstation at any time The cutting phase angle is maintained at 72° between adjacent stations. That is, a constant phase difference of 2π / 5 radians.

8. A tensioning wheel multi-station adaptive pneumatic clamp as described in claim 1, characterized in that, The secondary path of the dynamic output compensation voltage algorithm of the PID controller adopts an online identification strategy, which uses additional random noise signal to continuously update the coefficients of the secondary path model in order to adapt to the changes in the dynamic characteristics of the fixture-workpiece system.

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