Numerical control turning equipment for aluminum alloy workpiece with complex curved surface

Abstract

The invention relates to the technical field of numerical control turning, in particular to numerical control turning equipment for a complex curved surface aluminum alloy workpiece, which comprises a rack, a driving box is arranged on one side of the top of the rack, a chuck is fixedly connected to the output end of the driving box, a plurality of clamping jaws are arranged on the chuck, and an aluminum alloy workpiece is clamped on the chuck and the clamping jaws. An adjusting module is installed on the sliding rail in a sliding mode, and a turning tool is arranged on the adjusting module. The pressure partitioning assembly is arranged on one side of the multiple clamping jaws; the auxiliary supporting assembly is installed on the sliding rail in a sliding mode; the control system comprises a pressure sensor, a displacement sensor, an acceleration sensor and a controller which are electrically connected with the pressure partitioning assembly and the auxiliary supporting assembly. Compared with the prior art, through the pressure partition control strategy that the pressure partition assembly is arranged to be matched with the control system, the machining precision and consistency of the thin-wall workpiece are remarkably improved, meanwhile, the surface of the workpiece is prevented from being damaged by clamping, and high-precision lossless clamping is achieved.

Description

Technical Field

[0001] This invention relates to the field of CNC turning technology, and in particular to a CNC turning equipment for complex curved aluminum alloy workpieces. Background Technology

[0002] CNC lathes, as core equipment in modern manufacturing, are widely used for the precision machining of aluminum alloy workpieces. With the development of aerospace, precision optics, and other fields, the demand for aluminum alloy workpieces with complex curved surfaces and thin-walled structures is increasing. These workpieces typically have complex shapes and uneven wall thicknesses (e.g., Figure 11 Due to its characteristics such as poor rigidity, traditional three-jaw chucks or liquid plastic clamps are commonly used for clamping such workpieces.

[0003] In the prior art, Chinese patent document CN116140653A, concerning an automatically clamping and fixing lathe for aluminum alloy production, proposes an automatic internal support fixing assembly that moves within the machine housing to fix and move the aluminum alloy shell, enabling the transport of the shell to be processed. Meanwhile, cutting fluid from the upper cutting fluid tank is sprayed through a cutting fluid nozzle to cool the processed aluminum alloy and shell, flush away excess waste, and drain from the cutting fluid drain trough onto the cutting fluid collection ramp before being discharged from the cutting fluid outlet. However, consistent with traditional methods, the traditional clamping... The disc applies a uniform radial clamping force, which can easily cause excessive deformation at thin-walled sections of workpieces with uneven wall thickness, leading to ellipticization of the workpiece, uneven machining allowance, and ultimately affecting forming accuracy. Although enveloping soft jaws can be used to improve contact, it is still impossible to achieve precise pressure distribution for changes in wall thickness. The problem of clamping deformation has not been fundamentally solved. Furthermore, during the machining process, traditional equipment mainly relies on passive methods such as increasing the rigidity of the workpiece and tool and optimizing cutting parameters to suppress vibration. The effect is limited and it sacrifices machining efficiency. Therefore, this application discloses a CNC turning machining equipment for complex curved aluminum alloy workpieces. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a CNC turning machine for complex curved aluminum alloy workpieces, so as to solve the problem that traditional equipment, due to the use of uniform clamping force and passive vibration suppression strategy, causes thin-walled workpieces to be prone to clamping deformation and low processing efficiency.

[0005] To achieve the above objectives, the present invention provides a CNC turning machine for complex curved aluminum alloy workpieces, comprising a frame, a drive box disposed on one side of the top of the frame, a chuck fixedly connected to the output end of the drive box, a plurality of jaws disposed on the chuck, an aluminum alloy workpiece being clamped on the chuck and jaws, a self-centering adjusting bolt disposed on one side of the jaws for driving the jaws to clamp the aluminum alloy workpiece, a control panel disposed on one side of the drive box, a slide rail disposed on the top surface of the frame, a tail end positioning frame disposed on the side of the slide rail away from the drive box, an adjusting module slidably mounted on the slide rail, and a turning tool disposed on the adjusting module; A pressure partitioning component is disposed on one side of a plurality of jaws, and the pressure partitioning component is used to actively adjust the position of different wall thicknesses after the jaws clamp the aluminum alloy workpiece; An auxiliary support assembly is slidably mounted on the slide rail. The auxiliary support assembly is used to provide auxiliary support for the tail of the aluminum alloy workpiece and to absorb and dissipate vibration energy. The control system includes a pressure sensor, a displacement sensor, an acceleration sensor, and a controller electrically connected to the pressure partitioning component and the auxiliary support component. It is used to perform closed-loop adjustment of the pressure distribution of the pressure partitioning component, to adjust the damping state of the auxiliary support component in real time, and to achieve synchronous control through the spindle speed signal and the tool position signal, thereby coordinating the overall turning stability and clamping consistency.

[0006] Preferably, the adjustment module includes a first sliding frame horizontally slidably mounted on the slide rail for driving the turning tool to move laterally on the slide rail; a second sliding frame slidably mounted on the top of the first sliding frame for driving the turning tool to move longitudinally on the first sliding frame; an electric turntable rotatably mounted on the top of the second sliding frame for driving the turning tool to perform angle adjustment; a tool clamping block slidably mounted on the electric turntable for driving the turning tool to perform distance fine adjustment on the electric turntable; and the turning tool is disposed on the tool clamping block.

[0007] Preferably, the pressure zoning assembly includes workpiece contact blocks disposed on one side of a plurality of the jaws, the plurality of workpiece contact blocks being located on the inner ring of the chuck, the workpiece contact blocks being hollow, an air bladder being disposed inside the workpiece contact blocks, a plurality of air injection holes being disposed on the surface of the chuck, an air inlet being disposed on one side of the air bladder, the air inlet being connected to the air injection hole, and a valve core being disposed at the opening of the air injection hole.

[0008] Preferably, the workpiece contact block is made of NiTi-based shape memory alloy, which has the characteristics of being able to deform superelastically at room temperature and having its stiffness significantly improved when heated to above the phase transformation temperature, and can provide two states of compliant fit and high stiffness locking under different working conditions.

[0009] Preferably, an SMA ring is provided on the inner side of the workpiece contact block. The SMA ring is attached with a polyimide flexible electrothermal film or directly energized by resistance heating, and an NTC 10kΩ / thin film RTD is embedded inside for temperature monitoring.

[0010] Preferably, the auxiliary support assembly includes a sliding seat slidably mounted on the slide rail. An auxiliary support ring is provided at the top of the sliding seat. A top limiting bolt is threaded onto the top of the auxiliary support ring. The bottom of the top limiting bolt is arc-shaped. A slot penetrating the interior of the sliding seat is provided at the bottom of the auxiliary support ring. A mounting housing is provided inside the sliding seat. A vertical sliding plate is slidably mounted in the middle of the mounting housing. The top of the vertical sliding plate penetrates the slot of the sliding seat to the bottom of the auxiliary support ring. A first contact wheel is rotatably mounted on the top of the vertical sliding plate. Rotating plates are rotatably mounted on both sides of the mounting housing. A second contact wheel is rotatably mounted on the top surface of each rotating plate. The horizontal height of the second contact wheel is higher than that of the first contact wheel. When the auxiliary support assembly supports the tail of the aluminum alloy workpiece, the second contact wheel first contacts the bottom of the aluminum alloy workpiece. A return spring is provided on one outer surface of the vertical sliding plate, and one side of the return spring is fixedly connected to the bottom of the mounting housing.

[0011] Preferably, passive trigger blocks are provided on both sides of the middle of the vertical sliding plate, and the side of the two passive trigger blocks away from the vertical sliding plate is set in an arc shape. Active trigger blocks are provided at the bottom of the rotating plates, and the side of the active trigger blocks near the passive trigger blocks is set in an arc shape. When the second contact wheel is pressed by the gravity of the aluminum alloy workpiece or pushed downward by the top limiting bolt, the two rotating plates move away from each other, and the two active trigger blocks move closer to each other, driving the vertical sliding plate and the first contact wheel to descend synchronously, supporting and clamping the bottom of the aluminum alloy workpiece. When the aluminum alloy workpiece is being processed, the vibration generated by the aluminum alloy workpiece is consumed by the maximum damping limit of the vertical sliding plate.

[0012] Preferably, a tuned vibration absorber is provided on the top of the vertical sliding plate and on one side of the top of the two rotating plates.

[0013] Preferably, the control system is configured with a frequency-domain-aware semi-active vibration suppression strategy, which is used for: By analyzing the vibration signal spectrum uploaded by the auxiliary support component, specific flutter frequency bands can be identified in real time; When the vibration energy in this frequency band exceeds a preset threshold, a control command is generated and sent to the auxiliary support component; The internal actuator is driven to dynamically adjust the damping coefficient or inertial mass preload of the tuned vibration absorber in order to track and suppress the main frequency of machining chatter in the vibration suppression band.

[0014] Preferably, the control system is configured with a pressure zoning control strategy based on CAD mapping, which is used for: Import the workpiece CAD model and extract the circumferential wall thickness distribution data of the clamping area; Based on the wall thickness distribution data and the material mechanical properties, an optimized target clamping pressure distribution function is calculated. Based on this function and receiving feedback signals from pressure sensors installed on the jaws or workpiece contact blocks, closed-loop adjustment is performed on the independent pressure sources connected to each of the airbags, thereby achieving adaptive and precise distribution of clamping pressure.

[0015] The beneficial effects of this invention are: 1. This CNC turning equipment for complex curved aluminum alloy workpieces employs a pressure zoning control strategy with a pressure zoning component and control system. Based on the workpiece CAD model data, it actively calculates the optimal pressure distribution and independently controls the pressure of each air chamber. This allows the shape memory alloy workpiece contact block to flexibly conform to the complex curved surface in a low-temperature martensitic phase, achieving stress-free "soft clamping." After heating and phase transformation to the austenitic phase, the contact shape is rigidly locked, forming a high-precision customized fixture. During the machining process, pressure sensors provide real-time data feedback, and the control system performs closed-loop fine-tuning to continuously maintain the optimal force field of "high pressure for thick walls and low pressure for thin walls." This fundamentally suppresses clamping deformation and local collapse, significantly improving the machining accuracy and consistency of thin-walled parts, while avoiding workpiece surface damage and achieving high-precision, non-destructive clamping.

[0016] 2. This CNC turning equipment for complex curved aluminum alloy workpieces features an auxiliary support assembly. After initial positioning by the top limit bolts, the workpiece is pressed down, driving the rotating plates on both sides to flip outward. The arc trigger block pushes the vertical sliding plate downward, causing the three contact wheels to automatically grip the workpiece and achieve precise centering, eliminating fit clearance and ensuring high concentricity. The three-point closed support structure transforms the overhanging part of the workpiece into a simply supported beam structure, greatly enhancing local rigidity and effectively resisting tool deformation caused by radial cutting force, thus ensuring the geometric accuracy and dimensional stability of the workpiece. At the same time, the damping mechanism built into the vertical sliding plate constitutes a mass-spring-damping system, which can convert the energy of cutting vibration into heat dissipation, passively suppressing vibration and improving cutting stability and surface finish.

[0017] 3. This CNC turning equipment for complex curved aluminum alloy workpieces achieves intelligent tracking and suppression of cutting chatter by setting a tuned vibration absorber on the auxiliary support assembly and cooperating with the semi-active vibration suppression strategy of the control system. The embedded acceleration sensor collects vibration signals in real time, and after fast Fourier transform analysis by the control system, it accurately identifies the dominant chatter frequency and energy in the 300-1200Hz frequency band. When the threshold is exceeded, it immediately generates a command to drive the actuator to dynamically adjust the damping coefficient or mass preload of the tuned vibration absorber so that its resonance peak is aligned with and covers the current dominant chatter frequency in real time. This strategy upgrades the traditional passive vibration suppression to frequency domain sensing semi-active control, solves the limitation of fixed vibration suppression frequency, realizes adaptive tracking and precise suppression of wideband chatter, significantly widens the stable cutting zone, allows the use of more efficient cutting parameters, and forms an intelligent closed loop in conjunction with functions such as pressure zone control and spindle speed regulation, comprehensively improving the system's vibration resistance and machining limits. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only for this invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a first-view three-dimensional structural diagram of the present invention; Figure 2 This is a schematic diagram of the second-view three-dimensional structure of the present invention; Figure 3 For the present invention Figure 2 Enlarged structural diagram at point A in the middle; Figure 4 For the present invention Figure 2 Enlarged structural diagram at point B; Figure 5 This is a partial structural diagram of the auxiliary support component of the present invention; Figure 6 This is a schematic diagram of the clamping chuck and pressure partitioning component structure of the present invention; Figure 7 This is a partial structural diagram of the pressure zoning component of the present invention; Figure 8 This is a schematic diagram of the internal structure of the workpiece contact block of the present invention; Figure 9 For the present invention Figure 8 Enlarged structural diagram at point C; Figure 10 This is a schematic diagram of the deformation state of the workpiece contact block according to the present invention; Figure 11This is a schematic diagram of the thin-walled aluminum alloy workpiece with uneven wall thickness according to the present invention.

[0020] The diagram is marked as follows: 1. Frame; 2. Drive box; 3. Control panel; 4. Chuck; 5. Pallet; 6. Self-centering adjusting bolt; 7. Slide rail; 8. Tail end positioning frame; 9. First sliding frame; 10. Second sliding frame; 11. Electric turntable; 12. Tool clamping block; 13. Turning tool; 14. Aluminum alloy machined part; 15. Sliding seat; 16. Auxiliary support ring; 17. Top limit bolt; 18. Mounting housing; 19. Vertical sliding plate; 20. First contact wheel; 21. Passive trigger block; 22. Rotating plate; 23. Second contact wheel; 24. Active trigger block; 25. Workpiece contact block; 26. Air injection hole; 27. Airbag; 28. Air inlet; 29. ​​Tuned vibration damper; 30. Return spring; 31. SMA ring. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0022] It should be noted that, unless otherwise defined, the technical or scientific terms used in this invention should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0023] like Figures 1 to 11As shown, a CNC turning machine for complex curved aluminum alloy workpieces includes a frame 1, a drive box 2 on one side of the top of the frame 1, a chuck 4 fixedly connected to the output end of the drive box 2, a plurality of jaws 5 on the chuck 4, and an aluminum alloy workpiece 14 clamped on the chuck 4 and the jaws 5. A self-centering adjusting bolt 6 is provided on one side of the jaws 5 to drive the jaws 5 to clamp the aluminum alloy workpiece 14. A control panel 3 is provided on one side of the drive box 2. A slide rail 7 is provided on the top surface of the frame 1. A tail end positioning frame 8 is provided on the side of the slide rail 7 away from the drive box 2. An adjustment module is slidably installed on the slide rail 7, and a turning tool 13 is provided on the adjustment module. A pressure partitioning component is provided on one side of the jaws 5 and is used to actively adjust the position of the aluminum alloy workpiece 14 with different wall thicknesses after the jaws 5 clamp the aluminum alloy workpiece 14. An auxiliary support component is slidably installed on the slide rail 7 and is used to provide auxiliary support for the tail of the aluminum alloy workpiece 14 and absorb and dissipate heat. The system dissipates vibration energy; the control system includes pressure sensors, displacement sensors, acceleration sensors and controllers electrically connected to the pressure partitioning component and the auxiliary support component, used to perform closed-loop adjustment of the pressure distribution of the pressure partitioning component, to perform real-time control of the damping state at the end of the auxiliary support component, and to achieve synchronous control through the spindle speed signal and the tool position signal, thereby completing the coordination of overall turning stability and clamping consistency. The adjustment module includes a first sliding frame 9 horizontally slidably mounted on the slide rail 7, used to drive the turning tool 13 to move laterally on the slide rail 7. A second sliding frame 10 is slidably mounted on the top of the first sliding frame 9, used to drive the turning tool 13 to move longitudinally on the first sliding frame 9. An electric turntable 11 is rotatably mounted on the top of the second sliding frame 10, used to drive the turning tool 13 to perform angle adjustment. A tool clamping block 12 is slidably mounted on the electric turntable 11, used to drive the turning tool 13 to perform distance fine adjustment on the electric turntable 11. The turning tool 13 is set on the tool clamping block 12. The complete process of this equipment begins with workpiece clamping and ends with machining completion. It is a highly integrated and intelligent closed-loop process. First, the system is initialized and the workpiece is clamped: the operator places the complex curved aluminum alloy workpiece blank in the center of the chuck 4, starts the equipment, and the control system automatically calls the CAD model data of the workpiece to analyze the circumferential wall thickness distribution of its clamping area. Then, the control system calculates the optimal pressure distribution function P(θ) based on the wall thickness data, that is, determines the clamping force required to be applied to each jaw 5 position. Then, the control system instructs the pressure partitioning component to start working. The air bladder 27 or micro-hydraulic chamber in each jaw 5 is inflated or pressurized according to the instruction, driving the workpiece contact block 25 to adaptively conform to the workpiece curved surface with different pressures, completing the initial intelligent clamping with minimal deformation. At the same time, the operator or the automation system moves the auxiliary support component along the slide rail 7 to the workpiece tail overhang and shakes the top limit bolt 17 so that the arc surface at the top of it gently contacts the outer circle of the workpiece, completing the initial positioning. Subsequently, the machining start-up and real-time monitoring stage begins: After clamping, the spindle drive box 2 starts, driving the workpiece to rotate. The tool adjustment module (including the first sliding frame 9, the second sliding frame 10, the electric turntable 11, and the tool clamping block 12) moves according to the CNC program, causing the turning tool 13 to contact the workpiece and begin cutting. Throughout the machining process, the multi-source sensor array continues to work: the pressure sensor installed on the chuck 5 monitors in real time whether the actual clamping force at each point is consistent with the target value; the acceleration sensor installed in the auxiliary support assembly continuously collects the vibration signal at the tail of the workpiece; the spindle encoder continuously feeds back the real-time speed and precise phase angle of the spindle. All these sensor data are transmitted to the central controller at high speed. Then comes the core closed-loop control and dynamic adjustment stage: the central controller processes and analyzes the collected data in real time, and its control logic executes multiple tasks in parallel: on the one hand, the pressure control loop continuously compares the feedback values ​​of the pressure sensors with the target values ​​based on the CAD model, and dynamically adjusts the pressure of each airbag 27 through a closed-loop algorithm (such as PID) to ensure the stability and optimal distribution of clamping force and continuously resist clamping deformation; on the other hand, the vibration control loop performs a fast Fourier transform (FFT) on the acceleration signal and performs frequency domain analysis. Once a 300° vibration is detected... If the vibration amplitude in the -1200Hz frequency band exceeds the safety threshold, a control command is immediately generated to drive the actuator (such as a micro servo motor or magnetorheological valve) in the auxiliary support component to adjust the damping state or mass block preload of the tuned vibration absorber 29, so that its resonance peak is precisely aligned with the current chatter frequency, thereby achieving dynamic vibration suppression. At the same time, the spindle phase control circuit, based on the encoder signal, identifies when the spindle rotates to the "sensitive angle" where the workpiece wall thickness is thinnest, and will instantly fine-tune the feed rate or superimpose a spindle speed modulation (SSV) signal to reduce the cutting force excitation at this point. Finally, the machining and workpiece removal are completed: After the CNC program is executed, the turning tool 13 retracts, the spindle stops rotating, the control system commands the pressure zoning component to release pressure, causing the chuck 5 to release the workpiece, and the operator removes the auxiliary support component to remove the machined workpiece. Thus, a high-precision machining process integrating intelligent clamping, adaptive vibration suppression, and multi-variable collaborative control is completed.

[0024] like Figures 6 to 11 As shown, the pressure partition assembly includes workpiece contact blocks 25 disposed on one side of several jaws 5. The workpiece contact blocks 25 are all located in the inner ring of the chuck 4. The workpiece contact blocks 25 are hollow and have air bladders 27 inside. The surface of the chuck 4 is provided with several air injection holes 26. An air inlet 28 is provided on one side of the air bladder 27. The air inlet 28 is connected to the air injection holes 26. A valve core is provided at the opening of the air injection holes 26. The workpiece contact blocks 25 are made of NiTi-based shape memory alloy, which has the characteristics of being able to deform superelastically at room temperature and having significantly improved stiffness when heated to above the phase transition temperature. It can provide two states, namely compliant fit and high stiffness locking, under different working conditions. An SMA ring 31 is provided on the inner side of the workpiece contact block 25. The SMA ring 31 is attached with a polyimide flexible electric heating film or directly energized by resistance heating, and has an NTC 10kΩ / thin film RTD temperature monitoring embedded inside. The control system is configured with a pressure zoning control strategy based on CAD mapping, which is used for: Import the workpiece CAD model and extract the circumferential wall thickness distribution data of the clamping area; Based on the wall thickness distribution data and the mechanical properties of the material, an optimized target clamping pressure distribution function is calculated. Based on this function and receiving feedback signals from pressure sensors installed on the jaws 5 or workpiece contact blocks 25, the independent pressure sources connected to each airbag 27 are adjusted in a closed loop to achieve adaptive and precise distribution of clamping pressure. The operator imports the 3D CAD model of the complex curved aluminum alloy workpiece to be processed into the control system via the control panel 3. The system automatically runs an algorithm to identify and extract the circumferential wall thickness distribution data of the area where the workpiece is clamped by the jaws 5. Subsequently, the clamping and flexible fitting stage begins. The operator places the workpiece blank into the center of the chuck 4, performs preliminary alignment, and starts the clamping program. Based on the aforementioned wall thickness data, combined with the material's elastic modulus and allowable stress, the control system calculates an optimal target clamping pressure distribution function P(θ) using a built-in algorithm. The core principle is "higher pressure is allocated to thick-walled areas, and lower pressure is allocated to thin-walled areas." Then, the control system instructs the independent micro-pumps of each channel to inject gas at different pressures into the corresponding air bladders 27 through the air injection holes 26 and valve cores. The air bladders 27 expand under pressure, pushing the NiTi-SMA material workpiece contact block 25 to deform (the deformation state depends on the curved surface of the workpiece, for example...). Figure 10 As shown in the state diagram, since the SMA is at room temperature (below the austenitic phase transformation end temperature Af), it is in a low-modulus martensitic state, possessing excellent superelasticity and flexibility. Therefore, it can perfectly adapt to the irregular curved surface of the workpiece, completing the initial, low-stress "soft clamping". Then, phase transformation locking and rigidity conversion occur. After the flexible bonding is completed, the control system issues a command to energize and heat the polyimide flexible electrothermal film wrapped or pasted on the SMA ring 31, or directly apply current to the SMA ring 31 for resistance heating. At the same time, the built-in NTC thermistor or thin-film RTD temperature sensor monitors the SMA temperature in real time, forming a closed-loop temperature control. When the temperature is heated and stabilized above the Af temperature (e.g., 60℃), the NiTi-SMA undergoes a martensitic to austenitic phase transformation, its elastic modulus increases significantly, and its yield strength improves, transforming from a soft "playdough" state to a hard "steel block" state, permanently locking the previously adaptively formed perfect contact shape. At this point, The workpiece contact block 25 is a high-rigidity precision fixture tailored to the current workpiece, providing a solid reference for the next cutting step. Finally, the machining and real-time force control stage begins. The spindle starts, turning begins, and the pressure sensors installed on the chuck 5 or workpiece contact block 25 continuously feed back the actual clamping force data at each point to the control system. The control system compares these real-time data with the initially set target pressure distribution function P(θ). Once it is found that the pressure deviates from the target value at a certain point due to thermal deformation or vibration, it immediately makes a fine adjustment by adjusting the proportional valve or air pump of the corresponding air path to achieve closed-loop pressure control. This fine adjustment is performed when the drive is stopped or at low speed. This dynamic adjustment process continues throughout the entire machining cycle to ensure that the clamping force is always in the optimal distribution until the machining is completed. The system controls the electric heating film to be de-energized and cooled down. After the SMA workpiece contact block 25 cools to room temperature, it regains its flexibility, the airbag 27 is depressurized, and the operator can easily remove the workpiece without any clamping marks on the workpiece surface. To avoid continuous air supply using a rotary joint while the spindle is rotating, the preferred air supply method for the partitioned airbags 27 in this invention is a pre-filled sealed retention structure. That is, after the workpiece is clamped and before machining begins, each partitioned airbag 27 is inflated to the target pressure through an external pipeline. Then the external pipeline is disconnected, and the pressure is maintained throughout the machining process by relying on the built-in valve core and sealing system, without the need for any rotating air supply components. Specifically, each partition airbag 27 is equipped with an independent inflation port. The inflation port adopts a standard valve core (such as a Schrader valve core, also known as a "valve core") or a quick-connect one-way interface with a valve core. The interface is equipped with a metal sealing cap and an O-ring dustproof and oilproof seal on the outside. The inflation port is connected to the corresponding partition airbag 27 through a miniature air guide channel. A miniature flow limiting hole can be optionally provided on the channel to improve the sealing stability and impact resistance. The inflation operation uses an external air source and a handheld inflation gun (or hose assembly) with a precision pressure reducing valve / calibration pressure gauge to be temporarily connected to the inflation port of the target partition. Inflate slowly and adjust the pressure to the set value according to the pressure gauge reading (or the reading of the partition's built-in pressure sensor). Then, remove the inflation gun and tighten the sealing cap to achieve a completely closed state that disconnects the external air path.

[0025] like Figures 1 to 5 As shown, the auxiliary support assembly includes a sliding seat 15 slidably mounted on a slide rail 7. An auxiliary support ring 16 is provided on the top of the sliding seat 15. A top limiting bolt 17 is threaded onto the top of the auxiliary support ring 16. The bottom of the top limiting bolt 17 is arc-shaped. A slot penetrating the interior of the sliding seat 15 is opened at the bottom of the auxiliary support ring 16. A mounting housing 18 is provided inside the sliding seat 15. A vertical sliding plate 19 is slidably mounted in the middle of the mounting housing 18. The top of the vertical sliding plate 19 extends through the slot of the sliding seat 15 to the bottom of the auxiliary support ring 16. A first contact wheel 20 is rotatably mounted on the top of the vertical sliding plate 19. Rotating plates 22 are rotatably mounted on both sides of the mounting housing 18. Second contact wheels 23 are rotatably mounted on the top surface of each rotating plate 22. The horizontal height of the second contact wheel 23 is higher than that of the first contact wheel 20. When the auxiliary support assembly supports the tail of the aluminum alloy workpiece 14, the second contact wheel 23 contacts the aluminum alloy first. At the bottom of the workpiece 14, a return spring 30 is provided on one side of the outer surface of the vertical sliding plate 19. One side of the return spring 30 is fixedly connected to the bottom of the mounting housing 18. Passive trigger blocks 21 are provided on both sides of the middle of the vertical sliding plate 19, and the side of the two passive trigger blocks 21 away from the vertical sliding plate 19 is set in an arc shape. Active trigger blocks 24 are provided at the bottom of the rotating plate 22. The side of the active trigger blocks 24 close to the passive trigger blocks 21 is set in an arc shape. When the second contact wheel 23 is pressed by the gravity of the aluminum alloy workpiece 14 or pushed downward by the top limiting bolt 17, the two rotating plates 22 move away from each other, and the two active trigger blocks 24 move closer to each other, driving the vertical sliding plate 19 and the first contact wheel 20 to descend synchronously, supporting and clamping the bottom of the aluminum alloy workpiece 14. When the aluminum alloy workpiece 14 is processed, the vibration generated by the aluminum alloy workpiece 14 is consumed by the maximum damping limit of the vertical sliding plate 19. The operator moves the overhanging portion of the workpiece, which has been clamped at all four ends of the chuck, above the auxiliary support ring 16. Then, the operator manually rotates the top limiting bolt 17, causing its bottom arc surface to slowly descend until it makes slight contact with the top of the outer circle of the workpiece. The main purpose of this step is to perform preliminary axial and radial positioning of the workpiece to prevent it from sagging or shifting excessively. Subsequently, the three-point clamping mechanism is triggered. As the top limiting bolt 17 continues to descend or the workpiece sinks due to its own weight and cutting force, the bottom sides of the workpiece will first contact and apply pressure to the two second contact wheels 23, which are at a higher horizontal level. This pressure forces the two rotating plates 22 to rotate outward (in a direction away from each other) with their mounting axis as the center. The active trigger block 24 at the bottom of the rotating plate 22 is displaced accordingly. Since the contact surfaces of the active trigger block 24 and the passive trigger block 21 on the vertical sliding plate 19 are both precisely designed arc-shaped, this external motion is converted into an inward squeezing force, driving the vertical sliding plate 19 to overcome the preload of the return spring 30 and move along the mounting axis. The guide rail of the housing 18 slides downward, and the first contact wheel 20 at the top of the vertical sliding plate 19 descends accordingly until it steadily contacts and supports the bottom of the workpiece from below. At this time, the workpiece is evenly and stably held by three contact wheels (one first contact wheel 20 supporting from below and two second contact wheels 23 supporting from the side below), forming a perfect three-point centering clamping structure. The top limiting bolt 17 limits from above to prevent the workpiece from jumping. Finally, the machining and vibration damping stage begins. When turning begins, the radial cutting force or chatter generated by the workpiece is transmitted to the entire support mechanism through the three contact wheels. The vertical sliding plate 19 and its internal damping system (the return spring 30 is a component of it) begin to work. This system constitutes a mass-spring-damping model. The chatter energy forces the vertical sliding plate 19 to make a small reciprocating motion. Its damping mechanism converts mechanical kinetic energy into heat energy and dissipates it through friction or hydraulic means, thereby effectively suppressing and absorbing vibration, ensuring that the cutting process proceeds smoothly until the machining is completed. Tuned vibration absorbers 29 are provided on the top of the vertical sliding plate 19 and on one side of the top of the two rotating plates 22. The control system is equipped with a frequency-domain-aware semi-active vibration suppression strategy, which is used for: By analyzing the vibration signal spectrum uploaded by the auxiliary support components, specific flutter frequency bands can be identified in real time. When the vibration energy in this frequency band exceeds the preset threshold, a control command is generated and sent to the auxiliary support group. The internal actuator is driven to dynamically adjust the damping coefficient or inertial mass preload of the tuned vibration absorber 29 in order to track and suppress the main frequency of machining chatter in the vibration suppression band. A high-sensitivity accelerometer embedded within the auxiliary support assembly (typically a vertical sliding plate 19 or mounting housing 18) continuously acquires vibration signals transmitted from the workpiece at an extremely high sampling rate (typically at the kHz level). This signal contains rich dynamic information about the process system. Following this, the frequency domain analysis and diagnostic stage begins. The acquired time-domain vibration signal is transmitted in real-time to the control system's fast signal processing unit. This unit immediately performs Fast Fourier Transform (FFT) analysis on the signal, converting the time-domain signal into a frequency domain spectrum, clearly showing the distribution of vibration energy at various frequencies. The control system's built-in algorithm then scans this spectrum, accurately identifying which frequency component(s) dominate the amplitude within the target frequency band of 300-1200Hz and calculating its energy magnitude. Next comes the intelligent decision-making and command generation stage. The control system compares the calculated energy value of the dominant flutter frequency with a preset safety threshold. Once it determines that the energy value exceeds the threshold (indicating that flutter is occurring or about to become severe), the control algorithm immediately... Based on the current flutter frequency, the target parameters required to achieve the best vibration suppression effect are calculated (if adjusting damping, the target parameter is the damping coefficient; if adjusting mass preload, the target parameter is displacement or preload), and corresponding control commands are generated. Finally, in the precise execution and dynamic vibration suppression stage, the generated control commands are instantly sent to the integrated micro-actuator within the auxiliary support component via the bus network. If the tuned vibration absorber 29 is a damping-adjustable type (e.g., using magnetorheological fluid, electrorheological fluid, or piezoelectric actuator), the command drives... The actuator changes the electric or magnetic field strength of the damping medium, thereby adjusting the damping coefficient in real time and steplessly. If the tuned vibration absorber 29 is a mass block preload adjustable type (such as using a micro servo motor to drive the lead screw), the motor is commanded to rotate, changing the preload displacement of the mass block, thereby changing the natural frequency of the entire tuned vibration absorber 29 system. The resonance peak of the tuned vibration absorber 29 after adjustment is precisely aligned with and covers the currently monitored main flutter frequency, thus maximizing the energy absorption and consumption of the vibration at that frequency, just like "aiming at the bullseye".

[0026] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention (including the claims) is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in the details for the sake of brevity.

[0027] This invention is intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A CNC turning machine for complex curved aluminum alloy workpieces, characterized in that, include: A frame (1) is provided with a drive box (2) on one side of the top of the frame (1). A chuck (4) is fixedly connected to the output end of the drive box (2). A number of jaws (5) are provided on the chuck (4). An aluminum alloy workpiece (14) is clamped on the chuck (4) and the jaws (5). A self-centering adjusting bolt (6) is provided on one side of the jaws (5) to drive the jaws (5) to clamp the aluminum alloy workpiece (14). A control panel (3) is provided on one side of the drive box (2). A slide rail (7) is provided on the top surface of the frame (1). A tail end positioning frame (8) is provided on the side of the slide rail (7) away from the drive box (2). An adjustment module is slidably installed on the slide rail (7). A turning tool (13) is provided on the adjustment module. Pressure partitioning component, the pressure partitioning component is disposed on one side of a plurality of the jaws (5), the pressure partitioning component is used to actively adjust the position of different wall thicknesses after the jaws (5) clamp the aluminum alloy workpiece (14); An auxiliary support assembly is slidably mounted on the slide rail (7). The auxiliary support assembly is used to provide auxiliary support for the tail of the aluminum alloy workpiece (14) and to absorb and consume vibration energy. The control system includes a pressure sensor, a displacement sensor, an acceleration sensor, and a controller electrically connected to the pressure partitioning component and the auxiliary support component. It is used to perform closed-loop adjustment of the pressure distribution of the pressure partitioning component, to adjust the damping state of the auxiliary support component in real time, and to achieve synchronous control through the spindle speed signal and the tool position signal, thereby coordinating the overall turning stability and clamping consistency.

2. The CNC turning equipment for complex curved aluminum alloy workpieces according to claim 1, characterized in that, The adjustment module includes a first sliding frame (9) that is horizontally slidably mounted on the slide rail (7) for driving the turning tool (13) to move laterally on the slide rail (7). A second sliding frame (10) is slidably mounted on the top of the first sliding frame (9) for driving the turning tool (13) to move longitudinally on the first sliding frame (9). An electric turntable (11) is rotatably mounted on the top of the second sliding frame (10) for driving the turning tool (13) to perform angle adjustment. A tool clamping block (12) is slidably mounted on the electric turntable (11) for driving the turning tool (13) to perform distance fine adjustment on the electric turntable (11). The turning tool (13) is set on the tool clamping block (12).

3. The CNC turning equipment for complex curved aluminum alloy workpieces according to claim 1, characterized in that, The pressure zoning assembly includes workpiece contact blocks (25) disposed on one side of several of the jaws (5). The workpiece contact blocks (25) are all located in the inner ring of the chuck (4). The workpiece contact blocks (25) are hollow. An air bladder (27) is disposed inside the workpiece contact blocks (25). Several air injection holes (26) are disposed on the surface of the chuck (4). An air inlet (28) is disposed on one side of the air bladder (27). The air inlet (28) is connected to the air injection hole (26). A valve core is disposed at the opening of the air injection hole (26).

4. The CNC turning equipment for complex curved aluminum alloy workpieces according to claim 3, characterized in that, The workpiece contact block (25) is made of NiTi-based shape memory alloy, which has the characteristics of being able to deform superelastically at room temperature and having significantly improved stiffness when heated to above the phase transformation temperature. It can provide two states, namely compliant fit and high stiffness locking, under different working conditions.

5. The CNC turning equipment for complex curved aluminum alloy workpieces according to claim 4, characterized in that, The inner side of the workpiece contact block (25) is provided with an SMA ring (31), which is attached with a polyimide flexible electric heating film or directly energized by resistance heating, and has an NTC10kΩ / thin film RTD temperature monitoring embedded inside.

6. The CNC turning equipment for complex curved aluminum alloy workpieces according to claim 1, characterized in that, The auxiliary support assembly includes a sliding seat (15) slidably mounted on the slide rail (7). An auxiliary support ring (16) is provided at the top of the sliding seat (15). A top limiting bolt (17) is threaded onto the top of the auxiliary support ring (16). The bottom of the top limiting bolt (17) is arc-shaped. A slot is provided at the bottom of the auxiliary support ring (16) that penetrates the interior of the sliding seat (15). An installation housing (18) is provided inside the sliding seat (15). A vertical sliding plate (19) is slidably mounted in the middle of the installation housing (18). The top of the vertical sliding plate (19) penetrates the slot of the sliding seat (15) to the auxiliary support ring (16). At the bottom, a first contact wheel (20) is rotatably mounted on the top of the vertical sliding plate (19), and rotating plates (22) are rotatably mounted on both sides of the mounting housing (18). A second contact wheel (23) is rotatably mounted on the top surface of the rotating plate (22). The horizontal height of the second contact wheel (23) is higher than that of the first contact wheel (20). When the auxiliary support assembly supports the tail of the aluminum alloy workpiece (14), the second contact wheel (23) first contacts the bottom of the aluminum alloy workpiece (14). A return spring (30) is provided on one side of the outer surface of the vertical sliding plate (19). One side of the return spring (30) is fixedly connected to the bottom of the mounting housing (18).

7. The CNC turning equipment for complex curved aluminum alloy workpieces according to claim 6, characterized in that, Passive trigger blocks (21) are provided on both sides of the middle part of the vertical sliding plate (19), and the side of the two passive trigger blocks (21) away from the vertical sliding plate (19) is set in an arc shape. Active trigger blocks (24) are provided at the bottom of the rotating plate (22), and the side of the active trigger block (24) close to the passive trigger block (21) is set in an arc shape. When the second contact wheel (23) is pressed by the gravity of the aluminum alloy workpiece (14) or pushed downward by the top limiting bolt (17), the two rotating plates (22) move away from each other, and the two active trigger blocks (24) move closer to each other, driving the vertical sliding plate (19) and the first contact wheel (20) to descend synchronously, supporting and clamping the bottom of the aluminum alloy workpiece (14). When the aluminum alloy workpiece (14) is processed, the vibration generated by the aluminum alloy workpiece (14) is consumed by the maximum damping limit of the vertical sliding plate (19).

8. The CNC turning equipment for complex curved aluminum alloy workpieces according to claim 7, characterized in that, Tuned vibration absorbers (29) are provided on the top of the vertical sliding plate (19) and on one side of the top of the two rotating plates (22).

9. The CNC turning equipment for complex curved aluminum alloy workpieces according to claim 8, characterized in that, The control system is configured with a frequency-domain sensing-based semi-active vibration suppression strategy, which is used for: By analyzing the vibration signal spectrum uploaded by the auxiliary support component, specific flutter frequency bands can be identified in real time; When the vibration energy in this frequency band exceeds a preset threshold, a control command is generated and sent to the auxiliary support component; Drive the internal actuator to dynamically adjust the damping coefficient or inertial mass preload of the tuned vibration absorber (29) to achieve the tracking and suppression of the main frequency of processing chatter in the vibration suppression band.

10. The CNC turning equipment for complex curved aluminum alloy workpieces according to claim 5, characterized in that, The control system is configured with a pressure zoning control strategy based on CAD mapping, which is used for: Import the workpiece CAD model and extract the circumferential wall thickness distribution data of the clamping area; Based on the wall thickness distribution data and the material mechanical properties, an optimized target clamping pressure distribution function is calculated. Based on this function and receiving feedback signals from pressure sensors installed on the jaws (5) or workpiece contact blocks (25), closed-loop adjustment is performed on the independent pressure sources connected to each of the airbags (27), thereby achieving adaptive and precise distribution of clamping pressure.

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