A numerical control turning equipment for complex curved surface aluminum alloy workpiece

Abstract

The present application relates to the technical field of numerical control turning, in particular to a numerical control turning equipment for complex curved surface aluminum alloy workpiece, which comprises a rack, a drive box is arranged on one side of the top of the rack, a chuck is fixedly connected to the output end of the drive box, a plurality of clamping jaws are arranged on the chuck, an aluminum alloy workpiece is clamped on the chuck and the clamping jaws, an adjusting module is slidingly installed on a slide rail, and a turning tool is arranged on the adjusting module; a pressure partition assembly is arranged on one side of the plurality of clamping jaws; an auxiliary supporting assembly is slidingly installed on the slide rail; a control system comprises a pressure sensor, a displacement sensor, an acceleration sensor and a controller which are electrically connected to the pressure partition assembly and the auxiliary supporting assembly. Compared with the prior art, the pressure partition assembly cooperates with the pressure partition control strategy of the control system, which significantly improves the machining precision and consistency of thin-walled parts, avoids clamping damage to the surface of the workpiece, and realizes high-precision non-destructive clamping.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of numerical control turning, and in particular to a numerical control turning machining device for a complex curved surface aluminum alloy workpiece. BACKGROUND

[0002] As the core equipment of modern manufacturing industry, numerical control lathes are widely used in the precision machining of aluminum alloy workpieces. With the development of the fields of aerospace and precision optics, the demand for aluminum alloy workpieces with complex curved surfaces and thin-walled structures is increasing. Such workpieces usually have complex shapes, uneven wall thicknesses (for example Figure 11 At present, the clamping of such workpieces generally uses traditional three-jaw chucks or liquid plastic clamps.

[0003] In the prior art, the patent literature with the announcement number CN116140653A discloses an automatic clamping and fixing device for a lathe for aluminum alloy production. The automatic inner support fixing assembly movably arranged in the machining machine shell can fix and move the aluminum alloy shell, and can transport the shell to be machined. The cutting fluid in the upper end cutting fluid tank is sprayed out through the cutting fluid spray pipe, cools the machined aluminum alloy and shell, and washes away the excess waste, and then falls on the cutting fluid collection slope from the cutting fluid leakage groove, and is finally discharged from the cutting fluid outlet. However, like the traditional method, the traditional chuck applies uniform radial clamping force. For workpieces with uneven wall thicknesses, excessive deformation is prone to occur at the thin-walled part, which leads to the ovalization of the workpiece, uneven machining allowance, and finally affects the forming precision. Although the envelope type soft jaw can be used to improve the contact, it is still impossible to realize the precise distribution of pressure according to the change of wall thickness, and the clamping deformation problem cannot be fundamentally solved. In the machining process, the traditional equipment mainly relies on the passive methods of improving the rigidity of the workpiece and the tool and optimizing the cutting parameters to suppress vibration, which has limited effect and sacrifices the machining efficiency. Therefore, the application discloses a numerical control turning machining device for a complex curved surface aluminum alloy workpiece. SUMMARY

[0004] Therefore, the purpose of the application is to provide a numerical control turning machining device for a complex curved surface aluminum alloy workpiece to solve the problem of clamping deformation of thin-walled workpieces and low machining efficiency caused by the passive uniform clamping force and vibration suppression strategy of traditional equipment.

[0005] In order to achieve the above purpose, the application provides a numerical control turning equipment for complex curved surface aluminum alloy workpieces, which comprises a rack, a driving box arranged on one side of the top of the rack, a chuck fixedly connected to the output end of the driving box, a plurality of clamping jaws arranged on the chuck, an aluminum alloy workpiece clamped on the chuck and the clamping jaws, a self-centering adjusting bolt arranged on one side of the clamping jaws for driving the clamping jaws to clamp the aluminum alloy workpiece, a control panel arranged on one side of the driving box, a sliding rail arranged on the top surface of the rack, a tail end positioning frame arranged on the side of the sliding rail away from the driving box, an adjusting module slidingly installed on the sliding rail, and a turning tool arranged on the adjusting module.

[0006] A pressure partition assembly is arranged on one side of the clamping jaws, and the pressure partition assembly is used to actively adjust the positions with different wall thicknesses after the clamping jaws clamp the aluminum alloy workpiece.

[0007] An auxiliary supporting assembly is slidingly installed on the sliding rail, and the auxiliary supporting assembly is used to assist in supporting the tail part of the aluminum alloy workpiece and absorb and consume vibration energy.

[0008] A control system comprises a pressure sensor, a displacement sensor, an acceleration sensor and a controller electrically connected to the pressure partition assembly and the auxiliary supporting assembly, which is used to close-loop adjust the pressure distribution of the pressure partition assembly, real-time regulate and control the damping state of the end of the auxiliary supporting assembly, and realize synchronous control through the spindle speed signal and the tool position signal, so as to coordinate the overall turning stability and clamping consistency.

[0009] Preferably, the adjusting module comprises a first sliding frame horizontally slidingly installed on the sliding rail, which is used to drive the turning tool to move laterally on the sliding rail, a second sliding frame slidingly installed on the top of the first sliding frame, which is used to drive the turning tool to move longitudinally on the first sliding frame, an electric turntable rotationally installed on the top of the second sliding frame, which is used to drive the turning tool to adjust the angle, a tool clamping block slidingly installed on the electric turntable, which is used to drive the turning tool to make distance fine adjustment on the electric turntable, and the turning tool is arranged on the tool clamping block.

[0010] Preferably, the pressure partition assembly comprises a workpiece contact block arranged on one side of the clamping jaws, the workpiece contact blocks are all located at the inner ring position of the chuck, the workpiece contact block is hollowly arranged, an air bag is arranged in the workpiece contact block, a plurality of air injection holes are arranged on the surface of the chuck, an air inlet hole is arranged on one side of the air bag, the air inlet hole is in communication with the air injection hole, and a valve core is arranged at the mouth of the air injection hole.

[0011] Preferably, the workpiece contact block adopts NiTi-based shape memory alloy, has the characteristics of super-elastic deformation at room temperature and significant increase in rigidity when heated above the phase transition temperature, and can provide soft fitting and high rigidity locking states under different working conditions.

[0012] Preferably, the inner side of the workpiece contact block is provided with an SMA ring, which is pasted with a polyimide flexible electrothermal film or directly powered with a resistance heater, and has a NTC 10kΩ / thin film RTD temperature monitor inside.

[0013] Preferably, the auxiliary support assembly comprises a sliding seat slidingly installed on the slide rail, a top portion of the sliding seat is provided with an auxiliary support ring, a top portion of the auxiliary support ring is screwedly installed with a top limiting bolt, a bottom portion of the top limiting bolt is provided in a circular arc shape, a bottom portion of the auxiliary support ring is provided with a notch penetrating through an inside of the sliding seat, an inside of the sliding seat is provided with a mounting shell, a middle portion of the mounting shell is slidingly installed with a vertical sliding plate, a top portion of the vertical sliding plate penetrates through the notch of the sliding seat to the bottom portion of the auxiliary support ring, a top portion of the vertical sliding plate is rotatably installed with a first contact wheel, both sides of the mounting shell are rotatably installed with rotating plates, top surfaces of the rotating plates are rotatably installed with second contact wheels, a horizontal height of the second contact wheels is higher than that of the first contact wheels, when the auxiliary support assembly supports the tail portion of the aluminum alloy workpiece, the second contact wheels first contact the bottom portion of the aluminum alloy workpiece, one side of an outer surface of the vertical sliding plate is provided with a reset spring, one side of the reset spring is fixedly connected with the bottom portion of the mounting shell.

[0014] Preferably, middle portions of both sides of the vertical sliding plate are provided with passive trigger blocks, one side of the passive trigger blocks away from the vertical sliding plate is provided in a circular arc shape, bottom portions of the rotating plates are provided with active trigger blocks, one side of the active trigger blocks close to the passive trigger blocks is provided in a circular arc shape, when the second contact wheels are pressed by gravity of the aluminum alloy workpiece or are pushed downward by the aluminum alloy workpiece driven by the top limiting bolt, the two rotating plates move away from each other, the two active trigger blocks move close to each other, the vertical sliding plate and the first contact wheel synchronously descend to support and clamp the bottom portion of the aluminum alloy workpiece, when the aluminum alloy workpiece is processed, vibration generated by the aluminum alloy workpiece is consumed by the reset spring pressed by the vertical sliding plate.

[0015] Preferably, top portions of the vertical sliding plate and one side of top portions of the two rotating plates are provided with tuning vibration absorbers.

[0016] Preferably, the control system is configured with a frequency domain perception-based semi-active vibration suppression strategy, which is used for:

[0017] Real-time identification of a specific flutter frequency band by analyzing the vibration signal spectrum uploaded on the auxiliary support assembly;

[0018] When the frequency band vibration energy exceeds a preset threshold, a control instruction is generated and issued to the auxiliary support assembly;

[0019] Drive the actuator inside it, dynamically adjust the damping coefficient or inertial mass preload of the tuned vibration absorber, to realize the tracking and suppression of the machining flutter main frequency of the damping band.

[0020] Preferably, the control system is configured with a CAD mapping-based pressure zoning control strategy, which is used to:

[0021] Import the CAD model of the workpiece and extract the circumferential wall thickness distribution data of the clamping area;

[0022] According to the wall thickness distribution data, combined with the material mechanics characteristics, an optimized target clamping pressure distribution function is calculated;

[0023] Based on the function and receiving the feedback signal of the pressure sensor installed on the jaw or workpiece contact block, the independent pressure source connected to each air bag is closed-loop adjusted, so as to realize the adaptive and accurate distribution of clamping pressure.

[0024] The beneficial effects of the present application are:

[0025] 1. The numerical control turning machining equipment for complex curved surface aluminum alloy workpiece, by setting the pressure zoning assembly cooperating with the pressure zoning control strategy of the control system, the optimal pressure distribution is actively calculated based on the workpiece CAD model data, the shape memory alloy material workpiece contact block is flexibly fitted to the complex curved surface in the low temperature martensite phase state by independently controlling the pressure of each air bag, the stress-free "soft clamping" is realized, and after the phase change to austenite phase state by heating, the contact shape is rigidly locked, forming a high-precision customized clamp; The pressure sensor feedbacks data in real time during the machining process, the control system performs closed-loop fine tuning, and the optimal force field of "thick wall high pressure, thin wall low pressure" is continuously maintained, which fundamentally suppresses the clamping deformation and local collapse, significantly improves the machining precision and consistency of thin-walled parts, avoids workpiece surface damage, and realizes high-precision non-destructive clamping.

[0026] 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.

[0027] 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

[0028] 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.

[0029] Figure 1 This is a first-view three-dimensional structural diagram of the present invention;

[0030] Figure 2 This is a schematic diagram of the second-view three-dimensional structure of the present invention;

[0031] Figure 3 For the present invention Figure 2 Enlarged structural diagram at point A in the middle;

[0032] Figure 4 For the present invention Figure 2 Enlarged structural diagram at point B;

[0033] Figure 5 The auxiliary support assembly of the present application is shown in the partial structure diagram.

[0034] Figure 6 The clamping chuck and pressure partition assembly of the present application are shown in the structure diagram.

[0035] Figure 7 The auxiliary support assembly of the present application is shown in the partial structure diagram.

[0036] Figure 8 The auxiliary support assembly of the present application is shown in the partial structure diagram.

[0037] Figure 9 The auxiliary support assembly of the present application is shown in the partial structure diagram. Figure 8 The auxiliary support assembly of the present application is shown in the partial structure diagram.

[0038] Figure 10 The auxiliary support assembly of the present application is shown in the partial structure diagram.

[0039] Figure 11 The auxiliary support assembly of the present application is shown in the partial structure diagram.

[0040] The auxiliary support assembly of the present application is shown in the partial structure diagram.

[0041] 1, frame; 2, drive box; 3, control panel; 4, chuck; 5, jaw; 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 workpiece; 15, sliding seat; 16, auxiliary support ring; 17, top limiting bolt; 18, mounting shell; 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, gas injection hole; 27, air bag; 28, air inlet hole; 29, tuned vibration absorber; 30, return spring; 31, SMA ring. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical scheme and advantages of the present application more clear and explicit, the present application is further described in detail below in combination with specific embodiments.

[0043] It should be noted that the technical terms or scientific terms used in the present application shall be the usual meanings understood by those skilled in the art to which the present application belongs, unless otherwise defined. The terms "first", "second" and the like used in the present application do not represent any order, number or importance, but are only used to distinguish different components. The terms "including", "containing" and the like mean that the elements or objects before the terms cover the elements or objects listed after the terms and their equivalents, and do not exclude other elements or objects. The terms "connected" or "connected" and the like are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. The terms "up", "down", "left", "right" and the like are only used to represent relative positional relationships, which may change accordingly when the absolute position of the described object changes.

[0044] As shown in Figures 1 to 11 The numerical control turning machining equipment for complex curved surface aluminum alloy workpiece comprises a rack 1, a driving box 2 is arranged on one side of the top of the rack 1, a chuck 4 is fixedly connected to the output end of the driving box 2, a plurality of clamping jaws 5 are arranged on the chuck 4, the chuck 4 and the clamping jaws 5 clamp an aluminum alloy workpiece 14, a self-centering adjusting bolt 6 is arranged on one side of the clamping jaw 5, which is used to drive the plurality of clamping jaws 5 to clamp the aluminum alloy workpiece 14, a control panel 3 is arranged on one side of the driving box 2, a sliding rail 7 is arranged on the top surface of the rack 1, a tail end positioning frame 8 is arranged on the side of the sliding rail 7 away from the driving box 2, an adjusting module is slidingly installed on the sliding rail 7, and a turning tool 13 is arranged on the adjusting module; a pressure partition assembly is arranged on one side of the plurality of clamping jaws 5, which is used to actively adjust the positions with different wall thicknesses after the clamping jaws 5 clamp the aluminum alloy workpiece 14; an auxiliary supporting assembly is slidingly installed on the sliding rail 7, which is used to assist in supporting the tail part of the aluminum alloy workpiece 14 and absorb and consume vibration energy; a control system comprises a pressure sensor, a displacement sensor, an acceleration sensor and a controller which are electrically connected with the pressure partition assembly and the auxiliary supporting assembly, is used to close-loop adjust the pressure distribution of the pressure partition assembly, real-time control the damping state of the auxiliary supporting assembly, and realize synchronous control through the spindle speed signal and the tool position signal, so as to coordinate the overall turning stability and clamping consistency, wherein the adjusting module comprises a first sliding frame 9 which is horizontally slidingly installed on the sliding rail 7 and is used to drive the turning tool 13 to move horizontally on the sliding rail 7, a second sliding frame 10 is slidingly installed on the top of the first sliding frame 9 and is used to drive the turning tool 13 to move vertically on the first sliding frame 9, an electric turntable 11 is rotatably installed on the top of the second sliding frame 10 and is used to drive the turning tool 13 to adjust the angle, a tool clamping block 12 is slidingly installed on the electric turntable 11 and is used to drive the turning tool 13 to make distance fine adjustment on the electric turntable 11, and the turning tool 13 is arranged on the tool clamping block 12.

[0045] The complete process of the device starts from workpiece clamping and ends with machining completion, which is a highly integrated and intelligent closed-loop process. First, system initialization and workpiece clamping are performed: the operator places the complex curved aluminum alloy workpiece blank at the center of the chuck 4, starts the device, and the control system automatically calls the CAD model data of the workpiece to analyze the circumferential wall thickness distribution of the clamping area. Then, the control system calculates the optimal pressure distribution function P(θ) according to the wall thickness data, i.e., determines the clamping force required for each jaw 5 position. Then, the control system instructs the pressure partition assembly to start working, and the air bags 27 or micro-hydraulic cavities in each jaw 5 inflate or pressurize according to the instructions to drive the workpiece contact block 25 to adaptively fit the workpiece surface with different pressures, completing the initial intelligent clamping with minimal deformation. At the same time, the operator or automated system moves the auxiliary support assembly along the slide rail 7 to the overhanging position at the tail of the workpiece, and rotates the top limiting bolt 17 to make the circular arc at the top end gently contact the outer circle of the workpiece, completing the preliminary positioning.

[0046] Subsequently, the machining starts and real-time monitoring phase: after clamping is completed, the spindle drive box 2 is started, driving the workpiece to rotate, and 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 numerical control program, making the turning tool 13 contact the workpiece to start cutting. During the entire machining process, the multi-source sensor array starts continuous work: the pressure sensor installed on the jaw 5 continuously monitors 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 of the tail of the workpiece; the spindle encoder continuously feeds back the real-time speed and accurate phase angle of the spindle, and all these sensor data are transmitted to the central controller at high speed.

[0047] Then, the core closed-loop control and dynamic adjustment phase: 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 value of the pressure sensor with the target value based on the CAD model, dynamically adjusts the pressure of each air bag 27 through a closed-loop algorithm (such as PID), ensures the stability and optimization of the clamping force distribution, continuously counteracts the clamping deformation, on the other hand, the vibration control loop performs a fast Fourier transform (FFT) on the acceleration signal for frequency domain analysis, and once the vibration amplitude in the 300-1200Hz frequency band exceeds the safety threshold, it immediately generates a control command to drive the actuator (such as a micro servo motor or a magnetorheological fluid valve) in the auxiliary support assembly to adjust the damping state or mass pre-tightening of the tuned vibration absorber 29, so that its resonance peak accurately aligns with the current chatter main frequency, achieving dynamic vibration suppression. At the same time, the spindle phase control loop identifies when the spindle rotates to the "sensitive angle" of the thinnest wall thickness of the workpiece based on the encoder signal, and will instantaneously fine-tune the feed rate or superimpose a spindle speed modulation (SSV) signal to reduce the cutting force excitation at this point;

[0048] Finally, complete machining and workpiece removal: after the numerical control program is executed, the turning tool 13 retreats, the spindle stops rotating, the control system instructs the pressure partition assembly to release pressure, and the jaws 5 loosen the workpiece. The operator removes the auxiliary support assembly, and the completed workpiece can be removed. Thus, a high-precision machining process that integrates intelligent clamping, adaptive vibration suppression, and multi-variable collaborative control is completed.

[0049] As shown in Figures 6 to 11 The pressure partition assembly includes workpiece contact blocks 25 arranged on one side of the jaws 5. The workpiece contact blocks 25 are located at the inner circle position of the chuck 4. The workpiece contact blocks 25 are hollow. The workpiece contact blocks 25 have air bags 27 inside. The chuck 4 has gas injection holes 26 on its surface. The air bags 27 have gas inlet holes 28 on one side. The gas inlet holes 28 are connected to the gas injection holes 26. The gas injection holes 26 have valve cores at their mouths. The workpiece contact blocks 25 are made of NiTi-based shape memory alloy, which has the characteristics of superelastic deformation at room temperature and significantly improved stiffness above the phase transition temperature. It can provide two states of soft and high stiffness locking under different working conditions. The inner side of the workpiece contact blocks 25 is provided with an SMA ring 31. The SMA ring 31 is heated by a polyimide flexible electrothermal film or direct resistance heating, and the inside is buried with an NTC 10kΩ / thin film RTD temperature monitor.

[0050] The control system is configured with a pressure partition control strategy based on CAD mapping. This strategy is used to:

[0051] Import the CAD model of the workpiece and extract the circumferential wall thickness distribution data of the clamping area;

[0052] According to the wall thickness distribution data, combined with the material mechanics characteristics, an optimized target clamping pressure distribution function is calculated;

[0053] Based on the function and receiving the feedback signal of the pressure sensor installed on the jaw 5 or the workpiece contact block 25, the independent pressure source connected to each air bag 27 is closed-loop regulated to realize the adaptive and accurate distribution of the clamping pressure;

[0054] The operator imports the three-dimensional CAD model of the complex curved surface aluminum alloy workpiece to be processed into the control system through the control panel 3, the system automatically runs the algorithm, identifies and extracts the circumferential wall thickness distribution data of the clamping area of the workpiece by the jaw 5; then, the clamping and flexible fitting stage is entered, the operator puts the workpiece blank into the center of the chuck 4, preliminarily centers, starts the clamping program, and the control system calculates an optimal target clamping pressure distribution function P(θ) according to the aforementioned wall thickness data, combined with the elastic modulus and allowable stress of the material, through the built-in algorithm, the core principle is "higher pressure is distributed to thick wall area, lower pressure is distributed to thin wall area", then the control system instructs each independent micro-pump to fill different pressure gas into the corresponding air bag 27 through the air injection hole 26 and the valve core, the air bag 27 expands under pressure, and the workpiece contact block 25 made of NiTi-SMA material is deformed (the deformation state is fitted according to the curved surface of the workpiece, for example Figure 10the workpiece, complete the initial, low-stress "soft clamping"; then, phase transformation locking and rigidity conversion, after the completion of flexible fitting, the control system sends a command to the polyimide flexible electrothermal film wrapped or pasted on the SMA ring 31 to be powered and heated, or to 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 (such as 60℃), the NiTi-SMA occurs martensite to austenite phase change, its elastic modulus increases significantly, the yield strength improves, and it changes from a soft "playdough" state to a hard "steel block" state, permanently locking the perfect contact form formed by the previous adaptation, at this time, the workpiece contact block 25 is a high-rigidity precision clamp customized for the current workpiece, providing a solid reference for the next step of cutting; finally, enter the processing and real-time force control stage, the spindle starts, the turning begins, the pressure sensor installed on the chuck jaw 5 or the workpiece contact block 25 continuously feeds back the actual clamping force data of each point to the control system, and the control system compares these real-time data with the initially set target pressure distribution function P(θ), as soon as it is found that the pressure of a certain point deviates from the target value due to thermal deformation or vibration, etc., the corresponding proportional valve or air pump is immediately adjusted to realize the closed loop control of the pressure, this fine-tuning state is in the driving stop state or low speed state, and this dynamic adjustment process continues throughout the machining cycle, ensuring that the clamping force is always in the optimal distribution until the machining is completed, the system control electrothermal film is powered off and cooled, the SMA workpiece contact block 25 cools to room temperature and regains flexibility, the air bag 27 is depressurized, and the operator can easily remove the workpiece, and the workpiece surface is free of clamping marks;

[0055] To avoid continuous gas supply by rotary joint in the spindle rotation state, the preferred partition air bag 27 gas supply mode of the application is a pre-charged sealed retention structure, that is, after the workpiece is clamped and before the machining starts, each partition air bag 27 is inflated to the target pressure through an external pipeline, and then the external pipeline is disconnected, relying on the built-in valve core and sealing system to maintain the pressure during the whole machining process, without any rotating gas supply components;

[0056] Specifically, each partition air bag 27 is provided with an independent inflation interface, which adopts a standard valve core (for example, a Schrader valve core, that is, a "valve core") or a quick plug one-way interface with a valve core, and is provided with a metal sealing cap and an O-ring dust and oil seal outside the interface. The inflation interface is in communication with the corresponding partition air bag 27 through a micro air guide channel, and a micro flow limiting hole can be optionally arranged on the channel to improve the sealing stability and impact resistance. The inflation operation adopts a temporary connection of an external air source and a handheld inflation gun (or a hose assembly) with a precision pressure reducing valve / calibrated pressure gauge to the inflation interface of the target partition. After slow inflation and adjustment of the pressure to the set value according to the pressure gauge reading (or the partition built-in pressure sensor reading), the inflation gun is withdrawn, the sealing cap is tightened, and the closed state of the completely disconnected external air path is realized.

[0057] As shown in Figures 1 to 5 The auxiliary support assembly includes a sliding seat 15 slidingly installed on the sliding rail 7, the top of the sliding seat 15 is provided with an auxiliary support ring 16, the top of the auxiliary support ring 16 is screwedly installed with a top limiting bolt 17, the bottom of the top limiting bolt 17 is provided in a circular arc shape, the bottom of the auxiliary support ring 16 is provided with a slot opening through the inside of the sliding seat 15, the inside of the sliding seat 15 is provided with a mounting shell 18, the middle of the mounting shell 18 is slidingly installed with a vertical sliding plate 19, the top of the vertical sliding plate 19 penetrates the slot of the sliding seat 15 to the bottom of the auxiliary support ring 16, the top of the vertical sliding plate 19 is rotatably installed with a first contact wheel 20, both sides of the mounting shell 18 are rotatably installed with a rotating plate 22, the top surface of the rotating plate 22 is rotatably installed with a second contact wheel 23, 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, one side of the outer surface of the vertical sliding plate 19 is provided with a reset spring 30, one side of the reset spring 30 is fixedly connected with the bottom of the mounting shell 18, both sides of the middle of the vertical sliding plate 19 are provided with passive trigger blocks 21, and the side of the two passive trigger blocks 21 away from the vertical sliding plate 19 is provided in a circular arc shape, the bottom of the rotating plate 22 is provided with a driving trigger block 24, the side of the driving trigger block 24 close to the passive trigger block 21 is provided in a circular arc shape, when the second contact wheel 23 is pressed by the gravity of the aluminum alloy workpiece 14 or is pushed downward by the top limiting bolt 17 with the aluminum alloy workpiece 14, the two rotating plates 22 are away from each other, the two driving trigger blocks 24 are close to each other, the vertical sliding plate 19 and the first contact wheel 20 are synchronously lowered to support and clamp 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 reset spring 30 pressed by the vertical sliding plate 19;

[0058] The operator moves the tail end of the workpiece suspended on the chuck 4 to the upper side of the auxiliary support ring 16, and then manually rotates the top limiting bolt 17, so that the arc surface at the bottom of the top limiting bolt 17 slowly descends until it slightly contacts the top of the outer circle of the workpiece. The main purpose of this step is to preliminarily position the workpiece in the axial and radial directions, so as to prevent it from excessively sagging or deviating; then, the three-point clamping mechanism is triggered, and as the top limiting bolt 17 continues to descend or the workpiece sinks due to its own gravity and cutting force, the bottom of the workpiece will first contact and apply pressure to the two second contact wheels 23 with higher horizontal heights, which forces the two rotating plates 22 to rotate outward (away from each other) with the installation shaft as the center, and the active trigger block 24 at the bottom of the rotating plate 22 is displaced. 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 as arcs, the external movement is converted into an inward pressing force, which drives the vertical sliding plate 19 to overcome the pre-tightening force of the return spring 30 and slide downward along the guide rail of the installation housing 18. The first contact wheel 20 at the top of the vertical sliding plate 19 is lowered until it stably contacts and supports the bottom of the workpiece from below. At this time, the workpiece is evenly and stably clamped by the three contact wheels (one first contact wheel 20 supporting from below and two second contact wheels 23 supporting from the side and below), forming a perfect three-point centering clamping structure, and the top limiting bolt 17 limits from above to prevent the workpiece from jumping. Finally, the machining and vibration suppression stage is entered. When turning starts, the radial cutting force or vibration 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 part) begin to work. This system forms a mass-spring-damper model. The vibration energy forces the vertical sliding plate 19 to compress the return spring 30 to make a small amplitude reciprocating motion, thereby effectively suppressing and absorbing vibration, ensuring smooth cutting process until the machining is completed.

[0059] The top of the vertical sliding plate 19 and one side of the top of the two rotating plates 22 are provided with a tuned vibration absorber 29.

[0060] The control system is configured with a semi-active vibration suppression strategy based on frequency domain perception, which is used to:

[0061] By analyzing the vibration signal spectrum uploaded on the auxiliary support assembly, the specific chatter frequency band is identified in real time.

[0062] When the vibration energy of the frequency band exceeds the preset threshold, a control instruction is generated and sent to the auxiliary support assembly

[0063] Drive the internal actuator to dynamically adjust the damping coefficient or inertial mass pre-tightening amount of the tuned vibration absorber 29 to track and suppress the main frequency of the machining chatter in the vibration suppression frequency band.

[0064] The high-sensitivity acceleration sensor embedded inside the auxiliary support assembly (usually the vertical sliding plate 19 or the mounting housing 18) continuously collects the vibration signals transmitted by the workpiece at an extremely high sampling rate (usually kHz level), which contains a wealth of process system dynamic information; then enters the frequency domain analysis and diagnosis stage, the collected time domain vibration signals are transmitted to the fast signal processing unit of the control system in real time, which immediately performs fast Fourier transform (FFT) analysis on the signals, converting the time domain signals into frequency domain spectra, thus clearly showing the distribution of vibration energy at each frequency, the algorithm built-in the control system immediately scans this spectrum, accurately identifies which frequency component or components in the target frequency band of 300-1200Hz occupies the dominant position, and calculates its energy size; then is the intelligent decision and instruction generation stage, the control system compares the energy value of the dominant chatter frequency calculated with the preset safety threshold, once it is determined that the energy value exceeds the threshold (indicating that chatter is occurring or is about to become severe), the control algorithm will immediately calculate the target parameter required to achieve the best vibration suppression effect according to the current dominant frequency of the chatter (if adjusting the damping, the target parameter is the damping coefficient; if adjusting the mass block pre-tightening amount, the target parameter is the displacement or pre-tightening force), and generate the corresponding control instruction; finally is the precise execution and dynamic vibration suppression stage, the generated control instruction is instantly issued to the micro-execution mechanism integrated inside the auxiliary support assembly through the bus network, if the tuned absorber 29 is of the adjustable damping type (such as using magneto-rheological fluid, electro-rheological fluid or piezoelectric actuator), the instruction drives the execution mechanism to change the electric field or magnetic field strength of the damping medium, thereby adjusting the damping coefficient in real time and steplessly, if the tuned absorber 29 is of the adjustable mass block pre-tightening force type (such as using a micro-servo motor to drive a lead screw), the instruction drives the motor to rotate, changing the pre-tightening displacement of the mass block, thereby changing the natural frequency of the entire tuned absorber 29 system, the resonance peak of the adjusted tuned absorber 29 is precisely aimed at and covers the current monitored dominant chatter frequency, thereby absorbing and consuming the vibration of this frequency to the greatest extent like "aiming at the target".

[0065] It should be understood by those of ordinary skill in the art that the above discussion of any embodiment is only exemplary and is not intended to suggest that the scope (including claims) of the present application is limited to these examples; under the idea of the present application, 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 changes of different aspects of the present application as described above, which are not provided in detail for the sake of brevity.

[0066] The present application is intended to cover all such alternatives, modifications, and variations as fall within the broad scope of the appended claims. Accordingly, any and all such alternatives, modifications, equivalents, improvements and the like are intended to be encompassed by the present application.

Claims

1. A numerical control turning apparatus for a complex curved surface aluminum alloy workpiece, characterized by, The utility model relates to a kind of aluminum alloy machining center, including: Rack (1), the top side of the rack (1) is provided with drive box (2), the output end of the drive box (2) is fixedly connected with chuck (4), chuck (4) is provided with several clamping claws (5), chuck (4) is clamped with aluminum alloy workpiece (14) on clamping claw (5), the side of clamping claw (5) is provided with self-centering adjusting bolt (6), for driving several clamping claw (5) clamping aluminum alloy workpiece (14), one side of the drive box (2) is provided with control panel (3), the top surface of the rack (1) is provided with slide rail (7), the side of slide rail (7) away from the drive box (2) is provided with tail end positioning frame (8), adjusting module is slidably installed on slide rail (7), turning tool (13) is provided on the adjusting module; Pressure partition assembly, the pressure partition assembly is provided at the side of several clamping claws (5), and the pressure partition assembly is used to actively adjust the position of different wall thickness after the clamping claw (5) clamps the aluminum alloy workpiece (14); Auxiliary support assembly, the auxiliary support assembly is slidably installed on the slide rail (7), and the auxiliary support assembly is used to assist the tail of the aluminum alloy workpiece (14) Support and absorb and consume vibration energy; Control system, including pressure sensor, displacement sensor, acceleration sensor and controller electrically connected with the pressure partition assembly and the auxiliary support assembly, for closed-loop adjustment of the pressure distribution of the pressure partition assembly, real-time regulation and control of the damping state of the auxiliary support assembly end, and synchronous control is realized through spindle speed signal and tool position signal, so that overall turning stability and clamping consistency are coordinated; The pressure partition assembly includes workpiece contact block (25) provided at the side of several clamping claws (5), and several workpiece contact blocks (25) are located at the inner ring position of the chuck (4). The auxiliary support assembly comprises a sliding seat (15) slidingly mounted on the slide rail (7), a top portion of the sliding seat (15) is provided with an auxiliary support ring (16), a top portion of the auxiliary support ring (16) is screw-mounted with a top limiting bolt (17), a bottom portion of the top limiting bolt (17) is provided in an arc shape, a bottom portion of the auxiliary support ring (16) is provided with a notch penetrating through the inside of the sliding seat (15), the inside of the sliding seat (15) is provided with a mounting shell (18), a middle portion of the mounting shell (18) is slidingly mounted with a vertical sliding plate (19), a top portion of the vertical sliding plate (19) penetrates through the notch of the sliding seat (15) to the bottom portion of the auxiliary support ring (16), the top portion of the vertical sliding plate (19) is rotationally mounted with a first contact wheel (20), both sides of the mounting shell (18) are rotationally mounted with a rotating plate (22), the top surface of the rotating plate (22) is rotationally mounted with a second contact wheel (23), 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 portion of the aluminum alloy workpiece (14), the second contact wheel (23) first contacts the bottom portion of the aluminum alloy workpiece (14), one side of the vertical sliding plate (19) is provided with a reset spring (30), one side of the reset spring (30) is fixedly connected with the bottom portion of the mounting shell (18).

2. The apparatus for numerically controlled turning processing of a complex curved surface aluminum alloy workpiece according to claim 1, characterized in that, The adjusting module comprises a first sliding frame (9) horizontally slidingly mounted on the slide rail (7), used for driving the turning tool (13) to move laterally on the slide rail (7), a top portion of the first sliding frame (9) is slidingly mounted with a second sliding frame (10), used for driving the turning tool (13) to move longitudinally on the first sliding frame (9), a top portion of the second sliding frame (10) is rotationally mounted with an electric rotating disc (11), used for driving the turning tool (13) to be angle-adjusted, the electric rotating disc (11) is slidingly mounted with a tool clamping block (12), used for driving the turning tool (13) to be distance-adjusted on the electric rotating disc (11), the turning tool (13) is arranged on the tool clamping block (12).

3. The apparatus for numerically controlled turning processing of a complex curved surface aluminum alloy workpiece according to claim 1, characterized in that, The inner side of the workpiece contact block (25) is provided with an SMA ring (31), the SMA ring (31) is attached to a polyimide flexible electrothermal film or directly connected to an electric resistance heating, and an NTC 10kΩ / thin film RTD temperature monitor is buried inside.

4. The apparatus for numerically controlled turning processing of a complex curved surface aluminum alloy workpiece according to claim 1, characterized in that, The middle part of the vertical sliding plate (19) is provided with passive trigger blocks (21) on both sides, and the side of the two passive trigger blocks (21) away from the vertical sliding plate (19) is provided in a circular arc shape. The bottom of the rotating plate (22) is provided with a driving trigger block (24), and the side of the driving trigger block (24) close to the passive trigger block (21) is provided in a circular arc shape. When the second contact wheel (23) is pressed by the gravity of the aluminum alloy workpiece (14) or is driven by the top limiting bolt (17) to push the aluminum alloy workpiece (14) downward, the two rotating plates (22) move away from each other, the two driving trigger blocks (24) move close to each other, the vertical sliding plate (19) and the first contact wheel (20) descend synchronously, and the bottom of the aluminum alloy workpiece (14) is supported and clamped. When the aluminum alloy workpiece (14) is processed, the vibration generated by the aluminum alloy workpiece (14) is consumed by the reset spring (30) pressed by the vertical sliding plate (19).

5. The apparatus for numerically controlled turning processing of a complex curved surface aluminum alloy workpiece according to claim 3, characterized in that, The top of the vertical sliding plate (19) and one side of the top of the two rotating plates (22) are provided with a tuning vibration absorber (29).

6. The apparatus for numerically controlled turning processing of a complex curved surface aluminum alloy workpiece according to claim 5, characterized in that, The control system is configured with a semi-active vibration suppression strategy based on frequency domain perception, which is used to: Real-time identification of specific flutter frequency band by analyzing the vibration signal spectrum uploaded by the auxiliary support assembly; When the vibration energy of the frequency band exceeds the preset threshold, a control instruction is generated and sent to the auxiliary support assembly; Drive the internal actuator to dynamically adjust the damping coefficient or inertial mass preload of the tuning vibration absorber (29) to achieve tracking and suppression of the main frequency of the machining flutter.

7. The apparatus for numerically controlled turning processing of a complex curved surface aluminum alloy workpiece according to claim 3, characterized in that, The control system is configured with a pressure partition control strategy based on CAD mapping, which is used to: Import the CAD model of the workpiece and extract the circumferential wall thickness distribution data of the clamping area; According to the wall thickness distribution data, combined with the material mechanics characteristics, an optimized target clamping pressure distribution function is calculated; Based on the function and the feedback signal of the pressure sensor installed on the claw (5) or the workpiece contact block (25), the independent pressure source connected to each air bag (27) is closed-loop adjusted to realize self-adaptive and accurate distribution of the clamping pressure.

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