Two-stage follow-up vibration suppression device and working method

Abstract

The invention provides a two-stage follow-up vibration suppression device and a working method. The two-stage follow-up vibration suppression device comprises a supporting head, a first-stage high-rigidity spring, a second-stage air cylinder supporting assembly and a ball bearing guide sleeve. The first-stage high-rigidity spring is connected with the supporting head and the second-stage air cylinder supporting assembly. The peripheral side of the supporting head is sleeved with the ball bearing guide sleeve. A composite vibration reduction system is formed through a series connection structure of the first-stage high-rigidity spring and the active adjustable second-stage air cylinder supporting assembly, the problem that the frequency application range of a single vibration reduction device is narrow is solved, precise guiding of the ball bearing guide sleeve is matched, and rapid absorption of high-frequency vibration and active compensation of low-frequency disturbance in the cutting process are achieved.

Description

Technical Field

[0001] This invention relates to the field of mirror milling support machining of thin-walled parts, specifically to a two-stage follow-up vibration suppression device and its working method. Background Technology

[0002] Large, thin-walled parts are characterized by their large size, thin wall thickness, and low rigidity, making them prone to chatter and deformation during machining. Traditional chemical milling methods for machining thin-walled parts suffer from low efficiency, high pollution, and low precision. Mirror milling, which has emerged in recent years, has become a new, green, efficient, and high-precision method for machining thin-walled parts, replacing chemical milling. Mirror milling uses synchronously moving machining heads and support heads on both sides of the workpiece to provide local support for the machining area of ​​the weakly rigid part during machining, reducing vibration and deformation and achieving high-efficiency and high-precision machining of thin-walled parts. Currently, most mirror milling follow-up support devices use solid supports, with contact with the workpiece being rolling or sliding. To suppress vibration and deformation of thin-walled parts, the support force cannot be too small; under large support forces, solid supports are prone to scratches or indentations on the workpiece surface. Current mirror milling support devices rarely actively suppress vibration by changing the dynamic characteristics of their own system, and their effectiveness in suppressing short-term vibrations caused by variable parameters such as variable speed and thickness cutting is weak.

[0003] Patent document CN206550656U discloses a fluid-driven auxiliary support device for machining thin-walled parts. This device supports the thin-walled part using a fluid-driven auxiliary support to reduce the impact of dynamic cutting forces on workpiece deformation. It suppresses thin-walled vibrations during the cutting process through fluid damping. This invention has advantages such as convenient follow-up of the support device, simple structure, no interference with cutting tools, easy control of the supporting force, and cooling and damping effects. However, the support device in the aforementioned patent document is fixed to the milling end, constrained by the machining space, and cannot support large thin-walled parts. This patent document uses a single fluid support, resulting in relatively small supporting force and weak rigidity. Its vibration suppression and deformation reduction effects are sometimes even inferior to solid support devices. Furthermore, this device lacks real-time measurement and active vibration suppression capabilities. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the purpose of this invention is to provide a two-stage follow-up vibration suppression device and its operating method.

[0005] A two-stage follow-up vibration suppression device according to the present invention includes: a support head, a first-stage high-stiffness spring, a second-stage cylinder support assembly, and a ball bearing guide sleeve; The primary high-stiffness spring connects the support head and the secondary cylinder support assembly; The ball bearing guide sleeve is fitted around the periphery of the support head.

[0006] Preferably, the support head is rigidly connected to a primary high-stiffness spring via a flange; The ball bearing guide sleeve is bolted to the machine tool base via a flange seat.

[0007] Preferably, the support head has a built-in vibration sensor array.

[0008] Preferably, the secondary cylinder support assembly includes: a dual-chamber air chamber, a piston rod, and a piezoelectric proportional valve; One end of the piston rod is connected to the piston head and is disposed in the dual-chamber air chamber. The air inlet and exhaust outlet of the dual-chamber air chamber are provided with piezoelectric proportional valves.

[0009] Preferably, the piston rod is connected to the primary high-stiffness spring via a transition plate.

[0010] Preferably, the ball guide bushing comprises: a cylindrical sleeve, circulating balls, and a self-lubricating bushing; The cylindrical sleeve is equipped with circulating balls and a self-lubricating bushing. The cylindrical sleeve is connected to the machine tool by interference fit or screws. The self-lubricating bushing is in contact with the piston rod surface.

[0011] Preferably, a partition is provided between the two chambers of the dual-chamber air chamber, and the partition is provided with flow-limiting holes.

[0012] Preferably, the primary high-stiffness spring is made of 60Si2MnA spring steel, and the spring stiffness of the primary high-stiffness spring is ≥1000N / mm.

[0013] Preferably, the dual-chamber air chamber is made of aluminum alloy, the volume ratio of the two chambers of the dual-chamber air chamber is 1:1.2, and the working pressure range of the dual-chamber air chamber is 0.2-1.5MPa.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. This application uses a combination of a support head, a primary high-rigidity spring, a secondary cylinder support assembly, and a ball bearing guide sleeve to improve vibration damping capability, thereby reducing the vibration amplitude during processing by ≥70%, improving the surface roughness Ra value by 50%-80%, and covering the common chatter frequency range of 0-8kHz.

[0015] 2. This application forms a composite vibration reduction system by connecting a primary high-stiffness spring and an actively adjustable secondary cylinder support assembly in series. This solves the problem of narrow frequency adaptation range of a single vibration reduction device. Combined with the precision guidance of the ball bearing guide sleeve, it achieves rapid absorption of high-frequency vibration and active compensation of low-frequency disturbance during the cutting process.

[0016] 3. This application adopts a composite guiding design of ball bearing guide sleeve and self-lubricating bushing, which overcomes the jamming phenomenon of traditional sliding pairs in high-frequency reciprocating motion, and enables the system damping ratio to be dynamically increased by 2-3 times, effectively suppressing cutting chatter and improving the surface quality of the machined parts. Attached Figure Description

[0017] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 Schematic diagram of a two-stage follower vibration suppression device The figure shows: support head 1, primary high-stiffness spring 2, secondary cylinder support assembly 3, and ball bearing guide sleeve 4. Detailed Implementation

[0018] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0019] Example 1 like Figure 1 As shown, this embodiment includes: a support head 1, a primary high-stiffness spring 2, a secondary cylinder support assembly 3, and a ball bearing guide sleeve 4. The primary high-stiffness spring 2 connects the support head 1 and the secondary cylinder support assembly 3. The ball bearing guide sleeve 4 is fitted around the periphery of the support head 1 to lubricate the movement. The support head 1 is rigidly connected to the primary high-stiffness spring 2 via a flange, and the ball bearing guide sleeve 4 is bolted to the machine tool base via a flange seat.

[0020] Specifically, The support head 1 has a built-in vibration sensor array that needs to detect vibration in real time. The support head 1 integrates a piezoelectric vibration sensor. The piston rod is connected to a high-stiffness spring 2 through a transition plate.

[0021] The secondary cylinder support assembly 3 includes: a dual-chamber air chamber, a piston rod, and a piezoelectric proportional valve; one end of the piston rod is connected to the piston head and is disposed in the dual-chamber air chamber, and the inlet and outlet of the dual-chamber air chamber are provided with piezoelectric proportional valves.

[0022] The ball guide sleeve 4 includes: a cylindrical sleeve, circulating balls, and a self-lubricating bushing; the cylindrical sleeve is equipped with circulating balls and a self-lubricating bushing, and the cylindrical sleeve is connected to the machine tool by an interference fit or screws. The self-lubricating bushing is in contact with the piston rod surface and can constrain the piston rod to move axially.

[0023] In this embodiment, the ball bearing guide sleeve 4 is an integrated, composite precision guiding mechanism, not a simple single component. Specific structure: External structure: It is a cylindrical sleeve whose outer cylindrical surface is precisely fixed to the cylinder or end cover of the machine tool by interference fit or screw fastening, which is its mounting base.

[0024] Internal upper structure: A circulating ball mechanism is integrated in the upper part or main working section of the inner hole of the ball guide sleeve 4. The circulating ball mechanism consists of raceways, circulating balls, and a reversing device, and its working principle is the same as or similar to that of a linear bearing.

[0025] Internal lower layer / matrix structure: Below the circulating ball layer, or serving as its matrix / shield, is a self-lubricating bushing. It is typically made of a high-performance engineering material (such as PTFE composite, graphite bronze, etc.) and comes into direct contact with the piston rod surface.

[0026] The circulating balls and the self-lubricating bushing are connected in series and physically integrated. This can be understood as follows: the self-lubricating bushing forms the inner wall matrix of the ball guide sleeve 4, while the circulating ball mechanism is embedded and penetrates the wall of the self-lubricating bushing. The piston rod first passes through the upper circulating balls and then slides within the lower self-lubricating bushing. The two are spatially connected, working together to support and guide the piston rod throughout its entire stroke. The inner bore of the ball guide sleeve 4 forms a precise dynamic fit with the piston rod. The circulating balls ensure smooth movement and extremely low friction; the self-lubricating bushing provides final guidance and damping.

[0027] In one embodiment, a partition is provided between the two chambers of the dual-chamber air chamber, and a flow-limiting orifice is provided on the partition.

[0028] In one embodiment, the primary high-stiffness spring 2 is made of 60Si2MnA spring steel, and the spring stiffness of the primary high-stiffness spring 2 is ≥1000N / mm.

[0029] In one embodiment, the dual-chamber air chamber is made of aluminum alloy, the volume ratio of the two chambers of the dual-chamber air chamber is 1:1.2, and the working pressure range of the dual-chamber air chamber is 0.2-1.5MPa.

[0030] This embodiment also provides a method for operating a two-stage follow-up vibration suppression device, including the following steps: Step S1: Preload the first-stage high-stiffness spring with an initial load of 2 to 200N; Step S2: During the cutting process, the vibration sensor array collects vibration acceleration signals in real time; Step S3: The control system separates the high-frequency component and triggers the compression / rebound of the first-stage high-stiffness spring 2, and simultaneously calculates the target value of the low-frequency compensation force. In step S4, the piezoelectric proportional valve adjusts the pressure difference between the two chambers of the dual-chamber air chamber to drive the piston rod to move, and the ball bearing guide sleeve 4 constrains the piston rod to move axially.

[0031] For step S3, its function is fully implemented by the digital control system through algorithms, and its process is as follows: Step 1: Signal Sensing A vibration sensor array (such as an accelerometer or dynamic force sensor) mounted on the support head 1 or piston rod acquires the raw vibration signal in real time. This vibration signal is a complex waveform of vibrations of various frequencies superimposed together, including both low-frequency contour following error and high-frequency cutting chatter.

[0032] Step 2: Digital Signal Processing The processor (such as DSP) in the control system performs a fast Fourier transform (FFT) on the acquired continuous analog signal.

[0033] The function of FFT is to convert a time-domain signal (amplitude-time) into a frequency-domain signal (amplitude-frequency). After the conversion, a spectrum is obtained, which can clearly show the distribution of vibration energy at different frequencies.

[0034] The "separation" is achieved by dividing the spectrum according to a preset frequency threshold (which is set based on the dynamic characteristics of the workpiece and the tool).

[0035] Low-frequency range: This is considered to be quasi-static or slowly changing contour errors, typically related to machine tool feed motion and large-scale workpiece surface changes. This part of the signal will be separated and used to control the pressure of the secondary cylinder support assembly 3 to achieve large-scale follow-up support.

[0036] High-frequency bands: These are considered harmful processing flutter (typically at frequencies of hundreds or even thousands of Hz), and these signals are the targets that need to be actively suppressed.

[0037] Step 3: Control Decision The system calculates the required counterforce to cancel out the separated high-frequency components based on their frequency and phase using a control algorithm (such as feedforward control based on an inverse model or an adaptive filtering algorithm). This decision is output as a control signal.

[0038] The compression / rebound of the primary high-stiffness spring 2 is triggered not by a "command" from the control system, but by a mechanical resonance response directly induced by the "external force" of high-frequency vibration components. The detailed process is as follows: After calculating the vibration suppression strategy, the control system drives the piezoelectric proportional valve to rapidly change the pressure difference between the two chambers of the secondary cylinder support assembly 3. This pressure difference pushes the piston rod to generate a high-frequency, low-amplitude active vibration suppression force. This force is applied to the workpiece through the support head, while its reaction force acts on the piston rod.

[0039] Example 2 Example 2 is a preferred example of Example 1.

[0040] like Figure 1 As shown, the main structure of this embodiment includes: Support head 1: rigidly connected to a first-stage high-stiffness spring 2 via a flange, with a built-in vibration sensor array.

[0041] First-stage high-stiffness spring 2: connected in series between support head 1 and transition base plate.

[0042] Secondary cylinder support assembly 3: includes a dual-chamber air chamber, piston rod and piezoelectric proportional valve.

[0043] Ball guide sleeve 4: The cylindrical sleeve contains circulating balls and a self-lubricating bushing.

[0044] When cutting vibration is transmitted through support head 1, the high-frequency component (>500Hz) is rapidly attenuated by the first-stage high-stiffness spring 2; the residual low-frequency vibration is counteracted by the reverse force generated by adjusting the pressure difference between the two chambers of the second-stage cylinder support assembly 3. The ball bearing guide sleeve 4 constrains the axial movement throughout the entire process to ensure the accuracy of the compensation force vector.

[0045] The primary vibration damping module includes a primary high-stiffness spring 2. Both ends of the primary high-stiffness spring 2 are fixed to the bottom of the support head 1 and the top of the secondary cylinder support assembly 3 via threaded connecting sleeves. The spring stiffness coefficient is 1000-1500 N / mm, the preload is set to 200±10 N, and the working stroke range is 0-5 mm. The primary high-stiffness spring 2 is made of 60Si2MnA spring steel, with a nitrided surface and a fatigue life ≥1×10⁻⁶. 7 Second-rate.

[0046] Secondary active compensation module: includes a dual-chamber air chamber and piston rod of secondary cylinder support assembly 3, which generates reverse compensation force through air pressure difference; The dual-chamber air chamber is made of cast aluminum alloy. The two chambers are separated by a partition. The working pressure range is 0.2-1.5MPa, the differential pressure response time is ≤10ms, and the maximum output compensation force is ≥1200N. The partition of the dual-chamber air chamber is equipped with a flow-limiting hole with a diameter of Φ2mm to balance sudden pressure shocks. The air chamber volume ratio is 1:1.2.

[0047] The piston rod, with a diameter of Φ25mm, is bolted to the transition plate at one end and extends into the air chamber at the other end, where it is rigidly fixed to the piston head. A piezoelectric proportional valve changes the gas flow rate by adjusting the current. It is installed at the gas inlet or outlet of the gas chamber, with a response time of ≤10ms and a maximum flow rate adjustment accuracy of ±0.5%. The ball guide sleeve 4 has built-in circulating balls and a self-lubricating bushing to constrain the piston rod's axial movement; the circulating balls have a diameter of Φ3mm and a tolerance grade of ≤IT5; the PTFE self-lubricating bushing has a thickness of 2mm and a surface roughness Ra≤0.2μm; the ball guide sleeve 4 is bolted to the machine tool base through a flange seat, and the coaxiality error between the axis of the ball guide sleeve 4 and the piston rod is ≤Φ0.01mm, and the axial clearance is ≤0.005mm.

[0048] Structural Relationships and Working Principles The support head 1 is flange-connected to a high-stiffness spring 2, which has an embedded vibration sensor array to collect XYZ three-dimensional vibration signals in real time. The high-stiffness spring 2 is connected in series between the support head 1 and the transition plate, with a stiffness coefficient ≥1000N / mm, and is used to attenuate high-frequency vibrations >500Hz within 5ms. The secondary cylinder support assembly 3: the dual-chamber air chamber is connected to the transition plate through a piston rod. The piezoelectric proportional valve adjusts the air pressure difference between the two chambers according to the control signal to generate a reverse compensation force with a phase difference of 180° from the low-frequency vibration. The ball guide sleeve 4: the built-in circulating balls and PTFE self-lubricating bushing have an axial movement accuracy error ≤±5μm, eliminating jamming caused by lateral load.

[0049] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0050] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A two-stage follow-up vibration suppression device, characterized in that, include: Support head (1), primary high-stiffness spring (2), secondary cylinder support assembly (3) and ball bearing guide sleeve (4); The first-stage high-stiffness spring (2) connects the support head (1) and the second-stage cylinder support assembly (3); The ball bearing guide sleeve (4) is fitted around the periphery of the support head (1).

2. The two-stage follow-up vibration suppression device according to claim 1, characterized in that: The support head (1) is rigidly connected to a primary high-stiffness spring (2) via a flange; The ball bearing guide sleeve (4) is bolted to the machine tool base via a flange seat.

3. The two-stage follow-up vibration suppression device according to claim 1, characterized in that: The support head (1) has a built-in vibration sensor array.

4. The two-stage follow-up vibration suppression device according to claim 3, characterized in that, The secondary cylinder support assembly (3) includes: a dual-chamber air chamber, a piston rod, and a piezoelectric proportional valve; One end of the piston rod is connected to the piston head and is disposed in the dual-chamber air chamber. The air inlet and exhaust outlet of the dual-chamber air chamber are provided with piezoelectric proportional valves.

5. The two-stage follow-up vibration suppression device according to claim 4, characterized in that: The piston rod is connected to the first-stage high-stiffness spring (2) via a transition plate.

6. The two-stage follow-up vibration suppression device according to claim 1, characterized in that, The ball guide sleeve (4) includes: a cylindrical sleeve, circulating balls and a self-lubricating bushing; The cylindrical sleeve is equipped with circulating balls and a self-lubricating bushing. The cylindrical sleeve is connected to the machine tool by interference fit or screws. The self-lubricating bushing is in contact with the piston rod surface.

7. The two-stage follow-up vibration suppression device according to claim 4, characterized in that: A partition is provided between the two chambers of the dual-chamber air chamber, and a flow-limiting hole is provided on the partition.

8. The two-stage follow-up vibration suppression device according to claim 1, characterized in that: The first-stage high-stiffness spring (2) is made of 60Si2MnA spring steel, and the spring stiffness of the first-stage high-stiffness spring (2) is ≥1000N / mm.

9. The two-stage follow-up vibration suppression device according to claim 4, characterized in that: The dual-chamber air chamber is made of aluminum alloy, the volume ratio of the two chambers of the dual-chamber air chamber is 1:1.2, and the working pressure range of the dual-chamber air chamber is 0.2-1.5MPa.

10. A method of operating the two-stage follow-up vibration suppression device according to any one of claims 4, characterized in that, Includes the following steps: Step S1, pre-tighten the first-stage high-stiffness spring (2) to an initial load of 200N; Step S2: During the cutting process, the vibration sensor array collects vibration acceleration signals in real time; Step S3: The control system separates the high-frequency component and triggers the compression / rebound of the first-stage high-stiffness spring (2), and simultaneously calculates the target value of the low-frequency compensation force. In step S4, the piezoelectric proportional valve adjusts the pressure difference between the two chambers of the dual-chamber air chamber to drive the piston rod to move, and the ball bearing guide sleeve (4) constrains the piston rod to move axially.

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