Damping tool structure based on local resonance cantilever beam oscillator and design method thereof

Abstract

The application discloses a damping cutter structure based on a local resonance cantilever beam oscillator and a design method thereof. The damping cutter structure comprises a cutter rod, a fixing ring and a circular oscillator which are sleeved on the cutter rod. The fixing ring is used for fixing the circular oscillator on the cutter rod. The fixing ring and the cutter rod are detachably connected. The fixing ring and the circular oscillator are connected through bolts and nuts. The circular oscillator is used for absorbing the vibration of the cutter rod. The first-order natural frequency of the cutter is obtained. The cantilever beam oscillator is designed by taking the frequency as a design target and the actual cutter space size as a limiting condition. The first-order bending mode frequency of the cantilever beam oscillator under the fixed boundary condition is calculated and determined through a finite element method, so that the first-order natural frequency of the cutter is consistent. A theoretical model of the damping cutter is established by using a spectral element method, and the vibration suppression frequency range of the damping cutter is determined. The size of the oscillator can be adjusted to realize the adjustment of the vibration suppression frequency range of the damping cutter system, and the problem that the vibration suppression frequency range of the traditional passive vibration suppression structure is narrow and cannot be adjusted in real time is avoided.

Description

Technical Field

[0001] This invention belongs to the field of tool design, and in particular relates to a vibration reduction tool structure and its design method based on a local resonant cantilever beam oscillator. Background Technology

[0002] During CNC machine tool machining, unstable chatter between the workpiece and the cutting tool can cause workpiece surface deterioration, affect cutting efficiency, and shorten the service life of machine tool components. With the increasing demand for high-precision machining technology in modern society, reducing chatter during machining has become a key research focus both domestically and internationally.

[0003] Currently, there are two main methods for suppressing chatter: passive and active. Passive methods mainly achieve this by increasing tool stiffness, designing special tool structures, or installing tuned mass dampers on the tool. Passive methods are simple and easy to implement, but they have drawbacks such as the inability to adjust in real time and a narrow suppression range. Active methods, on the other hand, suppress system vibration by introducing external actuators (such as electromagnetic, piezoelectric, electrorheological, and magnetorheological fluids) after identifying the system's unstable state. They have the advantages of high precision and a wide suppression range, but they also have the disadvantages of system complexity, high cost, and difficulty in widespread implementation. Summary of the Invention

[0004] This invention provides a vibration damping tool device and its design method based on a local resonant cantilever beam oscillator, which suppresses chattering that is easily generated during the machining of tools with large length-to-diameter ratios (turning tools, milling cutters, boring tools, etc.), thereby improving the machining accuracy of parts. The structure is installed outside the tool, without the need to modify the original system, and is easy to disassemble and assemble. By adjusting the relevant dimensional parameters of the local resonant oscillator, the vibration damping frequency band of the damping tool can be adjusted in real time.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a vibration reduction tool structure based on a local resonance cantilever beam oscillator, comprising a tool bar and a fixing ring and a circular ring oscillator sleeved on the tool bar. The fixing ring is used to fix the circular ring oscillator on the tool bar. The fixing ring and the tool bar are detachably connected. The fixing ring and the circular ring oscillator are connected by bolts and nuts. The circular ring oscillator is used to absorb the vibration of the tool bar.

[0006] The distance between the fixed ring and the circular oscillator is adjusted using bolts and nuts.

[0007] Furthermore, the fixed ring and the circular oscillator are connected to form a structural unit, and multiple such structural units are evenly arranged along the axial direction on the tool holder.

[0008] Furthermore, the structural units are oriented in the same direction.

[0009] Furthermore, the retaining ring is made of aluminum or nylon, the circular oscillator is made of steel or copper, and the bolts are made of nylon or resin.

[0010] Furthermore, the retaining ring is fastened to the tool holder by screws.

[0011] This invention also provides a design method for the above-mentioned vibration damping tool structure based on a locally resonant cantilever beam oscillator, comprising the following steps:

[0012] Obtain the tip frequency response function of the vibration damping tool structure, determine the first natural frequency of the vibration damping tool structure, and design the cantilever beam oscillator structure with the first natural frequency as the design target;

[0013] Based on the first natural frequency, the relationship between the stiffness k and mass m of the cantilever beam oscillator is determined. Combining the material and spatial size constraints of the bolt and the ring oscillator, a finite element model of the cantilever beam oscillator structure is established based on finite element software. The size, material and structural parameters of the finite element model are designed so that its first bending mode under fixed boundary conditions is consistent with the first natural frequency of the machine tool cutter structure.

[0014] A theoretical model of a vibration-damping tool structure based on a local resonant cantilever beam oscillator is established based on the spectral element method, and the vibration suppression range of the vibration-damping tool device based on the local resonant cantilever beam oscillator is obtained.

[0015] Furthermore, the theoretical model for a vibration-damping tool structure based on a locally resonant cantilever beam oscillator, established using the spectral element method, includes:

[0016] The cantilever beam oscillator structure is simplified to an equivalent spring-mass system. The spectral element matrices of the tool holder element and the cantilever beam oscillator element are established respectively. The spectral element matrix of the tool holder element is:

[0017]

[0018] in, , , , , , , , , E is the Young's modulus of the tool holder material, ρ is the material density, A is the cross-sectional area of ​​the tool holder, I is the moment of inertia of the tool holder, L is the length of the tool holder, ω is the angular frequency, and the spectral element matrix of the cantilever beam oscillator is:

[0019]

[0020] in, The angular frequency is used; a theoretical model of the vibration damping tool structure is obtained through finite element matrix assembly.

[0021] Furthermore, according to the formula The relationship between the required stiffness k and mass m of the cantilever beam oscillator can be obtained.

[0022] Furthermore, the tool tip frequency response function is obtained based on the force hammer modal test, and the first-order natural frequency of the tool is obtained based on the tool tip frequency response function.

[0023] Compared with existing technologies, this invention has at least the following advantages: Based on the theory of local resonance, this invention designs a tool structure with a wide frequency suppression range to suppress broadband chatter during cutting. A theoretical model is established using the spectral unit method, providing guidance for the structure design. The design of a detachable cantilever beam oscillator structure allows for convenient installation on the outer end of the tool, avoiding redesign of the tool structure and offering wide applicability. By adjusting the cantilever length, i.e., the distance between the fixed ring and the circular ring oscillator, the characteristic frequency of the oscillator can be adjusted in real time, thereby changing the tool's suppression range and enabling the tool to achieve the best vibration suppression effect in different usage scenarios. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of a vibration-damping tool structure based on a local resonance cantilever beam oscillator according to the present invention;

[0025] Figure 2 This is a model diagram of a cantilever beam oscillator.

[0026] Figure 3 This is a three-dimensional structural diagram of a fixed ring;

[0027] Figure 4 Schematic diagram of a circular ring oscillator;

[0028] Among them, 1 is the tool holder, 2 is the cantilever beam vibrator, 3 is the tool bar, 4 is the tool end, 5 is the bolt, 6 is the fastening screw, 7 is the retaining ring, 8 is the nut, and 9 is the ring vibrator. Detailed Implementation

[0029] The invention will be further described below with reference to the accompanying drawings.

[0030] This invention provides a vibration damping tool device based on a locally resonant cantilever beam oscillator, such as... Figure 1As shown, the specific implementation follows these steps: The tool is mounted on the machine tool spindle, and the tool tip frequency response function is tested using a modal hammer test to obtain the tool's first-order natural frequency. Based on the obtained first-order natural frequency, considering factors such as tool size, oscillator size, and bolt material, a cantilever beam oscillator structure is designed. The cantilever beam oscillator structure is modeled using finite element software, ensuring that the oscillator's first-order bending vibration natural frequency is the same as the tool's characteristic frequency. Subsequently, a model of the tool with the locally resonant cantilever beam oscillator is established using the spectral element method. The vibration suppression range of the locally resonant cantilever beam oscillator structure is calculated, and the dimensional parameters are adjusted to achieve the design target for the vibration suppression range.

[0031] Modal testing is performed on the tool structure actually installed on the machine tool to determine the frequency response function of the tool tip. The equipment required for the test includes a hammer, sensors (accelerometers or displacement sensors), and a data analysis system. The first-order natural frequency of the tool in its installed state is obtained. f This provides guidance for the design of cantilever beam oscillators.

[0032] Based on the first-order natural frequency obtained from tool modal testing, according to the formula... The relationship between the required cantilever beam oscillator stiffness k and mass m can be obtained. For pi, taking all factors into consideration Figure 2 In the oscillator structure shown, the materials (steel, aluminum, nylon, etc.) and spatial dimensions of bolt 5 and circular ring oscillator 9 are established using the finite element method. Appropriate dimensions (D2, D3, H) and materials are selected, where D2 is the inner diameter of the circular ring oscillator, D3 is the outer diameter of the circular ring oscillator, and H is the thickness of the circular ring oscillator, so that the first-order bending natural frequency of the oscillator is consistent with the first-order natural frequency of the tool.

[0033] When using the finite element method to calculate the natural frequency of an oscillator, Figure 3 The fixing ring shown is used for fixing. Figure 4 The circular oscillator shown vibrates freely, and the two parts are connected by bolt 8.

[0034] After obtaining a suitable cantilever beam oscillator structure, the cantilever beam oscillator structure is simplified to an equivalent spring-mass system. This cantilever beam oscillator structure is uniformly distributed on the tool holder at a spacing of 'a'. The spectral element matrix of each element is established using the spectral element method. The spectral element matrix of the tool holder, which is equivalent to a beam, is as follows:

[0035]

[0036]

[0037] Where E is the Young's modulus of the tool holder material, ρ is the material density, A is the cross-sectional area of ​​the tool holder, and I is the moment of inertia of the tool holder. L The length of the tool holder. For the angular frequency, similarly, the spectral element matrix of the cantilever beam oscillator is:

[0038]

[0039] In a local resonance vibration damping tool system, the oscillators are identical, and therefore the corresponding oscillator element matrices are identical. By assembling the spectral element matrices of these oscillators with the spectral element matrix of the beam, a theoretical analysis model of the entire vibration damping tool system can be obtained. This theoretical analysis model can be used to quickly calculate the vibration transmissibility curve of the vibration damping tool system, thereby obtaining the vibration suppression frequency range of the structure.

[0040] Figure 2 This is a schematic diagram of a cantilever beam oscillator structure. The cantilever beam structure shown includes... Figure 3 The fixed ring shown and Figure 4 The circular ring oscillator shown has a fixed ring that serves to fix the cantilever beam oscillator to the tool holder. The fixed ring and the tool holder are secured together by fastening screws 6. The fixed ring and the circular ring oscillator are connected by bolts 5 and nuts 8. The vibration of the circular ring oscillator driven by the bolts absorbs the vibration of the tool holder, achieving a vibration suppression effect. Adjusting the distance between the fixed ring and the circular ring oscillator allows for easy adjustment of the oscillator's characteristic frequency, thereby adjusting the vibration suppression range of the entire system. The specific range of this vibration suppression range can be quickly calculated using a theoretical model established by the spectral element method.

[0041] Figure 3 The retaining ring shown serves a fixing function. To reduce the impact of its added mass on the vibration characteristics of the overall tool system, its material can be a common lightweight metal or engineering plastic, such as aluminum or nylon. Figure 4 The circular ring oscillator shown is a mass element and can be made of materials with a large mass, such as steel or copper. Its mass can be adjusted by changing the inner diameter D2, outer diameter D3, and length H. The bolt 5 serves two purposes: first, to adjust the distance between the fixing ring and the circular ring oscillator; and second, to act as a stiffness element to drive the circular ring oscillator to vibrate. Its material can be made of materials with a small Young's modulus, such as resin, nylon, or PLA.

[0042] This invention, based on the local resonance mechanism, can generate a vibration suppression range within a set frequency band. The finite element matrix assembly method is modular and standardized; the tool holder matrix and the oscillator matrix are equivalent to two modules. The theoretical model is simplified according to the actual number of oscillators installed, following a standard matrix assembly process, which is convenient and fast. The cantilever beam oscillators are uniformly installed on the tool holder, forming a local resonance structure, thus reducing broadband chatter generated by the machine tool during machining. This invention has a simple structure, is easy to manufacture and implement, and the vibration suppression range can be adjusted in real time by changing the characteristic frequency of the oscillators according to the actual machining conditions, resulting in a significant vibration suppression effect without requiring changes to the original tool structure.

[0043] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A design method of a vibration-damping tool structure based on a local resonance cantilever beam vibrator, characterized by, The vibration reduction tool structure based on the local resonance cantilever beam oscillator includes a tool holder (3), a fixing ring (7) and a circular ring oscillator (9) sleeved on the tool holder. The fixing ring (7) is used to fix the circular ring oscillator (9) on the tool holder. The fixing ring (7) and the tool holder (3) are detachably connected. The fixing ring (7) and the circular ring oscillator (9) are connected by bolts (5) and nuts (8). The circular ring oscillator (9) is used to absorb the vibration of the tool holder. The design method includes the following steps: Obtain the tip frequency response function of the vibration damping tool structure, determine the first natural frequency of the vibration damping tool structure, and design the cantilever beam oscillator structure with the first natural frequency as the design target; Based on the first natural frequency, the relationship between the stiffness k and mass m of the cantilever beam oscillator is determined. Combining the material and spatial size constraints of the bolt (5) and the ring oscillator (9), a finite element model of the cantilever beam oscillator structure is established based on the finite element software. The size, material and structural parameters of the finite element model are designed so that its first bending mode under fixed boundary conditions is consistent with the first natural frequency. A theoretical model of a vibration-damping tool structure based on a local resonant cantilever beam oscillator is established based on the spectral element method, and the vibration suppression range of the vibration-damping tool device based on the local resonant cantilever beam oscillator is obtained. The theoretical model of a vibration-damping tool structure based on a local resonant cantilever beam oscillator, established using the spectral element method, includes: The cantilever beam oscillator structure is simplified to an equivalent spring-mass system. The spectral element matrices of the tool holder element and the cantilever beam oscillator element are established respectively. The spectral element matrix of the tool holder element is: wherein, , , , , , , , , , E is the Young's modulus of the tool bar material, p is the material density, A is the cross-sectional area of the tool bar, I is the moment of inertia of the tool bar, L is the length of the tool bar, and w is the circular frequency. The spectral element matrix of the cantilever beam vibrator is: wherein is the circular frequency; the theoretical model of the vibration-damping tool structure is obtained by the finite element matrix assembly method.

2. The design method of a vibration-damping tool structure based on a local resonance cantilever beam resonator according to claim 1, wherein The distance between the fixed ring (7) and the circular oscillator (9) is adjusted by bolts (5) and nuts (8).

3. The design method of a vibration-damping tool structure based on a local resonance cantilever beam resonator according to Claim 1, wherein The fixed ring (7) and the circular ring oscillator (9) are connected to form a structural unit (2), and multiple structural units (2) are evenly arranged along the axial direction on the tool bar (3).

4. The design method of a vibration-damping tool structure based on a local resonance cantilever beam resonator according to Claim 3, wherein The structural units (2) are all oriented in the same direction.

5. The design method of a vibration-damping tool structure based on a local resonance cantilever beam resonator according to Claim 1, wherein The fixing ring (7) is made of aluminum or nylon, the ring vibrator (9) is made of steel or copper, and the bolt (5) is made of nylon or resin.

6. The design method of a vibration-damping tool structure based on a local resonance cantilever beam resonator according to Claim 1, wherein The retaining ring (7) is fastened to the tool bar by screws (6).

7. The design method of a vibration-damping tool structure based on a local resonance cantilever beam resonator according to Claim 1, wherein According to the formula The relationship between the required cantilever beam resonator stiffness k and mass m is obtained, f is the first order natural frequency of the tool in the mounted state.

8. The design method of a vibration-damping tool structure based on a local resonance cantilever beam resonator according to Claim 1, wherein The tool tip frequency response function is obtained based on the force hammer modal test, and the tool's first-order natural frequency is obtained based on the tool tip frequency response function.

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