A built-in adjustable stiffness magneto-rheological elastomer vibration absorption type damping boring bar

Abstract

The present application relates to magnetic mechanical processing equipment technical field, especially to a built-in adjustable stiffness magnetorheological elastomer vibration absorption type damping boring bar, comprising: a tool bar body for supporting the position of a tool head after assembly, a sealed cavity is formed in the axial interior of one end of the tool bar body; a tool head packaging assembly installed at the end of the tool bar body; a damping assembly installed inside the sealed cavity of the tool bar body. The built-in adjustable stiffness magnetorheological elastomer vibration absorption type damping boring bar provided by the present application integrates the variable stiffness damping assembly in the internal cavity of the boring bar body, maintains the integrity and regularity of the boring bar outer diameter, has reasonable space layout, realizes interference-free deep hole machining, ensures that the damping device does not interfere with the inner wall of the workpiece during operation, thereby effectively suppressing the chatter of the large length-diameter ratio boring bar without limiting the machining depth, and significantly improving the size accuracy and surface roughness of deep hole machining.

Description

Technical Field

[0001] This invention relates to the field of magnetic machining equipment technology, and in particular to a vibration-damping boring bar with a built-in adjustable stiffness magnetorheological elastomer for vibration absorption. Background Technology

[0002] As a key component in deep hole machining, the boring bar, with its large length-to-diameter ratio and low stiffness, is highly susceptible to chatter during cutting, leading to deterioration of the machined surface quality, shortened tool life, and limited machining efficiency. Therefore, suppressing boring bar vibration is a core technical challenge for improving the accuracy and stability of deep hole machining. Existing boring bar vibration reduction technologies are mainly divided into passive, active, and semi-active vibration reduction. Passive vibration-damping boring bars, such as impact dampers and tuned mass dampers, are simple in structure and low in cost, but their damping and stiffness parameters are fixed. Once machining conditions, such as spindle speed and cutting depth, change, their vibration reduction effect will significantly decrease, making them unsuitable for wide-range, variable-condition machining. Active vibration-damping boring bars, such as those based on piezoelectric ceramics and electromagnetic actuators, achieve strong vibration suppression through external energy input and closed-loop control, exhibiting superior performance. However, their systems are complex, costly, and require external power supplies and complex control algorithms, posing challenges in terms of reliability and maintainability in industrial settings. Semi-active vibration damping technology combines the reliability of passive systems with the adjustability of active systems, making it a current research hotspot. Among these, smart fluid-based solutions, such as semi-active boring bars using magnetorheological (MR) fluids, have been proposed. These adjust the fluid viscosity by changing the magnetic field, thereby altering the damping characteristics. However, magnetorheological fluids present challenges, including the need for sealing, potential particle settling, and the need for complex fluid loop designs. Another approach is to use variable stiffness vibration absorbers. Magnetorheological elastomers (MREs), as an emerging smart material, exhibit a rapid, reversible, and continuous change in their elastic modulus with an applied magnetic field. This characteristic makes them ideal components for dynamically adjustable vibration absorbers, particularly in terms of stiffness. MRE-based absorbers, by adjusting the magnetic field to change their stiffness, can actively track changes in the external excitation frequency, thus achieving effective vibration damping over a wide frequency band.

[0003] Therefore, there is an urgent need for a new type of semi-active vibration damping boring bar that is compact, quick to adjust, reliable in operation, and adaptable to the wide range of working conditions in boring operations, in order to overcome the shortcomings of existing technologies. Summary of the Invention

[0004] Therefore, it is necessary to address the aforementioned technical problems by providing a vibration-damping boring bar with a built-in adjustable stiffness magnetorheological elastomer for vibration absorption. This addresses the issue that existing boring bar vibration dampers, which are mostly external or passive structures, are prone to direct contact and physical interference with the workpiece's inner wall during deep hole machining, or the boring bar itself may experience chatter due to insufficient stiffness. This not only limits the machining depth but may also damage the machined surface due to collisions, leading to a significant decrease in machining accuracy or even the inability to complete the machining task. Traditional passive vibration dampers typically only dampen vibrations at specific frequencies, making it difficult to adapt to the complex machining conditions where cutting forces are constantly changing.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A vibration-damping boring bar with built-in adjustable stiffness magnetorheological elastomer vibration absorption includes: The tool holder body is used to support the position of the tool head after assembly, and a sealed cavity is opened in the axial interior of one end of the tool holder body; The cutting head encapsulation assembly is installed at the end of the cutting head body and is used to encapsulate and close the assembly position at the end of the cutting head body. The vibration damping component is installed inside the sealed cavity of the tool holder body; The vibration damping component includes: A connecting beam is threaded into the inside of the sealed cavity, and a positioner is sleeved on the outside of the connecting beam; The mass block is positioned on the outside of the connecting beam and does not contact the position of the locator. A magnetorheological elastomer is used to cover the outside of the positioner mounted on the connecting beam.

[0006] As a preferred embodiment of the built-in adjustable stiffness magnetorheological elastomer vibration damping boring bar provided by the present invention, a cutting head is provided at one end of the tool bar body, and a blade is provided at the bottom of the cutting head at the end away from the tool bar body.

[0007] As a preferred embodiment of the vibration-damping boring bar with built-in adjustable stiffness magnetorheological elastomer vibration absorption provided by the present invention, the tool head packaging assembly includes: A washer is provided at one end of the tool holder body, and a top cap is provided at the end of the washer near the tool holder body. The sealing platform is located at the top end of the tool holder body, sealing one end. The encapsulation cover is located at the end of the encapsulation platform away from the top cover. The connecting beam is threadedly connected to the encapsulation cover to achieve the closure of the sealing cavity inside the tool bar body.

[0008] As a preferred embodiment of the built-in adjustable stiffness magnetorheological elastomer vibration damping boring bar provided by the present invention, the washer, the top cover and the encapsulation platform are all right-angled triangles with threaded holes at the vertices of the triangles. The cutting head, washer, top cover and encapsulation platform are axially connected in sequence by bolts and threaded holes.

[0009] In a preferred embodiment of the built-in adjustable stiffness magnetorheological elastomer vibration damping boring bar provided by the present invention, the encapsulation platform and the encapsulation cover are fixedly connected in a triangular shape by three threaded nails.

[0010] As a preferred embodiment of the vibration-damping boring bar with built-in adjustable stiffness magnetorheological elastomer provided by the present invention, the inside of the washer, the top cover, the encapsulation platform and the encapsulation cover are all provided with openings for conducting wires along the axial or radial path.

[0011] As a preferred embodiment of the vibration-damping boring bar with built-in adjustable stiffness magnetorheological elastomer provided by the present invention, it further includes an excitation component installed on the radial outer periphery of the magnetorheological elastomer for adjusting the magnetorheological elastomer.

[0012] As a preferred embodiment of the vibration-damping boring bar with built-in adjustable stiffness magnetorheological elastomer vibration absorption provided by the present invention, the excitation component includes: The coil frame is mounted on the radially outer side of the magnetorheological elastomer; The excitation coil is wound around the outside of the coil frame.

[0013] As a preferred embodiment of the vibration damping boring bar with built-in adjustable stiffness magnetorheological elastomer provided by the present invention, a sleeve protective layer is provided inside the sealed cavity and outside the excitation coil.

[0014] It is clear without a doubt that the technical solution described above in this application can solve the technical problem that this application aims to address.

[0015] Meanwhile, through the above technical solutions, the present invention has at least the following beneficial effects: 1. The present invention provides a built-in adjustable stiffness magnetorheological elastomer vibration damping boring bar. By integrating the variable stiffness vibration damping component into the internal cavity of the boring bar body, the integrity and regularity of the boring bar's outer diameter are maintained, the spatial layout is reasonable, and interference-free deep hole machining is achieved. It ensures that the vibration damping device will not physically interfere with the inner wall of the workpiece during operation, thereby effectively suppressing the chatter of boring bars with large length-to-diameter ratios without limiting the machining depth, and significantly improving the dimensional accuracy and surface roughness of deep hole machining.

[0016] 2. This invention employs a magnetorheological elastomer (MRE) in conjunction with a mass block to construct a variable stiffness vibration reduction system. By adjusting the current in the excitation coil, the shear stiffness of the MRE can be precisely and continuously controlled. Due to the millisecond-level response speed and good reversibility of the MRE, this device can adjust the resonant frequency of the vibration absorber system in real time to match the external excitation frequency, thereby achieving active and rapid suppression of flutter over a wide frequency range. Its agile response characteristics enable broadband vibration reduction.

[0017] 3. This invention, through the combined design of a symmetrical connecting beam and a positioner, ensures the dynamic stability of the mass block in terms of vibration absorption, resulting in strong structural stability and improved overall equipment efficiency. This high-precision vibration reduction solution not only effectively extends the service life of cutting tools and reduces machining noise, but also significantly improves production efficiency. It has extremely high industrial application value and promising prospects for technology promotion in the fields of difficult-to-machine materials and ultra-deep hole boring. Attached Figure Description

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

[0019] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the coil frame of the present invention without coils; Figure 3 This is a wiring diagram of the power-conducting wires of the boring bar tool head packaging component of the present invention; Figure 4 This is a schematic diagram of the connecting beam of the present invention; Figure 5 This is a schematic diagram of the structure of the sleeve protective layer of the present invention; Figure 6 This is a schematic diagram of the structure of the mass block of the present invention; Figure 7 This is a schematic diagram of the structure of the magnetorheological elastomer of the present invention; Figure 8 This is a schematic diagram of the positioner of the present invention.

[0020] In the diagram: 1. Blade; 2. Blade head; 3. Bolt; 4. Washer; 5. Top cap; 6. Encapsulation platform; 7. Encapsulation cover; 8. Coil frame; 9. Sleeve protective layer; 10. Positioner; 11. Connecting beam; 12. Mass block; 13. Magnetorheological elastomer; 14. Blade holder body; 15. Current source. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0022] To enable those skilled in the art to better understand the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0023] It should be noted that, unless otherwise specified, the embodiments and features and technical solutions in the present invention can be combined with each other.

[0024] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0025] Reference Figures 1-8 A vibration damping boring bar with built-in adjustable stiffness magnetorheological elastomer for vibration absorption, comprising: The tool holder 14 is used to support the position of the tool head 2 after assembly. A sealed cavity is opened in the axial interior of one end of the tool holder 14, and the sealed cavity is cylindrical. The tool head 2 is provided at one end of the tool holder 14, and the blade 1 is provided at the bottom of the end of the tool head 2 away from the tool holder 14, so that when the vibration damping boring bar is working, it can achieve contact work through the blade 1. The cutting head encapsulation assembly is installed at the end of the cutting head shank 14 and is used to encapsulate and close the assembly position at the end of the cutting head shank 14. The blade packaging assembly includes: Washer 4 is provided at one end of the tool holder body 14, and a top cap 5 is provided at the end of washer 4 near the tool holder body 14. The encapsulation stage 6 is located at one end of the top cover 5 inside the tool bar body 14, so as to position the encapsulation stage 6 by the position of the top cover 5. Preferably, the washer 4, the top cap 5, and the encapsulation platform 6 each have a threaded hole centered at the vertex of a right-angled triangle. The cutter head 2, washer 4, top cap 5, and encapsulation platform 6 are axially connected in sequence by bolts 3 and the threaded holes. This ensures that the internal threaded holes of the washer 4, top cap 5, and encapsulation platform 6 are aligned during assembly. The connection of the high-strength bolts 3 forms the encapsulation part, which encapsulates the end of the cutter body 14. This not only constitutes a stable cutter head encapsulation part but also achieves synchronous sealing of the internal cavity and enables connection to the cutter head 2.

[0026] The encapsulation cover 7 is located at the end of the encapsulation platform 6 away from the top cover 5, and is used to close the sealing cavity inside the tool bar body 14. Preferably, the encapsulation platform 6 and the encapsulation cover 7 are fixedly connected in a triangle by three threaded nails. Each of the encapsulation platform 6 and the encapsulation cover 7 has three threaded holes at the vertices of the right triangle. The threaded holes of the encapsulation cover 7 are through, while the threaded holes of the encapsulation platform 6 are not through. The connection between the two is achieved by screws.

[0027] A vibration damping component is installed inside the sealed cavity of the tool holder body 14; thus, a threaded connection end is started inside the sealed cavity at the end away from the tool head encapsulation component for installing the vibration damping component; The vibration damping components include: The connecting beam 11 is threadedly connected to the inside of the sealed cavity, and the connecting beam 11 is also threadedly connected to the encapsulation cover 7. This allows the connecting beam 11 to be installed at the threaded end of the sealed cavity through the threaded connection at one end, and the encapsulation cover 7 to be installed on the outside of the other end of the connecting beam 11 through the threaded connection. This completes the assembly and encapsulation of the encapsulation cover 7 inside the sealed cavity of the tool holder 14. A positioner 10 is sleeved on the outside of the connecting beam 11, allowing the positioner 10 to be slidably assembled on the outside of both ends of the connecting beam 11. The positioner 10 is prevented from sliding left or right after being assembled on the outside of the connecting beam 11 by the limiting blocks on the connecting beam 11. In other embodiments, the inner wall of the cavity is provided with a support platform for mounting the connecting beam 11. The connecting beam 11 is fixed on the support platform by fasteners to ensure that the dynamic mechanical properties are transmitted to the vibration reduction system under cutting load and to guarantee its stable dynamic mechanical properties.

[0028] The mass block 12 is set on the outside of the connecting beam 11, and the mass block 12 is suspended in the position inside the sealed cavity by the connecting beam 11 which is symmetrically arranged on the left and right sides. At the same time, the mass block 12 is assembled with the threaded connection at the end of the connecting beam 11 through the internal threaded hole. The magnetorheological elastomer 13 is wrapped around the outside of the positioner 10 assembled on the connecting beam 11, so that the magnetorheological elastomer 13 is assembled in the vibration deformation area of ​​the connecting beam 11, and at the same time, the magnetorheological elastomer 13 is wrapped in the shape of a hollow cylindrical structure. An excitation assembly is installed on the radial outer periphery of the magnetorheological elastomer 13 to achieve adjustment of the magnetorheological elastomer 13; Preferably, the magnetorheological elastomer 13 has an annular cylindrical structure, with its inner ring being locked and limited by the locator 10 and the connecting beam 11, and its outer ring being adapted to the inner diameter of the coil frame 8 of the excitation system.

[0029] The excitation assembly includes: The coil frame 8 is installed on the radial outer side of the magnetorheological elastomer 13, so that the outer side of the coil frame 8 is provided with a positioning groove, and its inner diameter is adapted to the outer ring structure of the magnetorheological elastomer 13 to form a compact radial coupling structure. The excitation coil is wound around the outside of the coil frame 8, and the number of excitation coils can be multiple. At the same time, the excitation coil is wound continuously in series with a single copper wire. In this embodiment, the excitation coil includes a left excitation coil and a right excitation coil. The left and right excitation coils are continuously wound from the same copper wire and are connected in series. The lead end of the copper wire passes through the bar body 14 and is electrically connected to the external DC current source 15.

[0030] Preferably, a sleeve protective layer 9 is provided inside the sealed cavity and outside the excitation coil, and the sleeve protective layer 9 is semi-circular in shape, so that the excitation assembly after assembly is protected on the outside of the magnetorheological elastomer 13 through the symmetrical arrangement of the sleeve protective layer 9. Preferably, the gasket 4, the top cover 5, the encapsulation platform 6 and the encapsulation cover 7 are all provided with small openings for conductive wires along the axial or radial path inside, so as to realize the wiring of the excitation component and allow the end of the wire to pass smoothly through the encapsulation part and reliably connect with the external DC current source 15 while ensuring the sealing performance.

[0031] In this embodiment, each structure has its own service life. In actual manufacturing and application, the corresponding structure made of different materials can be replaced according to the needs of use.

[0032] In this embodiment, under the action of a magnetic field, the effective shear modulus of the hollow cylindrical magnetorheological elastomer 13 changes, resulting in a change in the stiffness of the magnetorheological elastomer 13. This change in stiffness alters the absorption bandwidth and effect of the vibration absorber. Therefore, by changing the strength of the magnetic field passing through the magnetorheological elastomer 13, the effective absorption frequency band of the vibration absorber can be adjusted to be equal to the external excitation frequency, thereby fully utilizing the vibration reduction performance of the vibration absorber and achieving the purpose of broadband vibration reduction.

[0033] In this embodiment, the stiffness of the magnetorheological elastomer 13 is controlled by adjusting the current intensity of the excitation coil. The magnetorheological elastomer 13 operates in shear mode. The natural frequency of the damper... It can be obtained from the following model: Stiffness of magnetorheological elastomer 13 ,in For effective shear modulus, For effective shear area, For thickness.

[0034] Effective shear modulus ,in The modulus under zero magnetic field, This represents the change in quantity under the influence of a magnetic field.

[0035] The natural frequency of the vibration damper ,in The mass of the mass block.

[0036] In this embodiment, under the action of a magnetic field, the effective shear modulus of the cylindrical magnetorheological elastomer 13 changes, leading to a change in the stiffness of the hollow cylindrical magnetorheological elastomer 13. This change in stiffness alters the shear modulus of the vibration damper. Therefore, by changing the strength of the magnetic field passing through the magnetorheological elastomer 13, the vibration absorption bandwidth of the vibration absorber system can be adjusted to be equal to the external excitation frequency, fully utilizing the vibration damping performance of the vibration absorber and achieving the purpose of wide-frequency vibration damping. This invention integrates the vibration damping component inside the boring bar, maintaining the regularity of the boring bar's outer diameter. While ensuring interference-free deep hole machining, it significantly improves machining stability and workpiece accuracy.

[0037] The actual processing application steps in this embodiment are as follows: Step 1: Install the vibration damping boring bar on a machine tool and install an acceleration sensor at the front end of the bar. Step 2: Determine the cutting parameters according to the workpiece requirements and perform a trial cut, collecting vibration signals in real time through sensors; Step 3: Adjust the current flowing through the excitation coil according to the acquired frequency signal to adjust the resonant frequency of the vibration absorber section. The system can match the external excitation frequency in real time and utilize the 13-millisecond response characteristics of the magnetorheological elastomer to achieve wideband active vibration isolation until the processing is completed.

[0038] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A vibration-damping boring bar with built-in adjustable stiffness magnetorheological elastomer for vibration absorption, characterized in that, include: The tool holder body (14) is used to support the position of the tool head (2) after assembly. A sealed cavity is provided in the axial interior of one end of the tool holder body (14). The cutting head encapsulation assembly is installed at the end of the cutting bar body (14) and is used to encapsulate and close the assembly position at the end of the cutting bar body (14); The vibration damping assembly is installed inside the sealed cavity of the tool bar body (14); The vibration damping component includes: A connecting beam (11) is threadedly connected to the inside of the sealed cavity, and a locator (10) is sleeved on the outside of the connecting beam (11). The mass block (12) is located on the outside of the connecting beam (11) and does not contact the position of the locator (10); A magnetorheological elastomer (13) is wrapped around the outside of the positioner (10) mounted on the connecting beam (11).

2. The vibration-damping boring bar with built-in adjustable stiffness magnetorheological elastomer vibration absorption as described in claim 1, characterized in that, One end of the cutter bar (14) is provided with a cutter head (2), and the bottom of the cutter head (2) away from the cutter bar (14) is provided with a blade (1).

3. A vibration-damping boring bar with built-in adjustable stiffness magnetorheological elastomer vibration absorption as described in claim 1, characterized in that, The blade encapsulation assembly includes: A washer (4) is provided at one end of the tool bar body (14), and a top cap (5) is provided at the end of the washer (4) near the tool bar body (14). The sealing platform (6) is set at one end of the top cap (5) inside the blade bar body (14); The encapsulation cover (7) is located at the end of the encapsulation platform (6) away from the top cover (5). The connecting beam (11) is threadedly connected to the encapsulation cover (7) to achieve the closure of the sealing cavity inside the tool bar body (14).

4. A vibration-damping boring bar with built-in adjustable stiffness magnetorheological elastomer vibration absorption as described in claim 3, characterized in that, The washer (4), the top cap (5), and the encapsulation platform (6) are all right-angled triangles with threaded holes at the apex of each triangle. The cutter head (2), washer (4), top cap (5), and encapsulation platform (6) are axially connected by bolts (3) and threaded holes.

5. A vibration-damping boring bar with built-in adjustable stiffness magnetorheological elastomer vibration absorption as described in claim 3, characterized in that, The encapsulation platform (6) and the encapsulation cover (7) are fixedly connected in a triangular shape by three threaded nails.

6. A vibration-damping boring bar with built-in adjustable stiffness magnetorheological elastomer vibration absorption as described in claim 3, characterized in that, The gasket (4), top cap (5), encapsulation platform (6) and encapsulation cover (7) all have openings for conducting wires along the axial or radial path inside.

7. A vibration-damping boring bar with built-in adjustable stiffness magnetorheological elastomer vibration absorption as described in claim 1, characterized in that, It also includes an excitation assembly, which is installed on the radial outer periphery of the magnetorheological elastomer (13) for adjusting the magnetorheological elastomer (13).

8. A vibration-damping boring bar with built-in adjustable stiffness magnetorheological elastomer vibration absorption as described in claim 7, characterized in that, The excitation assembly includes: The coil frame (8) is installed on the radial outer side of the magnetorheological elastomer (13); The excitation coil is wound around the outside of the coil frame (8).

9. A vibration-damping boring bar with built-in adjustable stiffness magnetorheological elastomer vibration absorption as described in claim 8, characterized in that, A sleeve protective layer (9) is provided inside the sealed cavity and outside the excitation coil.

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