Curved beam variable rigidity fast tool servo device and using method thereof

Abstract

The invention belongs to the technical field of precision machining equipment, and discloses a curved beam variable-rigidity fast tool servo device and a using method thereof.The curved beam variable-rigidity fast tool servo device comprises three flexible mechanisms, namely a single straight circular flexible hinge playing a guiding role, a straight beam flexible hinge and a flexible curved beam playing a variable-rigidity function; the driving component comprises three groups of piezoelectric ceramics and is used for driving the flexible mechanism to deform; the magnetorheological elastomer is mainly used for changing the rigidity of the structure; the tool rest seat and the rigid base are mainly used for placing tools; according to the invention, rigidity change of the magnetorheological elastomer and pretightening force provided for the curved beam by the piezoelectric ceramics on the left side and the right side can be realized simultaneously through an external magnetic field, so that the rigidity of the flexible curved beam is changed, and the rigidity of the flexible curved beam and the rigidity of the core layer magnetorheological elastomer are connected in parallel; therefore, the rigidity of the device can be changed independently and also can be changed synergistically.

Description

Technical Field

[0001] The invention belongs to the technical field of precision machining equipment and relates to a curved beam variable stiffness fast tool servo device and a use method thereof. Background Art

[0002] Fast tool servo mechanism, referred to as fast tool servo, is a commonly used auxiliary mechanism in ultra-precision machining. It is mostly used in turning processes. It controls fast tools to process complex surfaces at a higher frequency through a macro-micro scale composite method to obtain more precise optical surfaces. In the process of complex surface machining, different structures and control methods need to be selected to achieve different machining goals, so it is necessary to design different fast tool servo structures.

[0003] Flexible hinge units, also called flexible hinges, are usually used in fast tool servo mechanisms to guide input displacements and decouple multi-directional displacement inputs. They have both structural characteristics and material characteristics brought by the selected materials. However, once the material parameter characteristics are determined, their stiffness is already determined.

[0004] Stiffness parallel means that when multiple springs or elastic elements are connected together in parallel, their total stiffness is equal to the sum of the stiffness of each spring or elastic element. At this time, the deformation of each spring or elastic element is the same.

[0005] The Euler flexible curved beam structure is mostly used in shock absorption systems. According to existing data, the Euler flexible curved beam has different sensitivities to the output stiffness in the diameter direction as the preload force loaded in the axial direction varies. That is, the output force corresponding to different displacements at the output end is different, and the output stiffness of the structure changes.

[0006] In the prior art, the patent application number is 2018105880330, and the patent name is a patent for a cam tensioning stiffness adjustable fast knife servo system. It introduces a cam mechanism to adjust the stiffness of the flexible mechanism, which is a mechanical adjustment and is inevitably affected by impact vibration. The patent application number is 2020111854449, and the patent name is a patent for a stiffness self-adjusting fast knife servo device. Although it proposes a magnetorheological elastomer, it only relies on the change of the elastic modulus of the magnetorheological elastomer to adjust the stiffness of the structure, and the adjustable range is very limited. The application number is 2024109945378, and the patent name is a magnetorheological stiffness fast knife servo device. Although it realizes the continuous dynamic change of the overall stiffness of the fast knife servo, the magnetorheological fluid has the disadvantages of low performance, easy leakage and difficult sealing during operation, poor sedimentation stability of solid phase particles in the composition, and the resulting unstable operation of the device, and unsatisfactory heat dissipation effect of the device.

[0007] Therefore, a curved beam variable stiffness fast tool servo device and a use method thereof are provided to solve the above-mentioned problems. Summary of the invention

[0008] In order to solve the technical problems that the stiffness of traditional fast tool servo mechanisms is usually a constant value and cannot be adjusted, and that the working performance of magnetorheological fluid is unstable when magnetorheological fluid is used to achieve the effect of variable stiffness of the structure, the present invention proposes a curved beam variable stiffness fast tool servo device and a method of using the same. In the structure, the flexible curved beam and the core layer magnetorheological elastomer are in a parallel relationship, that is, the two structures are in a parallel relationship in spatial distribution, that is, the total output stiffness of the device is the sum of the stiffness contributed by the curved beam structure to the output end and the stiffness contributed by the magnetorheological elastomer to the output end. The stiffness of the flexible curved beam and the core layer magnetorheological elastomer are independently controlled and adjusted independently or collaboratively to achieve dynamic adjustment of the stiffness of the structural output end, that is, the stiffness of the turning tool.

[0009] In order to solve the above technical problems, the present invention is implemented by adopting the following technical solutions, which are described as follows in conjunction with the accompanying drawings:

[0010] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0011] A curved beam variable stiffness fast tool servo device, comprising a single straight circular flexible hinge 1, a fine-tuning component 2, a driving component 3, and a variable stiffness mechanism 4;

[0012] The fine-tuning component 2 includes a straight beam flexible hinge 201 and a pre-tightening bolt 202;

[0013] The straight beam flexible hinge 201 is located at the rear side of the driving component 3;

[0014] The straight beam flexible hinge 201 is fine-tuned and driven by the pre-tightening bolt 202, thereby fine-tuning the pre-tightening driving component 3;

[0015] The variable stiffness mechanism 4 is composed of a rigid structure 401, a flexible curved beam 402, and a core layer magnetorheological elastomer 403;

[0016] The single straight circular flexible hinge 1 is directly connected to the rigid structure 401;

[0017] The flexible curved beam 402 and the core layer magnetorheological elastomer 403 are integrally and directly fixedly connected to the turning tool holder 5 .

[0018] Furthermore, the driving component 3 is composed of three groups of piezoelectric ceramics, which are divided into two categories; the first group of piezoelectric ceramics 301 and the second group of piezoelectric ceramics 302 together constitute the first type of piezoelectric ceramics, and the first type of piezoelectric ceramics are located on the rigid structure 401, and play a role in pre-tightening the flexible curved beam 402; the third group of piezoelectric ceramics 303 are the second type of piezoelectric ceramics, and the second type of piezoelectric ceramics are located on the tool holder 5, and play a role in driving the tool holder 5 and the tool installed on the tool holder to a predetermined position.

[0019] Furthermore, the single straight circular flexible hinge 1 is symmetrically distributed on both sides relative to the central axis direction of the tool holder 5, and plays a role in guiding the displacement input by the driving component 3 and uncoupling the front-to-back and left-to-right displacement input.

[0020] Furthermore, the variable stiffness mechanism 4 is symmetrically distributed on both sides relative to the central axis direction of the tool holder 5.

[0021] The flexible curved beam 402 in the single-sided variable stiffness mechanism 4 is provided with two pieces, sandwiching the magnetorheological elastomer 403 without a gap.

[0022] Furthermore, the magnetorheological elastomer is formed by closely stacking magnetorheological elastic sheets formed by solidifying polydimethylsiloxane (PDMS) mixed with carbonyl iron particles, and the shape of the magnetorheological elastomer is consistent with the shape of the flexible curved beam.

[0023] Furthermore, the fine-tuning components 2 are located on a rigid base frame 6 and are arranged in three groups.

[0024] Furthermore, three straight beam flexible hinges 201 are provided, all of which are located at the rear side of the driving component 3 and at the front end of the pre-tightening bolt 202 .

[0025] Furthermore, the rigid base frame 6 constitutes the structural basis of the variable stiffness fast tool servo device, and the construction of the single straight circular flexible hinge 1, the fine-tuning component 2, the driving component 3, and the variable stiffness mechanism 4 components are adapted to the design distribution position and size of the rigid base frame 6.

[0026] A method for using a curved beam variable stiffness fast tool servo device, characterized in that:

[0027] The first type of piezoelectric ceramics on both sides are extended correspondingly due to the application of external voltage, giving the flexible curved beam 402 a corresponding preload displacement;

[0028] After the flexible curved beam 402 is pre-tightened, the piezoelectric ceramic 3 of the second type of driving component located at the rear side of the tool holder generates a corresponding extension due to the application of the external voltage, so that the tool installed at the tool hole 501 on the tool holder 5 reaches the predetermined processing position;

[0029] By applying different external voltages to the piezoelectric ceramic 3 of the first type of driving component, the flexible curved beam 402 will be pre-tightened to different degrees; the piezoelectric ceramic 3 of the second type of driving component on the rear side of the tool holder will produce the same elongation when the same external voltage is applied; the forces at the output end of the tool are different; different output displacements at the output end of the structure correspond to different output forces, and the output stiffness changes;

[0030] The curved beam 402 and the magnetorheological elastomer 403 are in parallel relationship, and the output stiffness is regulated by the coordinated changes of the flexible curved beam 402 and the magnetorheological elastomer 403 .

[0031] Furthermore, a small pre-tightening force is applied to the straight beam flexible hinge 201 by fine-tuning the pre-tightening bolt 202, thereby fine-tuning the pre-tightening of the first type of piezoelectric ceramic.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The flexible curved beam structure used in the present invention has the advantages of small size, high precision and easy to achieve variable stiffness characteristics. Due to the buckling deformation, the flexible curved beam has high sensitivity to the preload displacement in the axial direction, that is, only micron-level displacement input is required to cause obvious deformation of the flexible curved beam, which will cause the flexible curved beam to have significantly different displacements in the direction perpendicular to its axis under the same force conditions, that is, the stiffness changes significantly.

[0034] The present invention utilizes a magnetorheological elastomer structure to ensure that the structure has a magnetorheological effect, thereby avoiding the disadvantages of low performance of the magnetorheological fluid itself; easy leakage and difficulty in sealing during operation; poor sedimentation stability of solid phase particles in the components and the resulting unstable operation of the device; and unsatisfactory heat dissipation effect of the device.

[0035] In the variable stiffness component of the present invention, the stiffness of the magnetorheological elastomer itself can be changed through the magnetic field; and the flexible curved beam can be displaced and pre-tightened by the driving component to cause the deformation of the flexible curved beam structure, thereby changing the output stiffness of the turning tool. The two can work together or change the output stiffness of the turning tool separately, and the output stiffness of the fast tool servo mechanism can be dynamically adjusted, so that the working bandwidth of the structure can be expanded. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The present invention will be further described below in conjunction with the accompanying drawings:

[0037] Figure 1 It is a front view of a curved beam variable stiffness fast tool servo device of the present invention;

[0038] Figure 2 It is a vertical and horizontal isometric view of a curved beam variable stiffness fast tool servo device of the present invention;

[0039] Figure 3It is a schematic structural diagram of a single straight circle flexible hinge component of a curved beam variable stiffness fast tool servo device of the present invention;

[0040] Figure 4 It is a structural schematic diagram of a fine-tuning component of a curved beam variable-rigidity fast-tool servo device of the present invention;

[0041] Figure 5 It is a schematic diagram of a variable stiffness structure of a curved beam variable stiffness fast tool servo device of the present invention;

[0042] Among them, 1-single straight circular flexible hinge, 2-fine-tuning component, 201-straight beam flexible hinge, 202-pre-tightening bolt hole, 301-first type piezoelectric ceramic, 302-first type piezoelectric ceramic, 303-second type piezoelectric ceramic, 4-variable stiffness component, 401-rigid structure, 402-flexible curved beam, 403-magnetorheological elastomer structure, 5-turning tool holder, 501-turning tool mounting hole, 6-rigid base frame. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical scheme and advantages of the implementation of the present invention clearer, the technical scheme in the embodiment of the present invention will be described in more detail below in conjunction with the drawings in the embodiment of the present invention. In the drawings, the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The described embodiments are part of the embodiments of the present invention, not all of the embodiments. The embodiments described below with reference to the drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limitations on the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. The embodiments of the present invention are described in detail below in conjunction with the drawings.

[0044] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the scope of protection of the present invention.

[0045] The present invention is described in detail below in conjunction with the accompanying drawings:

[0046] The present invention provides an embodiment, a curved beam variable stiffness fast tool servo device, comprising:

[0047] Reference Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 The present invention provides a curved beam variable stiffness fast tool servo device using a magnetorheological elastomer as a core layer, comprising:

[0048] Flexible mechanism, the present invention uses three types of flexible mechanisms, namely: 1. single straight circular flexible hinge 1, 2. straight beam flexible hinge 201, 3. flexible curved beam 402; the positions of these three flexible mechanisms are distributed as follows: the single straight circular flexible hinge 1 with a guiding function is directly connected to the rigid structure 401 included in the variable stiffness mechanism 4, and is symmetrically distributed on both sides relative to the central axis direction of the tool holder; there are three straight beam flexible hinges 201 in the device, all of which are located at the rear side of the driving component 3 and at the front end of the fine-tuning component 2; in the device, the flexible curved beam 402 with a variable stiffness function is directly connected to the rigid structure 401 included in the variable stiffness mechanism 4, and is directly connected to the tool holder 5;

[0049] The fine-tuning component 2 is located on the rigid base frame 6. There are three groups of them, all of which are located at the rear side of the driving component 3, that is, at the rear side of the first type of piezoelectric ceramics 301, 302 and the second type of piezoelectric ceramics 303. The straight beam flexible hinge 201 in the fine-tuning component is driven by the pre-tightening bolt 202 to fine-tighten the pre-tightening driving component 3.

[0050] The pre-tightening bolt hole in the fine-tuning component is used to install the pre-tightening bolt. Its function is to pre-tighten the straight beam flexible hinge in the fine-tuning component by adjusting the pre-tightening bolt, and then pre-tighten the piezoelectric ceramics in the driving component. By simultaneously fine-tuning and pre-tightening on both sides, it can be ensured that the central axis of the tool holder always coincides with the central axis of the rigid base frame, that is, the structure has good concentricity.

[0051] The piezoelectric ceramic driving components are divided into two categories according to their different distribution positions, and the two categories of driving components have different functions for the variable stiffness fast tool servo device. Among them, the one end of which is located on the rigid structure mainly provides pre-tightening displacement for the flexible curved beam structure, while the one end of which is located on the tool holder mainly provides displacement input for the movement of the tool along the central axis of the tool holder.

[0052] Specifically, the driving component 3 is composed of three groups of piezoelectric ceramics, which can be divided into two categories, wherein the first group of piezoelectric ceramics 301 and the second group of piezoelectric ceramics 302 together constitute the first type of piezoelectric ceramics, one end of the first type of piezoelectric ceramics is located on the rigid structure 401, and the other end is located on the fine-tuning component, which plays a role in pre-tightening the flexible curved beam 402; and the third group of piezoelectric ceramics 303 is the second type of piezoelectric ceramics, one end of the second type of piezoelectric ceramics is located on the tool holder, and the other end is located on the fine-tuning component, which plays a role in driving the tool holder 5 and the tool installed on the tool holder to a predetermined position, so as to further process the workpiece;

[0053] The variable stiffness mechanism 4 is mainly composed of two flexible curved beams 402 and a core magnetorheological elastic body 403, and is fixedly connected to the rigid structure 401 as a whole;

[0054] It also includes a turning tool, which is installed on the turning tool holder. To ensure that the turning tool is firmly fixed on the turning tool holder, at least two screws are used to press the turning tool on the turning tool holder.

[0055] The two parts included in the tool holder 5 and the variable stiffness mechanism 4, namely, the two flexible curved beams 402 and the core layer magnetorheological elastomer 403 are directly connected, and there are four tool mounting holes 501 on the tool holder 5 for mounting the tool;

[0056] The rigid base frame 6 mainly constitutes the structural basis of the variable-rigidity fast-tool servo device, and the construction of other components is based on the design distribution position and size of the rigid base frame 6.

[0057] The single straight circular flexible hinge 1 is symmetrically distributed on both sides relative to the central axis direction of the tool holder 5, with two groups of four on one side and eight on both sides. It mainly plays the role of guiding the displacement input by the driving component 3 and decoupling the front-to-back and left-to-right displacement input; its role is to guide the displacement input by the piezoelectric ceramic and decouple the input of the two types of driving components.

[0058] The variable stiffness component is composed of two flexible curved beams 402 seamlessly sandwiching a magnetorheological elastomer 403, and the magnetorheological elastomer is formed by five magnetorheological elastic sheets of polydimethylsiloxane PDMS mixed with carbonyl iron particles and solidified tightly stacked, and the shape of the magnetorheological elastomer is consistent with the shape of the flexible curved beam. The magnetorheological elastomer is formed by five 1 mm magnetorheological elastic sheets tightly stacked. The magnetorheological elastic sheet is obtained by mixing polydimethylsiloxane PDMS with carbonyl iron particles and fully stirring them, then defoaming them in vacuum, pouring them into a mold, and finally heating and curing them.

[0059] An external magnetic field is used to control the transformation of randomly dispersed carbonyl iron particles in the core magnetorheological elastomer from isotropy to anisotropy, that is, the magnetic particles in the magnetorheological elastomer will form a chain structure along the direction of the solidified magnetic field, thereby changing the stiffness of the magnetorheological elastomer.

[0060] In the embodiment, a method for using a curved beam variable stiffness fast tool servo device using a magnetorheological elastomer as a core layer is as follows:

[0061] 1. The piezoelectric ceramics 3 of the first type of driving components located on both sides produce corresponding elongation due to the application of external voltage, thereby giving the flexible curved beam 402 a corresponding pre-tightening displacement. In order to ensure that the center axis of the tool holder and the center axis of the rigid base have good coincidence, a small pre-tightening force can be applied to the flexible straight beam 201 through the pre-tightening bolts 202 of the fine-tuning mechanism 2, thereby pre-tightening and fine-tuning the piezoelectric ceramics 3 so that the structure has good centering.

[0062] 2. After the flexible curved beam 402 is pre-tightened, the piezoelectric ceramic 3 of the second type of driving component located at the rear side of the tool holder generates corresponding elongation due to the application of external voltage, so that the tool installed at the tool hole 501 on the tool holder 5 reaches the predetermined processing position.

[0063] 3. The flexible curved beam 402 will also be pre-tightened to different degrees by applying different external voltages to the piezoelectric ceramics 3 of the first type of driving components. At this time, the piezoelectric ceramics 3 of the second type of driving components on the rear side of the tool holder produce the same elongation under the same external voltage, but the force at the output end of the tool is different. That is, different output displacements at the output end of the structure correspond to different output forces, that is, the output stiffness of the structure changes, and the working bandwidth of the device is expanded.

[0064] 4. In order to further increase the output stiffness in step 3 and further broaden the output stiffness of the device, based on the principle that stiffness parallel connection can expand stiffness, the flexible curved beam 402 and the magnetorheological elastomer 403 are connected in parallel, that is, a variable stiffness component 4 is made. Under the control of an external magnetic field, the stiffness of the magnetorheological elastomer 403 is changed, thereby affecting the output stiffness of the structure.

[0065] 5. Since the flexible curved beam 402 and the magnetorheological elastomer 403 described in the above steps 3 and 4 are in parallel, the adjustment of the output stiffness of the structure can rely on both the flexible curved beam 402 and the magnetorheological elastomer 403, or on the coordinated changes of the two at the same time, so the output stiffness of the structure can be controlled in real time.

[0066] The above is only a specific implementation of the present invention, but the protection scope of the present invention is not limited thereto. Any modification, equivalent replacement and improvement made by any person skilled in the art within the technical scope disclosed by the present invention and within the spirit and principle of the present invention shall be covered within the protection scope of the present invention. At the same time, the contents not described in detail in this specification belong to the prior art known to those skilled in the art.

Claims

1. A variable stiffness fast tool servo device for a curved beam, characterized in that: It comprises a single straight circular flexible hinge (1), a fine-tuning component (2), a driving component (3), and a variable stiffness mechanism (4); The fine-tuning component (2) comprises a straight beam flexible hinge (201) and a pre-tightening bolt (202); The straight beam flexible hinge (201) is located at the rear side of the driving component (3); The straight beam flexible hinge (201) is fine-tuned and driven by the pre-tightening bolt (202), thereby fine-tuning the pre-tightening driving component (3); The variable stiffness mechanism (4) is composed of a rigid structure (401), a flexible curved beam (402), and a core layer magnetorheological elastic body (403); The single straight circular flexible hinge (1) is directly connected to the rigid structure (401); The flexible curved beam (402) and the core layer magnetorheological elastic body (403) are integrally and directly fixedly connected to the turning tool holder (5).

2. The variable stiffness fast tool servo device for a curved beam according to claim 1, characterized in that: The driving component (3) is composed of three groups of piezoelectric ceramics, which are divided into two categories; the first group of piezoelectric ceramics (301) and the second group of piezoelectric ceramics (302) together constitute the first type of piezoelectric ceramics, the first type of piezoelectric ceramics are located on the rigid structure (401), and play a role in pre-tightening the flexible curved beam (402); the third group of piezoelectric ceramics (303) are the second type of piezoelectric ceramics, the second type of piezoelectric ceramics are located on the tool holder (5), and play a role in driving the tool holder (5) and the tool mounted on the tool holder to a predetermined position.

3. The variable stiffness fast tool servo device for a curved beam according to claim 2, characterized in that: The single straight circular flexible hinge (1) is symmetrically distributed on both sides relative to the central axis direction of the tool holder (5), and plays a role in guiding the displacement input by the driving component (3) and releasing the coupling of the front-to-back and left-to-right displacement input.

4. The variable stiffness fast tool servo device for a curved beam according to claim 1, characterized in that: The variable stiffness mechanism (4) is symmetrically distributed on both sides relative to the central axis direction of the tool holder (5). The flexible curved beam (402) in the single-side variable stiffness mechanism (4) is provided with two pieces, which sandwich the magnetorheological elastic body (403) without any gap.

5. The variable stiffness fast tool servo device for a curved beam according to claim 1, characterized in that: The magnetorheological elastomer is formed by closely stacking magnetorheological elastic sheets formed by solidifying polydimethylsiloxane (PDMS) mixed with carbonyl iron particles, and the shape of the magnetorheological elastomer is consistent with the shape of the flexible curved beam.

6. The variable stiffness fast tool servo device for a curved beam according to claim 1, characterized in that: The fine-tuning components (2) are located on a rigid base frame (6) and are arranged in three groups.

7. The variable stiffness fast tool servo device for a curved beam according to claim 1, characterized in that: Three straight beam flexible hinges (201) are provided, all located at the rear side of the driving component (3) and at the front end of the pre-tightening bolt (202).

8. The variable stiffness fast tool servo device for a curved beam according to claim 6, characterized in that: The rigid base frame (6) constitutes the structural basis of the variable stiffness fast tool servo device, and the construction of the single straight circular flexible hinge (1), the fine adjustment component (2), the driving component (3), and the variable stiffness mechanism (4) components are adapted to the design distribution position and size of the rigid base frame (6).

9. A method for using a curved beam variable stiffness fast tool servo device, characterized in that: The first type of piezoelectric ceramics on both sides generate corresponding elongation due to the application of external voltage, giving the flexible curved beam (402) a corresponding preload displacement; After the flexible curved beam (402) is pre-tightened, the piezoelectric ceramic (3) of the second type of driving component located at the rear side of the tool holder generates a corresponding extension due to the application of an external voltage, so that the tool installed at the tool hole (501) on the tool holder (5) reaches a predetermined processing position; By applying different external voltages to the piezoelectric ceramics (3) of the first type of driving component, the flexible curved beam (402) will be pre-tightened to different degrees; The piezoelectric ceramic (3) of the second type of driving component at the rear side of the tool holder produces the same elongation when the same external voltage is applied; the forces acting on the output end of the tool are different; different output displacements at the output end of the structure correspond to different output forces, and the output stiffness changes; The curved beam (402) and the magnetorheological elastic body (403) are in a parallel relationship, and the output stiffness is regulated by the coordinated changes of the flexible curved beam (402) and the magnetorheological elastic body (403).

10. The method for using the curved beam variable stiffness fast tool servo device according to claim 9, characterized in that: A slight pre-tightening force is applied to the straight beam flexible hinge (201) by fine-tuning the pre-tightening bolt (202), thereby fine-tuning the pre-tightening of the first type of piezoelectric ceramic.

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