CN107328649B - Piezoelectric driving three-jaw bionic micro-size clamping mechanism based on flexible hinge - Google Patents
Piezoelectric driving three-jaw bionic micro-size clamping mechanism based on flexible hinge Download PDFInfo
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- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
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- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L1/00—Measuring force or stress, in general
- G01L1/20—Measuring force or stress, in general by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress
- G01L1/22—Measuring force or stress, in general by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress using resistance strain gauges
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- G—PHYSICS
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
- G01N3/18—Performing tests at high or low temperatures
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- G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- G05D15/00—Control of mechanical force or stress; Control of mechanical pressure
- G05D15/01—Control of mechanical force or stress; Control of mechanical pressure characterised by the use of electric means
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- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0014—Type of force applied
- G01N2203/0016—Tensile or compressive
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- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0058—Kind of property studied
- G01N2203/0069—Fatigue, creep, strain-stress relations or elastic constants
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/02—Details not specific for a particular testing method
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- G01N2203/0254—Biaxial, the forces being applied along two normal axes of the specimen
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/02—Details not specific for a particular testing method
- G01N2203/04—Chucks, fixtures, jaws, holders or anvils
- G01N2203/0482—Chucks, fixtures, jaws, holders or anvils comprising sensing means
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Abstract
The invention relates to a piezoelectric driving three-jaw bionic micro-size clamping mechanism based on a flexible hinge, belonging to the field of precision driving and in-situ testing of micromechanics of materials. The three multi-load piezoelectric drivers with built-in encapsulated piezoelectric stacks are in a 120-degree inner-enveloping annular distribution installation mode, through expansion in a lower flexible hinge moving auxiliary surface and motion transmission by taking an inner layer fulcrum as a revolute pair movement center, a claw toe clamping end adopts a biological non-smooth mechanism and a soil animal claw toe configuration, so that the clamping friction force is increased, the problem of clamping a micro-size component can be solved, and in addition, the micro-clamping mechanism can be combined with a combined supporting unit and a high-temperature loading unit to construct a single-axis and double-axis force field with controllable displacement under a high-temperature service condition, and the single-axis and double-axis mechanical property testing function of the micro-size component is realized. The invention has compact structure and wide application range, can be used in combination with a scanning electron microscope, and provides an effective tool for mechanical property test and characterization of micro-size materials such as carbon fiber.
Description
Technical Field
The invention relates to the field of precision driving and in-situ testing of micromechanics of materials, in particular to instruments in the field of micro-electromechanical systems, and particularly relates to a piezoelectric driving three-jaw bionic micro-size clamping mechanism based on a flexible hinge, which is used for clamping and testing micro-size materials with characteristic sizes below 0.1 mm. The invention can carry out in-situ detection on the tested piece under the mechanical state of uniaxial tensile stress and biaxial tensile stress by being compatible with imaging instruments such as a scanning electron microscope, and the like, provides an effective means for revealing the deformation damage mechanism and the performance evolution rule of micro-size materials such as carbon fibers, and provides test equipment for material characterization and deep understanding of the mechanical properties of the materials.
Background
With the development of technology, submicron and even nanometer precision operation technologies are urgently needed in the fields of ultra-precision machining, microelectronic engineering, biological engineering, nanotechnology and the like. In micro-assembly systems, the micro-gripper system is a critical part of ensuring the reliability and functionality of the entire micromechanical system, which is often tightly linked to micro-assembly, micro-operation, etc. system technologies. The micro-gripper is used as a typical micro-actuator and has wide application in the aspects of micro-mechanical part processing, micro-mechanical assembly, bioengineering and the like.
A complete micro-gripper comprises two parts of driving and transmission, and is usually driven by a piezoelectric stack, wherein the expansion and contraction amount of the micro-gripper is related to the applied voltage, and is less influenced by factors such as ambient temperature, humidity, electromagnetic field, airflow and the like. The transmission link adopts a flexible hinge, which is a novel transmission and supporting mechanism developed in recent years, and the flexible hinge uses the elastic deformation of the weak link to complete the similar hinge function, and has the advantages of small volume, no friction, small movement gap, high resolution and the like. However, in the present case, the micro-gripper using flexible hinges in combination with piezoelectric stacks has the disadvantage that: first, the study of the micro gripper by domestic scholars is mainly focused on structural design and theoretical modeling for realizing the gripping function. Yu Dahai a multipurpose micro-gripper suitable for Inertial Confinement Fusion (ICF) target gripping; hao Yongping proposes a Micro-gripper structure for MEMS (Micro-Electro-Mechanical System) assembly; wang Daihua proposes a piezo-driven micro-gripper and its open-loop displacement characteristics. However, they designed holders only achieve micro-clamping functions, and do not consider how clamping force sensing is integrated into the structure, and cannot detect clamping force of the holder in an operating state. In the micro-clamping process, the micro-clamp device not only needs to complete the clamping operation of the micro-sized object, but also avoids damage or falling off of the micro-sized object in the micro-clamping process. The existing micro-gripper only belongs to open-loop control, and implementation detection in the gripper is not realized, so that the gripper force is predicted and controlled. Secondly, most of today's micro-holders adopting flexible hinges are plane flexible hinge mechanisms, and only have clamping effect, so that micromechanics performance test of materials is difficult to combine with clamping.
In summary, it is necessary to develop a micro-gripper that can integrate micro-sized specimen clamping with material micromechanics testing and can perform closed-loop control of clamping force.
Disclosure of Invention
The invention aims to provide a piezoelectric driving three-jaw bionic micro-size clamping mechanism based on a flexible hinge, which solves the problems that a micro-size test piece below a millimeter level is difficult to clamp, mechanical property research is difficult to carry out on the micro-size test piece in the prior art, and the like. The invention comprises a piezoelectric parallel loading unit, a flexible hinge transmission unit, a bionic clamping end, a clamping force detection unit, a high-temperature loading unit and a combined supporting unit. The invention can realize the prediction and control of clamping force besides clamping test pieces with different sizes by utilizing the advantages of high testing precision, small volume, compact structure, quick response, easy control of output displacement and the like of the piezoelectric driving element and combining the bionic clamping end and the clamping force detection unit. Meanwhile, the high-temperature loading unit and the combined supporting unit can be combined with the piezoelectric driving three-jaw micro-size clamping mechanism to form a single-shaft stress testing platform under the high-temperature service condition. The test platform can be combined with a double-shaft base to form a double-shaft plane stress state test platform under the high-temperature service condition. In addition, the invention has the whole size of only 30 mm multiplied by 26 multiplied by mm multiplied by 16mm, can be placed in a scanning electron microscope cavity and used together with characterization instruments such as a scanning electron microscope, truly realizes in-situ test, and provides an effective means for revealing deformation damage mechanisms and performance evolution rules of micro-size materials such as carbon fibers.
The above object of the present invention is achieved by the following technical solutions:
the piezoelectric driving three-jaw bionic micro-size clamping mechanism based on the flexible hinge comprises a piezoelectric loading unit, a flexible hinge transmission unit, a bionic clamping unit, a clamping force detection unit, a high-temperature loading unit and a detachable supporting unit, wherein a flexible hinge revolute pair moving end 3, a flexible hinge spherical pair moving end 4, a flexible hinge base 5 and a jaw toe clamping end in the flexible hinge transmission unit are integrated into a whole, a groove with the same width as that of a multi-load packaged piezoelectric stack 1 is arranged in the flexible hinge base 5, and the multi-load packaged piezoelectric stack 1 is embedded in the groove and is pre-tightened through a piezoelectric stack pre-tightening block 2; the flexible hinge base 5 is rigidly connected with the combined base 7 through an M3 bolt 6 and an M3 nut 10, and the double-shaft base 8 is rigidly connected with the combined base 7 through an M2 bolt 9; the halogen heating lamp 14 in the high-temperature loading unit is rigidly connected with the combined base 7 in a threaded connection mode;
the piezoelectric loading unit comprises three multi-load piezoelectric drivers, three flexible hinge spherical pair moving ends 4 and three flexible hinge revolute pair moving ends 3, and each multi-load piezoelectric driver consists of a piezoelectric stack pre-tightening block 2 and a multi-load packaged piezoelectric stack 1; three multi-load piezoelectric drivers are distributed in a 120-degree inner envelope type ring shape and are arranged in clamping grooves of the flexible hinge base 5; when no voltage is applied to the multi-load packaged piezoelectric stack 1, the multi-load packaged piezoelectric stack is under the action of the piezoelectric stack pre-tightening block 2 with adjustable thickness and is in a compressed state; when voltage is applied, the piezoelectric stack is axially elongated, and the cuboid multi-load packaged piezoelectric stack 1 has an output displacement self-detection function;
the flexible hinge transmission unit is: the output displacement of the multi-load packaged piezoelectric stack 1 is transmitted to the claw-toe clamping end through the in-plane expansion of the movable end of the revolute pair of the lower flexible hinge 17 and the bending of the compression bar taking the movable end 4 of the flexible hinge spherical pair of the inner flexible hinge 16 as a fulcrum; the three flexible hinge revolute pair moving ends 2, the three flexible hinge spherical pair moving ends 4 and the three claw toe clamping ends are annularly and symmetrically distributed at 120 degrees, so that the superposition of a clamping axis and a material axis is ensured;
the bionic clamping unit is three claw-toe clamping ends, each claw-toe clamping end consists of a biological non-smooth surface 11 and a claw-toe configuration 12 of a soil animal, and output displacement of the multi-load packaged piezoelectric stack 1 is transmitted to the claw-toe clamping ends through a flexible hinge revolute pair moving end 3 and a flexible hinge spherical pair moving end 4, so that the claw-toe clamping ends deform to clamp a test piece; the biological non-smooth surface 11 and the claw toe configuration 12 of the claw toe clamping end increase friction between the claw toe clamping end and the clamped object, so that the clamping of a small-sized test piece which is difficult to clamp is realized;
the clamping force detection unit is: the resistance strain gauge 15 is directly adhered to the claw toe structure 12 at the claw toe clamping end, when the claw toe structure 12 is contacted with the clamped micro-test piece 13 to realize clamping, the deformation of the tip end of the claw toe structure 12 is the maximum, namely the position of the force sensing unit, and the strain of the resistance strain gauge 15 directly reflects the clamping force; the relation between the input voltage of the piezoelectric driver, the clamping force and the strain of the force sensor unit is respectively determined by a calibration method, so that the relation between the driving voltage and the clamping force can be obtained, and the clamping force can be conveniently predicted and controlled.
The detachable support unit consists of a combined base 7, a double-shaft base 8 and a bolt 9, and when the combined base 7 is singly and rigidly connected with the flexible hinge base 5 through the bolt 6 and the nut 10, the single-shaft mechanical test function of the material is realized; the double-shaft base 8 is connected with the combined base 7 through a bolt 9, and is connected with the flexible hinge base 5 through a 6 bolt and a nut 10, so that a double-shaft mechanical testing function is realized;
the high-temperature loading unit comprises a combined base 7 and a halogen heating lamp 14, the center of the combined base 7 is provided with an annular groove structure, the halogen heating lamp 14 is directly embedded in the center of the combined base 7, and the focus of the light source is the center of the clamped micro-test piece 13.
The multi-load packaged piezoelectric stack 1 is distributed in a 120-degree inner enveloping type ring, displacement output by the multi-load packaged piezoelectric stack is expanded in the plane of the moving end of the revolute pair of the lower flexible hinge 17 under the action of a voltage signal, and is transmitted to the claw-toe clamping end through compression rod bending taking the moving end 4 of the spherical pair of the flexible hinge of the inner flexible hinge 16 as a fulcrum, so that the claw-toe clamping end rotates in the axial direction and retreats close to the flexible hinge base 5; based on driving voltages with different magnitudes, the three multi-load packaged piezoelectric stacks 1 realize various combination forms of axial extension motions, and correspond to displacements of different forms of claw-toe clamping ends; furthermore, clamping of the tested micro-test pieces with different diameters is realized.
The claw toe clamping end is provided with a biological non-smooth surface 11, spherical crown-shaped convex hulls are distributed on the surface of the claw toe clamping end, so that the clamping resistance is increased, the service life of the clamping end is remarkably prolonged, and a small-size test piece is clamped more tightly. The top of the claw toe clamping end uses the claw toe configuration 12 of the soil animal, and when the output motion of the multi-load packaged piezoelectric stack 1 is transmitted to the claw toe clamping end, the claw toe configuration 12 at the top increases the clamping stability; and the three claw toe clamping ends are distributed symmetrically in 120-degree space, when the same voltage signal is input to the multi-load packaged piezoelectric stack 1, the movement modes are consistent, the coincidence of the center of a test piece and the geometric center of the device during clamping is ensured, and the centering is ensured.
The clamping force detection unit directly adheres the resistance strain gauge 15 to the maximum deformation position of the tip of the claw toe configuration 12 of the bionic clamping end, and the relation between the driving voltage and the clamping force is determined through calibration, so that the prediction and the control of the clamping force are realized; in the micro-clamping process, the clamping operation of the micro-sized object is completed, and damage or falling of the micro-sized object in the micro-clamping process is avoided.
The combined base 7 is rigidly connected with the flexible hinge base 5 through an M3 bolt 6 and an M3 nut 10, so that uniaxial mechanical test is realized; when the output displacement of the multi-load packaged piezoelectric stack 1 is transmitted to the clamping end of the claw toe, the motion mode of the multi-load packaged piezoelectric stack not only is clamping close to a central shaft, but also has retreating motion close to the flexible hinge base 5, and the retreating motion corresponds to clamping and axial stretching of a test piece; the combined base 7 can be rigidly connected with the double-shaft base 8 through M2 bolts 9, so that double-shaft mechanical testing is realized.
The high-temperature loading unit is integrated in the combined base 7, the halogen heating lamp 14 is directly embedded in the annular groove at the center of the combined base 7, and the focal point of the light source is just opposite to the center of the clamped micro-test piece 13, so that a mechanical property test platform under the high-temperature service condition is constructed.
The invention has the beneficial effects that: the device has a exquisite structure, the size of the whole device is only 30 mm multiplied by 26 mm multiplied by 16mm, and the clamping of a micro test piece with the characteristic size diameter below 0.1mm can be realized by precisely driving a flexible hinge through piezoelectric stack driving. The bionic clamping end can be used for improving the stability of clamping, so that the damage or falling of the micro object in the micro clamping process is avoided while the clamping operation of the micro object is finished. The high-temperature loading unit and the combined supporting unit can be integrated, and the micro-mechanical mechanism of the material in a high-temperature service environment and plane stress state can be researched by being compatible with imaging instruments and equipment such as a scanning electron microscope, so that a clamping method is provided for knowing and revealing the mechanical property of the material and improving the service reliability and stability of an engineering structure.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate and explain the invention and together with the description serve to explain the invention.
FIG. 1 is a schematic view of the overall appearance structure of the present invention;
FIG. 2 is a schematic drawing of a uniaxially stretched form of the present invention;
FIG. 3 is an overall schematic view of a clamping mechanism according to the present invention;
FIG. 4 is an overall schematic view of the flexible hinge of the present invention;
FIG. 5 is a schematic diagram of a bionic clamping end according to the present invention;
FIG. 6 is a schematic diagram of a loading mode of the present invention;
fig. 7 is a schematic diagram of the flexible hinge transmission of the present invention.
In the figure: 1. the multi-load packaged piezoelectric stack 2, a piezoelectric stack pre-tightening block 3, a flexible hinge revolute pair moving end 4, a flexible hinge spherical pair moving end 5, a flexible hinge base 6, an M3 bolt 7, a combined base 8, a double-shaft base 9, an M2 bolt 10, an M3 nut 11, a biological non-smooth surface 12, a claw toe configuration 13, a clamped micro-test piece 14, a halogen heating lamp 15 and a resistance strain gauge; 16. an inner flexible hinge; 17. a lower flexible hinge.
Detailed Description
The details of the present invention and its specific embodiments are further described below with reference to the accompanying drawings.
Referring to fig. 1 to 7, the flexible hinge-based piezoelectric driving three-jaw bionic micro-size clamping mechanism comprises a piezoelectric loading unit, a flexible hinge transmission unit, a bionic clamping unit, a clamping force detection unit, a high-temperature loading unit and a detachable supporting unit, wherein a regular groove is processed on a flexible hinge base 5, the regular groove is matched with the size of a multi-load packaged piezoelectric stack 1, the multi-load packaged piezoelectric stack 1 is embedded into the groove of the flexible hinge base 5, and the pre-tightening is performed through a pre-tightening block 2 with adjustable thickness, so that the multi-load packaged piezoelectric stack 1 is ensured to bear compression load. The voltage is output by the piezoelectric stack driver to the multi-load packaged piezoelectric stack 1, so that the multi-load packaged piezoelectric stack 1 has displacement output. The flexible hinge base 5 remains fixed and the output displacement of the multi-load packaged piezoelectric stack 1 is transferred to the toe-gripping lever by in-plane expansion of the lower flexible hinge 17 revolute pair moving end 3 in direct contact therewith. The three claw toe clamping rods are annularly and symmetrically distributed at 120 degrees in space and are connected with each other by two cylindrical rods of the inner flexible hinge 16, and two groups of conical flexible hinge spherical pair moving ends 4 are machined on each cylindrical rod. When the motion is transferred to the claw-toe clamping rod, the center of the spherical pair moving end of the inner flexible hinge 16 is used as a motion fulcrum, the cylindrical rod of the inner flexible hinge 16 is bent under the action of bending moment, the claw-toe clamping end is close to a test piece, and the tested micro test piece 13 is clamped by the biological non-smooth surface 11 processed on the claw-toe clamping end and the claw-toe configuration 12 and has a rollback function close to the flexible hinge base 5. The piezoelectric driving three-jaw bionic micro-size clamping mechanism based on the flexible hinge, which can realize clamping and rollback movement, can be connected with the combined base 7 through the M3 bolt 6 to form a mechanical testing platform capable of carrying out uniaxial tension experiments on the tested micro test piece 13. If the plane stress is to be tested, the formed uniaxial tensile test platform can be combined with the biaxial base 8 through the M2 bolts 9 to form the biaxial mechanical property test platform with four clamping ends forming 90-degree included angles in the plane.
The piezoelectric loading unit comprises three multi-load piezoelectric drivers, three revolute pair moving ends 3 and three spherical pair moving ends 4, wherein the flexible hinge revolute pair moving ends 3, the flexible hinge base 5, the flexible hinge spherical pair moving ends 4 and the claw toe clamping ends are integrated. The flexible hinge base 5, i.e. the rigid part of the flexible hinge, is machined with a regular groove structure, and the multi-load packaged piezoelectric stack 1 is mounted in the groove in the flexible hinge base 5 by means of an embedded manner. The multi-load packaged piezoelectric stack 1 is preloaded through the thickness-adjustable preloading block 2, so that the multi-load packaged piezoelectric stack 1 is ensured to bear compression load. The flexible part in the flexible hinge rotating unit, namely the flexible hinge revolute pair moving end 3 and the flexible hinge spherical pair moving end 4, can be cut through the focused ion beam, so that the flexible part can be deformed as required, and the output displacement of the multi-load packaged piezoelectric stack 1 is amplified linearly in a constant ratio, so that the clamping movement of the claw-toe clamping end to a test piece is realized. The flexible hinge base 5 is rigidly connected to the modular base 7 by means of bolts 6 by means of threaded connections. The double-shaft base 8 can be rigidly connected with the combined base 7 through a threaded connection with the M2 bolt 9.
The bionic clamping unit comprises three bionic clamping claws, wherein each bionic clamping claw consists of a biological non-smooth surface 11 and a claw toe configuration 12. The bio-non-smooth surface 11 has a convex hull shape non-smooth shape, and the convex hull diameter gradually increases from the clamping end to the flexible hinge base end, so that the contact area between the clamping end and the test piece is increased compared with the surface of the clamping end without special treatment, and the clamping is firmer. The toe configuration 12 evolved from a typical soil animal toe configuration to ensure a tighter, more reliable grip of the specimen by the gripping end. The three bionic clamping claws are distributed in a 120-degree inner envelope annular mode, have self-centering performance, and ensure that the axis of a clamped test piece coincides with the axis of the whole clamping mechanism.
The clamping force detection unit comprises a claw toe structure 12, a clamped micro-test piece 13 and a resistance strain gauge 15, wherein the resistance strain gauge 15 can be directly adhered to the claw toe structure 12 at the bionic clamping end, when the claw toe structure 12 is contacted with the clamped micro-test piece 13 to realize clamping, the deformation of the tip end of the claw toe structure 12 is the largest, the position is the position of the force sensing unit, and the strain of the resistance strain gauge 15 directly reflects the clamping force. The relation between the input voltage of the piezoelectric driver, the clamping force and the strain of the force sensor unit is respectively determined by a calibration method, so that the relation between the driving voltage and the clamping force can be obtained, and the clamping force can be conveniently predicted and controlled. In the micro-clamping process, the clamping operation of the micro-sized object is completed, and damage or falling of the micro-sized object in the micro-clamping process is avoided.
The combined supporting unit consists of an M3 bolt 6, an M2 bolt 9, an M3 nut 10, a combined base 7 and a double-shaft base 8. Two parallel symmetrical end faces are arranged in the combined base 7, a threaded hole is formed in the center of the end faces, a through hole is formed in the center of the flexible hinge base 5, and the combined base 7 can be fixedly connected with the flexible hinge base 5 through an M3 bolt 6. After the output displacement of the multi-load packaged piezoelectric stack 1, the bionic clamping claw performs retreating movement besides clamping a test piece through displacement transmission of the flexible hinge revolute pair moving end 3 and the flexible hinge spherical pair moving end 4, and the combined base 7 provides thrust for supporting the flexible hinge transmission unit at the moment, so that the clamped micro test piece 13 is subjected to the action of the tensile force, and a mechanical experiment platform capable of performing uniaxial tensile test on the micro-sized test piece is formed. Besides, by using the same principle, the whole mechanism can be fixedly connected with the double-shaft base 8 through the M2 bolt 9 to form an experimental platform capable of carrying out double-shaft mechanical experiment to study the plane stress state of the material.
The high-temperature loading unit comprises a combined base 7 and a halogen heating lamp 14, an annular groove structure is formed in the center of the combined base 7, the halogen heating lamp 14 can be directly embedded in the center of the combined base 7, and a light source focus is the center of the clamped micro test piece 13, so that a mechanical property testing platform under the high-temperature service condition is formed.
Referring to fig. 1 to 7, the invention relates to a flexible hinge-based piezoelectric driving three-jaw bionic micro-size clamping mechanism, the overall size of a testing device is about 30 mm ×26 mm ×16mm, three multi-load piezoelectric drivers of built-in packaged piezoelectric stacks are in a 120-degree inner-envelope annular distribution installation form, and the axial extension motion of the three multi-load piezoelectric drivers under different time sequence voltages corresponds to different clamping diameters of a clamped test piece through expansion in a lower flexible hinge moving auxiliary surface and motion transmission by taking an inner fulcrum as a revolute pair motion center. The bionic clamping end adopts a biological non-smooth mechanism and a soil animal claw configuration, so that the clamping friction force is increased, and the difficulty of clamping a micro-size component can be solved. The clamping force detection unit can detect the clamping force of the clamping end on the test piece, and damage to the test piece is avoided. In addition, the micro-clamping mechanism can be combined with the combined supporting unit and the high-temperature loading unit to construct a single-axis and double-axis force field with controllable displacement under the high-temperature service condition, so that the single-axis and double-axis mechanical property testing function of the micro-size component is realized. The invention has compact structure and wide application range, can be used in combination with a scanning electron microscope, and provides an effective tool for mechanical property test and characterization of micro-size materials such as carbon fiber. The components and specific models involved in the invention are as follows: the model of the multi-load packaged piezoelectric stack 1 is PSt 150/2 multiplied by 3/5, the ceramic size is 2 multiplied by 3 multiplied by 5mm, the rigidity is 45N/mu m, the resonance frequency is 150kHz, the maximum thrust is 300N, and the nominal displacement is 5 mu m. The pretension block 7 adopts a linear cutting processing mode, the thickness of the pretension block is adjustable and is 1mm-1.2mm, pretension of the multi-load packaged piezoelectric stack 9 can be realized, and the maximum pretension force can reach 100N. The flexible hinge revolute pair moving end 4, the flexible hinge spherical pair moving end 5 and the flexible hinge base 5 are integrated, and the positioning surface and the contact surface of the flexible hinge revolute pair moving end 4, the flexible hinge spherical pair moving end and the flexible hinge base 5 are polished and flattened. The conical surface processing of the flexible hinge spherical pair moving end 5 is divided into two working procedures, namely precise numerical control boring processing and quick cutter servo processing. The combined base 7 and the double-shaft base 8 adopt a linear cutting processing mode, and the positioning surface and the contact surface of the combined base 7 and the double-shaft base are polished and flattened. The biological non-smooth surface 11 has a convex hull structure with the size of 50-1 mu m and the size of change, adopts a cold gas dynamic spraying mode, takes compressed gas as accelerating gas, drives 65Mn powder particles to strike the bionic clamping end surface at room temperature and supersonic speed, and enables metal particles to be subjected to strong plastic deformation to be deposited to form a coating. The toe structure 12 adopts a focused ion beam cutting method because of its tiny tip structure. The halogen heating lamp 14 is G3, and the maximum heating temperature can reach 1200 ℃. The type of the resistance strain gauge is Japanese co-mingled KHCD type high-temperature strain gauge, and can stably work in a high-temperature environment of 850 ℃.
In the specific test process, if only the clamping of the micro-sized test piece is realized, three multi-load packaged piezoelectric stacks 1 are embedded into the clamping grooves of the flexible hinge base 5, and the pre-tightening block 2 is placed between the three piezoelectric stacks 1 to realize pre-tightening of the multi-load packaged piezoelectric stacks 1. The flexible hinge base 5 is then mounted to the fixed platform by means of the M3 bolts 6 and M3 nuts 10. 100V voltage is input to the multi-load packaged piezoelectric stack 1, and the generated displacement is expanded in the plane of the flexible hinge revolute pair moving end 3 and rotated by taking the flexible hinge spherical pair moving end 4 as a fulcrum, so that the bionic clamping end clamps the clamped micro-test piece 13. The resistance strain gauge 15 adhered to the claw toe structure 12 realizes real-time monitoring of clamping force, and damage or falling off of a tiny object in the micro-clamping process is avoided.
If the mechanical performance test on the clamped micro-test piece 13 under the high-temperature service condition is to be realized, the installed clamping mechanisms are integrally connected with the combined base 7 through the M3 bolts 6 and the M3 nuts 10, the two clamping mechanisms are symmetrically installed on the opposite surfaces, the voltage is input to the multi-load piezoelectric stack driver 1, the rollback motion is synchronously realized in the clamping process, and therefore the uniaxial mechanical performance test on the clamped micro-test piece 13 is realized. The halogen heating lamp 14 is embedded in the annular groove at the center of the combined base 7, and 220V voltage is applied to the halogen heating lamp 14, so that a stable temperature field is realized.
If the purpose of testing the mechanical properties of the biaxial plane of the clamped micro-test piece 13 under the high-temperature service condition is to be achieved, the clamped micro-test piece 13 is placed in an installed uniaxial mechanical test platform, the installed clamping mechanism is integrally connected with the biaxial base 8 through threaded connection, the biaxial base 8 is then connected with the combined base 7 in the installed uniaxial mechanical test platform through the M2 bolt 9, and the two ends of the biaxial test piece, which are not clamped, are integrally coaxial with the clamping mechanism installed on the biaxial base 8 during installation. After the installation, the biaxial mechanical property test under the high-temperature service condition can be realized.
The above description is only a preferred example of the present invention and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. of the present invention should be included in the protection scope of the present invention.
Claims (6)
1. A piezoelectric driving three-jaw bionic micro-size clamping mechanism based on a flexible hinge is characterized in that: the device comprises a piezoelectric loading unit, a flexible hinge transmission unit, a bionic clamping unit, a clamping force detection unit, a high-temperature loading unit and a detachable supporting unit, wherein a flexible hinge revolute pair moving end (3), a flexible hinge spherical pair moving end (4), a flexible hinge base (5) and a claw toe clamping end in the flexible hinge transmission unit are integrated into a whole, a groove with the same width as a multi-load packaged piezoelectric stack (1) is arranged in the flexible hinge base (5), and the multi-load packaged piezoelectric stack (1) is embedded in the groove and is pre-tightened through a piezoelectric stack pre-tightening block (2); the flexible hinge base (5) is rigidly connected with the combined base (7) through an M3 bolt (6) and an M3 nut (10), and the double-shaft base (8) is rigidly connected with the combined base (7) through an M2 bolt (9); the halogen heating lamp (14) in the high-temperature loading unit is rigidly connected with the combined base (7) in a threaded connection mode;
the piezoelectric loading unit comprises three multi-load piezoelectric drivers, three flexible hinge spherical pair moving ends (4) and three flexible hinge revolute pair moving ends (3), and each multi-load piezoelectric driver consists of a piezoelectric stack pre-tightening block (2) and a multi-load packaged piezoelectric stack (1); three multi-load piezoelectric drivers are distributed in a 120-degree inner envelope type ring shape and are arranged in clamping grooves of the flexible hinge base (5); when no voltage is applied to the multi-load packaged piezoelectric stack (1), the piezoelectric stack is under the action of the piezoelectric stack pre-tightening block (2) with adjustable thickness and is in a compression state; when voltage is applied, the piezoelectric stack is axially elongated, and the cuboid multi-load packaged piezoelectric stack (1) has an output displacement self-detection function;
the flexible hinge transmission unit is: the output displacement of the multi-load packaged piezoelectric stack (1) is transmitted to the claw-toe clamping end through the in-plane expansion of the moving end of the revolute pair of the lower flexible hinge (17) and the bending of the compression bar taking the moving end (4) of the spherical pair of the flexible hinge of the inner flexible hinge (16) as a fulcrum; the three flexible hinge revolute pair moving ends (3), the three flexible hinge spherical pair moving ends (4) and the three claw toe clamping ends are annularly and symmetrically distributed at 120 degrees, so that the superposition of a clamping axis and a material axis is ensured;
the bionic clamping unit is three claw-toe clamping ends, each claw-toe clamping end consists of a biological non-smooth surface (11) and a claw-toe configuration (12) of a soil animal, and output displacement of the multi-load packaged piezoelectric stack (1) is transmitted to the claw-toe clamping ends through a flexible hinge revolute pair moving end (3) and a flexible hinge spherical pair moving end (4), so that the claw-toe clamping ends deform to clamp a test piece; the biological non-smooth surface (11) and the claw toe configuration (12) of the claw toe clamping end increase friction between the claw toe clamping end and the clamped object, so that the clamping of a small-sized test piece which is difficult to clamp is realized;
the clamping force detection unit is: the resistance strain gauge (15) is directly adhered to the claw toe structure (12) at the claw toe clamping end, when the claw toe structure (12) is contacted with the clamped micro-test piece (13) to realize clamping, the deformation of the tip of the claw toe structure (12) is the maximum, namely the position of the force sensing unit, and the strain of the resistance strain gauge (15) directly reflects the clamping force;
the detachable support unit consists of a combined base (7), a double-shaft base (8) and an M2 bolt (9), and when the combined base (7) is separately and rigidly connected with the flexible hinge base (5) through the M3 bolt (6) and the M3 nut (10), the single-shaft mechanical test function of the material is realized; the double-shaft base (8) is connected with the combined base (7) through an M2 bolt (9), and is connected with the flexible hinge base (5) through an M3 bolt (6) and an M3 nut (10), so that a double-shaft mechanical test function is realized;
the high-temperature loading unit comprises a combined base (7) and a halogen heating lamp (14), an annular groove structure is formed in the center of the combined base (7), the halogen heating lamp (14) is directly embedded in the center of the combined base (7), and the focus of the light source is the center of the clamped micro-test piece (13).
2. The flexible hinge-based piezoelectric driven three-jaw bionic micro-size clamping mechanism according to claim 1, wherein: the multi-load packaged piezoelectric stack (1) is in 120-degree inner-enveloping annular distribution, displacement output by the multi-load packaged piezoelectric stack is expanded in the plane of a movable end of a revolute pair of a lower flexible hinge (17) under the action of a voltage signal, and is transmitted to a claw-toe clamping end through compression rod bending taking a movable end (4) of a flexible hinge spherical pair of an inner flexible hinge (16) as a fulcrum, so that the claw-toe clamping end is finally rotated in the axial direction and retreated to be close to a flexible hinge base (5); based on driving voltages with different magnitudes, the three multi-load packaged piezoelectric stacks (1) realize various combination forms of axial elongation motions, and correspond to displacements of different forms of claw toe clamping ends; furthermore, clamping of the tested micro-test pieces with different diameters is realized.
3. The flexible hinge-based piezoelectric driven three-jaw bionic micro-size clamping mechanism according to claim 1, wherein: the claw-toe clamping end is provided with a biological non-smooth surface (11), spherical crown-shaped convex hulls are distributed on the surface of the claw-toe clamping end, the claw-toe configuration (12) of a soil animal is applied to the top of the claw-toe clamping end, and when the output motion of the multi-load packaged piezoelectric stack (1) is transmitted to the claw-toe clamping end, the claw-toe configuration (12) at the top of the claw-toe clamping end increases the clamping stability; and the three claw toe clamping ends are distributed symmetrically in 120-degree space, when the same voltage signal is input to the multi-load packaged piezoelectric stack (1), the movement modes are consistent, the coincidence of the center of a test piece and the geometric center of the device during clamping is ensured, and the centering is ensured.
4. The flexible hinge-based piezoelectric driven three-jaw bionic micro-size clamping mechanism according to claim 1, wherein: the clamping force detection unit directly adheres the resistance strain gauge (15) to the maximum deformation position of the tip of the claw toe configuration (12) of the bionic clamping end, and the relation between the driving voltage and the clamping force is determined through calibration, so that the prediction and the control of the clamping force are realized; in the micro-clamping process, the clamping operation of the micro-sized object is completed, and damage or falling of the micro-sized object in the micro-clamping process is avoided.
5. The flexible hinge-based piezoelectric driven three-jaw bionic micro-size clamping mechanism according to claim 1, wherein: the combined base (7) is rigidly connected with the flexible hinge base (5) through an M3 bolt (6) and an M3 nut (10), so that a uniaxial mechanical test is realized; when the output displacement of the multi-load packaged piezoelectric stack (1) is transmitted to the clamping end of the claw toe, the motion mode of the multi-load packaged piezoelectric stack is not only clamping close to a central shaft, but also retreating motion close to a flexible hinge base (5), and the retreating motion corresponds to clamping and axial stretching of a test piece; the combined base (7) can be rigidly connected with the double-shaft base (8) through an M2 bolt (9) to realize double-shaft mechanical test.
6. The flexible hinge-based piezoelectric driven three-jaw bionic micro-size clamping mechanism according to claim 1, wherein: the high-temperature loading unit is integrated in the combined base (7), the halogen heating lamp (14) is directly embedded in the annular groove at the center of the combined base (7), and the light source focus is just opposite to the center of the clamped micro test piece (13), so that a mechanical property test platform under the high-temperature service condition is constructed.
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