Piezoelectric driving high-bandwidth linear vibration table and assembling method thereof

Abstract

This invention discloses a piezoelectric-driven high-bandwidth linear vibration table and its assembly method, comprising: a base, including a base plate, a boss located in the center of the base plate, a central threaded through hole, and a plurality of piezoelectric stack support blocks connected by a first flexible hinge around the boss; an integrated flexible hinge guide rail, including a central square motion platform, flexible hinge units symmetrically arranged on the four outer sides of the motion platform, and four outer fixed walls, the fixed walls being connected to the base plate of the base; a piezoelectric stack, the lower end of which is connected to the upper part of the piezoelectric stack support block, and the upper end of which is connected to the motion platform of the integrated flexible hinge guide rail; a wedge-shaped adjusting block located in the gap between the boss and the piezoelectric stack support block; a disc spring assembly located in the groove at the center of the top of the motion platform; a preload rod, the lower end of which is threaded to the base, and the upper end of which preloads the disc spring assembly through a flange; and a locking screw, the external thread of which engages with the internal thread of the lower end of the preload rod and locks the preload rod through a conical surface. The linear vibration table proposed in this invention has high precision, high bandwidth, large load-bearing capacity, compact structure, few parts, and is easy to process, manufacture and assemble.

Description

Technical Field

[0001] This invention relates to the field of precision vibration excitation technology, and in particular to a piezoelectric-driven high-bandwidth linear vibration table and its assembly method. Background Technology

[0002] High-frequency linear vibration tables are mainly used for the excitation and measurement of linear vibrations at high frequencies, micrometer levels, and even smaller amplitudes, and have important applications in inertial navigation testing, high-performance accelerometer calibration, and high-frequency service environment simulation. However, to achieve high-bandwidth (20kHz and above) precision (distortion less than 5%) linear vibration, no mature products have yet been found. Patent application number 201710295806.1 discloses a piezoelectric high-frequency vibration table that uses two sets of piezoelectric stacks with the same amplitude but opposite phase, coaxially mounted as a single-leg excitation, and further extends it to a multi-leg parallel excitation platform. This structure has the following limitations:

[0003] 1) The preload is provided directly by the screw tension of a single leg. The preload stiffness is too large, which weakens the output amplitude of the piezoelectric stack.

[0004] 2) If the load space of this structure is to be expanded, multiple legs need to be connected in parallel. Each leg is pre-tightened by a screw, making it difficult to achieve consistent amplitude and affecting the vibration output accuracy.

[0005] 3) When bearing a large load, this structure is difficult to obtain a high system bandwidth because the lateral stiffness is entirely provided by the piezoelectric stack.

[0006] 4) The vibration platform of this structure is placed between the upper and lower half of the support legs, which limits the size of the load-bearing space. Summary of the Invention

[0007] To address the aforementioned technical problems, the present invention aims to provide a piezoelectric-driven high-bandwidth linear vibration table and its assembly method, which can achieve vibration excitation and measurement with high bandwidth, high precision, large load capacity, and micron-level amplitude, and has a compact structure, few parts, convenient assembly, and high reliability.

[0008] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0009] A piezoelectric-driven high-bandwidth linear vibration table includes: a base, an integrated flexible hinged guide rail, a piezoelectric stack, a wedge-shaped adjustment block, a disc spring assembly, a preload rod, and a locking screw.

[0010] The base includes: a base plate, a boss, a threaded through hole, a piezoelectric stack support block, and a first flexible hinge. The boss is located at the upper center of the base, the threaded through hole is located at the center of the boss, and the piezoelectric stack support block is provided on the four sides of the boss by means of slotting. The piezoelectric stack support block is connected to the boss through the first flexible hinge.

[0011] The integrated flexible hinge guide rail includes: a central square motion platform, flexible hinge units symmetrically arranged on the four outer sides of the motion platform, and four outermost fixed walls. A circular groove is provided in the center of the top of the motion platform, and the center and lower side of the motion platform are cavities. Through slots are opened on the four sides of the integrated flexible hinge guide rail. The integrated flexible hinge guide rail is fitted onto the base and is fixedly connected to the perimeter of the base plate through the fixed walls.

[0012] The piezoelectric stack is placed on top of the support block of the base.

[0013] The wedge-shaped adjustment block includes a stationary wedge and a moving wedge. After the inclined surface of the stationary wedge and the inclined surface of the moving wedge are engaged, the whole block is placed in the gap between the boss of the base and the piezoelectric stack support block.

[0014] The disc spring assembly is placed within the groove of the integrated flexible hinge guide rail.

[0015] The preload rod is connected from top to bottom to the threaded through hole in the center of the base through its lower external thread, and the flange at the upper end of the preload rod is in pressure contact with the disc spring assembly.

[0016] The locking screw is screwed into the internal thread at the lower end of the preload rod from bottom to top via the thread.

[0017] Furthermore, the flexible hinge unit of the integrated flexible hinge guide rail is a flexible hinge with a thick middle and thin ends, and the flexible hinge units on each side are distributed in two arrays at the upper and lower ends.

[0018] Furthermore, the motion platform of the integrated flexible hinge guide rail has a large top thickness and is designed to be lightweight, thereby increasing the top bending stiffness while reducing the mass of the motion platform. The top surface of the motion platform is higher than the flexible hinge units on the four sides and the outer fixed wall, and mounting screw holes for fixing the load are opened on the four sides of the top surface.

[0019] Furthermore, the upper part of the preload rod has a hollow structure to reduce the cantilever mass.

[0020] Furthermore, the lower external thread of the preload rod has an internal thread, and the lower end of the internal thread has a conical surface. The conical surface mates with the conical surface of the locking screw. The lower threaded section of the preload rod has a slot from bottom to top. After the preload rod is tightened onto the base by the step on its lower side, the locking screw is screwed into the preload rod from bottom to top. Due to the wedge-shaped force transmission effect of the conical surface and the elastic deformation of the slot, the thread engagement between the preload rod and the base is tighter, which plays a role in preventing loosening.

[0021] Furthermore, the support block, the first flexible hinge, the piezoelectric stack, and the wedge-shaped adjustment block are arranged in a symmetrical circular array around the axis of the base. The number of arrays can be two, six (under the condition of eliminating interference), or others. Preferably, the number of arrays in this invention is four.

[0022] This invention also provides an assembly method for a piezoelectrically driven high-bandwidth linear vibration table, the specific steps of which are as follows:

[0023] 1) Place each of the piezoelectric stacks and each of the wedge-shaped adjustment blocks in the corresponding positions of the base;

[0024] 2) Adjust each of the wedge-shaped adjustment blocks so that the upper end face of each of the piezoelectric stacks is at the same height relative to the upper surface of the base plate;

[0025] 3) Install the integrated flexible hinge guide rail;

[0026] 4) The pre-tensioned rod is used to press the calibrated disc spring assembly into the groove of the integrated flexible hinge guide rail with a preset compression amount (the preset compression amount is adjusted according to the amplitude and bandwidth requirements (a larger compression amount results in a smaller amplitude and higher bandwidth)).

[0027] 5) To achieve higher vibration accuracy and bandwidth, strain gauges can be attached to the sides of each piezoelectric stack to monitor the vertical strain changes of each piezoelectric stack before and after the pre-tightening rod is tightened. If the strain difference is large, the wedge-shaped adjustment block can be adjusted a second time through the slot on the side of the integrated flexible hinge guide rail to make the pre-tightening force of each piezoelectric stack more uniform;

[0028] 6) Screw the locking screw into the lower end of the preload rod to prevent loosening.

[0029] Due to the application of the above technical solution, the beneficial effects of the present invention are as follows:

[0030] 1) This invention, through an integrated flexible hinge guide structure, increases the horizontal (lateral and longitudinal) stiffness and torsional stiffness of the motion platform, while fully releasing the vertical motion stiffness of the platform. This makes the first-order vibration mode of the vibration table an axial piezoelectric stack expansion vibration mode, thereby obtaining a large vibration bandwidth. During assembly and operation, this structure allows the piezoelectric stack to bear only axial loads, freeing it from horizontal loads, thus preventing shear failure. Furthermore, this integrated flexible hinge guide structure is easy to manufacture.

[0031] 2) This invention adjusts each piezoelectric stack to the same height by using a wedge-shaped adjusting block, and then compresses the disc spring assembly by a pre-tightening rod located in the center to provide each piezoelectric stack with a basically consistent pre-tightening force, thereby improving the output consistency of the parallel piezoelectric stacks and enabling the vibration output to have high precision.

[0032] 3) The top of the motion platform of the present invention is unobstructed, allowing for the installation of larger loads without reducing the vibration bandwidth;

[0033] 4) The lower external thread of the preload rod is provided with a slot and an inner conical surface. After installation and tightening, the locking screw with the outer conical surface is screwed into the inner thread of the lower preload rod. Through the wedge force amplification effect of the inner and outer conical surfaces and the radial force transmitted by the slot, the locking force of the lower thread of the preload rod is improved, and the anti-loosening is more reliable. Attached Figure Description

[0034] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0035] Figure 1 A three-dimensional diagram of a piezoelectrically driven high-bandwidth linear vibration table;

[0036] Figure 2 This is a top view of a piezoelectrically driven high-bandwidth linear vibration table.

[0037] Figure 3 for Figure 2 A sectional view along direction AA;

[0038] Figure 4 A partial three-dimensional view of a piezoelectrically driven high-bandwidth linear vibration table;

[0039] Figure 5 A three-dimensional view of the base of a piezoelectrically driven high-bandwidth linear vibration table;

[0040] Figure 6 for Figure 5 A magnified view of a section at point E in the middle;

[0041] Figure 7A three-dimensional cross-sectional view of an integrated flexible hinge guide rail for a piezoelectrically driven high-bandwidth linear vibration table.

[0042] Figure 8 This is a cross-sectional view of the preload rod of a piezoelectrically driven high-bandwidth linear vibration table.

[0043] Explanation of reference numerals in the attached figures:

[0044] 1-Base (features: 1-1-base plate; 1-2-bore; 1-3-threaded through hole; 1-4-piezoelectric stack support block; 1-5-first flexible hinge.) 2-Integrated flexible hinge guide rail (features: 2-1 motion platform; 2-2 flexible hinge unit; 2-3 fixed wall; 2-4 groove; 2-5 slot.) 3-piezoelectric stack; 4-wedge adjustment block; 5-disc spring assembly; 6-preload rod (features: 6-1-flange; 6-2-step; 6-3-external thread; 6-4-internal thread; 6-5-slot; 6-6-conical surface.) 7-locking screw. Detailed Implementation

[0045] The specific embodiments of the present invention will now be described with reference to the accompanying drawings.

[0046] like Figures 1 to 8 As shown, a piezoelectric-driven high-bandwidth linear vibration table includes: a base 1, an integrated flexible hinge guide rail 2, a piezoelectric stack 3, a wedge-shaped adjustment block 4, a disc spring assembly 5, a preload rod 6, and a locking screw 7.

[0047] like Figure 5 and Figure 6 As shown, the base 1 includes: a base plate 1-1, a boss 1-2, a threaded through hole 1-3, a piezoelectric stack support block 1-4, and a first flexible hinge 1-5. The boss 1-2 is located at the upper center of the base 1-1. The threaded through hole 1-3 is located at the center of the boss 1-2. The piezoelectric stack support block 1-4 is provided on the four sides of the boss 1-2 by means of slotting. The piezoelectric stack support block 1-4 is connected to the boss 1-2 through the first flexible hinge 1-5.

[0048] like Figure 7 As shown, the integrated flexible hinge guide rail 2 includes: a central square motion platform 2-1, flexible hinge units 2-2 symmetrically arranged on the four outer sides of the motion platform 2-1, and four outermost fixed walls 2-3. A circular groove 2-4 is provided in the center of the top of the motion platform 2-1. The center and lower side of the motion platform 2-1 are cavities. Through slots 2-5 are provided on the four sides of the integrated flexible hinge guide rail 2. Figure 3 As shown, the integrated flexible hinge guide rail 2 is mounted on the base 1 and is fixedly connected to the base plate 1-1 through the fixed wall 2-3.

[0049] like Figure 3 and 4 As shown, the piezoelectric stack 3 is placed on top of the piezoelectric stack support blocks 1-4 of the base 1.

[0050] like Figure 3 and Figure 4 As shown, the wedge-shaped adjustment block 4 includes a stationary wedge and a moving wedge. After the inclined surface of the stationary wedge engages with the inclined surface of the moving wedge, the entire block is placed in the gap between the boss 1-2 of the base 1 and the piezoelectric stack support block 1-4, and located at the slots 2-5 opened on the four sides of the integrated flexible hinge guide rail 2.

[0051] like Figure 1 and Figure 3 As shown, the disc spring assembly 5 is placed in the groove 2-4 of the integrated flexible hinge guide rail 2.

[0052] like Figure 3 and Figure 8 As shown, the preload rod 6 is connected from top to bottom to the threaded through hole 1-3 in the center of the base 1 via an external thread 6-3. The flange 6-1 at the upper end of the preload rod 6 is in pressing contact with the disc spring assembly 5.

[0053] like Figure 3 As shown, the locking screw 7 is screwed into the internal thread 6-4 at the lower end of the preload rod 6 from bottom to top via the thread.

[0054] like Figure 1 , Figure 3 and Figure 7 As shown, the flexible hinge unit 2-2 of the integrated flexible hinge guide rail 2 is a flexible hinge with a thick middle and thin ends, and the flexible hinge unit 2-2 on each side is distributed in two groups at the upper and lower ends.

[0055] like Figure 1 , Figure 3 and Figure 7 As shown, the motion platform 2-1 of the integrated flexible hinge guide rail 2 has a large top thickness and is designed to be lightweight, increasing the top bending stiffness while reducing the mass of the motion platform. The top surface of the motion platform 2-1 is higher than the flexible hinge units 2-2 on the four sides and the outer fixed wall 2-3, and mounting screw holes for fixing the load are opened on the four sides of the top surface.

[0056] like Figure 3 and Figure 8 As shown, the upper part of the pretension rod 6 has a hollow structure to reduce the mass of the cantilever.

[0057] like Figure 3 and Figure 8As shown, the lower external thread 6-3 of the preload rod 6 has an internal thread 6-4, and the lower end of the internal thread 6-4 has a conical surface 6-6, which mates with the conical surface of the locking screw 7. The lower threaded section of the preload rod 6 has a slot 6-5 extending from bottom to top. After the preload rod 6 is tightened onto the base 1 by the step 6-2 on its lower side, the locking screw 7 is screwed into the preload rod 6 from bottom to top. Due to the wedge-shaped force transmission effect of the conical surface and the elastic deformation of the slot, the thread engagement between the preload rod 6 and the base 1 is tighter, thus preventing loosening.

[0058] The support blocks 1-4, the first flexible hinges 1-5, the piezoelectric stack 3, and the wedge-shaped adjustment block 4 described in this embodiment are arranged as a group of components, forming a symmetrical circular array around the axis of the base 1, with a total of four arrays. It should be noted that the number of circular arrays here can be two, six (under the condition of eliminating interference), or others; the four arrays in this embodiment are preferred.

[0059] The assembly method in this embodiment is as follows:

[0060] 1) Place each of the piezoelectric stacks 3 and each of the wedge-shaped adjustment blocks 4 in the corresponding positions of the base 1;

[0061] 2) Adjust each of the wedge-shaped adjustment blocks 4 so that the upper end face of each of the piezoelectric stacks 3 is at the same height as the upper surface of the bottom plate 1-1 of the base 1;

[0062] 3) Install the integrated flexible hinge guide rail 2;

[0063] 4) The pre-tensioning rod 6 is used to press the disc spring assembly 5 with calibrated stiffness into the groove 2-4 of the integrated flexible hinge guide rail 2 with a preset compression amount (the preset compression amount is adjusted according to the amplitude and bandwidth requirements (a larger compression amount results in a smaller amplitude and higher bandwidth)).

[0064] 5) To obtain higher vibration accuracy and bandwidth, strain gauges can be attached to the side of each piezoelectric stack 3 to monitor the vertical strain changes of each piezoelectric stack 3 before and after the pre-tightening rod 6 is tightened. If the strain difference is large, the wedge-shaped adjustment block 4 can be adjusted a second time through the slots 2-5 on the side of the integrated flexible hinge guide rail 2 to make the pre-tightening force of each piezoelectric stack 3 more uniform;

[0065] 6) Screw the locking screw 7 into the lower end of the preload rod 6 to prevent loosening.

[0066] The parts of this invention not described in detail are well-known in the art. The embodiments described above are merely preferred embodiments of the present invention, and do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Various modifications and improvements to the technical solutions of this invention made by those skilled in the art without departing from the spirit of the invention should fall within the protection scope defined by the claims of this invention.

Claims

1. A piezoelectrically driven high-bandwidth linear vibration table, characterized in that, The vibration table includes: The base includes a base plate, a boss, a threaded through hole, a piezoelectric stack support block, and a first flexible hinge. The boss is located in the center of the base plate, the threaded through hole is located in the center of the boss, and several piezoelectric stack support blocks are located around the boss and are respectively connected to the boss through the first flexible hinge. An integrated flexible hinge guide rail includes a motion platform, flexible hinge units, fixed walls, grooves, and slots. The motion platform is square, with the flexible hinge units and four outermost fixed walls symmetrically arranged on its four outer sides. The groove is located at the top center of the motion platform, and the slots are provided on all four sides of the integrated flexible hinge guide rail. The piezoelectric stack has its lower end connected to the top of the piezoelectric stack support block and its upper end connected to the motion platform of the integrated flexible hinge guide rail. A wedge-shaped adjustment block is located in the gap between the boss and the piezoelectric stack support block; The disc spring assembly is located in the groove at the center of the top of the motion platform; The preload rod has its lower end connected to the base via a thread, and its upper end presses the disc spring assembly together via a flange. The locking screw has an external thread that matches the internal thread at the lower end of the preload rod.

2. A piezoelectrically driven high-bandwidth linear vibration table according to claim 1, characterized in that, The flexible hinge unit of the integrated flexible hinge guide rail is a flexible hinge with a thick middle and thin ends, and the flexible hinge units on each side are distributed in two arrays at the top and bottom ends.

3. A piezoelectrically driven high-bandwidth linear vibration table according to claim 1, characterized in that, The motion platform of the integrated flexible hinge guide rail has a large top thickness and is designed to be lightweight, so as to increase the bending stiffness of the top while reducing the mass. The top surface of the motion platform is higher than the flexible hinge units on the four sides and the outer fixed wall, and the top surface has mounting screw holes for fixing the load on the four sides.

4. A piezoelectrically driven high-bandwidth linear vibration table according to claim 1, characterized in that, The wedge-shaped adjustment block includes a stationary wedge and a moving wedge. After the inclined surface of the stationary wedge and the inclined surface of the moving wedge are engaged, the whole block is placed in the gap between the boss of the base and the piezoelectric stack support block.

5. A piezoelectrically driven high-bandwidth linear vibration table according to claim 1, characterized in that, The upper part of the preload rod has a hollow structure to reduce the cantilever mass; the lower part of the preload rod has an internal thread within its external thread, and the lower end of the internal thread has a conical surface; the conical surface mates with the conical surface of the locking screw; the lower threaded section of the preload rod has a slot from bottom to top; after the preload rod is tightened onto the base by the step on its lower side, the locking screw is screwed into the preload rod from bottom to top; due to the wedge force amplification effect of the conical surface and the elastic deformation of the slot, the thread engagement between the preload rod and the base is more tight.

6. A piezoelectrically driven high-bandwidth linear vibration table according to claim 1, characterized in that, The support block, the first flexible hinge, the piezoelectric stack, and the wedge-shaped adjustment block are arranged as a group of components in a symmetrical circular array around the axis of the base. The number of arrays is two, four, or, under the condition of eliminating interference, six.

7. A method for assembling a piezoelectrically driven high-bandwidth linear vibration table according to any one of claims 1 to 6, characterized in that, The specific steps are as follows: (1) First, place each of the piezoelectric stacks and each of the wedge-shaped adjustment blocks in the corresponding positions of the base; (2) Adjust each of the wedge-shaped adjustment blocks so that the upper end face of each of the piezoelectric stacks is at the same height relative to the upper surface of the base plate; (3) Install the integrated flexible hinge guide rail; (4) The pre-tensioning rod is used to press the disc spring assembly with calibrated stiffness into the groove of the integrated flexible hinge guide rail according to the preset compression amount; (5) Screw the locking screw into the lower end of the preload rod to prevent loosening.

8. A method for assembling a piezoelectrically driven high-bandwidth linear vibration table according to claim 7, characterized in that, To achieve higher vibration accuracy and bandwidth, strain gauges are attached to the sides of each piezoelectric stack to monitor the vertical strain changes of each piezoelectric stack before and after the pre-tightening rod is tightened. If the strain difference is large, the wedge-shaped adjustment block is adjusted a second time through the slot on the side of the integrated flexible hinge guide rail to make the pre-tightening force of each piezoelectric stack more uniform.

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