Piezoelectric actuator driving-based three-axis positioning micron-sized small part assembling platform

Abstract

A three-axis positioning micron-sized small part assembling platform based on piezoelectric actuator driving relates to the technical field of precision mechanical engineering and comprises a biaxial piezoelectric positioning platform. The loading platform is used for placing parts, and the first piezoelectric actuator is used for driving the loading platform to move in a micron order along the X axis or the second piezoelectric actuator is used for driving the loading platform to move in the micron order along the Y axis; and the rotary piezoelectric positioning platform is connected to the bottom of the biaxial piezoelectric positioning platform and is provided with a third piezoelectric brake for driving the biaxial piezoelectric positioning platform to perform micron-order rotation. The technical bottlenecks that a traditional positioning platform is large in size and low in precision are broken through, micron-level positioning of X / Y-axis translation precision and rotation angle errors is achieved, the size is smaller than that of similar products, the platform is more suitable for high-precision scenes such as microelectronic packaging and biochip assembling, and an innovative solution is provided for miniaturized precision manufacturing equipment.

Description

Technical Field

[0001] The present invention relates to the technical field of precision mechanical engineering, and in particular to a three-axis positioning micron-level small parts assembly platform driven by a piezoelectric actuator. Background Art

[0002] As microelectronics, optical devices and biomedical equipment develop towards miniaturization and high integration, micron-level precision assembly technology places higher demands on the accuracy, stability and compactness of multi-axis positioning platforms. Traditional assembly methods mostly use a robotic arm of about 50 to 100 cm in size to assemble millimeter-level parts, which is prone to the situation where the inertia force is too large, making it difficult to position the parts. In addition, the repetitive positioning accuracy of the robotic arm is usually at the level of tens of microns, which is difficult to meet the needs of high-precision assembly tasks. Therefore, a more precise assembly platform is usually used to fine-tune the position of the parts to cooperate with the work of the robotic arm.

[0003] However, existing small parts assembly positioning platforms usually contain multiple mechanical components, with a complex overall structure and large size, which makes it difficult to miniaturize and limits the application scenarios. Moreover, the driving core of such positioning platforms mostly relies on electromagnetic motors. Although this structure can achieve basic motion functions, it causes angular deviations such as pitch and yaw due to mechanical assembly errors and inter-axis coupling effects, and breakthroughs in micron-level positioning accuracy always face bottlenecks. How to design a positioning platform that is both high-precision and miniaturized has become a technical problem that urgently needs to be overcome in the field of micron-level parts assembly. Summary of the invention

[0004] The purpose of the present invention is to provide a three-axis positioning micron-level small parts assembly platform driven by a piezoelectric actuator to achieve miniaturization and improve positioning accuracy.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solution: a three-axis positioning micron-level small parts assembly platform driven by a piezoelectric actuator, comprising:

[0006] A biaxial piezoelectric positioning platform is provided with a carrier for placing parts and a first piezoelectric actuator for driving the carrier to move in micrometers along the X axis or a second piezoelectric actuator for moving in micrometers along the Y axis;

[0007] The rotating piezoelectric positioning platform is connected to the bottom of the biaxial piezoelectric positioning platform and is provided with a third piezoelectric brake for driving the biaxial piezoelectric positioning platform to rotate in micrometer level.

[0008] Preferably, the first piezoelectric actuator, the second piezoelectric actuator, and the third piezoelectric brake have the same structure, each including a base, a piezoelectric sheet disposed on the base, and a driving mechanism for inputting a driving signal to the piezoelectric sheet. A dial made of zirconia is fixedly provided at the outer end of the piezoelectric sheet, and a tip structure is formed on the outer side of the dial for contacting the driven member.

[0009] More preferably, a limiting block for pressing the piezoelectric sheet to limit the deformation amount of the piezoelectric sheet in the Z-axis direction is respectively provided on both sides of the base. The base is provided with a plurality of bumps that can adjust their positions along the length direction of the piezoelectric sheet, and a tip structure is formed on the outer side of the bumps and abuts against the inner end of the piezoelectric sheet.

[0010] More preferably, the biaxial piezoelectric positioning platform includes a first base and a Y-axis support frame slidably connected to the first base. An X-axis guide rod is installed on the inner wall of the Y-axis support frame, and the stage is slidably connected to the X-axis guide rod. A Y-axis slider is provided on each of the two side walls of the Y-axis support frame, and the Y-axis slider is slidably connected to the corresponding Y-axis slide rail. The second piezoelectric actuator is disposed on one side of one of the Y-axis sliders, and the dial at its outer end abuts against the Y-axis slider. When the second piezoelectric actuator deforms, friction can be formed between its dial and the Y-axis slider, thereby actuating the Y-axis slider to move the Y-axis support frame and the stage in the Y-axis direction.

[0011] More preferably, a Y-axis guide rod perpendicular to the X-axis guide rod is provided below the Y-axis support frame. The Y-axis guide rod penetrates into the stage and is slidably connected to the stage without interfering with the X-axis guide rod. An X-axis slider is fixed at one end of the Y-axis guide rod, and the X-axis slider is slidably connected to the corresponding X-axis slide rail. The dial at the outer end of the first piezoelectric brake abuts against the X-axis slider. When the first piezoelectric brake deforms, friction can be formed between its dial and the X-axis slider, thereby actuating the X-axis slider to move the Y-axis guide rod to drive the stage in the X-axis direction.

[0012] More preferably, a layer of zirconia sticker is provided on the contact surface of the X-axis slider that contacts the dial at the outer end of the first piezoelectric brake and on the contact surface of the Y-axis slider that contacts the dial at the outer end of the second piezoelectric actuator.

[0013] More preferably, the rotary piezoelectric positioning platform includes a second base and a driving shaft rotatably installed on the second base. A zirconia ring is fixedly installed on the outer periphery of the driving shaft. The dial at the outer end of the third piezoelectric actuator abuts against the outer side surface of the zirconia ring. When the third piezoelectric actuator deforms, friction can be formed between its dial and the zirconia ring, thereby actuating the zirconia ring to drive the driving shaft to rotate clockwise or counterclockwise.

[0014] More preferably, two bearings are also arranged at intervals on the outer side of the zirconia ring and abutted against its side surface, and the sliders at the outer ends of the third piezoelectric actuators and the two bearings are arranged at uniform intervals along the outer circumference of the zirconia ring to form triangular contact points.

[0015] More preferably, the top end of the drive shaft is connected with a rotating seat, the rotating seat is fixedly connected to the bottom of the biaxial piezoelectric positioning platform, and an optical scale disk is also coaxially and fixedly installed on the drive shaft between the rotating seat and the zirconia ring.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0017] 1. Through the direct drive of the first piezoelectric actuator, the second piezoelectric actuator and the third piezoelectric actuator, the transmission mechanisms (such as gears and lead screws) of traditional electromagnetic motors are abandoned, and the backlash and inertial errors are eliminated, so that the stage can achieve micron-level positioning accuracy in the X / Y-axis translation and rotation movements.

[0018] 2. The rotating piezoelectric positioning platform is directly connected to the bottom of the biaxial piezoelectric positioning platform, with a compact structure, much smaller than the traditional mechanical positioning platform, and is easy to be integrated into the internal part of the miniaturized device. Description of the Drawings

[0019] Figure 1 It is a schematic diagram of the overall structure in the embodiment;

[0020] Figure 2 It is a schematic diagram of a partial structure of the biaxial piezoelectric positioning platform in the embodiment;

[0021] Figure 3 It is a schematic diagram of a partial structure of the rotating piezoelectric positioning platform in the embodiment;

[0022] Figure 4 It is a schematic diagram of the structure of the first / second / third piezoelectric actuator in the embodiment;

[0023] Figure 5 It is a schematic diagram of the contact position between the piezoelectric actuator and the slider in the embodiment;

[0024] Figure 6 It is a schematic diagram of the movement track of the piezoelectric sheet in the excited state in the embodiment;

[0025] Figure 7 It is a simulation result diagram of the X-axis movement state with a duty ratio of 10% in the embodiment, where (a) displacement (b) velocity (c) acceleration;

[0026] Figure 8 It is a simulation result diagram of the Y-axis movement state with a duty ratio of 10% in the embodiment, where (a) displacement (b) velocity (c) acceleration;

[0027] Figure 9 Simulation result diagram of the Z - axis rotational motion state with a duty ratio of 5% in the embodiment, where (a) angle, (b) angular velocity, (c) angular acceleration;

[0028] Figure 10 Displacement simulation result diagram of the Y - axis drive at different duty ratios in the embodiment;

[0029] Figure 11 Velocity simulation result diagram of the Y - axis drive at different duty ratios in the embodiment;

[0030] Figure 12 Acceleration simulation result diagram of the Y - axis drive at different duty ratios in the embodiment;

[0031] Figure 13 Simulation result diagram of the Y - axis motion state when the friction coefficient changes in the embodiment.

[0032] In the figure:

[0033] 1 - First piezoelectric actuator 2 - Second piezoelectric actuator

[0034] 3 - Third piezoelectric brake 4 - Carrier stage 5a - Base

[0035] 5b - Piezoelectric sheet 5c - Pusher block 5d - Limit block

[0036] 5e - Bump 6a - First base 6b - Y - axis support frame

[0037] 6c - X - axis guide rod 6d - Y - axis slider 6e - Y - axis guide rod

[0038] 6f - X - axis slider 7 - Zirconia sticker 8a - Second base

[0039] 8b - Drive shaft 8c - Zirconia ring 8d - Bearing

[0040] 8e - Rotating seat 8f - Optical scale disk. Detailed implementation manners

[0041] For the convenience of those skilled in the art, the present invention will be further described below in conjunction with the embodiments and the accompanying drawings. The content mentioned in the implementation manners does not limit the present invention.

[0042] It should be noted in advance that in the present invention, unless otherwise clearly specified and defined, terms such as "installation", "connection", "linkage", "fixation" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. In addition, in the present invention, unless otherwise clearly specified and defined, the first feature being "on" or "under" the second feature may include the first and second features being in direct contact, or may include the first and second features not being in direct contact but being in contact through additional features therebetween.

[0043] As Figures 1 to 3 shown, a three-axis positioning micro-component assembly platform driven by a piezoelectric actuator includes:

[0044] A biaxial piezoelectric positioning platform, provided with a stage 4 for placing components and a first piezoelectric actuator 1 for driving the stage 4 to move in the micron level along the X-axis or a second piezoelectric actuator 2 for driving the stage 4 to move in the micron level along the Y-axis;

[0045] A rotary piezoelectric positioning platform, connected to the bottom of the biaxial piezoelectric positioning platform, provided with a third piezoelectric brake 3 for driving the biaxial piezoelectric positioning platform to rotate in the micron level.

[0046] In the above structure, the first piezoelectric actuator 1, the second piezoelectric actuator 2, and the third piezoelectric brake 3 have the same structure. As Figure 4 shown, they all include a base 5a, a piezoelectric sheet 5b disposed on the base 5a, and a driving mechanism for inputting a driving signal to the piezoelectric sheet 5b. A dial block 5c made of zirconia is fixedly provided at the outer end of the piezoelectric sheet 5b, and a tip structure is formed on the outer side of the dial block 5c for contacting the driven member. By uniformly designing the modular structures of the first piezoelectric actuator 1, the second piezoelectric actuator 2, and the third piezoelectric actuator 3 and adopting the tip contact mechanism of the zirconia dial block 5c, the driving efficiency and system reliability are significantly improved. The high hardness and low wear characteristics of the zirconia material enable the tip of the dial block 5c to form a local high-pressure region when contacting the driven member, which can effectively reduce the relative slip amount of the friction pair. At the same time, the contact area of the tip structure is smaller, which can avoid the stress dispersion problem of the traditional planar friction pair and improve the driving force transmission efficiency.

[0047] Wherein, a limiting block 5d for pressing the piezoelectric sheet 5b to limit the deformation amount of the piezoelectric sheet 5b in the Z-axis direction is respectively arranged on both sides of the base 5a. The base 5a is provided with two bumps 5e that can adjust their positions along the length direction of the piezoelectric sheet 5b. The outer sides of the bumps 5e form a tip structure and abut against the inner ends of the piezoelectric sheet 5b. Designing the two bumps 5e applying pre-pressure can keep the deformation direction of the piezoelectric sheet stable, and the bumps 5e reduce the influence on the deformation of the piezoelectric sheet with a smaller contact area. The overall structural size of this piezoelectric actuator can be controlled within a length of 30 mm and a width of 14.5 mm. The tiny volume can save more overall occupied space of the assembly platform.

[0048] For the biaxial piezoelectric positioning platform, it includes a first base 6a and a Y-axis support frame 6b slidably connected to the first base 6a. An X-axis guide rod 6c is installed on the inner wall of the Y-axis support frame 6b. The stage 4 is slidably connected to the X-axis guide rod 6c. A Y-axis slider 6d is arranged on both side walls of the Y-axis support frame 6b, and the Y-axis slider 6d is slidably connected to the corresponding Y-axis slide rail. The second piezoelectric actuator 2 is arranged on one side of one of the Y-axis sliders 6d, and the dial block 5c at its outer end abuts against the Y-axis slider 6d. When the second piezoelectric actuator 2 deforms, friction can be formed between its dial block 5c and the Y-axis slider 6d, thereby actuating the Y-axis slider 6d to move the Y-axis support frame 6b and the stage 4 along the Y-axis direction. The Y-axis support frame 6b and the X-axis guide rod 6c adopt a nested structure. The Y-axis slider 6d moves with the slide rail bearing frame, and the X-axis guide rod 6c directly drives the stage 4. The two-axis movement planes are perpendicular to each other and there is no layer-by-layer stacking, greatly reducing the volume. The second piezoelectric actuator 2 is driven by the contact friction between the zirconia dial block 5c and the Y-axis slider 6d. Using the micron-level deformation of the piezoelectric sheet 5b is directly converted into the displacement of the slide rail, there is no reverse clearance caused by gear or lead screw transmission, and higher Y-axis positioning accuracy can be achieved.

[0049] Furthermore, a Y-axis guide rod 6e perpendicular to the X-axis guide rod 6c is arranged below the Y-axis support frame 6b. The Y-axis guide rod 6e penetrates into the stage 4 and is slidably connected to the stage 4 without interfering with the X-axis guide rod 6c. One end of the Y-axis guide rod 6e is fixed with an X-axis slider 6f, and the X-axis slider 6f is slidably connected to the corresponding X-axis slide rail. The dial block 5c at the outer end of the first piezoelectric brake 1 abuts against the X-axis slider 6f. When the first piezoelectric brake 1 deforms, friction can be formed between its dial block 5c and the X-axis slider 6f, thereby actuating the X-axis slider 6f to move the stage 4 along the X-axis direction driven by the Y-axis guide rod 6e.

[0050] As Figure 5As shown in the figure, a layer of zirconia sticker 7 is provided on the contact surface of the X-axis slider 6f for contacting the outer end slider 5c of the first piezoelectric actuator 1 and on the contact surface of the Y-axis slider 6d for contacting the outer end slider 5c of the second piezoelectric actuator 2. The advantage of this is that: with the driving force generated by the friction between zirconia and zirconia, the slider is thus pushed to drive the overall platform. Since the hardness of zirconia is second only to that of diamond and has a relatively high hardness, and the driving end and the driven end are made of the same material, the wear problem during long-term use can be reduced. Moreover, due to its high hardness, it can be regarded as a rigid body, which does not affect the thrust generated during the deformation of the piezoelectric material.

[0051] The rotary piezoelectric positioning platform in this embodiment includes a second base 8a and a drive shaft 8b rotatably mounted on the second base 8a. A zirconia ring 8c is fixedly mounted on the outer periphery of the drive shaft 8b. The slider 5c at the outer end of the third piezoelectric actuator 3 abuts against the outer side surface of the zirconia ring 8c. When the third piezoelectric actuator 3 deforms, friction can be formed between its slider 5c and the zirconia ring 8c, thereby actuating the zirconia ring 4c to drive the drive shaft 8b to rotate clockwise or counterclockwise. The micron-level deformation of the third piezoelectric actuator 3 is directly converted into the rotational displacement of the drive shaft 8b through the rigid contact friction between the zirconia slider 5c and the zirconia ring 8c, without the backlash error of gear or worm drive, and the precision is higher. Additionally, it should be noted that those skilled in the art should know that by frequently applying an electrical signal to the third piezoelectric actuator 3, it can be deformed rapidly and repeatedly, and then the slider 5c can friction the zirconia ring 8c multiple times within an extremely short time, thereby driving the zirconia ring 8c to rotate.

[0052] In order to enable the third piezoelectric actuator 3 to effectively output force during driving, two bearings 8d abutting against its side surface are also spaced apart on the outer side of the zirconia ring 8c. The slider 5c at the outer end of the third piezoelectric actuator 3 and the two bearings 8d are evenly spaced along the outer periphery of the zirconia ring 8c in a circular pattern to form a triangular contact point position. This can prevent the driving cylinder from generating eccentric motion due to the thrust generated when the piezoelectric sheet deforms. Therefore, in this way, the rotation center position can be maintained unchanged, enabling the third piezoelectric actuator 3 to effectively output.

[0053] In addition, the top end of the drive shaft 8b is connected to a rotating seat 8e. The rotating seat 8e is fixedly connected to the bottom of the biaxial piezoelectric positioning platform. An optical scale disk 8f is also coaxially and fixedly mounted on the drive shaft 8b between the rotating seat 8b and the zirconia ring 8c. The optical scale disk 8f can be used to real-time monitor and feedback the rotational angle position of the drive shaft 8b in this embodiment.

[0054] When the three-axis positioning micro-component assembly platform driven by a piezoelectric actuator provided in the above-described embodiment is applied, the parent component can be placed on the stage 4, and the component can be grasped by an external manipulator device and then assembled into the corresponding slot or other structures of the parent component. During the assembly process, the position of the stage 4 can be finely adjusted at the micron level by the assembly platform of the present invention (the position to be adjusted can be determined with the assistance of an external vision device). It is mainly based on the core principle of direct drive by a piezoelectric actuator and efficient transmission of a homogeneous friction pair, and realizes three-axis precise positioning through a modular split architecture: the dual-axis piezoelectric positioning platform adopts a nested orthogonal slide rail layout, uses the inverse piezoelectric effect of the piezoelectric sheet to generate periodic deformation, drives the tip of the zirconia slider to contact the slide rail friction pair, and achieves micron-level step displacement; the rotary piezoelectric positioning platform realizes nano-level angle control through the radial friction drive of the piezoelectric slider and the zirconia ring. The three-axis motion unit is designed with a rigid connection to improve the compactness of the structure.

[0055] Simulation test

[0056] First, measure the friction coefficient of zirconia. Since the present invention selects zirconia material as the driving end, its hardness can reduce the wear generated during long-term use, and zirconia strips are pasted on the side wall of the slider in the driven part that contacts the driving end. Using the same material also reduces the problem of reduced working efficiency caused by wear. Therefore, measure the friction coefficient of the used material. Paste the zirconia strips on a moving platform and a stainless steel plate respectively, and place a load cell on another moving platform. Through the moving platform, the load cell is used to push the stainless steel plate to slide on the contact surface of the zirconia. Record the change in the voltage signal output by the load cell from contact to the start of sliding through the system control software LabVIEW, and record the numerical value of the voltage signal. Finally, calculate the measured force magnitude through the voltage-force conversion formula of the load cell.

[0057] Before the load cell and the stainless steel plate come into contact, the output voltage signal remains horizontal, indicating that the load cell is not affected by other external forces. After the start of contact, the voltage continuously rises to a peak and then drops to a stable voltage. This phenomenon means that the stainless steel plate starts to slide after breaking through the maximum static friction force. Therefore, the friction force received is the dynamic friction force. So the voltage signal maintains a certain value. This peak represents the occurrence of the maximum static friction force, and the stable voltage represents the magnitude of the dynamic friction force. The maximum static friction force as shown in Equation (1) and the dynamic friction force as shown in Equation (2) can be calculated through the voltage-force conversion formula of the load cell:

[0058]

[0059] The mass of the stainless-steel plate and the loaded counterweight is 2.1968 kg. According to the formula for Coulomb friction, the static friction coefficient (μs) and the dynamic friction coefficient (μk) are as shown in Equations (3) and (4):

[0060] μ s = f static / mg = 2.544675 / (2.1968×9.8) = 0.1182 (3);

[0061] μ k = f dynamic / mg = 233835 / (2.1968×9.8) = 0.1086 (4).

[0062] Then, dynamic simulation analysis is carried out using MATLAB. Substitute the parameters measured through experiments into the motion equation, and after actual calculation, the motion behaviors in the X-axis, Y-axis, and Z-axis rotation (a total of three-axis drives) are obtained. And when different duty ratios of the PWM (Pulse Width Modulation) signal are input, observe the change in the step amount of this positioning platform.

[0063] Based on the existing motion equation of the piezoelectric actuator, the schematic diagram of the motion trajectory of the piezoelectric actuator in the excited state is as Figure 6 shown, which can be divided into the contact stage and the separation stage. At the turning points of the two stages are the separation point and the collision point respectively. Input the parameters of the piezoelectric sheet used in this test. Through this model, the displacement and velocity generated under the drive signal can be calculated, and the force output in the Y direction within one cycle for its collision situation is expressed as Equation (5). Using the change in the velocity of the slider in the Y direction before and after the collision, the average forward force generated by the piezoelectric actuator is calculated to be 5.76 N, and it is substituted into the motion equation for calculation.

[0064]

[0065] First, simulate the motion state in the X-axis when the duty ratio is 10%. The result is as Figure 7 shown, at Figure 7(b) It can be seen that the speed continues to increase at the beginning. This stage indicates that the piezoelectric sheet is in an excited state. Therefore, it continuously pushes to increase the speed of the stage. Then, the excitation of the piezoelectric sheet is stopped. At this time, the driving force provided by the piezoelectric sheet is zero, but there is still an inertial force that causes the stage to continue to displace, and the speed continuously decreases to zero due to the action of friction. After the speed drops to zero, the stage stops moving, so the position remains unchanged. From the simulation result diagram of acceleration as shown in 7(c), it can be seen that during the stage of exciting the piezoelectric sheet, the acceleration continuously decreases. The reason is that as the moving speed increases, the sliding friction force generated by the lubricating oil film becomes larger, so the acceleration continuously decreases. After the piezoelectric sheet stops being excited, the speed continuously decreases, causing the sliding friction force caused by the oil film to continuously decrease, and thus the acceleration increases.

[0066] From the above results, it is obtained that under the condition of a Duty ratio of 10%, the stepping amount of the X-axis drive is approximately 1.44 μm. Then, the simulation results of the Y-axis movement are as follows Figure 8 shown. Similarly, driven by a PWM signal with a Duty ratio of 10%, it can be seen that the trend is the same as that in the X-axis drive. The stepping amount during the Y-axis drive is 1.13 μm. Although the same piezoelectric actuator is used as the driving device, the moving parts and mechanism designs involved in the drive are different, so the generated friction forces are different, resulting in different results.

[0067] Next, the simulation of the Z-axis rotation is carried out. The Z-axis rotation is driven by a PWM signal with a Duty ratio of 5%. Figure 9 is the simulation result of the Z-axis rotational movement. From Figure 9 (b), it can be seen that after the piezoelectric actuator stops driving, the deceleration stage time is longer than that of the X-axis and Y-axis movements. Since there is only rolling friction acting on the Z-axis rotation, the friction force is smaller, so there will be a longer deceleration time. And in Figure 9 (c), the acceleration does not change during the driving process and after stopping driving. It is also because there is no lubricating friction force in the Z-axis rotation, so the friction force size does not change due to the change in speed, so the acceleration remains constant.

[0068] Through the above simulations, the motion states of the three-axis positioning platform designed in this study during the movement of each axis are obtained. Next, the relationship between the displacement changes under different Duty ratios is explored. The simulation during the Y-axis drive is used for comparison. Figure 10Displacement diagrams with duty ratios of 3 - 5% respectively. It can be seen from the figures that the displacement generated by the positioning platform under a single PWM signal, that is, the step amount of the positioning platform is 0.10μm, 0.20μm, and 0.31μm. When the excitation time of the piezoelectric element increases, the step amount also increases, but the step amount and the excitation time of the piezoelectric element do not show a linear relationship. The reason is Figure 11 and Figure 12 From the simulation results, Figure 10 and Figure 11 are respectively the simulation results of speed and acceleration with a duty ratio of 3 - 5% under a single PWM signal. When the duty ratio increases, the acceleration time during the movement of the piezoelectric actuator increases, and the maximum speed also increases accordingly. Therefore, the displacement results do not show a linear relationship.

[0069] This test further explores the influence on the movement state of the positioning platform when different materials are used as friction elements. Different friction elements mean a change in the friction coefficient, resulting in a change in the driving force provided by the piezoelectric actuator. Therefore, the step amount, maximum speed, and acceleration in the movement state will all change. From the formula of Coulomb friction, it can be deduced that when the friction coefficient increases, the resulting driving force also increases. Since the piezoelectric actuator in this study uses friction as the driving force, the friction element selected for this test is zirconia. The movement states with friction coefficients of 0.2, 0.4, and 0.6 of the friction element are simulated, and the driving is set under the condition of a duty ratio of 10%. Figure 13 is the simulation result during Y - axis driving. It can be seen that when the friction coefficient increases, due to the increase in the driving force, the step amount and speed of the stage also increase accordingly, indicating that the stage can move while carrying heavier parts. However, in the use of the positioning platform, high positioning accuracy is one of the necessary conditions. Therefore, appropriate materials need to be selected according to different usage conditions to achieve the best positioning effect.

[0070] Result Analysis

[0071] 1. Verification of the friction characteristics of zirconia. The maximum static friction force (corresponding value of the peak voltage) and dynamic friction force (corresponding value of the stable voltage) between the zirconia and the stainless - steel contact surface are measured through a load cell, and the static friction coefficient (μs) and dynamic friction coefficient (μk) are calculated based on Coulomb's formula. The friction coefficient between the zirconia sticker and the stainless - steel plate shows that zirconia can effectively reduce wear as a friction pair material, verifying the feasibility of using it as the driving - end material.

[0072] As the driving - end material, its low friction coefficient (μs / μk) reduces wear during long - term use, extends the equipment life, and at the same time avoids the problem of efficiency decline caused by material mismatch. Both the driving end and the side wall of the slider use zirconia, and the wear is further reduced through contact of the same material to ensure the movement stability.

[0073] 2. Triaxial motion behavior simulation. X / Y axis drive: Under the drive of a PWM signal with a duty cycle of 10%, the step size in the X axis is 1.44 μm, and in the Y axis is 1.13 μm. The trend of acceleration change shows that the sliding friction caused by the lubricating oil film increases with the increase in speed, resulting in a decrease in acceleration; after stopping the drive, the balance between inertial force and friction determines the deceleration process. Z axis rotation: When the duty cycle is 5%, the rolling friction is small, the deceleration time is long, and the acceleration remains constant (without the influence of lubricating friction).

[0074] The linear stepping (μm level) in the X / Y axes and the rotational control in the Z axis achieve high-precision positioning in three-dimensional space, meeting the requirements of precision equipment for multi-degree-of-freedom motion. By adjusting the PWM duty cycle, the step size can be precisely controlled (such as 0.10 - 0.31 μm in the Y axis) to adapt to the positioning accuracy requirements of different scenarios.

[0075] 3. Relationship between duty cycle and step size. When the duty cycle increases (3% - 5%), the step size in the Y axis increases non-linearly (0.10 μm → 0.31 μm). The reason is that the maximum speed increases due to the extended excitation time, but it is affected by the non-linearity of friction.

[0076] 4. Influence of friction coefficient on driving force. When the friction coefficient (0.2 → 0.6) increases, the driving force increases, and the step size and speed in the Y axis also increase accordingly, but a trade-off needs to be made between high load-bearing capacity and positioning accuracy. It can be seen that by replacing the friction element (such as zirconia with μ = 0.2 - 0.6), the driving force and load-bearing capacity can be adjusted to adapt to different load conditions.

[0077] The present invention breaks through the technical bottlenecks of traditional positioning platforms, such as large volume and low precision, realizes micron-level positioning of the translation accuracy of the X / Y axes and the rotation angle error, has a smaller volume than similar products, and the life of the zirconia homogeneous friction pair exceeds 10,000 hours without maintenance. Through direct piezoelectric drive control, it has both a millisecond-level response speed and multi-axis collaborative stability, and is suitable for high-precision scenarios such as microelectronic packaging and biochip assembly, providing an innovative solution for miniaturized precision manufacturing equipment.

[0078] To make it easier for those of ordinary skill in the art to understand the improvements of the present invention over the prior art, some drawings and descriptions of the present invention have been simplified, and the above embodiments are the preferred implementation schemes of the present invention. In addition, the present invention can also be implemented in other ways. Any obvious replacement without departing from the concept of the technical solution is within the protection scope of the present invention.

Claims

1. A three-axis positioning micro-component assembly platform driven by a piezoelectric actuator, characterized in that Comprising: A biaxial piezoelectric positioning platform, provided with a stage (4) for placing parts and a first piezoelectric actuator (1) for driving the stage (4) to move micron-level along the X-axis or a second piezoelectric actuator (2) for driving the stage (4) to move micron-level along the Y-axis; A rotary piezoelectric positioning platform, connected to the bottom of the biaxial piezoelectric positioning platform, provided with a third piezoelectric brake (3) for driving the biaxial piezoelectric positioning platform to rotate micron-level.

2. The three-axis positioning micro-component assembly platform driven by a piezoelectric actuator according to claim 1, wherein: The first piezoelectric actuator (1), the second piezoelectric actuator (2) and the third piezoelectric brake (3) have the same structure, all including a base (5a), a piezoelectric sheet (5b) arranged on the base (5a), and a driving mechanism for inputting a driving signal to the piezoelectric sheet (5b). A dial block (5c) made of zirconia is fixedly arranged at the outer end of the piezoelectric sheet (5b), and a tip structure is formed on the outer side of the dial block (5c) for contacting the driven part.

3. The three-axis positioning micro-component assembly platform driven by a piezoelectric actuator according to claim 2, characterized in that: On both sides of the base (5a), a limit block (5d) is respectively arranged for pressing the piezoelectric sheet (5b) to limit the deformation amount of the piezoelectric sheet (5b) in the Z-axis direction. The base (5a) is provided with a plurality of bumps (5e) whose positions can be adjusted along the length direction of the piezoelectric sheet (5b). The outer side of the bump (5e) forms a tip structure and abuts against the inner end of the piezoelectric sheet (5b).

4. The three-axis positioning micro-component assembly platform driven by a piezoelectric actuator according to claim 3, characterized in that: The biaxial piezoelectric positioning platform includes a first base (6a) and a Y-axis support frame (6b) slidably connected to the first base (6a). An X-axis guide rod (6c) is installed on the inner wall of the Y-axis support frame (6b). The stage (4) is slidably connected to the X-axis guide rod (6c). On both side walls of the Y-axis support frame (6b), a Y-axis slider (6d) is arranged, and the Y-axis slider (6d) is slidably connected to the corresponding Y-axis slide rail. The second piezoelectric actuator (2) is arranged on one side of one of the Y-axis sliders (6d), and the dial block (5c) at its outer end abuts against the Y-axis slider (6d). When the second piezoelectric actuator (2) deforms, friction can be formed between its dial block (5c) and the Y-axis slider (6d), thereby actuating the Y-axis slider (6d) to make the Y-axis support frame (6b) and the stage (4) move along the Y-axis direction.

5. The three-axis positioning micrometer-level small part assembly platform driven by a piezoelectric actuator according to claim 4, wherein: Below the Y-axis support frame (6b), a Y-axis guide rod (6e) perpendicular to the X-axis guide rod (6c) is arranged. The Y-axis guide rod (6e) penetrates into the stage (4) and is slidably connected to the stage (4) without interfering with the X-axis guide rod (6c). One end of the Y-axis guide rod (6e) is fixed with an X-axis slider (6f), and the X-axis slider (6f) is slidably connected to the corresponding X-axis slide rail. The dial block (5c) at the outer end of the first piezoelectric brake (1) abuts against the X-axis slider (6f). When the first piezoelectric brake (1) deforms, friction can be formed between its dial block (5c) and the X-axis slider (6f), thereby actuating the X-axis slider (6f) to make the Y-axis guide rod (6e) drive the stage (4) to move along the X-axis direction.

6. The three-axis positioning micro-component assembly platform driven by a piezoelectric actuator according to claim 5, characterized in that: The contact surface of the X-axis slider (6f) for contacting the outer end dial block (5c) of the first piezoelectric actuator (1) and the contact surface of the Y-axis slider (6d) for contacting the outer end dial block (5c) of the second piezoelectric actuator (2) are both provided with a layer of zirconia sticker (7).

7. The three-axis positioning micro-component assembly platform driven by a piezoelectric actuator according to claim 3, wherein: The rotary piezoelectric positioning platform includes a second base (8a) and a drive shaft (8b) rotatably mounted on the second base (8a). An outer peripheral of the drive shaft (8b) is fixedly provided with a zirconia ring (8c). The dial block (5c) at the outer end of the third piezoelectric actuator (3) abuts against the outer side surface of the zirconia ring (8c). When the third piezoelectric actuator (3) deforms, friction can be formed between its dial block (5c) and the zirconia ring (8c), thereby actuating the zirconia ring (4c) to drive the drive shaft (8b) to rotate clockwise or counterclockwise.

8. The three-axis positioning micro-component assembly platform driven by a piezoelectric actuator according to claim 7, characterized in that: Two bearings (8d) abutting against its side surface are further spaced apart on the outer side of the zirconia ring (8c). The dial block (5c) at the outer end of the third piezoelectric actuator (3) and the two bearings (8d) are arranged at equal intervals along the circumference of the zirconia ring (8c) to form a triangular contact point position.

9. The three-axis positioning micro-component assembly platform driven by a piezoelectric actuator according to claim 8, wherein: The top end of the drive shaft (8b) is connected to a rotating seat (8e). The rotating seat (8e) is fixedly connected to the bottom of the biaxial piezoelectric positioning platform. An optical scale disk (8f) is also coaxially and fixedly mounted on the drive shaft (8b) between the rotating seat (8b) and the zirconia ring (8c).

10. Application of the assembly platform according to any one of claims 1-9 in the assembly work of micron-scale small parts.

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