Combining Flexible Hinges with Piezoelectric Actuation_Hinge Knowledge_Tallsen

Piezoelectric actuators are known for their smooth motion, high resolution, high stiffness, and high energy conversion efficiency. They are ideal for precise positioning in engineering applications. However, these actuators typically have only a few to tens of microns of displacement, which may not be sufficient for many applications that require a larger range of motion.

To overcome this limitation, flexible hinges can be used in conjunction with piezoelectric actuators. Flexible hinges provide smooth motion, do not require lubrication, have no backlash or friction, and offer high precision. They are the most suitable method for achieving actuator displacement. Furthermore, the flexible hinge mechanism provides appropriate preload for the piezoelectric actuator, preventing it from being subjected to tensile stress.

There are several typical examples of using piezoelectric element drive and flexible hinge mechanism transmission:

1. Ultra-precision positioning table: The US National Bureau of Standards developed a micro-positioning workbench in 1978 for line width measurement of photomasks. The workbench is driven by piezoelectric elements, and the flexible hinge mechanism is used for displacement amplification. It is compact, works in a vacuum, and can linearly position objects within a working range of 50mm with a resolution of 1nm or better.

2. Scanning tunneling microscope (STM): To expand the measurement range of STM, researchers have developed 2-dimensional ultra-precision worktables driven by a piezoelectrically driven flexible hinge mechanism. These worktables allow for large field measurements. For example, the US National Bureau of Standards reported a 500pm x 500pm STM probe with a 500mm field of view. The X-y workbench is driven by piezoelectric blocks, and the flexible hinge mechanism has a displacement amplification ratio of about 18.

3. Ultra-precision machining: Micro-positioning tool holders composed of piezoelectric elements, flexible hinge mechanisms, and capacitive sensors are used for ultra-precision diamond cutting. The tool holder has a stroke of 5um and a positioning resolution of about 1nm. It is used for precision connection processes like laser welding.

4. Print head: The print head of an impact dot matrix printer utilizes the principle of piezoelectric drive and flexible hinge mechanism transmission. The flexible hinge mechanism amplifies the displacement of the piezoelectric block and drives the movement of the printing needle. Multiple printing needles form the printing head, allowing for the printing of characters composed of dot matrices.

5. Optical auto focus: In automated production, high-precision autofocus systems are required to obtain high-quality images. Traditional motor drives have limited positioning accuracy and are limited by the magnification of the objective lens. Piezoelectric drive with a flexible hinge mechanism offers better repeatability and can focus on objective lenses with high magnification.

6. Piezoelectric motor: Piezoelectric motors can be designed using piezoelectric drive and flexible hinge mechanism transmission. These motors can achieve clamping and stepping rotation or linear motion between the mover and the stator. They can provide high positioning accuracy at low speeds and can withstand certain moments or forces.

7. Active radial air bearings: Active radial air bearings utilize flexible hinge mechanisms and piezoelectric drives to precisely control the radial displacement of a shaft. This improves the motion accuracy of the shaft compared to traditional air bearings.

8. Micro gripper: Micro grippers are used in micro-instrument assembly, biological cell manipulation, and fine surgery. They amplify the displacement of piezoelectric actuators through flexible hinge lever mechanisms to allow for the grasping of tiny objects.

The use of flexible hinges in supporting structures, connection structures, adjustment mechanisms, and measuring instruments is widely applicable in the fields of precision mechanical precision measurement, micron technology, and nanotechnology.

In conclusion, flexible hinges offer numerous advantages in achieving ultra-precise displacement and positioning with piezoelectric actuators. They provide smooth motion, high precision, and no friction or backlash. By using flexible hinge mechanisms to transfer and amplify the displacement of piezoelectric actuators, engineers can achieve larger movements and higher accuracy in a wide range of applications.