Analyzing Flexible Hinges for Supporting, Jointing, Adjusting, and Measuring_Hinge Knowledge_Tallsen

The use of flexible hinge bearings is becoming increasingly prevalent in modern machines. These bearings simplify the assembly process and reduce the dimensional tolerance requirements for processing. Compared to fixed shape bearings, the flexible hinge bearing can effectively reduce the half-speed whirl of the liquid sliding friction bearing, thus preventing flutter.

Flexible hinge joints, composed of flexible hinges, are capable of transmitting thrust perpendicular to the direction of movement, while having low rigidity in horizontal and vertical directions. This makes them ideal for designing elastic universal joints with two rotational degrees of freedom. These joints have a compact structure and precise transmission capabilities.

The flexible hinge also enables self-adjustment of the surface of V-shaped grooves, avoiding relative movement between balls and the grooves when force changes. This adjustment mechanism, when applied to a device composed of three balls and three V-shaped grooves, reduces hysteresis between force and displacement by 95%.

Another application of the flexible hinge is its use in optical component bases. By adding adjustment screws on either side of the platform, the horizontal surface can be precisely deflected. This cost-effective solution offers high resolution in a small range of motion and can be utilized in lens assembly and other similar tasks.

In the context of increasing storage density and reading speed of optical discs, the rotational speed of the disc must also be increased accordingly, requiring the DVD/CD pickup head to have greater acceleration and better linearity. The flexible hinge mechanism is effective in solving these problems. For example, the University of Texas developed a lithography alignment table that utilizes a flexible hinge four-bar linkage as an adjustment mechanism. This mechanism allows for precise deflection of the platform on which the template is installed relative to the photosensitive substrate, enabling desired printing results.

In the field of measurement and calibration, linear displacement measurement sensors with sub-nanometer sensitivity have emerged over the past decade. Optical interferometers have been widely used in such sensors, but there is still a gap between the actual interference fringes and the ideal form used for fringe subdivision. X-ray interferometry can be used to accurately measure displacements at the sub-fringe level. Combined optical and X-ray interferometers, such as the COX1 at the National Physical Laboratory, offer large stroke capabilities and high resolution. The use of a flexible hinge parallel four-bar mechanism in these instruments enables the precise transmission of reverse displacement, allowing for calibration of linear displacement sensors with sub-nanometer sensitivity.

Various organizations and research institutions have also developed innovative solutions using flexible hinge mechanisms to achieve specific objectives. The National Bureau of Standards designed an integrated flexible hinge mechanism to connect X-ray and optical interferometers, reducing the impact on the driving element and improving adjustment accuracy. Germany developed a flexible hinge transmission mechanism with a symmetrical structure to increase the measurement range of an X-ray interferometer.

Flexible hinges have also found application in mechanical measuring instruments. Lever balances, such as the equal-arm knife-edge card lever balance, offer high resolution, and the use of flexible hinge suspension equibar bars further enhances resolution.

In conclusion, flexible hinge bearings and joints have become increasingly common in modern machines, offering simplified assembly processes and reduced dimensional tolerance requirements. These mechanisms exhibit low rigidity in specific directions while transmitting thrust or enabling precise deflection. Flexible hinges also find application in measurement and calibration instruments, providing sub-nanometer sensitivity. Various organizations and research institutions continue to develop innovative solutions using flexible hinge mechanisms to achieve specific objectives across a range of industries and applications.