What Is a Floating Joint?
A floating joint is a joint that permits eccentricity and angular misalignment between members. Eccentricity and angular misalignment can be absorbed by sliding the internal spherical structure and the holder covering the sphere.
It is mainly used to connect cylinders, which are linear actuators, to guide rails and other linear moving parts.
Although the basic structure is the same as that of a ball joint, a floating joint cannot be used to transmit rotational or oscillating motion because it is not a joint for rotation or oscillation.
Uses of Floating Joints
Floating joints are mainly used to connect linear actuators, such as cylinders driven by compressed air or electric power, to linear moving parts such as guide rails.
However, unless both actuators are assembled with a high level of precision, a large resistance force may be generated due to eccentricity or angular misalignment, or the cylinder may be damaged.
In contrast, the use of floating joints allows eccentricity and misalignment to be tolerated, eliminating the need for parallelism and centering, and making it possible to construct a linear motion system easily.
Principle of Floating Joints
Floating joints consist of a sphere, a holder to hold the sphere, and screws and nuts to connect the parts. Due to physical constraints, the holder must cover more than half of the sphere’s surface to hold the sphere, so there is a limit to the allowable angular deflection.
Typical floating joints are set at an allowable eccentricity of about 5°, and if the eccentricity is greater than this, the resistance will increase or the joint will break. As described above, the eccentricity and angular misalignment allowances are only to simplify the work of aligning parallelism and centering during assembly, and cannot be used for transmission between members with widely different centering directions, such as ball joints and universal joints.
In addition, since failure occurs due to damage to the sphere or holder when a large impact force is applied, it is necessary to use a cylinder with an air cushion or rubber cushion or install an external shock-absorbing mechanism such as a shock absorber.