helicalaxis

The helical axis is a concept in kinematics and mechanics that describes the axis around which a rigid body rotates while translating along its length. It is particularly useful in the analysis of screw motions, which combine rotation and translation. The helical axis is defined as the line that remains fixed in space during the motion of the body, and it passes through the instantaneous center of rotation (ICR) at any given moment.

In a screw motion, the helical axis is the line along which the body would move if it were to rotate without translation, and it is perpendicular to the direction of translation. The pitch of the screw, which is the distance the body moves along the helical axis per complete rotation, is a key parameter in describing the screw motion. The helical axis is also known as the screw axis or the axis of screw motion.

The helical axis can be determined using the velocity vectors of points on the body. Specifically, the helical axis is the line that is perpendicular to the velocity vectors of all points on the body. This property makes it a useful tool in the analysis of mechanisms and machines that involve screw motions, such as screws, bolts, and certain types of gears.

In summary, the helical axis is a fundamental concept in kinematics that describes the axis around which a rigid body rotates while translating along its length. It is defined as the line that remains fixed in space during the motion of the body and is perpendicular to the direction of translation. The helical axis is a key parameter in the analysis of screw motions and is useful in the design and analysis of mechanisms and machines that involve such motions.