How do you calculate ball screw torque?

Ball screw is a mechanical transmission device used to convert rotary motion into linear motion. It is commonly used in various CNC machine tools, mechanical equipment and automation systems. Calculating the torque of a ball screw requires considering the following factors:

1. Input torque: Input torque is the external torque acting on the ball screw. It can be provided by the driving force, which can be a motor or other power device. The input torque is transmitted to the output through the ball system of the ball screw.

2. Ball screw transmission efficiency: The transmission efficiency of the ball screw is usually above 90%, which may vary depending on the specific ball screw type and usage conditions. The higher the transmission efficiency, the smaller the difference between output torque and input torque.

3. Ball screw dynamic parameters: The dynamic parameters of the ball screw include pitch, lead and ball diameter. Pitch refers to the distance the ball screw moves axially during one revolution of the nut. Lead refers to the angle of rotation required for a ball screw to move axially for one revolution. Ball diameter refers to the diameter of the balls used in the ball screw.

Generally speaking, the following formula can be used to calculate the torque of a ball screw:

Torque = (input torque × transmission efficiency) / (pitch × 2π)

Among them, the input torque and transmission efficiency are known parameters, the pitch represents the axial movement distance of the ball screw, and 2π represents the rotation angle of one revolution.

Please note that the units in the above formula must be consistent, for example, the unit of torque is Newton·meter (N·m) and the unit of pitch is meter (m).

It should be noted that the torque calculation of the ball screw is a simplified model. In actual applications, some other factors may need to be considered, such as the loading conditions of the ball screw, friction and wear, etc., which may affect the torque. When designing and selecting a ball screw, it is recommended to refer to the relevant ball screw design manual or consult a professional engineer for more accurate calculation methods and parameter selection.