The linear ball screw servo motor actuator, or servo actuator, converts the rotation of the motor into a linear movement via a ball nut with ball screw assembly. The ball nut is attached to the rotor of the servo motor and rotates with it. The ball screw passes through the rotor and remains stationary, as it is fixed at both ends. A linear bearing with guide or rail assembly is required to support and guide the servo actuator and load.
The linear servo actuator simplifies the mechanical design of the system as it also eliminates the need for couplings, adapters, timing belts and gearboxes. In addition, it greatly reduces the labour time involved in assembling the system and does not require an air supply or a hydraulic power pack.
The motor frame size is available from 45mm to 100mm and the integrated ball screws or sliding screws are available from 6mm to 25mm. The systems can generate forces from 540N (55KGF) up to 3,920 N (400KGF) and can travel at speeds up to 3 metres per second. The Servo Motor Actuator provides fast, accurate and repeatable positioning which is difficult to obtain when using cylinders. Unlike typical ball screw applications, where the ball nut is fixed and the screw spins, the linear ball screw servo motor actuator system has the ball screw being fixed at both ends, while the ball nut rotates. This can eliminate the oscillations which occur in long ball screws at high speeds and which can cause vibration and bending of the screw. The system is also integrated into the frame of the machine, is self-contained and offers a small footprint compared to other technologies. Two Servo Motor Actuators can also be electronically synchronized together to lift or push simultaneously.
Due to the Ball Screw being fixed, a unique operational advantage can be obtained. Several linear servo motors can operate either independently or synchronized as they share the same ball screw, and which can function as a dual carriage actuator. This is very beneficial in applications where two linear servo motors are used in the Y axis, for example on CNC Gantry woodworking machinery, as this will increase production by offering double production parts, with two independent machining motions on a single work piece, with independent tool changing.
The linear ball screw servo motor actuator provides the high speeds of a belt drive with the high forces, precision, accuracy and repeatability of a ball screw slide.Read article