272 – Thrust Analysis of Linear Actuator with a Curved Section

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Model Data


Linear motors are used for machine tools and similar devices because of their ability to exhibit high speeds, high acceleration and deceleration, in addition to high-accuracy positioning. Among them, linear actuators with curved sections also possess the ability to realize curved motions in addition to straight motions. High thrust that is also stable is required as a matter of improving performance, but because high thrust is affected by curved motion sections, prior investigations are necessary.
Differences in gap magnetic flux density between linear motion sections and curved motion sections can be difficult to comprehend in virtual calculations. High-accuracy estimations are possible through the use of FEM, which can take into account the effects of material non-linearity and magnetic flux leakage in space.
In this example, the thrust characteristics of a linear actuator with a curved section are obtained via analysis, and thrust at the transition from a linear motion to a curved motion is evaluated.

Thrust Characteristics

Thrust characteristics are shown in Fig. 1.
It is understood that thrust in the curved section is lower compared to the straight section. This is because, as shown in Fig. 2 and Fig. 3, the space between magnets becomes narrower on the inner diameter side of the curved section and widens on the outer diameter side, so the area where the rotor and the stator are situated opposite eachother is reduced, and the effective magnetic flux is also reduced.
It is understood that changes in the amount of thrust are large in the curved section. Similarly, as changes occur where the rotor and the stator are situated opposite eachother, the magnetic field of magnets becomes non-sinusoidal, but because coil magnetomotive force is a sine wave, this results in the generation of unintended thrust.

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