Title: Basic Guidelines and Methods for Selecting Linear Motors

Linear motors possess unique usage characteristics that cannot be replaced by rotary motors. However, not every situation warrants the use of linear motors to achieve optimal results. Therefore, it is essential to first understand the basic guidelines for selecting linear motors in order to use them appropriately. These basic guidelines consist of the following four key points.

1. Appropriate Motion Speed The motion speed of a linear motor is related to the synchronous speed, which is directly proportional to the pole pitch. Thus, the range of pole pitch selection determines the range of motion speed selection. A pole pitch that is too small will reduce slot utilization, increase slot leakage reactance, decrease the quality factor, and consequently lower the efficiency and power factor of the electric motor. The lower limit for pole pitch is typically set at 3cm. While there may not be an upper limit for pole pitch, when the output power of the motor is fixed, the longitudinal length of the primary core is limited. Additionally, in order to reduce longitudinal edge effects, the number of poles in the motor cannot be too few, hence the pole pitch cannot be too large.

2. Appropriate Thrust Rotary motors can adapt to a wide range of thrust levels. By pairing a rotary motor with different gearboxes, varying speeds and torques can be obtained. In low-speed scenarios, torque can be increased by several tens to hundreds of times, allowing a small rotary motor to drive a large load, while conserving power. In contrast, linear motors cannot alter speed and thrust using a gearbox, thus their thrust cannot be expanded. To achieve a relatively large thrust, one must rely on increasing the size of the electric motor, which may sometimes be uneconomical. Generally, in industrial applications, linear motors are suitable for driving light loads.

3. Appropriate Reciprocating Frequency In industrial applications, linear induction motors undergo reciprocating motion. To achieve higher labor productivity, a higher reciprocating frequency is required. This means that the motor must complete the stroke in a shorter period of time, experiencing acceleration and deceleration within one stroke, i.e., starting and stopping once. A higher reciprocating frequency results in greater acceleration of the motor, corresponding to a higher thrust. Sometimes, the thrust corresponding to the acceleration may even exceed the required thrust of the load. The increase in thrust leads to an increase in the size of the electric motor, and the increased mass further raises the thrust corresponding to acceleration, sometimes leading to a vicious cycle.

4. Appropriate Positioning Accuracy In many application scenarios, the motor stops moving when it reaches the designated position due to mechanical limit stops. To minimize impact upon reaching the position, a mechanical damping device can be added. In cases where there are no mechanical limit stops, a simple positioning method involves controlling the motor through travel switches before reaching the position, applying reverse braking or regenerative braking to stop it in place.

In conclusion, understanding and adhering to these basic guidelines for selecting linear motors is crucial for utilizing them effectively in various applications. By considering factors such as motion speed, thrust, reciprocating frequency, and positioning accuracy, one can ensure the optimal performance of linear motors in their intended use cases.