How to use stepper motor to drive cam indexer

In the opinion of Li'an Yin’s engineers, the rotary table machine uses the cam indexer drive source, and the ordinary gear reducer motor can fully meet the needs of use. There are also engineers who are proficient in using servo motors and stepping motors to drive the indexers. Here, stepping motors are used for the indexers. Let’s explain the situation.

Since a stepper motor is a device that converts electrical pulses into discrete mechanical motion, it has good data control characteristics. Therefore, a computer is an ideal driving source for a stepper motor. With the development of microelectronics and computer technology, software and hardware The combined control method has become the mainstream. This method generates control pulses through programs to drive hardware circuits. The single-chip microcomputer controls the stepper motor through software, and this kind of operation excavates the potential of the motor to a great extent. It is also an inevitable trend to use a single-chip microcomputer to control a stepper motor, and it also meets the current data requirements.

The stepper motor used by the indexer can be divided into reactive stepper motor, permanent magnet stepper motor, hybrid stepper motor, single-phase stepper motor, planar stepper motor and many other types in terms of its structure. Among the stepping motors used in the indexer, reactive stepping motors are the main ones. Li'anyin engineers believe that the operating performance of a stepper motor is closely related to the control method. Its control methods include: open-loop control system, closed-loop control system, and semi-closed-loop control system. Semi-closed-loop control systems are generally classified as open-loop or closed-loop systems in practical applications.

The so-called reactive stepping motor means that there are windings on the stator and the rotor is composed of soft magnetic materials. The structure is simple, the cost is low, the step angle is small, up to 1.2°, but the dynamic performance is poor, the efficiency is low, the heat is large, and the reliability is difficult to guarantee; the rotor of the permanent magnet stepping motor is made of permanent magnet material, and the poles of the rotor The number is the same as the number of poles of the stator. From the experience of Li'anyin engineers, it is characterized by good dynamic performance and large output torque, but this kind of motor has poor accuracy and large step angle (generally 7.5° or 15°); and the hybrid stepping motor is integrated In order to improve the accuracy of stepping torque, the advantages of reactive and permanent magnet types are achieved. The stator has multi-phase windings and the rotor adopts permanent magnet materials. Both the rotor and the stator have multiple small teeth to improve the stepping accuracy. It is characterized by large output torque, good dynamic performance, and small step angle, but its structure is complex and the cost is relatively high.

The method of selecting stepper motor and driver for cam indexer is to judge how big torque the indexer needs, because static torque is one of the main parameters for selecting stepper motor. When the disk driven by the indexer has a large load, a high-torque motor should be used. Similarly, when the torque index is large, the shape of the motor is also large. This point needs to be taken into account in space design; in addition, the required motor operating speed should be determined according to the rotational speed of the indexer. When the speed requirement is high, the motor with larger phase current and smaller inductance should be selected to increase the power input. And use a higher supply voltage when selecting the driver. Then, when choosing the installation specifications of the motor, it should be based on the specifications of the selected related brands, such as 57, 86, 110, etc., which are mainly related to the torque requirements. Regarding the positioning accuracy, it is not necessary to do too much consideration, because the accuracy of the indexer driving the turntable is not controlled by the driving source.

The above content is an engineer from Li'an, according to some generalizations and conclusions made by the automated turntable in selecting stepper motors, I hope it will be helpful to your automation design