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Driving a cam indexer with a stepper motor-rotary indexer

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Update time : 2019-06-28 21:54:45
In the engineer's view, the rotary disc machine uses the cam indexer drive source, the ordinary gear reducer motor can fully meet the needs of use, and some engineers who are skilled in using the servo motor and stepper motor to drive the indexer, here use stepper for the indexer The case of the motor will be described below.
Since the stepping motor is a device that converts electric pulses into discrete mechanical motions and has good data control characteristics, the computer is an ideal driving source for stepper motors. With the development of microelectronics and computer technology, hardware and software The combined control method has become the mainstream. This method generates control pulses through the program and drives the hardware circuit. The single-chip microcomputer controls the stepping motor through software, and such operation has largely excavated the potential of the motor. It is also an inevitable trend to control the stepping motor with a single-chip microcomputer, which is also in line with the current data requirements.
rotary indexer
The stepping motor used in the indexer can be divided into reactive stepping motor, permanent magnet stepping motor, hybrid stepping motor, single-phase stepping motor, plane stepping motor and the like from its structural form. The stepping motor used in the cam indexer is mainly a reactive stepping motor. Engineers believe that the running performance of stepper motor is closely related to the control mode. Its control methods include: open loop control system, closed loop control system, semi-closed loop control system. Semi-closed loop control systems are generally classified in open loop or closed loop systems in practical applications.
The so-called reactive stepping motor refers to a winding on the stator, and the rotor is composed of a soft magnetic material. 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 ensure; the rotor of the permanent magnet type stepping motor is made of permanent magnet material, and the pole of the rotor The number is the same as the number of poles of the stator. From the experience of engineers, it is characterized by good dynamic performance and large output torque, but the accuracy of this motor is poor, and the step angle is large (typically 7.5° or 15°); and the hybrid stepping motor combines the reaction. The advantages of the type and the permanent magnet type are that there are multi-phase windings on the stator, permanent magnet materials on the rotor, and a plurality of small teeth on the rotor and the stator to improve the step precision. The utility model has the advantages of large output torque, good dynamic performance and small step angle, but the structure is complex and the cost is relatively high.
The method of selecting the stepping motor and the driver by the cam indexer is to judge how much torque the indexer needs, because the static torque is one of the main parameters for selecting the stepping motor. When the load of the disc driven by the indexer is large, a large torque motor should be used. Similarly, when the torque index is large, the shape of the motor is also large, and this point needs to be taken into consideration in the space design. In addition, the demand motor is determined according to the speed of the indexer. Operating speed, when the speed requirement is high, the motor with larger phase current and smaller inductance should be selected to increase the power input. A higher supply voltage is used when selecting the driver. Then, when selecting the installation specifications of the motor, it depends on the specifications of the selected brand, such as 57, 86, 110, etc., mainly related to the torque requirements. For positioning accuracy, it is not necessary to consider too much, because the accuracy of the indexer drive dial is not controlled by the drive source.
The above content is an engineer, based on the induction and summary of the choice of stepper motor in the automatic rotary machine, I hope to help your automation design.