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Whether the cam indexer has repeated positioning accuracy,cam indexing mechanism

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Update time : 2019-06-16 18:47:59
The repeat positioning accuracy of the turntable is a topic that everyone pays more attention to. The accuracy error between the stations will affect some high-precision and high-speed automation systems. Therefore, in the indexer selection, engineers will ask the indexer. What is the repeat positioning accuracy? Xiaobian here gives a brief description of the repeat positioning accuracy of the cam indexer.
cam indexing mechanism
We will use the indexer to compare the positioning accuracy with the DD motor, the hollow rotating platform, etc. The DD motor is equipped with a high-resolution encoder and also uses a direct connection method, which greatly reduces the mechanical The various errors caused by the articulation of the structure are highly accurate in the existing rotary transmission equipment. For a hollow rotating platform, like a indexer, it does not have a driving function. It is driven by a servo or stepper motor. Therefore, for a hollow rotating platform, the repeat positioning accuracy we should talk about should be a servo motor. The repeating positioning accuracy, the servo motor is positioned by the pulse, the displacement of each station is the corresponding angle of rotation with the pulse received by the servo, and the servo motor sends a pulse to form a response with the received pulse, that is, we In the closed loop, the system controls the rotation timing of the motor according to the number of pulses received and the number of pulses received. It can be seen from the two ways of the above transmission that neither the encoder nor the pulse will be an absolute quantity, and each control will theoretically have a difference, although the error is small, but in one In the automation system, the accumulation of multiple station errors will amplify the overall error. Therefore, in actual use, the zero-return action must be performed to ensure the accuracy.
The cam indexer is also the same as the hollow rotating platform, and it has no driving function. However, the indexer has a function that neither the rotating platform nor the DD motor has, but the self-locking function. This self-locking comes from the curved surface. The structure of the cam, in the case of a single-lead indexer, the output shaft rotates one station per revolution of the input shaft. For each station of the output shaft, the input shaft completes a complete mechanical action, and The mechanical action of each input shaft is the same, so we say that there is no repeat positioning accuracy in the indexer. Then, for the indexer, there will be a difference between the error of the individual station and other stations. It can be seen from the angle measuring instrument during the factory measurement. That is because the cam roller on the output turret exists. Caused by minor differences.