Absolute encoder selection, installation and adjustment

Rotary encoders include absolute encoders and incremental encoders, which are widely used in the field of industrial control. Designers will choose the appropriate rotary encoder application according to their own design requirements. The absolute value encoder uses a highly concentrated rotating disk as the basis to help the equipment complete the signal measurement, so what should we pay attention to in the selection, installation and adjustment of the absolute value encoder?

First, the choice of the material of the absolute encoder shell

For absolute encoders, the material of the outer shell is very important. It is not only the foundation of the encoder's environmental adaptability, but also the guarantee for the protection of various internal components. With the improvement of current technology, the housing materials of encoders have begun to diversify. Nowadays, a major trend is to use rare earth alloy materials as the basis of the housing. The advantages of rare earth materials are that they have good strength and sealability. Even better, can help the equipment better adapt to different industrial environments. The details that need to be considered in the process of selecting the shell material are the grasp of the shape and size.

2. Absolute encoder performance is in place

There are many items that need to be considered for the performance of an absolute encoder. The first is the signal conversion method. Different encoders have different characteristics in signal conversion. The encoder uses the internal rotating disk to divide it into four. The difference between each adjacent part is 90 degrees. This can help the device to obtain the signal direction more accurately while the signal measurement is converted. The signal can be well transmitted through the groove during operation. The beam is hit on the rotating disk, and the signal parameters can be obtained through the pre-drawn partitions. In the process of absolute encoder design, the biggest difficulty is to do a good job of connecting different signals and the rotating disk.

3. Installation method of absolute encoder

In the process of designing the absolute value encoder, the installation method is also one of many details. It is in the use and installation of the equipment, so for the consideration of different use spaces, the absolute value encoder can be divided into two methods: base installation and flange installation. , The difficulty of design lies in the connection between different installation methods.

Four, absolute encoder reference point adjustment

Absolute encoder reference point adjustment 1

Normally, only need to perform a calibration at the first start-up, the system will know the value and can calculate the absolute machine position through the absolute value of the encoder at any time. The offset is stored in MD34090REFPMOVEDIST-CORR. It must be recalibrated when the following situations occur:

①After removing, installing or replacing the encoder or the motor with the encoder inside;

②After the motor (with absolute value encoder) and the load are shifted;

③ When the extreme connection between the encoder and the load is disconnected and has not been reconnected.

When the CNC system is powered on and the corresponding feed axis is identified, it will automatically use the absolute encoder to return to the reference point. The axis movement does not occur when receiving the absolute value. For example, when the power is turned on, automatic reference point return must meet two prerequisites:

① The feed axis uses an absolute encoder to control the position;

②The absolute encoder has been calibrated (MD34210ENC-REFP-STATE=2).

When the feed axis is equipped with an absolute encoder, the measurement system does not need to be synchronized by returning to the reference point stop. However, if the correction method is adopted, the actual value set during the system debugging is accepted by the system. The absolute encoder returns to the reference point, moves the feed axis to be corrected to the given position, and then sets the actual value. The general steps for correction are as follows:

①Set MD34200ENCREFP-MODE=0 and MD34210ENC-REFP-STATE=0, and then power on again to enable. The parameter ENC-REFP-MODE=0 means that the actual value of the feed axis has been set.

②In JOG mode, manually feed the axis to the known machining origin position. The direction of position feed must follow the setting in MD34010_REFP_CAMDIRISMINUS (0=positive direction, 1=negative direction).

③Set MD34210ENC—REFP—STATE=1, press reset to enable the modified machine data. Change to JOG-REF mode, press the run key ("+" or "-"), the current offset is automatically set to MD34090REFP_MOVE-DIST-CORR, MD34210ENC-REFP-STATE=2, that is, the axis has been calibrated. The system cannot find all situations that need to be recalibrated. If the system finds certain conditions, it will set the value of machine data MD34210 to 0 or 1. The system can recognize the following situations: a gear shift, which has a different gear ratio between the encoder and the load. In other cases, the user must overwrite the machine data MD34210.

Data saving also saves the state of MD34210ENC-REFPSTATE. By loading this data record, it indicates that the feed axis has been automatically calibrated. If the data record comes from other machine tools (such as serial debugging machine), after the data is loaded and enabled, it must be corrected.

Absolute encoder reference point adjustment 2

① In JOG mode, manually feed the axis to the known machining origin position. The direction of position feed must follow the setting in MD34010_REFP_CAMDIRISMINUS (0=positive direction, 1=negative direction).

②Set MD34210ENC—REFP—STATE=1, press reset to enable the modified machine data. Change to JOG-REF mode, press the corresponding run key ("+" or "-") according to the MD34010 parameter value in ①, the current offset is automatically set to MD34090REFP_MOVE-DIST-CORR, MD34210ENC-REFP-STATE=2, that is The axis is corrected.