What is the Spindle Encoder?

Spindle encoder is one of the parts of many advanced CNC machines. It is mainly used to measure the rotation speed of the main shaft and is installed on the main shaft to detect components. When the spindle encoder is used in the threading of the CNC lathe, it uses its synchronization pulse as the control signal of the turning tool's feed point and the tool retreat point, so as to ensure that the turning thread will not be buckled indiscriminately. Today we will talk about the spindle encoder product.

The role of spindle encoder

Usually the spindle encoder device adopts a photoelectric pulse generator synchronized with the spindle, and transmits 1:1 synchronously through the gear on the intermediate shaft. There is no direct mechanical connection between the rotation of the spindle of the CNC lathe and the feed movement. In order to process the thread, it is required that the pulse number of the given servo motor and the speed of the spindle should have a corresponding relationship. The spindle pulse generator has the effect on the connection between the spindle rotation and the feed movement. 

Precautions for the selection of spindle encoder

Usually three parameters should be paid attention to when selecting spindle encoder component.

1. Mechanical installation dimensions, including positioning stop, shaft diameter, installation hole position, cable outlet method, installation space volume, and whether the working environment protection level meets the requirements.

2. Resolution, that is to say, when the encoder is working, whether the number of pulses output per revolution meets the design and use accuracy requirements. 

3. Electrical interface. Encoder output methods commonly include push-pull output (F type HTL format), voltage output (E), open collector (C, common C is NPN type tube output, C2 is PNP type tube output), long-line driver output. Its output mode should match the interface circuit of its control system. 

Mechanical part

1. Length measurement or angle measurement, how to convert length measurement by mechanical means. Is the measured angle within 360 degrees (single lap) or over 360 degrees (multiple laps)? The production process is a rotation cycle work in one direction, or a cycle work in a back and forth direction?

2. Shaft connection installation form, whether there is a shaft type connected by a flexible coupling, or a shaft sleeve type connection.

3. Use environment: it includes whether the environment has dust, moisture, vibration, impact etc.

Electrical part

1. The output and receiving part of the connection.

2. Signal form.

3. Resolution requirement.

4. Control requirement.

In addition, you need pay attention to that the conventional shape of absolute encoder device is 38MM, 58MM, 66MM, 80MM and 100MM.The absolute encoder accuracy includes single-turn accuracy and multi-turn accuracy, which add up to the total accuracy, that is to say, the usual number of bits, and the normal number is 24bit, 25bit, 30 bit, 32 bit etc. The absolute encoder communication protocol baud rate is 4800~115200 bit/s, usually it is 9600 bit/s, and encoder refresh cycle is about 1.5ms. Optional encoder output is SSI, 4-20MA, profibus-dp, DEVicenet, parallel, binary code, BESM58, BiSS, ISI,CANopen, Endat, Hiperface etc.