Encoders Application Analysis！

Encoders Application Analysis

Transmitting and receiving means photodetector devices are installed in the production site exposed many flaws in use, it has also internal factors external

Factors, mainly in the following aspects: 1. Transmitting device or receiving devices displaced or offset due to mechanical vibrations caused by other reasons, lead

The receiving apparatus can not be reliably received optical signal, and can not produce an electrical signal. For example; photoelectric encoder in rolling speed control system, because

Photoelectric encoder is bolted directly connected to the motor housing, optical encoder shaft through stiffer spring plate and the motor shaft

Then, because of the motor load is carried by the impact load, when the steel mills will cause excessive vibration of the motor shaft and the housing. It was determined; when crossing steel

Photoelectric encoder vibration velocity of 2.6mm / s, this may damage the vibration speed optical encoder internal functions. Resulting in error pulse, resulting in

Control system caused instability or malfunction, causing the accident.

2. Because the photodetector device is installed at the production site, production site environmental factors that lead to the photodetector device does not work reliably. As Ann

Loading site temperature, humidity, resulting in electronic component characteristics of the photoelectric detection means internal changes or damage. For example, in the continuous casting machine to send dummy track

System, since the position of the photodetector device is mounted near the slab, high ambient temperature, resulting in the photodetector means error signals or damaged

Production or lead to injury.

3. Various sources of electromagnetic interference of the production site, the interference generated by the photodetector means, resulting photodetector means output waveform distortion distortion

, Make the system malfunction or cause accidents. For example; photodetector means mounted on the body of production equipment, the signal transmitted through the cable to the control system

Distance system is generally 20m ~ 100m, although the transmission cables are generally used multi-core shielded cable, but the cable between the conductor resistance and line capacitance

Coupled with the impact of the same and other cable laying together, vulnerable to a variety of electromagnetic interference, thus causing waveform distortion, so that the anti

The deviation signal fed to the actual value of the speed control system, and cause the system accuracy.

(Ii) improvements

1. Change optical encoder is installed. Photoelectric encoder is not mounted on the motor housing, but produced a solid basis on motor

Fixed bracket to install an independent optical encoder, optical encoder shaft and motor shaft center height must be at the same level, the two-axis soft rubber

Or nylon hose connected to mitigate the impact of the load on the motor photoelectric encoder mechanical shock. After this manner by the vibrometer testing, the

Vibration speed was reduced to 1.2mm / s.

2. Reasonable choice photoelectric detector output signal transmission medium, shielded twisted-pair cable has replaced ordinary shielded cable. Shielded twisted-pair cable has

Two important technical characteristics, one of the cable by electromagnetic interference has a strong defense capability, because the electromagnetic field generating online

Interference current can cancel each other out. Another technical characteristics of shielded twisted pair cable is twisted after the mutual distance between the two lines is very small, two-wire lines from interference

From substantially equal to two wire shielded distributed capacitance network is basically the same, which is to suppress common mode interference effect is more obvious.

3. PLC software to monitor the use of or interference. In the continuous casting process requires the send dummy photodetector means for generating electrical signal timing in nature, while

Different stages of the signal corresponding to the entire process. Figure 5.

 


Before (1) send dummy process starts, photoelectric signal 1 is "1." (2) send dummy When the process starts, the A stage, roller starts, the starter rod

give away. When the dummy bar blocking the photovoltaic device emits infrared light, the photoelectric signal is "0"; when the infrared light through the dummy bar 2 small central hole

, The photovoltaic device signals 2 and 3 are "1." (3) send dummy process in B stage, optical signal is "0", stop roller, cited

The spindle pole suspend delivery, sector 10 of depression, and start straightening machine "sync 1" continues to send the dummy bar. (4) send dummy procedure in stage C,

Send starter rod, and no longer block the infrared light, optical signal 4 is "1", start the "sync 2" stop "Sync 1", continue on the dummy bar

give away. Thus the end of the photovoltaic device works. According to electrical operation of the optical detection device, as long as the site was measured during each send dummy photoelectric

Time signal generation, combining send dummy. The relationship between optical signals, and the use of PLC application data, prepared in accordance with the requirements of

PLC program, the PLC program output signal is input to the PLC input module, replace the original photoelectric signal of the input signal. Its block diagram shown six

Shown.

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