ADT inverter in tension control
AD300 VFD used in Steel wire/tube rewinding production line
I. Brief introduction
OPGW optical cable is a special optical cable popular in recent years. Its fine usage and wide application make it have a wide market. Its production raw materials including stainless steel tubes, steel wires, aluminum alloy and aluminum-clad steel wires are usually supplied in reels of diameter 1 meter. While and the coils used on the OPGW line are 0.63 meters in diameter, so a rewinding machine is needed to rewind the raw materials into small reels of 0.63 meters.
ii Technical requirements and system composition:
1. Technical requirements: production line speed: ≥300m/min;
A: stainless steel tube: 10N ≤ F ≤ 50N;
B: steel wire, aluminum-clad steel wire: 100N ≤ F ≤ 250N;
C: aluminum alloy wire: 50N ≤ F ≤ 150N;
Metering accuracy: 0.2%;
Cable laying speed: automatically track the rewinding speed;
2. System composition (electrical part):
The cable rewinding, laying, and unwinding(payoff) all use variable frequency drives to control. The system uses AD300 series AC drives, Siemens TP-070 HMI, and Siemens S7-226 EM-231 controller. S7-226 Port 0 is used to communicate with AD300 AC drives by Modbus and Port 1 communicates with TP-070 HMI.
iii the introduction of each part of control
1. Rewinding speed control
The rewinding machine is used to rewind the steel wire and steel tube. The motor drives the screw rod to make the tape open & close, and up & down. Common AC asynchronous motor and contactor is used and the rewinding motor is controlled by AD300 series frequency inverter. The rewinding speed signal is sent from EM-231 to S7-226 and finally send to AD300 via Modbus communication. Due to the production line speed is high, the reel tape has relatively high rotational inertia, so the rewinding acceleration speed should not be too high. PID calculation function is used for rewinding speed setting. And the rewinding reel tape is using high speed balanced tape. AC drive model: AD300-T47R5GB/011PB.
2. Wire diameter control:
Since the cable laying speed needs to automatically track the wire take-up rewinding speed according to the wire diameter (U=K*ω*D).
Where U: cable laying speed, K: correction coefficient, ω: rewinding speed, D: wire diameter
Therefore, the setting of the cable laying motor driver is determined by the following two factors:
The rewinding speed is measured by a rotary encoder. The signal is sent to the PLC (high-speed counter 4) through I0.6 and I0.7 of S7-226. The PLC program uses the timer interrupt to measure the count value of the high-speed counter in unit time as the rewinding speed.
The wire diameter value is set by TP-070 and sent to the PLC. The PLC multiplies the above two parameters and multiplies the corresponding correction coefficient (determined according to the mechanical gear ratio) to get the cable laying speed. The cable laying speed is fed through the Modbus protocol to AD300 AC drives.
It should be noted that since the cable laying motor needs high-speed reversing. So when the reversing signal is received, the motor needs high-speed deceleration and fast speed-up process. AD300 VFD needs to use inbuilt brake unit and the external braking resistors. Inverter model: AD200=T4R75GB/1R5PB
3. Payoff reel tension control:
On the entire production line, the coil-up motor determines the line speed, and the tension is determined by the pay-off motor. Due to the higher tension requirements, the un-coiling needs to be actively operated.