Band steel continuous hot galvanizing production line is divided into three parts including entrance section, process section and exit section according to technological process of production. The function of entrance section is to ensure continuity of steel tape to be sent to process section. The process section requires that the steel tape has constant operation speed, the zinc coating is thin and even; the exit section is to coil the steel tape after galvanization into coil and ensures continuous production. The characteristics are of hot galvanizing production line are: Long production line, a lot of transmission equipment, strict requirement on tension control, easy for steel tape to run off track; continuous production is necessary.
According to the technological characteristics of composition of the production line, DC transmission device selects Siemens 6RA70 or EUROTHERM 590 series full digital DC control device. Tension control of the coiling machine adopts special tension control module. PLC is S7-300/400 of SIEMENS Company. According to the composition characteristics of the production line, PLC system adopts one master station (S7-300/400) to drive three slave stations. Profibus communication bus is selected for communication among PLC.
(1) Manual and automatic control for steel coil transportation chain at the entrance.
(2)Manual and automatic control for transportation of steel coil trolley at the entrance including automatic unbaling, automatic measurement of coil diameter, automatic height centering, horizontal centering.
(3)Manual and automatic tape threading of tape head and tape end to the welding machine and automatic cutting of tape head and end.
(4)Calculation, control and speed matching of band steel filling degree at the entrance loop and exit loop.
(5) Instrument control function at the central section.
(6)Electric control function of central section.
(7)Automatic recoiling at the exit, automatic cutting of waste material and template.
(8)Automatic coiling and tape end positioning from exit section to the coiling machine.
(9)Transportation control, automatic weighing and bundling of steel coil trolley at the exit section.
(10)Weld seam tracking of the whole production line.
(11)Centering device control for band steel of the whole production line.
(12)Tension and speed control of the whole production line.
(13)Emergency stop of the whole production line.
A、 The linear speed for stable operation of every transmission equipment is identical.
B、 The band steel tension is balanced and stable in every tension interval, especially the band steel tension inside the heating furnace.
C、 According to its function, every group of S roller adopts control method suitable for it (tension type and speed type)
D、 Entrance loop and exit loop adopts double controls of constant loop length and constant tension.
E、 Entrance loop and exit loop adopts low oscillation control on the basis of constant loop length, which improves the tension precision of entrance section and exit section.
F、 EPC system of the coiling machine adopts sinusoidal, cosinoidal and trapezoidal wave control, which ensures the coiling quality of galvanized coiled stocks.