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cause changes in thickness. Coupled with the recent implementation of heat from the equipment, direct rolling, rolling control, such as further energy conservation point of view, finishing unit entrance thickness of a thickening tendency, so the thickness of the automatic control system of increasingly stringent requirements.
3 .Finishing exports gage
Exports are finishing the installation of two gage, two spare each other. When PSU function input, through the L2-gage to set up the computer when the PSU functions abolished, by HMI to set up the gage. Gage online test strip thickness of the export bias through PLC309 will thickness deviation and other state signal read, after dimensional conversion, and then sent to TPL and Ethernet network.
4 .Thickness of automatic control
Hot rolling mill unit finishing the HAGC control system locked AGC, maintain AGC, AGC control and monitoring of AGC locked automatically lock function in order to improve strip-plate thickness of poor accuracy and number of products-plate thickness of poor consistency. Its classification as follows: pressure AGC: locked AGC, maintain AGC, AGC absolute control AGC: Monitoring AGC, locked AGC, AGC automatically locked in addition to monitoring AGC automatic locking function, the above-mentioned AGC control by the Rolling operatives choice, control AGC feature Individual investment, and should normally be at the same time put pressure on the AGC for good.
4.1 Thickness control system
4.1.1 Locked AGC
AGC is locked rolling force for the process variable, with spring equation calculated strip thickness, its calculation method, see-(4.1). Under the control of the strip thickness of the benchmark is locked Strip by the thickness of the head. Strip thickness locked in two ways, a
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bite of a rack to lock automatically after the delay, and the other is finishing mill when the exit of the gage after the seizure of the rack at the same time lock. Such control only the thickness of rolling strip effective.
hi = (Pi-Po) / Mi + Si (4.1)
hi: strip thickness (mm)
Pi: Rolling measured force (t) Po: Rolling zero-pressure (t) Mi: Mill stiffness (t / mm) Si: Roll Gap measured (mm)
δ hi = href-hi (4.2) δ hi: strip thickness deviation (mm)
href: The head lock block strip thickness (mm) hi: strip thickness (mm)
href = (Phead-Po) / Mhead + Shead (4.3) Phead: strip head measured rolling force (t); Po: Mill zero-pressure (t); Mhead: strip head Mill stiffness (t / mm)
Shead: strip joints measured head roll (mm)
4.1.2 Maintain AGC
AGC is the pressure to maintain a variant form of AGC, strip thickness of the benchmark is to choose the head to maintain the pre-lock function AGC AGC locked strip thickness of the head benchmarks, the aim is to maintain the number of strip-plate thickness and the poor in line Sexual. When the lock with AGC function rolling, and rolling conditions are relatively stable, may choose to use this feature. Thickness calculations are as follows: hi = (Pi-Po) / Mi + Si (4.4) hi: strip thickness (mm)
Pi: Rolling measured force (t) Po: Rolling zero-pressure (t) Mi: Mill stiffness (t / mm) Si: Roll Gap measured (mm)
δ hi = href-hi (4.5) δ hi: strip thickness deviation (mm)
href: AGC lock lock strip head lock thickness (mm) hi: strip thickness (mm)
4.1.3 Absolute AGC
Computer calculations to set the goal of controlling the thickness as the target thickness, and lock the rack rolling forecast of automatic thickness adjustment, the actual pursuit of strip thickness of the finished product with the requirements of the minimum thickness as the goal difference. The rack after the bite of a certain amount of time delay t (delay time set by the software, about 200 ms, the scene again when debugging), in this time delay calculation N (a scan cycle once) the first strip Department of rolling average of P * [P *= (P1 +… Pn) / n] Roll Gap average value of S * [S *= (S1 +… Sn) / n], the average strip thickness h * [h *= (h1 + … Hn) / n].
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If the calculation of the average strip thickness h and given the objectives of the difference between the thickness of hmp not exceed a certain limit △ hJX (by software settings), hmp-h <△ hJX, set the computer to process the goal of calculating the thickness As the target thickness control. If the calculation of average thickness of the strip and to the thickness of the objectives of the difference over a certain limit △ hJX (set by the software), will head the rack strip rolling average of P *, the average value of Roll Gap S * value as a lock, that is absolutely AGC automatically switch to the relative AGC. In order to avoid substantial adjustment due to roll joints, rolling impact of state stability. At the same time the alarm signal sent HMI screen. AGC absolute control mode, the strip thickness of the head of the baseline calculation used by the rolling pressure from the finishing mill in the process of the computer is set up pressure, strip thickness calculations are as follows.
hi = (Pi-Po) / Mi + Si (4.6)
hi: strip thickness (mm) Pi: Rolling measured force (t) Po: Rolling zero-pressure (t) Mi: Mill stiffness (t / mm) Si: Roll Gap measured (mm)
δ h = href-hi (4.7) δ h: strip thickness (mm)
href: strip thickness deviation (mm)
hi: the head of the block strip thickness (mm)
href = (Phead-Po) / Mhead + Shead Phead: Computer set rolling strip head of the forecasting value (t) Po: Mill zero-pressure (t)
Mhead: strip mill head stiffness (t / mm) Shead: strip joints head roll (mm)
4.1.4 Monitoring AGC
Monitoring AGC control is based on finishing mill exports gage measured by the thickness of the strip samples average deviation of the rack to fix the export thickness of the workpiece. Rolling process, monitoring the AGC gage measured by the thickness of the strip samples to the average deviation, then under the F4, F5, F6 three rack state, according to the latter calculation of the distribution of various controlled rolling rack Thickness. Calculated as follows:
1) strip thickness of sample calculation of average deviation
?j???hji/nj
i?1nj?j: J-strip samples thickness average deviation (mm)
δ hji: gage measured the j-i, the first sample strip thickness deviation (mm) nj: j-section sample of the length of the strip sampling frequency 2) that monitor the distribution of
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MFi =?j-Maxi
MFi＝＋Maxi ?j≥＋Maxi
?j: J-strip samples thickness average deviation (mm)
MFi: first i rack monitoring rectification (mm)
- Maxi: first i rack that monitor the smallest amount (mm) + Maxi: first i rack that monitor the smallest amount (mm) i: Rack, finishing mill, i = 4,5,6
AGC is monitoring the head arrived in the Strip District, as gage after a certain delay after t (delay time by the Software settings, the scene again when debugging), finishing exports through the acquisition gage thick poor, calculated average, AGC control logic by monitoring and control of distribution algorithm, decided to monitor the AGC in the roll seam-rack Festival value.
① Monitoring Algorithm
In the latter defined by the sampling period, the calculation of the export gage finishing the strip to detect the thickness deviation - Mean △ hpj, then roll joints for the regulation of:
△ SMi = K1K2 △ hpj (4.10)
K1: ratio coefficient, to eliminate bias in the thickness of units required for rack-Fi Roll Gap adjustment;
M?Q K1? (4.11)
MWhere: M for the mill stiffness, Q factor for the rolling pieces of plastic.
K2 ratio factor, since Fi rack to gage the transmission lag, if the workpiece delivery time for ti,
K2 for the stability of the system should be less than 1 / 2 ti, taking into account the reduction agencies also lagged behind, hydraulic pressure fast response, from
K2 = (1 / 2 ~ 1 / 4) ti, specific parameters to be determined at the scene debugging. ② determine control of the cycle
Control cycle should be greater than or equal to workpiece control points to gage the time ti.
Workpiece control points to gage the time ti is calculated as follows:
1) The F6 stand: ti?S0 VLS05S2) The F1-F5 rack: ti???
VLJ?1VIType in: S0 at the end of the rack to gage the distance between, VL sampling for the
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moment at the end of rack rate, S for the provisional phase
The distance between the two racks, Vi sampling for the moment Fi rack rate. ③ monitoring AGC basic steps to control
Gage head arrived in the Strip District as a certain delay after t (delay time set by the software),
AGC automatic monitoring.
If the export of finishing gage measured the thickness difference | △ h | ≦ dead value (dead value set by the software), AGC is not regulated. If | △ h |> dead value, calculated roll gap adjustment of△s. If the roll seam-conditioning in | △ s | ≦ Smi (SFi is a cycle of mining-Fi rack to allow adjustment of roll joints), the only adjustment Fi rack pressure if roll gap adjustment of | △ s | ≥ Smi, then Fi rack roll joints for the regulation of Smi, roll seam-conditioning cushion by a control logic and distribution assigned to monitor the upper reaches of AGC input rack. Distribution, see Schedule. According to AGC to participate in monitoring the rack, according to the actual rolling speed, when the rack deformation zone gage steel exports reached, the beginning of a new mining cycle control.
4.1.6 Monitor automatically locked AGC
Such control is not a choice of operatives, as long as the AGC function in monitoring and control system in the first sample strip thickness deviation averages determine whether at the end of input. For example, when the first sample strip thickness deviation average of absolute value greater than 0.1 mm results, monitoring AGC automatic locking function that is now in control of AGC to be -0.1 mm or 0.1 mm on the basis of control. Otherwise, strip-board ultra-poor of the poor will be too long. This function of control is very significant, when the head of the computer precision partial set at the end of this block can guarantee that the steel-plate ultra-poor is not poor. This feature, and monitoring functions of the same AGC locked, the only difference is that control of AGC to lock automatically without intervention, are fully automatic control system completed.
4.4.4.6 Support roller bearing oil film thickness compensation
Film roller bearings supporting the film thickness is with the pressure and speed of change, the value of rolling pressure to reduce the increase; Roll With the increase in the speed increase, so it is a dynamic variable roll gap, up to the changes in film thickness 200-400μ. Its influence through the correction DAGC gaps of 0.1 to achieve compensation. Film thickness and pressure and speed:
Na*P ?Sl?Of?N?bPWhere: Of :a film thickness (mm); N :Roll speed (r / min); P: a rolling pressure (kN); a :constant;
b:a constant (r / min.kN)
N, P can be measured by mechanical pressure on law change to the roll gap and the number of experiments on the mill can be drawn from a, b constant. Its measurement methods