The Model Server is the Level 2 automation system consisting of a mill process computer. The mill process computer based on mathematical models and strategies, calculates the set up values for the mill like roll gap, roll force, CVC position, bending values etc., (in association with the slab data and transfer bar data). Finally the set up values allow for an accurate control of strip thickness, profile and flatness.
The area of the model server is restricted to the Steckel Mill stand and coiler furnace. The primary data is transmitted by the production control PC to furnace PLC.
When a slab is discharged from the furnace, furnace PLC transmits the primary data of this slab and the next slab to Roughing Mill PLC. After acknowledgement from Roughing Mill operator, Roughing Mill PLC transmits the primary data to model server.
With the completion of the last pass in the Roughing Mill, Roughing Mill PLC transmits the actual values of the last pass in the Roughing Mill, (Width, last pass roll force, roll gap, temperature and speed) to model server.
The availability of primary data and T-bar data enable the model server to calculate the pass schedule. After the calculation, the set up values are transmitted to the Steckel Mill PLC. The Steckel Mill PLC will do the sequence control of the process in Steckel Mill. During the pass in Steckel Mill, actual values like roll force and strip temperature are measured by Steckel Mill PLC and sent to Model server.
After 35-50% of that pass length is rolled the model server will process the measured values sent by Steckel Mill PLC. Based on this feed back, the models will re-calculate an improved set up for the remaining passes. However, the thickness distribution, speed, tension values will not be changed. This process will be repeated pass by pass until the last pass is reached.
The model server has the following automation functions:
1. Strip tracking
2. Pass schedule calculation
3. Acquisition and processing of measured values 4. Dialogue and display
5. Logging function.
Roll shop
Roll Shop caters to the
Work rolls and back up roll requirements of Roughing Mill and Steckel Mill by supplying rolls with chocks assembled with bearings as and when required.
Turning and assembling of Edger rolls.
Grinding of Pinch rolls of Steckel Mill and Down Coiler.
The used work rolls, back up rolls of Roughing Mill and Steckel Mill, Edger rolls and Pinch rolls of Steckel Mill and Down Coiler are reground in the Roll grinding machine.
Roll grinding m/c is supplied by M/S Toshiba machine company, Japan.
State – of –the- art CNC roll grinder is working on Level -3 automation which ensures fully automatic grinding where special functions like wheel quick approach, Automatic roll alignment and wheel surface speed control are done by machine itself.
Overhauling and maintenance of all Work roll and Back up roll bearings are taken up on a regular basis. The chocks earmarked for overhauling are dismounted from rolls. Then the bearings, seals and chock internals are taken out, cleaned and checked for any mark or wear and tear. Based on the condition, the bearings and chock internals are either replaced with new or are put back after thorough cleaning and removal of marks.
Roll Grinding Machine (RGC 1400 x 5000 CNC grinding machine)
Hot Rolling Mill (HRM) of Salem Steel Plant have different rolls like Breakup Rolls, Work rolls, Edger Rolls and Pinch Rolls. All these Rolls in HRM need grinding after a stipulated tonnage of rolling for better surface finish. So, these rolls are being ground by CNC grinding machines.
In HRM, in addition to the existing CNC grinding machine supplied by M/S Toshiba, a new Roll grinding machine of Type: RGC 1400 x 5000 CNC, [supplied by M/S World Machinery Works (WMW), Romania] was also commissioned in July 2009 to grind HRM rolls for production of 3,70,000 t of Slabs per year.
The main equipments and automation of this new Roll Grinding Machine
a. CNC : SINUMERIK 840D
b. MIDA : Roll Alignment System
c. MARPOSS : Wheel Balancing and auto wheel touching d. LISMAR : Flaw detection
e. Meas4 Roll : Profile measurement f. Wheel measurement and dressing
g. PLC : SIMATIC S7-300
This machine consists of mainly 9 axes. The details are as follows C1 : Roll drive rotation
C2 : Wheel Rotation
Z : Longitudinal Movement of the Carriage
X : Traverse Movement of grinding wheel (coarse) X1 : Traverse Movement of grinding wheel (fine) B : Wheel assembly swiveling
A : Diameter measurement arm rotational movement Y : Diameter measurement
U : Roll alignment
Special features of RGC 1400 x 5000 CNC grinding machine
The roll grinding machine RGC 1400 x 5000 CNC type performs grinding, measuring and testing E.C cylindrical surfaces, Plane or Cambered (concave or convex).
Highly productivity output ranges, optimal machine accuracy and decreasing preparation period.
All types of profile can be ground Viz. Straight, Taper, Concave, Convex, Radius, CVC etc.
Backup Rolls and Edger Rolls can be ground with chocks
Roll diameter can be measured during grinding
Grinding accuracy
- Roundness : 0.002 mm - Cylindricity : 0.002 mm - Crown profile : 0.0025 mm - CVC profile : 0.0025 mm Down coiler
The finished strip from Steckel Mill rolling is coiled around the Down Coiler mandrel.
The finish strip thickness:
For Carbon steel : 1.60 mm to 12.7 mm For Stainless steel: 2.00 mm to 10.0 mm
The equipments are supplied by M/S Schloemann Siemag (SMS), Germany. The automation is done by M/S Siemens, Germany. The Down Coiler is controlled by
Level -1 automation. The walking beam conveyor is used for the transportation of coils to the Coil Yard. The coil is strapped by a single band circumferencial automatic Strapping machine, weighed in the weighing m/c and marked by an automatic marking machine supplied by M/S Infosight Corporation, USA.
Down Coiler consists of
a. Run out Roller table (RORT): This consists of 184 rollers (Roll dia: 300 mm) separated into six groups. This helps in transporting the finished strip from Steckel Mill to Down Coiler
b. Side Guides: Side guides are provided for guiding the strip straight into the Coiler.
c. Hold Down Roll: The main function of the hold down roll (Roll dia: 300 mm) is to avoid fluttering in the strip. This roll will be in the up position when the strip is coming and will get down when the strip enters the pinch roll.
e. Strip Switch: The strip switch guides the strip to the mandrel. During coiling it opens and it allows the strip to the mandrel and afterwards it closes the way to the mandrel.
f. Chute Plate: The chute plate feed the strip to wrapper roll 1 which makes the strip to wind on the coiler
g. Wrapper Rolls: Three wrapper rolls are provided for wrapping the head end of the strip into the mandrel. The wrapper rolls will get retracted after the mandrel expanded and tension built.
h. Mandrel: The finished strip from Steckel Mill winds on the mandrel The diameter of the mandrel:
Collapsed : 727 mm Pre-expanded : 738 mm Fully expanded: 762 mm
i. Outboard Support Bearing: Two support bearings are provided, one in right and the other in the left side to hold the mandrel during rolling.
j. Coil Car: The coil car transports the finished coil from the mandrel to the walking beam conveyor. It has a lifting table which is provided with two rollers and locking provision for the rollers.
5.2CRM-COLD ROLLING MILL Input
Hot Rolled Stainless Steel Coils from HRM of SSP.
Imported source Hot Rolled Coils (430 grade Coils).
Process
SSP employs the latest technology in cold rolling and incorporates the most modern equipment supplier by the leading machinery manufacturer all over the world.
The raw material for CRM is HR Stainless Steel Coils, called hot beams. These coils are processed in Coil Built-up Line (CBL). Coils from CBL are softened and descaled in Annealing and Pickling Line (APL. From here they are sent for cold rolling in Sendzimir Mill (Z-Mill) to the descried final thickness.
The cold Rolled Coils are again softened and descaled to obtain the optimum finish and mechanical properties. These are passed through the Skin Pass Mill (SPM) to give a bright finish and necessary flatness. The coils are ultimately either slit or sheared into finished products in the form of slit/divided coils or cut-lengths. The special surface finishes are obtained in the Sheet Grinding and in the form in the Strip Grinding Line (SGL).With the special feature of the computerized gauge control in Sendzimir Mill, it is possible to obtain very close gauge tolerances. The Ruthner neutral electrolytic pickling process in the APL ensures excellent surface finish and minimum environmental pollution.
Units in CRM
Cold build up line
Bell annealing furnace
Annealing and pickling line no:2
Annealing and pickling line no:1
Strip grinding line
Shearing lineStrip grinding and polishing line
PROCESS FLOW :COLD ROLL MILL