REPRESENTATION OF FLYING SHEAR “C” PROGRAMME AS

ALGORITHMS

Breakdown mill Input: 320*250mm 6m length bloom from SMS Output : 125*125mm 32m length Billet

Bar mill Input : 125*125mm 30m length Billet Output : Plain Bars and Rebars, Angles, Channels etc... Two Walking beam Furnaces. Break down mill is a 7 stand rolling mill. Flying Shear is used for cutting the billet into desired lengths. 10m Billet goes to Wire rod mill and 30m Billet goes to Bar mill for

further size reduction. Bar mill is a three stage mill.

Roughing train is a two strand mill consists 8 stands 2 Intermediate trains each consists 5 stands 2 Finishing Trains each consists 4 stands with loopers Two cooling beds 7 Strapping machines for two lines(Machine 7 is spare)

LMMM at a glance

To cut Head & tail ends of the billet

To perform Part length cuttings of Billets to the desired length

To perform emergency cutting of Billet into 5 or 8m

PURPOSE OF FLYING SHEAR

POWER CIRCUIT 11KV

405KVA11KV/325V

T1050 N2400

HSCB 292KA

DC CONTACTOR

186KW,230V,884A,435rpm

6KVA415/400V

186KW,230V,884A,435rpm230V,8.8A

230V,8.8A

SHEAR FORCE: 2100kNKNIFE CIRCLE: 800mm diaGEAR RATIO : 5.136OPERATING MOTOR SPEED:0-280rpmKNIFE SHAFT SPEED: 0-54rpm

LOCATION OF FLYING SHEAR

REST POSITION/BASIC POSITION

ACCELERATION DECELERATION

IN MAT POSITION OUT MAT POSITION

MATERIAL DIRECTIONSEPARATING POSITION

VOLTAGE

TIME

AC

CELE

RATIO

N

DEC

ELE

RATIO

N

a a

bc

dLEAD

PHASES OF THE SHEAR

AUTO MODE

• Phases of the Shear:

REST POSITION/BASIC POSITION

ACCELERATION DECELERATION

IN MAT POSITION OUT MAT POSITION

MATERIAL DIRECTION

+33

0

-33

+500 -500

Main function has 2 sub functions:1. EventDispatcher2. AuxRefValue Gen

EventDispatcher: Billet enter stand 3: Executes only when1. Stand 3 should be running2. Stand 3 current should be high and stable3. Billet in stand3 should be in reset state.

ALGORITHM IN BLM1

Algorithm for billet enter stand3:1. Set billet entered stand 3.2. Reset billet left stand 3.

Billet leave stand 3: Executes only when1. Stand 3 should be running2. Stand 3 current should be high and stable3. Billet in stand3 should be in set state.

Algorithm for billet leave stand3:1.From st3 billet time stand 3 billet length is

calculated (ST3_BILLET_LEN) =

(MAX_STAND3_SPEED/MAX_VOLT_LEVEL_COUNT) * STAND3 REFERENCE * ST3_BILLET_TIME/1000

2.Expected stand 7 length is calculated Expected Length at Stand7 = ST3_ST7_REDUCTION *

ST3_BILLET_LEN

3. Cut lengths are calcuted according to the mode selected and are stored in cutpattern register.

Check if stand 7 billet length is greater than minimum billet length (26.0 m), if yes, then

material length= st 7 billet length If no, then material length= nominal billet

length(32m)

If operator selects bar mill mode then operation mode is bar mill (1).

If operator selects sales length mode and auto tail cut is not selected then operation mode is sales length (2).

If operator selects sales length mode and auto tail cut is selected then, Calculate rest length in auto head cut selection using

Calculate rest length without auto head cut selection using

If calculated rest length in the above case is greater than maximum tail length (0.5 m), then operation mode is 3 equal lengths (3) otherwise sales length (2).

If operator selects WRM mode, then add 1 to the count of WRM blooms (only for display) and check the condition.

if MaterialLen < = TotalWRMMateriallen /* 32.7m */

If true then operation mode is WRM (4). Else operationmode is 3 equal lengths (3) and add 1

to the count of over length blooms (only for display). If operator selects bar mill mode and there is some

fault in bar mill or selects3 equal lengths mode then operation mode is 3 equal lengths (3). 3 equal lengths mode is the default mode.

cut pattern is used to store the pattern in which cuts are being given for bar mill mode head length is stored in cut pattern[0], material length in cut pattern[1], tail length in cut pattern[2]. Cut pattern can store 5 different values from cut pattern[0] to cut pattern[4].

Billet enter stand 7: cut pattern pulses are calculated using cut pattern

lengths Calculate cut pattern pulses corresponding to head

length using

Calculate cut pattern pulses corresponding to part lengths (for all parts separately) using

If auto tail cut is selected then calculate cut pattern pulses corresponding to tail length using

Billet leave stand 7:Reset billet entered stand 7. Billet reach PC210:set billet reach PC210.

Billet leave PC210: Calculate actual length of billet at stand 7. Check if If yes calculate new reduction factor

Calculate change in reduction If calculated delta reduction is greater or less

than max delta reduction(0.05) new reduction is again calculated using maxdelta reduction

Average of new reduction and prev st3st7 reduction is taken as new reduction factor.

Signals transferred using Ethernet Global Data from BLM1 to BLM2:

  WRM mode selected information to BLM2 PLC from BLM1 PLC. Head cut for current billet is selected. Tail cut for current billet is selected. Start chop 5m signal. Bar mill selected for the current billet information.  Signals transferred using Ethernet Global Data from

BLM2 to BLM1: Stand 7 current higher than threshold value. Photo Cell 210 signal status. Stand 3 current high and stable. Flying Shear is enabled for cutting. Bit to initiate pulse calculation for shear operation.

BLM2 FUNCTIONS

Main function includes two sub functions:1. Eventdispatchter2. Compute shear speed

Algorithm of event dispatcher: Calculate MR pulses corresponding to 1 sec when PC210 is high and

hence st7 mat speed St7 mat speed= MR CTB* set head cut cali value

Calculate shear reference w.r.t mat speed, for the purpose of feedback using

Calculate shear ref at in mat position with cutting lead

 

BLM2

Billet reach PC210: Initialize cut counter and st7 accum count

reach PC210 to 0. Calculate new shear lead factor based on

operator input

Calculate next cut pulses= st7 accum count reach PC210+ cut pattern pulses

Billet leave PC210: Initialize st7 accum count tail cut extra lead should be 0 and 5 Calculate lead factor corresponding to tail cut

If tail cut is selected

If WRM is selected the billet cannot be more than max WRM length

Compute Shear Speed: ACCELERATE SHEAR: This sub function controls acceleration of shear

from basic position to cut completed position. CUT COMPLETE: Called from accelerate shear

function when cut is completed.1. Reset shear knives entered material.2. Increment cut counter3. Calculate next cut pulses

FUNCTIONS

Calculate shear velocity

Braking control: Calculates shear speed proportional to sqaure

root of diatance to braking positon This includes both braking and position control This function is executed until signal for cut

initiation is available.

THANK YOU