esp32 programming or flashing user programs...

as i was trying to upgrade an old project that had separate wifi-module (esp8266-esp01) and microcontroller(arduino-uno) to improve stability that is brought in by esp32, my first uploading experience was a failure. it reported a fatal error.....blah blah...

i was very much aware esp01 coding needs GPIO-0 GrouNDed (pulled to ground) to make it enter into flashing mode so that new program can be loaded onto it. i had covered this elsewhere. http://tech-steel.blogspot.com/2017/08/prototype-mould-oscillation-checker.html

it was not much hard to identify how to program esp32.
once the coding is complete and compiling is finished and when uploading starts as below....

step 1. press and hold ENable-chip button on ESP-WROOM-32
step 2. press and hold BOOT button
step 3. release EN-button (on this third step we can see the code getting flashed on to esp32-image below.)
step 4. release BOOT button.

dummy bar insertion in a 5 modules caster

this video shows how a solid dummybar in a 5 modules caster is inserted into the mould . there are 2 limit switches and 2 striker-rods and a striker plate to help insert and withdraw dummybar either manually or automatically. these limitswitches help us ensure the physical position of the dummybar while moving. apart from this, actual movement is tracked by rotary encoders that are fixed on motors.

open casting nozzle

in open casting, top nozzle fixed at the tundish wellblock has 22mm dia, while the bottom nozzles can be changed to get desired speed.

bottom nozzles have varying dias like 15.5mm, 17mm, 18mm, 19mm, 20mm and 22mm. first one is always used at the start of casting so that the start of casting is slower, while the largest dia nozzle is used to get the maximum flowrate and hence the maximum casting speed.

pic shows a bottom nozzle that has a dia of 17mm.

we can see the number 7 embosed on the nozzle itself so as to identify the dia of 17mm. 15.5mm dia nozzles will have 5 imprinted while 21mm dia nozzle will have 1 embosed and 19mm dia nozzle will have 9 imprinted.

in the above pic the cream-coloured part at the center that has the bore of 17mm dia is zirconia insert which has a very very good oxidation resistance at high temperatures, strength and erosion resistance. and the gray colored granules that surround the zirconia insert are made of alumina which also has good thermal properties but not as stable as zirconia against erosion.

the pic below shows the surface that will mate with similar surface of top nozzle. this is the surface that normally lies facing upwards while the side shown above normally stays facing mould.

pneumatic valves in a ladle shroud manipulator

this pic above shows a pneumatic valve that is fixed in a ladle shroud manipulator mechanism. arrow marks indicate the direction(downwards) in which the flow is unhindered and the direction (upward) in which flow can be regulated.

next pic shows another valve attached just above this valve but in reversed position. bottom valve regulates the flow into the cylinder (piston side, so that lifting speed of shroud manipulator is proper), while the valve at the top bleeds the Instrument Air from the piston side of the cylinder to lower the manipulator at a controlled speed. while lowering bottom valve does not offer any resistance to the downgoing airflow. the block knob at the side of the valve body helps to regulate the flowrate of the IAir going in or out to help regulate the speed of raising or lowering the manipulator.

LVDT or temposonic or linear sensor

this above pic shows linear variable displacement transducers that are used in tundish slidegate cylinder pistons to track the position of the piston (and hence the position of the rigidly attached slidegate middle plate).

it is these transducers ( temposonic) that give us the feedback about the overlapping of bores of top-middle-bottom slidegate plates of tundish.

the cylinders in which these temposonics are attached have a stroke length of 90mm while the bore dia of slidegate plates is 40mm. this stroke length of more than double the bore-dia ensures perfect safety of slidegate mechanism.

to my limited knowledge, these temposonics work based on magnetostriction method where a moving magnet causes changes in current flow indicating the position of the magnet (in turn that of the piston).

MOM valve damage

mould oscillation is achieved through electro-hydraulic means in modern casters.

in the casters at my present work, these oscillator can have a frequency range of 25-300 CPM (Cycles Per Minute). the total stroke the cylinder piston is 50mm while during normal casting the range required is 8mm to 15mm maximum.

it is an easy logic that the oscillation should start at exact middle of the entire stroke; and target stroke should be distributed equally to the up and down side of this offset position of the cylinder.

it shall further be noted this offset position can be changed but should lie at the right position so that whatever oscillation is achieved should stay in line with the radius of the machine. this is necessary to avoid any external stress that may be exerted on the tender, weak shell inside the mould that may easily rupture.

these pics show a damaged valve stand that drives the cylinder up and down.

the first pic shows the LVDT placed inside the actuator piston of the hydraulic cylinder on top portion of the entire mechanism in the top of the image. the hoses below carry mould (inlet&outlet) and spray water of zone-1. the bob like structure positioned at an angle in the mechanism is an oil accumulator that helps in fast response to compensate  for pressure drop inside valve or cylinder.

in the following image, cable that is from the LVDT (temposonic) is shown inside that round protection housing. the other two blocks of the mechanism just below that round housing show the actual valve (middleblock) and below that lies the moog controller block.

following closer image shows the same, but one can easily see the damaged valve block. this damaged was caused by excessive insertion of bottom-fed-dummybar. it travelled excessively up into the mould because of tracking failure from slipping withdrawal module motor-roll. the tracking is done using a rotary encoder attached to the motor.

it can be seen from the pics, the valve block has damaged along the ON-OFF valve connector on the left side while the right side ON-OFF valve stays intact. just above them at the middle lies one of the two pressure gauges that track the pressure built on the top side of the cylinder during oscillation. moog block makes this entire setup a SERVO VALVE whereby error tracking and correction in input command to the valve spool is done through inbuilt electronic circuitry to ensure the desired positions are achieved.

centering of SES

during casting, it is important to have the body-centre-line of the SES aligns with the body-centre-line of the mould. if this alignment is not ensured and the SES stays close to one of the four sides of the mould, then it is likely to discharge fresh metal much closure to that side of the mould.

closer position of the discharge point of SES takes a longer distance to develop the necessary shell-thickness to develop sufficient shell thickness, thereby sufficient strength to withstand the ferrostatic pressure of the liquid steel above it at any given point of the strand from meniscus.

closer side may have thinner than normal shell thickness while the far side may have thicker than normal thickness. thinner shell may not strong enough to withstand ferrostatic pressure and thicker shell may develop extra strain, thereby chances for breakout are enhanced due to misalignment.

this pic above shows an improperly aligned SES in mould during casting. it becomes the responsibility of the mould operator to correct it by CT movement of tundish which is done through hydraulic cylinders in tundish cars.

SES clean and choked

these pics show the SESs (Sub Entry Shrouds) of the same tundish, photographed immediately after end of casting from adjacent strands.

if we take a look at these 2 tundish shrouds, the easily distinguishable feature is the deposition at the bottom end of the shroud on the first pic.

not something strange to steel making, that is a mass of inclusions( most likely alumina, silica, MnO, CaO and other complex oxides).

with this level of depositions, that particular strand got chocked during casting unexpectedly which is undesirable for a planned smooth casting. unplanned closures of strands, and in turn machines in somecases, may upset the dynamics of the shopfloor.

this is evident when 1 strand is getting smoothly cast, another strand of the same tundish may develop a lof of inclusion buildup which eventually may choke that strand.

the reason for buildup in one strand could be air-ingression through the seating area of the SES; likely, it is combined with a sufficient supply of inclusions from the steel.

in any case, one of the important responsibilities of LF is to prepare heats with least amount of inclusions before sending heats to caster. it is not just the ingression of air that could build up that much of inclusions to choke SES without the indigenous inclusions from secondary metallurgy units.

casting personnel has little to no control over inclusions of steel. the pic above speaks about the critical responsibility that lies with the LF personnel.

further more, the mild red color of SES in the second pic indicates this tundish was just taken out of casting hence the SES is still red hot; the SES in first pic is cold and black that indicates that strand has been closed much earlier.

lollipop

these are the two types of lollipop samples presently we are taking at our shopfloor for tundish sampling.

the second type was brought in to take samples where there tundish temperature is below 1500degC for high carbon grades. hight carbon grades at our shopfloor can hit as high as 0.8 % (wt) C in liquid steel. the liquidous temperature of that steel goes down to around 1465 typically while some grades like 1008 have a liquidous of around 1525degC. the range is easily around 60degC.

extensively used top sampler does not give us properly filled and sized samples for high C grades at lower temperature in tundish. hence the second was introduced. still, the bottom samplers pose a different challenge at the lab because the robot there is not designed to handle that smaller sized sample. :-)

a ladle.....

there it is.

just after deslagging, ready to go back to ladle preparation bay for lining, purging plugs, tapping nozzles and slidegate plates checking.

the rings show the working lining of a ladle and the top freeboard and slaglining too.

since basic slags are made at LF in this plant, this inner lining is made of basic bricks so that the attack of basic slag on the lining will be minimal and least aggressive.

what makes the basic bricks basic?

well, when we take a look at the extended basicity formula ( CaO+MgO+MnO) / (SiO2+Al2O3+FeO), it can be easily understood the molecules of the numerator contribute to basic nature while those from the denominator make the refractories acidic.

so it can be inferred, the ladle inner working lining should be made of mainly one or more of the molecules from the numerator to make it basic.

ladle and tundish inner, working linings are made of MgO bricks while the backup linings are made of Al2O3  bricks.

bricks at the bottom, metal-lining generally give a life of around 120-150 heats while the slag lining bricks are debricked and relined after half of that number.

once a ladle is put into service, slag-lining brickes are changed twice in a campaign while metal-lining bricks are changed once in that life of around 120-150 heats. after completion of that campaign, entire working lining (bricks of slag as well as metal lining) is stripped off and relined after sufficient inspection or patching as necessary.

purging plugs give a life of around 30 heats while the slidegate plates hardly give 4 heats life. outer nozzles also get changed along with the bottom plates while inner nozzles give a life of 5 or 6 heats in general. but everything is subjected to REAL TIME, ACTUAL condition of the ladle; best is, NOT TO GIVE TAKE ANY CHANCE when there is even a little doubt, since anything untoward may cost huge losses than changing the doubtful, suspected part of the ladle.

tundish starter tube.

in tundishes with slidegate mechanisms, starter tubes are used to initiate filling of mould during start of casting.

these starter tubes are fixed above the wellblock of tundish, and they have a slot positioned somewhere around 350 to 450 mm above the tundish inner floor. this helps to start flow into mould at various tundish metal levels at various times one by one.

they normally float to the top after few minutes of start of casting.

pic below shows the starter tube when the tundish is ready to take heat after preheating.

draining off of ladle slag from tundish

we, machine incharges of casting floor, have damaged the cables of ladle-slag detectors as they hang down from ladles during rotation. manual errors have damaged them repeatedly, so these cables were not restored anymore.

the responsibility then fell on the machine-in-charges to detect and stop ladle slag from entering into tundish. manual and visual observation is bound to have errors, and in such cases accumulation of heavy ladle slag in tundish have a lot of adverse effects on casting.

tundish steels gets excessively oxidized, crust formation on top of tundish obstruct sample collection and manual temperature measurements can be a lot misleading.

automated monoblock stoppers may get jammed due to heavy slag around them leading to heavy torque and failure of actuators.

excessively oxidized steel can erode tundish slidegate plates or monoblock stopper tips leading to running of strands.

during such times it becomes an absolute necessity to drain the slag through the overflow spout into the emergency containers provided there is enough space for it.

pic below shows one such incident where slag is drained off tundish. it must be noted, steel should not be drained along with slag as this is a heavy loss.

from the pic one must be able to understand how slag (with glass formers like Silica and alumina) form a continuous thread while flowing down the spout WITHOUT BREAKING OR SPLITTING OFF as soon as flowing out.

this slag thread slowly draining off the spout explains a lot, about the high viscosity (around 10times that of liquid steel), that results from interlinking of CaO, silica, alumina and other network forming, slag making molecules that does not allow splitting or breaking off of streams (which normally  happens when liquid steel flows.) one can easily identify what overflows is metal or slag with this simple idea in mind.

fly link for tundish change

we do a lot of tundish changes to continue casting uninterrupted even after the life of one tundish is reached, replacing the old tundish with a new one; this process is also called fly tundish.

following pics show the fly link used to form a physical link between old and new billets during tundish change.

these links are designed to link sq.150 size billets in mould.