COMPLETE SPECIFICATION RELATING TO INVENTION
TITLE OF THE INVENTION
AN IMPROVED, CONTINUOUS COATING LINE AND A PROCESS OF CONTINUOUSLY COATING METAL STRIP

A. I

NVENTION:

METHOD AND EMPLOYMENT OF APPARATUS TO USE WITH A HEATING DEVICE
5 SPECIFICALLY NEAR INFRA RED OVEN OR UV OVEN OR A COMBINATION OF BOTH EMPLOYED HORIZONTALLY WITH STRIP PASSING THROUGH THE HOT CURING OVEN HORIZONTALLY FOR PRODUCTION OF HIGH QUALITY COLOUR COATED PRODUCT ON A
VARIETY OF SUBSTRATES, SUCH AS, PLAIN COLD ROLLED STEEL, COLD ROLLED
STEEL WITH ONE SIDE OR BOTH SIDES COATING OF ZINC OR ZINC-ALUMINIUM ALLOY
10 OR SO-CALLED GALVANNEAL ALLOY COATING OR ZlNC-RICH PRIMER COATING,
STAINLESS STEEL STRIP OR ALUMINIUM/ ALUMINIUM ALLOY STRIP IN A CONTINUOUS FASHION ON A CONTINUOUS COLOUR COATING LINE FOR BOTH PRIMER AND FINISH COATING IN A SINGLE OPERATION EMPLOYING MULTI-COATING COATING HEADS OR SINGLE OR IN ANY MANNER WHATSOEVER APPLYING SOLVENT-BASED OR WATERBORNE
15 PAINTS WITH ADDITIVES IN THICKNESS RANGING FROM 3 (THREE) MICRONS TO 400 (FOUR HUNDRED) MICRONS PER SIDE OF STRIP AND WITHOUT ANY LIMITATION ON STRIP
THICKNESS AND WIDTH OF SUBSTRATE AND WITHOUT LIMITATION IN THE RANGE OF APPLICATION OF ORGANIC AND INORGANIC COATINGS OF GRADES/ COLOURS/ VISCOSITIES.
20

B.

METHOD AND APPARATUS OF THE INVENTION:

(I) THE INVENTION RELATES TO A METHOD & APPARATUS FOR CONTINUALLY
25 PRODUCING COLOUR COATED COILS AT VERY HIGH SPEEDS WITH HORIZONTAL
NEAR INFRA RED HEATING OVENS OR SUCH FAST CURING DEVICES
SPECIFICALLY USED FOR CURING OF SOLVENT-BASED PAINTS TO ACHIEVE
SHORTEST CURING TIME OF ORGANIC AND INORGANIC COATINGS INCLUDING
WATERBORNE COATINGS IN TWO TO THREE SECONDS OR IN THE RANGE OF 1
30 SECOND TO 14 SECONDS MAXIMUM.
(II) MORE SPECIFICALLY, THE METHOD EMPLOYS OPTIMUM HORIZONTALITY OF STRIP
PATH THROUGH THE OVENS BY HIGH TENSION BRIDLES PLACED AND POWERED
AT ENTRY & EXIT OF EACH OVEN IN SUCH A MANNER THAT THE STRIP SAG
35 ENCOUNTERED IS KEPT WITHIN THE LOWEST LIMITS OF RANGE PERMISSIBLE IN
SUCH OVENS FOR UNIFORM HEATING OF STRIP SURFACE BOTH SIDES FROM THE
SENSITIVE RADIATION SOURCE WITHIN THE PRESCRIBED SHORT RESIDUAL TIME IN THE OVEN OF A PRACTICAL RANGE OF 1.5 SECONDS TO 3 SECONDS WITH STRIP SUPPORT SPAN OF AROUND 20 METERS TO 30 METERS BUT NOT LIMITING
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TO THIS RANGE. IN OTHER WORDS, WITHIN THE LIMITS OF COATING CACACITY OF MACHINERY FOR HIGH SPEED COLOUR COATING WITH THE OVEN LENGTH THE UNSUPPORTED STRIP LENGTH GENERALLY IS EXPECTED TO FALL IN THIS RANGE.
5 (III) IT IS ALSO ANOTHER OBJECT OF INENTION TO MOUNT THE HEATING DEVICES ON MECHANICAL GADGETS INVOLVING HORIZONTALLY ACTIVATED WEDGE PASS LINE ADJUSTMENT WITH HYDRAULIC/ PNUMATIC OR ELECTRICAL ACTUATORS WITH POSITION TRANSDUCERS TO TILT THE OVEN FROM ENTRY TO EXIT BY A FRACTIONS OF DEGREES AND MINUTES AND VICE-VERSA OR TILT THE OVENS
10 FROM OPERATING TO DRIVE SIDE OR DRIVE TO OPERATING SIDE BY THE MOUNTED GADGETS AND TRANSDUCERS OF COMPLETE OVEN ADJUSTMENTS IN
X, Y, Z AXIS WITH READ OUT WHICH CAN BE AUTOMATED TO POSITION THE HEATING DEVICE WITH SIGNALS TO ENABLE THE OPERATOR TO ADJUST THE OVEN CONFIGURATION FOR OPTIMUM UNIFORMITY OF HEATING OF SURFACE OF PAINT
15 COATED STRIP TO PRODUCE THE BEST QUALITY OF CURED, COATED STRIP SURFACE COATING TO THE QUALITY STANDARDS OF INDUSTRIAL PRACTICE.

(IV) IT IS YET ANOTHER OBJECT OF THE INVENTION THAT THE HIGH TENSION DEPLOYED IN THE STRIP DYNAMICS PROMOTES THE UNIQUE CONDITION THAT THE
20 PRESSURES ON THE APPLICATOR ROLL TO THE STRIP AT TURNOVER DRUM AND THE PRESSURE OF PICK UP ROLL TO APPLICATOR ROLL ARE SUBSTANTIALLY LOWER AND PRACTICAL NORMAL PRESSURE NEEDS ONLY TO BE APPLIED
WITHOUT ANY ADVERSE EFFECTS OF VISCOSITY, PAINT TEMPERATURE OF PAN, COATING ROLL WEAR, COATING ROLL TEMPERATURE ETC. AND WEAR OF
25 ROTATING PARTS AND ROLL COVERING ETC. NORMALLY ENCOUNTERED WITH HIGH PRESSURE APPLICATIONS. IN FACT THE HIGH STRIP TENSION USED HAVE SUCH AN EFFECT THAT PAINT APPLICATIONS BECOME A SIMPLE OPERATION NEEDING NO HIGH PRESSURE COATING ROLL APPLICATION.
30 (IV) IT IS YET ANOTHER OBJECT OF THE INVENTION TO UTILISE A VARIETY OF SOLVENT THINNER OF VARIOUS PROPORTIONS ON THE NIR SUITED PRIMER PAINT AND FINISHER PAINT TO BE COATED WHICH SMOOTHENS THE COATING UNIFORMITY PREVENTING SURFACE ROUGHNESS THE FORMATION OF CRATERS OR BUBBLE TO
35 PREVENT ANY POP UP OF COATING WHILE FACING THE HIGH POWERED RADIATION HEATING SOURCE DURING CURING AT THE SHORTEST RESIDUAL TIME.
(IV) IT IS YET ANOTHER OBJECT OF INVENTION THAT WITH THE METHOD AND USAGE OF APPARATUS DESCRIBED THE CONVENTIONAL LONG HORIZONTAL VESTIBULE
40 NEEDED FOR WET PAINT FLOW OUT TIME OF AT LEAST 3 TO 5 SECONDS USED IN PRACTICE IN THE ART OF COLOUR COATING BEFORE THE STRIP ENTERS THE CURING OVEN IS ELIMINATED I.E., EMPLOYING A LONG VESTIBULE LENGTH OF 5
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METERS TO 15 METERS BEFORE THE OVEN ENTRY OF COATED STRIP IS NOT NECESSARY THUS SAVING BUILDING LENGTH EXCEPT A SHORT VESTIBULE COVERING SAFETY AND GUIDED AIR INTAKE OPENING NEEDED FOR PROCESS
REQUIREMENT AND SAFETY IS ALL THAT IS REQUIRED. 5
5 C. BACKGROUND OF INVENTION: (I) PREAMBLE:
METHOD AND EMPLOYMENT OF APPARATUS OF NEAR INFRA RED OVEN OR UV
10 OVEN OR A COMBINATION OF BOTH EMPLOYED AT HORIZONTALLY FOR PRODUCTION OF
HIGH DUALITY COLOUR COATED PRODUCT ON A VARETY OF SUBSTRATES, SUCH AS,
PLAIN COLD ROLLED STEEL, COLD ROLLED STEEL WITH ONE SIDE OR BOTH SIDES
COATING OF ZINC OR ZINC-ALUMINIUM ALLOY OR SO-CALLED GALVANNEAL ALLOY
COATING OR ZINC-RICH PRIMER COATING, STAINLESS STEEL STRIP OR ALUMINIUM/
15 ALUMINIUM ALLOY STRIP ON A CONTINUOUS COLOUR COATING LINE FOR BOTH
PRIMER AND FINISH COATING IN A SINGLE OPERATION EMPLOYING MULTI-COATING
COATING HEADS OR SINGLE OR IN ANY MANNER WHATSOEVER APPLYING SOLVENT-
BASED OR WATERBORNE PAINTS IN THICKNESS RANGING FROM 3 (THREE) MICRONS TO
200 (TWO HUNDRED) MICRONS PER SIDE OF STRIP AND WITHOUT ANY LIMITATION ON
20 STRIP THICKNESS AND WIDTH OF SUBSTRATE AND WITHOUT LIMITATION IN THE RANGE
OF ORGANIC AND INORGANIC COATINGS.
(II) PREVIOUS ART OF COATING:
25
o CONTINUOUS CURING OVENS FOR COIL COATING INDUSTRY, PER SE, ARE VERY
OLD IN THE ART.
o THE MOST COMMON CONTINUOUS PAINT COATED STRIP CURING OVEN USING
30 CONVENTIONAL HEAT TRANSFER MEDIA FOR CURING THE COATING TO ITS PEAK
METAL TEMPERATURE IS OF HORIZONTAL CONFIGURATION WITH STRIP TRAVEL
PATH AS A TYPICAL CATENARY WITH HOT OVEN AIR DIRECTED AGAINST THE
STRIP THROUGH PLENUMS ABOVE AND BELOW THE STRIP. THE CATENARY PATH
OF TRAVEL IS MAWTAINED BY A SPECIFIC TENSION VERY TYPICALLY OF 2.5
35 KG/MM2 OF STRIP CROSS SECTION (FLG. 1). LOW POINT OF CATENARY IS
MAINTAINED BY LOOP CONTROL SENSORS TYPICALLY OF THE STATE OF ART. OVENTEMPERATURES ARE MAINTAINED TYPICALLY AT 420°C TO SUPPORT THE
HEATING OF METALLIC STRIP THROUGHPUT THROUGH FURNACE BY EMPLOYING OVEN ZONE BURNERS AS METHOD OF CURING OF COATING BY HEAT FLOW INSIDE
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OUT OF THE STRIP AND HIGHER OVEN TEMPERATURES NEEDED FOR CONVECTIONAL HEAT TRANSFER WHICH IS SOMEWHAT SLUGGISH AND TYPICALLY EMPLOYING AN OVEN INCINERATION SYSTEM FOR RECOVERING THE ENERGY FOR
5 OVEN HEATING BY DESTRUCTION OF PAINT SOLVENTS BY THERMAL OXIDISATION AND UTILISING THE PRODUCT FOR OVEN HEATING NEEDS EITHER THROUGH HEAT EXCHANGERS DIRECTING HEATED FRESH AIR INTO OVENS OR BY DIRECT INJECTION OF FUMES INTO OVEN CIRCULATION SYSTEM.
o AGAIN THE HORIZONTAL CONVENTIONAL CURING OVEN AS A FLOTATION OVEN
ALSO EMPLOYED WHERE HIGH POWERED OVEN RE-CIRCULATION FAN SUPPORTS THE STRIP IN NEAR HORIZONTAL FASHION BY THE PRESSURE OF HOT AIR ABOVE AND BELOW THE STRIP IN A CONTROLLED FASHION AND CURING OF COATING PROCEEDS THROUGH THE LINE OF TRAVEL OF STRIP THROUGH OVEN SIMILAR TO THE CATENARY OVEN. (FIG.2)
o IT IS TO BE POINTED OUT THAT CONVENTIONAL HORIZONTAL OVENS ARE
POSITIONED IN SUCH A WAY FOR THE WET PAINT ON COATED STRIP FLOW OUT TO STABILISE BEFORE ENTERING THE OVEN EMPLOYS A VESTIBULE RANGING FROM 4 METERS IN LENGTH FOR LOW AND MEDIUM STRIP SPEEDS OF 78-100 METERS PER MINUTE INCREASING UP TO 12 METERS IN LENGTH OR HIGHER FOR HIGH SPEED LINES IN EXCESS OF 100-200 METERS PER MINUTE SPEED RANGE.
O ALL THESE OVENS TYPICALLY ARE EMPLOYED WITH PAINTS FOR INDUSTRIAL CURING FINISHES AT 22 TO 24 SECONDS (FURNACE RESIDUAL TIME) CURING TIME TO ATTAIN A TYPICALLY PEAK METAL TEMPERATURE OF 230°C FOR ATTAINING THE QUALITY LEVELS EXPECTED IN TERMS OF BEND, CUPPING TEST,
MEK RUBS, HARDNESS, GLOSS LEVELS, COATING DRY FILM THICKNESS DEVOID OF OTHER SURFACE QUALITY DEFECTS, SUCH AS, EDGE BLISTERS, ROUGHNESS OF SURFACE, PAINT LINE MARKS ETC. THE INSIDE OVEN ATMOSPHERE HAS TO BE MAINTAINED TYPICALLY AT ABOUT 400°C TO 420°C.
NEW GENERATION CURING OVENS:
O FOR HIGHER SPEEDS FOR MORE PRODUCTION NEEDS USAGE OF CATENARY OVENS WITH LARGE STRIP SAG AND OVEN LENGTH SPANNING OF 60 METERS HAVE BECOME TOO UNWIELDLY BOTH IN TERMS OF HUGE SPACE OCCUPATION AND CUMBERSOME OVEN CONSTRUCTION. THE SAG AT OVENS WARRANT LRGE BUILDING HEIGHTS DEEP FOUNDATION AND LARGE VOLUME OF SUPPORTING TECHNOLOGICAL STRUCTURE.
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o WITH THE DEVELOPMENT OF COMPETING TECHNOLOGES, OTHER TYPES OF OVENS, BASICALLY ELECTRIC OPERATED, SUCH AS INDUCTION HEATING PRINCIPLE, INFRA RED HEATING TECHNIQUE, INFRA RED RADIATION TYPE HAVE
5 EMERGED IN THE LAST FEW YEARS WITH SHORT OVENS, SHORT CURING TIMES.
ALL THE NEWLY DEVELOPED OVENS HAVE THE SINGLE OBJECTIVE AS FOLLOWS:
TO CREATE AN INSTANTANEOUS AND MORE EFFECTIVE HEATING
10 TECHNIQUE FOCUSSING THE HEAT TO CURE THE COATING
PREDOMINANTLY, RATHER THAN HEATING BASE STEEL SUBSTRATE OF
THE TOTAL THROUGHPUT OF STRIP, I.E., BY THE RADIATION HEAT WAVES
PENETRATING THE COATING TO CURE THE COATING FAST WITH MINIMUM
ENERGY TO HEAT STEEL SURFACE SO THAT COATING CURES FAST BY HEAT
15 FLOW OUTSIDEHN, THUS REACHING QUICK CURING EFFECT BESIDES THE
ADVANTAGE THAT WATER QUENCHING TO BE FOLLOWED AFTER THE OVEN BRINGS LESS STEEL HEAT INTO THE WATER CIRCUIT THEREBY COOLING EFFICIENCY IS MORE CONSISTENT WITH LESS RISE OF COOLING WATER TEMPERATURES WHICH OF COURSE IS NOT THE OBJECT OF THE PRESENT
20 INVENTION.
ALL OF RAPID CURING TECHNIQUE EMPLOYED BY THE NEW GENERATION
OVENS IS TO CURE THE COATING BY HEAT, SUCH AS RAPID INDUCTION
HEATING DIRECTING THE ELECTRIC HEATING FLUX PATH TO THE SURFACE
25 OF STRIP FOR QUICK HEATING OF COATING AND CURING OF THE SOLVENT
PAINT.
INFRA RED SOURCE BY WELL DESIGNED HEAT SOURCE DIRECTING THE
HEAT WAVES ONTO THE SURFACE OF COATING BY EMPLOYING SHORT
30 WAVE RADIATION IN THE RANGE OF 1.2 TO 2.0 MICROMETER NEEDING
CURING TIME OF 15 TO 18 SECONDS RANGE FOR COIL COATING APPLICATIONS IN THE RANGE OF DRY COATING FILM THICKNESS RANGES OF 12 MICRON TO 20 MICRON.
35 NEAR INFRA RED HEATING SOURCE, WHICH EMPLOYS FURTHER SHORTER
WAVES RANGE FROM 0.38 TO 1.38 MICROMETER WITH A CURING TIME OF 1.5 TO 3.0 SECONDS FOR THE COIL COATING ON CONTINUOUS STRIP LINES WITH THE DRY FILM THICKNESS OF 12 MICRON TO 20 MICRON.
40 BUT AS ON DATE, MOST OF THESE OVENS HAVE BEEN EMPLOYED IN A VERTICAL FASHION IN A SMALL SCALE FOR CURING CONVERSION CHEMICAL COATINGS, PASSIVATION DRYING, ANTHTNGER PRINT CURING ETC. RECENTLY A LARGER VERSION OF A VERTICAL INFRA
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RED OVEN HAS BEEN REPORTED TO BE INSTALLED IN THE EXIT SECTION OF A HIGH SPEED GALVANISING UNE WITH VERTICAL PAINT COATING HEADS BEFORE THE OVEN ON EITHER SIDE OF THE STRIP WITH COATERS MAINTAINED AT 12 TO 15 METERS DISTANCE FROM THE VERTICAL OVEN ENTRY. SIMILARLY INDUCTION HEATING APPARATUS HAS BEEN INSTALLED
5 IN A VERTICAL FASHION IN SOME PARTS OF THE WORLD.
(IV) CONCEPT OF NEAR INFRARED OVEN:
10 BUT, NEVER HAS BEEN FULL SCALE NEAR INFRA RED OVENS INSTALLED FOR CONTINUOUS HIGH SPEEDS IN A HORIZONTAL FASHION AS SUCH A CONFIGURATION WAS BELIEVED TO HAVE DELETERIOUS SAGGING EFFECT ON THE STRIP DYNAMICS WHICH COULD CREATE IMMENSE CURING PROBLEMS FOR WIDE RANGING STRIP SIZES WHOSE CROSS SECTIONAL AREA AND THE CORRESPONDING WEIGHT THEREOF COULD RESULT IN
15 VARIOUS SAGGING CONDITIONS. IT IS ALSO A KNOWN FACT THAT RUNNING AT TOP SPEEDS WITH CURING TIME IN OVEN OF AS LOW AS 1.5 TO 3.0 SECONDS POSES AN EXTREMELY SENSITIVE ENVIRONMENT DEPENDING ON VARIOUS FACTORS OF PAINT SHADES, VISCOSITY, WET FILM THICKNESS, APPLICATOR ROLL COVERING MATERIAL DURABILITY AND APPLICATOR/ PICK UP ROLL PRESSURES TO BE USED AND HEAT REFLECTIVITY/
20 RADIATION HEAT SOURCE JUDICIOUS CONTROL ETC.
(V) VERITCAL NEAR INFRARED/
25 INFRA RED CURING OVEN:
THERE ARE PRACTICES IN INSTALLING INFRA RED AND NEAR INFRA RED OVENS
VERTICALLY WITH STRIP PASS UNE PASSING VERTICALLY THROUGH THE ABOVE
HEATING APPARATUS, WITH SUCH CONFIGURATION MORE IN NUMBER FOR VERTICAL
30 CHEMICAL CONVERSION COATINGS WITH ESSENTIALLY WATER BORNE COATINGS OF
SMALLER RANGE DRY FILM THICKNESS OF 3 TO 5 MICRONS WITH PEAK METAL
TEMPERATURES OF 120° C RANGE GENERALLY OR SOLVENT BASED COATINGS FOR
AUTOMOTIVE APPLICATIONS IN A PMT RANGE OF 170°C TO 210°C WITH BRAND
NAMES FOR EXAMPLE GRANACOAT, BONA ZINC ETC. THESE HEATING
36 APPARATUS VARY IN LENGTH OF 3 METERS TO 6-7 METERS DEPENDING ON LINE
SPEEDS AND THICKNESS RANGES OF STRIP.
BUT SUCH A HEATING APPARATUS INSTALLED FOR A FULL FLEDGE PRIMER AND
FINISHER COATING CURING APPLICATION FOR MEDIUM OR UGH STRIP SPEEDS WITH
40 SOLVENTS WILL BE APPRECIATED, WILL CALL FOR LARGER LENGTH
IN THEJ STATE OF ART M COLOUR COATING, IT IS WELL KNOWN THAT AFTER CURING OF
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THE WET PAINT AFTER COATING STRIP SUBSEQUENTLY WILL HAVE TO PASS THROUGH SUCH PROCESSING STEPS AS AIR QUENCHING OF THE STRIP FROM ITS PEAK METAL TEMPERATURE OF AROUND 200°C - 240°C TO 150°C - 180°C AND THEN WATER QUENCH IN DEMORALISED WATER TO AROUND 50°C AND FURTHER DRY IT BY A VARIETY OF DRIERS SUCH AS AIR KNIFE BLOW OR HOT AIR DRIER EMPLOYED BOTH OR INDIVIDUALLY BESIDES MECHANICAL DEVICES TO ABSORB ANY WET FILM DUE TO EXCESSIVE DRAG OUT OF WATER CARRY OVER FROM WATER QUENCH TANK FOR STITCH PASS THROUGH ETC.
10
(VI) DISADVANTAGES OF VERTICAL INFRA RED / NEAR INFRA RED
OVENS:
THE ATTENDANT DISADVANTAGES WITH HEATING APPARATUS AND THE ASSOCIATED
15 EQUIPMENT WHICH HAVE TO FOLLOW WHEN CONFIGURED IN A VERTICAL FASHION AS IT
SHOULD BE SINCE THE FIRST TOUCH POINT OF CURED STRIP EXITING FROM THE CURING
OVEN IS THE WATER COOLED ROLL AT THE ENTRY POINT TO SUBSEQUENT WATER
QUENCH TANK ARE QUITE OBVIOUS AS FOLLOWS:
20 (l) HEIGHT OF THE BUILDING HOUSING THE EQUIPMENT IS QUITE SUBSTANTIAL.
(ii) ACCESS TO INDIVIDUAL SECTION OF PROCESS CONTROL AT DIFFERENT
ELEVATIONS ARE VERY DIFFICULT TO MONITOR AND MAINTAIN.
25 (iii) VERTICAL ELEVATOR NEEDED AT DIFFERENT LANDING LEVELS OF THE SET-UP.
(iv) HEATING BRIDGES OF INFRARED / NEAR INFRARED CURING OVEN HAVE TO BE
INSPECTED WITH THE HELP OF ELEVATORS OFTEN FOR TRIPPING OR LAMP
30 FAILURE OR LAMP REPLACEMENTS.
(v) THE CONTINUOUS MONITORING OF EMITTER REFLECTOR ASSEMBLIES,
REFLECTOR SHIELDS QUARTZ GLASS AND THEIR REPLACEMENTS AND EMITTER
WATER COOLED CHAMBERS WITH OVER-TEMPERATURE SENSORS ARE QUITE
35 CUMBERSOME.
OVER AND ABOVE THE PHYSICAL DISADVANTAGES CITED ABOVE, THERE ARE
ALSO TECHNICAL AND TECHNOLOGICAL DISADVANTAGES.
40 (vi) FOR INSTANCE, IT IS KNOWN m THE ART OF COATING THAT A CONSIDERABLE DISTANCE OF WET COATED STRF IS MAINTAINED FOR THE PAINT TO FLOW OUT
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EVENLY BEFORE IT ENTERS THE OVEN FOR CURING. THERE COULD BE MANY
REASONS FOR THIS. FOR EXAMPLE THE STRIP WITH A STANDARD SPECIFIC
TENSION OF 2.5 KG/MM2 SECTIONAL AREA ON HORIZONTAL OVENS OR VERTICAL
OVENS WITH SLIGHTLY HIGHER VALUES OR LOWER VALUES WHEN WRAPPED
5 AROUND THE TURN OVER DRUM WHERE THE APPLICATOR ROLL IS EMPLOYED IN A
POPULAR REVERSE COATING APPLICATION, THE DYNAMICS OF COATING FILM THICKNESS IN WET CONDITION AND IN VARYING SPEEDS ESPECIALLY IN HIGHER COATING SPEEDS POSE VARYING PARAMETERS TO BE CONTROLLED SUCH AS:
10 o MORE PAINT PUMPING EFFECTS ON STRIP.
O PRESSURE APPLICATION ON APPLICATOR ROLLS TO MAINTAIN WET FILM THICKNESS.
o AGAIN THE COMPLICACY OF VARYING VISCOSITY OF PAINTS ENCOUNTERED WILL
HAVE AN ADDITIONALLY IMPOSED REQUIREMENT ON INCREASED OR VARYING
15 COATING ROLL PRESSURE TO BE MEASURED AND ADJUSTED INTERMITTENTLY.
O INCREASED PRESSURE ON APPLICATION ROLLS RESULTS IN A CONTINUAL INCREASE IN TEMPERATURE OF THE ROLL BARREL AND THE PAINT ITSELF IN THE COATING PAN WHICH CAN REACH AROUND 80°C TO 90°C. 20
o INCREASED TEMPERATURE OF ROLL HAS A MUCH SHORTER LFE ON ROLL COVERING NEEDING QUICK REPLACEMENT AND INCREASED HIGHER TEMPERATURE RESULTS IN VARYING VISCOSITY WHICH ONCE AGAIN GENERATE THE COMPLEXITY OF CONTINUOUS COATING OPERATING PARAMETERS.
25
O IN ANY CASE THE LENGTH OF THE INLET VESTIBULE IS CONFIGURED FOR THE STABILISATION OF THE WET FILM ALLOWING IT TO FLOW OUT AND SETTLE IN A 3 TO 4 SECONDS HOLD TIME BEFORE CURING.
30 o THE EFFECT OF SUCH A WET PAINT FLOW OUT IN AN ENTRY VERTICAL VESTIBULE
IS EASY FOR ANY ONE TO COGNIZE THE FACT THAT THE WET FILM OF PAINT FLOW BY GRAVITY ESPECIALLY ON THICKER COATING AND THINNER COATING WITH MORE PERCENTAGE THINNER SUCH AS 40% SOLID CONSTITUENTS OF PRIMER OR FINISHER COULD FORM TEAR-SMEAR SORT OF EFFECT OR SMILING FLOW
35 LINES IN THE SPEED RANGE OF COATINGS WITH A NUMBER OF VARYING
PARAMETERS CITED ABOVE INCLUDING INCOMING STRIP ROUGHNESS, RA VALUES WHICH MAY VARY ACROSS THE STRIP WIDTH AFFECTING VARYING WET FILM THICKNESS AFFECTING THE FINISHED PRODUCT SURFACE QUALITY DURING SUBSEQUENT CURING.
40
(VII) ADDED TECHNICAL DISADVANTAGE IS OF COURSE THE ADDITIONAL MACHINERY NEEDED FOR THE STRIP PASS LINE DEFLECTIONS FOR APPLYING FINISH COAT ON
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THE PRIMER COATED SURFACE AND THE BACK COAT APPLICATION WITH T-
COATER SYSTEM WHEN EMPLOYED.
(VIII) ADDITIONALLY, OPTIMUM OVEN LOADING COULD BE DISTURBED WHEN COATING IS
5 TO BE APPLIED IN A PASS CONFIGURATION WHICH HAS TO EMPLOY POSSIBLY TWO
Y COATERS AND AN S-TYPE PRIME COATER WITH BACK COATING, I.E., PRIMER &
BACK COAT THROUGH THE PRIME OVEN AND FINISH COAT ON ONE SIDE IN THE
FINISHING OVEN.
10 (IX) ON THE OTHER HAND EMPLOYING VERTICAL COATERS HAVE ALL THE RISKY
FACTORS OUTLINED ABOVE BESIDES THE MOST DIFFICULT OPERATION OF EMPLOYING HIGH COATING OFFSET ROLL PRESSURES ON FRONT AND BACKSIDES OF THE STRIP.
15 (X)
FURTHER IT IS OBVIOUS THAT A VERTICAL WATER QUENCH AFTER CURING IS VERY
DIFFICULT TO EMPLOY AND WARRANTS EXPENSIVE GADGETS ON TOP OF ANY
CONTACT ROLL (PREFERABLY WATER COOLED) OR REFLECTING THE STRIP TO HORIZONTAL WATER QUENCH TANK WHICH IF OR WHEN EMPLOYED COULD RESULT
IN A CRACKED COATING SURFACE LEADING TO REJECTS AS THE DEFLECTION ON FRESHLY PANTED STRIP IS DONE AFTER WATER QUENCH AT AROUND 50°C OF STRIP TEMPERATURE.
EMPLOYING WATER QUENCH AT SUCH HIGH LEVELS NOT ONLY NEEDS WATER
BOOSTER PUMPS BUT WATER LEAKAGES FROM THE HEIGHT COULD HAVE
25 DETRIMENTAL EFFECTS ON SHOP FLOOR AND OTHER AUXILIARY EQUIPMENT.
(XI) SIMILARLY, VERTICAL PASS LINES NEED STEERING CONTROLS AT ITS LOCATION IN
HIGH BAY WHICH NEED HYDRAULIC EQUIPMENT MOUNTED AT THIS LEVEL WHICH IS
TO BE MAINTAINED AND MONITORED WITH SERVICE ELEVATOR WITH CAMERA/
30 FLASH BACK OF STRIP POSITION ON DEFLECTOR ROLLS.
(XII) STEERING CONTROLS AT LOWER TENSION VALUES NORMALLY EMPLOYED TO
STEER THE STRIP WANDER WHICH COULD POSE PROBLEM WHEN HEATING
BRIDGES ARE NEEDED TO BE IN A CONTROLLED PATTERN OF HEAT RADIATION
35 (MORE AT CENTER AND LESSER AT EDGES) TO WARD OFF ROUGHNESS OF
COATING AND EDGE BLISTERS.
(XIII) THE MOST CONCERN IS STRIP TEAR OR STRIP BREAKAGE AT STITCH JOINT WHICH
WILL RESULT IN A PILE UP OF STRIP ON THE FLOOR WITH THE UNAVOIDABLE
40 DAMAGES TO THE COATING EQUIPMENT, SCORING THE OVEN EMITTER REFLECTOR
SHELDS AND BREAKAGE OF EXPENSIVE QUARTZ GLASS SHELD.
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(XIV) NEXT IS THE TENSION FLUCTUATIONS AT COATING ROLL UNIT WRAP-AROUND DRUM WHERE SELF WEIGHT OF THE STRIP COULD BE OF VARYING NATURE AFFECTING THE TENSION OF THE WRAP-AROUND DRUM OR AT DEFLECTOR ROLL LOCATIONS IN THE COATER AREA OR A VERTICAL UP PASS LINE AND A VERTICAL
5 DOWN PASS UNE.
(XV) EVERY CURING OVEN OR HEATING APPARATUS HAS TO BE OPERATED WITH A
SPECIFIED VOLUME RATE OF HEATED OVEN AIR THROUGH THE OVEN TUNNEL. THE
VOLUME RATE IN NM3/HOUR IS NEEDED TO MAINTAIN LEL VALUES (LOWER
10 EXPOSIVE LIMIT) NOT EXCEEDING 25% AND THE TEMPERATURE IN RADIATION
OVENS EMPLOYING SOLVENT WILL HAVE TO BE MAINTAINED AT ABOUT 250°C TO AVOID SOLVENT SOLIDIFICATION IN OVEN INTERIOR AND AS PER THE SAFETY NORMS.
15 IN THE VERTICAL FURNACE CONFIGURATION: THE OVEN AIR SUCTION PORT IS IN
THE ENTRY SECTION OF THE FURNACE. HOT OVEN AIR ENTERS FROM THE EXIT OF FURNACE AT TOP AND IS SUCKED OFF AT THE BOTTOM. A HIGH NEGATIVE
PRESSURE IS MAINTAINED IN SUCH FURNACES. THE GUSH OF HOT OVEN AIR DOWNWARD DRAFT CERTAINLY COULD DISTURB UPCOMING COATINGS.
20 SECONDLY, THE DOWARD DRAFT CANNOT EFFECTIVELY SUCK IN OUTSIDE AIR FOR
DILUTION TO MAINTAIN AT LEAST 11% TO 12% OXYGEN IN THE SOLVENT-LADEN AIR FOR THERMAL OXIDATION OR INCINERATION. IT THEREFORE FOLLOWS THAT 50% OF INJECTION OF HOT OVEN AIR WITH BALANCE OVEN AIR SUCKED FROM OUTSIDE ENVIRONMENT MAY NOT BE POSSIBLE AND FULL COLD AIR IS TO BE
25 DRAWN IN WITH ADDED FUEL FOR HEATING THE OVEN AIR BY HOT AIR
GENERATORS AND HEAT EXCHANGERS TO PRESENT THE TEMPERATURE OF 250°C OR 260°C OF HOT OVEN AIR INTO THE EXIT OF VERTICAL OVEN.
(XVI) SUCH A DOWNWARD DRAFT AT HIGH TEMPERATURE CAN ALSO DISLODGE MORE OF
30 THE EMITTER REFLECTIVE SHIELDS TERMED "RSS" WHICH HAS A TENDENCY TO
DISTORT OR LOCALLY MELT NEEDING MUCH MORE REPLACEMENTS. BUT MORE SERIOUS IS THEIR FALLING DOWN WHICH ARE INJURIOUS TO FLOOR PERSONNEL IN COATING CABIN AREA.
D. EMBODIMENT OF THE PRESENT INVENTION WITH HORIZONTAL INFRA RED OVEN:
(I) SO FAR IN THE HISTORY OF NEAR INFRA RED/ INFRA RED OVEN
40 CONFIGURATION FOR A FULL SCALE COATING OPEARTION THERE HAS BEEN NO
ATTEMPT TO CONFIGURE THE HORIZONTAL ORIENTATION OBVIOUSLY WITH THE
STRIP PASS LINE IN HORIZONTAL FASHION. THE EFFECT OF SAG OF STRIP WHICH
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IS DETRIMENTAL TO UNIFORM SURFACE HEATING OF STRIP ON TOP AND BOTTOM AND TENSION FLUCTUATIONS DUE TO VARYING STRIP CORSS SECTIONS ON UNSUPPORTED LENGTH OF AT LEAST 25 METERS TO 30 METERS HAS BEEN BELIEVED TO BE THE UNDERLYING CAUSE.
(II)SUCH A HORIZONTAL CONFIGURATION THE HEATING APPARATUS HAS BEEN
TESTED PARTLY CALLING A "BOOSTER OVEN" BY INSTALLING AT THE NIR OVEN IN LINE WITH A CONVENTIONAL CATENARY OR FLOATATION OVEN AT HIGH SPEEDS. THE BOOSTER WAS PLACED IN THE ENTRY SECTION OF AN EXISTING CONVENTIONAL GAS HEATED OVEN FOLLOWING THE STRIP PASS LINE PROFILE OF
THE CATENARY AT OBVIOUSLY LOW TENSION THE REPORTS OF SURFACE DEFECTS OF EDGE BLISTERS AT THE OPERATING SPEEDS HAD BEEN PERSISTENT.
(II)BUT THOSE IN THE ART OF MACHINERY PROCESS DESIGN ARE QUITE AWARE THAT AMOUNT OF SAG CAN BE MINIMISED BY THE STRIP TENSION WHICH FOR A CATENARY EFFECT VARIES PROPORTIONATELY TO THE SQUARE OF THE SPAN AND INVERSELY TO THE DEPTH OF SAG. IN OTHER WORDS, THE STRIP TENSIONS NEEDED GOES BY THE RELATION:
SPECIFIC TENSION IN KG/MM2 IS EQUAL TO :
DENSITY OF STRIP X SPAN2 K x DEPTH OF SAG
WHERE:
K IS A CONSTANT
DENSITY: STRIP MATERIAL IN KG/MM3 OR POUNDS PER INCH CUBE
SPAN: DISTANCE FROM THE TOUCH POINT OF TURNOVER DRUM TO THE FIRST
COOLING ROLL OF THE QUENCH TANK OR UPTO THE CENTER LINE OF BRIDLE
N0.1 ROLL AT EXIT OF WATER QUENCH TANK AND DRIER EXPRESSED IN MM OR
INCHES.
(IV) IT IS ALSO KNOWN IN THE PRACTICE OF LINE DESIGN THAT TENSIONS ARE
EMPLOYED FOR CONTROLLED ELONGATION IN TENSION LEVELLING APPLICATION TO THE EXTENT OF 30% TO 35% OF THE YIELD STRENGTH OF MATERIAL.
(V) WHEN THE STRIP SURFACE TENSION EQUALLING THE CONDITION OF M-(lll) ARE
EMPLOYED IN THE HORIZONTAL OVEN THE SAG OF STRIP HAS BEEN WELL
11 of 30

CONTAINED WTTHIN 70 TO 75 MM. WHERE OVENS ARE ALWAYS DESIGNED FOR + 100 MM VARIATION OF STRIP PASS LINE. THIS STARTLING EFFECT OF HIGH STRIP TENSIONS HAS GIVEN A STRING OF OPPORTUNITIES WITH EASY OPERATING SOLUTIONS TO ACHIEVE EXCELLENT QUALITY OF PAINT COATED PRODUCTS NEVER BEFORE ATTEMPTED OR REALISED.
(VI) A USEFUL AND SURPRISING COROLLARY OF THE INVENTION IS THAT THE HEATING APPARATUS THROUGH WHICH THE STRIP PASSES WITH HIGH TENSION CAN BE INSTALLED WITH A SLOPE FOLLOWING THE STRIP PASS LINE WHERE THE SO CALLED SAG FALLS AT THE OVEN EXIT FURTHER ENHANCING THE QUALITY OF UNIFORM HEATING.
(VII) THE HORIZONTAL HEATING NEAR INFRA RED APPARATUS HAVING A CURING
TIME RANGING FROM 1.5 TO 3.0 SECONDS WILL NEED AN OVEN LENGTH PROPORTIONAL TO LINE SPEED FOR INDUSTRIAL FINISHES OF COIL COATING:

FOR EXAMPLE •
LINE LENGTH OF
SPEED OVEN
(M/MlN.) (MAXIMUM) IN
METERS
60 3
120 6
180 9
220 12
(VIII) ABOVE IS AN INDICATION THAT A TIGHT STRIP WITH WORKABLE HIGH TENSIONS RESTRICTS THE SAG INSIDE THE FURNACE TO MINIMUM LIMITS SUPPLEMENTED
BY JUDICIOUS SLOPING OF THE HEATING APPARATUS ALL CONTROLLABLE AT WILL BY OPERATOR IN A MOST EASY AND RAPID MANNER WITH MODERN GADGETS, ACTUATORS AND FEEDBACK SENSORS.
(IX) FURTHER ADDED FLEXIBILITY IS THE OPTIONAL MECHANICAL/ HYDRAULIC/ ELECTRIC ADJUSTEMENTS OF THE OVEN WHICH WITH POSITION TRANSDUCERS
12 of 30

AND AUTOMATIC ADJUSTMENTS WITH WEDGE/ SCREWS AND ELECTRIC/ HYDROMOTOR ACTUATORS, CAN BE TILTED ON A X-Y-Z AXIS TOWARDS THE OPERATING SIDE FROM MINUTES OR DRIVE SIDE BY A FEW DEGREES TO THE
CONVENIENCE OF THE OPERATOR IN A CALCULATED MANNER.
5
(X) LIKEWISE, THE OVEN CAN BE TILTED FROM EXIT TO ENTRY IN A CALIBRATED AND
CALCULATED MANNER.
(XI) WITH SUCH A POSSIBILITY OF OVEN ASSEMBLY CONFIGURATION ADJUSTMENTS,
10 YET ANOTHER POSSIBILITY IS THE HEATING BRIDGES HOUSING THE EMITTER
LAMPS. THE BRIDGES CAN BE ALTERNATED TOP AND BOTTOM IN STRAIGHT
LENGTHS CONVENTIONALLY IN A STAGGERED AND DISPLACED FASHION AND WITH
YET ANOTHER OPTION OF THE BRIDGE WITH ITS HEAT ELEMENTS AND
REFLECTORS CONVEXED OR CONCAVED OR ALTERNATIVELY CONVEXED OR
15 CONCAVED. SUCH AN ARRANGEMENT CAN BE APPRECIATED BY THOSE WEKNOWN IN THE ART TO PRODUCE A VARIETY OF WAYS FOR CONTROLLED
RADIATION HEAT ON STRIP SURFACE TO CURE A WIDE RANGE OF PAINTS IN SHADES AND COATING THICKNESS AS CURING POSSIBILITY FOR ACHIEVING FLAWLESS PAINT COATED CURED SURFACE.
20
(XII) YET ANOTHER OBJECT OF INVENTION IS THAT WITH THE HIGH STRIP TENSION EMPLOYED, SURPRISINGLY THE APPLICATION PRESSURES ON THE STRIP BY COATING ROLLS AND THE PRESSURE OF PICK UP ROLL ONTO COATING ROLL IN A REVERSE OR DIRECT COATING TECHNIQUE HAS BEEN QUITE CONVENTIONAL
25 WITHOUT RESORTING TO HIGHER PRESSURE OF 20 TO 30 KILONEWTONS
VALUES. PRESSURE APPLIED ARE MUCH LESS THAN 1 BAR VALUE (1 TO 3 KJLONEWTON) AND THE CURED PRODUCT AT ALL SPEEDS HAVE EXCELLENT QUALITY.
30 IT IS TO BE EXPLAINED THAT THE WRAP-AROUND OF STRIP ON TURNOVER
DRUM AT HIGH STRIP TENSIONS PROVIDES AN EVEN AND FLAT SURFACE OF SUCH MAGNITUDE THAT PAINT APPLICATION HAS TURNED OUT TO BE EFFORTLESS.
35 (XIII) WITH SUCH A CONFIGURATION OF STRIP UNDER TENSION THE OVEN VESTIBULE
LENGTH NECESSITY EXCEPT FOR SAFETY OR MECHANICAL NEEDS IS BAREST MINIMUM AS THE PAINT FLOW OUT HAS TURNED OUT TO BE SMOOTH NEEDING NO ADDITIONAL FLOW OUT TIME TILL IT ENTERS THE OVEN.
40 (XIV) YET ANOTHER OBJECT OF THE INVENTION IS THE IMPROVED QUALITY
CONTRIBUTION IN THE ACCEPTABLITY OF THE FAVOURABLE MIXTURE OF HAVVY SOLVENT THINNERS IN CERTAIN PROPORTIONS WHICH WHEN ADDED TO THE
13 of 30

PRIMER AND FINSHER PAINTS SPECIFICALLY DEVELOPED WITH FAST CROSS
LINKING OF POLYMERS FOR NIR OVEN DEMANDS OF SHORT CURING TIMES
HAVE CONTRIBUTED REMARKABLY IN THE ELIMINATION OF CRATERING,
FEATHERY MARKS, ROUGH COATED SURFACE, GLOSS REDUCTION, MEK RUB
5 FAILS AND CUPPING & BENDING TEST FAILURES WHEN APPLIED ON THE HIGH
TENSIONED STRIP WITH MINIMUM VESTIBULE CONDITION.
E ADVANTAGES OF THE METHOD OF USAGE AND PROCESS OF HORIZONTAL NEAR INFRA
10 REP OVENS BY THE PRESENT MODE OF INVENTION:
a. OVENS CAN BE LAID OUT ON FLOOR ONE AFTER OTHER, I.E., PRIMER CURING
OVEN WITH ITS AUXILIARIES FOLLOWED BY FINISHER CURING OVEN WITH
15 AUXILIARIES.
OR
PRIME CURING OVEN WITH AUXILIARIES ON TOP OF FINISH CURING OVEN
WITH ITS AUXILIARIES.
20
b. ALL HEATING BRIDGES ARE PULLED OUT HORIZONTALLY AT THE SAME OVEN FOR
ELEVATION FOR EASY CLEANING & MAINTENANCE.
c. DAMAGED QUARTZ OR REPLACEMENT OF RSS SHIELDS ARE EASY AT FLOOR
25 LEVEL AND NO SAFETY DANGERS SUCH AS FACED IN VERTICAL OVENS.
d. HIGH STRIP TENSIONS OF THE ORDER OF 8.5 KG/MM2 TO 14 KG/MM2 HAVE BEEN
SUCCESSFUL IN MANY WAYS.
30 i. CATENARY SAGS HAVE BEEN VIRTUALLY ELIMINATED.
ii. COATED STRIP QUALITY BY THIS HIGH TENSION STRIP DYNAMICS WITHOUT
TOUCHING ANY SUPPORT OBJECT TILL WATER QUENCH HAS PRODUCED
FLAWLESS COATED SURFACE AT ALL SPEEDS.
iii. FURTHER THE FLEXIBILITY OF MECHANICAL GADGETS IN SLOPING OF THE
35 OVEN OR CANTING AS DESCRIBED EARLIER ADDS TO THE FLEXIBILITY AND
CONTROL OF RADIATION HEAT ON STRIPS.
iv. ADDITIONAL WAYS OF CONTOURED BRIDGES BY WAY OF STRAIGHT
LENGTH, CONVEXED OR CONCAVED ALTERNATIVELY OR TOGETHER,
STAGGERED AND DISPLACED TOP AND BOTTOM IS YET ANOTHER
40 FLEXIBILITY OF CONTROLLED HEATING OF STRIP SURFACE ALONG WIDTH
FOR SHORT CYCLE OF RESIDUE TIME IN OVEN FOR ACHIEVING THE PEAK
METAL TEMPERATURE.
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v. THE APPLICATION OF COATING PRESSURE ON THE STRIP HAS BEEN
SURPRISINGLY LOW AND NORMAL.
vi. FURTHER, MIXING OF HEAVY SOLVENT THINNERS HAVE HAD A GREAT
EFFECT IN THE ELIMINATION OF CRATER FORMATION, COATING POP UP,
5 BUCKLE, ROUGH SURFACE WITH SMOOTH OPERATION OF CROSS-LINKING
PHENOMENON WITH THE HIGH TENSION STRIP DYNAMICS.
vii. STITCH PASS THROUGH OVEN AT THIS TENSION HAS NO PROBLEM AS
DOUBLE STITCH PRACTICE CAN BE ADOPTED IF NEEDED TO PREVENT
STITCH FAILURE.
10 Viii. STRIP BREAKAGE AT ANY POINT IF OCCURRED POSE NO DANGER TO THE
HEATING APPARATUS AS IN THE CASE OF VERTICAL HEATING APPARATUS.
ix. COATING QUALITY CONTROL BOTH MANUAL AT ANY POINT OF TIME IS
RENDERED EASY AT FLOOR LEVEL OR OVEN FLOOR LEVEL.
X. THE GREATEST MECHANICAL BENEFIT IS THAT WITH HIGH STRIP TENSIONS,
15 ONCE STRIP IS CENTERED, STEERING MECHANISM HAVE VERY LITTLE ROLE
TO PLAY AND STRIP MOVEMENT THROUGHOUT PROCESS SECTION IS IN DEAD CENTER.
e. ADVANTAGES OF ACCOUNT OF EMITTER COOLING POCKETS INCLUDING CRITICAL
20 PARTS OF BRIDGES BY CLOSED WATER COOLING CIRCUITS AT FLOOR LEVEL ARE
EASIER FOR FEED WATER PRESSURE SUPPLIES AS AGAINST VERTICAL OVENS
WHERE WATER IS TO BE PUMPTED AT HIGHER LEVELS WITH BOOSTER.
f. AN AIR EXHAUST FOR FUMES OF OVEN AIR AT EXIT OF THE OVEN CLOSELY LAID
25 OUT IS BENEFICIAL IN CATCHING THE DRAG OUT FUMES FROM STRIP AT HIGH
SPEEDS WHICH CAN BE SAFELY CONNECTED TO THE THERMAL OXIDATION SYSTEM OF THE SOLVENT.
g. THE FLOW OF OVEN AIR THROUGH TUNNEL OF NIR WITH ITS INTERNAL NEGATIVE
30 PRESSURE HAS THE EASY WAY OF COATING CABIN AIR INTAKE DILUTING THE
OVEN AIR WHICH TOGETHER WITH MIXING OF HOT AIR FROM COOLING OF EMITTERS PROVIDE AN EXCELLENT ENVIRONMENT OF AUTOTHERM CONDITION WITH ZERO FUEL OPERATION.
35
40
15 of 30


F. MAIN LINE PARAMETERS:
OPERATING SPEED IN MINUTE:
5 1 .ENTRY SECTION
: 220 M/MINUTE
2. PROCESS SECTION
: 180 M/MINUTE
3. DELIVERY SECTION
10 :220 M/MINUTE
4. STRIP WIDTH
: 600 MM TO 1300 MM
5. STRIP THICKNESS
: 0.15 MM TO 1.25 MM
15 6. COIL WEIGHT
: MAX 20,000 KG.
7. COIL I.D. ENTRY & EXIT
:508MM
8. COIL O.D. ENTRY & EXIT
20 :2000 MM
TABLE 1: LINE EQUIPMENTS

16 of 30



5 TABLE-2: PARAMETERS COVERING EMBODMENT OF INVENTION

17 of 30


PER SE, IT IS CONFIRMED THAT SHREE PRECOATED STEELS LTD, PUNE HAS
ESTABLISHED THE FIRST COLOUR COATING LINE AT THE HIGHEST SPEED WITH THE
5 HORIZONTAL NEAR INFRA RED OVEN FOR PRMER, FINISHER ETC. WITH HIGH STRIP
18 of 30

TENSION WITH NORMAL APPLICATION PRESSURE OF COATING ROLL WITH MODIFIED NIR PAINT WITH HEAVY SOLVENT THINNERS WHO WORK ON THE CONDITIONS GOVERNED BY THE EMBODIMENT OF THIS INVENTION.
G - .IT WILL BE APPRECIATED THAT VARIOUS CHANGES MAY BE MADE IN THE FORM OF
THE INVENTION SHOWN IN THE DESCRIPTION OF THE EMBODIMENT OF THIS INVENTION AND SKETCHES AND DRAWINGS HEREIN.
10 (I) IF DESIRED THE OVENS CAN BE PLACED IN A HORIZONTAL FASHION ONE AFTER THE
OTHER PRIMER OVEN FOLLOWED BY FINISHER NIR OVEN OR THE PRIMER OVEN IS PLACED BELOW THE FINISHER OVEN QR THE HEATING APPARATUS COULD BE A COMBINATION OF ULTRAVIOLET AND NIR OVEN COMBINATION PLACED FOR A HORIZONTAL STRIP PASS UNE THROUGH THE SAME.
15

(II)

IT IS ALSO IN THE EMBODIMENT OF THIS INVENTION THAT THE UNSUPPORTED SPAN OF STRIP LENGTHS THROUGH THE HORIZONTAL WITH ITS AUXILIARIES COULD EXCEED 25 TO 50 METERS OR ON THE CONTRARY COULD BE SHORTER.

20 .(III) POR INSTANCE, HEATING BRIDGES MAY BE SUBSTITUTED BY OTHER TYPES OF REFLECTORS WITHIN THE CONCEPT OF HORIZONTAL HEATING APPARATUS, SUCH AS REFLECTOR FLAT ALUMINIUM-POLISHED OR ADDITIONALLY GOLD-PLATED FLAT PROFILES ARE PARABOLIC SHAPES OR SPECIAL REFRACTORY COATED ALUMINIUM SURFACES HIGHLY POLISHED AND SELF CLEANING TYPE.

(IV)
THERE COULD BE HEAVY SOLVENT THINNERS IN THE MARKET BUT TO MIX THEM
IN THE PROPER RATIO IS CONDUCIVE FOR THE HIGH STRIP TENSION OPERATION
HAVING NO CONSEQUENCE OF THE FLOW-OUT TIME NEEDED BY OTHER METHODS AS
DESCRIBED ABOVE AND ADVANCE OF SURFACE DEFECTS AT HIGH SPEEDS SUCH AS
30 CRATERS, MEK RUB FAIL, BLISTERS AT EDGES, PAINT POP UP AND SURFACE
ROUGHNESS ETC.

(V)-
(MODIFICATIONS MAY OF COURSE BE MADE WITHIN THE RANGES ABOVE DESCRIBEAND WE THEREFORE DO NOT INTEND TO UMIT OURSELVES EXCEPT AS SET FORTH IN
35 THE CLAIM, WHICH FOLLOWS.
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VI

ALL ARE COVERED WITHOUT DEPARTING FROM THE SPIRIT AND SCOPE OF THIS INVENTION AS DESCRIBED IN THE APPENDED CLAIMS.

H. SUMMARY OF THE EMBODIMENT OF THE INVENTION:
THE EMBODIMENT OF THE PRESENT INVENTION IS EMPLOYING THE HEATING APPARATUS, I.E., NEAR INFRA RED OVEN OR A MULTIPLE THEREOF IN A HORIZONTAL
10 FASHION WITH HIGH STRIP TENSION DYNAMICS WITH RANGE OF MINIMUM 30% TO 35%
OF THE YELD STRENGTH OF THE MATERIAL TO LIMIT THE CATENARY SAG OF STRIP IN THE RANGE OF 50 MM TO 100 MM WITH CATENARY FALUNG OUTSIDE THE OVEN AND SLOPE THE OVEN ASSEMBLY WITH THE MECHANICAL GADGETS SHOWN IN SKETCHES ATTACHED TO THE INVENTION AND LOCATE THE SUBSEQUENT AUXILIARIES FOLLOWING
15 THE STRIP PASS CONFIGURATION, I.E., SLOPE UP THE AIR QUENCH TOUCH ROLL AND
WATER QUENCH ASSEMBLY SO AS TO FORM A SMOOTH COATED, CURED AND FINISHED STRIP WHICH ONLY WITH HIGH STRIP TENSION WRAP-AROUND THE TURN OVER DRUM
ON WHICH THE APPLICATOR ROLL IS EMPLOYED FOR COATING NEEDS MINIMUM APPLICATOR ROLL PRESSURE OF ONLY 1.0 TO 3.0 KlLONEWTON RANGE AND
20 ESSENTIALLY OPERATED IN POSITION MODE OR WITH PRESSURE MODE AS DESIRED
WITH PICK UP ROLL PRESSURES ON APPLICATION ROLL RANGING FROM 12 KlLONEWTON TO 30 KlLONEWTON AT CONTINUOUS LINE SPEEDS MATCHING SAY 200 METERS PER MINUTE OR OVER OR UNDER WITH APPLICATOR ROLL SPEED RANGING FROM 120% TO 130% OF LINE SPEEDS AND PICK UP ROLLS RUNNING AT 25% TO 30%
25 LINE SPEED WITH WHICH INVENTION ONLY NIR PAINTS SPECIALLY FORMULATED WITH
FASTER CROSS LINKING PROPERTIES WILL BE APPLIED WITH PROPRIETARY HEAVY SOLVENT THINNERS OF GLYCOL, CARBITOL COMBINATION EFFECTIVELY PREPARED WITH AN AMOUNT OF UNIVERSAL THMNERS OR ELSE AS A SINGLE COMPOUND OR IN A READY-MIXED COMBINATION TO PRODUCE A COATED SURFACE DEVOID OF SURFACE
30 ROUGHNESS, MEK FAILURES, EDGE BLISTERS, PAINT CRATERS OR POP UP OR
DECREASED GLOSS WITHIN THE CHOSEN OVEN CAPABILITY (I.E., NIR OVEN, IR OVEN, UV OVEN, INDUCTION HEATED OVEN OR A COMBINATION THEREOF) WITH NO CONSIDERATION ON THE LENGTH OF THE ENTRY VESTIBULE TO THE OVEN RELATING TO THE FLOW-OUT TIME OF WET PAINT EXCEPT AS DICTATED BY EQUIPMENT LAYOUT OF
35 THE WHOLE LINE.
20 of 30

I. NEW ITEMS USED IN MODIFICATION/ IMPROVEMENTS: ■ NEW EQUIPMENTS & PROCESS COVERED UNDER THE EMBODIMENT OF THIS
PATENT OF MODIFICATION AND IMPROVEMENT : 5
A. NEW EQUIPMENTS:
1.
a. POWERFUL BRIDLES AT ENTRY AND DELIVERY SIDES OF THE HEATING OVENS AND
10 BEFORE THE PAINT COATER HEADS POWERED TO PRODUCE HIGH TENSION IN THE STRIP
UP TO 35% OF YIELD STRENGTHS OF THE MATERIAL TO RUN STRIP TIGHT IN THE OVENS WITHOUT CATENARY SAG OR WITH LEAST CATENARY SAG.
b. SUCH TENSIONS REMOVE THE CATENARY EFFECT AND CONTRIBUTE TO UNIFORM
15 HEATING OF TOP AND BOTTOM SIDES OF THE COATING FROM NEAR INFRA RED/ INFRA
RED/ UV CURING OVENS.
c. SPECIFIC TENSIONS APPLIED ARE MONITORED BY LOAD CELLS IN BRIDLES AND
AUTOMATED TO THE TOTAL TENSION VALUES NEEDED FOR ANY STRIP GEOMETRY. 20
2.
a. MOUNTING OF MECHANICAL GADGETS BY HYDRAULIC MOTOR ACTIVATED DOUBLE
WEDGE BENEATH THE OVEN ASSEMBLY OR BY SCREW JACK ASSEMBLIES
INTERCONNECTED WITH EACH OTHER BY DRIVES WITH POSITION TRANSDUCERS
25 ACHIEVES THE FOLLOWING:
i. MECHANICAL/HYDRAULIC LIFTING OF OVEN ASSEMBLY SO THAT THE STRIP IS
IN CENTER LINE OF OVEN AT ALL TIMES.
30 ii. A TWIST IN THE STRIP AT HIGH SPEEDS UP TO 15° CAN BE COUNTERED BY
CANTING THE OVEN FROM OPERATING TO DRIVE SIDE OR VICE-VERSA TO ESTABLISH RECEIPT OF UNIFORM HEAT FROM THE HEAT SOURCE OF EMITTER BRIDGES.
35 iii. SHOULD A SLIGHT CATENARY DO OCCUR, THE OVEN ASSEMBLY CAN BE
TILTED FROM ENTRY TO EXIT BY FRACTIONS OF A DEGREE TO OBVIATE THE EFFECT BY THE MECHANICAL GADGETS NEW OUTLINED IN THE EMBODIMENT.
3.
40 a. HEAT SOURCE FROM THE EMITTERS THROUGH REFLECTOR HOUSWG ARE NORMALLY
MOUNTED ABOVE AND BELOW THE STRIP M HORIZONTAL FASHION, CALLED HEATING BRDGE.
21 of 30

b. IT IS KNOWN IN THE ART OF PAINT CURING THAT IN SHORT TIMES, EDGE BLISTERS AT HIGH SPEEDS ARE EXPECTED IN A BIGGER SCALE WHERE HEAT POWER SOURCE ACROSS THE WIDTH IS TRIMMED.
5
C. IT IS, THEREFORE, PROPOSED TO HAVE BRIDGES IN A CONVEXED AND CONCAVE
PATTERN. THE CROWN CAN BE UNIFORMLY RACIALLY CURVED (RADIAL CROWN) OR
1/3 FLAT MIDDLE AND BALANCE TAPERED TOWARD THE END (TAPERED CROWN) FOR
BOTTOM HEATING OF STRIP AND TOP SIDE HEATING OF STRIP. THE CROWN RANGING
10 FROM 2 PERCENT TO 10 PERCENT OF THE DISTANCE BETWEEN THE HEATING SOURCE
(EMITTER LAMPS) AND THE SURFACE OF THE STRIP. REST OF HEAT ADJUSTMENT BY SELECTION OF EMITTERS ON THE BRIDGE ARE AS PER CONVENTIONAL PRACTICE INCLUDING CUTTING OFF HEAT SOURCE PORTION SELECTIVELY.
15
4.
a. DISPOSITION OF THE HEATING SOURCE CAN BE MADE SUCH THAT ONE SET OF BANKS
HEAT THE STRIP SURFACE ONLY AT THE TOP TO CURE THE WET PAINT WHEREAS THE
SECOND SET OF BANKS CAN BE USED TO CURE THE PAINTED STRIP FROM BOTTOM
20 SUBSEQUENTLY FOLLOWING THE FIRST BANK OF HEATING TO MAINTAIN UNIFORM
ABSORPTION OF POWER FROM THE COATED SURFACE SO THAT UNCOATED SURFACE DOES NOT LIMIT THE TOP COATED SURFACE FROM UNDUE OVER HEATING OF METALLIC STRIP ELIMINATING TRIPPING OF BOTTOM BRIDGES.
25
B. PROCESS IMPROVEMENTS:
1. VERY LOW APPLICATOR ROLL PRESSURE IS ONLY NEEDED IN THE RANGE OF 1
TO 3 KILONEWTON TO COAT PAINT ON STRIP WITH HIGH STRIP TENSIONS VIS-A-VIS HIGH SPEED LINES WITH CONVENTIONAL OVENS NEEDING MORE THAN 10 TO 20 TIMES THE PRESSURE, RESULTING IN INCREASED LIFE OF ROLL, STABLE ROLL SURFACE AND PAINT TEMPERATURE AND VISCOSITY OF PAINT, RESULTING IN STABILISED OVEN HEATING PARAMETERS AND CONSISTENT QUALITY PRODUCTION AT HIGHER SPEEDS.
35 2. THE NIR FORMULATED PAINT ADJUSTED TO CORRECT VISCOSITIES WHEN WITH
THE ABOVE STRIP CONDITION APPLIED HAS AN ASTOUNDING EFFECT WHEN MIXED WITH HEAVY SOLVENT THINNERS IN THE RATIO OF ADDED THINNER PERCENTAGE OF 5% TO 15% DEPENDING ON THE GRADES AND SHADES OF PAINT FOR INDUSTRIAL FINISHES BY ELIMINATING MANY OF THE HIGH SPEED DEFECTS, SUCH AS CRATERING, POP UP AND
40 BLISTERS AT EDGES AND AT TIMES SURFACE ROUGHNESS. THE HEAVY SOLVENT THINNER
IS A MIXTURE OF PROPYLENE GLYCOL - METHYL ETHER AND BUTYL CARBITOL ACETATE AND A SMALL PORTION OF UNIVERSAL THINNER.
22 of 30

3. BY MAINTAINING THE STRIP GEOMETRY AT HIGH TENSIONS, THE CONVENTIONAL
FLOW OUT TME NEEDED BEFORE WET PAINTED STRIP ENTERING THE OVEN RESULTING IN
A LONG ENTRY VESTIBULE OF 3 SECONDS FLOW-OUT TIME (E.G., AT 180 METERS/
5 MINUTE: 9 METERS) IS NO LONGER NEEDED. THAT IS, ENTRY VESTIBULE OF 9 TO 12
METERS LONG ATTACHED AT ENTRY OF THE OVEN IS ELIMINATED. ONLY A SMALL PIECE OF THROAT AT THE OVEN ENTRY DICTATED BY PAINT CABIN ENTRANCE OPENING LOCATION IS ALL THAT IS NEEDED, SAY 1.5 TO 2 METERS.
J. HAVING FULLY DESCRIBED THE INVENTION WHAT WE CLAIM:
15
1. A CONTINUOUS COATING LINE COMPRISING BRIDLE 1, PRIME COATER, PRIME OVEN WITH HEATING MEANS, QUENCHING TANKS, DRIER 1, BRIDLE 2, T-TYPE AND S-TYPE COATERS, FINISH OVEN WITH HEATING MEANS AND FURTHER QUENCHING TANKS, DRIER 2 AND BRIDLE 3 WHEREIN THE BRIDLES ARE CAPABLE OF APPLYING HIGH
20 TENSION UP TO V3 OF YIELD STRENGTH OF STRIP MATERIAL BEFORE AND AFTER
HEATING APPARATUS TO ELIMINATE SAG OVER UNSUPPORTED SPAN OF 25 TO 70 METERS.
2. THE DEVICE OF CLAIM 1 WHEREIN ACTUATORS WITH LIFTING GADGETS ARE PROVIDED
25 TO TILT THE OVEN IN STEPS OF FACTION OF DEGREES FROM ENTRY TO EXIT IN THE
DIRECTION OF STRIP FLOW OR VICE VERSA TO ACCOMMODATE EVEN THE SLIGHT SAG ARISING OUT OF UNSUPPORTED SPAN RANGE OF THE STRIP.
3. THE DEVICE OF CLAIM 2 WHEREIN THE LIFTING GADGETS ARE HYDRAULICALLY
30 OPERATED POSITION TRANSDUCERS.
4. THE DEVICE OF CLAIM 1 WHEREIN CENTRE UNE OF THE STRIP IS MAINTAINED BY
PROVISION OF LIFTING OR LOWERING GADGETS FOR THE HEATING APPARATUS.
35 5. THE DEVICE OF CLAIM 1 WHEREIN HEATING MEANS IS ELECTRICAL RADIATING SOURCE.
6. THE DEVICE OF CLAIM 5 WHEREIN THE HEATING MEANS ARE INFRA RED OR ULTRA
VIOLET CURMG LAMPS ARRANGED M CONCAVE OR CONVEX FASHION ON TOP AND
BOTTOM OF THE STRIP MATERIAL TO ALTER THE RADIATION HEAT INPUT IN FLEXIBLE
MANNER.
23 of 30

7. A PROCESS OF CONTINUOUSLY COATING METAL STRIP COMPRISING THE FOLLOWING STEPS:
5 i. CLEANING THE STRIP WITH ALKALI.
ii. APPLYING PRIMER COATING AND BACK COATING OF 5 TO 8 MICRONS ON TOP AND BOTTOM SURFACES, RESPECTIVELY AND 20 TO 22 MICRONS FINISH COATING ON TOP AND BOTTOM SURFACE.
Hi. PASSING THE STRIP THROUGH HORIZONTAL HEATING FURNACE/ NEAR INFRA
10 RED OVEN HAVING A SHORT CURING RESIDENCE TIME OF 1.5 TO 3 SEC.
iv. AIR QUENCHING AND WATER QUENCHING THE STRIP CHARACTERISED IN THAT
THE STRIP IS GIVEN AFTER FINISH PAINT COATING BY APPLYING HIGH STRIP
TENSIONS IN THE RANGE OF 30% TO 35% OF THE YIELD STRENGTH OF STRIP
MATERIAL IN FURTHER SECTION OF THE HEATING APPARATUS FOR MINIMISING
15 CATENARY SAG BY USING POWERFUL TENSION BRIDLES.
8. THE DEVICE OF CLAIM 1 WHEREIN THE OVEN/HEATING APPARATUS HAS HYDRAULICALLY ACTUATED POSITION TRANSDUCERS TO TILT THE FURNACE FROM OPERATING TO DRIVE SIDE OR DRIVE TO OPERATING SIDE. 20
9. THE DEVICE OF CLAIM 1 WHEREIN PRACTICAL CENTRE LINE OF THE STRIP IS MAINTAINED BY LIFTING OR LOWERING THE HEATING APPARATUS BY MECHANICAL
GADGETS.
25 10. A DEVICE OF CLAIM WHEREIN THE STRIP USED IN THE PROCESS IS IN THE FORM
OF GALVANISED SUBSTRATE, ZINC-ALUMINIUM ALLOY SUBSTRATE, COLD ROLLED STEEL HARD OR ANNEALED, STAINLESS STEEL, ALUMINIUM OR ALUMINIUM ALLOY STRIP.
11. A CONTINUOUS COATING LINE SUBSTANTIALLY AS HEREIN DEFINED AND
30 ILLUSTRATED IN THE FIGS. OF THE ACCOMPANYING DRAWINGS.
35 40
12. A PROCESS OF CONTINUOUSLY COATING METAL STRIP SUBSTANTIALLY AS
HEREIN DEFINED.

24 of 30

ABSTRACT OF THE INVENTION
(I) ESSENTIALLY, THE INVENTION IS RELATED TO THE TREATMENT OF STRIP TENSION DYNAMICS TO VALUES NEVER BEFORE EMPLOYED ON A HORIZONTAL OVEN SPECIFICALLY THE HIGHLY SENSITIVE NEAR INFRARED/ INFRARED RADIATION/ INDUCTION HEATED CURING OVEN DEVICE OR NEAR INFRA RED/ ULTRA-VIOLET RADIATION CURING OVEN OF SOLVENT- BASED PAINTS/ WATER BASED PAINTS/ POWDER COATINGS WITH A CAPABILITY TO ATTAIN CURING TEMPERATURE MEASURED AS PEAK METAL TEMPERATURE FOR THE FINISH NEEDS IN A TIME OF TWO TO THREE SECONDS.
(II) IT is YET ANOTHER OBJECT OF INVENTION TO MAINTAIN HORIZONTAL PASS LINE AND PATH OF STRIP TRAVEL, PAINT COATED STRIP ON ONE SIDE AND TWO SIDE COATINGS WITH THE HORIZONTAL OVEN ORIENTATION, EITHER HORIZONTAL CONFIGURATION OR WITH CALCULATED SLOPE IN THE DIRECTION OF STRIP TRAVEL AND/OR MOUNTING THE OVEN WITH SUCH MECHANICAL GADGETS AND POSITION TRANSDUCERS TO SWING OR TILT THE HORIZONTAL OVEN COMPLETE WITH ITS HEATING SOURCE TOWARDS THE OPERATING SIDE DIRECTION OR DRIVE SIDE DIRECTION TO LIQUIDATE ANY CATENARY SAG OF THE STRIP INSIDE THE OVEN PRESENTING THE STRIP SURFACE TO RECEIVE THE OPTIMUM RADIATION HEAT FROM SOURCE BOTH TOP AND BOTTOM SURFACE OF STRIP SURFACE INCLUDING STRIP EDGES TO ACHIEVE UNIFORMITY OF RADIATION HEAT FOR ALLOWING THE REQUIRED PMT IN TWO TO THREE SECONDS COMMENSURATE WITH THE HIGH SPEED OF THE LINE WITHOUT ANY LIMIT TO THE STRIP PROPELLING SPEED AND MORE SIGNIFICANTLY THE NEED OF ONLY NORMAL APPLICATION OF PRESSURE OF APPLICATOR ROLLS ON TO THE STRIP AT HIGH STRIP PROCESS SPEEDS TO LOW PROCESS SPEED RANGE PER SE NO LIMITATION ON LINE SPEED HITHERTO NOT ACHIEVED. (III)FINALLY, YET ANOTHER OBJECT IS THE APPLICATION OF JUDICIOUS MIXING OF HEAVY THINNERS IN PROPER RATIO TO THE NIR FORMULATED PAINTS TO PROVIDE THE BEST QUALITY OF COATED SURFACE AT TOP SPEED WITH SHORT CURING TIMES IN THE RANGE OF 1.5 TO 3.0 SECONDS TO AVOID CRACKING, EDGE BLISTERS, SURFACE ROUGHNESS ETC.