Production process of high-gloss TSPCC steel barrel body coil for environmental protection

Abstract

The application discloses a production process of a high-gloss TSPCC steel barrel body coil for environmental protection, breaks the previous cold-rolled commodity coil whole-process technology, and is characterized in that the process comprises the following steps: two steel smelting, hot rolling, acid continuous rolling, cold rolling cover annealing, cold rolling flattening, recoiling, and color coating, so that the cold-rolled commodity coil performance is ensured, and the color-coated commodity coil has rust prevention capability. According to the production process, the commodity coil is recoiled and straightened by using a cover furnace annealing device, a flattening unit and a recoiling device, and then is painted by using a color coating unit, so that the paint spraying process of a tomato paste barrel manufacturer is reduced, and the environmental protection pressure of a barrel manufacturing factory is also reduced.

Description

TECHNICAL FIELD

[0001] The application relates to a production process of a high-gloss TSPCC steel barrel body coil for environmental protection. BACKGROUND

[0002] At present, the planting area of tomatoes is continuously expanding, and the steel for tomato paste barrels reaches more than 50,000 tons per year. With the continuous improvement, perfection and rapid promotion of environmental protection regulations in China, barrel manufacturing companies begin to put forward new material requirements to steel plants, requiring not only the performance of cold-rolled commodity coils but also the good rust-proof function of color-coated coils, ensuring that the steel barrels have sufficient strength and the paint has good adhesion, so that the steel coil does not drop paint and does not rust during the processing. The barrel body material is a product newly developed by Bayi Steel Company in 2023. The following problems occur during the development: the steel coil has a light scratch defect on the lower surface during production, the scratch defect part appears a coating defect during color coating production, especially the head and tail, the cutting amount is large, and the color coating yield is less than 90%; the surface gloss of the steel coil is insufficient, and it is required to reach more than 70%, even if the special coating phthalo blue paint actually only has 55-60%; the performance of the steel coil is unstable during performance testing, and it is required to have a yield strength of 220-290 Mpa, and actual testing shows that some are less than 220 Mpa, and further repair treatment is required, otherwise the performance cannot meet the delivery requirements; the steel coil of this specification is prone to bonding mark defects, and the defect part appears uneven coating and coating defects during color coating; when used by the customer, the barrel body appears a crack during diameter expansion and a curved wave symptom during edge rolling, and cannot be edge rolled; when used by the customer, the barrel body appears a curved wave symptom during edge rolling, and cannot be edge rolled, resulting in scrap; when used by the customer, it is found that the finished barrel is not uniform in height, and the normal transportation is affected due to the use of stacking type transportation of oil drums during transportation.

[0003] Search literature: Research on diameter expansion cracking of cold-rolled barrel steel, Han Jiyan, Di Yanjun, Luo Xiaoyang, the welding seam diameter expansion cracking problem in the process of customer processing and use of cold-rolled barrel steel, and the microstructure and microstructure of the heat-affected zone and base material of the welding seam are compared and analyzed by metallographic microscope and SEM. The results show that the heat-affected zone has fine grain size, no obvious directionality, dense dislocation and shallow toughness, and the heat-affected zone shows brittle fracture morphology, and the base material shows plastic fracture morphology. By adjusting the welding parameters, reducing the welding current speed, increasing the welding time and reducing the post-weld cooling speed, the diameter expansion cracking of the welding seam is controlled to a certain extent, but cannot be completely eliminated. Further comparison of the composition control of barrel steel of other steel enterprises in the industry, comparison and analysis of carbon equivalent and cold crack sensitivity index, further optimization of the composition of the cold-rolled barrel steel of the steel plant, reduction of Mn content and increase of Si and Cr content. SUMMARY

[0004] The application discloses a production process of a high-gloss TSPCC steel barrel body coil for environmental protection, solves the problems of paint adhesion and gloss, solves the problem of low yield strength, and solves the problem of how to rescue the steel coil for continuous processing without uneven coating and coating defects.

[0005] The technical scheme of the method is as follows:

[0006] 1-4# tank hydrochloric acid temperature is controlled to 65-75 DEG C, and the process section running speed is controlled to 60-130 m / min;

[0007] The pickling unit is replaced with new acid 60-80 m 3 4 hours in advance before producing special steel, so that the HCL content of the acid liquid in the 1# acid tank is greater than or equal to 50 g / L, the iron ion content is less than or equal to 100 g / L, and the phenomenon of insufficient pickling is avoided;

[0008] The water outlet temperature of the 1# rinsing tank filter is 60-80 DEG C, the water conductivity of the 2# rinsing tank is less than or equal to 100 us / cm, and the opening degree of the water supply valve of the 2# rinsing tank is increased by 25%-40% compared with that of the ordinary steel;

[0009] When the steel coil is cut on the recoiling unit, the target width is 1027 mm, the precision is controlled to 0-2 mm, and the cutting defect is strictly prohibited;

[0010] In addition to the conventional parameter control, the residual emulsion on the surface of the strip steel is mainly controlled, and the annealing of the bell-type furnace unit is fully prepared;

[0011] The plate shape of the rolling mill unit is controlled according to the micro double edge wave, and the middle wave is strictly prohibited; the A2 control coefficient of the standard control curve of the plate shape instrument is set to +2, and the width is 930-1250 mm, all of which are suitable;

[0012] Before production, it is ensured that the blowing device of the last rolling mill is normal, the residual emulsion on the surface of the strip steel is not allowed, the blowing pressure of the rolling mill outlet is greater than 0.6 MPa, the nozzle is not allowed to be missing or blocked, the condensate water of the rolling mill outlet portal cannot drop on the surface of the strip steel, the residual oil amount on the surface of the strip steel is less than or equal to 300 mg / m 2 , and the residual iron amount on the surface of the strip steel is less than or equal to 120 mg / m 2 ;

[0013] After the rolling mill unit starts rolling production, the reflectivity of the steel coil surface is measured, the steel grade is strictly prohibited if the reflectivity is less than 50%, the normal scheme is executed if the reflectivity is greater than 60%, and the cover type furnace is immediately notified to enter the production rescue plan if the reflectivity is less than 50%-60%, namely, the temperature curve is increased by 430 DEG C platform for 3-4 hours, and the hydrogen blowing amount is increased from 25 m 3 / h to 30 m3 / h, hydrogen blowing time is extended for 3 hours;

[0014] The loading quantity of the steel grade shall not be less than 45 tons; when the loading quantity is 45-55 tons, the temperature is controlled at 690℃, the heating time is 8h, the holding time is ≥7h, the waiting time is 2h, and the discharge temperature is 95℃; when the loading quantity is 55-75 tons, the temperature is controlled at 690℃, the heating time is 9h, the holding time is ≥8h, the waiting time is 3h, and the discharge temperature is 100℃; when the loading quantity is >75 tons, the temperature is controlled at 690℃, the heating time is 10h, the holding time is ≥9h, the waiting time is 5h, and the discharge temperature shall be 100℃, and the heating cover temperature shall be lower than 600℃;

[0015] When the steel coil is discharged and cooled on the final cooling platform, the cooling temperature reaches 45℃, the cooling is stopped, and the outdoor suction port is closed in case of rainy days;

[0016] The temperature of the steel coil before the leveling production is consistent with the ambient temperature;

[0017] The roughness of the entry and exit tension rolls of the leveling unit shall reach 4.5±1.0μm;

[0018] The leveling unit adopts the roughened roll production, the roughness of the new work roll surface is controlled to 1.0±0.1μm, and the strip surface roughness is controlled to 0.6-0.7μm;

[0019] The liquid concentration of the leveling unit is controlled to 4.0%-6.0%, the production is carried out in the micro-medium wave mode, and the edge wave is strictly prohibited, and the wave shape station is located at the side of the coiler;

[0020] The blowing jet pressure of the leveling is >0.5MPA, and the blowing angle is controlled to 45°-60°;

[0021] The elongation of the leveling unit is strictly controlled, the elongation is increased by 0.1%-0.2% than the target value, the barrel thickness is 0.65-0.75mm, and the elongation is increased to 0.9%-1.0% during production;

[0022] The rolling force during the tailing of the leveling unit is required to be controlled to 2000-2500kN;

[0023] The leveling liquid is uniformly and overlappedly sprayed to the roll gap, the lifting angle of the entry anti-wrinkle roll shall be kept in the direction of 190-200°, to ensure that the leveling liquid is uniformly applied on the strip surface, the two nozzles in the middle of the leveling liquid are replaced from ¢1.5mm to ¢2.0mm, to increase the leveling liquid flow;

[0024] The stretching and straightening process of the recoiling unit is increased, to solve the curved wave symptoms of the barrel during the edge winding, and to avoid the scrap problem due to the failure of edge winding;

[0025] The middle bonding line defect occurs during production, and the rolling force of 1500-1800 kN is adopted in the temper mill for one time of tempering;

[0026] The coating is adjusted to high molecular resin polyester topcoat during color coating;

[0027] The temperature of 60-75°C is adopted for the temperature of 1# and 2# alkali liquid spraying and hot water rinsing before the pretreatment of ordinary galvanized substrate before color coating, and the temperature is controlled to 70±3°C during the production of the steel;

[0028] The alkali point of 6-10 mg / L is adopted for the alkali spraying of ordinary zinc substrate before color coating, the alkali point of 1# alkali liquid spraying is controlled to 6-10 mg / L, the alkali point of 2# alkali liquid spraying is controlled to 9-11, and 10 m³ of overflow of the pretreatment liquid is ensured every shift to ensure that the carbon black of the original plate can be fully discharged, and the tank liquid of the degreasing section is replaced and the liquid is re-prepared during the production of 2000 t of TSPCC annealed plate;

[0029] The chromium point of the passivation liquid of the color coating machine is controlled to 21-25 mg / L, and the Cr content of the passivation film of the passivated plate is 15-30 mg / m 2 The chromium point of the passivation liquid of the color coating machine is controlled to 23-25 mg / L, and the Cr content of the passivation film of the passivated plate is 25-30 mg / m 2 The sampling is sent for inspection within one hour after the shift, and the sampling is sent for inspection once every 3 hours in the later period; the PMT plate temperature after the color coating oven is controlled to 70-80°C, and the temperature is detected once every 4 hours by using the temperature gun or temperature paper A / B, the color coating drying requirements are that the passivation film is wiped with paper without obvious yellow spots, the steel strip surface is not coated, the surface is without pockmarks, passivation spots, and thick edges, and the yellow edge of the edge part, the passivation liquid is replaced when more than 1000 tons of TSPCC is produced;

[0030] The pressure adjustment of the coating roll and the dipping roll of the color coating machine makes the current value between the two rolls to be 30-80%, the roll speed ratio and the roll pressure of the coating roll are as follows: back primer: coating roll: dipping roll=1.3:0.4, face coating front, coating roll:dipping roll=1.3:0.5; roll pressure: 1100 kN±100; face coating back, coating roll:dipping roll=1.6:0.6, roll pressure: 1000 kN±100;

[0031] The bristles on the brush roll of the color coating unit are checked before the production of the steel, and the brush roll height is adjusted, the working current of the brush roll is 10-20 A, and all the brush rolls are put into use; meanwhile, the clogging of the pretreatment alkali washing and rinsing nozzles is checked and confirmed, the nozzle angle is controlled to 45-60° to ensure that the carbon black on the surface of the steel coil can be fully washed;

[0032] The rotation of the 6# and 7# squeezing rolls at the end of the hot water rinsing of the color coating unit is flexible without jamming, and the roll surface is not delaminated, and the angle of the 1# air knife is controlled to 45-60°.

[0033] When the color coating unit produces this steel grade, the water quenching spray pipeline pressure is 0.05-0.4Mpa, and the water quenching plate temperature is ≤45℃;

[0034] The color coating unit checks the strip steel once per shift, and the inspection method is as follows: at the 5# deflection roller after the degreasing section, a large cloth is wound on a wooden rod, and a force of 20kg is applied for pressing, and the running plate surface is wiped for 6-8 seconds, and the white cloth should be free of wetting, no obvious oil stains and black ash;

[0035] The color coating unit has no damage, bulging and degumming phenomenon on the surface of the coating roll, and the gap between the upper and lower roll systems is adjusted to 2-10mm;

[0036] The color coating unit generally controls the addition amount of diluent at 5-15%;

[0037] The color coating unit has a stirring speed of 400-800r / min, a stirring time of 20-40 minutes, and a paint use temperature requirement of ≥0℃;

[0038] Coating method: 1 / 2, initial coating backside is used, light yellow primer is coated, and reverse coating method is used for fine coating to coat the upper and lower surfaces, film thickness and paint viscosity;

[0039] Backside primer: dry film 4±1µm; viscosity: 30±2 seconds, using epoxy light yellow primer;

[0040] Front side paint: dry film 4±1µm; viscosity: 35±2 seconds, using cold-based special coating paint for color coating phthalo blue face paint;

[0041] Backside paint: dry film 6-9µm; viscosity: 55±2 seconds, using cold-based special coating paint for color coating phthalo blue face paint; film thickness: front side paint film thickness ≥3μm, backside paint film thickness ≥6μm; film thickness is the average value of three points, and the fluctuation value of backside paint film thickness should not exceed 2μm;

[0042] Color coating curing oven baking process design:

[0043] ;

[0044] Initial coating PMT: 216-232℃; fine coating PMT: 216-232℃, checked and adjusted per roll;

[0045] The color coating unit focuses on controlling the cleaning effect of the leveling liquid in the pretreatment, and all the brush rollers are used;

[0046] The color difference of the finished product should be less than 1.2.

[0047] Through the design and manufacture of the production process of the color coated plate for the barrel body of the sauce barrel, the sauce barrel manufacturing factory omits the previous cleaning-phosphating treatment-coating spraying production process of the sauce barrel production line, reduces the discharge of hazardous waste, meets the requirements of national environmental protection, and currently the first pass rate of the steel grade is increased from less than 85% in the early stage to 99.2%, no quality complaints are received from the customers, the satisfaction degree is increased from 50% in the early stage to 100%, the steel coil is used well, and meets the use of various tomato sauce barrel factories. The method solves the problems of paint adhesion and gloss; solves the problem of low yield strength; solves the problem of how to rescue the steel coil for continuous processing without uneven coating and missing coating defects. The problem of missing coating caused by scratches on the small surface of the steel coil during production is solved, and the first inspection qualified rate of the finished coil is improved. The problem of gloss is solved, and the actual gloss is more than 80% by using a special coating phthalo blue face paint with appropriate, reasonable and scientific plate surface roughness. The problem of large cracks in the barrel body during the diameter expansion, causing scrap, is solved by solving the problems of poor edge cutting, edge cracking during rolling and damage to the end part during transportation. The problem of curve wave symptoms in the barrel body during edge rolling, which causes scrap, is solved by solving the problem of steel coil plate flatness; the problem of uneven height of the finished barrel is solved by solving the problem of steel coil width precision, which is caused by the stacking transportation of the oil drum during transportation, affecting the normal transportation. DETAILED DESCRIPTION

[0048] EMBODIMENT

[0049] 1-4# tank hydrochloric acid temperature control to (℃): 65-75℃, process section running speed control to 60-130m / min.

[0050] The pickling unit is replaced with new acid 60-80m 3 4 hours in advance before producing special steel, to ensure that the HCL content of the acid liquid in the 1# acid tank is ≥50g / L, the iron ion content is ≤100g / L, and the under-pickling phenomenon is eliminated.

[0051] The 1# rinsing tank filter outlet temperature is 60-80℃, the 2# rinsing tank rinsing water conductivity test value is ≤100us / cm, the opening degree of the rinsing water valve is increased by 25%-40% than that of ordinary steel, all the wringing rollers must be in good condition, the roller surface is not allowed to have serious wear, bonding, scratches, peeling, thermal damage defects, and the blocking phenomenon must not occur during operation, and the "water mark" defect must not exist at the outlet of the pickling dryer.

[0052] When the steel coil is cut on the recoiling unit, the target width is 1027mm, and the precision is controlled to 0-2mm, and the cutting defect is strictly prohibited.

[0053] In addition to the conventional parameters control, the main control of the rolling mill unit is the residual emulsion on the strip surface, and at the same time, it is fully prepared for the annealing of the bell-type furnace unit.

[0054] The plate shape of the rolling mill unit is controlled according to the micro double edge wave, and the middle wave is strictly prohibited. The standard control curve A2 control coefficient is set to +2 (all applicable for width 930 to 1250㎜).

[0055] Before production, it is ensured that the blowing device of the last mill is normal, and there is no residual emulsion on the surface of the strip. The blowing pressure at the outlet of the mill is greater than 0.6MPA. The nozzle is not allowed to be missing or blocked, and the condensate water at the outlet of the mill house should not drop on the surface of the strip. The residual oil amount on the surface of the strip (single side) is less than or equal to 300mg / m 2 The residual iron amount on the surface of the strip (single side) is less than or equal to 120mg / m 2 .

[0056] After the rolling mill unit starts rolling production and the steel coil is produced, the reflectivity of the steel coil surface is measured. If the reflectivity is less than 50%, the production of this steel grade is strictly prohibited. If the reflectivity is greater than 60%, the normal scheme is executed. If the reflectivity is less than 50%-60%, the bell-type furnace is immediately notified to enter the production remediation plan, that is, the temperature rising curve increases the 430℃ platform for 3-4 hours, the hydrogen blowing amount increases from 25m 3 / h to 30m 3 / h, and the hydrogen blowing time is extended by 3-4 hours

[0057] The loading amount of this steel grade into the furnace should not be less than 45 tons. For loading amount of 45-55 tons, the control temperature is 690℃, the heating time is 8h, the holding time is ≥7h, the waiting time is 2h, and the discharge temperature is 95℃. For loading amount of 55-75 tons, the control temperature is 690℃, the heating time is 9h, the holding time is ≥8h, the waiting time is 3h, and the discharge temperature is 100℃. For loading amount greater than 75 tons, the control temperature is 690℃, the heating time is 10h, the holding time is ≥9h, the waiting time is 5h, and the discharge temperature is 100℃. In addition, the heating cover temperature should be lower than 600℃.

[0058] When the steel coil is discharged from the furnace and cooled on the final cooling table, the cooling temperature reaches 45℃, the cooling is stopped, and when it rains, the outdoor suction port of the plant should be closed.

[0059] Before the leveling production, it is confirmed that the temperature of the steel coil is consistent with the ambient temperature.

[0060] The roughness of the entry and exit tension rolls of the leveling unit should reach 4.5±1.0μm.

[0061] The leveling unit adopts the rough roll production, the new work roll surface roughness is controlled to 1.0±0.1μm, and the strip surface roughness is controlled to 0.6-0.7μm.

[0062] The liquid concentration of the temper mill unit is controlled to 4.0% to 6.0%, and the production is carried out according to the micro-waves mode, and the edge waves are strictly prohibited, and the wave shape station is located at the side of the coiler.

[0063] The blowing air pressure of the tempering is greater than 0.5MPA, the blowing angle control value is 45° to 60°, and the edge part should not have residual temper liquid spots.

[0064] Before the flat production, the temper liquid nozzles are inspected, and the temper liquid nozzles in the middle part of the strip steel should not have the blocking phenomenon, when the production width of the steel coil is less than 1000mm, the upper roll edge part 2 nozzles can be blocked to prevent the temper liquid from leaking out of the roll gap at the edge of the strip steel and splashing on the strip steel surface.

[0065] The elongation of the temper mill unit is strictly controlled, and the elongation is increased by 0.1% to 0.2% compared with the target value, and the details are as follows:

[0066] The barrel thickness is 0.65 to 0.75mm, and the elongation is increased to 0.9% to 1.0% during production.

[0067] The rolling force of the temper mill unit when the tail is thrown is required to be controlled to 2000 to 2500KN.

[0068] The temper liquid is uniformly and overlappedly sprayed to the roll gap, the inlet anti-wrinkle roll lifting angle must be kept in the direction of 190 to 200°, to ensure that the temper liquid is uniformly applied on the surface of the strip steel, the middle 2 nozzles of the temper liquid are replaced from ¢1.5mm to ¢2.0mm, the temper liquid flow is increased, and after the steel coil production is completed, the surface black ash can be thoroughly washed clean.

[0069] The stretch straightening process of the recoiling unit is increased, the strip shape wave degree must be less than 0.2% (wave height / wave length*100), to solve the curved wave symptoms of the barrel when the edge is rolled, and the problem of scrap due to the failure of edge rolling.

[0070] During production, the middle sticking defect occurs, and the rolling force of 1500 to 1800KN is used in the temper mill unit for tempering once.

[0071] During the production of the color coating, the conventional color coating paint primer is an epoxy primer, the topcoat is a polyester topcoat, and the bottom surface topcoat is an epoxy backcoat or a modified epoxy backcoat. The present application adjusts the coating to a high molecular resin polyester topcoat to adapt to the production process of the barrel production line.

[0072] The temperature of the 1# and 2# alkali liquid spraying and hot water rinsing during the pretreatment of the ordinary galvanized substrate before the color coating is 60 to 75℃, and when the steel grade is produced, the temperature is controlled to 70±3℃.

[0073] The ordinary zinc base plate before color coating pretreatment The alkali spraying alkali point is 6-10 mg / L, when producing the steel, the alkali spraying alkali point is controlled to 1# alkali liquid spraying 6-10 mg / L, 2# alkali liquid spraying 9-11, at the same time, 10 m³ of pretreatment liquid is overflowed every shift, so as to ensure that the carbon black of the original plate can be fully discharged, when producing 2000 t of TSPCC annealed plate, the tank liquid of the degreasing section is replaced, and the liquid is reconfigured.

[0074] The ordinary zinc base plate before color coating The passivation liquid chromium point of the coating machine is controlled to 21-25 mg / L, and the Cr content of the passivation plate film is 15-30 mg / m 2 When producing the steel, the passivation liquid chromium point of the coating machine is controlled to 23-25 mg / L, and the Cr content of the passivation plate film is 25-30 mg / m 2 The sample is taken and detected within one hour after the shift, and the sample is taken and detected once every 3 hours in the later period; the PMT plate temperature after the coating oven is controlled to 70-80℃, and the temperature is detected once every 4 hours by using a temperature gun or temperature paper A / B, and the coating drying requirements are that the passivation film is wiped by paper without obvious yellow spots, the steel strip surface is not coated, the surface is without pockmarks, passivation spots, and yellow spots on the edge, and the edge is thick, when producing more than 1000 tons of TSPCC barrel plate, the passivation liquid is replaced.

[0075] The pressure adjustment of the coating roll and the dipping roll of the coating machine of the color coating unit makes the current value between the two rolls 30-80%. The roll speed ratio and the roll pressure of the coating roll are as follows:

[0076] The back primer: the coating roll:dipping roll=1.3:0.4.

[0077] The face coating front coating roll:dipping roll=1.3:0.5 roll pressure:1100KN±100

[0078] The face coating back coating roll:dipping roll=1.6:0.6 roll pressure:1000KN±100.

[0079] Before producing the steel, the bristles on the brush roll of the color coating unit are checked, and the brush roll height is adjusted, the working current of the brush roll is 10-20 A, and all the brush rolls are put into use; meanwhile, the clogging of the pretreatment alkali washing and rinsing nozzles is checked and confirmed, and the nozzle angle is controlled to 45-60°, so as to ensure that the carbon black on the surface of the steel coil can be fully washed.

[0080] The 6# and 7# squeezing rolls at the end of the hot water rinsing of the color coating unit rotate flexibly without jamming, and the roll surface is not delaminated, and the angle of the 1# air knife is controlled to 45-60°.

[0081] When producing the steel, the water quenching spraying pipeline pressure of the color coating unit is 0.05-0.4 Mpa, and the water quenching plate temperature is ≤45℃.

[0082] The color coating unit checks the strip steel once per shift. The inspection method is as follows: at the 5# deflection roller after the degreasing section, a large cloth is wrapped on a wooden stick, and a force of 20 kg is applied to press and wipe the running plate for 6-8 seconds. The white cloth should not be wet, and there should be no obvious oil stains, black ash, etc.

[0083] The coating roller surface of the color coating unit should be free of damage, bulging, and delamination, and the gap between the upper and lower roller systems should be adjusted to 2-10 mm.

[0084] The diluent addition amount of the color coating unit is generally controlled at 5-15%. The ratio may vary with the coating temperature and the original viscosity.

[0085] The stirrer speed of the color coating unit is 400-800 revolutions per minute, the stirring time is 20-40 minutes, and the coating temperature requirement is ≥0℃.

[0086] Coating method: 1 / 2, initial coating on the back, light yellow primer, and final coating on both surfaces, using reverse coating, film thickness, and coating viscosity.

[0087] Back primer: dry film 4±1µm; viscosity: 30±2 seconds, using light yellow epoxy primer

[0088] Front paint: dry film 4±1µm; viscosity: 35±2 seconds, using cold-based special coating paint for color coating

[0089] Back paint: dry film 6-9µm; viscosity: 55±2 seconds, using cold-based special coating paint for color coating

[0090] Color coating curing oven baking process design:

[0091] ;

[0092] Initial coating PMT: 216-232℃; final coating PMT: 216-232℃, checked and adjusted per coil

[0093] The color coating unit focuses on controlling the cleaning effect of the leveling liquid during pretreatment, and all brush rollers are in use.

[0094] The color difference of the finished product must be less than 1.2, otherwise the customer may produce color difference defects when treating the weld and re-coating the paint.

[0095] During the hoisting process of the steel coil, the crane clamps are protected, and a dedicated person is in command. The end of the steel coil must not be damaged, otherwise large cracks may occur when the barrel diameter expands.

Claims

1. A production process for high-gloss, environmentally friendly TSPCC steel barrel coils, characterized in that... Follow these steps in sequence Implementation: The hydrochloric acid temperature in tanks 1-4 is controlled at 65-75℃, and the operating speed of the process section is controlled at 60-130m / min. Before the pickling unit produces the aforementioned steel grade, replace the acid with 60-80 ml of fresh acid 4 hours in advance. 3 Ensure that the HCl content of the acid solution in acid tank #1 is ≥50g / L and the iron ion content is ≤100g / L, and prevent the occurrence of under-acid washing. The outlet temperature of the filter in the No. 1 rinsing tank is 60℃~80℃; the conductivity of the rinsing water in the No. 2 rinsing tank is ≤100us / cm; and the opening of the rinsing water supply valve is increased by 25%~40% compared to SPCC steel. When steel coils are trimmed on the rewinding unit, the target width is 1027mm, and the accuracy is controlled to 0-2mm. Defective trimming is strictly prohibited. In addition to conventional parameter control, the rolling mill also controls the residual emulsion on the strip surface, while making full preparations for annealing in the bell-type furnace unit. The shape of the rolling mill unit is controlled by micro double-sided wave, and medium waves are strictly prohibited. The standard control curve A2 control coefficient of the shape meter is set to +2, and it is applicable to widths from 930 to 1250 mm. Before production, ensure the last stand's purging device is functioning properly. No emulsion residue is allowed on the strip surface. The mill exit purging pressure must be >0.6 MPa. No nozzles must be missing or clogged. Condensate from the mill exit stand must not drip onto the strip surface. The residual oil content on a single side of the strip surface must be ≤300 mg / m². 2 The residual iron content on a single side of the strip surface is ≤120mg / m. 2 ; Once the rolling mill begins rolling production, the surface reflectivity of the steel coils is measured after production. If the reflectivity is below 50%, production of that steel grade is strictly prohibited. If the reflectivity is above 60%, the normal procedure applies. If the reflectivity is between 50% and 60%, the bell-type furnace is immediately notified to activate the production remedial plan, which involves increasing the temperature rise curve to a 430°C plateau for 3-4 hours and reducing the hydrogen blowing rate from 25m³ / h. 3 / h increased to 30m 3 / h, the hydrogen blowing time is extended by 3 hours accordingly; The minimum charge for this steel grade is 45 tons; for charge grades of 45-55 tons, the controlled temperature is 690℃, heating time is 8 hours, holding time is ≥7 hours, waiting time before hood is installed is 2 hours, and the tapping temperature is 95℃; for charge grades of 55-75 tons, the controlled temperature is 690℃, heating time is 9 hours, holding time is ≥8 hours, waiting time before hood is installed is 3 hours, and the tapping temperature is 100℃; for charge grades >75 tons, the controlled temperature is 690℃, heating time is 10 hours, holding time is ≥9 hours, waiting time before hood is installed is 5 hours, and the tapping temperature is 100℃, with the temperature after removing the heating hood below 600℃. When the steel coils are cooled on the final cooling platform after exiting the furnace, cooling is stopped after the cooling temperature reaches 45°C. On rainy days, the external air intake of the plant must be closed. Before leveling production, confirm that the temperature of the steel coil is consistent with the ambient temperature at the site. The surface roughness of the tension rollers at the inlet and outlet of the leveling unit must reach 4.5±1.0μm; The leveling unit uses roughening rollers for production. The surface roughness of the new work rollers is controlled to 1.0±0.1μm, and the surface roughness of the strip steel plate is controlled to 0.6-0.7μm. The leveling liquid concentration of the leveling unit should be controlled to 4.0% to 6.0%. During production, it should be carried out in a micro-medium wave mode. Edge waves are strictly prohibited. Wave shape observation should be carried out at the side of the coiler. The jet pressure for leveling and purging is >0.5 MPa, and the purging angle is controlled at 45° to 60°. The leveling unit strictly controls the elongation rate, increasing it by 0.1%-0.2% compared to the target value. For barrel thicknesses of 0.65-0.75 mm, the elongation rate increases to 0.9%-1.0% during production. The rolling force during the tail-off phase of the leveling unit must be controlled to 2000-2500kN; The leveling liquid is sprayed evenly and overlappingly onto the roll gap. The lifting angle of the inlet anti-wrinkle roller must be maintained at 190-200° to ensure that the leveling liquid is evenly applied to the surface of the strip. The two nozzles in the middle of the leveling liquid are replaced with φ2.0mm instead of φ1.5mm to increase the flow rate of the leveling liquid. Adding a stretching and straightening process to the rewinding unit solves the problem of wavy edges appearing on the barrel during edge rolling, preventing it from being rolled and resulting in scrap. If a central adhesion defect occurs during production, the surface should be leveled again using a rolling force of 1500-1800kN on the leveling unit. During color coating, the paint should be adjusted to a high-polymer resin polyester topcoat; During the pretreatment process for producing the aforementioned steel grades, the temperature of the No. 1 and No. 2 alkaline solution spraying and hot water rinsing is controlled at 70±3℃; the alkaline point of the No. 1 alkaline solution spraying is controlled at 6-10mg / L, and the alkaline point of the No. 2 alkaline solution spraying is controlled at 9-11mg / L, with an overflow of 10m³ per shift. 3 The pretreatment solution ensures that the carbon black from the original plate can be fully discharged. When producing 2000t of TSPCC annealed plates, the degreasing tank solution is replaced and the solution is prepared again. During the production of the aforementioned steel grades in color coating, the chromium concentration of the passivation solution in the chemical coating machine is controlled to be 23–25 mg / L, and the chromium content of the passivation film on the passivation plate is 25–30 mg / m³. 2 Samples should be taken and sent for testing within one hour of taking over the shift, and then every 3 hours thereafter. The temperature of the PMT board after the chemical coating oven should be controlled at 70-80℃, and tested every 4 hours with a temperature gun or temperature paper A / B. The requirements for chemical coating drying are: the passivation film should not have obvious yellow spots when wiped with paper, there should be no missed coating on the steel strip surface, no pitting or passivation spots on the surface, and no thick edges with yellow spots. When producing more than 1000 tons of TSPCC drum boards, the passivation solution should be replaced. The pressure adjustment of the coating roller and the feed roller of the color coating unit is adjusted so that the current value between the two rollers is 30-80%. The roller speed ratio and roller pressure are as follows: 1) Back primer: the roller speed ratio of the coating roller to the feed roller is 1.3:0.4; 2) Topcoat front: the roller speed ratio of the coating roller to the feed roller is 1.3:0.5, and the roller pressure is 1100kN±100; 3) Topcoat back: the roller speed ratio of the coating roller to the feed roller is 1.6:0.6, and the roller pressure is 1000kN±100. Before producing the steel grade, the color coating unit inspects the bristles on the brush rollers and adjusts the height of the brush rollers. The working current of the brush rollers is 10-20A, and all brush rollers are put into use. At the same time, the blockage of the pretreatment alkaline washing and rinsing nozzles is checked and confirmed. The nozzle angle is controlled to 45-60° to ensure that the carbon black on the surface of the steel coil can be fully cleaned. The No. 6 and No. 7 squeeze rollers at the end of the hot water rinsing of the color coating unit rotate flexibly without jamming and without degumming on the roller surface; the angle of the No. 1 air knife is controlled to 45-60°. When the color coating unit produces the aforementioned steel grades, the water quenching spray pipeline pressure is 0.05-0.4 MPa, and the water quenching plate temperature is ≤45℃; The color coating unit inspects the strip steel once per shift. The inspection method is as follows: at the No. 5 turning roller after the degreasing section, wrap a large cloth around a wooden stick, apply a pressure of 20 kg, and wipe the running plate surface for 6-8 seconds. Check that the white cloth is not wet and has no obvious oil stains or black dust. The coating rollers of the color coating unit are undamaged, without bulging or degumming. The gap between the material suction roller and the coating roller of the upper and lower roller systems is adjusted to 2-10mm. The amount of thinner added to the color coating unit should be controlled at 5-15%; The mixer speed of the color coating unit is 400-800 rpm, the mixing time is 20-40 minutes, and the coating application temperature requirement is ≥0℃. Coating method: 1 / 2, initial coating on the back side, apply light yellow primer, fine coating on both top and bottom surfaces, using a reverse coating method, coating thickness and paint viscosity: Back primer dry film thickness: 4±1μm; paint viscosity: 30±2 seconds, using epoxy light yellow primer; Dry film thickness of topcoat: 4±1μm; Coating viscosity: 35±2 seconds; Phthalocyanine blue topcoat is used as a special cold-based color coating coating. Backside paint dry film: 6-9μm; Paint viscosity: 55±2 seconds, using cold-based color coating special paint phthalocyanine blue topcoat, coating film thickness: front paint film thickness ≥3μm, back paint film thickness ≥6μm; film thickness is the average of three points, and the fluctuation value of the back paint film thickness shall not exceed 2μm; Color coating curing oven baking process design: Specifications thickness 0.6-0.8mm * 1025, primer oven hot air temperature (°C): Section 1 50-80°C, Section 2 50-80°C, Section 3 60-90°C, Section 4 40-70°C; Finishing coat oven hot air temperature (°C): Section 1 320-340°C, Section 2 370-390°C, Section 3 380-400°C, Section 4 360-380°C; In principle, the temperature from high to low should be in the following order: Section 3 - Section 2 - Section 4 - Section 1. This order should not be changed during operation. In actual control, the oven temperature should be adjusted promptly based on the temperature measuring paper. Initial coating PMT: 216-232℃; Finish coating PMT: 216-232℃. Check and adjust for each roll. The pretreatment process of the color coating unit focuses on controlling the cleaning effect of the leveling liquid, and all brush rollers of the unit must be put into use; the color difference of the finished product must be less than 1.2.