Process description
Workers use overhead cranes and other equipment to place the coil onto the saddle of the feeding trolley. The trolley lifts and transports the coil to the centerline of the work line and the unwinding machine drum. The unwinding machine drum is expanded by hydraulic pressure to tighten it with the inner diameter of the coil, and then the feeding trolley descends and returns to the storage position to prepare for the next coil operation.
The unwinding machine is closely attached to the outer diameter of the coil and has an adjustable buffer roller. When cutting the strapping, it is used to prevent the coil from suddenly releasing. The buffer roller can also assist in feeding the head of the coil into the front clamping machine, which provides the head of the coil to wait for riveting in front of the riveting machine.
The prepared strip is guided by the clamping machine and roller conveyor into the support position in front of the riveting machine until all the strips on the other unwinding machine are released. When the tail reaches the riveting position, the riveting machine will rivet the two rolls of strip together.
After the riveting machine, a flattening roller is installed to flatten the seam of the steel coil.
1 # Tensioner pulls the strip from the entrance end of the work line and imports it into the entrance loop.
The entrance loop roller is a chrome plated roller that is normally filled. When the entrance section is stopped during welding, it still supplies the strip to the cleaning roller coating process section that continues to operate. The entrance loop can supply approximately 260m of strip when the operating line is running at full speed. After each riveting cycle of the strip is completed and restarted, the entire inlet section will run at high speed until the inlet sleeve is filled with the strip, and then the inlet section will automatically slow down to the same speed as the cleaning roller coating process section. Repeat the next work cycle until the tape is fully released.
The entrance section is equipped with a main operation console, which has control buttons for the entrance section's main control equipment and an industrial computer.
The board enters the cleaning section from the inlet loop through the 2 # tensioner. The cleaning section has 2 soaking tanks, 2 external spray tanks, and 2 roller brushing machines. The first tank is a pre degreasing tank, which uses hot alkaline cleaning solution to spray and wash both sides of the strip. A roller brushing machine is installed in the middle to scrub the upper and lower surfaces of the steel plate and clean the main debris on the surface of the strip; The second tank is a degreasing tank, which uses a higher concentration of hot alkaline cleaning solution to spray and wash both sides of the strip, further removing oil stains on the surface of the steel plate, and is equipped with a roller brush machine; The third tank is a water washing tank, which uses hot water to rinse the strip to ensure that residual liquids such as degreaser on the surface are cleaned thoroughly. The fourth tank is also a hot water flushing tank, which further flushes away residual chemicals and other substances on the strip, and further removes the surface of the steel plate. The last tank uses pure water to clean the surface of the steel plate, replacing harmful ions in various chemical solutions on the surface. There is a horizontal spray circulation pump in each of the first to fourth tanks, with a certain number of nozzles installed in each section. A pair of squeezing rollers are installed at the outlet of each section and the inlet of the degreasing tank to squeeze out the solution on the surface of the board, preventing it from being carried into the next cleaning section and causing liquid leakage. The squeezing pressure of the squeezing rollers is adjusted by a cylinder.
After the cleaning section, the board passes through a water vapor drying device, and hot air is sprayed at high speed onto the strip to blow away the residual moisture on the strip, causing it to evaporate and dry.
After cleaning, the sheet enters the chemical coating roller coating machine, where a layer of chemical solution is applied to the upper and lower surfaces of the steel plate.
The chemical roller coating machine applies chemical conversion film on the surface of steel plates on both sides. Each roller coating device has two rollers, a feeding roller and a roller coating roller, and a clutch device driven by an oil cylinder.
After leaving the chemical roller coating machine, the strip is freely suspended and passed upward through the chemical coating drying furnace. The drying furnace is adjusted to the required heating process temperature, and the heat is supplied by the waste heat of the incinerator, which is heated by the hot air circulation of its own fan.
After leaving the furnace, the strip is cooled and directed through the centering device before entering the 3 # tensioner and being sent to the primer roller coating machine. The reverse side of the roller coating machine is coated with the same type of coating on the surface of the strip. The coating is taken out from the paint tray by the feeding roller, and the paint tray has a lifting function (manual worm gear lifting). The coating is rotated and applied to the roller coating roller, and then applied to the strip by the roller coating roller. The roller coating roller can rotate in the opposite direction of the strip running (reverse coating) or rotate in the same direction as the strip running (same direction coating). Both sets of coating heads on the reverse side have clutch devices driven by hydraulic cylinders, which can be opened synchronously when the joints pass through.
For the convenience of installation and replacement, all coating rollers are symmetrically designed, and the roller necks can be interchanged with each other, and can also be interchanged between different roller coating machines. The roller neck is installed on the self positioning chuck bearing, and for quick disassembly, the bearing is installed on the joint cover. Each roller of each roller coating machine platform can be driven forward/reverse by a frequency conversion motor through a sealed reducer, allowing for forward or reverse roller coating.
After leaving the roller coating machine, the strip passes through the paint curing furnace in a freely hanging form. The solvent is heated and evaporated by the heat in the curing furnace, and the strip is heated to a predetermined temperature to cure the coating. The temperature inside the furnace is controlled in four stages, equipped with a natural gas premixed large adjustment ratio combustion machine, which relies on waste heat from waste gas incineration for centralized heating. There are four stages of hot air circulation, and a temperature measurement and control system is equipped on the gas pipeline of the paint curing furnace to control the excess oxygen content in the flue gas to control the amount of oxygen required for cracking and supplement air.
After the strip leaves the curing furnace, it is cooled separately with water, squeezed dry, and aligned by the 2 # correction machine to ensure that the sheet runs in the middle of the rollers.
The strip is first coated, cured, baked, cooled, and then directed towards the centering device before entering the 4 # tensioner.
4 # Tensioner is a speed roller that controls the overall line speed.
After turning to the centering device, the strip passes through the precision coating machine and curing baking before entering the water cooling system. After being squeezed dry, it enters the centering device of the 4 # correction machine and then enters the 5 # tensioner.
The export sleeve roller is a chrome plated roller, which is empty during normal operation. When unloading or dividing at the exit section, the exit loop stores the strip that continues to come from the roller coating process section. After the next roll starts to be coiled, the exit section speeds up and empties the loop to ensure continuous operation of the process section.
Install an inspection section after the loop, which allows for easy observation of the surface quality of the strip coating.
Behind the export loop is the 6 # tensioning device, which maintains the appropriate tension in the export loop and provides rear tension for the winding machine. A protective film laminating machine is reserved in front of the tensioning device. There is an electric shearing machine between the clamping rollers to cut off the riveted or sewn joints of the strip or divide it into the required roll weight, and at the same time cut out a finished steel strip for inspection and testing.
There is a photoelectric edge control device between the winding machine and the pinch roller, and the sensor can detect the edge of the strip. If the strip deviates laterally, it sends a signal to the winding machine to follow and ensure uniform edge winding.
When the required diameter of the coil is reached, the winding machine stops. Before the winding machine stops, the unloading trolley stops under the coil of the winding machine. After the strip is cut, the unloading trolley rises to support the steel coil and moves to detach from the spindle. Then, the coil is sent to the outlet saddle for bundling and weighing.
After the head of the next strip is fed into the winding machine, it is wound several times with auxiliary winding, and the strip is tensioned. The winding machine accelerates until the strip in the loop is empty, and the outlet section returns to the speed of the process section and runs continuously
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