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What is the continuous casting and rolling process of the packaged steel strip and thin slab?
by：Hongmei
2021-03-15
What is the continuous casting and rolling process of packaged steel strip and thin slab?
Answer: The thin slab continuous casting and rolling process is mainly composed of four parts: continuous casting, soaking, continuous rolling and flat coiling. Each part of the process is specifically introduced as follows:
(1) Continuous casting process. The refining straddle crane hoists the ladle containing the refined molten steel on the rotary arm of the ladle turret, the manipulator on the top of the rotary table covers the ladle on the ladle, and then the rotary arm is raised and rotated 180° to transfer the ladle to the continuous casting span Above the mold, connect the long nozzle, open the ladle sliding nozzle and pour the molten steel into the baked tundish. When the molten steel in the tundish rises to a predetermined height, turn on the tundish stopper and inject molten steel into the mold as required. After the molten steel in the mold is higher than the immersion nozzle steel outlet for a certain height, add protective slag to the molten steel. Then the mold vibrating device and pinch roll are automatically turned on to draw the billet. At the same time, the secondary cooling water main valve of the fan-shaped section opens to spray water for cooling, and the crystallizer liquid level detection control system and tracking system are put into operation. When the slab head enters the sector II section from the sector I, the tracking system sends out a signal, and the arc side of the sector I implements liquid core reduction to press the slab from 50-70mm to 45-50mm. The slab head passes through the sector. The 3 sections continue vertically downwards and pass through the top bending roller. The top-bending roll action will top-bend the head of the casting slab, so that the ingot bar is separated from the casting slab. Then the top bending roll further top-bends the casting billet head to a circular arc line with a radius of 3.25m, and the cast billet enters the straightening machine along the bending radius under the guidance of the bending roll and the arc guide section. The straightened billet advances in the horizontal direction. After the billet head passes the pendulum shear, the pendulum shear action cuts the billet head, the cut head falls into the cutting head box, and the billet continues to enter the soaking furnace.
(2) Soaking process of roller hearth furnace. The straight-through roller hearth furnace has the functions of heating, soaking, heat preservation and buffering. When the continuous casting slab cast by the continuous casting machine enters the roller hearth furnace at the casting speed and after the tail of the slab completely passes through the heating section, it starts to accelerate to the maximum speed of 65m/min, and enters the holding section and subsequent sections through the conveying section and the ferry section. The slab is stretched apart to ensure the necessary buffer time. Then the heated cast slab leaves the soaking furnace at the biting speed of the first stand of the rolling mill, and enters the rolling mill for rolling. When the slab from the second casting machine enters the No. 2 furnace at the casting speed and the tail of the slab passes through the heating section of the furnace, the slab starts to accelerate and also passes through the conveying section at the maximum speed until the ferry section at the end of the furnace. After the ferry section of the two furnaces is rotated and restored, the slab advances to the holding section of the No. 1 furnace and enters the rolling mill at the rolling speed for rolling. The slab furnace temperature is 850-1050℃, and the slab discharge temperature is 1100-1150℃. It is optimized by the computer system to ensure that the target temperature accuracy of the slab discharge along the length and thickness directions reaches the requirement of ±10℃.
(3) Continuous rolling process. After the cast slab is released from the furnace, the conveying roller table will send the thin slab to the high-pressure water descaling device through the accident, and use high-pressure water to remove the oxide scale and residual mold slag, and then enter the finishing mill to roll to the thickness of the finished product. Handan Iron and Steel has set up an irreversible rough rolling mill to roll the slab to 35mm thick and send it to a finishing rolling mill because of the thick cast slab.
In order to ensure the precision of strip steel, control the shape and flatness, each stand of finishing rolling is equipped with CVC system, WRB system, AGC system, PCFC system, quick roll changing device and measuring instrument. The laminar cooling device cools the strip steel to the coiling temperature according to the corresponding final rolling temperature according to the corresponding final rolling temperature according to different steel grades and specifications. The strip enters the three-roller undercoiler and is rolled into a steel coil with a certain diameter. The unloading trolley removes the steel coils and transfers them to the steel coil lifting car, and then rotates to the No. 1 walking beam and No. 2 walking beam, which are inspected, weighed, bundled, and printed at the strip inspection station. . Then, the steel coil is transported to the steel coil storage or sent to the finishing span for levelling and sub-coiling.
(4) Flattening and sub-rolling process. The steel coil is transported to the steel coil preparation station by crane, the strapping is removed, the head is cut, the steel coil is transported to the uncoiler by the loading trolley, and then sent to the straightening machine and leveling machine by the pinch roller. The flattened steel strip is then divided and sheared separately. The flattened and split steel strip is then rolled into a steel coil by a coiler. Then, the steel coil is unloaded from the coiler by the steel coil trolley and sent to the walking beam conveyor for weighing, bundling, and printing. Finally, the crane unloads the steel coils to the finished product warehouse for delivery.
Answer: The thin slab continuous casting and rolling process is mainly composed of four parts: continuous casting, soaking, continuous rolling and flat coiling. Each part of the process is specifically introduced as follows:
(1) Continuous casting process. The refining straddle crane hoists the ladle containing the refined molten steel on the rotary arm of the ladle turret, the manipulator on the top of the rotary table covers the ladle on the ladle, and then the rotary arm is raised and rotated 180° to transfer the ladle to the continuous casting span Above the mold, connect the long nozzle, open the ladle sliding nozzle and pour the molten steel into the baked tundish. When the molten steel in the tundish rises to a predetermined height, turn on the tundish stopper and inject molten steel into the mold as required. After the molten steel in the mold is higher than the immersion nozzle steel outlet for a certain height, add protective slag to the molten steel. Then the mold vibrating device and pinch roll are automatically turned on to draw the billet. At the same time, the secondary cooling water main valve of the fan-shaped section opens to spray water for cooling, and the crystallizer liquid level detection control system and tracking system are put into operation. When the slab head enters the sector II section from the sector I, the tracking system sends out a signal, and the arc side of the sector I implements liquid core reduction to press the slab from 50-70mm to 45-50mm. The slab head passes through the sector. The 3 sections continue vertically downwards and pass through the top bending roller. The top-bending roll action will top-bend the head of the casting slab, so that the ingot bar is separated from the casting slab. Then the top bending roll further top-bends the casting billet head to a circular arc line with a radius of 3.25m, and the cast billet enters the straightening machine along the bending radius under the guidance of the bending roll and the arc guide section. The straightened billet advances in the horizontal direction. After the billet head passes the pendulum shear, the pendulum shear action cuts the billet head, the cut head falls into the cutting head box, and the billet continues to enter the soaking furnace.
(2) Soaking process of roller hearth furnace. The straight-through roller hearth furnace has the functions of heating, soaking, heat preservation and buffering. When the continuous casting slab cast by the continuous casting machine enters the roller hearth furnace at the casting speed and after the tail of the slab completely passes through the heating section, it starts to accelerate to the maximum speed of 65m/min, and enters the holding section and subsequent sections through the conveying section and the ferry section. The slab is stretched apart to ensure the necessary buffer time. Then the heated cast slab leaves the soaking furnace at the biting speed of the first stand of the rolling mill, and enters the rolling mill for rolling. When the slab from the second casting machine enters the No. 2 furnace at the casting speed and the tail of the slab passes through the heating section of the furnace, the slab starts to accelerate and also passes through the conveying section at the maximum speed until the ferry section at the end of the furnace. After the ferry section of the two furnaces is rotated and restored, the slab advances to the holding section of the No. 1 furnace and enters the rolling mill at the rolling speed for rolling. The slab furnace temperature is 850-1050℃, and the slab discharge temperature is 1100-1150℃. It is optimized by the computer system to ensure that the target temperature accuracy of the slab discharge along the length and thickness directions reaches the requirement of ±10℃.
(3) Continuous rolling process. After the cast slab is released from the furnace, the conveying roller table will send the thin slab to the high-pressure water descaling device through the accident, and use high-pressure water to remove the oxide scale and residual mold slag, and then enter the finishing mill to roll to the thickness of the finished product. Handan Iron and Steel has set up an irreversible rough rolling mill to roll the slab to 35mm thick and send it to a finishing rolling mill because of the thick cast slab.
In order to ensure the precision of strip steel, control the shape and flatness, each stand of finishing rolling is equipped with CVC system, WRB system, AGC system, PCFC system, quick roll changing device and measuring instrument. The laminar cooling device cools the strip steel to the coiling temperature according to the corresponding final rolling temperature according to the corresponding final rolling temperature according to different steel grades and specifications. The strip enters the three-roller undercoiler and is rolled into a steel coil with a certain diameter. The unloading trolley removes the steel coils and transfers them to the steel coil lifting car, and then rotates to the No. 1 walking beam and No. 2 walking beam, which are inspected, weighed, bundled, and printed at the strip inspection station. . Then, the steel coil is transported to the steel coil storage or sent to the finishing span for levelling and sub-coiling.
(4) Flattening and sub-rolling process. The steel coil is transported to the steel coil preparation station by crane, the strapping is removed, the head is cut, the steel coil is transported to the uncoiler by the loading trolley, and then sent to the straightening machine and leveling machine by the pinch roller. The flattened steel strip is then divided and sheared separately. The flattened and split steel strip is then rolled into a steel coil by a coiler. Then, the steel coil is unloaded from the coiler by the steel coil trolley and sent to the walking beam conveyor for weighing, bundling, and printing. Finally, the crane unloads the steel coils to the finished product warehouse for delivery.
