Continuous pickling galvanized flat steel production line and production process thereof

Abstract

The invention relates to a continuous pickling galvanized flat steel production line and a production process thereof, and belongs to the technical field of galvanized flat steel production in the metallurgical industry. According to the technical scheme, the production line comprises an uncoiler (1), a straight head machine (2), a hydraulic shear (3), a welding machine (4), a horizontal loop (5), a scale breaker (6), a pickling tank (7), a rinsing tank (8), a hot air drying box (9), a longitudinal cutting shear (10), a heating furnace (11), a zinc pot (12), a movable air box (13), a cooling air box (14), a water cooling tank (15), a finished product straightening machine (16), a passivation tank (17), a passivation drying box (18), a fixed-length shear (19) and a stacker crane (20) which are sequentially arranged. The unbender (2) is of an integral structure composed of a pinch roll and a strip steel straightening machine. The pickling unit, the galvanizing unit and the cutting unit are highly integrated into one unit, the production efficiency is greatly improved, meanwhile, technological parameters are optimized, and the product quality is improved.

Description

Technical Field

[0001] The invention relates to a continuous pickling galvanized flat steel production line and a production process thereof, belonging to the technical field of galvanized flat steel production in the metallurgical industry. Background Art

[0002] At present, there are two main production methods for galvanized flat steel. The first is to cut hot-rolled flat steel or hot-rolled strip steel to a certain length, and then enter the zinc pot for galvanizing after immersion pickling, water washing, and auxiliary plating. This is a non-continuous production process with low operating efficiency, and the plating agent is not environmentally friendly. The second is to use hot-rolled strip steel, clean the iron oxide scale with a pickling unit, produce galvanized coils with a galvanizing unit, and then cut to a certain length with a shearing unit to become galvanized flat steel. This is a process of plating first and then cutting. The end cut of the flat steel has no zinc layer protection, poor corrosion resistance, and a short product life.

[0003] Therefore, it is extremely important to design a galvanized flat steel production line and its production process with high operating efficiency, low energy consumption and environmental friendliness in the production of galvanized flat steel finished products. Summary of the invention

[0004] The purpose of the present invention is to provide a continuous pickling galvanized flat steel production line and its production process, which highly integrates the pickling unit, galvanizing unit and cutting unit into one unit, reduces energy consumption, greatly improves production efficiency, optimizes process parameters, improves product quality, and solves the problems existing in the background technology.

[0005] The technical solution of the present invention is: A continuous pickling galvanized flat steel production line comprises an uncoiler, a straightening machine, a hydraulic shear, a welding machine, a horizontal looper, a scale breaker, a pickling tank, a rinsing tank, a hot air drying box, a slitting shear, a heating furnace, a zinc pot, a mobile bellows, a cooling bellows, a water cooling tank, a straightening machine, a passivation tank, a passivation drying box, a cut-to-length shear and a stacker which are arranged in sequence.

[0006] Furthermore, the straightening machine is an integral structure composed of a pinch roller and a strip straightening machine, and the straightening machine cooperates with the uncoiler.

[0007] Furthermore, the pinch rollers in the straightening machine include straightening pinch upper rollers and straightening pinch lower rollers, the straightening pinch upper rollers and the straightening pinch lower rollers are installed on the frame of the strip straightening machine, the straightening pinch lower rollers and the lower straightening roller group are on the same horizontal plane, the outlet of the pinch rollers cooperates with the inlet of the strip straightening machine, and the inlet of the pinch rollers cooperates with the uncoiler.

[0008] Furthermore, there are two uncoilers, one for use and one for backup.

[0009] A continuous pickling galvanized flat steel production process adopts the above-mentioned continuous pickling galvanized flat steel production line and operates according to the following steps: a. The hot-rolled strip is uncoiled by the uncoiler, and then straightened by the straightening machine. The unqualified part of the strip head is cut off by hydraulic shears, and then sent to the welding machine for preparation and waiting for welding; b. When the production of the running strip steel is completed, the tail of the strip steel will be separated from the coiler and enter the straightening machine for straightening. The unqualified part of the tail of the strip steel will be cut off by hydraulic shears, and the tail will be sent to the welding machine. The head of the waiting steel coil will be sent to the welding machine, and the two coils of strip steel will be welded together to ensure the continuous operation of the production line; c. When the strip is being tail-flipped or welded, the horizontal looper enters the release procedure, so that the back-end process can still be in production while the front-end process is stopped; d. After welding is completed, the uncoiler resumes operation, and the production speed exceeds the rear-end production speed to achieve the purpose of punching the horizontal looper; the other uncoiler performs coiling and preparation work; e. After the strip arrives at the descaling machine, it is repeatedly bent and stretched to break the iron oxide scale on the surface of the hot-rolled strip, and part of the iron oxide scale falls off; f. The strip is cleaned of iron oxide in the pickling tank, and the residual acid is rinsed in the rinsing tank. The surface moisture of the strip is dried in the hot air drying box, and then it enters the longitudinal cutting shearing strip; g. The slitting shear sets the number and width of strips according to the production process requirements. After the strips are slitting, they enter the heating furnace for heating; then they enter the zinc pot for galvanizing; h. After the flat steel leaves the zinc pot, it is cooled by moving bellows and cooling bellows, and then enters the water cooling tank for final cooling; i. After the flat steel is cooled to the target temperature, it enters the straightening machine for straightening, then enters the passivation tank for passivation, and is dried in the passivation drying box; j. After drying, the flat steel is cut to the target length and then stacked and packaged.

[0010] In the above-mentioned continuous pickling galvanized flat steel production process, the acid production temperature in the pickling tank is 60℃-85℃, the acid circulation volume is 500-800L / min, and the acid concentration is 60-180g / L; the rinsing water temperature in the rinsing tank is 45℃-60℃, and the conductivity is controlled below 80μS / cm; the temperature of the hot air drying box is controlled at 90℃-105℃; the circulating air volume is 6000-12000m³ / h; the heating furnace adopts electromagnetic induction heating, the electromagnetic induction heater has a rated power of 650kW, the maximum heating temperature is 550℃, and a nitrogen-hydrogen mixed protective gas is used in the furnace, the hydrogen content is 5%-15%, the furnace pressure is 50-150Pa, the oxygen content is less than 80ppm, and the dew point is less than -20℃; the zinc liquid temperature in the zinc pot is 450℃-480℃; the drying circulating air temperature of the passivation drying box is 120℃-180℃.

[0011] The beneficial effects of the present invention are: the pickling unit, the galvanizing unit and the cutting unit are highly integrated into one unit, which reduces energy consumption, greatly improves production efficiency, optimizes process parameters and improves product quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is the plan layout diagram of the production line of the present invention; Figure 2 This is a schematic diagram of the structure of the straightening machine of the present invention; In the figure: 1. Uncoiler, 2. Straightening machine, 3. Hydraulic shears, 4. Welding machine, 5. Horizontal looper, 6. Descaling machine, 7. Pickling tank, 8. Rinsing tank, 9. Hot air drying box, 10. Slitting shears, 11. Heating furnace, 12. Zinc pot, 13. Mobile bellows, 14. Cooling bellows, 15. Water cooling tank, 16. Straightening machine, 17. Passivation tank, 18. Passivation drying box, 19. Cut-to-length shears, 20. Palletizer.

[0013] 21. Steel coil on uncoiler, 22. Uncoiler swing cylinder, 23. Uncoiler swing guide, 24. Uncoiler telescopic guide, 25. Straightening pinch roller lifting cylinder, 26. Straightening pinch roller upper roller, 27. Straightening pinch roller lower roller, 28. Straightening roller group fast lifting cylinder, 29. Upper straightening roller group, 30. Lower straightening roller group, 31. Straightening roller group fine-tuner. DETAILED DESCRIPTION

[0014] The present invention will be further described below by way of examples with reference to the accompanying drawings.

[0015] See attached Figure 1-2 A continuous pickling galvanized flat steel production line comprises an uncoiler 1, a straightening machine 2, a hydraulic shear 3, a welding machine 4, a horizontal looper 5, a scale breaker 6, a pickling tank 7, a rinsing tank 8, a hot air drying box 9, a slitting shear 10, a heating furnace 11, a zinc pot 12, a mobile bellows 13, a cooling bellows 14, a water cooling tank 15, a straightener 16, a passivation tank 17, a passivation drying box 18, a cut-to-length shear 19 and a palletizer 20 which are arranged in sequence.

[0016] In this example, refer to the attached Figure 1 The hot rolled strip is uncoiled by the uncoiler 1, and enters the straightening machine 2 to straighten the strip head. The unqualified part of the strip head is cut off by the hydraulic shear 3, and sent to the welding machine 4 for preparation and waiting for welding.

[0017] When the production of the running strip steel is completed, the tail of the strip steel is separated from the coiler 1 and enters the straightening machine for straightening. The unqualified part of the strip steel tail is cut off by the hydraulic shear 3 and the tail is swung to the welding machine 4. The head of the waiting steel coil is sent to the welding machine 4, and the two coils of strip steel are welded together to ensure the continuous operation of the production line.

[0018] When the strip is being tail-swept and welded, the horizontal looper 5 enters the looping procedure, so that when the front-end process is stopped, the back-end process can still be produced and run.

[0019] After welding is completed, the uncoiler 1 resumes operation, and the production speed exceeds the rear end production speed, so as to achieve the purpose of punching the horizontal looper 5. The other uncoiler 1 performs coiling and preparation work.

[0020] After the strip reaches the scale breaker 6, it is repeatedly bent and stretched to break the iron oxide scale on the surface of the hot-rolled strip, and part of the iron oxide scale falls off, thereby improving the subsequent pickling efficiency.

[0021] The strip is cleaned of iron oxide scale in the pickling tank 7, rinsed clean with residual acid in the rinsing tank 8, dried with hot air drying box 9, and then enters the longitudinal cutting shear 10 for stripping.

[0022] The slitting shear 10 sets the number and width of strips according to the production process requirements. After the strips are slitting, they enter the heating furnace 11 for heating. The furnace atmosphere adopts the electric radiation tube heating mode, and the flat steel strips are heated to the target temperature by the electromagnetic induction heating mode, and then enter the zinc pot 12 for galvanizing.

[0023] The zinc pot 12 is equipped with a sinking roller, a stabilizing roller and an air knife, and the thickness of the zinc layer is controlled by the air knife to ensure the uniformity and thickness accuracy of the zinc layer of the product.

[0024] After the flat steel leaves the zinc pot, it is cooled by the moving bellows 13 and the cooling bellows 14, and then enters the water cooling tank 15 for final cooling to reach the target temperature.

[0025] After the flat steel is cooled to the target temperature, it enters the straightening machine 16 for straightening, then enters the passivation tank 17 for passivation, and is dried in the passivation drying box 18 to improve the corrosion resistance of the product.

[0026] The flat steel is finally cut to the target length by the cut-to-length shear 19, and is stacked and packaged by the stacking machine 20, completing the whole set of processing procedures for the flat steel product.

[0027] The specific process requirements are as follows: Uncoiler 1, two units in total, can receive coils with inner diameters ranging from 580-620mm, outer diameters ranging from 750-1900mm, widths ranging from 200-600mm, and weights ranging from 1.5 to 10 tons. It can provide a maximum tension of 5000kN.

[0028] Straight head machine 2 as attached Figure 2As shown, the pinch rollers in the straightening machine 2 include an upper straightening pinch roller 26 and a lower straightening pinch roller 27, which are installed on the frame of the strip straightening machine, and the lower straightening pinch roller 27 and the lower straightening roller group 30 are on the same horizontal plane, and the outlet of the pinch rollers matches the inlet of the strip straightening machine, and the inlet of the pinch rollers matches the uncoiler 1. The uncoiler 1 has the functions of swinging, lifting and telescopic.

[0029] The pickling tank 7 adopts a two-stage shallow tank turbulent pickling design with an attached circulation system. The acid production temperature is selected to be 60°C-85°C, the acid circulation volume is 500-800L / min, and the acid concentration is 60-180g / L.

[0030] The rinsing tank 8 adopts a five-stage water spray mode, and the final spray beam uses desalted water to spray directly to ensure the cleanliness of the board surface. The water temperature of the rinsing tank is controlled at 45℃-60℃, and the conductivity of the rinsing water in the final rinsing tank is controlled below 80μS / cm.

[0031] The hot air drying box 9 adopts hot air circulation, steam heat exchange heating mode, condensed water recovery, and is used to replenish the water level of the rinsing tank. The temperature of the hot air drying box is controlled at 90℃-105℃. The circulating air volume is 6000-12000m³ / h.

[0032] The slitting shear 10 adopts a double shearing mode, one set is put into operation and the other set is standby, and there is no need to stop the machine when switching specifications. The blade thickness of the slitting shear 10 is 15-35mm, and the blade diameter is 405-420mm. The diameter difference of the blades on the same blade shaft is controlled within 0.5mm, and the diameter difference of the blades on the upper and lower blade shafts is controlled within 2mm. The gap between the blades is 10%-15% of the product thickness, and the overlap of the blades is 10%-30% of the product thickness.

[0033] The main heat source of the heating furnace 11 adopts electromagnetic induction heating, and the auxiliary heat source adopts electric radiation tube heating. The rated power of the electromagnetic induction heater is 650kW, and the maximum heating temperature is 550℃. The furnace adopts nitrogen and hydrogen mixed protective gas, with a hydrogen content of 5%-15%, a furnace pressure of 50-150Pa, an oxygen content of less than 80ppm, and a dew point of less than -20℃.

[0034] Zinc pot 12 adopts ceramic zinc pot, dual induction heating mode, zinc liquid temperature 450℃-480℃, zinc pot capacity 90-110 tons. Equipped with steering roller and zinc layer control device, steering roller diameter 760-800mm; zinc layer control range 40-500g / ㎡.

[0035] The passivation tank 17 adopts the spraying, purging and squeezing passivation modes; trivalent chromium passivation solution or chromium-free passivation solution can be used; the thickness of the passivation film is controlled to be 30-120 mg / ㎡.

[0036] The passivation drying box 18 adopts hot air circulation and electric heating mode. The drying circulation air temperature is 120℃-180℃. The drying plate temperature is 60℃-80℃.

[0037] The cut-to-length shear 19 is controlled by a servo motor and hydraulic pressure. The cut-to-length is controlled by the servo motor and the cutting is controlled by the hydraulic shear. The product length is 2500mm-9000mm. The shear thickness range is 1.5mm-7.5mm.

[0038] The palletizer 20 is equipped with a cut-to-length shear for automatic palletizing. The palletizing length range is 2000-9000mm, the width range is 200mm-600mm, and the maximum palletizing weight is 6 tons.

Claims

1. A continuous pickling galvanized flat steel production line, characterized by: The invention comprises an uncoiler (1), a straightening machine (2), a hydraulic shear (3), a welding machine (4), a horizontal looper (5), a descaling machine (6), a pickling tank (7), a rinsing tank (8), a hot air drying box (9), a slitting shear (10), a heating furnace (11), a zinc pot (12), a movable bellows (13), a cooling bellows (14), a water cooling tank (15), a finished product straightening machine (16), a passivation tank (17), a passivation drying box (18), a cut-to-length shear (19) and a palletizer (20), which are arranged in sequence.

2. A continuous pickling galvanized flat steel production line according to claim 1, characterized in that: The straightening machine (2) is an integral structure consisting of a pinch roller and a strip straightening machine, and the straightening machine (2) cooperates with the uncoiler (1).

3. A continuous pickling galvanized flat steel production line according to claim 2, characterized in that: The pinch rollers in the straightening machine (2) include an upper straightening pinch roller (26) and a lower straightening pinch roller (27). The upper straightening pinch roller (26) and the lower straightening pinch roller (27) are mounted on a frame of the strip straightening machine. The lower straightening pinch roller (27) and the lower straightening roller group (30) are on the same horizontal plane. The outlet of the pinch rollers matches the inlet of the strip straightening machine, and the inlet of the pinch rollers matches the uncoiler (1).

4. A continuous pickling galvanized flat steel production line according to claim 1, characterized in that: There are two uncoilers (1), one for use and one for backup.

5. A continuous pickling galvanized flat steel production process, characterized in that: The continuous pickling galvanized flat steel production line according to claims 1 to 4 is adopted and operated according to the following steps: a. The hot-rolled strip is uncoiled by the uncoiler (1), and enters the straightening machine (2) to straighten the strip head. The unqualified part of the strip head is cut off by the hydraulic shear (3), and sent to the welding machine (4) for preparation and waiting for welding; b. When the production of the running strip steel is completed, the tail of the strip steel is separated from the coiler (1) and enters the straightening machine (2) for straightening. The unqualified part of the tail of the strip steel is cut off by a hydraulic shear (3) and the tail is sent to the welding machine (4). The head of the waiting steel coil is sent to the welding machine (4), and the head and tail of the two strip steel coils are welded together to ensure the continuous operation of the production line; c. When the strip is being tail-flipped or welded, the horizontal looper (5) enters the looping procedure, so that the back-end process can still be in production while the front-end process is stopped; d. After welding is completed, the uncoiler (1) resumes operation, and the production speed exceeds the rear end production speed, so as to achieve the purpose of punching the horizontal looper (5); the other uncoiler (1) performs coiling and preparation work; e. After the strip reaches the descaling machine (6), it is repeatedly bent and stretched to break the iron oxide scale on the surface of the hot-rolled strip, and part of the iron oxide scale falls off; f. The strip is cleaned of iron oxide scale in the pickling tank (7), and the residual acid is rinsed clean in the rinsing tank (8). The surface moisture of the strip is dried in the hot air drying box (9), and then enters the slitting shear (10) for stripping; g. The slitting machine (10) sets the number and width of strips according to the production process requirements. After the strip is slitting, it enters the heating furnace (11) for heating; and then enters the zinc pot (12) for galvanizing; h. After the flat steel leaves the zinc pot (12), it is cooled by the moving bellows (13) and the cooling bellows (14), and then enters the water cooling tank (15) for final cooling; i. After the flat steel is cooled to the target temperature, it enters the finished product straightening machine (16) for straightening, then enters the passivation tank (17) for passivation, and is dried in the passivation drying box (18); j. After drying, the flat steel is cut to the target length by a cutter (19) and then stacked and packaged by a palletizer (20).

6. A continuous pickling galvanized flat steel production process according to claim 5, characterized in that: The acid production temperature in the pickling tank (7) is 60°C-85°C, the acid circulation volume is 500-800L / min, and the acid concentration is 60-180g / L; the rinsing water temperature in the rinsing tank (8) is 45°C-60°C, and the conductivity is controlled below 80μS / cm; the temperature of the hot air drying box (9) is controlled at 90°C-105°C; the circulating air volume is 6000-12000m³ / h; the heating furnace (11) adopts electromagnetic induction heating, the electromagnetic induction heater has a rated power of 650kW, a maximum heating temperature of 550°C, a nitrogen-hydrogen mixed protective gas is used in the furnace, the hydrogen content is 5%-15%, the furnace pressure is 50-150Pa, the oxygen content is less than 80ppm, and the dew point is less than -20°C; the zinc liquid temperature in the zinc pot (12) is 450°C-480°C; the drying circulating air temperature of the passivation drying box (18) is 120°C-180°C.

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