A controlled rolling and cooling process for multi-cut flat materials

Abstract

The present invention belongs to the technical field of steel rolling, and specifically relates to a controlled rolling and controlled cooling process for multi-cut flat materials. Under the premise of not changing the existing arrangement of the three-rolling mill, a cooling water tank is added after the intermediate rolling to cool the flat materials; after the finished rolling, the rolled pieces are cooled through water to control the cooling temperature. The controlled rolling and controlled cooling process is adopted to reduce the alloy components in the steel billet, eliminate the addition of vanadium alloys, reduce the cost per ton of steel, and improve the stability of the mechanical properties of steel. In terms of energy saving and environmental protection, the present invention saves a large amount of precious alloys, increases revenue by 15 million yuan, reduces energy loss, and protects environmental safety. The implementation of the present invention can improve the utilization rate of alloys, improve its own technical level from the aspect of cost reduction, meet production needs and increase production capacity. This technology is a precedent for water-penetrating multi-cut flat materials, and can be promoted to other multi-cut production lines in the future.

Description

Technical Field

[0001] The invention belongs to the technical field of steel rolling, and in particular relates to a controlled rolling and controlled cooling process for multi-cut flat materials. Background Art

[0002] The third rolling mill is a multi-cut bar production line. Since the multi-cut production line has strict requirements on the incoming materials of the intermediate rolling mill, when the intermediate rolling mill produces round materials, the distance from the intermediate rolling mill to the finishing rolling mill is about 40 meters. The cylindrical rolled pieces are prone to twisting when running over a long distance, which is often called the steel inversion phenomenon. Because of the hole shape and filling of the last stand of the intermediate rolling mill, it is impossible to ensure that the round materials are regular cylinders. This causes certain fluctuations in the material shape after finishing rolling, and causes instability in the material shape of the pre-cutting stand. There is a certain influence on the negative difference and line difference between the lines after multiple cutting, so the flat rollers of the first stand of the finishing rolling mill are moved forward to the last stand of the intermediate rolling mill to produce flat materials.

[0003] Previously, the three rolling processes were hot-rolled and the composition was adopted. With the gradual development of controlled rolling and controlled cooling technology and the increasing consumption of alloy resources such as Si, Mn, and V, the controlled rolling and controlled cooling process with low alloy consumption is the general trend. However, the common multi-cutting controlled rolling and controlled cooling process is water penetration of round materials after intermediate rolling or water penetration of rolled pieces after cutting, which has a series of problems such as poor material stability, excessive load of finishing rolling equipment, and cracks in the roll groove:

[0004] 1) Since most cylindrical rolled pieces are pierced with water after rolling in the current steel rolling controlled rolling process, if rectangular flat pieces are to be pierced with water, special cooling nozzles need to be made and special cooling water tanks need to be designed.

[0005] 2) The rectangular flat material produced by the intermediate rolling is cooled through water. Since the rectangular flat material has the problem of faster cooling at the edges and slower cooling in the middle, there will be uneven cooling after water cooling, which will affect the stability of the finishing rolling area and the mechanical properties of the finished product.

[0006] 3) When the rectangular flat material passes through the water piercer, it must be in the middle of the water piercer. If it is too high or too low, or too left or right, the cooling temperature on the other side will be too low. How to control the rolled piece to be in the middle of the water piercer needs to be solved.

[0007] 4) After adopting the controlled rolling and controlled cooling process, the temperature of the finishing rolling area decreases, and the loads of the universal joint, motor, reducer, etc. increase accordingly, which may cause the equipment load to exceed the rated upper limit.

[0008] 5) After the temperature in the finishing rolling area is lowered, the width expansion coefficient of the entire finishing rolling area changes, and the material type and elongation coefficient are different from the original process. It is necessary to re-explore the material type and elongation coefficient of the finishing rolling area.

[0009] 6) The material of the finished rolling mill rolls is tungsten carbide. The characteristics of tungsten carbide rolls are hard and brittle. After the temperature in the finishing area is lowered, the tungsten carbide rolls may have problems such as cracks, groove collapse, and meat loss.

[0010] 7) The temperature at the multiple-length flying shear after the finished product is lower than that of the original process, and the flying shear heat detection signal may fail, resulting in the flying shear not shearing or shearing by mistake, and the flying shear shearing capacity may be insufficient.

[0011] 8) Red rust appears on the steel surface after cooling.

[0012] 9) After intermediate rolling, the temperature on both sides of the flat material is low due to water cooling, which causes the performance of the finished products on both sides to be significantly higher than that of the intermediate products after fine rolling and multiple cutting. There is a margin in performance on both sides but a smaller margin in performance in the middle, which restricts the reduction of alloy composition.

[0013] 10) After the flat material passes through water during intermediate rolling, the temperature at the head is low, forming black heads, which cause great impact on the rollers and process parts in the finishing rolling area, and easily cause rolling guide failures, resulting in steel piling. Summary of the invention

[0014] The purpose of the present invention is to provide a controlled rolling and cooling process for multi-cut flat materials, by cooling the flat materials after intermediate rolling, controlling the rolling temperature, and utilizing the "fine grain strengthening" mechanism to reduce alloy consumption, reduce the cost per ton of steel, and improve product performance stability.

[0015] The technical solution adopted by the present invention to solve the technical problem is: a multi-cut flat material controlled rolling and controlled cooling process, comprising the following steps:

[0016] 1) Design and manufacture a special rectangular water penetrator according to the size of the flat material. The annular seams on all four sides can be adjusted, and the annular seams are adjusted according to the actual experimental results to ensure uniform cooling;

[0017] 2) After the flat material is put into water, tugboats and guide wheel devices are added in front of and inside the water tank to support the stable operation of the rolled piece;

[0018] 3) Carry out temperature reduction test at a certain gradient, test the maximum load capacity of the equipment under the premise of meeting the mechanical properties requirements of the steel, and expand and upgrade the equipment if the equipment capacity cannot meet the production batches;

[0019] 4) Gradually conduct incremental tests to adjust and optimize the material type and elongation coefficient parameters of the finishing rolling area according to the finished product size and the stacking and pulling relationship of the finishing rolling area;

[0020] 5) Summarize the wear of the rollers in the finishing rolling area after the temperature drops to the target temperature and the use of tungsten carbide rollers in the finished product batches, and reduce the wear by adjusting the material type and parameters. If the problem cannot be solved, communicate with the roller manufacturer and use new material rollers for replacement;

[0021] 6) The thermal detection used for signal collection before and after the multiple-length shear is replaced by the low-temperature thermal detection from the high-temperature thermal detection, and the multiple-length shear advance rate parameter is adjusted according to the shearing state of the multiple-length shear;

[0022] 7) After the gradient cooling, find out the upper cooling bed temperature where red rust appears on the steel surface. Then the upper cooling bed temperature is strictly controlled above the above temperature. Track the water blocking effect after water penetration. If there is a problem of water carrying backwards, optimize and improve the water blocking in time.

[0023] 8) The electrical program adds a non-cooling section design to ensure that the steel head is not cooled.

[0024] The present invention has the following beneficial effects:

[0025] Under the premise of not changing the existing arrangement of the three-rolling mill, the present invention adds a cooling water tank after the intermediate rolling to cool the flat material; after the finished rolling, the rolled piece is water-cooled to control the cooling temperature, and a controlled rolling and controlled cooling process is adopted to reduce the alloy component in the steel billet, eliminate the addition of vanadium alloy, reduce the cost per ton of steel, and improve the stability of the mechanical properties of the steel.

[0026] The multi-cut flat bar controlled rolling and controlled cooling process of the present invention eliminates the addition of vanadium alloy to HRB400E steel, meets the seismic performance requirements, reduces the performance gap between each line after cutting, and improves the stability of the mechanical properties of the steel.

[0027] In terms of energy saving and environmental protection, the present invention saves a large amount of precious alloys, increases revenue by 15 million yuan, reduces energy loss, and protects environmental safety.

[0028] The implementation of the present invention can improve the utilization rate of alloys, improve the technical level of the invention from the aspect of cost reduction, meet production needs and increase production capacity. This technology is a precedent for multi-cut flat materials through water, and can be promoted to other multi-cut production lines in the future. DETAILED DESCRIPTION

[0029] The following are specific embodiments of the present invention, which further describe the technical solution of the present invention, but the protection scope of the present invention is not limited to these embodiments. Any changes or equivalent substitutions that do not deviate from the concept of the present invention are included in the protection scope of the present invention.

[0030] A controlled rolling and controlled cooling process for multi-cut flat materials, comprising the following steps:

[0031] 1) Design and manufacture special cooling nozzles and cooling water tanks according to the size of flat materials, i.e., rectangular water penetrators. The annular seams on all four sides can be adjusted, and the annular seams are adjusted according to the actual experimental results to ensure uniform cooling; design the annular seams of the cooling nozzles, seal the annular seams on both sides, and ensure that only the middle part of the rolled piece is cooled. Use a thermometer to measure the temperature of the side and the middle part of the top of the rectangular flat material. By continuously optimizing the design of the annular seams, the temperature difference between the middle of the top and bottom and the two sides of the flat material can be reduced.

[0032] 2) After the flat material is put into water, tugboats and guide wheel devices are added in front of and inside the water tank to support the stable operation of the rolled piece; a similar guide device is added in front of the water inlet tank, connected with oil and gas lubrication and water cooling, and the distance between the two guide wheels is adjusted to be consistent with the width of the flat material after rolling, and the rolled piece is supported to ensure that it is located in the middle of the cooling nozzle in the horizontal direction; tugboats are added between the cooling nozzles in the water tank to tow the rolled piece to ensure that it is located in the middle of the cooling nozzle in the vertical direction.

[0033] 3) Carry out cooling test at a certain gradient, test the maximum load capacity of the equipment under the premise of meeting the mechanical properties of steel, and expand and upgrade the equipment if the capacity cannot meet the production schedule. Calculate the torque and load in the finishing area according to the material type, rolling speed, and rolling temperature in the finishing area. Increase the inspection frequency of motors, reducers, universal shafts and other equipment after actual production, and verify whether the equipment capacity can meet the working conditions by testing the vibration value of the reducer and the current value of the motor.

[0034] 4) Gradually conduct incremental tests to adjust and optimize the material type and elongation coefficient parameters of the finishing area according to the finished product size and the stacking and pulling relationship of the finishing area. Through multiple experiments, the material type adjustment of the finishing area is explored and gradually optimized and solidified to form a standard.

[0035] 5) Summarize the wear of the rollers in the finishing rolling area after the temperature drops to the target temperature and the use of tungsten carbide rollers in the finished product batches, and reduce the wear by adjusting the material type and parameters. If the problem cannot be solved, communicate with the roller manufacturer and use new material rollers as replacements. During the test, the use of tungsten carbide rollers was tracked, and the crack phenomenon of tungsten carbide rollers was analyzed. It was found that most of the groove cracks occurred on both sides, which was directly related to the low temperature on both sides after the flat material passed through water and the large force on the grooves on both sides. The solution is first of all a series of innovations to the cooling nozzle seams of flat materials mentioned above to solve the problem of uneven cooling; then the hole type of pre-cutting and cutting batches is designed to reduce the material type on both sides and reduce the force on the grooves on both sides.

[0036] 6) Replace the thermal detection used for signal collection before and after the multiple-length shear from high-temperature thermal detection to low-temperature thermal detection, and adjust the multiple-length shear advance rate parameters according to the shearing state of the multiple-length shear; calibrate the capacity of the multiple-length flying shear, and replace the thermal signal detector within the corresponding temperature range according to the changes in steel temperature.

[0037] 7) The temperature point at which red rust is produced is found through experiments, and improvements are made to avoid the occurrence of red rust by adjusting the composition and controlling water blocking. After gradient cooling, the upper cooling bed temperature at which red rust appears on the surface of the steel is found, and then the upper cooling bed temperature is strictly controlled above the above temperature. The water blocking effect after water penetration is tracked, and if there is a problem of water carrying backward, the water blocking is optimized and improved in time. The temperature of each side of the rolled piece is uniformly controlled after water penetration during intermediate rolling to ensure uniform cooling of the flat material. Through targeted sampling and analysis of the mechanical properties of each line after slitting, it is found that the performance on both sides is significantly higher than that in the middle. By controlling the cooling water tank after fine rolling, the water penetration flow of the two middle lines is increased, and different upper cooling bed temperatures are set for the middle line and the two side lines to narrow the performance gap between the lines.

[0038] 8) The electrical program adds a non-cooling section design to ensure that the head of the steel is not cooled. A heat detection signal instrument is added before the rolled piece enters the cooling water tank after the intermediate rolling. The cooling water tank after the intermediate rolling is designed to delay the water opening according to the signal collected by the heat detection signal instrument to avoid the head of the flat rolled piece, forming a non-cooling section to ensure stable operation when the flat piece enters the finishing rolling.

[0039] The present invention is not limited to the above-mentioned implementation modes, and anyone should be aware of the structural changes made under the enlightenment of the present invention, and all those having the same or similar technical solutions as the present invention fall within the protection scope of the present invention.

[0040] The techniques, shapes, and structural parts not described in detail in the present invention are all well-known techniques.

Claims

1. A controlled rolling and cooling process for multi-cut flat materials, characterized in that: The following steps are involved: 1) Design and manufacture special cooling nozzles and cooling water tanks according to the size of flat materials, i.e., rectangular water penetrators. The annular seams on all four sides can be adjusted, and the annular seams are adjusted according to the actual experimental results to ensure uniform cooling; design the annular seams of the cooling nozzles, block the annular seams on both sides, and ensure that only the middle part of the rolled piece is cooled. Use a thermometer to measure the temperature of the side and the middle part of the top of the rectangular flat material. Through the continuous optimization of the design of the annular seams, reduce the temperature difference between the top and bottom middle and the two sides of the flat material; 2) After the flat material is put into use and passes through water, tugboats and guide wheel devices are added in front of and inside the water tank to support the stable operation of the rolled piece; a guide device is added in front of the water inlet tank, connected with oil and gas lubrication and water cooling, and the distance between the two guide wheels is adjusted to be consistent with the width of the flat material after the rolling, and the rolled piece is supported to ensure that it is located in the middle of the cooling nozzle in the horizontal direction; tugboats are added between the cooling nozzles in the water tank to tow the rolled piece to ensure that it is located in the middle of the cooling nozzle in the vertical direction; 3) Carry out cooling test at a certain gradient, test the maximum load capacity of the equipment under the premise of meeting the mechanical properties of steel, and expand and upgrade the equipment if the capacity cannot meet the production schedule; calculate the torque and load in the finishing area according to the material type, rolling speed and rolling temperature in the finishing area; increase the inspection frequency of motors, reducers and universal shafts after actual production, and verify whether the equipment capacity can meet the working conditions by testing the vibration value of the reducer and the current value of the motor; 4) Gradually conduct incremental tests to adjust and optimize the material type and elongation coefficient parameters of the finishing rolling area according to the finished product size and the stacking and pulling relationship of the finishing rolling area; through multiple experiments, the material type of the finishing rolling area is adjusted and explored, and gradually optimized and solidified to form a standard; 5) Summarize the wear of the rollers in the finishing rolling area after the temperature drops to the target temperature and the use of the tungsten carbide rollers in the finished product batches, and reduce the wear by adjusting the material type and parameters; 6) Replace the thermal detection used for signal collection before and after the multiple-length shear from high-temperature thermal detection to low-temperature thermal detection, and adjust the multiple-length shear advance rate parameters according to the shearing state of the multiple-length shear; check the capacity of the multiple-length flying shear, and replace the thermal signal detector within the corresponding temperature range according to the change of steel temperature; 7) The temperature point where red rust is produced is found through experimental exploration, and the red rust is avoided by adjusting the composition and controlling the water blocking. After gradient cooling, the upper cooling bed temperature where red rust appears on the steel surface is explored, and then the upper cooling bed temperature is strictly controlled above the upper cooling bed temperature where red rust appears on the steel surface. The water blocking effect after water penetration is tracked. If there is a problem of water carrying backward, the water blocking is optimized and improved in time. The temperature of each side of the rolled piece is uniformly controlled after water penetration during intermediate rolling to ensure uniform cooling of the flat material. Through targeted sampling and analysis of the mechanical properties of each line after slitting, it is found that the performance of the two sides is significantly higher than that of the middle. By controlling the cooling water tank after fine rolling, the water penetration flow of the two middle lines is increased, and different upper cooling bed temperatures are set for the middle line and the two side lines to narrow the performance gap between the lines. 8) The electrical program adds a non-cooling section design to ensure that the head of the steel is not cooled; a heat detection signal meter is added before the rolled piece enters the cooling water tank after intermediate rolling. The cooling water tank after intermediate rolling is designed to delay water opening based on the signal collected by the heat detection signal meter to avoid the head of the flat rolled piece, forming a non-cooling section to ensure stable operation of the flat piece when entering the finishing rolling.