A method for controlling the length accuracy of hot-rolled round steel

Abstract

The present invention provides a method for controlling the sizing accuracy of hot-rolled round steel, comprising a heating step, a rough rolling step, a rough rolling defect removal step, an intermediate rolling step, an intermediate rolling defect removal step, a finishing step, a multiple-length segmentation step, a fixed-length segmentation step, a cooling step, a straightening step, and a chamfering step. The present invention can not only improve the hit rate of sizing accuracy and reduce the occurrence rate of sizing re-cutting, but also improve the metal recovery rate.

Description

Technical Field

[0001] The invention relates to the technical field of steel rolling processing, in particular to a method for controlling the sizing accuracy of hot-rolled round steel. Background Art

[0002] Steel rolling production lines utilize a continuous rolling process, and the resulting rolled products can reach hundreds or even thousands of meters in length. To facilitate subsequent production, these products must be segmented and cut to length. With the transformation, upgrading, and high-quality development of the specialty steel industry, downstream steel-using industries are placing increasingly high demands on the sizing accuracy of round steel. To meet market demand and enhance client competitiveness, it is necessary to design a scientific and rational control method for the sizing accuracy of hot-rolled round steel. This approach can improve the accuracy of sizing, reduce the incidence of re-cutting, and increase metal yield. Summary of the Invention

[0003] To overcome the deficiencies of the prior art, the present invention provides a method for controlling the cut-to-length accuracy of hot-rolled round steel, which can not only improve the hit rate of cut-to-length accuracy and reduce the incidence of cut-to-length re-cutting, but also improve the metal yield.

[0004] The present invention adopts the following technical solutions.

[0005] A method for controlling the length accuracy of hot-rolled round steel, comprising:

[0006] The continuous casting slab is fed into a heating furnace for heating;

[0007] The rough rolling step is to feed the heated continuous casting slab into a rough rolling mill for rolling to obtain a rough rolled slab;

[0008] In the rough rolling defect removal step, the head defect section on the rough rolling billet is removed using a No. 1 hydraulic shear;

[0009] In the intermediate rolling step, the rough rolled slab with the head defective section removed is sent to the intermediate rolling mill for rolling to obtain the intermediate rolled slab;

[0010] In the intermediate rolling defect removal step, the head defect segment and the tail defect segment on the intermediate rolling billet are removed using a No. 1 flying shear;

[0011] In the finishing rolling step, the intermediate rolled billet with the head defect segment and the tail defect segment removed is fed into a finishing mill for rolling to obtain a finished rolled round steel bar;

[0012] The multiple-length segmentation step obtains the length of the finished round steel and calculates the multiple-length length based on the designed length of the finished bar and the temperature of the finished round steel. The middle section of the finished round steel is segmented according to the multiple-length length using a multiple-length segmentation flying shear to obtain a number of multiple-length round steels. The remaining head and tail sections of the finished round steel are respectively designated as the head discarded section and the tail discarded section.

[0013] The fixed length segmentation step obtains the length of the double-length round steel and calculates the fixed length according to the designed length of the finished bar and the temperature of the double-length round steel. The double-length round steel is segmented according to the fixed length using a fixed length segmentation metal saw to obtain a plurality of fixed length round steels.

[0014] Cooling step: sending the cut-length round steel to the cooling bed for cooling;

[0015] Straightening step, straightening the cooled cut-length round steel;

[0016] In the chamfering step, the straightened round steel is chamfered to obtain a finished bar.

[0017] Furthermore, in the heating step, the heating furnace heats the continuous casting billet to 1180±20°C, and the heating furnace is a walking beam heating furnace.

[0018] Furthermore, in the rough rolling step, the rough rolling mill is a single two-roll reversible rolling mill.

[0019] Furthermore, in the roughing defect removal step, the length of the head defect segment to be removed from the roughing billet is greater than or equal to 100 mm and does not exceed 800 mm.

[0020] Furthermore, in the intermediate rolling step, the intermediate rolling mill is composed of a plurality of short stress rolling mills arranged alternately in parallel and vertically and connected in series, and the rolling temperature of the intermediate rolling mill is greater than or equal to 900°C.

[0021] Furthermore, in the intermediate rolling defect removal step, the length of the head defect segment and the tail defect segment to be removed from the intermediate rolling billet is greater than or equal to 100 mm and does not exceed 800 mm.

[0022] Furthermore, in the finishing rolling step, the finishing mill is composed of a plurality of short stress rolling mills arranged alternately in parallel and vertical directions and connected in series, and the rolling temperature of the finishing mill is greater than or equal to 850°C.

[0023] Furthermore, in the multiple-length segmentation step, the multiple-length length is equal to the design length of the finished bar × the number of finished bars cut from a single multiple-length round steel × (1 + the cold shear rate corresponding to the actual temperature of the finish-rolled round steel) + the tolerance reserve value × the number of finished bars cut from a single multiple-length round steel + the saw blade thickness of the fixed-length segmented metal saw × (the number of fixed-length round steels cut from a single multiple-length round steel - 1). The multiple-length length includes a first multiple-length length and a second multiple-length length, the first multiple-length length is greater than the second multiple-length length, the length of the finish-rolled round steel - (N × the first multiple-length length + N × the second multiple-length length) - the blade thickness of the multiple-length segmented flying shear × (the number of multiple-length round steels cut from a single continuously cast billet - 1) is less than the second multiple-length length, N is an integer greater than or equal to zero. If the length of the multiple-length round steel is 1 multiple-length, it is not necessary to use the fixed-length segmented metal saw to segment the multiple-length round steel according to the fixed-length length.

[0024] Furthermore, in the step of sizing and segmenting, the sizing length is equal to the design length of the finished bar × (1 + the shrinkage rate corresponding to the actual temperature of the double-length blank) + the tolerance reserve value.

[0025] Furthermore, in the cooling step, the fixed-length round steel is cooled to 550°C to 800°C; and in the chamfering step, the chamfering temperature of the fixed-length round steel is 150°C to 400°C.

[0026] The beneficial effects of the present invention are:

[0027] The present invention provides a method for controlling the cut-to-length accuracy of hot-rolled round steel. The method comprises a heating step, a rough rolling step, a rough rolling defect removal step, an intermediate rolling step, an intermediate rolling defect removal step, a finishing step, a double-length segmentation step, a fixed-length segmentation step, a cooling step, a straightening step, and a chamfering step. The influence of temperature is taken into account in both the double-length segmentation step and the fixed-length segmentation step, and the double-length length and fixed-length length are calculated based on the temperature, thereby eliminating errors caused by thermal expansion and contraction, improving the accuracy of cut-to-length accuracy, reducing the incidence of cut-to-length re-cuts, and improving metal yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0029] Figure 1 Schematic diagram of the process of this embodiment. DETAILED DESCRIPTION

[0030] The accompanying drawings are for illustrative purposes only and should not be construed as limiting this patent. In order to better illustrate this embodiment, certain components of the accompanying drawings may be omitted, enlarged, or reduced in size, and do not represent the actual size of the product.

[0031] It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings. The technical solution of the present invention will be further described below in conjunction with the drawings and embodiments.

[0032] A method for controlling the length accuracy of hot-rolled round steel, comprising:

[0033] The continuous casting slab is fed into a heating furnace for heating;

[0034] The rough rolling step is to feed the heated continuous casting slab into a rough rolling mill for rolling to obtain a rough rolled slab;

[0035] In the rough rolling defect removal step, the head defect section on the rough rolling billet is removed using a No. 1 hydraulic shear;

[0036] In the intermediate rolling step, the rough rolled slab with the head defective section removed is sent to the intermediate rolling mill for rolling to obtain the intermediate rolled slab;

[0037] In the intermediate rolling defect removal step, the head defect segment and the tail defect segment on the intermediate rolling billet are removed using a No. 1 flying shear;

[0038] In the finishing rolling step, the intermediate rolled billet with the head defect segment and the tail defect segment removed is fed into a finishing mill for rolling to obtain a finished rolled round steel bar;

[0039] The multiple-length segmentation step obtains the length of the finished round steel and calculates the multiple-length length based on the designed length of the finished bar and the temperature of the finished round steel. The middle section of the finished round steel is segmented according to the multiple-length length using a multiple-length segmentation flying shear to obtain a number of multiple-length round steels. The remaining head and tail sections of the finished round steel are respectively designated as the head discarded section and the tail discarded section.

[0040] The fixed length segmentation step obtains the length of the double-length round steel and calculates the fixed length according to the designed length of the finished bar and the temperature of the double-length round steel. The double-length round steel is segmented according to the fixed length using a fixed length segmentation metal saw to obtain a plurality of fixed length round steels.

[0041] Cooling step: sending the cut-length round steel to the cooling bed for cooling;

[0042] Straightening step, straightening the cooled cut-length round steel;

[0043] In the chamfering step, the straightened round steel is chamfered to obtain a finished bar.

[0044] Preferably, in the heating step, the heating furnace heats the continuous casting billet to 1180±20° C., and the heating furnace is a walking beam heating furnace.

[0045] Preferably, in the rough rolling step, the rough rolling mill is a single two-roll reversible rolling mill.

[0046] Preferably, in the roughing defect removal step, the length of the head defect segment to be removed from the roughing billet is greater than or equal to 100 mm and does not exceed 800 mm.

[0047] Preferably, in the intermediate rolling step, the intermediate rolling mill is composed of a plurality of short stress rolling mills arranged alternately in parallel and vertically and connected in series, and the rolling temperature of the intermediate rolling mill is greater than or equal to 900°C.

[0048] Preferably, in the intermediate rolling defect removal step, the length of the head defect segment and the tail defect segment to be removed from the intermediate rolling billet is greater than or equal to 100 mm and does not exceed 800 mm.

[0049] Preferably, in the finishing rolling step, the finishing mill is composed of a plurality of short stress rolling mills arranged alternately in parallel and vertical directions and connected in series, and the rolling temperature of the finishing mill is greater than or equal to 850°C.

[0050] Preferably, in the multiple-length segmentation step, the multiple-length length is equal to the designed length of the finished bar × the number of finished bars cut from a single multiple-length round steel × (1 + the cold shear rate corresponding to the actual temperature of the finish-rolled round steel) + the tolerance reserve value × the number of finished bars cut from a single multiple-length round steel + the saw blade thickness of the fixed-length segmented metal saw × (the number of fixed-length round steels cut from a single multiple-length round steel - 1). The multiple-length length includes a first multiple-length length and a second multiple-length length, the first multiple-length length is greater than the second multiple-length length, the length of the finish-rolled round steel - (N × the first multiple-length length + N × the second multiple-length length) - the blade thickness of the multiple-length segmented flying shear × (the number of multiple-length round steels cut from a single continuously cast billet - 1) is less than the second multiple-length length, N is an integer greater than or equal to zero. If the length of the multiple-length round steel is 1 multiple-length, there is no need to use a fixed-length segmented metal saw to segment the multiple-length round steel according to the fixed-length length.

[0051] Preferably, in the step of sizing and segmenting, the sizing length is equal to the designed length of the finished bar × (1 + the shrinkage rate corresponding to the actual temperature of the double-length blank) + the tolerance reserve value.

[0052] It should be noted that in the sizing and segmentation step, the staff can use a handheld laser rangefinder to measure the length from the sizing baffle to the saw blade. If the difference between any two of the set sizing length, the sizing baffle pointer position, and the actual measured length exceeds 5mm, the staff should adjust the equipment in time to ensure that the equipment's accuracy meets the requirements.

[0053] Preferably, in the cooling step, the fixed-length round steel is cooled to 550°C to 800°C; and in the chamfering step, the chamfering temperature of the fixed-length round steel is 150°C to 400°C.

[0054] It should be noted that a ruler is installed on the input roller of the cooling bed, and the staff can use the ruler to visually check the cut length.

[0055] As a further optimization of this embodiment, the number of unprocessed workpieces in each step on the same steel rolling production line should not exceed 2 groups, so as to avoid the workpieces from having a large temperature drop due to long waiting time, thereby causing large fluctuations in the fixed length.

[0056] In practice, the relationship between the temperature of the steel and the cold shrinkage rate can be derived after multiple experiments. In this embodiment, the relationship between the temperature of the steel and the cold shrinkage rate is shown in Table 1.

[0057] Table 1 Relationship between temperature and cold shrinkage of steel

[0058]

[0059] The following takes the manufacturing of finished bars with a rod diameter of 90mm, a design length of 5950mm and a tolerance range of 0 to 50mm as an example. It is known that the volume of the continuous casting billet at room temperature is 320×425×9000mm, the blade thickness of the No. 1 hydraulic shear, the blade thickness of the No. 1 flying shear, the blade thickness of the multiple-size segmented flying shear, and the saw blade thickness of the fixed-size segmented metal saw are all 10mm, and the tolerance reserved value is 25mm.

[0060] Follow these steps in order:

[0061] In the heating step, the continuous casting billet is sent into a walking beam heating furnace and heated to 1180°C.

[0062] In the rough rolling step, the heated continuous casting slab is fed into a rough rolling mill for rolling to obtain a rough rolled slab of 205×205 mm.

[0063] In the rough rolling defect removal step, a No. 1 hydraulic shear is used to remove the head defect segment with a length of 130 mm on the rough rolling billet.

[0064] In the intermediate rolling step, the rough rolled billet with the head defective section cut off is sent to the intermediate rolling mill for rolling to obtain the intermediate rolled billet of φ114mm.

[0065] In the intermediate rolling defect removal step, a No. 1 flying shear is used to remove the head defect segment and the tail defect segment with a length of 130 mm on the intermediate rolling billet.

[0066] In the finishing rolling step, the intermediate rolled billet with the head defect segment and the tail defect segment cut off is sent to the finishing rolling mill for rolling to obtain φ90mm finished rolled round steel.

[0067] The multiple-length segmentation step. In this step, the actual temperature of the finished round steel is measured to be 800°C, and the shrinkage rate corresponding to the actual temperature of the finished round steel is 9.9‰. The calculated length of the finished round steel is approximately 192966mm, and the multiple-length length of 3 times the length is calculated to be 5950×3×(1+9.9‰)+10×2+25×3=18122mm, and the multiple-length length of 1 times the length is 5950×(1+9.9‰)+25=6034mm. The middle section of the finished round steel is segmented into 18122mm and 6034mm using a multiple-length segmented flying shear to obtain 10 3-times-length multiple-length round steels and 1 1-times-length multiple-length round steel. It can be understood that the 1-times-length multiple-length round steel is the fixed-length round steel.

[0068] In this step, the actual temperature of the double-length round steel is measured to be 650°C, and the shrinkage rate corresponding to the actual temperature of the double-length round steel is 8.4‰. The length of the fixed-length round steel is calculated to be approximately 5950×(1+8.4‰)+25=6025mm. The 3-fold double-length round steel is segmented into 6025mm segments using a fixed-length segmentation metal saw to obtain 30 fixed-length round steels.

[0069] In the cooling step, the cut-length round steel is sent to the cooling bed and cooled to 550°C;

[0070] Straightening step: straighten the cooled fixed-length round steel and collect the straightened fixed-length round steel into chamfering frames in bundles of 10;

[0071] In the chamfering step, when the temperature of the cut-length round steel drops to 150° C., the straightened cut-length round steel is chamfered to obtain a finished bar.

[0072] Finally, an overhead crane is used to lift the finished bars into storage.

[0073] In the subsequent random inspection process, the staff randomly selected 50 finished bars for measurement. The measurement results were: 10 finished bars with a length of 5970mm, 12 finished bars with a length of 5975mm, 10 finished bars with a length of 5978mm, 9 finished bars with a length of 5980mm, and 9 finished bars with a length of 5981mm. The tolerance range of each finished bar was controlled between 20-31mm, meeting the precision control requirements of fixed length: 5950mm and fixed length tolerance: 0-50mm.

[0074] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A method for controlling the length accuracy of hot-rolled round steel, characterized in that: include: A heating step, wherein the continuous casting billet is fed into a heating furnace for heating; A rough rolling step, wherein the heated continuous casting billet is sent to a rough rolling mill for rolling to obtain a rough rolled billet; In the rough rolling defect removal step, the head defect section on the rough rolling billet is removed by using a No. 1 hydraulic shear; In the intermediate rolling step, the rough rolled billet from which the defective section at the head has been cut off is sent to the intermediate rolling mill for rolling to obtain the intermediate rolled billet; In the step of removing defects from the intermediate rolling, the head defect segment and the tail defect segment on the intermediate rolling billet are removed by using a No. 1 flying shear; Finishing rolling step, sending the intermediate rolled billet from which the head defect segment and the tail defect segment have been cut off to a finishing rolling mill for rolling to obtain a finished rolled round steel; The multiple-length segmentation step obtains the length of the finished round steel, and calculates the multiple-length length according to the design length of the finished bar and the temperature of the finished round steel. The middle section of the finished round steel is segmented according to the multiple-length length using the multiple-length segmentation flying shear to obtain a plurality of multiple-length round steels. The remaining head section and tail section of the finished round steel are the head discarded section and the tail discarded section respectively. The fixed-length segmentation step obtains the length of the double-length round steel, calculates the fixed-length length according to the designed length of the finished bar and the temperature of the double-length round steel, and uses a fixed-length segmentation metal saw to segment the double-length round steel according to the fixed-length length to obtain a plurality of fixed-length round steels; Cooling step, sending the cut-to-length round steel to a cooling bed for cooling; A straightening step is to straighten the cooled cut-length round steel; The chamfering step is to chamfer the straightened round steel to obtain a finished bar; In the multiple length segmentation step, the multiple length length is equal to the design length of the finished bar × the number of finished bars cut from a single multiple length round steel × (1 + the shrinkage rate corresponding to the actual temperature of the finished rolled round steel) + the tolerance reserve value × the number of finished bars cut from a single multiple length round steel + the saw blade thickness of the fixed length segmentation metal saw × (the number of fixed length round steels cut from a single multiple length round steel - 1), the multiple length length includes the first multiple length and the second multiple length, the first multiple length is greater than the second multiple length, the length of the finished rolled round steel - (N × the first multiple length + N × the second multiple length) - the blade thickness of the multiple length segmentation flying shear × (the number of multiple length round steels cut from a single continuous casting billet - 1) is less than the second multiple length, N is an integer greater than or equal to zero, if the length of the multiple length round steel is 1 multiple length, then there is no need to use the fixed length segmentation metal saw to segment the multiple length round steel according to the fixed length; In the cut-to-length segmentation step, the cut-to-length length is equal to the designed length of the finished bar × (1 + the shrinkage rate corresponding to the actual temperature of the double-length billet) + the tolerance reserve value.

2. A method for controlling the length accuracy of hot-rolled round steel according to claim 1, characterized in that: In the heating step, the heating furnace heats the continuous casting billet to 1180±20° C., and the heating furnace is a walking beam heating furnace.

3. The method for controlling the length accuracy of hot-rolled round steel according to claim 1, characterized in that: In the rough rolling step, the rough rolling mill is a single two-roll reversible rolling mill.

4. The method for controlling the length accuracy of hot-rolled round steel according to claim 1, characterized in that: In the rough rolling defect removal step, the length of the head defect segment to be removed from the rough rolling billet is greater than or equal to 100 mm and does not exceed 800 mm.

5. The method for controlling the length accuracy of hot-rolled round steel according to claim 1, characterized in that: In the intermediate rolling step, the intermediate rolling mill is composed of a plurality of short stress rolling mills which are alternately arranged in parallel and vertical directions and connected in series, and the rolling temperature of the intermediate rolling mill is greater than or equal to 900°C.

6. The method for controlling the length accuracy of hot-rolled round steel according to claim 1, characterized in that: In the intermediate rolling defect removal step, the length of the head defect segment and the tail defect segment to be removed from the intermediate rolling billet is greater than or equal to 100 mm and does not exceed 800 mm.

7. The method for controlling the length accuracy of hot-rolled round steel according to claim 1, characterized in that: In the finishing rolling step, the finishing mill is composed of a plurality of short stress rolling mills which are alternately arranged in parallel and vertical directions and connected in series, and the rolling temperature of the finishing mill is greater than or equal to 850°C.

8. The method for controlling the length accuracy of hot-rolled round steel according to claim 1, characterized in that: In the cooling step, the cut-to-length round steel is cooled to 550° C. to 800° C.; in the chamfering step, the chamfering temperature of the cut-to-length round steel is 150° C. to 400° C.

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