A control method for improving the curvature of hot-rolled round steel

Abstract

The present invention provides a control method for improving the curvature 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, and a chamfering step. In the fixed-length segmentation step, not only the specifications of the saw blade of the fixed-length segmentation metal saw are adapted to the diameter of the multiple-length blank, but also the radial force generated by the saw blade of the fixed-length segmentation metal saw is offset by a side-pushing clamping device, effectively avoiding the bending of the multiple-length blank due to the radial force generated by the saw blade during the cutting process, improving the curvature of the round steel, thereby reducing the round steel straightening process, reducing the production cost, and shortening the product delivery cycle.

Description

Technical Field

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

[0002] With the transformation and upgrading of the special steel industry and the high-quality development, the downstream steel industry has higher and higher requirements for the curvature of round steel. In the production of round steel, most of the hot-rolled non-finished round steel meets the curvature requirements, but there are still about 5% of round steel that cannot meet the curvature requirements. The round steel that cannot meet the curvature requirements needs to be manually selected first, and then straightened through a separate round steel straightening process, which not only increases the production cost, but also increases the product delivery cycle. Therefore, in order to meet market needs and improve the competitiveness of the client, it is necessary to design a scientific, reasonable and effective hot-rolled round steel curvature control method to improve the curvature of round steel, thereby reducing the round steel straightening process, reducing production costs, and shortening the product delivery cycle. Summary of the invention

[0003] In order to overcome the deficiencies of the prior art, the present invention provides a control method for improving the curvature of hot-rolled round steel, which can effectively improve the curvature of the round steel.

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

[0005] A control method for improving the curvature of hot-rolled round steel, characterized by comprising:

[0006] A heating step, wherein the continuous casting billet is fed into a heating furnace for heating;

[0007] 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;

[0008] 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;

[0009] 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;

[0010] In the step of removing defects from the intermediate rolling, the head defect section and the tail defect section of the intermediate rolling billet are removed by using a No. 1 flying shear;

[0011] 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;

[0012] 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 round steel 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.

[0013] The fixed-length segmentation step includes obtaining the length of the multiple-length blank, calculating the fixed-length length according to the designed length of the finished round steel and the temperature of the multiple-length blank, and segmenting the multiple-length blank according to the fixed-length length using a fixed-length segmentation metal saw and a side-pushing and pressing device to obtain a plurality of fixed-length blanks, wherein the saw blade of the fixed-length segmentation metal saw has a specification that matches the diameter of the multiple-length blank, and the side-pushing and pressing device can offset the radial force generated by the saw blade of the fixed-length segmentation metal saw;

[0014] Cooling step, sending the cut-to-size blanks to a cooling bed for cooling;

[0015] The chamfering step is to chamfer the cooled fixed-size billet to obtain a finished round steel.

[0016] Furthermore, in the heating step, the heating furnace heats the continuous casting billet to 1160±20°C, and the heating furnace is a walking beam heating furnace.

[0017] Furthermore, in the rough rolling step, the rough rolling mill is a single two-roll reversible rolling mill.

[0018] Furthermore, 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.

[0019] Furthermore, 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.

[0020] Further, in the multiple-length segmentation step, the multiple-length length is equal to the design length of the finished round steel × the number of finished round steels 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 round steels 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 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 finished rolled round steel - (N × the first multiple-length length + N × the second multiple-length 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 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 the fixed-length segmentation metal saw to segment the multiple-length round steel according to the fixed-length length.

[0021] Furthermore, in the cut-to-length segmentation step, the cut-to-length length is equal to the designed length of the finished round steel × (1 + the shrinkage rate corresponding to the actual temperature of the multiple-length billet) + the tolerance reserve value.

[0022] Further, in the sizing and segmentation step:

[0023] If the diameter of the double-length blank is less than or equal to 90 mm, the specifications of the saw blade of the fixed-length segmented metal saw are: isosceles triangle saw teeth, the saw tooth angle is 60°, and the number of saw teeth is 342;

[0024] If the diameter of the double-length blank is greater than 90 mm and less than 120 mm, the specifications of the saw blade of the fixed-length segmented metal saw are: wolf-tooth-shaped saw teeth, the saw tooth angle is 55°, and the number of saw teeth is 320;

[0025] If the diameter of the double-length blank is greater than or equal to 120 mm, the specifications of the saw blade of the fixed-length segmented metal saw are: wolf-tooth-shaped saw teeth, a saw tooth angle of 60°, and 200 saw teeth.

[0026] Furthermore, in the length-fixing and segmenting step, the length-fixing and segmenting metal saw is located on one side of the multiple-length blank, and the side-pushing and clamping device is located on the other side of the multiple-length blank, and the side-pushing and clamping device includes a hydraulic power part extending along the radial direction of the multiple-length blank, and a push plate provided at one end of the hydraulic power part close to the multiple-length blank;

[0027] The force F1 exerted by the hydraulic power part of the side push clamping device on the push plate satisfies the following formula: Where: L a is the distance between the push plate of the side push clamping device and a support point, the support point being a support point adjacent to an end of the side push clamping device away from the cut-to-length segmented metal saw;

[0028] L b The length of the push plate of the side push clamping device;

[0029] L c The distance between the push plate of the side push clamping device and the saw blade of the cut-to-length segmented metal saw;

[0030] F2 is the radial force exerted by the saw blade of the fixed-size segmented metal saw on the double-size blank.

[0031] Furthermore, in the sizing and segmenting step, the sawing temperature of the sizing and segmenting metal saw is greater than or equal to 650°C.

[0032] The beneficial effects of the present invention are:

[0033] The present invention provides a method for controlling the sizing accuracy of hot-rolled round steel, which 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 multiple-length segmentation step, a sizing segmentation step, a cooling step, and a chamfering step. In the sizing segmentation step, not only the specifications of the saw blade of the sizing segmentation metal saw are adapted to the diameter of the multiple-length blank, but also the radial force generated by the saw blade of the sizing segmentation metal saw is offset by a side-pushing clamping device, effectively avoiding the bending of the multiple-length blank due to the radial force generated by the saw blade during the cutting process, improving the curvature of the round steel, thereby reducing the round steel straightening process, reducing the production cost, and shortening the product delivery cycle.

[0034] In addition, the present invention also takes into account the influence of temperature in the multiple-length segmentation step and the fixed-length segmentation step, and calculates the multiple-length length and the fixed-length length according to the temperature, thereby eliminating the error caused by thermal expansion and contraction, which is beneficial to improving the hit rate of fixed-length accuracy, reducing the occurrence rate of fixed-length re-cutting, and improving the metal recovery rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0036] Figure 1 is a schematic diagram of the process of this embodiment;

[0037] Figure 2 Schematic diagram of the location of the cut-to-length metal segment saw, the side push clamping device and the support points. DETAILED DESCRIPTION

[0038] The drawings are only used for illustrative purposes and should not be construed as limitations of this patent. In order to better illustrate this embodiment, some parts of the drawings may be omitted, enlarged, or reduced, and do not represent the size of the actual product.

[0039] For those skilled in the art, it is understandable that some well-known structures and their descriptions may be omitted in the drawings. The technical solution of the present invention is further described below in conjunction with the drawings and embodiments.

[0040] As attached Figure 1 A control method for improving the curvature of hot-rolled round steel is shown, comprising:

[0041] A heating step, wherein the continuous casting billet is fed into a heating furnace for heating;

[0042] 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;

[0043] 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;

[0044] 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;

[0045] In the step of removing defects from the intermediate rolling, the head defect section and the tail defect section of the intermediate rolling billet are removed by using a No. 1 flying shear;

[0046] 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;

[0047] 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 round steel 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.

[0048] The fixed-length segmentation step includes obtaining the length of the multiple-length blank, calculating the fixed-length length according to the designed length of the finished round steel and the temperature of the multiple-length blank, and segmenting the multiple-length blank according to the fixed-length length using a fixed-length segmentation metal saw and a side-pushing and pressing device to obtain a plurality of fixed-length blanks, wherein the saw blade of the fixed-length segmentation metal saw has a specification that matches the diameter of the multiple-length blank, and the side-pushing and pressing device can offset the radial force generated by the saw blade of the fixed-length segmentation metal saw;

[0049] Cooling step, sending the cut-to-size blanks to a cooling bed for cooling;

[0050] The chamfering step is to chamfer the cooled fixed-size billet to obtain a finished round steel.

[0051] Preferably, in the heating step, the continuous casting billet is heated to 1160±20° C. by a heating furnace, and the heating furnace is a walking beam heating furnace.

[0052] Preferably, in the rough rolling step, the rough rolling mill is a single two-roll reversible rolling mill.

[0053] Preferably, 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.

[0054] Preferably, 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.

[0055] Preferably, in the multiple-length segmentation step, the multiple-length length is equal to the designed length of the finished round steel × the number of finished round steels 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 round steels 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 finished 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 continuous casting billet - 1) is less than the second multiple-length length, N is an integer greater than or equal to zero, and if the length of the multiple-length round steel is 1 multiple-length, there is no need to use the fixed-length segmented metal saw to segment the multiple-length round steel according to the fixed-length length.

[0056] Preferably, in the step of sizing and segmenting, the sizing length is equal to the designed length of the finished round steel × (1 + the shrinkage rate corresponding to the actual temperature of the double-sized billet) + the tolerance reserve value.

[0057] Preferably, in the step of sizing and segmenting:

[0058] If the diameter of the double-length blank is less than or equal to 90 mm, the specifications of the saw blade of the fixed-length segmented metal saw are: isosceles triangle saw teeth, the saw tooth angle is 60°, and the number of teeth is 342;

[0059] If the diameter of the double-length blank is greater than 90mm and less than 120mm, the specifications of the saw blade of the fixed-length segmented metal saw are: wolf-tooth-shaped saw teeth, the saw tooth angle is 55°, and the number of saw teeth is 320;

[0060] If the diameter of the double-length blank is greater than or equal to 120 mm, the specifications of the saw blade of the fixed-length segmented metal saw are: wolf-tooth-shaped teeth, a tooth angle of 60°, and 200 teeth.

[0061] Preferably, in the length-fixing and segmenting step, the length-fixing and segmenting metal saw is located on one side of the multiple-length blank, and the side-pushing and clamping device is located on the other side of the multiple-length blank, and the side-pushing and clamping device includes a hydraulic power member extending along the radial direction of the multiple-length blank, and a push plate provided at one end of the hydraulic power member close to the multiple-length blank;

[0062] The force F1 exerted by the hydraulic power part of the side push clamping device on the push plate satisfies the following formula: Among them, as attached Figure 2 Shown: L a L is the distance between the push plate of the side push clamping device and the support point, which is the support point adjacent to the end of the side push clamping device away from the fixed-length segmented metal saw; b L is the length of the push plate of the side push clamping device; cis the distance between the push plate of the side push clamping device and the saw blade of the fixed-length segmented metal saw; F2 is the radial force exerted by the saw blade of the fixed-length segmented metal saw on the multiple-length blank.

[0063] Preferably, in the sizing and segmenting step, the sawing temperature of the sizing and segmenting metal saw is greater than or equal to 650°C.

[0064] 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.

[0065] Table 1 Relationship between temperature and cold shrinkage of steel

[0066]

[0067] The following takes the manufacturing of finished round steel with a rod diameter of 100mm, a curvature within 4mm / m, a design length of 5950mm, and a length tolerance range of 0 to 50mm as an example. It is known that the volume of the continuous casting billet at room temperature is 320×425×10000mm, and 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.

[0068] Follow these steps in order:

[0069] In the heating step, the continuous casting billet is sent into a walking beam heating furnace and heated to 1160°C.

[0070] In the rough rolling step, the heated continuous casting billet is sent to a rough rolling mill for rolling to obtain a rough rolled billet of 205×205 mm.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] In the finishing rolling step, the intermediate rolled billet from which the head defect segment and the tail defect segment have been cut off is sent to a finishing rolling mill for rolling to obtain a φ100mm finished round steel.

[0075] The step of multiple-length segmentation: in this step, the actual temperature of the finished round steel is measured to be 800°C, 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 about 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, the multiple-length length of 1 times the length is 5950×(1+9.9‰)+25=6034mm, and the middle section of the finished round steel is segmented into 18122mm and 6034mm using a multiple-length segmentation flying shear to obtain 10 multiple-length round steels of 3 times the length and 1 multiple-length round steel of 1 times the length. It can be understood that the multiple-length round steel of 1 times the length is the fixed-length round steel.

[0076] The step of segmenting the steel length is as follows: in this step, the actual temperature of the double-length round steel is measured to be 650°C, the shrinkage rate corresponding to the actual temperature of the double-length round steel is 8.4‰, and the length of the double-length round steel is calculated to be about 5950×(1+8.4‰)+25=6025mm. The double-length round steel of 3 times the length is segmented by 6025mm using a segmented metal saw to obtain 30 pieces of fixed-length round steel. The saw blade of the segmented metal saw has the following specifications: wolf-tooth-shaped saw teeth, a saw tooth angle of 55°, and 320 saw teeth. In the process of cutting the double-length blank by the segmented metal saw, the radial force generated by the saw blade of the segmented metal saw is offset by a side push clamping device. L a 300mm, L b 330mm, L c It is 300mm, F1 is about 9.9KN, and F2 is about 3.3KN.

[0077] In the cooling step, the cut-to-length round steel is sent to a cooling bed and cooled to 150°C.

[0078] In the chamfering step, when the temperature of the cut-length round steel drops to 150° C., the cut-length round steel is chamfered to obtain a finished round steel.

[0079] Finally, an overhead crane is used to lift the finished round steel into the warehouse.

[0080] In the subsequent sampling stage, the staff randomly selected 50 finished round steels for measurement. The measurement results were: the curvature of the round steel was 2.2 to 3.6 mm / m, there were 10 finished round steels with a length of 5970 mm, 12 finished round steels with a length of 5975 mm, 10 finished round steels with a length of 5978 mm, 9 finished round steels with a length of 5980 mm, and 9 finished round steels with a length of 5981 mm. The curvature of each finished round steel was controlled within 4 mm / m, and the length tolerance range was controlled between 20-31 mm, meeting the design requirements.

[0081] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A control method for improving the curvature 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 section and the tail defect section of 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 round steel 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 includes obtaining the length of the multiple-length blank, calculating the fixed-length length according to the designed length of the finished round steel and the temperature of the multiple-length blank, and segmenting the multiple-length blank according to the fixed-length length using a fixed-length segmentation metal saw and a side-pushing and pressing device to obtain a plurality of fixed-length blanks, wherein the saw blade of the fixed-length segmentation metal saw has a specification that matches the diameter of the multiple-length blank, and the side-pushing and pressing device can offset the radial force generated by the saw blade of the fixed-length segmentation metal saw; Cooling step, sending the cut-to-size blanks to a cooling bed for cooling; A chamfering step is to chamfer the cooled cut-to-size billet to obtain a finished round steel; In the length-segmenting step, the length-segmenting metal saw is located on one side of the multiple-length blank, and the side-pushing and clamping device is located on the other side of the multiple-length blank. The side-pushing and clamping device includes a hydraulic power member extending along the radial direction of the multiple-length blank, and a push plate provided at one end of the hydraulic power member close to the multiple-length blank; The force F1 exerted by the hydraulic power part of the side push clamping device on the push plate satisfies the following formula: ; Among them: L a L is the distance between the push plate of the side push clamping device and the support point, which is the support point adjacent to the end of the side push clamping device away from the fixed-length segmented metal saw; b L is the length of the push plate of the side push clamping device; c is the distance between the push plate of the side push clamping device and the saw blade of the fixed-length segmented metal saw; F2 is the radial force exerted by the saw blade of the fixed-length segmented metal saw on the multiple-length blank.

2. A control method for improving the curvature 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 1160±20° C., and the heating furnace is a walking beam heating furnace.

3. A control method for improving the curvature 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. A control method for improving the curvature 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.

5. A control method for improving the curvature 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.

6. A control method for improving the curvature of hot-rolled round steel according to claim 1, characterized in that: In the multiple length segmentation step, the multiple length length is equal to the design length of the finished round steel × the number of finished round steels 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 round steels 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 times, it is not necessary to use the fixed length segmentation metal saw to segment the multiple length round steel according to the fixed length.

7. A control method for improving the curvature of hot-rolled round steel according to claim 1, characterized in that: In the cut-to-length segmentation step, the cut-to-length length is equal to the designed length of the finished round steel × (1 + the shrinkage rate corresponding to the actual temperature of the double-length billet) + the tolerance reserve value.

8. A control method for improving the curvature of hot-rolled round steel according to claim 1, characterized in that: In the Sizing step: If the diameter of the double-length blank is less than or equal to 90 mm, the specifications of the saw blade of the fixed-length segmented metal saw are: isosceles triangle saw teeth, the saw tooth angle is 60°, and the number of saw teeth is 342; If the diameter of the double-length blank is greater than 90 mm and less than 120 mm, the specifications of the saw blade of the fixed-length segmented metal saw are: wolf-tooth-shaped saw teeth, the saw tooth angle is 55°, and the number of saw teeth is 320; If the diameter of the double-length blank is greater than or equal to 120 mm, the specifications of the saw blade of the fixed-length segmented metal saw are: wolf-tooth-shaped saw teeth, a saw tooth angle of 60°, and 200 saw teeth.

9. A control method for improving the curvature of hot-rolled round steel according to claim 1, characterized in that: In the sizing and segmenting step, the sawing temperature of the sizing and segmenting metal saw is greater than or equal to 650°C.

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