Manufacturing method of rolling girder steel

Abstract

The invention discloses a manufacturing method of rolling girder steel. The method comprises the following steps: heating a girder steel plate blank for rolling; carrying out rough rolling on the heated girder steel plate blank for rolling to obtain strip steel; and the strip steel is subjected to finish rolling, and during finish rolling, the roll bending force of the last rack working roll is dynamically adjusted according to the calculated rolling force. According to the scheme provided by the invention, the continuously changing rolling force is calculated in real time on the final rack of strip steel rolling, and the roll bending force for controlling the plate shape is automatically adjusted according to the calculated value, so that the straightness of the middle strip of the rolling girder is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of steel rolling, in particular to a manufacturing method of roll-pressed girder steel. BACKGROUND

[0002] With the increasingly stringent requirements of "energy saving and emission reduction", the light weight of automobiles has become the main theme of the development of the automobile industry. By increasing the strength and reducing the thickness, the weight of the automobile can be effectively reduced, thereby achieving the purpose of reducing emissions. With the increase of strength, the side bending defects of the strip steel caused by the coupling of various boundary conditions also increase significantly. The main nature of the side bending defect is that the metal extension of the strip steel on both sides along the width direction is uneven, resulting in non-straight bending shape in the length direction (such as bending towards the operating side or the driving side).

[0003] However, in recent years, with the continuous increase of high-strength girder steel and the increasingly stringent requirements of users on side bending, there have been feedbacks on the side bending of girder steel, and the four-split roll-pressed girder steel has a relatively heavy side bending phenomenon. SUMMARY

[0004] Therefore, in order to overcome at least one aspect of the above problems, the embodiments of the present application propose a manufacturing method of roll-pressed girder steel, comprising the following steps: heating a roll-pressed girder steel slab; rough rolling the heated roll-pressed girder steel slab to obtain a strip steel; finely rolling the strip steel, wherein the bending force of the last stand work roll is dynamically adjusted according to the calculated rolling force during fine rolling.

[0005] In some embodiments, the heating of the roll-pressed girder steel slab further comprises: heating the roll-pressed girder steel slab in a heating furnace for a first preset time, wherein the soaking time is not less than the first preset time length, and the furnace is discharged after reaching the target temperature.

[0006] In some embodiments, the first preset time is not less than 200 minutes; the first preset time length is 30 minutes; and the target temperature is 1210-1250℃.

[0007] In some embodiments, the rough rolling of the heated roll-pressed girder steel slab to obtain a strip steel further comprises: adopting a 1+5 rolling mode for rough rolling to obtain a strip steel, wherein the strip steel intermediate slab deviation is ≤30mm.

[0008] In some embodiments, the fine rolling of the strip steel further comprises: the number of the fine rolling stands with opened stand water during fine rolling is not greater than a threshold value.

[0009] In some embodiments, the finishing rolling of the strip steel further comprises: The number of finishing stands with opened stand water during the finishing rolling is not more than 2.

[0010] In some embodiments, the bending force of the work roll of the last stand is dynamically adjusted according to the calculated rolling force during the finishing rolling, and the method further comprises: If the calculated rolling force is less than 900 tons, the bending force of the work roll of the last stand is reduced by 0.15-0.25% every 1 second until the bending force of the work roll of the last stand is reduced by 15-20%.

[0011] In some embodiments, the bending force of the work roll of the last stand is dynamically adjusted according to the calculated rolling force during the finishing rolling, and the method further comprises: If the calculated rolling force is between 900-1100 tons, the bending force of the work roll of the last stand is reduced by 0.25-0.35% every 1 second until the bending force of the work roll of the last stand is reduced by 25-35%.

[0012] In some embodiments, the bending force of the work roll of the last stand is dynamically adjusted according to the calculated rolling force during the finishing rolling, and the method further comprises: If the calculated rolling force is greater than 1100 tons, the bending force of the work roll of the last stand is reduced by 0.30-0.45% every 1 second until the bending force of the work roll of the last stand is reduced by 35-45%.

[0013] Based on the same inventive concept, according to another aspect of the present application, embodiments of the present application also provide a rolled girder steel prepared based on the method according to any one of the above.

[0014] The present application has one of the following beneficial technical effects: the scheme provided by the present application automatically adjusts the bending force for controlling the flatness according to the calculated continuously changing rolling force at the last stand of the strip steel rolling, thereby improving the flatness of the intermediate strip of the rolled girder. BRIEF DESCRIPTION OF DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other embodiments can also be obtained by those skilled in the art without creative labor based on these drawings.

[0016] Figure 1 The flowchart of the manufacturing method of the rolled girder steel according to the embodiments of the present application is shown. DETAILED DESCRIPTION

[0017] In order to make the objects, technical solutions and advantages of the present application clearer, the embodiments of the present application are further described in detail below with reference to the drawings.

[0018] It should be noted that all the expressions of "first" and "second" in the embodiments of the present application are used to distinguish two same name non-identical entities or non-identical parameters. It can be seen that "first" and "second" are only for the convenience of description, and should not be understood as a limitation on the embodiments of the present application. The subsequent embodiments will not be described one by one.

[0019] According to one aspect of the present application, the embodiments of the present application propose a manufacturing method of rolled girder steel, as shown in Figure 1 which can include the steps of: S1, heating a rolled girder steel slab; S2, rough rolling the heated rolled girder steel slab to obtain a strip steel; S3, finishing rolling the strip steel, wherein the bending force of the last stand working roll is dynamically adjusted according to the calculated rolling force during finishing rolling.

[0020] The scheme proposed by the present application automatically adjusts the bending force for controlling the shape of the strip steel according to the calculated value of the continuously changing rolling force at the last stand of the strip steel rolling, thereby improving the flatness of the intermediate strip of the rolled girder.

[0021] In some embodiments, heating the rolled girder steel slab further includes: heating the rolled girder steel slab in a heating furnace for a first preset time, wherein the soaking time is not less than the first preset time length, and the slab is discharged after reaching the target temperature.

[0022] In some embodiments, the first preset time is not less than 200 minutes; the first preset time length is 30 minutes; and the target temperature is 1210-1250℃.

[0023] Specifically, the girder steel plate usually contains micro-alloy elements such as Nb, V and Ti, which need to be fully dissolved in austenite in order to precipitate in the subsequent rolling and cooling process, so as to play the role of fine grain strengthening and precipitation strengthening. The key is soaking, and insufficient temperature or time will lead to incomplete dissolution of alloy elements, affecting the final performance. The high discharge temperature is to ensure enough temperature drop space to ensure that the finishing rolling can be completed in the appropriate temperature range. Therefore, the slab strictly executes the heating system, the time satisfies total time≥200min and the soaking time satisfies≥30min, and the temperature satisfies 1230±20℃.

[0024] In some embodiments, the heated roll is roughed with a beam blank to obtain a strip, further comprising: The roughing is performed in a 1+5 rolling mode to obtain a strip, wherein the strip intermediate blank deviation is ≤30 mm.

[0025] Specifically, the roughing is performed in a 1+5 rolling mode high-speed rolling, and the strip intermediate blank deviation is ≤30 mm. By adjusting the roughing mode to 1+5 mode before rolling the beam steel, and adjusting the shape, and ensuring that the intermediate blank camber is <30 mm, the workpiece temperature drop can be reduced, the finish rolling temperature is ensured, and the subsequent stable bite and shape control of the finishing rolling are ensured by strictly controlling the deviation (≤30 mm).

[0026] In some embodiments, the strip is finished, further comprising: The number of finishing mill stands with open stand water during finishing rolling is not more than a threshold value.

[0027] In some embodiments, the strip is finished, further comprising: The number of finishing mill stands with open stand water during finishing rolling is not more than 2 stands.

[0028] Specifically, the inter-stand cooling water (or called descaling water, laminar cooling) can significantly reduce the surface temperature of the strip. For high-strength steel, the deformation resistance is extremely sensitive to temperature. If too many stands are opened for cooling, it will cause the temperature difference between the head and tail of the strip, and the temperature difference between the edge and the core to be too large. Limiting the use of cooling water, for example, the number of finishing mill stands with open stand water during finishing rolling is not more than 2 stands, maintains the uniform and stable temperature of the strip during finishing rolling, thereby realizing the control of the rolling speed and avoiding the fluctuation of laminar cooling conditions caused by high speed.

[0029] In some embodiments, the bending force of the work roll of the last stand is dynamically adjusted according to the calculated rolling force during finishing rolling, further comprising: If the calculated rolling force is less than 900 tons, the bending force of the work roll of the last stand is reduced by 0.15%-0.25% every 1 second until the bending force of the work roll of the last stand is reduced by 15%-20%.

[0030] In some embodiments, the bending force of the work roll of the last stand is dynamically adjusted according to the calculated rolling force during finishing rolling, further comprising: If the calculated rolling force is between 900-1100 tons, the bending force of the work roll of the last stand is reduced by 0.25%-0.35% every 1 second until the bending force of the work roll of the last stand is reduced by 25%-35%.

[0031] In some embodiments, the bending force of the work roll of the last stand is dynamically adjusted according to the calculated rolling force during finishing rolling, further comprising: If the calculated rolling force is greater than 1100 tons, the bending force of the work roll of the last stand is reduced by 0.30%-0.45% every 1 second until the bending force of the work roll of the last stand is reduced by 35%-45%.

[0032] Specifically, the calculated rolling force accurately reflects the hardness of the current rolling condition, and the smaller the rolling force (<900 tons) means that the strip is relatively thin or soft, and the effect caused by the coiling tension is relatively mild, so the reduction ratio is small (15%-20%) and the reduction speed is slow (0.15%-0.25% / second). The greater the rolling force (>1100 tons) means that the strip is thick or has extremely high strength, and the reverse load change caused by the coiling tension is extremely severe, so the bending force must be reduced significantly and quickly (reduction ratio 35%-45%, speed 0.30%-0.45% / second) to intervene powerfully, otherwise serious coiling waves will occur.

[0033] Therefore, when the calculated rolling force of the finishing rolling is <900 tons: when the head of the strip enters the coiling machine to build tension, the bending force of the work roll of the F7 stand is reduced by 0.15%-0.25% every 1 second until the bending force of the work roll of the F7 stand is reduced by 15%-20%; when the calculated rolling force of the finishing rolling is 900-1100 tons: when the head of the strip enters the coiling machine to build tension, the bending force of the work roll of the F7 stand is reduced by 0.25%-0.35% every 1 second until the bending force of the work roll of the F7 stand is reduced by 25%-35%; when the calculated rolling force of the finishing rolling is >1100 tons: when the head of the strip enters the coiling machine to build tension, the bending force of the work roll of the F7 stand is reduced by 0.30%-0.45% every 1 second until the bending force of the work roll of the F7 stand is reduced by 35%-45%.

[0034] Example 1: The finished product thickness of the 590MPa tensile strength rolled girder steel is 8.0mm, the furnace discharge temperature of the heating furnace is 1225℃, the in-furnace time is 211min, the soaking time is 32min, the rough rolling deviation is 15mm, the water setting of the finishing rolling 2 stands is set, the rolling pressure of the finishing rolling mill is set to 1106 tons, the bending force of the last stand is reduced by 0.30% per second after the coiling machine builds tension, the total reduction is 35%, and the outer bending of the middle strip after four-way splitting is 7mm. Example 2 The finished product thickness of the 530MPa tensile strength rolled girder steel is 8.5mm, the furnace discharge temperature of the heating furnace is 1237℃, the in-furnace time is 215min, the soaking time is 36min, the rough rolling deviation is 25mm, the water setting of the finishing rolling 2 stands is set, the rolling force of the finishing rolling mill is set to 1168 tons, the bending force of the last stand is reduced by 0.45% per second after the coiling machine builds tension, the total reduction is 45%, and the outer bending of the middle strip after four-way splitting is 6.7mm.

[0035] Example 3: Tensile strength 510MPa roll for girder steel finished thickness 6.0mm, heating furnace temperature 1233℃, in the furnace time 223min, soaking time 35min, rough rolling deviation 10mm, 1 set of water setting of finishing rolling, finishing mill set rolling force 838 tons, after the coiling machine is built, the last rack bending force is reduced by 0.20% per second, the total reduction is 20%, after four division, the outer bending of the middle strip is 5mm; Example 4: Tensile strength 550MPa roll for girder steel finished thickness 7.5mm, heating furnace temperature 1218℃, in the furnace time 208min, soaking time 31min, rough rolling deviation 22mm, 2 sets of water setting of finishing rolling, finishing mill set rolling force 876 tons, after the coiling machine is built, the last rack bending force is reduced by 0.22% per second, the total reduction is 18%, after four division, the outer bending of the middle strip is 6.2mm.

[0036] Example 5: Tensile strength 510MPa roll for girder steel finished thickness 7.0mm, heating furnace temperature 1229℃, in the furnace time 219min, soaking time 33min, rough rolling deviation 13mm, 1 set of water setting of finishing rolling, finishing mill set rolling force 980 tons, after the coiling machine is built, the last rack bending force is reduced by 0.30% per second, the total reduction is 28%, after four division, the outer bending of the middle strip is 5.5mm.

[0037] Example 6 Tensile strength 570MPa roll for girder steel finished thickness 6.8mm, heating furnace temperature 1242℃, in the furnace time 227min, soaking time 34min, rough rolling deviation 18mm, 1 set of water setting of finishing rolling, finishing mill set rolling force 1053 tons, after the coiling machine is built, the last rack bending force is reduced by 0.32% per second, the total reduction is 30%, after four division, the outer bending of the middle strip is 5.8mm.

[0038] The scheme provided by the present application aims at the outer bending defect of the roll pressed girder steel middle strip, and realizes effective management of the outer bending defect of the roll pressed girder steel by comprehensively controlling the heating temperature, the rough rolling shape and the finishing rolling bending, thereby improving the straightness of the roll pressed girder middle strip, Based on the same inventive concept, according to another aspect of the present application, the embodiments of the present application also provide a roll pressed girder steel prepared based on the following method: The roll pressed girder steel slab is heated; The heated roll pressed girder steel slab is rough rolled to obtain a strip steel; The strip steel is finished rolled, wherein the bending force of the last rack work roll is dynamically adjusted according to the calculated rolling force during the finishing rolling.

[0039] In some embodiments, the heating the roll-formed girder steel slab further comprises: heating the roll-formed girder steel slab in a heating furnace for a first preset time, wherein the soaking time is not less than the first preset time length, and the roll-formed girder steel slab is discharged after reaching a target temperature.

[0040] In some embodiments, the first preset time is not less than 200 minutes; the first preset time length is 30 minutes; and the target temperature is 1210-1250℃.

[0041] In some embodiments, the rough rolling of the heated roll-formed girder steel slab to obtain a strip further comprises: rough rolling the heated roll-formed girder steel slab to obtain a strip by using a 1+5 rolling mode, wherein the strip intermediate blank deviation is ≤30mm.

[0042] In some embodiments, the strip is further subjected to finish rolling, which further comprises: the number of finish rolling stands with opened stand water during finish rolling is not more than a threshold value.

[0043] In some embodiments, the strip is further subjected to finish rolling, which further comprises: the number of finish rolling stands with opened stand water during finish rolling is not more than 2 stands.

[0044] In some embodiments, the finish rolling further comprises dynamically adjusting the bending force of the work roll of the last stand according to the calculated rolling force, which further comprises: if the calculated rolling force is less than 900 tons, the bending force of the work roll of the last stand is reduced by 0.15%-0.25% every 1 second until the bending force of the work roll of the last stand is reduced by 15%-20%.

[0045] In some embodiments, the finish rolling further comprises dynamically adjusting the bending force of the work roll of the last stand according to the calculated rolling force, which further comprises: if the calculated rolling force is between 900-1100 tons, the bending force of the work roll of the last stand is reduced by 0.25%-0.35% every 1 second until the bending force of the work roll of the last stand is reduced by 25%-35%.

[0046] In some embodiments, the finish rolling further comprises dynamically adjusting the bending force of the work roll of the last stand according to the calculated rolling force, which further comprises: if the calculated rolling force is greater than 1100 tons, the bending force of the work roll of the last stand is reduced by 0.30%-0.45% every 1 second until the bending force of the work roll of the last stand is reduced by 35%-45%.

[0047] The above are exemplary embodiments disclosed by the present application, but it should be noted that various changes and modifications can be made without departing from the scope of the embodiments disclosed by the present application defined by the claims. The functions, steps and / or actions of the method claims described herein need not be performed in any particular order. Furthermore, although elements of the embodiments disclosed by the present application can be described or claimed in individual form, unless explicitly restricted, they can also be implemented in multiple forms.

[0048] It should be understood that, as used herein, the singular forms "a", "an" and "the" are intended to include plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising", or "includes" and / or "including" when used herein, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0049] The above-mentioned embodiment number of the embodiments of the present application is only for description, not representing the advantages or disadvantages of the embodiments.

[0050] Those skilled in the art should understand that the above discussion of any embodiment is only exemplary, and is not intended to imply that the scope of the embodiments disclosed by the present application (including the claims) is limited to these examples; under the idea of the embodiments of the present application, the above embodiments or technical features in different embodiments can also be combined, and there are many other changes of the different aspects of the embodiments of the present application as above. In order to be brief, they are not provided in details. Therefore, any omission, modification, equivalent replacement, improvement, etc. made within the spirit and principles of the embodiments of the present application shall be included in the protection scope of the embodiments of the present application.

Claims

1. A method of manufacturing a rolled girder steel, characterized in that, The method comprises the following steps: heating a rolled girder steel slab; rough rolling the heated rolled girder steel slab to obtain a strip steel; finely rolling the strip steel, wherein the bending force of the working roller of the last stand is dynamically adjusted according to the calculated rolling force.

2. The method of claim 1, wherein, The method further comprises the following steps: heating the rolled girder steel slab in a heating furnace for a first preset time, wherein the soaking time is not less than the first preset time, and the rolled girder steel slab is discharged after reaching a target temperature.

3. The method of claim 2, wherein, The first preset time is not less than 200 minutes, the first preset time is 30 minutes, and the target temperature is 1210-1250 DEG C.

4. The method of claim 1, wherein, The method further comprises the following steps: rough rolling the heated rolled girder steel slab to obtain a strip steel by adopting a 1+5 rolling mode, wherein the strip steel intermediate slab deviation is less than or equal to 30 mm.

5. The method of claim 1, wherein, The method further comprises the following steps: the number of the rolling stands with opened water during the fine rolling is not more than a threshold value.

6. The method of claim 5, wherein, The method further comprises the following steps: the number of the rolling stands with opened water during the fine rolling is not more than 2.

7. The method of claim 1, wherein, The method further comprises the following steps: if the calculated rolling force is less than 900 tons, the bending force of the working roller of the last stand is reduced by 0.15-0.25% every 1 second until the bending force of the working roller of the last stand is reduced by 15-20%.

8. The method of claim 1, wherein, The method further comprises the following steps: if the calculated rolling force is between 900 and 1100 tons, the bending force of the working roller of the last stand is reduced by 0.25-0.35% every 1 second until the bending force of the working roller of the last stand is reduced by 25-35%.

9. The method of claim 1, wherein, The method further comprises the following steps: if the calculated rolling force is greater than 1100 tons, the bending force of the working roller of the last stand is reduced by 0.30-0.45% every 1 second until the bending force of the working roller of the last stand is reduced by 35-45%.

10. A rolled girder steel, characterised in that, The rolled girder steel is prepared based on the method according to any one of claims 1-9.

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