A method for producing 6mm thin steel plates using a heavy plate rolling mill with energy saving and reduced consumption.

Abstract

This invention belongs to the field of hot-rolled plate processing technology, and relates to a method for producing 6mm thin steel plates using a heavy plate rolling mill with energy saving and reduced consumption. By taking control measures on billet cross-section, production planning, equipment parameters, rolling method, straightening process, and flow arrangement, it is possible to produce 6mm thin steel plates with energy saving and reduced consumption without adding a heat treatment process, even when the heavy plate rolling mill has no bending roll function and the rolls are ordinary flat rolls. At the same time, the shape and performance of the steel plates meet the national standards.

Description

Technical Field

[0001] This invention belongs to the field of hot-rolled plate processing technology, and relates to a manufacturing method for producing 6mm thin steel plates using a heavy plate rolling mill that saves energy and reduces consumption. Background Technology

[0002] Medium and heavy plates can be classified into medium plates, heavy plates, and extra-heavy plates according to their thickness. Generally, plates with a thickness of 8mm or less are called thin-gauge steel plates. Because controlling the shape of thin-gauge steel plates is more difficult, they are usually produced on medium plate mills or hot-rolled thin plate continuous rolling mills. Sometimes, due to equipment limitations, thin-gauge steel plates are also produced on heavy plate mills, but the plate shape qualification rate is lower. Often, it is necessary to improve the plate shape by using bending rolls, using special roll types, or adding a heat treatment process after rolling. These methods not only place high demands on the rolling mill and complicate the production process, but also increase production costs.

[0003] In existing technologies, normalizing heat treatment is generally used after rolling on production lines to facilitate plate straightening, but this makes the production process complex and the production cost high. In some production processes, the requirements for roll profile are high. The finishing mill uses SmartCrown roll profile to improve the plate shape control capability of medium and heavy plate mills, which is beneficial for controlling the flatness of steel plates, etc. However, this method is too demanding for the mill and is not universally applicable. In some production lines, after rough rolling, the plate needs to be oscillated on the intermediate roller table to wait for the temperature to rise, which prolongs the production time and is not conducive to the output of finished products. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a method for producing 6mm thin steel plates in an energy-saving and consumption-reducing manner using a heavy plate rolling mill. This method enables the production of 6mm thin steel plates at low cost and high efficiency without the need for additional heat treatment processes, provided that the heavy plate rolling mill has no bending roll function and the rolls are ordinary flat rolls.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for producing 6mm thin-gauge steel plates using a heavy plate rolling mill with energy saving and reduced consumption, comprising the following steps:

[0006] (1) The continuous casting billet with a thickness of 200mm to 300mm is cut into an intermediate billet with a thickness of 70 to 80mm and a width equal to the burr width of the finished steel plate.

[0007] (2) Before rolling, produce more than 14 steel plates of ordinary carbon steel series with a thickness of 8mm and similar width, and then produce steel plates with a thickness of 6mm, transitioning from thick to thin.

[0008] (3) After production scheduling, a walking beam heating furnace is used to ensure uniform heating of the steel billet. The tapping temperature is 1150-1280℃, and the target temperature is 1200℃.

[0009] (4) The slab after exiting the furnace is rolled on a double-stand 4100mm wide and thick plate rolling mill using a full longitudinal rolling method, and an intermediate slab with the required width and thickness is obtained by roughing the slab through a roughing process.

[0010] (5) The intermediate billet is then quickly sent to the finishing mill and the target steel plate is obtained by finishing mill rolling. There is no steel waiting for temperature between roughing and finishing mills, and the steel connection speed between roughing and finishing mills is increased.

[0011] (6) Quickly feed the steel plate from the finishing mill to the straightening machine. The straightening temperature is ≥620℃. Adjust the overstraightening amount and the height of the side rolls according to the straightening condition of the steel plate. Straighten 3 times.

[0012] (7) After straightening, the steel plate is placed on the cooling bed and kept moving on the cooling bed. The gap between the steel plates is >400mm. The flow is fast and the plate should not be piled up on the ground for cooling.

[0013] Optionally, production scheduling can be carried out approximately 7 days after the finishing mill support rolls are changed and about 15 hours after the finishing mill work rolls are changed.

[0014] Optionally, before rolling, the pusher control logic can be adjusted to reduce the pusher clamping speed to 0.2 m / s.

[0015] Optionally, before rolling, check the alignment of the pusher bed before and after finishing rolling, and the alignment measurement of the pusher bed should be within 10mm.

[0016] Optionally, before rolling, turn off the external cooling water of the rolling zone roller table in advance and reduce the cooling water of the roughing and finishing rolls.

[0017] Optionally, the roughing process uses a 3-pass full longitudinal rolling process, with a final rolling temperature of ≥1100℃, a target thickness of 25mm, and no high-pressure water is applied during the roughing process.

[0018] Optionally, the finishing rolling adopts 5 to 7 passes of rapid temperature rolling, with the initial rolling temperature ≥1080℃ and the final rolling temperature ≥850℃; the first pass of the finishing rolling is subjected to high-pressure water descaling, and the last 3 passes are slow bite-in, controlling the rolling speed to 2.0 to 3.5 m / s.

[0019] Optionally, the gap between the guard plates of the finishing mill rolls can be controlled, with the lower roll gap being 3-5 mm and the upper roll gap being 6-8 mm; the lower limit protection limit for the finishing mill AGC roll gap is set to 3 mm.

[0020] Optionally, before finishing rolling, the pre-filled water opening of the finishing mill can be adjusted to 30%.

[0021] Optionally, before straightening, reduce the water level on the straightener rolls and turn off the external cooling water on the roll table; set the roll speed to 2.5 m / s and quickly feed the rolls from the finishing mill to the straightener.

[0022] The beneficial effects of this invention are as follows: By taking control measures on the billet cross-section, production plan, equipment parameters, rolling method, straightening process, and flow arrangement, this invention achieves the production of 6mm thin steel plates without the need for additional heat treatment processes, even when the heavy plate rolling mill has no bending roll function and the rolls are ordinary flat rolls; at the same time, the shape and performance of the steel plates meet the national standards.

[0023] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Detailed Implementation

[0024] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. Specific Implementation

[0026] A method for producing 6mm thin-gauge steel plates using a heavy plate rolling mill with energy saving and reduced consumption includes the following steps:

[0027] (1) The continuous casting billet with a thickness of 200mm to 300mm is cut into an intermediate billet with a thickness of 70 to 80mm and a width equal to the width of the burr of the finished steel plate. The steel grade used is Q345R.

[0028] (2) Rolling is carried out on the 8th day after the change of the support roll and the 15th hour after the change of the work roll. Before rolling the steel plate, 20 ordinary carbon steel plates with a thickness of 8mm and similar width are rolled first.

[0029] (3) After production scheduling, a walking beam heating furnace is used to ensure uniform heating of the steel billet. The tapping temperature is 1150-1280℃, and the target temperature is 1200℃.

[0030] (4) The slab after exiting the furnace is rolled on a double-stand 4100mm wide and thick plate rolling mill using a full longitudinal rolling method. The intermediate slab with the required width and thickness is obtained by roughing the roughing process. The roughing process uses 3 passes of full longitudinal rolling. The final rolling temperature of the roughing process is ≥1100℃. The target thickness of the feed is 25mm. High pressure water is not used in the roughing process.

[0031] (5) After rough rolling, the intermediate billet is quickly sent to the finishing mill and the target steel plate is obtained by finishing rolling. There is no steel waiting between rough rolling and finishing rolling to increase the steel connection speed between rough rolling and finishing rolling. Finish rolling adopts 5 to 7 passes of rapid temperature-preparation rolling. The starting rolling temperature of finishing rolling is ≥1080℃ and the finishing rolling temperature is ≥850℃. The first pass of finishing rolling is sprayed with high pressure water to remove scale, and the last 3 passes are slow bite-in, controlling the rolling speed to be 2.0 to 3.5 m / s.

[0032] (6) Quickly send the steel plate from the finishing mill to the straightening machine. Before straightening, turn off the water in the straightening machine roll body and turn off the external cooling water in the roller table. Set the roll speed to 2.5m / s and the straightening temperature to 652℃. Adjust the overstraightening amount and the height of the side rolls according to the straightening situation of the steel plate. Straighten the entire plate 3 times.

[0033] (7) After straightening, the steel plate is sent to the cooling bed. The steel plate is kept moving on the cooling bed and the gap between the steel plates is >400mm. The steel plate is kept moving on the cooling bed to cool.

[0034] Regarding equipment parameters: Before roughing, adjust the pusher control logic and reduce the pusher clamping speed to 0.2 m / s; check the alignment of the pushers before and after finishing, ensuring the alignment measurement is within 10 mm; turn off the external cooling water of the rolling zone roller table in advance and reduce the cooling water of the roughing and finishing rolls; before finishing rolling, adjust the pre-filling water opening of the finishing mill to 30%; control the gap between the finishing mill roll guard plates, with the lower roll at 3-5 mm and the upper roll at 6-8 mm; set the lower limit protection limit of the finishing mill AGC roll gap to 3 mm.

[0035] Final product thickness: 6mm; unevenness: 5mm / mm; mechanical properties: yield strength 452MPa; tensile strength 562MPa; elongation after fracture 30%; transverse 0℃ KV2: 51J, 43J, 46J; meets production requirements.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for producing 6mm thin-gauge steel plates using an energy-saving and consumption-reducing heavy plate rolling mill, characterized in that, Includes the following steps: (1) The continuous casting billet with a thickness of 200mm~300mm is cut into an intermediate billet with a thickness of 70~80mm and a width equal to the burr width of the finished steel plate; (2) Before rolling, produce 10 to 20 or more steel plates of 8mm thick ordinary carbon steel series with similar widths, and then produce 6mm thick steel plates, transitioning from thick to thin. Production scheduling is to be carried out approximately 7 days after the finishing mill support rolls are changed and about 15 hours after the finishing mill work rolls are changed. (3) After production scheduling, a walking beam heating furnace is used to ensure uniform heating of the steel billet. The tapping temperature is 1150-1280℃, and the target temperature is 1200℃. (4) The slab after exiting the furnace is rolled on a double-stand 4100mm wide and thick plate rolling mill using a full longitudinal rolling method, and an intermediate slab with the required width and thickness is obtained by roughing the slab through a roughing process. (5) The intermediate billet is then quickly sent to the finishing mill and the target steel plate is obtained by finishing mill rolling. There is no steel waiting for temperature between roughing and finishing mills, and the steel connection speed between roughing and finishing mills is increased. (6) Quickly feed the steel plate from the finishing mill to the straightening machine. The straightening temperature is ≥620℃. Adjust the overstraightening amount and the height of the side rolls appropriately according to the straightening condition of the steel plate. Straighten 3 times. Before rolling, turn off the external cooling water of the rolling area roller table in advance and reduce the cooling water of the roughing and finishing rolls; the roughing rolling adopts 3-pass full longitudinal rolling, the final rolling temperature of the roughing rolling is ≥1100℃, the target thickness of the feed is 25mm, and no high-pressure water is used in the roughing rolling; (7) After straightening, the steel plate is placed on the cooling bed and kept moving on the cooling bed. The gap between the steel plates is >400mm. The flow is fast and the plates should not be piled up on the ground for cooling. Before rolling, the pusher control logic is adjusted, and the pusher clamping speed is reduced to 0.2m / s. Before rolling, the alignment of the pushers before and after finishing rolling is checked, and the alignment measurement of the pushers is within 10mm. The gap between the finishing roll body guard plates is controlled, with the lower roll being 3-5mm and the upper roll being 6-8mm. The lower limit protection limit of the finishing AGC roll gap is set to 3mm.

2. The manufacturing method for producing 6mm thin-gauge steel plates using a heavy plate rolling mill with energy saving and consumption reduction, as described in claim 1, is characterized in that: The finishing rolling process employs 5 to 7 passes of rapid temperature control, with an initial rolling temperature ≥1080℃ and a final rolling temperature ≥850℃. The first pass of the finishing rolling process involves high-pressure water descaling, while the last three passes involve slow biting, controlling the rolling speed to be 2.0 to 3.5 m / s.

3. The manufacturing method for producing 6mm thin steel plates using a heavy plate rolling mill with energy saving and consumption reduction, as described in claim 1, is characterized in that: Before finishing rolling, the pre-filled water opening of the finishing mill is adjusted to 30%.

4. The manufacturing method for producing 6mm thin-gauge steel plates using a heavy plate rolling mill with energy saving and consumption reduction, as described in claim 1, is characterized in that: Before straightening, reduce the water level on the straightener rolls and turn off the external cooling water on the roll table; set the roll speed to 2.5 m / s and quickly feed the rolls from the finishing mill to the straightener.