CN111633027A - Rolling method for extending the life of rolls for conventional hot continuous rolling of thin-gauge strips - Google Patents

Abstract

The invention discloses a rolling method, in particular discloses a rolling method for prolonging the service life of a roller for conventional hot continuous rolling thin-specification strip steel, and belongs to the technical field of steel plate and strip steel rolling processes. The rolling method for prolonging the service life of the roller for the conventional hot continuous rolling thin-specification strip steel is simple in process and low in investment cost. The rolling method achieves the purpose of prolonging the service life of the roller by adopting sectional quantitative rolling arrangement, flexible selection of rolling passes of a roughing mill set and cooling control of finished product rolling to prolong the damage and falling time of an oxide film on the surface of the roller on the premise of controlling the thermal regulation of a rolled plate blank, wherein the finished product rolling is finish rolling.

Description

Rolling method for extending the life of rolls for conventional hot continuous rolling of thin-gauge strips

technical field

The invention relates to a rolling method, in particular to a rolling method for prolonging the life of conventional hot continuous rolling thin strip steel rolls, and belongs to the technical field of steel strip rolling technology.

Background technique

Hot-rolled thin-gauge strip with thickness h≤2.50mm and ultra-thin-gauge strip with thickness h<2.0mm are products with high added value and high technology content. For hot continuous rolling, the stable, high-quality and efficient rolling control of thin-gauge and ultra-thin-gauge hot-rolled strips is a world-class technical problem. Generally speaking, short-flow CSP, ESP, casting and rolling production lines for thin-gauge and ultra-thin-gauge hot-rolled strip have certain advantages in technology, equipment and control. However, for conventional hot continuous rolling, the rolling of thin gauges, especially very thin gauges, is very difficult. Hot-rolled products "replacing cold with heat" and "replacing thick with thin" are a structural demand and development trend. The construction, machinery, automobile and home appliances industries have proposed thin and ultra-thin specifications from the perspectives of energy saving and environmental protection. The demand for hot-rolled strip steel, and the quality requirements such as high strength, light weight and high surface accuracy of the product are required.

With the improvement of conventional hot continuous rolling process equipment and control technology, the dimensional accuracy, shape quality and performance stability of thin-gauge and ultra-thin-gauge products can reach a good level of control, but due to the large rolling load of thin-gauge products, High rolling speed, high temperature, long pure rolling time, and frequent strip threading and tail throwing of conventional hot continuous rolling, the rolling process often causes the oxide film of the finishing rolling work roll to fall off and press into the surface of the strip, resulting in quality defects, and The uneven wear of the rolls is also sensitive to the rolling stability of the strip steel, which often leads to quality problems and production accidents such as deviation, rolling breakage, and wave shape of the strip steel, which directly affects the stability of thin-gauge and ultra-thin-gauge products. Batch and efficient rolling. The scientific, rational and precise arrangement of the strip rolling process in the thin-gauge and ultra-thin-gauge rolling process of conventional hot continuous rolling is an important method to effectively control the surface and stability.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a rolling method for prolonging the life of conventional hot continuous rolling thin strip steel rolls with simple process and low investment cost.

The technical solution adopted to solve the above-mentioned technical problems is: a rolling method for prolonging the life of the rolls used for conventional hot continuous rolling of thin-gauge steel strips. Under the premise, the use of segmented quantitative rolling arrangement, flexible selection of rolling passes of rough rolling unit and cooling control of finished rolling to prolong the damage and shedding time of the oxide film on the surface of the roll to achieve the purpose of prolonging the life of the roll

Wherein, the finished product rolling is finishing mill rolling.

Further, the thermal engineering system is that the slab is heated by a conventional walking beam type heating furnace, and the slab is fed into the furnace by means of hot charging and hot charging. , the release temperature and the rolling temperature are controlled by the upper limit; when the slab is heated in a conventional walking beam heating furnace, the soaking time of the slab is t≥25min, and the temperature difference between the top and bottom of the slab, in the table, and the head and tail △t≤ 25 °C, the heating furnace is increased by 5-10 °C according to the target value of the heating furnace from near to far away from the rolling mill, and the discharge temperature of each furnace.

The preferred way of the above scheme is that, before entering the finishing rolling line, the finishing rolling slab is treated by the hot coil box coiling, heat preservation and uniform technology.

Further, the segmented quantitative rolling arrangement includes three stages of thin-gauge steel strip products with a total number of kilometers of 30-35Km in one rolling unit + intermediate transitional specified strip steel products + thin-gauge steel strip products. alternate rolling,

Among them, the number of kilometers rolled by each stage product is controlled according to the table below.

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The preferred method of the above scheme is that the material and specification requirements of the rolled strip steel products in the intermediate transition section are that the material is Q195, Q235 or SPHC soft steel, the rolling thickness is 2.5-4.0mm, and the rolling thickness is 2.5-4.0mm. The thickness of the thin section rolling is optimal, and the width is 50-100mm larger than the rolling width of the latter section.

Further, the flexible selection of the rolling passes of the roughing mill is made of two roughing mills as a group, and each roughing mill is used to roll three passes respectively, and the first roughing mill is used to roll one pass. Two roughing mills roll 5 passes, the first roughing mill rolls 1 pass, the second roughing mill rolls 3 passes, or the first roughing mill passes the second roughing mill for 5 passes Pass rolling mode control.

The preferred method of the above scheme is that, during the rolling of the finished product, the reverse water spray and the cooling water of the roll gap of the stand before the finished product are turned on, the cooling water of the roll gap of the finished product stand is turned on, and the finishing rolling unit has the function of rolling gap rolling and is put into use. .

The beneficial effects of the present invention are as follows: the rolling method of the present application is based on the existing thermal system, only by adjusting the various procedures and control links of the rolling process, that is, using subsection quantitative rolling to arrange rolling, The flexible selection of rolling passes in the roughing mill and the cooling control of finished rolling can prolong the damage and peeling time of the oxide film on the surface of the roll to achieve the purpose of prolonging the life of the roll. In this way, since the rolling method provided by the present application can achieve the purpose of the invention of the present application only by adjusting the process and key control links, thereby achieving the purpose of ensuring the simplicity of the process without incurring large cost investment. Solve the long-standing and troubled technical problems in the prior art that the oxide film of the rolls is prematurely destroyed and peeled off during the rolling of thin plates (strips) and ultra-thin plates (strips). .

Detailed ways

In order to solve the above-mentioned technical problems existing in the prior art, the present invention provides a rolling method for prolonging the life of conventional hot continuous rolling thin strip steel rolls with simple process and low investment cost. The described rolling method prolongs the surface of the rolls by adopting the subsection quantitative rolling arrangement, the flexible selection of the rolling passes of the rough rolling group and the cooling control of the finished rolling under the premise of controlling the thermal system of the rolled slab. The purpose of prolonging the life of the roll is achieved by the damage and falling off time of the oxide film, wherein the finished product rolling is finishing rolling. The rolling method of the present application is based on the existing thermal system, and only adjusts each process and key control links of the rolling process, that is, adopts segmented quantitative rolling arrangement, and flexible selection of rolling passes by rough rolling mills. And the cooling control of the finished product rolling can prolong the damage and fall off time of the oxide film on the surface of the roll to achieve the purpose of prolonging the life of the roll. In this way, since the rolling method provided by the present application can achieve the purpose of the invention of the present application only by adjusting the process and key control links, thereby achieving the purpose of ensuring the simplicity of the process without incurring large cost investment. The technical problems of poor surface quality and poor rolling stability in the rolling of thin plates (strips) and ultra-thin (strips) plates have been solved for a long time in the prior art.

In the above-mentioned embodiments, in order to make less major adjustments in equipment and processes as much as possible, and at the same time to effectively improve the rolling quality of hot tandem-rolled thin-gauge strip steel and hot-rolled ultra-thin gauge strip steel, the present application The thermal engineering system is as follows: the slab is heated by a conventional walking beam heating furnace, and the slab is fed into the furnace by means of hot feeding and hot charging. The rolling temperature is controlled by the middle upper limit; when the slab is heated in a conventional walking beam heating furnace, the soaking time of the slab is t≥25min, and the temperature difference between the top and bottom of the slab, in the table, and the head and tail is △t≤25℃. The furnace is increased by 5-10 ℃ according to the distance from the rolling mill to the farthest, and the target value of the furnace discharge temperature. At the same time, before entering the finishing mill, the finishing slab should be treated with hot coil box coiling insulation and uniform technology. The tapping temperature and the rolling temperature described here are controlled according to the middle upper limit, that is, the tapping temperature and rolling temperature of 1250° C. and 1050° C. are respectively selected as far as possible.

Of course, in addition to adjusting the process, key control links and parameters, the output of each rolling stage in this application is also specified to protect the oxide film on the surface of the roll. Specifically, the segmented quantitative rolling arrangement includes the alternation of three segments of thin-gauge steel strip products with a total number of kilometers of 30-35Km as one rolling unit + intermediate transition-specified strip steel products + thin-gauge steel strip products Rolling, in which the rolling kilometers of each stage product are controlled according to the table below.

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At this time, the preferred rolling mill layout structure is that the flexible selection of rolling passes of the roughing mill is taken as an example of the configuration of two roughing mills, each roughing mill is used for three passes, and the first roughing mill is used for rolling. 1 pass, 5 passes in the second roughing mill, 1 pass in the first roughing mill, 3 passes in the second roughing mill, or 1 pass in the first roughing mill Rolling mode control of 5 passes of roughing mill. And here: in the finished product rolling, the reverse water spray and roll gap cooling water of the stand before the finished product are turned on, the roll gap cooling water of the finished product stand is turned on, and the finishing rolling unit has the roll gap rolling lubrication function and is put into use. At the same time, this application also proposes the requirements for the material and specifications of the rolled strip steel parts in the intermediate transition section, specifically, the material is Q195, Q235 or SPHC kind of soft steel, the rolling thickness is 2.5 ~ 4.0mm, and It is best to gradually transition to the thin gauge rolling thickness of the latter section, and the width is 50-100mm larger than the rolling width of the thin gauge rolling section of the latter section.

To sum up, the rolling method provided by the present application for extending the life of the rolls for conventional hot continuous rolling thin-gauge strip steel is specifically to control the thin-gauge, especially the ultra-thin-gauge rolling process due to the peeling off of the oxide film of the finishing work roll or the roll. Surface and rolling stability problems caused by uneven wear. Emphasis is placed on the use of innovative, scientific, reasonable and accurate rolling schedule arrangement and flexible process control technology with rough rolling mode, intermediate cooling, hot coil box insulation, temperature uniformity, etc., to control the roll off of oxide film and the unevenness of the roll. Wear and tear, and achieve stable and high-quality rolling of conventional hot-rolled thin-gauge strips. The characteristics of the technical solution of the present application are mainly reflected in the following aspects:

1) The invention innovatively proposes the segmental arrangement and process control technology of the rolling process during the rolling process according to the characteristics of the conventional hot tandem rolling process and the formation and peeling mechanism of the oxide film of the finishing roll, which is creative;

2) The invented thin-gauge strip steel rolling method adopts segmented rolling schedule arrangement and flexible process control technology without increasing production cost, which has novelty and practicability;

The rolling method of the present application effectively controls and improves the surface quality and rolling stability of the thin-gauge rolling process in view of the difficulties and outstanding problems existing in conventional hot continuous rolling thin gauge and ultra-thin gauge, and in combination with actual production. , the rolling stability is improved, the practical technical problems are solved, and the efficient and high-quality mass production of thin-gauge products is realized. The method is novel, creative and practical, and no investment occurs.

specific embodiment

Purpose of the invention: A rolling technology for conventional hot continuous rolling of thin-gauge strip steel, the technology is specifically controlling the thin-gauge, especially the ultra-thin-gauge rolling process due to the peeling off of the oxide film of the finishing rolling work roll or the uneven wear of the roll. and rolling stability issues. The innovative scientific, rational and accurate rolling schedule arrangement and flexible process control technology with rough rolling mode and intermediate cooling are adopted to control the peeling off of the oxide film of the roll and the uneven wear of the roll, so as to realize the thin specification of conventional hot continuous rolling. Stable high-quality rolling of strip.

The specific technical solutions are as follows:

1) Thermal system: The slab is heated by a conventional walking beam heating furnace, and the discharge temperature is 1210-1250 ° C, and the temperature is controlled according to the upper limit; When the tail temperature difference △t≤25℃, the heating furnace is increased by 5-10℃ according to the target value of the furnace discharge temperature from near to far away from the rolling mill. In particular, the best way to charge the slabs is to use hot charging.

2) In particular, according to specific varieties and rolling specifications, in order to ensure the opening temperature of finishing rolling, that is, 1020-1050 °C, the rough rolling mill can flexibly select "3+3", "1+5", "1+3" Or "0+5" rolling mode and intermediate cooling technology.

3) In particular, in order to ensure the temperature uniformity of the strip, before entering the finishing mill, the hot coil box is used to coil the heat preservation and uniform technology.

4) In particular, the rolling schedule of thin-gauge products adopts a segmented quantitative rolling method, that is, thin-gauge products - intermediate transition products - thin-gauge products, and the thin-gauge in the rolling unit is arranged in the transition of finishing rolling and changing rolls. After rolling, the total rolling kilometers of thin gauges in the rolling unit are controlled at 30-35Km. The rolling kilometers here is a professional term in the field, that is, the length of the rolled strip, as shown in Table 1. .

Table 1. Rolling schedule rules of thin gauge segment rolling method,

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5) Material and specification requirements of the transition section: the material is Q195, Q235, SPHC and other soft steel, the rolling thickness is 2.5 ~ 4.0mm, and the rolling thickness is gradually transitioned to the thin specification of the latter section, and the width is larger than that of the latter section. Thin gauge rolling width 50-100mm.

6) During the rolling process, the reverse water spray and the cooling water of the roll gap of the frame before the finished product are turned on, and the cooling water of the roll gap of the finished product frame is turned on.

7) In particular, during the implementation process of the inventive method, the finishing rolling unit has a roll gap rolling lubrication function and is put into use, which can improve the implementation effect. And the combined application of 1) to 7) is the best implementation technical solution.

The technical solution of the present application is mainly to control the surface and rolling stability problems caused by the peeling of the oxide film of the finishing work rolls or the uneven wear of the rolls during the rolling of thin gauges, especially very thin gauges. Emphasis is placed on the use of innovative, scientific, reasonable and accurate segment rolling schedule arrangement and flexible process control technologies such as rough rolling mode and intermediate cooling to control the peeling of the oxide film of the rolls and the uneven wear of the rolls to achieve conventional hot continuous rolling. Stable, high-quality rolling of thin-gauge strip. Through the implementation and application in the past three years, more than 2 million tons of thin gauges of 2.5mm and below and nearly 300,000 tons of ultra-thin gauges below 2.0mm were rolled in a conventional hot continuous rolling production line, the process yield increased by 1.47%, and the rolling scrap rate was reduced. 31.6%, and the rate of surface quality degradation and judgment is reduced by more than 8.0%, with strong practicability and remarkable effect.

Main features of this application:

1) According to the characteristics of the conventional hot tandem rolling process and the formation and peeling mechanism of the oxide film of the finishing roll, the segmental arrangement and process control technology of the rolling process in the rolling process are innovatively proposed, which is creative;

2) The use of segmented rolling schedule arrangement and flexible process control technology without increasing production costs is novel and practical.

3) In view of the difficulties and outstanding problems of conventional hot continuous rolling thin gauge and ultra-thin gauge, combined with the actual production, the surface quality and rolling stability of the thin gauge rolling process are effectively controlled and improved, and the rolling process is improved. It is stable, solves practical technical problems, and realizes efficient and high-quality mass production of thin-gauge products. The method is novel, creative, practical, and does not require investment.

The preferred embodiments of the present invention will be described in detail below in conjunction with specific technical solutions: it should be understood that the preferred embodiments are only for illustrating the technical solutions of the present application, rather than for limiting the protection scope of the present application.

Example 1:

In this example, a 1450mm conventional hot tandem mill is used to roll a thin gauge of 34Km, as follows:

1) Rolling steel grade: SAPH440, slab release temperature 1230-1240℃, soaking time 30min, slab cold loading.

2) The "3+3" rolling mode is adopted for rough rolling. After rolling, it is coiled by the hot coil box for heat preservation and temperature equalization, and then sent to the finishing rolling unit.

3) The starting temperature of the finishing rolling unit is 1030℃, the reverse water spraying and roll gap cooling water of the stand before the finished product are turned on, the roll gap cooling water of the finished product stand is turned on, and the lubricating rolling is put into use.

4) Rolling process preparation: front section SAPH440, specification 2.3×1160mm, 19Km; transition section: SPHC, specification 3.0-2.75mm×1160-1200mm; rear section SAPH440, specification 1.8×1180mm, 15Km.

Implementation Effect:

In this implementation process, the rolling process is stable, the surface and shape quality of the strip steel coil is good, and there is no rolling scrap and downgrade change judgment.

Example 2:

In this example, a 1450mm conventional hot tandem mill is used to roll a thin gauge of 32Km, as follows:

1) Rolling steel grades: SAPH440 and QSTE420, the slab release temperature is 1230-1250°C, the soaking time is 25min, and the slab is hot-loaded.

2) The "1+5" rolling mode is adopted for rough rolling. After rolling, it is coiled by the hot coil box for heat preservation and temperature equalization, and then sent to the finishing rolling unit.

3) The starting temperature of the finishing rolling unit is 1030℃, the reverse water spraying and roll gap cooling water of the stand before the finished product are turned on, the roll gap cooling water of the finished product stand is turned on, and the lubricating rolling is put into use.

4) Rolling process preparation: SAPH440 in the front section, specification 1.5×1100mm, 20Km; transition section: Q235G, specification 3.0-3.5mm×1250mm; QSTE420 in the rear section, specification: 2.3×1200mm, 12Km.

Implementation Effect:

In this implementation process, the rolling process is stable, the surface and shape quality of the strip steel coil is good, and there is no rolling scrap and downgrade change judgment.

Claims (7)

1. A rolling method for prolonging the life of conventional hot continuous rolling thin-gauge strip steel rolls, characterized in that: the rolling method adopts a segmented method under the premise of controlling the thermal system of the rolled slab. Quantitative rolling arrangement, flexible selection of rolling passes of rough rolling unit and cooling control of finished rolling can prolong the damage and shedding time of the oxide film on the surface of the roll to achieve the purpose of prolonging the life of the roll. Wherein, the finished product rolling is finishing mill rolling. 2. The rolling method for prolonging the life of conventional hot continuous rolling thin steel strip rolls according to claim 1, characterized in that: the hot working system is that the slab is heated by a conventional walking beam heating furnace, The furnace is fed into the furnace by hot feeding and hot charging. The furnace temperature is 1210-1250 °C, the rolling temperature is 1020-1050 °C, and the furnace temperature and rolling temperature are both controlled by the upper limit. When the slab is used, the soaking time of the slab is t≥25min, and the temperature difference between the top and bottom of the slab, in the table, and the head and tail is △t≤25℃. . 3. The rolling method for prolonging the life of conventional hot continuous rolling thin-gauge strip steel rolls according to claim 2, characterized in that: before entering the finishing rolling unit, a hot coil box is used for the finishing rolled slab to coil for heat preservation and uniformity. technical processing. 4. The rolling method for prolonging the life of conventional hot continuous rolling thin steel strip rolls according to any one of claims 1 to 3, characterized in that: the segmented quantitative rolling arrangement includes a total number of kilometers of 30-35Km is the alternate rolling of three stages of thin-gauge strip products + intermediate transition specified strip products + thin-gauge strip products in one rolling unit, Among them, the rolling kilometers of each stage product are controlled according to the table below.

5. the rolling method of prolonging the life of the rolls for conventional hot continuous rolling thin gauge strip steel according to claim 4, it is characterized in that: the material and specification requirements of the intermediate transition section rolling strip steel product are, the material adopts Q195, Q235 Or SPHC class of soft steel, the rolling thickness is 2.5-4.0mm, and it is optimal to gradually transition to the back-end thin gauge rolling thickness, and the width is 50-100mm larger than the back-end thin gauge rolling width. 6. The rolling method for prolonging the life of conventional hot continuous rolling thin strip steel rolls according to claim 5, characterized in that: two rough rolling mills are used as a group for the flexible selection of rolling passes of the rough rolling group. , using each roughing mill for 3 passes, the first roughing mill for 1 pass, the second for 5 passes for the second roughing mill, and the first for 1 pass for the second roughing mill. Rolling mode control in which the first roughing mill rolls 3 passes or the first roughing mill passes through the second roughing mill for 5 passes. 7. The rolling method for prolonging the life of conventional hot continuous rolling thin-size strip steel rolls according to claim 5, characterized in that: in the rolling of the finished product, the reverse water spray and the roll gap cooling water of the frame before the finished product are turned on, The roll gap cooling water of the finished stand is turned on, and the finishing mill has the roll gap rolling lubrication function and is put into use.