Roll shifting method for prolonging rolling period of working rolls of hot-rolled strip steel endless rolling finishing mill group

Abstract

The invention belongs to the technical field of hot-rolled strip steel production control, and particularly relates to a roll shifting method for prolonging the rolling period of working rolls of a hot-rolled strip steel endless rolling finishing mill group, which comprises the following steps of: configuring long-stroke working roll shifting systems for 3-4 finishing mill racks close to the downstream in the finishing mill group; roll shifting is carried out when rolling of every 1-2 coils of strip steel is completed, the initial roll shifting position is close to the limit roll shifting position when casting rolling of the first coil of strip steel is started, a reciprocating roll shifting strategy that one-way roll shifting or roll shifting direction change does not exceed one time is adopted, the single roll shifting step length is controlled not to exceed 10 mm, and the roll shifting speed does not exceed 1.0 mm / s; and the roll shifting position distribution covers the whole roll shifting stroke as much as possible. According to the invention, the abrasion of the roller is obviously dispersed, the abrasion curve tends to be smooth, the local abrasion aggravation phenomenon is weakened or avoided, the axial shifting load is favorably reduced, the plate shape instability, strip steel deviation or steel piling accidents in the roller shifting process are avoided, and the service life of the roller bearing is favorably prolonged.

Description

Technical Field

[0001] The invention belongs to the technical field of hot-rolled strip production control, and in particular relates to a roll shifting method for improving the roll life of working rolls of a hot-rolled strip headless rolling finishing mill. Background Art

[0002] Thin slab continuous casting and rolling headless rolling production technology is an important development direction of green and low-carbon production of hot-rolled strip steel. It can produce thin-gauge, high-strength, stable-size and performance steel products, and realize "replacing cold with heat" for some varieties. Under the headless rolling process, although threading and tail swinging are eliminated, the size, temperature and structural performance consistency of the whole roll of strip steel are good, and advanced roller shifting and plate shape control systems are also configured. However, due to the wear of the rollers in continuous online service for a long time, the warping and wave shape of the uncoiled strip steel still exist at room temperature. Especially in the headless rolling process of thin-gauge strip steel, the wear is aggravated, resulting in the plate shape state and the local high points of the cross-sectional size are difficult to control, and the steel coil is prone to defects such as ribs and bulging.

[0003] The main reasons for the above defects are: in the headless rolling production, the same casting is rolled with the same width under the same crystallizer mold width. Due to the low edge temperature of the strip, the lateral flow of the strip and the distribution of the roll crown, the rolling force is unevenly distributed laterally. With the increase of the rolling kilometers, the roll wear on the edge of the strip is getting bigger and bigger, causing serious local wear and forming "cat ears" wear. In particular, the 3 to 4 finishing stands near the downstream of the finishing stand have the most serious uneven wear of the rolls due to the large rolling length and rolling load. The serious "cat ears" wear is reflected on the strip to form the cross-section warping or local high points, which deteriorates the cross-sectional shape of the strip, not only affecting the plate shape and surface quality of the finished strip, but also seriously affecting the rolling kilometers in the roll change cycle, reducing the casting productivity and yield rate. With the increasing market competition, users have more and more stringent requirements on the quality of the strip shape. In addition to the convexity and straightness requirements, they also put forward higher requirements on the profile of the strip, especially the local "cat ears" of the strip are required to be controlled within a small range. In addition, increasing the number of continuous casting furnaces and improving casting productivity are also urgent requirements for headless rolling production to increase the yield rate and reduce production costs.

[0004] In order to achieve the above goals, the key is to reduce the wear of the working rolls in a single casting, especially to reduce the wear of the rolls of 3 to 4 finishing mills downstream of the finishing mill, improve the uniformity of wear, and avoid plate shape defects and premature roll offline caused by increased local wear. Summary of the invention

[0005] In view of this, the object of the present invention is to provide a method for improving the roll shifting of the working rolls of the hot strip headless rolling finishing mill, so as to disperse the roll wear, make the wear curve tend to be smooth, reduce or avoid the phenomenon of local wear aggravation, improve the plate shape control and maintenance ability of the working rolls, realize long roll period headless rolling, improve casting productivity and yield rate, reduce production costs, and improve product quality and economic benefits.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A method for improving the roll shifting of working rolls in a hot strip endless rolling finishing mill, in which 3 to 4 finishing mill stands close to the downstream in the rolling direction are equipped with a long-stroke working roll shifting system, and the maximum roll shifting stroke S is controlled. max ≥400mm.

[0008] In a complete rolling run of normal production, the roll shifting operation of 3 to 4 finishing mill stands downstream in the rolling direction is carried out in the following manner:

[0009] A. Each finishing rolling stand performs a work roll shifting operation when rolling of every 1 to 2 coils of steel strip is completed. The roll shifting operation is performed at the tail of the current steel coil, or the head of the next steel coil, or in the transition section between two adjacent steel coils;

[0010] B. When each finishing mill starts to roll the first strip, the initial roll shifting position S0 (mm) is near the limit roll shifting position on the operating side or the transmission side. When the initial roll shifting position S0 (mm) is near the limit roll shifting position on the operating side, it should meet -L min ≤S0≤-L min +20; When the initial roller shifting position S0 (mm) is near the limit roller shifting position on the transmission side, L max -20≤S0≤L max

[0011] C. Each finishing rolling stand preferably adopts a unidirectional roll shifting strategy, and secondly adopts a reciprocating roll shifting strategy and controls the number of roll shifting direction changes to not more than once;

[0012] D. The single step length of roller shifting of each finishing mill stand does not exceed 10 mm, preferably 4 to 6 mm, and equal step length roller shifting is adopted;

[0013] E. In order to make the roll shifting position distribution of each finishing mill stand cover the entire roll shifting stroke as much as possible, the minimum value S of the roll shifting position in each finishing mill stand is recorded respectively. min (mm) and maximum S max (mm);

[0014] When the initial roller shifting position S0 (mm) is near the limit roller shifting position on the operating side, the maximum roller shifting position S is controlled. max (mm)Meet L max -30≤S max ≤L max ;

[0015] When the initial roller shifting position S0 (mm) is near the limit roller shifting position on the transmission side, the minimum roller shifting position S is controlled. min (mm)Meet-L min ≤S min ≤-L min +30;

[0016] F. Control the working roll shifting operation to shift horizontally at a relatively uniform roll shifting speed. The working roll shifting speed should be ≤1.0mm / s.

[0017] Furthermore, when the first roll of strip steel is cast and rolled, in order to make full use of the working roll shifting stroke, the distance from the initial roll shifting position S0 (mm) of the working rolls in the 3 to 4 finishing mills downstream along the rolling direction to the limit roll shifting position on the operating side or the transmission side is preferably controlled within 5 mm.

[0018] Furthermore, in a complete pouring run of normal production, 5 to 15 transition steel coils of varying specifications are opened for pouring. When the roll shifting operation is performed between the coils, a small step length roll shifting is preferably used, and the roll shifting step length is selected to be 1 to 3 mm. In the stable rolling stage, the roll shifting step length can be appropriately increased. Under the condition that the roll shifting step length does not exceed 10 mm, the roll shifting step length is preferably 4 to 6 mm, and equal step length roll shifting is preferred.

[0019] Furthermore, when the 3 to 4 finishing mills downstream along the rolling direction adopt a one-way roll shifting strategy, the working rolls perform one-way roll shifting from near the maximum roll shifting position on the operating side or the transmission side to the other side, and no longer perform reverse reciprocating roll shifting after reaching near the maximum roll shifting position on the other side.

[0020] Furthermore, when the 3 to 4 finishing mills downstream along the rolling direction adopt the reciprocating roll shifting strategy, the number of roll shifting direction changes should be controlled to not exceed 1 time, that is, the working rolls perform unidirectional roll shifting from near the maximum roll shifting position on the operating side or the transmission side to the other side, and perform reverse reciprocating roll shifting after arriving near the maximum roll shifting position on the other side, and complete the rolling of the casting before the roll shifting position returns to the initial roll shifting position, stop the roll shifting, and do not perform the second roll shifting direction change operation.

[0021] The beneficial effects of the present invention are:

[0022] 1. The 3 to 4 finishing mills in the finishing mill group with the most serious wear near the downstream are equipped with a long-stroke working roll shifting system, and the roll shifting operation is carried out after every 1 to 2 coils of steel are rolled. In addition, the roll shifting position distribution of each finishing mill is made to cover the entire roll shifting stroke as much as possible within a completed casting. This can effectively disperse the roll wear, make the wear curve smooth, reduce or avoid the phenomenon of local wear aggravation, improve the plate shape control and maintenance ability of the working roll, extend the working roll life, realize long-roll life headless rolling, improve casting productivity and yield rate, reduce production costs, and improve product quality and economic benefits.

[0023] 2. By controlling the initial roll shifting position to be near the limit roll shifting position on the operating side or the transmission side when the first roll of strip is rolled, and preferably adopting a one-way roll shifting strategy, and secondarily adopting a reciprocating roll shifting strategy and controlling the number of roll shifting direction changes to not exceed 1 time, so as to reduce the single roll shifting step length; on the premise of making full use of the roll shifting stroke to disperse the roll wear, the single roll shifting step length of the working rolls of each finishing rolling stand of the headless rolling finishing mill is controlled to be no more than 10mm, and the roll shifting speed is limited to below 1.0mm / s, which can reduce the axial shifting load, enhance the rolling stability, avoid unstable plate shape, strip deviation or steel piling accidents during roll shifting, and increase the service life of the roll bearings.

[0024] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

[0026] Figure 1 It is a distribution diagram of the roll shifting positions of the working rolls in the embodiment and the comparative example within a complete casting cycle;

[0027] Figure 2 It is the roll wear distribution diagram of the working roll in the embodiment and the comparative example within a complete casting. DETAILED DESCRIPTION

[0028] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0029] Among them, the drawings are only used for illustrative explanations, and they only represent schematic diagrams rather than actual pictures, and should not be understood as limitations on the present invention. In order to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0030] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "front", "rear", etc. indicate the orientation or position relationship, they are based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0031] First of all, it should be noted that in the working roll shifting system, usually when the midpoint of the upper working roll body is located at the rolling center line, the roll shifting zero position is S = 0mm; the upper working roll shifting toward the transmission side is the positive direction, and the shifting toward the operating side is the negative direction. When the distance from the midpoint of the upper working roll body to the transmission side of the rolling center line is x mm, the roll shifting position at this location is S = +x mm, and when the distance from the midpoint of the upper working roll body to the operating side of the rolling center line is x mm, the roll shifting position at this location is S = -x mm; the maximum limit roll shifting position of the working roll in the negative direction is -L min mm, the maximum limit roller shifting position in the positive direction is +L max mm, then the maximum roll shifting stroke of a finishing mill stand working roll is S max =(L min +L max )mm.

[0032] Example 1

[0033] In a hot strip endless rolling production line equipped with 4 roughing stands and 5 finishing stands, the 3 finishing stands close to the downstream in the rolling direction of the production line are equipped with a long-stroke work roll shifting system, and the maximum shifting stroke of the work rolls is controlled to S max =460mm, and the maximum limit roll shifting position of the working roll in the negative direction is -230mm (the limit roll shifting position on the operating side), and the maximum limit roll shifting position in the positive direction is +230mm (the limit roll shifting position on the transmission side).

[0034] In a complete rolling run of normal production, the roll shifting operation of the three finishing mill stands downstream in the rolling direction is performed in the following manner:

[0035] A. When each coil of steel strip is rolled, the working roll shifting operation is performed at the tail of the current steel coil;

[0036] B. When each finishing rolling stand starts to roll the first strip, in order to make full use of the work roll shifting stroke, the initial roll shifting stroke position is set at S0 = -225 mm, that is, the upper working roll is near the limit roll shifting position on the operating side, and the corresponding lower working roll is near the limit roll shifting position on the transmission side (i.e. +225 mm);

[0037] C. Each of the finishing rolling stands adopts a one-way roll shifting strategy;

[0038] D. Each finishing rolling stand adopts equal step length roll shifting, and the single roll shifting step length is set to 5mm;

[0039] E. It is planned to roll 90 coils of steel strip in this casting, which requires 89 roll shifting. At the end of the casting, the roll shifting position of each finishing mill stand is S=+220mm, achieving the goal of covering the entire roll shifting stroke as much as possible;

[0040] F. Control the working roll shifting operation to shift horizontally at a relatively uniform roll shifting speed. The working roll shifting speed is set to 0.3 mm / s.

[0041] like Figure 1 As shown in FIG. 1 , the shifting positions of the working rolls during rolling of each strip steel roll in a complete casting run are shown when this roll shifting strategy is adopted. Figure 2 As shown, the cumulative wear distribution curve of the working roll of the first rolling mill in the three finishing mills downstream along the rolling direction after a complete casting and rolling based on the above working conditions is simulated and calculated by the roll wear calculation software. It can be seen from the figure that after the roll shifting method is used for control, the roll wear width covers most of the area in the length direction of the working roll body, the wear is dispersed, the curve is smooth, and there is no obvious local wear peak, which is beneficial to enhance the working roll plate shape control and maintenance ability and extend the working roll life.

[0042] Example 2

[0043] In a hot strip endless rolling production line equipped with 3 roughing stands and 5 finishing stands, the 3 finishing stands close to the downstream along the rolling direction of the production line are all equipped with a long-stroke working roll shifting system, and the maximum shifting stroke of the working roll is S max =460mm, the maximum limit roll shifting position of the working roll in the negative direction is -230mm, and the maximum limit roll shifting position in the positive direction is +230mm.

[0044] In a complete rolling run of normal production, the roll shifting operation of the three downstream finishing mill stands along the rolling direction is performed in the following manner:

[0045] A. When each coil of steel strip is rolled, the working roll shifting operation is performed at the head of the next coil;

[0046] B. When each finishing rolling stand starts to roll the first strip, in order to fully utilize the work roll shifting stroke, the initial roll shifting position is set at S0=-225mm, that is, the upper working roll is at the limit roll shifting position on the operating side;

[0047] C. Each finishing rolling stand adopts a reciprocating roll shifting strategy and controls the number of roll shifting direction changes to 1 time;

[0048] D. Each finishing rolling stand adopts equal step length roll shifting, and the single roll shifting step length is set to 10mm;

[0049] E. In this casting, 90 rolls of strip steel are planned to be rolled, and 89 roll shiftings are required. At the end of the casting, the roll shifting position of each finishing mill stand is S = -215 mm. The minimum roll shifting position of each finishing mill stand in the casting is S. min =-225mm, maximum value is S max = +225mm, achieving the goal of covering the entire roller shifting stroke as much as possible;

[0050] F. Control the working roll shifting operation to shift horizontally at a relatively uniform roll shifting speed. The working roll shifting speed is set to 0.3 mm / s.

[0051] Figure 1 The figure shows the shifting positions of the working rolls during rolling of each strip within a complete casting when this roll shifting strategy is adopted. Figure 2The figure shows the cumulative wear distribution curve of the working roll of the first rolling mill in the three finishing mills downstream along the rolling direction after a complete casting and rolling based on the above working conditions, which is simulated and calculated by the roll wear calculation software. It can be seen from the figure that after the roll shifting method is used for control, the roll wear width covers most of the area in the length direction of the working roll body, the wear is dispersed, the curve is smooth, and there is no obvious local wear peak, which is beneficial to enhance the working roll plate shape control and maintenance ability and extend the working roll life.

[0052] Comparative Example 1

[0053] In a hot strip endless rolling production line equipped with 3 roughing stands and 5 finishing stands, a long-stroke working roll shifting system is configured for the 3 finishing stands downstream in the rolling direction of the production line, and the maximum shifting stroke of the working rolls is S max =460mm, the maximum limit roll shifting position of the working roll in the negative direction is -230mm, and the maximum limit roll shifting position in the positive direction is +230mm.

[0054] In a complete rolling run with a planned normal production of 90 rolls of strip steel, the initial roll shifting position of the three finishing mills downstream along the rolling direction is set at S0=0mm, that is, the midpoint of the roll body of the upper and lower working rolls coincides with the rolling center line, and no roll shifting operation is performed during the entire run, that is, the roll shifting position is always maintained at S=0mm.

[0055] Figure 1 The figure shows the shifting positions of the working rolls during rolling of each strip within a complete casting when this strategy is adopted. Figure 2 The cumulative wear distribution curve of the working roll of the first mill in the three finishing mills downstream along the rolling direction after a complete casting and rolling based on the above working conditions is shown in the figure. It can be seen from the figure that after adopting this strategy control, the roll wear width is smaller, the wear is more concentrated, the peak wear amount is larger, and there is a more serious "cat ear" phenomenon, which will seriously deteriorate the plate shape control ability of the working roll, resulting in a shorter rolling mileage of the working roll and the inability to achieve long roll period rolling.

[0056] Comparative Example 2

[0057] In a hot strip endless rolling production line equipped with 3 roughing stands and 5 finishing stands, the 3 finishing stands downstream in the rolling direction of the production line are all equipped with a long-stroke working roll shifting system, and the maximum shifting stroke of the working rolls is S max =460mm, the maximum limit roll shifting position of the working roll in the negative direction is -230mm, and the maximum limit roll shifting position in the positive direction is +230mm.

[0058] In a complete rolling run of normal production, the roll shifting operation of the three downstream finishing mill stands along the rolling direction is performed in the following manner:

[0059] A. When each coil of steel strip is rolled, the working roll shifting operation is performed at the head of the next coil;

[0060] B. When each finishing rolling stand starts to roll the first strip, in order to fully utilize the work roll shifting stroke, the initial roll shifting position is set at S0=-225mm, that is, the upper working roll is at the limit roll shifting position on the operating side;

[0061] C. Each finishing mill adopts a reciprocating roll shifting strategy, and the number of roll shifting direction changes is not limited. When the roll shifting position reaches the limit roll shifting position and the one-way roll shifting can no longer be continued, the roll shifting direction is changed;

[0062] D. Each finishing rolling stand adopts equal step length roll shifting, and the single roll shifting step length is set to 20mm;

[0063] E. In this casting, 90 rolls of strip steel are planned to be rolled, and 89 roll shifting is required. At the end of the casting, the roll shifting position of each finishing rolling stand is S = -205mm. The minimum roll shifting position of each finishing rolling stand in the casting is S. min =-225mm, maximum value is S max = +215mm, achieving the goal of covering the entire roller shifting stroke as much as possible;

[0064] F. Control the working roll shifting operation to shift horizontally at a relatively uniform roll shifting speed. The working roll shifting speed is set to 0.3 mm / s.

[0065] Figure 1 The figure shows the shifting positions of the working rolls during rolling of each strip within a complete casting when this roll shifting strategy is adopted. Figure 2 The cumulative wear distribution curve of the working roll of the first mill in the three finishing mills downstream along the rolling direction after a complete casting and rolling based on the above working conditions is shown in the figure. It can be seen from the figure that after the roll shifting method is used for control, the roll wear width covers most of the area in the length direction of the working roll body, and the wear is relatively dispersed, but the wear curve is poor in smoothness and symmetry, and there is a phenomenon of local wear aggravation, which is not conducive to extending the rolling mileage.

[0066] By comprehensively comparing the wear conditions of the embodiments and the comparative examples, a headless rolling working roll shifting strategy with a large stroke, a small step length, covering the roll shifting stroke as much as possible, and changing the roll shifting direction in one direction or only once is adopted. The working roll wear width is wider, the utilization rate of the roll shifting stroke is higher, the roll wear is more evenly dispersed, the wear peak can be effectively reduced, and the wear curve is smoother, without obvious "cat ears" or local wear aggravation, which is conducive to achieving long roll rolling.

[0067] Compared with Example 1, the peak and smoothness of the roll wear curve under the roll shifting strategy of Example 2 are comparable, and from the perspective of extending the roll life, there is no more prominent advantage. Considering that the roll shifting step length of Example 2 is larger, it may increase the risk of plate shape instability, strip deviation or steel accumulation accidents during the roll shifting process, which is not conducive to the service life of the roll bearing, and requires a longer roll shifting time, which is not conducive to the stable control of the rolling process. Therefore, compared with the two embodiments, Example 1 is the preferred solution, that is, on the premise of covering the effective roll shifting stroke as much as possible, it is preferred to adopt a one-way roll shifting strategy, reduce the roll shifting step length and roll shifting time, and enhance the stability of the headless rolling production process.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. A method for improving the roll shifting of working rolls of a hot strip endless rolling finishing mill, characterized in that: The 3-4 finishing stands near the downstream of the rolling direction in the hot strip endless rolling finishing mill are all equipped with a long-stroke work roll shifting system, and the maximum roll shifting stroke S of the long-stroke work roll shifting system is controlled. max ≥400mm; And in a complete rolling run, the following control method is used to perform roll shifting operation on the finishing mill stand equipped with a long-stroke work roll shifting system: A. When every 1-2 rolls of strip steel are rolled, the roll shifting operation is performed, and the roll shifting operation is controlled to be performed at the tail of the current roll of strip steel, or the head of the next roll of strip steel, or in the transition section between two adjacent rolls of strip steel; B. When rolling the first roll of strip steel, control the initial roll shifting position S0 in each finishing mill stand equipped with a long-stroke work roll shifting system to be close to the operating side limit roll shifting position -L min Or the transmission side limit roller position L max ; When the initial roll shifting position is close to the limit roll shifting position on the operating side, -L min ≤S0≤-L min +20mm; when the initial roller shifting position is close to the limit roller shifting position on the transmission side, L max -20mm≤S0≤L max ; C. When performing roll shifting operation, a one-way roll shifting strategy or a reciprocating roll shifting strategy is adopted, and when the reciprocating roll shifting strategy is adopted, the number of roll shifting direction changes must be controlled to not exceed 1 time; D. When performing roller shifting operation, control the single roller shifting step length to no more than 10mm; E. Record the minimum value S of the roll shifting position of each finishing stand in a complete rolling process min and the maximum value S max ; When the initial roller shifting position is close to the limit roller shifting position on the operating side, the maximum value S of the roller shifting position is controlled. max Meet L max -30mm≤S max ≤L max ; When the initial roller shifting position is close to the limit roller shifting position on the transmission side, the minimum value S of the roller shifting position is controlled. min Satisfy-L min ≤S min ≤-L min +30mm; F. Control the working roll shifting speed ≤1.0mm / s.

2. The roll shifting method for improving the working roll life of the hot strip endless rolling finishing mill according to claim 1 is characterized in that: When the first roll of strip steel is rolled, the distance between the initial roll shifting position in each finishing mill stand equipped with a long-stroke working roll shifting system and the operating side limit roll shifting position or the transmission side limit roll shifting position is controlled to be within 5 mm.

3. The method for improving the roll shifting period of the working rolls of the hot strip endless rolling finishing mill according to any one of claims 1 to 2, characterized in that: For transitional steel coils with 5 to 15 rolls of variable specifications, the step length of roller shifting is selected to be 1 to 3 mm.

4. The roll shifting method for improving the working roll life of the hot strip endless rolling finishing mill according to claim 3 is characterized in that: After the rolling of the first 5 to 15 transitional steel coils of varying specifications is completed and the stable rolling stage is entered, the roll shifting step length is selected to be 4 to 6 mm, and the roll shifting is performed with equal step lengths.

5. The roll shifting method for improving the working roll life of the hot strip endless rolling finishing mill according to claim 1, characterized in that: When the one-way roll shifting strategy is adopted, the working roll shifts one-way from the initial roll shifting position close to the maximum roll shifting position on the operating side or the maximum roll shifting position on the transmission side to the other side, and no longer performs reverse reciprocating roll shifting after reaching the maximum roll shifting position on the other side.

6. The roll shifting method for improving the working roll life of the hot strip endless rolling finishing mill according to claim 1, characterized in that: When the reciprocating roll shifting strategy is adopted, the working roll shifts unidirectionally from the initial roll shifting position close to the maximum roll shifting position on the operating side or the maximum roll shifting position on the transmission side to the other side, and then reciprocates in the reverse direction after reaching the maximum roll shifting position on the other side, and completes the rolling of the casting before the roll shifting position returns to the initial roll shifting position, and then stops the roll shifting.

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