A method for reducing off-line cutting loss after the acid continuous rolling unit is stopped for roll replacement

Abstract

The present application discloses a method for reducing offline cutting loss after the acid continuous rolling mill stops for roll change, comprising the following steps: selecting the optimal stop roll; controlling the mill stop position; controlling the looper tension; starting the mill for roll change; cutting thickness fluctuations; and rewinding operations. The present application reduces the offline cutting loss rate by 20%-40% after each stop of the acid continuous rolling mill for roll change by optimizing the starting roll change process and process parameter settings, effectively reducing steel and cost losses.

Description

Technical Field

[0001] The present application relates to the technical field of metal rolling, and in particular to a method for reducing off-line cutting loss after an acid continuous rolling unit is shut down for roll replacement. Background Art

[0002] On the rolling production line, when the rolling mill reaches production or changes processing specifications, it is necessary to change the rolls of the five-stand pickling mill. According to quality control requirements, the pickling mill needs to be stopped 2-3 times each time the rolls are changed. Each stop requires offline cutting of the thickness fluctuation of the steel coil caused by the roll change stop. After each roll change, the thickness fluctuation of the steel coil exceeds the tolerance by 20-30 meters, and the offline cutting loss length is 50-60 meters. The offline cutting loss rate caused by each roll change stop is 3-5%, resulting in serious waste of steel and cost. Summary of the invention

[0003] In order to reduce the offline cutting loss caused by the shutdown of the acid continuous rolling mill for roller replacement, the present application provides a method for reducing the offline cutting loss after the shutdown of the acid continuous rolling mill for roller replacement, comprising the following steps:

[0004] Select the best parking ticket;

[0005] Control the stop position of the rolling mill;

[0006] Control the tension of the looper;

[0007] Change rollers and start the machine;

[0008] Fluctuation of resection thickness;

[0009] Rewinding work.

[0010] Further, the selecting of the optimal parking coil includes selecting the steel coil specification, steel coil thickness, and steel coil yield strength, and the selecting of the steel coil specification includes selecting a steel coil corresponding to a rolling mill outlet thickness greater than 0.6 mm as the first candidate steel coil;

[0011] The selecting the thickness of the steel coil comprises selecting the steel coil with the narrowest width from the first candidate steel coils as the second candidate steel coil;

[0012] The selecting the yield strength of the steel coil includes selecting ordinary steel as the third candidate steel coil from the second candidate steel coil;

[0013] The third alternative steel coil corresponding to the steel coil with the least required cutting weight is selected as the optimal parking coil.

[0014] Further, the control of the rolling mill stop position includes:

[0015] Set the mill to non-weld shear mode;

[0016] Set the weld mill speed to 100-140M / Min;

[0017] After the weld passes through the S4 stand, adjust the rolling mill speed to 80-100M / Min;

[0018] After the weld passes through the S5 frame, stop the weld at the mill exit 5-6 meters away from the S5 frame.

[0019] Further, the control of the looper tension includes:

[0020] The minimum rolling force used by control stands S1-S5 is 1.5MN;

[0021] The speed of the pickling process section is 10M / Min, and the speed of the pickling outlet section is controlled to be 10M / Min;

[0022] The tension of the first exit looper of the rolling mill is reduced by 30% from the second-level setting tension, and the tension of the second exit looper of the rolling mill is reduced by 40% from the second-level setting tension.

[0023] Furthermore, the roll changing and starting includes changing the rolls of the rolling mill, setting starting parameters, coil cutting, machine rolling, and recording results.

[0024] Further, the setting of the starting parameters includes adjusting the rolling force of the stands S1-S5 to a minimum rolling force of 1.5MN, regulating the tension of the first outlet looper of the rolling mill to a secondary setting tension; regulating the tension of the second outlet looper of the rolling mill to a secondary setting tension;

[0025] The coil shearing: when the steel coil is transported for 10-20 meters, the coil is sheared according to the specifications of the steel coil;

[0026] The machine tool rolling: after completing the coil shearing, the machine tool rolling is resumed;

[0027] The recorded results include recording the non-weld shear length.

[0028] Further, the cutting thickness fluctuation includes off-line inspection and cutting of the steel coil.

[0029] Further, the offline inspection is carried out according to the standard for offline inspection of the roll change during the parking process;

[0030] The cutting of the steel coil includes judging the weld length according to the recorded non-weld shearing length and the position of the S5 frame deformation zone, and cutting the steel coil.

[0031] Furthermore, the rewinding operation includes stopping the off-line cutting and performing the rewinding operation when the cutting reaches a distance of 4-6 meters from the weld.

[0032] Furthermore, it also includes the unloading operation after the rewinding operation;

[0033] The unloading operation includes adjusting the tail of the strip to form an angle of 50°-70° with the horizontal tangent direction of the parking roll for unloading, and recording the position of the outer ring weld.

[0034] Beneficial effects:

[0035] This application selects the steel coil with the least required cutting weight as the optimal parking coil according to the steel coil specification, steel coil thickness, and steel coil yield strength, thereby reducing the cutting loss rate when cutting the steel coil; by controlling the stop position of the rolling mill, after the roll change and start-up, the working parameter setting of the frame S1-S5 will no longer change due to the change of the steel coil specification, thereby reducing the thickness fluctuation after starting; by controlling the looper tension of the steel coil in the rolling mill, the thickness fluctuation degree caused by the secondary rolling of the steel coil after the roll change and start-up is reduced; the non-weld shear length is obtained in the roll change and start-up step, and in the thickness fluctuation removal step, the steel coil is removed according to the recorded non-weld shear length and the position of the deformation zone of the S5 frame according to the weld length, thereby improving the removal accuracy and avoiding unnecessary cutting loss; through the offline rewinding step, the steel coil with thickness fluctuation is left on the outer ring of the steel coil to avoid repeated secondary removal. This application reduces the offline cutting loss rate by 20%-40% after each acid continuous rolling unit stops and changes rolls by optimizing the start-up and roll change process and process parameter settings, effectively reducing steel and cost losses. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0037] Figure 1 It is a process flow chart of a method for reducing off-line cutting loss after the acid continuous rolling mill unit is shut down for roll replacement provided in an embodiment of the present application;

[0038] Figure 2 is a rack parking position relationship diagram provided in an embodiment of the present application;

[0039] Figure 3 It is a schematic diagram of the offline rewinding position provided in an embodiment of the present application;

[0040] Reference numerals: acid continuous rolling mill group-1; rolling mill-2; weld stop position-3; weld rewinding position-4, strip tail-5, parking coil-6. DETAILED DESCRIPTION

[0041] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application.

[0042] Example 1

[0043] Combined with Figure 1Embodiment 1 provides a method for reducing off-line cutting loss after the acid continuous rolling mill is shut down for roll replacement, comprising the following steps:

[0044] Step 1, selecting the optimal parking coil, including selecting the steel coil specification, steel coil thickness, and steel coil yield strength;

[0045] Step 1.1 Select the steel coil specification, query the PDA curve to find the thickness fluctuation length relationship corresponding to steel coils of different specifications. In order to ensure the smooth start-up process, the mill outlet thickness should be greater than 0.6mm, so the steel coil corresponding to the mill outlet thickness greater than 0.6mm is selected as the first candidate steel coil;

[0046] Step 1.2, selecting the thickness of the steel coil. Since the narrower the width of the steel coil, the lower the corresponding cutting loss rate, the steel coil with the narrowest width is selected from the first candidate steel coil as the second candidate steel coil;

[0047] Step 1.3, select the yield strength of the steel coil. The yield strength of ordinary steel is better than that of high-strength steel. Ordinary steel is selected as the third candidate steel coil in the second candidate steel coil; the weight of the steel coil corresponding to the offline removal is converted according to the specifications of the third candidate steel coil, and the steel coil with the least weight corresponding to the third candidate steel coil to be removed is selected as the optimal parking coil;

[0048] Within the roll life range, as shown in Table 1, the thickness tolerance length corresponding to the roll change and start of different specifications of steel coils is:

[0049] Table 1

[0050]

[0051] In Example 1, the steel type selected is SPCC, the specification is 0.8mm*1280mm, and the steel coil with a yield strength of 213Mpa is the optimal parking coil;

[0052] Step 2: Combine with Figure 2 , Example 1 adopts a five-stand acid continuous rolling mill unit 1,

[0053] Control the stop position of rolling mill 2 to be at the weld stop position 3;

[0054] Step 2.1, set the rolling mill 2 to the non-weld shearing mode; set the weld passing speed of the rolling mill 2 to 140M / Min;

[0055] Step 2.2, after the weld passes through the S4 stand, adjust the speed of the rolling mill 2 to 95 M / Min;

[0056] Step 2.3, after the weld passes through the S5 frame, stop the weld at the exit of the rolling mill 2, 5 meters away from the S5 frame;

[0057] At this time, the weld area has completed the dynamic change of specifications. After the roll is changed and the machine is started, the working parameter settings of the frames S1-S5 will no longer change due to changes in the steel coil specifications, thereby reducing the thickness fluctuation after the machine is started.

[0058] After the rolling mill 2 stops for roll change, the steel coils in the stands S1-S5 are in a tension-free state. The steel coils in the rolling mill 2 are affected by the tension of the steel coils in the loopers at the first and second exits of the rolling mill 2. The deformation zone of the stands S1-S5 will slowly shift toward the entrance of the rolling mill 2. After the roll change, the deformation zone undergoes secondary rolling, causing the thickness fluctuation to increase. Therefore, after the rolling mill 2 stops, execute:

[0059] Step 3, setting the looper tension; including controlling the frames S1-S5 to use a minimum rolling force of 1.5MN, controlling the pickling process section speed to 10M / Min, controlling the pickling exit section speed to 10M / Min, reducing the first exit looper tension of the rolling mill 2 by 30% from the secondary setting tension, that is, adjusting it from 80KN to 56KN, and reducing the second exit looper tension of the rolling mill 2 by 40% from the secondary setting tension, that is, adjusting it from 75KN to 45KN;

[0060] Step 4, changing rolls and starting the machine; including changing rolls of the rolling mill, setting starting parameters, cutting coils, rolling on the machine tool, and recording results;

[0061] Step 4.1, changing the rolls of the rolling mill;

[0062] Step 4.2, setting the starting parameters, including adjusting the rolling force of the S1-S5 stands to the minimum rolling force of 1.5MN, adjusting the tension of the first exit looper of the rolling mill to the second-level setting tension; adjusting the tension of the second exit looper of the rolling mill to the second-level setting tension;

[0063] Step 4.3, coil shearing: the rolling mill starts, and the coil is ready for coil shearing when it is 15 meters long. When the coil is 16 meters long, coil shearing is performed according to the coil specifications.

[0064] Step 4.4, machine tool rolling: after completing the coil shearing, the machine tool rolling is resumed;

[0065] Step 4.5, record the results: record the non-weld shear length of 36 meters and notify the offline inspector of the result;

[0066] Step 5, cutting thickness fluctuations, including off-line inspection and cutting of steel coils;

[0067] Step 5.1, offline inspection includes offline inspection of the roll change during parking according to the standard;

[0068] Step 5.2, according to the recorded non-weld shear length and the position of the deformation zone of the S5 frame, the steel coil is cut off according to the weld length;

[0069] Step 6, rewinding and unloading operations;

[0070] Step 6.1, combine with Figure 3 The rewinding operation includes stopping the off-line cutting and performing the rewinding operation when the cutting reaches 5 meters away from the weld;

[0071] The purpose of performing the rewinding operation is that the outer ring of the parking coil 6 will be damaged to varying degrees during bundling, transportation and lifting. The outer ring will be cut off after the downstream production line is put on line. In order to reduce the cutting loss, the steel coil with thickness fluctuations will be left on the outer ring of the steel coil to avoid repeated secondary cutting;

[0072] Step 6.2, adjust the belt tail 5 to form an angle of 60° with the horizontal tangent direction of the parking roll 6 for unloading;

[0073] Step 6.3, record the weld seam of the outer ring for 5 meters, and remove it in the subsequent production line.

[0074] Embodiment 2:

[0075] The difference from implementation 1 is that within the rolling period of the rolling mill, a steel coil with a steel grade of M4A03, a specification of 1.27mm*1205mm, and a yield strength of 447Mpa is selected as the optimal parking coil.

[0076] Set the shear speed to 120M / Min. After the weld passes through the S4 stand, manually adjust the mill speed to 85M / Min. After the weld passes through the S5 stand, stop the weld at the mill exit, 5 meters from the S5 stand.

[0077] After the rolling mill stops for roll changing, the frames S1-S5 reduce the speed of the pickling process section to 10M / Min under the minimum rolling force of 1.5MN, and the speed of the pickling exit section is reduced to 10M / Min at the same time. At the same time, the setting tension of the first exit looper of the rolling mill is reduced by 30% from the secondary setting tension, that is, adjusted from 85KN to 59KN, and the tension of the second exit looper of the rolling mill is reduced by 40% from the secondary setting tension, that is, adjusted from 80KN to 48KN. At this time, the subsequent roll changing operation is carried out.

[0078] Adjust the rolling force of the S1-S5 stand to the minimum rolling force of 1.5MN, and restore the looper tension at the first and second exits of the rolling mill to the secondary setting tension. The rolling mill starts, and after the steel coil travels 15 meters, the manual shearing preparation operation is carried out. In the state of preparing for shearing, after the steel coil travels 15 meters, the coil shearing operation is carried out, and normal rolling is resumed after the coil is divided. At this time, the non-weld shearing length is 35 meters, and the results are recorded and notified to the offline inspector.

[0079] Stop and change rolls, and conduct offline inspection according to the standard. Cut according to the non-weld shear length provided by the main operator of the rolling mill. When the cutting reaches 5 meters from the weld, stop the offline cutting operation and carry out the rewinding operation. The offline quality inspection personnel adjust the tail of the steel coil to the 5 o'clock position for unloading. At the same time, the system notes: There is a weld in the outer ring of 5 meters, which will be cut off in the subsequent production line.

[0080] By adopting the method provided in this embodiment to reduce the offline cutting loss after the acid continuous rolling mill is shut down for roll changing, the offline cutting loss length is reduced by 20%-40% after each roll change, effectively saving steel coils and production costs.

[0081] The above is only an embodiment of the present application. The common sense such as the known specific structure and characteristics in the scheme is not described in detail here. The ordinary technicians in the relevant field know all the common technical knowledge in the technical field of the invention before the application date or priority date, can obtain all the existing technologies in the field, and have the ability to apply the conventional experimental means before that date. The ordinary technicians in the relevant field can improve and implement this scheme in combination with their own abilities under the enlightenment given by this application. Some typical known structures or known methods should not become obstacles for ordinary technicians in the relevant field to implement this application. It should be pointed out that for the technicians in this field, without departing from the structure of this application, several deformations and improvements can be made, which should also be regarded as the scope of protection of this application, which will not affect the effect of the implementation of this application and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to explain the content of the claims.

Claims

1. A method for reducing off-line cutting loss after a pickling continuous rolling mill is stopped for roll change, characterized in that: The following steps are involved: Select the best parking ticket; Control the stop position of the rolling mill; Control the tension of the looper; Change rollers and start the machine; Fluctuation of resection thickness; Rewinding operation; The selecting of the optimal parking coil includes selecting the steel coil specification, steel coil thickness, and steel coil yield strength; The selecting of the steel coil specification includes selecting a steel coil corresponding to a rolling mill outlet thickness greater than 0.6 mm as a first candidate steel coil; The selecting of the thickness of the steel coil comprises selecting the steel coil with the narrowest width from the first candidate steel coils as the second candidate steel coil; The selecting the yield strength of the steel coil comprises selecting ordinary steel from the second candidate steel coil as the third candidate steel coil; The third candidate steel coil corresponding to the steel coil with the least required cutting weight is selected as the optimal parking coil; The control of the rolling mill stop position comprises: Set the mill to non-weld shear mode; Set the weld mill speed to 100-140M / Min; After the weld passes through the S4 stand, adjust the rolling mill speed to 80-100M / Min; After the weld passes through the S5 stand, stop the weld at the mill exit 5-6 meters away from the S5 stand; The control of the looper tension comprises: The minimum rolling force used by control stands S1-S5 is 1.5MN; Control the pickling process speed to 10M / Min, and control the pickling exit speed to 10M / Min; The tension of the first exit looper of the rolling mill is reduced by 30% from the second-level setting tension, and the tension of the second exit looper of the rolling mill is reduced by 40% from the second-level setting tension.

2. A method for reducing off-line cutting loss after the acid continuous rolling mill is stopped for roll change as claimed in claim 1, characterized in that: The roll changing and starting process includes changing the rolls of the rolling mill, setting starting parameters, coil cutting, machine rolling, and recording results.

3. A method for reducing off-line cutting loss after the acid continuous rolling mill is stopped for roll change as claimed in claim 2, characterized in that: The setting of the starting parameters includes adjusting the rolling force of the stands S1-S5 to the minimum rolling force of 1.5MN, and regulating the tension of the first exit looper of the rolling mill to the second level setting tension; Adjust the tension of the second exit looper of the rolling mill to the second level setting tension; The coil shearing: when the steel coil is transported for 10-20 meters, the coil is sheared according to the specifications of the steel coil; The machine tool rolling: after completing the coil shearing, the machine tool rolling is resumed; The recorded results include recording the non-weld shear length.

4. A method for reducing off-line cutting loss after the acid continuous rolling mill is stopped for roll change as claimed in claim 1, characterized in that: The cut thickness fluctuation includes off-line inspection and cutting of steel coils.

5. A method for reducing off-line cutting loss after the acid continuous rolling mill is stopped for roll change as claimed in claim 4, characterized in that: The offline inspection is carried out according to the standard for offline inspection of the roll changing when the roll is stopped; The cutting of the steel coil comprises: The steel coil is cut off according to the recorded non-weld shear length and the position of the deformation zone of the S5 frame to determine the distance from the weld.

6. A method for reducing off-line cutting loss after the acid continuous rolling mill is stopped for roll change as claimed in claim 1, characterized in that: The rewinding operation includes stopping the off-line cutting and performing the rewinding operation when the cutting reaches 4-6 meters away from the weld.

7. A method for reducing off-line cutting loss after the acid continuous rolling mill is stopped for roll change as claimed in claim 1, characterized in that: It also includes the unloading operation after the rewinding operation; The unloading operation includes adjusting the tail of the strip to form an angle of 50°-70° with the horizontal tangent direction of the parking roll for unloading, and recording the position of the outer ring weld.

Images